JPH093201A - Decolorization of water-soluble polyamide and polyaspartic acid derivative - Google Patents

Abstract

PURPOSE: To obtain a water-soluble polyamide excellent in color tone and useful for dispersants, detergent builders, etc., by treating the water-soluble polyamide using a compound such s peroxodisulfate, etc., and carrying out a decoloring of the water-soluble polyamide effectively. CONSTITUTION: This decolorization of a water-soluble polyamide and a polyaspartic acid derivative comprises treating 1 pt.wt. water soluble polyamide such as polyaspartic acid and/or its salt, etc., with preferably 0.001-0.2 pt.wt of one or more compounds selected from the group consisting of peroxodisulfate, peroxoborate, dithionous acid, a bisulfite, a disulfite and an organic peroxide, at 40-80 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for decolorizing a water-soluble polyamide and a polyaspartic acid derivative.

[0002]

2. Description of the Related Art Conventionally, various methods as shown below have been known as a method for producing a water-soluble polyamide and a polyaspartic acid derivative which are less colored by polycondensation.

That is, in US Pat. No. 4,363,797, aspartic acid is polycondensed in a high-boiling organic solvent while azeotroping the organic solvent with water, and the obtained polysuccinimide is hydrolyzed with hydroxide. Disclosed is a method for producing polyaspartic acid and a salt thereof with less coloration by decomposition.

Further, Journal of Medicinal Chemistry, 1
973, Vol. 16, No. 8, 893-897 discloses a method for obtaining an almost colorless polysuccinimide by polycondensing aspartic acid in the presence of phosphoric acid. That is,
By using the polysuccinimide as a raw material, it is possible to obtain polyaspartic acid and a salt thereof and a polyaspartic acid derivative with little coloring.

Further, US Pat. No. 5,292,864 discloses a method of decolorizing an aqueous solution of polyaspartic acid and its salt using hydrogen peroxide, chlorine, ozone or the like as a decolorizing agent.

[0006]

However, in the method for obtaining polysuccinimide by polycondensation of aspartic acid in an organic solvent, it is necessary to separate the obtained polysuccinimide from the organic solvent. However, there is a problem in that it cannot be obtained at low cost. Further, according to the study by the inventors of the present application, it is hard to say that the effect of suppressing coloring by the above method is sufficient.

The method of obtaining polysuccinimide by polycondensing aspartic acid in the presence of phosphoric acid has a problem that the apparatus is corroded. Further, in the above method, it is necessary to separate the polysuccinimide after polycondensation from phosphoric acid. Therefore, there is a problem that the polysuccinimide cannot be obtained at a low cost.

When a compound such as hydrogen peroxide, chlorine, or ozone is used as a decolorizing agent, the operator is liable to cause chemical injury, and these compounds have a problem that they are highly toxic. . In addition, chlorine and ozone
Since it is a gas, it is difficult to handle.

Therefore, there is a demand for a decolorizing method which is simple and has an excellent decolorizing effect for water-soluble polyamides and polyaspartic acid derivatives.

An object of the present invention is to solve the above-mentioned problems, to provide a simple and easy decolorizing method,
That is, it is to provide a novel method for decolorizing a water-soluble polyamide and a polyaspartic acid derivative.

[0011]

[Means for Solving the Problems] The inventors of the present invention have proposed that, for water-soluble polyamides and polyaspartic acid derivatives,
As a result of earnest studies on a decolorizing method having a simple and excellent decolorizing effect, a group consisting of peroxodisulfate, peroxoborate, dithionite, bisulfite, disulfite, and organic peroxide By decolorizing with at least one compound selected from the above, it was found that the water-soluble polyamide and the polyaspartic acid derivative can be easily decolorized, and an excellent decolorizing effect is obtained, and the present invention was completed. Came to let.

That is, in the method for decolorizing a water-soluble polyamide according to the first aspect of the present invention, in order to solve the above problems, a water-soluble polyamide is used as a peroxodisulfate, a peroxoborate, a dithionite or a sulfite. At least one selected from the group consisting of hydrogen salts, disulfites, and organic peroxides
It is characterized by bleaching with certain compounds.

