Covulcanizable anti-aging agents

Details Covulcanizable anti-aging agents Covulcanizable anti-aging agents

2001-05-07

2003-10-07

Harlan, Robert D. (Department: 1713)

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

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C564S430000, C564S434000

Reexamination Certificate

active

06630540

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to covulcanizable anti-aging agents, which are capable of imparting long-lasting protection from thermal aging and fatigue, and from aging due to the effects of oxygen, to vulcanized rubber products. The anti-aging agents according to the present invention are also distinguished by the fact that they are practically hardly extracted from the vulcanized products by water, by oil and/or petrol, or by hydraulic fluids.
BACKGROUND OF THE INVENTION
It is known that vulcanized rubber products can be protected by anti-aging agents from environmental effects, which destroy these vulcanized products. Thus, for example, known phenolic, aminic, sulfur-containing or phosphorus-containing anti-aging agents are added in order to improve the thermal stability and shelf life of vulcanized rubber products. These are described in greater detail in Ullmann's Enzyklopädie der technischen Chemie, Volume 8, page 19 et seq., for example.
Moreover, it is known that the volatility of anti-aging agents can be reduced by depositing them on support materials and/or by providing them with reactive groups so that they are copolymerized during the production of the rubber, or by depositing them by grafting on the rubber to be protected before vulcanization. Anti-aging agents which are modified in this manner are described, for example, in JP 61 111 343, by W. Schunk, Gummi, Fasern, Kunstst. 43 (3), (1990), 138-144, by R. H. Kline and J. P. Miller, Rubber Chem. Technol. 46 (1), (1973), 96-105, in EP 466 263, DE 19 718 288 and EP 120 801, by H. Fries, Gummi, Asbest, Kunstst. 40. (1987), 238-258, by D. Braun, R. Rettig, W. Rogler, Angew. Makromol. Chem. 211, (1993), 165-194, in DE-A 3 430 510, by G. Scott and S. M. Tavakoli, Polym. Degrad. Stab. 4 (4), (1982), 279-285, and by A. H. Weinstein, Rubber Chem. Technol. 50 (4), (1977), 650-659.
The disadvantages of the anti-aging agents for vulcanized rubber products which have been known hitherto is first, their volatility or ease of extraction, and second, particularly for modified anti-aging agents, is that they are added during the polymerization of the monomers for the production of the rubber are and, therefore, have an adverse effect on the polymerization reaction (e.g. they reduce the rate of reaction).
SUMMARY OF THE INVENTION
The object of the present invention, is thus to provide an anti-aging agent which first does not have an adverse effect on the polymerization of monomers and which second, does not exhibit the volatility and ease of extraction of known anti-aging agents, without the efficacy of the anti-aging agents according to the present invention being reduced compared with that of anti-aging agents which were known hitherto.
The present invention relates to covulcanizable anti-aging agents, which can be produced by the reaction of p-phenylenediamines, which are optionally substituted, and/or of sterically hindered phenols, with bifunctional alkyl, aryl and/or aralkyl compounds and subsequent reaction of the products thus obtained with sulfur and/or with sulfur donor compounds.
DETAILED DESCRIPTION OF THE INVENTION
Suitable p-phenylenediamines, which are optionally substituted, are those of formula (I):
where
R
1
to R
4
are identical or different and represent hydrogen, a straight chain or branched C
1
-C
12
-alkyl, a C
1
-C
12
-alkoxy, a C
1
-C
12
-alkyl-thio, a C
1
-C
12
-alkyl-amino, a di-(C
1
-C
12
-alkyl)-amino, benzyl, 1,1-di-methylbenzyl or phenyl,
and
R
5
represents hydrogen, phenyl, a C
6
-C
12
-aryl, a C
1
-C
12
-heteroaryl or a C
1
-C
12
-alkyl.
C
1
-C
12
-alkyl radicals are to be understood to mean all linear, cyclic or branched alkyl radicals containing 1 to 12 C atoms which are known to one skilled in the art, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, n-pentyl, i-pentyl, neo-pentyl, n-hexyl, cyclohexyl, i-hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl radicals, which may in themselves be substituted.
