Process for producing non-cyclic alkoxy-functional polysiloxanes

Abstract

A reaction product containing a non-cyclic alkoxy-functional polysiloxane is produced by heating a reaction system, which contains a cyclic polyorganosiloxane of the formula [(R.sup.1.sub.2SiO).sub.2/2].sub.n, where the subscript n is an integer of at least 4 and each R.sup.1 is an alkyl group or aryl group; a silane of the formula R.sup.2.sub.(4−m)Si(OR.sup.3).sub.m, where the subscript m is an integer from 1 to 4, each R.sup.2 independently is an alkyl group or aryl group, a hydrocarbyl group or a halogenated hydrocarbyl group and each R.sup.3 independently is an alkyl group; and a catalyst system comprising a metal trifluoromethanesulfonate of the formula [M].sup.+[CF.sub.3SO.sub.3].sup.−, where M is a metal atom selected from sodium (Na) and potassium (K), and a Brønsted acid, wherein Brønsted acids having a pKa≤3.0, preferably having a pKa≤2.0, particularly preferably having a pKa≤−0.0 are used.

Claims

1. A process for producing a reaction product comprising a non-cyclic alkoxy-functional polysiloxane, the process comprising: heating a reaction system comprising: (A) a cyclic polyorganosiloxane of formul a [(R.sup.1.sub.2SiO).sub.2/2].sub.n, wherein n is an integer of at least 4 and each R.sup.1 is an alkyl group or aryl group; (B) a silane of formula R.sup.2.sub.(4-m)Si(OR.sup.3).sub.m, wherein m is an integer from 1 to 4, each R.sup.2 independently is selected from the group consisting of an alkyl group, aryl group, a hydrocarhyl group, and a halogenated hydrocarbyl group, and each R.sup.3 independently is an alkyl group; and (C) a catalyst system comprising: a metal trifluoromethanesulfonate of formula [M].sup.+[CF.sub.3SO.sub.3].sup.−, wherein M is a metal atom selected from sodium (Na) and potassium (K), and a Brønsted acid, wherein the Bøonsted acid has a pKa≤3.0.

2. The process according to claim 1, wherein a molar ratio of the Brønsted acid to the metal trifluoromethanesulfonate is in a range from 1:10 to 10:1.

3. The process according to claim 1, wherein the Brønsted acid is selected from the group consisting of carboxylic acids, sulfonic acids, and mineral acids.

4. The process according to claim 1, wherein the silane is selected from the group consisting of a ditnethyldialkoxysilane selected from the group consisting of diethoxydimethylsilane and dimethoxydimethylsilane, a methyltrialkoxysilane selected from the group consisting of triethoxymethylsilane, and trimethoxymethylsilane, and a tetraalkoxysilane selected from the group consisting of tetraethoxysilane and tetramethoxysilane.

5. The process according to claim 1, wherein the cyclic polyorganosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane (D.sub.4), decamethylcyclopentasiloxane (D.sub.5), dodecamethylcyclohexasiloxane (D.sub.6), and a mixture thereof.

6. The process according to claim 1, wherein the cyclic polyorganosiloxane is a cyclic branched polyorganosiloxane of D/T type which is, i) mixtures of cyclic branched siloxanes of the D/T type which comprises siloxanes having D and T units and whose cumulative proportion of D and T units present in a siloxane matrix and having Si-alkoxy and/or SiOH groups, determinable by .sup.29Si NMR spectroscopy, is ≤2 mole per cent, or ii) mixtures of cyclic branched siloxanes having D and T units whose cumulative proportion of D and T units present in a siloxane matrix and having Si-alkoxy and/or SiOH groups, determinable by .sup.29Si NMR spectroscopy, is greater than 2 and less than 10 mole per cent.

7. The process according to claim 1, wherein the heating takes place at a temperature of 40° C. to 180° C., for a time which suffices for the formation of the non-cyclic alkoxy-functional siloxane.

8. The process according to claim 1, wherein (A) and (B) are used in amounts such that a molar ratio of (A)/(B) is at least 1:1.

9. The process according to claim 1, wherein (C) is present in an amount of 0.1 to 5 wt. %, based on combined weights of the (A), (B), and (C).

