Method for preparing bitumen/polymer compositions and use thereof

Bitumen/polymer compositions are produced by contacting, between 100.degree. C. and 230.degree. C., under agitation, one bitumen or a mixture of bitumens with at least one olefinic polymer bearing epoxy or COOH groupings, then by incorporating in the product, an acid additive while the whole mixture is agitated at a range between 100.degree. C. and 230.degree. C. for at least 10 minutes. The product, which is subjected to treatment by the acid additive may still contain one or several additional polymers, for instance of the elastomer type cross-linkable with sulphur, and even be subjected to sulphur cross-linking before treatment. The bitumen/polymer compositions are useful directly or after dilution, to form binders for carrying out surfacing operations.

BACKGROUND OF THE INVENTION 
1) Field of the Invention 
The invention relates to a process for the preparation of bitumen/polymer 
compositions with a very low temperature susceptibility. It further 
relates to the application of the compositions obtained to the production 
of bitumen/polymer binders for the preparation of coatings and in 
particular of road surfacings, of bituminous mixes or alternatively of 
watertight facings. 
2) Background Art 
It is known to use bituminous compositions as various surface coatings and 
in particular as road surface coatings, provided that these compositions 
possess a certain number of essential mechanical qualities. 
These mechanical qualities are assessed, in practice, by determining, by 
standardized tests, a series of mechanical characteristics, the most 
widely used of which are as follows: 
softening point, expressed in .degree. C. and determined by the 
ring-and-ball test defined by NF Standard T 66008, 
brittleness point or Fraass point, expressed in .degree. C. and determined 
according to IP Standard 80/53, 
penetrability, expressed in 1/10of an mm and determined according to NF 
Standard T 66004, 
tensile rheological characteristics determined according to NF Standard T 
46002 and comprising the quantities: 
yield stress .sigma..sub.y in bars, 
elongation at yield stress .epsilon..sub.y in %, 
breaking stress .sigma..sub.b in bars, 
elongation at break .epsilon..sub.y in %. 
It is also possible to obtain an indication of the temperature 
susceptibility of bituminous compositions from a correlation between the 
penetrability (abbreviated to pen) and the softening point (abbreviated to 
RBT) of the said compositions known under the name of Pfeiffer number 
(abbreviated to PN). 
This number is calculated from the relationship: 
##EQU1## 
in which A is the slope of the straight line represented by the equation: 
##EQU2## 
The temperature susceptibility of the bituminous composition decreases as 
the value of the Pfeiffer number increases or, which comes to the same 
thing, as the value of the quantity A decreases. For conventional 
bitumens, the Pfeiffer number takes values lying in the vicinity of zero. 
In general, conventional bitumens do not simultaneously exhibit all the 
required qualities and it has been known for a long time that the addition 
of varied polymers to these conventional bitumens makes it possible to 
favourably modify the mechanical properties of the latter and to form 
bitumen/polymer compositions having improved mechanical qualities with 
respect to those of the bitumens alone. 
The incorporation of olefinic polymers functionalized by epoxy or carboxyl 
groups in bituminous compositions composed of one or more bitumens or 
composed of one or more bitumens and of one or more polymers not 
containing such groups results in the production of bitumen/polymer 
compositions with significantly improved consistency (increase in the 
ring-and-ball softening point), temperature susceptibility (increase in 
the Pfeiffer number) and tensile mechanical properties. 
Such bitumen/polymer compositions, which contain olefinic polymers 
functionalized by epoxy or carboxyl groups, are described in particular in 
the references U.S. Pat. Nos. 4,650,820, 5,306,750 and 5,331,028, as well 
as in the French patent application filed by the Applicant Company on Oct. 
11, 1994 under the number 9413537. Thus, the reference U.S. Pat. No. 
4,650,820 relates to a bitumen/polymer composition containing, by weight, 
95% to 99% of a bitumen having a pseudoviscosity at 30.degree. C. lying in 
the range 200 to 1000 seconds and 1% to 5% of a terpolymer composed of 88% 
to 98.7%, on a molar basis, of units deriving from ethylene, of 1% to 10%, 
on a molar basis, of units deriving from at least one C.sub.1 to C.sub.6 
alkyl acrylate or methacrylate and of 0.3% to 3% of units deriving from 
maleic anhydride. 
The reference U.S. Pat. No. 5,306,750 describes a bitumen/polymer 
composition consisting of a reaction product obtained by bringing a 
bitumen into contact, at temperatures of 125.degree. C. to 250.degree. C. 
and with stirring for a period of time of the order of 3 hours to 48 
hours, with an ethylene copolymer containing, by weight, 0.1% to 20% of 
glycidyl groups, the amount of the copolymer representing 0.05% to 20% of 
the weight of the composition. In particular, the ethylene copolymer 
containing glycidyl groups is a random copolymer of ethylene, of 0.5 to 
15% by weight of a monomer containing a glycidyl group, in particular 
glycidyl acrylate or methacrylate, and of 0 to 50% by weight of a vinyl 
monomer without glycidyl group, such as a vinyl ester, such as vinyl 
acetate, or an alkyl acrylate or methacrylate. The reference U.S. Pat. No. 
5,331,028 relates to a bitumen/polymer composition of a type comparable to 
that described in the reference U.S. Pat. No. 5,306,750 but additionally 
containing 0.3% to 20% by weight of a block copolymer of styrene and of a 
conjugated diene, for example block copolymer of styrene and of butadiene, 
having a weight-average molecular mass ranging from 100,000 to 1,000,000. 
The subject of French Patent Application No. 9413537 is a bitumen/polymer 
composition obtained by bringing a bitumen or mixture of bitumens, a 
sulphur-crosslinkable elastomer, such as, in particular, a block copolymer 
of styrene and of a conjugated diene, an olefinic polymer containing epoxy 
or carboxyl (COOH) functional groups and a sulphur-donor coupling agent 
into contact between 100.degree. C. and 230.degree. C., with stirring. 
SUMMARY OF THE INVENTION 
It has now been found that the beneficial effect of olefinic polymers 
containing epoxy or COOH functional groups on the improvement in the 
mechanical and rheological characteristics, in particular consistency, 
temperature susceptibility and tensile mechanical properties, of 
bitumen/polymer compositions containing these functional polymers can 
still be substantially improved by treating the said compositions, after 
they have been obtained, with a specific adjuvant of the acid or acid 
anhydride type. 
