EP2203419A1

EP2203419A1 - Novel surfactants with a polyethersulfonate structure method for production thereof and use thereof for tertiary crude oil production

Info

Publication number: EP2203419A1
Application number: EP08839255A
Authority: EP
Inventors: Christian Bittner; Günter OETTER; Ulrich Steinbrenner; Jürgen HUFF; Marcus Guzmann
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2007-10-16
Filing date: 2008-10-15
Publication date: 2010-07-07
Also published as: US20100213409A1; JP2011502184A; WO2009050179A1; US8465668B2

Abstract

Surfactants with a polyethersulfonate structure having a propanoylsulphonic acid as head group, method for production of such surfactants and use thereof for tertiary crude oil production.

Description

Novel surfactants with polyethersulfonate structure, process for their preparation and their use for tertiary mineral oil production

description

The present invention relates to novel surfactants having a polyethersulfonate structure, which have a Propanonylsulfonsäuregruppe as a head group, a process for the preparation of such surfactants and their use for tertiary mineral oil production.

In natural oil deposits, petroleum is present in the cavities of porous reservoirs, which are closed to the earth's surface of impermeable cover layers. The cavities may be very fine cavities, capillaries, pores or the like. Fine pore necks, for example, have a diameter of only about 1 micron. In addition to crude oil, including natural gas, a deposit contains more or less saline water. The salinity of reservoir water is often 5 to 20 wt.%; but there are also deposits with a salinity of up to 27 wt.%. The dissolved salts may, for example, be alkali metal salts, but in some deposits the reservoir water also contains relatively high levels of alkaline earth metal ions, for example up to 5% by weight of calcium ions and / or magnesium ions.

In the case of oil production, a distinction is made between primary, secondary and tertiary production.

In primary production, after drilling the deposit, petroleum automatically streams through the borehole due to the inherent pressure of the deposit. The autogenous pressure can be caused, for example, by gases present in the reservoir, such as methane, ethane or propane. Depending on the type of deposit, however, only approx. 5 to 10% of the quantity of crude oil in the deposit can be pumped by means of the primary extraction, after which the autogenous pressure is no longer sufficient for production.

After the primary funding, therefore, the secondary funding is used. In secondary production, additional wells will be drilled into the oil-bearing formation in addition to the wells that serve to extract the oil, known as production wells. Through these so-called injection wells water is injected into the reservoir to maintain or increase the pressure. By injecting the water, the oil is slowly pressed by the cavities in the formation starting from the injection hole in the direction of the production bore. However, this only works as long as the cavities are completely filled with oil and the more viscous oil is pushed through the water (see Figure 1). As soon as the low-viscosity water breaks through cavities, it flows from this point on the path of the least resistance, ie through the channel formed and no longer pushes the oil in front of him. This situation is shown in Figure 2: Due to the different polarity of oil and water results there is a high interfacial energy or interfacial tension between the two components. Therefore, both of them occupy the smallest contact area with each other, resulting in a spherical oil drop which no longer fits through the fine capillaries. At the end of the flood, the oil is trapped in discontinuous form (scattered globules) in the capillaries.

By means of primary and secondary production, as a rule only about 30 to 35% of the amount of crude oil in the deposit can be extracted.

It is known to further increase the oil yield by measures of tertiary oil production. An overview of tertiary oil production can be found, for example, in the Journal of Petroleum Science and Engineering 19 (1998) 265-280. Tertiary oil extraction includes, for example, heat processes in which hot water or superheated steam is injected into the deposit. As a result, the viscosity of the oil is reduced. As a flood medium, gases such as CO2 or nitrogen can be used.

Tertiary oil production also includes processes using suitable chemicals as auxiliaries for oil extraction. With these, the situation can be influenced towards the end of the flood and thereby also promote oil that has been held in the rock formation until then.

