CA2136084C - Correction fluid - Google Patents

Abstract

An aqueous, correction fluid that includes a suspending agent, a binding resin, water, and an opacifying pigment. The suspending agent is preferably a gum or hydrocolloid, e.g. xanthan gum, and the composition preferably has a shear-thinning index (n) of from about 0.08 to 0.50. The fluid may be dispensed from a pen as d escribed in the figure or from a container. A dispenser (10) comprises elongated body member (12) and barrel (14). A tubular p assage (16) extends through barrel (14) and opens rearwardly into body member (12) for flow of correction fluid from the body memb er into barrel (14). Within tubular passage (16) a tubular spring retainer (26) is disposed in interfitting engagement with barre l (14).

Description

21~6~

ro~ ON F~ID
This inv ntion relat-~ to co,~tion fluids CG~ tion fluids are u~-d for correcting handwritt~n, typ~writt n or photocopisd mar~ings on pap-r ~on-rally, co action fluids ar~ applisd to a pap-r surface in liquid form Aft~r application, th- fluids dry relativ-ly quickly to provld- a film which can off~ctiv-ly cov-r ~rroneo~R mar~ings on the surface and can rscsive a CG J~t-d mar~ing It i~ d-~ir-d that th- dri~d film be ~trongly bond-d to th- pap-r ~urfacs, and ~uffici ntly fl xibls that the film will not b- removed undsr normal conditions It i~ also d-sir-d that the composition dry at a rapid rat~ Oth-r d-sir~d p-rform~nce charact~ri~tic~ include good storags ~tability, and flow and visco~ity charact-ri~tic~ which p-rmit ~a~y and ~v-n aFrl~r-tion of th~ fluid CG..cction fluid~ typically contain a b~ ng r-~in that provides th- flexible film, and an opacifying pigment, u~ually titanium dioxide, di~p-r~-d in a ~olv~nt It i~
d-~irable, for nvironm ntal r-a~ons, that ~o,,~tion fluids includ- littl- or no volatile organic ~olvent~

W O 93/23485 PC~r/US93/02494 ~,~36~ 2 -Correction fluids are often suppliod in a small bottle with an applicator brush attac~o~ to the cap. Since the opacifying pigment in the fluid (typically titanium dioxide) tends to settle out o~er time, glass or metal mixing beads are sometimes included to help redisperso the agent, the user being instructed to sha~e the bottle prior to use.
~o.r--ve., thorough ~h~; ng is commonly rogarded ae a nuisance, 80 that much of the opacifying pigment romains at the bottom of tho bottle.
This condition is oxacerbatod by _v~o,~tion of the solvont camponont when the bottlo is opon.
Accordingly, much of the co--oction fluid in each bottle may bo thrown away as tho solids bocomo increasingly difficult to rodisperso.
In go~eral, th- invontio~ foaturos, in one aspect, an agu-ous correction fluid having a sh-ar- th ~ nn; ng index of botwoon 0.08 and O.S0.
The corroction fluid includos a b~n~ing rosin, an opacifying pigment, o.g., titanium d$oxido, water, a~d a sufficient quantity of a suspon~;ng agent to provido the fluid with tho above shear-th i nn ~ n~ indox.
The invontion features, in another aspect, a correction fluid dispensing system that includos a co~t-;nor and a co~ tion fluid. Th- con~n~r includ-s a chamber for ~ol~ng tho co..oction fluid, and a capping oloment that fits ovor a~ op~ing in tho chamber wall. Tho c~p~ng elemo~t includos a brush element that oxte~ds into tho chamber when the capping oloment covc,~ the oponing. Tho CG~O ction fluid includes water, an opacifying pigmo~t, a susp-nd~g agont, and a bi nA ~ ng resin.
Tho invontion foaturo~, in anothor 2136~8~

