Polymeric thickener for molding compounds
View Patent ↗A molding composition is provided that includes a thermoset cross-linkable polymeric resin, a fibrous filler and a thickener system. The thickener system includes an amine and an isocyanate that are reactive to form a polyurea. The polyurea is operative to thicken the molding composition formulation prior to polymeric resin thermoset with superior properties relative to conventional thickener systems. A molded article produced from a cross-linked thermoset polymeric resin containing fibrous filler and a polyurea present from 1 to 5 total weight percent of the article either forms an interpenetrating network between the resin and the polyurea or the resin and polyurea crosslink upon resin thermoset to further strengthen the resulting article. An alkali earth oxide or hydroxide simultaneously thickens through interaction with carboxylate functionality of the cross-linkable resin to provide a superior viscosity build and humidity tolerance.
1. A molding composition formulation comprising:
a thermoset cross-linkable polyester polymeric resin;
a thickener system comprising a polyether amine and an isocyanate present in an equivalent group number ratio of isocyanate groups:amine groups of between 4.5:1 and 1:4.4 that are reactive to form a polyether polyurea forming an interpenetrating network with said cross-linkable polyester polymeric resin and present from 1 to 3.7 total weight percent of the formulation; and
an additive present from 0.1 to 0.9 total weight and selected from the group consisting of: magnesium oxide, magnesium hydroxide, and calcium oxide.
2. The formulation of claim 1 wherein said additive is present from 0.1 to 0.5 total weight percent.
3. The formulation of claim 1 wherein said amine is a triamine.
4. The formulation of claim 1 wherein said amine has a molecular weight of between 120 and 5,000 Daltons and has a polyether backbone.
5. The formulation of claim 3 wherein said triamine has a polyether backbone.
6. The formulation of claim 1 wherein said additive is magnesium oxide or magnesium hydroxide.
7. The formulation of claim 1 wherein said additive is calcium oxide.
8. The formulation of claim 1 wherein said isocyanate is a diisocyanate.
9. The formulation of claim 1 wherein said isocyanate is a polyisocyanate.
10. The formulation of claim 9 wherein said polyisocyanate is an isocyanate-terminated polyurethane.
11. The formulation of claim 9 wherein said polyisocyanate has a molecular weight of between 400 and 50,000 and a component selected from the group consisting of: a polyether polyol, a polyester polyol, and a diamine.
12. A process for thickening a molding composition formulation comprising:
adding a quantity of an isocyanate having an isocyanate group equivalent number and a quantity of a polyether amine having an amine equivalent group number such that the isocyanate equivalent group number:amine equivalent group number ratio is between 4.5:1 and 1:4.4 to a molding composition formulation containing a thermoset polyester cross-linkable polymeric resin, the quantity of said amine and the quantity of said polyisocyanate being between 1 and 3.7 total weight percent;
introducing an additive in an amount of between 0.1 and 0.9 total weight percent and selected from the group consisting of magnesium oxide, magnesium hydroxide and calcium oxide; and
allowing sufficient time for said amine and said isocyanate to react to form a polyether polyurea interpenetrating network prior to cross-linking of said thermoset polyester cross-linkable resin.
13. The process of claim 12 wherein said amine is selected from the group consisting of: a diamine, a triamine or a combination thereof.
14. The process of claim 12 wherein said isocyanate is a diisocyanate.
15. The process of claim 12 wherein said isocyanate is a polyisocyanate.
16. The process of claim 12 wherein the molding composition formulation has an initial viscosity build of 20,000 centipoise, a viscosity build of 130,000 centipoise 15 minutes thereafter, a viscosity build between about 30,000,000 to 40,000,000 centipoise at 24 hours and has a viscosity that 10 days later is no more than 60,000,000 centipoise.
17. The process of claim 12 further comprising cross-linking said polyurea to said cross-linkable polymeric resin.
18. A molded article produced from a molding composition formulation comprising:
an additive in an amount of between 0.1 and 0.9 total weight percent and selected from the group consisting of magnesium oxide, magnesium hydroxide and calcium oxide;
a cross-linked thermoset polyester polymeric resin;
a fibrous filler coated by said resin;
a polyether polyurea formed from an isocyanate and an amine with an equivalent group number ratio of isocyanate group:amine group of between 4.5:1 and 1:4.4 and said polyether polyurea being present from 1 to 3.7 total weight percent of the article and forming an interpenetrating network with the thermoset polyester polymeric resin.
19. The article of claim 18 wherein said resin is cross-linked to said polyurea.