Process for the preparation of bitumen-polymer composition

A process is provided for the preparation of bitumen-polymer compositions wherein bitumen is mixed at a composition between 100.degree. C. and 230.degree. C. with a block copolymer of styrene and a conjugated diene and a coupling agent containing a sulphur-donor compound for a duration of at least 10 minutes. The coupling agent is comprised of an elementary sulphur vulcanization agent and at least one sulphur-donor vulcanization accelerator from among morpholine disulphide, N,N'-disulphide of caprolactam and thiuram polysulphides.

The invention concerns a process for the preparation of bitumen-polymer 
compositions. It also refers to the application of the compositions 
obtained to the preparation of coatings and in particular of superficial 
road coatings, coverings or also calking coverings and likewise refers to 
a mother solution of polymer which can be used for the obtention of said 
compositions. 
It is known to use bituminous compositions as coatings of different 
surfaces and in particular as superficial road facings provided said 
compositions possess a certain number of essential mechanical qualities. 
In practice these mechanical qualities are assessed by determining by 
standardized tests a series of mechanical characteristics of which those 
most used are the following: 
softening point expressed in .degree.C. and determined by the Ball and Ring 
test defined by the standard NFT 66 008, 
brittleness point or Fraass point expressed in .degree.C. and determined 
according to the standard IP 80/53, 
penetration expressed in 1/10 of mm and determined acording to the standard 
NFT 66 004, 
rheologic characteristics under traction determined according to the 
standard NFT 46 002 and including the magnitudes: 
constraint at the threshold .sigma..sub.s in bars 
elongation at the threshold .epsilon..sub.s in % 
constraint to the rupture .sigma..sub.r in bars 
elongation at the rupture .epsilon..sub.r in %. 
In general, the conventional bitumens do not simultaneously have the 
combination of qualities required and it has been known for a long time 
that the addition of various polymers to these conventional bitumens makes 
it possible favorably to modify the mechanical properties of the latter 
and to form bitumen-polymer compositions having improved mechanical 
qualities in comparison to those of bitumens alone. 
The polymers apt to be added to bitumens are most often elastomers such as 
polyisoprene, butylic rubber, polybutene, polyisobutene, ethylene/acetate 
vinyl copolymers, polymethacrylate, polychloroprene, 
ethylene/propylene/diene terpolymer (EDPM), polynorbornene, or also 
statistic or sequenced copolymers of styrene and of a conjugated diene. 
Among the polymers added to bitumens, the statistic or sequenced copolymers 
of styrene and of a conjugated diene, specially of styrene and of 
butadiene or of styrene and isoprene, are particularly effective since 
they dissolve very easily in the bitumens and impart to them excellent 
mechanical and dynamic properties, specially very good viscoelastic 
properties. 
It is also known that the stability of the bitumen-polymer compositions can 
be improved by chemical coupling of the polymer with the bitumen, this 
improvement also making it possible to enlarge the field of use of the 
bitumen-polymer compositions. 
Bitumen-polymer compositions for which a statistic or sequenced copolymer 
of styrene or of a conjugated diene such as butadiene or isoprene is 
coupled with bitumen can be prepared by using processes described in the 
citations FR-A-2376188; FR-A-2429241 and FR-A-2528439. In these processes, 
said copolymer and a source of sulphur are incorporated into the bitumen, 
operating between 130.degree. C. and 230.degree. C. and under stirring, 
the mixture thus formed is then maintained under stirring and at a 
temperature between 130.degree. C. and 230.degree. C. for at least 15 
minutes. The source of sulphur consists of chemically non-bonded sulphur 
(FR-A-2376188 and FR-A-2429241) or of a polysulphide (FR-A-2528439) and 
the copolymer and the source of sulphur are incorporated into the bitumen 
either by direct addition of said ingredients to the bitumen (FR-A-2376188 
and FR-A-2528439) or by first preparing a mother solution of the copolymer 
and of the source of sulphur in a hydrocarbonated oil, then adding said 
mother solution to the bitumen (FR-A-2429241 and FR,A-2528439). 
It has now been found that it would be possible substantially further to 
improve the mechanical characteristics and the stability of the 
bitumen-polymer compositions for which a sequenced copolymer of styrene 
and of a conjugated diene, especially butadiene and isoprene, is coupled 
with bitumen under the action of a coupling agent playing the part of 
sulphur donor, if said coupling agent contained at least one accelerator 
of vulcanization directly playing the part of sulphur donor or completing 
the action of the latter. In particular the static mechanical 
characteristics specially determined by traction test are improved at low 
temperature and are preserved to a large extent after simulated aging. 
This preservation of characteristics constitutes a sign of stability of 
the quality of the bitumen-polymer compositions which are most often 
prepared by batch and therefore stored at high temperature for a more or 
less long period prior to being used. 
