METHOD FOR THE PREPARATION OF POLYOXYALKYLENE POLYSILOXANE BLOCK POLYMERIZATES

Description

[0001] The invention relates to a process for the preparation of SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type CB-(AB) a -C1 and to their use as components in surface-active substances, such as in PU foam stabilizers, defoamers, deaerators, emulsifiers, demulsifiers and paint and leveling additives.

[0002] The terms "siloxanes" and "polysiloxanes" are used as synonyms in the present invention.

[0003] In this case, the term "defoamer" encompasses both products and formulations that prevent foam, as well as those that destroy foam and enable deaeration. In practice, the boundaries between these product properties are fluid, so the collective term "defoamer" is used here.

[0004] In many technical processes, particularly when working in aqueous media, it is necessary to suppress or completely prevent the undesirable formation of foam during the manufacturing or processing processes, since foam or foam crowns that form during stirring and dispersing processes or in the containers during the filling process can extend production times or reduce the effective volume of the system or even prevent it from working correctly, as an overflow of the formulation from the mixing vessel cannot be avoided and a lack of color transfer is unavoidable when applying this.

[0005] This can be achieved by adding defoamers, which, even at very low concentrations starting at approximately 0.001 wt.%, are capable of preventing or destroying unwanted foaming, while simultaneously preventing surface defects after application of the systems and suppressing air inclusions in the paint. In practice, these aspects must be considered at least as much as effective defoaming.

[0006] Surface defects include undesirable properties such as pinholes, craters, loss of gloss, the orange peel effect, wrinkling, and loss of adhesion in the coating system. However, the long-term stability of the defoamer in formulations is also of great importance to the user, as products such as paints are often not used immediately, but sometimes only after extended storage. When stored under extreme climatic conditions (heat and sunlight), the effectiveness of a defoamer formulation can sometimes collapse after a short period of time.

[0007] State-of-the-art defoamers include, for example, silicone oils, native oils, paraffin and mineral oils, but also hydrophobic polyoxyalkylenes, long-chain alcohols and mixtures of these products and emulsions thereof.

[0008] Defoamers for defoaming aqueous and non-aqueous media, which contain polyoxyalkylene polysiloxane polymers as the active ingredient that significantly influences defoaming, demonstrate exceptional effectiveness and storage stability. These include foam inhibition, defoaming, very good long-term stability, and outstanding compatibility in aqueous and non-aqueous media. All of these properties are of great importance for modern coating applications.

[0009] To enhance effectiveness, so-called hydrophobic solids are often added in amounts of 0.1 to 10 wt.%. These specifically promote dewetting processes at foam lamellae and thus very effectively support foam collapse. Suitable hydrophobic solids include appropriately hydrophobized or non-hydrophobized silicas, hydrophobized or non-hydrophobized precipitated silica, metal carboxylates such as metal stearates, polyolefins, and natural or synthetic waxes such as paraffin waxes, polyolefin waxes, amide waxes, and urea or poly(ureas), as described, for example, in DE 28 29 906 A1.

[0010] By adding suitable emulsifiers or protective colloids, such defoamer formulations can also be converted into aqueous emulsions, which can be more easily incorporated into coating formulations. CN 101100515 A describes a specific emulsification process that can also be used for the emulsification of polyether polysiloxane polymers.

[0011] The use of polyoxyalkylene-polysiloxane block copolymers as defoamers is also known. For example, DE 1 012602 describes polyoxyalkylene-polysiloxane polymers having an A'-B'-A' structure, where A' denotes the polyoxyalkylene blocks and B' a polysiloxane block. These active substances belong to the so-called SiOC polyethersiloxane defoamer class.

[0012] DE 24 43 853 describes defoaming preparations which contain both linear and branched polyoxyalkylene polysiloxane block copolymers.

[0013] US Pat. No. 4,028,218 describes a process for preventing or destroying foam in aqueous solutions or dispersions, using a preparation similar to that described in DE 24 43 853. The preparation differs essentially in its additional content of organic oil, which also has a defoaming effect. Suitable organic oils are esters of alcohols and fatty acids, such as vegetable or animal oils, or mineral oils, polybutadiene oils, or polypropylene glycols.

[0014] To produce the economically important substance class of SiOC-linked polyether siloxanes, also known as silicone polyethers or polysiloxane polyether copolymers, several process variants are used according to the current state of the art.

[0015] Those skilled in the art know that these SiOC-linked polyethersiloxanes belong to a class of products that do not tend to resinify. Even though SiOC-linked polyethersiloxanes contain reactive groups, such as hydroxyl groups, they are not used for targeted crosslinking. Unlike silicone resins, they do not form films.

