Tire provided with an outer sidewall containing a composition comprising a crumb rubber

Abstract

A tire is provided with an outer sidewall, said outer sidewall comprising at least a rubber composition based on at least an elastomer, a reinforcing filler, a crosslinking system and more than 25 phr of a crumb rubber.

Claims

1. A tire provided with an outer sidewall, the outer sidewall comprising at least a rubber composition based on at least an elastomer, a reinforcing filler, a crosslinking system and more than 25 phr of a crumb rubber, wherein the crumb rubber has a chloroform extract of which the weight-average molecular weight is greater than 10,000 g/mol.

2. A tire provided with an outer sidewall, the outer sidewall comprising at least a rubber composition based on at least an elastomer, a reinforcing filler, a crosslinking system and more than 25 phr of a crumb rubber, wherein the crumb rubber has not undergone any modification by a treatment selected from the group consisting of thermal, mechanical, biological and chemical treatments and combinations thereof, and wherein the crumb rubber has an acetone extract of between 3% and 15% by weight.

3. A tire provided with an outer sidewall, the outer sidewall comprising at least a rubber composition based on at least an elastomer, a reinforcing filler, a crosslinking system and more than 25 phr of a crumb rubber, wherein the crumb rubber has not undergone any modification by a treatment selected from the group consisting of thermal, mechanical, biological and chemical treatments and combinations thereof, and wherein the crumb rubber has a chloroform extract of between 3% and 20% by weight.

4. A tire provided with an outer sidewall, the outer sidewall comprising at least a rubber composition based on at least an elastomer, a reinforcing filler, a crosslinking system and more than 25 phr of a crumb rubber, wherein the crumb rubber has not undergone any modification by a treatment selected from the group consisting of thermal, mechanical, biological and chemical treatments and combinations thereof, and wherein the crumb rubber has a ratio of a chloroform extract to an acetone extract, expressed as weight percentage, of less than 1.5.

5. A tire provided with an outer sidewall, the outer sidewall comprising at least a rubber composition based on at least an elastomer, a reinforcing filler, a crosslinking system and more than 25 phr of a crumb rubber, wherein the crumb rubber has not undergone any modification by a treatment selected from the group consisting of thermal, mechanical, biological and chemical treatments and combinations thereof, and wherein the crumb rubber has a chloroform extract of which the weight-average molecular weight is less than 10,000 g/mol.

Description

III—EXEMPLARY EMBODIMENTS OF THE INVENTION

(1) III-1 Preparation of the Examples

(2) In the examples which follow, the rubber compositions were produced as described above.

(3) III-2 Characterization of the Examples

(4) Characterization of the Crumbs:

(5) In the examples, the crumb rubbers are characterized as indicated below.

(6) Measurement of the Particle Size:

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

(8) Measurement of the Acetone Extract:

(9) The acetone extract content is measured according to Standard ISO1407 by means of an extractor of soxhlet type.

(10) A sample test specimen (between 500 mg and 5 g) is introduced into an extraction chamber 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.

(11) The sample is weighed after extraction. The acetone extract content corresponds to the loss of weight of the sample during the extraction, related back to the initial weight thereof.

(12) Measurement of the Chloroform Extract:

(13) The chloroform extract content is measured according to Standard ISO1407 by means of an extractor of soxhlet type.

(14) A sample test specimen (between 500 mg and 5 g) is introduced into an extraction chamber 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.

(15) The sample is weighed after extraction. The chloroform extract content corresponds to the loss of weight of the sample during the extraction, related back to the initial weight thereof.

(16) Measurement of the Average Molecular Weights of the Chloroform Extract:

(17) The molecular weights are determined by size exclusion chromatography, according to a Moore calibration and according to Standard ISO16014.

(18) The measurement of the weight-average molecular weight (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 the company Agilent. These columns are placed in a column oven thermostated at 35° C. The mobile phase used is non-anti-oxidized tetrahydrofuran. The flow rate of the mobile phase is 1 ml/min. The RI detector is also thermostated at 35° C.

(19) The chloroform extract is dried under a nitrogen stream. The dry extract is then taken up at 1 g/l in non-anti-oxidized tetrahydrofuran at 250 ppm for 2 hours with stirring. 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.

(20) 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.

(21) Measurement of the Mooney Viscosity (or Mooney Plasticity)

(22) Use is made of an oscillating consistometer as described in French Standard NF T 43-005 (1991). The Mooney plasticity measurement is performed according to the following principle: the composition in the raw state (i.e. before curing) is moulded in a cylindrical chamber heated to 100° C. After preheating for one minute, the rotor rotates within the test specimen at 2 revolutions/minute and the working torque for maintaining this movement is measured after rotating for 4 minutes. The Mooney plasticity (ML 1+4) is expressed in “Mooney unit” (MU, with 1 MU=0.83 newton.metre). The lower the Mooney value, the lower the viscosity before curing and the better the processability of the composition.

(23) Measurement of the Carbon Black Weight Fraction:

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

(25) Characterization of the Compositions:

(26) In the examples, the rubber compositions are characterized, before and/or after curing, as indicated below.

(27) Tear Properties at 60° C. (After Curing):

(28) The dynamic properties, the elongation at break (in %) and the energy at break (in J) at 60° C. are measured by tensile tests according to French Standard NF T 46-002 of September 1988. All these tensile measurements are carried out under standard conditions of temperature (60±2° C.) and hygrometry (50±5% relative humidity), according to French Standard NF T 40-101 (December 1979).

