Process for preparing polyether ketones
FIELD 
     The present invention concerns a process for preparing polyether ketone polymers by the catalyzed coupling of bishaloarylketones, with alkali metal carbonates serving as the source of ether oxygen. Polyether ketone polymers are useful in composite and fiber applications. 
     TECHNICAL BACKGROUND OF THE INVENTION 
     Recent entries into the field of high performance resins and fibers include polyphenylene sulfides, polyetherimides, aromatic polyether-ether ketones (PEEK) and aromatic polyether-ketone-ketones (PEKK). This invention concerns a process for preparing aromatic polyether-ketone-ketones (PEKK). PEKK polymers are currently being made via a two step AlCl 3  based Friedel-Craft reaction. Such a process requires virtually stoichiometric quantities of AlCl 3  in both steps and also a recrystallization of the material to arrive at the desired isomer. The removal of excess AlCl 3  by an extraction and a purification step requires the use of large, ususally expensive, corrosion resistant vessels and drying equipment. 
     The present invention provides an improvement over the above Friedel-Craft system as it is a one step method and does not require an extensive extraction procedure. 
     I. Fukawa et al., Macromolecules 24, 3838-3844 (1991) disclose a process for the preparation of aromatic poly(ether ketones) (PEK) by the reaction of an aromatic dihalide with sodium carbonate in the presence of high surface area solid silica catalyst with copper salt co-catalyst. Formation of a PEKK from 1,4-bis(4-fluorobenzoyl)benzene (identified as 4,4&#34;-difluoroterephthalophenone) is reported. Fukawa reported that the reaction occurs on the internal surfaces of pores in the silica particles and on the external surfaces of the silica particles. The present invention presents an improvement over the Fukawa et al. process because the silicon based catalysts used in the present process are more easily separated from the polymer than are the silica particles used by Fukawa et al. For example, present catalysts may be separated by liquid extraction under non-alkaline conditions. 
     H. R. Kricheldorf and G. Bier, Polymer, 25, 1151-1156 (1984) disclose the preparation of poly(ether ketone)s and poly(ester ether ketone)s by the reaction of 4,4&#39;-difluorobenzophenone with silylated bisphenols. 
     H. R. Kricheldorf and P. Jahnke, Makromol. Chem, 191, 2027-2035 (1990), disclose the preparation of poly(ether sulfone)s by the reaction of 4,4&#39;-dichlorodiphenyl sulfone with silylated bisphenols. 
     H. R. Kricheldorf and P. Jahnke, Makromol. Chem., Rapid Commun. 12, 331-335 (1991), disclose the silicon catalyzed synthesis of poly(ether-sulfones) from 4,4&#39;-dihalogenodiphenyl sulfones in the presence of potassium carbonate and N-methylpyrrolidone and N-phenylpyrrolidone solvent. 
     H. R. Kricheldorf, Makromol. Chem., Macroml. Symp., 54/55, 365-388 (1992), discloses various polymer synthetic methods that involve the polycondensation of silylated aromatic monomers. 
     SUMMARY OF THE INVENTION 
     This invention provides a process for preparing poly-ether ketones by contacting one or more bishaloarylketones, by the silanolate/copper salt or silanolate/copper oxide catalysis of ether bridge formation between bischloroarylketones or bisfluoroaryl-ketones using oxygen-containing alkali metal salts as the source of the ether oxygen atom. 
     The process comprises reacting bischloroarylketones or bisfluoroarylketones under polymerizing conditions in the presence of 
     a) a catalyst selected from the group consisting of alkali metal silanolates, halosilanes and silanols; 
     b) a copper containing catalyst; 
     c) a source of oxygen; and 
     d) a solvent in which said catalyst is soluble. 
     This invention also includes the above process with the addition of a catalytic amount of a co-catalyst, for example cesium fluoride. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Poly(ether ketone ketone), PEKK, is a polymer system with exceptional thermal, hydrolytic, solvent and flame resistance. This invention provides a process for the preparation of this high value polymer system. 
     Provided is a process for the preparation of polyether ketone ketones, PEKK, by the silanolate/copper salt or silanolate/copper oxide catalysis of ether bridge formation between bis chloroaryl ketones or bis fluoroaryl ketones using oxygen-containing alkali metal salts as the source of the ether oxygen atom. 
     Preferred starting materials include 1,4-bis (4-halobenzoyl)benzene and 1,3-bis (4-halobenzoyl) benzene or a mixture thereof. The most preferred halo group is fluoro. 
