DE4323185C1 - Process for the preparation of polyorganosiloxanes - Google Patents

Abstract

The invention relates to a process for the preparation of polyorganosiloxanes by reacting polyorganosiloxanes containing silanol groups with one another or with polyorganosiloxanes containing triorganosiloxy terminal groups, in the presence of a silicon-, phosphorus-. nitrogen- and chlorine-containing catalyst which is a product of the reaction of phosphorus nitrile chloride with tris(triorganosiloxypolyorganosiloxanyl) phosphate.

Description

The invention relates to a process for the production of poly organosiloxanes by reacting polyorganosiloxanes that Have silanol groups, with each other or with polyorganosilo xanes which have triorganosiloxy end groups in the presence a containing silicon, phosphorus, nitrogen and chlorine Catalyst, which is a reaction product of phosphorite ril chloride with tris (triorganosiloxypolyorganosiloxanyl) represents phosphate. Polyorganosiloxanes are starting materials for various silicone rubber products.

Compositions containing phosphorus nitrile chlorides for the Polycondensation / polymerization of oligomeric polyorganosilo xanes are known (DE-AS 12 79 019, US Pat. No. 3,839,388). When Solvents are e.g. B. benzene, toluene, petroleum ether, halo Genetic hydrocarbons, ethers and ketones proposed (U.S. Patent 3 652 711). Excellent solvent for catalytically active Phosphorus nitrile chlorides are halogenated hydrocarbons, such as. B. Methylene chloride (US Pat. No. 3,839,388), so produced Lö solutions retain their catalytic activity for a long time Period. However, the use of methylene chloride should just like that of other chlorinated hydrocarbons toxicity can be avoided.

Because the phosphoronitrile chlorides only in low concentrations their solutions are particularly vulnerable against contamination in the solvents used or against hydrolysis, e.g. B. by the water content of the air. That's why solutions of this type often only have a low storage stability as well as a limited time activity.

Solvents such as ethers, ketones and esters that are not complete dig are inert to the phosphonitrile chlorides to deactivate the catalyst with darkening the entire solution.  

To avoid the disadvantages described, it was proposed gene, phosphonitrile chlorides with a mixture of cyclic dime implement thylsiloxanes (JP-A 01 004 528, DE 37 25 377). It is only possible, however, low-viscosity and therefore metered Pro to obtain products when the content of phosphorus nitrile chloride compared to the polyorganosiloxane is relatively high. also these compositions are not inert to moisture and react with an increase in viscosity.

As another way of making stable kata Analyzer solutions are described in EP 381 204 the use of surfactants or crown ethers as solubilizers, e.g. B. to acetic acid reethylester described as a solvent. This method is due to the multi-stage production of the catalyst solution solution complex. In addition, the surfactants or Crown ether, in contrast to the usual solutions during the polycondensation of the siloxane oligomers be removed and interfere with the processing of the bottom lymers.

The object of the present invention was to provide a catalyst find the one for polycondensation and / or equilibria tion of polyorganosiloxanes highly effective in any primarily low, concentrations can be produced and in the polyorganosiloxanes to be converted soluble and free of Lö is. Furthermore, the Kataly according to the invention sator homogeneous, it must have a high stability with respect Have activity and viscosity and must not be additional acidic components that increase the neutralization effort and / or possibly additional corrosion risks evoke, contain.

According to the invention, the catalyst is a reaction product of phosphonitrile chloride with a tris (triorganosiloxypoly organosiloxanyl) phosphate of the general formula

[R₃SiO (R₂SiO) _m ] ₃P = O (I),

where R independently of one another the same or different, un saturated and / or saturated, monovalent hydrocarbon residues  with 1 to 6 carbon atoms and m means either 0 or 3 is up to 100.

The catalyst of the invention is extremely suitable for Condensation and / or equilibration reactions in the Um setting of polyorganosiloxanes which have silanol groups, with each other or with polyorganosiloxanes, the triorganosiloxy have end groups. It is usually used in quantities of 1 up to 1000 ppm by weight, based on the weight of each used Deten amount of polyorganosiloxanes used. Preferred who the 1 to 50 ppm by weight of catalyst, based on the amount Phosphoronitrile chloride, which when reacted with Tris (triorga nosiloxypolyorganosiloxanyl) phosphate is used det.

As polyorganosiloxanes which have silanol groups, who preferably uses the α, ω-dihydroxypolyorganosiloxanes of the general formula HO (SiR₂O) _r H and as polyorganosiloxanes which have triorganosiloxy groups, preferably α, ω-trimethyl siloxypolyorganosiloxanes of the general formula R (R₂SiO) _s SIR₃ , wherein R independently of one another the same or different, saturated and / or unsaturated, monovalent hydrocarbon radicals having 1 to 6 carbon atoms and r and s have a value greater than 2.

