JP6168892B2 - Water absorbent - Google Patents

Water absorbent Download PDF

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JP6168892B2
JP6168892B2 JP2013153082A JP2013153082A JP6168892B2 JP 6168892 B2 JP6168892 B2 JP 6168892B2 JP 2013153082 A JP2013153082 A JP 2013153082A JP 2013153082 A JP2013153082 A JP 2013153082A JP 6168892 B2 JP6168892 B2 JP 6168892B2
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naturally
water
biomass
derived polymer
hydrogel
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JP2015020157A (en
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山口　正史
正史 山口
宇山　浩
浩 宇山
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Uni Charm Corp
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Uni Charm Corp
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Priority to PCT/JP2014/069354 priority patent/WO2015012273A1/en
Priority to KR1020167002199A priority patent/KR102284629B1/en
Priority to CN201480013142.XA priority patent/CN105026033B/en
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    • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
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    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
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    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
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    • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
    • A61L15/42—Use of materials characterised by their function or physical properties
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    • B01J20/28004—Sorbent size or size distribution, e.g. particle size
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    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F2013/530131—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp
    • A61F2013/530226—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp with polymeric fibres
    • A61F2013/530313—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp with polymeric fibres being biodegradable
    • A61F2013/530321—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp with polymeric fibres being biodegradable in biopolymer, e.g. PHA
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    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F2013/530481—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials
    • A61F2013/530489—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials being randomly mixed in with other material
    • A61F2013/530496—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials being randomly mixed in with other material being fixed to fibres
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Description

本発明は、吸水剤に関する。より詳しくは、天然由来高分子から得られる生分解性の吸収剤に関する。   The present invention relates to a water absorbing agent. More specifically, the present invention relates to a biodegradable absorbent obtained from a naturally derived polymer.

使い捨ておむつや生理用品等の吸収性物品の吸収体には、一般に、高吸水性高分子（以下「ＳＡＰ」ともいう。）とフラッフパルプが使用されている。
ＳＡＰとして現在多用されているのは、ポリアクリル酸塩系などの合成ポリマー系ＳＡＰであるが、近年、ポリグルタミン酸塩系などの天然由来系ＳＡＰが生分解性の観点から注目されている。
たとえば、特許文献１は、γ−ポリグルタミン酸が少量のポリアミンで架橋された、高い膨潤度を有するゲルを提供すること、およびそのゲルを高い収率で得る方法を提供することを目的として、水溶性カルボジイミドおよびＮ−ヒドロキシコハク酸イミドを縮合剤および縮合補助剤として用いて、ポリアミン架橋γ−ポリグルタミン酸ゲルを製造する方法を開示している。
また、吸収性物品の薄物化、コンパクト化のために、フラッフパルプに対しＳＡＰの比率を上げようとする試みがある。しかし、ＳＡＰの比率が高くなるほど水の吸収の際に、ＳＡＰの特性に基づくいわゆる「ゲルブロッキング現象」が起り吸収体製品が計算通りの効率では機能しなくなるという問題がある。この問題を解決するために、特許文献２は、ＳＡＰの表面全体がセルロースあるいはセルロース誘導体から得られる水和性を有するミクロフィブリルにより被覆する方法を開示している。特許文献２に開示された方法によれば、ミクロフィブリルの分散媒体中にＳＡＰを分散すると、高濃度のＳＡＰを安定に分散することができ、分散媒体が除去される過程では、強固に自己接合してプラスター状になってネットワーク構造を形成し、ＳＡＰ粒子を包み込んで機械的に包囲すると同時に、ミクロフィブリル相互がイオン的な水素結合効果により結合し、ＳＡＰ粒子を確実に保持する（段落［００１７］参照）。 In general, superabsorbent polymers (hereinafter also referred to as “SAP”) and fluff pulp are used for absorbent bodies of absorbent articles such as disposable diapers and sanitary products.
Currently, synthetic polymer SAPs such as polyacrylates are widely used as SAPs. In recent years, naturally derived SAPs such as polyglutamates have attracted attention from the viewpoint of biodegradability.
For example, Patent Document 1 aims to provide a gel having a high degree of swelling, in which γ-polyglutamic acid is crosslinked with a small amount of polyamine, and to provide a method for obtaining the gel in high yield. Disclosed is a method for producing a polyamine-crosslinked γ-polyglutamic acid gel using a reactive carbodiimide and N-hydroxysuccinimide as a condensing agent and a condensing aid.
There are also attempts to increase the SAP ratio relative to fluff pulp in order to make absorbent articles thinner and more compact. However, as the SAP ratio increases, there is a problem that a so-called “gel blocking phenomenon” based on SAP characteristics occurs during water absorption, and the absorbent product does not function with the calculated efficiency. In order to solve this problem, Patent Document 2 discloses a method in which the entire surface of the SAP is coated with hydrated microfibrils obtained from cellulose or a cellulose derivative. According to the method disclosed in Patent Document 2, when SAP is dispersed in a microfibril dispersion medium, high-concentration SAP can be stably dispersed. In the process of removing the dispersion medium, strong self-bonding is achieved. As a result, it forms a plaster to form a network structure and encloses and mechanically surrounds the SAP particles, and at the same time, the microfibrils are bonded to each other by an ionic hydrogen bonding effect, and the SAP particles are securely held (paragraph [0017]. ]reference).

国際公開第２００７／０３４７８５号公報International Publication No. 2007/034785 特許第３０１６３６７号明細書Japanese Patent No. 3016367

特許文献１に開示された方法によれば、ポリアミン残基含有量が少なく、架橋密度が低く、膨潤度が高いゲルが提供される（段落［００３３］参照）。したがって、保水時の耐圧縮強度が低く、吸収性物品用途としては体圧下での液の滲み出しなど要求性能を満たすものにはなっていない。
特許文献２に開示された方法は、保水時のＳＡＰ同士の溶着によるゲルブロッキングに対しては効果があると思われるが、ゲルブロッキングを本質的に回避するためにはＳＡＰの耐圧縮強度（ゲル強度）自体を高める必要がある。ゲル強度を向上させるためには、架橋剤の添加量を増加させることによって架橋密度を高める方法が考えられるが、通常は架橋密度を高くすると吸水性能が低下する。また安全性や環境影響の観点からも架橋剤添加量を増加させることは望ましくない。 According to the method disclosed in Patent Document 1, a gel having a low polyamine residue content, a low crosslinking density, and a high degree of swelling is provided (see paragraph [0033]). Therefore, the compressive strength at the time of water retention is low, and it does not satisfy the required performance such as liquid oozing under body pressure as an absorbent article.
The method disclosed in Patent Document 2 seems to be effective for gel blocking due to welding of SAPs during water retention, but in order to essentially avoid gel blocking, the compressive strength of SAP (gel Strength) itself needs to be increased. In order to improve the gel strength, a method of increasing the crosslinking density by increasing the addition amount of the crosslinking agent is conceivable. Usually, when the crosslinking density is increased, the water absorption performance is lowered. Also, it is not desirable to increase the amount of crosslinking agent added from the viewpoint of safety and environmental impact.

本発明は、このような従来の問題点に着目してなされたものである。
本発明は、架橋した天然由来高分子およびバイオマスナノファイバーからなる吸水剤であって、架橋した天然由来高分子とバイオマスナノファイバーは粒子を形成し、バイオマスナノファイバーが粒子の内部に存在していることを特徴とする。
また、本発明の方法は、架橋した天然由来高分子およびバイオマスナノファイバーからなる吸水剤を製造する方法であって、
天然由来高分子を溶解し、天然由来高分子の溶液を調製する工程、
天然由来高分子の溶液にバイオマスナノファイバーを分散させ、バイオマスナノファイバーが分散した天然由来高分子の溶液を調製する工程、および
バイオマスナノファイバーが分散した天然由来高分子の溶液に架橋剤を添加し、天然由来高分子を架橋する工程
を含む。 The present invention has been made paying attention to such conventional problems.
The present invention is a water-absorbing agent comprising a crosslinked naturally-derived polymer and biomass nanofibers, wherein the crosslinked naturally-derived polymer and biomass nanofibers form particles, and the biomass nanofibers are present inside the particles. It is characterized by that.
The method of the present invention is a method for producing a water-absorbing agent comprising a cross-linked naturally-derived polymer and biomass nanofiber,
Dissolving a naturally-derived polymer and preparing a solution of the naturally-derived polymer;
A process of preparing biomass-derived nanofibers in which biomass nanofibers are dispersed by adding biomass nanofibers to a naturally-occurring polymer solution, and adding a cross-linking agent to the naturally-derived polymer solution in which biomass nanofibers are dispersed. And a step of crosslinking the naturally-derived polymer.

