JP5540319B2 - Synthesis method of biodegradable superabsorbent polymer - Google Patents

Synthesis method of biodegradable superabsorbent polymer Download PDF

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JP5540319B2
JP5540319B2 JP2010149142A JP2010149142A JP5540319B2 JP 5540319 B2 JP5540319 B2 JP 5540319B2 JP 2010149142 A JP2010149142 A JP 2010149142A JP 2010149142 A JP2010149142 A JP 2010149142A JP 5540319 B2 JP5540319 B2 JP 5540319B2
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裕之 甲野
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Description

本発明は、生分解性を持つ高吸水性高分子の合成方法および該合成方法により得られる生分解性高吸水性高分子に関するものである。   The present invention relates to a method for synthesizing a biodegradable superabsorbent polymer and a biodegradable superabsorbent polymer obtained by the synthesis method.

高吸水性高分子はその高い吸水性と保水性から衛生用品をはじめ、農業・園芸、流通資材、土木・建築、医療、トイレタリーまで幅広い活用がされている。歴史的にはまだ企業化が始められてから僅か25年程度であるが、衛生材料を中心として大きな市場が形成されており、その国内市場規模50万トン、750億円といわれている。   Highly water-absorbing polymers are widely used for hygiene products, agriculture / horticulture, distribution materials, civil engineering / architecture, medical care, toiletries, etc. due to their high water absorption and water retention. Historically, it has only been about 25 years since the start of commercialization, but a large market has been formed centering on sanitary materials, and the domestic market size is said to be 500,000 tons and 75 billion yen.

高吸水性高分子の合成には、一般的に原油から精製されるポリアクリル酸ナトリウム架橋体などアクリル酸系樹脂などを原料として用いられることが多い。しかしながらアクリル酸系は難分解性であるので、紙おむつなどに使用した場合、廃棄後これらが環境中に分散すれば環境問題を引き起こすことが懸念されている。そこで近年、生分解性を有する高吸水性高分子の開発が行われてきている。   For synthesizing a superabsorbent polymer, acrylic resin such as sodium polyacrylate crosslinked from crude oil is generally used as a raw material. However, since acrylic acid-based materials are hardly decomposable, there is a concern that when used in disposable diapers or the like, if they are dispersed in the environment after disposal, environmental problems may be caused. Therefore, in recent years, development of superabsorbent polymers having biodegradability has been performed.

生分解性を有し、かつ吸水力に優れた材料として、セルロース誘導体を利用することが試みられており、特にカルボン酸塩を構造中に含むカルボキシメチルセルロースを用いて検討されてきた。例えばカルボキシメチルセルロースを化学的に架橋する方法(特許文献1〜4)、放射線架橋を用いて自己架橋する方法(特許文献5)が知られている。   As a material having biodegradability and excellent water absorption, attempts have been made to use cellulose derivatives. In particular, studies have been made using carboxymethyl cellulose containing a carboxylate in its structure. For example, a method of chemically crosslinking carboxymethyl cellulose (Patent Documents 1 to 4) and a method of self-crosslinking using radiation crosslinking (Patent Document 5) are known.

しかし、上記技術では、いずれもセルロース誘導体を出発物質として使用し、製造コストの点で問題が残る。また架橋部とカルボキシメチルセルロース間の結合はエーテル結合であり、化学的に安定なため、生分解性の点でも問題がある。   However, any of the above techniques uses a cellulose derivative as a starting material, and there remains a problem in terms of production cost. In addition, the bond between the cross-linked portion and carboxymethylcellulose is an ether bond, and is chemically stable, so there is a problem in terms of biodegradability.

一方、セルロースそのものを、エーテル結合ではなく高い生分解性を示すエステル結合で架橋する方法として、コハク酸無水物を用いる方法が開示されているが(非特許文献1)、得られる吸水性材料中に含まれるカルボン酸ナトリウム塩の含有量が少ないため、吸水速度が遅いものしか得られないという問題がある。   On the other hand, although a method using succinic anhydride is disclosed as a method of crosslinking cellulose itself with an ester bond exhibiting high biodegradability rather than an ether bond (Non-patent Document 1), Since the content of sodium carboxylate contained in is small, there is a problem that only those having a low water absorption rate can be obtained.

特開2006−188697号公報JP 2006-188867 A 特開平7−82301号公報JP-A-7-82301 特開平9−850807号公報Japanese Patent Laid-Open No. 9-850807 特開2004−137382号公報JP 2004-137382 A 特開2001−2703号公報JP 2001-2703 A

Yoshimura et al, J. Appl. Polym. Sci. 99, 3251-3256 (2006)Yoshimura et al, J. Appl. Polym. Sci. 99, 3251-3256 (2006)

そこで本発明で解決すべき課題は、ポリアクリル酸ナトリウム架橋体の代替材料として、天然に大量に存在するセルロース、キチン、キトサン等を原料として、生分解性が高く、かつ吸水力や吸水速度も既存のアクリル酸系樹脂を用いたものに匹敵しうる環境に優しい高吸水性高分子の合成方法、および該合成方法により得られる生分解性高吸水性高分子を提供することにある。   Therefore, the problem to be solved by the present invention is that, as an alternative material for a crosslinked poly (sodium acrylate), natural biodegradable cellulose, chitin, chitosan, etc. are used as raw materials, and the biodegradability is high, and the water absorption power and water absorption speed are An object is to provide a method for synthesizing an environment-friendly superabsorbent polymer comparable to that using an existing acrylic acid resin, and a biodegradable superabsorbent polymer obtained by the synthesis method.

上記課題を解決するため、本発明の生分解性高吸水性高分子では、セルロース、キチン、キトサンおよび多糖類の群から選ばれる1以上の天然由来高分子を、ポリカルボン酸無水物を用いてエステル架橋反応させる工程を含むことを最も主要な特徴とする。   In order to solve the above problems, in the biodegradable superabsorbent polymer of the present invention, one or more naturally-derived polymers selected from the group consisting of cellulose, chitin, chitosan and polysaccharides are obtained using polycarboxylic acid anhydrides. The main feature is that it includes a step of ester crosslinking reaction.

本発明の合成方法によれば、天然高分子であるセルロース、キチン、キトサン等を出発原料とするので、環境への負担が少ない。さらに、高い生分解性を有するので、廃棄による環境負担も少ない。加えて、本発明の合成方法では、安価なポリカルボン酸無水物を用いてエステル架橋反応させることができるので、コスト面でも有利である。   According to the synthesis method of the present invention, natural polymers such as cellulose, chitin, chitosan, and the like are used as starting materials, so the burden on the environment is small. Furthermore, since it has high biodegradability, there is little environmental burden due to disposal. In addition, in the synthesis method of the present invention, an ester crosslinking reaction can be performed using an inexpensive polycarboxylic anhydride, which is advantageous in terms of cost.

その一方、本発明の合成方法で得られる生分解性高吸水性高分子の吸水性能や保水性能は、既存の石油を原料としたアクリル酸系樹脂のものと同等、もしくはそれ以上の性能を示すことから、環境調和型の代替材料としての利用価値が高い。   On the other hand, the water absorption performance and water retention performance of the biodegradable superabsorbent polymer obtained by the synthesis method of the present invention are equivalent to or better than those of acrylic resins based on existing petroleum. Therefore, the utility value as an environmentally friendly alternative material is high.

