Method for preparing a polyorganosiloxane copolymer

Abstract

A method that can be used to prepare a poly(dimethyl / methylvinyl)siloxane copolymer is provided. The method includes the use of Raman spectroscopy.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 352,260, filed on June 15, 2022, under 35 U.S.C. § 119(e). U.S. Provisional Patent Application No. 63 / 352,260 is incorporated herein by reference.

[0002] A method for preparing a polyorganosiloxane copolymer is disclosed. More particularly, the method produces a copolymer having a desired chain distribution of units of the formula R’RSiO 2 / 2 [wherein each R is a monovalent hydrocarbyl group or a halogenated hydrocarbyl group and each R’ is an alkenyl group](D Vi units).

[0003] Introduction U.S. Patent No. 3,183,209 discloses vinyl - containing organopolysiloxanes and procedures for their production. Vinyl - containing organopolysiloxanes can be prepared by heating decamethyltetrasiloxane and cyclic siloxanes, methylvinylcyclosiloxane, octamethylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane in the presence of potassium dimethylsilanolate.

[0004] NMR has been used to identify methyl vinyl siloxane copolymers, but real-time analysis of reaction mixtures to produce methyl vinyl siloxane copolymers on a commercial scale has the disadvantages of being difficult, expensive, and not practical to use NMR technology. Therefore, conventional processes may have the disadvantage of low productivity because, in order to minimize processing time, it may be desirable to stop the reaction when the desired product structure is reached or immediately thereafter. However, the time to reach the desired product structure may vary from batch to batch for various reasons, such as variations in process conditions such as the specific siloxanes selected as reactants and the temperature selected. As a result, the time required to obtain the desired product varies from batch to batch. SUMMARY OF THE INVENTION

[0005] A method for preparing a polyorganosiloxane copolymer is provided herein. The method comprises 1) A) a source of siloxane units of the formula (R2SiO 2 / 2 ), B) a source of siloxane units of the formula (RR’SiO 2 / 2 ) [wherein each R is independently selected from the group consisting of alkyl groups and halogenated alkyl groups, and R’ represents an alkenyl group], and C) a base catalyst, to form a mixture by combining starting materials comprising 2) stirring the mixture at a temperature sufficient to form a reaction mixture comprising a copolymer via an equilibration reaction, 3) using Raman spectroscopy to monitor a spectral region containing characteristic Raman bands corresponding to one or both of the concentration of decoupling (RR’SiO 2 / 2 ) units and the concentration of coupling (RR’SiO 2 / 2 ) units in the reaction mixture [wherein R and R’ are as defined above], and 4) stopping the equilibration reaction when a target value associated with the characteristic Raman band is reached.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0007] Step 1) of the method described herein involves forming a mixture by combining A) a source of siloxane units of formula (R2SiO 2 / 2 ), B) a source of siloxane units of formula (RR’SiO 2 / 2 ) [wherein each R is independently selected from the group consisting of alkyl groups and halogenated alkyl groups], and C) a base catalyst.

[0008] Starting materials A) and B) can be one or more polyorganosiloxanes, and the polyorganosiloxane has the unit formula: (R3SiO 1 / 2 ) t (R2R’SiO 1 / 2 ) u (R2SiO 2 / 2 ) v (RR’SiO 2 / 2 ) w (RSiO 3 / 2 ) x (R’SiO 3 / 2 ) y (SiO4 / 2 ) z [In the formula, the subscripted letters t, u, v, w, x, y, and z represent the amounts of each unit, and have average values such that t≧0, u≧0, v≧1, w≧1, x≧0, y≧0, z≧0, provided that the amount (v + w)≧3, and the amount (x + y + z) ranges from 0 to a value sufficient to provide up to 20 mol% of siloxane units in the molecule, and the amount (t + u + v + w)≧3]. Alternatively, (t + u + v + w) can have a value of 3 or more, or 3 to 2,000, or 3 to 1,000, or 3 to 500, or 3 to 300, or 3 to 200. In this unit formula, each R is independently selected from the group consisting of alkyl and halogenated alkyl groups. Alternatively, when the polyorganosiloxane is linear or cyclic, the amount (x + y + z)=0.

[0009] Examples of the alkyl group suitable for R include methyl, ethyl, propyl (including n-propyl and / or isopropyl), butyl (including n-butyl, t-butyl, sec-butyl, and / or isobutyl), pentyl (including cyclopentyl, n-pentyl, and branched isomer species having 5 carbon atoms), hexyl (including cyclohexyl, n-hexyl, and branched isomer species having 6 carbon atoms), heptyl (including cycloheptyl, n-heptyl, and branched isomer species having 7 carbon atoms), octyl (including cyclooctyl, n-octyl, and branched isomer species having 8 carbon atoms), nonyl (including cyclononyl, n-nonyl, and branched isomer species having 9 carbon atoms), and decyl (including cyclodecyl, n-decyl, and branched isomer species having 10 carbon atoms). The halogenated alkyl group suitable for R is an alkyl group in which one or more hydrogen atoms bonded to a carbon atom are formally substituted with a halogen atom (such as those described above). Examples of the halogenated alkyl group include fluorinated alkyl groups, such as trifluoromethyl (CF3), fluoromethyl, trifluoroethyl, 2-fluoropropyl, 3,3,3-trifluoropropyl, 4,4,4-trifluorobutyl, 4,4,4,3,3-pentafluorobutyl, 5,5,5,4,4,3,3-heptafluoropentyl, 6,6,6,5,5,4,4,3,3-nonafluorohexyl, 8,8,8,7,7-pentafluorooctyl, 2,2-difluorocyclopropyl, 2,3-difluorocyclobutyl, 3,4-difluorocyclohexyl, and 3,4-difluoro-5-methylcycloheptyl, and chlorinated alkyl groups, such as chloromethyl, 3-chloropropyl, 2,2-dichlorocyclopropyl, and 2,3-dichlorocyclopentyl. Alternatively, each R may be selected from methyl, ethyl, propyl or butyl, or from methyl or ethyl, or each R 2 may be a methyl group.

