Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F136/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
  • C08F136/02—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
  • C08F136/04—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
  • C08F136/06—Butadiene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F110/00—Homopolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F110/04—Monomers containing three or four carbon atoms
  • C08F110/08—Butenes

Definitions

• the present invention relates to a process for obtaining a homopolymer of 1,3-butad ⁇ ene in the presence of one or more mono-olefin (s) of 4 carbon atoms, for example from a C4 cut of steam cracking naphtha, this homopolymer having microstructure and macrostructure characteristics making it suitable for use in tire treads.
• the C4 naphtha steam cracking cuts essentially contain, according to a mass fraction typically between 20 and 50%, 1,3-butad ⁇ ene and, according to a mass fraction between 70 and 40%, mono-olefins comprising butene-1 , butene-2 and isobutene.
• a C4 cut is obtained having a mass fraction of 1,3-butad ⁇ ene which is respectively smaller or higher, in proportion to the mass fraction of the mono-olefins.
• French patent document FR-A-2 496 673 presents another process for the selective polymerization of butadiene from a C4 cut of steam cracking of naphtha, which consists in using a catalytic system based on a hthiated initiator.
• the object of the present invention is to remedy this drawback, and it is achieved in that the applicants have unexpectedly discovered that a catalytic system based on at least:
• a conjugated diene monomer - a salt of one or more rare earth metals (metals having an atomic number between 57 and 71 in the periodic table of Mendeleev's elements) of an organic phosphoric acid, said salt being in suspension in at least one inert, saturated hydrocarbon solvent of aliphatic or alicyclic type which is included in said catalytic system,
• an alkylating agent consisting of an aluminum alkyl of formula A1R 3 or HA1R 2 , where R is an alkyl group, and
• a halogen donor consisting of an alkylaluminum halide, allows the selective polymerization of 1,3-butadiene, in the presence of one or more monoolefins of 4 carbon atoms, with a high catalytic activity which is analogous to that relating to the homopolymé ⁇ sation of 1,3-butadiene in the absence of mono-olefin by means of the same catalytic system, for obtaining a polybutadiene having characteristics of microstructure and macrostructure which are very close to those presented by a polybutadiene obtained in the absence of mono-olefin by means of said catalytic system.
• this polymerization is carried out at a temperature ranging from 25 ° C. to 100 ° C.
• NIR near infrared assay technique
• the polymerization process according to the invention makes it possible to obtain, with high activity, polybutadienes having rates of concatenations c ⁇ s-1, 4, measured using the near infrared assay technique (“NIR” technique, see annex 1), which are greater than 95.0%, as well as inherent viscosities, measured at 25 ° C at a concentration of 0.1 g / dl in toluene (see annex 3 for the measurement method), which are for example greater than 2 dl / g and, even more advantageously, which are greater than 3 dl / g.
• NIR near infrared assay technique
• the molar ratio (alkylating agent / rare earth salt) which characterizes said catalytic system has a value ranging from 1 to 15, for obtaining polybutadienes with an improved catalytic activity which have rates of concatenation. 1.4, measured by this near infrared assay technique, which may be greater than 97.0%. More advantageously, said molar ratio has a value ranging from 1 to 10, in particular from 1 to 5.
• the catalytic systems according to the invention make it possible to obtain, in the presence of said mono-olefin (s), polybutadienes having a polydispersity index Ip, measured by the chromatography technique size exclusion (see Annex 2), which is less than 2.
• the mass ratio (mono-olefin (s) / butadiene-1,3) is equal to or greater than 50%. Even more advantageously, this mass ratio is equal to or greater than 100% and, even more advantageously, said mass ratio is equal to or greater than 150%.
• said mono-olefin (s) include butene-1 and / or butene-2 and / or isobutene
• the process for obtaining according to the invention a homopolymer of 1,3-butadiene comprises the reaction of said catalytic system in the presence of a C4 cut of steam cracking of naphtha containing, according to a mass fraction between 20 and 50%, butad ⁇ ene-1,3 and, according to a mass fraction between 70 and 40%, mono-olefins comprising in particular butene-1 and butene-2.
