MXPA99006352A - Process to improve the properties of the mol recycled rub - Google Patents

Abstract

A process is presented that includes (a) the homogeneous dispersion of tris (2-aminoethyl) amine in a recycled rubber having an individual particle size no greater than 420 microns, (b) the mixture of recycled rubber treated with unvulcanized rubber and (c) vulcanization of the mixture of hu

Description

PROCESS FOR IMPROVING THE PROPERTIES OF GRINDING RECYCLED HUV BACKGROUND OF THE INVENTION It is frequently desired to recover or recycle vulcanized rubber. The vulcanized rubber generally has the form of a manufactured article such as, for example, a pneumatic tire, industrial or power transmission belt, hose and the like. Discarded pneumatic tires are an especially large source of vulcanized rubber of this type. Vulcanized rubber is conventionally shredded and recovered or recycled through various processes, or a combination of processes, which may include physical breakdown, grinding, chemical breakdown, devulcanization and / or cryogenic grinding. If the vulcanized rubber contains wire or textile fiber reinforcement, then it is generally removed by several processes which may include magnetic separation, air aspiration and / or an air flotation step. In this description, the terms "recycling" and "recycled rubber" are used in a relatively interchangeable manner and relate to both vulcanized rubber and devulcanized rubber, which is described more precisely below. It is important to note that devulcanized recycled rubber or devulcanized recycling (sometimes referred to as recovery rubber) refers to rubber that has been vulcanized after being substantially or partially devulcanized. The resulting recycle rubber that has been devulcanized is a polymeric material that has approximately the appearance of unvulcanized rubber but has marked differences and different properties with non-vulcanized rubber. First, it is a rubber that, in essence, is partially vulcanized from a mixture of polymer units of various constructions that differ from both unvulcanized rubber and vulcanized rubber. Second, recycled rubber, unlike conventional non-vulcanized rubber, is also a complex mixture of largely unknown polymer (s), compositional ingredients, possibly textile fiber parts, and the like. It has been observed that, after the addition of sulfur and accelerator to recycle the rubber, followed by its revulcanization, the resulting physical properties, such as tension and elongation, are usually lower than the corresponding properties of the original vulcanized rubber from which is derived. It has also sometimes been observed that the exposed edges of sacks or sheets of recycle rubber have a tendency to bend upwards, apparently as a result of oxidation degradation, probably due to a deficiency of antidegradants that would normally be present in an adequate amount in the rubber. compound, not vulcanized. SUMMARY OF THE INVENTION The present invention relates to a process for improving the properties of ground recycled rubber. DETAILED DESCRIPTION OF THE INVENTION A process for improving the properties of ground recycled rubber is presented, comprising: (a) the homogeneous dispersion of 0.18 to 10.0 phr of tris (2-a-methyethyl) amine in a recycled rubber compound having a individual particle size no greater than 420 microns to form a treated recycled rubber compound; (b) mixing from 1 to 40 parts by weight of said recycled rubber compound treated with 60 to 99 parts by weight of at least one uncured rubber in order to form a recycled / uncured rubber compound; (c) heating the recycled / non-vulcanized rubber compound for a sufficient time and at a temperature sufficient to vulcanize all of the rubber in the recycled / uncured rubber compound. The recycle rubber must have a particle size no greater than 420 microns (40 mesh). Any particle larger than this size would make impractical the subsequent mixing of the unvulcanized rubber. Generally, the individual particle size should be no greater than 250 microns (60 mesh) and preferably less than 177 microns (80 mesh). Preferably, the individual particle size is located within a range of 250 microns (60 mesh) to 74 microns (200 mesh). The tris (2-aminoethyl) amine is dispersed in the recycle rubber in an amount that is within a range of 0.18 to 10.0 phr. Preferably, the level of dispersed tris (2-aminoethyl) amine is within a range of 0.36 to 5.0 phr. The tris (2-aminoethyl) amine can be dispersed directly in the recycle rubber or be suspended or dissolved in a solvent and then applied to the recycled rubber. Representative examples of these solvents include acetone, chloroform, dichloromethane, carbon tetrachloride, hexane, heptane, cyclohexane, xylene, benzene, dichloroethylene, dioxane, diisopropyl ether, tetrahydrofuran and toluene. Preferably, the solvent is acetone. The recycled