Method for preparing polysulfone (PSU) polymer

Abstract

The present invention relates to a method for preparing a polysulfone (PSU) polymer having a low yellowness index (YI). The disclosure also relates to the PSU obtained from the method, as well as to articles incorporating the PSU.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority based on U.S. Provisional Patent Application No. 62 / 937,679, filed on November 19, 2019, and European Patent Application Publication No. 20153087.0, filed on January 22, 2020, the entire contents of which are incorporated herein by reference for all purposes.

[0002] This disclosure relates to a method for preparing a polysulfone (PSU) polymer having a low yellowness index (YI). This disclosure also relates to the PSU obtained from this method, as well as articles incorporating this PSU.

Background Art

[0003] Polysulfone (PSU) polymers belong to the classification of high - performance thermoplastics and are characterized by excellent mechanical properties. PSU is commercially available, especially under the trade name UDEL® from Solvay Specialty Polymers LLC.

[0004] A PSU, and more broadly a poly(aryl ether sulfone) (PAES), can be prepared by a polycondensation reaction by a hydroxide method or a carbonate method. In the hydroxide method, a salt is formed from a dihydroxy component and a hydroxide; then, the formed diphenolate dianion then reacts with an aromatic dihalogen compound. The hydroxide method is generally not very preferred because, firstly, the stoichiometry needs to be carefully monitored, secondly, the process is a two-step synthesis, and thirdly, the use of strong bases has low tolerance to stoichiometric deviations and can adversely affect the increase in polymer molecular weight. As for the carbonate method, an aromatic dihydroxyl compound and an aromatic dihalogen compound react together in a polar aprotic solvent in the presence of a carbonate, such as sodium carbonate (Na2CO3), calcium carbonate (CaCO3), or potassium carbonate (K2CO3). According to the literature, in the carbonate method, N,N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) are generally preferred as polar aprotic solvents. Also, typically, the additional use of a solvent that forms an azeotropic mixture with water (such as toluene) is also described, whereby the water formed as a by-product during the polymerization can be continuously removed by azeotropic distillation throughout the polymerization.

[0005] Multiple patent documents describe the preparation of PAES polymers by a condensation process carried out with various solvents and apparatuses.

[0006] European Patent Application Publication No. 0412499 A1 (DEGUSSA) describes a method for forming a PAES polymer in which the dihalogen component is 4,4'-dichlorodiphenyl sulfone or 4,4'-difluorodiphenyl sulfone and the dihydroxy component includes 4,4'-isopropylidenediphenol, 4,4'-dihydroxydiphenyl sulfone, and 4,4'-dihydroxybenzophenone. The condensation is carried out in diphenyl sulfone (DPS) in the presence of sodium carbonate.

[0007] International Publication No. 01 / 66620 pamphlet (SOLVAY) describes poly(biphenyl ether sulfone) (PPSU) with improved color. The polymer is prepared by a carbonate process in a solvent mixture containing an aprotic polar solvent and a solvent that forms an azeotrope with water. The aprotic polar solvent is selected from dimethyl sulfoxide (DMSO), dimethyl sulfone, diphenyl sulfone (DPS), diethyl sulfoxide, diethyl sulfone, diisopropyl sulfone, sulfolane, tetrahydrothiophene-1-oxide, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and N-methyl-2-pyrrolidone (NMP).

[0008] Japanese Patent Application Laid-Open No. 3-294332 (Ube Industries) relates to a method for preparing a lightly colored thermoplastic sulfone polymer in which the dihalogen component is 4,4'-dichlorodiphenyl sulfone and the dihydroxy component is selected from hydroquinone, catechol, resorcinol, bis(hydroxyphenyl)alkane, dihydroxydiphenyl sulfone, 4,4'-biphenol, and dihydroxydiphenyl ether. More precisely, the examples describe the preparation of a sulfone polymer based on 4,4'-dichlorodiphenyl sulfone and 4,4'-bis(4-hydroxyphenyl)propane in 1,3-dimethyl-2-imidazolidinone (DMI) in the presence of toluene as a solvent that forms an azeotrope with water.

[0009] U.S. Patent Application Publication No. 2009 / 0275725A1 (BASF) describes a method for preparing a polysulfone having a yellowness index conforming to DIN 6167, which is carried out in a basic aprotic solvent selected from the group consisting of N-methyl-pyrrolidone (NMP), N-ethyl-pyrrolidinone (NEP), sulfolane, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), or dimethyl sulfoxide (DMSO). This invention is based on the use of special equipment, namely an active transport stirrer that passes near the wall.

[0010] U.S. Patent Application Publication No. 2012 / 029106 A1 (BASF) describes a method for producing a polybiphenyl sulfone polymer (PPSU) with a low chlorine content based on the reaction of 4,4'-dihydroxybiphenyl and 4,4'-dichlorodiphenyl sulfone. This reaction is carried out using a molar excess of the dihydroxy monomer in NMP.

[0011] Japanese Patent Application Laid-Open No. 05-86186 (Mitsui) relates to a polyether sulfone produced by polycondensing biphenol and 4,4'-dichlorodiphenyl sulfone using DMI as a polymerization solvent. This document describes, in Example 2, the preparation of a PSU polymer using strong base chemistry (KOH) in DMI and toluene. According to this, when all the components are added to the reaction mixture, the mixture is heated at a treatment temperature of 150°C for 4 hours. The amount of PSU at the end of the condensation is 26.9% by weight based on the total weight of the PSU and the solvent.

[0012] The inventors have noticed that all the preparation methods described in the literature give sulfone polymers that can be improved with respect to their molecular weight and optical properties, more precisely their yellowness index.

[0013] An object of the present invention is to provide a method for preparing a polysulfone polymer with a low yellowness index (YI) without impairing the mechanical properties. The method of the present invention is based in particular on the use of 1,3-dimethyl-2-imidazolidinone (DMI) as a solvent. SUMMARY OF THE INVENTION

[0014] One aspect of the present disclosure relates to a method for preparing a polysulfone (PSU) polymer. The applicant has found that the method of the present invention carried out in a solvent containing 1,3-dimethyl-2-imidazolidinone (DMI) enables the obtaining of a PSU having a low yellowness index (YI) that, without impairing its mechanical properties, and more surprisingly, improves its flexural strength. The PSU of the present invention advantageously also exhibits a low level of cyclic dimers. Thereby, the PSU obtained by the method of the present invention becomes very suitable for the manufacture of membranes.

[0015] The method of the present invention comprises reacting an aromatic dihydroxy monomer (a1) containing 4,4'-isopropylidenediphenol with an aromatic dihalogen sulfone monomer (a2) in a solvent which is 1,3-dimethyl-2-imidazolidinone (DMI) in the presence of one carbonate component. The method of the present invention particularly includes heating the reaction mixture (R G ) to a temperature T H and optionally maintaining this temperature for at least 20 minutes before raising the temperature of the reaction mixture (R G ) to the reaction temperature T R , wherein the temperatures T H and T R are such that 140 °C < T H < T R < 215 °C. The inventors have noticed that when the polycondensation process in DMI includes such steps, the PSU polymer advantageously exhibits a low yellowness index in addition to having the desired molecular weight (Mw) and polydispersity index (PDI). The PSU polymer obtained from this method preferably also exhibits a small amount of cyclic dimers and a small amount of residual solvent, whereby such a polymer becomes very suitable for the manufacture of, for example, hollow fibers and membranes. The PSU polymer obtained by this method has a weight average molecular weight (Mw) in the range of 70,000 g / mol to 200,000 g / mol and a polydispersity index (PDI) of less than 4 (PDI is Mw / Mn) as measured by size exclusion chromatography (SEC).

[0016] Advantageously, the method of the present invention does not require the use of a solvent that forms an azeotrope with water.

