Method of manufacturing a thermoset polymer utility vault lid

1. A method of manufacturing a fiber reinforced polymer material lid for an utility vault comprising the steps of:

mixing an unsaturated polyester thermosetting material into a resin paste;

compounding the paste into a fiber reinforced composite material sheet;

maturing the compounded fiber reinforced composite material sheet;

cutting the matured compound sheet into a charge pattern;

molding the charge pattern in a mold cavity of a heated mold under pressure to form the lid; and

cooling and machining the lid,

wherein molding the charge pattern in the mold cavity includes forming a textured surface on an upper surface of the lid by having a surface of the mold cavity have a plurality of protrusions which push individual fibers of the fiber reinforced composite sheet away from the upper surface to create a resin rich layer above the individual fibers, and

wherein molding the charge pattern in the mold cavity further includes optionally forming a series of bosses of varying heights to create a gripping surface.

2. The method of claim 1 wherein the mixing step comprises combining polyester resin, polystyrene, a catalyst, a UV inhibitor, a fiber wetting additive, a mold release agent and an inorganic or mineral filler.

3. The method of claim 2 further comprising adding a thickener and a color pigment.

4. The method of claim 1 wherein the compounding step includes:

transferring the resin paste to a first doctor box and a second doctor box;

depositing a first layer of resin paste from the first doctor box onto a first carrier film;

depositing reinforcing fibers onto the first layer of resin paste on the first carrier film;

depositing a second layer of resin paste from the second doctor box onto a second carrier film;

layering the second layer of resin paste on top of the first layer of resin paste containing the reinforcing fibers; and

compacting the first layer of resin paste, reinforcing fibers and second layer of resin paste to form a sheet.

5. The method of claim 1 wherein the maturing step comprises chemically thickening the sheet.

6. The method of claim 1 wherein the molding step comprises the steps of:

compressing the charge pattern in the mold;

transforming the charge pattern from a resin paste into a viscoelastic liquid;

filling the mold cavity with the viscoelastic liquid;

evacuating air from the mold cavity; and

curing the low viscosity liquid in the mold cavity under heat and low pressure.

7. The method of claim 1 wherein the resin matrix paste comprises about 10% to about 40% polyester resin.

8. The method of claim 1 wherein the resin matrix paste comprises about 5% to about 30% polystyrene.

9. The method of claim 1 wherein the resin matrix paste comprises about 15% to about 50% inorganic or mineral filler.

10. The method of claim 1 wherein the compounded fiber reinforced composite material comprises about 5% to about 60% fiber glass.

11. The method of claim 1 further comprising the step of automatically loading the charge pattern into the mold cavity and removing the molded lid and moving the molded lid to a machining station.

12. The method of claim 11 wherein the step of automatically loading the charge pattern and removing the molded lid and moving the molded lid is by a robot.

13. The method of claim 1 wherein forming a textured surface on an upper surface of the lid includes a change of depth into the upper surface.

14. The method of claim 13 wherein the change of depth into the upper surface is of different depths.