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Патент USA US3088939

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United States ‘Patent
3,088,929
Patented May 7, 1963
2
1
The chlorinated copolymers of the invention are pre
3,088,929
pared :by chlorinating the corresponding unchlorinated
PROCESS OF CURING A CHLORINATED ETHYL
ENE HIGHER ALPHA OLEFIN COPOLYMER
Henry S. Makowski, Carteret, and William P. Cain,
Roselle, N.J., assignors to Esso Research and Engineer
copolymers with a chlorinating agent such as free chlorine
at a temperature in the range of 25 to 150° C. and in an
inert diluent such as carbon tetrachloride, chloroform,
chlorobenzene, benzene, and the like. An advantageous
ing Company, a corporation of Delaware
No Drawing. Filed June 2, 1958, Ser. No. 738,940
process for preparing the chlorinated copolymers of the
invention is described in copending application S/N
4 Claims. (Cl. 260-41)
725,513 ?led April 1, 1958, by W. P. Cain et al. In par
The present invention relates to synthetic rubber and
more particularly to chlorinated rubbery amorphous low 10 ticular, chlorinated copolymers can be prepared accord
ing to the process of this copending application by polym
pressure copolymers which can be cured to produce
erizing ethylene and a higher alpha ole?n in contact with
a synthetic rubber.
a low pressure polymerization catalyst in an inert diluent,
The low pressure polymerization and copolymerization
preferably inactivating or removing the catalyst, and then
of alpha ole?ns with catalyst systems made up of a par
tially reduced heavy transition metal halide and a re
15 treating the reaction mixture with a chlorinating agent at
a temperature in the range of 40 to 150° C., preferably
70° to 120° C. The resulting chlorinated copolymer is
then isolated from the chlorination reaction mixture.
ducing metal-containing compound to high density, high
molecular weight, solid, relatively linear products is now
well-known, see e.g. Belgian Patent 533,362, “Chemical
and Engineering News,” April 8, 1957, pages 12 through
16, and “Petroleum Re?ner,” December 1956, pages 191
It is to be noted that when parts or percentages are
20 given in the speci?cation and claims the parts or per
centages are based on the weight of chlorinated co
I through 196.
polymer, unless otherwise noted.
The preparation of synthetic rubber by curing chloro
It has now been found that the chlorinated copolymers
sulfonated polyethylene is also known to the art. How
of the invention can be cured with a combination of
ever, chlor'osulfonated polyethylene is completely satur
curing ‘agents to excellent synthetic rubbers. In particu
ated and contains both ——SO2Cl and -~Cl groups attached 25 lar, since they contain both unsaturation and relatively
to the hydrocarbon chains. Curing is eifected through
active chlorine groups, a combination of (1) a curing
the -—SO2Cl groups alone since most of the -—Cl groups
agent which cures through chlorine groups and (2) a
are secondary halogen groups and thus have a low order
curing agent which cures through unsaturation is used.
of reactivity. Additionally, since the curing takes place
dicumyl peroxide alone can be used. Also,
through intermediate —SO3H groups by hydrolysis of 30 Alternatively,
combinations of dicumyl peroxide with either a curing
the -SO2Cl groups, an acid such as abietic acid is a
agent which cures through chlorine groups or a curing
necessary part of the curing mixture. Chlorinated poly
agent which cures through unsaturation, or both can be
ethylene is also known but contains few double bonds
used. For example, dicumyl peroxide plus sulfur or
and has such a low order of reactivity for the chlorine
oxide or both can be used. From 0.5 to 15, pref
atoms contained therein that their curing is quite di?icult. 35 zinc
erably from 2 to 8 parts of the chlorine group curing
No synthetic rubbers made by curing chlorinated poly
agent is used per 100 parts of chlorinated copolymer and
ethylene is known to the art. However, chlorinated poly
from 0.5 to 10 parts, preferably from 1 to 7 parts of the
ethylene Which is also unsaturated is known to the art,
unsaturation curing agent is used per 100 parts of chlori
but this material is not rubbery, and while it can be cured,
40 nated copolymer except when dimethylol phenol resins
the products obtained are in the range of flexible leathery
‘are used as the unsaturation curing agents. When these
materials to hard plastics Additionally, certain chlori
resins are used, they are used in the proportion of from
nated and chlorosulfonated polypropylenes are known to
5 to 15 parts per 100 parts of chlorinated copolymer.
the art, but synthetic rubbers have not been successfully
Curing agents ‘adapted to cure through chlorine groups
prepared therefrom.
