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Патент USA US3022277

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3,022,267
United States Patent h?ce
Patented Feb. 20, 1962
2
11
HardnessRockwell' ASTNI D;-7 85-5 1
3,022,267
R-sca'le ____________________ __ 815-925.
STABILIZED ISO'FACTIC POLYPROPYLENE
Melting point, ° F; __r.-.._- ______ __» 330-350.
AND METHOD
Speci?c heat-K ca1./gm., ‘’ C. _'__-__.0.4'6;
David- W.‘ Young, Homewood; IlL, assi'gnor to Sinclair 5
X-ray diffraction pattern of isotactic polypropylene in
Re?ning Company, New. York, N.Y., a corporation of
terms of Bragg spacings‘ (d/n.) and intensities}
arne
I
d./n.
631 A.
_ Filed. May 14,1953, Ser. No. 735,130
No Drawing. Filed-May; 14,1958, Se'r. N0.v 735,130‘
6 Claims. (Cl; 260-453)
int.
10
5.26
10
'
Fun-meac
4.81
This‘ invention concerns a novel composition which
4.22
comprises a major amount of isotactic polypropylene and
4.08’.
3.51
3;l2
2.12
a minor amount of a high molecular weight amide, in par
ticular N-stearoyl p-amino phenol.
Isotactic polymers are head-tail-connected linear poly 15
mers, the monomer units of which ('CH2=CHR) are dis
Natta, in 37, La Chimica and Industri'a (-Milan')’, 8'8'-8
tinguished by a simple,’ regular structure incapable of
stereoisomerism. Their chains consist of sections which
900v (19551), attributes’ to the isotactic structure certain
properties which‘ had previously not been found" in By;
tertiary C atoms of‘equal steric con?guration. In iso 20 drocarbons'. At ambient temperatures; these high-molecu
lar-weight polymers are actually hard, crystalline solids.
tactic polypropylene, the “R” group of'the formula is a
The low-molecular-weight isotactic polymers exhibit- like}
CH3 group. The structure of this polymer is illustrated‘
wise ahigh degree‘ of crystallinity; For example, isotactic
inl97, Scienti?c American, number 3, pages 102 and 103
polypropylene specimens with a molecular weight of
(September 1957).
about 2,500 present the‘ same crystalline polymeric‘ struc-_
The advantages of isotactic polymers have been cited
ture as those polymers which have weights of several’
by Natta in 68, Angewandte Chemie, 393—403. (1956).
hundreds of thousands. The isotactic polymers‘ are of
These high-melting thermoplastic polymers, obtained from
great resistivity towards isomerization'eifects', which would
low-priced starting materials, yield ?bers of' great tensile
modify the con?guration of‘ the branched methyl group‘,
strength, which are useful as- textile raw materials. Iso
exhibit a uniform reiteration of monomer units with
tactic polypropylene threads have a tear strength up to 30 even in the presence of catalysts‘ which act by an: ionic)
mechanism. Prolonged heating to 300450" C. in the
absence of‘ catalysts (or else to lower temperatures‘, but
in the presence of various reagents which‘ act’ by‘ a free
more than 7 g./den. (.70 kg./ sq. mm.), comparableto the
strengthof steel, but witha speci?c gravity of one-eighth
as,- high as that of iron.
Isotactic polypropylene sur
passes polyethylene in many properties. This polypropyl 35 radical mechanism), may cause a depolymeri'z'ation of the
macromolecules, although not to a very largev extent.
ene has an averagemolecular weight. generally of from
There are noteworthy differences in the- degrees of
about 100,000 to 1,500,000Staudinger. The CH3 groups
solubility between isotactic and‘ non-isotactic polymers,
are. located onthe same side of, the carbon chain inv a
which contain irregularly’ distributed carbonium atoms of
helical structure, characterized by an identity period gen
diverse steric con?gurations, as shown-in Table I.
erally of from about 6.5 .to 6.6 A. along the axis of the
TABLE“ r
'
l-order
Intrinsic
Polymer
Experim. ~‘transition
viscosl
spec.
