Title of Invention

"PROCESS FOR THE PREPARATION OF BITUMEN/POLYMER COMPOSITIONS"

Abstract

The present invention relates to Process for the preparation of bitumen/polymer compositions exhibiting, inter alia, a very low temperature susceptibility, in which a bitumen or mixture of bitumens is brought into contact, the operation being carried out at temperatures of between 100°C and 230°C and with stirring, for a period of at least 10 minutes, with 0.01% to 20%, of at least by weight of the bitumen or mixture of bitumens, one olefinic polymer carrying epoxy or COOH functional groups in the range of 0.05 to 10% by weight, to form bitumen/polymer component, said process being wherein 0.005% to 6%, by weight of the bitumen or mixture of bitumens, of an acidic adjuvant is incorporated in the bitumen/polymer component, which is maintained at temperatures of between 100°C and 230°C and with stirring, and the reaction mixture thus formed is maintained at temperatures of between 100°C and 230°C with stirring for a period of at least 10 minutes to produce the bitumen/polymer composition, the said acidic adjuvant being composed of one or more compounds chosen from the group formed by phosphoric acids, boric acids, sulphuric acid, the anhydrides of the said acids, chlorosulphuric acid, polyphosphoric acids, phosphonic acids of formula and acids of formula R-(COO)t-SO3H with, in the said formulae, t taking the value zero or one and R denoting a monovalent hydrocarbon radical chosen from the group composed of acyclic monovalent C1 to C16 hydrocarbon radicals and cyclic monovalent hydrocarbon radicals containing 4 to 12 cyclic carbon atoms and optionally substituted by cyclic monovalent C1 to C16 hydrocarbon radicals.

