Composition and article for optical data storage devices

Abstract

Disclosed is an article for the optical storage of data having low birefringence prepared from a mixture of a polycarbonate and a cycloaliphatic polyester. The article may optionally have stabilization and mold release additives that retain transparency, color and processability.

What is claimed is:  
     
         1 . An article for optical storage of information comprising a blend of cycloaliphatic polyester and polycarbonate with in plane birefringence from −100 to +100 nm.  
     
     
         2 . An article for optical storage of information comprising a blend of cycloaliphatic polyester and polycarbonate with vertical birefringence less than or equal to 300×10-6.  
     
     
         3 . An article for optical storage of information comprising a blend of cycloaliphatic polyester and polycarbonate with stress optical coefficient (Cg) less than or equal to 70 Brewesters.  
     
     
         4 . An article of    claim 1    where the blend has % transmittance of greater than or equal to 75%.  
     
     
         5 . An article of    claim 1    where the blend has a glass transition temperature of from about 90 to 150° C.  
     
     
         6 . An article of    claim 1    where the blend further contains an effective amount of a stabilizer to prevent color formation.  
     
     
         7 . An article of    claim 6    where stabilizer is chosen from the group consisting of: phosphorus oxo acids, acid organo phosphates, acid organo phosphites, acid phosphate metal salts, acidic phosphite metal salts or mixture thereof giving an article with greater than or equal to about 75% transmittance.  
     
     
         8 . An article of    claim 6    where the yellowness index is less than or equal to about 5 YI units.  
     
     
         9 . An article of    claim 1    further comprising an effective amount of a mold release wherein the transmittance of the polycarbonate cycloaliphatic polyester blend is greater than or equal to about 75%.  
     
     
         10 . Article of    claim 9    wherein the mold release is pentaerythritol tetrastearate.  
     
     
         11 . An article of    claim 1    where the cycloaliphatic polyester is comprised of cycloaliphatic diacid and cycloaliphatic diol units.  
     
     
         12 . An article of    claim 11    where the polyester is polycyclohexane dimethanol cyclohexane dicarboxylate (PCCD).  
     
     
         13 . An article of    claim 1    where the polycarbonate is composed primarily of the following structural units: bisphenol A, spiro biindane bisphenol, an aryl substituted bisphenol, a cycloaliphatic bisphenol or mixtures thereof.  
     
     
         14 . An article of    claim 1    where the polycarbonate is BPA-PC and the cycloaliphatic polyester is PCCD.  
     
     
         15 . An article of    claim 1    where the ratio of cycloaliphatic polyester to polycarbonate in the blend is 40:60 to 5:95  
     
     
         16 . An article of    claim 1    which is a metal coated optical disc.  
     
     
         17 . An article of    claim 1    wherein the stored information can be read by a laser.  
     
     
         18 . An article for optical storage of information comprising a blend of a cycloaliphatic polyester and a polycarbonate wherein said polycarbonate comprises a spiro biindane bisphenol.  
     
     
         19 . An article for optical storage of information of    claim 18    wherein the cycloaliphatic polyester is comprised of cycloaliphatic diacid and cycloaliphatic diol units.  
     
     
         20 . A resin for molding optical quality articles comprising a blend of cycloaliphatic polyester and polycarbonate, wherein said resin blend has properties suitable for molding an optical quality article having in plane birefringence from −100 to +100 nm.  
     
     
         21 . A resin for molding optical quality articles comprising a blend of cycloaliphatic polyester and polycarbonate, wherein said resin blend has properties suitable for molding an optical quality article having vertical birefringence less than or equal to 300×10-6.  
     
     
         22 . A resin for molding optical quality articles comprising a blend of cycloaliphatic polyester and polycarbonate, wherein said resin blend has properties suitable for molding an optical quality article having a stress optical coefficient of less than or equal to 70 Brewsters.  
     
     
         23 . A resin for molding optical quality articles of    claim 20    wherein said blend has a glass transition temperature of from about 90 to 150° C.  
     
     
         24 . A resin for molding optical quality articles of    claim 20    wherein said blend further contains an effective amount of a stabilizer to prevent color formation.  
     
     
         25 . A resin for molding optical quality articles of    claim 24    wherein said stabilizer is chosen from the group consisting of: phosphorus oxo acids, acid organo phosphates, acid organo phosphites, acid phosphate metal salts, acidic phosphite metal salts or mixture thereof for making a molded article with greater than or equal to about 75% transmittance.  
     
     
         26 . A resin for molding optical quality articles of    claim 20    wherein said cycloaliphatic polyester is comprised of cycloaliphatic diacid and cycloaliphatic diol units.  
     
     
         27 . A resin for molding optical quality articles of    claim 20    wherein said polycarbonate is composed primarily of the following structural units: 
 bisphenol A, spiro biindane bisphenol, an aryl substituted bisphenol, a cycloaliphatic bisphenol or mixtures thereof.  
 
     
     
         28 . A process for molding optical articles comprising the steps of forming a resin blend of a blend of cycloaliphatic polyester and polycarbonate and molding an optical quality article having in plane birefringence from −100 to +100 nm.  
     
     
         29 . A process for molding optical articles comprising the steps of forming a resin blend of a blend of cycloaliphatic polyester and polycarbonate and molding an optical quality article having vertical birefringence less than or equal to 300×10-6.  
     
     
         30 . A process for molding optical articles comprising the steps of forming a resin blend of a blend of cycloaliphatic polyester and polycarbonate and molding an optical quality article having a stress optical coefficient less than or equal to 70 Brewsters.  
     
     
         31 . A process for molding optical articles of    claim 28    wherein said molding is carried out above the glass transition temperature of said resin blend, said resin blend having a glass transition temperature of from about 90 to 150° C.  
     
     
         32 . A process for molding optical articles of    claim 31    wherein said molding is carried out by injection molding.  
     
     
         33 . An article of    claim 1    which is an optical disc comprising at least one optical quality layer and means for encoding information from a signal, said optical quality layer comprising a blend of cycloaliphatic polyester and polycarbonate.  
     
     
         34 . A process for reading stored information on a disc of the type having at least one optical quality layer comprising transmitting a signal to said optical quality layer to read said stored information, said storing means being operably associated with said optical quality layer, said optical quality layer comprising a blend of cycloaliphatic polyester and polycarbonate with in plane birefringence from −100 to +100 nm.  
     
     
         35 . A process for reading stored information on a disc of the type having at least one optical quality layer comprising transmitting a signal to said optical quality layer to read said stored information, said storing means being operably associated with said optical quality layer, said optical quality layer comprising a blend of cycloaliphatic polyester and polycarbonate with vertical birefringence less than or equal to 300×10-6.  
     
     
         36 . A process for reading stored information on a disc of the type having at least one optical quality layer comprising transmitting a signal to said optical quality layer to read said stored information, said storing means being operably associated with said optical quality layer, said optical quality layer comprising a blend of cycloaliphatic polyester and polycarbonate with a stress optical coefficient of less than or equal to 70 Brewsters.  
     
     
         37 . A process for reading stored information on a disc according to    claim 34    wherein said signal comprises electromagnetic radiation from a laser.  
     
     
         38 . A process for reading stored information on a disc according to    claim 34    wherein said storage means comprises a plurality of surface depressions on said layer.