Description

Process for preparing a poly(biphenyl ether sulfone) (PPSU) polymer Related applications

[0001] This application claims priority to US No. 62/672,776 filed on May 17, 2018 and to EP No. 18178636.9 filed on June 19, 2018, the whole content of each of these applications being incorporated herein by reference for all purposes.

Technical Field

[0002] The present disclosure relates to a process for preparing a poly(biphenyl ether sulfone) (PPSU) polymer having a number average molecular weight (Mn) of from 12,000 g/mol to 20,000 g/mol, a weight average molecular weight (Mw) of less than 25,000 g/mol and a

polydispersity (PDI) of less than 1.7. The present disclosure also relates to a PPSU obtained from said process, as well as to articles incorporating the PPSU.

Background Art

[0003] Poly(biphenyl ether sulfone) (PPSU) polymers belong to the group of high- performance thermoplastics and are characterized by good mechanical properties. PPSU is notably commercially available from Solvay Specialty Polymers LLC under the tradename Radel ^® . Many articles made from PPSU are today manufactured by injection molding or other molding process.

[0004] It is generally accepted in the art that the mechanical properties of the

PPSU depend upon its molecular weight and that the higher the molecular weight, the higher the mechanical properties. The consequence of a PPSU of high molecular weight is however that it exhibits high melt viscosity, which then makes PPSU less attractive for certain markets.

For injection molding of thin wall parts for example, it is still desirable to have a PPSU that has low melt viscosities, so that molding operations can be performed with improved flow and molding performance. Because of its high viscosity, PPSU is usually processed at a temperature between 360 and 400°C which is far beyond its Tg of 220°C. In the context of improving the sustainability of polymers, there is a need to limit the energy consumption during the manufacture of parts by injection molding, like decreasing the processing temperature.

[0005] US 6,228,970 (BP Amoco) describes PPSU having improved

polydispersity and reduced amounts of low molecular weight oligomeric materials, which can be prepared by adjusting the concentration of the monomer reactants in a solution polymerization reaction that can be used to make PPSU.

[0006] WO 2017/144550 (Solvay) describes a sulfone polymer having an

improved processability and mechanical properties compromise, by incorporation in the polymer backbone of bi- or poly-functional monomers of asymmetrical structure.

Summary of invention

[0007] An aspect of the present disclosure is directed to process for preparing a poly(biphenyl ether sulfone) (PPSU) polymer having a number average molecular weight (Mn) of from 12,000 g/mol to 20,000 g/mol, a weight average molecular weight (Mw) of less than 25,000 g/mol and a

polydispersity (PDI) of less than 1.7.

[0008] The applicant has found that the process of the present invention allows to obtain a PPSU having a low melt viscosity and good mechanical properties, notably impact resistance and tensile strength, which makes the PPSU obtained therefrom most useful for injection molding of thin wall parts. The PPSU of the present invention can also advantageously be processed at a lower temperature in comparison to other commercially available PPSU polymers. This constitututes in itself an advantage in terms of energy consumption and sustainable development.

[0009] The process of the present invention comprises the steps of:

(a) preparing a PPSU having a Mn of less than 11 ,000 g/mol, by condensation of at least one aromatic dihydroxy monomer (a1) comprising at least 4,4’-dihydroxybiphenyl, with at least one aromatic sulfone monomer (a2) comprising at least two halogen substituents,

(b) dissolving the PPSU obtained in step (a) in a polar solvent S _A ,

(c) adding a non-solvent SB that is miscible with SA in a weight ration SA/SB ranging from 55/45 to 75/25 over a period of time sufficient to create two distinct phases, and

(d) separating the phases and recovering the PPSU, for example by coagulation or devolatilization.

[0010] Another aspect of the present disclosure is a poly(biphenyl ether

sulfone) (PPSU) polymer obtainable by the process of the present invention, having a number average molecular weight (Mn) of from

12,000 g/mol to 20,000 g/mol, a weight average molecular weight (Mw) of less than 25,000 g/mol and a polydispersity index (PDI) of less than 1.7, wherein:

- Mn is calculated by the following formula: wherein [EG,] is the concentration of end-groups of the PPSU in pmol/g,

- Mw is calculated by GPC with light scattering according to the

ASTM D-4001-93 and

- PDI is the ratio Mw/Mn.

