Near Infrared Absorbing Agent and Near Infrared Absorbing Film

Abstract

Disclosed herein is a method for preparing a near infrared absorbing agent. The method includes admixing tungsten trioxide and a reducing agent in water and allowing for a partial reduction of the tungsten trioxides to yield the near infrared absorbing agent.

1 . A near infrared absorbing film, comprising:
 a polyacrylic acid matrix; and   a plurality of near infrared absorbing agents distributed within the polyacrylic acid matrix, wherein the near infrared absorbing agents are prepared by a method comprising:   admixing tungsten trioxide and a reducing agent in water, wherein the tungsten trioxide has a chemical formula of WO 3 .H 2 O or WO 3 .2H 2 O; and   allowing a partial reduction of the tungsten trioxides in the water to proceed at a temperature of 0-100° C. and thereby yielding a reduced tungsten oxide as the near infrared absorbing agent, wherein the valence of the tungsten in the reduced tungsten oxide is from 5 to less than 6.   
     
     
         2 . The film of  claim 1 , wherein the film has a near infrared absorbance and a visible-light absorbance, and the near infrared absorbance is greater than the visible-light absorbance. 
     
     
         3 . The film of  claim 1 , wherein the film has an ultraviolet absorbance greater than the visible-light absorbance of the film.