Method of removing volatiles from raw polymerizate
(57) Abstract:Usage: in the chemical industry to remove unreacted monomer upon receipt of polymethylmethacrylate. The inventive method of removing volatiles from the raw polymerize containing less than 50 wt.% methyl methacrylate) or a copolymer of 80-99 wt.% of methyl acrylate and/or ethyl acrylate, by single-stage heating to 200-270°C and evaporation under a pressure of 10-150 mm RT.article 1 Il. The invention relates to the chemistry of macromolecular compounds, namely, the processes of obtaining polymethylmethacrylate or copolymers. At the stage of removal of unreacted monomers.There are various ways to remove volatile components upon receipt of polyvinyl products.The closest to the technical nature of the proposed method is a method of removing volatiles from raw polymerizate upon receipt of polystyrene . Polymerizate contains less than 50 wt.% by weight of polymerizate polystyrene, organic solvent and unreacted monomer. According to the way raw polymerizat multi-stage heated under reduced atmospheric pressure with subsequent evaporation of polymerizate volatile and separation shall provide for re-heating polymerizate cannot be used for polymethacrylate raw polymerizaton.The aim of the invention is to simplify technology for the removal of volatile crude polymetylmetacrylate of polymerizaton.This goal is achieved by heating the raw polymerizate containing less than 50 wt.% by weight of polymerizate poly (methyl methacrylate) or a copolymer of 80-99 wt.% of methyl methacrylate and 1 to 20 wt.% of methyl acrylate and/or ethyl acrylate. Crude polymerizate heated at one stage to 200-270aboutC at a pressure below atmospheric and evaporated under a pressure of 10-150 mm RT.article Crude polymerizate may contain an amount of solvent sufficient to maintain below 50% concentration of the solid phase, preferably below 40%. You can use any solvent with a low boiling point, for example, saturated or aromatic hydrocarbons, in particular, hexane, heptane, octane, benzene, xylene, cyclohexane, cyclodecane, isooctane, and mixtures thereof, such as nafta, etc. Typically use solvents having a boiling point at atmospheric pressure of about 40-225aboutWith, preferably, about 60 to 150aboutC. it is Recommended to use a solvent having a boiling point close to the boiling point of the main monomer of methyl methacrylate, to avoid the need for intermediate francioni range of boiling points, that reduces the likelihood of contaminants in the recycled mixture.The invention is well applicable to copolymers of methyl methacrylate and ethyl acrylate or methyl acrylate.The drawing shows a circuit for implementing the method.Crude polymerizate drawn from polymerizate 1, is transferred by pump 2 through the transmission line 3 in the heater 4 devolatilization. Crude polymerizate recommended to pass through a tube shell-tube heat exchanger to raise the temperature of the load approximately in the range 220-260aboutWith this heat exchanger the heat transfer of the heating fluid, for example, the flow of hot oil, which is introduced into the shell portion of the heat exchanger through line 5. Crude polymerizate heated in the heat exchanger 4, is passed through the transmission line 6 in the rapid evaporation tank 7 in section devolatilization. Transmission line 6 has a reverse pressure regulating valve 8, responsive to the output pressure from the gear pump 2. The pressure that is maintained in a damp polymerizate, enough to sustain a mixed two-phase system of liquid and vapor. In practice, a significant portion of the solvent is maintained in liquid phase in the heater 4 heat transfer in the heater of devolatilization. When the heat exchanger is excessive evaporation, the crude polymer can be cooled to a temperature evaporation or below this temperature, which leads to the formation of a solid phase, which quickly forms a crust on the surfaces of heat transfer. This is eliminated by maintaining sufficient back pressure in the raw polymerizate in the heater 4.The necessary pressure for raw polymerizate can be determined experimentally by heating the sample raw polymerizate to the temperature at the inlet of the heater in a laboratory pressure vessel while maintaining sufficient pressure in the sample to exclude significant evaporation. Then the pressure is slowly reduced in the sample by observing the liquid phase of the sample to determine the pressure at which it starts curing. This pressure is the minimum pressure that must be maintained at the input of the heater 4.You should ensure that raw polymerizat not heated to a temperature above 270aboutC, since higher temperatures discolor the product. However, for