[0011] The present disclosure also relates to an article comprising a polymer composition which comprises at least the PPSU of the present invention. Description of embodiments

[0012] The present disclosure relates to a method for preparing a poly(biphenyl ether sulfone) (PPSU) polymer having a number average molecular weight (Mn) of from 12,000 g/mol to 20,000 g/mol, a weight average molecular weight (Mw) of less than 25,000 g/mol and a

polydispersity (PDI) of less than 1.7 and comprises at least the 4 following steps:

(a) preparing a PPSU having a Mn of less than 11 ,000 g/mol, by

condensation of at least one aromatic dihydroxy monomer (a1) comprising at least 4,4’-dihydroxybiphenyl, with at least one aromatic sulfone monomer (a2) comprising at least two halogen substituents,

(b) dissolving the PPSU obtained in step (a) in a polar solvent S _A ,

(c) adding a non-solvent SB that is miscible with SA in a weight ration SA/SB ranging from 55/45 to 75/25 over a period of time sufficient to create two distinct phases, and

(d) separating the phases and recovering the PPSU, for example by coagulation or devolatilization.

[0013] The method of the invention leads to high yield of PPSU of the invention in a limited period of time and can be implemented in existing industrial plants. The process of the present invention allows to obtain a PPSU a low melt viscosity. The PPSU obtained from the process of the present invention also surprisingly (especially in view of its low melt viscosity) presents good mechanical properties (notably impact resistance and tensile strength, as shown in the experimental part). This combination of technical features makes the PPSU of the present invention well suited for injection molding of thin wall parts for example. Due to its low melt viscosity, the PPSU of the present invention can be processed at a lower temperature (for example below 350°C) in comparison to other

commercially available PPSU polymers (about 380-420°C), which is an advantage in terms of energy consumption and sustainable development.

[0014] The expressions“(co)polymer” or“polymer” are hereby used to designate homopolymers containing substantially 100 mol.% of the same recurring units and copolymers comprising at least 50 mol.% of the same recurring units, 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.%.

[0015] In the present application:

- any description, even though described in relation to a specific

embodiment, is applicable to and interchangeable with other embodiments of the present disclosure; - where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list; and

- any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents.

[0016] The method of the present invention allows to obtain a PPSU

characterized in that:

- its number average molecular weight (Mn) ranges between 12,000 g/mol and 20,000 g/mol, for example between 12,500 g/mol and 19,000 g/mol or between 13,000 g/mol and 18,000 g/mol,

- its weight average molecular weight (Mw) is less than 25,000 g/mol, for example less than 24,000 g/mol, less than 23,000 g/mol or even less than 22,000 g/mol, and

- its PDI is less than 1.7, for example less than 1.6 or less than 1.5, wherein:

- Mn is calculated by the following formula: wherein [EG,] is the concentration of end-groups of the PPSU in pmol/g,

- Mw is calculated by GPC with light scattering according to the ASTM D-4001-93, and

- PDI is Mw/Mn.

[0017] The Mn of the PPSU of the present invention is determined by the end groups method. The end groups are moieties at respective ends of the PPSU polymer chain that are used to assess the Mn of the PPSU polymer— in particular, by measuring the concentration of the end groups to determine the number of moles of PPSU in a given weight of sample.

[0018] Depending on the method used for preparing the PPSU, and the possible use of an end-capping agent during the process, the PPSU may possess, for example, end-groups derived from the monomers and/or from end- capping agents.

[0019] As explained below, the PPSU of the invention can for example be

manufactured by condensation of at least one aromatic dihydroxy monomer (a1) comprising at least 4,4’-dihydroxybiphenyl with at least one aromatic sulfone monomer (a2) comprising at least two halogen

substituents, for example Cl or F. In this case, the end groups of the PPSU may include:

- hydroxyl groups,

- hydroxyl groups converted into alkoxy (e.g. methoxy) or aryloxy end groups when an end-capping agent is used, and

- halo-groups, such as chlorinated end groups or fluorinated end groups.

In this case therefore, the determination of the Mn of the PPSU will include:

- the determination of the concentration of hydroxyl groups, for example by titration,

- the determination of the concentration of alkoxy or aryloxy groups, for example by NMR with a C2D2CU solvent, and

- the determination of the concentration of halogen groups, for example using a halogen analyzer.

[0020] Generally, any suitable method may be used to determine the

concentration of the end groups.

[0021] The use of the end-group method to measure the Mn of the polymer is well-suited to obtain an accurate Mn value, and then of a meaningful PDI. The method is based on titration of the molecules present in the analysed sample, based on their end-groups, independently from the size of the molecules in the sample. The Mn determined according to this method is known to be more accurate than any other methods, for example the determination of Mn by GPC.

[0022] The weight average molecular weight (Mw) of the PPSU of the present invention is determined by GPC with light scattering according to the ASTM D-4001-93.

[0023] The PPSU polymer obtained through the method of the present invention is also characterized by its polydispersity index (“PDI” or“PDI index” herewith), also called sometimes polymolecularity index. The

polydispersity or polymolecularity corresponds to the molecular weight distribution of the various macromolecules within the polymer. The PDI index corresponds to the ratio Mw/Mn, the number average molecular weight Mn and weight average molecular weight Mw being determined by as detailed above.

