摘要:
A process and apparatus for the (co) polymerization of styrene. The process is carried out by employing a liquid polymerization reaction mixture that includes styrene, in a mechanically stirred reactor in the form of a vessel comprising a side wall having the shape of a cylinder of revolution with a vertical axis (A), a bottom head and a top head that are joined to the side wall, the vessel being provided with a mechanical stirring device comprising (i) a central shaft of vertical axis coincident with the axis (A), connected to a drive system comprising a motor for rotating the central shaft, (ii) at least one baffle attached to the vessel, which process is characterized in that the baffle is away from the side wall of the vessel and takes the form of a cylinder of vertical axis and of rhomboidal cross section.
摘要:
The present invention relates to a process for stripping residual volatile compounds contained in a thermoplastic polymer. The process comprises (1) forming the polymer in the form of a melt flowing as a main stream, (2) forming a foaming agent in the form of one or more secondary liquid streams, (3) adding the secondary stream(s) to the main stream by spraying so as to divide each secondary liquid stream into several fractional streams and thus to form a polymer melt/foaming agent pre-mixture, (4) introducing the pre-mixture into a static mixer, then into an expansion chamber at reduced pressure so as to separate the polymer melt from the residual volatile compounds and from the foaming agent, and (5) withdrawing the polymer melt from the expansion chamber. The invention also relates to an apparatus for removing residual volatile compounds contained in a thermoplastic polymer. The apparatus comprises (i) a polymer melt feed line, (ii) an addition chamber into which the feed line runs and through which the polymer flows as a main stream, (iii) one or more lines for adding a foaming agent as one or more secondary liquid stream(s), which lines run into the addition chamber and have at their ends a spray device allowing each secondary liquid stream to be divided into several fractional streams, (iv) a static mixer having an inlet, connected to the addition chamber, and an outlet, and (v) an expansion chamber for separating the polymer melt from the residual volatile compounds and from the foaming agent, which chamber is connected to the outlet of the static mixer and is provided with a line for withdrawing the polymer melt and with a line for extracting the residual volatile compounds and the foaming agent.
摘要:
The present invention relates to a process and a device for the continuous manufacture of a polymer of an aromatic alkylene monomer e.g. styrene comprising a bulk polymerisation of the monomer and a devolatilization of the resulting polymer in at least two successive steps so as to separate the polymer from the unreacted monomer and the oligomers formed during the polymerisation. The process comprises conveying a first gas stream resulting from the first step of the devolatilization into a first zone Z1 for direct condensation and fractionation, removing a gas stream G1 comprising essentially the monomer from the top of Z1, and removing a liquid stream L1 rich in oligomers from the bottom of Z1, a portion of L1 being taken, cooled and then returned into Z1. It also comprises conveying a second gas stream resulting from the second step of the devolatilization into a second zone Z2 for direct condensation and fractionation, this zone being also fed with the other portion of L1, removing a gas stream G2 comprising the monomer from the top of Z2, and removing a liquid stream L3 comprising essentially the oligomers from the bottom of Z2. The process and the device are particularly suitable for continuously manufacturing a styrene polymer, a styrene copolymer having a high impact strength modified by grafting onto a rubber, an expandable polystyrene or an expanded polystyrene. The invention is useful for improving the separation of the unreacted monomer from the oligomers and the quality of the polymer when the unreacted monomer thus separated is recycled e.g. to the polymerisation.
摘要:
The present invention relates to a continuous process for polymerizing a vinyl monomer wherein a liquid reaction mixture flows through a tubular reactor equipped with a primary heat exchanger connected to a primary cooling loop where a primary coolant liquid circulates, optionally cooled by contact with a secondary heat exchanger fitted in the said primary loop and placed in a heat exchange zone of a secondary cooling device containing a secondary coolant liquid. The primary coolant liquid employed in the absence of a secondary cooling device or the secondary coolant liquid consists essentially of superheated water under pressure which produces low-pressure steam which preferably is recovered at least partly thermally or energetically.
摘要:
Process for devolatilization of a polymer of an aromatic alkylene, such as styrene and, in particular, an improved process using water as a stripping agent (i) in which the total amount of water to be disposed of can be reduced, (ii) which allows at least a portion of the water to be recycled as stripping agent, reducing make-up requirements for the stripping agent, and (iii) which allows at least a portion of the aromatic alkylene monomer in the water to be recycled to the polymerization process (via the devolatilization steps) rather than being disposed.
