Stabilizers and antiozonants for elastomers

Details Stabilizers and antiozonants for elastomers Stabilizers and antiozonants for elastomers

2002-04-15

2004-09-28

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S236000, C524S240000, C524S247000, C524S249000, C524S251000, C524S252000, C524S392000, C524S571000, C524S575500

Reexamination Certificate

active

06797755

ABSTRACT:

The present invention relates to compositions comprising an elastomer susceptible to oxidative, thermal, dynamic, or light- and/or ozone-induced degradation and, as stabilizer, at least one compound of the S-substituted 4-(3-mercapto/sulfinyl-2-hydroxypropylamino)diphenylamine type, and also to the use of the stabilizers to prevent contact discoloration of substrates coming into contact with elastomers, and as antiozonants for elastomers to prevent oxidative, thermal, dynamic, or light- and/or ozone-induced degradation, and also to a process for preventing contact discoloration of substrates coming into contact with elastomers, and to a process for stabilizing elastomers, which comprises incorporating into these, or applying to these, at least one compound of the S-substituted 4-(3-mercapto/sulfinyl-2-hydroxypropylamino)diphenylamine type.
Rubber products (vulcanizates), like all polymers, are susceptible to oxidative, thermal, dynamic or light-induced degradation. A particular factor causing damage to diene rubber vulcanizates is ozone. Ozone attacks the carbon-carbon double bonds, of which many remain in the rubber (vulcanizate), and, via the mechanism known as ozonolysis, causes damage which is apparent as typical surface cracking, and failure of the rubber product. The damage is particularly serious when the rubber product is under dynamic stress.
To prevent ozone damage, antioxidants selected from the class consisting of para-phenylenediamines [see Russel A. Mazzeo et al., “Tire Technology International” 1994, pp. 36-46; or Donald E. Miller et al., Rubber World, 200 (5), 13-23 (1989)] are generally added to vulcanizates. These compounds have very good protective action, especially under dynamic conditions, but develop a strong intrinsic colour (discolouring) and, as a result of high migration rate, these compounds give severe contact discoloration (staining), i.e. the dye transfers to other substrates/products on direct contact. This means that the stabilizers employed in the prior art cannot be used as stabilizers for rubber products which are free from carbon black or are “non-black”, and they are also unsuitable for (black) rubber products which comprise carbon black and are intended for use in direct contact with pale-coloured products.
There continues, therefore, to be a need for colour-stable stabilizers which prevent ozone damage to rubber products, in particular to pale-coloured rubber products. There also continues to be a need for stabilizers which, although they may have an intrinsic colour, are unable, for example as a result of chemical bonding to the rubber chains, to transfer the colour to other products.
The use of compounds of the 1-alkylthio-2-hydroxy-3-aminopropane type as stabilizers for lubricants, hydraulic fluids or metalworking fluids is known from U.S. Pat. No. 4,863,621, for example.
It has now been found that compounds of the S-alkylated 4-(3-mercapto/sulfinyl-2-hydroxypropylamino)diphenylamine type are particularly suitable as stabilizers for elastomers susceptible to oxidative, thermal, dynamic, or light- and/or ozone-induced degradation.
The present invention therefore provides compositions comprising
a) a naturally occurring or synthetic elastomer susceptble to oxidative, thermal, dynamic, light-induced and/or ozone-induced degradation, and
b) as stabilizer, at least one compound of the formula I
[R—S(═O)
m
—CH
2
—CH(OH)—CH
2
]
n
—N(R
1
)
2−n
—R
2
  (I)
 in which
R is C
4
-C
20
alkyl, hydroxyl-substituted C
4
-C
20
alkyl; phenyl, benzyl, &agr;-methylbenzyl, &agr;,&agr;-dimethylbenzyl, cyclohexyl or —(CH
2
)
q
COOR
