JPH0726026A - Production of water-absorbing polymer with surface cross-linked - Google Patents
Production of water-absorbing polymer with surface cross-linkedInfo
- Publication number
- JPH0726026A JPH0726026A JP19267493A JP19267493A JPH0726026A JP H0726026 A JPH0726026 A JP H0726026A JP 19267493 A JP19267493 A JP 19267493A JP 19267493 A JP19267493 A JP 19267493A JP H0726026 A JPH0726026 A JP H0726026A
- Authority
- JP
- Japan
- Prior art keywords
- water
- polymer
- weight
- cross
- polymerization
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、衛生材料や農業・園芸
材料等として好適な吸水性ポリマーの製造方法に関し、
詳しくは含水率が４０重量％以上という高い含水率を有
する吸水性ポリマーを用い、これを特定の水溶率を有す
る架橋剤で表面架橋することにより、脱水操作を必要と
することなく、或いは少量の脱水を実施するだけで、表
面近傍のみを効果的に架橋し、飽和吸水量とゲル強度が
共に優れ、かつ、吸水速度が高い吸水性ポリマーを製造
する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a water-absorbent polymer suitable as sanitary materials, agricultural / horticultural materials, etc.
Specifically, a water-absorbing polymer having a high water content of 40% by weight or more is used, and by surface-crosslinking this with a crosslinking agent having a specific water content, a dehydration operation is not required or a small amount of water is used. The present invention relates to a method for producing a water-absorbent polymer that effectively crosslinks only in the vicinity of the surface only by performing dehydration, is excellent in both saturated water absorption amount and gel strength, and has a high water absorption rate.
【０００２】[0002]
【従来の技術及び発明が解決しようとする課題】吸水性
ポリマーは、従来の紙，パルプ，海綿などに代わり、生
理用品，おむつ，使い捨て雑巾などの衛生材料や、農業
・園芸材料等として利用されており、近年、さらに新し
い用途が開けつつある樹脂である。このため、吸水性ポ
リマーに関して種々の技術が開発されている。BACKGROUND OF THE INVENTION Water-absorbent polymers are used as sanitary materials such as sanitary products, diapers and disposable wipes, and agricultural / horticultural materials in place of conventional paper, pulp, sponge, etc. In recent years, it is a resin that is opening up new applications. Therefore, various techniques have been developed for water-absorbent polymers.
【０００３】吸水性ポリマーの性質として、飽和吸水量
と吸水ゲルの強度とは、一般に負の相関があることが知
られている。すなわち、吸水ゲルの強度を上げるために
ポリマー全体の架橋度を高めると、飽和吸水量が低下す
る。逆に飽和吸水量を上げるために架橋度を下げると、
ゲルの強度が低下するだけでなく、表面の濡れ性が悪く
なり、吸水速度も低下する。As a property of the water-absorbing polymer, it is known that the saturated water absorption amount and the strength of the water-absorbing gel generally have a negative correlation. That is, when the degree of crosslinking of the entire polymer is increased to increase the strength of the water-absorbing gel, the saturated water absorption amount decreases. Conversely, if the degree of cross-linking is lowered to increase the saturated water absorption,
Not only does the strength of the gel decrease, the wettability of the surface deteriorates, and the water absorption rate also decreases.
【０００４】この問題点を改良するため、これまでに重
合後のポリマーの含水率を特定範囲に調節した後、架橋
剤を添加し、ポリマーの表面近傍のみの架橋度を上げる
方法が提案されている。例えば特公昭６０−１８６９０
号公報には、２個以上の官能基を有する架橋剤を用いて
水の存在下、不活性溶媒中で架橋せしめることが記載さ
れており、具体的には含水率が、およそ１〜５６．５重
量％（ポリマー１重量部に対し、水分０．０１〜１．３
重量部）の範囲で表面架橋する技術が記載されている。
また、特開昭６０−１８６５０６号公報には、保護コロ
イドとしてセルロースエステルなどを用い、水分含量が
１０〜４０重量％となるように調整した後、２個以上の
官能基を有する架橋剤を用いて架橋せしめることが記載
されている。さらに、特開昭６３−６１００５号公報に
は、含水量が４０重量％以下の親水性多孔性ポリマーを
架橋剤で表面架橋することが記載されている。In order to improve this problem, there has been proposed a method of adjusting the water content of the polymer after polymerization to a specific range and then adding a crosslinking agent to increase the crosslinking degree only in the vicinity of the surface of the polymer. There is. For example, Japanese Patent Publication No. 60-18690
Japanese Patent Laid-Open Publication No. 2003-242242 describes that crosslinking is carried out in an inert solvent in the presence of water using a crosslinking agent having two or more functional groups. Specifically, the water content is about 1 to 56. 5% by weight (water content 0.01 to 1.3 relative to 1 part by weight of polymer)
The technique of surface cross-linking in the range of (parts by weight) is described.
Further, in JP-A-60-186506, a cellulose ester or the like is used as a protective colloid, a water content is adjusted to 10 to 40% by weight, and then a crosslinking agent having two or more functional groups is used. It is described that they can be crosslinked. Further, JP-A-63-61005 describes surface-crosslinking a hydrophilic porous polymer having a water content of 40% by weight or less with a crosslinking agent.
【０００５】そして、これらの方法により表面架橋を効
果的に行なうためには、実際上、ポリマーの含水率を１
０〜３０重量％程度にする必要がある。すなわち、ポリ
マーの含水率が高いと（例えば４０重量％以上、特に４
５重量％以上であると）、通常の架橋剤を用いた場合に
は、架橋反応がポリマー粒子の内部にまで進み（内部架
橋となり）、ポリマー粒子表面の架橋密度を上げること
ができない。従って、表面架橋を効果的に行なうために
は、ポリマーの含水率をできるだけ下げておく必要があ
る。In order to effectively carry out surface cross-linking by these methods, the water content of the polymer is practically set to 1
It is necessary to make it about 0 to 30% by weight. That is, when the water content of the polymer is high (for example, 40% by weight or more, especially 4% by weight).
When it is 5% by weight or more), when a normal crosslinking agent is used, the crosslinking reaction proceeds to the inside of the polymer particles (internal crosslinking) and the crosslinking density on the surface of the polymer particles cannot be increased. Therefore, in order to effectively carry out surface cross-linking, it is necessary to reduce the water content of the polymer as much as possible.
