Preparation of polysiloxanes by polycondensation using acid / base catalysts simultaneously

Abstract

The process for preparing polysiloxane is a two-step polycondensation of alkoxysilane and / or alkoxysiloxane, which includes (a) a step of hydrolyzing alkoxysilane and / or alkoxysiloxane to form hydroxyl-functional silane and / or hydroxyl-functional siloxane, and (b) a step of condensing the hydroxyl-functional silane and / or the hydroxyl-functional siloxane to form a polysiloxane polycondensation product. The process is characterized by having both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst that are present simultaneously throughout both the hydrolysis step and the condensation step.

Description

[Technical Field]

[0001] The present invention relates to a method for preparing polysiloxanes by a polycondensation reaction involving hydrolysis and condensation reactions in the simultaneous presence of a gel-type heterogeneous acid catalyst and a base catalyst.

[0002] Introduction One route to preparing polysiloxanes is via a two-step polycondensation reaction of alkoxysilanes and / or alkoxysiloxanes. The first step requires hydrolysis of the alkoxysilanes and / or alkoxysiloxanes to form hydroxy-functional silanes and / or siloxanes. The second step requires polycondensation of the hydroxy-functional silanes and / or siloxanes. Acid and base catalysts are useful for accelerating the reaction rates in the two steps of the polycondensation reaction. The reaction process typically requires the use of an acid catalyst for the hydrolysis step and a base catalyst for the polycondensation step.

[0003] The catalyst may be a "homogeneous" catalyst, meaning that the catalyst forms a uniform solution with the reaction solution. Alternatively, the catalyst may be a "heterogeneous" catalyst, meaning that the catalyst is insoluble in the reaction solution and remains a separate phase from the reactants in the reaction solution. Homogeneous catalysts are often desirable because they tend to achieve faster reaction rates because they more readily come into intimate contact with the reactants in the reaction mixture than heterogeneous catalysts. However, heterogeneous catalysts have the desirable characteristic of being easier to separate from the reaction solution after the reaction is complete than homogeneous catalysts. Removal of homogeneous catalysts often requires neutralization to form undesirable salts. Heterogeneous catalysts can be separated, for example, by decantation or filtration.

[0004] Acid catalysts and base catalysts are not used simultaneously because they tend to react with each other and destroy (neutralize) each other's catalytic functions. Thus, a two-stage polycondensation reaction can include multiple stages, including performing a hydrolysis reaction using an acid catalyst, neutralizing and removing the acid catalyst from the hydrolysis reaction mixture, adding a base catalyst for the condensation reaction, and then neutralizing and removing the base catalyst from the polycondensation reaction product.

[0005] It would be desirable to identify a method for preparing polysiloxanes starting from alkoxysilanes and / or alkoxysiloxanes by polycondensation using a process that utilizes a heterogeneous catalyst to benefit from the fast reaction rate of a homogeneous catalyst system, but also the ease and efficiency of isolating the catalyst when the reaction is complete. It would also be desirable to identify a method that allows for the simultaneous presence of both an acid catalyst and a base catalyst throughout both the hydrolysis and condensation reactions, without the need to remove one catalyst after the hydrolysis reaction and add another for the condensation reaction. The simultaneous use of catalysts simplifies the two-step polycondensation reaction procedure. Summary of the Invention

[0006] The present invention provides a solution for finding a method for preparing polysiloxanes starting from alkoxysilanes and / or alkoxysiloxanes by polycondensation using a process that uses a heterogeneous catalyst to benefit from the fast reaction rate of a homogeneous catalyst system, but also from the ease and efficiency of isolating the catalyst when the reaction is complete. Furthermore, the present invention allows for the simultaneous presence of both an acid catalyst and a base catalyst throughout both the hydrolysis and condensation reactions, without the need to remove one catalyst after the hydrolysis reaction and add another for the condensation reaction. Furthermore, the present invention allows for the simultaneous use of an acid catalyst and a base catalyst without material inhibition of the catalytic properties of the acid catalyst and the base catalyst.

[0007] The present invention is the result of the discovery that gel-type heterogeneous acid catalysts and gel-type heterogeneous base catalysts, such as those typically used as ion exchange resins, can coexist in a polycondensation reaction solution without neutralizing their acid and base functional groups, and can also effectively catalyze the polycondensation of alkoxysilanes and / or alkoxysiloxanes via hydrolysis and condensation at rates at least as fast as using a two-stage homogeneous catalytic process.

[0008] Surprisingly, it has been found that gel-type heterogeneous catalysts can achieve these results independently as acid and base catalysts simultaneously present in the polycondensation reaction of alkoxysilanes and / or alkoxysiloxanes.As shown in the Examples section below, for example, macroporous heterogeneous ion exchange resins do not have the same effect.Even more surprisingly, the sequential addition of gel-type heterogeneous catalysts did not work as well as sequential homogeneous catalysis or the simultaneous use of gel-type heterogeneous acid and base catalysts (it took longer and the reaction was less complete).Therefore, the simultaneous presence of heterogeneous gel-type acid and base catalysts during the hydrolysis and condensation of alkoxysilanes and / or alkoxysiloxanes results in synergistic performance of the overall polycondensation reaction.

[0009] In a first aspect, the present invention is a process for preparing polysiloxanes, comprising a two-part polycondensation of alkoxysilanes and / or alkoxysiloxanes, including the steps of: (a) hydrolyzing alkoxysilanes and / or alkoxysiloxanes to hydroxyl-functional silanes and / or hydroxyl-functional siloxanes; and (b) condensing the hydroxyl-functional silanes and / or hydroxyl-functional siloxanes to form a polysiloxane polycondensation product, characterized in having both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst simultaneously present during both the hydrolysis and condensation steps.

