MXPA06006390A - Process for the preparation of a thermoplastic elastomeric vulcanizate - Google Patents

Abstract

The invention deals with a process for the preparation of a thermoplastic elastomeric vulcanizate, based on a polyolefin and a rubber. The rubber is vulcanized with an organic peroxide having at least one terminal carbon-carbon bond in the molecule. As a result, blooming effects are reduced and physical properties are improved.

Description

PROCESS FOR THE PREPARATION OF A THERMOPLASTIC ELASTOMERIC VULCANIZATION FIELD OF THE INVENTION The present invention concerns a process for the preparation of a thermoplastic elastomeric vulcanizate (TPV) comprising a mixture of a polyolefin and a vulcanized rubber, in which the vulcanization of the rubber is carried out at elevated temperature under the influence of a peroxide. Such a process is described in EP-A-72,203.

BACKGROUND OF THE INVENTION The emergence of thermoplastic elastomers (TPEs) in the 1950s provided a new horizon in the field of polymer science and technology. A TPE is a gummy material with properties and functional results similar to those of conventional vulcanized rubber at room temperature, even if it can be processed in a melting condition such as a thermoplastic polymer at elevated temperature. The fate of TPEs based on polyolefin / thermoplastic polymer compositions has grown along two different product lines or classes indistinctly: one class consists of simple mixtures and is commonly referred to as thermoplastic elastomeric olefins (TEO); in the other class, the rubber phase is (dynamically) vulcanized, giving rise to a thermoplastic vulcanizate (TPV). Morphologically, the TPVs are characterized by the presence of finely dispersed crosslinked rubber particles distributed in a continuous thermoplastic matrix. If the elastomeric particles of such a mixture are sufficiently small and if they are sufficiently vulcanized, then the physical and chemical properties of the mixture are generally improved. TPVs based on polypropylene (PP) and rubber-EPDM mixtures are the most important representative of this class of materials. Several crosslinking agents are used to cross-link EPDM rubber into PP / EPDM mixtures. Each of the crosslinking systems has its own merit and demerit. The crosslinking systems often used for these purposes are activated phenol-formaldehyde resins, commonly known as resoles. However, there were two important problems associated with TPVs based on these resins: (a) hygroscopic, even at room temperature; the absorbed moisture must be completely removed, the high-temperature drying procedures before processing to eliminate product defects; and (b) very dark brown appearance, which is difficult to conceal and sometimes needs the use of two different pigment systems to achieve the desired color. These disadvantages of the resoles impose a demand for alternative cross-linking agents. The cross-linking of rubber with peroxides for more than fifty years has been well known. The general advantages of peroxides as crosslinking agents are their ability to crosslink unsaturated and unsaturated elastomers; Good resistance to high temperatures and good elastic behavior (setting by compression), particularly at high temperatures, do not pick up moisture, and do not stain or discolor the finished products. A co-agent is often used to improve the efficiency of peroxide crosslinking by forming a more hermetic network. Along with the advantages of peroxides, there are also disadvantages. Depending on the composition of the peroxide applied, the decomposition products are more or less volatile. These often provide a typical odor, show an efflorescence effect or can be extracted from the solvent-crosslinked compound. For example, the sweet smell typical of acetophenone, one of the decomposition products of dicumyl peroxide (DCP) is well known. The efflorescence phenomenon also occurs due to the formation of dihydroxy isopropyl benzene from the decomposition of di (tert-butylperoxyisopropyl) -benzene. The use of a peroxide also negatively influences the physical properties of the final POS, when the peroxide also reacts with the polyolefin used as the matrix. In the case where the polyolefin is a polyethylene, the peroxide can cause crosslinking of the polyethylene, as a result of which the processability is reduced. In the case where the polyolefin is a polypropylene, the peroxide can cause degradation of the polymer chain, with detrimental effect on the mechanical properties. To overcome the above problems, a new process was found that reduces or even eliminates them.

