Polymer compositions and a method for enhancement in phase compatibility of elastomers with relatively rigid polymers

Thermoplastic compositions are disclosed which contain, as principle ingredients, a relatively rigid polymer, such as polyvinyl chloride and/or chlorinated polyvinyl chloride and an EPM and/or an EPDM type elastomer. In addition to the above components, the composition can have incorporated therein a phase compatibility promotion agent, such as chlorinated polyethylene or poly(ethylene-co-vinyl acetate), or mixtures thereof. This phase compatibility promotion agent helps insure more uniform distribution of the elastomer throughout the relatively rigid polymer and improved cohesion of the resultant composition. Also disclosed are methods for enhancement in the compatibility of relatively rigid polymers and elastomers through the use of such phase compatibility promotion agents.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is directed to polymer compositions and a method. More 
specifically, this invention concerns itself with the alleviation of 
problems associated with the preparation of blends from two or more 
essentially incompatible polymeric materials, such as relatively 
inflexible polyvinyl chloride or chlorinated polyvinyl chloride and 
ethylene-propylene (EPM) elastomers or ethylene-propylene-diene (EPDM) 
elastomers. 
2. Description of the Prior Art 
The prior art is replete with references which describe various means and 
methods for enhancement of the impact resistance of relatively rigid 
thermoplastics such as polyvinyl chloride (hereinafter PVC) and 
chlorinated polyvinyl chloride (hereinafter CPVC)--see for example U.S. 
Pat. No. 3,299,182 which discloses blends of CPVC and chlorinated 
polyethylene. Acrylonitrile/butadiene/styrene (ABS) compositions can also 
be modified in a similar fashion, see for example, U.S. Pat. No. 
3,887,648. As disclosed in the above patents, these relatively rigid 
polymers can be compounded with one or more elastomers or mixtures of 
elastomers or other functionally similar material, each of which being 
tailored to impart improved processing and/or improved end-use 
characteristics of the rigid polymer. Typically, these elastomers contain 
a pendant group or a segment within their backbone which is common to or 
has improved compatibility with the rigid polymer (see, for example, U.S. 
Pat. Nos. 4,021,508; 3,994,995; 3,906,059; 3,891,725; and 4,035,440). The 
relatively rigid polymer can be combined with the elastomeric materials by 
dry blending (U.S. Pat. No. 3,994,995) or by the in situ polymerization of 
a vinyl monomer in the presence of an EPDM type elastomer, (U.S. Pat. No. 
3,906,059). 
Two component thermoplastic blends of certain EPM or EPDM elastomers with 
other thermoplastic olefins are known to form homogeneous easily moldable 
compositions which can be formed into tough flexible articles (see U.S. 
Pat. Nos. 3,919,358 and 4,036,912). Ordinarily, such blends lack intrinsic 
flame resistant properties, exhibit poor adhesion to polar substrates and 
cannot be dielectrically sealed. It is hypothesized that many of these 
deficiencies could be overcome if certain EPM or EPDM elastomers were to 
be blended with chlorine containing thermoplastic, such as PVC or CPVC. 
Prior attempts at combining such materials have proven largely 
unsuccessful due to the relative incompatibility between such materials. 
Such incompatibility can reportedly be overcome where the PVC is 
chemically engrafted upon the elastomer. This grafting process is 
economically unattractive. 
Certain chlorinated polyethylene (CPE) elastomers have been found to be 
suitable for enhancement in the impact resistance of PVC and CPVC for some 
specific applications, (see for example U.S. Pat. Nos. 3,994,995 and 
3,856,891). The chlorinated polyethylenes are not, however, acceptable 
substitutes for the EPM and EPDM type elastomers in PVC and CPVC. The 
reason for this lack of equivalency is quite simple, namely, the glass 
transition temperature (T.sub.g) of chlorinated polyethylene is about 
5.degree. F.; whereas, the glass transition temperature (T.sub.g) of EPM 
and EPDM elastomers is about -60.degree. F. It is thus readily apparent 
that the EPM and EPDM elastomers are superior for enhancing the impact 
resistance of thermoplastics such as PVC and CPVC over a broader 
temperature range since the thermoplastics which are compounded with EPM 
and EPDM elastomers retain their impact resistance at much lower 
temperatures. 