10. The process according to claim 1, wherein water is not added to the reaction system.

11. The process according to claim 1, wherein the Bronsted acid has a pKa≤0.0.

12. The process according to claim 2, wherein the molar ratio of the Bronsted acid to the metal trifluoromethanesulfonate is in a range from 1:2 to 2:1.

13. The process according to claim 3, wherein the Bronsted acid is selected from the group consisting of trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesuffonic acid, hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid.

14. The process according to claim 5, wherein the cyclic polyorganosiloxane is D.sub.5.

15. The process according to claim 6, wherein, for the mixture of i), the cumulative proportion of D and T units is less than 1 mole per cent, and wherein the mixture of i) comprises at east 5 per cent by weight of a siloxane cycle selected from the group consisting of D.sub.4, D.sub.5, and a mixture thereof.

16. The process according to claim 8, wherein the molar ratio of (A)/(B) is at least 2:1.

17. The process according to claim 9, wherein (C) is present in an amount of 0.5 to 1 wt. %, based on the combined weights of (A), (B), and (C).

Description

BRIEF DESCRIPTION OF DRAWING

(1) The FIGURE shows a .sup.29Si NMR spectrum. The signal at −13 ppm can be assigned to the ethoxy groups. The polysiloxane chain is recognised at −22 ppm.

DETAILED DESCRIPTION OF THE INVENTION

(2) In this connection, it has been found in accordance with the invention, and completely surprisingly, that a process for producing a reaction product containing a non-cyclic alkoxy-functional polysiloxane by means of heating a reaction system comprising: (A) a cyclic polyorganosiloxane of the formula [(R.sup.1.sub.2SiO).sub.2/2].sub.n, where the subscript n is an integer of at least 4 and each R.sup.1 is an alkyl group or aryl group; (B) a silane of the formula R.sup.2.sub.(4−m)Si(OR.sup.3).sub.m, where the subscript m is an integer from 1 to 4, each R.sup.2 independently is an alkyl group or aryl group, a hydrocarbyl group or a halogenated hydrocarbyl group and each R.sup.3 independently is an alkyl group; and (C) a catalyst system comprising a metal trifluoromethanesulfonate of the formula [M].sup.+[CF.sub.3SO.sub.3].sup.−, where M is a metal atom selected from sodium (Na) and potassium (K), and a Brønsted acid,
wherein Brønsted acids having a pKa≤3.0, preferably having a pKa≤2.0, particularly preferably having a pKa≤−0.0 are used,
achieves the object in an outstanding manner.

(3) It was completely surprising that the acid-catalysed ring opening of the cyclic polyorganosiloxane by means of the inventive catalyst system comprising a metal trifluoromethanesulfonate of the formula [M].sup.+[CF.sub.3SO.sub.3].sup.−, where M is a metal atom selected from sodium (Na) and potassium (K), and a Brønsted acid was made possible at all.

(4) Trifluoromethanesulfonate salts, metal trifluoromethanesulfonates, triflates, metal triflates are understood here to be synonyms.

(5) The molar ratio of Brønsted acid used to metal trifluoromethanesulfonate is preferably in the range from 1:10 to 10:1, preferably from 1:5 to 5:1, particularly preferably from 1:2 to 2:1.

(6) Preferred co-catalysts are Brønsted acids. Examples of suitable Brønsted acids are carboxylic acids such as for example trifluoroacetic acid, sulfonic acids such as for example methanesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, mineral acids such as for example hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.

(7) The Brønsted acid that is particularly preferably to be used according to the invention is a methanesulfonic acid, sulfuric acid, phosphoric acid, trifluoroacetic acid and p-toluenesulfonic acid.

(8) The inventors have found that an acid-catalysed ring opening of the cyclic polyorganosiloxane using only Na triflates or K triflates or only methanesulfonic acid does not succeed, however a mixture of Na triflates or K triflates and methanesulfonic acids does. The advantage is thus that corrosive catalysts such as Al triflates or iron triflates can be dispensed with. Furthermore, the use of heavy metal-containing catalysts such as gallium triflates, scandium trifiates, chromium triflates is a further advantageous aspect of the invention.

(9) The silanes are preferably dimethyldialkoxysilanes (such as e.g. diethoxydimethylsilane and dimethoxydimethylsilane), methyltrialkoxysilanes (such as e.g. triethoxymethylsilane and trimethoxymethylsilane), and tetraalkoxysilanes (tetraethoxysilane and tetramethoxysilane).

