Transparent articles prepared from thermoplastic compositions having low birefringence

1. An optical grade article comprising a thermoplastic composition comprising a poly(aliphatic ester)-polycarbonate copolymer comprising the following monomeric units:

10 to 25 wt % of a soft block ester unit derived from a C 20-44 aliphatic dicarboxylic acid or derivative thereof,

34 to 77 wt % of a carbonate unit derived from 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine,

0 to 76 wt % of a carbonate unit derived from a dihydroxyaromatic compound excluding 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine, and wherein the sum of the weight percentages of soft block ester units, 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine units, and dihydroxyaromatic compound units is 100 weight percent of the monomeric units of the poly(aliphatic ester)-polycarbonate, and

wherein the refractive index of the thermoplastic composition is greater than or equal to 1.590, and the glass transition temperature of the copolymer is from 120 to 155° C.

2. The optical grade article of claim 1 , comprising the following monomeric units:

10 to 25 wt % of the soft block ester unit, and

34 to 75 wt % of the carbonate unit derived from 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine, and

0 to 58 wt % of the carbonate unit derived from a dihydroxyaromatic compound excluding 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine,

wherein the sum of the weight percentages of soft block ester units, 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine units, and dihydroxyaromatic compound units is 100 weight percent of the monomeric units of the poly(aliphatic ester)-polycarbonate.

3. The optical grade article of claim 1 , the poly(aliphatic ester)-polycarbonate comprising the following monomeric units:

11 to 21 wt % of the soft block ester unit,

34 to 53 wt % of the carbonate unit derived from 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine, and

33 to 58 wt % of the carbonate unit derived from a dihydroxyaromatic compound excluding 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine,

wherein the sum of the weight percentages of soft block ester units, 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine units, and dihydroxyaromatic compound units is 100 weight percent of the monomeric units of the poly(aliphatic ester)-polycarbonate.

4. The optical grade article of claim 1 , wherein the poly(aliphatic ester)-polycarbonate copolymer has a weight average molecular weight of 10,000 to 25,000 g/mol, when measured by gel permeation chromatography using a crosslinked styrene-divinylbenzene column calibrated to polycarbonate standards.

5. The optical grade article of claim 1 , wherein the thermoplastic composition has a melt volume rate of 13 to 25 cc/10 min at 250° C. and under a load of 1.2 kg and a dwell time of 4 minutes, according to ISO 1133.

6. The optical grade article of claim 1 , wherein the soft block ester units are derived from a branched aliphatic dicarboxylic acid of formula (9f):

wherein m and m′ are independently 0 to 38, n and n′ are independently 0 to 38, and the sum m+m′+n+n′ is an integer from 14 to 38.

7. The optical grade article of claim 1 , wherein the C 20-44 aliphatic dicarboxylic acid comprises C 36 aliphatic dicarboxylic acid, C 44 aliphatic dicarboxylic acid, or a combination comprising at least one of the foregoing.

8. The optical grade article of claim 1 , wherein the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine has the formula (8):

wherein R i , R j , and R k are independently C 1-12 hydrocarbyl, G is a C 1-12 alkyl or C 6-18 aromatic group, and u, v, and w are each independently an integer from 0 to 4.

9. The optical grade article of claim 8 , wherein the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine is 2-phenyl-3,3-bis(4-hydroxyphenyl)phthalimidine, having the formula (8a):

10. The optical grade article of claim 1 , wherein the dihydroxyaromatic compound comprises bisphenol A, bis(3-methyl-4-hydroxyphenyl)cyclohexane, or a combination comprising at least one of the foregoing.

11. The optical grade article of claim 1 , wherein the thermoplastic composition when molded into an article having a thickness of 3.2 mm, has a haze of less than or equal to 1.0 percent, when measured according to ASTM D1003-00.

12. The optical grade article of claim 1 , wherein the thermoplastic composition when molded into an article having a thickness of 3.2 mm, has a transmittance of greater than or equal to 85 percent, when measured according to ASTM D1003-00.

13. The optical grade article of claim 1 , wherein the thermoplastic composition, when molded into an article having a thickness of 3.2 mm, has a yellowness index (YI) of less than 4, when measured according to ASTM D1925-70.

14. The optical grade article of claim 1 , wherein the birefringence of a plaque having a thickness of 1.2 mm and molded from the thermoplastic composition at a barrel temperature of 300° C. and a mold temperature of 100° C. has a comparative average birefringence measured by polarized light microscope using the Michel-Levy birefringence scale of less than or equal to 300 nanometers.

15. The optical grade article of claim 1 , wherein the intrinsic birefringence of a film of the poly(aliphatic ester)-polycarbonate, having a thickness of 250 to 500 nm, and rubbed the point of saturation, is less than or equal to 0.015.

