Method for producing oxypropylene group-containing glycol ether having reduced content of allyl group-containing impurities

Abstract

[Problem] To easily and cost-effectively produce an oxypropylene group-containing glycol ether that does not adversely affect polymerization reaction when used as a reaction solvent or a diluent for a polyether-polysiloxane block copolymer, wherein the content of allyl group-containing impurities in the oxypropylene group-containing glycol ether can be reduced using relatively easy and simple industrial equipment and reaction process, and hydrosilylation reaction products and the oxypropylene group-containing glycol ether can be easily separated by distillation, etc. [Solution] A method for producing an oxypropylene group-containing glycol ether, said method comprising: a step for hydrosilylating allyl group-containing impurities contained in the oxypropylene group-containing glycol ether with a silicon atom-bound hydrogen atom (Si-H)-containing compound; and, preferably, a purification step for separating the oxypropylene group-containing glycol ether by distillation, etc.

Description

Method for producing oxypropylene group-containing glycol ethers with reduced content of allyl group-containing impurities

[0001] The present invention relates to a method for producing oxypropylene group-containing glycol ethers having a reduced content of allyl group-containing impurities, and particularly to a method for producing such glycol ethers which further includes a purification step.

[0002] The process of obtaining polyoxyalkylene derivatives by reacting alkylene oxide with a hydroxyl-containing starting material using an alkali metal hydroxide such as potassium hydroxide as a catalyst has been industrially important and has been known for a long time. Patent Document 1 reports that when polyether polyols are produced by addition polymerization of propylene oxide with polyhydric alcohols, small amounts of unsaturated groups are detected in the product. Because these impurities have a high molecular weight, they cannot be removed by conventional distillation or stripping processes.

[0003] Regarding the by-production of unsaturated compounds during the ring-opening addition polymerization of propylene oxide in the presence of a strong alkaline catalyst, Patent Document 2 explains the reaction mechanism: "When a conventional catalyst such as KOH is used, a small amount of PO is continuously rearranged to form allyl alcohol, which serves as a source of new unsaturated starting material that competes with the original starting material (starter). Eventually, conditions are established such that the addition of further PO cannot increase the overall molecular weight of the polyether product."

[0004] Glycol ethers have also been produced by a similar reaction method for a long time, but because they are low molecular weight compounds, they are usually separated through a distillation process due to differences in boiling points determined by the degree of polymerization (1, 2, or 3) and supplied to the market as high-purity raw materials. Patent Document 3 disclosed a process characterized by the use of an aprotic polar solvent that can improve the conversion rate during this process.

[0005] On the other hand, it has long been known that glycol ethers are susceptible to quality deterioration due to oxidation, and indicators of this include an increase in odor, peroxide value, carbonyl value, acid value, and ultraviolet absorbance. Patent Document 4 discloses that, in order to improve these properties, NaBH４ , K.B.H. ４ , LiAlH ４ It has been disclosed that treatment with metal hydrides such as HCl (a treatment for decomposing oxidized degradation products by reduction reaction) is superior to treatment with activated carbon or water distillation. However, metal hydrides are water-inhibiting substances and are extremely reactive, making them difficult to handle and making them difficult to apply to industrial-scale production.

[0006] Patent Document 5 reported that the amount of aldehyde, peroxide value, and ultraviolet absorbance could be reduced by reacting glycol ethers with hydrogen gas in the presence of a hydrogenation catalyst. The nickel-diatomaceous earth powder catalyst used here is generally stable in air and has the advantage of being more easily applicable to industrial production than the metal hydride described in Patent Document 4. However, since the hydrogenation reaction uses highly flammable hydrogen gas, specialized equipment is required, which significantly increases processing costs and poses problems of difficulty in market adoption and limited production capacity.

[0007] Patent Document 6 discloses a method for purifying propylene glycol monoalkyl ether, which is produced by reacting propylene oxide with an alcohol in the presence of an alkali or alkaline earth metal alkoxide, by treatment with activated carbon, which is said to have reduced carbonyl impurities and UV absorbance.

[0008] Patent Document 7 discloses a method for producing a propylene glycol monoalkyl ether obtained by reacting propylene oxide with an alcohol in the presence of an alkali or alkaline earth metal alkoxide, and then treating the propylene glycol monoalkyl ether with an alkali metal borohydride (e.g., NaBH ４ ) which is said to have reduced carbonyl impurities and UV absorbance.

[0009] Patent Document 8 discloses a foam suppressor composition containing (A) a specific silicone oil compound, (B) a mixture of a "polyhydric alcohol alkyl ether having a molecular weight of 50 to 500" such as dipropylene glycol monomethyl ether and a specific side-chain polyoxyalkylene-modified silicone oil, and (C) a surfactant other than the polyoxyalkylene-modified silicone oil, in specific ratios. It also provides an example of the synthesis of the polyoxyalkylene-modified silicone oil in the presence of dipropylene glycol monomethyl ether.

[0010] Patent Document 9 discloses a composition containing a specific side-chain polyether-modified silicone and a specific glycol ether compound, a method for producing the composition, a foam stabilizer for polyurethane foam containing the composition, etc. It also shows an example in which dipropylene glycol monobutyl ether is used as both a reaction solvent and a diluent for producing the polyether-modified silicone.

[0011] Patent Document 10 discloses a composition containing (A) a non-hydrolyzable (AB) n-type polyether-modified silicone and (B) a specific glycol ether compound in which a terminal hydrogen atom is substituted with a hydrocarbon group having 1 to 8 carbon atoms and the other terminal has a secondary alcoholic hydroxyl group, a method for producing the composition, and a foam stabilizer for polyurethane foam containing the composition. It also provides an example in which the component (B) is used as both a reaction solvent and a diluent for producing the component (A). However, the document does not describe or suggest any of the new technical problems described below.

[0012] As described above, oxypropylene group-containing glycol ethers have been conventionally purified by distillation and supplied to the market as highly purified products. However, these documents do not mention or suggest that the oxypropylene group-containing glycol ethers contain allyl group-containing impurities, that the impurities are extremely difficult to remove by conventional distillation purification, or that the technical disadvantages resulting from the impurities are not recognized.

