Vulcanizing agent for bitumen

Abstract

Vulcanizing agent for vulcanizing bitumen, said vulcanizing agent being in tablet form and comprising a sulphurated agent and a binder, said sulphurated agent comprising zinc dibenzyldithiocarbamate (ZBEC).

Description

[0001] Vulcanizing agent for bitumen

[0002] The present invention relates to a vulcanizing agent for bitumen which, when mixed with bitumen and an elastomer, allows the preparation of crosslinked bitumen / polymer compositions. The invention also relates to a process for preparing such a vulcanizing agent. The invention further relates to a process for preparing a crosslinked bitumen / polymer composition using such a vulcanizing agent, as well as the resulting crosslinked bitumen / polymer composition. The invention relates to applications, in particular for roads, of crosslinked bitumen / polymer compositions according to the invention.

[0003] It is known, particularly in the context of bituminous road surface compositions, to add elastomeric polymers to the bitumen. The introduction of an elastomer improves the elastic properties of the bitumen by allowing it to deform under pressure (for example when a vehicle drives over it) and then return to its initial state. These elastic properties thus increase the lifespan of the road surface. It is also known to strengthen the elastic properties of these bitumen / polymer compositions by causing them to crosslink, particularly by adding sulfur or sulfur-containing compounds. This crosslinking step is conventionally referred to as vulcanization.The formation of these crosslinked (or vulcanized) bitumen / polymer compositions is generally carried out in two stages: the elastomer is added to the bitumen and fully dispersed, and then the vulcanizing agent is added to initiate crosslinking of the system. A number of published patent applications describe such processes, including WO 98 / 47966, WO 92 / 11321, WO 90 / 02776, WO 93 / 18092 and WO 96 / 15193.

[0004] Such a process is disclosed in particular in published European patent EP 424420. This document discloses the formation of a bitumen / polymer composition in two stages. An elastomer-type polymer (SBS) is dispersed in the bitumen at a temperature of approximately 140-180°C. Once the SBS is fully dispersed in the bitumen, vulcanizing agents are added, including sulfur, a sulfur donor and other additives. The mixture is then stirred for 100 to 150 minutes at a temperature of 140 to 180°C to form the final composition.

[0005] FR 2 737 216 describes an alternative single-step preparation method. This method uses a ready-to-use precursor mixture comprising an SBS-type elastomer in powder form and crosslinking agents, also in powder form. The precursor mixture is therefore itself a powder.

[0006] US6025418 discloses the addition of a specific sulfur-containing agent in a composition comprising a mixture of bitumen and elastomeric polymer.

[0007] EP384254 and GB2270318 disclose the addition of sulfur in powder form or a sulfur donor agent to a preheated bituminous mixture containing latex or a polymer.

[0008] EP350866 discloses a stock solution containing a hydrocarbon oil and sulfur in crystallized and powdered form. The resulting solution is then added to preheated bitumen.

[0009] None of these documents discloses a vulcanizing agent comprising a sulfur agent and a binder, and which is, as such, in the form of pellets.

[0010] There are several disadvantages associated with all of the methods described above. Two-step processes are more time-consuming and require separate storage of a large number of different components. In addition, since the elastomer and crosslinker are in powder form, they must be added separately. Therefore, their proportions must be adjusted when preparing the bitumen / polymer composition. These methods are therefore prone to numerous errors leading to losses and / or increased production costs. The one-step process overcomes some of these problems, but it is itself associated with other problems. The precursor mixture is in powder form and must be mixed before use because it is composed of several ingredients. Powders also pose safety concerns, as they pose a fire and explosion hazard.This is particularly problematic for sulfur and sulfur-containing compounds. In addition, powders are difficult to store and are prone to clogging and caking, making them difficult to handle.

[0011] WO 02 / 34835 describes a vulcanizing agent for bitumen in the form of pellets. The vulcanizing agent described typically comprises a binder and zinc dibutyldithiocarbamate (ZDBC) as a sulfur-containing agent. The vulcanizing agent is entirely satisfactory from the point of view of preparing a crosslinked bitumen / polymer composition. It is simple to use and allows better control of the quantity of product used in the compositions. Being in the form of pellets, it also makes it possible to overcome the constraints associated with the storage and handling of powders. However, the Applicant has recently discovered that zinc dibutyldithiocarbamate (ZDBC) forming the vulcanizing agent is likely to generate free nitrosamines.However, free nitrosamines are considered by the International Agency for Research on Cancer (IARC) as "possibly carcinogenic to humans" (classified in group 2B). There is therefore a significant risk of danger to operators when handling a vulcanizing agent according to WO 02 / 34835, but also during the preparation and application of bitumen / polymer compositions crosslinked using such a vulcanizing agent.

[0012] There remains a need to provide a safer vulcanizing agent, in which the risk of exposure to carcinogenic compounds for operators is significantly reduced.

[0013] In particular, there remains a need to provide a vulcanizing agent as effective as the vulcanizing agent described in WO 02 / 34835 and whose risk of exposure for operators to carcinogenic compounds is significantly reduced, ideally non-existent.

[0014] An object of the present invention is to solve the problems associated with the above prior art.

[0015] Another object of the present invention is to provide a vulcanizing agent which is simple to use, which allows the preparation of crosslinked bitumen / polymer compositions having good stability, storage and aging characteristics and while presenting a reduced risk of exposure to carcinogenic compounds.

[0016] Another aim of the invention is to provide a vulcanizing agent allowing the preparation of crosslinked bitumen / polymer compositions having improved storage stability compared to the compositions of the prior art, in particular compared to bitumen / polymer compositions crosslinked using a vulcanizing agent such as those described in WO 02 / 34835.

[0017] Summary of the invention

[0018] The invention firstly relates to a vulcanizing agent for vulcanizing bitumen, said vulcanizing agent being in the form of pellets and comprising a sulfur-containing agent and a binder, said sulfur-containing agent comprising zinc dibenzyldithiocarbamate (ZBEC). In particular, the sulfur-containing agent according to the invention further comprises elemental sulfur.

[0019] Preferably, the vulcanizing agent according to the invention comprises at least 20% by mass of binder, relative to the total weight of the vulcanizing agent. More preferably, the vulcanizing agent according to the invention comprises:

[0020] (i) from 20% to 90% by mass of binder,

[0021] (ii) from 10% to 80% by mass of sulfur agent, and

[0022] (iii) from 0% to 30% by mass of additive(s), relative to the total mass of the vulcanizing agent.