effective devolatilization need to crude polymerizate was heated to about 240-250aboutWith and, therefore, LASS="ptx2">Crude polymerizate subjected to rapid evaporation in the tank devolatilization 7, which is maintained at a pressure below atmospheric sufficient to deformirovaniya almost all of the solvent, unreacted monomer and by-polymeric product with a low boiling point from the finished polymer product. It is recommended to use the spray to ensure effective devolatilization. As a rule, devolatilization is maintained at an absolute pressure of from about 10 to 150 mm RT.art., preferably at 50 mm RT.article The pair is removed from the vessel 7 through the pipe at its upper dome, pass them on line 9 recirculation distillation apparatus 10, which represents a column having two zones of the nozzle 11 and 12 and located beneath the evaporator 13. Hot couples enter into the lower zone 12 of the nozzle and partially condensed by contact with recycled condensate from lines 14 and 15. The velocity obtained by counterflow cooling condensate line 14 regulate by means of the valve 16 to maintain a predetermined liquid level in the evaporator 13. The solvent, some Monomeric products and polymer products with a low boiling point are collected in the evaporator 13 and a flow condenser 19. A counter-current condenser 19 is a shell-tube heat exchanger, and solvent vapours condense and collect in counterflow fluid vessel 20. Non-condensable components is passed through line 21 into the vacuum system 22 via the control valve 23. Part of the condensed solvent is returned to the recirculation distillation apparatus as a reverse flow in the line 14, and the rest of the condensed solvent is recycled to the process through line 24, closing the cycle of solvent in the process. The finished polymer, which typically contains residual monomer and solvent in a quantity of less than 1.0 wt.%, preferably less than 0.1 wt.%, out through the bottom of the reservoir 7 devolatilization through the pump 25 and sent for final processing.P R I m m e R. example illustrates the method used for installation, with a capacity of 12000 tons of polymethylmethacrylate in the year. Raw material is a mixture with the following composition, wt.%:
The monomers 39,6
The solvent 60,0
The monomers are a mixture of methyl methacrylate (97%) and methyl acrylate (3%). The raw material is produced by mixing fresh monomers of the present composition with recycle volatile received from desolately ereset, remote after polymerization from the reactor has the following composition, wt.%:
The monomers of 6.6
The solvent 60,0
The polymer 33,0
The conversion of monomer in the process, on the basis of supply of raw materials (including recycling), is 83.8 percent.Crude polymerizate transferred from the reactor to the heat exchanger of devolatilization. To the shell of the heat exchanger serves hot oil at a temperature of 270aboutC and extracted with 260aboutC. the temperature of the raw polymerizate increase from 95 to 260aboutWith, and the pressure of raw polymerizate inside of the heat exchanger is maintained at a level between 300 and 600 mm RT.art., which is sufficient to prevent evaporation and the formation of the foam crusts in the heat exchanger.Heated polymerizat miss in one vacuum chamber, in which its pressure is reduced to 60-80 mm RT.art., and the solvent and unreacted monomers are subjected to instantaneous evaporation, leaving a polymer product having the following composition, %:
The polymer 99,82
The monomers 0,10
The solvent 0,08
The polymer is passed through a static mixer, which adds traditional additives such as UV stabilizers, internal lubricants, plasticizers, and so forth, depending(l loss of mass at 300aboutWITH
for 1/2 h in nitrogen)
The content of residual
Ash content Not found
The melt index (ASTM D-1238): 2,5
(ASTM D-1003): 92,7
Teplosnabjenie (ASTM D-648
at 264 lb/in2): 90aboutWITH
Impact strength Izod 2,2
(ASTM D-256): kg-cm/snakes METHOD of REMOVING VOLATILES FROM RAW POLYMERIZATE containing less than 50% by weight of polymerizate vinyl polymer, an organic solvent and unreacted monomer by heating raw polymerizate at a pressure below atmospheric, with subsequent evaporation of polymerizate volatile and selection of a polymer melt with a volatile content less than 1%, characterized in that the vinyl polymer used poly (methyl methacrylate) or a copolymer of 80 to 99 wt. % of methyl methacrylate and 1 to 20 wt.% of methyl acrylate and/or ethyl acrylate, crude polymerizate single-stage heated to 200 - 270oC at a pressure sufficient to maintain liquid phase during heating and evaporated under a pressure of 10 to 150 mm RT.article
FIELD: polymer production.
