JPH07145090A - Method for producing sorbitol stable to heat and/or alkali - Google Patents

Abstract

PURPOSE:To obtain sorbitol stable against heat and/or alkali by subjecting a sorbitol aqueous solution to an alkaline thermal treatment and subsequently purifying the treated product. CONSTITUTION:A sorbitol aqueous solution is adjusted to a pH of 9.5-14 with the hydroxide or carbonate of a metal such as Na, K or Ca, heated at 110-220 deg.C for 5min to 2hr, and subsequently subjected to an ion exchange resin treatment and, if necessary, further to an active carbon treatment for the desalting and decoloring treatment of the solution. Thus, the substantially decolored sorbitol useful as a raw material for synthesizing polyurethanes, alkyd resins, etc., and reduced in the content of non-reduced saccharides is obtained. Since this method is a simple process not causing the miss operation and not requiring a special device, the sorbitol is massively obtained at a low cost.

Description

Detailed Description of the Invention

[0001]

[Industrial applications]

The present invention relates to a method for producing sorbitol, which is stable to heat and / or alkali, and more specifically, to heat and / or alkali which can be used as a synthetic raw material for surfactants, polyurethanes, alkyd resins and the like with little coloring. On the other hand, the present invention relates to a method for producing sorbitol that is stable, that is, is less likely to be colored by heat and / or alkali, and has less unreduced sugar.

[0003]

[Prior Art and Problems to be Solved by the Invention]

As a typical sugar alcohol, sorbitol is widely used as a food, a raw material for medicines, and a synthetic raw material.

Among these applications, the sorbitol fatty acid ester obtained by reacting sorbitol with a fatty acid is a nonionic surfactant having a high hydrophilicity, has excellent surfactant activity and high safety, and further, sucrose. It is characterized by being relatively stable to heat and alkali compared to the fatty acid esters of.

However, since this esterification reaction is generally carried out at a high temperature in the presence of an alkali catalyst, the reaction product tends to be colored, and the decoloring operation is usually difficult.

For this reason, today, which is directed to high quality and high performance, it is required that sorbitol, which is a raw material for this material, be less colored even under reaction conditions where heat and / or alkali are present.

Also, sorbitol has a plurality of functional groups,
Furthermore, since it is more stable to heat and / or alkali than sugar, it is also used as a raw material for polyurethanes, alkyd resins, etc., but in order to produce a resin with less coloration, it can be used for sorbitol against heat and / or alkali. Improved stability is desired.

However, there is nothing to be found in the technology for producing sorbitol which is stable against heat and / or alkali.

In the laboratory, the reducing conditions were examined by using glucose and the like, which have been repeatedly purified, as a raw material to reduce impurities derived from the raw material and produce sorbitol stable to heat and / or alkali. Although attempts have been made to suppress the formation of impurities as much as possible, to thoroughly purify the sorbitol after reduction, and to remove as much as possible the substances that are considered to be the cause of coloring, the stability of the resulting sorbitol against heat and / or alkali The properties have not reached the level required at the time of manufacturing a surfactant or resin.

As an example in which it is expected that the stability to heat and / or alkali can be expected to improve, Japanese Patent Laid-Open No. 51-8640 is known.
In JP-A-6, reduction is carried out in an alkaline state in order to obtain sorbitol having high purity and low unreduced sugar.

However, this method is not industrially practical for the following reasons, and the heat and / or heat of the obtained sorbitol
Or the stability to alkali is not improved.

That is, this method requires a charging pump capable of withstanding an alkali, a pump for injecting a buffer, a device for monitoring and controlling pH, etc., which requires a high equipment cost and requires continuous addition during the reduction reaction. Such a buffer increases the subsequent purification load, and further, the coexistence of alkali and sugar inevitably results in the formation of oligosaccharides, resulting in a decrease in the purity of sorbitol.

As mentioned above, all of the sorbitols obtained by these techniques were only able to slightly reduce the coloration by heat and / or alkali, and the surfactants which require less coloration. Sorbitol that is stable against heat and / or alkali that can be used as a raw material for resins and resins has not been produced.

