PROCESS FOR TERMINATING POLYMERS THROUGH COAGULATION The invention relates to a process for the termination by coagulation of polymers. More particularly, the invention relates to a refinement of the vapor coagulation process, the termination of block and arbitrary copolymers which are predominantly derived from conjugated diene and / or predominantly from aromatic monovinyl. The use of steam coagulation processes to finish arbitrary and block copolymers from the solution of the copolymers in an organic solvent, after the anionic polymerization reaction of predominantly monovinyl aromatic and predominantly conjugated diene, initiated by the alkali metal organ, either by means of a donor agent of protons in the case of a block copolymer prepared in a fully sequential manner, or by means of a coupling agent * in the case of an intermediate diblock copolymer prepared initially, in principle was known from the European patent application No, 0413403. For that European patent application, and in particular page 6, lines 7, 8 and lines 54-56, it was known to treat a cement of arbitrary copolymers or block copolymers of aromatic monovinyl and conjugated diene and a solvent that largely comprised cyclopentane, by coagulation of RE F: 24720 steam. However, a generally appreciated disadvantage of such a process, particularly if applied to block copolymers, aromatic monovinyl and conjugated diene derivatives and having a relatively low viscosity, was the formation of large agglomerations and severe fouling of the reactor and / or that the termination of such block copolymers proceeded with very low yields, and consequent additional recovery costs. On the other hand, it was generally known to those skilled in the art that alternate methods of terminating block copolymers having a relatively low viscosity and / or a relatively high poly (monovinyl aromatic) content, were involved with much capital investments. older due to the cost of additional equipment. A person skilled in the art will appreciate that just the need for block copolymers derived from predominantly monovinyl aromatic and predominantly conjugated diene having a relatively low viscosity, continued to grow for several modern end-use applications of block copolymers, for example, sensitive adhesives. the pressure, while the economy of the finished block copolymers called for a reduction in costs, that is, higher yields, shorter cleaning times to avoid or reduce fouling, and a lower capex. Therefore, an object of the present invention was to provide an improved process for the coagulation termination of (co) polymers, and in particular those that are derived from predominantly conjugated diene and / or predominantly monovinyl aromatic. It will be appreciated that with the term "process for finishing (co) polymers by coagulation", as used throughout the present specification, it is intended to cover mainly all the termination processes in which a solution of a solvent organic containing (co) polymer is mixed with an immiscible liquid, in which the polymer is substantially insoluble, under simultaneous heat supply to volatilize a substantial part of the organic solvent by a hot fluid, such as steam or a hot inert gas, for example, nitrogen. Of these embodiments, the most preferred is the steam coagulation termination process. As a result of extensive research and extensive experimentation, we have surprisingly found the improved process we wanted. Accordingly, the present invention relates to a process for the coagulation termination of (co) olimers, and in particular those which are derived from predominantly conjugated diene and / or prediominantly monovinyl aromatic, by the coagulation of the cement containing (co) polymer, in the presence of polyvinyl alcohol as a dispersant. Preferably the present invention relates to a process for the termination of (co) polymers by steam coagulation, and more preferably with a process for the termination by vapor coagulation of block copolymers comprising at least one block derived from predominantly diene conjugate and at least one block derived from predominantly aromatic monovinyl. The polyvinyl alcohol to be used in the process of the present invention has weight average molecular weight in the range of 200 to 200,000, and preferably from 3000 to 30,000, and may have an average degree of hydrolysis in the range of 25 to 98% and preferably from 60 to 90%. The polyvinyl alcohol is added in amounts of 10 to 10,000 ppm with respect to the weight of the coagulation water, and preferably from 25 to 1000 ppm and more preferably from 40 to 100 ppm. According to the preferred embodiment of the present process, the polyvinyl alcohol is introduced into the reaction furnace by contact by means of a small jet of water, but it will be appreciated that according to other embodiments, the APV can be introduce the contactor through the premixed cement. It was surprisingly found that the use of polyvinyl alcohol as a dispersant during a coagulation termination process, and in particular a steam coagulation termination process for block copolymers containing at least one block of predominantly conjugated diene and at least one block of predominantly aromatic monovinyl, it can avoid the formation of large agglomerations and severe fouling of the reactor for low viscosity block copolymer grades, while the concentration of block