SUBSTANCE: invention relates to removal of volatile impurities from epoxide resin used to manufacture of coatings. Method of invention resides in that container with epoxide resin is placed in tank with hot oil and heated to 100-110°C at stirring. When temperature of resin achieves 50°C, air is supplied to its lower layers.
EFFECT: increased degree of removing volatile impurities from epoxide resin and safety of process.
FIELD: rubber industry.
SUBSTANCE: halogenated butyl rubber is recovered from hydrocarbon solution via multistage water degassing including granule formation stage, final distillation of hydrocarbons from rubber in several steps, in which pressure is gradually raised and reduced in final step, while vapor-gas mixture formed is ejected into one of preceding steps. Vapor-gas mixture from the last step, prior to be ejected, is fed into two cooled partial condensers, one of which receives initial solution of halogenated rubber transferred further into process and the other receives coolant amount of which being controlled with regard to specified pressure or temperature in the last distillation step.
EFFECT: reduced consumption of water steam when recovering halogenated butyl rubber and controlling parameters in the last distillation step while specified process parameters in preceding steps being preserved.
3 cl, 1 dwg, 3 tbl
FIELD: polymer production.
SUBSTANCE: invention relates to a process for continuously producing alkylene polymer. e.g. styrene, and comprises bulk polymerization of aromatic alkylene resulting in formation of molten polymer mass, which is then processed to remove volatile products in at least two consecutive steps carried out such as to separate polymer from unreacted monomers and oligomers at least partially formed during polymerization. More specifically, process comprises passing first gaseous stream, isolated from polymer in the first volatiles removal step, to the first zone Z1 for direct concentration and fractionation, withdrawing from the upper part Z1 gaseous stream G1 including essentially monomer, and withdrawing liquid stream L1 from the bottom Z1, reach in oligomers. A portion of this liquid stream L1 is separated, cooled, and then returned to Z1 in a manner that, because of coming into direct contact with first gaseous stream, a partial condensation proceeds in Z1. Process further comprises passing second gaseous stream, isolated from polymer in the second volatiles removal step, to the second zone Z2 for direct concentration and fractionation. Another portion of liquid stream L1 isolated from Z1 is also passed to the same zone in a manner that, because of coming into direct contact with second gaseous stream, a partial condensation proceeds in Z2. From the upper part of Z2 is withdrawn gaseous stream G2 including monomer while, from the bottom Z2, liquid stream L3 including essentially oligomers is taken off.
EFFECT: enabled continuity of production.