It would thus appear from the above discussion, that there is a continuing 
need for enhancement in the impact resistance of thermoplastic materials 
such as PVC and CPVC over broad temperature ranges and that the blends 
which are currently available do not retain such impact resistance at 
depressed temperatures. 
SUMMARY OF THE INVENTION 
Accordingly, it is the object of this invention to remedy the above as well 
as related deficiencies in the prior art. 
More specifically, it is the principal object of this invention to provide 
a thermoplastic composition having improved low temperature flexure and 
impact resistance in addition to enhanced flame resistance, adhesion to 
polar substrates and dielectric sealability. 
It is another object of this invention to provide an improved thermoplastic 
PVC and/or CPVC polymer composition having improved low temperature 
flexure and impact resistance in addition to enhanced flame resistance, 
adhesion to polar substrate and dielectric sealability. 
Another object of this invention is to provide a thermoplastic PVC and/or 
CPVC composition having improved low temperature flexure and impact 
resistance while maintaining its coherent character. 
Still yet a further object of this invention is to provide a method for 
enhancing the phase compatibility of elastomeric materials such as EPDM 
and EPM type elastomers in PVC and/or CPVC. 
The above and related objects are achieved by providing a coherent 
thermoplastic composition containing (a) from about 20 to about 70 weight 
percent PVC and/or CPVC, (b) from about 10 to about 50 weight percent EPM 
and/or EPDM type elastomers and (c) from about 10 to about 60 weight 
percent chlorinated polyethylene. In one of the alternative embodiments of 
this invention poly(ethylene-co-vinylacetate) can be substituted for a 
portion of the chlorinated polyethylene component. The chlorinated 
polyethylene and/or poly(ethylene-co-vinyl acetate) apparently enhance the 
compatibility of the elastomer with the vinyl material thereby forming a 
coherent thermoplastic polymer composition having the attributes of a 
thermoplastic and the impact resistance of an elastomer at low 
temperatures (eg below 0.degree. C.).

DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS 
The compositions of this invention can be prepared by dry blending a 
relatively rigid polymer, such as polyvinyl chloride and/or chlorinated 
polyvinyl chloride with an EPM and/or EPDM type elastomer, in the 
appropriate relative proportion, and an agent capable of promoting the 
phase compatibility of this elastomer with the rigid polymer. The phase 
compatibility promotion agent can include a chlorinated polyethylene or a 
copolymer of ethylene and vinyl acetate, or mixtures thereof. Ordinarily, 
less than half the chlorinated polyethylene should be substituted by the 
vinylacetate copolymer in the environment of contemplated use, however, 
there may be exceptions. These materials can be combined with one another 
employing conventional techniques and equipment. 
The vinyl chloride polymers suitable for use in the compositions of this 
invention are readily available commercially, or can be prepared by 
techniques and with equipment disclosed in the open literature. Similarly, 
the chlorinated vinyl chloride polymers suitable for use in the 
compositions of this invention are also readily available commercially or 
can be prepared by techniques disclosed in the open literature, (e.g. U.S. 
Pat. No. 3,100,762). The chlorine content of the latter polymers typically 
can range from about 65 to 75 weight percent. 
