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Патент USA US3060999

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1
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3,669,939
,
BLENDS OF CliS-POLYBUTADENE WITH EITHER
NATURAL RUBBER 0R CI§-PQLYIS®PRENE,
METHOD OF PREPARING SAME, AND TIRE
TREAD COMPRISHNG SAME
Henry E. Raiisbaek and Nelson A. Stumpe, In, Barties
rubber, or blends of previously known syntheticfrubbers
with natural rubber, results in premature failure on ac‘
count of heat blowouts, particularly in heavy. duty tires.
This problem is ‘so acute that practically all large’ truck
ville, Okla, assignors to Phillips Petroleum Company,
a corporation of Delaware
2
(styrene/butadiene . copolyrner rubber) for‘; example,
show superior tread wear, natural rubber is ‘superior in
hysteresis properties. The poorer hysteresis of synthetic
,
tires are made using natural rubber. The ‘supply of
natural rubber has been short in the past several years,
10 and with the production of automobile and truck tires
This invention relates to blends of cis-polybutadiene
being increased every year, it is easily foreseen that the
with natural rubber and with cis-polyisoprene.
supply of natural ‘rubber will become even shorter.
No Drawing. Filed Aug. 17, 1959, Ser. No. 833,975
10 Claims. (Cl. 152—33ti)
This is a continuation-impart of our copending appli
cation Serial No. 751,150, ?led July 28, 1958, now
, ‘It is known in the ‘art thatbutadiene can be polymer
abandoned, for Blends of Cis-Polybutadiene with Natural 15
Rubber. Application Serial Number 751,150 was a con
utility in many applications, the higher Mooney poly
tinuation-impart of our application Serial Number 699,
187 (now abandoned), ?led on November 27, 1957.
butadi'enes (ML-4 at 212°, F.7of
Various methods are described in the literature for
polymerizing 1,3-butadiene, including emulsion polymeri
zation, alkali metal-catalyzed polymerization, and al?n
catalyzed polymerization. Emulsion ‘polymerization of
1,3'-butad_iene gives a polymer with from about 60 to
ized to polymers consisting primarily of cis'—1‘,4-'co'n?gura
tion. However, while the polybutadienes containing sub—
stantial amounts of _cis 1,4-con?guration have excellent
20
and -above)._have
exhibitedpoporer processing characteristics than SBRor
natural rubber, e.g., are more di?icult to mill, These
cis-polybutadienes have excellent hysteresis ‘properties,
but it would be desirable if thetensile strength of these
polymers could be increased signi?cantly.
_,
_
about 80 percent trans ‘IA-addition, from about 5 to
It has now been found that blends ofthe'se cis-poly
about 20 percent cis 1,4-addition, and from about 15 to 25 b'utadi'enes with natural rubber and with- cis-polyisjopren'e
about 20 percent 1,2-addition. Sodium-catalyzed poly
have good hysteresis properties, low heat build-up’, good
butadiene has from about 60 to about 75 percent 1,2
?ex life,.and.good tensile strength;
addition, the remainder being cis and trans 1,4-addition.
. _It is therefore an object of this invention’ to provide
1
_
When potassum and other alkali metals are employed as
blends of cis-polybutadiene with natural rubber and with
catalyst, the latter ratios may vary to some degree, but 30 cis-polyisoprene which ‘can be utilized in the applications
no polybutadiene prepared in presence of the alkali cat
for _which natural rubber alone is used at the present
alyst containing more than about 35 percent of cis 1,4
con?guration has been obtained. Al?n-catalyzed poly
time.
.
.
_ ‘it is another object of thisinvention to provide blends
butadiene has from about 65 to about 75 percent trans
of cisipolybutadien'e with natural rubber andwith cis
1,4-addition, from about 5 to about 10 percent cis 1,44 35 pol‘yiso'pi'ene, which exhibit good hysteresis properties,
addition, and from about 20 to about 25 percent 1,2
good tensile strength, good ?ex ‘life and low heat build-up,
a'cldition. For a more complete discussion of the con
It‘is another object of this invention to provide a means
?guration of p'olybutadiene, reference is made to an arti
of extending natural rubber without sacri?cing its ‘desira
cle by J. L. Binder appearing in Industrial and Engineer
ble properties for tires, especially‘ heavy dutytypes. ,
40
ing Chemistry No. 46, 1927 (August 1954).
Natural rubber has long been a commodity of com;
merce, and the art is well aware of such natural rubbers.
It is still another object‘ of this invention to? provide"
blends containing cis-polybutadiene, which have‘ good‘
processing
properties.
‘
_
I
H
I
p
>_
The most widely used rubber latex is that gathered from
Still ‘other objects, advantages and features of, this “in-‘i
the tree Hevea brasiliensis. It is generally accepted to
45 vention will be apparent .to those skilled in the art upon
day that natural rubber is substantially a cis-polymer of
consideration of this disclosure.
isoprene (2-methyl-1,3-butadiene). It is also known to
_The above and other objects of
invention are’ ac
the art that natural rubber ?uctuates widely in price, but
complished by preparing a blend of rubber containing 10’
hasrgenerally been more expensive than the synthetic
to‘ parts ‘per ,1 ()0 parts by, weight rubber of a synthetic
rubbers, especially since World War II when the produc 50 polybutadiene containing at least 75 percent butadiene
tion of various synthetic rubbers has increased many fold.
joined together by cis’ “1,4 linkage, the remainder being‘
_ Various synthetic rubbers and natural rubbers have
chie?y a cis-_p'olyisoprene, i.e,,, natural rubber or a syn-1
been blended with each other and with ?llers for various
thetic cis-polyisoprene containingv at‘ least 75 percent
purposes. However, when synthetic rubber and natural
isoprene joined together by cis 1,4-linkage'. __Of_ course,
rubber are blended, the properties of the blend general 55 additives such as carbon black, antioxidants,“softeners
ly trend toward the poorer of the two components. This
and other additives} and preservatives known in the art
is especially true in respect to heat build-up and ?ex life,
can be present in the blend. _
_
and, consequently, the use of blends of synthetic rubber
The cis~polybutadienes which ‘are utilized in the rub:
with natural rubber in utilities where natural is normal;
ber compositions of this invention can be produced by
ly used alone has not proven satisfactory.
60 any of the known polymerization processes which yield
Although natural rubber has been utilized for a num
predominantly cis-1,4—butadierie' polymers. , The cis
ber of years in a multitude of applications, one of the
polyb'utadiene which can be employed in the nlbberlcomr
largest uses at the present time is in the manufacture of
positions of this invention will have a viscosity between
truck tires. While certain synthetic rubbers, SBR
10 and 130‘ as measured on the Mooney viscosimeter at
3,060,989
212° F. (ML-4). A more desirable range of Mooney
viscosity is from 20 to 60, inclusive. The polybutadiene
as contemplated herein is one in which at least 75 percent
and up to 100 percent, preferably 85 to 98 percent, of
the polymer is formed by cis 1,4-addition of the butadi
4
the temperature at which the polymerization is being car
ried out. However, higher pressures can be employed if
desired, these higher pressures being obtained by some
such suitable method as the pressurization of the reactor
with a gas which is inert with respect to the polymeriza
tion reaction.
As has been indicated, natural rubber is well known to
the art and no further discussion thereof is needed here.
one, the remainder of the polymer being formed by trans
1,4- and 1,2-addition of the butadiene. The amount of
the cis-polybutadiene which is employed in the blends
of this invention, the cis 1,4 content of the polymer, and
The cis-polyisoprenes used in the rubber composition
the Mooney viscosity of the cis-polybutadiene will all
of this invention can be produced by any of the known
depend upon the desired ultimate use of the blend and
polymerization processes which yield a predominantly cis
the physical properties desired for the ultimate use. In
1,4-polymer of isoprene. The cis-polyisoprene is one in
general, the blend will contain at least 10 weight percent
which at least 75 percent and up to 100 percent, preferably
natural rubber or cis-polyisoprene and preferably at least 15 85 to 95 percent, of the polymer is formed by cis 1,4
25 weight percent. A particularly preferred range is 50
addition of the isoprene, the remainder of the polymer
to 60 weight percent natural rubber or cis-polyisoprene
being formed by trans 1,4-, 3,4-, and 1,2-addition of the
and 50 to 40 weight percent of the cis-polybut-adiene.
isoprene. The amount of the polyisoprene formed by
As Has been indicated the cis-polybutadiene useful in
1,2-addition is usually negligible, being in most instances
this invention can be prepared by any method known to
di?icult or impossible to detect by infrared examination.
the art, this invention being in the blended composition.
