Note: Descriptions are shown in the official language in which they were submitted.
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T~K li~RZ~nIcATOR ~Y~ lL I
This invention relates to ink eradicator
syatems.
Ink eradicator systems generally include two
components. One component is an aqueous ink that
includes a dye -- typically a triaryl methane -- that
can be converted to a colorless form when contacted
with a substance such as a sulfite reducing agent or a
basic nitrogen compound. The second component is an
aqueous eradicator fluid that includes a substance that
can cau~e the dye to convert to a colorless $orm. A
u~er writes with the ink and, if correction is
necessary, applies the eradicator fluid to the ink
marking to decolorize the dye.
It is desirable to be able to write-over the
area to which an eradicator fluid is applied. One
problem that may occur when write-over of an eradicated
mark is attempted is that the new mark may fade over
time as the dye in the ink comes into contact with the
excess eradicating substance (e.g., sulfite or amine)
in the hardened eradicator fluid.
The invention concerns the combination of an
eradicatable ink a~ueous ink and an aqueous eradicator
fluid. The ink contains a dye that decolorizes if
contacted with a basic nitrogen compound, such as an
amine. The eradicator fluid contains the basic
nitrogen compound. Importantly, the ink also includes
a basic nitrogen compound b; n~; n~ agent that can bind
the excess basic nitrogen compound in the eradicator
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fluid. As a result, when the ink i8 u~ed to overwrite
an area to which the eradicator fluid has been applied,
the r~m~;n;ng basic nitrogen compound in the eradicator
fluid becomes bound to the nitrogen compound b; n~; ng
agent in the ink, and accordingly does not cause
significant decolorization o~ the dye. The ink mark
made over the eradicated area thus has a reduced
t~n~ncy to fade over time.
The preferred dyes are triaryl meth~ne~. The
preferred basic nitrogen compounds are non-volatile,
non-toxic ~m;ne8 like sodium glycinate. The preferred
b;n~;ng agents are metal salts. Magnesium salts like
magnesium sulfate and zinc salts like zinc sulfate are
examples of preferred b; n~; n~ agents.
Preferred eradicator fluids also include a
film-forming polymer. The film-~orming polymer
provides a thin film on the eradicated area, and as a
result may decrease the write-over time. It also may
slow the diffusion of the eradicator fluid to the
paper, and may improve write-over ~uality. Pre~erred
film-forming polymers include polyacrylic acid sodium
salts.
Preferred eradicator fluids have an
eradication time of less than about 3 seconds, and more
preferably less than 2 seconds. Preferred eradicator
fluids have a write-over time of less than about 15
seconds and more preferably less than 10 seconds.
The invention also features an eradicatible
ink including a dye that decolorizes when the ink is
contacted with an 8% weight in water sodium glycinate
solution, and a metal salt capable o~ complexing with
sodium glycinate.
The invention also features a method of
eradicating an ink marking on a substrate. The method
include~ two steps. First, an ink cont~;n;ng a dye
that decolorizes if contacted with a basic nitrogen
compound, a b;n~;ng agent capable o~ b;n~;ng the basic
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nitrogen compound, and water is applied to the
substrate to provide a marking. Second, an eradicator
fluid including the basic nitrogen compound and water
is applied to the marking. The basic nitrogen compound
causes the dye to decolorize.
The invention also features another method of
providing a marking. This method also includes two
steps. First, an eradicator fluid cont~;n;ng a basic
nitrogen compound and water is applied to a substrate
to provide an eradicator fluid coating. Second, an ink
cont;~;n;ng a dye that decolorizes if contacted with the
basic nitrogen compound, a ~;n~;ng agent capable o~
b;n~;ng to the basic nitrogen compound, and water, is
applied to the eradicator fluid coating. Preferably,
the method also includes initially making a mark on the
substrate, over which the eradicator fluid is applied,
with the same ink.
"Eradication system", as used herein, means
that an ink and an eradicator fluid combination are
stored lln~;~e~ in the same general packaging. For
example, the ink can be in one con~;ne~ and the
eradicator fluid in a second cont~;ne~, but the two
containers are included in the same package.
Other ~eatures and advantages of the
in~ention will be apparent from the description of the
preferred ~hodiments thereof, and from the claims.
Preferred com~inations include an ink and an
eradicator fluid. The ink contains a triaryl methane
dye, a metal salt capable of b;n~;ng to the amine used
in the eradicator fluid, an organic acid, a
polyacrylate ~ilm-forming polymer, and water. The
eradicator fluid includes a non-volatile amine capable
of decolorizing the triaryl methane dye, a film-forming
polymer, and water. The ink and the eradicator fluid
also may include a surfactant to ad~ust surface
tension.
