EP2158186A1

EP2158186A1 - Ionic n-containing compounds

Info

Publication number: EP2158186A1
Application number: EP08773394A
Authority: EP
Inventors: Stefan Busch; Paul Birnbrich; Joachim Meyer; Ronald Klagge
Original assignee: Cognis IP Management GmbH
Current assignee: Cognis IP Management GmbH
Priority date: 2007-06-21
Filing date: 2008-06-12
Publication date: 2010-03-03
Also published as: CN101679289A; WO2008155058A1; JP2010530388A; DE102007028714A1; US20100179260A1

Abstract

Ionic N-containing compounds of the general formula (I), wherein the index n is the number 0 or 1 and the radicals R1 to R5 independently from each other are hydrogen or alkyl, cycloalkyl or aryl radicals with 1 to 25 carbon atoms, wherein the alkyl radicals can be saturated or olefinically unsaturated, straight-chained or branched, and the cycloalkyl radicals can be saturated or olefinically unsaturated, with the following stipulations: (1) if n = 1, at least one of the radials R1 to R5 must contain up to 25 carbon atoms, (2) if n = 0, at least one of the radicals R1, R2, R3 or R5 must contain 8 to 25 carbon atoms, (3) the carbon atoms carrying the radicals R2 and R3 are linked via a C-C-single bond or a C=C-double bond, (4) in the radicals R1 to R5 - if they are alkyl or cycloalkyl radicals - a hydrogen atom linked to a carbon atom can be substituted with an -OH or NH2 group, or an -O-, -COO- or -NH- group can be inserted between two neighboring carbon atoms linked via a C-C single bond, (5) in the radicals R1 to R5 - if they are aryl radicals - a hydrogen atom linked to a carbon atom can be optionally substituted with an alkyl or cycloalkyl group having 1 to 12 carbon atoms, with the stipulation that the following applies to said alkyl or cycloalkyl group: optionally a hydrogen atom linked to a carbon atom can be substituted with an -OH or NH2 group or an -O-, -COO- or -NH- group can be inserted between two neighboring carbon atoms linked via a C-C-single bond, said compounds being suitable as temporary surfactants, particularly for the production of aqueous emulsions or dispersions.

Description

Jonian N-containing compounds'

Field of the invention

The invention relates to ionic N-containing compounds of special structure and their use as temporary surfactants, in particular for the preparation of aqueous emulsions or dispersions.

State of the art

PG Jessop et al. describe in Science 2006, Vol. 313, pp. 958-960 the reversible conversion of amidines and CO ₂ in the presence of water to the corresponding ionic surfactants. This reaction can be reversed by introducing an inert gas (for example nitrogen or argon). Accordingly, the authors refer to this type of ionic surfactants as switchable surfactants, and the activity of such surfactants can be eliminated as needed by eliminating CO ₂ .

Reversible ionic liquids that are liquid at room temperature have recently been described by G. Weiss et al. in Chemistry of Materials 2007, Vol. 19, p. 967-969. Such substances are sometimes referred to as "green solvents." However, the preparation of amidines is not trivial and can be prepared, for example, from the corresponding dimethylketals, which, however, are synthetically difficult to access.

Coalescing agents (also called film-forming aids) are known per se. They are added to aqueous coating materials and cause a film formation of the dispersing agent. th polymer particles to a homogeneous paint film. Their addition is required if the film-forming temperature of the binder is above the application temperature.

Known film-forming aids are: ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, ethylene glycol hexyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol hexyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol phenyl ether, propylene glycol t-butyl ether, 2. 2,4-trimethyl-1,3-pentanediol mono-isobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate.

Recently, water-based coatings have become very up-to-date for environmental reasons. Traditionally, coalescents have been used in substantial quantities in latex coatings, which are based in particular on small particles of synthetic plastics such as polyacrylates. These coalescing agents (also called filming aids) are added to the coatings to improve film formation. The function is based on the fact that the coalescing agent softens the latex particles so that they flow together and form a continuous film. This film has optimal film properties after the evaporation of the water. In the formation of a film, the so-called film-forming temperature is important, in which (or above) the polymer particles flow together to form a film. The usual coalescing agents lower the film forming temperature of the polymer.

