Note: Descriptions are shown in the official language in which they were submitted.
E'RIOlR ART ~ ~
~____
Kline 3~$897~9 dlsl~lo~e~ polymers eon~aining
relatively low levels o cert~ln N,N'-disub~3tituted
p-phenylenediamine wnlts chemically bound to polymer~
as substituents of acrylic mor!omer unlts present in ther~
which unlt~ have reslstance to aging at e:levated tem-
peratures. Thls resis~anee ls no~ possessed by similar
polymers not conta~lng such ~ubstltuents. Ths age-
re~i~ting func~ions are introduced iDto the polymers by
copolymerization of acrylic monomers conta~ing such
functions wi~h v~nyl or dienic monomers to prepare the
polymer system.
A review ar~icle by Meyer~ Tewksbury and Pierson
in HIGH PûLY~ERS, Vol. XIX, E. M~ Fetles, Ed. 9 Inter- :
science, New York, 1964, Chapter 2, dlscloses the in-
corporation oiE aliphatlc mercaptans into polydi~nes to
varying degrees by many workers and that ~he reactio
involved was addition of ~ ercaptan to a polymeric
double bond. The degrees to which the re~uïtan~ adducted
polymers differed in properties from the polymeric reactants
depended on the degree of lnterac~ion.
- TNE INVENTION -
This lnven~iQn relates to polymer~ ~3elf-
resistan~ to &ging wh~ch contain N~ disubs~i~uted-p- ~:
phenylene~diamîne groups bound to ~he re~pec~lve polymer~
-
by monosulEide linkages~ It also relates to me~hods o~
preparing such compos~ tions by interact-lons o: certain
am~nomercap~ans which are N, N7 -dlstlbstl~u~ed p-phenylene
diamines, each containing a mercap~o alkyl function,
eithe~ with a polymer radical during the course of a
. free-radical polymexi~ation3 or w:Lth a polyroer contalning
at least one ole~ln unit per molecule in a po~t-polymeri~
zation addition reactlon. Aminomercaptans wh:Lch are
useful in the proces~ are d~scussed under the heading
The Aminoa~ercaptans.
It is well known that cer~a~n N~N'-disubstitu~ed
p-phenylene diamine derivati~es, when used at relatively
low weight levels, as addi~ives ~o certain oxidizable oils,
fat~ or polymer~, greatly enhance the resi~tance to aging
or ~co oxidation of ~hese materials~ l~ence9 by iDcorporating
a corr~pound c~ntaining ~uch a diamine ~ubstituen~ into a
polymer by means of a chemical bond 9 one malces ~ueh
polymer intrin~ically resi3tant to aging. Such age resis-
tance cannot be removed from the polymer by extrac~ion,
sublill~ation, decantation, filtratlon or by o~her phy~ical
2V proces~ by which conventional antiox:Ldant additives can
be rem~ved from polymer~.
According to the pxesen~ inven~ion, an amino-
antioxidant functlo~ is ~ncorporated into a polymer at
relatively low levels by interac~ion of relatively low
3~
`3~ ~
lev21s of a non-monoaler~ c amlno-- sub~tl~uted mercaptan
elther (a) as a chaln ~ransfer reagen~ reac~ing bo~h
with monomer and w:l th growlllg polya~er radisals during the
course of a free radlcal polym~rization or (b~ in an
addition process ln wh:Lch ilt reacts with a pr~formed
polymer conta~ing at least vne double bond or (c~ in a
reac~lon wl~h a polydlen~ homopolymer or copol.ymer during
the course of milling and curlng. All such irlteractions
may be carried out e~ther in emulsion, solutiong
lû dlsper~ion, or bulk media.
The pol~ymer composltions prepared by the proce~es
of thls invention are preferable to known siolilar polymer
composit~ons not containing chemlcally bourld ~ge resisters
but protected by conven~ional age~resister~.
Hence polymers con~aining such chemirally
bound age-reslster groups have a di~lnct advantage over
polymers of similar ~ructure bu~ pro~ec~ed only by
admixtuire wiLth conventiosaal age resister compound~.
~he pol~ymers with built-in age-resis~ance are
usually composed of segmers o:E conjugated diene monomers
of 4 to 10 carbon atom~ or non-conjugated cyclic or
acyclic olefln monomers of 2 to 20 carbon a~om~ or vlnyl
monomer~ o 2 to lV carbon atoms.
?,~3,~
Example~s of Ithe products made from the new
polym~rs with bullt~ln age-resi~ter~ inolude mbber goods
such as liners, gaske~, hoses and belts ~ubjscte~ to
eleva~ed temperatures and/or -ln contact with oils or
sslvents, and oam rubber backing~ for carpets subiected
~o dry-cleaning, etc~
The product~ wlth built-in age res~ st~ncP may
be li~uid or elastomerlc solid. They may be ela~itomer~ or
more resinous, depending upon ~he na~ure of ~he mononeer
used and ~he 7l01erular weight, etc., and no lim~ta ~on 1~
placed on the ms~lecular weight. Those which are e~a~tomers
may, when compollnded wi~ch vulcanizing ingredieIl~s; be
vulcanized and used wherever rubber~ are employed. Some
of these may be used as gums 9 when IlOlt vulcanized . Depend-
ing upon ~he nature of the polymer~ it ~ay be u~ed ~r
coatings for wood, fabrlcs, metsl~, ~tc., :Eor c:aulking~,
moldings, etcO
The amount of the age-resi~ting group united
- with the polymer i5 generally comparable to the amount
of conventional an~ioxidant or an~iozonant employed,
being generally between ~.10 and 10 par~, and preferab:Ly
-~ 0. 5 ~o 5 parts per 100 par~:~ of the polymer . Th~ amount
may vary depending upon the particular aminomercap.an9 ~he
nature of ~:he polymer, and the use to be made of the
-
f~ j t~7
produc~. F~r ins~ance, an installatlon in the tropic~s
wlll requlre more than the same installation whlch is
~o be lnstalled in a cold climate.
One process of the present invent~on involve~
a cha~n-transer reac~ion, in which certaln mercap~o-
alkyl derivative~ of N9N'-dlsubstitu~ed-p-phenylene di-
amines wh~ch have antioxidant properties intera~.t with
a polymerizing monomer system to produce polymer~ eon-
talr~ g these dlamino subætituents interlinked with the
polymer through a monosulid~ bondO This is discussed
below under the heading The Ghain Transfer React~on.
The resultan~ polymer has an intrinsic age resistance.
