Aqueous secondary dispersions
View Patent ↗The present invention relates to heat and storage stable vinyl polymer polyol secondary dispersions containing A) at least one vinyl polymer resin having functional groups selected from hydroxyl, carboxyl and/or sulfonic acid groups and dispersed in a water/solvent mixture in the presence of a neutralizing agent, and B) at least one amphiphilic polymer built up from a hydrophobic and a hydrophilic segment. The invention also relates to a process for the preparation of the vinyl polymer polyol secondary dispersions by preparing vinyl polymer resin A) by polymerizing a mixture of ethylenically unsaturated monomers a) in the presence of an initiator b) in a water/solvent mixture and adding at least one amphiphilic polymer B), then at least partly neutralizing and dispersing the resulting product, optionally after the addition of a further amount of water.
1. A heat and storage stable vinyl polymer polyol secondary dispersion comprising
A) at least one vinyl polymer resin having hydroxyl groups and also having functional groups comprising a member selected from the group consisting of carboxyl and sulfonic acid groups and dispersed in a water/solvent mixture in the presence of a neutralizing agent, and
B) at least one amphiphilic polymer comprising a block polymer of a vinyl polymer as the hydrophobic segment and either polyethylene oxide or poly(meth)acrylic acid as the hydrophilic segment.
2. The vinyl polymer polyol secondary dispersion of claim 1 wherein the dispersion has a solids content of between 30 and 60 wt. % and at a viscosity 100 to 10,000 mPa·s (23° C., shear gradient D=42 s −1 ).
3. The vinyl polymer polyol secondary dispersion of claim 1 wherein polyethylene oxide is present as the hydrophilic segment.
4. The vinyl polymer polyol secondary dispersion of claim 1 wherein poly(meth)acrylic acid is present as the hydrophilic segment.
5. A process for the preparation of the vinyl polymer polyol secondary dispersion of claim 1 which comprises preparing vinyl polymer resin A) by polymerizing a mixture of ethylenically unsaturated monomers a) in the presence of an initiator b) in a water/solvent mixture with the addition of at least one amphiphilic polymer B), and then at least partly neutralizing and dispersing the product, optionally after adding a further amount of water.
6. The process of claim 5 which comprises preparing vinyl polymer resin A) by polymerizing 30 to 80 wt. % of a mixture of ethylenically unsaturated monomers a) in the presence of 0.5 to 8.0 wt. % of an initiator b) in a mixture of 2 to 20 wt. % of an organic solvent c) and 10 to 50 wt. % of water with the addition of 0.1 to 3.0 wt. % of at least one amphiphilic polymer B), wherein the sum of the components is 100 wt. %.
7. The process of claim 5 which comprises preparing vinyl polymer resin A) by polymerizing 35 to 75 wt. % of a mixture of ethylenically unsaturated monomers a) in the presence of 0.5 to 8.0 wt. % of an initiator b) in a mixture of 5 to 15 wt. % of an organic solvent c) and 15 to 40 wt. % of water with the addition of 0.15 to 2.0 wt. % of at least one amphiphilic polymer B), wherein the sum of the components is 100 wt. %.
8. A water-dilutable coating composition comprising as the binder the vinyl polymer polyol secondary dispersions of claim 1 .
9. The water-dilutable coating composition of claim 8 which additionally comprises a crosslinking agents.
10. A substrate coated or sealed with the coating composition of claim 9 .
11. The substrate of claim 10 wherein the substrate is a metallic surface or a plastic surface.