JP5874285B2 - Process for producing polyalkylene glycol - Google Patents

Description

  The present invention relates to a method for producing a polyalkylene glycol using an active species comprising an imino group-containing phosphazenium salt and an active hydrogen compound, and more specifically, an active species for producing a polyalkylene glycol comprising an imino group-containing phosphazenium salt. After the polymerization reaction of the alkylene oxide used, by treating with a solid acid, the polyalkylene glycol polymerization active species and / or the imino group-containing phosphazenium salt, which is a raw material thereof, is efficiently separated, thereby allowing the polymerization active species and / or its The present invention relates to a method for efficiently producing a polyalkylene glycol having a low residual amount of raw materials.

  Polyalkylene glycol is useful as a raw material for polyurethanes and surfactants, and is produced on an industrial scale. As a general production method thereof, there is known a method of addition polymerization of an alkylene oxide to a polyfunctional active hydrogen compound using potassium hydroxide (hereinafter sometimes referred to as KOH) as a catalyst. Consists of a polymerization step for producing a crude polyalkylene glycol by addition polymerization, and a purification step for adding salt to the crude polyalkylene glycol to neutralize KOH, followed by dehydration and drying to remove the deposited salt by filtration. is there.

  However, when a polyalkylene glycol is produced using a KOH catalyst, it is known that a monool having an unsaturated group at the terminal is produced as a by-product with an increase in the molecular weight of the polyalkylene glycol, and a large amount of the monool is contained. When polyalkylene glycol is used as a polyurethane raw material, the resulting polyurethane has low hardness and durability, and its use is limited.

  Therefore, various methods for producing a polyalkylene glycol having a high molecular weight and a small monool amount have been studied, and a method using a specific phosphazene compound as a catalyst has been proposed (for example, see Patent Document 1). When polyalkylene glycol is produced using this phosphazene compound as a catalyst, the productivity is greatly improved. On the other hand, this phosphazene compound is expensive and affects the urethanization reaction. In order to use the obtained polyalkylene glycol as a polyurethane raw material, it was necessary to remove the catalyst.

  The catalyst removal method at that time is 1) a method in which an acid compound is added to the crude polyalkylene glycol to neutralize the catalyst and then treated with an adsorbent, and 2) the crude polyalkylene glycol is washed with water, and then the aqueous phase is separated. 3) A method of adding water to the crude polyalkylene glycol and then bringing it into contact with an ion exchange resin, etc. (see, for example, Patent Document 2) has been proposed. Among them, for removing a phosphazene compound that is a large molecule, The use of a solid acid having a specific pore size and specific surface area as an adsorbent has been proposed (for example, see Patent Document 3). As a method for recovering the catalyst, a method of contacting a crude polyalkylene glycol with an acid compound and separating and recovering a phosphazenium compound precipitated after dehydration and drying has been proposed (for example, see Patent Document 4).

  On the other hand, a method of using an imino group-containing phosphazenium salt that is more compact and easier to synthesize than the phosphazene compound as a polyalkylene glycol production catalyst has been proposed (for example, see Patent Document 5).

Japanese Patent Laid-Open No. 10-77289 (see, for example, claims) Japanese Patent Laid-Open No. 11-106500 (for example, refer to the claims) JP 2001-106780 A (see, for example, the claims). Japanese Patent Laid-Open No. 10-330475 (see, for example, claims) Japanese Patent Laying-Open No. 2010-150514 (for example, refer to the claims)

  However, Patent Document 5 does not mention a method for separating and recovering the catalyst. Further, since the imino group-containing phosphazenium salt is basic, if it remains in the polyalkylene glycol, it may adversely affect the moldability and physical properties of the polyurethane. For these reasons, a method for producing polyalkylene glycol is desired which efficiently separates an imino group-containing phosphazenium salt from a crude polyalkylene glycol obtained by a polymerization reaction of alkylene oxide.

