Mixtures of D / T-ring-branched siloxanes and their conversion products

Abstract

The present invention provides a mixture of D / T-type cyclic branched siloxanes and their conversion products. The present invention discloses a mixture of cyclic branched siloxanes having only D and T units and no functional groups, provided that, as determined by 29 Si NMR spectroscopy, the cumulative proportion of D and T units having Si-alkoxy and / or SiOH groups present in the siloxane matrix is ≤2 mol%, and the branched organically modified siloxanes obtainable therefrom.

Description

Technical Field

[0001] The present invention relates to a process for preparing a mixture of D / T-type cyclic branched siloxanes, the mixture of D / T-type cyclic branched siloxanes per se, and a process for processing these siloxanes into functionalized branched siloxanes and / or branched siloxanes. Background Art

[0002] Reference-W.Noll, Chemie und Technologie der Silicone [Chemistry and Technology of the Silicones], Verlag Chemie GmbH, Weinheim (1960), page 2ff. is cited herein, which relates to the M, D, T, Q nomenclature used herein to describe the structural units of organopolysiloxanes.

[0003] In the preparation of organically modified siloxanes, especially branched functionalized siloxanes, a frequent difficulty is that competitive processes occurring simultaneously in the reaction matrix can have an adverse effect on the quality of the target product.

[0004] Among these competitive processes are condensation and equilibration, which need to be considered separately according to the synthesis problem. A major challenge is the uniform distribution of the branching sites along the siloxane chain, corresponding to avoiding regions of the T structure. As can be deduced from the literature, it is particularly difficult to break a uniform siloxane chain composed of T units under acid catalysis, and thus the effect cannot be achieved in the presence of sensitive functional groups. Regarding the reaction characteristics of M, D, and T units, refer to M.A. Brook, “Silicon in Organic, Organometallic and Polymer Chemistry”, John Wiley & Sons, Inc., New York (2000), p. 264ff.

[0005] Especially in the preparation of branched siloxanes having reactive SiH groups, a considerable effort is always required to reconcile the need for a statistically as uniform as possible distribution of the siloxane units and the need to retain a large amount of the useful silicon-bonded hydrogen.

[0006] According to the prior art, polyorganosiloxanes are prepared by hydrolysis and condensation of methylchlorohydrosilanes having mixed substituents. The direct hydrolysis and condensation of hydrosilanes such as dimethylchlorosilane or methyldichlorosilane is described, for example, in US 2,758,124. In this case, the siloxane phase separated during hydrolysis is separated from the aqueous phase containing hydrochloric acid. Since this process is prone to gelation of the hydrosiloxanes, DE 1 125 180 describes an improved process using an organic auxiliary phase, in which the formed hydrosiloxane is present as a separated phase dissolved in an organic solvent and is resistant to gelation after separation from the acidic aqueous phase and distillation of the solvent. EP 0 967 236 describes another process improvement for minimizing solvent input, the teachings of which include first using only a small amount of water in the hydrolysis and condensation of organochlorosilanes, so that hydrogen chloride is removed in gaseous form in the first step and can then be sent directly as a valuable material to further end uses.

[0007] Branched organically modified polysiloxanes can be described by multiple structures. Generally, a distinction must be made between branching or crosslinking introduced by organic substituents and branching or crosslinking in the polysiloxane chain. Organic crosslinking agents for forming a siloxane backbone containing SiH groups are, for example, α,ω-unsaturated dienes, divinyl compounds or diallyl compounds, as described in US 6,730,749 or EP 0 381 318. This crosslinking by platinum-catalyzed hydrosilylation downstream of the equilibrium refers to an additional process step in which both intramolecular and intermolecular bonding occur. In addition, the product properties are greatly influenced by the different reactivities of low molecular weight organic bifunctional compounds that tend to form peroxides.

[0008] The multiple crosslinking of the silicone blocks of organically modified polysiloxanes with organic block copolymers is affected in various ways. EP 0 675 151 describes the preparation of polyethersiloxanes by hydrosilylation of hydrosiloxanes with allyl polyethers having insufficient hydroxy functionality, in which, by adding sodium methoxide, the unreacted SiH functional groups are linked to the hydroxy groups of the polyether substituents via SiOC bonds. The increase in molar mass results in a wide range of dispersions in product properties such as viscosity. US 4,631,208 describes a similar method for forming a branched system, in which hydroxy-functional polyethersiloxanes are crosslinked by trialkoxysilanes. Both methods result in intermolecular crosslinking of the polyethersiloxanes, in which not only is it difficult to control the increase in molar mass, but there is also an unpredictable increase in viscosity associated therewith. Using the above methods, instead of branching within the siloxane moiety with a constant molar mass, crosslinking of macromolecular multi-block copolymers is formed.

[0009] Therefore, branching within the siloxane chain must be carried out during the preparation of the hydrosiloxane to avoid the said defects of such crosslinking. Branching within the siloxane chain requires the synthesis and incorporation of trifunctional silanes, such as trichlorosilane or trialkoxysilane.

[0010] As is known to those skilled in the art, the rate of hydrolysis of organochlorosilanes increases in the following order (C. Eaborn, Organosilicon Compounds, Butterworths Scientific Publications, London 1960, p. 179): SiCl 4 > RSiCl 3 >>R 2 SiCl 2 > R 3 SiCl.

