U.S. patent application number 12/670375 was filed with the patent office on 2010-07-29 for graft polymer and thermoreversibly cross-linked bitumen composition comprising said graft polymer.
This patent application is currently assigned to TOTAL RAFFINAGE MARKETING. Invention is credited to Pierre Chaverot, Charlotte Godivier, Ilias Iliopoulos, Amanda Kathryn Leach, Ludwik Leibler.
Application Number | 20100190894 12/670375 |
Document ID | / |
Family ID | 39144346 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100190894 |
Kind Code |
A1 |
Chaverot; Pierre ; et
al. |
July 29, 2010 |
GRAFT POLYMER AND THERMOREVERSIBLY CROSS-LINKED BITUMEN COMPOSITION
COMPRISING SAID GRAFT POLYMER
Abstract
The disclosure relates to a bitumen/polymer composition
comprising at least one bitumen and at least one graft polymer, the
grafts enabling the bitumen/polymer compositions to be
thermoreversibly cross-linked. The disclosure also relates to the
use of said bitumen/polymer compositions in fields of application
relating to roads, especially in the production of asphalt binders,
and in industrial fields of application. The disclosure further
relates to the method for producing said thermoreversibly
cross-linked bitumen/polymer compositions.
Inventors: |
Chaverot; Pierre; (Sainte
Croix en Jarex, FR) ; Godivier; Charlotte; (Malakoff,
FR) ; Leibler; Ludwik; (Paris, FR) ;
Iliopoulos; Ilias; (Paris, FR) ; Leach; Amanda
Kathryn; (Scotia, NY) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
TOTAL RAFFINAGE MARKETING
Puteaux
FR
CENTRE NATIONAL DE RECHERCHE SCIENTIFIQUE (CNRS)
Paris
FR
|
Family ID: |
39144346 |
Appl. No.: |
12/670375 |
Filed: |
July 18, 2008 |
PCT Filed: |
July 18, 2008 |
PCT NO: |
PCT/FR08/01063 |
371 Date: |
January 22, 2010 |
Current U.S.
Class: |
524/68 ;
525/98 |
Current CPC
Class: |
C08L 51/06 20130101;
C09D 195/00 20130101; C08C 19/22 20130101; C08J 3/246 20130101;
C09D 195/00 20130101; C08L 95/00 20130101; C08L 53/02 20130101;
C08L 15/00 20130101; C08C 19/04 20130101; C08L 2666/24 20130101;
C08L 2666/24 20130101; C08J 2395/00 20130101; C08C 19/20 20130101;
C08L 95/00 20130101 |
Class at
Publication: |
524/68 ;
525/98 |
International
Class: |
C08L 95/00 20060101
C08L095/00; C08F 287/00 20060101 C08F287/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 2007 |
FR |
0705366 |
Claims
1. A graft polymer comprising a polymer main chain and at least one
side graft linked to the polymer main chain, the polymer main chain
being obtained from at least one diene unit, the graft comprising a
branched, linear or saturated hydrocarbon chain, having at least 18
carbon atoms.
2. The graft polymer according to claim 1 in which the branched,
linear or saturated hydrocarbon chain of at least 18 carbon atoms
has the general formula C.sub.nH.sub.2n+1, where n represents an
integer greater than or equal to 18.
3. The graft polymer according to claim 1 in which the polymer
results from the copolymerisation of conjugated diene units and
aromatic monovinyl hydrocarbon units.
4. The graft polymer according to claim 1 in which the polymer main
chain of the polymer comprises reactive double bonds, in particular
pendant vinyl double bonds originating from the 1-2 addition of
conjugated diene units, in particular butadiene units.
5. The graft polymer according to claim 1 in which the polymer has
a content by weight of pendant vinyl double-bond units originating
from the 1-2 addition of butadiene from 5% to 50%.
6. The graft polymer according to claim 1 in which the graft has
the general formula C.sub.nH.sub.2n+1--XH where X represents a
sulphur atom, an oxygen atom or the NH group and n represents an
integer varying from 18 to 110.
7. The graft polymer according to claim 1 in which the graft has
the general formula
C.sub.nH.sub.2n+1--(OCH.sub.2CH.sub.2).sub.m--XH where X represents
a sulphur atom, an oxygen atom or the NH group, n represents an
integer varying from 18 to 110 and m represents an integer varying
from 1 to 20.
8. The graft polymer according to claim 1 obtained by reaction
between at least one double bond of polymer, in particular a
pendant vinyl double bond originating from the 1-2 addition of a
conjugated diene unit of polymer and a reactive function of a graft
chosen from the thiol, alcohol or amine functions.
9. The graft polymer according to claim 1 comprising at least two
grafts per main polymer chain.
10. A use of at least one graft polymer according to claim 1 in
bitumen in order to obtain a bitumen/polymer composition.
11. A bitumen/polymer composition comprising at least one bitumen
and at least one polymer, in which the polymer is a graft polymer
according to claim 1.
12. A bitumen/polymer composition according to claim 11 in which
the content of the graft polymer by weight with respect to the
bitumen is from 0.1 to 30%.
13. A process for the ex situ preparation of bitumen/polymer
compositions according to claim 11 in which: a) a bitumen is
introduced into a receiving vessel equipped with a mixer means, and
the bitumen is taken to a temperature comprised between 90 and
220.degree. C., b) from 0.1 to 30%, by mass of a graft polymer with
respect to the mass of bitumen is introduced, and c) the
composition is heated at a temperature comprised between 90 and
220.degree. C., under stirring, until a homogeneous final
bitumen/polymer composition is obtained.