[0016] Traditionally, SiOC-linked polyether siloxanes are formed by the reaction of a polysiloxane with a leaving group (e.g. halogen) bonded to the silicon atom and an alcohol or polyetherol. The latter is usually obtained beforehand by alkoxylation of hydroxy-functional starting compounds such as methanol, butanol or glycol with alkylene oxides. Chlorine as a leaving group on the silicon atom is particularly well-known and widely used as a starting compound for this type of reaction. However, chlorosiloxanes and chloropolysiloxanes are difficult to handle because they are extremely reactive. Their use is also associated with the disadvantage that the hydrogen chloride formed during the reaction requires corrosion-resistant equipment and leads to both technical and ecological challenges. Furthermore, in the presence of chloropolysiloxanes and alcohols orPolyetherols produce organic chlorine compounds that are undesirable for toxicological reasons, so that there was a need to suppress and destroy them during the manufacturing process. As is known to those skilled in the art, it is also necessary to achieve and ensure quantitative conversion when reacting a chlorosiloxane with an alcohol or polyetherols, so that the OH-functional component often has to be used in a stoichiometric excess relative to the chlorine leaving group of the polysiloxane component. In practice, the use of an excess of polyether means that the polyethersiloxanes thus produced inevitably contain larger amounts of unreacted excess polyethers, which reduce the concentration of the active polyethersiloxane component and impair the performance properties of the polyethersiloxanes.In the process described above, HCl scavengers often have to be used additionally to achieve the required quantitative conversion. The use of HCl scavengers results in large amounts of salt, which are difficult to remove on an industrial scale.

[0017] Defoamers for defoaming aqueous and non-aqueous media, which contain linear polyoxyalkylene polysiloxane block copolymers as the active ingredient that significantly influences defoaming, demonstrate exceptional effectiveness and stability. These include foam inhibition, defoaming, very good long-term stability, and outstanding compatibility in aqueous and non-aqueous media. All of these factors are of great importance for modern processes in the field of surface technology.

[0018] EP 2094761 B1 describes polyoxyalkylene-polysiloxane block polymers and a process for their preparation by reacting the alcohol components with chloropolysiloxanes.

[0019] The chloropolysiloxanes used there are linear structures with α-ω chlorine functionality, which are mixed from cycles D4 and D5 in a specific ratio with dimethyldichlorosilane, possibly with the addition of water to control the chain length, and are then equilibrated by adding a so-called equilibration catalyst, such as sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, or iron(III) chloride. EP 2094761 B1 further states that, in the preferred use of iron(III) chloride as a catalyst for the production of the linear α-ω dichlorosiloxanes, prior removal of the catalyst with activated carbon is recommended to prevent undesirable discoloration caused by the presence of the iron catalyst.

[0020] An alternative to this process is to react alcohols or polyetherols with hydrogensiloxanes, in which hydrogen is bonded directly to the silicon. Under suitable conditions, the formation of the SiOC bond merely results in the elimination of hydrogen. This process, known as dehydrogenative condensation, can only be carried out in the presence of a catalyst. US 5,147,965 refers to a process described in Japanese patent publication JPS 4819941, in which a hydrogensiloxane is reacted with an alcohol in the presence of alkali metal hydroxides or alkali metal alkoxides. The disadvantage of this process is that the catalysts must be neutralized after the reaction is complete, and the resulting salt load, although significantly lower than that of the chlorosiloxane process, still requires laborious filtration.

[0021] EP 3 438 158 describes a process for the preparation of SiOC-linked polyethersiloxanes by transesterification of alkoxysiloxanes with polyetherols in the presence of zinc acetylacetonate as catalyst.

[0022] EP 0 475 440 describes a process in which hydrogen siloxanes are reacted with an alcohol by adding an organic acid in the presence of a platinum salt. The reaction requires the use of large amounts of organic acid (0.1 to 1 mol relative to alcohol), toluene as a solvent, and a platinum salt. Since both toluene and acid are undesirable in the final product, they must be removed after the reaction. Furthermore, platinum salts are not only expensive but also physiologically hazardous. There is a particular demand for platinum-free products in the cosmetics industry.

[0023] The process described in J. Boyer, RJP Corriu, R. Perz, C. Reye, J. Organomet. Chem. 1978, 157, 153-162, does not require the use of heavy metals. Salts such as potassium tartrate, phthalate, or formate are used as heterogeneous catalysts. However, the reactions require the equimolar use of the salts relative to the SiH units and are only successful at high temperatures of approximately 180°C. Both the harsh conditions and the large amounts of salt required make this process unattractive for technical and industrial scale applications.

[0024] In patent applications DE 10 312 636 and DE 10 359 764, boron-containing catalysts are used for the dehydrogenative condensation of hydrogen siloxanes and alcohols. While these dehydrogenative processes for SiOC bond formation are attractive, particularly with regard to the avoidance of liquid and / or solid by-products, the use of costly and toxic catalysts, such as tris(pentafluorophenyl)borane, as well as the safe handling of the hydrogen gas produced during synthesis, hamper widespread application of the technology on an industrial scale.

[0025] The present invention is therefore based on the object of providing a process for the preparation of linear SiOC-linked polyethersiloxane block polymers of the structure type CB-(AB) a -C1, which does not have the disadvantages known from the prior art with regard to the use of the chlorosiloxane.