[0010] In the above formula, each R' is an alkenyl group independently selected. The alkenyl group suitable for R' may be selected from the group consisting of vinyl, allyl, and hexenyl, or vinyl and hexenyl, or vinyl.

[0011] When the polyorganosiloxane has both (R2SiO 2 / 2 ) units and (RR’SiO 2 / 2 ) units, starting materials A) and B) can be the same molecule. Alternatively, starting materials A) and B) can be different molecules.

[0012] For example, starting material A) is A1) a cyclic polydiorganosiloxane of the unit formula (R2SiO 2 / 2 ) c [wherein 3 ≦ c ≦ 12], A2) a unit formula (R3SiO 1 / 2 ) a (R2R’SiO 1 / 2 ) d (R2SiO 2 / 2 ) b[wherein, the amount (a + d) = 2, and 3 ≤ b ≤ 200], and may be selected from the group consisting of combinations of both A3), A1), and A2). In the unit formulas of A1) and A2), R and R' are as described above. Alternatively, in starting material A1), the subscript c may be 3 or more, or 3 ≤ c ≤ 9, or 3 ≤ c ≤ 6, or 4 ≤ c ≤ 6. Alternatively, in starting material A2), the subscript d may be 0. Cyclic polydiorganosiloxanes suitable for use as starting material A1) are known in the art and are commercially available. For example, dimethylcyclosiloxanes exemplified by octaorganocyclotetrasiloxanes such as 2,2,4,4,6,6,8,8,-octamethylcyclotetrasiloxane, decaorganocyclopentasiloxanes such as 2,2,4,4,6,6,8,8,-decamethylcyclopentasiloxane; and dodecaorganocyclohexasiloxanes such as 2,2,4,4,6,6,8,8,10,10-dodecamethylcyclohexasiloxane are known in the art and are commercially available from various suppliers such as Dow Silicones Corporation (Midland, Michigan, USA), Gelest, Inc. (Morrisville, Pennsylvania, USA), and Sigma-Aldrich, Inc. (St. Louis, Missouri, USA). Suitable linear polyorganosiloxanes suitable for use as starting material A2) include trimethylsiloxy-terminated polydimethylsiloxane, which are also known in the art and are commercially available from the same suppliers as above. For example, trimethylsiloxy-terminated polydimethylsiloxane having viscosities of 5 cSt, 10 cSt, 50 cSt, 500 cSt, and 1,000 cSt are commercially available from Dow Silicones Corporation (Midland, Michigan, USA). The viscosity can be measured at 25 °C and 0.1 - 50 RPM with a Brookfield DV-III cone and plate viscometer equipped with a #CP-52 spindle.Those skilled in the art can recognize that as the viscosity increases, the rotational speed decreases, and can select an appropriate rotational speed when measuring the viscosity using this test method. Alternatively, suitable dimethylvinyl-siloxy terminated polydimethylsiloxanes can be used as starting material A2), which are also known in the art and are commercially available under the trade names: DMS-V00, DMS-V05, DMS-V21, and DMS-V31 from various vendors including Gelest, Inc. Alternatively, starting material A) may not contain silicon-bonded alkenyl atoms.

[0013] Starting material B) is alkenyl-functional and is selected from the group consisting of B1) cyclic polyorganosiloxanes of the unit formula (RR’SiO 2 / 2 ) c [where 3 ≤ c ≤ 12], B2) linear polyorganosiloxanes of the unit formula (R3SiO 1 / 2 ) a (R2R’SiO 1 / 2 ) d (RR’SiO 2 / 2 ) e [where the amounts (a + d) = 2 and 3 ≤ e ≤ 200], and B3) combinations of both B1) and B2). In the unit formulas of B1) and B2), R and R’ are as described above. Alternatively, in the unit formula of B1), the subscript c can be 3 or more, or 3 ≤ c ≤ 9, or 3 ≤ c ≤ 6, or 4 ≤ c ≤ 6. Alternatively, in the unit formula of B2), the subscript d can be 0.

[0014] Cyclic polyorganosiloxanes suitable as starting material B1) are known in the art and are commercially available. Examples of cyclic alkenyl-functionalized polydiorganosiloxanes include 2,4,6-trimethyl-2,4,6-trivinyl-cyclotrisiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane, 2,4,6,8,10-pentamethyl-2,4,6,8,10-pentavinyl-cyclopentasiloxane, and 2,4,6,8,10,12-hexamethyl-2,4,6,8,10,12-hexavinyl-cyclohexasiloxane. These cyclic alkenyl-functionalized polydiorganosiloxanes are known in the art and are commercially available from, for example, Sigma-Aldrich (St. Louis, Missouri, USA), Milliken (Spartanburg, South Carolina, USA), and other vendors.

