Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1995-11-13
1998-05-26
Szekely, Peter A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524 59, 524 69, 524 70, 524 71, C08L 9500
Patent
active
057565651
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to non-gellable bitumen/polymer compositions which are stable on storage at high temperature, that is to say, according to the invention, up to temperatures which may reach values of the order of 260.degree. C. The invention also relates to a process for the preparation of such compositions and equally concerns the application of these compositions to the production of bitumen/polymer binders which may be used to make coatings and especially road coatings.
2. Background Art
The crosslinking, via sulphur, of unsaturated elastomers, especially of copolymers of styrene and a conjugated diene such as butadiene or isoprene, in bitumens leads to bitumen/polymer compositions which possess enhanced stability and excellent physico-mechanical characteristics and which may be used to make various coatings, especially road surfacings, mixes or alternatively leaktight coatings, having enhanced characteristics compared with the coatings obtained from bitumens alone.
The preparation of bitumen/polymer compositions of the abovementioned type, for which the elastomer which is crosslinkable with sulphur is a copolymer of styrene and a conjugated diene, is described in particular in the citations FR-A-2,376,188, (U.S. Pat. No. 4,145,322), FR-A-2,528,439, (U.S. Pat. No. 4,554,313), and EP-A-0,360,656 (U.S. Pat. No. 5,508,112).
The bitumen/polymer compositions of the abovementioned type, from which bitumen/polymer binders are produced for making coatings, especially road coatings, are prepared in practice at polymer contents below a threshold which may range from about 3% to 6% by weight of bitumen depending on the nature and the molecular weight of the polymer, on the one hand, and the quality of the bitumen, on the other hand, gelling of the bitumen/polymer composition which is observed fairly frequently during the preparation of the said composition or while it is stored, occurs as soon as the polymer content of this composition exceeds the abovementioned threshold. It is thus difficult, in practice, to produce non-gellable bitumen/polymer compositions with a high polymer content, which would act as bitumen/polymer concentrates, and are more economical to prepare and to transport than bitumen/polymer compositions with a lower polymer content, and which could be diluted at the time of use, by addition of bitumen, in order to obtain the corresponding bitumen/polymer binders with a lower polymer content which are usually used to make coatings.
SUMMARY OF THE INVENTION
The invention makes it possible to overcome the abovementioned drawbacks by proposing bitumen/polymer compositions of the type including a bitumen and an elastomer crosslinked with sulphur, which are non-gellable, stable on storage at high temperature, that is to say, according to the invention, up to temperatures of the order of 260.degree. C., and are pumpable by means of conventional systems for pumping molten bitumens and which may readily be diluted, if need be, with bitumen in order to produce the bitumen/polymer binders usually used to make coatings and especially road coatings.
The bitumen/polymer compositions according to the invention are of the type consisting of a homogeneous mass formed of a bituminous matrix consisting of a bitumen or of a mixture of bitumens and in which is uniformly distributed an elastomer crosslinked with sulphur, in an amount between 3% and 30% and preferably between 5% and 25% of the weight of the bituminous matrix, and they are characterized in that an adjuvant, acting especially as an anti-gelling agent, is also present in the bituminous matrix in an amount between 0.1% and 5% and preferably between 0.2% and 3% of the weight of the said matrix, the said adjuvant consisting of one or more compounds of formula R--X, in which R is a monovalent C.sub.2 to C.sub.50 and more especially C.sub.2 to C.sub.40 organic radical and X denotes a functional group chosen from ##STR1## wherein Y representing a hydrogen atom or a radical R.
DESCRIPTION OF THE PRE
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Germanaud Laurent
Phung Trung Kiet
Planche Jean-Pascal
Elf Antar France
Szekely Peter A.
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