[0010] In a second aspect, the present invention is a composition simultaneously comprising: (a) reactants selected from alkoxysilanes and / or alkoxysiloxanes, and / or siloxane polycondensation reaction products of alkoxysilanes and / or alkoxysiloxanes; (b) a gel-type heterogeneous acid catalyst; (c) a gel-type heterogeneous base catalyst; and (d) water.

[0011] The present invention is useful for preparing polysiloxanes from alkoxysilanes and / or alkoxysiloxanes. DETAILED DESCRIPTION OF THE INVENTION

[0012] Test methods, unless a date is given with the test method number, refer to the test method most recent as of the priority date of this document. Reference to a test method includes both a reference to the testing society and the test method number. The following test method abbreviations and designations apply herein: ASTM refers to the American Society for Testing and Materials, EN refers to European Norm, DIN refers to the Deutsches Institut fur Normung, and ISO refers to the International Organization for Standards.

[0013] "Plurality" means two or more. "And / or" means "and, or alternatively." All ranges are inclusive unless otherwise indicated. Identification of materials by trademark or trade name refers to materials having compositions sold under that trademark or trade name as of the priority date of this application.

[0014] General term “C x-y "," "C x -C y " and "Cx-Cy" are interchangeable in the context of chemical structures and refer to having x to y carbon atoms in the chemical structure.

[0015] "Heterogeneous catalyst" refers to a catalyst that is insoluble and therefore remains in particulate form in the reaction mixture that it catalyzes.

[0016] "Homogeneous catalyst" refers to a catalyst that is soluble in the reaction mixture.

[0017] "Gel-type resin" refers to a resin in particulate form, particularly in a non-solvent swollen state, that does not contain pore structures with pore sizes greater than 2 angstroms, typically greater than 1 angstrom, that penetrate through the surface and extend through the resin particle, and that may not contain pore structures with pore sizes greater than 0.5 angstroms, and may not contain any pore structures that penetrate through the surface and extend through the resin particle. Gel-type resins swell appreciably (change volume) in polar solvents upon absorption of the polar solvent, and typically become translucent upon solvent swelling. Gel-type resins are also known as microporous resins in the ion exchange field.

[0018] A "gel-type heterogeneous catalyst" refers to a gel-type resin, typically in particulate form, that acts as a heterogeneous catalyst. A "gel-type heterogeneous acid catalyst" is a gel-type resin with acidic chemical functional groups that acts as a heterogeneous acid catalyst. A "gel-type heterogeneous base catalyst" is a gel-type resin with basic chemical functional groups that acts as a heterogeneous base catalyst.

[0019] "Macroporous resin," also known as macroreticular resin, refers to a resin in particulate form having a well-defined pore structure penetrating the surface and extending throughout the resin, typically with pore diameters greater than 2 angstroms, typically greater than 50 angstroms, and even more typically greater than 100 angstroms, present regardless of the presence of solvent. Macroporous resins typically have a higher crosslink density than gel-type resins, and as a result, do not swell appreciably, or even at all, in the presence of polar solvents.

[0020] A "macroporous heterogeneous catalyst" refers to a macroporous resin that acts as a heterogeneous catalyst. A "macroporous heterogeneous acid catalyst" is a macroporous resin with acidic chemical functionality that acts as a heterogeneous acid catalyst. A "macroporous heterogeneous base catalyst" is a macroporous resin with basic chemical functionality that acts as a heterogeneous base catalyst.

[0021] "Silane" refers to a group of compounds having the general formula: R a SiY (4-a) (In the formula, R a is hydrogen, alkyl, substituted alkyl, aryl alkyl, substituted aryl alkyl, aryl, and substituted aryl. The alkyl and substituted alkyl groups each independently typically contain 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, or even 7 or more carbon atoms, but typically contain 8 or fewer carbon atoms, and can contain 7 or fewer, 6 or fewer, 5 or fewer, 4 or fewer, 3 or fewer, or even 2 or fewer carbon atoms. At least one Y is alkoxyl for "alkoxy-functional silanes," and at least one Y is hydroxyl for "hydroxyl-functional silanes."

[0022] "Siloxane" refers to a molecule containing at least one siloxane (Si-O-Si) bond. As used herein, "siloxane" can refer to a "polysiloxane" having multiple siloxane bonds, or a siloxane having only one siloxane bond. The term "polysiloxane" is used to refer to a siloxane having more than one siloxane bond. Polysiloxanes can have linear, cyclic, ladder, and three-dimensional network structures.

[0023] Polysiloxanes comprise a plurality of siloxane units linked together through siloxane bonds. The siloxane units can be characterized by the designations M, D, T, and Q. M represents a group of the formula "(CH3)3SiO 1 / 2 " D refers to a siloxane unit having the formula "(CH3)2SiO 2 / 2" T refers to a siloxane unit having the formula "(CH3)SiO 3 / 2 ". Q refers to a siloxane unit having the formula "SiO 4 / 2 " refers to siloxane units having the subscript "1 / 2". Non-oxygen groups bonded to silicon atoms in M, D, and T units are methyl groups unless otherwise stated or indicated. In particular, an oxygen atom having a subscript of "1 / 2" indicates that the oxygen bridges the designated atom to a second atom, in which case the second atom is also designated with an oxygen subscript of "1 / 2" to form a siloxane bond. For example, ((CH3)3SiO 1 / 2 )(SiO 4 / 2 ) or MQ refers to an M unit bonded to a Q unit where an oxygen atom is shared between the silicon atom of the M unit and the silicon atom of the Q unit. The subscript 1 / 2 multiplier indicates how many oxygen atoms are in such a shared bonding arrangement with the silicon atom of the siloxane unit.

