Polycondensation Preparation of Polysiloxane Using Acid Catalyst / Base Catalyst 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 polysiloxane by a polycondensation reaction including a hydrolysis reaction and a condensation reaction that occur due to the simultaneous presence of a gel-type heterogeneous acid catalyst and a base catalyst.

[0002] Introduction One route for preparing polysiloxane is via a two-step polycondensation reaction of alkoxysilane and / or alkoxysiloxane. The first step requires hydrolysis of alkoxysilane and / or alkoxysiloxane to form hydroxy-functional silane and / or siloxane. The second step requires polycondensation of hydroxy-functional silane and / or siloxane. Acid catalysts 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, which means that the catalyst forms a homogeneous solution with the reaction solution. Alternatively, the catalyst may be a "heterogeneous" catalyst, which means that the catalyst is insoluble in the reaction solution and remains in a phase separated from the reactants in the reaction solution. A homogeneous catalyst is often desirable because it tends to achieve a faster reaction rate since it can more easily and closely contact the reactants in the reaction mixture than a heterogeneous catalyst. However, a heterogeneous catalyst has the desirable feature that it is easier to separate from the reaction solution after the reaction is completed than a homogeneous catalyst. The removal of a homogeneous catalyst often requires neutralization to form unwanted salts. A heterogeneous catalyst can be separated, for example, by decantation or filtration.

[0004] Since acid catalysts and base catalysts tend to react with each other and mutually destroy their catalytic functions (neutralize), they are not used simultaneously. Therefore, the two-step polycondensation reaction can include a plurality of steps including performing a hydrolysis reaction using an acid catalyst, neutralizing the acid catalyst and removing it from the hydrolysis reaction mixture, adding a base catalyst for the condensation reaction, and then neutralizing the base catalyst and removing it from the polycondensation reaction product.

[0005] It is desirable to specify a method for preparing polysiloxane starting from alkoxysilane and / or alkoxysiloxane by polycondensation using a process that benefits from the fast reaction rate of a homogeneous catalyst system but uses a heterogeneous catalyst to benefit from the ease and efficiency of catalyst isolation when the reaction is complete. Further, it is desirable to specify a method that allows both an acid catalyst and a base catalyst to be present simultaneously throughout both the hydrolysis reaction and the condensation reaction without the need to remove one catalyst after the hydrolysis reaction and add another catalyst for the condensation reaction. Using the catalysts simultaneously simplifies the two-step polycondensation reaction procedure.

Summary of the Invention

[0006] The present invention provides a solution for finding a method for preparing polysiloxane starting from alkoxysilane and / or alkoxysiloxane by polycondensation using a process that benefits from the fast reaction rate of a homogeneous catalyst system but uses a heterogeneous catalyst to benefit from the ease and efficiency of catalyst isolation when the reaction is complete. Further, the present invention enables both an acid catalyst and a base catalyst to be present simultaneously throughout both the hydrolysis reaction and the condensation reaction without the need to remove one catalyst after the hydrolysis reaction and add another catalyst for the condensation reaction. Further, in the present invention, it is possible to use an acid catalyst and a base catalyst simultaneously without causing material inhibition of the catalytic properties of the acid catalyst and the base catalyst.

[0007] The present invention has found 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 effectively catalyze the polycondensation of alkoxysilanes and / or alkoxysiloxanes via hydrolysis and condensation at least at the same rate as using a two-step homogeneous catalyst process.

[0008] Surprisingly, it has been found that gel-type heterogeneous catalysts can uniquely achieve these results as acid and base catalysts simultaneously present in the polycondensation reaction of alkoxysilanes and / or alkoxysiloxanes. As shown in the Examples section below of this specification, 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 function as well as the sequential homogeneous catalytic reaction or the simultaneous use of gel-type heterogeneous acid and base catalysts (it took more time and the reaction was more incomplete). Therefore, the simultaneous presence of heterogeneous gel-type heterogeneous acid and base catalysts during the hydrolysis and condensation of alkoxysilanes and / or alkoxysiloxanes results in a synergistic performance of the entire polycondensation reaction.

