Metal fixative in automative paint

An improved coating composition containing chlorinated polyolefin to provide superior orientation of metallic pigment flakes in the coating. The invention is particularly useful in the pigmented base coat of a base coat-clear coat coating since it permits the use of a thinner base coat which, because of the improved orientation of the metallic pigment flakes, provides superior hiding or masking of the coated substrate. The coating composition comprises a solvent, a film forming resin selected from the group consisting of acrylic, alkyd, polyester and polyurethane resins, a uniformly dispersed pigment and a chlorinated polyolefin. The multilayer coating composition comprises a base coat comprising a film forming resin selected from the group consisting of acrylic, alkyd, polyester and polyurethane in a solvent, a uniformly dispersed pigment and a chlorinated polyolefin, and a topcoat comprising a transparent coating composition deposited on said basecoat, said topcoat comprising a second film-forming resin selected from the group consisting of acrylic, alkyd polyester and polyurethane resin dispersed in a volatile organic solvent.

BACKGROUND OF THE INVENTION 
The present invention is directed to coating compositions for use as 
decorative finish or top coats for automobile vehicle bodies. 
In the automotive industry two significant systems are utilized in the 
painting of automobiles. One topcoat system which utilizes thermoplastic 
resins is known as the acrylic lacquer system. The other topcoat system 
used in the automotive industry is the thermosetting acrylic resin as 
described in U.S. Pat. No. 3,375,227, issued May 26, 1968. 
Because of environmental considerations, organic solvent reducible acrylic 
enamels of the foregoing type have been superseded in certain situations 
by water reducible acrylic enamels. 
Multilayer coating systems are also well known in the coating industry. 
These coating systems which comprise a thin aluminum flake pigmented base 
coat and a clear top coat are increasingly popular in the automotive 
industry. The majority of cars manufactured in Europe and Japan are 
painted with base coat-clear coat systems. The advantages of the base 
coat-clear coat multilayer coating system are numerous including 
outstanding appearance, superior gloss, improved chemical and mar 
resistance, and extended duty. In order to prepare these systems it has 
been required that each coat be baked or cured before a second or topcoat 
is applied. Thus several time consuming baking or curing steps are 
normally required where multilayer systems are applied. In U.S. Pat. No. 
3,639,147 a multilayer coating system is described that eliminates the 
need to bake or cure the base layer before the second or topcoat is 
applied. This multilayer coating system has been adapted by the original 
equipment paint industry. 
Repairing the base coat-clear coat finishes in the field has represented a 
problem. As previously mentioned, the multilayer coatings used by the OEM 
manufacturers must be baked in order to be useful. Repair shops require a 
base coat-clear coat refinish coating system which is capable of being 
dried in ambient room air. In addition, this refinish coating must match 
the characteristics of the OEM coating. 
This invention relates to the use of chlorinated polyolefins in a coating 
containing a metallic flake pigment thereby preventing metal flake 
disorientation. This invention further relates to a base coat-clear coat 
which can be applied in the field and dried under ambient room air 
conditions resulting in an applied coating which matches the OEM coating, 
wherein the basecoat contains chlorinated polyolefins. This invention is 
also applicable to base coat - clear coat OEM baked coatings. 
An advantage of this invention is that it permits the use of increased 
pigment concentrations in the base coat or top coat resulting in a thinner 
applied coating. 
The prior art contains several examples of polymeric coating compositions 
useful for refinishing or repairing damaged coatings in the field. An 
acrylic coating composition for refinishing flexible automobile and truck 
bumpers is shown in Sheppard U.S. Pat. No. 3,829,397 issued on Aug. 13, 
1974 and U.S. Pat. No. 3,893,960 issued on July 8, 1975. 
A water-based alkyd resin coating composition is shown in Miller U.S. Pat. 
No. 4,321,169 issued on Mar. 23, 1982. The coating composition disclosed 
in Miller can be dried at ambient temperatures and is useful for coating 
metal and plastic substrates and in particular for finishing or repairing 
automobiles and trucks. 
