Coating implements with material supply – Including means to apply material-moving force – Including pressurized reservoir
Reexamination Certificate
2000-01-11
2001-09-11
Walczak, David J. (Department: 3751)
Coating implements with material supply
Including means to apply material-moving force
Including pressurized reservoir
C401S222000, C222S386500, C222S399000
Reexamination Certificate
active
06287035
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the dispensation of fluids from a reservoir and particularly, but not exclusively, to the dispensation of ink in writing implements.
2. Description of Related Technology
There are a number of conventional techniques for delivering ink from an ink reservoir to the tip of a pen. The simplest technique is to rely on a gravity feed; however, this will not work well, and may not work at all, if the pen is turned upside down or if the ink is too viscous.
Another technique is to use a pressurised permanent gas, such as nitrogen, within the ink reservoir. The gas ensures that a sufficient pressure is maintained on the ink to push it towards the tip of the pen. However, there is a problem with this technique: as the ink is dispensed from the reservoir, the pressure in the reservoir drops, because there is a greater volume for the gas to occupy. In order to overcome this problem, the gas must be provided initially at high pressure, and must occupy a large part of the volume of the reservoir relative to the ink: in practice, up to 90% of the volume of the reservoir may initially be occupied by gas.
SUMMARY OF THE INVENTION
We have now found that the problems described above can be overcome and that fluids can advantageously be dispensed from a reservoir by using a pressure generating composition capable of releasing a volatile component, wherein the volatile component is released from the composition as the fluid is dispensed in order to maintain the pressure in the reservoir at a level sufficient to aid dispensation of the fluid, the pressure generating composition itself remaining in the reservoir and not being dispensed with the fluid.
According to one aspect of the invention, therefore, there is provided the use of a pressure generating composition capable of releasing a volatile component to generate a pressure, to aid the dispensation of a fluid from a reservoir without the said composition itself being dispensed, wherein the pressure generating composition comprises an oil-in-water or water-in-oil microemulsion, or a siloxane or hydrocarbon grease, or an elastomer, containing said volatile component.
The invention is particularly suitable for dispensing inks from a pen, but can be used for dispensing other fluids from containers thereof.
According to another aspect, the invention provides a dispenser for dispensing a fluid, which dispenser comprises a reservoir containing said fluid, the reservoir having an outlet through which said fluid can be dispensed, and a pressure generating composition capable of releasing a volatile component to generate a pressure within the reservoir to aid dispensation of the fluid, wherein said composition is capable of releasing the volatile component as the fluid is dispensed, in order to maintain the pressure in the reservoir at a level sufficient to aid dispensation of the fluid, and wherein the said composition is not dispensed with the fluid, said pressure generating composition comprising water-in-oil or oil-in-water a microemulsion or a siloxane or hydrocarbon grease, or an elastomer, containing said volatile component.
DETAILED DESCRIPTION OF THE INVENTION
The fluid can be any flowable material, but the invention is particularly suitable for aiding the dispensation of viscous fluids that do not flow well under the influence of gravity. For example, dispensation of pastes such as toothpaste and the like, and gels such as deodorant- or antiperspirant-containing gels and the like, or wet shaving preparations such as soaps and shaving aids, can be assisted by the present invention. The invention is particularly (but not exclusively) useful for aiding the dispensation of fluid from writing or correction instruments, particularly such fluids which are viscous, e.g. inks as used in ballpoint pens and the like. The invention is also useful to aid in the dispensation of solvent and water-based inks.
The pressure necessary to aid dispensation of the fluid from the reservoir depends upon a number of factors, such as the properties of the fluid, and the size and shape of the reservoir. A reservoir pressure above about 0.5 psi (3.4 kPa), preferably above about 1 psi (6.89 kPa), is normally sufficient to aid dispensation of the fluid. The maximum reservoir pressure is dictated by the strength of the reservoir and the characteristics of the pressure generating composition. Generally, the pressure will not be greater than 60 psi (413 kPa), preferably from 1 to 15 psi (6.9 to 103 kPa). In practice, it would not normally be necessary for the maximum reservoir pressure to be above about 10 psi (68.9 kPa). For most dispensers, the reservoir pressure is preferably in the range 1 to 4 psi (6.9 to 27.6 kPa). However, the optimum conditions will depend on all the circumstances and can be determined in any particular case by routine trial and experiment.
It will be understood that generally the pressure generating composition is not itself dispensed with the fluid from the reservoir. Rather, the composition remains in the reservoir as the fluid is dispensed, the composition serving to maintain a gas pressure to aid in dispensing the fluid. Thus, the pressure generating composition is normally used in a way in which it does not intimately mix with the fluid to be dispensed, although it may be in direct contact therewith at an interface.
Ideally, the pressure generating composition should be immiscible with the liquid to be dispensed. For example, if the fluid to be dispensed is organic-based, then the pressure generating material should be aqueous-based; and if the fluid to be dispensed is aqueous-based, then the pressure generating material should be organic-based. Alternatively, a barrier may be provided between the fluid to be dispensed and the pressure generating material, in order to prevent contact therebetween especially when both are organic-based or aqueous-based. For example, in the case of an aqueous-based fluid and an aqueous pressure generating material, an organic-based barrier, such as a grease plug, can be provided between the fluid and the pressure generating material. The use of a barrier can be very important when dispensing low viscosity fluids, in order to prevent the formation of air bubbles.
Over a period of time, it is possible for the fluid being dispensed, or for the barrier, to dissolve some of the volatile component from the atmosphere in the reservoir. This does not normally affect the operation of the invention although preferably the barrier material will be such as not to dissolve the volatile component to any significant extent.
Another way of providing a barrier between the pressure generating composition and the fluid to be dispensed is to confine the composition in an expandable bladder, bag or other flexible container, for example, the container being disposed within the reservoir containing the fluid to be dispensed. As the composition releases the volatile component, the container expands to raise the pressure in the reservoir to aid dispensation of the fluid.
In one preferred embodiment of the invention, the fluid is an ink, and the fluid dispenser is part of a writing implement having a tip for delivering the ink to a surface to be written on, or otherwise marked. In this embodiment, the reservoir and the tip are in fluid communication, whereby ink can be fed from the reservoir to the tip.
In another embodiment, the fluid is an ink, and the fluid dispenser comprises a refill for a writing implement. The ink may be a water-based or solvent-based ink and may be for use in ballpoint pens or other writing instruments.
In further exemplary embodiments, the fluid is a paste such as toothpaste, or a gel material, or a fluid such as a correction fluid or shaving soap or a shaving aid.
In use of the pressure generating compositions in the present invention, the compositions release a volatile component at ambient temperatures. In some embodiments, at least some of the volatile component will be in solution in a component of the composition, or it may be oth
Causton Brian Edward
Gough Dawn Elizabeth Ann
Berol Corporation
Marshall O'Toole Gerstein Murray & Borun
Walczak David J.
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