Process for controlling production of in-situ thermoplastic polyolefins and products

An improved gas-phase polymerization process for producing in-situ thermoplastic polyolefins in multiple reactors using high activity Ti/Al catalysts is provided. The improvement consists of developing a control parameter derived from eight integrated regions of the copolymer .sup.13 C NMR spectrum, defining the limits of the control parameter for the process, and operating the process to maintain the parameter within the defined limits. This is accomplished by adjusting the amount of ethylene fed to the secondary reactor and adjusting other process variables as required. Thermoplastic polyolefins, i.e., modified polypropylenes, having reduced hexane extractables and improved paint adhesion are also disclosed.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an improved gas-phase copolymerization 
process for producing in-situ thermoplastic polyolefins using high 
activity Ti/Al catalyst systems whereby polymerization conditions are 
controlled through the use of a control parameter. By monitoring the 
copolymer produced, ethylene feed and other process conditions are 
controlled and maintained within a specified range to produce polymers 
having improved properties. 
2. Description of the Prior Art 
A class of polypropylene which has enjoyed significant growth is propylene 
impact copolymer. These are two-phase materials consisting of a continuous 
phase of highly isotactic polypropylene and a dispersed phase of 
rubber-like ethylene-propylene copolymer. While these products can be 
produced by melt compounding, existing multi-reactor technology makes it 
possible to directly produce these products. This is conveniently 
accomplished by polymerizing propylene in a first reactor and discharging 
the polypropylene homopolymer from the first reactor into a secondary 
reactor where propylene and ethylene are copolymerized in the presence of 
the polypropylene. Gas-phase polymerizations of this type are described in 
the article by Ross, et al., "An Improved Gas-Phase Polypropylene 
Process," Ind. Eng. Chem. Prod. Res. Dev. 1985, 24, 149-154. This 
gas-phase technology has been extended to products containing 
significantly higher rubber/elastomer contents which are referred to as 
in-situ thermoplastic polyolefins (TPO). Copolymers of propylene and 
ethylene obtained utilizing Ziegler-Natta catalysts have been described in 
the prior art. U.S. Pat. No. 4,260,710 describes a process for producing 
propylene homopolymers and copolymers of propylene with other 
.alpha.-olefins utilizing Ziegler-Natta catalysts in a stirred vessel 
using catalyst components which can include a titanium halide and an 
aluminum alkyl. 
U.S. Pat. Nos. 4,454,299 and 4,455,405 describe processes for the 
preparation of block copolymers of propylene and ethylene in two reaction 
zones using Ziegler-Natta catalysts. In these processes, propylene is 
first polymerized in gas form in an initial reaction zone and the 
resulting homopolymer is then transferred to a second reactor where a 
mixture of ethylene and propylene are polymerized therewith. 
In U.S. Pat. No. 4,547,552 a process is disclosed to produce chemically 
blended propylene polymer compositions having ethylene contents from 3 to 
40 weight percent. The process comprises polymerizing propylene in a first 
stage with 0 to 5 mol percent of another olefin and, in a second stage, 
polymerizing propylene and ethylene or propylene, ethylene and another 
olefin in the presence of the reaction product from the first step. 
Rubbery propylene copolymer and crystalline ethylene polymer or copolymer 
are produced in this manner. 
U.S. Pat. No. 4,882,380 describes a gas-phase polymerization to produce 
products having an ethylene-propylene copolymer incorporated in a 
propylene homopolymer or copolymer matrix. This is accomplished by 
contacting propylene or another .alpha.-olefin in a first reactor using 
the prescribed catalyst and then passing the mixture to a second reactor 
where ethylene and propylene are polymerized to provide an 
ethylene-propylene copolymer. 
Other references dealing with multi-stage polymerizations of olefins 
include U.S. Pat. Nos. 4,338,424; 4,420,592; 4,582,878; 4,703,094; 
4,739,015; 4,740,550; 4,740,551; 4,814,377; 4,820,775; 4,902,483 and 
4,977,210. Whereas all of the aforementioned processes provide useful 
polymers, difficulties are encountered as ethylene contents are increased. 
The major problem is the stickiness of the product due to the increased 
rubber content and the increased content of "fines." In extreme cases, the 
product may even be heterogeneous and two distinct types of particles can 
be detected. Analysis of these particles has shown one to contain little 
or no ethylene incorporation and the other to contain virtually all of the 
ethylene incorporation. It would be highly advantageous if a process were 
available whereby polymerization conditions could be controlled to 
eliminate the aforementioned problems associated with heretofore known 
procedures. These and other advantages are realized with the present 
improved process. 
SUMMARY OF THE INVENTION 
The present process utilizes two reactors for the polymerization of 
propylene and ethylene to produce in-situ TPOs. In one highly useful 
embodiment of the invention, the polymerizations are carried out in the 
gas phase using fixed bed stirred reactors. In a first reactor propylene 
is homopolymerized at 50.degree. C. to 100.degree. C. and 250 psig to 650 
psig using a titanium catalyst and an organoaluminum cocatalyst. The 
homopolymer product produced in the first reactor is then fed to a second 
reactor where propylene and ethylene are copolymerized at 25.degree. C. to 
80.degree. C. and 100 psig to 500 psig. 
The improvement of the present invention which permits the preparation of 
in-situ TPOs having ethylene contents greater than 15 weight percent and 
improved physical properties is the ability to independently control and 
balance conditions in the first and second reactors. This is accomplished 
by calculating a control parameter, Q.sub.c, using the integrated peak 
areas of specified regions of the .sup.13 C NMR spectrum for these 
polymers and controlling the amount of ethylene to the secondary reactor 
and other process variables to maintain the value of the parameter within 
a defined range. This is conveniently achieved by monitoring the product 
produced, i.e., the modified polypropylene obtained from the second 
reactor, and comparing the actual value obtained for the product, Q.sub.A, 
with the control parameter or, more specifically, the limits defined 
therefor. 
In a preferred embodiment of the invention, the control parameter Q.sub.c 
is derived from eight integral regions of the .sup.13 C NMR spectrum as 
follows: 
##EQU1## 
where 
A=1.167R.sub.1 +0.75R.sub.2 +1.5R.sub.3 +1.5R.sub.4 +1.167R.sub.8 
B=0.667R.sub.1 +0.5R.sub.2 +R.sub.5 +R.sub.6 +R.sub.7 +0.667R.sub.8 
and R.sub.1 through R.sub.8 have the following peak assignments 
______________________________________ 
R.sub.1 37.9 PPM 
R.sub.2 37.5 PPM 
R.sub.3 33.2 PPM 
R.sub.4 31.2-30.9 PPM 
R.sub.5 30.4 PPM 
R.sub.6 30.0 PPM 
R.sub.7 27.4 PPM 
R.sub.8 24.9 PPM 
______________________________________ 
and the process conditions are maintained so that, Q.sub.A, the value of 
the product being produced, is from 0.65 to 1.0 and, more preferably, from 
0.75 to 0.98. 
