WO2002057367A1

WO2002057367A1 - Modified bitumen composition

Info

Publication number: WO2002057367A1
Application number: PCT/FR2002/000249
Authority: WO
Inventors: Benoît ERNST; Laurent Martin; Jean-Jacques Flat; Evelyne Bonnet
Original assignee: Atofina
Priority date: 2001-01-22
Filing date: 2002-01-22
Publication date: 2002-07-25
Also published as: EP1354004A1; FR2819818B1; NO20033277D0; FR2819818A1; NO20033277L

Abstract

The invention concerns the use, as modifying agent for bitumen, a polymer containing free isocyanate functions and derived from the reaction of: (A) at least a polyisocyanate; (B) at least a polydiene polyol; and (C) at least an ethylene copolymer containing hydroxyl functions.

Description

MODIFIED BITUMEN COMPOSITIONS.

The present invention relates to bitumen compositions modified to exhibit improved properties at high temperatures, such as rut resistance, as well as increased resistance to fuels such as kerosene.

Bitumens find their primary use as a binder for road surfaces or as waterproofing materials; they are also used as shock absorbing underlayers:

- in the field of transport such as heavy weights, trunk mats, etc.

- in the building sector, such as underlayments for slabs, rubber or carpets. However, the mechanical properties of bitumens are very sensitive to temperature. They often become too rigid and fragile at winter temperatures, while they tend to creep at high temperatures (for example in summer). In addition, bitumens generally have a low resistance to fuels such as kerosene.

To overcome these drawbacks, numerous and varied additives have been proposed in the patent literature. Thus bitumens modified with rubber-type additives which may be latexes or powders of SBR (styrene butadiene rubber), NR (natural rubber) and SIR (styrene isoprene rubber) are described in the Japanese patents JP- B-4024034, JP-B-433120, JP-B-5423691 and JP-B-17618. The additives can also be thermoplastic elastomers of the block copolymer type such as SBS (styrene butadiene styrene), SIS (styrene-isoprene-styrene) and SEBS (hydrogenated SBS), EVTA (ethylene-vinyl acetate) and EEA (ethylene ethyl acrylate), as described in the Japanese patents JP-B-5913098, JP-B-6047403, JP-B-15642 and JP-A-63304059. Other modifiers for bitumens are thermoplastic epoxies, as described in Japanese patents JP-A-503543, JP-A-6116500 and JP-A-611633. We also know by US Patent US-A-5,331,028 combinations of glycidyl groups with styrenic elastomers and by American Patent ϋS-A-4,415,702 bituminous compositions comprising a moisture-crosslinkable additive, in particular on the basis of a polybutadiene prepolymer with hydroxyl endings, the latter solution however posing significant processing problems due to an increase in viscosity, which leads to poor workability. The present invention provides a particularly efficient modifier for bitumens, allowing the bitumen softening point to be increased and consequently allowing the temperature of use of the latter to be increased towards high temperatures. Road surfaces made with this bituminous binder therefore behave particularly well in high heat. The irreversible deformations by creep of the surface under the action of road traffic are reduced, that is to say that the resistance to rutting of a road surface thus will be improved. Another advantage of the invention is that the bitumen thus modified has an increased resistance to kerosene and other fuels.

The present invention therefore firstly relates to the use as a modifier for bitumen of a polymer containing free isocyanate functions and resulting from the reaction of:

(A) at least one polyisocyanate;

(B) at least one polydiene polyol; and

(C) at least one ethylene copolymer containing hydroxyl functions.

Preferably, the content of free NCO functions of the modifier polymer is between 1 and 10% by weight, in particular from 1 to 5% by weight, relative to the total weight of the modifier. The subject of the invention is also a composition of bitumen modified with at least one modifier as defined above. The bitumen to be modified can be natural or synthetic; it is generally chosen from bitumens for road surfaces as defined in particular within the meaning of standard NF EN 125 291, bitumens modified by polymers, natural bitumens, semi-blown bitumen, bitumen partially modified with blown bitumen, and all combinations of these bitumens. These bitumens are well known in the state of the art. Their viscosity is not specific, but one could for example consider bitumens having a penetration index between 30 and 220, preferably between 80 and 100.