SUMMARY OF THE INVENTION The process according to the present invention is characterized in that the peroxide which is used for the vulcanization of the rubber is an organic peroxide having at least one terminal carbon-carbon double bond in the molecule. Next, the ingredients and the process conditions used for the preparation of the TPV will be discussed.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the solubility values for DCP, DTBT, TBCP, TBIB as well as for EPDM and PP.

DETAILED DESCRIPTION OF THE INVENTION A. Polyolefin The polyolefin resin in a TPV is selected from the group comprising one or more polyolefins that originate from a copolymerization of an α-olefin, such as ethylene, propylene, 1-butene and others, as well as also the crystalline polycyclohephines. They also behave like a thermoplastic and have a DSC crystallinity of at least 15%. A preference is present for homo- and copolymers of polyethylene and polypropylene; in the case of copolymers of said polyolefins, the content of ethylene resp. propylene in said copolymer is at least 75% by weight. B. Rubber The TPV rubber used in accordance with the present invention can be any rubber known in the art, provided that the rubber is crosslinkable with peroxide. For a panoramic view of vulcanizable rubbers with peroxides, the reader is referred to the article by Peter R. Diuzneski, in Rubber Chem. Techn., 74, 451 ff, 2001. Suitable preferable rubbers are rubbers selected from the group comprising copolymer rubbers. ethylene / α-olefins (EAM) as well as ethylene / α-olefin / diene terpolymer rubbers (EADM) and acrylonitrile / butadiene rubber (NBR); and its hydrogenated forms HNBR). The rubber can also be a styrene based on thermoplastic elastomers (STPE). A STPE is a block copolymer comprising at least one block substantially based on aromatic polyvinyl monomer), typically a polystyrene block, and at least one elastomeric block substantially based on poly (conjugated dienes), typically a polybutadiene block or polyisoprene or a block of poly (isobutadiene-co-isoprene). The elastomeric block may comprise other copolymerizable monomers, and may be partially or totally hydrogenated. Polystyrene may be based on substituted styrenes, such as α-methylstyrene. The styrene / diene molar ratio varies from 50/50 to 15/85. A preferred form of STPE is at least one of the styrene-butadiene-styrene block copolymers (SBS) and its wholly or partially hydrogenated derivatives (SEBS). Another preferred form of STPE is a tri-block copolymer based on polyethylene and polyisoprene bound to vinyl, and the (partially) hydrogenated derivatives thereof (said copolymers are commercially available from Kraton Polymers). Also polystyrene block copolymers, such as polystyrene-poly (ethylene-co-propylene) -block polystyrene block (SEEPS or SEPS), can be advantageously applied. In the case of an EAM or EADM rubber, the α-olefin in such a rubber is preferably propylene; in which case the rubber is mentioned as EP (D) M. It is also possible to use a mixture of the aforementioned rubbers. C. The TPV The TPV is a family of thermoplastic elastomers comprising a mixture of polyolefin (semi) -crystalline resins and the rubber dispersed in said resin. In general, these mixtures comprise from 15-85 parts by weight of the polyolefin resin and correspondingly from 85-15 parts by weight of the rubber. In the TPV the dispersed rubber is at least partially cured (ie vulcanized). Generally, the rubber in the TPV has a degree of vulcanization such that the amount of rubber extractable from the TPV (based on the total amount of curable rubber) is less than 90%. The test for determining such an extractable amount is generally made with a solvent in which the polyolefin as well as the non-vulcanizable rubber are soluble. A suitable and preferable solvent is boiling xylene.

