FR3015979A1 - PROCESS FOR THE CONTINUOUS SYNTHESIS OF A FUNCTIONALIZED POLYISOPRENE - Google Patents

Abstract

The present invention relates to a process for the continuous synthesis of functionalized polyisoprene with a high cis content, characterized in that it comprises the simultaneous stages of: • continuous polymerization in a highly concentrated medium of isoprene in the presence of a catalytic system of coordination, until at least 60% conversion is achieved in a sized polymerization reactor so that the standard deviation of the residence time distribution function in said reactor is greater than the average residence time divided by 2√3; To continuously functionalize the pseudo-living polyisoprene obtained at the end of the polymerization, by reaction with a functionalizing agent in a self-cleaning type mixer. This synthetic process, applicable in a highly concentrated medium, has increased productivity, in particular by enabling a high conversion rate of up to 100% and functionalization ratios of at least 70% to be achieved, and allows flexibility in his conduct.

Description

PROCESS FOR THE CONTINUOUS SYNTHESIS OF A FUNCTIONALIZED POLYISOPRENE The present invention relates to a method of synthesis in a concentrated medium of modified polyisoprene with a high degree of functionalization. The invention is particularly applicable to the continuous production of modified polyisoprene. Since fuel savings and the need to preserve the environment have become a priority, it is desirable to produce mixtures with good mechanical properties and as low a hysteresis as possible so that they can be used in the form of for use in the manufacture of various semi-finished products used in the composition of tires In order to achieve the objective of reducing hysteresis, the structure of the diene polymers and copolymers must in particular be modified by means of functionalisers for the purpose to obtain a good interaction between the polymer thus modified and the load, whether carbon black or another reinforcing filler. There is a vast literature concerning the functionalization of polymers obtained by anionic polymerization. Functionalization can take place either during the initiation of polymerization by means of an initiator bearing the function to be incorporated in the elastomeric chain, or during a post-polymerization reaction by means of a functionalization agent. Agents for introducing all kinds of functions within the polymer are known to those skilled in the art and widely described. In certain areas of the tire, for example for the manufacture of tires suitable for carrying heavy loads, it is known to use natural rubber because of the reduced hysteretic losses that this elastomer has. In order to get as close as possible to the performance of natural rubber, it is essential to have synthetic polyisoprene with a high cis content. This type of polyisoprene can not be obtained by anionic polymerization. The high cis polyisoprenes are essentially prepared by coordination catalysis polymerization. There is also a very extensive literature dealing with this type of catalysis. The functionalization of these high-cis polyisoprenes is less widespread because of the very nature of the catalytic systems used. Some authors have described the functionalization of polymers obtained by coordination catalysis. Mention may in particular be made of the documents WO 0134658 A1, US6624256 B2, JP2009120758, JP2009120756, JP2009120757, EP 1,939,221 A1 and EP 1,873,168 A1. Some mention high functionalization levels, greater than 75%, for polymers obtained by mass or semi-polymerization. such as EP 1,939,221 A1. Others disclose functionalized synthetic polyisoprenes such as JP2009120758 which discusses functionalization to interact with silica and JP2009120756 and JP2009120757 which discuss functionalization to interact with silica. carbon black. Nevertheless all these documents deal with discontinuous polymerization (or batch in English). But a discontinuous process is not always productive and sufficiently competitive and economical for industrial production. If it is quickly mentioned in EP 1,939,221 A1 with reference to WO2005087824, the possibility of carrying out the process described continuously, the low conversion rates or the use of several polymerization reactors to increase the conversion to an acceptable level, make the unattractive process. Moreover, in order to reduce the manufacturing costs and to reinforce the economic interest of the polymerization of isoprene, it appears advantageous to carry out the semi-mass polymerization in the presence of volatile aliphatic hydrocarbon solvent (whose temperature of boiling is below 40 ° C at atmospheric pressure), or in the absence of solvent. The advantages of such polymerizations are diverse and known to those skilled in the art. However, it is a major disadvantage of mass or semi-mass polymerization (hereinafter also referred to as polymerization in a highly concentrated medium). This results in the appearance of a physical phenomenon that could degrade the nature of the polyisoprene obtained and lead to uncontrollable situations in an industrial production. Indeed, the vaporization of a portion of the liquid isoprene and the volatile solvent, under the effect of the energy of the polymerization reaction, leads, from a certain concentration of polyisoprene in the reaction medium, to excessive expansion of the reaction medium. Under such operating conditions, it is no longer possible to control the thermal reaction and the polyisoprene may be denatured. This is the reason why some authors prefer low monomer conversion rates to avoid this phenomenon, for example in US 3,770,710 or in WO2005087824.

The technical problem to be solved by the invention is to have a competitive, economical and flexible synthesis process, adaptable to industrial production, to produce a polyisoprene high cis functionalised. An object of the invention is also to provide a method for producing a polyisoprene high cis functionalised having a high degree of functionalization. Another objective of the invention is to provide a method for synthesizing, in a highly concentrated medium, high functionalized cis-functionalized polyisoprene exhibiting increased productivity by avoiding the phenomenon of expansion of the reaction medium and thus allowing flexibility in the conduct of the process in particular in a wide range of temperatures. The present invention solves the technical problem and achieves these objectives in that it proposes a continuous process, particularly suitable for economically interesting industrial production with increased competitiveness. The invention indeed proposes a continuous process for synthesizing a functionalized polyisoprene comprising a continuous isoprene polymerization step in a highly concentrated medium by coordination catalysis and a step of continuous functionalization of the pseudo-living polyisoprene obtained at the same time. polymerization step. The invention makes it possible to improve the isoprene polymerization conditions in a highly concentrated medium in order to be able to reach high conversion rates without the appearance of an expansion phenomenon of the reaction medium. The invention also makes it possible to achieve high functionalization rates greater than or equal to 70%. The invention also provides the energy and environmental advantages of polymerization in a highly concentrated medium and the use of a volatile solvent, as well as the possibility of carrying out the process over a wide range of reaction temperatures. including low temperatures. Thus, the subject of the invention is a process for the continuous synthesis of a modified polyisoprene comprising a mass or semi-mass polymerization step in which the pseudo-living polyisoprene with high cis content is synthesized and a functionalization step or modification in which the pseudo-living polyisoprene reacts with a specific functionalizing agent. The invention also relates to an installation for the implementation of such a method.

The first object of the invention is a process for continuously synthesizing a functionalized polyisoprene comprising the following simultaneous steps, related to the polymerization: a) continuously introducing into a polymerization reactor equipped with a gas phase and equipped with at least one shaker and a discharge device, at least i. a catalytic coordination system based on - isoprene, as pre-forming monomer, - a rare earth metal salt of an organic phosphoric acid, or a rare earth metal salt of a carboxylic acid ; a saturated or unsaturated inert hydrocarbon solvent whose boiling point is less than 40 ° C. at atmospheric pressure; an alkylating agent consisting of a trialkylaluminium of formula A1R3, in which R represents an alkyl radical preferably having from 1 to 10 carbon atoms, preferably trioctylaluminium; and - a halogen donor consisting of an alkylaluminum halide, the alkyl radical preferably having from 1 to 8 atoms; ii. isoprene as the conjugated diene monomer to be polymerized, and, iii. from 0% to 70% by weight of a volatile organic solvent, calculated with respect to the total mass of isoprene and solvent; b) continuously polymerize the isoprene, using the means necessary to achieve a conversion of at least 60% at the limit of the first third of the reaction volume of the polymerization reactor; c) stirring the polymerization medium by the continuous movement of at least one stirring member around a rotary axis; d) continuously discharging the pseudo-living polyisoprene paste resulting from the polymerization; the standard deviation of the residence time distribution function in the polymerization reactor being greater than the average residence time divided by 2-V3; - Related to the functionalization: e) continuously convey this paste to a mixer with a gas phase, a stirring device to at least one mobile stirrer and a discharge device; f) continuously introducing into the kneader a functionalizing agent having the formula A-R1-B with A denoting a group capable of reacting on the reactive end of the pseudovivant elastomer, R1 denoting an atom or a group of atoms forming a bond between A and B, and B denoting a function capable of reacting with a reinforcing filler; g) continuously functionalizing the pseudo-living polyisoprene by reaction with the functionalizing agent in said kneader; h) continuously discharging the functionalized polyisoprene paste from the previous step; i) recovering the functionalized polyisoprene.

Inasmuch as the process according to the invention proceeds continuously, it should be understood that steps (a) to (i) take place simultaneously once the polymerization reactor has been supplied. In the present description, the terms "highly concentrated medium" and "mass or semi-mass" are used interchangeably to have the same meaning. In the present description, the terms "solvent" and "diluent" are used interchangeably to have the same meaning. In this description, any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (i.e., terminals a and b excluded) while any Range of values referred to as "from a to b" means the range of values from a to b (i.e. including the strict limits a and b).

In the present description, the term "high cis content" or "high cis ratio" in relation to the elastomer means a molar ratio of 1,4-cis units of at least 95% by relative to the elastomer. In the present description, the term "pseudo-living" in relation to the elastomer means that the elastomer has all or part of these chain ends reactive, especially vis-à-vis functionalising agents. In the present description, the rate of functionalization, which is an average degree of functionalization, must be understood as the average percentage of functionalized elastomer chains.

It should be noted that the combination of the flow characteristics and the conversion is one of the essential elements of the invention which allows the continuous polymerization process to contribute to solving the technical problem posed for the polymerization in a highly concentrated, adaptable medium. economically advantageous industrial production with satisfactory productivity, more particularly by avoiding the phenomenon of expansion of the reaction medium. According to one particular embodiment of the synthesis process of the invention, the polymerization is carried out continuously with a quantity of solvent not exceeding 70% by weight of the total mass of isoprene and solvent, the amount of solvent being be for example at least 10% by weight, or even at least 30% by weight, and at most 60% by weight, or even at most 55% by weight of the total mass of isoprene and solvent . According to another embodiment of the invention, the polymerization is carried out without addition of polymerization solvent. The choice of the polymerization reactor is, because of these possibilities of implementation, a particularly important aspect of the process according to the invention. Indeed, it is desired to polymerize isoprene in highly concentrated media. According to the invention, by highly concentrated media, is meant an isoprene concentration in the solvent + isoprene mixture of at least 30% by weight, this concentration can reach 100% by weight in the absence of solvent. In addition, it is desired to polymerize until obtaining high conversion rates in the limit of the first third of the reaction volume of the polymerization reactor of at least 60% and up to 100%. The viscosity of the polymerization medium consisting essentially of polyisoprene, isoprene and optionally solvent can reach high values. The inherent viscosity of the diene elastomer depends on its nature. It has a minimum value of at least 1.5 dl / g, or even at least 4 dl / g, especially for polyisoprenes obtained by coordination catalysis. However, the inherent viscosity preferably does not exceed 10 dl / g or 7 dl / g. The inherent viscosity is determined according to the method described in Appendix 1.