In one method for preparing cis-polyisoprene, the iso
One means for preparing such polymers is fully described
prene is polymerized in the presence of a catalyst compo
and claimed in the copending application of David R.
sition comprising (a) a trialkylaluminum and (b) tita
Smith, and Robert P. Zelinski ?led April 16, 1956, and 25 nium tetrachloride. The trialkylaluminum can be repre—
having Serial No. 578,166. According to that applica
sented by the formula R3Al, wherein R is an alkyl radical
tion, 1,3-butadiene is polymerized in the presence of a
as described hereinbefore. The polymerization is prefer
catalyst composition comprising (a) a trialk'ylaluminum,
ably carried out in the presence of a hydrocarbon diluent
and (b) titanium tetraiodide. The polybutadiene pro
similar to that mentioned above. The amount of titanium
duced by that method is one in which the rubbery poly 30 tetrachloride used in the catalyst composition is usually
mer is formed by cis 1,4-additi-on, trans 1,4-addition and
in the range of 0.05 to 20 mols per mol of trialkylalumi
‘IQ-addition, at least 85 percent of the polymer being
num. However, a preferred range is from 0.1 to 3.0 mols
formed by cis 1,4-addition.
of the titanium tetrachloride per mol of trialkylaluminum.
The trialkylaluminum in the Smith et al. catalyst can be
The process for preparing the cis-polyisoprene can be
represented by the formula R3Al, wherein R is an alkyl
carried out at any temperature within the range of —100°
radical containing up to and including 6 carbon atoms.
C. to 100° 0., but it is preferred to operate in the range
The alkyl groups can be either straight or branched chain
of —50° C. to 50° C. The polymerization reaction can
be carried out under autogenous pressures. It is usually
The alkyls can 40 desirable to operate at pressures su?icient to maintain the
alkyl, for example, ethyl, propyl, isopropyl, n-butyl, iso
butyl, pentyl, isoheXyl and n-heXyl etc.
be-the. same or different, e.g., diisobutylmonoethylalumi
monomeric material substantially in the liquid phase.
num; however, the preferred catalyst comprises titanium
The amount of the catalyst composition used in the
tetraiodide and triethylaluminum or triisobutylaluminum
since these latter two alkylaluminums have high activity in
polymerization can vary over a wide range.
The concen
tration of the total catalyst composition is usually in the
the process. The amount of trialkylaluminum in the cata 45 range of about 0.01 weight percent to 15.0 weight percent,
lyst composition is usually in the range 1.25 to 50 mols
or higher, based on the amount of isoprene charged to the
polymerization zone. A polyisoprene prepared by this
per mol of titanium tetraiodide with the preferred range
being from 1.5 to 35 mols per mol. When triisobutyl
method is formed by cis 1,4-addition, trans 1,4-addition,
aluminum is utilized, the preferred range is 1.7 to 35 mols
3,4-addition and 1,2-addition, at least 90 percent of the
per mol whereas when triethylaluminum is employed the
polymer usually being formed by cis 1,4-addition.
preferred range is 1.5 to 10 mols per mol. The total
It is to be understood that it is not intended to limit the
amount of catalyst can vary over a wide range. The con
invention to cis-polybutadienes or cis-polyisoprenes which
centration of the total catalyst, titanium tetraiodide plus
have been prepared by any particular method. Thus, the
trialkylaluminum, is usually in the range of about 0.05 55 present invention is applicable to any cis-polybutadienes
weight percent to 10.0 weight percent or higher, prefer
and cis-polyisoprenes having the above-described con?g
ably in the range 0.05 to 5 weight percent, based on the
urations. Another method which can be used to produce
cis-poiybutadienes suitable for use in preparing the blends
total amount of 1,3-butadiene charged to the reaction
zone. In general, at the lower mol ratio of trialkyl
of this invention is described in copending US. patent
aluminum to titanium tetraiodide, it is desirable to oper 60 application Serial No. 722,842, ?led on March 21, 1958,
ate above the minimum level of catalyst concentration.
by F. E. Naylor, now Patent No. 3,004,018. As disclosed
The polymerization of the butadiene can be carried out
in this application in detail, a catalyst comprising a mer
at any temperature in the range of ——40° C. to 150° C.,
cury or zinc-aikyl and titanium tetraiodide is effective in
but it is preferred to operate in the range of —10° to 50°
polymerizing 1,3-butadiene to a cis-polybutadiene. Fur
C. It is also preferred to carry out the polymerization in 65 thermore, other catalyst systems, e.g., those containing
elemental lithium or lithium hydrocarbon, such as alkyl
the presence of an inert hydrocarbon such as aromatics,
straight and branched chain para?ins and cyclopara?ins
lithiums are suitable for use in preparing cis-polyisoprene
by the polymerization of isoprene.
although cyclopara?ins are less desirable than the other
hydrocarbons.
The reaction can be carried out in the 7
absence of any such diluent. The polymerization reaction
can be carried out under autogenous pressure or any suit
able pressure sufficient to maintain the reaction mixture
substantially in the liquid phase. The pressure will thus
The blends of this invention can be prepared in a vari~
ety of ways, but the preferred method for admixing these
cis-polybutadienes with natural rubber or cis-polyisoprene
is with mechanical mixers such as roll mills or Banburys,
either with or without plasticizers, peptizers or other proc
depend upon the particular diluent being employed and 75 essing aids. After admixing the natural rubber or cis
3,060,980
5
6
polyisoprene with the cis-polybutadiene in the desired
ratio, the resulting blend can be compounded and vulcan
spectrometer.
The percent of the total unsaturation present
as trans 1,4- was calculated according to the following equa
tion and consistent units :
ized by well known rubber vulcanization recipes, as for
r
.
example, sulfur plus an accelerator at 307° F. for 30 minutes.
_E
61%
Alternatively, each polymer can be compounded 5
h
‘
t.
\V ere:
m
629x 1H0
Hi _
OD.
CO6
t
(rt
C1811
1 1
i
1)
1 ers-mo S“ -IIl CI'ODS‘
;
separately and the compounded stocks blended to give the
Ezex?nction (10g 10”) ; t=Path length (micronsl; a‘Dd
desired ratio of cis-polybutadiene to natural rubber or
c:ctzintientratign éIi1§1Slg%l15b1e_b0I1d{)1it(i11‘)- d'rtllile exgincgon
'
‘
‘
‘
was
CIS'POIYISOPRPHB _m the ?nal blend- The r_esultmg blenfis’
6 ermine
a
e
.
m-IQTOB
an
an
ever; 1110
OH.
coe?ieient used was 1.21>< 10-2 (1iters-mols—1-microns-1). The
after vulcanization, have excellent physical properties,
good ?ex life, good abrasion resistance, and good resist-
percentlofl the1i total lél‘lsatlil'atti?ln pé'esent as t1,02- (01'iYl11¥l11)
éliter-molsi-micrpni-l)- Thebtperceing 0f iiohte vital glrllsattura
‘
'
'
ca (311 a 8
I!"
0
e a 0V8 e 113-1 11, ‘US 11
and Show Rartlcular
advani‘ages H}
that' low heat bulld‘Elp’
10 was
11.0 micron
band3.000!’
3.116113;
extinction
coef?gieht of 1.52%10-2e
'
'
'
011
:‘mce to agmg (cfaeklPgi ‘etc-)1 A_st1n fflrther advanjxflge
‘S811
{LSCS
,-
0
3.118
S
C111
6133.113
1l,4~ Lgrid 1,2-(v-iInyl) d‘eatirmined acgo'rginga to gthe above
in the
blends
of this
invention
is their processability.
