METHOD FOR PRODUCING ALKYL SILICONES RESINS

Abstract

A process for producing alkyl silicone resins (A) containing at least 80 wt % of units of the general formula (I), R.sup.1.sub.a(R.sup.2O).sub.b(HO).sub.dR.sup.3.sub.cSiO.sub.(4-a-b-c-d)/2 (I), is provided. Alkylalkoxysilane (A1) of the general formula (II), R.sup.1.sub.aR.sup.3.sub.cSi(OR.sup.2).sub.(4-a-c) (II), is mixed in a first reaction step (R1), alternatively, with a pure acid (S) having pK.sub.a of not more than 5, with an at least 5 wt % aqueous solution of an acid (S) having a pK.sub.a of not more than 5 or with a halosilane compound (A2) of the general formula (III), R.sup.1.sub.aR.sup.3.sub.cSi(X).sub.(4-a-c) (III). Subsequently, in at least one further reaction step, (R2) water is added.

Claims

1-15. (canceled)

16. A process for producing alkyl silicone resins (A) containing at least 80 wt % of units of the general formula (I)
R.sup.1.sub.a(R.sup.2O).sub.b(HO).sub.dR.sup.3.sub.cSiO.sub.(4-a-b-c-d)/2  (I), where R.sup.1 may be identical or different and is a monovalent, SiC-bonded, unsubstituted or substituted aliphatic hydrocarbon radical having not more than 4 carbon atoms, R.sup.2 may be identical or different and is hydrogen or a monovalent, unsubstituted or substituted hydrocarbon radical having not more than 4 carbon atoms, R.sup.3 may be identical or different and is a monovalent, SiC-bonded, unsubstituted or substituted hydrocarbon radical having at least 5 carbon atoms, a is 0, 1, 2 or 3, b is 0, 1, 2 or 3 and c is 0, 1 or 2, with the proviso that the sum of a+b+c is less than or equal to 3 and in at least 50% of the units of the general formula (I) the sum of a+b is 0 or 1 and in at least 40% of the units of the general formula (I) c is 1, d is 0 or 1, and where the amount of alkoxy groups R.sup.2O is 3-20 wt %, where alkylalkoxysilane (A1) of the general formula (II)
R.sup.1.sub.aR.sup.3.sub.cSi(OR.sup.2).sub.(4-a-c)  (II), where R.sup.1, R.sup.2, R.sup.3, a and c have the definitions stated above, is mixed in a first reaction step (R1) alternatively with a pure acid (S) having pK.sub.a of not more than 5, with an at least 5 wt % aqueous solution of an acid (S) having a pK.sub.a of not more than 5 or with a halosilane compound (A2) of the general formula (III)
R.sup.1.sub.aR.sup.3.sub.cSi(X).sub.(4-a-c)  (III), where X is a halogen atom and R.sup.1, R.sup.3, a and c have the definitions stated above, and subsequently in at least one further reaction step (R2) water is added.

17. The process as claimed in claim 16, wherein R.sup.1 is selected from methyl and ethyl radical.

18. The process as claimed claim 16, wherein R.sup.2 is selected from methyl and ethyl radical.

19. The process as claimed in claim 16, wherein at least 90 mol % of all the radicals R.sup.3 are an alkyl group having 8 to 16 carbon atoms.

20. The process as claimed in claim 16, wherein the alkyl silicone resins (A) have at least 40 units of the general formula (I) in which a is 0 and c is 1, based in each case on the total number of units of the general formula (I).

21. The process as claimed in claim 16, wherein reaction steps (R1) and (R2) are followed by a further reaction step (R3) in which a base (B) is added in an amount greater than the amount of base (B) that would be needed in order to fully neutralize the amount of acid (S) present in the reaction mixture at the moment of addition of the base (B) or the amount of hydrogen halide liberated from the halosilane compound (A2) and present at that moment.

22. The process as claimed in claim 21, wherein the base (B) is selected from alkali metal or alkaline earth metal hydroxide or carbonate and alkali metal alkoxide.

