Polycarbonate compositions, articles, and method of manufacture

Abstract

A thermoplastic composition comprises about 10 to about 85 wt. % of a polycarbonate resin; about 1 to about 40 wt. % of an impact modifier composition; and about 1 to about 50 wt. % of an impact-modified alkyl(meth)acrylate polymer; each based on the total combined weight of the thermoplastic composition, exclusive of any filler. The compositions have improved weld line strength, and are useful in the manufacture of molded parts, especially for electronic devices.

1 . A thermoplastic composition, comprising:
 about 10 to about 85 wt. % of a polycarbonate resin;   about 1 to about 40 wt. % of an impact modifier composition; and   about 1 to about 50 wt. % of an impact-modified alkyl(meth)acrylate polymer;   each based on the total combined weight of the thermoplastic composition, exclusive of any filler.   
     
     
         2 . The composition of  claim 1 , comprising about 20 to about 80 wt. % of a polycarbonate resin; about 2.5 to about 35 wt. % of an impact modifier composition; and about 5 to about 35 wt. % of an impact-modified alkyl(meth)acrylate polymer; each based on the total combined weight of the thermoplastic composition, exclusive of any filler. 
     
     
         3 . The composition of  claim 1 , wherein a sample bar of the thermoplastic composition molded in a double gated mold and having a thickness of 2 mm (+10%) has a tensile Charpy of greater than about 100 kJ/m 2  measured in accordance with DIN 53448-B. 
     
     
         4 . The composition of  claim 1 , wherein a sample bar of the thermoplastic composition molded in a double gated molded and having a thickness of 2 mm (±10%) has a delta tensile stress at yield of less than about 6 MPa relative to a sample bar of the same composition molded in a single gated mold and having a thickness of 2 mm (±10%), when measured in accordance with ISO 527. 
     
     
         5 . The composition of  claim 1 , wherein a sample bar of the thermoplastic composition molded in a double gated mold and having a thickness of 2 mm (±10%) has a tensile elongation at break of greater than about 2.5% measured in accordance with ISO 527 at room temperature. 
     
     
         6 . The composition of  claim 1 , wherein a sample bar of the thermoplastic composition molded in a double gated mold and having a thickness of 4 mm (±10%) has an Unnotched Izod Impact of greater than about 7 kJ/m 2  measured in accordance with ISO 180/1A. 
     
     
         7 . The composition of  claim 1 , wherein a sample bar of the thermoplastic composition molded in a double gated mold and having a thickness of 2 mm (±10%) has a tensile elongation at break of greater than about 2.5% measured on a 2 mm (±10%) bar molded in a double-gated mold in accordance with ISO 527 at room temperature. 
     
     
         8 . The composition of  claim 1 , wherein a sample bar of the thermoplastic composition molded in a single gated mold and having a thickness of 4 mm (±10%) has a Notched Izod Impact of greater than about 20 kJ/m 2 , measured at 0° C. in accordance with ISO 180/1A. 
     
     
         9 . The composition of  claim 1 , wherein a sample bar of the thermoplastic composition molded in a single gated mold and having a thickness of 4 mm (±10%) has Notched Izod Impact of greater than about 15 kJ/m 2 , measured at −30° C. in accordance with ISO 180/1A. 
     
     
         10 . The composition of  claim 1 , further comprising a polysiloxane-polycarbonate copolymer, wherein the polysiloxane-polycarbonate copolymer comprises:
 aromatic carbonate units of formula (1):   
       
         
           
           
               
               
           
         
       
       wherein at least about 60 percent of the total number of R 1  groups are aromatic organic radicals and the balance thereof are aliphatic, alicyclic, or aromatic radicals; and
 polydiorganosiloxane units of formula (7) 
 
       
         
           
           
               
               
           
         
         wherein 
         each R is independently a C 1-13  monovalent organic radical; 
         D has an average value of 2 to about 1000, 
         each R 2  is independently a divalent C 2 -C 8  aliphatic group; 
         each M is independently a halogen, cyano, nitro, C 1 -C 8  alkylthio, C 1 -C 8  alkyl, C 1 -C 8  alkoxy, C 2 -C 8  alkenyl, C 2 -C 8  alkenyloxy group, C 3 -C 8  cycloalkyl, C 3 -C 8  cycloalkoxy, C 6 -C 10  aryl, C 6 -C 10  aryloxy, C 7 -C 12  aralkyl, C 7 -C 12  aralkoxy, C 7 -C 12  alkaryl, or C 7 -C 12  alkaryloxy; and 
         each n is independently 0, 1, 2, 3, or 4. 
       