rubber with the tris (2-aminoethyl) amine dispersed within or on it, is known interchangeably herein as "treated recycled rubber". The treated recycled rubber is mixed with unvulcanized rubber. From 1 to 40 parts by weight of the treated recycled rubber is mixed with 60 to 99 parts by weight of at least one unvulcanized rubber to form an unvulcanized rubber / recycled rubber compound. Preferably, from 2 to 30 parts by weight of the treated recycled rubber is mixed with 70 to 98 parts by weight of at least one unvulcanized rubber. Representative examples of unvulcanized rubber that can be blended with the treated recycled rubber include natural rubber and various synthetic rubbers. Representative synthetic polymers include the products of homopolymerization of butadiene and its homologs and derivatives, such as for example methyl-butadiene, dimethylbutadiene and pentadiene as well as copolymers such as those formed from butadiene or its homologs or derivatives with other organic unsaturated compounds. Among the latter are acetylenes, for example, acetylene vinyl; olefins, for example, isobutylene, which is copolymerized with isoprene to form butyl rubber, vinyl compounds, for example, acrylic acid, acrylonitrile (which is bristly with butadiene to form NBR), methacrylic acid and styrene, the latter polymerizing with butadiene to form SBR, as well as vinyl esters and various unsaturated aldehydes, ketones and ethers, for example, acrolein, methylisopropenylketone and vinylethyl ether. Also included are the various synthetic rubbers prepared by the homopolymerization of propylene and the copolymerization of isoprene and other iolefins in various unsaturated organic compounds. Synthetic rubbers such as 1,4-cis-polybutadiene and 1,4-cis-polyisoprene and similar synthetic rubbers are also included. Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including trans- and cis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene), halobutyl rubber, copolymers of halobutyl rubbers of 1, 3-butadiene or isoprene with monomers such as styrene, acrylonitrile and methyl methacrylate, as well as ethylene / propylene / diene monomer (EPDM) and particularly ethylene / propylene / dicyclopentadiene terpolymers. Preferred rubbers for use in the present invention are natural rubber, polybutadiene, polyisobutylene, EPDM, butadiene-styrene copolymer, cis-1,4-polyisoprene, styrene-isoprene copolymer, butadiene-styrene-isoprene copolymer, polychloroprenes and mixtures thereof. The rubbers can be at least two of the diene-based rubbers. For example, a combination of two or more rubbers is preferred such as, for example, rubber 1, 4-polyisoprene rubber (natural or synthetic, even though natural rubber is preferred), rubber of 3,4-polyisoprene, styrene / isoprene rubber / butadiene, styrene / butadiene rubbers derived from emulsion and solution polymerization, cis 1,4-polybutadiene rubbers as well as butadiene / acrylonitrile copolymers prepared by emulsion copolymerization.

In one aspect of this invention, a styrene / butadiene derivative emulsion polymerization (E-SBR) having a relatively conventional styrene content of about 20 to about 28% bound to styrene or, in the case of some applications, may be employed. , an E-SBR having a medium to relatively high bound styrene content, namely, a bound styrene content of from about 30 to about 45%. The relatively high styrene content of about 30 to about 45% for E-SBR can be considered beneficial for the purpose of increasing the tensile strength, or slip, of the tire floor. The presence of the E-SBR itself is considered beneficial for the purpose of increasing the processability of the uncured elastomer composition mixture, especially as compared to an SBR prepared by solution polymerization (S-SBR). By E-SBR prepared by emulsion polymerization, it is understood that styrene and 1,3-butadiene are copolymerized in the form of an aqueous emulsion. These are well-known processes by experts in the field. The bound styrene content can vary, for example, from about 5 to about 50%. In one aspect, the E-SBR may also contain acrylonitrile to form a terpolymer rubber, such as E-SBAR, in amounts, for example, from about 2 to about 30% by weight of acrylonitrile attached in the terpolymer. Styrene / butadiene / acrylonitrile copolymer oils prepared by emulsion polymerization containing from about 2 to about 40% by weight of acrylonitrile bound in the copolymer are also contemplated as diene-based rubbers for use in this invention. The SBR prepared by solution polymerization (S-SBR) typically has a styrene content bound within a range of about 5 to about 50, preferably about 9 to about 36%. The S-SBR can be conveniently prepared, for example, by means of lithium organ catalysis in the presence of an organic hydrocarbon solvent. One purpose for the use of S-SBR is to improve the rolling resistance