Abstract: The invention relates to a vented extruder (1) for the devolatilization of a polymer material, encompassing at least one extruder barrel (2) with at least one rotatably driven extruder screw (3) mounted in the extruder barrel (2), and with at least one material feed and with at least one extrudate outlet, and also with at least one vent zone (9). A particular feature of the vented extruder (1) is that the gas output for the gas arising in the vent zone (9) has been provided upstream of the material feed, in relation to the direction of conveying of the polymer material.

Abstract: The invention relates to a vented extruder (1) for the devolatilization of a polymer material. The vented extruder (1) encompasses at least one drive (4), at least one gearbox (5), at least one rotatably driven extruder screw (3), at least one first material feed (6) and at least one extrudate outlet (13). A feature of the vented extruder (1) according to the invention is that the drive, encompassing drive (4) and gearbox (5), has been provided in the region of that end of the extruder screw (3) that is downstream in relation to the direction of conveying of the polymer.

Abstract: An impact resistant provided PMMA moulding material according to DE 195 44 563 is process into a surface-hardened film which is highly glossy, essentially free of gel bodies and can be processed in the “in-mould-film-decoration” method. The melted mass is generated by means of an extruder and fed to the inventive glazing rolls via a flexible lip nozzle, said rolls being configured in order to generate an especially high locking pressure in the roll slit. The smoothing rolls are cambered. The films are used for decorating surfaces of high-value thermoplastic moulded parts.

Abstract: The invention relates to a vented extruder (1) for the devolatilization of a polymer material. The vented extruder (1) encompasses at least one drive (4), at least one gearbox (5), at least one rotatably driven extruder screw (3), at least one first material feed (6) and at least one extrudate outlet (13). A feature of the vented extruder (1) according to the invention is that the drive, encompassing drive (4) and gearbox (5), has been provided in the region of that end of the extruder screw (3) that is downstream in relation to the direction of conveying of the polymer.

Abstract: The invention relates to a vented extruder (1) for the devolatilization of a polymer material, encompassing at least one extruder barrel (2) with at least one rotatably driven extruder screw (3) mounted in the extruder barrel (2), and with at least one material feed and with at least one extrudate outlet, and also with at least one vent zone (9). A particular feature of the vented extruder (1) is that the gas output for the gas arising in the vent zone (9) has been provided upstream of the material feed, in relation to the direction of conveying of the polymer material.

Abstract: Products based on polymethylmethacrylate (PMMA) so resistant to yellowing and so highly transparent that even the edges of plates produced from this material have a neutral colour, i.e. do not display any yellow tone. This effect is obtained by the admixture of 5 to 50 ppm inorganic, reducing phosphorus compounds after polymerisation. This enables the brightener content to be reduced under 10 ppb, and so the end product may also be used in contact with foodstuffs.

Abstract: An impact resistant provided PMMA moulding material according to DE 195 44 563 is process into a surface-hardened film which is highly glossy, essentially free of gel bodies and can be processed in the “in-mould-film-decoration” method. The melted mass is generated by means of an extruder and fed to the inventive glazing rolls via a flexible lip nozzle, saild rolls being configured in order to generate an especially high locking pressure in the roll slit. The smoothing rolls are cambered. The films are used for decorating surfaces of high-value thermoplastic moulded parts.

Abstract: An impact resistant provided PMMA moulding material according to DE 195 44 563 is process into a surface-hardened film which is highly glossy, essentially free of gel bodies and can be processed in the “in-mould-film-decoration” method. The melted mass is generated by means of an extruder and fed to the inventive glazing rolls via a flexible lip nozzle, saild rolls being configured in order to generate an especially high locking pressure in the roll slit. The smoothing rolls are cambered. The films are used for decorating surfaces of high-value thermoplastic moulded parts.

Abstract: The invention relates to a method for dehydrating a two-phase liquid mixture consisting of a thermoplastic synthetic melt phase and an aqueous phase, comprising the following steps: a) coagulation of the two-phase liquid mixture in a first extruder; b) dehydration of the coagulate in a twin screw extruder with a de-watering zone and screws working in an opposite direction; c) separation of constituents by degasifying. The inventive method is characterized in that a single screw extruder or a twin screw extruder with screws working in the same direction is used as a first extruder in step a).

Abstract: The invention concerns a process for producing polymethacrylate moulding compounds, which have high thermal dimensional stability and high stability with respect to thermal decomposition, by the radical polymerization of methylmethacrylate monomers and optionally comonomers in at least two reactors operated successively, ensuring a high degree of blending. The process is characterized in that: a) a first reactor is operated at a temperature of less than 120° C.; and b) a second reactor or further successive reactors is/are operated in a temperature range of more than 130° C. and at most 200° C.

