JP2011208258A - Aluminum alloy sheet for resin-covered can barrel and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet for a resin-covered can barrel in which moldability is secured while suppressing the reduction of its strength after resin covering to the minimum, and which can improve surface quality of an aluminum can after can barrel molding, and a method for producing the same.SOLUTION: The aluminum alloy sheet for a resin-covered can barrel has a composition comprising, by mass, 0.10 to 0.35% Cu, 0.80 to 1.60% Mg, 0.80 to 1.30% Mn, 0.35 to 0.70% Fe and 0.10 to 0.35% Si, respectively, and the balance Al with inevitable impurities, further, its proof stress after heat treatment at 270°C for 20 s is 225 to 255N/mm, and also, its earing ratio is ≤5%, and regarding the oxygen concentration in the aluminum alloy sheet after cold rolling, the region having ≥10.0 mass% of oxygen lies within 0.08 μm in the sheet thickness direction from the sheet surface.

Description

  The present invention relates to an aluminum alloy plate for a resin-coated can body and a manufacturing method thereof, and in particular, a resin applicable to DI cans and bottle cans (hereinafter referred to as “aluminum cans” when DI cans and bottle cans are collectively referred to). The present invention relates to an aluminum alloy plate for a coated can body and a manufacturing method thereof.

  An aluminum can manufactured from an aluminum alloy plate for a resin-coated can body, for example, a three-piece bottle can is usually manufactured by subjecting an aluminum alloy plate to various forming processes. Specifically, first, a step of forming a thermoplastic resin coating layer on both sides of an aluminum alloy plate and punching out a lubricant coated and obtaining a blank, and then drawing the blank into a cup-shaped molded product And obtaining the step. Next, a step of redrawing and stretching or ironing (DI molding) is performed on the cup-shaped molded product to obtain a bottomed cylindrical can whose body portion is reduced in diameter and thinned. A step of obtaining a can having a mouth part composed of a shoulder part and an unopened part by performing drawing processing a plurality of times on the bottom side of the bottomed cylindrical can. Subsequently, cleaning, trimming, and the like are performed, and then printing and coating are performed on the body portion of the can. Subsequently, the mouth portion is opened to form a curled portion and a screw portion, and the opposite side of the screw portion. After the neck processing and the flange processing are performed on this portion, a step of tightening a bottom lid separately formed by a seamer is performed (for example, see Patent Document 1).

  In recent years, the types of laminated films used for this resin coating are increasing. Along with this, the temperature range for remelting the laminate film in the resin coating step has been expanded, and heat treatment is generally performed in the range of 200 to 280 ° C. (for example, see Patent Document 2). In order to cope with the expansion of the temperature range, there is a demand for an aluminum alloy plate having high heat resistance so that the strength after resin coating does not decrease.

  Therefore, the use of 3004 alloy (3004-H19, stipulated in JIS H4000) subjected to H19 tempering has been proposed for the purpose of minimizing strength reduction after resin coating and improving moldability. Yes. This tempering of H19 is performed by sequentially performing each step of hot rolling and cold rolling on an aluminum alloy sheet. Specifically, an aluminum alloy is melted and cast into an ingot, the surface of the ingot is chamfered, homogenized heat treatment at 570 ° C. to 620 ° C., and then heat at a coiling temperature of 300 ° C. or higher. A method for producing an aluminum alloy plate for a resin-coated can body, in which cold rolling and cold rolling at a rolling rate of 80 to 90% are performed is disclosed (for example, see Patent Document 3).

JP 2001-162344 A (paragraph numbers 0027 to 0028, FIG. 2) JP 2004-238653 A (paragraph number 0032) JP 2006-070344 A (paragraph numbers 0011 to 0015)

  However, in the method for producing an aluminum alloy plate, since a homogenization heat treatment is performed at a high temperature, a thick oxide film is formed on the surface of the aluminum alloy plate. In the case of aluminum cans that are DI molded without resin coating, a new surface appears on the can body during ironing, so the oxide film does not significantly affect the quality of the can body surface. However, in the case of aluminum cans that are DI molded after resin coating, the surface of the base plate and the ironing die surface are not in direct contact, so the effect of the oxide film on the surface of the base plate remains after the can body molding, and the flow mark There was a tendency for surface defects to be noticeable.

  In addition, the required level of aluminum can surface quality does not drop, and it continues to rise in line with market needs. Therefore, even minor surface defects that have not been considered a problem in the past are now regarded as problems, and aluminum cans having such minor surface defects are in the manufacturing process. Is subject to rejection. Therefore, improvement of the surface quality of aluminum cans is an important factor in terms of productivity.