of the tires as a result of a lower hysteresis when used in a tire floor composition. The rubber of 3,4-polyisoprene (3,4-PI) is considered beneficial for the purpose of increasing tire traction when used in a tire floor composition. The 3,4-PI and its use is described in greater detail in U.S. Patent No. 5,087,668 which is incorporated herein by reference. Tg refers to the glass transition temperature which can be conveniently determined by means of a differential scanning calorimeter at a heating rate of 10 ° C per minute. The rubber of cis 1,4-polybutadiene (BR) is considered beneficial for the purpose of increasing the wear resistance of the tire floor. Said BR can be prepared, for example, by the polymerization in organic solution of 1,3-butadiene. The BR can be conveniently characterized, for example, because it has at least 90% cis 1,4 content. The cis 1,4-polyisoprene and natural rubber of cis 1,4-polyisoprene are well known to those skilled in the rubber art. As will be observed by a person skilled in the art, any of the above-mentioned non-vulcanized rubbers may be of the same type of rubber or of a rubber type different from that found in the ground recycled rubber. The term "phr" as used herein, and in accordance with conventional practice, refers to "parts by weight of a respective material per 100 parts by weight of rubber, or elastomer." In order to cure the rubber composition of the present invention, a sulfur vulcanization agent is added. Examples of suitable sulfur vulcanization agents include elemental sulfur (free sulfur) or sulfur donor vulcanization agents, for example, an amine disulfide, polymeric polysulfide or sulfur olefin adducts. Preferably, the sulfur vulcanization agent is elemental sulfur. The amount of sulfur vulcanization agent will depend on the type of rubber and the particular type of sulfur vulcanization agent employed. In general terms, the amount of sulfur vulcanizing agent is within a range of about 0.1 to about 5 phr, being preferred within a range of about 0.5 to about 2. Conventional rubber additives can be incorporated into the rubber raw material of the present invention. The additives usually employed in the first rubber material include fillers, plasticizers, waxes, processing oils, peptizers, retardants, antiozonants, antioxidants and the like. The total amount of filler that can be employed can vary within a range of about 30 to about 150 phr, being preferred within a range of about 45 to about 100 phr. The fillers include clays, calcium carbonate, calcium silicate, titanium dioxide and carbon black. Representative smoke blacks commonly employed in rubber include N110, N220, N231, N234, N242, N293, N299, S315, N326, N330, M332, N339, N343, N347, N351, N358, N375, N472, N539, - N582 , N630, N642, N660, N754, N762, N765, N774, N990 and N991. Plasticizers are usually employed in amounts ranging from about 2 to about 50 phr, being preferred within a range of about 5 to about 30 phr. The amount of plasticizer used will depend on the desired softening effect. Examples of suitable plasticizers include oils from aromatic extracts, oil softeners including asphaltenes, pentachlorophenol, saturated and unsaturated hydrocarbons and nitrogen bases, coal tar products, coumarona-indene resins and esters such as dibutyl phthalate and tricresol phosphate. Typical peptizers can be, for example, pentachlorothiophenol and dibenzamidophenyl disulfide. Such peptizers are used in amounts that are within a range of 0.1 to 1 phr. Common waxes that may be employed include paraffin waxes and microcrystalline mixtures. Such waxes are used in amounts that fall within a range of about 0.5 to 3 phr. Materials used to form accelerator-activating compounds include oxides of metals such as zinc oxide and magnesium oxide which are used in combination with acidic materials such as fatty acid, for example, fatty acids of wood pulp oil, acid stearic, oleic acid and the like. The amount of metal oxide can be located within a range of about 1 to about 14 phr, with a range of about 2 to about 8 phr being preferred. The amount of fatty acid that can be employed can be located within a range of about 0 phr to about 5.0 phr, with a range of about 0 phr to about 2 phr being preferred. Accelerators are used to control the time and / or temperature required for vulcanization and in order to improve the properties of the vulcanized product. In one mode, a single accelerator system can be used; that is, a primary accelerator. The primary accelerator (s) can be used in total amounts that are within a range of about 0.5 to about 4, preferably within a range of about 0.8 to about 2.0 phr. In another embodiment, combinations of a primary accelerator with a secondary accelerator can be employed, using the secondary accelerator in a smaller amount, equal to or greater than the primary accelerator. It can be