Bitumens modified by polymers are for example those defined within the meaning of the document ^Λλ Technical Guide: use of modified binders, special bitumens and bitumens with additives in road techniques "published by the Central Laboratory of Bridges and Pavements LCPC CISSN IISI - 1516 15BN 2-7208-7140-4 ". The bitumens modified by polymers are advantageously chosen from those modified by styrene-butadiene or styrene-isoprene copolymers and their mixtures and recycled tires.

The composition according to the invention advantageously comprises 0.5 to 30 parts by weight of the modifier, preferably 3 to 10 parts by weight of the modifier, per 100 parts by weight of bitumen. The basic constituents (A), (B) and (C) of the modifier according to the invention are described in more detail below, as are other possible ingredients (D), (E) and (F).

POLYISOCYANATE (A)

The polyisocyanate (A) is generally chosen from aliphatic, cycloaliphatic and aromatic polyisocyanates well known to those skilled in the art, as well as mixtures of these compounds.

As examples of aliphatic polyisocyanates, mention may be made of hexamethylene diisocyanate (HDI), trimethyl hexamethylene diisocyanate (HMDI), ethylene diisocyanate, ethylidene diisocyanate, propylene diisocyanate, butylene diisocyanate, dichlorohexamethylene diisocyanate, furfurylidene diisocyanate, their derivatives (dimer, trimer, biuret, allophanate) and their mixtures. As examples of cycloaliphatic polyisocyanates, o may be cited isophorone diisocyanate (IPDI), cyclopentylene-1, 3-diisocyanate, cyclohexylene-1, -diisocyanate, cyclohexylene-1, 2-diisocyanate, their derivatives (dimer , trimer, biuret, allophanate) and their mixtures.

As examples of aromatic polyisocyanates, mention may be made of 4,4 "-diphenylmethane diisocyanate (MDI) and its isomers, in particular 2,4'- and 2,2'-diphenylmethane diisocyanate, toluene diisocyanate (TDI) and its isomers, in particular 2,4- and 2,6-toluene diisocyanate, 2, 2-diphenylpropane-4, '-diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, xylene diisocyanate, 1 , 4-naphthalene diisocyanate, 1, 5-naphthylene diisocyanate, azobenzene-4, 4 '-diisocyanate, diphenyl sulfone-4, 4' -diisocyanate, 1-chlorobenzene- 2, 4-diisocyanate, 4, 4 ', 4 "-triisocyanatotripheryl methane, 1, 3, 5-triisocyanato-tetraisocyanate and mixtures thereof.

Preferably, the diisocyanates and more particularly the. MDI and its isomers, TDI and its isomers, HDI, IPDI and their derivatives.

POLYDIENE-POLYOL (B)

The polydiene polyol (B) is generally chosen from the hydroxytelechelic conjugated diene oligomers, the copolymers of conjugated diene and a vinyl or acrylic monomer, the hydroxytelechelic oligomers of butadiene epoxidized on the chain and the hydrogenated hydroxytelechelic oligomers of conjugated dienes.

By way of illustration of polydien-polyols (B) which can be used according to the present invention, mention will be made of hydroxytelechelic conjugated diene oligomers which can be obtained by various processes such as radical polymerization of conjugated diene having 4 to 20 carbon atoms in the presence of a polymerization initiator such as hydrogen peroxide or an azo compound such as azobis-2, 2 '[methyl-2, N- ( hydroxy-2-ethyl) propionamide] or the anionic polymerization of conjugated diene having 4 to 20 carbon atoms in the presence of a catalyst such as naphthalene dilithium.

According to the present invention, the conjugated diene of the polydiene-polyol is chosen in particular from the group comprising butadiene, isoprene, chloroprene, pentadiene-1, 3 and cyclopentadiene. The number-average molar mass of the polyols which can be used can vary from 500 to 15,000 and preferably from 1000 to 3000.

According to the present invention, use will preferably be made of a polydiene polyol based on butadiene. Advantageously, the polydiene polyol comprises 70 to 85 mol%, preferably 75 mol% of units: (—H ₂ C — HC = CH — CH ₂ -) and 15 to 30 mol%, preferably 25 mol% of reasons:

Copolymers of conjugated diene and of a vinyl or acrylic monomer such as styrene or acrylonitrile are also suitable.