[0026] Surprisingly, it has now been found that a simple chlorine-free approach to polyoxyalkylene polysiloxane block polymers of the general formula (I) CB-(AB) a -C1 (I) wherein A = a polyoxyalkylene block of the general formula (C n H 2n O) b -, B = a polysiloxane block of the general formula (SiR 2 O) c -, C, C1 = identical or different alkoxypolyoxyalkylene radicals of the general formula (II) ZO-[CH 2 -CH(R 1< )O] d - (II) With Z = an alkyl, alkylene, aryl or alkylaryl radical, or C, C1 = an alkyl radical with the proviso that C or C1 has an alkoxypolyoxyalkylene radical of the general formula (II) with Z = hydrogen, or C, C1 = identical or different alkoxypolyoxyalkylene radicals of the general formula (II) with Z = a hydrogen with the proviso that C or C1 has an alkoxypolyoxyalkylene radical of the general formula (II) with Z = an alkyl, alkylene, aryl or alkylaryl radical, R = identical or different C 1-4 -alkyl radicals or phenyl radicals with the proviso that at least 90% of the radicals R are methyl radicals, R 1< = identical or different hydrogen, C 1-12 -alkyl radicals or phenyl radicals, a = 1 to 20,b = a mean value of 10 to 130, c = 3 to 100, d = independently in C / C1 values ​​of 2 to 20 with the proviso that the mean value is in the range 2 to < 15, n = 2 to 12 with a mean numerical value of 2.7 to 4.0, by reacting finally equilibrated α,ω-diacetoxy-polydimethylsiloxanes with a mixture consisting of at least one polyether polyol, preferably a polyether diol, and at least one polyether monool or at least one monohydric alcohol.

[0027] Preferably, final equilibrated α,ω-diacetoxy-polydimethylsiloxanes according to the following formula (III) where R 2< is an alkyl radical having 1 to 4 carbon atoms or a phenyl radical, but preferably more than 90% of the radicals R 2< are methyl radicals and x = 2 ≤ x ≤ 250, preferably 5 ≤ x ≤ 100, particularly preferably 10 ≤ x ≤ 30.

[0028] Access to acetoxy-functional polysiloxanes has been described in the literature. The previously unpublished European patent applications with the application numbers EP 18172882.5, EP 18172876.7, EP 18189072.4, EP 17195510.7, EP 17204277.2, EP 18189073.2, and EP 18210035.4 are dedicated to the preparation of trifluoromethanesulfonic acid-based, equilibrated acetoxysiloxanes of the linear structure type.

[0029] As a reference to the M, D, T, Q nomenclature used in this document to describe the building blocks of organopolysiloxanes, see W. Noll, Chemistry and Technology of Silicones, Verlag Chemie GmbH, Weinheim (1960), page 2 ff.

[0030] Following the teaching of EP 18189073.2, for example, cyclic polysiloxanes, in particular comprising D4 and / or D5, and / or mixtures of cyclically branched polysiloxanes of the D / T type are reacted with acetic anhydride and with the addition of acetic acid using trifluoromethanesulfonic acid as catalyst. Furthermore, EP 18189073.2 states that both mixtures of cyclic-branched polysiloxanes of the D / T type, which consist exclusively of polysiloxanes containing D and T units and whose total proportion of the D and T units present in the siloxane matrix, which contain Si-alkoxy and / or SiOH groups and which can be determined using 29Si NMR spectroscopy, is less than 2 mol percent, preferably less than 1 mol percent, and that they further advantageously contain at least 5 wt.-% siloxane cycles, such as preferably octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and / or mixtures thereof, as well as mixtures of cyclic-branched siloxanes containing exclusively D and T units, the total proportion of the D and T units present in the siloxane matrix, which contain Si alkoxy and / or SiOH groups, which can be determined by 29Si NMR spectroscopy, being greater than 2 and less than 10 mol percent, are particularly suitable for the production of end-equilibrated polysiloxanes containing acetoxy functions.

[0031] The not yet published European application 18210035.4 also describes (i) reaction systems for the preparation of polysiloxanes carrying acetoxy functions, comprising a) silanes and / or polysiloxanes carrying alkoxy groups and / or b) silanes and / or polysiloxanes carrying acetoxy groups, c) silanes and / or polysiloxanes carrying hydroxy groups, c) optionally simple polysiloxane cycles and / or DT cycles, d) a reaction medium comprising acetic anhydride, perfluoroalkanesulfonic acid and preferably acetic acid, (ii) a process for the preparation of linear or branched polysiloxanes carrying acetoxy functions.According to the above-mentioned application, it is possible, for example, to obtain a branched polysiloxane bearing terminal acetoxy groups by reacting a branched polysilicone equilibrate (= pre-equilibrate) bearing terminal alkoxy groups as the sole reactant with a reaction medium consisting of acetic anhydride, trifluoromethanesulfonic acid and acetic acid.