【０００６】しかしながら、吸水性ポリマーの重合は、
通常、モノマー濃度が４５重量％以下、すなわち、重合
終了時のポリマーの含水率が、５５重量％以上となる範
囲で実施される。従って、上記のようにして表面架橋を
行なう際には、重合終了後、共沸脱水等の何らかの方法
により特定量の水分を除去するか、或いは一旦乾燥させ
たポリマーに再び水を添加して水分量を調節するなどの
工程が必要であり、これに多大な時間と労力を要すると
いう問題があった。However, the polymerization of the water-absorbing polymer is
Usually, the monomer concentration is 45% by weight or less, that is, the water content of the polymer at the end of the polymerization is 55% by weight or more. Therefore, when the surface cross-linking is performed as described above, after the completion of the polymerization, a specific amount of water is removed by some method such as azeotropic dehydration, or water is added to the once dried polymer again to add water. There is a problem in that a process such as adjusting the amount is required, which requires a great deal of time and labor.
【０００７】本発明者らは、このような従来の問題を解
決すべく鋭意研究を進めた結果、４０重量％以上という
高い含水率を有する吸水性ポリマーを用い、これを特定
の水溶率を有する架橋剤で表面架橋することにより、脱
水操作を必要とすることなく、或いは少量の脱水を実施
するだけで、表面近傍のみを効果的に架橋し、飽和吸水
量とゲル強度が共に優れ、かつ吸水速度が高い吸水性ポ
リマーを製造することができることを見出し、この知見
に基づいて本発明を完成するに到った。The inventors of the present invention have conducted extensive studies to solve such conventional problems, and as a result, have used a water-absorbing polymer having a high water content of 40% by weight or more and having a specific water-solubility. By surface cross-linking with a cross-linking agent, dehydration operation is not necessary or only a small amount of dehydration is performed, and only the vicinity of the surface is effectively cross-linked, and saturated water absorption and gel strength are both excellent, and water absorption It has been found that a water absorbing polymer having a high speed can be produced, and the present invention has been completed based on this finding.
【０００８】[0008]
【課題を解決するための手段】すなわち本発明は、ポリ
マー中の含水率が４０重量％以上の吸水性ポリマーを、
水溶率が２０〜８５重量％の架橋剤で表面架橋すること
を特徴とする表面架橋された吸水性ポリマーの製造方法
を提供するものである。That is, the present invention provides a water-absorbent polymer having a water content of 40% by weight or more,
Provided is a method for producing a surface-crosslinked water-absorbing polymer, which comprises surface-crosslinking with a crosslinking agent having a water solubility of 20 to 85% by weight.
【０００９】本発明で用いる吸水性ポリマーとしては、
その構成成分中に、カルボキシレートを含有するもので
あり、かつポリマー中の含水率が４０重量％以上のもの
であれば、重合体或いは共重合体のいずれでもよい。本
発明の方法は、水媒法，逆相懸濁重合法など、如何なる
方法で重合された吸水性ポリマーに対しても適用するこ
とができるが、特に逆相懸濁重合法で重合された吸水性
ポリマー、とりわけ多孔質の吸水性ポリマーについてそ
の効果、有用性が大きい。As the water-absorbent polymer used in the present invention,
Either a polymer or a copolymer may be used as long as it contains a carboxylate in its constituents and has a water content of 40% by weight or more in the polymer. The method of the present invention can be applied to a water-absorbing polymer polymerized by any method such as an aqueous medium method and a reverse-phase suspension polymerization method, but especially a water-absorbing polymer polymerized by the reverse-phase suspension polymerization method. The effect and usefulness of a water-soluble polymer, especially a porous water-absorbing polymer, are great.
【００１０】ここで油中水滴型の逆相懸濁重合法につい
て説明すると、逆相懸濁重合法は出発原料であるモノマ
ー水溶液を、分散剤或いは界面活性剤を加えた重合分散
媒中に懸濁し、重合開始剤を添加し、必要に応じて均一
（内部）架橋剤を添加して、逆相懸濁状態で重合を行な
うものである。より詳しく説明すると、逆相懸濁重合法
では、まず重合槽に予め重合分散媒と重合分散剤を入
れ、重合温度にまで加熱し、攪拌しておく。一方、こ
れとは別にモノマー水溶液（モノマー濃度２０〜５０重
量％程度に調製したもの）を調製し、これに重合開始剤
を加えたものを用意しておく。前記モノマー水溶液に
重合開始剤を加えたものを、前記重合槽に滴下し、重合
を行なう。この場合に、均一架橋剤として水溶性架橋剤
（水溶率＝１００％）を予めモノマー水溶液に溶解させ
ておき、ポリマー全体をある程度架橋してもよい。ま
た、この代わりに、重合終了後に前記水溶性架橋剤を添
加し、ポリマー全体を架橋してもよい。The water-in-oil type reverse phase suspension polymerization method is described below. In the reverse phase suspension polymerization method, an aqueous monomer solution as a starting material is suspended in a polymerization dispersion medium containing a dispersant or a surfactant. It is turbid, a polymerization initiator is added, and if necessary, a uniform (internal) crosslinking agent is added, and polymerization is carried out in a reversed phase suspension state. More specifically, in the reverse phase suspension polymerization method, first, a polymerization dispersion medium and a polymerization dispersant are put in a polymerization tank in advance, heated to a polymerization temperature and stirred. On the other hand, separately from this, an aqueous monomer solution (prepared to have a monomer concentration of about 20 to 50% by weight) is prepared, and a solution prepared by adding a polymerization initiator thereto is prepared. What added the polymerization initiator to the said monomer aqueous solution is dripped at the said polymerization tank, and superposition | polymerization is performed. In this case, a water-soluble crosslinking agent (water solubility = 100%) as a uniform crosslinking agent may be previously dissolved in the monomer aqueous solution to crosslink the entire polymer to some extent. Alternatively, the water-soluble crosslinking agent may be added after the completion of polymerization to crosslink the entire polymer.
【００１１】このような逆相懸濁重合法においては、上
記の重合工程に引続き、本発明の特徴とする表面架橋
工程を実施するのが普通である。すなわち、この場合に
ついて簡単に説明すると、前記に続いて、次いで、
脱水することなく、或いは含水率が４０重量％以上まで
の範囲で脱水した後、水溶率の低い（２０〜８５重量
％）架橋剤を加え、１０分間〜１時間攪拌する。ポリ
マーを取り出して、乾燥させる。必要に応じて、得ら
れたポリマーを親水性微粒子状無機粉末と混合し、表面
処理を行なってもよい。In such a reverse phase suspension polymerization method, it is usual to carry out the surface cross-linking step which is the feature of the present invention, following the above-mentioned polymerization step. That is, to briefly explain this case, following the above, then,
Without dehydration or after dehydration in the range of water content up to 40% by weight or more, a crosslinking agent having a low water content (20 to 85% by weight) is added and stirred for 10 minutes to 1 hour. The polymer is removed and dried. If necessary, the obtained polymer may be mixed with hydrophilic fine particle-like inorganic powder for surface treatment.