The subject of the invention is thus a process for the preparation of 
bitumen/polymer compositions exhibiting, inter alia, a very low 
temperature susceptibility, in which a bitumen or mixture of bitumens is 
brought into contact, the operation being carried out at temperatures 
between 100.degree. C. and 230.degree. C. and with stirring for a time of 
at least 10 minutes, with, with respect to the weight of the bitumen or 
mixture of bitumens, 0.01% to 20%, preferably 0.05% to 10% and more 
especially 0.1% to 6% of at least one olefinic polymer carrying epoxy or 
COOH functional groups, in order to form a so-called bitumen/polymer 
component reaction product, the said process being characterized in that 
the bitumen/polymer component, maintained at temperatures of between 
100.degree. C. and 230.degree. C. and with stirring, has incorporated in 
it 0.005% to 6% and preferably 0.01% to 3%, by weight of the bitumen or 
mixture of bitumens, of an acidic adjuvant and the reaction mixture thus 
formed is maintained at temperatures of between 100.degree. C. and 
230.degree. C. and with stirring for a time of at least 10 minutes in 
order to produce the bitumen/polymer composition, the said acidic adjuvant 
being composed of one or more compounds chosen from the group formed by 
phosphoric acids, boric acids, sulphuric acid, the anhydrides of the said 
acids, chlorosulphuric acid, polyphosphoric acids, phosphonic acids of 
formula 
##STR1## 
and acids of formula R--(COO).sub.t,--SO.sub.3 H with, in the said 
formulae, t taking the value of zero or one and R denoting a monovalent 
hydrocarbon radical chosen from the group composed of C.sub.1 to C.sub.16 
acyclic monovalent hydrocarbon radicals and cyclic monovalent hydrocarbon 
radicals containing 4 to 12 cyclic carbon atoms and optionally substituted 
by C.sub.1 to C.sub.16 acyclic monovalent hydrocarbon radicals. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In particular, the acidic adjuvant can be taken from the compounds H.sub.3 
PO.sub.4, P.sub.2 O.sub.5, H.sub.3 BO.sub.3, B.sub.2 O.sub.3, H.sub.2 
SO.sub.4, SO.sub.3 and HSO.sub.3 Cl or alternatively from polyphosphoric 
acids, mixtures of at least one polyphosphoric acid and of sulphuric acid, 
mixtures of at least one polyphosphoric acid and of at least one of the 
said acids R--(COO).sub.t --SO.sub.3 H, mixtures of sulphuric acid and of 
at least one of the acids R--(COO).sub.t --SO.sub.3 H, and mixtures of 
sulphuric acid with at least one polyphosphoric acid and at least one of 
the acids R--(COO).sub.t --SO.sub.3 H. When the acidic adjuvant is based 
on one or more polyphosphoric acids, it can contain, by weight, 5% to 100% 
and more particularly 20% to 100% of one or more polyphosphoric acids and 
95% to 0% and more particularly 80% to 0% of at least one compound chosen 
from the group formed of sulphuric acid and acids R--(COO).sub.t 
--SO.sub.3 H. This type of acidic adjuvant is very especially composed of 
a combination comprising, by weight, from 20% to 95% and more particularly 
from 40% to 90% of one or more polyphosphoric acids and from 80% to 5% and 
more particularly from 60% to 10% of sulphuric acid and/or of 
methanesulphonic acid. 
When the acidic adjuvant is composed of a plurality of acidic compounds, 
the said compounds can be incorporated in the bitumen/polymer component 
either as a mixture or separately. 
The polyphosphoric acids which can be used in the process according to the 
invention are compounds of empirical formula P.sub.q H.sub.r O.sub.s in 
which q, r and s are positive numbers such that q.gtoreq.2 and in 
particular ranging from 3 to 20 or more and such that 5q+r-2s=0. 
In particular, the said polyphosphoric acids can be linear compounds of 
empirical formula P.sub.q H.sub.q+2 O.sub.3q+1 corresponding to the 
expanded formula 
##STR2## 
where q has the meaning given above, or can alternatively be products with 
a two-dimensional structure, indeed even three-dimensional structure. All 
these polyphosphoric acids can be regarded as polycondensation products 
from heating aqueous metaphosphoric acid. 
The acids of formula R--(COO).sub.t --SO.sub.3 H are either sulphonic acids 
of formula R--SO.sub.3 H, when t=0, or else acids of formula 
R--COO--SO.sub.3 H, when t=1. The acids of formula R--COO--SO.sub.3 H can 
be regarded as adducts of monocarboxylic acids R--COOH and of SO.sub.3 or 
alternatively as mixed anhydrides of monocarboxylic acids of formula 
R--COOH and of sulphuric acid. 
The monovalent hydrocarbon radical R which appears in the formula of the 
phosphonic acids 
##STR3## 
and in the formula of the acids R--(COO).sub.t --SO.sub.3 H is chosen, as 
indicated above, from C.sub.1 to C.sub.16 acyclic monovalent hydrocarbon 
radicals and cyclic monovalent hydrocarbon radicals which contain 4 to 12 
cyclic carbon atoms and which are optionally substituted by C.sub.1 to 
C.sub.16 acyclic monovalent hydrocarbon radicals. Thus, the radical R of 
acyclic type can comprise, in particular, a linear or branched C.sub.1 to 
C.sub.16 alkyl radical, for example, such as methyl, ethyl, propyl, butyl, 
hexyl, heptyl, octyl, decyl, dodecyl or alternatively tetradecyl. The 
radical R of cyclic type can comprise, in particular, a C.sub.4 to 
C.sub.12 cycloalkyl radical and more particularly a C.sub.5 to C.sub.8. 
cycloalkyl radical, such as cyclopentyl, cyclohexyl, cycloheptyl or 
cyclooctyl, or else a monovalent aromatic radical which contains 6 cyclic 
carbon atoms and which can optionally be substituted by a linear or 
branched C.sub.1 to C.sub.16 alkyl radical, such as, for example, a 
phenyl, tolyl, decylphenyl, dodecylphenyl or tetradecylphenyl radical. 
Examples of sulphonic acids of formula R--SO.sub.3 H which can be used in 
the process according to the invention are methanesulphonic acid, 
ethanesulphonic acid, propanesulphonic acid, benzenesulphonic acid, 
toluenesulphonic acid, decylbenzenesulphonic acid, dodecylbenzenesulphonic 
acid and tetradecylbenzenesulphonic acid. 
Examples of phosphonic acids of formula 
##STR4## 
which can be used in the process according to the invention are 
methylphosphonic acid, ethylphosphonic acid, propylphosphonic acid, 
butylphosphonic acid and phenylphosphonic acid. 
Mention may be made, as acids of formula R--COO--SO.sub.3 H, of the acids 
CH.sub.3 --COO--SO.sub.3 H and CH.sub.3 --CH.sub.2 --COO--SO.sub.3 H, 
which are adducts of SO.sub.3 with acetic acid and propionic acid 
respectively. 
