Moulding Compound for Mouldings with High Weather Resistance

Abstract

A moulding compound comprises a copolymer (I)a), produced by polymerisation of 90-100% by weight methylmethacrylate, styrene and malic acid anhydride, and optionally 0-10% by weight additional monomers which can be copolymerised with methylmethacrylate, a (co)polymer (II)b), produced by polymerisation of 80-100% by weight methylmethacrylate and optionally 0-20% by weight additional monomers which can be copolymerised with methylmethacrylate, and has a solution viscosity in chloroform at 25° C. (ISO 1628 Part 6) of 50 to 55 ml/g, as well as c) optional conventional additives, auxiliary agents and/or fillers. The moulding compound is characterised in that the copolymer (I) has a solution viscosity in chloroform at 25° C. (ISO 1628 Part) of 55 ml/g or less. Also disclosed are mouldings produced by thermoplastic processing of the moulding compound and their uses.

1 . A molding composition, encompassing the following components 
 a) a copolymer (I), polymerized to an extent of from 90 to 100% by weight from methyl methacrylate, styrene, and maleic anhydride, and, optionally, from 0 to 10% by weight of other monomers copolymerizable with methyl methacrylate,    b) a (co)polymer (II), polymerized from from 80 to 100% by weight of methyl methacrylate and, if appropriate, from from 0 to 20% by weight of other monomers copolymerizable with methyl methacrylate, whose solution viscosity in chloroform at 25° C. (ISO 1628-Part 6) is from 50 to 55 ml/g, and    c) optionally conventional additives, auxiliaries, and/or fillers characterized in that    the solution viscosity of the copolymer (I) in chloroform at 25° C. (ISO 1628-Part 6) is less than or equal to 55 ml/g.    
     
     
         2 . The molding composition as claimed in  claim 1 , characterized in that the molding composition or a test specimen produced from the molding composition has the following properties simultaneously: 
 a Vicat softening temperature VST (ISO 306-B50) of at least 109° C.,    a melt index MVR (ISO 1133, 230° C./3.8 kg) of at least from 2.5 to 5.0 cm 3 /10 min.    Xenotest weathering resistance (DIN EN ISO 4893, Part 2) after 10 000 hours characterized via a yellowness index (DIN 6167) of less than or equal to 2.0.    
     
     
         3 . The molding composition as claimed in  claim 1 , characterized in that the increase in the yellowness index (DIN 6167) of a test specimen produced from the molding composition is not more than 1.5 units after Xenotest weathering (DIN EN ISO 4893, Part 2) for 10 000 hours.  
     
     
         4 . The molding composition as claimed in  claim 1 , characterized in that when the Taber 203 scratch hardness of a test specimen produced from the molding composition is determined using an applied force of 3.0 N the value obtained is not more than 3 μm.  
     
     
         5 . The molding composition as claimed in  claim 1 , characterized in that the copolymer (I) and the (co)polymer (II) are present in a ratio of from 95 to 5 to 5 to 95 parts by weight.  
     
     
         6 . The molding composition as claimed in  claim 1 , characterized in that the copolymer (I) has been polymerized from 
 from 50 to 90% by weight of methyl methacrylate,    from 10 to 20% by weight of styrene, and    from 5 to 15% by weight of maleic anhydride.    
     
     
         7 . The molding composition as claimed in  claim 1 , characterized in that the copolymer (II) is a polymer composed of from 95 to 99.5% by weight of methyl methacrylate and from 0.5 to 5% by weight of methyl acrylate.  
     
     
         8 . The molding composition as claimed in  claim 1 , characterized in that the proportion of the conventional additives, auxiliaries, and/or fillers is not more than 10% by weight.  
     
     
         9 . The molding composition as claimed in  claim 1 , characterized in that a lubricant is present as auxiliary.  
     
     
         10 . The molding composition as claimed in  claim 1 , characterized in that the mold-release agent stearyl alcohol is present as auxiliary.  
     
     
         11 . Molded parts, producedentirely or to some extent from a molding composition as claimed in  claim 1  via thermoplastic processing, in particular injection molding or extrusion, or via coextrusion, lamination, or lacquering.  
     
     
         12 . Extruded parts as claimed in  claim 11 , characterized in that the materials are solid sheets, corrugated sheets, panels having cavities, selected from multiple-web sandwich panels, twin-web sandwich panels, triple-web sandwich panels, or quadruple-web sandwich panels, or sandwich panels with lattice geometry, or other sandwich panels.  
     
     
         13 . Molded parts as claimed in  claim 11 , characterized in that the materials are parts of household devices, of communications devices, of equipment for hobbies or for sports, or are bodywork parts, or are parts of bodywork parts in automobile construction, in shipbuilding, or in aircraft construction, lamp covers, instrument covers, tachometer covers, panels, or decorative strips.  
     
     
         14 . Molded parts as claimed in  claim 11 , characterized in that it has at least one coextruded, laminated, or lacquered layer composed of the parts  
     
     
         15 . The method of using the molding composition as claimed in  claim 1  for production of molded parts or of parts thereof via thermoplastic processing, selected from injection molding or extrusion, or via coextrusion, lamination, or lacquering.  
     
     
         16 . The method of using the molding composition as claimed in  claim 1  for the coating of surfaces or for the impregnation of wood.