Preparation and performance of near-infrared absorption filtering films

Near infrared absorbing filtering films were prepared by melt mixing polymethylmethacrylate (PMMA) and near infrared absorbing dyes (NIR756 and NIR858). Thermal gravimetric analysis (TG) shows that the near infrared absorbing dyes have good thermal stability. The films have good near infrared absorption measured by the spectrophotometer. The average transmittances of 660 nm~930 nm are lower than 0.2%; the films also have high transmission tested by the spectrophotometer, the average transmittances of 400 nm~630 nm are higher than 20%. The films have good thermal aging properties. The dispersion of the near infrared absorbing dyes on the surface of the film is not even.