Note: Descriptions are shown in the official language in which they were submitted.
2~~~'~~~
-1-
A-17828 +
Stabilizer mixtures for elastomers
The present invention relates to compositions containing an elastomer and a
stabilizer
mixture which consists of a bis-(alkylthiomethyl)-phenol and at least one P-
or
S-containing compound.
Alkylthiomethyl-containing phenols in mixtures with P- and/or S-containing
compounds
are known as stabilizers for elastomers. A 4-component mixture is thus
described, for
example, in EP-A-049,133. It consists of a diphenylamine, a triphenyl
phosphite, a
dialkylthio dipropionate and at least one alkylphenol or bisphenol, for
example
bis-(4-hydroxybenzyl) thioether.
A 3-component mixture for elastomers is known from US-A-3,658,743. It consists
of a
phenol or bisphenol, as mentioned previously in EP-A-049,133, an organic
sulfide or
dialkylthio dialkanoate and an epoxide or phosphite, for example a triphenyl
phosphite.
A 2-component mixture consisting of a phenol and a phosphite is described in
DE-A-2,334,163. The stabilizer mixture contains, for example, 2,6-dialkyl-
substituted
4-(alkyhnercaptomethyl)phenol as the phenolic component and 4-alkyl- or
2,4-dialkyl-substituted triphenyl phosphite.
US-A-3,637,585 furthermore discloses a 2-component mixture which contains an
alkylmercaptomethylphenol in which the alkyl radical carries two
alkoxycarbonyl
substituents, and a dialkylthio alkanoate.
The alkylthiomethyl-containing phenols themselves are likewise known as
stabilizers for
elastomers. Thus, for example, 2,4-bis-(mercaptomethyl)-6-alkylphenols are
described as
particularly active stabilizers in EP-A-0,165,209.
However, there continues to be a need for active stabilizers for elastomers
which are
sensitive towards oxidative degradation.
~~~)~'~~8
-2-
The present invention thus relates to a composition containing an elastomer
and a
stabilizer mixture of
a) a phenol of the formula I
OH
Rt ~ CH2-S-R2
(I>>
R3
CH2-S-R2
and
b) at least one compound of the formulae IIa, IIb and III to VI
C(CH3y3
C9Htg ~ ~ O P
(CHg)gC ~ ~ O P
3 3
(aa) (IIb)
0 0
_ / ~ \ _
R4 P\ /P R4
O O '
(III)
C(CH3 C(CHg)3
(CH3~aC ~ ~ O p ~ ~ ~ ~ p p ~ ~ C(CHg)3 s
~/ 2
(IV)
* Isomer mixture of Nonyl
~~~~'~~8
_3-
CH2CH2-COORS CFi2-OOC-CH2CH2-S-RS
S~ ~ CH2-OOC-CH2CH2-S-RS
nr ~ CH2-OCR-CH2CH2-S-RS
CH2CH2-C;OORg CH2_ppC-CH2CH2-S-RS
cv) cvn
in which Rt is Ct-C4alkyl, the radicals R2 independently of one another are C8-
Cl2alkyl
groups, R3 is hydrogen or methyl, R4 is C18H3~-O- or one of the groups IIIa or
IIIb
C(CHgY3 C(CHgy3
(CH3y3C ~ O CH3 ~ ~ O - , and
C(CH3y3
(IIIa)
(IIIb)
Rg is Ct2-Clsalkyl.
Ct-C4alkyl Rt is, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl,
sec-butyl or
t-butyl. Rt is preferably methyl or t-butyl.
C8-Ct2alkyl RZ is, for example, n-octyl, 2-ethylhexyl, n-decyl, 1,1,3,3-
tetramethylbutyl,
1,1,3,3-tetramethylhexyl, n-undecyl, n-dodecyl or 1,1,3,3,5,5-hexamethylhexyl.
R2 is
preferably n-octyl or n-dodecyl.
Ct2-CtBalkyl RS can be straight-chain or branched and is, for example, n-
dodecyl,
n-tridecyl, n-tetradecyl, 1,1,3,3-teuamethyloctyl, 2-ethylhexyl,
1,1,3,3,5,5-hexamethylhexyl, 1,1,5,5,9,9-hexamethyldecyl, n-hexadecyl or n-
octadecyl. RS
is preferably n-dodecyl, n-tridecyl, n-tetradecyl or n-octadecyl.
Compositions in which Rt is methyl or t-butyl are preferred.
