Siloxane-functionalized silica

Abstract

The present invention relates to silica functionalized with siloxanes of the following formula (I): [SiO 4 / 2 ] a [R 1 SiO 3 / 2 ] b [R 3 R 1 SiO 2 / 2 ] c [R 1 3SiO 1 / 2 ] d [O 1 / 2 R 2 ] e (I). The indices a, b, c, d, e each independently have integer values: a is from 0 to 100, b is from 0 to 100, c is from 0 to 50, d is from 3 to 200, and e is from 0 to 5, provided that the sum of a, b and c is at least 1 and that for more than 50% of the siloxane in the mixture, the sum of a, b and c is ≥ 4; and wherein R 1 are each independently H, an amino group, an unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 Aryl; wherein R 2 are each independently H, unsubstituted or substituted C1-C 20 Hydrocarbon group; wherein R 3 Each is independently H, an amino group, an unsubstituted or substituted C2-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 Aryl, wherein "substituted" means that there is, independently of each other, at least one substituent selected from the group consisting of: OR Y , ‑NR Y 2. ‑SH, ‑SR Y , epoxy, ‑COOR Y ,‑CHO,‑CN,‑NCO,‑OCOOR Y , ‑NR Y ‑COOR Y , ‑NR Y ‑CO‑NR Y ,‑SiR Y 3and‑OSiR Y 3, where R Y are each independently H, an amino group, an unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14Aryl.

Description

[0001] The present invention relates to a method for preparing a product containing [Me2SiO 2 / 2 ] units of the general formula (I) siloxane-functionalized silica and a method for preparing such silica.

[0002] Siloxanes are an industrially important class of compounds used in many technical fields. Their preparation is a key process in industrial organosilicon chemistry. For example, one established process on an industrial scale involves hydrolytic condensation starting with chlorosilanes according to the following reaction equation:

[0003] 2R3Si-Cl+H2O=>R3Si-O-SiR3+2HCl

[0004] Another well-established process is the hydrolytic condensation of alkoxy-containing silanes and siloxanes, which are raw materials produced on an industrial scale:

[0005] R3Si-OR+H2O=>R3Si-OH+ROH;

[0006] 2R3Si-OH=>R3Si-O-SiR3+H2O

[0007] Fumed silica is a widely used additive for controlling the flow properties of, for example, adhesives, sealants and coatings such as paints or varnishes. They are used in particular to adjust viscosity, shear-thinning and thixotropic properties, and yield point.

[0008] Non-functionalized silicas are typically used in non-polar, higher molecular weight systems with high solvent content.

[0009] For polar, low-molecular-weight systems with a low solvent content or solvent-free systems, hydrophobic silicas are generally used. For example, hydrophobization can be carried out by functionalization with polyorganosiloxanes (e.g. polydimethylsiloxane, PDMS) or chloroalkylsilanes (especially chloromethylsilane), the silica functionalized in this way having monomethylsiloxy, dimethylsiloxy or trimethylsiloxy groups.

[0010] The nomenclature for polyorganosiloxanes (siloxanes for short) is based on the functionality of their units. There are four different units (building blocks): monofunctional, difunctional, trifunctional, and tetrafunctional (M, D, T, Q). M-siloxanes serve as chain ends. D-siloxanes are commonly used to build linear and cyclic siloxanes. T-siloxanes and Q-siloxanes are used to crosslink chains and build branched and hyperbranched networks.

[0011] When bifunctional synthetic units are used to prepare siloxanes, cyclic siloxanes can be formed. If silicas are subsequently functionalized with these siloxanes, they also contain cyclic siloxanes.

[0012] Contains [Me2SiO 2 / 2 ] units, particularly to form cyclic D-siloxanes such as hexamethylcyclotrisiloxane (D3, [Me2SiO 2 / 2 ]3), octamethylcyclotetrasiloxane (D4, [Me2SiO 2 / 2 ]4), decamethylcyclopentasiloxane (D5 or [Me2SiO 2 / 2 ]5) and dodecamethylcyclohexasiloxane (D6 or [Me2SiO 2 / 2 ]6) and higher homologues. In the EU, D4, D5 and D6 meet the requirements of Regulation (EC) No 1907 / 2006 (REACH Regulation) and are classified as vPvB (very persistent, very bioaccumulative), PBT (persistent, bioaccumulative, toxic), and ultimately SVHC (substances of very high concern). REACH Regulation initially required that the content of these D-rings (D-cycle) be reduced to below 1000ppm. In the 15th amendment to the regulation, the limit was reduced to 250ppm. As a result, a method for producing D-siloxanes with a low D-ring content has been established by removing these rings by distillation or by targeted chemical conversion.

[0013] WO 96 / 18670 A1 describes a process for preparing essentially acyclic polyorganosiloxane mixtures, in which ring formation is suppressed by adding equilibration catalysts.The polyorganosiloxane mixtures can also be functionalized.

[0014] EP 1 580 215 B1 describes a process for producing amino-functional organosiloxanes having a low D4 content.

[0015] The use of T and Q units in combination with D-siloxanes is also known. For example, US Pat. No. 4,193,885 describes the use of branched methylpolysiloxanes as heat transfer media, wherein the content of T and Q units is preferably less than 10 mol %.

[0016] If D units (Me2SiO 2 / 2 ), the formation of the D-loop can be completely excluded.

[0017] The preparation of D-free siloxanes has hitherto been limited to low-molecular-weight TM systems (systems consisting exclusively of T and M units) or QM systems and primarily concerns their use as heat-transfer fluids and in cosmetics.

[0018] WO 2010 / 103103 A1 describes the use of polyorganosiloxanes as power and / or heat transfer fluids, also allowing T and Q units and thus pure TM and QM systems. One of the silicon-bonded groups has at least two carbon atoms.

[0019] RU 2 221 826 C1 relates inter alia to the use of TM3[(Me)Si(OSiMe3)3] in a mixture with linear DM siloxanes as a component of a heat transfer fluid.

[0020] WO 2016 / 124439 A1 describes the use of QM4[Si(OSiMe3)4] as a heat transfer fluid.

[0021] WO 2017 / 058713 A1 describes the use of TM3 and QM4 as components of compositions for skin care applications.

[0022] Methods for producing QM and TM systems are also known.

[0023] EP 1 205 505 A2 and EP 0 495 676 A1 describe methods for preparing alkoxy-rich TM oligomers and polymers, respectively, which may contain Q units and unsaturated functional groups. WO 2018 / 141383 A1 describes a continuous process for producing QM4, Q(VM2)4[Si(OSi(Me)2(C(H)═CH2))4], and TM3.

[0024] Other approaches can produce low molecular weight QM or TM systems with unsaturated or amino functional groups.

