| 摘要 |
PURPOSE:To obtain an indicator effective in clearly indicating the expiration of the guarantee period of a product without influencing the product and the environment by polymerizing a specific furan compound by the double bond in the ring without opening the 5-membered ring of the compound and using the obtained polymer as the indicator. CONSTITUTION:The objective indicator is composed of a polymer having a main chain containing the recurring unit of formula II and obtained by the cationic polymerization reaction of a compound of formula I (R<1> to R<6> are H or alkyl) in the presence of a polymerization initiator such as hydroiodic acid, chromium oxide or boron trifluoride preferably at a temperature between -100 deg.C and +50 deg.C. |