Suitable substituents include halogen, nitro and hydroxyl groups, and also include C
1
-C
12
-alkyl, C
1
-C
12
-alkoxy, C
5
-C
12
cycloalkyles C
6
-C
12
-aryl and C
1
-C
12
-heteroaryl radicals, such as benzyl, trimethylphenyl, ethylphenyl, chloromethyl, chloroethyl or nitromethyl radicals.
C
1
-C
12
-alkoxy radicals are to be understood to mean all linear, cyclic or branched alkoxy radicals containing 1 to 12 C atoms which are known to one skilled in the art, such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, t-butoxy, n-pentoxy, i-pentoxy, neopentoxy and hexoxy radicals, which may themselves be substituted by the aforementioned substituents.
C
5
-C
12
-cycloalkyl radicals are to be understood to mean all mono- or polynuclear cycloalkyl radicals containing 5 to 12 C atoms which are known to one skilled in the art, such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and cyclononyl radicals, which may themselves be substituted by the aforementioned substituents.
C
6
-C
12
-aryl radicals are to be understood to mean all mono- or polynuclear cycloalkyl radicals containing 6 to 12 C atoms which are known to one skilled in the art, such as phenyl or naphthyl radicals, which may themselves be substituted by the aforementioned substituents.
C
1
-C
12
-heteroaryl radicals are to be understood to mean all mono- or polynuclear heteroalkyl radicals which are known to one skilled in the art, and which in addition to 1 to 12 C atoms also contain heteroatoms such as N, S, O and/or P in their aromatic ring system, e.g. pyridinyl, triazinyl, furyl, thienyl, thiazolyl, thiazinyl, pyrrolyl and quinolinyl, which themselves may be substituted by the aforementioned substituents.
A preferred embodiment of p-phenylenediamines of formula (I) are those in which
R
1
to R
4
represent hydrogen, methyl, ethyl, propyl, t-butyl, 2-propyl, 2-butyl, methoxy, ethoxy, cyclohexyl, benzoyl, phenyl, naphthyl, chlorophenyl or toluyl,
and
R
5
represents hydrogen, 2-propyl, 1,3-dimethylbutyl or cyclohexyl.
A preferred embodiment of sterically hindered phenols are those of general formula (II):
in which
R
6
and R
7
are identical or different and represent hydrogen, a straight chain or branched C
1
-C
12
-alkyl, a bridging C
1
-C
12
-alkenyl, or di(cyclopentadiene)diyl,
and
R
8
has the meaning of R
6
or R
7
, or represents a C
6
-C
12
-arylthio, a branched or straight chain C
1
-C
12
-alkylthio, or a grouping of formula:
with the aforementioned meaning of R
6
or R
7
.
The sterically hindered phenols which are preferably used are those in which
R
6
and R
7
represent hydrogen, methyl, ethyl, 2-propyl, tert.-butyl, 1,1-dimethylpropyl, cyclohexyl, cyclopentyl, methylene, ethylene, butylene or iso-butylene,
and
R
8
denotes hydrogen, methyl, tert.-butyl, 2-propyl, 2-butyl, cyclohexyl, cyclopentyl, nonylthio, dodecylthio or cyclohexylthio.
The p-phenylenediamines and sterically hindered phenols which are used for the production of the anti-aging agents according to the present invention are known to one skilled in the art and are described, for example, by J. G. Gillick, Elastomerics, 120 (8), (1988), 17-19, by K. B. Chakraborty, G. Scott and J. Rekers, Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 26 (2), (1985), 31, by J. A. Kuczkowski and J. G. Gillick, Rubber Chem. Technol. 57 (3), (1984), 621-651, by G. Scott, Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.), 25 (1), (1984), 62-63 and by G. Scott, Gummi, Asbest, Kunstst. 31 (12), (1978), 934-938, 940, 966.
Compounds of formulae (III), (IV) and (V) can be used as bifunctional alkyl, aryl and/or aralkyl compounds:
(F
1
)
n
-alkanediyl-(F
2
)
m
  (III)
(F
1
)
n
-aralkanediyl-(F
2
)
m
  (IV)
(F
1
)
n
-arenediyl-(F
2
)
m
  (V)
in which
F
1
represents chlorine, bromine, iodine, a hydroxyl, a carbonyl, a carboxyl, an olefin, an alkyne, a sulfate, a sulfonate, a phosphate, a carbonate, an isocyanate or an isothiocyanate,
and
F
2
represents a halogen, an olefin, an alkyne, a phosphate or a thiophosphate, hydrogen sulfide, a di- or trisulfane, or a sulfite or thiosulfate,
wherei

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