KR20050019743A - Method of polycarbonate preparation - Google Patents

Abstract

The present invention relates to a mixed alkali metal salt of phosphoric acid mixed with a promoter such as tetramethylammonium hydroxide (TMAH), which is an excellent transesterification catalyst for the production of polycarbonates from bisphenol A and diphenyl carbonate. Kinetic measurements carried out in a model system consisting of p-t-octylphenol and bis (p-cumylphenyl) carbonate show that this mixed alkali metal phosphate salt is a stronger catalyst than the salt of phosphoric acid containing a single alkali metal ion. This novel catalyst, in addition to providing a higher polymerization rate, polycarbonate with reduced levels of price rearrangement products compared to polymerization catalyzed by conventional catalyst systems such as sodium hydroxide with TMAH promoters. Provided.

Description

Production Method of Polycarbonate {METHOD OF POLYCARBONATE PREPARATION}

The present invention relates to a method for producing a polycarbonate. More specifically, at least one dihydroxy aromatic compound is melt reacted with at least one diaryl carbonate, wherein the melt reaction is mediated by a transesterification catalyst comprising at least one mixed alkali metal salt of phosphoric acid and a promoter. It relates to a method for producing a carbonate.

Typically, polycarbonates are prepared by reacting a dihydroxy aromatic compound such as bisphenol A with phosgene in the presence of an aqueous phase comprising an acid acceptor such as sodium hydroxide and an organic solvent such as dichloromethane. Typically, a phase transfer catalyst such as a quaternary ammonium compound or a low molecular weight tertiary amine (eg triethylamine) is added to increase the rate of polymerization. Such synthesis is commonly known as "interfacial" synthesis for producing polycarbonates.

The interfacial synthesis process for producing polycarbonates has several inherent disadvantages. The first drawback is that from a clear safety standpoint, you have to operate a process that requires phosgene as a reactant. A second drawback is the need to run processes that require the use of large amounts of organic solvents that require expensive precautions to protect against certain adverse environmental impacts. Third, these interfacial synthesis methods require a relatively large amount of equipment and capital investment. Fourth, polycarbonates produced by this interfacial process have proven to have inconsistent colors, high particulate concentrations and high chlorine contents that can cause corrosion.

More recently, polycarbonates have undergone a solvent-free process involving the transesterification of dihydroxy aromatic compounds (eg bisphenol A) and diaryl carbonates (eg diphenyl carbonate) in the presence of a transesterification catalyst. It is manufactured on a commercial scale. The reaction is carried out in a molten state without solvent and completes the reaction by mixing the reactants under reduced pressure and high temperature while simultaneously distilling the phenol byproducts produced by the reaction. This synthesis technique is referred to as the "melt" process. This melting process is superior to the interfacial method because it does not use phosgene, requires no solvent, and uses fewer devices. Moreover, the polycarbonates produced by this melting process do not contain chlorine contaminants from the reactants, have a lower particulate concentration and have a more consistent color. Therefore, it is highly desirable to use melting techniques in the production of polycarbonates in commercial manufacturing processes.

A wide range of transesterification catalysts for use in the production of polycarbonates using melting processes has been evaluated. Alkali metal hydroxides, in particular sodium hydroxide, have been found to be effective as transesterification catalysts. Alkali metal hydroxides, however, are useful as polymerization catalysts, but are also known to promote the Fries reaction as polycarbonate growth results in the production of branched polycarbonate products. The presence of branching sites in the polycarbonate chain results in poor melt flow behavior of the polycarbonate, which can lead to process difficulties.

Thus, it would be desirable to develop a catalyst system effective for melt polymerization while minimizing undesirable reaction products, such as branched side reaction products.

In one aspect, the present invention,

Reacting at least one dihydroxy aromatic compound and at least one diaryl carbonate under melt polymerization conditions in the presence of a transesterification catalyst;

Wherein the transesterification catalyst comprises one or more mixed alkali metal salts of phosphoric acid and one or more promoters comprising quaternary ammonium salts, quaternary phosphonium salts or mixtures thereof

It provides a method for producing a polycarbonate.

In another aspect, the present invention relates to polycarbonates produced by the process of the invention, wherein the level of the price product is lower than the polycarbonates produced by conventional melt polymerization processes.

The invention will be more readily understood by reference to the following detailed description of the preferred embodiments of the invention and the examples included herein. In this specification and claims, various terms having the following meanings are used.

Singular forms include plural relationships unless the scope clearly dictates otherwise.

The terms "optional" or "optionally" mean that the event or environment described subsequently occurs or does not occur, and that this description indicates when an event occurs and when no event occurs. It means to include.

The term "polycarbonate" is a polycarbonate incorporating structural units derived from one or more dihydroxy aromatic compounds, including copolycarbonates and polyester carbonates.

As used herein, the term “melt polycarbonate” refers to a polycarbonate prepared by transesterification of one or more dihydroxy carbonates with one or more diaryl carbonates.

"BPA" is defined herein as bisphenol A or 2,2-bis (4-hydroxyphenyl) propane, 4,4'-isopropylidenediphenol and p, p-BPA.

The term "bisphenol A polycarbonate" refers to a polycarbonate essentially wherein all repeating units comprise bisphenol A residues.

The term "polycarbonate" includes both high molecular weight polycarbonates and oligomeric polycarbonates. High molecular weight polycarbonate is defined as having a number greater than 8000 daltons average molecular weight (M _n), oligomeric polycarbonate is defined as having a number average molecular weight (M _n) of less than 8000 Daltons.

The term "end capping rate (%)" refers to the percentage of the end of the polycarbonate chain that is not a hydroxyl group. When bisphenol A polycarbonate is made from diphenyl carbonate and bisphenol A, about 75% of "end capping rate" is that about 75% of all polycarbonate chain ends including phenoxy groups comprise phenoxy groups, It is meant that about 25% of the chain ends contain hydroxyl groups.

The term "aromatic radical" refers to a radical having at least one valence and comprising at least one aromatic ring. Examples of aromatic radicals include phenyl, pyridyl, furanyl, thienyl, naphthyl, phenylene and biphenyl. The term includes groups containing both aromatic and aliphatic components, such as benzyl groups, phenethyl groups or naphthylmethyl groups. The term also includes groups comprising both aromatic and cycloaliphatic groups, for example 4-cyclopropylphenyl and 1,2,3,4-tetrahydronaphthalen-1-yl.

