Low temperature, cationically curable compositions with improved cure speed and toughness
View Patent ↗The present invention relates to low temperature, cationically curable compositions with improved cure speed and toughness.
1. A cationically curable composition comprising:
a. a cycloaliphatic epoxy;
b. a hydroxyl-functionalized aliphatic polyester;
c. a rubber component having a particle size on the order of 10 −9 meters dispersed in a cationically curable epoxy;
d. a silica component having a particle size on the order of 10 −9 meters dispersed in a cationically curable epoxy; and
e. a cationic cure catalyst, wherein when cured at a temperature of 100° C. for a period of time of 60 minutes the composition demonstrates tensile peel strength on mild steel substrates spaced apart by 250 nm of greater than about 11 N/mm.
2. The composition of claim 1 , wherein the cycloaliphatic epoxy has two or more epoxy groups.
3. The composition of claim 1 , which cures when exposed to a temperature of 100° C. for a period of time of 30 to 60 minutes.
4. The composition according to claim 1 , wherein the rubber component is a core shell rubber.
5. The composition according to claim 1 , wherein the rubber component is surface modified rubber.
6. The composition of claim 1 , wherein the cycloaliphatic epoxy and the polyester are present in a by weight ratio of 2.5:1 to 3.5:1.
7. The composition according to claim 1 , wherein the cationic cure catalyst includes a cationic counter ion within the following structure:
wherein R 1 , R 2 , R 3 ′ R 4 , R 5 and R 5 ′ are selected from hydrogen, C 1 - 6 alkyl, C 2-6 alkenyl, halogen, hydroxyl and carboxyl, with R′, R 2 , R 5 and R 5 ′ being present individually up to 5 times on each aromatic ring to which it(they) is(are) attached, and R 3 and R 4 being present individually up to 4 times on each aromatic ring to which it(they) is(are) attached, n is 0-3 and m is 0-1.
8. The composition according to claim 1 , wherein the cationic cure catalyst includes a counter cation selected from the group consisting of
9. The composition according to claim 1 , wherein the cationic cure catalyst includes a counter cation selected from the group consisting of
wherein for structure IV R 6 , R 7 , R 8 , R 9 and R 10 are selected from hydrogen, alkyl of from 1 to 5 carbon atoms, halogen, hydroxyl, and carboxyl, for structure V R 6 , R 7 , R 8 , R 9 , R 10 , R 6 ′, R 7 ′, R 8 ′, R 9 ′, and R 10 ′ are selected from hydrogen, alkyl of from 1 to 5 carbon atoms, halogen, hydroxyl, and carboxyl, and for structure VI R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , and R 21 are selected from hydrogen, alkyl of from 1 to 5 carbon atoms, halogen, hydroxyl, and carboxyl.
10. The composition according to claim 1 , wherein the cationic cure catalyst includes a counter cation selected from the group consisting of
11. The composition according to claim 1 , wherein the cationic cure catalyst is used in an amount within the range of about 0.1 to about 2 percent by weight of the total composition.
12. The composition according to claim 1 , wherein the cationic cure catalyst is an ammonium antimony hexafluoride.
13. The composition according to claim 1 , wherein the cationic cure catalyst includes a cation selected from the group consisting of onium, iodonium and sulfonium.
14. The composition of claim 1 , wherein the cationic cure catalyst includes an anion selected from the group consisting of tetrakis(pentafluorophenyl)borate, hexafluorophosphate and hexafluoroantimonate.