The tris (triorganosiloxypolyorganosiloxanyl) phosphate of all base formula

[R₃SiO (R₂SiO) _m ] ₃P = O (I),

in the case of m = 0, can be obtained, for example, by Conversion of equivalent amounts of triorganohalosilane, such as B. trimethylchlorosilane or dimethylvinylchlorosilane, and orthophosphoric acid, the orthophosphoric acid containing tenes water with the equivalent amount of triorganohalosilane is bound.

The tris (triorganosiloxypolyorganosiloxanyl) phosphate of all base formula

[R₃SiO (R₂SiO) _m ] ₃P = O (I),

where m is 3 to 100 can be obtained, for example, by reacting a tris (triorganosiloxypolyorganosiloxanyl) phosphate of the general formula (I), in which m = 0, with one or more organocyclosiloxanes of the general formula (R₂SiO) _q (II) , wherein R independently of one another the same or different, saturated and / or unsaturated; means monovalent hydrocarbon radicals with 1 to 6 carbon atoms and q assumes values from 3 to 6, in molar ratio from 1: 1 to 50: 1.

However, it is also possible to use Tris (triorganosiloxypolyorgano siloxanyl) phosphates of the general formula (I), where m values assumes between 0 and 100, according to any other known ver drive to manufacture.

It is advantageous for the production of the catalyst a tris (triorganosiloxypolyorganosiloxanyl) phosphate with a Ratio of trialkylsiloxy to dialkylsiloxy units set, which that of a polyorganosiloxane with Trialkylsi Loxy end groups with a viscosity of, for example, 500 to 10,000 mPa · s, preferably of about 1000 mPa · s. This makes it possible to carry out any catalytic activities depending on the viscosity of the catalyst.

The cyclic siloxanes are e.g. B. made by alkali depolymerization of hydrolysis of diorganodi chlorosilanes resulting products. They exist for the most part part from octaorganocyclotetrasiloxane (D₄). Advantageous The mixture obtained is usually used. However, it is also possible to use special cyclosiloxanes.

The catalyst can be produced both at room temperature structure as well as at elevated temperature. At higher However, temperatures can occur due to siloxane cleavages.

The phosphoronitrile chloride used consists essentially of compounds or mixtures of these compounds of the general formula [Cl₃PN (PCl₂N) _x PCl₃] ⁺ _* [P _y Cl _{5y + 1} ] ⁻, where x is an integer greater than or equal to 0 and y = 0 or 1 means. It is obtained, for example, by reacting 2 moles of phosphorus tachloride with 1 mole of ammonium chloride. No. 3,839,388. Phosphorus nitrile chloride can be reacted with tris (triorganosiloxypolyorganosilo xanyl) phosphate of the general formula [R₃SiO (R₂SiO) _m ] ₃P = O (I) in any ratio. It can be used as a pure solid or as a solution, e.g. B. dissolved in methylene chloride, but if the solution is used, the solvent must be removed after the reaction.

After the condensation and / or equilibration in the presence of the catalyst according to the invention, the polyorganosiloxane obtained, which preferably has a viscosity in the range from 2 · 10 ^-1 to 10⁵ Pa · s, can be neutralized or stabilized. Compounds with epoxy groups, n-butyl lithium or amines can be used for this purpose.

For example, the polyorganosiloxane obtained according to Er an amine of the general formula is sufficient for the target viscosity

R ′ _n NH _3-n (III),

wherein R 'same or different, saturated hydrocarbons material residues with 1 to 10 carbon atoms and / or R₃Si group pen means where R is independently the same or ver different, saturated or unsaturated hydrocarbons 1 to 6 carbon atoms and n values between 1 and 3 assumes, preferably in amounts of 0.005 to 1 wt .-%, be drew on the weight of the amount of polyorganosi used loxane. Trialkylamine is preferred, such as B. triisooctylamine, or hexaorganodisilazane, such as. B. Hexamethyldisilazane or tetramethyl-divinyl-disilazane, for Commitment.

According to the procedure according to the invention, a solution medium-free, containing silicon, phosphorus, nitrogen and chlorine tender catalyst with any viscosity as well as catalytic activities that are clear and colorless, Activity and viscosity even over a long period of time not changed under the influence of moisture and at least the same activity as that dissolved in methylene chloride Has phosphonitrile chloride. He is deployed in the Polyorganosiloxanes soluble in all proportions.

