WO1999032364A1

WO1999032364A1 - Sift-resistant rotor cap with knockout

Info

Publication number: WO1999032364A1
Application number: PCT/US1998/027453
Authority: WO
Inventors: David C. Baxter
Original assignee: Weatherchem Corporation
Priority date: 1997-12-23
Filing date: 1998-12-23
Publication date: 1999-07-01
Also published as: AU1945799A

Abstract

A rotor-type sift-resistant dispensing closure (10) of injection-molded thermoplastic having a base (11) that provides a resilient seal (33) on its dispensing hole (28) and a rotor (12) carried on the base (11) in a position that compresses the seal (33) for sealing effectiveness. The rotor (12) is accurately maintained in a flat configuration by the base (11) which retains the rotor (12) both at its center and at its periphery (14) and which stabilizes the rotor (12) against distortion with upstanding supporting ribs (27, 29) situated between the center and periphery (14) of the rotor (12). The dispensing hole (28) in the base (12) has a knockout panel (51) that assures a sift-proof construction, simplifies assembly of the closure, and is easy to open.

Description

SIFT-RESISTANT ROTOR CAP WITH KNOCKOUT

BACKGROUND OF THE INVENTION The invention relates to injection-molded thermoplastic dispensing closures and, in particular, to improvements in sift-resistant closures of the rotor and base type.

PRIOR ART Fine powders, such as baby powder and talcum powder are notoriously difficult to package in containers with sift or sprinkle dispensing features. This problem involves the tendency of the powder to sift or escape out of the dispensing closure openings when the package is handled from the point of filling to the ultimate point of use by a consumer. Typically, this unintended sifting or escaping of product while not significant in terms of the volume of the contents of the package, is detrimental to the appearance of the product package on the retailing shelf. Good shelf presentation is especially important in the cosmetic and health care industries. Commonly, the unintended sifting occurs even though the closure is assembled in a closed position and is not operated until after it is purchased by the consumer. Talcum powder and the like has been packaged in composite containers having two-part rotor-type plastic closures. One part comprises a rotor and the other part comprises a base for the rotor fixed to an opening of the container. The rotor is turned between positions where any dispensing apertures in the base are covered by the rotor so that the closure is closed and where one or more apertures in the base is uncovered by an aperture in the rotor turned into alignment with this base aperture. It has been attempted to seal the base aperture against the overlying rotor surface with an annular ridge around the base aperture. Customarily, rotor and base closures have been offered in either of two styles of rotor and base connections. In one style, the rotor is rotatably fixed at its center by a post and in the other styles the rotor is rotatably fixed at its periphery to the base. In one closure in the prior art, it is attempted to retain the rotor on the base with a post integral with the center of the rotor that snaps into a blind hold in the base and to simultaneously retain the rotor on the base with a depending skirt on the rotor that catches in an undercut in the base below the main central web of the base. U.S. Patent 5,383,582 discloses a sift-resistant rotor-type closure that offers improved performance over earlier closures in both sift-resistance and ease of use by the consumer. As disclosed in this patent, the rotor is uniformly supported slightly above the underlying adjacent surface of the closure base by a central rib and an arcuate rib both concentric with the axis of rotation of the rotor and by a sealing lip surrounding the dispensing hole in the base and located in the area of the base where the arcuate rib is absent. The sealing lip is somewhat resilient and is proportioned to press against the underside of the rotor to afford good sealing effectiveness.

SUMMARY OF THE INVENTION The invention provides a rotor-type dispensing closure that is sift-proof prior to opening and is highly sift-resistant once opened by the consumer. As disclosed, the closure has the general arrangement of the product disclosed in U.S. Patent 5,383,582 and includes an integrally molded fully sealed breakout panel across the dispensing hole of the base. The breakout panel, in accordance with the invention, is situated within the boundary of the dispensing hole. The panel is surrounded by a thin, frangible membrane that ensures a low breakout force. The breakout panel is stabilized against inadvertent rupture by a series of bridge-like reinforcement elements spaced around its periphery. A hinge element joins the panel to the main part of the base and serves to keep the panel from breaking loose from the base when broken out of the dispensing hole. In the illustrated embodiment, the panel is relatively thin as compared to the nominal thickness of the base. This feature allows it to be successfully molded at high production speeds despite its near isolation from remaining parts of the base resulting from the very thin, frangible membrane. The panel is preferably formed within a plane of the resilient lip seal surrounding the base dispensing hole. This location enhances the ability of the panel to be broken out of its molded location with reduced effort because the flexibility of the seal allows the panel to be broken progressively along its boundary rather than requiring the user to overcome the full strength of the panel boundary at one time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a closure assembly embodying the invention; FIG. 2 is a plan view of the base of the closure assembly; FIG. 3 is an enlarged fragmentary view of an initially sealed dispensing hole area of the base taken in the plane 3-3 in FIG. 2; FIG. 4 is a plan view of a rotor of the closure assembly; FIG. 5 is a cross-sectional elevational view of the closure assembly taken along staggered planes indicated by the lines 5-5 in FIG. 1; FIG. 6 is an enlarged fragmentary bottom view of the dispensing hole area in the base; FIG. 7 is a greatly enlarged fragmentary cross- sectional view of a typical reinforcing bridge area extending radially between a sealing lip at the base dispensing hole and a breakout panel; FIG. 8 is a greatly enlarged fragmentary sectional view of a hinge bridge extending radially between the sealing lip and the breakout panel; and FIG. 9 is a bottom plan view of the base schematically illustrating the flow direction of material when the base is injection molded.