To enjoy the best vulcanization effects, the TPV is preferably vulcanized to the extent that the amount of extractable rubber is less than 15%, more preferably even less than 5%. D. The peroxide The peroxide to be used to vulcanize the rubber is an organic peroxide that has at least one terminal carbon-carbon double bond in the molecule. Preference is given to such a peroxide, wherein the peroxide is a functional allyl peroxide. Examples of said type of peroxides can be found in EP-A-250, 024. It was found that beneficial effects are obtained on the mechanical properties as well as on the attack by the peroxide on the polyolefin, when the peroxide has a relative solubility (dr of at least 1, where dr is the ratio between the peroxide solubility parameter (dper) and the polyolefin solubility parameter (dpo), both determined at 453 ° K. The solubility parameter d, and especially dper and dpo are calculated using group contribution methods, based on the assumption that the contributions of different functional groups to their thermodynamic properties are additive (see: AFM Braton, "Handbook of Solubility Parameters and Other Cohesion Parameters", CRC Press, Boca Ratón, 1985), using the values of the molar attraction constants given in PA Small, J. Appl. Chem. 3 71 (1953), the solubility parameters of the dif In order to correlate these values to 298 ° K with the temperature under vulcanization conditions, the values of the solubility parameter of the peroxides at 453 ° K are calculated using the following equation: ln dt = ln d298 - 1.25 a (T-298) -1- where a = coefficient of linear thermal expansion of the relevant compound and T = 453 ° K. These are estimated from density measurements up to 353 ° K (see: A. H.

Hogt. Proceedings of the Conference on Advances in Additives and Modifiers for Polymer) and are approximately 10 ~ 3K ~ X The values of the solubility parameter of the polymers (polyolefins and rubber) to 453 ° K are calculated using the following equation: ln dt = In d298-a (T-298) -2- (see S. Krause, in "Polymer Blends" (Eds. DR Paul and S. Newman), Vol. 1, Academic Press., New York, 1978, pp. 15-113); where T = 453 ° K. The coefficient of linear thermal expansion for polypropylene has a value of 6.3 x 10-4K-1; for EPDM said value is 2.3 x 10"4K-1 (see: D. W. Van Krevelen, "Properties of Polymers, their correlation with chemical structure; Their numerical estimation and prediction from group additive contributions", Elsevier, Amsterdam, 1990, p. 189-225; and G. See Strate, "Ethylene-propylene Elastomers" in Encyclopedia of Polymer Science and Engineering, Vol. 6, 6a. Ed., John Wiley & Sons, 1986, p. 522-564). The values of da 453 ° K calculated for DCP, DTBT, TBCP, and TBIB (peroxides used in the Examples and Comparative Experiments, see Table I), are 14.6, 19.6, 13.8 and 12.7 (J / cm3 ) 1 2 respectively, while those of EPDM and PP are 16.6 and 15.1 (J / cm3) 1 2. The variations of these values of d are shown graphically in Figure 1. From these values of d it can be deduced that there is a tendency for TBIB, TBCP and DCP to divide preferably towards the polyolefin phase, as compared to DTBT that will show a preference towards the EPDM phase. It is more preferred that d has a value of at least 1.2. Even more preferable, the dpe is at least equal to the rubber solubility parameter (drUb); in the form of the formula: dper = drub -3- The beneficial effect of the use of a specific peroxide for the present invention is obtained when the peroxide has at least two carbon-carbon double bonds in the molecule. Another preference is in the use of a peroxide that has a triazine nucleus in its molecule.

