Multifunctional optically highly transparent films and method for their production

A multifunctional highly transparent film based on cellulose esters comprising:

• a) a cellulose triacetate or a mixture of cellulose triacetates derived from cotton linters forming a cellulose matrix, ≤300 ppm of birefringent particles with a size of ≤20 μm,
• ≤1% water,
• ≤300 ppm free acetic acid,
• ≤0,5% of gel forming components,
• a yellow coloration characterized by a Hazen-color APHA value ≤70, analyzed in a 16% solution of cellulose triacetate, dissolved in methyl chloride according to the method ASTM D-1209,
• ≤0,5% of foreign fibers, and cellulose derivatized particles of a size of ≤40 μm,
• b) an organic or inorganic substance which act as a distance holder between molecule chains of the cellulose ester and any residual solvents and acting as an agent for synergistically integrating additional additives into the matrix;
• c) at least three organic or inorganic light transmission reducing substances to reduce light that penetrate a film in the wave length range of 300 nm to 2500 nm, said substances acting as a plasticizer and as a distance holder between the molecule chains of the cellulose matrix,
• wherein the cellulose derivatized particles were dissolved in chloromethane or acetone and stretched into the film having a Haze value of ≤0.4%.