Viscous and capillary forces act on the oil trapped in the pores of the reservoir rock towards the end of the secondary production, and the ratio of these two forces to one another determines the microscopic oil removal. By means of a dimensionless parameter, the so-called capillary number, the influence of these forces is described. It is the ratio of the viscosity forces (velocity x viscosity of the pressing phase) to the capillary forces (interfacial tension between oil and water x wetting of the rock):

N = ^{. μV} σ cosθ

Where μ is the viscosity of the oil mobilizing fluid, v is the Darcy velocity (flow per unit area), σ is the interfacial tension between petroleum mobilizing liquid and petroleum, and θ is the contact angle between petroleum and rock (C. Melrose, CF Brandner, J. Canadian Petr. Techn. 58, Oct.-Dec., 1974). The higher the capillary number, the greater the mobilization of the oil and thus also the degree of de-oiling.

It is known in the art, that the capillary number "is ^6, and that it is necessary for the capillarity to about ^10" near the end of secondary oil recovery in the range of about 10 to increase ^{from 3} to 10 ^"2 to mobilize additional mineral oil. For this purpose, can For example, lower the interfacial tension σ between oil and aqueous phase by the addition of suitable surfactants. This technique is also called as "surfactant" is known. To the tenside are in particular surfactants which σ values of <10 ^"2 mN / m (ultralow interfacial tension) may decrease. In this way, the oil droplets can be changed in shape and forced through the flood water through the capillary openings.

It is desirable that the oil droplets subsequently combine to form a continuous oil bank. This is shown schematically in Figure 3. The formation of a continuous oil bank has two advantages: On the one hand, as the continuous oil bank progresses through new porous rock, the oil drops located there can merge with the bank. Furthermore, the oil-water interface is significantly reduced by the union of oil drops to an oil bank and thus releases no longer needed surfactant. The released surfactant may then mobilize residual oil in the formation. This is shown schematically in Figure 4. Also, to combine the oil drops to an oil bank and to accommodate new oil drops in the oil bank an ultra-low interfacial tension between the water and the oil phase is required. Otherwise, individual drops of oil remain or are not absorbed into the oil bank. This reduces the efficiency of surfactant flooding.

In general, water is not injected into the formation after the surfactant flooding to maintain the pressure, but a higher-viscosity, aqueous solution of a highly thickening polymer. This technique is known as "polymer flooding".

During surfactant flooding, the surfactants should form a microemulsion (Winsor type III) with the water and oil phases. A microemulsion (Winsor type III) is not an emulsion with particularly small droplets, but a thermodynamically stable, liquid mixture of water, oil and surfactants, which has a very low interfacial tension and usually has a low viscosity. It is in balance with excess water and excess oil. A low viscosity is desirable for transporting the emulsion in the petroleum formation. If the viscosity of the phase to be transported is too high, a very high pressure would have to be exerted in the course of polymer flooding. This is on the one hand expensive, but above all there is also the danger that unwanted new voids are blasted into the oil formation by the pressure. Furthermore, a combination of the mobilized oil droplets is inhibited to a continuous oil bank in case of too high viscosities.

The requirements for surfactants for tertiary mineral oil production differ significantly from the requirements for surfactants for other applications.

The surfactants should reduce the interfacial tension between water and oil (usually approx. 20 mN / m) to particularly low values of less than 10 " ² mN / m sufficient mobilization of petroleum. This must be done at the usual storage temperatures of about 30 to about 130 ⁰ C and in the presence of highly saline water, especially in the presence of high levels of calcium and / or magnesium ions; The surfactants must therefore be soluble in highly saline reservoir water. The temperature window, within which a

Microemulsion forms, it should be as wide as possible. To avoid surfactant losses in the formation, the surfactants should have a low tendency to form viscous or large surfactant superstructures and have a low adsorption behavior. Furthermore, the surfactants should have a high chemical stability under the conditions prevailing in the formation conditions. Above all, this includes a high long-term stability: the migration speed of the surfactant flood in the formation is often less than 1 m / day. Depending on the distance between the injection and production well, therefore, the residence times of the surfactant in the crude oil reservoir can be several months.

Various polyethersulfonates have been proposed for use in tertiary petroleum production.

