Coating process

A coated object is produced by flame spraying the object with a substantially molten polymeric material which comprises a linear alternating polymer of ethylene and at least one ethylenically unsaturated hydrocarbon optionally blended with a copolymer of ethylene and .alpha.,.beta.-ethylenically unsaturated carboxylic acid.

FIELD OF THE INVENTION 
This invention relates to a process for coating an object with a linear 
alternating polymer of carbon monoxide and at least one ethylenically 
unsaturated hydrocarbon. More particularly, the invention relates to a 
flame spraying process for coating a solid object with a polymeric 
material comprising the linear alternating polymer or a blend thereof with 
a copolymer of ethylene and an unsaturated carboxylic acid. 
BACKGROUND OF THE INVENTION 
The class of polymers of carbon monoxide and olefin(s) is well known in the 
art. Early methods for the production of various types of such polymers 
are illustrated by Brubaker, U.S. Pat. No. 2,495,286, U.K. Pat. No. 
1,081,304 and Nozaki, U.S. Pat. No. 3,694,412. More recently, the class of 
linear alternating polymers of carbon monoxide and at least one 
ethylenically unsaturated hydrocarbon, e.g., ethylene or ethylene and 
propylene, has become of greater interest in part because of the greater 
availability of the polymers. These polymers, often referred to as 
polyketones or polyketone polymers, have been shown to be of a structure 
of the repeating formula --CO--(A) wherein A is the moiety of 
ethylenically unsaturated hydrocarbon polymerized through the ethylenic 
unsaturation. For example, when the unsaturated hydrocarbon is ethylene, 
the polymer is represented by the repeating firmula --CO(CH.sub.2 
--CH.sub.2 --. The general process for the production of such polymers is 
illustrated by a number of published European patent applications 
including Nos. 0.121,965 and 0.181,014. The process generally involves the 
use of a catalyst formed from a compound of palladium, nickel or cobalt, 
the anion of a non-hydrohalogenic strong acid and a bidentate ligand of 
phosphorus, arsenic or antimony. 
The polyketone polymers are relatively high molecular weight thermoplastics 
of known utility in the production by conventional techniques of shaped 
articles for use in the food and drink industry and for automotive parts. 
It is, on occasion, useful to blend the polyketone polymers with other 
polymeric materials to retain the more desirable properties of the 
polyketone while improving other properties. For example, polyketone 
polymer is blended with a copolymer of ethylene and an unsaturated 
carboxylic acid, e.g., a copolymer of ethylene and acrylic acid, to 
produce blends having improved melt stability. Such blends are disclosed 
and claimed in copending U.S. patent application Ser. No. 135,429, filed 
Dec. 21, 1987, now abandoned (Docket No. T-4235). 
The polyketones or the blends with copolymer of ethylene and unsaturated 
carboxylic acid, are shaped and/or formed by a variety of conventional 
techniques such as extrusion or injection molding into objects of known 
utility. For other purposes, it would be of advantage to coat objects with 
a coating of the polyketone polymer or blend thereof with 
ethylene/unsaturated carboxylic acid copolymer. 
SUMMARY OF THE INVENTION 
The present invention relates to a process for coating objects with a 
linear alternating polymer of carbon monoxide and at least one 
ethylenically unsaturated hydrocarbon and to the coated objects thereby 
produced. More particularly, the present invention relates to a process 
for flame spray coating an object with the linear alternating polymer or 
blend thereof with an ethylene/unsaturated acid copolymer to coat the 
object. The invention also relates to the coating objects thereby 
produced. 
DESCRIPTION OF THE INVENTION 
The polymeric material employed to flame spray coat objects according to 
the process of the invention is a polyketone polymer optionally blended 
with a copolymer of ethylene and certain .alpha.,.beta.-ethylenically 
unsaturated carboxylic acids. 