Full Text

The invention relates to a process for the preparation of bitumen/polymer compositions of very low temperature susceptibility. It further relates to the application of the compositions obtained to the production of bitumen/polymer binders for the preparation of coatings, and in particular of road surfacings, of bituminous mixes or else of watertight facings. It is known to employ bituminous compositions as various surface coatings and especially as road surfacings, on condition that these compositions have a certain number of essential mechanical properties. These mechanical properties are in practice assessed by determining, using standardized tests, a series of mechanical characteristics, the most widely employed of which are the following: softening point, expressed in °C and determined by the ring-and-ball test defined by NF Standard T 66008, brittleness point, or Fraass point, expressed in °C and determined according to IP Standard 80/53, penetrability, expressed in 1/10 of a mm and determined according to NF Standard T 66004, tensile rheological characteristics, determined according to NF Standard T 46002, and comprising the quantities: • yield stress σy/ in bars, • yield elongation εy, in %, • breaking stress σb, in bars, • elongation at break εb, in %. An indication of the temperature susceptibility of the bituminous compositions can also be obtained from a correlation between the penetrability (abbreviated to pen) and the softening point (abbreviated to RBT) of the said compositions, known by the name of Pfeiffer's number (abbreviated to PN). This number is calculated using the relation: (Formula Removed) in which A is the slope of the straight line represented by the equation: (Formula Removed) The temperature susceptibility of the bituminous composition is proportionally lower the greater the value of Pfeiffer's number or, what amounts to the same thing, the lower the value of the quantity A. In the case of conventional bitumens, Pfeiffer's number assumes values which lie in the neighbourhood of zero. In general, conventional bitumens do not simultaneously exhibit the combination of the required properties and it has been known for a long time that the addition of various polymers to these conventional bitumens allows the mechanical properties of the latter to be favourably modified and bitumen/polymer compositions to be formed which have mechanical properties that are improved in relation to those of bitumens alone. The incorporation of olefinic polymers functionalized by epoxy or carboxyl groups in bituminous compositions composed of one or more bitumens or composed of one or more bitumens and of one or more polymers not containing such groups results in the production of bitumen/polymer compositions, the consistency (increase in the ring-and-ball softening point), the temperature susceptibility (increase in Pfeiffer's number) and the tensile mechanical properties of which are significantly improved. Such bitumen/polymer compositions, which contain olefinic polymers functionalized by epoxy or carboxyl groups, are described in particular in references US-A-4,650,820, US-A-5,306,750 and US-A-5,331,028, as well as the French patent application filed by the Applicant Company on 10.11.1994 under the number 9413537. Thus, the reference US-A-4,650,820 relates to a bitumen/polymer composition containing, by weight, 95% to 99% of a bitumen having a pseudoviscosity at 30°C within the range 200 to 1000 seconds and 1% to 5% of a terpolymer composed of 88 molar % to 98.7 molar % of units deriving from ethylene, of 1 molar % to 10 molar % of units deriving from at least one Cx to C6 alkyl acrylate or methacrylate and of 0.3% to 3% of units deriving from maleic anhydride. The reference US-A-5,306,750 describes a bitumen/polymer composition composed of a reaction product obtained by bringing a bitumen into contact, at temperatures of 125°C to 250°C and with stirring, for a period of time of the order of 3 hours to 48 hours, with an ethylene copolymer containing, by weight, 0.1% to 20% of glycidyl groups, the quantity of the copolymer representing 0.05% to 20% of the weight of the composition. In particular, the ethylene copolymer containing glycidyl groups is a random ethylene copolymer containing 0.5 to 15% by weight of a monomer containing a glycidyl group, in particular glycidyl acrylate or methacrylate, and containing 0 to 50% by weight of a vinyl monomer not containing a glycidyl group, such as a vinyl ester, for example vinyl acetate, or an alkyl acrylate or methacrylate. The reference US-A-5,331,028 relates to a bitumen/polymer composition of a type comparable with that described in the reference US-A-5,306,750 but additionally containing 0.3% to 20% by weight of a block copolymer of styrene and of a conjugated diene, for example block copolymer of styrene and of butadiene, having a weight-average molecular mass ranging from 100,000 to 1,000,000. The subject of French Patent Application No. 9413537 is a bitumen/polymer composition obtained by bringing a bitumen or mixture of bitumens, a sulphur-crosslinkable elastomer such as, in particular, a block copolymer of styrene and of a conjugated diene, an olefinic polymer containing epoxy or carboxyl (COOH) functional groups and a sulphur-donor coupling agent into contact between 100°C and 230°C and with stirring. It has now been found that the beneficial effect of olefinic polymers containing epoxy or COOH functional groups on improving the mechanical and rheological characteristics, in particular consistency, temperature susceptibility and tensile mechanical properties, of bitumen/polymer compositions containing these functional polymers could be further substantially improved by treating the said compositions, after having prepared them, with a specific adjuvant of the acid or acid anhydride type. The subject of the invention is therefore a process for the preparation of bitumen/polymer compositions exhibiting, inter alia, a very low temperature susceptibility, in which a bitumen or mixture of bitumens is brought into contact, the operation being carrried out at temperatures of between 100°C and 230°C and with stirring, for a period of time of at least 10 minutes, with 0.01% to 20%, preferably 0.05% to 10% and more especially 0.1% to 6%, calculated by weight of the bitumen or mixture of bitumens, of at least one olefinic polymer carrying epoxy or COOH functional groups, in order to form a reaction product known as bitumen/polymer component, the said process being characterized in that 0.005% to 6% and preferably 0.01% to 3%, by weight of the bitumen or mixture of bitumens, of an acidic adjuvant is incorporated in the bitumen/polymer component, which is maintained at temperatures of between 100°C and 230°C and with stirring, and the reaction mixture thus formed is maintained at temperatures of between 100°C and 230°C and with stirring for a period of time of at least 10 minutes in order to produce the bitumen/polymer composition, the said acidic adjuvant being composed of one or more compounds chosen from the group formed by phosphoric acids, boric acids, sulphuric acid, the anhydrides of the said acids, chlorosulphuric acid, polyphosphoric acids, phosphonic acids of formula (Formula Removed) and acids of formula R- (COO) t-S03H with, in the said formulae, t taking the value zero or one and R denoting a monovalent hydrocarbon radical chosen from the group composed of acyclic monovalent C1 to C16 hydrocarbon radicals and cyclic monovalent hydrocarbon radicals containing 4 to 12 cyclic carbon atoms and optionally substituted by acyclic monovalent C1 to C16 hydrocarbon radicals. In particular, the acidic adjuvant may be taken from the compounds H3P04, P205, H3BO3, B2O3, H2S04, S03 and HSO3C1 or alternatively from polyphosphoric acids, mixtures of at least one polyphosphoric acid and of sulphuric acid, mixtures of at least one polyphosphoric acid and of at least one of the said acids R-(COO)t-S03H, mixtures of sulphuric acid and of at least one of the acids R- (COO) t-S03H and mixtures of sulphuric acid with at least one polyphosphoric acid and at least one of the acids R- (COO) t-S03H. When the acidic adjuvant is based on one or more polyphosphoric acids, it may contain, by weight, 5% to 100% and more particularly 20% to 100% of one or more polyphosphoric acids and 95% to 0% and more particularly 80% to 0% of at least one compound chosen from the group formed by sulphuric acid and the acids R-(COO) t-S03H. Very especially, this type of acidic adjuvant consists of a combination composed, by weight, of 20% to 95% and more particularly of 40% to 90% of one or more polyphosphoric acids and of 80% to 5% and more particularly of 60% to 10% of sulphuric acid and/or of methanesulphonic acid. When the acidic adjuvant is composed of a plurality of acidic compounds, the said compounds may be incorporated in the bitumen/polymer component either as a mixture or separately. The polyphosphoric acids which may be employed in the process according to the invention are compounds of empirical formula PqHrOg in which q, r and s are positive numbers such that q > 2 and in particular ranging from 3 to 20 or more and such that 5q + r - 2s = 0. In particular, the said polyphosphoric acids may be linear compounds of empirical formula PqHq+203q+1 corresponding to the expanded formula (Formula Removed) where q has the meaning given above, or alternatively be products with a two-dimensional structure, indeed even a three-dimensional structure. All these polyphosphoric acids may be regarded as products of the polycondensation, by heating, of aqueous metaphosphoric acid. The acids of formula R-(COO) t-S03H are either sulphonic acids of formula R-SO3H, when t = 0, or else acids of formula R-COO-S03H when t = 1. The acids of formula R-COO-S03H may be regarded as adducts of monocarboxylic acids R-COOH and of SO3 