Synthetic stone of high translucence, method of its production and use

Abstract

Stone is formed from 5 to 60% by weight of polymerised, low-viscosity, transparent or low-colour-resin, 20 to 90% by weight of spherical alumina trihidrate Al 2 O 3 .3H 2 O containing less regular particles containing, advantageously 0 to 100% by weight of a transparent or translucent substitute of alumina trihydrate, and/or with 0 to 20% or pre-prepared particulate, filled resin of a chosen colour, and/or mineral particles and less than 2% by weight of luminophor. These individual components are mixed intensely whilst extracting included gaseous parts. Extraction is carried out whilst mixing, and/or after mixing, and/or before mixing. The mixture is initiated by introducing a starter and intensely mixing it into the mixture. The mixture is poured into a mould or onto a moving endless belt. The cured synthetic stone is removed from the mould or the hardened composite is taken off the the belt. Synthetic stone can be used in products as a light carrier.

The invention claimed is: 
     
       1. A synthetic stone product which displays a light transmission through a 6 mm plate thereof at least of 22.5 to 53% and which comprises a hardened mixture of:
 (a) 5 to 60 wt % of a polymerized resin binder selected from the group consisting of methylmethacrylate and neopentylglycolic-polyester, said binder having a refractive index of light below 1300 mPas which varies less than 12% from 1.58, and 
 (b) 20 to 90 55.11 to 84.8 wt % of a filler comprising at least 68.6 68.8 to 85 wt % globular and/or spherical alumina trihydrate, Al 2 O 3 —3H 2 O Al 2 O 3 .3H 2 O, a surface area of the filler according to BET being less than BET 0.9 m 2 /g. 
 
     
     
       2. The synthetic stone product according to  claim 1 , wherein the binder resin has a viscosity of less than 100 mPas mPa·s. 
     
     
       3. The synthetic stone product according to  claim 1 , wherein the medium size of particles of the filler is greater than 15 μm and less than 200 μm. 
     
     
       4. A synthetic stone product with high translucence which comprises a hardened mixture of:
 (a) 5 to 60 wt % of a polymerized resin binder selected from the group consisting of methylmethacrylate and neopentylglycolic-polyester, and 
 (b) 20 to 90 wt % of a filler comprising consisting of globular and/or spherical styrene-divinylbenzene copolymer, a surface area of the filler according to BET being less than BET 0.9 m 2 /g. 
 
     
     
       5. The synthetic stone product according to  claim 4 , wherein the filler has a particle size less than 15 mm whose refractive index of light differs from the refractive index of light of alumina trihydrate by no more than ±12%. 
     
     
       6. The synthetic stone product according to  claim 4 , wherein the copolymer of styrene and divinylbenzene has a particle size ranging from 5 μm to 2000 μm. 
     
     
       7. The synthetic stone product according to  claim 6 , wherein the copolymer of styrene and divinylbenzenehas a particle size ranging from 100 μm to 400 μm. 
     
     
       8. A method of production of a synthetic stone product with high translucence according to claim  6  4, comprising the steps of:
 (a) mixing the polymerized binder and filler to form a mixture, 
 (b) pouring the mixture into a mold, 
 (c) curing the mixture in the mold, and 
 (d) removing the cured mixture as a synthetic stone product from the mold. 
 
     
     
       9. The synthetic stone product according to  claim 1 , wherein said filler comprises 70 wt % globular alumina trihydrate. 
     
     
       10. The synthetic stone product according to  claim 1 , wherein said filler comprises 68.8 wt % spherical alumina trihydrate. 
     
     
       11. The synthetic stone product according to  claim 1 , wherein said filler comprises 85 wt % globular alumina trihydrate. 
     
     
       12. The synthetic stone product according to  claim 4 , wherein said filler consists of globular and/or spherical styrene-divinlbenzene styrene-divinylbenzene copolymer. 
     
     
       13. The synthetic stone product according to claim 4, wherein the binder has a viscosity less than 100 mPa·s. 
     
     
       14. The synthetic stone product according to claim 4, wherein the surface area of the filler according to BET is less than 0.4 m 2 /g. 
     
     
       15. The synthetic stone product according to claim 1, wherein the surface area of the filler according to BET is less than 0.4 m 2 /g. 
     
     
       16. The method according to claim 8, wherein the polymerized binder has a viscosity of less than 1300 mPa·s. 
     
     
       17. The method according to claim 16, wherein the polymerized binder has a viscosity of less than 100 mPa·s. 
     
     
       18. A method of production of a synthetic stone product with high translucence according to claim 1, comprising the steps of:
 (a) mixing the polymerized binder and filler to form a mixture,   (b) pouring the mixture into a mold,   (c) curing the mixture in the mold, and   (d) removing the cured mixture as a synthetic stone product from the mold.   
     
     
       19. The method according to claim 18, wherein the polymerized binder has a viscosity of less than 1300 mPa·s. 
     
     
       20. The method according to claim 19, wherein the polymerized binder has a viscosity of less than 100 mPa·s.