'
_
idnettllilods)
£30mper the
htlbeoretitcal
?hsatulration
zlissitililnin's
v011%
on e
on
eac
1 uni in
e p0 ymer.
n
e case 0
Whlle cls'polybutadlenes havmg ‘a MPOIIeY value_ of 50
Polymer A, the value given is an average value calculated
or above (ML-4 at 212° F.) are dl?'icult to mill, the 15 from the structure of each of the polymers of the blend.
blends of this invention mill well on a roll mill.
Other
Th
blending methods include blending solutions of the two
rubbers and recoverin
g
,1 b, t. d.. .. . .f. .1
bb... b1 . d.
the blend from solution.
. t’,
.
'
..
‘
..
.
,
after milling in the smoked sheet.
EXAMPLES
.
d
by miengiythue iiéelglgl'gllgulgzieli Gil-a 5:11 slgg?rgligatheerep
if.
-.
..
'
The blends were then
2O compounded according to the following recipes, followed
by curing at 307° F. for 30 minutes.
Several runs were made to illustrate the advantage of
It was noticed that
the 60 and 54 Mooney (ML-4)_ elrs-polyblltadlenes
the blends of this invention. These runs are presented to
(Polymers B and C, See Table 1) dld not band at the
illustrate the rubber compositions of this invention but
m111 temperature employed (158 F-),_'b\1t after addlng
.
.
.
.
.
-
'
o
..
'
are not intended to limit the invention to the embodiment 25 ‘the natural rl‘llbbef, the mlxtul'e banded Very ‘Satisfacto
shown therein.
rily at 158° F.
Example I
COMPOUNDING RECIPES
Several runs were made by blending cis-polybutadiene
prepared with triisobutylalurninum and titanium tetra- 30
N 1
iodide catalyst and natural rubber #1 Smoked Sheet
(#1 SS).
The cis-polybutadiene was prepared by the method of
gis_polybutadiene
Smith et al. in toluene diluent utilizing a mol ratio of tri-
I
II
III
.IV
7'
_
'
§§Y§§§BE6JSE§EII13:33:: 1319""
lzijgh abcrlasion furnace black ---- -- 5g
52
28
5g
isobutylaluminum (TIBA) to titanium tetraiodide (TTI) 35
I
of about 5/1. Three different cis-polybutadienes were
used in these blends, these polymers having the following
s
1110
C18 1 ‘AT-Content.
0X1
8 _ . _ _ _ _ . _ _ _ _ _ _ _ _
.
. .
____ __
3
Antioxidant 1 ______ __
3
1
Cis 1,4-add1t1on, percent2 40 Disproportionated rosin__
._
Polymer A 1 —————————————————————————————— —— 81-7
Polymer B ____________________________ __ 89.0
Polymer
1 1 (1 C th
1
.s i
oximatel
e um
V
3
1
1
5
g
3
1.75
n-grgiclghexyl-llbenzothiazole-sulien-
1.0935
or.
"165"
52
. _ . . _..
Steario acid__
,
Smgked
sheet
1 0
3
1
...... _.
1.75
1.75
0 85
0 7
3
1.75
0 4
1Physicalmixture
"""""""""""containing
“ """""""
65%"byweight
'
of a complex
'
'diarylar‘ni'ne
tiongenln 05h‘, g?eepggaivilggl of rfmipgé these pglyrgers 21L) 115/1 45 ketongreaction product and 35% by weight 01 N,N’-diphenyl-p-phen.
mol ratio of triisobutylaluminum to titanium tetraiodide was
ylene lamme'
utilized, whereas a 5/1 mol ratio was utilized in the prepara-
_
tion of the other two.
_
After curing, the physical properties of the blends were
cis2In
Let-addition,
determining
thethe
following
percentage
procedure
of the was
polymer
followed.
formedThe
by
polymers were dissolved in carbon disul?de containing 0.01
>
determlned.
Table I
grain of phenyl-beta-naphthylamine per liter of carbon disul~
50
The results of these tests, are
.
glven
..
1n
‘
_ _
7
_
tidf to forilnf ahsolutlion containing 265 weitght plercetnt 0g thte
From the table, it can be seen that the heat build-up,
5o was
yzner,removed
t e 5yo yiner
reprecipimtmg
as prepare thecon
polymer
aine an
twice
ioxi fyom
an ,
tensile
strength,
g
?ex llf‘e,
etc.,
. of the. blend,
.
especially
.
. the
cyciolgexane prior to preparing the carbon dlsul?de solutwn-
50/50 blends, is essentially as good as that of the smoked
transmission) was then determined in a commercial infrared
5 act alone
The infrared spectrum of each of the solutions
(percent
h
.
.
TABLE I
Polymer A (81.7% 015- Polymer B (89.0% cis- Polymer 7Q (93.5% cis- Natural
); Mooney vis~
1,4); Mooney vis, ); Mooney vis- rubber
cosity (ML-4), 18
cisoty (ML-4), 60
eosity (ML-4), 54
alone
(control)
Run No
1
2
3
4
Parts by weight:
Ois-polybutadiene _____________________________________ _ _
5
6
7
8
‘
10
'
100
75
50
100
75
50
0
25
50
o
25
50 I
Natural rubber
9
100
75
. 50
0
0
25
50
100
Processing Data
Compounded Mooney (MS 1% at 212° F.)1 _________________ __
24.5
28
32.5
68.5 v
62.5
47
60
58.5 ‘
49.5
‘48
Scorch at 280° F.,2 minutes to 5 point Mooney rise __________ ._
14. 5
l3. 5
13. 5
10. 5
11. 5
12. 5
1O
11
11. 5
11. 5
Extllllllsllgnflt 250° F': a
45 3
45 5
20 3
23 1
35 6
33 4
3e 3
40‘ s
Grams/min
Appearance rarinrr
94
11
n85.0
1].
37.5
6
68.0
7-
87.0'
9- I
71.0
6—'
81.5 (‘H- v
90.0
9+
0
e5 min
See footnotes at end of table.
.
50 1
.
101.5
11+
B'
.
.
.
.
.
.
.
'
51.5
95.0
11-‘—'
3,060,989
TABLE I——Continued
Cured 30 Minutes at 307° F.
Polymer A (81.7X cis~
1,4)‘; Mooney viscosity (MM), 18
Polymer 13 (89.0X cis1,4) ; Mooney viscosity (ML-4), 60
Polymer 0 (93.5X cis1,4) ; Mooney viscosity (ML-4), 54
7
Run No
1
Compression set, percent 4 __________________________________ --
300% modulus, p.s.i.,_80° FLTensile strength, p.s.1., 80° F.5__
Elon%ation, percent, 80° FL.
200° . Max. tenslle, p.s.i.5_
Heat_bu1ld-up, A '1‘, ° F 5
Resilience, percent 7
2
3
9
10
22. 8
16. i
16. 7
17. 3
14.8
15.3
1, 220 l 1, 400
1,480
1,440
1,450
1, 140
1,330
1, 430
2, 120
550
1, 480
58.1
64. 0
3, 000
525
740
55.1
66. 4
f 1, 600
l 320
1,070
50. 3
73. 3
2, 660
440
1, 600
44. 2
70. 4
l 3, 600
f 550
2,430
44. 6
71. 8
2, 200
400
1,170
38.8
77. 5
2, 580
470
1, 640
44. 6
72.1
3, 390
540
2,180
43. 9
71. 2
1 3, 400
f 505
2,750
47. 9
67. 7
22.0
67
2. 5
72
8. 4
G9
20. 0
67
1. 2
70. 5
3. 5
71
20. 9
68. 5
d 13
65
10. 3
18. 9
.2
12.8
e 30
° 30
16. 7
8. 6
5—84
—68
~63
—57
11.0
06. 5
8. 0
Gehruan freeze point, ° C." ________________________________ ._
Ozone rating: 13
—91
—75
—59
(b)
(b)
16.2
(b)
21.7
5
8
3
5
3
3
4
3
3
2
10
10
10
' 10
10
10
10
10
10
4
IASTM D927-55T, Mooney viscometer, small rotor, 212° F., 1.5
1° Goodrich ?exoineter, 257 lbs/sq. in. load, 0.250 inch stroke, 200° F
minutes.
oven temperature. Reported as running time to failure of test specimen
ll ASTM D1053-54'l‘ (modi?ed). Gehman torsional apparatus.
