Tab for easy-open can end

A tab for an easy-open can. The tab carries an anodic insert of zinc, zinc-plated steel or equivalent to prevent corrosion. The insert underlies the tab where white rust which forms on zinc is hidden from view.

This invention relates to an improved tab for an easy-open can. 
The tab is particularly useful for cans in which the segment cut from the 
can end remains attached when the can is opened, thus forestalling 
littering. Usually the ends of such cans are aluminum, and they have a 
score line which defines a segment to be punched inwardly of the can. A 
tab is riveted to the can end adjacent the score line and may be lifted to 
apply leverage to the material within the score line, and thus punch it 
inwardly. 
There is a problem in constructing a tab which has sufficient mechanical 
strength and yet does not corrode. A special aluminum alloy has been used, 
but is in short supply. Tinplate has not been satisfactory because a 
tinplate tab rusts around its exposed untinned edges. Zinc-coated steel 
has been used, but shows unsightly white rust unless lacquered. 
An object of our invention is to provide an improved tab which can be 
formed either of tinplate or blackplate, but does not rust or otherwise 
become corroded. 
A more specific object is to provide an improved tab of tinplate or 
blackplate which carries a hidden anodic insert of zinc or zinc-plated 
steel or equivalent to prevent corrosion of either the tab or the can end.

FIGS. 1 and 2 show a portion of an easy-open can which includes an end 10 
and a cylindrical side wall 12. The end and side wall may be aluminum, 
tinplate or blackplate and may be lacquered or not. The end has a 
depressed area 13 and a score line 14 within the depressed area. A tab 15 
is affixed to the end, preferably with an integral rivet 16, also within 
the depressed area. The tab itself has an arcuate cut 17 extending part 
way around the rivet, and a point 18 overlying the area of the end within 
the score line 14. The tab may be lifted to open the can. The tab comes 
apart at its cut 17 and bends along a line 19. The point 18 bears 
downwardly against the area within the score line 14 and thus punches this 
portion of the end inwardly, as shown in FIG. 2. The punched portion 
remains attached through a neck 20. Can ends of this construction are 
known and not claimed to be of our invention. 
In accordance with our invention, we apply a small anodic insert 21 to the 
underside of the tab 15, as shown in FIGS. 3, 4 and 5. The insert may be 
of zinc, zinc-plated steel or other anodic material. The insert lies 
within the area defined by the cut 17 and bend line 18. The insert has a 
hole 22 to receive the rivet 16. The insert underlies the portion of the 
tab which remains against the can end when the tab is lifted. Hence 
unsightly white rust (zinc oxide) which forms on zinc is hidden from view. 
If the tab is tinplate, the insert effectively provides anodic protection 
to the exposed untinned edges and at the score line. The insert can serve 
also to protect a blackplate tab or a can end of tinplate or blackplate. 
Otherwise a tinplate end is subject to corrosion at the score line.