Therefore the object of the invention is a process for the preparation of 
bitumen-polymer compositions wherein, at a temperature comprised between 
100.degree. C. and 230.degree. C., there is prepared a mixture of bitumen 
with a sequenced copolymer of styrene and of a conjugated diene used in a 
quantity of from 0.5 to 15% by weight of bitumen and a coupling agent 
containing a sulphur-donor compound, and the mixture obtained is kept 
within said temperature range and under stirring for a duration of at 
least 10 minutes, said process being characterized in that the coupling 
agent is selected from among the products M that contain, by weight, from 
1% to 100% of a component A consisting of one or more accelerators of 
vulcanization donors of sulphur and from 99% to 0% of a component B 
consisting of one or more vulcanization agents selected among the 
elementary sulphur and the polysulphides of hydrocarbyl and the products N 
which contain a component C consisting of one or more vulcanization 
accelerators non-donors of sulphur, and a product M or a product D, said 
product D consisting of a component B containing at least one hydrocarbyl 
polysulphide and eventually elementary sulphur, the weight proportion of 
the component C to the product M or to the product D being from 0.01 to 1, 
preferably from 0.05 to 0.5 and the products K formed of elementary 
sulphur and of a component E which consists of a component C in which at 
least one of the accelerators non-donors of sulphur is selected from the 
group formed by the benzothiazolesulphenamides, the metallic 
dithiocarbamates and the thiuram monosulphides, the proportion by weight 
of the component E to the elementary sulphur bein from 0.1 to 1, 
preferably from 0.05 to 0.5, said coupling agent being used in a 
proportion adequate to furnish a quantity of sulphur repesenting, by 
weight, from 0.5 to 10% and more particularly from 1 to 8% of the 
copolymer used to produce the bitumen-polymer composition. 
In particular the products M from which can be selected the coupling agent 
contain, by weight, from 10% to 100% of the component A and from 90 to 0% 
of the component B. 
The vulcanization accelerators donors of sulphur which can be used to form 
the component A of the product M can be selected in particular from the 
thiuram polysulphide of the general formula 
##STR1## 
wherein the R's, identical or different, represent each a hydrocarbon 
radical in C.sub.1 to C.sub.12 and preferably in C.sub.1 to C.sub.8, 
especially an alkyl, cycloalkyl, or aryl radical, or two radicals affixed 
to the same nitrogen atom are interbonded to form a hydrocarbon bivalent 
radical in C.sub.2 to C.sub.8 and x is a number going from 2 to 8. As 
examples of said vulcanization accelerators, there can be especially cited 
the bisulphide compounds of dipentamethylene thiuram, dipentamethylene 
tetrasulphide thiuram, dipentamethylene-thiuram hexasulphide, 
tetrabutylthiuram bisulphide, tetraethylthiuram bisulphide and 
tetramethylthiuram bisulphide. 
As other examples of vulcanization accelerators donors of sulphur which can 
be used to form the component A of the product M there can also be cited 
the alkyl phenol disulphides and the disulphides such as morpholine 
disulphide and N,N'-disulphide of caprolactams. 
The vulcanization accelerators non-donors of sulphur which can be used to 
form the component C of the product N can advantageously be 
sulphur-containing compounds selected from the benzothiazolesulphenamides 
and the dithiocarbamates of the general formula (I) 
##STR2## 
wherein the R's, identical or different, have the meaning given above, Y 
represents a metal and q designates the valence of Y and the thiuram 
monosulphides of the general formula (II) 
##STR3## 
wherein the R's, identical or different, have the meaning given above. 
Examples of vulcanization accelerators of the type of 
benzothiazolesulphenamides can be such as 
2-benzothiazole-diethylsulphenamide, 
2-benzothiazole-pentamethylenesulphenamide, 
2-benzothiazole-cyclohexylsulphenamide, N-oxydiethylene 
2-benzothiazolesulphenamide, N-oxydiethylene 
2-benzothiazole-thiosulphenamide, 
2-benzothiazole-dicyclohexylsulphenamide, 2-benzothiazolediisopropyl 
sulphenamide, 2-benzothiazoletertiobutyl sulphenamide, 
N-oxydiethylenethiocarbamyl N'-oxydiethylene sulphenamide. 
Among the vulcanization accelerators of the type of dithiocarbamates of the 
general formula (I), there can be particularly cited the bismuth 
dimethyldithiocarbamate cadmium diamyldithiocarbamate, cadmium 
diethyldithiocarbamate, copper dimethyldithiocarbamate, zinc 
dibutyldithiocarbamate, lead diamyldithiocarbamate, lead 
dimethyldithiocarbamate, lead pentamethylenedithiocarbamate, selenium 
dimethyldithiocarbamate, tellurium diethyldithiocarbamate, zinc 
diamyldithiocarbamate, zinc dibenzyldithiocarbamate, zinc 
diethyldithiocarbamate and zinc pentamethylenedithiocarbamate. 
As examples of thiuram monosulphides corresponding to the general formula 
(II), there can be cited compounds such as dipentamethylenethiuram 
monosulphide, tetrabutylthiuram monosulphide, tetraethylthiuram 
monosulphide and tetramethylthiuram monosulphide. 
The above vulcanization accelerators non-donors of sulphur can likewise be 
those among which are selected the vulcanization accelerator or 
accelerators of the group of benzothiazole sulphenamides, metallic 
dithiocarbamates and thiuram monosulphides which are necessarily present 
in the component E of the product K. 
