Aqueous coating composition
View Patent ↗An aqueous coating composition including a polyurethane polymer which contains carboxylic acid groups, a crosslinking agent, a wetting agent, a slip aid, and a UV stabilizing agent is provided. Coatings prepared from the aqueous coating composition are durable and have low surface friction, flexibility at low temperatures, and adhesion to low surface energy substrates. A method of preparing a substrate coated with the aqueous coating composition and an article containing the coated substrate are also provided. The aqueous coating composition is useful for providing a protective coating with a low friction surface for automotive weatherstrip.
1. An aqueous coating composition comprising, based on the weight of said aqueous coating composition:
a) from 10 to 70 weight % of at least one polyurethane polymer, wherein said polyurethane polymer contains at least two carboxylic acid groups;
b) from 1 to 60 weight % of at least one crosslinking agent;
c) from 0.01 to 4 weight % of at least one wetting agent;
d) from 0.1 to 15 weight % of at least one slip aid; and
e) from 0.01 to 20 weight % UV stabilizing agent.
2. The aqueous coating composition according to claim 1 wherein said polyurethane polymer has an acid number in the range of 5 to 50.
3. The aqueous coating composition according to claim 1 further comprising from 0.5 to 20 weight % flatting agent.
4. The aqueous coating composition according to claim 1 wherein said crosslinking agent contains oxazoline groups.
5. A method of preparing a coated substrate comprising the steps of:
a) preparing an aqueous coating composition comprising:
i) from 10 to 70 weight % of at least one polyurethane polymer,
wherein said polyurethane polymer contains at least two carboxylic acid groups;
ii) from 1 to 60 weight % of at least one crosslinking agent;
iii) from 0.01 to 4 weight % of at least one wetting agent;
iv) from 0.1 to 15 weight % of at least one slip aid; and
v) from 0.01 to 20 weight % UV stabilizing agent;
b) applying said aqueous coating composition to a substrate;
c) drying or allowing to dry said aqueous coating composition to provide a precrosslinked coated substrate; and
d) curing or allowing to cure said precrosslinked coated substrate to provide said coated substrate.
6. The method of claim 5 wherein said substrate is selected from the group consisting of chlorosulfonated polyethylene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, halogenated nitrile rubber, thermoplastic elastomers, thermoplastic polyolefins, propylene oxide polymers, and epichlorohydrin polymers.
7. The method of claim 5 wherein said coated substrate has a coefficient of friction of 3 or less.
8. An article comprising a coated substrate comprising:
a) a substrate; and
b) a coating prepared from an aqueous coating composition comprising:
i) from 10 to 70 weight % of at least one polyurethane polymer,
wherein said polyurethane polymer contains at least two carboxylic acid groups;
ii) from 1 to 60 weight % of at least one crosslinking agent;
iii) from 0.01 to 4 weight % of at least one wetting agent;
iv) from 0.1 to 15 weight % of at least one slip aid; and
v) from 0.0.1 to 20 weight % UV stabilizing agent.
9. The article according to claim 8 wherein said substrate is selected from the group consisting of chlorosulfonated polyethylene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, halogenated nitrile rubber, thermoplastic elastomers, thermoplastic polyolefins, propylene oxide polymers, and epichlorohydrin polymers.
10. The article according to claim 8 wherein said coated substrate has a coefficient of friction of 3 or less.