JP4687198B2 - Laminated metal can, method for producing the same, and method for producing the film - Google Patents

Description

  The present invention relates to a laminated metal can for beer and sparkling liquor, a method for producing the same, a method for producing a film for a laminated metal can for beer and sparkling liquor, and a method for producing a metal plate for a laminated metal can for beer and sparkling liquor.

  In recent years, froth-conscious beer and sparkling liquor products are on the market. For example, a glass that produces creamy foam when poured or a server for home use. The foam of beer and happoshu has given great appeal to products called beer and happoshu. In the metal can field for beer and sparkling liquor, there are some products that are devised for foam. For example, there is a device with a spout that can easily generate bubbles when poured, and a can filled with an item that induces foaming when opened.

Metal cans have a function to store the contents and a function to use them as glass.
These functions are limited to one time until the contents are drunk. After drinking, the functions are recycled and the role as a can is finished. Therefore, an inexpensive can is more preferred.

  In a beer / sparkling liquor can with foaming properties, a can in which a foam-inducing item is enclosed is generally not widespread and is applied only to specific contents. On the other hand, cans that easily generate bubbles when pouring are only cheaply devised because the shape of the spout is devised, but if you use this function, the function of the can as a glass In addition to being abandoned, since it is greatly affected by the pouring container and the pouring method, a stable and good foaming property cannot be obtained.

  As a technique for imparting foaming properties without causing a significant increase in can cost, Patent Document 1 discloses that protrusions are formed by baking a paint with added granules on the inner surface of an aluminum can or after applying the paint. A technique for improving the foaming property of carbonated beverages by forming a conical or pyramidal concave portion having a substantially V-shaped cross section by pressing is disclosed, and Patent Document 2 discloses two or more layers. A biaxially stretched laminated polyester film that contains particles that are relatively spherical in the polyester of the non-metal plate side layer, and has uniform irregularities on the surface to make the surface roughness uniform. A technique for improving foamability is disclosed.

However, when the present inventors evaluated the foaming properties of beer / happoshu based on the description of Examples in Patent Documents 1 and 2, considering the actual use environment, good foaming properties were not obtained. It was.
Japanese Patent Laid-Open No. 05-97149 JP-A-11-254625

  An object of the present invention is to produce a laminated metal can that exhibits good foaming properties in an actual use environment when filled with beer or sparkling liquor without significantly increasing the can cost, and production of the film for the metal can It is providing the method, the manufacturing method of this metal plate for metal cans, and the manufacturing method of this metal can.

  Means of the present invention for solving the above problems are as follows.

[1] A metal can having a laminate resin layer on a metal plate on the inner surface side of the can, wherein the laminate resin layer has a groove on its surface, and the groove has a maximum width of 5.0 μm in cross-sectional shape. Below, the groove width is narrow on the steel plate side, the portion where the groove width is 1.0 μm or less in the groove depth direction has a depth of 0.5 μm or more, and the groove portion per unit area of the inner surface of the can The total length of is 10 mm / mm ² or more and 300 mm / mm ² or less.

  [2] The laminated metal can according to [1], wherein at least the outermost layer of the laminated resin layer is made of a resin mainly composed of a thermoplastic polyester.

[3] The thermoplastic polyester resin is obtained by condensation polymerization of a dicarboxylic acid component and a diol component, the dicarboxylic acid component is composed of terephthalic acid, or terephthalic acid and isophthalic acid, and the diol component is composed of ethylene glycol and / or butylene glycol. And a repeating unit composed of ethylene terephthalate or butylene terephthalate is any resin selected from the following (1) to (5) having a molar ratio of 85% or more [2] A laminated metal can described in 1.
(1) Polyethylene terephthalate-polyethylene isophthalate copolymer (2) Polyethylene terephthalate (3) Polybutylene terephthalate-polyethylene terephthalate copolymer (4) Polyethylene terephthalate-polyethylene isophthalate-polybutylene terephthalate copolymer (5) Polybutylene The laminated resin layer of terephthalate [4] [2] has at least the outermost layer as a main component of a thermoplastic polyester whose main phase is the resin of claim 3 as a main skeleton, and the subphase is made of polyolefin. The laminated metal can according to [2], which comprises a mixed resin.

