Radiation or thermally curable barrier sealants
This invention relates to curable sealants that provide low moisture permeability and good adhesive strength after cure. The composition comprises an aromatic compound having meta-substituted reactive groups and a cationic or radical initiator.
1. A cationically curable barrier composition consisting essentially of:
(a) a meta-substituted aromatic epoxy compound having the general structure:
in which
R 1 , R 2 , R 3 , R 4 are selected from the group consisting hydrogen, halogen, cyano, alkyl, aryl, and substituted alkyl or aryl groups;
R 5 , R 6 are divalent hydrocarbon linkers having the general structure —C n H 2n —, where n=0-4;
L 1 , L 2 , L 3 , L 4 , L 5 , L 6 are either a direct bond or a divalent linking group selected from
EP is an epoxy group selected from the group consisting of aliphatic epoxy, glycidyl ether, and cycloaliphatic epoxy, in which the hydrogens on any of the epoxy groups is optionally substituted by one or more alkyl or halogen groups:
RF is a reactive functionality selected from the groups consisting of EP, an hydroxyl (—OH), a vinyl ether (—O—CH═CH 2 ), a propenyl ether (—O—CH═CH—CH 3 ), a crotyl ether (—O—CH═CH—C 2 H 5 ), a styrenic, an acrylate, a methacrylate, an itaconate, a maleimide, a maleate, a fumarate, a cinnamate, an acrylamide, a methacrylamide, a chalcone, a thiol, an allyl, an alkenyl, and a cycloalkenyl; and
(b) a cationic inititiator, and
(c) one or more epoxy resins selected from the group consisting of bisphenol F diglycidyl ether, novolac glycidyl ethers, polycyclic epoxies, and halogenated glycidyl ethers.
2. The curable barrier composition according to claim 1 in which the EP epoxy group is selected from the group consisting of
in which the hydrogens on the EP structure may be substituted by one or more alkyl or halogen groups.
3. The curable barrier composition according to claim 1 , in which the aromatic compound (a) is selected from the group consisting of:
4. The curable barrier composition according to claim 1 in which the initiator is a cationic initiator selected from the group consisting of a cationic photoinitiator, a Brφnsted acid, a Lewis acid, and a photo- or thermal-acid generator.
5. The cationically curable barrier composition according to claim 1 in which one or more fillers are present.
6. The curable barrier composition according to claim 5 in which one or more fillers are present and are selected from the group consisting of ground quartz, fused silica, amorphous silica, talc, glass beads, graphite, carbon black, alumina, clays, mica, vermiculite, aluminum nitride, boron nitride; silver, copper, gold, tin, tin/lead alloys, poly(tetrachloroethylene), poly(chlorotriflouroethylene), poly(vinylidene chloride), CaO, BaO, Na 2 SO 4 , CaSO 4 , MgSO 4 , zeolites, silica gel, P 2 O 5 , CaCl 2 , and Al 2 O 3 .
7. The curable barrier composition according to claim 1 in which one or more adhesion promoters are present.
8. The curable barrier composition according to claim 7 in which the one or more adhesion promoters are one or more silanes.
9. An electronic or optoelectronic device sealed, coated, or encapsulated with the curable barrier sealant according to claim 1 .
10. The electronic or optoelectronic device according to claim 9 in which the device is an organic light emitting diode.