Other vulcanization accelerators non-donors of sulphur which do not belong 
to the families defined above can likewise be used to form the component C 
of the product N or eventually can be present in the component E of the 
product K. Such vulcanization accelerators can be mercaptobenzothiazole, 
benzothiazolethiolate of a metal such as zinc, sodium, copper, 
benzothiazyl disulphide, N,N'-diethylthiocarbamyl benzothiazyl sulphide, 
diphenyl-1,3 guanidine, diorthotolylguanidine and zinc oxide, it being 
possible to use the later compound eventually in the presence of fatty 
acids of the type stearic acid, ethylcaproic acid, lauric acid. 
Among the different mixtures capable of constituting coupling agents 
according to the invention, there are preferred those that result in a 
quick vulcanization and that limit the risk of prevulcanization. 
As indicated above, the component B of the coupling agent consists of one 
or more vulcanization agents selected among elementary sulphur and the 
hydrocarbyl polysulphides. 
The sulphur used is advantageously sulphur in bloom, preferably the 
orthorhombic crystallized sulphur known by the name of alpha shlphur. In 
particular, the component B of the product M or the elementary sulphur 
associated with the component B to form the product K consists of 
orthorhombic crystallized sulphur. 
The hydrocarbyl polysulphides which can be used as vulcanization agents in 
the component B of the product M or in the product D have the general 
formula 
##STR4## 
wherein R.sub.1 and R.sub.2 designate each a saturated or unsaturated 
monovalent hydrocarbon radical in C.sub.1 to C.sub.20 or are interbonded 
to constitute a bivalent hydrocarbon radical in C.sub.2 to C.sub.20, 
saturated or not, forming a cycle with the other groups of atoms 
associated in the formula, R.sub.3 is a saturated or unsaturated bivalent 
hydrocarbon radical in C.sub.1 to C.sub.20, --(S).sub.m 's represents 
bivalent groups each one formed of m sulphur atoms, m's can differ from 
one of said groups to the other and designate integers going from 1 to 6 
with at least one of the m's being equal to or more than 2, r represents 
an integer assuming values from zero to 10. 
In the above cited formula., the monovalent hydrocarbon radicals R.sub.1 
and R.sub.2 in C.sub.1 to C.sub.20 and the bivalent hydrocarbon radical 
R.sub.3 in C.sub.1 to C.sub.20 are specially selected among the aliphatic, 
alicyclic or aromatic radicals. When the radicals R.sub.1 and R.sub.2 are 
interbonded to constitute a bivalent hydrocarbon radical in C.sub.1 to 
C.sub.20 forming a cycle with the other atom groups associated in the 
formula, said bivalent radical is similar to the radical R and can 
likewise be of the aliphatic, alicyclic or aromatic type. The radicals 
R.sub.1 and R.sub.2 in particular are identical and selected among the 
alkyl radicals in C.sub.1 to C.sub.20, for example, ethyl, propyl, hexyl, 
octyl, nonyl, decyl, linear dodecyl, tertio-dodecyl, hexadecyl, octadecyl 
and the cycloalkyl and aryl radicals in C.sub.6 to C.sub.20, especially 
benzyl, phenyl, tolyl, cyclohexyl, while the radical R.sub.3 or the 
bivalent radical formed by the union of R.sub.1 and R.sub.2 are selected 
among the alkylene radicals in C.sub.1 to C.sub.20 or the cycloalkylene 
or arylene radicals, especially phenylene, tolylene and cyclohexylene in 
C.sub.6 to C.sub.20. 
Polysulphides that can be used according to the invention are, in 
particular, those defined by the formula 
EQU R.sub.1 --(S).sub.n --R.sub.2 
wherein R.sub.1 and R.sub.2 designate each a monovalent hydrocarbon 
radical, saturated or unsaturated, in C.sub.1 to C.sub.20, or are 
interbonded to form a bivalent radical R.sub.3 in C.sub.1 to C.sub.20, 
R.sub.1, R.sub.2 and R.sub.3 have the above meanings,--(S).sub.n 
--represents a bivalent group formed by a chain of n sulphur atoms, and n 
being an integer from 2 to 6. 
The preferred polysulphides correspond to the general formula 
EQU R.sub.4 --(S).sub.p --R.sub.4 
wherein R.sub.4 designates an alkyl radical in C.sub.6 to C.sub.16 and 
--(S).sub.p --represents a bivalent group formed by a chain of sulphine 
atoms, p being an integer from 2 to 5. Examples of such polysulphides are 
in particular dihexyl bisulphide, dioctyl bisulphide, didodecyl 
bisulphide, diterdiododecyl bisulphide, dihexadecyl bisulphide, dihexyl 
trisulphide, dioctyl trisulphide, dinonyl trisulphide, ditertiododecyl 
trisulphide, dihexadecyl trisulphide, dihexyl tetrasulphide, dioctyl 
tetrasulphide, diononyl tetrasulphide, ditertiododecyl tetrasulphide, 
dihexadecyl tetra sulphide, dihexyl pentasulphide, dioctyl pentasulphide, 
dinonyl pentasulphide, ditertiododecyl pentasulphide and dihexadecyl 
pentasulphide. 
Other polysulphides that can be used according to the invention are, for 
example, such as diphenyl trisulphide, dibenzyl trisulphide, diphenyl 
tetrasulphide, orthotolyltetrasulphide, dibenzyl tetrasulphide, dibenzyl 
pentasulphide, diallyl pentasulphide and tetramethyl-tetrathiane. 
