NO313243B1 - Use of organofunctionally modified polysiloxanes for foaming diesel fuels - Google Patents

Description

The hydrocarbon mixtures used as diesel fuel have the unpleasant property that when filling 1 storage containers such as storage tanks and fuel containers for motor vehicles, foam develops 1 compound with air. This leads to a delay in the filling process and to insufficient filling of the container. It is therefore common to add a certain amount of foaming agent to the diesel fuel. This anti-foaming agent must be effective at the lowest possible concentration and must not form harmful residues or negatively affect the combustion of the fuel when the fuel is burned in the engine. Correspondingly effective antl foam agents are described in the patent literature.

Accordingly, GB-PS 2 173 510 relates to a method for defoaming diesel fuel or jet fuel, whereby the fuel is added to an antl foaming agent which essentially consists of an organopolysloxane with the general formula:

where

the ratio x:y lies in the range 1:1 to 9:1,

each group R is a monovalent hydrocarbon group and at least 80# of the groups R are methyl groups,

each group R' is a substituted group of general formula Q(OA)nOZ, wherein

Q is a divalent group bonded to an S1 atom,

A is an alkylene group and at least 80% of these groups are

ethylene groups,

Z is a hydrogen residue or a group OCR", wherein R" is one

divalent group,

n has a value from 5 to 25, and

the copolymer has an average molecular weight such that the OA groups constitute 25 to 65 wt-96 of the calculated molecular weight of the copolymer, whereby

the copolymer may be dissolved in an organic solvent.

The concentration of the antifoam agent used is 1 to 100, preferably 5 to 50 ppm, based on the diesel fuel.

DE-OS 40 32 006 describes a method for defoaming and/or degassing organic systems by adding an anti-foaming agent containing organopolysiloxane to organic systems which may be formed from diesel oil or crude oil or their cleavage products. As organopolysiloxane, a polymer is used which consists of siloxane units with the general formula:

whereby

R means a monovalent hydrocarbon residue with 1 to 18 carbon atoms per rest,

A is one residue with general formula

in which

R<*> means a residue with the formula -CR<3>H-,

R<3> - hydrogen or monovalent organic residue,

R<2> means a residue with the formula -CR<4>H-CH3 or -(O^)3-,

R<4> - hydrogen or monovalent organic residue,

v, w is in any case 0 or integer, whereby v+w

average is 0 to 16,

x, y is 0 or 1, whereby x+y is 1 or 2,

a = 1, 2 or 3,

b = 0, 1 or 2 and

c - 1 or 2, whereby the sum b+c is not greater than 3.

The siloxanyl-alkenedlyl-bis-w-hydroxy-polyoxy-alkylene used and their preparation are described in DD-PS 255 737.

US-PS 5,334,227 describes the use of organopolysiloxanes for defoaming diesel fuel. Compounds with the general formula are used as organopolysiloxanes

whereby M - 0Q 5Si(CH2)3. D - OSi(CH 3 ) 2 . D" - 0Si(CH3)R,

D<*«> - OSi(CH3)R', R means polyether and R» a phenol derivative, x+y+z - 35 to 350, x/(y+z) - 3 to 6 and y/z - 0, 25 to 9.

DE-PS 43 43 235 describes a method for defoaming diesel fuel, whereby organofunctionally modified polysiloxanes of general formula

where

the radicals R<1> are alkyl or aryl radicals,

the residues R<2> are selected from several of the following compound classes: butene hydrates, alkane hydrates, polyethers and alkyl residues.

The described anti-foaming agents and further anti-foaming agents known from the prior art for diesel fuel have various disadvantages. Consequently, e.g. the use of the polysiloxane-polyoxyalkylene copolymers mentioned in 1 GB-PS 2 173 510 due to the necessary, relatively high application concentration and the silsium content, which typically amounts to between 10 and 15 wt-*, to a high silicon content for these diesel fuels (2 to 4 ppm).

