TIRE COMPRISING A RUBBER COMPOSITION HAVING A PRO-OXIDANT AND A RUBBER CRUMB

Abstract

A tire comprises a rubber composition based on at least a rubber crumb, a diene elastomer, a pro-oxidant, a reinforcing filler and a crosslinking system, said rubber crumb representing 30% by mass or more of the composition, and exhibiting a ratio of the chloroform extract to the acetone extract of less than 2, the chloroform and acetone extracts being expressed as percentages by mass.

Claims

1.-11. (canceled)

12. A tire comprising a rubber composition based on at least a rubber crumb, a diene elastomer, a pro-oxidant, a reinforcing filler and a crosslinking system, wherein the rubber crumb represents 30% by mass or more of the rubber composition and exhibits a ratio of a chloroform extract to an acetone extract of less than 2, the chloroform and acetone extracts being expressed as percentages by mass.

13. The tire according to claim 12, wherein the rubber crumb is present at a content from 30% to 90% by mass.

14. The tire according to claim 12, wherein the rubber crumb is present at a content from 33% to 80% by mass.

15. The tire according to claim 12, wherein the rubber crumb is present at a content from 35% to 70% by mass.

16. The tire according to claim 12, wherein the rubber crumb is present at a content from 50% to 70% by mass.

17. The tire according to claim 12, wherein the rubber crumb exhibits a ratio of the chloroform extract to the acetone extract of less than or equal to 1.5.

18. The tire according to claim 12, wherein the rubber crumb has an acetone extract of between 3% and 15% by mass.

19. The tire according to claim 12, wherein the rubber crumb has an acetone extract of from 3% to 10% by mass.

20. The tire according to claim 12, wherein the rubber crumb has a chloroform extract of between 3% and 20% by mass.

21. The tire according to claim 12, wherein the rubber crumb has a chloroform extract of from 5% to 15% by mass.

22. The tire according to claim 12, wherein the rubber crumb exhibits an average particle size (D50) of between 10 and 400 μm.

23. The tire according to claim 12, wherein the rubber crumb exhibits an average particle size (D50) of between 50 and 250 μm.

24. The tire according to claim 12, wherein the rubber crumb exhibits an average particle size (D50) of between 70 and 220 μm.

25. The tire according to claim 12, wherein the diene elastomer is selected from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures thereof.

26. The tire according to claim 12, wherein the diene elastomer is selected from the group consisting of natural rubber, synthetic polyisoprenes, and mixtures thereof.

27. The tire according to claim 12, wherein the pro-oxidant is selected from the group consisting of iron salts, cobalt salts, organic disulfides, and mixtures thereof.

28. The tire according to claim 12, wherein the pro-oxidant is selected from the group consisting of hemin, iron acetylacetonate, cobalt acetylacetonate, 2,2′-dithiobisbenzanilide (DBD), tert-butylphenol disulfide (APDS), and mixtures thereof.

29. The tire according to claim 12, wherein the pro-oxidant is present at a content from 0.1 phr to 15 phr.

30. The tire according to claim 12, wherein the pro-oxidant is present at a content from 0.1 to 10 phr.

31. The tire according to claim 12, wherein the reinforcing filler is carbon black.

Description

IMPLEMENTATION EXAMPLES OF THE INVENTION

[0107] Characterization of the rubber crumbs and of the rubber compositions of the examples

[0108] In the examples, the rubber crumbs are characterized as indicated below.

[0109] Measurement of the Size of the Particles:

[0110] The size of the particles (in particular the D50) can be measured using a laser particle size analyzer of the mastersizer 3000 type from Malvern. The measurement is carried out by the liquid route, diluted in alcohol after an ultrasound pretreatment for 1 min in order to guarantee the dispersion of the particles. The measurement is carried out in accordance with standard ISO-13320-1.

[0111] Measurement of the Acetone Extract:

[0112] The acetone extract content is measured according to standard ISO1407 by means of an extractor of Soxhlet type.

[0113] A sample test specimen (between 500 mg and 5 g) is introduced into an extraction thimble and then placed in the extractor tube of the Soxhlet. A volume of acetone equal to two or three times the volume of the extractor tube is placed in the collector of the Soxhlet. The Soxhlet is subsequently assembled and then heated for 16 h.

[0114] The sample is weighed after extraction. The acetone extract content corresponds to the loss of mass of the sample during the extraction, related back to the initial mass thereof.

[0115] Measurement of the Chloroform Extract:

[0116] The chloroform extract content is measured according to standard ISO1407 by means of an extractor of Soxhlet type.