The olefinic polymers carrying epoxy or COOH functional groups, at least 
one of which is incorporated in the bitumen or mixture of bitumens in 
order to form the bitumen/polymer component, advantageously comprise 
olefinic copolymers containing, by weight, x % of units resulting from 
ethylene or from propylene, y % of units resulting from one or more 
monomers A of formula 
##STR5## 
z % of units resulting from at least one monomer B of formula 
##STR6## 
and v % of units resulting from one or more monomers C other than the 
monomers A and B, with, in these formulae, R.sub.1 denoting H, CH.sub.3 or 
C.sub.2 H.sub.5, R.sub.2 representing a --COOR.sub.5, --OR.sub.5 or 
--OOCR.sub.6 radical with R.sub.5 denoting a C.sub.1 to C.sub.10 alkyl 
radical and preferably a C.sub.1 to C.sub.6 alkyl radical and R.sub.6 
representing H or a C.sub.1 to C.sub.3 alkyl radical, R.sub.3 denoting H, 
COOH or COOR.sub.5, R.sub.5 having the abovementioned definition, and 
R.sub.4 denoting a --COOH, 
##STR7## 
radical and x, y, z and v being numbers such that 40&lt;x&lt;99.9, 0&lt;y&lt;50, 
0.1&lt;z&lt;20 and 0&lt;v&lt;15 with x+y+z+v=100. 
Preferably, in the abovementioned copolymers, x, y, z and v are such that 
50&lt;x&lt;99.5, 0&lt;y&lt;40, 0.5&lt;z&lt;15 and 0&lt;v&lt;10 with x+y+z+v=100. 
The monomers A of formula 
##STR8## 
which supply 
##STR9## 
units in the olefinic copolymer, are chosen in particular from vinyl 
formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl ethers 
CH.sub.2 .dbd.CH--O--R.sub.5, where R.sub.5 is a C.sub.1 to C.sub.10 and 
preferably C.sub.1 to C.sub.6 alkyl radical, such as methyl, ethyl, propyl 
or butyl, or alkyl acrylates and methacrylates of formula CH.sub.2 
.dbd.CH--COOR.sub.5 and 
##STR10## 
respectively, where R.sub.5 has the meaning given above. 
The monomers B of formula 
##STR11## 
which provide 
##STR12## 
units in the olefinic copolymer, are chosen in particular from maleic acid 
and its anhydride, acrylic acid, methacrylic acid, alkyl hydrogen maleates 
of formula HOOC--CH.dbd.CH--COOR.sub.7, where R.sub.7 is a C.sub.1 to 
C.sub.6 alkyl radical, such as methyl, ethyl, propyl or butyl, glycidyl 
acrylates and methacrylates of formula 
##STR13## 
and 
##STR14## 
respectively, vinyl alcohol and glycidyl vinyl ether of formula 
##STR15## 
The monomers C, the presence of which in the olefinic copolymer is 
optional, are monomers which can be polymerized by the radical route other 
than the monomers A and B, such as, for example, CO, SO.sub.2 and 
acrylonitrile. 
In particular, the olefinic copolymers carrying epoxy or COOH functional 
groups are chosen from: 
(a) random copolymers of ethylene and of a monomer B chosen from acrylic 
acid, methacrylic acid, maleic acid or its anhydride, glycidyl acrylate 
and glycidyl methacrylate which contain, by weight, 80% to 99.7% and 
preferably 85% to 99.5% of ethylene; 
(b) random terpolymers of ethylene, of a monomer A chosen from vinyl 
acetate and alkyl acrylates or methacrylates containing a C.sub.1 to 
C.sub.6 alkyl residue, such as methyl, ethyl, propyl, butyl or hexyl, and 
of a monomer B chosen from acrylic acid, methacrylic acid, maleic acid or 
its anhydride, glycidyl acrylate and glycidyl methacrylate which contain, 
by weight, 0.5% to 40% of units resulting from the monomer A and 0.5% to 
15% of units resulting from the monomer B, the remainder being formed of 
units resulting from ethylene; and 
(c) copolymers resulting from the grafting of a monomer B, chosen from 
acrylic acid, methacrylic acid, maleic acid or its anhydride, glycidyl 
acrylate and glycidyl methacrylate, on a substrate composed of a polymer 
chosen from polyethylenes, in particular low density polyethylenes, 
polypropylenes and random copolymers of ethylene and of vinyl acetate or 
of ethylene and of alkyl acrylate or methacrylate containing a C.sub.1 to 
C.sub.6 alkyl residue, such as methyl, ethyl, propyl, butyl or hexyl, 
which contain, by weight, 40% to 99.7% and preferably 50% to 99% of 
ethylene, the said grafted copolymers containing, by weight, 0.5% to 15% 
of grafted units resulting from the monomer B. 
The olefinic copolymers chosen from: 
(i) random terpolymers of ethylene, of alkyl acrylate or methacrylate 
containing a C.sub.1 to C.sub.6 alkyl residue, such as methyl, ethyl or 
butyl, and of maleic anhydride which contain, by weight, 0.5% to 40% of 
units resulting from alkyl acrylate or methacrylate and 0.5% to 15% of 
units resulting from maleic anhydride, the remainder being formed of units 
resulting from ethylene; 
(ii) random terpolymers of ethylene, of alkyl acrylate or methacrylate 
containing a C.sub.1 to C.sub.6 alkyl residue, such as methyl, ethyl or 
butyl, and of glycidyl acrylate or methacrylate which contain, by weight, 
0.5% to 40% of units resulting from alkyl acrylate or methacrylate and 
0.5% to 15% of units resulting from glycidyl acrylate or methacrylate, the 
remainder being formed of units resulting from ethylene; 
(iii) low density polyethylenes grafted with maleic anhydride and 
polypropylenes grafted with maleic anhydride which contain, by weight, 
0.5% to 15% of grafted units resulting from maleic anhydride; 
(iv) low density polyethylenes grafted with glycidyl acrylate or 
methacrylate and polypropylenes grafted with glycidyl acrylate or 
methacrylate which contain, by weight, 0.5% to 15% of grafted units 
resulting from the glycidyl derivative, are particularly preferred. 
The olefinic copolymers carrying epoxy or COOH functional groups used to 
produce the bitumen/polymer component advantageously have molecular masses 
such that the melt flow index of the said copolymers, determined according 
to ASTM Standard D 1238 (test carried out at 190.degree. C. under a load 
of 2.16 kg), has a value, expressed in grams per 10 minutes, of between 
0.3 and 3000 and preferably between 0.5 and 900. 
