Light guide body having high luminous intensity and high transparency

Abstract

The present invention relates to light guide bodies having improved luminous intensity and transparency, to a method for their production and to their use.

1 . Light guide body having at least one light entry surface and at least one light emitting surface, 
 characterized in that    the ratio of the light emitting surface to the light entry surface is at least 4,    in that it has a haze, measured according to ASTM D1003, of less than 4%,    and in that titanium dioxide particles with an average particle size of 150-500 nm are used as light scattering means in a concentration of 0.1-100 wt·ppm, expressed in terms of the weight of the light guide body.    
     
     
         2 . Light guide body according to  claim 1 , 
 characterized in that    at least 50% of the titanium dioxide particles are present in the rutile modification.    
     
     
         3 . Light guide body according to  claim 1  or  2 , 
 characterized in that  
 the ratio of the light emitting surface to the light entry surface is at least 20.  
 
     
     
         4 . Light guide body according to one or more of the preceding claims, 
 characterized in that    it consists of the at least one transparent thermoplastic or thermoelastic plastic and/or in that it has light scattering means and a haze according to  claim 1  only in particular regions and/or in that it has regions which are not configured to be light-scattering.    
     
     
         5 . Light guide body according to one or more of the preceding claims, 
 characterized in that    titanium dioxide particles are used as light scattering means in a concentration of 0.1-50 wt·ppm, expressed in terms of the weight of the light guide body, preferably 0.1-10 wt·ppm, and/or in that the titanium dioxide particles have an average particle size of from 160 to 450 nm and particularly preferably from 170 to 400 nm, and/or in that the haze lies in the range of from 0.2 to 2%.    
     
     
         6 . Light guide body according to one of  claims 1  to  5 , 
 characterized in that  
 it does not have any printing and/or any light-scattering defects.  
 
     
     
         7 . Light guide body according to one or more of the preceding claims, 
 characterized in that    the light emitting surface is perpendicular to the light entry surface.    
     
     
         8 . Light guide body according to one or more of  claims 1  to  6 , 
 characterized in that  
 the light emitting surface is not perpendicular to the light entry surface and/or in that the shape is a freeform body.  
 
     
     
         9 . Light guide body according to one or more of the preceding claims, 
 characterized in that    the light guide body comprises at least 40 wt % of polymethyl methacrylate, preferably at least 60 wt %, expressed in terms of the weight of the light guide body.    
     
     
         10 . Method for producing a light guide body according to  claims 1  to  9 , 
 characterized in that  
 a light guide body is formed from a moulding compound having at least 40 wt % of polymethyl methacrylate, preferably at least 60 wt %, expressed in terms of the weight of the moulding compound, and from 0.1 to 100 wt·ppm of titanium dioxide particles, expressed in terms of the weight of the moulding compound, having an average diameter in the range of from 150 to 500 nm.  
 
     
     
         11 . Method for producing a light guide body according to one of  claims 1  to  9 , 
 characterized in that  
 an acrylic resin comprising  
 A) 0.1-100 wt·ppm of titanium dioxide particles having an average diameter in the range of from 150 to 500 nm,  
 B) 40-99.999 wt % of methyl methacrylate,  
 C) 0-59.999 wt % of comonomers,  
 D) 0-59.999 wt % of polymers soluble in (B) or (C),  
 the components A) to D) adding up to 100 wt %, is radical-polymerized and a light guide body is thereby obtained.  
 
     
     
         12 . Method for producing a light guide body according to one of claims  10  and  11 , 
 characterized in that  
 the shaped body is produced by casting methods, injection moulding, multicomponent injection moulding or by extrusion.  
 
     
     
         13 . Use of a light guide body according to one or more of  claims 1  to  9  as transparent glazing elements, which can be used as flat lights by switching on the light sources fitted on the light entry surfaces.  
     
     
         14 . Use of a light guide body according to one or more of  claims 1  to  9  as signs, display elements, advertising objects etc., which render particular symbols or signs visible only after switching on.