Bitumen, which constitutes the major portion of the bitumen-polymer 
compositions according to the invention, is selected among the different 
bitumens having a penetration, defined according to the standard NFT 
66004, comprised of between 5 and 500, preferably between 20 and 400. Such 
bitumens can be, in particular, bitumens of direct distillation or of 
distillation under reduced pressure, or also blown or semi-blown bitumens 
having a penetration comprised within the above-mentioned ranges. 
The copolymer of styrene and of a conjugated diene used in the preparation 
of the bitumen-polymer composition is advantageously selected among the 
sequenced copolymers of styrene and butadiene, of styrene and isoprene, of 
styrene and chloroprene, of styrene and carboxylated butadiene and of 
styrene and carboxylated isoprene. The copolymer of styrene and of 
conjugated diene, particularly each one of the above-cited copolymers, has 
a content by weight of styrene, preferably from about 15% to 40%. The 
average viscosimetric molecular weight of the copolymer of styrene and of 
conjugated diene and, in particular, that of the copolymers mentioned 
above, can advantageously be comprised of between 30,000 and 300,000, 
preferably between 70,000 and 200,000. 
The copolymer of styrene and conjugated diene is selected preferably among 
the bi- or tri-sequenced copolymers of styrene and butadiene, styrene and 
isoprene, styrene and carboxylated butadiene, styrene and carboxylated 
isoprene, having contents of styrene and molecular weights falling within 
the above-defined ranges. 
The preferred amount of copolymer added to the bitumen is comprised of 
between 0.7 and 10% by weight of the bitumen. 
In a preferred embodiment of the process according to the invention, the 
copolymer and the coupling agent are incorporated in the bitumen in the 
form of a mother solution of said two products in a solvent consisting of 
a bydrocarbon oil which has a range of distillation at atmospheric 
pressure, determined according to the standard ASTM D 86-87, comprised of 
between 100.degree. C. and 450.degree. C., more particularly, between 
150.degree. C. and 370.degree. C. 
Said hydrocarbon oil, which can especially be a petroleum fraction of 
aromatic nature, a petroleum fraction of naphtheno-paraffinic nature, a 
petroleum fraction of paraffinic nature, a petroleum fraction of 
naphtheno-aromatic nature, a coal-tar oil, or also an oil of vegetable 
origin, is "heavy" enough to limit the evaporation at the moment of adding 
the mother solution to the bitumen and at the same time, "light" enough to 
be eliminated at the maximum after scattering of the bitumen-polymer 
composition that contains it, so as to recover the same mechanical 
properties it would have had after scattering hot the bitumen-polymer 
composition prepared without making use of the technique of the mother 
solution. 
The mother solution is prepared by putting into contact the ingredients 
that..compose it, namely, hydrocarbon oil serving as the solvent, the 
copolymer and coupling agent, under stirring, at temperatures comprised of 
between 20.degree. and 170.degree. C. and more particularly, between 
40.degree. and 120.degree. C. for a sufficient period of time, for 
example, for about 30 minutes to about 90 minutes, for obtaining a 
complete dissolution of the copolymer and of the coupling agent in the 
hydrocarbon oil. 
The respective concentrations of the copolymer and of the coupling agent in 
the mother solution can vary quite widely, especially depending on the 
nature of the hydrocarbon oil used for dissolving the copolymer and the 
coupling agent. The respective quantities of copolymer and of the coupling 
agent can thus advantageously represent from 5% to 40%, and from 0.02 to 
15% of the weight of hydrocarbon oil. A preferred mother solution 
contains, counted by weight of hydrocarbon oil used as the solvent, from 
10 to 35% of copolymer and from 0.1 to 5% of coupling agent. 
When the compositions, according to the invention, are directly formed from 
the ingredients of bitumen, copolymer and coupling agent, the work is 
preferably carried out by first bringing into contact the copolymer with 
the bitumen in the proportions selected, at a temperature comprised of 
between 100.degree. C. and 230.degree. C. and while stirring for a 
sufficient period of time, generally on the order of a few dozen minutes 
to a few hours, to form a homogeneous mixture, then the coupling agent is 
added to the mixture obtained, and the whole is kept under stirring at a 
temperature comprised of between 100.degree. C. and 230.degree. C. 
corresponding, for example, to the temperature existing when the copolymer 
is put into contact with the bitumen for a period of time at least equal 
to 10 minutes and generally from about 10 to 90 minutes to allow the 
coupling agent to release the radicalaire sulphur and to allow the 
radicalaire sulphur thus produced to initiate, on one hand, the grafting 
of the copolymer on the bitumen and, on the other hand, the cross-linking 
of the chains of said copolymer with each other. 
The quantities of copolymer put into contact with the bitumen and of the 
coupling agent added then to the homogeneous mixture of bitumen and of 
said copolymers are selected to be comprised within the ranges defined 
above for these quantities. 
For preparing the bitumen-polymer compositions according to the invention 
by making use of the technique of the mother solution, the mother solution 
of copolymer and coupling agent is mixed with the bitumen, working at a 
temperature comprised of between 100.degree. C. and 230.degree. C. under 
stirring, this being effected, by example, by adding the mother solution 
to the bitumen kept under stirring at the temperature between 100.degree. 
