Method for producing oxyalkylene polymers having hydroxyl groups

Abstract

The present invention provides a method for producing an oxyalkylene polymer having a hydroxyl group, in which an alkylene oxide is used as an initiator in a highly active state of the complex metal cyanide catalyst and capable of ring-opening addition polymerization. [Solution] A method for producing an oxyalkylene polymer having a hydroxyl group, comprising ring-opening addition polymerization of an alkylene oxide to an initiator containing a compound having an active hydrogen group (excluding α-hydroxy-ω-hydroxypoly(oxybutane-1,4-diyl), pentane-1,5-diol, and decane-1,10-diol) in the presence of a complex metal cyanide catalyst, wherein the molecular weight per active hydrogen of the compound having an active hydrogen group is 50 or more, and the pH of the initiator is 4.0 or more and 8.0 or less.

Description

[Technical Field]

[0001] This invention relates to an oxyalkylene polymer having a hydroxyl group. [Background technology]

[0002] Oxyalkylene polymers containing hydroxyl groups are produced by ring-opening addition polymerization of alkylene oxide to an initiator containing a compound with an active hydrogen group in the presence of a catalyst. Complex metal cyanide catalysts are known as catalysts for obtaining oxyalkylene polymers containing hydroxyl groups with a small molecular weight distribution. However, when the molecular weight of the compound containing the active hydrogen group is small, ring-opening addition polymerization does not proceed easily with complex metal cyanide catalysts. Therefore, basic catalysts such as potassium hydroxide are used to perform ring-opening addition polymerization of alkylene oxide to an initiator to raise the molecular weight of the initiator to a certain level beforehand, and then complex metal cyanide catalysts are used to produce oxyalkylene polymers containing hydroxyl groups.

[0003] For example, Patent Document 1 describes the polymerization of propylene oxide using a zinc hexacyanocobaltate grime complex catalyst with a polyoxypropylene diol having a number average molecular weight of approximately 4,500 as an initiator. It is believed that this initiator was obtained by ring-opening addition polymerization of propylene oxide to a low molecular weight diol compound using a basic catalyst. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-132732 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] When hydroxyalkylene polymers containing hydroxyl groups are produced using only basic catalysts such as potassium hydroxide, the molecular weight distribution of the resulting hydroxyalkylene polymers becomes large. Furthermore, when the molecular weight of the initiator is first set to a certain level using a basic catalyst such as potassium hydroxide, and then a complex metal cyanide catalyst is used to produce hydroxyalkylene polymers containing hydroxyl groups, the process becomes multi-step and inefficient. Therefore, even when the molecular weight of the compound containing the active hydrogen group is small, reaction conditions are sought that allow ring-opening addition polymerization to proceed using a complex metal cyanide catalyst.

[0006] The present invention aims to provide a method for producing an oxyalkylene polymer having a hydroxyl group that allows ring-opening addition polymerization of alkylene oxide to an initiator containing a compound having an active hydrogen-containing group while the complex metal cyanide catalyst is highly active, compared to conventional methods. [Means for solving the problem]

[0007] The present invention is as follows [1] to [5]. [1] A method for producing an oxyalkylene polymer having a hydroxyl group, comprising ring-opening addition polymerization of an alkylene oxide to an initiator containing a compound having an active hydrogen group (excluding α-hydroxy-ω-hydroxypoly(oxybutane-1,4-diyl), pentane-1,5-diol, and decane-1,10-diol) in the presence of a complex metal cyanide catalyst, wherein the molecular weight per active hydrogen of the compound having an active hydrogen group is 50 or more, and the pH of the initiator is 4.0 or more and 8.0 or less. [2] The method for producing an oxyalkylene polymer having a hydroxyl group according to [1], wherein the molecular weight per active hydrogen of the compound having the active hydrogen group is 400 or less. [3] A method for producing an oxyalkylene polymer having a hydroxyl group according to [1] or [2], wherein the water content relative to the total mass of the initiator is 0.01% by mass or less. [4] A method for producing an oxyalkylene polymer having a hydroxyl group according to any one of [1] to [3], wherein the basicity (CPR) of the initiator is 10 or less. [5] A method for producing an oxyalkylene polymer having hydroxyl groups according to any one of [1] to [4], wherein the amount of the complex metal cyanide catalyst used relative to the total mass of the oxyalkylene polymer having hydroxyl groups is 200 ppm by mass or less. [Effects of the Invention]

[0008] According to the present invention, a method for producing an oxyalkylene polymer having a hydroxyl group that can be ring-opening addition polymerized by an alkylene oxide to an initiator containing a compound having an active hydrogen-containing group in a highly active state of the complex metal cyanide catalyst is provided. [Modes for carrying out the invention]

[0009] The meanings and definitions of terms used in this specification are as follows: A numerical range represented by "~" means a range of numbers whose lower and upper limits are the numbers before and after the "~". The "units" that constitute an oxyalkylene polymer having a hydroxyl group refer to atomic groups directly formed by ring-opening addition polymerization of alkylene oxides. "Hydroxyalkylene polymers" refer to polymers having polyoxyalkylene chains formed from hydroxyl groups and alkylene oxide-based units.

[0010] An "active hydrogen-containing group" is at least one group selected from the group consisting of a hydroxyl group, carboxyl group, amino group, monovalent functional group obtained by removing one hydrogen atom from a primary amine, hydrazide group, and sulfanyl group, all of which are bonded to a carbon atom. "Active hydrogen" refers to hydrogen atoms based on the active hydrogen-containing group described above.

[0011] The "pH" of the initiator is a value measured in accordance with "Part 5: Method for determining color number, viscosity, acid value and pH" of JIS K 1557-3:2007. The "basicity" of the initiator is a value measured in accordance with "Part 4: Method for Determining Basicity" of JIS K 1557-3:2007. The "moisture content" of the initiator is a value measured in accordance with "Part 2: Method for Determining Water Content" of JIS K 1557-2:2007. Note that the "pH", "basicity", and "moisture content" of the initiator are measured after charging the initiator containing a compound having an active hydrogen-containing group into the reactor used once.