[0025] JP 11021289 A2 describes a process for preparing 3-aminopropyl-substituted TM3 and QM4, while EP 3 153518 A1 relates to a process for preparing monovinylated TM3 and QM4.

[0026] WO 2018 / 184668 A1 describes an alternative method for producing (also linear) TM siloxanes by silylation of alkali metal silanolates. However, in this case, stoichiometric amounts of alkali metal salts are produced.

[0027] The functionalization of silica with M-, D- and / or T-groups is known. This is usually done as a combination of silanol groups of silica and M, D and / or T units (R n SiX, wherein X is a reactive leaving group, n = 1, 2 or 3) condensation reaction between.

[0028] For example, EP 0 686 676 A1 describes the silylation of silica with M-, D- and / or T-siloxanes. The siloxanes are added to the silica in the form of a finely divided aerosol.

[0029] EP 0 926 210 A1 and DE 10 2006 017 592 A1 each describe a process for the hydrophobization of silica using organomonosilanes, wherein the silica is functionalized with M, D and / or T groups.

[0030] A disadvantage of the above-mentioned silica functionalization methods is that these silicas may contain D-rings.

[0031] It is an object of the present invention to provide hydrophobic silicas which are essentially free of D-rings.

[0032] Essentially, it should be understood that in this case at least the detection limit of 60 ppm for the D-ring of the analytical method used here is not reached.

[0033] This object is achieved by silica functionalized with siloxanes of the general formula (I),

[0034] [SiO 4 / 2 ] a [R 1 SiO 3 / 2 ] b [R 3 R 1 SiO 2 / 2 ] c [R 1 3SiO 1 / 2 ] d [O 1 / 2 R 2 ] e (I) wherein the indices a, b, c, d, e each independently have an integer value:

[0035] a is 0 to 100,

[0036] b is 0 to 100,

[0037] c is 0 to 50,

[0038] d is 3 to 200,

[0039] e is from 0 to 50, provided that the sum of a, b and c is at least 1 and, for more than 50% of the siloxane in the mixture, the sum of a, b and c is ≥ 4;

[0040] where R 1 are each independently H, an amino group, an unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 aryl;

[0041] where R 2are each independently H, unsubstituted or substituted C1-C 20 hydrocarbon group;

[0042] where R 3 are each independently H, an amino group, an unsubstituted or substituted C2-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 Aryl, wherein substituted means that at least one substituent selected from the following group is present independently of each other: OR Y 、-NR Y 2. -SH, -SR Y , epoxy, -COOR Y 、-CHO、-CN、-NCO、-OCOOR Y 、-NR Y -COOR Y 、-NR Y -CO-NR Y 、-SiR Y 3and-OSiR Y 3, where R Y are each independently H, an amino group, an unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 Aryl.

[0043] Preferably, the indices a, b, c, d, e each independently have the following integer values:

[0044] a is 0 to 30,

[0045] b is 0 to 30,

[0046] c is 0 to 15,

[0047] d is 3 to 60, and

[0048] e is 0 to 15.

[0049] The siloxane preferably has no Q units, and the index a has a value of 0. In other words, the functionalized silica preferably does not have any Q groups as functionalization.

[0050] The siloxane preferably has no D units, and the index c has a value of 0. In other words, the functionalized silica preferably does not have any D groups as functionalization.

[0051] The D-ring content is preferably less than 250 ppmw, particularly preferably less than 150 ppmw, and especially less than 60 ppmw. The D-ring content can be determined using a gas chromatograph equipped with a flame ionization detector (GC-FID). The detection limit here is generally 60 ppmw (see point 8 of the measurement method). Generally, the D-ring content should be close to zero or 0 ppmw, since the siloxanes used for functionalization generally do not contain D-rings, and the reaction conditions during functionalization are generally not favorable for D-ring formation.

[0052] The surface area of the functionalized silica is preferably 30-400 m 2 / g, particularly preferably 40-300m 2 / g, especially 50-200m 2 / g (measured by the BET method according to DIN 66131 and 66132).

[0053] The silanol group content of the functionalized silica (relative to the residual silanol content of the starting silica) is preferably from 15 to 45% (see point 9 of the measurement method).

[0054] The carbon content of the functionalized silica is preferably 1-10% (see point 10 of the measurement method).

[0055] The functionalized silicon dioxide preferably has a volatile component content at 300° C. of 0.5 to 10%, particularly preferably 2 to 8%, and in particular 3 to 7%.

[0056] The functionalized silicon dioxide preferably has a content of volatile components at 105° C. of 0.1 to 0.5%, particularly preferably 0.2 to 0.3% (see point 11 of the measurement method).

[0057] The thickening effect of the functionalized silicon dioxide is preferably 1-10 mPas, particularly preferably 2-9 mPas, in particular 3-8 mPas (see point 12 of the measurement method).

[0058] Another aspect of the present invention relates to a process for producing functionalized silica, in particular the above-mentioned silica, by reacting unfunctionalized silica with a siloxane of the general formula (I).

[0059] [SiO 4 / 2 ] a [R 1 SiO 3 / 2 ] b [R 3 R 1 SiO 2 / 2 ] c [R 1 3SiO 1 / 2 ] d[O 1 / 2 R 2 ] e (I)

[0060] where the indices a, b, c, d, and e each independently have integer values (the above conditions apply):

[0061] a is 0 to 100,

[0062] b is 0 to 100,

[0063] c is 0 to 50,

[0064] d is 3 to 200, and

[0065] e is 0 to 50, provided that the sum of a, b and c is at least 1 and, for more than 50% of the siloxanes in the mixture, the sum of a, b and c is ≥ 4, and the group R 1 , R 2 , R 3 As defined above, and wherein the alkoxy content (R 2 ≠H) is less than 5 mol%, silanol group content (R 2 =H) is less than 500 ppm, and the viscosity of the siloxane is 5-500000 mPa*s.

[0066] Preferably, the indices a, b, c, d, e each independently have the following integer values:

[0067] a is 0 to 30,

[0068] b is 0 to 30,

[0069] c is 0 to 15,

[0070] d is 1 to 60, and

[0071] e is 0 to 15, wherein the alkoxy content is less than 1% by weight, the silanol content is less than 350 ppm, and the viscosity of the siloxane is 60 to 10,000 mPa*s, in particular 50 to 500 mPa*s.

[0072] After storage for 4 weeks at 25° C., the viscosity (at 25° C.) of the silicones typically changes by less than 10%, in particular by less than 5%. Furthermore, silicones are generally hydrophobic and immiscible with water under standard conditions (25° C. and 1.013 bar).