[0015] The starting material (B2) may include alkenyl-functionalized polydiorganosiloxanes such as i) bis-dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane), ii) bis-dimethylvinylsiloxy-terminated polymethylvinylsiloxane, iii) bis-trimethylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane), iv) bis-trimethylsiloxy-terminated polymethylvinylsiloxane, v) bis-dimethylhexenylsiloxy-terminated poly(dimethylsiloxane / methylhexenylsiloxane), vi) bis-dimethylhexenylsiloxy-terminated polymethylhexenylsiloxane, vii) bis-trimethylsiloxy-terminated poly(dimethylsiloxane / methylhexenylsiloxane), viii) bis-trimethylsiloxy-terminated polymethylhexenylsiloxane, ix) bis-dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylhexenylsiloxane), and x) combinations of two or more thereof.

[0016] The above-described method for preparing the linear alkenyl-functional polydiorganosiloxane for the starting material (B2), for example, hydrolysis and condensation of the corresponding organohalosilane and oligomer, or equilibration of a cyclic polydiorganosiloxane and a hydroxy-functional polydiorganosiloxane, is known in the art. See, for example, U.S. Patent Nos. 4,772,515 and 5,317,072, which disclose preparing linear polydiorganosiloxanes having alkenyl groups. Examples of linear polydiorganosiloxanes having alkenyl groups are commercially available, for example, from Gelest Inc. (Morrisville, Pennsylvania, USA) under the trade names VDT-123, VDT-127, VDT-131, VDT-431, VDT-731, and VDV-0131.

[0017] Starting material C) is a base catalyst suitable for catalyzing the equilibration reaction in the methods described herein. The catalyst may be homogeneous or heterogeneous. Suitable catalysts include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, tetrabutylphosphonium hydroxide, tetramethylammonium hydroxide, phosphazene bases, and silanolates such as potassium trimethylsilanolate and tetramethylammonium silanolate. Catalysts suitable for use as starting material C) are known in the art and are, for example, the base catalysts disclosed in U.S. Patent Nos. 3,183,209, 4,772,515, or 6,448,196, and are commercially available from various vendors such as Millipore Sigma (St. Louis, Missouri, USA).

[0018] The amount of starting material C) which is a catalyst is an amount sufficient to catalyze the equilibration reaction. The exact amount of C) catalyst varies depending on various factors such as whether the catalyst is homogeneous or heterogeneous and whether the method is carried out batchwise or continuously, but the amount of catalyst can be more than 0 to 10% by weight, or more than 0 to 5% by weight, or more than 0 to 0.1% by weight based on the total weight of starting materials A), B), C), and D) used in the method. Alternatively, the amount of heterogeneous catalyst used in a batch process can be more than 0 to 5% by weight, or more than 0 to 2% by weight, or 0.5% to 5% by weight, or 1% to 5% by weight, or 1% to 2% by weight based on the total weight of starting materials A), B), C), and D) used in step 1) of the method. Alternatively, when the method is carried out batchwise using a homogeneous catalyst, the amount of catalyst can be more than 0 to 1%. Alternatively, when the method is carried out continuously, the amount of catalyst may be different. For example, a heterogeneous catalyst can be used in a packed bed for a continuous process and the amount of catalyst varies depending on the size of the reactor.

[0019] The starting materials used in the method may not contain water. Without being bound by theory, water is thought to be able to inhibit the C) base catalyst. "Free of water" means that the starting material does not contain water, or contains an undetectable amount of water, or contains an amount of water insufficient to inhibit the C) base catalyst. The starting materials used in the method may optionally further comprise one or more additional starting materials. For example, the additional starting material may be selected from the group consisting of D) end capping agent, E) quenching agent, or both.

[0020] The end capping agent is different from starting materials A) and B) and has the unit formula (R3SiO 1 / 2 ) e (R2R’SiO 1 / 2 ) f (R2SiO 2 / 2 ) g (RR’SiO 2 / 2 ) h[wherein, R and R’ are as described above, subscript e is 0, 1, or 2, subscript f is 0, 1, or 2, the quantity (e + f) = 2, subscript g ≥ 0, subscript h ≥ 0, and 0 ≤ (g + h) ≤ 3] may be included. Alternatively, the quantity (g + h) may be 0 to 2, or 0 to 1. End-capping agents are known in the art and are commercially available. Examples of end-capping agents include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,1,1,3,3-pentamethyl-3-vinyl-disiloxane, 1,1,1,3,5,5,5-heptamethyl-3-vinyl-trisiloxane (all of which are commercially available, for example, from Gelest, Inc. (Morrisville, Pennsylvania, USA) or Sigma-Aldrich (St. Louis, Missouri, USA)).

[0021] The end-capping agent is optional. However, the end-capping agent may be used, for example, when the cyclic starting materials A1) and B1) are used in the method. The end-capping agent may be used in an amount of 0 to 44.5 wt%, or 0 to 40 wt%, or 0 to 30 wt%, or 0 to 25 wt% based on the total weight of starting materials A), B), C), and D). The balance of the starting materials used in the method may be starting materials A) and B). Alternatively, starting materials A) and B) may constitute 45.5 wt% to less than 100 wt%, or 50 wt% to less than 100 wt%, or 60 wt% to less than 100 wt%, or 75 wt% to less than 100 wt% based on the total weight of starting materials A), B), C), and D) used in the method.

[0022] Steps 1) and 2) of this method can be carried out by any convenient means using conventional equipment. For example, the starting materials can be combined in a jacketed vessel equipped with a stirrer. The starting materials can be added to the vessel in any order. Steps 1) and 2) can be carried out continuously or simultaneously. Step 2) can be carried out by mixing with a stirrer while controlling the temperature in the vessel to a temperature of 100°C to 160°C, or 140°C to 150°C, when the equilibration reaction occurs.