expected that combinations of these accelerators will produce a synergistic effect on the final properties and be in some way better than the products produced by the use of any of the accelerators alone. In addition, delayed action accelerators which are not affected by normal processing temperatures can be employed but produce a satisfactory cure at ordinary vulcanization temperatures. Vulcanization retardants can also be used. Suitable types of accelerators that can be employed in the present invention are amines, disulfides, guanidines, thiureas, thiazoles, thiurams, 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, disulfide or a thiuram compound. The rubber compounds of the present invention may also contain a curing activator. A representative curing activator is methyltrialkyl (C8-C? O) ammonium chloride commercially available under the trademark Adogen (MR) 464 from Sherex Chemical Company of Dublin, Ohio. The amount of activator can be used within a range of 0.05 to 5 phr. Siliceous pigments can be employed in the rubber compound applications of the present invention, including pyrogenic siliceous pigments and precipitates (silica), even though it is preferred to employ precipitated silicas. The siliceous pigments preferably employed in this invention are precipitated silicas such as, for example, the silicas obtained by the acidification of a soluble silicate, for example sodium silicate. Such silicas can be characterized, for example, because they have a BET surface area, as measured using nitrogen gas, which is preferably within the range of about 40 to about 600, more usually within a range of about 50 to about 300. square meters per gram. The BET method for measuring surface area is described in the Journal of the American Chemical Society, Volume 60, page 304 (1930). The silica can also be characterized typically because it has an absorption value of dibutyl phthalate (DBP) within a range of about 100 to about 400, and more usually within a range of about 150 to about 300. It can be expected that the silica has an average final particle size, for example, within the range of 0.01 to 0.05 miera as determined by electron microscopy, even though the silica particles may be even smaller, or possibly larger, in size. Various commercially available silicas can be considered for use in this invention as for example without limitation, silicas commercially available from PPG Industries, under the trademark Hi-Sil with designations 210, 243, etc; silicas available in Rhone-Poluenc, for example, with the designations Z1165MP and Z165GR as well as silicas available from Degussa AG, for example, with designations VN2 and VN3, etc.

Generally speaking, the amount of silica can be within a range of 5 to 120 phr. The amount of silica will generally be within a range of about 5 to 120 phr. Preferably, the amount of silica will be within a range of 10 to 30 phr. A class of materials for forming compounds known as retardants are commonly employed. The italic anhydride, salicylic acid, sodium acetate and thiophthalimide of N-cyclohexyl are known retarders. The retardants are usually used in an amount that is within a range of about 0.1 to 0.5 phr. Conventionally, the antioxidants and sometimes the antiozonants, known below as antidegradants, are added to the rubber. Representative antidegradants include monophenols, bisphenols, thiobisphenols, polyphenols, hydroquinone derivatives, phosphites, thioesters, naphthyl amines, diphenyl-p-phenylenediamines, diphenylamines and other diarylamine derivatives, para-phenylenediamines, polymerized trimethyldihydroquinoline and mixtures thereof. Specific examples of such antidegradants are presented in the Vanderbilt Rubber Handbook (1990), pages 282-286. Antidegradants are generally employed in amounts of about 0.25 to about 5.0 phr with a range of about 1.0 to about 3.0 phr being preferred.

The rubber compound of the present invention can be used as a wire coating or flange coating for use on a rim. Any cobalt compound known in the art to promote rubber adhesion on the metal can be employed. Thus, suitable cobalt compounds that may be employed include cobalt salts of fatty acids such as, for example, stearic, palmitic, oleic, linoleic acid and the like; cobalt salts of aliphatic or alicyclic carboxylic acids having from 6 to 30 carbon atoms; cobalt chloride, cobalt naphthenate, cobalt neodecanoate, cobalt carboxylate and an organo-cobalt-boron complex commercially available under the designation Manobond C in Yrough and Loser, Inc., Trenton, New Jersey. It is believed that Manobond has the structure: O II Co-O-C-R I or o or il I II R-C-0-Co-0-B-0-Co-0 C-R where R is an alkyl group having from 9 to 12 carbon atoms. The amounts of cobalt compounds that can be employed depend on the specific nature of the selected cobalt compound, particularly the amount of cobalt metal