[0017] Another aspect of the present disclosure is a polysulfone (PSU) polymer obtained by the method of the present invention.

[0018] The present disclosure also relates to an article comprising the PSU of the present invention or a polymer composition comprising this PSU. The PSU polymer of the present invention is particularly well-suited for the production of porous hollow fibers and flat membranes using solvent-based processes. The PSU polymer can advantageously be used in various membrane filtration applications such as kidney dialysis, water treatment, bioprocessing, food and beverage processing, and industrial gas separation. The low-color PSU prepared according to the method of the present invention surprisingly exhibits excellent appearance. Thus, it is well-suited for applications where color, especially yellow, is not tolerated, such as in lenses, filters, and other optical products, for transparent covers and lids, and in containers, glasses, and articles where low-color transparency is desired or required. These are advantageously colorless, so the PSU polymer of the present invention can be dyed or colored to more efficiently achieve the desired color. Therefore, the polymers of the present invention can also be used in applications that are filled and colored, especially when white and light-colored articles are desired.

Embodiments for Carrying Out the Invention

[0019] An object of the present invention is to provide a method for preparing a polysulfone (PSU) polymer having a low yellowness index (YI). The method of the present invention is carried out in a solvent containing 1,3-dimethyl-2-imidazolidinone (DMI), preferably in the absence of a solvent that forms an azeotrope with water. The method of the present invention shows the advantage of being simple and inexpensive to implement. The PSU polymer prepared according to this method has a low and narrow polydispersity index (PDI) due to its narrow molecular weight distribution and can be used in many applications, especially in the production of membranes.

[0020] More precisely, the present disclosure relates to a method for preparing a polysulfone (PSU) polymer having a weight average molecular weight (Mw) of 70,000 g / mol to 200,000 g / mol and a polydispersity index (PDI) of less than 4. The method comprises - at least one aromatic dihydroxy monomer (a1) comprising 4,4'-isopropylidenediphenol; - at least one aromatic dihalogen sulfone monomer (a2) comprising at least one dihalogen compound selected from the group consisting of 4,4'-dichlorodiphenyl sulfone (DCPDS) and 4,4'-difluorodiphenyl sulfone (DFDPS), based on the total weight of the components (a2) in the reaction mixture (RG); - at least one carbonate component; - a solvent comprising 1,3-dimethyl-2-imidazolidinone (DMI); comprising a step of condensing in a reaction mixture (RG) comprising the amount of PSU at the end of the condensation is at least 30% by weight based on the total weight of PSU and DMI a solvent containing This method comprises heating the reaction mixture (R G ) to a temperature T H and optionally maintaining this temperature for at least 20 minutes before raising the temperature of the reaction mixture (R G ) to the reaction temperature T R , wherein the temperatures T H and T R are such that 140 °C < T H < T R < 215 °C.

[0021] The method of the present invention provides a high yield of PSU polymer in a limited time and can be implemented in an industrial plant. The PSU obtained from the method of the present invention not only exhibits a low yellowness index (YI), but surprisingly also exhibits good mechanical properties (in particular modulus of elasticity and flexural strength as shown in the examples). The PSU of the present invention preferably has a chlorine content bound to the polymer of less than 400 ppm (wt) based on the total weight of the PSU.

[0022] The expressions "polymer (co)" or "polymer" are used herein to designate homopolymers containing substantially 100 mol% of the same repeating units and copolymers containing at least 50 mol%, for example at least about 60 mol%, at least about 65 mol%, at least about 70 mol%, at least about 75 mol%, at least about 80 mol%, at least about 85 mol%, at least about 90 mol%, at least about 95 mol% or at least about 98 mol% of the same repeating units.

[0023] In this application, - Any description, even if described in relation to a particular embodiment, is applicable to and interchangeable with other embodiments of the present disclosure, - When an element or component is said to be included in and / or selected from a list of enumerated elements or components, in the relevant embodiments expressly contemplated herein, the element or component can be any one of the individual enumerated elements or components, or can also be selected from a group consisting of any two or more of the expressly enumerated elements or components, and it should be understood that any element or component enumerated in the list of elements or components can be omitted from such a list. - Any enumeration of numerical ranges by endpoints herein includes all numbers included within the enumerated range, as well as the endpoints and equivalents of the range.

[0024] The PSU polymer obtained by the method of the present invention is characterized by its weight average molecular weight (Mw) and its polydispersity index (referred to herein as "PDI" or "PDI index", sometimes also called the polydispersity index). Polydispersity or polydispersity corresponds to the molecular weight distribution of the various macromolecules within the polymer. The PDI index corresponds to the ratio Mw / Mn, and the number average molecular weight Mn and the weight average molecular weight Mw are determined as described above.

[0025] The PSU of the present invention is advantageously - The weight average molecular weight (Mw) is in the range of 70,000 g / mol to 200,000 g / mol, for example, 75,000 g / mol to 190,000 g / mol, or 80,000 g / mol to 180,000 g / mol, - The PDI is less than 4, for example, less than 3.8 or less than 3.6, which is characterized by.

[0026] The weight average molecular weight (Mw) of the PSU of the present invention is determined by size exclusion chromatography (SEC) using methylene chloride as the mobile phase.

[0027] In some embodiments, the polysulfone (PSU) of the present invention has the formula (L):

Chemical formula

[0028] In some preferred embodiments, R is, at each position in the above formula (L), independently a C1-C12 moiety optionally containing one or more heteroatoms; sulfonic acid and sulfonate groups; phosphonic acid and phosphonate groups; amine and quaternary ammonium groups.

[0029] In some preferred embodiments, h is zero for each R, which means that the aromatic ring is unsubstituted. In other words, according to this embodiment, the repeating unit (R PSU ) has the formula (L’): [Chemical formula] is the unit.

[0030] According to another embodiment, the repeating unit (R PSU ) is of the formula (L''): [Chemical formula] is the unit.

[0031] The PSU polymer of the present invention may thus be a homopolymer or a copolymer. When it is a copolymer, it can be a random, alternating or block copolymer.

[0032] According to one embodiment of the present invention, at least 50 mol%, at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, at least 99 mol% or all of the repeating units in the PSU are the repeating units (R PSU ) of the formula (L), (L') and / or (L'').

[0033] When the polysulfone (PSU) is a copolymer, it may be composed of repeating units (R PSU ) different from the repeating unit (R* PSU ), for example, of the formula (M), (N) and / or (O): [Chemical formula] can be composed of the repeating units.

[0034] The PSU of the present invention exhibits an Mw in the range of 70,000 g / mol to 200,000 g / mol. Such a molecular weight can be obtained by adjusting the monomer ratio of the monomers (a1):(a2). After reaching the desired Mw using an activated aromatic halide or an aliphatic halide, such as methyl chloride or benzyl chloride, etc., the condensation can be stopped.

[0035] The condensation of the present invention is carried out in a solvent containing 1,3 - dimethyl - 2 - imidazolidinone (DMI). The method of the present invention is preferably carried out in a solvent containing at least 50% by weight of DMI, at least 60% by weight of DMI, at least 70% by weight of DMI, at least 80% by weight of DMI, at least 90% by weight of DMI, or at least 95% by weight of DMI, based on the total weight of the solvent. One or more additional polar aprotic solvents can also be used. They can be selected, for example, from the group consisting of N - methyl - 2 - pyrrolidone (NMP), N,N - dimethylformamide (DMF), N,N - dimethylacetamide (DMAC), 1,3 - dimethyl - 2 - imidazolidinone, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), chlorobenzene, and sulfolane. Surprisingly, it has been found that the yellowness index of the PSU polymer obtained by the method of the present invention carried out in 1,3 - dimethyl - 2 - imidazolidinone (DMI) is lower compared to the PSU polymer obtained by the condensation process carried out in N - methyl - 2 - pyrrolidone (NMP).

