Ionizing radiation stable thermoplastic composition, method of making, and articles formed therefrom

1. A thermoplastic composition comprising:

a polycarbonate, and

an aromatic sulfonate compound of formula

(Y) m —Ar—(Z—S(O) 2 —X) n

wherein

each X is independently a substituted or unsubstituted C 1 -C 20 alkyl, substituted or unsubstituted C 1 -C 20 arylalkyl, substituted or unsubstituted C 6 -C 20 aryl, or substituted or unsubstituted C 7 -C 40 alkylaryl,

Z is —O—or substituted or unsubstituted —(—O—C 1-20 —) w —O—, wherein w is 1 to 20,

Ar is a C 6 -C 62 aromatic group; m is 0-3 and n is 3-6; and

each Y is independently C 1 -C 20 alkyl, substituted C 1 -C 20 alkyl, C 6 -C 20 aryl, C 1 -C 8 alkyl-substituted C 6 -C 20 aryl, halogen, nitro, C 1 -C 20 alkoxycarbonyl, C 1 -C 20 alkoxy, or C 1 -C 20 acyl, and

a ionizing radiation stabilizing additive,

wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of the polycarbonate, aromatic sulfonate compound, and an effective amount of each of a mold-release agent and an antioxidant has, after exposure to a total gamma radiation dose of 83 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 45, when compared to the unexposed molded article.

2. The thermoplastic composition of claim 1 , comprising 0.001 to 500 mmol/Kg of the aromatic sulfonate compound, based on the total weight of the polycarbonate and aromatic sulfonate compound.

3. The thermoplastic composition of claim 1 , comprising 0.001 to 5 mmol/Kg of the aromatic sulfonate compound, with the proviso that the amount of aromatic sulfonate compound does not exceed 0.5 wt% of the total weight of the polycarbonate and aromatic sulfonate compound.

4. The thermoplastic composition of claim 1 , wherein Ar is a C 6 aromatic group having a valency of m+n, and wherein m+n is 6.

5. The thermoplastic composition of claim 4 , wherein at least two of the —Z—S(O) 2 —X groups are substituted ortho to each other on the C 6 aromatic group.

6. The thermoplastic composition of claim 1 , wherein the ionizing radiation stabilizing additive is an aliphatic alcohol, an aromatic alcohol, an aliphatic diol, an aliphatic polyol, an aliphatic ether, an ester, a diketone, an alkene, a thiol, thioethers, a cyclic thioether, a sulfone, a dihydroaromatic, a diether, a nitrogen compound, or a combination comprising at least one of the foregoing.

7. The thermoplastic composition of claim 6 wherein the aliphatic diol has the structure:

HO—(C(A′)(A″)) c —S—(C(B′)(B″)) d —OH

wherein A′, A″, B′, and B″ are each individually H or C 1 -C 6 alkyl; and wherein S is C 1 - C 20 alkyl, C 2 -C 20 alkyleneoxy, C 3 -C 6 cycloalkyl, or C 3 -C 6 substituted cycloalkyl; and wherein c and d are each 0 or 1, with the proviso that, where c and d are each 0, S is selected such that both —OH groups are not connected directly to a single common carbon atom.

8. The thermoplastic composition of claim 6 , wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of polycarbonate, aromatic sulfonate compound, aliphatic diol, and an effective amount of each of a mold release agent and an antioxidant has, after exposure to a total gamma radiation dose of 83 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 29, when compared to the unexposed molded article.

9. The thermoplastic composition of claim 6 , wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of polycarbonate, aromatic sulfonate compound, aliphatic diol, and an effective amount of each of a mold-release agent and an antioxidant has, after exposure to a total gamma radiation dose of 59 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 9, when compared to the unexposed molded article.

10. The thermoplastic composition of claim 6 , wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of polycarbonate, aromatic sulfonate compound, aliphatic diol, hydrolysis stabilizer, and an effective amount of each of a mold-release agent and an antioxidant has, after exposure to a total gamma radiation dose of 32 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 5, when compared to the unexposed molded article.

11. The thermoplastic composition of claim 6 , further comprising a hydrolysis stabilizer, wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of polycarbonate, aromatic sulfonate compound, aliphatic diol, hydrolysis stabilizer, and an effective amount of each of a mold-release agent and an antioxidant has, after exposure to a total gamma radiation dose of 83 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 35, when compared to the unexposed molded article.

12. The thermoplastic composition of claim 11 , wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of polycarbonate, aromatic sulfonate compound, aliphatic diol, hydrolysis stabilizer, and an effective amount of each of a mold-release agent and an antioxidant has, after exposure to a total gamma radiation dose of 51 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 13, when compared to the unexposed molded article.

13. The thermoplastic composition of claim 1 , further comprising an impact modifier, filler, antioxidant, heat stabilizer, light stabilizer, ultraviolet light absorber, plasticizer, mold release agent, lubricant, antistatic agent, pigment, dye, flame retardant, anti-drip agent, or a combination comprising at least one of these.

14. The thermoplastic composition of claim 13 wherein the pigment is Pigment Blue 15:4, Pigment Blue 28, or a combination comprising at least one of the foregoing.