本発明は、次の態様を含む。
［１］架橋した天然由来高分子およびバイオマスナノファイバーからなる吸水剤であって、架橋した天然由来高分子とバイオマスナノファイバーは粒子を形成し、バイオマスナノファイバーが粒子の内部に存在していることを特徴とする吸水剤。
［２］天然由来高分子が縮合性の官能基を有することを特徴とする［１］に記載の吸水剤。
［３］天然由来高分子がポリグルタミン酸であることを特徴とする［１］または［２］に記載の吸水剤。
［４］バイオマスナノファイバーの平均直径が４〜１０００ｎｍであることを特徴とする［１］〜［３］のいずれか１つに記載の吸水剤。
［５］架橋した天然由来高分子およびバイオマスナノファイバーからなる吸水剤を製造する方法であって、
天然由来高分子を溶解し、天然由来高分子の溶液を調製する工程、
天然由来高分子の溶液にバイオマスナノファイバーを分散させ、バイオマスナノファイバーが分散した天然由来高分子の溶液を調製する工程、および
バイオマスナノファイバーが分散した天然由来高分子の溶液に架橋剤を添加し、天然由来高分子を架橋する工程
を含む方法。
［６］天然由来高分子を架橋する工程において得られた架橋した天然由来高分子を含むヒドロゲルを湿式粉砕する工程をさらに含む［５］に記載の方法。
［７］湿式粉砕したヒドロゲルに水混和性有機溶媒を加え、ヒドロゲルを脱水する工程をさらに含む［６］に記載の方法。
［８］脱水したヒドロゲルを乾燥する工程をさらに含む［７］に記載の方法。
［９］バイオマスナノファイバーの量が天然由来高分子とバイオマスナノファイバーの合計量１００質量部（固形分基準）に対し１〜３０質量部（固形分基準）であることを特徴とする［５］〜［８］のいずれか１つに記載の方法。
［１０］［１］〜［４］のいずれか１つに記載の吸水剤を含む吸収性物品。 The present invention includes the following aspects.
[1] A water-absorbing agent comprising a cross-linked naturally-derived polymer and biomass nanofibers, wherein the cross-linked naturally-derived polymer and biomass nanofibers form particles, and the biomass nanofibers are present inside the particles. Water-absorbing agent characterized by
[2] The water-absorbing agent according to [1], wherein the naturally-derived polymer has a condensable functional group.
[3] The water-absorbing agent according to [1] or [2], wherein the naturally derived polymer is polyglutamic acid.
[4] The water-absorbing agent according to any one of [1] to [3], wherein an average diameter of the biomass nanofiber is 4 to 1000 nm.
[5] A method for producing a water-absorbing agent comprising a cross-linked naturally-derived polymer and biomass nanofiber,
Dissolving a naturally-derived polymer and preparing a solution of the naturally-derived polymer;
A process of preparing biomass-derived nanofibers in which biomass nanofibers are dispersed by adding biomass nanofibers to a naturally-occurring polymer solution, and adding a cross-linking agent to the naturally-derived polymer solution in which biomass nanofibers are dispersed. A method comprising a step of crosslinking a naturally-derived polymer.
[6] The method according to [5], further including a step of wet-grinding the hydrogel containing the crosslinked naturally-derived polymer obtained in the step of crosslinking the naturally-derived polymer.
[7] The method according to [6], further comprising a step of adding a water-miscible organic solvent to the wet-pulverized hydrogel to dehydrate the hydrogel.
[8] The method according to [7], further comprising a step of drying the dehydrated hydrogel.
[9] The amount of the biomass nanofiber is 1 to 30 parts by mass (solid content basis) with respect to 100 parts by mass (solid content basis) of the total amount of the naturally derived polymer and the biomass nanofiber [5] -The method as described in any one of [8].
[10] An absorbent article comprising the water-absorbing agent according to any one of [1] to [4].

本発明によれば、粒子内部にまでバイオマスナノファイバーを複合した天然由来の高吸水性高分子としたことにより、保水性能が高く、かつ吸水時のゲル強度も大きい吸水剤を得ることができる。
また、バイオマスナノファイバーの主原料は天然由来であり、化学架橋剤の添加量も低水準に抑えることができることから、一般的なポリアクリル酸塩系のＳＡＰに比べＣＯ２排出量を低くすることが可能であり、かつ水洗廃棄・土中廃棄した場合も、速やかに生分解し環境適応性が高い。さらには一般的なポリアクリル酸塩系のＳＡＰに比べ生体適合性も高い。 According to the present invention, a water-absorbing agent having high water retention performance and high gel strength at the time of water absorption can be obtained by using a naturally-derived highly water-absorbing polymer in which biomass nanofibers are combined even inside the particles.
In addition, the main raw material for biomass nanofibers is naturally derived, and the amount of chemical cross-linking agent added can be kept at a low level. Therefore, CO 2 emissions must be reduced compared to general polyacrylate-based SAPs. In addition, even when washed with water or disposed in the soil, it is quickly biodegradable and highly adaptable to the environment. Furthermore, the biocompatibility is high as compared with a general polyacrylate SAP.

図１は、本発明の吸水剤の粒子の外観の電子顕微鏡写真（倍率１００倍）である。FIG. 1 is an electron micrograph (magnification 100 times) of the appearance of particles of the water-absorbing agent of the present invention. 図２は、本発明の吸水剤の粒子を一旦イオン交換水で膨潤させたものを凍結乾燥し、その外表面を撮影した電子顕微鏡写真（倍率５００倍）である。FIG. 2 is an electron micrograph (magnification 500 times) obtained by freeze-drying the water-absorbing agent particles of the present invention once swelled with ion-exchanged water and photographing the outer surface thereof. 図３は、本発明の吸水剤の粒子を一旦イオン交換水で膨潤させたものを凍結乾燥し、その外表面を撮影した電子顕微鏡写真（倍率３０００倍）である。FIG. 3 is an electron micrograph (magnification 3000 times) of the outer surface of the water-absorbing agent particles of the present invention once swelled with ion-exchanged water and freeze-dried. 図４は、本発明の吸水剤の粒子を一旦イオン交換水で膨潤させたものを凍結乾燥し、その断面を撮影した電子顕微鏡写真（倍率５００倍）である。FIG. 4 is an electron micrograph (magnification 500 times) obtained by freeze-drying the water-absorbing agent particles of the present invention once swelled with ion-exchanged water and photographing a cross section thereof. 図５は、本発明の吸水剤の粒子を一旦イオン交換水で膨潤させたものを凍結乾燥し、その断面を撮影した電子顕微鏡写真（倍率３０００倍）である。FIG. 5 is an electron micrograph (magnification 3000 times) of a cross-section of the water-absorbing agent particles of the present invention once swelled with ion-exchanged water and freeze-dried. 図６は、本発明の吸水剤の原料であるバイオマスナノファイバーの電子顕微鏡写真である。FIG. 6 is an electron micrograph of biomass nanofibers that are raw materials for the water-absorbing agent of the present invention.

本発明は、架橋した天然由来高分子およびバイオマスナノファイバーからなる吸水剤であって、架橋した天然由来高分子とバイオマスナノファイバーは粒子を形成し、バイオマスナノファイバーが粒子の内部に存在していることを特徴とする。   The present invention is a water-absorbing agent comprising a crosslinked naturally-derived polymer and biomass nanofibers, wherein the crosslinked naturally-derived polymer and biomass nanofibers form particles, and the biomass nanofibers are present inside the particles. It is characterized by that.

本発明に使用する天然由来高分子は、天然由来の高分子であれば、特に限定するものではない。天然由来高分子は、微生物による発酵で得られる高分子、天然物から抽出される高分子などをいい、一般にバイオポリマーとも呼ばれる。
天然由来高分子は、縮合性の官能基を有することが好ましく、親水性であることが好ましい。縮合性の官能基は、架橋剤と反応して、天然由来高分子を架橋するために寄与する。縮合性の官能基の例としては、カルボキシル基、アミノ基などが挙げられるが、なかでもカルボキシル基が、親水性をも付与するので、好ましい。
天然由来高分子の具体例としては、ポリグルタミン酸（以下「ＰＧＡ」ともいう。）、ポリアスパラギン酸、ポリリジン、ポリアルギニンなどのポリアミノ酸、アルギン酸、ヒアルロン酸、キトサンなどの多糖類、カルボキシメチルセルロースなど天然高分子に化学修飾が施されたものが挙げられるが、これらに限定されない。ポリアミノ酸は共重合体でもよい。また、天然由来高分子は２種以上を混合して用いてもよい。
天然由来高分子の分子量は、特に限定されないが、質量平均分子量が好ましくは１万〜１３００万であり、より好ましくは５万〜１０００万であり、さらに好ましくは３０万〜５００万である。分子量が小さすぎると重量あたりでの未架橋の分子鎖が増え、溶出分が多く強度が低いゲルになる。分子量が大きすぎると溶解時の粘度が大きくなり、バイオマスナノファイバーや架橋剤が均一に分散されない。
架橋した天然由来高分子とは、天然由来高分子を架橋剤と反応させて、架橋したものをいう。架橋については後述する。 The naturally-derived polymer used in the present invention is not particularly limited as long as it is a naturally-derived polymer. Naturally-derived polymers refer to polymers obtained by fermentation with microorganisms, polymers extracted from natural products, and the like, and are generally called biopolymers.
The naturally derived polymer preferably has a condensable functional group, and is preferably hydrophilic. The condensable functional group contributes to reacting with the crosslinking agent to crosslink the naturally derived polymer. Examples of the condensable functional group include a carboxyl group and an amino group, and among them, the carboxyl group is preferable because it also imparts hydrophilicity.
Specific examples of naturally derived polymers include polyglutamic acid (hereinafter also referred to as “PGA”), polyamino acids such as polyaspartic acid, polylysine, and polyarginine, polysaccharides such as alginic acid, hyaluronic acid, and chitosan, and natural substances such as carboxymethylcellulose. Examples include, but are not limited to, polymers obtained by chemically modifying polymers. The polyamino acid may be a copolymer. Naturally derived polymers may be used as a mixture of two or more.
The molecular weight of the naturally derived polymer is not particularly limited, but the mass average molecular weight is preferably 10,000 to 13 million, more preferably 50,000 to 10 million, and still more preferably 300,000 to 5,000,000. If the molecular weight is too small, the number of uncrosslinked molecular chains per weight increases, resulting in a gel with a large amount of elution and low strength. If the molecular weight is too large, the viscosity at the time of dissolution increases, and the biomass nanofibers and the crosslinking agent are not uniformly dispersed.
The cross-linked naturally-derived polymer refers to a polymer obtained by reacting a naturally-derived polymer with a crosslinking agent. The crosslinking will be described later.

本発明において、バイオマスナノファイバーとは、平均直径が４〜１０００ｎｍであるバイオマスファイバーをいう。バイオマスナノファイバーの平均直径は、好ましくは５〜５００ｎｍであり、より好ましくは１０〜１００ｎｍである。平均直径が小さすぎるとバイオマスナノファイバー自体の機械的強度が低くなり、補強効果が望めない。平均直径が大きすぎるとバイオマスナノファイバー同士が交絡しにくくなる。バイオマスナノファイバーの長さは、特に限定されないが、通常、直径の１００倍以上である。平均直径および長さは電子線顕微鏡によって測定することができる。   In the present invention, the biomass nanofiber refers to a biomass fiber having an average diameter of 4 to 1000 nm. The average diameter of the biomass nanofiber is preferably 5 to 500 nm, more preferably 10 to 100 nm. If the average diameter is too small, the mechanical strength of the biomass nanofiber itself is lowered, and a reinforcing effect cannot be expected. If the average diameter is too large, the biomass nanofibers are difficult to interlace. Although the length of biomass nanofiber is not specifically limited, Usually, it is 100 times or more of a diameter. The average diameter and length can be measured with an electron beam microscope.

