Bottles and jars – Neck – Structure to receive a particular closure
Patent
1997-07-29
1999-12-21
Cronin, Stephen K.
Bottles and jars
Neck
Structure to receive a particular closure
215 45, 215344, 264536, 425527, B65D 4148, B29C 4950, B29C 2500
Patent
active
060036990
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a new and improved blow molded neck construction for bottle or other container, a cap therefor, a method of forming said neck and molds for forming said neck. More particularly, it relates to the neck finish for a blow molded plastic bottle characterized by the fact that when used with a cap having a plug (i.e., inner skirt) the surface of the neck against which the plug seals is a seal surface without parting lines and no portion has a diameter less than tat of the seal surface. Hence, the plug seals against a smooth surface and leakage is prevented.
2. Description of Related Art
An exemplar of the prior art is U.S. Pat. No. 4,691,834 which shows an upward inward directed flexible flange sealing against the corner of the intersection of the outer wall of the plug and the underside of the top of the cap. The neck sealing surface is, inherently, somewhat uneven and ragged since the neck is cut or sheared adjacent this sealing surface. In the present invention, however, the neck is trimmed on the edge above the seal surfaces but such edge is not the portion of the neck which seals against the cap plug.
The references cited against said U.S. Pat. No. 4,691,834 are likewise distinguishable.
U.S. Pat. Nos. 4,625,876 and 4,798,301 show curved plug contacting surfaces but these are of substantially the same diameters as the inner edge of the flanges which engage the underside of the top of the cap.
SUMMARY OF THE INVENTION
The bottle of the present invention is blow molded in a split mold by techniques well known in the art. The surfaces of the mold which define the neck structure cause the neck shape hereinafter described. An upper portion of the parison above the neck is trimmed or cut from the neck according to conventional practice (e.g. pull-up trim, spin trim, ram-down, etc.) In one neck structure the circle at which the upper portion of the parison is severed from the neck is the inner edge of an inward upward slanted flange. The other end of the flange merges into a curved surface which extends inward a greater distance than the aforesaid edge to merge with an internal sealing surface of lesser diameter than said edge. The neck structure above the neck sealing surface may have rapidly changing diameters which form a flexible membrane due to parison stretching in the blow molding process. In one form of the invention, below the sealing surface the exterior of the neck structure slants downward outward to a horizontal shoulder and then extends downwardly and then outwardly to a second or lower shoulder. Other cap engaging means may be used.
A cap with which the neck is used has a top having a depending central plug or inner skirt, the outer surface of which seals tightly against the sealing surface of the neck. The cap also has an outer skirt having internal sealing beads which engage the upper and lower shoulders of the neck to hold the cap in place. The lower portion of the outer cap skirt may be removed by the user engaging and pulling a pull tab which causes the lower part of the skirt to disengage at a circumferential score line. Until such lower skirt is removed, the cap and neck are tamper-evident. Other types of neck engaging means may be emphasized.
Several different ways may be employed to form the neck finishes of the present invention in blow molding operations. One such means employs a conventional blow mold wherein a blow dome is formed above the neck finish with several abrupt bends in the parison between the blow dome and the neck sealing surface. The blow dome is trimmed from the neck in a conventional trimming operation.
In another modification of the invention, the shear steel located above the neck finish insert has a projecting extension which is engaged by an outward projection on the blow pin so that when the blow pin is withdrawn, the two extensions shear the parison above the sealing surface of the neck.
In still another form of the invention, the shear steels have inward projections, and the blow pi
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Laszlo Sandor G
Luch Daniel
Repp Richard E
Caplan Julian
Cronin Stephen K.
Newhouse Nathan
Portola Packaging, Inc.
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