DESCRIPTION OF THE PREFERRED EMBODIMENT A closure 10 constructed in accordance with the invention includes a base 11 and a rotor 12 each preferably injection molded of a suitable thermoplastic material such as polyethylene. The illustrated closure 10 is particularly suited for use with composite containers known in the art. The base 11, which in the illustrated case is generally circular, includes a central web or wall 13 and a peripheral rim 14 integrally molded around the web. The rim 14 has the general form of a cylindrical wall. The web 13 is a generally circular planar construction that lies in a plane perpendicular to the axis of the rim 14. At its lower end, the base rim or skirt 14 is tapered so that it has a reduced outside diameter, at a minimum at its lower edge 16, to facilitate its assembly into a container. At its upper end, the rim 14 includes an outwardly directed radial flange 17 that forms a radial shoulder 18 adapted to abut the upper edge of a composite cylindrical container in a conventional manner. On its interior, the rim 14 is formed with an internal circumferential groove or recess 19 above the web 13 and bounded by a conical or radial face 21. Above this face 21, an interior surface 22 of the rim 14 is tapered slightly radially outwardly increasing in diameter with increasing distance from the web 13 preferably so that at its upper end 23 the rim 14 has an internal diameter at least as large as the major diameter of the rotor 12. At its center, the web 13 has a circular hole 26 extending therethrough. Concentric with the hole 26, is an upstanding rib 27 having a rounded or semi-circular cross-section (FIG. 5) . In the web 13 radially between the hole 26 and rim 14 is a dispensing opening 28 which in the illustrated example is circular in form. A second upstanding rib 29 concentric with the center hole 26 extends on the web 13 over an arc subtending an angle that is sufficient to allow its ends 31, 32 to lie adjacent the dispensing opening or hole 28 (FIG. 2) . In the illustrated example, this arcuate length is approximately 270°. The arcuate rib 29 has a cross-section and height above the web 13 substantially the same as the central rib 27. It will be understood that these ribs 27, 29 have their axially upper regions in a common imaginary plane that is closely dimensionally located with respect to the undercut or groove surface 21. At its upper side, the dispensing opening 28 has an integral sealing lip 33 that is relatively resilient due to a reduced thickness wall section compared to the average wall thickness of the base 11. In its free state, the sealing lip 33 extends above the ribs 27 and 29 a substantial distance. Referring to FIG. 3, the base dispensing opening 28 is initially closed by a breakout panel 51 integrally molded with the base 11. The panel 51 which is generally planar and in a plane parallel to the plane of the web or wall 13 is substantially thinner than the thickness of the web; for example, the panel can have a thickness of about .028 inches while the web can have a thickness of .040 inch. The panel 51 is joined to the sealing lip 33 continuously along its periphery by a very thin membrane 52 which can be about .003 inch thick, for example. The radial width, measured in a direction parallel to the base wall or web 13 , of the membrane 52 is similarly small depending on the geometry of the adjacent surfaces of the panel 51 and sealing lip 33. A plurality of integral reinforcing bridges 53 are spaced around the perimeter of the breakout panel 51. The bridges 53, which underlie and merge with the membrane 52, extend radially between the sealing lip 33 and the panel 51. The reinforcing bridges 53 are shown in typical cross-section in FIG. 7 taken in a plane transverse to a radial line from the center of the panel 51. The bridges 53 are relatively small, for example, having a height of approximately .009 inch and in the illustrated embodiment are 7 in number. An integral hinge 54, like the bridges 53, lies radially between the sealing lip 33 and panel 51 and merges with the lower surface of the membrane 52. The cross-section of the hinge 54, taken in the plane transverse to a radial line from the center of the panel 51, is shown in FIG. 8. By way of example, this cross-section can have dimensions of about .009 inch high by about .069 inch in length, i.e. measured in a direction parallel to the plane of the panel 51. The hinge 54 is on a side of the panel 51 remote from the gate. With reference to FIG. 9, the base 11 is injection- molded from a gate located at a point indicated at 56. The hinge 54 is on a side of the panel 51 remote from the gate 56. Flow of material from the gate 56 into the mold space forming the panel 51 is largely through the area of the hinge 54 as suggested by the diagrammatic arrows 57. This results from the obstruction to flow presented by the hole 26 and the relatively large flow area afforded by the hinge construction as compared to the peripheral membrane 52. Since the hinge is therefore filled first, it will be advantageously strong, and since the portion of the membrane 52 adjacent the hole 26 is filled last, it will be advantageously weak. With the panel 51 sealed by the membrane 52, the closure 10 is sift-proof prior to opening by the consumer or user. The rotor 12 has a circular main body or disc 36 with a central