[0011] Therefore, compared with the slower hydrolysis and condensation reactions of difunctional and monofunctional organochlorosilanes, there is a tendency for the formation of highly crosslinked gels to increase in the hydrolysis and condensation reactions of trichlorosilane. Therefore, the processes established for the hydrolysis and condensation of dichloro- and monochlorosilanes do not directly apply to trichlorosilane; instead, an indirect route via a multi-step process is required.

[0012] Based on this finding, according to the prior art, it is also necessary to prepare a single-branched hydrosiloxane in a two-step process by incorporating no more than one trifunctional monomer in each siloxane chain. For example, as taught in DE 37 16 372, in the first step, a trifunctional low molecular weight hydrosiloxane is prepared by the hydrolysis and condensation of 1,1,3,3-tetramethyldisiloxane and methyltriethoxysilane. Only in the second step is it possible to equilibrate with cyclic siloxanes and obtain a higher molar mass, as explained in DE 10 2005 004676. For further transformation - and thus only in the third step - the single-branched hydrosiloxane thus prepared can be provided by a method known per se of functionalizing the SiH group-containing siloxane compound with an organic substituent.

[0013] For the synthesis of multiply branched hydrosiloxanes, which are defined as containing more than one trifunctional monomer in each siloxane chain, there are similar two-step syntheses in the prior art. In principle, starting from a hydrosiloxane, the SiH functional group can be dehydrogenated and converted into a silanol by adding water and a noble metal catalyst, which in turn can then be condensed with the hydrosiloxane. Such steps are described in US 6,790,451 and EP 1 717 260. In addition to the cost of the noble metal catalyst, the storage stability of silanols is poor and they tend to self-condense, which makes it difficult to achieve a reproducible and controllable process scheme.

[0014] Another alternative described in US 6,790,451 is to prepare a copolymer, also known as an MT polymer, from trichloromethylsilane or trialkoxymethylsilane and hexamethyldisiloxane or trimethylchlorosilane, which is then equilibriated with a polydimethyl(methylhydrogen)siloxane copolymer in a second step. The preparation of such an MT polymer requires the use of strong bases or strong acids, and in some cases high reaction temperatures, which results in the production of highly viscous prepolymers, making their neutralization very difficult and thus severely limiting the processing into a final product of constant composition and quality.

[0015] According to EP 0 675 151, first, the hydrolysis and condensation of a SiH-free branched siloxane polymer is carried out in xylene, and the final closing of the precondensate is carried out using a large excess of hexamethyldisiloxane. In a second step, equilibration is carried out using a methylhydrogenpolysiloxane to obtain a branched hydrosiloxane (preparation method 6, as above). As an alternative, the teaching of EP 0 675 151 relates to the preparation process of a non-SiH-functional branched siloxane, which only includes the partial condensation of methyltrichlorosilane used (preparation method 7, ibid.). However, neither of these two strategies meets the need for a widely applicable preparation method for branched siloxanes.

[0016] WO 2009065644 (A1) teaches a process for preparing a branched SiH-functional siloxane by reacting a mixture in the presence of water and at least one acidic catalyst, said mixture comprising: a) one or more SiH-functional siloxanes, b) one or more siloxanes free of SiH functional groups, and c) one or more trialkoxysilanes, wherein the reaction is carried out in one process step. In its disclosure, the technical limitations of this process become more apparent when converting the SiH functional groups introduced into the system. This indicates that at least two acidic catalysts are required for sensitive SiH-functional branched siloxane structures (trifluoromethanesulfonic acid vs. trifluoromethanesulfonic acid and a sulfuric acid ion exchange resin, ibid., Examples 5 and 6), making this process very inconvenient and costly in its industrial implementation.

[0017] It has been speculated in the literature that siloxanes consisting only of D and T units may exist. As described by W. Noll in Chemie und Technologie der Silicone, Weinheim (1960), pages 181 - 182, D. W. Scott (J. Am. Chem. Soc. 68, 356, 1946) first suggested that bicyclic compounds of siloxanes containing D and T units could be obtained by very dilute co-hydrolysis of dimethyldichlorosilane and methyltrichlorosilane followed by thermal rearrangement. At bottom temperatures of 350 - 600 °C, no more than 1% of the isomers could be isolated from the viscous co-hydrolyzate and they were then described with a high degree of uncertainty by the freezing point method and elemental analysis. Scott deduced that his compound with a D - T structure contained T structural units that were directly joined to each other without passing through D units. Scott's interpretation of the results was based on the premise that all SiC bonds in the co-hydrolysis product could withstand the severe heat treatment he chose.

[0018] Makarova et al. (Polyhedron Vol. 2, No. 4, 257 - 260 (1983)) prepared 10 kinds of oligomeric methylsiloxanes with cyclic and linear segments by the method of controlled low-temperature condensation of siloxanes containing SiOH and SiCl groups in the presence of an organic amine (such as triethylamine or aniline) in a solvent of benzene or diethyl ether, separating the precipitated amine hydrochloride, washing and then fractionating the crude reaction product. Subsequently, the bicyclic methylsiloxanes were pyrolyzed at a temperature of 400 - 600 °C and then the pyrolysis products were characterized by gas chromatography. The low molecular weight compounds used in the course of this study, such as hydroxynonamethylcyclopentasiloxane, hydroxyheptamethylcyclotetrasiloxane, dihydroxytetramethyldisiloxane, were considered special species of purely academic interest from the perspective of silicone chemistry implemented on an industrial scale.