Conventional coalescing agents are certain esters and ethers; Known technical standards are the hydroxyester "Texanol" from Eastman (also often called TMB, a 2,2,4-trimethyl-1,3-pentanediol mono-isobutyrate) and "EGBE" from Union Carbide (ethylene glycol monobutyl ether). Description of the invention

In many applications of surfactants, it is desirable to be able to "turn them off" after work, meaning that they are only temporary in nature and can be converted to a non-surfactant form as desired.

It was the object of the present invention to provide novel temporary surfactants. These should be suitable in particular as emulsifiers or dispersants for emulsion polymerization. In addition, the temporary surfactants to be developed should preferably also have the property that the nonionic compounds formed when the temporary surfactant is switched off are suitable as coalescing agents.

Another object of the present invention relates to the preparation of paints and coatings based on aqueous emulsions. Typically, for example, lacquer latexes are produced by emulsion polymerization. While a suitable surfactant is indispensable during the emulsion polymerization and the storage of the aqueous emulsion or dispersion until it is used, so that the polymerization takes place at all and thus the emulsion or dispersion prepared is stabilized, various undesirable characteristics of paint films such as low Water resistance attributed to remaining in the coating surfactant. Another aspect of the present invention relates to the problem of remedy this situation.

Ionic N-containing compounds of the general formula (I),

wherein the index n is the number O or 1 and the radicals R ¹ to R ^{5 are} independently hydrogen or alkyl, cycloalkyl or aryl radicals having 1 to 25 carbon atoms, wherein the alkyl radicals saturated or olefinically unsaturated, straight-chain or branched and the Cycloalkyl radicals may be saturated or olefinically unsaturated, with the following provisos: (1) if n = 1, at least one of R ¹ to R ^{5 must have} 8 to 25 C atoms, (2) if n = 0, at least one of Radicals R ¹ , R ² , R ³ or R ^{5 have} 8 to 25 C atoms, (3) the C atoms carrying the radicals R ² and R ³ are linked via a C-C single bond or a C =C double bond, (4) in the radicals R ¹ to R ⁵ - if these are alkyl or cycloalkyl radicals - may optionally be substituted by a hydrogen atom connected to a C atom to a group -OH or NH ₂ or between two adjacent and via a CC single bond linked C atoms have a group -O-, -COO- or -NH- (5) in the radicals R ¹ to R ⁵ , if these aryl radicals are present, optionally a hydrogen atom connected to a C atom can be substituted by an alkyl or cycloalkyl group having 1 to 12 C atoms, with provided that for these alkyl or cycloalkyl group: optionally, one associated with a C-atom hydrogen atom to a group -OH or NH ₂ may be substituted or between two adjacent and over a C-C single bond linked C-atoms a group -O-, -COO- or -NH- be inserted.

In one embodiment, in formula (I), the subscript n represents the number 1. In one embodiment, in formula (I), the subscript n represents the number O and the carbon atoms bearing the groups R ² and R ³ are represented by a C = C Double bond linked. In a preferred embodiment, in formula (I) the subscript n is the number 0 and the carbon atoms bearing the radicals R ² and R ³ are linked by a C-C single bond. Furthermore, the radical R ^{5 has} the meaning hydrogen. Accordingly, the compounds characterized here have the formula (Ia)

(I-a)

wherein the radicals R ¹ to R ³ independently of one another are hydrogen or alkyl, cycloalkyl or aryl radicals having 1 to 25 C atoms, where the alkyl radicals may be saturated or olefinically unsaturated, straight-chain or branched and the cycloalkyl radicals may be saturated or olefinically unsaturated , with the following provisos: (a) at least one of the radicals R ¹ , R ² or R ³ must have 8 to 25 C atoms, (b) in the radicals R ¹ to R ³ , if these are alkyl or cycloalkyl radicals, optionally a hydrogen atom attached to a C atom is substituted by a group -OH or NH _2, or a group -O-, -COO- or -NH- is inserted between two adjacent C atoms linked via a C-C single bond, ( c) in the radicals R ¹ to R ³ - if these aryl radicals are - optionally a hydrogen atom connected to a C atom may be substituted by an alkyl or cycloalkyl group having 1 to 12 C-atoms, with the proviso that for this alkyl or cycloalkyl group: if appropriate, a hydrogen atom attached to a C atom can be substituted by a group -OH or NH _2, or a group -O-, -COO- or -NH can be substituted between two adjacent carbon atoms linked via a C-C single bond - be inserted.