In order to solve the above-mentioned problems, the method for decolorizing a water-soluble polyamide according to a second aspect is the method for decolorizing a water-soluble polyamide according to the first aspect, wherein the water-soluble polyamide is polyaspartic acid and And / or a salt thereof.

In order to solve the above-mentioned problems, the method of decolorizing a polyaspartic acid derivative according to a third aspect of the present invention comprises converting the polyaspartic acid derivative into a peroxodisulfate salt, a peroxoborate salt, a dithionite salt, or a sulfite. It is characterized in that it is decolorized by using at least one compound selected from the group consisting of hydrogen salt, bisulfite, and organic peroxide.

Hereinafter, the present invention will be described in detail. The water-soluble polyamide in the present invention is not particularly limited, and specifically, for example, water-soluble polyamides such as polyaspartic acid and its salts, polyasparagine, poly (2-hydroxyethyl) aspartic acid amide, etc. Polyaspartic acid derivatives; polyglutamic acid and salts thereof, water-soluble polyglutamic acid derivatives such as polyglutamine, and the like. Among these water-soluble polyamides, polyaspartic acid and its salts are preferable because they are particularly suitable for the decolorizing method of the present invention.

Specific examples of the polyaspartic acid salt include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as magnesium salt and calcium salt; ammonium salt; alkylamine salt; alkanolamine. Examples thereof include salts, but are not particularly limited.

The method for producing the polyaspartic acid and its salt is not particularly limited, and various conventionally known methods can be used. Of these, polysuccinimide obtained by thermal polymerization of aspartic acid, or thermal polymerization of ammonium salt and / or amide of at least one acid selected from the group consisting of maleic acid, fumaric acid, and malic acid. The method of subjecting the obtained polysuccinimide to alkaline hydrolysis using a basic compound such as sodium hydroxide is preferable because polyaspartic acid and a salt thereof suitable for the decolorizing method of the present invention can be obtained. The optical activity of aspartic acid, which is a raw material of the polysuccinimide, is not particularly limited and may be any of L-form, D-form, and DL-form. In addition, the above-mentioned aspartic acid, maleic acid,
It is also possible to polymerize an ammonium salt and / or amide of an acid such as fumaric acid or malic acid in an organic solvent to obtain polysuccinimide, and then subject the polysuccinimide to alkaline hydrolysis.

Corresponding by copolymerizing the above-mentioned aspartic acid or ammonium salt and / or amide of an acid such as maleic acid, fumaric acid, malic acid and the like with another compound copolymerizable with the compound. You may obtain polysuccinimides. As the copolymerizable compound, specifically, for example, glutamic acid, alanine, arginine, cystine, glycine, histidine, isoleucine,
Examples thereof include amino acids such as leucine, lysine, methionine, phenylalanine, proline, serine, threonine, valine and tryptophan, and amic acid, but are not particularly limited. That is, the polysuccinimide, which is a raw material of the polyaspartic acid and its salt in the present invention, may be a polymer having a succinimide structure. That is, in the present invention, polyaspartic acid and its salt refer to a polymer having an aspartic acid structure.

The production conditions of the polysuccinimide, that is, the reaction conditions such as the reaction temperature and the reaction time are not particularly limited, and may be appropriately set so that the above reactions are completed.

That is, the method for producing the water-soluble polyamide is not particularly limited, and the water-soluble polyamide can be produced by various conventionally known methods. Further, the production conditions of the water-soluble polyamide, that is, the reaction conditions such as reaction temperature and reaction time,
It is not particularly limited, and may be appropriately set so that the reaction is completed depending on the raw material used.

The polyaspartic acid derivative in the present invention is a polyaspartic acid derivative other than the above-mentioned water-soluble polyaspartic acid derivative, and is a polymer having an aspartic acid structure.

The method for producing the polyaspartic acid derivative is as follows:
It is not particularly limited, and it can be manufactured using various conventionally known methods. That is, it can be easily obtained by reacting the polysuccinimide with another compound necessary for obtaining a desired polyaspartic acid derivative. Further, the production conditions of the polyaspartic acid derivative, that is, the reaction conditions such as reaction temperature and reaction time are
It is not particularly limited, and may be appropriately set so that the above reaction is completed.

