CA2077846A1 - Method for preparing reactive chlorotriazine-capped polyphenylene ethers employing short reaction time - Google Patents

Abstract

METHOD FOR PREPARING REACTIVE
CHLOROTRIAZINE-CAPPED
POLYPHENYLENE ETHERS EMPLOYING
SHORT REACTION TIME

Abstract Reactive triazine-capped polyphenylene ethers are pre-pared by the reaction of an alkaline polyphenylene ether mixture with a reactive chlorotriazine employing a contact time up to about 15 minutes, most often up to about 5 minutes and preferably up to about 1 minute. The reaction may be conducted semi-continuously or continuously. The product is characterized by a larger average par-ticle size than when a longer reaction time is employed.

Description

METI~OD FOR PR~PARING ~EACTIVE
CHLOROTRIAZINE-CAPPED
POLYPHENYlEN~ ETHER~ EMPLOYIN~;
~HORT REA~TION TIME

This invention relates to the capping of polyphenylene ethers with reactive chlorotriazines, and more particularly to an improved method for such capping which yields a product having improved properties.
The capping of polyphenylene ethers by reaction with re-active chlorotriazines has previously besn disclosed. The capped polyphenylene ethers thus obtained are capable of undergoing reac-tion with other polymers containing reactivs groups such as amine or carboxy groups, to form copolymer-containing compositions which serve as compatibilizers for blends of otherwise incompatible polymers. Among the reactive chlorotriazines which may be em-ployed are those containing epoxy groups and those containing halo or dialkylphosphato moieties, respectively disclosed in copsnding, commonly owned applications Serial Nos. 07/351,905 and 07/653,586.
The previously disclosed methods for preparation of re-active triazine-capped polyphenylene ethers involve batch reactions in solution in a substantially inert organic liquid such as toluene, and in the presence of water and an alkaline reagent. A phase trans-fer catalyst is normally employed to maximize contact between the water-soluble and organic-soluble molecular species. Such reactions are ordinarily conducted in simple batch reactors of the stirred-tank type. Following completion of the reaction, the product is typically precipitated from the organic solution by adding a non-solvent such as methanol and filterin~.
Reaction times shorter than about 30 minutes are gen-erally impractical for such processes. Even in the case of chemical reactions for which a shorter reaction time is desired and the pro-cess parameters are adjusted for that purpose, the effective reac-tion time will include the period during which at least a part of the mixture remains in the tank reactor while it awaits transfer to the precipitation apparatus. As a result, overall contact times are al-most always 30 minutes or longer; and, in fact, the times disclosed in the aforementioned applications for the capping of polyphenylene ethers are at least 30 minutes.
The products prepared by these previously described methods are satisfactory in most respects. However, it is frequently found that precipitation of products prepared on a large scale yields a material with a substantial proportion of very small particles, hereinafter sometimes designated ~fines~. These can clog filters and sometimes even constitute an explosion hazard. Moreover, products with a large particle size distribution including a substantial pro-portion of fines are difficult to process in many melt processing operations, particularly eompounding extruders, since they tend to bridge and clog feeder hoppers employed in combination with such extruders. It is therefore desirable to modify the process for cap~
ping polyphenylene ethers with reactive ehlorotriazines, so as to obtain a produet having a relatively narrow partiele size distribu-tion and no si~nifieant fines eontent, By the present invention, the proportion of fines in the reaetive triazine~eapped polyphenylene ether is substantially de-ereased. Therefore, the produet obtained has the desired relatively large partiele size and is easy to handle. Moreover, the process is adaptable to semi-eontinuous or eontinuous operation, whereby the desired produet may be obtained eonveniently and in high yield in a relatively short time.
The invention is based on the diseovery that the propor-tion of fines in the eapped polyphenylene ether product increases substantially with an inerease in eontaet time between the polyphenylene ether and the reaetive ehlorotriazine, While the pre-sent invention is not dependent upon any partieular theory, it is be-lieved that long eontaet times inerease the probability of the oeeur-rence of relatively slow side reaetions whieh involve reaetive 20778~6 groups on the polyphenylene ether chain and/or form species capable of changing the ionic strength of the aqueous phase, thus affecting the precipitation characteristics of the product. Inoreased propor-tions of fines are particularly noticeable with contact times longer than about 30 minutes, but are also a factor at shorter contact times. It has been discovered that the desired reaction can be made to go essentially to completion in a period no longer than about 60 seconds, thus eliminating the need for longer reaction times and facilitating the formation of a product having the desired particle size characteristics.
Accordingly, the invention is a method for preparing a reactive triazine-capped polyphenylene ether which comprises the steps of:
contacting a solution of a polyphenylene ether in a sub-stantially non-polar organic liquid with at least one alkaline reagent, to form an alkaline polyphenylene ether mixture:
subsequently contacting said mixture for a time period up to about 15 minutes with at least one chlorotriazine containing reactive ~roups, said contact being effected in the presence of wa-ter and a reaction-promoting amount of a phase transfer catalyst, to produce a solution of said capped polyphenylene ether in said organic liquid, and recoverin~ said capped polyphenylene ether.
The drawings are schematic depictions of two forms of apparatus in which the method of the invention may be advanta-geously performed. FIGURE 1 shows a semi-continuous and FIGURE 2 a continuous apparatus.
The polyphenylene ethers employed in the method of this invention are known polymers comprising a plurality of structural units of the formula 20778~6 (I) o<O~ .

