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)) n NHNHR 2 , wherein n is 1 or 2; R 1 is NH 2 , NHNH 2 , NHR 3 , NR 3 2 , NHNHC(O)NH 2 , NHNHC(O)NHNH 2 , NHNHR 2 , or NHC(O)NHNH 2 ; R 2 is H, alkyl, aryl, heterocycle, CO 2 R 3 , C(O)R 3 , CH 2 R 4 , or C(O)R 4 ; R 3 is alkyl, aryl, heterocycle, or CH 2 R 4 ; 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)) n NHNHR 2 , wherein said oxygen atom may optionally be replaced with a sulfur atom and wherein n is 1 or 2; R 1 is NH 2 , NHNH 2 , NHR 3 , NR 3 2 , NHNHR 2 , or NHC(O)NHNH 2 ; R 2 is H, CO 2 R 3 , CH 2 R 4 or C(O)R 4 ; R 3 is alkyl, aryl, heterocycle, or CH 2 R 4 ; and R 4 is a fluoroalkyl group.
2. A curable composition of claim 1 wherein n is 1; R 1 is NH 2 , NHNH 2 , NHR 3 , NR 3 2 , NHNHR 2 , or NHC(O)NHNH 2 ; and R 2 is H.
3. A curable composition of claim 1 wherein n is 2; R 1 is NH 2 , NHNH 2 , NHR 3 , NR 3 2 , NHNHR 2 , or NHC(O)NHNH 2 ; and R 2 is H.
4. A curable composition of claim 1 wherein n is 1; R 1 is NH 2 , NHNH 2 , NHR 3 , NR 3 2 , NHNHR 2 , or NHC(O)NHNH 2 ; and R 2 is CO 2 R 3 .
5. A curable composition of claim 1 wherein n is 2; R 1 is NH 2 , NHNH 2 , NHR 3 , NR 3 2 , NHNHR 2 , or NHC(O)NHNH 2 ; and R 2 is CO 2 R 3 .
6. A curable composition of claim 1 wherein said hydrazide is selected from the group consisting of carbohydrazide; 4-phenylsemicarbazide; 4-phenylsemicarbazide hydrochloride; 4,4-diphenylsemicarbazide; oxamic hydrazide; oxalyldihydrazide; semicarbazide; thiocarbohydrazide; and thiosemicarbazide.
7. A curable composition of claim 1 further comprising a curative accelerator.
8. A cured article made from the composition of claim 1 .
9. A cured article of claim 8 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%.