     Preferred silicon containing catalysts for this process include sodium, potassium, cesium or rubidium silanolate, halosilanes, including chloro, bromo, iodo and fluoro silanes, silanols--including silanol ending polydimethylsilozanes, hexaalkylcyclotrisiloxanes, disilazanes and dialkylaminotrialkylsilanes. Most preferred silanolates are potassium trimethyl silanolate and potassium triphenyl silanolate. Most preferred halosilanes are triphenylsilylchloride, triphenylsilylfluoride, trimethylsilylchloride and trimethylsilylfluoride. 
     Preferred copper containing co-catalysts catalysts for this process comprise copper, cuprous chloride, cuprous bromide, cupric chloride, cupric bromide, cupric acetate, copper(I) oxide and copper(II) oxide. Most preferred is copper(II) chloride. 
     Oxygen sources include alkali metal carbonates. Preferred oxygen sources comprise sodium carbonate and potassium carbonate. Most preferred is potassium carbonate. 
     Preferred reaction solvents, in which said catalysts should be essentially soluble, include phenyl sulfone, phenyl ether, tetramethylene sulfone and N-cyclohexyl pyrrolidinone. Most preferred is phenyl sulfone. The catalysts can later, after polymerization, be separated by washing the product with a second solvent. 
     Preferred optional co-catalysts comprise alkali metal fluorides, most preferably cesium fluoride. 
     The polymerization process is run at elevated temperatures, usually from about 200° C. to about 340° C. Preferably, the reaction is run at about 300° C. to about 330° C. 
     Although it is possible to carry out the polymerization reaction at reduced or elevated pressures, it is preferred to carry out the reaction at atmospheric pressure. 
     The products formed by the process described herein are as used as films, coatings, fibers, composite matrices, adhesives and foams in industrial and aerospace applications that require flame resistance, high heat distortion temperatures and solvent and chemical resistance. 
     EXAMPLES 
     Example 1, below describes the preparation of PEKK(T/I-60/40). Additional examples appear in Table I. 
     In the following example, bis-1,3-(4-fluorobenzoyl)benzene and bis-1.4-(4-fluorobenzoyl) benzene were prepared according to the method of P. M. Hergenrother, N. T. Wakelyn and S. J. Havens, J. Polym. Sci., Part A, Polym. Chem., 25, 1093, (1987). Bis-1,-3-(4-chlorobenzoyl)benzene and bis-1,4-(4-chlorobenzoyl)benzene were prepared according to the method of P. M. Hergenrother and B. J. Jensen, Polymer Prepr, ACS Division Polym Chem., 2(2), 1974(1985). 
     EXAMPLE 1 
     To a 2.2 cm I.D. polymer tube with a glass stirrer having a stirring element consisting of three 1.7 cm O.D. and 1.1 cm I.D. ringlets atop one another and nitrogen inlet, was added 1.934 g of 1,4-bis(4-fluorobenzoyl)benzene, 1.289 g of 1,3-bis(4-fluorobenzoyl)benzene, 0.256 g of potassium trimethylsilanolate, 1.38 g of potassium carbonate, 3 g of phenyl sulphone, 0.015 g of cuprous chloride and 0.076 g of cesium fluoride. The tube was connected to a dry nitrogen line and was alternately evacuated and back filled with nitrogen to free the system of air. The tube was then lowered into a 250° C. Woods metal bath and heated with stirring for 0.75 hour. The temperature of the bath was raised to 320° C. and stirring continued for 4 hours. The viscous mixture was allowed to cool to room temperature after which methanol was poured on top of the solid. The reactor was transferred to an ultrasonic bath where the solid mass was transformed into a slurry. The mixture was filtered by suction through a sintered glass Buchner funnel. The solid was washed 3 times with hot methanol in a Waring blender with filtration after each wash. The solid was washed once with hot water and finally once with hot methanol. The polymer was dried in a 100° C. vacuum oven. Yield 3.08 g (103%). The inherent viscoisty was 0.57 in 98% sulfuric acid at 30° C. measured at 0.5 g/dL. The polymer exhibited a PMT (see Table I for reference to method) of 276° C. and yielded fibers several inches long when pulled from a hot bar at 320° C. 
     
                                           TABLE I                                 
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PREPARATION OF PEKK                                                       
     1,4 Bis FBz*/                                                        
              Me.sub.3 SiOK                                               
                    CuCl.sub.2                                            
                        K.sub.2 CO.sub.3                                  
                            Ph.sub.2 SO.sub.2                             
                                 CsFl                                     
                                    Reaction Temp.                        