• said rare earth salt is a t ⁇ s [bis (2-ethylhexyl) phosphate] of rare earth (s) and, even more preferably, this rare earth salt is very [b ⁇ s (2-ethylhexyl) phosphate] of neodymium.
• this catalytic system comprising the rare earth metal (s) at a concentration equal to or greater than 0.005 mol / 1 and, even more preferably, according to a concentration belonging to a range ranging from 0.010 mol / 1 to 0.060 mol / 1.
• alkylating agent which can be used in the catalytic system according to the invention, mention may be made of aluminum alkyls such as:
• t ⁇ alkylaluminiums for example tnisobutylaluminium, or
• dialkylalummium hydrides for example dnsobutylaluminium hydride.
• this alkylating agent preferably consists of dnsobutylaluminum hydride (called HDiBA in the remainder of this description).
• halogen donor which can be used in the catalytic system according to the invention, use is preferably made of alkyl aluminum monohalides and, even more preferably, diethyl aluminum chloride (called CDEA in the remainder of this description).
• the molar ratio (halogen donor / rare earth salt) belongs to a range ranging from 2.0 to 3.5.
• the molar ratio (conjugated diene monomer / salt) belongs to a range ranging from 15 to 70.
• said conjugated diene monomer is butadiene.
• conjugated diene monomer which can be used to "preform" the catalytic system according to the invention use is preferably made of 1, 3-butad ⁇ ene.
• 2-methyl 1, 3-butad ⁇ ene or isoprene
• 2, 3-d ⁇ (C1 to C5 alkyl) 1, 3-butad ⁇ ene such as for example 2, 3 d ⁇ methyl-1, 3- butad ⁇ ene, 2, 3-methyl-1, 3-butad ⁇ ene, 2-methyl 3-ethyl 1, 3-butad ⁇ ene
• said rare earth salt consists of a non-hygroscopic powder having a slight tendency to agglomerate at room temperature
• the inert hydrocarbon solvent in which said rare earth salt is in suspension is an aliphatic or alicyclic solvent of low molecular weight, such as cyclohexane, methylcyclohexane, n-heptane, or a mixture of these solvents.
• the solvent used for the suspension of the rare earth salt is a mixture of an aliphatic solvent of high molecular weight comprising a paraffinic oil, for example petrolatum oil, and a low molecular weight solvent such as those mentioned above (for example methylcyclohexane).
• a paraffinic oil for example petrolatum oil
• a low molecular weight solvent such as those mentioned above (for example methylcyclohexane).
• This suspension is produced by dispersive grinding of the rare earth salt in this paraffinic oil, so as to obtain a very fine and homogeneous suspension of the salt.
• the process for preparing said catalytic system consists of 1 - in a first step, carrying out a suspension of said rare earth salt in said solvent,
• FIG. 1 is a graph illustrating the evolution of the conversion rate (%) of 1,3-butad ⁇ ene to polybutadiene as a function of time (min.), On the one hand, for a first “control” polymerization test carried out in absence of mono-olefin and, on the other hand, for a first polymerization test according to the invention carried out in the presence of butene-1 as mono-olefin;
• - Fig 2 is a graph illustrating the evolution of the conversion rate (%) of 1,3-butad ⁇ ene to polybutadiene as a function of time (min), on the one hand, for a second polymerization test
• - Fig. 3 is a graph illustrating the evolution of the conversion rate (%) of 1,3-butad ⁇ ene to polybutadiene as a function of time (mm), on the one hand, for a third “control” polymerization test carried out in the absence of mono-olefin and, on the other hand, for a third polymerization test according to the invention carried out in the presence of isobutene as mono-olefin;
• - Fig. 4 is a graph illustrating the evolution of the conversion rate (%) of 1,3-butad ⁇ ene to polybutadiene as a function of time (mm), on the one hand, for a fourth “control” polymerization test carried out in the absence of mono-olefin and, on the other hand, for a fourth polymerization test according to the invention carried out in the presence of butene-1 as mono-olefin;
• - Fig. 5 is a graph illustrating the evolution of the conversion rate (%) of 1,3-butad ⁇ ene to polybutadiene as a function of time (min), on the one hand, for a fifth “control” polymerization test carried out in the absence of mono-olefin and, on the other hand, for a fifth polymerization test according to the invention carried out in the presence of butene-1 and butene -2 as mono-olefin, and
• FIG. 6 is a graph illustrating the evolution of the conversion rate (%) of 1,3-butadiene to polybutadiene as a function of time (min), on the one hand, for a sixth “control” polymerization test carried out in the absence of mono-olefin and, on the other hand, for a sixth polymerization test according to the invention carried out in the presence of butene-2 as mono-olefin.