  [5] The laminated metal can according to [4], wherein the polyolefin comprises one or more of polyethylene, polypropylene, and ionomer.

  [6] The laminated metal can according to any one of [1] to [5], wherein a surface orientation coefficient of a surface resin layer of the laminate resin layer is 0.02 or less.

  [7] The laminated metal can according to any one of [1] to [6], wherein the laminated resin layer is formed by an extrusion method or is formed by thermocompression bonding of an unstretched film. .

  [8] With respect to a film made of a resin having a thermoplastic polyester as a main component at least on one surface, a resin having a thermoplastic polyester as a main component as a main component (the outermost layers on both surfaces are made of thermoplastic polyester). The method for producing a film for a laminated metal can according to [1] or [2], wherein a film made of a resin as a main component is subjected to a treatment of spraying water vapor on the surface of one resin).

  [9] The method for producing a film for a laminated metal can according to [8], wherein water vapor is sprayed on the surface of the film in a state where the film temperature is 80 ° C. or more and not more than the melting point of the outermost layer resin.

  [10] With respect to a laminated metal plate having at least one outermost layer made of a resin mainly composed of a thermoplastic polyester on one surface of the metal plate, the outermost thermoplastic polyester is a major component. The manufacturing method of the metal plate for laminated metal cans which performs the process which sprays water vapor | steam on the surface of resin.

  [11] The method for producing a metal plate for a laminated metal can according to [10], wherein water vapor is sprayed on the laminated metal plate in a state where the temperature of the laminated metal plate is 80 ° C. or higher and not higher than the melting point of the outermost layer resin. .

[12] A metal plate for a laminated metal can produced by the method according to [10] or [11], wherein the resin having the outermost thermoplastic polyester as a main component is on the inner surface side of the metal can, The laminate according to [1] or [2], wherein drawing is performed so that a region in which the degree of work in the circumferential direction defined by the formula is 60% or more exists in an area ratio of 1/4 or more of the can body Manufacturing method of metal cans.
Circumferential machining degree (%) = (peripheral length after machining) / (peripheral length before machining) × 100
Here, the circumferential length before processing is the circumferential length of an arbitrary circle centered on the center point of the blank plate, and the circumferential length after processing is the arbitrary circle when the can body is formed. It is a perimeter.

  According to the present invention, it is possible to obtain a laminated metal can that exhibits good foaming properties simply by opening beer / happoshu without significantly increasing the can cost.

  The present invention will be described below together with the background to the invention.

  In the beer / happoshu can, the inside of the can before opening the lid is in a positive pressure state, and the vapor-liquid equilibrium is maintained in this state. However, when the lid is opened, the pressure becomes atmospheric pressure, the equilibrium is lost, and supersaturated carbon dioxide dissolved in the liquid becomes carbon dioxide and diffuses into the atmosphere. This is the source of bubbles. However, normally, just by opening the lid, the rate of carbon dioxide gas generation is slow and sufficient foaming cannot be achieved. For this reason, in order to make generation | occurrence | production of a bubble remarkable, a device is needed.

  The inventors poured beer / happoshu into a glass by various pouring methods to generate various bubbles, and investigated the amount of foam generated and its size. When beer / happoshu was poured into a glass vigorously, a large amount of large foam was generated, but the foam immediately disappeared. Next, when moderately slowly poured, fine bubbles having a diameter of 1 mm or less were deposited on the upper layer to form an ideal bubble portion. When poured more slowly, no bubble accumulation was observed on the upper layer, and no bubble accumulation was observed even after standing for a while. In the observed range, the bubble size tends to increase when pouring vigorously, and the bubble size tends to decrease when pouring slowly, and the accumulation of bubbles in the upper layer is observed whether it is too vigorous or too slow. From this, it was considered that there was an appropriate bubble size for the deposition of bubbles on the upper layer. That is, it was considered that there was an appropriate bubble size when the bubbles were released into the liquid from the bubble generation point.

  As for the generation point of bubbles, it is said that the wall portion, particularly the hole portion, is advantageous. This is because, when bubbles are generated, the surface energy of the newly generated gas-liquid interface is smaller in the wall than in the liquid and requires fewer holes than in the wall. In order to obtain bubbles having a size suitable for foam accumulation, various foam sizes may be adjusted to obtain good foamability. Therefore, the inventors formed hemispherical holes of sub-micron to millimeter order size on the surface of the laminated steel plate, and investigated the foaming property in beer / happoshu.