C. and 230.degree. C. the resulting mixture is then maintained under 
stirring at a temperature comprised of between 100.degree. C. and 
230.degree. C., for example, at the temperature used for the admixture of 
the mother solution to the bitumen, for a period at least equal to 10 
minutes, and generally from about 10 to 90 minutes, to allow by the 
expedient of the coupling agent the grafting of the copolymer on the 
bitumen alphaltenes and the cross-linking with each other of the chains of 
said copolymer. 
The quantity of mother solution admixed to the bitumen is selected for 
furnishing in relation to the bitumen, the desired quantities of copolymer 
and of coupling agent, said quantities being within the guides defined 
above. 
A particularly preferred embodiment for the preparation of bitumen-polymer 
compositions according to the invention by the technique of the mother 
solution consists of bringing into contact, at a temperature comprised of 
between 100.degree. C. and 230.degree. C. while stirring, from 80 to 95% 
by weight of the bitumen with from 20 to 5% by weight of the mother 
solution, the latter containing by weight hydrocarbon oil serving as a 
solvent, from 10 to 35% of copolymer of styrene and of conjugated diene 
and from 0.1 to 5% of coupling agent, then keeping the mixture thus 
obtained under stirring at a temperature comprised of between 100.degree. 
C. and 230.degree. C., preferably at the temperature used for bringing 
into contact the bitumen with the mother solution, for a period at least 
equal to 10 minutes, and preferably comprised of between 10 and 60 
minutes. 
The bitumen-polymer compositions obtained by the process according to the 
invention can be used for making different coatings and in particular, 
superficial road coatings. It is especially for this use that the 
bitumen-polymer compositions of the invention prepared by the technique of 
the mother solution are quite particularly adapted, since they can be 
directly utilized by the classical means of spreading. 
The invention is illustrated by the examples that follow, that are not 
limiting. 
The rheologic and mechanical, characteristics of the bitumens or of the 
bitumen-polymer compositions referred to in these examples are those 
defined above, namely, penetration, softening point, Fraas point and 
rheologic characteristics by traction.

EXAMPLE 1 
Preparation of a control bitumen-polymer composition by direct 
incorporation of the copolymer and of the coupling agent into the bitumen. 
Working at 170.degree. C. while stirring, 1,000 portions by weight of a 
bitumen of direct distillation having a penetration of 82, a softening 
point Ball and Ring of 48.degree. C., a Fraas point equal to -18.5.degree. 
C. and a viscosity at 160.degree. C. of 1.7.times.10.sup.-4 m.sup.2 /s are 
mixed with 31 portions by weight of a bi-sequenced copolymer of styrene 
and of butadiene having a viscosimetric average molecular weight equal to 
about 75,000 and containing 25% by weight of styrene. 
A homogeneous mass was obtained after 3 hours and 10 minutes of mixing 
while stirring. 
To this mess kept at 170.degree. C. there was then added 1 portion by 
weight of crystallized sulphur and the whole continued to be stirred for 
60 minutes to form the bitumen-polymer composition. 
In Table I, there is given the main characteristics of the bitumen-polymer 
composition thus obtained before and after being subjected to the aging 
test called "Rolling Film Oven Test" defined in standard ASTM D 2872. The 
bitumen-polymer compositions before and after the aging test are 
respectively designated as "Product Ia1" and "Product Ia2". 
Table I likewise gives the corresponding characteristics of the starting 
bitumen before and after the aging test (respectively "Product Ib1" and 
"Product Ib2"). 
Referring to the values given in Table I, it can be seen that the use of a 
coupling agent constituted by crystallized sulphur results in a 
bitumen-polymer composition the elastomeric characteristics of which 
differentiate it clearly from the bitumen (compare the results of the 
traction test). Besides, the stability with regard to aging of the 
bitumen-polymer composition is improved in comparison to that observed for 
the pure bitumen. 
TABLE I 
__________________________________________________________________________ 
PENETRATION 
Softening 
Fraas 
TRACTION TEST 
Characteristics 
at 25.degree. C. 
POINT POINT 
TEMP. 
SPEED 
.sigma..sub.s 
.sigma..sub.r 
.epsilon..sub.s 
.epsilon..sub.r 
Product (1/10 mm) 
B & A (.degree.C.) 
(.degree.C.) 
(.degree.C.) 
mm/mn 
bars 
bars 
% % 
__________________________________________________________________________ 
I a 1 67 57 -19.5 
20 500 2.3 
0.5 
23 
&gt;900 
5 500 20 5.6 
15 
330 
I a 2 49 59 -17 20 500 4.4 
1.8 
20 
&gt;900 
5 500 2.5 
9.1 
13 
180 
I b 1 82 48 -18.5 
20 500 1.2 
0 15 
&gt;900 
5 500 FRAGILE 
I b 2 51 50 -15 5 500 1.8 
0 15 
&gt;900 
5 500 FRAGILE 
__________________________________________________________________________ 
EXAMPLE 2 
Preparation of a bitumen-polymer composition according to the invention by 
direct incorporation of the copolymer and the coupling agent into the 
bitumen. 
