EP3794060A1

EP3794060A1 - Linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structural type aba

Info

Publication number: EP3794060A1
Application number: EP19721304.4A
Authority: EP
Inventors: Wilfried Knott; Horst Dudzik; Frauke Henning
Original assignee: Evonik Operations GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2018-05-17
Filing date: 2019-05-07
Publication date: 2021-03-24
Also published as: CA3099861A1; CN112119111A; US11359056B2; US20210171719A1; WO2019219452A1

Abstract

The invention relates to equilibrated trifluoromethanesulphonic acid diacetoxypolydimethylsiloxanes, processes for the production thereof and to SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structural type ABA, as well as to a process for the production thereof, wherein the production of SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structural type ABA is carried out by reacting trifluoromethanesulphonic acid acetoxysiloxane with polyetherols optionally in the presence of a buffer mixture and optionally an additional condensation catalyst and optionally in the presence of an inert solvent.

Description

Linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA

The invention relates to equilibrated trifluoromethanesulfonic acid a, w-diacetoxypolydimethylsiloxanes, to processes for their preparation and to SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA and to processes for their preparation.

For the production of the economically significant class of SiOC-linked polyether siloxanes, also referred to as silicone polyethers or siloxane-polyether copolymers, use is made according to the current state of the art of several process variants.

Classically, SiOC linkages are formed by the reaction of a siloxane with a leaving group attached to the silicon atom (e.g., halogen) and an alcohol or polyetherol. The latter is usually obtained beforehand by alkoxylation of monohydroxy-functional starter compounds such as butanol with alkylene oxides. Especially chlorosiloxanes are used as starting compounds for this type of reaction. However, chlorosiloxanes are difficult to handle because they are extremely reactive. Their use is further associated with the disadvantage that the hydrogen chloride formed in the course of the reaction limits handling to corrosion-resistant equipment and leads to ecological problems. In addition, in the presence of chlorosiloxanes and alcohols or Polyetheroien organic chlorine compounds arise which are not desirable for toxicological reasons. Furthermore, it is not easy to achieve a quantitative conversion in the reaction of a chlorosiloxane with an alcohol or polyetherol, so that the OH-functional component often has to be used in a stoichiometric excess based on the SiCI functions of the siloxane component. The use of a polyether excess means in practice that unavoidably larger amounts of unreacted excess polyethers are present in the silicone polyethers thus prepared, which reduce the concentration of surfactant silicone polyethers and impair the performance properties of the target products. Frequently, the Chlorsiloxanroute bases must be used as HCI scavenger to achieve good sales. The use of these bases produces large amounts of salt, the removal of which is difficult on an industrial scale.

As an alternative to this process, it is possible to react alcohols or polyetherois with hydrogen siloxanes in which hydrogen is bonded directly to the silicon. Under suitable conditions, formation of the SiOC bond only results in the elimination of hydrogen. This dehydrogenative condensation takes place only in the presence of a catalyst. US-A-5147965 refers to a process described in Japanese Patent Publication JP480-19941 in which a hydrogen siloxane is reacted with an alcohol with addition of alkali metal hydroxides or alkali metal alkoxides. A disadvantage of this method is that the catalysts must be neutralized after completion of the reaction and the resulting salt load, although less than that of the chlorosiloxane process, but still consuming must be filtered off. EP-A-0475440 describes a process in which hydrogen siloxanes are reacted with an alcohol with the addition of an organic acid in the presence of a Pt salt. For the reaction it is indispensable that both large Amounts of organic acid (0.1 to 1 mol based on alcohol), toluene can be used as a solvent and a platinum salt. Since both toluene and acid in the final product are undesirable, they must be separated again after the end of the reaction. Platinum salts are not only expensive, but from a physiological point of view also not safe. Especially in the field of the cosmetic industry, there is a desire for products free of platinum.

Without the use of heavy metals, J. Boyer, R.J.P. Corriu, R. Perz, C. Reye, J. Organomet. Chem. 1978, 157, 153-162. Thereby, salts such as e.g. Potassium tartrate, phthalate or formate used as heterogeneous catalysts. However, the reactions require the equimolar use of the salts based on the SiH units and succeed only at high temperatures of about 180 ° C. Both the drastic conditions and the large quantities of salt required make this process unattractive on a technical scale.

The patent applications DE10312636 and DE10359764 use boron-containing catalysts for the dehydrogenative condensation of hydrogen siloxanes and alcohols. As attractive as these dehydrogenative SiOC linking processes are, especially with regard to the avoidance of liquid and / or solid by-products, there are both the use of costly and toxic catalysts, such as tris (pentafluorophenyl) borane, and the safe handling of the In the synthesis of hydrogen gas resulting from a wide application of the technology.

Against this background, the technical problem to be solved is to enable the provision of linear SiOC-linked polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA, overcoming the difficulties discussed.

Surprisingly, it has now been found that the provision of linear, SiOC-linked polyethersiloxanes of the structure type ABA starting from cyclic siloxanes, in particular D ₄ and / or Ds, succeeds by equilibrating trifluoromethanesulfonsaures acetoxysiloxane with polyether monools in the presence of buffer mixtures and optionally an additional condensation catalyst and optionally in the presence of an inert solvent, wherein the equilibrated trifluoromethanesulfonsaure acetoxysiloxane is particularly obtainable by trifluoromethanesulfonic acid catalyzed reaction of cyclic siloxanes, in particular D ₄ and / or Ds, with acetic anhydride, preferably in the presence of acetic acid. This is an object of the invention. D ₄ is octamethylcyclotetrasiloxane. Ds stands for decamethylcyclopentasiloxane.

The relevant linear, SiOC-linked polyether siloxanes of the structure type ABA correspond to a further object of the invention and are advantageously characterized by a particularly high purity.

Additions to acetoxy-functional siloxanes are described in the literature.

Thus, the non-equilibrating opening of simple unbranched siloxane cycles with acetic anhydride to short-chain, chain-terminal acetoxy-carrying siloxanes in the presence of catalysts is known from a number of publications and protective rights applications. Borisov and Sviridova describe the opening of cyclic dimethylsiloxanes with acetic anhydride in the presence of catalytic amounts of iron (III) chloride to short-chain α, ω-acetoxysiloxanes (SN Borisov, NG Sviridova, J. Organomet. Chem., 1 1 (1968), 27-33). Lewis et al. in US4066680 is directed to the preparation of short-chain α, ω-siloxanediols, in which he reacts octamethylcyclotetrasiloxane with acetic anhydride and acetic acid on acid-treated bleaching earths and hydrolyzes the mixtures of short-chain α, ω-acetoxysiloxanes in alkaline water. In this case, Lewis writes that the acetic acid, which reduces the de facto space-time yield of the process and accounts for 2 to 20% of the reaction mixture, also functions as a co-catalyst in addition to its function as a solvent. However, the a, w-acetoxysiloxanes obtained as a precursor according to this teaching are in no way equilibrates, as is evident from Example 2 of the document, since the gas chromatographic analysis for the entire reaction mixture a share of 14.20% D ₄ or after deduction of a salary of 19.04% acetic acid contained in the mixture has a content of 17.53% D ₄ based on the pure siloxane matrix. Taking into account the content of the usually considered, low molecular weight cycles D3 (1, 55%), Ds (10.42%) and D6 (0.54), the content of cyclosiloxanes is 30.04%, well above that otherwise usual equilibrium proportion of about 13 percent by weight is expected in equilibrations (see WO 95/01983, page 1, lines 26 to 33).

