Preparation of acid-free hydrosiloxane counterweights

Abstract

The invention relates to a method for producing an acid-free hydrosiloxane balance, in which a mixture comprising at least two different siloxanes having together dimethylhydrosiloxy, methylhydrosiloxy, dimethylsiloxy and preferably trimethylsiloxy groups is contacted with a macroporous cross-linked aqueous cation exchange resin containing sulfonic acid groups, the invention relates to a method for producing an acid-free hydrosiloxane counterbalance, comprising the steps of adding an acid-free hydrosiloxane counterbalance produced in this way to at least one unsaturated polyether having an arithmetic mean HLB value of > 9.0, calculated by the incremental method of Guo, by means of noble metal-catalyzed hydrosilylation, and reacting in the form of a rearrangement of SiOSi bonds until the acid-free hydrosiloxane counterbalance produced in this way is added to at least one unsaturated polyether having an arithmetic mean HLB value of > 9.0, which is clear at T = 25 DEG C, by means of noble metal-catalyzed hydrosilylation, wherein the rearrangement of the SiOSi bonds is carried out in the temperature range of 10 to 50 DEG C, with the proviso that the cation exchange resin is characterized in that the product P of its specific surface area and its average pore size is P > = 2.2 x 10-3 m3 / kg and the specific surface area A is > = 35 m2 / g, and in addition, the water content is 6 to 16 wt%, based on the weight of the cation exchange resin.

Description

Technical Field

[0001] This invention belongs to the field of silicone chemistry, and specifically relates to a method for preparing acid-free, unbranched hydrosiloxane equilibrium products. Background Technology

[0002] Hydrosiloxanes, i.e. siloxanes with SiH groups, play an important role, especially as balancing agents and precursors, for example, in further processing to obtain polyether siloxanes, silicone acrylates, silicone quaternary ammonium salts, silicone waxes and many other derivatives.

[0003] The equilibrium of siloxanes is largely known from existing technologies. In recent years, in addition to the oldest equilibrium methods carried out by homogeneous catalysis, heterogeneous catalysis methods have been increasingly used in the industrial production of silicones using solid-phase catalysts.

[0004] One example of the significant advantages of acidic solid-phase catalysts in the production of hydrosiloxanes is that the liquid siloxane phase can be separated from the acidic solid-phase catalyst without complex post-treatment, and in particular without the need to neutralize the homogeneous acid, which would otherwise typically be used and the resulting salts removed by filtration.

[0005] Macroporous sulfonated polystyrene resins are of particular significance in solid-phase catalysts used for hydrosiloxane equilibration. They have been found to be especially suitable for equilibrating siloxane systems with siloxane components containing methylhydrosiloxy groups.

[0006] To achieve this objective, for example, the teachings of WO 2010 / 031654 A1 specifically relate to the equilibration of poly(methylhydro)polydimethylsiloxane copolymers on an aqueous cation exchange resin, wherein an organosiloxane or a mixture of organosiloxanes used as a starting material is contacted with a macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups at a temperature of 10°C to 120°C, and the resulting equilibrated organosiloxane is separated. The aqueous cation exchange resin used according to WO 2010 / 031654 A1 is characterized in that the product of its specific surface area and its average pore size, P, is P ≥ 2.2 × 10⁻⁶. -3 m 3 / kg and specific surface area A is >35m² 2 / g, and additionally, based on the weight of the ion exchange resin, its water content is 8 to 25% by weight. To address the water consumption in sulfonic acid cation exchange resins, WO2010 / 031654A1 teaches that it may be advantageous to add a defined amount of water to the reactant system.

[0007] WO 2010 / 074831 A1 describes a process for the preparation of siloxanes comprising the conversion of at least two siloxanes in the presence of an ion exchange resin catalyst comprising 6 to 19 wt.-% of water, wherein at least one of the siloxanes comprises silicon-bonded hydrogen atoms, and wherein preferably at least one of the siloxanes is a poly(hydro)methylsiloxane or a cyclic siloxane. In particular, it describes the reaction of at least two siloxanes on an aqueous ion exchange resin catalyst, wherein at least one of the siloxanes comprises silicon-bonded hydrogen atoms, and wherein after the reaction the ion exchange resin catalyst is recovered and the water loading of 6 to 19 wt.-%, based on the dry weight of the ion exchange resin catalyst, is established by adding water to the ion exchange resin catalyst, and then at least two siloxanes are converted again in the presence of this ion exchange resin catalyst. The reactants selected in the examples of WO 2010 / 074831 A1 are octamethylcyclotetrasiloxane and tetramethyldisiloxane, and in this case the content of octamethylcyclotetrasiloxane (D4) in the siloxane matrix at the end of the reaction, determined by gas chromatography, is considered to be an indicator of the establishment of equilibrium. Furthermore, the SiH content is determined only at the beginning of the reaction with reference to the reaction mixture. However, WO 2010 / 074831 A1 does not give any data on the SiH content of the reaction mixture at the end of each reaction. However, the SiH content of the reaction product is even more important in addition to the D4 content determined via gas chromatography, since this reference parameter is required for all further reactions of the building blocks (such as hydrosilylation or dehydrogenation reactions) to determine the respective stoichiometry.

[0008] DE 102014211680 A1 describes the preparation of siloxanes, preferably with non-regenerative reuse of ion exchange resins, which comprises the reaction of at least two siloxanes on a sulfonic acid cation exchange resin using at least one OH-functional siloxane. In the examples of DE 102014211680 A1, alpha, omega-dihydro polydimethylsiloxanes and decamethylcyclopentasiloxane are used. In the context of the present disclosure, it is shown that a number of sulfonic acid cation exchange resins are suitable for the equilibration of alpha, omega-dihydro polydimethylsiloxanes which undergo SiOSi rearrangements. However, although all acid-equilibratable siloxanes are claimed, the document does not show how to obtain equilibrated (i.e. highly homogeneously distributed) SiH siloxanes which simultaneously have chain end and pendant SiH functionalities.

[0009] The equilibration of siloxanes which simultaneously carry dimethylhydrogensiloxy and methylhydrogensiloxy units in the equilibrated matrix is the greatest challenge to date, so superacids such as perfluoroalkanesulfonic acids, in particular triflic acid and perfluorobutanesulfonic acid, are still the preferred homogeneous catalysts for the industrial equilibration of these specific hydrosiloxanes.

[0010] However, it is foreseeable that the possibility of utilizing the already described highly efficient homogeneous catalysts will only be possible within a limited time frame. European chemical regulations are currently working on the elimination of perfluorinated alkane sulfonic acids, so it can currently be assumed that, for example, the homogeneous catalysts such as triflic acid and perfluorobutanesulfonic acid which are tried and tested in silicone production will no longer be available in the future.

[0011] In the balance of the preferred unbranched hydrocarbonsiloxanes with dimethylhydrogensiloxy groups and also with methylhydrogensiloxy and dimethylsiloxy groups, the difficulty lies in achieving a substantially statistical uniform distribution of the SiH functional groups along the oligomer chain without too much sensitive dimethylhydrogensiloxy groups being lost as a result of the dehydrogenation process.

[0012] In comparison with perfluorinated superacids, sulfonic ion exchange resins have significantly lower effective acidity in siloxane matrices containing SiH groups, so it is very important to find suitable reaction parameters for the respective equilibrium system when using sulfonic ion exchange resins.

[0013] Here, the required acidity is determined in particular by the equilibrium task to be achieved, i.e. by the structure of the desired hydrocarbonsiloxane. The acidity imposed on the catalyst, i.e. its ability to provide protons, by the synthesis of α,ω-dihydro-polydimethylsiloxanes is minimal. If, for example, a mixture consisting of octamethylcyclotetrasiloxane and tetramethyldisiloxane is converted into α,ω-dihydro-polydimethylsiloxane under acid catalysis, then, in theory, only one proton is required to open the octamethylcyclotetrasiloxane molecule, which is initiated by the protonation of the oxygen atom in the SiOSi bond present therein. The same is true for the SiOSi bond present in the tetramethyldisiloxane molecule, in theory, only one proton is required to open it. The adjustment of the oligomer chain distribution additionally requires a relatively low proton activity.

