阅读说明：本技术 氧化稳定性改进的聚碳酸酯组合物和其制备方法 (Polycarbonate compositions with improved oxidative stability and process for their preparation ) 是由 A·D·博雅斯基 I·维克费尔南德斯 于 2019-12-05 设计创作，主要内容包括：公开了一种在聚合系统中制备聚碳酸酯组合物的方法,所述聚合系统包括单体混合单元、低聚区段和聚合区段。所述方法包括在季鏻催化剂的存在下使二羟基化合物与碳酸二芳基酯化合物熔融聚合,以产生具有含磷副产物的所述聚碳酸酯组合物,所述含磷副产物具有所述季鏻催化剂或所述碳酸二芳基酯化合物中的至少一者。所述方法进一步包括使所述含磷副产物再循环进入所述聚合系统的所述单体混合单元,并且从所述聚合系统中去除所述聚碳酸酯组合物。所述再循环流具有高于或等于40ppm的磷浓度。(A method of preparing a polycarbonate composition in a polymerization system comprising a monomer mixing unit, an oligomerization section, and a polymerization section is disclosed. The method includes melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst to produce the polycarbonate composition having a phosphorus-containing byproduct having at least one of the quaternary phosphonium catalyst or the diaryl carbonate compound. The method further includes recycling the phosphorus-containing byproduct into the monomer mixing unit of the polymerization system and removing the polycarbonate composition from the polymerization system. The recycle stream has a phosphorus concentration greater than or equal to 40 ppm.)

1. A method of making a polycarbonate composition in a polymerization system, wherein the polymerization system comprises a monomer mixing unit, an oligomerization section, and a polymerization section, the method comprising:

melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst to produce a polycarbonate composition comprising a phosphorus-containing byproduct having at least one of the quaternary phosphonium catalyst or the diaryl carbonate compound;

recycling a recycle stream comprising the phosphorus-containing byproduct into the monomer mixing unit of the polymerization system; and is

Removing the polycarbonate composition from the polymerization system;

wherein the recycle stream has a phosphorus concentration higher than or equal to 40, preferably higher than or equal to 50 ppm.

2. The method of claim 1, wherein the phosphorus-containing byproduct comprises a phosphate ester having the formula:

3. a method of making a polycarbonate composition in a polymerization system, the method comprising:

melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst;

recycling phosphorus-containing by-products into the polymerization system; and wherein the recycle stream has a phosphorus-containing byproduct concentration greater than or equal to 280ppm, preferably greater than or equal to 350ppm, such as from 280ppm to 3,500ppm, or from 280 to 1,750 ppm; and is

Wherein the phosphorus-containing byproduct comprises a phosphate ester having the formula:

4. the method of any one or more of the preceding claims, wherein the quaternary phosphonium catalyst comprises tetrabutylphosphonium acetate.

5. The method of any one or more of the preceding claims, wherein the dihydroxy compound is bisphenol a and the diaryl carbonate compound is diphenyl carbonate.

6. The method of any one or more of the preceding claims, wherein the quaternary phosphonium catalyst is present in an amount of 5 to 500 moles of the quaternary phosphonium catalyst per total moles of the dihydroxy compound.

7. The method of any one or more of the preceding claims, wherein the melt polymerizing is further carried out in the presence of an ionic catalyst.

8. The method of any one or more of the preceding claims, wherein the polymerization system further comprises an extraction column that extracts phenol from the oligomerization section and returns at least one of the dihydroxy compound or the diaryl carbonate compound to the oligomerization section.

9. The method of claim 8, wherein the recycle stream comprises phenol, bisphenol A, diphenyl carbonate, tributylphosphine oxide, and phosphate esters.

10. The method of claims 8 and 9, wherein the recovery system further comprises a first extraction column and a second extraction column, and wherein an overhead stream of the second extraction column comprises 80 to 99 wt.% diphenyl carbonate and 200 to 1000ppm tributylphosphine oxide.

11. The method of claim 9, wherein the diphenyl carbonate contains 10 to 100ppm of tributylphosphine oxide in the recovery system.

12. The process of claims 8-11, wherein the extraction of the phosphorus-containing byproduct with the quaternary phosphonium catalyst is a side draw through at least one of the first and second extraction columns.

13. The process of any one or more of the preceding claims, wherein the recycle stream has a phosphorus concentration of 40 to 150ppm, preferably 50 to 100ppm, or 50 to 70 ppm.

14. The process of any one or more of the preceding claims, wherein the recycle stream has a phosphorus concentration of 40 to 500ppm, or 40 to 250ppm, or 50 to 250ppm, preferably 50 to 150ppm, or 50 to 100ppm, and again or 50 to 70 ppm.

15. The method of any one or more of claims 1-13, wherein the recycle stream has a phosphorus concentration greater than or equal to 50 ppm.

16. A polycarbonate prepared by the method of any one or more of the preceding claims.

17. An article comprising the polycarbonate of claim 16.

18. The article of claim 17, wherein the article is a sheet, a film, a multilayer sheet, a multilayer film, a molded part, an extruded profile, a fiber, a coated part, or a foam.

Background

Polycarbonates are useful in the manufacture of articles and components for a wide variety of applications, such as automotive parts, electronics, plastic optical recording media, and optical lenses. Polycarbonates exhibit excellent mechanical properties such as impact resistance, heat resistance, and transparency. However, polycarbonates are susceptible to oxidation and are thus known to be colored over time and the application of heat.

The polycarbonate may be prepared by melt polymerizing a dihydroxy compound and a carbonate compound in the presence of a catalyst. It has been observed that when quaternary organic phosphonium compounds, such as tetrabutylphosphonium acetate (TBPA), are used as catalysts during melt polymerization, the resulting polycarbonates are less unstable to oxidation reactions.

WO 2018/134734 relates to a method of preparing a polycarbonate composition comprising: melt polymerizing a dihydroxy compound with a diaryl carbonate in a polymerization unit, and removing a stream comprising color-inducing species containing isopropenylphenyl-containing groups from the polymerization unit to form a polycarbonate composition, wherein the polycarbonate has a color-inducing species content containing isopropenylphenyl-containing groups of less than 170 parts per million by weight (ppm).

WO 2006/049955 relates to a method of making polycarbonate comprising: melt polymerizing an aromatic dihydroxy compound and a carbonic acid diester in a reactor system in the presence of a polymerization catalyst to produce a byproduct stream, wherein the polymerization catalyst comprises a quaternary phosphonium compound; and purifying the byproduct stream to separate the carbonic acid diester, wherein the separated carbonic acid diester has a phosphorus concentration of less than or equal to 30 ppm.

Accordingly, there remains a need for polycarbonate compositions and methods of making the same that provide improved oxidative stability while not affecting other useful qualities of the polycarbonate compositions.

Disclosure of Invention

Disclosed herein are polycarbonate compositions having improved oxidative stability and methods for making the same.

A method of preparing a polycarbonate composition in a polymerization system is disclosed. The polymerization system includes a monomer mixing unit, an oligomerization zone, and a polymerization zone. The method includes melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst to produce a polycarbonate composition having a phosphorus-containing byproduct having at least one of the quaternary phosphonium catalyst or the diaryl carbonate compound. The method further includes recycling the phosphorus-containing byproduct into a monomer mixing unit of the polymerization system and removing the polycarbonate composition from the polymerization system. The recycle stream has a phosphorus concentration greater than or equal to 40 parts per million (ppm), or greater than or equal to 50ppm, such as from 40 to 500ppm, preferably from 50 to 250ppm, or from 50 to 150 ppm.

A method of preparing a polycarbonate composition in a polymerization system can comprise: melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst; recycling the phosphorus containing by-product to the polymerization system; and wherein the recycle stream has a phosphorus-containing byproduct concentration greater than or equal to 280ppm, preferably greater than or equal to 350ppm, such as from 280ppm to 3,500ppm, or from 280 to 1,750 ppm; and wherein the phosphorus-containing byproduct comprises a phosphate ester having the formula:

also disclosed herein is a polycarbonate composition prepared by the above method.

The above described and other features are exemplified by the following figures, detailed description, embodiments, and claims.

Brief Description of Drawings

Referring now to the drawings, which are exemplary embodiments and wherein like elements are numbered alike.

FIG. 1 is a schematic representation of an aggregation system according to example 1;

FIG. 2 is a schematic representation of a polymerization system according to example 2, wherein the second scrubber bottoms are not recycled into the system;

FIG. 3 is a schematic representation of an aggregation system according to example 3;

FIG. 4 is a schematic representation of an aggregation system according to example 4;

FIG. 5 is a schematic representation of an aggregation system according to example 5;

FIG. 6 shows the cookie (cookie) trial values during TBPA loading on a commercial scale;

figure 7 is a graphical representation of the effect of TBPO loading on the patty test values of a; and is

Figure 8 is a graphical representation of the effect of TBPO loading on the patty test values of b.

Detailed Description

Embodiments of the present invention relate to a method of making a polycarbonate composition in a polymerization system. The polymerization system includes a monomer mixing unit, an oligomerization zone, and a polymerization zone. The method includes melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst to produce a polycarbonate composition having a phosphorus-containing byproduct having at least one of the quaternary phosphonium catalyst or the diaryl carbonate compound. The method further includes recycling the phosphorus-containing byproduct into a monomer mixing unit of the polymerization system and removing the polycarbonate composition from the polymerization system. The polycarbonate composition exiting the polymerization system has a phosphorus concentration of 2 to 10 ppm.

The melt polycarbonate process is based on the reaction of a dihydroxy compound and a carbonate precursor in a melt stage. As further described herein, the reaction may occur in a series of reactors, where the combined effects of catalyst, temperature, vacuum, and agitation allow the monomers to react and remove reaction byproducts to shift the reaction equilibrium and grow the polymer chains. Common polycarbonates made by melt polymerization are those derived from bisphenol a (bpa) via reaction with diphenyl carbonate (DPC). The reaction may be catalysed by a quaternary catalyst, such as a quaternary phosphonium catalyst, for example tetrabutylphosphonium acetate (TBPA).

