High heat copolycarbonate compositions having enhanced optical properties, articles formed therefrom, and methods of manufacture

1. A thermoplastic composition comprising:

a copolycarbonate comprising 60 to 85 mol % of bisphenol A carbonate units and 15 to 40 mol % of second carbonate units each based on the total number of carbonate units in the copolycarbonate, the second carbonate units having the formula

wherein

R a and R b are each independently a C 1-12 alkyl, C 2-12 alkenyl, C 3-8 cycloalkyl, or C 1-12 alkoxy,

each R 3 is independently a C 1-6 alkyl,

R 4 is hydrogen, C 2-6 alkyl or phenyl optionally substituted with 1 to 5 C 1-6 alkyl groups,

p, q, and j are each independently 0 to 4; and

10 to 60 wt % of a bisphenol A homopolycarbonate based on the total weight of the thermoplastic composition;

wherein

the second carbonate units are present in an amount of 10 to 49 mol % based on the sum of the moles of the copolycarbonate and the bisphenol A homopolycarbonate,

the copolycarbonate comprises less than 2 ppm by weight of each of an ion of lithium, sodium, potassium, calcium, magnesium, ammonium, chlorine, bromine, fluorine, nitrite, nitrate, phosphite, phosphate, sulfate, formate, acetate, citrate, oxalate, trimethylammonium, and triethylammonium, as measured by ion chromatography, and

the thermoplastic composition has a bisphenol A purity of at least 99.6%, as determined by high performance liquid chromatography; and

wherein the thermoplastic composition has:

a Vicat B 120 softening temperature of 155° C. or higher as measured according to ISO 306; and

an increase in yellowness index of less than 10 during 1000 hours of heat aging at 155° C., as measured by ASTM D1925 on a 1 mm thick molded plaque.

2. A thermoplastic composition comprising:

a copolycarbonate comprising 60 to 85 mol % of bisphenol A carbonate units and 15 to 40 mol % of second carbonate units each based on the total number of carbonate units in the copolycarbonate, the second carbonate units having the formula

wherein

R a and R b are each independently a C 1-12 alkyl, C 2-12 alkenyl, C 3-8 cycloalkyl, or C 1-12 alkoxy,

each R 3 is independently a C 1-6 alkyl,

R 4 is hydrogen, C 2-6 alkyl or phenyl optionally substituted with 1 to 5 C 1-6 alkyl groups,

p, q, and j are each independently 0 to 4; and

10 to 60 wt % of a bisphenol A homopolycarbonate based on the total weight of the thermoplastic composition;

wherein

the second carbonate units are present in an amount of 10 to 49 mol %, based on the sum of the moles of the copolycarbonate and the bisphenol A homopolycarbonate,

the copolycarbonate comprises less than 2 ppm by weight of each of an ion of lithium, sodium, potassium, calcium, magnesium, ammonium, chlorine, bromine, fluorine, nitrite, nitrate, phosphite, phosphate, sulfate, formate, acetate, citrate, oxalate, trimethylammonium, and triethylammonium, as measured by ion chromatography, and

the thermoplastic composition has a bisphenol A purity of at least 99.6% as determined by high performance liquid chromatography; and

wherein

the thermoplastic composition has:

a Vicat B120 of 155° C. or higher as measured according to ISO 306; and

a yellowness index which is at least 20% lower compared to the same composition having a Bisphenol A purity below 99.6%, as measured by ASTM D1925 on a 2.5 mm thick molded plaque with a melt temperature of 355° C. and a residence time of 10 min.

3. The thermoplastic composition of claim 2 having an increase in yellowness index of less than 15 during 1000 hours of heat aging at 155° C., as measured by ASTM D1925 on a 1 mm thick molded plaque.

4. The thermoplastic composition of claim 1 , wherein

the second carbonate repeating units in the copolycarbonate are of the formula

wherein R 5 is hydrogen, phenyl or methyl.

5. The thermoplastic composition of claim 1 , wherein the copolycarbonate has less than 15 mol % of the second carbonate units directly coupled to another second carbonate unit, based on the total number of carbonate units in the copolycarbonate.

