| 摘要 |
<p>PROBLEM TO BE SOLVED: To effectively utilize an impregnating resin, by quickly and accurately deciding whether or not an acid anhydride composed of an epoxy resin and a setting agent of the acid anhydride can be used and a usable period of the impregnating resin. SOLUTION: The amount of a free acid promoting a polymerization reaction of an epoxy resin in an acid anhydride is obtained. More specifically, an absorbance A1 corresponding to a wavelength of 1775cm<-1> is obtained by an infrared spectrophotometer 9, and a concentration M1 of the free acid is obtained from a working curve L obtained by measuring an absorbance A of a sample 8 after changing a concentration M of the free acid of the acid anhydride hydrolyzed beforehand with a distilled water. The value is compared with a reference value, thereby to judge whether or not the acid anhydride is usable.</p> |