Such polymers may be produced by polymexizlrlg any mono-
mers or mixtures of ~aonomers capable o homopolymerlz-
a~ion, copolymerization or in~erpolymerizat~on by free-
radical mechan~sm in pre~elace of such diamine deri~a-
tive~. Such mODOmerS include con~ugated dlenes coDtain~
ing 4 to 6 or more up to~ for example,-10 carb~n atoms~
and halogen der~va~ives thereof, includi~g bu~adlene-l,
3; 2-ethylbutadiene-1~3; 2,3-dime~hyl-butadlene-1,3;
isoprene; piperylene; 1~3-hexadienes; 1,3-decadienes;
and 2-chlorobutadiene; etc. 9 and vinylic monomers Ln-
cluding s~yrene, alpha methyl styrene~ divinyl benzene9
vinyl chloride, vlnyl acetate, vinyl pyr~dinesg vinyli-
dene chloride, acrylonitrile~ methacrylonltrile~ ethyl :-'
acrylate, methyl methacrylate, aerylic acid,
methacrylic acid, maleic acid, ~6-
- . ~ .
.
ilacl)nlc acid, and maleic anhydride, etc.
Another proc~ss of the present invention ln-
volves another free-radical reaction of a member o~ the
same family of aminomercaptans wi~h polymer substrates
which contain at least one reactable double bond per
polytner moleculeO This is an additi.on reaction in which
the aminomercaptan reacts wi~h this double bond. This is
discussed below under the heading The Free-Radical Addition
Reaction.
Thus, any isotactic~ syndiotactic or atactic
homopolymer or copolymer which contains a double bond
reactable with the operable aminomercaptans can be used
as a substrate in carrying out this addition process.
A third process relates to interaction of any
of the Eoregoing polydiene homo- and co polymers with
said aminomercaptans during the course of mllling and
curing in the presence of rubber ehemicals including
reinforcing agents and pigments, etc~ Because the
reaction takes place during milling and curingl the exact
nature of the reaction is not cLearly evident but a
vulcanized product is obtained which is intrlnsically age-
resistant. This is further discussed under the heading
Milling and Curing Process.
In this process, a small amount of the amlno-
mercaptan is used, such as 0.10 to 5 parts, more or less.
.
3~
The temperature rnay vary wid~ly. If the mi:Lllng is ~on-
duc~ed at a sufficien~ly hiLgh ~:empera~ur~, some or all of
the reac~ion may be completed before curing. The curing
operation will be employed at any usl3al ~empera~ure, and
~he time required wlll depend upon th~ polymer sy~tem,
~he ~em~er~ re and the cwr:Lr3g syst~m.
The s~lnomercaptan~ usefl31 in producing the
a~e-resist:Lng polymf~rs of this invention are defined by
the following ormula;
Rl ~1 3 1 5
dH(C=O)~--C ~f~n--SH
R2 R4 R~ FORMIJLA 1.
which is ~omet~mes referred ~o as ZSH. In thi~ func~ion
R ~ a radlcal of the c~a~s coIlsi~cing of ~a)
phenyl or pher3yl which 1~ substi tuted in .
any one or srlore posl~ions with an alkyl or
alkoxy group of 1 to 4 earboxl atom~ or w:ith a
. radical o:E the formula N 7
in which both 1i~ and E~ may be either an
- alkyl group o:E 1 to 4 carbon a~om8 or hydrogen, ~ :
or ~b) ~ cycloalkyl r~adical havlng from 5 ~o
12 carbon atorns, or ~c) a branched acycllc
group comprising a chain of 1 to 12 oarbon
atomsS, and each carbon m~y be subs~itutP.d wi~h
1 or 2 alkyl g oup~ of 1 'co 3 carbon atorns; ~ :
' r~ t~J
or ~d~ an allcycllc aralk~rl or aryl radioal
haviDg :~r~m 7 to 14 carbon atoms~
m ~ zero or 1
1~13 a ~
R5 and ~6 are each selected from
~he group COll~ Lng o:l~ hydrogen and alkyl
groups o 1 ~o 5 carboD atora~; and may be
th~e ~ame or dlPferen~.
The mltlo~rcap~an may be prepared by various
10 methods. A p phenylene diamlDe substitu~ed at ore nitrogen
atom wi~h ~he de~ired aryl or alicyl subs~l~uen~"
P~C6H4~ may be conver~ed ~o an N-mercap~o alkyl acyl
C6H4 ~C = O~CH2)r~5H by dlrect amldation
with a mercapto ac~d ~uch as ~:hioglyeolic or be~a-mercapto-
proplonic acid~ Illus~ration~ o ~uch preparations are
included as }~ample 1. N-Mercap~oalkyl derivative~ of
similarly ~;ubsti~tJted p~phenylene diamines (as illu~trated
itn Formula 1 where m3zero) may be prepared from the l~ter
by treatment with ethylene sulfid~ csr propylene ~uliEide, ~r,
~n a ItW0-8tep proc~dure lnvolv~ng ~r~atmell~ o an N-substi~
~uted phenylene dlamlr1e ~i~h a ha:Lf mole equiv~len~ o
a slithiLo dialdehyde uch as d, ~' di~:hioi~o~utyraldehyde ~o
- form a dithio diia~ine 1 a procedure described by Ju J~
_g_ . .
.' ~ ' . . .
D'Am~i.co ,1nd W. E~ Dah]., J.Org.Chem. 409 l22~ ~l975~J; and
subsequen~ reduc~ion of the diamine to an aminomercaptan
~ith lithium aluminum hyclrlde i.n refluxi.ng tetrahydrofuran
~cl procedure described by J. L. Corbin and D. E. Work,
J,Org.Chern. l~ 489 (l976)~ or some other reducing system.
Such a procedure is illustrated by Exar~le 3.
The method o:~ preparing the aminomexcaptans use-
Eul in this invention is not cri~ical ~o the prac~ice of
this invention.
lORepresentat.-.ive amino-mercaptans whlch can be
used in the present inven-~ion are listed below and the :~
numbers refer to the numbers in Table I.
No. Name .
.
I N~(4-anilino-phenyl)-~ -mercapto-acetamide ~:
II N-(4-anilino phenyl)-~mercapto-propionamide
N-(4-anlsldino-phenyl)- or N-~4-phenetidino-
pheny~ mercapto acetamide
: V N-(4-anisidino-phenyl) ~ -rnercapto-propionamide
N-(2-toluidino-phenyl) C~-mercapto-acetamide
IV N-(2-toluidino-phenyl) ~ -mercapto-propionarnide
III N (4-toluidino-phenyl)-~mercapto-acetamlde ::
VI N-~4-(~' J ~ - dimethyl~butylamino)-phenyl]- ~-mer-
capto-acetamide ~ :
VII N-~4~ dirnethyl~butylamino~ phenyl]-~ -mer- ~ ~ .
cap~o~propionamide
-10-
3~g~ ~ :
Ncl. Name
N- ~4~ani~idino-phenyl) ~mercaptc- :
propionamlde :
N- ~4~pherletldlno-phenyl~ merS~apto-
pr~pionamide
Another amlno mercaptan which ls descrlhed ln 13xample 3
as comp ound XIV is:
X~ NW(~ ~mercapto-f~ 3~-dimethyl~ethyl)"
N ' ~pheny 1 -p -plheny lene d lami~e
~: 10 E~samples ~E ~iamln~ sub~tr~ e~ suitable for prepara~i~
o:E a~aino-ntercap~:ans useful in thi~ inven~ioll, de~cribed
and referresl to ~r number ln Table II" are:
VIIï M-phenyl-p-phenylellediamine
. X N-2 ' -tolyl-p-phenylen~diaDllne
XITI bi~[~ ~(4~anilinophenyl-irn~o)~., C3.