6. The thermoplastic composition of claim 1 ,

wherein the copolycarbonate further comprises at least 5 mol % of third carbonate units different from the bisphenol A carbonate units and the second carbonate unit, based on the total number of carbonate units in the copolycarbonate, the third carbonate units comprising carbonate units of the formula:

or a combination thereof, wherein

R c and R d are each independently a C 1-12 alkyl, C 2-12 alkenyl, C 3-8 cycloalkyl, or C 1-12 alkoxy,

each R 6 is independently C 1-3 alkyl or phenyl,

X a is a C 6-12 polycyclic aryl, C 3-18 mono- or polycycloalkylene, C 3-18 mono- or polycycloalkylidene, -(Q 1 ) x -G-(Q 2 ) y - group wherein Q 1 and Q 2 are each independently a C 1-3 alkylene, G is a C 3-10 cycloalkylene, x is 0 or 1, and y is 1, or —C(P 1 )(P 2 )— wherein P 1 is C 1-12 alkyl and P 2 is C 6-12 aryl, and

m and n are each independently 0 to 4, or a combination thereof.

7. The thermoplastic composition of claim 6 , wherein the third carbonate units have the formula

wherein

each R 1 is independently hydrogen or methyl,

each R 2 is independently methyl or hydrogen, and

g is 0 to 2.

8. The thermoplastic composition of claim 6 , wherein the copolycarbonate comprises from 15 to 70 mol % of the bisphenol A carbonate units, 5 to 50 mol % of the second carbonate units, and 5 to 50 mol % of the third carbonate units, each based on the total number of carbonate units in the copolycarbonate.

9. The thermoplastic composition of claim 1 , wherein the copolycarbonate has a hydroxyl end group content of less than 200 ppm and the optional bisphenol A homopolycarbonate has a hydroxyl end group content of less than 150 ppm.

10. The thermoplastic composition of claim 1 , wherein the copolycarbonate, the bisphenol A homopolycarbonate, or both are derived from a bisphenol A having a sulfur content of less than 2 ppm, each as measured by a Total Sulfur Analysis based on combustion and coulometric detection.

11. A thermoplastic composition comprising: 90 to 99.8 wt % of a copolycarbonate based on the total weight of the thermoplastic composition, the copolycarbonate comprising 60 to 85 mol % of bisphenol A carbonate units and 15 to 40 mol % of second carbonate units each based on the total number of carbonate units in the copolycarbonate, the second carbonate units having the formula

wherein

R a and R b are each independently a C 1-12 alkyl, C 2-12 alkenyl, C 3-8 cycloalkyl, or C 1-12 alkoxy,

each R 3 is independently a C 1-6 alkyl,

R 4 is hydrogen, C 2-6 alkyl or phenyl optionally substituted with 1 to 5 C 1-6 alkyl groups,

p, q, and j are each independently 0 to 4; and

optionally a bisphenol A homopolycarbonate based on the total weight of the thermoplastic composition;

wherein

the second carbonate units are present in an amount of 10 to 49 mol % based on the sum of the moles of the copolycarbonate and the bisphenol A homopolycarbonate,

the copolycarbonate comprises less than 2 ppm by weight of each of an ion of lithium, sodium, potassium, calcium, magnesium, ammonium, chlorine, bromine, fluorine, nitrite, nitrate, phosphite, phosphate, sulfate, formate, acetate, citrate, oxalate, trimethylammonium, and triethylammonium, as measured by ion chromatography, and

the thermoplastic composition has a bisphenol A purity of at least 99.6%, as determined by high performance liquid chromatography; and

wherein the thermoplastic composition has:

a Vicat B120 softening temperature of 155° C. or higher as measured according to ISO 306; and

an increase in yellowness index of less than 10 during 1000 hours of heat aging at 155° C., as measured by ASTM D1925 on a 1 mm thick molded plaque.

12. The thermoplastic composition of claim 1 , wherein the copolycarbonate is present in an amount of is 45 to 75 wt %, and the bisphenol A homopolycarbonate is present in an amount of 25 to 55 wt %, each based on the total weight of the thermoplastic composition.