[0012] The "hydroxyl value" of the compound having an active hydrogen-containing group and the oxyalkylene polymer having a hydroxyl group contained in the initiator is a value measured in accordance with Method B (phthalation method) described in JIS K 1557-1:2007. The molecular weight in terms of hydroxyl value of the compound having an active hydrogen-containing group and the oxyalkylene polymer having a hydroxyl group contained in the initiator is a value calculated by 56,100 × number of active hydrogens / hydroxyl value.

[0013] The number average molecular weight (hereinafter referred to as "Mn") and the weight average molecular weight (hereinafter referred to as "Mw") of the oxyalkylene polymer having a hydroxyl group are polystyrene-equivalent molecular weights obtained by GPC measurement. The molecular weight distribution is a value calculated from Mw and Mn, and is the ratio of Mw to Mn (hereinafter referred to as "Mw / Mn").

[0014] The viscosity of the oxyalkylene polymer having a hydroxyl group can be measured using an E-type viscometer.

[0015] ≪Method for Producing Oxyalkylene Polymer Having Hydroxyl Group≫ The method for producing the hydroxyl group-containing oxyalkylene polymer of this embodiment involves ring-opening addition polymerization of an alkylene oxide to an initiator containing a compound having an active hydrogen group in the presence of a complex metal cyanide catalyst. The molecular weight per active hydrogen of the compound having an active hydrogen group is 50 or more. The pH of the initiator is 4.0 to 8.0. However, α-hydroxy-ω-hydroxypoly(oxybutane-1,4-diyl), pentane-1,5-diol, and decane-1,10-diol are excluded from the compound having an active hydrogen group.

[0016] (Initiator) The initiator contains a compound having an active hydrogen-containing group. In addition to the above compound, the initiator contains trace amounts of impurities such as water, acidic substances, and basic substances. These impurities originate from either the production of the above compound (e.g., the catalyst and solvent used during production) or from the reactor used in the reaction, or both. The initiator may also contain an acid or base for pH adjustment, as described later.

[0017] According to the inventors' studies, it was found that when the pH of the initiator at the time the initiator is charged into the reactor is less than 4.0 or greater than 8.0, the reaction does not proceed even when ring-opening addition polymerization of alkylene oxide to an initiator containing a low molecular weight active hydrogen-containing group using a complex metal cyanide catalyst. On the other hand, it was found that the above ring-opening addition polymerization proceeds when the pH of the initiator at least at the time the initiator is charged into the reactor is adjusted to between 4.0 and 8.0. In other words, it was found that by setting the pH of the initiator within an appropriate range, the complex metal cyanide catalyst is less likely to be deactivated and can maintain a highly active state.

[0018] The molecular weight per active hydrogen of a compound having an active hydrogen-containing group is 50 or more, preferably 50 to 400, more preferably 50 to 220, and even more preferably 50 to 100. The molecular weight of a compound having an active hydrogen-containing group is expressed as formula weight or molecular weight on a hydroxyl value basis. Ring-opening addition polymerization proceeds easily when the molecular weight per active hydrogen is above the lower limit mentioned above. By controlling the pH of the initiator to an appropriate range, ring-opening addition polymerization can proceed even when the molecular weight per active hydrogen is below the upper limit mentioned above.

[0019] The number of active hydrogens in the compound having an active hydrogen-containing group is equal to the number of hydroxyl groups in the resulting hydroxyl group-containing oxyalkylene polymer. The number of active hydrogens in the compound having an active hydrogen-containing group is not particularly limited and is determined based on the intended use of the hydroxyl group-containing oxyalkylene polymer, but is preferably 1 to 12, more preferably 2 to 8, and particularly preferably 2 to 6.

[0020] The pH of the initiator is 4.0 to 8.0, more preferably 4.0 to 7.5, and even more preferably 4.5 to 7.3. When the pH is within the above range, the complex metal cyanide catalyst is less likely to deactivate and can easily maintain a highly active state. As a result, ring-opening addition polymerization proceeds more easily.

[0021] The pH of the initiator may be adjusted by adding an acid or a base. Examples of acids include mineral acids such as phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphate, hydrochloric acid, sulfuric acid, and sulfite; and organic acids such as formic acid, oxalic acid, succinic acid, acetic acid, maleic acid, benzoic acid, p-toluenesulfonic acid, and dodecylbenzenesulfonic acid. Examples of bases include alkali metal hydroxides or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide; alkali metal carbonates or alkaline earth metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, and barium carbonate; alkali metal bicarbonates or alkaline earth metal bicarbonates such as lithium bicarbonate, potassium bicarbonate, sodium bicarbonate, and cesium bicarbonate; phosphates such as dilithium phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, lithium monohydrogen phosphate, sodium monohydrogen phosphate, and sodium acid pyrophosphate; bisulfates such as lithium bisulfate, sodium bisulfate, and potassium bisulfate; fatty acid amines such as ethylenediamine, diethylenetriamine, and hexamethylenediamine; aromatic amines such as tolylenediamine and diphenylmethanediamine; and organic alkaline compounds such as alkanolamines.

[0022] The water content relative to the total mass of the initiator is preferably 0.01% by mass or less, more preferably 0.008% by mass or less, and even more preferably 0.005% by mass or less. The lower limit of the water content is not particularly limited, but may be 0.0001% by mass or more, or 0.001% by mass or more. According to the inventors' studies, it was found that lowering the water content of the initiator further facilitates ring-opening addition polymerization. Specifically, it was found that by setting the water content of the initiator to an appropriate value, the complex metal cyanide catalyst is less likely to deactivate and can maintain a highly active state. When the water content is below the above upper limit, the complex metal cyanide catalyst is less likely to deactivate and can easily maintain a highly active state. As a result, ring-opening addition polymerization proceeds more easily.

