Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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POLYSACCHARIDE-BASED PROTECTIVE COATING
COMPOSITIONS AND METHODS OF USE THEREOF
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part of 09/557,023, filed on April 20, 2000 which is
a continuation-in-part of USSN 09/122,224, filed on July 24, 1998 which is a
continuation-
in-part of USSN 08/382,359, filed on February 1, 1995, all of which are
incorporated herein
by reference in their entirety for all purposes.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY
SPONSORED RESEARCH AND DEVELOPMENT
[ Not Applicable ]
FIELD OF THE INVENTION
The present invention relates to the field of protective coatings to be used
during coating operations of various surfaces including surfaces of vehicles
or buildings. More
specifically, in one embodiment the invention provides an improved method and
composition
for masking selected portions of a surface, in particular a vehicle surface,
from paint. In
another embodiment, this invention provides methods and compositions for
protecting surfaces
(e.g. walls and/or floors) of a paint spray booth from paint overspray.
BACKGROUND OF THE INVENTION
It is well known that painting operations often require mashing of certain
portions of the surface of the painted obj ect to prevent overspray. For
example, it is often
necessary to mask trim and windows on a vehicle (e.g., a motor vehicle) from
paint overspray.
Also, building stucco must frequently be protected from paint or primer coats.
On occasion, it
is necessary to mask painted portions of a vehicle or building from paints of
a different color
and overspray of paints of the same color. In addition, it is often desired to
protect the surfaces
(e.g. floors or walls) of the area (e.g. paint spray booth) in which the
overcoating (e.g. painting)
operation is performed.
In practice, mashing operations are often one of the most time consuming and,
therefore, expensive parts of the painting process. In spite of attempts to
develop suitable
chemical masks for vehicle painting, vehicle painters continue to use
primarily masking tape
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and paper to cover portions of a vehicle where paint is not desired. To mask
the trim on a car,
for example, will often require many hours of tedious labor. Furthermore, even
when done
carefully, defects in such paint masks allow paint to contact surfaces that
are desired to be
protected.
Chemical masking solutions have been proposed to the problem of protecting
surfaces during coating processing operations. However, such techniques have
often not found
extensive use. Some of the proposed chemical masks have been unsuitable for
application to
portions of a vehicle or building because of damage which would potentially
occur to the
protected portions of the vehicle or building. Other compositions are not
water-soluble which
increases the difficulty and expense of removal. In addition, masks that
require solvents for
removal are problematic in view of the increasing regulation of disposal of
solvents as
environmental regulation becomes stricter with time. Other compositions are
difficult to apply,
difficult to remove, excessively costly, or the like.
From the above it is seen that an improved masking that is easily applied and
removed, that provides good surface protection, that is economical, and whose
use entails little
or no environmental impact is needed.
SUMMARY OF THE INVENTION
An improved mashing composition and method is provided by virtue of the
present invention. The method includes the steps of applying a substantially
continuous film
of a masking material on a vehicle (e.g. motor vehicle), building, floor, wall
(e.g. spray booth
floor wall or other spray booth surface) or other surface to be protected
during a "coating
operation" such as painting. The vehicle, building, or other surface may then
be coated with a
"coating compound" such as paint or any other compound which is to be applied
to the surface.
Finally, the masking material may be removed from the surface by washing with
water thereby
removing any coating compound that may be present on the masking material.
These steps
may be performed, for example, during an assembly line production of a vehicle
or other
article of manufacture.
By "coating operation" or "overcoating" it is desired to include any compound
which is applied to a surface. Coating compounds include materials such as
paint or other
finishing materials such as lacquer, varnish, waxes and the like which adhere
to the surface to
which they are applied thereby forming a relatively permanent finish. Coating
compounds,
however, may also include compounds designed for temporary application to
surfaces as in
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surface preparative treatments such as acids, oils, and antioxidants from
which it may be
necessary or desired to shield other surfaces.
By "building" it is intended to mean herein a house, warehouse, apartment,
garage, store, or the like. By "vehicle" it is intended to mean herein a car,
boat, plane, train,
railroad car, or the like. By "substantially continuous film" it is intended
to mean herein a film
lacking pinholes through which paint or other materials generated during a
coating operation
processing could reach an underlying surface.
The masking material is, in one embodiment, a composition comprising 36. A
composition for temporarily protectiilg a surface, said composition comprising
an aqueous
solution/suspension of a polysaccharide (e.g., staxch, carboxymethyl
cellulose, hydroxyethyl
cellulose, hydroxypropyl cellulose, algin, gum arabic, alginic acid, a
cellulose gum, etc.)
typically present in an amount ranging from about 2 to about 90 weight percent
of said
maslcing material, wherein said polysaccharide is not a dextrin; and a
plasticizes present in an
amount sufficient to prevent cracl~ing of the protective film formed when the
masking material
is dried, where the composition, when applied to a painted automobile surface,
dries to a dry,
protective coating that protects the underlying surface from paint and that is
removable with a
water wash. Typically the composition, when applied to a painted automobile
surface, dries to
a dry continuous film that protects the underlying surface from paint in a
painting operation
and can readily be removed from the underlying surface with a water wash
without marring or
disfiguring the underlying surface. In preferred embodiments, the
polysaccharide is present in
an amount ranging from about 2 to about 50 weight percent of said masking
material. In
certaiil embodiments, the polysaccharide is not and does not comprise a
cellulose or a cellulose
derivative. In particularly preferred embodiments, the plasticizes comprises a
simple sugar
(e.g. glucose, sucrose, and fructose) and/or a material selected from the
group consisting of
sorbitol, glycerin, sucrose, urea, polyethylene glycol, polypropylene glycol,
polyglycerol, and
glycerol. In certain embodiments, the plasticizes is present in an amount
ranging from about
0.2 to about 12 weight percent of the mashing material. The masking material
can further
comprise a surfactant, preferably in an amount effective to produce a coating
that lays out
smoothly in a substantially continuous film (e.g. typically at an amount up to
about 2%, by
weight, of the masking composition). Preferred surfactants include, but are
not limited to an
anionic surfactant, a cationic surfactant, a nonionic surfactant, and an
arnphoteric surfactant.
Particulalry preferred surfactants comprise a fluorinated surfactant. The
masking material can
further comprise an alcohol (e.g. a straight chain alcohol such as ethanol,
methanol, propanol,
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etc.). The alcohol, when present typically ranges from about 0.5 percent to
about 12 percent by
weight of the masking material. The masking material can further comprises a
thickener (e.g.
a neutralized crossliuked acrylate copolymer, a neutralized crosslinked
polyacrylic acid, a
neutralized polyacrylic acid, an algin, a carboxy methyl cellulose, a
neutralized
polymethacrylic acid, a neutralized ethylene-acrylic acid copolymer, methocel,
gum arabic, a
cellulose gum, a neutralized styrene acrylic acid copolymer, etc.). When
present the thickener
preferably ranges from about 0.1 to about 30 weight percent of the mashing
material, more
preferably from about 0.5 to about 5 or 10 weight percent of the masking
material. The
maslcing material can also comprise a preservative.
In certain preferred embodiments, the polysaccharide is selected from the
group
consisting of starch, carboxymethyl cellulose, hydroxyethyl cellulose,
hydroxypropyl
cellulose, algin, gum arabic, alginic acid, and a cellulose gum; and the
masking material further
comprises a surfactant. The masking material can further comprise a thickener
(e.g. EP-1)
and/or an alcohol. Tn a particularly preferred embodiment, the polysaccharide
is present in an
amount ranging from about 1 to about 20 weight percent of the masking
material; the
plasticizer is present in an amount ranging from about 1 to about 15 weight
percent of the
masking material; .the masking material further comprises a thickener ranging
from about 0.1
to about 5 weight percent of the masking material, and the masking material,
optionally
includes a preservative. In another particularly preferred embodiment, the
polysaccharide is
present in an amotmt rang>lzg from about 1 to about 20 weight percent of the
masking material;
the plasticizer is sorbitol ranging from about 3 to about 8 weight percent of
the maskiizg
material; the thickener ranges from about 0.1 to about 5 weight percent of the
mashing
material, and a preservative is optionally present. In one most preferred
embodiment, the
polysaccharide is present at about 5 weight percent of the masking material;
the plasticizer is
sorbitol at about 3.4 weight percent of the masking material; the thickener is
present at about
0.72 weight percent of said masking material; and the masking material further
comprises a
preservative. In certain embodiments, the polysaccharides are not cellulose or
cellulose
derivatives.
