Mixtures of cyclic branched siloxanes of the D/T type and conversion products thereof

Abstract

Mixtures of cyclic branched siloxanes having exclusively D and T units and having no functional groups, with the proviso that the cumulative proportion of the D and T units having Si-alkoxy and/or SiOH groups that are present in the siloxane matrix, determinable by .sup.29Si NMR spectroscopy, is 2 mole percent, are described, as are branched organo-modified siloxanes obtainable therefrom.

Claims

1. A mixture of cyclic branched siloxanes having exclusively D and T units and having no functional groups, wherein the cumulative proportion of the D and T units having Si-alkoxy and/or SiOH groups that are present in the siloxane matrix is determinable by .sup.29Si NMR spectroscopy, is 2 mole percent, based on the totality of silicon detected by spectroscopy.

2. The mixture of cyclic branched siloxanes having exclusively D and T units according to claim 1, wherein the branching T unit derives from alkyltrialkoxysilanes and/or phenyltrialkoxysilanes.

3. The mixture of cyclic branched siloxanes having exclusively D and T units according to claim 2, wherein the molar mass ratio of the mixture Mw/Mn is in the range of 2<Mw/Mn<50.

4. The mixture of cyclic branched siloxanes having exclusively D and T units according to claim 1, wherein the branching T unit derives from methyltriethoxysilane.

5. The mixture of cyclic branched siloxanes having exclusively D and T units according to claim 4, wherein the molar mass ratio of the mixture Mw/Mn is in the range of 2<Mw/Mn<50.

6. The mixture of cyclic branched siloxanes having exclusively D and T units according to claim 1, wherein the ratio of D to T units is between 6:1 and 4:1.

7. The mixture of cyclic branched siloxanes having exclusively D and T units according to claim 6, wherein the molar mass ratio of the mixture Mw/Mn is in the range of 2<Mw/Mn<50.

8. A mixture of cyclic branched siloxanes having exclusively D and T units and having no functional groups, wherein the cumulative proportion of the D and T units having Si-alkoxy and/or SiOH groups that are present in the siloxane matrix; determinable by .sup.29Si NMR spectroscopy, is 2 mole percent, wherein the ratio of D to T units is between 10:1 and 3:1.

9. The mixture of cyclic branched siloxanes having exclusively D and T units according to claim 8, wherein the molar mass ratio of the mixture Mw/Mn is in the range of 2<Mw/Mn<50.

10. The mixture of cyclic branched siloxanes having exclusively D and T units according to claim 8, wherein the molar mass ratio of the mixture Mw/Mn is in the range of 2<Mw/Mn<50.

Description

EXAMPLES

(1) 1) Preparation of a Cyclic Branched Siloxane Having a Target D/T Ratio of 8:1 (Inventive)

(2) In a 500 ml four-neck round-bottom flask with a precision glass stirrer and a reflux condenser on top, 40.5 g (0.227 mol) of methyltriethoxysilane are heated to 60 C. together with 134.5 g (0.363 mol) of decamethylcyclopentasiloxane in 200 ml of toluene while stirring, 0.375 g of trifluoromethanesulfonic acid is added and the mixture is equilibrated for 4 hours. Then 12.3 g of water and 3.1 g of ethanol are added and the mixture is heated to reflux temperature at about 80 C. for a further 4 hours. The reflux condenser is exchanged for a distillation system, and the constituents that are volatile up to 100 C. are distilled off within the next hour. Then the distillation system is replaced by the reflux condenser, 6.15 g of water and 1.5 g of ethanol are added to the mixture and the mixture is left to boil for a further hour. The reflux condenser is then replaced once again by a distillation system, and the constituents that are volatile up to 100 C. are removed over the course of the next hour. The mixture is cooled to 60 C. and then 4 m % of sodium hydrogencarbonate is added, the mixture is stirred for half an hour, then the salt is separated from the liquid phase with the aid of a fluted filter. The volatiles are distilled off at 70 C. and a pressure of <1 mbar on a rotary evaporator, and a colorless mobile liquid is isolated, the .sup.29Si NMR spectrum of which indicates a D/T ratio of 7.62:1 (target: 8:1).

