JP2012140366A - Method of producing hindered polyol ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing polyol ester that has a high reaction velocity, does not need a moisture removal step, has a fully high reaction rate, and has a small acid value.SOLUTION: The method of producing the hindered polyol ester includes: a step 1 of adding 0.01-0.05 mass% of metal alkoxide based on the total mass of polyol and fatty acid lower alkyl ester to a mixed solution containing the fatty acid lower alkyl ester and the polyol having 150-1,000 mass ppm content of water and removing the moisture and generated lower alcohol in the system under a temperature of 60-90°C to make the content of water in the mixed solution to be 100 mass ppm or lower; and a step 2 of increasing the temperature to 160-250°C following the step 1 and maintaining the temperature in the above range.

Description

  The present invention relates to a method for producing a hindered polyol ester, and more particularly to a method for producing a hindered polyol full ester in which all hydroxyl groups of the polyol are esters.

  Hindered polyol esters, especially hindered polyol full esters in which all the hydroxyl groups of the polyol are esters, are excellent in lubricity, heat resistance, oxidation stability, low-temperature fluidity, biodegradability, etc. Used as base oil. This hindered polyol ester can be synthesized by an esterification reaction between a polyol and a fatty acid or a transesterification reaction between a polyol and a fatty acid lower alkyl ester. In the case of the transesterification reaction, a strong alkali such as sodium hydroxide, potassium hydroxide, or a metal alkoxide can be used as the catalyst. In particular, when an alkoxide such as sodium methoxide is used as the alkali catalyst, It is known that the reaction time can be shortened and a high reaction rate can be obtained as compared with the case where an alkali metal hydroxide such as sodium oxide is used (see Patent Document 1).

JP-A-7-305079

  The present inventors have found a new problem that when a metal alkoxide catalyst is used in a transesterification reaction, the acid value of a hindered polyol ester as a target product is increased due to the by-product of a fatty acid. This is presumably due to the fact that a fatty acid salt is produced by the reaction between a strongly alkaline metal alkoxide catalyst and a fatty acid ester, and this is hydrolyzed into a fatty acid in a washing step for removing the catalyst.

  On the other hand, when the amount of the alkali catalyst used is reduced in order to prevent the increase in the acid value, hindered polyol fullness by transesterification using hindered alcohol such as neopentyl glycol, trimethylolpropane, pentaerythritol as a polyol is used. In the production of esters, a decrease in reaction rate becomes a problem.

  Further, since the metal alkoxide catalyst reacts with water and decomposes and loses its catalytic activity, the water remaining in the raw material is problematic in that it reduces the productivity of the hindered polyol ester. On the other hand, including a step of removing moisture in the reaction system before the addition of the catalyst is problematic in that the production becomes complicated.