[0009] In a first aspect, the present invention is a process for preparing polysiloxane, comprising: (a) hydrolyzing an alkoxysilane and / or an alkoxysiloxane to a hydroxyl-functional silane and / or a hydroxyl-functional siloxane; and (b) condensing the hydroxyl-functional silane and / or the hydroxyl-functional siloxane to form a polysiloxane polycondensation product, the process comprising a two-part polycondensation of the alkoxysilane and / or the alkoxysiloxane, and 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.

[0010] In a second aspect, the present invention is a composition that simultaneously includes (a) a reactant selected from an alkoxysilane and / or an alkoxysiloxane, and / or a siloxane polycondensation reaction product of an alkoxysilane and / or an alkoxysiloxane, (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 polysiloxane from an alkoxysilane and / or an alkoxysiloxane.

Embodiments for Carrying Out the Invention

[0012] If the date is not indicated together with the test method number, the test method refers to the most recent test method on the priority date of this document. References to test methods include both a reference to the test association and the test method number. The following abbreviations and aliases for test methods apply to this specification: ASTM refers to the American Society for Testing and Materials, EN refers to the 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 include the endpoints unless otherwise indicated. Identification of materials by trademark or trade name refers to materials having the composition sold under that trademark or trade name on the priority date of this application.

[0014] The 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] The term "heterogeneous catalyst" refers to a catalyst that is insoluble and thus remains in particulate form in the reaction mixture in which it acts as a catalyst.

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

[0017] The term "gel-type resin" refers to a resin in particulate form that does not contain a pore structure with pore diameters larger than those that penetrate through the surface and extend through the resin particles, especially in the non-solvent swollen state. The pore structure has a pore diameter greater than 2 angstroms, typically greater than 1 angstrom, and may not contain a pore structure with a pore diameter greater than 0.5 angstroms, and may not contain any pore structure that penetrates through the surface and extends through the resin particles. Gel-type resins swell (change in volume) noticeably when absorbing a polar solvent and typically become translucent when solvent-swollen. Gel-type resins are also known as microporous resins in the field of ion exchange.

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

[0019] The term "macroporous resin", also known as a macroporous resin, typically refers to a resin in particulate form having a pore structure with distinct boundaries that penetrate the surface and extend throughout the resin, with pore diameters greater than 2 angstroms, typically greater than 50 angstroms, and even more typically greater than 100 angstroms, and that exists regardless of the presence of a solvent. Macroporous resins typically have a higher crosslink density than gel-type resins and as a result, do not swell noticeably or may not swell at all in the presence of a polar solvent.

[0020] "Macro-porous heterogeneous catalyst" refers to a macro-porous resin that acts as a heterogeneous catalyst. "Macro-porous heterogeneous acid catalyst" is a macro-porous resin having an acidic chemical functional group that acts as a heterogeneous acid catalyst. "Macro-porous heterogeneous base catalyst" is a macro-porous resin having a basic chemical functional group that acts as a heterogeneous base catalyst.

[0021] "Silane" has the general formula: R a SiY (4-a) (wherein R a is hydrogen, alkyl, substituted alkyl, arylalkyl, substituted arylalkyl, aryl, and substituted aryl) and includes organosilanes. Alkyl groups 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, and even 7 or more carbon atoms, but at the same time typically contain 8 or fewer carbon atoms, and may contain 7 or fewer, 6 or fewer, 5 or fewer, 4 or fewer, 3 or fewer, and even 2 or fewer carbon atoms. At least one Y is alkoxyl for "alkoxy-functional silane", and at least one Y is hydroxyl for "hydroxyl-functional silane".

[0022] "Siloxane" refers to a molecule containing at least one siloxane (Si-O-Si) bond. In this specification, "siloxane" may be a "polysiloxane" having a plurality of siloxane bonds or a siloxane having only one siloxane bond. The term "polysiloxane" is used when meaning a siloxane having more than one siloxane bond. Polysiloxanes can have linear, cyclic, ladder-shaped, and three-dimensional network structures.