According to the invention, the water-soluble polyamide and / or polyaspartic acid derivative is treated with peroxodisulfate, peroxoborate, dithionite, bisulfite, disulfite, and The water-soluble polyamide and / or polyaspartic acid derivative can be easily decolorized by decolorizing by using at least one compound selected from the group consisting of organic peroxides as a decolorizing agent.

The peroxodisulfate is not particularly limited, but sodium peroxodisulfate, potassium peroxodisulfate, and ammonium peroxodisulfate are preferable because they are easily available.

The peroxoborate salt is not particularly limited, but sodium peroxoborate is
It is preferable because it is easily available.

The dithionite salt is not particularly limited, but sodium dithionite is preferable because it is easily available.

The bisulfite salt is not particularly limited, but sodium bisulfite and potassium bisulfite are preferable because they are easily available.

The disulfite is not particularly limited, but sodium disulfite is preferable because it is easily available.

The organic peroxide is not particularly limited, but water-soluble organic peroxides such as water-soluble hydroperoxides, water-soluble diacyl peroxides, and water-soluble peroxyesters can be used in the present invention. It is preferable because the effect of can be further improved. Among water-soluble hydroperoxides, t-butyl hydroperoxide is
It is preferable because it is easily available. Among the water-soluble diacyl peroxides, succinic acid peroxide is preferable because it is easily available. Among water-soluble peroxyesters, t-butyl peroxymaleate is
It is preferable because it is easily available. The organic peroxide other than the water-soluble organic peroxide is not particularly limited, but formic acid, peracetic acid, and perbenzoic acid are preferable because they are easily available.

The above various compounds may be used alone or in a suitable mixture of two or more kinds. That is, any combination may be used.

Compounds such as the above-mentioned peroxodisulfates, peroxoborates, dithionite salts, bisulfite salts, disulfite salts, and organic peroxides used as decolorizing agents in the present invention (hereinafter, for convenience of explanation) , Collectively referred to as decolorizing agents) are solids or liquids. Further, since the decolorizing agent is not highly toxic like compounds such as hydrogen peroxide, chlorine and ozone used in conventional decolorizing methods,
It is safe and easy to handle. Furthermore, the decolorizing agent can exhibit an excellent decolorizing effect. Among these decolorizing agents, peroxodisulfate, dithionite,
And bisulfite are particularly preferable because they can further improve the effects of the present invention. That is, by using peroxodisulfate, dithionite, and bisulfite, the water-soluble polyamide and / or polyaspartic acid derivative can be decolorized more easily and efficiently and uniformly.

The aqueous medium is not particularly limited, and water or a mixed solvent of water and a water-soluble organic solvent can be used. Among these aqueous media, water alone is the most preferable because it is easy to treat. The organic solvent is not particularly limited as long as it is a water-soluble organic solvent.

The method of adding the decolorizing agent when decolorizing the water-soluble polyamide or polyaspartic acid derivative is not particularly limited, and the decolorizing agent is collectively added to the solution of the water-soluble polyamide or polyaspartic acid derivative. It may be added, or may be added sequentially and dividedly. Of these decolorizing agent addition methods, the method of sequentially adding the decolorizing agent to the solution of the water-soluble polyamide or the polyaspartic acid derivative little by little is more effective than the method of adding the decolorizing agent all at once. Because the reaction can be suppressed,
It is suitable.

The form of the decolorizing agent when the decolorizing agent is added to the water-soluble polyamide or polyaspartic acid derivative is not particularly limited, and it may be solid or liquid. The liquid is preferable because it is easier to operate. When the decolorizing agent is solid, it may be added as an aqueous solution.

The pH of the water-soluble polyamide or polyaspartic acid derivative to be treated (pH in an aqueous medium such as water) is not particularly limited, and can be adjusted appropriately depending on the type of decolorizing agent. Good. Or pH
The decolorizing agent to be added may be selected depending on the type.

The amount of the decolorizing agent added to the water-soluble polyamide or polyaspartic acid derivative may be appropriately set depending on the desired degree of decolorization, and is not particularly limited, but 1 part by weight of the water-soluble polyamide or poly Decolorizing agent 0.0 per 1 part by weight of aspartic acid derivative
The range of 01 to 0.2 parts by weight is preferable. If the addition amount of the decolorizing agent is less than 0.001 part by weight, the water-soluble polyamide or the polyaspartic acid derivative cannot be efficiently decolorized, and there is a possibility that a sufficient decolorizing effect may not be obtained, which is preferable. Absent. On the other hand, even if the addition amount of the decolorizing agent is more than 0.2 parts by weight, no further effect is observed and the added decolorizing agent may be wasted.
Not preferred.