present in the compound. Since the amount of cobalt metal varies considerably in the cobalt compounds that are suitable for use, it is appropriate and convenient to base the amount of the cobalt compound employed in the amount of cobalt metal that is desired in the finished composition. The amount of the cobalt compound can be located within a range of about 0.1 to 2.0 phr. Preferably, the amount of cobalt compound can be located within a range of about 0.5 to 1.0 phr. When employed, the amount of cobalt compound present in the composition should be sufficient to provide from about 0.01% to about 0.35% by weight of cobalt metal based on the total weight of the original rubber composition with the preferred amounts being located within from a range of about 0.03% to about 0.2% by weight of cobalt metal based on the total weight of the original composition. The vulcanizable sulfur rubber compound is cured at a temperature that is within a range of about 125 ° C to 180 ° C. Preferably, the temperature is within a range of about 135 ° C to 160 ° C. The mixture of the rubber compound can be carried out by various methods known in the art of rubber mixing. For example, the ingredients are typically mixed in at least two stages, namely, at least one non-productive step followed by a productive mixing step. The final curing agents are typically mixed in the final stage which is conventionally known as the "productive" mixing stage where mixing at a temperature typically occurs., or else the last temperature, lower than the mixing temperature or mixing temperatures of the previous non-productive mixing stage or the previous non-productive mixing stages. The terms of "non-productive" and "productive" mixing stages are well known to those skilled in the art of rubber mixing. The rubber compositions can be used for the formation of a compound with reinforcing material as for example in the case of the manufacture of rims, bands or hoses. Preferably, the composition of the present invention is in the form of a rim and more especially as a component of a rim, including, the floor, the wire liner, the rim lining, the side wall, the apex, the float surface and the tarpaulin. Example 1 4.4 grams of tris (2-aminoethyl) amine dissolved in 325 ml of acetone was added to a 1 liter open top glass reactor containing 220 grams of ground recycle rubber GF80 from Rouse Rubber Industries, Inc. Vicksburg, Mississippi. In accordance with the screen analysis on the specification sheet, GF80 contains 88% by weight of particles passing through a 100 mesh, 95% by weight of particles passing through 80 mesh and 100% by weight of particles passing through a 60 mesh. The TGA analysis for GF80 is 13.74% by weight of volatile substances, 6.74% by weight of ash, 29.55% of carbon black and 49.94% by weight of rubber hydrocarbon. The ground rubber was agitated as the solvent was being distilled at room temperature under a reduced pressure of 29 inches Hg to homogeneously disperse the tris (2-aminoethyl) amine in the ground recycle rubber. The treated recycled product was dried at a temperature of 100 ° C for 4 hours in a drying oven. EXAMPLE 2 Three rubber formulations were prepared to compare and contrast the importance of the use of ground recycled rubber and recycled rubber ground with tris (2-aminoethyl) amine. Each rubber formulation contained 60 parts by weight of polymerized SBR in solution, 25 parts by weight of polybutadiene and 15 parts by weight of 3,4 polyisoprene. The SBR is marketed by Goodyear Tire &; Rubber Company as Solflex (MR) 1216. Polybutadiene rubber is marketed by Goodyear Tire & Rubber Company as Budene (MR) 1207. The 3.4 polyisoprene rubber was obtained from Goodyear Tire & Rubber Company. Each rubber formulation also contained the same conventional amounts of carbon black, processing oil, fatty acids, antidegradants, waxes, zinc oxide, primary and secondary accelerators, and sulfur. Each formulation was different by adding ingredients listed in Table 1. The rubber formulations were prepared in a two-stage Banbury (MR) mixer. All parts and percentages are by weight unless otherwise indicated. Samples 1 and 2 are controls and sample 3 represents the present invention. Curing properties were determined using a Monsanto oscillating disc rheometer operated at a temperature of 150 ° C and 100 cycles per minute. A description of oscillating disc rheometers can be found in the Vanderbilt Rubber Handbook edited by Robert O. Ohm (Norwalk, Conn., R.T. Vanderbilt Company, Inc., 1990), pages 554-557. The use of this cure meter and the standardized values read from the curve are specified in ASTM D-2084. A typical curing curve obtained on an oscillating disc rheometer is shown on page 555 of the 1990 edition of the Vanderbilt Rubber Handbook. In an oscillating disc rheometer of this type, composite rubber samples are subjected to an