Compositions – Preservative agents – Anti-oxidants or chemical change inhibitants
Reexamination Certificate
2001-10-22
2004-03-16
Anthony, Joseph D. (Department: 1714)
Compositions
Preservative agents
Anti-oxidants or chemical change inhibitants
C252S401000, C564S305000, C564S402000, C564S415000, C564S434000, C524S254000, C524S255000, C524S541000
Reexamination Certificate
active
06706217
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a liquid antiozonant made up of a reaction product of unsubstituted and/or substituted paraphenylenediamine compounds and a carbonyl compound mixture formed from acetone and at least one other carbonyl compound and to rubber compositions containing same.
It is well known that ozone causes surface cracking of conventional highly unsaturated rubber vulcanizates when the rubber is placed under strain in an ozone environment. The function of ozone is purely a surface phenomenon. The most severe deterioration occurs when a small number of cracks are formed which grow rapidly into deep, disruptive fissures. The function of an antiozonant depends on its migration to the surface of the rubber article where protection against the ozone attack is needed.
Chemical antiozonants have therefore been developed to retard the formation of ozone cracks occurring under static and dynamic conditions. Widely used antiozonants in protecting vulcanized rubber from ozone attack are N,N′-disubstituted paraphenyldiamines. Examples of these antiozonants in common use include N-phenyl-N′-(1,3-dimethylbutyl)-p-phenylenediamine; N-phenyl-N′-isopropyl-p-phenylenediamine; N-phenyl-N′-(1,4-dimethylpentyl)-p-phenylenediamine; N-phenyl-N′-(1-methylheptyl)-p-phenylenediamine; N-phenyl-N′-cyclohexyl-p-phenylenediamine; mixed diaryl-p-phenylenediamines; N,N′-diphenyl-p-phenylenediamine; N,N′-di-beta-naphthyl-p-phenylenediamine; N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine; N,N′-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine; N,N′-bis(1-methylheptyl)-p-phenylenediamine; and N-phenyl-N′-p-toluenesulfonyl-p-phenylenediamine.
Blends of two or more paraphenylenediamine materials have been used in rubber and provide certain advantages over individual paraphenylene materials. For example, it has been found advantageous to blend two or more paraphenylenediamines for the purpose of obtaining a product which can be handled as a liquid under normal temperatures. Blends are also used where the particular properties of two or more paraphenylenediamines are desired in a single product.
In general, blends have typically been produced by physically mixing two or more separately prepared paraphenylenediamine materials but this process requires additional storage and mixing equipment. Another process includes, for example, U.S. Pat. No. 3,542,691 which discloses a one-step process for preparing a liquid N-alkyl-N′-phenyl-paraphenylenediamine system by reductively alkylating at least one nitrogen-containing compound selected form the group consisting of p-nitrodiphenylamine, p-aminodiphenylamine and p-nitrosodiphenylamine by reacting the nitrogen containing compound with a mixture of 4-methyl-2-peritanone and 5-methyl-2-hexanone in the presence of hydrogen and a reductive alkylation catalyst.
Yet another example is European Patent Application No. 084,527 which discloses a process for preparing a mixture of two or more different N,N′-disubstituted paraphenylenediamines by the reductive alkylation of a nitrogen-containing compound selected from 4-nitrodiphenylamine, 4-aminodiphenylarnine, paranitroaniline and phenylenediamine with two or more ketones wherein the ketones are charged sequentially and each ketone is reacted essentially to completion before charging the next.
SUMMARY OF THE INVENTION
In accordance with the present invention, a liquid antiozonant mixture is provided which is obtained from the process comprising simultaneously reacting at least one unsubstituted and/or substituted paraphenylenediamine compound of the general formula
wherein R
1
and R
2
are the same or different and are hydrogen, a branched or straight chain alkyl, alkenyl, alkoxyl, aralkyl, alkaryl, hydroxyalkyl or heterocyclic; with a carbonyl compound mixture comprising acetone and at least one other carbonyl compound selected from the group consisting of ketones containing from 4 to about 12 carbon atoms, aldehydes containing from 1 to about 12 carbon atoms and mixtures thereof in the presence of a reductive alkylation catalyst.