2 cl, 2 dwg
SUBSTANCE: present invention relates to a method for polymerisation of ethylene or copolymerisation of ethylene with other 1-olefins. The invention describes a method for polymerisation of ethylene or ethylene with other 1-olefins in accordance with which ethylene polymerises in the presence of a catalyst in a gas-phase reactor (1) with formation of polymer particles. In order to tap polymerisation heat, there is a circulating reaction gas which contains propane and non-polymerised ethylene in which polymer particles are continuously or discretely output from the reactor (1). Polymer particles are separated from the larger portion of the accompanying gas and degassed. Gas is released from the captured fine particles. Gas is separated from the low-boiling fraction which contains ethylene or from the high-boiling fraction which contains other 1-olefins or alkanes with 4-12 carbon atoms at the first separation step. The propane fraction is separated at the second separation step and then used to degas polymer particles coming from the reactor, where partial pressure of ethylene in the propane fraction used for degassing is less than 6000 Pa under degassing conditions, and total partial pressure of other 1-olefins and alkanes with 4-12 carbon atoms in the propane fraction is less than 10000 Pa. Described also are apparatus for realising the said method (versions), as well as use of propane in which the fraction of ethylene, which is expressed through partial pressure, is less than 6000 Pa under degassing conditions, and the fraction of 1-olefins and alkanes with 4-12 carbon atoms, expressed through partial pressure, is less than 10000 Pa under degassing conditions, and which is obtained from the gas coming out of the gas-phase polymerisation reactor together with polymer particles, for degassing particles of ethylene homopolymers or copolymers in the method described above.
EFFECT: tapping a large amount of heat from the reactor, sufficient for degassing output polymer particles, high extraction ratio of the reaction gas.
18 cl, 2 dwg, 1 tbl, 2 ex
SUBSTANCE: invention relates to synthesis of highly stable, chemical-resistant perfluoropolyesters based on tetrafluoroethylene which are used as a base for low-temperature oil lubricants for space-rocket equipment. The invention describes a method of producing polytetrafluoroethylene oxide through photooxidation of tetrafluoroethylene with oxygen under UV radiation in the presence of a solvent and subsequent solvent distillation. The method is distinguished by that the process is carried out at temperature between minus 40°C and minus 60°C. The solvent used is perfluorotriethylamine. After solvent distillation, the product undergoes thermal treatment at 300-350°C and stabilisation with fluorine at 180-260°C.
EFFECT: design of an efficient method of producing highly stable chemical-resistant perfluoropolyesters based on tetrafluoroethylene.
1 cl, 2 ex, 2 tbl
FIELD: machine building.
SUBSTANCE: there is carried out reaction of co-polymerisation of isobutylene and isoprene producing butyl of rubber in suspension. Suspension of butyl rubber is pressed in a zone of separation. A two-screw extruder with screws of full engagement rotating in one direction is used for pressing. Extracted liquid non-aqueous reaction medium is transported beyond the zone of separation and outside a reaction vessel for re-cycle. Pressed suspension of butyl rubber is directed to a zone of suspension processing. The suspension processing zone is in an evaporating reservoir. The device for butyl rubber production consists of the reaction vessel, of the pressing separator, of the evaporating reservoir and of a pipeline. The pipeline transports liquid non-aqueous reaction medium beyond the reaction vessel. The two-screw extruder functions as a pressing separator. The facility for transfer of butyl rubber from the reaction vessel into the evaporating reservoir consists of a cylinder, an inlet port, and of an outlet port. The facility also includes a set of screws of full engagement rotating in one direction, a motor, a reducer and the pipeline. A liquid non-aqueous medium is transported via the pipeline from the zone of separation beyond the reaction vessel. The procedure ensures more efficient separation and direction of cooled liquid reaction medium to recycle.
EFFECT: transporting of suspension of butyl rubber from reaction vessel into evaporating reservoir by means of self-cleaning two-screw extruder eliminates problem of clogging caused by rubber adhesion to device surface at suspension overflow.
16 cl, 7 dwg
SUBSTANCE: invention relates to a method of recuperating unreacted monomers contained in a stream of residual gas formed during synthesis of a copolymer of vinyl ester and ethylene. Described is a method of producing copolymers containing vinyl ester or ethylene or ethylene unsaturated monomers via radical emulsion or suspension polymerisation in an aqueous medium at absolute pressure between 5 and 100 bars. At the end of polymerisation, the reaction mixture is throttled with reduction of its absolute pressure to 0.1-5 bars. Unreacted monomers are recuperated from the residual gas through multi-step fractionated condensation with deep cooling. At the first condensation step, water vapour is condensed at temperature ranging from -90 to -60°C, and at the third condensation step, ethylene is condensed at temperature ranging from 140 to 100 °C.