[0036] The condensation of the present invention is preferably carried out in a solvent consisting essentially of 1,3 - dimethyl - 2 - imidazolidinone (DMI).

[0037] The method of the present invention is carried out in the presence of a carbonate component selected from the group of alkali metal hydrogen carbonates, such as sodium hydrogen carbonate (NaHCO3) and potassium hydrogen carbonate (KHCO3), or selected from the group of alkali metal carbonates, such as potassium carbonate (K2CO3) and sodium carbonate (Na2CO3). Preferably, the method of the present invention is carried out in the presence of potassium carbonate (K2CO3), sodium carbonate (Na2CO3), or a blend of both. According to one embodiment, the method of the present invention is carried out in the presence of a low particle size alkali metal carbonate, including anhydrous K2CO3 having a volume average particle size of less than about 100 μm, such as less than 45 μm, less than 30 μm, or less than 20 μm. According to a preferred embodiment, the method of the present invention is carried out in the presence of a carbonate component containing 50% by weight or more of K2CO3 having a volume average particle size of less than about 100 μm, such as less than 45 μm, less than 30 μm, or less than 20 μm, based on the total weight of the basic components in the reaction mixture. The volume average particle size of the carbonate used can be determined, for example, using a Malvern Mastersizer2000 for a suspension of particles in chlorobenzene / sulfolane (60 / 40).

[0038] According to one embodiment of the method of the present invention, monomer (a1) contains at least 50% by weight of 4,4'-isopropylidenediphenol (bisphenol A), such as at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, or at least 95% by weight of 4,4'-isopropylidenediphenol, based on the total weight of monomer (a1). Preferably, monomer (a1) consists essentially of 4,4'-isopropylidenediphenol (bisphenol A).

[0039] According to another embodiment of the method of the present invention, monomer (a2) is a 4,4'-dihalosulfone containing at least one of 4,4'-dichlorodiphenyl sulfone (DCDPS) or 4,4'-difluorodiphenyl sulfone (DFDPS), preferably containing 4,4'-dichlorodiphenyl sulfone (DCDPS).

[0040] According to yet another embodiment of the method of the present invention, monomer (a2) comprises at least 50% by weight of 4,4'-dichlorodiphenyl sulfone (DCDPS), for example at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, or at least 95% by weight of DCDPS, based on the total weight of monomer (a2).

[0041] According to the condensation of the present invention, the components of the reaction mixture generally react simultaneously. While the temperature of the reaction mixture (R G ) is adjusted along the process, the reaction is carried out without isolating the intermediate product.

[0042] The molar ratio of component (a1):(a2) can be 0.9 to 1.2, for example 0.92 to 1.15 or 0.95 to 1.1.

[0043] The molar ratio of component (a1):(a2) is preferably 1.005 to 1.2, or 1.009 to 1.15. Using an excess of component (a1) is preferred because it contributes to reducing the chlorine content bound to the polymer, especially at high conversion rates. In a particularly preferred embodiment, the molar ratio of component (a1):(a2) is 1.01 to 1.08, especially 1.01 to 1.05, very preferably 1.015 to 1.04. Thereby, the molecular weight can be controlled particularly effectively.

[0044] The molar ratio of carbonate component: dihydroxy monomer (a1) can be 1.0 to 1.2, for example 1.01 to 1.15, or 1.02 to 1.1. The molar ratio of carbonate component: dihydroxy monomer (a1) is preferably 1.05 or more, for example 1.06 or 1.08.

[0045] The method of the present invention comprises heating the reaction mixture (R G ) to temperature T H and optionally maintaining this temperature for at least 20 minutes before raising the temperature of the reaction mixture (R G ) to the reaction temperature T R . Temperature T H is the reaction temperature TR is lower. More precisely, the temperature T R and T H are temperatures such that the following inequality is satisfied: 140 °C < T H < T R < 215 °C.

[0046] According to one embodiment, the step of raising the temperature from T H to T R is carried out, for example, stepwise or continuously over a time varying from 5 minutes to 5 hours. Here, the term "stepwise" (or "sequentially") means in sequence, for example a series of sequential temperature increases (e.g., 2 °C / min or 5 °C every 5 minutes), with an interruption between each temperature increase. The term "continuously" means gradually in the direction of reaching the reaction temperature T R (e.g., 1 °C per minute until the reaction mixture reaches T R ).

[0047] According to one embodiment, the step of raising the temperature from T H to T R is carried out over a time of 1 hour ± 10 minutes from a temperature T H of 140 °C ± 5 °C to a temperature T R of 195 °C ± 5 °C.

[0048] In some embodiments, the reaction mixture (R G ) is maintained at the temperature T H for at least 30 minutes, for example at least 40 minutes, at least 50 minutes, or for 1 hour or more. The reaction mixture (R G ) can be maintained at the temperature T H for less than 4 hours, preferably less than 3 hours.

[0049] The temperature T H is lower than the reaction temperature T R . Preferably, the temperature T H is at least 5 °C lower than the reaction temperature T R , such that the following inequality T H < T RSatisfies -5°C. More preferably, the temperature T H is at least 10°C lower than the reaction temperature, and as a result, the following inequality T H < T R is satisfied. More preferably, the temperature T H is at least 15°C lower than the reaction temperature, and as a result, the following inequality T H < T R is satisfied.

[0050] According to the present invention, the reaction temperature T R is less than 215°C. Preferably, the temperature T R is less than 210°C. More preferably, T R is less than 208°C. Even more preferably, the temperature T R is less than 205°C.

[0051] The temperature T H is greater than 140°C. Preferably, the temperature T H is greater than 145°C. More preferably, the temperature T H is greater than 150°C. Even more preferably, the temperature T H is greater than 155°C.

[0052] In some embodiments, the temperature T H is included in the range of 140 to 190°C, such as 145 to 185°C, 150 to 180°C, or 155 to 175°C.

[0053] According to a preferred embodiment, the reaction temperature (R G ) is maintained at a temperature T H of 170°C ± 5°C for a time of 1 hour ± 10 minutes.

[0054] In some embodiments, the temperature T R is included in the range of 180 to 215°C, such as 185 to 210°C, 188 to 208°C, 190 to 205°C.

[0055] According to a preferred embodiment, the reaction mixture (R G ) is the reaction mixture (R GThe temperature of R is maintained at a temperature T of 170°C ± 5°C for 1 hour ± 10 minutes before raising it to 195°C ± 5°C for at least 1 hour up to a certain reaction temperature T H .

[0056] In a preferred embodiment, the inequality (1) or (1): · 140°C < T H < 190°C (1), and / or · 180°C < T R < 215°C (2) (However, when both inequalities (1) and (2) are satisfied, provided that T H < T R ) At least one of them satisfies the following.

[0057] In another preferred embodiment, the inequality (3) or (4): · 150°C < T H < 190°C (3), and / or · 180°C < T R < 210°C (4) (However, when both inequalities (3) and (4) are satisfied, provided that T H < T R ) At least one of them satisfies the following.

[0058] In some embodiments, the reaction time is in the range of 1 to 10 hours, preferably less than 9 hours, and even more preferably less than 8 hours.

[0059] According to the present invention, the carbonate component can be added to the reaction mixture all at once at the start of the reaction, for example, or added over a certain period of time during the polycondensation reaction. This certain period of time may be in the range of 5 minutes to 5 hours, preferably 10 minutes to 2 hours, and more preferably less than 1 hour. According to one embodiment, the carbonate component is added to the reaction mixture (R G ) over a period of 30 minutes ± 5 minutes.

