Polymeric composition
The invention relates to a polymeric composition, comprising: at least one thermoplastic resin having a glass transition temperature of at least about 220° C.; inorganic particulates having an average particle size in the range up to about 100 nanometers dispersed in the thermoplastic resin, the inorganic particulates having an index of refraction in the range from about 1.4 to about 3; and an effective amount of at least one dispersant to disperse the inorganic particulates in the thermoplastic resin. The polymer composition may be a high temperature thermoplastic suitable for forming, such as by molding, optical articles such as lenses.
1. An additive composition for use with a thermoplastic resin having a glass transition temperature of at least 220° C. for making a molded article, comprising:
(a) at least one dispersant, the dispersant being thermally stable at a temperature of at least 350° C.;
(b) inorganic particulates having an average particle size in the range up to 100 nanometers, the inorganic particulates being thermally stable at a temperature of at least 400° C. and having an index of refraction in the range from 1.4 to 1.8; and
wherein the additive composition is thermally stable at a temperature of at least 400° C.;
wherein the inorganic particulates when combined with the thermoplastic resin form a dispersion with a zeta potential of at least +30 mV or more negative than −30 mV; and
wherein the molded article exhibits a luminous light transmission of at least 85% of the maximum theoretical value of the luminous transmission.
2. The composition of claim 1 wherein the composition further comprises one or more UV light stabilizers, heat stabilizers, antistatic agents, pigments, dyes, optical brighteners, flame retardants, melt processable glass reinforcing resin, or a mixture of two or more.
3. A method of making a polymer composition, comprising:
heating pellets of the thermoplastic resin at a temperature of at least about 70° C.; and
coating the pellets with the additive composition of claim 1 .
4. The composition of claim 1 wherein the composition further comprises at least one bluing agent.
5. The composition of claim 1 wherein the inorganic particulates are surface treated with one or more silanes or titanates.
6. The method of claim 3 wherein the thermoplastic resin comprises a polycarbonate.
7. The composition of claim 1 wherein the composition further comprises a primary antioxidant comprising a hindered phenol which is thermally stable at a temperature of at least about 400° C.
8. The composition of claim 1 wherein the composition further comprises a secondary antioxidant comprising a phosphite which is thermally stable at a temperature of at least about 400° C.
9. The composition of claim 1 wherein the inorganic particulates comprise aluminium oxide particulates.
10. The composition of claim 1 wherein the composition further comprises biphenol.
11. The composition of claim 10 wherein the biphenol is 4,4′ biphenol.
12. The composition of claim 1 wherein the molded article has a haze of less than about 3.
13. The composition of claim 1 wherein the molded article has a yellowness index of less than about 3.
14. The composition of claim 1 wherein the inorganic particulates are silane treated to enhance the dispersion of the inorganic particulates in the thermoplastic resin.
15. The composition of claim 1 wherein the inorganic particualtes are surface treated with one or more titanates, one or more zirconates, or a mixture thereof.
16. The composition of claim 1 wherein the dispersant comprises one or more fatty acids, fatty esters, fatty amides, fatty alcohols, silicones, polyalkylene glycols, or a mixture of two or more thereof.
17. The composition of claim 1 wherein the dispersant comprises one or more titanates, one or more zirconates, or a mixture thereof.