  Accordingly, an object of the present invention is to provide a method for producing a polyol ester, which can obtain a polyol ester having a high reaction rate, no need for a water removal step, a sufficiently high reaction rate, and a low acid value. To do.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies and as a result, obtained the following findings. That is, in a mixed solution containing the fatty acid lower alkyl ester having a water content of 150 mass ppm to 1,000 mass ppm and the polyol, the content of the polyol and the fatty acid lower alkyl ester is 0. The content of the moisture in the mixed solution is obtained by adding 01% by mass to 0.05% by mass of a metal alkoxide and distilling off the moisture in the system and the produced lower alcohol at a temperature of 60 ° C. to 90 ° C. The method for producing a hindered polyol ester, comprising: Step 1 in which the content is 100 ppm by mass or less; and Step 2 followed by Step 1 by heating to 160 ° C. to 250 ° C. and maintaining the temperature in the temperature range. It was found that a polyol ester having a high speed, no water removal step, a sufficiently high reaction rate, and a low acid value could be obtained, and the present invention was completed. It was.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A method for producing a hindered polyol ester by a transesterification reaction between a polyol and a fatty acid lower alkyl ester using a metal alkoxide as a catalyst, the hindered polyol ester comprising the following step 1 and the following step 2 It is a manufacturing method.
Step 1: In a mixed solution containing the fatty acid lower alkyl ester having a water content of 150 ppm to 1,000 ppm by mass and the polyol, 0 is added to the total mass of the polyol and the fatty acid lower alkyl ester. 0.01% by mass to 0.05% by mass of the metal alkoxide was added, and the water in the system and the lower alcohol produced were distilled off at a temperature of 60 ° C. to 90 ° C. to remove the water in the mixture. The process which makes content 100 mass ppm or less.
Process 2: The process of heating to 160 to 250 degreeC following the said process 1, and maintaining in this temperature range.
<2> The hinder according to <1>, wherein the ratio of the number of moles of fatty acid lower alkyl ester in step 1 / (number of moles of polyol × number of hydroxyl groups in one molecule of polyol) is 1.0 to 2.0. It is a manufacturing method of depolyol ester.
<3> The method according to any one of <1> to <2>, further including a step of distilling off an unreacted fatty acid lower alkyl ester and removing a metal alkoxide-derived component using an adsorbent after the step 2. It is a manufacturing method of hindered polyol ester.
<4> The method for producing a hindered polyol ester according to any one of <1> to <3>, wherein the polyol is trimethylolpropane.
<5> The method for producing a hindered polyol ester according to any one of <1> to <4>, wherein distillation of water and lower alcohol in step 1 is performed under a reduced pressure of 50 kPa or less.

  According to the present invention, the above-mentioned problems can be solved and the above-mentioned object can be achieved, the reaction rate is fast, the water removal step is unnecessary, the reaction rate is sufficiently high, and the acid value is small. The manufacturing method of the polyol ester which can obtain ester can be provided.

(Method for producing hindered polyol ester)
The method for producing a hindered polyol ester of the present invention includes a step 1 for performing a transesterification reaction under a relatively low temperature condition, and a step 2 for performing a transesterification reaction at a relatively high temperature after heating and raising the temperature. Further, it includes other steps as necessary.

<Step 1>
Step 1 is a step of performing a transesterification reaction under relatively low temperature conditions. In the step 1 (hereinafter sometimes referred to as “low temperature reaction step”), a metal alkoxide as a transesterification catalyst is added to and reacted with a mixed solution containing a polyol and a fatty acid lower alkyl ester. Water in the system and lower alcohol produced are distilled off.

<< Mixed liquid >>
The mixed solution contains at least a polyol and a fatty acid lower alkyl ester, and further contains other components as necessary.
When the transesterification reaction is performed using the polyol and the fatty acid alkyl ester as reaction raw materials and the metal alkoxide as a catalyst, if the reaction system contains moisture, the catalyst activity of the metal alkoxide is lost due to the moisture. However, such a reaction system usually contains about 150 mass ppm to 1,000 mass ppm of water derived from the raw material.
In the hindered polyol ester production method of the present invention, even in such a water-containing system, a water removal step is unnecessary, the reaction rate is fast, the reaction rate is sufficiently high, and the acid value is small. Is advantageous in that it can be obtained.

-Polyol (polyhydric alcohol)-
There is no restriction | limiting in particular as said polyol (polyhydric alcohol), According to the objective, it can select suitably, For example, hindered polyols, such as a trimethylol propane, a pentaerythritol, neopentyl glycol, are mentioned. These may be used alone or in combination of two or more.
Such hindered polyols are preferred in that the effects of the present invention can be obtained more effectively, especially when these full esters are produced, since it is usually difficult to obtain full esters due to steric hindrance. Among these, trimethylolpropane is preferable in that a pour point is low and a base material suitable for lubricating oil can be obtained.

  There is no restriction | limiting in particular as the preparation amount of the said polyol, According to the quantity of the said fatty-acid lower alkyl ester, etc., it can select suitably.

-Fatty acid lower alkyl ester-
The fatty acid lower alkyl ester is not particularly limited and may be appropriately selected depending on the intended purpose. The fatty acid lower alkyl ester having a saturated or unsaturated acyl group having 8 to 18 carbon atoms and 1 to 1 carbon atoms. No. 4 esters of lower alcohols are preferred, and fatty acid methyl esters are particularly preferred. These may be used alone or in combination of two or more.

