Impact-resistant polyoxymethylene moulding compounds, use thereof and moulding compounds produced therefrom

Abstract

The present invention relates to a polyoxymethylene molding composition comprising: (A) from 0.1 to 5.0% by weight of a compatibilizer, (B) from 5 to 50% by weight of an impact modifier, (C) the remainder to 100% by weight of a polyoxymethylene. The molding compositions of the invention have substantially improved mechanical properties, in particular impact resistance.

1 . A polyoxymethylene molding composition comprising 
 (A) from 0.1 to 5.0% by weight of a compatibilizer,    (B) from 5 to 50% by weight of an impact modifier,    (C) the remainder to 100% by weight of a polyoxymethylene.    
   
   
       2 . The polyoxymethylene molding composition comprising 
 (A) from 0.2 to 2% by weight of a compatibilizer,    (B) from 5 to 40% by weight of an impact modifier,    (C) the remainder to 100% by weight of a polyoxymethylene.    
   
   
       3 . The polyoxymethylene molding composition comprising 
 (A) from 0.3 to 0.6% by weight of a compatibilizer,    (B) from 7 to 30% by weight of an impact modifier,    (C) the remainder to 100% by weight of a polyoxymethylene.    
   
   
       4 . The polyoxymethylene molding composition as claimed in  claim 1 , where the compatibilizer contains many underlying units of the following formulae:  
     
       
         
         
             
             
         
       
     
     and, where appropriate,  
     
       
         
         
             
             
         
       
     
     where R and R 2  are a hydrogen atom or an alkyl group having 1 or 2 carbon atoms,  
     
       
         
         
             
             
         
       
     
     and where X is CH 3  or  
     
       
         
         
             
             
         
       
     
     and at least one X is  
     
       
         
         
             
             
         
       
     
     and where 
 a is a number from 1 to 10,  
 b is 0 or 1,  
 c is a number from 0 to 10,  
 l is a number from 0 to 10,  
 R 3 , R 5  are a hydrogen atom or a methyl group,  
 R 4  is a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms,  
 m is 1 or 2,  
 n is 0 or 1 or 2,  
 x is an integer from 0 to 10,  
 Y is H or  
                     
 where  
 R 6 , R 7  are identical or different and are an alkyl group having from 1 to 4 carbon atoms,  
 R 8  is an alkyl group having from 1 to 12 carbon atoms, phenyl, alkylphenyl or cycloalkyl having from 3 to 12 carbon atoms  
                     
 where the underlying units of the formulae (Ia), (Iia), (IIIa), (Iva) and (Va) may have bonding to underlying units of the formulae (I), (II), (III), (IV), or (V), and the compatibilizer comprises  
 from 29 to 70% by weight of underlying unit of the formula (I)  
 from 0.5 to 30% by weight of underlying unit of the formula (II)  
 from 10 to 70% by weight of underlying unit of the formula (III)  
 and from 0 to 10% by weight of underlying units of the formula (IV) and/or (V).  
 
   
   
       5 . The polyoxymethylene molding composition as claimed in  claim 1 , wherein the compatibilizer has a molecular weight of from 5000 to 10 8 .  
   
   
       6 . The polyoxymethylene molding composition as claimed  claim 1 , wherein the compatibilizer has a molecular weight of from 10 4  to 10 6 .  
   
   
       7 . The polyoxymethylene molding composition as claimed in  claim 1 , where component (B) comprises a polyurethane or a two-phase mixture made from polybutadiene and styrene-acrylonitrile (ABS), or comprises modified polysiloxanes and, respectively, silicone rubbers, or graft copolymers made from an elastomeric, single-phase core based on polydiene and from a hard outer graft layer, with fine distribution.  
   
   
       8 . The polyoxymethylene molding composition as claimed in  claim 1 , where component (B) comprises graft polymers made from an elastomeric, single-phase core based on polydiene and a hard outer graft layer, the outer layer of the particles having one or two subshells, where in the case of particles having one subshell the shell is composed of poly(meth)acrylate and poly(meth)acrylonitrile, and in the case of particles having two such shells the inner subshell is composed of crosslinked polystyrene and the outer subshell is composed of crosslinked polymethacrylate.  
   
   
       9 . The polyoxymethylene molding composition as claimed in  claim 1 , where component (C), the polyoxymethylene, has been prepared using trifluoromethanesulfonic acid or boron trifluoride as initiator.  
   
   
       10 . The use of the thermoplastic molding composition as claimed in  claim 1  for producing moldings or films.  
   
   
       11 . A molding produced from a thermoplastic molding composition as claimed in  claim 1.