More specifically, the methods disclosed herein comprise melt polymerizing a dihydroxy compound having formula (I) with a diaryl carbonate compound having formula (a) in a polymerization system:

wherein R is^aAnd R^bEach independently is halogen, C_1-12Alkoxy or C_1-12An alkyl group; p and q are each independently an integer from 0 to 4; x^aIs substituted or unsubstituted C_3-18A cycloalkylene radical of the formula-C (R)^c)(R^d) C of (A-C)_1-25Alkylene group, wherein R^cAnd R^dEach independently is hydrogen, C_1-12Alkyl radical, C_1-12Cycloalkyl radical, C_7-12Aralkyl radical, C_1-12Heteroalkyl or cyclic C_7-12Heteroaralkyl, or of the formula-C (═ R)^e) A group of (a) wherein R^eIs divalent C_1-12A hydrocarbyl group;

wherein each n is independently an integer from 1 to 3; and each RⁱIndependently is a straight or branched chain, optionally substituted C_1-34Alkyl radical, C_1-34Alkoxy radical, C_5-34Cycloalkyl radical, C_7-34Alkylaryl group, C_6-34Aryl, a halogen group OR-C (═ O) OR ', wherein R' is H, straight OR branched C_1-34Alkyl radical, C_1-34Alkoxy radical, C_5-34Cycloalkyl radical, C_7-34Alkylaryl or C_6-34And (4) an aryl group.

The polymerization process may be carried out in the presence of TBPA.

It has been observed that when TBPA is used in a polycarbonate production process, tributylphosphine oxide (TBPO) and other phosphate esters are produced in the process. For example, in addition to TBPO, the following nonionic compounds having formula (II) were identified:

thus, the use of TBPA in polycarbonate production results in the production of TBPO and phosphate esters, thereby providing higher phosphorus (P) concentrations, and the resulting polycarbonate product is less unstable to oxidation reactions. TBPO is a volatile and can vaporize under the conditions of the polymerization reaction, thereby assisting its separation during the polymerization process. In this process, because TBPO has a similar vapor pressure to DPC, a large amount of TBPO can be distilled off together with DPC. Thus, it has been determined that TBPO and related phosphate esters produced by the polymerization reaction can be recycled into the process via a recycle loop along with the recovered DPC. It has surprisingly been further observed that an increased amount of TBPA results in a higher content of TBPO and related phosphates being produced.

It is desirable that the recycle stream (e.g., phosphorus-containing by-products entering the monomer mixing unit of the polymerization system, such as recycled DPC) have a phosphorus content of greater than or equal to 40ppm, or greater than or equal to 50ppm, such as 40 to 500ppm, or 40 to 250ppm, or 50 to 250ppm, preferably 50 to 150ppm, or 50 to 100ppm, and again 50 to 70 ppm.

The oxidative stability of the polycarbonates prepared by the process described herein was determined using the "patty test". The test consists of heating 50g of polycarbonate pellets in air at a temperature of 250 ℃ for 2 hours. The resulting plate (plain) of the "patty test" was used for color measurement.

It has also been observed that undesirable color-inducer species are recycled into the process via a recycle loop along with DPC, TBPO and phosphate esters, and polycarbonate with undesirable levels of color-inducer species is produced. The initial color of the polycarbonate and the color after aging are influenced by the amount of the color-inducing species present. For example, the color inducer can be an isopropenyl-containing compound or 9, 9-Dimethylxanthone (DMX). Thus, lower levels of color-inducing species are associated with lower coloration in the polycarbonate and are therefore desirable. Color values (brightness (L), red/magenta and green (a), yellow/blue (b) and Yellowness Index (YI)) were calculated from the absorption spectra of the plates (patties) between 360 nanometers (nm) and 750 nm. The spectra were measured in transmission mode on a Macbeth7000A setup and included UV. Values for L, a, b and YI have been calculated according to ASTM D1925. The present inventors have discovered that operational variations of the polymerization process as described herein allow for the production of polycarbonates having lower color inducer species concentrations and increased desired levels of TBPO and related phosphate esters produced (i.e., P levels).

The polycarbonate compositions prepared by the methods described herein can include greater than or equal to 1ppm, or greater than or equal to 7ppm, or greater than or equal to 14ppm, preferably greater than or equal to 28ppm (e.g., 1 to 30ppm) of tributyl TBPO and other phosphate esters, such as compounds having formula (II):

TBPO (weight average molecular weight (Mw): 218.32g/mol) and TBPA (Mw: 318.47g/mol) contents were determined based on the phosphorus content associated with those species. In other words, the measured 1ppm of elemental P represents 7.0ppm TBPO or 10.3ppm TBPA.

"polycarbonate" as used herein means a polymer or copolymer having repeating structural carbonate units of formula (1):

wherein R is¹At least 60% of the total number of radicals being aromatic, or each R¹Containing at least one C_6-30And (4) an aryl group. Specifically, each R¹May be derived from an aromatic dihydroxy compound such as formula (2) or a dihydroxy compound such as a bisphenol of formula (3).

In the formula (2), each R^hIndependently of one another, a halogen atom such as bromine, C_1-10Hydrocarbyl radicals, such as C_1-10Alkyl, halogen substituted C_1-10Alkyl radical, C_6-10Aryl or halogen substituted C_6-10An aryl group; and n is 0 to 4.

In the formula (3), R^aAnd R^bEach independently is halogen, C_1-12Alkoxy or C_1-12An alkyl group; and p and q are each independently integers of 0 to 4, such that when p or q is less than 4, the valency of each carbon of the ring is filled with hydrogen. In one aspect, p and q are each 0, or p and q are each 1, and R^aAnd R^bEach is C_1-3The alkyl group, specifically methyl, is meta to the hydroxyl group on each arylene group. X^aA bridging group to link the two hydroxy-substituted aryl groups, wherein the bridging group and each C₆Hydroxy substituents of arylene radicals at C₆Ortho, meta or para (specifically para) to each other on the arylene group, e.g. a single bond, -O-, -S-, -S (O) -, -S (O)₂-, -C (O) -or C_1-18An organic group, which may be cyclic or acyclic, aromatic or non-aromatic and may also contain heteroatoms such as halogens, oxygen, nitrogen, sulfur, silicon or phosphorus. For example, X^aC which may be substituted or unsubstituted_3-18A cycloalkylene group; having the formula-C (R)^c)(R^d) C of (A-C)_1-25Alkylene group, wherein R^cAnd R^dEach independently is hydrogen, C_1-12Alkyl radical, C_1-12Cycloalkyl radical, C_7-12Aralkyl radical, C_1-12Heteroalkyl or cyclic C_7-12A heteroaralkyl group; or has the formula-C (═ R)^e) A group of (a) wherein R^eIs divalent C_1-12A hydrocarbyl group.

Examples of the bisphenol compound include 4,4' -dihydroxybiphenyl, 1, 6-dihydroxynaphthalene, 2, 6-dihydroxynaphthalene, bis (4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) -1-naphthylmethane, 1, 2-bis (4-hydroxyphenyl) ethane, 1, 1-bis (4-hydroxyphenyl) -1-phenylethane, 2- (4-hydroxyphenyl) -2- (3-hydroxyphenyl) propane, bis (4-hydroxyphenyl) phenylmethane, 2, 2-bis (4-hydroxy-3-bromophenyl) propane, 1, 1-bis (hydroxyphenyl) cyclopentane, 1, 1-bis (4-hydroxyphenyl) cyclohexane, 1, 1-bis (4-hydroxyphenyl) isobutylene, 1, 1-bis (4-hydroxyphenyl) cyclododecane, trans-2, 3-bis (4-hydroxyphenyl) -2-butene, 2, 2-bis (4-hydroxyphenyl) adamantane, α, α' -bis (4-hydroxyphenyl) toluene, bis (4-hydroxyphenyl) acetonitrile, 2, 2-bis (3-methyl-4-hydroxyphenyl) propane, 2, 2-bis (3-ethyl-4-hydroxyphenyl) propane, 2, 2-bis (3-n-propyl-4-hydroxyphenyl) propane, 2, 2-bis (3-isopropyl-4-hydroxyphenyl) propane, 2, 2-bis (3-sec-butyl-4-hydroxyphenyl) propane, 2, 2-bis (3-tert-butyl-4-hydroxyphenyl) propane, 2, 2-bis (3-cyclohexyl-4-hydroxyphenyl) propane, 2, 2-bis (3-allyl-4-hydroxyphenyl) propane, 2, 2-bis (3-methoxy-4-hydroxyphenyl) propane, 2, 2-bis (4-hydroxyphenyl) hexafluoropropane, 1, 1-dichloro-2, 2-bis (4-hydroxyphenyl) ethylene, 1, 1-dibromo-2, 2-bis (4-hydroxyphenyl) ethylene, 1, 1-dichloro-2, 2-bis (5-phenoxy-4-hydroxyphenyl) ethylene, 4,4' -dihydroxybenzophenone, 3, 3-bis (4-hydroxyphenyl) -2-butanone, 1, 6-bis (4-hydroxyphenyl) -1, 6-hexanedione, ethylene glycol bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) sulfone, 9, 9-bis (4-hydroxyphenyl) fluorene, 2, 7-dihydroxypyrene, 6,6' -dihydroxy-3, 3,3',3' -tetramethylspiro (bis) indane ("spirobiindane bisphenol"), 3, 3-bis (4-hydroxyphenyl) phthalimide, 2, 6-dihydroxydibenzo-p-dioxin, 2, 6-dihydroxythianthrene, 2, 7-dihydroxyphenoxathiin, 2, 7-dihydroxy-9, 10-dimethylphenazine, 3, 6-dihydroxydibenzofuran, 3, 6-dihydroxydibenzothiophene, and 2, 7-dihydroxycarbazole; resorcinol, substituted resorcinol compounds such as 5-methyl resorcinol, 5-ethyl resorcinol, 5-propyl resorcinol, 5-butyl resorcinol, 5-tert-butyl resorcinol, 5-phenyl resorcinol, 5-cumyl resorcinol, 2,4,5, 6-tetrafluoro resorcinol, 2,4,5, 6-tetrabromo resorcinol, or the like; catechol, hydroquinone, substituted hydroquinones such as 2-methyl hydroquinone, 2-ethyl hydroquinone, 2-propyl hydroquinone, 2-butyl hydroquinone, 2-t-butyl hydroquinone, 2-phenyl hydroquinone, 2-cumyl hydroquinone, 2,3,5, 6-tetramethyl hydroquinone, 2,3,5, 6-tetra-t-butyl hydroquinone, 2,3,5, 6-tetrafluorohydroquinone, 2,3,5, 6-tetrabromo hydroquinone, or the like.

