Note: Descriptions are shown in the official language in which they were submitted.
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OZONE-FRIENDLY CORRECTION FLUID WITH IMPROVED
OVERWRITE CHARACTERISTIC
The invention relates to correction
fluids.
Correction fluids are used for
correcting handwritten, typewritten, photocopied,
or laser printed markings on paper. Generally,
correction fluids are applied to a paper surface
over an erroneous marking in liquid form. The
fluid subsequently forms a film which effectively
covers erroneous markings on the surface and can
receive a correct marking. Making a corrective
marking over the film commonly is known as
"writeover".
Correction fluids typically include some
standard ingredients, including an opacifying
pigment (commonly titanium dioxide), a film-
forming polymeric material, and a solvent.
The opacifying pigment is dispersed in
the fluid and provides the basic white color which
can be toned with other pigments to provide a
correction fluid closely corresponding to the
color of the paper to which the fluid is to be
applied. The opacifying pigment functions to
obscure the erroneous marking over which the
correction fluid is applied.
The film-forming polymeric material,
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also known as the binder, binds the pigment to the
paper and helps to form a flexible but continuous
covering that remains once the solvent has dried. r
The solvent is used as the carrier for
the other ingredients in the fluid. Historically,
halogenated hydrocarbons have been the solvents of
choice for correction fluid compositions.
Halogenated hydrocarbon solvents present special
advantages primarily because they have evaporation
rates which provide correction fluids that dry
rapidly and completely. Additionally, they do not
interact with typewritten markings to cause
unacceptable bleeding. Also, they can effectively
dissolve those film-forming polymeric materials
which provide durable but flexible films without
causing excessive cockling or distortion of paper
surfaces. Despite their recognized advantages
when used as correction fluid solvents, the use of
halogenated hydrocarbon solvents has become a
matter of increased concern primarily because of
their adverse effect on the environment
(stratospheric ozone depletion). Accordingly,
providing an "ozone-friendly" correction fluid by
eliminating the use of halogenated hydrocarbon
solvents has become desirable. By ozone-friendly
correction fluid, we mean a correction fluid which
either does not contain a material that migrates
to the stratosphere or, if it contains such a
material, the material does not cause a reduction
in the ozone concentrations.
Attempts have been made to replace the
halogenated solvents with non-halogenated '
alternatives. Aqueous-based systems such as those
described in U.S. Patent No. 5,332,599 are not
effective for a wide variety of ink formulations.
Alternatively, non-halogenated hydrocarbon
solvents, such as those described in U.S. Patent
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Nos. 5,199,976 and 5,306,755 cover a wide range of
ink types, but suffer from poor overwrite
characteristics.
It is a object of the present invention
to provide a correction fluid based on a non-
halogenated solvent system with improved overwrite
characteristics.
Generally, the invention relates to an
ozone-friendly correction fluid that has improved
writeover characteristics. The ozone-friendly
correction fluids thus have a key benefit (good
writeover characteristic) associated with
halogenated hydrocarbon solvent-based correction
fluids, but also have the environmental benefits
associated with ozone-friendly solvent-based
correction fluids.
Specifically, the present invention
relates to an ozone-friendly correction fluid
comprising a non-halogenated hydrocarbon solvent,
a polymeric phase and an opacifying phase. wherein
the ratio of opacifying phase to polymeric phase
is from about 2.2 to about 3.8 preferably from
about 2.4 to about 3.6 (based on weight).
Other features and advantages of the
invention will be apparent from the description of
the preferred embodiment thereof, and from the
claims.
As used herein, the term "overwrite
characteristic" relates to a correction fluid
films ability to accept new written matter in the
form of inks. marker pens and typewriter impacts.
Without being bound to theory, applicants believe
that this characteristic is related to film
strength and paper adhesion. When correction
fluid films exhibit weak strength and poor paper
adhesion the overwrite characteristic is extremely
poor. This typically results in gouging and
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flaking of the correction fluid while new pen
markings are made on the film. Accordingly,
correction fluids which exhibit good "overwrite
characteristic" do not exhibit excessive flaking
or chipping during normal writing pressures. The E.
importance of a good overwrite characteristic is
very important with ink pen and typewriter
overwrite due to the relatively high pressures
applied. The importance of good overwrite
characteristic with marker pens is typically less
important.
