Title of Invention

A PROCESS FOR THE SYNTHESIS OF POLYARYLENE ETHER KETONE RESINS

Abstract

This invention relates to a process for the synthesis of polyarylene ether ketone. Dihalobenzophenones are condensed with dihydroxy aromatic compounds such as esorcinol and hydroquinone. The reaction is carried out in the presence of anhydrous alkaline carbonate and benzophenone in the presence of an aromatic hydrocarbon solvent. The mixture is preferably heated upto 240oC. The polymer is recovered from the reaction mixture by known means.

Full Text

This invention relates to a process for the synthesis of polyarylene ether ketone resins. ether Polyarylene Jketone resins have gained rapid accetpance for use in advanced thermoplastic resin composites for aerospace structural applications and for storing cryofluids at low temperatures. These polymers exhibit excel lent acid and alkali resistance and show very good dimentional stability. They are thermally stable and have melt. processabi1 ity . ether Polyarylene / ketones are polymers having a molecular chain consisting of phenylene groups, oxygen atoms and ketone groups. Conventionally these resins are prepared in the presence of high boi1ing solvents like dipheny1 sulphone, N-cyclohexy1-2-pyrrolidone and sulpholane. A major draw back of the existing process is the high cost of the solvents and the inability of solvent recovery for future use. The main objectives of this invention ar& in providing a process for the synthesis of polyarylene ether ketones using less expensive and easily recoverable solvents and to obtain polymers in good yield having an inherent viscosity 0.3 to 75 dL/g. 4,4'-dinalobenzophenones is subjected nucleophi1ic substitution reaction with hydroquinone, resorcinol, 4,4'- dihydroxybenzophenone and bisphenol-A using benzophenone as an * inert solvent in the presence of anhydrous alkali carbonate. The The dihalocompund may be difluoro, dichloro and diiodo compounds or these mixtures- Alkali carbonates can be sodium carbonate, potassium carbonate or a mixture of these two- The proportion of the carbonate is not relevant - Initially, the hydroquinone, resorcinol or 4,4'-dihydroxy benzophenone or bisphenol-A added as one of the monomer reacts with the alkali carbonate to form a salt. This reaction is preferably carried out in a hydrocarbon solvent selected from benzene, toluene, xylene or a mixture thereof in any porportion. The nucleophilic formation of polyarylene ketone may take place simultaneously with the formation of alkaline salt of the respective dihydroxy monomer. The monomer to benzophenone solvent ratio by weight may vary from 1:4 to 1:7 and the molar ratio of the dihydroxy monomer to alkali metal carbonate can vary from 1:1 to 1:3. the ratio between the monomer and the azotropic hydrocarbon solvent may be between 1:4 to 1:6- Instead salt formation takes place at a temperature between 110°C to 160°C and the polymerisation takes place between 160° to 240°C though these temperature ranges are not critical to the reaction. The reaction may be complete from 2 to 7 hours. Polymerization takes place through the nucleophilie substitution of the halobenzophenone and the alkalimetal salt of the hydroquinone or resorcinol or 4,4'-dihydroxy benzophenone or bisphenol-A monomer resulting in the formation of arylene ether bond. Alkali metal halide is the by product. A process for the synthesis of polyarylene ether ketone resin according to this invention comprises the steps of reacting dihalobenzenephenone wi th dihydroxy substituted aromatic compounds such as dihydroquinone, resorcinoi, bisphenol-A, 4,4'-dihydroxybenzophenone or mixtures thereof in the presence of at least one anhydrous aIkalicarbonate benzophenone and at least one hydrocarbon solvent, and recovering the product from the reaction mixture by known methods. This process for synthesis results in high molecular weight polymers in good yield. The solvent is recoverable for reuse. The temperature of the reaction is not very high. Further depending on the aromatic moities of the dihydroxymonomer , further chemical modi fieation of the ketone resin is possible. The following examples ^re only illustrative of the invented process. Example 1 Synthesis of polyarylene ether etherketone (PEEK-I) from 4,4'-difluorobenzophenone and hydroquinone (1:1 mole ratio). A four necked reaction kettle fitted with a stirrer condenser, thermocouple, inlet and outlet for inert gas (outlet is through Dean-stark condenser and a calcium chloride guard tube) is