Specific dihydroxy compounds include resorcinol, 2, 2-bis (4-hydroxyphenyl) propane ("bisphenol a" or "BPA"), 3, 3-bis (4-hydroxyphenyl) phthalimidine, 2-phenyl-3, 3' -bis (4-hydroxyphenyl) phthalimidine (also known as N-phenylphenolphthalein bisphenol, "PPPBP", or 3, 3-bis (4-hydroxyphenyl) -2-phenylisoindolin-1-one), 1, 1-bis (4-hydroxy-3-methylphenyl) cyclohexane, and 1, 1-bis (4-hydroxyphenyl) -3,3, 5-trimethylcyclohexane (isophorone bisphenol).

The polycarbonate can have an intrinsic viscosity of 0.3 to 1.5 deciliters per gram (dl/gm), specifically 0.45 to 1.0dl/gm, as measured in chloroform at 25 ℃. The polycarbonate can have a weight average molecular weight of 10,000 to 200,000 daltons, specifically 20,000 to 100,000 daltons, as measured by Gel Permeation Chromatography (GPC), using a crosslinked styrene-divinylbenzene column and calibrated to a bisphenol a homopolycarbonate reference. GPC samples were prepared at a concentration of 1 mg/ml and eluted at a flow rate of 1.5 ml/min. Polycarbonates have flow properties that can be used to make thin articles. Melt volume flow rate (often abbreviated MVR) measures the rate of extrusion of a thermoplastic through an orifice at a specified temperature and load. Polycarbonates that can be used to form thin articles can have an MVR of 50 to 1 cubic centimeter per 10 minutes (cc/10min), specifically 30 to 3cc/10min, measured at 300 ℃/1.2 kg. Combinations of polycarbonates having different flow properties can be used to achieve the desired overall flow properties.

"polycarbonate" includes homopolycarbonates (wherein each R in the polymer is¹Same) containing different R in the carbonate¹Copolymers of structural moieties ("copolycarbonates"), and copolymers comprising carbonate units and other types of polymer units, such as ester units or siloxane units. The polycarbonate may be a homopolycarbonate. Optionally, the polycarbonate may be a copolymer.

In the melt polymerization process, the polycarbonate may be prepared by reacting a dihydroxy compound and a carbonate precursor in the presence of a catalyst in a molten state. The reaction may be carried out in typical polymerization equipment such as continuous stirred reactors (CSTRs), plug flow reactors, wire wetting fall polymerizers, free fall polymerizers, horizontal polymerizers, wiped film polymerizers, BANBURY mixers (BANBURY mixers), single or twin screw extruders, or combinations comprising one or more of the foregoing. Volatile monohydric phenol is removed from the molten reactants by distillation and the polymer is isolated as a molten residue. The melt polymerization may be carried out as a batch process. Optionally, the melt polymerization can be carried out as a continuous process. It is noted that melt polymerization can be carried out in different sections of the polymerization apparatus as a combination of batch and continuous processes. In each case, the melt polymerization conditions used may comprise two or more different reaction stages.

For example, the polymerization may include: an oligomerization stage in which the starting dihydroxy compound and a carbonate precursor such as a diaryl carbonate are converted to an oligomeric polycarbonate; and a second reaction stage, also referred to as polymerization stage, in which the oligomeric polycarbonate formed in the oligomerization stage is converted to high molecular weight polycarbonate. The oligomerization stage can comprise 1 or more, or 2 to 4 oligomerization units (e.g., 2 to 4 continuous stirred tanks). When there are 2 or more oligomerization units in series, one or both of the temperature increase and pressure decrease can occur from one unit to the next. The polymerization stage may comprise 1 or more, or 2 polymerization units (e.g. 2 horizontal or wire wet-fall polymerizers). The polymerization stage can include one or more polymerization units that can polymerize the polycarbonate to a number average molecular weight (Mn) of, for example, 20,000 to 50,000 daltons using polycarbonate standards. After polycarbonate formation, the polycarbonate composition can then be optionally quenched and devolatilized (devolatilized) in a devolatilization unit, where the Mn of the polycarbonate does not increase significantly (e.g., Mn does not increase by more than 10 weight percent (% by weight)) and temperature, pressure, and residence time are used to reduce the concentration of low Mn components, such as components having an Mn of less than 1,000 daltons. An oligomeric unit is defined herein as an oligomeric unit that produces polycarbonate oligomers having an Mn of less than or equal to 8,000 daltons, and a polymeric unit is defined herein as a polymeric unit that produces polycarbonates having a number average molecular weight (Mn) of greater than 8,000 daltons. It is noted that although less than or equal to 8,000 daltons is used herein to define the molecular weight achieved in the oligomerization stage, it is readily understood by those skilled in the art that the molecular weight is used to define the oligomerization stage, wherein the oligomer molecular weight can be greater than 8,000 daltons. "staged" polymerization conditions can be used in a continuous polymerization system wherein starting monomers are oligomerized in a first reaction unit and the oligomeric polycarbonate formed in that unit is continuously transferred to one or more downstream reactors in which the oligomeric polycarbonate is converted to high molecular weight polycarbonate. Typically, the oligomeric polycarbonate produced in the oligomerization stage has a number average molecular weight of 1,000 to 7,500 daltons. In one or more subsequent polymerization stages, the number average molecular weight of the polycarbonate can be increased to, for example, 8,000 and 25,000 daltons (using polycarbonate standards), or 13,000 to 18,000 daltons.

Typically, no solvent is used in the process, and the reactants dihydroxy compound and carbonate precursor are in a molten state. The reaction temperature may be 100 to 350 degrees Celsius (. degree. C.), or 180 to 310 ℃. The pressure may be atmospheric, superatmospheric, or a pressure in the range of atmospheric to 15 torr in the initial stages of the reaction and reduced pressure in subsequent stages, for example, in the range of 0.2 to 15 torr. Likewise, polymerization may occur in a series of polymerization units, each of which may individually have an elevated temperature and/or vacuum. For example, the oligomerization stage can occur at a temperature of 100 to 280 ℃, or 140 to 240 ℃, and the polymerization stage can occur at a temperature of 240 to 350 ℃, or 280 to 300 ℃, or 240 to 270 ℃, or 250 to 310 ℃, wherein the temperature in the polymerization stage is higher than the temperature in the oligomerization stage. The reaction time from the initial oligomerization unit to the final polymerization unit is generally 0.1 to 15 hours (hr). As used herein, the final polymerized unit refers to the final polymerized unit in the melt polymerization where the last increase in molecular weight occurs. For example, the quencher can be added to the polycarbonate resin after the final polymerization unit (e.g., after a point at which the weight average molecular weight (Mw) of the polycarbonate resin based on polystyrene standards will increase by less than or equal to 10%) and optionally prior to any melt filtration.

Likewise, oligomerization can occur at a pressure greater than or equal to 10 kilopascals absolute (kpa (a)); or the oligomerization can comprise at least two oligomerization units, wherein a first oligomerization unit can have a pressure greater than or equal to 10kpa (a) and a second oligomerization unit can have a pressure from 1.5 to 9kpa (a), wherein the first oligomerization unit is upstream of the second oligomerization unit, wherein one or more oligomerization units can be located before, during, or after the polymerization unit.

The polymerisation stage following the oligomerisation stage may comprise polymerisation in one or two polymerisation units. The first polymerization unit can be at a temperature of 240 to 350 ℃, or 260 to 310 ℃, and a pressure of 0.1 to 1kpa (a). The second polymerization unit can be at a temperature of 240 to 350 ℃, or 260 to 300 ℃, and a pressure less than or equal to 0.5kpa (a). The polycarbonate may be devolatilized after the final polymerization. Final polymerization, as used herein, refers to polymerization in which the final increase in molecular weight occurs. For example, the Mw of the polycarbonate increases by less than or equal to 10% after the final polymerization.

After the final polymerization unit, the polymer may be introduced to a reactor, extruded, subjected to filtration in a melt filter, or a combination comprising one or more of the foregoing. It is noted that the melt filter may be located before or after the extruder. For example, a melt polymerization process for preparing a polycarbonate composition can comprise: melt polymerizing a dihydroxy compound and a carbonate precursor to produce a molten reaction product; quenching the molten reaction product; filtering the molten reaction product in a melt filter upstream of any extruder; optionally, introducing an additive to form a mixture; and extruding the mixture to form a polycarbonate composition. Likewise, a melt polymerization process for preparing a polycarbonate composition can comprise: melt polymerizing a polycarbonate; introducing a quencher composition and optional additives to form a mixture; and extruding the mixture to form a polycarbonate composition.

