DE102014226725A1 - Process for the equilibration of low molecular weight compounds - Google Patents

Abstract

A process for the preparation of organopolysiloxanes by equilibration reaction in which low molecular weight organosiloxanes are contacted with ion exchange resin particles which are fluidized with inert gas and allowed to react.

Description

The invention relates to a method for the equilibration of low molecular weight compounds formed in the co-hydrolysis of chlorosilanes.

The preparation of equilibration products, especially of acidic ion exchange resins, has been known for a very long time. Already in DE-A 2152270 describes how equilibration products of organosiloxanes can be prepared. Furthermore, in DE 10311724 A1 as part of the Siloxanerzeugung described the equilibration by means of strongly acidic ion exchange resins. US-A 6,534,614 describes the increase of the linear portion of a co-hydrolyzate by reaction on a sulfonic acid cation exchanger in a fixed bed. For the preparation of branched SiH-functional siloxanes is in DE-A 102008041601 the use of a mixture consisting of trifluoromethanesulfonic acid and sulfonic acid ion exchanger disclosed. In DE 102005001039 A1 the cation exchanger is characterized in terms of specific surface area, average pore diameter and the product of both (P = specific surface area x mean pore diameter), ie these parameters have a decisive influence on the required product quality. Also, the water content of the catalyst used is often considered. WO 2010/074831 A1 quantifies the water content of the ion exchange resin at 6-19%, in DE 102008042181 A1 this is even higher with 8-25%. In addition, in WO 2010/074831 A1 described the repeated application of water to reactivate the catalyst again.

The regeneration of the ion exchange resins with the goal of reuse is important for environmental and economic reasons. Especially by water, which is formed by condensation of OH groups, and gel particles or highly viscous compounds, the ion exchange resin can become inactive. Only the removal of water by drying is often insufficient. In EP-A 1367079 is used for the laundry, a low molecular weight siloxane. Due to the boiling point and solubility, hexamethyldisiloxane is particularly suitable. This can be easily evaporated under a slight vacuum and temperatures below 100 ° C. The injection of air or nitrogen would also be possible. The water content of the ion exchanger can thus be reduced to 5-7%. For regeneration, however, it is necessary to switch to another equilibration reactor or the process is interrupted for the duration of the cleaning or regeneration. There are cleaning products that need to be disposed of.

Most effective equilibration is carried out continuously in a tubular reactor. Such a reactor packed with a heterogeneous acidic catalyst is disclosed in US Pat US2004 / 0176561 A1 comprehensively described. Again, it is written about the deactivation, for example, by deposits on the active centers of the catalyst and water absorbed on the catalyst particles.

The invention relates to a process for the preparation of organopolysiloxanes by equilibration reaction in which low molecular weight organosiloxanes with ion exchange resin particles, which are fluidized with inert gas, are brought into contact and allowed to react.

Equilibrating reactions are understood to mean the equilibration of siloxane bonds, in particular the formation of linear siloxane structures from cyclic siloxanes.

The low molecular weight siloxanes to be equilibrated may be any desired and known linear, cyclic or branched siloxanes having preferably 2 to 100 silicon atoms.

The low molecular weight siloxanes used according to the invention are preferably mixtures of siloxanes with a proportion of cyclic siloxanes of preferably more than 60% by weight, particularly preferably 70 to 85% by weight.

The low molecular weight siloxanes may be used in the process according to the invention as such or in admixture with other substances, e.g. Silanes and / or such organic solvents that are not involved in the reaction can be used. The silanes which can be used in admixture with the low molecular weight siloxanes are preferably methylchlorosilanes, phenylchlorosilanes and alkoxysilanes.

The siloxanes to be equilibrated according to the invention, optionally mixed with other substances, are referred to as the feed mixture. This is liquid at 20 ° C and 1013 hPa.

