摘要:
A process for the preparation of polycarbonate resins having a low yellowness index is described. The process involves converting phosgene with a sodium bisphenolate solution by means of a phase interface process performed with the exclusion of oxygen. The sodium bisphenolate solution used in the process has a dissolved oxygen content of
摘要:
A process for producing polymer pellets is disclosed. The process that is particular suitable for making polycarbonate pellets entails extruding a polymer melt, cooling the extrudate by contacting it with a cooling fluid and pelletizing the solidified polymer. The process is characterized in that the cooling fluid has a solids particle content of at most 10 ppm.
摘要:
The application relates to a process for the continuous production of phosgene from chlorine and CO with reduction of the carbon monoxide emission (CO emission).
摘要:
A process for producing phosgene having low content of carbon tetrachloride is disclosed. The process entails reacting carbon monoxide with chlorine in the presence of elemental carbon, in a reactor. Critically the temperature of the gas stream emerging from the reactor is restricted to 30 to 80° C. and its pressure, measured directly downstream from said reactor is restricted to 120 to 400 kPaabs. The phosgene thus produced has a content of carbon tetrachloride that is less than 150 ppm.
摘要:
A process for the production of polycarbonate is disclosed. The process, representing an improvement over the known interfacial polycondensation process entails introducing into the loop of a circulating reactor that additionally contains, a residence tank, an optional mixer, a pump, and a heat exchanger (i) an organic phase that contains a solvent for polycarbonate and phosgene and (ii) an aqueous phase that contains an aqueous lye solution, a dihydroxy compound and an optional monophenol to form an emulsion. Maintaining specified temperature and process conditions results in polycarbonate resin having good properties and in waste water that are characterized by their purity.
摘要:
An improvement in the continuous two-phase interfacial condensation process for preparing polycarbonate is disclosed. In the process that entails at least one diphenol, phosgene, at least one chain terminator, and optionally branching agents and is carried out in the presence of a catalyst the improvement comprising maintaining the concentration of the catalyst at a level of at least 0.012 mol per mol of diphenol.
摘要:
A method for the filling and optionally emptying transport containers with plastics granular materials is disclosed. A flexible plastics inliner is inserted into a transport container. A front side of the inliner includes at least one receiving flexible hose connection for filling the inliner with plastics granular material, at least one discharge hose connection for discharging blown in conveying air from the inliner, and at least one emptying hose connection for emptying plastics granular material from the inliner. The front side of the inliner also includes a protective liner. The cabin and the transport container are positioned at a decanting station, the cabin being adapted to transfer plastics granular material from the decanting station and decant the transferred plastics granular material into the transport container through the receiving hose connection. The transport container is then filled with plastics granular material utilizing the cabin.
摘要:
An apparatus for degassing plastic materials, e.g., high molecular weight polycarbonate solutions, is described. The apparatus includes a double-shaft extruder having a length-to-diameter ratio of less than or equal to 40, which comprises: (i) two co-rotating and meshing shafts; (ii) an intake opening; and (iii) upstream and downstream portions relative to the intake opening. The shafts of the extruder are designed with a double lead in a degassing zone, and with a triple lead in a pressure build-up zone. Each of the degassing and the pressure build-up zones are down-stream from the intake opening, and the pressure build-up zone is further down-stream than the degassing zone. Also described is a process for degassing plastic materials, which involves providing the described double-shaft co-rotating extruder, into which plastic material is fed, processed and degassed. Entraining agents, such as nitrogen, and other processing additives may be introduced into an extruder during the process of the present invention.
摘要:
A process of evaporating a viscous polymer solution is described. The process includes: (a) providing a viscous polymer solution including at least 30 wt. % of solvents and monomers; (b) introducing the viscous polymer solution into a heated helix (5), the heated helix having a vapor exit velocity of 200 to 300 m/s, (a film flow including a two-phase mixture of polymer melt, and solvent vapors and monomer vapors being formed within the helix); (c) forwarding the film flow from helix (5) into a heated vapor separator (6); (d) expanding the two-phase mixture of polymer melt, and solvent vapors and monomer vapors of the film flow within vapor separator (6) at an absolute pressure of 10 mbar to 800 mbar, (a bottom product including a concentrated melt of the polymer is formed within the vapor separator); and (e) withdrawing the bottom product from vapor separator (6). Each of the helix (5) and vapor separator (6) have a separate heating device, and each of heating device independently provides a temperature that is above the softening point of the polymer.
摘要:
The production of polycarbonate by the phase boundary method is disclosed. In accordance with the inventive process, a solution that contains polycarbonate is repeatedly washed with a washing liquid and the washing liquid is separated from the solution that contains the polycarbonate by separating elements and the solvent is then evaporated. The process is characterized in that the organic solution that contains the polycarbonate and the washing liquid are separated from each other after the first washing stage in a coalescer that contains hydrophilic packing.