In another embodiment, this invention provides masking materials comprising
dextrin as a film former. Preferred compositions comprise an aqueous
solution/suspension of
i) a dextrin present in an amount ranging from about 2 to about 90 weight
percent of the
composition; a plasticizer present in an amount sufficient to prevent cracking
of the film
formed when the composition is dried; and a thickener present in an amount
ranging from
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about 0.5 to about 5 weight percent of said composition. Preferred
compositions, when
applied to a painted automobile surface, dry to form a dry continuous film
that protects the
underlying surface (e.g. a painted automobile surface) from paint in a
painting operation and
that can be removed from the underlying surface with a water wash without
marring or
disfiguring the underlying surface. In certain embodiments, the dextrin (e.g.,
tapioca
dextrin, com dextrin, potato dextrin, maltodextrin, etc.) is present in an
amount ranging
from about 2 to about 50 weight percent of the composition.
In particularly preferred embodiments, the plasticizes comprises a simple
sugar
(e.g. glucose, sucrose, and fructose) and/or a material selected from the
group consisting of
sorbitol, glycerin, sucrose, urea, polyethylene glycol, polypropylene glycol,
polyglycerol, and
glycerol. In certain embodiments, the plasticizes is present in an amount
ranging from about
0.2 to about 12 weight percent of the masking material. The masking material
can further
comprise a surfactant, preferably in an amount effective to produce a coating
that lays out
smoothly in a substantially continuous film (e.g. typically at an amount up to
about 2%, by
weight, of the masking composition). Preferred thickeners include, but are not
limited to a
neutralized crosslinked acrylate copolymer, a neutralized crosslinked
polyacrylic acid, a
neutralized polyacrylic acid, an algin, a carboxy methyl cellulose, a
neutralized
polymethacrylic acid, a neutralized ethylene-acrylic acid copolymer, methocel,
gum arabic,
a cellulose gum, and a neutralized styrene acrylic acid copolymer. The
thickener preferably
ranges from about 0.5 to about 5 weight percent of the composition and more
preferably
from about 0.5 to about 1 weight percent and most preferably comprises about
0.72 weight
percent of said composition. One particularly preferred thickener is a
crosslinked acrylate
copolymer (e.g. EP-1).
hl certain embodiments, the composition further comprises an alcohol (e.g. a
straight chain alcohol such as ethanol, methanol, propanol, etc.). The
alcohol, when
present, is typically present in a concentration ranging from about 0.5
percent to about 12
percent by weight. The composition can, optionally, further comprise a
preservative. '
In certain embodiments, the said dextrin is present in an amount ranging
from about 1 to about 20 weight percent of the composition; the plasticizes is
present in an
amount ranging from about 1 to about 15 weight percent of said composition;
the thickener
is present at about 0.72 weight percent of the composition, and the
composition, optionally
includes a preservative. In certain particularly preferred embodiments, the
dextrin is a
maltodextrin ranging from about 1 to about 10 weight percent of the
composition; and the
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plasticizer is sorbitol ranging from about 1 to about 5 weight percent of the
composition. In
other particularly preferred embodiments, the dextrin comprises about 5 weight
percent of
the composition.
This invention also provides methods of use of the compositions (masking
materials) described above. In one embodiment, this invention provides a
method of
temporarily protecting a surface in a coating operation. The method involves
a) applying
one or more of the masking materials described herein to the surface, whereby
the applying
resulting in a substantially continuous film of the masking material; b)
coating all or a
portion of the surface with an overcoating compound (e.g. a paint or lacquer),
whereby the
masking material prevents the coating compound from contacting the underlying
surface;
and c) removing the masking material from the surface whereby the coating
compound
applied to the surface covered with the masking material is removed together
with the
masking material. In certain embodiments, the surface comprises a surface of a
motor
vehicle (e.g. a car, truck, motorcycle, etc.). In certain embodiments, the
surface comprises a
surface of a paint booth (e.g. floors, and/or walls, and/or ceiling).
In still another embodiment, this invention provides articles of manufacture
comprising a surface coated with a protective "masking" composition as
described herein.
This invention also provides a method of storing or transporting a vehicle
having a painted surface. The method involves coating the painted surface with
a protective
"masking" composition described herein, drying the composition to form a dry
protective
film; storing or transporting the vehicle; and washing the dry protective film
from said
vehicle with a water wash.
BRIEF DESCRIPTION OF THE DRAWINGS
[ Not Applicable ]
DETAILED DESCRIPTION
I. Protective coating compositions and their use.
The present invention provides improved methods and compositions for
protecting a vehicle (e.g. motor vehicle) or other surface subj ect to a
coating operation such as
painting, or for protecting a surface of an article manufacture during an
assembly operation.
For example, in one embodiment, certain regions of an automobile, or other
surface, may be
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masked using the coating compositions of the present invention to protect
those regions from
paint overspray in a painting booth. In another embodiment, an article of
manufacture (e.g. an
automobile panel) may be protected from mechanical impact and/or abrasion by
the presence
of such an overcoating.
In addition it is also often desired to protect the surfaces of the area in
which an
overcoating operation (e.g. painting) is performed. In particular, it is
desired to protect the
walls, floors and other surfaces of such an area (e:g. a painting booth) from
paint overspray and
spills. In addition, it is also desirable to reduce airborne dust in such
areas during overcoating
operations.
This invention provides compositions and methods to meet these needs. In
preferred embodiments, the methods entail coating the surface to be protected
(e.g. surface of a
car or truck or the walls andlor floors of a spray booth) with a temporary
protective coating
composition. One or more coating (e.g. painting) operations, and/or
mechanical/handling
operations are performed and, when desired, the protective composition is
removed (e.g. by a
simple water wash).
The coating compositions of this invention, when applied to a surface (e.g.
the
surface of an automobile), produce a substantially continuous dry filin that
adheres well to the
underlying surface. By "substantially continuous filin" it is intended to mean
herein a film
generally lacking pinholes through which, oil, paint, dust, or other materials
could reach the
underlying surface. Further, the material can be removed easily from the
surface to be
protected after use with a water wash, or by mechanical means such as scraping
or peeling, or
by combinations of these methods. W addition, because the material is
biodegradable, it may
be simply disposed of (e.g., washed down a sewer) with no substantial
environmental impact.
In particularly preferred embodiments, the coating compounds of this invention
utilize polysaccharides (e.g. dextrins, cellulose derivatives, starches, etc.)
or, more generally,
carbohydrates (e.g. compounds or molecules typically composed of carbon,
oxygen and
hydrogen in the ratio of 2H:1 C: l O, including, e.g., simple sugars such as
sucrose and fructose
or complex polysaccharide polymers such as chitin.), optionally in combination
with various
thickeners, as a film former. When formulated as described herein, the
polysaccharide or
carbohydrate compositions provide effective protection of an underlying
surface against paint
spray, mechanical insult, and the like. It was a particularly surprising
discovery of this
invention that the polysaccharide coatings described herein, can be applied to
a painted
automobile surface, effectively protect the underlying surface during a
commercial painting
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operation (e.g. spray painting, temperature cycling, etc. ), and are easily
washed off leaving the
underlying surface in pristine condition.
It was also a discovery of this invention that the polysaccharide (e.g.
dextrin)
and water based compositions of this ilzvention neutralize the isocyanates
typically found in
many overcoating compositions (e.g. automobile paint). Because the isocyanates
are
neutralized by contact with the coating composition, they may also be washed
away with the
protective coating with no substantial environmental impact.
