Use of an oligomer-based additive for stabilizing a lubricating composition for a conveyor chain

1. A lubricating composition, comprising:

a base oil and an additive,

the additive comprising a mixture of oligomers that is produced from the reaction of aromatic amines selected from the group consisting of:

(i) the reaction of diphenylamine (DPA) compounds with each other, the (DPA) compounds having the formula (I):

wherein R 1 and R 2 represent, independently of one another, a hydrogen or a linear or branched alkyl group having from 1 to 30 carbon atoms,

(ii) the reaction of phenyl-α-naphthylamine (PAN) compounds with each other, in the presence of potassium permanganate catalyst, the (PAN) compounds having the formula (II):

wherein the group R 3 represents a hydrogen or a linear or branched alkyl group having from 1 to 30 carbon atoms, and

(iii) the reaction of a (DPA) compound of formula (I) with a (PAN) compound of formula (II), in the presence of potassium permanganate catalyst,

said reaction producing an additive comprising:

I) (a) from 0% to 3% by weight of diphenylamine of formula (I),

(b) from 0% to 3% by weight of phenyl-α-naphthylamine of formula (II),

(c) from 1% to 40% by weight of oligomers in the form of dimers,

(d) from 25% to 45% by weight of oligomers in the form of trimers,

(e)from 20% to 45% by weight of oligomers in the form of tetramers,

(f) from 1% to 25% by weight of oligomers in the form of pentamers,

(g) from 0% to 10% by weight of oligomers in the form of hexamers, and

(h) from 0% to 10% by weight of oligomers in the form of heptamers or oligomers with a higher degree of polymerization,

wherein the percentages by weight are expressed relative to the total weight of the (a)-(h) components;

or an additive comprising:

(II) (a) from 0% to 1% by weight of diphenylamine of formula (I),

(b) from 0% to 1% by weight of phenyl-α-naphthylamine of formula (II),

(c) from 1% to 5% by weight of oligomers in the form of dimers,

(d) from 30% to 45% by weight of oligomers in the form of trimers,

(e) from 20% to 35% by weight of oligomers in the form of tetramers,

(f) from 10% to 30% by weight of oligomers in the form of pentamers,

(g) from 0% to 15% by weight of oligomers in the form of hexamers, and

(h) from 0% to 10% by weight of oligomers in the form of heptamers or oligomers with a higher degree of polymerization,

wherein the percentages by weight are expressed relative to the total weight of the (a)-(h) components.

2. The lubricating composition according to claim 1 , wherein in formula (I), each of R 1 and R 2 represents an octyl group.

3. The lubricating composition according to claim 1 , wherein in formula (II), R 3 is an octyl group or an hydrogen atom.

4. The stabilized lubricating composition according to claim 1 , wherein said base oil is a mineral oil or a synthetic ester-based oil.

5. The stabilized lubricating composition according to claim 1 , wherein said additive is present in the lubricating composition in an amount of 0.1% to 10% by weight, relative to the total weight of the lubricating composition.

6. A method for stabilizing a lubricating composition for a conveyor chain subjected to a temperature of at least 120° C., comprising:

adding to said lubricating composition an additive comprising a mixture of oligomers that is produced from the reaction of aromatic amines selected from the group consisting of:

(i) the reaction of diphenylamine(DPA) compounds with each other, said (DPA) compounds having the formula (I):

wherein R 1 and R 2 represent, independently of one another, a hydrogen of a linear or branched alkyl group having from 1 to 30 carbon atoms,

(ii) the reaction of phenyl-α-naphthylamine (PAN) compounds with each other, in the presence of potassium permanganate catalyst, said (PAN) compounds having the formula (II):

wherein R 3 represents a hydrogen or a linear or branched alkyl group having from 1 to 30 carbon atoms, and

(iii) the reaction of a (DPA) compound of formula (I) with a (PAN) compound of formula (II), in the presence of potassium permanganate catalyst,

said reaction producing an additive comprising:

I) (a) from to weight of diohenylamine of formula (I),

(b) from 0% to 3% by weight of phenyl-α-naphthylamine of formula (II),

(c) from 1% to 40% by weight of oligomers in the form of dimers,

(d) from 25% to 45% by weight of oliqomers in the form of trimers,

(e) from 20% to 45% by weight of oligomers in the form of tetramers,

(f) from 1% to 25% by weight of oligomers in the form of pentamers,

(g) from 0% to 10% by weight of oligomers in the form of hexamers, and

(h) from 0% to 10% by weight of oligomers in the form of heptamers or oligomers with a higher degree of polymerization,

wherein the percentages by weight are expressed relative to the total weight of the (a)-(h) components;

or an additive comprising:

(II) from 0% to 1% by weight of diphenylamine of formula (I),

(b) from 0% to 1% by weight of phenyl-α-naphthylamine of formula (II),

(c) from 1% to 5% by weight of oligomers in the form of dimers,

(d) from 30% to 45% by weight of oligomers in the form of trimers,

(e) from 20% to 35% by weight of oligomers in the form of tetramers,

(f) from 10% to 30% by weight of oligomers in the form of pentamers,

(g) from 0% to 15% by weight of oligomers in the form of hexamers, and

(h) from 0% to 10% by weight of oligomers in the form of heptamers or oligomers with a higher degree of polymerization,

wherein the percentages by weight are expressed relative to the total weight of the (a)-(h) components.

7. The method according to claim 6 , wherein for the diphenylamine (DPA) compound of formula (I), each of R 1 and R 2 represents an octyl group.

8. The method according to claim 6 , wherein for the phenyi-α-naphthylamine (PAN) compound of formula (II), R 3 is an octyl group or an hydrogen atom.

9. The method according to claim 6 , wherein said lubricating composition is a mineral oil or a synthetic ester-based oil.

10. The method according to claim 6 , wherein the lubricating composition is suitable for lubricatinq a conveyer chain subjected to a temperature of at least 150° C.

11. The method according to claim 6 , wherein said additive present in the lubricating ccmposition in an amount of 0.1% to 10% by weight, relative to the total weight of the lubricating composition.

12. The method according to claim 6 , wherein the additive is produced by reaction (i) the reaction of diphenyiamine (DPA) compounds with each other, and the reaction produces an additive comprising:

(a) from 0% to 30% by weight of diphenylamine of formula (I),

(b) from 0% to 1% by weight of phenyl-α-naphthylamine of formula (II),

(c) from 1% to 95% by weight of oligomers in the, form of dimers of DPA,

(d) from 0% to 35% by weight of oligomers in the form of trimers of DPA,

(e) from 0% to 35% by weight of oligomers in the form of tetramers of DPA

(f) from 0% to 30% by weight of oligomer in the form of pentamers of(DPA),

(g) from 0% to 10% by weight of oligomers in the form of hexamers of DPA, and

(h) from 0% to 10% by weight of oligomers in the form of heptamers of DPA or oligomers with a higher degree of polymerization,

wherein the percentages by weight are expressed relative to the total weight of the (a)-(h) components.

13. The method accordinq to claim 6 , wherein in formulae (I) and (II), R 1 , R 2 and R 3 independently represent a hydrogen or a linear or branched alkyl group having from 4 to 12 carbon atoms.

14. The lubricating composition according to claim 1 , wherein in formulae (I) and (II), R 1 , R 2 and R 3 independently represent a hydrogen or a linear or branched alkyl group having from 4 to 12 carbon atoms.