Process for preparing organopolysiloxane resins
阅读说明：本技术 用于制备有机聚硅氧烷树脂的方法 (Process for preparing organopolysiloxane resins ) 是由 K·科普勒 E·图姆泽 于 2017-05-16 设计创作，主要内容包括：本发明涉及通过有机氯硅烷的水解和缩合来制备有机聚硅氧烷树脂的多阶段方法。(The present invention relates to a multistage process for preparing organopolysiloxane resins by hydrolysis and condensation of organochlorosilanes.)
1. A process for preparing organopolysiloxane resins, wherein
In a first continuous stepReacting organochlorosilanes with from 0.10 to 0.75mol of water per mole of hydrolysable chlorine and with from 0.3 to 1.0mol of alcohol per mole of hydrolysable chlorine in a vertical circulation reactor, the temperature in the circulation reactor being regulated by means of a heating assembly on the rising section of the tubular reactor, wherein the molar ratio of water to alcohol is from 0.10 to 2.5, wherein the ratio of aqueous alcohol to silane mixture is regulated within said range so that the fraction of the alcohol phase in the product mixture of this first step is from 0.1 to 50% by weight, wherein the heating assembly captures the temperature of the reaction medium to a temperature as a regulated variable and, in a sense calibrated with said controlled variable, is regulated with an accuracy of 5 ℃ compared with a fixed temperature as a controlled variable within the range of from 20 to 60 ℃, and the amount of alcohol used in this first step is reduced to such an extent that the fraction of the alcohol phase in the overall product mixture of the first step is from 0.1 to 40% by weight,
wherein the aqueous alcohol used herein may comprise up to 31 wt% dissolved HCl and up to 5 wt% water-insoluble organic solvent,
in the second stepAdding a water-insoluble organic solvent having a density of less than 0.95kg/l to the reaction mixture obtained in the first step and adding water in an amount of 1.5 to 5mol of water per mol of Si component and, after the end of the metering in the second step, separating off an alcoholic HCl phase and
in the third stepOptionally adding to the silicone phase of the second step a silicone phase having a density of less than 0.95kg/lA water-insoluble organic solvent and water is added in an amount of 5 to 200mol of water per mol of the Si component, and
in the fourth stepAnd separating the aqueous phase formed from the silicone phase after the addition of water in said third step is complete.
2. The method according to claim 1, characterized in that in the second step, a water-insoluble organic solvent is added in an amount of 0.5 to 50mol based on 1 mol of the Si component.
3. The method according to claim 1 or 2, characterized in that in the second step, a water-insoluble organic solvent is added in an amount of 1 to 30mol based on 1 mol of the Si component.
4. A process according to any one of claims 1 to 3, characterised in that in the second step, additionally 0.1 to 0.5mol of alcohol, in each case based on 1 mol of silicon component, are metered in.
Background
Processes for preparing organopolysiloxane resins have been known for a long time. Methods for reacting organochlorosilanes with water and alcohols are likewise known. In the prior art, for example, EP2491071B1 describes a cost-optimized method. The preparation takes place in three steps in order to better control the reaction, since uncontrolled reaction processes rapidly lead to gelling of the reaction product, which is therefore unusable. The first step, i.e. the partial alkoxylation of the organochlorosilanes, takes place in this case continuously in a vertical circulation reactor, the temperature of which is regulated in the circulation reactor by means of a heating assembly on the rising part of the tubular reactor. Due to this temperature regulation of the reaction, it is possible to produce silicone resins with the same end product properties despite the greatly reduced amount of ethanol. In the second step, the continuously produced reaction product from the first step ("partial alkoxylate") is hydrolyzed discontinuously by adding water in the presence of a water immiscible solvent. Hydrochloric acid is formed in this procedure, and therefore, at the end of the operation, in addition to the silicone resin solution, there is a water-alcohol phase, called "sour water", which consists of water, ethanol and hydrochloric acid. This phase is separated in a third step and sent to a distillation ethanol recovery facility. The bottom product (water containing HCl) must be treated with waste water, so its HCl content is lost due to handling.
Object of the Invention
It is therefore an object to provide an improved process for preparing organopolysiloxane resins with lower HCl loss without changing the properties of the final product.
