JPH03215645A - Aluminum alloy for fluororesin coated container and its manufacture - Google Patents

Abstract

PURPOSE:To improve the formability and adhesion for fluororesin in an Al alloy for a fluororesin coated container by subjecting an Al alloy having specified content of Mn and Mg to homogenizing treatment, holding it to a low temp., thereafter reheating the Al alloy and executing rolling. CONSTITUTION:An alloy contg., by weight, 0.2 to 2.0% Mn and 0.01 to <0.2% Mg, or furthermore contg. 0.01 to 0.2% Cu and <=2.0% total of Fe and Si, satisfying <=5 Fe/Si and the balance Al with inevitable impurities is cast. This alloy is subjected to homogenizing treatment at >=450 deg.C for >=1hr and is held to a temp. lower than the above treating temp. by >=20 deg.C for >=30min. The alloy is cooled, is thereafter heated to >=400 deg.C and is subjected to hot rolling and cold rolling. In this way, the Al alloy for a fluororesin coated container excellent in adhesion for fluororesin and formability and having a good appearance after etching treatment can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aluminum alloy for fluororesin-coated containers that has excellent moldability and fluororesin adhesion, and a method for producing the same.

[Conventional technology and its issues]

Fluorine resin has excellent water resistance and heat resistance, so it is coated on aluminum and aluminum alloys and used in frying pans, inner pots of rice cookers, etc.

In order to improve resin adhesion, the fluorocarbon resin coating material for such uses is made by uniformly roughening the surface of a base material such as aluminum or aluminum alloy by chemical or electrochemical enoching or the like. After that, fluorine resin is applied and molded.

Conventionally, AA1100, 1050, 3004 alloys, etc. have been used as aluminum alloys for the above-mentioned plastic-coated containers.

When pure AN-based materials such as AAIIOO and 1050 are used, it is difficult to obtain a uniformly roughened surface by chemical or electrochemical enoching, and the adhesion of the fluororesin tends to vary. In addition, due to variations in a series of manufacturing conditions, there is a problem in that the moldability after fluororesin coating deteriorates, and the selvage rate increases in deep drawing.

On the other hand, when an Al-Mn-Mg system such as 4A3004 is used, it is difficult to obtain a uniform rough surface by chemical or electrochemical enoting, and variations in the adhesion of the phenolic resin occur. In addition to being easy to use, subtle differences in casting conditions can cause non-uniformity in the weave, resulting in etching patterns such as stripes and streaks on the surface of the plate after etching, which impairs the appearance of the product. Furthermore, since the content of Mg and Mn is high, the amount of work hardening during molding is large, making it unsuitable for redrawing or spinning.

[Problems to be Solved by the Invention] In view of the above, as a result of various studies, the present invention provides an aluminum alloy for fluorocarbon resin-coated containers that has excellent adhesion to fluorine resin and excellent moldability, and a method for producing the same. It was developed.

[Means and effects for solving the problem] The present invention provides M
n0.2-2.0wt%, Mg0.01-0.2w
It is an aluminum alloy for containers coated with fluorine resin, which contains less than t% and the balance is Al and unavoidable impurities.
no. 2-2.0wt%, Mg0.01-0.2wt
Less than %Cu0.01~0.2wt%, Fe and Si
Contains 2.0 wt% or less in total, and the Fe, Si amount ratio (
It is an aluminum alloy for fluorine-resin coated containers with Fe/Si) of 5 or less and the remainder consisting of Al and unavoidable impurities, with Mn 0.2 to 2.0 wt%, Mg 0.0
Aluminum alloy containing less than 1 to 0.2 wt% and the remainder A2 and unavoidable impurities or Mn0.2 to 2. O
wL%, Mg o. ox~less than 0.2wt%, Cu0.
01-0.2wt%, total of Fe and Si 2.0w
t% or less, the Fe, Si amount ratio (Fe/Si) is 5 or less, and the remainder is AI! After homogenizing an aluminum alloy consisting of aluminum and inevitable impurities at a temperature of 450°C or higher for 1 hour or more, it is held at a temperature 20°C or more lower than the homogenization temperature for 30 minutes or more, and after cooling, it is heated again to 400°C or higher. This is a method for producing an aluminum alloy for a container coated with a fluorocarbon resin, which is characterized in that hot rolling and cold rolling are performed after heating to .

That is, the present invention is an aluminum alloy in which the strength is improved without reducing formability by adding a small amount of Mn to A2, and the strength and deep drawability are improved by adding Mg. This is an aluminum alloy in which the strength is improved by adding a small amount of Cu to the above alloy, and the enoting property is improved by controlling the content of Fe and Si. The present invention also provides Aj! of the above-mentioned alloys. -Recrystallized grains of Mn-based precipitates are made finer, resulting in poor appearance during molding,
This is a method for producing an aluminum alloy that does not cause uneven enoching.