【００１２】また、上記と同じ逆相懸濁重合法ではある
が、上記重合で用いるモノマー水溶液中に疎水性相を分
散させておき、特開昭６２−１０６９０２号公報に記載
されている方法と同様にして、逆相懸濁状態で重合を行
なってもよい。この方法によれば、多孔質の吸水性ポリ
マーを製造することができ、その後、上記〜の工程
を実施してもよい。すなわち、上記重合の際、モノマー
水溶液中に水溶性界面活性剤及び／又は水溶性高分子分
散剤を加え、これに疎水性有機化合物相を分散させて、
いわゆるＯ／Ｗエマルジョンを形成し、これを重合槽に
滴下して多孔質の吸水性ポリマーを製造し、以後、上記
〜の工程を実施してもよい。この多孔質の吸水性ポ
リマーは、吸水性，通気性，弾力性に富むため、本発明
の対象とする吸水性ポリマーとしては好ましいものであ
る。Further, although the same reverse phase suspension polymerization method as described above is used, the hydrophobic phase is dispersed in the aqueous monomer solution used in the above polymerization, and the method described in JP-A-62-106902 is used. Similarly, the polymerization may be carried out in a reversed phase suspension state. According to this method, a porous water-absorbing polymer can be produced, and then the above steps 1 to 3 may be carried out. That is, at the time of the above-mentioned polymerization, a water-soluble surfactant and / or a water-soluble polymer dispersant is added to the aqueous monomer solution, and the hydrophobic organic compound phase is dispersed therein,
A so-called O / W emulsion may be formed, and this may be dropped into a polymerization tank to produce a porous water-absorbing polymer, and thereafter, the above steps 1 to 3 may be carried out. This porous water-absorbent polymer is excellent in water absorbability, air permeability, and elasticity, and is therefore preferable as the water-absorbent polymer targeted by the present invention.
【００１３】このような逆相懸濁重合法における原料モ
ノマーとしては、α，β−不飽和カルボン酸、その誘導
体又はそれらの塩であり、これらは単独で用いてもよい
し、或いは２種以上を併用してもよい。また、必要に応
じて他の水溶性を有するオレフィン性モノマーを５０重
量％以下の割合で用いて共重合を行なうことも可能であ
る。また、デンプン，セルロースなどの成分を用いて、
これらの原料モノマーを、この成分にグラフト重合する
こともできる。具体的には例えば、アクリル酸、アクリ
ル酸塩（通常、ナトリウム塩，カリウム塩，アンモニウ
ム塩）、メタクリル酸、メタクリル酸塩（通常、ナトリ
ウム塩，カリウム塩，アンモニウム塩）、マレイン酸、
アクリルアミド、２−アクリル−２−メチルプロパンス
ルホン酸、２−ヒドロキシエチル（メタ）アクリレー
ト、アクリロニトリル等が挙げられる。通常、アクリル
酸或いはメタクリル酸１〜９０モル％と、アクリル酸塩
或いはメタクリル酸塩９９〜１０モル％との混合物が好
適に用いられる。重合の際には、通常、これらのモノマ
ーの２０〜７５重量％、好ましくは２５〜５０重量％の
水溶液を、原料として用いる。The raw material monomer in such a reverse phase suspension polymerization method is an α, β-unsaturated carboxylic acid, a derivative thereof or a salt thereof, which may be used alone or in combination of two or more kinds. You may use together. In addition, it is also possible to carry out the copolymerization by using other water-soluble olefinic monomers in a proportion of 50% by weight or less, if necessary. In addition, using ingredients such as starch and cellulose,
These raw material monomers can also be graft-polymerized to this component. Specifically, for example, acrylic acid, acrylic acid salt (usually sodium salt, potassium salt, ammonium salt), methacrylic acid, methacrylic acid salt (usually sodium salt, potassium salt, ammonium salt), maleic acid,
Examples thereof include acrylamide, 2-acryl-2-methylpropanesulfonic acid, 2-hydroxyethyl (meth) acrylate, acrylonitrile and the like. Usually, a mixture of 1 to 90 mol% of acrylic acid or methacrylic acid and 99 to 10 mol% of acrylic acid salt or methacrylic acid salt is preferably used. In the polymerization, an aqueous solution of 20 to 75% by weight, preferably 25 to 50% by weight of these monomers is usually used as a raw material.
【００１４】次に、重合分散媒としては、重合不活性
で、水を溶解しない性質を有するものが用いられ、具体
的にはｎ−ペンタン，ｎ−ヘキサン，ｎ−ペンタン等の
脂肪族飽和炭化水素、シクロヘキサン，シクロオクタ
ン，メチルシクロヘキサン，デカリン等の脂環式飽和炭
化水素、ベンゼン，トルエン，キシレン，エチルベンゼ
ン等の芳香族炭化水素、クロルベンゼン，ブロムベンゼ
ン等のハロゲン化芳香族炭化水素等が挙げられる。これ
ら重合分散媒の使用量は、特に限定はないが、モノマー
水溶液（多孔性ポリマー重合時はＯ／Ｗエマルジョン）
１００重量部に対して、１０〜５００重量部、好ましく
は３０〜４００重量部とするのが好ましい。これらの分
散媒は、モノマー滴下前に５０℃以上に加熱、攪拌して
用いられる。Next, as the polymerization dispersion medium, one which is polymerization-inert and has a property of not dissolving water is used. Specifically, saturated aliphatic carbonization such as n-pentane, n-hexane and n-pentane is used. Examples include hydrogen, alicyclic saturated hydrocarbons such as cyclohexane, cyclooctane, methylcyclohexane, and decalin, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and halogenated aromatic hydrocarbons such as chlorobenzene and brombenzene. To be The amount of the polymerization dispersion medium used is not particularly limited, but an aqueous monomer solution (O / W emulsion during polymerization of the porous polymer)
The amount is preferably 10 to 500 parts by weight, more preferably 30 to 400 parts by weight, based on 100 parts by weight. These dispersion media are used by heating and stirring at 50 ° C. or higher before dropping the monomer.