[0019] More particularly, the D / T type pure chain siloxane compounds defined by molar mass synthesized by this route are not suitable for producing organically modified siloxanes used in demanding industrial applications, such as in PU foam stabilization or in defoaming of plastic products, etc. The characteristics of the active components effectively dealing with such application fields always include a wide oligomer distribution of high, medium and low molar masses, because the oligomers therein, depending on their molar mass and diffusion characteristics, generally estimate to have different surfactant tasks in different time windows of their respective processes. However, especially in the case of branched organically modified siloxanes, due to the reaction characteristics of the M, D and T units discussed at the beginning, a statistically as good as possible oligomer distribution and a uniform distribution of siloxane units in a single molecule can only be achieved if the D / T type starting materials used conform to the distribution function. This is especially true when the organic modification is affected by intermediates with SiH groups.

[0020] Recognizing this prior art, there is currently no obvious practical solution for preparing branched organically modified siloxanes. SUMMARY OF THE INVENTION

[0021] It has now surprisingly been found that the above problems can be solved by implementing a preparation process for obtaining branched organically modified siloxanes by the following method.

[0022] In a first step, a mixture of cyclic branched siloxanes having only D and T units and substantially no functional groups is prepared, wherein a trialkoxysilane in a solvent reacts with a siloxane cyclic and / or, preferably or, α,ω-dihydroxypolydimethylsiloxane in the presence of added water and at least one acidic catalyst, especially with the additional condition that the respective cumulative proportions of D and T units, Si-alkoxy groups, and SiOH groups in the siloxane matrix do not exceed 2 mol% (determined by 29 Si NMR spectroscopy).

[0023] In a second step, the cyclic branched siloxanes are subjected to an acidic equilibration with silanes and / or siloxanes, especially functional silanes and / or siloxanes.

[0024] This gives rise to the following items of the subject matter of the present invention.

[0025] The present invention provides a mixture of cyclic branched siloxanes containing only D and T units and no functional groups, provided that the cumulative proportion of D and T units containing Si-alkoxy and / or SiOH groups present in the siloxane matrix is ≤ 2 mol% (determined by 29 Si NMR spectroscopy) and containing no other functional groups.

[0026] The present invention further provides a method for preparing a mixture of cyclic branched siloxanes containing only D and T units and substantially no functional groups, especially a mixture of cyclic branched siloxanes containing only D and T units, provided that the cumulative proportion of D and T units containing Si-alkoxy and / or SiOH groups in the siloxane matrix is ≤ 2 mol% (determined by 29 Si NMR spectroscopy) and containing no other functional groups, wherein a trialkoxysilane in a solvent reacts with a siloxane cyclic and / or, preferably or, α,ω-dihydroxypolydimethylsiloxane in the presence of added water and at least one acidic catalyst.

[0027] The present invention further provides a method for preparing a branched organo-modified siloxane, wherein in a first step, a cyclic branched siloxane is provided, preferably a mixture of cyclic branched siloxanes containing only D and T units and no functional groups, provided that the cumulative proportion of D and T units containing Si-alkoxy and / or SiOH groups in the siloxane matrix is ≤2 mol% (determined by 29 Si NMR spectroscopy), and containing no other functional groups

[0028] In a second step, the cyclic branched siloxane is equilibrated with silanes and / or siloxanes under acidic conditions.

[0029] The present invention and its subject matter will be described in more detail below.

[0030] In the cyclic branched siloxane mixture of the present invention having only D and T units, in a preferred embodiment of the present invention, the ratio of D units to T units is 10:1 - 3:1, preferably 6:1 - 4:1.

[0031] In another preferred embodiment of the present invention, the molar mass ratio M w / M n is in the range of 2 < M w / M n < 50. These parameters can be determined by gel permeation chromatography (GPC) on a toluene solution of the siloxane, such that by using a refractive index detector and by comparison with polystyrene standards, it is possible to determine its average molar mass M w and its molar mass distribution M w / M n .

[0032] When the branched T units in the above cyclic branched siloxane mixture containing only D and T units are derived from alkyltrialkoxysilanes and / or, preferably or, phenyltrialkoxysilanes, this is another preferred embodiment of the present invention.

[0033] When the branched T units are derived from methyltriethoxysilane, this is also a preferred embodiment of the present invention.

[0034] The above mixture according to the present invention can in particular be obtained by a method according to the present invention for preparing a mixture of cyclic branched siloxanes containing only D and T units, wherein a trialkoxysilane in a solvent reacts with a siloxane ring and / or, preferably or, α,ω-dihydroxypolydimethylsiloxane in the presence of added water and at least one acidic catalyst. This includes hydrolysis and condensation under acid equilibration conditions.

[0035] The following is a description of a more particular method, which is preferred but is merely an example and thus does not limit the subject matter of the present invention.

[0036] Preferably, first, a trialkoxysilane and a siloxane cyclic compound can be added to a suitable solvent (such as toluene or cyclohexane), and then a catalytic amount of an equilibrium acid (for example, trifluoromethanesulfonic acid at 0.2 m% based on the mass of the reactants excluding the solvent) is added.

[0037] The initial equilibration is carried out, for example, for 4 hours in the toluene phase at 60 °C, and then a water / ethanol mixture (100% excess of H 2 O based on the groups to be condensed) is added, and the reaction mixture is heated, for example, to the reflux temperature (about 80 °C) for 4 hours. The reflux condenser is preferably replaced by a water separator, and the reaction mixture is heated to about 100 °C within 1 hour. During this process, the bottom temperature rises constantly, and the volatiles are continuously discharged. When the excess water is completely separated out, the reaction mixture becomes clear.