The polyketone polymer which is employed in the process of the invention is 
a linear alternating polymer of carbon monoxide and at least one 
ethylenically unsaturated hydrocarbon. Suitable ethylenically unsaturated 
hydrocarbons for use as precursors of the polyketone polymers have up to 
20 carbon atoms inclusive, preferably up to 10 carbon atoms inclusive, and 
are aliphatic such as ethylene and other .alpha.-olefins including 
propylene, butylene, isobutylene, 1-hexene, 1-octene and 1-dodecene, or 
are arylaliphatic containing an aryl substituent on a carbon atom of an 
otherwise aliphatic molecule, particularly an aryl substituent on a carbon 
atom of the ethylenic unsaturation. Illustrative of this latter class of 
ethylenically unsaturated hydrocarbons are styrene, m-methylstyrene, 
p-ethylstyrene and p-methylstyrene. Preferred polyketones are copolymers 
of carbon monoxide and ethylene or terpolymers of carbon monoxide, 
ethylene and a second hydrocarbon of at least 3 carbon atoms, particularly 
an .alpha.-olefin such as propylene. 
The structure of the polyketone polymers is that of a linear alternating 
polymer of carbon monoxide and ethylenically unsaturated hydrocarbon and 
contains substantially one molecule of carbon monoxide for each molecule 
of hydrocarbon. When terpolymers of carbon monoxide, ethylene and a 
asecond hydrocarbon are employed, there will be within the terpolymer at 
least two units incorporating a moiety of ethylene for each unit employing 
a moiety of the second hydrocarbon. Preferably there will be from about 10 
units to about 100 units incorporating a moiety of ethylene per unit 
employing a molecule of the second hydrocarbon. The polymer chain is 
therefore illustrated by the formula 
EQU [CO(CH.sub.2 --CH.sub.2)].sub.x [CO--(B)].sub.y 
wherein B is the moiety of the second hydrocarbon polymerized through the 
ethylenic unsaturation. The --CO--(CH.sub.2 --CH.sub.2) units and the 
--CO(B) units are found randomly throughout the polymer chain and the 
ratio of y:x is no more than about 0.5. In the modification of the 
invention where copolymer of ethylene and carbon monoxide is employed, the 
polymer is illustrated by the above formula wherein y=0. When y is other 
than 0, as in the case of terpolymers, ratios of y:x from about 0.1 to 
about 0.01 are preferred. The end groups or "caps" of the polymer chain 
will depend on what materials are present during the production of the 
polymer and whether and how the polymer is purified. The precise nature of 
the end groups is of little significance so far as the overall properties 
of the polymer are concerned so that the polyketone polymer is fairly 
represented by the above formula. Of particular interest are the polymers 
of molecular weight from abut 1,000 to about 200,000, particularly those 
polyketone polymers of molecular weight from about 10,000 to about 50,000. 
The physical properties of the polymers will depend in part on whether the 
polymer is a copolymer on a terpolymer and the relative proportion of 
second hydrocarbon present in the case of terpolymers. Typical melting 
points of such polymers are from about 175.degree. C. to about 300.degree. 
C., but more typically from about 210.degree. C. to about 270.degree. C. 
The polymers have limiting viscosity numbers (measured at 60.degree. C. in 
m-cresol) of from about 0.5 to about 10, more commonly from about 0.8 to 
about 4, as measured in a standard capillary viscosity measuring device. 
A method of producing the polymers which is now becoming conventional is to 
contact the carbon monoxide and hydrocarbon(s) in the presence of a 
catalyst composition formed from a palladium compound, the anion of a 
non-hydrohalogenic acid having a pKa below about 6 and a bidentate 
phosphorus ligand of defined structure. The scope of the process of 
producing the polyketone polymer is extensive, but without wishing to be 
limited, the preferred palladium compound is a palladium carboxylate, 
particularly palladium acetate, the preferred anion is the anion of 
trifluoroacetic acid or p-toluenesulfonic acid and the preferred bidentate 
phosphorus ligand is 1,3-bis(diphenylphosphino)propane or 
1,3-bis[di(2-methoxyphenyl)phosphino]propane. Such a process for 
polyketone production is illustrated by copending U.S. patent application 
Ser. No. 930,468, filed Nov. 14, 1986 (Docket No. K-0722). 
