A thermoplastic elastomer material comprising a dispersion of pre-crosslinked rubber particles and its manufacturing process

Abstract

The present invention relates to a thermoplastic elastomeric material comprising: a thermoplastic elastomeric matrix, and previously crosslinked rubber particles dispersed within said matrix. The thermoplastic elastomeric material is characterized in that: said crosslinked rubber particles represent 50 to 90% by weight of the total weight of said thermoplastic elastomeric material, and said thermoplastic matrix represents 10 to 50% by weight of the total weight of said thermoplastic elastomeric material. The thermoplastic elastomeric matrix comprises a mixture of one or more hard and / or soft grafted thermoplastic polymers, one or more hard and / or soft non-grafted thermoplastic polymers, and a plasticizer. The hard and / or soft grafted thermoplastic polymers represent at most 9% by weight of the total weight of said thermoplastic elastomeric material. The invention also relates to a process for obtaining such a material.

Description

Title of the invention: Thermoplastic elastomeric material comprising a dispersion of pre-crosslinked rubber particles and its manufacturing process. Technical field of the invention

[0001] The present invention relates to a thermoplastic elastomer material with improved mechanical properties, as well as its manufacturing process, said thermoplastic elastomer material comprising a thermoplastic elastomer matrix in which previously crosslinked rubber particles are dispersed. Technical background

[0002] Thermoplastic elastomers (usually referred to by the acronym TPE) have recently become economically dominant because they combine good mechanical properties and remarkable elastic properties.

[0003] Among TPEs, we know in particular vulcanized thermoplastics (usually designated by the acronym TPV) which contain a dynamically crosslinked elastomer phase dispersed in a thermoplastic matrix phase.

[0004] Such materials do not allow the use of pre-crosslinked elastomers, particularly those derived from recycling. To solve this problem and allow the integration of crosslinked rubber into the thermoplastic matrix, those skilled in the art have developed TPE compounds made from a hard thermoplastic material (for example, polypropylene), combined with pre-crosslinked elastomers, particularly those derived from recycling.

[0005] To allow a finely dispersed distribution of previously crosslinked Telatomer in the thermoplastic matrix, it is known to those skilled in the art to use various reaction intermediates that promote interactions between the thermoplastic matrix and Telatomer.

[0006] Thus, the German utility model DE 295 157 21 U1 describes a thermoplastic material modified by ground rubber. More specifically, it describes the insertion of ground elastomer, such as recycled rubber, into a thermoplastic elastomer (TPE) matrix. The matrix can be composed of polypropylene blended with an ethylene-propylene-diene rubber monomer (usually designated by the acronym EPDM). To improve the bond between the matrix polymer and the elastomer, radical generators (e.g., peroxides), acids (e.g., maleic anhydride), or functionalized copolymers can be used.

[0007] Furthermore, European patent application EP 0 649 871 A2 discloses a thermoplastic composition comprising vulcanized rubber and polyolefin resin, this composition being improved by the incorporation of functionalized polyolefin resin. In the process for obtaining the composition, the rubber, the polyolefin resin, and the functionalized polyolefin resin are mixed, either in a single step or in two successive steps, with a first step consisting of mixing the rubber with the polyolefin resin, followed by a further step consisting of mixing the mixture obtained in the first step with the functionalized polyolefin resin.

[0008] However, the process taught by document EP 0 649 871 A2 has the disadvantage of requiring a high quantity of functionalized copolymers (at least 10% by weight, in particular around 25% by weight), which are generally very expensive, whereas the elastomer powder is recycled rubber powder, which is inexpensive.

[0009] The present invention aims in particular to overcome these drawbacks of the prior art.

[0010] In particular, the invention aims in particular to provide a thermoplastic elastomer material exhibiting good mechanical characteristics.

[0011] Another objective of the invention, according to some of its embodiments, is to provide such a material that can be manufactured at a reduced cost.

[0012] A particular objective of the invention, according to some of its embodiments, is to provide such a material incorporating a large quantity of previously crosslinked rubber particles. Summary of the invention

[0013] One of the objects of the present invention is therefore a thermoplastic elastomeric material comprising: - a thermoplastic elastomer matrix, - previously cross-linked rubber particles dispersed in said matrix,

[0014] said thermoplastic elastomer material being characterized in that: - said cross-linked rubber particles represent 50 to 90% by weight of the total weight of said thermoplastic elastomer material, and - said thermoplastic matrix represents 10 to 50% by weight of the total weight of said thermoplastic elastomer material, said thermoplastic elastomer matrix comprising a mixture of one or more hard and / or soft grafted thermoplastic polymers, one or more hard and / or soft non-grafted thermoplastic polymers, and a plasticizer, and said hard and / or soft grafted thermoplastic polymers representing at most 9% by weight of the total weight of said thermoplastic elastomer material. Thermoplastic elastomer matrix

[0015] By hard polymers (whether grafted or not), we mean, for the purposes of the present invention, polymers having a hardness greater than 95 Shore A.