[0024] For the purpose of the present invention, a poly(biphenyl ether

sulfone) (PPSU) denotes any polymer comprising recurring units (Rppsu) of formula (L):

where

- R, at each location, is independently selected from a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium;

- h, for each R, is independently zero or an integer ranging from 1 to 4.

[0025] According to an embodiment, R is, at each location in formula (L) above, independently selected from the group consisting of a C1-C12 moiety optionally comprising one or more than one heteroatoms; sulfonic acid and sulfonate groups; phosphonic acid and phosphonate groups; amine and quaternary ammonium groups. [0026] According to an embodiment, h is zero for each R. In other words, according to this embodiment, the recurring units (Rppsu) are units of formula (U):

[0027] According to another embodiment, the recurring units (Rppsu) are units of formula (L”):

[0028] The PPSU polymer of the present invention can therefore be a

homopolymer or a copolymer. If it is a copolymer, it can be a random, alternate or block copolymer.

[0029] According to an 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 recurring units in the PPSU are recurring units (Rppsu) of formula (L), (L’) and/or (L”).

[0030] When the poly(biphenyl ether sulfone) (PPSU) is a copolymer, it can be made of recurring units (R*PPSU), different from recurring units (Rppsu), such as recurring units of formula (M), (N) and/or (O):

[0031] The process of the present invention comprises at least 4 steps. It

comprises a first step of condensing monomers to prepare a PPSU of a certain Mn and it comprises additional steps of concentrating the fraction of the PPSU obtained in the first step.

[0032] Step (a) of the process of the present invention more precisely consists in preparing a PPSU having a Mn of less than 11 ,000 g/mol, by condensation of at least one aromatic dihydroxy monomer (a1) comprising at least 4,4’-dihydroxybiphenyl, with at least one aromatic sulfone monomer (a2) comprising at least two halogen substituents.

[0033] The PPSU obtained from step (a) has a Mn of less than 11 ,000 g/mol, for example less than 10,500 g/mol or less than 10,000 g/mol. Several options, detailed below, are available in the art to produce a sulfone polymer of a specific molecular weight. A modified Carothers equation:

where

Dp = degree of polymerization and

r = monomer ratio (a1):(a2) or (a2):(a1), with r<1

provides a means to calculate the monomer ratio (a1):(a2) necessary to produce the desired molecular weight Mn. Another option to produce a PPSU of a desired Mn is to stop the reaction after the desired Mn has been attained, using an activated aromatic halide or an aliphatic halide such as methyl chloride or benzyl chloride, and the like. The terminal hydroxyl groups of the polymer thereby convert into ether groups which stabilize the polymer for melt processing. Suitable end groups in the polycondensates are all chemically inert groups. To introduce the end groups, a small amount of an appropriate compound is introduced into the polycondensation mixture, advantageously after the desired degree of polycondensation has been reached. The use of aliphatic and aromatic halide, especially methyl chloride, is preferred. Another option yet to produce a PPSU of a desired Mn is to extend the condensation reaction time until the desired Mn has been attained. Another option to produce a PPSU of a desired Mn is to introduce at the beginning of the reaction a determined quantity of a monofunctional monomer containing a hydroxyl or halogen (Cl or F), for example phenol, 4-phenylphenol, 4-chlorophenyl phenyl sulfone.

[0034] The condensation of step (a) may be carried out in a solvent or the

condensation of step (a) can be solvent-free, that-is-to-say can be conducted in the melt, in the absence of a solvent.

[0035] When the condensation step (a) is solvent-free, the reaction can be carried out in equipment made from materials inert toward the monomers. In this case, the equipment is chosen in order to provide enough contact of the monomers, and in which the removal of volatile reaction products is feasible. Suitable equipment includes agitated reactors, extruders and kneaders, for example mixing kneaders from List AG or BUSS. The use of mixing kneaders may notably be useful to prepare a solvent-free PPSU for reasons of the residence time which can be longer than in an extruder.

The equipment may for example be operated at:

- a shear rate (i.e. velocity gradient in the kneading material in the gap between the rotating kneading element and the wall) in the range from 5 to 500 S ¹ , preferably from 10 to 250 s ^_1 , in particular from 20 to 100 s ^_1 , and

- a fill level (i.e. the proportion that is filled by the starting monomers of the volume capacity in the kneader which can be filled with monomers and which permits mixing) in the range from 0.2 to 0.8, preferably from 0.22 to 0.7, in particular from 0.3 to 0.7, specifically from 0.35 to 0.64.

