Protective coating and method of using such coating

A vehicle masking material and method of use. The masking material in one embodiment includes polyvinyl alcohol, ethyl alcohol, glycerine or triethylene glycol, a surfactant, and water. The masking material is applied to a surface which is to be protected from paint overspray or other mechanical process, allowed to dry, and paint is applied. After drying of the paint, the masking material is removed by peeling or water washing.

BACKGROUND OF THE INVENTION 
The present invention relates to the field of protective coatings to be 
used during mechanical processing operations of vehicles or buildings. 
More specifically, in one embodiment the invention provides an improved 
method and composition for masking selected portions of a vehicle from 
paint. 
It is well known that painting operations often require masking of certain 
portions of the vehicle or building to prevent overspray. For example, it 
is often necessary to mask trim and windows on a 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. It is also well known that many surfaces are 
susceptible to marring and scratching during mechanical processing 
operations on proximate surfaces. For example, welding and grinding can 
have deleterious effects on surrounding surfaces. 
In practice, masking 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 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 which are desired to be protected. 
Solutions have been proposed to the problem of protecting surfaces during 
mechanical 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. This causes 
particular problems because environmental controls of solvents are 
becoming 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 composition is needed. 
SUMMARY OF THE INVENTION 
An improved masking 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, 
building, or other work surface to be protected during a "mechanical 
processing operation". Such operations include, for example, painting, 
grinding, welding, and etching. These steps may be performed, for example, 
during an assembly line production of a vehicle. 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 mechanical processing could reach an 
underlying surface. The masking material is, in one specific embodiment, a 
composition of water, an aliphatic polyol, alcohol, and a surfactant. In a 
different embodiment the masking material includes water, a plasticizer 
(such as glycerine, triethylene glycol or polyethylene glycol), an 
aliphatic polyol, alcohol and surfactant. The masking material will dry 
quickly, and be readily removable with water after use. Further, the 
material is relatively harmless from an environmental point of view. 
A further understanding of the nature and advantages of the inventions 
herein may be realized by reference to the remaining portions of the 
specification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention provides an improved method and composition for 
protecting a vehicle or other work surface to be painted or mechanically 
processed. For example, certain regions of an automobile may be masked in 
accordance with the present invention to protect those regions from paint 
overspray in a painting booth. The method and composition produces a film 
which adheres well to a surface to be protected, with few or no pinholes. 
Further, the material can be removed easily from the surface to be 
protected after use with a water wash, or by peeling, or by combinations 
of the two. 
More generally, the present invention provides an improved method and 
composition for protecting selected surfaces during selected mechanical 
processing operations such as welding or grinding, as well as painting. 
The adherent film of the present invention protects the selected surface 
from marring, scratching or other deleterious effects associated with 
mechanical processing. The mechanical processing steps might be 
encountered, for example, during assembly or repair of vehicles, or during 
construction or renovation of buildings. The present invention can be 
employed with particular advantage during fabrication of vehicles or other 
products on an assembly line. An assembly line production typically 
employs a series of steps including, for example, grinding, welding, and 
painting. Each of these operations can advantageously employ the masking 
composition and method of the present invention. 
One embodiment includes water, an aliphatic polyol, alcohol, and a 
surfactant. According to preferred embodiments, the composition includes 
at least about 1% polyvinyl alcohol by weight. Preferred compositions 
include between 1 and 30% aliphatic polyol such as polyvinyl alcohol, with 
most preferred compositions of about 5 to 20% polyvinyl alcohol, and one 
specific embodiment including about 8% polyvinyl alcohol. The aliphatic 
polyol component may include 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. 
For some applications, it will be necessary to provide a "thicker" or more 
viscous protecting material formulation. For instance, in painting train 
boxcars, a thicker formulation is desirable for protecting the wheels and 
couplings from overspray. The wheels and couplings of boxcars must be 
periodically inspected for cracks by techniques which are well known in 
the art. To avoid obscuring these cracks, the protecting material should 
be thick enough that it does not penetrate any existing cracks. For such 
applications, the protecting material formulation may be made thicker by a 
variety of means which are well known in the art. For example, the 
concentration of a high molecular weight polyvinyl alcohol can be 
increased. Preferably, the masking material will have a viscosity of about 
50 to 1000 centipoise, and preferably about 200 centipoise. 
It has been found that for general purposes a superior masking material 
includes water, an aliphatic polyol (preferably a partially hydrolyzed 
polyvinyl alcohol having a molecular weight from about 15,000 to about 
100,000), a plasticizer, alcohol, and a surfactant. According to preferred 
embodiments, the composition includes at least about 0.1% by weight of a 
plasticizer such as glycerine. Preferred compositions include between 0.5 
and 7% glycerine, and one specific embodiment including about 1% 
glycerine. 