本発明の合成方法の例を示す製造フロー図である。It is a manufacturing flowchart which shows the example of the synthetic | combination method of this invention. 本発明で合成される生分解性高吸水性高分子の製品概要である。(a)は既存市販品であり、(b)は本発明品である。It is a product outline of the biodegradable superabsorbent polymer synthesized by the present invention. (A) is an existing commercial product, and (b) is the product of the present invention. 図2の生分解性高吸水性高分子を吸水させた30秒後の製品概要である。(a)は既存市販品であり、(b)は本発明品である。It is the product outline | summary 30 seconds after water-absorbing the biodegradable superabsorbent polymer of FIG. (A) is an existing commercial product, and (b) is the product of the present invention. 本発明で合成される生分解性高吸水性高分子の吸水速度−吸水量チャートである(ポリカルボン酸無水物の反応当量倍数依存性)。It is a water absorption speed-water absorption amount chart of the biodegradable highly water-absorbing polymer synthesized in the present invention (depending on the reaction equivalent multiple of polycarboxylic acid anhydride). 本発明で合成される生分解性高吸水性高分子の吸水速度−吸水量チャートである(溶媒の比較)。It is a water absorption speed-water absorption amount chart of the biodegradable superabsorbent polymer synthesized in the present invention (comparison of solvents). 本発明で合成される生分解性高吸水性高分子の吸水速度−吸水量チャートである(セルロース重合度の比較)。It is a water absorption rate-water absorption amount chart of the biodegradable superabsorbent polymer synthesized in the present invention (comparison of cellulose polymerization degree). 本発明で合成される生分解性高吸水性高分子の保水率の経時変化を示すチャートである。It is a chart which shows the time-dependent change of the water retention of the biodegradable superabsorbent polymer synthesized by the present invention. 本発明で合成される生分解性高吸水性高分子の吸水速度−吸水量チャートである(原材料脱脂綿,反応当量倍数の比較)。It is a water absorption rate-water absorption amount chart of the biodegradable superabsorbent polymer synthesized in the present invention (raw material absorbent cotton, comparison of reaction equivalent multiples). 本発明で合成される生分解性高吸水性高分子の吸水速度−吸水量チャートである(原材料キチン-BTCA(溶媒LiCl/NMP),反応当量倍数の比較)。It is a water absorption rate-water absorption amount chart of the biodegradable superabsorbent polymer synthesized in the present invention (raw material chitin-BTCA (solvent LiCl / NMP), comparison of reaction equivalent multiples). 本発明で合成される生分解性高吸水性高分子の吸水速度−吸水量チャートである(原材料キチン-BTCA(溶媒TBAF/DMSO),反応当量倍数の比較)。It is a water absorption rate-water absorption chart of the biodegradable superabsorbent polymer synthesized in the present invention (raw material chitin-BTCA (solvent TBAF / DMSO), comparison of reaction equivalent multiples). 本発明で合成される生分解性高吸水性高分子の吸水速度−吸水量チャートである(原材料キチン-DSDA,反応当量倍数の比較)。It is a water absorption rate-water absorption amount chart of the biodegradable superabsorbent polymer synthesized in the present invention (raw material chitin-DSDA, comparison of reaction equivalent multiples). 本発明で合成される生分解性高吸水性高分子の吸水速度−吸水量チャートである(原材料キトサン,反応当量倍数の比較)。It is a water absorption rate-water absorption amount chart of the biodegradable superabsorbent polymer synthesized in the present invention (comparison of raw material chitosan and reaction equivalent multiple).

図1には、天然由来高分子としてセルロースを出発原料とした場合の本発明を実施するための合成フローを示した。まず、出発原料であるセルロースを、塩化リチウム(LiCl)/N,N,-ジメチルアセトアミド(DMAc)、LiCl/N-メチルピロリドン(NMP)、フッ化テトラブチルアンモニウム(TBAF)/ジメチルスルホキシド(DMSO)のいずれかに溶解させ、室温・常圧下においてN,N-ジメチル-4-アミノピリジン(DMAP)を触媒としてポリカルボン酸無水物とエステル架橋反応を行う。ポリカルボン酸無水物としては1,2,3,4-ブタンテトラカルボン酸二無水物(BTCA)、もしくは3,3',4,4'-ジフェニルスルホンテトラカルボン酸二無水物(DSDA)が望ましい。このエステル架橋反応によって、セルロースの水酸基とカルボン酸無水物間でエステル化が進行し、セルロース分子鎖間でエステル性架橋が形成されると同時に、カルボン酸無水物はカルボキシル基に変換される。   FIG. 1 shows a synthesis flow for carrying out the present invention when cellulose is used as a naturally occurring polymer as a starting material. First, cellulose as the starting material is mixed with lithium chloride (LiCl) / N, N, -dimethylacetamide (DMAc), LiCl / N-methylpyrrolidone (NMP), tetrabutylammonium fluoride (TBAF) / dimethylsulfoxide (DMSO) Then, an ester crosslinking reaction is carried out with polycarboxylic acid anhydride using N, N-dimethyl-4-aminopyridine (DMAP) as a catalyst at room temperature and normal pressure. The polycarboxylic acid anhydride is preferably 1,2,3,4-butanetetracarboxylic dianhydride (BTCA) or 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA) . By this ester crosslinking reaction, esterification proceeds between the hydroxyl group of the cellulose and the carboxylic acid anhydride, and esteric crosslinking is formed between the cellulose molecular chains. At the same time, the carboxylic acid anhydride is converted into a carboxyl group.

前記エステル架橋反応で得られた反応物をメタノール、アセトンなどの有機溶媒に沈殿させ、塩基性水溶液によってpH7になるまで中和を行う。この中和反応により、生成したカルボキシル基は、カルボン酸塩へ変換される。これら操作によって、吸水性の役割を果たすカルボン酸塩と、保水性の役割を果たすエステル性架橋された三次元架橋構造とを持つ生分解性高吸水性高分子が得られる。架橋セルロース、架橋キチンの吸水・保水性能は、ポリカルボン酸架橋密度に依存するため、ポリカルボン酸無水物の仕込濃度、反応溶媒、原料であるセルロースの重合度などを制御することで様々な用途に適した特性を持つ生分解性高吸水性高分子を得ることが可能である。   The reaction product obtained by the ester cross-linking reaction is precipitated in an organic solvent such as methanol and acetone, and neutralized with a basic aqueous solution until pH 7 is reached. By this neutralization reaction, the produced carboxyl group is converted into a carboxylate. By these operations, a biodegradable superabsorbent polymer having a carboxylate that plays a role in water absorption and an esterically crosslinked three-dimensional cross-linked structure that plays a role in water retention is obtained. The water absorption and water retention performance of cross-linked cellulose and cross-linked chitin depends on the cross-link density of polycarboxylic acid, so it can be used in various applications by controlling the concentration of polycarboxylic acid anhydride, reaction solvent, polymerization degree of cellulose as raw material, etc. It is possible to obtain a biodegradable superabsorbent polymer having characteristics suitable for the above.

出発原料としては、セルロースの他に、キチン、キトサン、またはアミロースなどの多糖類、さらにはこれらの混合物を用いても同様の性能を持つ生分解性高吸水性高分子を得ることができる。ただし出発原料としてキトサンや多糖類を用いる場合は、溶媒として酸水溶液と有機溶媒の混合系、例えば10%酢酸水溶液/メタノール/NMPの1:1:1混合溶媒などを用いて行うことができる。なかでも綿のセルロースなど、重合度1500以上のセルロースを用いることで、現行市販品と同等以上の吸水性能を持つ生分解性高吸水性高分子が得られるので好ましい。   As a starting material, a biodegradable superabsorbent polymer having the same performance can be obtained by using polysaccharides such as chitin, chitosan, amylose, and mixtures thereof in addition to cellulose. However, when chitosan or a polysaccharide is used as a starting material, it can be carried out using a mixed system of an acid aqueous solution and an organic solvent, for example, a 1: 1: 1 mixed solvent of 10% aqueous acetic acid / methanol / NMP as a solvent. In particular, it is preferable to use cellulose having a polymerization degree of 1500 or more, such as cotton cellulose, because a biodegradable superabsorbent polymer having a water absorption performance equal to or higher than that of the current commercial product can be obtained.

