Lubricant compositions for vacuum pumps

Abstract

The invention pertains to a lubricant composition comprising: (A) at least one non-functional (per)fluoropolyether oil (PFPE oil) comprising at least one (per)fluoropolyoxyalkylene chain (chain R F ); (B) at least one cyclic phosphazene compound [compound (P)] comprising one or more cyclic moieties having formula (I) or (II) here below: said cyclic moieties comprising, bound to one or more phosphorus atoms, at least one substituent comprising at least one (per)fluoropolyoxyalkylene chain (chain R′ F ); (C) at least one functional (per)fluoropolyether derivative (functional PFPE derivative) different from compound (P) comprising at least one (per)fluoropolyoxyalkylene chain (chain R′ F ) and at least one functional group comprising at least one monocyclic or polycyclic aromatic ring, said aromatic ring optionally containing one or more heteroatoms selected from N, O and S and one or more substituents different from hydrogen atoms.

1 . A lubricant composition comprising:
 (A) at least one non-functional (per)fluoropolyether oil (non-functional PFPE oil) comprising at least one (per)fluoropolyoxyalkylene chain (chain R F );   (B) at least one cyclic phosphazene compound [compound (P)] comprising one or more cyclic moieties having formula (I) or (II) here below:   
       
         
           
           
               
               
           
         
       
       said cyclic moieties comprising, bound to one or more phosphorus atoms, at least one substituent comprising at least one (per)fluoropolyoxyalkylene chain (chain R′ F ); and 
       (C) at least one functional (per)fluoropolyether derivative (functional PFPE derivative) different from compound (P) comprising at least one (per)fluoropolyoxyalkylene chain (chain R′ F ) and at least one functional group comprising at least one monocyclic or polycyclic aromatic ring, said aromatic ring optionally containing one or more heteroatoms selected from N, O and S and one or more substituents different from hydrogen atoms. 
     
     
         2 . The lubricant composition of  claim 1 , wherein the non-functional PFPE oil is selected from the group consisting of followings:
   T 1 -O—(C 2 F 4 O) b1′ (CF 2 O) b2′ -T 1′   (1)
   
       wherein:
 T 1  and T 1′ , equal to or different from each other, are independently selected from —CF 3 , —C 2 F 5  and —C 3 F 7  groups; 
 b1′ and b2′, equal to or different from each other, are independently integers ≧0 such that the b1′/b2′ ratio is comprised between 0.1 and 5 and the (b1′+b2′) sum is comprised between 5 and 250; should b1′ and b2′ be both different from zero, the different recurring units are generally statistically distributed along the perfluoropolyoxyalkylene chain.
   T 2 -O—(CF 2 O) c1′ (CF 2 CF 2 O) c2′(CF   2 CF 2 CF 2 O) c3′ (CF 2 CF 2 CF 2 CF 2 O) c4′ -T 2′   (2)
 
 
 
       wherein:
 T 2  and T 2′ , equal to or different from each other, are independently selected from —CF 3 , —C 2 F 5 , —C 3 F 7 , —C 4 F 9 , —CF 2 C1, —CF 2 CF 2 C1 groups; 
 c1′, c2′, c3′ and c4′, equal to or different from each other, are independently integers ≧0 such that the number average molecular weight is comprised between 700 and 100000; 
 the c2′/c1′ ratio is comprised between 2 and 20; 
 the (c3′+c4′)/(c1′+c2′+c3′+c4′) ratio is comprised between 0.05 and 0.2; 
 the c1′/(c1′+c2′+c3′+c4′) ratio is comprised between 0.05 and 0.4; 
 
       should at least two of c1′, c2′, c3′ and c4′ be different from zero, the different recurring units are generally statistically distributed along the perfluoropolyoxyalkylene chain.
   T 3 -O—(CF 2 CF 2 O) d′ -T 3′   (3)
 
 
       wherein:
 T 3  and T 3 ′, equal to or different from each other, are independently selected from —C 2 F 5  and —C 3 F 7  groups; 
 d′ is an integer comprised between 5 and 250.
   T 1 -O—(CF 2 CF 2 C(Hal) 2 O) e1′—(CF   2 CF 2 CH 2 O) e2′—(CF   2 CF 2 CH(Hal)O) e3′ -T 1′   (4)
 
 
 
       wherein:
 T 1  and T 1′ , equal to or different from each other, have the same meaning as defined above; 
 Hal, equal or different at each occurrence, is a halogen selected from fluorine and chlorine atoms, preferably a fluorine atom; 
 e1′, e2′, and e3′, equal to or different from each other, are independently integers ≧0 such that the (e1′+e2′+e3′) sum is comprised between 5 and 250; should at least two of e1′, e2′ and e3′ be different from zero, the different recurring units are generally statistically distributed along the (per)fluoropolyoxyalkylene chain.
   T 1 -O—[CF(CF 3 )CF 2 O] f1′ (CFYO) f2′-T   1′   (5)
 
