MXPA97006694A - Truck rim with nervadura / ran configuration band - Google Patents

Abstract

The invention relates to a rim with a rubber band of a lid / base type construction, with the band cap in rib / groove configuration, in contrast to a band-shaped ring / groove cover. The band cap is composed of a styrene / butadiene copolymer rubber and an isoprene / butadiene copolymer rubber and is reinforced with a mixture of carbon black, and the underlying band base is composed primarily of natural rubber of cis-1, 4-polyisoprene reinforced with carbon black. The invention relates particularly to truck tires and bus rims, which are collectively referred to herein as "truck tires".

Description

TRUCK RIM WITH NERVADURA GROUND CONFIGURATION BAND FIELD This invention relates to a rim with a rubber band of cap / base construction, wherein the band cap is of a rib / groove configuration, in contrast to a ring-shaped band / groove cover. Such a tire is intended to be used primarily on roads and not the use of off-road vehicles. It is intended that the rims of this invention are not ring / groove configuration, which is composed of a multiplicity of individual band rings that are not circumferential around the rim band by nature, and, instead, they are directed to rims with a band cap of a multiplicity of spaced, circumferential, continuous ribs, with associated slots between the ribs. The invention relates particularly to truck tires and bus rims, collectively referred to herein as "truck tires". Background Pneumatic rubber tires are conventionally prepared with a composite band of elastomer (s), reinforced with carbon black (and sometimes with silica or a combination of carbon black and silica). This invention is directed more specifically to truck tires and other relatively large tires, which include light truck tires, for relatively heavy work, which is normally expected to be capable of supporting and carrying relatively large vehicle loads and, thus, tend to generate a higher internal temperature than comparable passenger-type wheels. The bands of the truck tires of this invention are typically of a cap / base construction. The band cap for this invention has a rib / groove configuration in contact with the ground, in contrast to a ring-shaped band / groove cover, with the eternal surfaces of the raised ribs tried to make contact with the ground. The ribs of the band cap extend circumferentially and continuously around the rim. The base of the rim is subjacent and supports the band cap and is placed between the band cap and the rim shell. In general, the band cap and the band base are co-extruded together as an uncured component of the rim construction and cured or vulcanized together with the overall construction of the rim in a suitable mold, under temperature conditions and high pressures. Such constructions and methods of preparation are well known to those skilled in the art. The strip base is not normally intended to make contact with the ground and, thus, does not normally attempt to have the same measurements of the properties of the strip, as, for example, the properties of the traction and wear strip cover of the web. band. In practice, for relatively heavy duty rims, the reduced formation of cracks in the grooves of the band cover, which have a rib and groove configuration, is often desired. Usually, such crack formation of the groove, when it occurs, can be observed with a band cover groove in its base portion at the bottom of the groove, such as near its center or in its, or where its, base portion it joins the walls of the slot, which is sometimes referred to as "support". It is considered that the band of a cap / base construction will have a band base primarily reinforced with carbon black. The cap / base constructions, in general, for rim bands, are well known to those skilled in the art of these tire bands. For example, see the patent of E. U. A., No. 3,157,218.

The term "per", when used herein and in accordance with conventional practice, refers to "parts of a respective material per 100 parts by weight of rubber or elastomer". In the description of this invention, the terms "rubber" and "elastomer", when used herein, unless prescribed otherwise, are used interchangeably. The terms "rubber composition", "composite rubber" and "rubber compound", when used herein, unless otherwise prescribed, are used interchangeably to refer to "rubber that has been combined or mixed with several ingredients or materials "and such terms are well known to those skilled in the art of mixing or composition * of rubber. The glass transition temperature (Tg) of a polymer, particularly an elastomer, as used herein, unless otherwise prescribed, refers to its glass transition temperature, which can be determined conventionally, by For example, by the differential scanning calorimeter, at a heating rate of 15 s at an observed temperature * transition versus the time curve. It will be understood that such determination of Tg is well known to those skilled in the art.