(10) If within the context of the invention cyclic polyorganosiloxanes are used, in particular encompassing D.sub.3 (hexamethylcyclotrisiloxane), (octamethylcyclotetrasiloxane), D.sub.5 (decamethylcyclopentasiloxane) and/or D.sub.6 (dodecamethylcyclohexasiloxane), where D.sub.4 and/or D.sub.5 are particularly preferred, and D.sub.5 is most preferred, this is a further preferred embodiment of the invention.

(11) If within the context of the invention cyclic polyorganosiloxanes, in particular cyclic branched siloxanes of the DT type are used, these are preferably i. mixtures of cyclic branched siloxanes of the D/T type which (preferably exclusively) consist of siloxanes having D and T units and whose cumulative proportion of D and T units present in the siloxane matrix and having Si-alkoxy and/or SiOH groups, determinable by .sup.29Si NMR spectroscopy, is ≤2 mole percent, preferably less than 1 mole percent, and which preferably contain at least 5 percent by weight of siloxane cycles, such as preferably octamethylcyclotetrasiloxane (D.sub.4), decamethylcyclopentasiloxane (D.sub.5) and/or mixtures of these or else ii. mixtures of cyclic branched siloxanes having (preferably exclusively) D and T units whose cumulative proportion of D and T units present in the siloxane matrix and having Si-alkoxy and/or SiOH groups, determinable by .sup.29Si NMR spectroscopy, is greater than 2 and less than 10 mole percent,
this is a further preferred embodiment of the invention.

(12) According to a preferred embodiment of the invention, the heating takes place at a temperature of 40° C. to 180° C., particularly preferably of 80° C. to 150° C., for a time which suffices for the formation of the non-cyclic alkoxy-functional siloxane.

(13) The constituents (A) and (B) are preferably used in amounts such that the molar ratio of (A)/(B) is at least 1:1, preferably at least 2:1.

(14) The process according to the invention is characterized in that the constituent (C) is present preferably in an amount of 0.1 mol % to 5 mol %, preferably 0.2 mol % to 1 mol % and particularly preferably 0.5 mol % to 1 mol %. based on the combined weights of the constituents (A), (B) and (C).

(15) In terms of process engineering and economics, it is not preferable to add greater amounts of metal trffluoromethanesuffonates and Brønsted acids in the inventive reaction system, since these may also have to be removed again at the latest during the further processing of the alkoxy-functional siloxane obtained.

(16) In another preferred embodiment, no addition of water is required.

(17) The invention further provides for the use of alkoxy-functional siloxanes, produced using a reaction system, as described above, for the production of polyethersiloxanes, especially for the production of polyurethane foam stabilizers, defoamers, especially diesel defoamers, deaerating agents, wetting agents, paint additives, levelling additives and dispersing additives and/or demulsifiers, hydrophobizing agents.

(18) It is also conceivable to use polyethersiloxanes produced in this manner, as described above, for the production of polymer dispersions; for the production of adhesives or sealants; for the surface treatment of fibres, particles or fabrics, especially for the finishing or impregnation of textiles, for the production of paper towels, in the coating of fillers; for the production of cleaning and care formulations for the household or for industrial purposes, especially for the production of fabric softeners; for the production of cosmetic, pharmaceutical and dermatological compositions, especially cosmetic cleansing and care formulations, hair treatment agents and hair after treatment agents; for the cleaning and care of hard surfaces; as a processing aid in the extrusion of thermoplastics; for the production of thermoplastic shaped bodies; as adjuvant in crop protection; for the production of construction material compositions.

EXAMPLES

(19) The following examples serve only to explain this invention for those skilled in the art and do not constitute any restriction whatsoever of the claimed subject matter. Determination of the water contents is performed in principle by the Karl Fischer method based on DIN 51777, DGF E-III 10 and DGF C-III 13a. .sup.29Si NMR spectroscopy was used for reaction monitoring in all examples.

(20) In the context of this invention, the .sup.29Si NMR samples are analysed at a measurement frequency of 79.49 MHz in a Bruker Avance III spectrometer equipped with a 287430 probe head with gap width of 10 mm, dissolved at 22° C. in CDCl3 and measured against a tetramethylsilane (TMS) external standard [δ(.sup.29Si)=0.0 ppm].