[0013] Patent Document 5 discloses a method for converting allyl groups to inactive propyl groups. However, when this method is used in an industrially large-scale production process, it directly leads to a significant increase in production costs and a decrease in production capacity. Therefore, when attempting to reduce allyl group-containing impurities, an industrially cheaper and simpler method is desired.

[0014] Japanese Patent Publication No. 42-13762 (U.S. Patent No. 3,370,056), U.S. Patent No. 5,856,369 (Patent No. 3,971,716), International Publication No. 1996 / 036582, German Patent No. 2,831,210, Japanese Patent No. 2,553,146, U.S. Patent No. 7,439,405 (Patent No. 5,859,730), U.S. Patent No. 9,187,392 (Patent No. 6,460,434), Japanese Patent No. 3,570,490 (U.S. Patent No. 6,417,258), U.S. Patent No. 11,066,534 (WO2018074257A1), U.S. Patent No. 10,717,872 (Patent No. 6,655,066)

[0015] Meanwhile, the present inventors have investigated the use of low-cost glycol ether compound raw materials in order to provide the foam stabilizer disclosed in Patent Document 10 at lower cost. As a result, they have discovered a new and previously unreported technical problem in which the molecular weight of component (A) does not reach the target due to a problem arising from the quality of the glycol ether compound (in particular, the presence of an allyl group-containing impurity that had not been recognized), resulting in a very low viscosity of the foam stabilizer.

[0016] More specifically, the present inventors previously proposed in Patent Document 10 compositions, foam stabilizers, etc. containing (AB)n-type polyether-modified silicones and specific glycol ether compounds. These compositions are expected to exhibit excellent effects as surfactants for foam control or foam stabilization in various polyurethane foam formulations, and their simple production process makes them advantageous for industrial production and mass supply. However, the present inventors discovered a new problem in obtaining these compositions: the quality of the glycol ether compound significantly affects the quality of the composition as it is produced. Specifically, inexpensive glycol ether compounds contain large amounts of allyl group-containing impurities, which cause a side reaction during the synthesis of the (AB)n-type polyether-modified silicone that caps the growing ends of the copolymer, resulting in a low viscosity of the composition after hydrosilylation.

[0017] The particularly important role of (AB) n-type polyether-modified silicone foam stabilizers is to maintain foam during polyurethane foam formation, and the conventional method for improving foam maintenance is to design a foam stabilizer formulation to obtain a high molecular weight, high viscosity product with a large n number, that is, to react the raw material polyether and polysiloxane with a C=C / SiH molar ratio close to 1.0. However, if the glycol ether compound used as the reaction solvent contains more than a certain amount of allyl group-containing impurities, it becomes difficult to achieve the target molecular weight of the copolymer. In addition, the allyl group-containing impurities become a variable factor in the reaction system, which increases the complexity of product design and quality control of the foam stabilizer.

[0018] Due to these multiple and complex problems, (AB)n-type polyether-modified silicone foam stabilizers still have issues such as insufficient market penetration despite their potential value. Therefore, the development of a method for reducing allyl group-containing impurities, particularly in oxypropylene group-containing glycol ethers, and a method for producing purified glycol ethers with reduced allyl group-containing impurities is needed to ensure a stable supply of the foam stabilizer to the market.

[0019] The present inventors have discovered that the above-mentioned problems can be solved by a method for producing oxypropylene group-containing glycol ethers, which includes a step of hydrosilylating allyl group-containing impurities contained in the oxypropylene group-containing glycol ethers with a silicon-bonded hydrogen atom (Si—H)-containing compound, and have arrived at the present invention. After the hydrosilylation reaction step, the purity of the oxypropylene group-containing glycol ethers is preferably 90% by mass or more, more preferably 95% by mass or more, and the oxypropylene group-containing glycol ethers are preferably substantially free of allyl group-containing impurities. Furthermore, it is particularly preferable that the method further includes a purification step after the hydrosilylation reaction step, in which the oxypropylene group-containing glycol ethers and the hydrosilylation reaction product are separated by means of distillation or the like.

[0020] The present inventors have also discovered that the above-mentioned problems can be solved by a method for producing a polyether-polysiloxane block copolymer composition or a polyurethane foam-forming composition, which method uses an oxypropylene group-containing glycol ether obtained by the above-mentioned production method as a reaction solvent or diluent, and have arrived at the present invention.

[0021] The present invention makes it possible to reduce allyl group-containing impurities in oxypropylene group-containing glycol ethers using equipment and a reaction process that is relatively easy and simple on an industrial scale, and to easily separate the hydrosilylation reaction product from the oxypropylene group-containing glycol ether by distillation or the like, thereby enabling the easy and low-cost production of high-purity oxypropylene group-containing glycol ethers that do not adversely affect the polymerization reaction when used as a reaction solvent or diluent for polyether-polysiloxane block copolymers such as (AB)n-type polyether-modified silicones. As a result, even relatively inexpensive, low-quality oxypropylene group-containing glycol ethers with high impurity contents can be purified and used industrially at low cost and with ease. The use of such purified raw materials mitigates the impact of the quality of the raw materials, facilitating product design, quality control, and stable and low-cost supply of surfactants and the like (particularly foam stabilizers) containing high-performance (AB)n-type polyether-modified silicones as their main components, and is expected to enable the widespread use of these products on the market.

[0022] The method for producing oxypropylene group-containing glycol ethers according to the present invention will be described in more detail below.

[0023] In the present invention, the term "oxypropylene group-containing glycol ethers" refers to oxypropylene group-containing glycol ethers in which a terminal hydrogen atom is substituted with a hydrocarbon group having 1 to 8 carbon atoms and which have an alcoholic hydroxyl group at the other terminal, in which the number of repeating oxyalkylene units having 2 to 4 carbon atoms is in the range of 1 to 3, and which contain no heteroatoms other than oxygen. Such components are useful as reaction solvents or diluents for polyether-polysiloxane block copolymers, including (AB)n-type polyether-modified silicones, as described in Patent Document 10.