[0032] It is preferably conceivable to use polysiloxanes with Q units in addition to polysiloxanes having D and T units, with the proviso that in these mixtures the proportion of Si atoms originating from Q units is ≤ 10 mass% to ≥ 0 mass%, preferably ≤ 5 mass% to ≥ 0 mass%, where the lower limit can be > 0 or = 0 mass%, but in particular > 0 mass%, in each case based on the totality of all Si atoms.

[0033] The provision of mixtures of cyclic-branched polysiloxanes of the D / T type, which contain polysiloxanes having D and T units as well as those with Q units, is readily possible for the person skilled in the art, for example in analogy to the teaching of the cited documents using, for example, silicic acid esters (Si(OR)4) providing Q units.

[0034] Preferably, the final equilibrated α-ω diacetoxy-polydimethylsiloxanes according to the following formula (III) are obtainable from the reaction of Alkoxy group-bearing silanes and / or siloxanes, and / or hydroxy group-bearing silanes and / or siloxanes, and / or simple siloxane cycles and / or DT cycles, with acetic anhydride, superacid, in particular trifluoromethanesulfonic acid, and acetic acid.

[0035] Preferably, a silane and / or siloxane containing alkoxy groups and at least one T and / or Q group and / or DT cycles can be used to prepare the final equilibrated α,ω-diacetoxy-polydimethylsiloxanes according to formula (III).

[0036] According to a preferred embodiment of the invention, acetic acid is added in amounts of 0.4 to 3.5 percent by weight, preferably 0.5 to 3 percent by weight, more preferably 0.8 to 1.8 percent by weight, particularly preferably in amounts of 1.0 to 1.5 percent by weight, based on the reaction matrix consisting of acetic anhydride and cyclic polysiloxanes comprising D4 and / or D5, or consisting of acetic anhydride, and mixtures of cyclically branched polysiloxanes of the D / T type, optionally also with Q units, or consisting of cyclic polysiloxanes comprising D4 and / or D5, and mixtures of cyclically branched polysiloxanes of the D / T type.

[0037] According to a preferred embodiment of the invention, the catalyst trifluoromethanesulfonic acid is used in amounts of 0.1 to 1.0 mass percent, preferably 0.1 to 0.3 mass percent, based on the reaction matrix consisting of acetic anhydride and cyclic polysiloxanes, in particular comprising D4 and / or D5, and / or cyclic-branched polysiloxanes of the D / T type, optionally also with Q units.

[0038] The term "finally equilibrated" means that the equilibrium has been reached, which occurs at a temperature of 23°C and a pressure of 1013.25 hPa. The total cycle content determined by gas chromatography can be used as an indicator for the achievement of the equilibrium. This is defined as the sum of the D4, D5, and D6 contents relative to the siloxane matrix and determined after derivatization of the α,ω-diacetoxypolydimethylpolysiloxanes to the corresponding α,ω-diisopropoxypolydimethylpolysiloxanes or after derivatization of the branched acetoxypolysiloxanes to the corresponding branched isopropoxysiloxanes. The use of acetic acid according to the invention makes it possible to easily reduce the otherwise usual equilibrium fractions of approximately 8 weight percent of the total cycle content for the branched acetoxypolysiloxanes.Accordingly, a preferred embodiment is when equilibrium fractions of the total cycle content of less than 8, preferably less than 7, weight percent are undercut for the branched acetoxypolysiloxanes. The derivatization to the branched isopropoxypolysiloxanes is deliberately chosen to prevent a thermally induced cleavage reaction of the α,ω-diacetoxypolydimethylpolysiloxanes or the branched acetoxypolysiloxanes that may occur under the conditions of gas chromatographic analysis (for the cleavage reaction, see, among others, J. Pola et al., Collect. Czech. Chem. Commun. 1974, 39(5), 1169-1176 and also W. Simmler, Houben-Weyl, Methods of Organic Chemistry, Vol. VI / 2, 4th Edition, O-Metal Derivatives of Organic Hydroxy Compounds, p. 162 ff.).

[0039] Preferably, polyether polyols selected from polyether diols, polyether polyols or mixtures of polyether diols and polyether polyols are used for component A of formula (I).

[0040] The polyether polyols are preferably prepared by addition of alkylene oxides, according to the invention preferably ethylene oxide, propylene oxide, butylene oxide, styrene oxide, preferably mixed products of at least two monomer units, in particular of ethylene oxide and propylene oxide, to polyhydric starter alcohols of the general formula R 3< -[OH] e where R 3< = an e-valent hydrocarbon radical and e = 2 to 6, preferably 2 to 3, by the alkoxylation processes known in the art. As starter alcohols, in principle all straight-chain or branched, at least dihydric alcohols can be used. Preference is given according to the invention to di- and / or trihydric alcohols such as in particular ethanediol, propanediol, butanediol, hexanediol, trimethylolpropane, which can be used alone or as a mixture.