以下、実施例により本発明をさらに詳しく説明するが、本発明の合成方法は、実施例記載の様態のみに限られるものではない。下記実施例1〜7の合成条件の概要をまとめて表1に示した。また下記実施例8〜12の概要をまとめて表2に示した。   Hereinafter, the present invention will be described in more detail with reference to examples. However, the synthesis method of the present invention is not limited to the modes described in the examples. Table 1 summarizes the synthesis conditions of Examples 1 to 7 below. The outline of Examples 8 to 12 below is summarized in Table 2.

(A.出発原料:セルロース)
下記実施例1〜10の合成条件の概要をまとめて表1に示した。また下記実施例11〜15の概要をまとめて表2に示した。
(A. Starting material: cellulose)
Table 1 summarizes the synthesis conditions of Examples 1 to 10 below. The outline of Examples 11 to 15 below is summarized in Table 2.

〔実施例1〕
NMP100 mLにLiCl5gを溶解した溶媒に、セルロースとしてパルプ(平均重合度:800)0.5g(グルコース換算で3.1mmol)を添加し、完全に溶解するまで攪拌した。その後、塩基性触媒であるDMAP 1.19 g(9.7mmmol)とBTCA 2.3g(11.6mmol)を加え、室温下で攪拌し、架橋反応を行わせた。
[Example 1]
To a solvent in which 5 g of LiCl was dissolved in 100 mL of NMP, 0.5 g (3.1 mmol in terms of glucose) of pulp (average polymerization degree: 800) was added as cellulose and stirred until it was completely dissolved. Thereafter, 1.19 g (9.7 mmol) of DMAP as a basic catalyst and 2.3 g (11.6 mmol) of BTCA were added, and the mixture was stirred at room temperature to cause a crosslinking reaction.

セルロースは、架橋点としてグルコース単位あたり3つの水酸基を持つ。一方、1,2,3,4-ブタンテトラカルボン酸二無水物は、加水分解によって、1,2,3,4-ブタンテトラカルボン酸になり、架橋点として1分子あたり2つのカルボキシル基を持つ。したがって反応の当量は、セルロースのグルコース1単位:BTCA=3:2である。以上より、実施例1におけるセルロースのグルコース1単位あたりに対するBTCAの反応当量倍数(以下、単に「ポリカルボン酸無水物の反応当量倍数」或いは「反応当量倍数」という場合がある。)を求めると 2×11.6mmol/3×3.1 mmol= 2.5倍となる。   Cellulose has three hydroxyl groups per glucose unit as a crosslinking point. On the other hand, 1,2,3,4-butanetetracarboxylic dianhydride becomes 1,2,3,4-butanetetracarboxylic acid by hydrolysis and has two carboxyl groups per molecule as a crosslinking point. . Therefore, the equivalent of reaction is 1 unit of glucose of cellulose: BTCA = 3: 2. From the above, the reaction equivalent multiple of BTCA per unit of glucose of cellulose in Example 1 (hereinafter sometimes simply referred to as “reaction equivalent multiple of polycarboxylic acid anhydride” or “reaction equivalent multiple”) 2 is obtained. X 11.6 mmol / 3 x 3.1 mmol = 2.5 times.

架橋反応の後、24時間室温で放置した後200mLのメタノールに中に注ぐことで架橋セルロースを析出させた。析出物に10% 水酸化ナトリウムを滴下し、pH7の中性にしてカルボキシル基をカルボン酸ナトリウム塩へ変換させた。生じた沈殿をろ過、乾燥することによって、白色繊維状である実施例1の生分解性高吸水性材料が得られた。   After the crosslinking reaction, the mixture was allowed to stand at room temperature for 24 hours and then poured into 200 mL of methanol to precipitate crosslinked cellulose. To the precipitate, 10% sodium hydroxide was added dropwise to neutralize the pH to convert the carboxyl group to a carboxylic acid sodium salt. The resulting precipitate was filtered and dried to obtain a biodegradable superabsorbent material of Example 1 which was white fibrous.

(合成物評価)
図2(b)では、実施例1で合成された生分解性高吸水性高分子の概要を示した。図3(b)では、図2(b)で示した生分解性高吸水性高分子に吸水させた30秒後の写真を示す。比較のため、図2(a),図3(a)では、ポリアクリル酸ナトリウム架橋体の既存市販品であるサンダイヤポリマー株式会社製「サンウエット」(登録商標)(注:以下の実施例における既存市販品の評価で同じ。)の写真を示した。このように、実施例1で合成された生分解性高吸水性高分子は、水が存在すれば瞬時に吸水し、透明なハイドロゲルへと変化する。また市販品であるポリアクリル酸ナトリウム架橋体は、30秒後の吸水量が、乾燥時における自重の120倍であるのに対して、実施例1で合成された生分解性高吸水性高分子は、30秒後の吸水量が、乾燥時における自重の136倍という優れた初期吸水速度を示した。また流動性が低いという利点も併せ持つことが分かった。
(Composite evaluation)
FIG. 2B shows an outline of the biodegradable superabsorbent polymer synthesized in Example 1. FIG. 3 (b) shows a photograph 30 seconds after the biodegradable superabsorbent polymer shown in FIG. 2 (b) has absorbed water. For comparison, in FIG. 2 (a) and FIG. 3 (a), “Sunwet” (registered trademark) manufactured by Sundia Polymer Co., Ltd., which is an existing commercial product of a sodium polyacrylate crosslinked product (Note: in the following examples) The same picture is shown for evaluation of existing commercial products). Thus, the biodegradable superabsorbent polymer synthesized in Example 1 absorbs water instantaneously if water is present, and changes to a transparent hydrogel. The commercially available sodium polyacrylate cross-linked product has a water absorption after 30 seconds of 120 times its own weight during drying, whereas the biodegradable superabsorbent polymer synthesized in Example 1 The water absorption after 30 seconds showed an excellent initial water absorption rate of 136 times its own weight during drying. It was also found to have the advantage of low fluidity.

〔実施例2〜5〕
BTCAの仕込量を変化させて、得られる生分解性高吸水性高分子について、最大吸水量に関するポリカルボン酸無水物の反応当量倍数依存性を調べた。原材料であるBTCAの配合量をそれぞれ、〔実施例2〕0.46g (2.32mmol)、〔実施例3〕0.92 (4.64 mmol)、〔実施例4〕4.6g (23.2 mmol)、〔実施例5〕6.9g (34.8 mmol)に替えた以外は実施例1と同じ合成条件で、実施例2〜5の生分解性高吸水性高分子を得た。各実施例の反応当量倍数は、〔実施例2〕0.5倍、〔実施例3〕1.0倍、〔実施例4〕5.0倍、〔実施例5〕7.5倍である。
[Examples 2 to 5]
By varying the amount of BTCA charged, the biodegradable superabsorbent polymer obtained was examined for the reaction equivalent multiple dependence of the polycarboxylic acid anhydride on the maximum water absorption. The blending amounts of the raw materials BTCA are [Example 2] 0.46 g (2.32 mmol), [Example 3] 0.92 (4.64 mmol), [Example 4] 4.6 g (23.2 mmol), and [Example 5]. The biodegradable superabsorbent polymer of Examples 2-5 was obtained on the same synthesis conditions as Example 1 except having replaced with 6.9g (34.8 mmol). The reaction equivalent multiple of each example is [Example 2] 0.5 times, [Example 3] 1.0 times, [Example 4] 5.0 times, and [Example 5] 7.5 times.