aspeet, an aqueous correction fluid, w_ieh includes a bin~;n~ re~in, at least 15% of an opacifying pigment, water, and a 8U8r -n~i ng agent The invention features, in another aspect, a correction fluid dispensing system ineluding a pon ha~ing a chamber for _olding a correction fluid, the chamber being dofined by a wall including an opening, and a spring loadod valvo at said opening for controlling flow of t_e fluid t_rough tho oponing Th- di~ponsing system ineludss a corroction fluid within the chamber The correctlon fluid contalns a bin~ing rosin, an opac~fying plgmout, a susp~Aing agont, and wator Tho invention f-aturos, in another asp-et, a proeoss for covoring a mar~ing on a papor Tho m thod inelud-s contaeting an applieator with a eorr-etion fluid having a shear-~h~nning index of botwoon 0 08 and 0 50 The applicator may b- any sultabls applleator for uso wlth fluid c ~po-~tions, o g , a brush or a pQn tlp The fluld eontain~ a bin~ng realn, an opaclfylng pigmont, a ~u-p-n~ng ago~t, and wator Th- contacting i~ done with suffieiont foree that ~o~ of th- g-llod cGl.e:tion fluid flo~ onto tho applieator The eo ~:tion fluid on th- application 1~ us-d to eover a mar~$ng on a pap-r surfaeo, and th-cGl c tion fluid is th-~ allow d to dry A
eorroeti~e mar~ing m y ~ub-~guontly b~ appliod to tho dri-d corroctlon flu$d, lf d ~ir-d Tho correetion fluids of tho invention i~elude a 8U8pOnA ~ ng ag-nt to provid- shoar ~h~nn~n~ fluid8, i o , fluids whieh ~xhiblt ~on-now~o~n ~ ~rtios ~y thls, it is moant that th- flulds aro r-lativ-ly th$c~ at r-~t, and do Y

W093/2~8~ 2 i 3 6 0 8 ~ PCT/US93/0249~

not readily flow out of a container if .he container i~ inverted. Yet the fluids ~hin out when sheared, and are thus easily applied to a surface because they flow readily onto a~
applicator, e.g., a brush, when the applicator actively contacts the fluids. The fluids also flow readily from the applicator to a surface when the applicator is passed across the surface.
Significantly, because of the non- =
newtonian properties of the fluids, the opacifying pigment in the ~elled correction fluids does not significantly settle over ~xtended periods of time, eliminating o-reducing the need to sha~e the fluid co~tainer.
Advantageously, the thixotropic flow properties allow the fluids of the invention to be dispensed using a wlde variety of dispe~sers.
In particular, due to the non-settling nature and resistance to viscosity change with change in temperature of the fluid, the fluid can be dispensed from a pen dispenser without "gushing"
or other problems usually encountered. Further, the fluid does not normally require sha~ing beforo usq, and can be used over long periods of time without settling or drying out. In addition to the ad~antageous flow properties, the com~ositions have good drying, bonding, floxibility and storage stabllity characteristics.
The non-n~wtonian properties of the gel may be maasured in terms of tho shear-th~nning index ~n), as described, e.g., in Zgambo, ~.S. Patent No. 4,786,198 (rZga~bo~)-For the purposes of thi6 invention, the shear-thinning index (~} i8 W093/2~8~ 2 1 3 6 0 8 ~ PCT/US93/0249~