The bitumen or mixture of bitumens which is employed for the implementation 
of the process according to the invention is advantageously chosen from 
the various bitumens which have a kinematic viscosity at 100.degree. C. of 
between 0.5.times.10.sup.-4 m.sup.2 /s and 3.times.10.sup.-2 m.sup.2 /s 
and preferably between 1.times.10.sup.-4 m.sup.2 /s and 2.times.10.sup.-2 
m.sup.2 /s. These bitumens may be direct distillation or vacuum 
distillation bitumens or else blown or semiblown bitumens, propane or 
pentane deasphalting residues, viscosity breaking residues, indeed even 
some petroleum cuts or mixtures of bitumens and of vacuum distillates or 
alternatively mixtures of at least two of the products which have just 
been listed. Besides a kinematic viscosity included within the 
abovementioned ranges, the bitumen or mixture of bitumens employed in the 
process according to the invention advantageously has a penetrability at 
25.degree. C., defined according to NF Standard T 66004, of between 5 and 
800 and preferably between 10 and 400. 
In addition to the olefinic polymer functionalized by epoxy or COOH groups, 
the bitumen/polymer component, which is treated with the acidic adjuvant, 
can also contain one or more additional polymers other than the said 
functionalized olefinic polymer, the said additional polymer(s) being in 
particular elastomers and especially sulphur-crosslinkable elastomers. 
These elastomers are advantageously chosen from random or block copolymers 
of styrene and of a conjugated diene, such as butadiene, isoprene, 
chloroprene, carboxylated butadiene or carboxylated isoprene, and more 
particularly are composed of one or more copolymers chosen from block 
copolymers, with or without a random hinge, of styrene and of butadiene, 
of styrene and of isoprene, of styrene and of chloroprene, of styrene and 
of carboxylated butadiene or alternatively of styrene and of carboxylated 
isoprene. The copolymer of styrene and of conjugated diene, and in 
particular each of the abovementioned copolymers, advantageously has a 
styrene content by weight ranging from 5% to 50%. The weight-average 
molecular mass of the copolymer of styrene and of conjugated diene, and in 
particular that of the abovementioned copolymers, can be, for example, 
between 10,000 and 600,000 daltons and preferably lies between 30,000 and 
400,000 daltons. The copolymer of styrene and of conjugated diene is 
preferably chosen from di- or triblock copolymers of styrene and of 
butadiene, of styrene and of isoprene, of styrene and of carboxylated 
butadiene or alternatively of styrene and of carboxylated isoprene which 
have styrene contents and weight-average molecular masses which lie within 
the ranges defined above. 
The amount of the additional polymer or polymers and in particular the 
amount of the sulphur-crosslinkable elastomer or elastomers in the 
bitumen/polymer component can be between 0.3% and 20% and preferably 
between 0.5% and 10% of the weight of the bitumen in the said component. 
The bitumen/polymer component, which contains a sulphur-crosslinkable 
elastomer in addition to the olefinic polymer functionalized by epoxy or 
COOH groups, can advantageously be subjected to crosslinking under the 
action of a sulphur-donor coupling agent in order to form a crosslinked 
bitumen/polymer component which constitutes the bitumen/polymer component 
subjected to treatment by the acidic adjuvant. 
The sulphur-donor coupling agent which is employed in the preparation of 
the crosslinked bitumen/ polymer component can be composed of a product 
chosen from the group formed by elemental sulphur, hydrocarbyl 
polysulphides, sulphur-donor vulcanization accelerators or mixtures of 
such products with one another and/or with vulcanization accelerators 
which are not sulphur donors. In particular, the sulphur-donor coupling 
agent is chosen from the products M, which contain, by weight, from 0% to 
100% of a component CA composed of one or more sulphurdonor vulcanization 
accelerators and from 100% to 0% of a component CB composed of one or more 
vulcanizing agents chosen from elemental sulphur and hydrocarbyl 
polysulphides, and the products N, which contain a component CC composed 
of one or more vulcanization accelerators which are not sulphur donors and 
a product M in a ratio by weight of the component CC to the product M 
ranging from 0.01 to 1 and preferably from 0.05 to 0.5. 
The elemental sulphur capable of being employed for constituting, partially 
or entirely, the coupling agent is advantageously sulphur in flower form 
and preferably sulphur crystallized in the orthorhombic form and known by 
the name of alpha sulphur. 
The hydrocarbyl polysulphides capable of being employed to form part or all 
of the coupling agent may be chosen from those which are defined in the 
citation FR-A-2,528,439 and which correspond to the general formula 
R.sub.8 --(S).sub.m --(R.sub.9 --(S).sub.m).sub.w --R.sub.10 in which 
R.sub.8 and R.sub.10 each denote a saturated or unsaturated, C.sub.1 to 
C.sub.20 monovalent hydrocarbon radical or are connected to one another to 
constitute a saturated or unsaturated, C.sub.1 to C.sub.20 divalent 
hydrocarbon radical forming a ring with the other groups of atoms 
associated in the formula, R.sub.9 is a saturated or unsaturated, C.sub.1 
to C.sub.20 divalent hydrocarbon radical, the--(S).sub.m --groups 
represent divalent groups each formed from m sulphur atoms, the values m 
being able to differ from one of the said groups to another and denoting 
integers ranging from 1 to 6 with at least one of the values of m equal to 
or greater than 2 and w represents an integer assuming values from zero to 
10. Preferred polysulphides correspond to the formula R.sub.11 --(S).sub.p 
--R.sub.11, in which R.sub.11, denotes a C.sub.6 to C.sub.16 alkyl 
radical, for example hexyl, octyl, dodecyl, tert-dodecyl, hexadecyl, nonyl 
or decyl, and--(S).sub.p --represents a divalent group formed from a chain 
sequence of p sulphur atoms, p being an integer ranging from 2 to 5. 
When the coupling agent contains a sulphur-donor vulcanization accelerator, 
the latter may be chosen in particular from the thiuram polysulphides of 
formula 
##STR16## 
in which the symbols R.sub.12, which are identical or different, each 
represent a C.sub.1 to C.sub.12 and preferably C.sub.1 to C.sub.8 
hydrocarbon radical, especially an alkyl, cycloalkyl or aryl radical, or 
else two R.sub.12 radicals attached to the same nitrogen atom are bonded 
together to form a C.sub.2 to C.sub.8 divalent hydrocarbon radical and u 
is a number ranging from 2 to 8. As examples of such vulcanization 
accelerators, there may be mentioned especially the compounds: 
dipentamethylenethiuram disulphide, dipentamethylenethiuram tetrasulphide, 
dipentamethylenethiuram hexasulphide, tetrabutylthiuram disulphide, 
tetraethylthiuram disulphide and tetramethylthiuram disulphide. 
As other examples of sulphur-donor vulcanization accelerators, there may 
also be mentioned alkylphenol disulphides and disulphides such as 
morpholine disulphide and N,N'-caprolactam disulphide. 
