Sprayable coating composition

A sprayable, high solids, low-volatiles composition is provided which may be used as a coating on a variety of substrates. The sprayable filler composition comprises a first filler/glazing component formed from a mixture of a resin, a filler, a mixture of thixotropic clays, a phosphosilicate, and a first organic solvent. The coating also has a second organic solvent component as well as a second catalyst component. The coating as applied to a substrate has a thickness of up to 6 mils without sagging, running or cracking.

FIELD OF THE INVENTION 
The present invention relates to a sprayable composition, and more 
particularly, to a very high solids, low-volatiles sprayable filler 
composition which may be used as a coating on a variety of substrates. 
BACKGROUND OF THE INVENTION 
Multi-component spraying systems which are widely used in the plastics and 
marine industries. In such systems, a liquid resin and a catalyst for the 
resin are mixed together and sprayed onto a substrate such that the 
catalyst and resin react and harden on the substrate. The mixing may be 
done immediately before spraying (referred to as an internal mix system) 
or immediately after spraying (referred to an external mix system). In 
either event, such coatings are referred to as a "gel coat". For example, 
U.S. Pat. No. 4,967,956 to Mansfield discloses a "gel coat" spraying 
system which uses a resin such as an epoxy resin or a polyester resin, a 
catalyst for the resin, and spraying means which includes an airless 
liquid nozzle. Such gel coats utilize a slow curing process, and the 
coatings do not provide a sandable surface. Another disadvantage of such 
gel coatings is that application of the coatings is effected through the 
use of organic solvents to reduce viscosity. 
Because of increased environmental concerns about volatile organic 
components (VOC's), efforts have been made to reduce the amount of 
volatile materials used in such coating operations. As a result, the use 
of high solids coatings has been employed to meet VOC regulations. For 
example, White et al. U.S. Pat. No. 5,057,555 discloses a coating 
composition having a high solids content which is used as a finish for 
automobiles and trucks comprising an acrylic polymer and a catalyst. 
However, the coating cures very slowly. In addition, the composition still 
includes from 20-60% of an organic solvent and therefore has a tendency to 
run and sag when applied to vertical surfaces and can exhibit poor shelf 
and pot life. 
As an alternative to using organic solvents, Bok et al, U.S. Pat. No. 
5,171,613, teaches using a supercritical fluid as a non-polluting diluent 
in combination with a coating mixture. However, the method of spraying the 
coating requires the use of a heated spray gun to maintain the temperature 
of the coating mixture. 
It is also known through the assignee of the present application that a 
sprayable, high solids, low-volatile filler composition may be used as a 
coating on a variety of substrates including metals such as iron and 
aluminum, concrete, wood, fiberglass and polyester fillers, etc. See, for 
example, Parish et al U.S. Pat. No. 5,371,117, issued Dec. 6, 1994 which 
discloses a sprayable filler composition having a first filler/glazing 
component formed from a mixture of a resin, a filler, a mixture of 
thixotropic clays, activated fumed silica, hollow glass microspheres, and 
a ketone solvent and having a second catalyst component. It has also been 
discovered that such a composition can, in some instances, result in an 
undesirable degree of an "orange peel" effect which necessitates extensive 
sanding. 
It is also known that various fiber reinforced plastic (FRP) parts such as 
cured sheet molded compounds (SMC) can form cracks and sink marks which 
affect surface appearance. SMC is produced from unsaturated polyester or 
vinyl ester resin primarily. It is formulated with calcium carbonate 
filler, fiberglass for reinforcement, one or two catalysts, and usually an 
internal release agent like zinc stearate. The material is "B-staged" 
(thickened to a semi-solid) in long sheets which are rolled up for 
storage. When ready to mold, it is cut to mold size, placed into the mold 
which experiences clamp pressure and heat which fully cures the product in 
its final shape. Cycle times are usually 3-5 minutes depending on part 
size. After molding the "Stamped" parts usually have flashing that needs 
to be removed (usually by sanding), and/or may experience some type of 
processing like routing-out access holes, etc. This leaves raw edges or 
spots on the molded piece. When conventional paints are used, solvent can 
become trapped in these areas and subsequently "pop-out" when heated 
during normal baking processes. This creates a great deal of unusable 
parts. This phenomenon is greatly enhanced/accelerated by use of glass 
bubbles in the SMC formula to provide "low density" parts in an effort to 
reduce vehicle weight. 
Accordingly, it has been suggested that a thin coating made from a liquid 
rubber and liquid eopxy polymer be used as a primerlike coating to inhibit 
propagation of micro cracks, reduce porosity and reduce sink marks in FRP 
parts to provide a suitable smooth surface for automotive body panel 
applications that serves as a substrate for further paint applications. 
