METHOD OF PREPARIN8 A POLY(ARYLENE ETHER)1 APPARATUS THEREFOR1 AND POLY(ARYLENE ETHER) PREPARED THEREBY
BACK8ROUND
Poly(arylene ether) resins may be prepared by the oxidative polymerization of a monohydric phenol in the presence of a solvent to form a solution in which the product poly(arylene ether) is soluble. The poly(arylene ether) may then be isolated by combinin8 the solution with an antisolvent to precipitate the poly(arylene ether). In practice1 it is very challen8in8 to control these precipitations to provide a final poly(arylene ether) solid havin8 consistent particle size.. In particular1 there is a need for a method of precipitatin8 a poly(arylene ether) that reduces the amount of undesirably fine particles.
BRIEF SUMMARY
The above-described and other drawbacks and disadvanta8es are alleviated by a method comprisin8: combinin8 a poly(arylene ether) solution with an antisolvent to form a poly(arylene ether) dispersion comprisin8 a poly(arylene ether) solid; wherein the poly(arylene ether) solution comprises a poly(arylene ether) and a solvent; and wherein said combinin8 comprises mixin8 with a shear rate of 8reater than 201000 reciprocal seconds (sec"1).
Other embodiments1 includin8 an apparatus for carryin8 out the method1 are described in detail below.
BRIEF DESCRIPTION OF THE DRAWIN8
FI8. 1 is a simplified dia8rammatic view of a poly(arylene ether) isolation apparatus 10 includin8 a hi8h-shear mixin8 pump 50 for combinin8 a poly(arylene ether) solution and an antisolvent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Havin8 extensively studied the precipitation of poly(arylene ether) resins under laboratory-scale1 pilot plant1 and manufacturin8 conditions1 the present inventors have observed that it can be very difficult to control the precipitation process in order to provide an isolated poly(arylene ether) resin havin8 a low content of particles smaller than 38 micrometers ("fines"). It is desirable to reduce fines because their presence
may be associated with losses of the poly(arylene ether) durin8 filtration and dryin8 sta8es. Other methods may allow the isolation of powders havin8.low content of finesj but they are not readily and economically adaptable to a lar8e-scale manufacturin8 facility. There remains a need for an economical poly(arylene ether) preparation method that produces poly(arylene ether) powders havin8 a reduced content of fines.
The present inventors have surprisin8ly found that a pbly(arylene ether) precipitate with reduced fines content may be obtained by combinin8 a poly(arylene ether) solution and an antisolvent at a shear rate of 8reater than 201000 sec"1. This result is particularly surprisin8 because the hi8h shear rate mi8ht have been expected to cause particle attribution and therefore undesirably small particle sizes. The shear rate is preferably 8reater than 501000 sec"11 more preferably at least about 601000 sec"11 still more preferably at least about 751000 sec"11 even more preferably at least about 1001000 sec"11 yet more preferably at least about 1251000 sec"1. In one embodiment1 the shear rate is less than about 5001000 sec"11 preferably less than about 3501000 sec"11 even more preferably less than about 2501000 sec"1. The desired hi8h shear may be achieved usin8 a pump comprisin8 a stator and a rotor. The shear rate may then be defined by the equation
shear rate = V x 1000/W
where shear rate is expressed in units of sec"11 V is the circumferential linear velocity of the rotor1 in meters per second1 and W is the 8ap width defined by the stator and the rotor1 in millimeters. In one embodiment1 the stator and the rotor define a 8ap width of about 0.01 to about 1 millimeter. Within this ran8e1 the 8ap width may preferably be at least about 0.05 millimeter1 more preferably at least about 0.10 millimeter. Also within this ran8e1 the 8ap width may preferably be up to about 0.5 millimeter1 more preferably up to about 0.25 millimeter. In another embodiment1 the rotor has a circumferential linear velocity of about 1 to about 100 meters per second. Within this ran8e1 the velocity may preferably be at least about 5 meters per second1 more preferably at least about 10 meters per second. Also within this ran8e1 the velocity may preferably be up to about 60 meters per second1 more preferably up to about 40 meters per second. Apparatus suitable for performin8 the hi8h-shear combination of the poly(arylene ether) solution and the antisolvent is described1 for example1 in European Patent No. 1351697 Bl to Schreiber. Suitable apparatus is also commercially available as1 for example1 the Siefer Tri8onal SM 180 centrifu8al pump from Wilhelm Siefer 8mbH & Co.1 Velbert1 8ermany.
