Multistage emulsion polymer and coatings formed therefrom
A multi-stage aqueous emulsion polymer, an aqueous coating composition including the emulsion polymer, and a method for providing a coating including the emulsion polymer are provided. The multistage emulsion polymer includes from 10% to 30% by wt., based on the wt. of the multistage emulsion polymer, of a first polymer shell having an acid number of from 5 to 100, the first polymer having a calculated Mn of from 1000 to 4500 and a calculated Tg of lower then 100° C.; and from 70% to 90% by wt., based on the wt. of the multistage emulsion polymer, of a second polymer core having an acid number of from 0 to one-half the acid number of the first polymer, the second polymer having a calculated Mn of greater than 20,000.
1. A multistage emulsion polymer comprising:
from 10% to 30% by wt., based on the wt. of said multistage emulsion polymer, of a first polymer shell having an acid number of from 5 to 100, said first polymer having a calculated Mn of from 1000 to 4500 and a calculated Tg of lower than 100° C.; and
from 70% to 90% by wt., based on the wt. of said multistage emulsion polymer, of a second polymer core having an acid number of from 0 to one-half the acid number of said first polymer, said second polymer having a calculated Mn of greater than 20,000.
2. The multistage emulsion polymer of claim 1 wherein the acid number of said first polymer is from 30 to 65.
3. The multistage emulsion polymer of claim 1 or claim 2 wherein the calculated Tg of said first polymer is lower than 80° C.
4. An aqueous coating composition comprising a multi-stage aqueous emulsion polymer comprising
from 10% to 30% by wt., based on the wt. of said multistage emulsion polymer, of a first polymer shell having an acid number of from 5 to 100, said first polymer having a calculated Mn of from 1000 to 4500 and a calculated Tg of lower than 100° C.; and
from 70% to 90% by wt., based on the wt. of said multistage emulsion polymer, of a second polymer core having an acid number of from 0 to one-half the acid number of said first polymer, said second polymer having a calculated Mn of greater than 20,000.
5. The aqueous coating composition of claim 4 wherein the acid number of said first polymer is from 30 to 65.
6. The aqueous coating composition of claim 4 or claim 5 wherein the calculated Tg of said first polymer is lower than 80° C.
7. A method for providing a coating comprising
(a) forming an aqueous coating composition comprising a multi-stage aqueous emulsion polymer comprising
from 10% to 30% by wt., based on the wt. of said multistage emulsion polymer, of a first polymer shell having an acid number of from 5 to 100, said first polymer having a calculated Mn of from 1000 to 4500 and a calculated Tg of lower than 100° C.; and
from 70% to 90% by wt., based on the wt. of said multistage emulsion polymer, of a second polymer core having an acid number of from 0 to one-half the acid number of said first polymer, said second polymer having a calculated Mn of greater than 20,000;
(b) applying said aqueous coating composition to a substrate; and
(c) drying, or allowing to dry, said applied aqueous coating composition.
8. The method for providing a coating of claim 7 wherein the acid number of said first polymer is from 30 to 65.
9. The method for providing a coating of claim 7 or claim 8 wherein the calculated Tg of said first polymer is lower than 80° C.