[0060] According to the present invention, when the carbonate component is added to the reaction mixture (R G ), it can be added sequentially or continuously to the reaction mixture (R G ). In the context of this method, the term "sequentially" means successive, for example a series of sequential additions (at least two additions) to the reaction vessel with interruptions between the additions, and the term "continuously" means that it is carried out gradually towards the conversion of the reactants contained in the reaction mixture. One continuous supply of the components in the reaction vessel can be, for example, by dropping.

[0061] In some embodiments, after reaching the desired molecular weight, an alkyl chloride, preferably methyl chloride, is added to the reaction mixture (R G ).

[0062] In some embodiments, the reaction conditions are selected such that the conversion rate (C) is at least 90%, particularly at least 95%, particularly preferably at least 98%. In the context of the present invention, the conversion rate (C) is the molar ratio of the reacted reactive groups (i.e., hydroxy groups and chloro groups).

[0063] According to one embodiment, the method of the present invention is carried out in the absence of a solvent that forms an azeotrope with water. According to a preferred embodiment, the method of the present invention is carried out in a solvent that at least partially contains DMI as an aprotic polar solvent and is used in the absence of a solvent that forms an azeotrope with water. Solvents that form an azeotrope with water include, in particular, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, chlorobenzene. All of these azeotroping agents are classified as hazardous air pollutants in the United States. In some preferred methods, the reaction mixture (R G(a) does not contain any substance that forms an azeotrope with water. Although the prior art methods are described as requiring the use of an azeotropic agent during polycondensation, surprisingly, in the process of the present invention, it has been found that the use of such a solvent that forms an azeotrope with water is unnecessary for removing the water formed from the reaction of component (a1) and component (a2) from the reactor. This makes the process of the present invention simpler and more cost-effective, resulting in a polymer with an overall low solvent content, which is most useful in many applications, especially in membrane manufacturing. Also, the actual operation of manufacturing the polymer without using an azeotropic solvent is much simpler, efficient, and cost-effective because it does not require a secondary operation for recovering and reusing the azeotropic solvent. According to this embodiment, the amount of the solvent that forms an azeotrope with water is preferably less than 1% by weight, more preferably less than 0.5% by weight, still more preferably less than 0.1% by weight, based on the total weight of the solvent in the reaction mixture.

[0064] Inorganic components, such as sodium chloride or potassium chloride or excess base, can be removed by appropriate methods such as dissolution and filtration, sieving, or extraction, before or after the isolation of PSU.

[0065] According to the present invention, the amount of PSU at the end of condensation is at least 30% by weight, for example at least 35% by weight, at least 37% by weight, at least 40% by weight, at least 45% by weight, or at least 50% by weight, based on the total weight of PSU and the solvent.

[0066] At the end of the reaction, the PSU polymer can be separated from other components (salts, bases, …) to obtain a PSU solution. For example, filtration can be used to separate the PSU polymer from other insoluble components.

[0067] The PSU polymer obtained from such a process advantageously exhibits a low level of cyclic dimers or cyclic oligomers. The cyclic dimers and oligomers have the formula (C):

Chemical formula

[0068] According to one embodiment of the present invention, the PSU contains less than 1.15% by weight of, for example, cyclic oligomers and cyclic dimers according to formula (C). For example, the PSU contains less than 1.13% by weight, less than 1.10% by weight, less than 1.05% by weight, and even less than 1.0% by weight of cyclic oligomers and cyclic dimers based on the total weight of the PSU polymer.

[0069] When analyzed by size exclusion chromatography (SEC), after elution of the PSU and, if present, before elution of the polymerization reaction solvent, the oligomers elute as two main decomposition components, so that the oligomer content in the reaction mixture can be evaluated. SEC chromatography can be carried out using methylene chloride as the eluent and a P1 gel 5μm mixed-D, 300×7.5mm column available from Polymer laboratories.

[0070] According to one embodiment, the method of the present invention can not only obtain a PSU with a specific Mw and PDI, but also the PSU thus obtained contains less than 1% by weight of oligomers having a molecular weight of less than 4,000 g / mol, for example, less than 0.9% by weight, less than 0.8% by weight, less than 0.7% by weight, and even less than 0.5% by weight of oligomers having a molecular weight of less than 4,000 g / mol, less than 3,000 g / mol, or less than 2,000 g / mol based on the total weight of the PSU polymer.

[0071] According to another embodiment, the method of the present invention also enables obtaining a PSU having the following: - Measured using a TA Instruments ARES G2 rheometer (at 380 °C, 1.6 mm gap, using a frequency of 10.0 rad / s at 5.0% strain for oscillatory time sweep analysis) with a 25 mm disk, the VR40 melt stability, which is less than 1.0, for example less than 0.99 or less than 0.98, measured as the ratio of the viscosity at 40 minutes to the viscosity at 10 minutes - Flexural strength of at least 110.0 MPa, at least 110.2 MPa, at least 110.5 MPa, or at least 110.8 MPa, measured according to ASTM method D790 (with six specimens at 2 mm / min, room temperature, 50.8 mm span or gauge, 5 mm load radius), and / or - Modulus of elasticity of at least 2.50 GPa, for example at least 2.55 GPa, at least 2.60 GPa, or at least 2.65 GPa, measured according to ASTM 638.

[0072] PSU polymers, compositions, and articles The present invention also relates to PSU having a weight average molecular weight (Mw) of 70,000 g / mol to 200,000 g / mol and a polydispersity index (PDI) of less than 4.

[0073] According to one embodiment, this PSU is obtained from the above-described preparation method, particularly in a solvent containing 1,3-dimethyl-2-imidazolidinone (DMI).

[0074] In some embodiments, the PSU may have a DMI content of less than 300 ppm (wt), for example less than 200 ppm (wt) of DMI, less than 100 ppm (wt), less than 50 ppm (wt) of DMI, or less than 10 ppm (wt) of DMI, based on the total weight of the PSU.

[0075] In some other embodiments, the PSU may have a DMI content of from 1 ppm (wt) to less than 300 ppm (wt), for example 1 to 200 ppm (wt) of DMI, 1 to 100 ppm (wt), 1 to 50 ppm (wt) of DMI, or 1 to 10 ppm (wt) of DMI, based on the total weight of the PSU.

[0076] In some embodiments, the PSU of the present invention has a yellowness index (YI) of less than 6.0, such as YI of 5.9 or less, measured in accordance with ASTM E313 using an x-rite Color i7 spectrophotometer.

[0077] In some embodiments, the PSU of the present invention preferably has a chlorine content bonded to the polymer of less than 400 ppm (wt), such as less than 300 ppm (wt), less than 200 ppm (wt), less than 100 ppm (wt), less than 50 ppm (wt), and even less than 20 ppm (wt), based on the total weight of the PSU.

[0078] In some other embodiments, the PSU of the present invention has a chlorine content bonded to the polymer of at least 1 ppm (wt), such as chlorine bonded to the polymer of 1 - 300 ppm (wt), chlorine bonded to the polymer of 1 - 200 ppm (wt), chlorine bonded to the polymer of 1 - 100 ppm (wt), chlorine bonded to the polymer of 1 - 50 ppm (wt), or chlorine bonded to the polymer of 1 - 10 ppm (wt), based on the total weight of the PSU.

[0079] Such advantageous features can be obtained by the above process, the use of DMI, the preferred absence of solvents forming an azeotrope with water, and the minimum concentration of reactive substances in the reaction mixture during condensation (evaluated by the minimum concentration in the reaction mixture (RG) at the end of the reaction).