The siloxanes used according to the invention are preferably those obtainable by hydrolysis or condensation of chlorosilanes of the formula R _a SiH _b Cl _4-ab (I), in which
R may be the same or different and represents a monovalent, optionally substituted hydrocarbon radical,
a is 1, 2 or 3 and
b is 0 or 1,
with the proviso that the sum a + b is less than or equal to 3.

Radicals R are preferably hydrocarbon radicals having 1 to 12 carbon atoms, more preferably the methyl, ethyl, phenyl or vinyl radical.

The silanes of the formula (I) are preferably Me ₂ SiCl ₂ , Me ₃ SiCl, Me ₂ SiHCl, MeSiHCl ₂ Me ₂ ViSiCl, MePhSiCl ₂ or Ph ₂ SiCl ₂ and mixtures thereof with Me equal to methyl radical, Vi equal to vinyl radical and Ph is phenyl.

The hydrolysis or condensation of silanes of the formula (I) can be carried out by suitable methods. The hydrolysis or condensation of silanes of the formula (I) is preferably carried out by reacting the chlorosilanes with water, if appropriate in the presence of a water-insoluble solvent and subsequent distillation of the hydrolysates obtained, e.g. at a pressure of 1 to 50 hPa, and partial or complete removal of the water from the distillate. Preferably, the water content of the distillate is reduced to a minimum, which can be done for example with the aid of a so-called coalescer, a droplet separator. For this, the distillate is first passed through a droplet separator. At its fibers, many water droplets, which then run from a certain size of the fibers of the coalescer down into a separation vessel.

The proportion of cyclic siloxanes in the hydrolyzate varies depending on the silanes used and the hydrolysis conditions.

The term hydrolyzate is intended in the context of the present invention to include complete hydrolysis, partial hydrolysis and cohydrolysis of silanes and condensation reactions of resulting hydroxysilanes with elimination of water.

The mixture to be equilibrated is preferably optically clear. In the mixture to be equilibrated, the total content of OH groups, Si-bonded OH groups and also of water is preferably at most 4000 to 5000 ppm by weight, more preferably at most 2000 ppm by weight. Clearly contained traces of water (water pearls) or heavily clouded products mean that either significantly more inert gas is required for the operation of the equilibration reactor or the ion exchanger becomes inactive.

The feed mixture used according to the invention is particularly preferably the part of the hydrolyzate of Me ₂ SiCl ₂ and Me ₂ ViSiCl which is removed by distillation at 1 to 50 hPa and at temperatures of 130 to 190 ° C., based on Si
0-1.4 mol% tetramethyldivinyldisiloxane (M ^Vi M ^Vi ),
5.1-6.1 mol% dimethylvinylsiloxane units (M ^Vi ),
0.7-1.4 mol% dimethylhydroxysiloxane units (M ^OH ),
0.4-1.3 mol% hexamethylcyclotrisiloxane D ₃ ,
54-60 mol% octamethylcyclotetrasiloxane D ₄ and
33-38 mol% of polydimethylsiloxane units D _n (linear), the sum of the individual constituents being 100 mol%.

The feed mixture may contain traces of water and / or aqueous HCl, which is not preferred.

The viscosity of the feed mixture is preferably 2 to 10 mm ² / s, more preferably 2 to 5 mm ² / s.

The feed mixtures, as in the case of co-hydrolysis of methyldichlorosilane and trimethylchlorosilane, may also include SiH-containing cyclics, e.g. Cyclotetrasiloxane, cyclopentasiloxane and higher cyclosiloxanes, as well as hexamethyldisiloxane and solvents such as toluene.

The ion exchange resin used as a catalyst in the process according to the invention may be any of the ion exchange resins which have hitherto been used in equilibration reactions, e.g. strong, easily product-separable, near-abrasion-free, acidic or basic macroporous ion exchangers, such as those based on styrene-divinylbenzene copolymers functionalized with sulfonic acid groups.