(合成物評価)
図4には、実施例1〜6の生分解性高吸水性高分子と、比較のため既存市販品との吸水速度−吸水量チャートを示した。図4中の各実施例の吸水速度−吸水量曲線付近に示した数値は、各実施例の架橋度を示す。図4中のカッコ内はポリカルボン酸無水物の反応当量倍数を示す。この結果、ポリカルボン酸無水物の反応当量倍数が2.5倍〔実施例1〕のときに、50時間経過後吸水量が、乾燥時における自重の300倍の最大吸水量という最も高い値を示した。このときの架橋度は0.49であり、セルロースを構成するグルコース1残基あたり、0.5個のBTCAが架橋されることが望ましいことが分かった。
(Composite evaluation)
FIG. 4 shows a water absorption rate-water absorption amount chart of the biodegradable superabsorbent polymers of Examples 1 to 6 and existing commercial products for comparison. The numerical values shown in the vicinity of the water absorption rate-water absorption amount curve in each example in FIG. 4 indicate the degree of crosslinking in each example. The numbers in parentheses in FIG. 4 indicate the reaction equivalent multiple of the polycarboxylic acid anhydride. As a result, when the reaction equivalent multiple of the polycarboxylic acid anhydride was 2.5 times [Example 1], the water absorption after 50 hours showed the highest value of the maximum water absorption of 300 times its own weight during drying. . The degree of crosslinking at this time was 0.49, and it was found that 0.5 BTCA is desirably crosslinked per glucose residue constituting cellulose.

〔実施例6〕
反応溶媒をLiCl/NMPからLiCl/DMAcに替えて得られる生分解性高吸水性高分子の溶媒依存性を調べた。ただしLiCl/DMAc系では、セルロースは室温で溶解しないので、下記手順で調製を行った。
Example 6
The solvent dependence of the biodegradable superabsorbent polymer obtained by changing the reaction solvent from LiCl / NMP to LiCl / DMAc was investigated. However, in the LiCl / DMAc system, since cellulose does not dissolve at room temperature, it was prepared according to the following procedure.

DMAc 100 mLにLiCl 5gを溶解した溶媒に、セルロースとしてパルプ(平均重合度:800)0.5gを添加し、150℃、1時間攪拌することで、セルロースを完全に溶解した。その後、室温にし、塩基性触媒であるDMAP 1.19 g(9.7mmmol)とBTCA 2.3g(11.6mmol)を加え、室温下で攪拌し、架橋反応を行わせた。なお、この系におけるポリカルボン酸無水物の反応当量倍数は2.5倍である。架橋反応後の操作は、実施例1と記載の手順で行い、実施例6の生分解性高吸水性高分子を得た。   To a solvent obtained by dissolving 5 g of LiCl in 100 mL of DMAc, 0.5 g of pulp (average polymerization degree: 800) as cellulose was added and stirred at 150 ° C. for 1 hour to completely dissolve the cellulose. Thereafter, the mixture was brought to room temperature, 1.19 g (9.7 mmol) of DMAP as a basic catalyst and 2.3 g (11.6 mmol) of BTCA were added, and the mixture was stirred at room temperature to carry out a crosslinking reaction. The reaction equivalent multiple of the polycarboxylic acid anhydride in this system is 2.5 times. The operation after the crosslinking reaction was performed according to the procedure described in Example 1, and the biodegradable superabsorbent polymer of Example 6 was obtained.

(合成物評価)
実施例6で得られた生分解性高吸水性高分子と、比較のため、実施例1で得られた生分解性高吸水性高分子および既存市販品について、市販のポリアクリル酸ナトリウムの高吸水性高分子と比較して、吸水速度-吸水量特性を調べた。その結果を図5に示した。図5中のカッコ内は溶媒の種類を示す。その結果、反応溶媒としてLiCl/DMAcを用いることで、150時間経過後の吸水量が乾燥時における自重の700倍に向上することが分かった。
(Composite evaluation)
For comparison with the biodegradable superabsorbent polymer obtained in Example 6 and the biodegradable superabsorbent polymer obtained in Example 1 and existing commercial products, a high level of commercially available sodium polyacrylate was used. Compared with the water-absorbing polymer, the water absorption speed-water absorption characteristics were investigated. The results are shown in FIG. The parentheses in FIG. 5 indicate the type of solvent. As a result, it was found that by using LiCl / DMAc as the reaction solvent, the water absorption after 150 hours was improved to 700 times its own weight during drying.

〔実施例7〕
原料セルロースとして、パルプから脱脂綿(平均重合度:12,000)に替えた以外は実施例1と同じ合成条件で、実施例7の生分解性高吸水性高分子を得た。
Example 7
The biodegradable superabsorbent polymer of Example 7 was obtained under the same synthesis conditions as Example 1 except that the raw material cellulose was changed from pulp to absorbent cotton (average degree of polymerization: 12,000).

(合成物評価)
実施例7で得られた脱脂綿を原料とする生分解性高吸水性高分子について、実施例3のパルプを原料とするポリアクリル酸ナトリウムの高吸水性高分子および既存市販品と比較して、吸水速度-吸水量特性を調べた。その結果を図6に示した。図5中のカッコ内はセルロースの平均重合度を示す。その結果、重合度が高い脱脂綿が良好な結果を示し、150時間経過後の吸水量が乾燥時における自重の720倍に向上することが分かった。また実施例7の生分解性高吸水性高分子と、比較のため既存市販品との保水曲線を図7に示す。実施例7の生分解性高吸水性高分子は、既存市販品であるポリアクリル酸ナトリウム架橋体よりも高い保水性能を示し、25℃、湿度20%環境下での保水率は85%/日であった。
(Composite evaluation)
About the biodegradable superabsorbent polymer using the absorbent cotton obtained in Example 7 as a raw material, compared with the superabsorbent polymer of sodium polyacrylate using the pulp of Example 3 as a raw material and existing commercial products, The water absorption speed-water absorption characteristics were investigated. The results are shown in FIG. The values in parentheses in FIG. 5 indicate the average degree of polymerization of cellulose. As a result, absorbent cotton having a high degree of polymerization showed good results, and it was found that the water absorption after 150 hours was improved to 720 times its own weight during drying. Moreover, the water retention curve of the biodegradable superabsorbent polymer of Example 7 and the existing commercial product is shown in FIG. 7 for comparison. The biodegradable superabsorbent polymer of Example 7 shows higher water retention performance than the existing sodium polyacrylate cross-linked product, and the water retention rate at 25 ° C. and 20% humidity is 85% / day. Met.