【００１５】また、重合分散剤としては、ソルビタン脂
肪酸エステル，ソルビタン脂肪酸エーテル，ソルビトー
ル脂肪酸エステル，ショ糖脂肪酸エステル等の非イオン
性界面活性剤、油溶性セルロースエステル、エチルセル
ロース等のセルロースエーテル、マレイン化ポリエチレ
ン，マレイン化α−オレフィン，ポリエチレングリコー
ル鎖を有するアクリル系共重合体等の高分子分散剤、シ
リカ，酸化アルミニウム，酸化チタン等に表面処理を施
して親油性を付与した無機微粉末等が挙げられる。これ
ら重合分散剤の使用量は、分散剤の種類により異なる
が、安定に重合が進行する範囲であれば特に制限はな
い。通常、重合分散媒の 0.01 〜２５重量％の範囲、好
ましくは 0.1〜１０重量％の範囲である。As the polymerization dispersant, nonionic surfactants such as sorbitan fatty acid ester, sorbitan fatty acid ether, sorbitol fatty acid ester and sucrose fatty acid ester, oil-soluble cellulose ester, ethyl ether and other cellulose ethers, and maleated polyethylene. , A maleic α-olefin, a polymer dispersant such as an acrylic copolymer having a polyethylene glycol chain, and an inorganic fine powder obtained by surface-treating silica, aluminum oxide, titanium oxide or the like to impart lipophilicity. . The amount of the polymerization dispersant used varies depending on the type of the dispersant, but is not particularly limited as long as the polymerization proceeds stably. Usually, it is in the range of 0.01 to 25% by weight, preferably 0.1 to 10% by weight of the polymerization dispersion medium.
【００１６】さらに、重合開始剤としては、特に制限は
なく、各種アルキルパーエステル、過酸化水素、過硫酸
塩、過塩素酸塩、アゾ化合物等が挙げられ、これらの１
種又は２種以上を用いることができるが、とりわけ過酸
化水素、過硫酸アンモニウム，過硫酸カリウムなどの過
硫酸塩、２−２’−アゾビス（２−アミジノプロパン）
ジヒドロクロリド等の水溶性重合開始剤が好ましい。重
合開始剤の使用量は、通常、原料モノマーに対して、
0.001〜１０重量％、好ましくは、0.01〜５重量％であ
る。Further, the polymerization initiator is not particularly limited, and various alkyl peresters, hydrogen peroxide, persulfates, perchlorates, azo compounds and the like can be mentioned.
One or two or more species can be used, but especially persulfates such as hydrogen peroxide, ammonium persulfate and potassium persulfate, 2-2′-azobis (2-amidinopropane)
Water-soluble polymerization initiators such as dihydrochloride are preferred. The amount of the polymerization initiator used is usually relative to the raw material monomer,
The amount is 0.001 to 10% by weight, preferably 0.01 to 5% by weight.
【００１７】なお、ポリマーの全体（内部）を架橋する
ための均一架橋剤として、重合前、重合時、或いは重合
後の任意のときに、公知の任意の水溶性架橋剤（水溶率
＝１００％）を使用することができる。具体的には例え
ば、ポリグリシジル化合物〔（ポリ）エチレングリコー
ルジグリシジルエーテル，（ポリ）プロピレングリコー
ルジグリシジルエーテル，（ポリ）グリセリンジグリシ
ジルエーテルなど〕、ポリアリル化合物（ジアリルフタ
レートなど）、ポリビニル化合物（ジビニルベンゼンな
ど）、ハロエポキシ化合物（エピクロルヒドリンな
ど）、ポリアルデヒド（グルタルアルデヒドなど）、ポ
リアミン、ポリオール、多価金属塩等が挙げられる。こ
のような均一架橋剤の使用量は、原料モノマーに対し
て、通常、0.001 〜１０重量％、好ましくは 0.01 〜５
重量％である。As a uniform cross-linking agent for cross-linking the whole (inside) of the polymer, any known water-soluble cross-linking agent (water-soluble rate = 100%) can be used before, during or after the polymerization. ) Can be used. Specifically, for example, polyglycidyl compounds [(poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether], polyallyl compounds (diallyl phthalate, etc.), polyvinyl compounds (divinyl) Examples thereof include benzene), haloepoxy compounds (such as epichlorohydrin), polyaldehydes (such as glutaraldehyde), polyamines, polyols, and polyvalent metal salts. The amount of such a uniform crosslinking agent used is usually 0.001 to 10% by weight, preferably 0.01 to 5% by weight based on the raw material monomers.
% By weight.
【００１８】これらの成分を添加して、上記した如き逆
相懸濁重合法により重合を行なって、本発明の対象とす
る吸水性ポリマーを製造することができる。なお、多孔
質の吸水性ポリマーを製造する場合には、多孔質のもの
とするために、上記の如く、さらに水溶性界面活性剤及
び／又は水溶性高分子分散剤と、疎水性有機化合物とを
用いる。すなわち、上記重合の際、モノマー水溶液中に
水溶性界面活性剤及び／又は水溶性高分子分散剤を加
え、これに疎水性有機化合物相を分散させて、いわゆる
Ｏ／Ｗエマルジョンを形成し、これを重合槽に滴下して
多孔質の吸水性ポリマーを製造することができる。By adding these components and carrying out polymerization by the reverse phase suspension polymerization method as described above, the water-absorbent polymer which is the object of the present invention can be produced. When a porous water-absorbing polymer is produced, in order to make it porous, a water-soluble surfactant and / or a water-soluble polymer dispersant and a hydrophobic organic compound are added as described above. To use. That is, at the time of the above polymerization, a water-soluble surfactant and / or a water-soluble polymer dispersant is added to an aqueous monomer solution, and a hydrophobic organic compound phase is dispersed therein to form a so-called O / W emulsion. Can be dropped into the polymerization tank to produce a porous water-absorbing polymer.
【００１９】ここで水溶性界面活性剤としては、水溶性
であれば特に限定はなく、任意の界面活性剤が用いられ
る。それらの中でも特に、ラウリル硫酸ナトリウム，ポ
リオキシエチレンラウリル硫酸ナトリウムなどの長鎖ア
ルキル硫酸塩類や、モノステアリン酸ポリオキシエチレ
ングリセリンエステルなどの脂肪酸エステル類が好まし
い。また、水溶性高分子分散剤としては例えば、部分け
ん化ポリビニルアルコールや変性ポリビニルアルコール
等が挙げられる。なお、けん化度は６０〜９５モル％程
度のものが用いられ、重合度は１００〜３０００程度で
ある。これらの添加量は、通常、それぞれモノマー水溶
液に対して、 0.001〜２０重量％、好ましくは 0.01 〜
１０重量％である。The water-soluble surfactant is not particularly limited as long as it is water-soluble, and any surfactant can be used. Among these, long-chain alkyl sulfates such as sodium lauryl sulfate and sodium polyoxyethylene lauryl sulfate, and fatty acid esters such as polyoxyethylene glycerin monostearate are particularly preferable. Examples of the water-soluble polymer dispersant include partially saponified polyvinyl alcohol and modified polyvinyl alcohol. The saponification degree is about 60 to 95 mol%, and the degree of polymerization is about 100 to 3000. The addition amount of these is usually 0.001 to 20% by weight, preferably 0.01 to 20% by weight based on the aqueous monomer solution.