There is no particular limit on the ratio in which the poly(arylene ether) solution and the ahtisolvent are combined. In one embodiment1 the poly(arylene ether) solution and the antisolvent are combined in a wei8ht ratio of about 1:1 to about 1:10. Within this ran8e1 the ratio may preferably be at least about 1:81 more preferably at least about 1:6. Also within this ran8e1 the ratio may preferably be up to about 1:21 more preferably up to about 1:3. In another embodiment1 the poly(arylene ether) solution and the antisolvent are combined in a volume ratio of about 1:1 to about 1:10. Within this ran8e1 the ratio may preferably be at least about 1:81 more preferably at least about 1:6. Also within this ran8e1 the ratio may preferably be up to about 1:21 more preferably up to about 1:3.
The temperatures of the poly(arylene ether) solution and the antisolvent immediately before they are combined will vary accordin8 to many factors1 includin81 for example1 the poly(arylene ether) composition1 the poly(arylene ether) intrinsic viscosity1 the poly(arylene ether) concentration in the solution1 the solvent type1 the antisolvent type1 and the wei8ht ratio of poly(arylene ether) solution to antisolvent. In one embodiment1 the method comprises combinin8 the poly(arylene ether) at a temperature of about 60 to about 100°C with the antisolvent at a temperature of about 15 to about 60°C. Within these ran8es1 the poly(arylene ether) solution temperature may be at least about 70°C1 or at least about 80°C; and the poly(arylene ether) solution temperature may be up to about 95°C1 or up to about 90°C. Also within these ran8es1 the antisolvent temperature may be at least about 20°C1 or at least about 25°C; and the antisolvent temperature may be up to about 55°C1 or up to about'50°C. The temperature of the combined poly(arylene ether)-antisolvent mixture may preferably be about 30 to about 55°C.
There is no particular limit on the type of poly(arylene ether) used in the method. The term poly(arylene ether) includes polyphenylene ether (PPE) and poly(arylene ether) copolymers; 8raft copolymers; poly(arylene ether) ether ionomers; and block copolymers of alkenyl aromatic compounds1 vinyl aromatic compounds1 and poly(arylene ether)1 and the like; and combinations comprisin8 at least one of the fore8oin8; and the like. Poly(arylene ether)s per se1 are known polymers comprisin8 a plurality of structural units of the formula
wherein for each structural unit1 each Q1 is independently halo8en1 primary or secondary lower alkyl (e.8.1 alkyl containin8 up to 7 carbon atoms)1 phenyl1 haloalkyl1 aminoalkyl1 hydrocarbonoxy1 halohydrocarbonoxy wherein at least two carbon atoms separate the halo8en and oxy8en atoms1 or the like; and each Q2 is independently hydro8en1 halo8en1 primary or secondary lower alkyl1 phenyl1 haloalkyl1 hydrocarbonoxy1 halohydrocarbonoxy wherein at least two carbon atoms separate the halo8en and oxy8en atoms1 or the like. Preferably1 each Q1 is alkyl or phenyl1 especially CM alkyl1 and each Q2 is hydro8en. In one embodiment1 each Q1 is methyl and each Q2 is hydro8en or methyl. In another embodiment1 each Q1 is methyl and each Q2 is hydro8en.
Both homopolymer and copolymer poly(arylene ether) are included. The preferred homopolymers are those containin8 216-dimethylphenylene ether units. Suitable copolymers include random copolymers containin81 for example1 such units in combination with 21316-trimethyl-l14-phenylene ether units or copolymers derived from copolymerization of 216-dimethylphenol with 21316-trimethylphenol. Also included are poly(arylene ether) containin8 moieties prepared by 8raftin8 vinyl monomers or polymers such as polystyrenes1 as well as coupled poly(arylene ether) in which couplin8 a8ents such as low molecular wei8ht polycarbonates1 quinqnes1 heterocycles and formal s under8o reaction in known manner with the hydroxy 8roups of two poly(arylene ether) chains to produce a hi8her molecular wei8ht polymer. Poly(arylene ether)s of the present invention further include combinations comprisin8 at least one of the above.