calculated by fitting shear stress (T) and shear rate values (y) obtained from rheological measurements on a viscometer, e.g., a ~AARE
ROTOVISCO* ~aake Inc., Saddle Brook, N.J., to the empirical power equation T=R ~ (whsre R and n are calculated constants). As described in Zgambo, the shear-th~nn~ng index is obtained by mQasurements of an aqueous solution of the shear-thinning material at sheAr rates between about 30 and about 300 sec~1. Shear stress values are measured from the curve on the viscometer at different shear rates (typically 30, 90, 150, 210 and 300 sec~1) and the measured shear stress values are fitted to the shear lS rates using a curve-fitting program.
By ~aqueous" it is meant that the fluid is water-based, and contains less than about 10% of volatile organic solvents.
Preferred compositions include, as the suspending agent, a gum or hydrocolloid, preferably a semi-synthetic gum, e.g. a cellulose derivative or ~icrobial fermentation gum, more preferably xanthan gum, a titanium dioxide pisment, an acrylic polymer binder resin, and a phosphate ester dispersa~t.
Preferably, the composition includes, by weight, about 2 to 20 percent bindi~g ro~in; at least 15 percent pigme~t; about 0.2 to 2.0 percent dispersa~t; and about 0.15 to O.6 percent suspending agent. They also include water. The drying time of preferred compositions is less than about 60 seconds; the viscosity at 40~C. i8 within + 10~, preferably + 5~, of the viscosity at 25~C.; and the shear th1nntng index (n) from 0.15 to 0.30. Preferred compositions ~avs a settling value of about 10, when measured according to AS~ D865-48 (1974).
~,- *trade~ark W093/2348~ PCT/US93/02494 2 ~3 6 Other features and advantages of the invention will be apparent from the description of the preferred embodiment thereof, and from the cla;mR
5The figure i8 of a preferred correction fluid disponsing systom The preforred correction fluid includes a su~ ng agsnt, a b;n~;ng resin, a disporRing agent, an opacifying pigmont, and water T_e flow and s-ttling characteristics of th- fluid are provid-d by tho ~usp~n~ng ag nt Th- 8U8pOn~ i n~ agent i~ dispc~ in tho composition to provide a correction fluid having a Rh-ar-thtnn~ng indox (n) of betw en about 0 08 to about 0 50, ~ r- pr-f-rably b-tw n about 0 10 and 0 30, and ~ st pr-forably b-twoon about 0 15 to about 0 25 Too low a ~h-ar-~h~nn~ng index may r-~ult in a fluid that doe~ not have suffici nt flow to bo ~asily appli-d; too high a shear-th~nn~ng indox may result in a fluid that gushos or that oxhibits settling of tho pigment Inclu~ion of the gu~p~nA~ n~ ag nt8 provid-~ corr-ction fluid~ which ar- thir~~n~
vi~cou~ liguid~ at r-st or low ~h-ar rat-s For oxamplo, co_positions of tho invontion pr-f-rably havo a viscosity of b-tw n 400 and 2000 cP~, moro prof-rably b-tw en about 500 and 1000 cPs, at a ~h-ar rato of 30 s-c~1 ~ol_vc,, in r-spons- to tho high sh-ar rat-s n~o~nterod during application of tho compo~ition, ~ g , by br~h~ng, th- compo~itions und-rgo sh-ar-~h~nn~ng and have an estimated vi~cosity of le~s than about 5 cPs (obt~n~ by xtrapolation from th~ log cur~-s of shear rate and sh-ar ~tre~s) Th- pr-f-rred fluid~ al~o do not und-rgo a ~ignificant chang- in vi~co~ity in W093t2~8~ 2 1 3 6 G 8 4 PCT/US93/02491 response to temperature. Particularly preferred fluids are those in which the visco6ity at 40~C.
is within + 10%, preferably + 5%, of the viscosity at 25~C.
The preferred suspending agents are gums or hydrocolloids. The gums or hydrocolloids may be natural gums such ~8 plant exudates, e.g., tragacanth, seaweed extracts, e.g., carrageenan, and-alginates. The gums can also be semi-synthetic gums such as cellulose derivati~es, e.g., carboxymethylcellulo~e, guar and locust bean gum, and hydroxyethylcollulose, or microbial fermentation gums, e.g., as xanthan gum. Xanthan gum is a particularly preferred suspending agent. Preferred grades of xanthan gum are available under the trade~arks RELZAN M, RELZAN S, and RELTROL, commercially available from The ~elco Company. RELZAN S and R~LTROL
are easier to disperse, requiring less agitation than KELZAN M.
The amount of suspending agent included in the composition can vary, depending on the flow properties desired and the other components selected. It is preferred that a sufficient quantity of the suspending agent be included to provide a viscosity of from about 500 to lOOO cPs at a shear rate of 30 sec~l, and a ~iscosity of from about 60 to 130 cPs at a shear rate of 300 sec~l. Typically, the correction fluids contain, by weight, about 0.15 to 0.6 perc~nt of the suspending agent, preferably about 0.20 to 0.50 percent.
The binding resin may be any polymeric or monomeric resin which is capable of binding the pigment component to provide, after drying of the correction fluid, a dry, co~lesced residue which i8 substantially water insoluble.
~. A
.