The term "aliphatic radical" refers to a radical having atoms of at least one valence and consisting of atoms in a linear or branched arrangement that is not a ring. This arrangement may comprise heteroatoms such as nitrogen, sulfur and oxygen or may consist of atoms other than carbon and hydrogen. Examples of aliphatic radicals include methyl, methylene, ethyl, ethylene, hexyl, hexamethylene and the like.

The term “alicyclic radical” refers to a radical having one or more valences, consisting of an cyclic but non-aromatic atomic arrangement and further comprising no aromatic rings. This arrangement may comprise heteroatoms such as nitrogen, sulfur and oxygen or may consist of atoms other than carbon and hydrogen. Examples of cycloaliphatic radicals include cyclopropyl, cyclopentyl, cyclohexyl, 2-cyclohexylethyl-1-yl, tetrahydrofuranyl and the like.

The term "Price product" is included so that the carboxy-substituted dihydroxy aromatic compound upon hydrolysis of the product polycarbonate, wherein the carboxy group is adjacent to one or two hydroxy groups of the carboxy-substituted dihydroxy aromatic compound. It is defined as the structural unit of the product polycarbonate which produces (). For example, when bisphenol A polycarbonate is produced by a melt reaction method in which a price reaction occurs, the price product is a compound having the structural characteristics of the polycarbonate to produce 2-carboxy bisphenol A upon completion of the hydrolysis of the product polycarbonate. It includes.

The terms "Price product" and "Price group" are used interchangeably.

The terms "Price reaction" and "Price rearrangement" are also used interchangeably.

The term "Price Level" refers to the amount of price product present in the product polycarbonate.

As described above, the present invention includes the step of reacting at least one dihydroxy aromatic compound and at least one diaryl carbonate under melt polymerization conditions in the presence of a transesterification catalyst, wherein the transesterification catalyst is formed of phosphoric acid. A method of making a polycarbonate, comprising one or more mixed alkali metal salts and one or more promoters comprising quaternary ammonium salts, quaternary phosphonium salts or mixtures thereof. The mixed alkali metal salt comprises at least two different alkali metal ions selected from the group consisting of cesium ions, sodium ions and potassium ions. The mixed alkali metal phosphate catalyst is easily prepared by adding the first alkali metal hydroxide to the aqueous solution of phosphoric acid and then adding the second alkali metal hydroxide to the mixture. This addition can be titrated to monitor the addition amount of alkali metal hydroxide as the pH change of the phosphoric acid solution. For example, an aqueous solution of phosphoric acid is first treated with about 0.95 equivalents of cesium hydroxide and then with 0.6 equivalents of sodium hydroxide. The resulting aqueous solution contains mixed alkali metal phosphate (CsNaHPO ₄ ), which has been found to exhibit improved catalytic properties over other alkali metal phosphates containing only a single species of alkali metal ions. Typically, the mixed alkali metal phosphate catalyst is added to the polymerization as an aqueous solution. Thus, the preparation and use of the mixed alkali metal phosphate catalyst of the present invention is particularly convenient.

Where the mixed alkali metal phosphate catalyst comprises cesium and sodium ions, the catalytic activity is found to be optimal when the catalyst comprises from about 0.85 to about 1.0 equivalents of cesium and about 0.1 to about 0.6 equivalents of sodium, based on the equivalents of phosphate lost. When the mixed alkali metal phosphate catalyst comprises potassium and sodium ions, the catalytic activity is found to be optimal when the catalyst comprises from about 0.85 to about 1.0 equivalents of potassium and about 0.1 to about 1 equivalents of sodium, based on the phosphoric acid equivalents. lost.

In the case of melt polymerization of at least one dihydroxy aromatic compound and at least one diaryl carbonate, the mixed alkali metal salt of phosphoric acid is typically from about 1 × 10 ⁻⁸ to about 1 × 10 ⁻³ , per mole of dihydroxy aromatic compound, Preferably in an amount of about 1 × 10 ⁻⁶ to about 2.5 × 10 ⁻⁴ .

Dihydroxy aromatic compounds used in accordance with the process of the invention include dihydroxy benzenes such as hydroquinone (HQ), 2-methylhydroquinone, resorcinol, 5-methyllesosocinol and the like; Hydroxy naphthalenes such as 1,4-dihydroxynaphthalene, 2,6-dihydroxynaphthalene and the like; And bisphenols such as bisphenol A and 4,4'-sulfonyldiphenol. Typically, the dihydroxy aromatic compound comprises one or more bisphenols of formula (I):

Where

R ¹ independently of ^one another is a halogen atom, a nitro group, a cyano group, a C ₁ -C ₂₀ alkyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₆ -C ₂₀ aryl group;

n and m are independently integers from 0 to 4;

W is a bond, oxygen atom, sulfur atom, SO ₂ group, C ₁ -C ₂₀ aliphatic radical, C ₆ -C ₂₀ aromatic radical, C ₆ -C ₂₀ alicyclic radical or formula Wherein R ² and R ³ are independently a hydrogen atom, a C ₁ -C ₂₀ alkyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₄ -C ₂₀ aryl group; or R ² and R ³ together form one or more Form a C ₄ -C ₂₀ alicyclic ring, optionally substituted with a C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryl, C ₅ -C ₂₁ aralkyl, C ₅ -C ₂₀ cycloalkyl group, or mixtures thereof Is).

Bisphenols having Formula I include bisphenol A; 2,2-bis (4-hydroxy-3-methylphenyl-propane; 2,2-bis (3-chloro-4-hydroxyphenyl) propane; 2,2-bis (3-bromo-4-hydroxy Phenyl) propane; 2,2-bis (4-hydroxy-3-isopropylphenyl) propane; 1,1-bis (4-hydroxyphenyl) chlorohexane; 1,1-bis (4-hydroxy-3 -Methylphenyl) cyclohexane, exemplified by 1,1-bis (4-hydroxyphenyl) -3,3,5-triethylchlorohexane and the like.