14. A process for the in situ preparation of bitumen/polymer
compositions according to claim 11 in which: a) a bitumen is
introduced into a receiving vessel equipped with a mixer means, and
the bitumen is taken to a temperature between 90 and 220.degree.
C., b) from 0.1 to 30%, preferably 0.1 to 10% by mass of a polymer
and from 0.1 to 30%, by mass of a graft with respect to the mass of
bitumen are introduced, and c) the composition is heated at a
temperature comprised between 90 and 220.degree. C., under
stirring, until a homogeneous final bitumen/polymer composition is
obtained.
15. A use of bitumen/polymer compositions according to claim 11 in
order to produce a bituminous binder, in particular in anhydrous
form, in the form of an emulsion or in the form of fluxed
bitumen.
16. A use of bitumen/polymer compositions according to claim 11 in
a mixture with aggregates for producing a surface dressing, a hot
mix, a cold mix, a cold-cast mix, or an emulsion gravel.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a National Phase Entry of International
Application No. PCT/FR2008/001063, filed on Jul. 18, 2008, which
claims priority to French application 07 05 366, filed on Jul. 24,
2007, both of which are incorporated by reference herein.
TECHNICAL FIELD
[0002] The present invention belongs to the field of
bitumens/polymers. More specifically, it relates to a polymer
making it possible to obtain thermoreversibly crosslinked
bitumen/polymer compositions. The invention also relates to
thermoreversibly crosslinked bitumen/polymer compositions. The
invention also relates to the use of these bitumen/polymer
compositions in the fields of highway applications, in particular
in the production of road binders, and in the fields of industrial
applications. The invention also relates to the process for the
preparation of these thermoreversibly crosslinked bitumen/polymer
compositions.
TECHNICAL BACKGROUND
[0003] The use of bitumen in the production of materials for
highway and industrial applications has been known for a long time:
bitumen is the main hydrocarbon binder used in the field of road
construction or civil engineering. To be able to be used as a
binder in these different applications, the bitumen must have
certain mechanical properties, in particular elastic or cohesive
properties. Since bitumen on its own is generally not sufficiently
elastic or cohesive, polymers are added which can optionally be
crosslinked. These polymers, crosslinked or not, provide improved
elastic and cohesive properties to the bitumen/polymer. Generally,
the crosslinking is irreversible; once the crosslinking has been
carried out, it is not possible to return to the initial state
existing before the crosslinking reaction. Crosslinked
bitumen/polymer compositions thus have good mechanical properties,
but their viscosity is very high. In fact, the two characteristics
"mechanical properties" on the one hand, and "fluidity" on the
other hand, are contradictory. The mechanical properties
(elasticity and cohesion), are promoted by long chain lengths,
therefore by crosslinking of the polymer chains. Fluidity is
promoted by a short chain length, therefore by an absence of
crosslinking or a weak crosslinking of the polymer chains.
According to the applications envisaged, it is necessary to find a
good compromise between mechanical properties and fluidity by
adjusting the rate or the nature of the crosslinking.
PRIOR ART
[0004] Crosslinking according to the prior art is usually
irreversible crosslinking based on the formation of covalent bonds
between the polymer chains. Thus, one of the crosslinkings most
used in the field of bitumens is sulphur crosslinking or
vulcanization. In sulphur crosslinking, more or less short sulphur
chains (in general having 8 to 2 atoms of sulphur) covalently bond
the polymer chains. By altering the chemical nature of the donor of
the sulphur and/or the polymer, the temperature, the concentration
of the polymer and/or of the sulphur donors, the Applicant has thus
developed and patented a large number of crosslinked
bitumen/polymer compositions having clearly improved properties
with respect to bitumen without polymers and with respect to the
non-crosslinked bitumen/polymer physical mixture. Among the
Applicant's patents, there can be mentioned the following
references in particular: FR2376188, FR7818534, EP0799280,
EP0690892.
[0005] Novel thermoreversibly crosslinked polymers have recently
been developed. Most of the thermoreversible crosslinking is
carried out using thermoreversible covalent bonds. There are also
thermoreversible crosslinkings which are carried out via
coordination bonds or ionic bonds.
[0006] Thus, JP 11106578 describes the modification of a polyolefin
by an acid anhydride which reacts in the presence of alcohols to
form thermoreversible ester bonds. EP 870793 describes a mixture of
a first polymer having at least two acid functions and a second
polymer having at least two amine functions so as to form stable
amide groups at a low temperature which can be dissociated at a
high temperature. FR2558845 describes the reaction between a
divinyl ether and a copolymer bearing acid functions. The acyl
obtained is stable at a low temperature and decomposes when the
temperature is increased. Other thermoreversibly crosslinked
polymers involve polymers comprising carboxylic acid units which
bond reversibly to metals (JP 50139135, JP 51019035, JP 56014573).
Others still involve labile ionic bonds between acid groups and
amine groups (JP 52065549, JP57158275).
OBJECTIVES OF THE INVENTION
[0007] In these circumstances, the present invention relates to
obtaining polymers capable of being thermoreversibly crosslinked in
an organic medium, these polymers being capable of use in
bitumen/polymer compositions which will themselves be
thermoreversibly crosslinked. Another objective of the invention is
to propose bitumen/polymer compositions having the properties of
reversibly crosslinked bitumen/polymer compositions at operating
temperatures, in particular with respect to elasticity and/or
cohesion, and having a reduced viscosity at processing
temperatures. Another objective of the invention is to propose a
simple process for the preparation of thermoreversibly crosslinked
bitumen/polymer compositions.