Compositions in which the radicals R2 are n-octyl or n-dodecyl are
particularly preferred.
Compositions in which R4 is ClgHg~-O- are furthermore of interest.
z~J~~~s
-4-
Compositions in which RS is n-dodecyl, n-tridecyl, n-tetradecyl or n-octadecyl
are
likewise of interest.
Compositions which are of particular importance are those in which in
component a) Rl is
methyl, R2 is n-octyl and R3 is hydrogen, and especially in which in component
b) R4 is
C18H37-O- or RS is n-dodecyl or n-tridecyl, or in which a compound of the
formula IIa or
IIb is employed as component b).
Examples of representatives of compounds of the formula I are the substances
listed
below:
2,4-bis(n-oetylthiomethyl)-6-methyl-phenol
2,4-bis(t-octylthiomethyl)-6-methyl-phenol, l
2,4-bis(t-dodecylthiomethyl)-6-methyl-phenol, 2
2,4-bis(n-octyl-thiomethyl)-3,6-dimethyl-phenol,
2,4-bis(2'-ethylhexylthiomethyl)-6-t-butyl-3-methyl-phenol,
2,4-bis(n-octylthiomethyl)-6-t-butyl-phenol,
2,4-bis(n-dodecylthiomethyl)-6-t-butyl-phenol,
2,4-bis(n-octylthiomethyl)-6-t-butyl-3-methyl-phenol,
2,4-bis(n-dodecylthiomethyl)-6-t-butyl-3-methyl-phemol.
Examples of representatives of compounds of the formulae II to VI are the
following
structures:
C(CH3)3
(CH3)3C ~ ~ O P C9H19 ~ ~ O P
3
3
O O
n-C1gH37 '-O- P\ ~P -' O' n-C18H37
O O
1 t-octyl is 1,1,3,3-tetramethylbutyl
2 t-dodecyl is a mixture of 1,1,3,3,5,5-hexamethylhexyl and
1,1,4,6,6-pentamethylhept-(4)-yl
CA 02029708 2002-07-29
29276-177
_S_
C(CHg)3 C (CH3)~
O O
\
(CH3~C ~ ~ O ~ p\ p -.~ O C(CH3)3
O ~_ O
C(CHg)3 C(CH3)3
O O
CH3 ~ ~ O _ p' \p _ O / \ CH3
O
C(CH~y3 C(CH3)~
C(CH3)3 C(CH3)3
(CH3)3C ~ ~ O p ~ ~ ~ ~ - p _ O ~ ~ C(CH3)3
2 2
CH2CH2-COO-n-C12H25 ~ _'H2CH2-COO-n-C13H27
S/ 5
CH2CH2-COO-n-C12H25 \CH2CH2-COO-n-ClgFi27
CH2CH2-COO-Ci4H29 /CH2CH2-COO-C1gH37
S S
CH2CH2-COO-Ci4H29 \CH2CH2-COO-C1gH37
CH2-COO-CH2CH2-S-C12H25 CH2-COO-CH2CH2-S-C18H~7
~CH2-COO-CH2CH2-S-C12H25 ~CH2-COO-CH2CH2-S-Ci8H~7
CH2-COO-CH2CH2-S-C12N25 ~ CH2-COO-CH2CH2-S-CigH37
CH2-COO-CH2CH2-S-C12H25 CH2-C(~-CH2C'.H2-S-CigH37
CA 02029708 2002-07-29
29276-177
-5a-
According to one aspect of t:he present invention,
there is provided a composition containing a.n elastomer and
a stabilizer mixture of a) 2,4-bi.s(ra-octylth.iomethyl)-6-
methylphenol, and b) at least one compound from the group
consisting of tris(,4-nonylphenyl)phosphi.te, tris(2,4-di-
tert-butylphenyl)phosphite, 3,9-bis(~;t~earyloxy)-2,4,8,10-
tetraoxa-3,9-diphosphaspiro[5.5]undecane, tetrakis(3-
dodecylthio-propionyloxymethyl ) methane, bis [(3- (n-
tridecyloxycarbonyl)ethyl]mercaptan, 3,9-bis(2,4-di-tert-
butylphenoxy)-2,4,8,10-tetraoxa-3,9-
diphosphaspiro[5.5]undecane, and 3,9-bis(2,4-di-tert-butyl-
6-phenylphenoxy)-2,4,8,10-tet.raoxa-~,9-diphosphaspiro[5.5]-
undecane.