Additionally, rubber compositions containing the foregoing liquid antiozonant mixtures are also provided herein. The rubber compositions can be, for example, tires, motor mounts, rubber brushings, windshield wiper blades, etc.
The liquid antioxonant mixtures obtained from the process described herein advantageously provides unsubstituted and/or substituted paraphenylenediamines, which have been reductively alkylated with a arbonyl compound mixture formed from acetone and at least one other carbonyl compound, e.g., ketones and/or aldehydes, possessing different migratory rates for use in rubber compositions, e.g., tire compositions, thereby providing greater protection against ozone attack and, therefore, extending the life expectancy of the rubber composition. Additionally, by employing acetone with at least one other carbonyl compound in the process described herein, the antiozonant mixture possesses greater reduced temperature stability in maintaining its liquid state.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The liquid antiozonant mixtures of this invention are obtained by simultaneously reacting at least one unsubstituted and/or substituted paraphenylenediamine compound of the general formula
wherein R
1
and R
2
are the same or different and are hydrogen, a branched or straight chain alkyl from 1 to about 24 carbon atoms; alkenyl; alkoxyl; aralkyl; alkaryl; hydroxyalkyl or heterocyclic, e.g., pyrrolidine, piperidine, piperazine, morpholine, 2-(2-aminoethyl)-1-methylpyrrolidine, 4-(2-aminoethyl)morpholine, 1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, 1-(2-aminoethyl)piperazine, etc.; with a carbonyl compound mixture formed from acetone and at least one other carbonyl compound selected from the group consisting of ketones containing from 4 to about 12 carbon atoms, aldehydes containing from 1 to about 12 carbon atoms and mixtures thereof in the presence of a reductive alkylation catalyst.
Many of the starting unsubstituted and/or substituted paraphenylene-diamines and their preparation are well known. See, e.g., U.S. Pat. Nos. 5,420,354; 5,574,187 and 5,840,982, the contents of which are incorporated by reference herein. Examples of suitable unsubstituted and substituted paraphenylenediamines for use herein include paraphenylenediamine, paraaminodiphenylamine, N,N′-bis(1-methylheptyl)-p-phenylenediamine; N,N′-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine, N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,N-di-beta-naphthyl-p-phenylenediamine, N-o-tolyl-N′phenyl-p-phenylenediamine, N,N-di-p-tolyl-p-phenylenediamine, N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine, N-1,4-dimethylpentyl-N′-phenyl-p-phenylenediamine, N-isopropyl-N′-phenyl-p-phenylenediamine, N-1-methylpropyl-N′-phenyl-p-phenylenediamine, N-cyclohexyl-N′phenyl-p-phenylenediamine, N,N′-bis-(1-ethyl-3-methylpentyl)-p-phenylenediamine, N,N′-bis-(1,4-dimethylpentyl)-p-phenylenediamine, N,N′-bis-(1-methylpropyl)-p-phenylenediamine, N-phenyl-N′-(1,3-dimethylbutyl)-p-phenylenediamine; N-phenyl-N′-isopropyl-p-phenylenediamine; N-phenyl-N′-(1-methylheptyl)-p-phenylenediamine; N-phenyl-N′-cyclohexyl-p-phenylenediamine; mixed diaryl-p-phenylenediamines; N,N′-bis(1-methylheptyl)-p-phenylenediamine; N-phenyl-N′-p-toluenesulfonyl-p-phenylenediamine; N-phenyl-N′-alkyl-p-phenylenediamine; and the like and combinations thereof. Preferred starting paraphenylenediamine compounds for use herein are paraphenylenediamine and paraaminodiphenylamine.
Suitable ketones containing from 4 to about 12 carbon atoms to include with acetone in forming the carbonyl compound mixture thereof to react with the foregoing paraphenylenediamine compounds include methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone, ethyl propyl ketone, ethyl isopropyl ketone, dipropyl ketone, diisopropyl ketone, methyl b
Gencarelli Richard A.
Malz, Jr. Russell E.
Reynolds Michael P.
Anthony Joseph D.
Reitenbach Daniel
Uniroyal Chemical Company, Inc.
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