Abstract: The invention relates to polymer emulsions of poly(meth)acrylic acid esters and olefin copolymers suitable for improvement of the viscosity index, for use as oil additives.The polymer emulsion is formed of a continuous phase of poly(meth)acrylic acid esters and d-oligomers where the esters and oligomers have a bimodal molecular-weight distribution, a stabilizing agent (a graft or block polymerizate of an olefin copolymerizate and methacrylic acid esters), and a disperse phase of olefin copolymerizates distributed in the continuous phase.

Abstract: Synthetic oils comprising 5-100 percent by weight of an oligomer ofA) 0-75 wt. % of at least one 1-alkene,B) 20-100 wt. % of at least one (meth)acrylic acid ester of the formula ##STR1## wherein R is hydrogen or methyl and R.sub.1 is optionally branched alkyl or cycloalkyl, andC) 0-65 wt. % of a (meth)acrylic acid ester of the formula ##STR2## wherein R' is hydrogen or methyl and R.sub.2 is alkyl substituted with at least one hydroxy group or is ##STR3## wherein R.sub.3 and R.sub.4 are hydrogen or methyl, R.sub.5 is hydrogen or optionally branched alkyl, but if n is 1, then R.sub.5 is exclusively optionally branched alkyl.

Abstract: The invention relates to the stabilization of the activity and/or the reactivation of molybdoheteropoly acid catalysts in vapor-phase oxidations, such as the oxidehydrogenation of isobutyric acid or its lower esters to methacrylic acid or its lower esters, by means of an oxidizing treatment of the catalyst in which compounds of catalyst constituents are added, at temperatures ranging from 200.degree. to 400.degree. C., with an oxygen-containing gas.The inventive activation measures can be carried out either during the catalytic vapor-phase reaction, such as oxihydrogenation in particular, or intermittently to alternate therewith, and optionally also physically separated in part from each other.