  Therefore, as a result of intensive studies to solve the above problems, the present inventors have determined that when a polyalkylene glycol is produced using an active species comprising an imino group-containing phosphazenium salt, a specific solid acid is added to the polyalkylene glycol after polymerization. It is found that the imino group-containing phosphazenium salt can be efficiently separated by mixing the polymerization active species and / or polyalkylene glycol with a low residual amount of the raw materials of the polymerization active species, and a method for efficiently producing the same. The present invention has been completed.

That is, this invention relates to the manufacturing method of the polyalkylene glycol characterized by including at least the following (A) process and (B) process.
(A) Process; The process of performing the polymerization reaction of alkylene oxide, after preparing the active seed | species for polyalkylene glycol manufacture with the imino group containing phosphazenium salt shown by following General formula (1), and an active hydrogen compound.

(1)
(Here, R ₁ and R ₂ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and R ₁ and R ₂ are bonded to each other to form a ring structure. R ₁ or R ₂ may be bonded to each other to form a ring structure, and X ⁻ represents a hydroxy anion, an alkoxy anion, a carboxy anion, an alkyl carboxy anion having 2 to 5 carbon atoms, or Represents hydrogen carbonate anion.)
(B) Process; The process of isolate | separating a solid acid, after contacting a solid acid with the polyalkylene glycol obtained by the (A) process.

  The present invention will be described in detail below.

  The step (A) is a step of producing a polyalkylene glycol by conducting a polymerization reaction of an alkylene oxide. The active species for producing polyalkylene glycol at that time is prepared from an imino group-containing phosphazenium salt represented by the above general formula (1) and an active hydrogen-containing compound.

In the imino group-containing phosphazenium salt represented by the general formula (1), R ₁ and R ₂ are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and constitute R ₁ and R ₂ . Examples of the hydrocarbon group having 1 to 20 carbon atoms include methyl group, ethyl group, vinyl group, n-propyl group, isopropyl group, cyclopropyl group, allyl group, n-butyl group, isobutyl group, t-butyl group, Cyclobutyl group, n-pentyl group, neopentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, phenyl group, heptyl group, cycloheptyl group, octyl group, cyclooctyl group, nonyl group, cyclononyl group, decyl group, cyclodecyl group , Undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octyl Decyl group, can be exemplified nonadecyl group, and the like. R ₁ and R ₂ may be bonded to each other to form a ring structure. When R ₁ and R ₂ are bonded to each other to form a ring structure, for example, pyrrolidinyl group, pyrrolyl group, piperidinyl group , Indolyl group, isoindolyl group and the like. Furthermore, R ₁ or R ₂ may be bonded to each other to form a ring structure, and R ₁ or R ₂ may be bonded to each other to form a ring structure. In the case where the substituents in the above form an alkylene group such as an ethylene group, a propylene group, and a butylene group, and the other substituents are bonded to each other to form a ring structure. As R ₁ and R ₂ , a methyl group, an ethyl group, and an isopropyl group are preferable because guanidines as raw materials are easily available.

In the imino group-containing phosphazenium salt represented by the general formula (1), X ⁻ represents a hydroxy anion, an alkoxy anion, a carboxy anion, an alkyl carboxy anion having 2 to 5 carbon atoms, or a hydrogen carbonate anion, and constitutes X ⁻ . Examples of the alkoxy anion include a methoxy anion, an ethoxy anion, an n-propoxy anion, an isopropoxy anion, an n-butoxy anion, an isobutoxy anion, a t-butoxy anion, and the like. For example, acetoxy anion, ethyl carboxy anion, n-propyl carboxy anion, isopropyl carboxy anion, n-butyl carboxy anion, isobutyl carboxy anion, t-butyl carboxy anion And the like. Among them, strong basic of the imino group-containing phosphazenium salt, since the polyalkylene glycol producing active species of the polymerization activity obtained is high, X ^- as a hydroxy anion are preferred.