It has now been found that chlorinated rubbery amor
45
phous copolymers of ethylene and a higher alpha ole?n
include metal oxides, metal salts, metal powders, amines
and polyamines. In general, the metal components of the
metal salts, metal oxides and metal powders are chosen
from groups HA and IIB of the ‘Periodic Table ‘and cop
ing very good ozone resistance, mechanical properties,
per, and iron. Particularly useful are the metal oxides,
and resiliency.~
50 sul?des, nitrates, phosphates, sulfates, and organic acid
can be cured to produce excellent synthetic rubbers hav
The chlorinated copolymers of the invention are co
salts of zinc, cadmium, manganese, iron and the lead.
polymers having an ole?n content of 15 to 85 mol percent
When amines and polyamines are used in the curing mix
ethylene and 85 to 15 mol percent of a higher alpha ole?n
ture, they are chosen from any diamine, triamine and
containing from 3 to 8 carbon atoms such as propylene,
higher polyamine having one or more of the following
butene-l, heptene-l, and the like which contain from 1 55 types of amino groups; (a) unsubstituted amino groups,
to 30 wt. percent, preferably 2 to 15 wt. percent chlorine
(b) monosubstituted amino groups, (0) disubstituted
according to the Dietert Halogen Determination; have a
amino groups, and (d) heterocyclic amines such as pyri
crystallinity of less than 25%, usually less than 10% as
dine. The substituents on the mono- and di-substituted
determined by X-ray diffraction at room temperature;
amino groups are one or more alkyl, aryl and heterocyclic
have softening points of less than 25° C. as determined 60 groups.
on the Nalge melting point apparatus; tensile strengths
The components of the curing mixture useful for cur
determined by ASTM-D-412 of from 50 tov 1000 p.s.i.,
ing through unsaturation include sulfur, resins such as
dimethylol phenol resins and halogenated dimethylol
preferably 50 to 500 p.s.i.; an apparent modulus of elas
ticity at —50° C. (ASTM-D-1043) of from ‘10,000 to
phenol resins, and quinone dioxime and its derivatives.
400,000 p.s.i., preferably from 50,000 to 200,000 p.s.i.,
65 Either the chlorine group curing agent or the unsaturation
and more preferably from 60,000 to 150,000 p.s.i.; and
curing agent can be used alone to effect partial curing,
and this is within the broader scope of the invention, but
the use of either type of curing agent is not to be consid
intrinsic viscosities in tetralin at 125° C. at a concentra
tion ‘of one gram per liter of from 0.4 to 3.5, preferably
0.9 to 2.5. The chlorinated copolymers also contain un
saturation as evidenced by iodine numbers of up to 30, 70
infra-red spectra, and the‘ fact that partial curing can be
elfected with the use of sulfur as the curing agent.
ered as equivalent to the use of a combination of these
curing agents since in general much poorer properties are
obtained for the synthetic rubbers when only one type of
curing agent is used.
3
4
When dicumyl peroxide is used as the curing agent,
from 0.1 to 10 parts by Weight, preferably 0.5 to 4.0 parts
tion. This chlorinated copolymer blend was then cured
as shown in Table II using the following curing recipes.
by weight per 100 ‘ part of chlorinated coplymer is
Parts by weight
(A) Chlorinated ethylene-propylene copolymer____ 100
employed.
Fillers such as carbon blacks, silica, mica ‘and others of
Semi-reinforcing furnace ‘black __-__'_______ __
like nature can be added to the curing mixtures in amounts
50
(B) Chlorinated ethylene-propylene copolymer"..- 100
of from 5 ‘to 150 parts, preferably about 50 parts. Any
Semi-reinforcing furnace black ___________ .. 50
type of carbon black can be used, such as channel blacks,
Zinc oxide
5
furnace blacks, acetylene blacks, lamp blacks, and the like.
(C)
‘Chlorinated
ethylene-propylene
copolymer..___
100
However, when dicumyl peroxide is used as a curing 10
Semi-reinforcing furnace black ___________ __ 50
agent a neutral or ‘basic carbon black is required such as
Sulfur ________________________________ __
2
the furnace blacks.
