| Copolymers of alkyl vinyl ether/maleic anhydride, in particular a copolymer of methyl vinyl ether/maleic anhydride, are straight chain and water-soluble polymeric electrolyte compounds. And recently these copolymers have been widely put into use in such industrial fields as additives to a sticking agent (a sticking plaster), an adhesive, a preventive agent for adhesion of detergents, a spray-type fixing agent for hair, a builder for synthetic detergents, a dental material or the like, because the copolymers are excellent in nonpoisonous properties to the human body, stability for a long period of time, tackiness, cohesiveness, a water-holding property, a peeling property and the like. Further, the esterification-products obtained by reacting the maleic anhydride portion in the copolymer with various alcohols are also used in such fields.Up to now,there isn't related researches and reports inland. So the study of the process of producing the copolymer of maleic anhydride and methyl vinyl ether is very important for us.What is discribed herein is a solution feed,slurry precipitation polymerization porcess for making copolymers of maleic anhydride and methyl vinyl ether within a predetermined viscosity range.The process of the experiment is characterized by (i) precharging an organic solvent and maleic anhydride into a reaction vessel, and heating a homogeneous maleic anhydride solution formed;(ii) feeding methyl vinyl ether dissolved in the same solvent into the precharged reactor and polymerizing the monomers in the presence of a free radical initiator, the copolymer product then appears as a pumpable slurry in the reaction medium;(iii) removing the organic solvent used in the reaction by conventional separation means such as filtration, evaporation.Selective solvents used include acetone, ethyl acetate , cyclohexane and a cosolvent system which is a mixture of ethyl acetate and cyclohexane,respectively inthe weight ratio of about 30% to 60% and 40% to 70%. An amount of the organic solvents to be used for polymerization is preferably 1:4 to 1:6 by weight in the ratio of maleic anhydride/organic solvent.The organic free radical-generating initiators included lauroyl peroxide, di-tert-butyl peroxide, tert-Butyl peroxybenzoate and azodiisobutyronitrile. Total amount of the free radical initiators used in the polymerization is preferably in the range of about 0.05% to 0.2% by weight based on maleic anhydride. When the total amount is less than about 0.05% by weight, a reaction time will be long and productivity will undesirably be worsened. When the total amount exceeds about 0.2% by weight, an amount of the polymerization initiators remained in the product will undesirably be increased.The polymerization was carried out at a temperature in the range from 60 degree to 90 degree for 6~11 hours.Experiment results indecate: the optimized condition is using mixture solvent of cyclohexane and ethyl acetate that the weight ratio of cyclohexane is about 40%, using lauroyl peroxide as free radical-generating initiator which the amount to be used is in the range of about 0.05% to 0.2% by weight based on maleic anhydride, preferable polymerization temperature is at 70~80 degree and reaction time lasts 8 hours; the products' yield are over 90% and their specific viscousity are rang from 0.1 to 0.6.The copolymers' structure was characterized by using FT-IR ,H-NMR and 13C-NMR. Analysis indecates that we produced alternate copolymers of maleic anhydride and methyl vinyl ether in the mole ratio of 1:1. The copolymers' specific viscosity were determined by Ubbelohde viscometer and the copolymers' specific vise sities were in the rang of 0.1-0.6.The copolymers' moleculer weight are determined by size exclusive chromato-graphy(SEC) and their Mw are in the rang of 310,000-790,000.At last,we determined the copolymer's Refractive Index Increment: in water ((dn/dc)water=0.2308ml/g) and in THF((dn/dc)THF=0.076ml/g) (25℃) .
|
PDF Full Text Request