  The imino group-containing phosphazenium salt represented by the general formula (1) can be obtained by any method, for example, imino group-containing phosphazenium chloride salt, imino group-containing phosphazenium iodide salt or imino group-containing phosphazenium. Examples of the method include ion exchange of a bromide salt using a basic compound or an ion exchange resin. Examples of the basic compound include alkali metal or alkaline earth metal hydroxide, alkali metal or alkaline earth metal. Alkoxides, alkali metal salts or alkaline earth metal salts of carboxylic acids, alkali metal or alkaline earth metal hydrogen carbonates, and the like can be mentioned. Among them, they are easily available, have strong basicity, and facilitate ion exchange. Therefore, an alkali metal or alkaline earth metal hydroxide is preferable, Sodium oxide, potassium hydroxide is particularly preferred.

  In addition, as a method for producing an imino group-containing phosphazenium chloride salt, an imino group-containing phosphazenium bromide salt or an imino group-containing phosphazenium iodide salt, for example, phosphorus pentachloride and a guanidine represented by the following general formula (2) are used. The method of reacting can be mentioned.

(2)
(Wherein, _{R 1} and _{R 2} are the same definition as _{R 1} and _{R 2} in formula (1).)
Examples of the imino group-containing phosphazenium salt represented by the general formula (1) include tetrakis (tetramethylguanidino) phosphazenium hydroxide, tetrakis (tetramethylguanidino) phosphazenium methoxide, tetrakis (tetramethylguanidino). ) Phosphazenium ethoxide, tetrakis (tetramethylguanidino) phosphazenium carboxyoxide, tetrakis (tetraethylguanidino) phosphazenium hydroxide, tetrakis (tetraethylguanidino) phosphazenium methoxide, tetrakis (tetraethylguanidino) Examples thereof include phosphazenium ethoxide and tetrakis (tetraethylguanidino) phosphazenium carboxyoxide. Among them, they can be easily produced, and are used in the polymerization reaction of alkylene oxide. Because it can provide an active species having high activity Te, tetrakis (tetramethylguanidino) phosphazenium hydroxide are preferred.

  In the step (A), the active hydrogen-containing compound used when preparing the active species for producing the polyalkylene glycol may be any compound having an active hydrogen group in the molecule. An acid compound, a phenol compound, a thiol compound, etc. can be mentioned, More specifically, for example, water, ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4- Hydroxy compounds such as butanediol, 1,6-hexanediol, glycerin, trimethylolpropane, hexanetriol, pentaerythritol, diglycerin, sorbitol, sucrose, glucose; ethylenediamine, N, N′-dimethylethylenediamine, Perijin, amine compounds such as piperazine; benzoic acid, carboxylic acid compounds such as adipic acid; 2-naphthol, phenol compounds such as bisphenol; ethanedithiol, can be exemplified thiol compounds such as butane dithiol. These can be appropriately selected according to the application. For example, when producing polyalkylene glycol for rigid foam, it is preferable to use, for example, pentaerythritol, sorbitol, sucrose, ethylenediamine, etc., and when producing polyalkylene glycol for flexible foam, for example, glycerin, Trimethylolpropane or the like is preferably used.

  Moreover, it is also possible to use the polyalkylene glycol which has a hydroxyl group as an active hydrogen containing compound, for example, polypropylene glycol, polypropylene glycol glycerol ether, etc. can be mentioned. The molecular weight of the polyalkylene glycol used in this case is not particularly limited, and among these, it is desirable that the polyalkylene glycol has a low viscosity, excellent fluidity, and easy handling.

  These active hydrogen-containing compounds may be used alone or in combination of several kinds.

In the step (A), the ratio of the imino group-containing phosphazenium salt represented by the general formula (1) and the active hydrogen-containing compound in preparing the active species for producing polyalkylene glycol is arbitrary, and among these, it is easier Since it becomes possible to produce a polyalkylene glycol having a high molecular weight, the imino group-containing phosphazenium salt represented by the general formula (1) 1 × 10 ⁻⁴ to 1 × 10 ⁻ per 1 mol of the active hydrogen compound. is preferably used in ¹ mole, preferably in the range of particularly 5 × ¹⁰ -3 ~5 × ^{10 -2} mol.