[0036] When the condensation step (a) is carried out in a solvent, the solvent is for example a polar aprotic solvent selected from the group consisting of N-methylpyrrolidone (NMP), N,Ndimethylformamide (DMF),

N,N-dimethylacetamide (DMAC), 1 ,3-dimethyl-2-imidazolidinone, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), chlorobenzene and sulfolane. The condensation of step (a) is preferably carried out in sulfolane or NMP. [0037] The condensation of step (a) is preferably carried out in the presence of a base, for example selected from the group consisting of potassium carbonate (K2CO3), potassium tert-butoxide, sodium carbonate (Na2C03), cesium carbonate (CS2CO3) and sodium tert-butoxide. The base acts to deprotonate the component (a1) comprising at least

4,4’-dihydroxybiphenyl during the condensation reaction.

[0038] The condensation of step (a) is preferably carried out in the presence potassium carbonate (K2CO3), sodium carbonate (Na2C03) or a blend of both. According to an embodiment, the condensation of step (a) is carried out in the presence of a low particle size alkali metal carbonate, for example comprising anhydrous K2CO3, having a volume-averaged particle size of less than about 100 pm, for example less than 50 pm, less than 30 pm or less than 20 pm. According to a preferred embodiment, the condensation of step (a) is carried out in in the presence of a carbonate component comprising not less than 50 wt. % of K2CO3 having a volume- averaged particle size of less than about 100 pm, for example less than 50 pm, less than 30 pm or less than 20 pm, based on the overall weight of the base component in reaction mixture. The volume-averaged particle size of the carbonate used can for example be determined with a

Mastersizer 2000 from Malvern on a suspension of the particles in chlorobenzene/sulfolane (60/40).

[0039] The molar ratio (a1):(a2) may be from 0.9 to 1.1 , for example from 0.92 to 1.08 or from 0.95 to 1.05.

[0040] According to an embodiment of the process of the present invention, the monomer (a1) comprises, based on the total weight of the monomer (a1), at least 50 wt.% of 4,4’-dihydroxybiphenyl (biphenol), for example at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.% or at least 95 wt.% of 4,4’-dihydroxybiphenyl.

[0041] According to another embodiment of the process of the present invention, the monomer (a2) is a 4,4-dihalosulfone comprising at least one of a 4,4’-dichlorodiphenyl sulfone or 4,4’-difluorodiphenyl sulfone, preferably 4,4’-dichlorodiphenyl sulfone (DCDPS). [0042] According to another embodiment yet of the process of the present invention, the monomer (a2) comprises, based on the total weight of the monomer (a2), at least 50 wt.% of 4,4’-diclorodiphenyl sulfone (DCDPS), for example at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.% or at least 95 wt.% of DCPDS.

[0043] According to the condensation of step (a), the components of the reaction mixture are generally reacted concurrently. The reaction is preferably conducted in one stage. This means that the deprotonation of

monomer (a1) and the condensation reaction between the monomers (a1) and (a2) takes place in a single reaction stage without isolation of the intermediate products.

[0044] According to an embodiment of the process of the present invention, the condensation is carried out in a mixture of a polar aprotic solvent and a solvent which forms an azeotrope with water. The solvent which forms an azeotrope with water includes aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, chlorobenzene and the like. It is preferably toluene or chlorobenzene. The azeotrope forming solvent and polar aprotic solvent are used typically in a weight ratio of from about 1 :10 to about 1 : 1 , preferably from about 1 :5 to about 1 :1. Water is continuously removed from the reaction mass as an azeotrope with the azeotrope forming solvent so that substantially anhydrous conditions are maintained during the polymerization. The azeotrope-forming solvent, for example, chlorobenzene, is removed from the reaction mixture, typically by distillation, after the water formed in the reaction is removed leaving the PPSU dissolved in the polar aprotic solvent.

[0045] The temperature of the reaction mixture is kept at about 150°C to

about 350°C, preferably from about 210°C to about 300°C for about one to 15 hours.

[0046] The reaction mixture is polycondensed, within the temperature range, until the requisite degree of condensation is reached. The polycondensation time can be from 0.1 to 10 hours, preferably from 0.2 to 4 or from 0.5 to 2 hours, depending on the nature of the starting monomers and on the selected reaction conditions. [0047] The inorganic constituents, for example sodium chloride or potassium chloride or excess of base, can be removed, before or after isolation of the PPSU, by suitable methods such as dissolving and filtering, screening or extracting.

[0048] According to an embodiment, the amount of PPSU at the end of the

condensation is at least 30 wt.% based on the total weight of the PPSU and the polar aprotic solvent, for example at least 35 wt.% or at least or at least 37 wt.% or at least 40 wt.%.