[0073] The value of index a and / or index c is preferably 0. In particular, the siloxane does not have [R 3 R 1 SiO 2 / 2] units (c=0), and can be referred to as TM, QTM or QM siloxanes depending on their composition. Siloxanes containing TM, QTM and / or QM siloxanes (silicone mixtures) can be summarized as Q / T / M siloxanes.

[0074] In particular, the siloxanes used contain no D-rings.

[0075] Preferably, the ratio of the index d to the index b is from 0.15 to 3, preferably from 0.2 to 2, particularly preferably from 0.3 to 1.

[0076] Siloxane group R 1 、R 2 and R 3 C1-C can be defined independently 20 Examples of alkyl groups are:

[0077] Methyl, ethyl, n-propyl, isopropyl, 1-n-butyl, 2-n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl such as n-hexyl, heptyl such as n-heptyl, octyl such as n-octyl and isooctyl such as 2,2,4-trimethylpentyl, nonyl such as n-nonyl, decyl such as n-decyl, dodecyl such as n-dodecyl and octadecyl such as n-octadecyl; cycloalkyl such as cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl.

[0078] C6-C 14 Examples of the aryl group may include phenyl, naphthyl, anthracenyl, and phenanthrenyl.

[0079] Examples of the aryl group may include o-, m-, p-tolyl, xylyl, and ethylphenyl; and alkyl groups such as benzyl, α-, and β-phenylethyl.

[0080] C2-C 20 Examples of the alkenyl group may include vinyl, allyl, 5-hexen-1-yl, E-4-hexen-1-yl, Z-4-hexen-1-yl, 2-(3-cyclohexenyl)ethyl, and cyclododeca-4,8-dienyl.

[0081] Examples of amino groups may include:

[0082] Morpholinyl-(CH2)-,

[0083] H2N(CH2)2NH(CH2)CH(CH3)CH2-,

[0084] (cyclohexyl)NH(CH2)3-,

[0085] (cyclohexyl)NH(CH2)-,

[0086] CH3NH(CH2)3-,

[0087] (CH3)2N(CH2)3-,

[0088] CH3CH2NH(CH2)3-,

[0089] (CH3CH2)2N(CH2)3-,

[0090] CH3NH(CH2)2NH(CH2)3-,

[0091] (CH3)2N(CH2)NH(CH2)3-,

[0092] CH3CH2NH(CH2)2NH(CH2)3-,

[0093] (CH3CH2)2N(CH2)2NH(CH2)3.

[0094] Group R Y Preferably, each is independently selected from the group consisting of 3-aminopropyl, [N-(2-aminoethyl)-3-aminopropyl], methyl, ethyl, propyl, butyl, 2-butyl, tert-butyl, neopentyl, hexyl, vinyl, allyl, hexenyl, phenyl, benzyl, tolyl and naphthyl. In particular, R Y Selected from the group comprising methyl, ethyl, vinyl, allyl, hexenyl and phenyl.

[0095] C1-C 20 Alkyl, C2-C 20 Alkenyl and / or C6-C 14 Aryl groups are preferably unsubstituted.

[0096] Group R 2 Preferably each independently is unsubstituted C1-C 12 Hydrocarbyl, particularly preferably C1-C6 hydrocarbyl, especially methyl or ethyl.

[0097] Preferably, the siloxane used is a replacement for polydimethylsiloxane (Formula A) in which R 1 Preferably, each is independently selected from the group consisting of methyl, ethyl and phenyl. 2 Preferably, each independently selected from the group consisting of: H, methyl and ethyl, R 3 Preferably, each is independently ethyl or phenyl.

[0098]

[0099] According to another embodiment, the siloxane is a replacement for vinyl polysiloxane. In vinyl polysiloxane, the single methyl group per molecule is replaced by an unsaturated functional group (based on formula A). The group R 1Preferably each is independently selected from the group consisting of methyl, ethyl, phenyl, vinyl, allyl and hexenyl. 2 Preferably, each is independently selected from the group consisting of H, methyl and ethyl. 3 Preferably each is independently selected from the group comprising ethyl, phenyl, vinyl, allyl and hexenyl.

[0100] According to another embodiment, siloxane is a substitute for amine oil. Based on formula A, the single methyl group in the amine oil is replaced by an amino group. 1 Preferably, each is independently selected from the group consisting of methyl, ethyl, phenyl, 3-aminopropyl and [N-(2-aminoethyl)-3-aminopropyl]. 2 Preferably, each is independently selected from the group consisting of H, methyl and ethyl. 3 Preferably, they are each independently selected from the group comprising ethyl, phenyl, 3-aminopropyl and [N-(2-aminoethyl)-3-aminopropyl].

[0101] Unfunctionalized silica preferably has a particle size of 50-400 m 2 Surface area of ​​g (BET method, see above).

[0102] The unfunctionalized silicon dioxide is reacted with the siloxane of the formula (I) preferably at a temperature of 25 to 400° C., particularly preferably 200 to 400° C. and in particular 200 to 350° C. This temperature is specifically the temperature of the wall of the reactor used.

[0103] The reaction is preferably carried out under standard pressure.

[0104] Unfunctionalized silica is preferably treated with 0.5-5% (based on the mass of silica) of a protic solvent or a weak base (preferably ammonia) prior to functionalization.

[0105] The present invention also includes functionalized silicas prepared by the process, whose D-ring content is less than 250 ppmw, preferably less than 150 ppmw, particularly preferably less than 60 ppmw.

[0106] Another aspect of the present invention relates to the use of the functionalized silica as an additive for controlling the rheology of liquid and powder systems, in particular adhesives and sealants, toners and developers.

[0107] The alkoxy content used for functionalization [O 1 / 2 R 2 ] Less than 3 weight percent of siloxane can be prepared by a process comprising the steps of:

[0108] a) optionally in the presence of an alcohol and / or a solvent, reacting a mixture comprising at least one selected from R1 3SiX、R 1 3SiOR 2 and R 1 3SiOSiR 1 3 silicon compound and at least one selected from SiX4, Si(OR 2 )4、R 1 SiX3、R 1 Si(OR 2 )3. R 3 R 1 SiX2 and R 3 R 1 Si(OR 2 )2, wherein the proportion of water corresponds to at least 50% of the amount of alkoxy groups present in the mixture, wherein X is each independently F, Cl, Br, I, tosylate, triflate or acetate, and the group R 1 、R 2 and R 3 As defined above;

[0109] b) performing phase separation to separate the siloxane phase;

[0110] c) reacting the siloxane phase with a basic catalyst or an acidic catalyst, wherein the reaction with the acidic catalyst is carried out in the presence of at least one silicon compound selected from the group consisting of: 1 3SiOSiR 1 3. R 1 3SiX and R 1 3SiOH;

[0111] d) Removal of low molecular weight components to obtain siloxane.