The polycarbonate can be, for example, a bisphenol a polycarbonate having a Mw of 21,800 daltons based on polystyrene standards, having a melt flow (ASTM D1238-04, 300 ℃, 2.16 kilograms (kg)) of 24 to 32 grams per 10 minutes (g/10 min).

The polycarbonate can have a melt flow of 4 to 40 g/10min, e.g., 4.5 to 15 g/10min or 15 to 35 g/10min, as determined by ASTM D1238-04 at 300 ℃, 1.5 kg. The polycarbonate can have a melt flow of 5 to 15 g/10min as determined by ASTM D1238-04 at 250 ℃ under 1.5 kg.

Catalysts used in the melt transesterification polymerization production of polycarbonates may include alpha catalysts and beta catalysts. Alpha catalysts may contain a source of basic or alkaline earth ions (a source of alkali or alkaline earth ions) and are generally more thermally stable and less volatile than beta catalysts.

The ionic catalyst comprises a compound having the formula (4)

Wherein i + ii + iii + iv is greater than or equal to 16, or from 16 to 50, or from 20 to 35; and wherein i is greater than or equal to ii +2, or greater than or equal to ii +5, or greater than or equal to ii +8, or greater than or equal to ii +2 and less than or equal to ii + 20. In formula 4, i may be 8 to 20, or 8 to 12. In formula 4, ii may be 6 to 10. In formula 4, ii, iii and iv may be the same or different; or ii and iii may be the same and i and iv may be the same. In formula I, I may equal iv and ii may equal iii. In formula 4, iii and iv may be equal to i.

Anion A^-Can comprise, for example, a halide (such as chlorine or bromine), a hydroxide, an alkyl, an aryl, a dialkyl, a phosphate (such as a fluorophosphate), a phosphinate (such as an alkylphosphonite), an alkyltoluene sulfonate, a cyanamide, an alkylsulfate, an amide group, a carboxylate, a sulfate, a borate, an alkyl ester, or a combination comprising at least one of the foregoing. The anion can include tetrafluoroborate, dicyanamide, bis (trifluoromethanesulfonyl) amide, tosylate, carboxylate, phosphonite, dialkylphosphate, alkylsulfate, hexafluorophosphate, bis (2,4, 4-trimethylpentyl) phosphinate, acetate, hydroxide, benzoate, formate, propionate, butyrate, phenolate, trifluoromethanesulfonimide, phenoxide, or a combination comprising at least one of the foregoing. The ionic catalyst may be encapsulatedA tributylhexadecylphosphonium catalyst, a trihexylphosphonium catalyst, a trihexyltetradecylphosphonium catalyst, a tetraoctylphosphonium catalyst, a tetradecyltrihexylphosphonium catalyst, or a combination comprising at least one of the foregoing. The ionic catalyst can comprise trihexyltetradecylphosphonium, such as trihexyltetradecylphosphonium Tetradecanoate (TDPD), trihexyltetradecylphosphonium 2,4, 4-Trimethylpentylphosphinate (TDPP), or a combination comprising at least one of the foregoing.

The amount of ionic catalyst can be added based on the total number of moles of dihydroxy compound employed in the polymerization reaction. When referring to the ratio of ionic catalyst to all dihydroxy compounds employed in the polymerization reaction, it is convenient to refer to the number of moles of ionic catalyst per mole of dihydroxy compound or compounds, meaning the number of moles of ionic catalyst divided by the sum of the number of moles of each individual dihydroxy compound present in the reaction mixture. The amount of ionic catalyst may be employed in an amount of 1 to 80, or 2 to 50, or 3 to 12, or 5 to 9 micromoles per total mole of dihydroxy compound.

The ionic catalyst may be an ionic liquid, e.g. comprising ions in liquid form. In some cases, the ionic liquid will not decompose or vaporize upon melting.

The beta catalyst may comprise a quaternary catalyst. The quaternary catalyst comprises a quaternary ammonium compound, a quaternary phosphonium compound, or a combination comprising at least one of the foregoing. The quaternary ammonium compound can be of the structure (R)⁴)₄N⁺A compound of X-, wherein each R⁴Are identical or different and are C_1-20Alkyl radical, C_4-20Cycloalkyl or C_4-20An aryl group; and X-is an organic or inorganic anion, such as hydroxide, halide, carboxylate, sulfonate, sulfate, formate, carbonate or bicarbonate. Examples of organic quaternary ammonium compounds include tetramethylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium acetate, tetramethylammonium formate, tetrabutylammonium acetate, and combinations comprising at least one of the foregoing.

The quaternary phosphonium compound can be of the structure (R)⁵)₄P⁺A compound of X-, wherein each R⁵Are the same or different, andis C_1-20Alkyl radical, C_4-20Cycloalkyl or C_4-20An aryl group; and X "is an organic or inorganic anion, for example hydroxide, phenoxide, halide, carboxylate such as acetate or formate, sulfonate, sulfate, formate, carbonate or bicarbonate. In the case where X-is a polyvalent anion such as carbonate or sulfate, it is understood that the positive and negative charges in the quaternary ammonium and quaternary phosphonium structures are properly balanced. For example, at R²⁰To R²³Each is methyl and X^-In the case of carbonate, X is understood to be^-Represents 2 (CO)₃ ^-2)。

Examples of organic quaternary phosphonium compounds include tetramethyl phosphonium hydroxide, tetramethyl phosphonium acetate, tetramethyl phosphonium formate, tetrabutyl phosphonium hydroxide, tetraethyl phosphonium acetate, tetrapropyl phosphonium acetate, TBPA, tetrapentyl phosphonium acetate, tetrahexyl phosphonium acetate, tetraheptyl phosphonium acetate, tetraoctyl phosphonium acetate, tetradecyl phosphonium acetate, tetradodecyl phosphonium acetate, tetramethylphenyl phosphonium acetate, tetramethylphosphonium benzoate, tetraethyl phosphonium benzoate, tetrapropyl phosphonium benzoate, tetraphenyl phosphonium benzoate, tetraethyl phosphonium formate, tetrapropyl phosphonium formate, tetraphenyl phosphonium formate, tetramethylphosphonium propionate, tetraethyl phosphonium propionate, tetrapropyl phosphonium propionate, tetramethyl phosphonium butyrate, tetraethyl phosphonium butyrate, and tetrapropyl phosphonium butyrate, tetraphenyl phosphonium acetate (TPPA), tetraphenyl phosphonium phenolate (TPPP), and combinations comprising at least one of the foregoing. The quaternary catalyst can comprise tetrabutylphosphonium acetate, TPPP, TPPA, or a combination comprising at least one of the foregoing. In an embodiment of the invention, the beta catalyst is TBPA.

The amount of the optional quaternary catalyst can be added based on the total number of moles of dihydroxy compound employed in the polymerization reaction. When referring to the ratio of catalyst, e.g., phosphonium salt, to all dihydroxy compounds employed in the polymerization reaction, it is convenient to refer to the moles of phosphonium salt per mole of dihydroxy compound or compounds, meaning the moles of phosphonium salt divided by the sum of the moles of each individual dihydroxy compound present in the reaction mixture. The amount of the optional quaternary catalyst (e.g., organoammonium or phosphonium salt) can each independently be 1X 10 per total mole of dihydroxy compound in the monomer mixture^-2To 1X 10^-5Or 1X 10^-3To 1X 10^-4Molar amounts are used.

The catalyst may comprise a basic catalyst (alkali catalyst) which is generally more thermally stable than the quaternary catalyst and may therefore be used throughout the transesterification including during and after oligomerization, for example in the polymerization unit, during polymerization. The basic catalyst may be added to the polymerization at any stage in the polymerization, for example upstream of the monomer mix unit, and/or directly to the monomer mix unit, and/or after the monomer mix unit; and/or upstream of the polymerization unit, and/or directly into the polymerization unit, and/or after the polymerization unit (e.g., into the first stage polymerization unit and/or the second reaction stage polymerization unit). Likewise, the catalyst addition process may be free of a basic catalyst addition step.

The melt polymerization can be carried out in the absence of a basic catalyst. The melt polymerization may be free of a basic catalyst addition step. When a basic catalyst is added, the basic catalyst may be added to the oligomerization unit. When a basic catalyst is added, the basic catalyst may be added to the polymerization unit.

Capping agents (also referred to as chain stoppers or chain terminators) may be included during polymerization to provide end groups. The end-capping agent (and thus the end groups) is selected based on the desired properties of the polycarbonate. Illustrative of exemplary capping agents are: monocyclic phenols, e.g. phenol and C₁-C₂₂Alkyl-substituted phenols, such as p-cumylphenol, resorcinol monobenzoate, and p-and tert-butylphenol, monoethers of diphenols, such as p-methoxyphenol, and alkyl-substituted phenols with a branched alkyl substituent having from 8 to 9 carbon atoms, 4-substituted 2-hydroxybenzophenones and their derivatives, aryl salicylates, monoesters of diphenols, such as resorcinol monobenzoate, 2- (2-hydroxyaryl) -benzotriazoles and their derivatives, 2- (2-hydroxyaryl) -1,3, 5-triazines and their derivatives, chlorinated monocarboxylic acids, such as benzoyl chloride, C₁-C₂₂Alkyl-substituted benzoyl chlorides, toluoyl chloride, bromobenzoyl chloride, cinnamoyl chloride, and 4-methanotetrahydrophthalimidobenzoyl chloride (4-nadimidenzoyl chloride), polycyclic monocarboxylic acid chlorides such as trimellitic anhydride chloride, and naphthoyl chloride, functionalized chlorides of aliphatic monocarboxylic acids such as acryloyl chloride and methacryloyl chloride, and monochloroformates such as phenyl chloroformate, alkyl-substituted phenyl chloroformate, p-cumyl phenyl chloroformate, and toluene chloroformate. Combinations of different end groups may be used.

