| The key to preparing precision texture injection molds is to replicate the original skin texture accurately with little loss of patterns during the process of reprinting and surface conduction treatment.Liquid addition silicone rubber with small volume shrinkage,fast curing and good deep curing ability,which is suitable for the preparation of the transfer pattern transfer model.Aiming to reduce the loss of patterns during the complex replicating and electricity conductive processing,this paper designs an electricity conductive silicone rubber with low processing viscosity and good operation performance,which avoid the surface conductive process.The formulation and curing process of the low-viscosity conductive silicone rubber were determined through the study of basic performance;the pattern loss rate at different latitudes was calculated by studying the characterization parameters of the pattern texture in depth,fullness and detail.The main research contents are as follows:Conductive polymers of polythiophene and polystyrene sulfonate?PEDOT:PSS?were prepared by redox method.When the ratio of EDOT to PSSNa was 1:2 and the pH value of sulfuric acid adjustment system was 1-1.5,the electricity conductivity of PEDOT:PSS can be acchieve 0.515 S/cm.PEDOT:PSS is used as conductive filler to prepare conductive silicone rubber and reprint model ESR.Compared with carbon black doped conductive silicone rubber CSR,the ESR shear viscosity is small and easy to operate.The shear viscosities of CSR-5?conductivity 66.46×10-66 S/cm?and ESR-20?conductivity 7.09×10-66 S/cm?with similar electrical conductivity are 45.7 Pa·s and 17.9 Pa·s,respectively.Loss rate in depth Pq of ESR-20 is 3.73%,loss rate in mirco-texture Pku is 6.42%,volume loss rate P is 4.24%,which is not as good as the reproduction model made of pure silicone rubber(Pq=2.74%,Pku=4.13%,P=2.56%).This is due to the weak binding force between polythiophene and silicone rubber,as a result the storage modulus of the overprint mold is low after complete curing,and the deformation resistance is poor,which affects its micro-morphology.Polythiophene/conductive carbon black doped conductive silicone rubber and reprint model ECR are prepared.When polythiophene content is 2 parts,the shear viscosity of silicone rubber is 29.46 Pa·s.The hardness of reprint model ECR-2 is 48.5 HA.The storage modulus of the system is high and the dimensional stability is good.There is no obvious aging phenomenon when the reprinted model is stored for a long time at the use temperature of 65°C.The loss rate in depth Pq of ECR-2 is 2.71%,loss rate in micro-texture Pku is 3.21%and volume loss rate P is 2.51%.The reprint effect of ECR-2 is better than pure silicone rubber reprint model(Pq=2.74%,Pku=4.13%,P=2.56%),this is because the deformation resistance of silicone rubber is improved by carbon black.ECR-2 can be used for the preparation of precision texture mold reprint models.The feasibility of polyaniline/conductive carbon black compound to prepare the conductive silicone rubber and reprint model was explored.Using 5 phr of conductive carbon black reinforced silicone rubber as the base matrix,the amount of polyaniline added as a variable to prepare conductive silicone rubber and reprint model ACR.By analyzing the shear viscosity,rheological properties,hardness,and conductive properties of the conductive silicone rubber ACR,it was determined that the shear viscosity,deformation resistance,and hardness can meet the requirements for preparing the reprint model.However,in terms of reprint effect,the texture detail and volume minimum loss rate of ACR are Pku=6.42%,P=5.75%,which is much greater than that of the reprint model ECR-2 and pure silicone rubber reprint model.The reprint effect is poor,indicating that the conductive silicone rubber ACR prepared in this experiment cannot used to prepare the reprint model of precision texture mold. |
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