| As a new type of thermosetting resin,bisphenol a cyanate ester has better mechanical properties,thermal stability,radiation resistance,flame retardancy,dielectric properties and less water absorption than traditional electronic bonding materials.It has a broad development prospect in the application of electronic components.However,the high curing temperature of ordinary cyanate adhesive limits its wide application in electronic industry.In order to prepare excellent cyanate esters at low curing temperature,this study prepared a series of modified cyanate copolymers via blending trace amounts of different phenolic compounds(approximately 1 wt%)with bisphenol a cyanate ester,respectively.In order to study the effect of phenolic hydroxyl content on the properties of cyanate ester,four modified cyanate ester adhesives were prepared by blending phenolic compounds(such as phenol,hydroquinonel,resorcinol and phloroglucinol)with cyanate ester.The results showed that the curing exothermic peak temperature(Tp)of all modified cyanate esters decreased by 16 °C ~ 35 °C,when compared to the unmodified cyanate ester.The analysis showed that the curing temperature of cyanate esters was mainly affected by the amount of phenolic hydroxyl groups and the reaction activity.Under the same curing process conditions,the modified cyanate ester has better dielectric properties,the dielectric loss value(Df)is between 0.0027 and 0.0028,the dielectric constant(Dk)is approximately 2.71 ~ 2.72.The dynamic mechanical analysis(DMA)showed that the lowest value of glass transition temperature(Tg)of cyanate esters was 287 °C,the highest value was 296.4 °C,which is 95% and 98% of unmodified cyanate,respectively.In addition,the tensile shear strength test results show that phenolic compounds with different hydroxyl content can enhance the bonding properties of cyanate.To investigate the effect of benzene ring resistance on the properties of cyanate ester in phenolic compound structure,bisphenol a cyanate ester was modified by monofunctional phenol(phenol,β-naphthol,and 1-anthrol)with different steric hindrance.DSC and FT-IR results showed that hydroxyphenol of monofunctional group could reduce the curing temperature of cyanate resin,and enhance the curing efficiency.The results of DMA tests showed that the thermal resistance of cyanate ester modified by 1-anthrachenol was the best,which is corresponding to 291.7 °C.Dielectric and tensile shear strength tests show that phenolic compounds of single functional groups can enhance the dielectric and adhesive properties of cyanate ester resin.Comparing the comprehensive properties of different cyanate ester systems,it is found that the modification effect of hydroquinone on cyanate ester resin is the best,and the modified cyanate ester has better curing conditions,thermal stability,heat resistance and adhesive properties. |