[0024] In the present invention, the oxypropylene group-containing glycol ether may be one or more glycol ethers selected from propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monopropyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, and tripropylene glycol monoethyl ether. In particular, the oxypropylene group-containing glycol ether according to the present invention is preferably one or more glycol ethers selected from dipropylene glycol monobutyl ether (hereinafter sometimes abbreviated as "BDPG") and tripropylene glycol monobutyl ether (hereinafter sometimes abbreviated as "BTPG").

[0025] Oxypropylene group-containing glycol ether products available on the market vary in the number of moles of PO added, purity, water content, acid value, etc. depending on the supplier. However, as described above, these products contain allyl group-containing impurities derived from the synthesis reaction, such as propylene glycol monoallyl ether, dipropylene glycol monoallyl ether, and tripropylene glycol monoallyl ether.

[0026] These allyl-group-containing impurities have an allyl group at only one molecular end. When such allyl-group-containing impurities are present in a polymerization reaction system for a polyether-polysiloxane block copolymer, which uses a dimethylpolysiloxane raw material having silicon-bonded hydrogen atoms at both molecular chain ends and a polyether raw material having alkenyl groups at both ends, the allyl-group-containing impurities undergo an addition reaction with the silicon-bonded hydrogen atoms at the ends of the dimethylpolysiloxane, causing a side reaction that terminates the terminal reaction. This can inhibit the intended block copolymerization and significantly reduce the molecular weight and viscosity of the final copolymer.

[0027] Therefore, when the above-mentioned oxypropylene group-containing glycol ethers are used as reaction solvents or diluents for polyether-polysiloxane block copolymers, particularly when used as reaction solvents, it is necessary to minimize the amount of allyl group-containing impurities that cause side reactions, from the standpoint of the quality of the resulting copolymer and production control. However, these allyl group-containing impurities have molecular weights and chemical structures very similar to those of the oxypropylene group-containing glycol ethers that are the main components, and are difficult to efficiently remove by conventional purification procedures such as distillation. Furthermore, the propylation reaction described in Patent Document 5 is expensive and difficult to mass-produce from an industrial standpoint.

[0028] The content of such allyl group-containing impurities can be easily identified, for example, by nuclear magnetic resonance (NMR) analysis using C as a nuclide. In particular, when the allyl group content is 0.01 mol % or more per mole of oxypropylene groups, there is concern that when the compound is used as a reaction solvent or diluent for a polyether-polysiloxane block copolymer, it may cause a side reaction that inhibits the formation of the block copolymer. Reference Data 1 and Reference Data 2 in the examples of the present application show the results of quantifying allyl group-containing impurities in commercially available oxypropylene group-containing glycol ethers, expressed as the ratio of the number of moles of allyl groups per mole of oxypropylene groups. Commercially available products contain 0.010 to 0.20 mol % of allyl groups per mole of oxypropylene groups, and particularly low-priced BDPG products or BDPG products contain 0.10 to 0.20 mol % of allyl groups. When these products are used as reaction solvents or diluents for polyether-polysiloxane block copolymers, it is highly desirable to reduce the allyl group-containing impurities and purify them using the production method of the present invention described below.

[0029] The production method according to the present invention comprises a reaction step of converting allyl group-containing impurities into hydrosilylation reaction products and reducing the impurities; a step of separating the reaction products by a separation operation such as distillation after the reaction step to purify the oxypropylene group-containing glycol ether; and a step of adding an antioxidant to the oxypropylene group-containing glycol ether at any timing.

[0030] [Hydrosilylation Reaction Step] The hydrosilylation reaction step according to the present invention is a step of subjecting allyl group-containing impurities contained in oxypropylene group-containing glycol ethers to a hydrosilylation reaction with a silicon-bonded hydrogen atom (Si—H)-containing compound, with the objective of inactivating the allyl groups in the allyl group-containing impurities through the reaction and converting the reaction product and the oxypropylene group-containing glycol ethers into components with significantly different molecular weights by adding an Si—H-containing compound, thereby rendering them in a state that can be easily purified by known separation procedures such as distillation. Note that the addition of the Si—H-containing compound to the allyl group-containing impurities does not cause side reactions involving the polyether-polysiloxane block copolymer, and therefore the oxypropylene group-containing glycol ethers may be used without separating the reaction product, as long as it is commercially acceptable and of acceptable quality.

[0031] The silicon-bonded hydrogen atom (Si—H)-containing compound may contain at least one Si—H group in the molecule, and known Si—H-containing organosilicon compounds such as hydridosilanes, hydridosiloxane oligomers, cyclic, linear, or resinous hydrogenpolysiloxanes, and hydrogensilsesquioxanes can be used. However, when the hydrosilylation reaction product with the allyl group-containing impurity is separated by distillation, a non-volatile Si—H-containing organosilicon compound has the advantage that the distillation operation can be carried out extremely simply together with the unreacted Si—H-containing compound. Therefore, the Si—H-containing compound used in the production method of the present invention is preferably non-volatile, and industrially, a methylhydrogenpolysiloxane having a viscosity or degree of polymerization that makes it non-volatile can be used as an example.

[0032] The amount of Si—H-containing compound used is an amount that provides 1 mole or more of Si—H per mole of allyl groups in the allyl group-containing impurities in the oxypropylene group-containing glycol ethers, and may be an amount that provides a slight excess or excess of Si—H within the range of 1 to 20 moles, 2 to 15 moles, or 3 to 10 moles. This is because, as mentioned above, unreacted Si—H-containing compounds such as methylhydrogenpolysiloxane can be separated from the oxypropylene group-containing glycol ethers together with the hydrosilylation reaction product by means of distillation or the like.

[0033] The hydrosilylation reaction step proceeds in the presence of an effective amount of a hydrosilylation catalyst. Such a hydrosilylation catalyst is not particularly limited as long as it can be uniformly dispersed in the oxypropylene group-containing glycol ether, and an appropriate catalyst can be selected from known hydrosilylation catalysts for use in the present invention. Specific examples of the hydrosilylation catalyst include platinum-containing hydrosilylation catalysts such as particulate platinum adsorbed on a silica fine powder or carbon powder support, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, coordination compounds of chloroplatinic acid and vinylsiloxane, and platinum black.