The polymerization process may include zones of parallel polymerization, where parallel polymerization refers to the division of a polycarbonate stream into two or more streams that may or may not later undergo the same polymerization conditions (i.e., they may reach different molecular weights, have different additives added, etc.). For example, polycarbonate can be prepared in the first part of the polymerization process, and the stream comprising polycarbonate can be split into two or more streams and directed to 2 or more parallel operating lines.

The quencher composition can be added at one or more locations in the melt preparation of the present polycarbonates, for example as described in example 1 and shown in fig. 1, to reduce the activity of the ionic catalyst or optional basic catalyst. The quencher composition comprises a quencher (also referred to herein as a quencher). Conversely, melt polymerization can occur in the absence of a basic catalyst and thus can be free of a quencher. One of the possible quencher species is butyl tosylate (CAS 778-28-9).

The quencher may comprise a sulfonate ester, such as of the formula R₁SO₃R₂Alkyl sulfonate of (2), wherein R₁Is hydrogen, C₁-C₁₂Alkyl radical, C₆-C₁₈Aryl or C₇-C₁₉Alkylaryl, and R₂Is C₁-C₁₂Alkyl radical, C₆-C₁₈Aryl or C₇-C₁₉An alkaryl group. Examples of the alkyl sulfonate include benzenesulfonate, p-toluenesulfonate, ethylbenzene sulfonate, n-butyl benzenesulfonate, octyl benzenesulfonate and phenyl benzenesulfonate, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, n-butyl p-toluenesulfonate, octyl p-toluenesulfonate and phenyl p-toluenesulfonate. The sulfonate ester may comprise an alkyl tosylate, such asN-butyl tosylate. The sulfonate ester can be present in the quencher composition in an amount of 0.1 to 10 volume percent (vol%), or 0.1 to 5 vol%, or 0.5 to 2 vol%, based on the total volume of the quencher composition.

The quencher may comprise a boronic ester (e.g., B (OCH)₃)₃，B(OCH₂CH₃)₃And B (OC)₆H₆)₃) Zinc borate, boron phosphate, aluminium stearate, aluminium silicate, zirconium carbonate, C₁-C₁₂Zirconium alkoxide, zirconium hydroxy carboxylate, gallium phosphide, gallium antimonide, germanium oxide, C₁-C₃₂Organic germanium compound, C₄-C₃₂Tetraorganotin compound, C₆-C₃₂Hexaorganotin compounds (e.g., [ (C)₆H₆O)Sn(CH₂CH₂CH₂CH₃)₂]₂O)，Sb₂O₃Antimony oxide, C₁-C₃₂Antimony alkyl, bismuth oxide, C₁-C₁₂Alkyl bismuth, zinc acetate, zinc stearate, C₁-C₃₂Titanium alkoxides, and titanium oxide, phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, polyphosphoric acid, boric acid, hydrochloric acid, hydrobromic acid, sulfuric acid, sulfurous acid, adipic acid, azelaic acid, dodecanoic acid, L-ascorbic acid, aspartic acid, benzoic acid, formic acid, acetic acid, citric acid, glutamic acid, salicylic acid, nicotinic acid, fumaric acid, maleic acid, oxalic acid, benzenesulfinic acid, C₁-C₁₂Dialkyl sulfates (e.g., dimethyl sulfate and dibutyl sulfate); having the formula (R)^aSO₃ ^-)(PR^b ₄)⁺Wherein R is^aIs hydrogen, C₁-C₁₂Alkyl radical, C₆-C₁₈Aryl or C₇-C₁₉Alkylaryl and each R^bIndependently of one another is hydrogen, C₁-C₁₂Alkyl or C₆-C₁₈An aryl group; having the formula A¹-(Y¹-SO₃X¹)_mWherein A is¹Is C having a valence m₁-C₄₀Hydrocarbyl radical, Y¹Is a single bond or an oxygen atom, X¹Is of the formula-CR¹⁵R¹⁶R¹⁷One equivalent of a metal cation, an ammonium cation (e.g. NR)^b ₃ ⁺Wherein each R^bIndependently of one another is hydrogen, C₁-C₁₂Alkyl or C₆-C₁₈Aryl), or phosphonium cations (e.g. PR)^b ₄ ⁺Wherein each R^bIndependently of one another is hydrogen, C₁-C₁₂Alkyl or C₆-C₁₈Aryl), R¹⁵Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R¹⁶Is a hydrogen atom, a phenyl group or an alkyl group having 1 to 5 carbon atoms, and R¹⁷And R¹⁵Are the same or different and have the same general formula as R¹⁵Are defined identically, provided that R¹⁵、R¹⁶And R¹⁷Are not hydrogen atoms, and m is an integer from 1 to 4, with the proviso that when Y1 is a single bond or an oxygen atom, and with the further proviso that all X of the m amounts¹Not one equivalent of metal cation; has the formula⁺X²-A²-Y¹-SO₃ ^-A compound of (1), wherein A²Is a divalent hydrocarbon group, and is,⁺X²is a secondary, tertiary or quaternary ammonium cation or a secondary, tertiary or quaternary phosphonium cation, and Y¹Is a single bond or an oxygen atom; having the formula A³-(⁺X³)_n·(R-Y¹-SO₃ ^-)_nA compound of (1), wherein A³Is C having a valence n₁-C₄₀A hydrocarbon group,⁺X³as secondary, tertiary or quaternary ammonium cations (e.g. NR)^b ₃ ⁺Wherein each R^bIndependently of one another is hydrogen, C₁-C₁₂Alkyl or C₆-C₁₈Aryl) or secondary, tertiary or quaternary phosphonium cations (e.g. PR)^b ₄ ⁺Wherein each R^bIndependently of one another is hydrogen, C₁-C₁₂Alkyl or C₆-C₁₈Aryl), R is monovalent C₁-C₄₀A hydrocarbon group, n is an integer of 2 to 4, and Y¹Is a single bond or an oxygen atom; having the formula A⁵-Ad¹-A⁴-(Ad²-A⁵)_lA compound of (1), wherein A⁵Is monovalent or divalent C₁-C₄₀A hydrocarbon group A⁴Is divalent C₁-C₄₀Hydrocarbyl, Ad¹And Ad²Each of which is independently selected from-SO₂-O-SO₂-、-SO₂-O-CO-and-CO-O-SO₂An anhydride group of (A), and l is 0 or 1, with the proviso that when l is 0, - (Ad)²-A⁵)_lIs a hydrogen atom or A⁴And A⁵A bond between A⁵Is a divalent hydrocarbon group or a single bond; having the formula R_aR_bN-A-SO₃R_cSulfamate of (1), wherein R_aAnd R_bEach independently is hydrogen, C₁-C₁₂Alkyl radical, C₆-C₂₂Aryl radical, C₇-C₁₉Alkylaryl or R_aAnd R_bForm, alone or in combination, an aromatic or non-aromatic heterocyclic compound (e.g., pyrrolyl, pyridyl, pyrimidinyl, pyrazinyl, carbazolyl, quinolinyl, imidazolyl, piperazinyl, oxazolyl, thiazolyl, pyrazolyl, pyrrolinyl, indolyl, purinyl, pyrrolidinyl, or the like) with N, R_cIs hydrogen and A is C₁-C₁₂Alkyl radical, C₆-C₁₈Aryl or C₁₇-C₁₉Alkaryl groups (e.g., compounds such as N- (2-hydroxyethyl) piperazine-N' -3-propanesulfonic acid, 1, 4-piperazinebis (ethanesulfonic acid), and 5-dimethylamino-1-naphthalenesulfonic acid); having the formula R_aR_bR_cN⁺-A-SO₃ ^-Ammonium sulfonate of (4), wherein R_a、R_bEach independently is hydrogen, C₁-C₁₂Alkyl radical, C₁-C₁₂Aryl radical, C₇-C₁₉Alkylaryl or R_aAnd R_bForm, alone or in combination, an aromatic or non-aromatic heterocyclic compound (e.g., pyrrolyl, pyridyl, pyrimidinyl, pyrazinyl, carbazolyl, quinolinyl, imidazolyl, piperazinyl, oxazolyl, thiazolyl, pyrazolyl, pyrrolinyl, indolyl, purinyl, pyrrolidinyl, or the like) with N, R_cIs hydrogen and A is C₁-C₁₂Alkyl radical, C₆-C₁₈Aryl or C₇-C₁₉An alkaryl group; sulfonated polystyrene; methyl acrylate-sulfonated phenethyl esterAn olefinic copolymer, or a combination comprising at least one of the foregoing.

The branched polycarbonate blocks may be prepared by adding a branching agent during polymerization. These branching agents comprise polyfunctional organic compounds containing at least three functional groups selected from the group consisting of hydroxyl, carboxyl, carboxylic anhydride, haloformyl and mixtures of the foregoing functional groups. Specific examples include trimellitic acid, trimellitic anhydride, trimellitic trichloride, tris (p-hydroxyphenyl) ethane, isatin-bis-phenol, tris-phenol TC (1,3, 5-tris ((p-hydroxyphenyl) isopropyl) benzene), tris-phenol PA (4(4(1, 1-bis (p-hydroxyphenyl) -ethyl) α, α -dimethylbenzyl) phenol), 4-chloroformylphthalic anhydride, trimesic acid, and benzophenone tetracarboxylic acid. The branching agent may be added at a level of 0.05 to 2.0 wt%. Combinations comprising linear polycarbonates and branched polycarbonates may be used.