Polymerization is conducted under polymerization conditions in the gas 
phase or in a liquid phase in the presence of a liquid diluent, e.g., an 
alkanol such as methanol or ethanol. The reactants and catalyst 
composition are contacted by conventional means such as shaking or 
stirring. Suitable reaction temperatures are from about 20.degree. C. to 
about 150.degree. C. with preferred reaction temperatures being from about 
50.degree. C. to about 135.degree. C. Typical reaction pressures are from 
about 1 bar to about 200 bar, more typically from about 10 bar to about 
100 bar. Subsequent to reaction the polymer product is recovered as by 
filtration or decantation. The polyketone polymer may contain residues of 
the catalyst which are removed, if desired, by treatment of the polymer 
with a solvent or a complexing agent which is selective for the residues. 
The flame spray process of the invention is usefully conducted employing 
the polyketone polymer without the addition of other materials. However, 
conventional additives such as antioxidants and stabilizers which are 
designed to improve the properties of the coated object may be 
incorporated within the polyketione polymer. In a particular embodiment, 
however, the polyketone is blended with a second polymeric component and 
the resulting blend is employed in the flame coating process. A second 
polymeric material preferred as a co-component of a polymer blend when a 
blend is employed in the process of the invention is a copolymer of 
ethylene and .alpha.,.beta.-ethylenically unsaturated carboxylic acid. 
Although a variety of such unsaturated carboxylic acids of up to 10 carbon 
atoms inclusive, or in some cases even more, is useful as a monomer in the 
ethylene copolymers, e.g., 2-hexenoic acid, 2A-octenoic acid and 
2-decenoic acid, the preferred ethylenically unsaturated acids are those 
of up to 4 carbon atoms inclusive which are acrylic acid, methacrylic acid 
and crotonic acid. Methacrylic acid and acrylic acid are particularly 
preferred components of the ethylene/unsaturated carboxylic acid 
copolymer. 
The ethylene/unsaturated carboxylic acid copolymers are those copolymers 
having a relatively large proportion of ethylene and a relatively small 
proportion of the unsaturated carboxylic acid. Suitable ethylene 
copolymers have from about 0.1% by weight to about 35% by weight of 
unsaturated carboxylic acid, based on the total copolymer. Preferably, the 
copolymers have from about 1% by weight to about 20% by weight of the 
unsaturated carboxylic acid on the same basis. 
The method by which the copolymers are prepared is not critical and 
ethylene/unsaturated acid copolymers produced by a variety of methods are 
usefully employed when polyketone blends are used in the flame spraying 
process. A number of ethylene/acrylic acid and ethylene/methacrylic acid 
copolymers are commercially available. A particularly useful class of 
ethylene/acrylic acid copolymers is marketed by Dow Chemical Company under 
the tradename PRIMACOR.RTM.. A general discussion of the production of 
ethylene/unsaturated carboxylic acid copolymers is found in Thompson et 
al, U.S. Pat. No. 3,520,861 and Armitage, U.S. Pat. No. 4,351,931, the 
disclosures of which are incorporated herein by reference. 
As stated, the process of the invention is usefully conducted with the 
polyketone polymer without the presence of an ethylene/unsaturated acid 
blended therewith. The preferred method of operating the process of the 
invention is an alternate embodiment, however, wherein the polymeric 
material employed as feed for the flame spraying process is a blend of the 
polyketone and the ethylene/unsaturated carboxylic acid copolymer. When 
such a blend is employed, blends containing up to about 80% by weight, 
based on total blend, of the ethylene/unsaturated carboxylic acid 
copolymer may be used, however, blends of up to about 35% by weight are 
satisfactory. Blends containing from about 0.1% by weight to about 10% by 
weight of ethylene/unsaturated carboxylic acid copolymer, based on total 
blend, are preferred and particularly preferred, when bends are to be 
employed, are polyketone blends containing from about 3% by weight to 
about 7% by weight, on the same basis, of the ethylene/unsaturated 
carboxylic acid copolymer. 
