Continuous synthesis method for a modified diene elastomer, facility for implementing same
View Patent ↗A continuous method for synthesizing a diene elastomer includes modifying the diene elastomer in a functionalizing device by: a kinetic model according to which the ratio of the rate constants is greater than 1, and a flow represented by a residence time distribution in the functionalizing device that is expressed according to equations 1 or 3: (i) in a functionalizing device having at least one tubular continuous reactor or having at least one cascade of at least two stirred reactors, E 1 ( t ) = 1 2 ( P πθ 1 t ) 1 2 e - P ( θ 1 - t ) 2 4 θ 1 t Eq 1 (ii) in a functionalizing device that is a combination of the device (i) and of a device having at least one continuous stirred reactor, having a residence time distribution characterized by the following equation: E 2 ( t ) = e ( - t θ 2 ) θ 2 Eq 2 the device (ii) having a residence time distribution characterized by the equation 3 below, which is the result of the convolution of equations 1 and 2: E 12 ( t ) = ∫ 0 t E 1 ( t - T ) E 2 ( T ) d T E 12 ( t ) = ∫ 0 t 1 2 ( P πθ 1 ( t - T ) ) 1 2 e - P ( θ 1 - ( t - T ) ) 2 4 θ 1 ( t - T ) e ( - T θ 2 ) θ 2 d T Eq 3
1. A method for the continuous synthesis of a modified diene elastomer, comprising the steps:
of anionic polymerization of at least one conjugated diene monomer in the presence of a polymerization initiator,
of modifying the diene elastomer in a functionalizing device, by bringing the living diene elastomer bearing an active site obtained in the previous step into contact, in a single step, with a non-polymerizable functionalizing agent comprising a trialkoxysilane group, and optionally a function capable of interacting with a reinforcing filler,
the modification comprising three reactions in series
Reactions
Mechanism
R1
PLi + A k 1 fi PA
R2
PLi + PA k 2 fi P 2 A
R3
PLi + P 2 A k 3 fi P 3 A
where
A represents the functionalizing agent,
PLi represents a living elastomer chain,
PA represents the chain-end functionalized elastomer,
P 2 A represents the coupled elastomer,
P 3 A represents the three-arm star-shaped elastomer, and
k i represents the rate constant of the reaction R i , that are carried out according to the following rate law:
Reactions
Rate of reaction
R1
V 1 = k 1 [PLi][A]
R2
V 2 = k 2 [PLi][PA]
R3
V 3 = k 3 [PLi][P 2 A]
where
k 1 , k 2 and k 3 are the rate constants respectively of the reactions R1, R2 and R3 (expressed in (m 3 /mol)·s −1 ),
[PLi] is the concentration of living chains (expressed in mol/m 3 ),
[A] is the concentration of modifying agent A (expressed in mol/m 3 ),
[PA] is the concentration of chain-end functionalized elastomer (expressed in mol/m 3 ),
[P 2 A] is the concentration of coupled elastomer (expressed in mol/m 3 ),
[P 3 A] is the concentration of the three-arm star-shaped elastomer (expressed in mol/m 3 ),
with a ratio of the rate constants, defined as:
K
=
k
1
k
2
=
k
2
k
3
,
of greater than 1, and
the residence time distribution in a functionalizing device (i) or (ii) is expressed respectively according to equations 1 or 3 below:
(i) in a functionalizing device having at least one tubular continuous reactor or having at least one cascade of at least two stirred reactors,
E
1
(
t
)
=
1
2
(
P
πθ
1
t
)
1
2
e
-
P
(
θ
1
-
t
)
2
4
θ
1
t
Eq
1
in which:
P is the dimensionless parameter of resistance to dispersion,
θ 1 is the residence time defined as the reactor volume/total volume flow rate ratio, equal to at least 0.1 minute and at most to 10 minutes,
t is the variable time of the residence time distribution,
(ii) in a functionalizing device that is a combination of the device (i) and of a device having at least one continuous stirred reactor, having a residence time distribution characterized by the following equation:
E
2
(
t
)
=
e
(
-
t
θ
2
)
θ
2
Eq
2
in which:
θ 2 is the residence time defined as the reactor volume/total volume flow rate ratio, between 0 and 60 minutes,
t is the variable time of the residence time distribution,
the device (ii) having a residence time distribution characterized by the equation 3 below, which is the result of the convolution of equations 1 and 2:
E
12
(
t
)
=
∫
0
t
E
1
(
t
-
T
)
E
2
(
T
)
d
T
E
12
(
t
)
=
∫
0
t
1
2
(
P
πθ
1
(
t
-
T
)
)
1
2
e
-
P
(
θ
1
-
(
t
-
T
)
)
2
4
θ
1
(
t
-
T
)
e
(
-
T
θ
2
)
θ
2
d
T
Eq
3
in which:
θ 1 and θ 2 are the residence times as defined above,
P is the dimensionless parameter of resistance to dispersion,
t is the variable time of the residence time distribution,
T is the integration variable.
