Plastic Container And Method Of Making The Same

Abstract

A plastic container has a cylindrical body member and a bottom member which are separately molded. The body member is formed with an open bottom and has an annular groove in its bottom edge. The bottom member has a pair of concentric upstanding annular flanges, the outer one fitting within the annular groove in the bottom edge of the body member, and the inner one fitting within the open bottom of the container to abut the lower portion of the interior wall thereof. The parts are permanently sealed to each other by ultrasonic welding, usually after a bottom-filling operation with the container in an inverted position.

Description

BACKGROUND OF THE INVENTION

This invention relates to the manufacture of plastic containers and, more particularly, to plastic containers wherein the body portion of the container is made with an open bottom and a bottom wall is subsequently attached thereto.

Plastic containers molded by various methods such as injection molding, blow molding, and otherwise, are of course in widespread use.

In many plastic containers the bottom wall is molded integrally with the side wall or body of the container but the present invention relates particularly to containers wherein the container body and the upper end or neck portion thereof are molded integrally with the bottom end of the container open. In such containers the bottom member is subsequently applied.

This type of container is employed in cases where the upper end construction of the container has a relatively constricted neck formation and wherein the body, including the upper wall structure, is desired to be injection molded.

A particular area wherein containers with separate later-applied bottom members are desirably employed is in the field of aerosol containers wherein the contents of the container and the propellant are deposited in the container with the same in inverted condition, the contents and propellant being deposited in the container before the bottom wall is applied.

In containers having separately applied bottom wall members, the joint between the container body and the bottom wall is frequently inadequate structurally and hermetically. When containers of this kind are dropped, they commonly plummet downwardly bottom first and usually land angularly on the bottom rim of the container with the frequent result being leakage of the joint between the container body and bottom. In fact the pressure of the contents under impact dropping of the container as heretofore constructed sometimes blows the bottom completely from the container body.

SUMMARY OF THE INVENTION

In the present invention the container body or side wall is generally cylindrical and is formed about its lower edge with a groove which receives an annular tongue formation on the bottom element. This much is known in the present art and the container construction of the present invention also includes an upstanding annular flange on the bottom member which engages the lower interior wall of the container body, and which in effect backs up the tongue and groove joint to prevent loosening of this joint by impact, as when the container is dropped. More importantly, this upstanding flange prevents internal pressure in the container from having direct access to the tongue and groove joint per se, which joint has heretofore been the weakest point in container constructions of this general type.

The bottom construction of the present invention, including the tongue and groove joint and the additional internal flange which rigidifies the same, is also highly effective in autogenously welding the bottom to the container body as by ultrasonic vibration of the parts since the parts are fixed to each other throughout the tongue and groove construction, and also throughout at least a portion of the abutting surfaces of the interior wall of the container and the adjacent internal upstanding flange of the bottom member.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a general elevational view of a plastic aerosol container having a bottom wall construction in accordance with one form of the present invention; and

FIG. 2 is an enlarged view of the lower portion of the container of FIG. 1 shown inverted and partly in cross section to illustrate the interfitting connection between the side wall of the container and the bottom wall thereof.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

In FIG. 1 the numeral 10 designates a generally cylindrical container body having a bottom wall member 11 and an aerosol dispensing means 12 at the upper end thereof. FIG. 2 shows the lower portion of the container of FIG. 1 on a considerably enlarged scale and in an inverted position, in which position the container is filled through its open bottom and then provided with the bottom wall member of the present invention.

In the form shown in FIG. 2, the generally cylindrical side wall of the container may be injection molded or otherwise formed of plastic material and the side wall flares toward its lower edge to provide a lower edge portion of increased thickness. An annular groove 14 having flaring side walls is formed in the bottom edge of container body 10 and groove 14 has an annular enlargement or extension at its outer portion as shown at 15 in FIG. 2.

Bottom wall 11 has a tongue formation 16 which fits snugly into groove 14 and an annular flange formation 18 which fits within the wall of container 10 and abuts the lower interior portion of such wall as shown in FIG. 2. The numeral 20 designates one of a series of circumferentially spaced vertical grooves of generally semi-circular cross section which are provided for purposes having to do with the filling and evacuating of the interior of the container and are not otherwise involved in the present invention.

Excepting where interrupted by the grooves 20 the internal flange 18 seats against the interior wall of container 10 for substantially the full height of flange 18. The tongue 16 and annular flange 18 define in bottom 11 an annular groove which fits over the flange or rib 21 at the bottom of container 10 at the interior wall thereof adjacent to flaring groove 14.

Tongue and groove joints for container bodies are not broadly new but the construction of the present invention differs therefrom in providing the additional internal flange 18 which abuts against the interior of container body 10 and thus stiffens the same and militates against loosening of the tongue and groove joint 14, 16, particularly against impact forces from the outside of the container body and bottom as when the same is dropped.

In FIG. 2 the container is shown fragmentarily in the inverted position after the material to be dispensed and the propellant have been placed in the container through the open bottom and after such other treatment as partial evacuation has been performed. Bottom member 11 is shown in its finally assembled position ready to be permanently sealed to body 10. The numeral 25 designates the horn of an ultrasonic vibration apparatus by means of which the abutting surfaces of the container body and bottom 10 and 11 are fused or welded. Horn 25 in the present instance comprises a cylindrical member having a radial end face which is pressed against bottom member 11 to transmit ultrasonic vibration to the assembly and produce the required welding.

This welding fuses all of the abutting surfaces of tongue 16 of bottom 11 with groove 14 of body member 10 and ordinarily this welding or fusion will extend approximately halfway along the abutting surface of flange 18 and the interior of container 10. The welding or fusing operation may produce a slight flash or roughness at the edges of the welded surfaces and the auxiliary groove portion 15, shown in FIG. 2, insures a smooth bottom finish for the container even through some of the plastic material may ooze from the welded surfaces as at the deepest part of groove 15.

A preferred embodiment of the present invention has been described and illustrated herein to illustrate the principles of the invention but it is to be understood that numerous modifications may be made without departing from the broad spirit and scope of the invention.

Claims

We claim:

1. In a plastic container for pressurized contents, a body member comprising a generally cylindrical wall formed with an open bottom end and having a bottom wall member secured thereto, said body member bottom end having an annular groove therein, said bottom member having an annular flange formation fitting snugly within said groove and a second concentric flange fitting within the said bottom end of the container body with the outer surface of said second flange in abutment with the lower portion of the interior surface of said container body to reinforce the same against external impact forces, said body member and said bottom member being sealed to each other at least in the area of said first flange formation.

2. A plastic container according to claim 1 wherein said sealing of the body and bottom members extends from said first flange formation inwardly and along at least part of the abutting surfaces of second flange and the interior surface of the container body.

3. A plastic container according to claim 1 wherein said members are sealed by an autogenous weld.

4. A plastic container according to claim 1 wherein said members are sealed by an ultrasonic weld.

5. A plastic container according to claim 2 wherein said members are sealed by an autogenous weld.

6. A plastic container according to claim 2 wherein said members are sealed by an ultrasonic weld.