The stirring within the polymerization reactor must ensure mixing of this highly viscous medium to allow the synthesis of a polyisoprene of constant and homogeneous quality. In addition to compatibility with high viscosities, the reactor must be suitable for use in continuously polymerizing isoprene and allow for highly concentrated or even mass flow, such as the standard deviation of the time distribution function. in the polymerization reactor is greater than the average residence time divided by 2-V3. The stirring mobile allows continuous stirring of the reaction medium. It can be of varied form and is adapted to the reactor technology. Many types of agitation mobiles can be found commercially. By way of example, the stirring device may be a sigma (or "Z") type of blade or another type of blade as described in the David B. Todd book, Mixing of Highly Viscous Fluids, Polymers, and Pastes, Handbook of Industrial Mixing: Science and Practice, Paul EL, Atiemo-Obeng VA, and SM Kresta, Editors. 2004, John Wiley and Sons. Page 998, Page 1021.

When the reactor is equipped with at least two agitating mobiles, these can be counter-rotating or co-rotating. In addition, they can be tangential or nested. According to certain configurations, the polymerization reactor is equipped with a stirrer. Thus, this type of reactor may be formed of a vessel, a stirring device and a discharge device. For example, mention may be made of the reactor marketed by the company LIST AG under the name single-arm kneader or single-shaft kneader, as reactor suitable for the invention. According to other configurations, the polymerization reactor is equipped with two stirring rods. According to the configurations described above, the polymerization reactor may be formed of a tank, its stirring system and a discharge device. According to preferred configurations, the polymerization reactor is more particularly Z-arm kneader technology. By Z-arm kneading technology, more particularly is meant a mixer or kneader formed of a tank equipped with two Z-shaped arms, each driven by independently about a rotary axis, preferably horizontal. The two Z-arms are then preferably moved in counter-rotating rotation so as to fill the emptying device at the bottom of the tank. By way of example, this reactor according to the invention is marketed under various names such as: - mixers with sigma blades - screw discharge, or in English "sigma blades mixerdischarge screw type", marketed by the company Battaggion SPA, extruder-kneaders, marketed by Aachener Misch-und Knetmaschinenfabrik Peter Küpper GmbH & Co. KG, double Z mixers with extrusion screws or in English "double-z-kneader" with extrusion screw ", sold by Hermann Linden Maschinenfabrik GmbH & Co. KG., - extruder mixers, sold by Aaron Process Equipment Company.

The polymerization reactor is provided with a gas phase allowing the evacuation of the polymerization heat by vaporization of a part of the reaction medium. The volume ratio of the gas phase to the reaction medium depends on the type of reactor used and its determination is within the reach of those skilled in the art. According to one embodiment of the invention, the polymerization is carried out in bulk. In this case, there is no addition of polymerization solvent. According to other embodiments of the invention, the polymerization is carried out in semi-mass. The medium then comprises an inert hydrocarbon polymerization solvent, generally aliphatic or alicyclic low molecular weight, especially for environmental reasons. In order to lower the energy cost of the industrial polyisoprene preparation process when the polymerization is carried out in solution, the polymerization is preferably carried out in the presence of a volatile inert hydrocarbon solvent, that is to say having a point d boiling below 40 ° C, which may be for example an aliphatic or alicyclic hydrocarbon having at most 5 carbon atoms. Indeed, the recovery step of the synthesized polyisoprene is facilitated by its low boiling point. As such, mention may be made of C5 light alkanes such as n-pentane, 2-methylbutane, 2,2-dimethylpropane or a mixture of these solvents. Other inert C 5 aliphatic hydrocarbon solvents, such as 1-pentene, 2-pentene, 2-methyl-but-1-ene and 3-methyl-but-1, may also be mentioned. -ene, 2-methyl-but-2-ene, or a mixture of these solvents. As the polymerization solvent, it is preferred to use an alkane, more preferably n-pentane. The solvent can be introduced directly into the reactor. It may also be mixed beforehand with at least one of the other components introduced into the polymerization reactor, in particular the isoprene to be polymerized. This last option constitutes a preferential implementation according to the invention. According to one implementation of the method of the invention combinable with the previous one, the isoprene can be introduced in the form of a petroleum fraction comprising it. According to the invention, in the context of the coordination catalysis polymerization of isoprene, a multi-component catalyst system based on at least one is used. isoprene, as a pre-forming monomer, a rare earth metal salt of an organic phosphoric acid, or a rare earth metal salt of a carboxylic acid; a saturated or unsaturated inert hydrocarbon solvent whose boiling point is less than 40 ° C. at atmospheric pressure; an alkylating agent consisting of a trialkylaluminium of formula A1R3, in which R represents an alkyl radical preferably having from 1 to 10 carbon atoms, and a halogen donor consisting of a halogenide of alkylaluminium, the alkyl radical having preferably from 1 to 8 atoms; this catalytic system comprising the rare earth metal in a concentration equal to or greater than 0.005 mol / l. By the expression "based on" used to define the constituents of the catalytic system is meant the product or the reaction products of these constituents after premixing of all or part of the constituents, or, where appropriate, after pre-forming and / or aging of the catalytic system. The catalyst system may be prepared batchwise or continuously according to the process described in WO-A-2007/045417. According to one implementation of the process of the invention, upstream of the polymerization reactor, a continuous synthesis plant of the catalytic system continuously feeds the polymerization reactor. The catalytic system may be preformed before the polymerization reaction, that is to say by contacting all the various components of the catalyst system with each other, including preforming isoprene, in one or more steps for a given time, generally between 0 and 120 minutes at a temperature ranging from 10 ° C to 80 ° C. Then, the resulting catalyst system is contacted with the isoprene to be polymerized in the volatile solvent. The catalytic system can also be introduced directly into the reactor or be premixed with at least one of the other components that supply the polymerization reactor. Such a catalytic system is the subject of application PCT / EP2013 / 075437. A first constituent element of the multi-component catalytic system according to the invention is isoprene, as pre-forming monomer.

According to variants of the invention, the molar ratio (preforming isoprene / rare earth salt) has a value ranging from 5 to 100, preferably from 10 to 90 and even more preferably from 15 to 70, or even 25 to 50 A second constituent element of the multi-component catalytic system according to the invention is the metal salt of rare earth (s). By rare earth metal is meant any element of the family of lanthanides, or yttrium, or else scandium. As a preference, the rare earth element is an element of the family of lanthanides, more preferably neodymium. As the rare earth metal salt that can be used in this catalytic system, it is advantageous to use: according to a first variant of the invention: a rare earth salt of an organic phosphoric acid, or, according to a second variant of the invention: a rare earth salt of a carboxylic acid. When the rare earth metal salt is a rare earth salt of an organic phosphoric acid, or rare earth organophosphate, it may be a phosphoric acid diester of general formula (R'0) (R "O) P0 (OH), in which R 'and R ", which may be identical or different, represent a saturated or unsaturated C 1 -C 10 alkyl, C 6 -C 12 aryl or C 7 -C 22 alkylaryl radical. Among these phosphoric acid diesters, R 'and R ", identical or different, are preferably an n-butyl, isobutyl, n-pentyl, isopentyl, 2,2-dimethylhexyl, 1-ethylhexyl, 2-ethylhexyl or tolyl radical. Of these organophosphates, bis (2-ethylhexyl) phosphate is preferred, or a mixture of several rare earth metal salts of organic phosphoric acid may be used as the salt. .

As the metal salt (s) rare earth (s) of an organic phosphoric acid used according to the invention, mention may be made preferably tris [bis (2-ethylhexyl) phosphate] neodymium. The rare earth salt (s) of an organic phosphoric acid may alternatively be used in the form of a solution in a hydrocarbon aliphatic or cycloaliphatic solvent, preferably identical to the solvent of the catalytic system. As a rare earth salt (s) of a phosphoric acid, it is possible for example to use a commercially available rare earth organophosphate or also synthesized according to the invention described in WO2009083480 A1. Advantageously of this variant of the invention, the solution of the rare earth salt (s) of a phosphoric acid comprises, besides the residual organophosphoric acid in the preparation of the salt, an organic or inorganic acid of 25 kPa. ° C less than 2.5 as described in the patent application of the Applicants WO 10/133608. When the rare earth metal salt is a carboxylate, it may be a linear or branched aliphatic carboxylic acid carboxylate having 6 to 20 carbon atoms in the linear chain, or aromatic carboxylic acids having one or more aromatic nuclei, substituted or unsubstituted. By way of example, mention may be made of neodecanoate (versatate), 2-ethylhexanoate, octoate, hexanoate, linear or branched, or even naphthenates, which may or may not be substituted. Of the carboxylates, 2-ethylhexanoate and neodecanoate are preferred. It is also possible to use, as a salt, a mixture of several metal salts of rare earth (s) of carboxylic acid. As rare earth metal salts of a carboxylic acid that may be used in the catalytic system according to the invention, mention may preferably be made of neodymium organocarboxylates, and preferentially neodymium tris [2-ethylhexanoate] or tris [ versatate] of neodymium. The rare earth salt (s) can be prepared in a manner known per se. The catalytic system according to the invention comprises the rare earth metal in a concentration equal to or greater than 0.005 mol / l. Preferably, the concentration of rare earth metal in the catalytic system is from 0.010 mol / l to 0.1 mol / l and even more preferably from 0.02 to 0.08 mol / l. Another constituent element of the catalytic system according to the invention is an inert hydrocarbon solvent, saturated or unsaturated, whose boiling temperature is below 40 ° C at atmospheric pressure. As such, there may be mentioned C5 light alkanes such as n-pentane, 2-methylbutane, 2,2-dimethylpropane or a mixture of these solvents. There may also be mentioned other C5 hydrocarbon solvents, inert, unsaturated, of the aliphatic type, such as 1-pentene, 2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, or a mixture of these solvents. Preferably, the inert hydrocarbon solvent whose boiling temperature is below 40 ° C at atmospheric pressure is an alkane, more preferably npentane. Indeed, the alkanes are readily available commercially thus ensuring a consistency in the quality and composition of the solvent, as well as a lower cost of production. According to a particularly advantageous embodiment of the invention, the solvent of the catalytic system is identical to the volatile polymerization solvent. Indeed, this implementation reduces the cost of production because it does not require an expensive additional step of separating solvents and reduces the number of storage devices. According to this variant, the solvent having a boiling point below 40 ° C allows a less energy-intensive industrial process because the removal of the volatile solvent, once the synthesized polyisoprene, is facilitated by its low boiling point. Another constituent element of the multi-component catalytic system according to the invention is an alkylating agent. This alkylating agent consists of a trialkylaluminium, the alkyl radical being C1-C10. As examples of trialkylaluminiums, trimethylaluminium, triethylaluminium, tri-n-propylaluminium, triisopropylaluminium, tri-n-butylaluminium, tri-t-butylaluminium, tri-n-pentylaluminium, triethylaluminum may be mentioned. n-hexylaluminum, tri-n-octylaluminum, tricyclohexylaluminum.