Improved in-situ TPO products containing from 15 to 30 weight percent 
ethylene and having values for Q, where Q is obtained in accordance with 
the above equation, from 0.65 to 1.0 are also included in the invention. 
The products of the invention have significantly reduced hexane 
extractables and markedly improved paint adhesion.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention relates to an improved process for the polymerization 
of propylene and ethylene to produce in-situ TPOs, also referred to herein 
as modified polypropylenes, with increased ethylene contents. The process 
utilizes dual reactors connected in series for the polymerization. Whereas 
it is most advantageous to conduct both polymerizations in the gas phase, 
either the first or second reactor may be operated in a mode other than 
gas phase. 
In a first reactor, propylene is homopolymerized at a temperature from 
50.degree. C. to 100.degree. C. and pressure from 250 psig to 650 psig 
utilizing a titanium catalyst and an organoaluminum cocatalyst. More 
preferably, the temperature in the first reactor will be from 50.degree. 
C. to 90.degree. C. and the pressure will range from 300 psig to 450 psig. 
The highly isotactic homopolymer produced in the first reactor is directly 
fed to a second reactor which is maintained at 25.degree. C. to 80.degree. 
C. and 100 psig to 500 psig where propylene and ethylene are copolymerized 
in the presence of the homopolymer. The amount of ethylene employed in the 
second reactor is sufficient to produce a copolymer of propylene and 
ethylene with rubber-like characteristics. Ethylene levels sufficient to 
achieve 15-30 weight percent and, more preferably, 15-25 weight percent 
ethylene incorporation are employed. Polymerization in the second reactor 
is generally accomplished without additional catalyst; however, it may be 
advantageous, to introduce more catalyst to the second reactor. If more 
catalyst is employed, it can be the same as the catalyst used in the first 
polymerization or different. Preferably, the second polymerization reactor 
is operated at 40.degree. C. to 70.degree. C. and 100 psig to 350 psig. 
The use of dual or cascading reactors for the copolymerization of propylene 
and ethylene to produce impact copolymers is known. Similarly, gas-phase 
polymerizations utilizing stirred, fixed beds comprised of small polymer 
particles are also known. For additional information regarding gas-phase 
polymerizations and a schematic flow diagram of the process, reference may 
be made to the article by Ross, et al., in Ind. Eng. Chem. Prod. Res. 
Dev., 1985, 24: 149-154. 
A high activity titanium catalyst activated by contact with an 
organoaluminum cocatalyst is utilized to produce polymer particles for 
these polymerizations. The polymerizations are carried out in the 
substantial absence of liquid reaction medium and gas velocity within the 
stirred-bed is maintained below the onset of fluidization. Depending on 
their compositional makeup, gases can be recirculated through external 
heat exchangers for cooling or partially condensed. Cooled monomer is 
recirculated into the reactor and provides thermal control. Recirculated 
monomer vaporizes when it is introduced into the reactor so that 
polymerization occurs in the gas phase. In the preferred mode of 
operation, i.e., stirred, fixed-bed gas phase, the first and second 
reactors are fitted with spiral agitators to maintain a turbulent 
mechanically fluidized bed of polymer powder and prevent agglomeration. 
Each reactor typically has its own control system(s) and is capable of 
independent operation. In the usual conduct of the process, propylene and 
ethylene monomers are passed through desiccant beds prior to introduction. 
Means are usually provided to individually meter the propylene, ethylene, 
hydrogen for molecular weight control, catalyst and cocatalyst. This makes 
it possible to more readily control and maintain the desired reactor 
conditions. If desired, monomer may be injected into the recirculated gas 
stream for introduction into the system. Suitable controls are also 
provided to vary the pressure, temperature and compositional analysis to 
facilitate maintaining a constant environment in the reactor and/or to 
permit adjustment of conditions to bring the system into conformance. 
Residence times in both reactors are on the order of 1 to 4 hours. 
Highly isotactic polypropylene produced in the first reactor is introduced 
into a second reactor. This is facilitated by operating the primary 
reactor at a somewhat higher pressure than that maintained in the 
secondary reactor. Propylene, ethylene and hydrogen, as required, are 
metered into the second reactor so that ethylene and propylene are 
copolymerized in intimate admixture with the propylene homopolymer. In 
usual practice, there is sufficient catalyst present with the 
polypropylene to bring about polymerization in the second reactor and no 
further catalyst addition is required. Under certain circumstances, 
however, it may be advantageous to add additional catalyst/cocatalyst 
which can be the same or different as that used in the first reactor. 
The final modified polypropylene product, which is an intimate mixture of 
the highly isotactic homopolymer produced in the first reactor and 
rubber-like copolymer produced in the second reactor, is discharged into a 
pressure letdown vessel where low pressure recycle gas consisting largely 
of unreacted monomers is volatilized for recycling. The polymer can be 
processed to incorporate one or more additives and, if desired, 
pelletized. It is typically not necessary that the polymer exiting the 
second reactor be processed in a catalyst deactivation unit; however, for 
applications where extremely low levels of catalysts are required, this 
may be done. 
Ethylene contents of the polymers will be greater than 15 weight percent 
and can range up to 30 weight percent or above. More typically the amount 
of ethylene in the TPO will be from 15 to 25 weight percent. If desired, 
other .alpha.-olefins containing from 4 to 8 carbon atoms can be included 
in the polymerization and incorporated. Butene-1, pentene-1 and octene-1 
are useful comonomers for this purpose. 
Hydrogen is generally included in both reactors for control of molecular 
weight. The amount of hydrogen can range from 0.1 up to about 10 mole 
percent. More typically, hydrogen levels range from 0.1 to 5 mole percent 
in the primary reactor and from 1 to 10 mole percent in the secondary 
reactor. 
Small amounts of known modifiers or inhibitors may also be included in 
these polymerizations. These can include compounds such as oxygen, carbon 
monoxide, carbon dioxide, sulfur dioxide, glycol ethers, aliphatic and 
aromatic alcohols, carboxylic acids, sulfonic acids, water, and primary or 
secondary amines. The use of compounds of this type are disclosed in U.S. 
Pat. No. 4,739,015 and European Patent Application 86308952.0, published 
Jun. 10, 1987, Publication No. 0225099 and reference may be had thereto 
for additional detail. 