Vulcanization accelerators which are not sulphur donors and which can be 
employed for forming the component CC of the coupling agents of product N 
type may be sulphur compounds chosen especially from mercaptobenzothiazole 
and its derivatives, especially benzothiazole metal thiolates and above 
all benzothiazolesulphenamides, dithiocarbamates of formula 
##STR17## 
Y, in which the symbols R.sub.12, which are identical or different, have 
the meaning given above, Y represents a metal and f denotes the valency of 
Y, and thiuram monosulphides of formula 
##STR18## 
in which the symbols R.sub.12 have the meaning given above. 
Examples of vulcanization accelerators of the mercaptobenzothiazole type 
can be mercaptobenzothiazole, benzothiazolethiolate of a metal such as 
zinc, sodium or copper, benzothiazyl disulphide, 
2-benzothiazolepentamethylenesulphenamide, 
2-benzothiazolethiosulphenamide, 2-benzothiazoledihydrocarbylsulphenamides 
in the case of which the hydrocarbyl radical is an ethyl, isopropyl, 
tert-butyl or cyclohexyl radical, and 
N-oxydiethylene-2-benzothiazolesulphenamide. 
Among the vulcanization accelerators of the dithiocarbamate type of the 
abovementioned formula, there may be mentioned the compounds which are 
dimethyldithiocarbamates of metals such as copper, zinc, lead, bismuth and 
selenium, diethyldithiocarbamates of metals such as cadmium and zinc, 
diamyldithiocarbamates of metals such as cadmium, zinc and lead, and lead 
or zinc pentamethylenedithiocarbamate. 
By way of examples of thiuram monosulphides which have the formula given 
above, there may be mentioned compounds such as dipentamethylenethiuram 
monosulphide, tetramethylthiuram monosulphide, tetraethylthiuram 
monosulphide and tetrabutylthiuram monosulphide. 
Other vulcanization accelerators which are not sulphur donors and which do 
not belong to the classes defined above may also be employed. Such 
vulcanization accelerators can be 1,3-diphenylguanidine, 
di-orthotolylguanidine and zinc oxide, the latter compound being used 
optionally in the presence of fatty acid. 
For further details on the sulphur-donor vulcanization accelerators and 
those which are not sulphur donors which can be used in the formation of 
the coupling agent, reference may be made to citations EP-A-0,360,656 and 
EP-A-0,409,683, the contents of which are incorporated in the present 
description by reference, as are the contents of citation FR-A-2,528,439. 
As follows from its composition, as indicated above, the coupling agent may 
be of the single-component or of the multicomponent type, it being 
possible for the coupling agent of the multicomponent type to be formed 
before it is used or alternatively produced in situ in the mixture in 
which it must be present. The coupling agent of the preformed 
multicomponent type or of the single-component type or the components of 
the coupling agent of the multicomponent type formed in situ may be used 
as they are, for example in the molten state, or else as a mixture, for 
example in solution or in suspension, with a diluent, for example a 
hydrocarbon compound. 
The coupling agent is used in an amount appropriate for providing an amount 
of free sulphur representing 0.1% to 20% and preferably 0.5% to 10% of the 
weight of sulphur-crosslinkable elastomer in the bitumen/polymer component 
which is subjected to crosslinking by the coupling agent. 
The bitumen/polymer component, which is subjected to the action of the 
acidic adjuvant, is prepared by bringing the olefinic polymer carrying 
epoxy or carboxyl functional groups and, if appropriate, the additional 
polymer or polymers, for example sulphur-crosslinkable elastomer, into 
contact with the bitumen or mixture of bitumens, in proportions chosen 
within the ranges defined above, the operation being carried out at 
temperatures of between 100.degree. C. and 230.degree. C., more 
particularly between 120.degree. C. and 190.degree. C., and with stirring, 
for a period of time of at least 10 minutes, generally of the order of a 
few tens of minutes to a few hours and for example from 10 minutes to 8 
hours and more particularly from 10 minutes to 5 hours, to form a reaction 
product constituting the bitumen/polymer component. When an additional 
polymer, for example a sulphur-crosslinkable elastomer, is used in 
addition to the olefinic polymer functionalized by epoxy or COOH groups, 
the said additional polymer can be brought into contact with the bitumen 
or mixture of bitumens before or after the functionalized olefinic polymer 
or even at the same time as the latter. 
When it is desired to produce a crosslinked bitumen/polymer component, a 
non-crosslinked bitumen/polymer component composed of a bitumen or mixture 
of bitumens containing at least one olefinic polymer carrying epoxy or 
COOH functional groups and at least one sulphur-crosslinkable elastomer, 
for example a block copolymer of styrene and of a conjugated diene, is 
first of all formed, the operation being carried out as indicated above, 
the sulphur-donor coupling agent is then incorporated in the said 
non-crosslinked bitumen/polymer component, in an appropriate amount chosen 
within the ranges defined above for the said amount, and the whole mixture 
is kept stirring at temperatures of between 100.degree. C. and 230.degree. 
C., more particularly between 120.degree. C. and 190.degree. C., and 
identical or not to the temperatures for the preparation of the 
non-crosslinked bitumen/polymer component, for a period of time of at 
least 10 minutes and generally ranging from 10 minutes to 5 hours, more 
particularly from 30 minutes to 3 hours, to form a reaction mass 
constituting the sulphur-crosslinked bitumen/polymer component. 
The non-crosslinked or crosslinked bitumen/polymer component is treated 
with the acidic adjuvant by incorporating the said acidic adjuvant, in an 
appropriate amount chosen within the ranges defined above for the said 
amount, in the said bitumen/polymer component, maintained at temperatures 
of between 100.degree. C. and 230.degree. C., more particularly between 
120.degree. C. and 190.degree. C., and with stirring, and by then 
maintaining the whole mixture at temperatures of between 100.degree. C. 
and 230.degree. C., more particularly between 120.degree. C. and 
190.degree. C., and with stirring, for a period of time of at least 10 
minutes and in particular from 10 minutes to 5 hours, more particularly 
from 30 minutes to 4 hours, to produce the bitumen/polymer composition 
with a very low temperature susceptibility. 
