Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-10-27
2002-04-02
Hoke, Veronica P. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S171000, C564S154000
Reexamination Certificate
active
06365653
ABSTRACT:
The present invention relates to compositions comprising a nonblack elastomer, which is subject to oxidative, thermal, light- or ozone-induced degradation, and as stabiliser at least one thiodipropionic acid bisamide, as well as to the use thereof as colour-stable and non-staining stabilisers and antiozonants for protecting nonblack elastomers against oxidative, thermal, light- or ozone-induced degradation, as well as to a process for stabilising and reducing the discoloration of nonblack elastomers, which comprises incorporating in, or applying to, said elastomers at least one thiodipropionic acid bisamide.
Like all polymers, rubber articles (vulcanisates) are subject to oxidative, thermal or light-induced degradation. A particularly damaging factor for diene rubber vulcanisates is ozone. Ozone attacks the carbon carbon double bonds, many of which are still present in the rubber (vulcanisate) and, via the mechanism known as ozonolysis, results in damages which show as typical surface cracking and as failure of the rubber article. These damages are particularly serious in the case of rubber articles under dynamic stress.
To prevent ozone damages, age protectors from the class of the paraphenylene diamines [see Russel A. Mazzeo et al., Tire technology International 1994, pages 36-46; or Donald E. Miller et al., Rubber World, 200 (5), 13-23 (1989] are usually added to the vulcanisates. These compounds have an excellent protective effect especially under dynamic conditions, but develop strong discoloration and, owing to the high migration rates, exhibit intense contact staining, i.e. the colour transfers to other substrates/articles on direct contact. Therefore, the stabilisers used in the prior art can be used neither for carbon black-free or nonblack rubber articles nor for carbon black-containing (black) rubber articles which are to be used in direct contact with nonblack articles.
There thus continues to be a demand for colour-stable stabilisers protecting nonblack rubber articles against ozone. There is also still a demand for stabilisers which, although they may possess inherent colour, are not able to transfer that colour to other articles owing to, for example, chemical linkage to the rubber chain.
It has now been found that specific thiodipropionic acid bisamides are particularly suitable as stabilisers for nonblack elastomers which are susceptible to oxidative, thermal, light- or ozone-induced degradation.
Accordingly, this invention relates to compositions, which comprise
a) a nonblack elastomer subject to oxidative, thermal, light- or ozone-induced degradation, and
b) at least one compound of formula I
wherein
R
1
is hydrogen, C
1
-C
12
alkyl, cyclohexyl, phenyl or benzyl,
R
2
is hydrogen or C
1
-C
4
alkyl, and
n is the number 0, 1 or 2.
Alkyl containing up to 12 carbon atoms is a branched or unbranched radical, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 1,1-dimethyl-1-propyl, 2-ethyl-butyl, n-pentyl, isopentyl, 2-pentyl, 2-hexyl, 2-heptyl, 2-octyl, n-octyl, nonyl, decyl, undecyl or dodecyl. A preferred meaning of RI is, for example, C
3
-C
12
alkyl, in particular C
3
-C
8
alkyl, e.g. isopropyl. A particularly preferred meaning of R
2
is, for example, methyl and ethyl.
Preferred compositions are those comprising as component (b) at least one compound of formula I, wherein
R
1
is hydrogen or C
3
-C
8
alkyl,
R
2
is hydrogen or methyl, and
n is the number 0 or 1.
Particularly preferred compositions are those comprising as component (b) at least one compound of formula I, wherein
R
1
is hydrogen or C
3
-C
8
alkyl,
R
2
is hydrogen, and
n is the number 0 or 1.
Some of the compounds of formula I are known from the literature and they can be reacted, for example, starting from the known compounds of formula II
with half an equivalent of thio-3,3-bispropionic acid dichloride [preparation see H. Schmid et al., Helvetica Chimica Acta 34, 894-897 (1951)] to the compounds of formula I, wherein n=0. The preparation of the compounds of formula I, wherein n is the number 1 or 2, is carried out, for example, by oxidation of the compounds of formula I, wherein n=0, with an aqueous hydrogen peroxide solution.