Tetramethylthiuram disul?de ____________ __
1
A small quantity, i.e. from 0.01 to 8%, preferably
Benzothiazyl disul?de __________________ __
from 0.5 to 3% of a conventional rubber accelerator, for
example tet'rame'thylthiu'ram disul?de, benzothiazyl disul
?de, 2-mercaptobenzothiazole, N-cyclohexylbenzothia
1
(D) Chlorinated ethylene-propylene copolymer____ 100
15
zble-Z-sulfenamide, selenium diethyl dithiocarbamate di
sul?de, and zinc butylxanthate can also be added with the
?ller. Mixtures of rubber accelerators can also be used.
Additionally, antioxidants can be added when desired,
Semi-reinforcing furnace black _________ _..__.
50
Zinc oxide ____________________________ __
5
Sulfur
2
Tetramethylthiuram disul?de ____________ __
Benzottn'azyl disul?de ___________________ __
1
1
such as for example secondary aromatic amines and
EXAMPLE II
phenols, e.g., phenyl-beta-naphthylamine, N,N’-di-beta~
A chlorinated ethylene-propylene copolymer was pre
pared according to the process’of Example I and the de
tails of preparation are ‘given in Table ‘I. This chlori
naphthyl - p ~ phenylene .- diamines, aldol-alpha-naphthyl
amine, 2,2,4 - trimethyl-1,2 - dihydroquinoline, hydroqui
none monobenzyl ether, and 2,2'-methylene-bis>(4-methyl
6-tert.butylphenol). From 0.01 to 10%, preferably 0.1
25 nated ethylene-propylene copolymer was then cured ac
cording to recipe D above which includes both sulfur
to 2% of antioxidant can be used. When quinone di
and zinc oxide with the results‘shown in Table II. Addi
oxime or its derivatives are used, it is advantageous to in
tionally, a sample of the unchlorinated copolymer was
clude from 5 to 15 parts by weight of an oxidizing agent
also cured with mixture D for comparison purposes. ‘It
such as red lead in the curing mixture rather than an 30 can be seen from Table II that the unchlorinated ethylene
‘antioxidant. It should be noted that all antioxidants can
propylene copolymer cannot successfully be cured with
a sulfur-zinc oxide recipe.
not be used with dicumyl peroxide. However, certain
antioxidants such as hydroquinone monobenzyl ether that
EXAMPLE HI
do not react rapidly with dicumyl peroxide at curing tem
A-sample of the chlorinated copolymer of Example 11
peratures can be employed.
35 was mixed with dicumyl peroxide according'to the follow
Oils derived from coal tar, pine tar and/or petroleum
ing recipe:
can be added to the curing mixture if desired and from
Parts of weight
2 to 30'parts, preferably 5 to 15 parts by weight of oil
Chlorinated ethylene-propylene copolymer _______ __ 100
per 100 parts of chlorinated polymer can be employed
to serve as inexpensive ?llers, softening agents or tackify 40 Semi-reinforcing carbon black _________________ .._ 50
ing agents.
Dicumyl peroxide (40% on CaCO3) ___________ .._
ing the resulting mixture in a standard rubber press in the
‘range‘of from 225° F. to 350° F., preferably 280° F. to 45
315° F. and more preferably about 310° F. until curing
"is effected. Fillers, rubber accelerators and antioxidants
are added with the vcuring agent mixture as desired. The
mixing is carried out in a rubber mill followed by heating 50
the resulting mixture to reaction temperature in a stand
ard rubber press ‘or other conventional ‘rubber curing
equipment. The ‘mixing can also be carried out in other
- The cured chlorinated copolymers of the invention
Ex. I.
55
have excellent mechanical properties, dynamic proper
ties, and ozone resistance. They are useful wherever a
good general purpose elastomer is required, such as ‘in
tires, hoses, gaskets and the like. Their use in tires is
particularly advantageous since the synthetic rubber of
the invention is tough and yet resilient and ozone resistant.
The invention will be understood more clearly from
the following examples.
EXAMPLE I
A chlorinated amorphous ethylene-propylene copoly
mer was prepared ‘by chlorinating a blend of several
ethylene-propylene copolymers each of which was pre
pared by polymerizing an ethylene-propylene ‘feed with
an AlEt3-TiCl4 catalyst in n-heptane diluent. The chlori 70
nation was carried out with chlorine gas and a benzene
Ex. II
Unchlorinated polymer _________ ._ Ethylene~propylene copolymer
Polymerization‘ catalyst .... ._
Polymerization diluent ____ .-
Mole ratio of ethylene to pro
Ethylene-propyl
one copolymer
AlEti/TiCli ____ _.
n=heptane ____ ...
AlEts/TiCh.
n=heptane_..-.
