Organomodified polysiloxanes and their use for defoaming fuels

Abstract

Disclosed are organomodified polysiloxanes, compositions, in particular fuel compositions, that include these organomodified polysiloxanes, and the use of the organomodified polysiloxanes for the defoaming of fuels.

Claims

1. An organomodified polysiloxane of formula (I), ##STR00008## in which R in each case independently is selected from the group consisting of hydrocarbon radicals; R.sup.1 in each case independently is selected from the group consisting of R, R.sup.2 and R.sup.3; R.sup.2 in each case independently is selected from the group consisting of polyether radicals of formula (II),
—Z.sup.1(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.6).sub.e(OC.sub.4H.sub.8).sub.f(OC.sub.2H.sub.3Ph).sub.gOR.sup.4  formula (II), Z.sup.1 in each case independently is selected from the group consisting of divalent aliphatic hydrocarbon radicals having 2 to 10 carbon atoms; Ph is a phenyl radical; R.sup.4 in each case independently is selected from the group consisting of a hydrogen radical, alkyl radicals having 1 to 4 carbon atoms and acyl radicals having 1 to 4 carbon atoms; R.sup.3 in each case independently is selected from the group consisting of radicals of formula (III), ##STR00009## Z.sup.2 in each case independently is selected from the group consisting of divalent aliphatic hydrocarbon radicals having 2 to 10 carbon atoms; R.sup.5 in each case independently is selected from the group consisting of a hydrogen radical, a hydroxy group, alkyl radicals having 1 to 4 carbon atoms, and alkoxy radicals having 1 to 4 carbon atoms, with the proviso that at least one radical R.sup.5 is a hydroxy group; wherein: a=50 to 960; b=4 to 85; c=0.5 to 10; d=0 to 60; e=0 to 60; f=0; g=0 to 60; with the proviso that: d+e+f+g=1 to 60; and a /(b+c) is greater than 7.

2. The organomodified polysiloxane according to claim 1, wherein a+b+c+2=60 to 1000.

3. The organomodified polysiloxane according to claim 1, wherein g=0.

4. The organomodified polysiloxane according to claim 1, wherein a number-average molecular weight M.sub.N of the polyether radical R.sup.2 is from 500 g/mol to 1400 g/mol.

5. The organomodified polysiloxane according to claim 1, wherein a proportion by mass of the oxyethylene groups (OC.sub.2H.sub.4), based on a total mass of all oxyalkylene groups, is more than 50%.

6. A composition, comprising: (a) at least one defoamer selected from the group consisting of organomodified polysiloxanes of formula (I) according to claim 1; (b) at least one demulsifier selected from the group consisting of acetylenediols, acetylenediol polyethers, fatty alcohol alkoxylates, and organomodified polysiloxanes that differ from the organomodified polysiloxanes of formula (I); (c) optionally at least one solvent selected from the group consisting of fatty alcohols having 6 to 11 carbon atoms.

7. The composition according to claim 6, wherein component (a) is present at a proportion by mass of 20% to 80%; and component (b) is present at a proportion by mass of 1% to 25%; based on the total mass of the composition.

8. The composition according to claim 6, wherein components (a) and (b) are present in a ratio by weight of (a) to (b) of from 2:1 to 15:1.

9. A fuel composition, comprising: diesel fuel, and at least one organomodified polysiloxane according to claim 1.

10. The fuel composition according to claim 9, wherein a proportion by mass of the at least one organomodified polysiloxane, based on a total mass of the fuel composition, is from 1 ppm to 40 ppm.

11. The fuel composition according to claim 9, wherein a proportion by mass of silicon, based on a total mass of the fuel composition, is from 0.2 ppm to 2 ppm.

12. The fuel composition according to claim 9, wherein the diesel fuel comprises biofuel, and wherein a proportion by mass of biofuel, based on a total mass of the fuel composition, is at least 4%.

13. The fuel composition according to claim 9, wherein the diesel fuel comprises biofuel, and wherein the biofuel is selected from the group consisting of fatty acid methyl esters, hydrogenated vegetable oils, hydrocarbons from biomass-to-liquid processes, and hydrocarbons from gas-to-liquids processes.

14. A method of reducing foam formation in a fuel, comprising: adding the organomodified polysiloxane according to claim 1 to a fuel.

15. The organomodified polysiloxane according to claim 1, wherein the hydrocarbon radicals of R have 1 to 10 carbon atoms.

16. The organomodified polysiloxane according to claim 1, wherein R and/or R.sup.1 in each case is methyl.

17. The organomodified polysiloxane according to claim 1, wherein R.sup.2 in each case independently is formula (IIa),
—Z.sup.1(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.6).sub.eOR.sup.4  formula (IIa),
or formula (IIb),
—(CH.sub.2).sub.3(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.6).sub.eOH  formula (IIb).

18. The organomodified polysiloxane according to claim 1, wherein divalent aliphatic hydrocarbon radicals Z.sup.1 in each case independently has 3 to 4 carbon atoms.

19. The organomodified polysiloxane according to claim 1, wherein R.sup.4 in each case independently is selected from the group consisting of a hydrogen radical, a methyl radical and an acetyl radical.

20. The organomodified polysiloxane according to claim 1, wherein the divalent aliphatic hydrocarbon radicals of Z.sup.2 in each case independently have 3 to 4 carbon atoms.

21. The organomodified polysiloxane according to claim 1, wherein a=100 to 190; b=8 to 20; c=0.8 to 8; d=5 to 20; e=1 to 30; f=0; and g=0 to 10; with the proviso that: d+e+f+g=5 to 30; and a/(b+c) is from 7 to 13.