W093/2~85 2 1 3 6 0 8 4 PCT/US93/02491 It i~ further desirable that the residue be receptive to ink, e.g. to markings rewritten over the corrected ~r~.
Many conventional binding resins that can be usQd in the fluids are well-~nown to those skilled in the art. The preferred resins are acrylic polymers, in particular acrylic thermoset polymeric materials, sold in the form of emulsions under the trademarks CARBOSET and CARBOPOL by B.F. Goodrlch. These preferred polymers have acid numbers below about 50, weight average molecular weights betwoen about 15,000 and about 200,000, and glass transition temperatures between about 20~C. a~d about 70~C.
Particul~rly preferred polymers have acid numbers between about 25 and 30, ~ l~cular weights between about 25,000 and 35,000, and glass transition t~peratures between about 25~C. and 60~C. The emulsions normally have a solids level of about 35 to 60%.
~ nough resln should be included in the fluid 80 that a conslstant connective film will result, but not 80 much that the fluid will destabilize with time ~nd thlcken. The preferred co~position contaln about 2 to 20 weight percent binding re~ln, more preferably about 5 to 15 percent, ~nd most preferably 8 to 12 perc~nt.
In order to ~n~ure that a stable composition is formed, ~.e., to avoid flocculation, and to improve distribution of the pigment through the cc~po~ltlon, a dispersing agent is employed. Su~table dispersing agents are those which are co~patible with typewritten ink. Preferred dispar~lng agents are polysorbitans, phosphata qsters, sodium al~yl polyether sulfonates, ethoxylated alcohol, nonyl , . .

W093/2~8~ 2 1 3 6 0 8 4 PCT/US93/02491 phenoxy polyethylene oxide, and octyl phenoxy POE. Of these, organic phosphate esters are particularly preferred, e.g., those commercially available from G~F under the trademark GAFAC RD-510 and BG-510. It i~ preferred that the composition contain from about 0.2 to 2 weight perce~t dispersant, ~ re preferably from O.5 to 1.5 percent, and most preferably from 0.5 to 1.0 percent.
A~y suitable opacifying pignent having adequate hiding power to cover a desired type of mar~ing, e.g., typed or handwritten, on a paper surface, may be utilized in the compositions of the inve~tion. Titanium dioxide is pseferred, as it provides a basic white color whlch can be toned to meet a variety of requirements depe~ding on the paper stoc~ with which the correction fluid is to be ~mrloyed. ~he grade of titanium dioxide i8 selected based upon the binding resin used, and tho de~ired texture of the composition. For most applicatio~, preferred grades of titanium dioxide are R-931, R-900 and R-901, available from B.I. ~upont de Nomours & Co., Wilm~ngton, Delaware, And R~L, available from Tioxide, Quebec, Canada. Of these, R-931 is particularly preferrec. It i8 proferred that the composition contai-, by woight, at loast 15 percent pigm~nt, preferably about 20 to 60 perc~nt, ~ re preferably about 25 to 50 porcent, and ~ st preferably about 35 to 45 percent.
The amount of water in the -luid will depend upon the amount required to hycrate a give~ suspending agent and disper~e t~e selected pigment. Normally, a w~ter level of _rom about 35 to 65 weight percent, ba~ed on the total weight of the compo~ition, will ba su table.

21360~ ~ -The amount of water roquired to hydrate the Xanthan gum i8 normally between 33 and 50 weight percent of the total amount of water in the eompo~ition. The pigment dispersion contain~
the remaining 50 to 67 weight pereent of the total amount of water in the eompoRition.
The eompositions of the in~ention ean inelude other eonventional ingredient~. For example, ehelating agents, such a8 sodium EDTA, are normally included in the fluld in amounts between 0.1 and 1.0 pereent by woight to protoet any metal parts in tho disponser -ga~n~t motal ions prosent in the wator. DQfoamors are alco normally ineluded.
Proferred eompositions ~hlb~t relat~vely short drying timos (proforably less than 60 sseo~A~). Compositions ean bo test-d for drying time by applying the fluid on tho marking to bo eollceted and at 5 ~oeond intorval~ determining tho timo wh~n you can write over or type o~or tho fluid without di~turbing the surfaeo of the CG~J :t-d mar~.
Preferrod eompositions also ~xhibit vory little sottling o~er timo. When settling is moasurod aeeording to ASTM D2243-68, a ~no ehang~ or a slight~ rating is typically obt~ n~A . When moa~ured by the moro quantitativ- sottling m asuromont method outl~ n ~A in ASTM D869-48 (1974), tho eompositions normally are ratod about 8 to 10 on a seale of 1 to 10, whoro 10 i~
perfoet susponsion.
The fluid i~ prof~rably mado in thro~ -stag~.
~rst, tho hydroeolloid is 810wly add-d into a~.G~imatoly ono thlrd of tho total amount of wator to bo u~-d in the eomposition.
This allows the h~d~o olloid to bo hydratod.