No. 3,811,505 discloses a mixture of an anionic and a nonionic surfactant for use in deposits whose deposit water contains 0.5 to 0.9% by weight of polyvalent ions. The anionic surfactants are alkyl sulfonates or alkyl phosphates having in each case 5 to 25 C atoms, alkylarylsulfonates or alkylarylsulfonates whose alkyl radical has in each case 5 to 25 C atoms. The nonionic surfactants are polyethoxylated alkylphenols which have 6 to 20 ethoxy groups and whose alkyl radical has 5 to 20 C atoms or polyethoxylated aliphatic alcohols having 6 to 20 C atoms and 6 to 20 ethoxy groups.

US 3,811,1504 discloses a mixture of 2 different anionic surfactants and a nonionic surfactant for use in reservoirs whose reservoir water contains 0.15 to 1.2% calcium and magnesium ions. The first anionic surfactant is alkyl or alkylaryl sulfonates, the second is alkyl polyethoxy sulfates and the nonionic surfactant is polyethoxylated aliphatic or aromatic alcohols. Similarly, composite surfactant blends are disclosed, for example, in US 3,508,621, US 3,811,507 or 3,890,239.

US 4,077,471 discloses a surfactant mixture for use in a formation, the

Deposit water has a salt content of 7 to 22%. The mixture comprises a water-soluble alkylpolyalkoxyalkylsulfonate or alkylarylpolyalkoxyalkylsulfonate and a water-insoluble nonionic surfactant of an ethoxylated aliphatic alcohol or an ethoxylated, alkyl-substituted aromatic alcohol.

EP 003 183 B1 discloses surfactants of the general formula RO-polypropoxy-polyethoxy-X, where X is a sulfate, sulfonate, phosphate or carboxylic acid group. At R it can be in a preferred embodiment of the invention is a branched alkyl radical having 10 to 16 carbon atoms, for example an isotridecyl radical.

For the preparation of polyethersulfonates, it is possible to start with corresponding alkylalkoxylates whose terminal OH groups are used in further reaction steps in order to provide the alkylalkoxylates with a terminal sulphonic acid group. For this purpose, in a known manner, the terminal OH group of the alkyl alkoxylate can be substituted by a suitable leaving group, for example by reacting SOCb, PCb or COCb, whereby OH- is substituted by Cl-. In a second step, the Cl atom can be replaced nucleophically by -SO3H by reaction with Na2SO3. This reaction is particularly problematic for alkyl alkoxylates with larger carbon residues and relatively short alkoxy chains, because the alkyl alkoxylates are then no longer particularly soluble in water. The result is often incomplete reactions, resulting in a mixture of nonionic surfactants and anionically modified surfactants.

Alternatively, one can react the OH group of the alkyl alkoxylate with propane sultone, a cyclic anhydride of 3-hydroxypropanesulfonic acid. Propansulton has the disadvantage that it is toxic and carcinogenic. In addition, reactions with bulky alcohols (such as secondary alcohols) are often incomplete.

Furthermore, as disclosed in US Pat. No. 4,978,780, vinyl sulfonic acid or a salt thereof can be added to the OH group of the alkoxylate. However, vinylsulfonic acid is a relatively expensive chemical.

The object of the invention was to provide an improved process for the preparation of surfactants having a polyethersulfonate structure.

Accordingly, surfactants of the general formula (I)

found, where

R ^{1 is} a straight-chain, branched, saturated or unsaturated aliphatic and / or aromatic hydrocarbon radical having 6 to 30 carbon atoms,

R ² independently of one another for each of the k alkoxy units is hydrogen or a straight-chain, branched, aliphatic or aromatic hydrocarbon radical having 1 to 10 carbon atoms,

• k for a number from 0 to 35, and • M stands for H ⁺ and / or an x-valent counterion V _x Y ^{x +} .

Furthermore, a process for the preparation of such surfactants has been found and their use for various purposes, including tertiary mineral oil production.

Attached pictures:

Fig. 1 Situation at the beginning of secondary oil production: Completely oil-filled rock spore.

Fig. 2 Situation towards the end of the secondary oil production: The flood water has formed a channel and flows through the canal without taking any further oil.

