CA2044696C - Process for the production of organosilicon compounds - Google Patents
Process for the production of organosilicon compoundsInfo
- Publication number
- CA2044696C CA2044696C CA 2044696 CA2044696A CA2044696C CA 2044696 C CA2044696 C CA 2044696C CA 2044696 CA2044696 CA 2044696 CA 2044696 A CA2044696 A CA 2044696A CA 2044696 C CA2044696 C CA 2044696C
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- Canada
- Prior art keywords
- carbon atoms
- organosilicon compound
- rubidium
- hydrocarbon groups
- production
- Prior art date
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Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/04—Polysiloxanes
- C08G77/06—Preparatory processes
- C08G77/08—Preparatory processes characterised by the catalysts used
Abstract
Process for the production of organosiloxanes comprising contacting (A) at least one organosilicon compound having in the molecule at least one silanol group, the organic substituents being selected from monovalent hydrocarbon groups having from 1 to 14 carbon atoms and monovalent substituted hydrocarbon groups having from 1 to 10 carbon atoms, with (B) one or more compounds selected from rubidium carbonate, cesium carbonate and carboxylates of rubidium and cesium.
Description
PROCESS FOR THE PRODUCTION OF
ORGANOSILICON COMPOUNDS
This invention relates to the production of organo-siloxanes and relates in particular to a process for the condensation of organosilicon compounds having silicon-bonded hydroxyl groups.
The production of organosiloxane polymers by the polymerisation or copolymerisation of relatively low mole-cular weight organosiloxanes is a well known step in the manufacture of commercial silicones. Generally the poly-merisation or copolymerisation is carried out by contacting cyclic organosiloxanes or low molecular weight siloxanols, or mixtures thereof, with an acidic or a basic catalyst.
Many substances which may be employed as catalysts have been described in the literature and include sulphuric acid, hydrochloric acid, Lewis acids, sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetra-butylphosphonium silanolate, amines and others. However, although such catalysts are effective in producing the desired increase in molecular weight of the starting materials, they have the disadvantage of causing scission and rearrangement of the siloxane bonds. As a result of such rearrangement the product often contains a significant proportion of low molecular weight siloxanes. For many applications, for example in the fabrication of silicone elastomers, it is necessary to remove such low molecular weight materials by devolatilisation in order to obtain a satisfactory product. Rearrangement of the siloxane bonds is also undesirable when the polymer is to contain a planned distribution of two or more types of organic subs-tituents, for example in the production of a polydimethyl-siloxane containing a proportion of organofunctional, e.g.
aminoalkyl, substituents.
Catalysts for promoting =SioH + =SioH and -SioH + SioR, R = organic, without siloxane bond cleavage have been disclosed in G.B. 895 091 and 918 823 and include for example tetramethylguanidine 2-ethylcaproate and n-hexylamine 2-ethylcaproate. However, many of such catalysts are liquids, or are not suitable for use at high temperatures, or are not readily removable from the product. There has, therefore, been a continuing search for substances which would be effective as catalysts for the production of condensation products of organosiloxanols but which would not cause molecular rearrangement and the consequent presence of significant amounts of low molecular weight species in the product. In particular the desired catalysts should preferably be suitable for use in hetero-geneous systems and remain active during use, thereby enabling their recovery and re-use in batch processes or their application in a continuous process.
We have now found that carbonates and certain carboxylates of rubidium and caesium have the ability to catalyse the condensation of organosilicon compounds. We have further found that said rubidium and caesium compounds can advantageously be employed in the production of organo-silicon polymers having a relatively low content of low molecular weight species.
Accordingly, the present invention provides a process for the production of organosiloxanes which comprises contacting (A) at least one organosilicon compound having in the molecule at least one silanol group and wherein the silicon-bonded organic substituents are selected from mono-valent hydrocabon groups having from 1 to 14 carbon atoms and monovalent substituted hydrocarbon groups having from 1 to 10 carbon atoms, the said substituted hydrocarbon groups being non-acidic in character, and (B) one or more 204~696 compounds selected from rubidium carbonate, caesium carbonate and carboxylates of rubidium and caesium of the general formula Q.CO.OM, wherein M represents Rb or Cs and Q represents an alkyl group having from 1 to 6 carbon atoms or an alkenyl group having from 2 to 5 carbon atoms.