[0034] In the production method of the present invention, particularly suitable hydrosilylation catalysts are neutral platinum complex catalysts, with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex being particularly preferred. On the other hand, when an acidic hydrosilylation catalyst such as chloroplatinic acid or alcohol-modified chloroplatinic acid is used, it may be necessary to use a known buffer component such as a potassium salt or sodium salt, or to increase the amount of the catalyst itself.

[0035] The amount of the hydrosilylation catalyst used is not particularly limited as long as it is an effective amount, but is an amount such that the metal atoms (particularly platinum group metal atoms) in the hydrosilylation catalyst are 0.1 to 1000 ppm by mass, preferably 1 to 100 ppm, when the total mass of the oxypropylene group-containing glycol ethers is taken as 100 mass %. Note that, because the hydrosilylation catalyst is basically non-volatile, it can be separated from the oxypropylene group-containing glycol ethers after the reaction by known separation means such as distillation or filtration.

[0036] The hydrosilylation reaction conditions of the present invention can be selected arbitrarily, but can also be obtained by adding a small amount (approximately 1 pp to 1% by mass) of an antioxidant such as BHT (2,6-di-t-butyl-p-cresol or dibutylhydroxytoluene) or tocopherol (vitamin E) to the oxypropylene group-containing glycol ether, if necessary, and heating and stirring at room temperature to 200°C, preferably 50 to 100°C, in an inert gas atmosphere such as nitrogen. The antioxidant may be added after completion of the hydrosilylation reaction. The reaction time can be selected depending on the reaction scale, the amount of catalyst used, and the reaction temperature, and is generally in the range of several minutes to several hours.

[0037] In the present invention, the reaction is carried out with a slight excess of Si-H groups relative to C=C groups, so the end point of the hydrosilylation reaction can be confirmed by a predetermined reduction in Si-H bond absorption by infrared spectroscopy (IR) or by the following alkaline decomposition gas generation method, whereby the calculated amount of hydrogen gas generated is reduced compared to the initial value. The amount of hydrogen gas generated can also be determined by analyzing the Si-H-containing compound, which is the reaction raw material, using the same method. The outline of this method is as follows: <Alkaline decomposition gas generation method: A solution of a sample dissolved in toluene or IPA is reacted with an ethanol / water mixed solution of 28.5% by mass of caustic potassium at room temperature, and the generated hydrogen gas is collected in a collection tube and its volume is measured.>

[0038] [Purity] In the production method of the present invention, it is preferable that the purity of the oxypropylene group-containing glycol ether after the hydrosilylation reaction step is 90% by mass or more and that it is substantially free of allyl group-containing impurities. Here, "substantially free of allyl group-containing impurities" means that the Si—H-containing compound described above is added in an amount stoichiometrically equivalent to the amount of allyl groups in the allyl group-containing impurities (i.e., a molar ratio of 1:1), and as described above, the hydrosilylation reaction product no longer falls under the category of allyl group-containing impurities. The purity of the oxypropylene group-containing glycol ether is preferably 95% by mass or more. From the perspective of use as a reaction solvent or diluent for polyether-polysiloxane block copolymers, it is particularly preferable that the hydrosilylation reaction product, unreacted Si—H-containing compound, hydrosilylation reaction catalyst, etc. are separated and the oxypropylene group-containing glycol ether is purified to a purity of 95 to 99.9% by mass after the purification step described below.

[0039] [Purification Step] The method for producing oxypropylene group-containing glycol ethers according to the present invention preferably includes a step of separating the oxypropylene group-containing glycol ethers from the hydrosilylation reaction product after the hydrosilylation reaction step, and purifying the resulting oxypropylene group-containing glycol ethers to a high purity that is substantially free of allyl group-containing impurities (i.e., allyl group-free). In the purification step, it is preferable to separate the unreacted Si—H-containing compound and the hydrosilylation reaction catalyst together. This is because these components may also be substances that cause side reactions when used as a reaction solvent or diluent for polyether-polysiloxane block copolymers.

[0040] The separation means used in the purification step can be selected appropriately depending on the properties of the Si—H-containing compound used in the hydrosilylation reaction step (particularly molecular weight and whether or not it is volatile) and the properties of the hydrosilylation reaction product (particularly molecular weight and whether or not it is volatile), but it is particularly preferred to include a distillation step, because the reaction can be designed so that the hydrosilylation reaction product has a molecular weight and boiling point significantly different from those of oxypropylene group-containing glycol ethers. In particular, if a non-volatile component is selected as the Si—H-containing compound, the hydrosilylation reaction product will often also be substantially non-volatile, which has the advantage that only the oxypropylene group-containing glycol ethers can be separated and purified to an extremely high purity even with a simple distillation step and distillation equipment.

[0041] The distillation step can be carried out by a known method. If the Si—H-containing compound and the hydrosilylation reaction product are substantially non-volatile, they can often be purified to a high purity simply by heating and distilling under reduced pressure. However, industrially, the distillation pressure is, for example, 0.01 mmHg or more and 100 mmHg or less, preferably 50 mmHg or less, and more preferably 10 mmHg or less, under an inert gas atmosphere such as nitrogen. The distillation temperature is, for example, 60 to 200°C, preferably 100 to 190°C, and more preferably 120 to 180°C. The reduced-pressure distillation time is generally designed to be in the range of 30 minutes to several tens of hours, depending on the purification scale and the reduced-pressure conditions.

[0042] The purification step may consist of only a distillation step. However, when coloration of the oxypropylene group-containing glycol ether or contamination with solid residues is observed, a filtration operation may be carried out at room temperature and normal pressure, or under increased or reduced pressure, using a known filtering material such as filter paper, a zeta potential adsorptive filter, a bag filter, a cartridge filter, an adsorbent, or a filter aid.

[0043] [Antioxidant Addition Step] The method for producing oxypropylene group-containing glycol ethers according to the present invention may include a step of adding a known antioxidant at any timing. The antioxidant may be added before or after the hydrosilylation reaction. Furthermore, the antioxidant may be added to the oxypropylene group-containing glycol ethers separated from other components after the purification step. In addition, the antioxidant does not need to be added all at once, and may be added at multiple timings, without any particular limitation. For example, an antioxidant may be added to the reaction system before the hydrosilylation reaction, and then the same or different antioxidant may be added to the oxypropylene group-containing glycol ethers after the purification step. Note that the addition of an antioxidant is highly preferable in that it not only prevents oxidative degradation of the oxypropylene group-containing glycol ethers themselves, but also prevents oxidative degradation of the copolymer during and after polymerization when the oxypropylene group-containing glycol ethers are used as a reaction solvent or diluent for polyether-polysiloxane block copolymers.