copolymer in the slurry could be increased significantly, for example from 1 wt% to 4.5 wt% when 50 ppm polyvinyl alcohol was applied in the coagulation water. The use of polyvinyl alcohol dispersant will allow higher yields due to the increased concentrations of block copolymers in the aqueous slurry, and shorter cleaning times due to fouling of the reactor. With the use of the term "predominantly" as applied throughout this specification, it is implied that the specified monomer can be used in substantially pure form or can be intentionally mixed with certain specific minor amounts of comonomer (<20% by weight), which may be structurally similar or structurally different from the main monomer constituent of a block segment. For example, the major constituent 1,3-butadiene can be mixed with. minor amounts of other conjugated dienes, such as isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene or 2,3-dimethyl-1,3-pentadiene , or their mixtures, or with a structurally different comonomer, such as aromatic monovinyl. The main component of the aromatic monovinyl monomer will usually be selected from styrene, optionally mixed with minor amounts of α-methylstyrene; 3, 5-diethylstyrene, 4-n-propylstyrene, 2,4,6-trimethylstyrene, 4-phenylstyrene, 4-methylstyrene, 3,5-diphenylstyrene, 1-vinylnaphthalene; 3-ethyl-1-vinylnaphthalene, -phenyl-1-vinylnaphthalene, or mixtures thereof, or mixed with isoprene, butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1, 3-pentadiene or 2,3-dimethyl-1,3-pentadiene, or mixtures thereof. The block copolymer segment derived from such monomer mixtures may have a substantially arbitrary or progressive structure. If it exists, preferably the main monomer constituent of a specific segment of the block is mixed with the main monomer component of the other segment of the block, for example, butadiene mixed with styrene. It will be appreciated that the process of the present invention is applied to cements (co) polymers, of which the polymer may preferably consist of a predominantly poly (conjugated diene), or of a copolymer of conjugated diene and monovinyl aromatic. More preferably the process is used for the finishing of block copolymers having a bonded content of poly (monovinylaromatic) within the range of 15 to 90% by weight and more in particular of 25 to 85% by weight. Another particular category of block copolymer grades to be preferably finished by the process of the present invention is formed by low viscosity block copolymer grades, for use in adhesive compositions. This category of block copolymers comprises in particular block copolymers of the type ABA or (ABl) n X, wherein the component A represents a predominantly polystyrene block having an average molecular weight ranging from 5,000 to 30,000, wherein B represents a predominantly poly block
(isoprene) and / or poly (butadiene), which optionally may have been selectively hydrogenated, and having an average molecular weight in the range of 30,000 to 70,000, wherein Bl represents a predominantly poly (isoprene) block segment and / or poly (butadiene) having an average molecular weight in the range of 15,000 to 35,000, and which optionally may have been selectively hydrogenated, wherein X is the residue of a coupling agent that does not contain halogen and n > 3, whose overall molecular weight is in the range of 50,000 to 300,000 and wherein the contents of styrene bound in the block copolymer is in the range of 10 to 50% by weight relative to the weight of the complete block copolymer. More particularly, the average molecular weight of the B block of the ABA specific triblock copolymers mentioned will be in the range of 30,000 to 50,000, while the average molecular weight of the A block will be in the range of 8,000 to 25,000, the overall molecular weight of the copolymer will be in the range of 50,000 to 200,000, and component A is present in amounts ranging from 10 to 30% by weight. It will be appreciated that a main product
(formed by a) triblock copolymer ABA or (a) radial block copolymer (ABl) nX may be accompanied by a variable amount of a diblock copolymer ABl, which is the inevitable result of coupling the AB1 living block copolymers prepared with an agent coupling to form (ABl) nX or ABA, due to a coupling efficiency of < 95%, or that has been intentionally co-produced with or added to a fully sequential polymerized triblock copolymer, in order to adapt its processability for the purpose of the preparation of hot melt adhesive compositions. Such diblock copolymers present can have an average molecular weight of 40,000 to 80,000. It was found that the process according to the present invention can be successfully applied with cements (co) polymers comprising a large variety of inert organic solvents, in which the preceding polymerization was carried out. More particularly it was found that the process can be successfully applied with cements comprising block copolymers containing pure blocks of styrene and blocks of butadiene and / or isoprene. Solvents can usually be selected from cyclohexane or cyclopentane, optionally mixed with minor amounts (< 50% by volume) of solvents selected from linear or branched alkanes having from 5 to 7 carbon atoms, such as n-hexane, isopentane or n-pentane. The process according to the present invention is usually applied by mixing the cement with steam, of a pressure