Back projection screen for LCD monitors comprises at least one light scattering polymethylmethacrylate layer containing spherical particles (A) and spherical particles (B) having different average particle sizes

摘要

A back projection screen comprises at least one light scattering polymethylmethacrylate layer comprising a polymethylmethacrylate matrix and spherical particles (A) and spherical particles (B) having different average particle sizes with at least one particle type having a refractive index that is different to that of polymethylmethacrylate matrix. A back projection screen (I) comprises at least one light scattering polymethylmethacrylate layer comprising a polymethylmethacrylate matrix and spherical particles (A) and spherical particles (B) having different average particle sizes whereby (A) have an average particle size of 0.1-40 mu m and a refractive index that is different to that of polymethylmethacrylate matrix by 0.02-2 and (B) have an average particle size of 10-150 mu m and a refractive index that is different to that of polymethylmethacrylate matrix by 0-0.2 and the total concentration of (A) and (B) is 1-60 wt. % (with respect to the light scattering polymethylmethacrylate layer) such that the ratio of the concentration of particles (A) CPA , thickness of the light scattering layer d s and particle size of (A) DPA as defined by CPA.ds/DPA3 is 0.001-0.015 wt.%.mm/mu m 3> and the corresponding ratio for particles (B), CPB.ds /DPB3 is 0.000005-0.002 wt.%.mm/mu m 3> and the ratio of the square of the average surface roughness of the polymethylmethacrylate layer R z to the cube of the particle size of (B) R 2> z/DPB3 is 0.0002-0.1300 mu m -> 1>. An independent claim is included for a process for the production of the screen (I) by extrusion of a composition comprising polymethylmethacrylate, particles (A) and particles (B).