Note: Descriptions are shown in the official language in which they were submitted.
; 1084~Z
!
This invention relates to the use of sulfur containing
phenolic compounds as antioxidants for polymers, both satur-
ated and unsaturated, vulcanized and unvulcanized. It also
relates to a process of preparing said compounds.
Those concerned with the stabilization of polymers
against oxidative degradation are constantly searching for
new and effective antioxidants. In any application it is
desirable that the antioxidant have a reduced tendency to
; discolour the polymer either before or after the polymer
has been subjected to aging conditions particularly of the
high temperature type. Resistance to oxidation and
discolouration are extremely important in many applications
in which polypropylene is used.
Those skilled in the art have used phenolic com-
pounds on occasion to provide antioxidant protection. Some
have used sulfur containing bisphenols, e.g., see U.S. Patents
, 3,459,704; 3,679,744; 3,637,808 and Canadian Patent 812,262.
It is an object of an aspect of the present invention
to provide phenolic antioxidants for the protection of
polymers against oxidative degradation. An object of an
aspect is to provide polymers stabilized against oxidative
degradation. An object of an aspect is to provide a
process of preparing said antioxidants. Other objects of
other aspects ~ill become apparent as the description proceeds.
In accordance with one aspect of this invention
there is provided as antioxidants for diene rubbers
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phenolic compounds having the following structural formula:
AXAl
;~ wherein A and Al are selected from structures I and II as
S follows:
R R2 R R5R6
, HO_~ (CH2)x(CH)y(C)zY'COCHCH~ (I)
R R4
~R ~ ,R14 ,R5 ,R6
~HO ~ C~- C - (CH ~ ) mY ' COCHCH - ( II )
; R 2
and X is R8
., .,j .
-SR (YR ) nlS
wherein Y' is -O- or -NH- and wherein R and Rl are
selected from the group consisting of tertiary alkyl radicals
having 4 to 8 carbon atoms and cycloalkyl radicals having 5
.~ to 12 carbon atoms, R2 , R3 , R4 , R5 , R6 and ~8 are
selected fror,l the group consisting of hydrogen and alkyl
radicals having from 1 to 4 carbon atoms, R7 iS selected from
the group consisting of alkylene radicals having 2 to 6
carbon atoms, cycloalkylene radicals having 5 to 12 carbon
atoms and alkyl cycloalkylene radicals having the following
structural formula
-Rll- Rl0_[R12~
n
- wherein R9 is an alkylene radical having 2 to 6 carbon atoms,
Y is selected from the group consisting of -O-, -S-,
''
.: - 2 -
- 1~84~6Z
phenylene and
-CoR130c-
,, " 11
O O
and wherein nl is O or 1, x+y+z is O or a whole n~ber from
2 to 12, R10 is a cycloalkylene radical having from 5 to 12
carbon atoms, Rll and R12 are alkylene radic~ls having from
1 to 6 carbon atoms and n2 is 0 or 1, and wherein R13 is an
alkylene radical having from 2 to 6 carbon atoms :~ich can
be substituted or unsubstituted with one or two groups of
the structure O
, . . ,.
./ 10 - OCB
wherein B conforms to structural formula
R8
1~ AS~7-
alkyl radlcals having 1 to ~ carbon atoms and phenyl and m
is O or 1 with the proviso that when Y'is -O-~ m is 1.
Preferably R and Rl are tert.butyl radicals, R2,
R3, R~, R5 and R8 are hydrogen or methyl~ R6 is hydrogen~
R7 and R9 are ethylene, nl is 0~ x is O to 3~ y is O or 1
z is O or 1, and x+y+z is 0, 2 or 3. Preferably R10 is
cyclohexyl, Rll is ethylene and n2 is 0.
: The following compounds illustrate,but do not
limit,the compounds of the present invention.
