GB820469A - Improvements in or relating to poly (vinyl ethers) and preparation thereof - Google Patents

Abstract

Vinyl ethers are polymerized using as catalyst a mixture of a compound of a metal of Group IVa or Va with an organometallic compound of an alkali or alkaline earth metal, zinc or aluminium. The process yields polyvinyl methyl ethers or polyvinyl ethyl ethers which have a high degree of crystallinity and are insoluble in cold water, methanol, or ethanol. Any vinyl ether or mixture of vinyl ethers may be polymerized according to the invention. A list of vinyl ethers is given in the Specification. The process may be batch or continuous and may take place in an inert liquid, e.g. hexane, heptane, cyclohexane, benzene, toluene, xylene, ethyl chloride, methyl chloride, methylene chloride, ethylene chloride, chlorobenzene, diethyl ether, dioxane or tetrahydrofuran. Temperatures may vary from - 80 DEG to 150 DEG C., and pressures may be atmospheric or sub- or super-atmospheric. Suitable Group IVa or Va metal compounds are those of titanium, zirconium, hafnium, thorium, vanadium, niobium, or tantalum. A list of suitable compounds is given in the Specification. The compound may react p with the organometallic compound by reduction to a lower valency state. The resulting complex can be used alone or in admixture with additional organometallic compound. A list of suitable organometallic compounds is given in the Specification. It includes substances such as butyl lithium, dimethyl magnesium, phenyl magnesium bromide, triethyl aluminium, dipropyl aluminium fluoride, ethyl aluminium dimethoxide, and sodium aluminium triethyl chloride. If the catalysts are insoluble in the reaction medium they should be finely divided. If desired a complexing agent for the organometallic compound, e.g. an ether, tertiary amine, ester, ketone or nitroaromatic such as diethyl ether, tetrahydrofuran, triethylamine or ethyl acetate may be included in the reaction mixture. Complexing agents such as diethyl ether or tetrahydrofuran may form the major component of the reaction medium. Hydrogen may be added to the polymerization system to control or reduce the molecular weight of the polymer. In the examples: (1) vinyl methyl ether was polymerized in heptane in presence of a mixture of vanadium trichloride and triisobutyl aluminium; (2) the vanadium trichloride was first reacted with triethylaluminium. In each case polymerization was stopped by addition of alcohol, and the polymers washed with ethanol and purified by dissolving in cyclohexanone containing phenyl-b -naphthylamine precipitating by addition of heptane also containing phenyl-b -naphthylamine, filtering and drying in vacuo. Example (3) uses diethyl ether as reaction medium, and Example 4 tetrahydrofuran. In Example 5 the catalyst was a mixture of triisobutylaluminium with tantalum pentachloride; in Example 6 a mixture of triisobutylaluminium with vanadium pentoxide; and in Example 7 a mixture of triisobutylaluminium with the reaction product of triethylaluminium and titanium chloride. Example 8 uses a mixture of triisobutylaluminium with titanium trichloride. In Examples 9-16 the reaction medium was n-heptane and the catalyst a mixture of triisobutylaluminium with the reaction product of triethylaluminium and vanadium tetrachloride. The following ethers were polymerized: (9) vinyl ethyl ether; (10) vinyl methyl ether; (11) vinyl n-butyl ether; (12) vinyl iso-butyl ether; (13) vinyl stearyl ether; (14) vinyl tert.-butyl ether; (15) vinyl iso - bornyl ether; (16) vinyl - a - terpinyl ether. Example 17 is similar to 9 to 16 but uses toluene as the reaction medium and vinyl benzyl ether as the monomer. Examples 18, 19 use n-heptane as reaction medium, a mixture of monoisobutylaluminium dimethoxide and titanium trichloride as catalyst and vinyl n-propyl ether and vinyl iso-propyl ether as the respective monomers.