oscillating cutting action at constant amplitude. The torque of the oscillating disc integrated in the material being tested that is required to oscillate the rotor at the vulcanization temperature is measured. The values obtained by using this curing test are very significant since changes in the rubber or in the recipe of the composition are detected very easily. It is clear that it is normally helpful to have a fast curing speed. The following Table 1 reports the curing properties determined from curing curves obtained for prepared rubbers. These properties include a minimum torque (minimum torque), a maximum torque (maximum torque), the difference between the maximum torque and the minimum torque (delta torque), the torque of final torque (final torque), minutes to an increase of 1% of torque (ti), minutes to an increase of 25% of torque (t25), minutes to an increase of 50% of torque torque (t50), minutes up to a 75% increase in torque (t75) and minutes up to a 90% increase in torque (t90). Table I Sample No. 1 2 3 Recovery rubber 1 0 20. 00 0 Recovery rubber2 with 0 0 20. 41 tris (2-aminoethyl) amine Minimum torques 8.8 10.2 10.4 Maximum torque 36.3 33.6 35.9 Delta torque 27.5 23.4 25.5 Final torque 36.0 33.4 35.2 t 1 (min) 6.7 6.2 3.2 t 25 (min) 9.3 8.1 4.2 t 50 (min) 10.6 9.3 5.0 t 75 (min) 12.7 11.7 6.2 t 90 (min) 16.5 15.5 8.2 ATS 19.5 min / 150 ° C Module of 100% 2.17 1.87 2.04 Module of 150% 3.53 2.89 3.25 Module of 200% 5.41 4.69 4.96 300% module 9.82 8.30 9.23 Resistance to tension (MPa) 14.61 14.10 12.87 Elongation (%) 449 487 422 Energy, (J) 100.58 104.01 82.28 Hardness at room temperature 62.2 61.7 62.9 Hardness at 100 ° C 56.3 54.2 56.6 Bounce at room temperature 40.7 40.6 41.4 Bounce at 100 ° C 58.3 55.3 56.1 Specific gravity 1.103 1.107 1.107 ^ F-dO2prepared in example 1 When the unvulcanized rubber (sample 1) is treated with 20.0 parts of recycled rubber (sample 2) the delta torque values decrease from 27.5 to 23.4. The addition of recycled rubber treated with tris (2-aminoethyl) amine (sample 3) results in a restoration of most of the decrease in delta torque (from 27.5 to 25.5). The high delta torque value is an indication of increased curing and cross-linking density in rubber and suggests that recycled rubber is cured in unvulcanized rubber. The higher final values of torque for sample 3 compared to sample 2 indicate the superiority of the present invention. Higher crosslinking densities are shown for the present invention (sample 3) when values are observed for a 300% modulus, 200% modulus, 150% modulus and 100% modulus.

Claims (1)

1. CLAIMS. A process for improving the properties of ground recycled rubber, characterized by: (a) the homogeneous dispersion of 0.18 to 10.8 phr of tris (2-aminoethyl) amine in a recycled rubber compound having an individual particle size no greater than 420 microns to form a treated recycled rubber compound; (b) mixing from 1 to 40 parts by weight of said recycled rubber compound treated with 60 to 99 parts by weight of at least one uncured rubber to form a recycled / uncured rubber compound; (c) heating the recycled / non-vulcanized rubber compound for a sufficient time and at a temperature sufficient to vulcanize all of the rubber in the recycled / uncured rubber compound. . The process of claim 1 characterized in that the tris (2-aminoethyl) amine is dispersed in a solvent before being homogenously dispersed in said vulcanized rubber. . The process of claim 2 characterized in that said solvent is selected from the group consisting of acetone, chloroform, dichloromethane, carbon tetrachloride, hexane, heptane, cyclohexane, xylene, benzene, dichloroethylene, dioxane, diisopropyl ether, tetrahydrofuran and toluene. 4. The process of claim 1 characterized in that the particle size is not greater than 250 microns. 5. The process of claim 1 characterized in that the particle size is within a range of 250 microns to 74 microns. 6. The process of claim 1, characterized in that it is dispersed homogeneously from 0.36 to 5.0 phr of tris (2-aminoethyl) amine. 7. The process of claim 1, characterized in that the tris (2-aminoethyl) amine is dispersed directly in the recycle rubber. The process of claim 1 characterized in that said unvulcanized rubber is selected from the group consisting of natural rubber, polybutadiene, polyisobutylene, EPDM, butadiene-styrene copolymers, cis-1,4-polyisoprene, styrene-isoprene copolymers , butadiene-styrene-isoprene copolymers, polychloroprenes and mixtures thereof. 9. The process of claim 1 characterized in that said unvulcanized rubber is selected from the group consisting of polybutadiene, butadiene-styrene copolymers and mixtures thereof. The process of claim 1 characterized in that from 2 to 30 parts by weight of said recycled rubber compound treated with 70 to 98 parts by weight of said unvulcanized rubber compound is mixed.