The elastomers suitable for use in the composition of this invention, as 
indicated previously, are the EPDM or EPM type materials. These elastomers 
can be oil extended or non-oil extended. Literature references disclosing 
the preparation of these materials indicate that they can be prepared by 
polymerizing ethylene and at least one other .alpha.-olefin containing 3 
to 6 carbon atoms (e.g. polypropylene or butene-1). The typical EPDM type 
elastomer utilized herein is a copolymer, can have an ethylene content of 
from about 60 to about 85 weight percent, an .alpha. olefin content of 
from about 5 to about 40 weight percent and a polyene content of from 
about 0.5 to about 20 weight percent. The polyene of the EPDM type 
elastomers is ordinarily a conjugated diene such as isoprene, butadiene, 
chloroprene and the like; a non-conjugated diene; a triene, or a higher 
enumerated polyene. The nonconjugated dienes containing from about 5 to 25 
carbon atoms are most preferred. Examples of such nonconjugated dienes 
are, 1,4-hexadiene, ethylidenenorbornene, dicyclopentadiene, 
methyltetrahydroindene, and the like. In the preferred embodiments of this 
invention, the EPDM type elastomers will ordinarily contain from about 65 
to 80 weight percent ethylene; from about 20 to 35 weight percent 
propylene; and, from about 1 to about 10 weight percent nonconjugated 
diene. These elastomers ordinarily will range in molecular weight from 
2.times.10.sup.4 to 2.times.10.sup.6, and in certain instances, in excess 
of that upper figure. Typically, they will have dilute solution 
viscosities (DSV) from about 1 to about 5, measured at 25.degree. C. (0.2 
grams of polymer in 100 milliters of toluene). In measuring DSV of 
elastomers with molecular weights above 1 million, a solution of 0.1 gram 
polymer in 100 milliters of toluene is generally employed. 
The EPM type elastomers of the composition of this invention are copolymers 
of ethylene and propylene. The ethylene content of such elastomers is 
ordinarily in the range from about 60 to 85 weight percent with the 
remainder of the polymer consisting essentially of polypropylene, poly 
1-butene, and the like. Preferably, such EPM type elastomers will have an 
ethylene content of from 65 to about 80 weight percent and most preferably 
from about 65 to 75 weight percent with the remainder of the polymer 
consisting essentially of propylene. 
The EPM copolymers suitable for use in the blends of this invention will 
have a molecular weight of from about 20,000 to in excess of 2 million. 
The dilute solution viscosities of such materials will range from about 1 
to about 5, measured at 25.degree. C. (in a solution consisting of 0.2 
grams polymer and 100 milliliters toluene). 
Phase compatiblizing agents suitable for use in conjunction with the 
foregoing materials can comprise halogenated polyolefins such as 
chlorinated polyethylene or copolymers of ethylene and vinyl acetate and 
mixtures thereof. 
The halogenated polyolefins, such as chlorinated polyethylene, suitable for 
use in this invention are commercially available or can be prepared by 
techniques which are disclosed in the open literature, see for example 
U.S. Pat. No. 3,856,891, which is hereby incorporated by reference in its 
entirety. According to the above patent, chlorinated polyethylene can be 
obtained by a chlorinated procedure which comprehends the suspension 
chlorination, in an inert medium, of finely divided essentially linear 
polyethylene, and interpolymers containing at least 90 mole percent 
ethylene with the remainder being one or more ethylenically unsaturated 
comomoners. The degree of chlorination will ordinarily be dependent upon 
the temperature and the duration of the processing sequence. In the 
preferred embodiments of this invention the chlorinated polyethylene, 
prepared as described above, has chlorine content in the range of from 
about 10 to about 50 weight percent and most preferably from about 25 to 
about 50 weight percent. 
The ethylene-vinyl acetate copolymers which can be also present in the 
compositions, and employed in the methods of this invention, are 
commercially available or can be prepared from readily available materials 
by techniques disclosed in the open literature. The relative proportion of 
the monomers in such copolymer is critical to its performance in the 
instant invention, and the concentration of structural units contributed 
by the vinyl acetate relative to ethylene in the copolymer should be in 
the range of from about 5 to 45 weight percent. In the preferred 
embodiment of this invention, the vinyl acetate derived component of the 
copolymer should be in the range of from 20 to 40 weight percent. As 
indicated herein, the vinyl acetate copolymer can be used in conjunction 
with the chlorinated polyethylene however not as a total replacement 
thereof. In the preferred embodiment of this invention, the ratio of 
chlorinated polyethylene to ethylene vinyl acetate copolymer can range 
from about 5:1 to about 1:5. 