[0014] However, for those containing methylhydrogensiloxy units (D HThe situation is completely different for copolysiloxanes which contain both methylhydrogensiloxy units (M units) and dimethylsiloxy units (D units) and which can be prepared, for example, from poly(methylhydrogen)siloxane, octamethylcyclotetrasiloxane and hexamethyldisiloxane under acid catalysis. 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, theoretically, only one proton is required to initiate the opening of a SiOSi bond present in a hexamethyldisiloxane molecule. Theoretically, also only one proton is required for the molecular decomposition of a poly(methylhydrogen)siloxane, per siloxanyl bond (SiOSi bond). However, in order to achieve a statistical distribution of the methylhydrogensiloxy units along the oligomer chains of the desired poly(methylhydrogen)siloxane-polydimethylsiloxane copolymer within the time window of the reaction, a higher number of protons per unit volume of the reaction mass is required, since only the almost simultaneous breaking and reforming of multiple SiOSi bonds can lead to a copolymer which does not accumulate any methylhydrogensiloxy units (= D units) within the siloxane oligomer chains. H The situation is completely different for copolysiloxanes which contain both methylhydrogensiloxy units (M units) and dimethylsiloxy units (D units) and which can be prepared, for example, from poly(methylhydrogen)siloxane, octamethylcyclotetrasiloxane and hexamethyldisiloxane under acid catalysis. 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, theoretically, only one proton is required to initiate the opening of a SiOSi bond present in a hexamethyldisiloxane molecule. Theoretically, also only one proton is required for the molecular decomposition of a poly(methylhydrogen)siloxane, per siloxanyl bond (SiOSi bond). However, in order to achieve a statistical distribution of the methylhydrogensiloxy units along the oligomer chains of the desired poly(methylhydrogen)siloxane-polydimethylsiloxane copolymer within the time window of the reaction, a higher number of protons per unit volume of the reaction mass is required, since only the almost simultaneous breaking and reforming of multiple SiOSi bonds can lead to a copolymer which does not accumulate any methylhydrogensiloxy units (= D units) within the siloxane oligomer chains.

[0015] The greatest challenge is considered to be the controlled acid-catalyzed preparation of a hydrosiloxane having methylhydrogensiloxy units, dimethylhydrogensiloxy units and dimethylsiloxy units and, preferably, a small proportion of trimethylsiloxy end groups. Here, the aim is to ensure the broadest possible statistical distribution of the methylhydrogensiloxy units along the oligomer chains, but at the same time to ensure that, in particular, the sensitive dimethylhydrogensiloxy groups do not undergo any associated hydrogen loss.

[0016] In the specific disclosure of this type of hydrosiloxane, the teaching of DE 102005001039 A1 relates to the establishment of a suitable equilibration of the specific sulfonic acid cation exchange resin, but does not achieve a statistical distribution of the SiH functionality in the hydrosiloxane obtained.

[0017] Specifically, DE 102005001039 A1 also describes a process for preparing a SiH group-containing equilibration product of organosiloxanes by rearranging siloxane bonds on a sulfonic acid cation exchange resin, in which an organosiloxane or organosiloxane mixture used as starting material and a hydrosiloxane are contacted at a temperature of from 10 to 120°C with a macroporous, crosslinked cation exchange resin containing sulfonic acid groups, and the organosiloxane thus obtained is isolated by using a cation exchange resin, the product of the multiplication of the specific surface area of which by its average pore diameter, P, being P < 2.2 x 10 -3 m 3 / g and the specific surface area A being < 50 m 2 / g.

[0018] To obtain a non-sticky coating composition, DE 102005001039 A1 relates to the preparation of organopolysiloxanes containing (meth)acrylate groups, which are obtained by dehydrogenative conversion of (meth)acrylated alcohols, such as hydroxyethyl acrylate, with these organosiloxanes being essentially penetrated by SiH domains and B(C6F5)3 as catalyst.

[0019] For comparison purposes, DE 102005001039 A1 refers to a hydrosiloxane, which uses decamethylcyclopentasiloxane (D5), poly(methyl)hydrosiloxane and a, co-dihydrogen polydimethylsiloxane (HSiMe2-[SiMe2O]8-SiMe2H), mixed with 0.1% triflic acid and equilibrated at 30°C for 6 hours with continuous stirring, and then neutralized with Na2CO3.

[0020] However, these statistically uniformly distributed hydrosiloxanes obtained under triflic acid catalysis and their derivatives with (meth)acrylate groups are not suitable for the purpose of DE 102005001039 A1.

[0021] Since according to the teachings given therein, the statistical distribution of the SiH functionality in the obtained hydrosiloxanes is not the purpose, it is not possible to infer from DE 102005001039 A1 any precise specification as to which cation exchange resin and under which reaction conditions such a statistically uniformly distributed hydrosiloxane of this structural type can be prepared, which is only possible under triflic acid catalysis.

[0022] EP 1 439 200 A1 describes a process for the preparation of an equilibrated product of organosiloxanes by rearranging siloxane bonds on a sulfonic acid cation exchange resin, wherein an organosiloxane or a mixture of organosiloxanes used as starting material is contacted with a macroporous crosslinked cation exchange resin containing sulfonic acid groups at a temperature of 10°C to 120°C and the resulting equilibrated organosiloxane is isolated by using a cation exchange resin having a product of the specific surface area and the average pore diameter P of P > 2.2 x 10 -3 m 3 / kg and a specific surface area A of > 35 m 2 / g. In EP 1 439 200 A1, the starting materials used are in particular mixtures of hexamethyldisiloxane, poly(methyl)hydrosiloxanes and siloxane ring bodies. By way of example, one of the preparations described therein is the preparation of a hydrosiloxane using decamethylcyclopentasiloxane, poly(methyl)hydrosiloxane and hexamethyldisiloxane by equilibration at a temperature of 95°C. Evaluation of the nuclear magnetic resonance spectrum leads to the conclusion that the resulting product has predominantly single SiH fragments in a statistical arrangement.

[0023] The published specification DE 21 52 270 A describes a process for the preparation of an equilibrium product of organosiloxanes by rearranging siloxane bonds on a cation exchange resin, in which an organosiloxane or an organosiloxane mixture used as starting material is flowed through a packing at temperatures of about 10°C to about 100°C, which contains as cation exchange resin a macroporous crosslinked cation exchange resin containing sulfonic acid groups and having an average pore volume of at least about 0.01 cm 3 and is separated from the eluted organosiloxanes. In the findings described therein, it is possible to use methylhydrogenosiloxane, dimethylsiloxane and mixtures of organosiloxanes selected from hexamethyldisiloxane and symmetrical tetramethyldisiloxane. One of the possibilities described therein is the preparation of copolydimethylsiloxane poly(methyl)hydrogenosiloxane by equilibrating a mixture consisting of methylhydrogenpolysiloxane, hexamethyldisiloxane and siloxane ring bodies on a macroporous crosslinked 15ion exchanger phase.

[0024] EP 2 628 763 A1 discloses a process for the preparation of branched polysiloxanes having olefinically unsaturated groups and SiH groups, preferably using acidic ion exchange resins having sulfonic acid groups.

[0025] However, for the preparation of hydrogenosiloxanes consisting of dimethylhydrogenosiloxy units, methylhydrogenosiloxy units and dimethylsiloxy units and possibly a small proportion of trimethylsiloxy end groups, no technical instructions are given, since on the one hand they have methylhydrogenosiloxy units, which are more robust in terms of SiH loss, but on the other hand they also have dimethylhydrogenosiloxy units, which undergo severe SiH loss even under relatively mild conversion conditions.

[0026] In this context, by the evaluation of the inventors, none of the documents cited in the prior art teaches how to produce an equilibrated hydrogenosiloxane with a statistically distributed distribution of SiH groups therein and with pendant SiH groups in the form of methylhydrogenosiloxy and dimethylhydrogenosiloxy groups and dimethylsiloxy groups and preferably a small proportion of trimethylsiloxy end groups, very substantially preserving the hydrogen originating from the dimethylhydrogenosiloxy groups in a reproducible manner and with sulfonic acid cation exchange resins.

