Method for preparing branched organopolysiloxanes

Abstract

The present invention relates to a compound having a glass transition temperature (Tg) greater than 0° C. and having the general formula (I): R a Si(OR 1 ) b O (4-a-b) / 2 (In the formula, R, R 1 , a and b are as defined in claim 1. A method for the preparation of branched organopolysiloxanes O comprising units of the general formula (II): R n Si(OR 1 ) 4-n (Wherein, n, R and R 1 is as defined in claim 1, in which in not more than 20 mol % of the silanes of general formula (II), all R groups are C1-C2 hydrocarbon groups, and R 1 is a methyl group, and up to 10 moles of further alkoxy- and / or hydroxy-functional organopolysiloxanes or alkoxy- and / or hydroxy-functional silanes are present per 100 moles of silane of general formula (II). The present invention relates to a process for the preparation of branched organopolysiloxanes O, which comprises reacting a silane of general formula (II) with water, a catalytic amount of an acid catalyst K, and optionally an alcohol A, with the proviso that no solvent other than the alcohol A is added during the entire process, the alcohol A being selected from methanol, ethanol, and mixtures of methanol and ethanol, and up to 50 parts by weight of further alkanols may be present per 100 parts by weight of methanol and ethanol.

Description

[Technical field]

[0001] The present invention relates to a method for preparing branched organopolysiloxanes having a glass transition temperature (Tg) above 0°C from alkoxysilanes. [Background technology]

[0002] Methods for preparing solid organopolysiloxanes, also called solid silicone resins, have long been in the prior art.

[0003] EP 0 927 734 B1 describes the multi-step preparation of solid resins from alkoxysilanes catalyzed by hydrochloric acid in the presence of a water-immiscible solvent.

[0004] DE 102005003899 describes the preparation of resins by reacting chlorosilanes with alcohols and water in a one-step continuous process. A non-reactive solvent is required for the preparation of solid resins.

[0005] US6552151B1 claims a solid resin with a Tg above 60° C. and a specific silanol content. The example is prepared batchwise from ethoxysilane, hydrochloric acid and water, and worked up with an organic solvent. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] EP0927734B1 publication [Patent Document 2] DE102005003899 publication [Patent Document 3] US6552151B1 publication Summary of the Invention [Means for solving the problem]

[0007] The present invention relates to a polymer having a glass transition temperature (Tg) greater than 0° C. and having the general formula (I): R a Si(OR 1 ) b O (4-a-b) / 2 (I) (In the formula, R is an unsubstituted or heteroatom-substituted hydrolytically stable C1-C18 hydrocarbon group; R 1 is hydrogen or a C1-C4 hydrocarbon group, a and b are 0, 1, 2, or 3; However, a+b≦3; a in at least 70 mol %, preferably at least 80 mol %, particularly preferably at least 90 mol % of all units of the general formula (I) has the value 1, a, averaged over all units of the general formula (I), has an average value of 0.7 to 1.3, preferably 0.8 to 1.2, and particularly preferably 0.9 to 1.1; b, averaged over all units of the general formula (I), has an average value of 0.10 to 1.0, preferably 0.15 to 0.9, and particularly preferably 0.20 to 0.8; All R 1 At least 70 mol %, preferably at least 80 mol %, particularly preferably at least 90 mol % are hydrogen, methyl groups, or ethyl groups. A process for the preparation of branched organopolysiloxanes O comprising units of General formula (II): R n Si(OR 1 ) 4-n (II) (In the formula, n can have the value 0, 1, 2, or 3; n in at least 70 mol % of the silanes of general formula (II) has the value 1, R and R 1 has the definition given for general formula (I) above, In at most 20 mol % of the silanes of general formula (II), all radicals R are C1-C2 hydrocarbon radicals, R 1is a methyl group, At most 10 mol of further alkoxy- and / or hydroxy-functional organopolysiloxanes or alkoxy- and / or hydroxy-functional silanes are present per 100 mol of silane of general formula (II). with water, a catalytic amount of an acid catalyst K, and optionally an alcohol A, However, no solvents other than alcohol A were used throughout the entire process. in which the alcohol A is selected from methanol, ethanol or a mixture of methanol and ethanol, and in each case up to 50 parts by weight of a further alkanol may be present, based on 100 parts by weight of methanol and ethanol, A method for preparing a branched organopolysiloxane O is provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] in which the hydrolysis and condensation of the alkoxysilanes of general formula (II) is carried out through reaction with water, a catalytic amount of an acid catalyst K, optionally an alcohol A, and optionally further alkoxy- and / or hydroxy-functional organopolysiloxanes or alkoxy- and / or hydroxy-functional silanes, final product A branched organopolysiloxane is obtained having the desired degree of condensation, where A is the alcohol A used and optionally further alkanols. No solvents are used throughout the entire process, except for at most 3% by weight, in particular at most 1% by weight, of conventional denaturants such as heptane and methyl ethyl ketone in ethanol.