23. The process as claimed in claim 16, wherein the alcohol R.sup.2OH liberated during the process is partially or completely removed distillatively in a further process step (R4).

24. The process as claimed in claim 21, wherein reaction step (R3) is carried out by adding the base (B) to the reaction mixture, on conclusion of reaction steps (R1) and (R2), in an amount greater than the amount that would be needed in order to fully neutralize the acid (S) used in reaction step (R1) or the hydrogen halide liberated from the halosilane compound (A2) used in reaction step 1.

25. The process as claimed in claim 24, wherein the salt obtained by the addition of base in process step (R3) and also, optionally, in one or more further neutralization steps (R5) as well is removed by a filtration step (R6).

26. The process as claimed in claim 21, wherein, in reaction step (R1), a halosilane compound (A2) or a hydrohalic acid is used, during or on conclusion of reaction step (R2) at least 30% of the amount of alcohol (R.sup.2OH) liberated in the preceding reaction steps is removed distillatively, with the hydrogen halide present in the reaction mixture being distilled off as well at least partially, and subsequently in process step (R3) the base (B) is added in an amount greater than the amount that would be needed in order to fully neutralize the amount of hydrohalic acid remaining in the reaction mixture.

27. The process as claimed in claim 26, wherein, during or on conclusion of reaction step (R2), at least 60% of the amount of alcohol (R.sup.2OH) liberated in the preceding reaction steps is removed distillatively.

28. The process as claimed in claim 26, wherein the alcohol R.sup.2OH still present in the reaction mixture after process step (R3) is partially or completely removed in a further distillation step (R4).

29. The process as claimed in claim 26, wherein, in reaction step (R1), an aqueous hydrochloric acid having an acid concentration of at least 5 wt % or the chlorosilane compound (A2), i.e., a compound of the formula (III), in which X is a chlorine atom, is used.

30. The process as claimed in claim 16, wherein the alkyl silicone resin (A) produced has an alcohol content of not more than 2 wt %.

Description

EXAMPLES

Inventive Example 1: Inventive Procedure of Particularly Preferred Embodiment (AF1)

[0112] Apparatus:

[0113] The reaction is carried out in a 1000 ml three-neck flask with heating facility (oil bath with magnetic stirrer), KPG stirrer, dropping funnel and reflux condenser.

[0114] Chemicals Used in Reaction Steps (R1) to (R3):

TABLE-US-00001 600.0 g of 1,4,4-trimethylpentyltriethoxysilane (2.17 mol) 2.5 g of 25 wt % aqueous hydrochloric acid (0.017 mol HCl, 0.104 mol H.sub.2O) 40.6 g of water (2.26 mol) 3.0 g of 50 wt % aqueous sodium hydroxide solution (0.038 mol NaOH, 0.083 mol H.sub.2O)

[0115] Procedure

[0116] 600.0 g of 1,4,4-trimethylpentyltriethoxysilane are introduced and heated to 65° C. At this temperature 2.5 g of 25% aqueous HCl are metered in with intense stirring at a uniform rate over the course of 20 min, with the reaction mixture initially undergoing slight clouding (2-phase system). Stirring is continued at 65° C. for 10 min, with the reaction mixture becoming clear again.

[0117] Thereafter, with the temperature unchanged, 40.6 g of water are metered in over the course of 30 min. A perceptibly exothermic reaction begins, and raises the reaction temperature to ˜70° C. To limit the temperature to 70° C., the reaction mixture is cooled after this temperature has been reached. The reaction mixture remains clear the entire time. After the end of metering, stirring is continued at 65° C. for 60 min.

[0118] Thereafter, with the temperature unchanged, a ph of ˜9-10 is established by addition of a 50% aqueous sodium hydroxide solution (3.0 g). Sodium chloride is precipitated as a white solid, but the reaction mixture remains a single phase. It is subsequently stirred for 30 min still at 65° C.

[0119] It is cooled to room temperature and neutralized by addition of 25% HCl (2.1 g) to pH 7. Stirring is continued for 30 min, during which the pH may rise again. In that case, the pH must be established again at 7 by addition of small amounts of acid.