Fig. 3 Schematic representation of surfactant flooding in a petroleum formation: from the

Rock spores released oil droplets before (A) and after (B) the union to a continuous oil bank.

Fig. 4 Schematic representation of the progress of the continuous oil bank in the petroleum formation. The oil bank absorbs new oil droplets in the direction of flow.

Contrary to the current direction, surfactant is released.

More specifically, the following is to be accomplished for the invention:

The surfactants of the invention have the general formula

The surfactants (I) according to the invention consist of a hydrocarbon radical R ¹ , a polyoxyalkylene group of k alkoxy units, where the k alkoxy units may be identical or different and have a propanone sulfonic acid group as head group.

In the formula (I), R ^{1 represents} a straight-chain, branched, saturated or unsaturated aliphatic and / or aromatic hydrocarbon radical having 6 to 30 carbon atoms, preferably 10 to 22 carbon atoms. Examples of suitable radicals R ¹ include, in particular, linear or branched C 10 - to C 22 -alkyl radicals and also linear or branched C 12- to C 22 -alkenyl radicals. They are preferably linear or branched C 10 - to C 22 -alkyl radicals, more preferably linear or branched C 12 - to C 20 -alkyl radicals, and very particularly preferably linear or branched C 16- to cis-alkyl radicals. If the residues are branched, degrees of branching of more than 0.5 are preferred.

The radicals R ² are each independently H or straight-chain, branched, aliphatic or aromatic hydrocarbon radicals having 1 to 10 carbon atoms. R ² is preferably H, methyl, ethyl and / or phenyl, and particularly preferably H or methyl. In other words, the alkoxy groups are preferably ethoxy groups and / or propoxy groups. In the above formula, the representation of the alkoxy group as -CH ² CH (R ² ) O- should also expressly include units of the formula -CH (R ² ) CH ² O-, ie incorporation of the alkoxy group into the surfactant in inverse orientation, it being understood that in a surfactant molecule also both orders can be represented. Preferred is an orientation as shown in formula (I). Preferably, at least 50% of the alkoxy groups present in the surfactant are ethoxy groups.

The number k in the above formula (I) here stands for a number from 0 to 35, preferably 1 to 35, particularly preferably 1 to 20 and very particularly preferably 2 to 15. In this case, it relates in a known manner to the mean value of Of course, the average value does not have to be a natural number but can also be any rational number.

In formula (I), M is H ⁺ or an x-valent counterion V _X Y ^{X +} . x stands for the charge of the counterion. It is preferably a monovalent counterion, such as NH ₄ ⁺ -, ammonium ions with organic radicals or alkali metal ions. Preferably, Y is Li ⁺ , Na ⁺ and K ⁺ , and particularly preferred is Na ⁺ . Thus, the alkyl ether sulfonate may be present as a free acid or as a salt thereof.

In a preferred embodiment of the invention, the surfactants of the invention are those of the general formula (II)

R ¹ O- (CH ₂ CH (R ² ) O) n (CH ₂ CH ² O) _m -CH ₂ C (O) -CH ₂ -SO 3 M (II).

The number n here stands for values from 0 to 15, preferably 0 to 7 and particularly preferably 0 to 5, and m stands for values from 0 to 20, preferably 1 to 20, particularly preferably 2 to 15, where the sum of n and m each gives the value k defined above. Preferably, m> n, ie in the preferred variant, the number of ethoxy groups is greater than that of the alkoxy groups. The arrangement of alkoxy groups and ethoxy groups in the surfactant of the present invention - if both types of groups are present - may be random or alternating, or there may be a block structure. It is preferably a block structure in which the alkoxy and ethoxy groups are actually arranged in the order of R ¹ O - alkoxy block - ethoxy block - CH ₂ C (O) -CH ₂ -SO ₃ M.

The preparation of the surfactants according to the invention can be carried out in a three-stage synthesis, wherein an alkyl alkoxylate of the general formula (III) is prepared in a first synthesis stage.