(3) The GPC has a broad molar mass distribution, characterized by M.sub.w=70317 g/mol; M.sub.n: 1941 g/mol and M.sub.w/M.sub.n=36.24.

(4) 2) Preparation of a Cyclic Branched Siloxane Having a Target D/T Ratio of 6:1 (Inventive)

(5) Analogously to Example 1, in a 500 ml four-neck round-bottom flask with a precision glass stirrer and a reflux condenser on top, 52.2 g (0.293 mol) of methyltriethoxysilane are heated to 60 C. together with 130.3 g (0.351 mol) of decamethylcyclopentasiloxane in 200 ml of toluene while stirring, 0.400 g of trifluoromethanesulfonic acid is added and the mixture is equilibrated for 4 hours. Then 15.8 g of water and 4.0 g of ethanol are added and the mixture is heated to reflux temperature at about 80 C. for a further 4 hours. The reflux condenser is exchanged for a distillation system, and the constituents that are volatile up to 100 C. are distilled off within the next hour. Then the distillation system is replaced by a reflux condenser, 7.90 g of water and 2.0 g of ethanol are added to the mixture and the mixture is left to boil for a further hour. The reflux condenser is then replaced once again by a distillation system, and the constituents that are volatile up to 100 C. are removed over the course of the next hour. The mixture is cooled to 60 C. and then 4 m % of sodium hydrogencarbonate is added, the mixture is stirred for half an hour, then the salt is separated from the liquid phase with the aid of a fluted filter. The volatiles are distilled off at 70 C. and a pressure of <1 mbar on a rotary evaporator, and a colorless mobile liquid is isolated, the .sup.29Si NMR spectrum of which indicates a D/T ratio of 5.85:1 (target: 6:1).

(6) 3) Preparation of a Greater Amount of a Cyclic Branched Siloxane Having a Target D/T Ratio of 6:1 (Inventive)

(7) In a 4000 ml four-neck round-bottom flask with a precision glass stirrer and a reflux condenser on top, 261.0 g (1.46 mol) of methyltriethoxysilane are heated to 60 C. together with 652.5 g (1.76 mol) of decamethylcyclopentasiloxane and 200 ml of toluene while stirring, 1.983 g of trifluoromethanesulfonic acid is added and the mixture is equilibrated for 4 hours. Then 79.0 g of water and 19.75 g of ethanol are added and the mixture is heated to reflux temperature at about 80 C. for a further 4 hours. The reflux condenser is exchanged for a distillation system, and the constituents that are volatile up to 100 C. are distilled off within the next hour. Then the distillation system is replaced by a reflux condenser, 26.30 g of water and 6.6 g of ethanol are added to the mixture and the mixture is left to boil for a further hour. The reflux condenser is then replaced once again by a distillation system, and the constituents that are volatile up to 100 C. are removed over the course of the next hour. The mixture is cooled to 60 C. and then 4 m % of sodium hydrogencarbonate is added, the mixture is stirred for half an hour, then the salt is separated from the liquid phase with the aid of a fluted filter. The volatiles are distilled off at 70 C. and a pressure of <1 mbar on a rotary evaporator, and a colorless mobile liquid is isolated, the corresponding .sup.29Si NMR spectrum of which indicates a D/T ratio of 5.74:1 (target: 6:1). The dynamic viscosity is 598 mPas at 25 C. The GC shows residual contents of D.sub.4=3.2%, D.sub.5=3.9% and D.sub.6=1.4%.

(8) The GPC has a broad molar mass distribution, characterized by M.sub.w=91965 g/mol; Mn: 2214 g/mol and M.sub.w/M.sub.n=41.54.