[0044] The type of antioxidant is not particularly limited as long as it does not adversely affect the hydrosilylation reaction, and therefore, phenolic antioxidants, vitamins, etc. can be added to improve oxidation stability. Examples of such antioxidants that can be used include BHT and vitamin E.

[0045] The amount of antioxidant added is optional, but it is preferably contained in the range of 1 to 10,000 ppm (=1.0 mass %) relative to the oxypropylene group-containing glycol ether, and particularly preferably in the range of 50 to 500 ppm.

[0046] [Buffering Agent] A known buffering agent may be added to the oxypropylene group-containing glycol ether of the present invention in the above-mentioned production process. The use of a buffering agent may inhibit an increase in the overall acid value, particularly due to the oxypropylene group-containing compound, the Si—H-containing compound, the hydrosilylation reaction catalyst, and the like, thereby stabilizing the quality. Examples of buffering agents include known potassium salts such as potassium carbonate and known sodium salts such as sodium acetate. Note that some soluble potassium salts function as buffering agents, and in addition to stabilizing the quality of the oxypropylene group-containing glycol ether itself, they may also further improve the foam-stabilizing performance when the oxypropylene group-containing glycol ether is used as a reaction solvent or diluent for a polyether-polysiloxane block copolymer.

[0047] For the purpose of terminating the hydrosilylation reaction and inactivating the catalyst, a known curing inhibitor may be added to the bottoms after the hydrosilylation reaction or after purification, or to the bottoms after drumming. Examples of such curing inhibitors include acetylene compounds, enyne compounds, organic nitrogen compounds, organic phosphorus compounds, oxime compounds, and phosphorus compounds. Small amounts of the components described in JP 2007-308542 A, such as 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane, may also be added.

[0048] [Method for Producing Polyether-Polysiloxane Block Copolymer Composition] The oxypropylene group-containing glycol ethers obtained by the above-described production method can be suitably used as reaction solvents or diluents for polyether-polysiloxane block copolymers obtained by the hydrosilylation reaction of an organopolysiloxane containing SiH groups at both ends and a polyether containing methallyl groups at both ends. In particular, the oxypropylene group-containing glycol ethers obtained by the above-described production method can be easily and efficiently produced to a high purity and substantially free of allyl group-containing impurities (i.e., allyl group-free). This prevents a side reaction in which only one terminal allyl group derived from the impurity is added to the organopolysiloxane containing SiH groups at both ends, thereby inhibiting the formation of the block copolymer. This has the practical benefit of enabling the stable production of polyether-polysiloxane block copolymers with higher molecular weights and higher viscosities. The above reaction can be carried out without particular limitations, by replacing the glycol ethers in the reaction proposed by the present applicants in Patent Document 10 with the production method of the present invention. In particular, the average molecular weight of the copolymer can be designed by adjusting the molar ratio (reaction ratio) of the organopolysiloxane containing SiH groups at both ends and the polyether containing alkenyl groups at both ends. Furthermore, the surfactant activity and affinity for urethane foam systems can be controlled by adjusting the EO percentage and size of the polyether moiety and by introducing hydroxyl groups or hydrophobic groups into the copolymer terminals. The copolymer can exhibit excellent effects as a surfactant for bubble control or bubble stabilization in various types of polyurethane foam formulations.

[0049] [Method for Producing Polyurethane Foam-Forming Composition] The oxypropylene group-containing glycol ethers obtained by the above-described production method can be suitably used as a reaction solvent or diluent for the (AB) n-type polyether-modified silicone foam stabilizer comprising the polyether-polysiloxane block copolymer described in, for example, Patent Document 10. Therefore, a polyurethane foam-forming composition can be produced by mixing (a) a polyol, (b) a polyisocyanate, (c) a catalyst, (d) the (AB) n-type polyether-modified silicone foam stabilizer comprising the oxypropylene group-containing glycol ether obtained by the above-described production method, and (e) optionally at least one additional component selected from the group consisting of foam stabilizers other than component (d), blowing agents, diluents, chain extenders, crosslinking agents, water, non-aqueous blowing agents, fillers, reinforcing agents, pigments, dyes, colorants, flame retardants, antioxidants, antiozonants, UV stabilizers, antistatic agents, bactericides, and antibacterial agents.

[0050] [Other Applications] The oxypropylene group-containing glycol ethers obtained by the above-described production method are highly pure and substantially free of allyl group-containing impurities (i.e., allyl group-free), and can be used for known applications of oxypropylene group-containing glycol ethers without any particular restrictions.

[0051] The polyether-polysiloxane block copolymer obtained by the above-described production method has the advantage that side reactions are suppressed and that a high-molecular-weight, high-viscosity polyether-polysiloxane block copolymer can be easily and stably produced. Therefore, the polyether-polysiloxane block copolymer can be used without particular limitation for applications of conventionally known polyether-polysiloxane block copolymers, and can be used without particular limitation as a surfactant, a foam stabilizer, an agent for imparting lubricity or softening to fibers, a surface treatment or coating agent, a reactive raw material for other polymer materials, and the like.

[0052] In particular, polyether-polysiloxane block copolymer compositions containing oxypropylene group-containing glycol ethers obtained by the production method of the present invention as a reaction solvent or diluent are useful as industrial surfactants, and can be blended into paints, coating agents, building materials, hydrophilicity-imparting agents, surface treatment agents, foamable resin compositions, etc., without particular limitation. Furthermore, due to their function as surfactants, they are particularly useful as paint additives, emulsifiers, solubilizers, foam stabilizers for polyurethane foams, and additives to premix liquids for polyurethane foams.

