Thermoplastic Container Closure for Dispensing Solids

The present invention is for a container closure which, when affixed to a container that holds finely divided solid material, will selectively provide a clean and sanitary closure and a convenient dispensing means for the contents of the container. The closure is easy to mold from thermoplastic material, and is an integral unit. It is unique because it is devoid of any ridges or recessed areas on the container top surface, so that when it is applied to a container the assembly has no areas for the collection of dust or fine solid particles.

Numerous plastic closures are found in the art which can be used in dispensing solid material. Examples of such prior art plastic closures are illustrated in U.S. Pat. Nos. 3,140,019; 3,493,150; 3,499,588; 3,836,056; 3,966,080; 4,106,672; 4,209,100 and 4,223,814. As will be seen by reviewing these prior art references, they all have some type of recessed portion in the container top surface within which a hinged closure flap is seated, or some type of recessed walled area, which recessed portion or walled area will, over a period of time serve as a collection point for dust or other unwanted fine solid particles. Even in closure, such as described in U.S. Pat. No. 3,675,812 where a raised portion is provided on the container top, various walls are provided, either on the closure flap or on the container top surface with which the flap mates, which serve to collect dust or the like.

In the present thermoplastic container closure, only raised surfaces are provided along the top of the closure, so that the tendency to accumulate dust in recessed areas which is difficult to remove is obviated.

A thermoplastic container closure, for use in dispensing finely divided solid material from a container to which the closure is secured, comprises an annular substantially planar base with a downwardly extending substantially cylindrical wall, the wall having attachment means such as a thread for attachment to a container with a neck, the rim of which seals against and supports the underside of the annular base, the base having a raised platform thereon which forms a first planar surface parallel to the base, which platform has at least one dispensing aperture therethrough and an upstanding shoulder at one end thereof, and a closure flap hingedly attached to the shoulder, which flap has at least one projection frictionally engageable within the apertures in the platform, such that when the flap is closed, with the projections frictionally engaged within the apertures, the closure flap and upstanding shoulder form a second planar surface which is substantially parallel to both the platform and the base.

The present invention will be more fully understood by reference to the accompanying drawings, wherein:

FIG. 1 is a top plan view of the container closure of the present invention with the flap in closed position;

FIG. 2 is a top plan view of the container closure of FIG. 1 with the closure flap in open position;

FIG. 3 is a bottom view of the container closure of FIG. 1 with the flap in closed position;

FIG. 4 is a cross-section taken along the lines IV--IV of FIG. 1;

FIG. 5 is an enlarged cross-sectional fragmentary view taken along the lines V--V of FIG. 2, showing the hinge area of the container of the present invention with the flap in open position as in FIG. 2; and

FIG. 6 is a cross-sectional view of the container closure, as in FIG. 1, engaged with a container.

Referring now to the drawings, FIG. 1 illustrates a top plan view of the integral, releasable, thermoplastic container closure 1 of the present invention having a substantially planar circular base 3 with a downwardly extending wall 5 about its periphery, sometimes referred to as a "skirt". As illustrated in FIG. 4, the downwardly extending wall 5 have attachment means, such as a thread 7 on the inner surface thereof, to releasably attach the container closure to a container 9. Although a thread 7 is illustrated in the drawings, for use with a container 9 having a cooperating thread 11 on the neck thereof, it is to be understood that the downwardly extending walls may have other attachment means, such as a groove which would frictionally engage a rib on the container neck, or other frictional attachment means known in the art. When the cap is applied tightly in place on the container, the neck of a bottle or jar to which it is applied is encircled by said depending skirt and the lip of the container neck forms a seal against and support for the undersurface of the base 3 within the circumference of the base 3 and said depending wall.

The circular base 3 has a raised platform 13 thereon, which platform 13 comprises a first elevated planar surface 15. This first planar surface, sometimes herein also referred to as the "lower elevated area" is in a plane parallel with the base. The platform is supported on the base by a vertical wall or flange 17 that extends completely around the inner periphery of the base. This first platform has at least one product dispensing aperture a therethrough, and usually there will be a group, three being shown in the drawing, but the size and number may vary. They may sometimes be termined "sifter openings". They are simply clean holes through the thickness of the platform with no upstanding ridge or depending skirt above or below the plane of the platform.