Embodiments

All work for the preparation of the catalyst according to the invention tors were made under the strict exclusion of air humidity, e.g. B. performed in a dry nitrogen atmosphere.

example 1

5 ml of a 10 vol .-% phosphonitrile chloride solution in methyl Enchloride were mixed with 8 g of the reaction product from one part Tris (trimethylsilyl) phosphate and nine parts of a mixture from cyclic dimethylsiloxanes (80 wt .-% D₄) mixed. After standing at room temperature for about three hours 91.5 g cycle mixture added. After standing again The solution was colorless and complete for about two hours clear. The methylene chloride was added by vacuum distillation 10 mbar and max. 50 ° C away. The implementation product pointed a viscosity of approx. 1000 mPa · s at 25 ° C.

Example 2

20 ml of a 10 vol .-% phosphonitrile chloride solution in Me ethylene chloride were mixed with 8 g of the reaction product from a Part of tris (trimethylsilyl) phosphate and nine parts of Cyclenge mixed from Example 1. After standing for about three hours at room temperature, a further 90 g of the cyclic mixture of be known composition added. After another, about two Standing for hours became a colorless and completely clear solution receive. The methylene chloride was removed by vacuum distillation at 10 mbar and max. 50 ° C away. The product obtained had a viscosity of approx. 1000 mPa · s at 25 ° C.

Example 3

Analogous to Example 2, with the difference that 2 g of pure Phos phornitrile chloride were used. Methylene chloride needed not to be removed.  

Example 4-A

In a 350 ml sulfonation flask equipped with dissolver mixer rer, internal thermometer and still, 150 g egg nes α, ω-dihydroxypolydimethylsiloxanes with a viscosity of 160 mPa · s at 25 ° C heated to 100 ° C with stirring. After To administration of 300 ul of the catalyst prepared according to Example 1 the pressure in the reaction vessel was reduced to 100 mbar. After 5 min, measured from the time the catalyst was added, de vented the reaction vessel. Within a further 5 min the 4.5 ul triiosooctylamine mixed.

The α, ω-dihydroxypolydimethylsiloxane obtained had one Viscosity of 293 Pa · s at 25 ° C.

Example 4-B

The procedure was analogous to Example 4-A, with the difference that that as a catalyst 300 ul of a 0.5 vol .-% solution of Phosphonitrile chloride in methylene chloride, made by Reaction of 2 moles of phosphorus pentachloride with 1 mole of ammonium chloride was used.

The α, ω-dihydroxypolydimethylsiloxane obtained had only one Viscosity of 157 Pa · s at 25 ° C, which means the lower Ak activity of the conventional phosphonitrile chloride solution demon is treated.

Example 5

A laboratory thin film evaporator was used continuously 2 kg / h of an α, ω-dihydroxypolydimethylsiloxane of a viscose of 160 mPa · s at 25 ° C and with 2 ml / h of according to the example 1 catalyst prepared. The temperature at the Evaporator surface was 80 ° C, the pressure 100 mbar. The continuously after an average dwell time of 60 s Product carried was with 0.6 ml of a 10 vol% solution of triisooctylamine in an α, ω-dihydroxypolydimethylsiloxane a viscosity of 160 mPa · s mixed at 25 ° C.

The α, ω-dihydroxypolydimethylsiloxane produced had one Viscosity of 343 Pa · s at 25 ° C.  

Example 6

In a 350 ml sulfonation flask with dissolver stirrer, internal therm The meter and distillation attachment were 150 g of a mixture 96.5% by weight of α, ω-dihydroxypolydimethylsiloxane with a viscosity of 160 mPa · s at 25 ° C and 3.5 wt .-% α, ω-bis (trimethylsil oxy) polydimethylsiloxane with 4.76% by weight trimethylsiloxy-a units heated to 100 ° C with stirring. After adding 0.6 ml of the catalyst prepared according to Example 1 was the Pressure in the reaction vessel reduced to 20 mbar. After 30 min, measured from the time of catalyst addition, the reak vented. Then 5.4 ul of hexamethyldisilazane mixed in.

The α, ω-bis (trimethylsiloxy) polydimethylsiloxane obtained showed a viscosity of 16 700 mPa · s at 25 ° C and an IR Spectroscopically determined content of silicon-bound Hy droxyl groups of <30 ppm.