It is 10% by weight.
【００２０】また、疎水性有機化合物としては、前記し
た重合分散媒と同じものを用いるのが普通である。例え
ば、ｎ−ペンタン，ｎ−ヘキサン，ｎ−ペンタン等の脂
肪族飽和炭化水素、シクロヘキサン，シクロオクタン，
メチルシクロヘキサン，デカリン等の脂環式飽和炭化水
素、ベンゼン，トルエン，キシレン，エチルベンゼン等
の芳香族炭化水素、クロルベンゼン，ブロムベンゼン等
のハロゲン化芳香族炭化水素、脂肪族アルコール、脂肪
族ケトン類、脂肪族エステル類等が挙げられる。これら
疎水性有機化合物の添加量は、モノマー水溶液１００重
量部に対して、１〜５００重量部、好ましくは２０〜３
００重量部の範囲である。As the hydrophobic organic compound, it is usual to use the same one as the above-mentioned polymerization dispersion medium. For example, saturated aliphatic hydrocarbons such as n-pentane, n-hexane and n-pentane, cyclohexane, cyclooctane,
Alicyclic saturated hydrocarbons such as methylcyclohexane and decalin, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, halogenated aromatic hydrocarbons such as chlorobenzene and bromobenzene, aliphatic alcohols and aliphatic ketones, Examples thereof include aliphatic esters. The amount of the hydrophobic organic compound added is 1 to 500 parts by weight, preferably 20 to 3 parts by weight, based on 100 parts by weight of the aqueous monomer solution.
It is in the range of 00 parts by weight.
【００２１】以上の如くして、逆相懸濁重合法により重
合を行なって、吸水性ポリマー、好ましくは多孔質の吸
水性ポリマーを製造することができる。なお、重合条件
は特に制限はなく、常法により行なえばよい。通常、重
合温度は５０℃以上、好ましくは６０〜９０℃である。
また、重合時間は通常、３０分以上が好ましい。As described above, the water-absorbing polymer, preferably a porous water-absorbing polymer, can be produced by carrying out the polymerization by the reverse phase suspension polymerization method. There are no particular restrictions on the polymerization conditions, and any conventional method may be used. Usually, the polymerization temperature is 50 ° C or higher, preferably 60 to 90 ° C.
The polymerization time is usually preferably 30 minutes or longer.
【００２２】このようにして本発明の対象とする吸水性
ポリマーが得られる。これら吸水性ポリマーとして具体
的には例えば、アクリル酸重合体，アクリル酸塩重合
体，メタクリル酸重合体，メタクリル酸塩重合体，イソ
ブチレン−マレイン酸共重合体，酢酸ビニル−アクリル
酸エステル共重合体けん化物，アクリル酸−アクリルア
ミド共重合体，デンプン−アクリル酸グラフト共重合体
中和物，デンプン−アクリロニトリルグラフト共重合体
加水分解物等が挙げられる。In this way, the water-absorbent polymer targeted by the present invention is obtained. Specific examples of these water-absorbent polymers include acrylic acid polymers, acrylate polymers, methacrylic acid polymers, methacrylate polymers, isobutylene-maleic acid copolymers, vinyl acetate-acrylic acid ester copolymers. Examples thereof include saponified products, acrylic acid-acrylamide copolymers, starch-acrylic acid graft copolymer neutralized products, starch-acrylonitrile graft copolymer hydrolysates, and the like.
【００２３】これらの吸水性ポリマーは、前記したよう
に、吸水ゲルの強度を上げるためにポリマー全体の架橋
度を高めたものであると、飽和吸水量が低下したものと
なっている。逆に飽和吸水量を上げるために架橋度を下
げたものであると、ゲルの強度が低下するだけでなく、
表面の濡れ性が悪くなり、吸収速度も低下したものとな
っている。そこで、飽和吸水量を低下させることなく、
吸水ゲルの強度を向上させ、かつ吸水速度も向上させる
ために、通常、吸水性ポリマーの表面近傍のみを架橋し
ているが、吸水性ポリマーの表面近傍のみを、従来法に
より効果的に架橋するためには、実際上ポリマー中の含
水率が１０〜３０重量％程度である必要がある。ところ
が、重合終了時の吸水性ポリマーの含水率は、通常、５
５重量％以上と高い水準にある。従って、従来の方法で
は、吸水性ポリマーの表面近傍のみを効果的に架橋する
ために、実際上、ポリマー中の含水率が１０〜３０重量
％程度となるように脱水する必要があり、このような範
囲に脱水した後、表面架橋を行なっているが、この脱水
操作に多大な時間と労力を必要としていた。そこで本発
明では、水溶率が２０〜８０重量％の架橋剤を用いて表
面架橋を行なうことにより、含水率が４０重量％以上と
高いポリマーについても、脱水操作を必要とすることな
く、或いは少量の脱水を実施するだけで、飽和吸水量を
低下させることなく、吸水ゲルの強度を向上させ、かつ
吸水速度も向上させることができたものである。As described above, when these water-absorbing polymers are those in which the degree of crosslinking of the entire polymer is increased in order to increase the strength of the water-absorbing gel, the saturated water absorption amount is lowered. Conversely, if the degree of cross-linking is lowered in order to increase the saturated water absorption, not only will the gel strength decrease, but
The wettability of the surface is poor and the absorption rate is also low. Therefore, without reducing the saturated water absorption,
In order to improve the strength of the water-absorbing gel and also improve the water-absorption rate, usually, only the surface vicinity of the water-absorbing polymer is cross-linked, but only the surface vicinity of the water-absorbing polymer is effectively cross-linked by the conventional method. In order to do so, it is necessary that the water content in the polymer is practically about 10 to 30% by weight. However, the water content of the water-absorbent polymer at the end of the polymerization is usually 5
It is at a high level of over 5% by weight. Therefore, in the conventional method, in order to effectively crosslink only the vicinity of the surface of the water-absorbing polymer, it is necessary to dehydrate the polymer so that the water content in the polymer is about 10 to 30% by weight. Surface dehydration was carried out after dehydration to a certain range, but this dehydration operation required a great deal of time and labor. Therefore, in the present invention, surface cross-linking is performed using a cross-linking agent having a water content of 20 to 80% by weight, so that even a polymer having a high water content of 40% by weight or more does not require dehydration operation or a small amount thereof. It was possible to improve the strength of the water-absorbent gel and also the water-absorption rate without lowering the saturated water absorption amount simply by performing the dehydration of the above.