(9) 4) Preparation of a Cyclic Branched Siloxane Having a Target D/T Ratio of 4:1 (Unadjusted Amount of Solvent)

(10) Analogously to Example 1, in a 500 ml four-neck round-bottom flask with a precision glass stirrer and a reflux condenser on top, 73.5 g (0.412 mol) of methyltriethoxysilane are heated to 60 C. together with 122.3 g (0.33 mol) of decamethylcyclopentasiloxane in 220 ml of toluene while stirring, 0.436 g of trifluoromethanesulfonic acid is added and the mixture is equilibrated for 4 hours. Then 22.3 g of water and 5.6 g of ethanol are added and the mixture is heated to reflux temperature at about 80 C. for a further 4 hours. The reflux condenser is exchanged for a distillation system, and the constituents that are volatile up to 100 C. are distilled off within the next hour. Then the distillation system is replaced by a reflux condenser, 7.50 g of water and 1.9 g of ethanol are added to the mixture and the mixture is left to boil for a further hour. The reflux condenser is then replaced once again by a distillation system. In the course of the subsequent distillation, the viscosity of the bottoms rises so significantly that the mass of silicone gelates and is discarded.

(11) 5) Preparation of a Cyclic Branched Siloxane Having a Target D/T Ratio of 4:1 (Inventive, Adjusted Amount of Solvent of 1:3)

(12) Analogously to Example 1, in a 500 ml four-neck round-bottom flask with a precision glass stirrer and a reflux condenser on top, 36.8 g (0.206 mol) of methyltriethoxysilane are heated to 60 C. together with 61.2 g (0.165 mol) of decamethylcyclopentasiloxane in 330 ml of toluene while stirring, 0.218 g of trifluoromethanesulfonic acid is added and the mixture is equilibrated for 4 hours. Then 11.2 g of water and 2.8 g of ethanol are added and the mixture is heated to reflux temperature at about 80 C. for a further 4 hours. The reflux condenser is exchanged for a distillation system, and the constituents that are volatile up to 100 C. are distilled off within the next hour. Then the distillation system is replaced by a reflux condenser, 2.70 g of water and 0.9 g of ethanol are added to the mixture and the mixture is left to boil for a further hour. The reflux condenser is then replaced once again by a distillation system, and the constituents that are volatile up to 100 C. are removed over the course of the next hour. The mixture is cooled to 60 C. and then 4 m % of sodium hydrogencarbonate is added, the mixture is stirred for half an hour, then the salt is separated from the liquid phase with the aid of a fluted filter. The volatiles are distilled off at 70 C. and a pressure of <1 mbar on a rotary evaporator, and a colorless mobile liquid is isolated, the .sup.29Si NMR spectrum of which indicates a D/T ratio of 3.6:1 (target: 4:1).

(13) The GPC has a molar mass distribution characterized by M.sub.w=12344 g/mol; M.sub.n:3245 g/mol and M.sub.w/M.sub.n=2.63.

(14) 6) Preparation of a Branched Hydrosiloxane Having Terminal SiH Functions from the Cyclic Branched Siloxane Prepared in Example 1 with ,-dihydropolydimethylsiloxane and decamethylcyclopentasiloxane

(15) 37.4 g of the cyclic branched siloxane prepared in Example 1 are heated to 40 C. together with 6.3 g of an ,-dihydropolydimethylsiloxane (SiH value: 2.90 eq/kg) and 186.3 g of decamethylcyclopentasiloxane with addition of 0.25 g of trifluoromethanesulfonic acid (0.1 m % based on the overall mixture) in a 500 ml four-neck flask with precision glass stirrer and a reflux condenser on top for 6 hours, then 5 g of sodium hydrogencarbonate were added and the mixture was stirred for a further 30 minutes. With the aid of a filter press (Seitz K 300 filter disc), the salt was separated from the equilibrate.

(16) What is obtained is a colorless branched hydrosiloxane having dimethylhydrosiloxy functions in its termini (SiH value: 0.30 eq/kg). The corresponding .sup.29Si NMR spectrum confirms the target structure.