[0049] At the end of the reaction, the PPSU polymer is separated from the other components (salts, base, ...) to obtain a PPSU solution. Filtration can for example be used to separate the PPSU polymer from the other components. The PPSU solution can then be used as such for step (b) or alternatively, the PPSU can be recovered from the solvent, for example by coagulation or devolatilization of the solvent.

[0050] Step (b) of the process of the present invention consists in dissolving the PPSU from step (a) in a polar solvent S _A . By“dissolving the PPSU in a polar solvent S _A ”, it is also understood that the PPSU solution obtained from step (a) can be diluted to the desired concentration, for example when the condensation solvent of step (a) is identical to the polar solvent S _A .

[0051] Step (b) can take place under agitation, in order to dissolve the polymer molecules faster and limit the generation of color. An inert gaz can also be used alternatively or in complement to agitation, for the same reasons.

[0052] The solvent SA may be selected from the group consisting of

N-methylpyrrolidone (NMP), N-butylpyrrolidone (NBP),

N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC),

1 ,3-dimethyl-2-imidazolidinone, tetrahydrofuran (TFIF), dimethyl sulfoxide (DMSO), chloroform, dichloromethane, chlorobenzene and sulfolane.

[0053] The solvent S _A is preferably NMP.

[0054] The PPSU can be dissolved at a temperature ranging from room

temperature up to the boiling point of the solvent, usually between 23°C and 150°C. The PPSU solution is then kept during step (b) at a

temperature ranging from about 20°C to about 100°C. [0055] The concentration of the PPSU in the solvent at the end of step (b) can range from 1 to 40 wt.%, preferentially from 2 to 20 wt.%, even more preferentially from 3 to 15 wt.%.

[0056] Step (c) of the process of the present invention consists in adding a non- solvent SB that is miscible with SA in a weight ration SA/SB ranging from 50/50 to 80/20 over a period of time sufficient to create two distinct phases.

[0057] According to an embodiment, the PPSU solution from step (b) is placed under agitation before introducing the solvent S _B .

[0058] The addition of the non-solvent S _B to the PPSU solution of step (b),

i.e. polar solvent SA, can take from 0.1 to 24 hours, for example from 0.5 to 10 hours, preferably less than 3 hours. The addition of the non-solvent S _B to the solvent SA can be done step-wise (or sequentially) or it can be done at a constant rate or a at a variable rate.

[0059] The solvent SB may be selected from the group consisting of water,

methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, acetone, ethylene glycol and 1 ,2-propanediol and 1 ,3-propanediol. A mixture of at least two solvents SB can also be used in the process of the present invention.

[0060] The solvent S _B is preferably methanol.

[0061] According to another embodiment, the weight ration SA/SB ranges from 55/45 to 75/25, from 57/43 to 73/27, for example from 60/40 to 70/30.

[0062] The temperature of the solution during step (c) is preferably kept from

about 20°C to about 100°C, preferentially from about 20°C to 60°C.

[0063] During the introduction of the solvent S _B (for example under agitation), two phases are created: a liquid phase and a second phase being either a solid or a liquid phase with a higher viscosity. According to step (d), the two distinct phases can then be separated and the PPSU is subsequently recovered by conventional techniques such as coagulation, solvent evaporation, and the like.

[0064] Steps (b) and (c) can be repeated several times in the preparation process of the PPSU of the present invention. [0065] Steps (b) and (c) of the process can also be partially combined, in such a way that part of the solvent SB used in step (c) can be used in step (b). According to this embodiment, part of the solvent SB is mixed with the solvent SA during step (b), for example just before dissolving the PPSU polymer obtained in step (a). In other words, according to this

embodiment, step (b) of the process of the present invention consists in dissolving the PPSU from step (a) in a blend of polar solvent SA and solvent SB, for example in a ratio SA:SB ranging from 99: 1 to 75:25 or from 95:5 to 80:20.

[0066] According to an embodiment, the process of the present invention not only allow to obtain a PPSU of a certain Mw, Mn and IP, but also the so- obtained PPSU comprises less than 1 wt.% of oligomers having a molecular weight of less than 4,000 g/mol, based on the total weight of PPSU polymers, for example less than 0.9 wt.%, less than 0.8 wt.%, less than 0.7 wt.% or even less than 0.5 wt.% 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.

[0067] According to another embodiment, the process of the present invention allows to obtain a PPSU also having:

- a viscosity of less than 1 ,000 Pa.s at 100 s ^_1 , for example less than 900 Pa.s at 100 s ^_1 , less than 800 Pa.s at 100 s ^-1 or less than 700 Pa.s at 100 S ¹ , as measured at 360°C according to ASTM D3835,

- a notched Izod impact strength of at least 2 ft. Ib/in, for example at least 4ft. Ib/in, at least 5ft. Ib/in or at least 7ft. Ib/in, as measured according to ASTM D638, and/or

- an tensile elongation at break of at least 5%, at least 10%, at least 15% or at least 20%, as measured according to ASTM D256.