22. The organomodified polysiloxane according to claim 2, wherein a+b+c+2=90 to 220.

23. The organomodified polysiloxane according to claim 3, wherein Z.sup.1=—(CH.sub.2).sub.3— and optionally, R.sup.4=H.

24. The organomodified polysiloxane according to claim 4, wherein the number-average molecular weight M.sub.N of the polyether radical R.sup.2 is from 600 g/mol to 1200 g/mol.

25. The organomodified polysiloxane according to claim 5, wherein the proportion by mass of the oxyethylene groups (OC.sub.2H.sub.4), based on the total mass of all oxyalkylene groups, is 60% to 90%.

26. The composition according to claim 7, wherein the proportion by mass of component (a) is 30% to 70% and the proportion by mass of component (b) is 2% to 20%; based on the total mass of the composition.

27. The composition according to claim 8, wherein the ratio by weight of (a) to (b) is from 3:1 to 13:1.

28. A fuel composition, comprising: diesel fuel, and at least one composition according to claim 6.

29. The fuel composition according to claim 10, wherein the proportion by mass of the at least one organomodified polysiloxane, based on the total mass of the fuel composition, is from 2 ppm to 25 ppm.

30. The fuel composition according to claim 11, wherein the proportion by mass of silicon, based on the total mass of the fuel composition, is from 0.4 ppm to 1.5 ppm.

31. The fuel composition according to claim 12, wherein the proportion by mass of biofuel, based on the total mass of the fuel composition, is from 4% to 20%.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The subject-matter of the invention is described by way of example below but without any intention that the invention be restricted to these illustrative embodiments. Where ranges, general formulae or classes of compounds are specified below, these are intended to encompass not only the corresponding ranges or groups of compounds which are explicitly mentioned but also all subranges and subgroups of compounds which can be obtained by extracting individual values (ranges) or compounds. Where documents are cited within the context of the present description, the entire content thereof is intended to be part of the disclosure of the present invention.

(2) Where average values are reported hereinafter, these values are numerical averages unless stated otherwise. Where measurement values, parameters or material properties determined by measurement are reported hereinafter, these are, unless otherwise stated, measurement values, parameters or material properties which are measured at 25° C. and also preferably at a pressure of 101325 Pa (standard pressure) and more preferably additionally at a relative atmospheric humidity of 50%. The number-average molecular weight M.sub.N is determined by means of gel permeation chromatography (GPC) as per standard DIN 55672:2018, preferably as per standard DIN 55872-1:2016.

(3) Where numerical ranges in the form “X to Y” are reported hereinafter, where X and Y represent the limits of the numerical range, this is synonymous with the statement “from at least X up to and including Y”, unless otherwise stated. Statements of ranges thus include the range limits X and Y, unless stated otherwise.

(4) Wherever molecules/molecule fragments have one or more stereocentres or can be differentiated into isomers on account of symmetries or can be differentiated info isomers on account of other effects, for example restricted rotation, all possible isomers are included by the present invention.

(5) The formulae (I), (II), (IIa) and (IIb) below describe compounds or radicals that are constructed from repeating units, for example repeating fragments, blocks or monomer units, and can have a molar mass distribution. The frequency of the repeating units is reported by indices. The indices used in the formulae should be regarded as statistical averages (numerical averages). The indices used and also the value ranges of the reported indices are thus understood to be averages of the possible statistical distribution of the structures that are actually present and/or mixtures thereof. The various fragments or repeating units in the formulae (I), (II), (IIa) and (IIb) below may be distributed statistically. Statistical distributions are of blockwise construction with any desired number of blocks and with any desired sequence or are subject to a randomized distribution; they may also have an alternating construction or else form a gradient over the chain, where one is present; in particular they can also form all mixed forms in which groups with different distributions may optionally follow one another. Where, within the context of the present invention, compounds, such as for example organomodified polysiloxanes, are described which can have different units multiple times, then these can occur in these compounds in an unordered manner, for example statistically distributed, or in an ordered manner. The information on the number of units in such compounds is to be understood as an average (numerical average) averaged over all corresponding compounds. Specific embodiments may lead to restrictions of the statistical distributions as a result of the embodiment. There is no change in the statistical distribution for all regions unaffected by the restriction.

(6) The present invention firstly provides an organomodified polysiloxane of general formula (I),

(7) ##STR00006##

(8) in which R in each case independently is selected from the group consisting of hydrocarbon radicals, preferably having 1 to 10 carbon atoms, particularly preferably methyl; R.sup.1 in each case independently is selected from the group consisting of R, R.sup.2 and R.sup.3, preferably R, particularly preferably methyl; R.sup.2 in each case independently is selected from the group consisting of polyether radicals of general formula (II),
—Z.sup.1(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.6).sub.e(OC.sub.4H.sub.8).sub.f(OC.sub.2H.sub.3Ph).sub.gOR.sup.4  formula (II), preferably of general formula (IIa),
—Z.sup.1(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.6).sub.eOR.sup.4  formula (IIa), particularly preferably of general formula (IIb),
—(CH.sub.2).sub.3(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.6).sub.eOH  formula (IIb); Z.sup.1 in each case independently is selected from the group consisting of divalent aliphatic hydrocarbon radicals having 2 to 10, preferably 3 to 4, particularly preferably 3, carbon atoms; Ph is a phenyl radical; R.sup.4 in each case independently is selected from the group consisting of a hydrogen radical, alkyl radicals having 1 to 4 carbon atoms and acyl radicals having 1 to 4 carbon atoms; preferably is selected from the group consisting of a hydrogen radical, a methyl radical and an acetyl radical; particularly preferably is a hydrogen radical, R.sup.3 in each case independently is selected from the group consisting of radicals of general formula (III),

