Low-density thermosetting sheet molding compounds
View Patent ↗This invention relates to low-density thermosetting sheet molding compounds (SMC) including a treated inorganic clay, a curative, a low profile agent, a reinforcing agent, and preferably a low-density filler. The thermosetting SMC are used to prepare exterior and structural thermoset articles, e.g. auto parts, panels, etc.
1. A thermosetting sheet molding composition that will produce molded articles having density of 1.1 g/cm3 to 1.7 g/cm3 comprising:
(a) from 30 to 50 parts of a thermosetting resin;
(b) from 1 to 10 parts of a treated inorganic clay;
(c) from 10 to 40 parts of a low profile additive;
(d) from 15 to 40 parts of fiber glass; and
(e) from 0 to 35 parts of an inorganic filler,
wherein said parts by weight are based on 100 parts of sheet molding composition.
2. The thermosetting molding composition of claim 1 wherein the treated clay is prepared in situ.
3. The thermosetting molding composition of claim 1 wherein the treated clay is prepared by ion exchange.
4. The thermosetting sheet molding composition of claim 2 or 3 which further comprises a filler.
5. The thermosetting sheet molding composition of claim 4 further comprising a fiberglass as a reinforcing agent wherein the reinforcing agent is fiberglass.
6. The thermosetting sheet molding composition of claim 5 wherein the filler is a low-density filler.
7. The thermosetting sheet molding composition of claim 6 wherein the thermosetting resin is selected from the group consisting of unsaturated polyester resins, vinyl ester resins, and mixtures thereof.
8. The thermosetting sheet molding composition of claim 7 wherein the unsaturated polyester resin has an average molecular weight of 500 to 5,000.
9. The thermosetting sheet molding composition of claim 8 which further contains an ethylenically unsaturated monomer.
10. The thermosetting sheet molding composition of claim 9 wherein the ethylenically unsaturated monomer is styrene.
11. The thermosetting sheet molding composition of claim 10 which further comprises an initiator, a stabilizer, and a thickening agent.
12. A thermoset molded article having a density of from 1.1 to 1.7 grams/cm 3 prepared by a process comprising:
(a) introducing a thermosetting sheet molding composition comprising:
(1) from 30 to 50 parts of a thermosetting resin;
(2) from 1 to 10 parts of a treated inorganic clay;
(3) from 10 to 40 parts of a low profile additive;
(4) from 15 to 40 parts of fiber glass; and
(5) from 0 to 35 parts of an inorganic filler,
into a pattern, wherein said parts by weight are based on 100 parts of sheet molding composition;
(b) curing the shape prepared by (a).
13. The molded article of claim 12 wherein the treated clay is prepared in situ.
14. The molded article claim 12 wherein the treated clay is prepared by ion exchange.
15. The molded article of claim 14 further comprising a fiberglass as a reinforcing agent wherein the reinforcing agent is fiberglass.
16. The molded article of claim 15 wherein the filler is a low-density filler.
17. The molded article of claim 16 wherein the thermosetting resin is selected from the group consisting of unsaturated polyester resins, vinyl ester resins, and mixtures thereof.
18. The molded article of claim 17 wherein the unsaturated polyester resin has an average molecular weight of 500 to 5,000.
19. The molded article of claim 18 which further contains an ethylenically unsaturated monomer.
20. The molded article of claim 19 wherein the ethylenically unsaturated monomer is styrene.
21. The molded article of claim 20 which further comprises an organic peroxide initiator, a stabilizer, and a thickening agent.