• the pH of the solution measured at 25 ° C., is corrected by adding approximately 0.55 1 of sodium hydroxide to 2 moles per liter. The final pH is almost 4.5.
• the phosphate salt of neodymium thus obtained is recovered by sedimentation and it is washed with a mixture of 45 liters of demineralized water and 15 liters of acetone for 15 minutes.
• the phosphate salt of neodymium is then recovered by centrifugation.
• the pH of the “mother” waters is between 3 and 4 at 25 ° C. These “mother” waters are colorless and clear
• the qualitative analytical test for chlorides is almost negative (the reaction is: NaCl AgN0 + 3 (middle HN0 3) ⁇ AgCl + -I NaN0 3).
• the neodymium salt thus washed is dried in an oven at 60 ° C., under vacuum and with a stream of nitrogen for 72 hours.
• steps b) and c) can be carried out without the use of acetone.
• the measurements of neodymium content were carried out after acid mineralization of the salt by the wet method, either on a sand bath in the open system, or in the microwave in the closed system.
• EDTA ethylene diamine tetracetic acid
• the atomic emission spectrometry technique coupled to an induced plasma is an elementary analysis technique based on the observation of the lines emitted by atoms arriving in an excited state at the sem of a plasma.
• the emission lines which have been used for the analysis of neodymium correspond to wavelengths of 406.109 nm and 401.225 nm
• the catalytic system according to the invention comprises a phosphate salt of neodymium as synthesized according to paragraph 1) above, which is in suspension in an inert hydrocarbon solvent of low molecular weight (consisting of methylcyclohexane, “MCH” for short) after).
• the neodymium salt is contacted with 448 ml of MCH at 30 ° C for 30 minutes.
• the catalytic solution is stored under a nitrogen atmosphere in a freezer, at a temperature of -15 ° C.
• the polymerizations are carried out at 50 ° C. for a variable duration.
• cyclohexane is introduced into this Steinie bottle which is bubbled for 10 minutes with nitrogen to remove the impurities, 5 ml of butadiene, a variable amount of butene-1 or butene-2 or isobutene ( see ⁇ 1), 2), 3) and 4) below) then a variable quantity of the catalytic system prepared according to ⁇ I. above.
• Butene-1, butene-2 and isobutene come from the company "Aldnch” (listed respectively under the references 29.505-1, 36.335-9 and 29.546-9). All of these butenes were passed over alumina to remove impurities.
• the mass ratio S / M (cyclohexane solvent / butadiene monomer-1.3) is understood according to the tests between 8.3 and 12.6 To be able to compare the tests with each other we have placed our in conditions which are such that the ratio volume (volume of butadiene / (volume of cyclohexane + volume of butene)) is constant.
• the amount of neodymium catalytic base varies from 173 ⁇ mol to 432.9 ⁇ mol per 100 g of butadiene, according to the test carried out.
• antioxidant N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine
• Table 1 mentions the polymerization conditions followed, on the one hand, for a first “control” test Tl in which the polymerization medium is devoid of mono-olefin and, on the other hand, for a first test according to invention II in which the polymerization medium comprises butene-1 as mono-olefin.