[0120] After the reflux condenser has been replaced with a Claisen condenser with short column (around 1-2 plates), the low boilers are distilled off at an oil bath temperature of 120° C. and atmospheric pressure until further distillate is no longer produced. The liquid-phase temperature here rises continuously to 110° C. ˜225 g of distillate are obtained in this operation. Thereafter the pressure is reduced to 10 mbar, producing a further ˜5 g of distillate. After ˜15 min, no further distillate is produced even at this pressure, and the pressure is reduced to 5 mbar. Under these conditions, even very small residues of ethanol and/or water are removed from the reaction mixture for a further 30 min.

[0121] 406 g of residue in the form of a colorless liquid are obtained, containing the sodium chloride formed as a white solid.

[0122] Filtration:

[0123] g of Seitz EF filter aid are added to the material to be filtered (around 2.5 wt %) and distributed homogeneously by stirring.

[0124] Following the homogenization of the filter aid, the suspension at room temperature is placed into a pressure suction filter on K100 filter material, and the filter is closed and subjected to compressed air (around 5 bar).

[0125] After a short time, the filtrate begins to run off into the corresponding collection vessel. It is clear from the start. The compressed air feed is continued until there is no longer any run-off.

[0126] Thereafter the compressed air is switched off, the pressure suction filter is depressurized, and only then is the filter opened for cleaning.

[0127] Characterization of the End Product (Alkyl Silicone Resin (A)):

[0128] The end product is a clear liquid having a viscosity, measured by the method indicated in the description, of 185 mPas.

[0129] The end product is analyzed by means of .sup.1H and .sup.29Si-NMR distribution, with determinations of the amount of ethoxy groups, the distribution of the Si units over the various condensation stages, the amount of the silanol groups remaining in the product, and the amount of free ethanol remaining in the product. The result obtained in this case is as follows: [0130] Ethoxy content: 13.4 wt % (based on the total weight of the end product) [0131] Silanol content: 94 ppm (calculated as O.sub.1/2H (molar weight=9), based on the total weight of the end product) [0132] Ethanol content: 0.03 wt % (based on the total weight of the end product)

[0133] Distribution of the Si units over the various condensation stages: [0134] Si(OEt).sub.3 units: 0.8 mol % (monomeric silane) [0135] Si(OEt).sub.2O.sub.1/2 units: 16.2 mol % [0136] Si(OEt)O.sub.2/2 units: 55.6 mol % [0137] SiO.sub.3/2 units: 27.4 mol %

Inventive Example 2: Inventive Procedure of Particularly Preferred Embodiment (AF1)

[0138] The procedure is just the same as in inventive example 1, with the sole difference that instead of 600.0 g of 1,4,4-trimethylpentyltriethoxysilane, the same amount of n-octyl-triethoxysilane is used. The course of the reaction proved to be exactly the same.

[0139] Characterization of the End Product (Alkyl Silicone Resin (A)):

[0140] The end product is a clear liquid having a viscosity, measured by the method indicated in the description, of 223 mPas.

[0141] The end product is analyzed by means of .sup.1H and .sup.29Si-NMR distribution, with determinations of the amount of ethoxy groups, the distribution of the Si units over the various condensation stages, the amount of the silanol groups remaining in the product, and the amount of free ethanol remaining in the product. The result obtained in this case is as follows: [0142] Ethoxy content: 13.8 wt % (based on the total weight of the end product) [0143] Silanol content: 35 ppm (calculated as O.sub.1/2H (molar weight=9), based on the total weight of the end product) [0144] Ethanol content: 0.10 wt % (based on the total weight of the end product)

[0145] Distribution of the Si units over the various condensation stages: [0146] Si(OEt).sub.3 units: 1.0 mol % (monomeric silane) [0147] Si(OEt).sub.2O.sub.1/2 units: 18.3 mol % [0148] Si(OEt)O.sub.2/2 units: 50.3 mol % [0149] SiO.sub.3/2 units: 30.4 mol %