[0023] Advantageously, the sulfur agent is a mixture of zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazole (ZMBT), preferably consisting of zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazole (ZMBT).

[0024] Advantageously, the sulfur agent is a mixture of elemental sulfur, zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazole (ZMBT), preferably consists of elemental sulfur, zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazole (ZMBT).

[0025] According to a preferred embodiment, zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazole (ZMBT) are present in a mass ratio ranging from 1:10 to 10:1, preferably from 1:5 to 5:1, preferably equal to 1:1.

[0026] The invention also relates to a process for preparing a vulcanizing agent as defined above and in detail below, the process comprising:

[0027] (a) the extrusion of a sulfur agent with a binder; or

[0028] (b) compressing a sulfur-containing agent with a binder, at a temperature below the melting temperature of the sulfur-containing agent, so as to form pellets of the vulcanizing agent.

[0029] Preferably, the method comprises bringing at least one bitumen base into contact with a copolymer of a monovinyl aromatic hydrocarbon and a conjugated diene and a vulcanizing agent as defined above and in detail below.

[0030] The invention also relates to a crosslinked bitumen / polymer composition comprising: at least one bitumen, at least one elastomer, and at least one vulcanizing agent as defined above and in detail below.

[0031] The invention also relates to a crosslinked bitumen / polymer composition comprising: at least one bitumen, at least one copolymer of a monovinyl aromatic hydrocarbon and a conjugated diene, and at least one vulcanizing agent as defined above and in detail below.

[0032] The above-mentioned copolymers are elastomers within the meaning of the invention. In the present application, the terms “copolymers” and “elastomers” may be used interchangeably.

[0033] Preferably, the composition according to the invention has a variation in penetrability (APene), measured after 3 days of storage at 180°C according to standard EN 1426, less than or equal to 2 1 / 10 mm, preferably less than or equal to 1 1 / 10 mm.

[0034] Preferably, the composition according to the invention has a ring and ball softening temperature variation (ATBA), measured after 3 days of storage at 180°C according to standard EN 1427, of less than or equal to 5°C, preferably less than or equal to 3°C, more preferably less than or equal to 1°C.

[0035] The invention also relates to the use of a crosslinked bitumen / polymer composition as defined above and in detail below, for preparing a surface coating, a hot mix, a cold mix, a gravel emulsion or a wearing course, said crosslinked bitumen / polymer composition being associated with aggregates and / or recycled millings.

[0036] The invention finally relates to the use of a crosslinked bitumen / polymer composition as defined above and in detail below, for preparing a waterproofing coating, a membrane or an impregnation layer.

[0037] Detailed description of the invention

[0038] The invention firstly relates to a vulcanizing agent for vulcanizing bitumen, said vulcanizing agent being in the form of pellets and comprising a sulfur agent comprising zinc dibenzyldithiocarbamate (ZBEC) and a binder.

[0039] According to one embodiment, the sulfur agent further comprises elemental sulfur.

[0040] Zinc dibenzyldithiocarbamate (ZBEC, CAS 14726-36-4) differs from zinc dibutyldithiocarbamate (ZDBC, CAS 136-23-2) by substituting each of the four butyl groups with a benzyl group. Unlike zinc dibutyldithiocarbamate (ZDBC), zinc dibenzyldithiocarbamate (ZBEC) is not likely to generate free nitrosamines. The risk of exposure to carcinogenic compounds in the context of ZBEC is therefore significantly reduced, if any, compared to ZDBC.

[0041] Preferably, the sulfur agent, especially zinc dibenzyldithiocarbamate (ZBEC) is dispersed in the binder. The present invention provides a vulcanizing agent in the form of pellets which avoids the risks associated with powders and can be used in a one-step process to form a crosslinked bitumen / polymer composition, especially useful for the manufacture of a road surface.

[0042] For the purposes of the invention, the term "pellet" means a product comprising particulate matter brought together to form larger agglomerates. These agglomerates are not specifically limited in shape or size, provided they are not in the form of a hazardous powder, and may include an extrudate, tablet or pill, formed by extrusion or compression of the vulcanizing agent. The terms "granule" or "granules" are, in the context of the invention, considered to be synonymous with pellet.

[0043] A one-step process means a process in which the elastomer and vulcanizing agent can be added together to the bitumen, if desired. A two-step process requires that the elastomer and bitumen be well dispersed before the vulcanizing agent is added.

[0044] The various aspects of the present invention will now be discussed in more detail.

[0045] The vulcanizing agent

[0046] The vulcanizing agent according to the invention comprises a binder and a sulfur agent, the proportions of which are not particularly limited, provided that the binder is present in sufficient quantity to allow the formation of pellets.

[0047] In a preferred embodiment, the vulcanizing agent comprises at least 20% by weight of binder.

[0048] Preferably, the vulcanizing agent comprises from 20% to 90% by mass of binder, relative to the total mass of the vulcanizing agent, more preferably from 20% to 50% by mass, even more preferably from 20% to 40% by mass, typically from 25% to 35% by mass.

[0049] Preferably, the vulcanizing agent comprises from 10% to 80% by mass of sulfur-containing agent(s), relative to the total mass of the vulcanizing agent, more preferably from 50% to 80% by mass, even more preferably from 60% to 80% by mass, typically from 65% to 75% by mass.

[0050] According to one embodiment, the vulcanizing agent further comprises one or more additive(s). Preferably, the vulcanizing agent comprises from 0% to 30% by mass of additive(s), relative to the total mass of the vulcanizing agent, more preferably from 0.1% to 10% by mass, even more preferably from 0.5% to 5% by mass, typically from 1% to 2.5% by mass. More preferably, the vulcanizing agent comprises:

[0051] - from 20% to 90% by mass of binder,

[0052] - from 10% to 80% by mass of sulfur agent(s), in particular zinc dibenzyldithiocarbamate (ZBEC), and

[0053] - from 0% to 30% by mass of other additives. Preferably, the sulfur agent comprises from 60% to 99.9% by mass of elemental sulfur, and from 0.1% to 40% by mass of one or more sulfur donor compound(s), relative to the total mass of the sulfur agent.

[0054] More preferably, the sulfur agent comprises from 70% to 99% by mass of elemental sulfur, and from 1% to 30% by mass of one or more sulfur donor compound(s), relative to the total mass of the sulfur agent.

[0055] Even more preferably, the sulfur agent comprises from 80% to 95% by mass of elemental sulfur, and from 5% to 20% by mass of one or more sulfur donor compound(s), relative to the total mass of the sulfur agent.