• a catalytic system according to the invention which comprises said conjugated diene monomer, said rare earth salt of an organic phosphoric acid in suspension in said inert and saturated hydrocarbon solvent, said alkylating agent and said donor halogen, allows to homopolymerize butadiene-1,3 in the presence of butene-1 in a mass ratio (butene-1 / butadiene-1,3) greater than 150%, with a high catalytic activity similar to that relating to homopolymerization of 1,3-butadiene in the absence of butene-1 by means of the same catalytic system (see the similarity of the polymerization kinetics curves of tests II and T1), to obtain a polybutadiene having characteristics of microstructure and macrostructure very close to those presented by the "control" polybutadiene of the Tl test.
• the inherent viscosity of the polybutadiene in test II is very close to that of the polybutadiene in test Tl, these viscosities being both greater than 3.0 dl / g, and that the polydispersity index Ip of polybutadiene of test II is less than 2.0, like the index Ip of the polybutadiene of test T1, these characteristics making the polybutadiene of test II suitable for use in tire treads just like the polybutadiene of test Tl.
• Table 2 mentions the polymerization conditions followed, on the one hand, for a second T2 "control" test in which the polymerization medium is devoid of mono-olefin and, on the other hand, for a second test according to invention 12 in which the polymerization medium comprises butene-2 as mono-olefin.
• a catalytic system according to the invention which comprises said conjugated diene monomer, said rare earth salt of an organic phosphoric acid suspended in said inert and saturated hydrocarbon solvent , said agent alkylation with a molar ratio (alkylating agent / rare earth salt) equal to 6 and said halogen donor, makes it possible to homopolymenate butad ⁇ ene-1,3 in the presence of isobutene according to a mass ratio (isobutene / butadiene-1,3) greater than 100%, with a high catalytic activity similar to that relating to the homopolymé ⁇ sation of butad ⁇ ene-1,3 in the absence of isobutene by means of the same catalytic system (see the similarity of the curves of kinetics of polymerization of tests 13 and T3), for obtaining a polybutadiene having microstructure and macrostructure characteristics very close to those presented by the "control" polybutadiene of test T3
• the rate of cis-1,4 chains in the polybutadiene of test 13 is close to that of the polybutadiene of test T3, these rates being both greater than 97.0%. It will also be noted that the viscosity inherent of the polybutadiene of test 13 is very close to that of the polybutadiene of test T3, these viscosities being both greater than or equal to 2.8 dl / g, and that the polydispersity index Ip of the polybutadiene of the test 13 is less than 2.0, like the polybutadiene index Ip of test T3, these characteristics making the polybutadiene of test 13 suitable for use in tire treads like the polybutadiene from test T3
• Table 6 below indicates the polymerization conditions followed, on the one hand, for a sixth "control" test T6 in which the polymerization medium is devoid of mono-olefin and, on the other hand, for a sixth test according to invention 16 in which the polymerization medium comprises butene-2 as mono-olefin.
• APPENDIX 1 Determination of the microstructure of the polybutadienes obtained.
• NMR near infrared
• Size exclusion chromatography makes it possible to physically separate the macromolecules according to their size in the swollen state on columns filled with porous stationary phase.
• the macromolecules are separated by their hydrodynamic volume, the largest being eluted first.
• the equipment used is a “WATERS alliance” chromatograph.
• the elution solvent is tetrahydrofuran, the flow rate is 1 ml / min, the system temperature of 35 ° C and the duration of the analysis is 30 min.
• a set of two “styragel HT6E” columns is used in series.
• the injected volume of the polymer sample solution is 100 ⁇ l.
• the detector is a "WATERS 2410" differential refractometer and the software for operating the chromatographic data is the "WATERS MILLENIUM" system.
• the inherent viscosity is determined by measuring the flow time t of the polymer solution and the flow time t 0 of toluene in a capillary tube.
• step 1 preparation of the measurement solution at 0.1 g / dl in toluene
• n ° 2 measurement of the flow times t of the polymer solution and t 0 of toluene at 25 ° C in a "Ubbelohde" tube,
• C concentration of the toluene solution of polymer in g / dl; t: flow time of the toluene polymer solution in hundredths of seconds; t 0 : toluene flow time in hundredths of seconds; ⁇ inh : inherent viscosity expressed in dl / g.

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• 2003
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