A acrylic coating composition for repairing acrylic lacquer coatings which 
are used in the auto industry is disclosed in Willey U.S. Pat. No. 
3,711,411 issued on Jan. 16, 1973. 
The disclosures of U.S. Pat. Nos. 3,829,397; 3,893,960; 4,321,169 and 
3,711,411 are incorporated by reference. 
Aesthetically, the acceptable appearance of a metallic pigmented coating is 
dependent upon the correct orientation of the metal particles. The 
acceptable appearance of a metalized coating is defined as that appearance 
which usually matches the appearances of a reference standard, or, if no 
such standard exists, the coating should exhibit a surface free from 
mottling, ghosting, general discontinuities, or any visual apparation 
signifying disorientation of the included metal. 
The formulation of metallic coatings generally is limited to small amounts 
of included metallic pigment. Usually, metallic pigments in excess of 3% 
of the coating composition will lead to metal disorientation characterized 
by application problems resulting in the loss of an acceptable appearance. 
In order to completely hide or cover the surface to be coated, repeated 
applications of the coating are required, often resulting in an 
excessively thick film. Excessively thick films are characterized by film 
embrittlement and general loss of adhesion and flexibility. Film thickness 
exceeding 2-2.5 mils are considered undesirable. A mil is defined as 0.001 
inches. 
Excessive film thickness is particularly prevalent when the metallic color 
coat is overlaid with a clear transparent coating designed to enhance 
gloss, durability and general aesthetics. 
When applying a clear overlay over a metallized basecoat, the desired film 
thickness can be achieved by applying a very thin layer of the basecoat, 
followed by a normal thickness application of the clear coat. In order to 
achieve complete hiding by the basecoat, more metallic pigment must be 
included in its composition without detriment to its appearance. Increased 
amounts of metallic pigment can be incorporated into the coating by 
introducing adjunct binder materials. These adjunct materials are 
characterized by a general lack of color, and an ability to protect the 
metal particles from disorientation during application. Such adjunct 
binders are currently employed by the industry. An example is a copolymer 
of polyethylene and vinyl acetate manufactured by Allied Chemical 
Corporation and designated as AC405. Other examples are a number of 
commercially available non aqueous acrylic resin dispersions as in U.S. 
Pat. No. 4,220,679. 
Ideally, an adjunct binder suitable for protecting metal flakes from 
disorientation during application: (1) should be uneffected by the 
presence of companion binders, (2) should not be influenced by the solvent 
combination employed in the coating formulation; (3) should not detract 
from the achievement of a desired color; and, (4) should be easily 
incorporated into any coating composition containing metal flakes using 
standard mixing procedures. Chlorinated polyolefins meet the previously 
stated requirements. 
The problems and disadvantages associated with prior art base coat-clear 
coat refinish paint systems are overcome in accordance with the present 
invention wherein the addition of a chlorinated polyolefin resin to the 
base coat results in the metal fixation needed for proper color match and 
appearance. 
SUMMARY OF THE INVENTION 
The benefits and advantages of the present invention are achieved by 
incorporating a chlorinated polyolefin into a base coat formulation. 
Among the base coats which are useful according to the processes of this 
invention are those commonly known as alkyd resins which are defined to 
include fatty acid or oil containing esterification products. The methods 
for preparing these resins are well known in the art. In general two basic 
methods are used. In the first a fatty acid is reacted with a mixture of 
polyols and polybasic acids such as glycerine and phthalic anhydride. The 
second method commonly used entails the alcoholysis of a fatty oil such as 
cocoanut oil with a polyol such as pentaerythritol and then the further 
condensation of this reaction product with polyols and polybasic acids as 
above. 