The process of this invention may be applied in the production of condensation products of any type of organo-silicon compound having at least one silanol, that is -SioH, group in the molecule. Thus, the organosilicon compound may be an organosilane, organosiloxane or a silcarbane or mixtures of the same type or of different types of such organosilicon compounds. The silicon-bonded organic substituents in the organosilicon compound may be monovalent hydrocarbon groups having from 1 to 14 inclusive carbon atoms, for example alkyl, aryl, aralkyl, alkaryl or alkenyl groups, or they may be monovalent substituted hydrocarbon groups having up to 10 carbon atoms and which are non-acidic in character, that is groups not containing acidic substituents such as carboxyl, sulphate and sulphonic. Examples of operative non-acidic groups are amino-substituted alkyl and aryl groups, mercaptoalkyl groups, haloalkyl groups, cyanoalkyl groups and hydroxy alkyl groups. Specific examples of the organic substi tuents which may be present in the organosilicon compounds employed in the process of this invention are methyl, ethyl, propyl, hexyl, dodecyl, tetradecyl, phenyl, xylyl, tolyl, phenylethyl, vinyl, allyl, hexenyl, -RNH2, -RNHCH2CH2NH2, -RSH, -RBr, -RCl and -ROH wherein R repre-sents a divalent organic group, preferably having less than 8 carbon atoms for example alkylene e.g. -(CH2)3- and CH CHCH CH -, arylene e.g. C6H4 -(C6H3.CH3)-. For the majority of commercial applications at least 50% of the total organic substituents in (A) will ~ ~ 4 4 ~ ~ ~
be methyl groups,any remaining substituents being selected from phenyl and vinyl groups.
Although applicable to any type of organosilicon compound having at least one silanol group the process of this invention is particularly useful for the production of higher molecular weight organosiloxane polymers from lower molecular weight hydroxylated species. For example, during the production of organosiloxanes by the hydrolysis of the corresponding organochlorosilanes there is obtained a mixture of low molecular weight organosiloxanes having two or more silanol groups per molecule. The process of this invention may be employed to increase the molecular weight of such organosiloxanes where the production of high proportions of volatile siloxanes may be undesirable.
According to a preferred embodiment of this invention the organosilicon compounds (A) are silanol-terminated polydi-organosiloxanes, that is substantially linear organo-siloxane polymers or oligomers having a hydroxyl group attached to each terminal silicon atom. Such polydiorgano-siloxanes include those which can be represented by the average general formula R' R' HO - Si os i OH
R' R' n wherein each R' represents the hereinabove defined organic substituents and n is an integer, preferably from 1 to about 100. As hereinbefore stated, commercially the R' substituents are normally predominantly methyl,with any remaining R' substituents being selected from vinyl and phenyl.
If desired the condensation products may be end-stopped with triorganosiloxy units. One method of effecting such end-stopping comprises incorporating in the reaction mixture a triorganosilane, for example a triorganoalkoxysilane, which is reactive with the condensation product. Such a reaction may be effected in the presence of a suitable catalyst, for example - barium or strontium hydroxide as described in Canadian Patent Application No. 2,009,276 of S.B. Rees and S.
Westall, published August 9, 1990. However, a more preferred method of producing end-stopped polydiorganosiloxanes employing the process of this invention comprises employing as the organosilicon compound (A) both (i) at lease one polydiorganosiloxane - having a hydroxyl group attached to each terminal silicon atom, and (ii) a polydiorganosiloxane terminated with a hydroxyl group at one end and a triorganosiloxy group at the other.
The catalyst substance (B) is a carbonate or carboxylate of rubidium or caesium. In the general formula of the carboxylates Q may be for example methyl, ethyl, propyl, hexyl, vinyl or allyl. Specific examples of catalyst (B) are rubidium carbonate, caesium carbonate, rubidium acetate, caesium propionate, caesium butyrate and rubidium acrylate. The particle size of the catalyst substance is not critical. Generally, the smaller the particles the greater is the catalytic surface available.
However, very fine particle size powders may be more difficult to remove from the condensation product.
The process of this invention involves contacting the organosilicon compound (A) with the catalyst (B) at a temperature at which the desired rate of molecular weight increase occurs. The temperatures employed may vary within wide limits,for example from about 30~C to about 200~C.