BRIEF DESCRIPTION
[0008] The Applicant company has developed novel thermoreversible
crosslinked bitumen/polymer compositions based on a novel family of
graft polymers. The bitumen/polymer compositions obtained have the
properties of conventional crosslinked bitumen/polymer compositions
at operating temperatures, and the properties of non-crosslinked
bitumen/polymer compositions at processing temperatures. Thus, the
invention relates firstly to a graft polymer GP comprising a
polymer main chain and at least one side graft linked to the
polymer main chain, the polymer main chain being obtained from at
least one diene unit, preferably conjugated diene and the graft
comprising a branched, linear or saturated hydrocarbon chain,
having at least 18 carbon atoms.
[0009] Preferably, the branched, linear or saturated hydrocarbon
chain with at least 18 carbon atoms has the general formula
C.sub.nH.sub.2n+1, where n represents an integer greater than or
equal to 18, preferably varying from 18 to 110. The graft polymer
GP results from the reaction between at least one reactive function
of a polymer P and a reactive function of a graft G, the reactive
functions of the polymer P and the graft G being chosen from double
bonds, epoxides, acid anhydrides, carboxylic acids, esters, amides,
thiols, alcohols and amines. The main chain of the polymer P
comprises double bonds.
[0010] Preferably, the polymer P results from the copolymerisation
of conjugated diene units and aromatic monovinyl hydrocarbon units.
The conjugated diene units are chosen from those comprising 4 to 8
carbon atoms per monomer, for example butadiene,
2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene,
1,3-pentadiene and 1,3-hexadiene, chloroprene, carboxylated
butadiene, carboxylated isoprene, in particular butadiene, and
their mixtures. The aromatic monovinyl hydrocarbon units are chosen
from styrene, o-methyl styrene, p-methyl styrene, p-tert-butyl
styrene, 2,3 dimethyl styrene, .alpha.-methyl styrene, vinyl
naphthalene, vinyl toluene, vinyl xylene, and similar or their
mixtures, in particular styrene.
[0011] Preferably, the polymer main chain of the polymer P
comprises reactive double bonds, in particular pendant vinyl double
bonds originating from the 1-2 addition of conjugated diene units,
in particular butadiene units. The polymer P has a styrene content
by weight of 5% to 50%. The polymer P has a butadiene content by
weight of 50% to 95%. The polymer P has a content by weight of
pendant vinyl double-bond units originating from the 1-2 addition
of butadiene from 5% to 50%.
[0012] In a variant of the invention, the graft G has the general
formula C.sub.nH.sub.2n+1--XH where X represents a sulphur atom, an
oxygen atom or the NH group and n represents an integer varying
from 18 to 110. In another variant of the invention the graft G has
the general formula
C.sub.nH.sub.2n+1--(OCH.sub.2CH.sub.2).sub.m--XH where X represents
a sulphur atom, an oxygen atom or the NH group, n represents an
integer varying from 18 to 110 and m represents an integer varying
from 1 to 20.
[0013] Preferably, the graft polymer GP is obtained by reaction
between at least one double bond of polymer P, in particular a
pendant vinyl double bond originating from the 1-2 addition of a
conjugated diene unit of polymer P and a reactive function of a
graft G chosen from the thiol, alcohol or amine functions.
Preferably, the graft polymer GP is obtained by reaction between at
least one double bond of polymer P, in particular a pendant vinyl
double bond originating from the 1-2 addition of a butadiene unit
of polymer P and a thiol function, preferably terminal, of a graft
G. Preferably, the graft polymer GP is obtained by reaction between
at least one double bond of polymer P, in particular a pendant
vinyl double bond originating from the 1-2 addition of a butadiene
unit of polymer P and a graft G of general formula
C.sub.nH.sub.2n+1--XH where X represents a sulphur atom, an oxygen
atom or an NH group and n represents an integer varying from 18 to
110. The graft polymer GP comprises at least two grafts per main
polymer chain.
[0014] The invention also relates to the use of at least one graft
polymer as defined above in bitumen in order to obtain a
bitumen/polymer composition. The invention then relates to
bitumen/polymer compositions comprising at least said graft polymer
and at least one bitumen. The content of graft polymer GP by weight
with respect to the bitumen is from 0.1 to 30%, preferably 1 to
10%. The bitumen/polymer composition comprises moreover at least
one flux (fluxing agent). The bitumen is chosen from atmospheric
distillation residues, vacuum distillation residues, visbroken
residues, blown residues, de-asphalting residues, mixtures and
combinations thereof.
[0015] The invention relates moreover to a process for the
preparation of thermoreversibly crosslinked bitumen/polymer
compositions. Two preparation processes are envisaged. In the
so-called "ex situ" process the graft polymer GP is introduced into
the bitumen. In the so-called "in-situ" process, the polymer P and
the graft G are introduced into the bitumen, the grafting reaction
taking place in the bitumen.
[0016] The ex situ preparation process is such that:
[0017] a) a bitumen is introduced into a receiving vessel equipped
with mixing means, and the bitumen is taken to a temperature
comprised between 90 and 220.degree. C., preferably between 140 and
180.degree. C.,
[0018] b) from 0.1 to 30%, preferably 0.1 to 10% by mass of a graft
polymer GP according to the invention with respect to the mass of
bitumen is introduced,
[0019] c) the composition is heated at a temperature comprised
between 90 and 220.degree. C., preferably between 140 and
180.degree. C., under stirring, until a homogeneous final
bitumen/polymer composition is obtained.
