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US 4,396,741 AGranted
Photometer-controlled anionic polymerization
AssigneeShell Oil Company
InventorArthur R. Bean
Life of this patent
Estimating the term…
Abstract
Random monoalkenyl arene-conjugated diene copolymers are produced by controlling the continuous rate of addition of the conjugated diene monomer to a reactor containing the monoalkenyl arene monomer, organolithium initiator and solvent, the rate being adjusted in response to the photometer measured presence of an active chromophore comprising a lithium ion directly associated with a poly(monoalkenyl arene) carbanion.
Claims11
In the process for preparing anionic random copolymers, which process comprises:
- (a) adding a monoalkenyl arene monomer, minor portion of a conjugated diene monomer and an inert solvent to a reactor;
- (b) adding a polymerizing amount of an organolithium initiator to the resulting solution, therein commencing the polymerization of said monoalkenyl arene monomer;
- and
- (c) continuously adding a conjugated diene monomer to the solution of step (b);
- the improvement comprising controlling the rate of addition of said conjugated diene monomer in step (c) in response to the photometer measured relative presence of an active chromophore comprising a lithium ion directly associated with a poly(monoalkenyl arene) carbanion wherein the desired relative presence has been previously determined to give a desired ratio of monoalkenyl arene monomer units to conjugated diene monomer units in said copolymer.
2 more elements
In the process for preparing anionic random copolymers, which process comprises:
- (a) adding a monoalkenyl arene monomer, minor portion of a conjugated diene monomer and an inert solvent to a reactor;
- (b) adding a polymerizing amount of an organolithium initiator to the resulting solution, therein commencing the polymerization of said monoalkenyl arene monomer;
- and
- (c) continuously adding a conjugated diene monomer to the solution of step (b);
- the improvement comprising:
- (i) continuously sampling the solution of step (c) and determining, by use of a photometer, the relative concentration of active chromophores, said active chromophores comprising a lithium ion directly associated with a poly(monoalkenyl arene) carbanion;
- (ii) producing a first signal representative of said concentration;
- (iii) comparing said first signal to a predetermined level representative of the desired active chromophore concentration to obtain a first control signal, the magnitude of which is related to the difference between said first signal and said predetermined level;
- and
- (iv) adjusting the flow rate of said conjugated diene monomer to said reactor responsive to the magnitude of said control signal until the desired level of said concentration is obtained.
7 more elements
Dependencies are inferred from the claim text.