[0056] Advantageously, the sulfur-containing agent comprises from 90% to 95% by mass of elemental sulfur, and from 5% to 10% by mass of one or more sulfur-donating compound(s), relative to the total mass of the sulfur-containing agent. Preferably, the vulcanizing agent according to the invention comprises from 5% to 75% by mass of elemental sulfur relative to the total mass of the vulcanizing agent, more preferably from 20% to 70% by mass, even more preferably from 50% to 70% by mass, typically from 60% to 70% by mass,

[0057] Preferably, the vulcanizing agent according to the invention comprises from 0.1% to 20% by mass of sulfur donor compound(s) relative to the total mass of the vulcanizing agent, more preferably from 0.5% to 15% by mass, even more preferably from 1% to 10% by mass, typically from 1% to 5% by mass.

[0058] The sulfur-donating compound typically comprises zinc dibenzyldithiocarbamate (ZBEC), alone or in mixtures with other sulfur-donating compounds. Additional sulfur-donating compounds (separate from ZBEC) are described, for example, in the Rubber Handbook published by the Swedish Institute of Rubber Technology. Examples include zinc mercaptobenzothiazole (ZMBT, CAS 155-04-4) or a sulfinamide.

[0059] According to one embodiment, the sulfur donor compound consists essentially of, preferably consisting of, zinc dibenzyldithiocarbamate (ZBEC).

[0060] According to a preferred alternative embodiment, the sulfur donor compound comprises a mixture of zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazol (ZMBT). Preferably, the sulfur donor compound consists essentially of, more preferably consisting of, zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazol (ZMBT).

[0061] Preferably, according to this preferred embodiment, zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazol (ZMBT) are present in a mass ratio ranging from 1:10 to 10:1, more preferably ranging from 1:5 to 5:1, still preferably equal to 1:1.

[0062] Preferably, the sulfur donor compound is free of zinc dibutyldithiocarbamate (ZDBC). More preferably, the sulfur agent is free of zinc dibutyldithiocarbamate (ZDBC). Even more preferably, the vulcanizing agent according to the invention is free of zinc dibutyldithiocarbamate (ZDBC).

[0063] By "free from zinc dibutyldithiocarbamate (ZDBC)" is meant for the purposes of the invention that the product (the sulfur donor compound or the sulfur agent or the vulcanizing agent) comprises less than 0.1% by mass of zinc dibutyldithiocarbamate (ZDBC), relative to the total mass of said product, preferably less than 0.01% by mass, more preferably less than 0.001% by mass.

[0064] According to one embodiment, the sulfur agent comprises, preferably consists essentially of, even more preferably consists of:

[0065] - from 70% to 99% by mass of elemental sulfur, preferably from 80% to 95% by mass, more preferably from 90% to 95% by mass,

[0066] - from 1% to 30% by mass of sulfur donor compound(s), preferably from 5% to 20% by mass, more preferably from 5% to 10% by mass, relative to the total mass of sulfur agent.

[0067] According to a preferred embodiment, the sulfur agent comprises, preferably consists essentially of, even more preferably consists of:

[0068] - from 70% to 99% by mass of elemental sulfur, preferably from 80% to 95% by mass, more preferably from 90% to 95% by mass,

[0069] - from 0.5% to 15% by mass of zinc dibenzyldithiocarbamate (ZBEC), preferably from 2.5% to 10% by mass, more preferably from 2.5% to 5% by mass, and from 0.5% to 15% by mass of zinc mercaptobenzothiazole (ZMBT), preferably from 2.5% to 10% by mass, more preferably from 2.5% to 5% by mass, relative to the total mass of sulfur agent.

[0070] The binder is not particularly limited, provided that it is capable of forming pellets when mixed with the sulfur-containing agent. Preferably, however, the binder has a melting point (and / or softening point) lower than the melting point of sulfur, to facilitate processing. In preferred embodiments, the binder is selected from waxes, hydrocarbon resins, copolymers of ethylene and an acrylic ester, and any mixtures thereof. Preferred binders are selected from polyethylene (PE), glycol monostearate (or GMS for "Glycol MonoStearate" in English), copolymers of ethylene and acrylic esters, and any mixtures thereof. Particularly preferred binders are copolymers of ethylene and vinyl acetate, commonly referred to by the acronym EVA (for "Ethylene-Vinyl Acetate" in English).

[0071] The vulcanizing agent may also include other additives. These additives are not particularly limited and may be added to improve mixing and / or facilitate processing. They may also be chosen to improve surface quality, including road quality. These other additives may include tackifiers, elastomers, bitumens, zinc oxide, and / or stearic acid.

[0072] According to one embodiment, the vulcanizing agent according to the invention comprises from 0% to 30% by mass of additives, relative to the total mass of the vulcanizing agent.

[0073] Among the additives that can be added to the vulcanization composition according to the invention, mention may be made, for example, of colorants, such as carbon black, or tackifying agents.

[0074] For the purposes of the invention, the term "tackifying agent" means a chemical agent capable of increasing the stickiness (or tackiness) of a composition into which it is introduced. Examples that may include polyisobutylenes.

[0075] According to a preferred embodiment, the vulcanizing agent according to the invention further comprises;

[0076] - from 0.1% to 10% by mass of one or more colorant(s), preferably from 0.1% to 5% by mass, more preferably from 0.2% to 1% by mass, typically from 0.3% to 0.5% by mass, and

[0077] - from 0.1% to 20% by mass of one or more tackifying agent(s), preferably from 0.5% to 10% by mass, more preferably from 1% to 5% by mass, relative to the total mass of the vulcanizing agent.

[0078] According to a preferred embodiment, the vulcanizing agent according to the invention comprises, preferably consists essentially of, even more preferably consists of:

[0079] - from 20% to 90% by mass of binder, more preferably from 20% to 50% by mass, even more preferably from 20% to 40% by mass, typically from 25% to 35% by mass, - from 10% to 80% by mass of sulfur agent(s), more preferably from 50% to 80% by mass, even more preferably from 60% to 80% by mass, typically from 65% to 75% by mass, and

[0080] - from 0% to 30% by mass of additive(s), more preferably from 0.1% to 10% by mass, even more preferably from 0.5% to 5% by mass, typically from 1% to 2.5% by mass relative to the total mass of the vulcanizing agent.