〔実施例8〜10〕
原料セルロースとして、パルプから脱脂綿(平均重合度:12,000)に替えた以外は実施例6と同じ合成条件で、実施例8の生分解性高吸水性高分子を得た。また原材料であるBTCAの配合量をそれぞれ〔実施例9〕0.92g (4.64 mmol)、〔実施例10〕4.6 g(23.2 mmol)に替えた以外は実施例8と同じ合成条件で、実施例9,10の生分解性高吸水性高分子を得た。各実施例の反応当量倍数は、〔実施例8〕2.5倍、〔実施例9〕1.0倍、〔実施例10〕5.0倍である。
[Examples 8 to 10]
The biodegradable superabsorbent polymer of Example 8 was obtained under the same synthesis conditions as in Example 6 except that the raw material cellulose was changed from pulp to absorbent cotton (average polymerization degree: 12,000). In addition, Example 9 was prepared under the same synthesis conditions as Example 8, except that the amount of BTCA as a raw material was changed to [Example 9] 0.92 g (4.64 mmol) and [Example 10] 4.6 g (23.2 mmol), respectively. , 10 biodegradable superabsorbent polymers were obtained. The reaction equivalent multiple of each Example is [Example 8] 2.5 times, [Example 9] 1.0 times, and [Example 10] 5.0 times.

(合成物評価)
実施例8〜10で得られた脱脂綿を原料とし、LiCl/ DMAc系を溶媒とした生分解性高吸水性高分子について、吸水速度−吸水量特性を調べた。表3には、実施例8〜10の生分解性高吸水性高分子について、吸水時間ごとの吸水量の反応当量倍数依存性を示した。また図8には、実施例8〜10の生分解性高吸水性高分子の吸水速度−吸水量チャートを示した。図8中のカッコ内はポリカルボン酸無水物の反応当量倍数を示す。この結果、ポリカルボン酸無水物の反応当量倍数が1.0倍〔実施例9〕のときに、48時間経過後吸水量が、乾燥時における自重の1045倍,ポリカルボン酸無水物の反応当量倍数が5.0倍〔実施例10〕のときに、48時間経過後吸水量が、乾燥時における自重の953倍という高い値を示した。このように、BTCAの割合が増えると、吸水率が一度下がって〔実施例8〕、その後吸水率が上がる挙動を示す原因は必ずしも定かではないが、BTCA濃度が増加すると、最初に架橋反応が優先して進行し、その後グラフト(枝分かれ)構造が生じているためではないかと推測される。
(Composite evaluation)
With respect to the biodegradable superabsorbent polymer using the absorbent cotton obtained in Examples 8 to 10 as a raw material and using a LiCl / DMAc system as a solvent, the water absorption rate-water absorption characteristics were examined. Table 3 shows the reaction equivalent multiple dependence of the amount of water absorption for each water absorption time for the biodegradable superabsorbent polymers of Examples 8 to 10. FIG. 8 shows a water absorption rate-water absorption amount chart of the biodegradable superabsorbent polymers of Examples 8 to 10. The numbers in parentheses in FIG. 8 indicate the reaction equivalent multiple of the polycarboxylic acid anhydride. As a result, when the reaction equivalent multiple of the polycarboxylic acid anhydride was 1.0 times [Example 9], the water absorption after 48 hours was 1045 times its own weight during drying, and the reaction equivalent multiple of the polycarboxylic anhydride was At 5.0 times [Example 10], the water absorption after 48 hours showed a high value of 953 times its own weight during drying. As described above, when the ratio of BTCA increases, the water absorption rate decreases once [Example 8], and the cause of the behavior in which the water absorption rate increases thereafter is not necessarily clear. However, when the BTCA concentration increases, the crosslinking reaction first occurs. It is presumed that this is because it progresses preferentially and then a graft (branched) structure is formed.

〔実施例11〜15〕
反応溶媒をNMP100 mLにLiCl5gを溶解した溶媒から、DMSO 85 mLにTBAF 15gを溶解した溶媒に替えた以外は実施例1と同じ合成条件で、実施例11の生分解性高吸水性高分子を得た。また原材料であるBTCAの配合量をそれぞれ、〔実施例12〕0.46g (2.32mmol)、〔実施例13〕0.92 (4.64 mmol)、〔実施例14〕4.6g (23.2 mmol)、〔実施例15〕6.9g (34.8 mmol)に替えた以外は実施例11と同じ合成条件で、実施例12〜15の生分解性高吸水性高分子を得た。各実施例の反応当量倍数は、〔実施例11〕2.5倍、〔実施例12〕0.5倍、〔実施例13〕1.0倍、〔実施例14〕5.0倍、〔実施例15〕7.5倍である。
[Examples 11 to 15]
The biodegradable superabsorbent polymer of Example 11 was prepared under the same synthesis conditions as in Example 1 except that the reaction solvent was changed from a solvent in which 5 g of LiCl was dissolved in 100 mL of NMP to a solvent in which 15 g of TBAF was dissolved in 85 mL of DMSO. Obtained. Moreover, the compounding quantity of BTCA which is a raw material is [Example 12] 0.46 g (2.32 mmol), [Example 13] 0.92 (4.64 mmol), [Example 14] 4.6 g (23.2 mmol), [Example 15], respectively. The biodegradable superabsorbent polymers of Examples 12 to 15 were obtained under the same synthesis conditions as in Example 11 except that the amount was changed to 6.9 g (34.8 mmol). The reaction equivalent multiple of each example is [Example 11] 2.5 times, [Example 12] 0.5 times, [Example 13] 1.0 times, [Example 14] 5.0 times, and [Example 15] 7.5 times. .

(合成物評価)
表4には、実施例11〜15の生分解性高吸水性高分子について、吸水時間ごとの吸水量の反応当量倍数依存性を示した。この結果、ポリカルボン酸無水物の反応当量倍数が1.0倍〔実施例13〕のときに、48時間経過後吸水量が、乾燥時における自重の925倍の最大吸水量という最も高い値を示した。
(Composite evaluation)
Table 4 shows the reaction equivalent multiple dependency of the water absorption amount for each water absorption time for the biodegradable superabsorbent polymers of Examples 11 to 15. As a result, when the reaction equivalent multiple of the polycarboxylic acid anhydride was 1.0 times (Example 13), the water absorption after 48 hours showed the highest value of the maximum water absorption of 925 times its own weight during drying. .

以上のセルロースを出発原料とする実施例から、最適な条件としてLiCl/DMAcを溶媒として、綿のセルロースのような重合度の高いセルロースを使用して合成した場合に、得られる生分解性高吸水性高分子の吸水量が、よりいっそう向上することが分かった。   From the above examples using cellulose as a starting material, the biodegradable high water absorption obtained when synthesized using cellulose having a high degree of polymerization such as cotton cellulose using LiCl / DMAc as a solvent under optimum conditions It has been found that the water absorption of the functional polymer is further improved.

(B.出発原料:キチン)
下記実施例16〜25の合成条件の概要をまとめて表5に示した。また下記実施例26〜29の合成条件の概要をまとめて表6に示した。
(B. Starting material: chitin)
Table 5 summarizes the synthesis conditions of Examples 16 to 25 below. Table 6 summarizes the synthesis conditions of Examples 26 to 29 below.

〔実施例16〕
NMP100 mLにLiCl5gを溶解した溶媒に、キチン(α‐キチン(Sigma社製)アセチル化度:84%(脱アセチル化度16%)分子量分布:5×105〜2×106)0.63g(N-アセチルグルコサミン換算で3.1mmol)を添加し、完全に溶解するまで攪拌した。その後、塩基性触媒である0.79g(6.4mmol)とBTCA 0.60g(3.1mmol)を加え、室温下で攪拌し、架橋反応を行わせた。架橋反応後の操作は、実施例1に記載の手順で行い、実施例16の生分解性高吸水性高分子を得た。
Example 16
In a solvent in which 5 g of LiCl was dissolved in 100 mL of NMP, chitin (α-chitin (manufactured by Sigma)) acetylation degree: 84% (deacetylation degree 16%), molecular weight distribution: 5 × 105 to 2 × 106) 0.63 g (N- 3.1 mmol) in terms of acetylglucosamine was added and stirred until completely dissolved. Thereafter, 0.79 g (6.4 mmol) as a basic catalyst and 0.60 g (3.1 mmol) of BTCA were added, and the mixture was stirred at room temperature to cause a crosslinking reaction. The operation after the crosslinking reaction was performed according to the procedure described in Example 1 to obtain the biodegradable superabsorbent polymer of Example 16.