The work is carried out as described in Example 1, but by using by way of 
coupling agent, a mixture of 0.8 portion by weight of crystallized sulphur 
and 0.2 portion by weight of a sulphur-donor vulcanization accelerator 
consisting of tetramethylthiuram bisulphide. 
In Table II, there is given for the bitumen-polymer compositions obtained 
in Examples 1 and 2, characteristics analogous to those appearing in Table 
I. The same signs symbolize the characteristics corresponding to the 
bitumen-polymer composition before and after the aging test. 
As it appears from the results shown in Table II, the use of a 
sulphur-donor vulcanization accelerator mixed with the crystallized 
sulphur to constitute the coupling agent leads to the obtention of a 
bitumen-polymer composition having elastomeric characteristics 
substantially improved, especially at low temperatures, compared to those 
observed for the control bitumen-polymer composition prepared by using a 
coupling agent consisting only of crystallized sulphur. Besides, the 
stability with respect to aging of the bitumen-polymer composition 
according to the invention is clearly improved in comparison to that of 
the control bitumen-polymer composition. 
TABLE II 
__________________________________________________________________________ 
PENETRATION 
Softening 
Fraas 
TRACTION TEST 
Characteristics 
at 25.degree. C. 
POINT POINT 
TEMP. 
SPEED 
.sigma..sub.s 
.sigma..sub.r 
.epsilon..sub.s 
.epsilon..sub.r 
Product (1/10 mm) 
B & A (.degree.C.) 
(.degree.C.) 
(.degree.C.) 
mm/mn 
bars 
bars 
% % 
__________________________________________________________________________ 
I a 1 67 57 -19.5 
20 500 2.3 
0.5 
23 
&gt;900 
5 500 20 5.6 
15 
330 
I a 2 49 59 -17 20 500 4.4 
1.8 
20 
&gt;900 
5 500 25 9.1 
13 
180 
II a 1 64 56 -23 20 500 3.1 
1.3 
25 
&gt;900 
5 500 23 9.5 
22 
&gt;900 
II a 2 44 63 -18 20 500 3.3 
1.3 
20 
&gt;900 
5 500 22 9.8 
18 
550 
__________________________________________________________________________ 
EXAMPLES 3-7 
Preparations of bitumen-polymer compositions according to the invention by 
direct incorporation of the copolymer and of the coupling agent into the 
bitumen. 
The work was carried out as described in Example 2, but with certain 
variations defined herebelow, the other operating conditions being those 
of Example 2. 
In Example 3, the coupling agent was constituted by a mixture of 0.2 
portion by weight of tetramethylthiuram bisulphide and 0.7 portion by 
weight of crystallized sulphur and the temperature was equal to 
160.degree. C. 
In Example 4, the coupling agent was formed by a mixture of 0.2 portion by 
weight of a vulcanization accelerator not donor of sulphur consisting of 
2-benzothiazole-dicyclohexylsulphenamide and 0.8 portion by weight of 
crystallized sulphur and the reaction temperature was equal to 180.degree. 
C. 
In Example 5, the coupling agent was constituted by a mixture of 0.15 
portion by weight of a sulphur-donor vulcanization accelerator consisting 
of morpholine bisulphide and 0.75 portion by weight of crystallized 
sulphur, the reaction being conducted at 140.degree. C. 
In Example 6, the coupling agent was formed by a mixture of 0.2 portion by 
weight of two vulcanization accelerators not donors of sulphur, namely, 
2-benzothiazole diisopropylsulphenamide and zinc dimethyldithiocarbamate 
used in equal gravimetric quantities, and 0.8 portion by weight of 
crystallized sulphur, the reaction temperature being kept at 140.degree. 
C. 
In Example 7, the coupling agent was constituted by a mixture of 2 portions 
by weight of a sulphur-donor vulcanization accelerator consisting of 
dipentamethylenethiuram tetrasulphide and of 0.6 portion by weight of a 
vulcanization accelerator not donor of sulphur consisting of zinc oxide, 
the coupling reaction being carried out at 140.degree. C. 
In Table III, there is given the characteristics of the bitumen-polymer 
compositions thus obtained before and after having been subjected to the 
aging test. 
The bitumen-polymer compositions prior to aging have been designated by 
"Product P.a.1" while the corresponding bitumen-polymer compositions after 
aging have been designated by "Product P.a.2", P representing the number 
of the example in Roman numerals. 
TABLE III 
__________________________________________________________________________ 
PENETRATION 
Softening 
Fraas 
TRACTION TEST 
Characteristics 
at 25.degree. C. 
POINT POINT 
TEMP. 
SPEED 
.sigma..sub.s 
.sigma..sub.r 
.epsilon..sub.s 
.epsilon..sub.r 
Product (1/10 mm) 
B & A (.degree.C.) 
(.degree.C.) 