[0081] Preferably, the vulcanizing agent according to the invention comprises, preferably consists essentially of, even more preferably of:

[0082] - from 20% to 90% by mass of binder, more preferably from 20% to 50% by mass, even more preferably from 20% to 40% by mass, typically from 25% to 35% by mass,

[0083] - from 5% to 75% by mass of elemental sulfur, more preferably from 20% to 70% by mass, even more preferably from 50% to 70% by mass, typically from 60% to 70% by mass,

[0084] - from 0.1% to 20% by mass of sulfur donor compound(s), more preferably from 0.5% to 15% by mass, even more preferably from 1% to 10% by mass, typically from 1% to 5% by mass, and

[0085] - from 0% to 30% by mass of additive(s), more preferably from 0.1% to 10% by mass, even more preferably from 0.5% to 5% by mass, typically from 1% to 2.5% by mass relative to the total mass of the vulcanizing agent.

[0086] More preferably, the vulcanizing agent according to the invention comprises, preferably consists essentially of, even more preferably of:

[0087] - from 20% to 90% by mass of binder, more preferably from 20% to 50% by mass, even more preferably from 20% to 40% by mass, typically from 25% to 30% by mass,

[0088] - from 5% to 75% by mass of elemental sulfur, more preferably from 20% to 70% by mass, even more preferably from 50% to 70% by mass, typically from 60% to 70% by mass,

[0089] - from 0.05% to 10% by mass of zinc dibenzyldithiocarbamate (ZBEC), more preferably from 0.25% to 7.5% by mass, even more preferably from 0.5% to 5% by mass, typically from 0.5% to 2.5% by mass,

[0090] - from 0.05% to 10% by mass of zinc mercaptobenzothiazole (ZMBT), more preferably from 0.25% to 7.5% by mass, even more preferably from 0.5% to 5% by mass, typically from 0.5% to 2.5% by mass, and - from 0% to 30% by mass of additive(s), more preferably from 0.1% to 10% by mass, even more preferably from 0.5% to 5% by mass, typically from 1% to 2.5% by mass relative to the total mass of the vulcanizing agent.

[0091] Advantageously, the vulcanizing agent according to the invention comprises, preferably consists essentially of, even more preferably of:

[0092] - from 20% to 90% by mass of binder, more preferably from 20% to 50% by mass, even more preferably from 20% to 40% by mass, typically from 25% to 30% by mass,

[0093] - from 5% to 75% by mass of elemental sulfur, more preferably from 20% to 70% by mass, even more preferably from 50% to 70% by mass, typically from 60% to 70% by mass,

[0094] - from 0.05% to 10% by mass of zinc dibenzyldithiocarbamate (ZBEC), more preferably from 0.25% to 7.5% by mass, even more preferably from 0.5% to 5% by mass, typically from 0.5% to 2.5% by mass,

[0095] - from 0.05% to 10% by mass of zinc mercaptobenzothiazole (ZMBT), more preferably from 0.25% to 7.5% by mass, even more preferably from 0.5% to 5% by mass, typically from 0.5% to 2.5% by mass, and

[0096] - from 0.1% to 10% by mass of one or more colorant(s), preferably from 0.1% to 5% by mass, more preferably from 0.2% to 1% by mass, typically from 0.3% to 0.5% by mass, and

[0097] - from 0.1% to 20% by mass of one or more tackifying agent(s), preferably from 0.5% to 10% by mass, more preferably from 1% to 5% by mass, relative to the total mass of the vulcanizing agent.

[0098] Process for manufacturing the vulcanizing agent

[0099] The present invention also relates to a method for manufacturing a vulcanizing agent according to the invention, said method comprising:

[0100] (a) the extrusion of a sulfur agent with a binder; or

[0101] (b) compressing a sulfur-containing agent with a binder, at a temperature below the melting temperature of the sulfur-containing agent, so as to form pellets of the vulcanizing agent.

[0102] The process is a standard compression or extrusion process and is well known in the art. Standard processing techniques and devices may be used. The process preferably uses a temperature of 110°C or less, preferably 100°C or less, since sulfur melts at about 119°C. However, if the sulfur-containing agent as a whole has a melting temperature higher than this, higher temperatures may be used.

[0103] Process for the preparation of a crosslinked bitumen / polymer composition

[0104] The invention also relates to a process for preparing a crosslinked bitumen / polymer composition using a vulcanizing agent according to the invention, as described above.

[0105] The preparation process typically comprises a step of bringing into contact at least one bitumen, at least one elastomer and a vulcanizing agent as defined above.

[0106] In a preferred embodiment, the process is carried out at a temperature of 100°C or higher. More preferably, the process is carried out at a temperature of 120-200°C. As already mentioned above, this is a one-step process where the elastomer and the vulcanizing agent are added substantially simultaneously to the bitumen.

[0107] The bitumen base

[0108] The bitumen(s) used to prepare a bitumen / polymer composition according to the invention are called “bitumen base” and constitute(s) a majority content of the composition, i.e. generally represent(s) at least 70% by mass of the total mass of the bituminous composition, and preferably at least 85%, or even at least 90% by mass of the total mass of the bituminous composition.

[0109] Among the bitumens that can be used according to the invention, mention may firstly be made of bitumens of natural origin, those contained in deposits of natural bitumen, natural asphalt or oil sands and bitumens originating from the refining of crude oil. In the context of the invention, the bitumen(s) used are advantageously chosen from bitumens originating from the refining of crude oil, in particular bitumens containing asphaltenes or pitches. The bitumens can be obtained by conventional processes for the manufacture of bitumens in refineries, in particular by direct distillation and / or vacuum distillation of oil. These bitumens can optionally be visbroken and / or deasphalted and / or rectified in air. It is common practice to carry out vacuum distillation of atmospheric residues originating from the atmospheric distillation of crude oil.This manufacturing process therefore corresponds to the succession of atmospheric distillation and vacuum distillation, the feedstock feeding the vacuum distillation corresponding to the atmospheric residues. These vacuum residues from the vacuum distillation tower can also be used as bitumens. It is also common to inject air into a feedstock usually composed of distillates and heavy products from the vacuum distillation of atmospheric residues from the distillation of oil. This process makes it possible to obtain a blown, or semi-blown, or oxidized, or air-rectified, or partially air-rectified bitumen.