Typically, the diaryl carbonates used are one or more diaryl carbonates having the formula II:

Where

R ⁴ is independently a halogen atom, nitro group, cyano group, C ₁ -C ₂₀ alkyl group, C ₁ -C ₂₀ alkoxy carbonyl group, C ₄ -C ₂₀ cycloalkyl group or C ₆ -C ₂₀ aryl group;

t and v are independently integers from 0 to 5.

Diaryl carbonates (Compound II) include diphenyl carbonate, bis (4-methylphenyl) carbonate, bis (4-chlorophenyl) carbonate, bis (4-fluorophenyl) carbonate, bis (2-chlorophenyl) carbonate, bis ( 2,4-difluorophenyl) carbonate, bis (4-nitrophenyl) carbonate, bis (2-nitrophenyl) carbonate, bis (methylsalicyl) carbonate, and the like.

The transesterification catalyst used in accordance with the process of the invention is from about 1 × 10 ⁻⁶ to about 1 × 10 ⁻² , preferably from about 1 × 10 ⁻⁵ to 2.5 × 10 ⁻⁴ moles per mole of dihydroxy aromatic compound used At least one promoter present in an amount of. Typically, the promoter is one or more quaternary ammonium salts, one or more quaternary phosphonium salts or mixtures thereof.

In one embodiment of the invention, the promoter is a quaternary ammonium compound having Formula III:

Where

R ⁵ to R ⁸ are independently a C ₁ -C ₂₀ alkyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₄ -C ₂₀ aryl group;

X ⁻ is an organic or inorganic anion.

Anion X ⁻ is typically selected from the group consisting of hydroxides, halides, carboxylates, phenoxides, sulfonates, sulfates, carbonates and bicarbonates. Hydroxide is often preferred. Quaternary ammonium salts having Formula III are exemplified by tetramethylammonium hydroxide, tetrabutylammonium hydroxide and the like.

In an alternative embodiment of the invention, the promoter is a quaternary phosphonium compound having Formula IV:

Where

R ⁹ to R ¹² are independently C ₁ -C ₂₀ alkyl groups, C ₄ -C ₂₀ cycloalkyl groups or C ₄ -C ₂₀ aryl groups;

X ⁻ is an organic or inorganic anion.

Anion X ⁻ is typically selected from the group consisting of hydroxides, halides, carboxylates, phenoxides, sulfonates, sulfates, carbonates and bicarbonates. Hydroxide is often preferred. Quaternary phosphonium salts having Formula IV are exemplified by tetrabutylphosphonium hydroxide, tetraoctylphosphonium hydroxide, tetrabutylphosphonium acetate and the like.

In the structures of formulas III and IV, the anion X ⁻ is typically an anion selected from the group consisting of hydroxides, halides, carboxylates, phenoxides, sulfonates, sulfates, carbonates and bicarbonates. It is to be understood that for transesterification catalysts comprising cocatalysts having formulas (III) and (IV), wherein X ⁻ is a polyvalent anion such as carbonate or sulfate, the positive and negative charges in formulas (III) and (IV) are suitably balanced. For example, in tetrabutylphosphonium carbonate (wherein R ⁹ to R ¹² in formula IV are each a butyl group and X ⁻ is represented by a carbonate anion), X ⁻ is represented by 1/2 (CO ₃ ⁻² ) do.

The term "melt polymerization conditions" means the conditions necessary for the effective reaction of diaryl carbonates and dihydroxy aromatic compounds in the presence of a transesterification catalyst. The reaction temperature is typically in the range of about 100 to about 350 ° C, more preferably about 180 to 310 ° C. The pressure in the initial stage of the reaction may be atmospheric, above atmospheric or atmospheric pressure to about 15 torr, and in the late stage, the pressure may be reduced to about 0.2 to about 15 torr. The reaction time is generally about 0.1 to about 10 hours.

The process of the invention can be carried out in a batch process or in a continuous process. In either case, the melt polymerization conditions used are formed in two or more different reaction processes, such as a first reaction process in which the starting diaryl carbonate and the dihydroxy aromatic compound are converted to an oligomeric polycarbonate, and in the first process. And a second reaction process in which the oligomeric polycarbonate is converted to high molecular weight polycarbonate. Such “stepwise” polymerization reaction conditions are suitable for use in continuous polymerization systems in which the starting monomers are oligomerized in a first reaction vessel and the oligomeric polycarbonates formed are continuously delivered to one or more downstream reactors where they are converted to high molecular weight polycarbonates. Especially suitable. Typically, the oligomeric polycarbonates produced in the oligomerization process have a number average molecular weight of about 1000 to about 7500 daltons. In one or more subsequent polymerization processes, the number average molecular weight of the polycarbonate is increased to about 8000 to about 25000 daltons.

In one embodiment, the process is carried out in a two step process. In a first step of this embodiment, a promoter, for example tetramethylammonium hydroxide, is introduced into a reaction system comprising a dihydroxy aromatic compound and a diaryl carbonate. The first step is carried out at temperatures of up to 270 ° C., preferably from about 150 to about 250 ° C., more preferably from about 150 to 230 ° C. The duration of the first stage is from about 2 minutes to about 5 hours, more preferably from about 2 minutes to about 3 hours at atmospheric pressure to 100torr. It is generally desirable to exclude oxygen from the reaction mixture during oligomerization and subsequent polymerization processes. Oxygen exclusion can be conventionally achieved using known techniques, for example, by maintaining a positive pressure of nitrogen in the system before and after evaporation.

Mixed alkali metal salts of phosphoric acid may be added to the first process with a promoter. Optionally a mixed alkali metal salt of phosphoric acid is introduced into the product resulting from the first process and a further polycondensation reaction is carried out. The salts of the mixed alkali metal salts of phosphoric acid may be added in whole to the second process such that the total amount is within the above range, or may be added separately to the second and subsequent processes.

In the second and subsequent steps of the polycondensation step, the reaction temperature is preferably higher than in the first step, but the reaction pressure is low. Typically, in the later stages of the polymerization reaction, the reaction mixture is heated at a temperature of about 240 to 320 ° C. under a reduced pressure of about 5 mmHg or less, preferably 1 mmHg or less.