charged with 5.04g (0.045 mole) of hydroquinone, 90g of ben/opnenone, 7.59g (0.0549 mole) of anhydrous K2CO3 and 80 ml of Cjrll_M| toluene. The reaction mixture was slowly heated to 150°C and ^ater was removed by azeotropic disti1lation with toluene for a period of 4 hours. The reaction mixture was cooled to about l00nC, and 10g (0.045 mole) of 4,4'-difluorobenzophenone was addc*d, The poly condensation reaction was continued for 2 - 5h at 165°C and 2.5h at 230°C. The viscous reaction mixture was cooled to room temperature. The product was refluxed with water repeatedly and subjected to soxhlet extraction with acetone for 16 hours and dried under vacuum at 100°C for 12h. PEEK-I is obtained in 13.00g (98*/.). The structure of the product was confirmed by infra-red and nuclear magnetic resonance spectroscopy. The obtained polymer had eta inh = 0.75dL/g, Tg -146°C and Tm = 338°C. TGA curve of PEEK-I recorded in nitrogen atmosphere shows that it is stable upto 520°C and undergoes degradation above this temperature leaving behind a char residue of 50'/. at 900°C. Example 2 Synthesis of polyarylene ether ether ketone (PEEK-II) from 4,4'-diehiorobenzophenone and hydroquinone (1:1 molar ratio). A four necked reaction kettle fitted with a stirrer condenser, thermocouple, inlet and outlet for inert gas (outlet is through Dean-stark condenser and a calcium chloride guard tube) is charged with 5.04g (0.045 mole) of hydroquinone, 90g of benzophenone, 7 . 59g (0.0549 mole) of anhydrous K2C03 and 80 ml of dried toluene. The reaction mixture was slowly heated to 150 C and water was removed by azeatropic disti11 ation with toluene for a period of 4 hours. The reaction mixture was cooled to about 100°C, and 11.5g (0.045 mole) of 4,4'-difluorobenzophenone was added. The polyeondensation reaction was continued for 2 . 5h at 165°C and 2.5h at 230°C. The viscous reaction mixture was cooled to room temperature. The product was refluxed with water repeatedly and subjected to soxhlet extraction with acetone for 16 hours and dried under vacuum at 100°C for 12h. PEEK-II is obtained in 12. 4g (94*/.) . The structure of the product was conf irmed by infra-red and nuclear magnetic resonance spectroscopy. The obtained polymer had eta inh = 0.30dL/g, Tg = 145°C and Tm = 335°C. TGA curve of PEEK-II recorded in nitrogen atmosphere shows that it is stable upto 480°C and undergoes degradation above this temperature leaving behind a char residue of 457. at 900°C. Scheme 1 depicts the synthesis of polyarylene ether ketone from 4,4'-dihalobenzophenone and dihydroxymonomer (1:1 mole ratio). The appended claims do not exclude obvious equivalents known to persons skilled in the art. WE CLAIM: 1. process for the synthesis of polyarylene ether ketone resin comprising the steps of reacting dihalobenybphenone with dihydroxy substituted aromatic compounds such as nydroquinone, resorcinol, bisphenol-A, 4,4'~dihydroxybenzophenone or mixtures thereof in the presence of at least one anhydrous alkali carbonate} benzophenone and atleast one hydrocarbon solvent and recovering the product from the reaction mixture by (known methods. ^^N 2 - The process as c1 aimed in claim I, wherein the reaction mixture is initially heated to a temperature of 110°C to 168DC ^nd then upto 240DC. 3- The process as claimed in claims 1 and 2, wherein 4,4'- dihalobenzophenone is 4,4'-difluorobenzophenone or 4,4'-dichlorobenzophenone or mixtures thereof. 4. The process as c1 aimed in claims 1-3, wherein said alkali carbonate is selected from sodium carbonate, potassium carbonate or a mixture thereof. 5. The process as c1 aimed in claims 1-4, wherein said hydrocarbon solvent is selected from benzene, toluene, xylene or mi xtures thereof. 6. The process as c 1 aimed in claims i to 5, wherein the ratio of ben2ophenone to the dihydroxyaromatic compound is between 4:1 to 7:1 by weight - 7. The process as claimed in claims 1—6, wherein the reaction is allowed to proceed for a period of 2 hours to 7 hours. 8- A process for the synthesis of polyarylene ether ketone resin substantially as herein described and exemplified-

Documents:

0292-mas-2000 abstract-duplicate.pdf

292-mas-2000-abstract.pdf

292-mas-2000-claims duplicate.pdf

292-mas-2000-claims original.pdf

292-mas-2000-correspondance others.pdf

292-mas-2000-correspondance po.pdf

292-mas-2000-description complete duplicate.pdf

292-mas-2000-description complete original.pdf

292-mas-2000-form 1.pdf

292-mas-2000-form 19.pdf

292-mas-2000-form 26.pdf

292-mas-2000-form 3.pdf