[0023] Polysiloxanes contain a plurality of siloxane units linked to each other via siloxane bonds. Siloxane units can be characterized by the notations M, D, T, and Q. M refers to a siloxane unit having the formula "(CH3)3SiO 1 / 2 ". D refers to a siloxane unit having the formula "(CH3)2SiO 2 / 2refers to a siloxane unit having 」. 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 」. Unless otherwise stated or indicated, the non-oxygen group bonded to the silicon atom in the M unit, D unit, and T unit is a methyl group. In particular, an oxygen atom with a subscript that is a multiple of 「1 / 2」 indicates that the oxygen bridges the designated atom to a second atom, in which case the second atom is also designated by an oxygen atom with a subscript that is a multiple 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 in which an oxygen atom is shared between the silicon atom of the M unit and the silicon atom of the Q unit. The multiplier of the subscript 1 / 2 indicates how many oxygen atoms are in such a shared bonding arrangement with the silicon atom of the siloxane unit.

[0024] A reference to the notation of a siloxane unit having the suffix 「type」 refers to a siloxane unit in which any one or more than one methyl group is actually an R group (R is a group other than methyl such as hydroxyl, alkoxyl, or hydrocarbyl). Hydrocarbyl typically contains 1 to 8 carbon atoms. For example, R can be methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or octyl.

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

[0026] The chemical formula notation of polysiloxanes using the abbreviations M, D, T, Q typically has a subscript associated with a unit identifier 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 total 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] The "OZ" moiety refers to a combination of a hydroxyl group and an alkoxyl group bonded to a silicon atom. The total number of OZ moieties 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 the double polycondensation of alkoxysilanes and / or alkoxysiloxanes.

[0029] An alkoxysilane has 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 simultaneously has an average value of 4 or less, 3 or less, or even 2 or less, and each R and R’ is independently selected, at each occurrence, 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] An alkoxysiloxane can have one or more siloxane bonds and can contain one or more alkoxyl groups bonded to at least one silicon atom. The alkoxyl group is as described for the (RO) group of an alkoxysilane. The alkoxysiloxane can be linear, branched, resinous, or any other structure possible for polysiloxanes.

[0031] “Bifunctional” polycondensation means a process that includes two reactions to achieve polycondensation, namely a hydrolysis reaction and a condensation reaction. The hydrolysis reaction and the condensation reaction may be carried out sequentially or simultaneously. Typically, an alkoxysilane / siloxane undergoes hydrolysis to form a hydroxyl-functional silane or a hydroxyl-functional siloxane, respectively. Then, the hydroxyl-functional silane and / or siloxane undergoes condensation to form a polysiloxane. The polysiloxane is the polycondensation product of bifunctional 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 includes adding both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst to a reaction mixture containing an alkoxysilane and / or an alkoxysiloxane before the hydrolysis reaction step and retaining 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 are 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 hydrolysis and condensation reactions, and the catalyst is superior to the case where only the gel-type heterogeneous acid catalyst is used for hydrolysis and the gel-type heterogeneous base catalyst is added to the condensation reaction. The combination of the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst also results in a polymerization as extensive as at least that of the more typical sequential use of a homogeneous acid catalyst followed by a homogeneous base catalyst, as can be seen from the fact that more "OZ" sites in the reaction mixture react in the experimental chapter and a polycondensation product of higher molecular weight and viscosity is obtained under the same reaction conditions over the same time, forming a polycondensation product. The degree of the polycondensation reaction of the present invention further surprisingly suggests that the combination of the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst exists without neutralizing the acid groups and base groups on the respective catalysts.

[0034] The gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst, when used in the present process, desirably swell in the solvent. Solvent swelling means an increase in volume by absorbing the solvent. Typically, the solvent is a polar solvent such as water or preferably an alcohol (e.g., ethanol). The solvent-swollen gel functions as a more efficient catalyst than the non-swollen gel because the reactants can penetrate the solvent-swollen gel more easily than the non-swollen gel. It is useful for the reactants to penetrate the gel so as to be exposed to more acid or base functional sites on the gel. Thus, swelling the gel-type heterogeneous catalyst with a solvent allows the reactants to utilize more of the acid and base sites of the catalyst than when the gel-type catalyst was not swollen. In contrast, the microporous resin catalyst has defined pores that allow the penetration of reactants without swelling in the solvent.

