DISPENSER FOR A LIQUID CONTAINING VOLATILE COMPONENT

Abstract: A dispenser for applying correction fluid to documents to be corrected is in the general form of a pen with a nib body (2) at one end having an outlet duct (4) through which the fluid is dispensed. At the opposite end there is a valve operated by a push-button (9) for equalising the pressure inside and outside the container body (1) of the dispenser and attached to the valve is a rodding wire (6) that extends axially through the pen to the outlet. The valve is normally biased to the closed position and when the push-button is depressed the valve opens and at the same time the rodding wire dislodges any fluid that may have solidified in the outlet. The correction fluid used in the dispenser has toluol as its volatile solvent component and major parts of the dispenser are moulded in nylon which is resistant to toluol.

Description: Dispenser for a liquid containing volatile component f. This invention relates to fluid dispensers, in particular for dispensing typewriter correction fluids and like liquids containing a volatile component. Correction fluids used by typists and other office 5 staff to obliterate errors in documents must have a high opacity, should be quick drying and should be flexible when dry. Those criteria are met by available correction fluids which are in the form of fairly viscous liquids applied by brush from a bottle and contain a volatile solvent that 10 evaporates very rapidly. However, the existing use of bottle-and-brush can be messy and wasteful since a mass of solidified material tends to build up around the mouth of the bottle and the stem of the brush and the fluid remaining in the bottle may gradually 15 solidify until it is too hard to use. Also, a brush is a comparatively imprecise means of application. One attempt at least has been made to produce a correction fluid container that is also an applicator which can be used to 'blob' the fluid directly on to the document to be corrected 20 but it was not successful. A particular problem with such an applicator is that the fluid is dispensed through a narrow passageway which tends to become blocked with solidified fluid, after which the applicator cannot effectively be used. PCT Patent Speci ication No. PCT/GB 85/00122 discloses 25 a dispenser for a low viscosity correction fluid comprising a correction fluid container, an outlet from the container through which fluid is dispensed, a member movable within the outlet by manipulation of the dispenser by the user to initiate dispensing of the correction fluid, and an inlet for supplying air to the container to replace dispensed fluid. The movable member is in the form of a wire which extends through a tube into the outlet, and the wire is connected to a button at the end of the dispenser remote from the outlet. Depression of the button causes the wire to slide in the outlet, dislodging any hardened correction fluid left therein and thereby enabling the dispensing of fresh fluid. Air enters the container through the inlet to replace fluid dispensed through the outlet. The inlet is sealed by an air¬ tight cap when the dispenser is not in use. The rate of flow of fluid through the outlet is determined by the dimensions of a restricted passage partially blocked by a reticulated foam pad. It has been found that if a user forgets to replace the the air-tight cap between uses of the dispenser, fluid can dry out. Furthermore, the reticulated foam pad can become clogged, particularly if the fluid viscosity rises as a result of partial drying out. It is therefore an object of the invention to provide an improved fluid dispenser for this duty. According to the present invention, there is provided a dispenser for a fluid containing a volatile component, the dispenser comprising a fluid container, an outlet from the container from which fluid is dispensed, a member movable within the outlet by manipulation by the user to clear the outlet for the dispensing of the fluid, and an inlet for supplying air to the container to replace dispensed fluid, wherein the inlet is sealed by a valve which is biased to a closed position but which may be opened by the user, the valv automatically returning to the closed position when released by the user. Preferably, the valve is connected to the movable member such that opening of the valve automatically clears the dispenser outlet and simultaneously equalises the pressures inside and outside the container. As to the composition of the correction fluid with which the dispenser is to be filled, the correct choice of volatile solvent is particularly important. Both toluol and trichlorethane have the right vapour pressure and evaporate quickly; but toluol is much to be preferred because trichlorethane is hazardous to use in manufacture. Advantageously, toluol is employed in co-operation with a dispenser having plastics components moulded in nylon, since it was found that nylon is resistant to toluol whereas other plastics tested were not. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a diagrammatic longitudinal section through a dispenser embodying the invention, Figures 2 to 6 are longitudinal sections through various components of the dispenser as manufactured, being respectively, the dispenser casing, a nib body at one end, a cap for the nib body, a push-button at the opposite end for actuating a valve member and a rodding wire, and a steel insert lodged in the nib body, and 5. Figure 7 shows the valvemember in external side elevation. Referring to the drawings, the dispenser comprises a tubular casing 1 supporting a nib body 2 at one end and a valve housing 3 at the other end. The nib body 2 is a coaxial extension of the casing 1, being of hollow circular section, jrj and tapers toward an outlet 4. A tubular metal insert 5 is lodged coaxially within the nib body 2 defining a capillary bore of 0.71 mm diameter through which passes a rodding wire 6 of 0.65 mm diameter that extends also within the outlet 4. 15 The valve housing forms a hollow tubular extension on the opposite end of the casing 1 and embodies a coaxial inlet 8 defining an internal valve seat 11. The rodding wire 6 extends along the axis of the tubular casing 1 and is secured at that opposite end to a movable valve member 7 20 mounted coaxially in the valve housing 3 to co-operate with the valve seat 11 and having a stem 7 extending out through the inlet 8. The outer end of the valve stem is secured to a cap 9, forming a push-button, which is biased axially away from the valve housing 3 by a compression spring 10. 25 The valve member 7 and the valve seat 11 have mating frusto - conical surfaces. The correction fluid contents within the casing 1 can be stirred and mixed by shaking the dispenser to agitate a loose annular body 13 disposed within the casing around the wire 6. A cap 14 is provided for placing over the nib body 2 when the pen is not being used. ■When it is intended to use the dispenser, it is first shaken and is then held nib downward and the push¬ button 9 depressed once or several times and released. This causes the wire 6 to protrude through the outlet 4, dislodging any blockage caused by dried fluid. It also opens the valve 7 and thereby ensures that the pressure within the dispenser is equalised to the pressure of the surrounding air. This equalisation of pressure is important. With the cap 14 removed, the dispenser can then be placed with the nib outlet in contact with the document to be corrected and used like an ordinary pen, the correction fluid passing through the clearance between the metal insert tube 5 and the wire 6. As fluid is dispensed, capillary action and surface tension tend to maintain the flow, but the pressure gradually falls within the dispenser until eventually no further fluid can flow. If further use of the dispenser is required the user simply presses the cap 9 again to equalise the pressures. Dripping or blobbing is avoided by the fact that during use the valve 7 is closed. If after use the user forgets to replace the cap 14 the fluid within the outlet solidifies and further loss of the volatile component of the fluid is prevented. When the dispenser is to be used again the blockage in the outlet 4 is simply removed by pressing the button 9. Opening of the valve 7 is kept to a minimum and as a result substantial loss of solvent is avoided. By carefully gauging the clearance between the tubular metal insert 5 and the wire 6 and matching this clearance to the viscosity of the fluid to be dispensed and the desired rate at which the fluid should be dispensed, the "writing" characteristics of the dispenser can be determined. Whereas the showing of the dispenser in Figure 1 is diagramma ic, Figures 2 to 7 show parts of the dispenser as actually manufactured. The casing 1 in Figure 2 is moulded in nylon and has the valve housing 3 formed as an integral part of the casing, the valve seat 11 being carried by a frusto-conical internal diaphragm 16. The nib 2 in Figure 3 is also of nylon, as are the nib cap 14 in Figure 4 and the valve push-button 9 in Figure 5. It can be seen that the nib cap 14 has an internal socket 15 within which the outlet end portion of the nib body 2 is a snug fit. The metal nib insert 5 shown in Figure 6 is of pressed steel, part cylindrical and part frusto-conical in form. The