 
 
       wherein:
 T 1  and T 1′ , equal to or different from each other, have the same meaning as defined above; 
 Y, equal or different at each occurrence, is selected from a fluorine atom or a —CF 3  group; 
 f1′ and f2′, equal to or different from each other, are independently integers ≧0 such that the f1′/f2′ ratio is comprised between 20 and 1000 and the (f1′+f2′) sum is comprised between 5 and 250; should f1′ and f2′ be both different from zero, the different recurring units are generally statistically distributed along the perfluoropolyoxyalkylene chain.
   T 1 -O—[CF(CF 3 )CF 2 O] g1′ (C 2 F 4 O) g2′ (CFYO) g3′ -T 1 ′  (6)
 
 
 
       wherein:
 T 1  and T 1 ′, equal to or different from each other, have the same meaning as defined above; 
 Y, equal or different at each occurrence, has the same meaning as defined above; 
 g1′, g2′ and g3′, equal to or different from each other, are independently integers ≧0 such that the (g1′+g2′+g3′) sum is comprised between 5 and 250; should at least two of g1′, g2′ and g3′ be different from zero, the different recurring units are generally statistically distributed along the perfluoropolyoxyalkylene chain.
   C 3 F 7 O—[CF(CF 3 )CF 2 O] h′ -T 3   (7)
 
 
 
       wherein:
 T 3  has the same meaning as defined above; 
 h′ is an integer comprised between 5 and 250.
   {C 3 F 7 O—[CF(CF 3 )CF 2 O] i′ —CF(CF 3 )—} 2   (8)
 
 
 
       wherein:
 i′ is an integer comprised between 2 and 250, and
   R 1   f —{C(CF 3 ) 2 —O—[C(R 2   f ) 2 ] j1′ C(R 2   f ) 2 —O} j2′ —R 1   f   (9)
 
 
 
       wherein:
 R 1   f , equal or different at each occurrence, is a C 1 -C 6  perfluoroalkyl group; 
 R 2   f , equal or different at each occurrence, is selected from a fluorine atom and a C 1 -C 6  perfluoroalkyl group; 
 j1′ is equal to 1 or 2; 
 j2′ is an integer comprised between 5 and 250. 
 
     
     
         3 . The lubricant composition of  claim 1 , wherein a mixture of more than one non-functional PFPE oil is used. 
     
     
         4 . The lubricant composition of anyone of  claim 1 , wherein the cyclic phosphazene compound [compound (P)] complies with formula (I-B) or (II-B) here below: 
       
         
           
           
               
               
           
         
       
       wherein:
 R″ f  and R′″ f , equal to or different from each other, independently represent a (per)fluoropolyoxyalkylene chain comprising one or more recurring units selected from the group consisting of: 
 
       (i) —CFYO—, wherein Y is a fluorine atom or a —CF 3  group, 
       (ii) —CF 2 CFYO—, wherein Y has the same meaning as defined above, 
       (iii) —CF 2 CF 2 CF 2 O—, and 
       (iv) —CF 2 CF 2 CF 2 CF 2 O—, 
       said recurring units being generally statistically distributed along the (per)fluoropolyoxyalkylene chain;
 Z and Z′, equal to or different from each other, independently represent a polar group of formula —O − M + , wherein M is selected from hydrogen, a monovalent metal, preferably an alkaline metal, and an ammonium radical having formula —NR 1 R 2 R 3 R 4 , wherein each of R 1 , R 2 , R 3 , R 4  is, independently, a hydrogen atom or a C 1 -C 12  hydrocarbon group, optionally fluorinated, or a polar group of formula —O − ) 2 M′ 2+ , wherein M′ is a divalent metal, preferably an alkaline earth metal; 
 n Z  is an integer comprised between 1 and 3, preferably equal to 1; 
 n Z′  is an integer comprised between 1 and 4, preferably equal to 1; 
 n f  is an integer such that n Z +n f  is equal to 6; 
 n f′  is an integer such that n Z′+n   f′  is equal to 8. 
 
     
     
         5 . The lubricant composition of  claim 4 , wherein the cyclic phosphazene compound [compound (P)] complies with formula (I-B*) or (II-B*) here below: 
       
         
           
           
               
               
           
         
       
       wherein:
 Z, Z′, n z , n z′ , n f  and n f′ , have the same meaning as defined in  claim 4 ; 
 R″* f O— and R′″* f O—, equal to or different from each other, represent a (per)fluoropolyoxyalkylene chain having formula:
   T*-O—(CF 2 CF 2 O) p *(CF 2 O) q —CF 2 —CH 2 —O—(CH 2 CH 2 O) s *—
 
 
 
       wherein:
 T* is selected from —CF 3 , —CF 2 CF 3  and —CF 2 CF 2 CF 3  groups; 
 p* and q* are numbers such that the (p*+q*) sum is comprised between 1 and 50 and the q*/p* ratio is comprised between 0.1 and 10; 
 s* is a number comprised between 0 and 5. 
 
