Preparation And Properties Of Nano-sliver Conductive Ink Based On UV-Curing

Conductive ink is widely used in PCB, RFID antenna, sensors, solar cells, electronic paper and so on. The research on conductive ink contributes to the developments of the technology of printed electronics and makes electronics manufacturing industry highly efficient, low costly and friendly to the environment. It would improve the national economic efficiency. Now most of the conductive ink on the market is high temperature sintering and drying mode and the conductive silver paste is mostly micron silver powder. This has hindered the development of electronic printing industry because of conductivity and the way of drying. This paper is aimed to develop a UV light-cured nano-silver conductive ink in which the conductive filler is made up of the mixture of homemade spherical nano-silver and homemade flaky nano-silver, epoxy acrylate and self-made hyper branched polyurethane acrylate produced by prepolymer.Taking silver nitrate as precursor and hydrazine hydrate as reducing agent and PVP as dispersant and protection reagent, we use the method of dropping hydrazine hydrate into the mixture of silver nitrate and PVP to prepare silver nanoparticles. And the paper has analyzed the effect on average particle size of nano-silver caused by PVP amount, concentration of reductant and overall reactants. The best experimental condition for silver nanoparticles is confirmed. Malvern particle size graph and SEM images show that the experiment has prepared uniformly dispersed spherical nanometer with the average grain size of nearly 30 nm. The orthogonal experiment design L9(34) is used to study the effects of the amount of dispersant, reaction time,reaction temperature and stirring speed on the morphology and size of nano-silver. After that the best experimental condition to prepare flaky nano-silver is determined, and flaky nano-silver whose average grain size is 180 nm and diameter-thickness ratio is 9:1 is prepared.Starting from 2-hydroxyethyl methacrylate and isophorone diisocyanate to make polyurethane acrylate and starting from pentaerythritol and 2,2-dimethylol propionic acid to prepare hyper branched polyester polyol. Self-made polyurethane acrylate is used to have blocking reaction with hyper branched polyester polyol to produce a kind of new hyper branched polyurethane acrylate. Resaults showed that its glass transition temperature is low and the thermal stability is good. The glass transition temperature of HBPE-3 is 56.13℃ and the DB is 0.58. The glass transition temperature of the semi-crystalline HPUA-3 is 35.56℃, it’s cold crystallization temperature Tc is 110.92℃ and melting temperature Tm is 134.74℃.Select the mixture of spherical nano-silver powder and flake-shaped nano-silver as a conductive filler for ink, self-made hyperbranched polyurethane acrylate and epoxy acrylate as the prepolymer, TMPTA and NPGDA as the diluted monomers,(ITX + 173) as a photoinitiator agent, to formulate UV light curing nano-silver conductive ink. Experiment studies the impact of the prepolymer, monomer and photoinitiator agent on the ink light curing speed and viscosity, the experimental results show that when the ratio of the amount of monomer and prepolymer is 1: 1.5, and the epoxyacrylate and homemade overruns polyurethane acrylate is 2: 3,and the photoinitiator is 10% of the removed conductive silver ink amount, the ink light curing speed and viscosity achieve the best state, the light-curing time is only 6s,the ink adhesion test value is up to 2%. Analyzed the impact of the filling amount and morphology of nano-silver on the ink conductivity, the experimental results show that when the amount of silver filled at 60% and the ratio of the spherical nano-silver and the flake-shaped nano-silver is 3: 7, The resistivity of the ink is at 10-6Ω ? m orders of magnitude, the conductivity of the ink is higher than the current market of a number of levels of conductive ink.Using 400 mesh polyester silk net plate as the printing plate, using screen printing plate, experimental analysis of the relationship between the conductive properties of the ink and light curing time, under 375 W UV, the ink light curing time for optimum is 7s; Analyzed the ink adhesion from the appearance and scanning electron microscopy, it is concluded that the ink adhesion is high, the anti-tearing capacity is strong, and the resistance values has little difference after tearing; Experimental analysis of the relationship between the thickness and conductivity of the ink, with the increase of the thickness, the ink conductivity increases rapidly, and when the thickness is increased to 25 um, the ink conductivity will not be changed.This paper was prepared by orthogonal text method diameter to thickness ratio of 9: 1 sheet-shaped nano-silver, and with self-made spherical nano-silver by 7: 3 ratio as the ink conductive filler; Pentaerythritol and 2,2-dimethylol propionic acid(DMPA) as the raw materials for preparing the hyperbranched polyester polyol, using self-made Urethane acrylate for homemade hyperbranched polyester polyol capping reaction, to prepare a novel hyperbranched polyurethane acrylate, and with epoxy acrylate as the prepolymer of the ink. Experimental results show that the development of the high adhesion of the ink, light-curing time is short, the resistivity of an order of magnitude of up to 10-6Ω ? m. The drying method of traditional conductive ink which is sintering at high temperature is changed in this paper, and it has the advantages of green and environmental. The conductivity and printing performance will be improved significantly, and it has the important practical significance for the development of printed electronics technology.