[0053] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. ３ SiO group (or Me ３ (Si group) as “M”, Me ２ The SiO group is represented as "D ," and the MeHSiO group is represented as "M Ｈ ", and a unit in which the methyl groups in M ​​and D are modified by any of the substituents is represented as M Ｒ and D Ｒ In addition, IPA represents isopropanol, MeOH represents methanol, BDPG represents dipropylene glycol monobutyl ether, BTPG represents tripropylene glycol monobutyl ether, EO represents ethylene oxide or an oxyethylene group, and PO represents a propylene oxide or an oxypropylene group. In the experimental examples, "%" means mass % unless otherwise specified. The number of moles (mol%) of allyl groups per mole of oxypropylene group (PO) shown in the reference data of Tables 1 and 2 is an identified value based on the results of the inventors' analysis of commercially available products by 13C-NMR.

[0054] The differences in quality between BDPG and BTPG suppliers are shown in Reference Data 1 (Table 1) and Reference Data 2 (Table 2) below. Company H's products are high-priced, while Company L's products are low-priced. In the following experimental examples, when BDPG manufactured by Company H or Company L is used, it will be referred to as "BDPG (Company H)" or "BDPG (Company L)." When BTPG manufactured by Company H or Company L is used, it will be referred to as "BTPG (Company H)" or "BTPG (Company L)." While the supplier's CoA information indicates that these products differ in purity, water content, acid value, etc., there was no information regarding the amount of allyl-containing impurities. Therefore, the allyl group / PO (mol%) determined by the above-mentioned C-NMR is listed in each table.

[0055] <Reference Data 1> [Table 1]: Differences in quality depending on BDPG supplier

[0056] <Reference Data 2> [Table 2]: Differences in quality depending on BTPG suppliers

[0057] In the following Examples 1 to 3, the allyl group-containing impurities contained in BTPG (Company L) and BDPG (Company L) were reduced and purified using the production method of the present invention. Furthermore, in Examples 4 to 6, BTPG or BDPG obtained by the production method of the present invention was used as a reaction solvent and diluent to synthesize an (AB)n-type polyether-modified silicone foam stabilizer, which is a polyether-polysiloxane block copolymer composition. For reference, in Reference Examples 1 to 3, commercially available BTPG or BDPG was used as a reaction solvent and diluent to synthesize an (AB)n-type polyether-modified silicone foam stabilizer.

[0058] The raw material components used in these experiments are as follows: (a1-1) Average composition formula CH ２ =C(CH ３ ) CH ２ -O(C ２ H ４ O) ３９ (C ３ H ６ O) ２０ -CH ２ -C(CH ３ ) = CH２ Bismethallyl polyether (degree of unsaturation: 0.68 meq / g, hydroxyl value: 0.8 mg-KOH / g) represented by the average composition formula CH ２ =C(CH ３ ) CH ２ -O(C ２ H ４ O) ３９ (C ３ H ６ O) ２０ -CH ２ -C(CH ３ ) = CH ２ We used bismethallyl polyether (degree of unsaturation: 0.66 meq / g, hydroxyl value: 1.1 mg-KOH / g) expressed as follows. *Note: (a1-1) to (a1-2) correspond to different lots of bismethallyl polyether raw materials. Here, the polyether portion is a random adduct of ethylene oxide and propylene oxide.

[0059] (a2-1) Average composition formula M after low boiling point removal treatment Ｈ D 2０ M Ｈ Methylhydrogenpolysiloxane (silicon-bonded hydrogen content 0.125%) represented by the average composition formula M Ｈ D 2０ M Ｈ Methylhydrogenpolysiloxane (silicon-bonded hydrogen content 0.128%) represented by the average composition formula M Ｈ D 2０ M Ｈ Methyl hydrogen polysiloxane (silicon-bonded hydrogen content 0.129%) and *Note: (a2-1) to (a2-3) correspond to different lots of methyl hydrogen polysiloxane raw materials. Hydrosilylation reaction catalyst: 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex ligand solution (Pt concentration 4.3 wt%)

[0060] Example 1: Production of BTPG (Example 1) by Purifying BTPG (Company L) A 2-L reactor was charged with 18.0 g (1.0% of the total) of (a2-3) methylhydrogenpolysiloxane, 1,795.6 g (99.0% of the total) of BTPG (Company L), and 0.43 g of a hydrosilylation catalyst. Heating was initiated with stirring under a nitrogen gas flow. The calculated SiH / C=C molar ratio was 6.3. The mixture was aged at 80-90°C for 3 hours to consume allyl groups derived from allyl-containing impurities in the BTPG. The calculated purity of BTPG at this stage was 96%. This purity is equivalent to the purity of the supplier's CoA.

[0061] Next, the entire separable flask, from the upper connecting tube to the distillation head, was wrapped in a ribbon heater and covered with heat insulating material to prevent air cooling due to the ambient temperature. The ribbon heater was set to 130°C and the oil bath was set to 150-170°C, and the flask was stirred under a nitrogen flow while the pressure inside the flask was reduced to 10 mmHg or less, and the distilled BTPG was collected in the flask. Distillation began when the internal liquid temperature was around 150°C, and this state was maintained for a total of approximately 12 hours, yielding 1,589 g of BTPG (Example 1).

[0062] Example 2: Production of BTPG (Example 2) by Purifying BTPG (Company L) A 3-L reactor was charged with 28.0 g (1.0% of the total) of (a2-3) methylhydrogenpolysiloxane and 2,804.6 g (99.0% of the total) of BTPG (Company L). The mixture was heated to 75°C with stirring under a nitrogen gas flow. The calculated SiH / C=C molar ratio was 6.3. 0.67 g of a hydrosilylation catalyst was added, and the mixture was aged at 75-90°C for 5 hours to consume allyl groups derived from allyl-containing impurities in the BTPG. The calculated purity of BTPG at this stage was 96%. This purity is equivalent to the purity of the supplier's CoA.

[0063] Next, the entire separable flask, from the upper connecting tube to the distillation head, was wrapped in a ribbon heater and covered with heat insulating material to prevent air cooling due to the ambient temperature. The ribbon heater was set to 130°C and the oil bath was set to 150-170°C, and the flask was stirred under a nitrogen flow while the pressure inside the flask was reduced to 10 mmHg or less, and the distilled BTPG was collected in the flask. Distillation began when the internal liquid temperature was around 150°C, and this state was maintained for a total of approximately 16 hours, yielding 2,695 g of BTPG (Example 2).