The temperature at which the water-soluble polyamide or polyaspartic acid derivative is decolorized with the decolorizing agent, that is,
The treatment temperature in the decolorizing treatment may be appropriately set depending on the decolorizing agent to be added, and is not particularly limited,
At normal pressure, it is preferably within the range of 20 ° C to boiling point, more preferably within the range of 40 ° C to 80 ° C. If the treatment temperature is lower than 20 ° C., the time required for decolorization becomes long and the productivity may decrease, which is not preferable. On the other hand, for example, in the case of performing decolorization under pressure, if the treatment temperature is higher than the boiling point under normal pressure, side reactions such as decomposition may occur, which is not preferable. The processing pressure is not particularly limited.

The treatment time in the decolorization treatment of the above water-soluble polyamide or polyaspartic acid derivative may be appropriately set according to the type of the decolorizing agent, the treatment temperature, the desired degree of decolorization, etc., and is not particularly limited. is not.

As described above, the water-soluble polyamide and the polyaspartic acid derivative are selected from the group consisting of peroxodisulfate, peroxoborate, dithionite, bisulfite, disulfite, and organic peroxide. By decolorizing using at least one selected compound as a decolorizing agent, the water-soluble polyamide and the polyaspartic acid derivative can be easily decolorized, and an excellent decolorizing effect can be obtained.

The water-soluble polyamides and polyaspartic acid derivatives, particularly polyaspartic acid and its salts, are useful as dispersants, scale inhibitors, builders for detergents and the like.

[0041]

By decolorizing the water-soluble polyamide and the polyaspartic acid derivative using the method of the present invention, the water-soluble polyamide and the polyaspartic acid derivative can be easily decolorized and an excellent decolorizing effect can be obtained. You can

[0042]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 A reaction vessel (flask) equipped with a thermometer, a gas blowing tube, a stirrer, etc.,
100 g of L-aspartic acid was charged. This reaction vessel
It was immersed in an oil bath at 250 ° C., and L-aspartic acid was stirred in a nitrogen atmosphere for 3 hours to cause thermal polymerization. After the completion of the reaction, the reaction vessel was cooled to obtain 72 g of polysuccinimide.

A 48% by weight aqueous solution of sodium hydroxide was added to a slurry obtained by dispersing the obtained polysuccinimide in water, and alkali hydrolysis was carried out until the polysuccinimide was completely dissolved. From pH 9
Adjustment to 10 gave an aqueous solution of sodium polyaspartate. Then, the concentration of the obtained aqueous solution was adjusted to 40% by weight.

Then, 13.7 g of the above 40 wt% sodium polyaspartate aqueous solution was placed in another reaction vessel equipped with a thermometer, a gas blowing tube, a dropping device, a stirrer and the like.
Was charged. Next, the sodium polyaspartate aqueous solution was heated to 55 ° C. under a nitrogen atmosphere. On the other hand, 4.8 g of a 10% by weight sodium peroxodisulfate aqueous solution, which is a peroxodisulfate, was charged into the dropping apparatus. 4.8 g of the 10% by weight aqueous sodium peroxodisulfate solution corresponds to 0.002 mol of sodium peroxodisulfate. afterwards,
The sodium peroxodisulfate aqueous solution was added dropwise to the sodium polyaspartate aqueous solution over 30 minutes. After dropping, sodium polyaspartate was decolorized by reacting for 1 hour while keeping the reaction solution at 55 ° C. After adjusting the concentration of this sodium polyaspartate aqueous solution to 30% by weight, Gardner
The color tone of the sodium polyaspartate aqueous solution was measured using a color difference meter. Table 1 shows the results.

