Weatherable resinous composition having improved opacity and impact strength

A thermoplastic molding composition comprising

• (1) 15 to 50 percent of a grafted rubber (GR), and
• (2) 85 to 50 percent of a copolymer matrix (MX),
• the percents for both occurrences being relative to the total weight of (GR) and (MX),
• wherein grafted rubber (GR) includes a substrate (S) containing a crosslinked elastomer selected from the group consisting of polyalkyl acrylate and hydrogenated polydiene, a first grafted phase (P1) and a subsequent grafted phase (P2) where first grafted phase and subsequent grafted phase are sequentially grafted to said substrate and where weight ratio (S)/(P1+P2) is in the range of 60/40 to 90/10, and wherein said first grafted phase (P1) contains a copolymer consisting of at least one monomer selected from a group (3GP) consisting of styrene, α-methyl styrene, ring-halogenated styrene and ring-alkylated styrene, and at least one monomer selected from a group (4GP) consisting of (meth)acrylonitrile and methylmethacrylate, where polymerized monomer of said (3GP) is present in an amount of 80 to 90 percent relative to the weight of said (P1) and the polymerized monomer of said (4GP) is present in an amount of 10 to 20 percent relative to the weight of said (P1), and where said (P2) contains a copolymer of at least one monomer selected from a group (5GP) consisting of styrene, α-methyl styrene, ring-halogenated styrene and ring-alkylated styrene, and at least one monomer selected from a group (6GP) consisting of (meth)acrylonitrile and methylmethacrylate, where polymerized monomer of said (5GP) is present in an amount of about 70 to 75 percent relative to the weight of said subsequent grafted phase (P2) and the polymerized monomer of said (6GP) is present in an amount of about 25 to 30 percent relative to the weight of (P2), and wherein weight ratio (P1)/(P2) is 1/4 to 4/1, said first grafted phase (P1) and said subsequent grafted phase (P2) being chemically different one from the other, said grafted rubber present in particulate form having a weight average particle size of about 0.1 to 1.0 microns, said copolymeric matrix contains at least one polymerized monomer selected from the group (MX1) consisting of styrene, α-methyl styrene, ring-halogenated styrene and ring-alkylated styrene and at least one polymerized monomer selected from the group (MX2) consisting of (meth)acrylonitrile and methylmethacrylate, where weight ratio (MX1)/(MX2) is in the range of 80/20 to about 65/35.