US3346610 also discloses access to acetoxy group-bearing, short-chain siloxanes which is based on the metal halide-induced acetoxy modification of strained cyclic siloxanes by reacting them with acetoxy group-containing silicone compounds. A variety of Friedel-Crafts active metal halides act as a catalyst, with zinc chloride being preferred. A specific objective of US3346610 is the acetoxy modification of strained diorganosiloxane cycles, with deliberate avoidance of equilibration events.

The prior art thus relates to work which provide the opening of cyclic siloxanes - here sometimes strained cyclosiloxanes - with reactants containing acyloxy groups and whose objective is to obtain defined linear short-chain and siloxane species which are still to be separated by fractional distillation.

However, the molecular weight-defined, chain-pure, acetoxy-modified siloxane compounds synthesized in this way are not suitable for the preparation of organomodified siloxanes, in particular polyethersiloxanes, which are used in demanding technical applications, such as, for example. in the PU foam stabilization or in the defoaming of fuels, etc. take. Agents that effectively address such a field of application are always characterized by a broad polymer distribution comprising high, medium and low molecular weights, as the oligomers contained in them depending on their molecular weight and thus their diffusion behavior very often attributed differentiated surfactant tasks in different time windows of the respective process are.

Older routes, for example for the preparation of branched SiOC-linked silicone polyethers, include, among others, the acid-catalyzed reaction of chlorosilanes with acetic acid in the presence of siloxane cycles (US Pat. No. 4,380,451). In addition to the principal disadvantages of a chlorine chemistry outlined above, this process has its own property that the replacement of silicon-bonded chlorine by Acetoxy is a more imperfect, as is apparent from the (in ibid., Column 4, 1st line) proposed siloxane intermediate formula. Similarly problematic is the teaching of EP0000328B1 which describes a process for the preparation of linear and branched equilibrated organopolysiloxanes by reacting a chlorosilane or partial hydrolyzates thereof with organosiloxanes and monobasic carboxylic acids in the presence of an acidic equilibration catalyst. Turning to the GC analysis of the a, w-diacetoxy-polydimethylsiloxanes disclosed therein, it is stated (ibid., Page 6, line 30) that the chlorosiloxanes present in small amounts were not taken into account in the evaluation of the GC.

Also known are acyloxyorganopolysiloxanes and in particular organosiloxanes having terminal acyloxy groups as starting materials for subsequent reactions. For example, the acyloxy groups can be hydrolyzed in a diorganosiloxane, whereupon the hydrolyzate can be dehydrated and the dehydrated hydrolyzate polymerized to form a flowable diorganopolysiloxane. These flowable polysiloxanes are useful as starting materials for the preparation of viscous oils and rubbers which can be cured to silicone elastomers.

Organosiloxanes provided with terminal acyloxy groups can be obtained, for example, by reacting an alkylsiloxane and an organic acid and / or anhydride thereof in the presence of sulfuric acid as a catalyst. Such a process is described in US Pat. No. 2,910,496 (Bailey et al.). Although in principle organosiloxanes having terminal acyloxy groups are also obtained by this process, the disadvantage of the process is that the reaction product consists of a mixture of acyloxy-containing siloxanes and acyl-containing silanes of different composition. In particular, the teaching to this end states that alkylsiloxane copolymers composed of M, D and T units are cleaved by the process into trimethylacyloxysilane, di-acyloxydimethylsiloxane and methyltriacacylsilane. Thus Bailey obtained even after the 40 hour reaction of octamethylcyclotetrasiloxane with acetic anhydride and acetic acid at 136 to 147 ° C and after neutralization of the sulfuric acid used as a catalyst, separating the salts and removing water, residual acetic acid and acetic anhydride a complex mixture and in no way an equilibrate, which he then subjected to fractional distillation (see example, ibid.). The material identity of the resulting fractions II and IV remains unclear, so that it is difficult thereafter to obtain defined products, or to separate them in high yields from the mixture.

Referring to Bailey et al. (US2910496), DE-OS1545110 (A1) (Omietanski et al.) Teaches a process wherein an acyloxy group of an acyloxysiloxane is reacted with the hydroxyl group of a polyoxyalkylene hydroxypolymer to form a siloxane-oxyalkylene block copolymer and a carboxylic acid; Carboxylic acid is removed from the reaction mixture. The described therein, solvent and catalyst-free guided reactions sometimes require considerable reaction times (up to 1 1, 5 hours (Example 1), very high, product-loading reaction temperatures (150 to 160 ° C (Example 1) and the application of an auxiliary vacuum or Stripping the reaction matrix with dry nitrogen over the entire reaction time and, despite the harsh reaction conditions at the product stage, does not always achieve complete conversion (Example 9, ibid.). From a production engineering point of view, in particular the combination of high reaction temperatures and long reaction times as well as the unpredictable product quality are comparable to those of Omietanski et al. described process to the detriment.

No. 3,595,885 teaches a process for preparing equilibrated acyloxy-functionalized siloxanes starting from equilibrated chlorosiloxanyl sulfates by reaction with carboxylic acids and / or carboxylic acid salts and / or carboxylic acid anhydrides. The teaching teaches (column 5 / lines 72-74) that you must expect sulfuric acid-containing products (-SO4- and / or -OSO3H bonded to Si), if you use pure carboxylic acids and / or carboxylic anhydrides. However, the examples supporting the remaining carboxylic acid salt route also do not prove the freedom from sulfuric acid of the resulting acyloxysiloxanes, which is meaningless for the object of the substances described therein as components in cold-curing silicone rubbers, since they are reacted with hydroxy-functional silicones in the presence of a tin catalyst with hydrolysis of the Siloxanylsulfat functions brings to implementation. This chlorine route, which is characterized by questionable product quality, is therefore not suitable for demanding applications (see also Example IV, <0.5% chlorine content).

In addition, the statement there of equilibrated acyloxy-functionalized siloxanes is not applicable. If, for example, bridging sulfato groups incorporated in the silicone scaffolds are dissolved out by treatment with carboxylic acid salts, then shorter scission products closed with acyloxy groups are always formed, so that the resulting mixture, and in particular in comparison with the starting material, is by no means a true equilibrate.

Surprisingly, it has been found in the context of the present invention that equilibrated a, w-diacetoxy-polydimethylsiloxanes can be prepared by the reaction of siloxane cycles (in particular comprising D4 and / or Ds) with acetic anhydride in the presence of trifluoromethanesulfonic acid and preferably acetic acid.