[0110] Different bitumens obtained by refining processes can be combined in the compositions according to the invention, to obtain the best compromise, in terms of technical performances. In conventional processes for mixing different bitumens, the operation is carried out at temperatures between 100°C and 200°C, preferably between 140°C and 200°C, and with stirring for a period of at least 10 minutes, preferably between 30 minutes and 10 hours, more preferably between 1 hour and 6 hours. The temperature and duration of heating vary according to the quantity of bitumen used and are defined by standard NF EN 12594. Blown bitumens can be manufactured in a blowing unit, by passing a flow of air and / or oxygen through a starting bitumen or bitumen mixture. This operation can be carried out in the presence of an oxidation catalyst, for example phosphoric acid.

[0111] Generally, blowing is carried out at high temperatures, in the order of 200 to 300°C, for relatively long periods of time, typically between 30 minutes and 2 hours, continuously or in batches. The blowing time and temperature are adjusted according to the desired properties of the blown bitumen and the quality of the starting bitumen.

[0112] Among the bitumens that can be used according to the invention, recycling bitumens can also be mentioned.

[0113] Bitumens can be hard grade bitumens (such as grades 10 / 20 and 20 / 30) or soft grade bitumens (such as grade 160 / 220) as defined by EN 12591.

[0114] The invention is particularly suitable for cases where the bitumen base consists of a hard grade bitumen or a mixture of hard grade bitumens, in particular chosen from bitumens of grade 35 / 50, 20 / 30 and 10 / 20.

[0115] The bitumen bases that can be used in the context of the invention preferably have a penetrability, measured at 25°C according to standard EN 1426, of 5 to 330 1 / 10 mm, preferably between 10 and 220 1 / 10 mm, more preferably from 10 to 120 1 / 10 mm. In a well-known manner, the measurement known as “needle penetrability” is carried out by means of a standardized test NF EN 1426 at 25°C (P25). This penetrability characteristic is expressed in tenths of a millimeter (dmm or 1 / 10 mm). The needle penetrability, measured at 25°C, according to the standardized test NF EN 1426, represents the measurement of the penetration into a sample of bitumen, after a time of 5 seconds, of a needle whose weight with its support is 100 g.

[0116] The Elastomer The elastomer is not particularly limited provided that it has the qualities required for coating compositions. Such elastomers are well known in the art and are generally rubbery polymers. In a preferred embodiment, the elastomer comprises styrene butadiene styrene (SBS), hydrogenated SBS, styrene isoprene styrene (SIS), styrene ethylene butadiene styrene (SEBS) and / or polyisobutadiene (PIB).

[0117] Preferably, the elastomer is typically selected from copolymers of a monovinyl aromatic hydrocarbon and a conjugated diene.

[0118] Preferably, the elastomer is chosen from block copolymers of formula S-BS, in which:

[0119] - each S, which may be identical or different, independently represents a block based on monovinyl aromatic hydrocarbon monomers,

[0120] - B represents a block based on butadiene monomers, said block B comprising pendant vinyl groups.

[0121] For the purposes of the invention, the term "block" means a polymer chain obtained by the polymerization of one or more monomers of the same chemical nature. A block is advantageously made up of the repetition of the same monomer.

[0122] In said block copolymers of formula SBS, the S blocks together represent at least 15 mol% of the total number of moles of monomeric units of the block copolymer. Said block copolymers have a weight-average molecular mass ranging from 40,000 to 500,000 g / mol and have a content of pendant vinyl groups contained in the B block, which is greater than or equal to 20 mol%, relative to the total number of moles of monomeric units of the block copolymer. These copolymers may be called, more simply, hereinafter, SBS elastomer. In general, the two S blocks of the heat-crosslinkable SBS elastomer are identical.

[0123] In the context of the invention, butadiene means 1,3-butadiene which is a conjugated diene. When butadiene, or more generally a conjugated diene, is polymerized via a 1,2-addition mechanism, the result is a vinyl group (also called a vinyl group) pendant relative to the backbone of the polymer. The pendant vinyl groups of the SBS block copolymer therefore correspond to the 1,2-addition polymerization of the conjugated diene monomers, and in particular of the majority butadiene monomers, within the B block. The units obtained by the polymerization of butadiene according to a 1,2-addition mechanism or according to a 1,4-addition mechanism have the same molar mass.

[0124] In particular, the monovinyl aromatic hydrocarbon monomer(s) present in the S blocks of the SBS heat-crosslinkable elastomer are chosen from styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, alpha-methylstyrene, vinylnaphthalene, vinyltoluene and vinylxylene or mixtures thereof. The preferred monovinyl aromatic hydrocarbon monomer according to the present invention is styrene, which is used, for the constitution of the S blocks as the sole monomer, or as the major monomer in mixtures with minor proportions of one or more other monomers such as o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, alpha methylstyrene, vinylnaphthalene, vinyltoluene and vinylxylene, namely, in proportions of at most 10% by mass, relative to the totality of the monovinyl aromatic hydrocarbon monomers present in said S blocks.The use of styrene as the sole monomer is particularly preferred in the present invention for the constitution of the S blocks of the SBS elastomer. Thus, the monovinylaromatic hydrocarbon monomers from which the S blocks of the SBS copolymers with thermally crosslinkable blocks are derived may be, independently, any monovinylaromatic hydrocarbon monomer as previously described and are preferably styrene.

[0125] The block B based on butadiene monomers entering into the composition of the mentioned block copolymers SBS is, preferably, solely composed of butadiene monomers, or of a mixture of butadiene comprising minor proportions of one or more other structurally related conjugated dienes, and in particular chosen from isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and 1,3-hexadiene, in particular representing at most 10% by mass, relative to the totality of the conjugated dienes present in the block B. Preferably, the monomers constituting the block B are exclusively butadiene monomers.

[0126] The SBS heat-crosslinkable block elastomer used in the context of the invention has a weight-average molecular mass Mw, ranging from 40,000 to 500,000 g / mol. Preferably, the SBS heat-crosslinkable block elastomer has a weight-average molecular mass Mw, less than or equal to 400,000 g / mol, more preferably less than or equal to 250,000 g / mol, even more preferably less than or equal to 200,000 g / mol and advantageously less than or equal to 150,000 g / mol.

[0127] Preferably, the SBS block copolymer used in the context of the invention has a weight-average molecular mass Mw greater than or equal to 50,000 g / mol, more preferably greater than or equal to 65,000 g / mol, even more preferably greater than or equal to 75,000 g / mol, and advantageously greater than or equal to 100,000 g / mol. According to particular embodiments, the SBS block copolymer has a weight-average molecular mass Mw in any range corresponding to the maximum and minimum values ​​mentioned above, and advantageously in the range from 100,000 to 150,000 g / mol.