[0023] The water content of the initiator can be controlled by dehydration. Vacuum dehydration is one example of a dehydration method.

[0024] The basicity of the initiator (hereinafter also referred to as "CPR") is preferably 10 or less, more preferably 3 or less, and even more preferably 1 or less. The lower limit of CPR is not particularly limited, but may be 0.01 or higher, or 0.1 or higher. CPR refers to the amount of basic substance contained in the initiator, as defined in "Part 4: Method for determining basicity" of JIS K 1557-3:2007, and specifically represents the microequivalent value of the basic substance in 30 g of the initiator to be measured. Furthermore, if the initiator's pH is basic, the above pH is determined by the strength of the basic substance and the amount of basic substance it contains (i.e., CPR). According to the inventors' research, it was found that lowering the CPR of the initiator further facilitates ring-opening addition polymerization. Specifically, it was found that by setting the CPR of the initiator to an appropriate value, the complex metal cyanide catalyst is less likely to deactivate and can maintain a highly active state. When the CPR is below the above upper limit, the complex metal cyanide catalyst is less likely to deactivate and can easily maintain a highly active state. As a result, ring-opening addition polymerization proceeds more easily.

[0025] The CPR of the initiator can be adjusted by adding an inorganic acid as needed. The inorganic acids described in the section on pH adjustment can be used.

[0026] As the active hydrogen-containing compound included in the initiator, compounds having a hydroxyl group bonded to a carbon atom are preferred. Examples of such compounds include monohydric alcohols such as 2-propanol, n-butanol, iso-butanol, 2-ethylhexanol, decyl alcohol, lauryl alcohol, tridecanol, cetyl alcohol, stearyl alcohol, and oleyl alcohol; dihydric alcohols such as diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,6-hexanediol, 1,4-cyclohexanediol, polyethylene glycol, polypropylene glycol, and polycarbonatediol; trihydric or higher polyhydric alcohols such as diglycerin; and phenols such as bisphenol A, bisphenol F, bisphenol S, novolac, resol, and resorcinol. These compounds can be used individually or in combination of two or more. Alternatively, low molecular weight compounds obtained by ring-opening addition polymerization of alkylene oxide to the above compounds or compounds with a molecular weight of less than 50 per active hydrogen may also be used. Examples of compounds with a molecular weight of less than 50 per active hydrogen include methanol, ethanol, water, ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, glucose, sorbitol, dextrose, fructose, sucrose, sugars such as methyl glucoside, or their derivatives. In the case of low molecular weight compounds obtained by ring-opening addition polymerization of alkylene oxide to compounds with a molecular weight of less than 50 per active hydrogen, a basic catalyst such as potassium hydroxide is used in the ring-opening addition polymerization. In this case, the basic catalyst is usually removed from the obtained low molecular weight compound, but a small amount of the basic catalyst may remain. Therefore, it is preferable to adjust the pH by adding an acid to the low molecular weight compound.

[0027] Preferably, at least one of the active hydrogen-containing groups in a compound having an active hydrogen-containing group is bonded to a secondary or tertiary carbon. Compounds having an active hydrogen-containing group preferably have etheric oxygen. Compounds containing active hydrogen groups may be used individually or in combination of two or more.

[0028] The content of the compound having an active hydrogen group relative to the total mass of the initiator is preferably 99.0% by mass or more, more preferably 99.2% by mass or more, and even more preferably 99.5% by mass or more. If it is above the lower limit of the above, ring-opening addition polymerization proceeds easily.

[0029] (Composite metal cyanide complex catalyst) A complex metal cyanide catalyst (hereinafter also referred to as "DMC catalyst") is a ring-opening polymerization catalyst. The DMC catalyst contains the reaction product of a metal halide salt and a cyanide transition metal compound, ligands, and crystal water (coordinating water, etc.) encapsulated in the crystal. In addition, it may contain trace amounts of impurities that are unavoidable during manufacturing and water other than crystal water, which are present in the above-mentioned metal salt and metal compound.

[0030] Examples of cation-forming metals (metals contained in cyanide transition metal compounds) and metals in metal halide salts include zinc, iron, cobalt, nickel, aluminum, strontium, manganese, chromium, copper, tin, lead, molybdenum, and tungsten, with zinc, iron, cobalt, and nickel being preferred, and zinc being more preferred.

[0031] Examples of halogens in metal halide salts include fluorine, chlorine, bromine, and chlorine, with chlorine being preferred.

[0032] Examples of metals in cyanide transition metal compounds include cobalt, iron, chromium, manganese, and vanadium, with cobalt, iron, chromium, and manganese being preferred, and cobalt being more preferred.

[0033] Examples of the ligand include alcohol, ether, ester, aldehyde, ketone, amide, nitrile, sulfide, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and polyoxyalkylene poly(or mono)ol. Examples of the alcohol include tert-butyl alcohol, n-butyl alcohol, sec-butyl alcohol, iso-butyl alcohol, tert-pentyl alcohol, iso-pentyl alcohol, and ethylene glycol mono-tert-butyl ether. Examples of the polyoxyalkylene poly(or mono)ol include polypropylene diol. The ligand is preferably alcohol, and more preferably tert-butyl alcohol. The ligand may be used alone or in combination of two or more.

[0034] As the DMC catalyst, a zinc hexacyanocobaltate (Zn3[Co(CN)6]2) complex with tert-butyl alcohol as the ligand is preferred. Water and zinc chloride may be coordinated to the complex.