Another object of the invention is thus a process for preparing trifluoromethanesulfonsaurer equilibrated a, w-Diacetoxypolydimethylsiloxane, wherein cyclic siloxanes, in particular comprising D4 and / or Ds, using trifluoromethanesulfonic acid as a catalyst and preferably acetic acid with acetic anhydride.

An exemplary, but also preferred embodiment in the context of the abovementioned process according to the invention provides, with good mixing of the reactants, to apply it with preferably 0.1 to 0.3% by weight of trifluoromethanesulfonic acid based on the entire reaction mass and then preferably to temperatures of 140 to 160 ° C for a period of 4 to 8 hours to heat. Here, from the initially slightly turbid reaction mixture, a clear, equilibrated trifluoromethanesulfonsaures a, w-diacetoxy-polydimethylsiloxane. These reaction products can advantageously be used after prolonged storage with good success for the production of SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA in the context of this invention. Understand the expert, under normal pressure conditions (1013.25 hPa) and at a constant ratio of acetic anhydride to cyclic siloxanes both the selected reaction temperature, and the selected amount of added catalyst (trifluoromethanesulfonic) and the selected reaction time affect the degree of acetylation achieved and thus the individual position of the equilibrium equilibrium which occurs under these conditions. Thus, the trifluoromethanesulfonic acids a, w-diacetoxypolydimethylsiloxanes prepared at the particularly preferred reaction temperature of 150 ° C. and at 0.1% by weight of trifluoromethanesulfonic acid a very constant acetylation degrees of about 80% by volume (about 20% by weight) after 6 hours of reaction time. % of free acetic anhydride) based on the amount of acetic anhydride used. Here, the amount of substance in Val corresponds to the amount of substance in moles multiplied by the respective stoichiometric valence. Acetanhydride has a stoichiometric valence of 2 because it is formally the source of two acetoxy groups. An increase in the reaction temperature to 160 ° C associated with an increase of the trifluoromethanesulfonic acid addition to 0.2% leads after 6 hours reaction time again very reproducible Acetylierungsgraden of about 90% by weight (with about 10% by volume of free acetic anhydride) based on the Amount of acetanhydride used. Considering that the trifluoromethanesulfonic represents a significant cost factor, within the scope of the inventive teaching, optimizations within the parameter field described can be easily made.

Thus, for the reproducible, industrial preparation of the a, w-diacetoxypolydimethylsiloxanes according to the invention, a few orienting laboratory experiments are sufficient to determine the individual position of the equilibrium equilibrium which remains constant under predetermined conditions with the help of ²⁹ Si NMR, supplemented by ¹³ C NMR. and to determine ¹ H NMR spectroscopy and thus determine the optimal production conditions.

In the context of the present invention, it has furthermore been found, unexpectedly, that the additional use of acetic acid in the process according to the invention for the preparation of trifluoromethanesulfonic acid-equilibrated a, w-diacetoxypolydimethylsiloxanes makes it possible to further improve the equilibration quality. The additional use of acetic acid therefore corresponds to a very particularly preferred embodiment of the invention. On the one hand, it has a positive effect on the achievement of the acetoxy functionalization and, in this respect, makes it possible to improve the yield based on the acetic anhydride used, but, above all, it ensures outstanding equilibration results even after a very short reaction time (for example after 4 hours / example 6).

As an indicator for the achievement of the equilibrium equilibrium, the total cyanogen content determined by gas chromatography can be defined as the sum of the T ₄ , Ds, D 6 contents based on the siloxane matrix and determined after the derivatization of the α, ω-diacetoxypolydimethylsiloxanes to the corresponding α, ω-diisopropoxypolydimethylsiloxanes be used. The use of acetic acid according to the invention here allows the problem-free falling below otherwise usual equilibrium proportions of about 13 weight percent. Accordingly, it corresponds to a preferred embodiment when equilibrium proportions of the total cycle content of less than 13, preferably less than 12 weight percent are realized in the linear a, w-Diacetoxypolydimethylsiloxanen. It thus corresponds to a particularly preferred embodiment of the present invention, when in the process for preparing trifluoromethanesulfonic acid-equilibrated a, w-diacetoxypolydimethylsiloxanes acetic acid in amounts of 0.4 to 3.5 weight percent, preferably 0.5 to 3 weight percent, preferably 0.8 to 1, 8 weight percent, particularly preferably in amounts of 1, 0 to 1, 5 weight percent based on the reaction matrix consisting of acetic anhydride and cyclic siloxanes is added.

Another object of the invention are trifluoromethanesulfonic acid, equilibrated a, w-Diacetoxypolydimethylsiloxane, the general formula

with R = methyl,

which has a mean chain length determined by ²⁹ Si-NMR spectroscopy of 0 <X <250, preferably 5 <X <100, particularly preferably 10 <X <30, and

0, 1 to 0.3 mass percent trifluoromethanesulfonic acid,

and 5 to 43% by volume, preferably 1 to 25% by weight, of free acetic anhydride, based on the

a, w-diacetoxypolydimethylsiloxane contain chemically bound acetic anhydride equivalent.

These are accessible via the method described above.

These inventive trifluoromethanesulfonic, equilibrated a, w-Diacetoxypolydimethylsiloxane react with polyether monools, even at moderate temperatures quickly and also completely to SiOC-linked polyethersiloxanes high purity.

The term "purity" used in the context of this invention in relation to the ABA-structured, SiOC-linked silicone polyethers relates in particular to their degree of halide and, in particular, their chloride freedom.

Chloride-free is always desirable and particularly required when the ABA-structured, SiOC-linked silicone polyethers as surfactant component, for example, to take in cleaning formulations for the cleaning of magnetic heads. The payment by credit cards brings with the skin fats, cosmetics, dust but also in particular with moisture (for example, skin swelling) afflicted credit cards in contact with a magnetic head or with Chip reading contacts. The permanent use of the credit card machine with a large number of credit cards and the concomitant buildup of soiling increase the likelihood of malfunctioning up to the non-acceptance of the credit card used. If the contact surfaces covered with metal oxide residues are cleaned with a cleaning fluid, the application of corrosion-promoting chloride ions must be avoided at all costs.

The linear ABA-structured, SiOC-linked polydimethylsiloxane-polyoxyalkylene- available by the process according to the invention, in which trifluoromethansulfonsaures, equilibrated a, w-Diacetoxypolydimethylsiloxan with polyether monools in the presence of buffer mixtures and optionally an additional condensation catalyst and optionally in the presence of an inert solvent Block copolymers are a further subject of the invention.

Particularly preferably usable buffer mixtures consist of sodium trichloroacetate and acetic acid or of sodium acetate and acetic acid. The use of these liquid buffer mixtures, in particular the buffer mixtures particularly preferred according to the invention, is advantageous from the point of view of production, in particular over the use of simple solid bases, since the metering of a liquid is always simpler than the handling of pulverulent solids. In particular, the use of the buffer mixtures according to the invention, especially of the preferred buffer mixtures, makes it possible to provide colorless or virtually colorless polyether siloxanes.

