Heat-sealable vulcanizates comprising polyolefin rubber and propylene polymer

Polyolefin rubber compositions which are readily heat-sealable are provided by the addition of 5-100 parts by weight, based on the polyolefin elastomer, of a propylene polymer uniformly admixed therewith prior to vulcanization which is selected from the group consisting of polypropylene and copolymers of propylene with up to 20% by weight of ethylene, butene-1 or hexene-1 which polymer has a heptane-extractable portion of 5-60%, and I-value measured according to DIN 53 728 of 100-600 cm.sup.3 /g. and a yield point measured according to DIN 53 735 of 10-30 N/mm.sup.2.

BACKGROUND OF THE INVENTION 
This invention relates to heat-sealable polyolefin elastomer vulcanizates. 
Articles of vulcanized polyolefin elastomers are primarily utilized, as is 
known, in applications where high requirements must be met with respect to 
resistance against the effects of weathering and aging. Thus, a desirable 
application in the building industry is, for example, the utilization of 
sheets of ethylene-propylene copolymers (EPM), ethylenepropylene-diene 
terpolymers (EPDM) or butyl rubber (BR) as roof covering. In this type of 
roofing, tightness is largely determined and limited by the rather 
problematical way of laying the sheets to form seams or overlapping 
portions. For this reason, several attempts have already been made to join 
articles of vulcanized polyolefin elastomers with each other or with 
articles of other materials. 
Thus, it has been known from DAS (German Published Application) No. 
1,620,832 to conduct a process for the manufacture of a solid adhesive 
bond between polyethylene and natural or synthetic rubber by vulcanization 
with the use of heat and pressure, characterized in that polyethylene 
having a melt index of less than 0.15 is used. The polyethylene is 
preferably applied in powder form to the surface of the rubber before the 
exertion of pressure and exposure to heat. However, the polyethylene can 
also be applied in the form of a film. 
It is known from DOS (German Unexamined Laid-Open Application) No. 
2,004,379 to establish adhesive bonds between vulcanized layers of 
elastomeric copolymers and/or terpolymers of ethylene with an 
.alpha.-olefin and a selective polyene and/or butyl rubber, if there is 
inserted between these elastomeric layers a plastomeric layer of a 
thermoplastic polymer and/or copolymer of ethylene, propylene and/or 
butene which is free of substituent groups having a polar character and 
free of reactive groups, and the thus-combined layers are subjected to the 
effect of heat, preferably under pressure. 
Finally, a process is known from DOS No. 2,322,594 for bonding a molded 
article of an ethylene/propylene copolymer rubber (EPM) or an 
ethylene/propylene/diolefin copolymer rubber (EPDM) with a polyolefin 
resin. 
All of the processes and/or measures of the above-discussed state of the 
art, however, exhibit more or less serious practical deficiencies. For 
example, it is only possible by means of the process according to DOS No. 
2,322,594 to join molded articles of an ethylene/propylene or 
ethylene/propylene/diene copolymer with an article of a thermoplastic 
material (synthetic polyolefin resin), but it is impossible thereby to 
connect molded articles of EPM or EPDM with each other. 
The use of pulverulent polyolefin hot-melt adhesives according to DOS No. 
1,620,832 has the disadvantage, above all during the sealing of rubber 
roofing sheets, that the powder frequently does not remain at the point 
provided for the heat-sealing step due to the inclination of the roof, 
wind and the heat-sealing device used for the welding step. The use of 
very thin film strips according to DOS's Nos. 1,620,832 and 2,004,379 is 
often made difficult for the same reason. 
When using film strips of a polyolefin, four surfaces must be heated almost 
uniformly and must be held in the correct position. A previously conducted 
strip-shaped coating of the roofing sheets to be glued together at the 
zones intended for the welding step is possible, but unsatisfactory since 
additional welds are necessary in view of the deviations from the laying 
pattern (chimneys, eaves, etc.) unavoidable under practical conditions. 