  In the step (A), the imino group-containing phosphazenium salt represented by the general formula (1) and the active hydrogen-containing compound are composed of an imino group-containing phosphazenium cation and an anion of the active hydrogen-containing compound. The active species for producing the polyalkylene glycol is prepared, and the preparation conditions at that time are arbitrary. In particular, since it is possible to prepare high-purity active species for producing polyalkylene glycol, it is desirable to efficiently remove the solvent and water as a by-product, particularly at 60 ° C. under reduced pressure of 1.3 kPa or less. It is preferable to prepare at the above temperature.

  Examples of the alkylene oxide used in the step (A) include epoxy compounds such as ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, and cyclohexene oxide. Among these, ethylene oxide, propylene oxide, 1,2-butylene oxide or styrene oxide is preferable, and ethylene oxide and propylene oxide are more preferable. Moreover, this alkylene oxide may be used independently and may use 2 or more types together. When two or more types of alkylene oxide are used in combination, the combined use of propylene oxide and ethylene oxide is particularly preferable. When propylene oxide and ethylene oxide are used in combination, for example, a method of simultaneously adding propylene oxide and ethylene oxide, a method of adding ethylene oxide next to propylene oxide, or a method of repeatedly adding propylene oxide, ethylene oxide and propylene oxide, etc. Can take. Among these, the method of adding ethylene oxide after the polymerization reaction of propylene oxide and further polymerizing is preferable.

  And the reaction temperature and reaction pressure in the case of the polymerization reaction of alkylene oxide in the step (A) can be arbitrarily set. Among these, from the viewpoint of polymerization efficiency and productivity, the reaction temperature is preferably in the range of 40 to 130 ° C, particularly preferably in the range of 80 to 120 ° C. Similarly, the reaction pressure is preferably 0.05 to 1.0 MPa, particularly preferably 0.1 to 0.6 MPa.

  A polyalkylene glycol can be obtained by the step (A). The polyalkylene glycol is a crude polyalkylene glycol, and an imino group-containing phosphazenium salt represented by the general formula (1), an active species for producing a polyalkylene glycol is selected. Contains a large amount.

In the step (B) of the present invention, the polyalkylene glycol obtained in the step (A) is contacted with a solid acid having an average particle size of 100 to 500 μm and a specific surface area of 100 m ² / g or more and less than 450 m ² / g, and then a solid. This is a step of separating the acid. That is, by contacting the polyalkylene glycol obtained in the step (A) with a solid acid, the imino group-containing phosphazenium salt and / or active species for producing the polyalkylene glycol remaining in the polyalkylene glycol are adsorbed to the solid acid. In this step, the solid acid is separated to obtain a polyalkylene glycol having a lower residual amount of the imino group-containing phosphazenium compound.

  Any solid acid may be used as long as it belongs to the category of solid acids, and examples thereof include synthetic aluminum silicate, synthetic magnesium silicate, activated clay, zeolite, and acid clay. Particularly preferred solid acids are aluminum silicate, magnesium silicate, and a mixture thereof. Among them, aluminum silicate is preferable because it is excellent in the ability to adsorb an imino group-containing phosphazenium salt and has high strength and is not easily crushed.

  The average particle size of the solid acid used is 100 to 500 μm. When the average particle size is less than 100 μm, it takes a long time to separate the solid acid by filtration, making it difficult to achieve efficient production. On the other hand, it is difficult to obtain a solid acid having an average particle size exceeding 500 μm.

The specific surface area of the solid acid used is less than 100 m ² / g or more 450 m ² / g. When the specific surface area is a solid acid of less than 100 m ² / g, the adsorption ability of the imino group-containing phosphazenium salt is poor, the adsorption process takes a long time, and a large amount of solid acid is required. It becomes a manufacturing method inferior in terms of surface. On the other hand, in the case of a solid acid having a specific surface area exceeding 450 m ² / g, the strength of the solid acid becomes poor, crushing occurs when the imino group-containing phosphazenium salt is adsorbed, and subsequent filtration and removal of the solid acid is difficult. This makes it difficult to achieve efficient production.

  Examples of the solid acid include aluminum silicate (trade name) KW-700-SN (manufactured by Kyowa Chemical Industry), (trade name) AD-700NS (manufactured by Tomita Pharmaceutical); magnesium silicate (trade name) KW. -600-SN (manufactured by Kyowa Chemical Industry Co., Ltd.), (trade name) AD-600NS (manufactured by Tomita Pharmaceutical) and the like can be obtained as commercial products.