Example 2 In Example 1, 2.1 g of a 10 wt% sodium bisulfite aqueous solution, which is a hydrogen sulfite, was used in place of the sodium peroxodisulfate aqueous solution, and the temperature for decolorization was 55 ° C. to 65 ° C. Except changed to
The same reaction and operation as in Example 1 were carried out to decolorize sodium polyaspartate. 2.1 g of the above 10 wt% sodium hydrogen sulfite aqueous solution is sodium hydrogen sulfite.
This corresponds to 0.002 mol. The same procedure as in Example 1 was performed on the aqueous sodium polyaspartate solution, and the color tone was measured. Table 1 shows the results.

Example 3 The same reactor as in Example 1 was charged with 13.7 g of the 40 wt% sodium polyaspartate aqueous solution obtained in Example 1. Next, the sodium polyaspartate aqueous solution was heated to 80 ° C. under a nitrogen atmosphere. On the other hand, 0.052 g of a 69% by weight aqueous t-butyl hydroperoxide solution, which is an organic peroxide, was placed in the dropping apparatus. Incidentally, 0.052 g of the above 69 wt% t-butyl hydroperoxide aqueous solution was added to t-butyl hydroperoxide 0.00
Equivalent to 04 moles. Then, the above-mentioned t-butyl hydroperoxide aqueous solution was added dropwise to the sodium polyaspartate aqueous solution over 10 minutes. After the dropping, the reaction solution was reacted at a reflux temperature for 3 hours to decolorize sodium polyaspartate. This sodium polyaspartate aqueous solution was subjected to the same operations as in Example 1 to measure the color tone. Table 1 shows the results.

[Comparative Example 1] An aqueous sodium polyaspartate solution was obtained in the same manner as in Example 1, except that the decolorizing treatment using the aqueous sodium peroxodisulfate solution was not performed. That is, the aqueous solution of sodium polyaspartate obtained by thermal polymerization of L-aspartic acid was adjusted so that the concentration of sodium polyaspartate was 30% by weight. This sodium polyaspartate aqueous solution was subjected to the same operations as in Example 1 to measure the color tone. Table 1 shows the results.

Example 4 A reaction vessel similar to that of Example 1 was charged with 100 g of DL-aspartic acid. This reaction vessel was immersed in an oil bath at 230 ° C., DL-aspartic acid was stirred in a nitrogen atmosphere for 7 hours to carry out thermal polymerization.
After the completion of the reaction, the reaction vessel was cooled to obtain 71 g of polysuccinimide.

Using the obtained polysuccinimide, the same hydrolysis and operation as in Example 1 were carried out to obtain a 40 wt% sodium polyaspartate aqueous solution.

Next, in a reaction vessel similar to that of Example 1, the above
13.7 g of 40 wt% sodium polyaspartate aqueous solution was charged. Then, the sodium polyaspartate aqueous solution was heated to 50 ° C. under a nitrogen atmosphere. On the other hand, a 10 wt% sodium dithionite aqueous solution that is a dithionite salt
5.2 g was charged to the dropping device. Incidentally, 5.2 g of the 10% by weight sodium dithionite aqueous solution corresponds to 0.003 mol of sodium dithionite. Then, the sodium dithionite aqueous solution was added dropwise to the sodium polyaspartate aqueous solution over 30 minutes. After the dropping, by reacting the above reaction solution at 50 ° C. for 1 hour,
The sodium polyaspartate was decolorized. This sodium polyaspartate aqueous solution was subjected to the same operations as in Example 1 to measure the color tone. Table 1 shows the results.

[Comparative Example 2] An aqueous sodium polyaspartate solution was obtained in the same manner as in Example 4, except that the decolorizing treatment using the aqueous sodium dithionite solution was not performed. That is, an aqueous solution of sodium polyaspartate obtained by thermal polymerization of DL-aspartic acid is used as a solution containing sodium polyaspartate at a concentration of
It was adjusted to be 30% by weight. This sodium polyaspartate aqueous solution was subjected to the same operation as in Example 4, that is, Example 1 to measure the color tone. Table 1 shows the results.

Example 5 The same reactor as in Example 1 was charged with 100 g of ammonium maleate. This reaction vessel was immersed in an oil bath at 250 ° C., and ammonium maleate was stirred in a nitrogen atmosphere for 1.5 hours to carry out thermal polymerization. After completion of the reaction, the reaction vessel was cooled to obtain 75 g of polysuccinimide.

Using the obtained polysuccinimide, the same hydrolysis and operation as in Example 1 were carried out to obtain a 40% by weight aqueous sodium polyaspartate solution.