The linear ABA-structured, SiOC-linked polydimethylsiloxane-polyoxyalkylene block copolymers obtainable by the process according to the invention are of high purity and preferably have chloride contents <10 ppm and are particularly suitable, inter alia, for applications of the type described above. The determination of the chloride content can be carried out with Help established methods via potentiometric argentometry or ion chromatography (here in particular following the rule of ASTM D 7319-07 standard) done. Since corrosion phenomena are known to be caused both by the presence of inorganic chloride and by the presence of organochlorine compounds, chloride content within the scope of the inventive teaching always means the analytically detectable total chlorine content.

According to the invention, it has been found that the rapid and complete reaction of trifluoromethanesulfonic, equilibrated a, w-Diacetoxypolydimethylsiloxanen with Polyethemonoolen while avoiding discoloration of the reaction product in the presence of buffer mixtures and optionally performs an additional condensation catalyst such as trichloroacetic acid. The use of trichloroacetic acid corresponds to a particularly preferred embodiment of the invention.

In a preferred embodiment of the invention, the process for producing SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA is characterized in that

the polyethermonool is initially charged, if appropriate in the presence of an inert solvent, with buffer mixtures and, if appropriate, an additional condensation catalyst and then admixed with equilibrated a, w-diacetoxypolydimethylsiloxane trifluoromethanesulfonic acid, and then thermally separating the released and optionally present in the system acetic acid optionally using an azeotrope-forming solvent together with the solvent and the obtained SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymer neutralized by the addition of an auxiliary base, filtered and optionally endstabilisiert.

In this case, the amount of base used to charge the polyether monool in the buffer mixture is preferably such that it corresponds to at least the stoichiometric equivalent, preferably at least twice the stoichiometric equivalent of the trifluoromethanesulfonic acid contained in the α, ω-diacetoxypolydimethylsiloxane (see also Examples 2 and 3 ).

According to the invention, the buffer mixtures used already contain fractions of the condensation catalyst and in this case particularly preferably the condensation catalyst in the form of a salt. The present in trifluoromethanesulfonic a, w-Diacetoxypolydimethylsiloxan existing trifluoromethanesulfonic acid is neutralized in this way and sets the condensation catalyst from its salt in freedom.

Should the neutralization described here in the case of the trichloroacetic acid used particularly preferably according to the invention as the condensation catalyst already result in a release of from 0.2 to 0.5% by mass, based on the total amount of the reactants provided for the SiOC linking reaction (namely a, w-diacetoxypolydimethylsiloxane plus polyethermonool) lead, it will be dispensed with an optionally be applied with additional amounts of trichloroacetic acid for the successful rapid completion of the condensation reaction, which corresponds to a preferred embodiment of the invention.

The buffer mixtures particularly preferably used according to the invention comprise sodium trichloroacetate and acetic acid or comprise sodium acetate and acetic acid.

If the amount of the base used for charging the polyethermonool in the buffer mixture as described above is based on the trifluoromethanesulfonic acid equivalent derived from the α, ω-diacetoxypolydimethylsiloxane, the amount of trichloroacetic acid preferably used according to the invention depends on the total amount of the reactants a provided for the SiOC linking reaction a, w-diacetoxypolydimethylsiloxane plus polyethermonool).

According to the invention, the amount of trichloroacetic acid to be used in the context of a preferred embodiment is in the range of preferably 0.1 to 0.7 percent by mass, preferably between 0.2 and 0.5 percent by mass, based on the total amount of the reactants a, w-diacetoxypolydimethylsiloxane provided for the SiOC linking reaction plus polyether monool).

The amount of acetic acid used in a preferred embodiment for dissolving the buffer mixture is preferably chosen so that it is sufficient to produce a clear, free of solid salt buffer solution, which can be dosed lossless in the reaction matrix. On the other hand, additional amounts of acetic acid are of little significance for successfully carrying out the process according to the invention, but large amounts are also not advantageous, since they must then be removed again from the reaction matrix. In this context and owing to the crystalline habit of the trichloroacetic acid particularly preferably used in accordance with the invention, all the process variants which make it possible to prefer the condensation catalyst in the form of a solution and not as a solid, and most preferably together with the buffer mixture, in the industrial practice are to be preferred Reaction system bring.

The eventuality of the occurrence of discoloration is also related to the temperatures to which the reaction mixture is exposed, thus resulting in several preferred embodiments of the process according to the invention.

A further preferred embodiment provides that the trifluoromethanesulfonic acid, equilibrated a, w-diacetoxypolydimethylsiloxane with Polyethermonool (s) at temperatures of <25 ° C with stirring presents, and by a subsequent entries of a buffer mixture and optionally an additional condensation catalyst before heating the Reaction mixture of an undesirable discoloration of the reaction product effectively counteracted.

In a particularly preferred embodiment according to the invention, it is envisaged that buffer mixtures should be initially introduced into the polyetherol or polyetherol mixture intended for linking before the trifluoromethanesulfonic acid, equilibrated α, w-diacetoxypolydimethylsiloxane is added (cf., in particular, Examples 2 and 3). By optionally adding further condensation catalysts such as, for example, preferably trichloroacetic acid, a rapid reaction of the reactants is ensured. This reaction is preferably carried out at temperatures between 50 to 90 ° C and preferably for a period of 2 to 6 hours.

The avoidance of undesirable discoloration in the polyethersiloxane presents a major challenge, particularly in those reactant systems, which result in SiOC-linked ABA-structured polyethersiloxanes and have unsaturated moieties (e.g., allyloxy end groups) in the polyether moieties. These special polyether siloxanes, with their sometimes excellent pigment affinities, are of outstanding importance as additives in dye and coating formulations.

As a comparative experiment (Example 4) shows, a non-inventive implementation of the trifluoromethanesulfonic a, w-diacetoxypolydimethylsiloxane can lead to strongly dark brown colored products.

Surprisingly, it has additionally been found that the polyethersiloxanes prepared according to the invention have excellent storage stability. As a criterion for evaluating the storage stability of the SiOC-linked polyether siloxanes prepared in the context of the inventive teaching, the viscosity is monitored as a function of time at constant storage temperature by sampling, since possible degradation and / or build-up processes are sensitively manifested herein.

According to the invention, condensation catalysts are preferably used. In particular, all Brönstedt acids, in this case preferably the simple mineral acids and methanesulfonic acid, phosphoric acid, phosphonic acids and / or acidic salt-like compounds such as triflate salts, In particular, bismuth triflate and / or all Lewis acidic compounds such as tin and organotin compounds, titanate esters, tetraalkoxy titanates, zinc acetylacetonate, zinc acetate and trispentafluorophenylborane are capable of catalyzing the reaction of the acetoxysiloxane with polyether monools. Very particular preference is given to using trichloroacetic acid as the condensation catalyst. The corresponding use of condensation catalysts, in particular trichloroacetic acid, corresponds to a particularly preferred embodiment of the invention.