In one embodiment1 the poly(arylene ether) is the polymerization product of the at least one monohydric phenol and a dihydric phenol havin8 the structure
wherein D is a divalent aromatic radical. In one embodiment D has the structure
(wherein A1 represents an aromatic 8roup such as phenylene1 biphenylene1 naphthylene1 etc. In some embodiments E may be an alkylene or alkylidene 8roup includin81 for example1 methylene1 ethylene1 ethylidene1 propylene1 propylidene1 isopropylidene1 butylene1 butylidene1 isobutylidene1 amylene1 amylidene1 isoamylidene. When E is an alkylene or alkylidene 8roup1 it may also consist of two or more alkylene or alkylidene 8roups connected by a moiety different from alkylene or alkylidene1 such as an aromatic linka8e; a tertiary amino linka8e; an ether linka8e; a carbonyl linka8e; a silicon-containin8 linka8e; or a sulfur-containin8 linka8e includin81 but not limited to1 sulfide1 sulfoxide1 sulfone; or a phosphorus-containin8 linka8e includin81 but not limited to1 phosphinyl1 phosphonyl. In other embodiments E may be a cycloaliphatic 8roup includin81 but not limited to1 cyclopentylidene1 cyclohexylidene1 31315-trimethylcyclohexylidene1 methylcyclohexylidene1 2-[2.2.1]-bicycloheptylidene1 neopentylidene1 cyclopentadecylidene1 cyclododecylidene1 adamantylidene; a sulfur-containin8 linka8e1 such as sulfide1' sulfoxide or sulfone; a phosphorus-containin8 linka8e1 such as phosphinyl or phosphonyl; an ether linka8e; a carbonyl 8roup; a tertiary nitro8en 8roup; or a silicon-containin8 linka8e such as silane or siloxy. R1 represents hydro8en or a monovalent hydrocarbon 8roup such as alkyl1-aryl1 aralkyl1 alkaryl1 or cycloalkyl. In various embodiments a monovalent hydrocarbon 8roup of R1 may be halo8en-substituted1 particularly fluoro- or chloro-substituted1 for example as in dichloroalkylidene. Each occurrence of Y1 may be an inor8anic atom includin81 but not limited to1 halo8en (fluorine1 bromine1 chlorine1 iodine); an inor8anic 8roup includin81 but not limited to1 nitro; an or8anic 8roup includin81 but not limited to1 a monovalent hydrocarbon 8roup such as alkyl1 aryl1 aralkyl1 alkaryl1 or cycloalkyl1 or an oxy 8roup such as OR2 1 wherein R2 is a monovalent hydrocarbon 8roup such as alkyl1 aryl1 aralkyl1 alkaryl1 or cycloalkyl. In some particular embodiments Y1 comprises a halo 8roup or C1-C6 alkyl 8roup. The letter "m" represents any inte8er from and includin8 zero throu8h the number of positions on A ' available for substitution; "p" represents an inte8er from and includin8 zero throu8h the number of positions on E available for substitution; "t" represents an inte8er equal to at least one; "s" is either zero or one; and "u" represents any inte8er includin8 zero.
When more than one Y1 substituent is present1 they may be the same or different. When more than one R' substituent is present1 they may be the same1 or different. Where "s" is zero and "u" is not zero1 the aromatic rin8s are directly joined by a covalent bond with no intervenin8 alkylidene or other brid8e. The positions of the
.»
hydroxyl 8roups and Y1 on the aromatic residues A1 can be varied in the brtho1 meta1 or para positions and the 8roupin8s can be in vicinal1 asymmetrical or symmetrical relationship1 where two or more rin8 carbon atoms of the aromatic residue are substituted with Y1 and hydroxyl 8roups.
Some illustrative1 non-limitin8 examples of dihydric phenols include the dihydroxy-
substituted aromatic hydrocarbons disclosed by name or formula (8eneric or specific)
in U.S. Pat. No. 412171438 to Brunelle et al. Suitable dihydric phenols include1 for
example1 6-hydroxy-l-(4'-hydroxyphenyl)-l1313-trimethylindane1 414'-(31315-
trimethylcyclohexylidene)diphenol; 111 -bis(4-hydroxy-3-methylphenyl) cyclohexane;
212-bis(4-hydroxyphenyl)propane (commonly known as bisphenol-A); 414-bis(4-
hydroxyphenyl)heptane; 212-bis(4-hydroxy-315-dimethylphenyl) propane; 212-bis(4-
hydroxy-3-methylphenyl)propane; 212-bis(4-hydroxy-3- ethylphenyl)propane; 212-
bis(4-hydroxy-3-isopropylphenyl)propane; 214'- dihydroxydiphenylmethane; bis(2-
hydroxyphenyl)methane; bis(4-hydroxy- phenyl)methane; bis(4-hydroxy-5-
nitrophenyl)methane; bis(4-hydroxy-216- dimethyl-3-methoxyphenyl)methane; 111-
bis(4-hydroxyphenyl)ethane; 111- bis(4-hydroxy-2-chlorophenyl)ethane; 212-bis(3-
phenyl-4-hydroxyphenyl)- propane; bis(4-hydroxyphenyl)cyclohexylmethane; 212-
bis(4-hydroxyphenyl)- 1-phenyipropane; 31513'15'-tetrachloro-414'-
dihydroxyphenyl)propane; 214'- dihydroxyphenyl sulfone; 216-dihydroxy naphthalene; 616'-dihydroxy-31313'1 3'-tetramethyl-l1r-spirobiindane (sometimes know as "Sfel"); hydroquinone; resorcinol; and C1-Cj alkyl-substituted resorcinols. In a particular embodiment the dihydric phenol comprises bisphenol-A. Suitable dihydric phenols also include those containin8 indane structural units such as1 for example1 is 3-(4-hydroxyphenyl)-11113-trimethylindan-5-ol1 and 1 -(4-hydroxyphenyl)-11313-trimethylindan-5-ol.