[0068] According to an embodiment of the present invention, the PPSU

comprises less than 1 wt.% of oligomers according to formula (C):

where

• alternative 1 :

- n is an integer from 1 to 10, and

- X is H or Chta and Y is Cl or OH or OCH3, or

• alternative 2:

- n is an integer from 2 to 10, and

- Y and X form a bond (cyclic oligomers),

for example less than 0.9 wt.%, less than 0.8 wt.%, less than 0.7 wt.% or even less than 0.5 wt.% of oligomers according to formula (C).

[0069] The content of oligomers in the reaction mixture can be assed because the oligomers elute as the two major resolved components after the elution of the PPSU and prior to the elution of polymerization reaction solvent, if any is present, when analyzed by size exclusion liquid chromatography. SEC chromatography can be performed using a P1 gel 5 pm mixed-D,

300 x 7.5 mm column available from Polymer laboratories with methylene chloride as the elutant.

[0070] PPSU polymer, compositions and articles

[0071] The present invention also relates to the PPSU having a number average molecular weight (Mn) of from 12,000 g/mol to 20,000 g/mol, a weight average molecular weight (Mw) of less than 25,000 g/mol and a

polydispersity index (PDI) of less than 1.7,

wherein:

- Mn is calculated by the following formula: wherein [EG,] is the concentration of end-groups of the PPSU in pmol/g,

- Mw is calculated by GPC with light scattering according to the

ASTM D-4001-93 and

- PDI is the ratio Mw/Mn.

[0072] According to an embodiment, this PPSU is obtained from the preparation process described above.

[0073] According to another embodiment, this PPSU presents: - a viscosity of less than 1 ,000 Pa.s at 100 s ^-1 , for example less than 900 Pa.s at 100 s ^-1 , less than 800 Pa.s at 100 s ^-1 or less than 700 Pa.s at 100 S ¹ , as measured at 360°C according to ASTM D3835,

- a notched Izod impact strength of at least 2 ft. Ib/in, for example at least 4ft. Ib/in, at least 5ft. Ib/in or at least 7ft. Ib/in, as measured according to ASTM D638, and/or

- an tensile elongation at break of at least 5%, at least 10%, at least 15% or at least 20%, as measured according to ASTM D256.

[0074] The present invention also relates to a polymer composition (C)

comprising the PPSU of the present invention, as described above, as well as to articles comprising the polymer composition (C) which comprises at least the PPSU of the invention.

[0075] The polymer composition (C) may comprise PPSU in an amount of at least 1 wt. %, for example at least 5 wt. %, at least 10 wt. %, at least 15 wt. %, at least 20 wt. %, at least 25 wt. %, or at least 30 wt. %, based on the total weight of the polymer composition (C).

[0076] The polymer composition (C) may comprise PPSU in an amount of more than 50 wt. %, for example more than 55 wt. %, more than 60 wt. %, more than 65 wt. %, more than 70 wt. %, more than 75 wt. %, more than

80 wt. %, more than 85 wt. %, more than 90 wt. %, more than 95 wt. % or more than 99 wt. %, based on the total weight of the polymer

composition (C).

[0077] According to an embodiment, the polymer composition (C) comprises

PPSU in an amount ranging from 1 to 99 wt. %, for example from 3 to 96 wt. %, from 6 to 92 wt. % or from 12 to 88 wt. %, based on the total weight of the polymer composition (C).

[0078] The polymer composition (C) may further optionally comprise one or more additional additives selected from the group consisting of ultraviolet light stabilizers, heat stabilizers, acid scavengers (i.e. zinc oxide, magnesium oxide), antioxidants, pigments, processing aids, lubricants, flame

retardants, and/or conductivity additive (i.e. carbon black and carbon nanofibrils). [0079] The polymer composition (C) may also further comprise other polymers than PPSU, for example another sulfone polymer, e.g. polysulfone (PSU), polyethersulfone (PES), or a polyphenylene sulfide (PPS), a poly(aryl ether ketone) (PAEK), e.g. a poly(ether ether ketone) (PEEK), a poly(ether ketone ketone) (PEKK), a poly(ether ketone) (PEK) or a copolymer of PEEK and poly(diphenyl ether ketone) (PEEK-PEDEK copolymer), polyetherimide (PEI), and/or polycarbonate (PC).

[0080] The polymer composition (C) may further comprise flame retardants such as halogen and halogen free flame retardants.

[0081] The polymer composition (C) may comprise glass fibers, for

example E-glass fibers or high modulus glass fibers having an elastic modulus (also called 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 comprise high modulus glass fibers selected from the group consisting of R, S and T glass fibers, for example in an amount of at least 5 wt. %, for example 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 polymer composition (C1).