The method of forming a blend to be used in the process of the invention, 
when blends are employed, is not material so long as a uniform blend of 
the components is produced without undue degradation of the components or 
the resulting blend. In one modification the polyketone polymer and the 
ethylene/unsaturated carboxylic acid copolymer are coextruded to produce 
the blend as an extrudate. In an alternate modification, the components 
are dry blended as powders or blended in a mixing device which exhibits 
high shear. The polyketone blend with ethylene/unsaturated carboxylic acid 
copolymer is a non-miscible blend wherein the ethylene/unsaturated acid 
copolymer exists as a discrete phase in the polyketone matrix. 
Satisfactory phase size for use in the invention on the order of from 
about 0.2 micron to about 1.5 micron, preferably from about 0.5 micron to 
about 1.0 micron. The blend is, of course, not homogeneous but good 
results are obtained in the process of the invention when the blend is a 
uniform mixture of the dispersed ethylene/unsaturated carboxylic acid 
copolymer in the continuous polyketone phase. 
The blends used in the process of the invention may optionally contain 
other conventional additives such as antioxidants, stabilizers and fire 
retardant materials and other additives designed to improve the 
processability of the polymers or improve the properties of the resulting 
blend. Such additives are added by conventional methods prior to, together 
with or subsequent to the blending of the component polymers. 
The general methods of flame spraying polymeric or other finely divided 
materials are known in the art. The basic concept of flame spraying of 
thermoplastic polymeric materials involves an apparatus wherein the 
polymeric material, a fuel and oxygen-containing gas are introduced into a 
combustion chamber wherein the fuel and oxygen-containing gas mixture 
ignites, thereby giving off heat which serves to substantially melt the 
polymeric material. The molten polymeric material is thereafter propelled 
from the combustion chamber by a source of propelling gas onto the surface 
of the object to be coated. An alternate modification of the process, also 
often termed flame spraying, although not directly involving a flame, 
employs the use of a heated wire or filament to melt the polymer to be 
sprayed. The use of a flame produced by combustion of a fuel in air is 
generally preferred. 
Illustrative fuels are generally low-molecular weight hydrocarbons which 
ignite easily and are normally gaseous at ambient conditions. Examples of 
suitable fuels include propane, propylene, ethylene and acetylene. As the 
oxygen-containing gas employed to cause combustion of the fuel, a variety 
of mixtures of oxygen and other non-combustible gases are usefully 
employed. Air is preferred. A variety of gaseous materials is useful as 
the propelling gas including nitrogen, argon and helium. Largely for 
convenience and economy, the use of air as the propelling gas as well as 
the combustion gas is preferred. Examples of such flame spraying processes 
and apparatus therefor are known in the art. A particularly useful process 
and equipment for use in the process is described in Reimer, U.S. Pat. No. 
4,632,309. Other related processes are illustrated by U.S. Pat. Nos. 
4,604,306, 3,723,165 and 3,440,079. 
In a representative embodiment of the process of the invention the 
polymeric material comprising the polyketone polymer optionally blended 
with ethylene/unsaturated carboxylic acid, provided in a finely divided 
powder form, is mixed with propane fuel and air and passed to a combustion 
chamber where the fuel and air are ignited, thereby providing the energy 
required to substantially melt the polymeric material. The molten 
polymeric material is propelled from the combustion chamber and from the 
apparatus through the use of compressed air as a propelling carrier gas 
and is allowed to impact upon an object, the coating of which is desired. 
The target object, being relatively cool, will cause the molten polymer to 
solidify and thereby provide the coating. 
The state of division of the polymeric material powder as well as the 
viscosity of the polyketone polymer, is important in obtaining good 
coatings on the target object. The polymeric material to be flame sprayed 
should be of a size from about 20 mesh to about 100 mesh, preferably from 
about 50 mesh to about 80 mesh. The limiting viscosity number of the 
polyketone polymer (LVN, measured at 60.degree. C. in m-cresol) should be 
from about 0.5 to about 1.8 and preferably is below 1.4. 
The object to be coated is a solid object for which a tough, wear and 
corrosion resistant coating is desired and objects of metal, glass, 
ceramic, plastic or other material are coated by the present process. More 
frequently, the process is employed to provide a coating of polyketone or 
blend thereof on metal objects. The process of the invention may be used 
in conjunction with other polymeric coatings wherein the object to be 
coated has a base coat of a first polymeric composition, such as a 
polyolefin, and a subsequent top coat of polyketone ior polyketone blend. 