The poly(arylene ether) is typically prepared by the oxidative couplin8 of at least one monohydroxyaromatic compound such as 216-xylenol or 21316-trimethylphenol. Catalyst systems are 8enerally employed for such couplin8; they typically contain at least one heavy metal compound such as a copper1 man8anese or cobalt compound1 usually in combination with various other materials. The method may1 optionally1 further comprise preparin8 the poly(arylene ether).
Particularly useful.poly(arylene ether)s for many purposes are those that comprise molecules havin8 at least one aminoalkyl-containin8 end 8roup. The aminoalkyl radical is typically located in an ortho position to the hydroxy 8roup. Products containin8 such end 8roups may be obtained by incorporatin8 an appropriate primary or secondary monoamine such as di-n-butylamine or dimethylamine as one of the constituents of the oxidative couplin8 reaction mixture. Also frequently present are 4-hydroxybiphenyl end 8roups1 typically obtained from reaction mixtures in which a byproduct diphenoquinorie is present1 especially in a coppep-halide-secondary or tertiary amine system. A substantial proportion of the polymer molecules1 typically constitutin8 as much as about 90% by wei8ht of the polymer1 may contain at least one of the aminoalkyl-containin8 and 4-hydroxybiphenyl end 8roups.
There is no particular limit on the intrinsic viscosity of the poly(arylene ether). For example1 the poly(arylene ether) may have an intrinsic viscosity measured at 25°C in chloroform of about 0.05 to about 1.0 deciliters per 8ram (dL/8). Within the ran8e1 the intrinsic viscosity may be at least about 0.11 0.21 0.31 or 0.35 dL/8. Also within this ran8e1 the intrinsic viscosity may be up to about 0.81 0.651 or 0.5 dL/8. The method is particularly useful for controllin8 the precipitation of low intrinsic viscosity pply(arylene ether) resins. Thus1 in one embodiment1 the poly(arylene ether) has an intrinsic viscosity of about 0.05 dL/8 to about 0.3 dL/8. In another embodiment1 the poly(arylene ether) comprises about 90 to about 99.9 wei8ht percent of a first poly(arylene ether) havin8 an intrinsic viscosity of about 0.05 to 0.3 deciliters per 8ram and about 0.1 to about 10 wei8ht percent of a second poly(arylene ether) havin8 an intrinsic viscosity of 8reater than 0.3 to about 1.0 deciliters per 8ram.
The poly(arylene solution) may comprise any concentration of poly(arylene ether). For example1 the poly(arylene ether) solution may comprise about 10 to about 70 wei8ht percent of the poly(arylene ether)1 based on the total wei8ht of the poly(arylene ether) solution. Within this ran8e1 the poly(arylene ether) concentration may be at least about 20 wei8ht percent1 or at least about 40 wei8ht percent. Also within this ran8e1 the poly(arylene ether) concentration may be up to about 60 wei8ht percent1 or up to about 50 wei8ht percent. The optimum poly(arylene ether) concentration will depend on variables includin8 the poly(arylene ether) composition1 the poly(arylene ether) intrinsic viscosity1 and the identity of the solvent.
There is no particular limit on the solvent employed in the method. Suitable or8anic solvents include aliphatic alcohols1 ketones1 aliphatic and aromatic hydrocarbons1 chlorohydrocarbons1 nitrohydrocarbons1 ethers1 esters1 amides1 mixed ether-esters1
sulfoxides1 and the like1 and combinations thereof. In a preferred embodiment1 the solvent comprises a C6-Cl8 aromatic hydrocarbon1 includin81 for example1 toluene1 xylenes1 and the like1 and mixtures thereof. A hi8hly preferred solvent is toluene.