(9) ##STR00007## Z.sup.2 in each case independently is selected from the group consisting of divalent aliphatic hydrocarbon radicals having 2 to 10, preferably 3 to 4, particularly preferably 3, carbon atoms; R.sup.5 in each case independently is selected from the group consisting of a hydrogen radical, a hydroxy group, alkyl radicals having 1 to 4 carbon atoms and alkoxy radicals having 1 to 4 carbon atoms, with the proviso that at least one radical R.sup.5 is a hydroxy group;

(10) where:

(11) a=50 to 960, preferably 80 to 200, particularly preferably 100 to 190;

(12) b=4 to 85, preferably 6 to 25, particularly preferably 8 to 20;

(13) c=0.5 to 10, preferably 0.8 to 8, particularly preferably 1 to less than 4.5;

(14) d=0 to 60, preferably 5 to 20, particularly preferably 10 to 15;

(15) e=0 to 60, preferably 1 to 30, particularly preferably 2 to 5;

(16) f=0 to 60, preferably 0 to 10, particularly preferably 0;

(17) g=0 to 60, preferably 0 to 10, particularly preferably 0;

(18) with the proviso that:

(19) d+e+f+g=1 to 60, preferably 5 to 30, particularly preferably 10 to 20; and

(20) a/(b+c) is greater than 7, preferably >7 to 13, particularly preferably 8 to 12, especially 9 to 11.

(21) The inventive organomodified polysiloxanes of formula (I) may in particular be used as defoamers for fuel compositions that comprise diesel fuel or heating oil and preferably biofuel.

(22) The following preferably applies for the organomodified polysiloxane of formula (I): a-f-b+c+2=60 to 1000, preferably 90 to 220, particularly preferably 130 to 170. The sum (a+b+c+2) here represents the number of silicon atoms of the organomodified polysiloxane/the chain length of the organomodified polysiloxane.

(23) The siloxane units [R.sub.2SiO], [RR.sup.2SiO] and [RR.sup.3SiO] and also the oxyalkylene groups (OC.sub.2H.sub.4), (OC.sub.3H.sub.6), (OC.sub.4H.sub.8) and (OC.sub.2H.sub.3Ph) of the organomodified polysiloxanes of formula (I) can be arranged as desired. They can thus be arranged blockwise with any desired number of blocks and any desired sequence or be statistically distributed; they can also be arranged in an alternating manner, or form a gradient along the chain with respect to their frequency, or have, along the chain, a distribution that results from a possible difference in reactivity of the precursors or that is due to thermodynamic equilibria.

(24) The oxyalkylene groups of the polyether radical R.sup.2 are derived from corresponding monomeric alkylene oxides, that is to say (OC.sub.2H.sub.4) from ethylene oxide, (OC.sub.3H.sub.6) from propylene oxide, (OC.sub.4H.sub.8) from butylene oxide and (OC.sub.2H.sub.3Ph) from styrene oxide. The polyethers on which the polyether radicals R.sup.2 are based may be obtained by addition of the monomeric alkylene oxides onto a starter alcohol, preferably allyl alcohol. The prior art discloses the preparation of such polyethers by alkaline catalysis, for example with potassium or sodium methoxide, or by double metal cyanide catalysis (DMC catalysis) with double metal cyanide catalysts (DMC catalysts). The polyether radical R.sup.2 is preferably a hydroxy-functional polyether radical.

(25) The polyoxyalkylene chain of the polyether radical R.sup.2 is linked via a divalent radical Z.sup.1 to the polysiloxane chain of the organomodified polysiloxane of general formula (I). The divalent radical Z.sup.1 is preferably in each case independently selected from the group consisting of divalent alkylene radicals of the formula —(CH.sub.2).sub.n— where n=2 to 10, preferably 3 to 4, particularly preferably 3. Z.sup.1 is preferably selected here from divalent ethylene, propylene, 1-methylpropylene and 1,1-dimethylpropylene radicals, especially preferably —CH.sub.2CH.sub.2CH.sub.2—.

(26) The polyether radical R.sup.2 preferably does not have any groups derived from butylene oxide, that is to say no oxybutylene groups (OC.sub.4H.sub.8). Thus, the following preferably applies for the organomodified polysiloxane of general formula (I): f=0. It is also preferred that the polyether radical R.sup.2 does not have any groups derived from styrene oxide, that is to say oxyalkylene groups of the formula (OC.sub.2H.sub.3Ph). Thus, the following preferably applies for the organomodified polysiloxane of general formula (I): g=0. It is additionally preferred that the polyether radical R.sup.2 does not have any oxyalkylene units that are derived from butylene oxide or styrene oxide. It is thus preferred that the following applies for the organomodified polysiloxane of general formula (I): f=0 and g=0. It is further preferred that the polyether radical R.sup.2 is additionally derived from allyl alcohol. Thus, further preferably, the following applies: f=0 and g=0 and Z.sup.1=—(CH.sub.2).sub.3—. In addition, it is particularly preferred that the polyether radical R.sup.2 is terminated by a hydroxyl group. It is thus particularly preferred that the following applies: f=0 and g=0 and Z.sup.1=—(CH.sub.2).sub.3— and R.sup.4=H.

(27) The number-average molecular weight M.sub.N of the polyether radical R.sup.2 is preferably from 500 g/mol to 1400 g/mol, more preferably from 600 g/mol to 1200 g/mol, particularly preferably from 700 g/mol to 900 g/mol. The number-average molecular weight M.sub.N of the polyether radical R.sup.2 is identical here to the number-average molecular weight M.sub.N of the corresponding monounsaturated polyether on which the polyether radical R.sup.2 is based.

