Stock material or miscellaneous articles – Structurally defined web or sheet – Continuous and nonuniform or irregular surface on layer or...
Reexamination Certificate
1999-04-29
2002-11-05
Resan, Stevan A. (Department: 1773)
Stock material or miscellaneous articles
Structurally defined web or sheet
Continuous and nonuniform or irregular surface on layer or...
C428S332000, C428S458000
Reexamination Certificate
active
06475597
ABSTRACT:
TECHNOLOGICAL FIELD
The present invention relates to a thermoplastic resin coated aluminum alloy sheet, suitable for use in severe forming conditions, manufacturing method thereof, and manufacturing device thereof. More specifically, it relates to thermoplastic resin coated aluminum alloy sheet for use in can which can withstand severe forming conditions, intended to be formed into not only a can lid or a drawn can, but also for a drawn and ironed can, a drawn and stretch-formed can, a drawn, stretched and ironed can and such, manufacturing method thereof and manufacturing device thereof.
BACKGROUND TECHNOLOGY
Aluminum alloy sheet which is laminated with thermoplastic resin, for instance, polyester resin, is already being used for can lid and such. However, if the adhesion of the laminated thermoplastic resin layer to the aluminum alloy sheet is insufficient, the thermoplastic resin layer might peel off during the forming, or corrosion might progress from the part where adhesion is insufficient. This adhesion after forming is greatly influenced by the surface condition of the aluminum alloy sheet in addition to the formability of the aluminum alloy sheet and the characteristics of the laminated thermoplastic resin layer. Thus, in order to improve the adhesion of the thermoplastic resin layer or the coating film to the aluminum alloy sheet, the following surface treatments are conventionally given to the aluminum alloy sheet.
(1) Method of giving chemical treatment such as phosphorus acid treatment or chromic acid treatment to the aluminum alloy sheet.
(2) Method of coating thermosetting resin primer on one side of the thermoplastic resin film or aluminum alloy sheet.
(3) Method of forming an anodic oxide film with minute pores, having diameter of 200 angstrom or more and pore depth of 5 &mgr;m or less, on the surface of the aluminum alloy sheet, using a solution containing chromic acid (Japanese laid open publication Hei 3-44496).
(4) Method of forming an oxide film of 20 angstrom or more on the aluminum alloy sheet by heating said sheet in atmosphere for two hours or more in temperature range of 250-650° C. after said aluminum alloy sheet is cleaned. (Japanese laid open publication Hei 6-272015).
(5) Method wherein after the aluminum alloy sheet is cleaned, it is electrolytically treated using oscillating current in an alkali solution and an oxide film, having a thickness of 500 to 5000 angstrom and ramified micro pores is formed on the aluminum alloy sheet (Japanese laid open publication Hei 6-267638).
In the method of the chemical treatment such as phosphorus acid treatment or the chromic acid treatment of method (1) phosphate, chromate, or fluorine compound, and such, are mainly used for the treating solution. The thus formed chemical treatment film is effective in the improvement of adhesion and generally used. However, enormous facility for waste water treatment is needed for draining of the treating solution in order to prevent environmental pollution. Therefore, such chemical treatments are undesirable from the viewpoint of environmental protection. The method of coating a primer for adhesion of method (2) increases the cost by coating the primer and requires a surplus process for baking the coating as well, and is not desirable from the viewpoint of productivity. Furthermore, it needs an exhaust processing equipment to dispose of the organic solvent. As for the method of forming the anodic oxide film having pores of a specific diameter and depth by the use of chromic acid solution of method (3), it is not desirable from the viewpoint of productivity since the anodic oxide film requires a long time to be formed. Also the thermoplastic resin layers might peel off when subjected to severe forming processing. Moreover, it requires a facility for waste water treatment for environmental pollution prevention. As for method (4), in which the aluminum alloy sheet is heated for a long time in the atmosphere to form an oxide film thereon, the thermoplastic resin layer peels off when subjected to severe forming, like Method (3). It further requires along time to form the oxide film and is not desirable from the viewpoint of productivity. The method (5), in which an oxide film of 500 to 5000 angstrom is formed by electrolytical treatment using oscillating current in an alkali solution, enables continuous surface treatment in a short period of time by electrolysis and is effective in the adhesion of the laminated resin film. However, after the resin film is laminated, said laminated resin film peels off when subjected to such severe forming as drawing, followed by stretch-forming and further ironing. Therefore, adhesion after forming is far from sufficient and cannot endure severe forming.
DISCLOSURE OF THE INVENTION
The technical object which the present invention aims to achieve is to provide a thermoplastic resin coated aluminum alloy sheet, of which the thermoplastic resin layer has excellent adhesion after forming and does not peel off even in further severe forming, compared to the above-mentioned, conventionally surface-treated aluminum alloy sheet, the manufacturing method and the manufacturing device thereof. Concretely, it is to provide a thermoplastic resin coated aluminum alloy sheet having excellent adhesion after forming, in which the thermoplastic resin layer does not peel off ever when subjected to deep drawing followed by stretch-forming and further followed by ironing and to provide a manufacturing method thereof and manufacturing device thereof which are cost-effective, environment-friendly and enable rapid production.
The thermoplastic resin coated aluminum alloy sheet of the present invention is characterized in that at least one side of an aluminum alloy sheet having comparative surface area increase rate of 3-30% is covered with thermoplastic resin.
Said aluminum alloy sheet has minute pores formed on the surface. The minute pores have preferably an average diameter of 50 to 3000 nm, maximum depth of 1000 nm or less, and the duty area rate of 10 to 90%. Moreover, it is more preferable that the average diameter is 200 to 900 nm and the depth is shallower than half of the diameter and that the pores are formed in the thickness direction of the aluminum alloy surface.
Moreover, it is preferable that the thermoplastic resin is polyethylene terephthalate, copolyester resin mainly composed of ethylene terephthalate unit, polyester resin mainly composed of butylene terephthalate unit and compound resin of polyester resins blended and/or multi-layered.
In addition, it is preferable that the polyester resin layer to be laminated is a multi-layered resin comprising an upper layer and a lower layer of polyester resin, and an intermediate layer of blended resin in which bis-phenol A carbonate is blended to polyester resin or bisphenol A polycarbonate.
The method of manufacturing the thermoplastic resin coated aluminum alloy sheet of the present invention is characterized in that an aluminum alloy strip is continuously treated in an alkaline aqueous solution, rinsed with water, treated in acid aqueous solution, rinsed with water, dried, and after that covered with thermoplastic resin.
It is preferable that the alkali aqueous solution is an aqueous solution having as the main component of one or more than one compound selected from the group of hydroxide, hydroxide, carbonate, bicarbonate, silicate, and borate of alkali metal or ammonium in quantity of 10 to 200 gm/l.
Moreover, the above-mentioned acid solution preferably has as the main component 10 to 300 g/l of one or more than two types selected from sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid.
In addition, it is preferable that the treatment with alkali aqueous solution is spraying treatment or the dipping treatment in the alkali aqueous solution, and that the treatment with the acid aqueous solution is spraying treatment or dipping treatment in the acid aqueous solution.
The manufacturing device of the thermoplastic resin coated aluminum alloy sheet of the present invention is characterized in
Komai Masao
Shimizu Keiichi
Tanabe Jun-ichi
Taniguchi Ayumu
Bernatz Kevin M
Browdy and Neimark , P.L.L.C.
Resan Stevan A.
Toyo Kohan Co. Ltd.
LandOfFree
Thermoplastic resin-coated aluminum alloy plate and method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermoplastic resin-coated aluminum alloy plate and method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastic resin-coated aluminum alloy plate and method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2987653