in the range of 3 to 12 bara and a temperature in the range of 120 to 200 ° C in a contact reaction furnace, and the The mixture is taken to a coagulator, which is usually operated at a temperature in the range of 90 to 120 ° C and at a pressure of 1.0 to 2.5 bara, and where the majority of the solvent is removed by autoevaporation and condenses. The resulting rubber slurry usually contains from 3 to 5% by weight of polymer and in particular of elastomer, and approximately 5% by weight of residual solvent on polymer, which is still eliminated in one or more stages of autoevaporation, operating in a temperature range of 95 to 105 ° C, and 1 to 1.5 bara, until the solvent content is 0.2% by weight or less. Normally the residence time in each autoevaporation tank is in the range of 20 to 40 minutes. It is true that US patent 4,154,923 disclosed a process for removing water from an aqueous slurry of polymer beads, and in particular polyester beads, where the slurry contained polyvinyl alcohol dispersion stabilizer. This process included the stages of: (a) precipitation in the slurry of an insoluble organic destabilizer, with molecular weight of at least 200, from a soluble starting compound containing ionisable solubilizing groups, in an amount sufficient to flocculate and promote the removal of water from the slurry, and (b) remove water from the treated slurry in that way proceeding to physically separate water from it, at a temperature of at least 50 ° C, to form one. soft cake of polymer beads, essentially free from alcohol (poly) vinyl dispersion stabilizer. However, on the use of poly (vinylalcohol) only those skilled in the art were advised that it was inconvenient, since the polymer slurries that had to be recovered and that contained poly (vinylalcohol) required an additional stage of precipitation with destabilizer for preparing the poly (vinyl alcohol) free polymer. Therefore, persons skilled in the art would rather move away from its application to the finished one by coagulation. The invention can be further illustrated by the following examples, without however restricting its scope to these embodiments. Example 1 1500 grams of Cariflex TR-1112 was charged to a 25 liter stainless steel reactor equipped with a stirrer, and 14.1 liters (11.0 kg) of cyclohexane and 9 liters (5.7 kg) of iso-pentane were added. The reactor was pressurized with nitrogen at 1 barg, and stirred for 12 hours. The resulting solution was transported to a vessel and stored while stirring under a nitrogen pressure of 4 barg. A 100 liter coagulation vessel equipped with an agitator was charged with 30 liters of demineralized water. To this reaction were then added 1616 grams of polyvinyl alcohol having an average molecular weight (Mw) which was in the range of 9000 g / mol to 10000 g / mol, and an average degree of hydrolysis of 80% as a solid. The aqueous solution was stirred while heating with high pressure steam, and a mixture of the high pressure steam and the hydrocarbon thermoplastic elastomer solution was injected into the coagulation vessel at a rate such that a continuous flow of water was obtained. Distillate consisting of water and hydrocarbon solvent. The contents of the coagulation vessel were discharged and collected. The wet polymer was dried using hot air of about 45 ° C for 8 hours. 1480 grams of white granules were obtained. The coagulation of Cariflex TR-1112 without the addition of polyvinyl alcohol, carried out under conditions similar to those previously described, resulted in
tz large agglomerations and severe fouling of the coagulation vessel. Example 2 9 liters (7.0 kg) of an experimental thermoplastic elastomer (10 wt.% In cyclohexane, branched SBS, Mw step I 35000 g / mol, 70 wt.% Polystyrene content) were charged into a tank, and added 6 liters (3.7 kg) of iso-pentane. The resulting solution was sd while stirring under 4 barg of nitrogen pressure. A 100 liter coagulation vessel was charged with 30 liters of demineralized water. To this reacwere then added 1.50 grams of polyvinyl alcohol with average molecular weight (M) in the range of 9000 g / mol to 10000 g / mol, and an average degree of hydrolysis of 80% as a solid. The aqueous solution was stirred while heating by high pressure steam injection at a temperature in the range of 95 ° C to 100 ° C, in about 30 minutes. A mixture of high pressure steam and hydrocarbon thermoplastic elastomer solution was injected into the coagulation vessel at a rate that allowed obtaining a continuous flow of distillate, consisting of water and hydrocarbon solvent. Simultaneously, an aqueous solution containing 0.7% by weight of the polyvinyl alcohol described above was added to the high pressure steam / polymer solution mixture, -a > .An average rate of 10 ml / min. The content:; delt'H ^ -a? ilen-te < The coagulation was discarded and collected. The wet polymer was dried using hot air of about 45 ° C for 8 hours. Approximately 700 grams of white granules were obtained. The coagulation of the same experimental thermoplastic elastomer (10% by weight in cyclohexane, branched SBS, Mw stage I 35000 g / mol, 70% by weight polystyrene content) without the addition of polyvinyl alcohol, carried out under conditions similar to described above, resulted in the formation of very large agglomerations that led to problems in the coaguladischarge and in the drying stage.