Process for preparation of hydrogen-containing siloxanes

Abstract

The invention relates to a method for producing hydrogen-containing siloxanes using acid-modified aluminosilicates as equilibrium catalysts, in which a powdered aluminosilicate is applied under mixing to a siloxane mixture consisting of at least two siloxanes and containing at least one SiH-functional siloxane, the acid-modified aluminosilicate is prepared in situ by adding an acid, and the resulting reaction mixture is further mixed for reaction in a balanced sense.

Description

[0001] The present invention belongs to the field of siloxanes. Specifically, the present invention relates to a method for preparing hydrosiloxanes.

[0002] The use of acid-treated bleaching earths, ie acid-treated aluminosilicates, as catalysts in the industrial production of silicone products is known.

[0003] For example, US Pat. No. 2,460,805 teaches the preparation and use of acid-activated bleaching earths for condensing organosiloxanes containing SiOH groups to form polymers of relatively high molar mass. The porous earth or loam minerals used in said document (Florida earth, Kambara earth, bentonite or other hydrous aluminosilicates) have a large specific surface area and are impregnated with an inorganic acid, then dried at 100° C. or even higher and comminuted to the desired particle size in order to subsequently disperse the particles thus obtained in the siloxanols to be condensed. US Pat. No. 2,460,805 teaches simple handling and storage stability of the acid-treated aluminosilicates.

[0004] Likewise, patent document DE 957 662 C (US Pat. No. 2,831,008) deals with the preparation of silicone oils, focusing in Example 4 on the use of an acid-activated neutral washed bleaching earth in the reaction of octamethylcyclotetrasiloxane with hexamethyldisiloxane, wherein octamethyltrisiloxane is formed as the main product.

[0005] For silanol polydiorganosiloxanes with viscosities of 1000 to 10 000 000 centipoise, US Pat. No. 3,903,047 discloses the reaction of low-viscosity liquids bearing silanol groups with cyclic polysiloxanes, wherein a wide range of previously acid-activated aluminosilicates are mentioned as preferred catalysts.

[0006] DE 197 56 832 A1 discloses the use of an acid-activated bleaching earth as a catalyst for the condensation or equilibration of hydroxyl-, alkoxy-, chloro- or triorganosilyl-containing siloxanes with siloxane rings and hexaorganodisiloxanes, the acid-activated bleaching earth being obtained by treating a clay which, as a sheet silicate, is a weathering product of an aluminum oxide-containing rock, wherein a commercially available acid-activated clay ( or ), followed by heating the acid activated clay to 250°C to 1200°C for at least 50 minutes.

[0007] US 3,398,177 describes the redistribution of SiH bonds in the temperature range of 50° C. to 250° C., and teaches that the acidity of the aluminosilicates used in said document can be increased by washing them with a solution of an aqueous strong mineral acid such as HCl or H2SO4 or by treatment with another selected acid followed by heating of the aluminosilicate. However, compared to other acidic solid phases, and even compared to colloidal natural kaolin (c) according to the disclosure of US 3,398,177, the acid-washed kaolin (d) used in Example 12 proved to be only a mild catalyst in the cleavage of dimethylsilane from tetramethyldisiloxane (condensation reaction) at 109° C. within a reaction time of 23 hours (66.4% vs. 89.6% yield).

[0008] DE 44 24 115 A1 discloses a process for preparing linear silicone fluids having low silanol contents and containing triorganosiloxy end groups, wherein acid-treated clay particles are also used.

[0009] US Pat. No. 5,239,101 discloses an anhydrous process for preparing organosiloxy-terminated polyorganosiloxanes from chlorine-terminated polyorganosiloxanes, wherein acidic clays derived from halloysite, kaolinite and bentonite composed of montmorillonite are used as rearrangement catalysts.

[0010] In a slightly different vein, US Pat. No. 5,233,070 discloses the use of acidic clays also as catalysts for the preparation of polyorganocyclosiloxanes starting from chlorine-terminated polyorganosiloxanes.

[0011] US 5,068,383 is devoted to the rearrangement of linear, chlorine-terminated or hydroxyl-terminated polyorganosiloxanes with cyclic polyorganosiloxanes and describes the use of acid-treated clays as rearrangement catalysts.

[0012] US 4,895,967 describes a process for preparing cyclic poly(siloxanes) by reacting a cyclic poly(siloxane) with an acidic clay at a temperature of 200° C. to 800° C. and advantageously with an auxiliary vacuum. The cyclic organohydrogensiloxane and the linear hydrogen-containing siloxane are thermally separated by contact.

[0013] US 4,831,174 discloses the use of acid-activated clays to prepare triorganosilyl-terminated polydiorganosiloxane fluids in a continuous process. US 4,230,816 discloses the equilibration of siloxanes with (alkylthio) or mercaptoalkyl groups in the presence of an acid catalyst. In addition to a series of liquid strong acids, and (Filtrol Corporation) as acid treated clay.

