Research On Silicone Pressure-sensitive Adhesive With High Temperature Resistance

As a special pressure-sensitive adhesive material,silicone pressure-sensitive adhesive has the advantages of good adhesion to high energy and low energy surfaces,high temperature resistance,no corrosion and no irritation.At present,the heat-resistant temperature of domestic silicone pressure-sensitive adhesive is generally around 200℃（good performance,no residual adhesive and no debonding）,which is much lower than the application temperature of electronic industry,so further improving the temperature resistance limit of silicone pressure-sensitive adhesive has great market value.In this research,by observing the residual behavior of unmodified silicone pressure-sensitive adhesive,the factors influencing the formation of residual adhesive were analyzed and explained.The dispersion of carboxylated MWNTs and potassium titanate whiskers in siloxane was improved by improving the addition method.Thus,0.2-1.0 phr rutile nano-Ti O₂,0.2-1.0 phr nano alumina,0.05-0.20 phr carboxylated MWNTs and 0-1.0 phr A-172 modified potassium titanate whisker were added.The high temperature resistance properties were compared by testing the residual temperature and the TG.Then the adhesive properties of the samples were compared by testing the ring initial adhesive force,holding adhesive force and180°peel strength.Considering the stickiness and high temperature resistance,the optimal proportion of each nano filler was obtained.Combined with the water contact angle and gel content of the sample,the reasons for the influence of nano filler on the properties of silicone pressure sensitive adhesive are analyzed,and the limitation of the physical modified silicone pressure sensitive adhesive is explained.Then,the chemical modification of POSS with reactive unsaturated group was attempted,and the formula of silicone pressure sensitive adhesive modified by vinyl POSS and allyl isobutyl POSS was designed according to the proportion of unsaturated group content.Through FTIR and gel content comparison,we have successfully prepared vinyl silicone POSS and grafted isobutyl POSS modified silicone pressure sensitive adhesive.The residual adhesive at high temperature,the holding force at high temperature and the thermogravimetric curve of these adhesives were compared.The changes of high temperature residual adhesive,high temperature viscosity and derivative peak of thermogravimetric analysis with the addition of modified POSS were determined.The initial adhesive force,180°peel strength and storage（consumption）modulus frequency diagram of the grafted isobutyl POSS were tested and were used to determine the variation of viscosity of silicone PSA samples modified by allyl isobutyl POSS.Combined with the contact angle test of the grinder film,the reason of the performance change is explained.Finally,the best addition amount of allyl isobutyl POSS which can ensure a certain viscosity and high temperature resistance was obtained.Finally,by comparing the transmittance and water absorption of nano filler modified and chemical modified samples,the advantages of chemical modified samples in transparency and aging resistance were shown.