W093/23485 ~ 4 PCT/US93/Ot494 Mixing is done at a very low shear, 80 as not to incorporate air into the mixture. The speed ia monitored and increa~ed, producing a small vortex as the hydrocolloid dispers$on thic~ens.
Next, a pigment disporsion is propared. The pigment is added into a solution of dispersant in water at a slow rate, to y,~v_~t agglomeration, and mixed at high shear until the pigmont particle size is above 7 on a ~ogman gage. High shear is required to brea~
down the pigment particle size. A high spoed di~persator from Ro~s and 80n~ may bo u~ed to prepare the pigment di~persion. Othor oquipment such as a sand mill, ball mill, Eigor Mill or Gaulin can bo used to obtain th- doslred pigment particle sizo.
Last, tho pigmont disp-rsion is added slowly into tho hydrocolloid solution using a low shear mixer. A small vortox is maint~ne~
during thi~ step. Once all of the pigment dispersion is addod, tho ro~in is added slowly.
Additional colorant may ~o added to tint the fluld to the dosirQd color.
The following ~xamplo illustratos the invention.
Exa~ le Three corroction fluid composltions (~ample~ 1-3) w re propar-d according to tho invontion, wlth formulations as shown in Table 1. ThesQ fluids wore tostod -g~in~t two commercially ava~lable CG~ action fluids, availablo from Glllotto undor the trad-names J~ST FOR GOr~ (control 1) and MISTAR~ O~T~
(control 2). Each fluid was tested for shear-~h~n~n~ ind~x (n), using a ~AAR~ KGlOv~SCOviscomoter at O to 300 sec~1 ~hoar ratos, and tomperature stability using the same procodure W O 93/23485 P(~r/US93/02494 2 ~ ~ 6 ~ 8 ~ - 12 -at 25~ and 40~C The fluids were also tested for opacity, drying time, and flexibility and adhesion Opacity was measured by preparing draw downs of the fluids with a 0 001" Bird Bar on Leneta No 18A charts The charts have a blac~
and white surface which the fluid covers A
contrast ratio measurement was made with a colorimeter and the ratio of tho blac~ ng to the white surface rea~; ng was calculatod to obtain the r-sult Flexibility and adhosion i~ m asured by a fold test The fluid is applied to a mar~ing on a paper substrate and allowed to dry The paper i8 then folded inwardly and creased, and folded croJswi~e and ereased again The dried eo..cction fluid is then sxamin-d for cr~;ng (indieating poor flexibility) or fl~ng off (indicating poor adhe~ion) Results are expressed on a seale of 1 to 5, with S
indicating no crar~ng or fl~ng The r-sults of this testing are shown in Table 2 Th- fluids ~xhibit very little change in th-ir viseosity, on tho av-rage le88 than 5%, ov-r the temperature change which would typ$cally b- ncountered if a fluid in a di~pons-r at room temperature (25~C ) wer-~ub~-ct-d to the heat of the hand of a us-r holding the dispenser (40~C ) The fluids also exhibit significantly lower sh-ar th~nn~ng ind$e-s (about O 20 average) eompar-d to tho control fluids (greater than 0 60), indicatlng that the fluids will resist s-ttling, but w$11 shear thin during use to an advantageously low vioeosity Th~ oth~r properti~s of th- fluid~
are s~milar to tho~e of the control fluids WO 93/2348~ 2 1 3 6 ~ ~ 4 PCI /US93/0249~

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W093/2~85 2 1 3 6 0 8 ~ PCT/IISg3/0249~