hollow hub or post 37 depending from its lower face designated 38. On an upper face 39 the rotor 12 includes an upstanding chordal finger grip bar 41 to facilitate manual turning of the rotor 12 on the base 11. The rotor 12 is imperforate except for an array of sift holes 42 and a pour hole 43. The array of sift holes 42 and the pour hole 43 have the same eccentricity or distance from the center of the rotor 12 as the dispensing hole 28 has from the base center hole 26 so that these holes 42 or 43 can be alternatively turned into superadjacent alignment with the dispensing hole 28 by manually rotating the rotor 12 on the base 11. A depending flange 44 is formed adjacent the periphery of the rotor 12 at its lower face 38. The flange 44, particularly when the rotor 12 is gated for molding purposes at its periphery, serves to improve molding performance and during use serves to stiffen and maintain the desired flat shape of the rotor. The bottom or underside surface 38 of the rotor 12 is substantially flat between the flange 44 and the hub 37. As shown in FIG. 5, the axial extent of the flange 44 is less than the height of the base ribs 27, 29 so that the flange, when the rotor is assembled on the base, does not touch the web 13. The hub 37 is a thin walled round structure depending from the center of the bottom or lower face 38 of the rotor 12. The lower end of the hub 37 is slightly tapered on its exterior from a minimum diameter slightly less than that of the base hole 26 to facilitate assembly into this hole. In its free state, the hub 37 has a major outside diameter at its mid-section 46 that is greater than the diameter of the hole 26 enabling the hub 37 to be snapped into the hole. Once it is pressed or snapped into the hole 26, the hub 37 is retained in assembly by a rearwardly or upwardly facing annular shoulder 47 that engages the lower edge of the hole 26. Preferably, the outside diameter of the hub 37 above the shoulder 47 is slightly smaller than the diameter of the hole 26 to reduce friction between these areas. The major outer diameter of the rotor 12 is dimensioned to snap past the internal rim shoulder formed by the conical or radial face 21 on the rim 14 into the groove formed between it and the web 13. Typically, the rotor 12 is automatically assembled on the base by a machine known in the art. It can be seen in FIG. 5 that, in assembly, the rotor 12 is retained on the base 11 both at its center and at its periphery. The retention at the center is produced by the interengagement or abutment between the hub shoulder 47 and the lower edge of the hole 26. The retention at the outer periphery of the rotor is provided by interengagement or abutment between the upper face of the rotor 39 and the shoulder 21. The various elements of the base 11 and rotor 12 are proportioned and dimensioned so that the ribs 27, 29 hold the rotor in a flat plane with the upper peripheral rotor edge urged against the rim shoulder 21 and, simultaneously, the hub shoulder 47, urged against the underside of the rotor 12 by the resilient sealing lip 33. The reinforcement bridges 53 and hinge 54 serve to support the panel 51 in its molded hole closing position and resist normally expected forces on the panel that occur during manufacture of the closure including assembly with the rotor and assembly of the closure with a container as well as forces, impacts, etc. occurring during handling and shipping of the container from a filling line to the ultimate consumer of a package. The panel 51 simplifies assembly of the rotor 12 and base 11 since it eliminates the need to orient the rotor on the base at a closed position prior to assembly with a container. When a package is to be opened, a user rotates the rotor 12 to the location where the rotor opening 43 overlies the base opening 28. Preferably using a small rigid object such as a pencil, the panel is pushed downwardly with a force ideally at an arrowhead 58 imprinted on the panel 51. The strength of the bridges 53, progressively one or two at a time, as well as the membrane 52, is readily overcome and broken away and the panel swings downwardly about the hinge 54. The material of the base at the hinge has enough plastic elongation characteristics to allow the panel 51 to move to a plane generally perpendicular to the base web 13 and retain it in this general position. With the panel 51 displaced in this manner, the user can dispense product or rotate the rotor to the sprinkle position where the holes 42 overlie the opening 28 and then eventually turn the rotor 12 to a closed position where its solid area overlies the opening 28. In this position, the sealing lip 33 is pressed against the underside of the rotor to maintain a sift-resistant condition. In a closed position where a solid area of the rotor 12 overlies the dispensing hole 28, the resilient lip seal 33 around the dispensing hole 28 forms a tight sift-resistant seal with the flat underside surface of the rotor 12. The disclosed ribs 27, 29 working with the center and peripheral retention points maintain precise control of the flatness of the rotor 12 to improve the integrity and reliability of the sift- resistant seal. The various parts are dimensioned so that when the rotor and base are assembled, the lip seal 33 is substantially compressed. It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.