In one embodiment of the present invention, at least one dihydroxy aromatic compound and at least one diaryl carbonate are reacted in the presence of a transesterification catalyst under melt polymerization conditions in the presence of a branching agent capable of producing a branched product polycarbonate. . Typically, the branching agent may be trisphenol, such as 1,1,1-tris (4-hydroxyphenyl) ethane, THPE. Other branching agents suitable for use in the process of the invention include triacids such as trimellitic acid, 9-carboxyoctadecanedioic acid and the corresponding phenyl esters thereof. Typically, branching agents are used in amounts of about 0.001 to about 0.03 moles per mole of dihydroxy aromatic compound.

In addition, the process of the present invention may be carried out in the presence of an endcapping agent. Accordingly, at least one transesterification catalyst comprising at least one endcapping agent, at least one dihydroxy aromatic compound, at least one diaryl carbonate, and at least one mixed alkali metal salt of phosphoric acid and at least one promoter is subjected to melt polymerization conditions. Reacting to provide a product polycarbonate comprising end groups derived from endcapping agents. Typically, endcapping agents are monofunctional phenols such as cardanol, p-cresol, p-t-butylphenol, and p-cumylphenol. For example, when p-t-butylphenol is used as an endcapping agent, the product polycarbonate prepared according to the present invention comprises a terminal p-t-butylphenoxy group.

In some embodiments, the process of the present invention is superior to the initial melt polymerization process based on the rate at which the polymerization reaction occurs under the influence of the mixed alkali metal phosphate catalyst and the promoter bonds used. Thus, high molecular weight product polycarbonates are obtained in a short time. In addition, the product polycarbonates prepared according to the process of the invention typically have a lower level of price product than the product polycarbonates prepared under comparable conditions of reaction time, reaction temperature, catalyst loading using conventional catalyst systems. . In general, a large amount of price is provided as a location for unregulated polymer branches that can cause discoloration and affect the melt flowability of the product polycarbonate, thus limiting the amount of the widest possible price present in the product polycarbonate. It is desirable to. Generally, the amount of price rearrangement product in the high molecular weight polycarbonate prepared according to the method of the present invention is less than about 100 ppm, preferably less than 500 ppm.

It is understood that especially for the type of melting reaction present in the present invention, the monomers used can strongly influence the properties of the product carbonate. Thus, it is often desirable that the monomers used contain no or only very small amounts of contaminants such as metal ions, halide ions, acidic contaminants and other organic species. This may be particularly ideal in applications such as optical discs (eg compact discs) where contaminants present in polycarbonate can affect disc performance. Typically the concentration of metal ions, such as zinc, nickel, cobalt, sodium and potassium, present in the monomers should be less than about 10 ppm, preferably less than about 1 ppm, more preferably less than about 100 ppm. The amount of halide ions, such as fluorine, chlorine and bromine ions, present in the polycarbonate should be minimized to inhibit water absorption by the product polycarbonate and to avoid the corrosive effects of the halide ions on the equipment used to make the polycarbonate. . Certain applications, such as optical discs, may require very small amounts of halide ion contaminants. Preferably, the amount of halide ions present in each monomer used should be less than about 1 ppm. Since only a small amount of base catalyst is used in the oligomerization process and subsequent polymerization processes, the presence of acidic impurities such as organic sulfonic acids, which may be present in bisphenols such as BPA, should be minimized. Even small amounts of acidic impurities can neutralize a significant portion of the underlying cocatalysts and thus have a great effect on the rate of oligomerization and polymerization. Finally, the tendency to fade polycarbonate with high temperature, for example, loss of molecular weight and discoloration during molding, is closely associated with the presence of contaminant species in the polycarbonate. In general, the purity of the product polycarbonate prepared using the melting reaction method as in the present invention closely reflects the purity of the starting monomers.

The polycarbonates produced by the process of the present invention may be optionally blended with any conventional additives to facilitate the formation and use of shaped articles. Common additives include, but are not limited to, UV stabilizers, antioxidants, heat stabilizers, and release agents. In particular, it is desirable to form blends of polycarbonates produced by the process of the invention and additives which serve as processing aids during the molding process and impart additional stability on the molded article. The blend may optionally comprise from about 0.0001 to about 10 weight percent of the preferred additives, preferably from about 0.0001 to about 1.0 weight percent of the desired additives.

Materials or additives that may be added to the polycarbonate of the present invention include heat resistant stabilizers, UV absorbers, mold release agents, antistatic agents, slippers, antiblocking agents, lubricants, anti-clouding agents, colorants, natural oils, synthetic oils, waxes, organic fillers. , Inorganic fillers and mixtures thereof, but is not limited thereto.

Examples of the above heat resistant stabilizers include, but are not limited to, phenol stabilizers, organic thioether stabilizers, organic phosphite stabilizers, hindered amine stabilizers, epoxy stabilizers, and mixtures thereof. Heat resistant stabilizers can be added in solid or liquid form.

Examples of UV absorbers include, but are not limited to, salicylic acid UV absorbers, benzophenone UV absorbers, benzotriazole UV absorbers, cyanoacrylate UV absorbers, and mixtures thereof.

Examples of release agents include natural and synthetic paraffins, polyethylene waxes, fluorocarbons, and other hydrocarbon release agents; Stearic acid, hydroxystearic acid and other high fatty acids, hydroxyfatty acid and other fatty acid release agents; Stearic acid amide, ethylenebisstearamide and other fatty acid amides, alkylenebisfatty acid amides and other fatty acid amide release agents; Stearyl alcohol, cetyl alcohol and other aliphatic alcohols, polyhydric alcohols, polyglycols, polyglycerols and other alcohol release agents; Butyl stearate, pentaerythritol tetrastearate and other lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, polyglycol esters of fatty acids and other fatty acid ester release agents; Silicone oils and other silicone release agents; And any mixtures thereof.

The colorant may be a pigment or a dye. In the present invention, the inorganic colorant and the organic colorant may be used alone or in combination.

The following examples are not intended to provide a detailed description of the methods of the art to perform and evaluate the methods claimed herein and to limit the scope of what the inventors regard as their invention. Unless stated otherwise, parts are parts by weight and temperature is ° C.