The ion exchange resin used as a catalyst in the process according to the invention is solid under the reaction conditions and is in the form of particles, in particular in spherical form. Excellent and preferred is a macroporous strongly acidic cation exchanger having a specific surface area of preferably 35 to 50 m ² / g, an average pore diameter of preferably 25 to 43 nm and a total weight capacity (H ⁺ form) of preferably at least 5.2 eq / kg, (Germany) GmbH, such as ion exchange resin available under the trade names Purolite ^® CT269DR the company. Purolite.

The determination of the water content in the ion exchange resin used can be carried out by various and known methods. Suitable for unloaded catalyst, ie catalyst which has not yet had contact with product to be equilibrated, is a furnace method. In this case, 10 g of ion exchange resin at 105 ° C and the pressure of the surrounding atmosphere, ie 900 to 1100 hPa, heated for a period of 3 hours in an oven, then reweighed. The difference corresponds to the water content. Already for equilibration catalysts used are reacted with trimethylchlorosilane in the presence of nitrogen having a purity of 99.99% by volume and the amount of hexamethyldisiloxane formed, from which it is possible to deduce the amount of water present, ie according to the formula 2 (CH ₃ ) ₃ SiCl + 1H ₂ O ==> (CH ₃ ) ₃ Si-O-Si (CH ₃ ) ₃ + 2HCl forms hexamethyldisiloxane, which is detected analytically by GC. The necessary amount of water was supplied by the catalyst and can be calculated.

In the method according to the invention, in particular when using a tube reactor filled with catalyst, the volume ratio of mixture to be equilibrated to catalyst is preferably almost 1: 1, the residence time on the catalyst being determined by the metering rate. As a result, volume ratios of catalyst to feed mixture of preferably 1: 1 to 1: 5 are set. The volume of the catalyst used according to the invention is to be understood as meaning the pure volume of the loose bed without pore volume.

The inert gas used according to the invention is preferably nitrogen, argon or helium, more preferably nitrogen, in particular nitrogen with a purity of 99.99% by volume.

The process according to the invention can be carried out continuously and batchwise, a continuous procedure being preferred. If a siloxane mixture is used as the feed mixture, which is separated by distillation from the hydrolyzate of chlorosilanes, and this is produced continuously, this can be carried out in a plant composite, which is preferred.

Any and previously known reaction vessels can be used in the process according to the invention. The reaction vessel is preferably a tubular reactor, the equilibration catalyst preferably being filled into the tube as a loose bed.

In the method according to the invention, inert gas is injected into the reaction vessel at such a rate that the ion exchange resin particles at least partially move. Often it is sufficient to keep the catalyst bed only slightly in motion. Since where traces of water have a decisive influence on the equilibration result or on the activity of the catalyst, preference is given to blowing in so much inert gas that the catalyst mixture is vigorously agitated over the entire reactor volume.

In the method according to the invention, the feed mixture can be arbitrarily, e.g. horizontally or vertically, are passed through the Ionenaustauscherbett.

In the method according to the invention, an upright tubular reactor is preferred for the equilibration, which is equipped with the equilibration catalyst in bulk. The feed mixture to be equilibrated and the inert gas used to agitate the catalyst are preferably passed through the tubular reactor from bottom to top, the feed mixture being introduced with a pump. For the nitrogen feed, a certain pressure is required to counteract the hydrostatic pressure of the mixture in the equilibration column. For the reactor dimension, the larger the quotient of length to diameter of the tube reactor, the more effective the equilibration, since the mixture to be equilibrated is more frequently in contact with the active centers of the catalyst. The length of the reactor is particularly preferably greater by a factor of 20 to 30 than its diameter.

In the process according to the invention, the volume of the reactor is preferably greater by a factor of 1.5 to 4 than the volume of the catalyst which the catalyst occupies in the reactor.

The equilibration according to the invention is carried out at temperatures of preferably 10 to 100 ° C., more preferably from 20 to 80 ° C., and preferably at a pressure of the surrounding atmosphere, that is about 900 to 1100 hPa. For SiH-containing products, temperatures of less than or equal to 40 ° C. are preferred because of the loss of hydrogen occurring.