The thermoplastic composition may also include an impact modifier. Examples of impact modifiers include natural rubber, fluoroelastomers, Ethylene Propylene Rubbers (EPR), ethylene-butene rubbers, ethylene-propylene-diene monomer rubbers (EPDM), acrylate rubbers, hydrogenated nitrile rubbers (HNBR), silicone elastomers, styrene-butadiene-styrene (SBS), styrene-butadiene rubbers (SBR), styrene- (ethylene-butylene) -styrene (SEBS), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-ethylene-propylene-diene-styrene (AES), styrene-isoprene-styrene (SIS), styrene- (ethylene-propylene) -styrene (SEPS), methyl methacrylate-butadiene-styrene (MBS), high Rubber Graft (HRG), and the like.

An additive composition may be used that includes one or more additives selected to achieve desired properties, provided that the one or more additives are also selected to not significantly adversely affect the desired properties of the thermoplastic composition. The additive composition or individual additives may be mixed at a suitable time during the mixing of the components to form the composition. The additives may be soluble or insoluble in the polycarbonate. The additive composition can include an impact modifier, a flow modifier, a filler (e.g., particulate Polytetrafluoroethylene (PTFE), glass, carbon, a mineral, or a metal), a reinforcing agent (e.g., glass fiber), an antioxidant, a heat stabilizer, a light stabilizer, an Ultraviolet (UV) light stabilizer, a UV absorbing additive, a plasticizer, a lubricant, a release agent (such as a mold release agent), an antistatic agent, an antifogging agent, an antimicrobial agent, a colorant (e.g., a dye or pigment), a surface effect additive, a radiation stabilizer, a flame retardant, an anti-drip agent (e.g., a PTFE encapsulated styrene-acrylonitrile copolymer (TSAN)), or a combination comprising one or more of the foregoing. For example, a combination of heat stabilizers, mold release agents, and ultraviolet light stabilizers may be used. Generally, the additives are used in amounts known to be effective. For example, the total amount of the additive composition (excluding any impact modifiers, fillers, or reinforcing agents) can be 0.001 to 10.0 weight percent, or 0.01 to 5 weight percent, each based on the total weight of the polymers in the composition.

Fig. 3 and 4 show embodiments of a method of performing the present process. In fig. 3, for example, stream 108 may be used as the P control point. Because the boiling point of TBPO is close to that of DPC, most of the TBPO will exit distillation column C300 with DPC via overhead stream 109. C300 must have extremely high recovery of DPC and therefore most of the TBPO will accompany the DPC rather than leave the process via stream 108. Without being bound by theory, it is believed that a substantial reduction of color bodies can be achieved so that most of the color bodies will be the reboiler species that are discarded via the column C300 bottoms, while TBPO is recovered along with DPC.

With respect to fig. 4, instead of recovering TBPO and DPC together, TBPO may be recovered as a side draw (stream 110) from the mid-column location. Thus, stream 110 will be rich in P and available for recycle.

The compositions, methods, and articles of manufacture are further illustrated by the following non-limiting examples.

Examples

Phosphorus (P) content was measured using an Agilent ICP-MS (inductively coupled plasma mass spectrometry) model 7700E with a helium mode collision reaction cell. A SeaSpray nebulizer was used in all measurements. The software used to interpret the ICP-MS response is ICP MassHunter^TMWorkstation software.

Samples of Polycarbonate (PC) and diphenyl carbonate (DPC) were prepared as follows: (i) a0.25 gram (g) sample was mixed with 3ml HCl (30 wt%) and 5ml HNO₃(69 wt%)Were added together in duplicate to the digestion flask, (ii) the flask was fixed in a microwave oven at 220 ℃ for 60min, (iii) in 40ml Milli-Q^TMPurified water (Milli-Q produced and distributed by Millipore)^TMWater), (iv) introducing the resulting solution into a suitable Corning tube and subsequently analyzing in an ICP-MS apparatus.

PC and DPC samples have been analyzed by high performance liquid chromatography with diode array detection (HPLC-DAD) under the conditions set forth in table 1. About 2.5g of the sample (PC and DPC material) was dissolved in 7.5ml of Tetrahydrofuran (THF) solution containing 10 wt% potassium hydroxide diluted in methanol. The solution was shaken at 40 ℃ for 20 minutes. Then, 1.5ml of pure acetic acid was added to stop the reaction. The solution was then shaken, filtered and injected into the HPLC system. Suitable standards for preparing calibration curves to determine the concentration of each of the following compounds were prepared, including 4-methylcoumarin, p-isopropenylphenol, o, p-BPA (ortho-and para-bisphenol A), DMX (9,9 dimethylxanthene, CAS: 19814-75-6), and BPX-1:

the water stability test was performed using molded 2.5mm colored non-textured plates placed in an autoclave at 120 ℃ and 100% humidity for 9 days, with daily measurements. The plaques were measured in a BYK transmission hazemeter (BYK haze-gard) according to ASTM D1003 via procedure a and illuminant C to obtain haze and percent transmission results.

For the average (Avg.) measurements provided in the table, the number of samples used for averaging (# S) is provided.

Note that a baseline run as shown in fig. 1 was established prior to all tests.

Tributylphosphine oxide (TBPO) (weight average molecular weight (Mw): 218.32g/mol) and tetrabutylphosphonium acetate (TBPA) (Mw: 318.47g/mol) contents were determined based on the phosphorus content associated with those species. In other words, the measured 1ppm of elemental P represents 7.0ppm TBPO or 10.3ppm TBPA.

The oxidative stability of the polycarbonates prepared by the process described herein was determined using the "patty test". The test consists of heating 50g of polycarbonate pellets in air at a temperature of 250 ℃ for 2 hours. The resulting plate (also known as a "cookie") is also used for color measurement.

With color measurements for optical characterization, flat non-textured colored plaques 2.5mm wide were molded with an ENGEL Victory 120 molding machine using the following conditions: (i) temperature ("Temp") (° c), barrel: 285/290/290/285, and the mold: 75; (ii) injection rate: 90cm³S; (iii) back pressure: 45 bar/10 seconds (4.5 megapascals (mPa)/10 s); (iv) dosage: 105.5cm³(84 mm of 200mm, 251.3cm³42%) rate: 0.293m/s (35% of 0.837 m/s), pressure: 3 bar (0.3 mPa); (v) cooling time: 15 s; and (vi) period: and 40 s.

Color values (L, a, b, and YI) were calculated from the absorbance spectra of the plates (patties) or between 360nm and 750nm using 2.5mm thick colored plates (60 × 60 mm). The spectra were measured in transmission mode on a Macbeth7000A apparatus and included UV. Values for L, a, b and YI have been calculated according to ASTM D1925.

It has been observed that when TBPA is used as a beta catalyst in a polycarbonate production process, TBPO is produced andother phosphoric acid esters of (a).

TBPO is a volatile and can be vaporized under the conditions of the polymerization reaction. During processing, because TBPO has a similar vapor pressure to DPC, for example, a large amount of TBPO can be distilled off with DPC. Thus, TBPO and related phosphate esters produced by the polymerization reaction can be recycled through a recycle loop along with the recovered DPC. Furthermore, it has been unexpectedly observed that an increased amount of TBPA results in higher levels of TBPO and related phosphate esters and makes the resulting polycarbonate less unstable to oxidation reactions due to higher P levels, as has been measured by accelerated oxidation tests ("patty tests"). Table 2 shows the P content (ppm) and patty a values (using 2ppm quencher) for pilot plant runs run operated according to the polycarbonate production process described in example 5 below. The value of a is expected to be-0.3 to-0.4. Thus, the desired P content is from 2 to 10 ppm. Without being bound by theory, higher P content is believed to adversely affect mechanical properties of the polycarbonate, such as water stability.

The DPC impurity content (wt%) of the polycarbonate production process described in examples 1,2 and 3 below is shown in table 3. Example 1 (baseline conditions (BL)) describes an exemplary polycarbonate production process according to an embodiment of the present invention. Example 2 describes an alternative polycarbonate production process in which stream 102 containing TBPO and DPC is directed to a purge tank. Example 3 describes yet another polycarbonate production process in which the recycling of unwanted color-inducing species into the process via a recycle loop has been observed and polycarbonate with an undesirable level of color-inducing species is produced. See table 3 below.

The initial color of the polycarbonate and the color after aging are influenced by the amount of the color-inducing species present. For example, the color inducer can be an isopropenyl-containing compound or 9,9 Dimethylxanthene (DMX). Thus, lower levels of color-inducing species are associated with lower coloration in the polycarbonate and are therefore desirable.

As further detailed in examples 1-5, the inventors have discovered that operational variations of the polycarbonate production process allow for the production of polycarbonates with lower coloration and increased P concentration.

Example 1

Fig. 1 illustrates an exemplary polycarbonate production process. The reactants DPC and BPA were mixed in the monomer mixing unit (R010) in the presence of TBPA. The process stream continues to the first oligomerization reactor (R100). A scrubber (C100) running on top of R100 recycles DPC and BPA back to R100 and removes phenol. The set of equipment (H100, V100) allows condensation of the C100 vapor product and adjustment of the appropriate distillate and reflux rates for C100. The process stream continues to a second oligomerization reactor (R200). The process stream continues to the first polymerization reactor (R300), the second polymerization reactor (R400) and the third polymerization reactor (R500). The train (H200, H300, H400) allows the vapor streams exiting R200, R300, and R400, respectively, to be condensed or sublimated to remove most of the phenol and send those materials to V200. These materials may contain phenol, DPC, BPA, and TBPO produced as well as related phosphate esters. The material then continues to a second scrubber (C200). Phenol is separated from C200 into overhead stream 103. Due to its volatility, TBPO remains in the bottom stream 102 with DPC.

Stream 102 is then fed to two extraction columns (C401 and C402). The two extraction columns are in communication via a bottoms stream 105. The bottoms stream 105 may contain residual phenol, DPC, BPA, TBPO, and other phosphate esters, and the bottoms stream 105 is fed to C402. The top stream (2) of C402 comprises DPC/TBPO recycled to the monomer mixing unit (R010). The bottom stream (107) of C402 is freed of High Boilers (HB).

