Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-10-16
2003-07-22
Egwim, Kelechi (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S330000, C524S331000
Reexamination Certificate
active
06596796
ABSTRACT:
The present invention relates to compositions comprising an emulsion crude rubber, synthetic latex or natural rubber latex subject to oxidative, thermal, dynamic and/or light-induced degradation and, as stabiliser, at least one compound of the &bgr;-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid ester type, and also to the use thereof as colour-stable and non-discolouring stabilisers for stabilising emulsion crude rubbers, synthetic latices or natural rubber latices against oxidative, thermal, dynamic and/or light-induced degradation, and to a method of stabilising emulsion crude rubbers, synthetic latices or natural rubber latices, in which method at least one compound of the &bgr;-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid ester type is incorporated therein or applied thereto.
The present invention relates also to compositions comprising, in addition to at least one stabiliser of the &bgr;-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid ester type, also at least one stabiliser of the alkylthiomethylphenol type, and to the use of such stabiliser combinations and also to a method of stabilising emulsion crude rubber, synthetic latex or natural rubber latex therewith, especially carboxylated latex.
Those stabiliser combinations consisting of &bgr;-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid esters and alkylthiomethylphenols exhibit a synergistic effect.
The stabilisers used in the composition according to the invention are all generally in liquid form and yield stable emulsions that have not been obtainable hitherto using solid stabilisers.
Emulsion rubbers are manufactured by emulsion polymerisation. Emulsion polymerisation in water, which is initiated with redox initiators at low temperatures (cold rubber) or at relatively high temperatures (hot rubber) with organic peroxides or persulfates, as the case may be, yields latices that are used as such or are processed to yield solid rubber. The molar weights of emulsion SBR are in the range of about from 250 000 to 800 000 g/mol; cold and hot rubbers differ in the degree of branching. The rubbers are sold as such or blended with oil or loaded with carbon blacks and constitute the most important synthetic rubbers.
Natural rubber latex and a wide variety of types of synthetic latices are available commercially. Polymer latices are colloidal dispersions of rubber or of a plastic material in an aqueous medium. The polymeric material may be a polymer of small ethylenic (olefinic) monomers or diene monomers or alternatively a copolymer of two or more such monomers. The mechanical stability of such latices depends principally upon the presence of surface-active substances at the interface between polymer particle and aqueous phase.
Most synthetic latices consist of styrene-butadiene, styrene-acrylic acid, acrylic acid esters, vinyl acetate-acrylate or butadiene-acrylonitrile. Carboxylated latices, such as carboxylated SBRs, additionally comprise, for example, up to 5% of the monomer unit containing the carboxyl group or corresponding carboxylic acid esters. Advantageously there are used as organic acid unsaturated mono- and di-carboxylic acids, such as acrylic acid, methacrylic acid and, for example, methylenesuccinic acid (itaconic acid). As carboxylic acid esters, which are used, for example, as comonomers for vinyl acetate, there is principally used fumaric acid diethyl ester, maleic acid diethyl ester, methyl acrylate, n-butyl acrylate or 2-ethylhexyl acrylate.
The organic acid used determines, to a considerable degree, the properties of the carboxylated SBRs obtained at reaction temperatures of from about 60 to about 100° C. There may be mentioned by way of example the water solubility or the final working properties, which are substantially influenced by the number of carboxyl groups on the surface of the latex. A typical mixture of components and the properties thereof are described in Polymer Latices and their Application (Applied Science Publishers Ltd., London 1982; Editor K. O. Calvert), pages 29 to 31. The main use of such X-SBRs is in the paper industry, the adhesives industry and also in the textile industry and, in the latter case, specifically in the field of carpeting. In the paper industry, carboxylated latices are used, for example, for surface-coatings for paper; in the adhesives industry they are used, for example, for dispersion adhesives and in the dyestuffs industry they are used, for example, for disperse dyes.