The preferred alkyd resins useful in this invention are those containing 
from about 5 to about 65 weight percent of a fatty acid or oil and having 
an hydroxyl equivalent to carboxy equivalent ratio of from about 1.05 to 
1.75. Alkyd resins having less than about 5 percent fatty compound are 
classified as the "oil-less" alkyd resins or polyester resins described 
hereinafter. On the other hand, alkyd resins containing greater than 65 
percent of a fatty compound exhibit poor baking properties, poor chemical 
resistance and unsatisfactory adhesion to either the base coat or the 
substrate. When the hydroxyl to carboxyl equivalent ratio is less than 
about 1.05 gelation can result during polymer preparation while resins 
prepared having a ratio in excess of 1.75 have low molecular weights and 
therefore poor chemical resistance. 
These alkyd resins can also be used as the topcoat of this invention. When 
this is the case it is preferred that the oil or fatty acid portion of the 
alkyd resin contain a light colored baking oil or fatty acid such as 
cocoanut or dehydrated castor oils or fatty acids. Furthermore, when these 
resins are used as topcoats they can be reacted with various acrylic or 
ethylenically unsaturated monomers as described above to produce vinyl 
modified alkyd resins. 
Curing of these alkyd resins can be accomplished by blending with any of 
the widely known cross-linking agents in the same weight ratios as are 
used with carboxy-hydroxy copolymers. 
Included among the various fatty acids and oils useful in preparing these 
alkyd resins are the fatty acids derived from the following oils: castor, 
dehydrated castor, cocoanut, corn, cottonseed, linseed, oticica, perilla, 
poppyseed, safflower, soybean, tung oil, etc., and the various rosins 
containing tall oil fatty acids. Useful polyols include the various 
glycols, such as ethylene glycol, propylene glycol, neopentyl glycol, 
butylene glycol, 1,4 butanediol, hexylene glycol, 1,6 hexanediol, the 
polyglycols such as diethylene glycol or triethylene glycol, etc., the 
triols such as glycerine, trimethylol ethane, trimethylol propane, etc., 
and other higher functional alcohols such as pentaerythritol, sorbitol, 
mannitol, and the like. Acids useful in preparing the alkyd resins of this 
invention include monofunctional acids such as rosin acids, benzoic acid, 
para tertiary butyl benzoic acid and the like; the polyfunctional acids 
such as adipic acid, sebacic acid, phthalic acid or anhydride, isophthalic 
acid, terephthalic acid, dimerized and polymerized fatty acids, 
trimellitic acid, and the like. 
In another instance the base coat film is produced from resins known as 
polyesters or "oil-less" alkyd resins. These resins are prepared by 
condensing nonfatty containing polyols and polyacids. Included among the 
useful polyacids are isophthalic acid, phthalic acid or anhydride, 
terephthalic acid, maleic acid or anhydride, fumaric acid, oxalic acid, 
sebacic acid, azelaic acid, adipic acid, etc. Monobasic acids such as 
benzoic, para tertiary butyl benzoic and the like can also be utilized. 
Among the poly alcohols are the diols or glycols such as propylene glycol, 
ethylene glycol, butylene glycol, 1-4-butanediol, neopentyl glycol, 
hexylene glycol, 1,6-hexanediol, and the like; the triols such as 
trimethylol ethane, trimethylol propane and glycerine and various other 
higher functional alcohols such as pentaerythritol. 
The preferred type of polyester resin comprises the reaction product of 
aromatic and aliphatic mono and dibasic acids with a mixture of diols and 
higher functional alcohols. In order to obtain the optimum cure properties 
and molecular weight it is desirable for the ratio of the equivalents of 
hydroxyl in the alcohol reactants to the equivalents of acid in the acid 
reactants to be from about 1.1:1 to 1.75:1. Polyester resins having 
hydroxy to carboxyl equivalents ratios of less than about 1.1 generally 
gel before preparation is complete while those having ratios in excess of 
1.75 are too low in molecular weight to have acceptable chemical 
resistance properties. 
