(Per) fluoropolyether additives

Abstract

Compounds usable as stabilizing additives of perfluoropolyether fluids working at high temperatures, higher than 200° C. and/or in the presence of metals and/or in the presence of Lewis acids, are formed of (per)fluoropolyether chains and of end groups having a heteroaromatic structure, according to the following general formula: T 1 -CFW 1 —O—R f —CFW 2 -T 2   (I) wherein T 1 , T 2 , equal to or different from each other, have the following meanings: F, CF 3 , C 2 F 5 , (C 2 F 4 )Cl —CH 2 —B—Y, —CH(CF 3 )O—Y, wherein: B═O, S: Y is a substituent formed of a ring having a heterocyclic structure having the following formula: wherein: R 1 , R 2 , R 3 , R 4 , equal to or different from each other are H, linear or branched C 1 -C 8 perfluoroalkyl, NO 2 , CN, preferably H; with the proviso that at least one of the two end groups T 1 , T 2 is —CH 2 —B—Y or —CH(CF 3 )O—Y, wherein B and Y are as above: W 1 , W 2 , equal to or different from each other, are —F, —CF 3 : Rf is a (per)fluoropolyoxyalkylene chain having a number average molecular weight between 500 and 10,000, preferably between 800 and 5,000.

1 . Compounds usable as stabilizing additives of fluorinated, preferably perfluoropolyether, fluids, working at high temperatures, higher than 200° C., up to 280° C. in the presence of Lewis acids, said compounds being formed of (per)fluoropolyether chains and of end groups having a heteroaromatic structure, according to the following general formula:  
       T 1 -CFW 1 —O—R f —CFW 2 -T 2    (I)  wherein    T 1 , T 2 , equal to or different from each other, have the following meanings: 
 F, CF 3 , C 2 F 5 , (C 2 F 4 )Cl;  
 —CH 2 —B—Y, —CH(CF 3 )O—Y, wherein: 
 B═O, S;  
 
 Y is a substituent formed of a ring having a heterocyclic structure having the following formula:  
                     
   wherein: 
 Q is equal to O, S or to the —CH═N— group;  
 R 1 , R 2 , R 3 , R 4 , equal to or different from each other are H, linear or branched C 1 -C 8  perfluoroalkyl, NO 2 , CN, preferably H;  
 with the proviso that at least one of the two end groups T 1 , T 2  is CH 2 —B—Y or —CH(CF 3 )O—Y, wherein B and Y are as above;  
   W 1  and W 2 , equal to or different from each other, are —F, —CF 3 , preferably F;    Rf is a (per)fluoropolyoxyalkylene chain comprising one or more repeating units, statistically distributed along the polymeric backbone, having the following structure: 
 (CFXO), (C 2 F 4 O), (CF 2 CF 2 CF 2 O), (CF 2 CF 2 CF 2 CF 2 O), (C 3 F 6 O) (CR 5 R 6 CF 2 CF 2 O);  
   wherein X is F, CF 3 ; R 5  and R 6 , equal to or different from each other, are selected from H, Cl, or perfluoroalkyl from 1 to 4 carbon atoms, R f  having a number average molecular weight from 500 to 10,000, preferably from 800 to 8,000, still more preferably from 2,000 to 5,000;    
   
   
       2 . Compounds according to  claim 1 , wherein in the formula of the substituent Y when Q is CH═N, N is linked to the aromatic ring and the compound belongs to the quinoxaline class.  
   
   
       3 . Compounds according to  claim 1 , wherein the fluorinated, preferably perfluoropolyether, fluids, work at high temperatures, higher than 200° C., up to 280° C., in the presence of Lewis acids and in the presence of metals.  
   