[0024] Reference to the designation of a siloxane unit with the suffix "type" refers to a siloxane unit in which any one or more methyl groups are actually R groups (where R is a group other than methyl, such as hydroxyl, alkoxyl, or hydrocarbyl). Hydrocarbyls typically contain 1 to 8 carbon atoms. For example, R can be methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or octyl.

[0025] A siloxane unit may include, as a superscript, a designation of a group bonded to the silicon atom in place of an alkyl group. For example, "M H The "R" type unit is an M type unit in which one R group is replaced with hydrogen: ((R 1 )2HSiO 1 / 2 ) refers to "M H " unit is an M unit in which one methyl is replaced with a hydrogen atom ((CH3)2HSiO 1 / 2 ) refers to T Ph The unit refers to a T unit in which a methyl group has been replaced with a phenyl group.

[0026] Chemical formula representations of polysiloxanes using the abbreviations M, D, T, and Q typically have subscripts associated with the unit identifiers that can refer to either the average molar ratio of that siloxane unit to all siloxane units in the molecule or the average number of related siloxane units in the molecule. When the subscript associated with a siloxane unit is 1 or greater, the subscript refers to the average number of those siloxane units in the molecule. When the subscript associated with a siloxane unit is less than 1, the subscript refers to the average molar ratio of that siloxane unit to the number of moles of all siloxane units in the molecule. The absence of a subscript means that the value of the subscript is 1.

[0027] An "OZ" site refers to a combination of hydroxyl and alkoxyl groups bonded to a silicon atom. The total number of OZ sites in a molecule or reaction mixture refers to the total number of combinations of hydroxyl and alkoxyl groups bonded to silicon atoms present in the molecule or reaction mixture. The OZ content of a material is reported as mole percent (mol%) relative to the moles of silicon atoms in the molecule.

[0028] The process of the present invention involves a two-part polycondensation of alkoxysilanes and / or alkoxysiloxanes.

[0029] Alkoxysilanes have the general structure (RO) x R' (4-x) Si, where the subscript x has an average value of 1 or greater, 2 or greater, or even 3 or greater, but also has an average value of 4 or less, 3 or less, or even 2 or less, and each R and R′ in each occurrence is independently selected from the group consisting of C1-C8 alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl groups), substituted C1-C8 alkyl groups, aryl groups, and substituted aryl groups.

[0030] The alkoxysiloxane can have one or more siloxane bonds and can include one or more alkoxyl groups bonded to at least one silicon atom. The alkoxyl groups are as described for the (RO) group of the alkoxysilane. The alkoxysiloxane can be linear, branched, resinous, or any other structure possible for a polysiloxane.

[0031] "Two-part" polycondensation refers to a process that involves two reactions to achieve polycondensation: a hydrolysis reaction and a condensation reaction. The hydrolysis and condensation reactions may occur sequentially or simultaneously. Typically, an alkoxysilane / siloxane undergoes hydrolysis to form a hydroxyl-functional silane or a hydroxyl-functional siloxane, respectively. The hydroxyl-functional silane and / or siloxane then undergoes condensation to form a polysiloxane. The polysiloxane is the polycondensation product of the two-part polycondensation.

[0032] The process of the present invention is characterized by having both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst present simultaneously throughout both the hydrolysis step and the condensation step. This process typically involves adding both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst to a reaction mixture containing alkoxysilanes and / or alkoxysiloxanes prior to the hydrolysis reaction step, and maintaining the catalysts therein throughout the condensation reaction step. Preferably, the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst are blended together before being added to the reaction mixture for the hydrolysis reaction, and maintained in the reaction mixture throughout the condensation reaction.

[0033] Surprisingly, the combination of a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst catalyzes both the hydrolysis and condensation reactions, and is a better catalyst than when only the gel-type heterogeneous acid catalyst is used for the hydrolysis and the gel-type heterogeneous base catalyst is added to the condensation reaction. The combination of a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst also results in at least as extensive polymerization to form polycondensation products as the more typical sequential use of a homogeneous acid catalyst followed by a homogeneous base catalyst, as shown in the experimental section by the fact that more "OZ" sites in the reaction mixture react and polycondensation products of higher molecular weight and viscosity are obtained under the same reaction conditions for the same time. The extent of the polycondensation reaction of the present invention further surprisingly suggests that the combination of a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst can occur without neutralizing the acid and base groups on each catalyst.

[0034] Gel-type heterogeneous acid catalysts and gel-type heterogeneous base catalysts are desirably solvent-swollen when used in the present process. Solvent swelling means that their volume increases by absorbing a solvent. Typically, the solvent is a polar solvent such as water or, preferably, an alcohol (e.g., ethanol). Solvent-swollen gels function as more efficient catalysts than non-swollen gels because reactants can penetrate the solvent-swollen gel more easily than non-swollen gels. It is useful for reactants to penetrate the gel so that more acid or base functional sites on the gel are exposed. Therefore, swelling a gel-type heterogeneous catalyst with a solvent makes more of the catalyst's acid and base sites available to the reactants than if the gel-type catalyst were not swollen. In contrast, microporous resin catalysts have defined pores that allow reactants to penetrate without solvent swelling.