[0041] According to a preferred embodiment, the polyether polyols consist essentially of oxyethylene units or oxypropylene units, preferred are mixed oxyethylene and oxypropylene units with an oxyethylene content of about 1 to 70 percent by weight and 99 to 30 percent by weight of oxypropylene, based on the total content of oxyalkylene units in the block.

[0042] According to the invention, polyether diols in which ethylene oxide (EO) and propylene oxide (PO) are present as copolymers are preferred. Particularly preferred are EO / PO copolymers that have a block-like structure and contain an EO content of approximately 1 to 30 wt. %, based on the total content of oxyalkylene units.

[0043] For component C, C1 of formula (I), it is preferred to use a polyether monool and / or a monohydric C1 - C18 alcohol selected from methanol, ethanol, propanol, isopropanol, butanol and isobutanol.

[0044] The polyether monools can basically be prepared in the same way as the polyether polyols, with the modification that monofunctional compounds Z 1< -OH are used as starter alcohols, wherein Z 1< can be an optionally branched and / or multiple bond-containing alkyl, alkylene, alkylaryl, or aryl radical having 1 to 18 C atoms, preferably 1 to 10 C atoms.

[0045] Preferably, the molar ratio of finally equilibrated α,ω-diacetoxy-polydimethylsiloxanes to mixture consisting of at least one polyether polyol, preferably a polyether diol, and at least one polyether monool or at least one monohydric alcohol is in the range of 1.01 to 3.00, preferably in the range of 1.01 to 2.00, most preferably in the range of 1.01 to 1.50

[0046] Preferably, the reaction, ie the reaction of finally equilibrated α-ω diacetoxy-polydimethylsiloxanes according to formula (III) with a mixture consisting of at least one polyether polyol, preferably a polyether diol, and at least one polyether monool or at least one monohydric alcohol, is carried out at temperatures of 20°C to 180°C, preferably at temperatures of 60°C to 150°C.

[0047] In a preferred embodiment, the bases to be used are selected from the alkali and / or alkaline earth carbonates and / or hydrogen carbonates and / or amines, most preferably gaseous ammonia.

[0048] Known to those skilled in the art, the use of simple solid bases is also possible. Taking into account the poor solubility of the alkali or alkaline earth carbonates and / or bicarbonates in the reaction system, higher excesses of these are selected according to the invention, corresponding to at least 2000 times the stoichiometric equivalent of the trifluoromethanesulfonic acid contained in the α,ω-diacetoxypolydimethylsiloxane.

[0049] As a technical alternative for carrying out the SiOC bonding reaction, it is known to use buffer mixtures consisting of sodium trichloroacetate and trichloroacetic acid, or sodium acetate and trichloroacetic acid, both dissolved in acetic acid. Here, too, the amount of base contained in the buffer mixtures is usually calculated such that it corresponds to at least the stoichiometric equivalent, preferably 2 to 3 times the stoichiometric equivalent, of the trifluoromethanesulfonic acid contained in the α,ω-diacetoxypolydimethylsiloxane used.

[0050] Regarding the amount of acetic acid used to dissolve the buffer mixture, the unpublished inventions state that it is preferably chosen so that it is sufficient to produce a clear buffer solution free of solid salt components, which can be metered into the reaction matrix without loss. Excessive amounts of acetic acid are not critical for the successful implementation of the process according to the invention, but large amounts are also not advantageous, since it must subsequently be removed from the reaction matrix.

[0051] Given the known tendency of acetoxysiloxanes to condense, bases that, due to their chemical composition, do not introduce water into the reaction system are particularly preferred. Thus, anhydrous carbonates are preferred over bicarbonates, and bases free of water of hydration are preferred over bases containing water of hydration.

[0052] According to a preferred embodiment of the invention, alkanes, cycloalkanes, alkyl aromatics, end-capped polyethers and / or emollient esters, such as the esters derived from lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, isostearic acid, ricinoleic acid, and behenilic acid combined with cetyl, stearyl, isostearyl, oleyl, octyldodecyl, myristyl and behenyl alcohol or glycerol, preferably myristyl myristate, can be used as inert solvents.

[0053] In a preferred embodiment, the reaction is carried out solvent-free with a mixture consisting of at least one polyether polyol, preferably a polyether diol, and at least one polyether monool or at least one monohydric alcohol.

[0054] Preferably, the weight-average molecular weight of each polysiloxane block (B) is between 650 and 6500 g / mol, preferably 800 to 1500 g / mol, particularly preferably 1000 to 1200 g / mol.

[0055] The polydimethylsiloxane-polyoxyalkylene block copolymer produced by the process according to the invention has a weight-average molecular weight of at least 2,000 g / mol to approximately 160,000 g / mol, preferably 4,000 g / mol to approximately 50,000 g / mol, particularly preferably 5,000 g / mol to approximately 36,000 g / mol. The determination of the average molecular weights is based on known methods of GPC analysis.