(28) It is moreover preferred that the polyether radical R.sup.2, calculated without Z.sup.1 and calculated without OR.sup.4, has a molar mass M(PE) of from 450 g/mol to 1350 g/mol, preferably of from 550 g/mol to 1150 g/mol, particularly preferably of from 650 g/mol to 850 g/mol. The molar mass M(PE) is calculated here according to the equation M(PE)=44 g/mol*d+58 g/mol*e+72 g/mol*f+20120 g/mol*g, where d, e, f and g refer to the indices in formula (II), (IIa) and (IIb), where for formula (IIa) and (IIb) accordingly f=0 and g=0.

(29) It is preferred that the proportion by mass of the oxyethylene groups (OC.sub.2H.sub.4), based on the total mass of all oxyalkylene groups, is more than 50%, preferably 60% to 90%, particularly preferably 2570% to 80%.

(30) The proportion by mass of the oxypropylene groups (OC.sub.3H.sub.6), based on the total mass of all oxyalkylene groups, is preferably less than 50%, more preferably from 10% to 40%, particularly preferably from 20% to 30%.

(31) It is moreover preferred that the proportion by mass of the oxybutylene groups (OC.sub.4H.sub.6), based on the total mass of all oxyalkylene groups, is less than 20%, preferably less than 10%, particularly preferably 0%.

(32) It is moreover preferred that the proportion by mass of the oxyalkylene groups derived from styrene oxide (OC.sub.2H.sub.3Ph), based on the total mass of all oxyalkylene groups, is less than 20%, preferably less than 10%, particularly preferably 0%.

(33) With preference, the proportion by mass of the oxyethylene groups (OC.sub.2H.sub.4), based on the total mass of all oxyalkylene groups, is at least 50%, preferably 80% to 90%, particularly preferably 70% to 80%, the proportion by mass of the oxypropylene groups (OC.sub.3H.sub.6), based on the total mass of all oxyalkylene groups, is at most 50%, preferably 10% to 40%, particularity preferably 20% to 30%, the proportion by mass of the oxybutylene groups (OC.sub.4H.sub.8), based on the total mass of all oxyalkylene groups, is 0% and the proportion by mass of the oxyalkylene groups derived from styrene oxide (OC.sub.2H.sub.3Ph) is 0%, with the proviso that the sum of the proportion by mass of the oxyethylene groups (OC.sub.2H.sub.4) and of the oxypropylene groups (OC.sub.3H.sub.6), based on the total mass of all oxyalkylene groups, together make 100%.

(34) Besides the polyether radical R.sup.2, the organomodified polysiloxane of formula (I) has an aromatic radical R.sup.3. This radical R.sup.3 preferably has, as divalent radical Z.sup.2, a radical selected from the group consisting of divalent alkylene radicals of the formula —(CH.sub.2).sub.n— where n=2 to 10, preferably 3 to 4, particularly preferably 3. The radical R.sup.3 is preferably selected from a phenol radical or phenol derivative radicals. The radical R.sup.3 therefore preferably has exactly one hydroxyl group. Particularly preferred radicals R.sup.3 are derived from eugenol or allylphenol, especially from o-allylphenol.

(35) The following applies for a radical R.sup.3 derived from eugenol: Z.sup.2 is a propylene radical —(CH.sub.2).sub.3—; three radicals R.sup.5 are hydrogen radicals, one radical R.sup.5 is a hydroxyl group and one radical R.sup.5 is a methoxy group, that is to say: R.sup.3=—(CH.sub.2).sub.3[C.sub.5H.sub.3(OCH.sub.3)]OH.

(36) The following applies for a radical R.sup.3 derived from allylphenol: Z.sup.2 is a propylene radical —(CH.sub.2).sub.3—; four radicals R.sup.5 are hydrogen radicals and one radical R.sup.5 is a hydroxyl group, that is to say: R.sup.3=—(CH.sub.2).sub.3(C.sub.6H.sub.4)OH.

(37) The organic radicals R.sup.2 and R.sup.3 may be introduced into the molecule of the polysiloxane by addition of appropriate unsaturated precursors (e.g. allyl or vinyl compounds) onto SIH groups of a corresponding SiH-functional polysiloxane in the presence of a hydrosilylation catalyst, for example according to the method of U.S. Pat. No. 5,334,227 (A) or as described in “Silicones: chemistry and technology”, Vulkan-Verlag, Essen. The organomodified polysiloxanes of formula (I) are therefore preferably prepared by means of hydrosilylation in the manner known to the person skilled in the art. This involves using known methods to react the corresponding hydrosilyl-functional polysiloxanes with olefinically unsaturated compounds. The olefinically unsaturated compounds are olefinically unsaturated polyethers, preferably allyl polyethers, and olefinically unsaturated phenol derivatives, preferably 2-allylphenol and/or eugenol. The hydrosilylation reaction here is preferably catalysed with the aid of the platinum group catalysts familiar to the person skilled in the art, more preferably with the aid of Karstedt catalysts.

(38) The polysiloxane chain of the organomodified polysiloxane of formula (I) has pendent and optionally also terminal (i.e. in α,ω position) radicals selected from the group consisting of R.sup.2 and R.sup.3. The polysiloxane chain of the organomodified polysiloxane preferably has only pendent radicals selected from the group consisting of R.sup.2 and R.sup.3. There are, in particular, economic reasons for this.

(39) The degree of branching of the organomodified polysiloxane can be indicated by the quotient (b+c)/(a+b+c+2). Preferably: (b+c)/(a+b+c+2)=0.05 to 0.30, more preferably 0.07 to 0.15, particularly preferably 0.09 to 0.11,

(40) Through the choice of the radicals R, R.sup.1, R.sup.2 and R.sup.3 and also the quantitative ratios thereof, it is possible to optimally adjust the defoaming action and cold stability of the defoamer.