The amount of peroxide to be used is generally between 0.01 and 15 parts by weight per 100 parts of rubber. Preferably, the quantity is 0.1 - 5.0 parts. After the use of the specific peroxides as indicated above, the crosslinking can be influenced by the use of known co-crosslinking agents, such as those known in the art. Preference is given to those co-agents, whose solubility parameter (dco determined in the same way as all other solubility parameters mentioned above) is at least equal to dpo, and it is still preferred that it be at least equal to the drub. CT with its very high d value, possibly added as a co-agent, preferably ends in the rubber phase, and therefore reinforces the rubber cross-linking effect. With respect to the terminal carbon-carbon double bonds present in the peroxide to be used in the present invention, an additional preference is given to the peroxides, with formula: R'-OO-R ", -4- Where both R ' and R "have these terminal carbon-carbon double bonds. Their use further reduces further the generation of volatile by-products from the peroxides, and therefore further reduces the emission of volatile decomposition products from TPV produced E. The TPV preparation The TPV can be prepared either by mixing the polyolefin with a particulate form of the vulcanized rubber or by a process known as dynamic vulcanization. In the first process, the rubber is vulcanized under conditions known as such with the specific peroxides mentioned above, and thereafter the particle size of the rubber is reduced, as a result of which the particle size is generally between 10 μm, more preferably less than μm. These resulting rubber particles can then be mixed with the polyolefin in a well known manner. It is more preferred that the TPV be prepared under dynamic mixing of the polyolefin, the rubber and the peroxide, as a result of which both the mixing of the rubber in the polyolefin as well as the vulcanization of the rubber take place. The information about the dynamic vulcanization can for example be obtained from the article of Coran &; Patel at Rubber Chem. Techn. 53 141 ff. 1980. The process according to the present invention results in TPVs having improved properties compared to the TPVs known in the art. The unpleasant odor or efflorescence of the surface, which is supposed to be the result of volatile end products of the prior art peroxides, is greatly reduced. Especially when peroxides are used with a dr > 1, the reduction of the mechanical properties of the polyolefin matrix is prevented. The TPV (prepared) according to the present invention can be used successfully in applications where the outstanding properties of the product, especially the properties at high temperatures are advantageous. Reference may be made to automotive parts, especially under the cover (such as clean air ducts, cable coatings, reinforcements and wrappings, housings) machinery, and household equipment. It can also be used in soft-hard combination, such as coextrusion, sequential extrusion and 3D / 2C (ie, three dimensions and two components), as for clean air ducts. The POS can be used especially to prepare an alveolar thermoplastic elastomeric article. To form the cells in the POS, any method known in the art can be used. One or more chemical insufflation agents may be used as well as physical (such as azodicarbonamides, low-boiling hydrocarbons, water, N2, C0, or water-guiding compounds). The blowing agents can be mixed dry or mixed by melting with the TPV (provided that the temperature of the mixture is lower than the activation temperature of the blowing agent) or they can be mixed in gaseous or liquid form in the TPV cast. Preferably, the POS contains the insufflation agent. The amount of insufflating agent is dependent on the type of blowing agent: the maximum insufflation gas is released per unit weight of insufflating agent, the minimum necessary for an accurate result. The person skilled in the art can easily find out the appropriate effective amount of the blowing agent appropriate for the particular type of polymeric foam. In addition to the indicated compounds, the TPV of the present invention may contain additional ingredients, known per se for being used in thermoplastic elastomers, such as fillers, colorants, stabilizing plasticizers (UV), influx enhancers, antioxidants, etc. The invention also concerns an article comprising a POS terminal obtainable with a process of the present invention. Applications in which the POS of the present invention can be used are, for example: belt belts; sealing patches, soft contacts, clamping hooks); sun visors, anti-cent stamps, carpet reinforcements, headliners; seating; flat strips for running; sports pads; wet adaptations, footwear, first aid equipment; reinforcements for fabrics; diapers tapes; different toys; blankets / pads; luggage; floaters, jumpers; auxiliary bands; Earplugs; cups, pads / mattresses; office furniture. In Poster 13 of the International Rubber Conference 2003, held in Nürnberg from June 30 to July 3, 2003, a TPV (process for the preparation of a) TPV was described using an EPDM based on ENB as the rubber having a Mooney viscosity of 52, and a polypropylene with a melt index of 0.3 g / 10 minutes. TBIB as well as DTBT were used as peroxides. The Poster does not recognize or indicate that it is essential that the peroxides have a terminal unsaturation, nor that there is a preference for terminally unsaturated peroxide with a dr > 1. It is also necessary to indicate that better TPVs based on other polyolefins and rubbers can be made. The invention will be elucidated by means of the following Examples and Comparative Experiments, which does not mean that they restrict the invention.