We would not depart from the invention if we used hydroxytelechelic oligomers of butadiene epoxidized on the chain, or alternatively hydrogenated hydroxytelechelic oligomers of conjugated dienes.

The OH number of the polydiene polyol (C) expressed in meq / g is advantageously between 0.5 and 5, its viscosity being advantageously between 500 and 100,000 mPa.s at a temperature of 30 ° C.

By way of illustration of polydien-polyols, mention will be made of polybutadienes with hydroxyl endings marketed by the company "ATOFINA" under the names Poly Bd®R45 HT and Poly Bd®R20 LM.

ETHYLENE COPOLYMER (C)

The hydroxyl functions of this copolymer (C) can be provided:

- By grafting or by copolymerization of an unsaturated monomer having at least one hydroxyl function; or

- By grafting or by copolymerization of an unsaturated monomer then reaction of this monomer with a product providing at least one hydroxyl function; or

- By modification of a grafted or copolymerized monomer to create at least one hydroxyl function.

The hydroxyl-functional monomer can be, for example, allyl alcohol, N-hydroxymethyl acrylamide, 2-hydroxyethyl (meth) acrylate (HEA or HEMA) or

(meth) acrylates of diols such as polyethylene glycol (PEG), polyoxypropylene glycol (PPG) or polyoxytetramethylene glycol (PTMG).

The unsaturated monomer can also be a carboxylic acid or an anhydride, for example the acid

(meth) acrylic and maleic anhydride. These acids or anhydrides are then neutralized with a diol such as ethylene glycol, PEG, PPG or PTMG.

The hydroxyl function can also be produced by hydrolysis of a vinyl ester of saturated carboxylic acid such as vinyl acetate or propionate.

This copolymer (C) is advantageously a terpolymer of ethylene, of an unsaturated carboxylic acid ester and of an unsaturated monomer having at least one hydroxyl function, or an ethylene terpolymer, of a vinyl ester d saturated carboxylic acid and an unsaturated monomer having at least one hydroxyl function.

As examples of an unsaturated carboxylic acid ester, mention may be made of alkyl (meth) acrylates, the alkyl group having from 1 to 24 carbon atoms, in particular methyl (ethyl), ethyl, n ~ butyl, isobutyl, 2-ethylhexyl.

As examples of vinyl esters of saturated carboxylic acids, mention may be made of vinyl acetate and vinyl propionate.

As a specific example of this copolymer (C), mention may be made of the ethylene-vinyl acetate-2-hydroxyethyl acrylate terpolymer.

Advantageously, the copolymer (C) is obtained by direct copolymerization (as opposed to grafting).

The copolymer (C) advantageously contains, by weight, 40 to 95% of ethylene, 4 to 40% of comonomer and 1 to 15% of monomer containing at least one hydroxyl function. The melt index of the copolymer (C) according to standard ASTM D 1238-73 is advantageously between 1 and 1000 (g / 10 min).

The copolymer (C) preferably contains from 10 to 45 x 10-- mole of OH per 100 g of copolymer.

OTHER INGREDIENTS

Advantageously, the modifier is prepared in the presence of a monoalcohol ^' (D) chain limiter. By way of example of a monoalcohol, mention may be made of dodecanol.

The compositions according to the present invention may also contain one or more non-hydroxylated resins (E). The preferred resins (E) are aliphatic or aliphatoaromatic (including natural or synthetic terpene resins) and generally do not contain a reactive function with isocyanates. Examples of resins (E) that may be mentioned are alphamethylstyrene resin, a polyethylene homo- or copolymer, a copolymer of ethylene and of an unsaturated carboxylic acid ester, a copolymer of ethylene and a vinyl ester of saturated carboxylic acid such as an ethylene-vinyl acetate (EVA) copolymer, a styrene-butadiene-styrene block copolymer (SBS), a copolymer with styrene-isoprene-styrene blocks (SIS) or these hydrogenated block copolymers (SEBS).

However, it would not depart from the scope of the invention if a polyfunctional hydroxylated resin were used provided that the hydroxyl functions which they provide are taken into account in the calculation of the total NCO / total OH molar ratio and that the viscosity of the compositions of the invention is compatible with their use.