[0064] Example 3: Production of BDPG (Example 3) by Purification of BDPG (Company L) A 2-L reactor was charged with 12.0 g (1.0% of the total) of (a2-3) methylhydrogenpolysiloxane, 1,188.0 g (99.0% of the total) of BDPG (Company L), and 0.28 g of a hydrosilylation catalyst. The mixture was heated to 75°C with stirring under a nitrogen gas flow. The calculated SiH / C=C molar ratio was 6.4. The mixture was aged at 75-90°C for 2.5 hours to consume allyl groups derived from allyl-containing impurities in the BDPG. The calculated purity of the BDPG at this stage was 98%. Here, this purity is synonymous with the purity of the supplier's CoA.

[0065] Next, the entire separable flask, from the upper connecting tube to the distillation head, was wrapped in a ribbon heater and covered with heat insulating material to prevent air cooling due to the ambient temperature. The ribbon heater was set to 125°C and the oil bath was set to 125-135°C, and the flask was stirred under a nitrogen flow while the pressure inside the flask was reduced to 12 mmHg or less, and the distilled BDPG was collected in the flask. Distillation began when the internal liquid temperature was around 125°C, and this state was maintained for approximately 2.5 hours, yielding 1,167 g of BDPG according to the present invention (Example 3).

[0066] The quantitative results of the allyl groups remaining in the high-purity BTPG of Examples 1 and 2 obtained by the production method of the present invention are summarized below in comparison with BTPG (Company H) and BTPG (Company L). Note that no propenyl group signal resulting from isomerization of the allyl groups was observed in these samples. [Table 3]: Analysis results of allyl groups in BTPG ( 13C NMR)

[0067] The quantitative results of the allyl groups remaining in the high-purity BDPG of Example 3 obtained by the production method of the present invention are summarized below in comparison with BDPG (Company H) and BDPG (Company L). Note that no propenyl group signal resulting from isomerization of the allyl groups was observed in these samples. [Table 4]: Analysis results of allyl groups in BDPG ( 13 C NMR)

[0068] Next, BTPG (Company H), BTPG (Company L), and BTPG (Example 1) were used as both the reaction solvent and diluent to synthesize (AB) n-type polyether-modified silicone foam stabilizer. Here, the molar ratio of C═C groups to Si—H groups in the polyether raw material was fixed at C═C / SiH = 1.05 for each experiment. [Reference Example 1] 34.18 g of (a1-1) bismethallyl polyether (containing 500 ppm of natural vitamin E), 0.04 g of a 10 wt. % solution of sodium acetate in MeOH, and 0.10 g of natural vitamin E were charged into a 500 mL reactor, and heating was initiated with stirring under a nitrogen flow. MeOH was removed from the system by stripping at 30-60°C and 58 mmHg for 1 hour. The pressure was restored, and 17.17 g of (a2-3) methylhydrogenpolysiloxane and 154.05 g of BTPG (H Company) were added with stirring, and 0.18 mμL of a hydrosilylation reaction catalyst was added. The reaction was carried out at 60 to 80°C for 2 hours, and the reaction was completed. (where a = 20, x1 = 39, y1 = 20, n > 10) and BTPG in a ratio of 25:75, a transparent, liquid (AB)n-type polyether-modified silicone foam stabilizer "970 mm2 / s (25°C)" was obtained.

[0069] Reference Example 2: A 1-L reactor was charged with 58.80 g of (a2-2) methylhydrogenpolysiloxane, 116.20 g of (a1-1) bismethallyl polyether (containing 500 ppm of natural vitamin E), and 0.14 g of a 10 wt. % MeOH solution. Heating was initiated with stirring under a nitrogen flow. MeOH was removed from the system by stripping for 30 minutes under conditions of 70-80°C and 20-25 mmHg. The pressure was restored, and 525 g of BTPG (manufactured by L Co.) was added with stirring. 0.16 g of a hydrosilylation catalyst was then added, and the reaction was carried out at 80-90°C for 3 hours, resulting in completion of the reaction. This gave a product with the average composition formula: (where a = 20, x1 = 39, y1 = 20, n ≈ 8) A transparent, liquid (AB)n-type polyether-modified silicone foam stabilizer "171 mm2 / s (25°C)" was obtained, which contained BTPG and a linear organopolysiloxane-polyether block copolymer in a ratio of 25:75.

[0070] Example 4: A 1-L reactor was charged with 66.96 g of (a2-1) methylhydrogenpolysiloxane, 133.04 g of (a1-2) bismethallyl polyether (containing 500 ppm of natural vitamin E), and 0.16 g of a 10 wt. % MeOH solution. Heating was initiated with stirring under a nitrogen flow. MeOH was removed from the system by stripping for 40 minutes under conditions of 50-75°C and 5 mmHg. The pressure was restored, and 600 g of BTPG (Example 1) was added with stirring. 0.048 g of a hydrosilylation catalyst was then added, and the reaction was carried out at 70-80°C for 3 hours, resulting in completion of the reaction. This gave a product with the average composition formula: (where a = 20, x1 = 39, y1 = 20, n > 10) and BTPG in a ratio of 25:75, a transparent, liquid (AB)n-type polyether-modified silicone foam stabilizer "626 mm2 / s (25°C)" was obtained.

[0071] Next, BDPG (Company H) and BDPG (Example 3) were used as both the reaction solvent and diluent to synthesize (AB) n-type polyether-modified silicone foam stabilizer. [Reference Example 3] 66.96 g of (a2-1) methylhydrogenpolysiloxane, 133.04 g of (a1-2) bismethallyl polyether (containing 500 ppm of natural vitamin E), 0.16 g of a 10 wt. % MeOH solution, and 200 g of BDPG (Company H) were charged into a 1-L reactor, and heating was initiated with stirring under a nitrogen flow. MeOH was removed from the system by stripping for 40 minutes under conditions of 70-80°C and 16 mmHg. The pressure was restored, and 0.106 mL of a hydrosilylation catalyst was added. The reaction was carried out at 70-80°C for 3 hours, resulting in completion. Further, 400 g of BDPG (Company H) was added and mixed, resulting in a transparent, liquid (AB)n-type polyether-modified silicone foam stabilizer "427 mm2 / s (25°C)" containing the same linear organopolysiloxane-polyether block copolymer as in Reference Example 3 and BDPG in a ratio of 25:75. Here, the molar ratio of C=C groups to Si-H groups in the polyether raw material was C=C / SiH=1.05.