15. The thermoplastic composition of claim 1 wherein the aromatic sulfonate compound is 1,3,5-tri-(4-toluenesulfonyl) benezene, 1,2,3-tri-(4-toluenesulfonyl) benezene, 1,2,3-tri-(4-acetylbenzenesulfonyl) benezene, 1,2,3-tri-(4- tmethoxybenzenesulfonyl) benezene, 1,2,3-tri-(n-octanesulfonyl) benezene, or a combination comprising at least one of the foregoing.

16. A thermoplastic composition comprising:

a polycarbonate, and

0.001 to 500 mmol/Kg of an aromatic sulfonate compound of formula

(Y) m —Ar—(Z—S(O) 2 —X) n

wherein each X is independently a substituted or unsubstituted C 1 -C 20 alkyl, substituted or unsubstituted C 1 -C 20 arylalkyl, substituted or unsubstituted C 6 -C 20 aryl, or substituted or unsubstituted C 7 -C 40 alkylaryl,

Z is —O—or substituted or unsubstituted —(—O—C 1-20 —) w —O—, wherein w is 1 to 20,

Ar is a C 6 -C 62 aromatic group; m is 0-3 and n is 3-6; and

each Y is independently C 1 -C 20 alkyl, substituted C 1 -C 20 alkyl, C 6 -C 20 aryl, C 1 -C 8 alkyl- substituted C 6 -C 20 aryl, halogen, nitro, C 1 -C 20 alkoxycarbonyl, C 1 -C 20 alkoxy, or C 1 -C 20 acyl; and

a ionizing radiation stabilizing additive,

wherein the amount of aromatic sulfonate compound is based on the total weight of the polycarbonate and the aromatic sulfonate compound.

17. A method of making a thermoplastic composition comprising melt-blending:

a polycarbonate, and

an aromatic sulfonate compound of formula

(Y) m —Ar—(Z—S(O) 2 —X) n

wherein

each X is independently a substituted or unsubstituted C 1 -C 20 alkyl, substituted or unsubstituted C 1 -C 20 arylalkyl, substituted or unsubstituted C 6 -C 20 aryl, or substituted or unsubstituted C 7 -C 40 alkylaryl,

Z is —O—or substituted or unsubstituted —(—O—C 1-20 —) w —O—, wherein w is 1 to 20,

Ar is a C 6 -C 62 aromatic group; m is 0-3 and n is 3-6; and

each Y is independently C 1 -C 20 alkyl, substituted C 1 -C 20 alkyl, C 6 -C 20 aryl, C 1 -C 8 alkyl- substituted C 6 -C 20 aryl, halogen, nitro, C 1 -C 20 alkoxycarbonyl, C 1 -C 20 alkoxy, or C 1 -C 20 acyl, and

a ionizing radiation stabilizing additive,

wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of the polycarbonate, the aromatic sulfonate compound, and an effective amount of each of a mold-release agent and an antioxidant has, after exposure to a total gamma radiation dose of 83 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 45, when compared to the unexposed molded article.

18. A masterbatch composition comprising:

a polycarbonate, and

5 to 500 mmol/Kg of an aromatic sulfonate compound of formula

(Y) m —Ar—(Z—S(O) 2 —X) n

wherein

each X is independently a substituted or unsubstituted C 1 -C 20 alkyl, substituted or unsubstituted C 1 -C 20 arylalkyl, substituted or unsubstituted C 6 -C 20 aryl, or substituted or unsubstituted C 7 -C 40 alkylaryl,

Z is —O—or substituted or unsubstituted —(—O—C 1-20 —) w —O—, wherein w is 1 to 20,

Ar is a C 6 -C 62 aromatic group; m is 0-3 and n is 3-6; and

each Y is independently C 1 -C 20 alkyl, substituted C 1 -C 20 alkyl, C 6 -C 20 aryl, C 1 -C 8 alkyl- substituted C 6 -C 20 aryl, halogen, nitro, C 1 -C 20 alkoxycarbonyl, C 1 -C 20 alkoxy, or C 1 -C 20 acyl, and

a ionizing radiation stabilizing additive,

wherein the amount of aromatic sulfonate compound is based on the total weight of the polycarbonate and the aromatic sulfonate compound, and wherein a thermoplastic composition comprises the masterbatch composition and a polycarbonate resin.