dime~hyl~ethy~3 disul~iLde
~4 1 -phe~etyl-p-phenylened~ amin~ -
- IX N-4 ' -toly~-p-phenylenedlamine
~0 XI N-4 ' -ani.syl-p-phenylenediam~ne
XII N- ~a ,~ ~ -d~ethyl-butyl)-p-phenylenediamlne
N- (4 ' ~dirnethylamino~phenyl ) -p -phenylea~ -
diamine
The aminomercap~an~ may be used as anti oxidan~s following
conventioDal procedure~.
h ~
Wl~hln ~he family o:f am:Lnosul~lde groups
illustratcd by %S~ group of Formula 1, there i~ a sub~
family of amlno ~roups hav.ing the essential structural
fea~ures of certain diamirles which are u~Pd oommercial:ly
as antiozonants. These are those am:ino group~ in which
at least one of the nitrogen atoms of ~he para-phenylene-
dlamine ~sroup is substitutecl by an alkyl group through
a ~econdary or tertlary carbon atom ~a condltlon o~
Formula 1 in wh~ch m = O, and at least either R3 or R~$,
1(3 is an alkyl group ra~ er than hydrogerl,) and the other
nltrogen atom o:f thi s d~ amine group 18 a*tached either
~o an alkyl, a phenyl, or substl~u~ed phenyl group,
through a ~econdary or t:ertiary carbon atom ~a carbon
:~ atom havirlg no more t:han one hydrogerl atom sub~tituent).
This ub--family of aminosulfide group~ provides polymers :::
~- to which these group~ are attached wi~h an appreciable
d~gree o re~istance o ozone cracking in addition to
an enhanced resistance to at~ack by oth~r :Eorms of oxygen~ :
According to one reac~ion~ a mercaptoalkyl
derivative o an N~ N' -disubstitu~ed diamlne is ~hemically
incorporated lnto the pe)lymer by a monosllliEide bond by
means of a chain ltransfer reac~ion~, The sl~eps of the
reac~ion are repre~ented by the following equations:
3~
M ~b~ IM- E~U~TION 1
IM- + nM ~ IM"+; ~ P~ ~Q~1A~eION 2
P~ -t ZSH ~ P~, H -~ ZS~ EQUATION 3
ZS + M ~ ~s~ QUATION 4
ZS~ M 4~ ZS~Sq ~ PyEQU~TII:)N 5
Py + 2.SH ~ PyH ~ ZS~ ~Q17AT~ON 6
In the~e equations:
T~ ~ the ac~:~v~ing ~nltia~or radlcal
M ~ ~he reactlng wlonomer ~as defined
e~rlier or the chaln ~ranser proces~)
n and q ~ numbers o:f molecules o.~ monon~r
reacti~g wlth initial monomer radlcal
P~ represents th~ relatively small number of
polymer radical~ generated initiall~r
Py- represents the rnajority o polymer raelic~
formed ~ wh~ch are chemically bonded ~o
~D a~o group through a ~ulfide linka~e
ZS~ ~ a member of ~he family of amino~
mercaptans used; ~ which the s~ruc~ure
~-: 20 æs is de ined in fur~her detail by the
am~osul;f:Lde group illus~rated :Ln
Formu:La l.
-13- :
. :
: :
An illustration of such a chain transfer
reaction clS a mode of incorpora~lon of an aralkyl sul1de
group into polymer.s is given in the study of the inter- '
action of 2-mercaptomethyl naphthalene with a polystyren2
radical, which is to be Eoun~ in an ar~i.cle oE Plerson~
Costanza and Weinstein in J. POLYMER SCIENCE, 17, 2~1,
~1~55).
In the use of the chaln transfer method of
chemlcal incorporation of amino an~ioxidant functions into
polymers, one or more monomers known to polymeri~e under
,~ free radical conditions may be polymerized ln the presence
of a low level of one o~ the amlno mercaptans useful in
this lnventlon. The polymerizations Inay be carried out in ~ '
,emulsion, suspension~ `bulk or solut~on type systems, Some
adjustments in the polymerization recipe and¦or conditions
are necessary to assure that a satisfactory ra~e of polymer
formatlon and a desirable polymer molecular weight level ~`:
are achieved. Among the parameters critical to achievement
of,the process are the level o~ aminomercaptan charge,
which may have an effect on the degree of lnhibitlon of
polymerization as well as a very deflnite effect both on
the level of age~resistor function incorporated into the
, polymer and on the average molecular weight of the resul
tant polymerO Other adjustments which may be required in
' order to achieve such goals are the choice o a free
.~ -1
3~ d
radical initlator system which doe~ not pre oxidize the
aminomercaptan lnto a substance which greatly retard~
or prevents polymer:i zat l~n, and ~he po~s:1 ble u~e of a
solven~ or diluent addit~Ye including u~e of a comonomer
chQsen to a~slJre ~he so~LI3bilit:y of ~he amino me:rcap~:an in
the polymer:Lzation sy~tem. In em~llsion systems ~ some
solven~s su-~h as pyridine or toluel3eg or small amoun~s of
such comonolllers as styrene, acrylonitrile or acrylic e~ters
can be used to advantage :or the latter purpo~.
Examples of free~radlc~l lni~ia~or sys~ems
useful in the practlce Df the chain transfer process in-
clude those kncwn as "redox" ~ys~ems. An example is thosa
inltiators which employ a comblnation ~uch as a chelated
ferrous sal~, sodium ormaldehyde sulfoxylate and an
organic hydroperoxide such as cumene or para-meal~hane
hydroperoxide,
Thermally dissof iative compounds m~r also ~e
used as polymerization in~lators for this process~ Tho~e
dissociative in~t~a~ors which are not capable of oxidizing
the amlnomercaptan~, such as azo compounds, for exan~ple,
c,~, d '-azobls-~ obu~yrs~nitrile and ~ " ~ '-azobis- .
( ~ ~ dimethyl-valeroni~:rile)" are~ preferable over
disRocla~ive peroxy ini~la~or~, such a~ ammonium persul-
;. fate or tertiarg bu~ylperoxy isobu~yxa~e whiL~h are les~
-efective .
T~le reaction may be carried out in solution.
If an emulsifier is employed, a suit~ble emulsi~ier is
selccted. Other compo~ents such as buEfers (to control the
pH) may be used. Suspending agents are used, if desired.
These and other components such as colorin~ agents, etc.
may be used in de 5 ired amoun t 5 ~
The te~perature will depend upon the initi& or
used, etc. In the "xedox" system, the temperature will
generally ~ary between 0 and 50C~ Using thermally dis~
sociative initiators~ the temperature will vary from
about 30 to 100 or 120Co ~ more or less, depen~ing upon
~he half life of the initiator and the particular monomer
system.
