MXPA99000687A - Composition and rim with rolling surface containing carbonate of lime - Google Patents

Abstract

The invention relates to a rubber composition containing relatively low levels of a carbon black and / or silica reinforcer, together with a particulate calcium carbonate and modifiers selected. The invention relates particularly to a rim having a component, particularly with a rolling surface of this composition.

Description

^ COMPOSITION AND RIM WITH ROLLING SURFACE CONTAINING CALCIUM CARBONATE " COUNTRYSIDE The invention relates to a rubber composition containing relatively low levels of carbon black and / or silica reinforcement, together with a particulate calcium carbonate and a selected modifier (s). The invention relates particularly to a rim with a component thereof, particularly a rim rolling surface.

BACKGROUND Rubber compositions are typically used for rim running surfaces that can be brought to the optimum, for various rubber composition properties in order to discuss one or more of three of the properties of the rim; namely, attraction, rolling resistance and tread. In this regard, the physical properties typically desirable for tire tread surface rubber compositions may include, for example, hysteresis, hardness and modulus. Some properties usually indicate by their properties of bounce, tangential delta (delta Tan.) To 0 ° C, and resistance to abrasion. Hysteresis is conventionally related to Hot Rebound Values. These physical properties are well known to those skilled in the rubber mixing art and, in general, are considered to be somewhat predictive of the operation of the tread surface of the rim. More specifically, it is sometimes desirable for a tire to have a relatively low rolling resistance to improve fuel economy of the vehicle. A lower hysteresis, usually evidenced by a higher hot bounce value of a cured or vulcanized rubber composition, is predictive of reduced heat buildup for the rubber composition and, hence, of its usefulness for a composition of relatively low rolling rubber for use on a tire tread surface. Frequently, an accepted practice is to reduce the particle reinforcement of a rubber composition to a relatively low level in order to reduce its hysteresis and therefore, a predictive reduction in rolling resistance for a tire tread surface application. . For example, when it could be - It is desirable to reduce a surface to the tread of the rim by reducing hysteresis, by increasing the hot rebound values of a rubber composition for a tire tread surface application, the particulate reinforcement such as carbon black and / or silica could conventionally reduced from a somewhat normal scale of about 55 to about phr, to a reduced amount of this reinforcement within the range of about 30 to about 50, and particularly about 30 to about 45 phr. This reduction in particle reinforcement for a tire tread surface rubber for reduction in rolling resistance of the rim is well known to those skilled in the art. However, in a manner compatible with the rolling resistance of the reduction of the tread surface composition of the rim by reducing the content of the filler or reinforcing filler, with the other aspects of the composition of rubbers, remaining essentially unchanged. , the wear resistance of the tread surface of the rim often decreases, as evidenced by an increase in the tread of the rim, and usually there is a degree of loss in traction of the tread surface of the rim. In one aspect, an increase in the tire tread can sometimes predict or correlate to a certain degree, the reduction in abrasion resistance of the cured rubber composition. Accordingly, it is desirable herein to provide a tire tread rubber composition with reduced hysteresis (increased hot bounce values)., while essentially maintaining acceptable abrasion resistance, and usually acceptable wheel surface tread traction. It is desirable to provide this rubber composition with low levels of carbon black and / or silica reinforcement. It is recognized herein that calcium carbonate has sometimes been used as a relatively low cost filler or filler and an expander for various polyolefin resins and some elastomers. However, it is believed herein that it has not been used on tire treads with a relatively low carbon black content together with a specified modifier (s). In the description of this invention, the term "" phr "when used herein and in accordance with conventional practice, refers to" parts of a respective material per 100 parts by weight of the rubber or elastomer. "In the description of this invention, the terms "rubber" and "elastomer" if used herein, can be used interchangeably, unless otherwise stated .The terms "rubber composition", "mixed rubber" and "rubber compound" "rubber", if used herein, are used interchangeably to refer to "rubber that has been blended or combined with various ingredients and materials" and these terms are well known to those skilled in the art of rubber mixing or stirring. of rubber.