Utilizing the process of this invention offers a means of combining the 
desirable properties of a combination of resin systems. For example, in 
automotive finishes the pigment control properties of acrylic lacquers can 
be combined with the chemical resistance properties of thermosetting 
acrylic resins by applying a thermosetting acrylic clear coat over a 
thermoplastic acrylic lacquer base coat. Likewise in appliance finishes 
the chemical resistance of polyester resins can be combined with the lower 
cost of thermosetting acrylic resins by applying a polyester clear topcoat 
over a pigmented thermosetting acrylic base coat. 
Especially preferred is a 1:1 blend of two resins. The first is a fatty 
acid oil modified acrylic polymer and the second is a 40% acrylated alkyd 
resin cured with moderate levels of cobalt and zinc dryers. In addition, 
various urethane polymers can also be used in forming the base coat or 
especially the transparent topcoat of this invention. These polymers can 
be prepared by several well-known methods. 
A distinct advantage of this invention when incorporating a chlorinated 
polyolefin is the control of pigment dispersion and orientation in the 
film when sprayed. Pigment control is evidenced by the "standard metallic 
appearance" which is the striking appearance of depth when the angle of 
incidence varies over curved surfaces. In this invention the pigments 
which are in the base coat and particularly metallic flakes, such as 
aluminum flakes, remain properly orientated and dispersed in the film as 
the film is applied, when the base film is overcoated with the transparent 
topcoat. The chlorinated polyolefin is preferably incorporated into the 
base coat by inclusion into the formulation of resin, pigment and solvent, 
if any, before coating. In some instances additional improvements in this 
orientation and dispersion are obtained during a baking operation, i.e., 
the appearance of depth in the baked film is better than that in the wet 
film. As stated above, pigment control is retained in the base coat while 
it is being overcoated. This is evidenced by lack of "strike-in" or 
migration of the two films (the base coat and topcoat) into each other. 
When "strike-in" occurs, pigments move from the base coat into the 
topcoat, the film compositions become intermixed at the interface and the 
baked coating composition has a dusty appearance rather than a clear 
"depth" appearance. Sufficient wetting takes place at the interface so 
that no problems of delamination and solvent release from either coating 
are obtained. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The coating composition useful in the base coat of the present invention 
comprises a substantially uniform mixture or dispersion of a vehicle 
comprising a resin binder and a solvent comprising a volatile organic 
solvent in further combination with a chlorinated polyoefin and a suitable 
pigment. 
Typical of the useful resin binders are acrylic alkyd and polyester resins. 
Useful chlorinated polyolefins include those commercially available from 
Hercules, Inc., Eastman Chemical Products, Inc., Chugai International 
Corporation and Sorbin Chemicals, Inc. 
A preferred embodiment of the invention contains the following ingredients: 
3-10% pigment, 05-0.2% suspension aid, 5-25% chlorinated polyolefin 
solution, 20-50% film-forming resin, and 40-75% volatile organic resin 
solvent. This composition, when sprayed on a suitable substrate, both with 
and without a clear coat overlay, exhibits a superior surface free from 
mottling, ghosting, general discontinuities or any apparition signifying 
disorientation of the pigment. 
A clear coat contains 30-60% film-forming resin and 40-70% volatile organic 
solvent.

In order to further illustrate the coating compositions of the present 
invention, the following examples are provided. It will be understood that 
the examples are provided for illustrative purposes and are not to be 
restrictive of the scope of the invention as herein described and as set 
forth in the claims. 
EXAMPLES 1-2 
These examples illustrate the effects of adding a chlorinated polyolefin as 
a fixative for metallic flakes to an acrylic coating composition. In these 
examples, a control composition comprising an aluminum pigmented 
thermoplastic acrylic coating composition (Example 1) and a test 
composition (Example 2) having substantially the same composition except 
that it contained approximately 5% by weight chlorinated polyolefin 
solution, were prepared using standard thermoplastic acrylic coating 
composition mixing procedures. The compositions had the following 
formulations: 
______________________________________ 
Weight % 
Ingredients Ex. No. 1 
Ex. No. 2 
______________________________________ 
Medium Aluminum Pigment (1) 
3.1 3.2 
Toluene 3.1 3.2 
Suspension Aid (2) 0.1 0.1 
Chlorinated Polyolefin (3) 
-- 5.0 
Thermoplastic Acrylic 
36.5 34.0 
Vehicle (4) 
Acrylic Lacquer Thinner (5) 
57.2 54.5 
______________________________________ 
(1) a pigment paste consisting of 60% aluminum flake and 40% aliphatic 
naphtha. 