Next, in a reaction vessel similar to that of Example 1, the above
13.7 g of 40 wt% sodium polyaspartate aqueous solution was charged. Then, the sodium polyaspartate aqueous solution was heated to 45 ° C. under a nitrogen atmosphere. On the other hand, 4.0 g of a 10 wt% sodium peroxoborate aqueous solution, which is a peroxoborate salt, was charged into the dropping device. In addition, 4.0 g of the 10% by weight sodium peroxoborate aqueous solution corresponds to 0.004 mol of sodium peroxoborate. afterwards,
The sodium peroxoborate aqueous solution was added dropwise to the sodium polyaspartate aqueous solution over 30 minutes. After the dropping, sodium polyaspartate was decolorized by reacting for 2 hours while keeping the reaction solution at 45 ° C. This sodium polyaspartate aqueous solution was subjected to the same operations as in Example 1 to measure the color tone. Table 1 shows the results.

Example 6 The same reactor as in Example 5, ie, Example 1, was charged with 13.7 g of the 40 wt% sodium polyaspartate aqueous solution obtained in Example 5. Next, the sodium polyaspartate aqueous solution was heated to 80 ° C. under a nitrogen atmosphere. On the other hand, it is an organic peroxide, 10
0.75 g of a wt% aqueous t-butyl peroxymaleate solution was placed in the dropping apparatus. Incidentally, 0.75 g of the 10% by weight t-butyl peroxymaleate aqueous solution corresponds to 0.0004 mol of t-butyl peroxymaleate. Then, the above-mentioned t-butyl peroxymaleate aqueous solution was added dropwise to the sodium polyaspartate aqueous solution over 10 minutes. After the dropping, sodium polyaspartate was decolorized by reacting at reflux temperature for 2 hours. Regarding this aqueous solution of sodium polyaspartate, Example 5, that is,
The same operation as in Example 1 was performed to measure the color tone. Table 1 shows the results.

Example 7 The same reactor as in Example 5, ie, Example 1, was charged with 13.7 g of the 40 wt% sodium polyaspartate aqueous solution obtained in Example 5. Then, the sodium polyaspartate aqueous solution was heated to 50 ° C. under a nitrogen atmosphere. On the other hand, it is an organic peroxide 32
0.095 g of a weight% peracetic acid aqueous solution was charged into the dropping apparatus.
In addition, 0.095 g of the above 32% by weight aqueous solution of peracetic acid is 0.00
Equivalent to 04 moles. Then, the aqueous solution of peracetic acid was added dropwise to the aqueous solution of sodium polyaspartate over 10 minutes. After the dropping, sodium polyaspartate was decolorized by reacting for 1 hour while maintaining the reaction solution at 50 ° C. This sodium polyaspartate aqueous solution was subjected to the same operation as in Example 5, that is, Example 1 to measure the color tone. Table 1 shows the results.

[Comparative Example 3] An aqueous sodium polyaspartate solution was obtained in the same manner as in Example 5, except that the decolorization treatment using the aqueous sodium peroxoborate solution was not performed. That is, an aqueous sodium polyaspartate solution obtained by thermal polymerization of ammonium maleate was adjusted so that the concentration of sodium polyaspartate was 30% by weight. Regarding this aqueous solution of sodium polyaspartate, Example 5, that is,
The same operation as in Example 1 was performed to measure the color tone. Table 1 shows the results.

Example 8 The same reactor as in Example 1 was charged with 100 g of ammonium fumarate. This reaction vessel was immersed in an oil bath at 250 ° C., and ammonium fumarate was stirred in a nitrogen atmosphere for 1.5 hours to cause thermal polymerization. After the completion of the reaction, the reaction vessel was cooled to obtain 77 g of polysuccinimide.

Using the obtained polysuccinimide, the same hydrolysis and operation as in Example 1 were carried out to obtain a 40% by weight aqueous sodium polyaspartate solution.

