CONTROLLED SHRINKAGE ULTRAVIOLET LIGHT RESISTANT MOLDING COMPOUND

Abstract

A molding composition formulation is provided that includes a thermoset cross-linkable polymeric resin and an ultraviolet light absorber. A shrinkage-reducing polymeric additive is present in the formulation from between 3 and 30 total weight percent, such that upon cure a linear shrinkage rate of within ±1.0% is obtained. Shrinkage-reducing polymeric additives include a condensation polyester of glycol and a polyacid or acid anhydride, polyvinyl acetate, polymethylmethacrylate, or polyether polyol. A vehicle body component formed through a sheet molding composition formulation is provided as recited above, and includes a fiberglass filler. A process for producing a vehicle body component exposed to ultraviolet light upon environmental exposure of a vehicle includes molding at an elevated temperature above 20° C. the vehicle component from the formulation as detailed above. The process is followed by trimming the molded vehicle component prior to assembly.

Description

Claims

1. A molding composition formulation comprising: a thermoset cross-linkable polymeric resin;an ultraviolet light absorber;a shrinkage-reducing polymeric additive selected from the group consisting of: a condensation polyester of glycol and a polyacid, a condensation polyester of glycol and an acid anhydride, polyvinyl acetate, polymethylmethacrylate, saturated polyester, polyether polyols, copolymers thereof, and a combination thereof said additive being present between 3 and 30 total weight percent such that the formulation upon cure retains a linear paste shrinkage rate of within ±1.0%.

2. The formulation of claim 1 wherein said shrinkage-reducing additive is in combination said condensation polyester of glycol and the polyacid or said condensation polyester of glycol and the acid anhydride and said polymethylmethacrylate.

3. The formulation of claim 2 wherein a weight ratio of said condensation polyester of glycol and a polyacid or said condensation polyester of glycol and the acid anhydride: polymethylmethacrylate acetate is 1:02-5.

4. The formulation of claim 1 wherein said shrinkage-reducing additive is present from 4 to 14 total weight percent.

5. The formulation of claim 1 wherein said UV light degradation inhibitor includes at least one of a benzotriazole, a benzophenone, a sterically hindered amine, carbon black, mixed metal oxides particulate of the formula M×MzyO(ax+zy)/2, where Ma is a transition metal of a Group other than VIII having an oxidation state +a, x is a rational value greater than zero and less than 4, Mz is a transition metal of exclusive of Fe, Co, Ru, Rh, Pd, Os, Ir, and Pt that has an oxidation state +z, and, y is a rational value greater than zero and less than 4 so x+y is equal to or greater than 2 with the proviso that if carbon black is present a carbon black amount is from 2 to 3 organic matrix weight percent.

6. The formulation of claim 1 wherein said resin is an unsaturated polyester.

7. The formulation of claim 1 wherein said resin is selected from the group consisting of: propylene glycol maleic anhydride, a neopentyl propylene glycol maleic anhydride, or a combination thereof.

8. The formulation of claim 1 further comprising an ethylenically unsaturated monomer.

9. The formulation of claim 1 further comprising at least one additional substance selected from the group consisting of: a free radical initiator, polymerization inhibitor, particulate filler, fiber filler, a mold release agent, a low profile additive, a plasticizer, a flame retardant, a thickener, and a colorant.

10. The formulation of claim 9 wherein said at least one additional substance is a glass fiber filler.

11. A vehicle body component comprising: a thermoset polymeric resin cured into a form of the vehicle body component and having a linear paste shrinkage rate of within ±1.0% comprising an ultraviolet light absorber; a shrinkage-reducing polymeric additive selected from the group consisting of: a condensation polyester of glycol and a polyacid, a condensation polyester of a glycol and an acid anhydride, polyvinyl acetate, polymethylmethacrylate, saturated polyester, a polyether polyol, copolymers thereof, and a combination thereof; and a fiberglass filler.

12. The automotive body component of claim 11 wherein the form is a tonneau cover.

13. The automotive body component of claim 11 wherein the form is a truck box.

14. The automotive body component of claim 11 wherein the form is a vehicle panel selected from the group consisting of: tailgate and midgate.

15. The automotive body component of claim 11 wherein the form is a running board.

16. The automotive body component of claim 11 wherein the form is a truck box.

17. A process for producing a vehicle body component exposed to ultraviolet light upon environmental exposure of a vehicle consisting of: molding at elevated temperature above 20° C. the vehicle component from a formulation of claim 1 and independent of a UV protective coating; andtrimming the molded vehicle component prior to assembly.

18. The process of claim 17 wherein the formulation is a sheet molding composition.