Process for the preparation of poly(aryl ether ketones).

0001The invention relates to a process for the preparation of polyaryl ether ketones by reacting aromatic dihydroxy compounds with aromatic dihalogen compounds in polar aprotic solvents in the presence of alkali metal carbonates.

0002Preferred embodiments of the method according to the invention can be found in the subclaims.

0003EP-A-1 879 describes a process for the preparation of polyaryl ether ketones with repeating units<chemistry id="chem0001" num="0001"><img file="EP0275035A2_D0001.tif" /></chemistry> known by reacting hydroquinone with 4,4'-difluorobenzophenone. This method has the disadvantage that large amounts of the expensive monomer 4,4'-difluorobenzophenone are required.

0004It was therefore an object of the present invention to provide a process for the preparation of polyaryl ether ketones which enables polyaryl ether ketones to be produced more cost-effectively without having to accept a deterioration in the properties of the products. In addition, the amount of fluorine-containing monomers required in the process should generally be reduced.

0005This object is achieved according to the invention by a process of the type defined in the introduction, which is characterized in that aromatic dihydroxy compounds of the general formula I<chemistry id="chem0002" num="0002"><img file="EP0275035A2_D0002.tif" /></chemistry> or their core-substituted C₁-C₈-alkyl, C₁-C₈-alkoxy, aryl, chlorine or fluorine derivatives, where n and m are 0 or 1, with aromatic dihalogen compounds of the general formula II<chemistry id="chem0003" num="0003"><img file="EP0275035A2_D0003.tif" /></chemistry> or their core-substituted C₁-C₈-alkyl, C₁-C₈-alkoxy, aryl, chlorine or fluorine derivatives, where r and s each have the value 0 or 1, A is an oxygen atom or a chemical bond and X is chlorine or fluorine is implemented.

0006An advantage of the process according to the invention over the process known, for example, from EP-A-1 879 is that the use of the dihydroxy compounds of the general formula I, which have higher molecular weights compared to the monomers normally used, increases the proportion of dihalogen compounds, in particular Difluorverbindungen can be reduced. This is illustrated by the following example, which relates to the production of PEEK (poly (ether ether ketone)):<chemistry id="chem0004" num="0004"><img file="EP0275035A2_D0004.tif" /></chemistry>

0007This shows that in the process according to the invention, when using the same amount of 4,4'-difluorobenzophenone, by using the dihydroxy compounds of the general formula I, twice the amount of product can be produced than in the conventional process. Corresponding calculations can also be made for other polyaryl ether ketones known per se, for example for the production of PEEKK (E stands for ether bridges, K for keto bridges in the polymer).

0008The compounds fall under the general formula I.<chemistry id="chem0005" num="0005"><img file="EP0275035A2_D0005.tif" /></chemistry> 1,4-di- [4- (4-hydroxyphenoxy) benzoyl] benzene (m = 1, n = 0)<chemistry id="chem0006" num="0006"><img file="EP0275035A2_D0006.tif" /></chemistry> 4,4ʹ-di (4-hydroxyphenoxy) benzophenone (m = 0, n = 0) and<chemistry id="chem0007" num="0007"><img file="EP0275035A2_D0007.tif" /></chemistry> 4,4ʹ-di [4- (4-hydroxyphenoxy) benzoyl] diphenyl (m = 1, n = 1) as well as their core-substituted C₁-C₈-alkyl, C₁-C₈-alkoxy, aryl, chlorine or fluorine derivatives. Examples of substituents are methyl, ethyl, n-, i- and t-butyl, the corresponding alkoxy groups and phenyl groups. As a rule, however, the unsubstituted compounds Ia-Ic are preferably used.

0009Ia can be prepared, for example, by reacting 1,4-di (4-chlorobenzoyl) benzene with an alkali metal salt of hydroquinone mono-t-butyl ether and subsequent cleavage of the t-butyl ether according to the following reaction scheme:<chemistry id="chem0008" num="0008"><img file="EP0275035A2_D0008.tif" /></chemistry>

0010The compounds Ib and Ic can be obtained in an analogous manner if, instead of 1,4-di- (4-chlorobenzoyl) benzene, 4,4′-dichlorobenzophenone or 4,4′-di (4-chlorobenzoyl) diphenyl is used.

0011The conditions under which such reactions are carried out are generally known, so that further details are not necessary here.

