Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
2001-04-23
2004-02-17
Tsang-Foster, Susy (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C428S681000, C148S529000
Reexamination Certificate
active
06692869
ABSTRACT:
INDUSTRIAL FIELD
The present invention relates to a surface treated steel sheet for a battery container, a method of producing a surface treated steel sheet for a battery container, a battery container and a battery using the steel sheet.
BACKGROUND OF THE INVENTION
With the increase of the demand for alkaline manganese batteries used for small-sized domestic electric devices such as shavers, the demand for the improved performance of these batteries has been increased. Above all, the conductivity of electrons between the inner surface of a battery container which is the positive electrode and the positive electrode active material inserted into a battery should be made excellent so as to achieve the improved battery performance. For that purpose, a lot of proposals are disclosed as follows:
A method of applying a coating having excellent conduction on the inner surface of a container (Laid Open Japanese Patent Sho. 58-48361 and Laid Open Japanese Patent Sho. 59-160959),
a pre coated steel sheet in which adhesion of the coating is improved (Laid Open Japanese Patent Hei. 6-342653 and Laid Open Japanese Patent Hei. 8-287885),
as the other methods for improving adhesion of the coating,
a method of forming concave and convex portions on the inner surface of a container (Laid Open Japanese Patent Sho. 59-209056), and
a method of causing roughened surface or cracks on the inner surface of a container (Laid Open Japanese Patent Hei. 9-306439).
However, the conventional method of pre coated steel sheet or the like, in which a coating having excellent conduction (conductive coating) is applied on the one side of a steel sheet to become the inner surface of a container, is not favorable because the conductive coating is easily peeled off when the pre coated steel sheet is formed into a battery container, while a method of applying a coating on the inner surface of a container causes the increase of the process which produces an increase in cost.
Considering these problems, the objective of the present invention is to produce an improved surface treated steel sheet having more excellent conductance with the positive electrode active material.
Further, another objective the present invention is to produce a battery container and a battery using the surface treated steel sheet.
DISCLOSURE OF THE INVENTION
The surface treated steel sheet for a battery container is characterized in that a graphite dispersed nickel plating layer is formed on at least one surface of the surface treated steel sheet, that is to become the inner side of a battery container.
The surface treated steel sheet for a battery container is characterized in that a graphite dispersed nickel alloy plating layer is formed on at least one surface of the surface treated steel sheet, that is to become the inner side of a battery container.
In these surface treated steel sheets it is preferable that the alloy plating layer be any layer of nickel-cobalt alloy, nickel-cobalt-iron alloy, nickel-manganese alloy, nickel-phosphorus alloy or nickel-bismuth alloy.
In these surface treated steel sheets it is preferable that a diffusion layer be formed under the plating layer.
Further, in these surface treated steel sheets it is preferable that any layer of mat nickel plating, semi-gloss nickel plating, gloss nickel plating, nickel-cobalt alloy, nickel-cobalt-iron alloy, nickel-manganese alloy, nickel-phosphorus alloy or nickel-bismuth alloy be formed under the plating layer.
In these surface treated steel sheet it is preferable that the content of graphite in the plating layer is 0.1 to 25 weight %.
The method according to the present invention is characterized in that a plating layer is formed on at least on one side to become the inner side of a battery container using a plating bath including nickel salt, surface active agent and graphite powder.
The method according to another embodiment of the present invention is characterized in that a plating layer is formed on at least one side to become the inner side of a battery container using a plating bath including one kind or more of metal salt consisting of cobalt salts, iron salts, manganese salts, salts of phosphorus anions and bismuth salts, nickel salts, along with a surface active agent and graphite powder.
The battery container according to another embodiment of the present invention is characterized in that it is produced from the above-mentioned surface treated steel sheet.
The battery according to the present invention is characterized in that it uses the battery container produced from any surface treated steel sheet produced as described in the present specification.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described in detail below.
[Steel Sheet Used]
A cold-rolled steel sheet based on a plain steel, particularly based on a continuously casted low carbon aluminum killed steel is used as a steel sheet for the present invention. In addition, a hyper low carbon steel having 0.003 wt % or less of carbon content, an anti aging steel that is the hyper low carbon steel including metals such as niobium, titanium and so on, or a stainless steel sheet including 3 to 18 wt % of chromium content is also available.
[Substratum Nickel Plating]
In the surface treated steel sheet for a battery container, it is preferable that a layer of nickel plating be formed on a steel sheet. Hereinafter, the nickel plating is described as substratum nickel plating. The objective of the formation of the substratum nickel plating layer is to produce enough corrosion resistance even after the plated steel sheet is formed into a battery container to prevent corrosion of the steel sheet.
As a plating bath for the substratum nickel plating, the bath used in the usual nickel plating such as watts bath, sulfamate bath, borofluoride bath or chloride bath can be applied to the present invention. There are 2 types of nickel plating, electrolytical plating and electroless plating. While electroless plating is available, in general electrolytical plating is easier since the bath composition and the plating thickness can be controlled. The current density of 3 to 80 A/dm
2
is applied in electrolytical plating and it is preferable to stir the bath by air bubbling for forming a plating layer having a uniform thickness. Furthermore, pH of the bath is preferably in the range of 3.5 to 5.5, and the bath temperature is preferably in the range of 40 to 60° C.
In the present invention, as a substratum nickel plating, any type of mat plating without the use of organic additives, semi-gloss plating or gloss plating using organic additives can be applied. The quantity of the substratum nickel plating layer is preferably 0.5 to 5 &mgr;m. The quantity of less than 0.5 &mgr;m produces insufficient covering of the steel sheet, which can not cause enough corrosion resistance that is the objective of the substratum nickel plating, while a layer of more than 5 &mgr;m saturates the covering effect as well as causing unfavorable economical effect. It is preferable to form the substratum nickel plating on both surfaces of a steel sheet in view of securing corrosion resistance. It is preferable to form the plating having a thickness of about 1 to 3 &mgr;m on the one surface to become the inner surface of a container, while it is preferable to form the plating having a thickness of about 1 to 4 &mgr;m on the other surface to become the outer surface of a container. It is preferable that the plating thickness on the surface to become the outer surface of a container is a little greater than that on the surface to become the inner surface of a container in view of preventing rust occurrence of a battery container.
Further, as the other substratum plating, for example nickel-cobalt plating, nickel-cobalt-iron plating, nickel-manganese plating, nickel-phosphorus plating or nickel-bismuth plating based on alloy plating bath comprising nickel and any of cobalt, manganese, iron, phosphorus or bismuth can also be available. As a plating bath, known sulfate bath, sulfamate bath or the like can be
Ohmura Hideo
Ohmura Hitoshi
Tomomori Tatsuo
Yamane Keiji
Browdy and Neimark , P.L.L.C.
Toyo Kohan Co. Ltd.
Tsang-Foster Susy
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