In particular, weakly hydroxylated resins can be used provided that account is taken of the hydroxyl functions which they provide as indicated above and the proportion of alcohol (D) used for the reaction with the excess of polyisocyanate is reduced in proportion.

The compositions according to the present invention may also contain additives (F) such as stabilizers chemically neutral with respect to isocyanates, and waxes.

We will now describe in more detail the reaction products of (A), (B) and (C).

THE REACTION PRODUCT OF (A), (B) and (C)

The modifier according to the invention reaction product of (A), (B) and (C) is known and more fully described by European patent application EP-A-915,942.

The proportions of (B) and (C) can be any, advantageously B / C by weight is between 1/100 and 100/1 and preferably between 1/10 and 2/1.

The possible amount of (D) is such that, by weight, D / (B + C) is between 0 and 5 and preferably between 0 and 2. The NCO / OH molar ratio is chosen in order to avoid gelation during synthesis.

Advantageously, this ratio is between 2 and 30 and preferably between 2 and 5.

The amount of resin (E) is defined by the mass ratio E / (B + C) ranging from 0 to 10, preferably from 0 to 1. The compositions of the invention can be prepared by mixing the various constituents in the molten state.

At the temperature of the mixture, usually between 100 and 150 ° C., the reaction between the NCOs and the OHs is rapid and takes place in a few hours at most. The polymer obtained crosslinks in contact with atmospheric moisture: it is advisable, for its good conservation, to store it sheltered from humidity. Details on the preparation of the modifier polymer of the invention are given in patent application EP-A-915 942.

The reaction between the copolymer (C) and the polyisocyanate (A) is carried out in the presence of a large molar excess of polyisocyanate in order to avoid any undesired increase in viscosity.

The excess required depends on the OH functionality of the copolymer (C), of the polydiene-polyol (B) and on the isocyanate functionality and on the reactivity of the polyisocyanate (A) used (a diisocyanate whose two NCO functions have the same reactivity (for example MDI) requires a greater molar excess than a diisocyanate whose two NCO functions do not have the same reactivity (for example TDI)). The present invention also relates to the use of the modified bitumen composition as defined above for producing road mixes; membranes, coatings or sealants in the field of building and public works (roofs, tanks, landfills, pipes, electrical connections, bridge decks, carpet underlayments, etc.); expansion joints in the building and public works sector (bridges, airports, roadways, etc.); underbody coverings for automobile bodies; pipe coverings; and shock absorbing underlayers in the transportation and building industries. IMPLEMENTATION OF THE MODIFIED BITUMEN COMPOSITION OF THE INVENTION FOR MAKING ROADS

The bitumen composition is used hot (about 150-170 ° C); it is then applied, then compacted. The compacting operation requires a low viscosity of the bituminous mixture, in order to ensure the quality of the road surface. It is therefore necessary that the post-crosslinking of the bituminous formulation does not take place too early. The post-crosslinking of the modifier of the bituminous composition described in the present invention is carried out by humidity, and can therefore only be carried out after the coating has cooled. Compaction operations are generally carried out between 100 and 140 ° C, no post-crosslinking of the formulation is to be feared during this phase and compaction can be carried out under the best conditions. - After cooling (T <100 ° C) , the diffusion of humidity allows the crosslinking of the modifier and the obtaining of a coating whose properties at high temperatures (for example creep, rutting) as well as the resistance to kerosene are improved.

The following Examples illustrate the present invention without, however, limiting its scope. In these examples, the parts and percentages are expressed by weight unless otherwise indicated. The following abbreviations have been used:

PolyBd: polybutadiene with hydroxyl endings

terpo EVA-HEA: ethylene terpolymer - vinyl acetate - 2-hydroxyethyl acrylate

VA: vinyl acetate

HEA: 2-hydroxyethyl acrylate

MDI: 4,4 '- diphenylmethane diisocyanate Mn: number average molecular weight

MFI: flow index.

