Fillers
A powdered filler composed of solid particles of a cured thermosetting composition comprising a resin modifier such as fumed silica, methods of preparing the cured solid particles, compositions comprising the powdered filler, and articles made from the compositions are disclosed. In embodiments, the solid particles are spherical shaped, transparent or translucent, and have a mean particle size of less than 20 μm.
1. A method of preparing a powdered resin filler, comprising:
a) combining a thermosetting ethylenically-unsaturated curable composition, a surfactant, a curing agent and a hydrophilic resin modifier to form a resin blend composition, wherein the hydrophilic resin modifier is 0.5 to 12 Wt. % of the resin blend composition;
b) dispersing the resin blend composition in an aqueous medium to form an oil-in-water emulsion or dispersion;
c) curing the oil-in-water emulsion or dispersion to form a particle slurry; and
d) drying the particle slurry to a powder form comprising resin particles having a mean particle size of 1 to 20 μm.
2. The method of claim 1 , wherein the hydrophilic resin modifier is hydrophilic fumed silica.
3. The method of claim 1 , wherein the resin particles are transparent.
4. The method of claim 1 , wherein the resin particles are substantially spherical shaped.
5. The method of claim 1 , further comprising, after drying the particle slurry, reducing the size of the particles.
6. A powdered filler, consisting essentially of cured resin particles having a mean particle size of 1 to 20 μm, wherein the resin particles are the reaction product of curing a resin blend composition in an oil-in-water emulsion or dispersion comprising:
A. a thermosetting ethylenically-unsaturated curable composition;
B. surfactant;
C. hydrophilic resin modifier; and
D. curing agent;
wherein the hydrophilic modifier resin is 0.5 to 12 Wt. % of the resin blend composition;
wherein the thermosetting ethylenically-unsaturated curable composition is in an amount greater than the hydrophilic resin modifier.
7. The powdered filler of claim 6 , wherein the hydrophilic resin modifier is hydrophilic fumed silica.
8. The powdered filler of claim 6 , wherein the resin blend composition comprises:
A. 75 to 98 Wt. % ethylenically-unsaturated thermosetting composition;
B. 0.5 to 5 Wt. % surfactant;
C. 0.5 to 12 Wt. % hydrophilic resin modifier; and
D. 0.5 to 5 Wt. % curing agent; the Wt. % based on the total weight of the resin blend composition.
9. The powdered filler of claim 6 , wherein the resin particles are translucent.
10. The powdered filler of claim 6 , wherein the resin particles are substantially spherical shaped.
11. A powdered filler consisting essentially of cured resin particles, the particles comprising:
a cured thermoset composition comprising the reaction product of curing a resin blend composition in an oil-in-water emulsion or dispersion, wherein the resin blend comprises a thermosetting ethylenically-unsaturated curable composition and a hydrophilic resin modifier;
wherein the cured resin particles are spherical-shaped, transparent, and have a mean particle size of 1 to 20 μm;
wherein the cured thermosetting ethylenically-unsaturated curable composition is in an amount greater than the hydrophilic resin modifier, and wherein the hydrophilic resin modifier is 0.5 to 12 Wt. % of the resin blend composition.
12. The powdered filler of claim 11 , wherein the hydrophilic resin modifier is hydrophilic fumed silica.
13. A gel coat composition, comprising:
the powdered filler of claim 8 dispersed in a resin matrix;
wherein the resin particles are visually non-differentiable from the resin matrix.
14. A gel coat composition of claim 13 with an L value of 6 to 7.2.
15. The gel coat composition of claim 13 , wherein the hydrophilic resin modifier is hydrophilic fumed silica.
16. A method of preparing a gel coat composition, comprising combining 50 to 99 Wt. % gel coat composition and 1 to 50 Wt. % of the powdered filler of claim 11 , based on the total weight of the gel coat composition.
17. A method of preparing a gel coated article, comprising:
A. Applying a layer of a gel coat composition to a surface of a mold, the gel coat composition comprising a resin matrix with the powdered filler of claim 11 dispersed therein;
B. Allowing the gel coat composition to partially cure;
C. Applying a composite material and laminating resin onto the layer of the partially cured gel coat composition;
D. Allowing the gel coat composition and laminating resin to cure within the mold to form a composite article having a surface coated with the cured gel coat; and
E. Removing the gel coated article from the mold;
wherein the resin particles of the powder filler in the gel coat are visually non-differentiable from the resin matrix of the cured gel coat.
18. The method of preparing a gel coated article of claim 17 , wherein the L value of the gel coat is 6 to 7.2.
19. The powdered filler of claim 8 , wherein the hydrophilic resin modifier is 2 to 5 Wt. % of the resin blend composition.
20. The gel coat composition of claim 13 , further comprising a black pigment.