It has been observed that during the production process described in example 1 and shown in FIG. 1, the P content in DPC is 50-70ppm P in DPC when run at 50 micromoles (. mu.mol) TBPA/mol BPA. Since the ratio of P to TBPO is 31/218(ppm P)/(ppm TBPO), the TBPO content is 350 to 495 ppm. The P content in PC (from TBPO present) under those conditions was 5-10 ppm.

Example 2

Figure 2 shows an alternative polycarbonate production process in which stream 102 containing TBPO and DPC is directed to a purge tank. In this case, all materials from the medium-boiling species (MB) to the high-boiling species (HB) are washed. This reduces recycling of MB, DPC, TBPO and other HB back to the process. In this configuration, the TBPO content in DPC run at 50. mu. mol TBPA/mol BPA was reduced to a large extent to 1-5ppm P.

Table 4 shows the P content in DPC and PC. In the case of PC, it must be taken into account that PC also contains a certain amount of other extrusion stabilizers/processing aids Irgafos^TM168 (tris (2, 4-di-tert-butylphenyl) phosphite, CAS: 31571-04-4, Mw: 646.9 g/mol). Thus, as shown in Table 4, the total P content is not directly affected by the DPC re-route (re-route). The P content (ppm) during the polycarbonate production is shown in FIG. 1. The 2.95% mean Confidence Interval (CI) was calculated using the MS Excel confidence.t function and 0.05 as a. Examples B and D (compared to example a) had improved initial colour (lower B at the pellets) but higher patty a values.

With respect to Table 5, example E had Irgafos as the exception^TMIn addition, it also contains 5ppm of H₃PO₃. Even at those additions, the total P content in PC is in the same order of magnitude as example C and shows a lower initial a. But referring to table 6, it is evident that the water stability of example E is lower compared to example C. As can be seen in table 6, the initial percent transmittance (T%) for examples C and E are similar (92.04 and 92.07, respectively). But the percent transmittance (T%) of example E decreased to 87.99 after 5 days while example C remained at 90.95. This is also shown in the haze values, where example E had a haze of 4.774 after 5 days, while example C had a haze of 2.219. It is clear that merely adding additional additives to increase the P content of the polycarbonate does not result in the improved PC achieved in the present invention using higher P content in the recycle stream. Surprisingly, a different PC was obtained in each case.

Number of samples used to determine the average value (Avg.) # S

¹The number of samples (# S) was 3

BLD is less than detection limit, which is 2ppm

^*2 sample BLD

²The sample also included 5ppm H₃PO₄

And (3) testing the water stability: molded 2.5mm colored non-textured panels were placed in an autoclave at 120 ℃ and 100% humidity for 9 days. The plaques were measured in an Xrite color i7 spectrophotometer to obtain the haze and% transmittance according to ASTM D1003 method.

The low boiling point (LB) species is a species lighter than phenol, MB is a species boiling between that of phenol and DPC, and HB is a species heavier than DPC.

DPC, TBPO and other phosphate esters return to the process is beneficial and desirable for monomer use. Poor oxidative stability of the polycarbonate was also observed due to the reduced concentration of this TBPO and other phosphates. However, this procedure allows for improved colored polycarbonates because the color-inducing species are washed away.

It has been found that the colour inducer content of the monomer mixing stage (R010) is not as high as the colour inducer content at the first oligomerisation reactor (R100) and that the colour inducer content of the second oligomerisation reactor (R200) content is lower than the content at R100. The highest color inducer content is found at R100. The color inducer class content in the scrubber operating on top of R100 shows that the bottom stream that recycles DPC and BPA back to R100 has a higher color inducer class content than either R100 or the scrubber (C100) top stream. The former assumption is that C100 based operation allows very pure recovery of the overhead product, lower reflux ratio and thus other operating conditions that may result in different impurity profiles. In the case of C200, it has been found that most of the colored species will remain in the bottoms, and several colored species may be present in the tops, with the distribution depending on the reflux ratio at which C200 is run. For column C300, table 7 summarizes the observed DPC mass balances, the following mass balances were obtained using column C300 operated without reflux.

Additionally, some color inducer species are MB and can be reduced by, for example, increasing Side Draw (SD) flow. In the case of isopropenylphenol-phenyl carbonate, or in the case of isopropenylphenol dimer, isopropenylphenol trimer or isopropenylphenol oligomer, the separation of those species is more complicated because they are all HB and in some cases are near boilers of DPC.

Thus, the SD stream was found to be desirable during DPC purification and allows for improved TBPO and other related recoveries (e.g., phosphate esters) while reducing the concentration of color inducer species.

Example 3

Figure 3 shows another alternative polycarbonate production process designed to address the reduction in TBPO concentration described in the previous example and shown on figure 2. A new distillation column (C300) is added to recover TBPO and DPC, which are then rerouted back to the process via the top stream (109) of column C300. It has been observed that DPC split ratios greater than 0.6 are required to observe the oxidative benefits in polycarbonates. The main reason for this is that the color benefit is shown in example 2 where the DPC recovery is close to 0.6, but it does not show the P content that would provide the oxidation benefit. The reason for this is that (i) the top of C300 is not sent to C401, resulting in a loss of P content, and (ii) a DPC recovery rate higher than 0.6 is needed to pull more TBPO and other phosphates from the bottom product up to the top product. It has been found that the process described in figure 3 does not increase the TBPO and other phosphate ester content in stream 105. In the case of C300 operation, the P contents observed for DPC split and no reflux operation of 0.6 are those in the next example 4. The feed had 243ppm P, the overhead was 289ppm, and the bottoms was 103 ppm.

These experiments show that TBPO and other phosphate esters can be recovered if appropriate DPC recovery is allowed in a DPC recovery column such as C300.

The data in example 3 discloses that P content can be modified by varying DPC recovery in C300.

Table 8 identifies the P content (ppm) in different streams on a commercial scale, showing DPC/P content variation. The stream numbers refer to the streams shown in figures 1 to 2. Set 1 data references a baseline composition (when run in a configuration as shown in fig. 1). Setting 3 refers to data when rerouting of stream 102 is performed as shown in fig. 2.

According to the process configuration in fig. 3, stream 109 is not directly connected to C401. Thus, the P content in stream 105 is not available. It has been confirmed by GCMS and P31 NMR analysis that the P species in DPC recovery columns C200 and C300 are TBPO and, in addition, TBPO-related phosphate esters are present at low levels due to the volatility of these species.

Example 4

Figure 4 shows another alternative polycarbonate production process in which DPC and TBPO are allowed to exit the C300 as a Side Draw (SD) stream. The side draw stream may be distributed anywhere along the C300 and may remove varying amounts of material. Typically, the SD stream is located at a position along the column concentration profile at which the concentration of the species being withdrawn is highest. This configuration also allows for the washing of the color-inducer species, which may accompany the DPC as shown on figures 2 and 3. Thus, SD (as shown on figure 4) allows groups of species with similar boiling points to be selected for cleaning while returning DPC and TBPO to the process.

Example 5

FIG. 5 shows another alternative polycarbonate production process in which an increased amount of TBPA has been provided into the system to achieve a higher P content. TBPA can be introduced at R010 and later in the process. A decrease in the "patty" value is observed in the polycarbonate as the P content increases.

Table 9 illustrates the operating conditions during TBPA loading on a pilot scale (42 kilograms per hour (kg/h)) as shown in figure 5.

Parts per billion by weight

Table 10 illustrates the P content for the different operating conditions of table 7.

The observed P content set forth in Table 8 is associated with P-containing species that are heavier than TBPO and are species associated with TBPO-related phosphate esters, e.g.Was observed during the degradation study of TBPA in addition to TBPO.

In this configuration with TBPA loading, an increase in alpha catalyst loading is required. For example, 30-44 parts per billion (ppb) increases for 50 μmol TBPA, 80-75ppb increases for 200 μmol TBPA, and 130-140ppb increases for 300 μmol TBPA.

The TBPA loading process as shown in figure 5 reduces the value of the patty a from-0.3 to-0.6 as shown in figure 6. Removal of the quencher increased the cake a values by a similar amount. Table 11 shows the patty a values for the process runs on pilot scale as depicted in fig. 5.

Table 12 shows the b color values of the 2.5mm colored plaques during TBPA loading as shown in figure 5.

The data in tables 11 and 12 show that PC pellets with low TBPA loading show lower a and b color values, but lower P content and thus lower oxidation stability, as shown in table 10. Without being bound by theory, it was found that washing some species in DPC reduced the initial color as measured in the pellets. But those washes also remove P and therefore have a negative effect on the cake value. With TBPA running, it was observed that higher TBPA worsened the panel color, but unexpectedly reduced the patty value. TBPA produces some colored species but contributes to the antioxidant species.

Thus, the processes described in examples 3 and 4 produce overall better results in achieving the desired P content and lower color values. More specifically, in example 3 distillation column C300 is added to the process to recover TBPO and DPC, which are then rerouted back to the process via top stream 109 of column C300. This allows for higher recovery of TBPO and other phosphate esters while allowing for proper DPC recovery in DPC recovery columns such as C300. In example 4, a side draw stream was added, which allowed selective purging of a group of species (i.e., color inducer species) while returning DPC and TBPO to the process. Thus, the procedures described in examples 3 and 4 allow for polycarbonates with the desired oxidative stability due to the higher P content and reduced color.

Example 6

The effect of TBPO on a was determined by adding different amounts of TBPO to the polycarbonate samples. All remaining elements remain the same. The polycarbonate is fed into an extruder. The extruder was set at 25kg/h using a barrel temperature of 280 ℃/290 ℃/300 ℃/300 ℃/300 ℃/300 ℃/295 ℃ and a die temperature of 290 ℃ at 100 revolutions per minute (rpm). After the polymer mass was melted, TBPO was added to the extruder barrel. TBPO was added as a TBPO-containing masterbatch using a TBPO-containing masterbatch. Based on the amount of TBPO added, the amount of P was calculated. The calculated and measured amounts of P are set forth in table 13.

