Flexible polyamide composition

Abstract

The invention relates to a flexible polyamide composition containing at least 50 parts by weight of non-cross-linked rubber per 50 parts by weight of polyamide and the production thereof. The polyamide has a molecular weight such that the melt viscosity at the processing temperature is at most 300 Pa.s, preferably at most 200 Pa.s. The rubber's Mooney viscosity is at least 40, most preferable is a rubber with a Mooney viscosity of at least 60. The rubber has been functionalized. Preferably a combination of a functionalized and a non-functionalized rubber is used. The rubber particles in the polyamide matrix have a particle size of at most 5¼ m, preferably at most 3¼ m.

1 . Process for preparing a flexible polyamide composition containing at least 50 parts by weight of non-crosslinked rubber per 50 parts by weight of polyamide by mixing 
 A. 30-50 parts by weight of at least one polyamide and    B. 70-50 parts by weight of a rubber composition containing at least one functionalized rubber with one another in the melt phase with A+B=100 parts by weight, characterized in that the polyamide has a molecular weight such that the melt viscosity, measured at low shear, at the temperature at which the polyamide and the rubber are mixed in the melt, is lower than 300 Pa.s and the rubber has a Mooney viscosity, ML(1+4), 125° C., measured according to ISO 289-1985-(E), of at least 40.    
     
     
         2 . Process according to  claim 1 , characterized in that the polyamide has a molecular weight such that the melt viscosity is lower than 200 Pa.s.  
     
     
         3 . Process according to  claim 2 , characterized in that the melt viscosity is lower than 100 Pa.s.  
     
     
         4 . Process according to any one of claims  1 - 3 , characterized in that the rubber's Mooney viscosity is at least 50.  
     
     
         5 . Process according to any one of claims  1 - 4 , characterized in that the mixing in the melt is carried out in an extruder.  
     
     
         6 . Process according to any one of claims  1 - 5 , characterized in that rubber composition B is a combination of at least one functionalized and at least one non-functionalized rubber.  
     
     
         7 . Process according to any one of claims  1 - 6 , characterized in that the functionalized rubber has been functionalized with acid groups.  
     
     
         8 . Process according to  claim 6 , characterized in that the rubber is chosen from the group comprising ethylene-α-olefin co- and terpolymers.  
     
     
         9 . Process according to  claim 6 , characterized in that the functionalized rubber is chosen from an ethylene-propylene copolymer modified with maleic acid and a styrene-butadiene block copolymer functionalized with maleic acid anhydride.  
     
     
         10 . Process according to  claim 6 , characterized in that the weight ratio of the functionalized and non-functionalized rubbers is between 10 and 0.1.  
     
     
         11 . Process according to claim  03 , characterized in that the weight ratio is between 0.9 and 0.1.  
     
     
         12 . Flexible polyamide composition comprising 
 A: 30-50 parts by weight of at least one polyamide    B: 70-50 parts by weight of at least one non-crosslinked rubber, with A+B=100 parts by weight, characterized in that the rubber phase is dispersed as discrete particles in the polyamide as the continuous phase.    
     
     
         13 . Flexible polyamide composition according to  claim 12 , characterized in that the average particle size of the dispersed rubber is smaller than 5 μm.  
     
     
         14 . Flexible polyamide composition according to  claim 13 , characterized in that phase B consists of (b1) at least one non-functionalized rubber and (b2) at least one functionalized rubber.  
     
     
         15 . Flexible polyamide composition according to  claim 14 , characterized in that in the dispersed rubber particles (b1) constitutes the nucleus and (b2) surrounds it as a shell.  
     
     
         16 . Process according to any one of claims  1 - 11 , characterized in that the polyamide contains a plasticizer.  
     
     
         17 . Flexible polyamide composition according to any one of claims  12 - 15 , characterized in that the polyamide contains a plasticizer.  
     
     
         18 . Process according to any one of claims  1 - 11  and  16 , characterized in that the composition is subjected to solid-phase after-condensation.  
     
     
         19 . Moulded article entirely or partly consisting of the composition according to any one of claims  12 - 15  or  17 .  
     
     
         20 . Moulded article according to  claim 19  obtained through sequential extrusion or coextrusion of the composition according to any one of claims  12 - 15  or  17  with glass-fibre-reinforced polyamide.