JP2007119533A - Chitosan derivative and polymer coagulant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chitosan derivative having a more improved coagulating performance than those of conventional chitosan derivatives, and to provide a polymer coagulant using the same. <P>SOLUTION: This polymer coagulant contains a chitosan derivative having repeating units to whose 6-hydroxy groups carbamoyl groups substituted with alkylamino groups are introduced, as an active ingredient. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel chitosan derivative and a polymer flocculant containing the chitosan derivative as an active ingredient.

で表される繰り返し単位を含むキトサンが、天然成分起源の高分子凝集剤として、広く、一般に用いられている。キトサンは、酸性水溶液に溶解させることで、凝集力を生じて、高分子凝集剤として機能させることができる。キトサンの凝集性能は、主として、キトサン分子の、高分子鎖としての凝集力と、側鎖であるアミノ基が、酸と反応して４級アミン化することで生じるカチオンの凝集力に基づいている。しかし、キトサンの、高分子凝集剤としての凝集性能は、未だ満足の行くものではなく、十分な凝集力を得るためには、多量のキトサンを使用する必要がある。そのため、キトサンの分子構造を改変して、凝集性能を向上することが検討されている。 Formula (3), obtained by deacetylating chitin:

Chitosan containing a repeating unit represented by the following formula is widely used as a polymer flocculant derived from natural ingredients. Chitosan can be made to function as a polymer flocculant by generating cohesive force by dissolving in an acidic aqueous solution. Chitosan's aggregation performance is mainly based on the aggregation force of chitosan molecules as a polymer chain and the cation's aggregation force generated by the reaction of an amino group as a side chain with an acid to form a quaternary amination. . However, the flocculation performance of chitosan as a polymer flocculant is not yet satisfactory, and it is necessary to use a large amount of chitosan in order to obtain a sufficient cohesive force. Therefore, it has been studied to improve the aggregation performance by modifying the molecular structure of chitosan.

〔式中、Ｒ⁴、Ｒ⁵は低級アルキル基を示し、Ｒ⁶は低級アルキレン基を示す。〕
で表される置換アミノ基に置換すると共に、前記アミノ基の残りの少なくとも一部を、式(5)：

〔式中、Ｒ⁷はアルキレン基、ｍは０または１を示す。〕
で表される架橋基に置換することで、複数のキトサン分子間、または同一のキトサン分子内に架橋構造を導入したキトサン誘導体が記載されている。
特開平１１−６０６０７号公報 For example, Patent Document 1 discloses that at least a part of the amino group of chitosan is represented by the formula (4):

[Wherein, R ⁴ and R ⁵ represent a lower alkyl group, and R ⁶ represents a lower alkylene group. ]
And at least a part of the remaining amino group is represented by formula (5):

[Wherein R ⁷ represents an alkylene group, and m represents 0 or 1. ]
A chitosan derivative in which a crosslinked structure is introduced between a plurality of chitosan molecules or in the same chitosan molecule is described.
Japanese Patent Laid-Open No. 11-60607

  However, in the chitosan derivative described in Patent Document 1, diethylaminoethyl chloride is reacted with at least a part of the amino group of chitosan to introduce a substituted amino group of the above formula (4), All amino groups are involved in aggregation because they have a structure in which chitosan molecules or two amino groups in the same chitosan molecule are partially crosslinked with a crosslinking group of formula (5). The aggregation performance may not be greatly improved.

  An object of the present invention is to provide a chitosan derivative having a further improved aggregation performance than before and a polymer flocculant using the chitosan derivative.

〔式中、Ｘは、式(2)：

で表される基を示し、式(2)中のＲ¹は低級アルキレン基、Ｒ²およびＲ³は、同一または異なって、水素原子または低級アルキル基を示す。〕
で表される繰り返し単位を含むことを特徴とするキトサン誘導体である。 The invention according to claim 1 has the formula (1):

[Wherein X is the formula (2):

In the formula (2), R ¹ is a lower alkylene group, R ² and R ³ are the same or different and each represents a hydrogen atom or a lower alkyl group. ]
It is a chitosan derivative characterized by including the repeating unit represented by these.

  The invention according to claim 2 is synthesized from chitosan, and the proportion of the repeating unit represented by formula (1) in all repeating units is 20 mol% or more. Is a derivative.

  A third aspect of the present invention is a polymer flocculant comprising the chitosan derivative according to the first or second aspect as an active ingredient.

  The chitosan derivative of the invention according to claim 1 includes a total of three amino groups in the repeating unit represented by the formula (1), one derived from chitosan and two in the group represented by the formula (2). Therefore, in an acidic aqueous solution, the cohesive force of a cation generated by reacting an amino group with an acid to form a quaternary amination can be enhanced. Therefore, coupled with the cohesive force of the chitosan derivative molecule as a polymer chain, the cohesive performance can be further improved than before.