Inventive Example 3: Inventive Procedure of Particularly Preferred Embodiment (AF1)

[0150] The procedure is just as in inventive example 1, with the following differences: [0151] instead of 2.5 g of a 25 wt % aqueous hydrochloric acid, reaction step (R1) uses 2.0 g (0.008 mol) of 1,4,4-trimethylpentyltrichlorosilane as catalyst. In a reaction with water, this silane liberates 0.024 mmol of hydrogen chloride. [0152] instead of 3.0 g of a 50 wt % aqueous sodium hydroxide solution, reaction step (R3) uses 4.7 g of a sodium methoxide solution in methanol (0.026 mol NaOCH.sub.3). [0153] A neutralizing step (R5) is omitted, since following the addition of sodium methoxide in reaction step (R3) the reaction mixture already has a pH of 7.

[0154] The reaction regime otherwise and also the course of the reaction were exactly identical as described for inventive example 1.

[0155] Characterization of the End Product (Alkyl Silicone Resin (A)):

[0156] The end product is a clear liquid having a viscosity, measured by the method indicated in the description, of 175 mPas.

[0157] The end product is analyzed by means of .sup.1H and .sup.29Si-NMR distribution, with determinations of the amount of ethoxy groups, the distribution of the Si units over the various condensation stages, the amount of the silanol groups remaining in the product, and the amount of free ethanol remaining in the product. The result obtained in this case is as follows: [0158] Ethoxy content: 13.1 wt % (based on the total weight of the end product) [0159] Methoxy content: 0.3 wt % (based on the total weight of the end product) [0160] Silanol content: 174 ppm (calculated as O.sub.1/2H (molar weight=9), based on the total weight of the end product) [0161] Ethanol content: 0.05 wt % (based on the total weight of the end product)

[0162] Distribution of the Si units over the various condensation stages: [0163] Si(OR).sub.3 units: 0.9 mol % (monomeric silane) [0164] Si(OR).sub.2O.sub.1/2 units: 18.1 mol % [0165] Si(OR)O.sub.2/2 units: 55.8 mol % [0166] SiO.sub.3/2 units: 25.2 mol % [0167] where R=ethyl or methyl radical.

Comparative Example 1: Non-Inventive Procedure Reaction (Joint Addition of Acid (S) and Water)

[0168] The same apparatus, the same formulation and the same chemicals in the same amounts as in inventive example 1 are used. However, before the start of the reaction, the hydrochloric acid and the water are mixed together and metered jointly into the trimethylpentyltriethoxysilane over the course of 30 min at a reaction temperature of 65° C. with intense stirring. The reaction mixture becomes cloudy directly after the start of the addition. No heating of the reaction mixture is apparent. It is stirred at 65° C. for 6 h, with the reaction mixture acquiring a slight brownish discoloration.

[0169] Thereafter the reaction is terminated and the reaction mixture is cooled to room temperature and left to stand overnight.

[0170] After this, around 50 ml of a clear upper phase have separated, whereas the lower phase, which continues to have brownish discoloration, is still cloudy. An analysis of the two phases by 1H analysis shows that the upper phase consists essentially of ethanol and monomeric silane, whereas the lower phase consists of monomeric silane and the oligomeric target product in a molar ratio of around 1:1 and also of small amounts of ethanol. The reaction is therefore a long way off from a complete conversion. The reaction mixture was thereupon discarded.

Comparative Example 2: Non-Inventive Procedure Reaction (Addition of Acid (S) and Water in Reverse Order)

[0171] The same apparatus, the same formulation and the same chemicals in the same amounts as in inventive example 1 are used. Here, however, first the water and the trimethylpentyltriethoxysilane are mixed with intense stirring, with the resulting mixture turning cloudy. It is then heated to 65° C. and at this temperature over the course of 20 min the 25% hydrochloric acid is metered in with intense stirring. No heating of the reaction mixture is apparent. It is stirred at 65° C. for 6 h, with the reaction mixture acquiring a slight brownish discoloration.