(2) AntiTerra U brand suspending aid manufactured by K. Mallinckrodt. 
(3) Eastman Chlorinated Polyolefin 3431 comprising a solution of 50% 
solids in xylene. 
(4) A 34.2% solids solution of a blend of an acrylic resin comprising 
methyl methacrylate and isobutyl methacrylate, cellulose acetate butyrate 
and phthalate plasticizer in a solvent consisting of 2.91% isopropyl 
alcohol, 3.24% cellosolve acetate, 10. 37% methyl ethyl ketone, 0.4% 
methyl isobutyl ketone, 0.4% aliphatic naphtha, 37.77% toluene, 1.40% 
xylene and 8.4% Solvesso (an aromatic naphtha). 
(5) A blend consisting of 25% acetone, 20% V.M & P naphtha, 20% ethylene 
glycol ethylether acetate, 15% isopropyl alcohol, 10% toluene and 5% 
xylene. 
The above compositions were sprayed onto 12".times.6" substrates both with 
and without clear coat overlays. The film thickness was less than 2.5 
mils. The coating was allowed to dry in ambient room air. 
Example 1, the control composition, exhibited a disturbance of the 
metallized surface resulting from disorientation of the metal flakes. 
Example 2, the composition containing the chlorinated polyolefin, 
exhibited a surface free from mottling, ghosting, general discontinuities, 
or any visual apparition signifying disorientation of the included metal 
flakes. 
EXAMPLES 3-4 
These examples illustrate the effects of adding a chlorinated polyolefin as 
a fixative for metallic flakes to an acrylic enamel coating composition. 
In these examples, a control composition comprising an aluminum pigmented 
acrylated enamel coating composition (Example 3) and a test composition 
(Example 4) having substantially the same composition except that it 
contained approximately 5% by weight chlorinated polyolefin solution, were 
prepared using standard acrylated enamel coating composition mixing 
procedures. The compositions had the following formulations: 
______________________________________ 
Weight % 
Ingredients Ex. No. 3 
Ex. No. 4 
______________________________________ 
Medium Aluminum Pigment of 
3.1 3.2 
Examples 1 and 2 
Toluene 3.1 3.2 
Suspension Aid of Examples 
0.1 0.1 
1 and 2 
Chlorinated Polyolefin of 
-- 5.0 
Examples 1 and 2 
Acrylated Enamel Vehicle (1) 
33.8 31.6 
Acrylic Lacquer Thinner of 
59.9 56.9 
Examples 1 and 2 
______________________________________ 
(1) A blend of (I) an acrylated alkyd resin derived from vegetable oil 
fatty acids, an aliphatic polyol, mono & dibasic aromatic acids modified 
with esters of acrylic and methacrylic acids and an aromatic substituted 
vinyl monomer, and (II) a vegetabl e oil fatty acid modified polymer of 
esters of acrylic and methacrylic acids and an aromatic substituted vinyl 
monomer. 
The above compositions were sprayed onto 12".times.16" substrates both with 
and without clear coat overlays; the film thickness was less than 2.5 
mils. The coating was allowed to dry in ambient room air. 
Example 3, the control composition, exhibited a gross disturbance of the 
metallized coating resulting from disorientation of the metal flakes. 
Example 4, the composition containing the chlorinated polyolefin, 
exhibited a surface free from mottling, ghosting, general discontinuities, 
or any visual apparition signifying disorientation of the included metal 
flakes. 