100 ccJg.
gravity
I
Soiubilityinv
2 Initial
- a
temp,
fusion
_
‘’ O.
temp;
- Ether
;
High-gnolecular-weight crystalline polypropylpolypropyli
ens.‘
.
0. 92'
158-160- . _______ _. -Insol'__-- -Insol-.._- S011
0.17
0391
I49E ........ __ ‘Insulin. Sol ____ .. Sol;
.
1
Amorphous polypropylene .4 ____________________ -.‘
'
0.55
.
0.85- . ......... .-
.
75
I
p
Toluene
2.40
.
crystalline
~
tame
0116.
Low-nalolecular-weight
1
v
n-Hep-
.
‘S01 ____ __
'
.
.
.1
..
.
Sol ____ -_ ,Highly sol.
rDeterminedat‘135""0: using tetralin as asolveut;v
2‘isotactic.
3 Made
by depolymerizingv the hlgli-molecular-weight. crystallinematerialist-335? C. lntattetra'lin solution-ands nitrogen
atmosphere.
4 Atactic-mode according to'conventlonal procedures.
A product‘ which is insoluble in‘ boiling n-heptane is
principal: chain. It has: a- high melting point v(e.g. 346°
practically completely‘ crystalline.“ An‘ ether-extracted
polypropylene product. is‘co'mpletelly amorphousv and’ has‘
and: is-"assolid'; highlytcrystalline substance with; for‘v
instance, the. following ‘physical. properties:
Speci?c.gravity‘..__._e___.g_.. ____ _, 0.90.4092.
60
Tensile strength ASTM Dl638052T
presents elastomer-like properties;
lbs./ in. 2 _.., _________ __,..___..._.._ 4,600 to 5,400‘.
Stiffness (?evual) ASTM D-747-50
lbs/in."z
.._____ ______ __, ____ _____
130,000
65
1/2.” x. 1/2.” bar ASTM D—256~54T
ft. lb./in. ________ -F _________ __
19..
Fusiontemperature, ° F. _____ -_,_.._ 31.6.4 to 3.38.
Compressive strengthvASTM D‘—695—
54 lb./in. 3 _________________ __ 9,500-1.1,00.0.
Dielectric constant
sec.)
(106
These isotactic polypropylenes can be‘ prepared‘ from‘.
propylene with Ziegler type catalysts inclu'dingcomplexes‘
to 170,000
Impactstrength Izod test unnot'ched.
cycles/
__._.. ____________________ __ 2,0---2.1.
a much lower transistion temperature. After' sulfochlo
rination andvulcanization treatments, the amorphous'type'
consisting of'several substances; for‘ instance, the chloridev
of a metal with an un?lled electron shell,‘ and: an‘organo?
metallic co‘mpoun'cl‘, under‘polymerizationconditions in
cluding temperatures" above‘ ambient‘ temperatures; ezg;
from about 68°‘to 302° F. and‘pres'sures‘ from about at
mospheric or less up tov about 30satmo'splieresj o'r'mo're';
7.0 With catalysts ofjihigh selectivity‘; very'h‘igh yields of
isotactic ‘polymers maybe obtained.‘ The" formation of
3,022,267
3
4
.
Natta has found that the production of isotactic poly
merizates of alpha-ole?ns requires the presence of solid
This invention consists in mixing with the isotactic
polypropylene 0.005 percent to 5 percent of a high
molecular weight amide which is soluble in the polymer,
that is, N-stearoyl p-ann'no phenol to produce an oxygen
catalysts which are chemically bound to the growing
stabilized product.
amorphous, non-crystalline polymers may be almost com
pletely prevented.
polymer chain. It is probable that such stereospeci?c
N-stearoyl p-amino phenol is sold under the trade name
catalytic processes are based on the chemisorption of the
“Suconox-IS.” It is a white solid which melts at 131
134° C. (268—273° F.) and can, be heated'to above 250°
monomer-molecules on the surface of the solid catalyst,
and that the adsorbed molecule presents itself always in
C. (482° F.) without any detectable evidence of decom
position, and appears to be non-toxic. In “Suconox-l8”
a de?nite orientation on the growing chain.
the “stearoyl” group is a mixture derived from com
This type of catalyst is characterized by the presence
of compounds of a metal of the fourth to the eighth
group of the transition elements in a lower stage of oxida
tion. The structure of their atomsjis characterized by
mercial stearic acid and is, theoretically, primarily
C117H35CO.