According to the invention, the choice of these alkylating agents makes it possible to have a catalytic system in the form of a homogeneous and clear solution. The absence of insoluble particles plays a major role in reducing costs by minimizing or even eliminating the contribution of the catalytic system to deposits in the plant and its fouling. Indeed, the use in a continuous process of a cloudy catalyst solution, leads to a fouling of the injection pipe of the catalytic system and the manufacturing unit, and eventually capping some pipes or malfunction of certain devices such as flow control devices, filters, valves, valves and other pumps. The repeated passage of a non-homogeneous substance can lead to fouling of these devices and clogging of certain pipes and eventually to stops of the production line which generally represent an additional cost for the implementation of the continuous process. It has been demonstrated that triisobutylaluminium does not contribute to achieving the cost reduction objectives of the invention, and that alkylation agents are therefore excluded. According to a preferred embodiment, the alkylating agent consists of trioctylaluminium. According to variants of the invention, it will be noted that the molar ratio (alkylating agent / rare earth salt (s)) in said catalytic system advantageously has a value of at least 1 and at most 50 According to certain variants of the process of the invention, this ratio is at most 30 or even at most 15. According to other variants of the process of the invention, this ratio is at least 4. The last constituent element of the multi-component catalytic system according to the invention is a halogen-donating agent. Among these agents, mention may be made of alkylaluminium halides. Mention may be made, for example, of alkylaluminum monohalides and dihalides and mixtures thereof, especially diethylaluminum chloride, diethylaluminium bromide and ethylaluminum dichloride. Diethylaluminum chloride is more particularly preferred. According to variants of the invention, the molar ratio (halogen donor / rare earth salt) has a value ranging from 0.5 to 5, preferably from 2 to 3.6 and even more preferably from 2.5 to 3. 2. Embodiments of the invention consist of combinations of the various aspects described above with respect to the composition of the catalytic system and in particular the combinations of the variants and / or preferential aspects thereof, be it the nature of the components or their proportion. Thus, an advantageous embodiment of the invention is a multi-component catalytic system, as defined above, which fulfills at least one of the following four conditions and preferably the four - the rare earth salt (s). (s) is a neodymium organophosphate, preferentially neodymium tris [bis (2-ethylhexyl) phosphate]; the inert hydrocarbon solvent is an alkane, preferentially n-pentane; the alkylating agent is trioctylaluminum; and the halogen donor is an alkylaluminium halide, preferably diethylaluminum chloride. Such catalytic systems make it possible in particular to obtain homopolymers of isoprene exhibiting a rate of 1,4-cis linkages (measured by the "NIR" technique of the near-infrared assay, explained below) which is greater than 95%. or at least 97%, which can be described as a high rate (high rate) in 1,4-cis units. According to alternative embodiments of the synthesis method according to the invention, it is possible to introduce into the polymerization reactor, by a flow independent of the introduction of the catalytic system used for the polymerization reaction, a predetermined additional amount of from at least one alkylaluminium compound of formulas A1R3 or HA1R2 or R ".A1R'3, in which R and R 'represent an alkyl group of 1 to 20 carbon atoms, saturated or unsaturated, preferably from 1 to 12 carbon atoms, R "represents an allyl group, n an integer inclusive of 1 to 3. Such variants are described in particular in the documents WO2006133757, EP 1845118, WO 10/069511, WO10 / 069805. According to an advantageous implementation of this variant of polymerization process, the alkylaluminium compound is different from the trialkyaluminium compound used to prepare the catalytic system. According to another implementation, this variant of the polymerization process, the alkylaluminium compound is identical to the trialkyaluminium compound. used to prepare the catalytic system As an alkylaluminium compound, mention may be made of alkylaluminiums such as: trialkylaluminiums such as, for example, trimethylaluminium, triethylaluminium, tri-n-propylaluminium, triisopropylaluminium, tri-n-butylaluminium, tri-t-butylaluminum, triisobutylaluminum, tri-n-pentylaluminium, tri-n-hexylaluminium, tricyclohexylaluminium, preferably triisobutylaluminium or dialkylaluminium hydrides such as, for example, diethylaluminum hydride, hydride of diisopropylaluminum, di-n-propylaluminum hydride, hydride of d iisobutylaluminum, di-n-octylaluminum hydride, di-n-butylaluminum hydride, preferably diisobutylaluminum hydride.

Advantageously, the molar ratio (alkylaluminium compound added in shifted / trialkylaluminium in the catalytic system) varies from 1/20 to 50/1, preferably varies from 1/15 to 30/1 and even more preferably from 1/10 to 20/1. . It will be noted that the addition of the alkylaluminium compound before polymerization makes it possible to overcome the fluctuations in time of the impurities due to the solvents and monomers injected at the line inlet and not to penalize, because of these fluctuations, the activity of the catalytic system. This variant embodiment of the invention thus makes it possible to minimize the dispersion of the characteristics of the elastomer obtained. This variant is combinable with all the variants and implementations of the invention, preferred or not, described above or below. According to one implementation of the polymerization process of the invention, all the components of the initial reaction medium, that is to say the isoprene to be polymerized, the optional solvent, the catalytic system and, if appropriate, the additional alkylaluminium can be introduced individually directly into the polymerization reactor.

According to other implementations of the process of the invention, at least two components of the initial reaction medium are not introduced individually directly into the polymerization reactor. The mixture of said components may be provided by various means known to those skilled in the art with static, dynamic or ultrasonic mixers. The mixture can be temperature-conditioned before entering the polymerization reactor. A second step of the process according to the invention concerns the polymerization of isoprene until reaching (1) a high degree of conversion of at least 60%, in limit of the first third of the reaction volume of the polymerization reactor with (2 ) a standard deviation of the residence time distribution function in the polymerization reactor greater than the average residence time divided by 2-V3. According to the process of the invention, the degree of conversion of isoprene to polyisoprene is at least 60%, in limit of the first third of the reaction volume of the polymerization reactor. The volume of the polymerization reactor is understood to mean the volume existing in the reactor between the point of entry of the reactants and the outlet of the reactor, excluding the discharge device. This 60% conversion rate, associated with the specific characteristic relating to the residence time distribution function of the invention, is essential to overcome the formation of foam and eliminate the phenomenon of expansion of the reaction medium. Indeed, below 60% and without satisfying the condition relating to the residence time distribution function of the invention, the formation of bubbles is observed which rapidly leads to an uncontrollable expansion of the reaction medium. To achieve this necessary conversion rate of at least 60%, the skilled person has many levers or technical means that can vary in multiple combinations. Among these various technical levers include the reaction temperature, the concentration of monomer in the reaction medium, the concentration of polymerization catalyst in the reaction medium, the average residence time .... The means to implement to achieve at least 60% conversion to the limit of the first third of the reaction volume of the polymerization reactor are within the reach of those skilled in the art. The simple instruction to reach a minimum conversion limit, in this case at least 60% in limit of the first third of the reaction volume of the polymerization reactor, constitutes for him an identification of the combinations of means to be implemented to carry out this instruction. . The conversion rate can be determined in various ways known to those skilled in the art. For example, the conversion rate can be determined from a measurement made on a sample taken at the limit of the first third of the reaction volume of the polymerization reactor, for example by gas chromatography (GC). The residual isoprene concentration (not converted in the sample) is measured. By difference between the concentration of isoprene introduced into the polymerization reactor (G) and the residual isoprene concentration measured in the sample taken (Cr), the mass conversion rate is determined as being: X% mass = 100 * [(C, - Cr) 1 with: X% mass: mass conversion rate; C, isoprene concentration introduced into the polymerization reactor; Cr: residual isoprene concentration measured in the sample taken; Preferably, this conversion rate is at least 80% and more preferably still 85% to 100%, for increasing productivity.

The process of the invention is also characterized by the flow conditions in the reactor during the polymerization reaction. The characterization of these flows by a residence time distribution function is such that the standard deviation of the residence time distribution function Ci is greater than the average residence time divided by 2-V3. More particularly, the standard deviation of the residence time distribution function is greater than the average residence time divided by 2. The residence time distribution function in the polymerization reactor can be determined in a manner known per se by a skilled person. For example, it can be determined by modeling the experimental points obtained by measuring, by Gas Chromatography, the evolutions of the concentration of a tracer at the outlet of the reactor, following a very rapid injection, of this tracer, according to a mode of introduction. by impulse of a chemically inert product according to the principle described in the book Jacques Villermaux, Engineering of the chemical reaction: design and operation of the reactors. Editors. 1993, TEC & DOC - LAVOISIER, Page 170-172. The combination of these two characteristics of conversion rate and flow is one of the essential elements of the invention. Thus, according to the invention, a synthetic process is used in a very concentrated and continuous medium, polyisoprene having increased productivity, and remarkable flexibility due to the lack of expansion. The thermal of the polymerization reaction is mainly regulated by the at least partial vaporization of the constituents of the non-polymeric phase of the reaction medium. The regulation of the thermal of the polymerization reaction by the vaporization of a part of the constituents of the non-polymeric phase of the reaction medium implies a free space (permanent or temporary) above said medium capable of accommodating the gas phase as has been defined previously. To control the temperature of the reactor and thus control the evacuation of the heat generated by the polymerization reaction, several configurations are possible. Thus, according to one variant, an internal condenser may be installed in the gas phase of the reactor. According to another variant, an external condensation loop is used. According to this variant, part of the gas phase generated by the vaporization of the reaction medium during the polymerization, is driven by an outlet of the reactor to a condenser. The condensate may then advantageously be re-injected in whole or in part into the reactor, partially replacing the solvent and / or isoprene in the isoprene / solvent mixture, or stored for later use. In the latter case, it is then necessary to readjust the flow into or out of the polymerization reactor so as to maintain constant reaction volume or residence time in the reactor.