[0035] The DMC catalyst is considered to be represented by the following formula 1A. M f , 1 , 1 , b , , 1 , a , e , ,

[0036] , 1 , e , c , 2 , , 1 , 2 , f a [M<00000​​​​​​​​​​​​​​​​​​​​​​​​​​Examples include Zn(II), Fe(II), Fe(III), Co(II), Ni(II), Al(III), Sr(II), Mn(II), Cr(III), Cu(II), Sn(II), Pb(II), Mo(IV), Mo(VI), W(IV), and W(VI). The above M 2 Examples include Co(III), Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), V(IV), and V(V). Examples of X above include Cl, Br, and I. M 1 e X f The metal halide salt is preferably one or more selected from zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc sulfate, zinc nitrate, and zinc acetate. 2 It is more preferable to include one or more selected from zinc chloride and zinc bromide in terms of the interatomic distance between X and X.

[0037] Furthermore, in the method for producing a DMC catalyst, a slurry-like DMC catalyst mixture in which the DMC catalyst is dispersed in the polyether compound can also be prepared by mixing a polyether compound with a solution in which the solid component is dispersed in an aqueous solution of organic ligands, before filtering and separating the cake, and then distilling off water and excess organic ligands from the resulting mixture.

[0038] There are no particular restrictions on the amount of DMC catalyst used, but from the viewpoint of narrowing the molecular weight distribution, it is preferably 5 to 500 ppm by mass, more preferably 10 to 400 ppm by mass, and even more preferably 20 to 300 ppm by mass, relative to the total mass of the hydroxyl group-containing oxyalkylene polymer produced. In one embodiment, however, the amount of DMC catalyst used is preferably 200 ppm by mass or less, relative to the total mass of the hydroxyl group-containing oxyalkylene polymer produced. If the amount of complex metal cyanide catalyst used is above the lower limit mentioned above, ring-opening addition polymerization is more likely to proceed. By controlling the pH of the initiator to an appropriate range, ring-opening addition polymerization can proceed even if the amount of complex metal cyanide catalyst used is above the lower limit mentioned above.

[0039] (Alkylene oxide) The alkylene oxide is not particularly limited and is determined based on the application of the oxyalkylene polymer having a hydroxyl group. Examples of alkylene oxides include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, methyl glycidyl ether, 2,3-epoxy-1-propanol, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, lauryl glycidyl ether, hexyl glycidyl ether, tetrahydrofuran, epichlorohydrin, styrene oxide, and cyclohexene oxide. Among these, ethylene oxide and propylene oxide are preferred, and propylene oxide is more preferred.

[0040] Alkylene oxides may be used individually or in combination of two or more. That is, one alkylene oxide may be used as an initiator for homopolymerization, or two or more alkylene oxides may be used as initiators for copolymerization. In the case of copolymerization, two or more alkylene oxide monomers may be used as initiators for block copolymerization or random copolymerization.

[0041] When the polyoxyalkylene chain of an oxyalkylene polymer having hydroxyl groups is a random copolymer chain consisting of propylene oxide-based units (hereinafter, monomer-based repeating units are simply referred to as "monomer units," for example, alkylene oxide monomer-based repeating units are referred to as "alkylene oxide units") and ethylene oxide units, a method is preferred in which a ring-opening addition polymerization of a mixture of propylene oxide and propylene oxide is performed in the presence of a complex metal cyanide catalyst to obtain an oxyalkylene polymer having hydroxyl groups.

[0042] (Reaction conditions) Ring-opening addition polymerization can be carried out in a continuous or batch manner. Batch polymerization is preferred. In the batch method, an initiator and a complex metal cyanide catalyst are charged into the reactor, and alkylene oxide is supplied to produce an oxyalkylene polymer having a hydroxyl group.

[0043] If the pH of the initiator added to the reactor is outside the range of 4.0 to 8.0, an inorganic acid or inorganic base is added to adjust the pH to 4.0 to 8.0. If the CPR of the initiator charged into the reactor is not 10 or less, it is preferable to add an inorganic acid to adjust the CPR to 10 or less. If the moisture content of the initiator charged into the reactor is not 0.01% by mass, it is preferable to perform a dehydration treatment to adjust the moisture content to 0.01% by mass or less.

[0044] The reaction temperature, reaction time, and reactor pressure for ring-opening addition polymerization can be those known conditions. The reaction temperature may be, for example, 80-150°C or 90-140°C. The reaction time may be, for example, 3 to 30 hours, or 5 to 20 hours. The reactor pressure may be, for example, 0.01 to 0.90 MPaG, or 0.03 to 0.70 MPaG. It is preferable to supply the alkylene oxide to the reactor at a rate that maintains the above reaction temperature. The reaction atmosphere should preferably be one that is less susceptible to moisture contamination, and an inert gas atmosphere such as nitrogen is more preferable.

[0045] (Oxyalkylene polymer containing hydroxyl groups) Oxyalkylene polymers having hydroxyl groups consist of a main chain and terminal groups. The main chain of an oxyalkylene polymer having hydroxyl groups is a polymerization chain consisting of residues obtained by removing active hydrogen from an initiator and polyoxyalkylene chains containing alkylene oxide units. The terminal groups of an oxyalkylene polymer having hydroxyl groups are hydroxyl groups. Preferably, the polyoxyalkylene chain consists only of alkylene oxide units. If the polyoxyalkylene chain is a polyoxyalkylene chain having two or more types of alkylene oxide units, these alkylene oxide units may form block polymers or random polymers.

[0046] The alkylene oxide unit is a unit corresponding to the alkylene oxide described above. Examples of alkylene oxide units include ethylene oxide units, propylene oxide units, tetramethylene oxide units, and butylene oxide units, with ethylene oxide units and propylene oxide units being more preferred, and propylene oxide units being even more preferred. In other words, as polyoxyalkylene chains, polyoxypropylene chains consisting of propylene oxide units, polyoxyethylene-polyoxypropylene chains consisting of ethylene oxide units and propylene oxide units, and polyoxyethylene chains consisting of ethylene oxide units are preferred, with polyoxypropylene chains being more preferred.

