Dispensing – With discharge assistant – Container with follower
Reexamination Certificate
2001-07-23
2004-06-08
Derakshani, Philippe (Department: 3754)
Dispensing
With discharge assistant
Container with follower
C222S389000
Reexamination Certificate
active
06745920
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to pistons, to precursors for making containers, to containers, to product-containing containers, to methods of making such pistons, precursors, containers and product-containing containers, to methods of dispensing, and to methods of filling containers. In another aspect, the present invention relates to pistons for pressure operated dispensing containers, to pressure operated dispensing containers utilizing a piston longitudinally slidable within the container, product-containing containers, to methods of dispensing, and to methods of filling. In even another aspect, the present invention relates to pistons for pressure operated dispensing containers, to pressure operated dispensing containers utilizing a piston longitudinally slidable within the container, product-containing containers, to methods of dispensing, and to methods of filling, all of which provide improved resistance to “leak through” of product past the piston.
2. Description of the Related Art
Pressure operated dispensing containers which utilize a piston longitudinally slidable within the container are well known in the art. These types of containers are used to dispense any number of products, for example many consumer products such as shaving gels.
Such a pressurized container is generally cylindrically shaped, and includes a movable piston disposed therein, which divides the container reservoir into two chambers, i.e., the chamber above the piston or the “upper chamber” wherein the product composition resides, and the chamber below the piston or the “lower chamber” wherein the compressed fluid is injected or pressure filled. Said compressed fluid is at a pressure higher than ambient and higher than that of the product in the upper chamber. A dispensing valve is positioned to be in liquid communication with the product containing composition compartment, to allow for dispensing of the product composition for use.
The piston is roughly in the form of an inverted cup, with a curved surface designed to closely match the inside-top of the container such that in its penultimate position at the top of the container, the piston will have forced and dispensed essentially all of the product composition in the upper chamber through the dispensing valve. This helps in minimizing product composition left unused or undeliverable inside the container. In addition, the piston has an upper and an annular skirt or sidewall which extends down from the upper surface. The upper surface acts as a barrier to separate the product from the gas. The annular sidewall of the piston stabilizes and positions the piston in the container and provides a surface which rides on the inner wall of the container.
While the exact details of loading may vary from industry-to-industry and product-by-product, the following is a general description. The product to be dispensed is loaded into the upper chamber of the container under pressure. The loading is a three stage operation, with each stage occurring at a different index position on the loading machine. During the first stage, known as the fill stage the product is introduced into the can above the top of the piston. During the second stage, known as the pressure stage a pressure differential is created above and below the piston to force some of the product down around the periphery of the piston between the piston sidewall and the container. During the third stage, known as the pushup stage, the piston is pushed toward the top of the container. This pushup stage also causes product to seep down around the periphery of the piston. After the loading of the product into the upper chamber is completed, propellant is loaded into the lower chamber under pressure. In use, when the valve at the top of the container is opened, the propellant pushes the piston toward the top of the container through the valve.
In operation of, for example, a pressurized container of shaving gel, a user will activate the product dispensing valve, whereupon the pressurized gas will urge the piston to move against the product, thus urging the product out of the dispensing valve.
One major problem with these type of pressurized containers is that the product may slip past the piston into the pressurized gas compartment (sometimes referred to as “leak through”). Specifically, prior art pistons have not been entirely satisfactory during both the loading of the pressurized container and during the dispensing of the product therefrom.
The following are some of the numerous patents directed to pistons for aerosol containers.
U.S. Pat. No. 3,132,570, issued May 12, 1964, to H. T. Hoffman, Jr., et al, discloses a piston construction for an Aerosol Container.
U.S. Pat. No. 3,245,591, issued Apr. 12, 1966, to R. H. P. Kneusel, et al, discloses a dispensing piston can.
U.S. Pat. No. 3,381,863, issued May 7, 1968, to E. J. Towns, discloses a piston for use in pressurized dispensing containers and more particularly to a piston for use in pressurized dispensing containers in which the propellant is separated from the goods to be dispensed. The piston includes a number of flanges, which the patent teaches are of generally diminishing thickness from the flange's portion of greatest diameter to its portion of least diameter to avoid “wrinkling” when the piston is engaged in a can. Disposed on the end of the flanges are thin skirts which more easily adopt the configuration of the container's interior surface than the thicker portion of the annular flanges. The outside diameter of the flange as measured on the piston prior to insertion in the can is greater than the inside diameter of the can.
U.S. Pat. No. 3,407,974, issued Oct. 29, 1968, to L. J. Chmielowiec, discloses a dispensing container having piston-bag structure.
U.S. Pat. No. 3,433,134, issued Mar. 18, 1969, to P. B. Vellekoop, discloses a piston for use in an aerosol can having an outer tubular container provided with a propellant gas therein. The piston has a cylinder provided with a centrally concave wall together with a centrally disposed disk. A plurality of supports join the cylinder and the disk and are equally spaced at an angle of approximately forty-five degrees to each other. The wall supports are arranged in vertically aligned pairs and extend along the disk substantially one-half the radius thereof. The cylinder has upper and lower wiping edges defined by the concave wall and the entire piston assembly may be integrally molded from a synthetic plastic material.
U.S. Pat. No. 3,901,416, issued Aug. 26, 1975, to Robert S. Schultz, discloses a piston-operated pressurized container adapted for top-loading with viscous foods or other viscous products, the body of the piston having a substantially smaller diameter than the diameter of the container. The outer periphery of the piston is provided with a resilient flange member that maintains a light sealing pressure on the interior surfaces of the container, allowing the piston to move upwardly within the container. The inventive method provides enhanced assurance against product leakage and against propellant-contamination of product, prior to selective product discharge as desired.
U.S. Pat. No. 3,987,941, issued Oct. 26, 1976, to Alfred V. Blessing, discloses a container for cooked liquid food substances in which there is provided a follower lid or upper cover capable of following the level of the liquid as the food substance is removed from the container. The invention includes a particular construction of lid and seal that allows for free upward and downward movement of the lid in contact with the liquid as the liquid level changes. In this manner, the liquid is not in contact with air which would cause its contamination and loss of flavor.
U.S. Pat. No. 4,023,717, issued May 17, 1977, to Schultz, discloses a pressurized container for viscous foods or other viscous products in which the body of the piston includes an axially intermediate flexible circumferential band which lightly contacts or is expandable in the presence of
Derakshani Philippe
Gilbreth J. M.(Mark)
Gilbreth Mary A.
Gilbreth & Associates P.C.
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