[0035] The reaction mixture for hydrolysis typically contains water in addition to an alkoxysilane and / or an alkoxysiloxane and the heterogeneous catalyst described above herein. It is desirable but not essential for there to be an additional single or multiple solvents present. The additional solvent can be selected from polar solvents such as alcohols (e.g., ethanol). It is desirable for the additional solvent to be present throughout both the hydrolysis reaction and the condensation reaction.

[0036] This process can be a batch process, a continuous process, or a semi - continuous process. In a batch process, all of the reactants are present within a single reaction vessel from the start 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 reaction and the condensation reaction in order to maximize efficient contact with the catalyst particles. In a continuous process, the reactants flow continuously through a reactor or multiple reactors as they react to form the product, and then the product flows continuously from the reactor. A semi - continuous process can take many different forms and includes both batch - like and continuous - like aspects. For example, one semi - continuous process includes a series of batch reactors, in which case the reactants are present within a particular reactor for a period of time and then flow into another reactor over a period of time.

[0037] An example of a continuous process is a fixed - bed column process. For example, a reaction mixture containing an alkoxysilane and / or an alkoxysiloxane, water, and optionally a solvent can flow 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 flows through the column and contacts the heterogeneous catalyst, hydrolysis and condensation reactions occur.

[0038] Desirably, the process of the present invention includes heating the reaction mixture during hydrolysis, condensation, or both hydrolysis and condensation. During the reaction of this 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. At the same time, it is typically heated to a temperature 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 carried out by applying a heat source to the reaction mixture. Alternatively, some reactions such as hydrolysis reactions are exothermic, and the reaction mixture can be heated without separately adding heat. In fact, in some situations, it is desirable to regulate the temperature rise resulting from the exothermic reaction by cooling or moderating the temperature of the reaction mixture in some way (e.g., by metering water) to keep the temperature within the desired range.

[0039] One desirable way to carry out the process is by utilizing a co-feed / costrip procedure during hydrolysis. The co-feed / costrip procedure can be part of a batch process, a semi-batch process, or even a continuous process, but is typically characteristic of a batch or semi-batch process that uses a single reaction vessel. The by-product of the hydrolysis reaction is alcohol, which can occupy reactor volume and inhibit the hydrolysis reaction rate. In the co-feed / costrip procedure, the hydrolysis reaction mixture of the catalyst and reactants is heated in the reaction vessel to such an extent that the alcohol product is volatilized and removed by condensing the alcohol that has volatilized during the reaction in a recovery vessel. Typically, one or more reactants are fed to the reaction vessel while the alcohol is being volatilized and removed (volatilizing from the reaction vessel), hence the term "co-feed / costrip". The removal of alcohol and the addition of reactants can each be continuous or intermittent, independently, and mainly occur during hydrolysis in which alcohol is being formed. The addition of reactants may stop once the reaction vessel contains the desired volume. The volatilization procedure (volatilization and removal of alcohol) may stop once the alcohol has volatilized to the desired level. After the supply of reactants and the volatilization of alcohol have stopped, the reactants may simply proceed for a desired time while refluxing to complete the condensation reaction. If desired, additional catalyst may be added after the alcohol volatilization has stopped. For example, the reaction vessel may contain only the catalyst for hydrolysis during the co-feed / costrip procedure and then add the condensation catalyst when the alcohol volatilization has stopped. Of course, both the hydrolysis catalyst and the condensation catalyst may be present in the reaction vessel throughout the hydrolysis reaction and the condensation reaction. The co-feed / costrip process can use a homogeneous catalyst, a heterogeneous catalyst, or a combination of both a homogeneous catalyst and a heterogeneous catalyst.