[0080] According to another embodiment, the PSU of the present invention exhibits at least one of the following characteristics: - VR40 melt stability of less than 1.0, such as less than 0.99 or less than 0.98, measured as the ratio of the viscosity at 40 minutes to the viscosity at 10 minutes using a 25 mm disk with a TA Instruments ARES G2 rheometer (at 380 °C, 1.6 mm gap, using a frequency of 10.0 rad / s at 5.0% strain in oscillatory time sweep analysis). - Flexural strength of at least 110.0 MPa, at least 110.2 MPa, at least 110.5 MPa, or at least 110.8 MPa, measured in accordance with ASTM method D790 (2 mm / min, room temperature, 50.8 mm span or gauge, 5 mm load radius) for six specimens, and / or - Modulus of elasticity of at least 2.50 GPa, such as at least 2.55 GPa, at least 2.60 GPa, or at least 2.65 GPa, measured in accordance with ASTM 638.

[0081] The present invention also relates to a thermoplastic composition (C) comprising the PSU of the present invention described above, and an article comprising a polymer composition (C) comprising at least the PSU of the present invention. Such compositions can be used in the manufacture of molded articles, fibers, films, membranes, or foams. The present invention also relates to a molded article, fiber, film, membrane, or foam comprising the thermoplastic composition (C) or PSU polymer of the present invention.

[0082] The thermoplastic composition (C) may contain PSU in an amount of at least 1% by weight, such as at least 5% by weight, at least 10% by weight, at least 15% by weight, at least 20% by weight, at least 25% by weight, or at least 30% by weight, based on the total weight of the thermoplastic composition (C).

[0083] The thermoplastic composition (C) may contain PSU in an amount of more than 50% by weight, such as more than 55% by weight, more than 60% by weight, more than 65% by weight, more than 70% by weight, more than 75% by weight, more than 80% by weight, more than 85% by weight, more than 90% by weight, more than 95% by weight, or more than 99% by weight, based on the total weight of the thermoplastic composition (C).

[0084] According to one embodiment, the thermoplastic composition (C) contains PSU in an amount in the range of 1 to 99% by weight, such as 3 to 96% by weight, 6 to 92% by weight, or 12 to 88% by weight, based on the total weight of the thermoplastic composition (C).

[0085] The thermoplastic composition (C) may optionally further comprise one or more additional additives selected from the group consisting of an ultraviolet light stabilizer, a heat stabilizer, an acid scavenger (i.e., zinc oxide, magnesium oxide), an antioxidant, a pigment, a processing aid, a lubricant, a flame retardant, and / or a conductive additive (i.e., carbon black and carbon nanofibers).

[0086] The thermoplastic composition (C) may further comprise a polymer other than PSU, such as another sulfone polymer, such as poly(biphenyl ether sulfone) (PPSU), polyether sulfone (PES), or polyphenylene sulfide (PPS), poly(aryl ether ketone) (PAEK), such as poly(ether ether ketone) (PEEK), poly(ether ketone ketone) (PEKK), poly(ether ketone) (PEK) or a copolymer of PEEK and poly(diphenyl ether ketone) (PEEK-PEDEK copolymer), polyetherimide (PEI), and / or polycarbonate (PC).

[0087] The thermoplastic composition (C) may further comprise a flame retardant, such as a halogen and a halogen-free flame retardant.

[0088] The thermoplastic composition (C) may include glass fibers, such as E-glass fibers or high modulus glass fibers having a modulus of elasticity (also referred to as tensile modulus of elasticity) of at least 76, preferably at least 78, more preferably at least 80, and most preferably at least 82 GPa as measured according to ASTM D2343. The polymer composition (C) may also include high modulus glass fibers selected from the group consisting of R, S, and T glass fibers, and may be included in an amount of, for example, at least 5 wt%, such as at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, at least 26 wt%, or at least 28 wt% based on the total weight of the thermoplastic composition (C). The thermoplastic composition (C) may include circular cross-section glass fibers and / or non-circular cross-section glass fibers (e.g., flat, rectangular, cocoon-shaped glass fibers).

[0089] The thermoplastic composition (C) can be produced by methods well known to those skilled in the art. For example, such methods include, but are not limited to, melt mixing processes. The melt mixing process is typically carried out by heating the polymer components above the melting temperature of the thermoplastic polymer, thereby forming a melt of the thermoplastic polymer. In some embodiments, the processing temperature ranges from about 280 to 450 °C, preferably from about 290 to 400 °C, from about 300 to 360 °C or from about 310 to 340 °C. Suitable melt mixing devices are, for example, kneaders, Bradbury mixers, single-screw extruders, and twin-screw extruders. Preferably, an extruder equipped with means for introducing all of the desired components either into the feed port of the extruder or into the melt is used. The components of the polymer composition are fed to the melt mixing device and melt mixed therein. The components may be fed simultaneously as a powder mixture or granule mixer, also known as a dry blend, or separately.

[0090] The order in which the components are combined during melt mixing is not particularly limited. In one embodiment, the components can be mixed in a single batch such that all of the desired amounts of each component are added together and subsequently mixed. In other embodiments, an initial subset of components can be mixed together first, and one or more remaining components can be added to the mixture for further mixing. For the sake of clarity, all of the desired amounts of each component do not have to be mixed as a single amount. For example, for one or more components, partial amounts can be added and mixed first, and then some or all of the remainder can be added and mixed.

[0091] The thermoplastic polymer composition (C) may be suitable for the production of articles useful in a variety of applications. For example, the PSU polymers of the present invention are well-suited for the production of porous hollow fibers and flat membranes using solvent-based processes. They can be used in a variety of membrane filtration applications such as kidney dialysis, water treatment, bioprocessing, food and beverage processing, and industrial gas separation. The low-color PSU prepared according to the method of the present invention has an excellent appearance and is suitable, for example, for use in applications where color, especially yellow, is not tolerated, such as in lenses, filters, and other optical products, for transparent covers and lids, and in containers, glasses, and articles where low-color transparency is desired or required. Since the improved resins of the present invention do not have the yellow or beige appearance of prior art resins, they can also be more easily dyed or colored to achieve the desired color. Thus, the resins of the present invention may also be useful in filled and colored applications, especially when white and light-colored articles are desired.

[0092] In some embodiments, the molded article can be produced from the polymer composition using any suitable melt processing method such as injection molding, extrusion molding, rotational molding, or blow molding.

[0093] To the extent that the disclosure of any patent, patent application, and publication incorporated herein by reference might render the terms of this application unclear, this description shall control.

[0094] Here, exemplary embodiments will be described in the following non-limiting examples.

Examples

[0095] The present disclosure will now be described in more detail in connection with the following examples, which are for illustrative purposes only and are not intended to limit the scope of the present disclosure.

[0096] Starting materials 4,4'-Isopropylidenediphenol (bisphenol A) polycarbonate grade (purity > 99.5%) 4,4'-Dichlorodiphenylsulfone (DCPDS) purity > 99.7% Potassium carbonate (K2CO3), d 90 <45 μm, commercially available from Sigma Aldrich N-Methyl-2-pyrrolidone (NMP), commercially available from Sigma Aldrich (purity ≥ 99.0%) 1,3-Dimethyl-2-imidazolidinone (DMI), commercially available from TCI America (purity > 99%) Methyl chloride (MeCl), commercially available from Matheson, (purity 99.9%) Oxalic acid dihydrate (COOH)2·2H2O, commercially available from SigmaAldrich Methanol (purity 100%), commercially available from Brenntag Toluene, commercially available from Fisher Chemical (purity ≥ 99.5%)

[0097] The following polymers were prepared: PSU#1 (comparison), polysulfone (PSU) having an Mw of 85,035 g / mol and a PDI of 3.19 was prepared in NMP according to the following process:

[0098] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean-stark trap with a reflux condenser, 103.1740 g (0.4519 mol) of bisphenol A, 129.7799 g (0.4519 mol) of DCPDS, 65.5861 g (0.4745 mol) of K2CO3, and 200.00 g of NMP were added. Stirring and a nitrogen flow were established, and after purging the reaction mixture with nitrogen for 30 minutes, heating was initiated with an external oil bath at a target internal temperature of 195 °C. Water, a byproduct of the polymerization reaction, was continuously distilled off from the reactor and collected in the dean-stark trap. After reaching 195 °C, the reaction was held at that temperature until the desired Mw was reached. After reaching the desired molecular weight, polymerization was terminated by sparging gaseous MeCl through the reaction mixture at a rate of 1 g / min over 30 minutes. The reaction mixture was diluted with 600 g of NMP containing 1.27 g of oxalic acid dihydrate. The diluted polymer solution was filtered under pressure through a 2.7 μm glass fiber filter pad to remove salts. The polymer solution was precipitated in methanol at a polymer to non-solvent ratio of 1:30 to obtain a white solid. The isolated white solid was then washed 6 times with methanol, vacuum filtered, and dried in a vacuum baking oven at 120 °C for 24 hours. Molecular weight and its distribution were measured by SEC. The results are shown in Table 1.