According to the present invention, it
has been discovered that by ratioing the
opacifying phase with the polymeric phase of a
correction fluid based on a non-halogenated
hydrocarbon solvent it is possible to obtain
dramatically improved overwrite characteristics.
As used herein, the term "opacifying
phase" refers to the total amount of opacifying
agent found in the correction fluid. The
opacifying agents suitable for use in the present
invention include commercially available rutile
titanium dioxide, anatase titanium dioxide, zinc
sulfide, zinc oxide, calcium carbonate or blends
or mixtures of these materials. Preferably the
opacifying agent have an average particle size
between about 0.2 and about 0.4 microns and an
average oil absorption of about 14 lbs. oil/100
lbs. pigment to about 36 lbs. per 100 lbs. The
amount of opacifying agent can vary depending on
the degree of coverage desired (lower amounts will
provide poorer coverage while higher amounts will
provide extremely opaque coverage). From about 32
to about 55~ by weight opacifying agent based on
the total weight of the composition is generally
suitable. Preferably the opacifying agent is
selected from the group consisting~of rutile
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titanium dioxide and anatase titanium dioxide at
levels of from about 38 to about 52% by weight
based on the total weight of composition.
A,s used. herein, the "polymeric phase"
refers to tlhe film forming binder, (i.e. resin)
plasticizer;a, and. dispersants. Hinders suitable
for use in 'the present invention include
Thez~oplast:ic butyl methacrylate (BMA) copolymer
(such as Neocryl B 705 or Neocryl*H700 polymer
manufactured by Zeneca Resins, Wilmington, MA or
Rohagum*P 6'75 supplied by Rohm Tech Inc., Malden,
MA); vinyl toluene-butadiene copolymer (such as
those manufactured by Goodyear Chemicals);
isobutyl me~thacrylate polymer (IBMP) (Acryloid*
867, manufactured by Rohm & Haas, Philadelphia,
PA); n-buty:L methacrylate polymer (such as
Elvacite 2044 manufactured by DuPont Chemical,
Wilmington, DE); n-butyl methacrylate/isobutyl
methacrylate copolymer (such as Elvacite 2046
manufactured by DuPont Chemical) and mixtures
thereof. Suitable "plasticizers" include
ditridecyl phthalate. Suitable dispersants
include dio<:tyl sodium sulfosuccinate and
polymeric fatty ester (Hypermer LPl manufactured
by ICI Amer:LCas); and mixtures thereof.
As used herein, suitable "non-
halogenated hydrocarbon solvents" include any
cyclohexa.ne or alkylated cyclohexane and aliphatic
hydrocarbons containing 10 or fewer carbon atoms.
P=eferably the material is methylcyclohexane.
Optionally, correction fluids of the
present invention may also include other typical
correction fluid ingredients such as tinting
colorants, c:.g. lamp black, raw umber, yellow
oxide, etc. These tinting colorants are counted
as opacifying agents in the "opacifying phase"
calculation.. Also, a small amount of mustard oil
* Trade-mark
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(0.1 - 0.2$) is often added as a deterrent.
According to the present invention, an
Opacifying Phase to Polymeric Phase ratio in the
range of from 2.2 to 3.8 provides excellent
overwrite characteristics when compared with
conventional non-halogenated hydrocarbon solvent
correction fluid systems. Preferably, the
opacifying phase to polymeric phase ratio is from
2.4 to 3.6.
Examples
Examples 1-5 below illustrate fluids
with Opacifying Phase to Polymeric Phase ratios
according to the present invention provide good
overwrite properties at high wet fluid lay down,
e.g., five mils film thickness. Example 6 below
shows a ratio outside the claim range. In use,
the Example 6 correction fluid shows inferior
overwrite properties at high wet fluid lay down.