[0009] Said method has in particular the following advantageous properties: Viscous or solid organopolysiloxanes can be prepared in an economically viable manner; - Organopolysiloxanes of a consistent composition can be prepared reproducibly from alkoxysilanes or mixtures of different alkoxysilanes. No inert organic solvents are used, and the reaction mixture contains only the organic components required as reactants. -No wastewater phase is produced; -Products with very low residual acid content can be obtained. The ability to control the alkoxy and hydroxy content makes it suitable for providing both viscous and solid organopolysiloxanes in a robust procedure. Recovery of released alcohol is at least 95%.

[0010] No other solvent is necessary besides the alcohol A. As long as the reaction medium after the addition of water is homogeneous, further solvents can be used, in particular solvents with a boiling point in the range of the alcohol used, but it is particularly preferred not to use other solvents.

[0011] The acid catalyst is deactivated after the reaction by a suitable method.

[0012] The branched organopolysiloxane O is then purified / worked up by devolatilization, which removes volatile components to obtain a pure final form. The devolatilization can be varied as desired, in which case the procedures are all within the scope of the known prior art, including, for example, distillation. Further examples of suitable variations are described in more detail below.

[0013] When alcohols are used, preference is given to hydrocarbon compounds having alcoholic hydroxy groups that can be used for the preparation of alkoxysilanes or organopolysiloxanes by reaction of chlorosilanes with alcohol and optionally water. Preference is given to alkanols and ether-oxygen-substituted alkanols having 1 to 6 carbon atoms, such as methanol, ethanol, n- or isopropanol, 2-methoxyethanol, n-butanol or n-hexanol. Particular preference is given to methanol, ethanol, isopropanol and butanol, in particular methanol and ethanol. It is also possible to use mixtures of different alcohols, which can be optionally homogenized in a short mixing section before being fed to the respective reaction unit. The ethanol may contain conventional modifiers, such as methyl ethyl ketone, heptane, petroleum ether or cyclohexane.

[0014] Selected examples of hydrocarbon radicals R are alkyl radicals, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl radicals such as n-hexyl, heptyl radicals such as n-heptyl, octyl radicals such as n-octyl, isooctyl radicals such as 2,2,4-trimethylpentyl, nonyl radicals such as n-nonyl, decyl radicals such as n-decyl, dodecyl radicals such as n-dodecyl, octadecyl radicals such as n-octadecyl, cycloalkyl radicals such as cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl, alkenyl radicals such as vinyl, aryl radicals such as phenyl, naphthyl, anthryl and phenanthryl, alkaryl radicals such as tolyl, xylyl and ethylphenyl, aralkyl radicals such as benzyl and β-phenylethyl. Particularly preferred hydrocarbon radicals R are methyl, vinyl, n-propyl, octyl and phenyl radicals.

[0015] The silanes of general formula (II) can be used both as pure silanes and as mixtures of different silanes of general formula (II). Furthermore, the partial condensate can also be used as a solution in an alcohol.

[0016] Preferably, n has the value 1 for at least 70 mol %, preferably at least 80 mol %, particularly preferably at least 90 mol % of all units of general formula (II).

[0017] The organopolysiloxane O preferably comprises at least 90 mol %, particularly preferably at least 95 mol %, in particular at least 99 mol %, of units of the general formula (I).

[0018] Preferably, in at most 15 mol %, in particular at most 10 mol %, of the silanes of general formula (II), all radicals R are C1-C2 hydrocarbon radicals, R 1 is a methyl group.