[0014] GB 922,377 describes phyllosilicates and chain silicates for preparing organohydrogenpolysiloxanes and shows that certain previously acid-activated, as well as some non-acid-activated aluminosilicates (calcium bentonite in Example 3, sodium bentonite in Example 4, attapulgite "Floridin" in Example 5, all as above) are suitable for preparing α,ω-dihydropolydimethylsiloxanes. For bleaching earths previously activated with acid, they are washed to neutrality after acid treatment and then dried at about 200° C. In comparative experiments for equilibrating tetramethyldisiloxane with octamethylcyclotetrasiloxane, it was shown according to GB 922,377 that concentrated sulfuric acid as a catalyst only caused an incomplete reaction after heating at 50° C. for 5 hours. After a further reaction time of 5 hours, the tetramethyldisiloxane was first brought to a boil under reflux at 71° C. and then the temperature was raised to 100° C., and equilibrium was reached, but with a clear loss of valuable SiH functional groups. According to GB 922,377, similar experiments using kaolin as catalyst showed that even after heating to 150° C. no loss of hydrogen was recorded, but the reaction was still incomplete.

[0015] The disclosure of CN 103524743A is devoted to the preparation of hydrogenated silicone oils with SiH end groups by polymerization, and describes the reaction of hydrogenated polysiloxanes and cyclosiloxanes with siloxanes with SiH end groups under the action of an acid catalyst such as acid-activated clay with the addition of an organic solvent, and then the production of a two-phase material system by the introduction of water. The acidified aqueous phase is removed, and the introduction of water and the removal of the acid-containing aqueous phase are repeated 4 times. In addition to the solvent, the organic phase also contains hydrogenated silicone oils with SiH end groups, unreacted hydrogenated polysiloxanes and siloxane rings, i.e., the siloxane matrix disclosed in CN 103524743A is absolutely not an equilibrium. Laborious vacuum distillation at a pressure of 0.095 MPa and 180° C. is necessary to separate the hydrogenated silicone oils with SiH end groups after the removal of volatiles.

[0016] The prior art also describes the preparation of acid-activated aluminosilicates.

[0017] For example, W. Gao, S. Zhao, H. Wu, W. Deligeer and S. Asuha, “Direct acid activation of kaolinite and its effects on the adsorption of methylene blue”, Applied Clay Science 126 (2016), 98-106, p. 99, supra, state that it is difficult to activate natural kaolin minerals by acid treatment because the material is inactive, and therefore heat treatment at a temperature of 600° C. to 800° C. is necessary prior to acid treatment.

[0018] This view is also supported by significantly earlier documents in the prior art, which are related to methods for preparing acid-activated kaolin clay, such as US 2,477,664, in which the kaolin clay is first granulated and then calcined at 566° C. for 2 hours. This is followed by an acid treatment with 15% hydrochloric acid and a pressurized water treatment in an autoclave at 232° C.

[0019] In order to further illustrate the technical complexity involved according to the prior art, reference should be made here to, for example, the article "Effect of sulphuric acid treatment on the physico-chemical characteristics of kaolin clay" by AK Panda, BG Mishra, DK Mishra, RK Singh in Colloid and Surfaces A: Physicochem. Eng. Aspects 363 (2010), 98-104, in which the authors heated the natural kaolin to be activated in a reflux condenser at 110° C. with 10 times the amount of sulfuric acid for 4 hours, then quenched with ice water, filtered, washed several times with distilled water, dried in an oven and then calcined at 500° C. for 1 hour in order to finally convert it into powder form using a mortar and pestle.

[0020] US 2,470,872 teaches the preparation of acid-activated aluminosilicates (sub-bentonites), focusing on the preparation of acid-activated montmorillonites, wherein the high temperature acid treatment is followed by quenching in cold water, washing until free of acid and salts, filtering, drying and grinding (Example 1 in said document). The teaching of this document represents one of the so-called "wet" processes.

[0021] To this end, as a further reference to obtaining acid-activated aluminosilicates according to the prior art, reference should also be made to the teaching of the examined and published application DE 1 063 127, which describes a process for converting kaolin clay into a technically usable, adsorptive contact composition and employs a so-called "dry" process, which allows the aluminosilicate to be not washed off after the acid treatment is completed, but to be calcined directly, so that the overall chemical composition of the clay thus remains unchanged.

[0022] Despite the success achieved so far with acid-activated aluminosilicates in siloxane chemistry, the fundamental tendency of these catalysts to undergo framework modifications during storage, especially under non-inert conditions, has proven to be disadvantageous for industrial use. Aging phenomena, which are also accelerated by normal air humidity, can lead to irreversible framework rearrangements in previously acid-treated aluminosilicates within a few days.