Example 7

Mixing was carried out in a heated two-shaft vacuum kneader and heated to 100 ° C: 8.0 kg of α, ω-dihydroxypolydimethylsilo x at a viscosity of 160 mPas at 25 C, 0.02 kg α, ω-bis (Dimethylvinylsiloxy) dimethylsiloxane with 10% by weight dimethyl vinylsiloxy units and 0.12 kg α,% ω-dihydroxypolymethylvi nylsiloxane with a viscosity of 9500 mPa · s at 25 ° C, the 4.7 % By weight contained silicon-bonded vinyl groups. After encore of 8 g of the catalyst prepared according to Example 2 the pressure in the kneader was reduced to 9 mbar. After a reak tion time of two hours was aerated with nitrogen and then 8 g of tetramethyldivinyldisilazane are mixed in. To The pressure in the reaction space was increased to 4 for a further two hours mbar and the mixture can be stirred at 120 ° C. for one hour tet.

The α, ω-bis (diinethylvinylsiloxy) polydimethylsil obtained oxy-methylvinylsiloxane had a viscosity of 56,000 Pa · s 25 ° C. As evidence of the greatest possible freedom from silicon-bonded hydroxyl groups were 3 g of a mixture from 20% by weight of dibutyltin laurate and 80% by weight of tetraethoxysilane in 60 g of the polysiloxa obtained in the manner described  nes in a plastograph at a test temperature of 20 ± 1 ° C worked in for an hour. There was no viscosity increase in activity observed.

Example 8

A laboratory thin film evaporator was continuously operated at 1.4 kg / h α, ω-dihydroxypolydimethylsiloxane with a viscosity of 160 mPa · s at 25 ° C, 0.07 kg / h α, β-bis (trimethylsiloxy) polydime thylsiloxane with 4.76 wt .-% trimethylsiloxy units and with 2.8 ml / h of the catalyst prepared according to Example 1 loaded. The temperature on the evaporator surface was 100 ° C, the pressure 8 mbar. That after a medium stay time of 75 s continuously discharged product was with 60 ml / h of a 0.05 vol% solution of hexamethyldisilazane in an α, ω-bis (trimethylsiloxy) polydimethylsiloxane of a Vis viscosity of 1000 mPa · s mixed at 25 ° C.

The α, ω-bis (trimethylsiloxy) polydimethylsiloxane obtained had a viscosity of 33 Pa · s at 25 ° C.

Claims (8)

1. A process for the preparation of polyorganosiloxanes by reacting polyorganosiloxanes which have silanol groups with one another or with polyorganosiloxanes which have triorganosiloxy end groups in the presence of a catalyst, characterized in that the catalyst is a reaction product of phosphonitrile chloride with a tris (triorganosiloxypolyorganosiloxa nyl) phosphate of the general formula [R₃SiO (R₂SiO) _m ] ₃P = O (I), in which R is independently the same or different, unsaturated and / or saturated monovalent hydrocarbon radicals having 1 to 6 carbon atoms and m is either 0 or 3 to 100 , represents. 2. The method according to claim 1, characterized in that the Catalyst in amounts of 1 to 1000 ppm by weight, based on the Weight of the amount of polyorganosiloxanes used, is used. 3. The method according to claim 1, characterized in that the Ratio of trialkylsiloxy to dialkylsiloxy units in Tris (triorganosiloxypolyorganosiloxanyl) phosphate that one Polyorganosiloxane with trialkylsiloxy end groups of a viscose corresponds to 500 to 10,000 mPa · s. 4. The method according to claim 3, characterized in that the Ratio of trialkylsiloxy to dialkylsiloxy units in Tris (triorganosiloxypolyorganosiloxanyl) phosphate that one Polyorganosiloxane with trialkylsiloxy end groups of a viscose 1000 mPa · s corresponds.   5. The method according to claim 1, characterized in that the tris (triorganosiloxypolyorganosiloxanyl) phosphate of the general formula [R₃SiO (R₂SiO) _m ] ₃P = O (I), in which m = 0, is obtained by reacting equivalent amounts of Triorganohalosilane and orthophosphoric acid, and water contained in the orthophosphoric acid is bound with the equivalent amount of triorganohalosilane. 6. The method according to claim 1 and 5, characterized in that the tris (triorganosiloxypolyorganosiloxanyl) phosphate of the general formula [R₃SiO (R₂SiO) _m ] ₃P = O (I), wherein m is 3 to 100, is obtained by reacting a tris (triorganosiloxypolyorganosiloxanyl) phosphate of the general formula (I), where m = 0, with one or more organocyclosiloxanes of the general formula (R₂SiO) _q (II), in which R has the meaning given in claim 1 and q has values from 3 to 12 assumes in a molar ratio of 1: 1 to 50: 1. 7. The method according to claim 5, characterized in that as Triorganohalosilane trimethylchlorosilane is used. 8. The method according to claim 5, characterized in that as Triorganohalosilane Dimethylvinylchlorsilan is used.