[0016] Conversely, by soft polymers (whether grafted or not), we mean, in the context of the present invention, polymers having a hardness of less than 95 Shore A.

[0017] Examples of hard thermoplastic polymers, whether or not grafted, include polymers selected from the group comprising polyolefins (preferably polypropylene, usually designated by the acronym PP) and polystyrene (usually designated by the acronym PS), and examples of soft thermoplastic polymers, whether or not grafted, include thermoplastic elastomeric copolymers.

[0018] Preferably, the soft thermoplastic polymers, whether or not grafted, may be chosen from the group comprising styrene block copolymers, vulcanized thermoplastics (usually referred to by the acronym TPV) of the type dynamically vulcanized ethylene propylene diene monomer (usually referred to by the acronym EPDM) in a polypropylene matrix (PP / EPDM), ethylene vinyl acetate (usually referred to by the acronym EVA) and thermoplastic polyurethanes (usually referred to by the acronym TPU).

[0019] By way of styrenic block copolymers usable as soft thermoplastic polymers, within the scope of the present invention, we may in particular mention the styrene-butadiene-styrene block copolymer (usually designated by the acronym SBS), the styrene-ethylene-butylene-styrene or polystyrene polyethylene-butylene block copolymer (usually designated by the acronym SEBS), the styrene-ethylene-propylene-styrene block copolymer (usually designated by the acronym SEPS), the styrene-ethylene-ethylene-propylene-styrene block copolymer (usually designated by the acronym SEEPS), the polystyrene-isobutylene-block-styrene block copolymer (usually designated by the acronym SIBS), the styrene-isoprene-styrene block copolymer, etc. The SEBS system should preferably be used.

[0020] As plasticizers that can be used in the context of the present invention, naphthenic or paraffinic mineral oils, vegetable oils or esters such as phthalates, adipates or sebacates may be mentioned in particular.

[0021] Advantageously, hard and soft grafted thermoplastic polymers can be grafted either with maleic acid or with methyl methacrylate.

[0022] Preferably, the hard and soft grafted thermoplastic polymers are grafted with maleic acid. In this particular preferred case (grafting of polymers thermoplastics by maleic acid), a thermoplastic material according to the invention may have the following composition: - 0-20% by weight of polypropylene (usually referred to by the acronym PP) or polystyrene (usually referred to by the acronym PS) not grafted relative to the total weight of the thermoplastic elastomer material; - 1-10% by weight of polystyrene polyethylene-butylene (usually designated (by the acronym SEBS) ungrafted and / or 5-25% by weight of TPV PP / EPDM relative to the total weight of the thermoplastic elastomer material, - 0-15% by weight of grafted PP relative to the total weight of the material thermoplastic elastomer; - 0-15% by weight of grafted SEBS relative to the total weight of the material thermoplastic elastomer, - 1-20% by weight of plasticizer relative to the total weight of the material thermoplastic elastomer. Crosslinked rubber particles

[0023] By pre-crosslinked rubber particles, we mean, in the context of the present invention, rubber particles that are not dynamically crosslinked during the synthesis of the thermoplastic material according to the invention.

[0024] It is possible, with a percentage by weight of previously crosslinked rubber particles as high as 50 to 90% by weight of the total weight of said thermoplastic elastomer material, to obtain a thermoplastic elastomer material exhibiting good elastic characteristics and in particular an elongation at break greater than 100%.

[0025] Advantageously, the crosslinked rubber particles can represent 65 to 85% by weight of the total weight of the thermoplastic elastomer material, and said thermoplastic matrix represents 15 to 35% by weight of said thermoplastic elastomer material.

[0026] Advantageously, the crosslinked rubber particles come from the recycling of industrial waste or finished objects after use.

[0027] Examples of finished objects after use that can be used to recycle cross-linked rubber include outsoles of shoes or used tires.