Since TBPO is the only difference between samples A, B and C, any effect on the value of patty a is due to the presence of TBPO. Referring to fig. 7, it can be seen that the polycarbonate without added TBPO has an a of 0.15, while the sample with added TBPO has an a value of about 0.075 and about-0.03. In general, it is desirable to reduce the value of a (red, and therefore make it greener) to allow better color stability of the polycarbonate under oxidant conditions, such as those experienced during the "cake test". Higher beta catalyst loading (e.g., more TBPA loading) resulted in higher b, i.e., more yellow PC (as observed in table 12). Thus, it is expected that higher concentrations of its degradation products (TBPO) will lead to faster degradation (e.g. oxidation leading to a color change, leading to higher b). It was unexpectedly found that with greater amounts of TBPO, the initial color was the same, but the subsequent degradation was better, thereby resulting in better color.

Figure 8 provides b values for 2.5mm colored plaques using TBPO as an additive. The data shows that the initial b color was not significantly modified by the addition of TBPO.

As shown above, better color is achieved with the presence of a small amount of additional P (e.g., 2 to 10ppm, preferably 4 to 10ppm, or 5 to 10ppm) in the PC. This equates to a P content in the recycle stream (or recycle DPC) greater than or equal to 40ppm (e.g., P in TBPO). It is noted that the concentration of P in PC is only increased, such as by adding additional P-containing additives (such as H)₃PO₃) The water stability of PC is adversely affected, while increasing the P concentration using the recycle stream as disclosed herein maintains the water stability properties.

Some aspects of the methods, polycarbonates, and articles are set forth below.

Aspect 1: a method of preparing a polycarbonate composition in a polymerization system, the method comprising: melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst; recycling a phosphorus-containing byproduct having a quaternary phosphonium catalyst or a diaryl carbonate compound or a mixture thereof into the polymerization system; and wherein the recycle stream has a phosphorus concentration (e.g., elemental phosphorus concentration) greater than or equal to 40, preferably greater than or equal to 50 ppm. Aspect 2: the process of aspect 1, wherein the quaternary phosphonium catalyst comprises TBPA, preferably TBPA.

Aspect 2: a method of preparing a polycarbonate composition in a polymerization system, the method comprising: melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst; recycling the TBPO into the polymerization system; and wherein the recycle stream has a TBPO concentration greater than or equal to 280ppm, preferably greater than or equal to 350ppm, such as 280ppm to 3,500ppm, or 280 to 1,750 ppm.

Aspect 3: a method of preparing a polycarbonate composition in a polymerization system, the method comprising: melt polymerizing a dihydroxy compound and a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst; recycling the phosphorus containing by-product to the polymerization system; and wherein the recycle stream has a phosphorus-containing byproduct concentration greater than or equal to 280ppm, preferably greater than or equal to 350ppm, such as from 280ppm to 3,500ppm, or from 280 to 1,750 ppm; and wherein the phosphorus-containing byproduct comprises a phosphate ester having the formula:

aspect 4: the method of any one or more of the preceding aspects, wherein the quaternary phosphonium catalyst is present in an amount of 10 to 500 moles of quaternary phosphonium catalyst per total moles of dihydroxy compound.

Aspect 5: the method of any one or more of the preceding aspects, wherein the further melt polymerizing is in the presence of an ionic catalyst, preferably wherein the ionic catalyst has formula (4):

wherein i + ii + iii + iv is greater than or equal to 16, preferably from 16 to 50 or from 20 to 35; and wherein i is greater than or equal to ii +2 and less than or equal to ii + 20.

Aspect 6: the method of any one or more of the preceding aspects, wherein the polymerization system comprises a monomer mixing unit, an oligomerization section, a polymerization section, and an extraction column that extracts phenol from the oligomerization section and returns the dihydroxy compound, diaryl carbonate compound, or mixture thereof to the oligomerization section, and wherein the polymerization system further comprises a recovery system configured to recycle the phosphorus-containing byproduct having the quaternary phosphonium catalyst or diaryl carbonate compound, or mixture thereof, to the monomer mixing unit via a byproduct stream.

Aspect 7: the method of aspect 6, wherein the byproduct stream comprises phenol, bisphenol a, diphenyl carbonate, tributylphosphine oxide (TBPO) and phosphate esters.

Aspect 8: the method of any one or more of the preceding aspects, wherein the phosphorus-containing byproduct comprises a phosphate ester having the formula:

aspect 9: the process of aspects 6 and 7, wherein the recovery system further comprises a first extraction column and a second extraction column, and wherein the overhead stream of the second extraction column comprises more of 80 to 99 wt% DPC and 200 to 1000ppm wt TBPO.

Aspect 10: the process of aspect 9, wherein the DPC contains 10 to 100ppm, preferably 40 to 100ppm or 50 to 90ppm of TBPO in the recovery system.

Aspect 11: the process of aspects 7-10, wherein the extraction of the phosphorus-containing byproduct with quaternary phosphonium catalyst is by side-feeding one of the extraction columns.

Aspect 12: the method of any one or more of the preceding aspects, wherein the dihydroxy compound is a dihydroxy compound having the formula (I):

wherein R is^aAnd R^bEach independently is halogen, C_1-12Alkoxy or C_1-12An alkyl group; p and q are each independently an integer from 0 to 4; x^aIs substituted or unsubstituted C_3-18A cycloalkylene group; having the formula-C (R)^c)(R^d) C of (A-C)_1-25Alkylene group, wherein R^cAnd R^dEach independently is hydrogen、C_1-12Alkyl radical, C_1-12Cycloalkyl radical, C_7-12Aralkyl radical, C_1-12Heteroalkyl or cyclic C_7-12A heteroaralkyl group; or has the formula-C (═ R)^e) A group of (a) wherein R^eIs divalent C_1-12A hydrocarbyl group; and wherein the diaryl carbonate compound is a diaryl carbonate compound having the formula (a):

wherein each n is independently an integer from 1 to 3; and each RⁱIndependently is a straight or branched chain, optionally substituted C_1-34Alkyl radical, C_1-34Alkoxy radical, C_5-34Cycloalkyl radical, C_7-34Alkylaryl group, C_6-34Aryl, a halogen group OR-C (═ O) OR ', wherein R' is H, straight OR branched C_1-34Alkyl radical, C_1-34Alkoxy radical, C_5-34Cycloalkyl radical, C_7-34Alkylaryl or C_6-34And (4) an aryl group.

Aspect 13: the method of any one or more of the preceding aspects, wherein the recycle stream has a phosphorus concentration of 40 to 500ppm, or 40 to 250ppm, or 50 to 250ppm, preferably 50 to 150ppm, or 50 to 100ppm, and again or 50 to 70 ppm.

Aspect 14: the method of any one or more of the preceding aspects, wherein the quaternary phosphonium catalyst comprises TBPA, preferably TBPA.

Aspect 15: the method of any one or more of the preceding aspects, wherein the dihydroxy compound is BPA and the diaryl carbonate compound is diphenyl carbonate.

Aspect 16: a polycarbonate prepared by the method of any of the preceding aspects.

Aspect 17: an article comprising the polycarbonate composition of aspect 16.

Aspect 18: the article of aspect 17, wherein the article is a sheet, a film, a multilayer sheet, a multilayer film, a molded part, an extruded profile, a fiber, a coated part, or a foam.

The compositions, methods, and articles of manufacture can alternatively comprise, consist of, or consist essentially of any suitable component or step disclosed herein. The compositions, methods, and articles of manufacture may additionally or alternatively be formulated so as to be devoid of or substantially free of any steps, components, materials, ingredients, adjuvants, or species that are not necessary to the achievement of the function or purpose of the compositions, methods, and articles of manufacture.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Unless the context clearly indicates otherwise, "or" means "and/or".

Phosphorus content as used herein was determined using an Agilent ICP-MS (inductively coupled plasma mass spectrometry) model 7700E with a helium mode collision cell. A SeaSpray nebulizer was used in all measurements. The software used to interpret the ICP-MS response is ICP MassHunter^TMWorkstation software.

Unless otherwise indicated, the terms "bottom" or "top" are used herein for convenience of description only and are not limited to any one position or spatial orientation. The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

The endpoints of all ranges directed to the same component or property are inclusive of the endpoint and independently combinable (e.g., ranges of "less than or equal to 25 wt%, or 5 wt% to 20 wt%", is inclusive of the endpoints and all intermediate values of the ranges of "5 wt% to 25 wt%", etc.). The disclosure of a narrower or more specific group than the broader group does not forego the broader or larger group of claims.

The prefix "(s)" is intended to include both the singular and the plural of the term that it modifies, thereby including at least one of that term (e.g., the colorant(s) includes at least one colorant). "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

The term "commercial scale" as used herein means a scaled-up industrial process of polycarbonate production processes (e.g., a polycarbonate production industrial process that can produce about 16,800 kilograms of polycarbonate per hour) that is implemented in an industrial facility, wherein the process was originally developed on a laboratory scale.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. "combination" includes blends, mixtures, alloys, reaction products, and the like.

Unless specified to the contrary herein, all test standards, such as ASTM, ISO, etc., are the latest standards in force as of 12 months and 5 days in 2018.

All cited patents, patent applications (including any patent application to which this application claims priority), and other references are incorporated by reference herein in their entirety. However, in the event that a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

While typical embodiments and aspects have been set forth for the purpose of illustration, the foregoing description should not be deemed to be a limitation on the scope hereof. Accordingly, various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the spirit and scope herein.