Lubricating composition with an adaptable coefficient of friction, for a threaded element of a component of a tubular threaded joint

1. A film-forming lubricating composition for make up of threaded joints suitable for covering at least one thread and a screwing abutment of a threaded element of a component of a tubular threaded joint with a film in the solid state which is adhesive to said thread and said screwing abutment, said screwing abutment being intended to bear against another abutment of another component of said tubular threaded joint in the terminal make up phase and said lubricating composition comprising:

i) a solid lubricant;

ii) a matrix, comprising in % by weight of the matrix:

5 to 96% polyethylene homopolymer;

2 to 30% carnauba wax;

2 to 30% zinc stearate;

0 to 50% of a calcium sulphonate derivative;

0 to 15% alkyl polymethacrylate;

0 to 1% coloring agent; and

0 to 1% anti-oxidant; and

iii) a braking additive which is dispersed in the matrix and selected in order to impart to the composition, in addition to lubrication, a coefficient of friction selected in such a way as to obtain a torque on shoulder resistance value which is at least equal to a threshold value,

wherein the braking additive is arranged to allow a torque on shoulder resistance value to be obtained which is at least equal to a threshold value equal to 100% of a torque on shoulder resistance reference value of a grease of type API RP 5A3 obtained for the tubular threaded joint,

wherein the braking additive is selected from the group consisting of bismuth oxide, titanium oxide, colloidal silica, acrylic polymers and carbon black,

wherein the matrix is of a solid consistency, not sticky to the touch, and

particles of the solid lubricant are dispersed in the matrix with the braking additive.

2. The lubricating composition according to claim 1 wherein the composition comprises by weight of braking additives:

bismuth trioxide 25 to 99%, and

titanium dioxide 1 to 75%.

3. The lubricating composition according to claim 1 wherein the braking additive consists of carbon black.

4. The lubricating composition according to claim 1 wherein the braking additive consists of pyrogenic spherular colloidal silica.

5. The lubricating composition according to claim 1

wherein said particles of solid lubricant or lubricants comprise particles of lubricants of at least one of the classes 1, 2, 3 and 4.

6. The lubricating composition according to claim 1 , comprising, by weight:

45 to 93% thermoplastic matrix;

1 to 25% solid lubricant or lubricants; and

5 to 20% braking additive or additives.

7. The lubricating composition according to claim 5 wherein the particles of solid lubricant or lubricants comprise particles of at least one solid lubricant of class 2 and at least one solid lubricant of class 1.

8. The lubricating composition according to claim 5 wherein the particles of solid lubricant or lubricants comprise particles of at least one solid lubricant of class 2 and at least one solid lubricant of class 4.

9. The lubricating composition according to claim 5 wherein the particles of solid lubricant or lubricants comprise particles of at least one solid lubricant of class 1, at least one solid lubricant of class 2 and at least one solid lubricant of class 4.

10. The lubricating composition according to claim 5 wherein the particles of solid lubricant or lubricants comprise at least particles of at least one solid lubricant of class 1 selected from zinc oxide and boron nitride.

11. The lubricating composition according to claim 5 wherein the particles of solid lubricant or lubricants comprise particles of at least one solid lubricant of class 2 selected from graphite fluoride, tin sulphides, bismuth sulphides and tungsten disulphide.

12. The lubricating composition according to claim 5 wherein the particles of solid lubricant or lubricants comprise at least particles of polytetrafluoroethylene as a solid lubricant of class 4.

13. The lubricating composition according to claim 5 wherein the particles of solid lubricant or lubricants comprise at least molecules of at least one fullerene of spherical or tubular geometry.

14. The lubricating composition according to claim 1 wherein said matrix comprises at least one thermosetting binder.

15. The lubricating composition according to claim 14 wherein said thermosetting binder is selected from a group comprising at least epoxy resins, polyurethane, silicone, alkyd urethane and formophenolic resins.

16. The lubricating composition according to claim 1 wherein said matrix comprises at least one mineral binder.

17. The lubricating composition according to claim 1 wherein said matrix comprises at least one binder of chelate type.

18. The lubricating composition according to claim 1 wherein said matrix is of solid consistency and not sticky to the touch and comprises at least one binder with a viscoelastic behavior.

19. The lubricating composition according to claim 1 wherein said matrix further comprises at least one metallic soap.

20. The lubricating composition according to claim 19 wherein the soap is at least one selected from the group consisting of zinc stearate, calcium stearate, lithium stearate, aluminium stearate and bismuth stearate.

21. The lubricating composition according to claim 1 wherein said matrix further comprises at least one wax of vegetable, animal, mineral or synthetic origin.

22. The lubricating composition according to claim 1 wherein said matrix further comprises at least one corrosion inhibitor.

23. The lubricating composition according to claim 22 wherein the corrosion inhibitor is at least one selected from the group consisting of one derivative of calcium sulphonate and a calcium oxydate.

24. The lubricating composition according to claim 1 wherein said matrix comprises at least one liquid polymer of a kinematic viscosity at 100° C. which is at least equal to 850 mm 2 /s.

25. The lubricating composition according to claim 24 wherein said liquid polymer is at least one selected from the group consisting of an alkyl polymethacrylate, a polybutene, a polyisobutene and a polydialkylsiloxane.

26. The lubricating composition according to claim 1 wherein said matrix further comprises at least one colouring agent.

27. The lubricating composition according to claim 1 wherein said matrix comprises at least one surface-active agent intended to promote bonding to the surface and homogeneity of the coating.

28. The lubricating composition according to claim 1 wherein said matrix further comprises at least one anti-oxidant.

29. The lubricating composition according to claim 5 wherein the composition by weight of solid lubricants is:

65 to 99% graphite fluoride; and

1 to 35% zinc oxide.

30. The lubricating composition according to claim 5 wherein the composition by weight of solid lubricants is:

20 to 99% graphite fluoride;

0 to 30% boron nitride; and

1 to 80% polytetrafluoroethylene.

31. The lubricating composition according to claim 5 wherein the composition by weight of solid lubricants is:

20 to 99% tin sulphides;

0 to 30% boron nitride; and

1 to 80% polytetrafluoroethylene.

32. The lubricating composition according to claim 1 wherein the composition by weight of solid lubricants is:

20 to 99% bismuth sulphides;

0 to 30% boron nitride; and

1 to 80% polytetrafluoroethylene.

33. The lubricating composition according to claim 1 wherein said matrix is of pasty consistency and comprises at least one extreme-pressure additive with a chemical action.

34. The threaded element of a component of a tubular threaded joint, said threaded element comprising at least one thread and a screwing abutment against which another abutment of another component of said tubular threaded joint is to bear at the end of make up, wherein at least said thread and said screwing abutment are covered with a thin layer which adheres to the surface of the thread and the screwing abutment and is formed by the lubricating composition according to claim 1 .

35. The threaded element according to claim 34 wherein a thickness of the lubricating composition layer is between 10 μm and 50 μm.

36. The threaded element according to claim 34 , further comprising a sealing surface capable of being in sealing tightening contact with a corresponding sealing surface of another threaded element after said make up operation, and covered with said lubricating composition.

37. The threaded element according to claim 34 wherein said screwing abutment is an annular abutment surface.

38. The threaded element according to claim 34 wherein the surfaces covered by the lubricating composition have geometrical, physical and/or chemical characteristics for adsorbing or absorbing said lubricating composition.

39. The threaded element according to claim 34 wherein the surfaces are previously coated with a coating or film having a function of protection against corrosion.

40. A tubular threaded joint comprising a male threaded element and a female threaded element wherein one at least of said threaded elements is in accordance with claim 34 .