Study On The Modifiers Of Insulation Paint Viscosity-thermal Index

In electrical insulation impregnation resin industry,there is a problem which is the viscosity of epoxy or unsaturated polyester decease rapidly when temperature rise.This character lead to resin waste a lot when cured in oven.Our study object is to find a suitable method or additive to reduce the viscosity decease when temperature rise from 30? to 70?.We use ?(the quotient of high and low temperature viscosity)to evaluate the viscosity-thermal performance of resin,and use Q(the viscosity-thermal index)to evaluate the viscosity additive performance.The ? and Q value depends on lots of factors,such as molecular weight,molecular shape,molecular polarity and additive kinds.Here we just focus on the molecular weight distribution,organic polymer additive and in-organic nanometer thixotropic agent.In molecular weight distribution study,we make different molecular weight distribution samples of unsaturated polyester and epoxy and test them.We find that the ? value increase when the polydispersity index increase on the condition of similar number-average molecular weight.By increase the polydispersity index,we elevate the ? value of epoxy from 0.02 to0.089,and the ? value of unsaturated polyester from 0.072 to 0.16.Organic polymer additives are some special high polymers which can extend their molecular chain in solvent when temperature rise and hinder viscosity decrease.The applicability is depend on the molecular structure and affinity to the base resin.We tested many different high polymers,and find the hydroxyl propyl cellulose can elevate the ? value of epoxy from 0.035 to 0.097,the Q value is 9.45,elevate the ? value of unsaturated polyesters from 0.124 to 0.173,the Q value is 2.24.Inorganic nanometer thixotropic agent include fumed silica,nanometer aluminum oxide and bentonite.The add quantity in test is 2%.For hydrogen bond effect,the viscosity show different value at different shear speed.In epoxy,the certain ratio of fumed silica and nanometer aluminum oxide mixture can elevate the ? value from 0.02 to 0.69 at 2 r/min and from 0.02 to 0.17 at 20 r/min,the corresponding Q value is 51.45 and 18.11.In unsaturated polyester,the special kind of hydrophilic fumed silica can elevate the ? value from 0.124 to1.66 at 2 r/min and from 0.124 to 0.78 at 20 r/min,the corresponding Q value is 23.95 and13.57.From study we find that the acting mechanism is nanometer particle separate from resin molecular when temperature rise and new hydrogen bond formed between nanometer particle which lead to viscosity-thermal performance increase.By compare the influence degree of all factors in this study,we find the first is the inorganic nanometer material,the second is the organic polymer additive and the third is molecular structure and molecular weight distribution.