Reaction at the lower temperatures is, however, normally too slow for commercial purposes and the process is prefer-ably carried out at temperatures within the range from about 700C to 150~C. It is also preferred to accelerate the removal of water formed during the condensation reac-tion by carrying out the process under reduced pressure, that is, at a pressure less than normal atmospheric and most preferably less than about 0.5 bar (0.5 x 105 Pa).
One method of carrying out the process is by means of a batch procedure. For example, the catalyst may be dispersed in the organosilicon compound and the mixture raised to the required temperature. Alternatively, the organosilicon compound may be preheated prior to the addition of the catalyst. Advantageously the mixture is agitated during the reaction period to maintain the catalyst in suspension. Sufficient catalyst is employed to achieve the desired rate of condensation having regard to the nature and geometry of the processing equipment, tempe-rature and other factors. From considerations of speed of reaction and economy of operation we prefer to employ from about 0.001 to about 5~ by weight of the catalyst based on the weight of the organosilicon compound. Termination of the condensation reaction, if desired, may be achieved for example by lowering the temperature of the mixture, and/or raising the reaction pressure to atmospheric and/or by separation or neutralisation of the catalyst.
Because of their heterogeneous nature the catalysts (B) are particularly adapted for use in processes involving manufacture on a continuous, rather than a batch, basis.
Properly employed such so-called 'continuous processes' avoid the delays and costs common to batch processing, for example those involved in the charging and discharging of the reaction vessel and separation of the catalyst material from the product. Thus, for example, the process of this invention may be advantageously employed for the continuous production of higher molecular weight siloxane polymers from lower molecular weight hydroxyl-containing species.
. ~
~ ~ ~ 4 ~ ~ ~
When carrying out the process of this invention in a continuous mode contact between the catalyst material and the organosilicon compound may be achieved by passing the organosilicon compound over or through a bed containing the catalyst material. When employing viscous reactants or products it may be necessary to adjust the porosity of the bed by granulation of the catalyst or other means. We have found that a particularly suitable form of bed for conti-nuous operation can be obtained by depositing the catalyst substance in or on a particulate solid material, for example silica, which is substantially inert under the process conditions and which has a particle size appro-priate to the desired porosity of the bed.
The condensation products produced by the process of this invention may be employed in any of the variety of applications known for the corresponding products made by prior art procedures. For example they may be used for treating textiles to render them water repellent and impart softness, as components of paper coating compositions, as heat transfer liquids and in the production of adhesives and sealing materials.
The following Examples illustrate the invention.
ExamPle 1 2g of rubidium carbonate Rb2CO3 was added to 100g of a linear ~,~ silanol terminated polydimethylsiloxane having an average molecular weight of 3,300 and silanol content of 1.1% by weight (as OH). The mixture was agitated and heated to 100~C at a pressure of 100mm.Hg (13.3 kPa).
After two hours the mixture was cooled and filtered. The filtrate was a siloxane polymer having an average molecular weight of 53,800 and silanol content 0.064% by weight (as OH). The non-volatile content of the product polymer (measured by weight loss in a forced draught oven at 150~C
.
~.
_ 9 _ for 3 hours on a lg sample) was 98.6% by weight. The starting polymer had a corresponding non-volatile content of 97.5% indicating that no additional volatile cyclo-siloxanes were formed during the polymerisation process.
ExamPle 2 The procedure of Example 1 was followed but substi-tuting caesium carbonate Cs2CO3.2H2O for the rubidium salt.
All other conditions were identical. The product polymer had an average molecular weight of 96,300, a silanol content of 0.03S% by weight (as OH) and a non-volatile content of 98.5% by weight.
ExamPle 3 The procedure of Example 1 was repeated except that rubidium acetate RbOCCH3 and cesium acetate CsOCCH3 O O
respectively were substituted for the rubidium carbonate.
The results were as follows:
Starting PolYmer Product Pol,ymer SioH% SiOH% Non-Volatile Mn w/w_ Mn w/w_ Content RbOAc 3,300 1.1 10,330 0.32 98.2 CsOAc 3,300 1.1 26,030 0.13 98.3 Example 4 250ml of "Harshaw"* A1-0104T neutral alumina, 3mm pellets were slurried overnight with a solution of 150g of Cs2CO3 in 100ml of distilled water. The saturated pellets were drained and oven-dried to constant weight. The pellets had a calculated Cs2CO3 content of 25.6% by weight.
