Thermoplastic elastomeric blend of monoolefin copolymer rubber, amorphous polypropylene resin and crystalline polyolefin resin

This invention relates to a thermoplastic elastomer composition. 
Thermoplastic elastomers are materials which can be processed and 
fabricated by methods used for thermoplastics and do not require any cure 
in the shaped state to develop elastomeric properties, unlike ordinary 
elastomers which require cure or vulcanization. Thermoplastic elastomers 
can be reprocessed since they remain thermoplastic, and therefore scrap 
and rejects can be recycled, unlike conventional elastomers which are 
thermoset once they are cured and cannot be reworked. Thermoplastic 
elastomers therefore combine in an economical manner the processing 
advantages of a thermoplastic with certain desirable physical properties 
of a cured elastomer. 
Thermoplastic elastomers based on blends of saturated or low unsaturation 
monoolefin copolymer rubber (EPM or EPDM type rubber) with crystalline 
polyolefin resin are known. Typically they are made by dynamically 
partially curing the blend of rubber and resin (see, for example, U.S. 
Pat. No. 3,806,558, Fischer, Apr. 23, 1974; see also Fischer U.S. Pat. 
Nos. 3,758,643 issed Sept. 11, 1973, 3,835,201 issued Sept. 10, 1974, and 
3,862,106 issued Jan. 21, 1975, and U.S. Pat. No. 4,031,169, Morris, June 
21, 1977. Shaped articles having elastomeric properties can be fabricated 
from the resulting thermoplastic blends without further cure. It has been 
desired to improve the processing behavior of such thermoplastic 
elastomers. 
U.S. Pat. No. 3,564,080, Pedretti et al, Feb. 16, 1971, discloses extending 
or diluting vulcanizable EPM or EPDM type rubber compositions with 
amorphous polypropylene for the purpose of improving the processability; 
the compositions are vulcanized in the conventional manner to a thermoset, 
unprocessable state. 
U.S. Pat. No. 4,076,669, Harper, Feb. 28, 1978, discloses extending certain 
hydrogenated SBR rubbery block copolymers with amorphous polypropylene to 
provide good tensile and flow properties. 
In accordance with the present invention, it has now been found that 
improved thermoplastic elastomers having good processing characteristics 
and desirable physical properties are obtained by blending: 
A. a monoolefin copolymer rubber; 
B. an amorphous non-elastomeric polypropylene resin or amorphous 
non-elastomeric resinous copolymer of propylene with another monoolefin; 
and 
C. a crystalline polyolefin resin; 
the said ingredients A, B and C being present in the following proportions; 
expressed as percent by weight based on the total weight of A, B and C: 
15 to 80% of A 
5 to 45% of B 
15 to 80% of C 
These proportions fall within a trapezoid a b c d having the following 
triangular coordinates, expressed as weight percent, based on the sum of 
the weights of A, B and C: 
______________________________________ 
a b c d 
______________________________________ 
A 80 40 15 15 
B 5 45 45 5 
C 15 15 40 80 
______________________________________ 
Preferred proportions of A, B and C are: 
20 to 50% of A 
5 to 35% of B 
15 to 75% of C 
These fall within the trapezoid a b' c' d' represented by the following 
triangular coordinates: 
______________________________________ 
a b' c' d' 
______________________________________ 
A 80 50 20 20 
B 5 35 35 5 
C 15 15 45 75 
______________________________________ 
In the accompanying drawing the single FIGURE is a graph, on triangular 
coordinates, representing the proportions of the three polymeric 
ingredients in the compositions of the invention. In the graph, the 
trapezoid a b c d represents the broad proportions set forth above, while 
the trapezoid a b'c'd' represents the preferred proportions.

Particularly valuable compositions of the invention further include up to 
70 percent by weight, preferably from 5 to 30 percent by weight, of 
extender oil, based on the sum of the weights of the polymeric components 
A, B and C. 
The blend may be subjected to a dynamic partial curing step as in the 
above-mentioned Fischer U.S. Pat. No. 3,806,558 but this is not essential. 
If a dynamic partial curing step is utilized it may be carried out on the 
monoolefin copolymer rubber component A above before blending with the 
other two polymeric components B (the amorphous polypropylene homopolymer 
or copolymer resin) or C (the crystalline polyolefin resin), or the 
dynamic curing step may be carried out after mixing the monolefin 
copolymer rubber component A with some or all of either or both of the two 
other polymeric components B and C. In any event, it will be noted that 
the present blend is distinguished from the conventional Fischer-type of 
thermoplastic elastomer in that component B, the amorphous non-elastomeric 
polypropylene homopolymer or copolymer resin, is included in the final 
blend, whether a dynamic curing step is undertaken or not. 
The monoolefin copolymer rubber A employed in the blend of the invention is 
an amorphous, random, elastomeric copolymer of two or more monoolefins, 
with or without a copolymerizable polyene. Usually two monoolefins are 
used, but three or more may be used. Ordinarily one of the monoolefins is 
ethylene while the other is preferably propylene. However, other 
alphamonoolefins may be used including those of the formula CH.sub.2 
.dbd.CHR where R is an alkyl radical having for example one to 12 carbon 
atoms (e.g., butene-1, pentene-1, hexene-1, 4-methylpentene-1, 
5-methylhexene-1, 4-ethylhexene-1, etc.). While the monoolefin copolymer 
rubber may be a saturated material, as in ethylene propylene binary 
copolymer rubber ("EPM"), it is ordinarily preferred to include in the 
copolymer a small amount of at least one copolymerizable polyene to confer 
unsaturation on the copolymer ("EPDM"). Although conjugated dienes such as 
butadiene or isoprene may be used for this purpose (British Pat. No. 
983,437, Belgian Pat. No. 736,717, Sumitomo Chemical Co., Jan. 29, 1970), 
in practice it is usual to employ a non-conjugated diene, including the 
open-chain non-conjugated diolefins such as 1,4-hexadiene (U.S. Pat. No. 
2,933,480 Gresham et al., Apr. 19, 1960) or a cyclic diene, especially a 
bridged ring cyclic diene, as in dicyclopentadiene (U.S. Pat. No. 