【００２４】すなわち本発明は、表面架橋された吸水性
ポリマーを製造するにあたり、ポリマー中の含水率が４
０重量％以上の吸水性ポリマーを、水溶率が２０〜８５
重量％の架橋剤で表面架橋することを特徴とするもので
ある。That is, according to the present invention, in producing a surface-crosslinked water-absorbing polymer, the water content in the polymer is 4%.
A water-absorbing polymer of 0% by weight or more having a water solubility of 20 to 85
It is characterized by being surface-crosslinked with a cross-linking agent in a weight percentage.
【００２５】ここで「ポリマー中の含水率が４０重量％
以上の吸水性ポリマー」とは、前記の如き方法により製
造された吸水性ポリマーについて、ポリマー中の含水率
がそれほど高くないものについては脱水することなくそ
のまま、或いはポリマー中の含水率がある程度高いもの
については含水率が４０重量％以上までの範囲となるよ
うに少量の脱水を実施したものを意味する。なお、含水
率（重量％）とは、吸水ゲル（含水ゲル）中の水分重量
を吸水ゲル（含水ゲル）重量で除した値を百分率で表し
たものである。通常、４０〜７５重量％、好ましくは４
５〜６０重量％の含水率を有する吸水性ポリマーについ
て、本発明が適用される。脱水する場合の脱水操作は、
常法により行なえばよい。Here, "the water content in the polymer is 40% by weight.
The above-mentioned water-absorbing polymer is a water-absorbing polymer produced by the method as described above, as long as the water content in the polymer is not so high, as it is without dehydration, or the water content in the polymer is high to some extent. Means that a small amount of water was dehydrated so that the water content was in the range of 40% by weight or more. The water content (% by weight) is a value obtained by dividing the weight of water in the water-absorbing gel (water-containing gel) by the weight of the water-absorbing gel (water-containing gel) in percentage. Usually 40 to 75% by weight, preferably 4
The invention applies to water-absorbing polymers having a water content of 5 to 60% by weight. For dehydration,
It may be carried out by a conventional method.
【００２６】本発明において、表面架橋に用いる架橋剤
（表面架橋剤）としては、カルボキシル基などポリマー
中に存在する官能基と反応する官能基を少なくとも２以
上保有し、かつ、水溶率が２０〜８５重量％、好ましく
は２５〜８０重量％のものである。ここで水溶率（重量
％）とは、室温（２５℃）において、水９０重量部に対
して架橋剤１０重量部を溶かした場合の溶解率をいう。In the present invention, the cross-linking agent (surface cross-linking agent) used for surface cross-linking has at least two functional groups that react with functional groups present in the polymer such as a carboxyl group, and has a water solubility of 20 to 20. 85% by weight, preferably 25-80% by weight. Here, the water solubility (% by weight) means the solubility when 10 parts by weight of the crosslinking agent is dissolved in 90 parts by weight of water at room temperature (25 ° C.).
【００２７】このような表面架橋剤としては、前記した
均一架橋剤（水溶率が１００％のもの）と同様の化合
物、例えばポリグリシジル化合物，ハロエポキシ化合
物，アルデヒド化合物，イソシアネート化合物等であっ
て、水溶率が２０〜８５重量％のものが用いられる。特
に水溶率が２０〜８５重量％のポリグリシジル化合物が
好ましい。このような表面架橋剤として具体的には例え
ば、ナガセ化成社製のプロピレングリコールジグリシジ
ルエーテル（商品名：デナコールＥＸ−９１１，水溶率
＝７５重量％）、同じくナガセ化成社製のネオペンチル
グリコールジグリシジルエーテル（商品名：デナコール
ＥＸ−２１１，水溶率＝２６重量％）等が挙げられる。
表面架橋剤の添加量は、生成ポリマーに対して、通常、
0.001 〜１０重量％である。ここで表面架橋剤の添加量
が0.001 重量％未満であると添加効果が発現せず、一
方、表面架橋剤の添加量が１０重量％を超えると全体に
架橋度が高くなり、飽和吸水量が低下してしまうため、
いずれも好ましくない。なお、この表面架橋は、常法と
同様の条件により行なえばよいが、通常、架橋時間は、
１０分間〜１時間である。As such a surface cross-linking agent, the same compounds as the above-mentioned uniform cross-linking agent (having a water-soluble rate of 100%), for example, polyglycidyl compounds, haloepoxy compounds, aldehyde compounds, isocyanate compounds, etc. A rate of 20 to 85% by weight is used. A polyglycidyl compound having a water solubility of 20 to 85% by weight is particularly preferable. Specific examples of such a surface cross-linking agent include propylene glycol diglycidyl ether (trade name: Denacol EX-911, water solubility = 75% by weight) manufactured by Nagase Kasei Co., Ltd., and also neopentyl glycol diene manufactured by Nagase Kasei Co., Ltd. Glycidyl ether (trade name: Denacol EX-211, water solubility = 26% by weight) and the like can be mentioned.
The amount of the surface cross-linking agent added is usually,
It is 0.001 to 10% by weight. If the addition amount of the surface cross-linking agent is less than 0.001% by weight, the addition effect will not be exhibited. On the other hand, if the addition amount of the surface cross-linking agent exceeds 10% by weight, the degree of cross-linking will be high and the saturated water absorption will be high. Because it will decrease
Neither is preferable. The surface cross-linking may be carried out under the same conditions as in the conventional method, but usually, the cross-linking time is
10 minutes to 1 hour.