valve member 7 in Figure 7 is of brass and has at the outer end of its stem 17 a head 18 which is a snap fit into a socket 19 in the"push button 9. At its opposite end within the casing 1 the valve member has a socket 20 to receive the end of the rodding wire 6. The annular agitating body 13 within the casing, also of metal, can be fairly long, externally grooved and, if desired, tapered at -one end to readily enter the tapering nib body 2. The composition of the correction fluid used in the dispenser can be as follows:- % Weight Binder Resin 3.96 Plasticiser 0.10 Surfactant 0.40 Pigments 56.04 Suspending Agents 5.90 Solvent 33.60 Suitable binder resins are found amongst vinyl chloride polymers, acrylic polymers, vinyl chloride/vinyl ether copolymers and acrylic/styrene copolymers, with the preferred binder being a vinyl chloride/vinyl ether copolymer having a low viscosity range and available under the Trade Mark 'Laro lex' . Suitable plasticisers are found amongst chlorinated paraffins, low molecular weight esters of isophthalic and phthalic acids, and epoxidised fatty acid esters. An epoxidised fatty acid ester, such as methyl ethyl ketone, is the preferred plasticiser, giving the required flexibility and adhesion without loss of hardness of the film. The surfactant acts as a wetting agent and suitable wetting agents are found amongst the naturally occurring long chain esters or soaps. A suitablepigment can be based on titanium dioxide, selecting a blue/white grade made by the chloride process. Suitable suspending agents are found amongst magnesium alumino silicates, hydrogenated castor oils and inorganic platelet fillers. 5 Preferably, a platelet filler, such as talc, is employed. The choice of the volatile solvent is particularly important. Usable solvents are found amongst low molecular weight alcohols, alkyl benzenes and chlorinated - Lα hydrocarbons. However, an alkyl benzene is preferred, of which toluol is particularly recommended. 15

Claims: CLAIMS 1. A dispenser for a fluid containing a volatile component, comprising a fluid container and an outlet from the container from which fluid is dispensed, a member movable within the outlet by manipulation by the user to clear the outlet for the dispensing of the fluid, and an inlet for supplying air to the container to replace dispensed fluid, wherein the inlet is sealed by a valve which is biased to a closed position but which may be opened by the user, the valve automatically returning to the closed position when released by the user. 2. A dispenser according to Claim 1, wherein the valve is connected to the movable member whereby concurrently with the opening of the valve to equalise the pressures inside and outside the container the dispenser outlet is cleared. 3. A dispenser according to Claim 1 or Claim 2, wherein the container is a generally cylindrical elongated casing, the outlet is provided in a nib body at one end of the casing, the valve is situated at the opposite end of the casing and is operated by a push-button at that end, and the movable member is in the form of a rodding wire extending axially through the casing with one end secured to the valve and the other end disposed in the nib body outlet. 4. A dispenser according to Claim 3, wherein the rodding wire passes through an annular metal insert within the nib body whereby a capillary passage for the fluid is defined within the bore of the insert around the wire. 5. A dispenser according to Claim 3 or Claim 4, wherein an annular agitating body is disposed loosely within the casing surrounding the rodding wire whereby fluid in the casing can be mixed or stirred by shaking the dispenser. 6. A dispenser according to Claim 3 or Claim 4 or Claim 5, wherein a removable cap is provided to fit over the nib body which cap has an internal socket within which the outlet end of the nib body is a snug fit. 1Q . A dispenser according to any one of Claims 3 to 6, filled with a correction fluid containing toluol as a volatile solvent component, and wherein one or more moulded plastics parts of the dispenser in contact with the fluid are made of nylon. 1.5 8. A dispenser according to Claim 7, wherein the components of the correction fluid are substantially as set out in the table herein. 9. A dispenser according to Claim 8, wherein the binder resin in the correction fluid is a vinyl chloride/ 20 vinyl ether copolymer. 10. A dispenser according to Claim 8 or Claim 9, wherein the plasticiser in the correction fluid is methyl ethyl ketone. 2:5

Inventors: SHAH MAZHAR, SHAH, MAZHAR
Applicants: SHAH MAZHAR, SHAH, MAZHAR
Application year: 1986
Main classification: B43K8
IPC codes: B43K8, B43L19, C09D10