[0027] This purely statistical theoretical consideration of the acidity required to equilibrate such siloxane copolymers is supported experimentally in the publication G. Sauvet, M. Moreau, G. Hélary, E. Daudet, P. Cancouet, "Functional polysiloxanes. I. Microstructure of poly(hydrogenmethylsiloxane-co-dimethylsiloxane)s obtained by cationic copolymerization" published in J. Polymer Science, Part A: Polymer Chemistry Vol. 38, 826-36 (2000), where the authors (p. 833, ibid.) draw the explicit conclusion that the reactivity of the siloxane bond between two D H units is lower than the reactivity of the siloxane bond between two D units, which directly influences the partial reactions involved in the acid equilibration, such as backbiting, crosslinking and acidolysis.

[0028] The accumulation of methylhydrogensiloxy groups should be avoided as far as possible, since the subsequent use of the hydrosiloxane equilibrates in hydrosilylation reactions, in particular those in which polyether mixtures are used to obtain polyethersiloxanes for high- demand surfactant applications, for example as stabilizers in polyurethane foams, is directly related to the structural feature of the copolymer with polyether-containing Si atoms, which are as randomly distributed as possible on the oligomer chain, i.e. as far apart from each other as possible, since they are separated from each other by D units.

[0029] In the above-mentioned publication, Sauvet et al. (p. 835, right column, ibid.) draw the conclusion that, for a chain with D and D H units distributed in the chain, the distribution of the D and D H units in the chain has a direct influence on the reaction speed of the hydrosilylation reaction.

[0030] In this context, P. Cancouet, S. Pernin, G. Hélary, G. Sauvet in their article "Functional polysiloxanes. II. Neighboring effect in the hydrosilylation of poly(hydrogen methylsiloxane-co-dimethylsiloxane)s by allyl glycidyl ether" in J. Polymer Science, Part A: Polymer Chemistry, Vol. 38, 837-45 (2000) investigated the neighboring group effect in the hydrosilylation of poly(hydrogen methylsiloxane)-co-dimethylsiloxane)s by allyl glycidyl ether and demonstrated that the presence of methylhydrogensiloxy diads (D H -D H ) leads to an acceleration of the hydrosilylation, whereas isolated D H units, i.e. those D H units which are surrounded by D units (D-D H -D) exhibit a slower reaction kinetics. In the context of this finding, it is obvious to the person skilled in the art that the microstructure of the hydrogenosiloxane, in particular in the case of the addition of polyether mixtures having a respective reactivity range, has a significant influence on the subsequent target structure of the polyether siloxane copolymer.

[0031] Methods for the determination of the molecular fine structure of hydrogenosiloxanes are known. For example, in the already cited publication J. Polymer Science, Part A: Polymer Chemistry Vol. 38, 826-36 (2000), G. Sauvet et al. in particular use high-resolution 29 Si NMR spectroscopy to detect diads, triads, pentads etc. in poly(hydrogen methylsiloxane)-co-dimethylsiloxane)s, i.e. the accumulation of methylhydrogensiloxy groups.

[0032] However, NMR technology has hitherto not found a place in the industrial production of polyorganohydrogenosiloxanes as a process analytical method, in particular as a real-time method, due to factors including the cost of the equipment to be installed and, in particular in explosion-proof production plants, the fundamental problem of accommodating sources of extremely strong electromagnetic radiation such as NMR magnets and measuring heads in an operationally safe manner.

[0033] The teachings of WO 2022 / 132446 A1 seek to solve the problem of in-process analysis by using, in particular supported by the examples therein, vibrational spectroscopy methods such as infrared spectroscopy and Raman spectroscopy to determine the degree of statistical homogeneity of the structures (D-D H directly related to each other in the acid catalyzed equilibrium of siloxanes acting as D source and siloxanes acting as D H -D H and mutually isolated structures (D-D H -D) in order to assess the degree of distribution achieved. Focusing on the cure rate in siloxane elastomers, a direct relationship is observed between the concentration of uncoupled (i.e. statistically distributed) SiH groups determined by vibrational spectroscopy and the cure kinetics when using the respective SiH copolymer. For example (ibid., page 18, table 3), the SiH copolymer from lot 1 required 144.3 seconds to fully cure after an equilibration time of 3 hours in the elastomer system and a SiH IR intensity of 2.08, whereas the SiH copolymer originating from lot 7 already led to the curing of the elastomer system after only 61.4 seconds after an equilibration time of 16 hours and a SiH IR measured intensity of 3.32. The method proposed in WO 2022 / 132446 A1 is said to facilitate the minimization of the lot processing time while achieving a higher statistical homogeneity of the equilibrated SiH copolymer for various different curing systems (condensable cured products and / or hydrosilylation curable products), in particular as target products. SUMMARY

[0034] Preferably, with regard to higher silicone polyether copolymers useful in rigid polyurethane foam stabilizers, for example, the present invention relates inter alia to providing specific acid-free hydrosiloxane equilibrates and preferably further inter alia to detecting a highly statistically homogeneous distribution of SiH functionality in hydrosiloxanes having pendant SiH groups in the form of methylhydrogensiloxy and dimethylhydrogensiloxy groups and dimethylsiloxy groups and preferably a small fraction of trimethylsiloxy groups. Providing specific acid-free hydrosiloxane equilibrates and preferably further detecting a highly statistically homogeneous distribution of SiH functionality are specific objects of the present invention. In the context of the present invention, a statistically homogeneous distribution of SiH functionality means that all methylhydrogensiloxy groups present in the reaction system are distributed over the chains of the hydrosiloxane equilibrates such that, averaged over the entire chain length distribution of the hydrosiloxane, preferably the presence of methylhydrogensiloxy groups is neither under- nor over-provided and such that preferably a substantial avoidance of accumulation, i.e. an adjacent arrangement of methylhydrogensiloxy groups in the siloxane chain, is achieved.

[0035] The present inventors have now surprisingly found that said acid-free hydrosiloxane equilibrates can be prepared on a macroporous crosslinked water-containing cation exchange resin containing sulfonic acid groups, wherein said cation exchange resin is characterized in that the product of its specific surface area and its average pore diameter P is P > 2.2 x 10 -3 m 3 / kg and a specific surface area A of > 35 m 2 / g and, in addition, a water content of 6 to 16% by weight, preferably 8 to 12% by weight, based on the weight of the cation exchange resin.

[0036] The present inventors have also surprisingly found that the person skilled in the art, without the use of the above-mentioned complex instrumental analysis, can make a reliable assessment of whether the equilibration reaction carried out in the respective hydrosiloxane mixture has resulted in a highly statistically uniform distribution of the copolymer or in the penetration of the copolymer by the methyl hydrogen siloxy domains in the hydrosiloxane phase by visual inspection of the selected polyether siloxane.

[0037] These findings are surprising and unforeseeable for the person skilled in the art, since the old patent literature dealing with the equilibration incorporation of dimethyl hydrogen siloxy groups into siloxane skeletons of different structure discloses, when cation exchange resins of this type are used for this purpose, a considerable hydrogen loss of Si-bonded hydrogen (SiH) in some cases. This is shown very clearly, for example, by working examples 2, 3 and 4 of EP 2 628 763 A1 on the SiH loss experienced with equilibration systems using dimethyl hydrogen groups on sulfonic acid cation exchange resins (K2621). In this case, a sulfonic acid resin having a water content of 10% was allowed to act on mixtures consisting of branched and linear hydrosiloxanes, which each contained sensitive dimethyl hydrogen siloxy groups, for 6 hours at 40°C, and siloxanes having only 66%, 82% and 75% of the amount of SiH originally used were isolated. K2621) using dimethyl hydrogen groups. In this case, a sulfonic acid resin having a water content of 10% was allowed to act on mixtures consisting of branched and linear hydrosiloxanes, which each contained sensitive dimethyl hydrogen siloxy groups, for 6 hours at 40°C, and siloxanes having only 66%, 82% and 75% of the amount of SiH originally used were isolated.