EXAMPLE 1 SYNTHESIS OF AN ADDITIVE ACCORDING TO THE INVENTION

In a double jacket reactor, dry nitrogen is bubbled for 15 minutes and the double jacket is heated to 130 ° C. The following are loaded into the reactor:

30 parts of PolyBd® R45HT of density 0.90, Mn 2800, viscosity 5000 mPa.s at 30 ° C and OH index 0.83 meq / g, manufactured by the company "ATOFINA";

70 parts of an EVA-HEA terpo containing 32% VA and 2.15% HEA and having an MFI of

450 g / 10 min. (Standard ASTM 1238-73), manufactured by the company "ATOFINA"; and - 100 parts of the alphamethylstyrene resin sold by the. Company "HERCULES", under the name "KRISTALEX® F85.

After a slow melting of the mixture, a vacuum is applied at temperature (130 ° C.) for 1 hour (degassing), then the following is charged:

- 35.4 parts of the MDI marketed by the company ^λλ DO CHEMICAL "under the name - ISONATE® 125"; and - 3.5 parts of dodecanol, these two components having been previously heated to 40 ° C.

The reaction mixture is allowed to react for 4 hours under vacuum at 130 ° C., then the unloading and storage under nitrogen in metal cans of the polymer thus obtained is carried out. EXAMPLES 2 to 4: PREPARATION AND IMPLEMENTATION OF

BITUMEN FORMULATIONS

In order to prepare the samples of these examples, a bitumen with a penetration index of 80-100 produced by the company "NYNAS" was used.

The bitumen is preheated in an oven to 150 ° C in order to facilitate its implementation. It is then introduced into a melter regulated at 150 ° C. It is poured into a 2 mm thick plate and then cooled to room temperature. Test pieces necessary for characterization are cut from said plate (Reference example 2).

To prepare specimens of modified bitumen according to the present invention, a quantity of this same bitumen is also preheated to 150 ° C., then introduced into two melters regulated at 150 ° C. The additive prepared in Example 1, preheated in an oven at 130 ° C, is introduced in an amount representing 3% and 10% by mass of the bitumen in each of the melters (Examples respectively 3 and 4). The contents of each of the melters are then mixed at 150 ° C. using a paddle stirrer (100 rpm) for 5 minutes, then each mixture is poured into a plate 2 mm thick and cools to room temperature. Then, cut test pieces necessary for characterization. All the test pieces (Examples 2 to 4) are placed for 7 days in a climatic chamber at 40 ° C. and 90% residual humidity, in order to allow post-crosslinking by humidity. The test pieces are then stored in a dry atmosphere until evaluation.

EXAMPLE 5: CHARACTERIZATION OF MODIFIED BITUMEN

The properties of bituminous binders are evaluated according to the specifications proposed by the SHRP program (High Ay Research Program) recognized by the profession. This evaluation made thanks to Bending Beam Rheometer (BBR) tests and mechanical analyzes dynamics (DMA G), makes it possible to determine the plasticity interval (or plasticity interval PI) of the bituminous binder, that is to say its range of temperatures of use, by the data of a high limit temperature T _maχ and an . ^' low limit temperature T _m - _j _ _n .

Test (BBR)

The determination of the FRAASS point is still subject to discussion as a parameter for characterizing the behavior at low temperatures of bitumens and modified bitumens. The SHRP program suggests instead the use of BBR (see SHRP 1002, SHRP product catalog, 1992). This test, which consists in imposing on a rod-shaped test piece a constant charge at a series of determined temperatures and measuring the deformation of the test piece as a function of the charging time can be carried out on pure bitumens, special bitumens or bitumens modified by polymers. The specification by SHRP indicates that the hardness of the bituminous binder measured by BBR must remain below 300 MPa. In the present example, this limit value was therefore used to determine the lower limit of the temperature of use of the binder.

DMA G *

The SHRP program specifies that the value G / sin δ must be greater than 1 kPa at the frequency of 10 radians / sec. In the present example, this limit value was therefore used to determine the upper limit of the temperature of use of the binder, temperature directly linked to the creep properties.

Kerosene aging

In order to determine the resistance to kerosene, a test of immersion in kerosene at room temperature was carried out. To this end, test tubes of the formulations Examples 2, 3 and 4 were immersed in JET Al kerosene (Elf Special Fuels Solaize) for 10 minutes, then dried for 10 minutes. The determination of the loss of mass during this aging makes it possible to illustrate the resistance to kerosene of the various formulations tested.

The results of these tests are collated in the Table below.