2. T~E FKEE RADICAL ADDI'rION REACTION
This procedure is an addition reaction for
introducing the age resisting group into a polymer. It
involves the interaction of an arylamino alkyl mercaptan
with a polymer containing at least one vinylic double bond
or internal double bond per polymer molecule. This inter-
action is similar to tlle well-known addition of methyl
mercaptan molecules to the olefin units of polydienes to
form wholly or partially saturated addition products which
contain methyl sulflde substituents. (5ee the article by
Meyer 9 Tewksbury and Pierson in HIGH POLY*ERS, Vol. XIX
E~ M. Fettes, Edo ~ Interscience, New York, 19~4, Chapter 2,
, -16~
'
startir~g on page L33. There are foreign pat~nts relative
~o Lhe reaction.?
The ste-reochemical nature of polymers useful in
this addition reaction may vary widely and they include
polymers made from monomers containing 2 to 20 carbon atoms.
ThPy include isotactic, syndiotactic cmd atactic pol~diene
homopolymers and copolymers wi~h otber conjugated or non--
conjugated dienes or vinyl monomers. The method o pre-
paration of such polymers is not lmporkant as long as the
reactability of at least one olefin unit per polymer molecule
is maintained. Polymers applicable inclucle naturally
occurring polydienes such as natural rubber, gutta percha,
~alata as well as those prepared synthetically from monomers.
Preparat:ion of such polymer may be initiated thermally, by
radiation or by a variety of catalysts including free-
radical initiation systems or cationic, anionic or co-
or~ina~ion complex ca~alysts including the Ziegler-Natta
type.
Included among the polymeric substrates operative
in this process are Eree-radical polymers prepared from the
same monomers or mixtures of monomers which can be used in
the previously described chaln-transfer process as long as
Lhe resultant polymers contain at least one reactable olefin
unit per polymer moleculeO Also included are polymers of
ethylene, propylene or isobutylene contalning small
-17-
:
;lmo~lnts of~ se~,mers of conjugated or non-conjugated acyclic
)r cyclic clienes or polyolefins including isoprene, buta-
diene-1,3; l-norbornene, and 1,5-cycl.ooctadiene.
Included among operative polymeric substrates
prepared by non-Eree radical techni.ques are cis ancl ~rans
: forms of 1,2-polybutadiene or 194-polybutadiene as well as
syndiotactic or atac~ic homopolymers or copolymers prepared ~:
from butadiene-1,3; cis and trans -forms of 3,4 polyisoprene
or 1~4-polyisoprene as well as syndiotactic or atactic
:~ 10 homopolymers or copolymers prepared rom isoprene; analogous
preparable homopolymers or copolymers o 2-ethyl-butadiene-
1,3; piperylene; ~,3-dimethyl-butadiene; 2-chloro-butadiene-
; 1~3; or 1,3-hexadienes.
Other polymers which may be used as substrates
. include those prepared by metathesis reactions of cyclo
olefins~ cyclo-diolefinsJ bicyclo-monoolefins and bicyclo- `
: dlolefins, mixtures of these withCl -olefins or copolymers of
these withC~ -olefin~s, or norbornene. By the metathesis
reaction is meant a polymerization in which the sub-
stituents on the olefin carbon atoms of olle monomer
molecule are interchanged with those o another monomer
moIecule. Polymers so prepared include polypentenylene,
polyoctenylene, or polyoctadlenylene.
Polymers prepared by ring opening reactions
of certain cyclic olefins such as norbornene by a non~
: metathesis catalyst such as a cationic or Ziegler-Natta
- 1 8r
~ ~';"~ 7
type catalyst rnay also be used as substrates for this
process.
In the interaction of an amlnomercap-tan wlth a
double bond already present in a polymer, this in~erac~lon
may be carried out in various ways. The polymeric sub-
strate may be dispersecl in an emu:Lsion, suspensiorl or
solution. The addition reaction is catalyzed by free-
radical initiators, either of the thermally dlssociated
~ype or the "redox" type, preferably the former, ancl
including azo compounds such as bis-azoisobutyronitr~le
and hydroperoxides such as cumene hydroperoxide and p-
rnenthane hydroperoxlde. Temperatures necessary for
effective additions of the a~inomercaptans of this in- -
vention to polymeric substrates are those necessary for
continuous dissociation of the particular catalyst used,
and vary from about Q C. to about 100 C. The time of
reaction required depends upon many factors including
the catalyst used, its~co~centratipn, the level of mer-
captan addition required and Eor the case of additiorl to
s~ereospecific polydienes, the acceptable clegree of
isomerization of polymer configuration.
In the adclition reaction the level of amino-
mercaptan charged may be from 0.1 to 10.0 parts or
preferably 0.5 to 5 parts per hundred parts of polymer
(p.h.p.), and the level of catalyst~ if thermally dis-
sociative3 may be from 0.05 to 59 and preferably Q.05
J
to 1.0 p.h.p. The reactlon temp~rature, using a thermally
dissociative catalyst, may be 20 to 120 C. 3 and is prefer-
ably 30~ to 80 C. The polymer system should be free of
appreciable levels of reactable olefinlc monomers and of
free~ra~ical inhibitors in order to ob~ain a desired level
of mercap~an addition in reasonable time. Such reactions
can be carried ou~ in emuls~on~ suspen~ion or solu~ion media.
3. THE MILLING AND CURING PROCESS
In this process~ the aminomercaptan ls added to
a millable elastomeric diene homopolymer or copolymer on a
rubbPr mill, for example a Banbury, in presence of
chernical addltives used conventionally for curing or vul-
canizlng rubber, ln the presence of air and at conventlonal
rubber milling temperatures, in the presen~e or absence of
reinforcing pigments. Su~h rubber stock is then cured in
an oven or press at a temperature normally used in the art
for production of a vulcanizate, as for example, between
250 F. and 350 F.
Representative polymers and copolym~rs useful in
the process include polybutadiene~ polyisoprene, isoprene-
styrene, butadiene-styrene, isoprene-acrylonitrile, buta-
` diene-acrylonitrile (referred to herein~ as elastomers)
ln which a major portion ls butadiene or isoprene. The
'
.
vulcanizate when extracted with a solvent such as acetone
or methyl ethyl ketone in order to free i~ of non rubber
additives, has a resls~anoe to oxidation or aging very
much greater than that of a vulcanizate which has been
prepared ln the presence o:~ a conveTltional an~ioxidant,
suc.h as 2,6-di-t butyl-p-cresol which has been removed
from the vulcanl~ate by extraction. Ia~orporatlon
of age-resistor functions by this pro~ess ls illustrated
by Example 11~ It is therefore evident that th~ amino-
10 mercaptan used is incorporated into such a polymervulcanizate dur~ng the combined milling/cur~ng process.