COMPOSITION AND DESCRIPTION OF THE INVENTION According to this invention, there is provided a rubber composition, and particularly a rim with a component of this composition, including a rim rolling surface, comprising (A) 100 parts by weight of an elastomer consisting essentially of (1) ) at least one diene-based elastomer, or (2) a combination of a diene-based elastomer and an epoxidized diene-based elastomer, preferably such as a natural cis-1-polyisoprene, natural rubber ( B) from about 15 to about 45, alternatively from about 25 to about 40, phr of a particulate reinforcement that is selected from carbon black and / or precipitated silica, the silica having silanol groups on the surface thereof, ( C) about 5 to about 50, alternatively about 10 to 30, phr of particulate calcium carbonate and (D) at least one modifier comprising at least dithiodipropionic acid, nicotin amide and bis-3 (trialkoxysilylalkyl) polysulfide having an average of 2.1 to about 4 sulfur atoms in its bridge or polysulfide connection, and wherein these alkyl groups contain from two to four carbon atoms. In an aspect of the invention, wherein the elastomers are from about (a) 5 phr to about 30 phr of the epoxidized diene-based rubber, preferably epoxidized natural cis-1,4-polyisoprene rubber, containing about 20 one hundred to about 50 percent epoxidation and (b) from about 95 to about 70 phr of the diene-based rubber. In one aspect, the particulate reinforcement for the rubber composition may be composed of about 15 to about 30 phr of this carbon black without precipitated silica, or about 13 to about 35 phr of precipitated silica and about 2 to about 20 phr. carbon black phr. For the purposes of this invention, a significant aspect is the relatively low concentration of the black carbon black reinforcement in combination with the use of calcium carbonate and a modifier (s). The modifier can be dithiodipropionic acid. The modifier can be nicotinamide. The modifier can be a bis-3 (trialkoxysilylalkyl) polysulfide having from 2 to about 8, with an average of about 2.1 to about 4, sulfur atoms in its bridge or polysulfide linkage. Usually from 2.1 to about 2.5 from about 3.2 to about 4 sulfur atoms are preferred for the polysulphide bridge or connection. Usually, the trialkoxy groups are selected from trimethoxy and triethoxy groups and the remaining alkyl groups are selected from ethyl, propyl and butyl groups. In this way, this modifier, for example, could be selected from bis-1 (trimethoxysilylpropyl) polysulfide and bis-3 (triethoxysilylpropyl) polysulfide. While it is recognized that these modifiers could also sometimes be known as silica couplers having a reactive residue with the silanol groups contained on the silica surface and other residue, usually an interactive polysulfide with one or more of the base elastomers of diene, in this case, it seems that they serve to interact with calcium carbonates. Usually the modifier is present as a weight ratio of the modifier to the calcium carbonate within the range of about 1/100 to about 1/1, alternatively, within the range of about 1/50 to about 1/5 or in a more limited scale from about 1/20 to about 1/10. Other forms of silica, including fuming silica which is different from the precipitated silica, are not preferred. Usually the calcium carbonate has an average particle size diameter within the range of about 50 to about 14,000 nanometers (nm). In practice, the particulate calcium carbonate surface can not be coated, if desired, to aid its dispersion in a rubber composition. This coating, for example, may be in the form of a polyolefin material, particularly a saturated polyolefin material.

ADDITIONAL DETAILED DESCRIPTION It is considered that this invention is particularly applicable when it is desired to minimize the rolling resistance of the tread surface of the rim and, namely, to provide higher hot bounce values for a tread surface elastomer composition. of rim, but where it is also desirable to retain essentially the physical properties of the rubber composition, such as, for example, DIN abrasion that can be related to the tread, rigidity, tensile strength and modulus and / or tensile strength of the tire. the rolling surface. In the practice of this invention, it is believed that it is a considerable separation from past practice for the rubber rim running surfaces to use relatively low levels of reinforcing pigments such as carbon black and / or silica and to use correspondingly calcium as a relatively non-reinforcing filler or filler, together with a modifier (s) to increase the level of filler or total filler to a scale of about 30 to about 65 phr for the total amount of carbon black and / or silica, as the case may be, and the calcium carbonate with the amount of optional silica carbon black being restricted to a maximum of about 45 phr. The carbon blacks used can be conventional carbon reinforcing carbon blacks. These carbon blacks for example can have an adsorption value of DBP (dibultilphthalate) within the range of about 70 to about 150, usually from about 80 to about 130 cubic centimeters per 100 grams, and a corresponding Iodine adsorption value within of the scale from about 40 to about 140, usually from about 60 to about 125 grams per kilogram. Representatives of several carbon blacks, for example, which fall within the aforementioned scales, include, for example N121, "N220, N234. The reported carbon blacks N121 and N220 have a DBP value of approximately 130. and 114, respectively, and an iodine adsorption value of about 120 and 121, respectively, If desired, a combination of high-strength carbon blacks and relatively low reinforcement such as, for example, a combination of carbon black and high reinforcement NI10 and / or N220 with a relatively low carbon black reinforcement N550 and / or N660, wherein from about 60 percent to about 80 weight percent of the carbon black is the high reinforcing carbon black. An important aspect of this invention is that the addition of the calcium carbonate filler or filler and the associated modifier (s) could be used in the presence of? in the absence of silica. or possibly only a relatively small amount of silica such as for example from about 10 to about 15 or 20 phr of silica to achieve a reduction of the rebound values for a rubber composition intended for use on a rim rolling surface (prediction of lower rolling resistance), while still maintaining a satisfactory DI abrasion value for the cured rubber composition, compared to the use of relatively low levels of carbon black only for rubber reinforcement. Even though it has been proposed that the addition of considerable and therefore quantitative amounts of the precipitated silica, together with a silica coupling material compared to the use of the carbon black reinforcement to the rubber composition can improve or promote an increase in rebound values and therefore, hysteresis that is predictive of a reduction in rolling resistance for a tire tread surface, the importance of this invention is that, for many of the proposed rubber compositions to be used as a rim rolling surface, the quantitative use of the silica reinforcement may not be necessary when the rolling resistance of the relatively low tread surface is an important consideration for the tread surface of the rim. This is achieved by replacing at least a portion of the silica with calcium carbonate, but also requiring that one or more of said modifiers be present. In this way, a reduced amount of silica content could be used in the tread surface rubber composition and still achieve rebound of the rubber composition and DIN abrasion values. An importance of this discovery, at least in one sense, is even greater when it is taken into consideration that (and) silica is considerably more expensive than carbon black and calcium carbonate and, in addition, that (i) considerably more mixing time, and therefore more processing of the rubber, and usually when relatively high concentrations of silica reinforcement are used for the tread surface rubber composition.