Claims

WHAT IS CLAIMED IS:

1. A sift-resistant dispensing closure formed of injection molded thermoplastic material comprising a base and a rotor assembled on the base, the base including a peripheral rim for attachment adjacent an opening in the container and a central web radially inward of the rim for extending across the container opening, the rotor having a disc-like main body with an outer periphery and a center, cooperating retaining elements on the base and rotor supporting the rotor in an assembled position on the base in which the rotor main body overlies the base central web, the retaining elements permitting rotation of the rotor on the base about its center, a dispensing opening in the base web disposed radially between the rim and the center of the rotor, a resilient lip seal surrounding the dispensing opening and engaging an underside surface of the rotor main body, the rotor main body having at least one dispensing opening selectively alignable with or displaceable from the base dispensing hole by manual rotation of the rotor on the body, the retaining elements restraining the rotor for rotation in the plane of the main body and in an axial location where its underside compresses the lip seal to assure a sift- resistant seal therewith at angular positions where the dispensing holes are out of alignment, a breakout panel integrally molded with the base forming a sift-proof seal across the base dispensing opening.

2. A closure as set forth in claim 1, wherein a thin membrane, substantially thinner than the panel, joins the periphery of the panel to the surrounding area of the base.

3. A closure as set forth in claim 2, wherein the membrane extends between the sealing lip and the breakout panel .

4. A closure as set forth in claim 2, including a plurality of reinforcing bridges between the base and the panel, the bridges being joined to the membrane and being spaced along the periphery of the panel.

5. A closure as set forth in claim 4, including a hinge between the base and the panel and joined to the membrane, the hinge being arranged to maintain the panel joined to the base when it is broken out of the dispensing opening.

6. A closure as set forth in claim 2, including a hinge between the base and the panel, the hinge being joined to the membrane and during molding of the base being arranged to admit material forming the panel into the zone of the panel.

7. A closure as set forth in claim 1, wherein the breakout panel is substantially thinner than the base web.

8. A sift-resistant dispensing closure formed of injection molded thermoplastic material comprising a base and a rotor assembled on the base, the base including a peripheral rim for attachment adjacent an opening in the container and a central web radially inward of the rim for extending across the container opening, the rotor having a disc-like main body with an outer periphery and a center, cooperating retaining elements on the base and rotor supporting the rotor in an assembled position on the base in which the rotor main body overlies the base central web, the retaining elements permitting rotation of the rotor on the base about its center, a dispensing opening in the base web disposed radially between the rim and the center of the rotor, a resilient lip seal surrounding the dispensing opening and engaging an underside surface of the rotor main body, the rotor main body having at least one dispensing opening selectively alignable with or displaceable from the base dispensing hole by manual rotation of the rotor on the body, the retaining elements restraining the rotor for rotation in the plane of the main body and in an axial location where its underside compresses the lip seal to assure a sift- resistant seal therewith at angular positions where the dispensing holes are out of alignment, a breakout panel integrally molded with the base forming a sift-proof seal across the base dispensing opening, a relatively thin membrane extending between the resilient lip seal and the periphery of the panel, a plurality of reinforcing bridge elements spaced along the periphery of the panel extending between the resilient lip seal and the panel, and a hinge element extending between the resilient lip seal and the panel.

9. A closure as set forth in claim 8, wherein the web of the base has a gate area, the hinge is on a side of the panel remote from a gate area, and the base has a mounting area for the rotor disposed between the panel and the gate area, the mounting area deflecting plastic material being formed into the base when it is being molded away from a proximate area of the panel and towards the hinge.