Example                                                                   
     1,3 Bis FBz (g/g)                                                    
              (g)   (g) (g) (g)  (g)                                      
                                    C./time, h                            
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2    1.934/1.289                                                          
              0.256 0.03                                                  
                        1.38                                              
                            3    0  320/5                                 
                    (CuCl)                                                
3    1.934/1.289                                                          
              0.321 0.042                                                 
                        1.725                                             
                            3.5  0.046                                    
                                    250/0.75                              
                                    320/4                                 
4    1.934/1.289                                                          
              0.321 0.08                                                  
                        1.725                                             
                            3.5  0.046                                    
                                    250/0.75                              
                                    320/4                                 
5    1.934/1.289                                                          
              0.513 0.08                                                  
                        1.38                                              
                            6    0.015                                    
                                    250/0.75                              
                                    320/4                                 
6    1.934/1.289                                                          
              0.513 0.08                                                  
                        2.07                                              
                            6    0.076                                    
                                    250/0.75                              
                                    320/4                                 
7    1.934/1.289                                                          
              0.128 0.08                                                  
                        1.38                                              
                            1    0.015                                    
                                    250/0.75                              
                                    320/4                                 
8    1.934/1.289                                                          
              0.128 0.08                                                  
                        1.38                                              
                            6    0.015                                    
                                    250/0.75                              
                                    320/4                                 
9    1.934/1.289                                                          
              0.321 0.042                                                 
                        2.07                                              
                            3.5  0.046                                    
                                    250/0.75                              
                                    320/4                                 
10   1.934/1.289                                                          
              0.256 0.015                                                 
                        1.38                                              
                            3    0.076                                    
                                    320/4                                 
11   1.934/1.289                                                          
              0.256 0.015                                                 
                        1.38                                              
                            3    0.076                                    
                                    320/3                                 
12   1.934/1.289                                                          
              0**   0.015                                                 
                        1.38                                              
                            3    0.076                                    
                                    260/0.5                               
                                    320/3                                 
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 *1,4- and 1,3bis(4-fluorobenzoyl)-benzene                                
 **0.294 g Ph.sub.3 SiCl used as a catalyst                               
 
    
     
                                           TABLE II                                
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RESULTS OF PREPARATION                                                    
                     Yield                                                
                          Inherent Viscosity                              
                                         Comments on Polymer              
Example                                                                   
     Comments on Polymerization                                           
                     (g)  in H.sub.2 SO.sub.4, dL/g                       
                                   PMT* °C.                        
                                         Behavior                         
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2    Polymer was isolated by                                              
                     1.94 0.19     246                                    
     washing 3X with hot MeOH, 3X                                         
     with hot water/acetone                                               
     (50/50) then with MeOH in                                            
     Soxhlet extractor for 48 h.                                          
3    Amber initially, then hazy                                           
                     3.27 Insol.   No melt                                
                                         Film pressed at 300°      
                                         C./14 psi                        
     opaque (1 h). At 4 h dark     to 400                                 
                                         (97 kPa) was leathery brown      
     maroon unstirrable solid            and tough                        
4    Opaque brown mixture                                                 
                     3.78 0.41     261   Integral film pressed at         
     initially. At 2 h brown             275° C./14 psi (97 kPa).  
                                         Long                             
     stirrable mixture. At 4 h           fibers obtained from 320 hot     
     brown thin stirrable mixture        bar                              
5    Initially dark brown fluid                                           
                     4.5  Insol.   No melt                                
                                         Film pressed at 300°      
                                         C./14 psi                        
     translucent changed to dark   to 400                                 
                                         was leathery brown and tough     
     brown unstirrable mixture                                            
     after 4 h. On setting at RT                                          
     cracked inside peeling                                               
     fragments away which adhered                                         
     to solid.                                                            
6    Tan opaque initially. At 4 h,                                        
                     3.33 0.81     302                                    
     wet reddish brown paste                                              
7    At 4 h a maroon color                                                
                     3.08 0.57     276   Long fibers obtained from        
     stirrable thick fluid               surface at 320° C. hot    
                                         bar                              
8    At 4 h a stirrable thin                                              
                     3.26 0.36     234   Long fibers obtained from        
     reddish brown melt                  surface of 320° C. hot    
                                         bar                              
9    At 4 h a unstirrable hard                                            
                     1.72 0.41     No melt                                
     reddish brown mass was                                               
                          partly soluble                                  
                                   to 400                                 
     obtained                                                             
10                   3.1  0.8      277   Polymer exhibited excellent      
                                         adhesion for &#34;Kapton&#34; film       
11   0.32 g of Polyethylene glycol                                        
                     3.08 1.07     248                                    
     1450 (Baker Chemicals) added                                         
     to rex&#39;n                                                             
12   0.294 g of Ph.sub.3 SiCl w&amp;s                                         
                     2.7  1.07     277                                    
     instead of KOSiMe.sub.3                                              
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 *Method described for polymer melt temperature in Sorenson, W.; Campbell,
 T.W., Preparative Methods of Chemistry, 2nd ed., Interscience: New York, 
 1968, pp. 57-59, Method A