Room temperature curable water-based mold release agent for composite materials
View Patent ↗A room temperature curable water-based mold release agent that is useful for demolding composite parts, such as epoxy and polyester based polymer materials. The mold release agent is curable at low temperatures, such as room temperature, but is thermally stable up to conventional epoxy based composite molding temperatures, e.g., greater than 200 or 280° C. The mold release agent is useful for demolding large composite parts that are cured in large ovens at high temperature when the molds themselves are prepped at room temperature before placing in the oven. The mold release agent is also useful for demolding polyester composite parts that are prepared and cured at low temperature such as room temperature.
1. A mold release composition having a pH of 7 to 11 prepared from a group of ingredients comprising:
0.009 to 10% by weight of a functional siloxane, having the following structure:
where R 1 , R 2 , R 3 , R 4 , R 5 and R 6 individually can be the same or different, each being selected from the group consisting of C 1-3 alkyl, vinyl, hydride, and alkoxy groups, where n is about 0 to about 100,000, and where P 1 and P 2 can be the same or different, each being selected from the group consisting of silanol, hydride, hydroxyl, alkyl, vinyl, carbinol and carboxy groups;
0.09 to 10% by weight of a crosslinkert;
0.001 to 2% by weight of a catalyst;
0.02 to 6.4% by weight of a thickening agent; and further comprising 0.04 to 4% by weight of a base additional to each of the functional siloxane, the crosslinker and the thickening agent; and water.
2. A mold release composition according to claim 1 , wherein the crosslinker has the general formula X-SiABC where X is selected from the group consisting of methyl, vinyl, alkoxy, acetoxy, hydride and ethyl groups, and A, B and C are each individually an alkoxy group.
3. A mold release composition according to claim 1 , having less than 5 grams VOCs per liter of said mold release composition.
4. A mold release composition according to claim 1 , further comprising at least one component selected from the group consisting of a wetting agent, a surfactant, a slip agent, a dye and a transfer control agent.
5. A mold release composition according to claim 1 , having a viscosity of 10-10,000 cP at 25° C.
6. A mold release composition according to claim 1 , said functional siloxane having the following structure: HO(CH 3 ) 2 —Si—(O—Si(CH 3) 2 —O—Si(CH 3 ) 2 ) x —O—Si(CH 3 ) 2 OH, where x is selected such that said functional siloxane has a molecular weight in the range of 4,000- 100,000.
7. A mold release composition according to claim 1 , said mold release composition being curable at room-temperature.
8. A mold release composition according to claim 1 , comprising the following composition:
0.04-2.99 weight percent silanol-functional siloxane;
0.018-4.98 weight percent alkoxy-functional crosslinker;
0.009-2 weight percent catalyst;
0.04-4.8 weight percent thickening agent activatable at a pH of 7 to 11; and
0.1-2 weight percent base.
9. A mold release composition according to claim 1 , wherein at least one of P 1 and P 2 is hydroxyl.
10. A mold release composition according to claim 1 wherein the crosslinker is selected from a tri-alkoxy functional silane and a tetra-alkoxy functional silane.
11. A mold release composition according to claim 1 , having a shelf life of greater than five months at about 25° C.
12. A mold release composition according to claim 1 , wherein the thickening agent is activatable at a pH of 7 to 11, the activated thickening agent providing the mold release composition with a viscosity of 10-10,000 cP at 25° C.
13. The mold release composition according to claim 1 wherein the base is a separate component from the functional siloxane, the crosslinker and the thickening agent.
14. The mold release composition according to claim 1 wherein cured products of the mold release composition have substantially no detrimental transfer to the surface of a composite molded part.
15. A mold release composition prepared from at least:
0.04 to 3 percent by weight of a functional siloxane, having the following structure,
where R 1 , R 2 , R 3 , R 4 , R 5 and R 6 individually can be the same or different, each being selected from the group consisting of C 1-3 alkyl, vinyl, hydride, and alkoxy groups, where n is about 0 to about 100,000, and where P 1 , and P 2 can be the same or different, each being selected from the group consisting of silanol, hydride, hydroxyl, alkyl, vinyl, carbinol and carboxy groups;
0.18 to 5 percent by weight of a functional crosslinker having the formula X-SiABC where X is selected from the group consisting of methyl, vinyl, alkoxy, acetoxy, hydride and ethyl groups, and A, B and C are each individually an alkoxy group;
0.04 to 5 percent by weight of a thickening agent activatable at a pH of 7 to 11, the activated thickening agent providing the mold release composition with a viscosity of 10-10,000 cP at 25° C;
0.1 to 2 percent by weight of an ethanolamine base additional to the functional siloxane, the crosslinker and the thickening agent;
optionally, 0.05 to 38 percent by weight of at least one component selected from the group consisting of welling agent, surfactant, slip agent, dye and transfer control agent; and
water;
wherein the mold release composition has 0 to 1 percent by weight of non-functional siloxanes, a pH of 7 to 11 and a shelf life of greater than five months at about 25° C.
16. A mold release composition prepared from a group of ingredients consisting essentially of:
0.009 to 10% by weight of a functional siloxane, having the following structure,
where R 1 , R 2 , R 3 , R 4 , R 5 and R 6 individually can be the same or different, each being selected from the group consisting of C 1-3 alkyl, vinyl, hydride, and alkoxy groups, where n is about 0 to about 100,000, and where P 1 and P 2 can be the same or different, each being selected from the group consisting of silanol, hydride, hydroxyl, alkyl, vinyl, carbinol and carboxy groups;
0.09 to 10% by weight of a functional crosslinker having the formula X-SiABC where X is selected from the group consisting of methyl, vinyl, alkoxy, acetoxy, hydride and ethyl groups, and A, B and C are each individually an alkoxy group;
0.02 to 6.4% by weight of a thickening agent activatable at a pH of 7 to 11, the activated thickening agent providing the mold release composition with a viscosity of 10-10,000 cP at 25° C; 0.04 to 4% by weight of a base additional to the functional siloxane, the crosslinker and the thickening agent;
0.001 to 2% by weight of catalyst; water and
optionally at least one component selected from the group consisting of wetting agent, surfactant, slip agent, dye and transfer control agent;
wherein the mold release composition has a pH of 7 to 11 and a shelf life of greater than five months at about 25° C.
17. A mold release composition according to claim 16 , wherein the mixture is:
0.04-2.99 weight percent functional siloxane;
0.018-4.98 weight percent functional crosslinker;
0.009-2 weight percent catalyst;
0.04-4.8 weight percent thickening agent;
0.1-2 weight percent of an amine base;
optionally 0.04-36.4 weight percent of the at least one component; and
water.
18. A mold release composition according to claim 16 , wherein the mixture consists of the functional siloxane; the functional crosslinker; the catalyst; the thickening agent; the base; the water and optionally the at least one component.