The organopolysloxanes mentioned in DE-OS 40 32 006, US-PS 5 334 227 and DE-PS 43 43 235 do indeed lead to a reduced silicon content for the diesel fuels (0.4 to 1 ppm), but cannot, however, be used in any additive package without an adaptation of the solvent composition. In the foaming agent for diesel fuel almost without exception, the In 1 diesel fuel additive package is incorporated, and not added directly to the diesel fuel, this is a major technical disadvantage of these organopolysloxanes. Additive packages are added to the crude diesel oil to improve its properties.

Additive packages are mixtures of different additives, such as e.g. agents for improving the combustion behavior, agents for reducing the formation of smoke, agents for reducing the formation of harmful exhaust gases, inhibitors for the deterioration of the corrosion in the engine and its parts, interface substances, lubricants and the like. Such additive packages are e.g. described 1 JP-OS 05 132 682, GB-OS 2 248 068 and in the journal Mineraloltechnik, 37(4), 20 pp. The additives of the additive package are thereby dissolved in an organic solvent to form a stock concentrate which is added to the raw diesel fuel. Antl foaming agents with polar groups often cannot be incorporated evenly into this addltlv package or separate on storage.

The present invention therefore deals with the technical problem of finding antl foaming agents with improved acceptability with the commonly used additive packages.

According to the invention, this combination of properties is found in a selected organofunctionally modified polysilloxane. The object of the present invention is therefore the use of organofunctionally modified polysiloxane with general formula I

whereby the remains

R<1> means alkyl residues with 1 to 4 carbon atoms or aryl residues, where, however, at least 80* of the residues R1, are

methyl residues,

R<2> are the same or different 1 molecule, of which

30 to 90* has the meaning of the remainder R<1> and

70 to 10* consists of a mixture of residues R<2A> and R2**, whereby the residues R<2A> are more polar than the residues R2B, and whereby the residues R2A are selected from the following residues:

(a) a phenol derivatate of general formula:

where

R<3> is a divalent residue which is composed of one or more of the following groups:

hydrocarbon residues which are optionally substituted, aromatic residues which are optionally substituted, polyoxyalkylene residues and R<4> is a monovalent residue which is the same or different selected from the group: hydrogen residue, alkyl residue, alkyloxy acid residue, hydroxy residue and

z is a number from 0 to 4, or

(b) means the remainder

whereby

R<5> is a hydrogen or alkyl residue,

c is a number from 1 to 20,

d is a number from 0 to 50,

e is a number from 0 to 50 or

(c) the residue -(CH2-)fOR<6>,

whereby

r<6> is a hydrogen or a monovalent organic residue, f is a number from 3 to 20 or

(d) means the residue -(CH2-)g(OC2H4-)n(OC3H6-J^OR7

whereby

R<7> means a hydrogen or a monovalent organic residue, g is a number from 3 to 6,

h is a number from 1 to 50,

i is a number from 0 to 20 and

the ratio h:i > 5:2, and

the residues R<2>^ are selected from the following residues:

(e) the remainder

whereby

R<8> is a hydrogen or alkyl residue,

R^ is an alkyl, acyl or trialkylsilyl residue,

k is a number from 1 to 20,

m is a number from 0 to 50,

n is a number from 0 to 50 or

(f) the residue -(CH2-)0CH3,

whereby

0 is a number from 5 to 30, or

(g) the residue -(CH2-)g(OC2H4-)h(OC3H6-) i0K7

whereby

R<7> is a hydrogen or a monovalent organic residue,

g is a number from 3 to 6,

h is a number from 0 to 35,

1 is a number from 1 to 50 and

the ratio h:i < 5:2, and

whereby at least 10$ of the residues R<2A> are equal to the residue (a) and at least 10$ of the residues R<2>^ or R<2B> are selected from the residues (b), (c), (e) or (f ),

a is a number from 1 to 400,

b is a number from 0 to 10,

for skimming diesel fuel in quantities of 0.5 to 50 ppm, based on the diesel fuel.