[0038] The subject matter of the present invention enables the above-mentioned specific objects. The present invention provides a process for the preparation of an acid-free hydrosiloxane equilibration product of the following average structural formula:

[0039]

[0040] wherein

[0041] 3 < x < 100, preferably 30 < x < 80,

[0042] 1 < y < 30, preferably 2 < y < 10,

[0043] 0.4 < a < 1.0, preferably 0.6 < a < 0.95,

[0044] 0 < b < 0.6, preferably 0.05 < b < 0.4,

[0045] a + b = 1,

[0046] more preferably x + y + 2 > 13,

[0047] wherein a mixture comprising at least two different siloxanes collectively having dimethylhydrogensiloxy groups, methylhydrogensiloxy groups, dimethylsiloxy groups and preferably trimethylsiloxy groups

[0048] contacting with a macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups and reacting in a rearrangement of SiOSi bonds until the acid-free hydrogensiloxane equilibrant produced in this way is added to at least one unsaturated polyether by means of a noble metal catalysed hydrosilylation addition to give a clear addition product at T = 25 °C, the preferred arithmetic mean HLB value calculated by Guo's increment method of the unsaturated polyether being > 9.0,

[0049] wherein the rearrangement of SiOSi bonds is carried out in a temperature range from 10 to 50 °C,

[0050] with the proviso that the macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups is characterized in that the product of its specific surface area and its average pore diameter P is P > 2.2 x 10 -3 m 3 / kg and the specific surface area A is > 35 m 2 / g and, in addition, its water content is 6 to 16% by weight, based on the weight of the cation exchange resin.

[0051] It is particularly preferred when the rearrangement of SiOSi bonds is carried out in a temperature range from 30 °C to 40 °C.

[0052] The rearrangement of SiOSi bonds is preferably carried out in a time period of 4 to 10 hours, preferably 5 to 8 hours.

[0053] Preferably, according to the process of the application, it is particularly preferred that the rearrangement of SiOSi bonds is carried out at a pressure of preferably 800 mbar to 1200 mbar, more preferably 950 mbar to 1100 mbar.

[0054] It is preferred when the macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups is characterized in that the product of its specific surface area and its average pore diameter P is P > 2.3 x 10 -3 m 3 / kg, further preferably > 2.4 x 10 -3 m 3 / kg.

[0055] The macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups preferably has an average pore diameter of at least 65 nm.

[0056] According to the application, in the process for the preparation of an acid-free hydrogensiloxane equilibrant, a mixture comprising at least two different siloxanes collectively having dimethylhydrogensiloxy groups, methylhydrogensiloxy groups, dimethylsiloxy groups and preferably trimethylsiloxy groups is used.

[0057] Thus, the mixture comprising at least two different siloxanes contains a SiH-functional siloxane. A SiH-functional siloxane is a siloxane having at least one SiH functional group, i.e. one or more than one SiH functional group.

[0058] In the context of the present application, the usable siloxanes having dimethylsiloxy and methylhydrogensiloxy groups are more preferably those containing a small fraction of trimethylsiloxy groups, as they can preferably be prepared using poly(methylhydrogen)siloxanes, which are available in sufficient industrial quantities and whose chain ends are terminated by trimethylsiloxy groups.

[0059] Siloxanes suitable according to the teachings of the present application to provide methylhydrogensiloxy groups are, for example, 2,4,6,8-tetramethylcyclotetrasiloxane (D4 H ), one of the specialty chemicals which are less available industrially, but which are likewise preferably used.

[0060] Any siloxane having at least one SiH functional group can preferably be used, preferably those in which the SiH functional group is in pure terminal, pure pendant or mixed pendant and terminal positions in the siloxane.

[0061] The SiH-functional siloxane used can preferably be a higher homolog, such as 1,1,1,3,5,5,5-heptamethyltrisiloxane and / or a linear poly(methylhydrogen)siloxane terminated by trimethylsiloxy groups, such as HMS-993 from Gelest Inc. (Gelest Inc., Morrisville, Pennsylvania, USA), additionally such as a linear polydimethylmethylhydrogensiloxane copolymer, such as HMS-031 and / or HMS-071 from Gelest Inc., additionally such as a linear a,co-dihydrogenpolydimethylsiloxane, such as 1,1,3,3-tetramethyldisiloxane, 1,1,3,3,5,5-hexamethyltrisiloxane and / or a higher homolog, such as DMS-HM15, DMS-H03, DMS-H25, DMS-H31 and / or DMS-H41 from Gelest Inc., additionally such as a cyclic poly(methylhydrogen)siloxane, such as tetramethylcyclotetrasiloxane and / or pentamethylcyclopentasiloxane, additionally such as a cyclic polydimethylmethylhydrogensiloxane copolymer, such as heptamethylcyclotetrasiloxane and / or nonamethylcyclopentasiloxane, or any mixture thereof.

[0062] The SiH-functional siloxane used can more preferably be poly(methylhydrogen)siloxane, 1,1,3,3-tetramethyldisiloxane, DMS-H03, HMS-993 (each from Gelest Inc.) and / or pentamethylcyclopentasiloxane.

[0063] The SiH-functional-free siloxanes used can preferably be, for example, linear polydimethylsiloxanes, such as hexamethyldisiloxane, or, for example, cyclic polydimethylsiloxanes, such as octamethylcyclotetrasiloxane and / or decamethylcyclopentasiloxane, more preferably hexamethyldisiloxane and / or decamethylcyclopentasiloxane.

[0064] In particular, it is preferred when the mixture comprising at least two different siloxanes collectively having dimethylhydrogensiloxy, methylhydrogensiloxy, dimethylsiloxy and preferably trimethylsiloxy groups comprises at least one a, w-dihydrogenpolydimethylsiloxane and at least one poly(methylhydro)siloxane, preferably at least one poly(methylhydro)siloxane terminated with trimethylsiloxy groups. This is particularly preferred when the siloxane mixture used additionally contains at least one cyclic siloxane, preferably selected from octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6).

[0065] The previously obtained poly(methylhydro)siloxane-polydimethylsiloxane copolymer with dimethylhydrogensiloxy groups, preferably the acid-free hydrogen siloxane equilibration product, is preferably reacted with at least one unsaturated polyether, preferably with a polyether mixture consisting of at least two unsaturated polyethers, under noble metal catalysed hydrosilylation conditions and the reaction is visually assessed for whether it produces a visually clear addition product.

[0066] The at least one unsaturated polyether to be used here, preferably the mixture consisting of at least two unsaturated polyethers, has an HLB value of greater than 9.0, which is calculated by the increment system introduced by Guo et al. (Calculation of hydrophile-lipophile balance for polyethoxylated surfactants by group contribution method in J. Colloid Interface Sciences 298, (2006), 441-450). When a plurality of unsaturated polyethers is used, i.e. when a mixture consisting of at least two unsaturated polyethers is used, the arithmetic mean HLB value (HLB = hydrophilic-lipophilic balance) of the unsaturated polyethers used is > 9.0.

[0067] In the case of polyether siloxanes consisting of different polyethers, the arithmetic mean HLB value can preferably be obtained by multiplying the molar percentage of each polyether used in the respective polyether siloxane formulation by its respective HLB value calculated according to the Guo system and then adding up these results for all polyethers present in the polyether siloxane.

[0068] In the context of the present invention, turbid addition products, which are polyether siloxanes, show the presence of domains, while clear addition products show a highly statistically uniform distribution.

[0069] This finding applies to polyether siloxanes derived from hydrosiloxanes having pendant SiH groups in the form of methylhydrogensiloxy and dimethylhydrogensiloxy groups and, preferably, a small proportion of trimethylsiloxy groups, and dimethylsiloxy groups.

[0070] This visual assessment can also be used when the hydrosiloxane to be assessed is intended, for example, for a completely different hydrosilylation modification than the conversion to a polyether siloxane.

[0071] Preferably, during the process for preparing an acid-free hydrosiloxane equilibrium according to the invention, a sample of the hydrosiloxane to be assessed is removed from the reaction mixture and this sample is reacted under noble metal catalysed hydrosilylation conditions with at least one unsaturated polyether having an arithmetic mean HLB value > 9.0 calculated by the increment method of Guo, after which the clarity of the resulting addition product is visually checked, and a decision is made as to whether the process for preparing an acid-free hydrosiloxane equilibrium can be ended.

[0072] If the resulting addition product is clear, the corresponding hydrosiloxane is suitable for further processing, for example into a paint additive, and the process for preparing an acid-free hydrosiloxane equilibrium can be ended.

