摘要:
Es wird ein Verfahren zur Herstellung von Lebensmittelverpackungen aus biologisch abbaubarem Schaummaterial, insbesondere von Trays für den Gebrauch als Einweggeschirr, beschrieben. Es wird dabei ein aus einem organischen Celluloseester oder Cellulosemischester, insbesondere Celluloseacetat, bestehendes oder diesen enthaltendes Ausgangsmaterial bereitgestellt, und das Ausgangsmaterial wird zur Feuchtereduzierung einer Vorbehandlung unterzogen. Bis zum Beginn des nachfolgenden Aufschmelzprozesses wird der Feuchtegehalt auf/unter einer festgelegten Grenze gehalten. Das vorbehandelte Ausgangsmaterial wird aufgeschmolzen und schließlich zum Erhalt eines Schaummateriales als Flachmaterial aufgeschäumt. Es folgt dann eine Lagerung des erhaltenen Schaummateriales zum Eindiffundieren eines zweiten Treibmittels und eine Erwärmung, um ein Nachschäumen zu bewirken. Das erwärmte Schaummaterial wird zum Formen der Lebensmittelverpackung tiefgezogen.
摘要:
This invention provides an economical process for extruding a PLA resin into a low density foam with a high closed cell content. Excellent quality, low density foam is produced easily and reproducibly. The PLA resin in the foam has a weight average molecular weight of at least 500,000 and an intrinsic viscosity of at least 1.4 deciliters/gram.
摘要:
A continuous extrusion process for the functionalization of polymers through reactive extrusion. The process uses a continuous extrusion reactor comprising at least two sequential, very closely-coupled, independently driven screw extruders having a total effective length to diameter ratio greater than 60 to 1 and as high as 112 to 1 and providing greatly extended reaction times for efficiently producing a grafted polymer having a high level of functionalization. Drying of the polymer feed is performed in the continuous extrusion reactor. Multiple injections of reactants may be provided. Shear modification of the molecular weight 'of the grafted polymer is performed in the continuous extrusion reactor after the functionalization reactions. A continuous extrusion reactor and a grafted polymer having a high level of functionalization are also disclosed.
摘要:
Foams with low water absorption are provided, along with thermoplastic elastomeric foam materials and methods of forming the same. In some embodiments, the TPE foams have a low water absorption. Microcellular foams are included. Processing conditions (e.g., blowing agent type and content, die geometry, exit melt temperature, among others) may be controlled to produce foams having desirable characteristics, such as low water absorption.
摘要:
The invention provides systems, methods, and articles useful in the production of foams, and, in particular microcellular foams. The systems include a restriction element (35) that reduces the backflow of polymer melt in an extruder while polymeric material is injected into a mold (37) or ejected from a die. The restriction element is positioned upstream of a blowing agent injection port (54) to maintain the solution of polymer and blowing agent in the extruder above a minimum pressure throughout an injection or ejection cycle, and preferably above the critical pressure required for the maintenance of a single-phase solution of polymer and blowing agent. The systems can be used in injection molding, blow molding, or in any other processing techniques that include injection or ejection cycles. In some embodiments, the systems utilize reciprocating screws for injection or ejection. In other embodiments, the systems include an accumulator connected to an outlet of the extruder, in which a plunger moves to inject polymeric material into a mold or eject polymeric material from a die.
摘要:
The invention concerns a device for producing plastic objects by shaping under inert atmosphere, comprising a hopper (1), an endless screw and means for shaping melted polymer. The device for injecting inert gas comprises a gas supply conduit (3), a gas injection surface at the hopper (1) wall and a homogenising chamber co-operating between the hopper (1) wall and the gas supply conduit (3). The end (32) of the gas supply conduit (3) oriented towards the injection surface is closed and has at least a radial orifice (33) for ejecting gas perpendicularly to its flow direction in the conduit.
摘要:
The present invention discloses a generic method for producing void and gas occlusion free materials, as well as apparatuses (30) for batch and continuous production of same. This generic method can be utilized in the production of a wide variety of polymeric compounds and composites and specifically encompasses the two ends of the polymeric spectrum, that is, polymer concretes on the one hand, and fiber-reinforced polymer composites on the other. The composite materials of the present invention are characterized by visual count as being void and gas occlusion free to the level of 1 micron at 1250x magnification. Concomitantly, the invention produces useful polymer concrete materials which exhibit substantially improved integrity for easy machining at high speeds and high dielectric and mechanical strength, as compared with composite materials produced by conventional methods. Thus, one particular application for the materials of the present invention is the class of high voltage electrical insulating materials and insulators (80) where presence of voids, or gas occlusion flaws, may have deleterious effects, leading to their early failure.
摘要:
A system for halogenating olefinic-based elastomer, the system comprising a first extruder, a first kneader vessel downstream of said first extruder and in fluid communication with said first extruder, a second extruder downstream of said first kneader vessel and in fluid communication with said first kneader vessel, a second kneader vessel downstream of said second extruder and in fluid communication with said second extruder; and a third extruder downstream of said second kneader vessel and in fluid communication with said second kneader vessel.
摘要:
A method for improving the throughput of solid-state shear pulverization and solid-state melt-extrusion devices may include the addition of a heat absorbing material with a mixture of polymeric materials in an extruder. The extruder may include one or more extrusion screws. One or more portions of the one or more extrusion screws, one or more barrel sections, and/or one or more extruder work zones may be temperature controlled to maintain a temperature of the polymeric mixture in contact therewith at or below the liquefication temperature of the polymeric materials. The liquefication temperature may be a melting point of a semi-crystalline polymer or a glass transition temperature of an amorphous polymer.