  However, as a result, sufficient foamability could not be obtained at any size. Furthermore, although the foamability of a film having a sub-micron or smaller sub-micron surface that was not hemispherical on the film surface was investigated, no improvement in foamability was observed.

  Although the above-mentioned investigation was an investigation on a wide range of pore sizes, it was not possible to find a hole size or irregularity size suitable for forming a foam layer of about 1 mm in the upper layer. The inventors reasoned that this was because bubbles of a size suitable for deposition on the upper layer were generated, but because the number of bubbles of that size was small, the deposition of bubbles on the upper layer was insufficient. Thought.

  Therefore, the inventors examined various methods for generating a large number of bubbles having a size suitable for deposition on the upper layer. As a result, bubbles that are smaller than the size of the bubbles suitable for deposition on the upper layer are generated at the starting point of the bubbles, and the bubbles are grown into bubbles of a size suitable for deposition on the upper layer and then released into the liquid. I got a new idea to make it happen. Since it is possible to have a large number of generation points of fine bubbles, according to this idea, a large number of fine bubbles are generated at the generation point of bubbles, and the bubbles are of a size suitable for deposition on the upper layer. It is possible to generate a large number of bubbles having a size suitable for the deposition of the bubbles on the upper layer by releasing them into the liquid after they are grown.

  Here, paying attention to the fact that the concave portion present on the wall surface can be a starting point of bubbles, an attempt was made to form a groove in the film layer on the inner surface of the can as follows. That is, when the surface of the laminated steel sheet was previously treated with water vapor to embrittle the resin, and deep drawing was performed, the occurrence of grooves was confirmed at a high degree of processing. When the cross section of the groove portion was observed, the cross-sectional shape of the groove portion was wide in the opening width (gap) at the top and narrowed at the bottom. In the groove portion having such a shape, the lower narrow space becomes the starting point of foam generation, and the foam generated there grows while moving to the upper opening wide portion, and after the upper space is filled with foam, It was predicted to diffuse into the inside. Using this sample, a foam test was conducted and confirmed, and good foam generation was observed. Detailed investigation and examination were subsequently continued to arrive at the present invention.

  The reasons for limiting the invention will be described below.

First, a laminated metal can for beer / happoshu will be described.
The laminated metal can for beer and sparkling liquor of the present invention is a metal can having a laminate resin layer on at least a metal plate on the inner surface of the can, and the laminate resin layer on the inner surface of the can has a groove on the surface thereof, The groove portion needs to have a maximum width length of 5.0 μm or less in the cross-sectional shape and a total length of the groove portion per unit area of the inner surface of the can of 10 mm / mm ² or more and 300 mm / mm ² or less. Further, the groove portion has a groove width that is narrower on the steel plate side, and a portion where the groove width becomes 1.0 μm or less in the groove depth direction needs to have a depth of 0.5 μm or more. In this specification, the groove width is narrower on the steel plate side, and the section where the groove width is 1.0 μm or less in the groove depth direction has a depth of 0.5 μm or more is a funnel type cross section. It states that there is.

  Here, the groove portion is a fine concave portion formed almost linearly on the surface of the resin layer, and the maximum width length of the groove portion is a cross-sectional shape when observed in a plane perpendicular to the length direction of the groove. Is the maximum width of the recess. The length of the groove is the length of the substantially linear groove observed in the planar observation.

The reason why the maximum width length of the groove portion is defined as 5.0 μm or less is based on the reason that the groove width exceeding 5.0 μm could not be created, and thus the maximum width length was able to confirm the foaming improvement effect. The reason why the total length of the grooves (groove density) is defined as 10 mm / mm ² or more is based on the fact that the minimum value of the total length of the grooves that has confirmed the foaming improvement effect is 10 mm / mm ² . The reason why the total length of the groove portions is defined as 300 mm / mm ² or less is that when it exceeds 300 mm / mm ² , the amount of foaming becomes too large when the contents are filled in the can body, which causes a practical problem. In addition, the quantity of a groove part targets the groove part which exists in a can body and a can bottom.