[0040] By removing alcohol in the co-feed / simultaneous volatilization procedure, reaction vessel volume is secured. The available reaction vessel volume allows more reactants to be added to the reaction vessel than could be added if alcohol remained, meaning that more product can be produced in a single reaction vessel than if alcohol were left behind. This is an important advantage of the co-feed / simultaneous volatilization procedure and enables the production of more polycondensation product in a given reaction vessel than similar batch processes that do not involve alcohol volatilization.

[0041] A desirable feature of the process of the present invention is that the catalyst is easily isolable from the reaction mixture and / or reaction product. In a continuous flow process where the reaction mixture flows through a fixed catalyst, the extrudate from the process already contains no catalyst and contains the reaction product. In a batch process, gel-type heterogeneous acid catalysts and gel-type heterogeneous base catalysts can be easily isolated from the reaction mixture and / or product, for example, by phase separating (sedimenting) the heterogeneous catalyst from the solution and decanting the supernatant solution containing the reactants and / or product, or by discharging the catalyst from the supernatant in a separating funnel or the like. Alternatively, gel-type heterogeneous acid catalysts and gel-type heterogeneous base catalysts can also be isolated using filtration. Once isolated, it is desirable that the gel-type heterogeneous acid catalysts and gel-type heterogeneous base catalysts can typically be reused in the process of the present invention without the need to replenish the acid and base functional sites on the catalyst. The isolated catalyst may then 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) the general formula: (RO) x R’ (4-x)Provide a reaction mixture comprising a silane having Si (wherein x has an average value of 1 or more, 2 or more, and further 3 or more, but at the same time has an average value of 4 or less, 3 or less, or further 2 or less), and each R and R' is independently selected from the group consisting of an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group at each occurrence), and (iii) water. 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, and further 7 or more carbon atoms, but at the same time typically contain 12 or less, 10 or less, 8 or less carbon atoms, and may contain 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, and further 2 or less carbon atoms. The reaction mixture can include a solvent such as an alcohol (e.g., ethanol) and other liquid components as the 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 in during hydrolysis rather than added all at once in order to help regulate the temperature of the reaction mixture and prevent uncontrolled polymerization that causes gelation.

[0044] Second, while optionally heating the reaction mixture, stir (e.g., agitate) the reaction mixture to establish and maintain a slurry of the components. Stirring may be started while combining the components of the reaction mixture in the first step or may be started after all the components of the reaction mixture have been combined. Desirably, continue stirring while causing hydrolysis and condensation reactions to occur in the mixture to form a product mixture. Desirably, continue stirring throughout the process until both the hydrolysis and condensation reactions have proceeded to the desired extent.

[0045] Third, isolate the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst from the remainder of the contents of the product mixture. In the broadest scope of this example, there is no limitation on the method for isolating the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst from the remainder of the 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 reused in another reaction process of the present invention.

[0047] A characteristic 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 to neutralize the acid and base functional groups of the catalyst. However, the present invention is partly due to the discovery that a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst can be combined to such an extent that they do not neutralize the acid and base functional groups of the catalyst and substantially inhibit their catalytic ability in at least the claimed process. In view of this discovery, the present invention further includes a composition simultaneously containing the following: (a) A gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst, (b) Water, (c) A reactant selected from alkoxysilane and / or alkoxysiloxane, and (d) Optionally, a solvent, such as a polar solvent like ethanol.

[0048] In addition to or in place of the reactant selected from alkoxysilane and / or alkoxysiloxane, the composition can include a siloxane polycondensation reaction product of alkoxysilane and / or alkoxysiloxane.

Examples

[0049] Table 1 reveals the materials used in the following examples (Ex) and comparative examples (Comp Ex). The gel-type heterogeneous catalyst is swollen in Solvent 2 before use. It should be noted that the use of Solvent 1 and Solvent 2 produces similar results and is expected to be interchangeable in the processes and procedures described below in this specification.

[0050]

Table 1

[0051] Examples and comparative examples are prepared according to the following procedure. Using the procedures according to the examples and comparative examples, the resulting products are appropriately characterized with respect to viscosity, weight average molecular weight (Mw), and total OZ content. Table 2 provides a general overview of the compositions reporting the amounts of components in grams (g) for each sample, as well as the characterization of the products for each example and comparative example.