AG -R15ISTA~T ~OI~MrR5
The age-resistant polymers o~ this invention
obtained by the several processes described may be de~ined
by the formula ZSP in which ZS is the aminosulfide group
of Formula 1, namely3
l ~ 15
RNH ~ NH(C~O)m--C -- (C)2~ _ S
R2 R4 R~
defined above, and P, whieh has been removed, represents the
polymeric portion of the age-resistant polymers referred to :~
herein~ Thus~ the age-resistant polymers may be represented
by ~he ormula
Rl tR3 ~5
RNH ~ NH(CaO)m--C --(C) --SP
R2 R~ R6
-Zl
Examples of the preparation of age-re~ist nt polymers
by ~he chain-tran~fer reactior; are Examples 4,5,6 and 7.
Examples of the preparation o age-re~istant
polymer~ by ~he addition reac~ion are Examples 8 and gO
Example 10 i~ lustrates the incorporation o:f age-
resi~tant aminosulfide group~ into the polymers by milliDg
and curing.
Example ll illustrates the use of a~lnomereapt:ans
of ~his invention as conventional age resl~ters~
Examples of the preparation o some of the amino-
mercaptans useful ~n ~h~s inven~ionD ~lld intermediates used
:~ . ln their preparation, are illustrated by Exa~ple 1, 2 and 3.
EXAMPLE 1
N- (4-ANILINO rPHENYL~ ME~AP~'O--
PROPIONAMII)E
, .
- A mixture of 1804 gram~ of N-phenyl-p-pheDylene
diamine, 1006 gram~ o ~k~ mercaptoprop:ioTlic acid and 120
`` milllliters of xylene (technical grade) was heated to
reflux ~about 140C . ~ under nitrogen atmosphere " with
stirring~ A 1.6 milliliter quantity of water ~90~ of theory)
was removed from ~his mixture by a2~0trQpic dl~illation
~hrough a ~7igrsux column wlth the ald of a Dean-Stark ~rap,
durlng a 13-hour period. A ~olid produc~ was isoïated in
18. 7 gram~ quantity from the reaction mixture by coollng
-22 -
~ 3~
the latter, pouring into hexane, collecting the resultant
crystalline product: by ~iltr~tion~ washing the crwshed
crystalllne product wlth more hexane and evapor~ting to
dryness. The product was recry~allized from hot toluene
to 17.6 grams (64.5%) of white platelets melting at 98.3-
9~.5C. The resultant new compound, N-(4-anilino~phellyl)-
beta mercaptoproplonamide, sometimes re:erred to hereater
as MPDA, had mereaptan as~y of 9308~/o of ~heoretical, on ;~he
basis of a potentiometric titrat~on with an i90p~0pyl
alcohol solution of silver nitrate~ ollowing a method
described by R. M. Pierson, A. J. Costanza and A. H.
Weins ein, J. Polymer Sci., 17, 234 (1955).
In a manner slmilar to that describ~d above,
a series oiE aminomercaptaDs were prepared by u~e of the
appropria~e diamine and mercapto-acld substra~e~. They
are characterized in Table I. Those product~ wh~ch did
not crystallize readily were freed of mercapto-acid
substrate by extracting their benzene solutlons with
aqueous sodium carbvnate~ and then wi~h water before
isolating.
'
~,
-~7Z- '
1 O ~ `D 09
~ ~:; oo ~ ~
^ :~ ~ l~ ~
~ ~ ~ ~l
o c~
~ ~1 o c~ ~ os
z ~
~ c~
E~
ly;
t~3
~ ~ o~
::l u . ~ .
u~
u~
~ ~ O ~
a: O ~ o~
<~
. . ~ E~ ~ ~ u~ ~ o
~il ¢, 1 H u~
, ~ ~ ~ ~ O
a~ ~ 3 P~ ~I F~IS
O J~
~ ~ ) O ~ 7
e~ 1~ 1 v ~,
~ U~ ~ ~ ~ ~ pq
X
~7
O
~ ~ ll
~ C~ ~C ~
Z; ~ ~
E~ ~ 01
O
æ P~~ ~ ~ ~ ~ ~ ~ ,,
~ P~ o o
:
~ ~ ~ o o~
H H
O H ~ ~ H ~1 ~
æ ~ ~ w H ;~
3~
EXAMPLF. 2
ALK~ OR ~YL-~UP~STITUTED-p-
PHENYLENE _LAMINE SUBSTRATES
The diamine substra~es used ~or prepara~i.on of
~he aminomerc~ptans of Table I and ~he aminomercaptan ~IV,
whose preparation is described in Example 3, are char~
~cterized in Table II. Referring to ~lle examples of -~
T~ble II, they were either ~vailable as the free amine
(VIII) or i~s hydrochloride ~XI~. Compounds IX and X
were prepared from p-nitrochlorobenzene and the appro
priate toluidine according to a method described by R~ H.
Kline, RUBBER CHEM. TE~HNOL. 46, 96 (1973). Compound
XII was prepared by reductive alkylation o~ p-amino-
acetanilide wi-th methyl isobu~l ketone according to a
general procedure discu:ssed by Morris Freifelder in
PRACTI~A~ CATALYTIC HYDROGENATION, Wiley-Interscience,
.
New York, 1971, ~h 17, page 346.
TA~LE II
DIAMIN SUBSTRATES
NO. STRUCTURE MELTING USED FOR PREPARA
POINT, CO TION OF AMINO- ~ :
RNH Nm2 MERCAPTAN NUMæER:
in which R-
VIII Phenyl 76-77 I~ II, XIV
IX p-Tolyl 115~116 III
X o-Tolyl 58.5 IV
XI p-Anisyl 102-103 V
XII 1,3-Dimethyl-
butyl 43-44 VI, VII ~ :
~25-
.: ; ' ;;
~: .
EXAMPIE 3
N-~BETA-MF.~CAPTO-BETA~BETA-DIMETHYL-ETII~L),
N'-P}IENYL~PARA-PHENYLENEDIAMINE _
An intermediate compound; bis-[beta-(4-anilino-
phenyl-imlno)-alpha,alpha-dimethylethyl~ disulfide was
first preparecl as follows:
Following a procedure described for preparation ~ .
by J. J. D'Amico and W, E Dahl, J. Org~Chem., 40 1224
~].975)~c~ -dithiobis-isobutyraldehyde, which was freshly
prepared as described from isobutyraldehyde and sulfur
monochloride, were interacted with two mole equivalents of
N-phenyl-p-phenylenediamine (VIII), at ambient temperature,
in methanol solventO The product~ obtained in 89 per
cent yield~ ~rom a water-washed ben~ene extract o the
reaction mixture wa~s a dark-brown uncrystallizable semi- - :
solid fora~ of bis-[beta-(4-anilopllenyl-amino)-alpha,
alpha-dimethylethyl] disulfide.