(41) The following preferably applies for the organomodified polysiloxane of general formula (I): R in each case independently is selected from the group consisting of hydrocarbon radicals having 1 to 10 carbon atoms, particularly preferably methyl; R.sup.1 is a radical R, particularly preferably methyl; R.sup.2 in each case independently is selected from the group consisting of polyether radicals of general formula (IIa),
—Z.sup.1(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.6).sub.eOR.sup.4  formula (IIa), particularly preferably of general formula (IIb),
—(CH.sub.2).sub.3(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.8).sub.eOH  formula (IIb); Z.sup.1 in each case independently is selected from the group consisting of divalent aliphatic hydrocarbon radicals having 3 to 4, particularly preferably 3, carbon atoms; R.sup.4 in each case independently is selected from the group consisting of a hydrogen radical, a methyl radical and an acetyl radical; particularly preferably is a hydrogen radical; Z.sup.2 in each case independently is selected from the group consisting of divalent aliphatic hydrocarbon radicals having 3 to 4, particularly preferably 3, carbon atoms; R.sup.5 in each case independently is selected from the group consisting of a hydrogen radical, a hydroxy group, alkyl radicals having 1 to 4 carbon atoms and alkoxy radicals having 1 to 4 carbon atoms, with the proviso that at least one radical R.sup.5 is a hydroxy group; a=preferably 80 to 200, particularly preferably 100 to 190; b=preferably 6 to 25, particularly preferably 8 to 20; c=preferably 0.8 to 8, particularly preferably 1 to less than 4.5; d=preferably 5 to 20, particularly preferably 10 to 15; e=preferably 1 to 30, particularly preferably 2 to 5; f=preferably 0 to 10, particularly preferably 0; g=preferably 0 to 10, particularly preferably 0; with the proviso that: d+e=5 to 30, particularly preferably 10 to 20; and a/(b+c)=7 to 13, particularly preferably 8 to 12, especially 9 to 11.

(42) The following applies for particularly preferred organomodified polysiloxanes of general formula (I):

(43) R=methyl;

(44) R.sup.1=methyl;

(45) R.sup.2=—(CH.sub.2).sub.3(OC.sub.2H.sub.4).sub.d(OC.sub.3H.sub.6).sub.eOH;

(46) R.sup.3=—(CH.sub.2).sub.3(C.sub.8H.sub.4)OH or —(CH.sub.2).sub.3[C.sub.6H.sub.3(OCH.sub.3)]OH, especially —(CH.sub.2).sub.3(C.sub.6H.sub.4)OH;

(47) a=100 to 190;

(48) b=8 to 20;

(49) c=1 to less than 4.5;

(50) d=10 to 15;

(51) e=2 to 5;

(52) f=0;

(53) g=0;

(54) with the proviso that:

(55) d+e=10 to 20; and

(56) a/(b+c)=8 to 12, especially 9 to 11.

(57) The inventive organomodified polysiloxanes of formula (I) can be added directly to the fuel as defoamer. However, it is preferred in practice to add the defoamer to the so-called additive package. The additive package essentially contains a detergent, a demulsifier/dehazer and a cetane number improver. In order to improve the compatibility of the organomodified polysiloxane of formula (i) with the additive package, it may be advantageous to use the defoamer in a mixture with 2-ethylhexanol or glycols or aromatic-system-containing solvents.

(58) The invention therefore further relates to a composition comprising the components: (a) at least one defoamer selected from the group consisting of organomodified polysiloxanes of formula (I); (b) at least one demulsifier selected from the group consisting of acetylenediols, acetylenediol polyethers, fatty alcohol alkoxylates and polyethersiloxanes that differ from the organomodified polysiloxanes of formula (I); (c) optionally at least one solvent selected from the group consisting of fatty alcohols having 8 to 11 carbon atoms.

(59) The acetylenediols/acetylenediol polyethers of component (b) are preferably selected from compounds of the general formula R′R″(R′″O)C—C≡C—C(OR′″)R″R.sup.1;

(60) where R′ and R″ in each case are independently selected from the group consisting of linear and branched, substituted and unsubstituted alkyl, aryl and alkoxyalkyl radicals having 1 to 10 carbon atoms; and where

(61) R′″ in each case independently is selected from the group consisting of a hydrogen atom and polyether radicals.

(62) The polyether radicals are obtainable here by reacting an appropriate alkylenediol R′R″(HO)C—C≡C—C(OH)R″R′ with alkylene oxides selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide. R′″ is preferably a polyether radical of the formula —(CH.sub.2CH.sub.2O).sub.n—H where n=1 to 60.

(63) The fatty alcohol alkoxylates of component (b) are preparable by alkoxylation, that is reaction with ethylene oxide (fatty alcohol ethoxylates, FAEO), propylene oxide (FAPO) or butylene oxide, but preferably ethoxylation of linear or branched, preferably branched, fatty or oxo alcohols in the presence of basic or acidic catalysts at temperatures of 120-200° C. and pressures of 1-10 bar. The fatty alcohols used here are preferably selected from the group consisting of fatty alcohols having 8 to 16 carbon atoms. These fatty alcohols are preferably saturated alcohols, particularly preferably saturated primary alcohols selected from the group consisting of C.sub.6H.sub.13OH, C.sub.7H.sub.15OH, C.sub.8H.sub.17OH, C.sub.9H.sub.19OH, C.sub.10H.sub.21OH, C.sub.11H.sub.23OH, C.sub.12H.sub.25OH, C.sub.13H.sub.27OH, C.sub.14H.sub.29OH, C.sub.15H.sub.31OH, C.sub.16H.sub.33OH. The fatty alcohols are adjusted to the desired polarity by the alkoxylation. A suitable measure for the polarity is the HLB value, which is preferably determined by the method of Griffin (W. C. Griffin: Classification of surface active agents by HLB, J. Soc. Cosmet. Chem. 1 1949, pp 311-326). The HLB value of the fatty alcohol alkoxylates is preferably between 5 and 10.