or alternatively as mixed anhydrides of monocarboxylic acids of formula R-COOH and of sulphuric acid. The monovalent hydrocarbon radical R which appears in the formula of the phosphonic acids (Formula Removed) and in the formula of the acids R-(COO) t-SO3H is chosen, as indicated above, from acyclic monovalent C1 to C16 hydrocarbon radicals and cyclic monovalent hydrocarbon radicals which contain 4 to 12 cyclic carbon atoms and which are optionally substituted by acyclic monovalent C1 to C16 hydrocarbon radicals. Thus, the radical R of acyclic type may be in particular a linear or branched C1 to C16 alkyl radical, for example such as methyl, ethyl, propyl, butyl, hexyl, heptyl, octyl, decyl, dodecyl or alternatively tetradecyl. The radical R of cyclic type may be in particular a C4 to C12 cycloalkyl radical and more particularly a C5 to C8 cycloalkyl radical, such as cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl, or else a monovalent aromatic radical which contains 6 cyclic carbon atoms and which may optionally be substituted by a linear or branched C1 to C16 alkyl radical, such as, for example, a phenyl, tolyl, decylphenyl, dodecylphenyl or tetradecylphenyl radical. Examples of sulphonic acids of formula R-S03H which may be employed in the process according to the invention are such as me thane sulphonic acid, ethanesulphonic acid, propanesulphonic acid, benzenesulphonic acid, toluenesulphonic acid, decylbenzenesulphonic acid, dodecylbenzenesulphonic acid and tetradecylbenzenesulphonic acid. Examples of phosphonic acids of formula (Formula Removed) which may be employed in the process according to the invention are such as methylphosphonic acid, ethylphosphonic acid, propylphosphonic acid, butylphosphonic acid and phenylphosphonic acid. Mention may be made, as acids of formula R-COO-SO3H, of the acids CH3-COO-SO3H and CH3-CH2-COO-S03H, which are adducts of S03 with acetic acid and propionic acid respectively. The olefinic polymers carrying epoxy or COOH functional groups, at least one of which is incorporated in the bitumen or mixture of bitumens in order to form the bitumen/polymer component, are advantageously composed of olefinic copolymers containing, by weight, x% of units derived from ethylene or propylene, y% of units derived from one or more monomers A of formula CH2 = C, z% of units derived from at least one monomer B of formula R3-CH = c and v% of units derived from one or more monomers C differing from the monomers A and B, with, in these formulae, R1 denoting H, CH3 or C2H5, R2 denoting a -COOR5, -OR5 or -OOCR6 radical, with R5 denoting a C1 to C10 and preferably C1 to C6 alkyl radical and R6 denoting H or a C1 to C3 alkyl radical, R3 denoting H, COOH or COOR5, R5 having the abovementioned definition, and R4 denoting a -COOH, (Formula Removed) y, z and v being numbers such that 40 In the abovementioned copolymers, x, y, z and v are preferably such that 50 The monomers A of formula CH-, = CR1 which are chosen in particular from vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl ethers CH2=CH-O-R5, where Rs is a C1 to C10 and preferably C1 to C6 alkyl radical such as methyl, ethyl, propyl or butyl, and alkyl acrylates and methacrylates of formula CH2=CH-COORS and CH2 = C - COOR5 respectively, where R5 has the meaning given above. The monomers B of formula (Formula Removed)which provide units in the olefinic copolymer, are chosen in particular from maleic acid and its anhydride, acrylic acid, methacrylic acid, alkyl hydrogen maleates of formula HOOC-CH=CH-COOR7 where R7 is a C1 to C6 alkyl radical such as methyl, ethyl, propyl or butyl, glycidyl acrylates and methacrylates of formula (Formula Removed) respectively, vinyl alcohol and vinyl glycidyl ether of formula (Formula Removed) The monomers C, the presence of which in the olefinic copolymer is optional, are monomers which can be polymerized by a radical route which differ from the monomers A and B, like, for example, CO, S02 and acrylonitrile. In particular, the olefinic copolymers carrying epoxy or COOH functional groups are chosen from: (a) random copolymers of ethylene and of a monomer B chosen from acrylic acid, methacrylic acid, maleic acid or its anhydride, glycidyl acrylate and glycidyl methacrylate, which contain, by weight, 80% to 99.7%, and preferably 85% to 99.5%, of ethylene; (b) random terpolymers of ethylene, of a monomer A chosen from vinyl acetate and alkyl acrylates or methacrylates containing a C1 to C6 alkyl residue, such as methyl, ethyl, propyl, butyl or hexyl, and of a monomer B, chosen from acrylic acid, methacrylic acid, maleic acid or its anhydride, glycidyl acrylate and glycidyl methacrylate, which contain, by weight, 0.5% to 40% of units derived from the monomer A and 0.5% to 15% of units derived from the monomer B, the remainder being formed by units derived from ethylene; and (c) the copolymers resulting from the grafting of a monomer B, chosen from acrylic acid, methacrylic acid, maleic acid or its anhydride, glycidyl acrylate and glycidyl methacrylate, onto a substrate consisting of a polymer chosen from polyethylenes, especially low density polyethylenes, polypropylenes and random copolymers of ethylene and of vinyl acetate or of ethylene and of alkyl acrylate or methacrylate containing a C1 to C6 alkyl residue, such as methyl, ethyl, propyl, butyl or hexyl, which contain, by weight, 40% to 99.7%, and preferably 50% to 99%, of ethylene, the said graft copolymers containing, by weight, 0.5% to 15% of grafted units originating from the monomer B. Olefinic copolymers chosen from the following are particularly preferred: (i) random terpolymers of ethylene, of alkyl acrylate or methacrylate containing a C1 to C6 alkyl residue, such as methyl, ethyl or butyl, and of maleic anhydride, which contain, by weight, 0.5% to 40% of units derived from alkyl acrylate or methacrylate and 0.5% to 15% of units derived from maleic anhydride, the remainder being formed by units derived from ethylene; (ii) random terpolymers of ethylene, of alkyl acrylate or methacrylate containing a C1 to C6 alkyl residue, such as methyl, ethyl or butyl, and of glycidyl acrylate or methacrylate, which contain, by weight, 0.5% to 40% of units derived from alkyl acrylate or methacrylate and 0.5% to 15% of units derived from glycidyl acrylate or methacrylate, the remainder being formed by units derived from ethylene; (iii) maleic anhydride-grafted low density polyethylenes and maleic anhydride-grafted polypropylenes, which contain, by weight, 0.5% to 15% of grafted units derived from maleic anhydride; (iv) glycidyl acrylate or methacrylate-grafted low density polyethylenes and glycidyl acrylate or methacrylate-grafted polypropylenes, which contain, by weight, 0.5% to 15% of grafted units resulting from the glycidyl derivative. The olefinic copolymers carrying epoxy or COOH functional groups, employed to produce the bitumen/ polymer component, advantageously have molecular masses such that the melt index of the said copolymers, determined according to ASTM Standard D 1238 (test carried out at 190°C under a 2.16 kg load) has a value, expressed in grams per 10 minutes, of between 0.3 and 3000 and preferably between 0.5 and 900. The bitumen, or mixture of bitumens, which is employed for the implementation of the process according to the invention is advantageously chosen from the various bitumens which have a kinematic viscosity at 100°C of between 0.5 x 10-4 m2/s and 3 x 1o-2 m2/s and preferably between 1 x 1o-4 m2/s and 2 x 1o-2 m2/s. These bitumens may be direct distillation or vacuum distillation bitumens or else blown or semiblown bitumens, propane or pentane deasphalting residues, viscosity breaking residues, indeed even some petroleum cuts or mixtures of bitumens and of vacuum distillates or alternatively mixtures of at least two of the products which have just been listed. Besides a kinematic viscosity included within the abovementioned ranges, the bitumen or mixture of bitumens employed in the process according to the invention advantageously has a penetrability at 25°C, defined according to NF Standard T 66004, of between 5 and 800 and preferably between 10 and 400. In addition to the olefinic polymer functionalized by epoxy or COOH groups, the bitumen/ polymer component, which is treated with the acidic adjuvant, may also contain one or more additional polymers other than the said functionalized olefinic polymer, the said additional polymer or polymers being in particular elastomers and especially sulphur-crosslinkable elastomers. These elastomers are advantageously chosen from random or block copolymers of styrene and of a conjugated diene such as butadiene, isoprene, chloroprene, carboxylated butadiene and carboxylated isoprene, and more particularly consist of one or more copolymers chosen from block copolymers, with or without a random hinge, of styrene and butadiene, of styrene and isoprene, of styrene and chloroprene, of styrene and carboxylated butadiene or alternatively of styrene and carboxylated isoprene. The copolymer of styrene and of conjugated diene, and in particular each of the abovementioned copolymers, advantageously has a styrene weight content ranging from 5% to 50%. The weight-average molecular mass of the copolymer of styrene and of conjugated diene, and especially that of the abovementioned copolymers, may be, for example, between 10,000 and 600,000 daltons and is preferably between 30,000 and 400,000 daltons. The copolymer of styrene and of conjugated diene is preferably chosen from di- or triblock copolymers of styrene and butadiene, of styrene and isoprene, of styrene and carboxylated butadiene or alternatively of styrene and carboxylated isoprene which have styrene contents and weight-average molecular masses that lie within the ranges defined above. The quantity of the additional polymer or polymers and in particular the quantity