CORRECTION FLUID AND DISPENSER

Abstract: A dispenser for a low viscosity correction fluid. The dispenser comprises a correction fluid container (10) from which fluid is dispensed through an outlet (7). A member such as a wire (8) is movable within the outlet by manipulation of the pen so as to initiate the dispensing of correction fluid. An inlet is provided for supplying replacement air to the container as fluid is dispensed. The correction fluid comprises a readily evaporable solvent, a resin dissolved in the solvent and capable of forming a flexible film on evaporation of the solvent, a finally divided pigment suspended in the solvent, and a suspending agent which prevents settling out of the pigment.

Description: CORRECTION FLUID AND DISPENSER The present invention relates to a correction fluid and a dispenser for such a fluid. The use of correction fluids is well known by for example typists to obliterate errors in documents and thereby to avoid the need to completely retype documents. Correction fluids must have a high opacity so that none of the obliterated error shows through, should be quick drying, and should be flexible when dry to enable a corrected document to be flexed. These criteria are met by available correction fluids which are in the form of fairly viscous pastes applied by brush. Users of available correction fluids find their application difficult and messy, particularly with a partly used fluid bottle, because a hardened mass of the fluid tends to build up around the neck of * the bottle. Conventional correction fluids include a filler material in the form of china clay and when dried out are difficult to dislodge. It is not possible with known fluids therefore to dispense them other than with a brush. It would not be possible to avoid blockage of a narrow passageway filled with a conventional correction fluid and it would be very difficult indeed to unblock such a passageway. It is an object of the present invention to provide an improved correction fluid dispenser and an improved correction fluid. According to the present invention, there is provided a dispenser for a low viscosity correction fluid, comprising a correction fluid container, an outlet from the container from which fluid is dispensed, a member movable within . the outlet by manipulation of the pen 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 may be in the form of a wire which extends into the. outlet. The wire is connected to a button at the end of the pen remote from the outlet. Depression of the button causes the wire to slide in the outlet, pushing out any correction fluid left therein and thereby initiating the dispensing of fresh fluid. Preferably, the wire extends through a tube coaxial with the pen body so that the fluid is stored in the annular space between the tube and the pen body. The pen outlet is preferably connected to the annular space via a restricted passage, for example a passage partially blocked by a reticulated foam * pad or pads. Alternatively, the restricted passage may be defined between the pen body and a member or member inserted into the pen body. The end of the passage remote from the outlet preferably opens into the annular space at a level above the bottom of the tube through which the wire extends when the pen is positioned with its outlet pointing vertically downwards. An air vent is provided communicating with the tube to enable air to pass down the tube and replace fluid dispensed via the outlet. As an alternative to connecting the wire to a button, the wire could be connected to a weight movable within the pen body so that shaking the pen parallel to its axis would cause the weight and wire to reciprocate relative to the pen body. According to the present invention, there is also provided a low viscosity correction fluid comprising a readily evaporable solvent, a resin dissolved in the solvent and capable of forming a flexible film on evaporation of the solvent, a finely divided pigment suspended in the solvent, and a suspending agent which prevents settling out of the pigment. Preferably the fluid also contains a surfactant to improve flow characteristics and a plasticiser to improve crack resistance. The resin acts as a binder to provide good pigment binding capacity at high pigment loadings with as low a viscosity as possible. It has to be soluble in fast evaporating solvents suitable for the wetting out of paper, and to have high adhesive characteristics to a substrate and to be readily overcoated by itself without loss of adhesion. It also has to be water white and not to yellow or discolour with age. Suitable resins have been found amongst the following: a) Vinyl chloride polymers. b) Acrylic polymers. c) Vinyl chloride/Vinyl ether copolymers. d ) Acrylic/styrene copolymers. Preferably a vinyl chloride/vinyl ether co- polymer with a low viscosity range is