[0052] Comparative Example A - Sequential, acid homogeneous catalyst, then base homogeneous catalyst Add the following components to a batch kettle reactor, namely, 190.88 grams (g) of n-octyltriethoxysilane, 12.00 g of Solvent 1, and 0.65 g of HCL homogeneous acid catalyst to form a reaction mixture. Then, while mixing at 600 revolutions per minute (RPM) at 25 °C for 80 minutes under a nitrogen blanket atmosphere, supply 14.18 g of water (supplied at a rate of 0.178 milliliters per minute). During this time, hydrolysis and condensation reactions occur, thereby producing ethanol as a by-product. When the addition of water is complete, heat the reaction mixture to 77 °C and reflux for 2 hours. Cool the reaction mixture to 25 °C, add 0.65 g of homogeneous base catalyst KOH to neutralize the HCL homogeneous acid catalyst, and make the mixture basic. Heat the reaction mixture to 77 °C and reflux for another 2 hours, during which the reaction product "thickens" and the molecular weight increases. Cool the solution to 25 °C, add 1.4 g of HCL homogeneous acid catalyst to neutralize the base. Add 0.40 g of CaCO3 neutralizer 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). Return the lower phase to the reactor, heat it to 95 °C, and volatilize any residual ethanol under atmospheric conditions. Heat the solution to 130 °C while nitrogen sparging to complete solvent volatilization. Use a Dean-Stark trap to recover the residual solvent. Cool the resulting resin and evaluate its viscosity, weight-average molecular weight, and OZ content as Comparative Example A.

[0053] Comparative Example B - Simultaneously, a macroporous heterogeneous acid catalyst and a base catalyst Prepare a catalyst premix by combining 17.64 g of macroporous type heterogeneous acid catalyst 17D and 19.73 g of macroporous type heterogeneous base catalyst A26.

[0054] Add the following components to a batch kettle reactor, namely, 190.58 grams (g) of n-octyltriethoxysilane, 11.71 g of Solvent 1, and a catalyst premix to form a reaction mixture. Charge 0.57 g of water, and then supply 14.18 g of water (supplied at a rate of 0.178 milliliters per minute) while mixing at 1000 RPM for 80 minutes at 25 °C under a nitrogen blanket atmosphere. During this time, hydrolysis and condensation reactions occur, thereby producing ethanol as a byproduct. Once the addition of water is complete, heat the reaction mixture to 77 °C and reflux for 4 hours. During this time, charge 0.37 g of water. Cool the reaction mixture to 25 °C to obtain a turbid mixture. Vacuum filter the reaction mixture using a Buchner funnel equipped with Fisher Scientific P4 filter paper to remove the solid acid catalyst and base catalyst. Return the filtrate to the reactor, heat to 95 °C, and volatilize ethanol under atmospheric conditions. Use a Dean-Stark trap to recover the residual solvent. Heat the solution to 130 °C while nitrogen sparging to complete solvent volatilization. Cool the resulting resin and characterize the viscosity, weight average molecular weight, and OZ content as Comparative Example B.

[0055] Comparative Example C - Sequentially, an acid gel-type heterogeneous catalyst, then a base gel-type heterogeneous catalyst Add 20 g of a dry (before swelling) mass of a gel-type heterogeneous acid catalyst BD20 swollen in Solvent 2, 11.75 g of Solvent 2, 190.79 g of n-octyltriethoxysilane, and 585 microliters of water to a batch kettle reactor, and then supply 14.18 g of water (supplied at a rate of 0.178 milliliters per minute) while mixing at 600 revolutions per minute (RPM) for 80 minutes at 70 °C under a nitrogen blanket atmosphere. During this time, hydrolysis and condensation reactions occur, thereby producing ethanol as a byproduct. Once the addition of water is complete, heat the reaction mixture to 77 °C and reflux for 4 hours, and add 358 microliters of water while refluxing. Cool the reaction mixture to 25 °C and filter using a Buchner funnel equipped with Fisher Scientific P4 filter paper to remove the gel-type heterogeneous acid catalyst and obtain Filtrate 1.