バイオマスナノファイバーの製造方法は特に限定されず、いかなる方法により製造してもよい。たとえば、バイオマスの分散流体を高圧噴射して衝突用硬質体に衝突させて、バイオマスを湿式粉砕することによって、バイオマスナノファイバーを製造することができる。高圧噴射の圧力は好ましくは１００〜２４５ＭＰａであり、噴射速度は好ましくは４４０〜７００ｍ／ｓである。高圧噴射して衝突用硬質体に衝突させたバイオマスの分散流体は回収し、再度ノズルより衝突用硬質体に向けて高圧噴射され、この操作を必要な回数、例えば１〜５０回程度、好ましくは１〜４０回程度、より好ましくは１〜３０回程度、さらに好ましくは１〜２０回程度、特に好ましくは１〜１０回程度繰り返す。バイオマスは、衝突用硬質体に衝突することで、繊維の絡まりがほどけ、繊維径が縮小し、ナノサイズに微細化していく。なお、衝突用硬質体としては、ボール状、平板状などの形状が挙げられる。分散流体を高圧噴射するノズルの直径は、好ましくは０．１〜０．８ｍｍである。
その他、二軸混練機で混練処理して強固な二次壁を解繊する方法、パルプスラリーを狭い空隙に押し込み圧力の解放で解繊を進める高圧ホモジナイザーやマイクロフリュイダイザーといった方法、回転する砥石間でパルプを磨砕するグラインダー法、セルロース表面にカルボキシル基を選択的に導入するＴＥＭＰＯ酸化によりセルロースナノファイバー間の相互作用を大きく低下させ、パルプスラリーをブレンダーで撹拌するだけの方法などにより、セルロースナノファイバーを製造することもできる。
バイオマスナノファイバーの主原料となるバイオマスとしては、セルロース、キチン、キトサンなどが挙げられる。セルロースとしては、針葉樹さらしクラフトパルプ（ＮＢＫＰ）、広葉樹系パルプ、コットンリンター等の綿系パルプ、麦わらパルプ、バガスパルプなどの非木材系パルプ、バクテリアセルロースなどが挙げられるが、平均分子量やコストの観点からＮＢＫＰが好ましい。
また、バイオマスナノファイバーは、株式会社スギノマシンから「ＢｉＮＦｉ−ｓ」という商品名で市販されている。そのような市販品もまた、本発明において使用することができる。 The manufacturing method of biomass nanofiber is not particularly limited, and may be manufactured by any method. For example, biomass nanofibers can be produced by high-pressure jetting a biomass dispersion fluid and causing it to collide with a collision hard body to wet-grind the biomass. The pressure of the high pressure injection is preferably 100 to 245 MPa, and the injection speed is preferably 440 to 700 m / s. The dispersed fluid of biomass that has been injected with high pressure and collided with the collision hard body is collected and again injected with high pressure from the nozzle toward the collision hard body, and this operation is performed a required number of times, for example, about 1 to 50 times, preferably Repeat about 1 to 40 times, more preferably about 1 to 30 times, still more preferably about 1 to 20 times, and particularly preferably about 1 to 10 times. When the biomass collides with the collision hard body, the fibers are untangled, the fiber diameter is reduced, and the nano size is reduced. In addition, as a hard body for collision, shapes, such as ball shape and flat plate shape, are mentioned. The diameter of the nozzle that jets the dispersion fluid at high pressure is preferably 0.1 to 0.8 mm.
In addition, a method of kneading with a twin-screw kneader to defibrate a strong secondary wall, a method such as a high-pressure homogenizer or microfluidizer that pushes pulp slurry into a narrow gap and advances defibration by releasing pressure, between rotating grinding wheels Cellulose nanofibers can be produced by a grinder method that grinds pulp with cellulose, a method in which the interaction between cellulose nanofibers is greatly reduced by TEMPO oxidation that selectively introduces carboxyl groups on the cellulose surface, and the pulp slurry is simply stirred with a blender. Fiber can also be produced.
Examples of biomass that is a main raw material for biomass nanofibers include cellulose, chitin, and chitosan. Examples of cellulose include softwood bleached kraft pulp (NBKP), hardwood pulp, cotton pulp such as cotton linter, non-wood pulp such as straw pulp, bagasse pulp, and bacterial cellulose, but from the viewpoint of average molecular weight and cost. NBKP is preferred.
Biomass nanofibers are commercially available from Sugino Machine Co., Ltd. under the trade name “BiNFi-s”. Such commercial products can also be used in the present invention.

本発明の吸水剤を構成する架橋した天然由来高分子とバイオマスナノファイバーは粒子を形成している。粒子の形状は、特に限定されないが、好ましくは球状である。粒子の大きさ（投影面積円相当径）は、好ましくは１５０〜８５０μｍであり、より好ましくは２００〜６００μｍであり、さらに好ましくは３００〜４００μｍである。粒子が小さすぎると膨潤時の粒子間隙が小さくなり、吸収体に組み込んだ際にはブロッキングを引き起こしてしまう。粒子が大きすぎると比表面積が小さくなり吸水速度が遅くなってしまう。粒子の大きさ（投影面積円相当径）は電子線顕微鏡によって測定することができる。   The crosslinked naturally-derived polymer and the biomass nanofiber constituting the water-absorbing agent of the present invention form particles. The shape of the particles is not particularly limited, but is preferably spherical. The size of the particles (equivalent diameter of projected area circle) is preferably 150 to 850 μm, more preferably 200 to 600 μm, and further preferably 300 to 400 μm. If the particles are too small, the particle gap at the time of swelling becomes small, and when incorporated in an absorber, blocking is caused. If the particles are too large, the specific surface area becomes small and the water absorption speed becomes slow. The size of the particles (projected area equivalent circle diameter) can be measured with an electron microscope.

本発明の吸水剤においては、バイオマスナノファイバーが粒子の内部に存在している。ただし、バイオマスナノファイバーの全体が粒子の内部に存在している必要はなく、バイオマスナノファイバーの一部は粒子の外部（表面から外）に露出していてもよい。本発明の吸水剤の粒子の外観の電子顕微鏡写真（倍率１００倍）を図１に示す。また、粒子を一旦イオン交換水で膨潤させたものを凍結乾燥し、その外表面を撮影した電子顕微鏡写真を、図２（倍率５００倍）および図３（倍率３０００倍）に示す。また、粒子を一旦イオン交換水で膨潤させたものを凍結乾燥し、その断面を撮影した電子顕微鏡写真を、図４（倍率５００倍）および図５（倍率３０００倍）に示す。図６は、本発明の吸水剤の原料であるバイオマスナノファイバーの電子顕微鏡写真である。   In the water-absorbing agent of the present invention, biomass nanofibers are present inside the particles. However, it is not necessary for the entire biomass nanofibers to be present inside the particles, and part of the biomass nanofibers may be exposed to the outside of the particles (outside from the surface). FIG. 1 shows an electron micrograph (magnification 100 times) of the appearance of the water-absorbing agent particles of the present invention. Also, electron micrographs obtained by freeze-drying particles once swollen with ion-exchanged water and photographing the outer surface are shown in FIG. 2 (magnification 500 times) and FIG. 3 (magnification 3000 times). In addition, the electron micrographs obtained by freeze-drying the particles once swollen with ion-exchanged water and photographing the cross section are shown in FIG. 4 (magnification 500 times) and FIG. 5 (magnification 3000 times). FIG. 6 is an electron micrograph of biomass nanofibers that are raw materials for the water-absorbing agent of the present invention.

本発明は、バイオマスナノファイバーを添加してゲル強度を上げている。ゲル強度を上げるために、架橋剤の添加量を増やす方法が考えられるが、その場合は、架橋密度が高まることにより、吸水時でもゲル強度が大きくなる。化学的な結合により架橋するため架橋点は強固であり、その密度を上げることで膨潤変形を阻害する要因になる。一方、本発明のように、バイオマスナノファイバーを添加してゲル強度を上げる場合は、交絡したバイオマスナノファイバーの機械的強度によってゲル強度が大きくなる。化学的結合のように強固なつながりではないので、膨潤変形に対して比較的自由度が出る。なお、バイオマスナノファイバーが長くなるほど交絡しやすくなる。微細繊維化していないバイオマスでは、交絡されにくい。バイオマスナノファイバーを添加しても、ＰＧＡがまったく化学架橋されていない状態であれば、ＰＧＡは溶解してしまう。   In the present invention, biomass nanofibers are added to increase the gel strength. In order to increase the gel strength, a method of increasing the amount of the crosslinking agent added is conceivable. In this case, the gel strength increases even during water absorption due to an increase in the crosslinking density. The cross-linking points are strong because they are cross-linked by chemical bonds, and the density is increased to inhibit swelling deformation. On the other hand, when increasing the gel strength by adding biomass nanofibers as in the present invention, the gel strength is increased by the mechanical strength of the entangled biomass nanofibers. Since it is not as strong as chemical bonds, it has a relatively high degree of freedom for swelling deformation. In addition, it becomes easy to entangle as biomass nanofiber becomes long. Biomass that has not been made into fine fibers is less likely to be entangled. Even if biomass nanofibers are added, if PGA is not chemically crosslinked at all, PGA will be dissolved.

架橋した天然由来高分子とバイオマスナノファイバーの比率は、架橋した天然由来高分子とバイオマスナノファイバーの合計量１００質量部（固形分基準）に対し、バイオマスナノファイバーが好ましくは０．１〜４０質量部（固形分基準）であり、より好ましくは３〜３０質量部（固形分基準）であり、さらに好ましくは５〜２０質量部（固形分基準）である。バイオマスナノファイバーの量が少なすぎると十分な機械的強度が得られない。バイオマスナノファイバーの量が多すぎると架橋効率が低下することで弱いゲルになる。   The ratio of the cross-linked naturally-derived polymer and biomass nanofiber is preferably 0.1 to 40 mass for biomass nanofiber with respect to 100 mass parts (solid content basis) of the total amount of cross-linked naturally-derived polymer and biomass nanofiber. Parts (solid content basis), more preferably 3 to 30 parts by mass (solid content basis), and further preferably 5 to 20 parts by mass (solid content basis). If the amount of biomass nanofiber is too small, sufficient mechanical strength cannot be obtained. When there is too much quantity of biomass nanofiber, it will become a weak gel because crosslinking efficiency falls.

