Studies On The Preparation Of Water-based Adhesives In Photothermographic Material

Photothermographic material has been widely used in the field of diagnosis, microcopy and national defence because it doesn't need wet development process but the image with higher resolve and definition. But still it exists some disadvantages about PTG such as low sensitization, high fog value, the mechanism is not clear and so on.This paper was devoted to the study of the preparation of hydrophilic latex. Using styrene, butyl acrylate and acrylic acid as the monomers, a series of latex were prepared with the method of semi-continuance polymerization. In the end different technological conditions were discussed.It was found that initiator, emulsifier, temperature and other factors had important influence on the polymerization stability and the latex property. For example, higher conversion value can be obtained when the content of initiator is 0.4%. More dosage will lead to unstable reaction process and bad property of the latex; Low coagulation and small average diameter can be obtained if the amount of emulsifier is 5% and the ratio between SDS and OP-10 is 1:3, more dosage of emulsifier is disadvantageous; The most favorable reaction temperature is 80±2℃because higher temperature will accelerate the reaction velocity and lower temperature will expand the experiment period; When acrylic acid was adopted with the amount of 2%, not only the performance of the latex film was improved, but also the coagulation value was reduced; NaHCO₃ was adopted to maintain the constancy of pH value of the system because the decomposition of initiator can lead to the drop of the pH value which has negative effect towards the stability of the system, and the most suitable amount of it is 1～2%; Also it was showed that the agitator velocity should be kept separately at 150 r/min and 250 r/min or so during the beginning step and end step; The appropriate dropping velocity should be maintained at 10 drops per second.Through improving the technology of the emulsion polymerization, the latex which has solid contents approach to 45%, average diameter approximately 75nm was prepared. It provided a positive base for the further research of the latex which is suitable to be used in the PTG material.