Background of the Invention
1. Field of the Invention
This invention relates to a new and improved plastic snap-on type tamper-evident cap and to the neck construction for a container for motor oil or the like closed by such cap.
2. Description of Related Art
Heretofore, motor oil containerrs have been closed by high density polyethylene screw caps by reason of the fact that the product tends to leak through conventional closures. The present invention uses a snap-on cap. Although snap-on caps have been used for such purpose, the structure of such caps is considerably different.
Tamper-evident caps wherein the skirt of the cap is weakened by score lines so that the lower portion of the skirt may be torn away before the cap is removed are well known in the art. Such caps are formed with internal beads which lock under shoulders on the exterior of the container neck. When the lower portion of the skirt is torn away, the remaining (reclosure) portion of the cap may be removed, but when the skirt is intact, the cap cannot be removed without evidence of tampering with the contents appearing.
Interrupted internal cap beads are also known in the art, such beads permitting flexure of the cap skirt so that the container neck is not crushed nor is the cap split.
One conventional means for removing the lower portion of the cap skirt has been formation of a line of minimum or reduced thickness in the wall of the skirt which extends horizontally around the skirt and a depending scoreline extending to the bottom of the skirt, the tear tab being located near the lower end of the depending score line. By pulling the tear tab the skirt tears along the downward-extending tear line and then circumferentially around the horizontal line of reduced thickness. The configuration of the line of minimum thickness comprises a novel feature of the present invention.
To facilitate gripping the tear tab, the lower end of the skirt has been offset in the region thereof so that the tear tab may conveniently be gripped by the thumb or finger of the user.
Summary of the Invention
The present invention is used with containers for motor oil and other liquids which tend to leak through ordinary closures. Since the interior surfaces of such necks are irregular, and further since the upper edge or lip of the neck is frequently irregular, the present invention uses exterior surfaces of the neck as sealing surfaces. Accordingly, in accordance with the present invention, the neck has three or more downwardly-outwardly slanted smooth external sealing surfaces. Preferably such surfaces are of gradually increasing diameter proceeding downwardly.
A feature of the invention is that the exterior of the neck, particularly the uppermost surfaces thereof, are machined to remove flash and to make the surfaces more nearly round. Thus the cap may more effectively seal against such surfaces.
The interior of the cap is formed complementary to the neck particularly to the upper slanted smooth external sealing surfaces. The interior of the cap may also be formed with anti-capillary ribs which engage the sealing surfaces of the neck.
The neck of the container has shoulders formed below the slanted sealing surfaces and the cap has internal beads which lock under such shoulders. In accordance with the present invention there are at least three beads formed on the interior of the cap. Two of these beads are formed on the upper portion of the cap, which is as a reclosure cap. The use of two retaining beads and three ribs insures that leakage from the container after the lower portion of the skirt (which contains the third locking bead) has been torn away does not occur.
In accordance with this invention, one of the external locking bead of the neck may be interrupted, preferably the lowest such bead. The lowermost internal cap bead may also be interrupted.
Another feature of the invention is the provision of an offset between the interior of the lower portion of the skirt and the exterior of the neck in the region adjacent the tear tab used to tear off the lower portion of the skirt. This offset facilitates the thumb or finger of the user gripping the tear tab.
Standoffs are formed in the interior of the cap at the offset portion to insure the offset remains in proper position. The standoffs also deter efforts to defeat the tamper-evident feature by blocking insertion of a prying instrument under the skirt in the region of the offset.
The provision of the offset above the horizontal line of reduced thickness leaves a lift tab after the lower portion of the skirt has been torn off. The user may pry the lift tab upward to snap the reclosure cap off the neck.
A feature of the invention is that the line of minimum thickness slants upward-outward. Thus the torn lower edge of the reclosure cap appears less frayed and thus aesthetically improved.
Still another feature of the invention is the fact that the exterior and the interior of the caps are dimensioned so that during transportation and storage the caps do not nest and hence feeding of caps through a capping machine is not inhibited.
Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.
In the Drawings
FIG. 1 is a side elevational view of the open portion of the neck of the container and the cap assembled thereon.
FIG. 2 is an enlarged view taken substantially along the line 2--2 of FIG. 1 showing on one-half of the view the exterior of the container neck and on the other half of the view a section through the neck.
FIG. 3 is a sectional view through two caps showing how they resist tight nesting.
FIG. 4 is a view similar to FIG. 1 with the lower portion of the skirt torn away.
FIG. 5 is an enlarged side elevational view of the cap.
FIG. 6 is a sectional view taken substantially along line 6--6 of FIG. 2.
Description of Preferred Embodiments
Neck 11 of the container with which the present invention is used has a top edge or lip 12. The container is of a blow-molded plastic construction and it is typical of such constructions that the top edge 12, as well as the interior, are irregular in dimension and sometimes rough. Accordingly, the present container neck 11 employs external sealing surfaces. Thus after the container has been molded it is preferably machined so that flash is removed from surface 12 and also the top external surface 13. Further, these surfaces are made more nearly round as a result of such machining. This machining is readily done in large-scale production. The round, smooth surfaces are readily sealed by ribs on the inside of the cap, as hereinafter appears.
Directing attention now to FIG. 2, proceeding downward from top edge 12, there is a first, or top, slanted surface 13 disposed at an angle of approximately 80.degree. to the horizontal which terminates in a first horizontal outer shoulder 14. Below shoulder 14 is a second slanted surface 16 which is disposed at an angle of approximately 65.degree. to the horizontal which terminates in first horizontal inward-extending shoulder 17. The angle where surfaces 16 and 17 join comprises first or top external bead 18.
Below shoulder 17 is first vertical surface 19 which terminates in a second horizontal outer shoulder 21. Third slanted surface 22 (disposed at an angle of approximately 65.degree. to the horizontal) extends downward from surface 21 and terminates in second horizontal inward-directed shoulder 23. Thus, surfaces 22 and 23 define the second external bead 24. Below shoulder 23 is second vertical surface 26 which terminates in a fourth downward-outward slanted surface 27 disposed at an angle of approximately 55.degree. to the horizontal. In normal usage, the surface 27 does not comprise a sealing surface. Below surface 27 is third horizontal inward-directed shoulder 28. The surfaces 27 and 28 define the third external locking bead 29.
Below surface 28 is third vertical surface 31 which terminates in an outward-downward slanted surface 32 disposed at an angle of approximately 45.degree. to the horizontal. At the outer edge of surface 32 is a short vertical surface 33 which terminates in an outward directed horizontal shoulder or ledge 34. Below surface 34 is the remainder 36 of the neck 11, the details of which form no part of the present invention.
It will be noted that the interior of the neck 11 generally conforms to the exterior so that the wall thickness is approximately uniform throughout.
Directing attention now to cap 41, top disk 42 on its underside has a diameter slightly greater than the diameter of lip 12. Describing now the interior of cap 41, depending from disk 42 is first slanted surface 43, which terminates in an outward directed horizontal shoulder 44. Surface 43 is parallel to and may seal against surface 13. However, as shown, an internal first rib 46 is directed to bear against and seal with surface 13. Joining the outer edge of horizontal surface 44 is second downward-outward slanted internal surface 47 which seals against surface 16 and which terminates in an internal locking bead 48, which locks under the top bead 18. Approximately midway along the surface 47 is second internal rib 49 which seals against slanted surface 16.
Below bead 48 is third downward-outward slanted surface 51 which seals against surface 22 and which terminates in second internal locking bead 52 which locks under the second shoulder 21. Third internal rib 53 seals against third slanted surface 22. Below bead 52 is outward-directed horizontal surface 54. On the exterior of the cap, slightly above the elevation of surface 54 is an external shoulder formed so that the line of minimum thickness 57 slants downward-inward. When lower skirt portion 56 is torn away (as hereinafter explained) the lower edge of the reclosure cap (FIG. 4) the lower edge thereof is aesthetically improved because it slants downward-inward.