When using polyolefin film strips, there is the additional danger that 
individual droplets are formed during the complete melting of the 
polyolefin, leading to a non-uniform and thus leaking weld. 
OBJECTS OF THE INVENTION 
Accordingly, it is a general object of the present invention to provide 
polyolefin or butyl rubber vulcanizates which overcome the aforementioned 
deviciencies of the prior art. 
Another object of this invention is to provide polyolefin or butyl rubber 
vulcanizates which are readily heat-sealable at temperatures sufficiently 
low for practical outdoor use, particularly in the construction industry. 
A further object of the present invention is to provide polymer blends 
suitable for forming the above-mentioned vulcanizates. 
Upon study of the specification and appended claims, further objects and 
advantages of this invention will become apparent to those skilled in the 
art. 
SUMMARY OF THE INVENTION 
Briefly, the above and other objects, features and advantages of the 
present invention are attained in one aspect thereof by providing, in a 
heat-sealable polyolefin elastomer vulcanizate comprising: 
(a) a polyolefin elastomer selected from the group consisting of EP 
copolymers of ethylene with at least one of propylene and butene-1, EPDM 
copolymers of ethylene and at least one of propylene and butene-1, with an 
unconjugated diene, and elastomeric copolymers of isobutylene and 
isoprene; and 
(b) a cross-linking amount of an elastomer cross-linking agent, the 
improvement which comprises: 
5-100 parts by weight, based on said polyolefin elastomer, of a propylene 
polymer uniformly admixed therewith prior to vulcanization which is 
selected from the group consisting of polypropylene and copolymers of 
propylene with up to 20% by weight of ethylene, butene-1, or hexene-1 
which polymer has a heptane-extractable portion of 5-60%, an I-value 
measured according to DIN 53 728 of 100-600 cm.sup.3 /g. and a yield point 
measured according to DIN 53 735 of 10-30 N/mm.sup.2. 
DETAILED DISCUSSION 
It has now been found that it is possible to permanently heat-seal 
vulcanizates on the basis of polyolefin rubbers in a simple manner, namely 
merely with the use of heat, if they contain the compositions of the 
present invention. 
Within the scope of this invention, vulcanizates of polyolefin elastomers 
are understood to mean shaped articles, primarily sheets or films, 
comprising ethylene-propylene and/or butene-1 co- or terpolymers, 
ethylene-propylene and/or butene-1-unconjugated diene ter- or 
quaterpolymers or isobutylene-isoprene copolymers. 
Preferred polyolefin elastomers useful for preparation of the heat-sealable 
vulcanizates according to this invention are saturated polyolefin 
elastomers comprising 15-90% by weight, preferably 30-75% by weight, of 
ethylene and correspondingly 85-10% by weight, preferably 70-25% by 
weight, of propylene and/or butene-1. Also preferred are unsaturated 
polyolefin elastomers comprising, in addition to ethylene, propylene 
and/or butene-1 within the limits just indicated for the saturated 
polyolefin elastomers, a multiple olefin in such an amount that the 
elastomers contain 0.5-30 double bonds per 1000 carbon atoms. Especially 
preferred multiple olefins are cis- and trans-1,4-hexadiene, 
dicyclopentadiene, 5-methylene-, 5-ethylideneand 
5-isopropylidene-2-norbornene. These polymers can be prepared in 
accordance with conventional prior-art processes, e.g. as described in 
DAS's Nos. 1,570,352; 1,595,442; and 1,720,450. 
The butyl rubber usable in accordance with this invention can also be 
produced by conventional techniques, e.g. according to the method of 
French Patent No. 1,508,766. 