See, McGarry U.S. Pat. No. 5,358,779, issued Oct. 25, 1994. 
It is further known through the assignee of the present application that a 
sprayable, high solids, low-volatile filler composition may be used on 
molded fiber reinforced plastic (FRP) parts. See, for example, Parish, 
U.S. Pat. No. 5,549,969, issued Aug. 27, 1996 which discloses a sprayable 
filler compositing having a first filler/glazing component formed from a 
mixture of a resin, a filler, a mixture of thixotropic clays, activated 
fumed silica, a phosphosilicate, and 0-20% by weight of an organic solvent 
and having a second catalyst component. While U.S. Pat. No. 5,549,969 
discloses that a sprayable, high solids, low-volatile filler composition 
may be used on molded fiber reinforced plastic (FRP) parts, it has been 
discovered that such a composition can, in some instances, result in a 
undesirable degree of waveyness of the surface, both in depth and length 
of wave, i.e., an undesirable degree of an "orange peel" effect which 
necessitates extensive sanding/post-processing. 
Accordingly, the need remains for an improved coating for substrates which 
1) uses a minimum of low-volatile solvents; 2) which is easy to apply; 3) 
which reduces or eliminates paint "pop-out"; 4) which reduces porosity and 
sink marks; and 5) which results in a surface which is immediately 
suitable for subsequent application of top coats. 
SUMMARY OF THE INVENTION 
That need is met by the present invention. Thus, there is provided a 
sprayable filler coating composition comprising: 
a) a filler/glazing component comprising a mixture of from about 20% to 80% 
by weight of a resin selected from the group consisting of vinyl ester 
resins, and vinyl ester resins in combination with polyester resins; from 
about 2% to about 35% by weight of a sprayable filler such as talc, from 
about 0.1% to about 15% by weight of a mixture of thixotropic clays, from 
about 1-10% by weight of a phosphosilicate, from about 0-2% of an 
accelerator such as dimethyl aniline, cobalt naphthenate, copper 
napthenate, potassium hexanoate, dimethyl para-toluidine, cobalt 
neodecanate, or mixtures thereof; and from about 0% to about 20% and 
preferably from about 5-10% by weight of a first organic solvent or 
organic solvent mixture; 
b) a catalyst component which may be present in an amount of from about 
1-50% and preferably about 2-6% by weight of the total coating as applied 
(i.e., preferably the filler/glazing component comprises about 96-98% of 
the coating and the catalyst component comprises about 2-6%). The catalyst 
is preferably methyl ethyl ketone peroxide or cumyl hydrogen peroxide, 
with cumyl hydrogen peroxide being preferred. 
c) and from about 1-15% and preferably from about 5-10% by weight of a 
second organic solvent component; and 
The filler/glazing component may further include about 0-4% and preferably 
0.2-4% by weight of a coloring agent such as titanium dioxide, black iron 
oxide, acetylene black, or mixtures thereof; and from about 0-40% by 
weight of a styrene monomer. 
The filler/glazing component may further include about 0-1% fumed silica 
and 0-5% of an acrylic resin. 
This coating provides an improved coating for molded FRP parts which 
enhances the surface of the molded FRP part which 1) uses a minimum of 
low-volatile solvents; 2) which is easy to apply by most comon application 
equipment; 3) which reduces or eliminates paint "pop-out"; 4) which 
reduces porosity and sink marks; and 5) which results in a surface which 
is immediately suitable for subsequent application of top coats. The use 
of a minimum of low-volatile solvents is not only desirable for 
environmental reasons, but also provides an improved surface quality due 
to improved flow characteristics (i.e., it does not exhibit the poor 
characteristics usually associated with high solvent content coatings, 
such as poor cure times, running and sagging when applied to vertical 
surfaces and poor build capabilities). In addition, the coating of the 
present invention has a high gloss and exhibits a long-wave profile, 
thereby allowing for Class-A surface attainment. Further, although this 
coating does not require sanding, it may be sanded if additional leveling 
is required. In addition, the coating is bake temperature resistant while 
retaining its flexibility and exhibits a high level of conductivity for 
subsequent electrostatic applications of top coats. This coating, which 
functions as a primerlike coating, could replace in-mold coatings 
presently used to enhance surface appearance on molded products from 
thermosetting FRP from sheet molded compounds (SMC), bulk molding 
compounds (BMC), and thick molding compounds (TMC). Specifically, this 
invention is useful in automotive body parts, furniture, sporting goods, 
chemical processing equipment, and the like.