Materials EPDM rubber containing ethylidene norbornene (ENB), including 50% paraffinic oil, was obtained from DSM Elastomers B.V. Netherlands. The EPDM contained 63% by weight of ethylene and 4.5% by weight of ENB; had a viscosity of Mooney, ML (1 + 4) 1 125 ° C of 52. Polypropylene (PP) was obtained from SABIC Polypropylene B.V., The Netherlands. SEBS (Kraton type G1651E) was obtained from Karton Polymers B.V., The Netherlands. The melt influx rate of PP (measured at 503 ° K and 2.16 Kg) was 0.3 / 10 minutes. Two stabilizers, Irganox® 1076 and Irgafox® 168 were obtained from Ciba Geigy. The names and chemical structures of four peroxides investigated are given in Table I as well as their decomposition temperatures corresponding to a half-life of 1 hour which were determined in chlorobenzene solution.

Two types of multifunctional peroxides were synthesized at Azko Nobel Polymer Chemicals, The Netherlands. They combine functionally in a single molecule the peroxide and the co-agent. Two conventional peroxides, DCP and TBCP, were used as reference due to their structural similarity with the multifunctional peroxides. They were also obtained from Akzo Nobel Polymer Chemicals, The Netherlands. 50% triallyl cyanurate (TAC) and 99% methyl styrene (aMeS) were used as references for the co-agents. For DCP and TAC they were used as co-agents because of their structural similarity with DTBT; while for TBCP, a-MeS was applied as a co-agent due to its structural similarity with TBIB. In order to make a slight comparison between the various peroxides care was taken to consider, that with equal amounts of peroxides added per 100 grams of pure EPFM rubber, the amounts of co-agent functionality per 100 grams of pure EPDM differ, depending on the amount of co-agent functionality provided by the peroxide itself. For example, if 15 milliequivalents of peroxide were used, DTBT by its nature having two terminal allylic groups, provided 30 milliequivalents of coagent functionality. This level of 30 co-agent milliquivalents was then taken as a reference and corrections were applied to elaborate it due to the lack of functionality of the co-agent in the other recipes by addition of either TAC or a-MeS, as shown in Table II. Preparation of PP / EPDM TPVs The PP / EPDM TPV compositions employed are given in Tables III and IV. The experimental variables were the concentrations of peroxide and co-agent (Table III) and the proportion of the PP / EPDM mixture: (Table IV). All TPVs were prepared by mixing in a batch process in a Brabender Plasti-Corder PL-2000, which has a mixing chamber volume of 50 ce. The batch size was 36 grams. The temperature of the mixers conserved at 453 -463 ° K. A constant rotor speed (cam type) of 80 rpm was applied. First, PP, stabilizers (Irganox 1076 and Irgafox 168) and EPDM rubber were mechanically mixed. After 4 minutes of mixing, the coagent, either TAC or α-MeS, was added, followed by the peroxide. Mixing was continued for another five minutes to complete the dynamic vulcanization process. Immediately after mixing, the composition was removed from the mixer and while it was still molten it was passed once through a cold two-roll mill to achieve a sheet about 2 mm thick. The sheet was cut and compressed (2 mm thick) in a compression molding machine (laboratory press WLP 1600/5 '4/3 Wickerta 473 K, 4 minutes and 12.5 MPa pressure). An aluminum sheet was placed between the molded sheet and the press plates. The sheet was then cooled to room temperature under pressure. These specimens were cut with the die from the compression molded sheet and were used for testing after 24 hours of storage at room temperature. Test Procedures Traction tests were carried out on the TPVs according to ISO 37 on specimens formed with ends of greater section than the central part (Type 2) using a Zwick Z020 tensile testing machine at a shear rate of 500 mm / min. The Young's modulus was determined from the initial slope of the strain-strain curve between the deformation of 0.1% and 0.25% at a speed of 50 mm / min. The hardness of the samples was measured by means of a Zwick hardness meter (Limit Type A, ISO R868). The total crosslink density of the EPDM phase in the presence of PP was determined based on the equilibrium-foaming solvent (cyclohexane at 296 K). A 2 mm thick sample was immersed in cyclohexane. After 24 hours the cyclohexane was renewed to remove the extracted oil and the organic stabilizer. After another 24 hours, the swollen sample was weighed, dried and weighed again. From the degree of swelling the total crosslink density was calculated which was expressed by (v + PP). Examples IV and Comparative Experiments AF Influence of different types and concentrations of peroxides on the physical properties of TPVs at a fixed PP / EPDM mixing ratio of 50 phr of PP In Table III the mechanical properties of the TPVs of PP / EPDM cured with various crosslinking agents at their different concentrations. For DTBT, there is a clear tendency to increase the tensile stress with more added crosslinking agent. An increase in hardness values is indicated in all cases with increasing cross-linking agent dosage (Table III). The average values of the hardness varied between 50-70 Limit A. The DTBT of the crosslinking system, without extra co-agents added, gave higher values than the others. Examples VII-XVI and Comparative Experiments G-R Influence of different types of peroxides at fixed concentrations on the physical properties of TPVs with various proportions of PP / EPDM mixtures. In Table IV the mechanical properties of PP / EPDM TPVs cured with various cross-linking agents and with various mixing ratios are given. The properties corresponding to 50 phr were already given in the Table III. The data show that the tensile stress increases with the increase in the amount of PP. At 125 phr of PP, the multifunctional peroxide DTBT exhibits the maximum tensile stress.