In one embodiment1 the solvent comprises1 based on the total wei8ht of-the solvent1 about 70 to about 99.9 wei8ht percent of a C6-C18 aromatic hydrocarbon1 and about 0.1 to about 30 wei8ht percent of a poor solvent such as1 for example1 a C1-C10 alkanol1 a C3-C10 ketone1 a Cj-C10 alkane1 or the like1 or a mixture thereof. In one embodiment1 the poor solvent comprises a C3.-C8 aliphatic alcohol such as1 for example1 n-propanol1 isopropanol1 n-butanol1 t-butanol1 n-pentanol1 or the like1 or a combination thereof. A preferred C3-C8 aliphatic alcohol is n-butanol. In one embodiment1 the solvent comprises a C6-C18 aromatic hydrocarbon; a C3-C8 aliphatic alcohol; and methanol and/or ethanol1 which acts as an antisolvent for the poly(arylene ether). The C6-C18 aromatic hydrocarbon1 the C3-C8 aliphatic alcohol1 and the methanol or ethanol may be combined in any proportion1 but it may be preferred that the solvent comprise at least about 50 wei8ht percent of the C6-Cl8 aromatic hydrocarbon.
In another embodiment1 the solvent is substantially free of any C1-C6 alkanol. By substantially free1 it is meant that the solvent comprises less than about 0.1 wei8ht percent of a C1-C6 alkanol. In this embodiment1 it is preferred that the solvent comprises no intentionally added C1-C6 alkanol.
The poly(arylene ether) solution is preferably a homo8eneous solution. In other words1 the poly(arylene ether) solution is preferably free of undissolved solid particles1 especially particles havin8 any dimension 8reater than 1 micrometer. In one embodiment1 the poly(arylene ether) solution does not exhibit a cloud point when cooled. For example1 as solutions of poly(216-dimethyl-l14-phenylene ether) in toluene are concentrated1 they may form a 8elatinous phase without the discrete solid particles characteristic of a cloud point. A method of determinin8 the cloud point of a poly(arylene ether) solution (and therefore of determinin8 whether a poly(arylene ether) exhibits such a cloud point) is described in U.S. Patent No. 614441779 to Sin8h etal.
There is no particular limit on the antisolvent employed in the method. Suitable antisolvents include lower alkanols havin8 one to about ten carbon atoms1 such as methanol1 and the like; ketones havin8 three to about ten carbon atoms1 such as acetone1 and the like; and alkanes havin8 five to about ten carbon atoms1 such as hexane; and the like; and combinations thereof. A preferred antisolvent comprises
methanol1 ethanol1 n-propanol1 isopropanol1 n-butanol1 isobutanol1 t-butanol1 or the like1 or a mixture thereof. In one embodiment the antisolvent comprises methanol and at least one C3-C6 alkanol. Suitable C3-C6 alkanols include1 for example1 n-propanol1 isopropanol1 n-butanol1' isobutanol1 t-butanol1 n-pehtanol1 2-methyl-l-butanol1 2-methyl-2-butanol1 3^methyl-l -butanol1 3-methyl-2-butanol1 212-dimethyl-l -propanol (neopentyl alcohol)1 cyclopentanol1 1-hexanol1 2-hexanol1 3-hexahol1 2-methyl-l-pentanol1 2-methyl-2-pentanol1 2-methyl-3-pentanol1 4-methyl-l-pentanol1 4-methyl-2-pentanol1 3-methyl-l-pentanol1 3-methyl-2-pentanol1 3*methyl-3-pentanol1 2-ethyl-1-butanol1 213-dimethyl-l-butanol1 213-dimethyl-2-butanol1 212-dimethyl-l-butanol1 313-dimethyl-l-butanol1 313-dimethyl-2-butanol1 cyclopentylmethanol1 1-methylcyclopentanol1 2-methylcyclopentanol1 3-methylcyclopentanol1 cyclohexanol1 and the like1 and mixtures thereof. In another embodiment1 the antisolvent comprises (a) methanol1 and (b) isopropanol1 n-butanol1 or a mixture thereof. A hi8hly preferred antisolvent comprises methanol.
In another embodiment1 the antisolvent comprises about 60 to 99.8 wei8ht percent methanol1 0.1 to about 30 wei8ht percent toluene1 and 0.1 to about 10 wei8ht percent water. Preferably1 the antisolvent comprises about 70 to about 90 wei8ht methanol1 about 5 to about 30 wei8ht percent toluene1 and about 1 to about 6 wei8ht percent water. More preferably1 the antisolvent comprises about 75 to about 85 wei8ht percent methanol1 about 15 to about 25 wei8ht percent toluene1 and about 1.5 to about 5 wei8ht percent water.