[0023] The equilibration reaction described herein is represented by the following exemplary reaction scheme:

[0024] [Chemical formula] [Wherein, R and R’ are as described above, subscript m is from 1 to 10, subscript n is from 1 to 10, subscript o is from 0 to 3, the amount (p + q) ≥ 3, mainly from 3 to 9, and the amount (r + s) = 10 to 1,000]. Alternatively, subscript s can be from 10 to 500, or from 30 to 250, and subscript r can be from 3 to 70. Alternatively, each R can be methyl, subscript m can have an average value of 2, subscript n can have an average value of 2, and subscript o can be 0. In the above reaction scheme, it includes ring-opening of cyclic siloxane and end-capping with the end-capping agent shown above, and the equilibration of the bond from one molecule to another molecule.

[0025] [Chemical formula] The equilibration of the bond is included in the reaction. It may be desirable to produce a fully equilibrated product.

[0026] Using the above reaction scheme, in step 2), a polyorganosiloxane copolymer product and a mixed cyclic by-product are formed. The copolymer has the formula (R2SiO 2 / 2 ) of D units and the formula (RR’SiO 2 / 2 ) of DVi contains units. Although not bound by theory, during step 2), once formed, the copolymer is thought to have a block-like distribution of difunctional units, i.e., blocks of D Vi units and blocks of D units. Over time as the equilibration reaction proceeds, the positions of the D units and D Vi units change to more randomly chained in the copolymer backbone. Raman spectroscopy can be used to determine the characteristic Raman bands (peaks on the spectrum) corresponding to the coupling D Vi units and the decoupling D Vi units. Coupling refers to a D Vi unit adjacent to another D Vi unit in the copolymer backbone. Decoupling refers to a D Vi unit not adjacent to another D Vi unit in the copolymer backbone.

[0027] The inventors have found that Raman spectroscopy can be used to monitor the reaction mixture in real time in step 3) of the above method. Further, Raman spectroscopy can be used to monitor the reaction mixture in situ. The inventors have surprisingly found that Raman spectroscopy can detect changes in the chains (e.g., block-like chains or random chains) of D units and D Vi units in the polyorganosiloxane copolymer backbone. Further, the Raman spectroscopy described herein can be used for copolymers in which the D:D Vi ratio is at least 1:1, or at least 1.5:1, or at least 2:1. At the same time, the D:D Vi ratio of the copolymer can be up to 30:1, or up to 15:1, or up to 10:1, or up to 5:1, or up to 3:1. Alternatively, the Raman spectroscopy described herein can be used for copolymers in which the D:D Vi ratio is from 1:1 to 30:1, or from 1:1.5 to 1:2.5, or from 1:2 to 1:3. Alternatively, the Raman spectroscopy described herein can be used for copolymers in which the D:D ViIt can be used for copolymers in which the ratio is from 100:1 to 1:100, or from 75:1 to 1:75, or from 50:1 to 1:50, or from 30:1 to 1:30, or from 5:1 to 1:5, or from 3:1 to 1:3, or from 2.5:1 to 1:2.5, or from 2:1 to 1:2, or from 1.5:1 to 1:1.5.

[0028] The intensity of characteristic Raman bands (e.g., peak height and / or peak area on the spectrum measured by Raman spectroscopy) can be measured at time intervals as the equilibration reaction progresses. The peak area and peak height of the decoupling Si-R' Raman band increase with the increase in reaction time, while the peak area and peak height of the coupling Si-R' Raman band decrease with the increase in reaction time. U.S. Patent Application Publication No. 2004 / 0198927 discloses an apparatus for measuring the intensity of characteristic Raman bands (to obtain peak height and peak area) using Raman spectroscopy. Using these Raman characteristics, the target value at the reaction termination time can be set to optimize the properties of the polyorganosiloxane copolymer and / or optimize the reaction batch time. The target value can be set based on the decoupling Si-R' peak area, decoupling Si-R' peak height, coupling Si-R' peak area, and / or coupling Si-R' peak height. The reaction can be controlled by stopping the reaction when the value of any one or more of these characteristics reaches the target value. A person skilled in the art can set the target value for each of these parameters to optimize the application performance while minimizing the batch time. It is also possible to set the target value based on the change rate of any of these parameters. For example, as the reaction progresses, the decoupling Si-R' peak area increases until it reaches the maximum value and then levels off, as shown in FIGS. 1 and 3 below, for example.

[0029] The change rate of the intensity of each characteristic Raman band can be calculated over each time interval. When the change rate approaches zero, this indicates that the copolymer is fully equilibrated (D units and DVi The units are randomly distributed). Therefore, when a random copolymer is desired, the target value can be set, for example, to a value of 0% to 10% of the maximum absolute value change rate over a selected time interval, such as the 15-minute average value measurable during the equilibration reaction to stop the reaction in step 4). Alternatively, as described and illustrated below in the examples of this specification, for any of the characteristics of the decoupling Si-R' peak area, decoupling Si-R' peak height, coupling Si-R' peak area, or coupling Si-R' peak height, the target value can be set to stop the reaction when the change rate reaches a predetermined value. Alternatively, the target value can be set to stop the reaction when the decoupling Si-R' peak height or decoupling Si-R' peak area reaches its maximum value, or 90% to 100% of its maximum value. Alternatively, the target value can be set to stop the reaction when the coupling Si-R' peak height or coupling Si-R' peak area reaches its minimum value, or 0% to 10% of its minimum value. One or more of the features described in this specification can be used for setting the target value and / or for the determination when the target value is reached. Alternatively, mathematical transformation to peak height, peak area, or change rate data can be used to smooth the resulting data. This includes, but is not limited to, averaging over multiple instrument readings or fitting the data to a mathematical equation (such as exponential decay or logistic function) of the data. Chemometric analyses such as classical least square (CLS), partial least square (PLS), and principal component regression (PCR) can also be used instead of the univariate analysis described above for setting the target value.