[0035] The reaction mixture for hydrolysis typically contains water in addition to the alkoxysilane and / or alkoxysiloxane and the heterogeneous catalyst described hereinabove. The presence of one or more additional solvents is desirable, but not essential. The additional solvent can be selected from polar solvents, including, for example, alcohols (such as ethanol). The additional solvent is desirably present throughout both the hydrolysis reaction and the condensation reaction.

[0036] The process can be a batch, continuous, or semi-continuous process. In a batch process, all reactants reside in a single reaction vessel from the beginning to the end of the reaction, and the reaction mixture is typically stirred (or otherwise agitated) to maintain a suspension (slurry) of the heterogeneous catalyst throughout the hydrolysis and condensation reactions to maximize efficient contact with the catalyst particles. In a continuous process, the reactants flow continuously through a reactor or reactors as they react to form product, which then flows continuously from the reactor. Semi-continuous processes can take many different forms, including batch-like as well as continuous modes. For example, one semi-continuous process involves a series of batch reactors, where the reactants reside in one reactor for a period of time and then flow into another reactor for a period of time.

[0037] An example of a continuous process is a fixed-bed column process. For example, a reaction mixture containing alkoxysilanes and / or alkoxysiloxanes, water, and optionally a solvent can be passed through a column containing a physical mixture of a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst as the stationary phase. Then, as the reaction mixture passes through the column and comes into contact with the heterogeneous catalyst, the hydrolysis and condensation reactions occur.

[0038] Desirably, the process of the present invention involves heating the reaction mixture during the hydrolysis, condensation, or both the hydrolysis and condensation. During the reaction of the process, it is typically desirable to have a reaction mixture temperature of 30 degrees Celsius (°C) or higher, 40°C or higher, 50°C or higher, 60°C or higher, 70°C or higher, or even 80°C or higher, while simultaneously heating to a temperature typically of 120°C or lower, 110°C or lower, 100°C or lower, 90°C or lower, or even 80°C or lower. Heating can be accomplished by applying a heat source to the reaction mixture. Alternatively, some reactions, such as the hydrolysis reaction, are exothermic, and the reaction mixture can be heated without the separate application of heat. Indeed, in some situations, it is desirable to control the temperature rise resulting from the exothermic reaction by cooling or mitigating the temperature of the reaction mixture in some manner (e.g., by metering water) to maintain the temperature within a desired range.

[0039] One desirable method for carrying out the process is by utilizing a co-feed / co-strip procedure during hydrolysis. The co-feed / co-strip procedure can be part of a batch, semi-continuous, or even continuous process, but is typically characteristic of batch or semi-continuous processes using a single reaction vessel. A by-product of the hydrolysis reaction is alcohol, which occupies reactor volume and can inhibit the hydrolysis reaction rate. In the co-feed / co-strip procedure, the hydrolysis reaction mixture of catalyst and reactants is heated in the reaction vessel sufficiently to volatilize the alcohol product and remove the alcohol vaporized during the reaction by condensing it in a collection vessel. The term "co-feed / co-strip" is used because typically, one or more reactants are fed to the reaction vessel while the alcohol is volatilizing and being removed (stripped from the reaction vessel). The alcohol removal and reactant addition can independently be continuous or intermittent and occur primarily during hydrolysis when the alcohol is being formed. The addition of reactants may be stopped once the reaction vessel contains the desired volume. Once the alcohol has stripped to the desired level, the stripping procedure (alcohol evaporation and removal) may be stopped. After reactant feeding and alcohol stripping have stopped, the reactants may simply be allowed to proceed, typically at reflux, for the desired time to complete the condensation reaction. If desired, additional catalyst may be added after alcohol stripping has stopped. For example, the reaction vessel may contain only a catalyst for hydrolysis during the co-feed / co-strip procedure, and then a condensation catalyst may be added when alcohol stripping has stopped. Of course, both a hydrolysis catalyst and a condensation catalyst may be present in the reaction vessel throughout the hydrolysis and condensation reactions. The co-feed / co-strip process may use a homogeneous catalyst, a heterogeneous catalyst, or a combination of both homogeneous and heterogeneous catalysts.

[0040] By removing the alcohol in the co-feed / co-strip procedure, reactor volume is conserved. The free reactor volume allows more reactants to be added to the reactor than would be possible if alcohol were left behind, meaning that more product can be produced in a single reactor than would be possible if alcohol were left behind. This is a significant advantage of the co-feed / co-strip procedure, which can allow for the production of more polycondensation product in a given reactor than a similar batch process that does not include alcohol stripping.

[0041] A desirable feature of the process of the present invention is that the catalyst is easily isolated from the reaction mixture and / or reaction product. In a continuous flow process in which the reaction mixture flows past a fixed catalyst, the extrudate from the process is already catalyst-free and contains the reaction product. In a batch process, the gel-type heterogeneous acid catalyst and gel-type heterogeneous base catalyst are easily isolated from the reaction mixture and / or product by, for example, allowing the heterogeneous catalyst to phase separate (settle) from the solution and decanting the supernatant solution containing the reactants and / or product, or draining the catalyst from the supernatant in a separatory funnel or the like. Alternatively, the gel-type heterogeneous acid catalyst and gel-type heterogeneous base catalyst can be isolated using filtration. Once isolated, the gel-type heterogeneous acid catalyst and gel-type heterogeneous base catalyst can desirably be reused in the process of the present invention, typically without the need to replenish the acid and base functional sites on the catalyst. The isolated catalyst may be rinsed to remove undesirable components before subsequent use.