In formula (Ia), the radical R ¹ is preferably a saturated or olefinically unsaturated alkyl radical having 8 to 25 C atoms. In a very particularly preferred embodiment, in formula (Ia) the radical R ^{1 is} a saturated or olefinically unsaturated alkyl radical having 8 to 25 C atoms and the radicals R ² and R ^{3 are} each hydrogen.

The compounds (I) or (Ia) can be prepared by all methods known to those skilled in the art, for example by reacting N-containing compounds of the general formula (II) or (II-a) with CO ₂ in the presence of water.

In these formulas (II) and (II-a), the definitions and provisos given above for the formulas (I) and (I-a) apply to the radicals.

The compounds (II) can be prepared by all methods known to the person skilled in the art, for example by reacting corresponding 1,2-diamines or 1,3-diamines with fatty acids. Examples of suitable 1,2-diamines are ethylenediamine and propylenediamine. As 1,3-diamine is about 1,3-diaminopropane. Examples of suitable fatty acids are the saturated fatty acids hexanoic acid (caproic acid), heptanoic acid, octanoic acid (caprylic acid), nonanoic acid (pelargonic acid), decanoic acid (capric acid), undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, Tetradecanoic acid (myristic acid), pentadecanoic acid, hexadecanoic acid (palmitic acid), heptadecanoic acid, oxadecanoic acid (stearic acid), nonadecanoic acid, eicosanoic acid (arachic acid), dodecanoic acid (behenic acid) and the olefinically unsaturated fatty acids 10- undecenoic acid, lauroleinic acid, myristoleic acid, palmitoleic acid, petroselinic acid, oleic acid , Elaidic acid, linoleic acid, linolenic acid, elaeostearic acid, gadoleic acid, arachidonic acid, erucic acid, brassidic acid. Preferably, fatty acids of natural origin are used.

Particularly preferred compounds (II) are characterized by the formula (II-b):

In this formula (II-b), R ¹ to R ^{3 have the} same meaning as in the above

Formula (I-a). The compounds (II-a) represent imidazoline derivatives.

Also preferred compounds (II) are characterized by the formula (II-c):

(II-c)

In this formula (II-b), the radicals R ¹ , R ² , R ³ and R ^{5 have the} same meaning as in the above formula (Ia). These compounds can be prepared, for example, from N-substituted 1,2-diamines. A further subject of the invention is the use of the compounds (I) as temporary (switchable) surfactants, in particular as temporary surfactants for the preparation of aqueous emulsions or dispersions and very particularly preferably as temporary surfactants in the emulsion polymerization. In this case, the switching between the ionic surfactant (I) and the resulting by elimination of CO ₂ nonionic compounds (II)

wherein the index n is the number 0 or 1 and the radicals R ¹ to R ^{5 are} independently hydrogen or alkyl, cycloalkyl or aryl radicals having 1 to 25 carbon atoms, wherein the alkyl radicals saturated or olefinically unsaturated, straight-chain or branched and the Cycloalkyl radicals may be saturated or olefinically unsaturated, with the following provisos: (1) if n = 1, at least one of R ¹ to R ^{5 must have} 8 to 25 C atoms, (2) if n = 0, at least one of Radicals R, R, R or R ^{5 have} 8 to 25 C atoms, (3) the C atoms carrying the radicals R ² and R ³ are linked via a C-C single bond or a C =C double bond, (4) in the radicals R ¹ to R ⁵ , if these are alkyl or cycloalkyl radicals, it is optionally possible for a hydrogen atom linked to a C atom to be substituted by a group -OH or NH _2, or between two adjacent carbonyls linked via a C-C single bond. Atoms a group -O-, -COO- or -NH- used (b) in radicals R ¹ to R ⁵ , if these aryl radicals are present, it is optionally possible for a hydrogen atom connected to a C atom to be substituted by an alkyl or cycloalkyl group having from 1 to 12 C atoms, with Stipulation that for this Alkyl or cycloalkyl group: if appropriate, a hydrogen atom attached to a carbon atom can be substituted by a group -OH or NH _2, or a group -O-, -COO- or - is attached between two adjacent carbon atoms linked via a single carbon-carbon bond NH- inserted, by means of an inert gas, for example nitrogen or argon, causes.