(64) Component (c) is at least one solvent selected from the group consisting of fatty alcohols having 6 to 11 carbon atoms. The fatty alcohols may be linear or branched. They are preferably branched fatty alcohols. It is additionally preferred that the fatty alcohols are saturated alcohols, particularly preferably saturated primary alcohols selected from the group consisting of C.sub.6H.sub.13OH, C.sub.7H.sub.15OH, C.sub.8H.sub.17OH, C.sub.9H.sub.19OH, C.sub.10H.sub.21OH, C.sub.11H.sub.23OH, for example 2-ethylhexanol or isononanol.

(65) It is preferred here that:

(66) component (a) is present at a proportion by mass of 20% to 80%, preferably of 30% to 70%, particularly preferably of 40% to 60%; and

(67) component (b) is present at a proportion by mass of 1% to 25%, preferably of 2% to 20%, particularly preferably of 4% to 15%;

(68) based on the total mass of the composition according to the invention.

(69) In the composition, components (a) and (b) are preferably present in a ratio by weight of (a) to (b) of from 2:1 to 15:1, preferably of from 3:1 to 13:1, particularly preferably of from 4:1 to 11:1.

(70) This composition comprising the inventive organomodified polysiloxane of formula (I) is added to the fuel as additive package.

(71) The following commercially available products may by way of example be present in the additive package: Surfynol® 420, Surfynol® 440, Surfynol® 2502, TEGO® Antifoam MR 465, TEGO® Antifoam MR 487, TEGO® Antifoam MR 507, TEGO® Antifoam KS 911, TEGO® Surten W 111, TEGO® Surten W 133, TEGO® SOS 25, TEGOPREN® 5801, TEGOPREN® 5803, TEGOPREN®5831, TEGOPREN® 5851, TOM AMINE® PA 14, TOMAMINE® PA 17, TOMAMINE® EC 2, TOMADOL® 25-3, ADOGEN® 570, ADOGEN® 141 D, ADOGEN® 172, VARINE® O, VARONIC® K 202 LC.

(72) Specifically, such additive packages may for example contain: cetane number improvers, e.g. 2-ethylhexyl nitrate; detergents, e.g. ADOGEN® 570, polyisobutene derivatives; corrosion inhibitors, e.g. ADOGEN® 141 D, VARINE® O; dehazers and stabilizers, e.g. TOMAMINE® EC 2, TOMADOL® 25-3; lubricity improvers, e.g. TOMAMINE® PA 17, fatty acids; defoamers, e.g. TEGO® Antifoam 507.

(73) In this connection, the amounts and combination are adapted to the respective requirements. The choice of the raw materials and the adjustment of the quantitative ratios are thus carried out depending on the required property profile.

(74) As an alternative, the inventive organomodified polysiloxane of formula (I) may be added directly to the fuel.

(75) The invention thus further relates to a fuel composition comprising diesel fuel, said diesel fuel preferably comprising biofuel, and at least one organomodified polysiloxane of formula (I) or an inventive composition comprising components (a), (b) and optionally (c).

(76) Diesel fuels are in this case preferably those fuels that satisfy the requirements of DIN EN 590 (October 2017 edition).

(77) The fuel composition according to the invention may either be anhydrous (“dry diesel”) or else contain water. In particular, the fuel composition may be a “moist” fuel composition, that is to say a fuel composition having a content of at least 250 ppm by mass of water based on the fuel composition.

(78) The proportion of organomodified polysiloxanes of formula (I) in the fuel composition is preferably chosen depending on the foaming behaviour of the diesel. The proportion of organomodified polysiloxanes of formula (I) in the fuel composition may therefore vary. It is preferred that the proportion by mass of the at least one organomodified polysiloxane, based on the total mass of the fuel composition, is from 1 ppm to 40 ppm, preferably from 2 ppm to 25 ppm, particularly preferably from 4 ppm to 15 ppm.

(79) In order to achieve a smaller release of SiO.sub.2 when the fuel composition is combusted, the proportion of silicon should be set to be as low as possible. It is thus preferred that the proportion by mass of silicon, based on the total mass of the fuel composition, is from 0.2 ppm to 2 ppm, preferably from 0.4 ppm to 1.5 ppm, particularly preferably from 0.5 ppm to 0.8 ppm.

(80) The proportion of biofuel in the fuel composition according to the invention may in principle be any desired proportion. However, it is preferred that the proportion by mass of biofuel, based on the total mass of the fuel composition, is at least 4%, preferably from 4% to 20%, particularly preferably from 4% to 8%. One or more biofuels can be present in the fuel composition according to the invention, if a plurality of biofuels are present in the fuel composition according to the invention, the statements made above regarding the proportion of biofuel relate to the sum total of all biofuels.

(81) The biofuel is preferably selected from the group consisting of fatty acid methyl esters, hydrogenated vegetable oils, hydrocarbons from biomass-to-liquid processes and hydrocarbons from gas-to-liquids processes.

(82) The biofuel is more preferably selected from the group consisting of fatty acid methyl esters, hydrogenated vegetable oils and hydrocarbons from biomass-to-liquid processes.

(83) Particularly preferably, the fuel composition comprises a biofuel based on fatty acid methyl esters (FAME), in particular on rapeseed oil methyl ester as FAME.