of the sulphur-crosslinkable elastomer or elastomers in the bitumen/ polymer component may be between 0.3% and 20% and preferably between 0.5% and 10% of the weight of the bitumen of the said component. The bitumen/polymer component, which contains a sulphur-crosslinkable elastomer in addition to the olefinic polymer functionalized by epoxy or COOH groups, may advantageously be subjected to crosslinking under the effect of a sulphur-donor coupling agent, in order to form a crosslinked bitumen/polymer component which constitutes the bitumen/polymer component subjected to treatment by the acidic adjuvant. The sulphur-donor coupling agent which is employed in the preparation of the crosslinked bitumen/polymer component according to the invention may consist of a product chosen from the group made up of elemental sulphur, hydrocarbyl polysulphides, sulphur donor vulcanization accelerators, or mixtures of such products with each other and/or with vulcanization accelerators which are not sulphur donors. In particular, the sulphur donor coupling agent is chosen from the products M, which contain, by weight, from 0% to 100% of a component CA composed of one or more sulphur-donor vulcanization accelerators and from 100% to 0% of a component CB composed of one or more vulcanizing agents chosen from elemental sulphur and hydrocarbyl polysulphides, and the products N, which contain a component CC composed of one or more vulcanization accelerators which are not sulphur donors and a product M in a weight ratio of the component CC to the product M ranging from 0.01 to 1 and preferably from 0.05 to 0.5. The elemental sulphur capable of being employed for constituting, partially or entirely, the coupling agent is advantageously sulphur in flower form and preferably sulphur crystallized in the orthorhombic form and known by the name of alpha sulphur. The hydrocarbyl polysulphides capable of being employed to form a proportion or all of the coupling agent may be chosen from those defined in reference FR-A-2,528,439 and corresponding to the general formula R8-(S)m-(-R9-(S)m-)w-R10/ in which each of R8 and R10 denotes a saturated or unsaturated, monovalent C1 to C20 hydrocarbon radical, or both are joined together to form a saturated or unsaturated, divalent Cx to C20 hydrocarbon radical forming a ring with the other groups of atoms associated in the formula, R9 is a saturated or unsaturated, divalent C1 to C20 hydrocarbon radical, the -(s)m- groups denote divalent groups, each made up of m sulphur atoms, the values m being able to differ from one of the said groups to another and denoting integers ranging from 1 to 6 with at least one of the values of m equal to or greater than 2 and w denotes an integer assuming values from zero to 10. Preferred polysulphides correspond to the formula R11-(S)p-R11 in which R11 denotes a C6 to C16 alkyl radical, for example hexyl, octyl, dodecyl, tert-dodecyl, hexadecyl, nonyl or decyl, and -(S)p- denotes a divalent group made up of a chain sequence of p sulphur atoms, p being an integer ranging from 2 to 5. When the coupling agent contains a sulphur-donor vulcanization accelerator, the latter may be chosen in particular from the thiuram polysulphides of formula (Formula Removed) in which each of the symbols R12, which are identical or different, denotes a C1 to C12 and preferably C1 to C8 hydrocarbon radical, especially an alkyl, cycloalkyl or aryl radical, or else two R12 radicals attached to the same nitrogen atom are bonded together to form a C2 to C8 divalent hydrocarbon radical and u is a number ranging from 2 to 8. As examples of such vulcanization accelerators, there may be mentioned especially the compounds: dipentamethylenethiuram disulphide, dipentamethylenethiuram tetrasulphide, dipentamethylenethiuram hexasulphide, tetrabutylthiuram disulphide, tetraethylthiuram disulphide and tetramethylthiuram disulphide. As other examples of sulphur-donor vulcanization accelerators there may also be mentioned alkylphenol disulphides and disulphides such as morpholine disulphide and N,N' -caprolactam disulphide. Vulcanization accelerators which are not sulphur-donors and which can be employed for forming the component CC of the coupling agents of the product N type may be sulphur compounds chosen especially from mercaptobenzothiazole and its derivatives, especially benzothiazole metal thiolates and above all benzothiazolesulphenamides, dithiocarbamates of formula (Formula Removed) Y, in which the symbols R12, which are identical or different, have the meaning given above, Y denotes a metal and f denotes the valency of Y, and thiuram monosulphides of formula (Formula Removed) in which the symbols R12 have the meaning given above . Examples of vulcanization accelerators of the mercaptobenzothiazole type may be such as mercaptobenzothiazole, benzothiazole thiolate of a metal such as zinc, sodium or copper, benzothiazyl disulphide, 2 -benzothiazolepentamethylenesulphenamide , 2 -benzothiazolethiosulphenamide , 2-benzothiazoledihydrocarbylsulphenamides in the case of which the hydrocarbyl radical is an ethyl, isopropyl, tert-butyl or cyclohexyl radical, and N-oxydiethylene-2-benzothiazolesulphenamide . Among the vulcanization accelerators of the dithiocarbamate type of the abovementioned formula, there may be mentioned the compounds which are dimethyldithio-carbamates of metals such as copper, zinc, lead, bismuth and selenium, diethyldithio-carbamates of metals such as cadmium and zinc, diamyldithiocarbamates of metals such as cadmium, zinc and lead, and lead or zinc pentamethylenedithio-carbamate. By way of examples of thiuram monosulphides which have the formula given above, there may be mentioned compounds such as dipentamethylenethiuram monosulphide, tetramethylthiuram monosulphide, tetraethylthiuram monosulphide and tetrabutylthiuram monosulphide. Other vulcanization accelerators which are not sulphur donors and which do not belong to the classes defined above may also be employed. Such vulcanization accelerators may be such as 1,3-diphenylguanidine, di-ortho-tolylguanidine and zinc oxide, the latter compound being employed optionally in the presence of fatty acid. For further details on the sulphur-donor vulcanization accelerators and those which are not sulphur donors that can be employed in the constitution of the coupling agent, reference may be made to citations EP-A-0,360,656 and EP-A-0,409, 683 , the content of which is incorporated in the present description by reference, as is the content of citation FR-A-2,528,439. As follows from its composition, as indicated above, the coupling agent may be of the single-component or of the multicotnponent type, it being possible for the coupling agent of the multicomponent type to be formed before it is employed or alternatively produced in situ in the mixture in which it must be present. The coupling agent of the preformed multicomponent type or of the single-component type or the components of the coupling agent of the multicomponent type formed in situ may be used as they are, for example in the molten state, or else as a mixture, for example in solution or in suspension, with a diluent, for example a hydrocarbon compound. The coupling agent is employed in a quantity capable of providing a quantity of free sulphur representing 0.1% to 20% and preferably 0.5% to 10% of the weight of sulphur-crosslinkable elastomer in the bitumen/polymer component which is subjected to crosslinking by the coupling agent. The bitumen/polymer component which is subjected to the action of the acidic adjuvant is prepared by bringing the olefinic polymer carrying epoxy or carboxyl functional groups and, if appropriate, the additional polymer or polymers, for example sulphur-crosslinkable elastomer, into contact with the bitumen or mixture of bitumens, in proportions chosen within the ranges defined above, the operation being carried out at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, and with stirring, for a period of time of at least 10 minutes, generally of the order of a few tens of minutes to a few hours and, for example, from 10 minutes to 8 hours and more particularly from 10 minutes to 5 hours, in order to form a reaction product constituting the bitumen/polymer component. When an additional polymer, for example a sulphur-crosslinkable elastomer is employed in addition to the olefinic polymer functional!zed by epoxy or COOH groups, the said additional polymer may be brought into contact with the bitumen or mixture of bitumens before or after the functionalized olefinic polymer or even at the same time as the latter. When it is desired to produce a crosslinked bitumen/polymer component, a non-crosslinked butumen/polymer component is first of all formed, the operation being carried out as indicated above, which is composed of a bitumen or mixture of bitumens containing at least one olefinic polymer carrying epoxy or COOH functional groups and at least one sulphur-crosslinkable elastomer, for example a block copolymer of styrene and of a conjugated diene, then the sulphur-donor coupling agent is incorporated in the said non-crosslinked bitumen/polymer component, in an appropriate quantity chosen within the ranges defined above for the said quantity, and the whole mixture is maintained with stirring at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, which are optionally identical to the temperatures for the preparation of the non-crosslinked bitumen/polymer component, for a period of time of at least 10 minutes and generally ranging from 10 minutes to 5 hours, more particularly from 30 minutes to 3 hours, in order to form a reaction mass constituting the sulphur-crosslinked bitumen/polymer component. The non-crosslinked or crosslinked bitumen/polymer component is treated with the acidic adjuvant by incorporating the said acidic adjuvant, in an appropriate quantity chosen within the