Q~\ Q~
In each of said units independently, each Q1 is independently halo-gen, primary or secondary lower alkyl (i.e., alkyl containing up to 7 carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Q2 is independsntly hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydro-carbonoxy or halohydrocarbonoxy as defined for Q1. Most often, each Q1 is alkyl or phenyl, especially C1.4 alkyl, and each Q2 is hydrogen.
Both homopolymer and copolymer polyphenylene ethers are included. The preferred homopolymers are those containing 2,6-dimethyl-1,4-phenylene ether units. Suitable copolymars include random copolymers containing such units in combination with (for example) 2,3,6-trimethyl-1,4-phenylene ether units. Also included are polyphenylene ethers containing moieties prepared by grafting onto the polyphenylene ether in known manner such materials as vinyl monomers or polymers such as polystyrenes and elastomers, as well as coupled polyphenylene ethers in which coupling agents such as low molecular weight polycarbonates, quinones, heterocycles and formals undergo reaction in known manner with the hydroxy groups of two polyphenylene ether chains to produce a higher molecular weight polymer, provided a substantial proportion of free OH groups remains.
The polyphenylene ether generally has a number average molecular weight within the range of about 3,000-40,000 and a weight average molecular weight within the range of about 20,000-80,000, as determined by gel permeation chromatography Its in-trinsic viscosity is most often in the range of about 0.15-0.6 dl./g., as measured in chloroform at 25C.

The polyphenylene ethers are typically prepared by the oxidative coupling of at least one monohydroxyaromatic compound such as 2,6-xylenol or 2,3,6-trimethylphenol. Catalyst systems are generally employed for such coupling; they typically contain at least one heavy metal compound such as a copper, manganese or cobalt compound, usually in combination with various other materials.
Particularly useful polyphenylene ethers for many pur-poses are those which comprise molecules having at least one aminoalkyl-containing end group. The aminoalkyl radical is typically located in an ortho position to the hydroxy group. Products contain-ing such end groups may be obtained by incorporating an appropriate primary or secondary monoamine such as di-n-butylamine or dimethylamine as one of the constituents of the oxidative coupling reaction mixture. Also frequently present are 4-hydroxybiphenyl end groups, typically obtained from reaction mixtures in which a by-product diphenoquinone is present, especially in a copper-halide-secondary or tertiary amine system.
A substantial proportion of the polymer molecules, typi-cally constituting as much as about 90% by weight of the polymer, may contain at least one of said aminoalkyl-containing and 4-hydroxybiphenyl end groups. For the purpose of the present invention, however, it is essential that a substantial proportion of the end ~roups have the formula Q~ a' (Il) ~a~ ~
Q~\ Q1 which may be directly anached to oxygen (i.e., ordinary polypheny-lene ether non-aminoalkyl-containing head end groups) or to another phenyl ring (i.e., 4-hydroxybiphenyl tail end groups).