1. 66 ____________ __
82, 000 __________ _.
2. 32.
140, 000.
pylene in feed.
1/1.
Inherent viscosity, 'qil ______ _‘Molecular weight2 __________ __
Iodine number, cg. of Iz/g.
of polymer.
Number of double bonds per
' rubber compounding equipment, such as Banbury mixers
and kneaders.
4
The results obtained are shown in Table ‘II.
Table I
The reaction between the chlorinated copolymer and
the curing agent is carried out ‘by mixing the chlorinated
copolymer and the curing agent in a rubber mill and heat
carbon atorns.a
Gel, percent ________________ -.
Reaction:
1. 60 ____________ ..
0.06 ____________ ._
33. 5 ____________ _.
42.1.
'
'
Benzene.
Approx. 011 teed, coJmin- __
900.
65.
310.
Temperature, °l0 .......... ._
ime, minutes ...... __
70.
15.4
Polymer, g_._
Produ
Insolublep'olymer, g. _
64.
Soluble ‘oily polymer, g
Total product, g __________
11.
-_
75.
Properties of insoluble product:
Inherent viscosity, 1111 ______ -.
1.24 ____________ __
vMolecular Weight2 __________ __
50,400 __________ __
79, 000
Gel, percent
27.6
48. 3.
1. 64.5
Chlorine, weight percent"... 6.7 _____________ __ 4.1
Iodine number, cg. of Ii/g. of
polymer.
8 _______________ __
3.1
100 carbon atoms3 ........ __
0.3 _____________ __
0.1
Number of double bonds per
1 In tetralin at 125° C. at a cone. of lg./l.
2 1. Harris correlation for polyethylene, J. P01. 801., 8, 361 (1952).
3 In the determination of the amount of unsaturation from the iodine
number, it was assumed that 3 iodine atoms react for every double bond
diluent in the presence of ultra violet light. The proper
present in the polymer.
ties of the chlorinated ethylene—propylene copolymer
4 Ch gas was ?rst passedinto the reaction at the rate of 310 ccJml. for
20-25 minutes at reaction temperature in the absence of U.V. light-to
blend are given in Table I With the details of prepara 75
saturate the solution with Oh.
_
.
l Incompletcly soluble in tetralin at 125° C. at a concentration of 1g./l.
3,088,929
Table II
lowing recipe:
Tensile Elonga
strength,
tion
Conditions
Exam lo I:
AP. ___________________________ _.
B _____________________________ __
C _____________________________ ._
p.s.i.
5’/308° F__
15’/308° F"
360
420
407308" ._
5’/308° F
830
870
15’/30S° F__
1, 990
40’/308°
__
2,090
60’/308° F__
2,170
percent
720
540
510
280
600
820
607308“ F__
1,810
480
5’/308° F _
15’/30S° I“__
407308" IL?0’/308° F__
2,000
560
D (unchlorinated copolymer).-. 30’/309°
F__
60’/309° F._
90’/300° 11,
(1)520
(1)
(X) 330
(1)
D (chlorinated copolymer) ____ __
2, 340
440
120’/309° I<‘__
Example III ______________________ __
35’/309° F._
(SW/300° I"__
90/309" F"
120’/309° F__
30’/310°
__
(SW/310° F__
90’/3l0° F"
120'/310° I*‘__
Zinc oxide _____ __
5
Stearic acid ________________________________ __
Sulfur _--..Tetramethylthiuram disul?de __________________ __
Benzothiazyl disul?de ________________________ __
1
2
1
1
x
540
400 10 Semi-reinforcing furnace black ________________ _..
290
where x is either 25, 50, 75 or 100 parts of semi-reinforc
280
15’/308° F._
Example II:
Parts by weight
Chlorinated ethylene-propylene copolymer _______ __ 100
__
D ____________________________ __
5’/308°
6
was divided into portions and cured according to the fol
ing furnace black. These mixtures were cured at 308° F.
780
for 45 minutes. Tensile strengths of from 2510 to 2980
were obtained with elongations of from 180 to 540%. A
400
300 15 curing mixture was also prepared according to the above
280
recipe except in the absence of any carbon black. This
2.080
2,650
2,660
510
mixture was also cured at 308°- F. for 45 minutes. The
tensile strength of this synthetic rubber was 1070 psi with
an elongation of 470%. It can be seen from this example
that different quantities of ?llers such as carbon black
350
2, 350
2,220
2,340
380
360
370
2,360
are effective for improving the properties of the synthetic
rubbers of the invention.
