Method for placing a self-sealing product on the inner surface of a tire

Patent metadata

Field	Value
Publication number	US-10730255-B2
Application number	US-201515310672-A
Country	US
Kind code	B2
Filing date	May 7, 2015
Priority date	May 13, 2014
Publication date	Aug 4, 2020
Grant date	Aug 4, 2020

Abstract

The process includes a non-crosslinked self-sealing composition which is introduced into an extrusion means, the geometric and thermodynamic characteristics of which have been specially adapted. The speed and temperature conditions of the extrusion means are adjusted so that, at an application nozzle forming the outlet die of the extrusion means, the self-sealing composition is crosslinked. The application nozzle is brought close to the internal surface of the casing previously set in relative motion with respect to the application nozzle, and an extruded and crosslinked bead that has a given width and profile is deposited directly on the internal surface of the casing.

First claim

The invention claimed is:

1. A method of applying a rubber-based self-sealing composition on an inner surface of a tire casing, comprising the steps of:
introducing a non-crosslinked self-sealing composition into an extrusion device
adjusting speed and temperature conditions of the extrusion device so that, at an application nozzle forming an outlet die of said extrusion device, the self-sealing composition is crosslinked, and
bringing the application nozzle close to the inner surface of said casing previously set in relative motion with respect to the application nozzle, and depositing an extruded and crosslinked bead having a given width and profile directly on said internal surface of the casing.

2. The method according to claim 1 , in which the value of the G″/G′ (Tg δ) ratio of the self-sealing composition decreases by a value greater than 0.1 when it changes from the non-crosslinked state to the crosslinked state.

3. The method according to claim 2 , in which the value of the G″/G′ (Tg δ) ratio of the non-crosslinked self-sealing composition is between 1.2 and 3.

4. The method according to claim 2 , in which the value of the G″/G′ (Tg δ) ratio of the crosslinked self-sealing composition is between 0.66 and 2.

5. The method according to claim 1 , in which the properties of shear thinning and of reducing the viscosity as a function of the temperature of the self-sealing composition are combined with the method of supplying heat so as to control the integrity of the elastomeric matrix during crosslinking in the extruder.

6. The method according to claim 1 , in which the extrusion device is formed by a screw of length (L) and of diameter (D) rotated inside a barrel.

7. The method according to claim 6 , in which the ratio (L/D) between the length and the diameter of the screw is between 15 and 30.

8. The method according to claim 1 , in which the temperature and speed conditions of the extrusion means are adjusted so that the composition remains inside the extrusion device at a temperature between 150° C. and 200° C. for a time of between 1 min and 20 min.

9. The method according to claim 1 , in which the temperature and speed conditions of the extrusion device are adjusted so that the amount of thermal energy supplied to the self-sealing composition in the form of mechanical energy is less than 75% of the total thermal energy supplied to said self-sealing composition.

10. The method according to claim 1 , in which the output speed of the self-sealing composition from the application nozzle is between 1 ms −1 and 4 ms −1 .

11. The method according to claim 1 , in which the self-sealing composition is deposited by coiling said bead by varying the pitch and the axial position of the application nozzle with respect to the tire casing.

12. The method according to claim 11 , in which said bead is applied continuously by moving the application nozzle tangentially to the internal surface of the tire from the equator of the casing to a first shoulder, then by starting again in the opposite direction in the direction of a second opposite shoulder passing through the equator, and by finally coming back to the equator.

13. The method according to claim 1 , in which the tire casing is in the vulcanized state.

14. A method of applying a rubber-based self-sealing composition on an inner surface of a tire casing, comprising the steps of:
introducing a non-crosslinked self-sealing composition into an inlet of an extrusion device;
adjusting speed and temperature conditions of the extrusion device so that, at an application nozzle forming an outlet die of said extrusion device, the self-sealing composition is crosslinked, and
bringing the application nozzle close to the inner surface of said casing previously set in relative motion with respect to the application nozzle, and depositing an extruded and crosslinked bead having a given width and profile directly on said internal surface of the casing;
wherein the extrusion device includes an assembly comprising a screw rotated in a barrel, the extrusion device further including a duct positioning downstream of the assembly that opens into the application nozzle;
wherein the extrusion device includes a plurality of zones, and the method further includes increasing the temperature of the composition in a first zone to a set point temperature between 140 degrees C. and 220 degrees C. during a first period of time, maintaining the temperature at the set point temperature in a second zone for a second period of time, and increasing the temperature in a third zone for a third period of time, wherein the third period of time is shorter relative to the second period of time;
wherein the third zone includes the duct and the application nozzle.

15. The method of claim 14 , wherein the application nozzle is axially moveable, and the bead is deposited in a coiled manner relative to the tire casing.

16. The method of claim 14 , wherein the self-sealing composition is pre-mixed at a ratio of material and the ratio of material is maintained from the inlet to the outlet die.

Assignees

• Michelin & Cie
• Michelin Rech Tech

Inventors

• Barjon Stephane
• Beldent Christian
• Dussardier Bruno
• Joandel Sarah

Classifications

• B29D2030/0686

  Incorporating sealants on or into tyres not otherwise provided for; auxiliary operations therefore, e.g. preparation of the tyre · CPC title

• B29C48/2526

  Direct drives or gear boxes · CPC title

• B29C48/155

  Partial coating thereof · CPC title

• B29C2948/92695

  Viscosity; Melt flow index [MFI]; Molecular weight · CPC title

• B29D2030/0694

  the sealant being in the form of one or more narrow strips, e.g. applied by winding into the interior of the tyre · CPC title