Next, in a reaction vessel similar to that of Example 1, the above
13.7 g of 40 wt% sodium polyaspartate aqueous solution was charged. Next, the sodium polyaspartate aqueous solution was heated to 60 ° C. under a nitrogen atmosphere. On the other hand, an organic peroxide of 80% by weight succinic acid peroxide aqueous solution 0.12
g was charged to the dropping device. In addition, 0.12 g of the 80% by weight aqueous succinic acid peroxide solution is 0.02% of succinic acid peroxide.
Equivalent to 04 moles. Then, to the sodium polyaspartate aqueous solution, the succinic acid peroxide aqueous solution,
It was added dropwise over 10 minutes. After the dropping, sodium polyaspartate was decolorized by reacting for 2 hours while keeping the reaction solution at 60 ° C. This sodium polyaspartate aqueous solution was subjected to the same operations as in Example 1 to measure the color tone. Table 1 shows the results.

[Comparative Example 4] An aqueous sodium polyaspartate solution was obtained in the same manner as in Example 8, except that the decolorization treatment using the aqueous succinic acid peroxide solution was not performed. That is, the sodium polyaspartate aqueous solution obtained by thermal polymerization of ammonium fumarate,
It was adjusted to be 30% by weight. This sodium polyaspartate aqueous solution was subjected to the same operation as in Example 8, that is, Example 1 to measure the color tone. Table 1 shows the results.

[0063]

[Table 1]

As is clear from the results shown in Table 1, the sodium polyaspartate aqueous solutions obtained in Examples 1, 2 and 3 were more colored than the sodium polyaspartate aqueous solution obtained in Comparative Example 1. It turned out that there are few.
Further, it was found that the sodium polyaspartate aqueous solution obtained in Example 4 was less colored than the sodium polyaspartate aqueous solution obtained in Comparative Example 2.
Further, it was found that the sodium polyaspartate aqueous solutions obtained in Examples 5, 6, and 7 were less colored than the sodium polyaspartate aqueous solution obtained in Comparative Example 3. Further, it was found that the sodium polyaspartate aqueous solution obtained in Example 8 was less colored than the sodium polyaspartate aqueous solution obtained in Comparative Example 4.

That is, according to this example, an aqueous sodium polyaspartate solution was added to the group consisting of peroxodisulfate, peroxoborate, dithionite, bisulfite, disulfite, and organic peroxide. It was found that the sodium polyaspartate can be decolorized by using at least one compound selected from the above as a decolorizing agent. Further, all of the above decolorizing agents are solid or liquid, and are safe and easy to handle because they are not highly toxic like compounds such as hydrogen peroxide, chlorine and ozone used in conventional decolorizing methods. Is.

That is, by using the decolorizing method of the present invention, the water-soluble polyamide and the polyaspartic acid derivative can be easily decolorized, and an excellent decolorizing effect can be obtained.

[0067]

As described above, the method for decolorizing a water-soluble polyamide according to the present invention comprises converting the water-soluble polyamide into a peroxodisulfate salt, a peroxoborate salt, a dithionite salt, a bisulfite salt, a disulfite salt, and It is a method of decolorizing using at least one compound selected from the group consisting of organic peroxides.

As described above, the method of decolorizing the water-soluble polyamide of the present invention is a method in which the water-soluble polyamide is polyaspartic acid and / or a salt thereof.

Further, in the method for decolorizing a polyaspartic acid derivative of the present invention, as described above, the polyaspartic acid derivative is treated with peroxodisulfate, peroxoborate, dithionite, bisulfite or disulfite. And at least one compound selected from the group consisting of organic peroxides.

By decolorizing the water-soluble polyamide and the polyaspartic acid derivative using the method of the present invention, the water-soluble polyamide and the polyaspartic acid derivative can be easily decolorized and an excellent decolorizing effect can be obtained. There is an effect that can be.

Claims (3)

[Claims] 1. A water-soluble polyamide containing at least one compound selected from the group consisting of peroxodisulfate, peroxoborate, dithionite, bisulfite, disulfite, and organic peroxide. A method for decolorizing a water-soluble polyamide, which comprises decolorizing by using the method. 2. The method for decolorizing a water-soluble polyamide according to claim 1, wherein the water-soluble polyamide is polyaspartic acid and / or a salt thereof. 3. A polyaspartic acid derivative containing at least one compound selected from the group consisting of peroxodisulfate, peroxoborate, dithionite, bisulfite, disulfite, and organic peroxide. A method for decolorizing a polyaspartic acid derivative, which comprises decolorizing using a.