Modification, Structure And Properties Of Embossing Holographic Recordingmaterials For Anti-counterfeiting

Laser holographic technology as acurrent anti-counterfeiting technique has played an important role in the fight against fake and shoddy behaviors. However, the poor thermal resistance and abrasion performance of the holographic recording materials limit their applications in some advanced fields, such as national certification, diplomaticpassport, currency, and financial cards. In this dissertation, the commercial embossing holographic recording material, polyacrylate (PAE) named as Doresco(?)AC341-2, was modified to improve the thermal resistance, abrasion performance, embossing and hot-stamping properties by compositing or blending. The main research contents and results are as follows:(1) The nanosilica (SiO2) modified PAE coatings were prepared through physical mixing and in situ sol-gel process, respectively. Compared to physical mixing, the in situ sol-gel process can generate nanoscale SiO2particles which are homogeneously dispersed in the PAE matrix. The PAE/SiO2nanocomposite films still show excellent transparency even when the SiO2content reaches as high as25wt%. The light transmittances of all composite films are over85%, near to the value of pure PAE coating. The glossiness values of all composite films are over60Gs, and they show a rise tendency with the increase of SiO2content. However, their hardness and glossiness residueincrease firstly and decrease subsequently with the SiO2content increasing. And the PAE/SiO2composite film has a maximum of hardness and optimal anti-abrasion performance when the nano-SiO2content reaches to10wt%.(2) The PAE/titaniumdioxide (TiO2) nanocomposite coatings were prepared through in situ sol-gel process. The amorphous nano-TiO2particles are also uniformly dispersed in PAE matrix. The PAE/TiO2nanocomposite coatings show the same light transmittance as the PAE/SiO2nanocomposite coatings fabricated by in situ sol-gel process. The glass transition temperature (Tg) values of the PAE/TiO2nanocomposite films rises with the increase of the nano-TiO2loading. The Tg reaches118℃after the nano-TiO2content increases to20wt%, which the thermal resistance of the composite film is improved. The uniformly dispersed nano-size TiO2increases the glossiness of the PAE/TiO2nanocomposite films. High refractive index of nano-TiO2endows the PAE/TiO2nanocomposite films obviously higher glossiness than PAE/SiO2nanocomposite films. Every holographic gratingformed with PAE/TiO2nanocomposite films has diffraction efficiency over1.5, which is significantly higher than those of PAE/SiO2nanocomposite gratings.(3) The uniformly dispersed polyacrylate/octabutyl polyhedral oligomericsilsesquioxane (OBPOSS) composite coatings were prepared by physical mixing. They show the Newtonian fluid behavior, and their viscosity values decrease with the OBPOSS content increasing.However, the Tg values of the PAE/OBPOSS composite films rise with the increase of OBPOSS loading.Transparence of the PAE film is hardly affected by adding OBPOSS. The PAE/OBPOSS composite films have almost the same light transmittance as pure PAE filmeven if the OBPOSS content arrives to25wt%.The PAE/OBPOSS composite films also show high glossiness, which nearly keep constant when the OBPOSS content varies. The OBPOSS increases the toughness of the PAE coating as well as improves the molding performance of the PAE/OBPOSS composite film. When the OBPOSS content is10wt%, the PAE/OBPOSS composite film presents an optimal overall performance.(4) The PAE/polytetrafluoroethyle (PTFE) blend coatings were also prepared with2～3μmPTFE micropowders by physical mixing. Adding PTFE micropowders increases the viscosity of PAE/PTFE blend coatings. The fabricated PAE/PTFE blend films presents an excellent surface without sagging and/or floating defects when1.0-1.5wt%of PTFE micropowders are added into PAE. The addition of PTFE micropowders decreases the glossiness and toughness of PAE/PTFE blend films. However, the glossiness values of PAE/PTFE blend films containing1.0-1.5wt%of PTFE micropowders are still over100Gs, and the films look smooth and tactile appeal, which can meet the glossiness requirementof holographic recording materials. And this PAE/PTFE blend film expresses the optimal molding and hot-stamping properties because its surface tension is reduced and toughness is moderately decreased.