N-stearoyl p-amino phenol is prepared in general by
the incompleteness of the d-shell. Their compounds, in 15 reacting an approximately equimolar amount of stearic
anhydride or dry stearic acid with the amino-phenol in
a lower stage of oxidation, can enter into associations
with metal hydrides or with metal alkyls, whereby com
plexes are formed in which metal-hydrogen or metal-alkyl
linkages are found in a highly polarized form.
In practical operation, the best catalysts are obtained 20
from Ti, V, Cr and Zr. The polymerization catalysts
arerproduced by reacting compounds of these metals with
alkyls or hydrides of Na, Li, Ba or Al. Compounds of
a lower stage of oxidation, such as VCl2 and TiCl2, enter
into combinations with the metal hydrides or metal alkyls.
This results in the formation of catalysts which act by
an anionic mechanism. These catalysts are heterogene
ous, due to the presence of a solid phase, which may be
colloidal in dimension or microcrystalline.
the presence of a solvent or water-entraining agent such
as benzene, toluene or xylene. The solid product is
then dehydrated by evaporation and the product is ob
tained in relatively pure form.
.
The N-stearoyl p-amino phenol can be used in iso
tactic polypropylene over the concentration range of 0.005
percent to 5 percent. However, best results are obtained
at about 0.01 to 0.25 percent by weight. It is important
' to obtain adequate dispersion of the N-stearoyl p-amino
phenol in the polypropylene and this can be done by
mixing the N-stearoyl p-amino phenol with the polymer
isotactic polypropylene at a temperature about 5 to 10°
F. above the crystalline'melting point of the polymer and
Typical catalysts with an anionic mechanism-activity 30 holding this temperature for about 2 to 5 minutes, then
removing the heat and letting the temperature drop to
cool the mixture at the rate of about 15 to 30° F. in
alkyls, solid crystalline lower halides of metals of the
about 7 to 10 minutes. The polymer and anti-oxidant
preferred transition element group. The quantity of
are agitated together as the system is cooled and the
metal alkyl required for accomplishing maximum catalytic
activity, is relatively small: e.g. 0.1 mol. AlRa per mol. 35 mixture reverts from a liquid to a solid.
When the isotactic polypropylene with 0.1 percent N
of the halide of the transition element. Natta found it
stearoyl p-arnino phenol is placed in a watch glass and
advantageous to operate with an excess of this metal
held for 15 days in a circulating air oven in the dark
alkyl compound, to exert a protective activity by destroy
at 150° F. the product shows no change in color. An
ing oxygen and moisture which may be present in trace
amounts. Otherwise, these substances might poison the 40 isotactic control with no anti-oxidant present gave a
are those which are obtained by treating, with metal
catalysts. Using the terminology developed for cationic
product in the same type test at the same time that was
catalysis, Natta hypothesizes that in this type of anionic
dark brown in color. The results are recorded in Table H.
TABLE II
catalysis‘ the transition element compound may be re
garded as the catalyst and the other compound, alumi
num trialkyl or aluminum dialkylhydride, for instance,
as the co-catalyst.
Isotactic polypropylene
Natta'also found (69, Angewandte Chemie, 213-219
[1957]) that the ?nal reaction velocity after an initial
adjustment period is a linear function of the amount of
the crystalline constituents of the catalyst and remains
constant for a long period of time, sometimes more than
Property
50"
Original
Original
after 15
days at
150° F.
thirty hours, when the concentration of the catalyst is
Original
plus 0.1%
N-stearoyl
p-amino
phenol
after 15
days at
150° F.