[0019] Preferably, at most 5 mol, particularly preferably at most 2 mol, in particular at most 1 mol, and very particularly preferably none, of further alkoxy- and / or hydroxy-functional organopolysiloxanes or alkoxy- and / or hydroxy-functional silanes are present per 100 mol of silanes of the general formula (II).

[0020] The water used is preferably partially demineralized water, fully demineralized water, distilled water or (multiple) double distilled water, water for medical or pharmaceutical purposes, particularly preferably partially demineralized water and fully demineralized water.

[0021] The water used according to the invention preferably has a conductivity of at most 50 μS / cm at 25° C. and 1010 hPa. The water used according to the invention is preferably air-saturated and is colorless and transparent.

[0022] The acid catalyst K used is preferably hydrochloric acid or a compound which forms hydrochloric acid under the reaction conditions, such as, for example, chlorosilanes, carbonyl chlorides, chlorides of elements of transition groups 3-8 or main groups 3-5, etc.

[0023] In the silane of the general formula (II), R 1 Preferably, 0.01 to 1 mol, particularly 0.01 to 0.5 mol of hydrochloric acid or a compound capable of forming hydrochloric acid is used per 100 mol.

[0024] In the silane of the general formula (II), R 1 Preferably, 30 to 150 mol, particularly 40 to 100 mol of water is used per 100 mol.

[0025] The reaction preferably takes from 10 minutes to a day, particularly from 30 minutes to 6 hours.

[0026] The process is preferably carried out discontinuously, i.e. batchwise.

[0027] After the reaction is complete, the acid catalyst K is inactivated by a suitable method, such as neutralization with alcoholic sodium hydroxide solution, sodium methoxide solution or sodium ethoxide solution, alcoholic potassium hydroxide solution, or removal of chlorine atoms with a basic ion exchanger, for example a weakly basic polystyrene resin such as Purolite® A103Plus from Purolite or Amberlyst® A21 from DuPont. Before further work-up and optional storage, the residual hydrochloric acid content, titratable with ethanolic potassium hydroxide solution on tetrabromophenolphthalein ethyl ester, is preferably 100-0 ppm, particularly preferably 50-2 ppm, in particular 30-5 ppm, in each case at 25° C.

[0028] Deactivated Silicone Resin Solution is at most 100 mPa·s, in particular at most 80 mPa·s and in particular at most 50 mPa·s, in each case at 25° C.

[0029] After inactivation, the inactivated Silicone Resin Solutioncan be purified / worked up by devolatilization, which removes volatile components and gives the organopolysiloxane O in pure final form. The devolatilization can be varied as desired, all procedures within the known prior art, including, for example, distillation. Further examples of suitable variations are described in more detail below.

[0030] The above Silicone Resin Solution can be purified by treatment with an adsorbent such as activated carbon, silica gel, cross-linked polystyrene resin, or molecular sieve. Silicone Resin Solution is preferably treated with an adsorbent prior to workup.

[0031] The organopolysiloxanes O preferably have an average molecular weight Mw in the range of 500 to 20,000 g / mol (weight average) and a polydispersity (PD) of at most 20. Particularly preferably, they have an Mw of 600 to 15,000 g / mol and a polydispersity of 18. Very particularly preferably, they have an Mw of 700 to 10,000 g / mol and a polydispersity of 15. In particular, they have an Mw of 700 to 8,000 g / mol and a polydispersity of 13. The organopolysiloxanes O are highly viscous or solid at room temperature, so that their melting temperature can cover a wide temperature range.

[0032] The organopolysiloxane O preferably has a glass transition temperature (Tg) of 5°C to 100°C, particularly preferably 10°C to 80°C, and particularly preferably 20°C to 70°C.

[0033] The organopolysiloxanes O prepared by the process according to the invention or preparations obtained therefrom are suitable for use in anticorrosive preparations, in particular for the purpose of preventing corrosion at high temperatures. Apart from the hot corrosion protection purpose, the organopolysiloxanes O or preparations obtained therefrom can also be used to protect reinforcing steel bars in reinforced concrete, where they can be used either in pure form or as preparations. The corrosion-inhibiting effect in reinforced concrete is achieved both when the organopolysiloxanes O or preparations containing them are introduced into the concrete mix before the concrete is cast and hardened, and also when they are applied directly to the surface of the concrete after the concrete has hardened.

