Method for controlling haze in an article comprising a polymer composition

1. A method for controlling haze in an article comprising a polytherimide, said method comprising:

(a) providing a polytherimide comprising less than 25 parts per million alkali metal halide; and

(b) fabricating an article from said polytherimide

wherein said polyetherimide comprises repeat units having structure I

 wherein R 1 and R 2 are independently at each occurrence a halogen atom, a nitro group, a cyano group, a C 1 -C 12 aliphatic radical, C 3 -C 12 cycloaliphatic radical, or a C 3 -C 12 aromatic radical; b and c are independently integers from 0 to 3; Q is a C 2 -C 22 aliphatic radical, a C 3 -C 22 cycloaliphatic radical or a C 3 -C 22 aromatic radical; X is a bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, a selenium atom, a hexafluoroisopropylidene group, a carbonyl group or a linking group having structure II

 (c) wherein each G 1 is independently an C 3 -C 20 aromatic radical; E is selected from the group consisting of a C 3 -C 20 cycloaliphatic radical, a C 3 -C 20 aromatic radical, a C 1 -C 20 aliphatic radical, a sulfur-containing linkage, a phosphorus-containing linkage, an ether linkage, a carbonyl group, a tertiary nitrogen atom, and a silicon-containing linkage; R 3 is independently at each occurrence a halogen atom, a C 1 -C 20 aliphatic radical, C 3 -C 20 cycloaliphatic radical, or a C 3 -C 20 aromatic radical; Y 1 is independently at each occurrence a halogen atom, a nitro group, a cyano group, a C 1 -C 20 aliphatic radical, C 3 -C 20 cycloaliphatic radical, or a C 3 -C 20 aromatic radical; each m is independently a number from zero through the number of positions on each respective G 1 available for substitution; p is a whole number from zero through the number of positions on E available for substitution; t is a number greater than or equal to one; s is either zero or one; and u is a whole number including zero, wherein at least one of t, s, and u is not equal to zero.

2. The method according to claim 1 wherein said structural unit Q is derived from a diamine selected from the group consisting of C 2 -C 22 aliphatic diamines, C 3 -C 22 cycloaliphatic diamines, and C 3 -C 22 aromatic diamines.

3. The method according to claim 1 wherein said structure I comprises structural units derived from meta-phenylenediamine, and para-phenylenediamine.

4. The method according to claim 3 wherein said meta-phenylenediamine, and said para-phenylenediamine are present in an amount corresponding to from about 1-99 mole percent and from 99-1 mole percent respectively.

5. The method according to claim 1 wherein said polymer comprising 25 parts per million or less of alkali metal halide is provided by purifying a precursor polymer, said precursor polymer comprising more than about 50 parts per million of alkali metal halide.

6. The method according to claim 5 wherein said precursor polymer comprising more than about 50 parts per million alkali metal halide is prepared by a process which generates alkali metal halide as a by-product.

7. The method according to claim 5 wherein said purifying a precursor polymer comprises subjecting a product mixture comprising (i) a polymer reaction product made by a halo-displacement polymerization process, (ii) a catalyst, (iii) an alkali metal halide, and (iv) a substantially water-immiscible organic solvent, to a series of processing steps, said steps comprising;

(a) quenching the mixture with acid to provide a quenched mixture comprising an organic phase;

(b) perform a solid separation step;

(c) contacting the quenched mixture with water using at least one of a counter-current contact apparatus, an extraction column, a static mixer, a homogenizer, or a mixing vessel;

(d) separating a water-containing phase from the organic phase, using at least one of a liquid/liquid centrifuge, a counter-current contact apparatus, a liquid-liquid extractor, a liquid-liquid continuous extractor, an extraction column, a coalescer, or a settling vessel; and

(e) and isolating the polymer.

8. The method according to claim 7 wherein the polymer comprises the reaction product of a bisphenol A moiety with at least one member selected from the group consisting of 1,3-bis[N-(4-chlorophthalimido)]benzene, 1,4-bis[N-(4-chlorophthalimido)]-benzene, 1,3-bis[N-(3-chlorophthalimido)]benzene, 1,4-bis[N-(3-chlorophthalimido)]benzene, 1-[N-(4-chlorophthalimido)]-3-[N-(3-chlorophthalimido)benzene, 1-[N-(4-chlorophthalimido)]-4-[N-(3-chlorophthalimido)benzene, bis(4-chlorophenyl) sulfone, bis(4-fluorophenyl) sulfone; 1,4-bis(4-chlorobenzoyl)benzene and 1,3-bis(4-chlorobenzoyl)benzene.

9. The method according to claim 1 wherein said alkali metal halide is a alkali metal chloride, alkali metal fluoride or an alkali metal iodide.

10. The method according to claim 9 wherein said alkali metal halide is sodium chloride.

11. The method according to claim 7 wherein the organic solvent is o-dichlorobenzene.

12. The method according to claim 1 , wherein the article exhibits a haze level less than or equal to 10%.

13. The method according to claim 12 , wherein the article exhibits a haze level less than or equal to 5%.

14. A method for controlling haze in an article comprising a polyetherimide composition, said method comprising:

(a) providing a polyetherimide composition comprising less than 25 parts per million alkali metal chloride; and

(b) fabricating an article from said polyetherimide composition;

wherein the polyetherimide comprises repeat units having structure I

 wherein R 1 and R 2 are independently at each occurrence a halogen atom, a nitro group, a cyano group, a C 1 -C 12 aliphatic radical, C 3 -C 12 cycloaliphatic radical, or a C 3 -C 12 aromatic radical; b and c are independently integers from 0 to 3; Q is a C 2 -C 22 aliphatic radical, a C 3 -C 22 cycloaliphatic radical, or a C 3 -C 22 aromatic radical; X is a bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, a selenium atom, a hexafluoroisopropylidene group, a carbonyl group or a linking group having structure II

 wherein each G 1 is independently an C 3 -C 20 aromatic radical; E is selected from the group consisting of a C 3 -C 20 cycloaliphatic radical, a C 3 -C 20 aromatic radical, a C 1 -C 20 aliphatic radical, a sulfur-containing linkage, a phosphorus-containing linkage, an ether linkage, a carbonyl group, a tertiary nitrogen atom, and a silicon-containing linkage; R 3 is independently at each occurrence a halogen atom, a C 1 -C 20 aliphatic radical, C 3 -C 20 cycloaliphatic radical, or a C 3 -C 20 aromatic radical; Y 1 is independently at each occurrence a halogen atom, a nitro group, a cyano group, a C 1 -C 20 aliphatic radical, C 3 -C 20 cycloaliphatic radical, or a C 3 -C 20 aromatic radical; each m is independently a number from zero through the number of positions on each respective G 1 available for substitution; p is a whole number from zero through the number of positions on E available for substitution; t is a number greater than or equal to one; s is either zero or one; and u is a whole number including zero, wherein at one of t, s, and u is not equal to zero.

15. The method of claim 14 , wherein the article exhibits a haze level less than or equal to 10%.

16. The method of claim 15 , wherein the article exhibits a haze level less than or equal to 5%.