4~2
Compound
Number
I bis(3,5-di-t-butyl-4-hydroxyphenyl) ~,10-dithia-7-
oxatridecanedioate
II bis(3,5-di-t-butyl-~-hydroxyphenyl) 4,7,10-tri-
thiatridecanedioate
III bist2,2-dimethyl-3-(3,5-di-t-butyl-~-hydroxy-
phenyl)propyl~ 4,7,10-trithia-2,12-dimethyl-
tridecanedioate
.:: 10 IV bis[2~2-dimethyl-3-(3~5-di-t-butyl-~-hydroxy-
phenyl)propyl] ~,10-dithia-7-oxa-2,12-dimethyl-
- tridecanedioate
V N,N'-bistl,l-dimethyl-2-(3,5-di-t-butyl-4-hydroxy-
phenyl)ethyl]-4,10-dithia-7-oxatridecanediam de
VI N~N'-bistl,l-dimethyl-2-(3,5-di-t-butyl-~-hydroxy-
phenyl)ethyl]-~7-dithia-5-me~hyldecanediamide
VII bis(3,5-di-t-butyl-4-hydroxyphenyl) ~,7-dithia-
2,9-dimethyldecanedioate
VIII bis(3,5-di-t-but-~1-4-hydroxyphenyl) 4~7-dithia-
. 20 2,5,9-trimethyldecanedioate
:. IX bist~-~3,5-di-t-butyl-4-hydroxyphenyl)-2-butyl]
. ~,7 10-trithia-2,12-dimethyltridecanedioate
X bis[4-~3,5-di-t-butyl-~-hydroxyphenyl)-2-butyl]
~7-dithia-2~9-dimethyldec-anedioate
25 XI bist4-(3~5-di-t-butyl-~-hydroxyphenyl)-2-butyl]
~7-dithiadecanedioate
XII bis[2,2-dimethyl-3(3,5-di-t-butyl-~-hydroxyphenyl)
propyl] ~,7-dithia-2,9-dimethyldeca~edioate
XIII bis[2,2-dimethyl-3(3,5-di-t-butyl-4-hydroxyphenyl)
propyl] 4~7-dithiadecanedioate
XIV bis~2,2-bis(3,5-di-t-butyl-4-hydroxybenzyl)propyl~
4,7-dithiadecanedioate
XV bis[2,2-bis(3,5-di-t-butyl-4-hydroxybenzyl)butyl]
~,7-dithiadecanedioate
XVI l,l,l-tristmethylene 6-(3,5-di-t-butyl-4-hydroxy-
phenoxycarbonyl)-~-thiahexanoate] propane
. XVII l,l~l-tris[methylene 6-(3-(3~5-di-t-butyl-~-
;l hydroxyphenyl)-2,2-dimethyl propoxycarbo~yl)-
:~ 4-thiahexanoate] propane
~ XVIII tetrakis[methylene 6-(3,5-di-t-butyl-~-hydroxy-
phenoxycarbonyl)-~-thiahexanoate] methane
XIX tetrakis[methylene 6-(3-(3,5-di-t-butyl-4-hydroxy-
phenyl)-2,2-dimethyl propoxycarbonyl)-~-
thiahexanoate3 methane
All of the above compounds I to IX have been
- prepared. Compounds I to IV are the compounds of worXing
; examples 1 to ~
. .
Additional compounds ~Jhich illustrate but do not
limit the compounds o~ the present invention are as
~oll~ws.
--4--
:i0840~2
.
N,N'-bis(3,5-di-t-butyl-4-hydroxyphenyl)~,9-
dithiadodecanediamide
bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)prop-rl~
~,3'-(1,5-cyclooctanedithio)dipropionate
bis( 3, 5- di-t-butyl-4-~ydroxyphenyl) 3,3'-[~ 5 ~-
tricyclo(5.2.1.02~ )decanedithio3dipropionate
bis[2-( 3, 5-di-t-butyl-4-hydroxyphenyl)ethyl] 6,6'-
(1,~-~henylene)bis(4-thiahexanoate)
N,N'-bisll-methyl-2-(3,5-di-t-butyl-4-hydroxyphenyl)
ethyl~-~,7-dithia-3,8-dimethyldecanediamide
1,6-hexanediyl bis[6-(3~5-di-t-butyl-4-hydroxyphenoxy-
carbonyl)-4-thiahexanoate3
bist3,5-bis(l,l-dimethylpropyl)-4-hydroxyphenyl]
4~7-dithiadecanedioate
bis[2,2-bis(3,5-di-t-butyl-4-hydroxybenzyl)-2-
phenylethyl]-4,7-dithiadecanedioate
~- N,N'-bis~l,1-bis(3,5-di-t-butyl-4-hydro~ybenzyl)ethyl]-
4,7-dithiadecanediamide
The compounds of this invention can be prepared
by the base catalyzed addition of a polymercaptan to a 3,5-
di tert.alkyl-4-hydroxyphenylal~yl ester or amide of an
a-~ unsaturated carboxylic acid. The reaction is no~mally
carried out using an inert solvent at a temperature ranging
from room temperature to the boiling point of the solvent.
Their method of preparation is not critical to their use as
antioxidants.
The following examples illustrate the preparation
of the antioxidants of the present invention by the process
of the present invention and are not intended to be limiting.