20778~6 It will be apparent to those skilled in the art from the foregoing that the polyphenylene ethers contemplated for use in the present invention include all those presently known, irrespective of variations in structural units or ancillary chemical features.
A wide variety of chlorotriazines containing reactive groups may be employed in the method of the invention. They include compounds of the formula Cl (111) NlN
X1zJ~NJ\ac2 wherein x1 is an alkyl, cycloalkyl or aromatic radical or Rl-X3, x2 is an aromatic radical or R1-X3, R1 is a C1 4 alkylene radical which is unsubstituted or contains substituents inert to displacement by nu-cleophilic moieties, X3 is a group capable of reaction with nucleo- -philic moieties and Z is oxygen or sulfur. Most often, X2 is a glycidyl group or a group having the formula (R2)3-n ~ R4 (IV) ~ (R3)m C X4 ~4 n wherein X4 iS a group displaceable by nucleophilic substitution, most often chlorine, bromine or dialkylphosphato; each R2 is inde-pendently hydrogen, C1.4 primary or secondary alkyl or a non-hydro-carbon substituent substantially inert to displacement by nucleo-philic moieties; R3 is a C1.3 alkylene radical which is unsubstituted or is substituted with moieties selected from the group consistin~
of C1.4 primary and secondary alkyl radicals and non-hydrocarbon 2077g-46 substituents as defined for R2; each R4 is independently R2 or X4; m is O or 1 and n is 1-3. Still more preferabiy, X4 has the formula (V) -Z-P(ZR5)2 wherein Z is as previously defined and each Rs is a C1 30 primary or secondary alkyl, cycloalkyl, aromatic or aralkyl radical or both R5 radicals together with the P and Z atoms form a cyclic structure.
Illustrative of the chlorotriazines which may be em-ployed in the present invention are:

2-chlero-4,6-diphenoxy-1 ,3,5-triazine, 2-chloro-4,6-bis(2,4 ,6-trimethylphenoxy)-1 ,3,5-tri-azine, 2-chloro-4,6-diglycidoxy-1 ,3 ,5-triazine, 2-chloro-4-(n-butoxy)-6-glycidoxy-1 ,3,5-triazine, 2-chloro-4-(2,4,6-trimethylphenoxy)-6-glycidoxy-1,3,5-triazine (hereinafter "MGCC7, 2-chloro-4-(2,4,6-trimethylphenoxy)-6-(2-chloroethoxy)-1 ,3,5~triazine, 2-chloro-4-(2,4,6-trimethylphenoxy)-6-(2-bromo-ethoxy)-1 ,3 ,5-triazine, 2-chloro-4-(2,4,6-trimethylphenoxy)-6-(2-diethylphos-phatoethoxy)-1 ,3 ,5-triazine, 2-chloro-4-(2,4,6-trimethylphenoxy)-6-(2-di-n-butylphosphatoethoxy)-1,3,5-triazine, and 2-chloro-4-(2,6-xylenoxy)-6-(2-di-n-butylphos-phatoethoxy)-1 ,3 ,5-triazine.
Such compounds may be prepared by the reaction of cyanuric chloride (i.e, 2,4,6-trichlorotriazine) with the hydroxy or thio compound(s) corresponding to the substituent(s) on the heterocyclic ring.
Also employed in the method of this invention are water, a substantially non-polar organic liquid, a phase transfer catalyst and at least one alkaline reagent. Suitable organic liquids include chlorinated aliphatic hydrocarbons such as chloroform; aromatic hydrocarbons such as toluene and xylene; and chlorinated aromatic hydrocarbons such as chlorobenzene and o-dichlorobenzene. The aro-matic hydrocarbons and especially toluene are usually preferred.
Any phase transfer catalyst which is stable and effec-tive under the prevailing reaction conditions may be used; those skilled in the art will readily perceive which ones are suitable.
Particularly preferred are the tetraalkylammonium chlorid0s wherein at least two alkyl groups per molecule, preferably two or three, contain about 4-20 carbon atoms.
The alkaline reagent may be inorganic, as illustrated by sodium hydroxide and potassium hydroxide; organic, as illustrated by various amines including pyridine and dimethyl-n-butylamine (hereinafter "DMBA~); or a mixture of inorganic and organic reagents.
Alkali metal hydroxides ars often employed, with sodium hydroxide being the especially preferred alkali metal hydroxide by reason of its availability and particular suitability. It is often advantageous to employ a trialkylamine such as DMBA by reason of its common presence in catalyst systems employed for the preparation of polyphenylene ethers; it may be employed as the only alkaline reagent or in combination with an alkali metal hydroxide.
According to the present invention, the polyphenylene ether solution in the or~anic liquid is first contacted with the alka-line reagent or reagents, to form an alkaline polyphenylene ether mixture. There may also be present at this stage the water (especially when the alkaline reagent is an alkali metal hydroxide) and the phase transfer catalyst, although it is within the scope of the invention to introduce these materials at a later sta~e.
The period of contact with the alkaline reagent is an ef-fective period for formation of the alkaline polyphenylene ether mixture. When an amine is the only alkaline reagent employed, this generally will not involve salt formation and the contact time may be limited to the time required for mixing. When an aqueous base is employed, a contact time of about 20-200 minutes is typical.

