Injection molding method for neutral and acidic-group containing methacrylate copolymers

摘要

The present invention relates to a method for producing a molded article by injection molding comprising the steps of: 40 to 100% by weight of radically polymerized C ₁ to C ₄ -alkyl esters of acrylic acid or methacrylic acid and anionic moieties to alkyl radicals (A) melting a mixture prepared from a (meth) acrylate copolymer consisting of 0 to 60% by weight of (meth) acrylate monomer having. The (meth) acrylate copolymer comprises 0.1 to 3% by weight of the release agent compound (b). Optionally, 0 to 50 wt% desiccant (c), 0 to 30 wt% plasticizer (d), 0 to 100 wt% additive or adjuvant (e), 0 to 100 wt% pharmaceutical formulation (f), And 0-20% by weight of another polymer or copolymer (g) may be included in the mixture. The amounts shown in components (b) to (g) relate to the (meth) acrylate copolymer (a), and before melting the mixture contains at least 0.5% by weight of a low boiling point component having a vapor pressure of at least 1.9 bar at 120 ° C. The process of the present invention further comprises devolatilizing the mixture in the thermoplastic state at a temperature of at least 120 ° C., thereby reducing the content of low boiling point components with a vapor pressure of at least 1.9 bar at 120 ° C. (B), And (C) injecting the molten and devolatilized mixture into the mold steel of the injection mold apparatus in which the temperature of the mold steel is at least 10 ° C. lower than the glass transition temperature of the (meth) acrylate copolymer. The molten mixture is then cooled, and then the molded body is separated from the mold.