Abstract
Lignin is one of the natural resources contained in coniferous trees up to 30% in weight, but it has not been utilized as a useful material up to now in contrast to the wide application of celluloses. Recently it was found that modification of the lignin with oligo-ethylene glycol gives "glycol-lignin" which is soluble in various solvent to open the door to practical applications. One of the application is the application to FRP matrix with combination of epoxy resin and DBU as a catalyst. However, a problem is that the polymerization starts before processing to harden the prepolymer because it must be heated about 100 °C for melting and mixing. Therefor those catalysts which are inactive below 100 °C but becomes active above 100 °C is desirable. We have developed thermal base generators, which were prepared by the neutralization of DBU as a strong basic initiator for epoxides with various acids such as a tetraphenylborate, phenolic resin, or phthalate. The DBU salts are inactive below 100 °C, but they generate free base upon heating above 160 °C thermal treatment to initiate hardening of epoxides. The base generating temperature was found to depend on the pKa of the counter cation of the thermal base generators, and the hardness of the hybrid materials reached as hard as 6H by pencil hardness measurement.