キチンは、架橋点としてN−アセチルグルコサミン残基あたり、2つの水酸基を持つ。一方、1,2,3,4-ブタンテトラカルボン酸二無水物は、加水分解によって、1,2,3,4-ブタンテトラカルボン酸になり、架橋点として1分子あたり2つのカルボキシル基を持つ。したがって反応の当量は、キチンのN−アセチルグルコサミン残基1単位:BTCA=1:1である。以上より、実施例14におけるキチンN−アセチルグルコサミン残基1単位あたりに対するBTCAの反応当量倍数を求めると、3.1mmol/3.1 mmol= 1.0倍となる。   Chitin has two hydroxyl groups per N-acetylglucosamine residue as a crosslinking point. On the other hand, 1,2,3,4-butanetetracarboxylic dianhydride becomes 1,2,3,4-butanetetracarboxylic acid by hydrolysis and has two carboxyl groups per molecule as a crosslinking point. . Therefore, the equivalent amount of the reaction is 1 unit of N-acetylglucosamine residue of chitin: BTCA = 1: 1. From the above, the reaction equivalent multiple of BTCA per unit of chitin N-acetylglucosamine residue in Example 14 is 3.1 mmol / 3.1 mmol = 1.0.

〔実施例17〜21〕
BTCAの仕込量を変化させて、得られる生分解性高吸水性高分子について、最大吸水量に関するポリカルボン酸無水物の反応当量倍数依存性を調べた。原材料であるBTCAの配合量をそれぞれ、〔実施例17〕0.06g(0.31mmol)、〔実施例18〕0.30.g(1.55mmol)、〔実施例19〕1.5g (7.75 mmol)、〔実施例20〕3.0g (15.5 mmol)、〔実施例21〕6.0g(31.0mmol)に替えた以外は実施例1と同じ合成条件で、実施例17〜21の生分解性高吸水性高分子を得た。各実施例の反応当量倍数は、〔実施例17〕0.1倍、〔実施例18〕0.5倍、〔実施例19〕2.5倍、〔実施例20〕5.0倍、〔実施例21〕10.0倍である。
[Examples 17 to 21]
By varying the amount of BTCA charged, the biodegradable superabsorbent polymer obtained was examined for the reaction equivalent multiple dependence of the polycarboxylic acid anhydride on the maximum water absorption. [Example 17] 0.06 g (0.31 mmol), [Example 18] 0.30.g (1.55 mmol), [Example 19] 1.5 g (7.75 mmol), [Example 17] 20] Biodegradable superabsorbent polymers of Examples 17 to 21 were obtained under the same synthesis conditions as in Example 1 except that 3.0 g (15.5 mmol) and [Example 21] 6.0 g (31.0 mmol) were used. It was. The reaction equivalent multiples of each example are [Example 17] 0.1 times, [Example 18] 0.5 times, [Example 19] 2.5 times, [Example 20] 5.0 times, and [Example 21] 10.0 times. .

(合成物評価)
表7には、実施例16〜21の生分解性高吸水性高分子について反応当量倍数と架橋度を示し、また図9には吸水速度−吸水量チャートを示した。図9中の各実施例の吸水速度−吸水量曲線付近に示した数値は、各実施例のポリカルボン酸無水物の反応当量倍数を示す。なお、キチンそのものの吸水率は120時間経過後で5.4g/g-polymerである。この結果、ポリカルボン酸無水物の反応当量倍数が10倍〔実施例21〕のときに、48時間経過後吸水量が、乾燥時における自重の40倍の最大吸水量という最も高い値を示した。
(Composite evaluation)
Table 7 shows the reaction equivalent multiple and the degree of crosslinking for the biodegradable superabsorbent polymers of Examples 16 to 21, and FIG. 9 shows a water absorption rate-water absorption amount chart. The numerical values shown in the vicinity of the water absorption rate-water absorption amount curve of each example in FIG. 9 indicate the reaction equivalent multiple of the polycarboxylic acid anhydride of each example. The water absorption rate of chitin itself is 5.4 g / g-polymer after 120 hours. As a result, when the reaction equivalent multiple of the polycarboxylic acid anhydride was 10 times (Example 21), the water absorption after 48 hours showed the highest value of the maximum water absorption of 40 times its own weight during drying. .

〔実施例22〜25〕
反応溶媒をNMP100 mLにLiCl5gを溶解した溶媒から、DMSO 85 mLにTBAF 15gを溶解した溶媒に替えた以外は実施例16と同じ合成条件で、実施例22の生分解性高吸水性高分子を得た。また原材料であるBTCAの配合量をそれぞれ、〔実施例23〕1.5g (7.75 mmol)、〔実施例24〕3.0g (15.5 mmol) 、〔実施例25〕6.0g(31.0mmol)に替えた以外は実施例22と同じ合成条件で、実施例23〜25の生分解性高吸水性高分子を得た。各実施例の反応当量倍数は、〔実施例22〕1.0倍、〔実施例23〕2.5倍、〔実施例24〕5.0倍、〔実施例25〕10倍である。
[Examples 22 to 25]
The biodegradable superabsorbent polymer of Example 22 was prepared under the same synthesis conditions as Example 16 except that the reaction solvent was changed from a solvent in which 5 g of LiCl was dissolved in 100 mL of NMP to a solvent in which 15 g of TBAF was dissolved in 85 mL of DMSO. Obtained. Moreover, the compounding amount of BTCA which is a raw material was changed to [Example 23] 1.5 g (7.75 mmol), [Example 24] 3.0 g (15.5 mmol), and [Example 25] 6.0 g (31.0 mmol), respectively. Obtained the biodegradable superabsorbent polymers of Examples 23 to 25 under the same synthesis conditions as in Example 22. The reaction equivalent multiple of each Example is [Example 22] 1.0 times, [Example 23] 2.5 times, [Example 24] 5.0 times, and [Example 25] 10 times.

(合成物評価)
表8には、実施例22〜25の生分解性高吸水性高分子について反応当量倍数と架橋度を示し、また図10には吸水速度−吸水量チャートを示した。図9中の各実施例の吸水速度−吸水量曲線付近に示した数値は、各実施例のポリカルボン酸無水物の反応当量倍数を示す。この結果、ポリカルボン酸無水物の反応当量倍数が10倍〔実施例25〕のときに、48時間経過後吸水量が、乾燥時における自重の80倍の最大吸水量という最も高い値を示した。
(Composite evaluation)
Table 8 shows the reaction equivalent multiple and the degree of crosslinking of the biodegradable superabsorbent polymers of Examples 22 to 25, and FIG. 10 shows a water absorption rate-water absorption amount chart. The numerical values shown in the vicinity of the water absorption rate-water absorption amount curve of each example in FIG. 9 indicate the reaction equivalent multiple of the polycarboxylic acid anhydride of each example. As a result, when the reaction equivalent multiple of the polycarboxylic acid anhydride was 10 times [Example 25], the water absorption after 48 hours showed the highest value of the maximum water absorption of 80 times its own weight during drying. .