次に、本発明の吸水剤の製造方法を説明する。
本発明の吸水剤の製造方法は、天然由来高分子を溶解し、天然由来高分子の溶液を調製する工程（溶解工程）、天然由来高分子の溶液にバイオマスナノファイバーを分散させ、バイオマスナノファイバーが分散した天然由来高分子の溶液を調製する工程（分散工程）、およびバイオマスナノファイバーが分散した天然由来高分子の溶液に架橋剤を添加し、天然由来高分子を架橋する工程（架橋工程）を含む。
本発明の製造方法は、さらに、天然由来高分子を架橋する工程において得られた架橋した天然由来高分子を含むヒドロゲルを湿式粉砕する工程（粉砕工程）、湿式粉砕したヒドロゲルに水混和性有機溶媒を加え、ヒドロゲルを脱水する工程（脱水工程）、脱水したヒドロゲルを乾燥する工程（乾燥工程）の１つ以上の工程を含んでもよい。 Next, the manufacturing method of the water absorbing agent of this invention is demonstrated.
The method for producing a water-absorbing agent of the present invention includes a step of dissolving a naturally-derived polymer and preparing a solution of the naturally-derived polymer (dissolution step), dispersing the biomass nanofiber in the solution of the naturally-derived polymer, A step of preparing a solution of a naturally-derived polymer with dispersed therein (dispersion step), and a step of adding a crosslinking agent to the solution of the naturally-derived polymer in which biomass nanofibers are dispersed to crosslink the naturally-derived polymer (crosslinking step). including.
The production method of the present invention further includes a step of wet-grinding a hydrogel containing a cross-linked naturally-derived polymer obtained in the step of cross-linking a naturally-derived polymer (grinding step), a water-miscible organic solvent in the wet-ground hydrogel And may include one or more steps of dehydrating the hydrogel (dehydration step) and drying the dehydrated hydrogel (drying step).

天然由来高分子の溶液を調製する工程（溶解工程）は、前述の天然由来高分子を水などの溶媒に溶解させることにより行うことができる。溶媒としては、水が好ましい。溶媒として水を用いたときは、天然由来高分子の水溶液が得られる。溶液中の天然由来高分子の濃度は、好ましくは１〜３０質量％（固形分基準）であり、より好ましくは３〜２０質量％（固形分基準）であり、さらに好ましくは５〜１０質量％（固形分基準）である。天然由来高分子の濃度が薄すぎると複合品の回収量が低く生産性が悪くなる。天然由来高分子の濃度が濃すぎると粘度が高くなり、バイオマスナノファイバーや架橋剤の分散性が悪くなる。溶解させる方法は、特に限定されず、溶媒に天然由来高分子を加え、撹拌することによって、溶解させることができる。
なお、架橋した天然由来高分子は水溶液中で架橋反応させることによって得られるため、天然由来高分子は水溶性の塩の形態であることが好ましい。たとえば、カルボキシル基を有する天然由来高分子は、ナトリウム塩、カリウム塩などの金属塩、またはアンモニウム塩、アミン塩などの形態であることが好ましく、アミノ基を有する天然由来高分子は、塩酸塩、硫酸塩などの無機酸塩、または酢酸塩などの有機酸塩の形態であることが好ましい。 The step of preparing the naturally derived polymer solution (dissolution step) can be performed by dissolving the aforementioned naturally derived polymer in a solvent such as water. As the solvent, water is preferable. When water is used as a solvent, an aqueous solution of a naturally derived polymer is obtained. The concentration of the naturally derived polymer in the solution is preferably 1 to 30% by mass (based on solid content), more preferably 3 to 20% by mass (based on solid content), and further preferably 5 to 10% by mass. (Based on solid content). If the concentration of the naturally derived polymer is too thin, the recovered amount of the composite product is low and the productivity is deteriorated. If the concentration of the naturally-derived polymer is too high, the viscosity becomes high, and the dispersibility of the biomass nanofiber and the crosslinking agent becomes poor. The method of dissolving is not particularly limited, and it can be dissolved by adding a naturally derived polymer to a solvent and stirring.
In addition, since the naturally-derived polymer crosslinked is obtained by a crosslinking reaction in an aqueous solution, the naturally-derived polymer is preferably in the form of a water-soluble salt. For example, the naturally-derived polymer having a carboxyl group is preferably in the form of a metal salt such as sodium salt or potassium salt, or an ammonium salt or an amine salt, and the naturally-derived polymer having an amino group is hydrochloride, It is preferably in the form of an inorganic acid salt such as sulfate or an organic acid salt such as acetate.

次に、天然由来高分子の溶液にバイオマスナノファイバーを分散させ、バイオマスナノファイバーが分散した天然由来高分子の溶液を調製する（分散工程）。
バイオマスナノファイバーを天然由来高分子の溶液に分散させる方法は、特に限定されないが、たとえば、バイオマスナノファイバーを天然由来高分子の溶液に加えて撹拌混合する方法、あらかじめバイオマスナノファイバーの分散液を調製し、そのバイオマスナノファイバーの分散液を天然由来高分子の溶液に加えて混合する方法、バイオマスナノファイバーの原料であるバイオマスを天然由来高分子の溶液に加え、天然由来高分子の溶液中でバイオマスを湿式粉砕してナノファイバー化する方法が挙げられるが、あらかじめバイオマスナノファイバーの分散液を調製し、そのバイオマスナノファイバーの分散液を天然由来高分子の溶液に加えて混合する方法が好ましい。バイオマスナノファイバーの分散液を調製する方法としては、前述したバイオマスナノファイバーの製造方法を採用することができ、たとえば、バイオマスを水に分散させたバイオマスの分散液を１００〜２４５ＭＰａで高圧噴射して衝突用硬質体に衝突させて、バイオマスを湿式粉砕することによって、バイオマスナノファイバーの分散液を調製することができる。 Next, the biomass nanofibers are dispersed in the natural polymer solution to prepare a natural polymer solution in which the biomass nanofibers are dispersed (dispersing step).
The method for dispersing the biomass nanofibers in the natural polymer solution is not particularly limited. For example, the biomass nanofibers are added to the natural polymer solution and stirred and mixed, and the biomass nanofiber dispersion is prepared in advance. The biomass nanofiber dispersion is added to the naturally occurring polymer solution and mixed, and the biomass that is the raw material of the biomass nanofiber is added to the naturally occurring polymer solution, and the biomass in the naturally occurring polymer solution is added. There is a method of wet-grinding to form nanofibers, but it is preferable to prepare a biomass nanofiber dispersion in advance and add the biomass nanofiber dispersion to the naturally occurring polymer solution and mix. As a method for preparing a dispersion of biomass nanofibers, the above-described method for producing biomass nanofibers can be employed. For example, a biomass dispersion in which biomass is dispersed in water is injected at a high pressure of 100 to 245 MPa. A biomass nanofiber dispersion can be prepared by colliding with the impacting hard body and wet pulverizing the biomass.

次に、バイオマスナノファイバーが分散した天然由来高分子の溶液に架橋剤を添加し、天然由来高分子を架橋する（架橋工程）。架橋剤としては、天然由来高分子を架橋することができるものであれば、特に限定されない。
たとえば、天然由来高分子がカルボキシル基を有する場合は、１，２−エチレンジアミン、１，３−プロパンジアミン、１，４−ブタンジアミン、１，５−ヘプタンジアミン、１，６−ヘキサンジアミンなどのアルキレンジアミン、ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ペンタエチレンヘキサミン、ポリエチレンイミンなどのアミノ基を２個以上有する化合物（以下「ポリアミン」ともいう。）、ポリリジン、キトサンなどのアミノ基含有ポリマーなどを架橋剤として使用することができる。 Next, a crosslinking agent is added to the solution of the naturally derived polymer in which the biomass nanofibers are dispersed to crosslink the naturally derived polymer (crosslinking step). The crosslinking agent is not particularly limited as long as it can crosslink naturally derived polymers.
For example, when the naturally-derived polymer has a carboxyl group, alkylene such as 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-heptanediamine, 1,6-hexanediamine, etc. Compounds having two or more amino groups such as diamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine (hereinafter also referred to as “polyamine”), amino group-containing polymers such as polylysine and chitosan, etc. It can be used as a crosslinking agent.

天然由来高分子がアミノ基を有する場合は、天然由来高分子を架橋させるために用いられる架橋剤としては、フマル酸、マレイン酸、イタコン酸、シトラコン酸、トリメリット酸などのカルボキシル基を２個以上有する化合物、ポリアクリル酸、ポリメタクリル酸、ポリ−γ−グルタミン酸、アルギン酸、ヒアルロン酸などのカルボキシル基含有ポリマーなどを架橋剤として使用することができる。   When the naturally-derived polymer has an amino group, the crosslinking agent used for crosslinking the naturally-derived polymer includes two carboxyl groups such as fumaric acid, maleic acid, itaconic acid, citraconic acid, and trimellitic acid. The compounds having the above, a carboxyl group-containing polymer such as polyacrylic acid, polymethacrylic acid, poly-γ-glutamic acid, alginic acid, and hyaluronic acid can be used as a crosslinking agent.

天然由来高分子を架橋させる際の架橋剤の使用量は、天然由来高分子１００モルに対し、好ましくは０．０１〜１００モルであり、より好ましくは０．１〜２０モルであり、さらに好ましくは０．３〜１０モルである。架橋剤の量が少なすぎると、架橋密度が低くなりやすく、ゲルの状態が得られにくくなるおそれがある。架橋剤の量が多すぎると、架橋密度が高くなりやすく、得られる吸収剤の膨潤度が低くなるおそれがある。   The amount of the crosslinking agent used for crosslinking the naturally-derived polymer is preferably 0.01 to 100 mol, more preferably 0.1 to 20 mol, and still more preferably, with respect to 100 mol of the naturally-derived polymer. Is 0.3 to 10 mol. If the amount of the crosslinking agent is too small, the crosslinking density tends to be low, and the gel state may be difficult to obtain. When there is too much quantity of a crosslinking agent, there exists a possibility that a crosslinking density may become high easily and the swelling degree of the absorber obtained may become low.