This object is surprisingly achieved by the process of the present invention.
The subject of the present invention is therefore a process for preparing organopolysiloxane resins, in which
In thatIn the first continuous stepIn a vertical loop reactor, which adjusts the temperature in the loop reactor by means of a heating element on the rising section of the tube reactor, reacting organochlorosilanes with 0.10 to 0.75mol of water per mol of hydrolyzable chlorine and with 0.3 to 1.0mol of alcohol per mol of hydrolyzable chlorine, wherein the molar ratio of water to alcohol is 0.10 to 2.5, wherein the ratio of aqueous alcohol to silane mixture is adjusted within the range such that the fraction of the alcohol phase in the product mixture of the first step is 0.1 to 50 wt.%, wherein the heating element captures the temperature of the reaction medium to a temperature as a regulated variable and adjusts it to an accuracy of 5 ℃ in a calibrated sense with the controlled variable, compared to a fixed temperature as a controlled variable within the range of 20 to 60 ℃, and the amount of alcohol used in the first step is reduced to such an extent that the fraction of the alcohol phase in the overall product mixture of the first step is 0.1 to 40 wt.%,
wherein the aqueous alcohol used herein may comprise up to 31 wt% dissolved HCl and up to 5 wt% water-insoluble organic solvent,
in the second stepIn the direction ofAdding a water-insoluble organic solvent having a density of less than 0.95kg/l and adding water in an amount of 1.5 to 5mol of water per mol of Si component to the reaction mixture obtained in the first step, and after the end of the metering in the second step, separating off the alcoholic HCl phase and
in the third stepOptionally adding a water-insoluble organic solvent having a density of less than 0.95kg/l to the siloxane phase of the second step and adding water in an amount of 5 to 200mol water per mol Si component, and
in the fourth stepSeparating the formed aqueous phase from the silicone phase after the end of the water addition in the third step.
The first step is as follows: continuous partial alkoxylation
The organochlorosilanes used in the first step of the process of the invention are preferably compounds of the general formula
RaSiCl4-a (I)，
Wherein R may be the same or different and is a monovalent, SiC-bonded, substituted or unsubstituted hydrocarbon group, and a is 1, 2, 3.
Examples of unsubstituted radicals R are alkyl radicals such as the methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl radical; hexyl radicals, such as the n-hexyl radical; heptyl, such as n-heptyl; octyl groups such as n-octyl and isooctyl groups such as 2,2, 4-trimethylpentyl; nonyl groups, such as n-nonyl; decyl groups such as n-decyl; dodecyl groups such as n-dodecyl; alkenyl groups such as vinyl and allyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and methylcyclohexyl; aryl groups such as phenyl and naphthyl; alkaryl groups such as o-tolyl, m-tolyl, p-tolyl, xylyl, and ethylphenyl; aralkyl groups such as benzyl, alpha-phenylethyl and beta-phenylethyl.
Examples of substituted radicals R are all the radicals mentioned above for R, which can preferably be substituted by mercapto, carboxyl, keto, aryloxy, acryloxy, methacryloxy, hydroxyl and halogen radicals.
The group R preferably comprises a hydrocarbon group having 1 to 8 carbon atoms, more preferably a methyl group.
Examples of silanes of the formula (I) are methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, isooctyltrichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane and methylphenyldichlorosilane.
The silanes used in the process of the invention are preferably liquid at 20 ℃ and at pressures of from 900 to 1100 hPa.
Preference is given to using mixtures of silanes of the formula (I) with at least one organotrichlorosilane.
In the context of the present invention, hydrolyzable chlorine is intended to mean chlorine present in the form of SiCl groups.
In the first step of the process of the invention, the organochlorosilane is mixed with preferably from 0.002 to 0.75mol, more preferably from 0.1 to 0.5mol, of water per mole of hydrolyzable chlorine.
In the first step of the process of the invention, the organochlorosilane is mixed with preferably from 0.1 to 1.5mol, more preferably from 0.3 to 1.0mol, of alcohol per mole of hydrolyzable chlorine.
In the first step of the process of the invention, water is used in a molar ratio with respect to the alcohol of preferably 0.13 to 0.85.