Therefore, it is proposed for this invention that the use of calcium carbonate, together with the modifier (s), can improve the processing of the rubber composition namely by reducing the mixing time in comparison with a rubber composition containing the use of silica concentration of 60 phr or greater. It will be understood that DBP (dibutylphthalate) adsorption values can be determined by test D2414 of the American Society for Material Testing and Iodine values can be determined by test D1510 of the American Society for the Testing of Materials. For example, the value of Iodine, or number, for carbon black is a measure of its surface area and is expressed in units of gram per kilogram. A higher iodine value is indicative of a smaller particle size which in turn is indicative of a higher surface area for carbon black and typically a higher carbon black reinforcement for elastomers. The adsorption value of DBP (dibutlflate) for carbon black is a measure of its structure, or aggregate size and its higher DBP adsorption value is indicative of larger aggregates which, in turn, is indicative of a higher structure for carbon black. The values of Iodine and the DBP values together with the N numbers designated by the American Society for the Testing of Representative Materials can be found, for example, in The Vanderbilt Rubber Handbook, Thirteenth Edition (1990), page 417. In the practice of this invention, as noted above, the rubber composition consists of (y) at least one elastomer based on diene or rubber or (ii) a combination of at least one diene-based elastomer with an epoxidized diene-based elastomer such as epoxidized natural rubber. These diene-based elastomers are typically selected from homopolymers and copolymers of conjugated dienes and copolymers of a conjugated diene (s), and an aromatic vinyl compound, such as, for example, styrene and alpha-methylstyrene. These dienes, for example, can be selected from isoprene and 1,3-butadiene and these aromatic vinyl compounds can be selected from styrene and alpha-methylstyrene. This elastomer, or rubber, can be selected, for example, from at least one cis-1,4-polyisoprene rubber (natural and / or synthetic, and preferably natural rubber), 3-4-polyisoprene rubber, rubbers. of styrene / butadiene copolymer, rubbers of - - isoprene / butadiene copolymer, styrene / isoprene copolymer rubbers, styrene / isoprene / butaderene terpolymer rubbers, cis-1,4 polybutadiene rubber, trans-1, 4-polybutadiene rubber (70-95 percent trans) , low vinyl polybutadiene rubber (10 to 30 percent vinyl), high vinyl polybutadiene rubber (30 to 90 percent vinyl). In one aspect, the rubber frequently comprises at least two diene-based elastomers wherein one of the elastomers is cis 1,4-polybutadiene. This combination of elastomers can also be used in conjunction with an epoxidized diene based elastomer, such as epoxidized natural rubber. For example, this combination of two or more diene-based rubbers can be a cis-1,4-polyisoprene rubber (natural or synthetic, even when natural rubber is preferred), 3,4-polyisoprene rubber, copolymer rubber of isoprene / butadiene, styrene / isoprene / butadiene rubber, emulsion polymerization and solution derived from styrene / butadiene rubbers, cis-1, 4-polybutadiene rubbers, medium vinyl content polybutadiene rubbers (from 30 to 55 percent vinyl), high vinyl polybutadiene rubbers (55 to 90 percent vinyl) and butadiene / acrylonitrile copolymers prepared by emulsion polymerization. Epoxidized natural rubber is known to those skilled in the art and can be described as a modified form of cis-1 rubber., Natural 4-polyisoprene wherein a certain amount of its unsaturation is replaced by epoxidized groups. The epoxidized natural rubber that can be used in this invention can have an expodidated modification level ranging from about 15 percent to about 85 percent, preferably from about 20 percent to about 50 percent molar. A particularly preferred epoxidized level for natural rubber is about 25 mole percent. As is known to those skilled in the art, epoxidized natural rubber can be obtained by epoxidizing natural rubber latex. This epoxidized natural rubber can be obtained from Malaysian rubber producers under the designation, for example, of ENR 25 (25 percent epoxidized level) and ENR 50 (50 percent epoxidized level). In one aspect of this invention, styrene / butadiene (E-SBR) emulsion polymerization derivatives could be used as a diene-based elastomer having a relatively conventional styrene content of about 20 percent to about 28 percent bound to the styrene, and for some applications, an E-SBR having a relatively high bound styrene content, namely, a bound styrene content of from about 30 percent to about 45 percent. The relatively high styrene content of about 30 to about 45 for E-SBR can be considered beneficial for an object of improving traction, or resistance to skidding of the tread surface of the rim. The presence of E-SBR itself is considered beneficial for an object of improving the processability of the uncured elastomer composition mixture, especially in comparison to a use of an SBR prepared by solution polymerization (S-SBR). By E-SBR prepared by emulsion polymerization is meant that it is copolymerized in styrene and 1,3-butadiene as an aqueous emulsion. This is well known to those skilled in the art. The bound styrene content can vary, for example, from about 5 percent to about 50 percent. In one aspect, the E-SBR may also contain acrylonitrile to form a terpolymer rubber in amounts, for example, from about 2 percent to about 30 percent by weight of bound acrylonitrile in the terpolymer. The SBR prepared by solution polymerization (S-SBR) typically has a bound styrene content within the range of about 5 percent to about 50 percent, preferably from about 9 percent to 36 percent. The S-SBR can also conveniently be prepared, for example, by catalysing organolithium in the presence of an organic hydrocarbon solvent. The object of using the S-SBR is for improved rolling resistance of the rim as a result of the lower hysteresis when used in a tire tread composition. The 3,4-polyisoprene (3,4-PI) rubber is considered beneficial for the purpose of improving tire traction when used in a tire tread composition. The 3,4-PI and the use thereof is more fully described in U.S. Patent No. 5,087,668. The Tg refers to the glass transition temperature which can be conveniently determined by a differential scanning calorimeter at a heating rate of 10 ° C per minute.