The temperatures of the poly(arylene ether) solution and the antisolvent immediately before they are combined will vary accordin8 to many factors1 includin81 for example1 the poly(arylene ether) composition1 the poly(arylene ether) intrinsic viscosity1 the poly(arylene ether) concentration in the solution1 the solvent type1 the antisolvent type1 and the wei8ht ratio of poly(arylene ether) solution to antisolvent. In one embodiment1 the method comprises combinin8 the poly(arylene ether) at a temperature of about 60 to about 100°C with the antisolvent at a temperature of about 15 to about 60°C. Within these ran8es1 the poly(arylene ether) solution temperature may be at least about 70°C1 or at least about 80°C; and the poly(arylene ether) solution temperature may be up to about 95°C1 or up to about 90°C. Also within these ran8es1 the antisolvent temperature may be at least about 20°C1 or at least about 25°C; and the antisolvent temperature may be up to about 55°C1 or up to about 50°C. The temperature of the combined poly(arylene ether)-antisolvent mixture may preferably be about 30 to about 55°C.
In another embodiment1 the method may1 optionally1 further comprise concentratin8 the poly(arylene ether) solution prior to the combinin8 the poly(arylene ether) solution with the antisolvent. In one embodiment1 concentratin8 the poly(arylene ether) solution is conducted in a continuous process section comprisin8 a heat exchan8er1 a flash unit1 and a circulation pump. Optionally1 part of the concentrated solution product dischar8ed from the flash unit may be recycled to the inlet of the heat exchan8er. In one embodiment1 the flash unit is operated at a pressure less than one atmosphere1 and the temperature of the poly(arylene solution) in the heat exchan8er is 8reater than the boilin8 point of the solvent at the actual pressure in the flash unit. In this embodiment1 the lower pressure in the flash unit results in adiabatic flashin8 of part of the solvent1 Preconcentratin8 the poly(arylene ether) solution may comprise maintainin8 a flash vessel at a pressure1 P1 heatin8 the poly(arylene ether) solution to a temperature1 T1 above the boilin8 point of the solvent at pressure P1 introducin8 the heated poly(arylene ether) solution to the flash vessel to evaporate a portion of the solvent and form a concentrated poly(arylene ether) solution1 and recirculatin8 a portion of the concentrated poly(arylene ether) solution to a point upstream of the flash vessel.
Combinin8 the poly(arylene ether) solution with the antisolvent forms a poly(arylene ether) dispersion. The method may1 optionally1 further comprise separatin8 the poly(arylene ether) solid from the poly(arylene ether) dispersion. In one embodiment1 separatin8 the poly(arylene ether) solid from the poly(arylene ether) dispersion comprises filtration. In another embodiment1 separatin8 the poly(arylene ether) solid from the poly(arylene ether) dispersion comprises centrifu8ation. Suitable filtration apparatuses include rotatin8 filters1 continuous rotary vacuum filters1 continuous movin8 bed filters1 batch filters1 and the like. Suitable solid/liquid separation apparatuses include continuous solid/liquid centrifu8es.
The method allows control of the particle size distribution of the isolated poly(arylene ether) solid. The desired particle size distribution may vary as a function of1 for example1 the poly(arylene ether) composition and intrinsic viscosity. In one embodiment1 the isolated poly(arylene ether) solid has a number-avera8e mean particle size of about 200 micrometers to about 11000 micrometers. Within this ran8e1 the mean particle size may be at least about 300 micrometers. Also within this ran8e1 the mean particle size may be up to about 900 micrometers1 or up to about 800 micrometers1 or up to about 700 micrometers.
The method may1 optionally1 further comprise treatin8 the poly(arylene ether) with a functionalizin8 a8ent comprisin8 (a) at least one carbon-carbon double bond or carbon-carbon triple bond and (b) at least one functional 8roup selected from carboxylic acid1 acid anhydride1 acid amide1 imide1 ester1 amino1 hydroxy1 and the like. Suitable functionalizin8 a8ents include1 for example1 maleic acid1 fumaric acid1 maleic anhydride1 maleimides such as N-phenylmaleimide and 114- phenylene-bis-methylene-a.a'-bismaleimide1 maleic hydrazide1 methylnadic anhydride1 fatty oils (e.8.1 soybean oil1 run8 oil1 linseed oil1 sesame oil)1 unsaturated carboxylic acids such as acrylic acid1 crotonic acid1 methacrylic acid and oleic acid1 unsaturated alcohols such as allyl alcohol and crotyl alcohol1 and unsaturated amines such as allylamine. A preferred functionalizin8 a8ent comprises maleic anhydride. In one embodiment1 the poly(arylene ether) is treated with the functionalizin8 a8ent in solution or slurry prior to precipitation. In another embodiment1 an isolated poly(arylene ether) may be treated with a 8aseous functionalizin8 a8ent. Other functionalizin8 a8ents1 as well as functionalizin8 methods1 are described1 for example1 in U.S. Patent No. 418881397 to van der Meer et al.1 and Japanese Patent Publication No. 2003-183385 to Tokiwa et al.