The preferred correction flu ds can be applied using conventional bottle and b-ush dispenser6, rolling ball systems, or a squeeze bottle or pen. Advantageously, the flow properties of the fluids of the invention prevent gushing of the fluid when applied from a pen dispenser, a common problem with conventional fluids. Preferably, a squeeze bottle or pen is used, and a spring loaded valve will be provided to control rate of dispensing.
A preferred spring loaded pen dispenser is shown in Fig. 1 and disclosed in U.S. Patent No.
5,056,949.
When ~ pen dispenser is used, it is preferred that the viscosity of the fluid be from about 400 to 600 cPs measured at 30 sec~1.
Referring to Fig. 1, dispenser 10 comprises elongated body member 12 and barrel 14. A tubular passage 16 extQnds through barrel 14 and opens rearwardly into body m~mher 12 for flow of correction fluid from the body m~mher into barrel 14. Tubular passage 16 has a pair of circumferential shoulders 18 and 20 ad~acent the forward end thereof, and is tapered inwardly terminating at a circular rim 22 surrounding and forming an orifice 24. Within tubular passage 16, a tubular spring retainer 26 is disposed in interf itting engag~ment with barrel 1~, tubular spring retainer 26 having an external surface providing for a force fit into tubular passage 16 such that forward surface 28 of the retainer has an outward portion contacting circumferential shoulder 18 and a port_on extending radially inwarding into passage 16.
Retainer 26 has an inwardly projecting portion 30 which serves to support a spring 3~, the W093/2348~ PCT/US93/02494 2,~ 36~ 4 ~-spring being of a diameter to closely fit within the inner wall of tubular spring retainer 26. A
~oeket member 34 having a plurality of axial ribs 36 iQ supported by spring 32 at its forward end and a spherical ball 38 is disposed between soeket member 34 and circular rim 22 of passage 16. Spherical ball 38 is of larger diamoter than the circular rim such that only a portion of the ball extends 1 yo~d orifice 24 with the outer surface of the ball forming a soal when contacting eircular rim 22.
An altornati~e CG. ~ _ ~ tlon fluid dispersing system includos a eont~n~r for storing one of tho proforrod eorroetion fluids.
Tho eont~n~r ineludes a ehambor, whleh i8 deflned by a eyllndrieal wall. A eap flts over an openlng in tho wall. The eap ineludos a brush portion that extonds into tho ehambor. In U80, as the brush is ~ ved through tho eorroetion fluid, the fluid that eontaet~ th-brush is exposed to rolati~oly high shoar and flows onto the brush. The fluid on tho brush agaln thlek n~, and romalns thle~ns~ untll brushod aeross a marking on papor. The shoar foreo of tho fluld eontaetlng tho papor eausos tho fluid to shoar thin and flow onto the paper, e~ ing th- marking. Oneo dry, a corroctive mar~ing ean b- appliod.
Othor embodiments are wlthln tho elaims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An aqueous correction fluid having a shear-thinning index of between 0.08 and 0.50, said correction fluid comprising a binding resin, an opacifying pigment, water, and a sufficient quantity of a suspending agent to provide said fluid with said shear-thinning index, said correction fluid being capable of obscuring an underlying marking when applied over said marking on a paper substrate and of providing a surface, when dry, capable of receiving a corrective ink marking that can be easily read.

2. A composition of claim 1, wherein the suspending agent is a gum or hydrocolloid.

3. A composition of claim 2, wherein the suspending agent is a semi-synthetic gum.

4. A composition of claim 3, wherein the semi-synthetic gum is a cellulose derivative or microbial fermentation gum.

5. A composition of claim 4, wherein the semi-synthetic gum is xanthan gum.

6. A composition of claim 1, wherein the binding resin is an acrylic polymer.

7. A composition of claim 1, wherein the pigment is titanium dioxide.

8. A composition of claim 1, further comprising a dispersing agent.

9. A composition of claim 8, wherein the dispersing agent is a phosphate ester.

10. A composition of claim 1, comprising by weight about 2 to 20 percent binding resin, about 20 to 60 percent pigment, about 35 to 65 percent water and about 0.1 to 0.6 percent suspending agent.