Molecular weights are described as number average (M _n ) or weight average (M _w ) molecular weights and measured by gel osmosis chromatography (GPC) compared to polycarbonate standards of known molecular weight.

The price content is measured by the KOH of the resin and reported as ppm. The price content was determined as follows. First, 0.50 g of the product polycarbonate was dissolved in 4.0 ml of THF (containing p-terphenyl as internal standard). Next, 3.0 ml of 18% KOH in methanol was added to this solution. The resulting mixture was stirred at rt for 2 h. Next, 1.0 ml of acetic acid was added and the mixture was stirred for 5 minutes. Potassium acetate byproduct was crystallized for 1 hour. The solid was filtered off and the resulting filtrate was analyzed by liquid chromatography (HPLC) using p-terphenyl as internal standard.

A catalyst solution containing a mixed alkali metal salt of phosphoric acid was prepared by titrating a solution of phosphoric acid with two solutions of alkali metal hydroxides. For example, a phosphoric acid solution (1 × 10 ⁻³ mol H ₃ PO ₄ per liter) was treated with 0.85 to 0.95 equivalents of cesium hydroxide using an aqueous solution of CsOH (1 × 10 ⁻¹ mol CsOH per liter). Then, from 0 to about 1 equivalent of sodium hydroxide or potassium hydroxide was added to the resulting solution. An aqueous NaOH or KOH solution was added with a concentration of about 1 × 10 ⁻¹ mole of NaOH or KOH per liter. The pH of the catalyst solution was then recorded. A catalyst solution comprising a mixed alkali metal salt of CsNaHPO ₄ or CsKHPO ₄ , phosphoric acid was used in the melt polymerization reaction to form polycarbonate.

The reaction was carried out in a 1 liter glass batch reactor equipped with a solid nickel spiral stirrer. The inner surface of the glass reactor was immersed in diluted hydrochloric acid overnight and the reactor was thoroughly rinsed with deionized water (18 mega-Ohms) and passivated by drying overnight at 70 ° C. in a drying oven. During the polymerization reaction the reactor was heated to a fluidized sand bath with a PID controller. The temperature of the reactor was measured outside of the reactor near the interface between the reactor wall and the sand bath. The reactor was equipped with a distillation head and a receiving vessel. The internal pressure of the reactor was regulated through nitrogen bleed to a vacuum pump connected to a receiving vessel via a cold trap. Higher pressures (760 mmHg to 40 mmHg) were measured with a mercury barometer and lower pressures (40 mmHg to 1 mmHg) were measured with an Edward pirani meter. The reactor was charged with 0.6570 moles of BPA and 0.7096 moles of diphenyl carbonate, and the reactor was emptied and then purged with nitrogen by introducing nitrogen gas. This nitrogen washing process was repeated three times. After the final nitrogen exchange, the reactor was brought to approximately atmospheric pressure under nitrogen and submerged in a fluidized bath at 180 ° C. After 5 minutes, stirring was started at 250 rpm. After another 10 minutes, the reaction was sufficiently melted and the mixture was homogenized. Mixed alkali metal salts of phosphoric acid catalyst (1.00 × 10 ⁻⁶ moles per mole BPA) and tetramethylammonium hydroxide cocatalyst (TMAH, 2.4 × 10 ⁻⁴ moles per mole BPA) were added sequentially as an aqueous solution. The added volume of the solution of the mixed alkali metal salt of the phosphoric acid catalyst was about 600 μl. The volume of the solution of the tetramethylammonium hydroxide promoter was about 148 μl. Timing was started when the addition of catalyst and cocatalyst was completed and the temperature was raised to 240 ° C. for 5 minutes. When the temperature reached 240 ° C., the pressure in the reactor was reduced to 180 mm Hg. As the pressure decreased the phenol began to distill. After 25 minutes, the pressure was reduced back to 100 mm Hg and the reaction mixture was maintained at 240 ° C. and 100 mm Hg for 45 minutes. The temperature was then raised to 260 ° C. for 5 minutes and the pressure was further reduced to 15 mm Hg. The reaction mixture was kept at 260 ° C. and 15 mm Hg for 45 minutes. The temperature was then raised to 270 ° C. for 5 minutes and the pressure reduced to 2 mmHg. This condition was maintained for 10 minutes. The temperature was then raised to the last "final temperature" for 5 minutes and the pressure was reduced to 1.1 mm Hg. Final temperatures ranged from about 280 ° C. to about 310 ° C. (see table). After 30 minutes, the reactor was removed from the sand bath and the shaped product polycarbonate was poured into liquid nitrogen and the reaction was stopped.

Unless stated otherwise, a mixed alkali metal salt of 1.0 × 10 ⁻⁶ moles of phosphoric acid catalyst per mole BPA was added and 2.5 × 10 ⁻⁴ moles of TMAH per mole BPA.

Comparative Examples 1 to 6

In Comparative Examples 1 to 6, the catalyst was a cesium phosphate solution prepared by titration with a 1 × 10 ⁻³ molar phosphoric acid aqueous solution containing 0.1 mole of cesium hydroxide (CsOH). The pH of the catalyst solution and the number of equivalents of cesium ions vary. In Comparative Examples 1 to 6 the polymerization was carried out as described in the general experimental technique. TMAH (2.5 × 10 ⁻⁴ moles per mole BPA) was used as promoter. The data in Table 1 illustrate the effect of increasing cesium ion concentration on the polymerization rate (determined by the molecular weight of the product polycarbonate) and the price level in the product polycarbonate.

Comparative Examples 7 to 12

Comparative Examples 7 to 12 were catalysts composed of sodium hydroxide (1 × 10 ⁻⁶ moles per mole BPA) and TMAH cocatalyst (2.5 × 10 ⁻⁴ moles per mole BPA) as compared to Comparative Examples 1-6 and Examples 1 through 32 It illustrates the behavior of the system. The polymerization was tested as described in the general experimental technique using sodium hydroxide instead of mixed alkali metal salts of the phosphate catalyst of the present invention. The last "final temperature" is shown in Table 2.