The rubber of cis-1,4-polybutadiene (BR) is considered to be beneficial for the purpose of improving wear on the running surface of the rim or tread. This BR can be prepared, for example, by polymerization by organic solution of 1,3-butadiene. The BR can be conveniently characterized, for example, having at least 90 percent cis-1, 4 content. The cis-1,4-polyisoprene rubber and the natural cis-1,4-polyisoprene rubber are well known by those experts in the rubber technique. A styrene / isoprene / butadiene terpolymer elastomer (SIBR) may be used in the rubber composition of this invention. Representative examples of the various SIBRs can be found, for example, in U.S. Patent Nos. 5,137,998, 5,159,020 and 5,272,220. It will be readily understood by those skilled in the art that the rubber composition would be revolved by methods generally known in the rubber busting industry, such as the mixing of several sulfur-vulcanizable constituent rubbers with various commonly used additive materials such as for example Curing aids, eg sulfur, activators, retarders and accelerators, processing additives, such as oils, resins including tackifying resins, a coupling agent and plasticizers, fillers or fillers, pigments, fatty acid, zinc, waxes, antioxidants and antiozonants, peptizing agents and reinforcing materials, such as, for example, carbon black. As is known to those skilled in the art, depending on the use to which the vulcanizable material with sulfur and vulcanized with sulfur (rubbers) is intended, the aforementioned additives are commonly selected and used in conventional amounts. The composition of the present invention may contain conventional amounts of known rubber chemicals. Typical amounts of tackifying resins, if used, may comprise from about 0.5 to about 10 phr, usually from about 1 to about 5 phr. Typical amounts of processing aids comprise from about 1 to about 50 phr. These processing aids may include, for example, aromatic, naphthenic and / or paraffinic processing oils. Typical amounts of antioxidants comprise from about 1 to about 5 phr.