2077~46 Subsequently, contact is initiated between the alkaline polyphenylene ether mixture and the reactive chlorotriazine, and is maintained for a period up to about 15 minutes. It has been estab-lished that this period is adequate for the capping reaction to go es-sentially to completion, and also facilitates the formation of a product with a relatively large particle size and the absence of fines in deleterious amounts. The contact period is most often up to about 5 minutes and preferably up to about 1 minute.
By reason of the short contact times required, the method of this invention is particularly suitable for continuous or semi-continuous operation. The term ~semi-continuous", as used herein, denotes a proeess in which early stages are performed batchwise and later stages eontinuously. Thus, the first portion of sueh a reaetion may be conducted in a stirred tank or similar vessel, the contents of which are then transferred to a continuous reactor for further stages.
Upon completion of the contaet time between the alka-line polyphenylene ether mixture and the reactive chlorotriazine, the eapped polyphenylene ether obtained as produet is recovered.
Reeovery may be aehieved eonventionally, a suitable method being preeipitation with a non-solvent for the polyphenylene ether sueh as methanol, aeetone, aeetonitrile or eombinations thereof.
In the drawings, there are shown two illustrative eon-figurations of equipment whieh may be employed for the sem-eon-tinuous and eontinuous modes of the method of this invention.
FIGURE 1 illustrates an apparatus for semi-eontinuous operation; it ineludes tank reaetor 1 of suitable size to hold an initial blend of polyphenylene ether, phase transfer eatalyst, alkaline reagent and solvent in the desired quantities. Reaetor 1 as shown in FIGURE 1 is typieally a stirred bateh reaetor of conventional design.
Reaetor 1 is eharged at 3 with a solution of polypheny-lene ether in organie solvent, which may be a "body feed" solution whieh is the product of polymerization by oxidative coupling of a monohydroxyaromatie eompound sueh as 2,6-xylenol. Also charged to 207i846 the tank reactor are a phase transfer catalyst at 5 and water and an alkaline reagent at 7.
The reaction m.xture in reactor 1 is suitably agitated by means of a conventional agitator (not shown) for a period of time sufficient to provide adequate mixing and result in formation of the alkaline polyphenylene ether mixture. Said mixture is then trans-ferred to line 9 by the action of pump 11. At the same time, a reac-tive chlorotriazine such as MGCC (optionally in combination with water, especially if none was introduced earlier), present in vessel 13, is pumped via pump 15 through line 17, and is combined with the polyphenylene ether mixture at 19. Continued action of pump 11 causes the reaction mixture to pass into continuous reactor 21, of suitable size to provide the desired contact time between the polyphenylene ether and the reactive chlorotriazine.
Reactor 21 may be a small continuous stirred-tank reac-tor (hereinafter ~CSTR~), but is most often a plug flow reactor. The term "plug flow~, as used herein, is defined as in Levenspiel, Chemical Reaction Engineering, Second Edition, p. 97:
It is characterized by the fact that the flow of fluid through the reactor is orderly with no ele-ment of tluid overtaking or mixing with any other element ahead or behind. Actually, there may be lateral mixing of fluid in a plug flow reactor; how-ever, there must be no mixing or diffusion along the flow path.

