CA1119113A

CA1119113A - Ring strength

Info

Publication number: CA1119113A
Application number: CA000350407A
Authority: CA
Inventors: Jerry D. Hawkins
Original assignee: Continental Group Inc
Current assignee: Continental Group Inc
Priority date: 1979-05-18
Filing date: 1980-04-23
Publication date: 1982-03-02
Also published as: US4227624A; FI801592A; NO801419L; DK215380A; AU5793980A; EP0019424A1

Abstract

ABSTRACT OF THE DISCLOSURE
A tape made of a laminate of thermoplastic plastic material and metal having a finger ring portion in which the edge of the hole is hemmed by folding the plastic portion upon itself and heat sealed to each other.

Description

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IMPROVED RING STRENGTH

, DISCLOSURE OF THE INVENTION
This in~ention is directed to tape seals for pour openings of containers of the type sho~Yn and discussed in U.S. Pa*ent 3,990,615 and 4,116,35g. In such structures, a tape strip made of a la~inate of a thermoplastic ana derad soft ~luminum is used. The aluminum is of minimum tensile strength rand the laminate is very thin. The tape comprises a rectangu-~ar body porti~n which is attached r_t on~ end to the end panel o~
a can by a permanent bond and in the area of the pour opening is attached by a peelable bond. A finger rin~ is p~ovided at the free end of the tape and in prior practice the ring hole has been hemmed by folding an edge portion of the tape about finger hole with the hem metal portion or the tape o~re-rlaid directly over the metal portion of the ring. In many instanc~s, where the peelable bond was strong or if any cracks de~reloped in thc metal in the hem about the ring hole, the user, in pull-! ing Oll tl~c t~lpe to open the container, would break the r;ng porti()n thcreby ma~ing it difficult to open the can ~ccausc of lac}; of purchasc on the bro~en ring which would, if pulled ~y tl~e ullbrokerl part, then entirely break off.

~; ' SU~I~IARY OF T~-IB INVF.NTION
This invention is directed to a novel construction -of the pull ring of a tape seal for the pour opening of a high-pressure container for pressurized beverages.
A more specific object of 1:he inven1:iol1 is to p3`0-( vide a laminated tape having a weak metal component and a plastic component bonded thereto wherein a pull ring is prQ-vided at one end and the margin of the finger opening in the ring is hemmed in such manner that a plastic to plastic over-lap is obtained and the same are bonded to each other to provide strong structural integrity so that the ring will not break apart.
These and other objects and advantages-inherent in and encompassed by the invention will become more apparent from the Specification and drawings, wherein:
Figure l is a top plan view of a can end incorporat-ing the invention;
Figure 2 is a top plan view of the sealing tape;
Figure 3 is an enlarged cross-sectional view thereo ta~en substantially on line 3-3 of Figure 2; and Figure 4 is a cross-sectional ~-iew similar to Fi~ure 3 showing the prior art.

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- ~ , DESC~IPTIO~ OF THE INVENTIO~
-The invention is embodied in ~ can end 2 which has a pour opening 3 which is covered by a tape seal strip 4j which is a laminate composed of a dead soft aluminum foil 5 and a thin layer of thermoplastic material such as poly}lropylene.
As best seen in Fig. 2, the strip is a rectangular structure having a body portion of t~:hich overlies the pour opening ll and is secured to the can top by a peelable ad-hesive of the type describea in U. S. Patent 3,9~0,615. The end 8 of the tape is secured by a permanent bonding adhesive such as disclosed in U.S. Patent 4,029,033. A ~rasp or lift end portion lO is provided on the tab which is normally folded over the body portion 7 of th~ tab. The-lift portion lO has a ring 12 which has a finger hold 13 with a hemmed edge por-tion 14.
The hemming which has been done before in theprior art as seen in Fig. 4, has folded the portion 14 in a manner bringing the metal part 15 over $he metal portion 5 thus merely doubling the structure about the hole 13. Al-though this hemming strengthened the ring, it doe~ not de-~el~ a structure that ~ill not brea~ ap~r~ as has frequently occurred in the prior art.
I have found that the structure would be greatly improved by hemming in the reYerse way, that is, by folding Zs the portion 14 under the ring and thus bringing the hem plastic into contact with the plastic laminate beneath the ring as seen in Fig. 3 and thereafter heating and pressing the same togethcr so that they are bonded together or melted together into an integral structure. Thus, when the ring is pulled, the load is transmitted directly to both the mctal as ~ell as thc ~lastic laminate. The ~lastic is approximately doublcd in thic~ness ancl integral about the finger hole thus adding to its strength. Also, since the hem cxtends out~ardly and can be compressed thin b~ squee7ing out the plastic, the rin~
is made thin and docs not interfere wit11 folding thc ring over the body for tOUCi1 welding the ring to the body as dis-closed in U. S. Patent 3~9S5,261.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A pull-tab comprising one elongated laminate member made of metal foil and thermoplastic film and having a body and a grasp section at one end of the body, said grasp section comprising a ring having ring portion with a finger hole therein, a hem about the finger hole having a flange portion bent against the ring portion with the plastic film on the flange portion and the ring portion facing each other, and a heat bond between said portions forming an integral structure.

2. The invention according to claim 1, wherein the metal foil forms the edging about the opening.

3. The invention according to claim 1 and said metal foil being dead soft aluminum.

4. The invention according to claim 1 and said thermoplastic being polypropylene.

5. The invention according to claims 2 and 3.

6. The invention according to claims 3 and 4.

7. A pull-tab of the type adapted to be adhesively adhered to a container wall over a pour opening therein comprising;
a flat laminate strip having a reverse side comprising a thermoplastic film and an obverse side comprising a tearable metal foil;
said tab having a body part and a pull ring part adapted to be folded over said body part;
said pull ring part having a finger hole therein, a hem about said hole folded over said ring part with the plastic film on the hem overlapping the plastic film on the ring part, and means permanently bonding said film on the hem with the film on the ring part, said film being squeezed out between the hem and ring part to reduce the thickness of said film therebetween in the overlap.