Alternatively, the coating comprising polyketone may be used to provide a 
base coat suitable for subsequent top coating with a second composition. 
The process is particularly suitable for coating both internal and 
external automotive parts such as drive shafts and suspension springs and 
for coating storage tanks, food processing equipment and industrial pipe.

The invention is further illustrated by the following Illustrative 
Embodiments which should not be construed as limiting. 
ILLUSTRATIVE EMBODIMENT I 
A linear alternating copolymer of carbon monoxide and ethylene was produced 
by contacting the carbon monoxide and ethylene in the presence of a 
catalyst composition formed from palladium acetate, the anion of 
trifluoroacetic acid and 1,3-bis[di(2-methoxyphenyl)phosphino]propane. The 
copolymer had a melting point of 250.degree. C. and a LVN (measured at 
60.degree. C. in m-cresol) of 1.3. 
Three linear alternating terpolymers of carbon monoxide, ethylene and 
propylene were separately produced in the presence of catalyst 
compositions formed from palladium accetate, the anion of trifluoroacetic 
acid and 1,3-bis(di(2-methoxyphenyl)phosphino)propane. The terpolymers 
each had a melting point of about 220.degree. C. and LVN (measured at 
60.degree. C. in m-cresol) of 1.2, 1.6 and 2.2, respectively 
ILLUSTRATIVE EMBODIMENT II 
The terpolymers of Illustrative Embodiment I were separately employed in a 
flame spraying process to coat metal plates of aluminum and steel 
approximately 3 in. by 7 in. with a thickness of 1/16 in. The terpolymers 
were used as powders of roughly 50 to 80 mesh and the powders were dried 
prior to use. 
The metal plates were flame dried and then coated by flame spraying for 
approximately four minutes each until a film coating thickness of 30 mils 
was achieved on each plate. The bond of the polymer coating to the metal 
plates was tested in ASTM Crosshatch Adhesion Test #D3359-78. In this 
standardized test procedure, a six-blade cutting apparatus was first used 
to score and crosshatch the polymer coating down to the metal surface. A 
special ASTM adhesive tape was applied to the top surface of the coating 
and subsequently pulled from the surface at an acute angle to test the 
adhesion of the coating to the metal substrate. The adhesion of the 
coating is rated from 1 to 5 according to the number of crosshatch squares 
that are removed by the tape, 5 being the highest rating. The coatings 
prepared with the terpolymers of Illustrative Embodiment I were all rated 
5. 
ILLUSTRATIVE EMBODIMENT III 
The copolymer of Illustrative Embodiment I was blended separately with 30% 
by weight, based on total blend, of Primacor 1430.RTM. and Primacor 
5990.RTM. ethylene-acrylic acid copolymers. Primacor 1430 is a copolymer 
of ethylene and 9.5% by weight based on copolymer of acrylic acid. 
Primacor 5990 is a copolymer of ethylene and 20% by weight based on 
copolymer of acrylic acid. The blend of Primacor 5990 copolymer also 
contained carbon black as a colorizing agent. 
The blends were employed in a flame spraying process as in Illustrative 
Embodiment II to coat aluminum and steel plates. The coatings were tested 
after they were prepared in ASTMA Crosshatch Adhesion Test #D3359-78, as 
in Illustrative Embodiment II. All of the coatings were rated 5. 
ILLUSTRATIVE EMBODIMENT IV 
The terpolymer of Illustrative Embodiment I having an LVN of 2.2 was 
blended separately with 20, 40, 60 and 80% by weight, based on total 
blend, iof Primacor 1430 ethylene-acrylic acid copolymer. The blend was 
employed in a flame spraying process to coat metal plates as in 
Illustrative Embodiment II and the coatings were tested in the ASTM 
Crosshatch Adhesion Test described before. The coatings were all rated 5. 
The coated plates were tested for Gardner Impact strength with a 2 lb. 
weight and all of the coatings were rated at over 80 in.-lbs. In several 
cases, the metal plates cracked during testing, but not the polymeric 
coatings.