  The present invention has been made to solve the above-mentioned problems, and the problem is that the aluminum can after molding a can body while ensuring moldability while minimizing strength reduction after resin coating. Another object of the present invention is to provide an aluminum alloy plate for a resin-coated can body and a method for producing the same.

  In order to solve the above-mentioned problems, the present inventors have conducted various studies on conditions that can suppress the growth of an oxide film on the surface of an aluminum alloy plate. As a result, after making the contents of Cu, Mg, Mn, Fe and Si appropriate, adjusting the homogenization heat treatment temperature and time, and controlling the conditions of hot rolling and cold rolling, The present inventors have found that the above problems can be solved and have completed the present invention.

That is, the aluminum alloy plate for a resin-coated can body according to the present invention for achieving the above-described object has Cu of 0.10 to 0.35 mass%, Mg of 0.80 to 1.60 mass%, and Mn of 0. .80 to 1.30% by mass, Fe 0.35 to 0.70% by mass, Si 0.10 to 0.35% by mass, the balance being composed of Al and inevitable impurities, 270 An aluminum alloy plate having a yield strength of 225 to 255 N / mm ² after a heat treatment at 20 ° C. for 20 seconds and an ear rate of 5% or less, and the oxygen of the aluminum alloy plate after cold rolling Regarding the concentration, the region of 10.0% by mass or more is characterized by being within 0.08 μm in the plate thickness direction from the plate surface.

  As described above, the aluminum alloy plate for a resin-coated can body according to the present invention can suppress a decrease in strength due to heat treatment after resin coating to a minimum by limiting the components of the aluminum alloy to a specific range. In addition, by limiting the yield strength and ear ratio to a specific range, it can be easily formed into the desired aluminum can shape, and the can strength can be properly maintained even after forming into the aluminum can shape. Become. Furthermore, by limiting the region having an oxygen concentration of a predetermined value or more to a specific range, it is possible to suppress the growth of an oxide film that affects surface defects in the thickness direction from the plate surface of the aluminum alloy plate.

  Moreover, the manufacturing method of the said aluminum alloy plate for resin-coated can bodies which concerns on this invention is Cu 0.10-0.35 mass%, Mg 0.80-1.60 mass%, Mn 0.80. 1. Melting and casting an aluminum alloy containing 1.30% by mass, Fe 0.35 to 0.70% by mass, Si 0.10 to 0.35% by mass, the balance consisting of Al and inevitable impurities A melting / casting step for producing an ingot, a homogenization heat treatment step for subjecting the ingot of the aluminum alloy produced in the melting / casting step to a homogenization heat treatment at 480-540 ° C. for 10 hours or more, and Hot rolling the ingot of the aluminum alloy that has been subjected to the homogenization heat treatment in the homogenization heat treatment step, and winding it at a coiling temperature of 320 ° C. or higher, and hot rolling in the hot rolling step Is given And the aluminum alloy sheet, characterized in that it comprises a cold rolling step of cold rolling to set the rolling ratio in the cold-working 80 to 90% a.

Thus, the method for producing an aluminum alloy plate for a resin-coated can body according to the present invention is such that the temperature of the homogenization heat treatment is limited to a specific range and the plate surface of the aluminum alloy plate is set to be a predetermined time or longer. The growth of the oxide film can be suppressed.
In addition, by making hot rolling / cold rolling a specific condition, an aluminum alloy plate for a resin-coated can body that can maintain the surface quality of the aluminum can after the can body molding sufficiently and has good can characteristics Can be manufactured.

  According to the aluminum alloy plate for resin-coated can bodies and the method for producing the same according to the present invention, it is possible to ensure moldability while minimizing the decrease in strength after resin coating. Moreover, since the growth of the oxide film during the homogenization heat treatment can be minimized, it is possible to provide an aluminum alloy plate for a resin-coated can body excellent in the surface quality of the aluminum can after the can body molding.

It is a perspective view which shows typically a 3 piece bottle can of a prior art. It is a perspective view which shows typically a conventional DI can. A method for producing a three-piece bottle can from a laminate material in which a resin film is coated on the aluminum alloy plate for a resin-coated can barrel, when the aluminum alloy plate for a resin-coated can barrel according to the present invention is evaluated is schematically shown. It is a schematic diagram. (A) is a graph which shows the relationship between the oxygen concentration of the aluminum alloy plate for resin-coated can bodies which concerns on this invention, and the depth from the plate surface. (B) is sectional drawing of the aluminum alloy plate for resin-coated can bodies which concerns on this invention.

  Next, the form for implementing the aluminum alloy plate for resin-coated can bodies and the manufacturing method thereof according to the present invention will be described in detail with reference to the drawings as appropriate.