  Here, there is no restriction | limiting in the usage-amount of this solid acid, and since an efficient process is attained among them, 0.1-3 weight part is preferable with respect to 100 weight part of polyalkylene glycol, and especially 0.5. It is preferable that it is -2 weight part.

  The method for contacting the polyalkylene glycol and the solid acid in the step (B) is arbitrary, and the temperature at that time is, for example, 60 to 110 ° C., preferably 70 to 100 ° C. In addition, examples of the contact time include 0.5 to 10 hours, preferably 1 to 3 hours.

  In contacting the polyalkylene glycol and the solid acid in the step (B), an aqueous medium may be allowed to coexist. In this case, the amount of the aqueous medium is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the polyalkylene glycol. When an aqueous medium is used, dehydration under reduced pressure may be performed after contacting the polyalkylene glycol and the solid acid, or dehydration under reduced pressure after the solid acid is separated. There is no restriction | limiting in particular in vacuum dehydration conditions at this time, For example, it can carry out at 80-120 degreeC and 0.01-5 kPa.

  In the step (B), the method for separating the polyalkylene glycol and the solid acid is arbitrary, and for example, methods such as vacuum filtration, pressure filtration, centrifugal filtration, decantation, and centrifugal decantation can be used. . In this case, a filter aid such as diatomaceous earth or cellulite can be used.

  The polyalkylene glycol obtained in the step (B) is a product obtained by separating the imino group-containing phosphazenium compound, but it can still be said to be a polyalkylene glycol containing some imino group-containing phosphazenium compound. The free imino group-containing phosphazenium compound referred to here is a compound derived from an active species for producing an imino group-containing phosphazenium salt and / or polyalkylene glycol contained in polyalkylene glycol, and is not necessarily represented by the above general formula (1). It does not correspond to the active species for producing imino group-containing phosphazenium salts and / or polyalkylene glycols shown.

  In the step (B), it is preferable that an antioxidant is present in order to suppress the generation of peroxides, aldehydes and the like when the polyalkylene glycol and the solid acid are brought into contact with each other. The addition amount is preferably 100 to 2000 ppm, particularly 600 to 1000 ppm, based on 100 parts by weight of the polyalkylene glycol. Examples of the antioxidant at that time include phenolic compound antioxidants, amine compound antioxidants, phosphite ester compound antioxidants, and the like. As the inhibitor, 2,6-di-tert-butyl-4-methylphenol (hereinafter sometimes abbreviated as BHT), 2-tert-butyl-4-methoxyphenol (hereinafter also abbreviated as BHA). 6) -tert-butyl-2,4-methylphenol, 2,6-di-tert-butylphenol, 2-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-ethyl Phenol and the like. Examples of amine compound antioxidants include n-butyl-p-aminophenol, 4,4-dimethyldiphenylamine, 4,4-dioctyldiphenylamine (hereinafter abbreviated as DOA), 4,4-bis-α, α. Examples include '-dimethylbenzylphenylamine. These antioxidants may be used alone or in combination of two or more. Among these antioxidants, BHT, BHA, and DOA are preferable.

  The method for producing a polyalkylene glycol according to the present invention includes the steps (A) and (B) described above, and any additional steps are included as long as they are performed through these steps without departing from the present invention. It is also possible.

  According to the production method of the present invention, it is possible to efficiently remove the imino group-containing phosphazenium compound, and it is possible to efficiently produce a polyalkylene glycol having a low residual amount of the imino group-containing phosphazenium compound. It becomes. The imino group-containing phosphazenium compound remaining in the polyalkylene glycol has a high possibility of adversely affecting the reaction with the polyisocyanate compound when used as a polyurethane material. Preferably, the polyalkylene glycol obtained by the production method of the present invention has a residual amount of the imino group-containing phosphazenium compound of 50 ppm or less, particularly 20 ppm or less, more preferably 10 ppm or less. It is preferable that

  Moreover, since the polyalkylene glycol obtained by the production method of the present invention reacts with a polyisocyanate compound to form a polyalkylene glycol which is less colored when made into a polyurethane and can be easily controlled, the pH is 5.5 to 8.0. The polyalkylene glycol is preferably used. In addition, pH as used here is measured as an apparent pH with a 2-propanol aqueous solution (2-propanol / water volume ratio = 100/60) at room temperature using, for example, a pH meter (saturated calomel electrode is a sleep type). Can do.