ranges defined above for the said quantity, in the said bitumen/polymer component maintained at temperatures of between 100 °C and 230°C, more particularly between 120°C and 190°C, and with stirring, and by then maintaining the whole mixture at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, and with stirring, for a period of time of at least 10 minutes and in particular from 10 minutes to 5 hours, more particularly from 30 minutes to 4 hours, in order to produce the bitumen/polymer composition of very low temperature susceptibility. During its constitution, the bitumen/polymer component of the non-crosslinked type or of the sulphur-crosslinked type, which is then subjected to the action of the acidic adjuvant, may further have added to it from 1% to 40%, and more particularly from 2% to 30%, by weight of the bitumen, of a fluxing agent which may consist, in particular, of a hydrocarbon oil which has an atmospheric pressure distillation range, determined according to ASTM Standard D 86-67, of between 100°C and 600°C and lying more especially between 150°C and 400°C. This hydrocarbon oil, which may be especially a petroleum cut of aromatic nature, a petroleum cut of naphtheno-aromatic nature, a petroleum cut of naphtheno-paraffinic nature, a petroleum cut of paraffinic nature, a coal oil or else an oil of plant origin, is sufficiently "heavy" to limit the evaporation at the time of its addition to the bitumen and, at the same time, sufficiently "light" to be removed as much as possible after the bitumen/polymer composition containing it has been spread, so as to regain the same mechanical properties which the bitumen/polymer composition prepared without employing any fluxing agent would have exhibited after hot spreading. The fluxing agent may be added to the reaction mixture, which is formed' from the bitumen, the sulphur-crosslinkable elastomer and the sulphur-donor coupling agent, at any time in the constitution of the said reaction mixture, the quantity of fluxing agent being chosen within the ranges defined above, in order to be compatible with the desired final use on the work site. The reaction mixture based on bitumen or mixture of bitumens, on olefinic polymer carrying epoxy or COOH functional groups and, when they are used, on additional polymer, such as, for example, sulphur-crosslinkable elastomer, and sulphur-donor coupling agent, which gives rise to the non-crosslinked or crosslinked bitumen/polymer component which is then treated with the acidic adjuvant, may also contain one or more additives capable of reacting with the epoxy or COOH groups of the functionalized olefinic polymer. These reactive additives may be, in particular, primary or secondary amines, especially polyamines, alcohols, especially polyols, acids, especially polyacids, or else metal salts. Reactive additives of the amine type are, for example, aromatic diamines such as 1,4-diaminobenzene, 2,4-diaminotoluene, diaminonaphthalene, bis(4-amino- phenyl) sulphone, bis(4-aminophenyl) ether, bis(4-aminophenyl)methane, aliphatic or cycloaliphatic diamines such as those of formula H2N-R13-NH2 where R13 denotes a C2 to C12 alkylene or C6 to C12 cycloalkylene radical, for example ethylenediamine, diaminopropane, diamino-butane, diaminohexane, diaminooctane, diaminodecane, diaminododecane, diaminocyclohexane, diaminocyclooctane, diaminocyclododecane, polyethylenepolyamines or poly-propylenepolyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine or dipropylenetriamine or else fatty amines or polyandries, that is to say amines or polyamines containing a C12 to C18 alkyl or alkenyl radical bonded to the nitrogen atom of an amine group. Reactive additives of the alcohol type are, in particular, polyols such as diols or triols and especially diols of formula HO-R14-OH, where R14 denotes a hydrocarbon radical, especially a C2 to C18 alkylene, C6 to C8 arylene and C6 to C8 cycloalkylene radical, and polyetherdiols of formula HO [CqH2qO] rH where q is a number ranging from 2 to 6 and especially equal to 2 or 3 and r is a number at least equal to 2 and ranging, for example, from 2 to 20. Examples of such polyols are such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, hexanediol, octanediol and polyhydroxylated polybutadiene. Reactive additives of the acid type are, in particular, polyacids of formula HOOC-R14-COOH, where R14 has the meaning given above. Examples of such polyacids are such as phthalic acid, terephthalic acid, malonic acid, succinic acid, adipic acid, glutaric acid and polycarboxylated polybutadiene. Reactive additives of the metal salt type are, in particular, compounds such as hydroxides, oxides, alcoholates, carboxylates like formates and acetates, methoxides, ethoxides, nitrites, carbonates and bicarbonates of metals of groups I, II, III and VIII of the Periodic Table of the Elements, especially Na, K, Li, Mg, Ca, Cd, Zn, Ba, Al and Fe. The quantity of the reactive additive or of the reactive additives which is incorporated in the reaction mixture giving rise to the bitumen/polymer components may range from 0.01% to 10% and, more particularly, from 0.05% to 5% of the weight of bitumen present in the said reaction mixture. Besides the reactive additives and the fluxing agent, it is also possible to incorporate in the reaction mixture giving rise to the bitumen/polymer components, at any time in the constitution of the said reaction mixture, additives which are conventionally employed in bitumen/polymer compositions, such as promoters of adhesion of the bitumen/polymer composition to the mineral surfaces or else fillers such as talc, carbon black or worn tyres reduced to fine powder. In one form of implementation of the preparation of the bitumen/polymer component, employing a hydrocarbon oil as defined above as fluxing agent, the olefinic polymer carrying epoxy or COOH functional groups and, if they are present, the additional polymer and the sulphur-donor coupling agent are incorporated in the bitumen or mixture of bitumens in the form of a mother solution of these products in the hydrocarbon oil constituting the fluxing agent. The mother solution is prepared by bringing into contact the ingredients of which it is composed, namely hydrocarbon oil used as solvent, olefinic polymer containing epoxy or COOH groups and, if present, an additional polymer, such as sulphur-crosslinkable elastomer, and sulphur-donor coupling agent, with stirring, at temperatures of between 10°C and 170°C and more particularly between 40°C and 120°C, for a sufficient period of time, for example of between 10 minutes and 2 hours, to obtain complete dissolution of the polymeric ingredients and of the coupling agent in the hydrocarbon oil. The respective concentrations of the olefinic polymer containing epoxy or COOH groups, of the additional polymer and of the coupling agent in the mother solution may vary quite widely, especially as a function of the nature of the hydrocarbon oil employed for dissolving the said polymer ingredients and the coupling agent. Thus, the respective quantities of functionalized olefinic polymer, of additional polymer and of coupling agent may advantageously represent 1% to 20%, 5% to 30% and 0.005% to 6% of the weight of the hydrocarbon oil. To prepare the bitumen/polymer components by making use of the mother solution technique, the mother solution containing the functionalized olefinic polymer and, if employed, the additional polymer and the sulphur-donor coupling agent is mixed with the bitumen or mixture of bitumens, the operation being carried out at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, and with stirring, this being done, for example, by incorporating the mother solution into the bitumen kept stirring at temperatures of between 100°C and 230°C and more particularly between 120°C and 190°C, and the resulting mixture is then kept stirring at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, for example at the temperatures employed for producing the mixture of the mother solution with the bitumen, for a period of time of at least 10 minutes and generally ranging from 10 minutes to 2 hours, to form a reaction product constituting the bitumen/polymer component. The quantity of mother solution which is mixed with the bitumen or mixture of bitumens is chosen to yield the desired quantities, relative to the bitumen, of olefinic polymer containing epoxy or COOH groups, of additional polymer and of sulphur-donor coupling agent, the said quantities being within the ranges defined above. The bitumen/polymer compositions of very low temperature susceptibility obtained by the process according to the invention may be employed as they are or else diluted with variable proportions of a bitumen or mixture of bitumens or of a composition according to the invention which has different characteristics, in order to constitute bitumen/polymer binders which have a chosen content of crosslinked elastomer which may be either equal to (undiluted composition) or else lower than (diluted composition) the content of crosslinked elastomer in the corresponding initial bitumen/polymer compositions. The dilution of the bitumen/polymer compositions according to the invention with the bitumen or mixture of bitumens or with a composition according to the invention of different characteristics may be carried out either directly following the preparation of the said compositions, when a virtually immediate use of the resulting bitumen/polymer binders is required, or else alternatively after a more or less extended period of storage of the bitumen/polymer compositions, when a delayed use of the resulting bitumen/polymer binders is envisaged. The bitumen or mixture of bitumens employed for the dilution of a bitumen/polymer composition according to the invention may be chosen from the bitumens defined above as being suitable for the preparation of the