[Aluminum alloy plate for resin-coated can body]
The resin-coated can body aluminum alloy plate according to the present invention has Cu of 0.10 to 0.35 mass%, Mg of 0.80 to 1.60 mass%, Mn of 0.80 to 1.30 mass%, Fe is contained in an amount of 0.35 to 0.70 mass%, Si is contained in an amount of 0.10 to 0.35 mass%, the balance is composed of Al and inevitable impurities, and heat treatment is performed at 270 ° C. for 20 seconds. The yield strength is 225 to 255 N / mm ² and the ear rate is 5% or less. In addition, in the aluminum alloy plate for a resin-coated can body according to the present invention, the oxygen concentration of the aluminum alloy plate after cold rolling is 10.0% by mass or more in the thickness direction of the aluminum alloy plate. It is within 0.08 μm from the plate surface.
Next, the reasons why the respective alloy components contained in the aluminum alloy plate for resin-coated can bodies according to the present invention, the proof stress after heat treatment and the ear rate, and the oxygen concentration after cold rolling are limited numerically will be described.

(Cu content: 0.10 to 0.35 mass%)
Cu contained in the aluminum alloy plate for a resin-coated can body according to the present invention is an element contributing to material strength. If the Cu content is less than 0.10% by mass, sufficient material strength cannot be obtained, and the yield strength after heat treatment and the screw buckling strength of the molded bottle can are insufficient. On the other hand, if the Cu content exceeds 0.35% by mass, the material strength becomes too high, the proof stress after heat treatment is increased, and the ironing formability is lowered. Therefore, in this invention, content of Cu shall be 0.10-0.35 mass%.

(Mg content: 0.80 to 1.60 mass%)
Mg contained in the aluminum alloy plate for resin-coated can barrels according to the present invention is an element that contributes to material strength as well as Cu described above, and affects the surface quality after can barrel molding. If the Mg content is less than 0.80 mass%, the required material strength cannot be obtained, and the yield strength after heat treatment and the screw buckling strength of the molded bottle can are insufficient. On the other hand, when the Mg content exceeds 1.60% by mass, work hardening increases, the yield strength after heat treatment increases, and ironing moldability decreases. In addition, the oxide film tends to grow during the homogenization heat treatment, and the surface quality of the aluminum can after the can body molding is deteriorated. Therefore, in this invention, content of Mg shall be 0.80-1.60 mass%.

(Mn content: 0.80 to 1.30% by mass)
Mn contained in the aluminum alloy plate for a resin-coated can body according to the present invention is an element that contributes to the material strength like the above-described Mg. When the Mn content is less than 0.80% by mass, sufficient material strength cannot be obtained, and the yield strength after heat treatment and the screw buckling strength of the molded bottle can are insufficient. On the other hand, when the content of Mn exceeds 1.30% by mass, the material strength is excessively increased, which leads to a cylinder cut (breakage during ironing). Therefore, in the present invention, the Mn content is set to 0.80 to 1.30% by mass.

(Fe content: 0.35 to 0.70 mass%)
Fe contained in the aluminum alloy plate for a resin-coated can body according to the present invention affects the recrystallization behavior during hot rolling. When the Fe content is less than 0.35% by mass, recrystallization in the hot rolling process is not sufficiently generated, and coarse crystal grains are mixed and the material strength is increased, and the iron moldability is lowered. On the other hand, if the Fe content exceeds 0.70% by mass, the 0 ° -180 ° ear becomes high, and the dimensional defect of the flange portion (flange portion chipping, etc.) tends to occur. Therefore, in this invention, content of Fe shall be 0.35-0.70 mass%.

Here, the ears are peaks and valleys formed on the side surface of the cylindrical container obtained by cupping with an aluminum alloy plate. The ear rate is calculated using the following equation.
Ear ratio (%) = {(average value of heights at four locations in 45 ° direction based on bottom surface (rolling direction) of cylindrical container−four locations at 0 ° and 90 ° directions based on bottom surface of cylindrical container) Average value of height) / (average value of height of 8 positions in the 0 °, 45 °, and 90 ° directions with respect to the bottom surface of the cylindrical container)} × 100
The “0 ° ear” refers to a mountain formed in a direction of 0 ° with respect to the rolling direction.

(Si content: 0.10 to 0.35 mass%)
Si contained in the aluminum alloy plate for a resin-coated can body according to the present invention affects the recrystallization behavior during hot rolling in the same manner as Fe described above. If the Si content is less than 0.10% by mass, the 0 ° -180 ° ear becomes high, and the dimensional defect of the flange portion is likely to occur. On the other hand, if the Si content exceeds 0.35 mass%, recrystallization in the hot rolling process does not occur sufficiently, and coarse crystal grains are mixed and the material strength is increased, and the ironing formability is lowered. . Therefore, in this invention, content of Si shall be 0.10-0.35 mass%.

