Dispensing – Axially slidable tubes – sleeves – or apertured caps – Axial discharge
Reexamination Certificate
2002-08-16
2003-09-16
Derakshani, Philippe (Department: 3754)
Dispensing
Axially slidable tubes, sleeves, or apertured caps
Axial discharge
C222S541600, C222S571000
Reexamination Certificate
active
06619517
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dispensing closure assembly for liquids of various viscosity. More specifically, the present invention is directed to a single dispensing closure assembly for precisely dispensing anaerobic adhesives and sealants of various viscosities.
2. Description of the Related Art
Various designs for fluid dispensing closure assemblies are known which dispense the contents of a container over which the dispensing closure assembly is placed. Additionally, these closure assemblies provide for sealing the container between usages. These dispensing closure assemblies generally include a stationary cap which is attachable to the container of fluid and a cover which is movable with respect to the cap so as to open a dispensement passageway through the assembly and thereby place the contents of the container in fluid communication with a dispense opening in the cover so that the fluid may be dispensed. Such dispensing closure assemblies may be either twisted open and closed or pushed-pulled open and closed so as to effect the relative movement of the cap and cover. Many known dispensing closure assemblies also permit relative movement of the cap and the cover so as to vary the dispense opening so as to increase or decrease the flow rate of the dispensed fluid.
In addition to accounting for viscosity considerations, the nature of the fluid to be dispensed should also be considered. For example, since certain adhesives, such as cyanoacrylates, cure in presence of moisture, while others, such as anaerobics, cure in the absence of oxygen, the dispenser should be designed with the ability to accommodate the particular requirements of the adhesive to be dispensed while also providing a convenient method of selecting an appropriate and versatile means for doing so.
Anaerobic adhesives are characterized by curing in the absence of oxygen through contact with active metals, such as iron and copper. Many of the existing dispensing closure assemblies for anaerobic adhesives allow active metal contaminants thereinto through the dispense opening during the course of dispensing the adhesive. These contaminants have the deleterious effect of accelerating the curing mechanism in adhesive still contained within the dispense passageway which results in eventual blockage of the dispensing closure assembly. Once this occurs, an operator usually cuts such dispense assemblies proximal to the cured blockage in order to again allow for dispensing of the adhesive from the container. Cutting a dispensing closure assembly, however, may result in a differently-sized dispense orifice and thereby significantly change the dispense characteristics for the assembly. The drawback of contaminants into the dispensing closure assembly can be minimized by tailoring the size of the dispense orifice to the viscosity of the fluid being dispensed so as to provide for precise metering of the fluid therethrough. These problems are multiplied when the dispenser is involved in assembly-line operations such as in the automotive or electronics industries.
Adhesives as a general class of fluids useful in the present invention, however, exhibit a wide variety of viscosities, ranging from a fluid being less viscous than water to a flowable paste. The actual rheology of the adhesive used will depend on the intended application. Dispense assemblies having only a single-size dispense orifice may precisely dispense a bead of adhesive when the viscosity of the adhesive is suited to the geometry of the dispense orifice provided. If the same dispensing closure assembly is used for a different adhesive, however, the geometry of the dispense orifice may neither adequately contain adhesives having a lower viscosity nor adequately dispense adhesives having a higher viscosity. Additionally, it is generally desirable to provide a dispensing closure assembly which may accommodate a range of fluid viscosities so as to reduce the manufacturing costs of producing unique dispensing closure assemblies for fluids of narrow ranges of viscosities.
Towards this end, known dispensers have often attempted to accommodate a wide range of viscosities by providing dispensing closure assemblies having a range of selectably-sized dispense openings at the dispense tip. One such example is shown in U.S. Pat. No. 5,501,377, where a dispensing closure assembly includes a central cylindrical sealing post which is variably positionable within a conical or tapering cover wall so as to provide a full range of dispense opening areas at the dispense orifice. For a fluid of a given viscosity, precise dispensement thereof through a series of assembly closures and openings is suspect due to the fully variable cross-sectional area which may be provided at the dispense orifice. That is, the user is unlikely to precisely select an appropriate dispense opening area each time the dispensing closure assembly is opened.
Another example is shown in U.S. Pat. No. 4,927,065, which provides a dispense orifice of discretely changing dispense orifice sizes by positioning a central sealing post having a series of steps formed at its distal end within a cover having a cylindrical dispense aperture. From a closed position where the post extends through the dispense orifice, the post is withdrawn through the cover so as to place different-size steps within the dispense orifice to vary the geometric configuration at the dispense orifice. While providing a more repeatable variation in the dispense orifice, such a design may not be suitable for dispensing anaerobic fluids due to the contamination risk from the post extending out from the cover in the open position. The post is likely to contact the surface to which the adhesive is being applied and to collect particles of that surface which may, in turn, cure the adhesive on the post. For example, particles of brass or other active metals that collect on the post can cause the adhesive thereon to cure very quickly. Adhesive curing on the steps of the post will change the diameter of the post at that location, and thereby affect the dispensing characteristics of the dispensing closure assembly. Furthermore, as the post is exposed during application of the adhesive, the post is more susceptible to being bent or damaged. This too prevents precise dispensement of a fluid. And, from a manufacturing standpoint, it is often times difficult to mold a thin post having a complex geometry at its distal end due to the manner by which such molds accept the moldable plastic and by which the post is withdrawn from the mold in a direction towards its proximal end.
In addition, such designs may not be suitable in many applications because in the course of accommodating a wide range of viscosities, the user is left with more options than may be desirable for day-to-day applications in which precise metering of an adhesive is of paramount importance. For example, when a dispensing closure assembly allows a user to select between three dispense opening sizes depending upon the type of fluid to be dispensed, each time the user opens the dispensing closure assembly there is a risk that the user may incorrectly select an incompatibly-sized dispense opening. Should the user select too large a dispense opening for a low viscosity fluid, far too much fluid may be dispensed onto a high cost component which must then be either cleaned or discarded. The likelihood of the user selecting an incompatibly-sized dispense opening is higher still in manufacturing environments where the operator opens and closes the dispensing closure assembly many times during the course of use.
Furthermore, in many dispensing closure assemblies of the prior art, it is common for residual adhesive to cling to the dispense tip after use. Once the container, including the dispensing closure is uprighted, the residue adhesive will drip down the outer surface of the dispensing closure cover. Since many dispensing closure covers are manually actuated to move from an open to a closed position, it is quite common for the user t
Montenieri Robert E.
Vakiener Brian R.
Bauman Steven C.
Derakshani Philippe
Henkel Loctite Corporation
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