3,211,709, Adamek et al., Oct. 12, 1965), or an alkylideneorbornene as in 
methylenenorbornene or ethylidenenorbornene (U.S. Pat. No. 3,151,173, 
Nyce, Sept. 29, 1964), as well as cyclooctadeiene, methyltetrahydroindene, 
etc. (see also such U.S. Pat. Nos. as 3,093,620 and 3,093,621; also 
3,538,192 col. 6 line 49 to col. 7, line 51). The polyenes employed are 
not limited to those having only two double bonds, but include those 
having three or more double bonds. Typically, conventional monoolefin 
copolymer rubber has a Brookfield viscosity in excess of 5,000,000 at 
375.degree. F., and a Mooney viscosity, of at least 20 ML-4 at 212.degree. 
F. 
The crystalline polyolefin resin C used to make the blend of the invention 
is a solid, high molecular weight resinous plastic material made by 
polymerizing such olefins as ethylene, propylene, butene-1, pentene-1, 
4-methylpentene, etc., in conventional manner. Thus, such crystalline 
polyolefins as polyethylene (either of the low density e.g., 0.910-0.925 
g/cc, medium density 0.926-0.940 g/cc or high density e.g., 0.941-0.965 
type) may be used, whether prepared by high pressure processes or low 
pressure processes, including linear polyethylene. Polypropylene is a 
preferred polyolefin plastic, having highly crystalline isotactic and 
syndiotactic forms. Frequently the density of polypropylene is from 0.800 
to 0.980 g/cc. Largely isotactic polypropylene having a density of from 
0.900 to 0.910 g/cc may be mentioned particularly. Crystalline block 
copolymers of ethylene and propylene (which are plastics distinguished 
from amorphous, random ethylene-propylene elastomers) can also be used. 
Included among the polyolefin resins are the higher alpha-olefin modified 
polyethylenes and polypropylenes (see "Polyolefins", N. V. Boenig, 
Elsevier Publishing Co., N.Y., 1966). 
Component B, the amorphous, non-elastomeric polypropylene homopolymer or 
amorphous, non-elastomeric copolymer of propylene with another monoolefin 
(e.g., ethylene), is characterized by low degree of isotactic or 
syndiotactic blocks of said propylene or alpha-olefin copolymer. Unlike 
crystalline polyolefins such as crystalline polypropylene, such amorphous 
polymers or copolymers are generally soluble below 100.degree. C. with 
most aliphatic, aromatic, and halogenated hydrocarbons. 
Whereas largely isotactic crystalline polypropylene has a density of from 
0.900 to 0.910 g/cc, amorphous polypropylene has a density below 0.900 
g/cc, usually within a range 0.82 to 0.88 g/cc. 
Amorphous polypropylene is generally obtained as a byproduct in the 
production of crystalline isotactic polypropylene. Whereas crystalline 
isotactic polypropylene is not soluble except at high temperatures (above 
about 120.degree. C.) in any organic solvents, the amorphous polypropylene 
will dissolve. 
Amorphous polypropylene is usually obtained by extracting the mixture of 
crystalline isotactic polypropylene and amorphous polypropylene produced 
by typical polymerization catalysts with an appropriate solvent. The 
amorphous polypropylene is that fraction which is soluble in the 
extraction solvent. 
Low viscosity is one characterizing property of conventional amorphous 
polypropylene obtained by extraction from crystalline polypropylene. 
Viscosity ranges for several grades are summarized in Table A. 
Table A 
__________________________________________________________________________ 
Amorphous Polypropylene or Propylene-Ethylene Copolymer Properties 
Ring & Ball GPC, 
Softening 
Brookfield 
Intrinsic Polystyrene 
Number 
Weight 
Density 
Point Viscosity 375.degree. F. 
Viscosity 
Relative 
equivalent 
average 
average 
Trademark g/cc .degree.F. 
cps dl/g Viscosity 
peaks, mol. wt. 
mol. 
mol. 
__________________________________________________________________________ 
wt. 
A-Fax 500 0.863 
305 500- 0.3- 1.03- 
ca 500 & -- -- 
10,000 0.7 1.07 
ca 18,000 
A-Fax 600 0.863 
205- 50- 0.17 1.017 
500 -- -- 
220 100 
A-Fax 700 0.84 305 310,000 0.84 -- 2940 & 2,470 164,000 
(propylene- 152,000 
ethylene copolymer 
resin) 
A-Fax 800 0.84 -- 50 0.15 -- 5540 & 2,010 10,300 
190 
A-Fax 900A 
0.86 310 1,650 0.39 -- 5870 3,460 43,200 
A-Fax 900B 
0.86 310 3,565 0.42 -- -- -- -- 
A-Fax 900D 
0.86 310 5,450 0.51 -- -- -- -- 
__________________________________________________________________________ 
Because of the lack of crystallinity, the softening points as measured by 
ring and ball are much lower than expected for crystalline isotactic 
polypropylene. Crystalline isotactic polypropylene has a melting point in 
the range of about 165.degree.-189.degree. C. Commercially available 
isotactic polypropylene generally shows a melting transition by 
differential thermal analysis (DTA) somewhat lower, usually in the range 
of about 155.degree.-165.degree. C. 
The non-elastomeric, amorphous copolymer of propylene and ethylene or the 
like suitable for use in this invention differs from the rubbery 
copolymers of alpha-olefins, typically propylene and ethylene, in the very 
low viscosity. Whereas the EPM and EPDM have high viscosity, typically 
measured on a Mooney viscometer, the amorphous non-elastomeric copolymers 
employed as Component B herein have viscosity ranges too low to be 
measured by a Mooney viscometer as a practical matter. Ordinarily the 
viscosity of amorphous non-rubbery ethylene-propylene copolymer at 
375.degree. F. in a Brookfield Thermosel will be less than 500,000 cps, 
and typically is in the range 300,000-350,000 cps. A typical copolymer 
rubber EPM or EPDM in contrast would have a Brookfield viscosity at 
375.degree. F., one or more order of magnitude higher than 500,000. 
Typical conventional amorphous polypropylene is a solid low molecular 
weight polymer of propylene (number average molecular weight of 500-35,000 
preferably 1,000-10,000), soluble in lower hydrocarbons such as pentane or 
xylene, and usually having less than 5% by weight crystalline component. 