(Inevitable impurities)
The aluminum alloy plate for a resin-coated can body of the present invention has, as unavoidable impurities, Cr of 0.1% by mass or less, Zn of 0.5% by mass or less, Ti of 0.3% by mass or less, and Zr of 0. Even if contained in an amount of not more than 0.5% by mass and not more than 0.3% by mass of B, the effect of the present invention is not hindered, and the content of such inevitable impurities is allowed.

(Ti: 0.3% by mass or less)
In the inevitable impurities, Ti and B have an effect of refining the ingot structure. Usually, when adding Ti, the ingot refining agent (TiB) in a ratio of Ti: B = 5: 1 is melted in a waffle-like or rod-like form (melting furnace, inclusion filter, degassing). B added according to the content ratio is inevitably added because it is added to either the apparatus or the molten metal flow rate control apparatus. By adding 0.005 mass% or more as the addition amount of Ti, the crystal grains of the ingot are refined, and the formability of the aluminum alloy plate is improved. For this reason, the Ti content is preferably 0.005% by mass or more, preferably 0.01% by mass or more, and more preferably 0.015% by mass or more. On the other hand, when the content of Ti exceeds 0.3% by mass, a coarse crystallized product is formed and cracks are generated during DI molding, so that the formability of the aluminum alloy plate is lowered. Therefore, the Ti content is 0.3% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0.05% by mass or less.

(Zn: 0.5% by mass or less)
As long as the characteristics of the aluminum alloy plate for resin-coated can bodies of the present invention are not affected, scraps of the aluminum material for brazing sheets may be added (added). In this case, either the upper limit of the prescribed range of Si or the upper limit (0.5% by mass) of the allowable range of Zn described as the inevitable impurities may be added as a guide.

(Yield strength after heat treatment at 270 ° C. for 20 seconds: 225 to 255 N / mm ² )
About formability when performing drawing and ironing after applying resin coating to the aluminum alloy plate, the condition is 270 ° C. for 20 seconds corresponding to heat treatment when resin coating is applied to the aluminum alloy plate. The yield strength after the heat treatment is an important index.

If the proof stress after the aluminum alloy plate is heat-treated at 270 ° C. for 20 seconds is less than 225 N / mm ² , sufficient material strength cannot be obtained, and the screw buckling strength of the molded bottle can is insufficient. On the other hand, when the proof stress exceeds 255 N / mm ² , the moldability of the aluminum can, particularly the iron moldability, is lowered, and the productivity is hindered by the occurrence of breakage. Accordingly, in the aluminum alloy plate for a resin-coated can body according to the present invention, it is preferable that the proof stress after heat treatment at 270 ° C. for 20 seconds is 225 to 255 N / mm ² .

(Ear rate: 5% or less)
The ear ratio of the aluminum alloy plate for a resin-coated can body according to the present invention affects the dimensions of the flange portion. When the ear rate is 5% or more, a dimensional defect of the flange portion is likely to occur remarkably. Therefore, in the aluminum alloy plate for resin-coated can bodies according to the present invention, the ear rate is preferably 5% or less.

(A region where the oxygen concentration is 10.0% by mass or more: within 0.08 μm from the plate surface)
The oxygen concentration on the surface of the aluminum alloy plate for a resin-coated can body according to the present invention affects the surface quality of the aluminum can after the can body molding. This oxygen concentration is measured, for example, by a high-frequency glow discharge luminescent surface analyzer for the aluminum alloy sheet after cold rolling.
The oxygen concentration will be described with reference to FIGS. 4A and 4B. When the oxygen concentration of the aluminum alloy plate is 10.0% by mass or more, the region is within 0.08 μm from the plate surface in the plate thickness direction. (For example, in the case of (a) thick line), there is no noticeable defect on the surface of the aluminum can after the can body molding. On the other hand, when the region where the oxygen concentration is 10.0% by mass or more exceeds 0.08 μm from the plate surface (for example, in the case of (a) fine line), a flow mark-like surface defect is conspicuous after the can body molding. Become. Therefore, in the present invention, the region of 10.0% by mass or more in oxygen concentration is within 0.08 μm from the plate surface.