As can be seen by comparing the data in Tables 1 and 2, the use of cesium (CE-3, catalyst solution pH = 3.72) in excess of 0.94 equivalents does not provide an advantage with respect to price selectivity over sodium hydroxide. . By using an aqueous solution of phosphoric acid and a catalyst solution prepared from not more than 0.94 equivalents of cesium hydroxide (Comparative Examples 1 to 3), the amount of the resulting price product can be lowered, but the overall polymerization rate is lowered, resulting in a lower molecular weight product polycarbonate. do. High molecular weight polycarbonates can be achieved using aqueous solutions of phosphoric acid and catalyst solutions prepared from more than 0.94 equivalents of cesium hydroxide (Comparative Examples 4-6), but as the molecular weight of the product polycarbonate increases the level of the price product Increases.

Examples 1 to 32

Data for melt polymerization with mixed sodium-cesium salts of phosphoric acid are shown in Table 3 below. The data presented in the comparative examples along with Examples 1-15 illustrate the synergistic effect of sodium ions in catalyst systems made from cesium hydroxide and phosphoric acid, “cesium phosphate”.

Data for melt polymerization using mixed sodium-potassium salts of phosphoric acid are presented in Table 4 below. The data presented in Examples 16-32 and Comparative Examples illustrate the synergistic effect of sodium ions in a catalyst system, “potassium phosphate,” prepared from potassium hydroxide and phosphoric acid.

The data in Tables 3 and 4 illustrate the reaction temperature as well as the efficiency of mixed alkali metal salts of phosphoric acid in melt polymerization depending on the alkali metal used. Comparative Example 17 illustrates the behavior of a catalyst prepared by treating an aqueous phosphoric acid solution with 1 equivalent of potassium hydroxide (KH ₂ PO ₄ ). Thus, KH ₂ PO ₄ (pH 4.8) At the stoichiometric equivalent point for salt formation, the catalyst is inefficient as a melt polymerization catalyst even in the presence of a promoter (TMAH). Similarly, NaH ₂ PO ₄ is inefficient as a melt polymerization catalyst in the presence of tetramethylammonium hydroxide (TMAH) or tetrabutylphosphonium hydroxide cocatalyst even when the final final temperature of up to 310 ° C. is used. Of the simple single alkali metal phosphates, NaH ₂ PO ₄ , KH ₂ PO ₄ , and CsH ₂ PO ₄ , only a single cesium salt is effective as a polymerization catalyst compared to sodium hydroxide (Table 2 compared to Comparative Example 12 in Table 2). See Comparative Examples 3 to 6 of 1). In the discovery experimental range, the dipotassium salt (K ₂ PO ₄ ) provided good polymerization rates even though the disodium salt of phosphoric acid was ineffective as a polymerization catalyst under the melt reaction conditions described herein. As illustrated in the examples in Tables 3 and 4, when the ratio of cesium hydroxide or potassium hydroxide to phosphoric acid is appropriately adjusted and about 0.1 equivalent to about 1.0 equivalent of sodium hydroxide is added to the catalyst solution High reaction rates and low price levels can be achieved. The equivalent of sodium hydroxide is referenced to phosphoric acid. One equivalent of sodium hydroxide corresponds to one mole of sodium hydroxide per mole of phosphoric acid. In the experiments presented herein, the ratio of cesium hydroxide or potassium hydroxide to phosphoric acid reflects the initial pH of the mixture prepared from aqueous phosphoric acid and cesium hydroxide or potassium hydroxide ("catalysts in Tables 3 and 4"). Paragraph entitled "The pH of the solution"). The use of cesium salts is optimal when cesium hydroxide is used in less than 1 equivalent to prepare an initial catalyst solution (cesium phosphate solution). 0.1 to about 0.6 equivalents of NaOH is added to the initial catalyst solution to provide a mixed alkali metal phosphate containing both sodium and cesium ions. Use of mixed alkali metal phosphate catalysts yields high molecular weight product polycarbonates containing reduced levels of price products (eg, Comparative Examples 15, Comparative Examples 3 and 12 in Table 3) and keeps the price product production to a minimum While the polymerization rate is maximized.

The potassium salt (Table 4) is believed to be a catalyst that exhibits lower activity than the original cesium salt originally characterized in Table 3, producing a mixed alkali metal phosphate catalyst that is somewhat richer in sodium ions in the corresponding catalyst of Table 3 having the same activity. Useful synergy is noted when adding slightly higher amounts of sodium hydroxide. Finally, the level of the price product reflecting the product polycarbonate molecular weight as well as the "final temperature" (ie, final polymerization temperature) used in the polymerization reaction should be recorded.

Transesterification Kinetic Model System

A series of kinematic measurements of the model reaction system was performed to investigate the intrinsic catalyst activity of the mixed alkali metal phosphate catalyst. No promoter was used in this model reaction. Rate constants and activation energies for several catalyst system activities used in the present invention were evaluated. All glassware used in the kinetics studies were washed with dilute aqueous hydrochloric acid solution, rinsed with deionized water, soaked in deionized water for 12 hours and then dried. Para-tert-octylphenol (“OP”) was recrystallized three more times from hot hexane (1 g: 10 mL). Bis (p-cumylphenyl) carbonate (“PCPC”) was recrystallized from the minimum amount of ethanol boiled. For 5 minutes at 240 ° C. and 15 minutes at 220 ° C., the “OP” and “PCPC” were heated to investigate the purity of the octylphenol by heating the 2: 1 molar mixture, followed by HPLC analysis of the reaction mixture. Purity of octylphenol was considered sufficient if the conversion of the starting material to transesterification cross products (p-cumylphenyl 4-t-octylphenyl) carbonate and bis (4-t-octylphenyl) carbonate was less than 1%.

Catalyst samples were prepared in liquefied phenol (ie, volume ratio of phenol: H ₂ O mixture = 9: 1). Kinetic measurements were performed with CsH ₂ PO ₄ + 0.6 equiv. NaOH (240 ° C.). Samples of pt-octylphenol (1.86 g, 9.0 mM) and bis (p-cumylphenyl) carbonate (PCPC) were added dropwise to a single-neck round bottom flask. The reaction vessel was then washed with nitrogen and immersed in a pre-equilibrated silicone oil bath at 240 ° C. for 5 minutes. An "time 0" aliquot was then pipetted and then the catalyst solution was added by syringe (45 [mu] l of 2 mM solution, 20 ppm based on PCPC). Samples were taken periodically for a 40 minute reaction time and analyzed by HPLC. The data show that the mixed alkali metal phosphate catalyst of the present invention exhibits a higher rate constant compared to a catalyst comprising only cesium phosphate.