[0038] After cooling to about 70 °C, for example, a second portion of the water / ethanol mixture (about 1 / 3 of the amount used in the initial equilibration step) is added, and the reaction mixture is heated to the reflux temperature (about 80 °C) for 1 hour. The reflux condenser is replaced by a water separator, and the reaction mixture is heated to about 100 °C. The bottom temperature rises, and the volatiles are continuously discharged. At the point when the excess water is completely separated out, the reaction mixture becomes clear.

[0039] The reaction mixture is cooled to about 60 °C, and for neutralization, 4 m% of NaHCO 3 is added with stirring. After about 30 minutes, the solids in the reaction mixture are removed by filtration. The solvent (toluene) is distilled off under an auxiliary vacuum of 70 °C and 1 mbar.

[0040] What is obtained is a clear, colorless, low-viscosity liquid, and the corresponding 29 Si NMR spectrum shows the main presence of D and T units. The ratio of D and T units is preferably 10:1 - 3:1, more preferably 6:1 - 4:1. Through spectral analysis, Si-alkoxy and SiOH groups can be found, and their signal intensity is at most about 0.5% - 1%, if any. The determinable cumulative ratio of D and T units containing Si-alkoxy and SiOH groups in the siloxane matrix is ≤2 mol% in any case.

[0041] The above exemplary method has achieved excellent results, and the objectives achieved according to the present invention can be seen.

[0042] In the process according to the invention, if the solvent used is a water-immiscible silicon-free inert solvent, preferably selected from isomeric xylenes, alkyl aromatic compounds (such as preferably toluene) and / or cycloaliphatic compounds (such as preferably cyclohexane), or ethyl carbonate, the preferred mass ratio of the solvent to the siloxane is 1:1 - 5:1, which is a preferred embodiment of the present invention.

[0043] Depending on the desired D / T ratio, the amount of the solvent is preferably such that the viscosity can be effectively handled during the reaction. Preferably, the mass ratio of the solvent to the siloxane is selected to be 1:1 - 5:1. In particular, in the case where the D / T ratio is less than 5:1, the amount of the unadjusted solvent will cause the viscosity to rise to gelation. On the other hand, once the solvent has been selected, some preliminary tests (see Example 4 (gelation system) and Example 5 (manageable system)) can be used to determine the optimal mass ratio of the solvent to the siloxane.

[0044] In a preferred embodiment of the present invention, the acidic catalyst used in the method according to the invention can be:

[0045] (a) p-toluenesulfonic acid, trifluoromethanesulfonic acid, trichloroacetic acid, sulfuric acid, perchloric acid, phosphoric acid and / or hexafluorophosphoric acid, in each case based on the silicon-containing component of the reaction matrix, the preferred amount being 0.1 - 2.0 wt%, and the more preferred amount being 0.15 - 1.0 wt%,

[0046] or

[0047] (b) highly crosslinked ion exchange resins containing sulfonic acid groups, in each case based on the silicon-containing component of the reaction matrix, the preferred amount being 1.0 - 10.0 wt%, and the more preferred amount being 2.0 - 6.0 wt%.

[0048] Suitable acidic catalysts will be described in detail below.

[0049] If the reaction is carried out in the temperature range of 10 - 150 °C, preferably 20 - 120 °C, especially 40 - 110 °C, this is a further preferred embodiment of the present invention.

[0050] If at least 100% excess H 2 O is used based on the groups to be condensed, this is also a further preferred embodiment of the present invention.

[0051] If the reaction includes a preliminary equilibration step at T > 40 °C, followed by a condensation initiated by the addition of water at T > 60 °C, where the water is added in one portion, several portions or continuously, this is still a further preferred embodiment of the present invention.

[0052] As described in detail above, the present invention further provides a method for preparing a branched organically modified siloxane, wherein in a first step, a cyclic branched siloxane is provided, preferably a mixture of cyclic branched siloxanes containing only D and T units and no functional groups, provided that the cumulative proportion of D and T units containing Si-alkoxy and / or SiOH groups present in the siloxane matrix does not exceed 2 mol% (determined by 29 Si NMR spectroscopy), and contains no functional groups other than this, and

[0053] in a second step, the cyclic branched siloxane is subjected to acid equilibration with a silane and / or a siloxane, preferably a functional silane and / or a siloxane.

[0054] Functional silanes and / or siloxanes refer to those compounds containing one and / or more silicon atoms that can be incorporated into the copolymer (corresponding cyclic branched siloxane) by acid equilibration. More particularly, these acid-equilibratable silanes or siloxanes also have hydroxyl, alkoxy, and chlorine substituents, as well as hydrogen, alkyl, or aryl, or vinyl substituents. Functional silanes or siloxanes having acidic moieties such as toluenesulfonate, trifluoromethanesulfonate, and sulfate groups are also suitable here.

[0055] As a special case, branched silicone oils can be obtained by acid co-equilibration of the D / T-type cyclic branched siloxanes obtained in the first step with hexamethyldisiloxane and / or, preferably or, polydimethylsiloxane. A corresponding method for preparing a branched silicone oil according to the present invention corresponds to another part of the subject matter of the present invention, wherein in a first step, a mixture of cyclic branched siloxanes as described above is provided, and in a second step, the mixture of cyclic branched siloxanes is reacted with polydimethylsiloxane or hexamethyldisiloxane.