[0034] The organopolysiloxanes O or their preparations can be used as binders for the production of artificial stones for indoor and outdoor use. Said organopolysiloxane O or its preparations can be used to manufacture pre-impregnated fibres, known as prepregs.

[0035] In addition to the purpose of preventing corrosion of metals, the organopolysiloxanes O also have further properties in the preparations or in the solids or films obtained therefrom: Control of electrical conductivity and electrical resistance Control of the leveling properties of the formulation Controlling the gloss of wet or cured films and objects -Improved weather resistance -Improved chemical resistance -Improved color stability Reduced tendency to choke -Reducing or improving static and sliding friction on solids and films Stabilization or destabilization of foam in preparations Improved adhesive properties of preparations Controlling the wetting and dispersion behavior of fillers and pigments Control of the rheological properties of the formulation Control of mechanical properties of solids or films such as flexibility, scratch resistance, elasticity, extensibility, bending strength, breaking behavior, rebound behavior, hardness, density, tear propagation resistance, compression set, behavior at different temperatures, expansion coefficient, abrasion resistance, as well as further properties such as thermal conductivity, flammability, gas permeability, resistance to water vapor, hot air, chemicals, weathering and radiation, sterilizability, etc. Control of electrical properties such as dielectric loss factor, dielectric strength, dielectric constant, tracking resistance, arc resistance, surface resistance, and specific insulation resistance Flexibility, scratch resistance, elasticity, extensibility, bending strength, breaking behavior, rebound behavior, hardness, density, tear propagation resistance, compression set, behavior at different temperatures of solids and films can be used to adjust the

[0036] Examples of applications in which the organopolysiloxanes O can be used to adjust the above-specified properties include the production of coating materials and impregnations and coatings and coverings obtained therefrom on substrates such as metal, glass, wood, mineral substrates, textiles, synthetic and natural fibers, plastics such as leather, films, moldings, etc., for the production of carpets, flooring, or other goods that can be produced from textiles. With the appropriate selection of the components of the formulation, the organopolysiloxanes O can also be used in the formulation as additives for the purposes of defoaming, promoting leveling, hydrophobing, hydrophilizing, dispersing fillers and pigments, wetting fillers and pigments, wetting substrates, promoting surface smoothness, reducing the static and sliding friction of the surface of the cured compound obtained from the additive formulation. The organopolysiloxanes O can also be incorporated into the elastomeric composition in dissolved, solid or cured solid form. In this case, they can be used for reinforcement purposes or to improve other use properties such as transparency, heat resistance, yellowing tendency, weather resistance control, etc.

[0037] All symbols in the above formulae have mutually independent definitions. In all formulae, the silicon atom is tetravalent.

[0038] In this document, materials are characterized by reporting data obtained by instrumental analysis. The underlying measurements are performed according to publicly available standards or are determined by specially developed methods. For clarity of the discussion, the methods used are specified here.

[0039] (consistency) The solid test substances are placed in chunks in transparent glass bottles and stored at 25° C. and 1013 mbar standard pressure for 24 hours, after which their appearance and adhesion are evaluated.

[0040] (soluble in acetone) 10 ml of acetone is added to 1 g of the test substance and stirred for 1 hour at 25° C. and 1013 mbar standard pressure, after which it is visually assessed whether the substance has completely dissolved.

[0041] (molecular composition) The molecular composition was determined by nuclear magnetic resonance spectroscopy (see ASTM E 386:High-resolution nuclear magnetic resonance (NMR) spectroscopy: terms and symbols). 1 H nucleus and 29 This is done by measuring the Si nucleus.

[0042] [ 1 Explanation of H-NMR measurements] Solvent: CDCl3, 99.8%d Sample concentration: Approximately 50mg / 1ml CDCl3 in a 5mm NMR tube Measured without adding TMS and referenced to the spectrum of residual CHCl3 in CDCl3 at 7.24 ppm Spectrometer: Bruker Avance I 500 or Bruker Avance HD 500 Probe: 5mm BBO probe or SMART probe (Bruker) Measurement parameters: Pulprog=zg30 TD=64k NS=64 or 128 (depending on probe sensitivity) SW=20.6ppm AQ=3.17s D1=5s SFO1=500.13MHz O1=6.175ppm Processing parameters: SI=32k WDW=EM LB=0.3Hz Depending on the type of spectrometer used, individual adjustments of the measurement parameters may be necessary.