[0047] The molecular weight in terms of hydroxyl value of the hydroxyalkylene polymer having hydroxyl groups is preferably 300 or more, more preferably 500 or more, and even more preferably 1000 or more. The upper limit of the molecular weight in terms of hydroxyl value is not particularly limited and is set based on the application of the hydroxyalkylene polymer having hydroxyl groups, but for example it may be 50,000 or less, or 20,000 or less. According to the method for producing the hydroxyalkylene polymer having hydroxyl groups of this embodiment, even if the molecular weight per active hydrogen of the initiator is small, it is possible to produce a hydroxyalkylene polymer having hydroxyl groups with a molecular weight in terms of hydroxyl value of hydroxyl groups equal to or greater than the lower limit using a complex metal cyanide catalyst.

[0048] The Mw / Mn ratio of the hydroxyl group-containing oxyalkylene polymer is not particularly limited, but from the viewpoint of handling viscosity, it is preferably 1.50 or less, more preferably 1.30 or less, and even more preferably 1.20 or less. The lower limit of Mw / Mn is not particularly limited and is set based on the application of the hydroxyl group-containing oxyalkylene polymer. If the Mw / Mn ratio is below the above upper limit, it can be determined that the ring-opening addition polymerization proceeded with the complex metal cyanide catalyst in a highly active state.

[0049] (Mechanism of action) As mentioned above, it was previously known that when the molecular weight of the active hydrogen-containing compound in the initiator is small, ring-opening addition polymerization is difficult to proceed with in complex metal cyanide catalysts. On the other hand, it was found that adjusting the pH of the initiator to between 4.0 and 8.0 facilitates the above-mentioned ring-opening addition polymerization. From these results, it was considered that when the pH of the initiator is below 4.0 or above 8.0, the complex metal cyanide catalyst is deactivated by the basic and acidic substances contained in the initiator. Furthermore, it was found that the above-mentioned ring-opening addition polymerization can be further promoted by adjusting the water content and CPR of the initiator. When the water content of the initiator is high, it was considered that the complex metal cyanide catalyst is deactivated by the water contained in the initiator. Also, when the CPR of the initiator is high, it was considered that the complex metal cyanide catalyst is deactivated by the basic substances contained in the initiator. [Examples]

[0050] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. Examples 1-4 and 7-19 are examples, and Examples 5-6 and 20-21 are comparative examples.

[0051] <Measurement method> (Hydroxyl value) The hydroxyl values ​​of compounds containing active hydrogen groups and oxyalkylene polymers containing hydroxyl groups contained in the initiator were measured in accordance with Method B (phthalation method) described in JIS K 1557-1:2007.

[0052] (Molecular weight based on hydroxyl value) The hydroxyl value-based molecular weight of compounds containing active hydrogen groups and oxyalkylene polymers containing hydroxyl groups contained in the initiator was calculated as 56,100 × number of active hydrogens / hydroxyl value.

[0053] (pH) The pH of the initiator was measured in accordance with JIS K 1557-3:2007, "Part 5: Method for determining color number, viscosity, acid value and pH." The pH of the initiator was measured after it had been initially charged into the reactor.

[0054] (Basicity) The basicity of the initiator was denoted as CPR and measured in accordance with "Part 4: Method for Determining Basicity" of JIS K 1557-3:2007. The basicity of the initiator was measured after the initiator had been charged into the reactor.

[0055] (moisture content) The moisture content of the initiator was measured in accordance with "Part 2: Method for determining moisture content" of JIS K 1557-2:2007.

[0056] (Mw / Mn) The molecular weight distribution (Mw / Mn) of hydroxyl group-containing oxyalkylene polymers was calculated using the number-average molecular weight (Mn) and mass-average molecular weight (Mw) in polystyrene equivalent, measured using a calibration curve prepared with standard polystyrene samples of known molecular weight, and a gel permeation chromatograph analyzer HLC-8420GPC (Tosoh Corporation product name). A TSKgel SupermultiporeHZ-M (Tosoh Corporation product name) column was used, and tetrahydrofuran was used as the solvent. The sample pump was set to a flow rate of 0.350 mL / min, and the reference pump was also set to a flow rate of 0.350 mL / min.

[0057] (viscosity) The viscosity of oxyalkylene polymers containing hydroxyl groups was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: TV-100EH) at a measurement temperature of 25°C.

[0058] <Preparation of zinc hexacyanocobaltate catalyst> A zinc hexacyanocobaltate catalyst (hereinafter also referred to as "DMC catalyst") obtained by the method described in Example 3 of Japanese Patent Publication No. 2003-190808 was used. Specifically, a reaction solution obtained by reacting zinc chloride with K3[Co(CN)6] was mixed with 80 g of tert-butyl alcohol, 1 g of polyoxypropylene glycol (also called "PPG1") with a hydroxyl value of 75 mg KOH / g and 2 hydroxyl groups, and 80 g of water, and the mixture was heated to 60°C. After stirring for 1 hour, filtration (first filtration) was performed to obtain a cake containing the DMC catalyst organic phase. Next, a mixture of 40 g of tert-butyl alcohol, 1 g of "PPG1", and 70 g of water was added to this cake containing the DMC catalyst organic phase, stirred for 30 minutes, and then filtered (second filtration). To the cake containing the DMC catalyst organic phase obtained by this filtration, a mixture of 80 g of tert-butyl alcohol, 1 g of "PPG1", and 10 g of water was added, stirred, and filtered (third filtration). The cake containing the organic phase of the DMC catalyst obtained by this filtration operation was dried at 80°C until there was no change in mass, and then pulverized to obtain a powdered DMC catalyst.

