Lubricants for refrigeration systems

Abstract

A lubricating composition which comprises: (A) a polyalkyleneglycol of the general formula (I): RO(R a O) x (R b O) y (R c O) z R d   (I) wherein: R is a C 4 to C 6 substituent comprising a heterocyclic ring, in which the heteroatom(s) in said ring(s) is (are) oxygen and/or sulphur, R a is a C 2 alkylene group, R b is a C 3 alkylene group, R c is a C 4 alkylene group, R d is the same as R, or is a hydrogen atom or a C 1 -C 20 alkyl or C 1 -C 20 acyl group, x, y, z are each independently 0 or an integer in the range of from 1 to 100, and x+y+z=4 to 100; and (B) an ester of a alcohol containing two or more hydroxyl groups with a mono- or dicarboxylic acid, or an ester of an dicarboxylic acid with an alcohol containing one hydroxyl group.

1 . A lubricating composition which comprises: 
 (A) a polyalkyleneglycol of the general formula (I):      RO(R a O),(R b O) y (R c O) z R d    (I)    wherein:    R is a C 4  to C 6  substituent comprising a heterocyclic ring, in which the heteroatom(s) in said ring(s) is (are) oxygen and/or sulphur,    R a  is a C 2  alkylene group,    R b  is a C 3  alkylene group,    R c  is a C 4  alkylene group,    R d  is the same as R, or is a hydrogen atom or a C 1 -C 20  alkyl or C 1 -C 20  acyl group,    x, y, z are each independently 0 or an integer in the range of from 1 to 100, and    X+y+z=4 to 100; and    (B) an ester of a alcohol containing two or more hydroxyl groups with a mono- or dicarboxylic acid, or an ester of an dicarboxylic acid with an alcohol containing one hydroxyl group.    
   
   
       2 . A composition as claimed in  claim 1 , in which R represents a 5-membered oxygen-containing heterocycle linked to the rest of the molecule either directly or via a CH 2  group.  
   
   
       3 . A composition as claimed in  claim 2 , in which R represents a tetrahydrofurfuryl group.  
   
   
       4 . A composition as claimed in  claim 1 , in which either z is 0 or z and x are both 0.  
   
   
       5 . A composition as claimed in  claim 1 , in which the sum of x, y and z is equal to a number in the range of from 5 to 80.  
   
   
       6 . A composition as claimed in  claim 1 , in which R d  represents a hydrogen atom or a C 1-4  alkyl group.  
   
   
       7 . A composition as claimed in  claim 6 , in which R d  represents a methyl group.  
   
   
       8 . A composition as claimed in  claim 1 , in which the compound of the formula I has the formula Ia:  
       R 1 O—(R 2 O) m —R 3    (Ia)  in which R 1  is a tetrahydrofurfuryl group; R 2  is a mix of C 2  and C 3  alkylene groups, the number ratio of C 2  to C 3  groups preferably being in the range of from 27:75 to 75:25, or R 2  is a C 3  alkylene group; m is from 5 to 80; and R 3  is a hydrogen atom or a C 1-4  alkyl group.    
   
   
       9 . A composition as claimed in  claim 1 , in which the acid from which the ester component (B) is derived is an alkanoic or alkandioic acid, and the alcohol is a mono-, di- or poly-hydroxyl alkanol.  
   
   
       10 . A composition as claimed in  claim 9 , in which the ester is an ester of neopentyl glycol, monopentaerythritol, dipentaerythritol and/or trimethylolpropane with a C 2-18  mono- or di-alkanoic acid.  
   
   
       11 . A composition as claimed in  claim 10 , in which the ester is an ester of neopentyl glycol and/or monopentaerythritol with a C 2-10  mono alkanoic acid or a C 6  dialkanoic acid, or a dipentaerythritol ester of a C 2-10  mono alkanoic acid or a C 8-9  dialkanoic acid.  
   
   
       12 . A composition as claimed in  claim 11 , in which the ester is an ester of monopentaerythritol with a C 5-9  mono alkanoic acid or a C 6  dialkanoic acid.  
   
   
       13 . A refrigerant composition for refrigeration apparatus which comprises a lubricant composition comprising: 
 (A) a polyalkyleneglycol of the general formula (I):      RO(R a O) x (R b O) y (R c O) z R d    (I)    wherein:    R is a C 4  to C 6  substituent comprising a heterocyclic ring, in which the heteroatom(s) in said ring(s) is (are) oxygen and/or sulphur,    R a  is a C 2  alkylene group,    R b  is a C 3  alkylene group,    R c  is a C 4  alkylene group,    R d  is the same as R, or is a hydrogen atom or a C 1 -C 20  alkyl or C 1 -C 20  acyl group,    x, y, z are each independently 0 or an integer in the range of from 1 to 100, and    X+y+z=4 to 100; and    (B) an ester of a alcohol containing two or more hydroxyl groups with a mono- or dicarboxylic acid, or an ester of an dicarboxylic acid with an alcohol containing one hydroxyl group;    together with a refrigerant.    
   
   
       14 . A refrigerant composition as claimed in  claim 13 , in which the refrigerant is selected from fluorocarbons, hydrofluorocarbons, hydrocarbons, ammonia, and carbon dioxide.  
   
   
       15 . A refrigerant composition as claimed in  claim 14 , in which the refrigerant is selected from 1,1,1,2-tetrafluoroethane or carbon dioxide.  
   
   
       16 . Refrigeration apparatus which includes a refrigerant composition which comprises: 
 (A) a polyalkyleneglycol of the general formula (I):      RO(R a O) x (R b O) y (R c O) z R d    (I)    wherein:    R is a C 4  to C 6  substituent comprising a heterocyclic ring, in which the heteroatom(s) in said ring(s) is (are) oxygen and/or sulphur,    R a  is a C 2  alkylene group,    R b  is a C 3  alkylene group,    R c  is a C 4  alkylene group,    R d  is the same as R, or is a hydrogen atom or a C 1 -C 20  alkyl or C 1 -C 20  acyl group,    x, y, z are each independently 0 or an integer in the range of from 1 to 100, and    X+y+z=4 to 100; and    (B) an ester of a alcohol containing two or more hydroxyl groups with a mono- or dicarboxylic acid, or an ester of an dicarboxylic acid with an alcohol containing one hydroxyl group;    together with a refrigerant.    
   
   
       17 . A composition as claimed in  claim 8 , in which the acid from which the ester component (B) is derived is an alkanoic or alkandioic acid, and the alcohol is a mono-, di- or poly-hydroxyl alkanol.  
   
   
       18 . A composition as claimed in  claim 17 , in which the ester is an ester of neopentyl glycol, monopentaerythritol, dipentaerythritol and/or trimethylolpropane with a C 2-18  mono- or di-alkanoic acid.  
   
   
       19 . A composition as claimed in  claim 18 , in which the ester is an ester of neopentyl glycol and/or monopentaerythritol with a C 2-10  mono alkanoic acid or a C 6  dialkanoic acid, or a dipentaerythritol ester of a C 2-10  mono alkanoic acid or a C 8-9  dialkanoic acid.  
   
   
       20 . A composition as claimed in  claim 19 , in which the ester is an ester of monopentaerythritol with a C 5-9  mono alkanoic acid or a C 6  dialkanoic acid.