Representative antioxidants, for example, may be diphenyl-p-phenylenediamine and others, such as, for example, those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344 to 346. Typical amounts of antiozonants consist of approximately 1 to about 5 phr. Typical amounts of fatty acids, if used, which usually comprise mainly stearic acid, consists of about 0.5 to about 3 phr. Typical amounts of zinc oxide comprise from about 2 to about 5 phr. Typical amounts of waxes comprise from about 1 to about 5 phr. Frequently microcrystalline waxes are used. Typical amounts of peptizers comprise from about 0.1 to about 1 phr. Typical peptizers, for example, may be pentachlorothiophenol disulfide and dibenzamidodiphenyl. The vulcanization of the rubber composition is carried out in the presence of a sulfur vulcanization agent. Examples of suitable sulfur vulcanization 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 vulcanization agent is elemental sulfur. As it is good - - known to those skilled in the art, sulfur vulcanization agents are used in an amount ranging from about 0.5 to about 4 phr., or even under some circumstances, up to about 8 phr, with scale from about 1.5 to about 2.5, sometimes from about 2 to about 2.5, being the preferred scale. If accelerators are used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanized material. In one embodiment, a single accelerator system, ie, a primary accelerator, can be used. Conventionally, and preferably, a primary accelerator (s) is used in total amounts ranging from about 0.5 to about 4, preferably from about 0.8 to about 2 phr. In another embodiment, combinations of a primary accelerator and a secondary accelerator are used with the secondary accelerator being used in amounts of about 0.05 to about 5 phr in order to activate or improve the properties of the vulcanized material. The combinations of these accelerators could be expected to produce a synergistic effect on the final properties that are somewhat better than those produced by the use of any single accelerator. In addition, delayed action accelerators which are not affected by normal processing temperatures can be used but produce a satisfactory cure at regular vulcanization temperatures. Vulcanization retarders could also be used. The types of suitable accelerators which may be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiuramyl, sulfenamides, dithiocarbamates and xanthates. Preferably, the primary accelerator is a sulfenamide. If a second accelerator is used, the secondary accelerator is preferably a guanidine, dithiocarbamate or a thiouramyl compound. The presence and relative amounts of most of the aforementioned additives are not considered as being an aspect of the present invention that is primarily directed to the use of relatively low levels of reinforcing pigments such as carbon black and / or silica, together with a filler or filling material of calcium carbonate in the rubber compositions for running surfaces of the rim. The rubber composition can be prepared for example by working and thermomechanically mixing the diene-based rubber, epoxidized natural rubber if used, calcium carbonate, a modifier (s), carbon black and / or silica and other stirring ingredients. of rubber, excluding rubber curing agents, in at least one step of mixing in sequence with at least one mechanical mixer which is usually referred to as a "non-productive" mixing step (s), up to a temperature within the range of about 160 ° C to about 190 ° C over a sufficient length of time, usually within about 4 to about 8 minutes, is guided by a final mixing step in which the curing agents such as sulfur and the accelerators are added and mixed therewith for about 1 to about 4 minutes up to a temperature within a range of about 90 ° C to about 125 ° C. The terms of "non-productive" and "productive" mixing stages are well known to those skilled in the rubber mixing field. It will be appreciated that the rubber composition is conventionally cooled to a temperature of less than about 40 ° C between the aforementioned mixing steps. It will further be appreciated that the aforementioned duration of time for maintaining the temperature required for the mixing process (s) during the non-productive mixing steps, can be achieved for example by (y) adjusting the speed of the mixer motor, namely, reducing the speed of the engine after the desired temperature of the rubber composition is reached, in a variable speed mixer or (ii) using two or more mixing steps sufficient to satisfy the duration requirement for the maintenance of the maximum mixing temperature already mentioned. The vulcanization of the rubber composition of the present invention is generally carried out at conventional temperatures ranging from 100 ° C to 200 ° C. Preferably, vulcanization is carried out at temperatures ranging from 110 ° C to 180 ° C. Any of the usual vulcanization processes can be used, such as heating in a press or mold, heating with superheated steam or hot air or in a salt bath. During the vulcanization of the composition vulcanized with sulfur, the rubber composition of this invention can be used for various objects. For example, the rubber composition vulcanized with sulfur can be in the form of a running surface for a pneumatic tire which is the subject matter of this invention. These rims can be made, shaped, molded and cured by various methods that are known and will be readily apparent to those skilled in the art. As can be seen, the rim can be a rim for a passenger car, an airplane tire, a truck tire and the like. Preferably, the rim is a rim for a passenger car. The rim can also be a radial rim or bias, with a radial rim being preferred. The invention can be better understood by reference to the following examples wherein the parts and percentages are by weight unless otherwise indicated.

EXAMPLE I The rubber compounds containing synthetic cis-1,4-polyisoprene rubber and reinforced in various ways with carbon black, silica and calcium carbonate were prepared in a three stage Banbury mixer, (Table 1) and are referred to herein as Exp. B, C and D. A control rubber composition was prepared as Ctrl A. The cure behavior and cured properties for these compounds are shown in Table 2. The gradual replenishment of silica with 5, 10 and 15 phr of calcium carbonate (Exps. B, C and D) illustrates a significant increase in rebound values and a reduction in the Tan delta at 60 ° C compared to the control (CtrlA) without significantly affecting the healing behavior or other cured properties. The increase in the rebound value and the delta reduction Tan. (60 ° C) is predictive of improved (reduced) rolling resistance when used as a tire tread rubber composition.