Component (b) is suitable for stabilising nonblack elastomers against oxidative, thermal, light- or ozone-induced degradation.
Elastomers are understood as meaning macromolecular materials which, after substantial deformation through minor stress, are capable of rapidly regaining their approximate original shape-at room temperature; see also Hans-Georg Elias, An Introduction to Polymer Science, chapter 12; Elastomers, pages 388-393, 1997, VCH Verlagsgesellschaft mbH, Weinheim, Germany; or Ullmann's Encyclopedia of Industrial Chemistry, Fifth, completely revised Edition, Volume A 23, pages 221-440 (1993).
The compositions of this invention may contain, for example, the following materials as elastomers:
1. Polymers of diolefins, such as polybutadiene or polyisoprene.
2. Copolymers of mono- and diolefins with each other or with other vinyl monomers, such as propylene/isobutylene copolymers, propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethylene/alkylacrylate copolymers, ethylene/alkylmethacrylate copolymers, ethylene/vinyl acetate copolymers, acrylonitrile/butadiene copolymers and terpolymers of ethylene with propylene and a diene, such as hexadiene, dicyclopentadiene or ethylidenenorbornene.
3. Copolymers of styrene or a-methylstyrene with dienes or acryl derivatives, for example styrene/butadiene, styrene/butadiene/alkylacrylate and styrene/butadiene/methacrylate; and also block copolymers of styrene, such as styrene/butadiene/styrene or styrene/isoprene/styrene.
4. Halogen-containing polymers, for example polychloroprene, chlorinated rubber, chlorinated and bromated copolymer of isobutylene/isoprene (halobutyl rubber).
5. Natural rubber.
6. Aqueous emulsions of natural or synthetic rubbers, such as natural rubber latex or latices of carboxylated styrene/butadiene copolymers.
The nonblack elastomer to be protected is preferably a nonblack vulcanised elastomer. Non-black (carbon black-free) polydiene vulcanisates or nonblack halogen-containing polydiene vulcanisates are particularly preferred, in particular nonblack (carbon black-free) styrene/butadiene copolymer vulcanisates.
Component (b) is conveniently added to the elastomer to be stabilised in an amount of 0.2 to 10%, for example of 0.5 to 5%, preferably of 0.8 to 3.0%, based on the weight of the elatstomer to be stabilised.
In addition to components (a) and (b), the novel compositions can also contain further additives, such as the following:
1. Antioxidants
1.1. Alkylated monophenols, for example 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-di-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl4-methylphenol, 2-(&agr;-methylcyclohexyl)-4,6-dimethyl-phenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are linear or branched in the side chains, for example, 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1′-methylundec-1′-yl)phenol, 2,4-dimethyl-6-(1′-methylheptadec-1′-yl)phenol, 2,4-dimethyl-6-(1′-methyltridec-1′-yl)phenol and mixtures thereof.
1.2. Alkylthiomethylphenols, for example 2,4dioctylthiomethyl-6-tert-butylphenol, 2,4-dioctythiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di-dodecylthiomethyl-4-nonylphenol.
1.3. Hydroquinones and alkylated hydroquinones, for example 2,6-di-tert-butyl-4-methoxy-phenol, 2,5-tert-butylhydroquinone, 2,5di-tert-amylhydroquinone, 2,6-diphenyl-4-octade-cyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl4-hydroxyphenyl stearate, bis(3,5-di-tert-butyl-4-hydroxyphenyl) adipate. 1.4. Tocopherols, for example &agr;-tocopherol, &bgr;-tocopherol, &ggr;-tocopherol, &dgr;-tocopherol and mix
Knobloch Gerrit
Meier Hans-Rudolf
Ciba Specialty Chemicals Corporation
Hoke Veronica P.
Mansfield Kevin T.
Stevenson Tyler A.
LandOfFree
Thiodipropionic acid bisamides as stabilizers for nonblack... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thiodipropionic acid bisamides as stabilizers for nonblack..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thiodipropionic acid bisamides as stabilizers for nonblack... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2924517