Synthesis And Property Investigation Of The Heat-sensitive Microcapsules

The heat sensitive microcapsule technology for information recording combines heat sensitive technology with microcapsule technology to prepare novel type of non-silver information recording materials with the properties such as quickly developing, high resolution, environment-protection and energy-saving. The heat developing properties, which can directly reflected the imaging quality of this material, are the most important character of heat sensitive microcapsule material.In this thesis, the preparation process of heat sensitive microcapsule was introduced. The interfacial polymerization method was applied to fabricate the sub-micrometre sized dye precursor microcapsules and developer microcapsules. Based on the analysis about the parameters such as the material function, synthesis technique and factors influencing the particle size distribution, the heat sensitive microcapsules with size of 0.1 to 1.5 micron and 10,20 micron were prepared.By the heat developing investigation processed in the temperature range from 100 to 150℃in the time scale of 0-10s, the heat image density properties of the microcapsules were studied. The relationship between image density and the developing conditions as well as the weight of microcapsule wall material were obtained. Results indicated that the image density could be affected by developing temperature, developing time and the weight of microcapsule wall material. Developing temperature determined the penetration ability of microcapsule wall, while developing time determined the image formation degree. The weights of microcapsule wall material affected the thickness of microcapsule wall and developing density. The optimal developing temperature was obtained as 130-140℃with the optimal developing time was 5 s. With the measurement of the image density change trend of the different particle sized microcapsules, it showed that the particle size of microcapsules had important impact on the image density. The larger the microcapsule size was, the lower the image density achieved. The optimal range of particle size was 0.5μm to 1μm.Through two different developer dispersion methods, one was the direct dispersion, while the other was the developer encapsulating form, the image density trend was roughly unchanged, though the image density of developer microencapsulating methods is less than the direct dispersion method. To achieve the same image density of the two dispersion method, D-8 with enough concentration was encapsulated in the microcapsules, then the image density reach the requirements of practical. The developer microencapsulating methods had the advantages to effectively reduce the fog in the material transportation, maintain the image stability of the applications of heat sensitive microcapsule material.The protective layer and the insulating layer, which was to improve the mechanical property as well as the waterproof, translucent property of heat sensitive microcapsule, were analyzed. The coating device of sliding funnel device, for the production of heat sensitive microcapsule and the optimum conditions to provides a basis for further research were obtained.