Table 1 Ctrl A Exp B Exp C Exp D First Not Productive NATSYN (R) 2200"100 100 100 100 Carbon Black 35 35 35 35 Antioxidant " Processing Oil ' Zinc oxide Fatty Acid "- Second No Productive Silica 15 10 Coupling Agent Si69 (50%) 7 Calcium Carbonate 10 15 Productive Accelerator of Sul Enamida 1.0 1.0 1.0 1.0 Sulfur 1.4 1.4 1.4 1.4 1. synthetic cis-1, 4-polyisoprene from The Goodyear Tire & Rubber Company. 2. Black carbon reinforcing tread surface for general purpose (GPT). 3. Of the polymerized 1, 2-dihydro-2, 2, 4-trimethylquinoline type. 4. Naphthenic / paraffinic. 5. Mainly stearic acid which also contains palmitic and oleic acid. 6. Hi-Sil 210 from PPG Industries, Inc. 7. X50S from Degussa, A.G. as a 50/50 ratio of bis- (3-ethoxysilylpropyl) tetrasulfide and carbon black. 8. Natural ground calcium carbonate obtained as Atomite from ECC America.

Table 2 Properties Ctrl A Exp B Exp C Exp D Torque Torque Max. (Mpa) 32 31.3 31.6 32 Torque Torque Min. (Mpa) 7.4 5.5 5.2 5.5 T90, min 19.5 18.0 16.5 16.0 T25, min 13.3 12.0 11.5 11.0 Resistance to tension, Mpa 20.2 19.5 19.6 19.1 Elongation at break,% 613 593 589 573 - M100, Mpa 1.59 1.59 1.57 1.54 M300, Mpa 7.76 7.73 7.61 7.33 Rebound, TA 18.9 51.3 54.0 57.3 Bouncing, hot 61.5 63.7 66.6 69.3 Hardness, TA1 53.1 53.3 52.7 52.4 Hardness, hot 52.2 52.0 51.2 51.3 E 'at 60 ° C, MPa 10.7 9.4 .5 8.0 Delta Tan. At 60 ° C 0.089 0.089 0.080 0.064 Abrasion of DIN 144 165 180 167 (loss ce) 1. Ambient Temperature, or approximately 23 ° C. 2. 100 ° C.

EXAMPLE II The rubber compounds containing styrene / butadiene copolymer rubber prepared by emulsion polymerization (E-SBR), cis-1, 4-polybutadiene rubber and synthetic cis-1,4-polyisoprene rubber reinforced with black Coal and calcium carbonate were prepared in a three-stage Banbury mixer (Table 3) and identified herein as Exs FK. The curing behavior and the cured properties for these compounds are shown in Table 4. Compounds F, G and H contain 40 phr of carbon black and 40 phr of calcium carbonate, while compounds Y, J and K contain 30 phr of carbon black and 50 phr of calcium carbonate. Compounds G and J also contain 3 phr and 4 phr of a coupling agent of Si69 (50 percent), respectively, and compounds H and K also contain 2 phr and 2.5 phr of dithiodipropionic acids, respectively. The cured properties of calcium carbonate containing compounds are noted to have been improved by the addition of either Si69 or dithiodipropionic acid. The improvement is shown in tensile strength, 100 percent modulus, hot bounce, hardness and abrasion of DIN (the lower the better). The mixing procedure was similar to Example I.

The recipe is illustrated in the following Table 3. The resulting physical properties after curing of the rubber composition at about 36 minutes at a temperature of about 150 ° C are shown in Table 4.

Table 3 Ej F Fj G Ej H Ej I Ej J Ej K First Not Productive E-SBR1 68.75 68.75 68.75 68.75 68.75 68.75 BUDENE (R) 1207 '15.0 15.0 15.0 15.0 15.0 15.0 NATSY (R) 2200 35.0 35.0 35.0 35.0 35.0 35.0 Negro de Carbó, n3 40.0 40.0 40.0 30.0 30.0 30.0 Calcium Carbonate 20.0 20.0 20.0 30.0 30.0 30.0 Antioxidant Zinc Oxide Fatty acid Second No Productives Calcium Carbonate4 20.0 20.0 20.0 20.0 20.0 20.0 Coupling Agent of Si69 (50%; Dithio-dipropionic acid 2.5 Productive Sulfenamide Accelerator Diphenylguanidine SBR sulfur prepared by emulsion polymerization of The Goodyear Tire & Rubber Company as PLF 1712; which has a styrene content of 23.5 percent; and containing 37.5 phr of aromatic oil (50 phr of rubber in the compounds). Rubber with a high content of cis-1,4-polybutadiene The Goodyear Tire & Rubber Company. 3. Type N330. 4 Natural ground calcium carbonate obtained as Atomite ECC America.

