JPH02147107A - Manufacture of aluminum foil base material - Google Patents

Abstract

PURPOSE:To reduce the number of generated pin holes by hot rolling an Al alloy ingot containing Fe and Si of respective specific contents and then performing alkali washing with an alkaline solution of a specific pH value for a period of specific seconds before a cold rolling ratio exceeds a specific value in cold rolling. CONSTITUTION:An Al alloy ingot containing, by wt., 0.1-1.0% Fe and <=0.5% Si is hot rolled and then the ingot is cold rolled; the stock is washed with an alkaline solution of >=10pH for 1-100sec before a cold rolling ratio exceeds 96%. Fe content has effects of increasing strength and of grain refinement; when the content exceeds 0.1%, corrosion resistance is reduced. Si content has large solid solubility and the content is desirable to be small for acceleration of rolling effect, but it is inevitably contained in Al base material and is limited to <=0.5% which is a reducible amount as Al-Fe-Si base compound with after processing. Fe and Si are limited to the above composition range to reduce metal structurally the generation number of pin holes because Fe and Si are contained in Al base material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing aluminum foil, particularly an aluminum foil having a foil thickness of 25 μm or less and having few pinholes.

[Conventional technology]

In general, aluminum foil substrates vary depending on the application, but those with a thickness of 5.0 to 200 μm are often used, and are usually made of Cu.
O, 04W1% or less (hereinafter wt% is simply abbreviated as %), S
i0.2% or less, FeO, 25% or less, Mn0.
03% or less, Mg O, 03% or less, 2n O, 0
51070 alloy with 4% or less, Ti Q, 03%, AI 99.7% or more, Cu O, 10% or less, S
i+Fe O, 7% or less, ! 11710.05% or less, 2nO 105% or less, Al 99.3% or more 5IN per month
30 alloy, CuO, 05-0.20%, 5O46%
Below, Fe-0.7% or less, Mn 1. Q ~1.
5%.

2nO, 10% or less, residual heat ^! Its 3003 alloy, etc., is made by homogenizing the ingot, then hot rolling, and then cold rolling and foil annealing. However, when the foil thickness is 25 μm or less, the occurrence of peen holes cannot be avoided and there is a drawback that the moisture permeability (air permeability) increases, which is a major problem depending on the application.

In recent years, various methods have been proposed for producing aluminum foil substrates with fewer pinholes, including controlling the alloy components and manufacturing process to create a metal structure in the foil substrate with fewer pinholes. .

['Problem to be solved by the invention]

Specifically, the metallographic structure is controlled by controlling the amount of elements dissolved in the foil base and preventing the precipitation of elemental Si, but pinholes occur in thin foils that are rolled in layers. It is not possible to completely prevent the occurrence of

[Means for solving problems]

In view of this, as a result of various studies, the present invention has developed a method for manufacturing an aluminum foil base with fewer pinholes.
When hot rolling an Al alloy ingot containing FeQ, 1 = 1.0% and SiO, 5% or less, and then cold rolling, the pH is adjusted to 10 before the cold rolling rate exceeds 96%.
It is characterized by carrying out alkaline cleaning with the above alkaline solution for 1 to 100 seconds. That is, the present invention
This is based on the following knowledge obtained through systematic research on the occurrence of pinholes in foil.

When we investigated what types of pinholes are that cannot be prevented by controlling the metallographic structure mentioned above, we found that they occur where the corrugated foil on the mating surface becomes particularly thin during overlapping rolling. Pinholes do not occur if the mating surfaces are simply undulating; minute scratches occur on the surface of the foil before rolling, and pinholes do not occur until the scratches correspond to the areas thinned by the corrugation. It was found that holes were formed. Therefore, in order to prevent this type of pinhole, it is necessary to prevent waving during overlapping rolling or to create a foil with fewer minute scratches before overlapping rolling. However, the former phenomenon is unique to foil rolling and is difficult to prevent.

The present invention is based on a series of researches on the occurrence of microscopic scratches.
The main cause of minute scratches is iron powder of about 05 to 10 μm that adheres to the surface of the foil during hot rolling during the production of the foil, and this iron powder changes the state of the aluminum coating on the surface of the foil rolling roll, causing the foil to deteriorate. It was found that this causes minute scratches. Therefore, the present invention investigated a method for removing this iron powder and developed the production method of the present invention.