[0020] The in situ preparation process is such that:
[0021] a) a bitumen is introduced into a receiving vessel equipped
with mixing means, and the bitumen is taken to a temperature
between 90 and 220.degree. C., preferably between 140 and
180.degree. C.,
[0022] b) from 0.1 to 30%, preferably 0.1 to 10% by mass of a
polymer P and 0.1 to 30%, preferably 0.1 to 10% by mass of a graft
G with respect to the mass of bitumen are introduced,
[0023] c) the composition is heated at a temperature comprised
between 90 and 220.degree. C., preferably between 140 and
180.degree. C., under stirring, until a homogeneous final
bitumen/polymer composition is obtained.
[0024] Finally, the invention relates to the use of bitumen/polymer
compositions according to the invention in order to produce
bituminous binders, capable of being implemented as they are, in
anhydrous form, in emulsion form or in fluxed bitumen form. These
bituminous binders can then be combined in a mixture with
aggregates in order to provide surface dressings, hot mixes, cold
mixes, cold-cast mixes or gravel emulsions. Applications of the
bitumen/polymer compositions according to the invention are capable
of use in highway applications or industrial applications in order
to produce wearing courses, sealing membranes, membranes or
impregnation layers.
DETAILED DESCRIPTION
[0025] The graft polymer GP according to the invention is a graft
polymer. By graft polymer is meant a polymer which comprises a
polymer main chain and side grafts bonded to this chain. The grafts
are bonded directly to the main chain of the polymer. The polymer
main chain is obtained by polymerisation of several monomers. The
grafts are then grafted to the polymer main chain, after
polymerisation of the latter, by chemical reaction. The result is a
covalent bond between the grafts and the polymer main chain. The
graft polymers according to the invention are thus obtained by
polymerization, then grafting of the grafts, and not by
polymerization of monomers already comprising grafts.
[0026] The graft polymer GP according to the invention results from
the reaction between at least one reactive function of a polymer P
and a reactive function of a graft G. The reactive functions
present on the polymer P and/or on the graft G are chosen from
double bonds, epoxides, acid anhydrides, carboxylic acids, esters,
amides, thiols, alcohols and amines. In particular, the reactive
functions present on the polymer are chosen from double bonds.
Preferably, the reactive functions present on the graft G are
chosen from epoxides, acid anhydrides, carboxylic acids, esters,
amides, thiols, alcohols and amines, preferably thiols, alcohols
and amines, preferably thiols.
[0027] The reactive function(s) present on the polymer P is/are
situated along the polymer P chain while the reactive function(s)
of the graft G is/are preferably terminal i.e. situated at the ends
of the molecule. Preferably the graft G has only one terminal
reactive function while the polymer P has several reactive
functions. The grafts are bonded directly to the polymer main chain
by reaction between their reactive functions, via a covalent
bond.
[0028] The polymers P according to the invention are obtained from
at least one diene unit (or monomer), preferably a conjugated
diene. Thus, the polymers can result from the homopolymerisation of
diene units only, preferably conjugated diene. In these polymers,
along the polymer chain, several double bonds are present,
resulting from the homopolymerization of the diene units,
preferably conjugated diene. Such polymers are for example
polybutadienes, polyisoprenes, polyisobutenes, polychloroprenes,
but also butyl rubbers obtained by concatenation of isobutene and
isoprene copolymers. Copolymers or terpolymers can also be present,
obtained from diene units such as butadiene, isoprene, isobutene,
2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene,
chloroprene, carboxylated butadiene or carboxylated isoprene
units.
[0029] The polymers can also result from copolymerisation or
terpolymerization of diene units, preferably conjugated diene, and
other units containing other reactive functions. These reactive
functions will be chosen for example from double bonds, epoxides,
acid anhydrides, carboxylic acids, esters, amides, thiols, alcohols
and amines, in particular double bonds. Thus the polymers can be
obtained from diene units, preferably conjugated diene and units
such as vinyl acetate, methyl acrylate, butyl acrylate, maleic
anhydride, glycidyl methacrylate, glycidyl acrylate, norbornene
units.
[0030] Polymers such as ethylene/propene/diene (EPDM) terpolymers,
acrylonitrile/butadiene/styrene (ABS) terpolymers can be used. The
polymers according to the invention obtained from at least one
diene unit (or monomer), preferably conjugated diene, can also be
hydrogenated after polymerization. The preferred polymers P are the
polymers which have double bonds along their main chain. Preferred
polymers are those resulting exclusively from the copolymerization
of conjugated diene units and aromatic monovinyl hydrocarbon
units.
[0031] Among the conjugated diene units, there can be mentioned for
example, those comprising 4 to 8 carbon atoms per monomer, such as
butadiene, 2-methyl-1,3-butadiene (isoprene),
2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and 1,3-hexadiene,
chloroprene, carboxylated butadiene or carboxylated isoprene. The
preferred conjugated diene units are butadiene units. Among the
aromatic monovinyl hydrocarbon units, there can be mentioned for
example, styrene, o-methyl styrene, p-methyl styrene,
p-tert-butylstyrene, 2,3 dimethyl-tyrene, .alpha.-methyl styrene,
vinyl naphthalene, vinyl toluene, vinyl xylene. The preferred
aromatic monovinyl hydrocarbon units are styrene units.
