Thermotropic copolyester, process for preparing it and use thereof in the preparation of vulcanized rubbers
AssigneeEniricerche S.p.A.
InventorsArnaldo Roggero, Ugo Pedretti, Francesco P. La Mantia, Vincenzo Citta', Alessandro Lezzi
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Abstract
A thermotropic copolyester, which displays a liquid-crystal phase of nematic type, within a desired temperature range, contains units deriving from: (a) a saturated, aliphatic dicarboxy acid; (b) 4,4'-dihydroxy-biphenyl and/or mono- or di-alkyl- or -alkenyl-derivatives thereof; (c) 4-hydroxy-benzoic acid and/or alkyl- or alkenyl-derivatives thereof. Such a copolyester improves the processability of unsaturation-containing elastomers and enhances the mechanical properties of subsequently vulcanized products.
Claims12
A thermotropic copolyester which has a mesophase nematic transition temperature range of from 120.degree. C. to 200.degree. C., consisting essentially of, in its macromolecule, units derived from:
- (a) at least one saturated, aliphatic alpha, omega-dicarboxy acid having the general formula I
- HOOC--(CH.sub.2).sub.N --COOH (I)
- wherein n is 3 to 8;
- (b) at least one 4,4'-dihydroxy-biphenyl having the general formula II ##STR3## (c) at least one 4-hydroxy-benzoic acid having the general formula III ##STR4## wherein R.sub.1, R.sub.2 and R.sub.3 are independently hydrogen, a C.sub.1 -C.sub.6 alkyl, or a C.sub.3 -C.sub.6 -alkenyl, with the proviso that at least one from said three substituents is an alkenyl;
- with the following mutual molar ratios between the units;
- (a)/(b)=1;
- (c)/(a) =1 to 7, with the proviso that, if R.sub.3 is hydrogen, the ratio of (c)/(a) is lower than, or equal to 2.
Dependencies are inferred from the claim text.