The polypropylenes and/or copolymers of propylene with up to 20% by weight 
of ethylene, butene-1 or hexene, which are specific and essential to this 
invention, can be readily obtained by the polymerization of propylene, 
optionally with ethylene and/or butene-1 and/or 1-hexene as the 
comonomers, with the aid of a mixed titanium-aluminum chloride catalyst of 
the composition TiCl.sub.3 . nAlCl.sub.3 (n = 0.2-0.6), which is produced, 
for example, by the reduction of titanium tetrachloride with metallic 
aluminum or organoaluminum compounds, and further containing an 
organoaluminum compound. In particular, a thermally unstable 
titanium-aluminum chloride in the .gamma.- or .delta.-modification is 
useful which loses, at temperatures of up to 250.degree. C., the largest 
portion of the aluminum chloride. Catalyst activation is preferably 
accomplished with dialkyl aluminum halides, especially with dialkyl 
aluminum chlorides. Below a polymerization temperature of 50.degree. C., 
it is also possible to use preferably aluminum trialkyls and aluminum 
dialkyl hydrides. Other suitable halogen-containing organoaluminum 
compounds are the alkyl aluminum sesquihalides and the alkyl aluminum 
dihalides, but these are used in combination with electron donors. The 
chlorides are preferably employed. Mixtures of the various alkyl aluminum 
compounds are also suitable, e.g. mixtures of aluminum trialkyls with 
dialkyl aluminum chlorides. 
The titanium-trichloride-containing catalysts are preferably used in a 
concentration of 0.1-10 millimoles/liter of liquid phase and at a molar 
ratio of Al:Ti of 1-3:1, preferably 1.5-2.5:1. 
The polymerization is conducted at temperatures of up to 100.degree. C., 
preferably 30.degree.-90.degree. C., especially 50.degree.-80.degree. C., 
in any of the inert hydrocarbon diluents known to be suitable in 
polymerization with the aid of Ziegler-Natta catalysts, as well as in 
excess liquid monomers as the diluent. Preferably, the propylene is 
polymerized in C.sub.4 -cuts, which contain butene-2 in addition to butane 
and butene-1. The butene-2 accelerates the polymerization and improves the 
copolymerization of butene-1 with propylene, as is more particularly 
described in Federal Republic of German Application DOS No. 2 338 478. 
Further suitable comonomers are ethylene and hexene-1. The comonomer or 
comonomers, which may be present in the polymer to an extent of up to 20% 
by weight, are preferably added together with the propylene, since in this 
way copolymers having a statistically random distribution of the monomer 
units, which are considered to be preferred, are obtained. 
The polymerization can be conducted continuously and/or discontinuously. 
For molecular weight regulation purposes, hydrogen can be utilized, as is 
known. 
The polypropylenes and/or copolymers of propylene with up to 20% by weight 
of ethylene, butene-1 or hexene-1 which are usable in accordance with this 
invention have a heptane-extractable proportion of 5-60%, preferably 
8-45%, an I-value of 100-600 cm.sup.3 /g., preferably 150-500 cm.sup.3 
/g., especially 200-400 cm.sup.3 /g., and a yield point of 10-30 
N/mm.sup.2, preferably 16-28 N/mm.sup.2, especially 20-26 N/mm.sup.2. They 
are added to the polyolefin elastomers prior to vulcanization in an amount 
of 5-100 parts by weight, preferably 15-60 parts by weight, and especially 
20-40 parts by weight, based on 100 parts by weight of polyolefin rubber. 
Normally, the mixing can be conducted, without needing a separate working 
step, simultaneously with the incorporation of the additives customary in 
rubber technology, e.g. by means of a rolling mill or an internal mixer, 
advantageously at a temperature ranging above the melting point of the 
polyolefin used and not exceeding 250.degree. C., preferably not exceeding 
200.degree. C. Subsequently, the vulcanizing agents are then incorporated 
at temperatures where the mixture has not yet commenced the vulcanizing 
reaction. 
A particularly suitable vulcanizing agent is sulfur in combination with one 
or more conventional vulcanization accelerators with the addition of zinc 
oxide and higher fatty acids, e.g. stearic acid. Peroxides or special 
sulfur donors, e.g. N,N'-morpholine disulfide or special thiurams, can be 
used with the same success for cross-linking purposes. 