架橋剤とともに、縮合剤や縮合助剤を併用してもよい。縮合剤や縮合助剤を併用すると、より効率よくアミド結合を形成させることができる。
縮合剤としては、水溶性カルボジイミドが挙げられる。水溶性カルボジイミドとは、分子内にカルボジイミド基（−Ｎ＝Ｃ＝Ｎ−）を有する化合物であって、水溶性を有する化合物をいう。水溶性カルボジイミドの具体例としては、１−エチル−３−（３−ジメチルアミノプロピル）カルボジイミド（以下「ＥＤＣ」ともいう。）またはその塩、１−シクロヘキシル−３−（２−モルホリノエチル）カルボジイミド−メト−ｐ−トルエン硫酸またはその塩、ジシクロヘキシルカルボジイミドなどが挙げられ、好ましくは１−エチル−３−（３−ジメチルアミノプロピル）カルボジイミド塩酸塩、１−シクロヘキシル−３−（２−モルホリノエチル）カルボジイミド−メト−ｐ−トルエン硫酸塩である。
縮合剤の使用量は、使用される架橋剤１モルに対し、０〜５０モル、好ましくは１〜４０モル、より好ましくは２〜３０モルである。 A condensing agent and a condensing aid may be used in combination with the crosslinking agent. When a condensing agent and a condensing aid are used in combination, an amide bond can be formed more efficiently.
A water-soluble carbodiimide is mentioned as a condensing agent. The water-soluble carbodiimide is a compound having a carbodiimide group (—N═C═N—) in the molecule and having water solubility. Specific examples of the water-soluble carbodiimide include 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (hereinafter also referred to as “EDC”) or a salt thereof, 1-cyclohexyl-3- (2-morpholinoethyl) carbodiimide- And meth-p-toluenesulfuric acid or a salt thereof, dicyclohexylcarbodiimide, and the like, preferably 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, 1-cyclohexyl-3- (2-morpholinoethyl) carbodiimide- Meto-p-toluene sulfate.
The usage-amount of a condensing agent is 0-50 mol with respect to 1 mol of crosslinking agents used, Preferably it is 1-40 mol, More preferably, it is 2-30 mol.

縮合助剤としては、Ｎ−ヒドロキシイミドが挙げられる。Ｎ−ヒドロキシイミドとは、分子内にＮ−ヒドロキシイミド基（−（Ｃ＝Ｏ）−（Ｎ−ＯＨ）−（Ｃ＝Ｏ）−）を有する化合物である。すなわち、この化合物は、次の一般式で表される。
Ｒ１−（Ｃ＝Ｏ）−（Ｎ−ＯＨ）−（Ｃ＝Ｏ）−Ｒ２
ここで、Ｒ１およびＲ２が結合することにより、環構造が形成されてもよい。Ｒ１およびＲ２が結合してＲ１およびＲ２中の２つの炭素とＮ−ヒドロキシイミド基とで５員環を形成した化合物が好ましい。また、Ｎ−ヒドロキシイミドは、水溶性であることが好ましい。使用可能なＮ−ヒドロキシイミドの具体例としては、Ｎ−ヒドロキシコハク酸イミド、Ｎ−ヒドロキシマレイン酸イミド、Ｎ−ヒドロキシへキサヒドロフタル酸イミド、Ｎ，Ｎ′−ジヒドロキシシクロヘキサンテトラカルボン酸イミド、Ｎ−ヒドロキシフタル酸イミド、Ｎ−ヒドロキシテトラブロモフタル酸イミド、Ｎ−ヒドロキシテトラクロロフタル酸イミド、Ｎ−ヒドロキシヘット酸イミド、Ｎ−ヒドロキシハイミック酸イミド、Ｎ−ヒドロキシトリメリット酸イミド、Ｎ，Ｎ′−ジヒドロキシピロメリット酸イミド、Ｎ，Ｎ′−ジヒドロキシナフタレンテトラカルボン酸イミドが挙げられる。Ｎ−ヒドロキシイミドの中でも、Ｎ−ヒドロキシコハク酸イミド（以下「ＮＨＳ」ともいう。）が最も好ましい。
縮合助剤の使用量は、使用される架橋剤１モルに対し、０〜５０モル、好ましくは１〜４０モル、さらに好ましくは２〜３０モルである。なお、縮合助剤の使用量は、使用される縮合剤の使用量と等モルとすることが好ましい。 N-hydroxyimide is mentioned as a condensation adjuvant. N-hydroxyimide is a compound having an N-hydroxyimide group (— (C═O) — (N—OH) — (C═O) —) in the molecule. That is, this compound is represented by the following general formula.
R 1 - (C = O) - (N-OH) - (C = O) -R 2
Here, a ring structure may be formed by combining R 1 and R 2 . A compound in which R 1 and R 2 are combined to form a 5-membered ring with two carbons in R 1 and R 2 and an N-hydroxyimide group is preferable. Moreover, it is preferable that N-hydroxyimide is water-soluble. Specific examples of N-hydroxyimide that can be used include N-hydroxysuccinimide, N-hydroxymaleimide, N-hydroxyhexahydrophthalimide, N, N'-dihydroxycyclohexanetetracarboxylic imide, N -Hydroxyphthalic acid imide, N-hydroxytetrabromophthalic acid imide, N-hydroxytetrachlorophthalic acid imide, N-hydroxyhetic acid imide, N-hydroxyhymic acid imide, N-hydroxytrimellitic acid imide, N, N Examples include '-dihydroxypyromellitic imide and N, N'-dihydroxynaphthalene tetracarboxylic imide. Among N-hydroxyimides, N-hydroxysuccinimide (hereinafter also referred to as “NHS”) is most preferable.
The usage-amount of a condensation adjuvant is 0-50 mol with respect to 1 mol of crosslinking agents used, Preferably it is 1-40 mol, More preferably, it is 2-30 mol. In addition, it is preferable that the usage-amount of a condensation adjuvant shall be equimolar with the usage-amount of the condensing agent used.

天然由来高分子を架橋させる際の天然由来高分子の濃度は、好ましくは１〜４０質量％であり、より好ましくは２〜２０質量％であり、さらに好ましくは３〜１５質量％である。天然由来高分子の濃度が高すぎると、得られるヒドロゲルの粘度が高くなり、撹拌が困難になるおそれがある。天然由来高分子の濃度が低すぎると、複合品の回収量が低く生産性が悪くなる。   The density | concentration of the natural origin polymer at the time of bridge | crosslinking a natural origin polymer becomes like this. Preferably it is 1-40 mass%, More preferably, it is 2-20 mass%, More preferably, it is 3-15 mass%. If the concentration of the naturally-derived polymer is too high, the resulting hydrogel has a high viscosity and may be difficult to stir. If the concentration of the naturally derived polymer is too low, the recovered amount of the composite product is low and the productivity is deteriorated.

架橋工程の条件は特に限定されない。室温でもよく、加温してもよい。ただし、温度が低すぎる場合には、架橋反応に極めて長時間を有するので、加熱を行うことが好ましい。架橋工程の温度は、好ましくは１０〜１００℃であり、より好ましくは１５〜７０℃であり、さらに好ましくは２０℃〜５０℃である。高すぎる場合には、天然由来高分子が分解しやすい。従って室温付近で行うことが好ましい。架橋反応の際のｐＨは特に限定されないが、好ましくは５〜１２であり、より好ましくは６〜１１であり、さらに好ましくは７〜１０である。   The conditions for the crosslinking step are not particularly limited. It may be room temperature or may be heated. However, if the temperature is too low, the crosslinking reaction takes a very long time, so it is preferable to perform heating. The temperature in the crosslinking step is preferably 10 to 100 ° C, more preferably 15 to 70 ° C, and further preferably 20 ° C to 50 ° C. When it is too high, the naturally-derived polymer is easily decomposed. Therefore, it is preferable to carry out at around room temperature. Although the pH in the case of a crosslinking reaction is not specifically limited, Preferably it is 5-12, More preferably, it is 6-11, More preferably, it is 7-10.

架橋工程の反応時間は、好ましくは５分〜６時間であり、より好ましくは１０分〜３時間であり、さらに好ましくは２０分〜２時間である。架橋反応の際には、必要に応じて、反応溶液を攪拌してもよく、静置しておいてもよい。好ましくは、静置しておく。架橋反応に充分な時間が経過した後、反応溶液中にゲルが得られる。この反応溶液を水（好ましくは蒸留水）で洗うことにより、反応溶液中の縮合剤および縮合助剤が除去され、天然由来高分子が架橋剤で架橋されたゲルが得られる。   The reaction time in the crosslinking step is preferably 5 minutes to 6 hours, more preferably 10 minutes to 3 hours, and further preferably 20 minutes to 2 hours. In the crosslinking reaction, the reaction solution may be stirred or allowed to stand as necessary. Preferably, it is left still. After sufficient time for the crosslinking reaction, a gel is obtained in the reaction solution. By washing this reaction solution with water (preferably distilled water), the condensing agent and the condensation aid in the reaction solution are removed, and a gel in which the naturally derived polymer is crosslinked with a crosslinking agent is obtained.

次に、天然由来高分子を架橋する工程において得られた架橋した天然由来高分子を含むヒドロゲルを湿式粉砕する（粉砕工程）。この工程では、ヒドロゲルは、含水状態で所望の大きさに粉砕される（すなわち湿式粉砕）。粉砕は、予め粗粉砕した後、本粉砕することが好ましい。粗粉砕は、架橋反応により得られたヒドロゲルを、たとえば、スパーテルなどで撹拌することにより行われる。本粉砕では、ヒドロゲルは、たとえば、ホモミキサー、ホモジナイザー、ビーズミル、パイプミキサーなどの湿式粉砕に適する装置を用いて粉砕される。本明細書において、粉砕されたヒドロゲルを、ヒドロゲル粒子という。ヒドロゲル粒子の平均粒子径は、最終的に得られる乾燥ゲル粉末の用途によって、あるいは粉砕に用いる装置に応じて適宜設定され得るが、好ましくは１０μｍ〜１０ｍｍ、より好ましくは、１００μｍ〜３ｍｍである。   Next, the hydrogel containing the cross-linked naturally-derived polymer obtained in the step of cross-linking the naturally-derived polymer is wet-pulverized (pulverizing step). In this step, the hydrogel is pulverized to a desired size in a water-containing state (ie, wet pulverization). The pulverization is preferably carried out after coarse pulverization in advance. Coarse pulverization is performed by stirring the hydrogel obtained by the crosslinking reaction with, for example, a spatula. In the main pulverization, the hydrogel is pulverized using an apparatus suitable for wet pulverization such as a homomixer, a homogenizer, a bead mill, and a pipe mixer. In this specification, the ground hydrogel is referred to as hydrogel particles. The average particle size of the hydrogel particles can be appropriately set depending on the use of the finally obtained dry gel powder or according to the apparatus used for pulverization, but is preferably 10 μm to 10 mm, more preferably 100 μm to 3 mm.