The siloxane lattice can be straight chain (b = 0) or also branched (> 0 to 10). The value of b, in the same way as the value of a, is to be understood as average values in the polymer molecule, as the polysiloxanes used according to the invention - as a rule - are in the form of equilibrated mixtures.

The radicals Ri are alkyl radicals with 1 to 4 carbon atoms, such as methyl, ethyl, propyl or butyl radicals, or aryl radicals, whereby the phenyl radicals are preferred. The manufacturing and price conditions are methyl residues preferred, so that at least 80% of the residues R<1> must be methyl residues. Particular preference is given to such polysloxanes whereby all the residues R<1> are methyl residues.

The essence of the present invention consists in particular in the use of organofunctionally modified polysloxanes which exhibit organofunctional residues R<2>. These residues R<2> are selected from two main groups, namely from the residues R<2A> and R<2B>. These two residues R<2A> and R<2B> differ in polar character: The residues R<2A> are more polar than the simultaneously present residues R<2B>. With this choice of the residues R<2A> and R2B, it is possible to optimize the compatibility of the polysloxanes of formula I which are used according to the invention with the diesel fuel and at the same time to achieve optimal defoaming effect through optimal compatibility.

The ratio between the polar residues R<2A> to the less polar residues R<2B> can vary within wide limits. It has proven appropriate to set a ratio of 10:1 to 1:3. Particularly preferred is a ratio of 6:1 to 2:1.

However, not all residues R<2> must be selected from residues R<2A> and R<2B>. A part of these residues can also have the meaning of the residues R<1>, i.e. a part of the residues R<2> can also have the meaning of alkyl residues with 1 to 4 carbon atoms or of aryl residues. Also in this case should preferably be methyl residues.

R<2> can therefore be the same or different in the molecule and is to be defined as follows: 30 to 90* of all residues R<2> can have the meaning of the residues

R<1>, however, must

70 to 10* of the residues R<2> consist of a mixture of the residues R2A and R2B.

In the following, the possible polar residues R<2A> will first be described in more detail. Here are the following leftovers to choose from:

The residue (a): -R<3->(C6H4_ZR<4>Z)-0H

In residue (a), whereby it is a phenol derivative, the residue R<3> is a divalent residue which is composed of one or more of the following groups: hydrocarbon residues, which are optionally substituted, aromatic residues which are optionally substituted and polyoxyalkylene residues. An alkylene residue with 2 to 6 carbon atoms is preferred. The residue R<*> is a monovalent residue, R<4> can be the same or different and is selected from the groups: hydrogen residue, alkyl residue, alkyloxy acid residue, hydroxy residue. Preferred are hydrogen residues, methyl residues and methoxy acid residues. The index z is a number from 0 to 4.

These residues (a) can be introduced into the molecule of the polysiloxane by addition of allyl or vinyl derivatives to SiH groups of the polysiloxane in the presence of a hydrosilylation catalyst, e.g. corresponding to the method 1 US-PS 5 334 227. Examples of . corresponding allyl derivatives are allylphenol and Eugenol (4-allyl-2-methoxyphenol).

The remainder (b):

In residue (b), R*> is a hydrogen or alkyl residue, especially a lower alkyl residue with 1 to 4 carbon atoms. Hydrogen residue is preferred. The index c is a number from 1 to 20, preferably 1. The indices d and e are independently numbers from 0 to 50. Preferred is a residue (b), whereby R<5> is a hydrogen residue, the index c is equal to 1 and The indices d and e are independent of each other in any case 0 to 10. These indices are average numbers, as it is known that when alkylene oxides, such as ethylene oxide and propylene oxide, are added to alcohols, a mixture of compounds of different chain lengths is obtained .

These residues (b) can be introduced 1 molecule of the polysiloxane by addition of alkenedlyl-bls-w-hydroxy-polyoxyalkylenes to SiH groups of the polysiloxane 1 in the presence of a hydro-silylation catalyst corresponding to method 1 DD-PS 255 737.