Particular preference is given in this connection to the compounds (Ia) defined above, from which the above-defined nonionic compounds (II-a) are formed by cleavage of CO ₂ .

The compounds (I) to be used according to the invention as temporary surfactants can be used in pure form or in the form of mixtures with one another. If desired, it is also possible to use the compounds (I) in combination with other surfactants.

Another subject of the invention is a process for the preparation of coatings based on aqueous polymer or latex dispersions, which comprises preparing the aqueous polymer or latex dispersions using the above-defined temporary surfactants (I) as emulsifiers and the temporary surfactants (I) when applying the aqueous polymer or latex dispersions by cleavage of CO ₂ in the above-defined non-surfactant compounds (II) transferred, which then serve as a coalescing agent.

The term coalescing agents (also referred to in the literature as filming assistants or film-forming aids) is to be understood in the sense which is well-known to those skilled in the art and described above.

With regard to the nature of the polymer or latex particles present in the aqueous dispersions, there are no particular restrictions. It can thus all the One skilled in the art for coating purposes relevant known polymers and Copolyme- ren used.

Incidentally, the aqueous dispersions may contain further additives and additives known to those skilled in the art, depending on the desired application or the type of coating.

The aqueous dispersions containing temporary surfactants (I) to be used according to the invention can, in principle, be applied to any surfaces, for example wood, metal, plastic, glass, paper, concrete, masonry and plasters.

B e i s p e e l e

Example 1 a) Preparation of imidazoline: 150 g (2.5 mol) of ethylenediamine were heated in a 4-necked flask with stirrer, dropping funnel and reflux condenser and under reflux 279 g (1 mol) of oleic acid (Edenor T105, Cognis) dosed within 3 hours. After distillative removal of the water of reaction (18 g) and the excess ethylenediamine, the imidazoline was obtained as a slightly yellow solid. The yellow coloration was due to unseparated ethylenediamine. b) Preparation of the ionic surfactant: By passing CO ₂ into an aqueous suspension of this solid for 4 hours, a colorless suspension was obtained whose surface energy was 30 mJ / m ² . c) Shutdown of the ionic surfactant: Upon introduction of nitrogen for 4 hours, a 2-phase system was formed with a clear aqueous subphase overlaid by a colorless suspension. d) Reactivation of the ionic surfactant: Re-introduction of CO ₂ for about 5 minutes restored the described emulsion, which remained stable for at least 3 weeks.

The synthesis of an imidazoline described in Example 1 and its further reaction with CO ₂ in the presence of water to form the ionic surfactant is described in the following formula scheme:

H r ^NH 2 O AT __ / -N + CO ₂ + H ₂ O j-ti HCO ₃ -

^L NH, ^{+ H0 R ~ T} W * ~ S ^{R "} -CO ₂ V> - ^R

^H H

As illustrated by example 1, the ionic surfactant can be termed temporary, since it can be converted back into the imidazoline by splitting off CO ₂ (switching off the ionic surfactant).

Claims

claims

1. Ionic N-containing compounds of the general formula (I),

wherein the index n is the number 0 or 1 and the radicals R ¹ to R ^{5 are} independently hydrogen or alkyl, cycloalkyl or aryl radicals having 1 to 25 carbon atoms, wherein the alkyl radicals saturated or olefinically unsaturated, straight-chain or branched and the Cycloalkyl radicals may be saturated or olefinically unsaturated, with the following provisos: (1) if n = 1, at least one of R ¹ to R ^{5 must have} 8 to 25 C atoms, (2) if n = 0, at least one of Radicals R ¹ , R ² , R ³ or R ^{5 have} 8 to 25 C atoms, (3) the C atoms carrying the radicals R ² and R ³ are linked via a C-C single bond or a C =C double bond, (4) in the radicals R ¹ to R ⁵ - if these are alkyl or cycloalkyl radicals - may optionally be substituted by a hydrogen atom connected to a C atom to a group -OH or NH ₂ or between two adjacent and via a CC single bond linked C atoms have a group -O-, -COO- or -NH - be inserted (5), in the radicals R ¹ to R ⁵ - if they are aryl radicals - optionally one associated with a C-atom hydrogen atom to an alkyl or cycloalkyl group having 1 to 12 carbon atoms be substituted, with the proviso in that, for this alkyl or cycloalkyl group, it is possible for a hydrogen atom attached to a C atom to be substituted by a group -OH or NH ₂ or a group -O-, to be bonded between two adjacent carbon atoms linked via a C-C single bond. COO or -NH- be inserted.