The results of elongation at rupture showed very different results for the four peroxides investigated. Paw DTBT was not observed any significant dependence on the elongation at break for the various contents of PP. Young's modulus increases with the increase in the amount of PP at 125 phr of PP, DTBT exhibited the maximum value of Young's Modulus M300 also increases with the increase in the amount of PP. There was an increase in the hardness values with the increase in PP content. Small total differences were observed among the various peroxides. Examples XVII-VIII and Comparative Experiments S-T. Examples III and VI were repeated, and Comparative Experiments C and F. EPDM was replaced by SEBS. In order to be comparable in the recipe, 100 parts of oil were added, when the EPD was extended in oil. The results are given in Table V. Evasion of Byproducts with Unpleasant Odor From Table VI it can be derived that DCP first generates cumyloxy radicals, which are further decomposed into acetophenone, which has a typical sweet odor and highly reactive methyl radicals. Similarly, TBCP forms large amounts of acetophenone, when this compound is medium resembles DCP. From the decomposition products of TBIB, it can be deduced that the amount of aromatic alcohol and the aromatic ketone are at the lower limit of detection (< 0.01 mol / mol of decomposed peroxide); no additional footprint of other products - of decomposition could be determined. This implies that most of the aromatic decomposition products reacted with the substrate by the formation of adducts. As DTBT contains the same basic butyl peroxide unit as TBIB, it can be anticipated that its primary decomposition products will be similar. This also explains why the decomposition products obtained from both multifunctional peroxides do not provide any unpleasant odor, unlike DCP. As a result, the use of multifunctional peroxides, such as DTBT and TBIB, which have both peroxide and co-agent functionalities in a single molecule, provide TPV properties, which are very comparable with peroxides aided by the commonly used co-agent. . With DCP aided by the co-agent TAC taken as reference for the total combination of physical properties in PP / rubber TPVs, particularly DTBT gives the best result of the two. DTBT has a solubility parameter on the upper side of the spectrum, which directs this peroxide / co-agent combination preferably in the rubber phase during mixing. The functionality of the co-agent of this compound improves the effect of the crosslinker, in order to be comparable with DCP. DTBT showed a decomposition temperature in relation to t? / 2 = 1 hour close to DCP, which results in a vulcanization rate, which is very comparable. Multifunctional peroxides can provide byproducts after decomposition but without unpleasant odor unlike DCP.

TABLE 1 CHEMICAL / COMMERCIAL NAMES, TEMPERATURE CORRECTED TO THE AVERAGE LIFETIME OF 1 HOUR, AND STRUCTURES OF PEROXIDES STUDIED Chemical Name / Commercial T (K) Chemical Structure for T y2 = 1 hour 1 - . 1 - (2-tert-ButylperoxyisopropyI) - 411 3-isopropenyl benzene (TBIB (71%): multifunctional 2,4-Diallyloxy-6-tert-butylperoxy-405-1,3,5-triazine (DTBT) (95%): multifunctional Dicumyl peroxide (DCP) (Perkadox * T) (50%) Tri-butyl cumyl peroxide 404 (TBCP) (Trigonox®T) (50%) Registered trademark of Akzo Nobel Chemicals B.V.