  The fatty acid methyl ester is not particularly limited and may be appropriately selected depending on the intended purpose. For example, methyl caprylate, methyl caprate, methyl laurate, methyl myristate, methyl palmitate, methyl stearate, olein Examples include methyl acid.

There is no restriction | limiting in particular as an acid value of the said fatty-acid lower alkyl ester, Although it can select suitably according to the objective, Since the metal alkoxide which is an alkali catalyst is used for transesterification, it is so small that the said acid value is small A high reaction rate is obtained with a catalytic amount, and it is preferable because by-product fatty acids in the final product can be reduced, preferably 0.5 or less, more preferably 0.2 or less, and particularly preferably 0.1 or less. .
The acid value can be measured according to, for example, JIS K2501.

  The amount of the fatty acid lower alkyl ester charged is not particularly limited and may be appropriately selected depending on the intended purpose. From the viewpoint of efficiently obtaining a hindered polyol ester full ester, the number of moles of the fatty acid lower alkyl ester is / (Number of moles of the polyol x number of hydroxyl groups in one molecule of the polyol) is preferably in the range of 1.0 to 2.0, more preferably 1.05 to 1.5, and 1.1 to 1 .3 is particularly preferred.

<< metal alkoxide >>
There is no restriction | limiting in particular as a metal alkoxide as said transesterification catalyst, According to the objective, it can select suitably, For example, sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide etc. are mentioned. These may be used alone or in combination of two or more. Among these, sodium methoxide is preferable in terms of availability.

The addition amount of the metal alkoxide is not particularly limited as long as it is 0.01% by mass to 0.05% by mass with respect to the total mass of the polyol and the fatty acid lower alkyl ester, and is appropriately selected according to the purpose. However, it is preferably 0.01% by mass to 0.04% by mass, more preferably 0.01% by mass to 0.03% by mass with respect to the total mass of the polyol and the fatty acid lower alkyl ester. 0.01 mass% to 0.02 mass% is particularly preferable. When the addition amount is 0.01% by mass or more with respect to the total mass of the polyol and the fatty acid lower alkyl ester, a sufficient reaction rate is obtained, and when the addition amount is 0.05% by mass or less, Production can be suppressed, and a target product having a low acid value can be obtained. Moreover, when the addition amount is within the preferable range, it is advantageous in that a sufficient reaction rate can be stably obtained and the acid value of the product can be further reduced.
The metal alkoxide may be added in a powder state, or may be added as a lower alcohol solution such as methanol. The method of adding the metal alkoxide as a lower alcohol solution such as methanol is advantageous in that the catalyst can be uniformly dissolved in the reaction composition.

The addition temperature of the metal alkoxide is not particularly limited and may be appropriately selected depending on the purpose. However, the decomposition of the metal alkoxide with water in the mixed solution containing the polyol and the fatty acid lower alkyl ester as raw materials may be performed. In order to suppress, 60 to 90 degreeC is preferable, 60 to 85 degreeC is more preferable, and 70 to 80 degreeC is especially preferable. When the metal alkoxide is added within the preferred temperature range, the reaction proceeds rapidly with the addition of the metal alkoxide, so that moisture is also rapidly removed by removing the lower alcohol produced by the reaction out of the system by means such as reduced pressure. It is presumed that the reaction between the metal alkoxide and moisture is further suppressed.
In addition, even if it is outside the said preferable temperature range, the effect of this invention can be acquired even if it heats up quickly after charging the said metal alkoxide, and reaction is started.

<< Reaction method, conditions >>
In the low temperature reaction step (step 1), after the addition of the metal alkoxide, a transesterification reaction is performed at a temperature of 60 ° C. to 90 ° C., and the lower alcohol distilled out is removed from the system at the same time. The water content is distilled off to make the water content 100 mass ppm or less.

The temperature condition is not particularly limited as long as it is 60 ° C. to 90 ° C., and can be appropriately selected according to the purpose, but is preferably 60 to 85 ° C., more preferably 70 to 80 ° C.
If the temperature condition is less than 60 ° C., dehydration may not proceed because the transesterification reaction proceeds slowly, and if it exceeds 90 ° C., the catalyst activity may decrease.

In the low-temperature reaction step, the lower alcohol produced by the transesterification reaction is removed from the system, and at the same time, moisture can be entrained and the moisture can be efficiently removed in a short time.
There is no restriction | limiting in particular as a removal method of the said lower alcohol etc., It can select suitably according to the objective from well-known methods, for example. Examples thereof include a decompression method and a method using a gas such as nitrogen.
In the case of the decompression method, the pressure is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 50 kPa or less, and more preferably 30 kPa or less.

  There is no restriction | limiting in particular as reaction time of the said low temperature reaction process, Although it can select suitably according to the objective in the range from which water content will be 100 mass ppm or less, It is about 30 minutes-120 minutes.

There is no restriction | limiting in particular as long as it is 100 mass ppm or less as water content after reaction of the said low temperature reaction process, Although it can select suitably according to the objective, 70 mass ppm or less is preferable.
When the water content exceeds 100 ppm by mass, the reaction rate may decrease, and the full ester content in the finally obtained hindered polyol ester may decrease. On the other hand, when the water content is within the preferable range, it is advantageous in that a high reaction rate can be stably obtained.
The water content can be measured, for example, by a Karl Fischer moisture meter (trade name: AQV-7, manufactured by Hiranuma Sangyo Co., Ltd.).
In addition, the reaction rate (full ester content in the polyol and hindered polyol ester) when the water content becomes 100 mass ppm in the low-temperature reaction step is approximately 15 mass% to 30 mass%.

<Process 2>
The step 2 is a step of heating the reaction product of the step 1 to 160 ° C. to 250 ° C., maintaining the temperature within the temperature range, and further allowing the ester exchange reaction to proceed.
According to the production method of the present invention, by raising the temperature to 160 ° C. to 250 ° C., the transesterification reaction can be performed even when the amount of the catalyst is small compared to the conventional case, and the reaction rate is improved. The transesterification reaction can be completed in a short time.

  The temperature raising time is not particularly limited and may be appropriately selected depending on the intended purpose. The temperature raising time until reaching 160 ° C. is set to 60 minutes to 300 minutes. A hindered polyol ester having a desired reaction rate is particularly preferable because a full ester can be obtained without unnecessarily extending. After completion of the temperature increase, the temperature is maintained in the range of 160 ° C. to 250 ° C., and the transesterification reaction is further advanced.

  The temperature to be maintained is not particularly limited as long as it is 160 ° C to 250 ° C, and can be appropriately selected according to the purpose, but is preferably 180 ° C to 230 ° C, and particularly preferably 200 ° C to 220 ° C. When the temperature is less than 160 ° C., the reaction rate may decrease, and when it exceeds 250 ° C., coloring may be a problem. By setting it as the said preferable range, a full ester can be obtained with a high reaction rate with a smaller catalyst amount.

The reaction in Step 2 can be performed while removing the lower alcohol produced by the transesterification reaction under reduced pressure or a gas flow such as nitrogen under stirring and mixing.
The reaction method is not particularly limited and can be carried out by appropriately selecting a known method according to the purpose.

<Other processes>
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, the process of removing unreacted fatty-acid lower alkyl ester from the hindered polyol ester obtained at the said process 2 ( Hereinafter, it may be referred to as “fatty acid lower alkyl ester removal step”), and a step of removing the base component and acidic component derived from the metal alkoxide (hereinafter referred to as “base component or acidic component removal step”). ) And the like.

<< fatty acid lower alkyl ester removal step >>
In the fatty acid lower alkyl ester removal step, the method for removing the unreacted fatty acid lower alkyl ester is not particularly limited and may be appropriately selected from known methods according to the purpose. For example, vacuum distillation Law.

<< Base Component or Acid Component Removal Step >>
In the base component to acidic component removal step, the method for removing the base component and acidic component derived from the metal alkoxide is not particularly limited and may be appropriately selected depending on the intended purpose. The method etc. are mentioned.

-Adsorbent-
The adsorbent is not particularly limited as long as it can adsorb a base component and an acidic component, and can be appropriately selected according to the purpose. For example, an adsorbent capable of adsorbing a base component derived from a metal alkoxide (for example, , KYOWARD 700 (manufactured by Kyowa Chemical Industry Co., Ltd.)) and an absorbent capable of adsorbing metal alkoxide-derived acidic components (for example, KYOWARD 500 (manufactured by Kyowa Chemical Industry Co., Ltd.)), and the like. .
There is no restriction | limiting in particular as usage-amount of these adsorption agents, Although it can select suitably according to the objective, About 0.5 mass%-3 mass% are preferable with respect to a crude product.
Since the amount of the catalyst (metal alkoxide) added is small in the method for producing a hindered polyol ester of the present invention, a crude product having a lower acid value can be obtained. Therefore, the use of these adsorbents is advantageous in that a hindered polyol ester having a lower acid value can be obtained. On the other hand, the conventional production method with a large amount of catalyst cannot produce a hindered polyol ester having a sufficiently low acid value even if the adsorbent is used in the above-mentioned degree.

<Hindered polyol ester>
The production method of the present invention has a high reaction rate, does not require a water removal step, has a sufficiently high reaction rate, has few by-products such as fatty acids, and can obtain a full ester at a high reaction rate. Further, a hindered polyol ester having a lower acid value can be obtained.

There is no restriction | limiting in particular as said reaction rate, Although it can select suitably according to the objective, 95% or more is preferable, 98% or more is more preferable, and it is especially preferable that it is 100% (all are full esters). .
The reaction rate of the full ester is determined by, for example, analyzing the polyol (unreacted raw material), monoester, diester, and triester in the measurement sample by gas chromatography using the reaction product as the measurement sample. It can obtain | require by calculating the reaction rate of the polyol ester on the basis of a polyol from the area ratio of ester.

There is no restriction | limiting in particular as said acid value, Although it can select suitably according to the objective, 0.5 or less is preferable, 0.2 or less is more preferable, 0.1 or less is especially preferable. When the acid value exceeds 0.5, the stability may be deteriorated.
In the hindered polyol ester produced by the production method of the present invention, the acid value is derived from the fatty acid as a by-product, and it is preferable that the by-product is not contained. The lower limit of value is not critical.
The acid value can be measured according to, for example, JIS K2501.

  EXAMPLES The present invention will be specifically described below with reference to examples of the present invention, but the present invention is not limited to these examples.

<Evaluation method, measurement method>
In the following examples and comparative examples, the moisture content, the reaction rate, and the acid value were measured by the following measuring methods.

<< Method for measuring moisture content >>
The moisture content was measured with a Karl Fischer moisture meter (trade name: AQV-7, manufactured by Hiranuma Sangyo Co., Ltd.).

<< Method for measuring reaction rate >>
As the reaction rate, the polyol (raw material), monoester, diester, and triester are analyzed by gas chromatography under the following conditions, and the reaction rate of the polyol ester based on the polyol is calculated from the area ratio of the triester. did.
[Conditions for gas chromatography]
Apparatus: 5890 gas chromatograph (manufactured by Agilent Technologies)
Column: Product name J & W DB-1HT (manufactured by Agilent Technologies)
Oven temperature: 80 ° C. to 390 ° C., 10 ° C./min Vaporization chamber temperature: 390 ° C.
Detector temperature: 390 ° C (FID)
Carrier gas: helium

<< Method for Measuring Acid Value >>
The acid value was measured by potentiometric titration according to JIS K2501.

Example 1
<Step 1>
A glass reactor with a capacity of 5 L equipped with a condenser, thermometer and stirrer was charged with 680.4 g of trimethylolpropane (Mitsubishi Gas Chemical Co., Ltd.) and 2,888.4 g of methyl caprate (Lion Chemical Co., Ltd.). The temperature was raised to 80 ° C. with stirring. The water content (initial water content) of the reaction raw material mixture was 200 mass ppm.
After raising the temperature of the reaction mixture to 80 ° C., sodium methoxide 28 mass% methanol solution (genuine equivalent to 0.01 mass% with respect to the total mass 3,568.8 g of trimethylolpropane and methyl caprate) 1.275 g (manufactured by Chemical Co., Ltd.) (0.357 g, 0.0066 mol as a pure component) was added under atmospheric pressure conditions and 80 ° C. temperature conditions.
Immediately after the addition of the catalyst, the pressure is reduced and maintained for 60 minutes under a pressure condition of 4 kPa to 7 kPa and a temperature condition of 80 ° C. Then, the temperature is raised to 90 ° C. over 20 minutes, The transesterification was carried out while removing. When the temperature reached 90 ° C., the water content was 40 ppm by mass, and the reaction rate was 23.4%.

<Process 2>
Following the step 1, while removing methanol by-produced under reduced pressure, the temperature was raised from 90 ° C. to 160 ° C. over 280 minutes, and then the temperature was raised to 220 ° C. over 120 minutes. An exchange reaction was performed. To 2,600 g of the crude product obtained by the transesterification reaction, an adsorbent (26 g of trade name: Kyoward 700 and 26 g of trade name: Kyoward 500 (both manufactured by Kyowa Chemical Industry Co., Ltd.)) was added. After stirring for 60 minutes at 90 ° C., a PTFE filter (trade name: Omnipore Membrane, manufactured by Millipore) with a pore size of 0.45 μm and a filter aid (trade name: Hyflo Supercell, Tokyo Diatomite Industries, Ltd.) Manufactured; 0.8 kg / m ² ) with respect to the filtration area.
As a result, 2,510 g of trimethylolpropane caprylate having a reaction rate of 98.2% and an acid value of 0.04 mgKOH / g was obtained.

(Example 2)
<Step 1>
In a glass reactor similar to Example 1, 680.4 g of trimethylolpropane (Mitsubishi Gas Chemical Co., Ltd.) and 2,888.4 g of methyl caprate (Lion Chemical Co., Ltd.) were charged and stirred at 70 ° C. The temperature was raised to. Here, ion exchange water was added to adjust the water content (initial water content) of the reaction raw material mixture to 800 ppm by mass.
After adjusting the water content, 5.10 g of a sodium methoxide 28 mass% methanol solution (manufactured by Junsei Co., Ltd.) in an amount corresponding to 0.04 mass% with respect to the total mass of 3,568.8 g of trimethylolpropane and methyl caprate 1.43 g (0.026 mol) as a pure component was added under atmospheric pressure and at a temperature of 70 ° C.
Immediately after the addition of the catalyst, the pressure is reduced and maintained for 60 minutes under a pressure condition of 4 kPa to 7 kPa and a temperature condition of 70 ° C. Then, the temperature is raised to 90 ° C. over 30 minutes, The transesterification was carried out while removing. When the temperature reached 90 ° C., the water content was 60 ppm by mass, and the reaction rate was 20.6%.

<Process 2>
Continuing from step 1 above, while removing methanol by-produced under reduced pressure, the temperature was raised from 90 ° C. to 160 ° C. over 150 minutes, and then the temperature was raised to 220 ° C. over 240 minutes. An exchange reaction was performed. The crude product obtained by transesterification was adsorbed and filtered in the same manner as in Example 1.
As a result, 2,509 g of trimethylolpropane caprylate having a reaction rate of 99.4% and an acid value of 0.1 mgKOH / g was obtained.

(Comparative Example 1)
<Step 1>
In Step 1 of Example 2, the temperature rise and the temperature at the time of addition of the sodium methoxide 28% by mass methanol solution were changed to 100 ° C., and the pressure was reduced immediately after the addition of the catalyst, under pressure conditions of 4 kPa to 7 kPa, and at 100 ° C. The reaction in Step 1 of Comparative Example 1 was carried out in the same manner as in Step 1 of Example 2, except that the transesterification was carried out for 30 minutes under the temperature condition and removing methanol distilling in the condenser. went. After holding for 1 hour, the water content was 50 ppm by mass, and the reaction rate was 46.6%.

<Process 2>
Following the step 1, while removing methanol by-produced under reduced pressure, the temperature was raised from 100 ° C. to 160 ° C. over 120 minutes, and then the temperature was raised to 220 ° C. over 330 minutes. An exchange reaction was performed. The crude product obtained by transesterification was adsorbed and filtered in the same manner as in Example 1.
As a result, 2,502 g of trimethylolpropane caprylate having a reaction rate of 88.2% and an acid value of 0.1 mgKOH / g was obtained.

(Comparative Example 2)
<Step 1>
In Step 1 of Example 2, the pressure was reduced immediately after the addition of the catalyst, and the temperature was raised without taking the holding time under the pressure condition of 4 to 7 kPa and the temperature condition of 70 ° C., and from 70 ° C. in 30 minutes. The reaction of step 1 was performed in the same manner as step 1 of Example 2 except that the temperature was raised to 90 ° C.
When the temperature reached 90 ° C., the water content was 230 mass ppm and the reaction rate was 14.6%.

<Process 2>
While removing methanol produced as a by-product in step 1 under reduced pressure, the temperature was raised from 90 ° C. to 160 ° C. over 150 minutes, and then the ester exchange reaction was further carried out while raising the temperature to 220 ° C. over 300 minutes. went. The crude product obtained by transesterification was adsorbed and filtered in the same manner as in Example 1.
As a result, 2,510 g of trimethylolpropane caprylate having a reaction rate of 89.2% and an acid value of 0.1 mgKOH / g was obtained.

(Comparative Example 3)
<Step 1>
In Step 1 of Example 1, the pressure was reduced immediately after the addition of the catalyst, and the temperature was raised without taking the holding time under the pressure condition of 4 kPa to 7 kPa and the temperature condition of 80 ° C., and from 80 ° C. in 20 minutes. The reaction of Step 1 was performed in the same manner as Step 1 of Example 1 except that the temperature was raised to 90 ° C.
When the temperature reached 90 ° C., the moisture content was 140 ppm by mass, and the reaction rate was 20.2%.

<Process 2>
While removing methanol produced as a by-product in the step 1 under reduced pressure, the temperature was raised from 90 ° C. to 160 ° C. over 280 minutes, and then the temperature was raised to 220 ° C. over 180 minutes. went. The crude product obtained by transesterification was adsorbed and filtered in the same manner as in Example 1.
As a result, 2,490 g of trimethylolpropane caprylate having a reaction rate of 94.2% and an acid value of 0.1 mgKOH / g was obtained.

(Comparative Example 4)
<Step 1>
Step 1 of Comparative Example 4 was performed in the same manner as in Example 1.
When the temperature reached 90 ° C., the water content was 50 ppm by mass, and the reaction rate was 24.3%.

<Process 2>
Subsequent to step 1, the methanol produced as a by-product under reduced pressure is removed, the temperature is raised from 90 ° C. to 140 ° C. over 120 minutes, and then the transesterification reaction is further carried out while maintaining at 140 ° C. for 280 minutes. went. The crude product obtained by transesterification was adsorbed and filtered in the same manner as in Example 1.
As a result, 2,507 g of trimethylolpropane caprylate having a reaction rate of 90.1% and an acid value of 0.1 mgKOH / g was obtained.

(Comparative Example 5)
<Step 1>
A reaction raw material mixture having a moisture content (initial moisture) of 800 mass ppm was prepared in the same manner as in Step 1 of Example 2. Next, 12.7 g of a sodium methoxide 28% by mass methanol solution (manufactured by Junsei Co., Ltd.) in an amount corresponding to 0.1% by mass with respect to 3,568.8 g of the total mass of trimethylolpropane and methyl caprate 3.57 g, 0.07 mol) was added under atmospheric conditions and at a temperature of 70 ° C.
Immediately after the addition of the catalyst, the pressure is reduced and held for 120 minutes under a pressure condition of 4 kPa to 7 kPa and a temperature condition of 70 ° C. Then, the temperature is raised to 90 ° C. over 30 minutes, and the methanol distilled into the condenser is removed. The transesterification was carried out while removing. When the temperature reached 90 ° C., the water content was 60 ppm by mass, and the reaction rate was 77.6%.