Another object and another preferred embodiment of this invention is the salt-free exchange of acetoxy groups bound to linear siloxanes by polyetheroxy radicals by reacting the trifluoromethanesulfonic acid bearing acetoxy groups, linear siloxane in the presence of buffer mixtures and optionally an additional condensation catalyst and optionally in an inert Solvent brings together with the polyetherol with stirring to the reaction and then removed in the course of a distillation, the resulting acetic acid and residues used Acetanhydrids optionally together with portions of the solvent used. This corresponds to a preferred embodiment of the invention for the replacement of the siloxane-bound acetoxy groups by the reaction with polyether alcohols (see also Examples 2 and 3).

Preference is given to those solvents which are inert in the sense of the desired substitution reaction (exchange acetoxy vs. polyetheroxy radical) and preferably form a thermally separable azeotrope with the resulting acetic acid. This corresponds to a further preferred embodiment of the invention, wherein the use of an aromatic, preferably alkylaromatic solvent is preferred.

Among the acetic acid binary azeotroping solvents, toluene is most preferred. The use of toluene therefore corresponds to a preferred embodiment of the invention. The boiling points of toluene and acetic acid are given as 1.10.6 and 1.18.5 ° C, respectively, and the boiling point of the binary azeotrope as 105.4 ° C. The azeotrope has a composition of 72 weight percent toluene and 28 weight percent acetic acid (Source: Handbook of Chemistry and Physics, 58th Edition, page D2, CRC-Press (1977-1978), West Palm Beach). Usually, this can be used for this purpose, a technical toluene without further predrying, which has a water content of 0.03 percent by mass (water content determination according to the Karl Fischer method based on DIN 51777, DGF E-Ill 10 and DGF C-III 13a).

The thermal circling of the acetic acid accompanying the azeotrope formation ensures complete exchange of the acetoxy functions bound to the siloxane skeleton with polyetheroxy radicals and therefore corresponds to a particularly preferred embodiment of the invention.

In addition, the application of an auxiliary vacuum is very particularly preferred since it minimizes the thermal stress on the resulting SiOC-linked, linear polyethersiloxane (compare Examples 2 and 3). This corresponds to a further preferred embodiment of the invention.

Surprisingly, however, it was also found that the solvent-free transformation of trifluoromethanesulfonic acid linear, acetoxy-functional siloxanes to linear SiOC linked polyethersiloxanes very quickly (within 3 hours) and also at very moderate temperatures (T = 70 ° C) quantitatively successful (see Example 2 and 3).

If the replacement of the siloxane-bound acetoxy groups by the reaction with polyether monools is solvent-free, then there is accordingly a further preferred embodiment of the invention.

To introduce the acetoxy groups, trifluoromethanesulfonic acid is preferably used in concentrations of 0.1 to 0.3 percent by weight (w%) based on the total mass of the reaction mixture. This corresponds to a particularly preferred embodiment of the invention.

According to the invention, after the distillative separation and the acetic acid optionally present in the system and optionally both in the solvent-using and in the solvent-free cases, the SiOC-linked polyether siloxane remaining in the distillation bottoms is preferably added by adding an auxiliary base such as, for example Sodium carbonate and subsequent filtration completely free from traces of residual acid (see Examples 2 and 3). This corresponds to a further preferred embodiment of the invention

To ensure increased storage stability, the linear polyethersiloxanes prepared by the process according to the invention can also be mixed with small amounts of organic amines, such as N-methylmorpholine. This corresponds to a preferred embodiment of the invention.

In the concluding step of the process according to the invention, the replacement of the acetoxy groups by the reaction of the trifluoromethanesulfonic acid acetoxysiloxane with polyether monools is carried out.

In this case, the polyether monools which can be used according to the invention are preferably those of the formula (I)

A [-O- (CH ₂ -CHR'-O-) m- (CH ₂ -CH ₂ -O-) n- (CH ₂ -CH (CH ₃ ) -O-) oZ], (I)

With

A is a saturated or unsaturated organic radical having at least one carbon atom, preferably an organic radical of an organic starting compound having at least one carbon atom for preparing the compound, particularly preferably a linear or branched saturated or unsaturated hydrocarbon radical having 1-18 C atoms, preferably a methyl , Ethyl, propyl, butyl, vinyl or allyl group,

R 'independently of one another is a saturated alkyl group having 2-18 C atoms or an aromatic radical, or preferably an ethyl group or a phenyl radical,

Z is hydrogen,

m is 0 to 50, preferably 0 to 30, more preferably 0 to 20

n is 0 up to 250, preferably 3 up to 220, more preferably 5 up to 200 o is 0 to 250, preferably 3 to 220, more preferably 5 to 200, a is equal to 1

with the proviso that the sum of m, n and o is equal to or greater than 1. This corresponds to a preferred embodiment of the invention.

Preference is given to using compounds of the formula (I) which have exclusively hydrogen atoms, oxygen atoms and carbon atoms.

The index numbers reproduced here and the value ranges of the specified indices can be understood as mean values (weight average) of the possible statistical distribution of the actual structures present and / or their mixtures. This also applies to as such per se exactly reproduced structural formulas, such as for formula (I).

The units denoted by m, n and o can optionally be mixed randomly or else in blocks in the chain. Statistical distributions can be constructed block by block with an arbitrary number of blocks and an arbitrary sequence or a randomized distribution, they can also be of alternating construction or also form a gradient over the chain, in particular they can also form all mixed forms in which optionally groups of different Distributions can follow one another. Special designs may cause statistical distributions to be constrained by execution. For all areas that are not affected by the restriction, the statistical distribution does not change.

In the context of the present invention, the radical A is preferably understood as meaning radicals of substances which form the beginning of the compound of the formula (I) to be prepared, which is obtained by the addition of alkylene oxides. The starting compound is preferably selected from the group of alcohols, polyethers or phenols. The starting compound containing the group A is preferably a monohydric polyether alcohol and / or a monohydric alcohol, or any desired mixtures thereof.

The monomers used in the alkoxylation reaction are preferably ethylene oxide, propylene oxide, butylene oxide and / or styrene oxide, as well as any desired mixtures of these epoxides. The different monomers can be used in pure form or mixed. Also, the metered addition of another epoxide to an epoxide already present in the reaction mixture can be continuous over time so that an increasing concentration gradient of the continuously added epoxide is produced. The resulting polyoxyalkylenes are thus subject to a statistical distribution in the final product, with restrictions by the dosage can be determined. In the case mentioned here of the continuous addition of another epoxide to an epoxide already present in the reaction mixture, a structure gradient can then be expected over the chain length. The relationships between dosage and product structure are known in the art.