[0073] Preferably, in order to end the process for preparing an acid-free hydrosiloxane equilibrium, the contact of the reaction mixture with the macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups is interrupted, in particular prevented.

[0074] Conversely, if the resulting addition product is turbid, the process for preparing an acid-free hydrosiloxane equilibrium can be continued, for example, preferably until a clear addition product is obtained in the above-mentioned procedure.

[0075] The visual assessment itself can be done directly by simply observing the sample at T = 25°C. This can be reliably carried out, for example, by simple measures, for example in a preparation laboratory. An exemplary method of visual assessment can be, for example, as follows: The addition product to be assessed, i.e. the polyether siloxane, is introduced into a flat-bottomed transparent glass sample vessel, for example a beaker or, for example, a screw-cap bottle, at a temperature of 25°C with a layer thickness of about 10 mm, the latter is then placed onto a white sheet of paper printed with Arial 12-point black font, and the printed text is then read through the filled glass vessel. If the text can be read without any difficulty and without significant distortion, the addition product, i.e. the polyether siloxane, should be considered clear, and the hydrosiloxane used for the hydrosilylation has been perfectly balanced according to the invention.

[0076] The visual assessment can also preferably be performed by a group of at least 5, preferably at least 11, visually normal persons. The simple majority decision of the group can then preferably define the result. The visual assessment by a group is preferably able to compensate for the subjectivity of the perception of visually normal individuals in any desired manner.

[0077] The hydrosilylation, i.e. the hydrosilylation addition, is preferably performed in the presence of at least one noble metal catalyst, which is preferably selected from complexes and / or compounds of platinum, rhodium, osmium, ruthenium, palladium or iridium, and / or is preferably selected from the corresponding pure elements or derivatives thereof immobilized on a silica, alumina or activated carbon or similar carrier material.

[0078] The hydrosilylation can preferably be performed with the aid of at least one platinum complex, such as preferably cis-(NH3)2PtCl2(referred to as cisplatin) and / or di-μ-[chloro-dichloro(cyclohexene)platinum(II)].

[0079] The hydrosilylation can more preferably be performed with at least one zero-valent platinum complex, for example [tris(divinyltetramethyldisiloxane)dipalladium(0)] (Karstedt catalyst).

[0080] The hydrosilylation can most preferably be performed in the presence of at least one platinum(0) complex catalyst, which is dissolved in a solvent before being added to the reaction medium, and whose solution comprises at least one added unsaturated hydrocarbon having 2 to 6 carbon atoms, preferably in accordance with the teachings of EP 1520870 A1.

[0081] The amount of catalyst, based on the total reaction mixture, is preferably such that the total concentration of noble metal, preferably platinum, is 1 to 100 ppmw (parts per million by weight), preferably 2 to 10 ppmw.

[0082] It is apparent to the person skilled in the art that the minimum noble metal concentration, preferably platinum concentration, is preferably selected such that it allows a reliable, fast SiC bond formation reaction without impairing the economic viability of the process due to an excessively high use of noble metal, or in turn leading to an unfavorable discoloration of the product.

[0083] The hydrosilylation can preferably be performed at temperatures between 0°C and 200°C, preferably between 50°C and 140°C.

[0084] In the hydrosilylation, the catalyst can be used in a wide temperature range. In order to avoid side reactions, the temperature range is preferably selected at a low level such that it constitutes an acceptable compromise between the desired product purity and the production performance.

[0085] As already described, at least one unsaturated polyether is used in the noble metal catalysed hydrosilylation addition.

[0086] In the context of the noble metal catalysed hydrosilylation addition, the preferably unsaturated polyethers which can be used are preferably those which correspond to formula (I):

[0087] A [-0-(CH2-CH2-0-) n -(CH2-CH(CH3)-0-) o -Z] (I)

[0088] wherein

[0089] A is an olefinically unsaturated organic group having at least two carbon atoms, preferably at least three carbon atoms, of the organic starting compound used to provide the polyether,

[0090] Z is hydrogen, methyl-, ethyl-, propyl- or butyl-,

[0091] n = 0 to 50, preferably 9 to 30, more preferably 10 to 22,

[0092] o = 0 to 50, preferably 1 to 20, more preferably 2 to 13,

[0093] with the proviso that the sum of n and o is equal to or greater than 1, and

[0094] with the proviso that the HLB value calculated according to Guo for the unsaturated polyether is > 9.0.

[0095] The index values and the specified index value ranges indicated here can preferably be regarded as averages (weighted averages) of the possible statistical distribution of the actual structures present and / or mixtures thereof. This preferably also applies to the structural formulae as such which are copied completely, for example formula (I).

[0096] The units represented by n and o can be in the form of a statistical mixture or can be present in the chain in block form. The statistical distribution can have block structures with any number of blocks and any sequence, or they can be subject to a random distribution; they can also have an alternating structure, or form a gradient along the chain; in particular, they can also form any mixture thereof, in which groups of different distributions can optionally be connected to one another.

[0097] The unsaturated polyethers can preferably be prepared by alkoxylation reactions known in the prior art. The monomers which are preferably used in the alkoxylation reactions can preferably be ethylene oxide and / or propylene oxide, and also any mixtures of these epoxides. The monomers can be used in pure form or in the form of mixtures. The interrelationship between the metering and the product structure is known to the person skilled in the art.

[0098] Particularly preferred are polyethers of formula (I) having a weight average molar mass of 76 to 6000 g / mol, preferably 100 to 4000 g / mol, more preferably 200 to 2000 g / mol.

[0099] As starting compounds for the alkoxylation reaction, it is possible to use all compounds of the formula (II)

[0100] A[-OH] (II). The compounds of the formula (II) have a hydroxyl group and A = an olefinically unsaturated organic radical (as defined above). The olefinically unsaturated organic radical has at least two carbon atoms, preferably at least three carbon atoms. In the context of the present application, starting compounds mean the substance which forms the beginning (starting point) of the polyether or alkoxylation product to be prepared, which is obtained by addition of alkylene oxides. The starting compounds are preferably selected from the group of the olefinically unsaturated alcohols. The starting compounds used, which contain the A radical, are preferably monohydroxy- olefinically unsaturated alcohols.

[0101] Particularly preferred are radicals derived from allyl alcohol, 1-hexenol, methallyl alcohol, vinyl alcohol and vinyl oxybutanol, particularly preferred are radicals derived from allyl alcohol.

[0102] In the context of the teachings according to the present application, the preferred usable unsaturated polyethers are preferably the ethylene oxide and / or propylene oxide derivatives of the mentioned unsaturated alcohols and can include, in addition to the homo- polymer structures derived exclusively from ethylene oxide (EO), also mixed EO / PO derivatives with HLB > 9.0.

[0103] Such hydrosilylation is known per se to the person skilled in the art from the prior art, for example from the book “Chemie und Technologie der Silicone” [Chemistry and Technology of the Silicones], Verlag Chemie, 1960, page 43, and for example from US 3,775,452 and EP 1 520 870 A1.

[0104] The acid-free siloxane equilibria obtainable according to the present application are preferably stable, clear and colourless liquids which preferably contain at least only a small proportion, if any, of volatile low-molecular-weight compounds.

[0105] Surprisingly, the present application enables the preparation of the siloxane equilibria according to the present application with a very great retention of SiH functionality, which is evident, for example, by comparing the SiH equivalents weighed in advance in the reactant mixture with those SiH equivalents which can be determined analytically in the siloxanes prepared by the process according to the present application.

[0106] The SiH equivalents measured are preferably consistent within the accuracy of the analysis, which can be evidence of a very great retention of the SiH functionality used.

[0107] According to the present application, preferably, the difference between the starting SiH content of the siloxane used in general, i.e. the SiH content determined by gas capacity method before equilibration, and the final SiH content, i.e. the content of silicon-bonded hydrogen which can be determined by gas capacity method after equilibration, is < 2%.