[0117] A sample test specimen (between 500 mg and 5 g) is introduced into an extraction thimble and then placed in the extractor tube of the Soxhlet. A volume of chloroform equal to two or three times the volume of the extractor tube is placed in the collector of the Soxhlet. The Soxhlet is subsequently assembled and then heated for 16 h.

[0118] The sample is weighed after extraction. The chloroform extract content corresponds to the loss of mass of the sample during the extraction, related back to the initial mass thereof.

[0119] Measurement of the Average Molecular Masses of the Chloroform Extract:

[0120] The molecular masses are determined by size exclusion chromatography, according to a Moore calibration and according to standard ISO16014.

[0121] The measurement of the weight-average molecular mass (Mw) of the chloroform extract is carried out by size exclusion chromatography (SEC) with a refractive index (RI) detector. The system is composed of an Alliance 2695 system from Waters, of a column oven from Waters and also of an RI 410 detector from Waters. The set of columns used is composed of two PL GEL MIXED D columns (300×7.5 mm 5 μm) followed by two PL GEL MIXED E columns (300×7.5 mm 3 μm) from Agilent. These columns are placed in a column oven thermostatically controlled at 35° C. The mobile phase used is non-antioxidized tetrahydrofuran. The flow rate of the mobile phase is 1 ml/min. The RI detector is also thermostatically controlled at 35° C.

[0122] The chloroform extract is dried under a nitrogen stream. The dry extract is subsequently taken up at 1 g/I in non-antioxidized tetrahydrofuran at 250 ppm with stirring for 2 hours. The solution obtained is filtered using a syringe and a single-use 0.45 μm PTFE syringe filter. 100 μl of the filtered solution are injected into the conditioned chromatographic system at 1 ml/min and 35° C.

[0123] The Mw results are provided by integration of the chromatographic peaks detected by the RI detector above a value of 2000 g/mol. The Mw is calculated from a calibration carried out using polystyrene standards.

[0124] Measurement of the Mass Fraction of Carbon Black:

[0125] The carbon black mass fraction is measured by thermogravimetric analysis (TGA) according to standard NF T-46-07, on an instrument from Mettler Toledo, model “TGA/DSC1”. Approximately 20 mg of sample are introduced into the thermal analyzer, then subjected to a thermal program from 25 to 600° C. under an inert atmosphere (pyrolyzable phase), then from 400 to 750° C. under an oxidizing atmosphere (oxidizable phase). The mass of the sample is measured continuously throughout the thermal program. The black content corresponds to the loss of mass measured during the oxidizable phase related back to the initial mass of sample.

[0126] In the examples, the rubber compositions are characterized, before and/or after curing, as indicated below.

[0127] Tensile Tests (after Curing)

[0128] These tensile tests make it possible to determine the moduli of elasticity and the properties at break and are based on standard NF ISO 37 of December 2005.

[0129] The nominal secant modulus (or apparent stress, in MPa, relative to the strain, which is unitless) is measured at 23° C. in second elongation (i.e., after an accommodation cycle at the extension rate provided for the measurement itself) at 10% elongation (denoted MA10).

[0130] The true stresses at break (in MPa) and the elongations at break (in %) may also be measured.

[0131] Rubber Compositions

[0132] The compositions are manufactured with introduction of all of the constituents into an internal mixer, with the exception of the vulcanization system, as described above. The vulcanization agents (sulfur and accelerator) are introduced onto an external mixer at low temperature (the constituent rollers of the mixer being at approximately 30° C.). The crumbs can be introduced into the internal or external mixer.

[0133] The object of the examples presented in tables 1 to 6 is to compare the different rubber properties of the compositions not in accordance with the invention (T1 to T4) to the properties of the compositions in accordance with the invention (C1 to C20). The amounts of the ingredients of the compositions are indicated in phr, and for the crumb a row has been added to indicate the amount in % by mass as mentioned in tables 1 to 6.

[0134] The MA10 moduli measured for all the compositions are indicated in the last row of tables 1 to 6, and it can be observed that the stiffness of the compositions in accordance with the invention is always improved compared to the compositions that are not in accordance with the invention.

TABLE-US-00001 TABLE 1 T1 C1 T2 C2 T3 C3 T4 C4 NR (1) 100 100 100 100 100 100 100 100 Crumb (2) in phr 88 88 140 140 200 200 320 320 Crumb in % 35.3 34.6 46.5 45.7 55.4 54.6 66.5 65.8 Carbon black (3) 54 54 54 54 54 54 54 54 Peptizer 1 (4) 0 5 0 5 0 5 0 5 Stearic acid (5) 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Zinc oxide (6) 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 Accelerator (7) 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 MA10 4.56 6.21 4.13 6.10 4.10 5.85 4.34 5.21 Table 1 references: (1) NR: Natural rubber (2) “OG80” crumb from CL PELLING having a content of acetone extract of 7.2 mol %, a content of chloroform extract of 7.9 mol % and a D50 of 180 μm (3) Carbon black, ASTM N234 grade (4) Hemin from bovine, purity ≥90%, from Aldrich (5) “Pristerene 4931” stearin from Uniqema (6) Zinc oxide, industrial grade - Umicore (7) N-Cyclohexyl-2-benzothiazolesulfenamide (“Santocure CBS” from Flexsys).