[0023] For example, the study by CN Rhodes and DR Brown, “Autotransformation and Ageing of Acid-treated Montmorillonite Catalysts: A Solid-state 27 Al NMR Study" (J. Chem. Soc. Faraday Trans., 1995, 91 (6), 1031-1035), which focused specifically on the stability behavior of acid-treated montmorillonites and showed that the disadvantage of these materials lies in their inherent instability, which leads to changes in their chemical and physical properties during aging. Elemental analysis and solid state 27 The combined use of Al NMR (magic-angle spinning NMR) allows a deeper understanding of the aging process of acid-treated montmorillonites, since it is possible to at least 27 Al NMR readily distinguishes between octahedral and tetrahedral coordinated oxygen-aluminum centers. For the investigations, commercially available acid-treated montmorillonites (Fulcat 22A and low-iron Texas montmorillonite from Laporte) were used, each of which was treated in the form of a 1% suspension with rapid stirring at 95°C with 30% by volume sulfuric acid, followed by washing with deionized water and drying at 60°C. CN Rhodes and DR Brown in the study discussed clearly showed that during the acid treatment of montmorillonite clay, ion exchange occurs, in which Al 3+ and other metal cations are protonated (H + ) are replaced. As a result, the clay minerals accumulated layer by layer gradually delaminate and their ability to act as cation exchangers decreases. The main aging process is believed to be H + Exchange clay self-converts to Al 3+ Exchange (and to some extent Mg 2+ and Fe 3+ exchange) form of clay, where H + The ions migrate into the solid lattice and the metal ions migrate to the exchange sites. This self-conversion can even occur under the aggressive conditions of the acid treatments carried out industrially, especially at elevated temperatures for relatively long periods of time, and, as the authors CN Rhodes and DR have convincingly demonstrated, during storage of acid-activated montmorillonites, (high) humidity promotes this self-conversion, so that a loss of ion exchange capacity and acidity is to be expected.

[0024] In particular, it is this unforeseeable loss of acidity that makes the use of acid-treated aluminosilicates, preferably acid-treated montmorillonites, a major uncertainty factor in the industrial production (equilibrium), in particular of demanding hydrogen-bearing siloxanes.

[0025] Depending on the desired target structure of the respective hydrogen-bearing siloxane, the effective acidity in the balanced system is crucial.

[0026] For example, the SiH function-maintaining equilibration of siloxanes with dimethylhydrosiloxy groups and methylhydrosiloxy units in the equilibration matrix is ​​by far the greatest challenge, and therefore superacids such as perfluoroalkanesulfonic acids, especially trifluoromethanesulfonic acid and perfluorobutanesulfonic acid, remain the preferred homogeneous catalysts for the industrial equilibration of these specific hydrogen-containing siloxanes.

[0027] The difficulty in balancing these unbranched hydrogen-containing siloxanes with dimethylhydrogensiloxy groups and also containing methylhydrogensiloxy and dimethylhydrogensiloxy groups is to achieve a substantially very uniform statistical distribution of the SiH functionalities along the oligomer chain without losing too many sensitive dimethylhydrogensiloxy groups by dehydrogenation processes or dimethylsilane cleavage.

[0028] In contrast to perfluorinated superacids, the effective acidity of acid-treated aluminosilicates and, for example, sulfonic acid ion exchange resins in a siloxane matrix containing SiH groups is significantly lower, so that it is very important to find the right reaction parameters for the respective equilibrium system when using these catalysts.

[0029] The desired acidity is specifically guided by the equilibrium task to be achieved, ie by the structure of the desired hydrogen-containing siloxane. The synthesis of α,ω-dihydropolydimethylsiloxanes places minimal demands on the acidity of the catalyst, ie its proton-donating capacity.

[0030] If, for example, a mixture of octamethylcyclotetrasiloxane and tetramethyldisiloxane is converted to α,ω-dihydropolydimethylsiloxane under acid catalysis, then theoretically only one proton is required to open the octamethylcyclotetrasiloxane molecule, which is initiated by protonation of the oxygen atom in the SiOSi bond present therein.

[0031] Likewise, for example, only one proton is theoretically required to open the SiOSi bond present in the tetramethyldisiloxane molecule. The regulation of the oligomer chain distribution additionally requires a relatively low proton activity.

[0032] However, for example, for those containing methylhydrogensiloxy units (D units) in addition to trimethylsilyl groups (M units), HFor copolysiloxanes which contain SiOSi units (SiOSi units) and dimethylsiloxy units (D units) and which are prepared, for example, from poly(methylhydrogen)siloxane, octamethylcyclotetrasiloxane and hexamethyldisiloxane under acid catalysis, the conditions are completely different. Theoretically, only one proton is required to open an octamethylcyclotetrasiloxane molecule after protonation of the oxygen atom in one of the four SiOSi bonds present therein. Likewise, only one proton is theoretically required to initiate the opening of the SiOSi bonds present in a hexamethyldisiloxane molecule. Theoretically, the molecular decomposition of poly(methylhydrogen)siloxane also requires only one proton per siloxane bond (SiOSi bond) in each case. However, in order to achieve a statistical distribution of methylhydrogensiloxy units along the oligomeric chains of, for example, the desired poly(methylhydrogensiloxane)-polydimethylsiloxane copolymers, more protons are required per volume of reaction mass, especially within the customary time windows of industrial silicone production, since only the nearly simultaneous breaking and reconnection of multiple SiOSi bonds can produce a copolymer without any methylhydrogensiloxy units (=D H Unit) accumulation.