Compendium? Practice of the Invention According to this invention, a pneumatic rim having a cover / base construction band and the outer surface, intended for contact with the floor of the band cover has a rib / groove configuration, composed of three to seven continuous circumferential ribs, spaced, inclusive, with two to six associated joint grooves, between the ribs, in which the rim has a maximum load limit classified by the association TRA of at least 1220 kg, alternatively at least about 2730 kg and generally in a range of 2043 to 5000 kg, at an inflation pressure in the range of 723 to 792 kPa approximately, and a flange diameter of at least 48 cm, alternatively, at least about 56 cm, and generally in the range of approximately 48 to 64 cm, with the condition that, for its cover / base band construction: (A) the band cover is comprised of, based on 100 parts by weight (per) d elastomers: (i) elastomers comprised of (a) about 10 to 40, alternatively 25 to 35, per of a styrene / butadiene copolymer, prepared by the organic solution polymerization, having a styrene content of about 15 25% and a Tg in the approximate range of -70 to -800C, (b) approximately 60 to 80, alternatively around 65 to 75 per pound of isoprene / butadiene copolymer, which has an isoprene content in the approximate range from 40 to 60 percent and a Tg in the approximate range of -60 to -90SC, (2) approximately 40 to 80, alternatively from 50 to 70, per of a carbon black reinforcement filler, as (a) about 60 to 70 weight percent of the carbon black, which has an iodine adsorption value in the approximate range of 115 to 130 g / kg and a DBP number in the approximate range of 105 to 118 cm3 / 100 g , correspondingly, (b) about 40 to 30 weight percent carbon black, which has an iodine adsorption value in the range of approximately 105 to 113 g / kg and a DBP number in the range of approximately 120 to 130 cm3 / 100 g; and (B) the elastomer of the web base is natural rubber, cis-1,4-polyisoprene, reinforced with about 20 to 60, alternatively about 25 to 40, per carbon black. In one aspect, the band cap is of a rib-groove configuration, with a multiplicity of continuous, spaced circumferential ribs with associated slots therebetween therebetween. The slots are "slots attached" in the sense that they are placed between the ribs and thus connected or joined in the configuration of the rim band. Such a band cap construction is well known to those skilled in the art and these rims are often intended for use on roads compared to vehicular use out of the way. It will be appreciated that the ribs may have a multiplicity of very small micro-grooves, through their outer surface, however, it is considered here that these ribs are still continuous in nature, since the micro-grooves are intended to be very narrow and very shallow in nature, without appreciable width or depth, usually only a few millimeters deep and do not extend through the full depth, or base, of the associated slots in the band cap. The use of micro-grooves in the band ribs, or rolling rings, is believed to be well known to those skilled in the art. The "maximum rated load limit" of the aforementioned TRA, characteristic of the rim, is intended to present a truck tire typically designed to operate under load conditions substantially greater than conventional passenger vehicle wheel loads and, so, to differentiate such a truck tire from a typical passenger tire. The term "TRA" refers to "The Tire and Rim Association Inc.", which is well known by those familiar with the manufacture of tires. * The TRA is an association that has, as a purpose "... the establishment and promulgation of the interchangeability standards for tires, rims or metal rims and related parts for the guide of the manufacturers of such products ... ". The TRA publishes an annual book, for example the annual book of 1995, which includes, for example, characterizations of truck tires and rims of passenger vehicles, which include the maximum rated load values at various inflation pressures. It can be easily seen that most truck tires, particularly for medium and large truck tires, have maximum rated load values at various inflation pressures that are substantially greater than conventional passenger vehicle tires. Therefore, it is considered here that such values effectively make a difference from the truck tires attempted for this invention of passenger vehicle tires. For purposes of the description of this invention, the diameters of the ri is mentioned in the Annual Book of TRA equal to the diameters of the rim flange. Suitably, the diameters of the flanges of the rims are considered here as being measured from the surface of the rubber-coated wire flanges and not the wire portion of these flanges, as is believed to be appropriate here. As noted above, it is considered here that truck tires, primarily tires having band configurations having at least one circumferential, substantially continuous band rib, and usually bus tires, typically have a significantly greater need for inhibition of Splitting of the slot within these grooves in the rib surface / groove of the band cover. Such a rib configuration for a truck or bus rim band cap is intended to be used primarily on roads and not primarily off-road use, which is believed to be well known to those skilled in the art. For such purposes of the rib / groove rim band of this invention, it is here considered that a cover / base construction band is convenient where the band cover is composed primarily of a styrene / butadiene copolymer rubber and a isoprene / butadiene copolymer rubber, together with the prescribed carbon blacks, and where the compositions of the band cap and the band base cooperate to promote such general effects. In practice, such a cover / base band construction is created by coextruding the band cap and the band base together, through a single die, to form the extruded band construction. Typically, the unvulcanized composite rubber compositions for the band cap and the band base are extruded through the die at a temperature, for example, in the range of about 100 ° C to 12 ° C, often typically about 110 ° C and , a ^ í, is considered to be a relatively hot extrusion process, although actual extrusion temperatures, by themselves, are considered normal for a rubber extrusion process. The strip extrudate is then formed in a rubber tire shell or frame to create a set thereof. The assembly is then vulcanized, or cured, at an elevated temperature at which the rib / groove configuration of the rim band is formed. Such a general process is well known to those skilled in the art. In this way, then, by the mentioned coextrusion process and the co-vulcanization of the band cap and the band base, the latter are considered here as a cooperative, integral unit of the rim. Therefore, it is considered here that the band cap and the band base cooperate conveniently with each other to promote the fracture resistance of the rim groove.

