Patent Application
20060243733
This invention relates to containers for liquids and is particularly concerned with a container intended for use with paint and similar materials. It will be understood that the invention is directed to the structure of a container, and is not limited to use with any particular contents. Obviously the purpose of a paint can is to contain paint in a condition that prevents unintended release or removal of the liquid from the bucket, while allowing convenient access to the liquid when desired. A paint can requires a rugged, reliable, sealing engagement between the top of the bucket and the cover. Simultaneously, access to the can's contents requires the cover to release its engagement with the bucket upon reasonable, directed effort on the part of the user. These somewhat contradictory requirements have more or less been resolved in satisfactory fashion over the years for traditional metal paint cans. Recently, however, for reasons of cost and convenience, paint cans integrally molded from plastic materials have become competitive with the metal paint can.
Paint cans have traditionally been provided with a carrying handle and plastic paint cans are no exception. Metal cans usually had a handle in the form of a wire bail. The bail was a separate piece that was pivotally attached to the bucket. The ends of the bail were received in receptacles attached to the bucket to form a hinge. It is preferable in plastic cans not to have the handle formed as a separate part, due to the extra manufacturing step of attaching such a handle to the bucket and due to the problems of assuring that a separate handle remains connected to the bucket. Thus, the handle is integrally formed in plastic paint cans. However, this has also proven to have its share of problems in prior molded paint cans. Such buckets have a generally semi-circular handle fastened to opposite sides of the bucket near the top edge of the bucket at attachment anchors. Living hinges are formed at the junctions of the handle and anchors. The molding process used in prior art cans formed the handle by feeding molten plastic material into a mold cavity from the bucket floor, into the walls, through the two attachment anchors and into the handle cavity from both ends. The plastic material feeding into the handle cavity from the two anchor areas would meet some-where in the arcuate extent of the handle cavity, typically somewhere near the middle. These two separate bodies of plastic material feeding into the handle cavity would then have to blend together or knit to form the complete handle. While this can be accomplished under carefully controlled molding conditions and with properly selected grades of materials, doing so can increase the cost of the paint can due to the need for more expensive molding equipment, slower cycle times and increased material costs. More importantly, it has been found that molding the handle by attempting to knit two bodies of plastic fed from separate directions can lead to handle failures when optimum conditions and materials are not utilized. When such handle failures occur, particularly with an open bucket at a work site, the results are not favorable for either the painter or the paint supplier. Particular unpleasantries are reserved for the paint can manufacturer when the knit handle fails. The present invention resolves these issues by providing an improved molded paint can.
The present invention concerns a paint can that can be molded of plastic material. A primary object of the invention is a paint can having a knit-free handle attached to the bucket by knitting the handle anchors to the walls of the bucket.
The paint can has a bucket and cover which are releasably engageable with one another. The cover has sealing elements that cooperate with the upper edge of the bucket. Inner and outer sealing walls on the cover receive the top land of the bucket. The bucket is molded by feeding molten plastic material into a mold cavity both from two separate gates in the mold. The two gates feed into mold cavities for the floor of the bucket and from the center of the handle. The fed materials meet somewhere in the side walls of the bucket so the two streams knit together at a point remote from the handle itself. This forms a knit free handle and places the knit locations at a point where the loads on the container will be spread out over the greatest area.
These and other desired benefits of the invention, including combinations of features thereof, will become apparent from the following description. It will be understood, however, that a device could still appropriate the claimed invention without accomplishing each and every one of these desired benefits, including those gleaned from the following description. The appended claims, not these desired benefits, define the subject matter of the invention.
The paint can of the present invention includes a bucket and a cover or lid. The bucket 10 will be described in conjunction with
The bucket further includes a cylindrical wall 18 that extends upwardly from the outer edge of the floor 12 to an upper, open end. The wall joins the floor at a junction 19. The wall 18 has an inner face 20 and an outer face 22. At the upper end on the inner face there is a very slight indentation formed by a mold parting line 24 (
A pair of handle anchors 42, 44 are attached to the upper end of the bucket wall. In a preferred embodiment the anchors are formed on the outer edge of the reinforcing ring 34, as seen in
The construction of the handle and in particular the central portion 50 is noteworthy. As best seen in
A suitable cover (not shown) will be provided to close the open end of the bucket. The cover forms no part of the present invention.
A variety of plastic materials may be suitable for the bucket. A preferred material for the bucket is a polypropylene copolymer. However, it will be understood that substitutions for this material could be made without departing from the scope of the present invention.
The process for molding the bucket is as follows. A mold is prepared that has cavities for forming the floor, the wall including its upper end portion, the handle anchors and the handle. The cavities are in fluid communication with one another so the entire bucket is molded at the same time. Specifically, the handle cavity communicates with the anchor cavities which in turn communicate with the cavity for the upper end portion of the wall, including the reinforcing ring. The wall cavity communicates with the floor cavity. For these purposes the foot may be considered part of the floor. The mold cavities are filled from two gates, one located at the floor dimple 14 and one formed at or near the central portion of the handle. Molten plastic material is fed from both of these gates. The feeding process is controlled so that while the majority of the material is fed through the floor gate, all of the material forming the handle and handle anchors is fed through the handle gate. Thus, the handle material enters the handle gate and flows in two directions from the gate through the handle cavity, into the handle anchor cavities and tabs and from there into the reinforcing ring portion of the wall cavity. Floor fed material joins or knits with the handle fed material in the wall cavity, in the vicinity of the handle anchors but spaced from the handle anchors. Accordingly, no knitting of material occurs in the handle cavity. The handle is free of knitted areas or zones. There are knit zones in the walls. However, the knitting that occurs in the walls is in areas of lesser stress concentration than the handle and thus there is a reduced chance of failure than if there were a knit zone in the handle. This molding process greatly reduces the chances of handle failures while also reducing cycle times by decreasing the amount of time it takes to fill the mold.
While the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, substitutions and alterations thereto. For example, while the anchors are shown attached to the reinforcing ring, they could be attached directly to the wall of the bucket. That is, the reinforcing ring may be located spaced from the anchors. Or in certain circumstances it may be possible to delete the reinforcing ring altogether. Thus, the knitting of molten plastic material may take place in the reinforcing ring, if there is one, or it may take place in the bucket wall, whether the reinforcing ring is present or not. What is important is that the knitting does not take place in the handle cavity. Also, while the bucket wall is shown as completely cylindrical, it need not have this exact shape. It could have a conical portion or it could include hand grips formed in the sides.