(.degree.C.) 
mm/mn 
bars 
bars 
% % 
__________________________________________________________________________ 
III a 1 67 58 -26 20 500 2.1 
0.7 
23 
&gt;900 
5 500 18 6.8 
22 
&gt;900 
III a 2 40 65 -19 20 500 4.0 
2.0 
29 
&gt;900 
5 500 21 9.1 
27 
340 
IV a 1 66 57 -23 20 500 2.3 
0.4 
18 
&gt;900 
5 500 19 5.1 
15 
&gt;900 
IV a 2 43 62 -18 20 500 4.2 
1.9 
28 
&gt;900 
5 500 23 9.4 
25 
380 
V.a.1 64 53 -20 20 500 2.5 
0.7 
25 
&gt;900 
5 500 21 6.2 
20 
&gt;900 
V.a.2 43 65 -18 20 500 4.4 
1.9 
29 
&gt;900 
5 500 24 9.3 
22 
220 
VI.a.1 59 56 -16 20 500 2.6 
1 21 
&gt;900 
5 500 22 7 20 
&gt;900 
VI.a.2 41 63 -14 20 500 4.5 
2 29 
&gt;900 
5 500 30 9 15 
210 
VII.a.1 60 57 -22 20 500 7.7 
1.3 
28 
&gt;900 
5 500 16 4.6 
23 
&gt;900 
VII.a.2 42 64 -17 20 500 4.7 
1.5 
26 
&gt;900 
5 500 23 9.9 
25 
410 
__________________________________________________________________________ 
EXAMPLE 8 
Preparation of a control bitumen-polymer composition by the method of the 
mother solution. 
(a) Preparation of the Mother Solution: 
The work was carried out in a stainless steel reactor provided with a 
stirrer and with a double jacket capable of being trasversed by a 
heat-conducting fluid. 
The hydrocarbon oil used as the solvent to form the mother solution was a 
petroleum fraction of naphtheno/aromatic nature having the following 
characteristics: 
initial distillation point ASTM equal to 176.degree. C. 
final distillation point ASTM equal to 352.degree. C. (measured according 
to the standard ASTM D 86-67) 
flashing point (Luchaire standard NF T 60103) of 79.degree. C. 
volume weight (standard ASTM D 1657-64) equal to 0.956 
In the reactor, there was introduced 233 parts by weight of the petroleum 
fraction, which was heated while stirring, to a temperature of about 
100.degree. C. by circulating a hot fluid in the double jacket of the 
reactor. 
While maintaining said temperature and stirring, there was then introduced 
in the reactor, 2 portions by weight of crystallized sulphur and 54 
portions by weight of a powder, made anti-caking by 2% by weight of 
silica, of a di-sequenced copolymer of styrene and of butadiene 
containing, by weight, 25% styrene and having a viscosimetric average 
molecular weight of about 75,000. 
After stirring for one hour at a temperature of about 100.degree. C. there 
was obtained a homogeneous and fluid solution at ordinary temperature 
characterized by the values of kinematic viscosity that follow: 
kinematic viscosity measured at 50.degree. C. : 12.10.times.10.sup.-4 
m.sup.2 /s 
kinematic viscosity measured at 100.degree. C.: 2.92.times.10.sup.-4 
m.sup.2 /s 
This solution constituted the mother solution for the preparation of the 
bitumen-polymer composition. 
(b) Preparation of the Bitumen-Polymer Composition: 
In a vat equipped with stirrers and provided with steam heaters, there were 
pumped at 170.degree. C. 1,700 portions of a bitumen of direct 
distillation having the initial physical properties: 
softening point (Test B & A) : 48.degree. C. 
Fraass point: -18.5.degree. C. 
penetration: 82 1/10 mm 
kinematic viscosity at 160.degree. C. : 1.70.times.10.sup.-4 m.sup.2 /s 
To the contents of the vat, kept at 170.degree. C. under stirring, there 
was then added 300 portions of the mother solution prepared as described 
above. 
After 30 minutes stirring at the temperature of 170.degree. C., there was 
obtained a fluid bitumen-polymer composition having at 160.degree. C., a 
dynamic viscosity equal to 0.098 Pa.s., that is to say, a viscosity 
comparable to that of a bitumen having a penetration within the range of 
180-220 and capable of being directly charged in a classical scatterer of 
medium pressure. 
In Table IV, there is given the properties of the bitumen-polymer 
composition thus obtained before and after being subjected to a thermal 
treatment consisting of bringing to 160.degree. C. in an oven, an airtight 
metal vessel containing the bitumen-polymer composition and in maintaining 
said vessel at said temperature for 60 days, this test allowing to 
simulate the evolution of the product during a long period of storage. The 
bitumen-polymer composition is designated by "Product VIII.a.1" prior to 
thermal treatment and by "Product VIII.a.2" after thermal treatment. 
Table IV likewise shows by way of comparison before and after said thermal 
treatment the corresponding characteristics of the starting bitumen, 
liquified by 12% by weight, in relation to the bitumen, of the solvent 
used for constituting the mother solution ("Product VIII.b.1" and "Product 
VIII.b.2", respectively) and of a bitumen-polymer composition prepared in 
a manner similar to the one described in Example 8, but omitting the 
crystallized sulphur ("Product VIII.c.1" and "Product VIII.c.2"). 
In the designation of the product, the "1"s and "2"s define the 
bitumen-polymer compositions respectively before and after the thermal 
treatment. 
TABLE IV 
__________________________________________________________________________ 
Viscosity 
(Rheomat) 
Pseudo 
TRACTION TEST 
Characteristics 
at 160.degree. C. 
Viscosity 
TEMP. 