   
       4 . Compounds according to  claim 1 , wherein the perfluoropolyether chain R f  is selected from the following structures:  
       —(CF 2 CF(CF 3 )O) a (CFXO) b —CF 2 (R′ f )CF 2 —O—(CF 2 CF(CF 3 )O) a (CFXO)b-   (A)  wherein R′ f  is a fluoroalkylene group from 1 to 4 C atoms; X is as above; a and b are integers such that the number average molecular weight is within the above range; a/b is between 10 and 100 where b is different from 0;      —(CF 2 CF 2 O) c (CF 2 O) d (CF 2 (CF 2 ) z O) h —  (B)    wherein c, d and h are integers such that the number average molecular weight is within the above range; c/d is between 0.1 and 10 where d is different from 0; h/(c+d) is between 0 and 0.05 where (c+d) is different from 0; z is 2 or 3; h can also be equal to 0;      —(C 3 F 6 O) a (CF 2 CF 2 O) f (CFXO) g —  (C)    wherein X is as above; e, f, g are integers such that the number average molecular weight is within the above range; e/(f+g) is between 0.1 and 10 where (f+g) is different from 0; f/g is between 2 and 10, where g is different from 0;      —(CF 2 (CF 2 ) z O) s —  (D)    wherein s is an integer such as to give the molecular weight in the above range, z has the meaning as above;      —(CR 5 R 6 CF 2 CF 2 O) p′ —R′ f —O—(CR 5 R 6 CF 2 CF 2 O) q′ —  (E)    wherein R 5  and R 6  are equal to or different from each other and selected from H, Cl or perfluoroalkyl from 1 to 4 C atoms; R′ f  is as above; p′ and q′ are integers such that the molecular weight is in the above range;      —(CF(CF 3 )CF 2 O) j″ —R′ f —O—(CF(CF 3 )CF 2 O) j ″—  (F)    j″ being an integer such as to give the molecular weight indicated above, R′ f  being as above.    
   
   
       5 . Compounds according to  claim 4 , wherein Rf is selected between (A) and (B), preferably (B).  
   
   
       6 . Lubricating compositions comprising: 
 a fluorinated oil or grease, preferably having a perfluoropolyether structure;    from 0.05% to loo by weight, preferably from 0.1% to 5% by weight, still more preferably from 0.5% to 2% by weight on the whole composition, of the compounds of formula (I).    
   
   
       7 . Compositions according to  claim 6 , wherein the perfluoropolyethers usable as oils or as components for preparing greases are selected from the following classes:  
       E-O—[CF(CF 3 )CF 2 O] n ′(CFXO) n′ -E′  (1)  wherein: 
 X is as above;  
 E and E′, equal to or different from each other, are selected from —CF 3 , —C 2 F 5  or —C 3 F 7 ;  
   m′ and n′ are integers such that the m′/n′ ratio is between 20 and 1,000 where n′ is different from 0 and the viscosity of the product measured at 20° C. is within the limits indicated below; the above indicated repeating units are statistically distributed along the chain.      C 3 F 7 O—[CF(CF 3 )CF 2 O] o′ ,-D   (2)    wherein: 
 D is equal to —C 2 F 5  or —C 3 F 7 ;  
 o′ is an integer such that the viscosity of the product is within the range indicated below.  
   (C 3 F 7 O—[CF(CF 3 )CF 2 O] p′ —CF(CF 3 )—) 2   (3)  
   wherein: 
 p′ is an integer such that the viscosity of the product is within the range indicated below.  
   E-O—[CF(CF 3 )CF 2 O] q′ (C 2 F 4 O) r′ (CFX) s′ -E′  (4)  
   wherein: 
 X is as above;  
 E and E′, equal to or different from each other, are as above; q′, r′ and s′ are integers, including 0, such that the viscosity of the product is within the range indicated below;  
   E-O—(C 2 F 4 O) t′ (CF 2 O) u′ -E′  (5)  
   wherein: 
 E and E′, equal to or different from each other, are as above;  
 t′ and u′ are integers such that the t′/u′ ratio is between 0.1 and 5 where u′ is different from 0 and the viscosity of the product is within the limits indicated below.  
   E-O—(CF 2 CF 2 CF 2 O) v′ -E′  (6)  
   wherein: 
 E and E′, equal to or different from each other are as above;  
 v′ is a number such that the viscosity is within the range indicated below.  
   D-O—(CF 2 CF 2 O) z′ -D′  (7)  
   wherein: 
 D and D′, equal to or different from each other, are as above;  
 z′ is an integer such that the viscosity of the product is within the range indicated below;  
 the viscosity measured at 20° C. of said perfluoropolyether oils being between 10and 10,000cSt, preferably between 300and 2,000cSt.  
   