〔実施例26〜29〕
ポリカルボン酸無水物をBTCAからDSDA 1.11g(3.1mmol)に替えた以外は実施例16と同じ合成条件で、実施例26の生分解性高吸水性高分子を得た。またDSDAの配合量をそれぞれ、〔実施例27〕2.78g (7.75 mmol)、〔実施例28〕5.55g (15.5 mmol) 、〔実施例29〕11.1g(31.0mmol)に替えた以外は実施例26と同じ合成条件で、実施例27〜29の生分解性高吸水性高分子を得た。各実施例の反応当量倍数は、〔実施例26〕1.0倍、〔実施例27〕2.5倍、〔実施例28〕5.0倍、〔実施例29〕10倍である。
[Examples 26 to 29]
The biodegradable superabsorbent polymer of Example 26 was obtained under the same synthesis conditions as in Example 16 except that the polycarboxylic acid anhydride was changed from BTCA to 1.11 g (3.1 mmol) of DSDA. In addition, the amount of DSDA was changed to [Example 27] 2.78 g (7.75 mmol), [Example 28] 5.55 g (15.5 mmol), and [Example 29] 11.1 g (31.0 mmol), respectively. Biodegradable superabsorbent polymers of Examples 27 to 29 were obtained under the same synthesis conditions as in Example No. 26. The reaction equivalent multiple of each Example is [Example 26] 1.0 times, [Example 27] 2.5 times, [Example 28] 5.0 times, and [Example 29] 10 times.

(合成物評価)
表9には、実施例26〜29の生分解性高吸水性高分子について反応当量倍数と架橋度を示し、また図11には吸水速度−吸水量チャートを示した。図11中の各実施例の吸水速度−吸水量曲線付近に示した数値は、各実施例のポリカルボン酸無水物の反応当量倍数を示す。この結果、ポリカルボン酸無水物の反応当量倍数が10倍〔実施例29〕のときに、48時間経過後吸水量が、乾燥時における自重の230倍の最大吸水量という最も高い値を示した。
(Composite evaluation)
Table 9 shows the reaction equivalent multiple and the degree of crosslinking of the biodegradable superabsorbent polymers of Examples 26 to 29, and FIG. 11 shows a water absorption rate-water absorption amount chart. The numerical values shown in the vicinity of the water absorption rate-water absorption amount curve of each example in FIG. 11 indicate the reaction equivalent multiple of the polycarboxylic acid anhydride of each example. As a result, when the reaction equivalent multiple of the polycarboxylic acid anhydride was 10 times [Example 29], the water absorption after 48 hours showed the highest value of the maximum water absorption of 230 times its own weight during drying. .

(C.出発原料:キトサン)
下記実施例30〜34の合成条件の概要をまとめて表10に示した。
(C. Starting material: chitosan)
Table 10 summarizes the synthesis conditions of Examples 30 to 34 below.

〔実施例30〕
キトサン(和光純薬社製、キトサン50)0.50g(グルコサミン換算で3.1mmol)を10%(v/v)酢酸水溶液33.3mL中、室温下で溶解し、NMP、メタノールをそれぞれ33.3mL添加した。これにBTCA 6.0g(31mmol)を加え、室温で攪拌して、架橋反応を行わせた。なお、本合成条件では、溶媒の酢酸が触媒の役割も果たして架橋反応が進行するためDMAPなどの触媒を加える必要がない。架橋反応の後、24時間室温で放置した後200mLのアセトン中に注ぐことで架橋キトサンを析出させた。その後の操作は、実施例1に記載の手順で行い、実施例30の生分解性高吸水性高分子を得た。
Example 30
Chitosan (manufactured by Wako Pure Chemical Industries, Chitosan 50) 0.50 g (3.1 mmol in terms of glucosamine) was dissolved in 33.3 mL of 10% (v / v) acetic acid aqueous solution at room temperature, and 33.3 mL of NMP and methanol were added to each. To this, 6.0 g (31 mmol) of BTCA was added and stirred at room temperature to cause a crosslinking reaction. Under the present synthesis conditions, acetic acid as a solvent also serves as a catalyst and the crosslinking reaction proceeds, so there is no need to add a catalyst such as DMAP. After the crosslinking reaction, the mixture was allowed to stand at room temperature for 24 hours, and then poured into 200 mL of acetone to precipitate crosslinked chitosan. Subsequent operations were performed according to the procedure described in Example 1, and the biodegradable superabsorbent polymer of Example 30 was obtained.

キトサンは、架橋点としてグルコサミン残基あたり、2つの水酸基を持つ。一方、1,2,3,4-ブタンテトラカルボン酸二無水物は、加水分解によって、1,2,3,4-ブタンテトラカルボン酸になり、架橋点として1分子あたり2つのカルボキシル基を持つ。したがって反応の当量は、キトサンのグルコサミン残基1単位:BTCA=1:1である。以上より、実施例30におけるキトサンのグルコサミン残基1単位あたりに対するBTCAの反応当量倍数を求めると、31mmol/3.1 mmol= 10倍となる。   Chitosan has two hydroxyl groups per glucosamine residue as a crosslinking point. On the other hand, 1,2,3,4-butanetetracarboxylic dianhydride becomes 1,2,3,4-butanetetracarboxylic acid by hydrolysis and has two carboxyl groups per molecule as a crosslinking point. . Therefore, the equivalent amount of reaction is 1 unit of glucosamine residue of chitosan: BTCA = 1: 1. From the above, the reaction equivalent multiple of BTCA per unit of glucosamine residue of chitosan in Example 30 is 31 mmol / 3.1 mmol = 10 times.

〔実施例31〜34〕
BTCAの仕込量を変化させて、得られる生分解性高吸水性高分子について、最大吸水量に関するポリカルボン酸無水物の反応当量倍数依存性を調べた。原材料であるBTCAの配合量をそれぞれ、〔実施例31〕1.2g(6.2mmol)、〔実施例32〕3.0g(15.5mmol)、〔実施例33〕150g (775 mmol)、〔実施例34〕300g (1550 mmol) に替えた以外は実施例30と同じ合成条件で、実施例31〜34の生分解性高吸水性高分子を得た。各実施例の反応当量倍数は、〔実施例31〕2.0倍、〔実施例32〕5.0倍、〔実施例33〕25.0倍、〔実施例34〕50.0倍である。
[Examples 31-34]
By varying the amount of BTCA charged, the biodegradable superabsorbent polymer obtained was examined for the reaction equivalent multiple dependence of the polycarboxylic acid anhydride on the maximum water absorption. The blending amounts of BTCA as raw materials were [Example 31] 1.2 g (6.2 mmol), [Example 32] 3.0 g (15.5 mmol), [Example 33] 150 g (775 mmol), [Example 34]. The biodegradable superabsorbent polymers of Examples 31 to 34 were obtained under the same synthesis conditions as in Example 30 except that the amount was changed to 300 g (1550 mmol). The reaction equivalent multiple of each Example is [Example 31] 2.0 times, [Example 32] 5.0 times, [Example 33] 25.0 times, and [Example 34] 50.0 times.