2. Compounds according to claim 1, wherein in one of the radicals R ¹ to R ⁵ at the terminal carbon atom an OH or NH ₂ group is present.

3. Compounds according to claim 1, wherein the radicals R ² to R ^{4 is} hydrogen, the radical R ^{1 is} an alkyl radical having 8 to 25 carbon atoms and the radical R ^{5 is} a hydroxyethyl group.

4. Compounds (I) according to claim 1, wherein the index n is the number 1.

5. Compounds (I) according to claim 1, wherein the index n is the number 0 and the radicals R ² and R ³ bearing C-atoms are linked via a C = C double bond.

6. Compounds (I) according to claim 1, wherein the index n is the number 0 and the radicals R ² and R ³ bearing C-atoms are linked via a C-C single bond.

7. Compounds (I) according to claim 6, wherein the radical R ^{1 is} a saturated or olefinically unsaturated alkyl radical having 8 to 25 carbon atoms.

8. Compounds (I) according to claim 7, wherein the radicals R ² , R ³ and R ^{5 are} each hydrogen.

9. Use of the compounds (I)

(I) wherein the index n is the number O or 1 and the radicals R ¹ to R ⁵ independently of one another are hydrogen or alkyl, cycloalkyl or aryl radicals having 1 to 25 carbon atoms, where the alkyl radicals are saturated or olefinically unsaturated, straight-chain or branched and the cycloalkyl radicals may be saturated or olefinically unsaturated, with the following provisos: (1) if n = 1, at least one of the radicals R ¹ to R ^{5 must have} 8 to 25 C atoms, (2) if n = 0 at least one of the radicals R ¹ , R ² , R ³ or R ^{5 have} 8 to 25 carbon atoms, (3) the radicals R ² and R ³ bearing C atoms are linked via a C-C single bond or a C = C double bond, (4) in the radicals R ¹ to R ⁵ - if these are alkyl or cycloalkyl radicals - optionally one with a C Atom connected to a group -OH or NH _{2 be} substituted or between two adjacent and linked via a C-C single bond carbon atoms, a group -O-, -COO- or -NH- be inserted, (5) in the radicals R ¹ to R ⁵ , if these aryl radicals, may optionally be substituted by a hydrogen atom attached to a C atom to an alkyl or cycloalkyl group having from 1 to 12 C atoms, with the proviso that for this alkyl or cycloalkyl group: optionally, a hydrogen atom attached to a carbon atom may be substituted by a group -OH or NH _2, or a group -O-, -COO- or -NH- may be interposed between two adjacent carbon atoms linked via a carbon-carbon single bond temporary (switchable) Surfactants.

10. Use of the compounds (I) according to claim 9 as temporary surfactants for the preparation of aqueous emulsions or dispersions.

11. Use of the compounds (I) according to claim 9 as temporary surfactants in the emulsion polymerization.

12. Use according to any one of claims 9 to 11, wherein the switching between the ionic surfactant (I) and the resulting by elimination of CO ₂ nonionic compound (II)

(H) wherein the index n is the number O or 1 and the radicals R ¹ to R ^{5 are} independently hydrogen or alkyl, cycloalkyl or aryl radicals having 1 to 25 carbon atoms where the alkyl radicals are saturated or olefinically unsaturated, straight-chain or branched and the cycloalkyl radicals may be saturated or olefinically unsaturated, with the following provisos: (1) if n = 1, at least one of the radicals R ¹ to R ^{5 must have} 8 to 25 C (2) if n = 0, at least one of the radicals R ¹ , R ² , R ³ or R ^{5 must have} 8 to 25 C atoms, (3) the C atoms carrying the radicals R ² and R ³ are linked via a CC single bond or a C = C double bond, (4) in the radicals R ¹ to R ⁵ - if these are alkyl or cycloalkyl radicals - optionally a hydrogen atom bonded to a C atom to a group -OH or NH _{2 may be} substituted or between two adjacent C atoms linked via a C-C single bond, a group -O-, -COO- or -NH- be inserted, (5) in the radicals R ¹ to R ⁵ - if these Aryl radicals are - optionally a hydrogen atom linked to a C atom to a Substituted alkyl or cycloalkyl group having 1 to 12 carbon atoms, with the proviso that for this alkyl or cycloalkyl group applies: optionally, a hydrogen atom connected to a C atom substituted for one group -OH or NH ₂ or between two adjacent and C-atoms linked via a C-C single bond are a group -O-, -COO- or -NH- inserted, by means of an inert gas.