[0059] [Example 1] 1618 g of an initiator containing polypropylene glycol with a molecular weight equivalent to 400 hydroxyl groups was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration treatment was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. The temperature was then lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.32 g of DMC catalyst was charged. The amount of DMC catalyst used was 40 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C, and the mixture was mixed for 1 hour under reduced pressure of -0.1 MPaG and stirring at 200 rpm. The internal pressure of the reactor was then reduced to 0.01 MPaG using nitrogen gas while maintaining the internal temperature at 130°C. Subsequently, 157 g of propylene oxide was supplied at 130°C for initial activation. After 13 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 5254 g of propylene oxide was supplied over 3 hours at 130°C. After a 1-hour maturation period at 130°C, the reactor pressure was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Subsequently, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer containing hydroxyl groups as the product. Table 1 shows the properties of the initiator, the amount of catalyst used, whether or not dehydration treatment was performed, the time until a decrease in internal pressure was confirmed (indicated as "time until reaction initiation" in Table 1), the hydroxyl value-based molecular weight of the target hydroxyl group-containing oxyalkylene polymer, and the properties of the hydroxyl group-containing oxyalkylene polymer (the same applies to Examples 2-21 below).

[0060] [Examples 2-6] The reaction was carried out in the same manner as in Example 1, except that the properties of the initiator were changed to those described in Table 1. Note that in Examples 5-6, a [-] in "Time to reaction initiation" indicates that no decrease in internal pressure was observed, and therefore the reaction did not proceed. Phosphate was added as needed (the same applies to Examples 7-21). Note that phosphate was also added in Example 6, where the initiator pH was the highest.

[0061] [Example 7] The reaction was carried out in the same manner as in Example 1, except that the initiator was not subjected to vacuum dehydration and the DMC catalyst was not subjected to vacuum operation after being charged into the reactor. Specifically, 1618 g of polypropylene glycol with a hydroxyl value-based molecular weight of 400, which served as the initiator, was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and depressurization piping. After purging with nitrogen gas, the temperature was raised to 130°C, and the mixture was stirred at 200 rpm for 1 hour. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled. The pH, CPR, and water content of the initiator were measured. Next, 0.32 g of DMC catalyst was charged. The amount of DMC catalyst used was 40 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C, and the reactor pressure was reduced to 0.01 MPaG with nitrogen gas while maintaining the internal temperature at 130°C under stirring conditions of 200 rpm. Subsequently, 157 g of propylene oxide was supplied at 130°C for initial activation. After 66 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 5254 g of propylene oxide was supplied at 130°C over 3 hours. After a 1-hour maturation period at 130°C, the reactor was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Then, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer containing hydroxyl groups as the product.

[0062] [Example 8] The reaction was carried out in the same manner as in Example 1, except that the hydroxyl value-based molecular weight of the active hydrogen-containing compound included in the initiator was changed to be as shown in Table 1. Specifically, 1252 g of an initiator containing polypropylene glycol with a molecular weight equivalent to 300 hydroxyl groups was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.32 g of DMC catalyst was charged. The amount of DMC catalyst used was 40 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C, and the mixture was mixed for 1 hour under reduced pressure of -0.1 MPaG and stirring at 200 rpm. The internal pressure of the reactor was then reduced to 0.01 MPaG using nitrogen gas while maintaining the internal temperature at 130°C. Subsequently, 120 g of propylene oxide was supplied at 130°C for initial activation. After 18 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 6798 g of propylene oxide was supplied over 3 hours at 130°C. After a 1-hour maturation period at 130°C, the reactor pressure was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Subsequently, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer having hydroxyl groups as the product.

[0063] [Example 9] The reaction was carried out in the same manner as in Example 1, except that the hydroxyl value-based molecular weight of the active hydrogen-containing compound included in the initiator was changed to be as shown in Table 1. Specifically, 802 g of an initiator containing tripropylene glycol with a hydroxyl value-based molecular weight of 192 was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration treatment was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.32 g of DMC catalyst was charged. The amount of DMC catalyst used was 40 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C, and the mixture was mixed for 1 hour under reduced pressure of -0.1 MPaG and stirring at 200 rpm. The internal pressure of the reactor was then reduced to 0.01 MPaG using nitrogen gas while maintaining the internal temperature at 130°C. Subsequently, 75 g of propylene oxide was supplied at 130°C for initial activation. After 25 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 7248 g of propylene oxide was supplied over 3 hours at 130°C. After a 1-hour maturation period at 130°C, the reactor pressure was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Subsequently, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer containing hydroxyl groups as the product.

[0064] [Example 10] The reaction was carried out in the same manner as in Example 9, except that the properties of the initiator were changed to be described in Table 1.

[0065] [Example 11] The reaction was carried out in the same manner as in Example 1, except that the molecular weight of the active hydrogen-containing compound in the initiator (calculated on a hydroxyl value basis), the amount of catalyst used, and the molecular weight of the target oxyalkylene polymer (calculated on a hydroxyl value basis) were changed as shown in Table 1. Specifically, 1122 g of an initiator containing dipropylene glycol with a hydroxyl value-based molecular weight of 134 was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration treatment was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.80 g of DMC catalyst was charged. The amount of DMC catalyst used was 100 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C, and the mixture was mixed for 1 hour under reduced pressure of -0.1 MPaG and stirring at 200 rpm. The internal pressure of the reactor was then reduced to 0.01 MPaG using nitrogen gas while maintaining the internal temperature at 130°C. Subsequently, 107 g of propylene oxide was supplied at 130°C for initial activation. After 45 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 6928 g of propylene oxide was supplied over 3 hours at 130°C. After a 1-hour maturation period at 130°C, the reactor pressure was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Subsequently, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer having hydroxyl groups as the product.

[0066] [Example 12] The reaction was carried out in the same manner as in Example 11, except that the initiator was not subjected to vacuum dehydration and the DMC catalyst was not subjected to vacuum operation after being charged into the reactor.