ExamPle 1
Bis(375-di-tert.butyl-4-hydroxyphenyl) 4,10-~it~ia-7-oxatri-
decanedioate (R~R'=tert.butyl; x,y,z=0; R7,R~,R~--X;
R7 R9--C2H4: Y=O; n'=1)
To a solution of 11 grams of 3,5-di-tert.butyl-4-
hydroxyphenyl acrylate and 2.74 grams of 2-mercaptoethyl
ether in 75 milliliters of ethanol was added 1 milliliter of
trieth~ylamine. The temperature rose from 260 C. to 31 C.
over a period of several minutes and the mixture was
stirred for several hours before being poured into water.
--5--
:'
10841~2
The viscous oil ~rhich precipitated ~ras separated by ex-
traction ~rith benzene. The benzene ~as evaporated leaving
13 grams of a ~iscous yellow oil.
Exam~le 2
When 3.1 grams of 2-mercaptoethyl sulfide were
substituted for the 2-mercaptoethyl ether in Example 1,
there was obtained 14 grams of bis(3~5-di-tert.butyl-4-
hydroxyphenyl) 4,7,10-trithiatridecanedioate; also a
viscous oil. (R,R'=tert.butyl; x,y,z=0; R5,R6,R8=~;
R7,R9=C2H~; Y=S; n'=l)
E~amPle '.~
Bist2,2-dimethyl-3-(3~5-di tert.butyl-~-hydro~yphenyl)
~,7~10-trithia-2~12-dlmethyltridecanedioate
! To a solution o~ 18 grams of 2,2-dimethyl-3-
(3~5-di tert.butyl-~-hydroxyphenyl)propyl methacrylate and
3.85 grams of 2-mercaptoethyl sulfide in 75 milliliters of
ethanol was added a solution of 1 gram of potassium hydrox-
ide in 10 milliliters of ethanol. The temperat~re rose
from 2~ C. to 32 C. over a period of several minutes and
the reaction mixture was stirred for 3 hours before being
poured into water. The viscous oil ~hich precipitated was
separated by extraction with hexane and the extract was
evaporated leaving 17 grams of a viscous oil which slowly
crystallized on standing.
Example ~
e substitution of 3.~6 grams of 2-mercaptoethyl
ether for the 2-mercaptoethyl sulfide in Example 3 yielded
19.5 grams of bis[2~2-dimethyl-3-(3,5-di-tert.butyl-~-
-6-
84~;Z
: ,.
hydroxyphenyl)propyl] 4710-dithia-7-oxa-2,12-dimethyltri-
decanedioate. (R,R'= tert.butyl; x=2; y=0; z=l; R3, R4,
R5=CH3; R6, R8=H; R7,R9=C2H4; Y=0; n'=l)
Example ~
A mixture of 30 grams of sodium hydroxide, 5 grams
of tetrabutylammonium bromide, 60 milliliters of water and
250 milliliters of benzene is heated to 70 C. and to it is
added over a period of 5 hours a solution of 127.5 grams of
3~5-di-t-butyl-4-hydroxybenzyl chloride and 170 5 grams of
propionaldehyde in 125 milliliters of benzene. The reaction
mixture is stirred for an additional 30 minutes at 70 C.
and is then neutralized by the addition of a solution of
50 milliliters of concentrated hydrochloric acid in 100
milliliters of water. The layers are separated and benzene
is removed from the organic layer on a rotary evaporator.
The viscous residue crystallizes on mixing with hexane and
the solid is separated by filtration. There is obtained
67.5 grams of 2,2-bis(3,5-ditert.butyl-4-hydroxybenzyl
propionaldehyde.
The product of the previous reaction is dissolved
in 300 milliliters of ethanol and 2.6 grams of sodium
borohydride is added to the solution over a period of 10
minutes. The reaction mixture is stirred for 3 hours and
excess sodium borohydride is then neutralized by the
addition of 10 milliliters of dilute (3:1) hydrochloric
acid. The mixture is filtered and the filtrate is poured in
into water. An amorphous mass precipitates from which the
water is decanted. The sticky mass is dissolved in
boiling hexaneO The 2,2-bis(3,5-ditert~butyl-~-hydroxy-
':
` -7-
84Q62
benzyl)propanol crystallizes on cooling the solution and
is filtered offO The product weighs 53.4 grams and melts
at 162-164 C.
5D6 grams of acryloyl chloride is added dropwise
to a solution of 2~ 8 grams of 2,2-bis(3,5-ditert.butyl-4-
hydroxybenzyl) propanol and 10 grams of triethylamine in
100 milliliters OI tetrahydrofuranO Temperature during
the addition rises from 250 C0 to 520 C. The reaction
mixture is stirred for 4~ hours and is then poured into
water. The mixture is stirred until the oil which
precipitates has crystallized. The product is filtered
.:
off and allowed to dry. There is obtained 27 grams of
2~2-bis(3,5-ditert.butyl-4-hydroxybenzyl) propyl acrylate
which melts at 175-179 C.
