Preparation Of UV-LED Curing Magnetic Anti-counte-Rfeiting Ink

At present,counterfeit and shoddy products on the market have brought huge damage to personal health.The development of anti-counterfeiting technology and anti-counterfeiting materials has received the attention of the government and researchers.Among the security materials,UV-LED magnetic anti-counterfeiting inks receive great attention because of the advantages of low VOC emission,high curing speed,deep color appearance,simple detection method,and excellent anti-counterfeit effect,and there is huge potential of development and application prospects in the field of green printing.In this paper,Fe₃O₄ nanoparticles were prepared by co-precipitation method,and coated with oleic acid.After being oxidized by acidic potassium permanganate solution,Fe₃O₄ nanoparticles with excellent magnetic properties were prepared.Finally,oleic acid modified magnetic Iron oxide particles and were used to preparation of UV-LED magnetic anti-counterfeit inks as magnetic pigments.The main contents of this paper include the following:Firstly,Fe₃O₄ magnetic nanoparticles with an average particle size of about 35 nm were prepared by using FeSO₄·7H₂O and FeCl₃·6H₂O as raw materials in co-precipitation method,and change the reactant concentration and reaction temperature to controlling the particle size and morphology of Fe₃O₄ nanoparticles successfully.The synthesized samples were characterized by X-ray diffractometry,scanning electron microscopy and vibrating sample magnetometer.The data showed that the samples were free from impurities and had high purity.The morphology was spherical and there was no obvious agglomeration.And the saturation magnetization of the samples are about 85.4 emu/g while the residual magnetization is about 9.2 emu/g that shows the typical characteristics of magnetic material.Secondly,oleic acid was used to coating the magnetic Fe₃O₄ nanoparticles,and then potassium permanganate solution was added to build a carboxyl to the surface of the Fe₃O₄ nanoparticles to prepare a carboxylated magnetic Fe₃O₄ nanoparticle with a particle size about 50 nm,stable magnetic properties,and excellent dispersibility in an organic solvent was prepared.The organic dispersion of modified magnetic Fe₃O₄ nanoparticles were characterized by settling distance.The experimental dates shows that the dispersion stability of the carboxyl modified magnetic Fe₃O₄ nanoparticles is significantly improved.Finally,self-made carboxylated Fe₃O₄ nanoparticles were used as magnetic pigments,epoxy-acrylate and dipropylene glycol diacrylate（DPGDA）mixtures were used as vehicle,2,4,6-trimethylbenzoyl-diphenylphosphine oxide（819）as photoinitiator to prepare UV-LED magnetic anti-counterfeit ink.After a large number of experiments and performance tests,the dates show the effects of the contents of magnetic pigments,photoinitiators and vehicle on the viscosity,magnetic response,curing speed,and abrasion resistance of the ink.After the formula was optimized based on the experimental data,the final formula of the UV-LED magnetic anti-counterfeiting ink was obtained:magnetic pigment content 40%～45%,11#vehicle content 45%～50%,photoinitiator 819 content 6%～7%,additives content 3%～4%.The ink has strong magnetic response,high curing speed,good anti-counterfeit effect and low VOC emission to be environmentally friendly.