[0067] [Example 13] After charging the DMC catalyst into the reactor, the reaction was carried out in the same manner as in Example 1, except that the vacuum operation was omitted and the type of active hydrogen-containing compound included in the initiator and the hydroxyl value-based molecular weight of the target oxyalkylene polymer were changed as shown in Table 1. Specifically, 2690g of an initiator containing polypropylene triol with a hydroxyl value-based molecular weight of 1000 was charged into a 10L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.32g of DMC catalyst was charged. The amount of DMC catalyst used was 40 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C and the reactor pressure was reduced to 0.01 MPaG with nitrogen gas while maintaining the internal temperature at 130°C and stirring conditions of 200 rpm. Subsequently, 264 g of propylene oxide was supplied at 130°C for initial activation. After 9 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 5360 g of propylene oxide was supplied at 130°C over 3 hours. After a 1-hour maturation period at 130°C, the reactor pressure was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Then, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer containing hydroxyl groups as the product.

[0068] [Example 14] The reaction was carried out in the same manner as in Example 13, except that the hydroxyl value-based molecular weight of the active hydrogen-containing compound included in the initiator was changed to be as shown in Table 1. Specifically, 1106 g of an initiator containing polypropylene triol with a hydroxyl value-based molecular weight of 400 was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.32 g of DMC catalyst was charged. The amount of DMC catalyst used was 40 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C and the reactor pressure was reduced to 0.01 MPaG with nitrogen gas while maintaining the internal temperature at 130°C and stirring conditions of 200 rpm. Subsequently, 106 g of propylene oxide was supplied at 130°C for initial activation. After 13 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 6944 g of propylene oxide was supplied at 130°C over 3 hours. After a 1-hour maturation period at 130°C, the reactor was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Then, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer containing hydroxyl groups as the product.

[0069] [Example 15] The reaction was carried out in the same manner as in Example 13, except that the molecular weight of the compound containing an active hydrogen group in the initiator (calculated on a hydroxyl value basis) and the amount of catalyst used were changed as shown in Table 1. Specifically, 842 g of an initiator containing polypropylene triol with a hydroxyl value-based molecular weight of 300 was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.32 g of DMC catalyst was charged. The amount of DMC catalyst used was 40 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer to be produced). After purging with nitrogen gas, the temperature was raised to 130°C and the reactor pressure was reduced to 0.01 MPaG with nitrogen gas while maintaining the internal temperature at 130°C and stirring conditions of 200 rpm. Subsequently, 79 g of propylene oxide was supplied at 130°C for initial activation. After 10 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 7208 g of propylene oxide was supplied at 130°C over 3 hours. After a 1-hour maturation period at 130°C, the reactor was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Then, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer containing hydroxyl groups as the product.

[0070] [Example 16] The reaction was carried out in the same manner as in Example 1, except that the type of compound containing an active hydrogen group in the initiator, the amount of catalyst used, and the hydroxyl value-based molecular weight of the target oxyalkylene polymer were changed as shown in Table 1. Specifically, 1860 g of an initiator containing polypropylene hexaol with a hydroxyl value-based molecular weight of 874 was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration treatment was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.80 g of DMC catalyst was charged. The amount of DMC catalyst used was 100 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C, and the mixture was mixed for 1 hour under reduced pressure of -0.1 MPaG and stirring at 200 rpm. The internal pressure of the reactor was then reduced to 0.01 MPaG with nitrogen gas while maintaining the internal temperature at 130°C. Subsequently, 181 g of propylene oxide was supplied at 130°C for initial activation. After 40 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 7208 g of propylene oxide was supplied over 3 hours at 130°C. After a 1-hour maturation period at 130°C, the reactor pressure was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Subsequently, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer having hydroxyl groups as the product.

[0071] [Examples 17-18] The reaction was carried out in the same manner as in Example 16, except that the properties of the initiator were changed to be described in Table 1.

[0072] [Example 19] The reaction was carried out in the same manner as in Example 1, except that the hydroxyl value-based molecular weight of the active hydrogen-containing compound included in the initiator was changed to be as shown in Table 1. Specifically, 2796 g of an initiator containing polypropylene glycol with a molecular weight equivalent to 700 hydroxyl groups was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration treatment was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.32 g of DMC catalyst was charged. The amount of DMC catalyst used was 40 ppm by mass relative to the total mass of the initiator and alkylene oxide (i.e., the total mass of the hydroxyl-containing oxyalkylene polymer produced). After purging with nitrogen gas, the temperature was raised to 130°C, and the mixture was mixed for 1 hour under reduced pressure of -0.1 MPaG and stirring at 200 rpm. The internal pressure of the reactor was then reduced to 0.01 MPaG using nitrogen gas while maintaining the internal temperature at 130°C. Subsequently, 275 g of propylene oxide was supplied at 130°C for initial activation. After 19 minutes, initial activation was confirmed due to a decrease in internal pressure, and then 5254 g of propylene oxide was supplied over 3 hours at 130°C. After a 1-hour maturation period at 130°C, the reactor pressure was reduced to -0.1 MPaG to confirm that there was no unreacted propylene oxide. Subsequently, 2.0 g of Irganox 1076 was added as an antioxidant to obtain an oxyalkylene polymer having hydroxyl groups as the product.

[0073] [Example 20] The reaction was carried out in the same manner as in Example 1, except that the molecular weight of the compound containing an active hydrogen group in the initiator (calculated on a hydroxyl value basis) and the amount of catalyst used were changed as shown in Table 1. Specifically, 658 g of an initiator containing propylene glycol with a hydroxyl value equivalent molecular weight of 76 was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration treatment was carried out for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.80 g of a DMC catalyst ligand was charged. The amount of DMC catalyst used was 100 ppm by mass relative to the total mass of the initiator and alkylene oxide. After purging with nitrogen gas, the temperature was raised to 130°C, and mixing treatment was carried out for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. The internal pressure of the reactor was reduced to 0.01 MPaG with nitrogen gas while maintaining the internal temperature of the reactor at 130°C. Subsequently, 61 g of propylene oxide was supplied at 130°C for initial activation. After 120 minutes, no decrease in internal pressure was observed, so the reaction was stopped.