Advantageous additives are the conventional active fillers and 
plasticizers. Suitable fillers are carbon blacks of all stages of 
activity, as well as the customarily usable mineral products, e.g. chalk, 
silicates and highly active silicic acids. The plasticizers employed are 
the conventional refinery products; oils having primarily aromatic, 
naphthenic or paraffinic components can be used. Furthermore, all 
conventional antiaging substances can, of course, also be added. 
The subsequent conductance of the cross-linking reaction in presses, 
autoclaves, etc. does not require any special measures. 
The vulcanizates of this invention can be heat-sealed with one another as 
well as with vulcanizates of other polyolefin elastomers which do not 
contain the addition of the specific polypropylene or copolymer of 
propylene within the scope of this invention with up to 20% by weight of 
ethylene, butene-1 or 1-hexene. Moreover, heat-sealing is likewise 
possible with specific unvulcanized polyolefin elastomers, namely the 
so-called sequence or block polymers. These are ethylene-.alpha.-olefin 
copolymers and/or ethylene-.alpha.-olefin-diene terpolymers containing 
ethylene or one of the .alpha.-olefins in addition to a statistically 
random distribution of the monomers in the polymer chain in the form of 
differently long chain sequences, e.g. as described in Federal Republic of 
Germany Application DOS No. 2 427 343. 
The heat-sealing step, which is generally conducted at the site where the 
product is used, is accomplished, for example, by heating the vulcanizates 
to be welded together, e.g. in the form of panels, profiles or sheets at 
the appropriate locations (free of parting agent), e.g. by means of a 
hot-air blower, to a temperature above the melting point of the polyolefin 
utilized; placing the heated parts to be joined one on top of the other, 
and applying pressure thereon, e.g. with a pressure roll. Suitably, the 
welded-together parts are maintained under pressure until they have cooled 
down to room temperature. 
Without further elaboration, it is believed that one skilled in the art 
can, using the preceding description, utilize the present invention to its 
fullest extent. The following preferred specific embodiments are, 
therefore, to be construed as merely illustrative and not limitative of 
the remainder of the disclosure in any way whatsoever. In the following 
Examples, the temperatures are set forth uncorrected in degrees Celsius; 
unless otherwise indicated, all parts and percentages are by weight. In 
all of the Examples, at least two layers are bonded by heat-sealing. 
However, it will be apparent that basically any desired number of layers 
can be welded together in an analogous fashion. 
The characteristic values indicated in the Examples were measured in 
accordance with the following methods and DIN (German Industrial Standard) 
norms, respectively: 
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I-value in cm.sup.3 /g.: 
measured on a 0.1% solution in 
"Decalin" (decahydronaphthalene) 
at 135.degree. C. according to DIN 53 728 
Heptane-extractable 
measured by the weight 
difference after 
proportion in %: 
extraction with boiling heptane 
Yield point in N/mm.sup.2 
= MPa (mega-Pascals): 
measured according to DIN 53 735 
Tear strength in N/mm.sup.2 : 
measured according to DIN 5s 735 
Elongation at rupture 
(ultimate elongation) in %: 
measured according to DIN 53 735 
Notch impact strength in 
kJ/m.sup.2 (kilo-Joules per 
measured according to DIN 53 453 
square meter): 
MFI.sub.190/5 value in gl/10' 
(grams per 10 minutes): 
measured according to DIN 53 735 
Tensile strength in N/mm.sup.2 : 
measured according to DIN 53 504 
Elongation at yield in %: 
measured according to DIN 53 504 
Modulus at 200% elongation 
in N/mm.sup.2 : measured according to DIN 53 504 
Tear propagation resistance 
in N/mm: measured according to Pohle 
Hardness at 22.degree. C. in 
.degree. Shore A: 
measured according to DIN 53 505 
Impact elasticity in %: 
measured according to DIN 53 512 
Resistance to peeling 
in N/mm: measured according to DIN 53 274 
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EXAMPLE 1 
Production of a Propylene-Butene-1 Copolymer 
With the aid of a mixed catalyst made of 0.02 part by weight of a 
TiCl.sub.3 catalyst having the composition TiCl.sub.3 . 0.33 AlCl.sub.3 
(primarily the .delta.-modification, commercially available 
aluminum-reduced titanium trichloride) and 0.03 part by weight of 
diethylaluminum chloride, 20 parts by weight of propylene (99% pure) is 
polymerized in 50 parts by weight of a butene-2-butene-1-butane mixture of 
39.2% trans-butene-2, 19.8% cis-butene-2, 39.8% n-butane, 1.0% butene-1 
and 0.2% isobutene at 50.degree. C. after the addition of 0.0002 part by 
weight of hydrogen under a pressure of 10-7 bars. After a polymerization 
period of 4 hours, the polymerization is short-stopped by adding 0.1 part 
by weight of steam. By expanding the suspension through nozzles, 18.5 
parts by weight of a powdery propylene-butene-1 copolymer is obtained 
having the following characteristic values: 
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I-value: 330 cm.sup.3 /g. 