[0028] In order to reduce the quantity of costly functionalized compounds while maintaining control over the final properties of the TPE material, the Applicant has developed a process to optimize their efficiency and thus reduce their quantity in the final thermoplastic elastomer material. This is achieved through a two-step process in which a grafted polymer is mixed with the elastomer powder in the first step, so that they adhere to the surface of the particles. elastomer powder; then, these particles in the modified surface state are mixed, in a second step, with an ungrafted polymer.

[0029] Another object of the present invention is therefore a method for manufacturing a thermoplastic material according to the invention comprising the following steps: - a first step A) of mixing crosslinked rubber particles and one or more hard and / or soft grafted thermoplastic polymers, to obtain a mixture of crosslinked rubber particles having a modified surface state at the end of step A; - a second step B) of mixing said crosslinked rubber particles having a modified surface state obtained in step A with a mixture of one or more hard and / or soft non-grafted thermoplastic polymers, and a plasticizer.

[0030] Advantageously, step A can be carried out by mixing crosslinked rubber particles with grafted PP and optionally also with grafted polyethylene-butylene polystyrene, while step B can be carried out by mixing said crosslinked rubber particles obtained in step A having a modified surface state, with ungrafted PP or PS on the one hand, and ungrafted SEBS or a PP / EPDM type TPV on the other hand.

[0031] Advantageously, depending on whether the aim is to harden or further soften the thermoplastic elastomer material, either unbonded PP or a plasticizer can be added during step B. The degree of hardness is thus chosen independently of the properties of the elastomer powder. This adjustment of the composition's hardness allows the material to be advantageously adapted to its final use. Detailed description of the invention

[0032] Other features and advantages of the invention may also become apparent to a person skilled in the art upon reading the examples below, given by way of illustration and not limitation. EXAMPLES Products and raw materials

[0033] Crosslinked rubber particles: - tire powder marketed by the company Rubber Jet Valley under the trade name RJP200; - tire powder marketed by the company Tyre Recycling Solutions under the trade name CW50; - tire powder marketed by the company Yildiz Endustri under the trade name "50-mesh tire powder", hereinafter referred to as YE50; - tire powder marketed by the company GMN under the trade name B11; - tire powder marketed by the company Genan under the trade name "Superfine powder", hereinafter referred to as GA30; - shoe sole powder marketed by The 8 Impact company, hereinafter referred to as RTP35.

[0034] Non-grafted thermoplastic polymers: in the form of non-grafted thermoplastic elastomer TPE compounds comprising non-grafted polypropylene PP and SEBS (in this case the compound is a TPS compound) or PP / EPDM (in this case the compound is a TPV compound) and paraffinic oil;

[0035] TPS-type compounds are marketed under the following trade names: - SD300-45A by the company Ensoft, whose share of SEBS is noted below SEBS 1; - CHS90-0000-040 by Cabopol, whose share of SEBS is noted below- after SEBS 2,

[0036] TPV type compounds are marketed under the trade name 121.58 by the company Celanese.

[0037] Grafted thermoplastic polymers: - PP grafted marketed by SK Functional Polymers under the trade name OREVAC CA 100, hereinafter referred to as F; - Grafted PP marketed by the company Tisan under the trade name OLEBOND 7401CH.

[0038] Plasticizer: Paraffin oil contained in ungrafted TPE compounds, and possibly supplemented by oil marketed by the company DirectLub under the trade name Mouvement 100. CHARACTERIZATION TESTS

[0039] Hardness measurement:

[0040] Hardness measurement is performed using a method employing a durometer that controls the penetration of a frustoconical punch (with a sharp point), actuated by a spring or a weight, into the surface of a sample of the thermoplastic material whose hardness is being measured. The punch and the spring, which cause the punch's displacement, are part of the durometer, which also includes a device consisting of a graduated dial and a movable pointer opposite this dial for quick and easy reading of the punch penetration into the rubber sample, translated into degrees of hardness. In the case of the present invention, the hardness measurement is performed in accordance with ISO 868, which provides hardness values ​​expressed in Shore A. MATERIALS USED FOR CHARACTERIZATION

[0041] Measurement of breaking strength, measurement of elongation at break

[0042] The elongation at break eb of a polymer material is the last elongation value recorded before the stress fell to less than 10% (or equal to 10%) of the strength.

[0043] The tensile strength and elongation at break are measured by applying ISO 37.