A device may be installed to remove the non-condensables either from the reactor or from the condensation loop depending on the variants used to control the thermal of the reaction. According to another variant, the thermal of the polymerization reaction can also be partially controlled by the cooling provided by the initial components injected into the polymerization reactor when the temperature of said components is at a lower temperature than the reaction medium. The initial components injected into the polymerization reactor can thus be regulated at the desired temperature between -5 ° C. and room temperature.

According to other variants, the thermal of the polymerization reaction can also be partially controlled by the cooling via the double-envelopes or the stirring shafts of the reactors. These different variants are combinable with each other, while knowing that the process is continuous, the combined variants take place simultaneously. At least the variant of the external condensation loop will be preferred because the exchange surface is not limited by the space available inside the reactor. The polymerization is carried out in the reactor under conditions of thermodynamic equilibrium between the polymerization medium and the gas phase. Thus, according to a particular implementation of the process of the invention, a regulation of the pressure of the gas phase in the reactor, which is more reactive than a temperature regulation, can advantageously be put in place and make it possible to maintain the reaction medium at a pressure and therefore, due to the thermodynamic equilibrium, at a chosen temperature. According to an implementation of the method of the invention, the polymerization reaction can also be carried out under vacuum, in which case a connection to a vacuum circuit can preferably be provided on the external condensation loop. The very low values of absolute pressure allow polymerization at very low temperature, favorable operating conditions especially to the synthesis of high cis polyisoprene. Typically, the polymerization proceeds at a temperature in the range of -30 ° C to 100 ° C. The flexibility of the process advantageously makes it possible to work temperatures between 20 ° C and 60 ° C, which do not require large energetic contributions, without penalizing the productivity of the process.

During the polymerization stage of isoprene, the reaction medium, which can reach a high viscosity, is kept under stirring by the movement around a rotary axis, preferably a horizontal axis, of the agitator agitator (s) of the reactor. polymerization. Another step of the invention consists in continuously discharging a part of the reaction medium in the form of an elastomer paste comprising the synthesized pseudo-living polyisoprene. This continuous discharge is effected by a discharge device totally or partially integrated polymerization reactor, such as a gear or screw extraction device, disposed at the bottom or on the side of the reactor. To control the output flow of the reactor, the additional devices can be installed at the outlet of the reactor. Thus, according to a particular variant of the invention, the elastomer paste is discharged by the combined action of at least one drain screw and a gear pump, which are both the discharge system, by gavage gears with the elastomer paste discharged by the screw device. It is thus advantageously possible to maintain a flow rate leaving the reactor that is equivalent to a flow rate entering the reactor in order to ensure continuous operation with a constant residence time. When the discharge device comprises a screw, it can be single or double. According to another step of the process of the invention the solution of pseudo-living elastomer discharged in step d), is conveyed continuously (step e) to a mixer having a gas phase, at least one movable stirrer and a discharge device, to be functionalized (step g)) by a functionalization agent continuously introduced into said mixer (step f)). This mixer is advantageously self-cleaning. The term "self-cleaning" according to the invention, the fact that its stirring system sweeps at least 90% of the volume of the kneader, preferably 95% of the volume. Among the kneaders that can be envisaged, mention may be made of reactors of continuous kneading technology equipped with a device for discharging at least one screw, and in particular continuous mixers agitated with twin-screw discharge. Such kneaders are marketed, for example, by the company LIST AG under the name dual-arm kneader or "Twin Shaft Kneader Reactor" or by the company Buss-SMS-Canzler under the name of double-arm reactors or in english "large volume processors, twin horizontal shaft" According to the invention, in step (f), is continuously introduced into the kneader a functionalizing agent capable of reacting with a pseudo-living elastomer obtained at the end of polymerization by coordination catalysis.

The functionalization agent corresponds to the formula A-R1-B with A denoting a group capable of reacting on the reactive end of the pseudo-living elastomer, R1 denoting an atom or a group of atoms forming a bond between A and B and B denoting a function capable of reacting with a reinforcing filler; The R 1 group is preferably a linear, branched or cyclic divalent hydrocarbon radical, and may contain one or more aromatic radicals, and / or one or more heteroatoms. Said radical R1 may optionally be substituted, provided that the substituents are inert with respect to the reactive ends of the pseudo-living elastomer. According to preferred variants, the group R1 denotes a divalent aliphatic hydrocarbon radical C1-C18, saturated or unsaturated, cyclic or otherwise, which may contain one or more aromatic radicals According to variants of the invention, by group capable of reacting on the reactive end of the pseudo-living elastomer is understood to mean a group chosen from, in particular, epoxides, glycidyloxy, carbonyls, aldehydes, ketones, esters, carbonates, anhydrides, isocyanates, imines, alkoxysilanes, nitriles, aziridines, acyl chlorides, azines, cyclic halosilanes, oximes, ureas, methacrylates, hydrazones, lactones, thiolactones, thiocarboxylic acid esters, nitroso, carbamates. According to variants of the invention, by function capable of interacting with a reinforcing filler, is meant a functional group comprising one or more functions selected from a protected or non-protected primary amine, protected secondary or non-tertiary, an imine, an imide , amide, nitrile, azo, carbamate, methacrylate, methacrylamide, hydroxyl, carbonyl, carboxyl, epoxy, glycidyloxy, thiol, sulfide, disulfide, thiocarbonyl, thioester, sulfonyl, a silane, a silanol, an alkoxysilane, a di-alkoxysilane, a tri-alkoxysilane, a stannyl, a tin halide, a tin halide alkyl, a tin halide aryl, a polyether , a nitrogenous heterocycle, an oxygenated heterocycle, a sulfur heterocycle and an aromatic group substituted with the aforementioned groups. The various aspects, preferential or not, which precede and which concern in particular the nature of the group A, the group R1 and the function B, are combinable with one another. Thus, depending on the difficulties of synthesis and commercial availability, but especially as a function of the type of reinforcing filler envisaged in association with the modified elastomer, the skilled person will know which combinations, especially combinations of groups A and B cited above, are particularly advantageous. For example, it is possible, according to certain variants, to favor the groups glycydiloxy, epoxides, aldehydes, ketones, esters, alkoxysilanes, isocyanates, aziridines, acyl chlorides as a group capable of reacting on the reactive end of the pseudo-elastomer. living. For example, it is also possible to favor, according to certain variants, the function, imine, the primary amine functional group, protected or otherwise, secondary, protected or not, or tertiary, the mono, di or trialkoxysilane function, optionally substituted by a group comprising a amine function, as a function likely to interact with a reinforcing filler It is still possible to favor, according to certain variants, a C 1 -C 18 alkyl radical as a group forming a bond between A and B. As illustrations of these variants include functionalization agents such as (3-glycidyloxypropyl) methyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- (meth) acryloyloxypropyltrimethoxysilane, tris (3-triethoxysilylpropyl) isocyanurate, isocyanatopropyltriethoxysilane, (dioctyltin bis (2-ethylhexyl) maleate, 3-aminopropyltri thoxy silane, 3-mercaptopropyltriethoxysilane, 3-dimethylaminopropyl (triethoxy) silane, dibutyl bisbenzyl maleate tin, 4,4'-bis (diethylamino) benzophenone, N ', Ndimethylimidazolidinone, dichloronapthoquinone, diethylaminobenzaldehyde, 4,4'-diphenylmethane diisocyanate, polymethylenepolyphenylpolyisocyanate, 1,3-hexamethylene diisocyanate, 2,6-toluenediisocyanate, 1-butylaziridine, trimethylolpropane tris [3- (1-aziridinyl) propionate], butyrylaziridine, 2- (4 morpholinodithio) benzothiazole, N-oxydiethylene-2-benzothiazole sulfamamide, diethyldithiocarbamic acid 2-benzothiazoyl ester, N- (cyclohexylthio) phathalimide, dimethylcarbamic chloride, 4-morpholinecarbonylchloride. Among these functionalizing agents, (3-glycidyloxypropyl) methyldiethoxysilane is particularly advantageous. The functionalization step is carried out by reaction of at least one functionalization agent described above with the pseudo-living elastomer solution at a temperature in the range of -30 ° C to 100 ° C. According to certain advantageous variants, the functionalization may be carried out at temperatures between 40 ° C. and 70 ° C. The reaction time is at least 10 minutes.

The amount of functionalizing agent can vary over a wide range. According to variants of the invention, the molar ratio (functionalizing agent / total aluminum) is at least 1/1 and at most 10/1, preferably at most 5/1, or even at most 2/1. Total aluminum is the total amount of aluminum present in the reaction medium, taking into account the aluminum included in the alkylating agent and, if appropriate, the aluminum included in the additional alkylaluminium compound added in offset relative to to the catalytic system. According to one embodiment of the invention, the kneader may concomitantly with the functionalization, be used to concentrate the reaction medium by removing, if appropriate, a part of the solvent, and / or unreacted isoprene. A condensation loop is then used. This loop works in the same way as that of the polymerization reactor described above. The condensate stream may advantageously be reintroduced wholly or partly upstream of the first reactor, partly replacing the solvent and / or isoprene in the mixture of isoprene and solvent or stored for later use. According to another embodiment, the kneader may also, concomitantly with the functionalization, be used to devolatilize the reaction medium by optionally removing the solvent, and / or the unreacted isoprene. A condensation loop is then used. This loop works in the same way as that of the polymerization reactor described above. The condensate stream may advantageously be reintroduced wholly or partly upstream of the polymerization reactor, partly replacing the solvent and / or isoprene in the mixture of at least one monomer and solvent or stored for a second time. subsequent use. According to an advantageous embodiment of the invention, the kneader is dedicated to functionalization, without it being implemented concomitant concentration or devolatilization reaction. It is understood that, insofar as it is a continuous process, these different stages, when they are combined, are implemented simultaneously. The polyisoprene paste resulting from this functionalization step (step (g)) is continuously discharged from this kneader (step h). This continuous discharge is effected by a device which is provided with the mixer. Additional devices for transporting the products may be installed at the outlet of the reactor discharge device to control the output flow. Thus, according to a particular variant of the invention, the latter is discharged by the combined action of at least one drain screw and a gear pump which both constitute the discharge system, by feeding the gears with the functionalized polyisprene paste discharged by the screw device.