For the purposes of this invention, amorphous polypropylene made by any of 
the known processes may be used. Preferably, it is the propylene soluble 
constituent of the total polymer prepared from propylene monomer using a 
catalyst comprising a titanium halide and alkyl aluminum as disclosed in 
Scoggin, U.S. Pat. No. 3,280,090 and Moon, U.S. Pat. No. 3,257,372, the 
disclosures of which are hereby incorporated by reference. It can be made 
also using a metal oxide type catalyst such as chromic oxide on alumina. 
An examplary conventional amorphous polypropylene is the hot methanol 
extraction product of a waste stream of impure amorphous polypropylene 
recovered from a propylene polymerization process employing a titanium 
halide/alkyl aluminum catalyst. The methanol extraction is described in 
U.S. Pat. No. 3,661,884, the disclosure of which is hereby incorporated by 
reference. Properties are as follows: 
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Weight Average - Molecular Wt. 
about 4,000 
Ring & Ball Softening Point 
187.degree. F. 
Melt Viscosity at 200.degree. F. 
890 
Melt Viscosity at 275.degree. F. 
125 
Melt Viscosity at 375.degree. F. 
35 
______________________________________ 
A remarkable feature of the present invention is the effect of amorphous 
polypropylene or amorphous ethylene-alpha-olefin non-elastomeric copolymer 
on the blend of crystalline alpha-olefin resin with alpha-olefin copolymer 
rubber. The chemical structure of the repeating units of amorphous 
polypropylene is identical with the repeating units of crystalline 
polypropylene, the difference being the tacticity. The chemical structure 
is not identical with that of the alpha-olefin copolymer rubber, which 
unlike the amorphous polypropylene contains two or more alpha-olefin 
repeating units. It is thus surprising that the physical characteristics 
of the blend indicate that all the amorphous polypropylene blends only 
with the alpha-olefin rubber phase of the blend, and none with the 
crystalline alpha-olefin resin. Thus, modulus and tensile of the blend, 
measured at room temperature depend only upon the percentage composition 
of crystalline alpha-olefin, and does not depend upon the relative 
percentage composition of alpha-olefin and amorphous polypropylene. If 
amorphous polypropylene, being much softer than crystalline polypropylene, 
had mixed with crystalline polypropylene the hardness of the blend would 
be expected to decrease. The hardness, measured in Shore A or Shore D 
units is not, however, decreased. 
The remarkable utility of the blends of the invention will be manifest from 
the physical properties of representative blends as illustrated by the 
examples below. Replacing a portion of the alpha-olefin copolymer rubber A 
by amorphous polypropylene B in effect extends the rubber, while 
substantially maintaining good tensile strength and modulus, with 
generally no adverse effect upon hardness, and with generally increased 
elongation. In the conventional thermoplastic elastomeric blends based on 
monolefin copolymer rubber A and crystalline polyolefin resin C, the use 
of other extenders such as hydrocarbon oil as a partical replacement of 
the alpha-olefin copolymer rubber unfortunately decreases the hardness and 
leads to tensiles substantially lower than the mixes without such 
extenders. In contrast, such hydrocarbon oils can be used advantageously 
in blends of this invention. It is a remarkable feature of the present 
invention that incorporation of oil into a blend in which a portion of 
alpha-olefin copolymer rubber A has been replaced by amorphous 
polypropylene B does not lead to a decrease in hardness nor loss of 
tensile strength of the magnitude such oil produces in a comparable blend 
containing only alpha-olefin copolymer rubber in addition to crystalline 
polypropylene. 
Blends of this invention containing amorphous polypropylene are generally 
somewhat harder than comparable blends containing alpha-olefin copolymer 
rubber with levels of crystalline polypropylene and oil equivalent to the 
blend containing a portion of amorphous polypropylene in place of an 
equivalent portion of alpha-olefin copolymer rubber. By adjusting 
proportionate amounts of amorphous polypropylene, alpha-olefin copolymer 
rubber, and oil with a fixed amount of crystalline polypropylene, blends 
can be prepared which are equivalent in hardness to a blend containing the 
fixed amount of crystalline polypropylene, alpha-olefin copolymer rubber, 
and oil, but said blend can be made to contain a much higher proportion of 
oil plus amorphous polypropylene. 
Greatly improved flow characteristics are exhibited by the composition of 
the present invention over comparable blends not containing amorphous 
polypropylene. This improved flow is characterized by greatly decreased 
capillary viscosity measured by a McKelvey rheometer at suitable 
temperature. The decreased viscosity makes fabrication of injection-molded 
objects much faster and easier, both by improving flow into a mold, and by 
decreasing the pressure needed to fill the mold with the thermoplastic 
elastomer. 
Usually the following procedure is applied in carrying out the invention: 
(1) The monoolefin copolymer elastomer, the polyalpha-olefin plastic, the 
amorphous polypropylene or amorphous propylene alpha-olefin compolymer, 
and if so desired, the curing agent and/or filler, are charged at the 
desired ratio to a suitable mixer such as Banbury internal mixer, 
transfer-type extruder-mixer, extruder, or any such device that will 
enable efficient mastication at the desired temperature. Such blending 
apparatus may be preheated to reduce the time required to reach a 
processing temperature range, provided that such preheating temperature is 
below the decomposition temperature of the curing agent used. 
(2) While mixing, the temperature is increased to above the decomposition 
temperature of the curing agent, if used, and usually the mix is held at 
such a temperature, while continuing the mixing, for a time period long 
enough to ensure at least 95% decomposition of the curing agent, based on 
its theoretical half life at said temperature, and thorough mixing of the 
blend. If no curing agent is used, the mix is simply worked at a 
temperature sufficiently elevated to soften the ingredients and mix them 
intimately. 
(3) After having processed the blend to a degree described under (2), an 
antioxidant is ordinarily added to the blend and processing is continued 
usually for one minute or more in order to thoroughly incorporate the 
antioxidant in the blend for the purpose of deactivating any residual 
curing agent and enhancing protection against oxidative degradation of the 
composition. 
(4) If so desired the resultant product may be refined on a mill before 
being used to form shaped articles by means of extrusion, injection 
molding, press molding or any suitable means of manufacture. 