EFFECT: design of a method which enables extraction of valuable substances from the formed residual gas, where the said substances can be cheaply recycled.
9 cl, 2 dwg, 1 tbl, 1 ex
SUBSTANCE: method involves (1) bringing polyolefin from a polymerisation reactor into contact with a countercurrent of saturated steam in order to steam gases from said polyolefin and form condensed steam on particles of said polyolefin; (2) drying polyolefin particles with a countercurrent of dry inert gas while keeping polyolefin particles in fluidisation conditions through said stream of dry inert gas. Polyolefin cools due to evaporation of said condensed steam. The dwell time of said polyolefin at step (1) is equal to 10-45 minutes.
EFFECT: efficient deactivation of catalyst components and removal of unreacted monomers and heavy hydrocarbons from polyolefin powder from a polymerisation reactor.
13 cl, 5 dwg, 1 tbl, 3 ex
SUBSTANCE: method of degassing an aromatic polymer with an alkylene group is described, in which: a) a product aromatic polymer with an alkylene group in form of a mass of molten polymer is provided, also containing an aromatic monomer with an alkylene group, b) the mass of molten polymer is fed to a first degassing step to obtain a first gaseous stream containing an aromatic monomer with an alkylene group and oligomers, and a second stream containing the remaining part of the mass of molten polymer, c) water is added to the second stream as a washing substance to obtain a third stream containing the remaining part of the mass of molten polymer and water, d) the third stream is fed to a second degassing step to obtain a fourth gaseous stream containing water, an aromatic monomer with an alkylene group and oligomers, and a fifth stream containing a degassed mass of molten polymer, e) the fourth gaseous stream is fed to a separation step to obtain a sixth stream containing water and an aromatic monomer with an alkylene group, and a seventh stream containing oligomers, f) the sixth stream is fed to the separation step to separate an eighth stream containing water and a reduced amount of aromatic monomer with an alkylene group from a ninth stream containing the remaining part of the aromatic monomer with an alkylene group, g) the eighth stream is fed for azeotropic stripping in a stripping column in vacuum conditions using water vapour to obtain an overhead product stream containing water vapour and the main part of the aromatic monomer with an alkylene group which, together with the sixth stream, is fed to the separation step (f), and a bottom product stream containing water and a reduced amount of the aromatic monomer with an alkylene group, at least part of which is returned to step (c) as the washing substance.
EFFECT: reduced amount of water for recycling, reduced consumption of feed water used as the washing substance.
7 cl, 1 dwg, 1 ex
SUBSTANCE: invention relates to a method of producing a liquid poly-alpha-olefin. The method involves polymerisation in a reaction vessel of a C8-C12 α-olefin in the presence of a saturated C8-C12 hydrocarbon, hydrogen and a catalyst system to obtain an initial product of crude liquid poly-alpha-olefin. The C8-C12 hydrocarbon is fed into the reaction vessel in amount of 5-70 wt %. A stream rich in saturated hydrocarbon is then separated from the removed product of crude liquid poly-alpha-olefin. 5-35 wt % of the stream rich in hydrocarbon is removed from the polymerisation system in form of a blow-off stream to prevent accumulation of by-products and contamination. Saturated C8-C12 hydrocarbons are held in the reaction vessel with content of 8-40 wt % with respect to the combined weight of the C8-C12 alpha-olefin, saturated C8-C12 hydrocarbon and poly-alpha-olefin contained in the reaction vessel.
EFFECT: obtaining poly-alpha-olefins with desirable lubricant viscosity with high conversion, selectivity and output.
14 cl, 8 dwg, 7 tbl, 9 ex