Suitable plug flow reactors include simple tube reactors, baffled re-actors and other plug flow reactors of the type known in the an.
Atter a suitable residence time, up to about 15 minutes, in reactor 21, the mixture including the desired capped polyphenylene ether solution exits at 23 and the capped polyphenylene ether is recovered therefrom, typically by precipitation with a non-solvent.
An apparatus suitable for fully continuous capping is shown in FIGURE 2, which in part employs the same reference num-20778~6 bers as FIGURE 1. Polyphenylene ether solution passes through line 10. Alkaline reagent present in vessel 4 is transferred via pump 12 through line 14, meeting the polyphenylene ether mixture at 16. The combined stream then passes into reaetor 1 which, in this case, is usually a CSTR although a plug flow reactor may be employed. Phase transfer catalyst is introduced at 18 into reactor 1. After a contact time in reaetor 1 effective for formation of the alkaline polypheny-lene ether mixture, said mixture is transferred via line 9 to contact with the reactive ehlorotriazine as previously deseribed and form the eapped polyphenylene ether solution, from whieh the desired produet may be recovered.
The proportions of reagents employed in the method of this invention are generally eonventional for reaetions between re-aetive ehlorotriazines and polyphenylene ethers. Thus, a molar ratio of alkaline reagent to polyphenylene ether of about 1.0-3.5:1 may be employed. Phase transfer eatalyst may be present in the amount of about 0.1-10.0% and preferably about 0.5-2.0 % by weight, based on polyphenylene ether, and wabr in the amount of about 0.5-50.0 % and preferably about 2-30%, also based on polyphenylene ether. The amount of organie liquid is not eritieal but is most often about 2-3 ml. p~r gram of polyphenylene ether. Reaetion temperatures in the range of about 20-100C are typieal.
A partieularly advantageous feature of the method of this invention, espeeially in the semi-eontinuous and eontinuous em-bodiments deseribed hereinabove, is the redueed quantity of reactive ehlorotriazine which may be employed. Whereas previous methods often required a substantial exeess, typically at least about 1.5 moles per mole of polyphenylene ether and sometimes even more, the present invention affords eapped polyphenylene ether in high yields when the molar ratio of reaetive ehlorotriazine to polyphenylene ether is as low as 1:1. Most often, molar ratios in the range of about 1.0-1.2:1 are advantageously employed.
The method of this invention is illustrated by the fol-lowing examples. The reagents employed were MGCC, DMBA, sodium hydroxide and, as a phase transfer catalyst, a commercially avail-able methyltrialkylammonium chloride in which the alkyl groups contained 8-10 carbon atoms. Two different poly(2,6-dimethyl-1,4-phenylene ethers) were employed, both having an intrinsic viscosity in chloroform at 25C of 0.40 dl./g. All percentages are by weight.
Reagent percentages are based on polyphenylene ether, and molar ratios and OH percentages are based on non-hydrogen bonded OH end ~roups in the polyphenylene ether.