[0032] The reactive functions present on the polymer P after the
polymerization reaction are preferably double bonds. According to
the type of polymerization of the conjugated diene units via a 1-2
addition or via a 1-4 addition, the reactive double bonds of
polymer P are of two types. The first results from the 1-4 addition
of the conjugated dienes and the second from the 1-2 addition of
the conjugated dienes. The double bonds originating from the 1-2
addition of the conjugated dienes are pendant vinyl double bonds.
The reactive functions present on the polymer P after the
polymerization reaction are preferably pendant vinyl double bonds
originating from the 1-2 addition of conjugated diene units. In
particular, the reactive functions present on the polymer P after
the polymerization reaction are pendant vinyl double bonds
originating from the 1-2 addition of butadiene units.
[0033] The preferred polymers P are styrene- and butadiene-based
block copolymers. Advantageously, they have a styrene content by
weight ranging from 5% to 50% and a butadiene content by weight
ranging from 50% to 95%. Advantageously, the polymer P has a
pendant vinyl double-bond units originating from the 1-2 addition
of butadiene content by weight ranging from 5% to 50%. The average
molecular mass by weight of the polymer P can be comprised, for
example, between 10,000 and 600,000 daltons and is situated
preferably between 30,000 and 400,000 daltons.
[0034] The graft G comprises a branched, linear or saturated
hydrocarbon chain, of at least 18 carbon atoms, preferably at least
22 carbon atoms, preferably at least 30 carbon atoms. Preferably
the saturated hydrocarbon chain of the graft is linear. The graft G
comprises a hydrocarbon chain of general formula C.sub.nH.sub.2n+1,
where n represents an integer greater than or equal to 18,
preferably varying from 18 to 110, preferably varying from 18 to
90, preferably varying from 18 to 50, preferably varying from 20 to
40, preferably 25 to 30. Preferably, the graft G has the general
formula C.sub.nH.sub.2n+1--XH where X represents a sulphur atom, an
oxygen atom or an NH group and n represents an integer varying from
18 to 110, preferably varying from 18 to 90, preferably varying
from 18 to 50, preferably varying from 20 to 40, preferably 25 to
30.
[0035] When X is a sulphur atom, the graft G has the general
formula C.sub.nH.sub.2n+1--SH, and n varies from 18 to 110,
preferably 18 to 90, preferably 18 to 50, preferably 20 to 40,
preferably 25 to 30. When X is an oxygen atom, the graft G has the
general formula C.sub.nH.sub.2n+1--OH, and n varies from 18 to 110,
preferably 18 to 90, preferably 18 to 50, preferably 20 to 40,
preferably 25 to 30. When X represents the NH group, the graft G
has the general formula C.sub.nH.sub.2n+1--NH.sub.2, and n varies
from 18 to 110, preferably 18 to 90, preferably 18 to 50,
preferably 20 to 40, preferably 25 to 30.
[0036] Preferably, the graft G of general formula
C.sub.nH.sub.2n+1--XH is a thiol (X=S), chosen for example from the
following thiols: C.sub.18H.sub.37--SH, C.sub.40H.sub.81--SH,
C.sub.70H.sub.141--SH and/or C.sub.90H.sub.181--SH. The graft G can
also have, as general formula, the following general formula:
C.sub.nH.sub.2n+1--(OCH.sub.2CH.sub.2).sub.m--XH where X represents
a sulphur atom, an oxygen atom or an NH group, n represents an
integer varying from 18 to 110 and m represents an integer varying
from 1 to 20, preferably n represents an integer varying from 18 to
90, preferably varying from 18 to 50, preferably varying from 20 to
40, preferably 25 to 30.
[0037] Preferably, the graft G of general formula
C.sub.nH.sub.2n+1--(OCH.sub.2CH.sub.2).sub.m--XH is an alcohol
(X=O), chosen for example from the following alcohols:
[0038]
CH.sub.3--(CH.sub.2).sub.32--(OCH.sub.2CH.sub.2).sub.3--OH,
[0039]
CH.sub.3--(CH.sub.2).sub.49--(OCH.sub.2CH.sub.2).sub.4--OH,
[0040]
CH.sub.3--(CH.sub.2).sub.32--(OCH.sub.2CH.sub.2).sub.11--OH,
[0041]
CH.sub.3--(CH.sub.2).sub.49--(OCH.sub.2CH.sub.2).sub.16--OH.
[0042] According to a preferred embodiment of the invention the
graft polymer GP is obtained by reaction between at least one
double bond of polymer P, in particular a pendant vinyl double bond
originating from the 1-2 addition of a conjugated diene of polymer
P and a function chosen from the thiol, alcohol or amine functions
of the graft G. In particular, the graft polymer GP is obtained by
reaction between at least one pendant vinyl double bond originating
from the 1-2 addition of a conjugated diene unit of polymer P, and
a thiol function, preferably terminal, of a graft G. In particular,
the graft polymer GP is obtained by reaction between at least one
pendant vinyl double bond originating from the 1-2 addition of a
butadiene unit of polymer P, and a thiol function, preferably
terminal, of a graft G.