[0043] [ 29 Explanation of Si-NMR measurement] Solvent: C6D6 99.8%d / CCl4 1:1 v / v containing 1% by mass of Cr(acac)3 as a relaxation agent Sample concentration: Approximately 2g / 1.5ml solvent in a 10mm NMR tube Spectrometer:Bruker Avance 300 Probe: 10mm 1H / 13C / 15N / 29Si glass-free QNP probe (Bruker) Measurement parameters: Pulprog=zgig60 TD=64k NS=1024 (depending on probe sensitivity) SW=200ppm AQ=2.75s D1=4s SFO1=300.13MHz O1=-50ppm Processing parameters: SI=64k WDW=EM LB=0.3Hz Depending on the type of spectrometer used, individual adjustments of the measurement parameters may be necessary.

[0044] (molecular weight distribution) In the context of the present invention, the number-average molar mass Mn and the weight-average molar mass Mw are determined by size-exclusion chromatography (SEC) according to DIN 55672-1 against polystyrene standards using a RI (refractive index detector) on a Styragel HR3-HR4-HR5-HR5 column set from Waters Corp., USA, with an injection volume of 20 μl. The eluent used is analytical grade toluene >99.9% available from Merck KGaA, Darmstadt, Germany. The analysis is carried out at a column temperature of 45° C. The polydispersity (PD) is the quotient Mw / Mn.

[0045] (glass transition temperature) The glass transition temperature Tg is measured by DSC (differential scanning calorimetry) using a Mettler Toledo DSC1 / 500 dynamic scanning calorimeter (module name: DSC1_1448) in an open crucible with a sample weight of 10.5 mg and a constant nitrogen flow of 50 ml / min in the following temperature regime: Temperature control at 25°C for 5 minutes, Cool to -150℃ at a rate of 20K / min. Temperature control at -150℃ for 8 minutes, Heat up to 100°C at a heating rate of 10K / min. Temperature control at 100℃ for 15 minutes, Cool to -150℃ at a rate of 20K / min. Temperature control at -150℃ for 8 minutes, Heat up to 160°C at a heating rate of 10K / min. Cool to -150℃ at a rate of 20K / min. Temperature control at -150℃ for 8 minutes, Heat up to 160°C at a heating rate of 10K / min.

[0046] The glass transition temperature was measured using METTLER TOLEDO's STAR e The measurements were taken between the first and second heating steps to 160° C. using software version 16.20. The software defines Tg as the intersection point between the measurement curve and the bisector of the baseline around the glass transition temperature, and in the examples, the arithmetic mean of the two values ​​is rounded to an integer. EXAMPLES

[0047] The following examples illustrate the preparation methods according to the invention, but should not be construed as limiting. All percentages are by weight unless otherwise specified. All operations are carried out at room temperature of about 25° C. and at standard pressure (1.013 bar) unless otherwise specified. The equipment is commercially available laboratory equipment of the type commercially supplied by a number of equipment manufacturers. Ph is a phenyl group (C6H5-). Vin is the vinyl group (CH2=CH-). Me is a methyl group (CH3-). Therefore, Me2 is two methyl groups.