Next, the manufacturing method of the aluminum alloy plate for resin-coated can bodies according to the present invention will be described.
[Method for producing aluminum alloy sheet for resin-coated can body]
The resin-coated can body aluminum alloy plate according to the present invention is manufactured using an Al-Mn alloy whose alloy composition is regulated in the present invention. That is, Cu is 0.10 to 0.35 mass%, Mg is 0.80 to 1.60 mass%, Mn is 0.80 to 1.30 mass%, Fe is 0.35 to 0.70 mass%, An ingot is produced by DC-casting using an aluminum alloy containing 0.10 to 0.35% by mass of Si and the balance being composed of Al and unavoidable impurities (dissolution / casting). Casting process). The aluminum alloy ingot is subjected to a homogenization heat treatment at 480 to 540 ° C. for 10 hours or more (homogenization heat treatment step), and then the ingot is hot rolled and wound at a winding temperature of 320 ° C. or more. An alloy plate is manufactured (hot rolling process). Subsequently, the aluminum alloy sheet is cold-rolled at a rolling rate of 80 to 90% to obtain a desired sheet thickness (cold rolling process). By setting it as such a manufacturing method, the aluminum alloy plate for resin-coated can bodies which concerns on this invention can be manufactured.

  Next, each condition regulated in the manufacturing method will be described. The reason for limiting the numerical values of the components of the aluminum alloy is omitted because it is the same as the alloy components of the aluminum alloy plate for a resin-coated can body described above.

(Homogenization heat treatment temperature: 480-540 ° C.)
In the method for producing an aluminum alloy plate for a resin-coated can body according to the present invention, if the temperature of the homogenization heat treatment applied to the aluminum alloy plate is less than 480 ° C., recrystallization sufficiently occurs in the subsequent hot rolling step. As a result, coarse crystal grains are mixed and the strength of the material is increased, and the iron moldability is lowered. In addition, the ear rate is increased, and the dimensional defect of the flange portion is likely to occur. On the other hand, if it exceeds 540 ° C., a thick oxide film is formed during the homogenization heat treatment, and the surface quality of the aluminum can after the can body molding is lowered. Accordingly, in the present invention, the temperature of the homogenization heat treatment is set to 480 to 540 ° C.
The homogenization heat treatment of the aluminum alloy plate is usually performed at around 600 ° C. By performing the homogenization heat treatment at a high temperature close to 600 ° C., an Al—Fe—Mn—Si intermetallic compound is appropriately formed. In the case of an aluminum can that is DI-molded without applying a resin coating, the intermetallic compound plays a role of removing aluminum (build-up) deposited between the ironing die and the material during DI molding. As a result, it is possible to suppress wrinkles (seizure) and cracks on the can body surface caused by the accumulated aluminum and to improve iron formability.
When the homogenization heat treatment temperature is a low temperature (480 to 540 ° C.) regulated by the present invention, the intermetallic compound is not sufficiently formed, but for the aluminum can of the DI molding after applying the resin coating, Since the ironing die and the material are not in direct contact, the formation of the intermetallic compound is not essential. Therefore, in the aluminum alloy plate for a resin-coated can body according to the present invention, the temperature of the homogenization heat treatment is set to the above temperature range (480 to 540 ° C.) in order to improve the surface quality after the can body molding as described above. did.

(Homogenization heat treatment time: 10 hours or more)
In the method for producing an aluminum alloy plate for a resin-coated can body according to the present invention, if the time of the homogenization heat treatment applied to the aluminum alloy plate is less than 10 hours, a lot of fine precipitates that inhibit recrystallization are distributed, Sufficient recrystallization does not occur during hot rolling. As a result, coexistence of coarse crystal grains and an increase in material strength occur, resulting in a decrease in iron moldability. In addition, the ear rate is increased, and the dimensional defect of the flange portion is likely to occur. Therefore, in the present invention, the time for the homogenization heat treatment is set to 10 hours or more.

(Taking-up temperature in the hot rolling process: 320 ° C. or more)
In the method for producing an aluminum alloy plate for a resin-coated can body according to the present invention, the coiling temperature in the hot rolling step applied to the aluminum alloy plate affects the recrystallization state of the hot coil and also affects the material strength. It is an important factor to give.

  That is, if the coiling temperature of the hot rolling process is less than 320 ° C., recrystallization in the aluminum alloy plate does not occur sufficiently, resulting in the mixing of coarse crystal grains and an increase in material strength, and ironing forming. Sex is reduced. In addition, the ear rate is increased, and the dimensional defect of the flange portion is likely to occur. Therefore, the coiling temperature of hot rolling in the method for producing an aluminum alloy plate for a resin-coated can body according to the present invention needs to be 320 ° C. or higher.

(Rolling ratio of cold working: 80-90%)
The rolling rate of cold working included in the method for producing an aluminum alloy plate for a resin-coated can body according to the present invention is a factor contributing to material strength and formability. That is, if the rolling ratio of this cold working is lower than 80%, sufficient material strength cannot be obtained, and the yield strength after heat treatment and the screw buckling strength of the molded bottle can are insufficient. Further, the 0 ° -180 ° ear becomes high, and the dimensional defect of the flange portion is likely to occur. Moreover, when the rolling rate of this cold working exceeds 90%, the yield strength becomes high and the ear rate becomes excessively high, which tends to cause a dimensional defect of the flange portion. Therefore, in this invention, it is required that the rolling rate of cold work is 80 to 90%.