  Further, the polyalkylene glycol obtained by the production method of the present invention preferably has a hydroxyl value of 5 to 500 mgKOH / g, particularly 10 to 100 mgKOH / g, and more preferably 15 to 50 mgKOH / g. Further, the total unsaturation is preferably 0.05 meq./g or less, and in addition, the molecular weight distribution is preferably 1.1 or less. Moreover, such a polyalkylene glycol can be produced efficiently and easily.

  The polyalkylene glycol obtained by the method for producing polyalkylene glycol of the present invention is useful for polyurethane raw materials, polyester raw materials, surfactant raw materials, lubricant raw materials and the like. In particular, by reacting with various isocyanate compounds, rigid foam used for heat insulating materials, etc., flexible foam used for automobile seats / cushions, bedding, etc., adhesives, paints, sealing materials, thermosetting elastomers, heat Development to plastic elastomer is expected.

  According to the present invention, it has become possible to efficiently produce a polyalkylene glycol having excellent quality expected as a raw material for polyurethane and having a low residual amount of polymerization active species.

  Examples of the present invention will be shown below to clarify aspects of the present invention, but the present invention is not limited to these examples. In addition, the obtained polyalkylene glycol was evaluated by the method shown below.

~ Measurement of residual imino group-containing phosphazenium compounds in polyalkylene glycol ~
The obtained polyalkylene glycol was weighed into a volumetric flask, diluted with cyclohexanone, and then a trace total nitrogen analyzer (manufactured by Mitsubishi Chemical Corporation, (trade name) TN-100) was used, with heater temperature T1: 600 ° C, The nitrogen concentration (referred to as “c”) of the solution was measured under the conditions of T2: 800 ° C., gas flow rate O ₂ : 500 ml / min, O ₃ : 200 ml / min. From the nitrogen concentration at this time, the concentration of the imino group-containing phosphazenium compound in the solution was calculated from the following formula.

Residual amount of imino group-containing phosphazenium compound in polyalkylene glycol (% by weight) = c / 0.33
-PH measurement of polyalkylene glycol-
According to the measurement method described in JIS K 1557, the pH of the polyalkylene glycol was measured using a pH meter (saturated calomel electrode is a sleep type) and a 2-propanol aqueous solution at room temperature (2-propanol / water volume ratio = 100/60). The apparent pH at was measured.

-Measurement of hydroxyl value and total unsaturation of polyalkylene glycol-
It measured based on the measuring method of JISK1557.

-Measurement of specific surface area of solid acid-
The specific surface area is measured using a nitrogen adsorption specific surface area / pore distribution measuring device (trade name: ASAP2400, manufactured by Micromeritics) under conditions of liquid nitrogen temperature and nitrogen relative pressure of 0.001 to 0.995. went.

-Measurement of average particle size of solid acid-
Using a particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., trade name: Microtrac MT3000) and using diisopropyl ether as a dispersant, the cumulative curve of the particle size distribution expressed on a volume basis (median diameter; 50% of the cumulative curve) The diameter of a sphere having the same volume as that of the particles having a particle diameter corresponding to 1) was defined as the average particle diameter.

