| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyamic acid varnish which is prepd. by using a low- toxicity solvent, has a long pot life, and can form a thin film with a uniform thickness and without pinholes. SOLUTION: This varnish comprises 0.1-40wt.% polymer and 60-99.9wt.% solvent. The solvent is a mixture comprising 5-80wt.% compd. selected from among N-methyl-2-pyrrolidone, N-methylcaprolactam, N-methylpropionamoide, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, etc., and 20-95wt.% of at least one of cycloheptanone and methylcyclohexanone. |