[Effect]

In the present invention, the Fe content is limited to 0.1 to 1.0% because Fe has the effect of increasing strength appropriately and refining crystal grains, and also has the effect of softening during the final pass of foil rolling. However, if the content exceeds 0.1%, corrosion resistance decreases. The reason why the Si content is limited to 0.5% or less is that Si has a high solid solubility in Al, and it is better to have as little Si as possible in order to promote the rolling effect. That is, if the Si content can be suppressed to 0.01% or less, it becomes possible to produce a foil material with a small number of pinholes and excellent rollability. However, since Si is unavoidably included in Al metal, Al-Fe
-Solid solution Si as a 3i-based compound! ! 0.5% if the amount that can reduce t is suppressed to 0.5% or less
When the amount exceeds 1, the amount of solid solution Si increases, which not only increases the number of pinholes but also deteriorates the rolling properties.

As mentioned above, since Fe5Si is unavoidably included in Al metal,
By limiting the composition to the above range, it is intended to prevent the formation of pinholes in terms of metallographic structure. Other additive elements include, for example, 0.003 to 0.1% Ti and 0.5% or less C to prevent pinholes in the metallographic structure.
Addition of elements such as u, Mn, Mg, etc. does not affect the present invention.

After homogenizing the ingot with the above composition, hot rolling is performed.
There are no particular conditions, and it may be carried out as usual. Alkali cleaning is performed after hot rolling, and the alkali cleaning is performed before the cold rolling ratio after hot rolling exceeds 96%. Here, the cold rolling rate is expressed as follows.

Annealing may be performed during cold rolling.

When the cold rolling ratio is 96% or higher, the iron powder that adheres to the surface during hot rolling is buried too deeply during rolling and cannot be completely removed under the alkaline cleaning conditions of the present invention, resulting in pinholes. cannot be adequately prevented.

The conditions for alkaline cleaning in the present invention are an alkaline solution having a pH of 10 to 100 seconds. If the concentration of the alkaline solution is less than pH 0 or the cleaning time is less than 1 second, the cleaning will be insufficient and will not be sufficient to prevent the generation of pinholes. Also,
A cleaning time of more than 100 seconds is not only undesirable from the viewpoint of productivity, but also the iron powder is sufficiently removed, but at the same time the A1
is dissolved, and Al-Fe-based and Al-Fe-8i-based crystallized substances remain on the surface, which causes the same effect as the iron content and increases the number of pinholes.

It is sufficient that the temperature for performing the alkali cleaning is in the range of 15 to 90°C, and the alkali used is NaOH.

KOI(, C1(0812), etc. may be used, and it is particularly preferable to wash with 0.3 to 10% NaOH for 1 to 60 seconds.

Furthermore, in the present invention, it is desirable to perform acid cleaning consecutively after alkaline cleaning. Acid cleaning has the effect of neutralizing the alkali with acid, which prevents the alkaline solution from remaining on the board surface and deteriorating the surface quality, and dissolves the crystallized phase that has formed on the surface due to the alkali cleaning. Shows the effect of preventing the formation of pinholes.

The present invention will be described below with reference to Examples.

〔Example〕

An aluminum alloy ingot having the composition shown in Table 1 was hot rolled under normal conditions to a thickness of 3M and 6.5mm, and then
Under the conditions shown in the table, alkaline cleaning was performed with N5OH solution during cold rolling, and cold rolling was continued until the plate thickness was 0.25 mm.
And so. Note that intermediate annealing was performed at 360° C. for 2 hours with a plate thickness of 0.4 mm. The foil material thus obtained was rolled to a thickness of 7 μm (the final rolling pass was overlapping rolling), and the number of pinholes per unit area of the obtained foil was examined. The results are also listed in Table 2 in comparison with foils that have not been washed in the past.

As is clear from Table 2, the method of the present invention Nα1,2°6.7
The conventional method Nα9 without alkaline cleaning
．． It can be seen that the number of pinholes is significantly reduced compared to No. 10. On the other hand, it can be seen that the number of pinholes increases in the comparative method in which the cleaning conditions are outside the range of the method of the present invention even though alkaline cleaning is performed. That is, Na
Comparative method Nα3, in which the cleaning time with the 01l solution exceeds the range of the method of the present invention, Comparative method N, in which the concentration of NaOH solution does not reach the range of the method of the present invention (14, Comparative method, in which the cleaning time does not reach the range of the method of the present invention) It can be seen that both Nα5 and the comparative method Nα8, in which the cold working rate during cleaning exceeds the range of the present invention method, have an increased number of pinholes.

〔Effect of the invention〕

As described above, the present invention has the remarkable effect of being able to obtain an aluminum foil base with extremely few pinholes.

Claims (1)

[Claims] When hot rolling an Al alloy ingot containing 0.1 to 1.0 wt% of Fe and 0.5 wt% or less of Si, and then cold rolling, an alkali with a pH of 10 or higher is applied before the cold rolling rate exceeds 96%. A method for producing an aluminum foil substrate, which comprises performing alkaline cleaning with a solution for 1 to 100 seconds.