  In addition, it is specified that the portion where the groove width is 1.0 μm or less in the groove depth direction has a depth of 0.5 μm or more. The portion where the groove width is 1.0 μm or less is 0. A groove having a depth of 5 μm or more can exhibit more excellent foamability than a groove having a depth of less than 0.5 μm even if there is a part having a groove width of 1.0 μm or less. Because. In the groove where the groove width is 1.0 μm or less and the depth is 0.5 μm or more, fine bubbles are generated in the groove. The generated foam grows in the groove, grows into a foam of a size suitable for deposition on the upper layer of beer / happoshu, and is released into the liquid from the upper part of the groove. The funnel-shaped cross-section generally has an excellent effect of growing the generated fine bubbles into large bubbles. In the present invention, excellent foamability is obtained by generating a large number of bubbles deposited in the upper layer of the beer liquid in the groove portion.

Next, the manufacturing method of the metal can of this invention is demonstrated.
The metal can of the present invention is characterized in that the laminate resin layer on the inner surface of the can has a groove defined by the invention of claim 1 on the surface. A metal can having a groove on the resin layer on the inner surface of the metal can is obtained by embrittlement of the resin surface layer on the side opposite to the metal plate of the resin that is on the inner surface side of the metal plate of the laminated metal plate, and then drawing. As a technique for embrittlement of the resin, for example, a technique of spraying water vapor on the resin surface is exemplified. The process of performing the process of spraying water vapor is not limited. Any of the resin film stage, after laminating the resin film on the metal plate, and before the drawing process in the metal can manufacturing process may be used.

  The spraying of water vapor on the resin surface is preferably performed in a range where the metal plate temperature is 80 ° C. or higher and the melting point of the resin or lower. This is because when water vapor is sprayed on the metal plate that falls within the temperature range, grooves are easily introduced into the film surface in the subsequent drawing process.

  Moreover, it is preferable that the drawing process in a metal can manufacturing process includes the process processed so that the area | region where the processing degree of the circumferential direction may be 60% or more exists in 1/4 or more of a can body. This is because a groove portion can be generated particularly effectively in a region where the processing degree in the circumferential direction is 60% or more, and if the region is present in a quarter or more of the can body, the foaming property is improved. This is because a sufficient amount of grooves can be generated. Although details are unknown, the generation of grooves in drawing is correlated with the amount of shrinkage (working degree) in molding. That is, in the drawing process, the material is stretched in the can height direction and simultaneously contracted in the circumferential direction. As a result of this shrinkage, the groove width becomes narrower on the steel plate side and the groove width becomes 1.0 μm or less on the resin layer surface. A groove (a funnel-type groove) having a depth of 0.5 μm or more is formed. The greater the amount of shrinkage, the greater the amount of groove generated. That is, it is considered that the groove is formed by shrinking.

The degree of processing in the circumferential direction is defined by the following equation.
Circumferential machining degree (%) = (peripheral length after machining) / (peripheral length before machining) × 100
Here, the circumferential length before processing is the circumferential length of an arbitrary circle centered on the center point of the disc-shaped blank plate, and the circumferential length after processing is the above-mentioned when it becomes a can body The circumference of the circle.

  The resin layer suitable for forming the groove by performing the above-described water vapor spray treatment and drawing is at least the outermost layer made of a resin whose main component is thermoplastic polyester.

  Moreover, the following are more preferable from a viewpoint of formation of a groove part, cost, and food hygiene. The reason why the repeating unit composed of ethylene terephthalate or butylene terephthalate is defined as 85% or more is that film formation becomes difficult and the production cost is increased below this.

(A) The thermoplastic polyester is obtained by condensation polymerization of a dicarboxylic acid component and a diol component, the dicarboxylic acid component is made of terephthalic acid, or terephthalic acid and isophthalic acid, and the diol component is made of ethylene glycol and / or butylene glycol. In addition, any of the resins selected from the following (1) to (5) in which the repeating unit composed of ethylene terephthalate or butylene terephthalate is 85% or more by mole percentage is preferable.
(1) Polyethylene terephthalate-polyethylene isophthalate copolymer (2) Polyethylene terephthalate (3) Polybutylene terephthalate-polyethylene terephthalate copolymer (4) Polyethylene terephthalate-polyethylene isophthalate-polybutylene terephthalate copolymer (5) Polybutylene The terephthalate (ii) laminate resin layer is preferably a resin whose main phase is a thermoplastic polyester whose main component is the resin (a) as a basic skeleton, and whose secondary phase is a mixed resin made of polyolefin.