The residue (c): -(CH2)f-OR<6>

In residue (c), R<6> is a hydrogen or a monovalent organic residue. As monovalent organic residues, the usual end-blocking groups, especially lower alkyl residues with 1 to 4 C atoms, come into question. The index f is a number from 3 to 20, whereby a numerical value of 6 is preferred.

These residues (c) can be introduced by means of a hydrosilylation reaction as already described above by addition of alkenols or their derivatives to SiH groups of organopolysiloxanes. Examples of such an alkenol and its end-blocked derivative are hexenol or the alkyl ether of hexenol.

The residue ( d): -(CH2)g(OC2H4-)h(OC3H6-) 10K7

In residue (d), R<7> is a hydrogen or a monovalent organic residue. Preferably, R<7> is a hydrogen or methyl residue. The index g is a number from 3 to 6, the index h is a number from 1 to 50 and the index i a number from 0 to 20, whereby the number ratio h:i > 5:2. Preferably, the index g has a value of 3, the index h has a value of 8 to 30 and the index 1 a value of 0 to 12.

The residues (d) can also be introduced by a hydrosilylation reaction already described above by addition of alkenol polyethers or their derivatives to SiH groups of organopolysiloxanes.

There now follows a description of the residues R<2B>, whose polarity is lower than that of the residues R<2A>. Here are the following leftovers for selection:

The rest (e):

The residue (e) can be compared with the residue (b) (Within the possibility of the residue R<2A>) Gg differs from this by the blocking of the terminal hydroxyl groups. The end-blocking group R 1 is an alkyl, acyl or trialkylsilyl group. The methyl, acetyl or trlmethylslyl residue is preferred. With this modification, the acceptability of the number foaming agent in the addltlv package is significantly improved. With respect to the definition, the residues R<5> and the residue R<8> correspond to each other, the indices c, d and e correspond to the Indices k, m and n. The same applies to the preferred meanings.

The residue (f): -(CH2-)0CH3

In the residue (f), the Index o has a numerical value of 5 to 30, preferably 11 to 17. It is therefore a question here of long-chain alkyl residues. These residues significantly improve the compatibility of the sloxane used according to the invention in the additive package, but also in the diesel fuel.

These residues can be obtained by hydrolyzing addition of α-olefins to SiH groups of the organopolysiloxane.

The residue ( g): -(CH2-)g(OC2H4-)n(OC3H6-JjOR7

The residue (g) can be compared with the residue (d) (Within the possibilities of the residue R2A) and differs from it by the number of the different oxyalkylene units: The index h is a number from 0 to 35, the index i a number from 1 to 50, whereby the ratio between the Indices h:l < 5:2. Preferably h has a numerical value from 0 to 17 and 1 a numerical value from 6 to 26. g is a number from 3 to 6, preferably 3.

The residues (g) can also be introduced by means of a hydrosilylation reaction as already described above by addition of alkenol polyethers or their derivatives to SiH groups of the organopolysiloxane.

The organofunctionally modified polysloxanes used according to the invention can be added directly to the diesel fuel, whereby an addition of 0.5 to 50 ppm, relative to diesel fuel fat, is sufficient for effective defoaming. Preferably, the addition rate is 2 to 20 ppm. Due to this low additive amount, a low absolute Si content results in the diesel fuel.

However, it is also possible and in practice the preferred method to add the polysiloxane used according to the invention to the so-called addltlv package, which is described in the introduction.

In the following examples, the preparation of the organofunctionally modified organopolysloxanes of formula I which are used according to the invention is first shown. The products produced in these examples are denoted by El to E7.

Examples 1 to 7

Preparation of the anti-foaming agent El - E6

The reactants (see table) are placed in a 1000 ml reaction flask, equipped with a stirrer, dropping funnel, thermometer and reflux condenser, together with 100 g of toluene.

With stirring, the catalyst (20 ppm hexachloroplatinic acid ^PtClf,, in some toluene) is added and then heated to 120°C. At this temperature, the SiH-functionalized polydimethylsiloxane (see table) 1 is added dropwise during approx. 30 minutes in such a way that, despite the exothermic reaction occurring, a temperature of 130* C is not exceeded. After the addition is complete, it is again stirred at a maximum of 130 "C. The turnover control takes place every hour using the S1E value. The average reaction duration amounts to approx. 4 hours, whereby the turnover must amount to at least 99* of the theoretical value.