[0044] DRC measurement

[0045] Compression set (CS), or compression set, is measured by applying the NF ISO 815 standard. Its purpose is to determine the compression set of vulcanized or thermoplastic rubbers. In other words, it assesses the ability of thermoplastic materials to retain their elastic properties after prolonged compression at constant deformation at specific temperatures (23°C and 70°C in this case). This test is based on the principle that when a rubber, or more generally a thermoplastic material, is held under pressure, physical or chemical changes can occur: once the material is released, it will not return to its original dimensions. This results in a short-term compression set (usually 24 hours at high temperature).

[0046] This is a test which lasts 24 hours, carried out at room temperature or at high temperature (in this case at 70°C).

[0047] EXAMPLE 1: Preparation of thermoplastic elastomeric materials according to a first embodiment according to the invention (based on SEBS 1 and grafted PP F)

[0048] Different compositions of plastic materials are prepared, the compositions of which are given in Table 1 below.

[0049] [Tables 1] Test of Crosslinked Rubber Powder Final Composition of the Thermoplastic Elastomer Matrix Compounds Added During Step B Type Quantity (%) Type Quantity (%) R64 RJP200 72 PP Grafted PP F SEBS 1 Oil 8.4 8 4.6 7 TPE-SD45 PP R71 CW50 72 PP Grafted PP F SEBS 1 8.4 8 4.6 TPE-SD45 PP Oil 7 R74 CW50 72 PP PP grafted F SEBS 1 Oil 3.4 8 6.6 10 TPE-SD45 R76 CW50 72 PP PP grafted F SEBS 1 Oil 3.7 6 7.3 11 TPE-SD45 R77 CW50 72 PP PP grafted F SEBS 1 Oil 2 8 4 14 TPE-SD45 Oil R78 CW50 73.8 PP PP grafted F SEBS 1 Oil 3.4 6.2 6.6 10 TPE-SD45 R84 CW50 76.5 PP PP grafted F SEBS 1 Oil 2.5 8.5 5 7.5 TPE-SD45 R85 CW50 78 PP PP grafted F SEBS 1 Oil 2.7 6.2 5.2 7.9 TPE-SD45 R86 CW50 78 PP Grafted PP F SEBS 1 Oil 2.7 8.6 5.2 7.9 TPE-SD45 R91 YE50 72 PP Grafted PP F SEBS 1 Oil 3.4 8 6.6 10 TPE-SD45

[0050] The preparation of these materials is carried out in the following manner: - A) mixing of crosslinked rubber particles with grafted polypropylene; - B) mixing of said rubber particles obtained at the end of step A with a TPS compound (marketed under the name SD300-45A).

[0051] EXAMPLE 2: Preparation of thermoplastic elastomeric materials according to a second embodiment according to the invention (based on SEBS2 of grafted PP T)

[0052] Different compositions of plastic materials are prepared, the compositions of which are given in Table 2 below.

[0053] [Tables2] Test Crosslinked Rubber Powder Final Composition of the Thermoplastic Elastomer Matrix Compounds Added During Step B Type Quantity (%) Type Quantity (%) R95 CW50 72 PP Grafted PP T SEBS 2 Oil 3.4 8 6.6 10 TPE-C50 R96 YE50 72 PP Grafted PP T SEBS 2 Oil 3.4 8 6.6 10 TPE-C50 R98 RTP35 (shoe soles) 72 PP Grafted PP T SEBS 2 Oil 3.4 8 6.6 10 TPE-C50 R100 Bll 72 PP Grafted PP T SEBS 2 Oil 3.4 8 6.6 10 TPE-C50 R105 CW50 72 PP Grafted PP T SEBS 2 Oil 3.4 8 6.6 11 TPE-C40 R126 CW50 72 PP PP grafted T 8.1 8 TPE-C40 PP SEBS 2 Oil 4.2 7.7 R128 CW50 65.6 PP Grafted PP T SEBS 2 Oil 3 7.2 6 18.2 TPE-C40 Oil

[0054] The preparation of these materials is carried out in the same way as in example 1, but replacing: - in step A, the grafted PP F with a grafted PP T, and - in step B, the TPS compound marketed under the name SD300- 45A by the TPS compound marketed under the name CHS90-000-040.

[0055] EXAMPLE 3: Preparation of thermoplastic elastomeric materials according to a third embodiment according to the invention (based on dynamically crosslinked PP / EPDM and T-grafted PP)

[0056] A composition of plastic material is prepared, the composition of which is given in Table 3 below.