The alkyl alkoxylates (III) can be prepared in a manner known in principle by alkoxylation of an alcohol R ¹ -OH with alkylene oxides

O

_> 2 /

R-, terminating the alkoxylation using propylene oxide to give an alkyl alkoxylate having the terminal group - CH ₂ CH (CHs) -OH shown in formula (III).

The alcohols R ¹ -OH are hereby selected according to the desired hydrophobic radical R ¹ in the surfactant. Examples of suitable alcohols include pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol or eicosanol. These may each be 1-alkanols or else alkanols in which the OH group is not arranged in the 1-position. The alcohols can be straight-chain or branched. These may be, for example, fatty alcohols or, preferably, alcohols which can be obtained by hydroformylation of olefins. The latter are also known as oxo-alcohols. Of course, not only pure alcohols can be used for the synthesis, but also typical technical mixtures of various alcohols.

According to the invention, the alkoxylation is carried out by first reacting the alcohol with any alkylene oxides, depending on the desired properties of the surfactant. After the consumption of all or at least most of the alkylene oxides used, at the end of the alkoxylation, at least 1 mol of propylene oxide per mole of alcohol is again added in order to obtain a product which is terminated with -CH ₂ CH (CH 3) -OH units. The alkoxylation thus takes place in total with k + 1 mol of alkylene oxide per mol of alcohol. Since the alkoxylation proceeds statistically, it is advisable to use the propylene oxide at least in slight excess in order to obtain a product completely terminated with - CH 2 CH (CH 3) -OH units.

The alkoxylation can be carried out in principle by methods known to the skilled worker using known alkoxylation catalysts, with the proviso that the alkoxylation is carried out so that the terminal propylene oxide group actually predominantly in the orientation -CH 2 CH (CH 3) -OH and not in the opposite orientation as CH (CH3) -CH2θH is incorporated. It is known to those skilled in the art that the orientation of alkylene oxide groups by the choice of

Can affect alkoxylation catalyst. For example, basic catalysis or catalysis by DMC catalysts predominantly results in incorporation of the alkoxy groups in -CH 2 CH (CH 3) -OH orientation, whereas acidic catalysis results in significant levels of -CH (CH 3) -CH 2 O- orientation units.

In the base-catalyzed alkoxylation, the alcohol R ¹ -OH can be mixed in a pressure reactor with alkali metal hydroxides, preferably potassium hydroxide or with alkali metal alkoxides such as sodium methylate. By reduced pressure (eg <100 mbar) and / or increasing the temperature (30 to 150 ⁰ C) can still be withdrawn in the mixture existing water. The alcohol is then present in the form of the corresponding alcoholate. Subsequently, it is inertized with inert gas (eg nitrogen) and the alkylene oxide (s) are at temperatures of 60 to 180 ⁰ C up to a pressure of max. 10 bar, provided that the addition of the alkylene oxides is terminated with the addition of at least one mole of propylene oxide per mole of alcohol such that the synthesized alkyl alkoxylate has a -CH 2 CH (CH 3) -OH group as the terminal group. Thereafter, the catalyst can be neutralized by addition of acid (eg acetic acid or phosphoric acid) and can be filtered off if necessary. Alkyl alkoxylates prepared by KOH catalysis generally have a relatively broad molecular weight distribution.

In a preferred embodiment of the invention, the alkyl alkoxylates (III) are synthesized by techniques known to those skilled in the art, which lead to narrower molecular weight distributions than in base-catalyzed synthesis. For this purpose, for example, double hydroxide clays as described in DE 43 25 237 A1 can be used as the catalyst. The alkoxylation can be carried out particularly preferably using double metal cyanide catalysts (DMC catalysts). Suitable DMC catalysts are disclosed, for example, in DE 102 43 361 A1, in particular sections [0029] to [0041], and the literature cited therein. For example, Zn-Co type catalysts can be used. To carry out the reaction, the alcohol R ¹ -OH may be added with the catalyst, the mixture dehydrated as described above and reacted with the alkylene oxides as described. The catalyst can remain in the product due to its small amounts. By DMC catalysis prepared surfactants according to the invention are characterized in that they result in a better lowering of the interfacial tension in the water-petroleum system than products produced by means of KOH catalysis.