During subsequent distillation 1 oil pump vacuum at 130°C, the solvent and volatile by-products are removed. After cooling, a filtration takes place, whereby the catalyst residues are separated.

Production «■▼ antl-foam memldlet E7

37.4 g (0.2 mol) of ethoxylated 2-butyne-1,4-diol are placed in a 1000 ml reaction flask, equipped with a stirrer, dropping funnel, thermometer and reflux condenser. While stirring, 20.4 g (0.2 mol) of acetic anhydride are added dropwise. The acetylation reaction is exothermic. The reaction mixture is heated after the dropwise addition to 120<*>C. When the temperature is reached, the remaining acetic acid is distilled off in an oil pump vacuum. Then 273.0 g (0.195 mol) of 4-allylphenol, 58.3 g (0.26 mol) of hexadecene and 23.1 mg (20 ppm) of hexachloroplatinic acid H2PtClD, 1 some toluene are suspended and heated again to 120<*>C. At this temperature, 217.0 g (0.133 mol) of the SiH-functionalized polydlmethylsiloxane (u-21; v-7.5) 1 is added dropwise over the course of 30 minutes in such a way that, despite an exothermic reaction beginning, a temperature is not exceeded at 130°C. After the addition is finished, stir again at a maximum of 130°C. The turnover control takes place every hour using the SiH value. The average reaction duration is approx. 4 hours, whereby the turnover must amount to at least 99* of the theoretical value.

During subsequent distillation in an oil pump vacuum at 130°C, the solvent and volatile by-products are removed. After cooling, a filtration takes place whereby the catalyst residues are separated.

Structure of antifoam E1 to E7

The application technical comparison trials are carried out with products according to the state of the art and the connections El to E7. As a comparison88, the number foaming agent A (corresponding to GB-PS 2 173 510) and the number foaming agent B (corresponding to US-PS 5 334 227) serve as:

Anti-foam part A:

RY - - (CH2-)3(OC2H4-)140H

Amount of foaming agent B: (CH3)3SiO((CH3)2SiO)80(R<Y>(CH3)SiO)10(R<Z>(CH3)SiO)5Si(CH3)3

RY - -(CH2-)3(OC2H4-)80H

To investigate the defoaming ability of the siloxanes used according to the invention, this is dissolved in an additive package according to the state of the art and a certain amount of this mixture is stirred into 500 g of additive-free diesel fuel. The mixing ratio between siloxane and the addltlv package and the amount of this additive added to the fuel is chosen in such a way that the desired siloxane concentration is achieved and at the same time a concentration of the addltlv package and the amount of this additive added to the fuel is chosen in such a way that one achieves the desired siloxane concentration and at the same time a concentration of the additive package of 500 ppm in the diesel fuel. The concentration of the compound According to the invention 1 diesel fuel is varied between 2 and 20 ppm. An approximate critical concentration is determined for each product, below which a clear reduction in monitoring occurs for the first time.

The foam decomposition of the diesel fuel mixed with additives and defoamers is tested in a pressure apparatus. This apparatus essentially consists of a 1-litre pressure container that can be pressurized with a constant compressed air pressure and a 250 ml measuring cylinder. An outlet nozzle of the pressure vessel equipped with a magnet vent 11 is thereby located centered above the must le awl The inside and dips In 1 this a few centimeters. For each test, 100 ml of the diesel fuel to be tested is filled into the pressure vessel, a compressed air pressure of 0.4 bar is applied and, with the help of the solenoid valve, this is released over a period of 3.9 seconds into the measuring cylinder. The difference in volume that appears from the maximum foam level and the level for a foam-free liquid 1 measuring cylinder The inside is indicated as 1 ml and is designated as foam volume. The time that elapses between the achievement of the maximum foam level and the lifting of the foam layer above the liquid into a foam ring is measured in seconds and is referred to as the foam decomposition time. For each amount of foaming agent, three measurements are carried out and the average value of foam height and decomposition time is determined.