[0099] PSU#2 (comparative), a polysulfone (PSU) having an Mw of 66,562 g / mol and a PDI of 2.76, was prepared according to exactly the same process as in Example 1, except that the condensation was carried out in DMI instead of NMP:

[0100] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser were placed 159.80 g (0.70 mol) of bisphenol A, 201.01 g (0.70 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, and 309.77 g of DMI. Stirring and a nitrogen flow were established, and after purging the reaction mixture with nitrogen for 30 minutes, heating was started with an external oil bath at a target internal temperature of 190 °C. Water, a byproduct of the polymerization reaction, was continuously distilled off from the reactor and collected in the Dean-Stark trap. After reaching 195 °C, the reaction was held at that temperature until the desired Mw was reached. After reaching the desired molecular weight, the polymerization was stopped by sparging gaseous MeCl through the reaction mixture at a rate of 1 g / min over 30 minutes. The reaction mixture was diluted with 1,351 g of DMI. The diluted polymer solution was filtered under pressure through a 2.7 μm glass fiber filter pad to remove salts. The polymer solution was precipitated in methanol at a polymer to non-solvent ratio of 1:30 to obtain a white solid. The isolated white solid was then washed six times with methanol, vacuum filtered, and dried in a vacuum baking oven at 120 °C for 24 hours. The molecular weight and its distribution were measured by SEC. The results are shown in Table 1.

[0101] PSU #3 (comparative): A polysulfone (PSU) having an Mw of 153,966 g / mol and a PDI of 6.76 was prepared according to the process outlined in JP-A-3-294332 A2 (UBE).

[0102] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser, 79.90 g (0.35 mol) of bisphenol A, 100.51 g (0.35 mol) of DCPDS, 53.21 g (0.385 mol) of K2CO3, 441.01 g of DMI, and 24.28 g of toluene were added. Stirring and the flow of nitrogen were established, and after purging the reaction mixture with nitrogen for 15 minutes, heating was initiated with an external oil bath at a target internal temperature of 190 °C. Water, a byproduct of the polymerization reaction, was continuously distilled off from the reactor and collected in the Dean-Stark trap. After reaching 190 °C, the reaction was held at that temperature for 5 hours. The reaction mixture was cooled to 130 °C, and methyl chloride was sparged through the reaction mixture at a rate of 1 g / min for 30 minutes. The reaction mixture was diluted with 440 g of DMI. The diluted polymer solution was filtered under pressure through a 2.7 μm glass fiber filter pad to remove salts. The polymer solution was precipitated in methanol at a polymer to non-solvent ratio of 1:30 to obtain a white solid. Subsequently, the isolated white solid was washed 6 times with methanol, vacuum filtered, and dried in a vacuum baking oven at 120 °C for 24 hours. The molecular weight and its distribution were measured by SEC. The results are shown in Table 1.

[0103] PSU #4 (comparative): A polysulfone (PSU) having an Mw of 84,013 g / mol and a PDI of 3.12 was prepared in NMP according to Example 1, except that the condensation was carried out at different temperature settings.

[0104] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser were placed 103.1740 g (0.4519 mol) of bisphenol A, 129.7799 g (0.4519 mol) of DCPDS, 65.5861 g (0.4745 mol) of K2CO3, and 200.00 g of NMP. Stirring and the nitrogen flow were established, and after purging the reaction mixture with nitrogen for 30 minutes, heating was started with an external oil bath at a target internal temperature of 170 °C. Water, a by-product of the polymerization reaction, was continuously distilled off from the reactor and collected in the Dean-Stark trap. After reaching 170 °C, the reaction was held at that temperature for 1 hour and then raised to 195 °C. After reaching 195 °C, the reaction was held at that temperature until the desired Mw was reached. After reaching the desired molecular weight, polymerization was terminated by sparging gaseous MeCl through the reaction mixture at a rate of 1 g / min over 30 minutes. The reaction mixture was diluted with 600 g of NMP. The diluted polymer solution was filtered under pressure through a 2.7 μm glass fiber filter pad to remove salts. The polymer solution was precipitated in methanol at a polymer to non-solvent ratio of 1:30 to obtain a white solid. The isolated white solid was then washed 6 times with methanol, vacuum filtered, and dried in a vacuum baking oven at 120 °C for 24 hours. The molecular weight and its distribution were measured by SEC. The results are shown in Table 1.

[0105] PSU #5 (the present invention): Polysulfone (PSU) having an Mw of 71,082 g / mol and a PDI of 3.64 was prepared in DMI as follows:

[0106] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean-stark trap with a reflux condenser, 103.1740 g (0.4519 mol) of bisphenol A, 129.7799 g (0.4519 mol) of DCPDS, 65.5861 g (0.4745 mol) of K2CO3, and 270.59 g of DMI were added. Stirring and the nitrogen flow were established, and after purging the reaction mixture with nitrogen for 30 minutes, heating was started with an external oil bath at a target internal temperature of 195 °C. Water, a byproduct of the polymerization reaction, was continuously distilled off from the reactor and collected in the dean-stark trap. After reaching 195 °C, the reaction was held at that temperature until the desired Mw was reached. After reaching the desired molecular weight, polymerization was stopped by sparging gaseous MeCl through the reaction mixture at a rate of 1 g / min over 30 minutes. The reaction mixture was diluted with 529.41 g of DMI. The diluted polymer solution was filtered under pressure through a 2.7 μm glass fiber filter pad to remove salts. The polymer solution was precipitated in methanol at a polymer to non-solvent ratio of 1:30 to obtain a white solid. The isolated white solid was then washed 6 times with methanol, vacuum filtered, and dried in a vacuum baking oven at 120 °C for 24 hours. Molecular weight and its distribution were measured by SEC. Yield: >90%. The results are shown in Table 1.

[0107] PSU#6 (the present invention): A polysulfone (PSU) having an Mw of 86,687 g / mol and a PDI of 3.27 was prepared in DMI as follows:

[0108] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean-stark trap with a reflux condenser, 103.1740 g (0.4519 mol) of bisphenol A, 129.7799 g (0.4519 mol) of DCPDS, and 200.00 g of DMI were added. Stirring and a nitrogen flow were established, and after purging the reaction mixture with nitrogen for 30 minutes, heating was started with an external oil bath at a target internal temperature of 170 °C. Water, a byproduct of the polymerization reaction, was continuously distilled off from the reactor and collected in the dean-stark trap. After reaching 150 °C, 65.5861 g (0.4745 mol) of K2CO3 was added in four portions over 30 minutes. After reaching 170 °C, the reaction was held at that temperature for 1 hour and then raised to 195 °C. After reaching 195 °C, the reaction was held at that temperature until the desired Mw was reached. After reaching the desired molecular weight, polymerization was terminated by sparging gaseous MeCl through the reaction mixture at a rate of 1 g / min over 30 minutes. The reaction mixture was diluted with 600 g of DMI. The diluted polymer solution was filtered under pressure through a 2.7 μm glass fiber filter pad to remove salts. The polymer solution was precipitated in methanol at a polymer to non-solvent ratio of 1:30 to obtain a white solid. The isolated white solid was then washed six times with methanol, vacuum filtered, and dried in a vacuum baking oven at 120 °C for 24 hours. Molecular weight and its distribution were measured by SEC. Yield: >90%. The results are shown in Table 1.

