Adhesion to PV Latex Coating

Manufacturer: In a particular application we are using a lightly filled Prevul Latex coating. A second coating based on a blend of synthetic Latices(Acrylic & CSBR) is applied to the first coat after drying. We are finding the adhesion to the Prevul is not very strong, and seems to get weaker after some time. We tried adhesion promoters with limited success. We are seeking advice how to achieve a strong intercoat adhesion, or what type of synthetic polymers form strong bonds with the dried and cured Prevul film.

John Woon (Senior Latex Consultant): This could probably be due to the difference in polarity between NR latex (PV) and acrylic/CSBR. I suggest you try adding a small level of either acrylic or CSBR into the PV before use bearing in mind that there could be some destabilisation of the PV as a result. If this happens, you should pre-stabilise the PV with some surfactants such as the non-ionic surfactants before blending with the synthetic latices.

Do not allow the PV to be too dry before applying the synthetic latex otherwise you would get poor bonding (adhesion).

For other details, please see my separate report on "Adhesion and Cohesion" especially Page 10 to Page 13.

Hope this helps. Do let me know the outcome.