[0056] 20.15 g of dry (before swelling) mass 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, heated to 95 °C, and ethanol is volatilized under atmospheric conditions. The residual solvent is recovered using a Dean-Stark trap. Then, it is heated to 130 °C and solvent evaporation is completed while sparging with nitrogen. The resulting resin is cooled and its viscosity, weight average molecular weight, and OZ content are characterized and evaluated as Comparative Example C.

[0057] Example 1 - Simultaneously, the acid gel-type heterogeneous catalyst and base gel-type heterogeneous catalyst of Comparative Example C A catalyst premix is prepared by combining 20 g of dry (non-swollen) gel-type heterogeneous acid catalyst BD20 and 20 g of dry (non-swollen) mass of gel-type heterogeneous base catalyst 550A and physically mixing them. The physical mixture is swollen with solvent 2 to obtain a catalyst premix.

[0058] A catalyst precursor mixture, 11.69 g of Solvent 2, 192.13 g of n-octyltriethoxysilane, and 585 microliters of water are added to a batch kettle reactor. Then, while mixing at 1000 revolutions per minute (RPM) at 70 °C for 80 minutes under a nitrogen blanket atmosphere, 14.18 g of water is supplied (supplied at a rate of 0.178 milliliters per minute). During this time, hydrolysis and condensation reactions occur, and ethanol by-products are formed. When the addition of water is complete, the resulting solution is heated to 77 °C, refluxed for 4 hours, and then cooled. Since it is difficult to filter the solution with a Buchner funnel equipped with Fisher Scientific P4 filter paper, a small amount of the solution is filtered using a polytetrafluoroethylene 0.45 micrometer syringe filter. The filtered solution is volatilized using a rotary evaporator to remove ethanol. The viscosity, weight average molecular weight, and OZ content are characterized as Example 1.

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

[0060] Viscosity Using a Brookfield viscometer (Model LVDV-II+P) and spindle SC4-18, determine the viscosity of the resin 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. Equilibrate the sample to the temperature for at least 10 minutes. Start the instrument motor, select a rotational speed that provides a torque range of 10 - 90%, and operate for 3 minutes. Collect data regarding the operation and stop the motor. Let the sample stand for 2 minutes. Repeat two more times for a total of three operations. Use the average viscosity of the three operations as the sample viscosity. Millipascal * seconds (milliPascals * seconds, mPa * s) and report the viscosity in.

[0061] Weight-average molecular weight (Mw) Determine the weight-average molecular weight of the resin sample using gel permeation chromatography (GPC). Use the Agilent Chemstation method 3102 8B GPC 24-FEB-2012.M. Degas the sample through a membrane. The pump is isocratic at 1 milliliter / minute at a pressure of 6 - 7 megapascals. Use the autosampler at 10°C. Use a 1×5 micrometer Guard (50mm×7.5mm) and 2×PL gel 5 micrometer Mixed C (300mm×7.5mm) (Fisher Part#50-010-6923) column maintained at 35°C. Use a refractive index detector at 35°C. The detector has an automatic valve that sends the material being analyzed to waste and recycles everything else. Tetrahydrofuran stabilized with 250 parts per million by weight of butylated hydroxy toluene (BHT) is the effluent of this system.

[0062] Prepare the sample by adding 1000 microliters of HPLC-grade toluene to a gel chromatography vial along with 10 microliters of the sample. Mix each sample using a vortex mixer. Analyze and calibrate with polystyrene standards at 580 - 1.8×10 6 Mp (where Mp refers to the molecular weight of the highest peak) of polystyrene standards analyzed. Analyze a total of 10 polystyrene standards in two injections. >0.999r 2 Use a logarithmic scale to provide