[0128] As indicated above, the SBS block copolymer used in the context of the invention has a content of pendant vinyl groups greater than or equal to 5% by mole, relative to the total number of moles of monomeric units of the copolymer. This vinyl content, determined by coupling 13C NMR (carbon nuclear magnetic resonance) and 1H NMR (proton nuclear magnetic resonance) spectroscopy techniques, makes it possible to characterize the polymer.

[0129] Preferably, the SBS block copolymer preferably has a content of pendant vinyl groups greater than or equal to 5% by mole, relative to the total number of moles of monomeric units of the SBS copolymer, preferably greater than or equal to 10%.

[0130] According to one embodiment, the SBS block copolymer preferably has a content of pendant vinyl groups less than or equal to 50 mol%, relative to the total number of moles of monomeric units of the SBS copolymer, more preferably less than or equal to 40 mol%, even more preferably less than or equal to 30 mol%, typically less than or equal to 20 mol%.

[0131] Advantageously according to this first embodiment, the SBS block copolymer has a content of pendant vinyl groups in any range corresponding to the maximum and minimum values ​​mentioned above, and advantageously in the range from 5% to 20% by mole.

[0132] According to a second embodiment, the SBS block copolymer used according to the invention preferably has a content of pendant vinyl groups greater than or equal to 25 mol%, relative to the total number of moles of monomeric units of the SBS copolymer, more preferably greater than or equal to 30 mol%.

[0133] Preferably, according to this second embodiment, the SBS block copolymer used according to the invention preferably has a content of pendant vinyl groups less than or equal to 50 mol%, relative to the total number of moles of monomeric units of the SBS copolymer, more preferably less than or equal to 45 mol%. Advantageously according to this second embodiment, the SBS block copolymer has a content of pendant vinyl groups in any range corresponding to the maximum and minimum values ​​mentioned above, and advantageously in the range from 35% to 45 mol%. Preferably, the pendant vinyl groups are distributed along the B block of the SBS polymer in a statistical manner. This characteristic results directly from the process implemented for the synthesis of the copolymer.

[0134] The number of moles of monomeric units of the S blocks present in the SBS block copolymer represents, together, at least 15% of the total number of moles of monomeric units of the SBS copolymer, preferably at least 16% by mole.

[0135] Preferably, the number of moles of monomeric units of the S blocks of the SBS polymer represents, together, from 15% to 50% by mole, relative to the total quantity of moles of monomeric units of the SBS block copolymer, more preferably from 16% to 30% by mole, even more preferably from 16% to 25% by mole, and advantageously from 16% to 20% by mole. The number of moles of monomeric units of the S blocks of the SBS polymer can be determined by 13C NMR spectroscopy (Carbon Nuclear Magnetic Resonance).

[0136] Preferably, the monovinyl aromatic hydrocarbon monomer (advantageously styrene) content of the SBS block copolymer, determined by NMR spectroscopy 13C (Carbon Nuclear Magnetic Resonance), is greater than or equal to 25% by mass, more preferably greater than or equal to 28% by mass, even more preferably greater than or equal to 30% by mass, relative to the total mass of the block copolymer of formula SBS.

[0137] Preferably, the monovinyl aromatic hydrocarbon monomer (advantageously styrene) content of the SBS block copolymer, determined by NMR spectroscopy 13 C (Carbon Nuclear Magnetic Resonance), ranges from 25% to 40% by mass, even more advantageously from 28% to 35% by mass, relative to the total mass of the SBS block copolymer.

[0138] Advantageously, SBS block elastomers are in an essentially non-hydrogenated form.

[0139] According to a particular embodiment, the block copolymer of formula SBS is obtained by coupling two block copolymers of formula S-B' in which the blocks S and B' are chosen to obtain an SBS block copolymer. The block B may therefore include a residue of a coupling agent, well known in the field in question. As examples of difunctional coupling agents, mention may be made of dibromoethane, diethyl adipate, divinylbenzene, dimethyldichlorosilane and methyl dichlorosilane.

[0140] Preferably, according to this particular embodiment, the efficiency of the coupling of the two block copolymers of formula S-B', measured by gel permeation chromatography, is greater than or equal to 50%, more preferably greater than or equal to 75%, even more preferably greater than or equal to 90% and advantageously greater than or equal to 95%.

[0141] Examples of SBS block copolymers which can be used in the compositions according to the invention, as well as their preparation processes, are described in particular in patent US 5,798,401, as well as in document WO 2007 / 058994 and by the applicant in patent application WO 201 1 / 013073.

[0142] It is possible that, in the bituminous compositions and the processes according to the invention, a single SBS block copolymer as described in the context of the invention is used, or that a mixture of SBS block copolymers as described in the context of the invention is used, or that one or more SBS block copolymer(s) as described in the context of the invention are used in combination with one or more other elastomers. According to a preferred variant, the matrix is ​​produced with only one or more, preferably a single, SBS elastomer. The latter preferably represents from 0.5 to 10% by mass, in particular from 1 to 6% by mass, and preferably from 1.5 to 4% by mass of the total mass of the bituminous composition. In the bituminous compositions according to the invention, said elastomer(s) is / are in a crosslinked form, but this does not affect the percentage that it / they represent within the composition.In other words, the percentages, before and after crosslinking, of the different components used for the preparation of the bituminous composition, are identical. When a mixture of elastomers, containing at least one elastomer other than the SBS elastomer as described in the context of the invention is used, the percentages of 0.5 to 10% by mass, in particular of 1 to 6% by mass, and preferably of 1.5 to 4% by mass given relative to the total mass of the bituminous composition, correspond to the total quantity of elastomers used (SBS + other elastomer(s)). In this case of use of a mixture of elastomers, containing at least one elastomer other than the SBS elastomers, the SBS elastomer represents at least 50%, preferably at least 70% by mass, and preferentially at least 90% of the total quantity of elastomers used (SBS + other elastomer(s)).

[0143] Preferably, the SBS elastomer(s) represent at least 80% by mass of the total quantity of elastomers, preferably at least 90% and preferentially at least 95% of the total quantity of elastomers present, if a mixture of elastomers is used to prepare the bituminous compositions according to the invention. In particular, it is possible for the mixture to contain a portion of S-B' used during the manufacture of the SBS elastomer by coupling, as explained previously.

[0144] The crosslinked bitumen / polymer composition according to the invention preferably comprises from 1% to 10% by mass of elastomer, in particular of monovinyl aromatic hydrocarbon and conjugated diene copolymer, in particular of styrene and butadiene copolymer, relative to the mass of the crosslinked bitumen / polymer composition, more preferably from 2% to 8%, even more preferably from 3% to 5%.