[0030] The termination of the reaction in step 4) can be carried out by any convenient means, such as cooling and / or filtering to remove the catalyst (when a heterogeneous catalyst is used) or neutralizing with a quenching agent to form a salt (when a homogeneous catalyst is used), and then removing it by filtration in a batch or continuous mode. The quenching agent is known in the art and is exemplified by acetic acid, silyl phosphate, silyl phosphonate, and carbon dioxide.

[0031] The method described herein may optionally further include one or more additional steps. For example, the method may further include step 5): recovering the polyorganosiloxane copolymer. During the equilibration reaction, by-products (such as the mixed rings described above in the exemplary reaction scheme) may be formed, and / or unreacted starting materials A) and / or B) may be present in the reaction mixture. The recovery can be carried out by any convenient means, such as stripping and / or distillation to remove unreacted starting materials and / or by-products from the polyorganosiloxane copolymer.

[0032] The method may optionally further include step 6): repeating steps 1) to 4) (and optionally 5) while reusing the catalyst in step 1) (when a heterogeneous catalyst is used).

[0033] The method described herein has the unit formula: (R3SiO 1 / 2 ) tt (R2R’SiO 1 / 2 ) uu (R2SiO 2 / 2 ) vv (RR’SiO 2 / 2 ) ww (RSiO 3 / 2 ) xx (R’SiO 3 / 2 ) yy (SiO 4 / 2 ) zz[wherein the subscripted letters tt, uu, vv, ww, xx, yy, and zz represent the average values of the respective units in the copolymer, with subscripted letters tt ≥ 0, uu ≥ 0, vv ≥ 1, ww ≥ 1, xx ≥ 0, yy ≥ 0, zz ≥ 0, provided that the amount (vv + ww) ≥ 3, and the amount (xx + yy + zz) ranges from 0 to a value sufficient to provide up to 20 mol% of siloxane units in the copolymer molecules, and the amount (tt + uu + vv + ww) ≥ 3]. A polyorganosiloxane copolymer can be produced. Alternatively, the amount (tt + uu + vv + ww) can be 5 or more. Alternatively, (tt + uu + vv + ww) can have a value of 5 to 2,000, or 5 to 1,000, or 10 to 500, or 25 to 300, or 50 to 200. This copolymer has at least one property, for example, molecular weight, (R2SiO 2 / 2 ) and (RR’SiO 2 / 2 ) unit distribution, and the molar ratio (D:D 2 / 2 ) of the units of formula (R2SiO 2 / 2 ) and the units of formula (RR’SiO Vi ) is different from the starting materials (A) and (B). The copolymer also contains both D units and D Vi units. The D:D Vi ratio can be 100:1 to 1:100, or 75:1 to 1:75, or 50:1 to 1:50, or 30:1 to 1:30, or 5:1 to 1:5, or 3:1 to 1:3, or 2.5:1 to 1:2.5, or 2:1 to 1:2, or 1.5:1 to 1:1.5, or 1:1 to 30:1, or 1:1.5 to 1:2.5, or 1:2 to 1:3. Alternatively, the copolymer produced by the method described herein can be linear, and when subscripted letters xx = 0, yy = 0, and zz = 0, the copolymer has the unit formula: (R3SiO 1 / 2 ) tt (R2R’SiO 1 / 2 ) uu (R2SiO 2 / 2 ) vv (RR’SiO 2 / 2 ) wwmay have, subscript tt is 0, 1, or 2, subscript uu is 0, 1, or 2, the quantity (tt + uu) = 2, subscript vv > 1, subscript ww > 1, and subscript vv and ww have values such that the D:D Vi ratio is as described above.

Example

[0034] The following examples are intended to illustrate the present invention to those skilled in the art and should not be construed as limiting the scope of the present invention claimed. The reactants and other starting materials used in the examples are shown in Table 1 below. When used in the following examples, "calculated value" refers to the D Vi and DP of the copolymer calculated based on the amounts of each starting material used.

[0035]

Table 1

[0036] In Table 1, DSC refers to Dow Silicones Corporation (Midland, Michigan, USA), and TDCC refers to The Dow Chemical Company (Midland, Michigan, USA).

[0037] Reference Example A - Raman Spectroscopy Technique The progress of the reaction was monitored by Raman spectroscopy using the following apparatus and settings: BWTek i-Raman Pro, probe head: liquid immersion optical system: 0.5 inch O.D. × 10 inch L Hastelloy C-276 shaft and gold-sealed sapphire lens from Kaiser Optical Systems, Inc. and 785 nm excitation. 150 cm -1Raman cut-off at. Laser fiber 105μm core FC / PC termination. Raman fiber 300μm core FC / PC termination. Fiber cable length 1.5m. Spectra were collected with two average values at an exposure time of 10 seconds. The spectra were then processed to determine the peak area trend lines for the coupling and decoupling - OSiMeVi - portions.

