Curable fluoroelastomer composition
View Patent ↗Fluoroelastomer compositions comprising fluoroelastomers having copolymerized units of a nitrile-containing cure site monomer are cured with certain hydrazide curatives. The hydrazide is of the general formula R 1 C(O)NHNHR 2 , wherein R 1 is alkyl, aryl, benzyl, heterocycle, fluoroalkyl, or H; R 2 is H, alkyl, aryl, heterocycle, CO 2 R 3 , C(O)H, or CH 2 R 4 ; R 3 is alkyl, CH 2 R 4 , aryl, benzyl, or heterocycle; and R 4 is a fluoroalkyl group.
1. A curable composition comprising:
A) a fluoroelastomer comprising copolymerized units of a nitrile group-containing cure site monomer; and
B) a hydrazide of the general formula R 1 C(O)NHNHR 2 , wherein said oxygen atom may optionally be replaced by a sulfur atom and wherein R 1 is benzyl, fluoroalkyl, or H; R 2 is H, alkyl, aryl, heterocycle, CO 2 R 3 , C(O)H, or CH 2 R 4 ; R 3 is alkyl, CH 2 R 4 , aryl, benzyl, or heterocycle; and R 4 is a fluoroalkyl group.
2. A curable composition of claim 1 wherein R 1 is H and R 2 is H or CO 2 R 3 .
3. A curable composition of claim 2 wherein said hydrazide is formic hydrazide.
4. A curable composition of claim 1 wherein R 1 is benzyl and R 2 is H or CO 2 R 3 .
5. A curable composition of claim 1 wherein R 1 is fluoroalkyl and R 2 is H or CO 2 R 3 .
6. A curable composition of claim 1 further comprising a curative accelerator.
7. A cured article made from the composition of claim 1 .
8. A cured article of claim 7 having a volume swell, measured according to ASTM D1414, after exposure to 225° C. water for at least 168 hours of less than 5% and a compression set, 300° C., 70 hours, 15% compression, measured according to ASTM D395, of less than 70%.
9. A curable composition comprising:
A) a fluoroelastomer comprising copolymerized units of a nitrile group-containing cure site monomer; and
B) a hydrazide selected from the group consisting of benzhydrazide; 2-hydroxybenzhydrazide; isophthalic dihydrazide; and isoniazide.
10. The curable composition of claim 9 wherein said hydrazide is selected from the group consisting of benzhydrazide; 2-hydroxybenzhydrazide; and isophthalic dihydrazide.
11. The curable composition of claim 9 wherein said hydrazide is selected from the group consisting of isoniazide.
12. A cured article made from the composition of claim 9 .
13. A cured article of claim 12 having a volume swell, measured according to ASTM D1414, after exposure to 225° C. water for at least 168 hours of less than 5% and a compression set, 300° C., 70 hours, 15% compression, measured according to ASTM D395, of less than 70%.