TABLE-US-00002 TABLE 2 T3 C3 C5 C6 C7 C8 NR (1) 100 100 100 100 100 100 Crumb (2) in phr 200 200 200 200 200 200 Crumb in % 55.4 54.6 55.3 55.3 55.1 53.9 Carbon black (3) 54 54 54 54 54 54 Peptizer 1 (4) 0 5 0.15 0.5 2 10 Stearic acid (5) 2.5 2.5 2.5 2.5 2.5 2.5 Zinc oxide (6) 2.7 2.7 2.7 2.7 2.7 2.7 Accelerator (7) 0.6 0.6 0.6 0.6 0.6 0.6 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 MA10 4.10 5.85 4.91 5.10 5.48 6.85

TABLE-US-00003 TABLE 3 T1 C1 C9 C10 C11 NR (1) 100 100 100 100 100 Crumb (2) in phr 88 88 88 88 88 Crumb in % 35.3 34.6 35.3 35.2 35.0 Carbon black (3) 54 54 54 54 54 Peptizer 1 (4) 0 5 0.15 0.5 2 Stearic acid (5) 2.5 2.5 2.5 2.5 2.5 Zinc oxide (6) 2.7 2.7 2.7 2.7 2.7 Accelerator (7) 0.6 0.6 0.6 0.6 0.6 Sulfur 1.5 1.5 1.5 1.5 1.5 MA10 4.56 6.21 5.21 5.32 5.87

TABLE-US-00004 TABLE 4 T1 C12 C13 C14 NR (1) 100 100 100 100 Crumb (2) in phr 88 88 88 88 Crumb in % 35.3 35.3 35.2 34.6 Carbon black (3) 54 54 54 54 Peptizer 2 (8) 0 0.15 0.5 5 Stearic acid (5) 2.5 2.5 2.5 2.5 Zinc oxide (6) 2.7 2.7 2.7 2.7 Accelerator (7) 0.6 0.6 0.6 0.6 Sulfur 1.5 1.5 1.5 1.5 MA10 4.56 5.29 5.14 5.41 Table 4 references: (8) 2,2′-dibenzamidodiphenyldisulfide (DBD): ″Renacit10″ from Lanxess.

TABLE-US-00005 TABLE 5 T3 C3 C15 C16 C17 C18 NR (1) 100 100 100 100 100 100 Crumb (2) in phr 200 200 200 200 200 200 Crumb in % 55.4 54.6 54.6 54.6 54.6 54.6 Carbon black (3) 54 54 54 54 54 54 Peptizer 1 (4) 0 5 0 0 0 0 Peptizer 2 (8) 0 0 5 0 0 0 Peptizer 3 (9) 0 0 0 5 0 0 Peptizer 4 (10) 0 0 0 0 5 0 Peptizer 5 (11) 0 0 0 0 0 5 Stearic acid (5) 2.5 2.5 2.5 2.5 2.5 2.5 Zinc oxide (6) 2.7 2.7 2.7 2.7 2.7 2.7 Accelerator (7) 0.6 0.6 0.6 0.6 0.6 0.6 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 MA10 4.10 5.85 4.95 5.85 4.72 5.11 Table 5 references: (9) para-tert-butylphenoldisulfide (APDS): “Vultac TB7” from Arkema (10) iron (III) acetylacetonate sold by Aldrich (11) cobalt (II) acetylacetonate hydrate sold by Aldrich.

TABLE-US-00006 TABLE 6 T3 C3 C19 C20 NR (1) 100 100 0 0 IR (12) 0 0 100 0 SBR (13) 0 0 0 100 Crumb (2) in phr 200 200 200 200 Crumb in % 55.4 54.6 54.6 54.6 Carbon black (3) 54 54 54 54 Peptizer 1 (4) 0 5 5 5 Stearic acid (5) 2.5 2.5 2.5 2.5 Zinc oxide (6) 2.7 2.7 2.7 2.7 Accelerator (7) 0.6 0.6 0.6 0.6 Sulfur 1.5 1.5 1.5 1.5 MA10 4.10 5.85 5.92 5.89 Table 6 references: (12) IR: ″SKI-3″ from Nizhnekamsk (13) SBR styrene content of 15%, content of 1.2: 25% of the butadiene part, Tg of −65° C.