Test specimens are 1.625 inches long, 0.125 inch wide and 0.077 inch thick.
The angle of twist is measured at 5° 0. intervals. Extrapolation to
zero twist gives the freeze point.
12 Samples employed were strips 4 inches long and 0.5 inch wide.
They were mounted in racks where they were elongated 25 percent and
exposed to air containing 50 parts by volume 01' ozone per 100 million
2 ASTM Dl077-55T, Mooney viscometer, large rotor, Scorch in minutes
to 5 point rise above minimum Mooney.
8 No. l/2 Boyle extruder with Garvey die. See Ind. Eng. Chem. 34,
1309 (1942). As regards the “rating" ?gure, l2 designates an extruded
product considered to be perfectly formed whereas lower numerals
indicate less perfect products.
4 ASTM D395—55, Method B (modi?ed). Compression devices are
used with 0.325 inch Spacers to give a static compression for the one-half
inch pellet of 35 percent. Test run for 2 hours at 212° F. plus relaxation
.
8
1,000
6. 2
68
for 1 hour at 212° F.
7
990
7. 7
____ .-
6
25. 5
Time to blowout, minutes 1“ ________________________________ __
Three days
5
2, 240
530
910
61. 5
66. 7
Flex life, thousands of ?exures to failure 8 ................... _Shore A hardness ‘1
Seven days
(control)
4
21.3
Natural
rubber
alone
parts of air. The samples were rated according to the following numerical
(1) Surface slightly dulled.
sys em:
'
5.AS'I‘M D412-51’l‘. Scott tensile machine L-G. Tests are made at
(2)
(3)
(4)
(5)
(6)
(7)
80° F. unless otherwise designated.
5 AS’I‘M D623-52T. Method A, Goodrich ?exometer, 143 lbs/sq. in.
load, 0.175 inch stroke. Test specimen is a right circular cylinder 0.7
inch in diameter and 1 inch high.
7 ASTM D945-55 (modi?ed). Yerzley oscillograph. To; specimen
is a right circular cylinder 0.7 inch in diameter and 1 inch 111
First evidence of attack, “bubbly" appearance on surface.
Roughening of surface, no open cracks.
First evidence of very minute cracks.
Many minute shallow cracks.
Longer shallow cracks.
Deeper cracking, numerous cracks having appearances of very
?ne tight lace.
(8) More serious cracking, growing quite deep.
'
A
‘ ‘EASTM D8l3-52T (modi?ed). DeMattia ?exing machine.
punctured specimen is subjected to a bending action at a constant rate
(9) Lacework of deep cracks.
(l0) Cracks, both deep and numerous.
under certain conditions of stroke and temperature and the rate of crack
growth measured. The DeMattia tester is used in these tests with
a 3-inch stroke, 3-inch wide test specimen with 3 pierces in groove, and
500 ?exurcs per minute at 210° F. The results are reported as thousands
of ?exures to complete break.
9 ASTM D676-55T. Shore durorneter, Type A.
(e) Decreased in rate after second pass.
(1’) Crystallizcd.
(e) Maximum run.
(d) Percent broken at 50.000 ?exures.
(=) crystallized over a wide range.
(*) Estimated (interpolated value from stressstrain curves).
Example' II
Polymers X, E, F, G and H were blended with nat
ural rubber as above and compounded according to the
A number of runs were made wherein natural rubber
following recipes:
was blended with various synthetic rubbers by ?rst band
ing the natural rubber on a roll mill and then adding the
cis-polybutadiene. In this example, several cis-polybu
Parts by Weight
45
tadiencs were utilized as prepared in the presence of ben
zone and a catalyst consisting of titanium tctraiodide
Polymer X, E
Polymer G
and F
and H
(TH) and triisobutylaluminum (TIBA) under the fol
lowing conditions.
50
Polymer- Percent
Polymer
ization
Temp.
F °.
0
0
0
0
0
0
conversion
42
62
64
25
58
87
Milli-
Milli-
Mol
Mooney
moles
TIBA
moles
T’I‘I
ratio
TIBA/
TTI
ML-4 at
212° F.
10.0
1a. 5
9.0
7.5
10.0
11.0
2.5
1. s
1.8
1.5
2.0
2.2
4/1
7. 5/1
5/1
5/1
5/1
5/1
17
is
is
16
120
37
Polymer X is a cis-polybutadiene blend of polymers A~D
and has a ‘blended Mooney (ML-4) of 14. The blend
contained the ‘following percents of the 4 polymers:
Percent.
Polymer __________________ __ 100
50
100
50
100
50
______ __
50
50
No. 1 smoked sheet _______________ __
5
High abrasion furnace black.
50
50
Zinc oxide _________________ -_
3
3
3
3
4
Stearic acid-
2
2
2
2
3
Antioxidant l____
1
1
1
1
Disproportionated rosin-
5
5
Sulfur _____________________ __
1. 75
1. 75
ator) ____________________ __ 9 Var.
(plasticizer) _____________ __
Var.
1 Same as in Example I.
9 Variable.
_
______ __
#1 8.8.
50
1
...................... __
1. 75
1. 75
2
Var.
Var
Var
0. 4
Var.
10
7. 5
5. 0
N - cyolohexyl - 2 - benzothizt
zolesulfenamide (acceler
Aromatic
petroleum
oil
These compositions were cured for 30 minutes at 307°
F. and the properties determined, employing the test pro
cedures listed in the footnotes to Table I. The data ob
tained are given in Table II. Values in Table II listed
With an (E) beside them are interpolated values while
A
___42.7 6
the dashes in this and other tables indicate that that
B
___ 18.4 a
particular value was not obtained.
C _______________________________________ __ 23.3
When one compares the heat build up of the cis-poly
D
_ 15.6
butadiene blend with natural rubber with that of the
Polymer G is a polybutadiene prepared ‘by emulsion
polymerization Whereas polymer H is a 75/25 butadiene/ 7 O blend of emulsion polymer with natural rubber, it is
styrene polymer prepared by emulsion polymerization.
readily seen that cis-polybutadicne blend approximates
Both of these polymers were prepared in processes em
the smoked sheet Whereas the emulsion blend approxi
ploying a sulfoxylatc activated catalyst system at 41° F.
The 75/25 butadienc/styrene was prepared by commer
cial process.
’
mates the emulsion polymer alone. This advantage for
the cis-polybutadieno-natural rubber blend is material
75 in fabrication of heavy duty tires.
‘3,060,989
. ..
10
TABLE II
50/50 blends of high and low Mooney eis-polybutadiene with natural rubber
Polymer e
X
X
E
E
F
NSoé l
G
G
H
H
Parts by weight:
Butadiene polymer ....................................... -_
Natural rubber
Plasticizer, phr,b
Accelerator, phr.b_
100
50
100
50
100
0
100
50
100
50
1.0
50
2.5
0. 8
10.0
0.9
50
7. 5
0.65
5.0
0.9
100
6.0
0. 4
10.0
1.6
50
7 5
1 0
10.0
1.2
50
7. 5
0. 8
Processing Data
Mooney, ML-4 at 212° F ..................................... ._
14
compounded Mooney, MS 1% at 212° F ..................... ..
24. 5
31
Extrusion at 250° F;
Inches/min
Grams/min
43. 3
83.0
38. 5
82. 5
11+
11+
_Rating
...... ..