[0112] The mixture in step a) preferably comprises at least one selected from R 1 3SiX、R 1 3SiOR 2 and R 1 3SiOSiR 1 3 silicon compound and at least one selected from SiX4, Si(OR 2 )4、R 1 SiX3 and R 1 Si(OR 2 )3 silicon compound.

[0113] The reaction in step a) is a cohydrolysis, wherein the reaction is carried out in an excess of water (based on the amount of water required to hydrolyze the alkoxy functions present). This process variant (see Figure 1 , variant A) can be carried out in the presence of an alcohol and / or a solvent, the alcohol being preferably a monohydric or dihydric C1-C 20Alcohol. Particularly preferred are monohydric, unbranched C1-C6 alcohols. In particular, the alcohol is selected from MeOH, EtOH, ethylene glycol, propylene glycol, and combinations thereof. The alcohol may also be optionally present in the solvent.

[0114] The solvent preferably contains at least one compound selected from the group consisting of alcohols, aliphatic compounds, and aromatic compounds, wherein the compound has 1 to 20, preferably 1 to 12, and particularly preferably 1 to 9 carbon atoms. The aromatic compound may be substituted or unsubstituted. Toluene is preferred. The aliphatic compound is preferably an acyclic compound, in particular an n-alkane or an isoalkanes. These may be present as pure substances or as mixtures of isomers.

[0115] Phase separation is used to separate the (preliminary) siloxane obtained by co-hydrolysis in step a) from the aqueous phase optionally containing alcohol. For example, the phase separation can be performed using a separatory funnel or a double column method with a coalescer.

[0116] The Q / T / M siloxanes produced by co-hydrolysis can have a high alkoxy content. This can lead to viscosity instability when exposed to atmospheric moisture. Further chemical treatment can be used to reduce the alkoxy content. The resulting siloxanes are viscosity-stable.

[0117] In step c), the (preliminary) siloxane mixture separated from the aqueous phase is further treated under acidic or basic catalysis. Acidic catalysis (in the presence of (functionalized) disiloxanes, halosilanes or silanols) converts the alkoxy groups into -O-Si(CH3)2R 1 functional groups, while base catalysis converts the alkoxy groups to silanols (which can be condensed or further functionalized).

[0118] In step d), the low molecular weight components are separated, in particular by distillation, for example by means of a distillation column, a thin-film evaporator or a short-path evaporator.

[0119] The molar mass limit of the components to be separated depends on the conditions and compounds used. For example, methanol, ethanol, Si2 (Formula A, if n=1), VSi2 [H2C═C(H)Si(Me)2-O-Si(Me)2(C(H)═CH2)], TM3, and up to QM4 can be removed by distillation. The molar mass limit of the compounds to be separated is, for example, 1000 g / mol, preferably 500 g / mol, and particularly preferably 400 g / mol (QM4=384.84 g / mol).

[0120] Another process variant for preparing the siloxanes used comprises the following steps:

[0121] a) reacting a mixture comprising at least one silicon compound selected from the group comprising SiX4, Si(OR 2 )4、R 1 SiX3、R 1 Si(OR 2 )3. R 3 R 1 SiX2 and R 3 R 1 Si(OR 2 ) 2, wherein the proportion of water corresponds to at least 50% of the amount of alkoxy groups present in the mixture, wherein:

[0122] Each X is independently F, Cl, Br, I, tosylate, triflate or acetate, and the group R 1 、R 2 and R 3 As defined above;

[0123] b) reacting the reaction mixture obtained in step a) with an acidic catalyst in the presence of at least one silicon compound selected from the group comprising: R 1 3SiOSiR 1 3. R 1 3SiX and R 1 3SiOH;

[0124] c) performing phase separation to separate the siloxane phase;

[0125] d) Removal of low molecular weight components to obtain siloxane.

[0126] The mixture in step a) preferably comprises at least one silicon compound selected from the group consisting of SiX4, Si(OR 2 )4、R 1 SiX3 and R 1 Si(OR 2 )3.

[0127] The reaction in step a) is a cohydrolysis, wherein the reaction is carried out with a substoichiometric amount of water and without added M units. This variant (cf. Figure 1 Variant B) allows for specific adjustment of the average chain length of the oligomeric or polymeric alkoxysiloxane forms. The addition of substoichiometric amounts of water minimizes the risk of gelation, but requires chemical reduction of the alkoxy content by further treatment in step b), in which functional groups can also be selectively introduced.

[0128] In step b), the reaction mixture is further treated under acidic catalysis. Here, the alkoxy groups are also converted into -O-Si(CH3)2R 1functional groups.

[0129] With regard to the alcohol, the solvent and with regard to steps c) and d), reference is made to the previous description.

[0130] Preferably, in the above two methods, R 2 Each independently is an unsubstituted C1-C 12 The hydrocarbon group is preferably a C1-C6 hydrocarbon group, and particularly preferably a methyl group or an ethyl group.

[0131] It may be preferred that, in variants A or B above, (see Figure 1 ), R 1 are each independently methyl or phenyl, wherein between steps b) and c), or between steps c) and d), or after step d), a further step i) is carried out, wherein the mixture obtained in each case in the preceding steps is reacted with a basic catalyst in the presence of at least one silicon compound selected from the group comprising: [R 3 Si(OR 2 )3]、[R 3 R 1 Si(OR2)2] and [R 3 3Si(OR 2 )]. R 3 is a group of formula (II):

[0132] -R 4 -[NR 5 -R 6 -] g NR 7 2 (II)

[0133] Group R 4 、R 5 and R 7 The definition is as follows:

[0134] R 4 is a divalent linear or branched hydrocarbon group having 1 to 18 carbon atoms.

[0135] R 5 and R 7 are each independently H, amino, unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, or unsubstituted or substituted C6-C 14 Aryl.

[0136] R 6 is a divalent hydrocarbon radical having 1 to 6 carbon atoms, and the value of the index g is 0, 1, 2, 3 or 4.

[0137] The general formula (II) is derived from the already described R3 A specific selection from the general selection of (aminoalkyl).

[0138] This method variant (see Figure 1 , variant D) is a further workup for the introduction of the amino group.

[0139] The basic catalyst is preferably selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal alkoxides, alkaline earth metal alkoxides, alkali metal silanolates, alkaline earth metal silanolates, amines, aminoalkoxysilanes, and mixtures thereof. The amine is preferably an alkylamine (e.g., triethylamine), an aminosilane, and / or an aminoalkoxysilane (e.g., aminopropylsilane, aminoethylsilane).

[0140] It is also preferred that R 1 are each independently methyl or phenyl, wherein between steps b) and c), or between steps c) and d), or after step d), a further step ii) is carried out, wherein the mixture obtained in each case in the preceding steps is reacted with an acidic catalyst in the presence of at least one silicon compound selected from the group comprising: R 3 3SiOSiR 3 3. R 3 3SiX and R 3 3SiOH. R 3 Each independently is an unsubstituted C2-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 Aryl. R 3 Preferred is vinyl, allyl or hexenyl.