The various components of the compositions of this invention can be 
prepared by simply mixing the individual ingredients of such composition, 
in the appropriate relative proportions, in a roll-mill or a Banbury 
mixer. In a typical mixing operation, the dry-blend of the composition is 
placed upon preheated rollers (approximately 365.degree. F.) and the 
ingredients fluxed for about 10 minutes. In a Banbury mixing operation, 
the dry ingredients would be placed in a Banbury equipped with a heated 
jacket (approximately 370.degree. F.) and mixed for approximately 3-5 
minutes. The molten mass would then be sheeted on a mill and the resultant 
sheet thereafter ground into fine particles. In addition to the specified 
ingredients of the foregoing composition, other optional materials, such 
as those disclosed in U.S. Pat. No. 4,036,912 (Col. 4, line 39 to Col. 5, 
line 2) can also be incorporated therein at levels well-known to those 
skilled in the art. 
Once the composition has been prepared, an appropriate amount thereof can 
be placed on an ASTM tensile sheet mold and compression molded. In a 
typical molding operation, the ASTM sheet mold is approximately six inches 
square by 75 mils. The processing cycle involves compression of the sample 
at approximately 1000 psi at 360.degree. F. for 10 minutes. Subsequent to 
the completion of the molding cycle, the molded plaque is placed between a 
pair of water-cooled platens and quenched for about a period of 5 minutes. 
The physical properties of the samples prepared in the above manner are 
evaluated for stress/strain according to ASTM D 412 procedure (at a rate 
of elongation equivalent to 20 inches per minute); and the result of such 
evaluation presented in the following tables. 
__________________________________________________________________________ 
POLYMERS AND ADDITIVES USED IN THE FOLLOWING EVALUATION 
__________________________________________________________________________ 
Ethylene-propylene-(ethylidene norbornene) rubber (BF Goodrich Co.) 
R.T. Tensile Properties 
Wt. % 125.degree. C. 
100% Strength 
Density 
C.sub.2 
Wt. % ENB 
ML Mod., psi 
psi at Break 
__________________________________________________________________________ 
Epcar 847 
.88 71 4 55 230 1200 800 
Epcar 807 
.88 74 0 55 240 865 750 
Epcar 305 
.87 55 0 20 50 50 low 
__________________________________________________________________________ 
Chlorinated Polyethylenes (Dow Chemical Co.).sup.(a) 
R.T. Tensile Properties 
Wt. % 
Viscosity 
100% Strength 
% Elong. 
Density 
Cl Poise Mod. psi 
psi at Break 
__________________________________________________________________________ 
CPE 2243-49 
1.22 40 19500 350 2300 475 
CPE 2243-45 
1.18 36 10000 200 1600 700 
CPE 3623 
1.16 34 16000 200 1500 700 
CPE 2552 
1.10 26 1300 
__________________________________________________________________________ 
Tensile at 
Density 
Ethylene-vinyl acetate 
% VA 
MI Yield, psi 
g/cc 
__________________________________________________________________________ 
USI 
UE 636 28 20 1000 
Union Carbide 
EVA 607 33 5.0 .957 
__________________________________________________________________________ 
CPVC (BF Goodrich Co.) 
Wt. % Cl 
I.V. 
Sp. Gr 
__________________________________________________________________________ 
603 .times. 560 (Geon Hi Temp) 
67 0.9 
1.56 
607 .times. 571 (Geon Hi Temp) 
67 0.6 
1.58 
__________________________________________________________________________ 
PVC (BF Goodrich Co.) 
I.V. 
Sp. Gr 
__________________________________________________________________________ 
110 .times. 343 (Geon) 
1.02 
1.4 
110 .times. 334 (Geon) 
0.68 
1.4 
__________________________________________________________________________ 
Lubricants 
Diamond Shamrock 
Chlorowax 500C - 67 wt. % Cl, liquid 
Chlorowax 70S - 67 wt. % Cl, solid 
Rohm and Haas 
Paraplex G62 
(epoxidized soybean oil), sp. gr. = 
0.993, freeze pt. = 
41.degree. F., flash point = 600.degree. F. 