[0042] One embodiment of the batch process of the present invention includes the following steps.

[0043] First, (i) a solvent-swollen blend of a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst as a catalyst blend, (ii) a catalyst having the general formula: (RO) x R' (4-x)A reaction mixture is provided comprising: a silane having Si (where x has an average value of 1 or more, 2 or more, or even 3 or more, but simultaneously has an average value of 4 or less, 3 or less, or even 2 or less; and each R and R′ in each occurrence is independently selected from the group consisting of alkyl groups, substituted alkyl groups, aryl groups, and substituted aryl groups); and (iii) water. The alkyl groups and substituted alkyl groups independently typically contain 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, or even 7 or more carbon atoms, but simultaneously typically contain 12 or less, 10 or less, 8 or less, and may contain 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or even 2 or less carbon atoms. The reaction mixture can include a solvent, such as an alcohol (e.g., ethanol), and other liquid components as a continuous phase. The components can be combined in any order to form the reaction mixture. Some components may be metered in while the reactants are reacting. For example, water is typically metered during the hydrolysis rather than added all at once to help regulate the temperature of the reaction mixture and to prevent uncontrolled polymerization which could lead to gelation.

[0044] Second, the reaction mixture is stirred (e.g., stirred) to establish and maintain a slurry of the components, optionally while heating the reaction mixture. Stirring may begin while the components of the reaction mixture are being combined in the first step, or may begin after all of the components of the reaction mixture are combined. Stirring is desirably continued while the hydrolysis and condensation reactions occur in the mixture to form a product mixture. Stirring is desirably continued throughout the process until both the hydrolysis and condensation reactions have progressed to the desired extent.

[0045] Third, the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst are isolated from the remaining contents of the product mixture. In the broadest scope of this embodiment, there is no limitation on the method for isolating the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst from the remaining contents. Examples of methods for isolating the catalyst include the methods described above.

[0046] Optionally, the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst can be recycled and used again in another reaction process of the present invention.

[0047] A distinctive feature of the present invention is the presence of both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst throughout the reaction process. Typically, the combination of an acid catalyst and a base catalyst during the reaction is avoided because they tend to react with each other and neutralize the acid and base functional groups of the catalyst. However, the present invention stems in part from the discovery that a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst can be combined without neutralizing the acid and base functional groups of the catalyst, respectively, at least to an extent sufficient to substantially inhibit their catalytic ability in the claimed process. In light of this discovery, the present invention further includes a composition simultaneously comprising: (a) Gel-type heterogeneous acid catalysts and gel-type heterogeneous base catalysts, (b) water; (c) a reactant selected from an alkoxysilane and / or an alkoxysiloxane; and (d) optionally, a solvent, for example a polar solvent such as ethanol.

[0048] In addition to or instead of reactants selected from alkoxysilanes and / or alkoxysiloxanes, the composition may include a siloxane polycondensation reaction product of an alkoxysilane and / or alkoxysiloxane. [Example]

[0049] Table 1 identifies the materials used in the following Examples (Ex) and Comparative Examples (Comp Ex). The gel-type heterogeneous catalyst is swelled in Solvent 2 prior to use. It should be noted that the use of Solvent 1 and Solvent 2 is expected to produce similar results and be interchangeable in the processes and procedures described herein below.

[0050] [Table 1] AMBERLYST, AMBERTEC, and AMBERLITE are trademarks of DDP Specialty Electronic Materials. DUPONT is a trademark of DUPONT Polymers, Inc. ** Similar results are expected by directly substituting the AMBERLYST BD20 material with materials available from DUPONT under the designation AMBERLYST 125 or AMBERLYST 131.

[0051] The Examples and Comparative Examples are prepared according to the following procedures. The resulting products are characterized for viscosity, weight average molecular weight (Mw), and total OZ content, as appropriate, using the procedures followed in the Examples and Comparative Examples. Table 2 provides a general summary of the compositions, reporting the component amounts in grams (g) for each sample, as well as product characterization for each Example and Comparative Example.

[0052] Comparative Example A - Sequentially, Homogeneous Acid Catalyst, Then Homogeneous Base Catalyst The following components were added to a batch kettle reactor to form a reaction mixture: 190.88 grams (g) of n-octyltriethoxysilane, 12.00 g of solvent 1, and 0.65 g of HCl homogeneous acid catalyst. Then, 14.18 g of water was fed (feeding at a rate of 0.178 milliliters / min) while mixing at 600 revolutions per minute (RPM) for 80 minutes at 25°C under a nitrogen blanket. During this time, hydrolysis and condensation reactions occurred, producing ethanol as a by-product. After the water addition was complete, the reaction mixture was heated to 77°C and refluxed for 2 hours. The reaction mixture was cooled to 25°C, and 0.65 g of the homogeneous base catalyst KOH was added to neutralize the HCl homogeneous acid catalyst and make the mixture basic. The reaction mixture was then heated to 77°C and refluxed for an additional 2 hours, during which time the reaction product "thickened" and increased in molecular weight. The solution is cooled to 25°C and 1.4 g of HCl homogeneous acid catalyst is added to neutralize the base. 0.40 g of CaCO3 neutralizing agent is added to neutralize the acid. At this point, two phases appear in the solution, which are separated using a separatory funnel. The upper phase contains ethanol, and the lower phase contains the silicone resin product (siloxane product). The lower phase is returned to the reactor and heated to 95°C to strip off any remaining ethanol under atmospheric conditions. The solution is heated to 130°C with a nitrogen sparge to complete the solvent stripping. Residual solvent is collected using a Dean-Stark trap. The resulting resin is cooled and characterized for viscosity, weight average molecular weight, and OZ content as Comparative Example A.

