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Block copolymers of monovinylarenes and conjugated dienes and preparation thereof
| Details |
Inventors: Moczygemba, George A.; Nash, Larry L.; Trepka, William J.; DePorter, Craig D.; Stacy, Nathan E.; Farrar, Ralph C.; Selman, Charles M.;
Assignee: Phillips Petroleum Company (Bartlesville, OK)
Primary Examiner: Warzel; Mark L.
Assistant Examiner:
Attorney, Agent or Firm: Corvin; Carl D.
A method for preparing resinous polymodal monovinylarene-conjugated diene block copolymers and polymers produced thereby are provided. The method comprises sequentially contacting under polymerization conditions: (a) a monovinylarene monomer and initiator; (b) initiator and a monovinylarene monomer; (c) a sequence of at least two charges selected from the group consisting of (i) initiator and a monovtnylarene monomer, (ii) a mixture of monovtnylarene monomer and conjugated diene monomor, (iii) a conjugated diene monomer, (iv) a monovinylarene monomer; (d) a coupling agent; wherein the sequence of at least two charges in step (c) can be made in any order. In a preferred embodiment, at least three Initiator charges are provided. In another preferred embodiment, at least three monovinylarene charges precede the first charge containing conjugated diene. In another preferred embodiment, at least four monovinylarene charges precede the first charge containing conjugated diene. |
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DETAILED DESCRIPTION OF THE INVENTION This is a continuation-in-part of application Ser.
No.
08/130,039 filed Sep.
30, 1993 the disclosure of which is herein incorporated by reference.
We have discovered novel monovinylarene-conjugated diene block copolymers which can be used neat as a substitute for blends of other monovinylarene-conjugated diene copolymers with polystyrene to produce resins which can be formed into high styrene content articles with low unreacted styrene monomer content and advantageous impact properties and/or ductility.
The polymers of this invention are characterized as resinous non-rubbery block copolymers of at least one conjugated diene with at least one monovinylarene and are prepared so that, when the choice of coupling agent permits at least a portion of the final product is of a branched, coupled character.
The polymers prepared according to this invention contain from about 55 to about 95, preferably from about 60 to about 95, more preferably from about 65 to about 95, weight percent copolymerized monovinylarene monomer based on the weight of total monomers employed.
Correspondingly, the inventive copolymers contain from about 45 to about 5, preferably from about 40 to about 5, and more preferably from about 35 to about 5 weight percent copolymerized conjugated diene monomer based on the total weight of monomers in the copolymer.
Presently preferred when the invention copolymers are used as replacements for blends of other monovinylarene-conjugated diene copolymers with polystyrene, the polymers of this invention contain from about 80 to about 95, more preferably from 80 to 90 weight percent copolymerized monovinylarene monomer based on the weight of total monomers employed.
Correspondingly, the inventive copolymers contain from about 20 to about 5, more preferably from about 20 to about 10 weight percent copolymerized conjugated diene monomer based on the total weight of monomers in the copolymer.
Generally, the first monovinylarene monomer charge contains monovinylarene monomer in the amount in the range of from about 30 weight percent to about 50 weight percent based on the total weight of the final block copolymer
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Adhesives and Rubbers 
