CA1084062A

CA1084062A - Sulfur containing bisphenol antioxidants

Info

Publication number: CA1084062A
Application number: CA255,419A
Authority: CA
Inventors: Richard H. Kline
Original assignee: Goodyear Tire and Rubber Co
Current assignee: Goodyear Tire and Rubber Co
Priority date: 1975-07-21
Filing date: 1976-06-22
Publication date: 1980-08-19
Also published as: AU1532176A; IT1062607B; FR2318865B1; MX146113A; DE2629997A1; JPS5213483A; FR2318865A1; BR7604695A; GB1509876A

Abstract

Abstract of the Disclosure Phenolic antioxidants such as bis(3,5-di tert.
butyl-4-hydroxyphenyl) 2,9-dimethyl-4,7-dithiadecanedioate are used to stabilize diene rubbers such as butadiene-styrene copolymers (SBR) and polyolefins such as polypropylene.

Description

; 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 - 1~84~62 phenolic compounds having the following structural formula:

AXAl ;~ wherein A and Al are selected from structures I and II as S follows:

, HO_~ (CH2)x(CH)y(C)zY'COCHCH~ (I) ~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 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.

: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.

:' 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-~-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-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 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 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 .
.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A compound having the following structural formula:

wherein A and A1 are selected from structures I and II
as follows:

(I) (II) and X is wherein Y' is -O- or -NH- and wherein R and R1 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 R8 are selected from 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 -R11- R10-[R12]?2 wherein R9 is an alkylene radical having 2 to 6 carbon atoms, Y is selected from the group consisting of -O-, -S-, 1,4 phenylene and and wherein n1 is 0 or 1, x+y+z is 0 or a whole-number from 2 to 12, R10 is a cycloalkylene radical having from 5 to 12 carbon atoms, R11 and R12 are alkylene radicals 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 which can be substituted or unsubstituted with one or two groups of the structure wherein B conforms to structural formula and wherein R14 is selected from the group consisting of alkyl radicals having 1 to 4 carbon atoms and phenyl and m is 0 or 1 with the proviso that when Y' is -O-, m is 1.

2. A polymer susceptible to oxidative degration having incorporated therein a compound according to Claim 1.

3. The polymer according to Claim 2 wherein A
and A1 have a structure according to structure I.

4. The polymer according to Claim 3 wherein R
and R1 are tert.butyl radicals, R2, R3, R4, R5 and R8 are hydrogen or methyl, R6 is hydrogen, R7 is ethylene, n1 is 0, x is 0 to 3, y is 0 or 1, z is 0 or 1, and x+y+z is 0, 2 or 3.

5. The polymer according to Claim 3 wherein R10 is cyclohexyl, R11 is ethylene and n2 is 0.

6. The polymer according to Claim 2 wherein A
and A1 have a structure according to structure II.

7. The polymer according to Claim 6 wherein R
and R1 are tert.butyl radicals, R5 and R8 are hydrogen or methyl, R6 is hydrogen, R7 and R9 are ethylene and R9 is ethylene or n1 is 0.