| 摘要 |
The invention relates to a method for producing molded bodies by injection molding which comprises the following steps a) melting a (meth)acrylate copolymer that is composed of 30 to 80 % by weight of radically polymerized C1 to C4 alkyl esters of acrylic or methacrylic acid and 70 to 20% by weight of (meth)acrylate monomers with a tertiary ammonium groups in the alkyl group. The (meth)acrylate copolymer used is present in a mixture with 1 to 70% by weight of a softener and a desiccating agent in a ratio of 1: 1 to 1: 20 and with 0.05 to 5 % by weight of a mold-release agent. In addition, other conventional additives or adjuvants and optionally a pharmaceutically active substance can be present in the mixture. Before melting, the mixture has a content of low-boiling components with a vapor pressure of at least 1.9 bar at 120 degrees C of more than 0.5 % by weight. In step b) the mixture is degassed in a thermoplastic state at temperatures of at least 120 degrees C, thereby reducing the content of low boiling components with a vapor pressure of at least 1.9 bar at 120 degrees C to not more than 0.5 % by weight. The molten and degassed mixture is c) injected into the mold cavity of an injection mold, the mold cavity having a temperature that is at least 10 degrees C below the glass transition temperature of the (meth)acrylate copolymer. The molten mixture is then cooled off and the molded body obtained is removed from the mold.
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