If a dynamic semi-curing step is carried out, suitable curing agents and 
curing conditions are as described in Fischer U.S. Pat. No. 3,806,558 
(including col. 3, line 21 to col 4, line 24 and col 5, line 25 to col 6, 
line 51), the disclosure of which is hereby incorporated herein by 
reference. Briefly, such curatives include any conventional curing or 
vulcanizing agents effective in the monoolefin copolymer rubber A, 
especially peroxides, with or without sulfur or other co-curing agents or 
activators. It will be understood that the thus dynamically semi-cured 
blend remains a thermoplastic materal that can be reprocessed repeatedly, 
but it has elastomeric properties without requiring further cure. Without 
desiring to be limited to any particular theory of operation, it appears 
that the shearing imparted during the dynamic cure (cure while masticating 
or working) may break down a certain amount of the cross-linkages, so that 
the material remains thermoplastic in spite of the curing reaction. For 
this purpose any conventional curative or radiation may generally be 
employed. Examples of conventional curatives include such free-radical 
generating agents or cross-linking agents as the peroxides, whether 
aromatic or aliphatic as in the aromatic diacyl peroxides and aliphatic 
diacyl peroxides, dibasic acid peroxides, ketone peroxides, alkyl 
peroxyesters, alkyl hydroperoxides, e.g., diacetylperoxide, 
dibenzoylperoxide, bis-2,4-dichlorobenzoylperoxide, di-tert-butylperoxide, 
dicumylperoxide, tert-butylperbenzoate, tert-butylcumylperoxide, 
2,5-bis(tert-butylperoxy)2,5-dimethylhexane, 
2,5-bis-(tert-butylperoxy)-2,5-dimethylhexyne-3; 
4,4,4',4'-tetra-(tert-butylperoxy)-2,2-dicyclohexylpropane, 
1,4-bis-(tert-butylperoxyisopropyl)-benzene, 1,1-bis-(tert-butylperoxy) 
3,3,5-trimethylcyclohexane, lauroyl peroxide, succinic acid peroxide, 
cyclohexanone peroxide, tert-butyl peracetate, butyl hydroperoxide, etc. 
Also suitable are the azide types of curing agents including such 
materials as the azidoformates (e.g., tetramethylenebis (azidofomrate); 
for others see U.S. Pat. No. 3,284,421, Breslow, Nov. 8, 1966), aromatic 
polyazides (e.g., 4,4'-diphenylmethan diazide; for others see U.S. Pat. 
No. 3,297,674, Breslow et al., Jan. 10, 1967), and sulfonazides such as 
p,p'-oxybis(benzene sulfonyl azide), etc. Other curatives that may be used 
include the aldehydeamine reaction products such as formaldehyde-ammonia 
formaldehyde-ethylchloride-ammonia, acetaldehyde-ammonia, 
formaldehyde-aniline, butyraldehyde-aniline, heptaldehydeaniline, 
heptaldehyde-formaldehyde-aniline, hexamethylenetetramine, 
alpha-ethyl-beta-propyl-acrolein-aniline; the substituted ureas (e.g., 
trimethylthiourea, diethylthiourea, dibutylthiourea, tripentylthiourea, 
1,3-bis (2-benzothiazolylmercaptomethyl) urea, and N,N-diphenylthiourea); 
guanidines (e.g., diphenylguanidine, di-o-tolylguanidine, 
diphenylguanidine phthalate, and di-o-tolylguanidine salt of dicatechol 
borate); xanthates (e.g. zinc ethylxanthate, sodium isopropylxanthate, 
butylxanthic disulfide, potassium isopropylxanthate, and zinc 
butylxanthate; dithiocarbamates (e.g., copper dimethyl-, zinc dimethyl-, 
tollurium diethyl-, cadmium dicyclohexyl-, lead dimethyl-, selenium 
dibutyl-, zinc pentamethylene-, zinc didecyl-, and zinc isopropyloctyl-, 
dithiocarbamate); thiazoles (e.g., 2-mercaptobenzothiazole; zinc 
mercaptothiazolyl mercaptide, 2-benzothiazolyl-N,N-diethylthiocarbamyl 
sulfide, and 2,2'-dithiobis(benzothiazole); imidazoles (e.g., 
2-mercaptoimidazoline and 2-mercapto-4,4,6-trimethyldihydropyrimidine); 
sulfenamides (e.g., N-t-butyl-2-benzothiazole-, 
N-cyclohexylbenzothiazole-, N,N-di-isopropylbenzothiazole-, 
N-(2,6-dimethylmorpholino)-2-benzothiazole-, and 
N,N-diethylbenzothiazole-sulfenamide); thiuramdisulfides (e.g., 
N,N'-diethyl-, tetrabutyl-, N,N'-di-isopropyldioethyl-, tetramethyl-, 
N,N'-dicyclohexyl-, and N,N'-tetralaurylthiuramdisulfide); also 
paraquinone-dioxime, dibenzoparaquinonedioxime, etc. as well as sulfur 
itself (see Encyclopedia of Chemical Technology, Vol. 17, 2nd edition, 
Interscience Publishers, 1968; also Organic Peroxides, Daniel Severn, Vol. 
1, Wiley-Interscience, 1970). The peroxide curative may be used alone, or 
in conjunction with the usual auxiliary substances such as sulfur, 
maleimides including bis-maleimides, poly-unsaturated compounds (e.g., 
cyanurate), acrylic esters (e.g., trimethylolpropanetrimethacrylate), etc. 