[0141] This variant (see Figure 1 , variant C) is a post-treatment for introducing unsaturated, statistically distributed functional groups.

[0142] Preferably, the acidic catalyst is selected from the group consisting of hydrohalic acid, sulfonic acid, nitric acid, nitrous acid, sulfuric acid, organic acid, and mixtures thereof. The organic acid is preferably at least one compound selected from the group consisting of acetic acid, trifluoroacetic acid, formic acid, propionic acid, oxalic acid, malonic acid, succinic acid, citric acid, malic acid, adipic acid, and mixtures thereof.

[0143] Acidic and basic catalysts can in each case be combined with a support material or used as liquid or gas. Examples of commercially available acidic catalysts are Tonsil (acidic aluminum oxide) or CT269 DR (sulfonic acid).

[0144] Preferably, the reaction is carried out in the presence of an acidic or basic catalyst until thermodynamic equilibrium is established and the composition of the mixture no longer changes.

[0145] The reaction in the presence of an acidic or basic catalyst can be carried out at a temperature of 20-200°C, preferably 50-150°C, particularly preferably 80-120°C.

[0146] Process step a) can be carried out at a temperature of from -20 to 200°C, particularly preferably from 0 to 150°C, in particular from 20 to 120°C.

[0147] The process can be carried out as a batch process, a semi-batch process or a continuous process.

[0148] In principle, the method or individual method steps can be carried out independently of each other under reduced or increased pressure. The pressure is preferably in the range of 1 to 10,000 kPa, particularly preferably in the range of 10 bar to 1,000 kPa. In particular, the method is carried out at ambient pressure.

[0149] The siloxanes produced as described meet the requirements of Regulation (EC) No. 1907 / 2006 (REACH) and can be classified as polymers. Consequently, the siloxanes have a molar mass distribution in which no single component has a content greater than 50%. Furthermore, the siloxanes satisfy the so-called (3n+1) rule, according to which more than 50% of the molecules present in the siloxane have a chain length of 4 or greater, or have a chain length of at least 3 and are covalently bonded to a reactant.

[0150] At room temperature and at the same viscosity, the physicochemical properties of TM, QTM, and QM siloxanes differ significantly from those of DM siloxanes in some respects (particularly in terms of chain length, low-temperature viscosity, and glass transition temperature), but are similar in other respects (refractive index, surface tension), as shown in Table 1.

[0151] Table 1: * Unless otherwise stated, parameters are measured at 25° C. QTM siloxanes consist of equimolar portions of Q and T units.

[0152]

[0153]

[0154] Depending on the choice of functional groups, siloxanes can be used as replacements for polydimethylsiloxanes, D-based vinyl polymers, and D-based amine oils in a wide range of applications.

[0155] Polydimethylsiloxane replacements can be used as damping media, hydraulic fluids, liquid dielectrics (e.g. as transformer fluids), hydrophobing agents (particularly in the automotive care and textile sectors), defoamers, care additives (in the personal and home care sector), lubricants, release agents, plasticizers or heat transfer fluids in the low-temperature range.

[0156] Alternatives to D-based vinyl polymers can be used in coating compositions (e.g., paper coatings), as controlled-release additives, as components in the production of elastomers, or as raw materials for further functionalization by hydrosilylation and epoxidation.

[0157] Alternatives to D-amine oils are used in car care products, mold release agents, textiles, personal / home care, and building protection.

[0158] Figure 1 Shown are schemes for different process variants for the preparation of siloxanes without D-rings. Example

[0159] Reagents

[0160] Tetrachlorosilane (CAS: 10026-04-7), trichloromethylsilane (CAS: 75-79-6), trimethylchlorosilane (CAS: 75-77-4), trimethoxymethylsilane (CAS: 1185-55-3), tetramethoxysilane (CAS: 681-84-5), hexamethyldisiloxane (CAS: 107-46-0), 1,1,3,3-dimethyl-1,3-divinyldisiloxane (CAS: 2627-95-4), 3-aminopropyltrimethoxysilane (CAS: 13822-56-5), and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AS1, CAS: 1760-24-3) were purchased from Sigma-Aldrich. Purchased from Clariant, CT269DR was purchased from Purolite.

[0161] Measurement method

[0162] 1) Viscosity was measured using a Stabinger SVM3000 rotational viscometer from Anton Paar at 25°C and in the temperature range of -40 to 90°C.

[0163] 2) Mass average molar mass M w and the number average molar mass M nThe HPLC-MS / MS was performed by size exclusion chromatography (SEC) in toluene at 35°C at a flow rate of 0.7 mL / min relative to polydimethylsiloxane standards using a MesoPore-OligoPore column set (Agilent, Germany) with a 10 μL injection volume.

[0164] 3) The ratio of Q, T and M units in the siloxane mixture was determined by NMR spectroscopy ( 29 Si-NMR; BrukerAvance III HD 500( 29 Spectrometer (Si: 99.4 MHz) equipped with a BBO 500 MHz S2 probe; reverse gate pulse sequence (NS = 3000)). 150 mg of Q / T / M siloxane mixture was dissolved in 500 μL 4*10 -2 molar Cr(acac)3 in CD2Cl2 solution. 29 Si-NMR data were compared with those from 1 H-NMR spectrum ( 1 H-NMR; Bruker Avance III HD 500( 1 The proportion of other functional groups was determined by correlation with the integral of the spectral range (H: 500.2 MHz) using a BBO 500 MHz S2 probe. 50 mg of the Q / T / M siloxane mixture was dissolved in 500 μL of CD2Cl2.

[0165] 4) Alkyl group content 29 Si- and 1 Combined measurement of H-NMR spectrum (see point 3). 29 Si-NMR spectroscopy allows the determination of the percentages of Q, T, and M units. Taking into account any signal overlap (e.g., MeSiO 3 / 2 group or Me3SiO 1 / 2 Si-Me units of the group), from 29 The relative ratios of Si-NMR spectra can be attributed to 1 The ratio of the H-NMR spectra is used. In this way, the relative proportions of all functional groups (Q, T, M units, alkoxy groups, unsaturated groups, amine groups, etc.) are determined. The relative proportions of the observed substances are multiplied by the molar mass of the respective fragment. The individual masses determined in this way are set relative to the sum of all individual masses. The individual masses of the alkoxy groups relative to the sum of all individual masses multiplied by a factor of 100 give the alkoxy content of the sample, expressed as a percentage by weight.