DETAILED DESCRIPTION OF THE INVENTION 
The sprayable filler composition of the present invention comprises a first 
filler/glazing component including a resin selected from the group 
consisting of vinyl ester resins and the combination of vinyl ester resins 
and polyester resins. Such resins provide fast curing and good adhesion. 
If higher gloss and a non-sanding product is desired, the filler/glazing 
component preferably contains from about 50-80% and more preferably about 
70-80% of a mixture of vinyl ester resins and polyesters. This allows for 
additional flow and surface leveling as well as a higher gloss and 
provides for a surface which does not need to be sanded. Such mixture is 
preferably composed of from about 40-42% vinyl ester resins by weight of 
the coating and from 30-36% polyester resins by weight of the coating. 
Suitable polyester resins are auto resin (ortho polyester) and bonding 
ortho NPG Polyester. Auto resin is available under the Reichhold trademark 
and the designation 32-266-29, which is a mixture of 36.0% Styrene and 
proprietary resin, and which has a boiling point of 295.degree. F., a 
volatile percentage of 7.2%, a vapor density heavier than air and a 
specific gravity of 1.12-1.16. Bonding ortho NPG polyester is available 
under the Reichhold trademark and the designation 33-707-00, which is a 
mixture of styrene of 39% and proprietary resin, and which has a boiling 
point of 295.degree. F., a volatile percentage of 7.8%, a vapor density 
heavier than air and a specific gravity of 1.10-1.14. 
Suitable vinyl ester resins include 8084 vinyl ester, which is a mixture of 
40-50% of a styrene monomer (CAS #000100-42-5) and the balance vinyl ester 
resin (CAS #068492-68-2), and which has a boiling point of 294.degree. F., 
a vapor pressure of 7 mmHg at 20.degree. C., a vapor density of 3.6 based 
on styrene, and a specific gravity of 1.010-1.035, and 411-35 vinyl ester, 
which is a mixture of 35-50% of a styrene monomer (CAS #000100-42-5) and 
the balance vinyl ester resin (CAS #036425-16-8), and which has a boiling 
point of 294.degree. F., a vapor pressure of 7 mmHg at 20.degree. C., a 
vapor density of 3.6 based on styrene and a specific gravity of 
1.025-1.075, both available from Dow Chemical Company of Midland, Mich. 
under the DERAKANE trademark. 
The preferred filler for the filler/glazing component of the present 
invention is talc, which allows retention of a bridging effect (i.e., the 
effect of flowing over a small area of porosity and having enough film 
integrity to resist any surface disruption (popping) upon heating) without 
contributing to surface roughness. Talc also provides thixotropic 
properties to the composition and also aids in providing sanding 
properties to the coated substrate when sanding is desired. A preferred 
talc is 609 ULTRATALC, available from Mineral Technologies, Inc. 
In addition, the filler/glazing component preferably includes about 0-40% 
and preferably about 30-40% by weight of a styrene monomer. Addition of 
styrene monomer increases the rate of polymerization and provides a lower 
viscosity which results in better atomization during spray application 
while retaining the overall reactivity of the system. However, it should 
be noted that in instances where vinyl esters alone are used as the resin, 
an encapsulated petroleum based wax may be used in place of some of the 
styrene. Suitable waxes include BYK S-740 available from Byk Chemie. 
The filler/glazing component may further include from about 0% to about 1% 
by weight activated fumed silica. Fumed silica is commercially available 
from DeGussa Company under the trade name AEROSIL 200. The fumed silica is 
preferably activated by the addition of ethylene glycol. Because fumed 
silica alters the rheology of the coating in a manner that detracts from 
surface flow, its use is preferably limited to those instances when the 
product is to be sanded. When included in the filler/glazing component, 
fumed silica provides fast viscosity, and also acts as a thixotropic 
agent. 
The filler/glazing component may further include from about 0-5% of an 
acrylic resin by weight of the filler/glazing component. Because acrylic 
resin is a saturated solvent dispersed material which is used to assist 
the sandability of the product, its use is preferably limited to those 
instances when the product is to be sanded or when the ability to do spot 
repairs is desired. 
The thixotropic clays suitable for use in the filler/glazing component of 
the present invention include prewet and dry organo clays. A suitable 
prewet clay is available from Rheox, Inc. under the trade name MPA-60-x. A 
preferred dry clay is quaternary ammonium bentonite, available from United 
Catalysts, Inc. under the trade name Advitrol 6-8. The prewet clay acts as 
an antisettling agent and also provides thixotropic properties to the 
composition while the dry clay provides fast shear viscosity, and also 
provides thixotropic properties. 