To effect polymerization of propylene and ethylene, a high activity 
Ziegler-Natta catalyst comprised of a titanium-containing catalyst 
component and organoaluminum cocatalyst component is necessarily employed. 
Such catalysts are known and are referred to herein as Ti/Al catalysts. 
These may include additional components, such as a support, modifying 
compound(s), magnesium and other metal compound(s), electron donating 
compound(s), and the like. 
Ti/Al catalyst systems utilized for the present process may be unsupported 
or they may be associated with conventional support materials. When 
supported, the support may be treated prior to incorporation of the 
titanium component. Conventional inorganic materials, such as silica, 
alumina, magnesium chloride, magnesium oxide, magnesium hydroxide and the 
like, can be used as supports. 
Titanium compounds used generally correspond to the formula Ti(OR).sub.n 
X.sub.m where R is aryl and/or alkyl, X is halogen, n is 1 to 4, m is 0 to 
3 with the proviso that m+n=4. Illustrative titanium compounds include: 
tetracresyl titanate, titanium tetrabutoxide, titanium tetranonolate, 
tetra 2-ethylhexyltitanate, tetra isobutyltitanate, tetra 
n-propyltitanate, tetra isopropyltitanate, titanium tetrachloride, 
titanium tetrabromide, methoxytitanium trichloride, ethoxytitanium 
trichloride, diethoxytitanium dichloride and the like. Trivalent compounds 
of titanium, such as titanium tribromide and titanium trichloride, may 
also be utilized. 
Examples of useful magnesium compounds which can be used in the preparation 
of the catalysts include: magnesium oxide, magnesium hydroxide, 
hydrotalcite, carboxylic acid salts of magnesium, alkoxy magnesiums, 
aryloxy magnesiums, alkoxy magnesium halides, aryloxy magnesium halides, 
magnesium dihalides, organomagnesium compounds and the like. Magnesium 
chloride (MgCl.sub.2) is widely used for the preparation of useful 
catalysts for polymerizing propylene and ethylene. 
Representative electron donors include: ethers, alcohols, esters, 
aldehydes, aliphatic (fatty) acids, aromatic acids, ketones, nitriles, 
amines, amides, urea, thiourea, isocyanates, azo compounds, phosphines, 
phosphites, thioethers, thioalcohols, etc. Specifically, there can be 
mentioned diethyl ether, di-n-butyl ether, diphenyl ether, ethylene glycol 
monomethyl ether, diethylene glycol dimethyl ether, methanol, ethanol, 
propanol, ethyl acetate, vinyl acetate, acetaldehyde, benzaldehyde, acetic 
acid, propionic acid, succinic acid, acrylic acid, benzoic acid, methyl 
ethyl ketone, benzophenone, acetonitrile, diethylamine, tributylamine, 
triethylphosphine, triphenylphosphine oxide, and triethylphosphite. 
The organoaluminum cocatalyst is usually an alkylaluminum or alkylaluminum 
halide and can include: trimethylaluminum, triethylaluminum, 
tri-n-propylaluminum, tri-n-butylaluminum, tri-i-butylaluminum, 
tri-n-hexylaluminum, tri-2-methylpentylaluminum, tri-n-octylaluminum, 
diethylaluminum monochloride, di-n-propylaluminum monochloride, 
di-i-butylaluminum monochloride, diethylaluminum monobromide, 
diethylaluminum monoiodide, diethylaluminum hydride, methylaluminum 
sesquichloride, ethylaluminum sesquichloride, ethylaluminum dichloride, 
and i-butylaluminum dichloride. Mixtures of these organoaluminum compounds 
can also be advantageously employed. 
In addition to the foregoing, other compounds may be used in the 
preparation of catalysts useful for gas-phase polymerization of propylene 
and ethylene. These compounds serve different functions and, in some 
cases, they may be multi-functional. They may act as activators or 
modifiers for the titanium compound or support or may themselves have 
catalytic or cocatalytic activity. Examples of such compounds include: 
silicon halides, such as silicon tetrachloride; boron halides, such as 
boron trichloride; silanes, such as hexyltrimethoxysilane, 
amyltriethoxysilane, isobutyltrimethoxysilane, trichlorosilane, 
dichlorosilane and dibromosilane; hexaalkyldisilazanes, such as 
hexamethyldisilazane; and vanadium compounds, such as vanadium oxychloride 
and vanadium tetrachloride. 
Ti/Al catalysts used for the gas-phase process of the invention are high 
activity catalysts, that is, they are capable of producing more than 5000 
grams copolymer per gram of catalyst. In a more preferred embodiment, 
Ti/Al catalysts capable of producing 7000 grams or more copolymer per gram 
of catalyst are used. The amount of titanium catalyst used with supported 
catalysts is generally such that residual Ti contents in the copolymer are 
less than 10 ppm and, more preferably, below 5 ppm. With unsupported Ti/Al 
catalysts, the amount of catalyst used is such that residual Ti is less 
than 55 ppm and, more preferably, less than 40 ppm. Useful Ti/Al catalysts 
which can be employed for the process are described in U.S. Pat. Nos. 
4,260,710; 4,309,521; 4,454,299; 4,547,552; 4,739,015; 4,814,377; 
4,820,775 and 5,037,789. 
In a particularly useful embodiment, highly active supported Ti/Al 
catalysts wherein the support is treated to remove or react surface 
hydroxyl groups prior to contacting with the titanium-containing compound 
are employed. Such pre-treatment or reaction of the support with a variety 
of materials makes it possible to produce catalysts which possess high 
activity for the polymerization of olefins in gas-phase processes. Such 
catalysts and their use for the homopolymerization of propylene are 
described in U.S. Pat. Nos. 4,950,631; 5,034,365; 5,051,388; 5,143,883; 
5,221,650; and 5,275,991. 
One preferred supported catalysts of the above type useful for the 
preparation of the propylene-ethylene copolymers in accordance with the 
invention, referred to as embodiment I, is obtained by: (a) treating 
silica to remove surface hydroxyl groups by calcining said silica in an 
inert atmosphere and treating with a hexaalkyldisilazane; (b) contacting 
said treated silica with (1) a modifying compound selected from the group 
consisting of silicon halides, boron halides, aluminum halides, alkyl 
silicon halides and mixtures thereof; and (2) at least one hydrocarbon 
soluble magnesium-containing compound selected from the group consisting 
of hydrocarbyloxy magnesiums, hydrocarbyloxymagnesium halides and mixtures 
thereof; said contacting steps (1) and (2) occurring in random order; (c) 
contacting said product of step (b) with at least one titanium-containing 
compound having the structural formula Ti (OR).sub.n X.sub.m, where R is 
aryl, alkyl or mixtures thereof; X is halogen; n is an integer of 1 to 4; 
m is 0 or an integer of 1 to 3; and the sum of m and n is 4; and (d) 
treating the product of step (c) with a titanium-containing compound 
having the structural formula TiX.sup.1.sub.p (OR.sup.1).sub.q, where 
X.sup.1 is halogen; R.sup.1 is aryl or alkyl; p is an integer 1 to 4; q is 
0 or an integer of 1 to 3; and the sum of p and q is 4, with the proviso 
that the titanium-containing compound of this step is not the same as the 
titanium-containing compound of step(c). Supported catalysts of this type 
are described in U.S. Pat. No. 4,950,631 which is incorporated herein by 
reference. 