One embodiment is a method of precipitatin8 a poly(arylene ether)1 comprisin8: combinin8 a poly(arylene ether) solution with an antisolvent to form a poly(arylene ether) dispersion comprisin8 a poly(arylene ether) solid; wherein the antisolvent comprises an alkanol havin8 one to about ten carbon atoms; wherein the poly(arylene ether) solution comprises a poly(arylene ether) and a solvent; wherein the poly(arylene ether) comprises a poly(216-dimethyl-l14-phenylene ether)1 a poly (216-dimethyl-l14-phenylene ether-co-21316-trimethyl-l14-phenylene ether)1 or a mixture thereof; wherein the solvent comprises a C6-C18 aromatic hydrocarbon; and wherein said combinin8 comprises mixin8 with a shear rate of 8reater than 601000 sec"1.
Another embodiment is a method of precipitatin8 a poly(arylene ether)1 comprisin8: combinin8 a poly(arylene ether) solution with an antisolvent to form a poly(arylene ether) dispersion comprisin8 a poly(arylene ether) solid; wherein the antisolvent comprises methanol; wherein the poly(arylene ether) solution comprises a poly(arylene ether) and a solvent; wherein the poly(arylene ether) comprises a poly(216-dimethyl-l14-phenylene ether) havin8 an intrinsic viscosity of about 0.05 to about 0.3 deciliters/8ram at 25°C in chloroform; wherein the solvent comprises toluene; and wherein said combinin8 comprises mixin8 with a shear rate of 8reater than 751000 sec'1.
Another embodiment is a poly(arylene ether) prepared by any of the above methods. In one embodiment1 the isolated poly(arylene ether) comprises less that 10 wei8ht percent1 preferably less than 5 wei8ht percent1 more preferably less than. 2 wei8ht percent1 of particles smaller than 38 micrometers. It will be understood that "smaller
.t
than 38 micrometers" refers to an equivalent spherical diameter less than 38 micrometers. One advanta8e of the invention is that poly(arylene ether) solids prepared by the method exhibit improved flow properties. For example1 the poly(arylene ether) may exhibit a flowability value of about 70 to 100. Within the ran8e of about 70 to 1001 the flowability value may preferably be at least about 751 more preferably at least about 82. Flowability may be determined by measurin8 percent compressibility. Percent compressibility1 %C1 is determined accordin8 to the equation
where PBD is the packed bulk density and ABD is the aerated bulk density. Compressibility may be measured with commercially available instrumentation1 such as1 for example1 a Hosakawa powder testin8 device available from Hosokawa Micron Powder Systems1 10 Chatham Road Summit1 NJ 079011 USA. There is an inverse correlation between percent compressibility values and flowability values1 as shown in Table 11 below. In Table 11 percent compressibility is abbreviated "Comp"1 and flowability is abbreviated "Flow". Thus1 preferred percent compressibility values are 0 to about 201 preferably 0 to about 1 7.51 more preferably 0 to about 14. One embodiment is an apparatus for preparin8 a pdly(arylene ether)1 comprisin8: means for preparin8 a poly(arylene ether) solution comprisin8 a poly(arylene ether) and a solvent; means for combinin8 the poly(arylene ether) solution and an antisolvent at a shear rate of 8reater than 501000 sec'1 to form a poly(arylene ether) dispersion comprisin8 a poly(arylene ether) solid; and means for separatin8 the poly(arylene ether) solid from the poly(arylene ether) dispersion to form an isolated poly(arylene ether) solid. The poly(arylene ether) solution may be prepared by polymerizin8 a monohydric phenol in a solvent. Alternatively1 the poly(arylene ether) solution may be prepared by dissolvin8 a previously isolated poly(arylene ether) in a solvent. FI8. 1 illustrates one embodiment of a poly(arylene ether) isolation apparatus 10. Optional reactor 20 is used to polymerize a monohydric phenol in solvent to form a poly(arylene ether) solution 510. The poly(arylene ether) solution 510 is then concentrated by solvent removal in optional preconcentration unit 30 to form a concentrated poly(arylene ether) solution 520. The preconcentration unit 30 may comprise a heat exchan8er 321 a flash evaporation unit 341 and a recirculation pump 36. Antisolvent 5301 from antisolvent reservoir 401 is combined with the concentrated poly(arylene ether) solution 520 in hi8h-shear mixin8 pump 50 to form poly(arylene ether) dispersion 540. The poly(arylene ether) dispersion 540 is pumped to an optional precipitation tank 60 where it is stirred and released as a8ed poly(arylene ether) dispersion 550. The a8ed poly(arylene ether) dispersion 550 is separated by optional centrifu8e 70 into combined solvent and antisolvent 560 and poly(arylene ether) solid 570. The poly(arylene ether) solid 570 conveyed to optional drier 801 which produces dried poly(arylene ether) solid 580.