13. The thermoplastic composition of claim 1 , further comprising 1 ppm to 40 ppm of an acid stabilizer, the acid stabilizer comprising a Bronsted acid, a Lewis acid, an acid or an ester thereof containing a sulfur atom, or a combination comprising at least one of the foregoing.

14. The thermoplastic composition of claim 13 , wherein the acid stabilizer comprises phosphoric acid; phosphorus acid; hypophosphorous acid; pyrophosphoric acid; polyphosphoric acid; an organo sulfonic stabilizer of the formula

wherein each R 7 is independently a C 1-30 alkyl, C 6-30 aryl, C 7-30 alkylarylene, C 7-30 arylalkylene, or a polymer unit derived from a C 2-32 ethylenically unsaturated aromatic sulfonic acid or its ester, and R 8 is hydrogen; or R 8 is C 1-30 alkyl; or R 8 is a group of the formula —S(═O) 2 —R 7 ; or a combination comprising at least one of the foregoing.

15. The thermoplastic composition of claim 1 , comprising, based on the total weight of the thermoplastic composition:

60 to 70 wt % of a copolycarbonate comprising bisphenol A carbonate units and second carbonate units of the formula

wherein R 5 is hydrogen, phenyl or methyl;

25 to 40 wt % of a bisphenol A homopolycarbonate; and

optionally 6 to 12 ppm of butyl tosylate;

wherein

the second carbonate units are present in an amount of 18 to 35 mol % based on the sum of the moles of the copolycarbonate and the bisphenol A homopolycarbonate,

the copolycarbonate comprises less than 2 ppm by weight of each of an ion of lithium, sodium, potassium, calcium, magnesium, ammonium, chlorine, bromine, fluorine, nitrite, nitrate, phosphite, phosphate, sulfate, formate, acetate, citrate, oxalate, trimethylammonium, and triethylammonium, as measured by ion chromatography, and

the thermoplastic composition has a bisphenol A purity of at least 99.7% as determined by high performance liquid chromatography; and

wherein the thermoplastic composition has:

an increase in yellowness index of less than 10 during 1000 hours of heat aging at 155° C., as measured by ASTM D1925 on a 1 mm thick molded plaque.

16. The thermoplastic composition of claim 11 , comprising, based on the total weight of the thermoplastic composition:

96 to 99.8 wt % of the copolycarbonate, the copolycarbonate comprising bisphenol A carbonate units and second carbonate units of the formula

wherein R 5 is hydrogen, phenyl or methyl; and

optionally 6 to 12 ppm of butyl tosylate;

wherein

the second carbonate units are present in an amount of 10 to 49 mol %, based on the sum of the moles of the copolycarbonate and the bisphenol A homopolycarbonate,

the copolycarbonate comprises less than 2 ppm by weight of each of an ion of lithium, sodium, potassium, calcium, magnesium, ammonium, chlorine, bromine, fluorine, nitrite, nitrate, phosphite, phosphate, sulfate, formate, acetate, citrate, oxalate, trimethylammonium, and triethylammonium, as measured by ion chromatography, and

the thermoplastic composition has a bisphenol A purity of at least 99.6% as determined by high performance liquid chromatography; and

wherein the thermoplastic composition has:

a Vicat B120 of 180° C. or higher as measured according to ISO 306; and

an increase in yellowness index of less than 10 during 1000 hours of heat aging at 155° C., as measured by ASTM D1925 on a 1 mm thick molded plaque.

17. The thermoplastic composition of claim 1 , wherein the thermoplastic composition has a yellowness index of less than 10 measured according to ASTM D1925 on a plaque of 2.5 mm thickness molded at a temperature of 355° C. for a residence time of 10 minutes.

18. The thermoplastic composition of claim 1 , further comprising a processing aid, a heat stabilizer, a colorant, a flame retardant, an impact modifier, an epoxy-containing polymer, or a combination thereof.

19. An article, wherein the article a molded article, a thermoformed article, an extruded film, an extruded sheet, one or more layers of a multi-layer article, a substrate for a coated article, or a substrate for a metallized article made from the composition of claim 1 .

20. The composition of claim 1 , wherein the composition is free of epoxy additives.