A 100 x 2.5cm ID glass column was packed along its total length with the treated pellets and fixed vertically.
The column was wrapped with electrical heating tape and heated to a temperature of 130~C. A product receiving flask was fitted to the bottom of the column and the system * Trademark ~044696 was evacuated to 50mm Hg (6.67 kPa) pressure. A polydi-methylsiloxane of average molecular weight 3,300 was heated to 120 to 130~C and fed into the upper opening of the glass column at a rate sufficient to allow the feed to trickle over the packing without flooding. A countercurrent dry nitrogen flow of 0.5 cu ft/hour was also employed to aid in the removal of water formed by condensation. After one pass through the column the viscosity of the polydimethyl-siloxane had increased and the silanol content had fallen as follows:
SampleTotal OH H2O SioHViscosity ppm _ ~e_ EE__cS at 25~C
Feedstock15100 1181 13919 87.0 Product 6700 103 65971700.0 Gpc analysis of the polymer product showed no evidence of siloxane bond rearrangement, e.g. the presence of dimethyl cyclics.
Example 5 lg of caesium carbonate was added to 200g of a linear methylvinylpolysiloxane fluid with terminal silanol functionality _ _ HO - SiO - H
CH=CH2 n -6 2 having a viscosity at 25~C of 54.7 cS (54.7 x 10 m /s)-The mixture was heated to 100~C under a reduced pressure of 40mbar (4 x 103 Pa) with constant agitation. After 2 hours the mixture was cooled. The cooled product had a viscosity of 156,667 cS (157 x 10 3 m2/s) 25~C.
When the experiment was repeated using lg of caesium acetate in place of the carbonate and identical reaction conditions, the viscosity of the methylvinylsiloxane fluid increased from 54.7 cS at 25~C to 24,343 cS (24.3 x 10 m /s).
ORGANOSILICON COMPOUNDS
This invention relates to the production of organo-siloxanes and relates in particular to a process for the condensation of organosilicon compounds having silicon-bonded hydroxyl groups.
The production of organosiloxane polymers by the polymerisation or copolymerisation of relatively low mole-cular weight organosiloxanes is a well known step in the manufacture of commercial silicones. Generally the poly-merisation or copolymerisation is carried out by contacting cyclic organosiloxanes or low molecular weight siloxanols, or mixtures thereof, with an acidic or a basic catalyst.
Many substances which may be employed as catalysts have been described in the literature and include sulphuric acid, hydrochloric acid, Lewis acids, sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetra-butylphosphonium silanolate, amines and others. However, although such catalysts are effective in producing the desired increase in molecular weight of the starting materials, they have the disadvantage of causing scission and rearrangement of the siloxane bonds. As a result of such rearrangement the product often contains a significant proportion of low molecular weight siloxanes. For many applications, for example in the fabrication of silicone elastomers, it is necessary to remove such low molecular weight materials by devolatilisation in order to obtain a satisfactory product. Rearrangement of the siloxane bonds is also undesirable when the polymer is to contain a planned distribution of two or more types of organic subs-tituents, for example in the production of a polydimethyl-siloxane containing a proportion of organofunctional, e.g.
aminoalkyl, substituents.
Catalysts for promoting =SioH + =SioH and -SioH + SioR, R = organic, without siloxane bond cleavage have been disclosed in G.B. 895 091 and 918 823 and include for example tetramethylguanidine 2-ethylcaproate and n-hexylamine 2-ethylcaproate. However, many of such catalysts are liquids, or are not suitable for use at high temperatures, or are not readily removable from the product. There has, therefore, been a continuing search for substances which would be effective as catalysts for the production of condensation products of organosiloxanols but which would not cause molecular rearrangement and the consequent presence of significant amounts of low molecular weight species in the product. In particular the desired catalysts should preferably be suitable for use in hetero-geneous systems and remain active during use, thereby enabling their recovery and re-use in batch processes or their application in a continuous process.
