Laser Holographic Embossed Recording Material Based On Fluorinated Polyacrylate

Laser holographic embossed materials have been increasingly applied as anticounterfeiting products due to their difficulty to forge and high efficiency.Thermoplastic polyacrylate is generally used for recording and transferring holograms in the embossed materials.However,the polyacrylate always exhibits strong adhesion to the nickel plate.Consequently,it is hard to separate the embossed polyacrylate with nickel master without reducing the quality of holograms.To avoid strong adhesion of polyacrylate to metal plate,surface modification of polyacrylate via blending with polytetrafluoroethylene(PTFE)micropowder for anti-adhesive performance has been employed.Nevertheless,the low surface energy of PTFE leads to inherently poor adhesion and compatibility with polyacrylate.To solve this problem,surface modification including chemical etching with sodium naphthalene and insitu irradiation-induced grafting is a good way.In this thesis,poly(methyl methacrylate)grafted PTFE micropowder(PMMA-g-PTFE)is prepared by in-situ irradiation-induced grafting polymerization and then incorporated into polyacrylate matrix to fabricate composite films.The relationships between monomer concentration and irradiation dose with degree of grafting have been discussed.The results show that the compatibility of PTFE micropowder with polyacrylate has been improved due to grafting PMMA chains.Especially,it is found that the use of fluorosurfactant hinders the homopolymerization of monomers.The PMMA-g-PTFE micropowder with 17.8% degree of grafting is best for good dispersion and interfacial action in polyacrylate.Finally,according to the water contact angles of polyacrylate/PMMA-g-PTFE composite films,it is concluded that optimal micropowder loading is 14 wt% while holding a good surface roughness and the water contact angle increases by 21.1% to 94.0?.Next,chemical etched PTFE micropowder with sodium naphthalene(Na-Naph-PTFE)is also incorporated into polyacrylate resin to decrease its surface energy.Similarly,the influences of etching solution concentration and etching time on the chemical composition and micromorphology of micropowder surface are studied.Although the drastical decrease of fluorine atoms and increase of oxygen atoms are founded in Na-Naph-PTFE micropowder prepared in etching solution of higher concentration or at longer etching time,the excess etching will cause too much carbonization and aggregation of micropowder,leading to poor dispersion and adhesion in polyacrylate.The Na-Naph-PTFE micropowder prepared in 0.4 mol/L etching solution for 5 min has less fluorine atoms and more oxygen-containing chains which are benefit for better dispersion in polyacrylate.Thus,it is optimal to enhance the surface property of polyacrylate composite films.As expected,the water contact angles of polyacrylate composite films increase with Na-Naph-PTFE micropowder loading,despite of less obvious improvement effect on surface hydrophobicity than PMMA-g-PTFE micropowder.By comparing these two surface modification methods,it can be concluded that in-situ irradiation-induced grafting polymerization has better control and generated micropowder has more significant effect on the surface property of polyacrylate composite films.While chemical etching with sodium naphthalene solution can introduce more oxygen-containing chains into PTFE.Therefore,it is necessary to modify fluoropolymers for varied applications with appropriate method.Furthermore,the generating new composite films with lower surface energy can reduce the adhesion between polyacrylate and nickel master and pave the way for embossed holography.