Synthesis Example 1 (Preparation of imino group-containing phosphazenium salt)
-Synthesis of imino group-containing phosphazenium chloride salts-
A 500 ml four-necked flask equipped with a stirring blade was placed in a nitrogen atmosphere, 11.5 g (55 mmol) of phosphorus pentachloride and 225 ml of toluene were added, and the mixture was stirred at -20 ° C. While maintaining the inside of the flask at −20 ° C., 65 g (550 mmol) of tetramethylguanidine was added dropwise, and stirring was continued at −20 ° C. for 1 hour. Furthermore, it heated up at 110 degreeC and stirred for 15 hours. The resulting white suspension was filtered to obtain a white solid as a filtrate. This white solid was dissolved in acetone and filtered to obtain a colorless transparent filtrate. The obtained filtrate was concentrated to obtain a target crude product of tetrakis (tetramethylguanidino) phosphazenium chloride as a white solid.

  The obtained crude product was subjected to liquid separation extraction with chloroform and water. The chloroform phase was concentrated to obtain 25.5 g (48.5 mmol; yield 88%) of the desired tetrakis (tetramethylguanidino) phosphazenium chloride as a white solid.

-Synthesis of imino group-containing phosphazenium salts-
Tetrakis (tetramethylguanidino) phosphazenium chloride 21 g (40 mmol) was added to a 300 ml Schlenk flask equipped with a magnetic rotator, and the inside of the flask was placed under a nitrogen atmosphere. Potassium hydroxide 2.2g (40mmol) and ethanol 80ml were added there, and it stirred at room temperature for 1 hour. The suspension containing the white solid obtained after completion of the reaction was filtered under reduced pressure using a funnel equipped with filter paper. The target tetrakis (tetramethylguanidino) phosphazenium hydroxide (imino group-containing phosphazenium salt in which R ₁ in the general formula (1) is a methyl group, R ₂ is a methyl group, and X ⁻ is a hydroxy anion on the filtrate side) ) Was obtained, and potassium chloride as a by-product salt was obtained on the filtrate side.

  To the resulting tetrakis (tetramethylguanidino) phosphazenium hydroxide-ethanol solution was added 80 ml of ion exchange water, the solvent was removed under reduced pressure, the solution was concentrated to 40 ml, and further 80 ml of ion exchange water was added. The solvent was removed, and the solution was concentrated to 40 ml to obtain an imino group-containing phosphazenium salt aqueous solution. The imino group-containing phosphazenium salt had a purity of 99.6% and an aqueous solution concentration of 50% by weight.

Example 1
(Process A)
In a 2 liter autoclave equipped with a stirring blade, 4.0 g of an imino group-containing phosphazenium salt aqueous solution (50 wt%; tetrakis (tetramethylguanidino) phosphazenium hydroxide) obtained in Synthesis Example 1 and an activated hydrogen compound 175 g (175 mmol) of trifunctional polyalkylene glycol (manufactured by Sanyo Chemical Industries, (trade name) Sannix GP-1000; hydroxyl value 160 mg KOH / g) was added, and the inside of the autoclave was placed in a nitrogen atmosphere, and the internal temperature was 80 ° C. Then, the solvent and by-product water were removed under a reduced pressure of 0.2 kPa to prepare an active species for producing polyalkylene glycol.

  Thereafter, the internal temperature was set to 90 ° C., and 880 g of propylene oxide was intermittently supplied so as to maintain the reaction pressure of 0.3 MPa or less, and the ring-opening polymerization reaction was performed for 8 hours while maintaining the internal temperature of 90 ° C. Next, after removing the residual propylene oxide under a reduced pressure of 0.2 kPa, 210 g of ethylene oxide was intermittently supplied so as to keep the reaction pressure at 0.4 MPa or less, and the internal temperature was maintained at 90 ° C. for 6 hours. A ring polymerization reaction was performed. The residual ethylene oxide was removed under a reduced pressure of 0.2 kPa to obtain 1200 g of a polypropylene glycol-polyethylene glycol block copolymer.