  The chitosan derivative can be synthesized from chitosan, and considering that the effect of improving the aggregation performance by the three amino groups in the synthesized chitosan derivative is better exhibited by the formula (1) The proportion of the represented repeating unit in all the repeating units is preferably 20 mol% or more as described in claim 2.

  Furthermore, since the polymer flocculant of the invention described in claim 3 contains the chitosan derivative of the invention described in claim 1 as an active ingredient, it has excellent aggregation performance.

〔式中、Ｘは、式(2)：

で表される基を示し、式(2)中のＲ¹は低級アルキレン基、Ｒ²およびＲ³は、同一または異なって、水素原子または低級アルキル基を示す。〕
で表される繰り返し単位を含むことを特徴とするものである。 《Chitosan derivative》
The chitosan derivative of the present invention has the formula (1):

[Wherein X is the formula (2):

In the formula (2), R ¹ is a lower alkylene group, R ² and R ³ are the same or different and each represents a hydrogen atom or a lower alkyl group. ]
It is characterized by including the repeating unit represented by these.

In the chitosan derivative of the present invention, examples of the lower alkylene group corresponding to the group R ¹ include alkylene groups having 1 to 10 carbon atoms such as methylene, ethylene, propylene, butylene, amylene, and hexylene. Among these, ethylene, propylene, and butylene are preferable as the alkylene group having 2 to 4 carbon atoms. Examples of the lower alkyl group corresponding to the groups R ² and R ³ include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, s-butyl, pentyl, hexyl and the like. And an alkyl group having 1 to 10 carbon atoms. Of these, methyl and ethyl are preferable as the alkyl group having 2 or less carbon atoms.

で表される繰り返し単位を含むキトサン、すなわち、β−１，４−ポリ−Ｄ−グルコサミンを改質して合成することができ、原料であるキトサンとしては、従来同様に、式(6)：

で表される繰り返し単位を含むキチン、すなわちβ−１，４−ポリ−Ｎ−アセチル−Ｄ−グルコサミンを、アルカリで処理する等して、脱アセチル化して得られたものを用いることができる。 The chitosan derivative of the present invention has the formula (3):

It is possible to synthesize chitosan containing a repeating unit represented by formula (i), i.e., β-1,4-poly-D-glucosamine, and the chitosan as a raw material is represented by the formula (6):

It is possible to use a product obtained by deacetylating a chitin containing a repeating unit represented by the formula: β-1,4-poly-N-acetyl-D-glucosamine with an alkali or the like.

  Degree of deacetylation of the chitosan, that is, the acetylamino group is deacetylated to form an amino group, and the repeating unit represented by the formula (3) occupies all the repeating units forming the chitosan molecule. The proportion is preferably from 50 to 99 mol%, particularly preferably from 65 to 95 mol%. If the degree of deacetylation of chitosan is less than this range, the water-solubility of the chitosan derivative of the present invention derived from the chitosan may be lowered, or sufficient aggregation performance may not be obtained. Further, in order to increase the degree of deacetylation of chitosan beyond the above range, a high degree of deacetylation treatment is required, and the chitosan derivative of the present invention produced from chitosan and chitosan as a raw material is required. There is a problem in that productivity is lowered and costs are increased.

  The number average molecular weight Mn of chitosan is preferably 50,000 to 1,000,000, and more preferably 100,000 to 700,000. When the number average molecular weight Mn of chitosan is less than this range, the chain length of the chitosan derivative of the present invention synthesized from such chitosan is shortened, and the cohesive force as a polymer chain may be reduced. Moreover, when the number average molecular weight Mn of chitosan exceeds the said range, there exists a possibility that the solubility with respect to acidic aqueous solution of the chitosan derivative of this invention synthesize | combined from this chitosan may fall. Therefore, in any of these cases, there is a possibility that the effect of improving the aggregation performance of the chitosan derivative cannot be obtained sufficiently.

In order to synthesize the chitosan derivative of the present invention represented by the formula (1) from chitosan, as shown in the following reaction process formula, first, in an organic solvent such as dimethylformamide (DMF), the formula ( By reacting chitosan containing the repeating unit represented by 3) with phthalic anhydride represented by the formula (7), the amino group derived from chitosan is replaced with a phthalamide group derived from phthalic anhydride to be protected. Moreover, the 1st intermediate product containing the repeating unit represented by Formula (8) is obtained.

Next, when the first intermediate product is reacted with N, N′-carbonyldiimidazole represented by the formula (9) in an organic solvent such as DMF, the phthalamide group adjoins the first intermediate product. With the —OH group protected (mainly due to steric hindrance), the —OH group at the end of the hydroxymethyl group selectively reacts with the N, N′-carbonyldiimidazole to form an amide ester. As a result, a second intermediate product containing the repeating unit represented by the formula (10) is produced.