[0053] Comparative Example B - Simultaneous Macroporous Heterogeneous Acid and Base Catalysis A catalyst premix is ​​prepared by combining 17.64 g of macroporous heterogeneous acid catalyst 17D and 19.73 g of macroporous heterogeneous base catalyst A26.

[0054] The following components were added to a batch kettle reactor to form a reaction mixture: 190.58 grams (g) of n-octyltriethoxysilane, 11.71 g of solvent 1, and the catalyst premix. 0.57 g of water was then charged, followed by 14.18 g of water (feeding at a rate of 0.178 milliliters per minute) while mixing at 1000 RPM under a nitrogen blanket at 25°C for 80 minutes. During this time, hydrolysis and condensation reactions occurred, producing ethanol as a by-product. After water addition was complete, the reaction mixture was heated to 77°C and refluxed for 4 hours. During this time, 0.37 g of water was charged. The reaction mixture was cooled to 25°C to obtain a cloudy mixture. The reaction mixture was vacuum filtered using a Buchner funnel equipped with Fisher Scientific P4 filter paper to remove the solid acid and base catalysts. The filtrate was returned to the reactor and heated to 95°C to strip off the ethanol under atmospheric conditions. A Dean-Stark trap is used to collect residual solvent. The solution is heated to 130°C with a nitrogen sparge to complete solvent stripping. The resulting resin is cooled and characterized for viscosity, weight average molecular weight, and OZ content as Comparative Example B.

[0055] Comparative Example C - Sequentially, Acid Gel Type Heterogeneous Catalyst, Then Base Gel Type Heterogeneous Catalyst A dry (before swelling) mass of 20 g of gel-type heterogeneous acid catalyst BD20 swollen with solvent 2, 11.75 g of solvent 2, 190.79 g of n-octyltriethoxysilane, and 585 microliters of water were added to a batch kettle reactor, and then 14.18 g of water was fed (feeding at a rate of 0.178 milliliters / minute) under a nitrogen blanket at 70°C for 80 minutes while mixing at 600 revolutions per minute (RPM). During this time, hydrolysis and condensation reactions occurred, producing ethanol as a by-product. After the water addition was complete, the reaction mixture was heated to 77°C and refluxed for 4 hours, and 358 microliters of water was added while refluxing. The reaction mixture was cooled to 25°C and filtered using a Buchner funnel equipped with Fisher Scientific P4 filter paper to remove the gel-type heterogeneous acid catalyst, yielding filtrate 1.

[0056] A dry (before swelling) mass of 20.15 g of gel-type heterogeneous base catalyst 550A swollen with solvent 2, 11.71 g of solvent 2, and 177 g of filtrate 1 are added to a batch kettle reactor. While mixing at 600 RPM under a nitrogen blanket, the mixture is heated to 77°C and refluxed for 21 hours. The solution is cooled, and mixing is stopped to obtain a two-phase composition. The entire composition is filtered using a Buchner funnel equipped with Fisher Scientific P4 filter paper to remove the solid catalyst. The filtrate is returned to the batch kettle reactor and heated to 95°C to strip off the ethanol under atmospheric conditions. Residual solvent is collected using a Dean-Stark trap. It is then heated to 130°C to complete the solvent stripping while sparging with nitrogen. The resulting resin is cooled and characterized for viscosity, weight average molecular weight, and OZ content as Comparative Example C.

[0057] Example 1 - Simultaneous Acid Gel Type Heterogeneous Catalyst and Base Gel Type Heterogeneous Catalyst of Comparative Example C A catalyst premix is ​​prepared by combining and physically mixing 20 g of dry (unswollen) gel-type heterogeneous acid catalyst BD20 and 20 g of dry (unswollen) mass of gel-type heterogeneous base catalyst 550A. The physical mixture is swelled with solvent 2 to obtain a catalyst premix.

[0058] The catalyst premix, 11.69 g of solvent 2, 192.13 g of n-octyltriethoxysilane, and 585 microliters of water were added to a batch kettle reactor, followed by 14.18 g of water (feeding at a rate of 0.178 milliliters per minute) under a nitrogen blanket at 70°C for 80 minutes while mixing at 1000 revolutions per minute (RPM). During this time, hydrolysis and condensation reactions occurred, producing ethanol by-product. Upon completion of the water addition, the resulting solution was heated to 77°C, refluxed for 4 hours, and then cooled. Because it was difficult to filter the solution using a Buchner funnel equipped with Fisher Scientific P4 filter paper, a small amount of the solution was filtered using a polytetrafluoroethylene 0.45 micrometer syringe filter. The filtered solution was stripped to remove ethanol using a rotary evaporator. The viscosity, weight average molecular weight, and oz content were characterized as in Example 1.