We have now found that carbonates and certain carboxylates of rubidium and caesium have the ability to catalyse the condensation of organosilicon compounds. We have further found that said rubidium and caesium compounds can advantageously be employed in the production of organo-silicon polymers having a relatively low content of low molecular weight species.
Accordingly, the present invention provides a process for the production of organosiloxanes which comprises contacting (A) at least one organosilicon compound having in the molecule at least one silanol group and wherein the silicon-bonded organic substituents are selected from mono-valent hydrocabon groups having from 1 to 14 carbon atoms and monovalent substituted hydrocarbon groups having from 1 to 10 carbon atoms, the said substituted hydrocarbon groups being non-acidic in character, and (B) one or more 204~696 compounds selected from rubidium carbonate, caesium carbonate and carboxylates of rubidium and caesium of the general formula Q.CO.OM, wherein M represents Rb or Cs and Q represents an alkyl group having from 1 to 6 carbon atoms or an alkenyl group having from 2 to 5 carbon atoms.
The process of this invention may be applied in the production of condensation products of any type of organo-silicon compound having at least one silanol, that is -SioH, group in the molecule. Thus, the organosilicon compound may be an organosilane, organosiloxane or a silcarbane or mixtures of the same type or of different types of such organosilicon compounds. The silicon-bonded organic substituents in the organosilicon compound may be monovalent hydrocarbon groups having from 1 to 14 inclusive carbon atoms, for example alkyl, aryl, aralkyl, alkaryl or alkenyl groups, or they may be monovalent substituted hydrocarbon groups having up to 10 carbon atoms and which are non-acidic in character, that is groups not containing acidic substituents such as carboxyl, sulphate and sulphonic. Examples of operative non-acidic groups are amino-substituted alkyl and aryl groups, mercaptoalkyl groups, haloalkyl groups, cyanoalkyl groups and hydroxy alkyl groups. Specific examples of the organic substi tuents which may be present in the organosilicon compounds employed in the process of this invention are methyl, ethyl, propyl, hexyl, dodecyl, tetradecyl, phenyl, xylyl, tolyl, phenylethyl, vinyl, allyl, hexenyl, -RNH2, -RNHCH2CH2NH2, -RSH, -RBr, -RCl and -ROH wherein R repre-sents a divalent organic group, preferably having less than 8 carbon atoms for example alkylene e.g. -(CH2)3- and CH CHCH CH -, arylene e.g. C6H4 -(C6H3.CH3)-. For the majority of commercial applications at least 50% of the total organic substituents in (A) will ~ ~ 4 4 ~ ~ ~
be methyl groups,any remaining substituents being selected from phenyl and vinyl groups.
Although applicable to any type of organosilicon compound having at least one silanol group the process of this invention is particularly useful for the production of higher molecular weight organosiloxane polymers from lower molecular weight hydroxylated species. For example, during the production of organosiloxanes by the hydrolysis of the corresponding organochlorosilanes there is obtained a mixture of low molecular weight organosiloxanes having two or more silanol groups per molecule. The process of this invention may be employed to increase the molecular weight of such organosiloxanes where the production of high proportions of volatile siloxanes may be undesirable.
According to a preferred embodiment of this invention the organosilicon compounds (A) are silanol-terminated polydi-organosiloxanes, that is substantially linear organo-siloxane polymers or oligomers having a hydroxyl group attached to each terminal silicon atom. Such polydiorgano-siloxanes include those which can be represented by the average general formula R' R' HO - Si os i OH
R' R' n wherein each R' represents the hereinabove defined organic substituents and n is an integer, preferably from 1 to about 100. As hereinbefore stated, commercially the R' substituents are normally predominantly methyl,with any remaining R' substituents being selected from vinyl and phenyl.
If desired the condensation products may be end-stopped with triorganosiloxy units. One method of effecting such end-stopping comprises incorporating in the reaction mixture a triorganosilane, for example a triorganoalkoxysilane, which is reactive with the condensation product. Such a reaction may be effected in the presence of a suitable catalyst, for example - barium or strontium hydroxide as described in Canadian Patent Application No. 2,009,276 of S.B. Rees and S.
Westall, published August 9, 1990. However, a more preferred method of producing end-stopped polydiorganosiloxanes employing the process of this invention comprises employing as the organosilicon compound (A) both (i) at lease one polydiorganosiloxane - having a hydroxyl group attached to each terminal silicon atom, and (ii) a polydiorganosiloxane terminated with a hydroxyl group at one end and a triorganosiloxy group at the other.