(Process B)
(A) Ion exchange water equivalent to 5 parts by weight with respect to 100 parts by weight of the polypropylene glycol-polyethylene glycol block copolymer obtained by the step, synthetic aluminum silicate as a solid acid (manufactured by Tomita Pharmaceutical Co., Ltd .: (trade name) ) AD-700SN) 2 parts by weight was added and stirred at 85 ° C. for 3 hours. Thereafter, dehydration was started while the temperature was increased and the pressure was reduced, and finally a vacuum dehydration operation was performed at 120 ° C. and 5 kPa for 3 hours. 60 g of the obtained copolymer slurry was put into a pressure filter having an effective filtration area of 12.5 cm ² equipped with a filter paper 5A (retained particle diameter: 7 μm) manufactured by ADVANTEC, and filtered at a pressure of 0.3 MPa. Then, the polypropylene glycol-polyethylene glycol block copolymer A was separated from the solid acid to produce a polypropylene glycol-polyethylene glycol block copolymer A. The time required for the separation was as short as 11 minutes and was excellent in production efficiency.

  The resulting polypropylene glycol-polyethylene glycol block copolymer A had a hydroxyl value of 24 mgKOH / g and an unsaturation of 0.021 meq. / G, the remaining amount of the imino group-containing phosphazenium compound was 6 ppm, pH 7.0. The results are shown in Table 1.

Examples 2-3
Polypropylene glycol in the same manner as in Example 1 except that the solid acid in Step (B) of Example 1 was changed as shown in Table 2 in terms of the solid acid species, the amount used, and the conditions shown in Table 1. -A polyethylene glycol block copolymer was produced. The results are shown in Table 2.

  The time required for separating the polypropylene glycol-polyethylene glycol block copolymer and the solid acid was short, and the production efficiency was excellent. Moreover, the obtained polypropylene glycol-polyethylene glycol block copolymer was excellent in quality.

Comparative Examples 1-3
Polypropylene glycol in the same manner as in Example 1 except that the solid acid in Step (B) of Example 1 was changed as shown in Table 2 in terms of the solid acid species, the amount used, and the conditions shown in Table 1. -A polyethylene glycol block copolymer was produced. The results are shown in Table 2.

  It took a long time to separate the polypropylene glycol-polyethylene glycol block copolymer and the solid acid, and the production efficiency was remarkably reduced.

  According to the production method of the present invention, the imino group-containing phosphazenium salt used as a catalyst can be efficiently removed, and the residual amount of the imino group-containing phosphazenium salt is low, and polyalkylene glycol having excellent pH characteristics can be efficiently supplied. Is possible. The obtained polyalkylene glycol is excellent in urethanization reactivity and can provide a polyurethane product excellent in quality, and its industrial applicability is extremely high.

Claims (5)

A method for producing a polyalkylene glycol, comprising at least the following steps (A) and (B).
(A) Process; The process of performing the polymerization reaction of alkylene oxide, after preparing the active seed | species for polyalkylene glycol manufacture with the imino group containing phosphazenium salt shown by following General formula (1), and an active hydrogen compound.

(1)
(Here, R ₁ and R ₂ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and R ₁ and R ₂ are bonded to each other to form a ring structure. R ₁ or R ₂ may be bonded to each other to form a ring structure, and X ⁻ represents a hydroxy anion, an alkoxy anion, a carboxy anion, an alkyl carboxy anion having 2 to 5 carbon atoms, or Represents hydrogen carbonate anion.)
(B) Step; After contacting the polyalkylene glycol obtained in Step (A) with a solid acid having an average particle size of 100 to 500 μm and a specific surface area of 100 m ² / g or more and less than 450 m ² / g, the solid acid is separated. Process. The polymerization reaction of alkylene oxide in the step (A) is a polymerization reaction of a polypropylene glycol-polyethylene glycol block copolymer in which ethylene oxide is further polymerized after the polymerization reaction of propylene oxide. A method for producing polyalkylene glycol. (B) In the process, aluminum silicate and / or magnesium silicate is used as a solid acid, The method for producing polyalkylene glycol according to claim 1 or 2. The method for producing a polyalkylene glycol according to any one of claims 1 to 3, wherein a polyalkylene glycol having an imino group-containing phosphazenium compound residual amount of 50 ppm or less and a pH of 5.5 to 8.0 is produced. The method for producing a polyalkylene glycol according to any one of claims 1 to 4, wherein a polyalkylene glycol having a hydroxyl value of 10 to 100 mgKOH / g and a total degree of unsaturation of 0.05 meq / g or less is produced.