It is of course also possible to carry out the synthesis in two stages by first catalyzing the alkoxylation acidic and converts at the latest before the addition of the last mole of propylene oxide to basic catalysis.

In a further synthesis step, the alkyl alkoxylate (III) is oxidized to the alkyl alkoxylate (IV), which has an acetonyl group as the terminal group.

oxidation

(Hi) (IV)

The oxidation may be carried out by methods known to those skilled in the art, for example by oxidation with H2O2 and a transition metal catalyst or by oxidation with O2 using a suitable catalyst such as Pd / C. As a rule, sales at this level exceed 90%.

The resulting acetonyl-terminated alkyl alkoxylate (IV) can finally be reacted with SO 3 or another SO 3 source, such as, for example, oleum or CI-SO 3 H to give the surfactant (I) according to the invention.

(IV) (i)

The reaction can be carried out, for example, according to the methods described by US 4,987,249, US 5,430,180 or W. Grot, J. Org. Chem. 30 (1965), 515-517. As a rule, sales at this level are more than 90%. After carrying out the sulfonation, the reaction mixture can be neutralized with a base such as NaOH or KOH. The surfactants (I) according to the invention can in principle be used in all applications in which alkylpolyethersulfonates are usually used as surfactants. By appropriate choice of R ¹ and length and type of alkoxy group, the properties of the surfactants (I) according to the invention can be adapted in a simple manner to the respective application. They can be used, for example, in washing and cleaning agents, in ore production, in metalworking, in textile production, in leather processing, in emulsion stabilization or in the formulation of pesticides.

In a preferred embodiment of the invention, the surfactants according to the invention are used for tertiary mineral oil extraction (EOR). They cause a particularly good mobilization of crude oil in the petroleum formation by a strong reduction of the interfacial tension between oil and water.

For this purpose they are pressed in the form of a suitable formulation through at least one injection hole in the oil reservoir, and the deposit is removed through at least one production well crude oil or a crude oil-water emulsion. As a rule, a deposit is provided with multiple injection wells and multiple production wells. Following the pressing in of the surfactant formulation, the so-called "surfactant flooding", water can be injected into the formation to maintain the pressure ("water flooding") or, preferably, a more viscous aqueous solution of a polymer having a pronounced thickening effect ("polymer flooding") However, techniques are also known according to which the surfactants are first of all allowed to act on the formation.The person skilled in the art knows details of the technical implementation of "surfactant flooding", "flooding" and "polymer flooding", and he uses an appropriate one depending on the nature of the deposit Technology.

The surfactants according to the invention can be used for surfactant flooding, preferably in aqueous formulation. In addition to water, the formulations may optionally contain as solvent not more than 50% by weight, preferably not more than 20% by weight, of water-miscible alcohols.

For tertiary mineral oil extraction, in each case only one of the surfactants (I) according to the invention can be used. However, preference is given to using a formulation which comprises at least one surfactant (I) according to the invention and at least one further surfactant.

The surfactants according to the invention can be used here as surfactants or else as cosurfactants. "Cosurfactant", also referred to as "secondary surfactant", is understood in a manner known in principle to be a surfactant which is admixed in lesser amounts with other surfactants or surfactant mixtures in order to improve their property profile. The amount of all surfactants (I) according to the invention together with respect to the total amount of all surfactants used in a surfactant mixture will be apparent to those skilled in the art determined according to the nature of the desired properties. The amount of surfactants (I) according to the invention is, as a rule, from 1 to 99% by weight, based on the total amount of all surfactants in the mixture. The amount is preferably 10 to 95% by weight.

Examples of other surfactants which can be used in addition to the surfactants (I) include anionic surfactants, in particular organic sulfonates, such as olefin sulfonates or alkylarylsulfonates, nonionic surfactants or anionic surfactants which are prepared by anionic modification of nonionic surfactants, such as ether sulfates, ether sulfonates or ether carboxylates or alkyl polyols and / or alkyl polyglucosides. Furthermore, cationic and / or betainic surfactants can be used.