120
______ __
37
100
44
68
35. 5
41. 5
34
34
30. 5
37
(1)
(1)
39. 0
68.0
32. 5
75. 0
51. 4
104. 0
32. 1
85. 0
32. 5
76. 0
44. 5
110. 0
40. 0
88. 5
(1)
3
8
11
9-
10
11+
10+
14. 8
1, 150
a 2,800
17. 4
1, 380
2,000
19. 9
1, 300
3, 050
20. 4
1, 520
2,120
17. 2
1, 350
3, 330
20. 4
1,400
3, 680
.3
1, 450
a, 530
67
52
Cured 30 Minutes at 307° F,
Compression set, percent
300 percent modulus, p.s.i., 80° F ----------------------------- -Tensile, p.s.i., 80° F
18.0
1, 650
2, 250
Elongation, percent, 80° F ____________________________________ --
200° F_ uni tensile, n i
Heat build-up, A T, "F
Resilience, percent
_
Flex life, thousands of ?exures to failure ...................... _-
11. 6
1, 420
2, 520
365
° 490
420
e 525
380
475
370
540
600
540
1, 135
56. 8
68. 9
1, 930
52. 7
67.0
l, 325
38.8
76. 5
1, 960
49, 7
67.0
1, 120
47. 9
72. 0
2, 270
47. 6
67. 6
1, 125
61. 5
59.3
I, 980
58.1
60.1
1, 660
63. 5
58.2
2, 240
60.8
59. 0
4. 0
26. 0
0.7
29. 7
2. 7
24. 0
23.1
34. 8
Shore A hardness. _ _ _
67
63
63
61
185
550
185
455
° 14. 0
20. 0
3
2
Tear Strength, lb/inch 7 ______________________________________ --
Time to blowout, minutes
17.0
1,370
a 2,800
Ozone rating, 3 days ......................................... ..
1.2
63
(d)
60
58. 5
60
62. 5
...... --
495
255
60
450 '
420
520
° 30. 0
9. 8 ______ ....
9. 0
8. 8
9. 8
9. 9
8. 6
2
3 ______ --
1
2
3
3
4
Oven Aged 24 hours at 212° F,
Heat build-up, AT, "F ....................................... _-
45. 9
47. 3
34. 4
46.6
39. 2
43. 9
55. 4
51. 7
54.1
55, 4
‘Resilience percent
Shore A hardness“.
75. 8
71
70. 3
66
79. 4
65
69. 9
64
77. 4
67.5
68.2
63
64. 8
62. 5
65. 3
64. 5
63. 4
64
62. 1
65
1 Crumbled.
b Phr.=parts by weight per 100 parts rubber.
3 ASTMI 13624-54, Die A.
uX=Blend of cis 1,4-polybutadiene, Mooney viscosity 14 (ML-_4 at
" Test discontinued~no blowout occurred.
212° F.). cis 1,4-content approximately 90%. E~—-c_1s lA-polybutadiene,
‘1 Usually breaks to 15% by 50,000 ?exures (was 11% at 10,000 ?exures).
Mooney viscosity 120 (ML-4 at 212° F.). F=c1s 1,4-p0lybutad1ene,
Mooney viscosity 37 (ML-4 at 212° F.). G=Emulsion polybutadiene.
e Estimated.
H=Butodiene-styrene copolymer.
Example 111
Still another series of runs were made in which natural
rubber was blended with various synthetic rubbers.
Compounding recipes,
parts by Weight
These blends are made up as described _1n Example II. 45
Synthetic
Natural
The polymers, alone and in admixture wlth natural rub-
00113811191;
rulbber
her, were compounded according to the following recipes,
an
after which they were cured for 30 minutes at 307° F‘.
.
.
Compoundrng recipes
parts by Weight
Natural
polymers
rubber
and blends
U0
alone
Polymer ________________________________ __
High abrasionfumace mach
l
____
zinc {ll-me
r
'
Synthetic
1
3
.
.
romatic petroleum oil ______________________ _.
celeretor) __________________________________ __
a one
5
5
1'75
2
Variable
0. 4
issulfurl
( ac
-cyc o 11exy 12
- -b enzo thl azy1 su11enami ae
00
.
1 Same as in Example 1
After the polymers and blends were compounded and
f5 cured, the physical properties. of the materials were de
0
50
A
en S
50
0
terrnlrled for both ‘aged and unagcd stocks. The prop
4
ertles of these stoclcs are tabulated below 1n Table III,
and the test procedures used in determining the properties
321st?“
%
i;
Disproportiona
Variable
0 or 5
'
p
,
_
are described in the footnotes to Table I.
TABLE III.—BLENDS 0F SYNTHETIC RUBBER WITH NATURAL RUBBER
Polymer B or blend __________________________________ __
J‘
K
L
.
. 1+
" K-lJ-l-L. - K+L- No.1 . No. 1
>
8.8.
8.8‘.
L
L+
N0. 1
8.8.
No.1
8.8.
No.1
8.8.
Parts by weight:
Synthetic polymer _______________________________ _.
Natural rubber or synthetic polymer ____ __
100
0
100
0
100
0
100
0
Accelerator, phr _________________________ __
0.8
1 6
1.2
1.2 ~
5
5
5
Disproportionated rosin, phr .................... -_
50
50
50
50
50
50
50
50
.50
50
0
100
0
100
1.0
1.4
0.6 1
1.0
0.8
0.4
0.4
5
5
5
______ __
------ .-
5
5 >
5.
Processing Data
Mooney, ML-4 at 212° F ____________________________ __
compounded Mooney, MS 1% at 212° F ............ __
45
50
44
32
52
33
52 I
34
G)
(1)v
32
(1)
42
(1)
38
29
(1)
30
100
28
100
39
38.8 87.0 V
34.8
96.0
44.0
90.0
37.5
85.5
46.3
94.0
49.5
00.0
52.0
95.0
Extrusion at 250° F.:
Inches/min ______________________________________ __
Grams/min
,
Rating...
See footnotes at end of table.
29.3
61.0
5-
29.0
43.8
80.0 _ 104.0
10+
11+
43.0
105.5
12-
7+
10
10-
11-
11+
11+
11+
3,060,989
TABLE III—C0ntinued
Cured 30 Minutes At 307° F
Polymers or blend
J
K
L
L
J+L
K+L
1+
No. 1
5.8. v
Compression set, percent..-
19.1
27. 4
S.S._
18. 2
20. 2
No. 1
ss.
No. 1
8,8.
.
16. 0
24. 4
300% Modulus, p.s.l., 80°
1,060
1,170
1, 150
1, 740
1,070
1, 200
1,120
1,240
1, 210
1, 240
1,550
2,150 3 2,500
3, 470
3, 750
550
1, 920
2,510
525
1, 020
2, 840
535
l, 460
3,140
585
1, 920
3, 380
610
2, 040
3, 490
635
2, 350
3, 460
605
2, 740
3, 700
535
3, 020
75. 3
5. 0
3. 9
61. 5
11.3
23.0
58. 1
15. 3
4. 5
71.9
6. 3
3. 6
46. 9
14. 1
8. 0
58. 5
' 8. 8
20. 4
63. 5
6. 5
b 56.4
47. 3
6.9
0 12. 5
2. 6
6.4
s 15.0
22.7
24. 8
23. 9
° F. max. tensile, 13.5.1
470
1, 430
2 480
1, 320
Heat build-11p, A T, ° .
Time to blowout, minutes_
. Flex life, thousands of ?exur
41. 9
22. 3
1.4
68. 3
7. 4
2. 8
62
57. 5
59
63. 5
59. 5
59
60
59
59. 5
58. 5
61. 5
7
10
10
10
9
10
8
8
9
3
2
Shore A hardness“
Ozone rating, 8 day _
_______________ ..
665
1, 590
21. 0
L+
No. 1
8.8.
Tensile, p.s.i., 80° F-_
Elongation, percent,
26. 2
K+
No. 1
Oven Aged 24 Hours At 212° F.
300% Modulus, p.s.i., 80° F__
2,180
2,790 ______ -_
2,175
1,625
2,025
1,760
1, 675
1,950
Tensile, p.s.i., 80° F _____ __
Elongation, percent, 80° F"
3, 650
470
3,480
370
1, 650
255
3, 080
400
2, 280
380
3, 000
410
3,150
490
2, 680
450
2.810
410
_____________ __
55. 8
53. 4
47.6
55.1
44. 9
51. 3
54. 1
40. 5
39. 2
Flex life, thousands of ?extures to tail
Shore A hardness
2. 8
64. 5
1. 5
68
0. 9
65
1. 1
65
s 47. 0
63. 5
10. 7
65
8.4
65. 5
33. 0
62. 5
23.0
65
Heat build-up, AT, °
1 Not measured.
Analytical Chemistry 31, 529 (1959). Polymer K is identical to Polymer
G (emulsion polybutadiene) of Example 11. Polymer L is identical to
Polymer H (butadiene-styrene copolymer) 01' Example II. No. 1 5.8.
is top grade smoked sheet natural rubber).
b Broke vertically instea of horizontally.