The catalyst substance (B) is a carbonate or carboxylate of rubidium or caesium. In the general formula of the carboxylates Q may be for example methyl, ethyl, propyl, hexyl, vinyl or allyl. Specific examples of catalyst (B) are rubidium carbonate, caesium carbonate, rubidium acetate, caesium propionate, caesium butyrate and rubidium acrylate. The particle size of the catalyst substance is not critical. Generally, the smaller the particles the greater is the catalytic surface available.
However, very fine particle size powders may be more difficult to remove from the condensation product.
The process of this invention involves contacting the organosilicon compound (A) with the catalyst (B) at a temperature at which the desired rate of molecular weight increase occurs. The temperatures employed may vary within wide limits,for example from about 30~C to about 200~C.
Reaction at the lower temperatures is, however, normally too slow for commercial purposes and the process is prefer-ably carried out at temperatures within the range from about 700C to 150~C. It is also preferred to accelerate the removal of water formed during the condensation reac-tion by carrying out the process under reduced pressure, that is, at a pressure less than normal atmospheric and most preferably less than about 0.5 bar (0.5 x 105 Pa).
One method of carrying out the process is by means of a batch procedure. For example, the catalyst may be dispersed in the organosilicon compound and the mixture raised to the required temperature. Alternatively, the organosilicon compound may be preheated prior to the addition of the catalyst. Advantageously the mixture is agitated during the reaction period to maintain the catalyst in suspension. Sufficient catalyst is employed to achieve the desired rate of condensation having regard to the nature and geometry of the processing equipment, tempe-rature and other factors. From considerations of speed of reaction and economy of operation we prefer to employ from about 0.001 to about 5~ by weight of the catalyst based on the weight of the organosilicon compound. Termination of the condensation reaction, if desired, may be achieved for example by lowering the temperature of the mixture, and/or raising the reaction pressure to atmospheric and/or by separation or neutralisation of the catalyst.
Because of their heterogeneous nature the catalysts (B) are particularly adapted for use in processes involving manufacture on a continuous, rather than a batch, basis.
Properly employed such so-called 'continuous processes' avoid the delays and costs common to batch processing, for example those involved in the charging and discharging of the reaction vessel and separation of the catalyst material from the product. Thus, for example, the process of this invention may be advantageously employed for the continuous production of higher molecular weight siloxane polymers from lower molecular weight hydroxyl-containing species.
. ~
~ ~ ~ 4 ~ ~ ~
When carrying out the process of this invention in a continuous mode contact between the catalyst material and the organosilicon compound may be achieved by passing the organosilicon compound over or through a bed containing the catalyst material. When employing viscous reactants or products it may be necessary to adjust the porosity of the bed by granulation of the catalyst or other means. We have found that a particularly suitable form of bed for conti-nuous operation can be obtained by depositing the catalyst substance in or on a particulate solid material, for example silica, which is substantially inert under the process conditions and which has a particle size appro-priate to the desired porosity of the bed.
The condensation products produced by the process of this invention may be employed in any of the variety of applications known for the corresponding products made by prior art procedures. For example they may be used for treating textiles to render them water repellent and impart softness, as components of paper coating compositions, as heat transfer liquids and in the production of adhesives and sealing materials.
The following Examples illustrate the invention.
ExamPle 1 2g of rubidium carbonate Rb2CO3 was added to 100g of a linear ~,~ silanol terminated polydimethylsiloxane having an average molecular weight of 3,300 and silanol content of 1.1% by weight (as OH). The mixture was agitated and heated to 100~C at a pressure of 100mm.Hg (13.3 kPa).
After two hours the mixture was cooled and filtered. The filtrate was a siloxane polymer having an average molecular weight of 53,800 and silanol content 0.064% by weight (as OH). The non-volatile content of the product polymer (measured by weight loss in a forced draught oven at 150~C
.
~.
_ 9 _ for 3 hours on a lg sample) was 98.6% by weight. The starting polymer had a corresponding non-volatile content of 97.5% indicating that no additional volatile cyclo-siloxanes were formed during the polymerisation process.