At this stage and according to a variant of the invention, the method for synthesizing a functionalized polyisoprene can be continued in a manner known per se. Thus, according to one embodiment, it is possible to inject a stopper and an antioxidant at this stage. The functionalized polyisoprene paste can then be routed to a device for cutting it. This type of device is preferably a granulator which makes it possible to transform the dough into particles of variable shapes and average volumes of between 0.07 cm3 and 12 cm3. The granulation step can be carried out under various conditions known to those skilled in the art and which are suitable for the process according to the invention. Thus, for example, the granulation can be carried out under water to feed a solvent removal step of the particles of the polyisoprene paste by stripping with water vapor, or in a gas phase to feed a step of removing the solvent from the functionalized polyisoprene pulp particles by drying different from the stripping with water. In a preferred aspect, the granulation will be carried out under water. . For example, this type of underwater granulator is marketed under various names such as underwater pelletizer, or in English "Underwater Pelletizers", marketed by Gala Industries, the underwater granulator, or in English "Underwater Pelletizing By Kreyenborg Industries. The process is then continued in a manner known per se by the separation and recovery of the prepared functionalized polyisoprene. The unreacted isoprene and / or the solvent contained in the elastomer paste, in particulate form, can be removed by methods known to those skilled in the art. The functionalized polyisoprene recovered at the end of these different steps can then be packaged in a manner known per se, in the form of bales, for example.

The method of the invention makes it possible to synthesize by continuous coordination catalysis a polyisoprene characterized by a molar ratio of cis of at least 95% relative to the elastomer, and by an average percentage of functionalized chains of at least 70%, up to 100%. This synthesis also offers the energy and environmental benefits of polymerization in highly concentrated media while ensuring increased productivity with a conversion rate of over 60%. The subject of the invention is also any installation intended for implementing the process of continuous synthesis of a functionalized polyisoprene and suitable for application on an industrial scale. By way of nonlimiting illustration, an installation for the continuous synthesis of a functionalized diene elastomer according to one embodiment of the synthesis method of the invention is more particularly described with reference to FIG. 1 constituting a schematic representation of a installation. Figure 1 is a diagram of an installation according to one embodiment of the invention for the continuous synthesis of a polyisoprene by light solvent coordination catalysis integrating a polymerization reactor, a self-cleaning mixer and a granulator.

The installation illustrated in FIG. 1 essentially comprises a polymerization reactor 1 which is provided with a gas phase and equipped with at least one stirring mobile, preferably with a double Z-arm, and with a discharge device at least one screw. In addition, the reactor 1 is characterized by a specific flow so that the residence time distribution function is such that the standard deviation of this function is greater than the average residence time divided by 2-V3, preferably greater than average residence time divided by 2. The polymerization reactor 1 is at least connected to a plurality of continuous supply sources including at least one feed source 2 in a catalytic system, a supply source 3 in isoprene at least, if appropriate mixed with the inert hydrocarbon solvent, and - at an outlet adapted to evacuate from said reactor 1, continuously, the pseudo-living polyisoprene paste into a flow leaving by a discharge device.

According to the variant of the installation illustrated in FIG. 1, the polymerization reactor 1 is connected to a supply source 3 in a mixture of isoprene and solvent. A mixer 4, situated upstream of the polymerization reactor 1, makes it possible to carry out this mixing. This mixer 4 is fed by an isoprene source 5 and a source of solvent 6, and is connected to the polymerization reactor 1. According to alternative embodiments of the catalytic polymerization process according to the invention, it is possible to introduce into the polymerization reactor, by a separate flow and independent of the introduction of the catalyst system used for the polymerization reaction, a predetermined additional amount of at least one alkylaluminium compound. According to an alternative installation illustrated by dotted lines in FIG. 1, the polymerization reactor 1 is also connected to an additional alkylating agent supply source 7. The alkylating agent may, alternatively, be added to the mixture of isoprene and solvent, before entering the reactor 1, the additional alkylating agent supply source 7 thus being connected to the isoprene and solvent supply source 3, as indicated in dotted line in FIG. 1 Alternatively, according to another alternative also illustrated in FIG. 1 by dotted lines, the alkylating agent can be injected directly into the mixer 4 to be mixed with the isoprene and the solvent, the additional alkylating agent supply source. 7 being then connected to the mixer 4. According to a variant of the installation illustrated in FIG. 1, the supply source of the catalytic system 2 can be connected to an installation non-illustrated for the continuous preparation of the catalyst system as described in EP 1 968 734 A1 The polymerization reactor 1 is provided with a discharge device with at least one screw which allows to continuously discharge the elastomer paste This discharge device consists of at least one emptying screw, integrated in the reactor 1, and a gear pump 10 downstream of the reactor 1. According to certain implementations of the polymerization process, the thermal of the polymerization reaction is regulated by the at least partial vaporization of the non-polymeric constituents of the reaction medium. In FIG. 1 illustrating a variant of this process, the polymerization reactor 1 is equipped with a condensation loop which allows the condensation of the gases coming from the reactor 1 via a condenser 8 and the return in all or part of the condensate in the reactor 1.

According to an optional embodiment not illustrated, the condensation loop may advantageously be connected to a device for the elimination of incondensable products in a manner known per se. The plant also comprises a kneader 11 downstream of the polymerization reactor 1 and connected thereto via the gear pump 10. The kneader 11 has a stirring device which sweeps at least 90% of the volume of the kneader, preferably 95% of its volume, thus ensuring a self-cleaning. The kneader 11 is at least provided with an inlet connected to a supply source of pseudo-living polyisoprene paste discharged from the polymerization reactor 1 by the gear pump 10, an input connected to a source of supplying functionalization agent 12 - an outlet adapted to discharge said mixer 11, continuously, the functionalized polyisoprene pulp into a flow 13 to the pump 16. The mixer 11 is provided with a discharge device at least a screw which continuously discharges the functionalized polyisoprene paste into an outflow 13. This discharge device consists of at least one emptying screw, integrated into the mixer 11 and a gear pump 16 located downstream of the Mixer 11. The flow of functionalized polyisoprene paste 13 is conveyed to the granulator 17, preferably under water, to be cut through the gear pump 16 which is connected to the granulator. According to the implementation of the polymerization process illustrated in FIG. 1, the mixer 11 is exclusively dedicated to functionalization. According to alternative arrangements of other implementations of the process, not illustrated in FIG. 1, the mixer 11 may be equipped with a condensation loop which allows the condensation of the gases coming from the reactor 11 via a condenser and the return all or part of the condensate in the polymerization reactor 1. According to one embodiment of these non-illustrated variants, the condensation loop can advantageously be connected to a device for the elimination of incondensable products in a manner known per se.

According to the embodiment of the invention illustrated in FIG. 1, the flow of the functionalized polyisoprene paste 13 discharged from the kneader 11, a stopper and an antioxidant, is then injected respectively through feed sources 14 and 15. upstream of the gear pump 16.

The installation illustrated in Figure 1 further comprises a cutting device 17, for example a granulator preferably under water. The cutting device 17 is provided with an inlet connected to the gear pump 16 through which the discharge device supplies the device 17 in polyisoprene paste to be cut. The device 17 is also provided with an outlet adapted to evacuate from said device 17, continuously, the polyisoprene paste particles functionalized in a stream 18, to include a device for the removal of solvent and isoprene. A - METHODS OF MEASUREMENT I - Determination of the microstructure of the polyisoprenes obtained.

The so-called "near infrared" (NIR) assay technique was used. This is an indirect method using "control" elastomers whose microstructure has been measured by the 13C NMR technique. The quantitative relationship (BeerLambert's law) existing between the distribution of the monomers in an elastomer and the shape of the NIR spectrum thereof is used. This technique is implemented in two steps: 1) Calibration: - The respective spectra of the "control" elastomers are acquired. - A mathematical model associating a microstructure with a given spectrum is established using the Partial Least Squares (PLS) regression method based on a factorial analysis of the spectral data. The following two papers deal extensively with the theory and implementation of this "multi-varied" data analysis method: (1) P. GELADI and BR KOWALSKI "Partial Least Squares regression: a tutorial Analytica Chimica Acta, vol. 185, 1-17 (1986). (2) M. TENENHAUS "The regression PLS - Theory and practice" Paris, Editions Technip (1998). 2) Measurement: - A recording of the spectrum of the sample is carried out. - The calculation of the microstructure is carried out. II - Determination of the amount of GlVIDE grafted to the polvisoprenes obtained. a) Principle: This determination is carried out by NMR analysis on coagulated samples. The spectra are acquired on a BRUKER 500 MHz Avance spectrometer equipped with a BBIz-grad 5 mm wideband probe.

The quantitative 1H NMR experiment uses a 30 ° single-pulse sequence and a 5-second repetition time between each acquisition (1024 acquisitions). b) Sample preparation: The samples, approximately 25 mg, are solubilized in carbon disulfide (CS2), approximately 1 ml. 100 μL of deuterated cyclohexane (C6D12) is added for the lock signal. c) Characterization: The 1 H NMR spectrum makes it possible to quantify the ethylenic units of the IR by integration of the signal masses characteristic of the following protons: P1 1-4: 1H ethylenic 8ppm 1H massive between 5.40ppm and 4.75ppm PI3-4: 2H ethylene 8ppm 1H solid between 4.75ppm and 4.30ppm The chemical shifts are calibrated with respect to the protonated impurity of CS2 8ppm 1H at 7.18ppm referenced on the TMS (ppm 1H at Oppm).

The 1H NMR spectrum makes it possible to quantify the GMDE units grafted by integrations of the massifs of signals characteristic of the protons according to: CH2-0-Si-: 8ppm 1H massive at 3.6ppm -CH2-0- + -CH-O-: 8ppm 1H massive at 3.25ppm -CH2-0-: 8ppm 1H solid at 3.00ppm CE13-Si-: 8ppm 1H solid at -0.02ppm CH2-Si-: 8ppm 1H massive at 0.46ppm The chemical shifts are calibrated with respect to the protonated impurity from CS2 8ppm 1H to 7.18ppm referenced on the TMS (ppm 1H at Oppm).