[0056] To ensure increased storage stability, the linear SiOC-linked polyether siloxanes produced by the process according to the invention can also be mixed with small amounts of organic amines, such as N-methylmorpholine, triisopropanolamine, or triethanolamine. This corresponds to a preferred embodiment of the invention.

[0057] The invention also further relates to the use of the SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers according to formula (I), prepared by the process according to the invention, as surface-active additives for the production of PU foam stabilizers, defoamers, deaerators, emulsifiers, demulsifiers and paint and leveling additives.

[0058] It is also conceivable to use the SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers prepared by the process according to the invention for the production of diesel defoamers, water repellents, polymer dispersions, adhesives or sealants, paper towels; cleaning and care formulations for household or industrial applications, in particular for the production of fabric softeners, cosmetic, pharmaceutical and dermatological compositions, in particular cosmetic cleaning and care formulations, hair treatment compositions and hair aftertreatment compositions; building material compositions, and thermoplastic moldings.

[0059] The SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers produced by the process according to the invention can also be used as processing aids in the extrusion of thermoplastics, as adjuvant in crop protection, as additives for cleaning and care of hard surfaces, for the surface treatment of fibers, particles or fabrics, in particular for the finishing or impregnation of textiles, or in the coating of fillers. Methods

[0060] The following examples serve solely to explain this invention to the person skilled in the art and do not represent any limitation of the claimed subject matter. The determination of water content according to the invention is basically carried out using the Karl Fischer method based on DIN 51777, DGF E-III 10 and DGF C-III 13a.

[0061] For the purposes of this invention, the 29< Si NMR samples are measured at a measurement frequency of 79.49 MHz in a Bruker Avance III spectrometer equipped with a 287430 probe head with a 10 mm slit width at 22°C, dissolved in CDCl 3 and compared with tetramethylsilane (TMS) as an external standard [d( 29< Si) ​​= 0.0 ppm]. The 29< Si NMR spectroscopy was used for reaction monitoring in all examples.

[0062] The gas chromatograms were recorded on a GC 7890B from Agilent Technologies equipped with a HP-1 column (30 m x 0.32 mm ID x 0.25 µm dF) (Agilent Technologies No. 19091Z-413E) and hydrogen as the carrier gas with the following parameters: Detector: FID; 310°C Injector: Split; 290°C Mode: constant flow 2 mL / min Temperature program: 60°C with 8°C / min -150°C with 40°C / min - 300°C 10 min.

[0063] As an indicator for the achievement of the equilibrium, the total cycle content determined by gas chromatography is defined as the sum of the D4, D5, D6 contents based on the siloxane matrix and determined after the derivatization of the α,ω-diacetoxypolydimethylsiloxanes to the corresponding α,ω-diisopropoxy-polydimethylsiloxanes. The derivatization to the α,ω-diisopropoxy-polydimethylsiloxanes is deliberately chosen in order to prevent a thermally induced cleavage reaction of the α,ω-diacetoxy-polydimethylsiloxanes which may occur under the conditions of gas chromatographic analysis (for the cleavage reaction see, among others, J. Pola et al., Collect. Czech. Chem. Commun. 1974, 39(5), 1169-1176 and also W. Simmler, Houben-Weyl, Methods of Organic Chemistry, Vol. VI / 2, 4th Edition, O-Metal Derivatives of Organic Hydroxy Compounds p. 162 ff)).

[0064] The polyetherdiols used have a water content of approximately 0.2% by mass and are used without further pre-drying. Toluene and alkylbenzene (C 10 -C 13 ) have a water content of 0.03% by mass and are also used without pre-drying.

[0065] The OH number of the polyetherdiols is determined according to DGF CV 17 a (53) or according to Ph. Eur. 2.5.3 Method A, whereby the hydroxyl groups of the sample to be analyzed are first acetylated with acetic anhydride in the presence of pyridine and then, in a differential titration (blank sample, taking into account the acetic anhydride excess), the released acetic acid is titrated as consumption of KOH in mg per gram of polyetherdiol. Example a) Preparation of a fully equilibrated, acetoxy-terminated, linear polydimethylsiloxane

[0066] In a 1000 ml four-necked flask equipped with a precision glass stirrer, internal thermometer, and attached reflux condenser, 77.3 g (0.757 mol) of acetic anhydride, 732.8 g (1.98 mol) of decamethylcyclopentasiloxane (D 5 ), and 24.3 g of acetic acid (3.0 wt.% based on the total mass of the reactants) are placed with stirring. 1.62 g (0.88 ml) of trifluoromethanesulfonic acid (0.2 wt.% based on the total mass) are added and the mixture is rapidly heated to 150°C. The initially slightly cloudy reaction mixture is left at this temperature for 4 hours with continued stirring.