[0043] More preferably, the graft polymer GP is obtained by
reaction between at least one pendant vinyl double bond originating
from the 1-2 addition of a butadiene unit of polymer P, and a graft
G of general formula C.sub.nH.sub.2n+1--XH where X represents a
sulphur atom, an oxygen atom or an NH group and n represents an
integer varying from 18 to 110, preferably varying from 18 to 90,
preferably varying from 18 to 50, preferably varying from 20 to 40,
preferably 25 to 30. More preferably, the graft polymer GP is
obtained by reaction between at least one pendant vinyl double bond
originating from the 1-2 addition of a butadiene unit of polymer P,
and a graft G chosen from the following thiols:
C.sub.18H.sub.37--SH, C.sub.40H.sub.81--SH, C.sub.70H.sub.141--SH
and/or C.sub.90H.sub.181--SH.
[0044] According to another preferred embodiment of the invention
the graft polymer GP is obtained by reaction between at least one
double bond of polymer P, in particular a pendant vinyl double bond
originating from the 1-2 addition of a conjugated diene of the
polymer P and an alcohol function, preferably terminal, of a graft
G. More preferably, the graft polymer GP is obtained by reaction
between at least one pendant vinyl double bond originating from the
1-2 addition of a butadiene unit of polymer P, and a graft G of
general formula C.sub.nH.sub.2n+1--(OCH.sub.2CH.sub.2)m-OH where n
represents an integer varying from 18 to 110 and m represents an
integer varying from 1 to 20, preferably n represents an integer
varying from 18 to 90, preferably varying from 18 to 50, preferably
varying from 20 to 40, preferably 25 to 30.
[0045] More preferably, the graft polymer GP is obtained by
reaction between at least one pendant vinyl double bond originating
from the 1-2 addition of a butadiene unit of polymer P, and a graft
G chosen from the following alcohols:
[0046]
CH.sub.3--(CH.sub.2).sub.32--(OCH.sub.2CH.sub.2).sub.3--OH,
[0047]
CH.sub.3--(CH.sub.2).sub.49--(OCH.sub.2CH.sub.2).sub.4--OH,
[0048]
CH.sub.3--(CH.sub.2).sub.32--(OCH.sub.2CH.sub.2).sub.11--OH,
[0049]
CH.sub.3--(CH.sub.2).sub.49--(OCH.sub.2CH.sub.2).sub.16--OH.
[0050] The scope of the invention is not exceeded when the polymer
P reacts firstly with a reactive species comprising a function
chosen from the following functions: alkenes, dienes, epoxides,
acid anhydrides, carboxylic acids, esters, carboxylic acids, thiol,
alcohol and/or primary amine and only subsequently with a graft G
as defined in the invention. According to the invention, the
polymer GP comprises at least one side graft. Preferably the
average number of grafts per main polymer chain is greater than
2.
[0051] Preferably, the polymer GP comprises from 3 to 55% in moles
of grafts G, preferably 5 to 35% in moles, more preferably 10 to
20% in moles. Preferably, the polymer GP comprises from 10 to 55%
by mass of grafts G, preferably 15 to 35% by mass, more preferably
17 to 20% by mass. When the polymer GP is a polymer having a high
content by weight of pendant vinyl double-bond units originating
from the 1-2 addition of the butadiene (for example of the order of
30% by mass, instead of 10% by mass for a polymer GP not having a
high content by weight of pendant vinyl double-bond units
originating from the 1-2 addition of the butadiene), the grafting
rate is greater and the polymer GP comprises more grafts G (of the
order of 40% by mass instead of 10% by mass).
[0052] These grafts can all have the same chemical structure or
have different chemical structures within the graft polymer GP.
Grafts having a different chain length can therefore coexist within
a single main polymer chain. Thus, for example, the graft polymer
GP can comprise at least one graft comprising a C.sub.18H.sub.37--
side chain and at least one graft comprising a C.sub.70H.sub.141--
side chain.
[0053] Without being bound by the following theory, these are the
grafts G allowing thermoreversible crosslinking. The crosslinking
results from assembling the graft polymers GP via the grafts G
(more precisely via the hydrocarbon chains of the grafts G). This
assembly allows crystalline areas to be defined between the grafts
G of the graft polymer GP. These crystalline areas are stable at
low temperature. When the temperature increases, these crystalline
areas melt, recrystallizing when the temperature reduces. At low
temperature the interactions of the crystalline areas of the grafts
G bring together the chains of the graft polymer GP which are then
crosslinked. When the crystalline areas of the grafts melt, the
chains of the graft polymer GP move apart, they are no longer
crosslinked.
[0054] Thus, when a bitumen with the graft polymers GP according to
the invention is used as an additive, bitumen/polymer compositions
are obtained which are reversibly, and more particularly
thermoreversibly, crosslinked. By thermoreversible crosslinking of
the bitumen/polymer compositions according to the invention, is
meant a crosslinking demonstrated by the following phenomena:
[0055] at low temperature, for example at working temperatures, the
grafts G of the cograft polymers GP are combined and form
crosslinking points. The polymer network formed confers good
mechanical properties on the bitumen/polymer composition, in
particular with regard to flexibility and cohesion.
[0056] when hot, a temperature increase causes the rupture of the
crosslinking points and as a result the dissociation of the polymer
chains. The polymer network disappears and the bitumen/polymer
composition returns to a low viscosity and therefore a good
fluidity.
[0057] a reduction in temperature allows the crosslinking points to
reform. The phenomenon is thermoreversible.