(21) GPCs (gel permeation chromatography) are recorded using THF as the mobile phase on an SDV 1000/10000A column combination having a length of 65 cm, ID 0.80, at a temperature of 30° C. using a SECcurity.sup.2 GPC System 1260 (PSS Polymer Standards Service GmbH).

(22) The gas chromatograms are recorded on a GC instrument of the GC 7890B type from Agilent Technologies, equipped with a column of the HP-1 type; 30 m×0.32 mm ID×0.25 μm dF (Agilent Technologies no. 19091Z-413E) and hydrogen as carrier gas, with the following parameters: Detector: FID; 310° C. Injector: split; 290° C. Mode: constant flow, 2 ml/min Temperature programme: 60° C. at 8° C./min-150° C. at 40° C./min-300° C. 10 min.

(23) Unless stated otherwise, all figures are to be understood to be weight percentages.

I. Process According to the Invention for Producing a Non-Cyclic Alkoxy-Functional Polysiloxane

Example 1A

(24) A 500 ml four-neck round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser on top was initially charged with 327.2 g (4.4 mol of D units) of a D4/D5 cycle mixture available from Dow with 72.8 g (0.5 mol) of diethoxydimethylsilane (Dynasylan 9811, Evonik) while stirring at 23° C. In a second step, 0.8 g of potassium trifiates and 0.8 g of methanesulfonic acid were added sequentially to the reaction mixture. The mixture was subsequently heated to 140° C. and held at reaction temperature for 6 hours. After the reaction time, the reaction mixture was cooled down to 23° C. Cooling of the reaction mixture afforded a clear orange α-ω diethoxypolysiloxane. A clear terminal α-ω diethoxypolysiloxane is therefore obtained, the target structure of which is confirmed by the accompanying .sup.29Si NMR spectroscopy. The .sup.29Si NMR spectroscopy likewise assures that no contents whatsoever of SiOH groups are present, within the scope of measurement accuracy.

Example 1B

(25) A 500 ml four-neck round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser on top was initially charged with 327.2 g (4.4 mol of D units) of a D4/D5 cycle mixture available from Dow with 72.8 g (0.5 mol) of diethoxydimethylsilane (Dynasylan 9811, Evonik) while stirring at 23° C. In a second step, 0.8 g of potassium triflates, 0.8 g of methanesulfonic acid, and 0.2 g of water were added sequentially to the reaction mixture. The mixture was subsequently heated to 140° C. and held at reaction temperature for 6 hours. After the reaction time, the reaction mixture was cooled down to 23° C. Cooling of the reaction mixture afforded a clear yellow α-ω diethoxypolysiloxane.

(26) A clear terminal α-ω diethoxypolysiloxane is therefore obtained, the target structure of which is confirmed by the accompanying .sup.29Si NMR spectroscopy. The .sup.29Si NMR spectroscopy likewise assures that no contents whatsoever of SiOH groups are present, within the scope of measurement accuracy.

Example 1C

(27) A 500 ml four-neck round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser on top was initially charged with 327.2 g (4.4 mol of D units) of a D4/D5 cycle mixture available from Dow with 718 g (0.5 mol) of diethoxydimethylsilane (Dynasylan 9811, Evonik) while stirring at 23° C. In a second step, 0.8 g of sodium triflates and 0.8 g of methanesulfonic acid were added sequentially to the reaction mixture. The mixture was subsequently heated to 140° C. and held at reaction temperature for 6 hours. After the reaction time, the reaction mixture was cooled down to 23° C. Cooling of the reaction mixture afforded a clear colourless α-ω diethoxypolysiloxane. A clear terminal α-ω diethoxypolysiloxane is therefore obtained, the target structure of which is confirmed by the accompanying .sup.29Si NMR spectroscopy. The .sup.29Si NMR spectroscopy likewise assures that no contents whatsoever of SiOH groups are present, within the scope of measurement accuracy. (FIGURE)

(28) FIGURE: In the .sup.29Si NMR spectrum, the signal at −13 ppm can be assigned to the ethoxy groups. The polysiloxane chain is recognised at −22 ppm.