Example 1 A number of experiments were run to determine the ef-fect of contact time on the particle size of the capped polyphenylene ether obtained as product. The polyphenylene ether employed had a hydroxy end group concentration of 0.1%, a substantial proportion of which was in the form of end groups of formula ll.
In these experiments, DMBA in a molar ratio of 5:1 and phase transfer catalyst in the amount of 1% were added to a 25%
solution of polyphenylene ether in toluene at 65C. An aqueous solu-tion ot sodium hydroxide (3:1 molar ratio of sodium hydroxide, water volume 8% of polyphenylene ether solution) was added and the mix-ture was stirred for 20 minutes, after which MGCC in a molar ratio of 2,5:1 was added.
Stirring of the reaction mixture was continued and sam-ples were removed periodically and precipitated in a hi~h-speed blender with a mixture of 35 parts (by weight) toluene, 65 parts methanol and 4 parts water, The products were dried and suspended in methanol at a concentration of 0,1%, and the turbidities of the suspensions were measured using a Horiba Capa particle size ana-lyzer. Turbidity values (on an empirical scale) under 0,4 were ob-tained up to a residence time of about 30 minutes, The turbidity then increased to about 0.53 at 120 minutes and 1.2 at 850 minutes. The turbidity of a control, constituting a solution of polyphenylene ether in toluene with water added in the same proportions as in the reac-tion mixture, remained essentially constant at 0.4 or less for over 500 minutes.
It is apparent from these results that the proportion of fines in the product remains relatively constant at contact times less than 30 minutes, after which it increases substantially.

Example 2 To a solution in reactor 1 (FIGURE 1) of 125 grams of polyphenylene ether having a hydroxy end group concentration of 0.168% in 375 grams of toluene were added, with stirring, 1.25 grams of phase transfer catalyst and 1.5 grams of DMBA. The tem-perature of the solution was stabilized at 60C over 5 minutes, af-ter which 10 grams of an aqueous sodium hydroxide solution (sodium hydroxide molar ratio 1.5:1) was added and stirring was continued for 20 minutes.
At this point, pump 11 was started at a rate to pump the contents of reaetor 1 into line 9 at 43 ~rams per minute. Pump 15 simultaneously pumped a 17.8% solution of MGCC in toluene into the system at 1.5 grams per minute, whieh provided about 1 equivalent per minute of MGCC. Flow was eontinued at this rate for about 2 minutes until steady state was reached, after which the MGCC flow was deereased several times and finally inereased. Under these eonditions, the residenee time of the reaetion mixture in plug flow reactor 21 was about 10 seconds.
Samples of the reaetive epoxytriazine-capped polyphenylene ether were preeipitated by adding aeetonitrile and dried. The eapping level was determined by proton nuclear magnetic resonanee speetroseopy at various times during the run.
The results are ~iven in the following table. Times were determined starting with the assumed attainment of steady state after 2 minutes.

207784~

Time, min. MGCC molar ratio Conversion, %
1 5 1 .1 5 97 2.6 1 .06 9 8 4.2 0.81 8 5 7.3 0.67 7 0 9.2 1.12 90 It is apparent that very high conversions to capped polyphenylene ether are attainable even at a polyphenylene ether-MGCC contact time of only 10 seconds, provided the molar ratio of MGCC to polyphenylene ether is in the range of 1.0-1.2. Similar runs employing other proportions of reagents demonstrated that essen-tially quantitative conversion can be achieved with a DMBA propor-tion as low as 0.15% and a phase transfer catalyst proportion as low as 0.3%.

Example 3 The apparatus of Figure 2 was employed, except that phase transfer catalyst was introduced into vessel 2 instead of re-actor 1. The polyphenylene ethar reactant had a hydroxy end group concentration of 0.1%.
For each run, 500 grams of a 25% solution of polypheny-lene ether in toluene was employed and phase transfer catalyst and DMBA were added at 0.3% and 0.2%, respectively. The MGCC flow from vessel 13 was maintained at a molar ratio of 1.1:1 and the sodium hydroxide flow from vessel 4 at 1.5:1, with the aqueous phase of the caustic solution constituting about 8% by volume of the polyphenylene ether solution. Under the conditions employed, the residence time in plug flow reactor 21 was about 30 seconds.
Two runs each were made at residence times in reactor 1 of 30 seconds and 100 seconds. The average conversions at these two residence times were 87% and 92%, respectively. By extrapola-tion, it was determined that a residence time in reactor 1 of about 3 minutes would be required to reach 100% conversion.