In another preferred embodiment (embodiment II), the catalyst is obtained 
by treating silica to remove surface hydroxyl groups by calcining in an 
inert atmosphere and treating with a hexaalkyldisilazane and reacting said 
modified silica support having a selective distribution of reactive 
hydroxyl groups with a magnesium compound reactive with said surface 
hydroxyl groups, optionally reacting the thus obtained product with a 
silicon halide, alkyl silicon halide, boron halide or aluminum halide, 
further reacting the so-produced first material with a tetra-substituted 
organo halogen-free titanium compound wherein the organic moiety 
sterically hinders accessibility of said organo titanium compound to the 
reactive sites on the modified silica support and thereafter reacting the 
so-produced second material with a titanium halide. Supported catalysts of 
this type and procedures for their preparation are described in U.S. Pat. 
Nos. 5,143,883; 5,221,650; and 5,275,991 which are incorporated herein by 
reference. 
For yet another preferred embodiment (embodiment III), the catalyst is 
prepared by (a) contacting silica, in random order, with (1) at least one 
hydrocarbon soluble magnesium-containing compound; and (2) a first 
modifying compound selected from the group consisting of silicon halide; 
boron halides, aluminum halides and mixtures thereof followed by a second 
modifying compound selected from the group consisting of a silane of the 
formula SiH.sub.r X.sup.2.sub.s, where X.sup.2 is halogen; r is an integer 
of 1 to 3; and s is an integer of 1 to 3, with the proviso that the sum of 
r and s is 4, hydrogen halides having the structural formula HX.sup.3, 
where X.sup.3 is halogen, and mixtures thereof, said sequence of contact 
of silica with said components (1) and (2) being random; (b) contacting 
the product of step (a) with a first titanium-containing compound having 
the structural formula Ti(OR).sub.m X.sub.n, where R is hydrocarbyl or 
cresyl; X is halogen; m is an integer of 1 to 4; and n is 0 or an integer 
of 1 to 3, with the proviso that the sum of m and n is 4; and (c) 
contacting the product of step (b) with a second titanium-containing 
compound having the structural formula TiX.sup.1.sub.p (OR.sup.1).sub.q, 
where X.sup.1 is halogen; R.sup.1 is hydrocarbyl; p is an integer of 1 to 
4; q is 0 or an integer of 1 to 3, with the provisos that the sum of p and 
q is 4 and that said first titanium-containing compound and said second 
titanium-containing compound are different. Catalysts of this type are 
described in U.S. Pat. No. 5,034,365 which is incorporated herein by 
reference. 
For another preferred embodiment (embodiment IV), a highly useful catalyst 
is produced by (a) treating an inert inorganic support with 
hexamethyldisilazane to remove surface hydroxyl groups and heating at 
100.degree.-150.degree. C. for 1/2 to 3 hours; (b) contacting said treated 
inert inorganic support with a hydrocarbon soluble magnesium compound; (c) 
contacting said product of said step (b) with a modifying compound 
selected from the group consisting of silicon halides, boron halides, 
aluminum halides, hexaalkyldisilazanes and mixtures thereof; (d) 
contacting said product of said step (c) with a vanadium compound having 
the structural formula V(O).sub.s X.sup.1.sub.4-s, where X.sup.1 is 
halogen; and s is 0 or 1; a first titanium-containing compound having the 
structural formula TiX.sup.3.sub.p (OR.sup.3).sub.q, where X.sup.3 is 
halogen; R.sup.3 is hydrocarbyl; p is an integer of 1 to 4; and q is 0 or 
an integer of 1 to 3, with the proviso that the sum of p and q is 4 and, 
optionally, a second titanium-containing compound of the formula 
Ti(OR.sup.2).sub.n X.sup.2.sub.m, where R.sup.2 is hydrocarbyl; X.sup.2 is 
halogen; n is an integer of 1 to 4; and m is 0 or an integer of 1 to 3 
with the proviso that the sum of n and m is 4; and with the further 
proviso that if two titanium-containing compounds are used said first and 
said second titanium-containing compounds are not identical. 
A final preferred embodiment (embodiment V) utilizes a catalyst component 
obtained by (a) treating an inert inorganic support to a temperature of 
100.degree. C. to 150.degree. C. for 1/2 to 3 hours to remove surface 
hydroxyl groups; (b) contacting the treated inert inorganic compound with 
a hydrocarbon soluble magnesium compound; (c) contacting the product of 
said step (b) with a modifying compound selected from the group consisting 
of silicon halides, boron halides, aluminum halides, alkyl silicon 
halides, hexaalkyldisilazanes and mixtures thereof; and (d) contacting the 
product of said step (c) with a vanadium compound having the structural 
formula V(O.sub.2)X.sup.1.sub.4-s, is halogen and s is 0 or 1; a first 
titanium-containing compound having the structural formula TiX.sup.3.sub.p 
(OR.sup.3).sub.q, where X.sup.3 is halogen, R.sup.3 is hydrocarbyl, p is 
an integer of 1 to 4, and q is 0 or an integer of 1 to 3, with the proviso 
that the sum of p and q is 4 and, optionally, a second titanium-containing 
compound of the formula Ti(OR.sup.2).sub.n X.sup.2.sub.m, where R.sup.2 is 
hydrocarbyl, X.sup.2 is halogen, n is an integer of 1 to 4, and m is 0 or 
an integer of 1 to 3 with the proviso that the sum of n and m is 4; and 
with the further proviso that if two titanium-containing compounds are 
used said first and said second titanium-containing compounds are not 
identical. The catalysts of embodiments IV and V are described in U.S. 
Pat. No. 5,051,388 which is incorporated herein by reference. 
