Powder primeable low moisture SMC
View Patent ↗Sheet molding composition formulation includes a thermoset cross-linkable polymeric resin. A moisture reducing polymeric additive includes at least one of polystyrene; poly C 1 -C 4 alykylmethacrylate; a copolymer of styrene with at least one of butadiene, acrylonitrile and vinyl chloride; or a combination of polystyrene, polyaklymethacrylate and or a styrene copolymer. Moisture reducing polymeric additive is present within the formulation from between 1 and 20 total weight percent. An article formed from such a sheet molding composition formulation defines an article shape and has a surface that sets the article shape with less than 0.5 total weight percent water after 96 hours exposure and 100° F. 100% humidity. The article shape is amendable to receiving a vapor barrier coating applied to the articles shape surface. A powder prime coating over lies the barrier coating and achieves surface finish results comparable to article shapes formed of steel.
1. A sheet molding composition formulation comprising:
a thermoset cross-linkable polymeric resin having a linear shrinkage rate of ±0.06%; and
a moisture reducing polymeric additive selected from the group consisting of: polystyrene; poly C 1 -C 4 alkylmethacrylate; butadiene; polyether; and a copolymer styrene with at least one of butadiene, acrylonitrile, and vinyl chloride; and a combination thereof, said additive being present between 1 and 30 total weight percent and that retains the linear shrinkage rate of ±0.06%;
wherein the formulation has a water content after 96 hours at 100° Fahrenheit at 100% humidity of less than 0.5 total weight percent.
2. The formulation of claim 1 wherein said moisture reducing additive comprises polystyrene.
3. The formulation of claim 1 wherein said moisture reducing additive is present from 3 to 30 total weight percent and consists of polystyrene present from 3 to 14 total weight percent and at least one optional moisture reducing additive selected from poly C 1 -C 4 alkylmethacrylate, butadiene, polyether, and said copolymer.
4. The formulation of claim 1 wherein said additive is present from 3 to 14 total weight percent.
5. The formulation of claim 1 wherein said moisture reducing additive comprises polystyrene and at least one of poly C 1 -C 4 alkylmethacrylate, butadiene, polyether, and said copolymer, where polystyrene is a principal fraction of said additive.
6. The formulation of claim 1 further comprising an ethylenically unsaturated monomer.
7. The formulation of claim 1 wherein said additive is on a weight basis ratio polystyrene: poly C 1 -C 4 alkylmethacrylate: styrene copolymer 1:0.3-0.9:0.1-0.5and said additive is present from 3 to 20 total weight percent of the formulation.
8. The formulation of claim 7 further comprising a nanocomposite clay.
9. The formulation of claim 1 wherein said additive comprises a poly C 1 -C 4 alkylmethacrylate.
10. The formulation of claim 1 wherein said additive comprises a styrene copolymer.
11. The formulation of claim 1 further comprising a nanocomposite clay.
12. A powder primed article comprising:
a sheet molding formulation of claim 1 defining an article form and having a surface wherein the form gains less 0.5 total weight percent water after 96 hours exposure to 100 degree Fahrenheit at 100% humidity;
a vapor barrier coating applied to the surface; and
a powder prime coating overlying said barrier coating.
13. The article of claim 12 further comprising a nanocomposite clay incorporated within the sheet molding formulation.
14. The article of claim 12 wherein said sheet molding formulation comprises polystyrene.
15. The article of claim 12 wherein said sheet molding formulation comprises polystyrene.
16. A vehicle body component formed from a sheet molding composition formulation comprising:
a thermoset polymeric resin cured into a form and having a linear shrinkage rate of ±0.06% containing a moisture reducing polymeric additive selected from the group consisting of: polystyrene; poly C 1 -C 4 alkylmethacrylate; butadiene; polyether; and a copolymer styrene with at least one of butadiene, acrylonitrile, and vinyl chloride; and a combination thereof, said additive being present between 1 and 30 total weight percent and that retains the linear shrinkage rate of ± 0.06%;
wherein the formulation has a water content after 96 hours at 100° Fahrenheit at 100% humidity of less than 0.5 total weight percent.
17. The automotive body component of claim 16 wherein the form is a vehicle bumper beam.
18. The automotive body component of claim 16 wherein the form is a vehicle door panel component.
19. The automotive body component of claim 16 wherein the form is a vehicle floor component.
20. The automotive body component of claim 16 wherein the form is a vehicle spoiler.
21. The automotive body component of claim 16 wherein the form is a vehicle hood.
22. The automotive body component of claim 16 wherein the form gains less 0.5 total weight percent water after 96 hours exposure to 100 degree Fahrenheit at 100% humidity and further comprising
a vapor barrier coating applied to the form; and
a powder prime coating overlying said barrier coating.