ヒドロゲルの粘度が高く、粉砕が困難である場合、後述する水混和性有機溶媒を加えてもよい。すなわち、水混和性有機溶媒を加えた後に粉砕してもよい。水混和性有機溶媒を加えることによって、ヒドロゲルは脱水されて減容（収縮）し、湿式粉砕中の分散液の粘度が低くなり、流動性が回復する。粉砕中に増粘した場合も、途中で水混和性有機溶媒を添加して、粉砕を続けることができる。このように、湿式粉砕工程と後述の脱水工程とが同時に行われてもよい。   When the hydrogel has a high viscosity and is difficult to grind, a water-miscible organic solvent described later may be added. That is, you may grind | pulverize, after adding a water miscible organic solvent. By adding a water-miscible organic solvent, the hydrogel is dehydrated and volume-reduced (shrinks), the viscosity of the dispersion during wet grinding is lowered, and fluidity is restored. Even when the viscosity is increased during the pulverization, the water-miscible organic solvent can be added on the way to continue the pulverization. Thus, the wet pulverization step and the dehydration step described later may be performed simultaneously.

カルボキシル基を有する天然由来高分子を原料として用いる場合、上記のように、天然由来高分子のカルボキシル基部分を、ナトリウム塩などの水溶性の塩形態にして、ヒドロゲルが調製される。しかし、塩形態のヒドロゲルを乾燥ゲル粉末にした場合、大気中で吸湿して粉末同士が合着するおそれがある。したがって、ヒドロゲルを調製後、無機酸または有機酸を加えて一部を塩形態から遊離酸形態にしてもよい。遊離酸形態のヒドロゲルから得られた乾燥ゲル粉末は、塩形態の乾燥ゲル粉末と比べて吸湿性が低減され、そのため粉末同士の合着が起こりにくい。無機酸および有機酸としては、たとえば、硫酸、塩酸、硝酸、ｐ−トルエンスルホン酸などが挙げられる。無機酸または有機酸は、水混和性有機溶媒と混合してヒドロゲル粒子に加えることが好ましい。無機酸または有機酸を加えると、ヒドロゲルが均一に中和され、均一な遊離酸形態のヒドロゲル粒子が得られるからである。   When a naturally derived polymer having a carboxyl group is used as a raw material, a hydrogel is prepared by converting the carboxyl group portion of the naturally derived polymer into a water-soluble salt form such as a sodium salt as described above. However, when salt-form hydrogels are made into dry gel powders, they may absorb moisture in the atmosphere and the powders may coalesce. Therefore, after preparing the hydrogel, an inorganic acid or an organic acid may be added to partially change the salt form to the free acid form. The dry gel powder obtained from the hydroacid in the free acid form has reduced hygroscopicity compared to the dry gel powder in the salt form, so that the powders are less likely to coalesce. As an inorganic acid and an organic acid, a sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid etc. are mentioned, for example. The inorganic acid or organic acid is preferably mixed with a water-miscible organic solvent and added to the hydrogel particles. This is because when an inorganic acid or an organic acid is added, the hydrogel is uniformly neutralized to obtain hydrogel particles in a uniform free acid form.

次に、湿式粉砕したヒドロゲルに水混和性有機溶媒を加え、ヒドロゲルを脱水する（脱水工程）。ヒドロゲル粒子を水混和性有機溶媒に浸漬させると、ヒドロゲル粒子中に含まれる水が、水混和性有機溶媒中に排出される。ヒドロゲル粒子は脱水されて、微粒子サイズに収縮する場合もある。さらに、天然由来高分子を架橋させるために用いた未反応の架橋剤、縮合剤などの不要物質も、ヒドロゲル粒子中から水とともに排出される。   Next, a water-miscible organic solvent is added to the wet-ground hydrogel to dehydrate the hydrogel (dehydration step). When the hydrogel particles are immersed in the water-miscible organic solvent, the water contained in the hydrogel particles is discharged into the water-miscible organic solvent. The hydrogel particles may be dehydrated and shrink to a fine particle size. Furthermore, unnecessary substances such as unreacted crosslinking agents and condensing agents used for crosslinking the naturally derived polymer are also discharged together with water from the hydrogel particles.

水混和性有機溶媒は、特に限定されない。たとえば、メタノール、エタノール、イソプロパノール、ｎ−プロパノール、第三級ブタノールなどの低級アルコール類、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、エチレングリコールモノイソプロピルエーテル、プロピレングリコールモノメチルエーテル、プロピレングリコールモノエチルエーテルなどのグリコールエーテル類、およびアセトンが挙げられる。これらの中でも、メタノール、エタノール、イソプロパノール、およびアセトンが好ましい。これらの水混和性有機溶媒は、単独で用いてもよく、２種以上を混合して用いてもよく、あるいは２種以上の溶媒を分散状態に応じて、逐次的に加えてもよい。   The water miscible organic solvent is not particularly limited. For example, lower alcohols such as methanol, ethanol, isopropanol, n-propanol, tertiary butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc. Glycol ethers, and acetone. Among these, methanol, ethanol, isopropanol, and acetone are preferable. These water-miscible organic solvents may be used singly or in combination of two or more, or two or more solvents may be added sequentially according to the dispersion state.

水混和性有機溶媒へのヒドロゲル粒子の浸漬は、数回繰り返してもよい。この場合、ヒドロゲル粒子から排出された水を含む溶媒を、ろ過またはデカンテーションで除去し、新しく水混和性有機溶媒をヒドロゲル粒子に加える。このように数回の浸漬を繰り返すことによって、ヒドロゲル粒子は、より脱水されて収縮し、非常に含水率の低い微粒子となる。数回の浸漬を繰り返す場合、１回の浸漬ごとに異なる水混和性有機溶媒を用いてもよい。   The immersion of the hydrogel particles in the water-miscible organic solvent may be repeated several times. In this case, the solvent containing water discharged from the hydrogel particles is removed by filtration or decantation, and a new water-miscible organic solvent is added to the hydrogel particles. By repeating the immersion several times in this manner, the hydrogel particles are dehydrated and contracted to become fine particles having a very low water content. When repeating soaking several times, a different water-miscible organic solvent may be used for each soaking.

水混和性有機溶媒の使用量は、その種類、ヒドロゲル調製時の水の量などに応じて異なるが、１回あたりの浸漬につき、ヒドロゲルに対して好ましくは１倍容量（等量）〜２０倍容量であり、より好ましくは２倍容量〜１０倍容量であり、さらに好ましくは３倍容量〜７倍容量である。
ヒドロゲル粒子を水混和性有機溶媒に浸漬させる時間は、溶媒の種類、量などに応じて異なるが、１回あたりの浸漬につき、作業性を考慮すると、好ましくは１分〜２時間であり、より好ましくは２分〜１時間であり、さらに好ましくは３分〜３０分である。
必要に応じて、水混和性有機溶媒に浸漬後のヒドロゲル粒子を、適切な液体でリンスしてもよい。 The amount of water-miscible organic solvent used varies depending on the type, the amount of water at the time of hydrogel preparation, etc., but preferably 1-fold volume (equal amount) to 20-fold with respect to the hydrogel per immersion. The capacity is more preferably 2 times capacity to 10 times capacity, and further preferably 3 times capacity to 7 times capacity.
The time for immersing the hydrogel particles in the water-miscible organic solvent varies depending on the type and amount of the solvent, but it is preferably 1 minute to 2 hours in consideration of workability per one immersion. It is preferably 2 minutes to 1 hour, more preferably 3 minutes to 30 minutes.
If necessary, the hydrogel particles immersed in a water-miscible organic solvent may be rinsed with an appropriate liquid.

次に、脱水したヒドロゲルを乾燥する（乾燥工程）。脱水工程後に得られるヒドロゲル粒子は、含水率が低く、ほとんど水分は含まれていない。したがって、ろ過またはデカンテーションによって、水混和性有機溶媒を除去し、好ましくは室温〜１５０℃、より好ましくは３５℃〜１２５℃、さらに好ましくは５０℃〜１００℃で送風乾燥または静置乾燥することにより、乾燥ゲル粉末が得られる。このように、ヒドロゲル粒子は、過酷な乾燥条件に曝されることがないので、乾燥中に粒子同士が合着することもない。   Next, the dehydrated hydrogel is dried (drying step). The hydrogel particles obtained after the dehydration step have a low water content and hardly contain moisture. Therefore, the water-miscible organic solvent is removed by filtration or decantation, and is preferably blown or statically dried at room temperature to 150 ° C, more preferably 35 ° C to 125 ° C, and even more preferably 50 ° C to 100 ° C. Thus, a dry gel powder is obtained. Thus, since the hydrogel particles are not exposed to severe drying conditions, the particles do not coalesce during drying.

得られる乾燥ゲル粉末の粒子径は、乾燥ゲル粉末の用途などを考慮して決定することができ、特に限定されない。すなわち、上記の粉砕工程において用いられる粉砕装置（ホモミキサー、ホモジナイザーなど）およびその粉砕力に応じて、所望の粒子径を有する乾燥ゲル粉末を得ることができる。   The particle diameter of the obtained dry gel powder can be determined in consideration of the use of the dry gel powder and the like, and is not particularly limited. That is, a dry gel powder having a desired particle size can be obtained according to the pulverization apparatus (homomixer, homogenizer, etc.) used in the above pulverization step and the pulverization force thereof.

一般に、ポリマーが網目構造（ゲル状態）を保持していない場合には、ポリマーは、溶媒に浸すと溶解してしまう。しかし、上記の方法で得られる乾燥ゲル粉末は、水に浸すと溶解せずに膨潤し、ヒドロゲルを再生する。したがって、上記の方法で得られる乾燥ゲル粉末は、網目構造（ゲル状態）を保持している。   Generally, when a polymer does not maintain a network structure (gel state), the polymer is dissolved when immersed in a solvent. However, the dry gel powder obtained by the above method swells without dissolving when immersed in water, and regenerates the hydrogel. Therefore, the dry gel powder obtained by the above method retains a network structure (gel state).

実施例１
γ−ＰＧＡ（Ｎａ型，５００ＫＤａ，株式会社バイオリーダーズ製）１．３５９ｇ（グルタミン酸ユニット９ｍｍｏｌ（γ−ＰＧＡを構成するグルタミン酸１ユニットは１５１ｇ／ｍｏｌである。））をイオン交換水に溶解し、水溶液を調製した。次いで、セルロースナノファイバー５％水分散液（ＢｉＮＦｉ−ｓ ＮＭａ，平均重合度５３０，平均直径０．０２μｍ，平均長さ２μｍ，株式会社スギノマシン製）を３．０２ｇ（γ−ＰＧＡとセルロースナノファイバーの合計量に対して１０質量％）添加し、固形分濃度７質量％の分散液を調製し、ホモジナイザー（ＡＨＧ−１６０Ｄ，シャフトジェネレーターＨＴ１０１８，アズワン株式会社製）を用いて１０００ｒｐｍの条件で混合した。
次いで、ペンタエチレンヘキサミン（和光純薬工業株式会社製）を対グルタミン酸ユニット２ｍｏｌ％、Ｎ−ヒドロキシコハク酸イミド（以下「ＮＨＳ」ともいう。）（和光純薬工業株式会社製）を対グルタミン酸ユニット６ｍｏｌ％、１−エチル−３−（３−ジメチルアミノプロピル）カルボジイミド（以下「ＥＤＣ」ともいう。）塩酸塩（和光純薬工業株式会社製）を対グルタミン酸ユニット６ｍｏｌ％で順次攪拌しながら加えた。３分程度で白濁したヒドロゲルが得られた。
添加終了３０分後、得られた白濁ヒドロゲルをスパーテルで粗粉砕した。次いで、粗粉砕したヒドロゲルに２０ｇのメタノール（和光純薬工業株式会社製）を加え、ホモジナイザー（ＡＨＧ−１６０Ｄ，シャフトジェネレーターＨＴ１０１８，アズワン株式会社製）を用いて７５０ｒｐｍの条件で湿式粉砕した。湿式粉砕後、分散液を静置すると、半透明なヒドロゲル粒子が沈降するので、デカンテーションにより溶媒を除去し、新たに２０ｇのメタノールを加え攪拌した。一連の操作を繰り返し、ヒドロゲル粒子が収縮して白色粒子になるまで脱水を行なった。
脱水した粒子を７０℃、９０分の条件で送風乾燥し、乾燥ゲル粉末を得た。
得られた乾燥ゲル粉末を、吸水剤として、後述の方法により、ゲル強度および保水容量を測定した。測定結果を表１に示す。 Example 1
1.359 g of γ-PGA (Na type, 500 KDa, manufactured by BioLeaders Co., Ltd.) (9 mmol of glutamic acid unit (1 unit of glutamic acid constituting γ-PGA is 151 g / mol)) is dissolved in ion-exchanged water to obtain an aqueous solution. Was prepared. Subsequently, 3.02 g ( γ-PGA and cellulose nanofiber ) of 5% aqueous dispersion of cellulose nanofiber (BiNFi-s NMa, average polymerization degree 530, average diameter 0.02 μm, average length 2 μm, manufactured by Sugino Machine Co., Ltd.) 10% by mass with respect to the total amount ), and a dispersion having a solid content concentration of 7% by mass was prepared and mixed at 1000 rpm using a homogenizer (AHG-160D, shaft generator HT1018, manufactured by ASONE Co., Ltd.). .
Subsequently, pentaethylenehexamine (manufactured by Wako Pure Chemical Industries, Ltd.) is 2 mol% for glutamic acid unit, and N-hydroxysuccinimide (hereinafter also referred to as “NHS”) (manufactured by Wako Pure Chemical Industries, Ltd.) is 6 mol of glutamic acid unit. %, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (hereinafter also referred to as “EDC”) hydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the glutamic acid unit at 6 mol% with sequential stirring. A cloudy hydrogel was obtained in about 3 minutes.
30 minutes after completion of the addition, the resulting cloudy hydrogel was coarsely pulverized with a spatula. Next, 20 g of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the coarsely pulverized hydrogel, and wet pulverized using a homogenizer (AHG-160D, shaft generator HT1018, manufactured by ASONE Corporation) at 750 rpm. After the wet pulverization, when the dispersion was allowed to stand, translucent hydrogel particles settled. The solvent was removed by decantation, and 20 g of methanol was newly added and stirred. A series of operations was repeated, and dehydration was performed until the hydrogel particles contracted to become white particles.
The dehydrated particles were blown and dried at 70 ° C. for 90 minutes to obtain a dry gel powder.
Using the obtained dried gel powder as a water-absorbing agent, gel strength and water retention capacity were measured by the methods described later. The measurement results are shown in Table 1.

比較例１
γ−ＰＧＡを１．５１ｇ（グルタミン酸ユニット１０ｍｍｏｌ）使用し、セルロースナノファイバーを添加せずに、他は実施例１と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表１に示す。 Comparative Example 1
Using 1.51 g of γ-PGA (glutamate unit 10 mmol) and adding no cellulose nanofibers, a water-absorbing agent was prepared in the same manner as in Example 1, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 1.

比較例２
セルロースナノファイバーの代わりに、微細セルロース原料であるセルロースパウダー（「ＫＣフロック」（登録商標）Ｗ−５０ＧＫ，平均重合度５３０，平均直径２５μｍ，平均長さ４５μｍ，日本製紙ケミカル株式会社製）を用い、他は実施例１と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表１に示す。 Comparative Example 2
Instead of cellulose nanofiber, cellulose powder ("KC Flock" (registered trademark) W-50GK, average degree of polymerization 530, average diameter 25 μm, average length 45 μm, manufactured by Nippon Paper Chemical Co., Ltd.), which is a fine cellulose raw material, is used. Other than that, a water-absorbing agent was prepared in the same procedure as in Example 1, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 1.

実施例２
セルロースナノファイバー５％水分散液をＢｉＮＦｉ−ｓ ＮＭａからＢｉＮＦｉ−ｓ ＡＭａ（平均重合度２００，平均直径０．０２μｍ，平均長さ２μｍ，株式会社スギノマシン製）に変更し、他は実施例１と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表１に示す。 Example 2
The cellulose nanofiber 5% aqueous dispersion was changed from BiNFi-s NMa to BiNFi-s AMa (average polymerization degree 200, average diameter 0.02 μm, average length 2 μm, manufactured by Sugino Machine Co., Ltd.). In the same procedure as described above, a water-absorbing agent was prepared, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 1.

実施例３
セルロースナノファイバー５％水分散液をＢｉＮＦｉ−ｓ ＮＭａからＢｉＮＦｉ−ｓ ＦＭａ（平均重合度６００，平均直径０．０２μｍ，平均長さ２μｍ，株式会社スギノマシン製）に変更し、他は実施例１と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表１に示す。 Example 3
The cellulose nanofiber 5% aqueous dispersion was changed from BiNFi-s NMa to BiNFi-s FMa (average polymerization degree 600, average diameter 0.02 μm, average length 2 μm, manufactured by Sugino Machine Co., Ltd.). In the same procedure as described above, a water-absorbing agent was prepared, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 1.

実施例４
γ−ＰＧＡを分子量が５０ＫＤａのもの（株式会社バイオリーダーズ製）に変更し、他は実施例１と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表１に示す。 Example 4
γ-PGA was changed to one having a molecular weight of 50 KDa (manufactured by BioReaders Co., Ltd.), and a water absorbing agent was prepared in the same procedure as in Example 1, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 1.

実施例５
γ−ＰＧＡを分子量が２０００ＫＤａのもの（株式会社バイオリーダーズ製）に変更し、他は実施例１と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表１に示す。 Example 5
γ-PGA was changed to one having a molecular weight of 2000 KDa (manufactured by Bioleaders Co., Ltd.), and a water absorbing agent was prepared in the same procedure as in Example 1, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 1.

実施例６
γ−ＰＧＡを分子量が２０００ＫＤａのもの（株式会社バイオリーダーズ製）に変更し、かつ微細セルロースファイバー５％水分散液をＢｉＮＦｉ−ｓ ＮＭａからＢｉＮＦｉ−ｓ ＦＭａに変更し、他は実施例１と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表２に示す。 Example 6
The γ-PGA was changed to one having a molecular weight of 2000 KDa (manufactured by BioLeaders Co., Ltd.), and the fine cellulose fiber 5% aqueous dispersion was changed from BiNFi-s NMa to BiNFi-s FMa. The water absorbing agent was prepared by the procedure described above, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 2.

実施例７
セルロースナノファイバーの添加量をγ−ＰＧＡとセルロースナノファイバーの合計量に対して２０質量％に変更し、他は実施例６と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表２に示す。 Example 7
The addition amount of cellulose nanofibers was changed to 20% by mass with respect to the total amount of γ-PGA and cellulose nanofibers , and a water absorbing agent was prepared in the same manner as in Example 6, and the gel strength and water retention capacity were adjusted. It was measured. The measurement results are shown in Table 2.

実施例８
セルロースナノファイバーの添加量をγ−ＰＧＡとセルロースナノファイバーの合計量に対して３０質量％に変更し、他は実施例６と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表２に示す。 Example 8
The amount of cellulose nanofiber added was changed to 30% by mass with respect to the total amount of γ-PGA and cellulose nanofiber , and the other procedures were the same as in Example 6 to prepare a water absorbing agent, and the gel strength and water retention capacity were adjusted. It was measured. The measurement results are shown in Table 2.

比較例３
セルロースナノファイバーを添加せずに、他は実施例６と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表２に示す。 Comparative Example 3
A water-absorbing agent was prepared in the same manner as in Example 6 except that cellulose nanofibers were not added, and gel strength and water retention capacity were measured. The measurement results are shown in Table 2.

比較例４
架橋剤であるペンタエチレンヘキサミンの添加量を対ＰＧＡ６ｍｏｌ％に変更し、他は比較例３と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表２に示す。 Comparative Example 4
A water absorbing agent was prepared in the same manner as in Comparative Example 3 except that the amount of addition of pentaethylenehexamine as a cross-linking agent was changed to 6 mol% with respect to PGA, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 2.

比較例５
架橋剤であるペンタエチレンヘキサミンの添加量を対ＰＧＡ９ｍｏｌ％に変更し、他は比較例３と同様の手順で、吸水剤を調製し、ゲル強度および保水容量を測定した。測定結果を表２に示す。 Comparative Example 5
A water-absorbing agent was prepared in the same manner as in Comparative Example 3 except that the addition amount of pentaethylenehexamine as a cross-linking agent was changed to 9 mol% relative to PGA, and the gel strength and water retention capacity were measured. The measurement results are shown in Table 2.