During its formation, the bitumen/polymer component of the non-crosslinked 
type or of the sulphur-crosslinked type, which is subsequently subjected 
to the action of the acidic adjuvant, may further have added to it 1% to 
40% and more particularly 2% to 30%, by weight of the bitumen, of a 
fluxing agent which may be composed, in particular, of a hydrocarbon oil 
exhibiting an atmospheric pressure distillation range, determined 
according to ASTM Standard D 86-67, of between 100.degree. C. and 
600.degree. C. and lying more especially between 150.degree. C. and 
400.degree. C. This hydrocarbon oil, which can especially be a petroleum 
cut of aromatic nature, a petroleum cut of naphtheno-aromatic nature, a 
petroleum cut of naphtheno-paraffinic nature, a petroleum cut of 
paraffinic nature, a coal oil or alternatively an oil of plant origin, is 
sufficiently "heavy" to limit the evaporation at the time of its addition 
to the bitumen and, at the same time, sufficiently "light" to be removed 
as much as possible after the bitumen/polymer composition containing it 
has been spread, so as to regain the same mechanical properties which the 
bitumen/polymer composition prepared without employing any fluxing agent 
would have exhibited after hot spreading. The fluxing agent can be added 
to the reaction mixture, which is formed from the bitumen, from the 
sulphur-crosslinkable elastomer and from the sulphurdonor coupling agent, 
at any time in the formation of the said reaction mixture, the amount of 
fluxing agent being chosen, within the range defined above, in order to be 
compatible with the desired final use on the work site. 
The reaction mixture based on bitumen or mixture of bitumens, on olefinic 
polymer carrying epoxy or COOH functional groups and, when they are used, 
on additional polymer, such as, for example, sulphur-crosslinkable 
elastomer and sulphur-donor coupling agent, which gives rise to the 
non-crosslinked or crosslinked bitumen/polymer component which is 
subsequently treated with the acidic adjuvant, can also contain one or 
more additives capable of reacting with the epoxy or COOH groups of the 
functionalized olefinic polymer. These reactive additives can be, in 
particular, primary or secondary amines, especially polyamines, alcohols, 
especially polyols, acids, especially polyacids, or alternatively metal 
salts. 
Reactive additives of the amine type are, for example, aromatic diamines, 
such as 1,4-diaminobenzene, 2,4-diaminotoluene, diaminonaphthalene, 
bis(4-aminophenyl) sulphone, bis(4-aminophenyl) ether or 
bis(4-aminophenyl)methane, aliphatic or cycloaliphatic diamines, such as 
those of formula H.sub.2 N--R.sub.13 --NH.sub.2, where R.sub.13 denotes a 
C.sub.2 to C.sub.12 alkylene or C.sub.6 to C.sub.12 cycloalkylene radical, 
for example ethylenediamine, diaminopropane, diaminobutane, diaminohexane, 
diaminooctane, diaminodecane, diaminododecane, diaminocyclohexane, 
diaminocyclooctane or diaminocyclododecane, polyethylenepolyamines or 
polypropylenepolyamines, such as diethylenetriamine, triethylenetetramine, 
tetraethylenepentamine or dipropylenetriamine, or alternatively fatty 
amines or polyamines, that is to say amines or polyamines containing a 
C.sub.12 to C.sub.18 alkyl or alkenyl radical connected to the nitrogen 
atom of an amine group. 
Reactive additives of the alcohol type are, in particular, polyols, such as 
diols or triols and especially diols of formula HO--R.sub.14 --OH, where 
R.sub.14 denotes a hydrocarbon radical, especially a C.sub.2 to C.sub.18 
alkylene, C.sub.6 to C.sub.8 arylene and C.sub.6 to C.sub.8 cycloalkylene 
radical, and polyetherdiols of formula HO--[C.sub.q H.sub.2q O].sub.r --H, 
where q is a number ranging from 2 to 6 and especially equal to 2 or 3 and 
r is a number at least equal to 2 and, for example, ranging from 2 to 20. 
Examples of such polyols are ethylene glycol, propylene glycol, butylene 
glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 
hexanediol, octanediol or polyhydroxylated polybutadiene. 
Reactive additives of the acid type are, in particular, polyacids of 
formula HOOC--R.sub.14 --COOH, where R.sub.14 has the meaning given above. 
Examples of such polyacids are phthalic acid, terephthalic acid, malonic 
acid, succinic acid, adipic acid, glutaric acid or polycarboxylated 
polybutadiene. 
Reactive additives of the metal salt type are, in particular, compounds, 
such as hydroxides, oxides, alkoxides, carboxylates, such as formates and 
acetates, methoxides, ethoxides, nitrites, carbonates and bicarbonates, of 
metals from groups I, II, III and VIII of the Periodic Table of the 
Elements, especially Na, K, Li, Mg, Ca, Cd, Zn, Ba, Al or Fe. 
The amount of the reactive additive or of the reactive additives, which are 
incorporated in the reaction mixture giving rise to the bitumen/polymer 
components, can range from 0.01% to 10% and more particularly from 0.05% 
to 5% of the weight of bitumen present in the said reaction mixture. 
In addition to the reactive additives and the fluxing agent, it is also 
possible to incorporate in the reaction mixture generating the 
bitumen/polymer components, at any point in the formation of the said 
reaction mixture, additives conventionally used in bitumen/polymer 
compositions, such as promoters of adhesion of the bitumen/polymer 
composition to mineral surfaces or alternatively fillers, such as talc, 
carbon black or worn tires reduced to fine powder. 
In an embodiment of the preparation of the bitumen/polymer component using 
a hydrocarbon oil as defined above as fluxing agent, the olefinic polymer 
carrying epoxy or COOH functional groups and, if they are present, the 
additional polymer and the sulphur-donor coupling agent are incorporated 
in the bitumen or mixture of bitumens in the form of a mother solution of 
these products in the hydrocarbon oil constituting the fluxing agent. 
The mother solution is prepared by bringing ingredients composing it, 
namely hydrocarbon oil serving as solvent, olefinic polymer containing 
epoxy or COOH groups and, if present, additional polymer, such as 
sulphur-crosslinkable elastomer, and sulphur-donor coupling agent, into 
contact, with stirring, at temperatures of between 10.degree. C. and 
170.degree. C. and more particularly between 40.degree. C. and 120.degree. 
C., for a sufficient period of time, for example between 10 minutes and 2 
hours, to obtain complete dissolution of the polymeric ingredients and of 
the coupling agent in the hydrocarbon oil. 
The respective concentrations of the olefinic polymer containing epoxy or 
COOH groups, of the additional polymer and of the coupling agent in the 
mother solution can vary fairly widely, depending, in particular, on the 
nature of the hydrocarbon oil used to dissolve the said polymer 
ingredients and coupling agent. Thus, the respective amounts of 
functionalized olefinic polymer, of additional polymer and of coupling 
agent can advantageously represent 1% to 20%, 5% to 30% and 0.005% to 6% 
of the weight of the hydrocarbon oil. 
To prepare the bitumen/polymer components by resorting to the mother 
solution technique, the mother solution containing the functionalized 
olefinic polymer and, if used, the additional polymer and the sulphurdonor 
coupling agent is mixed with the bitumen or mixture of bitumens, the 
operation being carried out at temperatures of between 100.degree. C. and 
230.degree. C., more particularly between 120.degree. C. and 190.degree. 