(84) The organomodified polysiloxanes of formula (I) are particularly well suited for the defoaming of diesel fuels which comprise biofuels.

(85) The invention thus further relates to the use of an organomodified polysiloxane of formula (I) or an inventive composition comprising components (a), (b) and optionally (c) for the defoaming of liquid fuels, preferably of diesel fuels, particularly preferably of diesel fuels which comprise biofuels.

(86) The present invention is illustrated by way of example in the examples listed below, without any intention that the invention, the scope of application of which is apparent from the entirety of the description and from the embodiments, be restricted to the embodiments mentioned in the examples.

EXAMPLES

Defoamer 1 (Inventive Example)

(87) Defoamer 1 was prepared as follows:

(88) A 500-ml four-neck flask with attached precision glass stirrer, reflux condenser and internal thermometer was initially charged with 117.3 g of a polydimethyl(methylhydrogen)siloxane copolymer, having an average chain length of 155 and having a hydrogen content of 1.12 eq SiH/kg, and 93.7 g of a hydroxy-functional allyl polyoxyalkylene, having an average molecular weight of 832 g/mol (determined according to iodine number), a propylene oxide proportion of 74 wt. % and an ethylene oxide proportion of 26 wt. % (wt. % based on the total mass of propylene oxide and ethylene oxide, EO/PO polyether prepared in accordance with the prior art by means of a KOH-catalysed reaction with allyl alcohol as starter alcohol), together with 7.6 g of 2-allylphenol, and the mixture was heated to 90° C. while stirring. The exothermic reaction was started by addition of 10 ppm of platinum in the form of the Karstedt catalyst (1.5 wt. % of Pt in decamethylcyclopentasiloxane) and after the exothermicity abated the mixture was stirred further at 90° C. The SiH conversion determined by gas volumetric means was 99.5% after 1.5 hours. Addition of 10.8 g of propylene glycol and filtration through a fluted filter afforded a clear, yellow-brownish liquid having a viscosity of 5540 mPa s at 25° C.

Defoamer 2 (Comparative Example)

(89) Defoamer 2 was prepared as follows:

(90) A 500-ml four-neck flask with attached precision glass stirrer, reflux condenser and internal thermometer was initially charged with 90.2 g of a polydimethyl(methylhydrogen)siloxane copolymer, having an average chain length of 155 and having a hydrogen content of 1.12 eq SiH/kg, and 108.16 g of a hydroxy-functional allyl polyoxyalkylene, having an average molecular weight of 832 g/mol (determined according to iodine number), a propylene oxide proportion of 74 wt. % and an ethylene oxide proportion of 26 wt. % (wt. % based on the total mass of propylene oxide and ethylene oxide, EO/PO polyether prepared in accordance with the prior art by means of a KOH-catalysed reaction with allyl alcohol as starter alcohol), and the mixture was heated to 90° C. while stirring. The exothermic reaction was started by addition of 10 ppm of platinum in the form of the Karstedt catalyst (1.5 wt. % of Pt in decamethylcyclopentasiloxane) and after the exothermicity abated the mixture was 35 stirred further at 90° C. The SiH conversion determined by gas volumetric means was 100% after one hour. Addition of 9.8 g of propylene glycol and filtration through a fluted filter afforded a clear, yellow-brownish liquid having a viscosity of 5588 mPa s at 25° C.

(91) Defoamer 2 differs from defoamer 1 in that it has no aromatic radical R.sup.3 and instead exclusively polyether radicals R.sup.2.

Defoamer 3 (Comparative Example)

(92) Defoamer 3 corresponds to defoamer E1 from DE 10 2007 031 287 A1 and was prepared, in accordance with the preparation instructions disclosed there, as follows:

(93) A 500-ml four-neck flask with attached precision glass stirrer, reflux condenser and internal thermometer was initially charged with 58.6 g of a terminally and pendently SiH-functional polydimethysiloxane, having an average chain length of 155 and having a hydrogen content of 2.40 eq SiH/kg, and 127.2 g of a hydroxy-functional allyl polyoxyalkylene, having an average molecular weight of 1471 g/mol (determined according to iodine number), a propylene oxide proportion of 88 wt. % and an ethylene oxide proportion of 12 wt. % (wt. % based on the total mass of propylene oxide and ethylene oxide, EO/PO polyether prepared in accordance with the prior art by means of a KOH-catalysed reaction with allyl alcohol as starter alcohol), 4.1 g of a hydroxy-functional allyl polyoxyalkylene, having an average molecular weight of 903 g/mol (determined according to iodine number), a butylene oxide proportion of 36 wt. % and an ethylene oxide proportion of 64 wt. % (wt. % based on the total mass of butylene oxide and ethylene oxide, EO/BO polyether prepared in accordance with the prior art by means of a KOH-catalysed reaction with allyl alcohol as starter alcohol), and also 12.2 g of 2-allylphenol, and the mixture was heated to 90° C. while stirring. The exothermic reaction was started by addition of 10 ppm of platinum in the form of the Karstedt catalyst (1.5 wt. % of Pt in decamethylcyclopentasiloxane) and after the exothermicity abated the mixture was stirred further at 90° C. The SIH conversion determined by gas volumetric means was 100% after one hour. Addition of 12 g of propylene glycol and 40.4 g of Solvesso® 150 (solvent based on aromatic hydrocarbons, commercially available from Brenntag) and filtration through a fluted filter afforded a clear, yellow liquid having a viscosity of 834 mPa s at 24° C.

Defoamer 4 (Comparative Example)

(94) Defoamer 4 is commercially available under the name TEGOPREN® 5851 (TP 5851) from Evonik industries AG. It is a polyether-modified polysiloxane that does not have any aromatic groups R.sup.3.