[0033] This purely statistical theoretical consideration of the acidity required to balance such siloxane copolymers is supported by the experiments of the publication “Functional polysiloxanes. I. Microstructure of poly(hydrogenmethylsiloxane-co-dimethylsiloxane)s obtained by cationic copolymerization” by G. Sauvet, M. Moreau. G. Hélary, E. Daudet, P. Cancouet in J. Polymer Science, Part A: Polymer Chemistry, Vol. 38, 826-36 (2000), in which the authors (p. 833, supra) draw the clear conclusion that the two D H The reactivity of the siloxane bond (SiOSi) between the units is lower than that between two D units, which directly affects some reactions involved in the acid balance, such as backbiting, cross-linking and acidolysis.

[0034] The accumulation of methylhydrogensiloxy groups should preferably be avoided as far as possible, since the subsequent use of the hydrogen-containing siloxane equilibria in hydrosilylation reactions, in particular in those reactions in which polyether mixtures are used to obtain polyether siloxanes for demanding surfactant applications, for example as stabilizers in polyurethane foams, is directly related to the structural features of the copolymers, which have polyether-bearing Si atoms which are distributed as statistically as possible on the oligomer chain, i.e. are separated from one another as far as possible, since they are separated from one another by the D units.

[0035] G. Sauvet et al. (page 835, right column, supra) in the previously mentioned publication (see above; J. Polymer Science, Part A: Polymer Chemistry Vol. 38, 826-36 (2000)) concluded that understanding the relationship between D and D in the chain H The distribution of the units is key to understanding the properties of the (SiH) copolymers themselves and, more importantly, the properties of the functionalized derivatives derived from them. The authors note that in the case of hydrosilylation, D and D H The distribution of units in the chain has a direct influence on the reaction rate.

[0036] In this context, in the article “Functional polysiloxanes.II.Neighboring effect in the hydrosilylation of poly(hydrogenmethylsiloxane-co-dimethylsiloxane)s by allyl glycidyl ether” in J. Polymer Science, Part A: Polymer Chemistry, Vol. 38, 837-45 (2000), P. Cancouet, S. Pernin, G. Hélary, G. Sauvet studied the neighboring group effect of the hydrosilylation addition of allyl glycidyl ether to poly(methylhydrogensiloxane)-polydimethylsiloxane copolymers and demonstrated that the methylhydrosiloxy diades (D H -D H ) leads to accelerated hydrosilylation, while the separated D H Unit, that is, D surrounded by D units H Unit (DD H -D) exhibits slower reaction kinetics.

[0037] Against the background of this finding, it is obvious to the person skilled in the art that the microstructure of the hydrogen-containing siloxanes, in particular in the case of addition to polyether mixtures having a respective reactivity range, has a significant influence on the subsequent target structure of the polyether siloxane copolymers.

[0038] Methods for determining the fine structure of molecules in hydrogen-containing siloxanes are known. For example, in the above-mentioned publication (see above; J. Polymer Science, Part A: Polymer Chemistry Vol. 38, 826-36 (2000)), G. Sauvet et al. used, inter alia, high resolution29 Si NMR spectroscopy was used to detect the accumulation of diads, triads, pentads, etc., ie, methylhydrogensiloxy groups, in the poly(methylhydrogensiloxane)-polydimethylsiloxane copolymer.

[0039] However, to date, NMR technology has not gained a foothold in the industrial production of polyorganohydrogensiloxanes as an in-process analysis method, especially as a real-time method, due to factors including the cost of the equipment to be installed and, in particular, the fundamental problem of accommodating extremely strong electromagnetic radiation sources such as NMR magnets and measuring heads in an operationally safe manner in explosion-proof production equipment.

[0040] The teaching of WO2022 / 132446A1 attempts to solve the problem of process analysis by using (particularly supported by the examples therein) vibrational spectroscopy such as infrared spectroscopy and Raman spectroscopy to determine the presence of siloxanes acting as a D source and siloxanes acting as a D source. H The structures of the siloxanes from the source are directly related to each other in the acid-catalyzed equilibrium (D H -D H ) and separate structures (DD H -D) in order to assess the degree of distribution achieved. Focusing on the curing rate in silicone elastomers, a direct relationship was observed between the concentration of decoupled (i.e., statistically distributed) SiH groups determined by vibrational spectroscopy and the curing kinetics when each SiH copolymer was used. For example (ibid., page 18, Table 3), the first batch of SiH copolymers required 144.3 seconds to fully cure after a 3-hour equilibration time and a SiHIR intensity of 2.08 after introduction into the elastomer system, while the 7th batch of SiH copolymers had already led to the curing of the elastomer system after only 61.4 seconds after a 16-hour equilibration time and a SiH IR measured intensity of 3.32.