[0109] PSU #7 (present invention): A polysulfone (PSU) having an Mw of 84,069 g / mol and a PDI of 3.46 was prepared in DMI as follows:

[0110] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, and 309.77 g of DMI were placed. Stirring and the flow of nitrogen were established, and after purging the reaction mixture with nitrogen for 30 minutes, heating was started with an external oil bath at a target internal temperature of 170 °C. Water, a byproduct of the polymerization reaction, was continuously distilled off from the reactor and collected in the Dean-Stark trap. After reaching 170 °C, the reaction was held at that temperature for 1 hour and then raised to 195 °C. After reaching 195 °C, the reaction was held at temperature T until an Mw of at least 75,000 g / mol was reached. R After reaching the desired molecular weight, the polymerization was terminated by sparging gaseous MeCl through the reaction mixture at a rate of 1 g / min over 30 minutes. The reaction mixture was diluted with 404.0 g of DMI. The diluted polymer solution was filtered under pressure through a 2.7 μm glass fiber filter pad to remove salts. The polymer solution was precipitated in methanol at a polymer to non-solvent ratio of 1:30 to obtain a white solid. The isolated white solid was then washed 6 times with methanol, vacuum filtered, and dried in a vacuum baking oven at 120 °C for 24 hours. Molecular weight and its distribution were measured by SEC. Yield: >90%. The results are shown in Table 2.

[0111] Polysulfone (PSU) having an Mw of 79,028 g / mol and a PDI of 3.42, PSU#8 (the present invention), was prepared in DMI according to the following process:

[0112] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, and 309.77 g of DMI were placed. The remaining process was carried out at reaction temperature T RIt was the same as PSU#8 except that it was 200 °C. The results are shown in Table 2.

[0113] PSU#9 (the present invention): Polysulfone (PSU) having an Mw of 80,555 g / mol and a PDI of 3.53 was prepared in DMI according to the following process:

[0114] 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, and 309.77 g of DMI were placed in a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean - stark trap with a reflux condenser. The remaining process was that the reaction temperature T R It was the same as PSU#8 except that it was 205 °C. The results are shown in Table 2.

[0115] PSU#10 (the present invention): Polysulfone (PSU) having an Mw of 73,626 g / mol and a PDI of 3.48 was prepared in DMI according to the following process:

[0116] 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, and 309.77 g of DMI were placed in a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean - stark trap with a reflux condenser. The remaining process was that the reaction temperature T R It was the same as PSU#8 except that it was 210 °C. The results are shown in Table 2.

[0117] PSU#11 (the present invention): Polysulfone (PSU) having an Mw of 79,328 g / mol and a PDI of 3.55 was prepared in DMI according to the following process:

[0118] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, and 309.77 g of DMI were placed. The remaining process was the same as PSU#8 except that the reaction temperature T R was 190 °C. The results are shown in Table 2.

[0119] PSU#12 (the present invention): Polysulfone (PSU) having an Mw of 85,368 g / mol and a PDI of 3.56 was prepared in DMI according to the following process:

[0120] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, and 309.77 g of DMI were placed. The remaining process was the same as PSU#8 except that the temperature T H was maintained at 170 °C for 3 hours. The results are shown in Table 2.

[0121] PSU#13 (the present invention): Polysulfone (PSU) having an Mw of 85,368 g / mol and a PDI of 3.56 was prepared in DMI according to the following process:

[0122] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 103.52 g (0.749 mol) of K2CO3, and 309.77 g of DMI were placed. The remaining process was the same as PSU#8 except that the reaction temperature T H was 150 °C. The results are shown in Table 3.

[0123] PSU #14 (The present invention): Polysulfone (PSU) having an Mw of 88,377 g / mol and a PDI of 3.60 was prepared in DMI according to the following process:

[0124] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean-stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 103.52 g (0.749 mol) of K2CO3, and 309.77 g of DMI were added. The remaining process was the same as PSU #8 except that the reaction temperature T H was 180 °C. The results are shown in Table 3.

[0125] PSU #15 (The present invention): Polysulfone (PSU) having an Mw of 86,243 g / mol and a PDI of 3.55 was prepared in DMI according to the following process:

[0126] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean-stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 103.52 g (0.749 mol) of K2CO3, and 309.77 g of DMI were added. The remaining process was the same as PSU #8 except that the reaction temperature T H was 160 °C. The results are shown in Table 3.

[0127] PSU #16 (Comparative): Polysulfone (PSU) having an Mw of 59,849 g / mol and a PDI of 3.12 was prepared in DMI as follows:

[0128] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, 309.77 g of DMI, and 102.60 g of MCB were added. Stirring and the nitrogen flow were established, and after purging the reaction mixture with nitrogen for 30 minutes, heating was initiated with an external oil bath at a target internal temperature of 195 °C. Water, a byproduct of the polymerization reaction, was continuously distilled off from the reactor and collected in the Dean-Stark trap. After reaching 195 °C, the reaction was held at that temperature until the desired Mw was reached. After reaching the desired molecular weight, polymerization was terminated by sparging gaseous MeCl through the reaction mixture at a rate of 1 g / min over 30 minutes. The reaction mixture was diluted with 343 g of DMI. The diluted polymer solution was filtered under pressure through a 2.7 μm glass fiber filter pad to remove salts. The polymer solution was precipitated in methanol at a polymer to non-solvent ratio of 1:30 to obtain a white solid. The isolated white solid was then washed 6 times with methanol, vacuum filtered, and dried in a vacuum baking oven at 120 °C for 24 hours. Molecular weight and its distribution were measured by SEC. Yield: >90%. The results are shown in Table 3.

[0129] PSU#17 (comparative): A polysulfone (PSU) having an Mw of 62,876 g / mol and a PDI of 3.19 was prepared in DMI as follows:

[0130] Into a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a Dean-Stark trap with a reflux condenser, 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 106.42 g (0.770 mol) of K2CO3, and 309.77 g of DMI were added. The remaining process was the same as PSU#16 except that the reaction temperature T R was 200 °C. The results are shown in Table 3.

[0131] PSU #18 (comparison): Polysulfone (PSU) having an Mw of 6,997 g / mol and a PDI of 6.01 was prepared in DMI as follows:

[0132] 159.80 g (0.700 mol) of bisphenol A, 201.01 g (0.700 mol) of DCPDS, 101.58 g (0.735 mol) of K2CO3, and 309.77 g of DMI were placed in a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean-stark trap with a reflux condenser. The remaining process was the same as that of PSU #16 except that the reaction temperature T R was 175 °C. The results are shown in Table 3.

