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, said lubricating composition comprising:

a thermoplastic matrix; and

at least one braking additive;

wherein the thermoplastic matrix is an aqueous emulsion comprising:

polyethylene emulsion

 0 to 50 wt %

acrylic emulsion

10 to 80 wt %

calcium sulphonate derivative

 1 to 40 wt %

alkyl polymethacrylate

 1 to 40 wt %

zinc stearate emulsion

10 to 50 wt %,

the at least one 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 said tubular threaded joint, and

the at least one braking additive is selected from the group consisting of bismuth oxide, titanium oxide, a colloidal silica, an acrylic polymer and carbon black,

the at least one braking additive is dispersed in the thermoplastic matrix and

the at least one braking additive is selected 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.

2. The film-forming lubricating composition according to claim 1 wherein the braking additive composition is carbon black alone.

3. The film-forming lubricating composition according to claim 1 wherein the at least one braking additive is pyrogenic spherular colloidal silica.

4. The film-forming lubricating composition according to claim 1 , further comprising particles of at least one solid lubricant which are dispersed in the thermoplastic matrix with the at least one braking additive.

5. The film-forming lubricating composition according to claim 4 wherein said particles of at least one solid lubricant comprise particles of lubricants of at least one of the classes 1, 2, 3 and 4.

6. The film-forming lubricating composition according to claim 5 wherein the particles of the at least one solid lubricant comprise particles of at least one solid lubricant of class 2 and at least one solid lubricant of class 1.

7. The film-forming lubricating composition according to claim 5 wherein the particles of the at least one solid lubricant comprise particles of at least one solid lubricant of class 2 and at least one solid lubricant of class 4.

8. The film-forming lubricating composition according to claim 5 wherein the particles of the at least one solid lubricant 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.

9. The film-forming lubricating composition according to claim 5 wherein the particles of the at least one solid lubricant comprise at least particles of at least one solid lubricant of class 1 selected from zinc oxide and boron nitride.

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

11. The film-forming lubricating composition according to claim 5 wherein the particles of the at least one solid lubricant comprise at least particles of polytetrafluoroethylene as a solid lubricant of class 4.

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

13. The film-forming lubricating composition according to claim 1 wherein the thermoplastic matrix is of a solid consistency, not sticky to the touch and has a plastic rheological behaviour or a viscoplastic rheological behaviour.

14. The film-forming lubricating composition according to claim 13 wherein a melting point of the thermoplastic matrix is between 80° C. and 400° C.

15. The film-forming lubricating composition according to claim 13 wherein the thermoelastic matrix comprises at least one binder with viscoelastic behaviour.

16. The film-forming lubricating composition according to claim 1 wherein the thermoelastic matrix further comprises at least one wax of vegetable, animal, mineral or synthetic origin.

17. The film-forming lubricating composition according to claim 1 wherein the thermoelastic matrix further at least one corrosion inhibitor.

18. The film-forming lubricating composition according to claim 17 wherein the at least one corrosion inhibitor is selected from the group consisting of a calcium sulphonate and a calcium oxydate.

19. The film-forming lubricating composition according to claim 1 wherein the thermoelastic matrix further comprises at least one liquid polymer of a kinematic viscosity at 100° C. which is at least equal to 850 mm 2 /s.

20. The film-forming lubricating composition according to claim 19 wherein said liquid polymer is selected from the group consisting of an alkyl polymethacrylate, a polybutene, a polyisobutene and a polydialkylsiloxane.

21. The film-forming lubricating composition according to claim 1 wherein the thermoplastic matrix further comprises at least one colouring agent.

22. The film-forming lubricating composition according to claim 1 wherein the thermoelastic matrix further comprises at least one surface-active agent,

wherein the surface active agent promotes bonding to the surface and homogeneity of the coating.

23. The film-forming lubricating composition according to claim 1 wherein the thermoelastic matrix further comprises at least one anti-oxidant.

24. The film-forming lubricating composition according to claim 4 wherein the solid lubricant comprises: 65 to 99 wt % graphite fluoride and 1 to 35 wt % zinc oxide.

25. The film-forming lubricating composition according to claim 4 wherein the solid lubricant comprises:

20 to 99 wt %

graphite fluoride;

 0 to 30 wt %

boron nitride; and

 1 to 80 wt %

polytetrafluoroethylene.

26. The film-forming lubricating composition according to claim 4 wherein the solid lubricant comprises:

20 to 99 wt %

tin sulphides;

 0 to 30 wt %

boron nitride; and

 1 to 80 wt %

polytetrafluoroethylene.

27. The film-forming lubricating composition according to claim 4 wherein the solid lubricant comprises:

20 to 99 wt %

bismuth sulphides;

 0 to 30 wt %

boron nitride; and

 1 to 80 wt %

polytetrafluoroethylene.

28. The film-forming lubricating composition according to claim 4 , comprising:

45 to 93 wt % of the thermoplastic matrix;

1 to 25 wt % of the at least one solid lubricant; and

5 to 20 wt % of the at least one braking additive.

29. The film-forming lubricating composition according to claim 1 wherein the thermoplastic matrix is of pasty consistency and further comprises at least one extreme-pressure additive with a chemical action.