[0063] OZ content Determine the OZ content of the resin using silicon-29 ( 29 Si) nuclear magnetic resonance (NMR) spectroscopy. Collect the NMR spectrum using an Agilent 500 megahertz DD2 (mi-MR-06) system equipped with a 16 mm silicon-free AutoX probe, or on a Varian Inova NMR (mi-MR-04) spectrometer with a proton operating frequency of 400 megahertz. Prepare the sample in deuterated chloroform containing 0.02 molar concentration of 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 relative to the moles of silicon atoms in the molecule. Identify the peaks corresponding to different siloxane units (M, D, and T) based on predetermined assignments known in the art, and integrate these peaks to determine the relative molar concentration of functional groups, thereby obtaining the OZ content from the 29 Si NMR spectrum of the molecule. The OZ content is the sum of the products of the molar concentration of each functional group multiplied by the number of OZ groups associated with each functional group.

[0065]

Table 2

[0066] Comparative Example A functions as a benchmark for a typical sequential homogeneous catalyst process for producing a polycondensed siloxane product. Using the same reaction time, it is desirable to achieve results that are the same as or better than this benchmark (equal or higher viscosity, equal or lower OZ content, and equal or higher Mw).

[0067] Comparative Example B shows that even with a reaction time twice that of Comparative Example A, the simultaneous use of a macroporous heterogeneous acid and base catalyst 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.

[0068] Comparative Example C shows that even with a reaction time six times that of the benchmark Comparative Example A, the sequential use of a gel-type heterogeneous acid and then base catalyst 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.

[0069] Example 1 uses the same composition as Comparative Example C, except that the catalyst is used simultaneously 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 at the same reaction time.

[0070] Example 2 is a repetition of Example 1, except that different gel-type heterogeneous catalysts are used simultaneously 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 at the same reaction time.

Claims

1. A process for preparing polysiloxane, said process comprising the bimolecular polycondensation of an alkoxysilane and / or an alkoxysiloxane, said process comprising: (a) hydrolyzing said alkoxysilane and / or said alkoxysiloxane to form a hydroxyl-functional silane and / or a hydroxyl-functional siloxane; (b) condensing said hydroxyl-functional silane and / or said hydroxyl-functional siloxane to form a polysiloxane polycondensation product; comprising: said process being characterized by having both a gel-type heterogeneous acid catalyst and a gel-type heterogeneous base catalyst present simultaneously throughout both said hydrolysis step and said condensation step.

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

3. The process according to claim 1 or 2, wherein said process is the polycondensation of an alkoxysilane.

4. wherein the alkoxysilane has the general formula: (RO) ｘ ｘ R' （４－ｘ） Si (wherein the subscript x is a value in the range of 1 to 4, and each R and R' 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 at each occurrence), the process according to claim 3.

5. Said 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 said gel-type heterogeneous acid catalyst and said gel-type heterogeneous base catalyst. The process according to any one of claims 1 to 4.

6. The process according to any one of claims 1 to 5, further comprising isolating said gel-type heterogeneous acid catalyst and said gel-type heterogeneous base catalyst from the reaction product after said reaction is completed.

7. The process according to claim 6, wherein said process comprises filtering and / or sedimenting said heterogeneous catalyst and then decanting the liquid supernatant and / or removing said sedimented catalyst from said liquid supernatant.

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

9. Said 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） Si (wherein x is a value in the range of 1 to 4, and each R and R' 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 at each occurrence), and iii. water; providing a reaction mixture comprising; (b) mixing said reaction mixture while optionally heating to effect hydrolysis and condensation reactions in said reaction mixture to form a product mixture while establishing and maintaining a slurry of components. Step (c) of isolating the gel-type heterogeneous acid catalyst and the gel-type heterogeneous base catalyst from the remainder of the contents of the product mixture; The process according to claim 1, comprising: **Claim 10** Simultaneously, (a) a reactant selected from an alkoxysilane and / or an alkoxysiloxane, and / or a siloxane polycondensation reaction product of an alkoxysilane and / or an alkoxysiloxane; (b) a gel-type heterogeneous acid catalyst; (c) a gel-type heterogeneous base catalyst; (d) water, and a composition containing the same.

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