2. The method for the continuous synthesis of a modified diene elastomer according to claim 1 , wherein K is greater than or equal to 10.
3. The method according to claim 1 , wherein P is greater than 6.9.
4. The method according to claim 3 , wherein P is greater than or equal to 9.6.
5. The method according to claim 1 , wherein the functionalizing agent is represented by formula 1:
in which,
R is a C 1 -C 18 cyclic or non-cyclic, saturated or unsaturated, aliphatic or C 6 -C 18 aromatic divalent hydrocarbon radical,
X is a hydrogen atom or a function capable of interacting with a reinforcing filler,
the R′ radicals, which are substituted or unsubstituted, identical or different, represent a C 1 -C 10 .
6. The method according to claim 5 , wherein X is a function capable of interacting with a reinforcing filler selected from cyclic or non-cyclic, primary, secondary or tertiary amines, isocyanates, imines, cyano compounds, thiols, carboxylates, epoxides and primary, secondary or tertiary phosphines.
7. The method according to claim 6 , wherein the function capable of interacting with a reinforcing filler is a secondary amine optionally protected by a trialkylsilyl group or a tertiary amine, the nitrogen atom being substituted by C 1 -C 10 alkyl radicals.
8. The method according to claim 7 , wherein the functionalizing agent is selected from 3-(N,N-dimethylaminopropyl)trimethoxysilane, 3-(N,N-dimethylaminopropyl)triethoxysilane, 3-(N,N-diethylaminopropyl)trimethoxysilane, 3-(N,N-diethylaminopropyl)triethoxysilane, 3-(N,N-dipropylaminopropyl)trimethoxysilane, 3-(N,N-dipropylaminopropyl)triethoxysilane, 3-(N,N-dibutylaminopropyl)trimethoxysilane, 3-(N,N-dibutylaminopropyl)triethoxysilane, 3-(N,N-dipentylaminopropyl)trimethoxysilane, 3-(N,N-dipentylaminopropyl)triethoxysilane, 3-(N,N-dihexylaminopropyl)trimethoxysilane, 3-(N,N-dihexylaminopropyl)triethoxysilane, 3-(hexamethyleneaminopropyl)trimethoxysilane and 3-(hexamethyleneaminopropyl)triethoxysilane.
9. The method according to claim 7 , wherein the nitrogen atom is substituted by C 1 -C 4 alkyl radicals.
10. The method according to claim 9 , wherein the nitrogen atom is substituted by a methyl or ethyl radical.
11. The method according to claim 6 , wherein the function capable of interacting with a reinforcing filler is a cyclic amine that forms a heterocycle containing a nitrogen atom and at least one carbon atom.
12. The method according to claim 11 , wherein the cyclic amine contains 2 to 6 carbon atoms.
13. The method according to claim 5 , wherein R is a C 1 -C 10 aliphatic, linear or branched, divalent hydrocarbon radical.
14. The method according to claim 13 , wherein R is a C 3 linear hydrocarbon radical.
15. The method according to claim 1 , further comprising subsequent to the modification step, a step of deprotection when the function capable of interacting with the reinforcing filler is a protected primary or secondary amine, protected thiol or protected primary or secondary phosphine function.
16. The method according to claim 1 , further comprising subsequent to the modification step, a step of hydrolysis of the modified elastomer obtained in the preceding step.
17. The method according to claim 1 , wherein the molar ratio of the functionalizing agent to the polymerization initiator has a value ranging from 0.40 to 0.75.
18. The method according to claim 1 , wherein the molar ratio of the functionalizing agent to the polymerization initiator has a value ranging from 0.15 to 0.40.
19. The method according to claim 1 , wherein the molar ratio of the functionalizing agent to the polymerization initiator has a value greater than or equal to 0.75.
20. A modified diene elastomer obtained according to the continuous synthesis method as described in claim 1 .
21. The method according to claim 1 , wherein the residence time θ 1 is at most 5 minutes and the residence time θ 2 is between 5 and 50 minutes.