| 摘要 |
Polymers or copolymers of olefinically unsaturated organic compounds are manufactured in aqueous dispersion with the use of a redox system comprising an inorganic or organic per-compound and as reducing agent hydrogen and/or a compound that splits off hydrogen, the reaction being carried out in the presence of a colloidally dispersed noble metal of Group VIII (i.e. Pt, Pd, Rh, Ru, Os and Ir). Any olefinically unsaturated compound capable of polymerizing alone or in admixture with one another with the use of a free radical-forming agent can be used, e.g. olefines; vinyl or vinylidene halides; vinyl esters; acrylic compounds; unsaturated mono- or di-carboxylic acids or anhydrides thereof or mono- or di-esters of these acids; unsaturated aldehydes; allyl esters; N-vinyl-compounds; vinyl sulphonic acids or salts thereof and dienes. Inorganic or organic per-compounds customarily employed in redox systems are used, the amount preferably being from 0.001 to 2% by weight of per-compound calculated on the monomer or monomers used. Reducing agents mentioned are sodium, lithium, calcium, boron and aluminium hydrides, lithium borohydride, sodium borohydride, and lithium-aluminium hydride. The partial pressure of the hydrogen used as reducing agent is preferably within the range 0.01 to 100 atmospheres absolute. The noble metals are preferably used in the form of aqueous sols which may be stabilized by adding protective colloids. The proportion of noble metal is preferably 0.000001 to 0.1% by weight calculated on the weight of monomers used. The ratio by weight of water to monomer may be within the range 1:2 to 10:1. As dispersing agents there may be used any emulsifying agents or protective colloids normally used in the polymerization of unsaturated organic compounds in aqueous dispersion; they may be used singly or as mixtures, the amount used being in the range 0.1 to 2% by weight of the monomers. |