     
     
         6 . The lubricant composition of  claim 4 , wherein the cyclic phosphazene compound [compound (P)] complies with formula (III-B) or (III-B bis) here below: 
       
         
           
           
               
               
           
         
       
       wherein:
 M and M′ have the same meaning as defined in  claim 4 , M being preferably an alkaline metal selected from Li, Na and K or an ammonium radical having formula —NR 1 R 2 R 3 R 4 , wherein each of R 1 , R 2 , R 3 , R 4  is, independently, a hydrogen atom or a C 1 -C 12  hydrocarbon group, preferably R 1 ═R 2 =R 3 ═R 4 =n-butyl, and M′ being preferably an alkaline earth metal selected from Ca and Mg, more preferably M′ being Ca; 
 each of p*i (i=1 to 5) and q*i (i=1 to 5) is independently an integer ≧0 such that the (p*i+q*i) sum is comprised between 2 and 25 and the q*i/p*i ratio is comprised between 0.1 and 10. 
 
     
     
         7 . The lubricant composition of anyone of  claim 1 , wherein the functional PFPE derivative complies with formula (V) here below:
   T-(CFW 1 ) p1 —O—R F —(CFW 2 ) p1′ -T′  (V)
   
       wherein:
 R F  is a (per)fluoropolyoxyalkylene chain (chain R′ F ); 
 T and T′, equal to or different from each other, are selected from: 
 
       i) functional end-groups comprising at least one ether, thioether, ester or amine group comprising at least one monocyclic or polycyclic aromatic ring, said aromatic ring optionally containing one or more heteroatoms selected from N, O and S and one or more substituents different from hydrogen atoms, 
       ii) non-functional end-groups selected from the group consisting of a fluorine atom, a chlorine atom and a C 1 -C 3  (per)fluoroalkyl group optionally containing one or more chlorine atoms, 
       with the proviso that at least one of T and T′ is a functional end-group as defined hereinabove;
 W 1  and W 2 , equal to or different from each other, independently represent a fluorine atom or a —CF 3  group; 
 p1 and p1′, equal to or different from each other, are independently integers comprised between 1 and 3, preferably being equal to 1 when W 1  and/or W 2  are —CF 3  groups. 
 
     
     
         8 . The lubricant composition of  claim 7 , wherein the functional PFPE derivative complies with formula (VI) here below:
   T″-CF 2 O(CF 2 CF 2 O) m *(CF 2 O) n *CF 2 -T′″  (VI)
   
       wherein:
 T″ and T′″, equal to or different from each other, are selected from: 
 
       i) functional end-groups selected from those having formulae —CH 2 -A-Y, —CH(CF 3 )-A-Y, —CHW′—B—(CH 2 CH 2 O) m′ —Y and —COOY, wherein: 
       (a′) A is selected from oxygen and sulphur atoms, 
       (b′) B is selected from an oxygen atom, a sulphur atom and a —NH group, 
       (c′) W′ is selected from a hydrogen atom and a —CF 3  group, 
       (d′) m′ is an integer comprised between 0 and 6, 
       (e′) Y is selected from phenyl, pyridine, triazine, benzoxazole, benzothiazole and benzopyrazine groups optionally substituted with one or more substituents different from hydrogen atoms, 
       ii) non-functional end-groups selected from the group consisting of a fluorine atom, a chlorine atom, a —CF 3  group, a —C 2 F 5  group and a —(CF 2 ) n Cl group, wherein n is an integer comprised between 1 and 3, 
       with the proviso that at least one of T″ and T′″ is a functional end-group as defined hereinabove;
 m* and n* are integers such that the number average molecular weight of the functional PFPE derivative is comprised between 400 and 10000, the m*/n* ratio being comprised between 0.1 and 10. 
 
     
     
         9 . The lubricant composition of anyone of  claim 1 , wherein at least one cyclic phosphazene compound [compound (P)] is comprised in an amount ranging from 0.3% to 5% by weight with respect to the weight of the non-functional PFPE oil and at least one functional PFPE derivative different from compound (P) is comprised in an amount ranging from 2% to 6% by weight with respect to the weight of the non-functional PFPE oil. 
     
     
         10 . A method for lubricating vacuum pumps comprising the use of the lubricant composition of  claim 1 .