[0166] 5) Determination of the average empirical formula by a combination of NMR spectroscopy (see point 3) and gel permeation chromatography (GPC, see point 2). 29 Si-NMR spectroscopy allows the determination of the relative molar proportions of Q, T, and M units. Any signal overlap (e.g., MeSiO 3 / 2 group or Me3SiO 1 / 2 Si-Me units of the group), from 29 The relative ratios of Si-NMR spectra can be attributed to 1 The ratio of the H-NMR spectra. In this way, the relative proportions of all functional groups (Q, T and M units, alkoxy groups, unsaturated functional groups, amine functional groups, etc.) are determined. The relative proportions thus obtained are called relative empirical formulas. The relative proportions of the observed substances are multiplied by the molar masses of the respective fragments. The total mass thus obtained is called the relative total mass. According to point 2, the number average molar mass M of the sample to be analyzed is determined by GPC. N Then determine the factor required to convert the relative molar mass to the number-average molar mass. Multiply the relative proportion by this factor. In this way, the relative empirical formula is converted to the average empirical formula.

[0167] 6) The content of unsaturated functional groups in the Q / T / M-based vinyl polymer surrogate is given by the Wijs iodine number, which is measured according to DIN 53241.

[0168] 7) The amine value indicates how many millimoles of KOH are equivalent to one gram of the substance being measured. The amine value is determined according to DIN 16945 Version 1989-03.

[0169] 8) The D-ring content was determined using a gas chromatograph with a flame ionization detector (GC-FID) (CES-Silicones Europe, April 16, 2013 (Revised Version: January 10, 2019)). The detection limit here is typically 60 ppmw.

[0170] 9) The silanol group content can be determined by titration with a 0.1 N sodium hydroxide saturated saline solution (Sears et al., Anal. Chem. 1956, 12. 1981). In the case of silicon dioxide, the hydroxide ion (OH - The relative adsorption capacity can then be defined as the adsorption capacity of the silica under investigation divided by the adsorption capacity of the hydrophilic starting silica multiplied by 100.

[0171] 10) The carbon content was determined at temperatures >1000° C. in an oxygen stream, where the carbon content was determined from the combustion gases by a microprocessor (CS 530, Eltra or SC144DR, Leco).

[0172] 11) The content of volatile components of the functionalized silica was determined in accordance with DIN ISO 787 / 2 at 105° C. and 300° C.

[0173] 12) The thickening effect of the functionalized silica was determined in polyester resins using a rotational viscometer at 25° C. according to DIN 53019.

[0174] Examples 1-3: Preparation of D-ring-free hydrophobic silica by functionalizing fumed silica with T / M siloxanes

[0175] Three types of fumed silica ( V15A, N20, T30, Wacker Chemie AG), the properties of which are shown in Table 2. For the functionalization, a T / M siloxane (S250) with a viscosity of 250 mPa*s and a residual methoxy content of 0.03 wt. % was used.

[0176] Table 2: Silica and siloxanes used

[0177]

[0178] General experimental setup for functionalization:

[0179] In the 6L reactor (quartz glass) being furnished with agitator, 100g silicon-dioxide is fluidized 15 minutes with 800rpm under protective gas (argon).Under constant rotational speed, use gear pump (MCP-Z, Ismatec, Z-1830 pump head), in the nitrogen gas flow of 0.6MPa, in 15 minutes, by gyro spray nozzle (121 type, aperture 0.2mm, 30 ° cone, Schlick) from top feed T / M siloxane (S250).After homogenization 15 minutes, reactor is heated to 300 ℃, and with jacket heater, this temperature is kept 2 hours.In the last 30 minutes of heating period, system is switched to nitrogen purge (100L / h) from argon covering, to discharge volatile component by riser.

[0180] The functionalized silica obtained was analyzed for carbon content, volatile fraction at 105° C. and 300° C., residual silanol content, and thickening effect (rheological properties) in polyester resins. The results are summarized in Table 3.

[0181] Table 3: Analysis results of functionalized silica

[0182]

[0183] Functionalized silica was dispersed in epoxy resin and its rheological properties were tested. After one day of storage, the rheological properties of the functionalized silica were tested at 0.1s. -1 and 10s -1 The viscosity of the mixture was measured at a shear rate of 1000 rpm and 25°C. The thixotropic index was obtained by dividing the low shear viscosity by the high shear viscosity. The thixotropic index of two epoxy resin systems was determined:

[0184] Epoxy resin system 1:

[0185] 8 mol% functionalized silica and 92 mol% epoxy resin (Epikote TM Resin 828 (epoxy resin based on bisphenol A and epichlorohydrin), Hexion).

[0186] Epoxy resin system 2:

[0187] 8 mol% of functionalized silica (according to Examples 1-3) in epoxy resin (Epikote TM Resin 828) and 4 mol% N20 (specific surface area of 200m 2 / g of fumed silica) in an amine hardener (Epikure TM curing agent RIMH-137, Hexion) in a mixture ratio of 79 mol% epoxy resin: 21 mol% amine hardener. For comparison, a conventional, commercially available functionalized silica ( H17). The thixotropic index of the functionalized silica is shown in Table 4.

[0188] Table 4: Rheological tests

[0189]

[0190] The silica modified according to the present invention has the same H17 has considerable shear thickening.

[0191] No D-rings were detected for any of the functionalized silicas according to Examples 1 to 3. Analysis of H17 showed 220 ppm D5 and 70 ppm D6.

[0192] Examples 4-6: Preparation of partially hydrophobic silica without D-ring by functionalizing fumed silica with T / M siloxane Silicon

[0193] The three types of fumed silica used are V15A, N20, T30 (WackerChemie AG), their properties are shown in Table 5. Functionalization was performed with T / M Siloxane S250.

[0194] Table 5: Silica and siloxanes used

[0195]

[0196] The experimental setup and implementation were similar to Examples 1 to 3.

[0197] The functionalized silica obtained was analyzed for its carbon content, its volatile fraction at 105° C. and 300° C., its residual silanol content, and its thickening effect (rheological properties) in polyester resins. The results are summarized in Table 6.