  The above-described aluminum alloy plate for a resin-coated can body according to the present invention is suitable for a conventional one-piece three-piece bottle can as shown in FIG. 1, a conventional example DI can as shown in FIG. At the same time, it is also a suitable material for various conventional aluminum alloy laminates.

  When the resin-coated can body aluminum alloy plate according to the present invention is applied to a conventional three-piece bottle can 1 as shown in FIG. 1, the resin-coated can body aluminum alloy plate according to the present invention is used. On the other hand, can body molding such as cup molding and DI molding is performed to form a bottomed cylindrical can (body portion 2). Subsequently, the neck portion 3 is formed by necking the bottom portion of the bottomed cylindrical can.

  The neck portion 3 of the three-piece bottle can 1 shown in FIG. 1 is provided with a threaded portion by being threaded for attaching a cap after the mouth portion 4 is opened. In addition, the opening (not shown) facing this is subjected to neck processing and flange processing, and then a bottom lid 5 separately formed by a seamer is wound up, whereby the three-piece bottle can 1 can be manufactured.

  When the aluminum alloy plate for a resin-coated can body according to the present invention is applied to a conventional general DI can 11 as shown in FIG. 2, the aluminum alloy plate for a resin-coated can body according to the present invention is used. On the other hand, the body 12 is formed by subjecting the can body such as cup molding or DI molding. Subsequently, necking 13 is performed on the body portion 12 to form a neck portion 13. Subsequently, an opening portion 14 is formed at the end portion of the neck portion 13, and the diameter of the opening portion 14 is set to the diameter of the body portion 12. The DI can 11 can be manufactured by processing so as to be smaller.

  In addition, when the aluminum alloy plate for resin-coated can bodies according to the present invention is applied to a conventional general laminate material, various resin films applied to a conventionally known laminate material are bonded with an adhesive or the like. Then, a laminate material is manufactured through a process in which heat treatment is performed at a temperature equal to or higher than the melting point of the resin film.

  Next, the resin-coated can body aluminum alloy plate according to the present invention and the manufacturing method thereof will be described in detail by comparing an example satisfying the requirements of the present invention with a comparative example not satisfying the requirements of the present invention.

  First, an aluminum alloy having an alloy composition as shown in Table 1 was melted and cast, and this ingot was subjected to homogenization heat treatment at the homogenization heat treatment temperature and time shown in Table 1. Subsequently, hot rough rolling and hot finish rolling were sequentially performed to produce a hot rolled plate, and then the hot rolled plate was wound at a winding temperature as shown in Table 1 to obtain a hot coil. And this hot coil was cold-rolled with the processing rate shown in Table 1, and it was set as the 0.32 mm-thick aluminum alloy plate for resin-coated can bodies.

  Moreover, the oxygen concentration of the plate surface was measured with respect to the aluminum alloy plate for the resin-coated can body using a high-frequency glow discharge light emitting surface analyzer (JY5000RF, manufactured by Horiba, Ltd.). Was determined to be 10.0 mass%.

  Further, the aluminum alloy plate for the resin-coated can barrel was subjected to a heat treatment at 270 ° C. for 20 seconds, which is almost the same as the heat treatment at the time of resin coating, using a nitrite furnace (a salt bath), and then JIS Z The measurement result obtained by measuring the yield strength (0.2% yield strength) according to 2241 was taken as the yield strength after heat treatment.

Then, using the resin-coated can body aluminum alloy plate, a φ66.7 mm blank was prepared, and this blank was squeezed with a φ40 mm punch to prepare a cup. Using this cup, measurement was performed in accordance with a method for measuring ear rate described later, and the obtained measurement result was defined as ear rate.
Ear ratio (%) = {(average value of heights at four locations in 45 ° direction based on bottom surface (rolling direction) of cylindrical container−four locations at 0 ° and 90 ° directions based on bottom surface of cylindrical container) Average value of height) / (average value of height of 8 positions in the 0 °, 45 °, and 90 ° directions with respect to the bottom surface of the cylindrical container)} × 100

  Examples 1 to 6 all satisfy the conditions regulated by the present invention.

  In Comparative Example 1, the Cu content is less than the lower limit of the range numerically limited in the present invention, and the proof stress after heat treatment is less than the lower limit of the numerically limited range. In Comparative Example 2, the Cu content exceeds the upper limit of the range numerically limited in the present invention, and the proof stress after the heat treatment exceeds the upper limit of the numerically limited range.