[0172] Thereafter the reaction is terminated and the reaction mixture is cooled to room temperature and left to stand overnight.

[0173] On the next day, the result evident is essentially the same as for comparative example 1.

Comparative Example 3: Non-Inventive Procedure Reaction (Use of a Basic Rather than an Acidic Catalyst)

[0174] The apparatus used is the same as in inventive example 1.

[0175] Chemicals Used in Reaction Steps (R1) and (R2):

TABLE-US-00002 600.0 g of 1,4,4-trimethylpentyltriethoxysilane (2.17 mol) 3.1 g of 30 wt % sodium methoxide solution in methanol (0.017 mol NaOCH.sub.3) 42.5 g of water (2.36 mol)

[0176] Procedure

[0177] 600.0 g of 1,4,4-trimethylpentyltriethoxysilane are introduced and heated to 65° C. At this temperature, 3.1 g of 30 wt % sodium methoxide solution in methanol are metered in with intense stirring over the course of 20 min at a uniform rate. The reaction mixture here remains clear, but after just 5 min from the beginning of the addition it begins to take on a brown coloration. Stirring is continued for 10 min at 65° C. after the end of the addition, with the brown coloration becoming more intense.

[0178] Thereafter, with the temperature unchanged, 42.5 g of water are metered in over the course of 30 min. Directly after the start of the metering there is a distinct clouding of the reaction mixture. A very slight exothermic reaction begins, which raises the reaction temperature by 2-4° C. to 67-69° C. There is no need for cooling of the reaction mixture. After the end of metering, the earlier dark-brown and still cloudy reaction mixture is stirred for a further 5 h at 65° C.

[0179] Thereafter the reaction is terminated and the reaction mixture is cooled to room temperature and left to stand overnight.

[0180] After this, around 200 ml of an upper phase with slight brownish discoloration have separated, whereas the lower phase, with intense brown discoloration, is still cloudy. An analysis of the two phases by .sup.1H analysis shows that the upper phase consists essentially of ethanol and monomeric silane, whereas the lower phase consists of monomeric silane and the oligomeric target product in a molar ratio of around 1:2 and also of small amounts of ethanol. The reaction mixture was thereupon discarded.

Comparative Example 4: Non-Inventive Procedure Reaction (Use of a Basic Rather than an Acidic Catalyst)

[0181] The procedure is as in comparative example 3, with the use, instead of 3.1 g of wt % sodium methoxide solution (0.017 mol NaOCH.sub.3) in methanol, of 9.0 g (0.059 mol) of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) as basic catalyst.

[0182] Here as well, the reaction mixture remains clear during the addition of catalyst. There is no discoloration. With the commencement of addition of water, however, there is an immediate clouding of the reaction mixture in this case as well. There is, though, no discoloration. No exothermic heating of the reaction mixture can be observed.

[0183] After the termination of the reaction, after the end of the 5-hour subsequent stirring time, the reaction mixture is still cloudy. Overnight only a very small amount of an upper phase separates off. A .sup.1H analysis of the still cloudy lower reaction phase shows that significantly more than half of the alkoxysilane used is still present unchanged. The batch was thereupon discarded.

Inventive Example 4: Inventive Procedure of Particularly Preferred Embodiment (AF2)

[0184] The apparatus used is the same as in inventive example 1.

[0185] Chemicals Used in Reaction Steps (R1) and (R2):

TABLE-US-00003 600.0 g of 1,4,4-trimethylpentyltriethoxysilane (2.17 mol) 2.5 g of 25 wt % aqueous hydrochloric acid (0.017 mol HCl, 0.104 mol H.sub.2O) 46.0 g of water (2.56 mol)

[0186] Procedure

[0187] 600.0 g of 1,4,4-trimethylpentyltriethoxysilane are introduced and heated to 65° C. At this temperature 1.3 g of 25% aqueous HCl are metered in with intense stirring over the course of 20 min at a uniform rate, with the reaction mixture initially becoming slightly cloudy (2-phase system). Stirring is continued for 10 min at 65° C., with the reaction mixture becoming clear again.