2 Estimated.
I Polymer J is a cis-polybutadiene which was prepared by polymeriz
atlon at 41° F. using a 5/1 mol ratio of triisobutylaluminum/titanium
tetraiodide. This polymer contained 95.5% cis linkage, 1.0% trans
linkage and 3.5% vinyl linkage as determined by the complete infrared
method described by Silas, Yates and Thornton in “Determination of
Unsaturation Distribution in Polybutadiene by Infrared Spectrometry”,
s Percent broken at 50,000 ?exures.
Example IV
25
Still another series of runs were made in ‘which natural
rubber was blended with a butadiene polymer which contained a very high amount of cis-l,4-con?guration.
Compounding recipes,
Parts by “e‘ght
The _
C,
blends, and the runs in which the cis-polybutadienc and
1 b my
0
N‘jjlii’sglgged $15,121:"
natural rubber were used alone, were compounded ac- 30 Hugh abrsswn furnance bl
d‘
h
f
'
'
T'h
'
I b t
Z1110 oxlde ---------- --
cor mg to tree ared
o ogvmgo1recipes.
e (HS-l, -p0dy1u amerization in to uene iuent
diene was
.
p
p
.
y P ..y
.
.
iggaric
361d 1
non ant _
.
V 1 b1
vglfigblg
08
50
50
50
3
3
21
Disproportionatedr
5
Aromatic petroleum on
5
tetraiodide of 3.75/ 1.0. The cis-polybutadiene used in
ilgeulléaga
3-55
the blends was a composite of polymers from 6 runs, all 35
o
3
21
21
5
5
Variable
using a. mol ratio of trnsobutylalummum to titanium
.
1
100
‘
5
Va “1.152
35
r
'
.
of which were made at 20 F., using water as the short
1 Same asin Example L
stop. The composite, which contained 2 parts/ 100 parts
2 Same asm Example In
rubber of phenyl-beta-naphthylamine, had a Mooney
‘
_
viscosity (ML-4) of 26, and a cis content of 91.4 perAfter compounds, the rubbers were cured for 30 mm
cent, a trans content of 4.4 percent, and a ‘vinyl content 40 “lets at 307° F- EXWPt Where ?o'fed- The physm?ll Drop
of 4.2 percent as determined by the infrared method of
?fties 0f the (“Red rubbers, which were detefmln?d by
Silas, Yates and Thornton referred :0 in the foot-note
the test procedures referred to 1n the footnotes to Table I,
to Table III.
are recorded below in Table IV.
‘
TABLE IV
Polymer or blend __________________________ _-
M
N
P
R
S
T
V
X
Parts by weight:
Gis-polybutadiene _____________________ __
Natural rubber___
_____ __
Accelerator, phr_-__
_____ __
Disproportionated-rosin, phr __________ __
0
100
0. 0
5
10
90
0. 64
5
25
75
0- 7
5
50
50
0. 8
5
75
25
0. 9
5
90
10
0.96
5
100
0
1.00
5
50
50
0.8
0
36
34. 5
34
32.5
32. 5
41. 5
48. 5
94. 0
11
47.9
99. 0
11
46. 5
101. 0
11
44. 0
96. 5,
41. 0
91. 0
46. o
96. 5
11+
11
11+
Processing Data
.Oompounded Mooney, MS 1% at 212° F_-__
Extrusion at 195° F.:
ches/min--Grams/min-
36. 5 > _______ __
2
__
Rating ___________________ -_
45. 5
s5: 5
11+
48. 4
90. 5
11
Cured 30 Minutes at 307° F.
'
l
Compression set, percent __________________ _-
300% Modulus, p.s.l., 80°
Tensile strength, p.s.i., 80° FElongation, percent, 80“ 11-
___
_
, 18. 3
18.2
16. 6
l7. 8
18. 0
18. 5
19. 2
16. 5
1,300
13, 050
1, 320
3, 570
1,450
3, 480
1, 320
3,080
1, 280
2, 410
1, 230
2,150
1,100
1 1, 900
1,500
3, 030
_
l 575
555
560
550
460
440
l 440
500
200° F. max. tensile, p.s.i_
_
2, 715
2,650
1 2, 500
1,935
1, 180
1, 030
915
1,780
Heat build-up, A T, ° F__
Resilience, percent-______-
_
_
46. 0
68.6
46.3
68. 5
46.3
69. 1
49.0
68. 0
49. 3
69. 4
4o. 3
71. 3
51.0
70. 9
49. 3
71. 6
Time to blowout, minutes .... __
_
9. 0
10. 5
14 4
15. 8
l 15
15. 5
16. 8
8. 8
Flex life, thousands of ?exures to failure__
-
2 15
2 16
i 14. 5
12.1
5. 6
2. 4
1. 3
18. 0
Shore A hardness _________________ _-
..
58
59
60. 5
60
62
62
62. 5
63
455
530
420
430
280
V 155
175
530
Tear strength at 80° F., lb.linch__
See footnotes at end of table.
3,060,989
13
14}
TABLE IV—C0ntinued
Oven Aged 24 Hours at 212° F.
Polymer or blend __________________________ _.
M
300% modulus, p.s.i., 80° F ................ -.
1 1, 575
Tensile strength, p.s.i., 80° F.-
N
P
R
S
'1‘
V
X
1, 590
1,680
1-, 950
1 2, 200
2,100
2,010
1 2,050
1, 700
1, 620
1,550
2, 260
Elongation, percent, 80° F...
Heat build-up, A '1‘, ° F_-..-
l 415
43.3
375
45. 6
360
43. 9
1 340
44. 9
265
45. 6
240
43. 6
220
48. 7
310
48. 7
Resilience, percent ............... ..
71.1
08. 2
71. 9
72. 3
72. 8
76. 2
75. 5
72.9
Flex life, thousands of ?exures to failure.
.Shore A hardness .......................... --
35. 0
61
20. 4
62. 5
47. 4
63.5
14. 6
64. 5
1. 8
67
<0. 1
<0. 1
68
2 56. 7
‘66
1 Estimated.
2,080
2 Percent broken at 50,000 ?exures.
Example V
The results of these tests are tabulated below.
A series of runs was made wherein new 7:60 x 15 tire
carcasses were retreaded by using half and half retread 20
construction, i.e., 1/2 of the tire circumference 1s covered
with one tread composition and VV; with a second tread
composmon. These ‘ores were placed on a Dodge sta-
‘
PM Tqtal Miles] Rating
Tlre
Tread
Sulfur mnes
Lu“ 50/50 testbkmd” 2
Tread
NR=100
crackmg
97782
968
9,782
77. 6
100
50/50 test blend-. 11.25 7,341
Naturalrubber.. 2
7, 511
04.7
76.2
124 None.2
100 Extensive
tetra1od1de catalyst. Infrared exarnlnatron of polymer
50/50 testblend" 2
127245
ml
121 None_
used 1n the tests according to the method of Silas, Yates
and Thornton referred to 1n the footnote to Table III in
Naturalrubber-- 2
3_____ 50l50testb1end“ 2
12, 245
3,236
70.4
73.9
100 Extensive
116
mm
3, 235
53.5
100
Do.
4—---— ?sglg‘r’gffffflffi % 75 328 ‘£13
50/50 test blend.. p75 2,
gig
g3
g3:
Bo!
118
Do_
111011 Wagon operatmg on a regular route in the southwest.
'
-
.
’
Natural rubber“
.'
The C18 polybutadiene Tabb?- was one Prepare? a? m 25
Example I, employmg a trnsobutylalurmnum-utamum
'
'
.
‘
'
.
-
_
d1cated that the polymer contamed 95 percent ms, 2 per- 30
cent trans, and 3 percent vinyl con?guration. These
polymers contanied 1.8 percent phenyl-?énaphthylamine
.