  In Comparative Example 3, the Mg content is less than the lower limit of the range numerically limited in the present invention, and the proof stress after heat treatment is less than the lower limit of the numerically limited range. In Comparative Example 4, the Mg content exceeded the upper limit of the range numerically limited in the present invention, the proof stress after the heat treatment exceeded the upper limit of the numerically limited range, and oxygen after cold rolling The density exceeds the upper limit of the range limited in numerical values.

In Comparative Example 5, the content of Mn is less than the lower limit value of the range numerically limited in the present invention, and the proof stress after the heat treatment is less than the lower limit value of the numerically limited range. In Comparative Example 6, the Mn content exceeds the upper limit of the range numerically limited in the present invention, and the proof stress after the heat treatment exceeds the upper limit of the numerically limited range.

In Comparative Example 7, the Fe content is less than the lower limit value of the range numerically limited in the present invention, the proof stress after the heat treatment exceeds the upper limit value of the numerically limited range, and the ear rate is numerically limited. The upper limit of the specified range is exceeded. In Comparative Example 8, the Fe content exceeded the upper limit of the range numerically limited in the present invention.

In Comparative Example 9, the Si content is less than the lower limit value of the range numerically limited in the present invention. In Comparative Example 10, the Si content exceeded the upper limit value of the range numerically limited in the present invention, and the proof stress after the heat treatment exceeded the upper limit value of the numerically limited range. Exceeds the upper limit of the numerically limited range.

In Comparative Example 11, the temperature of the homogenization heat treatment is less than the lower limit of the range numerically limited in the present invention, the proof stress after the heat treatment exceeds the upper limit of the numerically limited range, and the ear ratio is a numerical value. The upper limit of the limited range is exceeded. In Comparative Example 12, the temperature of the homogenizing heat treatment exceeds the upper limit value of the range limited by the present invention, and the oxygen concentration after cold rolling exceeds the upper limit value of the numerically limited range.

In Comparative Example 13, the homogenization heat treatment time is less than the lower limit value of the range numerically limited in the present invention, the proof stress after the heat treatment exceeds the upper limit value of the numerically limited range, and the ear ratio is a numerical value. The upper limit of the limited range is exceeded.

  In Comparative Example 14, the coiling temperature in the hot rolling is less than the lower limit value of the range numerically limited in the present invention, and the proof stress after the heat treatment exceeds the upper limit value of the numerically limited range. The rate exceeds the upper limit of the numerically limited range.

  In Comparative Example 15, the cold rolling rate in the cold rolling step is less than the lower limit value of the range numerically limited in the present invention, and the proof stress after the heat treatment is less than the lower limit value of the numerically limited range. In Comparative Example 16, the cold rolling rate exceeds the upper limit value of the range numerically limited in the present invention, the proof stress after the heat treatment exceeds the upper limit value of the numerically limited range, and the ear rate is numerically limited. The upper limit of the specified range is exceeded.

  The aluminum alloy plates for resin-coated can bodies of Examples 1 to 6 according to the present invention and Comparative Examples 1 to 16 that do not satisfy the conditions regulated by the present invention were subjected to alkali cleaning and phosphoric acid chromate treatment. After that, a resin film having a thickness of 16 μm was coated on both surfaces, and further heat-treated at 270 ° C. for 20 seconds to obtain a laminate material. Hereinafter, with reference to FIG. 3, the evaluation method performed about the said laminate material is demonstrated. FIG. 3 shows a method for producing a three-piece bottle can from a laminate material in which a resin film is coated on the aluminum alloy plate for a resin-coated can barrel when evaluating the aluminum alloy plate for a resin-coated can barrel according to the present invention. It is a schematic diagram shown typically.

  Cup molding was performed using the laminate material 21 to produce a cup 22. In general, when the laminate material of an aluminum alloy plate is squeezed up to the opening as in conventional normal DI molding, the resin film peels off at the tip of this upper end or builds up on a die, etc. Processing defects are likely to occur. For this reason, in the present invention, the laminate material 21 manufactured from the aluminum alloy plate is formed without leaving the flange portion 22a as appropriate, without squeezing the tip of the upper end portion as in the conventional normal DI molding.

  In the molding evaluation of the laminate material, white petrolatum was applied after cup molding, drawing molding and ironing molding (DI molding), and necking and threading were performed on the bottom of the obtained aluminum can. In DI molding, molding was performed with the flange portion 22a remaining in order to suppress peeling of the coated resin film. And after giving neck processing and flange processing to the obtained aluminum can, the separately formed bottom cover 5 was wound and the 3 piece bottle can 1 was produced.

(Silent formability)
As for ironing moldability, when 10000 cans can be made by continuous molding, the number of breaks (out of body) is 0 to 3 times “good (good)”, 4 times or more “× ( Bad) ”.

