PROCESS FOR PREPARING BLOCK COPOLYMER

    公开(公告)号:ZA871595B

    公开(公告)日:1987-08-26

    申请号:ZA871595

    申请日:1987-03-05

    Abstract: Sequential charging of initiator and monomers in a multistage solution polymerization process involving conjugated diene and monovinylaromatic monomers wherein the final charge is a mixture of these monomers results in the production of resinous polymodal linear block copolymers each with a terminal tapered block. A typical 5-stage charge sequence is as follows: Stage 1: (Si); Stage 2: (Si); Stage 3: (B); Stage 4: (Si); Stage 5: (S+B) wherein (Si) is monovinylaromatic monomer and initiator; (B) is conjugated diene monomer and (S+B) is monovinylaromatic monomer and conjugated diene monomer. At each stage, polymerization is allowed to continue until no free monomer is present. The trimodal block copolymer products comprise high, medium and low molecular weight species designated, respectively, as S1-S2-B1-S3-B2->S4; S2-B1-S3-B2->S4; and S3-B2->S4 wherein S1, S2 and S3 represent, respectively, polyvinylaromatic blocks resulting from polymerization of the first, second and third charges of monovinylaromatic monomer (stages 1,2 and 4); B1 represents a polydiene block resulting from polymerization of the first charge of conjugated diene monomer (stage 3); and B2->S4 represents a terminal tapered copolymer block resulting from polymerization of the conjugated diene and monovinylaromatic monomers (stage 5). The subject copolymers can be fabricated into sheets and molded objects possessing little color, a high degree of transparency and excellent impact resistance. These fabricated products do not craze on being impacted.

    PREPARATION OF BLOCK COPOLYMER
    3.
    发明专利

    公开(公告)号:ZA871596B

    公开(公告)日:1987-08-26

    申请号:ZA871596

    申请日:1987-03-05

    Abstract: Sequential charging of initiator and monomers in a multistage solution polymerization process involving conjugated diene and monovinylaromatic monomers wherein the initial and final charges are monovinylaromatic monomer results in the production of polymodal linear block copolymers with terminal resinous blocks. A typical 6-stage charge sequence is as follows: stage 1: (Si); stage 2: (Si); stage 3: (B); stage 4: (Si); stage 5: (B) and stage 6: (S) wherein (Si) is monovinylaromatic monomer and initiator, (B) is conjugated diene monomer and (S) is monovinylaromatic monomer. At each stage, polymerization is allowed to continue until no free monomer is present. The polymodal block copolymer products comprise high, medium and low molecular weight species designated, respectively, as S1-S2-B1-S3-B2-S4; S2-B1-S3-B2-S4; and S3-B2-S4 wherein S1, S2, S3 and S4 represent, respectively, polyvinylaromatic blocks resulting from polymerization of the first, second, third and fourth charges of monovinylaromatic monomer (stages 1,2,4 and 6); B1 represents a polydiene block resulting from polymerization of the first charge of conjugated diene monomer (stage 3); and B2 represents a polydiene block resulting from polymerization of the second charge of conjugated diene monomer (stage 5). The subject copolymers can be fabricated into sheets and molded objects possessing little color, a high degree of transparency and excellent impact resistance. These fabricated products do not craze on being impacted.

Patent Agency Ranking