Thls diamino clisulfide was reduced to a mercaptan
as follows: A solution of 39.2 grams of compound (prepared
as above) in 150 milliliters of anhydrous tetrahydrofuran
was added dropwise, with stirring, under i.nert atmosphere,
to a re.~luxing solution o~ 5.0 grams of lithlum aluminum
hydride in 200 more mllliliters of the same solvent;
over a 4~-min-lte period. The reaction mixture was per-
mitted to reflux ~or several more hours. The conditions
used for this reaction and the subsequent product work-up
-2~-
.
' 3'~,A ;i~
a:re 1.n acoordance wi-th conditions described for preparation
. o.~ analogous compounds by Corbin and Work, J.Org. Chem.
41, 4&9 (1976). The excess LiAlHIIwas decomposed wi-th
aqueous sodlum potassium -tar-tra-te, and the produc-t isolated .
from a wa-ter-washed die-thyl e-ther extrac-t by vacuum
evaporation. In this rnanner, 37~2 grams of a -th:ick
dark~bro~ syrup, con-taining 47 percen~t of mercaptan,
namely, N-~be-ta-mercap-to-be-ta, beta-dime-thyl-ethyl), N'-
phenyl-para-phenylenediamine, Compound XIV of Table II,
having the -theoretical molecular weight o~ 272, was
isolated.
EXAMPLR 4
,~ INCORPORATION OF AMINOMERCAPTANS INTO
POLYSTYRENE VIA CHAIN TRANSFER R ACTI0N
In two separa-te experiments, 1.00 par-t by weigh-t
of Compounds I or II of Table I, corrected ~or active
mercaptan conten-t, was ch.arged into vials each containing
100 parts of styrene, O.10 par-t OL bis-azoisobutyron,icrile
and 5.0 parts o~ pyridine. In a -third vial~ the same
O proportions of' all ingredients except aminomercaptan were
charged. The vials were sealed under ni-trogen atmosphere
and tumbled for 16 hours in a wa-ter bath at 50C. Low
conversion of polys-tyren,e samples were isola-ted from each
o~ -the -three solutions by coagula-ting into isopropyl .~,
alcohol.
-27- :
: : :
~ 31~
On the basis of inherent viscosity determinations
made on benzene solutions ~f driecl polystyrene samples~
the number av~rage molecular weights were determined for
each sample, using an ~quation developed by F ~. Mayo,
J.Am.Chem.Soc. 65a 2324 (1943~o
In this way, i-t was determined that polyrner made
in the presence o~ Compound IL (MPDA) had a molecular weight
of 17,lOO as compared with a value of 266,000 for the con~
trol polymer. By subs~ituting these molecular weight values
: lO into an equa~ion developed by the cited author, a chain
: transfer constant (T~Co)~ representing a ratio of reactivity
of Compound II over that o~ a styrene monomer molecule wi~h
a polystyrene radical, was calculated. The ~act that the
T.C~ value or Compound II at 50C. obtained in this manner
wa~ an appreciable value, namely ~.40, indicated that
Compound II had reacted appreciably with the polymer by
means o an incorporating mechanism. By slmilar means, it
~ . was shown that Compound I ~MAD~), with a T.C. value of
; 0.273 had an appreciable, if somewhat lesser, ~endency to
~- 20 ineorporate into polystyrene.
EXAMPLE 5
INCnRPORATION OF MPDA I~TO ISOPRENE/STYRENE
: A series o:E emulsion copolymeri~ations A to
E were carried out in four-ounce screw~cap b~ttles using
~` 20.0 gr~ms mon~mer charges and containing the following
-28-
ingredients in commo~l~ all lis~ed in parts per hundred of
monomer:
Isoprene - 75.0
Styrene ~ 25.0
Pyridine - 5.00
Potassium
stearate - S.OO
Distilled
water -200
Variable ingredients were also charged into these
bottles, as lndicated in Table III on a parts per hundred
o monomer basls. Converslon levels o~tained, after the
bottles were swept with nitrogen, sealed and tumbled or
17 hours in a water hath at the prescribed te~peratures9
are also recorded in this table.
TABLE III
VARIABLES A B C D E
Ammonium persulfate - 0.~0. 0.40 - -
; Azobis-isobutyronitrile 0.40 - - 0.40 0.40
MPDAa - 2.00 2.00 - 2.00 ::
Reaction temperature, C. 50 - SO 70 70 70
Conversion to polymer, % 76 0 26 97 80
a. On basis of 100% mercaptan activiky.
Efficien~y of incorpor~tion of MPDA into isoprene/
styrene~ olymers _
A series o~ copolymers o~ substantlally 75~/0
of isopxene: 25% styrene were prepared as in Example 5~
recipe D9 with variables indicated in Table IV including
MPDA charge levels. Polymers were coagulated into
isopropyl alcohol3 freed of non-polymeric substances by
repeated extractions with hot isopropyl alcohol, and
-2~-
3f-q 7
vacuum evaporclted.
Leve:ls oE ~-anil:Lnophenyl-carbamyl units in-
corporated i.nto polymers, on a parts per hundred (p,h.r.)
basis, were determined on basis of a coLorometric assay of
the intensity of blue-colored qulnone-imlne chromophore
developed by oxid~tion o~ chloroform solutions of polymer~
wi~h benzoyl peroxide.
Thin films of polymers of known welght of from
:l to 1.5 grams were made by evaporating benzene cements
of polymers on~o tared aluminum sheets having a surface
area of 1500 cm2O These sheets were lnserted into the
chambers of a typical oxygen absorptlon apparatus.
Oxidation resistance ~0~O~ values for these polymers were
determined as the number of hours required for absorpeion
oE 1 per cent by weight of oxygen by a polymer sample from
oxygen atmosphere at a given temperature9 in this case 90C.
: Data relatlng to efficiency of incorporation of
amino groups and to oxidation resistance of these polymers
are also included in Table IV~ Data shows the marked
enhancing effect of incorporated MPDA on polymer oxidation
resistance.
.; .
30 -
TABLE IV
PARTS BY i~EIGHT I.N
P~CIPE VARIAP~LES F G H J K
~_ _ _ _
MPDA 1.00 2.00 3.00 2.00 - :
n-Dodecyl mercaptan - - - 1, 5a
Pyridine 5~- 5,0 5,0 _ 5~0
POLYMERIZATION ~ESULTS:
Conversion, % 87 80 18 94 92
P'z'n time, hrs. at 70Co 17 17 17 17 7
4-Anilinophenyl-carbamyl0,52 0.76 1.06 - -
units incorporated~pOh.r.
Efficiency of ~DA
lncorporation , % 52 38 35
O. R. Values at 90C.92 520 405 500 8.6
a. Added to insure polymer solubllity in benzene.
bo On basis of parts MPDA charged~
EXAMP E 6
INCORPORATION OF OTHER AMINOMERCAPTANS
INTO ISOPRENE/STY~ENE COPOLYMERS B~
~ 20 CHAIN TRANSFER REACTION :~
: Using the general procedure of Example 5, but
substituting for MPDA, 2.00 part qwanti~ies o other
aminomercaptans characteriæed in Table I, and adjusting
for mercaptan activity~ a series of 75.0 isoprene/25.0
styrene mixtures were polymerized or 17 hours at 70 C.