'su?iciently low. The rate of reaction is also a linear
M.Pt., ° F .................... __
330
384
332
function of the‘ propylene partial pressure. The energy
Mo]. weight __________________ __
159, 000
47, 000
144, 000
of activation of the over-all process lies at approximately 55
12,000-14,000 kcal./kmol., a value which is lower than
Isotactic, polypropylene has found uses as an addi
that found in most of the radical-activated polymeriza
tive in wax, white oil, soap and other compositions. This
tion processes. The number of active centers created by
invention provides a means whereby the isotactic poly
the interaction between aluminum triethyl and titanium
propylene may be stabilized when admixed with other
tnichloride surfaces does not vary markedly with time, 60 materials as well as when it is used asthe major con
if the catalyst has attained the ?nal state.
stituent of ?ber, ?lm or other materials, along with suit
As has been pointed out above, isotactic polypropylene
able amounts of other additives such as plasticizers, etc.
made according to the process outlined by Natta has valu
Although N-acyl p-amino phenols have been suggested
able properties for use as a synthetic ?lm or ?ber. How
in US. Patent No. 2,654,722, as a suitable stabilizer for
ever, it has been found that exposure of this material to
various conventional polymers and elastomers of the more
light and air causes a darkening of such ?lm and ?ber 65 or less highly cross-linked type, these materials are ap
products which seriously a?ects their marketability. Since
parently attacked by oxygen in a di?erent manner from
these polymers are essentially paraf?nic in nature, and
the attack by oxygen on isotactic polypropylene, since
since the linearity of them is due to the absence of any
few materials which will stabilize cross-linked polymers
active centers along the polymer chain, it is hypothe 70 have any stabilizing e?ect on isotactic polypropylene, and
sized that the polymer molecule is attacked at its end,
since N-stearoyl p-amino phenol has a better stabilizing:
since Natta theorizes that a vinylidene group appears at
the end of the molecule when it breaks away from the
polypropylene.
effect on isotactic polypropylene than on non-isotactic
“growing surface” of the catalyst. This invention, how
ever, is not to be limited by this theory.
I claim:
75
'
1. A composition of matter consisting essentially of
3,022,267
5
solid, crystalline isotactic polypropylene and 0.005 to
5 percent of N-stearoyl p-amino phenol.
2. The composition of claim 1 Which contains 0.01 to
6
,
6., The method of claim 4 which includes cooling the
mixture at the rate of about 15 to 30° ‘F. in about 7 to
10 minutes, after the holding step.
0.25 percent of N-stearoyl pqamino phenol.
3. The composition of claim 2 resulting from mixing 5
the ingredients at about 5 to 10° F. above'the melting
References Cited in the ?le of this patent
UNITED STATES PATENTS
point of the polymer.
4. A method of stabilizing a solid, crystalline isotac
tic polypropylene composition which comprises mixing
the polypropylene and 0.005 to 5 percent by weight of N 10
stearoyl p~amino phenol at a temperature about 5 to 10°
F. above the crystalline melting point of the polypropyl
ene and holding the mixture at this temperature for about
2,654,722
2,705,227
2,824,089
2,843,577
2,908,670
Young et a1. ___________ __ Oct. 6, 1953
Stamatoff ___________ _.. Mar. 29, 1955
Peters et a1. __________ __ Feb. 18, 1958
Friedlander et a1 _______ __ July 15, 1958
Hagemeyer et a1 _______ __ Oct. 13, 1959
2,921,048
Bell et al ______________ __ J an. 12, 1960
5. The composition of claim 1 in which the isotactic 15
polyropylene has an average molecular weight of from
2,925,400
Tholstrup et a1 ________ __ Feb. 16, 1960
2,939,860
Schramm ______________ __ June 7, 1960
about 100,000 to 1,500,000 Staudinger.
2,957,849
Kennedy _____________ __ Oct. 25, 1960
2 to 5 minutes.
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