ANALYZING METHOD OF SAPONIFICATION VALUE IN EPOXY RESIN

摘要

PURPOSE:To analyze easily the saponification value in an epoxy resin with good accuracy by adding a standard KOH soln. and acetone soln. to a sample epoxy resin and heating the soln. to saponify completely the resin then titrating the soln. with a standard hydrochloric acid soln. CONSTITUTION:A sample epoxy resin is weighed into a round bottomed flask or the like and 0.5 normal standard KOH soln. is added to the sample then 67-75V/V% concn. acetone is added to the sample to prepare an epoxy resin soln. which does not produce white precipitate, etc. A reflux cooler is attached to the flask, etc. to boil the soln. for 1-2hr thereby saponifying completely the resin. A specified amt. of the saponified soln. is taken into a beaker and is titrated to appearance of a blue color by 0.5 normal hydrochloric acid soln. with thymolphthalein as an indicator. The saponification value of the sample is then calculated. The soln. is otherwise sampled into the prescribed vessel of an automatic titrator and is adjusted within 11.1+ or -0.2pH by a KOH soln. and hydrochloric acid soln. The end point of titration is exactly detected by a microcomputorized device. White precipitate is produced if pure water is used for cleaning in the case of transferring the saponified liquid into another vessel and therefore 71+ or -4V/V% acetone which is heated is used. The saponification value is thus measured with high accuracy.