used. The plasticiser improves crack and craze resistance of the highly pigment film, improves adhesion of the binder to the pigments, and reduces dusting. Suitable pl'asticisers have been found amongst the following: a) Chlorinated paraffins. b) Low molecular weight esters of isophthalic and phthalic acids. c) Epoxidised fatty acid esters. Preferably an epoxidised fatty acid ester is used to give the required flexibility and adhesion without loss of hardness of the film. The surfactant improves flow characteristics on metal and plastic substrates, and minimises air entrapment during manufacture of the fluid and in the filled pen. Suitable wetting agents have been found amongst the naturally occurring long chain esters or soaps. The pigments provide the required colour and opacity. Suitable pigments have been found to be based on Titanium Dioxide selecting a blue/white grade made by the chloride process. The suspending agent minimises settlement of the pigments which would cause blockage if not 0 controlled. Suitable agents have been found amongst the following: a) Magnesium alumino silicates. b) Hydrogenated castor oils. 5 c) Inorganic platlet fillers. Preferably a platlet filler is used. Suitable solvents have been found amongst the following: a) Low molecular weight alcohols. Q b) Alkyl benzenes. c) Chlorinated hydrocarbons. Preferably an alkyl benzene is used. One example of a suitable formulation for the fluid is given below: 5 % Weight Binder Resin 3.96 Plasticiser 0.10 Surfactant 0.40 Pigments 56.04 Suspending Agents 5.90 Solvent 33.60 100.00 The correction fluid is formulated to have a low viscosity in contrast to the known viscous correction fluids so that it may flow readily out of the dispenser and the solvent is such that it will evaporate within a few seconds (e.g. 1 or 2 seconds) of being applied to a document. Embodiments of dispensers in accordance with the present invention will now be described, by way of example, with reference to the accompanying drawings, in which : Fig. 1 is a sectional view through the outlet end of a first dispenser pen embodying the invention; Fig. 2 is a sectional view through the other end of the pen illustrated in Fig. 1; Fig. 3 illustrates the general structure of a cap for use with the pen of Figs. 1 and 2; Fig. 4 is a sectional view through the outlet end of a second dispenser pen embodying the invention; and Fig. 5 is a sectional view through the other end of the pen illustrated in Fig. 4. Referring to Fig. 1, the drawing illustrates the outlet end of a correction fluid dispenser. The dispenser comprises a tubular main body 1 into which the end of an outlet ' assembly is inserted, the outlet assembly comprising a body 2 within which a lower insert 3 and an upper insert 4 are received. An acrylic foam pad 5 having 60 pores per square inch is loosely retained between the outlet assembly body 2 and the lower insert: 3. The foam pad 5 is reticulate, that is the individual pores of the foam are interconnected so that a fluid can pass through the pad as through a filter. A body of foam 6 is retained within the lower insert 3, the foam body 6 being highly compressed. The foam body may have for example 100 pores per square inch. The outlet assembly body 2 defines an outlet passage 7. A zinc wire 8 extends along the axis of the main body 1, through the foam body 6 and the foam pad 5 and into the passage 7. The zinc wire 8 extends within a polypropylene extruder tube 9 within the main body 1. The zinc wire may have for example an outside diameter of 0.335mm whereas the tube 9 has an internal diameter of for example 1.5mm. The wire is thus able to move very freely within the tube 9 but is prevented from bending to any great extent because of the presence of the tube. An annular space 10 is defined between the main body 1 and the tube 9. Fluid within the annular space 10 can flow to the pen outlet passage 7 along the path indicated by the line 11, that is through a frustoconical passageway 12 defined between • the inserts 3 and 4, along fluid channels 13 defined in the peripheral surface of the insert 3 and extending parallel to the main axis of the pen,, through a restricted passageway 14 defined between an annular formation of triangular cross-section in the insert 3 in a mating groove in the outlet body 2, through the annular passageway 15 defined between the insert 3 and the outlet body 2, through the foam pad 5 and into the main outlet. Referring now to Fig. 2, this drawing illustrates the top end of the dispenser, that is the end remote from the outlet. The main body 1, wire 8, tube 9 and annular space 10 carry the same reference numerals as in Fig. 1 and it will be appreciated that the central portion of the dispenser is simply a continuation of the generally tubular structure illustrated in the top portion of Fig. 1 and the bottom portion of Fig. 2. The