[0041] In particular, with regard to various cure systems (condensation- and / or hydrosilylation cure products) as target products, the method proposed in WO 2022 / 132446 A1 is intended to help minimize batch times while achieving higher statistical uniformity of the equilibrium SiH copolymers.

[0042] In particular, against the background art mentioned above, the present invention relates to the preparation of hydrogen-containing siloxanes, particularly preferably those with a substantially very uniform statistical distribution of SiH functional groups, with side groups SiH in the form of methylhydrogensiloxy and dimethylhydrogensiloxy groups, as well as dimethylsiloxy and preferably trimethylsilyl groups. In particular, taking into account the disadvantages of the above-mentioned acid-activated aluminosilicates that lack aging resistance, the object of the present invention is to provide a further process for the preparation of hydrogen-containing siloxanes using a balanced catalyst, preferably taking into account the balance of hydrogen-containing siloxanes with dimethylhydrogensiloxy groups, unbranched and containing methylhydrogensiloxy groups and dimethylsiloxy groups, preferably having an average structural formula according to formula (1):

[0043]

[0044] In order to preferably achieve a substantially very uniform statistical distribution of the SiH functional groups along the oligomer chain, preferably without losing too many sensitive dimethylhydrogensiloxy groups due to dehydrogenation processes or dimethylsilane cleavage, in formula (1):

[0045] 0≤x≤200, preferably 20≤x≤160, particularly preferably 30≤x≤80,

[0046] 1≤y≤30, preferably 2≤y≤26, particularly preferably 2≤y≤10,

[0047] 0.4≤a≤1.0, preferably 0.6≤a≤0.95,

[0048] 0≤b≤0.6, preferably 0.05≤b≤0.4,

[0049] a+b=1,

[0050] Particularly preferably, x+y+2≥13.

[0051] Surprisingly, the inventors of the present invention have found that equilibration of hydrogensiloxanes, preferably of the abovementioned structural type, can be carried out in a reliably reproducible manner if pulverulent aluminosilicates are added to the corresponding siloxane mixtures, in order to prepare the acid-modified aluminosilicates in situ by addition of acid, and the reaction mixture is then reacted.

[0052] The present invention, which achieves the above-mentioned objects, provides a process for preparing hydrogen-containing siloxanes using an acid-modified aluminosilicate as an equilibrium catalyst, preferably in the absence of water and solvent, wherein a powdered aluminosilicate, preferably a powdered kaolin, is added with mixing to a siloxane mixture consisting of at least two siloxanes and containing at least one SiH-functional siloxane, and the acid-modified aluminosilicate is prepared in situ by adding an acid, preferably an inorganic acid, in particular concentrated sulfuric acid, to form a reaction mixture, which is then reacted in the sense of equilibrium by further mixing, preferably heating, preferably until the equilibrium of the desired hydrogen-containing siloxane has been achieved.

[0053] Hydrogen-containing siloxanes are SiH-functional siloxanes, ie siloxanes which carry at least one SiH functional group, preferably at least two SiH functional groups.

[0054] According to the invention, preferably the siloxane mixture consists of at least two different siloxanes which together have methylhydrogensiloxy, dimethylhydrogensiloxy and dimethylsiloxy groups, preferably trimethylsilyl groups, wherein particularly preferably usable siloxanes are, for example, poly(methylhydrogen)siloxanes, tetramethylcyclotetrasiloxane, hexamethyldisiloxane, decamethylcyclopentasiloxane (D5), octamethylcyclotetrasiloxane, tetramethyldisiloxane and / or α,ω-dihydropolydimethylsiloxane.

[0055] The solution according to the invention is completely surprising since, in contrast to the invention, previous documents in the prior art focus on the use of acid-activated aluminosilicates for equilibration of hydrogen-containing siloxanes, describing a procedure in which a previously acid-activated aluminosilicate is applied to a siloxane matrix for equilibration, wherein the previously acid-activated aluminosilicate is usually washed to neutrality after the acid treatment and / or also dried and / or calcined and / or pulverized and / or formulated.

[0056] It is even more surprising to the person skilled in the art that the in situ acid modification according to the invention of the pulverulent aluminosilicate used, preferably carried out under very mild conditions in a siloxane matrix, leads to such a high level of equilibrium activity that even after very short reaction times a substantially very uniform statistical distribution of the SiH functional groups along the oligomeric chains of the hydrogen-containing siloxanes can be achieved without, preferably in the case of hydrogen-containing siloxanes comprising dimethylhydrogensiloxy, methylhydrogensiloxy and dimethylsiloxy groups, too much loss of the sensitive dimethylhydrogensiloxy groups as a result of dehydrogenation processes or dimethylsilane cleavage.

[0057] In the context of the present invention, what was particularly unforeseeable from the literature for the preparation of acid-activated aluminosilicates according to the above-mentioned prior art was the ease and speed with which a pulverulent aluminosilicate, preferably pulverulent kaolin, introduced into the siloxane matrix for equilibration acquires its activity as an equilibration catalyst under the action of an acid, preferably an inorganic acid, particularly preferably concentrated sulfuric acid.