[0074] [Example 21] The reaction was carried out in the same manner as in Example 1, except that the molecular weight of the compound containing an active hydrogen group in the initiator (calculated on a hydroxyl value basis) and the amount of catalyst used were changed as shown in Table 1. Specifically, 546 g of an initiator containing ethylene glycol with a hydroxyl value-based molecular weight of 62 was charged into a 10 L reactor equipped with a stirrer, impeller, heating jacket, cooling coil, nitrogen introduction piping, and vacuum piping. After purging with nitrogen gas, the temperature was raised to 130°C, and dehydration treatment was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. Then, the temperature was lowered to 80°C, and 50 g of the initiator in the reactor was sampled and its pH, CPR, and moisture content were measured. Next, 0.80 g of DMC catalyst was charged. The amount of DMC catalyst used was 100 ppm by mass relative to the total mass of the initiator and alkylene oxide. After purging with nitrogen gas, the temperature was raised to 130°C, and mixing treatment was performed for 1 hour under reduced pressure of -0.1 MPaG and stirring conditions of 200 rpm. The reactor temperature was maintained at 130°C, and the reactor pressure was reduced to 0.01 MPaG with nitrogen gas. Subsequently, 50 g of propylene oxide was supplied at 130°C for initial activation. After 120 minutes, no decrease in internal pressure was observed, so the reaction was stopped.

[0075] [Table 1]

[0076] [Table 2]

[0077] As shown in Examples 1-4 and 7-19, it was found that by setting the initiator pH to 4.0-8.0, ring-opening addition polymerization proceeded even when using initiators containing low molecular weight active hydrogen-containing groups with a molecular weight equivalent to 67-350 hydroxyl value per active hydrogen, catalyzed by the complex metal cyanide complex catalyst. Furthermore, although the amount of complex metal cyanide complex catalyst used relative to the total mass of the oxyalkylene polymers produced in Examples 1-4 and 7-19 was very small (40-100 ppm by mass), ring-opening addition polymerization proceeded. On the other hand, in Example 5, where the initiator containing the active hydrogen-containing group had a molecular weight equivalent to 400 hydroxyl value per active hydrogen, and the pH was 3.4, and in Example 6, where the pH was 8.1, ring-opening addition polymerization did not proceed. Also, even when the initiator pH was set to 4.0-8.0, ring-opening addition polymerization did not proceed in Examples 20 and 21, where initiators containing low molecular weight active hydrogen-containing groups with a molecular weight equivalent to 31-38 hydroxyl value per active hydrogen were used. In other words, in Examples 1-4 and 7-19, while the complex metal cyanide catalyst was in a highly active state, alkylene oxide underwent ring-opening addition polymerization with an initiator containing a compound having an active hydrogen group, thereby producing an oxyalkylene polymer having a hydroxyl group.

[0078] Focusing on Examples 1-4 and 7, which used initiators containing compounds with active hydrogen-containing groups whose molecular weight per hydroxyl group is 200, it was observed that in Example 2, where the initiator pH was 4.6, the reaction time to initiation was longer and the Mw / Mn ratio tended to be higher compared to Example 1, where the initiator pH was 7.0, and Example 3, where the initiator pH was 5.0. In Example 4, where the initiator pH was 7.4, the reaction time to initiation tended to be longer compared to Example 1, where the initiator pH was 7.0, and Example 3, where the initiator pH was 5.0. Furthermore, in Example 7, where the initiator water content was 0.039% by mass, the reaction time to initiation was longer and the Mw / Mn ratio tended to be higher compared to Example 1, where the initiator water content was 0.0014% by mass.

[0079] Focusing on Examples 16-18, which used initiators containing compounds with active hydrogen-containing groups whose hydroxyl value-based molecular weight per active hydrogen is 146, a tendency for Mw / Mn to be larger was observed in Example 17, where the initiator's CPR was 6.9, compared to Example 16, where the initiator's CPR was 2.2. Furthermore, in Example 18, where the initiator's CPR was even higher at 16.0, the time to reaction initiation was longer, and ring-opening addition polymerization did not proceed to the target molecular weight.

Claims

1. A method for producing an oxyalkylene polymer having a hydroxyl group, comprising ring-opening addition polymerization of an alkylene oxide to an initiator containing a compound having an active hydrogen group (excluding α-hydroxy-ω-hydroxypoly(oxybutane-1,4-diyl), pentane-1,5-diol, and decane-1,10-diol) in the presence of a complex metal cyanide catalyst, The molecular weight per active hydrogen of the compound having the active hydrogen-containing group is 50 or more. A method for producing an oxyalkylene polymer having a hydroxyl group, wherein the pH of the initiator is 4.0 or higher and 8.0 or lower.

2. A method for producing an oxyalkylene polymer having a hydroxyl group according to claim 1, wherein the molecular weight per active hydrogen of the compound having the active hydrogen group is 400 or less.

3. A method for producing an oxyalkylene polymer having a hydroxyl group according to claim 1 or 2, wherein the water content relative to the total mass of the initiator is 0.01% by mass or less.

4. A method for producing an oxyalkylene polymer having a hydroxyl group according to claim 1 or 2, wherein the basicity (CPR) of the initiator is 10 or less.

5. A method for producing an oxyalkylene polymer having hydroxyl groups according to claim 1 or 2, wherein the amount of a complex metal cyanide catalyst used relative to the total mass of the oxyalkylene polymer having hydroxyl groups is 200 ppm by mass or less.

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