(Flange dimensions)
For the flange dimensions, “○ (good)” indicates that the shape of the flange 22a remaining at the upper end during ironing is close to a perfect circle, and “× (defective) indicates that the square or flange 22a is missing. "

(Surface quality)
In the can after trimming, visually observe the upper end in the 90 ° direction with respect to the rolling direction of the plate, and mark “◯ (good)” if there are 3 or less flow-marked black streaks in the range of 20 mm from the upper end. Four or more were designated as “x (defect)”.

(Screw buckling strength)
A compression load in the axial direction was applied to the molded three-piece bottle can 1, and the load when the screw portion buckled was measured for five samples, and the average value was defined as the screw buckling strength. In addition, since there is no practical problem if the screw buckling strength is 1500 N or more, those having 1500 N or more were rated “good” and those having less than 1500 N were “x (defect)”.
The above evaluation results are shown in Table 2.

  As shown in Table 2, in the examples (Examples 1 to 6) that satisfy all the conditions regulated by the present invention, all of the evaluation items (ironing formability, flange part size, surface quality, screw buckling strength) are obtained. The result was satisfactory. On the other hand, in the comparative examples (Comparative Examples 1 to 16) that do not satisfy the conditions regulated by the present invention, those that satisfactorily satisfy all the evaluation items were not obtained.

  In Comparative Example 1, the screw buckling strength did not reach a practically satisfactory level, and in Comparative Example 2, the ironing formability was “x (defect)”. Further, Comparative Example 3 does not reach a practically satisfactory level of screw buckling strength, and Comparative Example 4 has an iron moldability of “x (defect)” and a surface quality of “x (defect)”. there were.

  In Comparative Example 5, the screw buckling strength did not reach a practically satisfactory level, and in Comparative Example 6, the ironing formability was “x (defect)”. In Comparative Example 7, the ironing formability and the flange part dimensions were “x (defect)”, and in Comparative Example 8, the flange part dimensions were “x (defect)”.

  In Comparative Example 9, the dimension of the flange portion was “x (defect)”, and in Comparative Example 10, the ironing formability and the flange portion dimension were “x (defect)”.

  In Comparative Example 11, the ironing formability and the flange size were “x (defect)”, and in Comparative Example 12, the surface quality was “x (defect)”. Further, Comparative Example 13 and Comparative Example 14 were “× (defect)” in the ironing formability and the flange portion dimensions.

  In Comparative Example 15, the flange part dimension was “x (defect)”, and in Comparative Example 16, the ironing formability and the flange part dimension were “x (defect)”.

  In addition, the aluminum alloy plate of the comparative example 12 assumes the conventional aluminum alloy plate described in the patent document. As shown in this example, this conventional aluminum alloy sheet does not satisfy a certain level of surface quality. Therefore, this example objectively revealed that the aluminum alloy plate according to the present invention is superior to the conventional aluminum alloy plate.

DESCRIPTION OF SYMBOLS 1 3 piece bottle can 2 Body part 3 Neck part 4 Mouth part 5 Bottom cover 11 DI can 12 Body part 13 Neck part 14 Opening part 21 Laminating material 22 Cup 22a Flange part

Claims (2)

Cu is 0.10 to 0.35 mass%, Mg is 0.80 to 1.60 mass%, Mn is 0.80 to 1.30 mass%, Fe is 0.35 to 0.70 mass%, Si is Each containing 0.10 to 0.35% by mass, the balance being composed of Al and inevitable impurities, and the yield strength after heat treatment at 270 ° C. for 20 seconds is 225 to 255 N / mm ² , and An aluminum alloy plate having an ear rate of 5% or less,
An aluminum alloy plate for a resin-coated can body, characterized in that the oxygen concentration of the aluminum alloy plate after cold rolling is 10.0% by mass or more within 0.08 μm in the plate thickness direction from the plate surface . Cu is 0.10 to 0.35 mass%, Mg is 0.80 to 1.60 mass%, Mn is 0.80 to 1.30 mass%, Fe is 0.35 to 0.70 mass%, Si is A melting / casting step for producing an ingot by melting and casting an aluminum alloy containing 0.10 to 0.35% by mass and the balance being composed of Al and inevitable impurities;
A homogenization heat treatment step of subjecting the ingot of the aluminum alloy produced in the melting / casting step to a homogenization heat treatment at 480 to 540 ° C. for 10 hours or more;
Hot rolling the ingot of the aluminum alloy that has been subjected to the homogenization heat treatment in the homogenization heat treatment step, and winding the coil at a coiling temperature of 320 ° C. or higher; and
A cold rolling process in which the aluminum alloy sheet that has been hot-rolled in the hot-rolling process is cold-rolled by setting a rolling rate of cold working to 80 to 90%;
The manufacturing method of the aluminum alloy plate for resin-coated can bodies characterized by including.

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