Method for applying to the inner wall of a tire

Abstract

A process for applying particles to the inner wall of a tire comprising two sidewalls, a crown provided radially externally with a tread, a carcass-type reinforcing structure and at least one crown reinforcement, the inner surface of the sidewalls and of the crown forming an inner wall, at least one portion of said inner wall being covered with at least one layer of self-sealing composition. The particles are applied after the curing of the tire.

Claims

1. A process for applying particles to an inner wall of a tire comprising two sidewalls, a crown provided radially externally with a tread, a carcass-type reinforcing structure and at least one crown reinforcement, an inner surface of the sidewalls and of the crown forming an inner wall, at least one portion of said inner wall being covered with at least one layer of self-sealing composition, comprising applying the particles, after the curing of the tire, to the layer of self-sealing composition by a flocking technique, wherein the particles are comprised of tire grindings.

2. The process according to claim 1, wherein the flocking technique is carried out by spraying under pressure.

3. The process according to claim 1, wherein a shape of the particles is defined by a ratio L/E of greater than 3, where L represents the length or largest dimension of the particle and E represents the mean thickness of the particle.

4. The process according to claim 1, wherein the particles have a mean diameter of between 0.2 and 5 mm.

5. The process according to claim 1, wherein the particles have any geometric shape.

6. The process according to claim 1, wherein the particles have a monochromatic yellow colour.

7. The process according to claim 1, wherein the applied particles establish a particle layer having a mean thickness of between 0.1 and 0.5 mm.

8. The process according to claim 1, wherein the particles cover between 60% and 95% of the inner wall.

9. The process according to claim 1, wherein the tire grindings comprise reinforcing threads.

Description

BRIEF DESCRIPTION OF DRAWING

(1) The invention will now be described with the aid of the sole FIGURE and exemplary embodiments that follow, and which are given solely by way of illustration.

(2) The sole FIGURE represents, in cross-section, a tire according to an embodiment of the invention provided on its inner surface with a layer of particles.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(3) As can be seen in this FIGURE, the tire of general reference 1 comprises a crown 2 reinforced by two crown reinforcements or belt 6, two sidewalls 3 and two beads 4, each of these beads 4 being reinforced with a bead wire 5. The crown 2 is surmounted by a tread (not shown). A carcass reinforcement 7 is wound around two bead wires 5 in each bead 4, the upturn 8 of this reinforcement 7 lying for example towards the outside of the tire 1 which is shown here fitted on its rim 9. The carcass reinforcement 7 consists, as is known per se, of at least one ply reinforced by cords referred to as radial cords, for example textile or metal cords, i.e. these chords are arranged practically parallel to one another and extend from one bead to the other so as to form an angle of between 80 and 90 with the circumferential mid-plane (plane perpendicular to the axis of rotation of the tire, which is located at mid-distance between the two beads 4 and passes through the middle of the crown reinforcement 6).

(4) The inner wall of the tire 1 comprises a layer 10 of self-sealing composition on which a layer 11 of coloured cellulose fibre particles is arranged. In the present case, the fibres are yellow-coloured.

(5) The layer 11 of particles, covering the layer 10 of self-sealing composition, preferably covers the inner wall corresponding to the crown 2 and to the shoulders 12 of the tire.

(6) The cellulose fibres applied to the inner wall of the tire have a mean dimension of around 2 mm, and have any geometric shape.

(7) The self-sealing composition may be an elastomer composition comprising at least a diene elastomer, a hydrocarbon resin and a liquid plasticizer. Besides various optional additives, it may or may not comprise a crosslinking agent and/or a small fraction of reinforcing filler. This self-sealing composition is described in application WO 2011/092179 A1.

(8) The self-sealing composition may also be a composition comprising a blend of at least two solid elastomers, a polybutadiene or butadiene copolymer elastomer (compound A), a natural rubber or synthetic polyisoprene elastomer (compound B), the weight ratio A/B being between 10/90 and 90/10, a hydrocarbon resin, optionally with a filler as described in applications WO 2011/092122 and WO 2011/092123.

(9) The self-sealing composition may also be a composition comprising a styrene thermoplastic elastomer as described in patent FR 2,917,996 or else a styrene thermoplastic elastomer and an extender oil as described in application WO 2008/080557.

(10) The self-sealing composition may also be a multilayer laminate comprising a first layer of polystyrene/polyisobutylene block copolymer thermoplastic elastomer, and a second elastomer layer based on a styrene thermoplastic elastomer, identical to or different from the first. The first layer optionally comprises an extender oil, and the second comprises an extender oil as described in WO 2008/154996.

(11) The self-sealing composition may also be an elastomer composition comprising at least a predominant elastomer, a styrene thermoplastic elastomer, extender oil and a hydrocarbon resin as described in WO 2009/059709.

(12) The layer 11 of fibre particles is applied to the layer 10 by one of the known flocking techniques. Among these techniques, use may be made of flocking by screening and beating, flocking by spraying under pressure, electrostatic flocking or else flocking that combines the pneumatic process and the electrostatic process.

(13) Preferably, the technique of flocking by spraying under pressure is used. It consists in mixing the particle fibres with pressurized air using an appropriate spray gun, then in projecting a mixture consisting of air and particles onto at least one portion of the layer 10 of self-sealing composition. The particles are guided by the airflow in order to be projected onto the tacky surface, on which they are implanted.

(14) Another flocking application technique used is the electrostatic technique. This technique consists in subjecting the particles to an electric field, thus creating a high potential difference, of the order of 10 kV. The charged particles are then injected onto the surface of the layer 10 of self-sealing composition.

(15) Depending on the size of the electrostatic force applied, it is possible to give the particles high accelerations, ensuring a deep embedding thereof, and consequently a good hold, and a high surface density.

(16) The treatment of the tire according to an embodiment of the invention may be used in any type of tire for a motor vehicle, such as a motor vehicle of the two-wheeled, passenger or industrial type or for a non-motorized vehicle such as a bicycle. The tire according to an embodiment of the invention may be used for passenger vehicles capable of running at very high speed, or for heavy-duty vehicles capable of running and operating under particularly high internal temperature conditions.

(17) The layer of particles is preferably positioned on the inner wall of the tire, partially or totally covering it. But this layer may be completely integrated into its internal structure.

(18) The tire according to an embodiment of the invention has the advantage of exhibiting, over a very broad range of operating temperatures, very little degradation, especially in terms of punctures.

(19) Dynamic and static puncture tests were carried out on the tire according to an embodiment of the invention. The results of these tests are collated below.

(20) Dynamic puncture with nail penetration: the puncture of less than 5% of tire is observed regarding this anti-puncture performance.

(21) Dynamic puncture with screw penetration: the puncture of around 10% of tire is observed regarding this anti-puncture performance.

(22) Static puncture at a temperature of 0 C.: the puncture of less than 2% of tire is observed regarding this anti-puncture performance.

(23) Static puncture at a temperature of 10 C.: the puncture of around 20% of tire is observed regarding this anti-puncture performance.