EXAMPLE VI
290
2,080
2,590
2, 480
250
290
80
25
Samples of natural rubber, GR-S 1500, butyl 217, and
a chlorinated ethylene-propylene copolymer prepared
from a 510-50 volume percent ethylene-propylene feed
and chlorinated to a chlorine content of 4.8% were cured
1 Did not cure.
It can be seen from Table II that the cured chlorinated
according to the following recipes with the curing condi
copolymers of the invention have good tensile strength
and elongation properties. Also, the advantages of using 30 tions and mixtures most suitable for each.
Parts by weight
curing mixture D which contains both sulfur and zinc
oxide are apparent when compared with curing mixtures
B and C in Table II which contain zinc oxide only and sul
fur only respectively. Moreover, the effectiveness of cur
(F) Natural rubber _______________________ __ 100
Semi-reinforcing furnace black __________ __ 50
ing with small quantities of dicumyl peroxide is apparent
from the results obtained in Example III.
35
In addition to the above properties, the relative damping
of the cured copolymers was measured on a Yerzley oscil
lograph and found to be in the range of 18 to 24%. This
range is as good as is obtained with GR-S and is consid
EXAMPLE IV
A chlorinated rubbery amorphous ethylene-propylene
copolymer which contained 4.0‘ wt. percent chlorine was 45
prepared by chlorinating an ethylene-propylene copolymer
polymerized from a 50-5 0 volume percent ethylene-propyl
ene feed in n-heptane using an AlEtg/TiCli catalyst. This
chlorinated copolymer was divided into portions and
Parts by weight
Zinc oxide _________________________________ __
5
Sulfur
2
_
__.__
Tetramethylthiuram disul?de __________________ _..
Benzothiazyl disul?de ________________________ __
______________ __
1
Phenyl betanaphthylamine _____________ __
1
Zinc oxide __________________________ __
5
Sulfur ______________________________ __
2
Stearic acid _________________________ _.
Benzothiazyl disul?de _________________ __
2
1.5
Phenyl betanaphthylamine _____________ __
Copper dimethyl dithiocarbamate _______ __
1
0.1
50
Zinc oxide __________________________ .__
5
Sulfur _______________________________ __
2
Tetramethylthiuram disul?de ___________ __
Benzothiazyl disul?de ________________ __'__
1
1
(I) Chlorinated ethylene-propylene copolymer; 1‘00
Chlorinated ethylene-propylene copolymer _______ __ 100‘
50
1
Z-mercaptobenzothiazole
Semi-reinforcing furnace black __________ __
ing to the following curing receipt.
___
3
Stearic acid _________________________ __
(H) Butyl rubber 217 ____________________ __ 100
each portion mixed with a different carbon black accord 50
____
5
______________________________ __
(G) GR-S 1500 _________________________ __ 100
Semi-reinforcing furnace black __________ __ 50‘
erably better than that ‘obtained with butyl rubber.
Carbon black
Zinc oxide __________________________ __
Sulfur
Semi-reinforcing furnace black _________ __
55
1
1
50
Zinc oxide __________________________ __
5
Sulfur ______________________________ __
‘2
Tetramethylthiuram disul?de ___________ _..
Benzothiazyl disul?de _________________ __
1
1
The above curing mixtures were cured at the times
The following carbon blacks were used: Super abrasion 60 and temperatures shown in Table III and thereafter were
furnace, high abrasion ‘furnace, fast extruding furnace,
semi-reinforcing furnace, medium thermal, and ?ne ther
mal. These curing mixtures were cured at 310° F. for
30 minutes. The tensile strengths of the synthetic rubbers
produced varied from 1640 psi. to 2930 psi. with elon 65
stretched to 50% extension and subjected to a concen
tration of 0.2% ozone. The time for each synthetic
rubber to break was recorded and is given in Table III.
Table III
gations of from 325 to 525% . It can be seen from this ex
ample that a large variety of carbon blacks can be em
ployed.
_
EXAMPLE V
70
F (natural rubber)
A chlorinated ethylene-propylene copolymer which con
G (GR~S 1500)
II (butyl rubber 217)
tained 5.9 wt. percent chlorine and which was prepared by
chlorinating an ethylene-propylene copolymer polymerized
from a 50—50 volume percent ethylene-propylene feed in
chlorobenzene using an AlEt3/TiCl3-O.2A1Cl3 catalyst
_
Curing mixture
I (chlorinated ethylene-propylene copolymer)
Curing
Time to
conditions
break,
20'/287° F.”