[0048] Example 1: Preparation method according to the present invention 157 g of methyltriethoxysilane and 58 g of vinyltriethoxysilane are initially placed in a 1 L glass flask equipped with a reflux condenser, a dropping funnel and a magnetic stirrer, mixed with a mixture of 0.4 g of hydrochloric acid (20%) and 48 g of water over 15 minutes and stirred at reflux for 3 hours. The condensed hydrochloric acidic organopolysiloxane solution thus formed is neutralized with sodium methoxide solution (25% in methanol) until the hydrochloric acid value is 15 ppm. This alcoholic organopolysiloxane solution is then distilled to give a cloudy white solid which dissolves completely in acetone and is defined by product parameters such as melting point, residual alkoxy content, molecular weight distribution, etc. In a typical example, the following analytical data is obtained: 29 Molecular composition by Si-NMR: MeSi(OH)O 2 / 2 +MeSi(OEt)O 2 / 2 : 23.0mol%, MeSiO 3 / 2 : 52.6mol%, VinSi(OH)O 2 / 2 +VinSi(OEt)O 2 / 2 : 10.0mol%, VinSiO3 / 2 : 14.4mol% 1 Composition by H-NMR: EtO 1 / 2 Content: 5.9% by mass, H.O. 1 / 2 Content: 1.6% by mass, VinSiO 3 / 2 Content: 26.0% by mass, MeSiO 3 / 2 Content: 66.5% by mass Further product parameters: Consistency: Tack-free mass Tg: 40℃ Mw: 840g / mol Mn: 300g / mol PD:2.8

[0049] Example 2: Preparation method according to the present invention The procedure of Example 1 is repeated, except that 54 g of water is used, and therefore stirring at reflux is carried out for only 1 hour. A cloudy white solid is obtained, which dissolves completely in acetone. The following analytical data are obtained: 29 Molecular composition by Si-NMR: MeSi(OH)O 2 / 2 +MeSi(OEt)O 2 / 2 : 23.8mol%, MeSiO 3 / 2 : 51.9mol%, VinSi(OH)O 2 / 2 +VinSi(OEt)O 2 / 2 : 9.5mol%, VinSiO 3 / 2 : 14.8mol% 1 Composition by H-NMR: EtO 1 / 2 Content: 6.0% by mass, H.O. 1 / 2 Content: 1.5% by mass, VinSiO 3 / 2 Content: 25.5% by mass, MeSiO 3 / 2 Content: 67.0% by mass Further product parameters: Consistency: Tack-free mass Tg: 36℃ Mw: 850g / mol Mn: 310g / mol PD:2.7

[0050] Example 3: Preparation method according to the present invention 144 g of phenyltriethoxysilane, 75 g of methyltriethoxysilane and 11 g of methylvinyldimethoxysilane are initially placed in a 1 L glass flask equipped with a reflux condenser, a dropping funnel and a magnetic stirrer, mixed with a mixture of 0.4 g of hydrochloric acid (20%) and 52 g of water over 15 minutes and stirred at reflux for 3 hours. The condensed hydrochloric acidic organopolysiloxane solution thus formed is neutralized with sodium methoxide solution (25% in methanol) until the hydrochloric acid value is 15 ppm. This alcoholic organopolysiloxane solution is then distilled to give a clear solid which is completely soluble in acetone and is defined by product parameters such as melting point, residual alkoxy content, etc. In a typical example, the following analytical data is obtained: 29 Molecular composition by Si-NMR: MeSi(OH)O 2 / 2 +MeSi(OEt)O 2 / 2 : 12.4mol%, MeSiO 3 / 2 : 27.4mol%, PhSi(OH)O 2 / 2 +PhSi(OEt)O 2 / 2 : 32.7mol%, PhSiO 3 / 2 : 20.7mol%, MeVinSiO 2 / 2 :6.8mol% 1 Composition by H-NMR: EtO 1 / 2 Content: 3.0% by mass, H.O. 1 / 2 Content: 1.0% by mass, PhSiO 3 / 2Content: 67.0% by mass, MeSiO 3 / 2 Content: 23.6% by mass, MeVinSiO 2 / 2 Content: 5.4% by mass Further product parameters: Consistency: Tack-free mass Tg: 35℃