〔式中のＲ¹〜Ｒ³は、先に説明したとおりである。〕 Next, the amide ester moiety in the second intermediate product is exchanged with the compound represented by the formula (11) in an organic solvent such as DMF, and the repetition represented by the formula (12) is performed. A third intermediate product containing units is obtained.

[R ^{1 to} R ³ in the formula are as described above. ]

〔式中のＲ¹〜Ｒ³は、先に説明したとおりである。〕 Then, the third intermediate product is reacted with hydrazine hydrate in an organic solvent such as DMF to remove the first reacted phthalamide group, whereby the repeating unit represented by the formula (1) is obtained. Including, the chitosan derivative of the present invention is synthesized.

[R ^{1 to} R ³ in the formula are as described above. ]

  In the chitosan derivative of the present invention synthesized from chitosan based on the above reaction process formula, the proportion of the repeating unit represented by the formula (1) in all repeating units is 20 mol% or more. Is preferred. When the proportion of the repeating unit represented by the formula (1) is less than 20 mol%, the aggregation performance of the chitosan derivative by the three amino groups in the repeating unit represented by the formula (1) described above There is a possibility that the effect of improving the temperature cannot be sufficiently obtained.

  In the chitosan derivative of the present invention, the ratio of the repeating unit represented by the formula (1) is preferably 50% by mole or more even within the above range in consideration of further improving the aggregation performance. . The upper limit of the ratio can be up to 100%. However, in order to make the ratio of the repeating unit represented by the formula (1) 100%, a high degree of treatment is necessary, and the productivity of the chitosan derivative of the present invention is lowered, leading to a cost increase. There is. Therefore, the ratio of the repeating unit represented by the formula (1) is preferably 99 mol% or less, and more preferably 95 mol% or less, even within the above range.

  Since the chitosan derivative of the present invention contains the repeating unit represented by the formula (1) having the above-described molecular structure, its aggregation performance can be improved more than before. Therefore, it can be used satisfactorily as an active ingredient of the polymer flocculant described below.

《Polymer flocculant》
The polymer flocculant of the present invention comprises the chitosan derivative of the present invention as an active ingredient. The polymer flocculant of the present invention may be formed only of the chitosan derivative of the present invention. That is, the chitosan derivative of the present invention may be used as a polymer flocculant as it is (normally in a solid form such as a powder). However, in consideration of improving the handleability, storage stability, etc., it is preferable to provide the chitosan derivative of the present invention as a polymer flocculant in an aqueous solution dissolved in an acidic aqueous solution.

  The concentration of the chitosan derivative in the liquid polymer flocculant is preferably about 0.05 to 0.15 mol / liter in terms of the molar concentration (mol / liter) of the chitosan derivative per liter of the aqueous solution. . Examples of the acid added to the aqueous solution to dissolve the chitosan derivative include organic acids such as acetic acid, oxalic acid, tartaric acid, benzoic acid, and sulfonic acid, and inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. Is preferred. The addition amount of the acid is preferably in a range in which the pH of the aqueous solution can be adjusted to pH 3 to 7 suitable for dissolving the chitosan derivative. The polymer flocculant of the present invention can be used in various applications similar to conventional polymer flocculants such as purification of polluted water and production of raw rubber from natural rubber latex.

<Synthesis of chitosan derivatives>
Under a nitrogen atmosphere, 2 g of powdered chitosan [degree of deacetylation: 95 mol%, number average molecular weight Mn: 700,000] and phthalic anhydride were added to DMF. The amount of phthalic anhydride added was an amount corresponding to 5 mol per mol of the repeating unit represented by the formula (3) that forms chitosan. Next, the mixed liquid containing the above components was heated to 100 ° C. with stirring under reduced pressure for 6 hours, and then cooled with ice water to cause precipitation. The resulting precipitate was separated from the liquid, washed with ethanol, dried, and analyzed by infrared absorption spectroscopy. As shown in the second infrared absorption spectrum from the bottom of FIG. It was confirmed to be the first intermediate product containing the repeating unit represented by 8). The bottom of FIG. 1 is an infrared absorption spectrum of chitosan as a starting material. In FIG. 1, the four infrared absorption spectra including the two infrared absorption spectra are shown side by side. This difference in the upper and lower is the difference in the actual absorption intensity between the infrared absorption spectra. It is not shown. For convenience, the infrared absorption spectra are displayed side by side vertically.