Triaryl methane dye~ that are capable o~
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decolorizing in the presence of an amine are known to
those skilled in the art. Examples include Acid Blue
93 and Acid Blue 22. Enough dye should be included in
the ink to provide the desired color inten~ityr but not
ao much that large quantities of eradicator fluid must
be applied to a mark made with the ink to cause it to
decolorize. Preferred inks include between 2% and 5%,
and more preferably approximately 4%, of the triaryl
methane dye by weight.
1~ The preferred metal salts are capable of
b; nA; ng to the amine u~ed in the eradicator fluid. The
metal salt preferably also i8 soluble in the ink.
Examples of ~alts are magnesium sulfate and zinc
8ul fate.
The ink should include a quantity of metal
salt sufficient to bind to excess amine when the ink i8
applied to an eradicator fluid layer made over an ink
mark. But not 80 much metal salt should be included
that excessive quantities of eradicator fluid must be
applied to eradicate the ink mark being corrected. The
ink mark to be corrected may include the metal salt,
and enough amine mu~t be in the eradicator fluid both
to bind with the metal salt in the ink mark and to
decolorize the dye. Preferred inks include between 5%
and 15%, and more preferably between 8% and 12%, of the
metal salt by weight.
The organic acid increase~ the acidity of the
ink and as a result increases the color intensity of
the triaryl methane dye. Examples of organic acids
include ci~ric acid, and tartaric acid. A sufficient
~uantity of the organic acid should be included to
provide an ink including a dye of the desired
intensity. Preferred inks may include between 1% and
3%, and more preferably approximately 2%, of the
organic acid by weight.
The polyacrylate film-forming polymer can
impro~e the color intensity and reduce feathering from
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write-over. Examples of polyacrylate ~ilm-forming
polymers include Sokalan CPlos, CP12s, and PA13PN, all
of which are available from BASF. Enough polyacrylate
film-forming polymer should be included in the ink to
provide the targeted benefit, but not 80 much should be
included that the viscosity of the ink becomes
undesirably high. Preferred inks may include between
1% and 5%, and more preferably between 2% and 4%, of
the polyacrylate film-forming polymer by weight.
Enough water should be included in the ink to
dissolve the components and provide the ink with the
desired viscosity. Preferred inks may have a viscosity
betwee~ 1 cps and 3 cps, and more preferably between 2
cp8 and 2.5 cps. Preferred inks may include between
15 75% and 85% water by weight.
The non-volatile amine in the eradicator
fluid causes the triaryl methane dye to decolorize when
t~e ~iuid is appli~d ov~r a mark madc with th~ ink.
The amine selected, in addition to preferably being
20 non-volatile, should be non-toxic, and preferably
odorle~s. Examples of preferred ~m; ne~ include glycine
~in the form of sodium glycinate), other amino acid
salts and polyAm;~e~
Enough amine is included in the eradicator
25 fluid to decolorize the dye when applied in reasonable
~uantities to a mark made with the ink. But large
guantities of amine may inter~ere with the ability of
the metal salt in the ink to sufficiently prohibit
fading of a corrective ink marking applied to the
30 hardened eradicator fluid. Preferred eradicator fluids
may include between 7% and 12%, and more pre~erably
J between 8% and 10%, of the amine by weight.
The ~ilm-~orming polymer increases the
viscoRity of the eradicator fluid. It also may
35 decrease writeover time by providing a thin film on the
~urface of a covering made with the eradicator fluid;
the thin film increases the hardness of the surface,
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and may make the surface ~uitable to receive a mark
made with ink even though the eradicator fluid has not
fully dried. The film-forming polymer should be
compatible with the amine used in the eradicator ~luid.
Preferred film-forming polymers are sodium salts of
polyacrylic acids. Preferred polyacrylic acid film-
forming polymers have a number average molecular weight
of ~etween 1200 and ~000.
A sufficient ~uantity of the film-forming
polymer is included in the eradicator fluid to provide
the desired film and viscosity. Too much film-forming
polymer may raise the viscosity to undesirable levels.
Preferred eradicator fluids may include between 15% and
25%, and more preferably approximately 20%, of the
film-forming polymer by weight.
Enough water should be included in the
eradicator fluid to dissolve the components and provide
the fluid with the desired viscosity. Preferred
eradicator fluids may have, for example, a visco~ity
between 5 cp~ and 15 cps, and more preferably between 6
cps and 7 cps.
The eradicator fluid also preferably contains
a buffer to maintain the pH of the solution at~ for
example, between 11 and 12 (more pre~erably at
approximately 11.7). Preferred eradicator fluids may
include, for example, between 75% and 85% of the
a~ueous buffer solution by weight.