[0067] After cooling the mixture, a colorless-clear, easily mobile liquid is isolated, the 29< Si NMR spectrum of which confirms the presence of Si acetoxy groups in a yield of approximately 93% based on the acetic anhydride used, corresponding to an α,ω-diacetoxypolydimethylsiloxane with an average total chain length of approximately 14. Conversion of α,ω-diacetoxypolydimethylsiloxane into the corresponding α,ω-diisopropoxypolydimethylsiloxane for analytical characterization

[0068] Immediately after synthesis, 50.0 g of this trifluoromethanesulfonic acid, equilibrated α,ω-diacetoxypolydimethylsiloxane are mixed with 11.3 g of isopropanol dried over molecular sieves in a 250 ml four-neck round-bottom flask equipped with a precision glass stirrer, internal thermometer, and attached reflux condenser while stirring at 22°C. The reaction mixture is then subjected to alkalinization (moist universal indicator paper) by passing in gaseous ammonia (NH 3 ) and stirred for a further 45 minutes at this temperature. The precipitated salts are removed using a pleated filter.

[0069] A colorless, clear liquid is isolated, the accompanying 29< Si NMR spectrum of which confirms the quantitative conversion of the α,ω-diacetoxypolydimethylsiloxane into an α,ω-diisopropoxypolydimethylsiloxane.

[0070] An aliquot of this α,ω-diisopropoxypolydimethylsiloxane is taken and analyzed by gas chromatography. The gas chromatogram shows the following concentrations (in mass percent): D 4 D 5 D 6 Total (D 4 - D 6 ) Isopropanol content 4,09 % 2,62 % 0,86 % 7,57 % 4,60 % b) Preparation of a SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymer of the structure type CB-(AB) a -C1

[0071] In a 250 ml four-necked flask equipped with a KPG glass paddle stirrer, internal thermometer and attached reflux condenser, a mixture of 67.9 g of a polyetherdiol with an average molecular weight of 2671 g / mol (determined by OH number) with a mass ratio of ethylene oxide to propylene oxide of 60:40 and 4.0 g of a butanol-initiated polyetherol (propylene oxide content of 100%) with a molecular weight of 600 g / mol (molar weight determined by OH number) is mixed with a solution of sodium acetate and trichloroacetic acid (0.06 g sodium acetate (0.2% by weight based on the acetoxysiloxane) and 0.21 g trichloroacetic acid (0.2% by weight based on the total batch consisting of the polyether mixture and acetoxysiloxane)) in 5 g of acetic acid while stirring. Then, 28.0 g of the trifluoromethanesulfonic acid α,ω-diacetoxypolydimethylsiloxane from step a) are added. The reaction mixture is heated to 70°C and maintained at this temperature for 3 hours with vigorous stirring.The attached reflux condenser is replaced by a short distillation bridge and the reaction mixture is freed from volatiles at a bottom temperature of 100°C and an applied auxiliary vacuum of 1 mbar.

[0072] After cooling to 70°C, 17 g of isopropanol are added while stirring and the mixture is allowed to react at this temperature for 3 hours. Then, 2.4 g of sodium carbonate (2.0 wt.% based on the total mixture) are added and stirred for a further 2 hours.

[0073] After cooling to 25°C, the solid components are separated using a pleated filter and excess isopropanol is removed from the clear filtrate by distillation at 70°C / 1 mbar auxiliary vacuum on a rotary evaporator.

[0074] A colorless copolymer with a viscosity of 1750 mPas is isolated, the corresponding 29Si-NMR spectrum of which confirms the desired structure (20% isopropoxy-substituted Si end groups relative to 80% of the SiOC bonds resulting from the polyether-Si linkage). Summary

[0075] The invention relates to processes for the preparation of SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the general formula (I) CB-(AB) a -C1 by reacting end-equilibrated α,ω-diacetoxy-polydimethylsiloxanes with a mixture consisting of at least one polyether polyol, preferably a polyether diol, and at least one polyether monool or at least one monohydric alcohol.

Claims

1. Process for producing SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the general formula (I)         C-B-(AB)a-C1     (I) in which A = a polyoxyalkylene block of the general formula (CnH2nO)b-, B = a polysiloxane block of the general formula (SiR2 O)c-, C,C1 = identical or different alkoxypolyoxyalkylene radicals of the general formula (II)         Z-O-[CH2-CH(R1)O]d-     (II) where Z = an alkyl, alkylene, aryl or alkylaryl radical, or C,C1 = an alkyl radical with the proviso that C or C1 possesses an alkoxypolyoxyalkylene radical of the general formula (II) where Z = hydrogen, or C,C1 = identical or different alkoxypolyoxyalkylene radicals of the general formula (II) where Z = a hydrogen with the proviso that C or C1 possesses an alkoxypolyoxyalkylene radical of the general formula (II) where Z = an alkyl, alkylene, aryl or alkylaryl radical, R = identical or different C1-4-alkyl radicals or phenyl radicals with the proviso that at least 90% of the radicals R are methyl radicals, R1 = identical or different hydrogen radicals, C1-12-alkyl radicals or phenyl radicals, a = 1 to 20, b = an average value of from 10 to 130, c = 3 to 100, d = independently of one another in C / C1 values of from 2 to 20 with the proviso that the average value is in the range from 2 to < 15, n = 2 to 12 with an average numerical value of from 2.7 to 4.0, characterized in that end-equilibrated α,ω-diacetoxypolydimethylsiloxanes are reacted with a mixture consisting of at least one polyether polyol, preferably a polyether diol, and at least one polyether monool or at least one monohydric alcohol.