(17) 7) Preparation of a Branched Siloxane Having Terminal Ethoxy Functions (Inventive)

(18) 114.8 g of the cyclic branched siloxane prepared in Example 2 are heated to 60 C. together with 33.9 g of dimethyldiethoxysilane and 101.1 g of decamethylcyclopentasiloxane with addition of 0.25 g of trifluoromethanesulfonic acid (0.1 m % based on the overall mixture) in a 500 ml four-neck flask with precision glass stirrer and a reflux condenser on top for 6 hours, then 5 g of sodium hydrogencarbonate were added and the mixture was stirred for a further 30 minutes. With the aid of a filter press (Seitz K 300 filter disc), the salt was separated from the equilibrate.

(19) The corresponding .sup.29Si NMR spectrum confirms the target structure.

(20) 8) Preparation of a Branched Siloxane Having Terminal Vinyl Functions (Inventive)

(21) 109.2 g of the cyclic branched siloxane prepared in Example 3 are heated to 60 C. together with 41.3 g of divinyltetramethyldisiloxane and 99.5 g of decamethylcyclopentasiloxane with addition of 0.25 g of trifluoromethanesulfonic acid (0.1 m % based on the overall mixture) in a 500 ml four-neck flask with precision glass stirrer and a reflux condenser on top for 6 hours, then 5 g of sodium hydrogencarbonate were added and the mixture was stirred for a further 30 minutes. With the aid of a filter press (Seitz K 300 filter disc), the salt was separated from the equilibrate.

(22) The corresponding 29Si NMR spectrum confirms, as the target structure, a branched siloxane bearing terminal vinyl functions.

(23) 9) Preparation of a Branched Silicone Oil (Inventive)

(24) 111.6 g of the cyclic branched siloxane prepared in Example 3 are heated to 60 C. together with 36.7 g of hexamethyldisiloxane and 101.7 g of decamethylcyclopentasiloxane with addition of 0.25 g of trifluoromethanesulfonic acid (0.1 m % based on the overall mixture) in a 500 ml four-neck flask with precision glass stirrer and a reflux condenser on top for 6 hours, then 5 g of sodium hydrogencarbonate were added and the mixture was stirred for a further 30 minutes. With the aid of a filter press (Seitz K 300 filter disc), the salt was separated from the equilibrate.

(25) The corresponding 29Si NMR spectrum confirms, as the target structure, a branched non-functional silicone oil.

(26) 10) Preparation of a Branched Sulfato-Bridged Siloxane Having Terminal Chlorine Functions (Chlorosiloxanyl Sulfate, Inventive)

(27) a) Preparation of a Linear Chlorosiloxanyl Sulfate Precursor

(28) A 500 ml four-neck flask with precision glass stirrer and internal thermometer and with a reflux condenser on top is initially charged with 105.4 g of an ,-dichloropolydimethylsiloxane of mean chain length N=5.5 together with 28.2 g of decamethylcyclopentasiloxane while stirring, and 5.6 g of concentrated sulfuric acid are added. The mixture is left to reactor at 50 C. for one hour and then at 100 C. for 2 hours. After cooling to 20 C., a colorless clear liquid is obtained.

(29) b) Equilibration of the Precursor Having D/T Cycles Obtained in a)

(30) 110.8 g of a D/T siloxane prepared in analogy to Example 2 with a D/T ratio determined by .sup.29Si NMR spectroscopy of 5.63:1 are added to the precursor obtained in a) while stirring within 5 minutes.

(31) The equilibration is effected with vigorous stirring of the reactants at 22 C. for 30 minutes, then at 50 C. for 1 hour and at 100 C. for 6 hours.

(32) With application of an auxiliary vacuum of 1 mbar, volatile constituents are removed at 50 C. over a period of 2 hours. After the liquid phase has been cooled, a water-clear colorless liquid having an acid value of 1.82 mmol of acid/g of substance (theoretically: 1.853 mmol of acid/g of substance) is isolated. .sup.29Si NMR spectroscopy confirms the desired structure.