top end of the pen comprises a moulded insert 16 which is received in the tubular main body 1 and in turn receives the top end of the tube 9. The annular space 10 is thus sealed at the top end of the dispenser. The wire 8 extends through the insert 16 and is secured to a button 17 which is biased to the position shown by a spring 18. The aperture in the insert 16 through which the wire 8 extends is relatively loose so that air can penetrate the tube 9 from around the button 17. An integrally moulded cap 19 is supported on the insert 16 and can be moved to an open position as illustrated to allow access to the button 17 and to allow communication between the interior of the tube 9 and the atmosphere or alternatively can be pushed down onto the top of the insert 16 so as to effectively isolate the tube 9 from the atmosphere and to prevent depression of the button 17. The dispenser is filled with correction fluid by first securing the insert 16 and tube 9 in the body 1, secondly inverting the body 1 so that the insert 16 is pointing vertically downwards, and thirdly pouring correction fluid into the annular space 10. The outle't assembly 2 is then inserted into the body 1. To use the dispenser, it is inverted so that the outlet assembly is pointing vertically downwards. Correction fluid then travels along the path indicated by arrow 11 to the outlet, the length and restricted cross-section of the path followed by the fluid and the resistance to rapid flow presented by the foam pad 5 ensuring that the rate of flow of the fluid is relatively limited. The fact that the end of the annular space adjacent the insert 16 is sealed means that as fluid is dispensed it can only be replaced by air passing down the tube 9. This means that there must be a differential pressure between the space adjacent the insert 16 and the atmosphere and this is effective to prevent correction fluid flowing along the tube 19 towards the insert 16. The path followed by air entering the space 10 is indicated by arrow 20. The body of foam 6 is sufficiently compressed to prevent any direct leakage of fluid therethrough. After first usage the dispenser can be stored by simply placing the cap 21 illustrated in Fig. 3 on the outlet assembly 2. A tubular formation 22 in the cap engages over the end of the passageway 7 to effectively seal it against the atmosphere. The end of the cap is provided with apertures 23 so that as - the cap is pushed onto the outlet assembly there is no tendency for the cap to pump air into the passageway 7 which would result in fluid being pumped back into the dispenser body. There will however be some drying out of the fluid in the end of* the passageway 7 and when the dispenser is next required fluid will not normally begin to flow through the passageway as soon as the cap 21 is removed as there will be a small quantity of solidified fluid within the passageway 7. To remove this solidified material it is merely necessary to flip open the cap 19 and depress the button 17. This causes the wire 8 to reciprocate in the passageway 7, clearing the solidified material. The pen is then ready for use and can be used in exactly the same manner as an ordinary pen, moving the tip of the outlet assembly across for example a sheet of paper leaving a line of correction fluid on the paper where it has been contacted by the pen. If however it is required to dispense a significant volume of correction fluid to for example obliterate an area of a substrate it is simply necessary to press the button 17 repeatedly. A droplet of correction fluid then develops on the tip of the dispenser and this can be delivered to the required area with ease. It will be noted from Fig. 1 that when the dispenser is positioned vertically with the outlet assembly downwards the bottom end of the tube 9 is located below the passage 12 defined between the inserts 3 and 4. It has been found that this relative orientation is preferable as it avoids dripping of correction fluid from the pen. If the relative orientations of the end of the tube 9 and the insert 12 are reversed there is a tendency for fluid to drip from the outlet 7 even when the button 17 is not being depressed. Fig. 4 illustrates an alternative outlet end to that illustrated in Fig. 1. In the arrangement of Fig. 4, the outlet assembly comprises a body 24 within which a lower insert 25 and an upper insert 26 are received. A washer 27 is arranged adjacent the outlet of the assembly and an axial wire 28 extends through the washer 27 and the outlet. The wire 28 is received within an axial tube 29 which extends to the other end of the pen. A reticulate foam pad having 60 or 80 pores per square inch is sandwiched between the washer 27 and the lower insert 25. A further reticulate foam pad 31 is located upstream of the insert 25. The wire 28 extends through the foam pads 30 and 31. The plastics