0012The aromatic dihalogen compounds II in the process of the invention are preferably the fluorine compounds 4,4ʹ-difluorobenzophenone<chemistry id="chem0009" num="0009"><img file="EP0275035A2_D0009.tif" /></chemistry> 1,4-di- (4-fluorobenzoyl) benzene<chemistry id="chem0010" num="0010"><img file="EP0275035A2_D0010.tif" /></chemistry> 4,4ʹ-di- (4-fluorobenzoyl) diphenyl ether<chemistry id="chem0011" num="0011"><img file="EP0275035A2_D0011.tif" /></chemistry> and 1,10-di (4-fluorobenzoyl) diphenyl<chemistry id="chem0012" num="0012"><img file="EP0275035A2_D0012.tif" /></chemistry> used. In principle, the chlorine compounds or both chlorine and fluorine-containing compounds can also be used, but the fluorine compounds are preferred. With regard to preferred substituents on the aromatic ring, reference is made here to the corresponding statements regarding the dihydroxy compounds. As there, the unsubstituted compounds IIa to IIc are preferred.

0013If the products obtainable by the process according to the invention by reacting the unsubstituted compounds of the general formulas I and II are compiled in a scheme, the following picture results:<tables id="tabl0001" num="0001"><img file="EP0275035A2_D0013.tif" /></tables>

0014The products are named according to the usual nomenclature, in which E stands for an ether bridge between two aromatic rings and K for a -CO bridge.<chemistry id="chem0013" num="0013"><img file="EP0275035A2_D0014.tif" /></chemistry>

0015In the products marked with *, the hyphen indicates that there is a diphenyl residue between the corresponding bridges.

0016The process according to the invention is carried out in polar aprotic solvents in the presence of alkali metal carbonates as bases. The process conditions such as temperatures, pressure, solvents and any additives (catalysts) are the same as those described, for example, in EP-A-1879. Accordingly, solvents of the formula are suitable<chemistry id="chem0014" num="0014"><img file="EP0275035A2_D0015.tif" /></chemistry> in which Y is a chemical bond, an oxygen atom or two hydrogen atoms bonded to the aromatic radicals, and Z and Zʹ are hydrogen or phenyl groups.

0017A particularly preferred process variant is the reaction in diphenyl sulfone as the solvent in the presence of anhydrous potassium carbonate as the base.

0018The amount of diphenyl sulfone is generally 5 to 100 mol, preferably 5 to 20 mol, based on 1 mol of monomers. This gives a preferred solids content of the solution in the range from 5 to 50% by weight, particularly preferably from 10 to 40% by weight.

0019Activated monohalogen and / or mononitro compounds, eg<chemistry id="chem0015" num="0015"><img file="EP0275035A2_D0016.tif" /></chemistry> or corresponding monohydroxy compounds can be used.

0020The water formed during the polycondensation can be removed with the aid of an azeotrope, by applying a reduced pressure or, preferably, by introducing a stream of nitrogen and distilling it off.

0021Suitable azeotroping agents are all compounds which boil at normal pressure in the range of the reaction temperature and which can be mixed homogeneously with the reaction mixture without undergoing chemical reactions.

0022The reaction temperature is generally in the range from 150 to 400 ° C., preferably 250 to 350 ° C., the lower temperature limit being determined by the solubility of the product formed in the solvent system; the total reaction time depends on the desired degree of condensation, but is generally in the range from 0.5 to 15 hours.

0023Following the polycondensation, free phenolate end groups can be reacted with an aryl or alkylating agent, for example methyl chloride, for stabilization. This is preferably done at temperatures up to 350 ° C, the lower temperature limit depends on the solubility of the reaction products in the solvent used.

0024The reaction products can be worked up by customary processes known per se. A finely divided material is advantageously produced from the melt and is freed from the high-boiling solvent used by extraction with suitable solvents, for example acetone. Residues of alkali metal carbonate and alkali metal halides can then be removed by washing with water.

0025By appropriate variation when using several dihydroxy or dihalogen compounds, copolycondensates (copolyaryl ether ketones) can also be produced by the process according to the invention.

0026A statistical structure is increased by the simultaneous addition of all monomers, while block copolycondensates are formed when successively adding different dihydroxy or dihalogen compounds. In addition, it is also possible to link blocks produced by the process according to the invention to products with a higher molecular weight.

0027The molecular weight (weight average) of the polyaryl ether ketones obtained by the process according to the invention is generally in the range from 10,000 to 150,000, preferably from 15,000 to 100,000 and in particular from 18,000 to 80,000.

0028If the repeating units are arranged in blocks, the molecular weight of the individual blocks is generally in the range from 500 to 15,000, in particular from 1,500 to 10,000.

0029The polyaryl ether ketones obtained can be mixed with fillers, pigments and other processing aids.