[0059] Example 2 - Simultaneous Acid Gel-Type Heterogeneous Catalyst and Base Gel-Type Heterogeneous Catalyst 50 g (dry weight) of gel-type heterogeneous acid / base blend catalyst, pre-rinsed with water and dried under vacuum, then swollen with Solvent 2, 11.69 g of Solvent 2, 190.41 g of n-octyltriethoxysilane, and 585 microliters of water were added to a batch kettle reactor, and then 14.18 g of water was added (feeding at a rate of 0.178 milliliters / minute) under a nitrogen blanket at 70°C for 80 minutes while mixing at 600 revolutions per minute (RPM). An additional 20.39 g of Solvent 2 was added throughout the water addition process. During this time, hydrolysis and condensation reactions occurred, producing ethanol by-product. After water addition was complete, the resulting solution was heated to 77°C and refluxed for 4 hours while adding 341 microliters of water. The resulting solution was then cooled. The resulting solution was filtered through a Buchner funnel equipped with Fisher Scientific P4 filter paper to remove the catalyst. The catalyst is rinsed with toluene to extract the final product from the catalyst mixture. The extraction solution is stripped using a rotary evaporator to remove the toluene, yielding Example 2. The viscosity, weight average molecular weight, and OZ content are characterized as Example 2.

[0060] viscosity Determine the viscosity of the resin using a Brookfield Viscometer (Model LVDV-II+P) and spindle SC4-18 at a sample volume of 6.7 milliliters and a temperature of 25°C. Select the spindle, load the sample cup, and insert the cup into the small sample adapter. Connect the spindle to the instrument. Allow the sample to equilibrate to temperature for at least 10 minutes. Start the instrument motor, select a rotation speed that results in a torque range of 10-90%, and run for 3 minutes. Collect data on the run and stop the motor. Allow the sample to rest for 2 minutes. Repeat two more times for a total of three runs. Use the average viscosity of the three runs as the sample viscosity. Millipascals * seconds (milliPascals * seconds, mPa * Report viscosity in s).

[0061] Weight average molecular weight (Mw) The weight-average molecular weight of the resin sample was determined using gel permeation chromatography (GPC). Agilent Chemstation Method 3102 8B GPC 24-FEB-2012.M was used. The sample was degassed through a membrane. The pump was isocratic at 1 ml / min at 6-7 MPa. An autosampler was used at 10°C. One 5-micron Guard (50 mm x 7.5 mm) and two PL Gel 5-micron Mixed C (300 mm x 7.5 mm) (Fisher Part #50-010-6923) columns were used, maintained at 35°C. A refractive index detector was used at 35°C. The detector had an automatic valve that sent the material being analyzed to waste and all other materials to recycle. Tetrahydrofuran stabilized with 250 parts per million by weight of butylated hydroxytoluene (BHT) was the effluent of this system.

[0062] Prepare the samples by adding 1,000 microliters of HPLC-grade toluene to a gel chromatography vial along with 10 microliters of sample. Mix each sample using a vortex mixer. 6 Calibrate with polystyrene standards analyzed at Mp (Mp refers to the molecular weight of the highest peak). A total of 10 polystyrene standards are analyzed in duplicate injections. >0.999r 2 A logarithmic scale is used to provide

[0063] OZ content Silicon-29( 29 The OZ content of the resins was determined using Si (Si) nuclear magnetic resonance (NMR) spectroscopy. NMR spectra were collected using an Agilent 500 MHz DD2 (mi-MR-06) system equipped with a 16 mm silicone-free AutoX probe or on a Varian Inova NMR (mi-MR-04) spectrometer with a proton operating frequency of 400 MHz. Samples were prepared in deuterated chloroform containing 0.02 molar chromium(III) acetylacetonate (Cr(acac)3).

[0064] The OZ content is the sum of the moles of alkoxyl and hydroxyl groups bonded to silicon atoms, expressed as a percentage of the moles of silicon atoms in the molecule. The OZ content of a molecule can be determined by identifying the peaks corresponding to the different siloxane units (M, D, and T) based on predetermined assignments known in the art and integrating these peaks to determine the relative molar concentrations of the functional groups. 29 The OZ content is determined from the Si NMR spectrum and is the sum of the molar concentrations of each functional group multiplied by the number of OZ groups associated with each functional group.

[0065] [Table 2] * Dry weight (non-solvent swollen weight)

[0066] Comparative Example A serves as a benchmark for a typical sequential homogeneous catalytic process for producing polycondensed siloxane products. It is desirable to achieve similar or better (same or higher viscosity, same or lower OZ content, and same or higher Mw) to this benchmark using the same reaction time.

[0067] Comparative Example B shows that simultaneous macroporous heterogeneous acid and base catalysts cannot achieve the desired results of equal or higher viscosity, equal or lower OZ content, and equal or higher Mw compared to Comparative Example A, even with twice the reaction time of Comparative Example A.

[0068] Comparative Example C shows that the sequential use of acid and then base gel-type heterogeneous catalysts does not achieve the desired results of equal or higher viscosity, equal or lower OZ content, and equal or higher Mw compared to Comparative Example A, even at six times the reaction time of the benchmark Comparative Example A.

[0069] Example 1 uses the same composition as Comparative Example C, except that a catalyst is simultaneously used throughout the process. Surprisingly, this process achieves the desired results of equal or higher viscosity, equal or lower OZ content, and equal or higher Mw compared to Comparative Example A in the same reaction time.