In the process of the present invention, the amount of alcohol used in the first step is preferably reduced to such an extent that the fraction of the alcohol phase in the total product mixture of the first step is preferably from 0 to 50% by weight, from 0.1 to 50% by weight, more preferably from 0 to 40% by weight, from 0.1 to 40% by weight, particularly preferably from 0 to 25% by weight, from 0.1 to 25% by weight, very preferably from 0 to 20% by weight, from 0.1 to 20% by weight, particularly preferably from 0 to 10% by weight, from 0.1 to 10% by weight.
Examples of alcohols which can be used in the first step of the process of the invention are all alcohols which are liquid at a temperature of 20 ℃ and at a pressure of 900 to 1100hPa, such as preferably methanol, ethanol, n-propanol, isopropanol, butanol, pentanol, hexanol, heptanol; methanol, ethanol and butanol and ethanol is particularly preferred.
If desired, in addition to organochlorosilanes, water and alcohols (where the aqueous alcohol used here may contain up to 31% by weight of dissolved HCl and up to 5% by weight of a water-insoluble organic solvent, preferably toluene), further substances may be used in the first step of the process of the invention. Examples of optionally used further substances are alkoxysilanes (such as tetraethoxysilane) or water-insoluble organic solvents (such as toluene), preferably having a density of less than 0.95 kg/l.
In the process of the present invention, the molecular weight of the final product (organopolysiloxane resin) can be controlled by the reaction parameters of the off-gas pressure and the reaction temperature in the first step (alkoxylation step) of the preparation process. The temperature is kept preferably constant in the range from 20 ℃ to 60 ℃, more preferably from 25 ℃ to 50 ℃, very preferably from 25 ℃ to 45 ℃, particularly preferably from 30 ℃ to 40 ℃ by active regulation via the heating assembly. The exhaust gas pressure is preferably maintained in the range of 800 to 2000hPa, more preferably 1000 to 1500hPa, and very preferably 1100 to 1400hPa, by means of a compressor. The accuracy of the temperature adjustment can be set at 5 ℃, preferably at 4.5 ℃,4 ℃, 3.5 ℃, 3 ℃, 2.5 ℃,2 ℃, 1.5 ℃, 1 ℃, and very preferably at 0.5 ℃.
In the first step of the process according to the invention, the organochlorosilane or the mixture of organochlorosilanes is metered continuously into a circulating reactor (equipped with a heating assembly). At the same time, a mixture of water and alcohol is continuously metered in via a further feed line, wherein the water content of the alcohol is preferably in the range from 5 to 30% by weight, more preferably from 8 to 28% by weight, very preferably from 10 to 25% by weight, and wherein the aqueous alcohol used here may contain up to 31% by weight of dissolved HCl and up to 5% by weight of a water-insoluble organic solvent, preferably toluene. Additional substances may optionally be metered in. In this case, the products are alkoxysilanes, alkoxychlorosilanes and their hydrolysis products and condensates, as well as hydrogen chloride, alkyl chlorides and dialkyl ethers. Here, the hydrogen chloride gas obtained in the first step, after passing through a suitable cleaning process, can preferably be reused as a starting material in other processes, such as for example with methanol to produce methyl chloride, which is in turn used for the synthesis of methylchlorosilanes. In this way, chlorine can be recycled without having to be released into the environment.
The first step is preferably carried out without introducing mechanical energy (i.e. only natural convection). The circulation reactor, also referred to as loop reactor, is equipped with heating elements and preferably also with a phase separation unit with which any HCl-saturated alcohol phase formed can be returned to the circuit.
The second step is as follows: hydrolysis 1+ phase separation I
Within the scope of the invention, the details regarding the density are intended to be based on a temperature of 20 ℃ and the pressure of the surrounding atmosphere, i.e. 900 to 1100 hPa.
In the second step, the product of the first step is diluted with a water-insoluble organic solvent and preferably hydrolyzed with water in an amount of 1.5 to 5mol of water per mol of Si component.
In the context of the present invention, water-insoluble organic solvents are intended to mean those solvents which have a solubility of less than 1g of solvent per 100g of water at 25 ℃ and at the pressure of the surrounding atmosphere (i.e.900 to 1100 hPa).