[0056] However, according to the present invention, it is more preferred to provide a branched organically modified siloxane. In order to obtain this final organically modified siloxane structure, acid equilibration with a functional silane and / or a siloxane is carried out as the second step.

[0057] Acidic catalysts suitable for both steps in the method according to the present invention are strong acids (equilibration acids) known from the prior art for siloxanes, namely mineral acids (such as sulfuric acid, and can also be sulfonic acids), fluoroalkylsulfonic acids (such as trifluoromethanesulfonic acid), acidic alumina, or acidic ion exchange resins (such as products sold under the trade names or and ).

[0058] In the process according to the invention, natural ion exchangers (such as zeolites, montmorillonites, attapulgites, bentonites and other aluminosilicates) or synthetic ion exchangers can be used. The latter are preferably solids (usually in the form of granules) having a three-dimensional, water-insoluble high molecular weight matrix based on a phenolic resin or a copolymer of styrene-divinylbenzene, into which a large number of differently acidic "anchoring groups" are incorporated.

[0059] Acidic ion exchangers advantageously used in the present invention include those described in EP 1 439 200.

[0060] Preferably, a sulfonic acid catalyst is used, and trifluoromethanesulfonic acid is particularly preferably used.

[0061] In the first step of the process according to the invention (corresponding to the preparation of the above-mentioned mixture of cyclic branched siloxanes), any trialkoxysilane can theoretically be used. In the trialkoxysilanes used, the alkoxy groups are all the same or all different, or partially the same. The trialkoxysilanes used can in particular be triethoxysilane (preferably methyltriethoxysilane), alkyltriethoxysilanes (such as n-propyltriethoxysilane, isobutyltriethoxysilane, pentyltriethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, hexadecyltriethoxysilane, n-octadecyltriethoxysilane), halogenated or pseudohalogenated alkyltrialkoxysilanes, in particular alkyltriethoxysilanes (such as 3-chloropropyltriethoxysilane, tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane, nonafluoro-1,1,2,2-tetrahydrohexyltriethoxysilane, 3-cyanopropyltriethoxysilane), trialkoxysilanes, in particular triethoxysilanes containing functional groups (such as 3-methacryloxypropyltriethoxysilane, 3-mercaptopropyltriethoxysilane, 5-(bicycloheptenyl)triethoxysilane, phenyltriethoxysilane, (p-chloromethyl)phenyltriethoxysilane, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole or dihydro-3-[3-(triethoxysilyl)propyl]furan-2,5-dione). It is advantageous to use organofunctional trialkoxysilanes as branching units (included in the equilibrium).

[0062] As described in further detail, suitable compounds for functionalizing these cyclic branched siloxanes in the second step are theoretically all acid-balanced silicon compounds, preferably silanes and / or siloxanes suitable for acid balancing.

[0063] The silanes and / or siloxanes used can be any acid-balanced silicon compounds. The silanes used are especially diethoxydimethylsilane, trimethylalkoxysilane, and dimethyldichlorosilane. The siloxanes used are especially tetramethyldisiloxane, α,ω-dihydro-polydimethylsiloxane, poly(methylhydrogen)siloxane, α,ω-dialkoxy-polydimethylsiloxane, or α,ω-divinyl-polydimethylsiloxane.

[0064] A key advantage of the preparation method according to the invention is that the synthesis of the mixture of cyclic branched siloxanes without functional groups (the target in the first step) can be carried out under severe reaction conditions, such as at high acid concentration and high temperature, without damaging the product because there are no sensitive groups (such as SiH functional groups) in it. Therefore, the branched units (T structures) can be optimally incorporated into the molecular backbone of the siloxane oligomers, where in each case the T structures are ideally separated by D units and do not occur in a cumulative form in a domain-like manner, as 29 shown by Si NMR spectroscopy, especially in the displacement region of the T structures.

[0065] Gas chromatographic analysis shows that typically, simple siloxane rings such as D 4 (octamethylcyclotetrasiloxane), D 5 (decamethylcyclopentasiloxane), and D 6 (dodecamethylcyclohexasiloxane) appear in the equilibrium only in proportions of less than 10% by weight.

[0066] If desired for subsequent applications (e.g., in the context of VOC (VOC = volatile organic compound) analysis or anti-fogging), these siloxane rings can be removed by simple distillation and recycled.

[0067] On the other hand, compared with the temperatures up to 600 °C described in the literature, the thermal reaction conditions selected in the method of the invention can be called very mild.

[0068] In each case, based on the trialkoxysilane used, the D / T-type cyclic branched siloxanes are obtained in a practically quantitative yield.

[0069] It is obvious to those skilled in the art that the branched organically modified siloxanes obtained by the acid equilibration in the second step are suitable as starting materials for producing stabilizers for PUR foams, defoamers, coating additives, emulsifiers (especially cosmetic emulsifiers), cosmetic conditioners, degassing agents, demulsifiers, fabric finishing agents, building protection additives, polymer additives (especially anti-scratch additives), anti-fouling additives or coatings, and anti-icing coatings. Such applications form another part of the subject matter of the present invention.

[0070] Based on the functional groups added in the second step (such as SiH groups (see Example 6) or SiCl groups (see Example 10)), for all these above-mentioned applications, after selecting a suitable co-reactant, the final SiC-bonded product is obtained by hydrosilylation, or the final SiOC-bonded product is obtained by dehydrogenative SiOC bond formation or by condensation through known methods in silicon chemistry.