C., and with stirring, this being carried out, for example, by 
incorporating the mother solution in the bitumen kept stirring at 
temperatures between 100.degree. C. and 230.degree. C. and more 
particularly between 120.degree. C. and 190.degree. C., and then the 
resulting mixture is kept stirring at temperatures of between 100.degree. 
C. and 230.degree. C., more particularly between 120.degree. C. and 
190.degree. C., for example at the temperatures used to prepare the 
mixture of the mother solution with the bitumen, for a period of time at 
least equal to 10 minutes and generally ranging from 10 minutes to 2 
hours, to form a reaction product constituting the bitumen/polymer 
component. 
The amount of mother solution mixed with the bitumen or mixture of bitumens 
is chosen to yield the desired amounts, with respect to the bitumen, of 
olefinic polymer containing epoxy or COOH groups, of additional polymer 
and of sulphur-donor coupling agent, the said amounts being within the 
ranges defined above. 
The bitumen/polymer compositions with a very low temperature susceptibility 
obtained by the process according to the invention can be used as is or 
else diluted with variable proportions of a bitumen or mixture of bitumens 
or of a composition according to the invention having different 
characteristics, in order to form bitumen/polymer binders having a chosen 
content of crosslinked elastomer which can either be equal to (undiluted 
composition) or else lower than (diluted composition) the content of 
crosslinked elastomer in the corresponding initial bitumen/polymer 
compositions. The dilution of the bitumen/polymer compositions according 
to the invention with the bitumen or mixture of bitumens or with a 
composition according to the invention with different characteristics can 
be carried out either directly following the preparation of the said 
compositions, when a virtually immediate use of the resulting 
bitumen/polymer binders is required, or else alternatively after a more or 
less prolonged period of storage of the bitumen/polymer compositions, when 
a delayed use of the resulting bitumen/polymer binders is envisaged. The 
bitumen or mixture of bitumens used for the dilution of a bitumen/polymer 
composition according to the invention can be chosen from the bitumens 
defined above as being suitable f or the preparation of bitumen/polymer 
compositions. If appropriate, the bitumen or mixture of bitumens used for 
the dilution can itself have been pretreated with an acidic adjuvant 
according to the invention. 
The dilution of a bitumen/polymer composition by a bitumen or mixture of 
bitumens or by a second composition according to the invention with a 
lower content of polymer (functionalized olefinic polymer and, if present, 
additional polymer), in order to form a bitumen/polymer binder with a 
chosen content of polymer lower than that in the bitumen/polymer 
composition to be diluted, is generally carried out by bringing into 
contact, with stirring and at temperatures of between 100.degree. C. and 
230.degree. C. and more particularly between 120.degree. C. and 
190.degree. C. , suitable proportions of the bitumen/polymer composition 
to be diluted and of bitumen or mixture of bitumens or of second 
bitumen/polymer composition according to the invention. 
The bitumen/polymer binders composed of the bitumen/polymer compositions 
according to the invention or resulting from the dilution of the said 
compositions by a bitumen or mixture of bitumens or by another 
bitumen/polymer composition according to the invention, up to the desired 
content of polymer(s) in the said binders, can be applied, directly or 
after conversion into aqueous emulsion, to the production of road 
surfacings of the surface coating type, to the production of bituminous 
mixes which are put in place with heating or cold, or else to the 
production of watertight facings. 
The invention is illustrated by the following examples, given without 
implied limitation. 
In these examples, the amounts and percentages are expressed by weight, 
except when otherwise indicated. 
In addition, the rheological and mechanical characteristics of the bitumens 
or bitumen/polymer compositions to which reference is made in the said 
examples, namely penetrability, ring-and-ball softening point and Pfeiffer 
number (PN), are those defined above.

EXAMPLES 1 TO 9 
Bituminous (Example 1) or bitumen/polymer (Examples 2, 4, 6 and 8) control 
compositions were prepared, as well as bitumen/polymer compositions 
according to the invention (Examples 3, 5, 7 and 9), in order to evaluate 
and compare the physicomechanical characteristics thereof. 
The preparations were carried out under the following conditions 
Example 1 
(Control) 
Preparation of a bituminous composition composed of a bitumen modified by 
an acidic adjuvant. 
1000 parts of a bitumen having a penetrability, determined according to the 
conditions of NF Standard T 66004, within the range 70/100 and 5 parts of 
75% phosphoric acid were introduced into a reactor maintained at 
175.degree. C. and with stirring. The contents of the reactor were 
subsequently maintained at 175.degree. C. with stirring for a period of 
time equal to 3 hours, in order to produce the bituminous composition. 
Example 2 
(Control) 
Preparation of a bitumen/polymer composition untreated by an acidic 
adjuvant. 
980 parts of a bitumen identical to that used in Example 1, as well as 20 
parts of an ethylene/methyl acrylate/glycidyl methacrylate terpolymer 
containing 24% of methyl arcrylate and 8% of glycidyl methacrylate and 
possessing a melt flow index, determined according to ASTM Standard D 
1238, having a value equal to 6 g per 10 minutes, were introduced into a 
reactor maintained at 175.degree. C. and with stirring. After mixing for 
2.5 hours with stirring at 175.degree. C., a homogeneous mass constituting 
the bitumen/polymer composition was obtained. 
Example 3 
(According to the Invention) 
Preparation of a bitumen/polymer composition by treating a non-crosslinked 
bitumen/polymer component with an acidic adjuvant. 
980 parts of a bitumen identical to that used in Example 1, as well as 20 
parts of the terpolymer used in Example 2, were introduced into a reactor 
maintained at 175.degree. C. and with stirring, and the whole mixture was 
kept stirring at 175.degree. C. for 2.5 hours. 
5 parts of 75% phosphoric acid were then added to the contents of the 
reactor and the whole mixture was subsequently maintained at 175.degree. 
C. with stirring for 3 hours, in order to form the bitumen/polymer 
composition. 
Example 4 
(Control) 
Preparation of a non-crosslinked bitumen/polymer composition including an 
elastomer, which composition is not treated with an acidic adjuvant. 
955 parts of a bitumen identical to that used in Example 1 and then 30 
parts of an elastomer composed of a styrene/butadiene/styrene triblock 
copolymer, having an average molecular mass of 150,000 daltons and 
containing 30% of styrene, and 15 parts of the terpolymer used in Example 
2 were introduced into a reactor maintained at 175.degree. C. and with 
stirring. The contents of the reactor were subsequently kept stirring at 
175.degree. C. for 2.5 hours in order to form the non-crosslinked 
bitumen/polymer composition. 