The 2D NMR correlation spectrum 1H / 13C 1J HSQC edited makes it possible to verify the nature of the grafted pattern by virtue of the chemical shifts of the carbon and proton atoms.

III - Determination of the molecular weight distribution of polyisoprenes obtained by the steric exclusion chromatography (SEC) technique. a) Principle of the measurement Size exclusion chromatography (SEC) is used to separate the macromolecules in solution according to their size through columns filled with a porous gel. The macromolecules are separated according to their hydrodynamic volume, the larger ones being eluted first.

Without being an absolute method, the SEC allows to apprehend the distribution of the molar masses of a polymer. From commercial standard products, the various average molar masses (Mn) and weight (Mw) can be determined and the polymolecularity index (Ip = Mw / Mn) calculated via a so-called calibration of MOORE. b) Preparation of the polymer: There is no particular treatment of the polymer sample before analysis. This is simply solubilized in tetrahydrofuran at a concentration of about 1 g / l. c) SEC analysis: Case cl) The equipment used is a "WATERS alliance" chromatographic chain. The elution solvent is tetrahydrofuran, the flow rate is 1 ml / min, the temperature of the system is 35 ° C and the analysis time is 30 min. A set of two WATERS columns with the trade name "STYRAGEL HT6E" is used. The injected volume of the solution of the polymer sample is 100 μl. The detector is a differential refractometer "WATERS 2140" and the chromatographic data exploitation software is the "WATERS MILLENNIUM" system.

Case c2) The apparatus used is a "WATERS alliance" chromatograph. The elution solvent is tetrahydrofuran, the flow rate 0.7 ml / min, the system temperature 35 ° C and the analysis time 90 min. A set of four WATERS columns in series, trade names "STYRAGEL EIMW7", "STYRAGEL HMW6E" and two "STYRAGEL HT6E" are used. The injected volume of the solution of the polymer sample is 100 μl. The detector is a "WATERS model RI32X" differential refractometer and the chromatographic data exploitation software is the "WATERS 10 MILLENNIUM" system. B - TESTS 15 Synthesis processes of a polyisoprene functionalized by coordination catalysis in a highly concentrated medium according to a variant of the invention Some definitions: Nd = neodymium Bd = butadiene Isop = isoprene MCH = methylcyclohexane HDiBA = diisobutylaluminum hydride TOA = trioctylaluminum CDEA = diethylaluminum chloride TiBA = triisobutylaluminum GMDE = (3-glycidyloxypropyl) methyldiethoxysilane I - Synthesis of Catalytic Systems 1- Nd / Bd / HDiBA / CDEA The Nd / Bd / HDiBA / CDEA catalytic system diluted in MCH is synthesized according to the procedure described in WO-A-02/38636 in the name of the Applicants: In order to obtain this catalyst, the neodymium phosphate salt in powder form is introduced into a reactor previously cleaned of its impurities . This salt is then sparged with nitrogen for 10 min in order to render the reaction medium inert. The following successive steps are then carried out: First solvation step: A solvent consisting of previously distilled MCH, purified on alumina and bubbled with nitrogen is introduced into the reactor. In order to form a gel, the duration and the temperature of contacting this solvent with the neodymium salt are 30 minutes at 30 ° C. with stirring. Second stage of addition of the monomer: The butadiene previously purified on alumina and sparged with nitrogen is then introduced into the reactor at 30 ° C. This monomer will be used to preform the catalyst during the aging step. Third alkylation step: The HDiBA in solution in the MCH is then introduced into the reactor as agent for alkylation of the neodymium salt, at a concentration of about 1 mol / L. The duration of the alkylation is 15 min. The temperature of the alkylation reaction is equal to 30 ° C. - Fourth halogenation step: The CDEA in solution in the MCH is then introduced into the reactor as a halogen donor, in a concentration of approximately 0.degree. , 5 mol / L. The temperature of the reaction medium is brought to 60 ° C. - Fifth aging step: The mixture thus obtained is aged while maintaining the temperature of 60 ° C. for a period of 50 minutes. The catalytic solution obtained is finally stored under a nitrogen atmosphere at a temperature between -15 ° C. and -5 ° C. The catalytic system is characterized by its catalytic formula which is given in the form of Nd / Monomer / Alkylating Agent. Halogenating agent in molar ratios indexed on neodymium salt. In the examples, the neodymium concentration is 0.02 mol / L. 2- Ndilsop / T0A / CDEA The Nd / Isop / TOA / CDEA catalytic system is diluted in n-pentane. In order to obtain this catalyst, the powdered neodymium phosphate salt is introduced into a reactor previously cleaned of its impurities. This salt is then sparged with nitrogen for 10 min in order to render the reaction medium inert. The following successive steps are then carried out: First solvation step: A solvent consisting of n-pentane previously purified on alumina and bubbled with nitrogen is introduced into the reactor. In order to form a gel, the duration and the temperature of contacting this solvent with the neodymium salt are 30 minutes at 30 ° C. with stirring. Second Stage of Addition of the Monomer: The isoprene previously purified on alumina and sparged with nitrogen is then introduced into the reactor at 30 ° C. This monomer will be used to preform the catalyst during the aging step. Third alkylation step: The TOA in solution in n-pentane is then introduced into the reactor as agent for alkylating the neodymium salt, at a concentration of approximately 1 mol / l. The duration of the alkylation is 15 min. The temperature of the alkylation reaction is equal to 30 ° C. Fourth halogenation step: The CDEA in solution in n-pentane is then introduced into the reactor as a halogen donor, in a concentration of about 0.5 mol / L. The temperature of the reaction medium is brought to 60 ° C. - Fifth aging step: The mixture thus obtained is aged while maintaining the temperature of 60 ° C. for a period of 50 minutes. The catalytic solution obtained is finally stored under a nitrogen atmosphere at a temperature of between -15 ° C. and -5 ° C.

The catalytic systems are characterized by their catalytic formula which is given in the form of Nd / Monomer / Alkylating Agent / Halogenating Agent in molar ratios indexed on the neodymium salt. In the examples, their neodymium concentration is 0.02 mol / L.

II-Procedure followed for the continuous polymerizations Example 1 The continuous polymerization is carried out on a line comprising a reactor with a double Z-arm gas phase of 150 liters total, equipped with a discharge device with a drain screw and a gear pump and a self-cleaning mixer, also equipped with a discharge device with a drain screw and a gear pump. This continuous line corresponds to the installation shown in FIG. 1. Isoprene and pentane are mixed in a dynamic mixer 4 provided for this purpose upstream of the polymerization reactor 1. The mixture obtained is injected in the form of a flow entering 3 directly into the reactor 1. The isoprene is injected with a flow rate of 7.8 kg / h according to a flow 5 in the mixer 4. The pentane is injected with a flow rate of 12.54 kg / h according to a flow 6 in the mixer 4, ie about 37% by weight of monomer in the reaction medium.

A catalytic coordination system is also injected directly into the reactor 1 in a flow 2. It was prepared following the method of preparation described in paragraph I above, part 2. The catalytic system has the following molar ratios with respect to neodymium: Nd / isoprene / TOA / CDEA = 1/30/8 / 2.8 The amount of neodymium is 150moles per 100g of isoprene to be polymerized. The molar concentration of neodymium in the catalyst is 0.02 mol / l. TiBa is also injected directly into the reactor 1 in a separate and independent stream 7, as an additional alkylaluminium compound. The amount of TiBa injected is 680 i.tmoles / 100g of isoprene. The molar concentration of the TiBa solution is 0.1 mol / L. The pressure of the gas phase is regulated to 0.5 barg, the vapors are condensed in an external condenser 8 and returned to the Z-twin-arm polymerization reactor 1. The temperature of the jacket is maintained at 60 ° C. The average residence time of the reaction is 80 minutes. The discharge screw makes it possible to transfer the product of the reactor 1 to a gear pump 10.

No expansion phenomenon is observed. The conversion measured on a sample taken at the limit of the first third of the reactor volume is 91%. The conversion measure was derived from a GPC measurement of isoprene in the sample taken. Residual isoprene, in the sample taken, was assayed at 3.4% by mass. The flows are characterized by the residence time distribution given in FIG. 2. The experimental points for establishing this residence time distribution were obtained by measuring, by Gas Chromatography, the evolutions in the concentration of a tracer following a very fast injection according to a mode of impulse introduction of a chemically inert product according to the principle described in the book Jacques Villermaux, Chemical reaction engineering: design and operation of reactors. Editors. 1993, TEC & DOC - LAVOISIER, Page 170 to 172. The experimental points are taken from samples taken in the stream 9 of Figure 1 at the outlet of the reactor 1, at the end of the discharge screw. The modeling of these experimental points by a gamma law made it possible to determine the variance of the residence time distribution function E.

The gamma law for modeling the residence time distribution function E is as follows: E- - t tk - 1 * and f (k) tok With: T (k): gamma function of k; k: 1.22; t0: average residence time, 80 minutes; t: residence time; The variance of this residence time distribution function is equal to k *. The standard deviation of the residence time distribution function which is equal to 80 88.4 is deduced, which is greater than the average residence time. divided by 2-V3, ie 2,. / 3 2, 23.1. The discharge screw is used to transfer the product from the reactor 1 to a gear pump 10.

The gear pump 10 transfers the pseudo-living elastomer paste to a self-cleaning mixer with gas phase 11. The flow rate transferred by the gear pump 10 is equal to the sum of the flow rates injected into the reactor 1. The self-cleaning mixer is a 39-liter total volume double-arm kneader-mixer with a discharge device consisting of a twin-screw drain and a gear pump 16. The flow in this double-arm kneader-mixer can be likened to a piston flow. The temperature of the jacket is maintained at 68 ° C. The average residence time of the functionalization reaction with the pseudo-living polymer solution in the self-cleaning mixer 11 is 37 minutes.

The GMDE is injected with a flow rate of 0.456 l / h in the self-cleaning mixer at the same level as the arrival of the solution in the mixer. The GMDE solution is concentrated at 0. 47 mol / L. The flux stopper 14 and the antioxidant stream used are acetyl acetone, with a flow rate of 0.224 l / h at a concentration of 120 g / l, and N-1,3-dimethylbutyl-N'-phenyl-para-phenylenediamine. at 0.5 μcm (mw: parts by weight per 100 parts by weight of monomer-isoprene). This stopper and this antioxidant are injected upstream of the gear pump 16; The gear pump 16 transfers the elastomer paste to the underwater granulator 17. The flow rate transferred by the gear pump 16 is equal to the sum of the flow rates injected into the reactor 1, to which is added the flow rates of the functionalizing streams. of stopper 14 and antioxidant 15. The degree of functionalization obtained is 70%.