[0133] PSU #19 (Comparison): An attempt to prepare polysulfone (PSU) according to the process outlined in JP-A-05-86186 (Mitsui) using a strong base chemistry (aqKOH) containing an azeotropic mixture (toluene): In a 1 L resin flask equipped with an overhead stirrer, a nitrogen dip tube, and a dean-stark trap with a reflux condenser, 57.07 g (0.250 mol) of bisphenol A, 300.75 g of DMI, 125 ml of toluene, and 70.132 g (0.500 mol) of 40% aqueous potassium hydroxide solution were placed. A flow of nitrogen gas was established through the dip tube. The mixture was heated to 130 °C under a constant flow of nitrogen. Azeotropic dehydration was carried out at 130 °C for 4 hours while returning toluene to the reactor. After 4 hours of dehydration, a solution of 71.790 g (0.250 mol) of DCDPS in 50 g of toluene was added to the reactor using a dropping funnel. While removing toluene, the contents of the reactor were heated to 150 °C. Polymerization was carried out at 150 °C for 4 hours. At the end of the polymerization time, a slightly viscous, pale yellow solution was obtained. The contents of the reactor were cooled to room temperature and removed into 1250 g of methanol being rapidly stirred using a Waring blender. The polymer powder was filtered and placed in a beaker containing 1250 g of water and stirred. 1N HCl was slowly added to adjust the pH to 3 - 4. The polymer powder was isolated by filtration. The polymer powder was washed twice with a Waring blender using 1250 g of DI water each time. After the final wash with 1250 g of methanol, the polymer was dried in a vacuum oven at 150 °C for 12 hours. The results are shown in Table 3.

[0134] Characterization of the Polymer Determination of Molecular Weight and Cyclic Dimer Content Size exclusion chromatography (SEC) was carried out using methylene chloride as the mobile phase. Two 5 μm mixed D size exclusion chromatography (SEC) columns with a guard column from Agilent Technologies were used for separation. A UV detector at 254 nm was used to obtain the chromatogram. A flow rate of 1.5 ml / min and an injection volume of 20 μL of a 0.2 w / v% solution in the mobile phase were selected.

[0135] Calibration was performed using 10 narrow calibration standards of polystyrene obtained from Agilent Technologies (peak molecular weight range: 371,000 - 580).

[0136] Calibration curve: 1) Type: Relative, calibrated with narrow calibration standards 2) Fit: Third-order regression.

[0137] Integration and calculation: Data, calibration, and molecular weight calculations were obtained using Waters Empower Pro GPC software. The peak integration start and end points were determined manually from the significant differences across the baseline.

[0138] Determination of melt stability and mechanical properties by compression molding Polymer strands were produced from isolated powders of various polymer compositions using a DSM Xplore® microcompounder under the following conditions: Barrel temperature (upper, middle, lower): 360 °C Screw speed 75 - 100 rpm Retention time 3 - 5 minutes

[0139] The polymer strands were cut into pellets 12.7 mm or less in size.

[0140] 102 mm × 102 mm × 3.2 mm plaques were made from the pelletized polymer by compression molding 45 g of the polymer under the following conditions: · Preheated at 338 °C, · 2041 kg-f at 338 °C for 15 minutes · 2268 kg-f at 338 °C for x minutes · Cooled to 30 °C at 2041 kg-f over 40 minutes.

[0141] A 102 mm×102 mm×3.2 mm compression-molded plaque was machined into six 12.7 mm×63.5 mm flexure test specimens and a 25 mm disk for parallel plate testing.

[0142] For flexure test specimens of various polymer compositions, six specimens were subjected to a flexure test at room temperature (i.e., 23 °C) at 2 mm / min according to ASTM method D790. In this method, a 50.8 mm span or gauge and a 5 mm load radius were utilized. The average of the six specimens is shown.

[0143] Melt stability was measured on 25 mm disks using a TA Instruments ARES G2 rheometer. Readings were taken at a 1.6 mm gap after 10 and 40 minutes of hold time at 380 °C. For the oscillatory time sweep analysis, a strain of 5.0% and a frequency of 10.0 rad / s were used. Melt stability, VR40, is measured by the ratio of the viscosity at 40 minutes to the viscosity at 10 minutes.

[0144] Determination of Yellowness Index by Compression Molding Under the following conditions, 50.8 mm×50.8 mm×1.6 mm plaques were made from 6 g of isolated powder of various polymer compositions: · Preheat at 338 °C, · 454 kg-f at 338 °C for 20 minutes · 499 kg-f at 338 °C for 2 minutes · Cool to 30 °C at 454 kg-f over 40 minutes

[0145] For compression-molded plaques of various polymer compositions, yellowness index analysis was performed according to ASTM E313 using an x-rite Color i7 spectrophotometer. The average of four readings is shown.

[0146] [Table 1]

[0147] [Table 2]

[0148]

Table 3

Claims

1. - At least one aromatic dihydroxy monomer (a1) containing 4,4'-isopropylidenediphenol; - At least one aromatic dihalogen sulfone monomer (a2) containing at least one dihalogen compound selected from the group consisting of 4,4'-dichlorodiphenyl sulfone (DCPDS) and 4,4'-difluorodiphenyl sulfone (DFDPS); - At least one carbonate component; - A solvent containing 1,3-dimethyl-2-imidazolidinone (DMI); A method for preparing a polysulfone (PSU) polymer by condensing in a reaction mixture (R Ｇ ), wherein the PSU polymer has a weight average molecular weight (Mw) in the range of 70,000 g / mol to 200,000 g / mol and a polydispersity index (PDI) of less than 4 (PDI is Mw / Mn) measured by size exclusion chromatography (SEC) using methylene chloride as the mobile phase, The method includes maintaining the reaction mixture (R at a temperature T Ｇ until it is heated to a temperature T Ｈ and maintaining the temperature of the reaction mixture (R Ｇ at this temperature for at least 20 minutes before raising the temperature of the reaction mixture (R Ｒ to the reaction temperature T Ｈ and T Ｒ satisfy 140 °C < T Ｈ < T Ｒ < 215 °C, The amount of the PSU polymer at the end of the condensation is at least 30% by weight based on the total weight of the PSU polymer and the solvent.

2. The method according to claim 1, wherein the monomer (a1) contains at least 50% by weight of 4,4'-isopropylidenediphenol based on the total weight of the monomer (a1).

3. The method according to claim 1 or 2, wherein the monomer (a2) contains at least 50% by weight of 4,4'-dichlorodiphenyl sulfone (DCPDS) based on the total weight of the monomer (a2).

4. The temperature is T Ｈ to T Ｒ The method according to any one of claims 1 to 3, wherein the step of raising the temperature is carried out over a time varying from 5 minutes to 5 hours.

5. Inequality (1) or (2): ・140 °C < T Ｈ < 190 °C (1) ・180 < T Ｒ < 215 °C (2) (However, when both inequalities (1) and (2) are satisfied, T Ｈ < T Ｒ is a condition) The method according to any one of claims 1 to 4, wherein at least one of them is satisfied.

6. The following inequality: T Ｈ < T Ｒ - 5 °C is satisfied. The method according to any one of claims 1 to 5.

7. The reaction mixture (R Ｇ ) does not contain any substance that forms an azeotrope with water. The method according to any one of claims 1 to 6.

8. The method according to any one of claims 1 to 7, wherein the molar ratio of component (a1) to component (a2) is 1.01 to 1.

05.

9. The PSU polymer has a yellowness index (YI) of less than 6.0 measured according to ASTM E313 using an x-rite Color i7 spectrophotometer. The method according to any one of claims 1 to 8.

10. The PSU polymer has a DMI content of from 1 ppm (wt) to less than 300 ppm (wt) based on the total weight of the PSU polymer. The method according to any one of claims 1 to 9. **Claim 11**: The method according to any one of claims 1 to 10, wherein the PSU polymer has a chlorine content bound to the polymer of less than 400 ppm (wt) based on the total weight of the PSU polymer. **Claim 12**: The method according to any one of claims 1 to 11, wherein the PSU polymer contains less than 1.15% by weight of cyclic oligomers and cyclic dimers based on the total weight of the PSU polymer.

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