3
, and, if m is 0, R may additionally be
 and, it n is 1 and R
4
is hydrogen, R may additionally be
R
2
—R
1
N—CH
2
—CH(OH)—CH
2
—S(═O)
m
—(CH
2
)
x
— or
R
2
—R
1
N—CH
2
—CH(OH)—CH
2
—S(═O)
m
—CH
2
—CH
2
—(O—CH
2
—CH
2
)
y
—,
R
1
is hydrogen, cyclohexyl or C
3
-C
12
alkyl,
R
3
is C
1
-C
18
alkyl,
R
4
is hydrogen or —CH
2
—CH(OH)—CH
2
—S(═O)
m
—R,
X is C
1
-C
8
alkyl,
Y is C
1
-C
8
alkyl,
m is 0 or 1,
n is 1 or 2,
q is 1 or 2,
x is from 2 to 6, and
y is 1 or 2.
Alkyl having up to 20 carbon atoms is a branched or unbranched radical, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl or eicosyl. One of the preferred meanings of R is C
4
-C
20
alkyl, in particular C
6
-C
12
alkyl, e.g. C
8
-C
12
alkyl. A particularly preferred meaning of R is tert-nonyl. One of the preferred meanings of R
1
is C
3
-C
12
alkyl, in particular C
3
-C
8
alkyl, e.g. C
3
-C
6
alkyl. A particularly preferred meaning of R
1
is isopropyl or 1,3-dimethylbutyl. A particularly preferred meaning of R
3
is C
1
-C
18
alkyl, in particular C
4
-C
12
alkyl, e.g. C
6
-C
8
alkyl. A preferred meaning of X and Y is C
1
-C
8
alkyl, in particular C
1
-C
4
alkyl, e.g. methyl or tert-butyl.
Hydroxyl-substituted C
4
-C
20
alkyl is a branched or unbranched radical preferably having from 1 to 3, in particular 1 or 2, hydroxyl groups, for example hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl, 2-hydroxybutyl, 5-hydroxypentyl, 4-hydroxypentyl, 3-hydroxypentyl, 2-hydroxypentyl, 6-hydroxyhexyl, 5-hydroxyhexyl, 4-hydroxyhexyl, 3-hydroxyhexyl, 2-hydroxyhexyl, 7-hydroxyheptyl, 6-hydroxyheptyl, 5-hydroxyheptyl, 4-hydroxyheptyl, 3-hydroxyheptyl, 2-hydroxyheptyl, 8-hydroxyoctyl, 7-hydroxyoctyl, 6-hydroxyoctyl, 5-hydroxyoctyl, 4-hydroxyoctyl, 3-hydroxyoctyl, 2-hydroxyoctyl, 9-hydroxynonyl, 10-hydroxydecyl, 11-hydroxyundecyl, 12-hydroxydodecyl, 13-hydroxytridecyl, 14-hydroxytetradecyl, 15-hydroxypentadecyl, 16-hydroxyhexadecyl, 17-hydroxyheptadecyl, 18-hydroxyoctadecyl or 20-hydroxyeicosyl. A preferred meaning of R is hydroxyl-substituted C
4
-C
12
alkyl, in particular hydroxyl-substituted C
5
-C
12
alkyl, e.g. hydroxyl-substituted C
5
-C
11
alkyl.
Interesting compositions comprise, as component b), at least one compound of the formula I in which, if n is 2, R and R
3
have the same meanings.
Preferred compositions comprise, as component b), at least one compound of the formula I in which
R is C
4
-C
12
alkyl, hydroxyl-substituted C
4
-C
12
alkyl; benzyl, &agr;-methylbenzyl, cyclohexyl or —(CH
2
)
q
COOR
3
, and, if m is 0, R may additionally be
 and, if n is 1 and
R
4
is hydrogen, R may additionally be
R
2
—R
1
N—CH
2
—CH(OH)—CH
2
—S(═O)
m
—(CH
2
)
x
— or
R
2
—R
1
N—CH
2
—CH(OH)—CH
2
—S(═O)
m
—CH
2
—CH
2
—(O—CH
2
—CH
2
)
y
—,
R
1
is hydrogen, cyclohexyl or C
3
-C
8
alkyl,
R
3
is C
4
-C
12
alkyl,
X is C
1
-C
4
alkyl,
Y is C
1
-C
4
alkyl,
m is 0 or 1,
q is 1 or 2,
x is from 2 to 4, and
y is 1 or 2.
Preference is also given to compositions comprising, as component b), at least one compound of the formula I in which
R is C
6
-C
12
alkyl, hydroxyl-substituted C
6
-C
12
alkyl; benzyl or —(CH
2
)
q
COOR
3
1
and, if n is 1 and
R
4
is hydrogen, R may additionally be
R
2
—R
1
N—CH
2
—CH(OH)—CH
2
—S(═O)
m
—(CH
2
)
x
— or
R
2
—R
1
N—CH
2
—CH(OH)—CH
2
—S(═O)
m
—CH
2
—CH
2
(OCH
2
—CH
2
)
y
—,
R
1
is cyclohexyl or C
3
-C
8
alkyl,
R
3
is C
6
-C
10
alkyl,
m is 0 or 1,
q is 1 or 2,
x is 2, and
y is 1 or 2.
Particular preference is given to compositions comprising, as component b), at least one compound of the formula I in which
R is C
8
-C
12
alkyl or —(CH
2
)
q
COOR
3
, and, if n is 1 and R
4
is hydrogen, R may additionally be
R
2
—R
1
N—CH
2
—CH(OH)—CH
2
—S(═O)
m
—CH
2
—CH
2
—(O—CH
2
—CH
2
)
y
—,
R
1
is isopropyl or 1,3-dimethylbutyl,
R
3
is C
6
-C
8
alkyl,
R
4
is hydrogen or —CH
2
—CH(OH)—CH
2
—S(═O)
m
—R,
m is 0 or 1,
n is 1 or 2,
q is 1, and
y is 1 or 2.
Compounds of the formula I may, for example, be prepared in a manner similar to tha

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