EXAMPLE 2 The continuous polymerization is carried out on a line comprising a reactor with a double Z-arm gas phase of 150 liters total, equipped with a discharge device with a drain screw and a gear pump and a self-cleaning mixer, also equipped with a discharge device with a drain screw and a gear pump. This continuous line corresponds to the installation shown in FIG. 1. Isoprene and pentane are mixed in a dynamic mixer 4 provided for this purpose upstream of the polymerization reactor 1. The mixture obtained is injected in the form of a flow entering 3 directly into the reactor 1. The isoprene is injected with a flow rate of 7.52 kg / h according to a flow 5 in the mixer 4. The pentane is injected with a flow rate of 12.01 kg / h according to a flow 6 in the mixer 4, ie about 37% by weight of monomer in the reaction medium.

A catalytic coordination system is also injected directly into the reactor 1 in a stream 2. The catalyst system is based on tris [bis- (2-ethylhexyl) phosphate] neodymium, isoprene as pre-forming monomer, TOA as an alkylating agent and CDEA as a halogen donor. It was prepared following the method of preparation described in the previous paragraph, part 2. The catalytic system has the following molar ratios with respect to neodymium: Nd / isoprene / TOA / CDEA = 1/30/8 / 2.8 The amount neodymium is 170moles per 100g of isoprene to be polymerized. The molar concentration of neodymium in the catalyst is 0.02 mol / l.

TiBa is also injected directly into reactor 1 in a separate and independent stream 7 as an additional alkylaluminum compound. The amount of TiBa injected is 2200 amoles / 100 g of isoprene to be polymerized. The molar concentration of the TiBa solution is 0.294 mol / L.

The pressure of the gas phase is regulated at 0.16 barg, the vapors are condensed in an external condenser 8 and returned to the polymerization reactor 1 with a double Z-arm. The temperature of the jacket is maintained at 21 ° C.

The average residence time of the reaction is 80 minutes. The discharge screw makes it possible to transfer the product of the reactor 1 to a gear pump 10.

No expansion phenomenon is observed. The conversion measured on a sample taken at the limit of the first third of the reactor volume is 92%. The conversion measure was derived from a GPC measurement of isoprene in the sample taken. Residual isoprene, in the sample taken, was assayed at 2.9% by mass. The flows are characterized by the residence time distribution given in FIG.

The experimental points allowing to establish this distribution of residence time were obtained by measuring by Gas Chromatography the evolutions of concentration of a tracer following a very fast injection according to a mode of impulse introduction of a chemically inert product. according to the principle described in the book Jacques Villermaux, Chemical reaction engineering: design and operation of reactors. Editors. 1993, TEC & DOC - LAVOISIER, Page 170 to 172. The experimental points are taken from samples taken in the stream 9 of Figure 1 at the outlet of the reactor 1, at the end of the discharge screw. The modeling of these experimental points by a gamma law made it possible to determine the variance of the residence time distribution function E. The gamma law for modeling the residence time distribution function E is as follows: E- - t tk - 1 * et0 F (k) tok With: T (k): gamma function of k; k: 1.22; t0: average residence time, 80 minutes; t: residence time; The variance of this residence time distribution function is equal to k * t. The standard deviation of the residence time distribution function which is equal to 80 88.4 is deduced, which is greater than the residence time. average divided by 2-V3, ie 2,. / 3 2, fi 23.1. The discharge screw makes it possible to transfer the product of the reactor 1 to a gear pump 10.

The gear pump 10 transfers the pseudo-living elastomer paste to a self-cleaning mixer with gas phase 11. The flow rate transferred by the gear pump 10 is equal to the sum of the flow rates injected into the reactor 1. The self-cleaning mixer is a 39-liter total volume double-arm kneader-mixer with a discharge device consisting of a twin-screw drain and a gear pump 16. The flow in this double-arm kneader-mixer can be likened to a piston flow. The temperature of the jacket is maintained at 68 ° C. The average residence time of the functionalization reaction with the pseudo-living polymer solution in the self-cleaning mixer 11 is 37 minutes.

The GMDE is injected with a flow rate of 0824 l / h into the self-cleaning mixer at the same level as the arrival of the solution in the mixer. The GMDE solution is concentrated at 0. 45 mol / L. The flux stopper 14 and the antioxidant stream used are acetyl acetone, with a flow rate of 0.387 l / h at a concentration of 120 g / L, and N-1,3-dimethylbutyl-N'-phenyl-para-phenylenediamine. at 0.5 μcm (mw: parts by weight per 100 parts by weight of monomer-isoprene). This stopper and this antioxidant are injected upstream of the gear pump 6. The gear pump 16 transfers the elastomer paste to the underwater granulator 17. The flow rate transferred by the gear pump 16 is equal to the sum of the flow rates injected into the reactor 1, to which are added the flow rates of the functionalizer 12 and the antioxidant 15 and the functionalizing agent. The functionalization ratio obtained is 100%. A non-functional polyisoprene was synthesized according to the method described in FIG. Example 1 using a catalyst system having the following molar ratios with respect to neodymium: Nd / isoprene / TOA / CDEA = 1/30/8 / 2.8, with the difference that no functionalizing agent was introduced into the mixer 11. The amount of neodymium is 100 amoles per 100 g of isoprene to be polymerized. The molar concentration of neodymium in the catalyst is 0.02 mol / l. TiBa is also injected directly into the reactor 1 in a separate and independent stream 7 as an additional alkylaluminum compound. The amount of TiBa injected is 900 μmol / 100 g of isoprene. The molar concentration of the TiBa solution is 0.1 mol / L. For all previous polymerizations, the conversion measured on a sample taken from the stream 9 upstream of the gear pump 10 is 99% at 80 min of overall reaction time. The conversion measure was derived from a GPC measurement of isoprene in the sample taken. Tables 1 and 2 show the polymerization tests carried out with both types of catalyst system and the associated functional polyisoprenes. Table 1: Control Catalytic Form Nd / Is Op / TOA / CDEA Stoichiometry 1/30/8 / 2.8 Concentration Nd (pmcm) 100 Transfer Agent TiBA Concentration Transfer Agent (pmcm) 900 Pressure Reactor Gas (Barg) 0.50 Mn / Ip (g.mo1-1 / -) Cis (`) / 0) 428500 / 2.25 95.1 Table 2: Examples 1 2 Nd / lsop / T0A / CDEA catalytic formula Nd / l50p / T0A / CDEA Stoichiometry 1/30/8 /2.8 1/30/8 / 2.8 Nd concentration (pmcm) 150 170 TiBA transfer agent TiBA Tranferrate transfer agent concentration (pmcm) 680 2200 Reactor gas phase pressure (Barg) 0.50 0.16 GMDE / AI total 1.2 1.2 Mn / lp (g.mor1 / -) 440000 / 2.28 436200 / 2.46 CH2-Si / PI NMR 1H (meq / kg) 1.6 2.3 ° With medium functionalized chains (° / 0) 70 100 Cis (° / 0) 95.7 97.7 The average percentage functionalized chain (in%) is obtained by the formula: (CH2-Si / P1) * Mn * 1.104 with CH2-Si / PI in meq / kg and Mn in g.mo14.

This method for synthesizing polyisoprene according to the invention, in a very concentrated and continuous medium, makes it possible to achieve a high conversion rate of 99%, of which at least 91% is at the limit of the first third of the reaction volume of the polymerization reactor 1 In addition, the standard deviation of the residence time distribution function in the polymerization reactor is greater than the average residence time divided by 2-V3. The average functionalization rate (or average percentage of functionalized chains) is also high since it varies from 70% to 100% of functionalized chains. This process is perfectly flexible and adaptable to economically attractive industrial production due to the reduced amount of solvent used while ensuring increased productivity with a high conversion rate.

Evaluation of the Polyisoprenes Prepared in the Rubber Composition 1-Manufacture of the Rubber Compositions: All the necessary basic constituents (diene elastomer, reinforcing filler and coupling agent, plasticizer, other additives) are successively introduced into a conventional internal mixer. the exception of the crosslinking system. Thermomechanical work (non-productive phase) is then carried out in one step, which lasts a total of about 3 to 4 minutes, until a maximum temperature of "fall" of 165 ° C is reached. The mixture thus obtained is recovered and cooled. After cooling the mixture thus obtained, is then incorporated in an external mixer (homo-finisher) maintained at low temperature, the crosslinking system composed of sulfur and a sulfenamide (CBS). The whole is then mixed (productive phase) for a few minutes (about ten minutes).