; 15 The product of the previous reaction is dissolved
in 100 millilters of ethanol along with 2.3 grams of
ethanedithi~Land 1 milliliter of a 40S~ solution of benzyl-
trimethylammonium hydroxide in methanol. This mixture is
heated under reflux for 5 hours and is then allowed to
coolO The solid which has precipitated during the heating
period is filtered off. There is obtained 19.3 grams of
~- bis[2,2-bis(3~5-ditert.butyl-4-hydroxybenzyl~propyl]4,7-
dithiadecanedioate which melts at 156-161 C.
The polymers that may be conveniently protected
by the compounds described herein are vulcanized and
~; unvulcanized polymers susceptible to oxygen degradation,
such as natural rubber, balata, gutta percha and synthetic
; polymers, both saturated and unsaturated, iOe, containing
carbon to carbon double bonds Representative exanples of
--8--
i:;
..,
1~84~62
the synthetic polymers used in the practice of this
invention are polychloroprene; homopolymers of a conjugated
1,3-diene such as isoprene and butadiene as well as
copolymers of conjugated 1,3-dienes such as isoprene and
butadiene with up to ~0 percent by weight of at least one
copolymerizable monomer such as styrene and acrylonitrile;
butyl rubber, which is a polymeriz~tion product of a major
proportion of a monoolefin and a minor proportion of a
multiolefin such as butadiene or isoprene; polyurethanes
containing carbon to carbon double bonds; and polymers and
copolymers of monoolefins containing little or not unsatura-
tion, such as polyethylene, polypropylene, ethylene propylene
copolymers and terpolymers of ethylene, propylene and a
nonconjugated diene.
me precise amount of the antioxidant ~Jhich is to
be employed will depend some~nat on the nature of the poly-
~ mer and the severity of the deteriorating conditions to
hich the polymer is to be exposed. In unsaturated polymers
such as those made from conjugated dienes, the amount of
antioxidant necessary is greater than that required by a
saturated polymer such as polyethylene.
Generally the stabilizexs of this invention are
employed in antioxidant amounts from about .0005 part to
about 10 parts by weight per 100 parts by ~Jeight of polymer,
although this will vary with the particular polymer. A
particularly advantageous range is from about .025 part to
about 1.~ parts. The compounds are especially useful for
the stabilization of polyethylene and polypropylene. The
antioxidants of the present invention have a high molecular
~eight ~hi~h makes them less volatile and less easily
_g_
1084~62
,:
ex~racted from the polymer than lower molecular weight
antioxidants.
The antioxidants are effective whether used alone
or in the presence of other compounding ingredients. Rep-
- 5 resentative examples of such ingredients are metal oxides~
reinforcing agents, pigments, fillers, softening agents~
other antioxidants~ plasticizing agents~ curing agents and
the like.
... .
The antioxidants of the present invention can be
added to the polymer in any of the conventional ways, for
example by addition to the latex or solution form of the
polymer or by direct addition to the polymer in solid form
on a mill or in a banbury.
Compounds I, II, and IV to XIX were evaluated
in SBR at the 1.0 part level. Compounds IV to IX and XII
were evaluated in polypropylene. The results are listed
b~low.
Days to Failure
Compound at 140 C. in Hours to Absorb 1~ Oxygen
Number PolyProp~lene at 100 C. in SBR-1006
I -- 494 (~6~)
II -- 523 "
III -- ~~~ ~~~
IV 22 536 (464)
~ 28 ~36 (328)
- VI 30 468 "
VII 91 593 "
VIII ~ 653 ''
X -- 549 (282)
XI -- ~81 '~
XII ~3 701 (328)
XIII -- 43~ (282)
- XIV -- 3~2 (237)
XV -- 371 (237)
' XVI -- 375 (280
XVII -- 371
XVILI -- ~0 "
XIX -- ~38 "
Figure in ( ) is ~or oxygen absorption ~alue for a
butylated, octylated phenolic antio.~idant control.
(
;~; -10-
- \
iO 89UD~2
All of the compounds tested improved the re-
sistance of the polypropylene and SBR to degradation. ~ad
no antioxidant been present, the polypropylene would have
failed in 1 to 2 days, and the S~R would have absorbed
5 1.0% 2 in 5 to 10 hours.
; Any of the phenolic antioxidants described herein
could be used in the previously described working examples
to provide protection for any of the polymers described
herein.
While certain representative embodiments and
details have been shown for the purpose of illustrating the
invention, it ~Jill be apparent to those skilled in this art
that various changes and modifications may be made therein
without departing from the spirit or scope of the invention.
,
.,
.,
v
.
.
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