The compositions according to the invention can,
for example, contain the following mat:ezials as elastomers:
1. Polydienes, for exam~>le polybutadiene, polyisoprene or
polychloroprene; and block polymers, f:or example
styrene/butadiene/styrene, styrene/isoprene/styrene and
acrylonitrile/butadiene copolymers or styrene/butadiene
copolymers.
2~fl?~'~~)~
-6-
2. Copolymers of mono- and diolefins with one another or with other vinyl
monomers, for
example etlhylene-alkyl acrylate copolymers, ethylene-alkyl methacrylate
copolymers,
ethylene-vinyl acetate copolymers and terpolymers of ethylene with propylene
and a
diene, such as hexadiene, dicyclopentadiene or ethylidenenorbornene.
3. Halogen-containing polymers, for example polychloroprene, chlorinated
rubber,
chlorinated or chlorosulfonated polyethylene, epichlorohydrin homo- and
copolymers,
chlorotrifluoroethylene copolymers and polymers of halogen-containing vinyl
compounds,
for example polyvinylidene chloride and polyvinylidene fluoride; and
copolymers thereof,
such as vinyl chloride-vinylidene chloride, vinyl chloride-vinyl acetate or
vinylidene
chloride-vinyl acetate.
4. Polyurethanes which are derived on the one hand from polyethers, polyesters
and
polybutadiene having terminal hydroxyl groups and on the other hand from
aliphatic or
aromatic polyisocyanates, and intermediates thereof.
5. Natural rubber.
6. Mixtures (polyblends) of the abovementioned polymers.
7. Aqueous emulsions of natural or synthetic rubbers, for example natural
rubber latex or
latices of carboxylated styrene/butadiene copolymers.
If appropriate, these elastomers are in the form of latices and can be
stabilized as such.
Compositions which contain a polydiene, such as polybutadiene rubber, a
halogenated
polymer, such as polyvinylidene fluoride, or a polyurethane as the elastorner
are preferred.
Compositions which contain polybutadiene rubber as the elastomer are
particularly
preferred.
The compositions according to the invention advantageously contain 0.01-10 %
by weight
of the stabilizer mixture of a) and b), based on the elastomer, in particular
O.OS-5.0, for
example 0.05-3 and especially 0.1-2 % by weight: Mixtures of stabilizers of
the formula I
and/or of the formulae II to VI can likewise be employed. The ratio of the two
components
a) and b) to one another can vary within wide limits. The weight ratio a):b)
is
2~?~'~~8
_7_
advantageously 9:1 to 1:9, for example 2:8 to 8:2 or 3:7 to 7:3. Preferred
ratios are in the
range from 2:1 to 1:2, in particular about 1:1 to 1:2.
The incorporation into the elastomers can be carried out, for example, by
mixing in of the
substances of the formulae I-VI and if appropriate further additives, for
example
vulcanization accelerators, fillers, plasticizers or pigments, by the methods
customary in
the art, before or during shaping, or by application of the dissolved or
dispersed
compounds to the polymer, if appropriate with subsequent evaporation of the
solvent. The
compounds of the formulae I-VI can also be added to the plastics to be
stabilized in the
form of a masterbatch which contains these compounds, for example, in a
concentration of
2.S to 25 % by weight.
The compounds of the formulae I-VI are prepared by methods which are known per
se,
such as are described, for example, in EP-A-0,165,209 and in US-A-3,227,677 in
respect
of the formula I. However, they can also be obtained by reaction of a phenol
of the
formula Ia
OH
(Ia)
R3
in which Rt and R3 have the abovementioned meaning, with formaldehyde or a
compound
which liberates formaldehyde under the reaction conditions and with at least
one
mercaptan Rz-SH in the presence of a base, the base being mono-, di- or
trimethylamine or
mono- or diethylamine.
All the starting substances are known compounds and can be prepared by known
processes. Some of them are also commercially available.
The following examples illustrate the invention in more detail. Percentages
and parts in
the examples are percentages by weight and parts by weight.
2~~~'~4~8
-8-
PREPARA'I°ION EXAMPLES
Example 1: Preparation of 2,4-bis(n-octylthiomethyl)-6-methylphenol
OH
CHg ~ CH2-S-n-CgHl7
CH2-S-n-C8H 17
160.74 g (0.72 mol) of 2,4-bis(dimethylaminomethyl)-6-methylphenol and 210.65
g (1.44
mol) of n-octanethioi are heated at 150°C in an apparatus having a
stirrer and intensive
cooler for 36 hours, dimethylamine being stripped off continuously under 53.2
bar.