[0072] Example 5: A 500 mL reactor was charged with 25.56 g of (a2-1) methylhydrogenpolysiloxane, 49.44 g of (a1-2) bismethallyl polyether (containing 500 ppm of natural vitamin E), 0.06 g of a 10 wt. % MeOH solution of sodium acetate, and 75.0 g of BDPG (Example 3). Heating was initiated with stirring under a nitrogen flow. MeOH was removed from the system by stripping for 15 minutes at 50-75°C and 15 mmHg. The pressure was restored, and 0.04 mL of a hydrosilylation catalyst was added. The reaction was continued for 3 hours at 70-80°C, resulting in completion of the reaction. Further, 150 g of BDPG (Example 3) was added and mixed, resulting in a transparent liquid (AB)n-type polyether-modified silicone foam stabilizer "650 mm / s (25°C)" containing the same linear organopolysiloxane-polyether block copolymer as in Reference Example 3 and BDPG in a ratio of 25:75. Here, the molar ratio of C=C groups to Si-H groups in the polyether raw material was C=C / SiH=1.02.

[0073] [Summary] As shown in Examples 1 to 3, it was possible to purify low-cost BDPG or BTPG using the production method of the present invention, and to obtain oxypropylene group-containing glycol ethers having a sufficiently low allyl group / PO (mol %) and a sufficiently reduced amount of allyl group-containing impurities for practical use, which compare favorably with high-cost, high-purity commercially available products.

[0074] Furthermore, as shown in Examples 4 and 5, BDPG or BTPG obtained using the above-mentioned production method was used as a reaction solvent and diluent to synthesize an (AB)n-type polyether-modified silicone foam stabilizer. The foam stabilizers according to these Examples have sufficient viscosity and suppressed side reactions, even compared to the synthesis examples performed as reference experiments (Reference Examples 1 and 3) using a high-priced, high-purity commercially available product manufactured by Company H. The production method according to the present invention makes it possible to stably produce high-quality (AB)n-type polyether-modified silicone foam stabilizers. On the other hand, when low-priced BTPG manufactured by Company L is used as the reaction solvent and diluent (Reference Example 2), the resulting (AB)n-type polyether-modified silicone foam stabilizer has a significantly low viscosity, and there is a strong concern that it will not have sufficient foam-stabilizing performance due to side reactions derived from allyl group-containing impurities, making it difficult to produce a stable product with stable quality.

Claims

1. A method for producing oxypropylene group-containing glycol ethers, the method comprising the step of subjecting an allyl group-containing impurity contained in an oxypropylene group-containing glycol ether, the oxypropylene group-containing glycol ether having a terminal hydrogen atom substituted with a hydrocarbon group having 1 to 8 carbon atoms and an alcoholic hydroxyl group at the other terminal, the number of repeating oxyalkylene units having 2 to 4 carbon atoms being in the range of 1 to 3, and containing no heteroatoms other than oxygen, to a hydrosilylation reaction with a silicon-bonded hydrogen atom (Si—H)-containing compound.

2. 2. The method for producing an oxypropylene group-containing glycol ether according to claim 1, wherein the purity after the hydrosilylation reaction step is 90% by mass or more and the product is substantially free of allyl group-containing impurities.

3. 2. The method for producing an oxypropylene group-containing glycol ether according to claim 1, further comprising a purification step of separating the oxypropylene group-containing glycol ether from the hydrosilylation reaction product after the hydrosilylation reaction step.

4. 4. The method for producing oxypropylene group-containing glycol ethers according to claim 3, wherein the purification step includes a distillation step of the oxypropylene group-containing glycol ethers.

5. 2. The method for producing an oxypropylene group-containing glycol ether according to claim 1, wherein the silicon-bonded hydrogen atom (Si—H)-containing compound used in the hydrosilylation reaction step is a non-volatile polysiloxane containing one or more Si—H groups per molecule.

6. 2. The method for producing oxypropylene group-containing glycol ethers according to claim 1, wherein the molar ratio of the remaining C=C groups to the oxypropylene groups is 1 / 2500 (0.04 mol %) or less.

7. 2. The method for producing an oxypropylene group-containing glycol ether according to claim 1, wherein the purity of the oxypropylene group-containing glycol ether obtained after the hydrosilylation reaction step is 95% by mass or more.

8. 2. The method for producing an oxypropylene group-containing glycol ether according to claim 1, wherein the oxypropylene group-containing glycol ether is one or more glycol ethers selected from propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monopropyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, and tripropylene glycol monoethyl ether.

9. 2. The method for producing an oxypropylene group-containing glycol ether according to claim 1, further comprising the step of adding 1 ppm to 1% by mass of an antioxidant to the oxypropylene group-containing glycol ether at any timing.

10. A method for producing a polyether-polysiloxane block copolymer composition, characterized in that the oxypropylene group-containing glycol ether obtained by the method for producing an oxypropylene group-containing glycol ether according to any one of claims 1 to 9 is used as a reaction solvent or diluent.

11. A method for producing a polyurethane foam-forming composition, comprising using an oxypropylene group-containing glycol ether obtained by the method for producing an oxypropylene group-containing glycol ether according to any one of claims 1 to 9 as a reaction solvent or diluent for a polyether-polysiloxane block copolymer.

12. The molar ratio of residual C═C groups to oxypropylene groups is 1 / 2500 (0.04 mol %) or less, the glycol ether is substantially free of allyl group-containing impurities, and optionally contains 1 ppm to 1% of an antioxidant, the purity of which is 95 mass % or more, and the glycol ether is one or more oxypropylene group-containing glycol ethers selected from propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monopropyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, and tripropylene glycol monoethyl ether, or a mixture thereof.