30’I287° F.-.
4073080 F...
40’/308° F_._
min.
6
6
225
870
It can be seen from Table III that the cured chlorinated
3,088,929
3
ethyleneepropylene :copolymer of the invention exhibits
It can be seen from the above table that the cured
a markedly greater ozone resistance than the other rub
chlorinated copolymer of the invention has much better
resilience than butyl rubber below 75° C.
The above examples are given for illustration purposes
bers ‘employed in the test.
EXAMPLE ‘VII
The chlorinated ethylene-propylene copolymer of Ex
only and are not intended to limit the invention. Varia
tions in the invention can be made without departing
from the scope and spirit of the invention.
iample 51V was cured _for '30 minutes at 308° F. according
to the following curing recipe:
What is claimed is:
Parts by weight
Chlorinated ethylene-propylene copolymer _____ __ 100 10
Semi-‘reinforcing carbon black ________________ __
50
prising the steps of:
(ll) mixing (a) a chlorinated copolymer having an
_>________ __Y____-_ ________________ __
5
ole?n content consisting essentially of 15 to 85 mol
____ _‘_ ______________________________ __
2
percent ethylene and 85 to 15 mol percent of an or
Zinc oxide
Sulfur
'
1. The process for forming a synthetic rubber com
Tetramethylthiuram disul?de _________________ __
1
ole?n containing from 3 to 8 carbon atoms, and
Benzothiazyl disul?de __~____~_ ________________ __
1
having a chlorine content of from 1 to 30 weight per
Stearic acid ____I_ __________________________ __
1
cent, said copolymer having been chlorinated at a
temperature of 70°—1210° C.; and (b) a curing agent
selected from the class consisting of dicumyl per
oxide; metal oxides, metal salts and metal powders,
Samples of butyl rubber Y217 and natural rubber were
cu'redacco'rding to the following recipes:
7
Parts by weight
the metal components of which are groups IIA and
vButyl rubber 217 _________________________ __ 100
Medium processing channel black ___________ __ ‘50
Zinc oxide _______________________________ __
5
Sulfur ___, ________________________________ __
2
Tetramethylthiuram disul?de _______________ __
Benzothiazyl disul?de _____________________ __
1
'1
Stearic acid _________ l. ___________________ __
0.5
HE metals, copper and iron; heterocyclic amines;
sulfur; quinone dioxime and its derivatives; mix
tures thereof; and
(2) heating the resulting mixture to curing tempera
25
additionally includes tetramethylthiuram disul?de and
‘benzothiazyl disul?de as accelerators.
3. The process of claim 2 wherein the curing mixture
Natural rubber ___________________________ __ 100
Medium processing channel black ____________ __
50
Zinc oxide _______________________________ __
3
Sulfur ___________________________________ __
2-mercaptobenzothiazole ___________________ __
3
1
Reogen
_________________________________ __
2
Stearic ‘acid _____________________________ __
3
30
Theresilience was measured on the ‘Good
year-Healy _Rebound instrument ‘according to ASTM
D1054-55.
40
Table I V
Chlorinated
Butyl
copolymer
Natural
rubber
Curingconditionsnn 30' at 308° F-.- 50’ at 307° F___
Rebound, percent:
23° C7
45
»
'54.
26° C
35° C
43° C
_
29
74° C
99° C
100° C
64.
___
56
50° C
70° C
_
36
___.
55’ at 274° F.
57.
>
46
___.
56
____ __
71.
__ .58
"61
64
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,200,429‘
2,405,971
2,691,647
2,850,490
2,920,064
2,958,672
rubber
76.
Perrin et a1 ___________ __ May .14,
McAlevy _____________ ___ Aug. 20,
Field et al. ___________ __ Oct. 12,
Canterino et al. _______ __ Sept. 2,
Baptist et al. __________ __ Jan. 5,
Goldberg _____________ ___ Nov. 1,
1940
1946
1954
.1958
1960
1960
FOREIGN PATENTS
45
0° C
comprises zinc oxide, sulfur, tetramethylthiuram disul
?de and benzothiazyl disul?de.
4. The process of claim 3 wherein the curing mixture
additionally includes carbon black.
The curing conditions and the resilience of the above 35
cured rubbers at different temperatures are given in
Table IV.
tures to cure said chlorinated copolymer.
2. The process of claim 1 wherein the curing mixture
478,513
Canada _____________ __ Nov. 13, 1951
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