【００２８】このようにして、目的とする、表面近傍の
みが架橋された吸水性ポリマー（表面架橋された吸水性
ポリマー）を製造することができる。得られた、表面架
橋された吸水性ポリマーは、前記したように、乾燥した
後、そのまま用いてもよいし、必要に応じて親水性微粒
子状無機粉末と混合して、より親水性を改良するための
表面処理を行なってもよい。ここで親水性微粒子状無機
粉末としては特に制限はないが、なかでも親水性微粒子
状シリカが最も好ましい。親水性微粒子状無機粉末の添
加量は、処理するポリマーに対して、通常 0.01 〜１０
重量％である。なお、その一次粒子径は通常、５ｎｍ〜
１０μｍ程度である。In this way, the desired water-absorbing polymer in which only the vicinity of the surface is crosslinked (surface-crosslinked water-absorbing polymer) can be produced. The obtained surface-crosslinked water-absorbing polymer may be used as it is after being dried, as described above, or may be mixed with hydrophilic fine particle-like inorganic powder to improve hydrophilicity, if necessary. You may perform surface treatment for. Here, the hydrophilic fine particle inorganic powder is not particularly limited, but hydrophilic fine particle silica is most preferable. The addition amount of the hydrophilic fine particle inorganic powder is usually 0.01 to 10 with respect to the polymer to be treated.
% By weight. The primary particle diameter is usually 5 nm to
It is about 10 μm.
【００２９】[0029]
【実施例】次に本発明を実施例により詳しく説明する。 実施例１ 攪拌機，還流冷却管，モノマー滴下口及び窒素ガス導入
管を備えた２リットル容の４つ口フラスコに、シクロヘ
キサン７２０ｇとエチルセルロース３．２ｇ（ハーキュ
レス社製，商品名：Ｎ−５０）を加えて攪拌し、窒素ガ
スを吹き込んで溶存酸素を追い出し、７０℃まで昇温し
た。EXAMPLES The present invention will now be described in more detail with reference to examples. Example 1 A 2-liter four-necked flask equipped with a stirrer, a reflux condenser, a monomer dropping port, and a nitrogen gas inlet pipe was charged with 720 g of cyclohexane and 3.2 g of ethyl cellulose (Hercules, trade name: N-50). In addition, the mixture was stirred, nitrogen gas was blown into it to expel dissolved oxygen, and the temperature was raised to 70 ° C.
【００３０】一方、別のフラスコ中で、水酸化ナトリウ
ム８６ｇを水３００ｇに溶解し、これにアクリル酸２０
０ｇを加えて中和し、調製した水溶液に、過硫酸アンモ
ニウム 0.79 ｇ、部分ケン化ポリビニルアルコール（日
本合成化学社製、商品名：ＧＨ−１７）1.０ｇ及びシク
ロヘキサン３００ｇを加えて攪拌し、窒素ガスを吹き込
んで溶存酸素を追い出し、Ｏ／Ｗエマルジョンを調製し
た。次に、前記４つ口フラスコを５００ｒｐｍの速度で
攪拌しながら、前記Ｏ／Ｗエマルジョンを３時間かけて
滴下した。次いで、均一架橋剤（内部架橋剤）として、
エチレングリコールジグリシジルエーテル（ナガセ化成
社製、商品名：デナコールＥＸ−８１０、水溶率＝１０
０％）２００ｍｇを加え、さらに１時間攪拌した。On the other hand, in another flask, 86 g of sodium hydroxide was dissolved in 300 g of water, and 20 g of acrylic acid was added thereto.
To the prepared aqueous solution was added 0 g of neutralization, and 0.79 g of ammonium persulfate, 1.0 g of partially saponified polyvinyl alcohol (Nippon Gosei Kagaku KK, trade name: GH-17) and 300 g of cyclohexane were added and stirred, and nitrogen was added. A gas was blown in to expel dissolved oxygen to prepare an O / W emulsion. Next, the O / W emulsion was added dropwise over 3 hours while stirring the 4-neck flask at a speed of 500 rpm. Then, as a uniform crosslinking agent (internal crosslinking agent),
Ethylene glycol diglycidyl ether (manufactured by Nagase Chemicals Co., Ltd., trade name: Denacol EX-810, water solubility = 10)
(0%) 200 mg was added, and the mixture was further stirred for 1 hour.
【００３１】次に、共沸脱水によって１６５ｇの水を抜
き出した後（生成ポリマーの含水率＝４５重量％）、表
面架橋剤としてプロピレングリコールジグリシジルエー
テル（ナガセ化成社製、商品名：デナコールＥＸ−９１
１、水溶率＝７５％）２００ｍｇを添加し、３０分間攪
拌した。７０℃から室温まで冷却後、減圧下にて１３０
℃で乾燥させ、球状の吸水性樹脂を得た。得られた樹脂
に対して、１．５重量％の親水性微粒子状シリカ（徳山
ソーダ社製、商品名：トクシールＮ）を混合して表面処
理した後、以下の方法により吸水性能（ゲル強度，飽和
吸水量及び初期吸水速度）を測定した。結果を第１表に
示す。Next, after 165 g of water was extracted by azeotropic dehydration (water content of the produced polymer = 45% by weight), propylene glycol diglycidyl ether (manufactured by Nagase Kasei Co., trade name: Denacol EX-) was used as a surface crosslinking agent. 91
200% of water solubility = 75%) was added and stirred for 30 minutes. After cooling from 70 ℃ to room temperature, 130 under reduced pressure
It was dried at ° C to obtain a spherical water absorbent resin. 1.5% by weight of hydrophilic fine particle silica (manufactured by Tokuyama Soda Co., Ltd., trade name: Tokuseal N) was mixed with the obtained resin for surface treatment, and then the water absorption performance (gel strength, gel strength, The saturated water absorption amount and the initial water absorption rate) were measured. The results are shown in Table 1.
【００３２】なお、上記の吸水性能は、次のようにして
測定した。 〔ゲル強度〕５０ミリリットル容のビーカーに、前記樹
脂（２ｇ）を入れ、これに純水（４０ｇ）を一気に加
え、２０倍ゲルを作成する。これを１時間静置後、２つ
に分割し、それぞれを内径６２ｍｍの円筒容器に入れ、
上から直径６０ｍｍの円板でゆっくり圧縮する。ゲルが
荷重に耐えきれず、円板と円筒容器内壁の隙間からはみ
出てくるまで圧縮し、そのまま１０分間静置した後、ゲ
ルの応力を測定する。２回の測定結果の平均値をゲル強
度とした。The above water absorption performance was measured as follows. [Gel Strength] The resin (2 g) was placed in a beaker having a volume of 50 ml, and pure water (40 g) was added all at once to prepare a 20 times gel. After leaving this for 1 hour, divide it into two, put each into a cylindrical container with an inner diameter of 62 mm,
Slowly compress with a 60 mm diameter disc from above. The gel is compressed until it cannot withstand the load and protrudes from the gap between the disc and the inner wall of the cylindrical container, and allowed to stand for 10 minutes, and then the stress of the gel is measured. The average value of the two measurement results was taken as the gel strength.