Extending across the raised area 15 in the position of a chord of the base circle there is an integral riser or step 25 dividing said raised areas 13 into said lower elevated area or first platform and a higher elevated area or shoulder 19 forming a second platform 21, the higher curved boundary 23 of which is an integral part of the circular vertical wall 17. A diameter that bisects this step into equal halves would, of course, be at right angle to the chord of the circle defined by the step 25 and this diameter would bisect the center opening a in a group of such openings, establishing the location of this and the other openings in the lower elevated area 15 in that portion of the platform which is furthest removed from the step 25. The upstanding shoulder 19 has an outer wall 23 which is complementary with the wall 17 of the raised platform 13, and an inner wall 25. Hinged to the upstanding shoulder 19 is a closure flap 27. The closure flap 27 is hingedly attached to the upstanding shoulder along the upper edge of the wall 25, by a hinge 29 that is formed by thinning to a flexible membrance the edge of the flap 27 along the connection thereof with the upstanding shoulder 19. The closure flap has a substantially planar upper surface 31 and a lower surface 33, the lower surface 33 having at least one projection 35 thereon, which projections mate with the apertures a in the platform 13 when the flap is in closed position. The upper edges of the apertures a may be bevelled and the projection 35 shaped so as to frictionally engage the walls about the apertures a to provide a force fit to frictionally but releasably retain the flap 27 in closed position. The apertures a and the projections 35 are preferably all located respectively in the first raised area 15 and remote from the hinge at the step 25, that is in an area diametrically across from and physically remote from the higher surface 21. At this location the arc of travel of the projections will more closely approach parallelism with the axes of the several holes as they approach a closing position than if they were closer to the hinge and therefore moving in a sharper curve. This location also enables the flap 27, when closed, to constitute a continuous planar surface with the higher level of surface 21 and avoid any crevice. The hinge line shown in the drawing, FIG. 1, is actually a concealed unbroken surface showing at most a crease line. When the flap 27 is fully closed, its undersurface, except where the projections pass through the sifter holes, is in full face-to-face contact in a plane parallel with the base.

With the flap 27 in closed position, the projections 35 being frictionally engaged to seal the apertures a, the upper surface of the closure 1 is comprised of only two parallelly planar surfaces, the first surface comprising the substantially planar base 3, and the second or raised surface comprising the planar surface 21 of the raised shoulder 19, and coplanar surface, the planar surface 31 of the flap 27.

Preferably, the container closure of the present invention, as illustrated in the drawings, is a cylindrical-shaped closure, with the upper surfaces thereof forming concentric circles. The edge of the platform 13 opposite the shoulder 19 is preferrably indented as at 37, so as to enable the user to reach under the flap 27 to readily raise the flap 27 and dispense the contents of the container through the apertures a.

The container closure of the present invention thus provides raised surfaces which are on parallel planes so as to prevent accumulation of dust. In addition, the planar surfaces enable easy and secure stacking of the container closures alone, or when secured to containers, one container having a closure upon another container with its closure that is, end-on-end, for shipment or storage. While the closure flap 27 may open and close quite easily, it should not open spontaneously. Because of this, there is a natural tendency for the user to press down on the flap with much greater force than necessary. Since the cap is formed of thermoplastic resin, it possesses flexibility that thermosetting resins do not have. It is not feasible in this or like products to increase the thickness of the thermoplastic resins to materially increase their rigidity. Not only are the closures subject to pressures as above pointed out, but they also are subject to stacking when the containers are filled and are being shipped or are in storage. By having the base of the closures supported directly on the lip of the vessel, destructive leverage tending to distort or rupture the base of the closure is reduced. Also, by all horizontal surfaces being parallel and at right angles to the axis of the closure, downward pressures are uniformly transmitted to the base, and to the lip of the container especially, by vertical walls in a generally columnar direction. Moreover, that central area of the closure which is pushing down on the flap and is farthest from the rim is reinforced by the double thickness of the flap and lower elevated area in face-to-face contact.