Examples of the water-insoluble organic solvent used in the process of the present invention are preferably saturated straight-chain hydrocarbons such as n-pentane, n-hexane, n-heptane or n-octane, and branched-chain isomers thereof, and aromatic hydrocarbons such as benzene, toluene and xylene, and mixtures thereof. Toluene is preferably used.
The preferably water-insoluble organic solvent used in the second step of the process of the invention is metered in an amount of preferably from 0.5 to 50mol, more preferably from 1 to 30mol, in each case based on 1 mol of silicon component. The second step is preferably carried out in a batch reactor and with the introduction of mechanical energy (stirring, circulating pumping). The second step of the process of the invention is preferably carried out at a temperature of from 0 to 100 deg.c, more particularly from 20 to 80 deg.c, and at a pressure of preferably 500hPa and to 2000hPa, more preferably from 600 to 1500 hPa.
It has appeared that an improvement in the phase separation can be achieved if, in addition, 0.1 to 0.5mol of alcohol (for example EtOH), in each case based on 1 mol of silicon component, is preferably metered in. The alcohol can be added with water or with a mixture of organic solvents, or can be added only after the end of the metering in of water.
The third step: hydrolysis 2
In the third step, water is preferably added in an amount of 5 to 200mol of water per mol of the Si component.
Optionally also in the third step, a water-insoluble organic solvent may be added. This may be useful to achieve improved phase separation. Preferably, the water-insoluble organic solvents suitable for the third step of the process of the invention correspond in type and amount to those already disclosed under step two.
The third step is preferably carried out in a batch reactor and with the introduction of mechanical energy (stirring, circulating pumping), preferably in the same reactor as step two. The third step of the process of the invention is preferably carried out at a temperature of from 0 to 100 deg.c, more particularly from 20 to 80 deg.c, and at a pressure of preferably from 500hPa to 2000hPa, more preferably from 600 to 1500 hPa.
In addition to the aqueous dilution carried out, the hydrolysis and/or condensation reaction carried out in the third step can also be terminated by any desired method known so far, such as, preferably, for example, neutralization with a base (such as sodium hydroxide solution).
The fourth step: phase separation II
In the fourth step of the process of the present invention, the solvent-containing siloxane phase is separated from the aqueous phase. This can be done by methods known to the person skilled in the art, such as preferably leaving the reaction mixture to stand for 5 to 60 minutes until the phases have separated. The separated aqueous phase is passed for wastewater treatment.
Subsequently, in a fifth step (purification + concentration), the final product, i.e. a silicone resin solution of any concentration or a pure (undiluted) silicone resin, is produced from the siloxane-containing organic phase.
This treatment of the resulting organosiloxane phase is preferably carried out according to any desired method known in the art, for example neutralization, filtration and removal of all volatile components, preferably by distillation. The volatile components preferably comprise low-boiling siloxanes having a density of preferably less than 0.95kg/l and water-insoluble organic solvents. Furthermore, for example, in the case of the siloxane phase, the concentration can be increased by removing the solvent, for example by distillation in a thin-film evaporator, and in this way an organopolysiloxane resin solution can be produced, or the solvent can be removed completely to give a solvent-free organopolysiloxane resin.
According to the process of the present invention, a large number of organopolysiloxane resins or solutions having defined properties, such as, for example, those containing SiC bonding groups, hydroxyl groups and/or alkoxy groups, can be prepared reproducibly.
The organopolysiloxane resins prepared according to the invention can be solid or liquid at 20 ℃ and at pressures of 900 to 1100hPa, and they have an average molecular weight, measured with respect to polystyrene standards, of preferably at most 100000 g/mol, more preferably 800 to 10000 g/mol.
The organopolysiloxane resins prepared according to the present invention are preferably at least partially, but more preferably completely, soluble in alkoxysilanes and condensation products thereof, and also in liquid siloxanes.
The organopolysiloxane resins prepared according to the invention are preferably resins of the formula
[RSiO3/2]g[R2SiO]b[R3SiO1/2]c[SiO4/2]d[R1O1/2]e[HO1/2]f
Wherein R is methyl, isooctyl or phenyl, R1Is methyl, ethyl or butyl, g ═ 2-200, b ═ 0-100, c ═ 0-50, d ═ 0-10, e ═ 0-20 and f ═ 0-10.