(95) Performance Test Methods:

(96) Defoaming Capacity:

(97) For the testing of the defoaming capacity of the defoamers, the latter are dissolved in an additive package according to the prior art. The additive package with defoamer is used in the diesel as specified at 320 ppm by mass (calculated as additive package without defoamer). This involves adding defoamer to the additive package in an amount such that the Si content reported in Table 2 is obtained.

(98) The composition of the additive package without defoamer can be found in Table 1:

(99) TABLE-US-00001 TABLE 1 Proportion by mass in the additive Function Raw material package Corrosion inhibitor C13 fatty alcohol 24- 21% propoxylate Lubricity improver PiB-phenol-formaldehyde- 21% amine Cetane number improver isoamyl nitrate 30% Demulsifier/dehazer alkoxylated acetylenediol  2% Solvent ethylhexyl alcohol 26%

(100) The foam disintegration of the diesel fuel admixed with additive package and defoamer is tested in a pressure apparatus (BNPé test: Liquid petroleum products—Determination of the foaming tendency of diesel fuels NFM 07-075:1997). This test is conducted as follows: 100 ccm of diesel fuel are filled into a glass tube and subjected to a pressure of 0.4 bar. The glass tube is connected via a solenoid valve at the base to a 250-ccm measuring cylinder. The diesel is injected into the measuring cylinder via the valve. After injection, the initial foam height [ml] and the time [s] until the foam has disintegrated are determined. At least double determinations are conducted. If the results of the disintegration time are more than 4 s apart and those of the foam height measurement are more than 10 ml apart, a further measurement has to be conducted. The foam height is given by the difference between the maximum foam height and the height of the liquid. The foam disintegration time indicates the duration of time required until the surface of the liquid is visible for the first time. The values reported in Table 2 are averages. The defoaming tests are conducted using B0 diesel and B10 diesel. B10 diesel is understood here to be a diesel fuel composed of 90 wt. % fossil diesel as per DIN EN 590 (October 2017 edition) and 10 wt. % rapeseed oil methyl ester (biofuel addition). B0 diesel is understood in turn to be a diesel fuel composed of 100 wt. % fossil diesel as per DIN EN 590 (October 2017 edition) without biofuel addition. The investigated diesel fuels B0 diesel and B10 diesel are also moist diesel fuels having a content of 250 ppm by mass of water.

(101) Surface Tension:

(102) The surface tension is determined as per standard ISO 19403-3:2017. Since the defoamers are not water soluble, a solvent/water mixture is chosen to this end that both dissolves the defoamer and also has a surface tension which corresponds to that of a diesel fuel admixed with biodiesel. The solvent/water mixture consists of 45 wt. % butyl glycol and 55 wt. % water and displays a surface tension of approximately 27.4 mN/m. For the determination of the surface tension, 1 g of the defoamer is dissolved in 1 l of the solvent/water mixture. The surface tensions thus determined are listed in Table 2, in order to achieve a defoaming effect, it is necessary for the surface tension of the solvent/water mixture with defoamer to be lower than that of the solvent/water mixture without defoamer.

(103) Pour Point

(104) The pour point of the pure defoamer is a measure of the cold stability and is determined as per DIN ISO 3016:2017-11.

(105) Performance Test Results:

(106) The results of the performance tests are summarized in Table 2.

(107) TABLE-US-00002 TABLE 2 Defoamer 1 2 3 4 Blank .sup.[1] Surface tension [mN/m] 22.6 23.8 26.5 26.3 27.4 Pour point [° C.] <−25 −5 <−25 −18 −3 Si content in the OMS [wt. %] .sup.[2] 15 15 9 12 — OMS content of the fuel 4 4 12 12 0 composition [ppm by weight] .sup.[3] Si content of the fuel 0.6 0.6 1.0 1.4 0 composition [ppm by weight] .sup.[4] Foam height B0 [ml] 29 35 45 60 132 Foam disintegration time B0 [s] 1 1 1 1 38 Foam height B10 [ml] 59 62 60 103 135 Foam disintegration time B10 [s] 1 1 1 9 42 .sup.[1] Blank refers to a corresponding composition without defoamer .sup.[2] Silicon content of the organomodified polysiloxane in wt. % (mass %, proportion by mass of silicon in the organomodified siloxane) .sup.[3] Concentration of the organomodified polysiloxane in the fuel composition consisting of B10/B0 diesel and additive package with/without defoamer in ppm by weight (ppm by mass, proportion by mass of the organomodified polysiloxane based on the total composition) .sup.[4] Silicon content of the fuel composition consisting of B10/B0 diesel and additive package with/without defoamer in ppm by weight (ppm by mass, proportion by mass of silicon based on the total composition)

(108) The inventive defoamer 1, already at a very low use concentration, leads to a sufficiently low surface tension, short foam disintegration times, low foam heights and a low pour point, and is better than non-inventive defoamers 2 to 4 in terms of at least one of these properties.

(109) Moreover, on account of the improved efficacy of defoamer 1, smaller use amounts are needed. This leads to a smaller release of SiO.sub.2 during combustion. Long-term diesel filters must therefore take up considerably less material. Loading by SiO.sub.2 particles is reduced.

(110) It is especially apparent that, for a foam disintegration time of fewer than 5 seconds and a reduction in foam height to less than 50% of the blank, defoamers are required in an amount of 0.6 ppm by weight of Si, based on fuel composition, instead of the hitherto customary amounts of 0.75 to 1 ppm by weight as are mentioned in the prior art. This signifies a 25 to 70% reduction in the SiO.sub.2 load for the diesel filter.