Process for the preparation of functionalized...

Details Process for the preparation of functionalized... Process for the preparation of functionalized...

1999-04-12

2001-04-17

Szekely, Peter (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S059000, C524S070000, C524S071000, C525S054500

Reexamination Certificate

active

06218449

ABSTRACT:

BACKGROUND OF THE INVENTION
1) Field of the Invention
The invention relates to a process for the preparation of functionalized elastomer/bitumen compositions. 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° C. and 200° 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 production 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 ring-and-ball softening temperature and the Fraass brittleness point) and mechanical characteristics at low temperatures of use, are not entirely satisfactory.
Provision is made, in the French patent application filed on Oct. 19, 1995 by the Applicant Company under No. 9512276, for a process for the preparation of functionalized elastomer/bitumen compositions exhibiting an expanded plasticity range and improved tensile mechanical characteristics, which process is comparable with the process of the citation U.S. Pat. No. 4,011,184 and is distinguished therefrom by the use of 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 cross-linkings. This functionalization agent is composed of at least one compound chosen from C
3
and greater thiolcarboxylic acids, esters of C
2
and greater thiolcarboxylic acids with monoalcohols and the corresponding disulphides.
SUMMARY OF THE INVENTION
It has now been found that it is possible to prepare polymer/bitumen compositions having physico-mechanical characteristics comparable with those of the polymer/bitumen compositions produced by the process of the abovementioned French patent application by resorting to other functionalization agents composed of polyesters of thiolcarboxylic acids and of polyols or of reaction products of thiolcarboxylic acids or esters with ethylene sulphide.
The subject-matter 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° C. and 230° C. and with stirring for a period of time of at least ten minutes, with, with respect to the weight of the bitumen, between 0.5% and 25%, more particularly between 1% and 15%, of an elastomer and between 0.01% and 6%, more especially between 0.05% and 3%, of a functionalization agent, the said process being characterized in that the functionalization agent is composed of at least one compound chosen from the group composed of:
(i) poly(thiolcarboxylic esters) A corresponding to the formula
(ii) polythioethers B resulting from the reaction of at least one polythiolester A with ethylene sulphide and containing, on average, 0.1 to 20 and more particularly 0.4 to 12 (SCH
2
CH
2
) units per molecule A and
(iii) polythioethers E resulting from the reaction of at least one thiol compound D of formula
 with ethylene sulphide and containing, on average, 0.1 to 20 and more particularly 0.4 to 12 (SCH
2
CH
2
) units per molecule D, with, in these formulae, R denoting a y-valent hydrocarbon radical, which optionally contains oxygen, having a molecular mass at least equal to 28 and which can range up to 20,000 and more particularly up to 12,000, R
1
representing a (t+2)-valent C
1
to C
30
, more especially C
1
to C
12
and very particularly C
1
to C
8
hydrocarbon radical, R
2
representing an (x+t+1)-valent C
1
to C
30
, more especially C
1
to C
12
and very particularly C
1
to C
8
hydrocarbon radical, X denoting a hydrogen atom or a monovalent C
1
to C
12
and more especially C
1
to C
8
hydrocarbon radical R
5
, t representing zero or one, y being an integer ranging from 2 to 10, more especially from 2 to 6 and very particularly from 2 to 4, and x denoting an integer having a value ranging from 1 to 3, preferably equal to 1 or 2, with x+t≦3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The functionalization agent is advantageously chosen from:
(a) poly(thiolcarboxylic esters) A
1
corresponding to the formula
R—[OOC—R
3
—SH]
y
,
(b) polythioethers B
1
resulting from the reaction of at least one polythiolester A
1
with ethylene sulphide and containing, on average, 0.1 to 20 and more particularly 0.4 to 12 (SCH
2
CH
2
) units per molecule A
1
and
(c) polythioethers E
1
resulting from the reaction of at least one thiol compound D
1
of formula
HS—R
4
—(COOX)
x
 with ethylene sulphide and containing, on average, 0.1 to 20 and more particularly 0.4 to 12 (SCH
2
CH
2
) units per molecule D
1
, with, in these formulae, R
3
representing a divalent C
1
to C
12
and more especially C
1
to C
8
hydro—carbon radical, R
4
denoting an (x+1)-valent C
1
to C
12
and more particularly C
1
to C
8
hydrocarbon radical and R, X, y and x having the meanings given above.
The (t+2)-valent, (x+t+1)-valent, divalent, (x+1)-valent and monovalent hydrocarbon radicals R
1
, R
2
, R
3
, R
4
and R
5
respectively can be saturated, linear or branched, C
1
to C
12
, more particularly C
1
to C
8
and very especially C
1
to C
6
aliphatic radicals, unsaturated, linear or branched, C
2
to C
12
, more particularly C
2
to C
8
and very especially C
2
to C
6
aliphatic radicals, C
4
to C
12
, more particularly C
6
to C

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