The Researching Of Imaging Performance Declining Of Thermal Paper Which Is Containing Machannical Pulp

In order to solve the pratical problem of thermal paper with mechanical pulp developingimage performance declining efficiently and thoroughly. Based on the mutual influence ofmechanical pulp, chromogenic reagent, heat-sensitive dyes and thermal coating, and throughthe research of accelerated ageing and IR spectra analysis, the paper speculates fadingmechanism of thermal paper in theory, which provides powerful theoretical basis forthermal paper researchers to solve the pratical problemsIt is found out that the thermal base paper containing mechanical pulp can destroy thedeveloping image performance of thermal paper. The fundamental reason is that lignin in themechanical pulp will have chemical reactions with chromogenic reagent under certainconditions, which spoils the original image system and finally causes the declining ofdeveloping image function.A typical thermal chromogenic reagent often contains solid acid organism with phenolstructure. Phenolic hydroxyl group (R-OH)(Chromogenic functional group) and methoxygroup(-OCH3)(one of main functional groups in the lignin) can occur nucleophilicsubstitution under certain temperature and humidity conditions，so that the phenolichydroxyl R-OH reduces gradually and then loses the reaction activity.Thermalchromogenic reagent of different structures decides the reaction degree with the lignin.Whenactivity group R-OH in the chromogenic reagent exists the branch chain,the steric effect willincrease the reaction energy level between the methoxy and phenol hydroxyl (thatis, benzene ring electrophilic substitution effect). Therefore, it can show certain resistantlignin capacity.(developing image performance free or less by the mechanical pulp effects.)...