In the process according to the invention, the compounds of the formula (I) used are preferably those which have a weight average molecular weight of from 76 to 10,000 g / mol, preferably from 100 to 8,000 g / mol and more preferably from 200 to 6,000 g / mol. As compounds of the formula (I) it is possible with preference to use those compounds which are prepared from a compound of the formula (II)

A [-OH] a (II)

have emerged, wherein the radical A is derived from compounds selected from the group of monovalent monomeric, oligomeric or polymeric alcohols, phenols, carbohydrates or carbohydrate derivatives, particularly preferably those compounds are used in which the radical A of one or more alcohols deriving from the group of butanol, 1-hexenol, octanol, dodecanol, stearyl alcohol, vinyloxybutanol, 2-ethylhexanol, cyclohexanol, benzyl alcohol, allyl alcohol, vinyl alcohol, or naturally-based compounds bearing monovalent hydroxyl groups.

Particularly preferred compounds are those which are liquid at a pressure of 101325 Pa and a temperature of 23 ° C.

Compounds of the formula (I) which can be used according to the invention as polyetherois and processes for their preparation are described, for example, in US Pat. In EP0075703, US3775452 and EP1031603. Suitable methods are used e.g. basic catalysts such as e.g. alkali hydroxides and alkali methylates. Especially widespread and known for many years is the use of KOH. Typically, a low molecular weight, that is, having a molecular weight of less than 200 g / mol, hydroxy-functional starters such as butanol, allyl alcohol, propylene glycol in the presence of the alkaline catalyst with an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide or a mixture of different alkylene oxides a polyoxyalkylene polyether reacted. The strongly alkaline reaction conditions in this so-called living polymerization promote various side reactions. The compounds of formula (II) may also be prepared by double metal cyanide catalysis. Polyethers prepared by double metal cyanide catalysis generally have a particularly low level of unsaturated end groups of less than or equal to 0.02 meq / gram of polyether compound (meq / g), preferably less than or equal to 0.015 meq / g, more preferably less than or equal to 0.01 meq / g (method of determination ASTM D2849-69), contain significantly fewer monols and usually have a low polydispersity of less than 1.5. The polydispersity (PD) can be determined by a method known to the person skilled in the art by determining both the number average molecular weight (Mn) and the weight average molecular weight (Mw) by gel permeation chromatography (GPC). The polydispersity results as PD = Mw / Mn. The preparation of such polyethers z. For example, in US-A5158922 and EP-A0654302 described.

Regardless of the preparation route, preference is given to compounds of the formula (I) which preferably have a polydispersity Mw / Mn of from 1.0 to 1.5, preferably having a polydispersity of from 1.0 to 1.3.

Depending on the alkylene oxide terminus, the polyether monools to be used according to the invention may have a primary or secondary OH function. In view of the later achieved hydrolytic resistance of the SiOC-linked polyether siloxanes obtained, the use of such polyether monools which have a secondary alcohol function is preferred within the scope of the inventive teaching. The exchange according to the invention of the acetoxy groups bonded to the α, ω-diacetoxypolydimethylsiloxane by reaction with polyethermonools to form SiOC-linear polyethersiloxanes can be carried out in the presence of solvents or preferably without solvent by intimate mixing of the reactants with stirring at reaction temperatures of 20 ° C. to 90 ° C. be carried out at reaction temperatures of 30 ° C to 80 ° C. This corresponds to a preferred embodiment of the invention.

The molar ratio of the reactants is preferably such that at least 1 mol of OH functionality bound to the polyether per mole of acetoxy group of the α, ω-diacetoxy-polydimethylsiloxane, preferably 1 to 2 moles of OH functionality bonded to the polyether, more preferably 1, 1 to 1, 6 moles of polyether-bonded OH functionality, preferably 1, 1 to 1, 4 moles of polyether-bonded OH functionality per mole of acetoxy group of a, w-Diacetoxypolydimethylsiloxans used. This corresponds to a preferred embodiment of the invention.

The SiOC-linked, branched polyether siloxanes used in a large number of surface-active applications are frequently characterized as containing polyether radicals of different composition and / or molecular weight. Thus, it corresponds to a preferred embodiment of the method according to the invention to react the acetoxy-containing, equilibrated linear siloxane with a mixture of various types Polyetheroie. A person skilled in the art is familiar with the sometimes different reaction behavior of the polyetheroie employed, so that the aim is to induce a special interfacial activity, make some orienting hand tests with polyetherol mixtures and then evaluate these products in each case in terms of performance, in order to achieve an optimum result.

The replacement of the acetoxy groups by reaction with polyether alcohols is carried out according to the invention preferably in the course of 30 minutes to 8 hours. This corresponds to a preferred embodiment of the invention.

Another object of the invention is the use of this preparation, prepared by the novel process as described above, as a surfactant additive in non-corrosive cleaning solutions, as defoamers, as foam stabilizers, wetting agents, coating and leveling additives and as a demulsifier.

Examples

The following examples serve the skilled person alone to illustrate this invention and do not represent any limitation of the claimed subject matter. The determination of the water content according to the invention is carried out in principle by the Karl Fischer method based on DIN 51777, DGF E-Ill 10 and DGF C-III 13a. ²⁹ Si NMR spectroscopy was used in all examples for reaction tracking.

The ²⁹ Si NMR samples are used in this invention 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 is dissolved at 22 ° C in CDCl 3 and measured against tetramethylsilane (TMS) as an external standard [5 ( ²⁹ Si) = 0.0 ppm].

The GPC ^'s (gel permeation chromatography) are carried out using THF as the mobile phase on a column combination SDV 1000 / 10000A, length 65 cm, ID 0.80 at a temperature of 30 ° C on a SECcurity ² GPC System 1260 ( PSS Polymer Standards Service GmbH).

The gas chromatograms are fitted on a GC 7890B GC machine from Agilent Technologies with an HP-1 column; 30m x 0.32mm ID x 0.25pm dF (Agilent Technologies # 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.

As an indicator for the achievement of the equilibrium equilibrium, the total cyanogen 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-diisopropoxypolydimethylsiloxanes , The derivatization to the α, ω-diisopropoxypolydimethylsiloxanes 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 the gas chromatographic analysis (for the cleavage reaction see, inter alia, J. Pola et al., Collect. Czech Chem. Commun. 1974, 39 (5), 1 169-1 176, 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)).

The argentometric titration for the determination of the total chloride content in the ppm range is performed using a Metrohm Titroprocessor 736/751 equipped with a combined silver / metal electrode (eg Metrohm Part No. 6.0418.100) using a silver nitrate solution c (AgNO 3) = 0.01 mol / l (eg Fluka Fixanal Item No. 38310).

The polyether monools used have water contents of about 0.2 percent by mass and are used without further predrying.

In order to safeguard the storage stability, which is particularly important in terms of production logistics, the acetoxysiloxanes prepared according to the invention are not stored explicitly in glass bottles at 23 ° C. storage temperature for a period of 3 weeks unless they are explicitly described differently in the respective synthesis examples before they are combined with the polyether alcohols to form the corresponding SiOC-linked linear polydimethylsiloxane-polyoxyalkylene block copolymers or to the corresponding aw-Diisopropoxypolvdimethylsiloxanen be implemented. Example 1 (according to the invention)

Preparation of an acetoxy-terminated, linear polydimethylsiloxane

19.3 g (0.189 mol) of acetic anhydride together with 183.2 g (0.494 mol) of decamethylcyclopentasiloxane (Ds) are initially charged in a 500 ml four-necked flask with KPG stirrer, internal thermometer and attached reflux condenser with stirring and 0.12 ml) of trifluoromethanesulfonic acid (0.1% by mass, based on the overall batch) and heated rapidly to 150 ° C. The initially slightly cloudy reaction mixture is left under further stirring for 6 hours at this temperature.