An alternative preferred embodiment includes water, triethylene glycol, an 
aliphatic polyol, alcohol surfactants. According to this embodiment, the 
composition includes as a plasticizer at least about 0.1% by weight 
triethylene glycol. More preferably, the triethylene glycol content ranges 
from 0.5% to 5%, and in one specific embodiment includes about 2% 
triethylene glycol. For some applications, a polyethylene glycol having a 
molecular weight of between about 100 and 1,000 may be substituted as a 
plasticizer for the triethylene glycol. 
The masking material will include a lower molecular weight alcohol. 
Preferred alcohols for the composition include methyl alcohol, ethyl 
alcohol, and 2-propyl alcohol. A most preferred alcohol is ethyl alcohol. 
For many applications, the percentage of alcohol utilized is preferably 
less than about 25% by weight (based on 190-proof alcohol), with 
compositions having less than 20% alcohol most preferred. When ethyl 
alcohol is utilized, most preferred compositions include between 10 to 20% 
alcohol with about 10 to 15% preferred, and 12 to 13% most preferred. 
However, when thicker formulations are desired, a higher concentration of 
alcohol may be used to speed the drying process. Up to about 40% alcohol 
can be used for some applications. When methyl or propyl (such as 
isopropyl or 2-propyl) alcohol is utilized as a denaturant, compositions 
with less than 1.0% by weight denaturant alcohol are preferred, and 
compositions of between 0.5 and 1.0% are most preferred. 
The masking material also includes a surfactant. The surfactant is, in one 
embodiment, a nonionic biodegradable surfactant such as an acetylenic 
diol. In preferred embodiments, the invention includes an alkyl aryl 
surfactant (such as Triton CF-10 and CF-12), a polyethoxy adduct, or a 
modified (poly) ethoxylate (such as Triton DF-12 and DF-16). Other 
surfactants include nonylphenoxypolyethanol (such as IGE CO-660 made by 
GAF), polyoxyalkylene glycol (such as Macol 18 and 19 made by Mazer 
Chemicals), acetylenic diol-based surfactants (such as Surfynol 104A made 
by Air Products), and the like. Preferred compositions include up to 10% 
surfactant. Most preferred compositions include less than 5% by weight 
surfactant and more preferably less than 1% surfactant, with one specific 
implementation including about 0.3% surfactant. 
The mask also includes a substantial amount of water, such as deionized 
water having a resistivity of about 18 megaohm-cm. In one embodiment of 
the invention, the balance of the mask is composed of water, although a 
variety of other materials may also be included such as dyes, odorants, 
and the like. 
Antistatic compounds are added in preferred embodiments to reduce static 
build-up. This prevents static from being drawn to the vehicle in 
question. Antistatics (such as Lowstat HTS-905 made by Mazer Chemicals) 
are provided in some embodiments, preferably water soluble. Sequesterants 
are also added in some embodiments (less than 1%) such as citric acid for 
a pH of 5-6, glycolic, sodium citrate or the like. Sequesterants will 
reduce spotting. 
The masking material is made by conventional means, typically including the 
steps of gently mixing the components of the masking material at 
substantially atmospheric pressure, so as to form a substantially 
homogeneous mixture. The components are preferably heated during mixing 
such as from 180.degree. F. to 200.degree. F., excluding the alcohols, 
which are added after mixing the remaining components. 
The masking material is applied by one of a variety of techniques. 
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 from about 0.5 to 4 mils 
thick, preferably about 1.5 to 2.5 mils thick, with a preferred thickness 
of about 2 mils. 
The masking material is then permitted to dry, normally at atmospheric 
temperatures and pressures. Such drying will take about 10 to 30 minutes 
in typical applications (at room temperature and 30% humidity). 
Significantly longer drying times are needed at 50.degree. F. For such 
lower temperatures, additional ethanol may be provided in a separate 
container to increase the ethanol content by about 10% by weight. The 
surface is then painted or otherwise mechanically processed without fear 
of overspray on the portions of the surface protected by the masking 
material. Baking (at, e.g., 130.degree. F.) may be desirable in some 
embodiments. 
If the processing operation includes painting, the paint is first 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 of the material off of the 
protected surface. In alternative embodiments the mask is removed by 
normal washing with water, but 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. 