.
antioxidant. All polymers were gel free.
-
-
SBR .......... --
I
753
3
50”) 75.61."? 1.75 8,
(713-3
--.__
'
5
es
35
en
,
9, 722
gags?‘ test blend. 11275
337
""""" “
’
.
41° F. ThlS rubber had a mean ML-4 Mooney at 212° 40
F. of 52.
The natural rubber was premasticated #1 Smoked
Sheets.
_ The rubbers were compounded according to the followmg compounding recipes.
‘
'
1
'
'
1.
'
’
Extensive
surface.
S111‘ 306.
S111‘ ace.
0.
1(1)?
go.
100
Do.
p4
go.
00
0'
.
1.75
copolymer containing 24 percent bound styrene prepared
by emulsion polymerization in an iron-activated recipe at
125 None‘
_‘
6,553
..
.......... __
The SBR (styrene-butadlene copolymer rubber) was a
o.
71.8
7
'
'
h
.
-
'
h
a $533,133.52 51,; $8,553,135
- -
h‘
'
hem“ lazylsuuenamlde
.
Example VI
45
.
Four truck tires were capped 1/2 with blend as in EX
ample V and 1% with natural rubber. The blend had a
2 parts by weight of sulfur per 100 parts of rubber in the
Compounding recipes,
D51Its by Weight
.
_
4_____ 50/50 testblend“
-
551313
1.75
__________ __
Mooney vis-
cos1t1es were 35 to 45 (ML-4 at 212° F.) unless otherw1se
lndlcated-
2
compounding recipe whereas with the natural rubber 2.25
l?gglgil SBR 50 parts by weight of sulfur per 100 parts of rubber was used.
The cis~po1ybutadiene used in preparing the test blend
.
was a blend of polymers obtained from 6 runs carried out
C1s-p0lybutad1ene .................... . .
50
Natural rubber _______________________ -_
50
................ --
100
______ _-
accordlng to the Sm1th et al. method as descnbed 1n Ex
gag-55,35,011 furnace blacknrnn?njj
ample I. The products from two of these runs were ex
50
50
128
Zinc oxide
_
3
3
3
Steam: ac1d_.
-
3
3
1
Antioxidant ____________
_
1
1
1
. . . ..
5
D's
‘o
0
to
at
d
s~
_ _ _ ._ __
Alhlféhfygrlorllluatt‘ie £2 1513mm on ______ __
Sulfur.1 __________________ _. __________ _.
5
Variable
_
5
_
_
amined by infrared analysis according to the method of
55
.
.
.
Sllas, Yates and Thornton menuoned 1n the footnote
................ --
2
_
10
1.75
‘
'
to Example III and found to contam 93.6 and _94.4 ms
1,4-add1t1on.
These tires were 10.00 x 20 truck tires and
Ng‘g?‘ffilfff'ff‘ilff?nffffilf‘flfl
0_ 6 ________________ __
Were placed on trucks to be tested by the Armstrong Test
N-cyclohexyl-2-benzothiazylsulfenamide .......... ..
0. 4
1.2 60 Fleet at San Antonio, Texas. At the end of approximate
ly 3,000 miles, the following data was obtained.
Tire
Tread
Total
miles
Miles/
.001”
Rating
Tread
NR=100 cracking
Remarks
W931‘
1 ____ __ Natural rubber....
2 .... _-
3 .... .-
41
100 'None....
50/50 test blend.-.-
3,128
45
110 ...do..___
Natural rubber..-_
3,128
40
50/50 test blend....
3 128
44
Natural rubber._-.
50/50 test blend.-.-
3,128
3,128
40
43
1
53
}Oarcass failure between shoulder and
4 .... .. Natural rubber.._.
50/50 test blend..._
3,128
2,919
2, 919
65
a
side wall.
3,060,989
15
16
From the above examples, it can be seen that tires
The foregoing data show that the all-synthetic com
position (cis-polybutadiene and cis-polyisoprene) has
treaded with the blend of cis-polybutadienc and natural
rubber are generally superior to the natural rubber alone
and to a commercially acceptable cold rubber.
properties which compare favorably with those of the
natural rubber composition.
Example VII
Example VIII
Butadiene was polymerized to cis-polybutadiene in a
series of runs using a triisobutylaluminum-titanium tetra—
A cis-polybutadiene prepared as described in Example I
was blended in equal weight proportions with a synthetic
cis-polyisoprene, which was a sample of Natsyn rubber
iodide catalyst system.' The polymers were blended to
give a product having the following characteristics:
(Goodyear Tire and Rubber Co.) (Chem. & Eng. News,
Mooney value (ML-4) at 212° F _____________ __
36
Ash, percent
__ 0.14
Ian. 19, 1959, p. 50). Based on a standard sample of
natural rubber containing 98 percent cis 1,4-additi0n, this
cis-polyisoprene was determined by infrared examination
Inherent viscosity
2.23
to contain 90:2 percent cis l,4-addition and 4.5 $0.2 per
Gel, percent
0
15 cent 3,4-addition. This blend and also synthetic cis-poly
Infrared examination of the cis-polybutadiene by the
isoprene alone and natural rubber alone were com
method of Silas, Yates and Thornton mentioned in the
pounded in accordance with the following recipes:
footnote to Example III indicated that the polymer con
tained 94 percent cis 1,4-addition, 2.3 percent trans 1,4
addition and 3.7 percent 1,2-addition. The polymer con 20
Compounding recipes, parts
by weight
tained 1.79 weight percent phenyl—beta-naphthylamine.
The cis-polybutadiene was blended in equal weight pro
portions with a synthetic cis-polyisoprene and with natural
rubber.
1
The cis-polyisoprene was a sample of Coral
50
50
100
Natural rubber__
Pepton 22 1__
Philblack 0 it...
Zinc oxideStearic acid
50
3
3
50
3
3
Flexamine 2
1
1
l
Philrich 5 3731 a30 Resin
Pine tar
5
5
on a comparison with a standard sample of natural rub
isoprene was determined by infrared examination to con
tain 89i2 percent cis 1,4-addition and 7.61:0.2 percent
3,4-addition. These blends were compounded using the
3
Cis-polybntadiene ____________ ._
Cis-polyisoprene (synthetic) __
rubber (Firestone Tire and Rubber Co.) Which is de 25
scribed more completely in “Coral Rubber-A Cis 1,4-Po1y
isoprene,” Ind. and Eng. Chem. 48, 778 (‘1956). Based
ber containing 98 percent cis 1,4-addition, this cis-poly
2
________ . .
100
0. 5
50
3
3
Retardcr W 4
following formulations:
Sulfur ______ __
2
2. 25
2. 25
NOBS Specie
0.8
0. 7
0.5
1 Di-o-benzamidophenyl disul?de.
Compounding
recipes, parts by
weight
35
1 As in Example I.
8 A disproportionated pale rosin stable to heat and light.
4 Salicylic acid with a dispersing agent.
Physical properties of the above compositions were de
1
2 ,
Cis-polybutadicne _______________________________ __
50
Cis-polyisoprene _________________________________ __
50
50
________ __
Natural rubber
50
Philblack O 1 ____________________________________ __
50
.50
Zinc oxide
3
3
Stearic acid _______________________________ .. ____ -_
Flexamine L _
__-_ _
3
1
3
1
Philrich 5 ii...
_____ __
Resin 731 D 4 ____________________________________ _-
5
5
5
5
Sulfur
2
2
NOBS special 5__________________________________ __
0. 7
0. 6
1High abrasion furnace black.
termined, and the results are set forth below in Table VI.
40 It is noted that the ?rst three properties tested in the table
are for the compositions in their uncured state while the
other properties are for compositions cured for 30 min
utes at 307° F. The physical properties were determined
according to the test procedures described in the foot~
notes to Tables I and VI.
TABLE VI
.
1\
22
33
=Physical mixture containing ‘65 percent by weight of a
complex diarylamineketone reaction product and 35 percent
by weight of N,N’-diphenyl-p-phenylenediamine.
MS 1% at 212° F ___________________________ __
26
18
29
3 A highly aromatic oil.
4 A disproportionated pale rosin stable to heat and light.
Scorch at 280° F., min. to .5 point Mooney rise.