(合成物評価)
表11には、実施例30〜34の生分解性高吸水性高分子について反応当量倍数と架橋度を示し、また図12には吸水速度−吸水量チャートを示した。図12中の各実施例の吸水速度−吸水量曲線付近に示した数値は、各実施例のポリカルボン酸無水物の反応当量倍数を示す。この結果、ポリカルボン酸無水物の反応当量倍数が50倍〔実施例34〕のときに、48時間経過後吸水量が、乾燥時における自重の450倍の最大吸水量という最も高い値を示した。
(Composite evaluation)
Table 11 shows the reaction equivalent multiple and the degree of crosslinking for the biodegradable superabsorbent polymers of Examples 30 to 34, and FIG. 12 shows a water absorption rate-water absorption amount chart. The numerical value shown near the water absorption rate-water absorption amount curve of each Example in FIG. 12 shows the reaction equivalent multiple of the polycarboxylic acid anhydride of each Example. As a result, when the reaction equivalent multiple of the polycarboxylic acid anhydride was 50 times (Example 34), the water absorption after 48 hours showed the highest value of the maximum water absorption of 450 times its own weight during drying. .

しかしながら、実施例31、実施例32、実施例30で得られた生分解性高吸水性高分子では、粒子径が細かく、JIS法の吸水試験(JIS K7223)で使用するティーバッグのナイロンメッシュシート(ポアサイズ225メッシュ)を抜けてしまうことがわかった。   However, the biodegradable superabsorbent polymer obtained in Example 31, Example 32, and Example 30 has a fine particle size, and is a nylon mesh sheet for tea bags used in the water absorption test of JIS method (JIS K7223). It was found that it would pass through (pore size 225 mesh).

(D.出発原料:アミロース)
〔実施例35〕
アミロース(林原社製アミロースEX-I)50g(グルコース換算で3.1mmol)を10%(v/v)酢酸水溶液33.3mL中、90℃で溶解し、その後室温まで冷却し、NMP、メタノールをそれぞれ33.3mL添加した。これにBTCA 9.2g(46.4 mmol)を加え、室温で攪拌して、架橋反応を行わせた。なお、本合成条件では、溶媒の酢酸が触媒の役割も果たして架橋反応が進行するためDMAPなどの触媒を加える必要がない。架橋反応の後、24時間室温で放置した後200mLのアセトン中に注ぐことで架橋キトサンを析出させた。その後の操作は、実施例1に記載の手順で行い、実施例35の生分解性高吸水性高分子を得た。
(D. Starting material: amylose)
Example 35
Amylose (Amylose EX-I manufactured by Hayashibara) 50 g (3.1 mmol in terms of glucose) was dissolved in 33.3 mL of 10% (v / v) acetic acid aqueous solution at 90 ° C., and then cooled to room temperature. mL was added. To this was added 9.2 g (46.4 mmol) of BTCA, and the mixture was stirred at room temperature to cause a crosslinking reaction. Under the present synthesis conditions, acetic acid as a solvent also serves as a catalyst and the crosslinking reaction proceeds, so there is no need to add a catalyst such as DMAP. After the crosslinking reaction, the mixture was allowed to stand at room temperature for 24 hours, and then poured into 200 mL of acetone to precipitate crosslinked chitosan. Subsequent operations were performed according to the procedure described in Example 1, and the biodegradable superabsorbent polymer of Example 35 was obtained.

アミロースは、架橋点としてグルコース残基あたり、3つの水酸基を持つ。一方、1,2,3,4-ブタンテトラカルボン酸二無水物は、加水分解によって、1,2,3,4-ブタンテトラカルボン酸になり、架橋点として1分子あたり2つのカルボキシル基を持つ。したがって反応の当量は、アミロースのグルコース残基1単位:BTCA=3:2である。以上より、実施例32におけるアミロースのグルコース残基1単位あたりに対するBTCAの反応当量倍数を求めると 2×46.4mmol/3×3.1 mmol=10倍となる。   Amylose has three hydroxyl groups per glucose residue as a crosslinking point. On the other hand, 1,2,3,4-butanetetracarboxylic dianhydride becomes 1,2,3,4-butanetetracarboxylic acid by hydrolysis and has two carboxyl groups per molecule as a crosslinking point. . Therefore, the equivalent of reaction is 1 unit of glucose residue of amylose: BTCA = 3: 2. From the above, the reaction equivalent multiple of BTCA per unit of glucose residue of amylose in Example 32 is 2 × 46.4 mmol / 3 × 3.1 mmol = 10 times.

(合成物評価)
実施例35の生分解性高吸水性高分子の架橋度は0.37であり、吸水時間ごとの吸水量は、乾燥時における自重に対して360倍(24時間後)、387倍(48時間後)であった。
(Composite evaluation)
The degree of cross-linking of the biodegradable superabsorbent polymer of Example 35 is 0.37, and the water absorption amount for each water absorption time is 360 times (after 24 hours) and 387 times (48 hours) with respect to its own weight during drying. After).

高吸水性高分子は、衛生用品、農業・園芸、流通資材、土木・建築、医療、トイレタリーまで幅広い用途で利用されており、本発明の生分解性高吸水性高分子の合成方法は、高い生分解性を付与しつつ、既存の高吸水性高分子に匹敵もしくは凌駕する吸水性能を持つ生分解性高吸水性高分子を合成できる、製造コストの抑えられた合成方法であるので、産業上の利用価値は高い。   Superabsorbent polymers are used in a wide range of applications, including sanitary products, agriculture / horticulture, distribution materials, civil engineering / architecture, medical care, toiletries, and the synthesis method of the biodegradable superabsorbent polymer of the present invention is high. Since it is a synthetic method that can synthesize biodegradable superabsorbent polymers with water absorption performance comparable to or surpassing that of existing superabsorbent polymers while providing biodegradability, it is a synthetic method with reduced manufacturing costs. The utility value of is high.

Claims (5)

セルロース、キチンもしくはこれらの混合物である天然由来高分子を、ポリカルボン酸無水物を用いて、塩化リチウムを含むN,N,-ジメチルアセトアミドの溶媒中でエステル架橋反応させる工程を含む生分解性高吸水性高分子の合成方法。 Highly biodegradable, including a step of subjecting a naturally-derived polymer that is cellulose, chitin, or a mixture thereof to an ester crosslinking reaction in a solvent of N, N, -dimethylacetamide containing lithium chloride using a polycarboxylic acid anhydride. A method for synthesizing a water-absorbing polymer. キトサン、多糖類もしくはこれらの混合物である天然由来高分子を、ポリカルボン酸無水物を用いて、メタノールとN-メチルピロリドンもしくはN,N,-ジメチルアセトアミドとメタノールとを含む酢酸水溶液中でエステル架橋反応させる工程を含む生分解性高吸水性高分子の合成方法。Ester cross-linking of naturally-occurring polymers such as chitosan, polysaccharides or mixtures of these in acetic acid aqueous solution containing methanol and N-methylpyrrolidone or N, N, -dimethylacetamide and methanol using polycarboxylic anhydride A method for synthesizing a biodegradable superabsorbent polymer comprising a step of reacting. 前記多糖類がアミロースである、請求項2記載の合成方法。The synthesis method according to claim 2, wherein the polysaccharide is amylose. 前記ポリカルボン酸無水物が1,2,3,4-ブタンテトラカルボン酸二無水物もしくは3,3',4,4'-ジフェニルスルホンテトラカルボン酸二無水物である、請求項1〜3いずれかの項記載の合成方法。The polycarboxylic acid anhydride is 1,2,3,4-butanetetracarboxylic dianhydride or 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride, any one of claims 1 to 3 A synthesis method according to any of the above sections. 請求項1〜4いずれかの項記載の合成方法で得られる生分解性高吸水性高分子。A biodegradable superabsorbent polymer obtained by the synthesis method according to claim 1.
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