Preferably, the filler/glazing component includes a coloring agent to form 
a colored finish. Suitable coloring agents include black iron oxide, 
available from Pfizer, titanium dioxide (Rutile), available from SCM 
Chemicals under the designation TIONA RCL-9, and acetylene black, 
available from Chevron, Inc., with acetylene black being preferred due to 
its ability to provide better conductivity in a high resin formula. 
The filler/glazing component also preferably includes accelerating agents 
to speed up the curing time. Suitable accelerators include dimethyl 
aniline, available from Dupont under the designation N DMA, cobalt 
naphthenate or cobalt neodecanate, available from Mooney Chemical, Inc. 
under the designation TEN-CEM, copper naphthenate, potassium hexanoate, 
dimethyl para toluidine or mixtures thereof. 
The addition of a phosphosilicate to the filler/glazing component helps 
assure the adhesion of the coating to the molded FRP part and adds to the 
durability of the coating. A preferred phosphosilicate is calcium 
strontium zinc phosphosilicate. 
The first organic solvent is chosen from the group consisting of a highly 
volatile solvent, such as acetone, a solvent of medium volatility, such as 
ethyl acetate, and a solvent of low volatility, such as para methyl glycol 
ether acetate or mixtures thereof, with mixtures of such solvents being 
preferred. More preferably, a mixture of solvents is chosen such that 
their azeotropic evaporation rate is lowered, allowing more open time 
(i.e., the time the coating remains flowable for leveling purposes). 
The second organic solvent component is chosen from the group consisting of 
solvents of low volatility. Such solvents have high molecular weights and 
high flash points. Examples of such solvents are alkoxyalkanol solvents, 
2-butoxyethanol being preferred, and ketone solvents containing 5-10 
carbons, such as methyl amyl ketone, or mixtures thereof. The addition of 
the second organic solvent component to the filler/glazing component 
results in a coating wherein paint "pop-out" is reduced or eliminated and 
wherein there is not an undesireable degree of an "orange peel" effect. 
Therefore, the two most unique properties of the coating (its resistance 
to paint "pop-out" and its ability to provide a surface which, because of 
it does not exhibit an undesirable degree of an "orange peel" effect, is 
immediately suitable for subsequent application of top coats) are the 
result of the addition of the second organic solvent component to the 
filler/glazing component. 
Based on the foregoing, the preferred filler/glazing component of the 
coating comprises: from about 20% to 80% by weight of a resin selected 
from the group consisting of vinyl ester resins, and vinyl ester resins in 
combination with polyester resins; from about 2% to about 35% by weight of 
a sprayable filler such as talc, from about 0.1% to about 15% by weight of 
a mixture of thixotropic clays, from about 1-10% by weight of a 
phosphosilicate, from about 0-2% of an accelerator such as dimethyl 
aniline, cobalt naphthenate, copper napthenate, potassium hexanoate, 
dimethyl para-toluidine, cobalt neodecanate, or mixtures thereof; and from 
about 0% to about 20% by weight of a first organic solvent or organic 
solvent mixture. The filler/glazing component also includes optionally 
from 0-4% of a coloring agent selected from the group consisting of 
titanium dioxide, black oxide, acetylene black, or mixtures thereof, and 
from 0-40% of a styrene monomer. 
The coating further includes as a catalyst component from 1-50% and 
preferably about 2-6% of a catalyst selected from the group consisting of 
methyl ethyl ketone peroxide and cumyl hydrogen peroxide, with cumyl 
hydrogen peroxide being preferred. 
Still further, the coating includes, as a reduction step prior to addition 
of the catalyst component, a second organic solvent or organic solvent 
mixture of low volatility. 
More preferably, the filler/glazing component comprises: a combination of 
30-44% by weight of the overall filler/glazing components of a vinyl ester 
resin and 30-36% by weight of a polyester resin, 30-40% by weight of a 
styrene monomer, 0.1-4% by weight of a coloring agent selected from the 
group consisting of titanium dioxide, black oxide, acetylene black, or 
mixtures thereof, 0.1-2% of an accelerator selected from the group 
consisting of demethyl aniline, cobalt naphthenate, copper nathenate, 
potassium hexanoate, dimethyl para toluidine, cobalt neodecanoate, or 
mixtures thereof; from about 2-10% by weight of a filler such as talc; 
from about 1-4% by weight of a mixture of thixotropic clays, from about 
1-10% by weight calcium strontium zinc phosphosilicate, and from about 
5-10% by weight of a first organic solvent or organic solvent mixture. 