To explain the prior art in detail, it was said that the cause of low stability of sorbitol against heat and / or alkali was unreduced sugar present as an impurity in sorbitol.

Therefore, it was thought that the stability of sorbitol against heat and / or alkali could be improved by reducing the amount of unreduced sugar.

However, the unreduced sugar content is reduced to 0.05% or less based on the solid content by a general industrial method of reducing sugars, that is, a method of carrying out catalytic hydrogenation at high temperature and high pressure under a reducing catalyst such as Raney nickel. It was difficult.

A simple solution is to use a large amount of catalyst,
When the reduction reaction is carried out at a temperature higher than usual for a long time, the unreduced sugar sometimes becomes less than 0.05%, but in that case, the catalyst cost becomes too high to be ignored, and further sugar decomposition and isomerization occur. It was necessary to pay attention to the chemical reaction and suppress the formation of impurities.

Further, a method of reducing the obtained sorbitol to reduce the unreduced sugar was also considered, but the cost is high, and the expected reduction of the unreduced sugar is not obtained. Sorbitol heat and / or their prior art
Alternatively, there is a limit to the improvement of stability against alkali.

It should be noted that, in Japanese Patent Publication No. Sho 41-12212, an alkali is added to the solution immediately before the completion of the reduction reaction in the high-pressure hydrogenation reduction method to adjust the pH to 8 to 10 for further reduction or after completion of the reduction reaction. After adding alkali to the sorbit solution to adjust the pH to 8 to 10 and heating it to a temperature of 60 to 90 ° C., the remaining direct reducing sugars are decomposed, and then neutralized or not neutralized with an acid or decolorized or decolorized with decolorizing carbon. A method for producing a heat-resistant and alkali-resistant sorbite, which comprises economically producing the highest purity sorbite by filtering this and further purifying it with an ion exchange resin, is described.

However, according to the method for producing sorbit described in Japanese Patent Publication No. 41-12212, after adjusting the pH, 6
Under a temperature condition of 0 to 90 ° C., the reducing sugar is directly decomposed with a relatively long treatment time of about 5 hours, so that the amount of impurities produced is large and the stability against heat and / or alkali is insufficient. There wasn't.

The object of the present invention is to have sufficient stability to heat and / or alkali, to remove coloring-causing substances at low cost, and to be stable to heat and / or alkali which can be used as a raw material for synthesis. To provide industrial sorbitol.

[0023]

[Means for Solving the Problems]

The inventors of the present invention have deeply studied the method for improving the stability of sorbitol, and as a result, as described above, the stability of sorbitol against heat and / or alkali, and thus this sorbitol, even if the amount of unreduced sugar is minimized. It has been found that the coloring of a product such as a surfactant obtained by using as a raw material cannot be below a certain level.

It can be considered that the cause of coloring is not only unreduced sugar but also that derived from starch, which is a raw material of sugar, or trace components derived from saccharifying enzyme. The results have revealed that these substances cannot be completely removed by conventional purification means such as activated carbon or ion exchange.

The inventors of the present invention have made further diligent studies to solve the above-mentioned problems, and as a result, after adding an alkali to the sorbitol aqueous solution obtained by a usual method to adjust the pH, 110 ° C. or more and 220 ° C. By the simple means of heat treatment for 5 minutes to 2 hours, unreduced sugar, which is considered to be the largest cause of coloring, is reduced, and it is a coloring cause of unknown structure that is considered to be derived from raw sugar or enzyme. The present invention has been completed by modifying a trace amount of the substance and then removing the modified substance by a conventional purification means such as activated carbon or ion exchange.

The sorbitol used in the present invention is obtained by reducing crystalline glucose or liquid glucose with a reducing catalyst such as Raney nickel, and further enhances the stability of the present invention against heat and / or alkali. For this purpose, it is preferable to use refined and highly purified glucose, and the effect of the invention is more remarkable as the oligosaccharide contained in glucose is smaller.

