Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-08-20
1999-03-16
Szekely, Peter A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523351, 524 59, 524 68, 524302, 524303, 524304, 524705, 5253326, 5253335, 525345, C08L 9500, C08L 536, C08C 1926, C08F 3604
Patent
active
058831622
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for the preparation of functionalized elastomer/bitumen compositions with a wide plasticity range. It further relates to the application of the compositions obtained to the production of coatings and in particular of road surfacings, of bituminous mixes or else of watertight facings and it also relates to a mother solution which can be employed for the preparation of the said compositions.
2. Background Art
A description is given, in the citation U.S. Pat. No. 4,011,184, of a process for the preparation of functionalized elastomer/bitumen compositions, one of the methods of preparation of which consists in bringing a bitumen into contact, the operation being carried out at temperatures of between 100.degree. C. and 200.degree. C. and with stirring, with an elastomer, particularly a block copolymer of styrene and of a conjugated diene, in an amount representing 0.1% to 25% and very especially 1% to 5% by weight of the bitumen, and an ethylenically unsaturated carboxylic acid or an anhydride of such an acid, for example maleic anhydride, in a proportion corresponding to 0.5% to 10% of the weight of bitumen and of elastomer, the said contact being maintained for a time sufficient to produce, within the bitumen, a functionalized elastomer carrying carboxylic acid or carboxylic acid anhydride functional groups capable of creating directly, by formation of hydrogen bonds, or by addition of a salifying agent capable of reacting with the carboxyl groups, temperature-reversible bridgings between the macromolecular chains of the elastomer and/or between the said macromolecular chains and the bitumen.
The functionalized elastomer/bitumen compositions obtained as indicated above are less susceptible to gelling phenomena than elastomer/bitumen compositions produced by crosslinking elastomers, such as, in particular, block copolymers of styrene and of a conjugated diene, such as butadiene or isoprene, with sulphur within a bitumen. It is possible, for this reason, to produce functionalized elastomer/bitumen compositions which have a high elastomer content and which can act as concentrates. These compositions are more economical to prepare, to store, and to transport than the corresponding compositions with a lower elastomer content and they can be easily diluted at the time of use, by addition of bitumen, in order to form the elastomer/bitumen binders with a lower elastomer content which are commonly used for the preparation of coatings and in particular of road surfacings.
However, the functionalized elastomer/bitumen compositions prepared by using the abovementioned technique described in the citation U.S. Pat. No. 4,011,184 only have to a limited degree carboxyl functional groups attached to the macromolecular chains of the elastomer associated with the bitumen and capable of inducing crosslinkings or bridgings of the said chains with one another and/or with the bitumen, directly or after addition of the salifying agent. For this reason, the physicomechanical characteristics of such compositions, in particular plasticity range (difference between the ball-and-ring softening temperature and the Fraass brittleness point) and mechanical characteristics at low temperatures of use, are not entirely satisfactory.
SUMMARY OF THE INVENTION
It has now been found that it is possible to obtain, by the abovementioned technique, functionalized elastomer/bitumen compositions exhibiting an expanded plasticity range and improved tensile mechanical characteristics by employing a specific functionalization agent in order to introduce, into the elastomer and optionally into the bitumen, the carboxyl or derived functional groups which induce the crosslinkings.
The subject of the invention is thus a process for the preparation of functionalized elastomer/bitumen compositions with a wide plasticity range, of the type in which a bitumen or mixture of bitumens is brought into contact, the operation being carried out at temperatures of between 100.de
REFERENCES:
patent: 4126482 (1978-11-01), Signouret et al.
patent: 5719216 (1998-02-01), Schermer et al.
patent: 5804619 (1998-09-01), Nicol et al.
Germanaud Laurent
Planche Jean-Pascal
Zins Annie
Elf Exploration Production
Szekely Peter A.
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