washer 27 has a sufficiently small hole through it so that as the wire 28 is passed through the foam pad 30 it cannot force any of the foam pad into the outlet of the pen as if this were to happen there would be a tendency for the outlet to be blocked. The internal diameter of the upper insert 26 is typically 9 millimetres and the outside diameter of the tube 29 is typically 2 millimetres. The gap between the tube 29 and insert 26 is sufficiently small so that when the pen is turned upside down . capillary forces prevent fluid from flowing towards the opposite end of the pen. This effectively prevents any fluid within the tube 28 from flowing down the tube 28 when the pen is inverted. Fig. 5 shows an alternative to the end assembly shown in Fig. 2. Referring to Fig. 5, the end assembly comprises a body 32 of flexible plastics material „ having a serrated edge suitable for insertion into the end of a pen. A cap 33 is secured by a flexible bond to the body 32 and can be pushed down to a closed position onto the body 32. Means (not shown) are provided for engaging the cap 33 in the closed position. The wire 28 supports a button 34 and a spring 35 is positioned between the button 34 and a reticulate foam pad 36 received within the body 32. Thus when the cap 33 is moved to the open position the button 34 moves upwards with the wire 28 as a result of the force applied by the spring 35. When a person wishes to use the pen, he first flips open the cap 33 and then pumps the . pen by repeatedly pressing the button 34. This causes the wire 28 to reciprocate in the pen outlet, removing any dried correction fluid therein. Correction fluid can then filter down through the foam pads 31 and 30 to the pen outlet. Replacement air passes down the tube 29 but capillary forces resist any tendency of the correction fluid to escape up the tube 29. The described pens have been described as dispensing correction fluid by which is normally understood a white fluid used for obliterating mistakes in for example typed documents. It will be appreciated of course that any colour of fluid could be dispensed. Furthermore the dispenser could be used as a simple pen rather than solely for the purposes of obliterating matter from paper.

Claims: CLAIMS: 1. A dispenser for a low viscosity correction fluid, comprising a correction fluid container, an outlet from the container from which fluid is dispensed, a member movable within the outlet by manipulation of the pen by the user to initiate dispensing of the correction fluid, and an inlet for supplying air to the container to replace dispensed fluid. 2. A dispenser according to claim 1, wherein the movable member is in the form of a wire which extends into the outlet. 3. A dispenser according to claim 2, wherein the wire is connected to a manually operable button at the end of the pen remote from the outlet. 4. A dispenser according to claim 2, wherein the wire is connected to a weight reciprocable relative to the outlet. 5. A dispenser according to claim 2, 3 or 4, wherein the wire extends through a tube coaxial with the container body so that the fluid is stored in the annular space between the tube and the body, and the tube communicates directly with the inlet for replacement air. 6. A dispenser ' according to any preceding claim, wherein the outlet communicates with the container through a passageway restricted by one or more reticulated foam bodies. 7. A dispenser according to any one of claims 1 to 5, wherein the outlet communicates with the container through restricted passage defined between the container body and one or more further bodies inserted into the container body. 8. A dispenser according to claim 7, wherein the end of the passage remote from the outlet opens into the annular space at a level above the bottom of the tube through which the wire extends when the pen is positioned with its outlet pointing vertically downwards. 9. A low viscosity correction fluid comprising a readily evaporable solvent, a resin dissolved in the solvent and capable of forming a flexible film on evaporation of the solvent, a finely divided pigment suspended in the solvent, and a suspending agent which prevents settling out of the pigment. 10. A low viscosity correction fluid according to claim 9, comprising a surfactant to improve flow characteristics. 11. A low viscosity correction fluid according to claim 9 or 10, comprising a plasticiser to improve crack resistance. 12. A dispenser for a low viscosity correction fluid, substantially as hereinbefore described with reference to the accompanying drawings. 13. A low viscosity correction fluid, substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: BROMLEY DAVID, SHAH MAZHAR, BROMLEY, DAVID, SHAH, MAZHAR
Applicants: SHAH MAZHAR, SHAH, MAZHAR
Application year: 1985
Main classification: B43K29
IPC codes: B05B11, B43K5, B43K8, B43L19