A preferred method of protecting surfaces according to this invention includes
steps of applying the coating compositions to the surface to be protected in a
substantially
continuous film. The compositions are then dried to form a coating that
protects the
underlying surface from the coating operation (e.g. pailit overspray). The
coating may be
subsequently removed from the surface by simply washing with water when it is
longer
required. In a particularly preferred embodiment, the coatings of the present
invention are used
to protect components of motor vehicles (e.g. automobiles or automobile
surface finishes), and
the walls and floors of spray booths or other areas or structures that may be
contacted with
overspray in a coating (e.g., pailzting) operation.
In one embodiment, the coatings of this invention include a polysaccharide
(e.g. a dextrin), a plasticizer and water. The polysaccharide comprises from
about 2 percent to
about 90 percent, preferably from about 5 percent to about 80 percent, more
preferably from
about 5 percent to about 50 or 60 percent, by weight of the composition before
drying. In
certain embodiments, the polysaccharide film former (e.g. a dextrin) is
combined with a
thickener and is then preferably present in lower concentrations (e.g. about 2
percent to about
80 percent, preferably about 5 percent to about 70 percent, more preferably
from about 7
percent, about 10 percent, about 15 percent, or about 20 percent to about 80
percent, about 70
2S percent, about 60 percent or about 50 percent.
In one preferred embodiment, the polysaccharide is a dextrin which comprises
from about 2 percent to about 50 or 60 percent, more preferably from about 2
percent to about
or 40 percent, most preferably from about 5 percent to about 20 or 30 percent,
by weight, of
the composition. In certain high-solids formulations, the polysaccharide
comprises about 10 to
30 about 80 percent, preferably about 15 to about 60 percent and most
preferably about 20 to
about 40 percent, by weight, of the composition. One particularly preferred
embodiment
comprises about 30 to 40 percent, by weight, dextrin.
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II. Polysaccharides as film formers.
In various embodiments, the compositions of this invention utilize one or
more polysaccharides as film formers. A wide variety of polysaccharides are
suitable for
use in the present invention. Such polysaccharides include, but are not
limited to
hemicelluloses (e.g. axabinoxylans, glucomannans), plant gums (e.g. guar gum,
locust bean
gum) cellulose and derivatives thereof (e.g. ethyl celluloses, hydroxytehyl
celluloses,
carboxymethyl celluloses), starch and starch derivatives (e.g. hydroxyethyl
starch),
microbial polysaccharides (e.g. xanthan gum, curdlan, pullulan, dextran),
algal
polysaccharides (e.g. agar, carragenans, alginic acid), chitin, chitosan and
their derivatives,
and the like. Particularly preferred polysaccharides include, but are not
limited to starch,
caxboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose,
algin, dextrin,
gum Arabic, alginic acid, or a cellulose gum. In a most preferred embodiment,
the
polysaccharide is a dextrin (e.g., a tapioca dextrin, corn dextrin, potato
dextrin, a
maltodextrin, etc.).
Some polysaccharides are conveniently made into films by precipitation
from an aqueous solution under evaporation (e.g. locust bean gum, dextran,
xanthan). Other
polysaccharides must be solubilized in alkaline media (e.g. curdlan and other
[3-1,3-
glucans). When neutralized some of these will form supersaturated solutions
capable of
forming films on evaporation. Some of the polysaccharides will pass over a gel
state before
forming films.
The concentration of the polysaccharide used in the solution thereof may
waxy within broad limits and the solutions may contain from about 2 percent up
to about 90
percent, with preferred concentrations being as indicated above.
In certain preferred embodiments, the molecular weight of the
polysaccharides ranges from about 50 Da to about will be about 10,000 Da,
preferably from
about I00 Da to about 5,000 Da, more preferably from about 500 Da to about
3000 Da, and
most preferably from about 1000 Da to about 3,000 Da.
Mixtures of two or more polysaccharides may, of course, be used if desired,
and such combinations of two polysaccharides. In addition, mixtures of two or
more
polysaccharides in which one is typically regarded as a thickener are also
preferred in
certain embodiments.
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It is important to note that the process of the invention when practically
utilized results in a dry, solid, film, in which the polysaccharides are
typically present in an
essentially amorphous state. As indicated above, preferred polysaccharides
include, but are
not limited to, various cellulose derivatives, and starch and various starch
derivatives, with
dextrins being most preferred.
In a particularly preferred embodiment, the protective compositions of this
invention utilize dextrins as film formers. Dextriils are widely known as
products of the
hydrolysis of starch, often by amylases. More specifically, dextrins are
polymers of D-
glucose, characterized by an a,(1-4) linkage, which are intermediate in
complexity between
starch and maltose. The viscosity of dextrins, in aqueous solution, varies
depending on dextrin
length and degree of branching. However, compared with the original starch,
dextrins produce
aqueous solutions of lower viscosity. Commercially available dextrin typically
comprises a
mixture of higher viscosity and lower viscosity dextrins. As used herein, the
term "dextrin"
refers to that combination of higher and lower viscosity dextrins as would be
obtained in a
1S typical commercial preparation such as Amaizo 1895 (Cerestar C*+08602),
1890 (Cerestar
C*+08601), and 1885 (produced by American Maize Products Co., now owned by
Cerestar),
Amiogum 3S (EmCap06377), and the like. Preferred dextrins have a viscosity
ranging from
about 12 to about 20 seconds, more preferably from about 12 to about 1 S
seconds, and most
preferably about 12 seconds in an aqueous solution comprising 40 percent
solids (dextrins), as
measured using a number 3 Zahn cup. When measured as an aqueous solution
comprising
about SO percent solids (dextrin) a most preferred dextrin has a viscosity
ranging from about 95
to about 100 centipoise. One such preferred dextrin is an off specification
Amaizo 1895
designated Amaizo 2686N dextrin, available from American Maize Products, Co.).
While the "Amaizo" dextrins are derived from maize, dextrins derived from
2S other sources are also suitable. These include native dextrins of any
origin, synthetic,
natural or hybrid, derived, for example from potatoes, manioc, corn, waxy
corn, corn with
high amylose content, wheat, rice, and the like. Other preferred embodiments
utilize
tapioca dextrins (also known as crystal gum, see e.g. K4484 from National
Starch and
Chemical Col, Birdgewater N.J.) andlor maltodextrins (e.g., Star-Dri 180, A.E.
Stanley
Co.). Preferred maltodextrins are products produced from corn starches. They
are
classified by "dextrose equivalent" or DE, which is a measure of the reducing
sugars present
calculated as dextrose and expressed as a percentage of the total dry
substance. Preferred
maltodextrins have DE values of less than about 20, more preferably less than
about 1 S and
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most preferably have a DE value of about 10. By comparison, dextrose of
glucose has a DE
of 100.
Dextrin is utilized in the films of the present invention to provide solids
and
to build film thickness. It was an unexpected discovery of the present
invention, that the
use of dextrins provides masking compositions that show exceptional coating,
film forming,
and drying properties. In particular, the use of high concentrations of
dextrins allow the
buildup of a thick coating which nevertheless shows relatively low viscosity,
good coating
properties and an extremely rapid drying time. This is in dramatic contrast to
starch-based
compositions that typically cannot achieve comparable high solids
concentration. Starches
form highly viscous aqueous solutions that tend to gel at a solids
concentration far too low
to permit formation of a continuous protective film. Prior to the present
invention, it was
unknown and unsuspected that the use of dextrins would overcome this
limitation and form
the basis of an effective paint masking composition.
The quantity and type of dextrin in the coating composition may be
optimized for a particular application. This is accomplished empirically.
Generally where
it is desired that the composition dry to provide a thicker final coating more
solids (dextrin)
are added to the composition. However, the upper limits to dextrin
concentration are
dictated by the resulting viscosity of the composition. The viscosity of the
wet coating must
be low enough to permit application to and continuous coating of the surface.
Thus, in
order to produce a thick coating one increases the solids concentration, but
not beyond a
point where the composition becomes difficult or impossible to apply.