EXAMPLES 5-6 
These examples illustrate the effects of adding a chlorinated polyolefin as 
a fixative for metal flakes to an alkyd enamel coating composition. In 
these examples, a control composition comprising an aluminum pigmented 
alkyd enamel coating composition (Example 5) and a test composition 
(Example 6) having substantially the same composition except that it 
contained approximately 5% by weight chlorinated polyolefin solution, were 
prepared using standard thermoplastic acrylic coating composition mixing 
procedures. The compositions had the following formulations: 
______________________________________ 
Weight % 
Ingredients Ex. No. 5 
Ex. No. 6 
______________________________________ 
Medium Aluminum Pigment 
3.1 3.2 
of Examples 1, 2, 3 & 4 
Toluene 3.1 3.2 
Suspension Aid of Examples 
0.1 0.1 
1, 2, 3 & 4 
Chlorinated Polyolefin of 
-- 5.0 
Examples 1, 2, 3 & 4 
Alkyd Vehicle (1) 30.8 28.8 
Alkyd Enamel Thinner (2) 
62.9 59.7 
______________________________________ 
(1) A 40% solids solution of an alkyd resin derived from vegetable oil 
fatty acids, an aliphatic polyol and mono and dibasic aromatic acids in a 
solvent consisting of 25% aliphatic naphtha, 20% V.M & P naphtha and 15% 
xylene. 
(2) A blend consisting of 53% V.M & P naphtha, 21% lactol spirits, 11% 
ethylene glycol ethyl ether acetate, 5% ethyl acetate, 5% Solvesso 150 
(aromatic hydrocarbon) and 5% toluene. 
The above compositions were sprayed onto 12".times.16" substrates both with 
and without clear coat overlays. The film thickness was less than 2.5 
mils. The coating was allowed to dry in ambient room air. 
Example 5, the control composition, exhibited disturbance of the metallized 
coating resulting from disorientation of metal flakes. Example 6, the 
composition containing the chlorinated polyolefin, exhibited a surface 
free from mottling, ghosting, general discontinuities or any visual 
apparition signifying disorientation of the included metal flakes. 
EXAMPLE 7 
A coating composition is made comprising: 
6%: uniformly dispersed pigment of Examples 1-6 
6%: toluene 
0.1%: suspending aid of Examples 1-6 
10%: chlorinated polyolefin solution of Examples 1-6 
28.1%: thermoplastic acrylic vehicle of Examples 1 and 2 
50% acrylic lacquer thinner of Examples 1 and 2. 
The above composition is sprayed onto a suitable substrate both with and 
without a clear overlay. The composition exhibited a surface free from 
mottling, ghosting, general discontinuities or any apparition signifying 
disorientation of the included metal flakes. 
EXAMPLE 8 
A coating composition is made comprising: 
10%: uniformly dispersed pigment of Examples 1-7 
10%: toluene 
0.2%: suspending aid of Examples 1-7 
20%: chlorinated polyolefin solution of Examples 1-7 
20.8%: acrylated enamel vehicle of Examples 3.gtoreq.4 
39%: acrylic lacquer thinner of Examples 3-4. 
The above composition is sprayed onto a suitable substrate both with and 
without a clear overlay. The composition exhibited a surface free from 
mottling, ghosting, general discontinuities or any apparition signifying 
disorientation of the included metal flakes. 
EXAMPLE 9 
A coating composition is made comprising: 
3%: uniformly dispersed pigment of Examples 1-8 
3%: toluene 
0.05%: suspending aid of Examples 1-8 
4%: chlorinated polyolefin dispersion of Examples 1-8 
42%: alkyd vehicle of Examples 5-6 
47.5%: alkyd enamel thinner of Examples 5-6. 
The above composition is sprayed onto a suitable substrate both with and 
without a clear overlay. The composition exhibited a surface free from 
mottling, ghosting, general discontinuities or any apparition signifying 
disorientation of the included metal flakes.