Residence times of 10 to 60 minutes are preferred in the process according to the invention. With higher temperatures, e.g. 30 to 60 ° C, the residence time can be reduced, so that depending on the conditions 20 to 30 minutes residence time are common.

In the process according to the invention, the amount of catalyst, residence time and temperature are decisive for the degree of equilibration.

In order to ensure a low water content, ie a water content of preferably <3 wt .-%, after filling of the reactor, preferably the reactor temperature and the amount of inert gas are briefly increased significantly before starting the Equilbrierreaktors (starting process). Preference is given to temperatures in the range of 40 to 80 ° C for a period of preferably 30 to 60 minutes at an amount of nitrogen, which preferably corresponds to 1.5 to 3 times the amount of nitrogen used in the equilibration. Preferably, the Startup process performed in the absence of the feed mixture.

In the process according to the invention, after the equilibration has ended, the equilibrated product mixture is either supplied to the distillation or, if the feed mixture is obtained continuously from a hydrolyzate, fed to the hydrolyzate directly after the hydrolysis in order to introduce it homogeneously into the hydrolyzate, with the cycles remaining after the equilibration Low molecular weight siloxanes are separated in the subsequent to the hydrolysis distillation together with the low molecular weight organosiloxanes of the hydrolyzate.

In a preferred embodiment of the process according to the invention, low molecular weight organosiloxanes are optionally brought into contact and mixed with other substances with ion exchange resin particles which are fluidized with inert gas, and the equilibrated products are subsequently fed to the distillation. Preferably, in the case of the preferred tubular reactor at its head, the equilibrated product mixture is obtained by continuous overflow and is supplied continuously or discontinuously, preferably continuously, to the distillation by distillation.

A further preferred embodiment of the process according to the invention is characterized in that silanes of the formula (I) are reacted with water, if appropriate in the presence of a water-insoluble solvent, then distilled and the water is removed from the distillate partially or completely and the resulting siloxane mixture with ion exchange resin particles, which are fluidized with inert gas, are brought into contact and allowed to react and the equilibrated product mixture is subsequently supplied to the distillation by distillation.

After completion of the equilibration, the equilibrated product mixture, if the feed mixture is continuously recovered from a hydrolyzate, preferably recycled after the hydrolysis step in the process, where it is subsequently volatilized with the hydrolyzate and the volatiles are recirculated to equilibration.

A further preferred embodiment of the process according to the invention is characterized in that silanes of the formula (I) are reacted with water, if appropriate in the presence of a water-insoluble solvent, are subsequently distilled and the water is removed from the distillate partially or completely and the resulting siloxane mixture with ion exchange resin particles, which are fluidized with inert gas, is brought into contact and allowed to react and the equilibrated product mixture is added to the hydrolyzate directly after the hydrolysis to introduce it homogeneously into the hydrolyzate, wherein after equilibration remaining cycles or low molecular weight siloxanes in the the hydrolysis subsequent distillation are separated together with the low molecular weight organosiloxanes of the hydrolyzate.

The process according to the invention is outstandingly suitable for the preparation of low-volatility, usually chain-shaped siloxanes, the so-called silicone oils, preferably in the low to medium viscosity range.

By introducing inert gas, in particular nitrogen, and the concomitant turbulence of the ion exchange resin in the reaction vessel, in particular tubular reactor, the deactivation of the ion exchange resin is surprisingly avoided or the service life of the equilibration is significantly increased.

Advantageously, the water content does not increase any further and is even further reduced by the starting process of the equilibration catalyst.

The process according to the invention has the advantage that the ion exchange resin used does not have to be regenerated in a complex process in a batch process. Deactivation during the actual equilibration process is delayed or prevented by the reaction procedure according to the invention. The amounts of ion exchange resin to be disposed of in the absence of regeneration possibilities can advantageously be further reduced, especially since the ion exchanger is often so strongly solidified that regeneration is virtually impossible.