[0198] Table 6: Analysis results of functionalized silica

[0199]

[0200] The synthesis of functionalized T / M siloxane S250, which does not contain a D-ring, was carried out in a 4L three-necked flask equipped with a KPG agitator, a 1L dropping funnel and an olive ring. The flask was connected to two safety wash bottles and an exhaust gas wash bottle containing a 25% NaOH aqueous solution. Before adding the equipment, the equipment was flushed with argon. First, a mixture of 1089g of methanol and 592g of hexamethyldisiloxane was added to the flask and cooled to 0°C. At this temperature, a total of 1335g of methyltrichlorosilane was added over a period of 4 hours through a dropping funnel, and the mixture was heated to 50°C. At this temperature, 602g of softened water was added over a period of 3 hours through a dropping funnel. The mixture was then allowed to reach room temperature (RT) and stirred for 10 hours. A separating funnel was used to separate the siloxane phase from the aqueous methanol phase, neutralized with a saturated sodium bicarbonate solution, and dried over sodium sulfate. After filtration (pleated filter), most of the low-molecular-weight components were removed on a rotary evaporator at 80°C and 10 mbar. The resulting substance was a colorless liquid with a viscosity of 64 mPa*s and a residual methoxy content of 0.03 wt%. Subsequently, further low-molecular-weight components (especially TM3) were removed on a laboratory thin-layer evaporator at 160°C and 10 mbar. The resulting product was a colorless liquid with a viscosity of 250 mPa*s and a residual methoxy content of 0.03 wt%.

[0201] Further production of D-ring-free siloxanes: a universal apparatus for the co-hydrolysis of halosilanes and alkoxysilanes

[0202] A 4 L three-necked flask was equipped with a KPG stirrer, a 1 L pressure-equalizing dropping funnel, and an olive ring. For variants A, B, and C, the flask was connected to two safety wash bottles and an exhaust wash bottle filled with NaOH. Unless otherwise stated, the reagents and solvent (e.g., hexamethyldisiloxane and methanol) were first added to the flask. Before adding the appropriate chlorosilane, the entire apparatus was flushed with argon.

[0203] Figure 1 Various process variants are shown by flow charts. Below, the basic reaction apparatus for carrying out the process variants is first described in general terms. Variants A, B, C and D are then described.

[0204] Choice of reactants

[0205] Halosilanes, alkoxysilanes, disiloxanes, or mixtures thereof can be used as reactants in variant A. In variant C, at least one vinylhalosilane, vinylalkoxysilane, or vinyldisiloxane is also added to the mixture. In variant B, the use of an M source is omitted in the hydrolysis. In variants A and C, an excess of water is used based on the amount of water required to hydrolyze all alkoxy and halogen functional groups present in the mixture. In variant B, a deficit of water is used.

[0206] Cohydrolysis (variants A, B, or C) can be carried out starting with chlorosilanes or methoxysilanes or mixtures thereof. After cohydrolysis, phase separation is carried out in variants A and C. The siloxane phase is then neutralized, dried over sodium sulfate for 2 hours, and separated by filtration. In variant B, the hydrolysis product is used without further processing.

[0207] The products of variants A and B are generally characterized by a residual alkoxy content of >3% by weight. This can be reduced by post-treatment (paths A1, B1, B2, C1). If the residual alkoxy content after variants A or C is already within the desired range, no post-treatment is performed.

[0208] use CT269DR was post-treated (in the presence of (optionally functionalized) disiloxane; Path A1, A2, B1, B2, and C1)

[0209] To a 1L single-neck flask (equipped with a reflux condenser) were added the siloxane to be treated, 7 wt% CT269DR (based on the weight of the siloxane) and a 10-fold molar amount of hexamethyldisiloxane, 1,1,3,3-dimethyl-1,3-divinyldisiloxane, or a mixture thereof (based on the residual alkoxy content in the siloxane). The mixture is heated to 100°C with vigorous stirring for 2 hours, allowed to cool to room temperature, and then separated using a pleated filter (for low-viscosity siloxanes) or a glass filter or glass frit with a suction flask (for high-viscosity siloxanes). For siloxanes with high residual alkoxy content (15-30 mol%) after co-hydrolysis, the catalyst content can be increased to 14 wt%. This post-treatment can reduce the content of TM, QTM, and QM rings in the siloxane.

[0210] use Post-treatment (in the presence of (optionally functionalized) disiloxane; Paths A1, A2, B1, B2 and C1)

[0211] To a 1L three-necked flask (equipped with a reflux condenser) were added the siloxane to be treated, 10 wt% of (based on the weight of the siloxane) and 10 times the molar amount of hexamethyldisiloxane, 1,1,3,3-dimethyl-1,3-divinyldisiloxane or a mixture thereof (based on the residual alkoxy content present in the siloxane). The mixture is heated to 100° C. for a total of 12 hours under stirring, allowed to cool to room temperature, and then separated using a folded filter (for low viscosity fluids) or a glass filter or a glass frit with a suction flask (for high viscosity fluids).

[0212] Post-treatment with HCl (in the presence of an (optionally functionalized) disiloxane; Paths A1, A2, B1, B2 and C1)

[0213] To a stainless steel autoclave (total volume 1 liter, with analog and digital pressure sensors and a resistance jacket heater with a temperature sensor) was added 600 ml of the siloxane to be treated and 10 times the molar amount of hexamethyldisiloxane, 1,1,3,3-dimethyl-1,3-divinyldisiloxane or a mixture thereof (based on the residual alkoxy content present in the siloxane). The autoclave was hermetically sealed and degassed (20 mbar, 3 minutes) and filled with 15 g of hydrogen chloride gas. The autoclave was heated to 100 ° C for 3 hours and then cooled to room temperature. The gas atmosphere was passed through a gas scrubber and the chamber was purged with argon for 5 minutes. The siloxane phase was separated from the alcohol phase, neutralized, dried over sodium sulfate for 2 hours, and filtered.

[0214] Post-treatment with KOH (path A1)

[0215] To a 1 L single-necked flask (equipped with a reflux condenser) was added the siloxane to be treated and an equimolar amount of KOH particles (based on the residual alkoxy content present in the siloxane). The mixture was heated to 100° C. for 2 hours under stirring and then cooled to room temperature. The siloxane phase was neutralized with hydrochloric acid (1 mol / L) and the adhering solids were removed by filtration. The siloxane phase was washed with demineralized water and then dried over sodium sulfate for 2 hours. This post-treatment can be particularly useful for reducing the ring content of Q / T / M siloxanes. The material subjected to this post-treatment still has a residual hydroxyl content even after neutralization, which causes the viscosity to increase with increasing storage time. In order to obtain a material with stable viscosity, a post-treatment with an acidic catalyst can then be performed as described. Due to this post-treatment, the viscosity change of the siloxane can be significant, and in the case of TM siloxanes, reconstruction can usually be detected.

[0216] After each of the above reaction steps, low molecular weight components such as methanol, ethanol, hexamethyldisiloxane, tetrakis(trimethylsiloxy)silane (QM4), for example tris(trimethylsiloxy)methylsilane (TM3) can be removed quantitatively on a rotary evaporator or thin-film / short-path evaporator.

[0217] Treatment with NaOMe in the presence of aminoalkoxysilanes (Variant D)

[0218] In a 1 L round-necked flask with a reflux condenser, the siloxane to be treated is mixed with an aminoalkoxysilane and 500 ppm by weight (based on the total weight) of a sodium methoxide solution (20% by weight in methanol). The mixture is heated to 90° C. for 2 hours while stirring. 29 The reaction was monitored by Si-NMR spectroscopy.