  (Iii) It is preferable that the polyolefin comprises at least one of polyethylene, polypropylene, and ionomer.

  Moreover, it is preferable that the surface orientation coefficient of the surface resin layer of the laminate resin layer is 0.02 or less because the effect on the water vapor treatment is more excellent.

  The resin layer may have a single layer structure made of the aforementioned resin, or may have a multilayer structure and the outermost layer may be made of the aforementioned resin. In the case of a multilayer structure, the resin other than the outermost layer is not particularly limited. The resin on the outer surface side of the can is not limited. A known resin layer may be used. The thickness of the resin layer may be selected according to the application, but generally a thickness of 15 μm or more and 30 μm or less is used. The metal plate is preferably a steel plate or an aluminum plate. As the orientation crystal component increases in the resin, the generation of the groove tends to be suppressed. Therefore, the resin layer of the laminated metal plate is formed by an extrusion method or formed by thermocompression bonding of an unstretched film, or a stretched film. It is preferable to sufficiently melt the oriented crystals by giving a sufficiently high amount of heat when using and laminating.

"Production of laminated steel sheet"
T4CA and TFS (metal chromium layer: 100 to 120 mg / m ² , chromium hydrated oxide layer: 14 to 18 mg / m ² (metal chromium equivalent) having a thickness of 0.23 mm were used as the metal plate. The resin layer was formed by using a film laminating method by thermocompression bonding or an extrusion method, and the film type used for laminating and the laminating method are shown in Table 1. The thickness of the resin layer is 25 μm. Was used.

In Table 1, film types and their melting points are as follows.
PET: Polyethylene terephthalate (257 ° C)
PET-I (14): ethylene terephthalate-ethylene isophthalate copolymer. Isophthalate 14mol% (222 ° C)
PET-I (10): ethylene terephthalate-ethylene isophthalate copolymer. Isophthalate 10mol% (233 ° C)
PET-I (6): ethylene terephthalate-ethylene isophthalate copolymer. Isophthalate 6mol% (244 ° C)
PET-IO: Polyethylene terephthalate-ionomer compound (257 ° C.)
PET-PE: Polyethylene terephthalate-polyethylene compound (257 ° C.)
PET-PP: Polyethylene terephthalate-polypropylene compound (257 ° C.)
PET-PBT (60): ethylene terephthalate-butylene terephthalate copolymer. Butylene terephthalate ratio 60 wt% (247 ° C)
・ PBT: Polybutylene terephthalate (190 ° C)
PET-I (6) -PBT: ethylene terephthalate-ethylene isophthalate-butylene terephthalate copolymer. Mole% ratio (40/6/54) (234 ° C)

The plane orientation coefficient of the produced laminated steel sheet was measured by the following procedure.
"Measurement of plane orientation coefficient"
Using an Abbe refractometer, light source: sodium / D line, intermediate solution: methylene iodide, temperature: 25 ° C., longitudinal refractive index Nx of the film surface, lateral refractive index Ny of the film surface, The refractive index Nz in the thickness direction was measured, and the plane orientation coefficient Ns was calculated by the following formula.
Planar orientation coefficient (Ns) = (Nx + Ny) / 2−Nz
Table 1 shows the plane orientation coefficient of the manufactured laminated steel sheet.

  Moreover, after performing the water vapor process or groove forming process with respect to the produced laminated steel plate on the following conditions, the can manufacturing process (drawing process) was carried out and the metal can was produced.

"Steam treatment"
Water vapor was sprayed on the surface of the steel sheet obtained by heating the prepared laminated steel sheet in the range of 50 to 250 ° C. and treated for 1 minute. The steam treatment conditions are listed in Table 2.