[0082] The polymer composition (C) can be made by methods well known to the person of skill in the art. For example, such methods include, but are not limited to, melt-mixing processes. Melt-mixing processes are typically carried out by heating the polymer components above the melting temperature of the thermoplastic polymers thereby forming a melt of the thermoplastic polymers. In some embodiments, the processing

temperature ranges from about 280-450°C, preferably from about

290-400°C, from about 300-360°C or from about 310-340°C. Suitable melt-mixing apparatus are, for example, kneaders, Banbury mixers, single- screw extruders, and twin-screw extruders. Preferably, use is made of an extruder fitted with means for dosing all the desired components to the extruder, either to the extruder's throat or to the melt. The components of the polymer composition are fed to the melt-mixing apparatus and melt- mixed in that apparatus. The components may be fed simultaneously as a powder mixture or granule mixer, also known as dry-blend, or may be fed separately.

[0083] The order of combining the components during melt-mixing is not

particularly limited. In one embodiment, the component can be mixed in a single batch, such that the desired amounts of each component are added together and subsequently mixed. In other embodiments, a first sub-set of components can be initially mixed together and one or more of the remaining components can be added to the mixture for further mixing. For clarity, the total desired amount of each component does not have to be mixed as a single quantity. For example, for one or more of the

components, a partial quantity can be initially added and mixed and, subsequently, some or all of the remainder can be added and mixed.

[0084] The polymer composition (C) may be well suited for the manufacture of articles useful in a wide variety of applications. For example, the high- flow, toughness, and chemical resistance properties of the polymer composition makes it especially suitable for use in thin walled articles, structural components for mobile electronic devices (e.g., framework or housing), thermoplastic continuous fiber composites (e.g. for aeronautics and automotive structural parts), medical implants and medical devices, and shaped articles made by additive manufacturing methods as discussed below.

[0085] In some aspects, the shaped articles may be made from the polymer

composition using any suitable melt-processing method such as injection molding, extrusion molding, roto-molding, or blow-molding.

[0086] According to an embodiment, the article of the present invention has been molded by injection.

[0087] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0088] Exemplary embodiments will now be described in the following non-limiting examples. [0089] EXAMPLES

[0090] The disclosure will be now described in more detail with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the disclosure.

[0091] Starting Materials

[0092] The following polymers were prepared:

[093] PPSU #1 (comparative), a poly(biphenyl ether sulfone) (PPSU) with a Mn of 9,877 g/mol and a PDI of 1.82, was prepared according to the following process:

In a 4L four-neck flask fitted with a mechanical stirrer, Dean-Stark trap, condenser and nitrogen inlet, 400 g of 4,4’-biphenol, 642.57 g of

4,4’-dichlorodiphenyl sulfone and 320.64 g of potassium carbonate were placed in 2,007 g of sulfolane. A slight stream of nitrogen was applied above the reaction mixture through one of the necks of the flask with an exit through a bubbler above the condenser. The reaction mixture was stirred with an overhead mechanical agitator and warmed using an oil bath controlled at the appropriate temperature. The bath temperature increased from room temperature to 215°C over 60 minutes and held at the reaction temperature for 4 hours.

The reaction mixture was cooled down to 150°C, diluted with 2,000 g of sulfolane, further cooled down to 100°C and filtered.

The PPSU was then recovered by coagulation. The PPSU in sulfolane solution was poured all at the same time into a Waring blender containing a 50/50 v/v mixture of water and methanol, in order to induce precipitation. The resulting off-white solid was then isolated by filtration, and washed three times in the Waring blender with hot deionized water (70°C) and twice with methanol with filtration between each wash.

[0094] PPSU #2 (inventive), a poly(biphenyl ether sulfone) (PPSU) with a Mn of 15,049 g/mol and a PDI of 1.41 , prepared according to the following process with a ratio SA/SB equals to 65/35:

In a 20L vessel under agitation and inerted by a nitrogen blanket were added 600 g of PPSU#1 and 9,120 g of NMP (solvent S _A ). 2,280 g of methanol (solvent S _B ) was first introduced in the vessel. After dissolution under agitation at room temperature, 2,631 g of methanol (solvent S _B ) was introduced at a rate of 111 mL/min (during about 23 min). After 5 min agitation, the stirrer was stopped: the reaction mixture presented a viscous layer at the bottom of the flask and a liquid layer at the top.

The viscous layer was recovered by extrusion of the bottom of the flask and diluted with 1.5 L of NMP.

PPSU #2 is then recovered by coagulation of the diluted viscous layer using a similar recovery process as described for PPSU #1. Yield : 72%.