All of the supported titanium catalyst components of the aforementioned 
preferred embodiments I-V are utilized with one or more cocatalysts in the 
polymerization process. At least one cocatalytic agent which is an 
organoaluminum compound and, more preferably, an aluminum alkyl or 
alkylaluminum halide is combined with the titanium component. Further 
advantages are realized with certain of titanium components if a second 
cocatalyst silane component is also present. Useful silanes are 
hydrocarbylalkoxysilanes and have the general formula R'.sub.a 
(OR").sub.4-a Si where R' and R" are the same or different hydrocarbyl 
groups. 
Gas-phase stirred-bed polymerization processes are recognized for their 
reliability and ability be operated continuously for extended periods to 
produce large volumes of polymer. Because of the extended residence times 
for these processes, feed forward control is widely practiced to control 
reactor variables. However, as one or more of the process variables are 
controlled or adjusted to alter a particular property, this often has 
adverse affect on one or more of the other essential properties. With the 
present invention, it is now possible through the use of a derived 
parameter to control/adjust conditions in the primary and/or secondary 
reactors in a manner so that an improved balance of polymer properties and 
expanded property envelope can be obtained. Furthermore, it is possible to 
produce these improvements in a consistent manner and to minimize or 
eliminate the problems heretofore observed in the production of high 
ethylene content copolymers of this type. It is further possible with the 
present invention, after achieving conditions in the process which produce 
an optimum balance of properties, to maintain this balance of properties 
by making adjustments to compensate for unanticipated fluctuations in the 
system. 
Control of the process is accomplished using a control parameter, referred 
to as Q.sub.c, based on selected integrated peak areas of the .sup.13 C 
NMR spectrum for propylene-ethylene copolymers. After acceptable limits 
are defined for Q.sub.c,, the product obtained from the second reactor is 
analyzed and the actual value obtained for the product, referred to as 
Q.sub.A, and compared with the control parameter to determine 
conformance/nonconformance. Adjustments are made, as required, to the 
ethylene feed to the secondary reactor and, if necessary, to other process 
variables to bring the Q.sub.A into conformance with the limits defined 
for Q.sub.c. 
It will be understood by those skilled in the art that, if the overall 
(total) pressure in the second reactor is maintained at the same level, 
any change in ethylene pressure resulting from adjustments to the ethylene 
feed in response to the Q.sub.c will require a corresponding change in one 
or more of the other components present in the gas phase. A change in the 
partial pressure of ethylene will necessarily change the partial pressure 
of propylene, hydrogen and any other gas phase components at constant 
total pressure. The total pressure in the reactor may, on the other hand, 
be changed in response to changes in the amount of ethylene fed so that 
the partial pressures at the other gaseous components will remain 
unchanged. 
A number of control parameters may be developed depending on the particular 
.sup.13 C NMR peak areas used and the particular algorithm used to 
calculate the control. In general, however, the control parameter(s) used 
will be derived using all or some combination of the following .sup.13 C 
NMR peaks for solutions of ethylene-propylene copolymers generally 
accepted by the scientific and technical communities as corresponding to 
molecular structural features of these copolymers: 
______________________________________ 
CHEMICAL SHIFT (PPM) 
ASSIGNMENT 
______________________________________ 
45.6-47.5 S.sub..alpha..alpha. CH.sub.2 of PPP Triads! 
37.9 S.sub..alpha..GAMMA. CH.sub.2 in PEP! 
37.5 S.sub..alpha..delta..sup.+ CH.sub.2 in EEEP and PEEP! 
33.2 T.sub..GAMMA..GAMMA..sup.+ CH in EPE! 
31.2-30.9 T.sub..beta..GAMMA..sup.+ CH in PPE! 
30.4 S.sub..GAMMA..delta..sup.+ CH.sub.2 in PEEP! 
30.0 S.sub..delta..delta..sup.+ CH.sub.2 in EEEE! 
29.0-28.4 T.sub..beta..beta. CH in PPP! 
27.4 S.sub..beta..GAMMA..sup.+ CH.sub.2 in EEEP and PEEP! 
24.9 S.sub..beta..beta. CH.sub.2 in PEP! 
21.6-19.5 P CH.sub.3 in all P Triads! 
______________________________________ 
The eleven .sup.13 C NMR peaks listed above have been widely used in the 
literature to calculate sequential distributions of the six theoretically 
possibly triads, three dyads, and the overall compositions of copolymers 
of ethylene and propylene. Details regarding the use of these .sup.13 C 
NMR peak areas for the calculation of composition and monomer sequence 
distributions in copolymers and problems associated with the resolution 
and determination thereof are available in the text of J. C. Randall, 
Polymer Sequence Determination, Academic Press (1977) or the paper by the 
same author in JMS--Rev. Macromol Chem. Phys., C29 (2 and 3), 201-317 
(1989). Whereas the various methods described by Randall involve the 
addition and subtraction of numerous peak areas which can result in the 
summation of errors, the method of the invention uses fewer peaks. 
Determinations will, of course, depend on the accuracy of the individual 
integrals and resolution of the peaks in the spectrum. 
In one highly useful embodiment of the invention, one or more control 
parameters derived from eight of the above-identified peak areas, 
identified as R.sub.1 -R.sub.8, are utilized. The peaks R.sub.1 through 
R.sub.8 correspond to the following chemical shifts: R.sub.1 37.9 PPM; 
R.sub.2 37.5 PPM; R.sub.3 33.2 PPM; R.sub.4 31.2-30.9 PPM; R.sub.6 30.4 
PPM; R.sub.6 30.0 PPM; R.sub.7 27.4 PPM and R.sub.8 24.9 PPM. In 
identifying and resolving the aforementioned peak areas, the methyl peak 
due to isotactic PPPPP pentads is used as a chemical shift reference line 
and is set to 21.78 PPM. 
In a highly useful and preferred embodiment of the invention, the control 
parameter Q.sub.c is derived from the eight integral regions of the 
.sup.13 C NMR spectrum in accordance with the equation 
##EQU2## 
wherein 
A=1.167R.sub.1 +0.75R.sub.2 +1.5R.sub.3 +1.5R.sub.4 +1.167R.sub.8 
B=0.667R.sub.1 +0.5R.sub.2 +R.sub.5 +R.sub.6 +R.sub.7 +0.667R.sub.8 
where R.sub.1 through R.sub.8 correspond to the previously identified peak 
areas. When Q.sub.c conforms to the above definition, the defined limits 
for Q.sub.c for the process will range from 0.65 to 1.0 and, more 
preferably, from 0.75 to 0.98. In the event the actual value obtained for 
Q.sub.A drops below the 0.65 minimum limit, the ethylene feed to the 
secondary reactor would be decreased and temperature increased, for 
example, to maintain the desired level of total ethylene in the copolymer. 