Conversely, where a
thin coating is desired, the solids composition may be decreased, but not to a
point where
the composition fails to form a continuous protective coating when dried.
It was a discovery of this invention, that where a thicker coating is desired,
maltodextrins are particularly effective. Moreover, the maltodextrins dry to
form a
somewhat taclcy coating and help to capture and retain airborne dust particles
thereby
helping to provide a reduced dust or dust-free environment for the overcoating
operation.
Because they produce a thick and relatively tough film, maltodextrins are
particularly well
suited in coating compositions designed for use on floors (e.g. floors of
paint booths).
Maltodextrins typically tend to yellow when subjected to drying cycles (heat).
However,
discoloration is rarely an issue for protective floor coverings.
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In contrast, tapioca dextrins tend to form thinner coatings that dry quickly.
The tapioca dextrins do not discolor on repetitive heating and hence are
particularly well
suited to applications on surfaces such as walls (e.g. the walls of a spray
booth).
To some extent, the optimal solids content of the mixture is a function of the
application method. It is expected that the composition may be applied by a
variety of
methods known to those of skill in the art. These methods include, but are not
limited to
painting, dipping, spraying, reverse roller coating, and the use of doctor
bars. One of skill
in the art will appreciate that application by spraying will generally require
a composition of
lower viscosity than application by the use of doctor bars. Thus a composition
intended for
application by spraying may contain a lower solids concentration than a
composition
applied by dipping or doctoring.
III. Plasticizers.
The coatings of the present invention also include a plasticizes to provide
toughness and flexibility and in particular to prevent cracking of the film
during drying and
subsequent handling. Suitable plasticizers are well lmown to those of skill in
the art and
include, but are not limited to glycerine, sorbitol, simple sugars (e.g.
glucose, sucrose,
Ievulose, dextrose, etc.), urea, triethylene glycol, polyethylene glycol,
polypropylene glycol,
polyglycerol, glycerol, and other water soluble plasticizers. These
plasticizers may be used
alone, or in combination with each other. A particularly preferred combination
of
plasticizers is urea in combination with glycerine or glycerine derivatives
such as glycerine
monostearate or glycerine monooleate. Another particularly preferred
combination is
glycerin in combination with sorbitol.
Sorbitol, urea and glycerine are most preferred as plasticizers. In one
preferred embodiment the plasticizes is simply sorbitol. When expressed as a
percentage of
the total coating compositions, the coatings utilizing urea as a plasticizes
preferably include
about 4 percent to about 12 percent urea, more preferably about 6 percent to
about 12
percent urea and most preferably about 7 percent to about 12 percent urea,
while the
coatings utilizing glycerine and/or sorbitol as plasticizes preferably include
about 0.8
percent to about 30 percent glycerine and/or sorbitol, more preferably about 3
to about 16
percent glycerine and/or sorbitol, and most preferably about 4% or 5% to about
10%
glycerine and/or sorbitol.
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In order to prevent cracking, the coatings of the present invention that are
force dried typically require a higher plasticizes concentration than the
coatings that are
simply air dried. Thus, coatings that are simply air-dried may contain
plasticizes in
concentrations near the lower end of the ranges provided above. Thus, the air-
dried
coatings contain about 4 percent (10 percent, by weight, of the dextrin) urea
or 0.8 percent
(2 percent, by weight, of the dextrin) glycerine. Conversely, force dried
coatings preferably
contain higher concentrations of plasticizes. Thus, the force-dried coatings
may contain
about 7.2 percent (18 percent, by weight, of the dextral ) urea or about 2
percent (5 percent,
by weight, of the dextrin) glycerine. Of course, coatings containing the
higher amounts of
plasticizes may be air dried as well. In addition, coatings containing the
lower amount of
plasticizes may often be successfully force-dried.
IV. Surfactants
The coatings of the present invention may additionally contain a surfactant.
Suitable surfactants include, but are not limited to anionic surfactants
(e.g., alkyl sulfates
(e.g. RhodaponTM), ether sulfates (e.g. RhodapexTM), sulfonates (e.g.
RhodacalTM),
dodecylbenzene sulfonates, alpha-olefin sulfonates, diphenyl oxide
disulfonates, phosphate
esters (e.g. RhodafacTM), carboxylates (e.g. Miranate~), etc.), cationic
surfactants (e.g.,
imidazolines (e.g. MiramineTM), ethoxylated amines (e.g. Rhodameen~, etc.),
non-ionic
surfactants (e.g., nonylphenol ethoxylates (e.g. Igepal CO series),
octylphenol ethoxylates
(e.g. Igepal CA series), nonionic esthers (e.g. Alkamuls~), oleyl alcohol
ethoxylates (e.g.
RhodasurfTM), ethoxylated mercaptans (e.g. Alcodet~), capped ethoxylates (e.g.
AntaroxTM), blocked polymers, etc.), and amphoteric surfactants (e.g.,
imidazoline
derivatives (MiranolTM), fatty amine derivatives (e.g., Mirataine~), etc.). W
certain
preferred embodiments, the masking composition includes nonionic alkyl aryl
surfactants
such as Triton CF-10 and CF-12 (Rohm & Haas, Philadelphia, Pennsylvania,
U.S.A.). Also
suitable is Triton X-100 and surfactants having fluorinated alkyl chains such
as "Fluorad"
products sold by Minnesota Mining and Manufacturing (St. Paul, Minnesota,
U.S.A.) and
"Zonyl" products sold by DuPont Company (Wilmington, Delaware, U.S.A.) are
also
suitable. In addition, many embodiments include polyethoxy adducts or modified
(poly)ethoxylates such as Triton DF-12 and DF-16 sold by Union Carbide
(Danbury,
Connecticut, U.S.A.). Other surfactants include nonylphenoxypolyethanol (such
as
IGEPAL CO-660 made by GAF), polyoxyalkylene glycol (such as Macol 18 and 19
made
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by Mazer Chemicals), acetylenic diol-based surfactants (such as Surfynol
104Atnade by Air
Products), and the like. Preferred compositions include up to 5 percent
surfactant. More
preferred compositions include less than 2 percent surfactant, and most
preferred
compositions include about 1 percent, or Less, by weight, surfactant.
To provide a continuous and level film, the masking composition should
adequately wet the surface to be protected. However, many surfaces, in
particular, car body
finishes, are themselves highly hydrophobic or purposely treated (e.g. waxed)
to have a low
surface free energy so that water will bead. To facilitate wetting and thereby
prevent the
maslcing composition from beading, the surface tension of the masking
composition may be
lowered by the addition of a surfactant.
A primary role of the surfactant in the masking composition is to wet the
substrate thereby leading to the formation of a continuous film. A
sufficiently continuous
protective film could be obtained with little or no surfactant so long as the
masking
composition contains a very high solids content (e.g., high concentrations of
dextrin). Fihns
containing high solids concentrations are often highly viscous and therefore
difficult to apply,
especially by spraying. While, as explained above, the use of dextrins allows
the production of
coatings with a high solids content, the use of surfactants or other wetting
agents is preferred as
coatings containing surfactants show superior film-forming properties in a
variety of
application methods.
In certain embodiments, the wetting properties of the coating compositions may
be improved by adding certain surfactant compositions, andlor by adding
various water soluble
alcohols such as propanol, methanol, or isopropyl alcohol, or by adding
aliphatic polyols such
as water soluble alcohols up to octanol. In particularly preferred
embodiments, surfactants are
used in the masking compositions of the present invention.
Preferred surfactants for use in the masking compositions of the present
invention should have certain beneficial properties. For example, they should
reduce the
surface tension of the composition to a sufficiently low value that a level
filin, free of pinholes,
is laid down. In most instances the surfactant will reduce the surface tension
of the masking
composition to at most about 25 dynes per centimeter, and more preferably to
at most about 20
dyne/cm. To avoid formation of pinholes, the surfactant should not foam.