[0071] In the present invention 29 Si NMR samples were analyzed on a Bruker Avance III spectrometer equipped with a 287430 sample head with a gap width of 10 mm at a measurement frequency of 79.49 MHz. The samples were dissolved in CDCl 3 at 22 °C and tetramethylsilane (TMS) was used as an external standard [δ( 29 Si) = 0.0 ppm].

[0072] In the present invention, the weight-average molar mass M w and molar mass distribution M w / M n were determined by gel permeation chromatography from a toluene solution of the siloxane using an EcoSEC GPC / SEC device of TOSOH Bioscience GmbH. A 55.00 cm long Micro SDV 1000 / 10000 column was used in combination with an EcoSEC RI detector (dual-flow refractive index detection). Polystyrene standards covered a molar mass range from 162 g / mol to 2520000 g / mol. Examples

[0073] 1) Preparation of a cyclic branched siloxane with a target D / T ratio of 8:1 (present invention).

[0074] In a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 40.5 g (0.227 mol) of methyltriethoxysilane and 134.5 g (0.363 mol) of decamethylcyclopentasiloxane in 200 ml of toluene were heated to 60 °C with stirring, and 0.375 g of trifluoromethanesulfonic acid was added, and the mixture was equilibrated for 4 hours. Then 12.3 g of water and 3.1 g of ethanol were added, and the mixture was heated to the reflux temperature of about 80 °C for another 4 hours. The reflux condenser was replaced with a distillation system, and the components that volatilized up to 100 °C were distilled off within the next hour. Then the distillation system was replaced with a reflux condenser, 6.15 g of water and 1.5 g of ethanol were added to the mixture, and the mixture was boiled for another 1 hour. Then the distillation system was again replaced with a reflux condenser, and the components that volatilized up to 100 °C were removed within the next hour. The mixture was cooled to 60 °C, then 4 m% sodium bicarbonate was added, the mixture was stirred for half an hour, and then the salt was separated from the liquid phase with the help of a fluted filter. The volatiles were distilled off on a rotary evaporator at 70 °C and a pressure of <1 mbar, and a colorless mobile liquid was separated, which 29 Si NMR spectrum showed that the D / T ratio was

[0075] 7.62:1 (target: 8:1).

[0076] GPC had a broad molar mass distribution, characterized by M w = 70317 g / mol; M n : 1941 g / mol, M w / M n = 36.24.

[0077] 2) Preparation of a cyclic branched siloxane with a target D / T ratio of 6:1 (the present invention).

[0078] Similar to Example 1, in a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 52.2 g (0.293 mol) of methyltriethoxysilane and 130.3 g (0.351 mol) of decamethylcyclopentasiloxane were heated to 60 °C with stirring in 200 ml of toluene. 0.400 g of trifluoromethanesulfonic acid was added, and the mixture was equilibrated for 4 hours. Then 15.8 g of water and 4.0 g of ethanol were added, and the mixture was heated to a reflux temperature of about 80 °C for an additional 4 hours. The reflux condenser was replaced with a distillation system, and the components that volatilize up to 100 °C were distilled off within the next hour. Then the distillation system was replaced with a reflux condenser, 7.90 g of water and 2.0 g of ethanol were added to the mixture, and the mixture was boiled for another 1 hour. Then the reflux condenser was replaced with the distillation system again, and the components that volatilize up to 100 °C were removed within the next hour. The mixture was cooled to 60 °C, then 4 m% sodium bicarbonate was added, the mixture was stirred for half an hour, and then the salt was separated from the liquid phase with the help of a grooved filter. The volatiles were distilled off on a rotary evaporator at 70 °C and a pressure of <1 mbar, and a colorless mobile liquid was separated, which 29 The Si NMR spectrum shows that the D / T ratio is

[0079] 5.85:1 (target: 6:1).

[0080] 3) Preparation of a larger amount of cyclic branched siloxane with a target D / T ratio of 6:1 (the present invention).

[0081] In a 4000 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 261.0 g (1.46 mol) of methyltriethoxysilane and 652.5 g (1.76 mol) of decamethylcyclopentasiloxane were heated to 60 °C with stirring in 200 ml of toluene. 1.983 g of trifluoromethanesulfonic acid was added, and the mixture was equilibrated for 4 hours. Then 79.0 g of water and 19.75 g of ethanol were added, and the mixture was heated to a reflux temperature of about 80 °C for an additional 4 hours. The reflux condenser was replaced with a distillation system, and the components that volatilize up to 100 °C were distilled off within the next hour. Then the distillation system was replaced with a reflux condenser, 26.30 g of water and 6.6 g of ethanol were added to the mixture, and the mixture was boiled for another 1 hour. Then the reflux condenser was replaced with the distillation system again, and the components that volatilize up to 100 °C were removed within the next hour. The mixture was cooled to 60 °C, then 4 m% sodium bicarbonate was added, the mixture was stirred for half an hour, and then the salt was separated from the liquid phase with the help of a grooved filter. The volatiles were distilled off on a rotary evaporator at 70 °C and a pressure of <1 mbar, and a colorless mobile liquid was separated, the corresponding 29 The Si NMR spectrum shows that the D / T ratio is

[0082] 5.74:1 (Target: 6:1). The dynamic viscosity at 25 °C is 598 mPas. GC shows that the residual content is D 4 = 3.2%, D 5 = 3.9% and D 6 = 1.4%.

[0083] GPC has a wide molar mass distribution, characterized by M w = 91965 g / mol; M n : 2214 g / mol, M w / M n = 41.54.