[0038] Reference Example B - Apparatus for Copolymerization A 500 mL two - component batch reactor was used to prepare poly(dimethyl / methylvinyl)siloxane copolymer. The upper (flange) part of the reactor had three 29 / 42 ports in a straight line, two 1 / 4 - inch Ace threaded ports and a 3 / 8 - inch Ace threaded port on one side, and a 24 / 40 port on the other side. The central 29 / 42 port had a stirring shaft connected to an overhead stirrer equipped with a three - blade glass impeller. One 29 / 42 port had a Dean Stark trap connected to a condenser, and this condenser was connected to a cooler flowing Syltherm XLT at 10°C. The condenser was connected to a nitrogen inlet via a T - tube, whereby the reaction headspace could be purged or positioned under a nitrogen pad. The nitrogen line was vented through a mineral oil bubbler. The other 29 / 42 included a sampling port with a Teflon tube extending into the reactor. A 3 / 8 - inch Ace thread was used to insert a Raman probe for in - situ analysis, and for the 1 / 4 - inch port, one side included a glass thermowell and a thermocouple, and the other side included a nitrogen inlet. The 24 / 40 neck included a Raman probe attached through a rubber septum. The lower reactor part was sealed with a Teflon - coated O - ring coated with Krytox (trademark). It was clamped in place using a compression clamp and fixed with an insulating C - clamp. A heating mantle with a thermocouple was positioned over the lower part of the reactor and fixed in place with a ring clamp and a lab jack.

[0039] Reference Example C - Copolymerization Procedure The copolymerization of cyclic reactants was carried out according to the following reaction scheme.

[0040]

Chemical Formula

[0041] A 500 mL glass reactor equipped with an overhead stirrer with a glass impeller, a thermocouple, an 1 / 8-inch Teflon sampling tube with a three-way valve, a Dean-Stark trap with a water-cooled reflux condenser, a nitrogen sweep, and a Raman spectrometer probe was used. D4, V4, and the end-capping agent M were charged into the flask. Vi D 7.2 M Vi and the nitrogen sweep was stopped. Raman spectroscopy was started and spectra were acquired every 20 seconds. The reaction mixture was stirred at 250 rpm and heated to 160 °C using a heating mantle equipped with a temperature controller. The catalyst in the amounts shown in Table 2 below was added to the reaction mixture, and about 2 mL of D4 was added thereto. The reaction was stopped after 3 hours and quenched with 5.9 g of a neutralizing agent (2.5 wt% in D4).

[0042]

Table 2

[0043] In Table 2, W represents examples and C represents comparative examples. Figure 1 shows the integrated peak area as a function of time for the decoupled -OSiMeVi- moieties of three different samples having different -OSiMeVi- contents with respect to weight percent. Sample C1 was the homopolymerization of V4 (shown by the gray x in Figure 1), which showed no randomization because all pendant groups were identical. This was at 750 cm -1It is clear that the peak area at [conditions] remains constant throughout the test. Two other tests were carried out using 90:10 D4:V4 (sample W4, circle) and 50:50 D4:V4 (samples W1 - W3, square). Increasing the V4 content allows for more randomization along the main chain and thus greater normalized Raman intensity at the end of the run. The rate at which randomization reached equilibrium was significantly different for both the 90:10 D4:V4 and 50:50 D4:V4 samples.

[0044] Reference Example D - Copolymerization with Linear Reactants Copolymerization with linear reactants was carried out according to the following reaction scheme.

[0045]

Chemical Structure

[0046] A 500 mL glass reactor equipped with an overhead stirrer with a glass impeller, a thermocouple, a 1 / 8 inch Teflon sampling tube with a three-way valve, a Dean - Stark trap with a water - cooled reflux condenser, a nitrogen sweep, and a Raman spectrometer probe was used. The flask was charged with 29.4 g (21.3 mmol) of MeVi homopolymer (stripped of cyclic compounds before use) and 168.8 g of PDMS (243 mmol), and the nitrogen sweep was stopped. Raman spectroscopy was initiated and spectra were acquired every 20 seconds. The reaction mixture was stirred at 250 rpm and heated to 160 °C using a heating mantle equipped with a temperature controller. To the reaction mixture, 1.8 g (36 ppm K+) of Catalyst 2 (12 wt%) was added, and approximately 2 mL of toluene was added thereto. After 4 hours, the reaction was stopped and quenched with 2.16 g of 4 - 6085 neutralizer (2.5 wt% in D4). The data in Table 3 below show that this method can be carried out using linear reactants.

[0047]

Table 3

[0048] Although not bound by theory, it is believed that an advantage of the present invention is that using this method allows selection of the desired degree of randomization of D units and D units in the main chain of the polyorganosiloxane copolymer produced by this method while minimizing batch time. For example, a high peak area target value, such as a maximum 15-minute average absolute rate of change of ≤10%, can be selected to obtain a highly randomized copolymer. Alternatively, for example, if a copolymer having a more blocky structure is acceptable, the target value can be set at a lower decoupling SiR' peak area (or other suitable target value) to minimize the batch time for producing the copolymer. Vi Although not bound by theory, it is believed that an advantage of the present invention is that using this method allows selection of the desired degree of randomization of D units and D units in the main chain of the polyorganosiloxane copolymer produced by this method while minimizing batch time. For example, a high peak area target value, such as a maximum 15-minute average absolute rate of change of ≤10%, can be selected to obtain a highly randomized copolymer. Alternatively, for example, if a copolymer having a more blocky structure is acceptable, the target value can be set at a lower decoupling SiR' peak area (or other suitable target value) to minimize the batch time for producing the copolymer.

