HEAT TREATMENT OF A REINFORCEMENT ELEMENT

Abstract

A method for manufacturing a reinforced ply comprising an elastomer composition and at least one metallic reinforcing element includes subjecting the reinforcer to a specific heat treatment.

Claims

1.-15. (canceled)

16. A method for manufacturing a reinforced ply comprising an elastomer composition and at least one metallic reinforcer comprising at least the following successive steps: (a) unwinding the reinforcer from storage means on which the reinforcer is wound; (b) heat treating the unwound reinforcer under temperature and time conditions such that T+13.7.ln(t)>175, where T is a treatment temperature in C.° and t is a time for which the reinforcer is kept at the temperature T in seconds; (c) feeding the heat-treated reinforcer into a step in which the reinforcer is embedded in an elastomer composition in order to obtain a reinforced ply.

17. The method as set forth in claim 16, wherein step (b) is carried out under temperature and time conditions such that T+28.4.ln(t)<398.

18. The method as set forth in claim 16, wherein the treatment time of step (b) is within an interval ranging from more than 0 to less than 60 s.

19. The method as set forth in claim 18, wherein the temperature is within an interval ranging from 130 to 400° C.

20. The method as set forth in claim 16, wherein the heat treatment time is within an interval ranging from more than 0 to less than 5 s and the temperature is within an interval ranging from more than 200 to 400° C.

21. The method as set forth in claim 16, wherein the treatment time of step (b) is within an interval ranging from more than 0 to less than 20 s, where T is less than or equal to 300° C. if the treatment time is less than 2 s, and T−23.8.ln(t)<315 for a treatment time ranging from 2 to less than 20 s.

22. The method as set forth in claim 16, wherein steps (a) to (c) take place continuously, step (b) being performed on a continuously travelling portion of reinforcer.

23. The method as set forth in claim 22, wherein the reinforcer travels at a speed of between 5 and 120 m/min.

24. The method as set forth in claim 16, wherein the metallic reinforcer is a single metallic filamentary element.

25. The method as set forth in claim 16, wherein the metallic reinforcer is an assembly of a plurality of metallic filamentary elements assembled together in a helix.

26. The method as set forth in claim 24, wherein a diameter of the metallic filamentary element ranges from 0.05 mm to 0.60 mm.

27. The method as set forth in claim 24, wherein a diameter of the metallic filamentary element ranges from 0.18 mm to 0.45 mm.

28. The method as set forth in claim 16, wherein the metallic reinforcer is not coated with a polymer composition prior to step (c).

29. The method as set forth in claim 16, wherein the elastomer composition used in step (c) predominantly comprises a diene elastomer selected from the group consisting of natural rubber, synthetic polyisoprene or a mixture thereof.

30. The method as set forth in claim 16, wherein a plurality of reinforcers are unwound from a plurality of storage means on which the reinforcer is wound, the plurality of reinforcers is collectively heat treated, and the plurality of reinforcers resulting from the heat treatment step is fed into a step in which the plurality of reinforcers is embedded in an elastomer composition in order to obtain a reinforced ply.

Description

DESCRIPTION OF THE FIGURES

[0059] FIG. 1 shows the measuring of the bend C of a sample of a reinforcer 33.

[0060] FIG. 2 schematically shows a method according to the invention. A plurality of reinforcers (30) is unwound from a plurality of storage means, here reels (20). The reinforcers of the plurality of reinforcers are positioned parallel to each other before being treated in a heat treatment step (40), and then feed a step (50) wherein the plurality of reinforcers is embedded in an elastomer composition in order to obtain a reinforced ply (60).

EXAMPLE

Measurements and Comparative Tests

[0061] In order to measure the bend of the reinforcer following storage and after treatment in step b) of the method according to the invention, the height of the arc formed by a sample of the reinforcer is measured as follows: [0062] a reinforcer sample (33) having a length of 60 mm is cut, [0063] the bend C of the reinforcer sample (33) is measured as illustrated in FIG. 1, the reinforcer sample (33), laid on a horizontal plane, substantially forming an arc, the arc being characterized by its height or, in other words, the maximum distance between the arc and the chord (62) that underlies it, perpendicularly to the chord.

[0064] Three bend measurements are taken: [0065] after wire drawing or assembly, just before the reinforcer is wound onto a “B80” reel with a view to storage, [0066] after storage, on a reinforcer sample taken from near the hub of the reel, that is, a sample that has undergone the greatest bending on winding, [0067] after heat treatment (where appropriate), in order to evaluate the reduction in bend prior to the step of embedding the cord in an elastomer matrix.

[0068] Two reinforcers are evaluated. The first, denoted “1.32”, is a metallic monofilament having a diameter of 0.32 mm. The second, denoted “9.35”; it is a two-layer assembly of metallic monofilaments having a diameter of 0.35 mm, a 2+7 structure and a pitch of 7.7/15.4.

[0069] These two reinforcers are commonly used for reinforcing tire plies.

[0070] The “B80” storage reels are standard reels, having a hub diameter of 118 mm.

[0071] The “ply curl” is qualitatively assessed at the output of the step of embedding in an elastomer matrix. A width of ply is cut and positioned on a flat surface, and the way in which the corners of the ply turn up is evaluated. A “−” evaluation indicates that the ply can be incorporated into a tire subject to the adjustment of the settings of the tire building machines or manual intervention, a “−−” evaluation indicates that the ply cannot be incorporated into a tire, and a “+” evaluation indicates that the ply can be incorporated into a tire without adjusting the settings of the building machines.

[0072] Table 1 collates the tests carried out.

TABLE-US-00001 TABLE 1 Bend Heat Treatment conditions Bend after Bend after Condition heat before storage T time T + 13.7 .Math. treatment Ply curl Reinforcer storage Storage (mm) (° C.) (s) ln(t) (mm) evaluation 1.32 15 6 months 140 No treatment −− 1.32 15 6 months 140 270 1 270 15 + 1.32 15 6 months 140 270 0.5 261 15 + 1.32 15 6 months 140 150 2.5 163 40 − 9.35 15 1 month 55 220 0.5 211 15 + 9.35 15 1 month 55 120 2.0 130 50 − 9.35 15 1 month 55 140 5.0 162 40 −

[0073] It will be noted that implementing the method according to the invention makes it possible to obtain reinforced plies that can be incorporated into a rubber article, here a tire, without any need to adjust the settings of the building machines. In particular, applying the heat treatment makes it possible to return to the initial bend obtained at the end of the method for manufacturing the reinforcer (wire drawing or assembly).