After cooling of the approach, a colorless-clear, easily mobile liquid is isolated, the ²⁹ Si NMR spectrum of the presence of Si-acetoxy groups in a yield of about 80% based on the acetic anhydride assigned according to a, w-Diacetoxypolydimethylsiloxan with a middle Total chain length of about 16. The potentiometric argentometry shows a total chloride content of 2 ppm.

Example 2 (according to the invention)

Preparation of a SiOC-Linked, Linear Polydimethylsiloxane-Polyoxyalkylene Block Copolymer of the Structure Type ABA with Allyloxy Termini (Solvent-Free)

In a 500 ml four-necked flask with KPG stirrer, internal thermometer and attached reflux condenser, 104.0 g of a polyetherol containing allyl alcohol-initiated polypropyleneoxy (polyethyleneoxy) groups with 80% propylene oxide fraction of average molecular weight 757 g / mol (determined according to OH) Number) with stirring. Then, a buffer solution consisting of 0.32 g of sodium trichloroacetate (224% by weight excess based on the trifluoromethanesulfonic acid present in the acetoxysilane), 0.37 g of trichloroacetic acid (0.2% based on the reaction mixture consisting of polyetherol and acetoxysiloxane) dissolved in 5 g acetic acid added. Then, 80.0 g of an acetoxy-terminated, linear siloxane prepared according to Example 1 are added. The reaction mixture is heated with further stirring to 70 ° C and holds this reaction temperature for 3 hours.

The reflux condenser is replaced by a distillation bridge and the volatiles are distilled off at 70 ° C. and an applied auxiliary vacuum of <1 mbar.

After breaking the vacuum, the distillation bottom is treated with 3.68 g of sodium carbonate Na ₂ C 3 O in the heat and the batch is allowed to continue stirring at 70 ° C. for 2 hours. After cooling to 23 ° C, the solid with the aid of a filter press (filter disk Seitz K 300) separated.

A colorless, clear polyether siloxane whose associated ²⁹ Si NMR spectrum demonstrates the desired structure is isolated. Example 3 (according to the invention)

In a 500 ml four-necked flask with KPG stirrer, internal thermometer and attached reflux condenser, 104.0 g of a polyetherol containing allyl alcohol-initiated polypropyleneoxy (polyethyleneoxy) groups with 80% propylene oxide fraction of average molecular weight 757 g / mol (determined according to OH) Number) with stirring. Then a buffer solution consisting of 0.16 g of sodium acetate (266% by weight excess based on the trifluoromethanesulfonic acid present in the acetoxysilane), 0.37 g of trichloroacetic acid (0.2% based on the reaction mixture consisting of polyetherol and acetoxysiloxane) dissolved in 5 g acetic acid added. Then, 80.0 g of an acetoxy-terminated, linear siloxane prepared according to Example 1 are added. The reaction mixture is heated with further stirring to 70 ° C and holds this reaction temperature for 3 hours.

A colorless, clear polyether siloxane whose associated ²⁹ Si NMR spectrum demonstrates the desired structure is isolated.

Example 4 (not according to the invention)

In a 500 ml four-necked flask with KPG stirrer, internal thermometer and attached reflux condenser, 104.0 g of a polyetherol containing allyl alcohol-initiated polypropyleneoxy (polyethyleneoxy) groups with 80% propylene oxide fraction of average molecular weight 757 g / mol (determined according to OH) Number) with stirring. Then, 80.0 g of an acetoxy-terminated, linear siloxane prepared according to Example 1 are added. The reaction mixture is heated with further stirring to 70 ° C and holds this reaction temperature for 3 hours. During the heating phase, the approach already undergoes a significant brown-black discoloration.

The reflux condenser is replaced by a distillation bridge and the volatiles are distilled off at 70 ° C. and an applied auxiliary vacuum of <1 mbar. After breaking the vacuum, the distillation bottom is treated with 3.68 g of sodium carbonate Na ₂ C 3 O in the heat and the batch is allowed to continue stirring at 70 ° C. for 2 hours. After cooling to 23 ° C, the solid with the aid of a filter press (filter disk Seitz K 300) separated.

A strong dark brown colored, clear polyethersiloxane whose associated ²⁹ Si NMR spectrum demonstrates the desired structure is isolated.

Example 5 (according to the invention)

Preparation of an acetoxy-terminated, linear polydimethylsiloxane

In a 1000 ml four-necked flask equipped with KPG stirrer, internal thermometer and attached reflux condenser, 77.3 g (0.757 mol) of acetic anhydride together with 732.8 g (1.98 mol) of decamethylcyclopentasiloxane (Ds) and 12.2 g of acetic acid (1 , 5 wt .-% based on the total mass of the reactants) with stirring and with 1.62 g (0.88 ml) of trifluoromethanesulfonic acid (0.2 percent by weight based on the total amount) and heated rapidly to 150 ° C. The initially slightly cloudy reaction mixture is left under further stirring for 6 hours at this temperature.

After cooling of the approach, a colorless-clear, easily movable liquid is isolated, the ²⁹ Si-NMR spectrum of the presence of Si-acetoxy groups in a yield of about 93% based on the acetic anhydride assigned according to a, w-Diacetoxypolydimethylsiloxan with a middle Total chain length of approx. 14.

Conversion of the α.w-Diacetoxypolvdimethylsiloxans in the corresponding a.w-diisopropoxy-polvdimethylsiloxan for analytical characterization

Immediately after the synthesis, 50.0 g of this trifluoromethanesulfonic, equilibrated a, w-diacetoxypolydimethylsiloxane in a 250 ml four-necked round bottom flask equipped with KPG stirrer, internal thermometer and attached reflux condenser with 1 1, 3 g of a molecular sieve dried isopropanol with stirring mixed at 22 ° C. The reaction mixture is then charged by introducing gaseous ammonia (NH3) to the alkaline reaction (wet universal indicator paper) and then stirred for 45 minutes at this temperature. The precipitated salts are separated by means of a pleated filter.

A colorless, clear liquid is isolated whose accompanying ²⁹ Si NMR spectrum demonstrates the quantitative conversion of the α, ω-diacetoxypolydimethylsiloxane to an α, ω-diisopropoxypolydimethylsiloxane.

An aliquot of this a, w-Diisopropoxypolydimethylsiloxans is removed and analyzed by gas chromatography. The gas chromatogram has the following contents (in percentage by mass):

Taking into account the Isopropanolüberschusses the contents of siloxane (D _4, D s and D _Ö) are in this case calculated based solely on the siloxane.