[0057] [Tables3] Test of Crosslinked Rubber Powder Final Composition of the Thermoplastic Elastomer Matrix Compounds Added During Step B Type Quantity (%) Type Quantity (%) R103 CW50 72 PP Grafted PP Dynamically Crosslinked EPDM Oil 3.4 8 8.3 8.3 TPV-60

[0058] The preparation of these materials is carried out in the same way as in example 1, but replacing: - in step A, the grafted PP F with a grafted PP T, and - in step B, the TPS compound by the TPV compound 121.58.

[0059] EXAMPLE 4: Preparation of thermoplastic elastomeric materials based on the prior art: absence of step A of mixing the rubber powder with grafted PP (test R 7 3) or absence of addition of compound T PE (test R129)

[0060] A composition of plastic material is prepared, the composition of which is given in Table 4 below.

[0061] [Tables4] Test of Crosslinked Rubber Powder Final Composition of the Thermoplastic Elastomer Matrix Compounds Added During Step B Type Quantity (%) Type Quantity (%) R73 CW50 72 PP Grafted PP F SEBS Oil 16.4 0 4.6 7 TPE-SD45 PP R129 GA30 81.1 PP Grafted PP T SEBS 2 Oil 10 8.9 0 0 PP

[0062] For the preparation of the material for test R73, the crosslinked rubber particles are mixed directly with the compound and ungrafted PP.

[0063] The preparation of the material for test R129 is carried out in the same manner as in example 1, but replacing: - in step A, the grafted PP F with a grafted PP T, and - In step B, the particles obtained in step A are mixed with only PP: there is no addition of TPE compound. Results of characterization tests

[0064] The various thermoplastic materials produced in Examples 1 to 4 have all been mechanically characterized and the results of these tests are gathered in Tables 5 to 8 below.

[0065] Characterization of thermoplastic materials of example 1

[0066] [Tables5] Tests: Crosslinked Rubber Powder Matrix Opening Hardness at Break DRC 23°C / 24h DRC 70°C / 24h Type Qty (%) Type ShA MPa % % % R64 RJP200 72 TPE-SD45 PP 75 5.78 160 R71 CW50 72 TPE-SD45 PP 79 8.65 210 R74 CW50 72 TPE-SD45 70 5.93 235 22 38 R76 CW50 72 TPE-SD45 67 4.72 226 22 R77 CW50 72 TPE-SD45 55 4.08 209 21 Oil R78 CW50 73.8 TPE-SD45 65 5.14 224 21 R84 CW50 76.5 TPE-SD45 68 5.69 197 22 R85 CW50 78 TPE-SD45 66 5.6 198 22 R86 CW50 78 TPE-SD45 69 6.62 226 23 R91 YE50 72 TPE-SD45 72 5.05 181 30

[0067] Characterization of thermoplastic materials of example 2

[0068] [Tableauxô] Tests Crosslinked Rubber Powder Matrix Hardness of rupture DRC 23°C / 24h DRC 23°C / 24h Type Qty (%) ShA MPa % MPa % % R95 CW50 72 TPE-C50 ShA 6.82 >244 23 R96 YE50 72 TPE-C50 74 6.77 198 26 R98 RTP35 (shoe soles) 72 TPE-C50 78 6.49 263 31 R100 Bll 72 TPE-C50 68 5.48 171 28 R105 CW50 72 TPE-C40 67 6.94 271 22 R126 CW50 72 TPE-C40 PP 77 7.84 236 29 R128 CW50 65.6 TPE-C40 Oil 51 3.63 270 19 71

[0069] Characterization of thermoplastic materials of example 3

[0070] [Tables7] Tests Crosslinked Rubber Powder Matrix Hardness at break DRC 23 °C / 24h DRC 70 °C / 24h Type Qty (%) ShA MPa % % % R103 CW50 72 TPV-60 75 6.55 197 25

[0071] Characterization of thermoplastic materials of example 4

[0072] [Tables8] Tests Crosslinked Rubber Powder Matrix Hardness at Break DRC 23 °C / 24h DRC 70 °C / 24h Type Qty (%) ShA MPa % % % R73 CW50 72 TPE-SD45 PP 83 7.71 121 28 R129 GA30 81.1 PP 87 9.16 114

[0073] In general, results tables 6 to 8 show that: - the absence of TPE compound or step A (absence of mixing with a grafted PP) leads to a very hard material, with very low elongation at break and high breaking strength: R129 or R73 tests of example 4; - The addition of PP during step B hardens the thermoplastic material formed, increases its tensile strength, decreases its elongation at break and increases the DRC: • comparison of tests R73 and R74 in particular (example 1); • Comparison of R95 and R126 tests (example 2) - the addition of oil during step B softens the thermoplastic material formed, reduces its resistance to break, decreases the DRC, but has little impact on its elongation at break: comparison of tests R75 and R77; - ground-up shoe soles also give very good results (test R98 of example 3).

