Dispensing – With discharge assistant – Container with follower
Patent
1983-06-01
1985-12-03
Rolla, Joseph J.
Dispensing
With discharge assistant
Container with follower
222389, 222327, B67D 542
Patent
active
045561567
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a container adapted to dispense its contents under pressure. Particularly, but not exclusively, the invention is concerned with the dispensing of viscous materials from a container under pressure of a propellant.
A vast range of materials are routinely dispensed from pressurised containers of the commonly named "aerosol" type. In such containers the material to be dispensed ("the product") lies within the container either in admixture with or in solution in the propellant. This technology, therefore, is suitable only for dispensing products which do not interact with or deteriorate in the presence of the propellant. Also, such containers normally dispense the product as a fine mist but they can be adapted to dispense the product as an unbroken liquid stream.
A small number of special container designs are known for dispensing products which have to be held out of contact with the propellant. There are, generally speaking, two types of these containers, the "collapsible bag" type and the "piston" type. In the collapsible bag arrangement the product is held in a flexible bag secured to the neck of the container with an outlet valve extending outwards for exit of the product; the propellant is held between the bag and the container wall. Under pressure the bag collapses and extrudes the product from the exit valve. Problems with this arrangement are that the bags are permeable to the propellant causing bubbles to form in the product, and also the bags tend to collapse in an unpredictable manner and incompletely, which leaves amounts of the product trapped therein and unusable.
In the "piston" type the container is divided into two chambers by an internal piston, product is held on one side of the piston and propellant on the other. Under pressure of the propellant the piston forces the product from the container.
We have carried out much investigation over several years into the operation of the piston type of dispenser and the operational problems thereof. They are not common in the market-place; those which are available appear to satisfy their specific uses but one major problem prevents their unrestricted general application to products of any kind. That major problem is penetration of the propellant into the product. If the presence of the propellant deteriorates the product, and many materials are affected adversely then the known packs cannot be used. Even if the product is chemically inert to the propellant, the propellant may nevertheless from gas bubbles in the product and break up the extruded stream of product.
The present invention provides a piston type of dispenser which can be used for dispensing any material but its development was undertaken to dispense semi-solid mastics, adhesives and silicone sealants most of which are extremely sensitive to contact with the propellant.
Many mastics, sealants and adhesives are available commercially is small packages in squeeze-tube packs and in larger quantities in cylindrical tubes, one end of which is formed by a slidable piston. In use, a manually operable "skeleton gun" is supplied which clamps around the tube and by exerting pressure by a screw twist or by a trigger actuated pump action the piston is forced manually through the tubular container. The main difficulties with this arrangement are the cost of the gun and the difficulty of maintaining a constant manual pressure in order to extrude a stream of product of uniform dimensions while at the same time guiding the stream of product along a line of application.
British patent application No. 2015655 to Schumacker describes a dispenser for liquids and pastes in which there is provided a container having therein a piston, which is propelled by gaseous propellant, having first and second wall-engaging skirt portions and therebetween a number of wall-engaging scraper rings. Held between two adjacent scraper rings is an elastic or flexible ring made of foam. It is thought that such an arrangement would not provide a barrier of sufficient impenetrability to passage of propella
REFERENCES:
patent: 2649995 (1953-08-01), Muskin
patent: 3273762 (1966-07-01), O'Neill, Jr.
patent: 3430731 (1969-03-01), Satzinger
patent: 3756476 (1973-09-01), Bonduns
Noland Kenneth
Rocep-Lusol Holdings Limited
Rolla Joseph J.
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