In the following examples, the viscosity was determined in addition to ²⁹ Si NMR analyzes to assess the equilibrium quality.

The viscosity is determined by means of falling ball viscometer according to DIN 53015 at 25 ° C.

In the following examples, the feed mixture flows through the vertical equilibration from bottom to top.

The following abbreviations are used:
Me - methyl radical and
Vi - vinyl rest.

Feed mixture E1:

From the hydrolyzate of Me ₂ SiCl ₂ and Me ₂ ViSiCl is obtained by hydrolysis and condensation and subsequent distillation at 5-15 hPa and 180 ° C continuously feed mixture E1, which has based on Si the following composition in mol%:
0-1.4 mol% tetramethyldivinyldisiloxane (M ^Vi M ^Vi ),
5.1-6.1 mol% dimethylvinylsiloxane units (M ^Vi )
0.7-1.4 mol% dimethylhydroxysiloxane units (M ^OH ),
0.4-1.3 mol% hexamethylcyclotrisiloxane D ₃ ,
54-60 mol% octamethylcyclotetrasiloxane D ₄ and
33-38 mol% polydimethylsiloxane units D _n (linear),
the sum of the components being 100 mol%.

Of M ^OH a result, the feed mixture contains E1 1500 to 2000 ppm by weight of silicon-bonded hydroxy groups, which form by condensation of the appropriate amount of water.

The feed mixture E1 has an initial viscosity of 2.7-23.9 mm / s.

example 1

Equilibrierreaktor:

Ø = 2.8 cm, h = 60 cm, double-jacket pipe, heatable.

In these Equilibrierreaktor 60 g of an ion exchange resin based on polystyrene functionalised with sulfonic acid groups in the form of spheres (commercially available (under the name Purolite ^® CT269DR at Purolite Germany) GmbH) loosely filled.

The feed mixture E1, which is obtained from a continuous hydrolysis process, and nitrogen are fed into the tube reactor below. In the feed mixture E1, this takes place in an amount of 150 to 155 ml / h with the aid of a membrane metering pump. Nitrogen is blown in at a rate of 20 l / h. The reaction temperature is 40 ° C.

At the top of the tubular reactor, the equilibrated product mixture is obtained by continuous overflow with retention of the catalyst by means of filter cloth and is continuously fed to the resulting from the continuous hydrolysis process hydrolyzate and volatilized the mixture by distillation. The first distillation step is carried out at 90 ° C and 100 hPa. Primarily, this first stage serves to separate water. In the second stage at about 180 ° C and 5 to 10 hPa, the volatile compounds are separated, which are contained in about 30 wt .-% in the mixture of hydrolyzate and product mixture. These are fed back to the continuous equilibration. In the bottom, predominantly linear siloxanes can be isolated as the target product.

To assess the equilibration quality, the viscosity of the equilibrated product mixture is measured. This increases from originally 2.7-3.9 mm ² / s to 20-22 mm ² / s, ie from the predominantly cyclic compounds have formed more than 85% linear siloxanes, which is confirmed by NMR studies. If the viscosity remains almost constant at the same level, this means that the equilibration catalyst still has its full activity.

The equilibration catalyst is still active after 65 kg or 70 l feed mixture.

Comparative Example 1

The procedure described in Example 1 is repeated, except that no nitrogen is used.

The equilibration catalyst is inactive and strongly solidified after 20 kg or 21.5 l of feed mixture. The viscosity of the equilibrated product mixture dropped from about 21.6 mm ² / s to 17.2 mm ² / s and the experiment was terminated.

Comparative Example 2

Equilibrierreaktor:

Ø = 1.8 cm, h = 53 cm, double-jacket pipe, heatable.

In these Equilibrierreaktor 40 g of an ion exchange resin based on polystyrene functionalised with sulfonic acid groups in the form of spheres (commercially available (under the name Purolite ^® CT269DR at Purolite Germany) GmbH) loosely filled.

