Abstract: The invention relates to a process for preparing a polymer polyol, comprising mixing in a reactor vessel, a base polyol, one or more ethylenically unsaturated monomers, a polymerization initiator, optionally a macromer, and optionally a chain transfer agent, and polymerizing the mixture thus obtained at a temperature of 50 to 200° C., wherein after discharging the reactor vessel content, the interior surface of the reactor vessel walls and/or any internals present in the reactor vessel are blasted with round media.

Abstract: The invention relates to a process for the preparation of a polymer polyol which is at most 60 wt. %, which process comprises mixing a base polyol, one or more ethylenically unsaturated monomers, a polymerization initiator, optionally a macromer, and optionally a chain transfer agent, and polymerizing the mixture thus obtained at a temperature of 50 to 200° C., optionally below 120 C, wherein the initiator is of formula R1—C(?O)—O—O—R2 (I) wherein R1 is an alkyl group and R2 is an alkyl group of formula —C(R3)(R4)—C(R5)(R6)(R7) (II) wherein R3 and R4 are the same or different and are an alkyl group, R5, R6 and R7 are the same or different and are a hydrogen atom or an alkyl group.

Abstract: The invention relates to a process for the preparation of a polymer polyol, which process comprises mixing in a reactor vessel a base polyol, one or more ethylenically unsaturated monomers, a polymerization initiator, optionally a macromer, and optionally a chain transfer agent, and polymerizing the mixture thus obtained at a temperature of 50 to 200 ° C., wherein the monomer(s) and initiator are dosed simultaneously to the reactor vessel and wherein during the time period of simultaneously dosing the monomer(s) and initiator the dosing weight ratio of initiator to monomer(s) is increased.

Abstract: The invention relates to a process for preparing a polymer polyol, comprising mixing in a reactor vessel, a base polyol, one or more ethylenically unsaturated monomers, a polymerization initiator, optionally a macromer, and optionally a chain transfer agent, and polymerizing the mixture thus obtained at a temperature of 50 to 200° C., wherein after discharging the reactor vessel content, the interior surface of the reactor vessel walls and/or any internals present in the reactor vessel are blasted with round media.

Abstract: The invention relates to a process for the batch or semi-batch preparation of a polymer polyol, which process comprises mixing a base polyol, one or more ethylenically unsaturated monomers, a polymerization initiator, optionally a macromer, and optionally a chain transfer agent, and polymerizing the mixture thus obtained at a temperature of 50 to 200° C., wherein one or more of the compounds to be mixed are fed while having a temperature that is higher than ambient temperature.