Abstract: A two phase liquid mixture of a thermoplastic synthetic resin melt and an aqueous phase, such as a latex coagulate, is dewatered in a counter-rotating twin screw extruder under a pressure which is greater that the water vapor pressure at the temperature of the melt of the thermoplastic synthetic resin by conveying the melt into partially filled screw channels in the dewatering zone and restricting it in at least one of these screw channels in the entry nip of the twin screws to create a local, narrowly limited, steep pressure gradient and to form a coherent melt cake, and draining the water in liquid form from beneath under gravity upstream from the boundary of the melt cake so that the melt cake does not stand in contact with a coherent aqueous phase.

Abstract: The invention relates to a method for the production of poly(meth) acrylate particles with a particle diameter of 1-15 .mu.m, where the monomers M are polymerized according to the method of batch polymerization, with 20-50 parts by weight of monomer M in a liquid medium LM, consisting of 55-100% by weight of mineral oil, and with the addition of 0.1 to 5 parts by weight of a polymer emulsifier E and 0.05-5 parts by weight of a radical initiator.

Abstract: A plastic melt is treated for a short-time with a liquid treatment agent under pressure, it is divided into defined subquantities, individual subquantities are brought into contact with a treatment agent and combined for a residence time of less than one second with portions of at least one other subquantity, and portions of the mixture thus formed are separated and combined with another subquantity; the steps of dividing and combining the mixture are repeated several times at intervals of less than one second until an intimate mixture of the plastic melt and the treatment agent has formed, allowing the preparation of especially homogeneously structured thermoplastic materials, e.g., poly(methacrylalkylimide) plastics, which are compatible with poly(methyl methacrylate).

Abstract: Homogeneous polymer mixtures of polymethacrylimides consist of a component (A), composed of from 30 to 90 percent by weight of methacrylalkylimide units and from 3.5 to 10 percent by weight of methacrylic acid units, and of a component (B1) or (B2) having from 10 to 50 percent by weight more methacrylalkylimide units than component (A), component (B1) having a degree of imidization of less than 95 percent and containing from 3.5 to 10 percent by weight of methacrylic acid units, and component (B2) having a degree of imidization greater than 95 percent and containing less than 3.5 percent by weight of methacrylic acid units.

Abstract: In a process for imidizing an alkyl methacrylate polymer by reaction with a nitrogen-containing imidizing agent, the formation of carboxyl and anhydride groups is suppressed when a portion of the imidizing agent is added only after the previously added imidizing agent has been reacted at least partially, and particularly when the reaction with the imidizing agent is terminated before the polymer has been completely imidized.

Abstract: An extruded web of synthetic resin having a scratch resistant coating thereon is made by depositing a material adapted to form a scratch resistant coating onto the return run of at least one of the endless belts of a dual belt continuous casting machine, the coating being transferred to the surface of the web as the extruded web is polished and cooled in the casting machine.

Abstract: A scratch resistant coating is applied to one or both surfaces of an extruded thermoplastic synthetic resin web by passing the web through a polishing roll stack wherein at least one of the rolls has thereon a film of a material forming such a scratch resistant coating, the coating being in this way transferred from the roll to the surface of the web.

Abstract: To coat a firm, closed surface having a peelable adhesive masking film thereon, the latter is lifted off the surface at one end and a low viscosity coating composition is poured into the wedge so formed. As the masking film is pulled off further, the wedge moves along the surface, which is thus coated. The coating composition in the wedge is replenished at the rate at which it is consumed.

Abstract: Injection molded parts having a scratch resistant surface are produced by applying a liquid mixture of at least one monomer susceptible of free radical polymerization and having more than one polymerizable double bond and of at least one free radical forming initiator to the forming surface of an injection mold, polymerizing the mixture at least partially, and then injecting a thermoplastic or duroplastic molding composition into the closed mold.

Abstract: The invention relates to opaque synthetic resins containing 1 to 30% by weight of cross-linked beads consisting of a polymer comprised of:(i) 9.9 to 59.9% by weight of at least one radically polymerizable monomer A containing an aromatic residue or nonaromatic monomers A' which contain a halogen;(ii) 90 to 40% by weight of vinyl monomers B which are copolymerizable with these monomers but different from them;(iii) 0.1 to 20% by weight of at least one cross-linking monomer V and(iv) 0 to 10% by weight of a strongly polar monomer Hand where (a) the refractive index of the polymer is higher than that of the polymer matrix and that (b) the average bead size of the beads is in the range of 20 to 50 microns.