Further, the
surfactant should work with a variety of surfaces such as those containing
silicones, acrylic
waxes, teflon~ waxes, clear coats, natural and hydrocarbon waxes, etc. Still
fiuther preferred
surfactants will be relatively inexpensive, will provide a product that does
not spot, streak, or
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frame (i. e., evaporate faster at edges such as moldiilg and/or trim) on the
surface to be
protected. Finally, the surfactant should be water soluble and otherwise
compatible with the
other components of the masking composition so that the composition does not
separate and
leave pinholes when dry.
Because many surfaces to be protected will have unusually low surface free
energies, the surfactant should be able to dramatically lower the surface and
interfacial tensions
of the masking composition. Compositions having very low surface tensions also
tend to
produce many fewer pinholes in the coating. Thus, any of the known classes of
very low
surface tension surfactants are preferred for use with this invention. One
such class is the
alkoxylates of fluorinated alkyl chains. Other functional derivatives (e.g.,
esters, sulfonates,
carboxylates, ammonium compounds, etc.) of fluorinated allcyl chaiizs also
tend to produce low
surface tension aqueous solutions. In general, replacement of hydrogens on an
alkyl group by
fluorine atoms leads to surfactants of unusually low surface tension. The
above mentioned
"Fluorads" and "Zonyls" are examples of surfactants having fluorinated alkyl
chains.
It has been discovered that a particularly preferred embodiment includes 2
percent of a 10 percent aqueous solution of CF-10 or Triton X-100 giving a
final concentration
of 0.2% surfactant. Another preferred embodiment utilizes a sulfonated
surfactant (e.g., D-40
or N-300 from BioSoft, Stepan Company) alone or in conjunction with one or
more fluorinated
surfactants (e.g., Fluorad FC 171 or FC 430, 3M Corporation). However, any
combination of
compatible surfactants that produce sufficient leveling on a given surface can
be used.
Particularly preferred compositions will provide a level film on a variety of
different surfaces
and will not spot, streak or frame when the film is rewetted.
The total surfactant in the material may include two or more different
surfactants. In some embodiments, a "bulk" surfactant from a different
chemical class will
be admixed with a fluorinated surfactant to promote low interfacial tension
and good
rewetting properties. Preferred bulk surfactants will allow the mask to be
rinsed off easily
without spotting or strealcing the underlying protected surface. Preferred
bulk surfactants
will produce very little or no foam during application or rinsing. They should
also be
relatively inexpensive. Suitable bulk surfactants include various compounds
such as
polyethoxylates and, in one case, octylphenoxypolyethoxyethanol. A
particularly preferred
bulk surfactant for use with Fluorad FC 171 and Fluorad FC 430 is Triton DF-
16, a
nonionic polyethoxylate or Turkey Red (Actrasol C-75, Climax Co.).
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One particularly preferred formulation includes not over 2% total surfactant,
but up to about 0.02%, more preferably about 0.01 % to about 0.02% and most
preferably about
0.01% to 0.02% of one or more fluorinated surfactants. One such surfactant
comprises about
0.06% Fluorad FC 171, about 0.04% Fluorad FC 430 and about I.0% Triton DF-I6
or Turkey
Red (Acrysol 75). Anotl2er preferred formulation comprises about 0.5%
sulfonated surfactant
(BioSoft N-300) about 0.03% Fluorad FC 171 and about 0.02% Fluorad FC 430. In
still
another particularly preferred embodiment for use on painted automobile
surfaces, the
surfactant is a combination of a sulfonated surfactant (e.g. Stephan BioSoft
N300) and a non-
ionic surfactant (e.g. an oleyl alcohol ethoxylate e.g., Rhodasurf DA630).
V. Thickeners.
Where substantial film build is desired the coating compositions of this
invention can additionally include one or more thickeners. The thickener may
be utilized to
regulate the viscosity and hlm thickness of the protective coating
composition. Thickeners
are typically known to render the composition thicker so that it can be more
easily applied
to a vertical work surface. Thickeners also known to prevent the undesirable
phenomenon
of "sagging" in which the coating becomes thinner near the top of a vertical
work surface.
It was a surprising discovery, however, that thickeners, offer previously
unsuspected advantages in the formulation of polysaccharide-based protective
coatings for
paint overspray (masking coatings). In particular, it was a discovery of this
invention that
thickeners dramatically increase the resistance of the dry film to incidental
contact with
moisture. Without tluckeners, when the polysaccharide-based film was subj
ected to
incidental moisture, (e.g. dew/condensation when the coated automobile is
stored outside
overnight, incidental condensation on very humid days, incidental
splash/misting from
washing operations, etc.), the moisture would tend to leach the plasticizer
out of the coating.
This would cause voids, sagging, and localized surface crazing, cracking, or
local film
removal resulting in paint bleed through.
Without being bound to a particular theory, it is believed that incorporation
of a thickener into the paint film results in local swelling of the thickener
where the
moisture contacts the film. The thickening tends to hold the film in place
preventing film
wash-down and blocking plasticizer leaching. Thus preferred thickeners for use
in this
invention include thickeners that thicken in response to water.
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In addition, thickeners add some film-forming capability and thereby
reinforce the film, and eliminate film cracking.
Preferred thickeners are compatible with water-based solutions and include,
but are not limited to, gums (e.g. xanthan gum) kelgin,
carboxymethylcellulose,
hydroxymethyl cellulose, methylcellulose, etc. Acrylic thickeners selected for
low water
sensitivity (e.g., Carbopol~ EP1) are also suitable, as are associative
thickeners. Alkali-
swellable acrylic emulsion thickeners capable of imparting shear-thinning
characteristics
(e.g., Carbopol~ EP1 ) may also be used this invention.
Particularly preferred thickeners for use in this invention include, but are
not
limited to crosslinked acrylate copolymers (e.g. B.F. Goodrich EP-1),
crosslinked
polyacrylic acid (e.g. B.F. Goodrich EZ-1, EDT2691), polyacrylic acid (e.g.
B.F. Goodrich
K-702), polynethacrylic acid, ethylene-acrylic acid copolymers (e.g. Morton
4983), styrene
acrylic acid copolymers, acrylic ester copolymers with acrylic acid or
methylacrylic (e.g.
Rohm and Hass ASE 75), all of which are, in preferred embodiments,
neutralized. Also
included are algin (e.g. Nutrasweet Kelzane), carboxymethyl cellulose,
carboxyethylcellulose, hydroxypropylcellulose, methocel, gum arabic, and the
like.
In certain embodiments, the thickeners) may be present at about 0.1 to 3
percent, more preferably at about 0.2 percent to about 1 percent, and most
preferably at
about 0.25 percent, by weight, of the composition.
However, in particularly preferred embodiments, the thickenex(s) range from
about 0.1 to about 30 weight percent, preferably from about 1 to about 20
weight percent,
more preferably from about 1 to about 15 weight percent, and most preferably
from about 1
or 2 to about 5 ox 10 weight percent of the masking material.
VI. pH Adjustment.
Preferred embodiments may also include components to adjust pH. Means
of adjusting pH are well known to those of skill in the art. In particular,
where the
composition is to be used as a masking composition on an automotive finish, it
is often
desirable to adjust the composition to a basic pH of about 8 to about 9. This
may be
accomplished by the addition of one of a number of water soluble bases well
known to
those of skill in the art. These include, but are not limited to sodium
hydroxide, sodium
bicarbonate and amine bases such as pyridine and ethylamine and ammonia. In
one
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particularly preferred embodiment, the pH of the coating composition is
adjusted to a
slightly basic pH (e.g. pH ~ 8.0).