In the present invention, the alloy composition is limited for the following reason.

By adding Mn to Af, strength is improved without reducing moldability. The amount added is 0.2~
The reason why it is set at 2.0 wt% is because strength is low if it is less than 0.2 wt%. This is because if it exceeds Qwt%, the effect will be saturated and the formability will decrease.Mg improves the strength by adding it to Al. Furthermore, when added to an Af-Mn alloy, the anisotropy of the material decreases, lowering the selvage ratio during deep drawing. The amount added is 0.01~0.2wt
The reason why the content is less than 0.01 wt% is that the effect is small, and if it is less than 0.2 wt%, the effect is saturated and the moldability is reduced.

Cu improves material strength by adding it to A2, and the amount of Cu added is 0.01 to Q. The reason why it is set at 2wt% is because the effect is small if it is less than 0.01wt%.
If it exceeds wt%, 45° ears will develop during deep drawing,
The selvage rate increases, and it becomes difficult to set appropriate enoching conditions, making it impossible to obtain a uniform rough surface. Fe, Si is A
It is contained as an impurity in 2. Fe and S
If the total amount of i exceeds 2.0iit%, the etching properties will be reduced, a uniform rough surface will not be obtained, and the moldability will also be reduced. Furthermore, when the ratio of Fe to Si (Fe/St) exceeds 5, the etching performance decreases.

Note that Ti, which is usually added as a refiner for the casting structure,
If B and the like are added in an amount of 0.1 wt% or less, the effects of the present invention will not be particularly impaired.

Next, the manufacturing process will be explained.

The precipitation and solid solution state during homogenization affect the properties of the final plate, such as the edge ratio and recrystallization behavior. In the alloy according to the invention,
Under normal homogenization treatment conditions, fine and dense AA-Mn-based precipitates are formed, and movement of grain boundaries is obstructed during recrystallization of the rolled sheet, resulting in coarse crystal grains. Such a coarse grain structure results in poor appearance such as rough skin during deep drawing. By reheating after homogenization treatment as in the production method of the present invention, relatively large precipitates are formed, and the recrystallized grains of the rolled plate are fine, so that poor appearance during forming and uneven enoching do not occur. . The reason why the homogenization treatment condition is maintained at 450° C. or higher for 1 hour or more is because if the temperature is lower than 450° C. or for less than 1 hour, the growth of precipitates will be insufficient and a coarse grain structure will result. In addition, after the homogenization process, 2
The reason for holding at a temperature lower than 0″C for 30 minutes or more is as follows.
If the temperature is 20"C for less than 30 minutes, the precipitates will not grow sufficiently. If the temperature is kept below 350°C, the precipitates will not grow sufficiently.

Annealing treatment after hot rolling is done to make the crystal grains finer and
This is a process performed to make it uniform. This annealing may be performed by punch annealing or continuous annealing. The temperature is 30
The reason for setting the temperature to be 0°C or higher is that recrystallization is not completed below 300°C. Note that the annealing treatment time may be appropriately determined depending on the annealing temperature.

The plate material produced by the above manufacturing process is cold rolled to a predetermined thickness, annealed, coated with fluorine resin, and then molded. Note that the effects of the present invention will not be impaired whether the final annealing is performed by batch annealing or continuous annealing.

〔Example〕 An embodiment of the present invention will be described below.

Example 1 AI with the composition shown in Table 1! ．． The alloy was melted in a conventional manner and cast by DC casting to obtain an ingot with a thickness of 150 mm, a width of 500 mm, and a length of 500 m. After face milling, this was homogenized at 580''C for 5 hours, held at 500°C for 3 hours, and cooled to room temperature. Thereafter, it was reheated to 500°C and hot rolled.

Here, annealing was performed at 400° C. for 2 hours, and a plate material having a thickness of 2 m was obtained by cold rolling, and final annealing was performed.

Ta.

The surface of this plate was roughened by conventional electrochemical etching. That is, etching was performed in a 5% ammonium chloride aqueous solution (25°C) by passing a direct current at a current density of 20 A/dn+''.Thereafter, the fluororesin was coated to a thickness of 401 mm.This fluororesin coated board The tensile strength, deep-drawn selvage ratio, appearance, and coating film adhesion were measured.The results are shown in Table 2.

Table 2 Tensile strength was measured by conducting a tensile test using a JIS No. 5 tensile test piece.

The deep drawing edge ratio was measured by applying lubricating oil to a φ57 ma+ blank and deep drawing with a φ33 punch (drawing ratio 1.73). 0-90° ears (+ ears), 45° ears (~
Ear) It was judged as good if it was 2% or less in any direction.