With sulfur curatives, such as sulfur itself or sulfur donors, it is 
usually desirable to include an accelerator of sulfur vulcanization as 
well as an activator (e.g., a metal salt or oxide), as in conventional 
practice. Mixed peroxide-type or mixed sulfur-type curing systems may be 
employed if desired such as dicumylperoxide plus 
2,5-bis(tert-butylperoxy)-2,5-dimethylhexane or sulfur plus 
tetramethylthiuramdisulfide. The preferred monnolefin copolymers having 
residual unsaturation, conferred by the presence of a polyene, such as 
EPDM, afford the widest choice of curatives. Reference may be had to 
"Vulcanization and Vulcanizing Agents," W. Hoffman, Palmerton Publishing 
Co., New York, 1967, for an extensive disclosure of curing agents. The 
time and temperature required for cure are in accordance with known 
practice, and will depend mainly in the particular curative selected as 
well as other details of the formulation, as is well understood by those 
skilled in the art. The curative is believed to affect mainly the 
monoolefin copolymer rubber component A, but, depending on the particular 
curative, there may be some cross-linking effect on the resinous 
components B and/or C as well. In any case the treatment may be regarded 
as a semi-cure or partial cure, to the extent that the product remains 
processable and thermoplastic, probably because of breaking down of 
crosslinks by the masticating action while the dynamic cure is in 
progress. Thus, the blend does not become crosslinked to the extent that 
it will no longer knit together into a coherent mass in conventional 
rubber or plastic processing machinery. 
Any conventional extender oil may be employed in the composition of the 
invention. Non-limiting examples are extender and process oils, whether 
derived from petroleum, obtained from other natural sources or 
manufactured synthtically, examples of extender and process oils being 
paraffinic oils and naphthenic oils. Further description of conventional 
extender oils in softeners will be found in Whitby, "Synthetic Rubber," 
Wiley & Sons, New York, 1954, page 383 wherein they are classified into 
solvents (aromatic hydrocarbons, chlorinated hydrocarbons, aliphatic 
hydrocarbons, and terpenes and related compounds such as gum turpentine 
and resin), partial solvents (esters, high-molecular weight ketones, and 
naphthalenes), and non-solvents (alcohols, phenols, low-molecular weight 
ketones, branched-chain aliphatic hydrocarbons, amines, and other 
alcohols). Important extender oils include the paraffinic, naphthenic and 
aromatic type substantially non-volatile compatible mineral oils described 
in U.S. Pat. No. 3,438,920, Halper et al, Apr. 15, 1969, especially col. 
2, lines 38-48 and the table at cols. 3 and 4, lines 7-40, the disclosure 
of which is hereby incorporated herein by reference; see also U.S. Pat. 
No. 2,964,083, Pfau et al, Dec. 13, 1960. 
The composition may further include other conventional compounding 
ingredients such as particulate or fibrous fillers (non-limiting examples 
are calcium carbonate, carbon black, silica, glass, asbestos, clay, talc), 
pigments, processing aids or lubricants, mold release agents, u.v. 
screening agents, antioxidants or stabilizers for the rubber or resin or 
both, etc. Any conventional antioxidant or stabilizer may be used, 
including, by way of non-limiting example, amine types, phenolic types, 
sulfides, phenyl alkanes, phosphites, etc. Representative materials are 
listed in "Rubber: Natural and Synthetic," Stern, Palmerton Publishing 
Co., New York, 1967, especially at pages 244-256; see also "Chemistry and 
Technology of Rubber," Davis & Blake, Reinhold, New York, 1937, Chapter 
XII. Included are such materials as 2,2,4-trimethyl-1,2-dihydroquinoline, 
diphenylamine acetone condensate, aldol-alpha-naphthylamine, octylated 
diphenylamine, N-phenyl-N'-cyclohexyl-p-phenylenediamine, 
2,6-di-tert-butyl-4-methylphenol, styrene-resorcinol resin, 
o-cresol-monosulfide, di-p-cresol-2-propane, 
2,5-di-tert-amyl-hydroquinone, dilauryl-3,3'-thiodipropionate and similar 
dialkyl thiodipropionates, etc. 
The form of the invention involving a dynamic semi-curing step is 
particularly advantageous from the standpoint of providing better melt 
flow, improved high temperature physicals and better die swell. A 
preferred elastomer for use in the invention is the low unsaturation type 
of EPDM terpolymer, containing such non-conjugated dienes as 
1,4-hexadiene, dicyclopentadiene or 5-ethylidene-2-norbornene. Preferred 
curatives for these are the peroxide, sulfur or azide types described 
above. 
The following examples, in which all quantities are expressed by weight 
unless otherwise indicated, will serve to illustrate the practice of the 
invention in more detail. 
EXAMPLE 1 
This example illustrates uncured thermoplastic elastomers of the invention. 
Table I shows a series of blends, identified by the letters A through AAA, 
containing the ingredients shown in the table, expressed in parts by 
weight mixed following the general procedure described above. The 
ingredients are identified as follows: 
EPDM is an unsaturated sulfur-vulcanizable elastomeric terpolymer of 
ethylene, propylene and dicyclopentadiene, in which the ethylene: 
propylene weight ratio is 53: 47; iodine number 10; Mooney viscosity 90 
(ML-4 at 212.degree. F.). 
EPM is a saturated elastomeric copolymer of ethylene and propylene; 
ethylene: propylene weight ratio 45: 55; Mooney viscosity 66 (ML-4 at 
212.degree. F.). 
Cryst PP 1 is a largely crystalline isotactic polypropylene resin 
commercially available as Profax (trademark) 6253 having a melt flow index 
of 4 at 230.degree. C. (ASTM D 123-587) and a density of 0.903 g/cc. 
Cryst PP 2 is a largely crystalline isotactic polypropylene resin, Profax 
6323, having a melt flow index of 11 at 230.degree. C. and a density of 
0.903 g/cc. 
Amor PP 1 is an essentially amorphous polypropylene commercially available 
as A-Fax (trademark) 500, described in Table A above. 
Amor PP2 is an essentially amorphous polypropylene A-Fax 600, described in 
Table A above. 
Amor P(PE) Co is an essentially amorphous propylene-ethylene copolymer 
A-Fax 700 containing from 15 to 25% by weight of ethylene described in 
Table A above. 
Amor PP3 is an essentially amorphous polypropylene, A-Fax 800, described in 
Table A above. 
Amor PP4 is an essentially amorphous polypropylene, A-Fax 900-A, described 
in Table A above. 
Amor PP5 is an essentially amorphous polypropylene, A-Fax 900-D, described 
in Table A above. 
The filler is magnesium silicate maximum particle size 6 microns, 
commercially available as Mistron Vapor (trademark). 