[0108] The hydrosiloxane according to the present application is acid-free, which in the context of the present application preferably corresponds to a measurable acidity of < 2 ppm, i.e. < 2 mg KOH / kg sample, preferably measured by end-point titration, wherein 30 g of the respective sample are weighed into a titration beaker to the nearest 0.1 mg, then dissolved in about 100 ml of ethanol and a 0.1 % bromophenol blue solution is added. The resulting yellow solution is titrated on a titration processor (e.g. from Metrohm) with 0.02 molar KOH ethanol solution. The color change recorded (turning dark blue) indicates the end of the titration. The consumption of potassium hydroxide ethanol solution and the starting weight can then be used to calculate the acid value.

[0109] The macroporous, crosslinked, aqueous cation exchange resin containing sulfonic acid groups used according to the present application is, after separation of the corresponding siloxane equilibrates, preferably suitable for further use as equilibration catalyst.

[0110] As described above, in the process for preparing an acid-free hydrosiloxane equilibrates according to the present application, the siloxane mixture is reacted in a rearrangement of SiOSi bonds until the acid-free hydrosiloxane equilibrates produced in this way is added to at least one unsaturated polyether by means of a noble metal catalysed hydrosilylation, resulting in a clear addition product at T = 25 °C, the arithmetic mean HLB value of the unsaturated polyether calculated by Guo's increment method being > 9.0.

[0111] The clarity of the addition product is a simple and excellent way of assessing the quality of the hydrosiloxane equilibrates, as will become apparent in the subsequent example section. Even gas chromatography, which is often used to assess the quality of siloxane equilibrates, has its limitations here, as will also become apparent in the subsequent example section.

[0112] According to the present application, a macroporous, crosslinked, aqueous cation exchange resin containing sulfonic acid groups is used. It has a water content of 6 to 16 % by weight, preferably 8 to 12 % by weight, based on the weight of the cation exchange resin. It can be preferable to add a defined amount of water to the reactant system, i.e. to the mixture comprising at least two different siloxanes collectively having dimethylhydrogensiloxy, methylhydrogensiloxy, dimethylsiloxy and preferably trimethylsiloxy groups, in order to, for example, counteract possible water consumption by the sulfonic acid cation exchange resin.

[0113] The following examples serve merely to further illustrate the present application without in any way being limiting thereto. DETAILED DESCRIPTION

[0114] Examples:

[0115] In the subsequent examples section, only the hydrosiloxane (SiH siloxane) from which the clarified polyethersiloxane according to the application is obtained is referred to as "hydrosiloxane equilibrant". All other products are referred to in the subsequent examples section as the term "hydrosiloxane".

[0116] All percentage figures are to be regarded as percentages by weight, unless explicitly stated otherwise.

[0117] The water in the sulfonic acid cation exchanger resin is determined by the Karl Fischer method according to DIN 51777, DGF E-III 10 and DGF C-III 13a.

[0118] The acid number in the hydrosiloxane equilibrant or hydrosiloxane is determined by end-point titration in the form of a double determination, in which 30 g of the respective sample is weighed into a titration beaker to the nearest 0.1 mg, then dissolved in about 100 ml of ethanol and 0.1 % bromophenol blue solution is added. The resulting yellow solution is titrated on a titration processor (from Metrohm) with 0.02 molar KOH ethanol solution. The recorded color change (to dark blue) indicates the end of the titration. The acid number is then calculated using the consumption of potassium hydroxide ethanol solution and the starting sample weight.

[0119] The inventors have shown that the use of 15 (average pore diameter 25 nm, surface area 45 m 2 / g) (Example 4) or CT 169d (average pore diameter 24.0-42.5 nm, surface area 35-50 m 2 / g) (Example 5) as cation exchanger resin, the polyethersiloxane produced as described in the subsequent section is a turbid liquid. Thus, the important parameters for describing the catalyst phase used according to the application are the specific surface area and the porosity, i.e. the average pore diameter. If these two variables are multiplied, this has the characteristic of the inverse of the density (volume: mass) and allows a clear distinction between ion exchangers which in principle work and those which are not used according to the application.

[0120] Example 1 of the application uses K 2621, which is a macroporous sulfonic acid cation exchanger resin with an average pore diameter of 65 nm, a specific surface area of 40 m 2 / g and a water loading of 11.6% by weight, and the hydrosiloxane equilibrant according to the application is obtained.

[0121] Example 2 of the application likewise uses K 2621, with the difference that the starting cation exchange resin with a water loading of 11.6 wt.-% was adjusted to a water content of 3.2 wt.-%, which is not according to the invention, by subsequent chemical drying. The use of this cation exchange resin resulted in a hydrosiloxane, which after hydrosilylation to polyether siloxane gave a hazy product, which is not according to the invention.

[0122] Even gas chromatography, which is often used to assess the quality of siloxane equilibrates, has its limitations here, as is further shown below by comparing the measured siloxane ring concentration in five hydrosiloxanes (see Examples 1 to 5); the D4, D5 and D6 concentration of the samples differs only very little, with the exception of Example 4, so that no conclusions can be drawn about the usability of the respective hydrosiloxanes.

[0123] Preparation of the cation exchange resin for SiOSi rearrangement

[0124] The sulfonic acid cation exchange resin K 2621 (Example 1), 15 (Example 4) and CT 169d (Example 5) were each placed in an open evaporation dish in a drying cabinet heated to 60°C, then transferred in still warm condition to a moisture-excluding inert container and stored.

[0125] by subsequent chemical drying, i.e. by reaction with trimethylchlorosilane according to the following reaction equation:

[0126] 2 (CH3)3SiCI + H2O -> (CH3)3Si— O— Si (CH3)3+ 2 HCI

[0127] Reaction, the initial water content of 11.6 wt.-% of the cation exchange resin used in Example 2 was adjusted to a water content of 3.2 wt.-%. For this purpose, the sulfonic acid cation exchange resin (K 2621) was contacted with trimethylchlorosilane in a flask under nitrogen inertization under stirring at 22°C for one hour on a rotary evaporator. By applying an auxiliary vacuum (oil pump vacuum 5 mbar), then the volatiles were drawn off, and the thus chemically pre-dried cation exchange resin was separated and stored likewise under moisture exclusion. K 2621) with trimethylchlorosilane was contacted under nitrogen inertization in a flask under stirring at 22°C for one hour on a rotary evaporator. By applying an auxiliary vacuum (oil pump vacuum 5 mbar), then the volatiles were drawn off, and the thus chemically pre-dried cation exchange resin was separated and stored likewise under moisture exclusion.

[0128] Example 1 (according to the invention)

[0129] ​In a 500 ml four necked round bottom flask with a precision glass stirrer, an internal thermometer and a top reflux condenser, 38.5 g of a, co-dihydrogenopolymethylsiloxane (average chain length N = 9.82 determined by gas volumetry) were formed with 37.6 g of a trimethylsiloxy terminated poly(methylhydro)siloxane (average chain length N = 42.9 determined by gas volumetry) and 173.9 g of decamethylcyclopentasiloxane (D5) under stirring to form the initial charge. The starting SiH content was determined from a weighed sample of the mixture by gas volumetry (decomposition with sodium butoxide in butanol) to be 2.790 val SiH / kg. The siloxane mixture was then contacted with 6 wt% (based on the total mass of siloxanes) of a macroporous sulfonic acid cation exchange resin K 2621, average pore diameter 65 nm, surface area 40 m 2 / g) which had been dried in a drying cabinet at 60 °C. The water content of the pre-dried resin was determined by Karl-Fischer titration to be 11.6 wt%. The reaction mixture was heated to 40 °C under nitrogen inertization for 6 hours. Thereafter, the sulfonic acid resin was removed by filtration and the equilibrated hydridosiloxane was isolated as a colorless clear liquid.

[0130] The gas volumetry performed before the start of the reaction was repeated, the final SiH content was determined by gas volumetry (decomposition with sodium butoxide in butanol) in a gas burette using a weighed aliquot of the hydridosiloxane equilibrant. Within the range of measurement accuracy, the final SiH value corresponds to the starting SiH value of 2.790 val SiH / kg.

[0131] The accompanying gas chromatographic analysis showed a siloxane ring content present in the hydridosiloxane equilibrant of: D4 = 2.0%, D5 = 1.1% and D6 = 0.32%.

[0132] The residual acidity present in the hydridosiloxane equilibrant was determined from the acid value, which gave a value of < 2 ppm.