To investigate the compatibility with the antl foaming agent, three different additive packages corresponding to the state of the art are used. In any case, 1 g of the sloxane used according to the invention is added to 19 g of an additive package and stirred. The Antl foam medium is said to be compatible with the addltlv package when, during one week at -10°C, no cracking or formation of a second phase 1 addltlv package can be determined. The result of the compatibility test is judged to be positive and indicated with a "+" when the tested foaming agent is compatible with all three tested additive packages, otherwise it is indicated as negative and indicated with The following table compares the measurement results for the foam decomposition test and the compatibility test. The indicated application concentrations are, as described above, the critical application concentration for any foam component, the undershooting of which leads to a significant deterioration of the defoaming behavior. The silicon content of the diesel fuel mixed with the anti-foaming agent is calculated from the application concentration of the anti-foaming agent and its theoretical silicon content, which is determined using the average structure formula:

The compilation shows that the organofunctionally modified polysloxanes El to E7 used according to the invention are very well suited for defoaming diesel fuel. In contrast to the combination products, they show excellent compatibility with the fuel additive packages. The use of additional solvents can thus be avoided and the danger that the foaming agent, e.g. under adverse weather conditions, during storage, separation from the addltlv package must be avoided.

Claims (1)

1. Use of organofunctionally modified polysloxanes of general formula (I) where the remains R<1> is alkyl residues with 1 to 4 carbon atoms or aryl residues, whereby however at least 80* of the residues R<1> are methyl residues, R<2> 1 molecule are the same or different, of which 30 to 90* have the meaning of the residue R<1> and 70 to 10* consist of a mixture of residues R <2A> and R<2B>, whereby the residues R<2A> are more polar than the residues R<2B>. and wherein the residues R<2A> are selected from the following residues: (a) a phenol derivative of the general formula: whereby R<3> is a divalent residue which is composed of an or several from the following groups: hydrocarbon residues, which are optionally substituted, aromatic residues, which are optionally substituted, polyoxyalkylene residues and R<4> is a monovalent residue, these can be equal or different and is selected from the groups: hydrogen residue, alkyl residue, alkyloxy acid residue, hydroxy residue and z is a number from 0 to 4, or (b) the remainder whereby R5* is a hydrogen or alkyl residue, c is a number from 1 to 20, d is a number from 0 to 50, e is a number from 0 to 50 or (c) the residue -(CH2-)fOR<6>, where R** is a hydrogen or a monovalent organic residue, f is a number from 3 to 20 or (d) the residue means -(CH2-)g(0C2H4-)n(0C3H6-J^OR<7 >whereby R<7> is a hydrogen or a monovalent organic residue, g is a number from 3 to 6, h is a number from 1 to 50, i is a number from 0 to 20 and the ratio h:l > 5:2, and the residues R^<B> are selected from the following residues: (e) the residue whereby R<8> is a hydrogen or alkyl residue, R^ is an alkyl, acyl or trialkylsilyl residue, k is a number from 1 to 20, m is a number from 0 to 50, n is a number from 0 to 50 or (f) the residue -(CH2-)0CH3, wherein.0 is a number from 5 to 30, or (g) the residue -(CH2-)g(OC2E4-)h(0<C>3<H>6-)i0R7 wherein R<7> is a hydrogen or a monovalent organic residue, g is a number from 3 to 6, h is a number from 0 to 35, 1 is a number from 1 to 50 and the ratio h:i < 5:2, and whereby at least 10% of the residues R<2A> are equal to the residue (a) and at least - 10% of the residues R<2A> or R2B are selected from the residues (b), (c), (e) or (f), a is a number from 1 to 400, b is a number from 0 to 10, for skimming of diesel fuel in amounts of 0.5 to 50 ppm, specified on the basis of the diesel fuel.