| 摘要 |
PURPOSE:To prepare the powder improved in color development life by dissolving a polyolefin resin and a photochromic dye at a given wt. ratio in xylene, and then recovering the solvent with a vacuum dryer while at the same time obtaining the resulting particles in a dry state. CONSTITUTION:15-30 pts.wt. polyolefin resin, such as PE or PP, having a mol.wt. of 5,000 to 15,000, and 0.5-10wt.%, based on the resin, photochromic dye such as a spiropyran dye are added to and homogeneously dissolved in 100 pts.wt. xylene under stirring at a temp. of at most 110 deg.C. Thereafter, the temp. of the resulting soln. is dropped to at most about 80 deg.C. The soln. is then transferred to a vacuum dryer equipped with a stirrer, wherein it is dried under reduced pressure to simultaneously recover xylene. The resulting particles are pulverized with a jet pulverizer or the like to obtain a photochromic dye-contg. fine polyolefin resin powder having a particle size of at most 70mum and a color development life of 600 to 800hr. |