Claims

Demands

1. A thermoplastic elastomeric material comprising: - a thermoplastic elastomeric matrix, - previously crosslinked rubber particles dispersed in said matrix, said thermoplastic elastomeric material being characterized in that: - said crosslinked rubber particles represent 50 to 90% by weight of the total weight of said thermoplastic elastomeric material, and - said thermoplastic matrix represents 10 to 50% by weight of the total weight of said thermoplastic elastomeric material, said thermoplastic elastomeric matrix comprising a mixture of one or more hard and / or soft grafted thermoplastic polymers, one or more hard and / or soft non-grafted thermoplastic polymers, and a plasticizer, and said hard and / or soft grafted thermoplastic polymers representing at most 9% by weight of the total weight of said thermoplastic elastomeric material.

2. Thermoplastic elastomer material according to claim 1, wherein said crosslinked rubber particles represent 65 to 85% by weight of the total weight of said thermoplastic elastomer material, and said thermoplastic matrix represents 15 to 35% by weight of the total weight of said thermoplastic elastomer material.

3. Thermoplastic elastomeric material according to any one of claims 1 and 2, wherein the crosslinked rubber particles are derived from the recycling of industrial waste or finished after-use articles, preferably from the outer soles of shoes or used tires.

4. Thermoplastic elastomeric material according to any one of claims 1 to 3, wherein said hard thermoplastic polymers, whether grafted or not, are selected from the group comprising polyolefins and polystyrene, and said soft thermoplastic polymers, whether grafted or not, are selected from the group comprising thermoplastic elastomeric copolymers.

5. A thermoplastic elastomer material according to claim 4, wherein said soft thermoplastic polymers, whether grafted or not, are selected from the group comprising block copolymers styrenes, vulcanized thermoplastics (usually referred to by the acronym TPV) of the ethylene propylene diene monomer type dynamically vulcanized (usually referred to by the acronym EPDM) in a polypropylene matrix (PP / EPDM), ethylene vinyl acetate (usually referred to by the acronym EVA) and thermoplastic polyurethanes (usually referred to by the acronym TPU).

6. Thermoplastic elastomeric material according to any one of claims 1 to 5, wherein said hard and soft grafted thermoplastic polymers are grafted with maleic acid or methyl methacrylate.

7. Thermoplastic elastomer material according to claim 6, wherein said hard and soft grafted thermoplastic polymers are grafted with maleic acid.

8. Thermoplastic elastomeric material according to claim 7, comprising: - 0-20% by weight of ungrafted polypropylene or polystyrene, relative to the total weight of the thermoplastic elastomeric material; - 1-10% by weight of ungrafted polyethylene-butylene polystyrene and / or 5-25% by weight of TPV PP / EPDM, relative to the total weight of the thermoplastic elastomeric material, - 0-9% by weight of grafted polypropylene, relative to the total weight of the thermoplastic elastomeric material; - 0-9% by weight of grafted polyethylene-butylene polystyrene, relative to the total weight of the thermoplastic elastomeric material, - 1-20% by weight of plasticizer, relative to the total weight of the thermoplastic elastomeric material.

9. A method for manufacturing a thermoplastic material as defined according to any one of claims 1 to 8, comprising the following steps: - a first step A of mixing crosslinked rubber particles and one or more hard and / or soft grafted thermoplastic polymers, to obtain a mixture of crosslinked rubber particles having a modified surface state; - a second step B of mixing said crosslinked rubber particles having a modified surface state obtained at the end of step A with a mixture of one or more hard and / or soft non-grafted thermoplastic polymers, and a plasticizer.

10. A method for manufacturing a thermoplastic material according to claim 9, wherein: - step A is carried out by mixing crosslinked rubber particles with grafted polypropylene and optionally also with grafted polyethylene-butylene polystyrene; and - step B is carried out by mixing said crosslinked rubber particles obtained in step A having a modified surface state, with ungrafted polypropylene or polystyrene on the one hand, and ungrafted polyethylene-butylene polystyrene or TPV PP / EPDM on the other hand.