Oil 1, a petroleum hydrocarbon extender oil, is a mixed paraffinic and 
naphthenic processing oil, Tufflo (trademark) 6056, liquid viscosity 
(100.degree. F.) 505 SUS; specific gravity (60.degree. F.) 0.8762; flash 
point 450.degree. F., molecular weight 550. 
Oil 2 is a petroleum hydrocarbon extender oil, Sun Par 150, a paraffinic 
oil containing 16.3% aromatic; liquid viscosity (100.degree. F.) 515 SUS; 
specific gravity (60.degree. F.) 0.880; molecular weight 505. 
Mixes A through QQ further contain 1.5 parts of conventional antioxidant as 
described above (e.g., diphenylamine acetone condensate); the remaining 
mixes RR through AAA contain 1.25 parts of the antioxidant. 
A Banbury mixer is charged at 0-80 psi steam, with the EPDM or EPM, 
crystalline polypropylene, amorphous polypropylene, filler if used and 
antioxidants. 
If used, the oil, a portion or all, is usually added last. Two or more of 
the components may be pre-mixed as a masterbatch before adding to the 
Banbury. Temperature is raised sufficiently to melt the crystalline 
polypropylene, usually to a temperature of 350.degree. F. or above, mixed 
for at least one minute at the elevated temperature, and dropped. The hot 
mix is usually sheeted out to convenient thickness on a mill, heated to 
about 240.degree.-320.degree. F. 
The mill sheet is granulated to convenient size for injection molding. Test 
specimens are typically prepared in screw injection molding machine. 
TABLE I 
__________________________________________________________________________ 
A B C D E F G H I J K L M N O P Q R 
__________________________________________________________________________ 
EPDM 35 30 25 25 30 25 50 40 45 40 40 40 60 50 40 
EPM 50 50 60 
Cryst. PP1 
65 65 65 65 65 65 50 50 50 50 50 50 40 40 40 40 40 40 
Cryst. PP2 
Amor. PP1 5 10 10 10 10 10 10 10 20 
Amor. PP2 5 10 10 10 10 
Amor. P(PE)Co 
Amor. PP3 
Amor. PP4 
Amor. PP5 
Filler 10 10 10 
Oil 1 10 
Oil 2 
Antioxidant 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
Hardness, 
Shore A 91 94 93 91 
Hardness, 
Shore D 52 50 52 52 52 53 44 45 45 51 50 45 33 34 
ROOM 
TEMPERATURE 
100% Modulus, 
2276 
2176 
2275 
2442 
2472 
2488 
1867 
1885 
1890 
1914 
1896 
1889 
1337 
1331 
1469 
1523 
1568 
1338 
psig. 
300% Modulus, 
2138 
2181 
2260 
2267 
2274 
2271 
1737 
1798 
1780 
-- -- 1777 
1315 
-- -- -- 1439 
-- 
psig. 
Tensile, psig. 
2318 
2299 
2392 
2415 
2425 
2462 
1829 
1863 
1863 
1870 
1862 
1893 
1401 
1347 
1480 
1537 
1565 
1373 
Ultimate 310 
260 
267 
213 
345 
350 
250 
252 
230 
192 
212 
240 
297 
282 
155 
160 
265 
210 
Elongation, % 
Permanent Set, % 150 
182 
145 
120 
127 
192 
185 
157 
60 67 159 
104 
250.degree. F. 
100% Modulus, 
744 
472 
614 
644 
705 
518 
474 
438 
422 
469 
491 
519 
308 
283 
384 
392 
350 
333 
psig. 
300% Modulus, 
796 
501 
633 
654 
699 
556 
518 
449 
428 
455 
465 
500 
-- -- 348 
305 
378 
321 
psig. 
Tensile, psig. 
1011 
862 
1058 
996 
1026 
996 
648 
631 
581 
624 
602 
649 
337 
306 
519 
510 
498 
484 
Ultimate 1007 
1366 
1380 
1407 
1250 
1563 
893 
1283 
1440 
1393 
903 
1133 
1022 
1000 
637 
667 
880 
760 
Elongation, % 
Compression Set, 
22 Hrs. R.T. 
__________________________________________________________________________ 
S T U V W X Y Z AA BB CC DD EE FF GG HH II JJ 
__________________________________________________________________________ 
EPDM 50 40 30 70 60 45 60 45 50 40 40 00 40 
EPM 50 40 50 40 30 
Cryst. PP1 
40 40 40 40 40 40 40 40 30 30 30 30 30 50 50 50 50 50 
Cryst. PP2 
Amor. PP1 
10 20 10 25 10 
Amor. PP2 10 20 30 10 20 30 10 25 10 
Amor. P(PE)Co 10 
Amor. PP3 
Amor. PP4 10 
Amor. PP5 
Filler 
Oil 1 
Oil 2 
Antioxidant 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
Hardness, 
Shore A 90 91 94 92 92 93 92 -- 84 89 88 87 88 95 95 95 96 96 
Hardness, 
Shore D 
ROOM 
TEMPERATURE 
100% Modulus, 
1455 
1418 
1565 
1513 
1427 
1407 
1366 
1331 
1080 
1152 
1107 
1119 
1090 
2057 
1991 
1956 
1998 
2094 
psig. 
300% Modulus, 
-- 1435 
1443 
1394 
1389 
1336 
1395 
1339 
-- 1077 
1044 
-- 1039 
-- -- -- -- -- 
psig. 
Tensile, psig. 
1468 
1456 
1570 
1511 
1442 
1461 
1408 
1387 
1107 
1176 
1132 
1150 
1111 
1939 
1961 
1919 
1956 
2043 
Ultimate 222 
327 
252 
275 
340 
297 
320 
395 
147 
227 
282 
210 
245 
197 
177 
210 
197 
170 
Elongation, % 
Permanent Set, % 
120 
219 
149 
172 
222 
192 
205 
275 
50 95 146 
-- 122 
95 92 120 
120 
92 
250.degree. F. 
100% Modulus, 
386 
317 
371 
328 
287 
350 
291 
297 
267 
288 
208 
243 
204 
509 
453 
462 
486 
445 
psig. 
300% Modulus, 
480 
339 
403 
346 
313 
393 
317 
314 
253 
266 
232 
219 
232 
471 
435 
484 
446 
462 
psig. 