The articles produced from the latex have to be stabilised against the action of heat and oxygen by means of anti-oxidants.
The use of emulsions consisting, for example, of compounds of the &bgr;-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid ester type as stabilisers for organic polymers is known, for example, from U.S. Pat. No. 3,962,123. U.S. Pat. No. 5,658,866 describes specific stabilisers of the &bgr;-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid ester type in lubricating oil compositions.
The use of compounds of the 2-methyl-4,6-bis(alkylthiomethyl)phenol type is described in U.S. Pat. No. 4,857,572.
It has now been found that certain compounds of the &bgr;-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid ester type are especially suitable as stabilisers for emulsion crude rubbers, synthetic latices or natural rubber latices that are sensitive to oxidative, thermal, dynamic and/or light-induced degradation.
The present invention accordingly relates to compositions comprising
a) an emulsion crude rubber, synthetic latex or natural rubber latex subject to oxidative, thermal, dynamic and/or light-induced degradation, and
b) as stabiliser at least one compound of formula I
wherein R
1
is C
8
-C
20
alkyl.
Of interest are compositions wherein R
1
is C
8
-C
13
alkyl, especially branched C
8
-C
13
alkyl.
Of special interest are compositions wherein R
1
is isooctyl and/or isotridecyl.
Of very special interest are compositions wherein R
1
is isooctyl or isotridecyl.
The compositions according to the invention advantageously comprise c) as further stabiliser at least one compound of formula II
wherein
R
2
is C
8
-Cl
2
alkyl,
R
3
is hydrogen, C
1
-C
12
alkyl, cyclohexyl, 1-methylcyclohexyl, benzyl, &agr;-methylbenzyl, &agr;,&agr;-dimethylbenzyl or —CH
2
—S—R
2
,
R
4
is C
1
-C
12
alkyl, benzyl, &agr;-methylbenzyl, &agr;,&agr;-dimethylbenzyl or —CH
2
—S—R
2
, and
R
5
is hydrogen or methyl.
Of interest are compositions wherein R
2
is C
8
alkyl or C
12
alkyl.
Of special interest are compositions wherein
R
3
is C
1
-C
8
alkyl, benzyl or &agr;-methylbenzyl,
R
4
is C
1
-C
9
alkyl or —CH
2
—S—R
2
, and
R
5
is hydrogen or methyl.
Of particular interest are compositions wherein
R
3
is C
1
-C
4
alkyl or benzyl,
R
4
is C
1
-C
4
alkyl or —CH
2
—S—R
2
, and
R
5
is hydrogen or methyl.
Preference is given to compositions wherein
R
2
is C
8
alkyl or C
12
alkyl,
R
3
is methyl,
R
4
is —CH
2
—S—R
2
, and R
2
is C
8
alkyl or C
12
alkyl, and
R
5
is hydrogen.
The combinations of components (b) and (c) of formulae I and 11 exhibit a synergistic action upon the substrate to be stabilised, that is to say upon the emulsion rubber, the synthetic latex or the natural rubber latex and articles manufactured therefrom.
Alkyl having up to 20 carbon atoms denotes a branched or unbranched radical, for example 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
1
is branched C
8
-C
13
alkyl, especially isooctyl and/or isotridecyl, more especially isooctyl or isotridecyl. One of the preferred meanings of R
2
is C
8
-C
12
alkyl, especially C
8
alkyl or C
12
alkyl.
The compounds of the &bgr;-(5-tert-butyl-4-hydroxy-3-
Dubs Paul
Evans Samuel
Knobloch Gerrit
Meier Hans-Rudolf
Ciba Specialty Chemicals Corporation
Egwim Kelechi
Mansfield Kevin T.
LandOfFree
Stabilizers for emulsion crude rubbers, synthetic latex and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stabilizers for emulsion crude rubbers, synthetic latex and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stabilizers for emulsion crude rubbers, synthetic latex and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3099106