Table 4 Compounds F G H I J K Carbon black 40 40 40 30 30 30 Calcium Carbonate 40 40 40 50 50 50 Yes69 (50%) Dithiopropionic Acid 2.5 Torque Torque Max. 46.0 53.0 45.0 44.0 46.4 52.3 Torque Min. 4.0 5.0 5.1 11 T90, minutes 9.5 16.0 10.0 10.0 17.5 21.5 T25, minutes 5.5 8.5 5.5 5.5 9.0 15 .: Stress Resistance, Mpa 7.0 9.5 5.4 7.5 6.7 Elongation at Break,% 211 269 180 209 310 212 M100, Mpa 2.9 3.2 3.4 2.3 2.2 2.9 Rebound, TA 57.5 53.4 57.8 62.3 57.2 63.1 Bouncing, hot 67.2 69.7 67.9 68.6 72.3 70.2 Hardness, AT 62.5 67.1 65.8 60.5 61.2 61.9 Hardness, hot 61.7 64.8 65.0 59.2 59.4 61.7 Abrasion of DIN 216 205 208 274 243 240 EXAMPLE III The rubber compounds containing the styrene / butadiene rubber prepared by solution polymerization (S-SBR) and the natural rubber and reinforced with carbon black and calcium carbonate were prepared in a three-stage Banbury mixer (Table 5) and reference is made to the same Exp L, M and N. The curing behavior in the cured properties for these compounds are shown in Table 6. The compounds (rubber compositions) were cured at a temperature of about 150 ° C for about 36 hours. minutes Compound L contains the Si69 coupling agent, while Compound M also contains dithiodipropionic acid and Compound N also contains nicotinamide. Compounds M and N were found to exhibit improved (increased) tensile strength at break and a modulus greater than 300 percent and hardness than Compound L.

Table 5 L M N First No Producer S-SBR 50.0 50.0 50.0 Natural Rubber 50.0 50.0 50.0 Carbon Black 43.0 43.0 43.0 Antioxidant 2.2 2.2 2.2 Processing aids 5.5 5.5 5.5 Zinc Oxide 3.5 3.5 3.5 Fatty Acid 2.0 2.0 2.0 Second Non-Productive Calcium Carbonate "17.0 17.0 17.0 Coupling Agent of Si69 (50%) 3.5 3.5 3.5 Dithiodipropionic acid 2.0 Nicotinamide 2.0 Productive Sulfenamide Accelerator 1.0 1.0 1.0 Antioxidant 1.2 1.2 1.2 Sulfur 1.5 1.5 1.5 Diphenylguanidine 0.4 0.4 0.4 1. Styrene / butadiene copolymer rubber prepared by solution polymerization obtained as SLF 1216 from The Goodyear Tire & Rubber Company. 2. N-330. 3. Natural ground calcium carbonate, obtained as "Car-nel-Wite" from Genstar Company.

Table 6 Compounds M N Yes69 3. 5 3. 5 3. 5 Dithiodipropionic Acid 2.0 Nicotinamide 2.0 Torque Torque Max 38.0 41.5 42.0 Torque Torque Min 5.0 5.0 5.5 T90, minutes 14.5 23.5 17.0 T25, minutes 6.5 7.3 4.3 Stress Resistance, Mpa 15.8 18.0 17.0 Elongation at break,% 447 464 450 M300, Mpa 10.2 11.6 11.1 Rebound, TA 52.4 53.3 49.7 Bouncing, hot 67.4 66.5 65.7 Hardness, TA 56.9 61.7 59.8 Hardness, hot 55.0 58.4 57.2 Abrasion of DIN 151 148 150 EXAMPLE IV Rubber compounds containing styrene / butadiene rubber prepared by emulsion polymerization (E-SBR), cis-1, 4-polybutadiene rubber and optionally, epoxidized natural rubber were prepared in a similar manner to Example I with a reinforcement of carbon black, optionally together with calcium carbonate and are identified in Table 7 as Exp Q, R and S with Ctrl P being represented as a Control.

Table 7 First No Productive CtrlP Exp Q Exp R Exp S E-SBR 50 50 40 40 Polybutadiene 50 50 50 50 ENR 25"10 10 Carbon Black 50 35 35 35 Calcium carbonate '0 15 15 15 Processing Oil 5 Zinc Oxide Fatty Acid Antioxidant Coupling Agent of Si69 (50%) Second No Productive First No Productive mixed again without additional materials added Productive Accelerator of _ Sulfenamide 1.2 1.5 1.5 1.5 Diphenilguanidine 1.0 1.0 1.0 1.0 Sulfur 1.0 1.2 1.2 1.0 1. Emulsion-polymerized butadiene / styrene rubber obtained as SOLFLEX (R) 1502 from The Goodyear Tire & Rubber Company. 2. The cis-1,4-polybutadiene obtained as BUDENE (R) 1207 from The Goodyear Tire & Rubber Company. 3. Epoxidized natural rubber obtained as ENR 25 (25 by - - epoxidized level percent) of a Malaysian rubber company. Natural ground calcium carbonate, treated on its surface obtained from Omya, from Omya BSH.

The rubber compositions were cured under high pressure and elevated temperature (about 150 ° C) compositions for about 36 minutes. The physical properties for the rubber compositions are shown in the following Table 8.