Tensile, psig. 
493 
477 
510 
478 
411 
553 
448 
506 
289 
332 
305 
305 
293 
491 
498 
527 
520 
654 
Ultimate 880 
1072 
740 
910 
1030 
952 
1100 
1155 
295 
462 
785 
522 
747 
837 
952 
742 
1057 
1057 
Elongation, % 
Compression Set, 79.5 
80.9 
68.9 
79.3 
75.8 
22 Hrs. R.T. 
__________________________________________________________________________ 
KK LL MM NN OO PP QQ RR SS TT UU VV WW XX YY ZZ AAA 
__________________________________________________________________________ 
EPDM 40 40 40 40 40 40 40 45 40 35 30 40 49 52.5 
41 60 37.5 
EPM 
Cryst. PP1 
50 50 50 50 50 50 50 40 40 40 40 -- 35 30 45 -- 50 
Cryst. PP2 40 40 
Amor. PP1 10 15 20 25 30 20 16 17.5 
14 12.5 
Amor. PP2 10 
Amor. P(PE)Co 10 
Amor. PP3 10 10 
Amor. PP4 10 
Amor. PP5 
10 
Filler 
Oil 1 
Oil 2 10 10 10 10 10 
Antioxidant 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1.25 
1.25 
1.25 
1.25 
1.25 
1.25 
1.25 
1.25 
1.25 
1.25 
Hardness, 
Shore A 96 96 96 95 94 96 96 95 95 96 96 94 95 93 94 94 96 
Hardness, 
Shore D 33 36 37 38 40 38 35 44 36 48 
ROOM 
TEMPERATURE 
100% Modulus, 
1996 
1965 
1784 
1756 
1681 
1675 
1789 
1447 
1419 
1379 
1355 
1284 
1190 
1013 
1611 
1309 
1808 
psig. 
300% Modulus, 
-- -- -- 1756 
-- 1562 
1600 
1353 
1321 
1259 
1302 
1194 
1189 
1033 
1486 
1269 
1638 
psig. 
Tensile, psig. 
2048 
1941 
1786 
1797 
1640 
1698 
1800 
1458 
1432 
1382 
1371 
1270 
1233 
1077 
1611 
1337 
1824 
Ultimate 182 
197 
270 
270 
277 
290 
245 
279 
320 
305 
228 
228 
291 
300 
310 
220 
293 
Elongation, % 
Permanent Set, % 
90 115 
160 
150 
175 
140 
140 
170 
165 
150 
155 
150 
140 
130 
175 
100 
230 
250.degree. F. 
100% Modulus, 
450 
456 
366 
274 
338 
401 
351 
psig. 
300% Modulus, 
483 
473 
400 
300 
364 
415 
366 
psig. 
Tensile, psig. 
560 
529 
501 
480 
454 
479 
393 
Ultimate 1035 
880 
1015 
932 
920 
857 
1200 
Elongation, % 
Compression Set, 
75.5 
78.6 
82.1 
83.2 
83.8 
83.5 
79.2 
22 Hrs. R.T. 
__________________________________________________________________________ 
EXAMPLE 2 
In this example, two cured Base Polymer mixtures are first prepared 
identified as Base Polymer I and II in Table II, both of which contain 
EPDM and crystalline polypropylene (Cryst PP 1) as identified in Example 
1; one of these Base Polymers contains amorphous polypropylene (Amor PP 1 
of Example 1), while the other does not. The curing agent is 
2,5-bis(tertiarybutylperoxy)-2,5-dimethylhexane (Varox; trademark). 
Table II shows the amounts of each ingredient, in parts by weight. 
The procedure involves preparing cured blends A and B in a Banbury by 
charging first the EPDM, crystalline polypropylene, and amorphous 
polypropylene if used. The curing agent is added, and the temperature is 
raised to 350.degree. F. or higher. After 2 minutes at 350.degree. F. or 
higher the antioxidant is added and mixed, to destroy residual traces of 
curing agent. The mix is dropped and sheeted on a mill. The sheeted mix is 
cut into convenient size pieces. These weighed pieces are loaded into a 
Banbury, along with the other ingredients, of blends C, D, E, F, G, H. The 
temperature of the Banbury is raised to 350.degree. F. or higher allowing 
at least two minutes of mixing at elevated temperature. The charge is 
dropped, sheeted on a mill and granulated. Test pieces are prepared in a 
screw injection molding machine. 
Base Polymer I is outside the invention; Base Polymer II is within the 
invention. 
Table III shows the physical properties of injection molded specimens of 
each of the two Base Polymers, as well as a series of mixes made by adding 
additional ingredients in the amounts shown in Table III, wherein Cryst PP 
1 is again the crystalline polypropylene used in Example 1, Amor PP 1 is 
again the amorphous polypropylene used in Example 1, and Oil 1 is extender 
oil as identified in Example 1. 
Final blend A, C and E are outside the invention. It will be observed from 
the Table III data that good tensile strength is maintained while 
elongation and flow properties are improved. 
TABLE II 
______________________________________ 
Cured Base Polymers 
I II 
______________________________________ 
EPDM 80 60 
Crystalline -PP1 
20 20 
Amorphous 
PP1 -- 20 
Curing Agent 0.8 0.8 
Antioxidant 1.5 1.5 
______________________________________ 
TABLE III 
__________________________________________________________________________ 
A B C D E F G H 
__________________________________________________________________________ 
Base Polymer I 
100 75 100 
100 
Base Polymer II 100 75 100 
100 
Cryst. PP1 25 25 
Amor. PP1 10 10 
Oil 1 20 20 20 20 
Hardness, Shore A 
72 80 94 95 64 68 68 72 
Hardness, Shore D 
25 30 36 40 11 14 11 15 
ROOM TEMPERATURE 
100% Modulus, psig. 
408 
429 
1440 
1269 
315 
373 
279 
302 
300% Modulus, psig. 
-- 598 
1477 
1368 
476 
467 
394 
375 
Tensile, psig. 
609 
606 
1478 
1403 
460 
479 
424 
408 
Ultimate Elongation, % 
225 
315 
282 350 254 
308 
330 
358 
Set, % 30 55 115 150 26 35 54 59 
250.degree. F. 