Example 5 
(According to the Invention) 
Preparation of a non-crosslinked bitumen/polymer composition including an 
elastomer, which composition is treated with an acidic adjuvant. A 
non-crosslinked bitumen/polymer composition including an elastomer, the 
so-called bitumen/polymer component, was prepared using the procedure 
described in Example 4. 4 parts of a polyphosphoric acid were then 
incorporated in the contents of the reactor and then the reaction mixture 
thus formed was maintained at 175.degree. C. and with stirring for a 
period of time equal to 2.5 hours, in order to produce the bitumen/polymer 
composition according to the invention. The polyphosphoric acid used 
corresponded to the formula P.sub.n H.sub.n+2 O.sub.3n+1, n being a number 
equal to approximately 3. 
Example 6 
(Control) 
Preparation of a non-crosslinked bitumen/polymer composition which is not 
treated with an acidic adjuvant. 
A bitumen/polymer composition was prepared using the procedure described in 
Example 2, with, however, use of a bitumen having a penetrability within 
the range 180/220. 
Example 7 
(According to the Invention) 
Preparation of a bitumen/polymer composition by treating a bitumen/polymer 
component with an acidic adjuvant. 
A non-crosslinked bitumen/polymer composition, the so-called 
bitumen/polymer component, was prepared using the procedure described in 
Example 6.3 parts of methanesulphonic acid were then incorporated in the 
contents of the reactor and then the whole mixture was maintained at 
175.degree. C., with stirring, for a period of time of 3 hours, in order 
to produce the bitumen/polymer composition according to the invention. 
Example 8 
(Control) 
Preparation of a crosslinked bitumen/polymer composition which is not 
treated with an acidic adjuvant. 
960 parts of a bitumen identical to that used in Example 6 and then 30 
parts of an elastomer composed of a styrene/butadiene diblock copolymer, 
having an average molecular mass of 100,000 daltons and a styrene content 
of 25%, and 10 parts of the terpolymer used in Example 2 were introduced 
into a reactor maintained at 175.degree. C. and with stirring, and the 
reaction mixture thus formed was kept stirring at 175.degree. C. for 2.5 
hours. 0.8 part of sulphur was then added to the contents of the reactor 
and the whole mixture was kept stirring at 175.degree. C. for 3 hours, in 
order to form a crosslinked bitumen/polymer composition. 
Example 9 
(According to the Invention) 
Preparation of a crosslinked bitumen/polymer composition which is treated 
with an acidic adjuvant. 
A sulphur-crosslinked bitumen/polymer composition, the so-called 
crosslinked bitumen/polymer component, was prepared using the procedure 
described in Example 8. 5 parts of 98% sulphuric acid were then 
incorporated in the contents of the reactor and then the reaction mixture 
thus formed was maintained at 175.degree. C. and with stirring for a 
period of time of 2.5 hours, in order to produce the crosslinked 
bitumen/polymer composition treated with an acidic adjuvant according to 
the invention. 
For each of the compositions obtained as indicated in Examples 1 to 9, the 
following characteristics were determined: 
penetrability at 25.degree. C. (Pen.), 
ring-and-ball softening temperature (RBT), 
Pfeiffer number (PN). 
The results obtained are collated in the table below. 
In this table, the abbreviations BT1, BT2, TPO, SBS and SB have the 
following meanings: 
BT1: unmodified bitumen with a penetrability within the range 70/100; 
BT2: unmodified bitumen with a penetrability within the range 180/220, 
TPO: ethylene/methyl acrylate/glycidyl methacrylate terpolymer used in 
Examples 2, 3, 4, 5, 6, 7, 8 and 9; 
SBS: styrene/butadiene/styrene triblock copolymer used in Examples 4 and 5; 
SB: styrene/butadiene diblock copolymer used in Examples 8 and 9. 
The contents of TPO, SBS and SB in the compositions are expressed as 
percentages by weight of the overall amounts of bitumen and polymer(s). 
The sulphur content is expressed as % of the weight of the bitumen. 
TABLE 
__________________________________________________________________________ 
Nature of the 
TPO 
SBS 
SB Sulphur 
Pen RBT 
Examples 
acidic adjuvant 
(%) 
(%) 
(%) 
(%) (1/10 mm) 
(.degree. C.) 
PN 
__________________________________________________________________________ 
BT1 90 46 -0.8 
1 Phosphoric acid 75 53 0.6 
2 No acidic 
2 85 55 1.4 
adjuvant 
3 Phosphoric acid 
2 60 69.4 
3.2 
4 No acidic 
1.5 
3 55 65 2.2 
adjuvant 
5 Polyphosphoric 
1.5 
3 45 76 3.5 
acid 
BT2 190 40.9 
0.12 
6 No acidic 
2 139 50 1.9 
adjuvant 
7 Methanesulphonic 
2 93 58.9 
2.6 
acid 
8 No acidic 
1 3 0.1 118 60 3.7 
adjuvant 
9 H.sub.2 SO.sub.4 
1 3 0.1 75 72 4.3 
__________________________________________________________________________ 
In the light of the characteristics collated in the table, it is apparent 
that: 
the incorporation of a functionalized olefinic polymer according to the 
invention, for example olefinic polymer carrying epoxy groups, in a 
bitumen improves the physical properties of the said bitumen (increase in 
the RBT value and in the Pfeiffer number), as is evident from the 
comparison of Example 2 with BT1 or of Example 6 with BT2; 
the addition of an acidic adjuvant according to the invention to a bitumen 
also reinforces the consistency of the bitumen (increase in the RBT value 
and in the Pfeiffer number), as is evident from the comparison of Example 
1 with BT1; 
the addition of an acidic adjuvant according to the invention to a bitumen 
modified by a functionalized olefinic polymer according to the invention, 
for example olefinic polymer carrying epoxy groups, results in an 
increased reinforcement of the physical properties of the composition 
(greater increase in the RBT value and in the Pfeiffer number than in the 
preceding case) by a phenomenon of synergy between the two modification 
agents, namely functionalized olefinic polymer and acidic adjuvant, as is 
evident emerges from the comparison of the results of Example 3 with the 
results of Control Examples 1 and 2; 
the abovementioned synergy effect is magnified when the bitumen/polymer 
component treated with the acidic adjuvant contains an elastomer in 
addition to the functionalized olefinic polymer, as may be seen in the 
comparison of the results of Example 5 according to the invention with the 
results of Control Example 4; 
the magnified synergy effect is even more marked if the bitumen/polymer 
composition containing an elastomer, which is subjected to the treatment 
with the acidic adjuvant, has been subjected to crosslinking with sulphur 
prior to the said treatment, as is evident from the comparison of the 
results of Example 9 according to the invention with the results of 
Control Example 8.