Design And Performance Study Of UV Curable Cycloaliphatic Epoxy Resin System

In recent years,there has been an increasing demand for the toughness of thin-film packaging materials,with the development of flexible OLED displays.As an important UV curing epoxy resin,3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexylmethyl(TTA-21)has excellent processability,dielectric properties,thermal stability and adhesion,which makes it have a good application prospect in the field of electronic packaging.However,the cycloaliphatic epoxy resin has a rigid alicyclic structure and a higher crosslinking density of the cured product,which makes it more brittle and less flexible,so it is difficult to meet the development needs of flexible film packaging.In this paper,TTA-21 was modified by Bis((3,4-epoxycyclohexyl)methyl)adipate(TTA-26)and Trimethylolpropane triglycidyl ether(TPEG).The effect of photosensitizer 2-isopropylthioxanthone(ITX),benzoin dimethyl ether(BDK)and 1-hydroxycyclohexyl phenone(184)and their contents on curing behavior and light transmittance was systematically analyzed.Taking the tensile strength as the response value,the composition of the system was optimized by response surface analysis.In addition,Di(ethylene glycol)dimethacrylate(DEGDMA)and Triethylene glycol dimethacrylate(3EGDMA)are used to prepare TTA-21/DEGDMA and TTA-21/3EGDMA cation/radical hybrid UV curing films.The influence of the composition of the system on the mechanical properties,volume shrinkage,light transmittance and micro morphology of the cured film was fully explored.And evaluated the viscosity,surface tension and spreading performance of TTA-21/3EGDMA glue to provide reference for its application in inkjet printing and packaging process.The specific research work and main conclusions of this paper are as follows:(1)Using Triphenyl hexafluoroantimonate as the photoinitiator and 4-vinyl epoxy cyclohexane as the diluent,the effects of the type and amount of the photosensitizer on the curing degree and light transmittance of the TTA-21 film were explored.On this basis,the influence of TTA-26 and TPEG on the tensile strength of TTA-21 film was analyzed.The composition of the system was optimized by Box-Behnken response surface analysis.The results show that when the BDK content is 1%,the curing degree of the film is 98.12%,and the light transmittance is 86%.When the content of TTA-26 and PTEG is 20%,the tensile strength of the film is 46.80MPa and 42.78MPa,and the elongation at break is 11.2%and 13.7%,respectively;When the diluent content is 30%,the tensile strength of the cured film is 57.14MPa.The optimal composition of the system after optimization is:TTA-26 is 24.75%,TPEG is 20.65%,and diluent is 18.70%.Under this condition,the tensile strength of the film is 58.97MPa.(2)TTA-21/DEGDMA and TTA-21/3EGDMA films were prepared and modified by TPEG and GMA,and the influence of the system composition on mechanical properties,volume shrinkage,light transmittance and thermomechanical properties was explored.Compared with pure TTA-21,the composition of TTA-21/DEGDMA and TTA-21/3EGDMA was 1:1,the tensile strength of the film increased by 32.19MPa and 23.74MPa,and the elongation at break increased by 3.33%and 3.94%,respectively.TTA-21/3EGDMA has better toughness and low volume shrinkage,when the composition ratio of TTA-21/3EGDMA is 1:1,the KIC is 2.95MPa·m1/2,which increases by 85.76%,and the volume shrinkage rate is less than 5%.It has good toughness and low volume shrinkage rate.TPEG only improves the elongation at break of the film;GMA increases the Tg and cross-linking density of TTA-21/3EGDMA,and the light transmittance of the film is increased to more than 89.47%.(3)In order to further clarify the effect of GMA on the performance of TTA-21/3EGDMA,the content of GMA affects the tensile strength,fracture toughness,light transmittance,thermomechanical properties and microscopic morphology of TTA-21/3EGDMA,which has been comprehensively studied.When the GMA content is 20%,the tensile strength of the TTA-21/3EGDMA film with a composition ratio of 2:1 is 65.74MPa,and the elongation at break is 4.80%;when the GMA content was 40%,the Kic was 2.74 MPa.m1/2,an increase of 17.52%.The TTA-21/3EGDMA film transmittance of different GMA contents can reach more than 89.95%.With the addition of GMA increasing,the crosslink density of the cured material increased.When the addition of GMA was more than 30%,phase separation occurred,which increased the flexibility of the film,and the microstructure was confirmed to be ductile fracture.(4)Finally,the application parameters of the gel were investigated,and the viscosity,surface tension and spreading properties of the TTA-21/3EGDMA were tested.The results show that the diluent can adjust the viscosity and surface tension of TTA-21/3EGDMA glue effectively.Under the working temperature of 45? and long-term storage at room temperature,the viscosity of the glue always keeps the same as the initial viscosity.When the wetting agent is added,the contact angle of the glue decreases from 16.70 to 6.0°,and the spreading performance increases from 13.71%to 38.67%.