[0058] The invention or the process according to the invention for preparing hydrogen-containing siloxanes, in which the acid modification of the aluminosilicate is carried out exclusively in a siloxane matrix, i.e. in a siloxane mixture consisting of at least two siloxanes and containing at least one SiH-functional siloxane, advantageously not only enables a consistently high equilibrium activity of the catalyst in the production of hydrogen-containing siloxanes, but also has a positive effect with regard to the potential health hazard of charging or applying the pulverulent aluminosilicates, for example, to industrial equilibrium reactors. When handling pulverulent aluminosilicates which have not been acid-modified, the respiratory and skin protection required for production personnel is much simpler. In the case of the particularly preferred pulverulent kaolin, it should also be noted in this context that kaolin was approved for use in the food industry before January 31, 2014 in the functional category "carrier substances, release agents and emulsifiers" under the European approval number E559.

[0059] The invention can dispense with complex process steps such as pickling, neutral washing, drying or even calcining or sintering, making the method according to the invention advantageous from the perspective of resource conservation. Energy- and resource-consuming process steps can thus be avoided.

[0060] According to the invention, it is particularly preferred to carry out the equilibration for preparing the hydrogen-containing siloxanes substantially, i.e. preferably to carry out the equilibration according to the invention in the absence of water and solvent, i.e. preferably without the use of solvents, in particular without the use of organic solvents, and preferably without the addition of water. However, small amounts of water may be present, originating from the acid used according to the invention and / or from the pulverulent aluminosilicate used according to the invention, and may amount in total to ≤5% by mass, preferably ≤4% by mass, based on the total amount of these two starting materials.

[0061] According to the invention, pulverulent aluminosilicates are used. Powdered aluminosilicates are known to the person skilled in the art. Powdered aluminosilicates which can preferably be used according to the invention have a particle size of preferably less than 250 micrometers, preferably less than 100 micrometers, particularly preferably less than 80 micrometers. The particle size can be determined using known particle size determination methods, preferably using known laser diffraction methods, preferably assuming spherical particle geometry.

[0062] A powdered aluminosilicate used very particularly preferably according to the invention is powdered kaolin, preferably naturally occurring powdered kaolin (CAS 1332-58-7), also known as china clay.

[0063] Powdered kaolins are known per se to the person skilled in the art. This preferably includes all those powdered clay minerals which contain kaolinite, halloysite, dickite, nacrite and / or anauxite as main clay minerals in the unfired state, with kaolinite being particularly preferred and being a particularly preferred main component of kaolin. Kaolinite can preferably be described by the following known idealized formula: Al2O3·2SiO2·2H2O.

[0064] Powdered aluminosilicates, preferably powdered kaolin, are commercially available. For example, the corresponding powdered kaolin is available under the trade name Speswhite TM Commercially available from IMERYS Minerals Ltd., United Kingdom.

[0065] According to the invention, preferably a total amount of 0.3% to 1.5% by weight, further preferably a total amount of 0.5% to 1.4% by weight, particularly preferably a total amount of 0.75% to 1.35% by weight, of pulverulent aluminosilicate, preferably pulverulent kaolin, is used, based on the total amount of the siloxane mixture.

[0066] According to the invention, an acid, preferably an inorganic acid, particularly preferably concentrated sulfuric acid, is used in a total amount of preferably 30 to 2500 ppm by weight, particularly preferably in a total amount of 100 to 1500 ppm by weight, based on the total amount of the siloxane mixture (ppm by weight = fraction by weight in ppm (ppm = parts per million)).

[0067] Concentrated sulfuric acid is known to those skilled in the art. It preferably has a sulfuric acid content of at least 96% by weight, particularly preferably at least 98% by weight.

[0068] As already explained, the pulverulent aluminosilicate is added to the siloxane mixture with mixing and the acid-modified aluminosilicate is prepared in situ by addition of the acid, after which the reaction mixture is reacted in the sense of equilibrium with further mixing and preferably heating.

[0069] According to the invention, equilibration is preferably carried out in a temperature range of 25 to 95° C., particularly preferably in a temperature range of 40 to 80° C. According to the invention, equilibration is preferably carried out in 4 to 12 hours, particularly preferably in 6 to 9 hours.

[0070] Preferably, at the end of the equilibration, the reaction mixture is neutralized, preferably with sodium bicarbonate, preferably in an amount of 0.25% to 1.0% by weight, based on the amount of the total siloxane mixture, and preferably water is added, preferably in an amount of 100 to 600 ppm by weight, based on the amount of the total siloxane mixture, preferably over a period of 1 to 6 hours.

[0071] According to the invention, preferably after addition of a filter aid, the neutralized reaction mixture is separated from the solids, preferably by filtration, and the equilibrated hydrogen-containing siloxanes are isolated.

[0072] Filter aids which can preferably be used are chemically inert substances which can support the filtration process solely due to physico-mechanical effects; preferably, treated or untreated cellulose, silica gel, diatomaceous earth and / or perlite can be used.