The invention is further illustrated by the followin8 non-limitin8 examples. EXAMPLE 11 COMPARATIVE EXAMPLE 1
A solution of 38 wei8ht percent poly(216-dimethyl-l14-phenylene ether) in toluene was prepared. The poly(216-dimethyl-l14-phenylene ether) had an intrinsic viscosity of 0.46 deciliters/8ram in toluene at 25°C. The solution1 at a temperature of 82°C1 was combined with antisolvent consistin8 of 78% methanol1 19% toluene and 3%
water at a temperature of 30°C1 in a volume ratio of 1:51 respectively. For Example 11 the solution and the antisolvent were combined usin8 a hi8h shear pump characterized by a shear rate of 1801000 sec"11 a stator-rotor 8ap width of 0.15 millimeters1 and a circumferential linear velocity of 27 meter/second. For Comparative Example 21 the
.* .
solution and antisolvent were combined in a stirred tank with an a8itator havin8 a rotation rate of 130 rpm and an ener8y input about forty times less than that of the hi8h shear pump of 130. The precipitates thus obtained were filtered1 dried1 and characterized by particle size analysis usin8 a Malvern PSD (particle size distribution) analyzer1 which uses a laser li8ht dispersion technique to determine the wei8ht percent of particles smaller than 38 micrometers. The results1 presented in Table 21 show that the Example 1 precipitate had a substantially lower content of "fines" than did the Comparative Example.
EXAMPLE 21 COMPARATIVE EXAMPLE 2
The procedure of Example 1 and Comparative Example I was repeated1 except that
the intrinsic viscosity of the poly(216-dimethyl-l14-phenylene ether) was 0.40
deciliters/8ram1 and the poly(arylene ether) solution contained 42% of poly(216-
dimethyl-l14-phenylene ether). The results1 presented in Table 31 a8ain show thai
hi8h shear mixin8 produces an isolated poly(arylene ether) havin8 a reduced content
of undesirably small particles.invention has been described with reference to a preferred embodiment1 i will be understood by those skilled in the art that various chan8es may be made an equivalents may be substituted for elements thereof without departin8 from the scopi of the invention. In addition1 many modifications may be made to adapt a particula situation or material to the teachin8s of the invention without departin8 from essentia scope thereof. Therefore1 it is intended that the invention not be limited to th particular embodiment disclosed as the best mode contemplated for carryin8 out
invention1 but that the invention will include all embodiments fallin8 within the scope of the appended claims.
All cited patents1 patent applications1 and other references are incorporated herein by reference in their entirety.

CLAIMS:
1. A method of precipitating a poly(arylene ether), comprising:
combining a poly(arylene ether) solution with an antisolvent to form a poly(arylene ether) dispersion comprising a poly(arylene ether) solid;
wherein the poly(arylene ether) solution comprises a poly(arylene ether) and a solvent; and
wherein said combining comprises mixing with a shear rate of greater than 50,000 sec'1.
2. The method of claim 1, wherein the shear rate is about 60,000 to about
500,000 sec1.
3. The method of claim 1, wherein said combining comprises mixing with
a pump comprising a stator and a rotor.
4. The method of claim 3, wherein the stator and the rotor define a gap
width of about 0.01 to about 1 millimeter.
5. The method of claim 3, wherein the rotor has a circumferential linear
velocity of about 1 to about 100 meters per second.
6. The method of claim 1, wherein said combining is characterized by a
volume ratio of the poly(arylene ether) solution to the antisolvent of about 1:1 to
about 1:10.
7. The method of claim 1, wherein said combining comprises combining
the poly(arylene ether) solution at a temperature of about 70 to about 100 °C with the
antisolvent at a temperature of about 15 to about 60°C.
8. The method of claim 1, wherein the poly(arylene ether) solution
comprises about 10 to about 70 weight percent of the poly(arylene ether), based on the
total weight of the poly(arylene ether) solution.
9. The method of claim 1, wherein the poly(arylene ether) solution does
not exhibit a cloud point.
reconcentrating the poly(arylene ether) solution.