Table 8 Ctrl P Exp Q Exp R Exp S ENR 10 10 Carbon Black 50 35 35 35 CaC03 15 15 15 Yes69 (50%) Torque Torque Max. 42.2 40.4 41 42.4 Torque Min. 6.3 T90, minutes 17.5 18.5 14 17.5 T25, minutes 12.3 13.8 10.3 10.8 Resistance to Tension, MPa 18.1 12.12 12.51 13.72 Elongation at Break,% 488 446 464 470 M100, Mpa 2.24 1.89 1.98 2.07 M300, Mpa 10.23 7.34 7.26 7.97 Rebound, TA 46.7 57.1 52.5 54.6 Bouncing, hot 58.1 66.1 63.8 65.4 Hardness, TA 65.3 59.8 61.3 60.7 Hardness, hot 59.3 55.2 56.5 57.5 Abrasion of DIN 64 105 103 88 The value of DIN Abrasion (the lower is better) for Exp. S, compared to Ctrl P indicating that the combination of the epoxidized natural rubber and the coupling agent of Si69, together with the carbonate of calcium, is predictive of better (improved) tread for rubber composition when used as a rim tread surface. Although 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 or scope of the invention.

Claims (14)

CLAIMS:

1. A rubber composition characterized in that it comprises (A) 100 parts by weight of an elastomer consisting essentially of (1) at least one diene-based elastomer, or (2) a combination of diene-based elastomer and an elastomer a epoxidized diene base, (B) from 15 to 45 phr of a particulate reinforcement selected from carbon black and / or precipitated silica, silica has silanol groups on the surface thereof, (C) from 5 to 50 phr of particulate calcium carbonate and (D) at least one modifier consisting of at least one dithiodipropionic acid, nicotinamide and bis-3 (trialkoxysilylalkyl) polysulfide, which has an average of 2.1 to 4 sulfur atoms in its bridge Or polysulphide connection, and wherein these alkyl groups contain from two to four carbon atoms.

2. The rubber composition of the claim 1 characterized in that the epoxidized rubber is epoxidized natural cis-1, 4-polyisoprene rubber.

3. The rubber composition of claim 1, characterized in that the elastomers are from 5 to 30 phr of an elastomer based on epoxidized diene as epoxidized natural rubber containing from 20 percent to 50 percent epoxidation and from 95 percent at 70 phr of the diene-based elastomer.

The rubber composition of any of the foregoing claims, characterized in that the diene-based rubber consists of at least one cis-1,4-polyisoprene rubber, 3,4-polyisoprene rubber, copolymer rubbers, and the like. styrene / butadiene, isoprene / butadiene copolymer rubbers, styrene / isoprene copolymer rubbers, styrene / isoprene / butadiene terpolymer rubbers, cis-1, 4-polybutadiene rubber, 1, 4-polybutadiene trans rubber (70 percent to 95 percent trans), low vinyl polybutadiene rubber (10 to 30 percent vinyl), medium vinyl content polybutadiene rubber (30 to 50 percent vinyl), rubber polybutadiene of high vinyl content (from 50 to 90 percent vinyl) and butadiene / acrylonitrile copolymers prepared by emulsion polymerization.

5. The composition of claim 1, characterized in that the elastomers exclude the epoxidized natural rubber.

The composition of any of the foregoing claims characterized in that the composition excludes silica and contains 15 to 30 phr of carbon black and wherein the total of carbon black and calcium carbonate is 30 to 65 phr.

The composition of any of the preceding claims 1 to 4, characterized in that claims 1 to 4 contain 13 to 35 phr of silica and 2 to 20 phr of carbon black.

The composition of any of the foregoing claims, characterized in that the carbon black is a combination of high-strength carbon black that is selected from carbon black NllO and N220 and low-carbon black carbon which are selected from blacks of carbon N550 and N660 with the condition that 60 percent to 80 percent by weight of carbon black is carbon black with a high content of reinforcement.

The composition of any of the foregoing claims, characterized in that the modified * r is selected from at least one dithiodipropionic acid, nicotinamide and a bis-3- (trialkoxysilylalkyl) polysulfide having an average of 2.1 to 4 sulfur atoms in its bridge or polysulfidic connection.

10. The rim of any of the preceding claims, characterized in that the modifier is dithiodipropionic acid.

11. The composition of any of the preceding claims, 1 to 9 characterized in that the modifier is nicotinamide.

The composition of any of the preceding claims 1 to 9 characterized in that the modifier is bis-3 (trialkoxysilylalkyl) polysulfide having an average of 2.1 to 4 sulfur atoms in its connection or polysulfide bridge and wherein the alkoxy groups they are selected from methoxy and ethoxy groups and the alkyl groups are selected from ethyl groups, propyl and butyl.

The rim of any one of claims 1 to 9, characterized in that the modifier is bis-3 (triethoxysilylpropyl) polysulfide having an average of 2.1 to 4 sulfur atoms in its bridge or polysulfidic connection.

14. A tire characterized in that it has a component of the composition of any of the preceding claims 1 to 14.