ExamPle 2 The procedure of Example 1 was followed but substi-tuting caesium carbonate Cs2CO3.2H2O for the rubidium salt.
All other conditions were identical. The product polymer had an average molecular weight of 96,300, a silanol content of 0.03S% by weight (as OH) and a non-volatile content of 98.5% by weight.
ExamPle 3 The procedure of Example 1 was repeated except that rubidium acetate RbOCCH3 and cesium acetate CsOCCH3 O O
respectively were substituted for the rubidium carbonate.
The results were as follows:
Starting PolYmer Product Pol,ymer SioH% SiOH% Non-Volatile Mn w/w_ Mn w/w_ Content RbOAc 3,300 1.1 10,330 0.32 98.2 CsOAc 3,300 1.1 26,030 0.13 98.3 Example 4 250ml of "Harshaw"* A1-0104T neutral alumina, 3mm pellets were slurried overnight with a solution of 150g of Cs2CO3 in 100ml of distilled water. The saturated pellets were drained and oven-dried to constant weight. The pellets had a calculated Cs2CO3 content of 25.6% by weight.
A 100 x 2.5cm ID glass column was packed along its total length with the treated pellets and fixed vertically.
The column was wrapped with electrical heating tape and heated to a temperature of 130~C. A product receiving flask was fitted to the bottom of the column and the system * Trademark ~044696 was evacuated to 50mm Hg (6.67 kPa) pressure. A polydi-methylsiloxane of average molecular weight 3,300 was heated to 120 to 130~C and fed into the upper opening of the glass column at a rate sufficient to allow the feed to trickle over the packing without flooding. A countercurrent dry nitrogen flow of 0.5 cu ft/hour was also employed to aid in the removal of water formed by condensation. After one pass through the column the viscosity of the polydimethyl-siloxane had increased and the silanol content had fallen as follows:
SampleTotal OH H2O SioHViscosity ppm _ ~e_ EE__cS at 25~C
Feedstock15100 1181 13919 87.0 Product 6700 103 65971700.0 Gpc analysis of the polymer product showed no evidence of siloxane bond rearrangement, e.g. the presence of dimethyl cyclics.
Example 5 lg of caesium carbonate was added to 200g of a linear methylvinylpolysiloxane fluid with terminal silanol functionality _ _ HO - SiO - H
CH=CH2 n -6 2 having a viscosity at 25~C of 54.7 cS (54.7 x 10 m /s)-The mixture was heated to 100~C under a reduced pressure of 40mbar (4 x 103 Pa) with constant agitation. After 2 hours the mixture was cooled. The cooled product had a viscosity of 156,667 cS (157 x 10 3 m2/s) 25~C.
When the experiment was repeated using lg of caesium acetate in place of the carbonate and identical reaction conditions, the viscosity of the methylvinylsiloxane fluid increased from 54.7 cS at 25~C to 24,343 cS (24.3 x 10 m /s).
Claims (7)
1. A process for the production of organosiloxanes which comprises contacting (A) at least one organosilicon compound having in the molecule at least one silanol group and wherein the silicon-bonded organic substituents are selected from monovalent hydrocarbon groups having from 1 to 14 carbon atoms and monovalent substituted hydrocarbon groups having from 1 to 10 carbon atoms, the said substituted hydrocarbon groups being non-acidic in character, and (B) one or more compounds selected from rubidium carbonate, cesium carbonate and carboxylates of rubidium and cesium of the general formula Q.CO.OM, in which M
represents Rb or Cs and Q represents an alkyl group having from 1 to 6 carbon atoms or an alkenyl group having from 2 to 5 carbon atoms, said contacting being effected at a temperature ranging from about 30°C to about 200°C.
represents Rb or Cs and Q represents an alkyl group having from 1 to 6 carbon atoms or an alkenyl group having from 2 to 5 carbon atoms, said contacting being effected at a temperature ranging from about 30°C to about 200°C.
2. A process as claimed in Claim 1 wherein (A) and (B) are contacted at a temperature within the range from 70°C to 150°C.
3. A process as claimed in Claim 1 wherein (A) and (B) are contacted under a pressure of less than 0.5 x 10 5 Pa.
4. A process as claimed in Claim 1 wherein (B) is employed in a proportion of from 0.001 to 5% by weight based on the weight of the organosilicon compound (A).