Technical Processing, Inc., Paterson, New Jersey 
TE - 80 
Stabilizers 
M&T Chemicals 
Thermolite T-66 (liquid organo-tin-sulfur) 
Cincinnati Milicron 
Avastab 180 (liquid organo-tin-sulfur) 
__________________________________________________________________________ 
.sup.(a) Data from Dow's Literature 
TABLE I 
__________________________________________________________________________ 
A B C D E F 
SAMPLE DESIGNATION 
(119-7) 
(129-E) 
(129-C) 
(129-A) 
(119-6) 
(119-2) 
__________________________________________________________________________ 
PVC 110 .times. 343 
47 52 52 52 51 46 
EPCAR 807 (EPM) 47 22 22 22 22 
EPCAR 305 (EPM) 19 
CPE 2243-49 13 
-45 25 
EVA, UE 630 25 
UE 607 25 20 13 
STABILIZER (a) (b) (b) (b) (a) (a) 
HDPE, GULF 8412 4 
DUROMETER "A" 90 94 
HARDNESS "D" 35 60 50 55 50 
MELT INDEX 190.degree. C./2160g 
-- .11 .72 -- .06 
R.T. TENSILE, psi 550 2550 1450 2100 (c) 1660 
% ELONGATION 430 110 120 35 110 
AT BREAK 
VISUAL DISPERSION POOR GOOD GOOD GOOD GOOD GOOD 
GARDNER IMT AT - 20.degree. F. 
52 88 
In-lb/75 mil 
__________________________________________________________________________ 
(a) 4% basic lead carbonate, 1.5% Paraplex G62, 0.5% lead stearate 
(b) 1% Avastab 180 
(c) Sample was cheesey no strength 
SUMMARY OF RESULTS OF TABLE I 
Blend A, having no compatibilizing agent, demonstrates the inferior 
properties of a simple 2-component blend of PVC and EPM. Blend E 
demonstrates the inferior properties of a blend containing a completely 
amorphous, low molecular weight, EPM. The other blends of Table I 
demonstrate substantial improvement in both strength and homogeneity 
imparted by the compatibilizing agent. 
TABLE II 
__________________________________________________________________________ 
G H I J K 
SAMPLE DESIGNATION 
(63-D) 
(63-F) 
(63-H) 
(111-2) 
(111-3) 
__________________________________________________________________________ 
CPVC 603 .times. 560 
45 45 45 
607 .times. 571 36 36 
EPCAR 847 (EPDM) 
55 28 28 
807 (EPM) 25 25 
CPE 3623 27 
2243-49 27 35 25 
EVA 
UE 636 10 
STABILIZER (T-66) 
0 .5 .5 2 2 
LUBRICANT (TE-80) 2 2 
DUROMETER "A" 80 92 92 91 93 
DUROMETER "D" 38 50 54 51 46 
MELT INDEX 190.degree. C. 
1.8.sup.(a) 
1.8.sup.(a) 
1.5.sup.(a) 
0.01.sup.(c) 
0.09.sup.(c) 
R.T. TENSILE, psi 
970 1870 2250 2110 1520 
% ELONGATION AT BREAK 
90 110 100 160 110 
__________________________________________________________________________ 
.sup.(a) 21680 gms 
.sup.(c) 2160 gms 
SUMMARY OF RESULTS OF TABLE II 
Blend G, having no compatibilizing agent, demonstrates the inferior 
properties of a simple 2-component blend of CPVC and EPDM. The other 
blends shown in Table II demonstrate greatly improved strength and 
homogeneity imparted by the compatibilizing agent. Blend K demonstrates 
that EVA can improve the melt flow rate of the blend, however, only at 
some sacrifice in the strength of the product. 
TABLE III 
__________________________________________________________________________ 
L M N O 
SAMPLE DESIGNATION 
(112-A) 
(112-B) 
(138-D) 
(138-A) 
__________________________________________________________________________ 
CPVC 607 .times. 571 45 
PVC 110 .times. 334 
55 42 
EPCAR 807 (EPM) 24 32 
HYCAR NITRILE RUBBER 
45 
(33% Acrylonitrile) 
CPE 2243-45 7 11 
CPE 2552 7 11 
CHLOROWAX 70S 5 
DOP 32 
EVA 607 5 9 
CaCO.sub.3 23 
TiO.sub.2 + Lubricant 5 4 
AVASTAB 180 1 2 1 
DUROMETER "A" 72 
DUROMETER "D" (@ RT.) 