Polymers were isolated, worked up and tested in the manner
indicated in Example 5. Parameters relating to poly-
merization and to polymer characteris~ics are indicated
-31- :
.~ ' '. ., ', ' , ~ ' ' . :
~h'~ 3~
in Table V.
TABIE V
L M N P Q
Aminomercap tan
number (~ee Tab1e I IV V VI VIIXIV~
I or II~
Convers1On, % 5~ 53 7S ~9 99 27
P'z'n timea hrs. 22 1& 21 17 17 16
a~ 70C.
OJROa va1ues at 9O~CD 95 420 515 380 245 2~0
aO Charging on1y loOO pt~ of aminomercaptan,
O.R. 3 Oxidation-Res~stance: Determined as in Examp1e 6.
IPLE 7
INCVRPORA'rION OF AMINOMERCAPTANS I and
II INTO BUTADIE~E COPOL~MERS VIA CHAIN
r _~r_ e~ACTlo~
Butadi~ne mixtures wi~h either acrylonitrile or
methyl methacrylate weighing 20.0 grams each were polymer-
i~ed in four-ounce 6crew~cap bot l~s in presence of 1.60
part amounts of ~minomercaptans as indicated in Table VI~
along wlth control polymers. Rec~pes used contained the
reduction-oxidation ("redox") type ini~ia~or sys~eins
indlcated in Table VI. Also lncluded in this table are
conversion levels of the resul~an~ polymers and ~heir
oxldation resictant values after remvval of non~polymeric
: substances by extraction.
32-
T~BLE VI
PARTS BY WEIGtlT IN. _ _
INGREDIENTS: T U V W X
~l~tadiene ~7.0 67.0 67.0 8~.0 80.0
Acrylonitrile 33 ~ 0 33 . 0 33 0 0 - -
Methyl methacrylate - - - 20.0 20.0
Tetiary dodecyl mercaptan - - 008 - 0.5
MADA (I)a lo~O
MPDA (II)a - 1.60 - 1,60
Potasslum stearate 5.00 5.00 5.00 - -
Trlsodium phosphate 0,20 0.20 0.20
Sodium linear alkyl sulfonate - - - 5.00 5.00
Water 200 200 200 200 200
4 7H2 0.042 0.042 0.042 0.042 0.042
~; Iron chelating agentb 0.17 0.170.17 0.17 0.17
,odium formaldehyde sulfoxylateO.04 0.04 0.04 0.04 0.04
Cumene hydroperoxide 0.24 0~24 0.24 0.24 0.24
Conversion,% 99 9~ 99 61 9~
~Ro values at 100 C., hours 390 385 1 695 5.9
~. Adjusted upward for 100~/o mercaptan activity.
b. Active parts of a 34% aqueous solution of a 90/10
mixture of a tetrasodium salt of ethylenediamlne
tetracetic acld and the~oao~odlum salt of ~,N-di-
(alpha-hydroxyethyl) glycine, sold as 'iVersene Fe III".
-3~-
' ~.
- . ~ .
33~-t. 1~)
The last two lngreclien~s charged lnto each
b)~le were the butadlene and the cumene hydroperoxide.
The bot~les were prechilled to 0C. beEore adding the
butadiene 7 swept free oE air by venting the excess of
this monomer, and eacll was sealed with a ~crew-cap Lined
with self-sealing rubber and Teflon gaskets. The
l!ydroperoxide was then added through the cap by use o
a hypodermic syringe~ The bottles were then tumbled in a
water bath at 10C. for 16 hours. Polymer latices were
coagulated into isopropyl alcohol, and the r~sultant
coagula freed of non-polymeric ma~erial by repeated
- extractions wi~h hot isopropyl alcohol~ The copolymers
were evaporated to dryness in vacuum, and tested ~or
resistance to oxidation as in EXAMPLE 7, cas~ing nitrile
copolymer films from methyl ethyl ketone and the acrylic
es~er copolymer films from benzene. In thls instance 9
the oxidation resistance value determination was done at
100 C.
Results, as indicated in Table VI, show that
the resis~ance to oxidation of butadiene acrylonitrile
copolymers were greatly enhanced relative to a con~rol~
b~ incorporation of antioxidant groups by the use of
either aminomercaptan I (MADA) or II (MPDA) and that
oxidation resistance of a butadlenelmethyl me~hacrylate
copolymer was greatly enhanced over that of a control
~34-
: by simi].ar incorpa~i.on of MPDA.
; EXAMPI.E 8
INCORPORATION OF AMINOMERCAPTANS INTO
POLYBUTADIENE ~ ADDITION IN EMULSION
~ A polybutadiene latex was prepared by polymeriz-
.~ ing butadiene in an 8-o~ncc screw cap bottle for 16 hours
at 50C. using the reclpe lndieated in TABLE VII.
TABLE VII
INGREDIENTS PARTS BY WEIGHT
Butadiene 100
Tertiary dodecyl mercaptan 0.50
K2S28 0.1U
Potassium ~tearate 5.0
: W~ter 200 ~ :
The resultant latex was stripped o res~dual
bu~adiene monomer by gently distillingS under ni~rogen
atmosphere~ until no oaming occurred and a few droplets
of wa~er condensPd~
Two 8~ounce screw-cap bottles were each charged
with 72.7 gram quantities of this latex (23.9% solids)
containing 20,0 grams of rubber. To each was added 0.25
parts of a~obl~-isobutyronitrile per hundred of rubber
~p.h.r.). One was charged with 2,00 parts o MADA, the
other with 2.00 parts of MPDA, both adjusted to 100V/o ~ ~;
mercaptan activity. Bottles were purged with nitrogen,
-35-
" ' :
sealed an~ tumbled for 16 hours in a water bath a~ 50C.
These latices as well as a sample of untreated
polybutadiene latex were coagulated into isopropyl alcohol,
ex~racted free of non-polymeric additives, dried and tested
for oxidation resistance at 90C~ in ~he manner described ln
EXAMPLE 6. On the basis of resn].ts indicated in TABLE VIII,
it is seen that a onsiderable degree of lntrinsic
oxidation resistance has been incorporat2d into poly-
butadiene ~y the use of either MADA or MPDA in ~hls process.
TAB_E VIII
POLYMERS O.R. VALUES AT 90
Polybutadiene control 7.3
Polybutadiene treated with 2.00
parts MADA 6
Polybutadiene treated with 2.00
-~ parts MPDA 58
: EXAMPLE 9
ADDITION OF AMINOMERCAPrANS TO UNSATURATED
HYDROCARSON POLY~CR- I N So~uTloN
. 20 Samples of cis-1.,4-polybutadiene; cis-1,4-poly-
: isoprene; and 15 5-polypentenylene, all of which were free
:: of antioxidants and of free radical inhibitors were
dissolved in benzene and treated with 2.00 parts of an
aminomercaptan in presence of azobis-isobutyro~nitile
(AIBN) catalyst under nitr~gen atomosphere at 70~C. under
~3~ -
~ 3..~7
con~itions indlcated ln Table IX, Polymers were coagulated
lnto isopropyl alcoholg freed of non-polymerlc ma~erials
and tested for oxidatlon res~stance at 90Ca along wlth
control polymers, in the manner described in Example 7
wl~h differen~ amlnomercap~ans identified in Tables I and II~
TABLF, IX
SUBSTRA~E SOLUTION AMINO ~EArT~ON COKDrSl0NS O.R.