Example 6 (according to the invention)

Preparation of an acetoxy-terminated, linear polydimethylsiloxane

In a 1000 ml four-necked flask equipped with KPG stirrer, internal thermometer and attached reflux condenser, 77.3 g (0.757 mol) of acetic anhydride together with 732.8 g (1.98 mol) of decamethylcyclopentasiloxane (Ds) and 24.3 g of acetic acid (3 , 0 wt .-% based on the total mass of the reactants) with stirring and with 1.62 g (0.88 ml) of trifluoromethanesulfonic acid (0.2 percent by weight based on the total amount) and heated rapidly to 150 ° C. The initially slightly cloudy reaction mixture is left under further stirring for 4 hours at this temperature.

Claims

claims

1. A process for preparing trifluoromethanesulfonsaurer equilibrated a, w-Diacetoxypolydimethylsiloxane, characterized in that cyclic siloxanes, in particular comprising D ₄ and / or Ds, using trifluoromethanesulfonic acid as the catalyst with acetic anhydride, preferably with the addition of acetic acid, is reacted.

2. The method according to claim 1, characterized in that one uses the trifluoromethanesulfonic acid in amounts of 0.1 to 0.3 percent by mass, based on the consisting of acetic anhydride and cyclic siloxanes reaction matrix.

3. The method according to claim 1 and 2, characterized in that the reaction in

Temperature range of 140 to 160 ° C and carried out in a period of 4 to 8 hours.

4. The method according to at least one of claims 1 to 3, characterized in that one acetic acid in amounts of 0.4 to 3.5 weight percent, preferably 0.5 to 3 weight percent, preferably 0.8 to 1, 8 weight percent, more preferably in amounts of 1, 0 to 1, 5 weight percent based on the reaction matrix consisting of acetic anhydride and cyclic siloxanes added.

5. Trifluoromethanesulfonic acid, equilibrated a, w-Diacetoxypolydimethylsiloxane the general formula

with R = methyl,

the average chain length determined by ²⁹ Si-NMR spectroscopy is 0 <X <250, preferably 5 <X <100, particularly preferably 10 <X <30

have as well

0.1 to 0.3 mass percent trifluoromethanesulfonic acid,

and 5 to 43% by volume, preferably 11 to 25% by volume, of free acetic anhydride, based on the

a, w-diacetoxypolydimethylsiloxane chemically bonded acetic anhydride equivalent,

contain.

6. trifluoromethanesulfonic acid equilibrated a, w-Diacetoxypolydimethylsiloxane according to claim 5, characterized in that they have a mean determined by ²⁹ Si NMR spectroscopy chain length of 10 <X <30, in particular of 10 <X <20.

7. trifluoromethanesulfonic acid equilibrated a, w-Diacetoxypolydimethylsiloxane according to claim 5 or 6, obtainable according to claim 1 to 4.

8. A process for the preparation of SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA, characterized in that trifluoromethanesulfonsaures, equilibrated a, w-Diacetoxypolydimethylsiloxan, preferably according to one of claims 5 to 7, with polyether monools in the presence of buffer mixtures and optionally an additional condensation catalyst and optionally in the presence of an inert solvent.

9. The method according to claim 8, characterized in that the amount of the base used to charge the polyether monool in the buffer mixture is such that it is at least the stoichiometric equivalent, preferably at least twice the stoichiometric equivalent of the a, w-Diacetoxypolydimethylsiloxan trifluoromethanesulfonic acid equivalent.

10. The method according to claim 8 or 9, characterized in that the polyether monool optionally initially mixed in the presence of an inert solvent with buffer mixtures and optionally an additional a, w-Diacetoxypolydimethylsiloxan, preferably according to one of claims 5 to 7,

and then thermally separating the liberated acetic acid optionally present in the system together with the solvent, using an azeotrope-forming solvent, and neutralizing, filtering and possibly end-stabilizing the obtained SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymer by adding an auxiliary base.

1 1. The method according to any one of claims 8 to 10, characterized in that a condensation catalyst for the reaction of the equilibrated a, w-Diacetoxypolydimethylsiloxans is used with polyether monools,

wherein as condensation catalyst Brönstedt acids, in this case preferably the simple mineral acids and methanesulfonic acid, phosphoric acid, phosphonic acids and / or acidic salt-like compounds such as triflate salts, in particular bismuth triflate and / or Lewis acidic compounds such as tin and organotin compounds, titanate esters, tetraalkoxytitanates, zinc acetylacetonate, zinc acetate , Trispentafluorphenylboran and most preferably trichloroacetic acid are used, wherein the condensation catalyst, in particular the trichloroacetic acid, in the range of 0.1 to 0.7 percent by mass, preferably between 0.2 to 0.5 mass percent based on the total amount of the SiOC linkage reaction provided reactants, namely a, w-diacetoxypolydimethylsiloxane and polyether monool, is used.

12. The method according to any one of claims 8 to 1 1, characterized in that the buffer mixtures used contain at least portions of the condensation catalyst and in this case particularly preferably the condensation catalyst in the form of a salt.

13. The method according to any one of claims 8 to 12, characterized in that the buffer mixtures comprise sodium trichloroacetate and acetic acid or sodium acetate and acetic acid.

14. The method according to claim 8 to 13, characterized in that the solvent is aromatic, preferably alkylaromatic solvents, preferably those which form a thermally separable azeotrope with acetic acid and most preferably toluene are used,

or

that works solvent-free.

15. The method according to any one of claims 8 to 14, characterized in that the replacement of the a, w-Diacetoxypolydimethylsiloxan bound acetoxy groups by reaction with polyether monools linked to SiOC, linear polyether siloxanes in the presence of solvents or preferably without solvent by intimate mixing of the reactants under Stirring at reaction temperatures of 20 ° C to 90 ° C, preferably at reaction temperatures of 30 ° C to 80 ° C and preferably in the course of 30 minutes to 8 hours,

and / or, preferably and,

that the separation of the liberated in the reaction between a, w-Diacetoxypolydimethylsiloxan and polyether monools and optionally present in the system acetic acid preferably under application of an auxiliary vacuum by distillation at temperatures between 60 ° C and 90 ° C.

16. The method according to claim 8 to 15, characterized in that the molar ratio of the reactants is so dimensioned that at least 1 mole of polyether-bound OH functionality per mole of acetoxy group of a, w-diacetoxy-polydimethylsiloxans, preferably 1 to 2 mol polyether-bonded OH functionality, particularly preferably 1, 1 to 1, 6 moles of polyether-bonded OH functionality, preferably 1, 1 to 1, 4 moles of polyether-bound OH functionality per mole of acetoxy group of the a, w-diacetoxy-polydimethylsiloxans starts.

17. Linear SiOC-linked polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA, obtainable according to one of claims 8 to 16, and their use as surfactant additive in non-corrosive cleaning solutions, as defoamers, as foam stabilizers, wetting agents, coating and leveling additives and as Dismulgatoren.