Co-cured gel coats, elastomeric coatings, structural layers, and in-mold processes for their use
Co-cured urethane and vinyl ester, epoxy, or unsaturated polyester gel coats having improved toughness and flexibility compared with conventional polyester gel coats are disclosed. The gel coats, which have 10-50 wt. % urethane content, adhere well to structural layers and can be used in a traditional in-mold process. Co-cured elastomeric coatings comprising from 50 to 95 wt. % of a urethane component and an unsaturated polyester, epoxy, or vinyl ester are also disclosed. Unlike conventional urethane coatings, the elastomeric coatings adhere well to structural layers and can be used in a traditional in-mold process. Castings or structural layers comprising a reinforced thermoset of co-cured urethane and vinyl ester, epoxy, or unsaturated polyester components, including 10-95 wt. % of the urethane component, are also described. The invention includes in-mold processes for making laminates that utilize the gel coats, elastomeric coatings, and/or structural layers. The in-mold process gives flexible, durable, urethane-containing laminates having good interlayer adhesion.
1. A gel coat comprising co-cured urethane and vinyl ester, epoxy, or unsaturated polyester components, wherein
(a) the urethane component is from 10 to 50 wt. % based on the amount of gel coat; and
(b) urethane and vinyl ester, epoxy, or unsaturated polyester reactants excluding hydroxyl-terminated unsaturated polyester polyols are combined under conditions effective to cure both components in the same cure cycle.
2. The gel coat of claim 1 wherein the vinyl ester reactants comprise styrene and a vinyl ester resin comprising a reaction product of an epoxy resin and an unsaturated carboxylic acid.
3. The gel coat of claim 1 wherein the unsaturated polyester reactants comprise styrene and an isophthalate-based unsaturated polyester resin.
4. The gel coat of claim 1 wherein the epoxy reactants comprise an epoxy resin and an aromatic diamine.
5. The gel coat of claim 1 wherein the urethane component is from 10 to 25 wt. % based on the amount of gel coat.
6. The gel coat of claim 1 wherein the urethane reactants comprise a polyol, a polyisocyanate, an optionally a chain extender.
7. A laminate comprising the gel coat of claim 1 and at least one structural layer bonded to the gel coat.
8. A casting comprising co-cured urethane and vinyl ester, epoxy, or unsaturated polyester components, wherein
(a) the urethane component is from 10 to 50 wt. % based on the amount of casting; and
(b) the urethane and vinyl ester, epoxy, or unsaturated polyester reactants excluding hydroxyl-terminated unsaturated polyester polyols are combined under conditions effective to cure both components in the same cure cycle.