60 60 41 
TENSILE 1700 1550 2075 1150 
% ELONGATION AT BREAK 
400 310 65 170 
GARDNER IMT 28 108 &gt;160 128 
In-lbs/75 mil (-40.degree. C.) 
(no break) 
__________________________________________________________________________ 
SUMMARY OF RESULTS OF TABLE III 
Because the glass transition temperature of EP(D)M rubber is less than 
-40.degree. C., this component of the blend greatly improves the impact 
resistance of the compositions of this invention at low temperature. 
Nitrile-butadiene rubbers (NBR) are often blended with PVC because of 
their good compatibility. However, the impact resistance of these blends 
at -40.degree. C. is inferior as shown by Blend L. Low molecular weight 
organic esters, such as dioctyl phthalate (DOP), are often blended with 
PVC in order to soften and impart flexibility to the PVC. DOP imparts fair 
impact resistance at -40.degree. C. (if enough is added to the blend); 
however, DOP is a volatile plasticizer. Thus, exposure of the sample to 
elevated temperatures or contact thereof with soapy water will result in 
removal of this plasticizer from the blend either because of evaoporation 
or by virtue of it being extracted by the solvent. The blends of the 
present invention have superior impact resistance at -40.degree. C. and 
are resistant to extraction by solvents and stable at relatively high 
temperatures. 
TABLE IV 
__________________________________________________________________________ 
OXYGEN INDEX AND NBS SMOKE CHAMBER STUDIES 
P Q R S T U 
SAMPLE DESIGNATION 
(73-J) 
(73-K) 
(95-SX) 
(154-EW) 
(159-D) 
(159-E) 
__________________________________________________________________________ 
POLYPROPYLENE 20 
CPVC 603 .times. 560 
53 51 17 
PVC 110 .times. 334 39 25 
EPCAR 807 (EPM) 
30 29 26 
EPCAR 847 (EPDM) 34 22 22 
CPE 2243-45 15 48 48 
CPE 2243-49 17 17 20 
EVA 607 -- -- -- 7 -- ---CHLOROWAX 500 -- -- 24 
-- -- -- 
CALCIUM STEARATE 
-- -- -- 1 .5 .5 
TALC -- -- 7 -- -- 5 
AVASTAB 180 0.5 0.5 1 2 2 1.5 
Sb.sub.2 O.sub.3 
-- 3 3 2 2.5 3.0 
DUROMETER "A" 88 88 
DUROMETER "D" 55 55 37 50 
OXYGEN INDEX 25 31 28 29 31 25 
__________________________________________________________________________ 
SUMMARY OF RESULTS OF TABLE IV 
Oxygen Index (OI), measured as described in ASTM Procedure D-2863, was used 
to compare the relative flammability of several of these blends. The 
higher the OI number, the more difficulty in igniting the sample (e.g. the 
higher the O.sub.2 /(N.sub.2 +O.sub.2) ratio need to sustain burning). 
Halogen containing organic compounds are inherently more flame resistant 
than organic compounds containing only hydrogen and carbon. Blends P and Q 
demonstrate the additional benefits derived by the addition of antimony 
trioxide (a well-known synergist with halogen) in raising the Oxygen 
Index. 
A compound is normally considered quite flame resistant if its Oxygen Index 
is greater than about 28. Blend U demonstrate that even with antimony 
trioxide present, and about half of the weight fraction of the blend being 
chlorinated, the Oxygen Index is unexpectedly below anticipated levels 
when hydrocarbon is substituted for PVC. 
The foregoing Tables I thru IV clearly demonstrate the superiority of the 
blends of the instant invention both with respect to impact resistance at 
low temperature and other desirable, advantageous properties. 
The foregoing examples are intended as simply illustrative of this 
invention and not an attempt at delineation of its scope which is set 
forth in the following claims.