[0051] Example 4: Preparation method according to the present invention 218 g of phenyltrimethoxysilane are initially placed in a 1 liter glass flask equipped with a reflux condenser, a dropping funnel and a magnetic stirrer, mixed with a mixture of 0.4 g of hydrochloric acid (20%) and 50 g of water over 15 minutes and stirred at reflux for 3 hours. The condensed hydrochloric acidic organopolysiloxane solution thus formed is neutralized with sodium methoxide solution (25% in methanol) until the hydrochloric acid value is 15 ppm. This alcoholic organopolysiloxane solution is then distilled to give a clear solid which is completely soluble in acetone and is defined by product parameters such as melting point and residual alkoxy content. In a typical example, the following analytical data is obtained: 29 Molecular composition by Si-NMR: PhSi(OH)O 1 / 2 +PhSi(OMe)(OH)O 1 / 2 : 1.8mol%, PhSi(OH)O 2 / 2 +PhSi(OMe)O 2 / 2 : 60.0mol%, PhSiO 3 / 2 :38.2mol% 1 Composition by H-NMR: MeO 1 / 2 Content: 1.7% by mass, H.O. 1 / 2 Content: 2.0% by mass, PhSiO 3 / 2 Content: 96.3% by mass, Further product parameters: Consistency: Tack-free mass Tg: 67℃

[0052] Comparative Example 1: Preparation method not according to the present invention 120 g of methyltrimethoxysilane and 45 g of vinyltrimethoxysilane are initially placed in a 1 l glass flask equipped with a reflux condenser, a dropping funnel and a KPG stirrer (KPG-Ruhrer), mixed over 15 minutes with a mixture of 0.25 g of hydrochloric acid (20%) and 40 g of water and stirred at reflux for 2 hours. The condensed hydrochloric acidic organopolysiloxane solution thus formed is neutralized with sodium methoxide solution (25% in methanol) until the hydrochloric acid value is 15 ppm. This alcoholic organopolysiloxane solution was then distilled to give a solid which was not completely soluble in acetone.

Claims

1. 0° C. and having a glass transition temperature (Tg) greater than 0° C. and having the general formula (I): R ａ Si(OR １ ) ｂ O （４－ａ－ｂ）／２ (I) (In the formula, R is an unsubstituted or heteroatom-substituted hydrolytically stable C1-C18 hydrocarbon group; R １ is hydrogen or a C1-C4 hydrocarbon group, a and b are 0, 1, 2, or 3, with the proviso that a+b is ≦3; a in at least 70 mol % of all units of the general formula (I) has the value 1, a, averaged over all units of the general formula (I), has an average value of 0.7 to 1.3; b, averaged over all units of the general formula (I), has an average value of 0.10 to 1.0; All groups R １ At least 70 mol % of the are hydrogen, methyl groups, or ethyl groups. A process for the preparation of a branched organopolysiloxane O comprising units of General formula (II): R ｎ Si (OR １ ) ４－ｎ (II) (In the formula, n can have the value 0, 1, 2 or 3; n in at least 70 mol % of the silanes of general formula (II) has the value 1, R and R １ has the definition given for general formula (I) above, In at most 20 mol % of the silanes of general formula (II), all radicals R are C1-C2 hydrocarbon radicals, R １ is a methyl group, At most 10 mol of further alkoxy- and / or hydroxy-functional organopolysiloxanes or alkoxy- and / or hydroxy-functional silanes are present per 100 mol of silane of general formula (II). with water, a catalytic amount of an acid catalyst K, and optionally an alcohol A, However, no solvent other than alcohol A was used throughout the entire process. in which the alcohol A is selected from among methanol, ethanol or a mixture of methanol and ethanol, and in each case up to 50 parts by weight of a further alkanol may be present, based on 100 parts by weight of methanol and ethanol, Method for preparing branched organopolysiloxane O.

2. 2. The process according to claim 1, wherein the hydrocarbon group R is selected from methyl, vinyl, n-propyl, octyl and phenyl groups.

3. 3. A process according to claim 1 or 2, wherein n has the value 1 in at least 90 mol % of all units of general formula (II).

4. 4. The process according to claim 1, wherein the acid catalyst K used is hydrochloric acid or a compound which forms hydrochloric acid under the reaction conditions.

5. 5. The process according to claim 1, wherein the organopolysiloxane O has a glass transition temperature (Tg) of from 10° C. to 80° C.

6. The process according to any one of claims 1 to 5, which is carried out discontinuously.

7. 7. The process according to claim 1, wherein after the reaction is complete, the acid catalyst K is neutralized with an alcoholic sodium hydroxide solution, a sodium methoxide solution, a sodium ethoxide solution or a potassium hydroxide solution.

8. 7. The process according to claim 1, wherein after completion of the reaction, the acidic catalyst K is neutralized with a basic ion exchanger.

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