Examples of organopolysiloxane resins prepared according to the invention are
[MeSiO3/2]72[Me2SiO]24[EtO1/2]2.8[HO1/2]0.4、
[MeSiO3/2]12.2[Me2SiO]3.3[Me3SiO1/2]1.4[EtO1/2]0.6[HO1/2]0.18、
[MeSiO3/2]15.3[Me2SiO]2.6[Me3SiO1/2]1[IOSiO3/2]0.8[MeO1/2]2[HO1/2]0.3And
[PhSiO3/2]9.8[Me2SiO]2[MeO1/2]1.8[BuO1/2]0.04[HO1/2]0.18where Me is methyl, Et is ethyl, IO is isooctyl, Ph is phenyl, and Bu is butyl.
The organopolysiloxane resins prepared according to the invention can be used for all purposes for which organopolysiloxane resins have hitherto also been used, for example for building maintenance, coatings, cosmetics, textiles and paper. In particular, they are suitable for the production of emulsions and as binders for the production of paints and varnishes, and as binders for the production of electrical insulation materials based on mica.
The method of the invention has the great advantage that the method is obviously more economical in the following aspects: the alcoholic HCl phase separated in the second step is reused in step 1 without further treatment and therefore makes the alcohol it contains available again for operation without having to be subjected beforehand to costly and inconvenient recoveries. The HCl introduced in step 1 leaves step 1 on this path in the form of HCl gas and can therefore likewise be reused.
A further advantage is that the aqueous phase separated in the fourth step contains hardly any more HCl or alcohol and can therefore be transported for waste water treatment without substantial loss of raw materials. Also, in this way, the need for high energy recovery of alcohol from acidic water is eliminated.
By means of the process of the present invention, organopolysiloxane resins are obtained which exhibit high storage stability, are very low in chlorides, have a low VOC content and can be produced very cost-effectively.
Furthermore, the process has the advantage that organopolysiloxane resins which are solid at ambient temperature can be prepared.
Examples
The following examples are intended to illustrate the invention without limiting it.
In the examples described below, all parts and percentages are by weight unless otherwise indicated. Unless otherwise indicated, the following examples were conducted at ambient atmospheric pressure, i.e., at about 1000hPa, and at room temperature, i.e., at about 25 deg.C, and/or the temperatures that occur when the reactants are brought together at room temperature without additional heating or cooling.
Comparative example 1
Step 1: partial alkoxylation analogous to EP2491071B1
A methylchlorosilane mixture consisting of 91% by weight of methyltrichlorosilane and 9% by weight of dimethyldichlorosilane was reacted continuously with a mixture of 81% by weight of EtOH and 18% by weight of water and 1% by weight of toluene (impurity in EtOH), as described in EP2491071B 1. (0.434 mol EtOH per mol SiCl and 0.243mol H per mol SiCl2O；H2Molar ratio of O/EtOH 0.56)
The ratio of the EtOH-water mixture to the methylchlorosilanes mixture was 0.48. The reaction temperature is from 31 to 32 ℃ and the gauge pressure is 300-310 mbar, and the mean residence time of the siloxane phase is from 20 to 24 minutes. The reaction product in the form of the resulting liquid partial alkoxylate contained 18.5 wt% Cl in the form of dissolved hydrogen chloride and Si-bonded Cl. The EtOH content in the form of free EtOH and in the form of Si-bonded EtO groups was 41 wt%.
74.5% by weight of the chlorine present in the chlorosilane mixture leaves process step 1 in the form of hydrogen chloride gas.
The recovered partial alkoxylate had a mass of 1.075g/cm3Density (25 ℃).
Step 2: hydrolysis 1
A mixture of 245g of the partial alkoxylate from step 1 and 350g of toluene (3.8mol) is initially introduced and 61.4g of water (3.4mol) are metered in with stirring over the course of 35 minutes. During this procedure, the temperature of the mixture rose from 25 ℃ to 54 ℃.