bitumen/polymer compositions. If appropriate, the bitumen or mixture of bitumens employed for the dilution may itself have been pretreated with an acidic adjuvant according to the invention. The dilution of a bitumen/polymer composition with a bitumen or mixture of bitumens or with a second composition according to the invention with a lower content of polymer (functionalized olefinic polymer and, if present, additional polymer), in order to form a bitumen/polymer binder with a chosen content of polymer which is lower than that in the bitumen/polymer composition to be diluted is generally carried out by bringing into contact, with stirring and at temperatures of between 100°C and 230°C and more particularly between 120°C and 190°C, suitable proportions of the bitumen/polymer composition to be diluted and of bitumen or mixture of bitumens or of second bitumen/polymer composition according to the invention. The bitumen/polymer binders consisting of the bitumen/polymer compositions according to the invention or resulting from the dilution of the said compositions with a bitumen or mixture of bitumens or with another bitumen/polymer composition according to the invention, as far as the desired content of polymer (s) in the said binders, can be applied, directly or after conversion into aqueous emulsion, to the production of road surfacings of the surface coating type, ' to the production of bituminous mixes which are put in place with heating or cold, or else to the production of watertight facings. The invention is illustrated by the following examples, given without any limitation being implied. In these examples, the quantities and percentages are expressed by weight, except where otherwise indicated. In addition, the rheological and mechanical characteristics of the bitumens or of the bitumen/ polymer compositions to which reference is made in the said examples, namely penetrability, ring-and-ball softening point and Pfeiffer's number (PN), are those defined above. EXAMPLES 1 TO 9 A control bituminous composition (Example 1) or control bitumen/polymer compositions (Examples 2, 4, 6 and 8) and bitumen/polymer compositions according to the invention (Examples 3, 5, 7 and 9) were prepared in order to evaluate them and to compare the physicomechanical characteristics. The operation was carried out under the following conditions: Example 1 (control): Preparation of a bituminous composition composed of a bitumen modified by an acidic adjuvant. 1000 parts of a bitumen having a penetrability, determined according to the method of NF Standard T 66004, in the range 70/100 and 5 parts of 75% phosphoric acid were introduced into a reactor maintained at 175°C and with stirring. The contents of the reactor were then maintained at 175°C with stirring for a period of time equal to 3 hours in order to produce the bituminous composition. Example 2 (control): Preparation of a bitumen/polymer composition not treated with an acidic adjuvant. 980 parts of a bitumen identical to that employed in Example 1 and 20 parts of an ethylene/methyl acrylate/glycidyl methacrylate ter-polymer containing 24% of methyl acrylate and 8% of glycidyl methacrylate and possessing a melt index, determined according to ASTM Standard D 1238, with a value equal to 6 g per 10 minutes were introduced into a reactor maintained at 175°C and with stirring. After mixing for 2.5 hours with stirring at 175°C, a homogeneous mass constituting the bitumen/polymer composition was obtained. Example 3 (according to the invention: Preparation of a bitumen/polymer composition by treating a bitumen/polymer component not crosslinked by an acidic adjuvant. 980 parts of a bitumen identical to that employed in Example 1 and 20 parts of the terpolymer employed in Example 2 were introduced into a reactor maintained at 175°C and with stirring and the whole mixture was maintained with stirring at 175°C for 2.5 hours. 5 parts of 75% phosphoric acid were then added to the contents of the reactor and the whole mixture was then maintained at 175°C with stirring for 3 hours, in order to form the bitumen/polymer composition. Example 4 (control): Preparation of a non-crosslinked bitumen/polymer composition which includes an elastomer, the composition not being treated with acidic adjuvant. 955 parts of a bitumen identical to that employed in Example 1, then 30 parts of an elastomer composed of a triblock styrene/butadiene/styrene copolymer, having an average molecular mass of 150,000 daltons and containing 30% of styrene, and 15 parts of the terpolymer employed in Example 2 were introduced into a reactor maintained at 175°C and with stirring. The contents of the reactor were then maintained with stirring at 175°C for 2.5 hours in order to form the non-crosslinked bitumen/polymer composition. Example 5 (according to the invention): Preparation of a non-crosslinked bitumen/polymer composition which includes an elastomer, the composition being treated with an acidic adjuvant. By carrying out the preparation as described in Example 4, a non-crosslinked bitumen/polymer composition which includes an elastomer, known as bitumen/polymer component, was prepared. 4 parts of a polyphosphoric acid were then incorporated in the contents of the reactor and the reaction mixture thus formed was then maintained at 175°C with stirring for a period of time equal to 2.5 hours, in order to produce the bitumen/ polymer composition according to the invention. The polyphosphoric acid employed corresponded to the formula PnHn+203n+1, n being a number equal to approximately 3. Example 6 (control): Preparation of a non-crosslinked bitumen/polymer composition which is not treated with an acidic adjuvant. A bitumen/polymer composition was prepared, the preparation being carried out as described in Example 2, with the use, however, of a bitumen having a penetrability within the range 180/220. Example 7 (according to the invention): Preparation of a bitumen/polymer composition by treating a bitumen/polymer component with an acidic adjuvant. By carrying out the preparation as described in Example 6, a non-crosslinked bitumen/polymer composition, known as bitumen/polymer component, was prepared. 3 parts of methanesulphonic acid were incorporated in the contents of the reactor and then the whole mixture was maintained at 175°C, with stirring, for a period of time of 3 hours, in order to produce the bitumen/polymer composition according to the invention. Example 8 (control): Preparation of a crosslinked bitumen/polymer composition which is not treated with an acidic adjuvant. 960 parts of a bitumen identical to that employed in Example 6, then 30 parts of an elastomer composed of a diblock styrene/butadiene copolymer, having an average molecular mass of 100,000 daltons and a styrene content of 25%, and 10 parts of the terpolymer employed in Example 2 were introduced into a reactor maintained at 175°C and with stirring and the reaction mixture thus formed was maintained with stirring at 175°C for 2.5 hours. 0.8 part of sulphur was then added to the contents of the reactor and the whole mixture was maintained with stirring at 175°C for 3 hours, in order to form a crosslinked bitumen/polymer composition. Example 9 (according to the invention): Preparation of a crosslinked bitumen/polymer composition which is treated with an acidic adjuvant. By carrying out the preparation as described in Example 8, a sulphur-crosslinked bitumen/polymer composition, known as crosslinked bitumen/polymer component, was prepared. 5 parts of 98% sulphuric acid were then incorporated in the contents of the reactor and the reaction mixture thus formed was then maintained at 175°C and with stirring for a period of time of 2.5 hours, in order to produce the crosslinked bitumen/polymer composition treated with an acidic adjuvant according to the invention. The following characteristics were determined for each of the compositions obtained as shown in Examples 1 to 9: - penetrability at 25°C (Pen.), ring-and-ball softening temperature (RBT), Pfeiffer's number (PN). The results obtained are collected in the table below. In this table, the abbreviations BT1, BT2, TPO, SBS and SB have the following meanings: BT1: unmodified bitumen with a penetrability in the range 70/100; BT2: unmodified bitumen with a penetrability in the range 180/220; TPO: ethylene/methyl acrylate/glycidyl meth-crylate terpolymer employed in Examples 2, 3, 4, 5, 6, 7, 8 and 9; SBS: triblock styrene/butadiene/styrene copolymer employed in Examples 4 and 5; SB: diblock styrene/butadiene copolymer employed in Examples 8 and 9. The TPO, SBS and SB contents of the compositions are expressed as percentages by weight of the overall quantities of bitumen and polymer(s). The sulphur content is expressed as % of the weight of the bitumen. Table (Table Removed) In the light of the characteristics collected in the table, it is apparent that: the incorporation of a functionalized. olefinic polymer according to the invention, for example olefinic polymer carrying epoxy groups, in a bitumen improves the physical properties of the said bitumen (increase in the RBT value and in Pfeiffer's number), as emerges from the comparison of Example 2 with BT1 or of Example 6 with BT2 ; the addition of an acidic adjuvant according to the invention to a bitumen also reinforces the consistency of the bitumen (increase in the RBT value and in Pfeiffer's number), as emerges from the comparison of Example 1 with BT1; the addition of an acidic adjuvant according to the invention to a bitumen modified by a functionalized olefinic polymer according to the invention, for example olefinic polymer carrying epoxy groups, results in an increased reinforcement of the physical properties of the composition (greater increase in the RBT value and in Pfeiffer's number than in the preceding case) by a phenomenon of synergy between the two modifying agents, namely