The feed mixture E1 is fed into the tube reactor below in an amount of 100 to 105 ml / h by means of a diaphragm metering pump. The reaction temperature is 40 ° C in the reactor.

At the top of the tube reactor, the equilibrated product mixture is obtained by continuous overflow with retention of the catalyst by means of filter cloth and proceed as described in Example 1 on.

At the beginning of the equilibration, a viscosity of 22.1 mm ² / s is achieved.

The equilibration catalyst is inactive and strongly solidified after 15 kg or 16.1 l of feed mixture

Comparative Example 3

The procedure described in Comparative Example 2 is repeated with the modification that is used as feed mixture E2, which differs from E1 in that it additionally contains 0.5 wt .-% water or aqueous hydrochloric acid. Before being fed into the equilibration reactor, E2 is passed through a coalescer to remove traces of water, with water or aqueous hydrochloric acid being separated off in an amount of 0.55% by weight.

The equilibration catalyst is inactive and strongly solidified after 22 kg or 23.7 l of feed mixture.

• R1 erste Regenerierung: nach 22 kg Einspeisungsgemisch, Viskositätsabfall von 22,5 mm²/s auf 17,9 mm²/s; nach Regenerierung 1 ist Viskositätsanstieg auf 22–28,6 mm²/s zu verzeichnen, danach starker Abfall nach nur 4,5 kg bzw. 4,8 l Einspeisungsgemisch auf 11,7 mm²/s.
• R2 zweite Regenerierung: nach zweiter Regenerierung ist Viskositätsanstieg zu verzeichnen, mit 18,3 mm²/s ist dieser geringer und nach 3,4 kg bzw. 3,7 l fällt die Viskosität auf 11,5 mm²/s ab.
• R3 dritte Regenerierung: die höhere Temperatur bei Regenerierung 3 bewirkt, dass nach der Regenerierung wiederum ein Viskositätsanstieg auf 21,9 mm²/s möglich ist aber auch hier nach nur 4,2 kg bzw. 4,5 l die Viskosität auf 15,1 mm²/s sinkt.
• R4 vierte Regenerierung: höhere Temperatur und Behandlungsdauer führen nicht dazu, dass die Katalysatoraktivität auf das erforderliche Niveau gebracht wird. Nach anfänglich 22,5 mm²/s fällt die Viskosität nach nur 1,9 kg bzw. 2 l auf 16,9 mm²/s.

Experiments for regeneration with nitrogen:
R1: 21 h / 100 l / h nitrogen / room temperature
R2: 42 h / 100 l / h nitrogen / room temperature
R3: 8 h / 100 l / h nitrogen / 40 ° C
R4: 25 h / 100 l / h nitrogen / 40 ° C
All steps were carried out in succession, ie, when the viscosity dropped, an attempt was made to activate the catalyst in a new way.

• R1 first regeneration: after 22 kg feed mixture, viscosity drop from 22.5 mm ² / s to 17.9 mm ² / s; After regeneration 1, the viscosity increased to 22-28.6 mm ² / s, followed by a sharp drop after only 4.5 kg or 4.8 l feed mixture to 11.7 mm ² / s.
• R2 second regeneration: after the second regeneration, the increase in viscosity is noticeable, at 18.3 mm ² / s this is lower and after 3.4 kg or 3.7 l the viscosity drops to 11.5 mm ² / s.
• R3 third regeneration: the higher temperature during regeneration 3 causes after the regeneration in turn a viscosity increase to 21.9 mm ² / s is possible but also after only 4.2 kg or 4.5 l the viscosity to 15.1 mm ² / s decreases.
• R4 fourth regeneration: higher temperature and treatment time do not cause the catalyst activity to be brought to the required level. After initially 22.5 mm ² / s, the viscosity drops to 16.9 mm ² / s after only 1.9 kg or 2 l.

Example 2

Equilibrierreaktor:

Ø = 2.8 cm, h = 60 cm, double-jacket pipe, heatable.