(29) The results are expressed in terms of performance base 100, that is to say that the value 100 is arbitrarily assigned to the best control, in order to subsequently compare the values of the various solutions tested. In this way, a lower value represents a decrease in tear strength performance (that is to say a decrease in the elongation at break/energy at break), whereas a higher value represents a better performance.

(30) Cost Performance of the Composition:

(31) The cost of the composition is evaluated as a function of all its ingredients in $/kg, as a function of the percentage of each component and of its unit cost.

(32) The results are expressed in terms of performance base 100, that is to say that the value 100 is arbitrarily assigned to the best control, in order to subsequently compare the values of the various solutions tested. In this way, a lower value represents a decrease in the cost performance of the composition (that is to say an increase in the price per kilogram), while a higher value represents a better performance (that is to say a decrease in the price per kilogram).

(33) III-3 Examples

(34) The compositions are manufactured with introduction of all of the constituents into an internal mixer, with the exception of the vulcanization system. The vulcanizing agents (sulfur and accelerator) are introduced into an external mixer at low temperature (the constituent rolls of the mixer being at around 30° C.).

(35) The object of the examples presented in Tables 1 and 3 is to compare the different rubber properties of a control composition (C1, C4) to the properties of compositions that are of use to the invention (C2, C3, C5 and C6). The properties measured, before and after curing, are presented in Tables 2 and 4.

(36) TABLE-US-00001 TABLE 1 C1 C2 C3 NR (1) 50 50 50 BR (2) 50 50 50 Carbon black (3) 56 56 56 Crumb 1 (4) 0 30 50 Plasticizing oil (5) 22 22 22 Antioxidants (6) 4 4 4 Anti-ozone wax (7) 1 1 1 Stearic acid (8) 1 1 1 Zinc oxide (9) 2.4 2.4 2.4 Accelerator (10) 0.85 0.85 0.85 Sulfur 1.7 1.7 1.7 (1) NR: Natural rubber (2) BR with 0.5% of 1,2-units; 2% of trans-; 96.5% of 1,4-cis- (Tg = −107° C.) (3) Carbon black, ASTM N330 grade (4) Crumb rubber sold under the name HTR704 by the company Eswar and as described below: Crumb HTR704 Acetone extract 14.5% Chloroform extract 28.3% Mw (CHCl.sub.3 extract) 41 000 g/mol Mooney viscosity 60 (5) MES oil, Catenex SNR, from the company Shell (6) N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine (Santoflex 6-PPD) from Flexsys and 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) (7) Anti-ozone wax, Varazon 4959 from the company Sasol (8) Stearin, Pristerene 4931 from the company Uniqema (9) Zinc oxide, industrial grade - Umicore (10) N-Cyclohexyl-2-benzothiazolesulfenamide (Santocure CBS from Flexsys)

(37) TABLE-US-00002 TABLE 2 C1 C2 C3 Tearability performance at 60° C. 100 132 140 (base 100) Breaking energy (base 100) 100 140 134 Cost performance of the 100 105 110 composition (base 100)

(38) TABLE-US-00003 TABLE 3 C4 C5 C6 NR (1) 50 50 50 BR (2) 50 50 50 Carbon black (3) 56 56 56 Crumb 2 (4) — 23 54 Plasticizing oil (5) 22 25 29 Antioxidants (6) 4 4 4 Anti-ozone wax (7) 1 1.1 1.3 Stearic acid (8) 1 1.1 1.3 Zinc oxide (9) 2.4 2.7 3.2 Accelerator (10) 0.85 1.0 1.1 Sulfur 1.70 1.9 2.3 (1) NR: Natural rubber (2) BR with 0.5% of 1,2-units; 2% of trans-; 96.5% of 1,4-cis- (Tg = −107° C.) (3) Carbon black, ASTM N330 grade (4) Crumb rubber of heavy-weight vehicle tyre tread, used milled. The milling is carried out on a piece of equipment, CUM150, from the company Netzsch using spike diameters of 3 mm and a mill rotation speed of 15 000 rpm. The flow rate of matter is about 50 kg/h and the facility is cooled in order to guarantee a mill outlet gas temperature of −60° C. Crumb Acetone extract 4.5% Chloroform extract 6.3% Mw (CHCl.sub.3 extract) 7000 g/mol Particle size (D50) 155 μm (5) MES oil, Catenex SNR, from the company Shell (6) N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine (Santoflex 6-PPD) from Flexsys and 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) (7) Anti-ozone wax, Varazon 4959 from the company Sasol (8) Stearin, Pristerene 4931 from the company Uniqema (9) Zinc oxide, industrial grade—Umicore (10) N-Cyclohexyl-2-benzothiazolesulfenamide (Santocure CBS from Flexsys)

(39) TABLE-US-00004 TABLE 4 C4 C5 C6 Tearability performance at 60° C. 100 113 113 (base 100) Breaking energy (base 100) 100 122 116 Cost performance of the 100 104 108 composition (base 100)

(40) Compared to the control compositions, it is noted that the compositions in accordance with the invention make it possible to improve the tear strength performances by at least 13% while at the same time allowing a much reduced cost.