functionalized olefinic polymer and acidic adjuvant, as emerges from the comparison of the results from Example 3 with the results of Control Examples 1 and 2; the abovementioned synergy effect is magnified when the bitumen/polymer component treated with the acidic adjuvant contains an elastomer, in addition to the functionalized olefinic polymer, as may be seen in the comparison of the results of Example 5 according to the invention with the results of Control Example 4; the magnified synergy effect is even more marked if the bitumen/polymer composition containing an elastomer, which is subjected to treatment by the acidic adjuvant, has been subjected to crosslinking with sulphur prior to the said treatment, as emerges from the comparison of the results of Example 9 according to the invention with the results of Control Example 8. We Claims 1. Process for the preparation of bitumen/polymer compositions exhibiting, inter alia, a very low temperature susceptibility, in which a bitumen or mixture of bitumens is brought into contact, the operation being carried out at temperatures of between 100°C and 230°C and with stirring, for a period of time of at least 10 minutes, with 0.01% to 20%, calculated by weight of the bitumen of mixture of bitumens, of at least one olefinic polymer carrying epoxy or COOH functional groups, in order to form a reaction product known as bitumen/polymer component, the said process being characterized in that 0.005% to 6%, by weight of the bitumen or mixture of bitumens, of an acidic adjuvant is incorporated in the bitumen/polymer component, which is maintained at temperatures of between 100°C and 230°C and with stirring, and the reaction mixture thus formed is maintained at temperatures of between 100°C and 230°C and with stirring for a period of time of at least 10 minutes in order to produce the bitumen/polymer composition, the said acidic adjuvant being composed of one or more compounds chosen from the group formed by phosphoric acids, boric acids, sulphuric acid, the anhydrides of the said acids, chlorosulphuric acid, polyphosphoric acids, phosphonic acids of formula (Formula Removed) and acids of formula R- (COO) t-SO3H with, in the said formulae, t taking the value zero or one and R denoting a monovalent hydrocarbon radical chosen from the group composed of acyclic monovalent C1 to C16 hydrocarbon radicals and cyclic monovalent hydrocarbon radicals containing 4 to 12 cyclic carbon atoms and optionally substituted by acyclic monovalent C1 to C16 hydrocarbon radicals. 2. Process according to Claim l, characterized in that the total amount of acidic adjuvant incorporated in the bitumen/polymer component represents 0.01% to 3% by weight of the bitumen or mixture of bitumens. 3. Process according to Claim 1 or 2, characterized in that the acidic adjuvant is chosen from H3P04, P205, H3B03/ B203/ H2S04/ S03, HS03Cl, polyphosphoric acids, mixtures of at least one polyphosphoric acid and of sulphuric acid, mixtures of at least one polyposphoric acid and of at least one acid R-(COO) t-S03H, mixtures of sulphuric acid and of at least one acid R-(COO)t-S03H and mixtures of sulphuric acid with at least one polyphosphoric acid and at least one acid R-(COO)t-SO3H. 4. Process according to Claim 3, characterized in that the acidic adjuvant consists of a combination composed, by weight, of 20% to 95% or more particularly of 40% to 90% of one or more polyphosphoric acids and of 80% to 5% and more particularly of 60% to 10% of sulphuric acid and/or of methanesulphonic acid. 5. Process according to one of Claims 1 to 4, characterized in that the polyphosphoric acids are compounds of formula PqHrOs in which q, r and s are positive numbers such that q > 2 and in particular ranging from 3 to 20 and 5q + r - 2s = 0, the said polyphosphoric acids having in particular the formula (Formula Removed) q having the meaning above. 6. Process according to one of Claims 1 to 3, characterized in that the acids R-(COO) t-S03H are such that R is a linear or branched C1 to C16 alkyl radical, a C4 to C12 and more particularly C5 to C8 cycloalkyl radical or alternatively a monovalent aromatic radical having 6 cyclic atoms and which may optionally be substituted by a linear or branched C1 to C16 alkyl radical. 7. Process according to one of Claims 1 to 6, characterized in that the quantity of olefinic polymer carrying epoxy or COOH functional groups brought into contact with the bitumen or mixture of bitumens, in order to form the bitumen/polymer component, represents 0.05% to 10% and more especially 0.1% to 6% of the weight of bitumen or mixture of bitumens. 8. Process according to one of Claims 1 to 7, characterized in that the olefinic polymer carrying epoxy or COOH groups is chosen from copolymers containing, by weight, x% of units derived from ethylene or propylene, y% of units derived from one or more monomers A of formula CH2 = C, z % of units derived from at least one monomer B of formula R3-CH = C and v% of units derived from one or more monomers C differing from the monomers A and B, with, in these formulae, R1 denoting H, CH3 or C2H,, R2 denoting a -COOR5, -OR5 or -OOCR6 radical, with R5 denoting a C1 to C10 and preferably C1 to C6 alkyl radical and R6 denoting H or a C1 to C3 alkyl radical, R3 denoting H, COOH or COOR5, R5 having the abovementioned definition, and R4 denoting a -COOH, -COO-CH2-<:h- or radical and x y v being numbers such that z with> 9. Process according to Claim 8, characterized in that, in the olefinic polymer containing epoxy or COOH groups, x, y, z and v are such that 50 100. 10. Process according to Claim 8 or 9, characterized in that the monomers A are chosen from vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl ethers CH2=CH-0-R5, alkyl acrylates of formula CH2 = CH-COOR5 and alkyl methacrylates of formula CH3 CH2 = Z - COOR5, R5 being a C1 to C10 and preferably C1 to C6 alkyl radical, in particular methyl, ethyl, propyl or butyl. 11. Process according to one of Claims 8 to 10, characterized in that the monomers B are chosen from maleic acid and its anhydride, acrylic acid, methacrylic acid, alkyl hydrogen maleates of formula HOOC-CH=CH-OOR7 where R7 is a C1 to C6 alkyl radical, glycidyl acrylate, glycidyl methacrylate and vinyl glycidyl ether. 12. Process according to one of Claims 8 to 11, characterized in that the monomers C are chosen from CO, S02 and acrylonitrile. 13. Process according to one of Claims 8 to 11, characterized in that the olefinic polymers containing epoxy or COOH groups are chosen from: (a) random copolymers of ethylene and of a monomer B chosen from acrylic acid, methacrylic acid, maleic acid or its anhydride, glycidyl acrylate and glycidyl methacrylate, which contain, by weight, 80% to 99.7%, and preferably 85% to 99.5%, of ethylene; (b) random terpolymers of ethylene, of a monomer A chosen from vinyl acetate and alkyl acrylates or methacrylates containing a C1 to C6 alkyl residue, such as methyl, ethyl, propyl, butyl or hexyl, and of a monomer B chosen from acrylic acid, methacrylic acid, maleic acid or its anhydride, glycidyl acrylate and glycidyl methacrylate, which contain, by weight, 0.5% to 40% of units derived from the monomer A and 0.5% to 15% of units derived from the monomer B, the remainder being formed by units derived from ethylene; and (c) the copolymers resulting from the grafting of a monomer B, chosen from acrylic acid, methacrylic acid, maleic acid or its anhydride, glycidyl acrylate and glycidyl methacrylate, onto a substrate consisting of a polymer chosen from polyethylenes, especially low density polyethylenes, polypropylenes and random copolymers of ethylene and of vinyl acetate or of ethylene and of alkyl acrylate or methacrylate containing a C1 to C6 alkyl residue, such as methyl, ethyl, propyl, butyl or hexyl, which contain, by weight, 40% to 99.7%. and preferably 50% to 99%, of ethylene, the said graft copolymers containing, by weight, 0.5% to 15% of grafted units originating from the monomer B. 14. Process according to Claim 13, characterized in that the olefinic polymers containing epoxy or COOH groups are chosen from: (i) random terpolymers of ethylene, of alkyl acrylate or methacrylate containing a C1 to C6 alkyl residue, such as methyl, ethyl or butyl, and of maleic anhydride, which contain, by weight, 0.5% to 40% of units derived from alkyl acrylate or methacrylate and 0.5% to 15% of units derived from maleic anhydride, the remainder being formed by units derived from ethylene; (ii) random terpolymers of ethylene, of alkyl acrylate or methacrylate containing a C1 to C6 alkyl residue, such as methyl, ethyl or butyl, and of glycidyl acrylate or methacrylate, which contain, by weight, 0.5% to 40% of units derived from alkyl acrylate or methacrylate and 0.5% to 15% of units derived from glycidyl acrylate or methacrylate, the remainder being formed by units derived from ethylene; (iii) maleic anhydride-grafted low density polyethylenes and maleic anhydride-grafted polypropylenes, which contain, by weight, 0.5% to 15% of grafted units derived from maleic anhydride; (iv) glycidyl acrylate or methacrylate-grafted low density polyethylenes and glycidyl acrylate or methacrylate-grafted polypropylenes, which contain, by weight, 0.5% to 15% of grafted units resulting from the glycidyl derivative. 15. Process according to one of Claims 8 to 14, characterized in that the olefinic polymers containing epoxy or COOH groups possess a melt index, determined according to ASTM Standard D 1238, with a value, expressed in grams per 10 minutes, of between 0.3 and 3000 and preferably between 0.5 and 900. 16. Process according to one of Claims 1 to 15, characterized that the bitumen or mixture of bitumens is chosen from bitumens having a kinematic viscosity at 100°C of between 0.5 x 10-4 m2/s and 3 x 10-2 m2/s and preferably between 1 x 10-4 m2/s and 2 x 10-2 m2/s. 17. Process according to Claim 16, characterized in that the bitumen or mixture of bitumens has a penetrability at 25°C, defined according to NF Standard T 66004, of between 5 and 800 and preferably between 10 and 400. 