Thus, belt wear, together with an acceptable fractionation of the groove and relatively cold operating property of the rim, is intended to be manifested in a longer service life for the rim housing, or casing. In particular, the isoprene-no / butadiene copolymer rubber has a relatively low Tg, of the order of -60 to -802C, which is considered to be significant here and beneficial for the tire band cap to promote an improvement, or increase , in the wear property of the band. The styrene / butadiene rubber, prepared by the solution polymerization is considered here as significant and beneficial for the rim band cap, in order to promote an improvement, or increase, in the wear property of the rim and a reduction in the tear properties of the rubber composition with an increase in crack propagation resistance. The use of two different carbon blacks of the prescribed properties is considered here to be significant and beneficial for the band cap, in order to promote an improvement in the wear of the band and a reduction in the generation of heat. Examples of various carbon reinforcing blacks for use in this invention for the band cap can be found, for example, in the manual The Vanderbilt Rubber Handbook, (1978), page 417. Representative of a carbon black having an iodine adsorption value of 105 to 130 g / kg and a DBP number of 105 to 118 cm3 / 100 g is, for example, N299. Representative of a carbon black having an iodine adsorption value of 100 to 113 g / kg and a DBP number of 120 to 128 cm3 / 100 g is, for example, N234. Those skilled in the art will readily understand that the rubber composition of the web can be formulated by methods generally known in the art of rubber compositions, such as the blending of various vulcanizable constituents of sulfur, with various commonly used additive materials, such as such as, for example, curing aids, such as sulfur, activators, retarders and accelerators, process additives, such as oils, resins, which include tackifying resins, silica and plasticizers, fillers, pigments, fatty acids, zinc, waxes, antioxidants and antiozonants, peptizing agents and reinforcing materials, such as, for example, silica and carbon black. As those skilled in the art know, depending on the intended use of vulcanizable material with sulfur or vulcanized with sulfur (rubbers), the aforementioned additives are commonly selected and used in conventional amounts. Typical amounts of process aids comprise about 1 to 30 per. Such processing aids may include, for example, oils and aromatic, naphthenic and / or paraffinic process mixtures of various fatty acids, such as, for example, various zinc-based soaps. Typical amounts of antioxidants comprise approximately 1 to 5 per. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine and others, such as, for example, those described in The Vanderbilt Rubber Handbook (1978), pages 344-346. Amounts typical of antiozonant agents comprise about 1 to 5 per. Typical amounts of fatty acids, when used, which may include stearic acid, usually supplied commercially as mixtures of stearic acid and other similar fatty acids, such as palmitic acid, etc., comprise approximately 0.5 to 4 per. Typical amounts of zinc oxide comprise approximately 2 to 5 per. Typical amounts of waxes comprise approximately 1 to 5 per. Often, microcrystalline waxes are used. Typical amounts of peptizing agents comprise approximately 0.1 to 1 per. Typical peptizing agents may be, for example, pentachlorothiophenol disulfide and dibenzamidodiphenyl. The vulcanization is conducted in the presence of a sulfur vulcanizing agent. Examples of suitable sulfur vulcanizing agents include elemental sulfur (free sulfur) or sulfur donor vulcanizing agents., for example, an amine disulfide, polymeric polysulfide or sulfur olefin adducts. Preferably, the sulfur vulcanizing agent is elemental sulfur. As is known to those skilled in the art, sulfur vulcanizing agents are used in an amount ranging from about 0.5 to 4 per, with the range from 1.0 to 2.5 being preferred. Accelerators