5. A process as claimed in Claim 1 wherein (B) is present dispersed on or in a particulate solid which is substantially inert under the reaction conditions.
6. A process as claimed in Claim 1 wherein organosilicon compound (A) comprises both (i) at least one polydiorganosiloxane having a hydroxyl group attached to each terminal silicon atom, and (ii) a polydiorganosiloxane terminated with a hydroxyl group at one end and a triorganosiloxy group at the other.
7. A process as claimed in Claim 1 wherein (A) is passed through a bed containing (B).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9014450.2 | 1990-06-28 | ||
| GB909014450A GB9014450D0 (en) | 1990-06-28 | 1990-06-28 | Process for the production of organosilicon compounds |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2044696A1 CA2044696A1 (en) | 1991-12-29 |
| CA2044696C true CA2044696C (en) | 1998-08-18 |
Family
ID=10678385
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2044696 Expired - Fee Related CA2044696C (en) | 1990-06-28 | 1991-06-14 | Process for the production of organosilicon compounds |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPH04236230A (en) |
| CA (1) | CA2044696C (en) |
| DE (1) | DE4121308A1 (en) |
| FR (1) | FR2663941B1 (en) |
| GB (2) | GB9014450D0 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5512650A (en) * | 1986-06-20 | 1996-04-30 | Minnesota Mining And Manufacturing Company | Block copolymer, method of making the same, diamine precursors of the same, method of making such diamines and end products comprising the block copolymer |
| US5214119A (en) * | 1986-06-20 | 1993-05-25 | Minnesota Mining And Manufacturing Company | Block copolymer, method of making the same, dimaine precursors of the same, method of making such diamines and end products comprising the block copolymer |
| GB9105372D0 (en) * | 1991-03-14 | 1991-05-01 | Dow Corning Sa | Method of making siloxane compositions |
| DE4207212A1 (en) * | 1992-03-06 | 1993-09-09 | Bayer Ag | METHOD FOR PRODUCING ORGANYLOXY END-STOPPED POLYSILOXANS |
| GB9227152D0 (en) * | 1992-12-31 | 1993-02-24 | Dow Corning | Process for loading ceramic monolith with catalyst |
| US5867559A (en) * | 1996-02-20 | 1999-02-02 | Eis International, Inc. | Real-time, on-line, call verification system |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3433764A (en) * | 1965-10-11 | 1969-03-18 | Owens Illinois Inc | Art of producing siloxane condensation products |
| JPS5294352A (en) * | 1976-02-04 | 1977-08-08 | Toray Silicone Co Ltd | Moldable silicone resin composition |
| DE3003116A1 (en) * | 1980-01-29 | 1981-08-06 | Wacker-Chemie GmbH, 8000 München | METHOD FOR PRODUCING ORGANOSILOXANE BLOCK MIXED POLYMER |
| US4704443A (en) * | 1986-10-27 | 1987-11-03 | Dow Corning Corporation | Method of reducing activity of silicone polymers |
| GB8902937D0 (en) * | 1989-02-09 | 1989-03-30 | Dow Corning | Process for the production of organosilicon compounds |
-
1990
- 1990-06-28 GB GB909014450A patent/GB9014450D0/en active Pending
-
1991
- 1991-06-14 CA CA 2044696 patent/CA2044696C/en not_active Expired - Fee Related
- 1991-06-20 GB GB9113327A patent/GB2256872B/en not_active Expired - Fee Related
- 1991-06-21 FR FR9107653A patent/FR2663941B1/en not_active Expired - Fee Related
- 1991-06-26 JP JP15476891A patent/JPH04236230A/en active Pending
- 1991-06-27 DE DE19914121308 patent/DE4121308A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| CA2044696A1 (en) | 1991-12-29 |
| FR2663941A1 (en) | 1992-01-03 |
| GB9014450D0 (en) | 1990-08-22 |
| FR2663941B1 (en) | 1994-09-02 |
| DE4121308A1 (en) | 1992-01-02 |
| GB2256872B (en) | 1993-12-22 |
| JPH04236230A (en) | 1992-08-25 |
| GB2256872A (en) | 1992-12-23 |
| GB9113327D0 (en) | 1991-08-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |