JPH04185635A - Method for purifying polyoxyalkylene polyol - Google Patents

Abstract

PURPOSE:To improve quality and suppress side reactions in polyurethane manufacture by neutralizing a specific crude polyoxyalkylene polyol with a mineral acid, adding an adsorbent to the crude polyol in at least two stages, and carring out adsorption. CONSTITUTION:An alkylene oxide is addition-polymerized in the presence of an active hydrogen compd. and an alkaline catalyst to give a crude polyoxyalkylene polyol. After 0.05-30wt.% (based on the crude polyol) water is added to the crude polyol, it is neutralized to a pH of 4.5-7.5 with a mineral acid (e.g. phosphoric acid) and dehydrated by adding an adsorbent (e.g. a synthetic magnesium silicate) to the polyol, allowing the adsorbent to adsorb water at 50-150 deg.C, and separating the adsorbent from the polyol, thus giving a purified polyoxyalkylene polyol. In the above dehydration process, the adsorbent is divided into at least two portions is added to the crude polyol in at least two stages selected from the following stages: the stage before starting dehydration, the former-half stage of dehydration, the latter-half stage of dehydration and the stage after completing the dehydration.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a high-quality polyurethane that produces significantly fewer side reactions in reaction with isocyanate compounds than crude polyoxyalkylene polyols synthesized in the presence of alkaline catalysts. The present invention relates to a purification method for obtaining a polyoxyalkylene polyol.

[Conventional technology]

Polyoxyalkylene polyols are generally obtained by addition polymerizing alkylene oxide to active hydrogen compounds in the presence of an alkaline catalyst, and are widely used as raw materials for polyurethane, surfactants, cosmetic raw materials, etc. Although the polyoxyalkylene polyol produced by such a method contains an alkaline catalyst, it is desirable to remove it as much as possible because it has an adverse effect on the reaction with an isocyanate compound when making polyurethane.

As a purification method for removing alkaline catalysts from polyoxyalkylene polyols, there is a method in which after neutralization with acid, excess acid is adsorbed with an adsorbent such as synthetic magnesium silicate or synthetic aluminum silicate (Japanese Patent Publication No. 49-4839). , Japanese Patent Application Publication No. 54-312999, Japanese Patent Publication No. 57-2205
No. 5) is known.

In recent years, there has been a demand for polyoxyalkylene polyols that yield polyurethanes with fewer side reactions other than urethane reactions when reacting with isocyanate compounds. An alkylene polyol is obtained,
When the amount of adsorbent is large, it is difficult to completely remove the added adsorbent by a filtration operation, resulting in a cloudy polyoxyalkylene polyol.

[Problem to be solved by the invention]

The purpose of the present invention is to provide polyurethane with less side reactions other than urethane reaction in reaction with isocyanate compounds when adsorbing excess acid contained in polyoxyalkylene polyol neutralized with acid, and The object of the present invention is to provide a method for purifying polyoxyalkylene polyol that is useful for all uses as a urethane raw material and does not cause clouding due to insufficient removal.

Means for Solving Problem C] The present inventors have made extensive studies to solve the above problems, and as a result, have arrived at the present invention.

That is, in the present invention, when a crude polyoxyalkylene polyol synthesized in the presence of an alkaline catalyst is neutralized by adding a mineral acid and then purified by adsorption using an adsorbent, the adsorbent is charged in parts. This is a characteristic method for purifying polyoxyalkylene polyols.

The crude polyoxyalkylene polyol purified by the present invention is a normal polyoxyalkylene polyol obtained by addition polymerizing an alkylene oxide to an active hydrogen compound in the presence of an alkaline catalyst.

Active hydrogen compounds that can be used in the present invention include monohydric alcohols such as methanol, ethanol, butanol, octatool, lauryl alcohol, and stearyl alcohol;
Ethylene glycol, diethylene glycol, propylene gelcol, dipropylene glycol, dihydric alcohols such as 1,4-butanediol, glycerin, trimethylolpropane, diglycerin, pentaerythritol, sorbitol, cy! lI! polyhydric alcohols such as ethylenediamine, aliphatic amines such as diethylenetriamine, aromatic amines such as aniline, toluenediamine, 4,4゛-diaminodiphenylmethane, polyphenylpolymethylene polyamine, monoethanolamine, jetanolamine, triethanolamine Examples include alkanolamines such as phenol, phenol compounds such as bisphenol A, novolac resins, and the like. These active hydrogen compounds can be used alone or in combination of two or more.

Examples of alkaline catalysts that can be used in the present invention include potassium hydroxide, sodium hydroxide, potassium alcolade, sodium alcolade, potassium carbonate, sodium carbonate,
Examples include metallic potassium and metallic sodium.

Examples of the alkylene oxide that can be used in the present invention include ethylene oxide, propylene oxide, 1,2-butylene oxide, styrene oxide, allyl glycidyl ether, etc., and these can be used alone or in combination of two or more. .

The crude polyoxyalkylene polyol thus obtained contains an alkaline catalyst in an amount corresponding to the amount added, but usually in an amount of 0.05 to 1.0% by weight based on the target polyoxyalkylene polyol. be.

A preferred purification method of the present invention is to add 0.05 to 30% by weight of added water to the crude polyoxyalkylene polyol, further add mineral acid to adjust the pH to 4.5 to 7.5, and then heat the added water. When dehydration is removed by a reduced pressure operation, commercially available synthetic magnesium silicate is used as an adsorbent in an amount of 0.05 to 5% by weight based on the crude polyoxyalkylene polyol,
Adsorption treatment is carried out at 50 to 150°C, and the adsorbent is charged in at least two stages: before the start of the dehydration operation, during the first half of the dehydration operation, during the second half of the dehydration operation, and after the end of the dehydration operation. The purified polyoxyalkylene polyol is then obtained by filtration.

Mineral acids that can be used in the present invention include phosphoric acid, hydrochloric acid, sulfuric acid,
Examples include nitric acid and sulfite. The amount added is preferably such that the pH within the system is 4.5 to 7.5.

If the pH in the system exceeds 7.5, neutralization will be insufficient,
If the aPH is less than 4.5, at which the alkaline catalyst remains, a large amount of adsorbent is required and a large amount of cake is discharged, which is not preferable. Examples of the adsorbent that can be used in the present invention include synthetic magnesium silicate.

In the present invention, the amount of synthetic magnesium silicate used is:
0.05 to crude polyoxyalkylene polyol
Preferably, 5% by weight is used. More preferably 0.
It is 1 to 3% by weight. If it is less than 0.05% by weight, it is difficult to obtain an adsorption effect, and if it exceeds 5% by weight, sodium contained as an impurity in the adsorbent will elute into the polyoxyalkylene polyol, which is not preferable.

The adsorption treatment is preferably carried out at a temperature of 50 to 150°C, more preferably 70 to 120°C. If the temperature is lower than 50°C, the adsorption capacity of the adsorbent decreases, and if the temperature exceeds 150°C, the polyoxyalkylene polyol is denatured.

The salt purified by neutralization and the adsorbent are removed from the polyokine alkylene polyol by filtration.

〔Example〕

The present invention will be described below with reference to Examples and Comparative Examples.

Production of crude polyoxyalkylene polyol Production Example 1 37 g of glycerin and 3.6 g of potassium hydroxide were placed in a 21 autoclave, and after purging with nitrogen, it was heated to 120°C and dehydrated under reduced pressure (5+mmHg) for 2 hours. .

Next, 1170g of propylene oxide was added at a temperature of 120°C.
The reactor was gradually charged at a reaction pressure of 4 kg/cjG or less, and the reaction was carried out for 4 hours. The obtained crude polyokine alkylene polyol is referred to as polyol A.

Production Example 2 10 g of glycerin and 2.0 g of potassium hydroxide were placed in a 2N autoclave. After charging Og and purging with nitrogen, the reactor was heated to 320°C and dehydrated for 2 hours under reduced pressure (5 mdg). Next, 1040 g of propylene oxide was gradually charged at a temperature of 120°C and a reaction pressure of 4 kg/cdG or less, and the reaction was carried out for 4 hours.
℃ and reaction pressure of 4 kg/dG or less, the reaction was carried out for 2 hours. The obtained crude polyoxyalkylene polyol is referred to as polyol B.

Examples 1 to 7, Comparative Examples 1 to 4 1000 g of polyol A or B obtained in Production Example 1.2 was charged into a 2I four-bottle flask equipped with a stirrer, a thermometer, and a nitrogen inlet tube, and while blowing nitrogen Stir, 8
The temperature was raised to 0°C. Add water and mineral acid in the amounts shown in Table 1 at the same temperature, continue stirring for 30 minutes, and then check the pH. Next, add commercially available synthetic magnesium silicate as shown in Table 1. Then, adsorption and dehydration were carried out under reduced pressure at the temperatures shown in Table 1 for 4 hours. The generated salt and adsorbent were removed by filtration to obtain a purified polyoxyalkylene polyol. Furthermore, about 4.4゛-diphenylmethane diisocyanate was added to the obtained polyoxyalkylene polyol and the amount of hydroxyl groups in the polyoxyalkylene polyol.
．． 05 molar equivalents of dibutyltin dilaurate at 3 pph were charged into 11 separable flasks equipped with a stirrer, a thermometer, and a nitrogen inlet tube, and the reaction was carried out at 80°C. Results first
Shown in the table. In the reaction system in which a gelation reaction occurs in the reaction with the above-mentioned isocyanate compound, it can be considered that a side reaction occurs in addition to the urethane reaction.

As shown in the results of the examples shown in Table 1, the polyoxyalkylene polyol obtained by the purification method of the present invention has a colorless and transparent appearance and does not cause side reactions when reacting with isocyanate compounds, but the comparative example If the conditions of the present invention are not met as in the above, the appearance of the polyoxyalkylene polyol may become cloudy, or side reactions other than the urethane reaction may occur in the reaction with the isocyanate compound.

[Effects of the Invention] The polyoxyalkylene polyol purified by the method of the present invention has a colorless and transparent appearance, and upon reaction with an isocyanate compound, yields polyurethane with few side reactions other than urethane reactions, and can be used as a urethane raw material. useful for all applications.

Claims (1)

[Claims] 1. When crude polyoxyalkylene polyol synthesized in the presence of an alkaline catalyst is neutralized by adding a mineral acid and then purified by adsorption using an adsorbent, the adsorbent is charged in portions. A method for purifying polyoxyalkylene polyol, characterized by: 2. Before the start of the dehydration operation and during the dehydration operation when the adsorbent is dividedly charged to the crude polyoxyalkylene polyol by adding water and mineral acid to neutralize it and then dehydrating the added water by reducing the pressure. The method for purifying polyoxyalkylene polyol according to claim 1, characterized in that the adsorbent is charged in portions during at least two operation periods: the first half, the second half during the dehydration operation, and the operation period after the completion of the dehydration. .