are conventionally used to control the time and / or temperature required for vulcanization and to improve the vulcanization properties. Retarding agents are also used to control the vulcanization rate. In one embodiment, a single accelerator system can be used, that is, a primary accelerator. Conventionally and preferably, a primary accelerator is used in amounts ranging from about 0.5 to 4.0 per, preferably about 0.8 to 2.5 per. In another modality, combinations of primary and / or secondary accelerators can be used, with the secondary accelerator being * used in amounts of approximately 0.05 to 3 per, for example, in order to activate and improve the properties of the vulcanized. Suitable types of accelerators that can be used in the present invention are amines, disulfides, guanidines, thiophthalimides, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. Preferably, the primary accelerator is a sulfenamide. If a secondary accelerator is used, this secondary accelerator is preferably a compound of guanidine, dithiocarbamate or thiuram. The presence of relative amounts of the sulfur vulcanizing agent and the accelerators is not considered an aspect of this invention, which is directed primarily to the use of the silica as a reinforcing filler in combination with a coupling agent in a prescribed rubber mixture. The presence of relative amounts of the above additives is not considered to be an aspect of this invention, except as noted hereinabove, of the present invention, which is directed primarily to truck tires with required size and load characteristics, which use a 'cap / base' construction band with specific combinations of elastomers in the band cap and the band base, with the elastomer of the band base being reinforced with carbon black, and the elastomers of the band cap being reinforced with a prescribed precipitated silica filler and carbon black, with the required silica being used in conjunction with a silica coupler. The rim can be constructed, shaped, molded and cured by various methods, which will be readily apparent to those skilled in the art. The invention can be better understood with reference to the following examples, in which the parts and percentages are by weight, unless indicated otherwise. EXAMPLE I A rubber composition (composite rubber) was prepared from an organic solution polymerization, obtained from a styrene / butadiene copolymer rubber and an isoprene / butadiene copolymer rubber, and is herein referred to as "Sample B". A control rubber composition composed of natural rubber (cis-1, 4-polyisoprene rubber and cis-1,4-polybutadiene rubber) was prepared and is referred to herein as the "Control Sample". The rubber compositions were prepared by mixing the ingredients in several mixing steps non-productive in sequence (without the curing agents), followed by a final stage of productive mixing (basically for the curing agents), then the resulting composition was cured. under conditions of high temperature and pressure, i.e., for about 32 minutes at about 150SC. For the non-productive mixing stages, accelerators, sulfur curing agents and part of the antioxidants were excluded, which were added in the final stage of productive mixing, the ingredients were mixed in the first non-productive stage, except that the black of coal was added in the first stage (s) of non-productive mix (s). The ingredients can be mixed in each of the non-productive mixing stages for about one to five minutes, at a temperature of about 165sec, all in an internal type Banbury mixer. The resulting rubber composition (mixture) can then be mixed, in the final stage of productive mixing, the remaining ingredients in an internal type Banbury mixer, for about one to two minutes, at a temperature of about 120 ° C. The rubber was then used to prepare a rim band, which was formed in a rim shell to obtain its rim assembly and this rim assembly was vulcanized under elevated temperature and pressure conditions to form a rim with a band that It has a rib / slot configuration band cover.

