| 摘要 |
There is disclosed the use of solid blowing agents to generate polyimide foams which have low densities and identation load deflection (ILD) values and a relatively open cellular structure with larger cell sizes.
<??>The preferred method includes the steps of: preparing, foaming, and curing a precursor containing at least one alkyl ester of 3,3 min ,4,4 min -benzophenonetetracarboxylic acid; at least one of a meta- or para-substituted aromatic diamine and a heterocyclic diamine; and a solid blowing agent.
<??>Preferred heterocyclic and aromatic diamines are selected from the group consisting of:
2,6-diaminopyridine
3,5-diaminopyridine
3,3 min -diaminodiphenyl sulfone
4,4 min -diaminodiphenyl sulfone
4,4 min -diaminodiphenyl sulfide
3,3 min -diaminodiphenyl ether
4,4 min -diaminodiphenyl ether
meta-phenylene diamine
para-phenylene diamine
p,p min -methylene dianiline
2,6-diamino toluene
2,4-diamino toluene.
<??>Preferred blowing agents include:
toluene sulfonyl hydrazide
p,p min -oxybis (benzenesulfonyl hydrazide)
azodicarbonamide
p-toluenesulfonyl semicarbazide
hydrazole dicarboxylate
sodium bicarbonate
benzene sulfonyl hydrazide
triphenyl phosphate
sodium borate
borate acid
benzoic acid. |