Table II. CORRECTION FOR FUNCTIONALITY OF CO-AGENT (Or KJx KJ? Table III. POS (phr) compositions and corresponding properties. Variation of peroxide and co-agent concentrations # Includes 50% paraffinic oils * Numbers in brackets represent milli-equivalents of peroxides and co-agents per 100 parts of pure EPDM rubber t to i or Ul Ul Table V. POS compositions based on SEBS TABLE VI. RELATIVE AMOUNTS OF DECOMPOSITION PRODUCTS FROM VARIOUS PEROXIDES Temperature Name Relative Quantity Products Experimental peroxide (K) - decomposition (moles / mole of peroxide) DCP 433 Methane 0.91 Acetophenone 0.91 2-phenylpropanol-2 1.06 A-methyl esters 0.01 Water 0.01 TBCP 428 Methane 0.57 Acetone 0.13 Ter-butanol 0.79 Acetophenone 0.44 2-Phenylpropanol-2 0.53 TBIB 428 Methane 0.63 Acetone 0.11 Ter-butanol 0.89 1- (2-isopropanol) -3-lsopropenol Benzene < 0.01 1-acetyl-3-isopropenyl benzene < 0.Q1 Water 0.04 DTBP 425 Methane 0.24 Acetone 0.36 Ter-butanol 1.63 Pentadecane dimer 0.40

Claims (16)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty, and therefore the content of the following is claimed as property: CLAIMS 1. Process for the preparation of a thermoplastic elastomeric vulcanizate (TPV) characterized in that it comprises a mixture of a polyolefin and a vulcanized rubber, in which the vulcanization of the rubber is carried out at elevated temperature under the influence of a peroxide, wherein the peroxide is a peroxide organic that has at least one terminal carbon-carbon double bond in the molecule. 2. Process according to claim 1, characterized in that the peroxide is a functional allyl peroxide. Process according to any of claims 1-2, characterized in that the peroxide has a relative solubility of at least 1, where dr is the ratio between the peroxide solubility parameter (dper) and the solubility parameter of the polyolefin (dpo), both determined at 453 ° K. 4. Process according to claim 3, characterized in that dr has a value of at least 1.
2. 2. Process according to any of claims 3-4, characterized in that the dper is at least equal to the rubber solubility parameter (drUb). 6. Process according to any of claims 1-5, characterized in that the TPV is prepared via dynamic vulcanization. Process according to any of claims 1-6, characterized in that the polyolefin is selected from the group comprising polyethylene and polypropylene. Process according to any of claims 1-7, characterized in that the rubber is selected from the group comprising EA (D) M, (hydrogenated), styrenic block copolymers, and (H) NBR rubber. 9. Process according to any of claims 1-8, characterized in that the peroxide has at least two carbon-carbon double bonds in the molecule. 10. Process according to any of claims 1-9, characterized in that the peroxide has a triazine nucleus in its molecule. 11. Process according to any of claims 1-10, characterized in that the TPV is prepared by dynamically vulcanizing a mixture of polypropylene, EPM or EPDM, and a peroxide having a triazine nucleus in its molecule. Process according to any of claims 1-11, characterized in that the density of crosslinking of the rubber in the TPV, determined as a boiling xylene gel content, is at least 90%. 13. Process according to claim 12, characterized in that the crosslink density is at least 95%. 14. Process according to any of claims 1-13, characterized in that the amount of peroxide is from 0.5 to 5.0 parts by weight per 100 parts by weight of rubber. 15. Thermoplastic vulcanizate (TPV), obtainable by means of a process according to any of claims 1-14. 16. Article, characterized in that it comprises a POS in accordance with claim 15, or a POS-prepared with a process according to any of claims 1-14.