Adjusting the ethylene feed will change the ratio of the partial pressures 
of the gaseous components in the reactor. Other process conditions and 
feed rates may but are not necessarily changed to bring the system, i.e., 
process and copolymer composition, into conformance. When Q.sub.A exceeds 
the maximum permissible limit of 1.0, the ethylene feed to the secondary 
reactor would be increased. Additionally, the temperature in the second 
reactor could be decreased in order to maintain the desired total level of 
ethylene in the copolymer. 
Whereas Q.sub.c is by itself a convenient and highly useful parameter for 
controlling the reaction conditions in the primary and secondary reactors, 
it may also be utilized in conjunction with other parameters obtained 
using other combinations of the characteristic .sup.13 C NMR peaks. It 
will be appreciated by those skilled in the art that if comonomers other 
than ethylene are employed, peak assignments will have to be modified to 
correspond to the analogous structural features. For propylene-butene-1 
copolymers, for example, the structural features for ethyl groups rather 
than methyl groups will be used. When employed herein, the terms Q, 
Q.sub.c and Q.sub.A are all determined using the formula A/B, unless 
otherwise specified. 
In addition to being used to control polymerization conditions, the 
above-defined parameters also describe and differentiate subtle 
differences in the polymer properties. An illustration of the control of 
polymer properties includes the ability to obtain improved impact 
properties at temperatures as low as -40.degree. C. and -50.degree. C. at 
high rubber contents. Also, by judicious choice of catalyst and reactor 
conditions it is possible to vary flexural modulus. In this manner, the 
stiffness/impact balance can be readily tailored to meet the specific 
needs of an end-user's application. With the process it is also possible 
to obtain highly desirable and efficient dispersion of the rubber phase so 
that improved levels of heat distortion temperatures can be obtained. Even 
with materials having relatively high rubber contents only modest changes 
in heat deflection temperatures occur. 
Thermoplastic polyolefins produced using the present process and having Q 
values within the previously described ranges have a significantly lower 
hexane extractable fraction which renders these products highly useful for 
Food and Drug Administration (FDA) compliant applications. More 
specifically, it is possible using the process of the invention to readily 
and consistently produce copolymers which meet the extractables 
requirements of 21 CFR 1771.1520(c)3.1a and 21 CFR 1771.1520(c) 3.2a. The 
first regulation is directed to usage in articles that contact food except 
for articles used for packing or holding food during cooking and requires 
a maximum extractables fraction (expressed in weight percent by weight of 
polymer) in n-hexane at 50.degree. C. of 5.5 percent. The latter 
regulation which applies to articles used for packing or holding food 
during cooking has a maximum n-hexane extractables limit of 2.6 percent at 
50.degree. C. With thermoplastic polyolefin products obtained using prior 
art processes, and especially with products obtained by physically 
blending polypropylene with ethylene-propylene copolymers, it has not been 
possible to consistently meet these extractables limits, particularly the 
more stringent requirements of 21 CFR 177.1520(c)3.2a. This is 
particularly so with higher rubber, i.e., higher ethylene, content 
products. With the products of the invention, and particularly with 
products prepared in stirred, fixed-bed gas phase reactors using the 
preferred highly active supported Ti/Al catalysts wherein the support is 
treated to remove or react surface hydroxyl groups before contacting with 
the titanium compound, it is possible to consistently meet and exceed 
these extractables limits even with high rubber content products. This is 
believed to be the result of the more efficient ethylene utilization 
achieved by controlling the process using the above-defined control 
parameter. 
In addition to having reduced hexane extractables, the modified 
polypropylene products produced by the invention also have been found to 
have significantly improved paint adhesion compared to reactor produced 
TPOs which have Q values outside the prescribed ranges or TPOs obtained by 
physically blending polypropylene and ethylene-propylene rubbers. As a 
result, TPO resins produced by the inventive process are highly useful for 
automotive applications where good paint adhesion and resistance of 
painted surfaces to abrasion are essential. 
To better understand the operation of the process for the production of 
high ethylene content in-situ TPOs which are nonsticking and free-flowing, 
the following examples are provided for illustration. Parts and 
percentages are on a weight basis unless otherwise indicated. 
EXAMPLE I 
Preparation of Titanium Catalyst 
A supported titanium-containing catalyst having the following loading was 
prepared: 
3.0 mmole ROMgCl/lb silica 
4.2 mmole SiCl.sub.4 /lb silica 
0.5 mmole Ti(OR).sub.4 /lb silica 
18 mmole TiCl.sub.4 /lb silica 
For the catalyst preparation hexamethyldisilazane-treated silica (Crosfield 
EP-10) containing 4% carbon by analysis on silica was charged to a vessel 
and heated for 8 hours with a nitrogen purge while heating at a 
temperature of 138.degree.-149.degree. C. The treated silica was cooled to 
26.5.degree. C. under 30 psi N.sub.2 and 2-methyl-1-pentyloxymagnesium 
chloride added with stirring. The mixture was heated at 90.5.degree. C. 
under a nitrogen purge for 2-3 hours and then cooled to 35.degree. C. 
under 15 psi N.sub.2 heptane and silicon tetrachloride solution (35 wt. % 
in heptane) were then added. The SiCl.sub.4 was added at a controlled 
rate. When the addition was complete, the mixture was heated to 
48.9.degree. to 54.4.degree. C. and maintained for 1 hour. The mixture was 
then cooled and the solids permitted to settle for 2 hours. The bulk of 
the liquid was siphoned off and fresh heptane added with stirring for 15 
minutes. This mixture was permitted to settle for 2 hours and the 
siphoning repeated. Heptane was again added while stirring followed by the 
addition of titanium cresylate solution (40% in heptane) and then titanium 
tetrachloride. The mixture was heated and maintained at 
100.degree..+-.12.degree. C. for 2 hours. After cooling to below 
88.degree. C., heptane was added and agitation was stopped. The reactor 
was cooled to below 65.degree. C. and the mixture allowed to settle for 2 
hours. The liquid was siphoned off and fresh heptane added followed by 
stirring for 15 minutes and 1 hour settling. This procedure was repeated 4 
more times. The catalyst was then dried at 99.degree..+-.12.degree. C. 
with a nitrogen purge until all the heptane was removed. 
Polymerization of Propylene and Ethylene 
The ability to utilize the control parameter derived from the .sup.13 C NMR 
spectrum in accordance with the equation provided for Q.sub.c in a 
two-reactor gas-phase operation is demonstrated by the following 
experiment whereby propylene is polymerized in a first reactor and the 
product produced therein is fed to the second reactor where ethylene and 
propylene are copolymerized in the presence of the homopolymer. Reactor 
conditions and/or feed rates were selected for these runs so that the 
control parameter was nominally maintained within the broad range for 
Q.sub.c of 0.65 to 1.0. 