Board

Claims

1 - Use as a modifier for bitumen of a polymer containing free isocyanate functions and resulting from the reaction of: (A) at least one polyisocyanate;

(B) at least one polydiene polyol; and

(C) at least one ethylene copolymer containing hydroxyl functions.

2 - Composition of bitumen modified with at least one polymer containing free isocyanate functions and resulting from the reaction of:

(A) at least one polyisocyanate;

(B) at least one polydiene polyol; and

(C) at least one ethylene copolymer containing hydroxyl functions.

3 - Composition according to claim 2, characterized in that the bitumen is chosen from bitumens for road surfaces, bitumens modified by polymers, natural bitumens, semi-blown bitumen, bitumen partially modified with blown bitumen, and all ^' combinations of these bitumens.

4 - Composition according to one of Claims 2 and 3, characterized in that the bitumen has a penetration index between 30 and 220. 5 - Composition according to Claim 4, characterized in that the bitumen has an index of penetration between 80 and 100.

6 - Composition according to one of claims 2 to 4, characterized in that it comprises 0.5 to 30 parts by weight of the modifier per 100 parts by weight of bitumen.

7 - Composition according to claim 6, characterized in that it comprises 3 to 10 parts by weight of the modifier per 100 parts by weight of bitumen. 8 - Composition according to one of claims 2 to 7, characterized in that the polyisocyanate (A) is chosen from aliphatic polyisocyanates, cycloaliphatic and aromatic as well as mixtures of these polyisocyanates.

9 - Composition according to claim 8, characterized in that the polyisocyanate (A) is 4, 4 '-diphenylmethane diisocyanate.

10 - Composition according to one of claims 2 to 9, characterized in that the polydiene-polyol (B) is chosen from oligomers of hydroxytelechelic conjugated diene, copolymers of conjugated diene and vinyl monomer. or acrylic, hydroxytelechelic oligomers of epoxidized butadiene on the chain and hydrogenated hydroxytelechelic oligomers of conjugated dienes.

11 - Composition according to claim 10, characterized in that the polydiene-polyol (B) is a polybutadiene with hydroxyl endings.

12 - Composition according to one of claims 2 to 11, characterized in that the polydiene-polyol (B) has an OH number expressed in meq / g between 0.5 and .5. 13 - Composition according to one of claims

2 to 12, characterized in that the polydiene-polyol (B) has a viscosity of between 500 and 100,000 Pa.s at 30 ° C.

14 - Composition according to one of claims ^' 2 to 13, characterized in that the copolymer (C) is a terpolymer of ethylene, of an unsaturated carboxylic acid ester and of an unsaturated monomer having at least a hydroxyl function, or a terpolymer of ethylene, of a vinyl ester of saturated carboxylic acid and of an unsaturated monomer having at least one hydroxyl function.

15 - Composition according to claim 14, characterized in that the polymer (C) - is an ethylene-vinyl acetate terpolymer - 2-hydroxyethyl acrylate. 16 - Composition according to one of claims 2 to 15, characterized in that the modifier was prepared in the presence of at least one monoalcohol (D) chain limiter. 17 - Composition according to claim 16, characterized in that the monoalcohol is dodecanol.

18 - Composition according to one of claims 2 to 17, characterized in that the modifier was prepared in the presence ^'of at least one non-hydroxylated resin (E).

19 - Composition according to claim- 18, characterized in that the non-hydroxylated resin or resins (E) are chosen from an alphamethylstyrene resin, a polyethylene homo- or copolymer, a copolymer of ethylene and of an ester unsaturated carboxylic acid, a copolymer of ethylene and a vinyl ester of saturated carboxylic acid such as an ethylene-vinyl acetate (EVA) copolymer, a styrene-butadiene-styrene block copolymer (SBS), a styrene-isoprene-styrene block copolymer (SIS) or these hydrogenated block copolymers (SEBS).

20 - Composition according to one of claims 2 to 19, characterized in that the modifier has been prepared in the presence of at least one additive (F) chosen from stabilizers chemically neutral vis-à-vis isocyanates, and raincoats.

21 - Use of the modified bitumen composition as defined in one of claims 2 to 20, for producing road mixes; membranes, coatings or sealants and expansion joints in the field of building and public works; underbody coverings for automobile bodies; pipe coverings; and shock absorbing underlayers in the transportation and building industries.