[0070] Example 2 is a repeat of Example 1, except that a different gel-type heterogeneous catalyst is simultaneously used throughout the process. Surprisingly, this process also achieves the desired results of equal or higher viscosity, equal or lower OZ content, and equal or higher Mw compared to Comparative Example A in the same reaction time. The present invention can provide the following aspects. [1] 1. A process for preparing polysiloxanes, said process comprising a two-part polycondensation of alkoxysilanes and / or alkoxysiloxanes, said process comprising: (a) hydrolyzing the alkoxysilanes and / or the alkoxysiloxanes to hydroxyl-functional silanes and / or hydroxyl-functional siloxanes; (b) condensing the hydroxyl-functional silane and / or the hydroxyl-functional siloxane to form a polysiloxane polycondensation product; Including, 10. A process characterized in that said process has both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst simultaneously present throughout both said hydrolysis step and said condensation step. [2] The process according to [1] above, wherein the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst are each swollen in a polar solvent. [3] The process according to [1] or [2] above, wherein the process is polycondensation of alkoxysilanes. [4] The alkoxysilane has the general formula: (RO) x R’ (4-x) The process of [3] above, wherein the compound has Si, wherein the subscript x is a value ranging from 1 to 4, and each R and R' in each occurrence is independently selected from the group consisting of a C1-C8 alkyl group, a substituted C1-C8 alkyl group, an aryl group, and a substituted aryl group. [5] The process according to any one of the above [1] to [4], wherein the polycondensation occurs in a reaction vessel as a batch reaction or as a continuous flow reaction through a fixed-bed reaction column comprising a fixed bed containing a physical mixture of the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst. [6] The process according to any one of [1] to [5] above, further comprising isolating the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst from the reaction product after the reaction is completed. [7] The process according to [6] above, wherein the process comprises filtering and / or settling the heterogeneous catalyst, and then decanting the liquid supernatant and / or removing the settled catalyst from the liquid supernatant. [8] The process according to the above [6] or [7], wherein the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst are reused in another process of the present invention after isolation without replenishing the acid sites and / or base sites of the catalyst. [9] The process comprises: (a) i. A solvent swollen blend of a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst as a catalyst blend; ii.General formula: (RO) x R’ (4-x) a silane having the formula Si, wherein x is a value ranging from 1 to 4, and each R and R′ in each occurrence is independently selected from the group consisting of a C1-C8 alkyl group, a substituted C1-C8 alkyl group, an aryl group, and a substituted aryl group; and iii.Water, providing a reaction mixture comprising: (b) mixing the reaction mixture, optionally with heating, to establish and maintain a slurry of the components while allowing hydrolysis and condensation reactions to occur in the reaction mixture to form a product mixture; (c) isolating the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst from the remainder of the product mixture; The process according to [1] above, comprising:

[10] at the same time, (a) reactants selected from alkoxysilanes and / or alkoxysiloxanes, and / or siloxane polycondensation reaction products of alkoxysilanes and / or alkoxysiloxanes; (b) a gel-type heterogeneous acid catalyst; (c) a gel-type heterogeneous base catalyst; (d) water.

Claims

1. 1. A process for preparing a polysiloxane, said process comprising: (a) hydrolyzing alkoxysilanes and / or alkoxysiloxanes to hydroxyl-functional silanes and / or hydroxyl-functional siloxanes; (b) condensing the hydroxyl-functional silane and / or the hydroxyl-functional siloxane to form a polysiloxane polycondensation product; Including, 10. A process characterized in that said process has both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst simultaneously present throughout both said hydrolysis step and said condensation step.

2. 2. The process of claim 1, wherein the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst each swell in a polar solvent.

3. 3. The process of claim 1 or 2, wherein the process is the polycondensation of alkoxysilanes.

4. The alkoxysilane has the general formula: (RO) ｘ R' （４－ｘ） Si, wherein the subscript x is a value ranging from 1 to 4, and each R and R' in each occurrence is independently selected from the group consisting of a C1-C8 alkyl group, a substituted C1-C8 alkyl group, an aryl group, and a substituted aryl group.

5. 3. The process of claim 1 or 2, wherein the polycondensation occurs in a reaction vessel as a batch reaction or as a continuous flow reaction through a fixed bed reaction column comprising a fixed bed containing a physical mixture of the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst.

6. 3. The process of claim 1 or 2, further comprising isolating the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst from the reaction product after both the hydrolysis reaction and the condensation reaction are completed.

7. 7. The process of claim 6, wherein the process comprises filtering and / or settling the heterogeneous catalyst and then decanting the liquid supernatant and / or removing the settled catalyst from the liquid supernatant.

8. 7. The process of claim 6, wherein the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst are reused in another process of the present invention after isolation without replenishing the acid sites and / or base sites of the catalyst.

9. The process comprises: (a) i. A solvent swollen blend of a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst as a catalyst blend; ii. General formula: (RO) ｘ R' （４－ｘ） a silane having the formula Si, wherein x is a value ranging from 1 to 4, and each R and R′ in each occurrence is independently selected from the group consisting of a C1-C8 alkyl group, a substituted C1-C8 alkyl group, an aryl group, and a substituted aryl group; and iii. water, providing a reaction mixture comprising: (b) mixing the reaction mixture, optionally with heating, to establish and maintain a slurry of the components while allowing hydrolysis and condensation reactions to occur in the reaction mixture to form a product mixture; (c) isolating the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst from the remainder of the product mixture content; 2. The process of claim 1, comprising:

10. at the same time, (a) reactants selected from alkoxysilanes and / or alkoxysiloxanes, and / or siloxane polycondensation reaction products of alkoxysilanes and / or alkoxysiloxanes; (b) a gel-type heterogeneous acid catalyst; (c) a gel-type heterogeneous base catalyst; (d) water.

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