<Process 2>
Subsequent to Step 1, while removing methanol by-produced under reduced pressure, the temperature was raised from 90 ° C. to 160 ° C. over 240 minutes, and then the ester exchange reaction was further carried out while maintaining at 160 ° C. for 90 minutes. went. The crude product obtained by transesterification was adsorbed and filtered in the same manner as in Example 1.
As a result, 2,507 g of trimethylolpropane caprylate having an acid value of 9 mg and an acid value of 0.3 mgKOH / g was obtained.

(Comparative Example 6)
<Step 1>
A reaction raw material mixture having a moisture content (initial moisture) of 800 mass ppm was prepared in the same manner as in Step 1 of Example 2. Next, 38.1 g of a sodium methoxide 28% by mass methanol solution (manufactured by Junsei Chemical Co., Ltd.) in an amount corresponding to 0.3% by mass with respect to the total mass of 3,568.8 g of trimethylolpropane and methyl caprate 10.7 g, 0.21 mol) was added under atmospheric pressure and at a temperature of 70 ° C.
Immediately after the addition of the catalyst, the pressure is reduced and held for 120 minutes under a pressure condition of 4 kPa to 7 kPa and a temperature condition of 70 ° C. Then, the temperature is raised to 90 ° C. over 30 minutes, and the methanol distilled into the condenser is removed. The transesterification was carried out while removing. When the temperature reached 90 ° C., the water content was 60 ppm by mass, and the reaction rate was 88.2%.

<Process 2>
Subsequent to the step 1, while removing methanol by-produced under reduced pressure, the temperature was raised from 90 ° C. to 120 ° C. over 60 minutes, and then the ester exchange reaction was further carried out while maintaining at 120 ° C. for 180 minutes. went. The crude product obtained by transesterification was adsorbed and filtered in the same manner as in Example 1.
As a result, 2,507 g of trimethylolpropane caprylate having a reaction rate of 99.0% and an acid value of 0.4 mgKOH / g was obtained.

  The reaction conditions and results of Examples 1 and 2 and Comparative Examples 1 to 6 are summarized in Table 1 and Table 2 below.

  From the results of Tables 1 and 2, it was found that in Examples 1 and 2, a reaction rate of 98% or more was obtained with a small amount of catalyst (0.01% by mass, 0.04% by mass). Moreover, in Examples 1-2, it turned out that the production | generation of a fatty acid salt is suppressed by reduction of a catalyst amount, and a base material with a small acid value is obtained by simple refinement | purification which does not include complicated processes, such as water washing. .

  The polyol ester produced by the method of the present invention has a high reaction rate, does not require a water removal step, has a sufficiently high reaction rate, and has a low acid value. It can be suitably used for engine oil such as lubricating oil, industrial gear oil, hydraulic hydraulic oil, textile lubricating oil, and the like.

Claims (2)

A method for producing a hindered polyol ester by transesterification of a polyol and a fatty acid lower alkyl ester using a metal alkoxide as a catalyst, comprising the following step 1 and step 2: .
Step 1: In a mixed solution containing the fatty acid lower alkyl ester having a water content of 150 ppm to 1,000 ppm by mass and the polyol, 0 is added to the total mass of the polyol and the fatty acid lower alkyl ester. 0.01% by mass to 0.05% by mass of the metal alkoxide was added, and the water in the system and the lower alcohol produced were distilled off at a temperature of 60 ° C. to 90 ° C. to remove the water in the mixture. The process which makes content 100 mass ppm or less.
Process 2: The process of heating to 160 to 250 degreeC following the said process 1, and maintaining in this temperature range. The ratio of the number of moles of fatty acid lower alkyl ester in step 1 / (number of moles of polyol x number of hydroxyl groups in one molecule of polyol) is 1.0 to 2.0. Production method.