In these Equilibrierreaktor 60 g of an ion exchange resin based on polystyrene functionalised with sulfonic acid groups in the form of spheres (commercially available (under the name Purolite ^® CT269DR at Purolite Germany) GmbH) loosely filled. Subsequently, the catalyst is heated to 80 ° C and gassed from below for a period of 2 hours with nitrogen in an amount of 100 l / h. Using the oven method, a weight loss corresponding to the escaping water quantity of 1.95% was determined. Thus, the catalyst contains 0.85% water.

The feed mixture E1 and nitrogen are now fed into the tube reactor below. In the feed mixture E1, this takes place in an amount of 150 to 155 ml / h with the aid of a membrane metering pump. Nitrogen is blown in at a rate of 20 l / h. The reaction temperature is 40 ° C.

At the top of the tubular reactor, the equilibrated product mixture is obtained by continuous overflow with retention of the catalyst by means of filter cloth and continuously supplied to the distillation by distillation. In the bottom, predominantly linear siloxanes can be isolated as the target product.

The equilibration catalyst is still active after 15 kg or 16.1 l of feed mixture. The viscosity is very good at an average of 24 mm ² / s. The experiment is stopped at this level because it has the same tendency as in Example 1. The drying of the catalyst at 80 ° C is very effective.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2152270 [0002]
• DE 10311724 A1 [0002]
• US 6534614 [0002]
• DE 102008041601 [0002]
• DE 102005001039 A1 [0002]
• WO 2010/074831 A1 [0002, 0002]
• DE 102008042181 A1 [0002]
• EP 1367079 [0003]
• US 2004/0176561 A1 [0004]

Cited non-patent literature

• DIN 53015 [0047]

Claims (10)

A process for the preparation of organopolysiloxanes by equilibration reaction in which low molecular weight organosiloxanes are contacted with ion exchange resin particles which are fluidized with inert gas and allowed to react. Process according to Claim 1, characterized in that the low molecular weight siloxanes to be equilibrated are linear, cyclic or branched siloxanes having 2 to 100 silicon atoms. Process according to Claim 1 or 2, characterized in that the siloxanes used are those obtainable by hydrolysis or condensation of chlorosilanes of the formula R _a SiH _b Cl _4-ab (I), wherein R may be the same or different and is a monovalent, optionally substituted hydrocarbon radical, a is 1, 2 or 3 and b is 0 or 1, with the proviso that the sum a + b is less than or equal to 3. Method according to one or more of claims 1 to 3, characterized in that it is the inert gas is nitrogen. Method according to one or more of claims 1 to 4, characterized in that it is carried out continuously. Method according to one or more of claims 1 to 5, characterized in that it is carried out in a tube reactor. A method according to claim 6, characterized in that the length of the reactor by a factor of 20 to 30 is greater than its diameter. Method according to one or more of claims 1 to 7, characterized in that before starting the Equilbrierreaktors the reactor temperature and the amount of inert gas are briefly increased significantly (start-up process). Method according to one or more of claims 1 to 8, characterized in that silanes of the formula (I) are reacted with water, optionally in the presence of a water-insoluble solvent, then distilled and from the distillate partially or completely the water is removed and the thus obtained Siloxangemisch with ion exchange resin particles which are fluidized with inert gas, brought into contact and allowed to react and the equilibrated product mixture is then supplied to the distillation by distillation. Method according to one or more of claims 1 to 9, characterized in that silanes of the formula (I) are reacted with water, optionally in the presence of a water-insoluble solvent, then distilled and from the distillate partially or completely the water is removed and the thus obtained siloxane mixture with ion exchange resin particles which are fluidized with inert gas, brought into contact and allowed to react and the equilibrated product mixture is fed to the hydrolyzate directly after the hydrolysis to introduce it homogeneously into the hydrolyzate, leaving after the equilibration remaining cycles or low molecular weight siloxanes be separated in the subsequent to the hydrolysis distillation together with the low molecular weight organosiloxanes of the hydrolyzate.