| 摘要 |
#CMT# #/CMT# Continuous direct evaporation and degassing of elastomer-containing polymer solution using horizontally operating heatable-mixing kneader (1)/kneading machines, comprises: concentrating the elastomer-containing polymer solution containing volatile components, including solvents and solvent systems or unreacted monomers and volatile catalysts-, initiators- and polymerization-residues; recovering directly from several successive process steps with different process parameters, in sequentially-connected shaft mixing kneaders; and providing a desired shape for further processing. #CMT# : #/CMT# Continuous direct evaporation and degassing of elastomer-containing polymer solution using horizontally operating heatable-mixing kneader (1)/kneading machines, comprises: concentrating the elastomer-containing polymer solution containing volatile components, including solvents and solvent systems or unreacted monomers and volatile catalysts-, initiators- and polymerization-residues; recovering directly from several successive process steps with different process parameters, in sequentially-connected shaft mixing kneaders, which are operated at different pressures, temperatures, speeds, filling levels (8) and torque values; and providing a desired shape for further processing. #CMT#USE : #/CMT# The method is useful for continuous direct evaporation and degassing of elastomer-containing polymer solutions using horizontally operating heatable-mixing kneader/kneading machines. #CMT#ADVANTAGE : #/CMT# The method: is carried out at the process temperature, where the elastomeric polymer is not overheated, not chemically modified, does not undergo damage, and do not change its polymer properties or turn into a liquid state; is continuous, energy efficient and low emission process; does not require auxiliary materials including water; enables the flow rates up 10 t of polymer/hour; and avoids foaming. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The figure shows a schematic representation of continuous direct evaporation and degassing of elastomer-containing polymer solution. 1 : Mixing kneader 2 : Dosing device 4 : Degasser 5 : Condenser 8 : Filling levels #CMT#INSTRUMENTATION AND TESTING : #/CMT# Preferred Components: The horizontally operating, large-volume, self-cleaning mixing kneader is used for the process steps of the concentration, the process space of the mixing kneader is temperated over a double mantel and over the kneader shaft, the kneader shaft with radially mounted, heatable disc segments at which attached shear elements are fitted, and are designed such that they are homogeneously mixed with the static elements, preferably dough hook in the housing, the polymer solution of different composition and the removal of volatile components takes place and thus prevent foaming. The horizontally operating, large-volume, self-cleaning mixing kneader is used for the process steps of the degassing and the polymer-shredding, the process space of the kneader is thermostated over a double mantel over the shafts and its disk segments, with two co-rotating shafts with equal or unequal speed and radially mounted, heatable disc segments at which attached shear elements are fitted, which are designed such that they cut or break open with each other by running past, or over both the polymer, and thus form crumbs and new surfaces on the polymer crumb are produced. #CMT#POLYMERS : #/CMT# Preferred Method: The polymer solution in the first step is concentrated to a solution with polymer content of 5-50%, preferably 10-25% by the dissipative kneading energy incorporated by the kneading elements, and until the content of volatile component is 20-1%, preferably 15-2%. The volatile components evaporate and the fumes reach at least one dome in a condenser, where it is condensed, collected and discharged from the process, while the concentrated polymer solution from the mixing kneader is continuously discharged via a screw system. The discharged, concentrated polymer solution is treated in a second mixing kneader and a degasser (4) such that the volatile components from the polymer solution can be evaporated to the point that the polymer forms a polymer elastomer crumbs, where the speed of mixing kneader and filled volume of the product, and the process conditions are chosen such that no reagglomeration and further degassing of the polymer crumb is carried out on the predetermined residual content of volatile component including solvents- or monomer content and other volatile residues (2%-1 ppm, preferably 2000-100 ppm). The polymer in a third mixing kneader discharged from the second step, degassed by the degasser, is treated in the polymer-shredders by appropriate choice of the speed and the construction of dynamic kneader elements so that the desired form of polymer crumbs results and further processing with the baler is also possible. The process of direct evaporation, degassing and shaping are carried out as a batch process, as a semi-batch process or as a continuous process. The direct evaporation is used for polymer solution containing temperature-sensitive elastomer, preferably polymer solution of butadiene-derived homo- or copolymers, without damaging the polymer. The process of direct evaporation is operated without coagulation and stripping, and with or without coagulation- and stripping aids. The method is carried out either at higher-, normal- or low pressure, or with or without using inert- or carrier gas, at a process temperature of 50-150[deg] C and for a time duration of few minutes to several hours. The method is carried out at different rotational speeds and torque values, preferably at speed of 5-150 revolutions per minute and specifically based on the apparatus volume, and torque value of 5-100 Nm/l. The mixing of elastomer-containing polymer solution with concentrated polymer solution is carried out directly after the introducing in the step of concentration without foam formation. The largest part of required, which is higher than the mechanical energy is incorporated via the dissipative kneading energy of kneading elements without damaging the polymer. The removal of the solvent-containing gases released during the process is carried out through at least one dome of the kneader, the subsequent process technology of further treatment of these gases by condensation of solvents or solvent mixtures, and further treatment of non-condensable residual gases. The evaporation of the polymer is carried out until the formation of elastomeric polymer crumbs in a bulk density range of 100-300 kg/m 3>of mixing kneader volume, a speed range of 5-150 revolutions per minute, a peripheral speed of the axial shear elements on the kneading and mixing shafts stationary disc segments of 0.25-5 m/s. The method is carried out at sufficiently impulsive gradient under vacuum and without or with the aid of liquid or gaseous degassing auxiliaries for further degassing of the crumbs to the predetermined residual content, without the maximum allowed polymer temperature, preferably 70-120[deg] C to cross, and without the polymer damaging. The concentrated polymer solution is discharged from the first step and/or the degassed polymer is discharged from the second step by means of a conveyor directly integrated or flanged on the mixing kneader and then passed directly through a further process step attached to the conveyor, after the second step, a one- or two-shaft polymer-shredder that can also be the kneader, the degassed polymer is processed into the desired shape and prepared for further processing. A one-or two-shaft vertical or horizontal auger system is equipped by a conveyor directly integrated or flanged on the mixing kneader. The auger system can be mixed with a mixing zone, over the degassing agents or additives, and with a gas-tight tamping zone, with which the process area can be separated against pressure or vacuum from the atmosphere or an upstream or downstream step. The concentrated polymer solution and/or the degassed polymer are discharged into the next stage of the process. #CMT#EXAMPLE : #/CMT# Co-rotating processor (CRP-10) with a void volume of 12.4l was used. The empty CRP was heated to 118[deg] C and at a pressure of about 13 mbar. The shafts of the CRP was made to run at a speed of 40/50 revolutions per minute and the idling torque of the CRP was determined at 152 Nm. Then 1,4-cis-polybutadiene solution in toluene (15 mass-%) was used as the elastomer-containing polymer solution. Simultaneously, the polybutadiene solution was processed through subsequent expeller-expander-drying technique after stripping. The polymer solution was poured into a storage container with an inflow of 300-500 g/minute. During the inflow of the polymer solution into CRP, the toluene and was condensed using cooling water in the intervening condenser, which was drained into a reservoir and discontinuously measured. The torque rises steadily up to a value of 386 nm to obtain the degassed product. |