[0145] The crosslinked bitumen / polymer composition

[0146] Preferably, the crosslinked bitumen / polymer composition comprises from 0.01% to 5% by mass of the vulcanizing agent according to the invention, relative to the total mass of the crosslinked bitumen / polymer composition, more preferably from 0.05 to 1% by mass, even more preferably from 0.10% to 0.50% by mass.

[0147] Preferably, the crosslinked bitumen / polymer composition comprises, preferably consists essentially of, typically consists of:

[0148] - from 70% to 99% by mass of bitumen,

[0149] - from 1 to 10% by mass of elastomer, and

[0150] - from 0.01% to 5% by mass of vulcanizing agent according to the invention, relative to the total mass of the bitumen / polymer composition.

[0151] More preferably, the crosslinked bitumen / polymer composition comprises, preferably consists essentially of, typically consists of:

[0152] - from 85% to 98% by mass of bitumen,

[0153] - from 2 to 8% by mass of elastomer, and

[0154] - from 0.05% to 1% by mass of vulcanizing agent according to the invention, relative to the total mass of the bitumen / polymer composition.

[0155] Advantageously, the crosslinked bitumen / polymer composition comprises, preferably consists essentially of, typically consists of:

[0156] - from 90% to 97% by mass of bitumen,

[0157] - from 3 to 7% by mass of elastomer, and

[0158] - from 0.10% to 0.5% by mass of vulcanizing agent according to the invention, relative to the total mass of the bitumen / polymer composition.

[0159] Preferably, the crosslinked bitumen / polymer composition comprises, preferably consists essentially of, typically consists of:

[0160] - from 70% to 99% by mass of bitumen,

[0161] - from 1 to 10% by mass of copolymer of a monovinyl aromatic hydrocarbon and a conjugated diene, and

[0162] - from 0.01% to 5% by mass of vulcanizing agent according to the invention, relative to the total mass of the bitumen / polymer composition.

[0163] More preferably, the crosslinked bitumen / polymer composition comprises, preferably consists essentially of, typically consists of:

[0164] - from 85% to 98% by mass of bitumen, - from 2 to 8% by mass of copolymer of a monovinyl aromatic hydrocarbon and a conjugated diene, and

[0165] - from 0.05% to 1% by mass of vulcanizing agent according to the invention, relative to the total mass of the bitumen / polymer composition.

[0166] Advantageously, the crosslinked bitumen / polymer composition comprises, preferably consists essentially of, typically consists of:

[0167] - from 90% to 97% by mass of bitumen,

[0168] - from 3 to 7% by mass of copolymer of a monovinyl aromatic hydrocarbon and a conjugated diene, and

[0169] - from 0.10% to 0.5% by mass of vulcanizing agent according to the invention, relative to the total mass of the bitumen / polymer composition.

[0170] The applications

[0171] Various uses of the crosslinked bitumen / polymer compositions according to the invention are envisaged. In particular, the crosslinked bitumen / polymer compositions of the invention can be used for the preparation of a bitumen / polymer binder. The bitumen / polymer binder according to the invention can be used in association with aggregates, in particular road aggregates.

[0172] Preferably, the bituminous composition according to the invention is used, optionally in a mixture with recycled bituminous aggregates or aggregates, to manufacture a surface dressing, a hot mix, a cold mix, a cold-poured mix, an emulsion gravel, a base layer, a bonding layer, a tack layer or a wearing course. These applications relate in particular to bituminous mixes as materials for the construction and maintenance of road bodies and their surfacing, as well as for carrying out all road works. Other combinations of the bituminous composition and the aggregate having particular properties may be mentioned, such as anti-rutting layers, draining mixes, or asphalts (mixture between a bituminous binder and aggregates of the sand type).With regard to road applications, the invention relates in particular to bituminous coatings as materials for the construction and maintenance of road surfaces and their surfacing, as well as for carrying out all road works.

[0173] Bituminous coating means a mixture of a bituminous binder with aggregates and possibly mineral and / or synthetic fillers.

[0174] The bituminous mix comprises a crosslinked bitumen / polymer composition according to the invention, and optionally mineral and / or synthetic fillers, preferably chosen from fines, sand, gravel and recycled millings. The aggregates are mineral and / or synthetic aggregates, in particular recycled millings, with dimensions greater than 2 mm, preferably between 2 mm and 20 mm.

[0175] The crosslinked bitumen / polymer composition according to the invention can advantageously be used to prepare a surface coating, a hot mix, a warm mix, a cold mix, a cold-poured mix or a heavy emulsion.

[0176] With regard to road applications, the invention also relates to asphalts as materials for manufacturing and covering sidewalks.

[0177] Asphalt means a mixture of bituminous binder with mineral and / or synthetic fillers.

[0178] An asphalt comprises a crosslinked bitumen / polymer composition according to the invention and mineral fillers such as fines, sand or gravel and / or synthetic fillers. The mineral fillers consist of fines (particles with dimensions less than 0.063 mm), sand (particles with dimensions between 0.063 mm and 2 mm) and optionally gravel (particles with dimensions greater than 2 mm, preferably between 2 mm and 4 mm).

[0179] Asphalts have 100% compaction and are primarily used to make and cover pavements, while asphalts have a compaction of less than 100% and are used to make roads. Unlike asphalts, asphalts are not compacted with a roller during installation.

[0180] Another aspect of the invention is the use of a crosslinked bitumen / polymer composition according to the invention in various industrial applications, in particular for preparing an interior or exterior coating, a membrane or an impregnation layer.

[0181] With regard to the industrial applications of the bituminous compositions according to the invention, mention may be made of the manufacture of waterproofing membranes, vibration damping membranes, thermal and / or sound insulation membranes, surface coverings, carpet tiles, impregnation layers.

[0182] The invention also relates to the use of bitumen / polymer binders, coated materials and poured asphalts according to the invention for the manufacture of road surfaces, pavements, sidewalks, roads, urban developments, soils, waterproofing of buildings or structures, in particular for the manufacture in road applications, of foundation layers, base layers, base layers, surface layers such as binder layers and / or wearing courses.