[0058] The bitumen/polymer compositions according to the invention
are constituted by at least one bitumen and at least one graft
polymer GP. The graft polymers GP introduced into the bitumen have
been described previously. The graft polymers GP represent 0.1 to
30% by weight with respect to the bitumen. According to a preferred
implementation, the graft polymers GP represent from 1 to 10% by
weight with respect to the bitumen, preferably, from 1 to 5% by
weight with respect to the bitumen.
[0059] The bitumen/polymer compositions according to the invention
can contain bitumens of different origins. There can be mentioned
firstly the bitumens of natural origin, those contained in deposits
of natural bitumen, natural asphalt or bituminous sands.
[0060] The bitumens according to the invention are also the
bitumens originating from the refining of crude oil. The bitumens
originate from the atmospheric and/or vacuum distillation of oil.
These bitumens being able to be optionally blown, visbroken and/or
de-asphalted. The bitumens can be bitumens of hard or soft grade.
The different bitumens obtained by the refining processes can be
combined with each other in order to obtain the best technical
compromise. The bitumens used can also be bitumens fluxed by the
addition of volatile solvents, fluxes originating from oil,
carbochemical fluxes and/or fluxes of vegetable origin. The fluxes
used can comprise C.sub.6 to C.sub.24 fatty acids in acid, ester or
amide form in combination with a hydrocarbon cut.
[0061] The invention relates to a process for the preparation of
thermoreversibly crosslinked bitumen/polymer compositions. Two
processes can be envisaged: a so-called ex-situ and a so-called
in-situ process. By ex situ process is meant a process in which the
grafting of the grafts G onto the polymer P is carried out apart
from the bitumen, the polymer GP being obtained apart from the
bitumen.
[0062] Obtaining a bitumen modified according to the so-called ex
situ process comprises the following essential steps:
[0063] a) a bitumen is introduced into a receiving vessel equipped
with mixing means, and the bitumen is taken to a temperature
between 90 and 220.degree. C., preferably between 140.degree. C.
and 180.degree. C.,
[0064] b) from 0.1 to 30% by mass of a graft polymer GP according
to the invention with respect to the mass of bitumen, preferably
0.1 to 10% is introduced.
Throughout the process, the composition is heated at a temperature
between 90 and 220.degree. C., preferably between 140 and
180.degree. C., under stirring, until a homogeneous final
bitumen/polymer composition is obtained.
[0065] It is also envisaged to obtain a modified bitumen according
to a so-called in-situ process where the formation of the cograft
polymer GP according to the invention is carried out in the
bitumen. The so-called in-situ process comprises the following
essential steps:
[0066] a) a bitumen is introduced into a receiving vessel equipped
with mixing means, and the bitumen is taken to a temperature
between 90 and 220.degree. C., preferably between 140.degree. C.
and 180.degree. C.,
[0067] b) from 0.1 to 30%, preferably 0.1 to 10% by mass of a
polymer P is introduced, then from 0.1 to 30%, preferably 0.1 to
10% by mass of a graft G is introduced.
Throughout the process, the composition is heated at a temperature
between 90 and 220.degree. C., preferably between 140 and
180.degree. C., under stirring, until a homogeneous final
bitumen/polymer composition is obtained.
[0068] Various uses of the bitumen/polymer compositions obtained
according to the invention are envisaged, in particular for the
preparation of a bituminous binder, which can in turn be used for
preparing a combination with aggregates, in particular road
aggregates. Another aspect of the invention is the use of a
bituminous composition in various industrial applications, in
particular for preparing a sealing membrane, membrane or
impregnation layer. With regard to highway applications, the
invention relates in particular to bituminous mixes as materials
for the construction and maintenance of road foundations and their
surfacing, as well as for carrying out all road works. Thus, the
invention relates for example to surface dressings, hot mixes, cold
mixes, cold-cast mixes, emulsion gravels, base, binder, bonding and
wearing courses, and other combinations of a bituminous binder and
highway aggregate having particular properties such as anti-rutting
courses, draining mixes, or poured asphalts (mixture of a
bituminous binder and sand-type aggregates).
[0069] With regard to the industrial applications of the bituminous
compositions, there can be mentioned the production of sealing
membranes, anti-noise membranes, insulating membranes, surface
coatings, carpet tiles, impregnation layers, etc. It can be
envisaged to introduce the graft polymer GP according to the
invention into other media other than bitumen such as for example,
adhesives or paints.
EXAMPLES
Preparation of the Polymer GP
[0070] Three polymers GP according to the invention are prepared
from a polymer P which is a styrene/butadiene block copolymer,
having 25% by weight of styrene and 75% by weight of butadiene.
This copolymer has a molecular mass by weight Mw of 128,000 Dalton,
a polymolecularity index Mw/Mn of 1.11 and a content of pendant
vinyl double-bond units originating from the 1-2 addition of
butadiene of 10% by mass with respect to the assembly of butadiene
units. 50 ml of toluene, 2 g of polymer P described above are
introduced into a reactor kept under a nitrogen atmosphere. Then
1.5 g of graft G and 10 mg of AIBN (azobisisobutyronitrile) are
introduced into the reactor; the mixture is heated progressively to
approximately 90.degree. C. under stirring.
[0071] Three grafts are used: C.sub.18H.sub.37--SH (G.sub.1),
C.sub.40H.sub.81--SH (G.sub.2), C.sub.70H.sub.141--SH (G.sub.3).
After 3 to 4 hours, the solution is cooled down to ambient
temperature and the copolymer GP is precipitated using methanol and
acetone. The graft polymers GP.sub.1, GP.sub.2 and GP.sub.3 are
obtained from grafts G.sub.1, G.sub.2 and G.sub.3 respectively.