[0188] Thereafter, with the temperature unchanged, 42.0 g of water are metered in over the course of 30 min. A perceptibly exothermic reaction begins, and raises the reaction temperature to ˜70° C. In order to limit the temperature to 70° C., the reaction mixture is cooled after this temperature has been attained. The reaction mixture remains clear for the whole time. After the end of metering, stirring is continued for 60 min at 65° C.

[0189] Following replacement of the reflux condenser with a Claisen condenser with short column (around 1-2 plates), the low boilers are distilled off at an oil bath temperature of 120° C. and atmospheric pressure until no further distillate is produced. The liquid-phase temperature here rises continuously to 110° C. In this case ˜220 g of distillate are obtained. Thereafter the pressure is reduced to 10 mbar, with a further ˜4 g of distillate being obtained. The reaction mixture obtained contains a chloride content of 43 ppm.

[0190] Thereafter the mixture is cooled to 65° C., and at this temperature 0.25 g of 50% aqueous sodium hydroxide solution (0.003 mol) is added, with the reaction mixture, which up to this point has been glass-clear, becoming slightly opaque. Directly after the addition of base, the reaction mixture has a pH of 4, which rises to ˜6 after stirring of 5 minutes and to 7 after stirring for 10 minutes. The reaction mixture is stirred in total after the addition of base for a further 45 min at 65° C.

[0191] Thereafter the low boilers are removed at an oil bath temperature of 120° C. and a pressure of 5 mbar, producing ˜5 g of distillate. After ˜30 min no further distillate is obtained, and the distillation is ended.

[0192] 403 g of residue in the form of a colorless liquid are obtained. The product exhibits a very slight clouding, but even after 14-day storage no perceptible amount of solid settles out.

[0193] Characterization of the End Product (Alkyl Silicone Resin (A)):

[0194] The end product is a clear liquid having a viscosity, measured by the method indicated in the description, of 238 mPas.

[0195] The end product is analyzed by means of .sup.1H and .sup.29Si-NMR distribution, with determinations of the amount of ethoxy groups, the distribution of the Si units over the various condensation stages, the amount of the silanol groups remaining in the product, and the amount of free ethanol remaining in the product. The result obtained in this case is as follows:

[0196] Ethoxy content: 13.1 wt % (based on the total weight of the end product) Silanol content: [0197] Silanol content: 338 ppm (calculated as O.sub.1/2H (molar weight=9), based on the total weight of the end product) [0198] Ethanol content: 0.11 wt % (based on the total weight of the end product)

[0199] Distribution of the Si units over the various condensation stages: [0200] Si(OEt).sub.3 units: 0.7 mol % (monomeric silane) [0201] Si(OEt).sub.2O.sub.1/2 units: 15.1 mol % [0202] Si(OEt)O.sub.2/2 units: 54.4 mol % [0203] SiO.sub.3/2 units: 29.8 mol %

Inventive Example 5: Inventive Though not Preferred Procedure of the Process of the Invention

[0204] The procedure is just the same as in inventive example 1, with the only differences that the addition of sodium hydroxide (reaction step (R3)) and also the neutralization of the end product (reaction step (R5)) are omitted. The procedure and course of all remaining reaction steps are exactly as described in inventive example 1.

[0205] Characterization of the End Product (Alkyl Silicone Resin (A)):

[0206] The end product is a clear liquid having a viscosity, measured by the method indicated in the description, of 125 mPas.

[0207] The end product is analyzed by means of .sup.1H and .sup.29Si-NMR distribution, with determinations of the amount of ethoxy groups, the amount of the silanol groups remaining in the product, and the amount of free ethanol remaining in the product. The result obtained in this case is as follows: [0208] Ethoxy content: 14.3 wt % (based on the total weight of the end product) [0209] Silanol content: 11.800 ppm (calculated as O.sub.1/2H (molar weight=9), based on the total weight of the end product [0210] Ethanol content: 0.21 wt % (based on the total weight of the end product)