16. The optical grade article of claim 1 , wherein the thermoplastic composition further comprises a polycarbonate.

17. The optical grade article of claim 16 , wherein the thermoplastic composition comprises 50 to 99 wt % poly(aliphatic ester)-polycarbonate, and 1 to 50 wt % polycarbonate, based on the total weight of poly(aliphatic ester)-polycarbonate and any added polycarbonate.

18. The optical grade article of claim 1 , wherein the optical grade article is a camera lens, goggle lens, light guide, an imaging medium, or transparent bezel.

19. An optical grade article comprising a thermoplastic composition comprising a poly(aliphatic ester)-polycarbonate copolymer comprising:

10 to 21 wt % of soft block ester units derived from an alpha, omega C 20-44 aliphatic dicarboxylic acid or derivative thereof,

34 to 53 wt % of a carbonate unit derived from 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine,

34 to 58 wt % of a carbonate unit derived from a dihydroxyaromatic compound not identical to the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine,

wherein the sum of the weight percentages of the soft block ester units, 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine units, and dihydroxyaromatic compound units is 100 weight percent of the monomeric units of the poly(aliphatic ester)-polycarbonate,

wherein the thermoplastic composition when molded into an article having a thickness of 3.2 mm, has a haze of less than or equal to 1.0 percent, when measured according to ASTM D1003-00,

wherein the refractive index of the thermoplastic composition at a mold temperature of 100° C. is greater than 1.590, and the glass transition temperature of the poly(aliphatic ester)-polycarbonate is from 135 to 140° C.

20. A camera lens comprising a thermoplastic composition comprising:

a) a poly(aliphatic ester)-polycarbonate copolymer comprising the following monomeric units:

10 to 25 wt % of soft block ester units of the formula (9e):

wherein m and m′ are independently 0 to 38, n and n′ are independently 0 to 38, and the sum m+m′+n+n′ is an integer from 14 to 38;

34 to 77 wt % of a carbonate unit derived from 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine, and

0 to 76 wt % of a carbonate unit derived from a dihydroxyaromatic compound not identical to the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine,

wherein the sum of the weight percentages of soft block ester units, 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine units, and dihydroxyaromatic compound units is 100 weight percent of the monomeric units of the poly(aliphatic ester)-polycarbonate, and

b) optionally, a polycarbonate,

wherein an article molded from the thermoplastic composition and having a thickness of 3.2 mm has a haze of less than or equal to 1.0 percent, when measured according to ASTM D1003-00,

wherein the refractive index of the thermoplastic composition is greater than or equal to 1.590, and wherein the camera lens having an effective lens area of 0.5 mm 2 to 100 mm 2 and molded from the thermoplastic composition at a barrel temperature of 300° C., and measured for birefringence by the parallel Nicols method at a wavelength of 590 nm, has a birefringence of less than or equal to 90 nanometers.

21. The camera lens of claim 20 , having an effective lens area of 0.5 to 10 mm 2 .

22. The camera lens of claim 20 , wherein the camera lens thickness is from 0.25 to 2.5 mm.

23. An imaging apparatus comprising a light proof housing, wherein said housing contains a light transmission medium containing an optical grade article of claim 1 , a shutter, a shutter control vehicle, and an imaging substrate.

24. A camera lens comprising a thermoplastic composition comprising:

a) a poly(aliphatic ester)-polycarbonate copolymer comprising the following monomeric units:

10 to 25 wt % of soft block ester units of the formula (9e):

wherein m and m′ are independently 0 to 38, n and n′ are independently 0 to 38, and the sum m+m′+n+n′ is an integer from 14 to 38;

34 to 77 wt % of a carbonate unit derived from 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine, and

0 to 76 wt % of a carbonate unit derived from a dihydroxyaromatic compound not identical to the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine,

wherein the sum of the weight percentages of soft block ester units, 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine units, and dihydroxyaromatic compound units is 100 weight percent of the monomeric units of the poly(aliphatic ester)-polycarbonate, and

b) a BPA polycarbonate

wherein an article molded from the thermoplastic composition and having a thickness of 3.2 mm has a haze of less than or equal to 1.0 percent, when measured according to ASTM D1003-00,

wherein the refractive index of the thermoplastic composition is greater than or equal to 1.590, and wherein the camera lens having an effective lens area of 0.5 mm 2 to 100 mm 2 and molded from the thermoplastic composition at a barrel temperature of 300° C., and measured for birefringence by the parallel Nicols method at a wavelength of 590 nm, has a birefringence of less than or equal to 90 nanometers.