[0219] Reaction sequence

[0220] After the co-hydrolysis (according to variant A), a crude siloxane with a residual alkoxy content is obtained. If this is outside the desired range, it can be reduced by post-treatment using an acidic or basic catalyst (path A1). If the residual alkoxy content is already within the desired range, no post-treatment is performed.

[0221] Siloxanes can be converted into alkenylsiloxanes in a subsequent step (post-treatment with an acidic catalyst, such as 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, Path A2) or aminosiloxanes (post-treatment with NaOMe in the presence of aminoalkoxysilanes). In addition, the introduction of unsaturated functional groups can be combined with a reduction in the residual alkoxy content (Path C1).

[0222] After partial hydrolysis according to variant B, Q-, QT- or T-alkoxy oligomers / polymers are obtained; the M units are not used for the hydrolysis. In the case of post-treatment with acidic catalysts, for example, using hexamethyldisiloxane (path B1), 1,1,3,3-dimethyl-1,3-divinyldisiloxane or mixtures thereof (path B2), (alkenyl)siloxanes are obtained.

[0223] A summary of the reactants used in the examples and their weights used to prepare the crude siloxanes (containing no vinyl or amine functional groups) is given in Table 8.

[0224] Table 8: * Concentrated hydrochloric acid (32 wt%) was used as acid. The acid and demineralized water were mixed before addition and homogenized by vigorous stirring for 5 minutes.

[0225]

[0226]

[0227] The analytical data of the siloxanes before and after post-treatment are summarized in Table 9.

[0228] Table 9: *For Example 19, the crude siloxane from Example 17 was used without workup and reacted according to the above procedure with HCl as catalyst.

[0229]

[0230]

[0231] The weight and analytical data of the functionalized siloxanes are summarized in Table 10.

[0232] Table 10: *The catalyst addition amount of NaOMe solution (20 wt % in MeOH) was 500 ppm by weight (based on the total mass of base siloxane and aminosilane).

[0233]

[0234]

[0235] For Examples 7 to 25, the D-ring content was investigated by GC-FID, and as a result, no D-ring was detected.

Claims

1. Silica functionalized with siloxane of formula (I): [SiO 4 / 2 ] a [R 1 SiO 3 / 2 ] b [R 3 R 1 SiO 2 / 2 ] c [R 1 3SiO 1 / 2 ] d [O 1 / 2 R 2 ] e (I), wherein the indices a, b, c, d, and e each independently have the following integer values: a is 0 to 100, b is 0 to 100, c is 0 to 50, d is 3 to 200, e is 0 to 50, Provided that the sum of a, b and c is at least 1 and, for more than 50% of the siloxane in the mixture, the sum of a, b and c is ≥ 4; where R 1 are each independently H, an amino group, an unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 aryl; where R 2 are each independently H, unsubstituted or substituted C1-C 20 hydrocarbon group; where R 3 are each independently H, an amino group, an unsubstituted or substituted C2-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 Aryl, wherein substituted means that independently of each other there is at least one substituent selected from the group consisting of: OR Y 、-NR Y 2. -SR Y , epoxy, -COOR Y 、-CHO、-CN、-NCO、-OCOOR Y 、-NR Y -COOR Y 、-NR Y -CO-NR Y 、-SiR Y 3and-OSiR Y 3, where R Y are each independently H, an amino group, an unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 Aryl.

2. The silicon dioxide according to claim 1, wherein The indices a, b, c, d, and e each independently have the following integer values: a is 0 to 30, b is 0 to 30, c is 0 to 15, d is 3 to 60, e is 0 to 15.

3. Silicon dioxide as claimed in claim 1 or 2, characterized in that The value of the index a and / or index c is equal to 0.

4. The silicon dioxide according to claim 1 or 2, wherein The D-ring content is less than 250 ppmw.

5. A process for preparing the functionalized silicon dioxide according to claim 1 , wherein unfunctionalized silicon dioxide is reacted with a siloxane of the general formula (I): [SiO 4 / 2 ] a [R 1 SiO 3 / 2 ] b [R 3 R 1 SiO 2 / 2 ] c [R 1 3SiO 1 / 2 ] d [O 1 / 2 R 2 ] e (I), wherein the indices a, b, c, d, and e each independently have the following integer values: a is 0 to 100, b is 0 to 100, c is 0 to 50, d is 3 to 200, e is 0 to 50, Provided that the sum of a, b and c is at least 1 and, for more than 50% of the siloxane in the mixture, the sum of a, b and c is ≥ 4; where R 1 are each independently H, an amino group, an unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 aryl; where R 2 are each independently H, unsubstituted or substituted C1-C 20 hydrocarbon group; where R 3 are each independently H, an amino group, an unsubstituted or substituted C2-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 Aryl, wherein substituted means that independently of each other there is at least one substituent selected from the group consisting of: OR Y 、-NR Y 2. -SR Y , epoxy, -COOR Y 、-CHO、-CN、-NCO、-OCOOR Y 、-NR Y -COOR Y 、-NR Y -CO-NR Y 、-SiR Y 3and-OSiR Y 3, where R Y are each independently H, an amino group, an unsubstituted or substituted C1-C 20 Alkyl, unsubstituted or substituted C2-C 20 Alkenyl, unsubstituted or substituted C6-C 14 aryl; and where R 2 The alkoxy content of ≠H is less than 5 mol%, R 2 The silanol group content of =H is less than 500 ppm, and the viscosity of the siloxane is from 5 to 500,000 mPa*s, as measured at 25° C. using a Stabinger rotational viscometer.

6. The method according to claim 5, wherein The indices a, b, c, d, and e each independently have the following integer values: a is 0 to 30, b is 0 to 30, c is 0 to 50, d is 3 to 60, e is 0 to 15.

7. The method according to claim 5 or 6, characterized in that The value of the index a and / or index c is 0.

8. The method according to claim 5 or 6, characterized in that The siloxanes contain no D-rings.

9. The method according to claim 6, wherein The ratio of the index d to the index b is 0.15 to 3.

10. The method according to claim 6, wherein R 2 Each independently is an unsubstituted C1-C 12 Hydrocarbon group.

11. The method according to claim 6, wherein The surface area of the unfunctionalized silica is 50 to 400 m 2 / g.

12. The method according to claim 6, wherein The reaction is carried out at a temperature of 25 to 400°C.

13. Use of the silicon dioxide according to at least one of claims 1 to 4 or prepared according to the process according to at least one of claims 5 to 12 as an additive for controlling the rheological properties of liquid and powder systems.

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