Table 6 below provides similar kinetic data for mixed alkali metal phosphate catalysts comprising potassium and sodium. As shown in Table 5, the data show that mixed alkali metal phosphates exhibit greater intrinsic catalytic activity compared to salts of phosphoric acid containing only alkali metal ions.

Although the present invention has been described in more detail with reference to particularly preferred embodiments, it should be understood that changes and modifications may be effective within the spirit and scope of the invention.

Claims (43)

Reacting at least one dihydroxy aromatic compound and at least one diaryl carbonate under melt polymerization conditions in the presence of a transesterification catalyst, Wherein the transesterification catalyst comprises one or more mixed alkali metal salts of phosphoric acid and one or more promoters comprising quaternary ammonium salts, quaternary phosphonium salts or mixtures thereof Method for producing polycarbonate. The method of claim 1, The mixed alkali metal salt comprises at least two alkali metal ions selected from the group consisting of cesium, sodium and potassium alkali metal ions. The method of claim 2, Wherein the salt comprises from about 0.85 to about 1.0 equivalents of cesium and from about 0.1 to about 0.6 equivalents of sodium based on the equivalent of phosphate. The method of claim 1, A process for producing a polycarbonate, wherein the mixed alkali metal salt comprises potassium and sodium ions. The method of claim 4, wherein Wherein the salt comprises from about 0.85 to about 1 equivalent of potassium and from about 0.1 to about 1.0 equivalents of sodium based on the equivalent of phosphate. The method of claim 1, A process for producing a polycarbonate, wherein a mixed alkali metal salt of phosphoric acid is used in an amount of 1 × 10 ⁻⁸ to 1 × 10 ⁻³ mole per mole of dihydroxy aromatic compound. The method of claim 1, A process for preparing a polycarbonate wherein the dihydroxy aromatic compound is a bisphenol of formula (I) Formula I Where R ¹ independently of ^one another is a halogen atom, a nitro group, a cyano group, a C ₁ -C ₂₀ alkyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₆ -C ₂₀ aryl group; n and m are independently integers from 0 to 4; W is a bond, oxygen atom, sulfur atom, SO ₂ group, C ₁ -C ₂₀ aliphatic radical, C ₆ -C ₂₀ aromatic radical, C ₆ -C ₂₀ alicyclic radical or formula Wherein R ² and R ³ are independently a hydrogen atom, a C ₁ -C ₂₀ alkyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₄ -C ₂₀ aryl group; or R ² and R ³ together form one or more Form a C ₄ -C ₂₀ alicyclic ring, optionally substituted with a C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryl, C ₅ -C ₂₁ aralkyl, C ₅ -C ₂₀ cycloalkyl group, or mixtures thereof Is). The method of claim 7, wherein Bisphenol is bisphenol A; 2,2-bis (4-hydroxy-3-methylphenyl) propane; 2,2-bis (3-chloro-4-hydroxyphenyl) propane; 2,2-bis (3-bromo-4-hydroxyphenyl) propane; 2,2-bis (4-hydroxy-3-isopropylphenyl) propane; 1,1-bis (4-hydroxyphenyl) cyclohexane; 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane; And 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane. The method of claim 1, A process for preparing polycarbonate, in which the diaryl carbonate has the structure of Formula II: Formula II Where R ⁴ independently of one another is a halogen atom, a nitro group, a cyano group, a C ₁ -C ₂₀ alkyl group, a C ₁ -C ₂₀ alkoxy carbonyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₆ -C ₂₀ aryl group ego; t and v are independently integers from 0 to 5. The method of claim 9, Diaryl carbonates are diphenyl carbonate, bis (4-methylphenyl) carbonate, bis (4-chlorophenyl) carbonate, bis (4-fluorophenyl) carbonate, bis (2-chlorophenyl) carbonate, bis (2,4- A method for producing a polycarbonate, wherein the polycarbonate is selected from the group consisting of difluorophenyl) carbonate, bis (4-nitrophenyl) carbonate, bis (2-nitrophenyl) carbonate and bis (methylsalicyl) carbonate. The method of claim 1, A process for preparing polycarbonate, wherein the quaternary ammonium compound has the structure of Formula III: Formula III Where R ⁵ to R ⁸ are independently a C ₁ -C ₂₀ alkyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₄ -C ₂₀ aryl group; X ⁻ is an organic or inorganic anion. The method of claim 11, A process for producing a polycarbonate, wherein the anion is selected from the group consisting of hydroxides, halides, carboxylates, phenoxides, sulfonates, sulfates, carbonates and bicarbonates. The method of claim 11, The quaternary ammonium compound is tetramethylammonium hydroxide. The method of claim 1, A process for preparing a polycarbonate, wherein the phosphonium compound has the structure of Formula IV: Formula IV Where R ⁹ to R ¹² are independently C ₁ -C ₂₀ alkyl groups, C ₄ -C ₂₀ cycloalkyl groups or C ₄ -C ₂₀ aryl groups; X ⁻ is an organic or inorganic anion. The method of claim 14, A process for producing a polycarbonate, wherein the anion is selected from the group consisting of hydroxides, halides, carboxylates, phenoxides, sulfonates, sulfates, carbonates and bicarbonates. The method of claim 14, The quaternary phosphonium compound is tetrabutylphosphonium hydroxide. The method of claim 1, Wherein the reaction of at least one dihydroxy aromatic compound and at least one diaryl carbonate under melt polymerization conditions in the presence of a transesterification catalyst is carried out in the presence of at least one branching agent. The method of claim 17, The branching agent is 1,1,1-tris (4-hydroxyphenyl) ethane, The manufacturing method of the polycarbonate. The method of claim 1, Wherein the reaction of at least one dihydroxy aromatic compound and at least one diaryl carbonate under melt polymerization conditions in the presence of a transesterification catalyst is carried out in the presence of at least one endcapping agent. The method of claim 19, The end capping agent is a hydroxy aromatic compound. The method of claim 20, The hydroxy aromatic compound is selected from the group consisting of phenol, p-t-butylphenol, p-cumylphenol and cardanol. The method of claim 1, The method