   
   
       8 . Compositions according to  claim 7 , wherein perfluoropolyether oils selected from the classes (1), (4) and (5) are used.  
   
   
       9 . Compositions according to  claim 6 , comprising anti-wear additives.  
   
   
       10 . Compositions according to  claim 6 , wherein the grease contains one or more perfluoropolyether oils and thickening additives selected from PTFE, optionally sodium terephthalate, calcium or lithium soaps, polyurea.  
   
   
       11 . Compositions according to  claim 10 , comprising as dispersing additives, surfactants, preferably non ionic, and having a perfluoropolyether or perfluoroalkyl structure; talc or inorganic fillers.  
   
   
       12 . A process for obtaining the compounds of formula (I) of  claim 1 , said process comprising the following steps: 
 a) formation of an alcoholate or thiolate, by reaction of a compound having a (per)fluoropolyoxyalkylene structure of formula:      T′ 1 -CFW 1 —O—R f —CFW 2 -T′ 2    (II)    wherein: 
 Rf, W 1  and W 2  have the above meanings;  
 T′ 1  and T′ 2 , equal to or different from each other, represent an end group selected from the following: CH 2 OH, CH 2 SH, CH(OH)CF 3 , F, CF 3 , C 2 F 5 , (C 2 F 4 ) Cl;  
 with the proviso that at least one of the two end groups T′ 1  and/or T′ 2  is equal to CH 2 OH, CH 2 SH, CH(OH)CF 3 , CH(SH)CF 3 ;  
 with an organic or inorganic base, in an organic solvent inert under the reaction conditions, at a temperature between 20° C. and 100° C., preferably between 20° C. and 30° C.;  
   b) reaction of the alcoholate or thiolate obtained in step a) with a compound of formula                          wherein Q, R 1 , R 2 , R 3 , R 4  have the above meaning, V′ is a halogen atom selected from C 1 , Br, I;    step b) being carried out in an organic solvent inert under the reaction conditions, preferably the same used in step a), at temperatures between 20° C. and 100° C., preferably between 40° C. and 80° C.;    c) isolation of the product from the reaction mass.    
   
   
       13 . A process according to  claim 12 , wherein the organic solvent used is selected from hydrogenated solvents, preferably terbutyl alcohol, acetonitrile, diglyme, DMF, toluene, xylene; fluorinated or hydrofluorinated solvents, having a boiling point between 20° C. and 150° C., preferably between 40° C. and 100° C.  
   
   
       14 . A process according to  claim 12 , wherein in step a) the ratio by weight solvent/(per)fluorinated alcohol or thiol ranges from 0.5 to 10, preferably from 2 to 5.  
   
   
       15 . A process according to  claim 12 , wherein the base used in step a) is an organic or inorganic base, preferably potassium terbutylate, KOH and NaH.  
   
   
       16 . A process according to  claim 12 , wherein in step a) the ratio in equivalents between. the base and compound (II) ranges from 1.1 to 2, preferably from 1.2 to 1.5.  
   
   
       17 . A process according to  claim 12 , wherein in step b) the ratio [equivalents of the alcoholate or thiolate function of the (per)fluoropolyether]/moles of the compound (III) ranges from 1 to 0.5, preferably from 0.8 to 0.6.  
   
   
       18 . Use of the compounds of  claim 1  as stabilizing additives of compositions of fluorinated lubricating oils and greases, preferably having a perfluoropolyether structure.  
   
   
       19 . Use according to  claim 18 , wherein the compositions of lubricating oils and greases are used at high temperatures in the presence of Lewis acids.  
   
   
       20 . Use according to  claim 19 , wherein the compositions of lubricating oils and greases take place in the presence of metal.  
   
   
       21 . Use according to  claim 19 , wherein the utilization temperatures are equal to or higher than 200° C., up to 280° C.