18. Process according to one of Claims 1 to 17, characterized in that one or more additional polymers, other than the olefinic polymers containing epoxy or COOH groups, is incorporated in the bitumen/polymer component during its preparation, the said additional polymer or polymers being in particular elastomers. 19. Process according to Claim 18, characterized in that the said elastomer or elastomers are sulphur- crosslinkable elastomers. 20. Process according to Claim 19, characterized in that the quantity of sulphur-crosslinkable elastomer represents between 0.3% and 20% and preferably between 0.5% and 10% of the weight of the bitumen or mixture of bitumens. 21. Process according to Claim 19 or 20, characterized in that the sulphur-crosslinkable elastomers are random or block copolymers of styrene and of a conjugated diene, the said diene in particular being such as butadiene, isoprene, chloroprene, carboxylated butadiene and carboxylated isoprene. 22. Process according to Claim 21, characterized in that the copolymers of styrene and of conjugated diene contain, by weight, 5% to 50% of styrene. 23. Process according to Claim 21 or 22, characterized in that the weight-average molecular mass of the copolymer of styrene and of conjugated diene is between 10,000 and 600,000 daltons and preferably between 30,000 and 400,000 daltons. 24. Process according to one of Claims 19 to 23, characterized in that the bitumen/polymer component, based on bitumen or mixture of bitumens, on olefinic polymer containing epoxy or COOH groups and on sulphur- crosslinkable elastomer, is subjected to crosslinking under the effect of a sulphur-donor coupling agent, in order to produce a crosslinked bitumen/polymer component. 25. Process according to Claim 24, characterized in that the sulphur-donor coupling agent is chosen from the group made up of elemental sulphur, hydrocarbyl poly- sulphides, sulphur-donor vulcanization accelerators, or mixtures of such products with each other and/or with vulcanization accelerators which are not sulphur donors. 26. Process according to Claim 25, characterized in that the sulphur-donor coupling agent is chosen from the products M, which contain, by weight, from 0% to 100% of a component CA composed of one or more sulphur-donor vulcanization accelerators and from 100% to 0% of a component CB composed of one or more vulcanizing agents chosen from elemental sulphur and hydrocarbyl poly-sulphides, and the products N, which contain a component CC composed of one or more vulcanization accelerators which are not sulphur donors and a product M in a weight ratio of the component CC to the product M ranging from 0.01 to 1 and preferably from 0.05 to 0.5. 27. Process according to one of Claims 24 to 26, characterized in that the coupling agent is employed in a quantity capable of providing a quantity of free sulphur representing 0.1% to 20% of the weight of sulphur-crosslinkable elastomer in the bitumen/polymer component subjected to crosslinking. 28. Process according to one of Claims 1 to 23, characterized in that the bitumen/polymer component is prepared by bringing the olefinic polymer or polymers carrying epoxy or COOH groups and, in the event of use, the additional polymer or polymers, for example sulphur- crosslinkable elastomer, into contact with the bitumen or mixture of bitumens, in the desired proportions, the operation being carried out at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, and with stirring, for a period of time of at least 10 minutes and more particularly from 10 minutes to 5 hours. 29. Process according to one of Claims 24 to 27, characterized in that the crosslinked bitumen/polymer component is prepared by bringing the olefinic polymer or polymers carrying epoxy or COOH groups and the sulphur-crosslinkable elastomer or elastomers into contact with the bitumen or mixture of bitumens, in the desired proportions, the operation being carried out at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, and with stirring, for a period of time of at least 10 minutes and more particularly from 10 minutes to 5 hours, the sulphur-donor coupling agent is then incorporated, in the desired quantity, in the product obtained, which product constitutes the non-crosslinked bitumen/polymer component, and the whole mixture is maintained with stirring at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, for a period of time of at least 10 minutes and, in particular, ranging from 10 minutes to 5 hours and more particularly from 10 minutes to 3 hours, in order to form a reaction mass constituting the crosslinked bitumen/polymer component. 30. Process according to Claim 28 or 29, characterized in that the acidic adjuvant is incorporated, in the desired quantity, in the non-crosslinked or crosslinked bitumen/polymer component, the incorporation being carried out at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, and with stirring, and then the whole mixture being maintained at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, and with stirring, for a period of time of at least 10 minutes and, in particular, from 10 minutes to- 5 hours and more particularly from 30 minutes to 4 hours, in order to produce the bitumen/polymer composition of very low temperature susceptability. 31. Process according to one of Claims 28 to 30, characterized in that, during its constitution, the crosslinked bitumen/polymer component or the non- crosslinked bitumen/polymer component, which is then subjected to the action of the acidic adjuvant, has added to it from 1% to 40%, and more particularly from 2% to 30%, by weight of the bitumen, of a fluxing agent. 32. Process according to Claim 31, characterized in that the fluxing agent is composed of a hydrocarbon oil which has an atmospheric pressure distillation range, determined according to ASTM Standard D 86-67, of between 100°C and 600°C and lying more especially between 150°C and 400°C, the said hydrocarbon oil being, in particular, a petroleum cut of aromatic nature, a petroleum cut of naphtheno-aromatic nature, a petroleum cut of naphtheno-paraffinic nature, a petroleum cut of paraffinic nature, a coal oil or else an oil of plant origin. 33. Process according to Claim 32, characterized in that the olefinic polymer or polymers carrying epoxy or COOH groups and, if they are present, the additional polymer or polymers and the coupling agent are incorporated in the bitumen or mixture of bitumens in the form of a mother solution of these products in the hydrocarbon oil constituting the fluxing agent. 34. Process according to Claim 33, characterized in that the mother solution contains, by weight of the hydrocarbon oil, 1% to 20% of the olefinic polymer or polymers containing epoxy or COOH groups and, in the event of use, 5% to 30% of the additional polymer or polymers and 0.005% to 6% of coupling agent. 35. Process according to Claim 33 or 34, characterized in that the mother solution is mixed with the bitumen or mixture of bituinens, the operation being carried out at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, and with stirring, and the resulting mixture is then kept stirring at temperatures of between 100°C and 230°C, more particularly between 120°C and 190°C, for a period of time of at least 10 minutes and, in particular, ranging from 10 minutes to 2 hours, to produce the bitumen/polymer component. 36. Process according to one of Claims 1 to 35, characterized in that, during its preparation, the bitumen/polymer component of the non-crosslinked type or of the crosslinked type, which is subjected to treatment with the acidic adjuvant, has added to it one or more additives capable of reacting with the functional groups of the olefinic polymer or polymers containing epoxy or COOH groups which it contains, the said reactive additives in particular being primary or secondary amines, especially polyamines, alcohols, and especially polyols, acids, and especially polyacids, or else metal salts, especially compounds of metals of groups I, II, III and VIII of the Periodic Table of the Elements. 37. Process according to Claim 36, characterized in that the quantity of reactive additive or of reactive additives which is incorporated in the reaction mixture giving rise to the bitumen/polymer component represents 0.01% to 10% and preferably 0.05% to 5% of the weight of the bitumen or mixture of bitumens. 38. Application of the bitumen/polymer compositions obtained by the process according to one of Claims 1 to 37 to the production of bitumen/polymer binders, the said binders being composed of the said compositions used as is or else being formed by dilution of the said bitumen/polymer compositions with a bitumen or mixture of bitumens or with a bitumen/polymer composition according to one of Claims 1 to 37 to an overall lower content of polymer, which bitumen/polymer binders can be employed in particular, directly or after conversion into aqueous emulsion, in the production of coatings, in particular road surfacings of the surface coating type, in the production of bituminous mixes which are put in place with heating or cold, or else in the production of watertight facings.

Documents:

1212-del-1997-abstract.pdf

1212-del-1997-claims.pdf

1212-del-1997-correspondence-others.pdf

1212-del-1997-correspondence-po.pdf

1212-del-1997-description (complete).pdf

1212-del-1997-form-1.pdf

1212-del-1997-form-13.pdf

1212-del-1997-form-19.pdf

1212-del-1997-form-2.pdf

1212-del-1997-form-3.pdf

1212-del-1997-form-4.pdf

1212-del-1997-form-6.pdf

1212-del-1997-gpa.pdf

1212-del-1997-petition-137.pdf

1212-del-1997-petition-138.pdf

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