The surface ten~ion of the ink and the
eradicator fluid can impact the eradication and
writeover performance of the eradicator system. The
surface tension of the ink preferably i~ between 30
dynes/cm and 4~ dyne~/cm, and more preferably i~
approximately 40 dynes/cm. The surface tension of the
~radicator fluid preferably is between 20 dynes/cm and
40 dynes/cm, more preferably is between 25 dynes/cm and
35 dynes/cm, and most preferably is approximately 30
dynes/cm. The surface tengion of the ink and
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eradicator fluid may be adjusted using conventional
surfactants. If the surface tension of the ink i8 too
? low, the ink may penetrate too far into a paper
substrate too quickly relative to the eradicator fluid
that subsequently is applied. If the surface tension of
the eradicator fluid i8 too high it may not penetrate
into the paper as far, or at least as quickly, as the
previously applied ink. This could lead to either
incomplete eradication or an extended eradication time.
Other conventional ingredients such as
bactericides, thickeners, and colorants can be included
in the ink or the eradicator fluid.
The preferred inks and eradicator fluid~ can
be used in roller ball point pens, e.g., pens which
include a tubular member for fluid ~mm~ln;cation with a
reservoir (either a fiber or hollow reservoir); a
socket, having a seat, at one end of the member, an
interior wall surface ext~n~;n~ from the seat; a rim
disposed at the end of the interior wall surface
opposite the seat; and a spherical ball that is
disposed in the socket, rotatably engagable with the
seat and captured by the rim. The writing instrument
may also include, for example, a felt tip. The inks
and eradicator fluids may also ~e ~sed in fountain
pens.
In one ~hoA;m~nt, the ink and the eradicator
~luid are supplied in separate pens. If desired,
several ink contA;n;n~ pens may be provided, each pen
contA;n;ng an ink.
In another embodiment, the ink and the
eradicator fluid are supplied in a single pen,
cont~;n;ng a reservoir for each. Each reservoir may be
either a hollow or fiber reservoir. The two reservoirs
J are surrounded by a tubular member, e.g., a
pol~lo~ylene barrel. If the pen is a marker, it
includes nibs at opposite ends, each nib being covered
by a cap. An example of a suitable nib is the
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polyethylene chisel nib available from Interflo.
Alternatively, if it is a roller ball point pen it
includes a ball and socket structure, as described
above and as is well known in the art, at each end.
The ink reservoir may be large enough, for example, to
include approximately three times as much fluid a~ the
eradicator ~luid re~ervoir.
The inks and eradicator fluids may be
prepared by m; Yi ng the components.
~Y5~ ?le 1
An ink was prepared by ~i~ n~ 4 parts Acid
Blue 93 (available from Orient), 2 parts citric acid,
10 parts magnesium sul~ate, 2.5 parts Sokalan CP10
(available from BASF) and 81.5 parts water.
An eradicator fluid was prepared by m; Y; n~ 10
parts sodium glycinate, 20 parts polyacrylic acid
sodium salt (cat. no. 42034-4, available from Aldrich),
0.2 parts surfactant (Dynol, avai~able from Air
Products) and 70 parts of an aqueous buffer solution
~pH 11.7). One liter of the buffer solution included
1.4841 g of boric acid, 4.1050 g of sodium hydroxide,
1.4 ml of acetic acid, and 1.4 ml of phosphoric acid.
The ink wa~ used to write on Ampad note paper
~available, ~or example, from Pha~e One Office Product~
Co., cat. no. AMP-20-372). The eradicator fluid was
applied over a portion of the ink mark. After the
eradicator f}uid had hardened sufficiently, corrective
ink marking was applied. No fading or feathering of
the corrective marking was observed.
3 O F.Y5~TII~ le 2
An eradicator fluid was prepared by ;~; n~
10% ~by total weight) zinc sulfate, 2.5% Sokalan CPlOs,
21 citric acid, 41 Acid Blue 93, and 81.51 water.
~le 3
An eradicator fluid was prepared by ~;Y; n~ 5%
~by total weight) zinc sulfate, 5% magnesium sulfate,
2.5~ So~alan CPlOs, 2% citric acid, 4% Acid Blue 93,
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and 81.5% water.
Other embodiments are within the claims. For
example, an eradicator fluid can be u~ed in combination
with two inks, one including a metal nalt that binds
the amine in the eradicator fluid, the other lacking
the metal ~alt. An ink mark can be made on paper with
the ink lacking the metal ~alt, and the eradicator
~luid applied to decolorize the dye. A corrective
marking then can be made with the ink including the
metal ~alt.
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