13. A process for the preparation of coatings based on aqueous polymer or latex dispersions, characterized in that the aqueous Polymerbzw. Latex dispersions using temporary surfactants (I)

(I) wherein the index n is the number O or 1 and the radicals R ¹ to R ^{5 are} independently hydrogen or alkyl, cycloalkyl or aryl radicals having 1 to 25 carbon atoms where the alkyl radicals are saturated or olefinically unsaturated, straight-chain or branched and the cycloalkyl radicals may be saturated or olefinically unsaturated, with the following provisos: (1) if n = 1, at least one of the radicals R ¹ to R ^{5 must have} 8 to 25 C (2) if n = 0, at least one of the radicals R ¹ , R ² , R ³ or R ^{5 must have} 8 to 25 C atoms, (3) the C atoms carrying the radicals R ² and R ³ are linked via a CC single bond or a C = C double bond, (4) in the radicals R ¹ to R ⁵ - if these are alkyl or cycloalkyl radicals - optionally a hydrogen atom bonded to a C atom to a group -OH or NH _{2 may be} substituted or between two adjacent C atoms linked via a C-C single bond, a group -O-, -COO- or -NH- be inserted, (5) in the radicals R ¹ to R ⁵ - if these Aryl radicals are - optionally a hydrogen atom linked to a C atom to a Substituted alkyl or cycloalkyl group having 1 to 12 carbon atoms, with the proviso that for this alkyl or cycloalkyl group applies: optionally, a hydrogen atom connected to a C atom substituted for one group -OH or NH ₂ or between two adjacent and C atoms linked via a C-C single bond are a group -O-, -COO- or -NH- inserted, as emulsifiers and the temporary surfactants (I) when applying the aqueous polymer or latex dispersions Cleavage of CO ₂ into the non-surfactant compounds (II)

(H) wherein the subscript n is the number O or 1 and the radicals R ¹ to R ⁵ independently of one another are hydrogen or alkyl, cycloalkyl or aryl radicals having 1 to 25 C atoms, where the alkyl radicals are saturated or olefinically unsaturated, straight-chain or branched and the cycloalkyl radicals can be saturated or olefinically unsaturated, with the following provisos: (1) if n = 1, at least one of the radicals R ¹ to R ^{5 must have} 8 to 25 C atoms, (2) if n = 0 at least one of the radicals R ¹ , R ² , R ³ or R ^{5 must have} 8 to 25 C atoms, (3) the C atoms carrying the radicals R ² and R ^{3 are} bonded via a C-C single bond or a C = C - Double bond linked, (4) in the radicals R ¹ to R ⁵ - if these are alkyl or cycloalkyl radicals - optionally a hydrogen atom connected to a carbon atom may be substituted by a group -OH or NH ₂ or between two adjacent and on a C-C single bond linked C atoms may be a group -O-, -COO- or -NH- inserted, (5) in the radicals R ¹ to R ⁵ may - if these aryl radicals - optionally one connected to a carbon atom Hydrogen atom be substituted by an alkyl or cycloalkyl group having 1 to 12 carbon atoms, with the Maßg abe, that for these alkyl or cycloalkyl group: optionally, a connected to a C-atom hydrogen atom to a group -OH or NH substituted ₂ or between two adjacent and over a C-C single bond linked C-atoms a group -O-, -COO- or -NH- be inserted, which then serve as a coalescing agent.

14. The method according to claim 13, wherein the removal of CO ₂ from the temporary surfactants (I) by means of an inert gas.

15. The method of claim 14, wherein the inert gas is nitrogen or argon.