The coating further includes as a catalyst component from 1-50% and 
preferably about 2-6% of a catalyst selected from the group consisting of 
methyl ethyl ketone peroxide and cumyl hydrogen peroxide, with cumyl 
hydrogen peroxide being preferred. 
Still further, the coating includes, as a reduction step prior to addition 
of the catalyst component, a second organic solvent or organic solvent 
mixture selected from the group consisting of alkoxyalkanols and ketone 
solvents containing 5-10 carbons. 
Still more preferably, the filler/glazing component comprises: a 
combination of 40-42% by weight of the overall filler/glazing components 
of a vinyl ester resin and 30-36% by weight of a polyester resin, 30-40% 
by weight of a styrene monomer, 0.1-4% by weight of a coloring agent 
selected from the group consisting of titanium dioxide, black oxide, 
acetylene black, or mixtures thereof, 0.1-1% of an accelerator selected 
from the group consisting of dimethyl aniline, copper nathenate, cobalt 
neodecanoate, or mixtures thereof; from about 2-5% by weight of a filler 
such as talc; from about 0.1-1.0% by weight of a mixture of thixotropic 
clays, from about 1-10% by weight calcium strontium zinc phosphosilicate, 
and from about 5-10% by weight of a first organic solvent or organic 
solvent mixture. 
The coating further includes as a catalyst component from 1-50% and 
preferably about 2-6% of a catalyst selected from the group consisting of 
methyl ethyl ketone peroxide and cumyl hydrogen peroxide, with cumyl 
hydrogen peroxide being preferred. 
Still further, the coating includes, as a reduction step prior to addition 
of the catalyst component, from about 1-15% by weight of a second organic 
solvent or organic solvent mixture selected from the group consisting of 
alkoxyalkanols and ketone solvents containing 5-10 carbons. 
The most preferred filler/glazing component comprises: a combination of 
40-42% by weight of the overall filler/glazing components of a vinyl ester 
resin and 30-36% by weight of a polyester resin, 30-40% by weight of a 
styrene monomer, 0.1-2% by weight of a coloring agent selected from the 
group consisting of titanium dioxide, black oxide, acetylene black, or 
mixtures thereof, 0.01-0.5% of an accelerator selected from the group 
consisting of dimethyl aniline, copper nathenate, cobalt neodecanoate, or 
mixtures thereof; from about 2-5% by weight of a filler such as talc; from 
about 0.1-0.5% by weight of a mixture of thixotropic clays, from about 
4-6% by weight calcium strontium zinc phosphosilicate, and from about 
5-10% by weight of a first organic solvent or organic solvent mixture. 
The coating further includes as a catalyst component from 1-50% and 
preferably about 2-6% of a catalyst selected from the group consisting of 
methyl ethyl ketone peroxide and cumyl hydrogen peroxide, with cumyl 
hydrogen peroxide being preferred. 
The coating further includes, as a reduction step prior to addition of the 
catalyst component, 5-10% by weight of a second organic solvent or organic 
solvent mixture selected from the group consisting of alkoxyalkanols and 
ketone solvents containing 5-10 carbons. 
The coating of the present invention is applied as indicated in U.S. Pat. 
No. 5,371,117 which is hereby incorporated by reference and is dry to the 
touch in 10 minutes with heat, dry to handle in 30 minutes with heat, and 
recoatable in one hour with or without heat. This coating has very high 
percentages of reactive material (solids contents). It demonstrates 
superior adhesion to many various substances unlike most unsaturated 
compounds. This coating also demonstrates exceptional corosion resistance. 
It also demonstrates superior crosshatch adhesion to many dissimilar 
substrates and a high degree of flexibility which is uncommon to most 
coatings and especially unsaturated resin based coating. It is also bake 
temperature resistant, does not require sanding and demonstrates a high 
level of conductivity for subsequent electrostatic applications of top 
coats in its preferred embodiments. 
This coating also has high build capabilities when compared to conventional 
primer/highbuild primers. They are generally only capable of 0.8-2.5 mils 
of deposition, where the present coating can build up to 6 mils in 
subsequent wet on wet coats without sagging or running and without causing 
mud-cracking due to deposition or otherwise greatly affect the cure of the 
coating. 
Because the coating has an uncommonly high reactive volume concentration, 
it has the ability to fill and bridge all the areas of concern, even 
"low-density" material, thereby eliminating the solvent popping problems. 
Also, it has exceptional adhesion to unprepared SMC as tested via ASTM 
sanctioned cross-hatch adhesion test. 
While certain representative embodiments and details have been shown for 
purposes of illustrating the invention, it will be apparent to those 
skilled in the art that various changes in the product disclosed herein 
may be made without departing from the scope of the invention, which is 
defined in the appended claims.