Example 1.D

(29) A 500 ml four-neck round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser on top was initially charged with 327.2 g (4.4 mol of D units) of a D4/D5 cycle mixture available from Dow with 72.8 g (0.5 mol) of diethoxydimethylsilane (Dynasylan 9811, Evonik) while stirring at 23° C. In a second step, 0.8 g of sodium triflates, 0.8 g of methanesulfonic acid, and 0.2 g of water were added sequentially to the reaction mixture. The mixture was subsequently heated to 140° C. and held at reaction temperature for 6 hours. After the reaction time, the reaction mixture was cooled down to 23° C. Cooling of the reaction mixture afforded a clear yellow α-ω diethoxypolysiloxane.

(30) A clear terminal α-ω diethoxypolysiloxane is therefore obtained, the target structure of which is confirmed by the accompanying .sup.29Si NMR spectroscopy. The .sup.29Si NMR spectroscopy likewise assures that no contents whatsoever of SiOH groups are present, within the scope of measurement accuracy.

II. Process for Producing a Non-Cyclic Alkoxy-Functional Siloxane Using Na Triflates or K Triflates

Example 2A

(31) A 500 ml four-neck round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser on top was initially charged with 327.2 g (4.4 mol of D units) of a D4/D5 cycle mixture available from Dow with 718 g (0.5 mol) of diethoxydimethylsilane (Dynasylan 9811, Evonik) while stirring at 23° C. In a second step, 0.8 g of potassium triflate was added to the reaction mixture. The mixture was subsequently heated to 140° C. and held at reaction temperature for 6 hours. After the reaction time, the reaction mixture was cooled down to 23° C. Cooling of the reaction mixture afforded a clear yellow mixture of D4/D5 and diethoxydimethylsilane.

(32) A terminal α-ω diethoxypolysiloxane is not obtained, evidence of which is provided by the accompanying .sup.29Si NMR spectroscopy.

Example 2B

(33) A 500 ml four-neck round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser on top was initially charged with 327.2 g (4.4 mol of D units) of a D4/D5 cycle mixture available from Dow with 72.8 g (0.5 mol) of diethoxydimethylsilane Dynasylan 9811, Evonik) while stirring at 23° C. In a second step, 0.8 g of sodium triflate was added to the reaction mixture. The mixture was subsequently heated to 140° C. and held at reaction temperature for 6 hours. After the reaction time, the reaction mixture was cooled down to 23° C. Cooling of the reaction mixture afforded a clear yellow mixture of D4/D5 and diethoxydimethylsilane.

(34) A terminal α-ω diethoxypolysiloxane is not obtained, evidence of which is provided by the accompanying .sup.29Si NMR spectroscopy.

III. Process for Producing a Non-Cyclic Alkoxy-Functional Siloxane Using MSA

Example 3A

(35) A 500 ml four-neck round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser on top was initially charged with 327.2 g (4.4 mol of D units) of a D4/D5 cycle mixture available from Dow with 72.8 g (0.5 mol) of diethoxydimethylsilane (Dynasylan 9811, Evonik) while stirring at 23° C. In a second step, 0.8 g of methanesulfonic acid was added to the reaction mixture. The mixture was subsequently heated to 140° C. and held at reaction temperature for 6 hours. After the reaction time, the reaction mixture was cooled down to 23° C. Cooling of the reaction mixture afforded a clear yellow mixture of D4/D5 and diethoxydimethylsilane.

(36) A terminal α-ω diethoxypolysiloxane is not obtained, evidence of which is provided by the accompanying .sup.29Si NMR spectroscopy.

Example 3B

(37) A 500 ml four-neck round-bottom flask equipped with a precision glass stirrer, an internal thermometer, and a reflux condenser on top was initially charged with 327.2 g (4.4 mol of D units) of a D4/D5 cycle mixture available from Dow with 72.8 g (0.5 mol) of diethoxydimethylsilane (Dynasylan 9811, Evonik) while stirring at 23° C. In a second step, 0.8 g of methanesulfonic acid, and 0.2 g of water were added sequentially to the reaction mixture. The mixture was subsequently heated to 140° C. and held at reaction temperature for 6 hours, After the reaction time, the reaction mixture was cooled down to 23° C. Cooling of the reaction mixture afforded a clear yellow mixture of D4/D5 and diethoxydimethylsilane. A terminal α-ω diethoxypolysiloxane is not obtained, evidence of which is provided by the accompanying .sup.29Si NMR spectroscopy.