[0084] 4) Preparation of a cyclic branched siloxane with a target D / T ratio of 4:1 (without adjusting the solvent amount)

[0085] Similar to Example 1, in a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 73.5 g (0.412 mol) of methyltriethoxysilane and 122.3 g (0.33 mol) of decamethylcyclopentasiloxane in 220 ml of toluene were heated to 60 °C with stirring, and 0.436 g of trifluoromethanesulfonic acid was added, and the mixture was equilibrated for 4 hours. Then 22.3 g of water and 5.6 g of ethanol were added, and the mixture was heated to a reflux temperature of about 80 °C for an additional 4 hours. The reflux condenser was replaced with a distillation system, and the components that volatilized up to 100 °C were distilled off within the next hour. Then the distillation system was replaced with a reflux condenser, 7.50 g of water and 1.9 g of ethanol were added to the mixture, and the mixture was boiled for 1 hour. Then the distillation system was replaced with a reflux condenser again. During the subsequent distillation process, the viscosity of the bottom components increased significantly, resulting in a large amount of silicone gelation and was discarded.

[0086] 5) Preparation of a cyclic branched siloxane with a target D / T ratio of 4:1 (according to the present invention, the adjusted solvent amount is 1:3).

[0087] Similar to Example 1, in a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 36.8 g (0.206 mol) of methyltriethoxysilane and 61.2 g (0.165 mol) of decamethylcyclopentasiloxane were heated to 60 °C with stirring in 330 ml of toluene. 0.218 g of trifluoromethanesulfonic acid was added, and the mixture was equilibrated for 4 hours. Then 11.2 g of water and 2.8 g of ethanol were added, and the mixture was heated to a reflux temperature of about 80 °C for an additional 4 hours. The reflux condenser was replaced with a distillation system, and the components that volatilized up to 100 °C were distilled off within the next hour. Then the distillation system was replaced with a reflux condenser, 2.70 g of water and 0.9 g of ethanol were added to the mixture, and the mixture was refluxed for 1 hour. Then the reflux condenser was replaced with the distillation system again, and the components that volatilized up to 100 °C were removed within the next hour. The mixture was cooled to 60 °C, then 4 m% sodium bicarbonate was added, the mixture was stirred for half an hour, and then the salt was separated from the liquid phase with the help of a fluted filter. The volatiles were distilled off on a rotary evaporator at 70 °C and a pressure of <1 mbar, and a colorless mobile liquid was separated, which 29 Si NMR spectrum showed that the D / T ratio was

[0088] 3.6:1 (target: 4:1).

[0089] GPC had a molar mass distribution with the following characteristics:

[0090] M w = 12344 g / mol; M n : 3245 g / mol, M w / M n = 2.63.

[0091] 6) Preparation of branched hydrosiloxanes with terminal SiH functional groups using the cyclic branched siloxane prepared in Example 1, α,ω-dihydro-polydimethylsiloxane, and decamethylcyclopentasiloxane

[0092] In a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 37.4 g of the cyclic branched siloxane prepared in Example 1, 6.3 g of α,ω-dihydro-polydimethylsiloxane (SiH value: 2.90 eq / kg), and 186.3 g of decamethylcyclopentasiloxane were heated to 40 °C for 6 hours after adding 0.25 g of trifluoromethanesulfonic acid (0.1 m% of the total mixture), then 5 g of sodium bicarbonate was added, and the mixture was stirred for another 30 minutes. The salt was separated from the equilibrium mixture with the help of a filter press (Seitz K 300 filter sheet).

[0093] A colorless branched hydrosiloxane with dimethylhydroxysilyloxy functional groups at the terminals (SiH value: 0.30 eq / kg) was obtained. Corresponding29 The Si NMR spectrum confirmed the target structure.

[0094] 7) Preparation of branched siloxanes with terminal ethoxy functional groups (the present invention)

[0095] In a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 114.8 g of the cyclic branched siloxane prepared in Example 2, 33.9 g of dimethyldiethoxysilane, and 101.1 g of decamethylcyclopentasiloxane were heated to 60 °C for 6 hours after adding 0.25 g of trifluoromethanesulfonic acid (0.1 m% of the total mixture), then 5 g of sodium bicarbonate was added, and the mixture was stirred for another 30 minutes. The salt was separated from the equilibrium with the help of a filter press (Seitz K 300 filter disc).

[0096] Corresponding 29 The Si NMR spectrum confirmed the target structure.

[0097] 8) Preparation of branched siloxanes with terminal vinyl functional groups (the present invention)

[0098] In a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 109.2 g of the cyclic branched siloxane prepared in Example 3, 41.3 g of divinyltetramethyldisiloxane, and 99.5 g of decamethylcyclopentasiloxane were heated to 60 °C for 6 hours after adding 0.25 g of trifluoromethanesulfonic acid (0.1 m% of the total mixture), then 5 g of sodium bicarbonate was added, and the mixture was stirred for another 30 minutes. The salt was separated from the equilibrium with the help of a filter press (Seitz K 300 filter disc).

[0099] Corresponding 29 The Si NMR spectrum confirmed the branched siloxane with terminal vinyl functional groups as the target structure.