In addition to the surfactants, the formulations may also contain other components such as, for example, C 1 to C 8 alcohols and / or basic salts (so-called "alkaline surfactant flooding") .For example, such retention may reduce retention in the formation.

Mixtures preferred for tertiary mineral oil extraction, which comprise surfactants (I) according to the invention, are described below.

In a preferred embodiment of the invention can for tertiary oil production a

Mixture (M) of at least one surfactant (I) according to the invention (hereinafter also referred to as

M1) and at least one anionic surfactant (M2).

Such mixtures are particularly suitable for use in high saline deposits. For use, the mixtures may be formulated as described above, preferably with suitable solvents or mixtures of solvents.

As component (M2) in addition to the surfactants (M1) according to the invention, especially nonionic surfactants of the general formula (V)

R ³ - (CH ₂ CH (R ² ) O) n (CH ₂ CH ₂ O) _m -H (V)

suitable, wherein the indices n and m and R ^{2 have} the above meaning, and wherein R ³ is an aliphatic or araliphatic C10 to C 20 hydrocarbon residue, preferably an aliphatic and / or aromatic C ₄ - to cis hydrocarbon residue , The hydrocarbon radicals may be, for example, 4-dodecylphenyl radicals or hexadecyl, heptadecyl or octadecyl radicals.

Preference is furthermore given to mixtures of at least one ionically behaving surfactant (MT) and at least one nonionic surfactant (M2 '), at least one of the surfactants (M 1') or (M2) being an inventive surfactant (I ). By ionic surfactants and nonionic "surfactants" are in each case surfactants in which the head group comprises both ionic and nonionic structural units and in which, depending on the chemical structure and / or operating conditions, nonionic behavior or ionic behavior dominates A typical nonionic surfactant with polyether units behaves in an oil At lower temperatures, such surfactants initially form an oil-in-water emulsion, ie an emulsion of oil in a continuous water phase. Oil emulsion, which is an emulsion of water in a continuous oil phase, which can be monitored, for example, by a conductivity measurement

Water phase in a discontinuous water phase is associated with a significant drop in conductivity. Ionically-behaving surfactants behave inversely and become more hydrophilic with increasing temperature. A water-in-oil emulsion thus changes with increasing temperature into an oil-in-water emulsion, which is also easy to follow by a conductivity measurement.

In a further preferred embodiment, the mixture (M) in addition to the components (M1) and (M2) still comprises a polymeric cosurfactant (M3). The amount of cosurfactant (M3) is not more than 49.9% by weight with respect to the total amount of all surfactants used (M1), (M2) and (M3). Preferably, the amount is 1 to 10 wt.%. Such polymeric cosurfactants can advantageously reduce the amount of surfactant required to form a microemulsion. Such polymeric cosurfactants are therefore also referred to as "microemulsion boosters".

The polymeric cosurfactants (M3) are amphiphilic block copolymers comprising at least one hydrophilic and at least one hydrophobic block. They preferably have molecular masses M _n of 1000 to 50 000 g / mol. As a rule, the hydrophilic and hydrophobic blocks should have at least one molar mass of in each case 500 g / mol, preferably 750 g / mol and particularly preferably 1000 g / mol. The hydrophobic and hydrophilic blocks can be linked together in various ways. They may be, for example, two-block copolymers or multi-block copolymers in which the hydrophobic and hydrophilic blocks are arranged alternately. The polymeric cosurfactants (M3) may be linear, branched or star-shaped or may also be a comb polymer having a backbone and one or more side chains attached thereto.

Preference is given to block copolymers which have polyethylene oxide blocks or random polyethylene oxide / polypropylene oxide blocks as hydrophilic blocks, where the proportion of propylene oxide should not exceed 40 mol%, preferably 20 mol% and particularly preferably 10 mol% relative to the sum of the ethylene oxide and propylene oxide units incorporated in the block. They are preferably pure polyethylene oxide blocks. The hydrophobic blocks may be, for example, blocks of polypropylene oxide or C ₄ bis Ci2-alkylene oxides act. Furthermore, hydrophobic blocks can be constructed, for example, from hydrocarbon units or (meth) acrylic acid esters.