[0073] According to the present invention, if the obtained balanced hydrogen-containing siloxane conforms to the following average structural formula (Formula 1), it is preferred

[0074]

[0075] in:

[0076] 0≤x≤200, preferably 20≤x≤160, particularly preferably 30≤x≤80,

[0077] 1≤y≤30, preferably 2≤y≤26, particularly preferably 2≤y≤10,

[0078] 0.4≤a≤1.0, preferably 0.6≤a≤0.95,

[0079] 0≤b≤0.6, preferably 0.05≤b≤0.4,

[0080] a+b=1,

[0081] Particularly preferably, x+y+2≥13.

[0082] A further subject matter of the present invention is a hydrogen-containing siloxane preparable, preferably prepared, by the process according to the invention, preferably according to any one of claims 1 to 12 .

[0083] A further subject of the present invention is the use of the hydrogen-containing siloxanes preparable according to the invention as co-reactants in a hydrosilylation reaction for preparing a hydrosilylation product, wherein the hydrosilylation reaction is preferably carried out in the presence of a noble metal catalyst and at least one unsaturated organic compound, preferably a terminally unsaturated organic compound, preferably a terminally unsaturated olefinic compound, which may optionally also carry further substituents; particularly preferred unsaturated organic compounds are terminally unsaturated polyethers, allyl glycidyl ethers, glycerol Monoallyl ethers, allyl glycols, allyloxyethanol, allyl anisole, allyl phenol, eugenol, hexenol, C6-C20 olefins, undecenoic acid and / or vinylcyclohexene monoxide; even further preference is given to terminally unsaturated polyethers, allyl glycols, tetradecene, hexadecene, octadecene and / or methyl undecenoate, with very particular preference being given to the use of terminally unsaturated polyethers, such as allyl-functional polyethers and / or methallyl-functional polyethers, particular preference being given to the use of terminally unsaturated allyl polyethers.

[0084] A further subject matter of the present invention is the use of the hydrosilylation products preparable according to the invention:

[0085] (a) as surfactant, as dispersing additive, defoamer, wetting aid, hydrophobizing agent and / or crosslinking additive, preferably in pastes, paints, varnishes, overcoats, coatings and / or coating agents,

[0086] (b) in cleaning and / or care formulations which are suitable for cleaning and / or caring for hard surfaces and / or for cleaning, treating and / or after-treating textiles, and in cosmetics,

[0087] (c) as foam stabilizers or foam additives for polyurethane foams,

[0088] or

[0089] (d) as adjuvants for improving the effect of plant protection active ingredients and / or as carriers for plant protection active ingredients, wherein the plant protection active ingredients are preferably selected from microbial plant protection active ingredients.

[0090] The following examples are only used to further illustrate the present invention and do not constitute any limitation to the present invention. Example:

[0091] In the context of the present invention, the measured values ​​were recorded in a Bruker Avance III spectrometer at a measuring frequency of 79.49 MHz. 29Si NMR spectra, the spectrometer was equipped with a 287430 sample head with a gap width of 10 mm, dissolved in CDCl3 at 22°C, and tetramethylsilane (TMS) was used as an external standard [d( 29 Si)=0.0ppm].

[0092] The china clay used in the examples of the present invention (Speswhite TM , Imerys Minerals Ltd.) is a powdered kaolin mined from deposits in southwest England.

[0093] Example 1 (according to the present invention)

[0094] The balance according to the invention is directed to the following average hydrogen-containing siloxane structure:

[0095]

[0096] Where x=36.85, y=3.15, a=0.92, and b=0.08.

[0097] For this purpose, 99.18 g of poly(methylhydrogen)siloxane (SiH value determined by the gas-volume method: 15.6 mol / kg), 1077.51 g of decamethylcyclopentasiloxane (D5) and 323.32 g of α,ω-dihydropolydimethylsiloxane (SiH value determined by the gas-volume method: 2.8 mol / kg) were first charged into a 2000 ml four-necked flask, which had been previously inertized with argon and equipped at the top with a precision glass paddle stirrer, an internal thermometer and a reflux condenser, and then 19.5 g of china clay (1.3 wt. % of Speswhite, based on the total siloxane mass) were added and stirred. TM ) and 1.5 g (0.82 ml) of concentrated sulfuric acid (99 wt%) (1000 wt ppm based on the total siloxane mass). The well-stirred reaction mixture was heated to 60° C. for 7 hours, and the target viscosity of 40 mPas was reached after 4 hours (sampling).

[0098] After 7 hours, 7.5 g of sodium bicarbonate (5000 wt ppm based on the total siloxane mass), 0.45 g of deionized water (300 wt ppm based on the total siloxane mass) and 19.5 g of filter aid ( 900). Neutralization was carried out for a total of 4 hours before the solid components were separated using a filter press (K 450 filter disc). A drop of the resulting clear filtrate showed a neutral reaction on a moist universal test paper. A small amount of the filtrate was taken out and 29 Si NMR spectroscopy was performed to analyze the structure of the desired hydrogen-containing siloxane.