26
18. 5
0. 5
Extrusion rating, Garvey die _______________ _.
11+
5 N-oxydiethylene-Z-benzothiazylsulfenamide.
v><104, moles/cc.4 __________ __
11
l. '74
Compression set, percent.
19. 8
11+
1. 53
1. 88
'21. 9
15. 4
One set of samples was cured for 30 minutes while an
other set was cured for 45 minutes, both at 292° F. Re
300% Modulus, p.s.i., 80°
1,565
1,640
2, 135
Tensile, p.s_.i., 80° F ______ __
2,680
3,035
3, 790
sults ofdeterminations of physical properties are set forth
below in Table V. The physical properties were deter
mined according to the test procedures referred to in the
footnotes to Table I.
Heat build-up, AT, °
___
40. 5
43.9
39.5
Resilience, percent _____ __
72. 3
71. 9
73. 2
TABLE V
Elongation, percent, 80:1 F
Time to blowout, minutesAT, 9 F. at 10 min ____ __
_
Shore A hardness.--
60
1l
440
Abrasion loss, grams ______________________ __
495
485
22.0
10. 8
l4. 8
90. 0
175. 4
107. 6
65
63. 5
70
7.07
10. 60
8. 42
1 50/50 blend of cis-polybutacliene and cis-polyisoprene.
21
I Cis-polyisoprene.
3 Natural rubber.
30 minute cure at 292°F.:
’
Compression set, percent ____________________ __
27. 5
34. 8
300% modulus, p.s.i., 80°F ___________________ __
Tensile, p.s.i., 80°F __________________________ __
1,100
3, 480
980
3, 310
Elongation, percent, 80°F .... _Heat build-up, A T, °F ______ _V
Resilience, percent .......... _.L_
Shore A hardness ____________________________ __
45 Minute Cure at 292°F.:
,
570
43. 3
70. 7
56. 5
625
53.0
67. 9
54. 5
300% modulus, p.s.i., 80°F ___________________ -.
Tensile, p.s.i., 80°F _______ __
1, 040
3, 080
1,190
3, 470
510
590
40. 9
45. 9
71. 7
70. 6
"
Elongation, percent, 80°F. _ __
_
Heat build-up, A T, °F ______ __
Resilience, percent _______________ _-___
__
~ '1 50/50 blend of cis-polybutadiene and cis-polyisoprene.
1 50/50 blend of cis-polybutadiene and natural rubber.
4 Determined by the swelling method of Kraus as given in Rubber
World, October 1946. This value is the number of e?ective network
chains
unit volume of rubber. The higher the number, the more the
65 rubberper
is crosslinked (vulcanized).
_
i Determined by noting the loss in weight of a doughnut shaped rubber
wheel which has been subjected to the abrasive action of a carborundum
wheel on the angle abrader for a certain length of time. The wheel used
is 24 inches in diameter, 1% inches thick, Grade M, Vitreous, grain size
No. 36 alundum purchasedirom Norton Com any, Worcester, Mass.
The normal test conditions are 15° angle, 3312 pounds load and 3,000
70 revolutions.
The foregoing data' show that theall-synthctic composi
tion has properties which compare favorably with natural
rubber, particularly as _regards heat build-up, blowout
' time, and abrasion loss.
I
3,060,939
17
Example IX
The rubber compounds 1, 2 and 3 of Example VIII were
used to make three-way retreads on 7.60 X 15 tire car
casses. The following results were obtained after the tires
were run 3,083 miles:
Tire tread
1. 50/50 blend ________________________ _-
Miles/
0.001”
Wear
58. 3
Tread
Rating 1 cracking
114
the range of 90 to 10 parts by weight of ‘a cis-p'olyiso
prene, the aforementioned parts by weight ranges being
based on 100 parts by weight of total rubbers contained
in the blend; and vulc'anizing the resulting blend.
8. A method of preparing a blend of rubbers which
‘comprises blending in the range of 25 to 75 parts by
weight of a polybutadiene formed by cis 1,4-, trans 1,4
10 and 1,2-addition, at least 75 percent of said polybutadiene
being formed by cis 1,4-addition of 1,3-butadiene within
None.
2. Cis-polyisoprene____
50. 4
98
Do.
3. Natural rubber ____________________ __
51.3
100
D0.
18
and 1,2-addition, at least 75 percent of said polybutadiene
being formed by cis 1,4-addition of 1,3-butadiene within
the range of 75 to ‘25 parts by weight of a cis-polyisoprene,
the aforementioned parts by weight ranges being based on
100 parts by weight of total rubbers contained in the
1 Natural rubbeFIOO.
blend; and said polybutadiene having a Mooney ML-4
15
As will be evident to those skilled in the art, many
viscosity in the range of ‘10 to 130 as measured on a
variations and modi?cations can be produced which fall
within the spirit and scope of the disclosure of this in
vention.
We claim:
Mooney viscosimeter ‘at 212°
v9. A method of preparing a blend of rubbers which
comprises blending in the range of 40 to 50 parts by
weight of a polybutadiene formed by cis 1.4-, trans 1,4
and 1,2-addition, at least 75 percent of said polybutadiene
1. As a new composition of matter, a blend of rubbers
comprising (1) in the range of 110 to 90 parts by weight
of ‘a polybutadiene formed by cis 1,4-, trans 1,4- and 1,2~
‘addition of 1,3-‘butadiene, at least 75 percent of said
polybutadiene being formed by cis 1,4-additi'on of 1,3
butadiene and (2) in the range of 90 to 10 parts by weight
of a cis-polyisoprene, the aforementioned parts by weight
ranges being based on 100 parts by weight of total rubbers
contained in the blend.
2. The vulcanized product of claim 1.
3. The composition of claim '1 in which said cis-poly
isoprene is natural rubber.
4. The composition of claim 1 in which said cis-poly
being formed by cis 1,4-addition of 1,3-b-utadiene within
the range of 60 to 50 parts by weight of a cis-polyiso~
prene, the aforementioned parts by weight ranges being
based on 1100 parts by weight of total rubbers contained
in the blend and said polybutadiene having a Mooney
ML-4 viscosity in the range of 20 to 60 as measured on
a Mooney viscosimeter at 212° F.; incorporating sulfur
30 into the resulting blend; and heating the blend so as to
isoprene is a synthetic cis-polyisoprene.
5. As a new composition of matter, a blend of rubbers
comprising (1) in the range of 40 to 50 parts by weight 35
of a polybutadiene formed by cis 1,4-, trans 1,4- ‘and 1,2
e?ect vulcanization.
10. In an automotive tire comprising 'a carcass and
tread, the improvement which comprises a tread pre
pared from the composition of claim 1.
References Cited in the ?le of this patent
"addition of 1,3Jbutadiene, at least 85 percent of said poly
butadiene being ‘formed by cis 1,4-addition of 1,3~buta
diene and (2) in the range of 60 to 50 parts by weight
of a cis-polyisoprene, the aforementioned parts by weight
ranges being based on 100 parts by ‘weight of total rub
bers contained in the blend.
6. The composition of claim 5 in which said poly
butadiene has a Mooney ML-4 viscosity in the range or“ 45
20 to 60 as measured on a Mooney viscosimeter at
and incorporating a
vulcanizing agent into the resulting blend.
UNITED STATES PATENTS
2,688,605
2,832,759
2,953,556
2,977,349
Tucker ______________ __ Sept. 7,
Nowlin et a1. ________ __ Apr. 29,
Wolfe et a1. _________ __ Sept. 20,
Brockway et a1 ________ __ Mar. 28,
1954
1958
1960
‘1961
OTHER REFERENCES
Binder: “Microstructures of Polybutadiene and Buta
212° F.
diene-Styrene Copolymers,” Ind. Eng. ‘Chem, volume 46,
7. A method of preparing a blend of rubbers which
comprises blending in the range of 10 to 90 parts by
No. 8, August 1954, pages 1727-1730.
Rubber World, volume 138, No. 2, May 1958, page
weight of la polybutadiene formed by cis 1,4-, trans '1,4~ 50 280 relied upon.
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