VII. Preservatives.
The constituents of the coating compositions of this invention are largely
organic compounds that will readily support the growth of microorganisms such
as
microbes, fungi, and the like. Thus, in one embodiment, to increase storage
life, it is
desired to include a preservative. The term "preservative", as used herein, is
intended to
designate a substance showing antimicrobial properties, in particular
bactericidal properties
and preferably also antifungal properties. Preservatives are well known to
those of shill in
the art and include, but are not limited to anti-bacterial agents, anti-fungal
agents,
bacteriostatic agents, fungistatic agents, and enzyme inhibitors. Suitable
preservatives
include, but are not limited to benzoic acid, sorbic acid or the salts
thereof, thimerosal (or
merthiolate), phenyl mercuric acetate, phenyl mercuric nitrate, detergents
(e.g.
benzalkonium chloride), and sodium azide. Preferred preservatives are
relatively or
completely non-toxic to higher animals (e.g. mammals) and, thus, preservatives
commonly
used in foodstuffs and medical products are suitable. Such preservatives
include, but are
not limited to ethyl alcohol, chlorhexidine gluconate, sorbic and benzoic acid
and their salts,
and the like. Other preferred preservatives include Kathon LX (Rohm Haas,
Tnc.) and BTC
2125 (Stephan Chemical Co., Inc.).
VIII. Other preferred formulations.
In another preferred embodiment, the mashing compositions of the present
invention may include an aliphatic polyol such as polyvinyl alcohol in
addition to the dextrin.
When present a polyvinyl alcohol comprises from about 2 percent to about 15
percent, more
preferably from about 5 percent to about 12 percent and most preferably about
10 percent, by
weight, of the maslcing composition. One particularly preferred aliphatic
polyol is DuPont
Corporation's Elvanol 5105 having a molecular weight of about 15,000 to about
27,000
daltons. The aliphatic polyol component may iilclude two different polyols
having different
molecular weight ranges. For example, DuPont Corporation's Elvanol 5105
(15,000 to 27,000
daltons) and Elvanol 5042 (70,000 to 100,000 daltons) can be used together in
some
formulations.
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It has been found that for general purposes, a superior masking material
includes dextrin, a plasticizes, a surfactant and water. According to
preferred embodiments,
the composition includes about 10 to about 50 percent dextrin, about 5 to
about 50 percent
plasticizes and not over 2 percent total surfactant. The surfactant may
comprise up to about
0.05 weight percent fluorinated surfactant.
Thus, one particularly preferred embodiment, particularly well suited to
application to walls comprises about 10% tapioca dextrin, about 3% of a 70%
sorbitol solution,
about 6% sucrose, about 3% glycerin, about 0.5% sulfonated surfactant, about
0.03% Fluorad
FC 171, about 0.02% Fluorad FC430, about 0.25% xanthan gum, and about SO ppm
kathon lx
preservative.
Another embodiment well suited to application to walls comprises about 15%
tapioca dextrin, about 6% of a 70% sorbitol solution, about 2% sulfonated
surfactant, about
0.5% keltone thickener, and about 50 ppm kathon lx preservative.
An embodiment well suited for application to floors comprises about 30%
maltodextrin, about 6% of a 70% solution of sorbitol, about 6% glycerin, about
1% of a
sulfonated surfactant, about 0.005% triethanolamine, and about 50 ppm kathon
lx preservative.
Another preferred embodiment includes about 33 percent dextrin, about 7
percent plasticizes, and about 1.01 percent surfactant comprising about 0.01
percent fluorinated
surfactant. The plasticizes may be urea or urea in combination with glycerine
or a glycerine
derivative such as glycerine monostearate or glycerine monooleate.
In still another preferred embodiment the coating composition may include
about 40% dextrin and about 0.2 percent surfactant (e.g. Triton CF-10 or
Triton X-100 by
Rohm and Haas), plasticizes, and the remainder water. Thus one particularly
preferred
embodiment includes about 40 percent dextrin, 8 percent urea, 2 percent of a
10 percent (w/v)
aqueous solution of surfactant (e.g. Triton CF-10), and 50% water. In another
preferred
embodiment, the 8 percent urea or the preceding embodiment is substituted with
a
combination of urea and glycerine comprising about 2 percent (of the total
composition)
glycerine and S percent (of the total composition) urea. In yet another
embodiment, the 8
percent of urea may be replaced with about 2 percent glycerine and the water
may be increased
to about 56 percent of the total composition. Yet another embodiment,
particularly suitable for
force drying, includes about 40 percent dextrin, about 20 percent urea, about
2 percent of a 10
percent (w/v) solution of surfactant (e.g. Triton X-100), and about 38 percent
water.
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Finally, one preferred embodiment, including an aliphatic polyol includes
about 20 percent dextrin, about 10 percent polyvinyl alcohol (e.g. Elvanol
5105), about 3
percent glycerine, about 2 percent of a 10 percent (w/v) of a surfactant (e.g.
Triton CF-10)
and about 65 percent, by weight, water.
The mask composition is an aqueous solution and therefore includes a
substantial amount of water before drying. A variety of other materials may
also be included
in the coatings to confer specific additional properties. Thus, for example,
the coating
compositions may additionally include dyes or colorants, antioxidants or
corrosion inhibitors,
ultra-violet inhibitors, flash rust inhibitors and the like. Preferred
embodiments may include
foam reduction or foam control agents such as FoamMaker~, Bubble Brealcer~,
and l and 2
octanol. Antistatic compounds (preferably water soluble antistatics such as
Larostat 264A
made by Mazer Chemicals) may be added in preferred embodiments prevent dust
from being
drawn to the surface. Preferred embodiments may also include sequesterants
(typically less
than 1%).
IX. Coating Preparation.
The coating solutions are made by conventional means which typically
comprise mixing the components of the masking material at substantially
atmospheric
pressure, so as to form a homogeneous solution. Heat may be applied to speed
preparation
of the coating solution. After formation of a homogeneous solution, the pH may
be adjusted
as discussed above. In a particularly preferred embodiment, the pH is adjusted
to pH 8-9 by
the addition of ammonia or other pH adjusting reagents.
The coating compositions are conveniently formulated as aqueous (water-
based) solutions or emulsions. The aqueous formulation generally lacks toxic
solvents and
is therefore relatively easy to handle and work with and is readily disposed
of without
adverse environmental impact. Thus, it is generally desirable to avoid the
inclusion of any
reagents (e.g. oil, organic solvents, etc.) that impose difficulties in
handling and/or disposal.
Preferred coating compositions are therefore aqueous compositions
substantially or
completely oil free and free of organic solvents.
X. Coating Application.
The coating (masking) material is applied by one of a variety of techniques
known to those of shill in the art. These include painting, dipping, spraying,
reverse roller
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coating, and the use of doctor bars. Particularly preferred techniques include
brushing and
spraying of the material. In one preferred embodiment the surface to be
protected is blown
dry of dust and debris. In some cases, additional water may be added for
easier application,
such as a 10% dilution. Thereafter, the masking material is applied with a
pressure pot
sprayer, preferably first in a thin mist and, thereafter, in a flow coat or
thicker substantially
continuous film. For some applications, the mist coat will not be necessary.
The mask
material is sprayed primarily on the surface to be protected, although
overspray will not
pose significant problems since any overspray may be readily removed with, for
example, a
wet towel or sponge.
In preferred embodiments, the resulting masking coating is applied in a wet
coating in a thickness ranging from about 1 to about 10 mils, more preferably
ranging from
about 1 to about 4 mils, and most preferably ranging from about 1 to about 2
mils. This wet
coating then dries to form a continuous dry coating ranging from about 0.5 to
about 5, more
preferably from about 0.5 to about 2 and most preferably from about 0.5 to
about 1 mil in
thickness.
The masking material is typically permitted to dry at atmospheric temperatures
and pressures. For a 1 to 2 mil wet thickness coating, such drying will take
about 10 minutes
at 70°F and about 50% humidity.
Alternatively, the masking composition may be force-dried. Force drying may
be accomplished by means well lrnown to those of skill in the art. These
include, but are not
limited to the application of heat (e.g. radiant heating, oven baking, or hot
air blowers), the
reduction of air humidity, air movement or any combination of these means.
Under forced
drying conditions at about 150°F and about 50% humidity, the same
coatings will dry in about
2 minutes.