100% Modulus, psig. 
124 
102 
333 283 -- -- -- -- 
300% Modulus, psig. 
-- 147 
420 343 -- -- -- -- 
Tensile, psig. 
165 
147 480 
523 -- -- -- -- 
Ultimate Elongation, % 
167 
300 
473 840 -- -- -- -- 
COMPRESSION SET 
22 Hrs. Rm. Temp. % 
45.6 
56.9 
-- -- 
70 Hrs. Rm. Temp. % 40.8 
49.0 
54.8 
55.7 
Capillary Flow 
9.5 
4.5 
-- -- 5.8 
4.2 
2.9 
1.7 
poises X 10.sup.3 
(410 Sec.sup.-1 & 350.degree. F.) 
Flexural Modulus, psig. 
-- -- 31,800 
34,800 
__________________________________________________________________________ 
EXAMPLE 3 
Five masterbatches, identified as Masterbatches I to V in Table IV, are 
prepared from the ingredients indicated in Table IV, using Varox peroxide 
curing agent, according to the procedure of Example 2. 
Masterbatches II, III, IV, and V are within the invention; Masterbatch I is 
outside the invention. 
These masterbatches are used to prepare test specimens A to J in Table V, 
according to the procedure of Example 2. Specimens A and F are outside the 
invention. Tensile strengths, which are somewhat low in cured samples 
compared to uncured, can be improved by addition of crystalline 
polypropylene after the curing step. 
TABLE IV 
______________________________________ 
MASTERBATCH.fwdarw. 
I II III IV V 
______________________________________ 
EPDM 1 80 0 60 50 50 
Cryst. PP1 20 20 20 20 20 
Amor. PP1 20 30 
Amor. PP2 20 30 
Curing Agent 0.8 0.8 0.8 0.8 0.8 
Antioxidant 1.0 1.0 1.0 1.0 1.0 
______________________________________ 
TABLE V 
__________________________________________________________________________ 
RUNS.fwdarw. A B C D E F G H I J 
__________________________________________________________________________ 
Masterbatch I 100 75 
Masterbatch II 100 75 
Masterbatch III 100 75 
Masterbatch IV 100 75 
Masterbatch V 100 75 
Cryst. PP1 25 25 25 25 25 
Hardness, Shore A 
78 82 82 86 84 94 94 94 95 94 
ROOM TEMPERATURE 
100% Modulus, psig. 
539 
507 
455 
438 
381 
1312 
1275 
1230 
1206 1233 
300% Modulus, psig. 
-- 681 
595 
510 
447 
1409 
1313 
1248 
1245 1240 
Tensile, psig. 
700 
695 
620 
529 
469 
1483 
1468 
1377 
1291 1335 
Ultimate Elongation, % 
235 
342 
355 
327 
372 
265 
352 
322 357 385 
Permanent Set, % 
29 70 65 72 90 107 
177 
166 196 213 
250.degree. 
100% Modulus, psig. 
151 
111 
97 71 61 334 
310 
342 213 316 
300% Modulus, psig. 
-- 144 
139 
77 70 395 
355 
367 212 340 
NO 
Tensile, psig. 
190 
152 
139 
82 76 448 
468 
478 BREAK 
516 
Ultimate Elongation, % 
197 
317 
350 
455 
500 
540 
750 
805 &gt;1600 
1010 
Compression Set, % 
63.7 
71.4 
73.6 
78.2 
77.3 
75.7 
80.7 
71.4 
84.2 77.1 
22 Hrs. @ 150.degree. F. 
__________________________________________________________________________ 
EXAMPLE 4 
In a first stage, mixtures of EPDM rubber and crystalline polypropylene, 
with or without amorphous polypropylene, in the proportions indicated in 
Table VI are worked in a Banbury mixer with Varox peroxide curative at 
350.degree. F. for 2 minutes to effect a dynamic cure. Antioxidant is 
added. 
Thereafter, in a second stage, an additional charge of one or more of the 
following are added and mixed at 350.degree. F. for 2 minutes, in the 
proportions indicated in Table VI: 
(1) crystalline polypropylene 
(2) amorphous polypropylene 
(3) oil. 
Blends A and C are outside the limits of the invention. 
This example demonstrates a modification of the mixing procedure of 
examples 2 and 3, in which masterbatches are first prepared, then remixed 
with additional ingredients added in a second mixing stage. In the present 
example, a masterbatch is prepared as before, and a second charge is 
loaded in on top of the first charge, after curing, and after addition of 
antioxidant. The second charge is mixed well before the charge is dropped, 
then processed as in the preceding examples 2 and 3. 
The present example also demonstrates that relatively large quantities of 
combined amorphous polypropylene and oil can be incorporated into mixes, 
while maintaining satisfactory physical properties. 
TABLE VI 
__________________________________________________________________________ 
FIRST STAGE 
RUN NUMBER.fwdarw. 
A B C D E F G H 
__________________________________________________________________________ 
EPDM 60 40 80 60 80 60 70 60 
Crystalline PP1 
25 25 20 20 20 20 20 20 
Amorphous PP1 20 20 20 10 15 
Curing Agent 0.8 
0.8 
0.8 
0.8 
0.8 
0.8 
0.8 
0.8 
Antioxidant 1.25 
1.25 
1.25 
1.25 
1.25 
1.25 
1.25 
1.25 
__________________________________________________________________________ 
SECOND STAGE 
Crystalline PP1 
15 15 
Amorphous PP1 20 20 20 20 
Oil 1 20 20 10 10 10 20 
Hardness, Shore A 
93 95 67 74 72 78 76 72 
Hardness, Shore D 
34 36 14 16 16 18 18 15 
ROOM TEMPERATURE 
100% Modulus, psig. 
964 
1041 
257 
292 
314 
293 
313 
246 
300% Modulus, psig. 
1202 
1160 
349 
372 
428 
332 
389 
306 
Tensile, psig. 
1336 
1193 
340 
391 
417 
343 
398 
312 
Ultimate Elongation, % 
388 
443 
245 
328 
318 
348 
340 
338 
Permanent Set, % 
149 
220 
25 55 40 75 55 55 
__________________________________________________________________________