MERCAPTAN AIBN TXMEVALUES AT
h~r~ HRSgnoc. HRS
0 ci5-1~4 polybutadienea ~ 9
cls-1,4-polybutadiene MADA 0O40 41 445
cls-lg4-polybu~adlene MPDA 0.20 64 43S
cls-1,4-polybutadieneb IV OD25 64 380 !~
cis-1,4-polybutadlene V 0.~5 64 60
cls-1,4-polybutadiene VI 0.25 64 62
cis-1,4-polybu~adiene VII 0,25 64 62
cis-1,4-polybutadlene x~vf 0.25 64 380
c~s 1~4-polyisopreDe ~ 0~25
cis-1,4-polyisoprene MPDAd 0.25 46 18 : :'
1,5-polypentenylenee --~ 63
1,5 polypentenylenee MPDA 0.40 64 81
a. A 5.00~/O benzene solution of a polymer hav~ng 97%
cis-1j4-structure-
b~ A solu~ion o 100 parts of the same polymer in a
mixture o~ 295 parts he~ane and 585 parts benzene.
.. . . . . .
t~7
c. A 5.00% benzene solution o~ a polymcr having 96~/~
cis-1,4-structure~
d~ Usin~ 4.00 parts of this compoundO
e~ A 5.00% benzene solution of a polymer made by polymeriz-
ing cyclopen~ene with a ~ypical metathesls catalys~O
f. Described in Example 3~
On ~he basis of resul~s indicated in Table IX~ it
. mcy be seen that the intrinsic resistance of the polymeric
slibstrates were considerably enhanced by interaction wi~h an
aminomercaptanO
EXAMPLE 10
INCORPORATION OF MPDA INTO BUTADIENE/
STYRENE COPOLYMER DVRING MILLING AND CURING
A commerclal butadiene/styrene copolymer -
SBR 150~ (containing 23.5% bound styrene), proteeted
with 1.25 parts o~ the non-staining phenolic antioxidant
Wingstay T, (product of the Goodyear Tire and Rubber
Cnmpany) was compounded on a mill with the ingredients
listed in Table X.
TABLE X
INGREDIENTS PARTS BY WEIGHT:
SBR 1502 100
Zlnc ~xide ~5,0
TiO2 30.0
CacO3 24 G ~
Sulfur 2.00
2-Ben~o~hiazolyl,
N-morpholinyl disulflde 1,00
MPDA 2~00
,
Th~ polymer was pressed into an 0.020 i.nch sheet
and cured for 45 minutes at 300F. or to 90 per c~nt of
optimum cure based on Monsanto rheometer dataO A con~rol
polymer, compounded similarly in absence of MPDA was
pressed into a similar sheet which was cured for 30
minutes at 300F. to the same cure level.
A series o one inch strips was cut Erom each
whi~e vulcanizateO Some were ex~racted repeatedly with
80¦20 benzene/ethanol mixture at ambient temperature
over a 2-week period and then ~ried. Times for extracted
strips ~o absorb 1% by wPight o oxygen at 100C. were
compared with times required by non-extracted strips. ~ :
~t may be seen on the basis of data recorded ~.
in TABLE XI that whereas the control SBR vulcanizate
loses most of its resistance to oxidation by extraction
of the antioxidant Wingstay T, that the SBR vulcanizate :.
milled and cured in presence of MPDA retains a very large
percentage of its origioal]y higher resistance to
.
oxidation aEter extraction beca~se of the chemical
incorporation o some of the MPDA into the vulcanizate. ~
TABLE ~I -
0.R VALUES AT 100C; HRS
; VULCANIZATE UNEXTRACTED EXTRACTED
SBR - 1502 Control 95 9 :~
SBR - 1502 compounded with MPDA 250 170
-39-
- '
EXAMPIE 11
Aminomercaptans as conventlonal an~ xldants
for butadiene/styrene copolymer.
A butadlerletstyreDe copolymer was preparecl by
the method used for preparation of SBR-1()06~ Tlhe latex
was shor~stopped at 70% conYersion but was not protected
with commerclal antioxidants. The latex was coagulated
wi~h isopropyl alcohol 9 . extracted ree of non-polymeric
substances with hot ~sopropyl alcohol and vacuum
evaporated. A 3% solution of copolymer in benzene was
preparedc ~Satches of 'chls eement were charged w~th ~.00
levels of dl:Eer~nt amiTIomercaptans . Oxidat~ on resistance
of film~ made rom ~hese cement batches was de~rmlned at
100Co Such values are indicated ln Table XII and compared
- with controls. The structureR of the aminorQercaptans are . .
referred to in Table XII by Rs~man nume~als indentified ln
Tables I or II.
I~ may be seen from Table XII that all of the
aminomercaptans I, IXg~ VII and XIV, when uniormlg
20 distrib~l~ed ln smal:L quantity in SBRa not contalnlng any
. ~ other antioxidant, con~iderably enhance the oxidation
:: reslstance of this polymer in the ~ame manner that the
comEnercial ant~oxidant Wingstay-L does when distrlbuted
in the same manner.
: .:
~40~
'
.
r~7~
TABLE XII
~b~ 0, R ,, VALIIE S AT
None 0 5
415
II 415
VII 450
XIV 181)
loO() par~ of Wingstay-La 300 - 350
a. A hindered phenol-lc antioxidant product of The
Goodyear Tirf~ and ~bber Company.
. Am:1nomercaptans described hereln, some of which
are noYel compoundsg serve as an~iox1dants to sta~ilize
po1ymers against aging when distr1buted thrc)ughout a
polymex by conventional techniques a~ by additi on to a
.~ polymer cement or 1atex" by blendlng Into a solid polymer ~:
on a mill or Banbury, or by mixing wi~h a 1iquid polymer
or solid polymer powder. Sueh am,nomercaptans inc1ude~
- N (4 ani1 Lno phenyl) ~ mercapto-
acetamide,
N-Ç4-ani1ino-pheny1)~ mercap~o-
prop ionamide,
N- ~ , ?' ' dime~hy1-buty1amino)-
phenyl~- ~ -merca~o-propionamide and
N~ mercapto- ~ "~ di~ethyl-~thyl ~ 3
Nl-pheny1~p~phenglene diam~ne
' ' ' ;~'
~ '
- ~ . ~ . . . ~ .. ...
All o~ he compounds except the first are
considered to be new cornpounds. Th~y have antioxidant
propPrties. The last of the compounds has some
antiozonant propextles as well.
~4~- :
.