After drying of the masking composition, the remaining unprotected surface is
then painted or otherwise coated without fear of overspray on the portions of
the surface
protected by the masking material. If the processing operation includes
painting, the paint
applied to the surface and allowed to thoroughly dry. Such drying times will
vary radically
depending upon the particular type of paint utilized.
After drying of the paint, the masking material is removed from the protected
surface. Such removal operations may include, for example, peeling or scraping
of the
material off of the protected surface. However, it is most preferred that the
masking
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composition be removed by normal washing with water. Pressure washing with
water may
be desired in some instances. The material will be removed readily since it is
easily
miscible or soluble in water.
One of skill in the art will readily appreciate that the steps of applying and
drying the masking composition, applying and drying the paint or other
subsequent coating,
and removing the masking coating may be easily set up for mass production, as
in an
assembly line.
XI. Stain removal.
It has been observed that a number of masking films, when used on painted
automobile surfaces, introduce stains into the underlying paint finsh. It was
a discovery of
this invention that such stains are the result of water migration from the
mashing material
into the underlying automotive paint. The masking film thereby locally
hydrates the paint
surface causing Iocal swelling and resulting discoloration or other
patterning. It was a
discovery of this invention that such discoloration can be readily eliminated
by heating the
automobile surface. This is easily accomplished with a heat gun, radiant
heater, or by re-
baking the automobile.
Thus, in one embodiment this invention provides methods of eliminating
staining of a painted automobile surface caused by a water soluble protective
film. The
methods involve exposing the surface of the automobile to a heat source (e.g.
of sufficient
temperature and duration to remove the discoloration, e.g. dehydrate the paint
surface).
Heat can be applied according to any of a variety of methods including, but
not limited to
the use of a heat lamp, heat gun, or baking of the entire surface.
EXAMPLES
The following examples are intended to illustrate the present invention and
are
not intended to limit the scope of the invention in any way.
Example 1
To produce the various surface protective coatings, designated coating 1
through coating 4, dextrin, a plasticizer, a surfactant and water were
combined in the
amounts shown in Table 1. The components were combined at room temperature and
at
atmospheric pressure by slow stirring to form the various surface protective
coating
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compositions shown in Table 1. The homogeneous coating compositions were then
adjusted to pH 9 by the addition of ammonia
Table 1. Composition of four dextrin-based masking compositions.
Weight Percent
Ingredient Coating Coating Coating Coating 4
1 2 3
Dextrin 40 40 40 40
Amizo 1895
Urea 8 ---- 6 20
Adrich 208884
Glycerine ---- 2 2 ----
96% USP grade, Dow
Chemical
Triton CF-10 0.2 0.2 0.2 ----
Triton X-100 ---- ---- ---- 0.2
Deionized Water 51.8 57.8 51.8 39.8
Weight percent refers
to weight percent of
the total wet composition
accounted for by the
active ingredient.
The coatings were each applied, by spraying, to an automotive body panel
test surface thereby masking a portion of the test surface. The coatings were
then either air
dried or force-dried by heating.
The masked test panel was then sprayed with an automotive body paint and
allowed to dry. The coating compositions were then removed from the masked
portion of
the panel by simply washing the panel with water.
The coatings generally provided uniform wetting of the test surface. They
dried rapidly, typically a 1 mil layer drying in about 21 minutes at ambient
temperature
(approximately 60°F and 50% humidity).
The coatings were easily removed by the application of pressurized water
and the masked regions showed little or no penetration by the paint.
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Example 2
The components illustrated in Table 2 are combined, in the amounts shown,
at room temperature and at atmospheric pressure by slow stirring to form a
surface
protective coating composition. Again, ammonia is added to adjust the pH to pH
9.
Table 2. Composition of a dextrin/polyvinyl alcohol based masking composition.
Ingredient Weight Percent*
Dextrin 20
Amaizo 5985
Elvanol 5105 10
Glycerin 3
Triton CF-10 0.2
Deionized Water 66.8
*Weight percent refers to weight percent of the total composition accounted
for by the
active ingredient.
The composition is applied to a test panel and allowed to dry as described in
Example 1. The test panel is then painted and allowed to dry. The masking
composition is
then washed off of the panel using water to reveal the masked surface.
Examule 3
Coatings were also prepared using a low viscosity dextrin having a viscosity
ranging from about 95 to about 100 centipoise in an aqueous solution
comprising about
50% solids. The coating were prepared containing the percentages of dextrin,
plasticizer
and surfactants as shown in Table 3. Once a homogeneous solution was obtained,
the pH
was adjusted to 9 by the addition of ammoiua.
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Table 3. Composition of various low viscosity dextrin compositions.
Weight Percent
Ingredient Coating 1 . Coating 2 Coating 3 Coating 4
Low Viscosity 33 33 33 33
Dextrin
Amaizo 2686N
Urea 7 7 5.6-5.95 5.6-5.95
Aldrich 208884
Glycerine -- -- 1.05-1.4 1.05-1.4
monosterate or
glycerine monoleate
DF 16 1 -- - --
Turkey Red -- 1 1 1
Actrasol C-75
FC171 0.06 0.06 0.06 0.06
3M
FC430 0.04 0.04 0.04 0.04
3M
Deionized Water 58.9 58.9 58.9 58.9
*Weight percent refers composition
to weight percent of accounted
the total
for by the active ingredient.
The coatings were applied to test panels by spraying. The coatings generally
provided uniform wetting of the test surface. They dried rapidly, typically a
10 mil layer
drying in about 21 minutes at ambient temperature (approximately 60°F
and 50%
humidity).
The coatings were easily removed by the application of pressurized water and
the mashed regions showed little or no penetration by the paint.
Example 4
To compare a dextrin-based coating of the present invention with the
commercially available polyvinyl alcohol coating SlimePlus~, each half of a
test panel
bearing an automotive acrylic finish, was respectively coated with SlimePlus~
or with a
dextrin coating comprising the components illustrated in Table 3.
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Table 4. Test composition for comparison with SlimePlus~
Ingredient Weight Percent*
Dextrin 33%
Amaizo 1895
Urea 7%
Aldrich 208884
DF-16 surfactant 1%
Union Carbide
FC-171 0.06%
3M
FC-430 0.04%
3M
Deionized Water 58.9%
*Weight percent refers to weight percent of the total composition (wet
formulation) accounted for by the active ingredient.
**After the components listed above were combined to form a
heterogeneous solution, the pH was adjusted to pH 9 by the addition of
axmnonia.
The two sides of the panel were simultaneously coated; one with the
SlimePlusTM composition and the other with the dextrin composition. The wet
coatings
were applied in a thickness sufficient to provide a uniform continuous dry
film about 1 mil
thick. This required about a 10 mils wet coating of SlimePlusTM, while only a
2-3 mil wet
coating of the dextrin compound.
Under ambient conditions (about 62°F and 60% humidity), the
dextrin
composition dried in about 21 minutes, wlule the SlimePlusTM coating took well
over an hour
to dry. Both coatings provided a continuous substantially free of pinholes and
dry to the touch.
The dextrin based coating, however, eliminated a whitening of black paint
observed with SlimePlusTM. Without being bound to a particular theory, it is
believed that
SlimePlus~ passes through a gel phase when drying. This gel phase tends to
hydrate the
automotive paint coating on the underlying surface producing a temporary local
whitening.
The dextrin coatings of the present invention eliminate paint hydration and
the resulting
whitening thereby requiring less post rinse-off cleaning of the underlying
(protected)
surface.
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Example 5
Coatings were also formulated using either a tapioca dextrin (for coatings
optimized for application to paint booth walls or a maltodextrin (for coatings
optimized for
application to floors) as shown in Table 5. The coatings were formulated as a
homogeneous
aqueous solution. When applied to paint booth walls, the "crystal booth"
coatings offered
good protection, did not discolor through repeated drying cycles, and were
easily removed
by washing. The "clean room" coating, when applied to the floor showed good
build,
provided a slightly tacky finish that helped suppress dust, and was readily
removed by
washing.