19. A method of making a thermoplastic composition comprising melt-blending:

a masterbatch composition comprising:

a polycarbonate, and

an aromatic sulfonate compound of formula

(Y) m —Ar—(Z—S(O) 2 —X) n

wherein

each X is independently a substituted or unsubstituted C 1 -C 20 alkyl, substituted or unsubstituted C 1 -C 20 arylalkyl, substituted or unsubstituted C 6 -C 20 aryl, or substituted or unsubstituted C 7 -C 40 alkylaryl,

Z is —O—or substituted or unsubstituted —(—O—C 1-20 —) w —O—, wherein w is 1 to 20,

Ar is a C 6 -C 62 aromatic group; m is 0-3 and n is 3-6; and

each Y is independently C 1 -C 20 alkyl, substituted C 1 -C 20 alkyl, C 6 -C 20 aryl, C 1 -C 8 alkyl- substituted C 6 -C 20 aryl, halogen, nitro, C 1 -C 20 alkoxycarbonyl, C 1 -C 20 alkoxy, or C 1 -C 20 acyl;

a polycarbonate resin; and

a ionizing radiation stabilizing additive,

wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of the polycarbonate, the aromatic sulfonate compound, the polycarbonate resin, and an effective amount of each of a mold-release agent and an antioxidant has, after exposure to a total gamma radiation dose of 83 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 45, when compared to the unexposed molded article.

20. An article comprising the thermoplastic composition of claim 1 .

21. The article of claim 20 , wherein the article has a thickness of 3.2±0.12 millimeters and a transmission of greater than 95% according to ASTM D1003-00, and wherein these properties are maintained after gamma irradiation at a total dose of up to 83 kGy.

22. The thermoplastic composition of claim 1 , wherein each Y is independently fluoro, chloro, bromo, iodo, methoxy carbonyl, ethyl carbonyl, t-butyl carbonyl, cyclohexyl carbonyl, phenyl carbonyl, —OCH 3 , —OCH 2 CH 3 , —O-t-butyl, —O-n-butyl, —O-n-octyl, acetyl, pivaloyl, n-octyloyl, n-dodecoyl, n-stearoyl, benzoyl, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, octadecyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclohexyl, adamantyl, norbornyl, phenyl, C 1 -C 8 alkylphenyl, C 1 -C 8 alkoxyphenyl, or halophenyl.

23. The thermoplastic composition of claim 1 , wherein each Z is independently oxygen diradical, ethanedioxy, 1,2-propanedioxy, 1,3-propanedioxy, 1,2- butanedioxy, 1,3-butanedioxy, 1,4-butanedioxy, 2,3-butanedioxy, 1,2-pentanedioxy, 1,3- pentanedioxy, 1,4-pentanedioxy, 1,5-pentanedioxy, 2,3-pentanedioxy, 2,4-pentanedioxy, 2- methy1-1,2-butanedioxy, 2-methyl-1,3-butanedioxy, 2-methyl-1,4-butanedioxy, 2-methy1-2,3- butanedioxy, 2,2-dimethyl- 1,2-propanedioxy, 2,2-dimethyl-1,3-propanedioxy, 3,3-dimethy1-1,2-propanedioxy, 1,1-dimethyl-2,3-propanedioxy, 1,2-hexanedioxy, 1,3-hexanedioxy, 1,4- hexanedioxy, 1,5-hexanedioxy, 1,6-hexanedioxy, 2,3-hexanedioxy, 2,4-hexanedioxy, 2,5- hexanedioxy, 2-methyl-1,2-pentanedioxy, 2-methyl-1,3-pentanedioxy, 2-methyl-1,4- pentanedioxy, 2-methyl-2,3-pentanedioxy, 2-methyl-2,4-pentanedioxy, 2,2-dimethy1-1,2- butanedioxy, 2,2-dimethyl- 1,3-butanedioxy, 3,3-dimethyl- 1,2-butanedioxy, 1,1-dimethy1-2,3- butanedioxy, octanedioxy, decanedioxy, undecanedioxy, dodecanedioxy, hexadecanedioxy, octadecanedioxy, icosananedioxy, docosananedioxy, cyclopropanedioxy, cyclobutanedioxy, cyclopentanedioxy, cyclohexanedioxy, 1,4-dioxymethyl cyclohexane, ethylenedioxy, 1,2- propylenedioxy, 1,3-propylenedioxy, 1,2-butylenedioxy, 1,4-butylenedioxy, or 1,6-hexylenedioxy.

24. The thermoplastic composition of claim 1 , wherein each X is independently methyl, ethyl, n-propyl, 2-methylpropyl, n-butyl, 2-methylbutyl, 3-methylbutyl, n-pentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, n-hexyl, cyclohexyl, n-octyl, 2- ethylhexyl, n-dodecyl, n-octadecyl n-eicosyl, camphoryl, trifluoromethyl, 2,2,2-trifluoroethyl, perfluoroethyl, perfluoro-n-butyl, perfluoro-n-hexyl, perfluoro-n-octyl, perfluorocyclohexyl, perfluoro-(4-ethylcyclohexyl)-2-ethyl, benzyl, 2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 3,5-dimethylphenyl, 2,3- dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2,3,4- trimethylphenyl, 2,3,5-trimethylphenyl, 3,4,5-trimethylphenyl, 2,4,6-trimethylphenyl, 4- ethylphenyl, 4-n-butylphenyl, 4-tert-butylphenyl, 2-trifluoromethylphenyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-tert-butoxyphenyl, 4-fluorophenyl, 4-chlorophenyl, 4-bromophenyl, naphthyl, C 1 -C 8 alkyl-substituted naphthyl, C 1 -C 8 alkyl ether-substituted naphthyl, or halogen-substituted naphthyl.