SPEED 
.sigma..sub.s 
.sigma..sub.r 
.epsilon..sub.s 
.epsilon..sub.r 
Product (Poise) 
(s) (.degree.C.) 
mm/mn 
bars 
bars 
% % 
__________________________________________________________________________ 
VIII a 1 
1.01 100 -10 500 5,6 
1,6 
15 
&gt;900 
VIII a 2 
1.2 114 -10 500 4,1 
2,6 
20 
&gt;900 
VIII b 1 
0.7 60 -10 500 FRAGILE 
VIII b 2 
0.85 80 -10 500 FRAGILE 
VIII.C.1 
0.81 84 -10 500 6.3 
0 15 
300 
VIII.C.2 
0.97 96 -10 500 FRAGILE 
__________________________________________________________________________ 
As it appears from the comparison of the results shown on Table IV, the use 
of crystallized sulphur as the coupling agent in the method that uses the 
mother solution leads to the obtention of a liquified bitumen-polymer 
composition having elastomeric characteristics. After storage at elevated 
temperature, the product gives a residual binder having properties 
approximate to those of the bitumen-polymer composition prior to the 
thermal treatment. 
EXAMPLE 9 
Preparation of the bitumen-polymer composition according to the invention 
by the method of the mother solution. 
The work is carried out as described in Example 8, but forming the mother 
solution from 243.6 portions by weight of the petroleum fraction, 54 
portions by weight of the di-sequenced copolymer of styrene and butadiene 
and of a coupling agent constituted by 0.4 portion by weight of a 
sulphur-donor vulcanization accelerator consisting of tetramethylthiuram 
bisulphide and of 1.5 portions by weight of crystallized sulphur. 
In Table V, there is given for the bitumen-polymer composition obtained, 
characteristics analogous to those given in Table IV for the control 
composition of Example 8, Table V, likewise, including the characteristics 
of the control composition to simplify the comparison. 
The examination of the results given in Table V make evident that the use 
of a coupling agent according to the invention in the method of 
preparation of bitumen-polymer composition that makes use of the mother 
solution leads to the obtention of a bitumen-polymer composition having 
elastomeric characteristics clearly improved, in particular, the 
resistance to rupture .gradient.r, in comparison to those of the control 
bitumen-polymer composition for the preparation of which (Example 8) only 
crystallized sulphur was used as the coupling agent. 
TABLE V 
__________________________________________________________________________ 
Viscosity 
(Rheomat) 
Pseudo 
TRACTION TEST 
Characteristics 
at 160.degree. C. 
Viscosity 
TEMP. 
SPEED 
.sigma..sub.s 
.sigma..sub.r 
.epsilon..sub.s 
.epsilon..sub.r 
Product (Poise) 
(s) (.degree.C.) 
mm/mn 
bars 
bars 
% % 
__________________________________________________________________________ 
VIII a 1 
1.01 100 -10 500 4.6 
1,6 
15 
&gt;900 
VIII a 2 
1.20 114 -10 500 4.1 
2.6 
20 
&gt;900 
IX.a.1 1.21 116 -10 500 4.6 
2.5 
17 
&gt;900 
IX.a.2 1.30 125 -10 500 5.2 
3.4 
22 
&gt;900 
__________________________________________________________________________ 
Besides the stability during storage at elevated temperatures, for example, 
at 160.degree. C. for 2 months, of the bitumen-polymer composition 
according to the invention (Example 9) is very improved in comparison to 
that of the control composition (Example 8), the elastomeric properties of 
the composition according to the invention thus stored (Product IX.a.2) 
being as good as those of the freshly prepared composition (Product 
IX.a.1). 
EXAMPLES 10 and 11 
Preparations of bitumen-polymer compositions according to the invention by 
the method of the mother solution. 
The work is carried out as described in Example 9, but with certain 
variations defined below, the other conditions of operation being the same 
as those of Example 9. 
In Example 10, the vulcanization accelerator present in the coupling agent 
consisted of zinc dimethyldithiocarbamate, a vulcanization accelerator 
that is not sulphur donor. 
In Example 11, the vulcanization accelerator present in the coupling agent 
consisted of tetramethylthiuram monosulphide, a vulcanization accelerator 
that is not sulphur donor. 
In Table VI, there is given the characteristics of the bitumen-polymer 
compositions obtained before and after having been subjected to the test 
of thermal storage defined in Example 8. 
The bitumen-polymer compositions are designated, before and after storage, 
by signs comparable to those used in the preceding examples. 
TABLE VI 
__________________________________________________________________________ 
Viscosity 
(Rheomat) 
Pseudo 
TRACTION TEST 
Characteristics 
at 160.degree. C. 
Viscosity 
TEMP. 
SPEED 
.sigma..sub.s 
.sigma..sub.r 
.epsilon..sub.s 
.epsilon..sub.r 
Product (Poise) 
(s) (.degree.C.) 
mm/mn 
bars 
bars 
% % 
__________________________________________________________________________ 
X.a.1 1.20 112 -10 500 5.7 
2.6 
18 
&gt;900 
X a 2 1.40 131 -10 500 5.2 
3.0 
23 
&gt;900 
XI.a.1 1.16 110 -10 500 6.0 
2.4 
16 
&gt;900 
XI.a.2 1.41 132 -10 500 5.5 
3.4 
21 
&gt;900 
__________________________________________________________________________