Appearance is ○ if there are no etching patterns such as stripes or lines when visually inspected, Δ if there are slight etching patterns such as stripes or lines, and it is so marked that it cannot be used as a product. Those in which etching patterns such as stripes were present are marked as ×.

Paint film adhesion was evaluated by Erichsen-base test. In other words, 11 parallel line scratches perpendicular to the paint are defined as l[I
III Attach at intervals of 1, and overhang molding (overhang height 5
m) was carried out. Paste sellotape on the base part,
After peeling off, the number of squares remaining without peeling off the coating film was measured.

As is clear from Table 2, the alloys a to d of the present invention are excellent in tensile strength, edge ratio, appearance, and adhesion.

Comparative alloy compositions e-j and conventional alloy compositions k-n, which are outside the alloy composition of the present invention, are inferior in any one or more of tensile strength, deep-drawn edge ratio, appearance after enoching, and coating film adhesion.

Example 2 Af alloys with compositions a and c shown in Table 1 were melted by a conventional method and DC
Thickness: 150mm, width: 50mm, length: 500mm by casting
An ingot of 01111 was obtained. After face-cutting, the material was homogenized and reheated as shown in Table 3, then hot rolled and cold rolled into a plate material with a thickness of 2 holes, and final annealed.

Similar to Example 1, this plate material was subjected to surface roughening treatment by electrochemical etching and coating with fluorine resin, and its tensile strength, deep draw edge ratio, appearance, coating, and coating film adhesion were measured. 3rd result
Also listed in the table.

As is clear from Table 3, the production method Nαl~4 of the present invention
The material is excellent in tensile strength, selvage ratio, appearance, and adhesion. Comparative production method seeds 5 to 9 that deviate from the production method of the present invention are:
Poor in one or more of deep-drawn edge ratio, appearance after etching, and paint film adhesion.

Example 3 Affi alloys having compositions a and c shown in Table 1 were melted by a conventional method.
Thickness 150mm, width 500mm, length 5 by DC casting
A 00 mm ingot was obtained. After facing this, it was heated to 580℃ for 5
After homogenization for 3 hours, the mixture was kept at 500° C. for 3 hours and cooled to room temperature. Thereafter, it was reheated to 500°C and hot rolled. This was subjected to annealing treatment under the conditions shown in Table 4, and then cold rolled into a plate material with a thickness of 2 m, and final annealing was performed.

Similar to Example 1, this plate material was subjected to surface roughening treatment using electrochemical etching and coating with fluorine resin, and its tensile strength, deep draw edge ratio, appearance, and coating film adhesion were measured. The results are also listed in Table 4.

As is clear from Table 4, Nα obtained by the production method of the present invention
Samples Nos. 11 and 12 are excellent in tensile strength, edge ratio, appearance, and adhesion. Comparative manufacturing method Nα13-1 that deviates from the manufacturing method of the present invention
Sample No. 4 is inferior in at least one of the deep-drawn selvedge ratio, the appearance after enoching, and the coating adhesion.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain an aluminum alloy for use in containers coated with plastic resin, which has excellent adhesion to plastic resin and molding processability, and also has a good appearance after etching treatment, and is industrially outstanding. It is effective.

Claims (4)

[Claims] (1) Mn0.2-2.0wt%, Mg0.01-0.
An aluminum alloy for fluororesin-coated containers, containing less than 2 wt%, with the remainder being Al and unavoidable impurities. (2) Mn0.2-2.0wt%, Mg0.01-0.
Contains less than 2 wt%, Cu 0.01 to 0.2 wt%, Fe and Si in total of 2.0 wt% or less, Fe and Si ratio (Fe/Si) is 5 or less, and the remainder consists of Al and inevitable impurities. Aluminum alloy for fluororesin-coated containers. (3) Mn0.2-2.0wt%, Mg0.01-0.
Aluminum alloy containing less than 2 wt% and the balance consisting of Al and unavoidable impurities or Mn0.2 to 2.0 wt%, M
g0.01~less than 0.2wt%, Cu0.01~0.2
An aluminum alloy containing a total of 2.0 wt% or less of Fe and Si and a Fe/Si ratio (Fe/Si) of 5 or less, with the remainder being Al and unavoidable impurities.
After performing homogenization treatment at a temperature of 0°C or more for 1 hour or more, the temperature is maintained at a temperature 20°C or more lower than the homogenization treatment temperature for 30 minutes or more, and after cooling, the temperature is heated again to 400°C or more, followed by hot rolling. A method for producing an aluminum alloy for fluororesin-coated containers, the method comprising cold rolling. (4) The method for producing an aluminum alloy for fluororesin-coated containers according to claim 3, characterized in that annealing treatment is performed at a temperature of 300° C. or higher between hot rolling and cold rolling.