[0095] PPSU #3 (comparative): a PPSU commercialized by Solvay Specialty

Polymers under the name Radel ^® R5600 with a Mn of 12,480 g/mol and a PDI of 2.05.

[0096] PPSU #4 (comparative): a poly(biphenyl ether sulfone) (PPSU) with a Mn of 17,620 g/mol and a PDI of 1.68, prepared according to the following process:

PPSU#4 was obtained by submitting PPSU#3 to the steps described for PPSU #2.

[0097] Characterization of the PPSU

[0098] Determination of the Mn by End Group Analysis

[0099] Hydroxy! titration

Hydroxyl groups were analyzed by dissolving a sample of the polymer in 5ml of sulfolane : monochloro benzene (50:50). 55 ml of methylene chloride was added to the solution and it was titrated with tetrabutyl ammonium hydroxide in toluene potentiometrically using Metrohm

Solvotrode electrode & Metrohm 686 Titroprocessor with Metrohm 665 Dosimat. There were three possible equivalence points. The first equivalence point was indicative of strong acid. The second equivalence point was indicative of sulfonic hydroxyls. The third equivalence point was indicative of phenolic hydroxyls. Total hydroxyl numbers are calculated as a sum of phenolic and sulfonic hydroxyls.

[00100] Chlorine Analysis

Chlorine end groups were analyzed using a ThermoGLAS 1200 TOX halogen analyzer. Samples between 1mg and 10mg were weighted into a quartz boat and inserted into a heated combustion tube where the sample was burned at 1000°C in an oxygen stream. The combustion products were passed through concentrated sulfuric acid scrubbers into a titration cell where hydrogen chloride from the combustion process was absorbed in 75% v/v acetic acid. Chloride entering the cell was then titrated with silver ions generated coulometrically. Percent chlorine in the sample was calculated from the integrated current and the sample weight. The resulting percent chlorine value was converted to chlorine end group concentration in micro equivalents per gram.

[00101] Methoxy end-group concentration

It is determined by NMR with a C2D2CL solvent.

[00102] The concentration of end-groups and respective calculated Mn of the

PPSU described in the examples are listed in Table 1.

[00103] Determination of Mw by Light Scattering GPC

A Viscotek GPC Max with a TDA302 Triple detector array comprised of RALS (Right Angle Light Scattering), Rl and Viscosity detectors was used. NMP with 0.2 w/w% LiBr at 65oC at 1.0 mL/min was run through

3 columns: a guard column (CLM1019 - with a 20k Da exclusion limit), a high Mw column (CLM1013 exclusion of 10MM Daltons relative to Poly Styrene), and a low Mw column (CLM1011 - exclusion limit of 20k Daltons relative to PS). Calibration was done with a single, mono-disperse polystyrene standard of ~100k Da.

[00104] The samples were a concentration of about 2 mg/mL in NMP/ LiBr. The Mw of the PPSU described in the examples are listed in Table 1.

Table 1

[00105] Evaluation of Rheological and Mechanical Properties

[00106] Rheological properties were assessed at 360°C at 100 s- ¹ according to ASTM D3835.

[00107] Mechanical properties were tested using injection molded 0.125

in (3.2 mm) thick ASTM test specimens which consisted of Type I tensile bars. The following ASTM test methods were employed in evaluating the mechanical properties of the formulations:

D638 : Tensile properties

D256 : Izod impact resistance (notched and unnotched)

[00108] PPSU #4 exhibit a too high viscosity, making it not suitable for injection molding of thin wall parts.

[00109] While both PPSU #2 and PPSU #3 were successfully injection molded into ASTM D638 Type I bar in a mold regulated at 160°C on a 110 ton Toyo IMM, PPSU#1 was too britle to successfully produce molded parts

(insufficient mechanical properties).

[00110] Results for PPSU #2 and PPSU#3 are shown in Table 2.

Table 2

[00111] PPSU #2 (inv) has a lower Mw than PPSU #3 (comp), but anyhow

presents comparable tensile and impact properties, as shown in Table 2.

[00112] PPSU #2 (inv) also has a lower PDI and exhibits a much lower melt

viscosity at 360°C (-50% vs. PPSU #3) which makes PPSU #2 most useful to be processed at lower temperature or to be used for injection molding of thin wall parts.

[00113] PPSU#2 was extruded into strand that were pelletized on a Brabender ^® Intelli-Torque Plasti-Corder ^® Torque Rheometer extruder equipped with a 0.75” 32 L/D general purpose single screw. The four heating zone were regulated only at 180-270-300-300°C, providing a melt temperature of 322°C, which can be considered as a low processing temperature in comparison to other commercially available PPSU polymers. This constitutes in itself an advantage in terms of energy consumption.