Preferred polymeric cosurfactants (M3) include polypropylene oxide-polyethylene oxide block copolymers, polyisobutene-polyethylene oxide block copolymers and comb polymers having polyethylene oxide side chains and a hydrophobic main chain, the main chain preferably comprising substantially olefins or (meth) acrylates as building blocks. As used herein, the term "polyethylene oxide" is intended to include polyethylene oxide blocks comprising propylene oxide units as defined above Further details of the preferred polymeric cosurfactants (M3) are disclosed in WO 2006/131541.

Claims

claims

1. Surfactants of the general formula (I)

in which

• k is a number from 0 to 35 and • M is H ⁺ and / or an x-valent counterion V _x Y ^{x +} .

2. Surfactants according to claim 1, characterized in that k is a number from 1 to 20.

3. Surfactants according to claim 1 or 2, characterized in that at least 50% of the radicals R ² in the surfactant is hydrogen.

4. Surfactants according to one of claims 1 to 3, characterized in that R ² is hydrogen or methyl.

5. Surfactants according to one of claims 1 to 4, characterized in that R ¹ is linear or branched C 10 to C 22 alkyl radicals.

6. Surfactants according to one of claims 1 to 4, characterized in that R ¹ is linear or branched C10 to C 20 -alkyl radicals.

7. Process for the preparation of surfactants according to one of claims 1 to 6 comprising the following process steps:

Alkoxylating an alcohol of the general formula R ¹ -OH with k + 1 mol

O

R _> -2 / \

Alkylene oxides per mole of alcohol to the alkyl alkoxylate (III)

the alkoxylation being carried out by using at least 1 mol of propylene oxide per mole of alcohol to complete the alkoxylation,

Oxidizing the alkyl alkoxylate (III) by means of a suitable oxidizing agent to give a ω-acetonylalkyl alkoxylate (IV)

such as

Reacting the ω-acetonylalkylalkoxylate (IV) with a sulphonating agent to give the surfactant (I)

8. The method according to claim 7, characterized in that one uses as sulfonating agent one selected from the group of SO3, oleum or chlorosulfonic acid.

9. The method according to claim 7 or 8, characterized in that the surfactant (I) is neutralized after sulfonation with a suitable base.

10. A surfactant mixture (M) comprising at least two different surfactants (M1) and (M2), characterized in that at least one of the surfactants is an inventive surfactant (I) according to one of claims 1 to 6.

1 1. A surfactant mixture (M) according to claim 10, characterized in that (M1) is a surfactant (I) according to the invention and (M2) is at least one nonionic surfactant.

12. surfactant mixture (M) according to claim 10, characterized in that it is at least one ionic behaving surfactant (M-T), and at least one non-ionic behaving surfactant (M2 ').

13. surfactant mixture (M) according to any one of claims 10 to 12, characterized in that the mixture additionally up to 49.9 wt.% With respect to the sum of all surfactants in the mixture of at least one polymeric cosurfactant (M3).

14. A surfactant mixture (M) according to claim 13, characterized in that it is the polymeric cosurfactant (M3) is a block copolymer comprising at least one hydrophobic and at least one hydrophilic block.

15. A surfactant mixture (M) according to claim 14, characterized in that (M3) is a polymer selected from the group of polypropylene oxide-polyethylene oxide block copolymers, polyisobutylene-polyethylene oxide block copolymers and comb polymers with polyethylene oxide side chains and a hydrophobic main chain.

16. surfactant mixture (M) according to any one of claims 10 to 15, characterized in that the mixture further comprises a solvent or a solvent mixture.

17. Use of surfactants according to any one of claims 1 to 6 in washing and

Detergents, ore mining, metalworking, tex- tile manufacturing, leather processing, emulsion stabilization or pesticide formulation.

18. Use of surfactants according to one of claims 1 to 6 for tertiary mineral oil production.

19. Use of surfactant mixtures according to any one of claims 10 to 16 for tertiary mineral oil production.