[0100] 9) Preparation of branched silicone oil (the present invention)

[0101] In a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer and a reflux condenser at the top, 111.6 g of the cyclic branched siloxane prepared in Example 3, 36.7 g of hexamethyldisiloxane, and 101.7 g of decamethylcyclopentasiloxane were heated to 60 °C for 6 hours after adding 0.25 g of trifluoromethanesulfonic acid (0.1 m% of the total mixture), then 5 g of sodium bicarbonate was added, and the mixture was stirred for another 30 minutes. The salt was separated from the equilibrium with the help of a filter press (Seitz K 300 filter disc).

[0102] Corresponding 29The Si NMR spectrum confirmed a branched non-functional silicone oil as the target structure. 10) Preparation of a branched sulfate-bridged siloxane with terminal chlorine functional groups (chlorosiloxanyl sulfate ester, the present invention)

[0103] a) Preparation of a linear chlorosiloxanyl sulfate ester precursor

[0104] In a 500 ml four-necked round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser at the top, first, 105.4 g of α,ω-dichloropolysiloxane with an average chain length N = 5.5 and 28.2 g of decamethylcyclopentasiloxane were added under stirring, and then 5.6 g of concentrated sulfuric acid was added. The mixture was placed in the reactor at 50 °C for 1 hour and then at 100 °C for 2 hours. After cooling to 20 °C, a colorless clear liquid was obtained.

[0105] b) Equilibration of the precursor obtained in a) with D / T rings

[0106] Under stirring, within 5 minutes, 110.8 g of D / T siloxane prepared according to a similar Example 2 (the D / T ratio determined by 29 Si NMR was 5.63:1) was added to the precursor obtained in a).

[0107] Under the condition of vigorously stirring the reactants, equilibration was carried out at 22 °C for 30 minutes, at 50 °C for 1 hour, and at 100 °C for 6 hours.

[0108] Under an applied auxiliary vacuum of 1 mbar, the volatile components were removed at 50 °C within 2 hours. After cooling the liquid phase, a water-clear colorless liquid with an acid value of 1.82 mmol acid / g of substance (the theoretical value was: 1.853 mmol acid / g of substance) was separated. 29 The Si NMR spectrum confirmed the expected structure.

Claims

1. Process for the preparation of a mixture of cyclic branched siloxanes having only D and T units, provided that the cumulative proportion of D and T units having Si-alkoxy and / or SiOH groups present in the siloxane matrix, determined by 29 Si NMR spectroscopy, is ≤ 2 mol%, and which contains no other functional groups It is characterized in that trialkoxysilane in a solvent is reacted with a siloxane cyclic compound and / or α,ω-dihydroxypolydimethylsiloxane in the presence of water and at least one acidic catalyst, wherein the mass ratio of the solvent to the siloxane is 1:1 - 5:1, and the reaction includes a preliminary equilibration step at a temperature T > 40 °C, followed by condensation initiated by adding water at a temperature T > 60 °C, wherein the water is added in one portion, several portions or continuously.

2. The preparation method according to claim 1, wherein, the ratio of D units to T units in the mixture of cyclic branched siloxanes having only D and T units is 10:1 - 3:

1.

3. The preparation method according to claim 1, wherein, the ratio of D units to T units in the mixture of cyclic branched siloxanes having only D and T units is 6:1 - 4:

1.

4. The preparation method according to claim 1, wherein, The molar mass ratio M of the mixture of the cyclic-branched siloxanes having only D and T units w / M n is in the range of 2 < M w / M n < 50.

5. The preparation method according to claim 1, wherein, the branched T units in the mixture of cyclic branched siloxanes having only D and T units are from alkyltrialkoxysilane and / or phenyltrialkoxysilane.

6. The preparation method according to claim 1, wherein, the branched T units in the mixture of cyclic branched siloxanes having only D and T units are from methyltriethoxysilane.

7. The method according to any one of claims 1 - 6, it is characterized in that the solvent used is a silicon-free inert solvent immiscible with water, and / or a cycloaliphatic compound and / or ethyl carbonate.

8. The method according to claim 7, wherein, the silicon-free inert solvent immiscible with water is selected from alkylaromatic compounds.

9. The method according to claim 8, wherein, the alkylaromatic compounds are selected from isomeric xylenes and toluene.

10. The method according to claim 7, wherein, the cycloaliphatic compound is cyclohexane.

11. The method according to claim 1, it is characterized in that the acidic catalyst used is: (a) p-toluenesulfonic acid, trifluoromethanesulfonic acid, trichloroacetic acid, sulfuric acid, perchloric acid, phosphoric acid and / or hexafluorophosphoric acid, or (b) a highly crosslinked ion exchange resin containing a sulfonic acid group.

12. The method according to claim 11, wherein for component (a), in each case based on the silicon-containing components of the reaction matrix, the amount is 0.1 - 2.0% by weight.

13. The method according to claim 11, wherein for component (a), in each case based on the silicon-containing components of the reaction matrix, the amount is 0.15 - 1.0% by weight.

14. The method according to claim 11, wherein for component (b), in each case based on the silicon-containing components of the reaction matrix, the amount is 1.0 - 10.0% by weight.

15. The method according to claim 11, wherein for component (b), in each case based on the silicon-containing components of the reaction matrix, the amount is 2.0 - 6.0% by weight.

16. The method according to claim 1, it is characterized in that the reaction is carried out in a temperature range of 10 - 150 °C.

17. The method according to claim 1, it is characterized in that The reaction is carried out in the temperature range of 20 - 120 °C.

18. The method according to claim 1, characterized in that the reaction is carried out in the temperature range of 40 - 110 °C.

19. The method according to claim 1, characterized in that Based on the group to be condensed, use at least 100% of H 2 O in excess.