Industrial Applicability

[0049] Polyorganosiloxane copolymers are useful intermediates in the synthesis of various organofunctional siloxane products. Specifically, D units of the formula (R2SiO 2 / 2 ) and D units of the formula (RR'SiO 2 / 2 ) of such copolymers are useful as crosslinkable base polymers in various curing systems, such as free radical and / or hydrosilylation reaction curable products. Vi units of such copolymers are useful as crosslinkable base polymers in various curing systems, such as free radical and / or hydrosilylation reaction curable products.

[0050] Although not bound by theory, it is believed that the distribution of alkenyl functional groups along the polysiloxane main chain can affect both the physical and chemical properties of the resulting polyorganosiloxane copolymer. For example, a blocky structure can have different reactivity than a random structure. The degree of randomness can affect physical properties such as elongation, tensile strength, or hardness in downstream applications. It is desirable to achieve a consistent chain distribution along the polysiloxane main chain to promote consistent performance during equilibration and polymerization reactions.

[0051] The polyorganosiloxane produced by the method described herein has a blocky main chain structure (e.g., DDDDD Vi DVi D Vi D Vi DDD) [wherein a plurality of D units are grouped together and the plurality of D Vi units are grouped together as a "block"]. However, without being bound by theory, the inventors believe that a more random backbone structure (e.g., DDDDD Vi DDDD Vi DD Vi DDD Vi DDDDDDDD Vi ) [wherein the D units and D Vi units are more randomly distributed along the backbone] may be desirable for use in certain applications, such as curable silicone compositions, for example, hydrosilylation reaction curable silicone elastomer compositions. Further, the polyorganosiloxanes produced by the methods described herein may reach their target molecular weight at a point (possibly quite early) that is different from when the distribution of D units and D Vi units in the backbone is randomly distributed. As a result, the degree of "randomness" of the siloxane backbone structure may vary from batch to batch and may affect physical properties and performance. Also, the degree of randomness may affect the performance of the copolymer. The methods described herein can be used both to minimize batch time and to maximize the randomization of the polyorganosiloxane copolymer by appropriately selecting a target value for stopping the reaction in the methods described herein.

[0052] Further, without being bound by theory, the Raman spectroscopy methods described herein can alternatively be used for the production of other polyorganosiloxane copolymers having, instead of the moiety of the formula (RR’SiO 2 / 2 ) [wherein R and R’ are as defined above], a moiety of the formula (RR’’SiO 2 / 2 ) [wherein R’’ is an aryl group such as phenyl].

[0053] Definition and Use of Terms All amounts, ratios, and percentages are by weight unless otherwise indicated. The amounts of all starting materials in the composition total 100 weight %. The abstract and summary of the invention are incorporated herein by reference. The articles "a," "an," and "the" each refer to one or more unless otherwise specifically indicated by the context of the specification. The singular form includes the plural form unless otherwise stated. The term "comprising" and its derivatives, such as "comprise" and "comprises," mean "including," "include," "consist(ing) essentially of," and "consist(ing) of," and are used herein in their broadest sense to mean including. The use of "for example," "e.g.," "such as," and "including" for listing examples is not limited to only the examples listed. Thus, "for example" or "such as" means "for example, but not limited to" or "such as, but not limited to," and includes other similar or equivalent examples.

[0054] "Decoupling D Vi " and "decoupling (RR’SiO 2 / 2 )" refer to units of the formula (RR’SiO 2 / 2 ) in the siloxane backbone of a copolymer that are not adjacent to other (RR’SiO 2 / 2 ) units. For example, at the site of -(R2SiO 2 / 2 )-(RR’SiO 2 / 2 )-(R2SiO 2 / 2 )-, the (RR’SiO 2 / 2 ) unit is a decoupling (RR’SiO 2 / 2) That is. Except for the completely alternating copolymer main chains that are not preferred in the equilibration reaction described in this specification, the more decoupling (RR’SiO 2 / 2 ) there is in the copolymer main chain, the higher the degree of randomness of the copolymer.

[0055] "Coupling D Vi " and the term "coupling (RR’SiO 2 / 2 )" refer to units of the formula (RR’SiO 2 / 2 ) adjacent to other (RR’SiO 2 / 2 ) units. For example, in the moiety -(RR’SiO 2 / 2 )-(RR’SiO 2 / 2 )-(RR’SiO 2 / 2 )-, the (RR’SiO 2 / 2 ) units are coupled. The more coupling SiR’ there is in the copolymer, the more block-like its properties.

[0056] It should be understood that the appended claims are not limited to the specific compounds, compositions, or methods described in the embodiments for carrying out the invention, and these may vary among the specific embodiments that fall within the scope of the appended claims. With respect to any Markush group relied upon herein to describe a particular feature or aspect of the various embodiments, different, special, and / or unexpected results may be obtained from each element of each Markush group independent of all other Markush elements. Each element of a Markush group may be relied upon individually and / or in combination and provides sufficient support for a specific embodiment within the scope of the appended claims.

[0057] When describing various embodiments of the present invention, any ranges and sub-ranges relied upon are, independently and inclusively, within the scope of the appended claims, and are to be understood to describe and contemplate the full range including such values therein even if no integer and / or fractional values are specified herein. One skilled in the art will readily recognize that the recited ranges and sub-ranges fully describe and enable various embodiments of the present invention, and that such ranges and sub-ranges can be further depicted in related bisectors, trisectors, quadrisectors, quintisectors, etc. By way of mere example, the range "20 to 110" can be further detailed into a lower third, namely 20 to 49, a middle third, namely 50 to 79, and an upper third, namely 80 to 110, which are individually and collectively within the scope of the appended claims, and specific embodiments within the scope of the appended claims can individually and / or collectively rely upon them and provide adequate support therefor. Additionally, with respect to words defining or modifying a range, such as "at least", "more than", "less than", "below", etc., such words are to be understood to include sub-ranges and / or upper or lower limits. Further, individual numbers within the disclosed ranges can be relied upon by and provide adequate support for specific embodiments within the scope of the appended claims.