[0072] Bitumen
[0073] The bitumen is a bitumen of penetration grade 50 1/10 mm the
characteristics of which correspond to the standard NF EN
12591.
[0074] Bitumen/Polymer Compositions C.sub.1, C.sub.2 and C.sub.3
According to the Invention
[0075] Three bitumen/polymer compositions according to the
invention are prepared from the graft polymers GP.sub.1, GP.sub.2
and GP.sub.3 and the bitumen described above (ex-situ process). 35
g of bitumen is introduced into a reactor kept at 180.degree. C.
and equipped with a mechanical stirring system. The bitumen is
heated at 185.degree. C. and stirred for approximately 60 minutes.
Then 1.8 g of the graft polymer GP.sub.1, GP.sub.2 or GP.sub.3
obtained above is added. The mixture forms during a period of 4
hours under stirring. The bitumen/polymer compositions C.sub.1,
C.sub.2 and C.sub.3 are obtained, from the graft polymers GP.sub.1,
GP.sub.2 and GP.sub.3 respectively.
[0076] Preparation of the Polymer GP In-Situ and Bitumen/Polymer
Compositions C.sub.4, C.sub.5, and C.sub.6 According to the
Invention
[0077] Three further bitumen/polymer compositions according to the
invention are prepared, starting from the in-situ preparation
process. 35 g of bitumen described above is introduced into a
reactor heated at 185.degree. C. and stirred. The bitumen is heated
and stirred for approximately 60 minutes. Then, 1.8 g of the
polymer P (styrene-butadiene bi-block copolymer, having 25% by
weight of styrene and 75% by weight of butadiene described above)
and 1.8 g of graft G are added.
[0078] Three grafts are used: C.sub.18H.sub.37--SH (G.sub.1),
C.sub.40H.sub.81--SH (G.sub.2), C.sub.70H.sub.141--SH (G.sub.3).
The mixtures are stirred for approximately 4 hours. The
compositions C.sub.4, C.sub.5 and C.sub.6 are obtained, from the
grafts G.sub.1, G.sub.2 and G.sub.3 respectively.
[0079] A Control Bitumen/Polymer Composition T.sub.1
[0080] An irreversibly-crosslinked bitumen/polymer composition is
prepared as follows: 35 g of the above bitumen is introduced into a
reactor. The bitumen is heated at 185.degree. C. and stirred for
approximately 60 minutes. Then 1.8 g of the styrene-butadiene
bi-block copolymer, having 25% by weight of styrene and 75% by
weight of butadiene described above is added. The mixture is
stirred and heated at 185.degree. C. for approximately 4 hours.
Then 50 mg of sulphur is added. The mixture is stirred and heated
at 185.degree. C. for 1 hour 30 minutes. The Table below shows the
physical characteristics of the compositions according to the
invention and of the control composition.
[0081] Results
TABLE-US-00001 C.sub.1 C.sub.2 C.sub.3 T.sub.1 Penetrability (0.1
mm) (1) 52 37 32 43 RBT (.degree. C.) (2) 51.8 74.2 83.8 61.6
Viscosity at 80.degree. C. 35.0 38.2 58.10 59.00 Viscosity at
100.degree. C. 6.10 5.50 11.40 14.94 Viscosity at 120.degree. C.
1.60 1.10 2.82 4.27 Viscosity at 140.degree. C. 0.59 0.41 0.97 1.48
Viscosity at 160.degree. C. 0.26 0.18 0.42 0.63 Viscosity at
180.degree. C. 0.14 0.10 0.22 0.37 Viscosity at 200.degree. C. 0.08
0.05 0.12 0.18 Max. elongation at 5.degree. C. (%) (3) 701 520 150
697 Stress (daN/cm.sup.2) (3) 1.0 1.3 1.3 1.3 (1) According to
standard EN 1426 (2) Ring and Ball temperature, according to
standard EN 1427 (3) Traction test at 5.degree. C., according to
standard NF T 66-038, with a stretching rate of 500 mm/min.
[0082] The results of this table show that the viscosities at
80.degree. C. to 200.degree. C. of the bitumen/polymer compositions
according to the invention are always less than those of the
control composition T.sub.1. The bitumen/polymer compositions
according to the invention from 80.degree. C. are therefore less
viscous than a sulphur-crosslinked bitumen/polymer composition. Low
viscosities at processing temperatures are thus reached using the
bitumen/polymer compositions according to the invention.
[0083] Moreover, it is noted that the elastic properties of the
bitumen/polymer compositions according to the invention depend on
the chain length of the graft grafted on the polymer. The best
elasticity/viscosity compromise is obtained for the compositions
C.sub.1 and C.sub.2 in which the elastic properties are of the same
order of magnitude as those of a sulphur-crosslinked
bitumen/polymer composition (maximum elongation under traction and
stress equivalent for C.sub.1, C.sub.2 and T.sub.1). At operating
temperatures, the bitumen/polymer compositions according to the
invention, in particular C.sub.1 and C.sub.2, are therefore elastic
while having a reduced viscosity at processing temperatures.
Similarly, it is noted that the Ring and Ball temperatures of the
bitumen/polymer compositions according to the invention depend on
the chain length of the graft grafted on the polymer. In the case
of the compositions C.sub.2 and C.sub.3, these values are even
greater than that of the sulphur-crosslinked control T.sub.1.
* * * * *