"Can manufacturing (drawing)"
The laminated steel sheet was drawn to produce various cans having a can diameter of 67 mm.
In order to obtain a can with a target drawing ratio, the drawing process was continuously performed 1 to 3 times.
Blank diameter: 112-186mm
Final aperture ratio: 1.67-2.74
About the metal can obtained above, the processing degree was measured, the form of the groove was observed, the amount of the groove was evaluated, and the foaming property was evaluated as follows. Table 2 shows canning process conditions and survey results.

"Measurement of processing degree"
In order to investigate the degree of can processing of the drawn can, the cross-section of the can was polished and subjected to cross-sectional observation. As a result of obtaining the plate thickness at each position of the can body, there was almost no variation in the plate thickness in the circumferential direction of the can, and distribution was confirmed in the plate thickness in the can height direction. Next, the processing degree (%) in the circumferential direction (= peripheral length after processing / peripheral length before processing × 100) was measured for each can height of 10 mm, and the peripheral processing degree by can height was determined.
Here, the peripheral length before processing indicates the peripheral length in a blank plate (circular shape), and the peripheral length after processing indicates the peripheral length in the state after the final molding. As a specific measurement method, a blank plate is marked at intervals of 2 mm in the radial direction and then processed, and the position after processing corresponds to the position before processing. The degree of machining was determined based on the length and the circumference before machining corresponding to the circumference measurement position after the machining.

"Measurement of groove shape and length and groove length"
The dimension and shape of the groove and the total length of the groove (groove density) were measured by the following methods. The measurement was performed using an ER-8800FE electron beam three-dimensional roughness analyzer ERA-8800FE. Measurement was performed at an acceleration voltage of 5 kV and a WD of 15 mm, and the sampling interval in the in-plane direction during measurement was 4 nm. For the calibration in the height direction using this device, the SHS thin film level standard for stylus type and optical surface roughness measuring instruments of VLSI Standard, traceable to NIST, a national research institution in the United States ( Steps of 18 nm, 88 nm, and 450 nm were used. Based on this measurement method, the cross-sectional shape of the groove was determined, and each groove width was measured.

  It was observed that the shape and density of the groove portion in the drawn can had little variation in the circumferential direction and changed according to the height of the can. In addition, the prescribed groove shape was confirmed between a certain degree of processing (above a certain can height) and the top of the can. Therefore, measurement was performed at three locations in the circumferential direction every 10 mm in can height, and the groove shape and groove length for each height were determined. From these results, the total length (groove density) of the groove defined in the invention of claim 1 was calculated on the assumption that there is no bias in the shape and density of the groove in the circumferential direction.

"Bubbling test"
The inner surface of the can body subjected to the heat treatment for strain relief is washed and filled with beer (Kirin lager), and then filled with carbon dioxide gas so that the internal pressure becomes 1 kg / cm ^2. After cooling for 120 hours, the container was opened in a room at 20 ° C., and the foamability of the beer surface after 15 seconds was evaluated according to the following criteria.
Test result: Evaluation foam does not completely cover the liquid level: ×
Foam completely covers the liquid level: ○

(Explanation of Invention Examples and Comparative Examples)
All of the inventive examples were able to obtain good foamability.

  Test cans 19 and 20 are examples in which the steel plate temperature during the steam treatment was lower than the temperature specified in the invention of claim 11. Even if the temperature range of the invention of claim 11 is deviated, it is possible to produce the metal plate for laminated metal cans for beer and sparkling liquor of the present invention by, for example, increasing the processing time. If the conditions are equivalent, the processing effect will be much lower. Therefore, a sufficient groove portion could not be generated in the can making process, and the can body of the present invention could not be produced. In the foamability test, good foaming was not recognized.

  Test cans 21 and 22 are examples in which the can body of the present invention could not be obtained because the degree of processing of the can body was too lower than the scope of the invention of claim 12. In the foamability test, good foaming was not recognized. Depending on the conditions of the steam treatment, it is possible to produce the can of the present invention even at a low workability lower than the scope of the invention of claim 12, but in particular, in the region where the workability is 60% or more as defined in the invention of claim 12. If the area is 25% or more, it is possible to effectively generate a groove. In contrast, the test can 5 has a working degree of the can within the scope of the invention of claim 12 and can secure a groove density within the specified range of the present invention. Good foaming was also observed in the foamability test.