MFI.sub.190/5 : 3.8 g./10' 
Heptane extract: 11% 
Yield point: 22.3 N/mm.sup.2 
Tear strength: 31.8 N/mm.sup.2 
Ultimate elongation: 758% 
Notch impact strength: 
20.degree. C. 24.2 kJ/m.sup.2 
0.degree. C. 10.1 kJ/m.sup.2 
-20.degree. C. 5.6 kJ/m.sup.2 
______________________________________ 
The copolymer was used together with other polypropylenes during the tests 
reported in Examples 3-8 to investigate the heat-sealability of EPDM 
rubber vulcanizates. 
EXAMPLE 2 
Production of a Heat-Sealable Vulcanizate of EPDM Rubber 
At a temperature of 180.degree. C., a homogeneous mixture of the following 
components was prepared on a laboratory rolling mill having a size of 200 
.times. 450 mm. at a friction of 1:1.12: 
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Parts by Weight 
______________________________________ 
Ethylene-propylene-5-ethylidene-2- 
norbornene terpolymer ("BUNA" AP 541) 
100 
Polypropylene (I-value: 250 cm.sup.3 /g.; 
heptane-extractable proportion: 
42.3%; yield point: 20.5 N/mm.sup.2) 
40 
Stearic acid 1 
Zinc oxide 5 
Carbon black N 550 130 
Siliceous chalk ("Sillitin" N) 
30 
Mineral oil ("Gulf" Oil 2212) 
70 
______________________________________ 
After cooling of the mixture, the following vulcanization system was 
incorporated therein at 50.degree. C.: 
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Parts by Weight 
______________________________________ 
Sulfur 0.6 
Tetramethylthiuram monosulide 
0.5 
Dibenzothiazyl disulfide 
1.0 
Dicyclohexylammonium-O,O'-diisobutyl- 
dithiophosphate 1.0 
Zinc N-di-n-butyldithiocarbamate 
1.0 
______________________________________ 
The thus-obtained mixture was thereafter heated for 10 minutes in a 
vulcanizing press at 200 bars to 170.degree. C. and pressed in a mold into 
panels having a thickness of 2 mm. for the heat-sealing tests. The 
vulcanizate (called vulcanizate A in the following Table 1 and a portion 
of the subsequent experiments) had the following mechanical properties: 
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Tensile strength 13.3 N/mm.sup.2 
Elongation at yield 440% 
Modulus at 200% elongation 
8.4 N/mm.sup.2 
Tear propagation resistance 
3 N/mm. 
Hardness 76.degree. Shore A 
Impact elasticity 31% 
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The vulcanizate did not show any cracks at an elongation of 20%, after 
being exposed to ozone in a concentration of 200 p.p.m. for 7 days. 
COMATIVE EXAMPLE 1 
Vulcanizate B was produced in accordance with the description of Example 2, 
the only difference being that the polypropylene of Example 2 was replaced 
by a commercially available, isotactic polypropylene (I-value 400 cm.sup.3 
/g., practically insoluble in heptane, yield point 33.4 N/mm.sup.2). 