Claims

1. A method for preparing hydrogen-containing siloxane using an acid-modified aluminosilicate as an equilibrium catalyst, characterized in that: The pulverulent aluminosilicate is added to a siloxane mixture consisting of at least two siloxanes and containing at least one SiH-functional siloxane with mixing, and the acid-modified aluminosilicate is prepared in situ by adding an acid, thereby forming a reaction mixture, which is then reacted by further mixing in the sense of equilibrium.

2. The method according to claim 1, characterized in that The siloxane mixture consists of at least two different siloxanes which together have methylhydrogensiloxy, dimethylhydrogensiloxy and dimethylsiloxy groups, preferably trimethylsilyl groups.

3. The method according to claim 1 or 2, characterized in that: The equilibration is performed in the absence of water and solvent.

4. The method according to any one of claims 1 to 3, characterized in that As the powdery aluminosilicate, powdery kaolin was used.

5. The method according to any one of claims 1 to 4, characterized in that Based on the total amount of the siloxane mixture, a total amount of 0.3% to 1.5% by weight, preferably 0.5% to 1.4% by weight, particularly preferably 0.75% to 1.35% by weight, of pulverulent aluminosilicate, preferably pulverulent kaolin, is used.

6. The method according to any one of claims 1 to 5, characterized in that Acids, preferably mineral acids, particularly preferably concentrated sulfuric acid, are used in a total amount of 30 to 2500 ppm by weight, preferably 100 to 1500 ppm by weight, based on the total amount of the siloxane mixture.

7. The method according to any one of claims 1 to 6, characterized in that The equilibration is performed in a temperature range of 25°C to 95°C, preferably in a temperature range of 40°C to 80°C.

8. The method according to any one of claims 1 to 7, characterized in that The equilibration is carried out within 4 to 12 hours, preferably within 6 to 9 hours.

9. The method according to any one of claims 1 to 8, characterized in that At the end of the equilibration the reaction mixture is neutralized, preferably with sodium bicarbonate and water is added, preferably for 1 to 6 hours.

10. The method according to claim 9, characterized in that The neutralized reaction mixture is separated from the solids, and the equilibrated hydrogenosiloxane is isolated, preferably by filtration, more preferably after addition of a filter aid.

11. The method according to any one of claims 1 to 10, characterized in that The method is used to prepare an unbranched hydrogen-containing siloxane having dimethylhydrogensiloxy, methylhydrogensiloxy and dimethylsiloxy groups, preferably trimethylsilyl groups.

12. The method according to any one of claims 1 to 11, characterized in that The resulting balanced hydrogen-containing siloxane conforms to the following average structural formula (Formula 1): Formula 1, in: 0≤x≤200, preferably 20≤x≤160, particularly preferably 30≤x≤80, 1≤y≤30, preferably 2≤y≤26, particularly preferably 2≤y≤10, 0.4≤a≤1.0, preferably 0.6≤a≤0.95, 0≤b≤0.6, preferably 0.05≤b≤0.4, a+b=1, Particularly preferably, x+y+2≥13.

13. Hydrogen-containing siloxanes preparable, preferably prepared, by the process according to any one of claims 1 to 12.

14. Use of the hydrosiloxane according to claim 13 as a coreactant in a hydrosilylation reaction for preparing a hydrosilylation product, wherein the hydrosilylation reaction is preferably carried out in the presence of a noble metal catalyst and at least one unsaturated organic compound, preferably a terminally unsaturated organic compound, preferably a terminally unsaturated olefinic compound, which may optionally also carry further substituents, particularly preferably terminally unsaturated polyethers, allyl glycidyl ether, glycerol monoallyl ether, allyl glycol, allyloxyethanol, allyl anisole, allyl phenol, eugenol, hexenol, C6-C20 olefins, undecenoic acid and / or vinyl cyclohexene monoxide, even further preferably terminally unsaturated polyethers, allyl glycol, tetradecene, hexadecene, octadecene and / or methyl undecenoate, wherein very particular preference is given to using terminally unsaturated polyethers such as allyl-functional polyethers and / or methallyl-functional polyethers, and particular preference is given to using terminally unsaturated allyl polyethers.

15. Use of the hydrosilylation product according to claim 14: (a) as surfactant, as dispersing additive, defoamer, wetting aid, hydrophobizing agent and / or crosslinking additive, preferably in pastes, paints, varnishes, lacquers, coatings and / or coating compositions, (b) in cleaning and / or care formulations which are suitable for cleaning and / or caring for hard surfaces and / or for cleaning, treating and / or after-treating textiles, and in cosmetics, (c) as foam stabilizers or foam additives for polyurethane foams, or (d) as adjuvants for improving the effect of plant protection active ingredients and / or as carriers for plant protection active ingredients, wherein the plant protection active ingredients are preferably selected from microbial plant protection active ingredients.

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