The final composition thus obtained is then calendered in the form of a sheet or a plate for a characterization in the laboratory. The vulcanization (or cooking) is conducted in a known manner at a temperature generally between 130 ° C and 200 ° C, for a sufficient time which may vary for example between 5 and 90 min depending in particular on the cooking temperature. 2- Measurements and Tests: The rubber compositions are characterized after cooking as indicated below. Dynamic properties are measured on a viscoanalyzer (Metravib VA4000) according to ASTM D 5992-96. The response of a sample of vulcanized composition (cylindrical specimen 4 mm in thickness and 400 mm 2 in section), subjected to a sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, is recorded during a scanning. temperature, under a fixed stress of 0.7 MPa, the observed tan value is recorded at -10 ° C (ie tan () - 10 ° C). The same sample is also subjected, at a temperature of 40 ° C. or 60 ° C., to a strain amplitude sweep from 0.1% to 50% (forward cycle), then from 50% to 1% (return cycle). : for the return cycle, the maximum value of the loss factor is recorded, denoted tan () max. The non-linearity denoted AG * is the difference in shear modulus between 0.1% to 50% deformation in MPa. It will be recalled that, in a manner well known to those skilled in the art, the value of tan () max (according to a "deformation" sweep at a given temperature) is representative of the hysteresis and the rolling resistance (plus tan). () max is low, hysteresis is the lowest and therefore the rolling resistance) while the value of tan () - 10 ° C (according to a "temperature" sweep, given deformation) is representative of the potential of adhesion to wet (more tan () - 10 ° C is high, better adhesion). 3 - Results The compositions and their properties are reported in Tables 3 and 4 below. TABLE 3 COMPOSITION A EXAMPLE 1 100 EXAMPLE 2 100 Control 100 N234 6 6 6 Zeosil Silica 1165MP Rhodia 80 80 80 Coupling Agent TESPT (5i69 Degussa) 6.4 6.4 6.4 PLASTICIZER A 10 10 PLASTICIZER B 25 25 25 Ozone wax C325T 1.5 1.5 1.5 Antiozonant (6PPD) 1.9 1.9 1.9 Diphenylguanidine (DPG) 1.5 1.5 1.5 ZnO 2 2 2 Stearic acid 2 2 2 Sulfur 1.2 1.2 1.2 CBS 1.8 1.8 1.8 Plasticizer A TDAE Oil Plasticizer B - polylimonene resin "Dercolyte L120" from DRT Table 4 Composition A tan (6) nnax (40 ° C 10Hz) 0.261 0.249 0.293 DG * (40 ° C 10Hz) 3.44 3.04 4.17 tan (6) -10 ° C (0.7 MPa 10Hz) 0.71 0.7 0.72 The properties at The vulcanized state of the compositions shows that the compositions according to the invention (compositions A and B) have hysteresis properties as well as strongly improved reinforcing and breaking properties compared to those of the reference composition. implementing a non-functionalized IR (com position C), which is very favorable to obtain a tire with a reduced rolling resistance when the composition according to the invention is used either as a tread, or as a tread underlayer or as a flank gum. When the composition according to the invention is used as a tread, wet grip performance is further retained (values of tan (8) -10 ° C near).

APPENDIX 1 The inherent viscosity is determined by measuring the flow time (t) of the polymer solution and the toluene flow time (to) in a capillary tube. In a tube Ubbelhode (diameter of the capillary 0.46 mm, capacity 18 to 22 ml), placed in a bath thermostated at 25 ± 0.1 ° C, the flow time of toluene and that of the polymer solution (C) at 0 , 1 g / d1 are measured. The inherent viscosity is obtained by the following relationship: ## EQU1 ## with: C: concentration of the toluene solution of polymer in g / dl; t: flow time of the toluene solution of polymer in seconds; to: toluene flow time in seconds; thnh: inherent viscosity expressed in dl / g.15

Claims (23)

REVENDICATIONS1. Process for the continuous synthesis of a functionalized polyisoprene, characterized in that it comprises the following simultaneous stages, related to the polymerization: a) continuous introduction into a polymerization reactor equipped with a gas phase and equipped with least one stirring motive and a discharge device, at least i. an isoprene-based catalyst system, as a preforming monomer, a rare earth metal salt of an organic phosphoric acid, or a rare earth metal salt of a carboxylic acid; a saturated or unsaturated inert hydrocarbon solvent whose boiling point is less than 40 ° C. at atmospheric pressure; an alkylating agent consisting of a trialkylaluminium of formula A1R3, in which R represents an alkyl radical preferably having from 1 to 10 carbon atoms, preferably trioctylaluminium; and - a halogen donor consisting of an alkylaluminum halide, the alkyl radical preferably having from 1 to 8 atoms; ii. isoprene as a monomer to be polymerized, and iii. from 0% to 70% by weight of a polymerization solvent, calculated with respect to the total mass of isoprene to be polymerized and solvent; b) continuously polymerize the isoprene, using the means necessary to achieve a conversion of at least 60% at the limit of the first third of the reaction volume of the polymerization reactor; c) stirring the polymerization medium by the continuous movement of at least one stirring member around a rotary axis; d) continuously discharging the pseudo-living polyisoprene paste resulting from the polymerization; the standard deviation of the residence time distribution function in the polymerization reactor being greater than the average residence time divided by 2 \ i3; - related to functionalization: e) continuously convey this paste to a mixer having a gas phase, a stirring device to at least one stirring device and a discharge device; continuous in the kneader a functionalizing agent corresponding to the formula A-R1-B with A denoting a group capable of reacting on the reactive end of the pseudo-living polyisoprene, R1 denoting a divalent aliphatic hydrocarbon radical, saturated or unsaturated, cyclic or no, C1-C18, aromatic C6-C18, and B denoting a function capable of reacting with a reinforcing filler g) continuously functionalize the pseudo-living polyisoprene by reaction with the functionalizing agent in said kneader; h) continuously discharging the functionalized polyisoprene paste from the previous step; i) recovering the functionalized polyisoprene. 2. Process according to claim 1, characterized in that the degree of conversion is at least 80%, in limit of the first third of the reaction volume of the polymerization reactor. 3. Method according to claim 1 or 2, characterized in that the standard deviation of the residence time distribution function within the polymerization reactor is greater than the average residence time divided by 2. 4. Method according to any one of the preceding claims, characterized in that the stirring of the polymerization medium is effected by the continuous movement of two stirring wheels. 5. Method according to claim 4, characterized in that the blades are sigma or Z type blades. 6. Method according to any one of the preceding claims, characterized in that in step h), the functionalized polyisoprene pulp discharged is conveyed to a granulator for cutting said functionalized polyisoprene paste. 7. Method according to claim 6, characterized in that the granulator is a granulator under water. 8. Method according to any one of the preceding claims, characterized in that the agitation device of the kneader scans at least 90% of the volume of the kneader, preferably 95% by ensuring a self-cleaning. 9. Method according to any one of the preceding claims, characterized in that the discharge of the polyisoprene paste in step d) and in step h) is carried out by the combined action of at least one screw drain and a gear pump which constitutes the discharge device. 10. Process according to any one of the preceding claims, characterized in that the R1 group is a divalent hydrocarbon radical, linear, branched or cyclic, and may contain one or more aromatic radicals, and / or one or more heteroatoms, preferably a divalent aliphatic hydrocarbon radical C1-C18, saturated or unsaturated, cyclic or otherwise, which may contain one or more aromatic radicals. Process according to any one of the preceding claims, characterized in that the group A capable of reacting on the reactive end of the pseudo-living polyisoprene is chosen from epoxides, glycidyloxy, carbonyls, aldehydes, ketones, esters, carbonates, anhydrides, isocyanates, imines, alkoxysilanes, nitriles, aziridines, acyl chlorides, azines, cyclic halosilanes, oximes, ureas, methacrylates, hydrazones, lactones thiolactones, thiocarboxylic acid esters, nitroso, carbamates. 12. Method according to any one of the preceding claims, characterized in that the function capable of interacting with a reinforcing filler is a functional group comprising one or more functions chosen from a protected or non-protected primary amine, secondary protected or non-tertiary , imine, imide, amide, nitrile, azo, carbamate, methacrylate, methacrylamide, hydroxyl, carbonyl, carboxyl, epoxy, glycidyloxy, thiol, sulfide, disulfide, thiocarbonyl, thioester, sulfonyl, silane, silanol, alkoxysilane, di-alkoxysilane, trialkoxysilane, stannyl, tin halide, tin halide alkyl, halide aryl tin, a polyether, a nitrogenous heterocycle, an oxygenated heterocycle, a sulfur heterocycle and an aromatic group substituted with the aforementioned groups. 13. Method according to any one of the preceding claims, characterized in that the catalytic system satisfies at least one of the following characteristics, preferably all: - the rare earth salt (s) is a neodymium organophosphate , preferably tris [bis (2-ethylhexyl) phosphate] neodymium; the inert hydrocarbon solvent is an alkane, preferentially n-pentane, the alkylating agent is trioctylaluminum; and, the halogen donor is an alkylaluminium halide, preferably diethylaluminum chloride. 14. Method according to any one of the preceding claims, characterized in that during step a), is introduced continuously into the polymerization reactor, with a flow different from that of the catalyst system, at least one alkyl aluminum compound of formula A1R3 or HA1R2 in which R represents an alkyl radical and H a hydrogen atom. 15. Process according to claim 14, characterized in that prior to step a), the alkylaluminium compound, the polymerization solvent and the isoprene to be polymerized are brought into contact to form a mixture which is introduced into the polymerization reactor. during step a). 16. Process according to any one of the preceding claims, characterized in that the polymerization solvent is identical to the solvent of the catalytic system, and is an alkane, preferably pentane. 17. Installation for the implementation of a method according to one of the preceding claims, characterized in that it comprises - a polymerization reactor (1) provided with a gas phase and equipped with at least one stirring mobile and a discharge device, the reactor (1) being at least provided with: - several inputs connected respectively to several power sources including at least one power source (2) in a catalytic system, a power source (5) isoprene and, where appropriate, a feed source (6) inert hydrocarbon solvent, and - an outlet adapted to evacuate from said reactor (1), continuously, the polyisoprene paste pseudo-living in an outgoing flow connected via a discharge device to a self-cleaning type mixer (11) - a stirring device adapted to the high viscosities of the reaction medium, - a discharge device consisting of minus one drain screw; - A kneader (11), preferably of the self-cleaning type sweeping at least 90% of the volume of the kneader, as a functionalization reactor, at least provided with an inlet connected to a supply source of polyisoprene paste pseudo-living (9) discharged from the polymerization reactor (1), - an inlet connected to a supply source (12) functionalizing agent, and- an outlet adapted to evacuate said mixer (11), continuously, the functionalized polyisoprene paste in an outflow (13) to the device (17) for cutting the polyisoprene paste. 18. Installation according to claim 17, characterized in that the polymerization reactor (1) is a double-sigma or Z-shaped reactor. 19. Installation according to claim 17 or 18, characterized in that the device (17) for cutting the polyisoprene paste discharged from the mixer (11) is a granulator. 20. Installation according to any one of claims 17 to 19, characterized in that the discharge device of the polymerization reactor (1) and / or the kneader (11), consists of at least one drain screw to the end of which is connected a gear pump (10) and / or (16). 21. Installation according to any one of claims 17 to 20, characterized in that it comprises a supply source (7) of an alkylaluminium directly connected to the polymerization reactor (1) or connected to the mixture of flows (6). and (5) upstream of the polymerization reactor provided that the supply of the catalyst system (2) is independent of this flow mixture. 22. Installation according to any one of claims 17 to 21, characterized in that at least one of the reactor (1) and the mixer (11) is provided with a second outlet to a condenser. 23. Installation according to claim 22, characterized in that at least one of the condensers is provided with an outlet for returning the condensate to the reactor (1).