EXAMPLES 
The following examples are offered as illustrations of the invention: 
1. Alcohol Content 
Four samples of masking material were made including 6 to 9% polyvinyl 
alcohol, about 0.3% surfactant, and water. Varying amounts and types of 
alcohols were utilized. Alcohols included ethanol, isopropanol, and 
methanol. Automotive surfaces were masked with the materials. The tests 
showed that while higher percentages of alcohol produced faster drying 
mask materials and better layout of the materials, automotive paints were 
adversely effected, resulting in dulling of the paint. Isopropyl and 
methyl alcohols were found to have the most deleterious impact on 
automotive paint. Ethyl alcohol contents of from 10 to 20% did not result 
in paint damage, while having suitable drying times (about 30 minutes, 
with the higher alcohol content samples having shorter drying times), and 
solids dispersion properties. Using methyl and propyl alcohol as 
denaturants, it was necessary to maintain the denaturant alcohol content 
below 1% of the total masking finished product to reduce paint damage to 
an acceptable level. Lower alcohol content may also be desirable to ensure 
a higher flash point material. 
2. Surfactant 
Base samples with 8% polyvinyl alcohol and ethyl alcohol contents ranging 
from 10 to 25% were prepared. Multiple surfactants were used including 
acetylenic diol-based surfactants (such as TG and PC made by Air 
Products), polyoxyalkylene glycol-based surfactant (Macol 18 and 19 made 
by Mazer Chemicals), nonylphenoxypolyethanol-based surfactant, and 
polysiloxane. 0.3% surfactant was utilized. Acetylenic diol-based 
compounds produced satisfactory results (i.e., no spotting or dulling). 
Polyoxyalkylene glycol-based materials produced the best results, but 
suffered from foaming during application. Glycol-based compounds laid out 
the best overall. 
3. Scents 
Samples were tested to determine if an odorant would be needed to overcome 
effects of the high alcohol content. It was found that scent did not 
appreciably improve the odor of the material when alcohol content was 
maintained below 20% and that the material had a pleasant smell. 
4. Defoamers 
Samples were tested with various defoamers. Samples were tested with 
polysiloxane (XFB41-58 made by Air Products), acetylenic glycol (Surfynol 
64A made by Air Products), and oil-based defoamers in an amount of less 
than 1%, and preferably 0.05%. Polysiloxane and acetylenic glycol produced 
satisfactory masking material. Oil-based defoamers left an oily residue on 
protected surfaces. Acetylenic glycol defoamer was preferred. 
5. Film Prevention 
In order to reduce residual films left by the masking materials, additional 
surfactants were tested. Alkyl aryl-based surfactants (Triton CF-10 and 
CF-12 or Perform Plus), polyethoxy adduct-based surfactants, and modified 
ethoxylate-based surfactants (such as Triton DF-12 and DF-16) were tested 
for residual film prevention. Polyethoxy adduct-based surfactants and 
modified ethoxylate-based surfactants provided reduced film retention. 
Particularly good results were obtained using Fluorad 171 and Fluorad 430 
(both made by 3M Company) in conjunction with Triton DF-16. 
According to a preferred embodiment, the masking material included the 
following components presented in a per weight basis: 
Deionized water (Megaohm-cm) 79% 
PVA, partially hydrolyzed solids, (typically 87%-89% hydrolyzed) 
Ethyl alcohol 12.5% (including methanol; 3-6%; isopropyl of the ethanol and 
1-3% of the ethanol isopropyl) 
Surfactant, Perform Plus, 0.3% 
Antistatic, less than 0.5% 
Defoamer, less than 1% 
According to a different preferred embodiment, the masking material 
included the following components presented in a per weight basis: 
Deionized water (18 ppm) 77.1% 
Triethylene glycol 2.0% 
Denatured ethyl alcohol 12.5% 
Surfactant 0.25% 
Polyvinyl alcohol (Elvanol 5042 (Dupont Corp.) 1.0% and Elvanol 5105 
(Dupont Corp.) 7.0% ) 
According to a most preferred embodiment, the masking material included the 
following components: 
Deionized Water (18 ppm) 78.1% 
Glycerine 1.0% 
Denatured Ethyl Alcohol 12.0% 
Surfactant 0.25% 
Polyvinyl Alcohol (Elvanol 5042 (Dupont Corp.) 1% and Elvanol 5105 (Dupont 
Corp.) 7%) 
A thicker masking material included the following components presented in a 
per weight basis, especially for use in train masking operations and the 
like: 
Deionized Water 49.71% 
Denatured Ethyl Alcohol (190 proof) 35.00% 
Glycerine 5.00% 
Polyvinyl Alcohol (Elvanol 5042 (DuPont Corp.) 2.66% and Elvanol 5105 
(DuPont Corp.) 7.33%) 
Surfactant 0.25% (Triton DF-16 0.20%, 3M FC 171 0.03%, and 3MFC 430 0.02%) 
Yellow Dye 0.05% 
The above description is 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 regards 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.