     
     
         11 . The composition of  claim 1 , wherein the impact modifier comprises an elastomeric phase comprising a butadiene rubber, an isoprene rubber, an ethylene-propylene rubber, an ethylene-propylene-diene monomer rubber, an ethylene-vinyl acetate rubbers, a silicone rubber, an elastomeric rubber derived from a C 4-9  alkyl (meth)acrylate; an elastomeric copolymer of a C 1-9  alkyl(meth)acrylate with butadiene and/or styrene, or a combination comprising at least one of the foregoing elastomers, together with a rigid copolymer phase derived from the copolymerization of a monomer of formula (13): 
       
         
           
           
               
               
           
         
       
       wherein each X c  is independently hydrogen, C 1 -C 12  alkyl, C 3 -C 12  cycloalkyl, C 6 -C 12  aryl, C 7 -C 12  aralkyl, C 7 -C 12  alkaryl, C 1 -C 12  alkoxy, C 3 -C 12  cycloalkoxy, C 6 -C 12  aryloxy, chloro, bromo, or hydroxy, and R is hydrogen, C 1 -C 5  alkyl, bromo, or chloro, with a monomer of the generic formula (14): 
       
         
           
           
               
               
           
         
       
       wherein R is hydrogen, C 1 -C 5  alkyl, bromo, or chloro, and X c  is cyano, C 1 -C 12  alkoxycarbonyl, C 1 -C 12  aryloxycarbonyl, or hydroxycarbonyl. 
     
     
         12 . The composition of  claim 1  wherein the impact modifier is ABS, MBS, AES, MABS, ASA, or a combination comprising at least one of the foregoing impact modifiers. 
     
     
         13 . The composition of  claim 1 , wherein the impact-modified poly(alkyl (meth)acrylate) comprises PMMA. 
     
     
         14 . The composition of  claim 1 , wherein the impact-modified poly(alkyl (meth)acrylate) has a notched Izod of greater than about 20 J/m measured in accordance with ASTM D-256 at room temperature. 
     
     
         15 . The composition of  claim 1 , wherein the impact-modified poly(alkyl (meth)acrylate) comprises about 0.1 to about 5 wt. % of an impact modifying component. 
     
     
         16 . The composition of  claim 15 , wherein the impact modifying component is formed from a copolymerizable monovinylaromatic monomer, a copolymerizable monovinylic monomer that is not C 1 -C 2  alkyl(meth)acrylate), or a mixture comprising at least one of the foregoing monomers. 
     
     
         17 . The composition of  claim 16 , wherein the impact-modified poly(alkyl (meth)acrylate) comprises units derived from methyl methacrylate, ethyl acrylate, and styrene. 
     
     
         18 . The composition of  claim 1 , further comprising a filler, a reinforcing agent, a pigment, or a combination comprising at least one of the foregoing additives. 
     
     
         19 . An article comprising the composition of  claim 1 . 
     
     
         20 . A thermoplastic composition, comprising:
 about 20 to about 80 wt. % of a polycarbonate resin;   about 2.5 to about 35 wt. % of an impact modifier composition; and   about 5 to about 35 wt. % of an impact-modified alkyl(meth)acrylate polymer; each based on the total combined weight of the thermoplastic composition, exclusive of any filler, and   wherein a sample bar of the thermoplastic composition molded in a double gated mold and having a thickness of 2 mm (+10%) has a tensile Charpy of greater than about 100 kJ/m 2  measured in accordance with DIN 53448-B.   
     
     
         21 . The composition of  claim 20 , wherein the impact-modified poly(alkyl (meth)acrylate) comprises PMMA. 
     
     
         22 . An article comprising the composition of  claim 20 . 
     
     
         23 . A thermoplastic composition comprising:
 about 20 to about 80 wt. % of a polycarbonate resin;   about 2.5 to about 35 wt. % of an impact modifier composition, wherein the impact modifier is ABS, MBS, AES, MABS, ASA, or a combination comprising at least one of the foregoing impact modifiers; and   about 5 to about 35 wt. % of an impact-modified alkyl(meth)acrylate polymer, wherein the impact-modified poly(alkyl(meth)acrylate) comprises PMMA; each based on the total combined weight of the thermoplastic composition, exclusive of any filler, and   wherein a sample bar of the thermoplastic composition molded in a double gated mold and having a thickness of 2 mm (±10%) has a tensile Charpy of greater than about 100 kJ/m 2  measured in accordance with DIN 53448-B.