11. A composition of claim 10, further comprising about 0.2 to 2.0 percent by weight dispersing agent.

12. A composition of claim 1, having a settling value of about 10.

13. A composition of claim 1, having a drying time less than about 60 seconds.

14. A composition of claim 1, having a viscosity at 40°C.
which is within ~ 10% of its viscosity at 25°C.

15. A composition of claim 1, having a shear-thinning index (n) of from about 0.10 to 0.30.

16. A correction fluid dispensing system, comprising a container comprising a chamber for holding a correction fluid, said chamber being defined by a wall including an opening, and a capping element covering said opening, said capping element comprising a brush element extending into said chamber when said capping element covers said opening;
and a correction fluid within said chamber, said correction fluid comprising a binding resin, an opacifying pigment, a sufficient quantity of a suspending agent to provide said fluid with a shear-thinning index of between 0.08 and 0.50, and water.

17. A dispensing system of claim 16, wherein the suspending agent is a gum or hydrocolloid.

18. A dispensing system of claim 17, wherein the suspending agent is a semi-synthetic gum.

19. A dispensing system of claim 18, wherein the semi-synthetic gum is a cellulose derivative or microbial fermentation gum.

20. A dispensing system of claim 19, wherein the semi-synthetic gum is xanthan gum.

21. A dispensing system of claim 16, wherein the opacifying pigment is titanium dioxide.

22. A dispensing system of claim 16, wherein said correction fluid further comprises a dispensing agent.

23. A dispensing system of claim 16, wherein said correction fluid comprises about 2 to 20 percent by weight binding resin, about 20 to 60 percent by weight pigment, about 35 to 65 percent by weight water and about 0.1 to 0.6 percent by weight suspending agent.

24. A dispensing system of claim 16, wherein said correction fluid has a settling value of about 10.

25. A dispensing system of claim 16, wherein said correction fluid has a drying time loss than about 60 seconds.

26. A dispensing system of claim 16, wherein said correction fluid has a viscosity at 40°C. which is within ~10% of its viscosity at 25°C.

27. A dispensing system of claim 16, wherein said correction fluid has a shear thinning index (n) of from about 0.10 to 0.30.

28. An aqueous correction fluid capable of obscuring an underlying marking when applied over said marking on a paper substrate and of providing a surface, when dry, capable of receiving a corrective ink marking that can be easily read comprising a binding resin, at least 15% by weight of titanium dioxide as an opacifying agent, a sufficient quantity of a suspending agent to provide said fluid with a shear-thinning index of between 0.08 and 0.50, and water, said correction fluid having a drying time of about 60 seconds or less.

29. A correction fluid dispensing system comprising: a pen having a chamber for holding a correction fluid, said chamber being defined by a wall including an opening, and a spring loaded valve at said opening for controlling flow of said fluid through said opening; and a correction fluid within said chamber, said correction fluid comprising a binding resin, an opacifying pigment, a sufficient quantity of a suspending agent to provide said fluid with a shear-thinning index of between 0.08 and 0.50, and water, said correction fluid having a drying time of about 60 seconds or less.

30. A dispensing system of claim 29, wherein the suspending agent is a semi-synthetic gum.

31. A dispensing system of claim 30, wherein the semi-synthetic gum is a cellulose derivative or microbial fermentation gum.

33. A process for covering a marking on a paper comprising the steps of covering a marking on a paper surface with a gelled correction fluid comprising a binding resin, an opacifying pigment, a suspending agent and water, said correction fluid having a shear-thinning index of between 0.08 and 0.50, said correction fluid being capable of obscuring an underlying marking on a paper substrate and of providing a surface capable of receiving a corrective ink marking that can be easily read, and allowing said correction fluid covering said marking to dry.

34. A process of claim 33 further comprising the step of applying a corrective marking to the surface of the dried correction fluid.

35. A process of claim 33 wherein the suspending agent is a semi-synthetic gum.

36. A process of claim 33 wherein the opacifying agent is titanium dioxide.

37. A process of claim 33 wherein the correction fluid has a drying time of less than about 60 seconds.

38. A process of claim 33 wherein the marking is covered by applying the correction fluid to the paper substrate from a pen applicator.

39. A process of claim 33 wherein the marking is covered by applying the correction fluid to the paper substrate from a bottle and brush applicator.