Isp Investments Inc.

Alan J Carlin

Stephen L Kopolow

Mohammed Tazi

Yoon T Kwak

John N Zamora

A process for making a solution of a copolymer of maleic anhydride (MA) and methyl vinyl ether (MVE) monomers the specific viscosity (SV) of the product being about 2.5-6, preferably 3-5, indicating a weight average molecular weight of substantially above one million, preferably above 1.5 million and a solids content of about 20-45%, preferably 30-40, in isopropyl acetate (IPAc), solvent includes the steps of (a) precharging part of MVE in IPAc into a reactor heated to about 50-90&deg; C., and then (b) feeding (i) a solution of MA in IPAc, (ii) the rest of MVE, at a mole ratio of MA:MVE of 1:&gE;1.5 to 1:<3, preferably 1:2.4, and (iii) a free radical initiator dissolved in IPAc, in an amount of 0.02-0.3%, preferably 0.05-0.2%, based on total monomers, into the reactor over time. Powders of such MA/MVE copolymers are made by removing the solvent from the solution.

Process for making a solution of copolymers of maleic anhydride and alkyl vinyl ether in isopropyl acetate of high specific viscosity and at a high solids level

There is described a process for the production of an ethanol solution of an ethyl or butyl half-ester copolymer of maleic anhydride and a methyl vinyl ether which comprises: (a) copolymerizing the monomers in acetone as solvent by simultaneously feeding molten maleic anhydride, a molar excess of methyl vinyl ether, and a solution of a free radical initiator in acetone, into a reactor precharged with acetone, at about 68.degree.-85.degree. C., preferably 70.degree.-80.degree. C.; (b) esterifying the acetone solution of said copolymer with ethanol or butanol; and then (c) solvent exchanging ethanol for acetone by continuously injecting vapors of ethanol at about 85.degree.-95.degree. C. into said copolymer solution while simultaneously distilling out acetone therefrom at atmospheric pressure.

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Wayne, NJ, United States of America

Alan J Carlin