0030As reinforcing fillers, for example, asbestos, carbon fibers and preferably glass fibers may be mentioned, the glass fibers, for example in the form of glass fabrics, mats, nonwovens and / or preferably glass silk rovings or cut glass silk made from low-alkali E-glasses with a diameter of 5 to 20 μm, preferably 8 to 15 μm are used, which after incorporation have an average length of 0.05 to 1 mm, preferably 0.1 to 0.5 mm. The polyaryl ether ketones reinforced with glass silk rovings or cut glass silk contain between 10 and 60% by weight, preferably 20 to 50% by weight, of the reinforcing agent, based on the total weight, while the impregnated glass fabrics, mats and / or nonwovens contain between 10 and 80% by weight % preferably contain between 30 and 60% by weight of copolymers, based on the total weight. Suitable pigments are, for example, titanium dioxide, cadmium, zinc sulfide, barium sulfate and carbon black. Other additives and auxiliaries are, for example, dyes, lubricants such as polytetrafluoroethylene, graphite or molybdenum disulfide, abrasives such as carborundum, light stabilizers and hydrolysis stabilizers. Wollastonite, calcium carbonate, glass balls, quartz powder, S and boron nitride or mixtures of these fillers can also be used. The pigments, additives and auxiliaries are usually used in amounts of 0.01 to 10% by weight, based on the weight of polyaryl ether ketones.

Example 1 (comparison)

0031109.1 g (0.5 mol) of 4,4'-difluorobenzophenone, 76.02 g (0.55 mol) of finely ground potassium carbonate and 1000 g of diphenyl sulfone were placed in a three-necked flask equipped with a stirrer, nitrogen inlet and air cooler. The starting materials were heated to about 180 ° C. under a nitrogen atmosphere, the diphenyl sulfone melting and the potassium carbonate being suspended finely. Then 55.06 g (0.5 mol) of hydroquinone were added, the temperature was raised to 200 ° C. and held for 2 hours. Then the temperature was kept at 240 ° C, 280 ° C and 320 ° C for 1 hour.

0032After the reaction mass had cooled and solidified, it was ground. The fine powder thus obtained was washed four times for 10 minutes with hot acetone, three times for 10 minutes with boiling water and again for 5 minutes with acetone to remove diphenyl sulfone and inorganic components. The polymer powder obtained was dried in vacuo at 150 ° C. for 10 hours.

0033The polymer consisting of recurring units of the formula<chemistry id="chem0016" num="0016"><img file="EP0275035A2_D0017.tif" /></chemistry> had a glass transition temperature of 141 ° C and a melting temperature of 339 ° C according to DSC measurements.

0034The reduced viscosity was 1.80 (measured in concentrated sulfuric acid at 25 ° C, 1 g polymer in 100 ml).

Example 2

003599.6 g (0.25 mol) of 4,4ʹ-di (4-hydroxyphenoxy) benzophenone, 54.55 g (0.25 mol) of 4,4ʹ-difluorobenzophenone, 38.0 g (0.275 mol) of potassium carbonate and 1000 g Diphenyl sulfone were filled in a four-neck glass flask equipped with a stirrer, nitrogen inlet, internal thermometer and air cooler and heated to 200 ° C. and held at this temperature for 1 hour. The reaction mass was then kept at 240 ° C., 280 ° C. and 320 ° C. for one hour each. After cooling, the reaction mass was comminuted and worked up as described in Example 1.

0036The properties of the polymer thus obtained are shown in Table 1.

Example 3

0037125.63 g (0.25 mol) of 1,4-di [4- (4-hydroxyphenoxy) benzoyl] benzene, 80.56 g (0.25 mol) of 1,4-di (4-fluorobenzoyl) benzene and 38 , 0 g (0.275 mol) of potassium carbonate were reacted and worked up in 1200 g of diphenyl sulfone under the conditions described in Example 2. The properties of the polymer thus obtained are shown in the table.

Example 4

0038125.63 g (0.25 mol) of 1,4-di [4 (4-hydroxyphenoxy) benzoyl] benzene, 54.55 g (0.25 mol) of 4,4-difluorobenzophenone and 38.0 g (0.275 mol) Potassium carbonate was reacted and worked up in 1200 g of diphenyl sulfone under the conditions described in Example 2. The properties of the polymer obtained are shown in the table.

Example 5

0039144.66 g (0.25 mol) of 4,4ʹ-di [4-hydroxyphenoxy) benzoyl] diphenyl, 80.56 g (0.25 mol) of 1,4-di (4-fluorobenzoyl) benzene and 38.0 g (0.275 mol) of potassium carbonate were reacted and worked up in 1200 g of diphenyl sulfone under the conditions described in Example 2. The properties of the polymer obtained are shown in the table.<tables id="tabl0002" num="0002"><img file="EP0275035A2_D0018.tif" /></tables>