Two conventional 800 liter gas-phase polymerization reactors, each equipped 
with a stirrer to maintain turbulent mechanical fluidization of the 
polymer powder within, were connected so that polymer from the first 
(primary) reactor was introduced into the second (secondary) reactor. 
Propylene and hydrogen were continuously metered at controlled rates to 
the first reactor. Titanium catalyst and two cocatalysts were 
independently metered. The first cocatalyst was triethylaluminum which was 
introduced as a 25% solution in heptane. The second cocatalyst, 
isobutyltrimethoxysilane, was introduced as a 15% solution in heptane. The 
catalyst and cocatalyst agents were fed at rates to maintain the specified 
triethylaluminum/silane/titanium ratio. Ethylene, propylene and hydrogen 
were continuously metered at controlled rates to the second reactor. An 
alcohol modifier was also added. No catalyst or cocatalyst was added to 
the second reactor. 
The actual value, Q.sub.A, obtained for the modified polypropylene produced 
under steady state conditions is indicated in Table I. Operating 
conditions employed in the primary and secondary reactors to achieve and 
maintain production of polymer having that Q.sub.A value are also provided 
in Table I. 
TABLE I 
______________________________________ 
RUN 1 RUN 2 RUN 3 
______________________________________ 
Q.sub.A 0.80 0.71 0.64 
Primary Reactor: 
Alkylaluminum/silane/titanium 
100/10/1 150/10/1 150/10/1 
ratio 
Alkylaluminum Solution Feed 
16.2 16.2 16.6 
Rate (oz/hr) 
Propylene Feed Rate (lbs/hr) 
242.7 160.9 243.4 
H.sub.2 Feed Rate (SCFH) 
5.44 4.03 5.70 
Temperature (.degree.C.) 
77 77 77 
Pressure (psig) 401.6 400.0 402.0 
Recycle (GPM) 2.08 1.12 2.43 
Secondary Reactor: 
Propylene Feed Rate (lbs/hr) 
71.9 44.4 59.1 
Ethylene Feed Rate (lbs/hr) 
91.6 98.7 162.1 
Hydrogen Feed Rate (SCFH) 
4.96 13.83 11.19 
Alcohol Feed Rate (oz/hr) 
140.7 55.1 50.0 
Temperature (.degree.C.) 
54 60 60 
Pressure (psig) 199.8 200.0 200.1 
Liquid Recycle (GPM) 
1.83 1.79 2.95 
Gas Recycle (SCFH) 
5.29 4.52 7.69 
______________________________________ 
The polymer powder obtained from the second reactor was free-flowing and 
non-sticky. Bulk density, mean particle size and amount of fines were 
determined for the powders and are reported in Table II. The powders were 
processed in an extruder where conventional additives were incorporated 
into the melt and then pelletized. The modified polypropylene was analyzed 
and physical properties determined. Results are listed in Table II. The 
notation N.D. in the tables indicates that a value was not determined for 
the product. 
TABLE II 
______________________________________ 
PRODUCT OF 
RUN 1 RUN 2 RUN 3 
______________________________________ 
Bulk Density (lb/ft.sup.3) 
19.1 20.7 20.1 
Mean Particle Size (.mu.M) 
1028 1256 1242 
% Fines &lt; 180 .mu.M 
0.2 0 0.1 
% Fines &lt; 350 .mu.M 
4.8 0.45 0.9 
Ethylene Content 16.0 20.6 23.1 
(wt. %) 
Ti (ppm) 6.9 4.8 4.0 
Al (ppm) 406 400 297 
Cl (ppm) 49 32 35 
Melt Flow Rate 2.91 2.09 2.16 
(pellet; dg/min) 
Melt Temperature 161.26 N.D. N.D. 
(DSC; .degree.C.) 
Tensile Yield (psi) 
2382 2084 N.D. 
Elongation Yield (%) 
17.8 17.8 N.D. 
Flexural Modulus (psi) 
84200 82400 N.D. 
______________________________________ 
EXAMPLE II 
Another series of polymers were prepared utilizing a supported 
titanium-containing catalyst wherein the silica support was treated prior 
to contacting with the titanium moiety. For these runs the supported 
titanium catalyst was prepared in accordance with the procedure of Example 
I except that the catalyst loading was as follows: 
5.5 mmole ROMgCl/lb silica 
5.5 mmole SiCl.sub.4 /lb silica 
0.6 mmole Ti(OR).sub.4 /lb silica 
18 mmole TiCl.sub.4 /lb silica 
For the four polymerizations, Q.sub.c was maintained within the preferred 
range of 0.75-0.98. The polymerizations were carried out following the 
procedure described in Example I. The Q.sub.A value of the modified 
polypropylene product and reactor conditions are set out in Table III. 
Properties of the in-situ thermoplastic polyolefins produced are 
identified in Table IV. 
TABLE III 
______________________________________ 
RUN 1 RUN 2 RUN 3 RUN 4 
______________________________________ 
Q.sub.A 0.83 0.85 0.81 0.76 
Primary Reactor: 
Alkylaluminum/silane/ 
100/10/1 100/10/1 100/10/1 
100/10/1 
titanium ratio 
Alkylaluminum Feed 
15 12.7 16.5 14 
Rate (oz/hr) 
Propylene Feed 
309 314.6 326.7 305.3 
Rate (lbs/hr) 
H.sub.2 Feed Rate (SCFH) 
3.5 2.5 3.1 2.73 
Temperature (.degree.C.) 
77 77 77 77 
Pressure (psig) 
399.3 399 395 403 
Recycle (GPM) 
3.4 4.27 3.53 3.56 
Secondary Reactor: 
Propylene Feed 
136.5 71.5 162.5 134.5 
Rate (lbs/hr) 
Ethylene Feed 
180 144.5 193 186.5 
Rate (lbs/hr) 
Hydrogen Feed 
0.3 3.4 0 0 
Rate (SCFH) 
Alcohol Feed 6.85 3.45 0 1.05 
Rate (oz/hr) 
Temperature (.degree.C) 
65.5 65.5 65.5 65.5 
Pressure (psig) 
219 220.5 222 220.5 
Liquid Recycle (GPM) 
1.45 1.45 1.85 1.75 
Gas Recycle (SCFH) 
0 0 0 0 
______________________________________ 
TABLE IV 
______________________________________ 
PRODUCT OF 
RUN 1 RUN 2 RUN 3 RUN 4 
______________________________________ 
Bulk Density (lb/ft.sup.3) 
22.3 19.8 19.9 22.5 
Mean Particle Size (.mu.M) 
1236 1365 1296 1323 
% Fines &lt; 90 .mu.M 
0.1 0 0 0.1 
Ethylene Content 
16.0 17.0 19.4 19.9 
(Wt. %) 
Ti (ppm) 2.6 2.3 2.5 1.7 
Al (ppm) 209 179 201 165 
Cl (ppm) 28 24 24 19 
Melt Flow Rate (pellet; 
1.18 1.81 1.76 1.12 
dg/min) 
Melt Temperature 
161.8 161.2 161.2 161.8 
(DSC; .degree.C.) 