[0183] The present invention will now be described with reference to the following specific embodiments, which are given by way of example only and are not intended to limit the invention. EXAMPLES:

[0184] Evaluation of bituminous compositions

[0185] In the following examples, the bituminous compositions are evaluated by:

[0186] - measurement of needle penetrability at 25°C (abbreviation: P25), according to standard EN 1426, the results being expressed in 1 / 10 mm,

[0187] - measurement of the ring-ball softening temperature (abbreviation: TBA), according to standard EN 1427, the results being expressed in °C,

[0188] - Storage stability: The storage stability of the concentrated compositions prepared above is evaluated by measuring the difference in penetrability ((APene) and the difference in TBA (ATBA) of each composition after 3 days of storage at 180°C.

[0189] - Elastic return at 25°C (R25): unit = %, standard EN 13398,

[0190] Raw materials

[0191] The examples were made with the following raw materials:

[0192] Bitumen Base (B): grade 35 / 50 bitumen with a P25 penetrability of 40 1 / 10 mm and a TBA of 52°C, commercially available from the TOTAL group under the AZALT® brand.

[0193] SBS (E) heat-crosslinkable elastomer styrene / butadiene / styrene (SBS) block copolymer, comprising 30.5% by mass of styrene and 69.5% by mass of butadiene. The content of pendant vinyl groups resulting from the 1,2-addition polymerization of butadiene is 27.8% by mass relative to the total mass of copolymer. The copolymer has a weight-average molecular weight (Mw) of 142,500 Daltons and a polydispersity index Ip of 1.09. This copolymer is commercially available from the company KRATON under the name D 1 192.

[0194] Vulcanizing agent A1 according to WO 02 / 34835 (comparative) comprising 29.6% by mass of binder, 68% by mass of sulfur agent including 2% by mass of zinc dibutyldithiocarbamate (ZDBC), and 2.4% by mass of additives.

[0195] Vulcanizing agent A2 (according to the invention): Vulcanizing agent A2 corresponds to vulcanizing agent A1 defined above, except that zinc dibutyldithiocarbamate (ZDBC) has been replaced by zinc dibenzyldithiocarbamate (ZBEC).

[0196] Preparation of compositions

[0197] Compositions C1* and C2 are prepared according to the following protocol:

[0198] The pure bitumen is first heated to 160°C in an oven, then transferred to a 3L reactor in which it is heated for 1 hour at 180°C. The elastomer and the vulcanizing agent are then added and the mixture ground for 30 min at 6000 rpm, still at 180°C, using a high shear rotorstator (Silverson).

[0199] The reactor is then placed under mechanical stirring at 400 rpm for 2 hours at 180°C.

[0200] This gives the thermo-crosslinked matrix of the bituminous composition.

[0201] The details of compositions C1* and C2 are given in the following table 1. The contents are given by mass relative to the total mass of the crosslinked bitumen / polymer composition.

[0202] The C1* composition is comparative.

[0203] Composition C2 is according to the invention.

[0204] Properties of compositions

[0205] The properties of compositions C1* and C2 were evaluated according to the protocols defined above. The results are summarized in Table 2 below. Compositions C1* and C2 thus have equivalent properties. Thus, replacing zinc dibutyldithiocarbamate (ZDBC) of the prior art with zinc dibenzyldithiocarbamate (ZBEC, CAS 136-23-2) does not in any way impair the performance of the vulcanizing agent. On the contrary, it is observed that the composition according to the invention has a lower ring and ball softening temperature (RBT) than the comparative composition obtained from a vulcanizing agent according to the prior art. This reduction in RBT results in a lower application temperature and therefore a reduction in the energy required for its application. In addition, composition C2 according to the invention has improved storage stability compared to composition C1*. Indeed, the TBA of composition C2 according to the invention only varies by 0.5°C after 3 days of storage at 180°C, while the TBA of composition C1* varies by 5.0°C under the same conditions.

Claims

CLAIMS 1. A vulcanizing agent for vulcanizing bitumen, said vulcanizing agent being in the form of pellets and comprising a sulfur-containing agent and a binder, said sulfur-containing agent comprising zinc dibenzyldithiocarbamate (ZBEC).

2. Vulcanizing agent according to claim 1, comprising at least 20% by mass of binder, relative to the total weight of the vulcanizing agent.

3. Vulcanizing agent according to claim 1 or claim 2, comprising: (i) from 20% to 90% by mass of binder, (ii) from 10% to 80% by mass of sulfur agent, and (iii) from 0% to 30% by mass of additive(s), relative to the total mass of the vulcanizing agent.

4. Vulcanizing agent according to any one of the preceding claims, wherein the sulfur agent is a mixture of zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazole (ZMBT), preferably consists of zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazole (ZMBT).

5. Vulcanizing agent according to claim 4, in which zinc dibenzyldithiocarbamate (ZBEC) and zinc mercaptobenzothiazole (ZMBT) are present in a mass ratio ranging from 1:10 to 10:1, preferably from 1:5 to 5:1, preferably equal to 1:

1.

6. A process for preparing a vulcanizing agent according to any one of the preceding claims, the process comprising: a) extruding a sulfur-containing agent with a binder; or (b) compressing a sulfur-containing agent with a binder, at a temperature below the melting temperature of the sulfur-containing agent, so as to form pellets of the vulcanizing agent.

7. A process for preparing a crosslinked bitumen / polymer composition, said process comprising bringing at least one bitumen base into contact with a copolymer of a monovinyl aromatic hydrocarbon and a conjugated diene and a vulcanizing agent according to any one of claims 1 to 5.

8. Crosslinked bitumen / polymer composition comprising: at least one bitumen, at least one copolymer of a monovinyl aromatic hydrocarbon and a conjugated diene, and at least one vulcanizing agent according to any one of claims 1 to 5.

9. Crosslinked bitumen / polymer composition according to claim 8, having a variation in penetrability (APene), measured after 3 days of storage at 180°C according to standard EN 1426, less than or equal to 2 1 / 10 mm, preferably less than or equal to 1 1 / 10 mm.

10. Crosslinked bitumen / polymer composition according to claim 8 or claim 9, having a variation in ring and ball softening temperature (ATBA), measured after 3 days of storage at 180°C according to standard EN 1427, less than or equal to 5°C, preferably less than or equal to 3°C, more preferably less than or equal to 1°C.

11. Use of a crosslinked bitumen / polymer composition according to any one of claims 8 to 10, for preparing a surface coating, a hot mix, a cold mix, a gravel emulsion or a wearing course, said crosslinked bitumen / polymer composition being associated with aggregates and / or recycled millings.

12. Use of a crosslinked bitumen / polymer composition according to any one of claims 8 to 10, for preparing a waterproofing coating, a membrane or an impregnation layer.

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