Third internal locking bead 58 is positioned to engage under bead 29. As best shown in FIGS. 2 and 4, bead 29 of neck 11 is interrupted and is formed in two sections 59. Bead 58 is also interrupted and formed in sections 60. The alignment of sections 59 and 60 may be random. If the container is non-circular and tab 67 is oriented by the capping machine chute, sections 59 and 60 may be controlled to overlap. This permits the cap 41 to snap onto the neck 11 without likelihood of crushing the neck or splitting the cap.
The bottom edge 61 of lower skirt 56 is positioned to rest on the ledge 34 when the cap is seated on the neck.
Depending from line of minimum thickness 57 is a slanted tear line 66 formed on the exterior of lower skirt 56 which extends down to the lower edge 61. Adjacent the terminus of line 66 is a depending tear tab 67. The corner 68, where one edge of the tab 67 joins the edge 61 adjacent the slanted tear line 66, is square, whereas on the opposite edge of the tab 67, there is a rounded corner 69. This structure reduces the possibility that tab 67 may be torn off without the lower portion of the cap skirt being removed. Formed on the interior of the tear tab 67 are gripping ribs 71.
An optional feature of the invention is the formation of an offset portion 73 of the lower skirt 56 between the slanted score line 66 and a substantially vertical line 74. Standoffs 62 formed on the interior of lower skirt 56 between lines 66 and 74 cause the offset 73 to be spaced outward of the neck 11, thereby facilitating the finger or thumb of the user gripping the tear tab and the ribs 71. Standoffs 62 also prevent a prying instrument under the offset 73. Accordingly the user pulls the tab 67 upward, causing the skirt to tear along the score line 66 upward from corner 68 to line 57. Continued pulling on the tab 67 causes the cap 41 to tear along line 57. Thereby the lower skirt portion 56 and the locking bead 58 are torn away. As shown in FIG. 7, the line of minimum thickness slants downward-inward. Thus the bottom edge of the reclosure cap above line 57 appears smooth, rather than frayed.
The portion of the cap above line 57 constitutes a reclosure cap (see FIG. 5) held in place by the beads 48 and 52 locking under the beads 15 and 24, respectively. When the lower portion 56 of the skirt is intact, the additional bead 58 prevents the cap from being removed from the container neck. If attempts are made to remove the cap in order to tamper with the contents of the container, the skirt tears along the line 57, providing evidence of tampering.
Lift tab 75 is part of offset 73 above line 57. Tab 75 may be used to pry off the reclosure cap (see FIG. 4) after the lower portion of the skirt has been torn off.
The exterior of the cap 41 generally follows the interior thereof so that it is of substantially uniform thickness. However, to facilitate gripping the cap, external vertical ribs 76 may be formed exteriorly of the surfaces 47 and 51.
During transportation and storage of the caps, as best shown in FIG. 3, it is desirable that the caps not nest tightly. The upper ends of the ribs 76 fit against the lower surface of bead 58. Thus the lower cap cannot fully nest in the upper.
In the claims, terminology somewhat inconsistent with the terms used in the foregoing specification have been employed:
Top external surface 13 is referred to as upward-inward slanted external surface,
second slanted surface 16 as first, external (downward-outward) slanted surface,
first inward-extend shoulder 17 as first horizontal inward-directed shoulder,
third slanted surface 22 as second external downward-outward slanted surface,
fourth downward-outward slanted surface 27 as third external slanted surface,
first slanted surface 43 as upward-inward slanted internal surface,
internal first rib 46 as upward-inward slanted internal surface,
second downward-outward slanted internal surface 47 as first internal downward-outward slanted surface,
internal locking bead 48 as first internal bead means,
second internal rib 49 as circumferential internal rib
third downward-outward slanted surface 51 as second internal downward-outward slanted surface,
second internal locking bead 52 as second internal bead means, and
third internal locking bead 58 as third bead means.