Tensile Yield (psi) 
2181 2120 1910 1742 
Elongation Yield (%) 
34 27 27 34 
Flexural Modulus (psi) 
79300 75400 63500 60500 
______________________________________ 
The in-situ thermoplastic polyolefins produced in the foregoing examples 
are intimate mixtures of highly isotactic polypropylene produced in the 
first reactor and the rubber-like propylene-ethylene copolymer produced in 
the second reactor. By use of defined parameters to control the process 
conditions, it is possible to produce high ethylene content products which 
have desirable physical characteristics without operational problems. 
The polymers produced in accordance with the process of the invention using 
control values in the defined Q.sub.c range have a useful balance of 
structural characteristics and physical properties. It is apparent that 
the property envelope of these copolymers can be varied by adjusting 
operating conditions so that the value of Q will be changed, e.g., by 
changing the ethylene feed to the second reactor and, if necessary, other 
process conditions. To operate the system so as to obtain a lower value 
for Q.sub.A, the 
amount of ethylene in the second reactor would be increased. If it is 
desired to increase the Q.sub.c target to a higher value, adjustments 
would be made to decrease the amount of ethylene fed to the secondary 
reactor. In line process changes of this type are readily accomplished 
during continuous operation to bring the system into conformance with 
Q.sub.c target or to vary Q.sub.c within the defined limits in order to 
vary structural characteristics and/or physical properties of the in-situ 
TPO produced. 
EXAMPLE III AND COMATIVE EXAMPLE A 
To demonstrate the reduced extractables content of the thermoplastic 
polyolefins produced using the process of the invention, two copolymer 
products having comparable ethylene contents and melt flow rates were 
produced following the polymerization procedure described in Example I. 
The first ethylene-propylene copolymer, referred to as EX III, was 
prepared in accordance with the invention using a supported Ti/Al catalyst 
system as described in Example I and maintaining Q within the prescribed 
range. The comparative propylene-ethylene copolymer, referred to as CEX A, 
was produced using a supported Ti/Al catalyst of the type described in 
British Patent 2109800B and had a Q value outside the prescribed range. 
While the physical properties of the two products were comparable, the 
hexane extractables (determined using n-hexane at 50.degree. C.) was three 
times higher for the comparative copolymer and did not meet the FDA 
requirements per 21 CFR 177.1520(c)3.2a for use in articles used for 
packing or holding food during cooking. Physical properties of the two 
products, along with their Q values, ethylene contents, melt flow rates 
and hexane extractables are set forth in the table which follows. 
______________________________________ 
EX III CEX A 
______________________________________ 
Q 0.79-0.81 0.61-0.62 
Ethylene Content (Wt. %) 
9.1 9.7 
Melt Flow Rate (pellet; dg/min) 
4.2 5.0 
Hexane Extractables (Wt. %) 
1.5 4.7 
Flexural Modulus (psi) 
144100 145000 
Gardner Impact @ 23.degree. C. (in-lbs) 
451 350 
Notched Izod @ 23.degree. C. (ft-lbs/in) 
2.8 2.2 
Unnotched Izod @ -18.degree. C. (ft-lbs/in) 
23 20 
______________________________________ 
EXAMPLES IV-V AND COMATIVE EXAMPLES B-E 
To further demonstrate the improved copolymer products obtainable from the 
present process, two inventive products (EX IV and EX V) of varying 
ethylene content, melt flow rate, and Q value were prepared and compared 
with a product with a Q value outside the prescribed range (CEX B), a 
physically blended product (CEX C) and two commercially available 
reactor-produced TPOs (CEX D and CEX E). The products were compared with 
regard to their paint adhesion characteristics by evaluating painted 
copolymer specimens using two test procedures developed for the automotive 
industry. The first procedure, General Motors Test Procedure 9911P, 
determines the resistance of paint to be removed from a TPO substrate 
material using a Taber Abraser Model 5150 fitted with a scuffing 
attachment. In this test the percent paint removal during 100 cycles is 
reported per the procedure. Another procedure, Ford Laboratory Test Method 
BI 107-5, is a thermal shock test for paint adhesion designed to simulate 
the wet blast produced by vehicle wash equipment. In this test, the 
painted specimens prepared and conditioned in accordance with the 
procedure are examined after a steam blast for a minimum of 30 seconds and 
samples showing any loss of paint adhesion or blushing are noted. Results 
are reported by giving the number of samples passing versus the total 
number tested. For all of the evaluations, the prescribed specimens were 
coated first with an adhesion promotor (Bee HP 210584 HS), then with the 
base coat (DuPont 542-DF716 White) and finally with a clear coat (DuPont 
RK 3939). Results obtained using the copolymers of the invention and the 
comparative products are set forth in Table V. In addition to results of 
the paint tests, the Q value, ethylene content, melt flow rate and 
flexural modulus are reported for each of the products. 
TABLE V 
__________________________________________________________________________ 
EX IV 
EX V 
CEX B 
CEX C 
CEX D 
CEX E 
__________________________________________________________________________ 
Q 0.79 
0.82 
0.57 
0.61 
0.54 
0.61 
Ethylene Content (Wt. %) 
11.5 
14.3 
14.1 
17.4 
14.0 
15.2 
Melt Flow Rate (pellet: dg/min) 
11.0 
10.8 
10.5 
11.2 
11.5 
10.4 
Flexural modulus (psi) 
100,000 
84,000 
102,000 
106,000 
109,000 
84,000 
Taber Test (% paint removed) 
0.8 0.1 21.7 
74.8 
39.8 
27.2 
Thermal Shock Test 
20/20 
20/20 
14/20 
8/20 
11/20 
12/20 
(Pass/Total tested) 
__________________________________________________________________________ 
It is apparent from the data provided in Table V that superior paint 
adhesion is obtained with the products of the invention. Extremely low 
paint removal values were observed for Examples IV and V and there were no 
failures in the thermal shock test. With the product having a Q value 
outside the prescribed range, paint adhesion was unacceptable. Also, 
unacceptable results were observed with the physically blended product CEX 
C and with the two commercial products (CEX D and CEX E).