Table 5. Formulation of coating compositions optimized for application to
paint booth
walls (crystal booth 1 and crystal booth 2) or to paint booth floors (clean
room).
Preferred Embodiments
Components Range Crystal Crystal Clean
Booth 1 Booth 2 Room
Film Former Dextrin: 2%-50%
Crystal Gum 10% 15%
(Tapioca Dextrin)
(I~4484, National
Starch)
Star-DRI 180 30%
(maltose dextrin)
Star-Dri 180
or Star-Dri100, 1,
5, 200
Plasticizer Sorbitol 0-16% 3% 6% 6%
(70% Solution)
Sugar (sucrose) 0-16 6%
Glycerin 0-16 3% 6%
Thickener Xanthan Gum 0-1.0% 0.25%
(Kelzan)
I~eltone 0.5%
or carboxymethyl
cellulose,
hydroxymethylcellulose,
polyethylene oxide etc.
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Surfactant Sulfonated 0.1-2.0%
Biosoft N-300 0.1-2.0% 0.5% 2% 1%
(Stepan Chemical
Co.)
or BioSoft D40,
Sulfochem-TLS or
Sulfochem-ALS
Fluorinated
Fluorad FC 171 0-0.6% 0.03%
Fluorad FC 430 0-0.4% 0.02%
(3M Corp.)
pH
adjustment triethanolamine 0.01-1.0 0.5
85% or potassium carbonate
solution or sodium carbonate
Preservative
Kathon Lx 10 ppm- 50 ppm 50 pprn 50 ppm
100 nnm
Examule 6
Coatings were also formulated using a thickener/film former combination.
either a tapioca dextrin (for coatings optimized for application to paint
booth walls or a
maltodextrin (for coatings optimized for application to floors) as shown in
Table 5. The
coatings were formulated as a homogeneous aqueous solution. When applied to
paint booth
walls, the "crystal booth" coatings offered good protection, did not discolor
through
repeated drying cycles, and were easily removed by washing. The "clean room"
coating,
when applied to the floor showed good build, provided a slightly tacky finish
that helped
suppress dust, and was readily removed by washing.
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Table 5. Formulation of coating compositions optimized for application to
paint booth
walls (crystal booth 1 and crystal booth 2) or to paint booth floors (clean
room).
Preferred
Embodiments
Components
Range Crystal Crystal Clear-
Booth Booth Room
1 2
Film FormerDextrin: ~ 2%-50%
Crystal Gum 10% 15% 30%
(Tapioca Dextrin)
(K4484, National
Starch)
Star-DRI 180
(maltose dextrin)
Star-Dri 180
or Star-Dri100,
1,
5, 200
PlasticizerSorbitol 0-16% 3% 6% 6%
(70% Solution)
Sugar (sucrose) 0-16 6%
Glycerin 0-16 3% 6%
Thickener Xanthan Gum 0-1.0% 0.25%
(Kelzan)
Keltone 0. 5
or carboxymethyl
cellulose,
hydroxymethylcellulose,
polyethylene oxide
etc.
SurfactantSulfonated 0.1-2.0%
Biosoft N-300 0.1-2.0%0.5% 2% 1%
(Stepan Chemical
Co.)
or BioSoft D40,
Sulfochem-TLS or
Sulfochem-ALS
Fluorinated
Fluorad FC 17I 0-0.6% 0.03%
Fluorad FC 430 0-0.4% 0.02%
(3M Corp.)
pH
adjustment triethanolamine 0.01-1.0 0.5
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85% or potassium carbonate
solution or sodium carbonate
Preservative
Kathon Lx 10 ppm- 50 ppm 50 ppm 50 ppm
100 npm
Example 7
Coatings were also formulated using thickener/filrn former combinations
(see, e.g. Table 6 for a preferred formulation) using a dextrin film former, a
sorbitol
plasticizes, and a thickener. The coatings were formulated as a homogeneous
aqueous
solution. When applied to automobile surfaces, the coatings offered good
protection, did
not discolor through repeated drying cycles, and were easily removed by
washing.
Moreover, on vehicles stored overnight to permit dew formation on the coated
surface or
with incidental moisture, the coatings did not leach plasticizes remained
intact and provided
highly effective protection from paint.
Table 6. Formulation of polysaccharide/thickener coating compositions
optimized for
application to painted automobile surfaces subjected_ to incidental moisture.
Weight Percent
Components Range Preferred Optimized coating
Film Former Polysaccharide 2%-90% 5%-30% 7%
e.g. dextrin, starch, (Staley Stadex 140
cellulose derivatives, Dextrin)
etc.
Plasticizes e.g. sorbitol or other 3%-16% 7%
0.8%-30%
sugars, urea, glycerin (sorbitol 70%
solution)
Thickener e.g., Goodrich EP-1, 0.1%-30%1%-10% 3.5%
Goodrich EZ-l, (Goodrich EP-1)
Goodrich K-702,
Goodrich EDT2691,
Nutrasweet Kelzane
(algin),
carboxymethylcellulose
Morton 4983,
methocel, gum Arabic,
Rohm and Haas ASC
75
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Surfactant Total: 0.01-10.0%0.1-5%
Sulfonated 0.01-10.0%0.1-5% 0.41%
(Stephan BioSoft
N300)
Non-ionic 0.01-10.0%0.1-5% 0.25%
(Rhodasurf DA630)
pH e.g., sodimn hydroxide, pH 7.5-11 pH 8-10 0.180
adjustment potassium carbonate, pH = 9-9.5
sodium carbonate, sodium hydroxide
triethanolamine
Preservative e.g., Kathon Lx 0.0001 to 0.001% - 0.005%
0.1 % 0.1% Kathon Lx-14
Water e.g. filtered water, remainder
distilled water
deionized water
Examine 8
Coatings were also formulated using thickener/film former combinations
(see, e.g. Table 7 for a particularly preferred formulation) using a dextrin
film former, a
sorbitol plasticizer, and a thickener. The coatings were formulated as a
homogeneous
aqueous solution. When applied to automobile surfaces, the coatings offered
good
protection, did not discolor through repeated drying cycles, and were easily
removed by
washing. Moreover, on vehicles stored overnight to permit dew formation on the
coated
surface or with incidental moisture, the coatings did not leach plasticizer
remained intact
and provided highly effective protection from paint.
Tabne 7. Formulation of polysaccharide/thickener coating compositions
optimized for
application to painted automobile surfaces subjected to incidental moisture.
Weight Percent of Final Composition
Before Drying.
Components Preferred Optimized coating
range
Film Former Polysaccharide 1%-10% 5%
e.g. dextrin, starch, (Staley Stadex 140 Dextrin)
cellulose derivatives, etc.
Plasticizer e.g. sorbitol or other 1%-I6% 3.4%
sugars, urea, glycerin
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Thickener e.g., Goodrich EP-1, 1 %-10% 0.72%
Goodrich EZ-1, Goodrich (Goodrich EP-1)
K-702, Goodrich
EDT2691,
Nutrasweet Kelzane
(algin), ,
carboxymethylcellulose,
Morton 4983, methocel,
gum Arabic, Rohm and
Haas ASC 75
Surfactant Total: 0.1-5%
Sulfonated 0-5%
Non-ionic 0-5% 0.5%
(Rhodasurf DA630)
pH e.g., sodium hydroxide, pH 8-10 0.134
adjustment potassium carbonate, pH ~ 9-9.5
sodium carbonate, sodium hydroxide
triethanolamine
Preservative e.g., Kathon Lx 0.001% - 0.005%
0.1 % Kathon Lx-14
Water e.g. filtered water, remainder
distilled water
deionized water
The above descriptions are illustrative and not restrictive. Many variations
of the invention will become apparent to those of skill in the art upon review
of this
disclosure. Merely by way of example, while the invention is illustrated with
regard to
particular brands of materials used in the mask, the invention is not so
limited. The scope of
the invention should, therefore, be determined not with reference to the above
description,
but instead should be determined with reference to the appended claims along
with their full
scope of equivalents.
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