After the addition of water was complete, stirring was continued for another 30 minutes. Thereafter, 294.1g of water (16.3mol) were metered rapidly into the mixture over the course of 5 minutes with vigorous stirring.
And step 3: phase separation
After a waiting time of one hour, acidic water (468.5g) having an HCl content of the lower aqueous phase of 9.4 wt.% (44 g HCl absolute) was separated. (composition determined by GC: 68.9 wt% water; 20.94 wt% EtOH, 0.05 wt% toluene) (HCl content determined by titration is taken into account when evaluating GC).
The acidic water is distilled to recover ethanol. EtOH was obtained as overhead product. The HCl present goes with the bottom product into the waste water and is thus lost.
And 4, step 4: purification + concentration
The remaining 472.4g of toluene resin solution having a toluene content of 60.1% by weight was mixed with activated carbon, dicalite and NaHCO3The mixture of (a) was mixed and stirred and the solid was filtered off again.
The resin solution purified in this way was subsequently purged of low-boiling components at 175 ℃ under a final vacuum of as low as 10 mbar.
This gave 115.2g of tackifying resin (see Table 1 for analytical data) and 318.4g of distillate with a toluene content of more than 90% by weight.
Inventive example 1
Step 1: partial alkoxylation takes place analogously to comparative example 1
Step 2: hydrolysis 1+ phase separation I
A mixture of 246g of the partial alkoxylate from step 1 and 350g of toluene (3.8mol) was initially introduced and a mixture of 73.6g of water (4mol) and 14.7g (0.32mol) of EtOH (16.6% by weight EtOH in water) was metered in with stirring over the course of 34 minutes. The temperature of the mixture rose from 25 ℃ to 55 ℃.
After the end of the metering, stirring was continued for 30 minutes and, after a waiting time of 1h, the lower ethanolic HCl phase was separated off. This gave 213.5g of ethanol phase having a titration HCl content of 20.2% by weight (43.13g of HCl). (composition based on NMR: about 20 wt% HCl, <4 wt% EtOH and about 26 wt% water; <4 wt% toluene)
This mixture can be used again in step 1 for partial alkoxylation.
And step 3: hydrolysis 2
281.7g of water (15.6mol) are metered into the tolylsiloxane phase according to step 2 over the course of 5 minutes with vigorous stirring.
And 4, step 4: phase separation II
After a waiting time of one hour, a lower aqueous phase (279.1g) having an HCl content of 0.21% by weight (absolute content about 0.6g HCl) was separated off. (composition determined by GC: 98.1 wt% water; 1.82 wt% EtOH, 0.02 wt% toluene)
The aqueous phase contains only small amounts of HCl, ethanol, toluene and Sx and can be transported as process wastewater to wastewater treatment plants.
And 5: purification + concentration
The remaining 464.5g of toluene Sx phase having a toluene content of 65.5 wt% (34.5% Sx compound) was reacted with activated carbon, dicalite and NaHCO3The mixture of (a) is mixed and stirred and thus the solid is filtered off again and disposed of.
The resin solution purified in this way was subsequently purged of low-boiling components (mainly toluene) at 175 ℃ under a final vacuum of as low as 10 mbar.
This gave 112.3g of viscous resin and 297g of distillate. The toluene content of the distillate exceeded 90 wt% and it was reused in step 2.
Table 1 below shows the analytical data for the product from example 1 of the invention compared to the product from comparative example 1.
TABLE 1
Inventive example 1
Comparative example 1
100% resin yield [ g]
112
115
Viscosity (80 ℃ C.) [ mPas ]]
14 000
28 650
Viscosity of a 50 wt.% solution in toluene [ mm%2/s]
12
18
Total chlorine content [ ppm]
<3
<3
HCl titration [ ppm]
2.6
0.2
Mw[g/mol]
7500
7700
Mn[g/mol]
1650
1800
Polydispersity (Mw/Mn)
4
4
[Me2SiO2/2]wt[％](29Si-NMR)
11
11
[MeSiO3/2]wt[％](29Si-NMR)
83
84
Si-O1/2Et wt[％](29Si-NMR)
4.9
4.4
Si-OH wt[％](29Si-NMR)
0.71
0.73