The rubber composition was comprised of the ingredients illustrated in Table 1. The values, for the most part, are simply rounded to the nearest whole number. Table 1 1) Natural rubber, cis-l, 4-poisoprene. ) cis-l, 4-polybutadiene rubber, obtained as NRO Cis BR 40, from the company Enichem 3) Isoprene / butadiene copolymer rubber, having an isoprene content of about 30 percent and a Tg of about - 83SC, obtained from The Goodyear Tire & Rubber Company. 4) Polymerization of organic solution, prepared from the styrene / butadiene copolymer rubber, having a styrene content of about 18 percent and a Tg of about -702C, obtained as S1210 from the company Shell Holland. 5) Carbon black N347. 6) Carbon black GPT (General Purpose Thermal), which has iodine and DBP values of approximately 108 and 124, respectively. 7) Carbon black N299. 8) Of the diamine of the diarylparaphenylene and dihydrothromethylquinoline type. Various properties of the cured samples were determined by conventional means and are shown in the following Table 2.

Table 2 The lower value of the Hot Bounce (100 ° C) for the experimental Sample B, compared to the Control Sample A showed a predicted higher heat generation between the complete synthetic rubber composition for the Sample B and the rubber control composition. natural / cis 1,4-polybutadiene, Sample A. The value of the hot bounce is indicative of the hysteresis of the rubber composition which, in turn, predicts a measure of the potential generation of internal heat for the rubber composition during the dynamic working conditions. This is considered beneficial here because the heat generation will tend to indicate that the life of the rim band, for rims with bands of the two rubber compositions, at least as regards the durability of heat , can be substantially equivalent. Likewise, the value of the dynamic module greater than 300 percent, for Experimental Sample B, compared to Control Sample A, is indicative of greater stiffness. Such property predicts a tire band with a rubber composition of Experimental Sample B, as having a better band wear property, as well as an improved dry handling, when mounted on a wheel of a vehicle and operated under working conditions compared to a similar rim with a band composed of the rubber composition of Control Sample A. In particular, it is considered here that the properties of the rubber composition of the experimental tire band cap, Composition B, taken together with the Tire Base Composition Y, particularly when compared to the Comparative Control Composition A, predict that a cap / base band construction of this invention will provide a rim with an improved property of web wear, while substantially having a substantially equivalent heat buildup.

With respect to the various tests, for the tests of voltage elongation and value of the module to 300%, reference is made to the test ASTM D412.92, method B. For rebound tests, reference is made to the DIN standard 53512. For hardness, Shore A, as in ASTM 2240-91, the test can be performed at room temperature, or approximately 23 seconds. For the flexometer test, reference is made to the ASTM D623 Test. The flexometer test is considered here as significant, because it specifically measures the elevation of the temperature in the rubber test sample and the changes in sample size over time. The Flexometer test is well known to experts in the evaluation of rubber compositions, particularly for use on tires. For the E 'values, which are sometimes referred to as "voltage storage module", reference may be made to Science and Technooav of Rubber, second edition 1994, Academic Press, San Diego, CA, edited by James E. Mark and collaborators, pages 249-254. The use of the storage module, E ', to characterize rubber compositions, is well known to those skilled in the art.

The tangent delta, or tan. delta, is a ratio of the voltage loss modulus, also known as E ", to the voltage storage module (E1) .These properties, that is, E1, E" and tan. delta, characterizes the viscoelastic response of a rubber test sample to a strain strain at a fixed frequency and temperature, measured at 100 ° C. The tan. delta and the tension storage module (E *) are well known to those skilled in the art of characterizing rubber compositions, particularly as it relates to tires and tire treads. The values of the stress storage module (E1) are indicative of the rigidity of the rubber compound, which may be related to the belt wear regimes and the uniform manner of belt wear. The value of tan. delta to OOOO ^ C is considered as indicative of hysteresis or heat loss. EXAMPLE II Tires of size 10.00-20, 16PR-10PA, were produced with bands of an extruded lid / base construction with the band base being the composition of the Sample Y and the band cap being of the rubber compositions. shown as Experimental Sample B and Control Sample A of Example I, as shown in Table 1 and correspondingly identified herein as Experimental Tire B and Control Tire r *. The outer cap strip, which is intended to make contact with the floor surface, is of a rib / groove configuration with five circumferentially spaced continuous ribs with four associated slots between the ribs. Each rib has a multiplicity of micro-grooves on its surface, which, for the purposes of this invention, the ribs are still considered continuous, particularly since the micro-grooves are only on the surface of the ribs and do not extend deeply inside the slots and certainly not on the bottoms of the slots. The tires were tested by the test procedures for * them and the results are shown in the following Table 3. The values for the Rim A of Control normalize to the values of 100 and the associated values for the Rim B are mentioned with the comparative values to the values for Rim A of Control.

Table 3 Table 3 shows that the rim of this invention showed a drastic reduction in the tendency to crack formation in the groove, as is evident from a lower number of damages, according to the Chevron Rib Tear test (Chevron Rib Tear ) and also free of cracks in the groove after the strip wear test. The number of damages shown in Table 3 refers to the number of cracks observed in the bottom of the band groove, adjacent to the band rib. Table 3 shows that the rim of this invention was observed to provide a drastically increased belt wear value in the approximate range of 116 to 119, an average range of values for two tests of four tires each. It is considered that this benefit, in comparison with the Control Tire A, is primarily due to the rubber composition of the tire cap used for the rim, ie the combination of the rubber cis-l, 4-polyiso-preno, rubber isoprene / butadiene copolymer and cis-1,4-polybutadiene rubber, together with the carbon black and the silica reinforcement (with its corresponding silica coupler), in combination with the rubber base of the rubber composition of 1, 4-polyisoprene. The aforementioned Chevron Rib Tear test was conducted by mounting the appropriate tire (s) on a wheel on a wheel of an appropriate vehicle and the vehicle driven in the course of the road, which has raised portions in shape. of V (in chevron configuration), on the bed of the road and the nature of the damage can be described as formation of groove fissures - tearing of the rib. A greater number of damages is considered a worse performance. fissure of the slot, within it, is the first stage of the tearing of the band rib. For example, the tearing of the rib is more often a consequence of the formation of fissures in the band groove of the groove support region in the area where the base of the groove meets the groove wall. The mentioned values of resistance are in accordance with ECE (European regulations), test No. 54 for tire resistance. Comparative values of tire strength show that Tire A runs slightly more before failure, an indication that some loss of internal heat is generated by Tire B. This result is considered very significant, because the experimental B combination of Tire rim cap / base results in significantly better wear with substantially equivalent heat generation. Improved wear is beneficial to the life of the tires in a tire wear and the generation of substantially equivalent heat is also beneficial to the tire's resistance, or life of the belt. While certain embodiments and representative details have been shown in order to illustrate the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein, without departing from the spirit and scope of the invention.

Claims (2)

1. CLAIMS 1. A pneumatic rim of a cap / base construction, is provided with an external surface, which is intended for contact with the floor of the band cap, which has a rib / groove configuration of three to seven, inclusive , spaced, circumferential, continuous ribs, with all to six adjacent grooves, correspondingly associated, between the ribs, in which the rim has a maximum load limit classified by the TRA association, from 2043 to 5000 kg, at a pressure of inflation in the range of 723 to 792 kPa and a flange diameter of 48 to 64 cm and this rim is characterized because, for its cover / base construction strip: (A) the band cap is comprised of, with base in 100 parts by weight (per) of elastomers: (1) elastomers comprised of (a) 10 to 40 per of a styrene-butadiene copolymer, prepared by the organic solution polymerization, having a styrene content of 15 at 25% and a temperature of transition to glass (Tg) in the range of -70 to -80 ° C, (b) 60 to 80 per of an isoprene / butadiene copolymer rubber having an isoprene content in the range of 40 to 60 percent and a Tg in the range of -60 to -902C, (2) from 40 to 80 per cent of a carbon black reinforcement filler as (a) 60 to 70 weight percent of the carbon black, which has a value of iodine adsorption in the range of 115 to 130 g / kg and a DBP number in the range of 105 to 118 cm3 / 100 g and, correspondingly, (b) from 40 to 20 weight percent of carbon black, having an iodine adsorption value in the range of 105 to 113 g / kg and a DBP number in the range of about 120 to 130 cm3 / 100 g; and (B) the elastomer of the belt base is the natural rubber of cis-1, 4-polyisoprene, reinforced with 20 to 60 per carbon black.
2. 2. The pneumatic tire of claim 1, wherein the band cap has from three to seven, inclusive, circumferentially spaced ribs, with two to six slots attached, correspondingly associated, between the ribs, wherein at least one of the ribs has a multiplicity of micro-grooves on the surface of the same, and the rim has a maximum load limit classified by the association TRA in the range of 2043 to 5000 kg, at an inflation pressure in the range of 723 to 792 kPa and a flange diameter in the range of 48 to 64 cm, this rim is characterized because, for its cover / base construction strip: (A) the band cover is comprised of, based on 100 parts by weight (per) of elastomers: (1) elastomers comprised of (a) 25 to 35 per of a styrene-butadiene copolymer, prepared by the organic solution polymerization, having a styrene content of 15 to 25% and a transition temperature to glass (T g) in the range of -70 to -802C, (b) 65 to 75 per of an isoprene / butadiene copolymer rubber, having an isoprene content in the range of 40 to 60 percent and a Tg in the range from -60 to -900C, (2) from 50 to 70 per of a carbon black reinforcement filler, such as (a) 60 to 70 weight percent of the carbon black, which has an iodine adsorption value in the range of 115 to 130 g / kg and a DBP number in the range of 105 to 118 cm3 / 100 g and, correspondingly, (b) 40 to 30 weight percent of carbon black, which has a value of iodine adsorption in the range of 105 to 113 g / kg and a DBP number in the range of approximately 120 to 130 cm3 / 100 g; and (B) the elastomer of the belt base is the natural rubber of cis-1, 4-polyisoprene, reinforced with 20 to 60 per carbon black.