  The metal can of the present invention can be used as a metal can for beer / happoshu that can exhibit good foaming properties when filled with beer / happoshu. The manufacturing method of the metal can of this invention can be utilized as a method of manufacturing the said metal can.

  The laminated metal plate of the present invention can be used as the metal can material. The manufacturing method of the laminated metal plate of this invention can be utilized as a method of manufacturing the said metal plate. The resin film of this invention can be used as resin laminated on the said metal can and the said metal plate. The method for producing a resin film of the present invention can be used as a method for producing the film.

Claims (11)

A metal can having a laminate resin layer on a metal plate on the inner surface side of the can, wherein the laminate resin layer has a groove on its surface, and the groove has a maximum width of 5.0 μm or less in a cross-sectional shape, The groove width is narrower on the steel plate side, the portion where the groove width is 1.0 μm or less in the groove depth direction has a depth of 0.5 μm or more, and the total length of the groove portion per unit area of the inner surface of the can A laminated metal can characterized by having a thickness of 10 mm / mm ² or more and 300 mm / mm ² or less.   2. The laminated metal can according to claim 1, wherein at least the outermost layer of the laminate resin layer is made of a resin mainly composed of a thermoplastic polyester. The thermoplastic polyester resin is obtained by condensation polymerization of a dicarboxylic acid component and a diol component, the dicarboxylic acid component is composed of terephthalic acid, or terephthalic acid and isophthalic acid, the diol component is composed of ethylene glycol and / or butylene glycol, and The repeating unit consisting of ethylene terephthalate or butylene terephthalate is any resin selected from the following (1) to (5) having a molar ratio of 85% or more. Laminated metal can.
(1) Polyethylene terephthalate-polyethylene isophthalate copolymer (2) Polyethylene terephthalate (3) Polybutylene terephthalate-polyethylene terephthalate copolymer (4) Polyethylene terephthalate-polyethylene isophthalate-polybutylene terephthalate copolymer (5) Polybutylene Terephthalate   The laminate resin layer according to claim 2 is a resin whose main phase is a resin whose main phase is a thermoplastic polyester whose main skeleton is the resin according to claim 3 and whose subphase is a mixed resin made of polyolefin. The laminated metal can according to claim 2, wherein   The laminated metal can according to claim 4, wherein the polyolefin is one or more of polyethylene, polypropylene, and ionomer.   The laminated metal can according to any one of claims 1 to 5, wherein a surface orientation coefficient of the surface resin layer of the laminate resin layer is 0.02 or less. The laminate resin layer is laminated metal can according to any of of the preceding claims 1 to 6, characterized in that it is formed by thermocompression bonding the formation or non-oriented film by an extrusion method.   For a film made of a resin having a thermoplastic polyester as a main component on at least one surface, a resin having a thermoplastic polyester as a main component on the outermost layer (the outermost layer on both surfaces has a thermoplastic polyester as a main component) 3. The method for producing a film for a laminated metal can according to claim 1, wherein the film made of the resin is subjected to a treatment of spraying water vapor on the surface of one of the resins.   The method for producing a film for a laminated metal can according to claim 8, wherein water vapor is sprayed on the surface of the film in a state where the film temperature is 80 ° C or higher and not higher than the melting point of the outermost layer resin. The surface of the resin mainly composed of the thermoplastic polyester of the outermost layer with respect to the laminated metal plate having at least one outermost layer made of a resin mainly composed of the thermoplastic polyester on one surface of the metal plate. A metal plate for a laminated metal can produced by spraying water vapor on the outer periphery is defined by the following formula so that the resin whose main component is the outermost thermoplastic polyester is on the inner surface side of the metal can. The method for producing a laminated metal can according to claim 1 or 2, wherein a drawing process is performed so that a region having a direction working degree of 60% or more exists in an area ratio of 1/4 or more of the can body.
Circumferential machining degree (%) = (peripheral length after machining) / (peripheral length before machining) × 100
Here, the circumferential length before processing is the circumferential length of an arbitrary circle centered on the center point of the blank plate, and the circumferential length after processing is the arbitrary circle when the can body is formed. It is a perimeter. The method for producing a laminated metal can according to claim 10, wherein water vapor is sprayed on the laminated metal plate in a state where the temperature of the laminated metal plate is 80 ° C or higher and below the melting point of the outermost layer resin.