Claims (19)

1. A method for preparing a reactive triazine-capped polyphenylene ether which comprises the steps of:
contacting a solution of a polyphenylene ether in a sub-stantially non-polar organic liquid with at least one alkaline reagent, to form an alkaline polyphenylene ether mixture:
subsequently contacting said mixture for a time period up to about 15 minutes with at least one chlorotriazine containing reactive groups, said contact being effected in the presence of wa-ter and a reaction-promoting amount of a phase transfer catalyst, to produce a solution of said capped polyphenylene ether in said organic liquid, and recovering said capped polyphenylene ether.

2. A method according to claim 1 wherein the polypheny-lene ether is a poly(2,6-dimethyl-1,4-phenylene ether).

3. A method according to claim 2 wherein the contact time between the chlorotriazine and the polyphenylene ether is up to about 5 minutes.

4, A method according to claim 3 wherein the reactive triazine has the formula (III) wherein X1 is an alkyl, cycloalkyl or aromatic radical or R1-X3, X2 is an aromatic radical or R1-X3, R1 is a C1-4 alkylene radical which is unsubstituted or contains substituents inert to displacement by nu-cleophilic moieties, X3 is a group capable of reaction with nucleo-philic moieties and Z is oxygen or sulfur.

5. A method according to claim 4 wherein Z is oxygen.

6. A method according to claim 5 wherein X2 has the for-mula (IV) wherein X4 is a group displaceable by nucleophilic substitution; each R2 is independently hydrogen, C1-4 primary or secondary alkyl or a non-hydrocarbon substituent substantially inert to displacement by nucleophilic moieties; R3 is a C1-3 alkylene radical which is un-substituted or is substituted with moieties selected from the group consisting of C1-4 primary and secondary alkyl radicals and non-hydrocarbon substituents as defined for R2; each R4 is independently R2 or X4; m is 0 or 1 and n is 1-3.

7. A method according to claim 6 wherein X4 is (V) , wherein each R5 is a C1-30 primary or secondary alkyl, cycloalkyl, aromatic or aralkyl radical or both R5 radicals together with the P
and O atoms form a cyclic structure.

8. A method according to claim 7 wherein the reactive chlorotriazine is 2-choro-4-(2,4,6-trimethylphenoxy)-6-glycidoxy-1,3,5-triazine or 2-chloro-4-(2,4,6-trimethylphenoxy)-6-(2-di-n-butylphosphatoethoxy)-1,3,5-triazine.

9. A method according to claim 3 wherein the alkaline reagent is sodium hydroxide, dimethyl-n-butylamine or a mixture thereof.

10. A method according to claim 3 wherein the organic liquid is an aromatic hydrocarbon.

11. A method according to claim 10 wherein the aromatic hydrocarbon is toluene.

12. A method according to claim 3 wherein contact be-tween the polyphenylene ether and the chlorotriazine is conducted continuously.

13. A method according to claim 12 wherein contact between the polyphenylene ether and the chlorotriazine is conducted under plug flow conditions.

14. A method according to claim 13 wherein contact between the polyphenylene ether and the chlorotriazine is conducted in a tube reactor.

15. A method according to claim 13 wherein the alkaline polyphenylene ether mixture is formed batchwise.

16. A method according to claim 15 wherein the resi-dence time in the tube reactor is up to about 1 minute.

17. A method according to claim 13 wherein the alkaline polyphenylene ether mixture is formed continuously.

18. A method according to claim 17 wherein the resi-dence time in the tube reactor is up to about 1 minute.

19. The invention as defined in any of the proceding claims including any further features of novelty disclosed.