of making a polycarbonate, wherein the product polycarbonate contains less than about 1000 ppm Fries product. The method of claim 1, Method for producing a polycarbonate in a continuous process. Process for producing polycarbonate which is a batch process. Contacting at least one dihydroxy aromatic compound with at least one diaryl carbonate under melt polymerization conditions in the presence of a transesterification catalyst, The transesterification catalyst comprises one or more mixed alkali metal salts of phosphoric acid and one or more promoters comprising quaternary ammonium salts, quaternary phosphonium salts or mixtures thereof, Wherein said contacting is carried out in two or more processes, Method for producing polycarbonate. The method of claim 25, Contacting, Oligomerization process to produce oligomeric polycarbonates having a number average molecular weight of about 1000 to about 7500 daltons; And One or more subsequent polymerization processes, wherein the oligomeric polycarbonate is converted to a high molecular weight polycarbonate having a number average molecular weight of about 8000 to about 25000 Daltons, Method for producing polycarbonate. The method of claim 26, A process for producing a polycarbonate, wherein the mixed alkali metal salt comprises at least two alkali metal ions selected from the group consisting of cesium, sodium and potassium alkali metal salts. The method of claim 27, Wherein the salt comprises from about 0.85 to about 1.0 equivalents of cesium and from about 0.1 to about 0.6 equivalents of sodium based on the equivalent of phosphate. The method of claim 28, A method for producing a polycarbonate, wherein a mixed alkali metal salt is used in an amount of 1 × 10 ⁻⁸ to 1 × 10 ⁻³ mole per mole of dihydroxy aromatic compound. The method of claim 26, The diphenyl carbonate is used in an amount of about 0.95 to about 1.1 moles per mole of dihydroxy aromatic compound. The method of claim 26, A process for producing a polycarbonate wherein the dihydroxy aromatic compound is a bisphenol having the structure of formula (I) Formula I Where R ¹ independently of ^one another is a halogen atom, a nitro group, a cyano group, a C ₁ -C ₂₀ alkyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₆ -C ₂₀ aryl group; n and m are independently integers from 0 to 4; W is a bond, oxygen atom, sulfur atom, SO ₂ group, C ₁ -C ₂₀ aliphatic radical, C ₆ -C ₂₀ aromatic radical, C ₆ -C ₂₀ alicyclic radical or formula Wherein R ² and R ³ are independently a hydrogen atom, a C ₁ -C ₂₀ alkyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₄ -C ₂₀ aryl group; or R ² and R ³ together are one or more Form a C ₄ -C ₂₀ alicyclic ring, optionally substituted with a C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryl, C ₅ -C ₂₁ aralkyl, C ₅ -C ₂₀ cycloalkyl group, or mixtures thereof Is). The method of claim 31, wherein Bisphenol is bisphenol A; 2,2-bis (4-hydroxy-3-methylphenyl) propane; 2,2-bis (3-chloro-4-hydroxyphenyl) propane; 2,2-bis (3-bromo-4-hydroxyphenyl) propane; 2,2-bis (4-hydroxy-3-isopropylphenyl) propane; 1,1-bis (4-hydroxyphenyl) cyclohexane; 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane; And 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane. The method of claim 26, A process for preparing polycarbonate, in which the diaryl carbonate has the structure of Formula II: Formula II Where R ⁴ independently of one another is a halogen atom, a nitro group, a cyano group, a C ₁ -C ₂₀ alkyl group, a C ₁ -C ₂₀ alkoxy carbonyl group, a C ₄ -C ₂₀ cycloalkyl group or a C ₆ -C ₂₀ aryl group ego; t and v are independently integers from 0 to 5. The method of claim 33, wherein Diaryl carbonates are diphenyl carbonate, bis (4-methylphenyl) carbonate, bis (4-chlorophenyl) carbonate, bis (4-fluorophenyl) carbonate, bis (2-chlorophenyl) carbonate, bis (2,4- A method for producing a polycarbonate, wherein the polycarbonate is selected from the group consisting of difluorophenyl) carbonate, bis (4-nitrophenyl) carbonate, bis (2-nitrophenyl) carbonate and bis (methylsalicyl) carbonate. The method of claim 26, The method of making a polycarbonate, wherein the product polycarbonate contains less than about 1000 ppm price product. The method of claim 26, The diaryl carbonate is diphenyl carbonate and the dihydroxy aromatic compound is bisphenol A. Contacting diphenylcarbonate with bisphenol A in the presence of a transesterification catalyst at a temperature of about 180 to about 310 ° C. and a pressure of about 760 to about 1 torr to produce the product bisphenol A polycarbonate, Wherein the transesterification catalyst comprises one or more mixed alkali metal salts of phosphoric acid and one or more promoters comprising quaternary ammonium salts, quaternary phosphonium salts or mixtures thereof Method for producing polycarbonate. The method of claim 37, The mixed alkali metal salt comprises at least two alkali metal ions selected from the group consisting of cesium, sodium and potassium alkali metal ions. The method of claim 38, Wherein the salt comprises from about 0.85 to about 1.0 equivalents of cesium and from about 0.1 to about 0.6 equivalents of sodium based on the equivalent of phosphate. The method of claim 37, A process for producing a polycarbonate, wherein the mixed alkali metal salt comprises potassium and sodium ions. The method of claim 40, Wherein the salt comprises from about 0.85 to about 1 equivalent of potassium and from about 0.1 to about 1.0 equivalents of sodium based on the equivalent of phosphate. The method of claim 37, A method for producing a polycarbonate, wherein a mixed alkali metal salt is used in an amount of 1 × 10 ⁻⁸ to 1.0 × 10 ⁻³ mole per 1 mole of bisphenol A. The method of claim 31, wherein Contacting, Oligomerization process (first process) to prepare oligomeric polycarbonates having a number average molecular weight of about 1000 to about 7500 Daltons; And Performing a process (second process) comprising converting the oligomeric polycarbonate formed in the first process into a high molecular weight polycarbonate having a number average molecular weight of about 8000 to about 25000 daltons, Method for producing polycarbonate.