Example 1
Ing redients Wt.~
1. Methylcyclohexane 41.41
2. Thermoplastic IBMA Copolymer,
Neocryl B 705 Polymer 10.78
3. Ditridecyl Phthalate 3.99
4. Polymeric Fatty Ester,
Hypermer LP1 (ICI Americas,, Inc.) 2.22
5. Titanium Dioxide, Tipure R-931 41.39
6. Lamp Black 0.07
7. Mustard Oil 0.12
8. Fragrance 759292/0602185
(Haarmann & Reimer) 0.02
100.00
Opacify3.ag 2.44
Phase
to
Polymeric
Phase
Ratio:
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l~cample 2
Ing redients Wt.~
1. Methylcyclohe:Kane 42.30
2. Thermoplastic IBMA Copolymer,
Neocryl B 70!5 Polymer 9.65
3. Ditridec:yl Phthalate 3.57
4. Polymeric Fati~y Ester,
Hyperme:r LP1 (ICI Americas, Inc.) 1.98
5. Titanium Dioxide, Tipure*R-931 42.29
6. Lamp Black 0.07
7. Mustard Oil 0.12
8. Fragrance 759:?92/0602185
(Haarma.nn & Reimer) 0.02
100.00
Opacifying 2.78
Phase
t=o
Polymeric
Phase
Ratio:
Example 3
Ing redients Wt.~
1. Methylcyclohexane 40.17
2. Thermoplastic IBMA Copolymer,
Neocryl B 705 Polymer 9.16
3. Ditridecyl Phthalate 3.39
4. Polymeric Fatty Ester,
Hypermer LP1 (ICI Americas, Inc.) 1.88
5. Titanium; Dioxide, Tipure R-931 45.19
6. Lamp Black 0.08
7. Mustard Oil 0.11
8. Fragrance 759:'92/0602185
(Haarma.nn & Reimer) 0.02
100.00
Pigment 3.13
to Hinder
Ratio:
* Trade-mark
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Example 4
In gredients Wt.%
1. Methylcyclohexane 39.69 ,
2. Thermoplastic IBMA Copolymer,
Neocryl B 705 Polymer 8.52
3. Ditridecyl Phthalate 3.15
4. Polymeric Fatty Ester,
Hypermer LP1 (ICI Americas, Inc.) 1.75
5. Titanium Dioxide, Tipure R-931 46.68
6. Lamp Black 0.08
7. Mustard Oil 0.11
8. Fragrance 759292/0602185
(Haarmann & Reimer) 0.02
100.00
Opacifying 3.48
Phase
to
Polymeric
Phase
Ratio:
Example 5
Inc tredients Wt . ~
1. Methylcyclohexane 46.21
2. Vinyl Toluene-Butadiene
Copolymer (Goodyear Chemicals) 9.68
3. Ditridecyl Phthalate 2.64
4. Polymeric Fatty Ester,
Hypermer LP1 (ICI Americas, Inc.) 1.65
5. Titanium Dioxide, Tipure R-931 39.60
6. Lamp Black 0.07
7. Mustard Oil 0.13
8. Fragrance 759292/0602185
(Haarmann & Reimer) 0.02
100.00
Opacifyiag 2.83
Phase E
to Polymeric
Phase
Ratio:
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Example 6
IncTredients Snit.
1. Methylcyclohexane 48.91
2. Vinyl Toluene-Butadiene
Copolymer (Goodyear Chemicals) 8.53
3. Dioctyl Sodium Sulfosuccinate 1.56
4. Titanium Dioxide, Tipure R-931 40.79
5. Lamp Black 0.07
6. Mustard Oil 0.14
100.00
Opacifying Phase to Polymeric Phase Ratio: 4.04
The correction fluids containing the
above ingredients were prepared by first
dissolving the binder in the solvent system.
Next, the dispersant, plasticizer and opacifying
agent were added and the mixture was dispersed for
3 hours in a bead mill after lamp black and
mustard oil were added to obtain final fluid
composition.
Other embodiments are within the claims.
For example, in addition to the most preferred
ingredients the composition may also include
various additives known to those skilled in the
art. These additives are incorporated to improve
specific properties. These include flattening
agents to control film-glow, flow additives and
thickeners to control brushing, leveling and
' settling and pigment extenders to reduce cost.