[0058] The abbreviations used herein are defined in Table 4.

[0059]

Table 4

Claims

1. A method for preparing a polyorganosiloxane copolymer, said method comprising: １） A) A source of siloxane units of the formula (R ２ SiO ２／２ ) B) formula (RR'SiO ２／２ ) a source of siloxane units of the formula: [[wherein each R is independently selected from the group consisting of alkyl groups and halogenated alkyl groups, and R′ represents an alkenyl group]], and C) a base catalyst, combining the starting materials containing them to form a mixture; 2) stirring said mixture at a temperature sufficient to form a reaction mixture containing said copolymer via an equilibration reaction; 3) Using Raman spectroscopy, monitoring a spectral region containing characteristic Raman bands corresponding to one or both of the concentration of decoupling (RR'SiO ２／２ ) units and the concentration of coupling (RR'SiO ２／２ ) units in the reaction mixture; 4) stopping said equilibration reaction when a target value associated with said characteristic Raman band is reached. A method comprising the steps of:

2. Said target value is i) the height or area of a characteristic Raman band, ii) the rate of change of the height or area of said characteristic Raman band, iii) a mathematically transformed value of one or both of i) and ii), and iv) a chemometric analysis value of the spectral region containing said characteristic Raman band, selected from the group consisting of: The method according to claim 1.

3. Said target value is the rate of change of the height of said characteristic Raman band or the rate of change of the area of said characteristic Raman band, said rate of change having a value from 0% to 10% of its maximum absolute value measurable during said equilibration reaction. The method according to claim 2.

4. Decoupling (RR'SiO ２／２ ) The method according to claim 2 or 3, wherein the characteristic Raman band area is used.

5. Starting materials A) and B) are of the unit formula (R ３ SiO １／２ ), ｔ (R ２ R'SiO １／２ ), ｕ (R ２ SiO ２／２ ), ｖ (RR'SiO ２／２ ), ｗ (RSiO ３／２ ), ｘ (R'SiO ３／２ ), ｙ (SiO ４／２ ), ｚ [where the subscripts t, u, v, w, x, y, and z represent the amounts of each unit, t ≥ 0, u ≥ 0, v ≥ 1, w ≥ 1, x ≥ 0, y ≥ 0, z ≥ 0, provided that the amount (v + w) is from 3 to 300, the amount (x + y + z) is from 0 to a value sufficient to provide up to 20 mol% of the units in the molecule, and the amount (t + u + v + w) ≥ 3]. The method according to any one of claims 1 to 4.

6. The starting material A) is A1) Unit formula (R ２ SiO ２／２ ) ｃ [wherein, 3 ≦ c is ≦ 12] and contains a cyclic polydiorganosiloxane A2) Unit formula (R ３ SiO １／２ ) ａ (R ２ R'SiO １／２ ) ｄ (R ２ SiO ２／２ ) ｂ [wherein, 0 ≦ a ≦ 2, 0 ≦ d ≦ 2, the amount (a + d) = 2, and 3 ≦ b ≦ 200], and a linear polydiorganosiloxane containing A3) selected from the group consisting of combinations of both A1) and A2). The method according to any one of claims 1 to 5.

7. The starting material B) is B1) Unit formula (RR'SiO ２／２ ) ｃ [wherein, 3 ≤ c ≤ 12] cyclic alkenyl-functional polydiorganosiloxane, B2) Unit formula (R ３ SiO １／２ ) ａ (R ２ R'SiO １／２ ) ｄ (RR'SiO ２／２ ) ｅ [wherein, 0 ≦ a ≦ 2, 0 ≦ d ≦ 2, the quantity (a + d) = 2, and 3 ≦ e ≦ 200], and a linear alkenyl-functional polydiorganosiloxane, and B3) selected from the group consisting of combinations of both B1) and B2). The method according to any one of claims 1 to 6.

8. The polydiorganosiloxane contains both starting materials A) and B) in the same molecule. The method according to any one of claims 1 to 5.

9. The method according to any one of claims 1 to 8, carried out batchwise.

10. Said catalyst is a heterogeneous catalyst. The method according to any one of claims 1 to 9.

11. The starting materials in step 1) do not contain water. The method according to any one of claims 1 to 10.

12. The starting materials in step 1) further contain D) a terminal blocking agent. The method according to any one of claims 1 to 11.

13. wherein the terminal blocking agent has a unit formula: (R ３ SiO １／２ ), ｅ (R ２ R'SiO １／２ ), ｆ (R ２ SiO ２／２ ), ｇ (RR'SiO ２／２ ), ｈ [wherein 0 ≦ e ≦ 2, 0 ≦ f ≦ 2, the quantity (e + f) = 2, the subscript g ≧ 0, the subscript h ≧ 0, 0 ≦ (g + h) ≦ 30], the method according to claim 12

14. The method according to any one of claims 1 to 13, wherein the monitoring in step 3) is carried out via real-time and in situ analysis of the reaction mixture. **Claim 15** The method according to any one of claims 1 to 14, wherein each R' is selected from the group consisting of vinyl, allyl, and hexenyl.

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