COMATIVE EXAMPLE 2 
For producing vulcanizate C, Example 2 was modified in two aspects. First, 
the roll temperature was lowered from 180.degree. C. to 150.degree. C. 
Second, rather than using 40 parts by weight of polypropylene, there was 
used 40 parts by weight of a practically heptane-insoluble low-pressure 
polyethylene having an I-value of 420 cm.sup.3 /g. 
Test for Heat-Sealability 
To test the heat-sealability, strips of vulcanizates A through C, having a 
length of 150 mm., a width of 30 mm. and a thickness of 2 mm., were 
heat-sealed in accordance with DIN 53 274. In order to arrive at 
comparable values, the heat-sealing step was carried out for 5 minutes at 
170.degree. C. or 140.degree. C., in a customary vulcanizing press rather 
than by hand, at 5 bars; thereafter, the specimens were tested for peeling 
resistance at room temperature (20.degree. C.) or at 70.degree. C. in a 
customary tearing machine with a diagram writer connected thereto, with a 
feed rate of 100 mm./min. The peeling resistance of the test resulting 
from the diagram as an average value plotted over the parting distance is 
indicated in N/mm. The results can be seen from Table 1. 
TABLE 1 
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Vulcanizate A B C 
______________________________________ 
Heat-sealing 
temperature, .degree. C. 
140 170 140 170 140 170 
Peeling resistance 
in N/mm. (average 
value over the 
parting distance 
at 22.degree. C. 
4.1 4.9 0.3 2.2 1.0 2.8 
at 70.degree. C. 
1.0 2.5 ca. ca. 
0.03 0.3 0.15 0.9 
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EXAMPLES 3-8 
With the aid of these Examples, the effect of the change of molecular 
parameters of the polypropylene and/or the copolymers of propylene usable 
according to this invention (e.g. heptane extractable proportion, I-value 
and yield point) and the effect of the amount mixed-in on heat-sealability 
can be demonstrated. 
The vulcanizates were produced according to the method of Example 2; the 
test was carried out as described for vulcanizates A through C. The 
results are shown in Table 2. 
TABLE 2 
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Example 3 4 5 6 7 8 
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Parts by weight of 
polypropylene based 
on 100 parts by 
weight of EPDM 20 40 20 40 60 40 
Heptane-extract- 
able proportion 
(%) 11 11 44 44 44 21 
I-Value cm.sup.3 g. 
330 330 230 230 230 440 
Yield point N/mm.sup.2 
22.3 22.3 18.8 18.8 18.8 22.2 
Peeling resistance 
N/mm (average value 
over parting dist- 
ance) 
at 22.degree. C. 
3.4 4.2 5.8 5.2 4.7 4.6 
at 70.degree. C. 
1.5 1.9 2.6 2.0 1.7 1.5 
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EXAMPLE 9 
At a roll temperature of 180.degree. C., 100 parts by weight of a saturated 
ethylene-propylene rubber (49% ethylene, 51% propylene, Mooney viscosity 
40) and 40 parts by weight of the polypropylene according to Example 5 
were homogeneously mixed. After cooling of the mixture, the following 
substances were incorporated at a roll temperature of 50.degree. C.: 
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Zinc oxide 7.5 parts by weight 
Carbon black N 774 65 " 
Mercaptobenzimidazole 
1 " 
1,3-bis(tert.-butyl- 
peroxyisopropyl)benzene 
3 " 
Triallyl cyanurate 1 " 
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The thus-obtained mixture was heated for 20 minutes in a vulcanizing press 
at 200 bars to 170.degree. C. and pressed into panels having a thickness 
of 2 mm. for testing heat-sealability. The thus-produced vulcanizate had 
the following mechanical properties: 
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Tensile strength 11.8 N/mm.sup.2 
Elongation at yield 351% 
Modulus at 200% elongation 
8.1 N/mm.sup.2 
Tear propagation resistance 
25 N/mm. 
Hardness at 22.degree. C. 