The sorbitol used in the present invention is generally prepared by making sugar into an aqueous solution of 40 to 75% and charging it into a high pressure reactor while mixing and stirring with a reducing catalyst, and adjusting the hydrogen pressure in the reactor to 50 to 50%. 200 kg / cm ² , reaction liquid temperature 70 to 1
The reduction reaction is performed until the absorption of hydrogen is no longer observed while adjusting the temperature to 80 ° C. After the reaction is completed, the catalyst is separated, decolorized and desalted by ion exchange resin treatment, activated carbon treatment if necessary, and then concentrated to a predetermined concentration. Obtained. In the present invention, not only sorbitol obtained by the above method, but also commercially available sorbitol can be used as it is to achieve the object.

Next, the alkali heat treatment method for sorbitol according to the present invention will be described.

To an aqueous sorbitol solution having an appropriate concentration, preferably 20 to 60%, an alkali such as a hydroxide or carbonate of a metal such as sodium, potassium or calcium is added to adjust the pH.
Is adjusted to 9.5 or more and 14 or less, 110 ° C or more and 220 ° C
After heating at the following temperature for 5 minutes to 2 hours, ion-exchange resin treatment and activated carbon treatment if necessary are carried out by a conventional method.
The purpose can be achieved by performing desalting and decolorization purification.

The concentration of sorbitol is less than 20% or 60
Even if the content exceeds 100%, there is no problem in the effect of improving stability to heat and / or alkali, but if the concentration is too thin, the concentration cost in the subsequent step is high, and conversely if it is too concentrated. It is not industrial because the resin floats during processing in the subsequent ion exchange resin processing step.

The alkali to be added is preferably an aqueous solution of about 25%, but when the pH can be adjusted, a slurry state,
A solid alkali may be used.

The heating time is 5 minutes to 2 hours, which must be appropriately selected according to pH and temperature.

That is, the higher the pH and the higher the temperature, the shorter the heating time.

However, if the pH is too high, the ion exchange load for removing the added alkali increases, so p
H is preferably 13 or less, and when the heating temperature is too high, sorbitol may decompose to form a low boiling point substance, so heating at 140 ° C. or less is preferable.

Any heat treatment device may be used as long as it can maintain a temperature of 110 ° C. or higher, and it is not necessary to select the material.

For example, in the laboratory, the material of the reaction vessel may be glass or stainless steel, and the sorbitol solution whose pH is adjusted is put in this and heated on a burner, or if necessary, in a normal steam sterilization pot. Put in steam heat treatment at high pressure.

Industrially, continuous treatment is preferable in terms of thermal efficiency, equipment cost, etc., and mass production becomes easy.
Also in this case, it is not necessary to use a special material such as glass lining as the material of the liquid contact part, and stainless steel is sufficient.

Further, the subsequent purification treatment will be described. The heat-treated sorbitol liquid is cooled to a temperature at which there is no danger in work (generally 70 ° C. or lower) and treated with activated carbon, or with ion exchange resin treatment without activated carbon treatment. Then decolorize and desalt.

When the activated carbon is treated, it is preferable to use 0.1 to 5% of activated carbon based on the sorbitol solid content.

In the ion exchange resin treatment, the sorbitol liquid is passed through a cation resin tower, an anion resin tower and a mixed bed tower in this order.

Manufacturer of the ion exchange resin used,
The type and product number are not particularly limited, but good results are obtained by using a strongly acidic cation exchange resin for the cation resin and a weakly basic anion exchange resin for the anion resin, and in particular, the anion exchange resin has a high decolorizing property. Workability is better if you select one.

The sorbitol liquid after the ion-exchange purification is concentrated, if necessary, and used for various purposes.

The following examples are provided to further illustrate the present invention.

[0045]

[Example 1]

150 g of hydrous crystalline glucose, 125 g of water and 5 g of Raney nickel catalyst were charged into an electromagnetic stirring type autoclave having an internal volume of 550 ml, and hydrogen pressure was 130 kg.
/ Cm ² was maintained and reduced at 130 ° C. for 2 hours.