  Next, 0.5 g of the first intermediate product was added to DMF in a nitrogen atmosphere, and the mixture was heated to 100 ° C. with stirring, and N, N′-carbonyldiimidazole was added. The amount of N, N′-carbonyldiimidazole added was assumed that the total amount of the repeating unit represented by the formula (3) in chitosan was changed to the repeating unit of the formula (8) in the previous reaction. Thus, the amount was equivalent to 2 mol per 1 mol of the repeating unit of the formula (8). Next, while stirring, the liquid temperature was maintained at 100 ° C. for 30 minutes, and then the liquid temperature was lowered to 60 ° C. for 2 hours, followed by cooling to cause precipitation. Then, the obtained precipitate was separated from the liquid, washed with acetone, dried, and analyzed by an infrared absorption spectrum method. As shown in the second infrared absorption spectrum from the top of FIG. It was confirmed to be a second intermediate product containing the repeating unit represented by 10).

Next, after adding 0.5 g of the second intermediate product to DMF under a nitrogen atmosphere, the mixture is represented by the formula (11) while being heated to 70 ° C. with stirring under reduced pressure. Along with, N-dimethylamino-ethylamine was added, wherein R ¹ is ethylene and R ² and R ³ are methyl. The amount of N-dimethylamino-ethylamine added is that the total amount of the assumed repeating unit of the formula (8) in the first intermediate product changed to the repeating unit of the formula (10) in the previous reaction. Assuming that the amount is equivalent to 2 mol per 1 mol of the repeating unit of the formula (10). Next, while stirring, the liquid temperature was maintained at 70 ° C. and reacted for 12 hours, followed by cooling to cause precipitation. The obtained precipitate was washed with acetone, dried, and analyzed by infrared absorption spectroscopy. As shown in the first infrared absorption spectrum of FIG. 1, it is represented by the formula (12). It was confirmed to be a third intermediate product containing repeating units.

Next, 0.5 g of the third intermediate product is added to DMF under a nitrogen atmosphere, and the mixture is heated to 100 ° C. with stirring to obtain hydrazine hydrate (N ₂ H ₄ .H ₂ O). added. The amount of hydrated hydrazine added is based on the assumption that the total amount of the repeat unit of formula (10) assumed in the second intermediate product has changed to the repeat unit of formula (12) in the previous reaction. The amount was equivalent to 2 mol per 1 mol of the repeating unit of the formula (12). Next, while stirring, the liquid temperature was maintained at 100 ° C. and reacted for 1 hour, followed by cooling to cause precipitation. The obtained precipitate was washed with acetone and then dried to obtain a reaction product.

The reaction product was analyzed by infrared absorption spectroscopy. The infrared absorption spectrum is shown in FIG. From the figure, the reaction product is a chitosan derivative containing a repeating unit represented by the formula (1), wherein R ¹ in the formula (1) is ethylene, and R ² and R ³ are methyl. confirmed.

<Preparation of polymer flocculant>
0.1 mol of the synthesized chitosan derivative is added to an acidic aqueous solution containing 0.02 mol of acetic acid and dissolved to obtain a liquid polymer flocculant (“polymer flocculant I”) having a concentration of 0.0925 mol / liter. Prepared).

<Experiment 1>
While stirring 20 ml of suspension water having a concentration of 3% by weight containing fine particle clay, the polymer flocculant I was gradually added dropwise to determine the amount required for the fine particle clay to substantially aggregate. It was 6.7 ml. For comparison, 0.1 mol of untreated powdered chitosan [degree of deacetylation: 95 mol%, number average molecular weight Mn: 700,000] was added to an acidic aqueous solution containing 0.02 mol of acetic acid and dissolved. Using the same concentration of liquid polymer flocculant (hereinafter referred to as “polymer flocculant II”) prepared in the same manner, the same test was conducted. The amount of the polymer flocculant II was 10.1 ml.

<Experiment 2>
While stirring 30 ml of fresh natural rubber latex (solid content concentration 30% by weight) within 24 hours after being collected from a rubber tree, the polymer flocculant I is gradually added dropwise to obtain a rubber component. The amount required for substantial aggregation was 0.8 ml. For comparison, when the same test was conducted using the polymer flocculant II, the amount required for the rubber component to substantially aggregate was 2.1 ml. The results of Experiments 1 and 2 are shown in Table 1.

In the Example of this invention, it is a graph which shows the infrared absorption spectrum of the intermediate product produced | generated in the step in the middle of synthesize | combining a chitosan derivative using the chitosan used as a starting material, and the said chitosan. It is a graph which shows the infrared absorption spectrum of the chitosan derivative synthesize | combined in the Example of this invention.

Claims (3)

Formula (1):

[Wherein X is the formula (2):

In the formula (2), R ¹ is a lower alkylene group, R ² and R ³ are the same or different and each represents a hydrogen atom or a lower alkyl group. ]
The chitosan derivative characterized by including the repeating unit represented by these.   The chitosan derivative according to claim 1, which is synthesized from chitosan and the proportion of the repeating unit represented by the formula (1) in all repeating units is 20 mol% or more. A polymer flocculant comprising the chitosan derivative according to claim 1 or 2 as an active ingredient.

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