73.degree. Shore A 
Impact elasticity 42% 
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The heat-sealing and testing for peeling resistance in connection with 
these vulcanizates took place as described for vulcanizates A through C. 
The results are set forth in Table 3. 
EXAMPLE 10 
At a roll temperature of 180.degree. C., 100 parts by weight of butyl 
rubber ("Enjay Butyl" 365 of Exxon) and 40 parts by weight of 
polypropylene of the type indicated in Example 5 were mixed homogeneously. 
After cooling, the following vulcanizing agents and additives were 
furthermore incorporated at a roll temperature of 40.degree. C.: 
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Chalk 70 parts by weight 
Carbon black N 550 
50 " 
Silicate filler (70% SiO.sub.2) 
15 " 
Ozocerite (hydrocarbon wax) 
5 " 
Magnesia usta, light 
5 " 
Stearic acid 1.5 " 
Zinc oxide 5 " 
Sulfur 1.25 " 
Tetramethylthiuram disulfide 
1.5 " 
2-Mercaptobenzothiazole 
2.0 " 
N,N'-Morpholine disulfide 
1.25 
______________________________________ 
The thus-obtained mixture was heated for 20 minutes in a vulcanizing press 
at 200 bars to 150.degree. C. and pressed into panels having a thickness 
of 2 mm. in order to test heat-sealability. The thus-produced vulcanizate 
had the following mechanical properties: 
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Tensile strength 82 N/mm.sup.2 
Elongation at yield 350% 
Modulus at 200% elongation 
64 N/mm.sup.2 
Tear propagation resistance 
18 N/mm. 
Hardness at 22.degree. C. 
85.degree. Shore A 
Impact elasticity 14% 
______________________________________ 
The heat-sealing step and the test for peeling resistance were carried out 
as described for vulcanizates A through C. The results are shown in Table 
3. 
EXAMPLE 11 
Vulcanizate A was heat-sealed to a vulcanizate which did not contain the 
addition of polypropylene according to this invention and which had the 
composition set forth below, in accordance with the description for 
vulcanizates A through C: 
______________________________________ 
Ethylene-propylene-5- 
ethylidene-2-norbornene 
terpolymer ("BUNA" AP 541) 
100 parts by weight 
Stearic acid 1 " 
Zinc oxide 5 " 
Carbon black N 330 50 " 
Mineral oil ("Gulf" Oil 2212) 
10 " 
Tetramethylthiuram disulfide 
1 parts by weight 
2-mercaptobenzothiazole 
0.5 " 
Sulfur 1 " 
______________________________________ 
The heat-sealing step and the test for peeling resistance were carried out 
as indicated for vulcanizates A through C. The results are shown in Table 
3. 
EXAMPLE 12 
Strips of the vulcanizate A were heat-sealed by means of a hot-air device 
having a nozzle of a width of 30 mm. at a hot-air temperature of about 
300.degree. C. for approximately 1 minute while applying pressure with a 
rubber roller. The peeling resistance was tested as described in detail in 
connection with vulcanizates A through C. The results are set forth in 
Table 3. 
TABLE 3 
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Example 9 10 11 12 
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Heat-Sealing Conditions 
5' at 5' at 5' at 1' at about 
170.degree. C. 
170.degree. C. 
170.degree. C. 300.degree. C. 
5 bars 5 bars 5 bars 
Rubber 
Roller 
Peeling Resistance N/mm. 
(Average Value over the 
Parting Distance) 
at 22.degree. C. 
7.0 4.6 4.6 4.8 
at 70.degree. C. 
3.6 1.2 1.4 1.7 
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The preceding examples can be repeated with similar success by substituting 
the generically or specifically described reactants and/or operating 
conditions of this invention for those used in the preceding examples. 
From the foregoing description, one skilled in the art can easily ascertain 
the essential characteristics of this invention and, without departing 
from the spirit and scope thereof, can make various changes and 
modifications of the invention to adapt it to various usages and 
conditions.