[0133] Example 2 (not according to the invention)

[0134] Chemical pre-drying of the cation exchange resin with 3.2 wt% of water

[0135] In a 500 ml four-necked round-bottom flask with a precision glass stirrer, an internal thermometer and a top reflux condenser, 38.5 g of a, co-dihydrogenopolymethylsiloxane (average chain length N = 9.82 determined by gasometric method) were brought together with 37.6 g of a trimethylsiloxy-terminated poly(methylhydro)siloxane (average chain length N = 42.9 determined by gasometric method) and 173.9 g of decamethylcyclopentasiloxane (D5) to form an initial charge under stirring. The starting SiH content was determined to be 2.790 val SiH / kg from a weighed aliquot of the mixture by gasometric method (decomposition with sodium butoxide in butanol) on a gas burette. The siloxane mixture was then contacted with 6 wt.-% (based on the total mass of siloxanes) of a macroporous sulfonic acid cation exchange resin K 2621, average pore diameter 65 nm, surface area 40 m 2 / g) which had been chemically predried to a water content of 3.2 wt.-% (Karl-Fischer titration). The reaction mixture was heated to 40°C under nitrogen inertization for 6 hours. Thereafter, the sulfonic acid resin was removed by filtration and the hydridosiloxane was isolated as a colorless, clear liquid.

[0136] The gasometric method performed before the start of the reaction was repeated, the final SiH content being determined by gasometric method (decomposition with sodium butoxide in butanol) on a gas burette using a weighed aliquot of the hydridosiloxane. Within the range of measurement accuracy, the final SiH value corresponds to the starting SiH value of 2.790 val SiH / kg.

[0137] The concomitant gas chromatographic analysis indicated a content of siloxane ring bodies present in the hydridosiloxane of D4 = 1.9%, D5 = 1.2% and D6 = 0.31%.

[0138] The residual acidity present in the hydridosiloxane was determined from the acid number, which gave a value of < 2 ppm.

[0139] Example 3 (reference example not according to the application)

[0140] Using triflic acid as equilibration catalyst

[0141] In a 500 ml four necked round bottom flask with a precision glass stirrer, an internal thermometer and a top reflux condenser, 38.5 g of a, co-dihydrogenopolymethylsiloxane (average chain length N = 9.82 determined by gas volumetry) were formed with 37.6 g of a trimethylsiloxy terminated poly(methylhydrogen)siloxane (average chain length N = 42.9 determined by gas volumetry) and 173.9 g of decamethylcyclopentasiloxane (D5) under stirring to form an initial charge. The starting SiH content was determined to be 2.790 val SiH / kg from a weighed aliquot of this mixture by gas volumetry (decomposition with sodium butoxide in butanol) on a gas burette. The siloxane mixture was then mixed with 0.1 wt% of triflic acid (based on the total mass of siloxanes). The reaction mixture was heated to 40°C for 6 hours under nitrogen inertization. After this time, 2.0 wt% of sodium bicarbonate (based on the total mass of siloxanes) was added and the mixture was stirred for 30 minutes. The solids were then separated by filtration and the equilibrated hydridosiloxane was isolated as a colorless clear liquid.

[0142] The gas volumetry performed at the beginning of the reaction was repeated to determine the final SiH content by gas volumetry (decomposition with sodium butoxide in butanol) on a gas burette using a weighed aliquot of hydridosiloxane. The final SiH value corresponds to a starting SiH value of 2.78 val SiH / kg within the range of the measurement accuracy.

[0143] The accompanying gas chromatography analysis determined a siloxane cyclics content in the hydridosiloxane of D4 = 1.9%, D5 = 1.1% and D6 = 0.30%.

[0144] The residual acidity in the equilibrated hydridosiloxane was determined to be 9 ppm by acid value determination.

[0145] Example 4 (not the invention)

[0146] In a 500 ml four necked round bottom flask with a precision glass stirrer, an internal thermometer and a top reflux condenser, 38.5 g of a, co-dihydrogenopolymethylsiloxane (average chain length N = 9.82 determined by gas volumetry) were formed with 37.6 g of a trimethylsiloxy terminated poly(methylhydrogen)siloxane (average chain length N = 42.9 determined by gas volumetry) and 173.9 g of decamethylcyclopentasiloxane (D5) under stirring to form an initial charge. The starting SiH content was determined to be 2.790 val SiH / kg from a weighed aliquot of this mixture by gas volumetry (decomposition with sodium butoxide in butanol) on a gas burette. The siloxane mixture was then mixed with 6 wt% (based on the total mass of siloxanes) of a macroporous sulfonic acid cation exchange resin 15, average pore size 25 nm, specific surface area 45 m 2 / g) was contacted, the macroporous sulfonic acid cation exchange resin having been dried in a drying cabinet at 60°C. The water content of the pre-dried resin was determined by Karl-Fischer titration to be 10 wt.%. The reaction mixture was heated to 40°C under nitrogen inertization for 6 hours. Thereafter, the sulfonic acid resin was removed by filtration and the hydridosiloxane was isolated as a colorless, clear liquid.

[0147] The gas volumetry performed at the beginning of the reaction was repeated, the final SiH content being determined by gas volumetry (decomposition with sodium butoxide in butanol) on a weighed aliquot of hydridosiloxane in a gas burette. The final SiH value corresponds to a starting SiH value of 2.790 val SiH / kg within the range of the measurement accuracy.

[0148] The concomitant gas chromatographic analysis determined the cyclic content in the hydridosiloxane to be D4 = 3.3%, D5 = 2.3%, and D6 = 0.68%.

[0149] The residual acidity present in the hydridosiloxane was determined from the acid number, which gave a value of < 2 ppm.

[0150] Example 5 (not according to the application)

[0151] In a 500 ml four-necked round-bottom flask with precision glass stirrer, internal thermometer and overhead reflux condenser, 38.5 g of a, co-dihydropolydimethylsiloxane (average chain length N = 9.82 determined by gas volumetry) was formed into an initial charge together with 37.6 g of a trimethylsiloxy-terminated poly(methylhydro)siloxane (average chain length N = 42.9 determined by gas volumetry) and 173.9 g of decamethylcyclopentasiloxane (D5) under stirring. The starting SiH content was determined by gas volumetry (decomposition with sodium butoxide in butanol) on a weighed aliquot of the mixture on a gas burette to be 2.790 val SiH / kg. The siloxane mixture was then contacted with 6 wt.% (based on the total mass of siloxanes) of a macroporous sulfonic acid cation exchange resin (DOWEX® CT169d, average pore diameter 24.0-42.5 nm, specific surface area 35-50 m2 / g, particle size 0.3-0.6 mm) which had been dried in a drying cabinet at 60°C. The water content of the pre-dried resin was determined by Karl-Fischer titration to be 13.1 wt.%. The reaction mixture was heated to 40°C under nitrogen inertization for 6 hours. Thereafter, the sulfonic acid resin was removed by filtration and the hydridosiloxane was isolated as a colorless, clear liquid. DOWEX® CT169d, average pore diameter 24.0-42.5 nm, specific surface area 35-50 m2 / g, particle size 0.3-0.6 mm 2 / g) was contacted, the macroporous sulfonic acid cation exchange resin having been dried in a drying cabinet at 60°C. The water content of the pre-dried resin was determined by Karl-Fischer titration to be 10 wt.%. The reaction mixture was heated to 40°C under nitrogen inertization for 6 hours. Thereafter, the sulfonic acid resin was removed by filtration and the hydridosiloxane was isolated as a colorless, clear liquid.

[0152] The gas volumetry performed at the beginning of the reaction was repeated, using a weighed aliquot of the hydrosiloxane to determine the final SiH content by gas volumetry (decomposition with sodium butoxide in butanol) in a gas volumetric flask. The final SiH value was 2.70 val SiH / kg.

[0153] The accompanying gas chromatographic analysis determined the cyclic content in the hydrosiloxane to be D4 = 1.8%, D5 = 1.0%, and D6 = 0.30%.

[0154] The residual acidity present in the hydrosiloxane was determined from the acid number, which gave a value of < 2 ppm.