2. Process according to Claim 1, characterized in that end-equilibrated α,ω- diacetoxypolydimethylsiloxanes of formula (III) below where R2 is an alkyl radical having 1 to 4 carbon atoms or a phenyl radical, but preferably more than 90% of the radicals R2 are methyl radicals and x = 2 ≤ x ≤ 250, preferably 5 ≤ x ≤ 100, particularly preferably 10 ≤ x ≤ 30, are used.

3. Process according to Claim 1 or 2, characterized in that the end-equilibrated, α,ω-diacetoxypolydimethylsiloxanes of formula (III) are obtainable from the reaction of • silanes and / or siloxanes bearing alkoxy groups, and / or • silanes and / or siloxanes bearing hydroxy groups, and / or • simple siloxane cycles and / or DT cycles, • with acetic anhydride, superacid, in particular trifluoromethanesulfonic acid, and acetic acid.

4. Process according to any of Claims 1 to 3, characterized in that, for the production of the end-equilibrated α,ω-diacetoxypolydimethylsiloxanes of formula (III), a silane and / or siloxane bearing alkoxy groups and containing at least one T and / or Q group, and / or DT cycles are used.

5. Process according to any of Claims 1 to 4, characterized in that, for component A of formula (I), polyether polyols selected from polyether diols, polyether polyols or mixtures of polyether diols and polyether polyols are used.

6. Process according to any of Claims 1 to 4, characterized in that, for component C, C1 of formula (I), a polyether monool or a monohydric C1 - C18 alcohol selected from methanol, ethanol, propanol, isopropanol, butanol, isobutanol is used.

7. Process according to any of the preceding claims, characterized in that the molar ratio of end-equilibrated α,ω-diacetoxypolydimethylsiloxanes to the mixture consisting of at least one polyether polyol, preferably a polyether diol, and at least one polyether monool or at least one monohydric alcohol is in the range from 1.01 to 3.00, preferably in the range 1.01 to 2.00, very particularly preferably in the range 1.01 to 1.50.

8. Process according to any of the preceding claims, characterized in that the reaction with a mixture consisting of at least one polyether polyol, preferably a polyether diol, and a polyether monool or a monohydric alcohol is conducted at temperatures of 20°C to 180°C, preferably at temperatures of 60°C to 150°C.

9. Process according to any of the preceding claims, characterized in that the bases to be used are selected from the alkali metal and / or alkaline earth metal carbonates and / or hydrogencarbonates and / or amines, very particularly preferably gaseous ammonia.

10. Process according to any of the preceding claims, characterized in that inert solvents used are alkanes, cycloalkanes, alkylaromatics, end-capped polyethers and / or emollient esters, such as the esters derived from lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, isostearic acid, ricinoleic acid and behenic acid combined with cetyl, stearyl, isostearyl, oleyl, octyldodecyl, myristyl and behenyl alcohol or glycerol, preferably myristyl myristate.

11. Process according to any of the preceding claims, characterized in that the reaction with a mixture consisting of at least one polyether polyol, preferably a polyether diol, and a polyether monool or a monohydric alcohol is effected solventlessly.

12. Process according to any of the preceding claims, characterized in that the weight-average molecular weight, determined on the basis of the known methods of GPC analysis, of each polysiloxane block (B) is between 650 to 6500 g / mol, preferably 800 to 1500 g / mol, particularly preferably 1000 to 1200 g / mol.

13. Process according to any of the preceding claims, characterized in that the polydimethylsiloxane-polyoxyalkylene block copolymer has a weight-average molecular weight, determined on the basis of the known methods of GPC analysis, of at least 2000 g / mol to approx. 160 000 g / mol, preferably 4000 g / mol to approx. 50 000 g / mol, in particular 5000 g / mol to approx. 36 000 g / mol.

14. Use of the SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers produced by a process according to any of Claims 1 - 13 for the production of diesel defoamers, of hydrophobizing agents, of polymer dispersions, of adhesives or sealants, of paper towels; of cleaning and care formulations for the household or for industrial applications, in particular for the production of fabric softeners, of cosmetic, pharmaceutical and dermatological compositions, in particular cosmetic cleaning and care formulations, hair treatment agents and hair aftertreatment agents; of construction material compositions, of thermoplastic shaped bodies.

15. Use of the SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers produced by a process according to any of Claims 1 - 13 as processing aid in the extrusion of thermoplastics, as adjuvant in crop protection, as additive for the cleaning and care of hard surfaces, for the surface treatment of fibres, particles or fabrics, in particular for the finishing or impregnation of textiles, or in the coating of fillers.