比較例６
市販のアクリル酸系ＳＡＰ（住友精化株式会社製アクアキープＳＡ６０Ｓ）についてゲル強度および保水容量を測定した。測定結果を表２に示す。 Comparative Example 6
Gel strength and water retention capacity were measured for a commercially available acrylic acid SAP (Aquakeep SA60S manufactured by Sumitomo Seika Co., Ltd.). The measurement results are shown in Table 2.

［保水容量測定］
（１）２５０メッシュナイロンネット（株式会社ＮＢＣメッシュテック製 Ｎ−ＮＯ．２５０ＨＤ）で袋（１０×２０ｃｍ）を準備し、測定サンプル０．３ｇを入れる。
（２）ナイロンネットを含む質量Ａを測定する。
（３）ビーカーに生理食塩水１Ｌを入れ、準備したサンプル入りのナイロンネットを浸漬させ、１時間放置する。
（４）袋を引き上げ、袋短辺を洗濯ばさみではさんで吊り下げ、１５分間水切りを行う。
（５）さらに遠心分離機で脱水する（１５０Ｇ，９０秒）。
（６）脱水後の質量Ｂを測定する。
（７）保水容量（ｇ／ｇ）を次式により算出する。
保水容量＝（Ｂ−Ａ）／０．３ [Water retention capacity measurement]
(1) A bag (10 × 20 cm) is prepared with a 250 mesh nylon net (N-NO.250HD manufactured by NBC Meshtec Co., Ltd.), and 0.3 g of a measurement sample is put therein.
(2) The mass A including the nylon net is measured.
(3) Put 1 L of physiological saline into a beaker, immerse the prepared nylon net containing the sample, and leave it for 1 hour.
(4) Pull up the bag, hang the short side of the bag with clothespins, and drain for 15 minutes.
(5) Further dehydrate with a centrifuge (150 G, 90 seconds).
(6) The mass B after dehydration is measured.
(7) The water retention capacity (g / g) is calculated by the following formula.
Water retention capacity = (B−A) /0.3

［ゲル強度測定］
（１）保水容量測定と同様の方法で保水状態のヒドロゲルを準備する。
（２）直径２７ｍｍのＰＰチューブ（ニューＰＰサンプル管ＮＯ．５，２２ｍＬ，株式会社マルエム製）にサンプル６．０ｇを入れる。
（３）サンプルの上に直径２５ｍｍのメッシュをおく。
（４）デジタルフォースゲージでメッシュを押す（侵入速度１ｍｍ／ｓ）。
（５）デジタルフォースゲージの測定値で小数点以下３桁目が動き始めた時点をスタートとし、１０秒間（１０ｍｍ）ゲルを押した際の最大荷重の数値を読み取り、ゲル強度とする。 [Gel strength measurement]
(1) A water-retaining hydrogel is prepared by the same method as the water retention capacity measurement.
(2) 6.0 g of sample is put into a PP tube (new PP sample tube NO. 5, 22 mL, manufactured by Marmu Co., Ltd.) having a diameter of 27 mm.
(3) A 25 mm diameter mesh is placed on the sample.
(4) Push the mesh with a digital force gauge (penetration speed 1 mm / s).
(5) Start from the time when the third digit after the decimal point starts to move in the measured value of the digital force gauge, and read the value of the maximum load when the gel is pressed for 10 seconds (10 mm) to obtain the gel strength.

セルロースについてナノ粉砕されているものとされていないものの比較（Ｗ−５０ＧＫとＮＭａ）では、ナノ粉砕されているものではゲル強度の向上効果が見られる一方で、粉砕されていないものではゲル強度の向上は見られなかった。
セルロースナノファイバーの平均重合度違いの比較（ＡＭａ＜ＮＭａ＜ＦＭａ）では重合度の大きいものの方がゲル強度の向上効果は高い傾向があった。
また、セルロースナノファイバーの平均重合度によってゲル強度が異なる結果になったのに対して、保水容量については複合材の平均重合度によっての違いは見られなかった。
ゲル強度を上げる目的としては重合度の大きいセルロースナノファイバーを添加するのが良いことが分かる。 In comparison of cellulose nano-pulverized and non-pulverized cellulose (W-50GK and NMa), nano-pulverized ones show an effect of improving gel strength, while non-pulverized ones exhibit gel strength improvement. There was no improvement.
In comparison of the difference in the average degree of polymerization of cellulose nanofibers (AMa <NMa <FMa), the effect of improving the gel strength tended to be higher when the degree of polymerization was higher.
In addition, the gel strength was different depending on the average degree of polymerization of the cellulose nanofibers, whereas the water retention capacity was not different depending on the average degree of polymerization of the composite material.
It can be seen that for the purpose of increasing the gel strength, it is better to add cellulose nanofibers having a high degree of polymerization.

セルロースナノファイバー１０％混の条件において天然由来高分子のポリグルタミン酸の平均分子量違いの比較では平均分子量の大きいものの方がゲル強度が大きくなる傾向があった。
保水容量の結果において天然由来高分子のポリグルタミン酸の平均分子量が小さいものでは液の保持性が低くなる傾向があった。また、逆に平均分子量の大きいものではゲル強度の向上が見られた一方で、保水容量については平均分子量が中程度のものに対して低下する傾向が見られた。
ゲル強度を上げる目的としては平均分子量の大きいポリグルタミン酸を用いるのが良いことが分かる。 In the comparison of the average molecular weight difference of the polyglutamic acid, which is a naturally derived polymer, under the condition of 10% cellulose nanofiber mixture, the gel strength tended to increase with the higher average molecular weight.
As a result of the water retention capacity, when the average molecular weight of the polyglutamic acid, which is a naturally derived polymer, is small, the liquid retention tends to be low. On the other hand, the gel strength was improved in the case where the average molecular weight was large, while the water retention capacity tended to be lower than that in the middle where the average molecular weight was medium.
It can be seen that for the purpose of increasing the gel strength, it is better to use polyglutamic acid having a large average molecular weight.

架橋剤のみでゲル物性をコントロールする場合、合成時の架橋剤濃度を高くしすぎるとかえってゲル強度は低くなる傾向がある。同様にセルロースナノファイバーの添加量を増やしてゲル強度を上げる場合においても添加量を増加させすぎるとゲル強度は低くなる傾向がある（定性的には伸度がなくなり脆い状態になる）。
架橋剤濃度を増加させてゲル強度を上げた場合に対して、セルロースの添加によってゲル強度を上げた場合の方が保水容量の低下度合いは低いことが分かる。 When the gel physical properties are controlled only by the crosslinking agent, the gel strength tends to be lowered if the crosslinking agent concentration at the time of synthesis is excessively increased. Similarly, when the gel strength is increased by increasing the addition amount of cellulose nanofibers, the gel strength tends to decrease if the addition amount is excessively increased (qualitatively, the elongation is lost and the state becomes brittle).
It can be seen that when the gel strength is increased by increasing the concentration of the crosslinking agent, the degree of decrease in the water retention capacity is lower when the gel strength is increased by adding cellulose.

本発明の吸水剤は、使い捨ておむつ、生理用ナプキン等の吸収性物品の吸収体を構成する原材料として好適に用いることができる。   The water-absorbing agent of the present invention can be suitably used as a raw material constituting an absorbent body of absorbent articles such as disposable diapers and sanitary napkins.

１ 吸収剤の粒子
２ 架橋した天然由来高分子
３ バイオマスナノファイバー 1 Absorbent Particles 2 Crosslinked Naturally Derived Polymer 3 Biomass Nanofiber

Claims (4)

架橋した天然由来高分子およびバイオマスナノファイバーからなる吸水剤を製造する方法であって、前記方法は、
天然由来高分子を溶解し、天然由来高分子の溶液を調製する工程、
天然由来高分子の溶液にバイオマスナノファイバーを分散させ、バイオマスナノファイバーが分散した天然由来高分子の溶液を調製する工程、および
バイオマスナノファイバーが分散した天然由来高分子の溶液に架橋剤を添加し、天然由来高分子を架橋する工程
を含み、
天然由来高分子がポリアミノ酸であり、
バイオマスナノファイバーの平均直径が４〜１０００ｎｍであり、
バイオマスナノファイバーの長さは直径の１００倍以上であり、
バイオマスナノファイバーの含有量が天然由来高分子とバイオマスナノファイバーの合計量１００質量部に対し１０〜３０質量部であり、
架橋剤がポリアミンである、方法。 A method for producing a water-absorbing agent comprising a cross-linked naturally-derived polymer and biomass nanofiber, the method comprising:
Dissolving a naturally-derived polymer and preparing a solution of the naturally-derived polymer;
A process of preparing biomass-derived nanofibers in which biomass nanofibers are dispersed by adding biomass nanofibers to a naturally-occurring polymer solution, and adding a cross-linking agent to the naturally-derived polymer solution in which biomass nanofibers are dispersed. , only including the step of crosslinking the naturally occurring polymer,
The naturally occurring polymer is a polyamino acid,
The average diameter of the biomass nanofiber is 4 to 1000 nm,
The length of the biomass nanofiber is more than 100 times the diameter,
The content of the biomass nanofiber is 10 to 30 parts by mass with respect to 100 parts by mass of the total amount of the naturally derived polymer and the biomass nanofiber,
The method wherein the cross-linking agent is a polyamine . 天然由来高分子を架橋する工程において得られた架橋した天然由来高分子を含むヒドロゲルを湿式粉砕する工程をさらに含む請求項１に記載の方法。 The method of claim 1 a hydrogel containing the crosslinked natural origin polymers obtained in the step of crosslinking the naturally occurring polymer, further comprising the step of wet milling. 湿式粉砕したヒドロゲルに水混和性有機溶媒を加え、ヒドロゲルを脱水する工程をさらに含む請求項２に記載の方法。 The method according to claim 2 , further comprising the step of adding a water-miscible organic solvent to the wet-milled hydrogel to dehydrate the hydrogel. 脱水したヒドロゲルを乾燥する工程をさらに含む請求項３に記載の方法。 The method of claim 3 , further comprising the step of drying the dehydrated hydrogel.
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