291.6 g (95 %) of a yellow oil are obtained. Pure 2,4-bis(n-octylthiomethyl)-6-
methylphenol is obtained as a colourless oil by column chromatography of the
crude
product on silica gel.
Analysis values:
Calculated 70.69 % C Found 70.85 % C
10.44%H 10.42%H
15.09%S 15.11%S
Example 2: Preparation of 2,4-bis(n-octylthiomethyl)-6-t-butylphenol
OH
(CHgy3C / CH2-S-n-C8H17
CHZ-S-n-C8H17
A mixture of 22.5 g of 6-t-butylphenol, 18.0 g of parafozmaldehyde , 43.9 g of
n-octanethiol, 4.0 g of 33 % ethanolic dimethylamine and 23 ml of
N,N-dimethylformamide is refluxed under nitrogen in a sulfonating flask having
a reflux
condenser and mechanical stirrer for 3 hours. The internal temperature is
110°C. The
2~9~~'~~8
-9-
crude product is taken up in 150 ml of ethyl acetate and the mixture is washed
with 100 ml
of water. After evaporation of the organic phase to dryness, 51 g (97 % of
theory) of
2,4-bis-(n-actylthiomethyl)-6-t-butyl-phenol are obtained as a colourless oil.
Analysis values:
Calculated: 13.74 % S
Found: 13.44 % S.
USE EXAMPLES
Example 3: Stabilization of polybutadiene rubber (silicone oil ageing)
100 g of polybutadiene which is prestabilized with 0.4 % of 2,6-di-t-butyl-p-
cresol are
mixed homogeneously with 0.15 % of stabilizer component a) and 0.3 % of
stabilizer
component b) on a mixing mill at 50°C for 6 minutes. Sheets 2 mm thick
are pressed from
the rolled hide at 80°C. Anather sheet without stabilizer is produced
in the same manner.
The test specimens are aged by immersion in silicone oil at 160°C for
30 minutes. The
criterion is the gel content at the end of ageing. The gel content is
determined as follows:
After ageing, the sample is dissolved in 100 ml of toluene at room
temperature. After 24
hours, the solution is filtered through a wire sieve (in accordance with ASTM
E 11 No.
400) and the residue is carefully washed and dried. The gel content is
obtained from
Fg - Fo
Gel = x 100 (%)
E
Fg = weight of the filter with the gel
Fo = weight of the empty filter
E = weight of the sample
The results are summarized in the following Table 1.
~~,'~~'~~)8
- lo-
Table 1
StabilizerStructure Gel content
(%)
None - 10.2
A 2,4-Bis(n-octylthiomethyl)-6-methylphenol2.4
B A + Tris(4-nonylphenyl) phosphite1.0
A + Tris(2,4-di-t-butylphenyl)p,g
phosphite
D A + 3,9-Bis(stearyloxy)-2,4,8,10-tetraoxa-1.1
3,9-diphosphaspiro[5,5]undecane
E A + Tetrakis(3-dodecylthio-propionyl-0.4
oxymethyl)-methane
F A + Bis[ (3 -(n-tridecyloxycarbonyl)ethyl]-1.2
mercaptan
If stabilizer A in the above preparation example is replaced by
2,4-bis(n-octylthiomethyl)-6-t-butylphenol from Example 2, similarly good
stabilization
values are obtained with the analogous stabilizer combinations.
Example 4: Stabilization of polybutadiene rubber (silicone oil ageing)
The experiment is carried out in a manner analogous to that described in
Example 3, but
the ageing takes place in silicone oil at 160°C for 45 minutes. The
results are listed in the
following Table 2.
2~~~'~~8
Table 2
StabilizerStructure Gel
conten
None 22.05
A 2,4-Bis(n-octylthiomethyl)-6-methylphenol3.75
C A + Tris(2,4-di-t-butylphenyl)2.30
phosphite
G A + 3,9-Bis(2,4-di-t-butylphenoxy)-2.55
2,4,8,10-tetraoxa-3,9-diphosphaspiro-
[5,5]undecane
H A + 3,9-Bis(2,4-di-t-butyl-6-methylphenoxy-1.98
2,4,8,10-tetraoxa-3,9-diphosphaspiro-
[5,5]undecane