[0155] Conversion of the hydrosiloxane equilibrates or hydrosiloxane isolated in examples 1 to 5 to polyether siloxanes A to E

[0156] General procedure

[0157] In a 500 ml round bottom flask with a precision glass stirrer and an overhead reflux condenser, 60 g of the respective hydrosiloxane equilibrates or hydrosiloxane were formed into a stirred initial charge with, in each case, a polyether mixture consisting of 38.8 g of a hydroxy-functional poly(ethylenoxy) poly(propylenoxy) ether with a molar mass of 615 g / mol and an allyl alcohol content of 20% (HLB value according to Guo = 11.11) and 168.4 g of a hydroxy-functional poly(ethylenoxy) poly(propylenoxy) ether with a molar mass of 1144 g / mol and an allyl alcohol content of 39% (HLB value according to Guo = 11.75) at 90°C. The initially two-phase and turbid reaction mixture was then mixed with 10 ppm of platinum in the form of a powdered cis-PtCl2(NH3)2 complex. The arithmetic mean HLB value according to Guo of the polyether mixture used was 11.56.

[0158] The hydrosilylation SiC bond formation with accompanying slight exotherm gave the polyether siloxanes. All batches were reacted for 150 minutes. After this time, samples were taken from all batches for determination of the gas volumetry SiH conversion (decomposition with sodium butoxide in butanol) in a gas volumetric flask. All batches reached quantitative SiH conversion.

[0159] At the reaction temperature, the batches of hydrosiloxane equilibrates from example 1 and example 3 (polyether siloxanes A and C) reached their respective points of clarity after only 45 minutes (polyether siloxane A) and 50 minutes (polyether siloxane C). In contrast, the batch using the hydrosiloxane from non-inventive example 2 (polyether siloxane B) remained turbid even after a reaction time of 150 minutes.

[0160] The batches of hydrosiloxane (polyether siloxanes D and E) from examples 4 and 5 likewise remained turbid at the reaction temperature even after a reaction time of 150 minutes.

[0161] The term "clear point"

[0162] Due to the incompatibility of the reactants, the reaction of SiH siloxane containing hydrosiloxane equilibrates or hydrosiloxane with unsaturated polyether to form a polyether siloxane (hydrosilylation) starts in two phases.

[0163] The increase in product concentration during the reaction is accompanied by a decrease in the concentration of the incompatible reactants, while the silicone polyether copolymer acts as a surfactant, which promotes the dispersion of the remaining droplets of incompatible reactants, in particular SiH siloxane and partially converted SiH siloxane, in the polyether matrix at the phase interface. The clear point, which can be observed in the formation of SiC bonds in silicone polyethers at the reaction temperature, is an indicator and result of this increased phase dispersion that takes place in the reaction system. At the clear point, the diameter of the individual droplets of the incompatible dispersed phase has fallen below the wavelength of visible light, and the previously turbid reaction matrix appears as a uniform, clear phase.

[0164] At 25°C, samples of the polyether siloxanes A to E to be evaluated were each introduced into a flat-bottomed glass sample vessel in a layer thickness of about 10 mm, and the vessels were then placed onto white paper printed with Arial 12-point black font, and in each case the printed text was then read through the filled glass vessel. If the text can be read without any difficulty and without significant distortion, the polyether siloxane is considered to be clear, and thus the hydrosiloxane used for hydrosilylation has been perfectly equilibrated according to the application.

[0165] Visual assessment of the polyether siloxanes A to E

[0166]

Claims

1. A method for preparing an acid-free hydrosiloxane equilibrium with the following average structural formula: in 3≤x≤100, preferably 30≤x≤80. 1≤y≤30, 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 More preferably, x + y + 2 ≥ 13. Its features are, A mixture comprising at least two different siloxanes collectively having dimethylsiloxy, methylsiloxy, dimethylsiloxy, and preferably trimethylsiloxy. The mixture is contacted with a macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups and reacted via SiOSi bond rearrangement until the acid-free hydrosiloxane equilibrium produced in this manner is added to at least one unsaturated polyether via noble metal-catalyzed hydrosilylation, yielding an addition product clarified at T = 25°C, wherein the unsaturated polyether has an arithmetic mean HLB value > 9.0 calculated by Guo's incremental method. The rearrangement of the SiOSi bonds is carried out in a temperature range of 10 to 50°C. The condition is that the macroporous cross-linked aqueous cation exchange resin containing sulfonic acid groups is characterized in that the product of its specific surface area and its average pore size, P, is P≥2.2×10⁻⁶. -3 m 3 / kg and specific surface area A is ≥35m² 2 / g, and additionally, based on the weight of the cation exchange resin, its water content is 6 to 16% by weight.

2. The method according to claim 1, characterized in that, The rearrangement of the SiOSi keys is carried out in a temperature range of 30°C to 40°C.

3. The method according to any one of claims 1 and 2, characterized in that, The rearrangement of the SiOSi keys takes place over a period of 4 to 10 hours, preferably 5 to 8 hours.

4. The method according to any one of claims 1 to 3, characterized in that, During the preparation of the acid-free hydrosiloxane balance, a hydrosiloxane sample to be evaluated is removed from the reaction mixture and reacted with at least one unsaturated polyether under noble metal-catalyzed hydrosilanization conditions. After visually inspecting the clarity of the resulting addition product, a decision is made as to whether the preparation of the acid-free hydrosiloxane balance can be terminated, wherein the unsaturated polyether has an arithmetic mean HLB value > 9.0 calculated by Guo's incremental method.

5. The method according to any one of claims 1 to 4, characterized in that, The method for preparing the acid-free hydrosiloxane balance is terminated by stopping the contact between the reaction mixture and the macroporous cross-linked aqueous cation exchange resin containing sulfonic acid groups.

6. The method according to any one of claims 1 to 5, characterized in that, The at least one unsaturated polyether satisfies formula (I): A[-O-(CH2-CH2-O-) n -(CH2-CH(CH3)-O-) o -Z](I) in A is an olefinic unsaturated organic group having at least two carbon atoms, preferably at least three carbon atoms, used to provide the organic starting compound for the polyether. Z is hydrogen, methyl-, ethyl-, propyl-, or butyl-. n = 0 to 50, preferably 9 to 30, more preferably 10 to 22 o = 0 to 50, preferably 1 to 20, more preferably 2 to 13 The condition is that the sum of n and o is not less than 1, and the HLB value calculated by Guo's incremental method is > 9.

0.

7. The method according to any one of claims 1 to 6, characterized in that, Based on the weight of the cation exchange resin, the macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups has a water content of 6 to 16% by weight, preferably 8 to 12% by weight.

8. The method according to any one of claims 1 to 7, characterized in that, The macroporous cross-linked aqueous cation exchange resin containing sulfonic acid groups is characterized in that the product of its specific surface area and its average pore size, P, is P≥2.3×10⁻⁶. -3 m 3 / kg, preferably ≥2.4×10 -3 m 3 / kg.

9. The method according to any one of claims 1 to 8, characterized in that, The macroporous crosslinked aqueous cation exchange resin containing sulfonic acid groups has an average pore size of at least 65 nm.

10. The method according to any one of claims 1 to 9, characterized in that, The mixture comprising at least two different siloxanes collectively having dimethylhydrosiloxy, methylhydrosiloxy, dimethylsiloxy, and preferably trimethylsiloxy comprises at least one α,ω-dihydropolydimethylsiloxane and at least one poly(methylhydrosiloxane), preferably at least one poly(methylhydrosiloxane) capped with trimethylsiloxy.

11. The method according to claim 10, characterized in that, The mixture further contains at least one cyclic siloxane, preferably selected from octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecylcyclohexasiloxane (D6).

12. The method according to any one of claims 1 to 11, characterized in that, The difference between the initial SiH content of the siloxane used in general, i.e. the SiH content that can be determined by gas volumetric method before equilibrium, and the final SiH content, i.e. the content of silicon-bonded hydrogen that can be determined by gas volumetric method after equilibrium, is ≤2%.

13. The method according to any one of claims 1 to 12, characterized in that, The acid-free hydrosiloxane equilibrium has a measurable acidity of ≤2ppm KOH / kg, preferably determined by endpoint titration using potassium hydroxide ethanol solution and bromophenol blue indicator.

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