摘要:
Process and apparatus for the (co) polymerization of styrene. The process is carried out by employing a liquid polymerization reaction mixture that includes styrene, in a mechanically stirred reactor in the form of a vessel comprising a side wall having the shape of a cylinder of revolution with a vertical axis (A), a bottom head and a top head that are joined to the side wall. The vessel is provided with a mechanical stirring device comprising (i) a central shaft of vertical axis coincident with the axis (A), connected to a drive system comprising a motor for rotating the central shaft, (ii) at least one baffle attached to the vessel. The baffle is away from the side wall of the vessel and takes the form of a cylinder of vertical axis and of rhomboidal cross section.
摘要:
The present invention relates to a process for devolatilization of a polymer of an aromatic alkylene, such as styrene, and in particular, to an improved process using water as a stripping agent (i) in which the total amount of water to be disposed of can be reduced, (ii) which allows at least a portion of the water to be recycled as stripping agent, reducing make-up requirements for the stripping agent, and (iii) which allows at least a portion of the aromatic alkylene monomer in the water to be recycled to the polymerisation process (via the devolatilization steps) rather than disposed of.
摘要:
An expandable polystyrene composition in the form of beads is disclosed, comprising: (1) 100 parts by weight of a styrene polymer having in particular a weight-average molecular weight Mw ranging from 150 000 to 400 000 daltons, (2) from 3 to 20 parts by weight of a blowing agent, which is water or a mixture of water with at least one other blowing agent for example a hydrocarbon (3) from 0.1 to 12 parts by weight of at least one modified clay with an at least partially lipophilic nature. Also disclosed is a process for making the compositions.
摘要:
The present invention relates to-a process and a device for the continuous manufacture of a polymer of an aromatic alkylene monomer e.g. styrene comprising a bulk polymerisation of the monomer and a devolatilization of the resulting polymer in at least two successive steps so as to separate the polymer from the unreacted monomer and the oligomers formed during the polymerisation. The process comprises conveying a first gas stream resulting from the first step of the devolatilization into a first zone Z1 for direct condensation and fractionation, removing a gas stream G1 comprising essentially the monomer from the top of Z1, and removing a liquid stream L1 rich in oligomers from the bottom of Z1, a portion of L1 being taken, cooled and then returned into Z1. It also comprises conveying a second gas stream resulting from the second step of the devolatilization into a second zone Z2 for direct condensation and fractionation, this zone being also fed with the other portion of L1, removing a gas stream G2 comprising the monomer from the top of Z2, and removing a liquid stream L3 comprising essentially the oligomers from the bottom of Z2. The process and the device are particularly suitable for continuously manufacturing a styrene polymer, a styrene copolymer having a high impact strength modified by grafting onto a rubber, an expandable polystyrene or an expanded polystyrene. The invention is useful for improving the separation of the unreacted monomer from the oligomers and the quality of the polymer when the unreacted monomer thus separated is recycled e.g. to the polymerisation.
摘要:
The present invention relates to a process for stripping residual volatile compounds contained in a thermoplastic polymer. The process comprises (1) forming the polymer in the form of a melt flowing as a main stream, (2) forming a foaming agent in the form of one or more secondary liquid streams, (3) adding the secondary stream(s) to the main stream by spraying so as to divide each secondary liquid stream into several fractional streams and thus to form a polymer melt/foaming agent pre-mixture, (4) introducing the pre-mixture into a static mixer, then into an expansion chamber at reduced pressure so as to separate the polymer melt from the residual volatile compounds and from the foaming agent, and (5) withdrawing the polymer melt from the expansion chamber. The invention also relates to an apparatus for removing residual volatile compounds contained in a thermoplastic polymer. The apparatus comprises (i) a polymer melt feed line, (ii) an addition chamber into which the feed line runs and through which the polymer flows as a main stream, (iii) one or more lines for adding a foaming agent as one or more secondary liquid stream(s), which lines run into the addition chamber and have at their ends a spray device allowing each secondary liquid stream to be divided into several fractional streams, (iv) a static mixer having an inlet, connected to the addition chamber, and an outlet, and (v) an expansion chamber for separating the polymer melt from the residual volatile compounds and from the foaming agent, which chamber is connected to the outlet of the static mixer and is provided with a line for withdrawing the polymer melt and with a line for extracting the residual volatile compounds and the foaming agent.