After separating this from the catalyst, it was treated with activated carbon and an ion exchange resin and concentrated to a concentration of 50% to obtain 250 g of a sorbitol liquid (this is designated as A).

When the unreduced sugar was measured by the Bertrand's method, the direct reducing sugar was 0.06% based on the solid content, and the total sugar was 0.17%.

200 g of the above-obtained (A) was placed in a 500 ml Erlenmeyer flask and a 25% aqueous sodium hydroxide solution was added to adjust the pH to 13.

This was put in a sterilization kettle and heated at 120 ° C. for 1 hour, then cooled to about 50 ° C., and 200 ml of cation exchange resin SK-1B and anion exchange resin WA-30.
(Both are manufactured by Mitsubishi Kasei Co., Ltd.) Furthermore, mixed bed resin (SK-1
B and WA-30 were mixed at a ratio of 1: 2) and concentrated to 50% to obtain 190 g of a sorbitol solution (this is referred to as B).

The direct reducing sugar was 0.02%, and the total sugar value was 0.16%.

In order to compare the thermal stability of (A) and (B), 5 g of 10% potassium hydroxide aqueous solution was added to and mixed with 60 g of each, and kept in boiling water for 30 minutes.

After cooling, the degree of coloring was measured.
APHA (color determination method set by the American Public Healthy Association) 120, while (B) has 3
It was 0.

Further by gas chromatography (A),
When the sorbitol content of (B) was measured, it was 99.5% for (A) and 99.6% for (B), showing almost no difference.

[0055]

Example 2

Commercially available sorbitol liquid (trade name: Solbit D-70, manufactured by Towa Kasei Co., Ltd .; unreduced sugar 0.07%)
Was made into a 50% aqueous solution (L), and the pH was adjusted to 10 with sodium hydroxide.

This was passed through a stainless steel pipe (injecting pump at the inlet and a pressure adjusting valve at the outlet so that a pressurized state could be maintained) immersed in an oil bath whose temperature was controlled at 140 ° C. .

The effective heating capacity of the stainless steel pipe was 21 ml (inner diameter 3 mmφ, length 3 m), and the injection amount was 3 ml / min.

200 g of the effluent was purified in the same manner as in (B) of Example 1 to obtain 185 g of 50% sorbitol solution (designated as M).

The unreduced sugar of (M) was 0.02%.

To compare the stability of (L) and (M) against heat and alkali, 10% was added to 60 g of each of (L) and (M).
5 g of an aqueous potassium hydroxide solution was added and mixed, and the mixture was kept at 98 ± 2 ° C. for 1 hour, and then the degree of coloring was measured.

The coloring degree of (L) was APHA120, while that of (M) was 20.

[0063]

【The invention's effect】

The sorbitol according to the present invention, which is stable against heat and / or alkali, has a small amount of unreduced sugar and a coloring-causing substance has been removed. By using such sorbitol as a raw material, it is possible to obtain a surfactant, a resin and the like with little coloring.

Furthermore, since the production method of the present invention is a simple process of heat treatment under constant conditions after pH adjustment,
There is no operation mistake and no skill is required.

Further, the manufacturing apparatus used for carrying out the manufacturing method of the present invention does not need to be special equipment, and the continuous operation apparatus can be installed at a low price. Therefore, the sorbitol according to the present invention has a low cost. It is possible to supply in large quantities.

Front Page Continuation (72) Inventor Yuji Nagata 3-12-15-401 Hikonari Misato City, Saitama Prefecture (72) Inventor Masaru Hidagi 9-1-204 Hiromi Nishihonmachi, Fuji City, Shizuoka Prefecture

Claims (1)

[Claims] 1. A sorbitol aqueous solution is treated with an alkali to remove p.
Adjusted to H9.5 or more and 14 or less, 110 ° C or more and 220 ° C
A method for producing sorbitol that is stable against heat and / or alkali, characterized by performing heat treatment at the following temperature for 5 minutes to 2 hours and then purifying.