【００３３】〔飽和吸水量〕６０ｍｍ×８０ｍｍの不織
布製の袋に前記樹脂（ 0.3ｇ）を入れ、これを 0.9％の
生理食塩水中に３０分間浸漬する。その後、水中から取
り出したサンプルを、３０度に傾けた金網状で１分間水
切りした後、その重量を測定する。ブランクの重量を差
し引き、樹脂１ｇ当りに換算したものを飽和吸水量とし
た。[Saturated Water Absorption] The resin (0.3 g) was placed in a non-woven bag of 60 mm × 80 mm and immersed in 0.9% physiological saline for 30 minutes. After that, the sample taken out from the water is drained for 1 minute in a wire mesh shape inclined at 30 degrees, and then the weight is measured. The saturated water absorption was calculated by subtracting the weight of the blank and converting it per 1 g of the resin.
【００３４】〔初期吸水速度〕直径２０ｍｍの円筒容器
（底部は不織布と金網で作製されている）に前記樹脂0.
1ｇを均等に入れ、吸水測定機（協和精工社製）を用い
て、前記樹脂が人工尿を吸収し始めてから１分間の吸収
量（ｍｌ）を測定し、樹脂１ｇ当りに換算した値（ｍｌ
／ｇ）を初期吸収速度とした。なお、人工尿の組成を以
下に示す。[Initial Water Absorption Rate] The above resin was added to a cylindrical container having a diameter of 20 mm (the bottom portion was made of non-woven fabric and wire mesh).
1 g was evenly placed, and the amount of absorption (ml) for 1 minute after the resin started to absorb artificial urine was measured using a water absorption measuring device (manufactured by Kyowa Seiko Co., Ltd.), and the value was converted per 1 g of resin (ml
/ G) was taken as the initial absorption rate. The composition of artificial urine is shown below.
【００３５】・人工尿の組成 H2O 97.09 wt% H2NCONH2 1.94 wt% NaCl 0.80 wt% MgSO4 ・H2O 0.11 wt% CaCl2 0.06 wt%Composition of artificial urine H 2 O 97.09 wt% H 2 NCONH 2 1.94 wt% NaCl 0.80 wt% MgSO 4・ H 2 O 0.11 wt% CaCl 2 0.06 wt%
【００３６】実施例２ 表面架橋剤として、プロピレングリコールジグリシジル
エーテルの代わりに、ジプロピレングリコールジグリシ
ジルエーテル（ナガセ化成社製、商品名：デナコールＥ
Ｘ−９４１、水溶率＝８０％）２００ｍｇを加えたこと
以外は、実施例１と同様の方法で重合を行ない、球状の
吸水性樹脂を得、親水性微粒子状シリカを混合して表面
処理した。吸水性能の測定結果を第１表に示す。Example 2 As a surface cross-linking agent, instead of propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether (manufactured by Nagase Kasei Co., Ltd., trade name: Denacol E)
X-941, water solubility = 80%) Polymerization was carried out in the same manner as in Example 1 except that 200 mg was added to obtain a spherical water-absorbent resin, and hydrophilic fine particle silica was mixed and surface-treated. . Table 1 shows the measurement results of the water absorption performance.
【００３７】実施例３ 共沸脱水を実施せず（生成ポリマーの含水率＝６０重量
％）、かつ表面架橋剤として、プロピレングリコールジ
グリシジルエーテルの代わりに、ネオペンチルグリコー
ルジグリシジルエーテル（ナガセ化成社製、商品名：デ
ナコールＥＸ−２１１、水溶率＝２６％）２００ｍｇを
加えたこと以外は、実施例１と同様にして重合を行な
い、球状の吸水性樹脂を得、親水性微粒子状シリカを混
合して表面処理した。吸水性能の測定結果を第１表に示
す。Example 3 Without azeotropic dehydration (water content of produced polymer = 60% by weight), and as a surface cross-linking agent, instead of propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether (Nagase Kasei Co., Ltd.) was used. Production, trade name: Denacol EX-211, water solubility = 26%) Polymerization was performed in the same manner as in Example 1 except that 200 mg was added to obtain a spherical water-absorbent resin, and hydrophilic fine particle silica was mixed. And surface-treated. Table 1 shows the measurement results of the water absorption performance.
【００３８】比較例１ 共沸脱水により１６５ｇの水を抜き出して、生成ポリマ
ーの含水率を４５重量％とし、かつ表面架橋剤を添加せ
ずにそのまま乾燥させたこと以外は、実施例１と同様の
方法で重合を行ない、球状の吸水性樹脂を得、親水性微
粒子状シリカを混合して表面処理した。吸水性能の測定
結果を第１表に示す。Comparative Example 1 Same as Example 1 except that 165 g of water was extracted by azeotropic dehydration to bring the water content of the resulting polymer to 45% by weight and to dry it as it was without adding a surface crosslinking agent. Polymerization was carried out by the above method to obtain a spherical water-absorbent resin, and hydrophilic fine particle silica was mixed and surface-treated. Table 1 shows the measurement results of the water absorption performance.
【００３９】比較例２ 共沸脱水により、１６５ｇの水を抜き出して生成ポリマ
ーの含水率を４５重量％とし、かつ表面架橋剤としての
プロピレングリコールジグリシジルエーテルの代わり
に、エチレングリコールジグリシジルエーテル（ナガセ
化成社製、商品名：デナコールＥＸ−８１１、水溶率＝
９５％）２００ｍｇを加えたこと以外は、実施例１と同
様の方法で重合を行ない、球状の吸水性樹脂を得、親水
性微粒子状シリカを混合して表面処理した。吸水性能の
測定結果を第１表に示す。Comparative Example 2 165 g of water was extracted by azeotropic dehydration to make the water content of the produced polymer 45% by weight, and ethylene glycol diglycidyl ether (Nagase) was used instead of propylene glycol diglycidyl ether as a surface cross-linking agent. Kasei Co., Ltd., trade name: Denacol EX-811, water solubility =
Polymerization was performed in the same manner as in Example 1 except that 200 mg of 95%) was added to obtain a spherical water-absorbent resin, and hydrophilic fine particle silica was mixed for surface treatment. Table 1 shows the measurement results of the water absorption performance.
【００４０】[0040]
【表１】 [Table 1]
【００４１】第１表の結果から、比較例１のように均一
架橋剤（内部架橋剤）のみを用いた場合にはゲル強度が
不充分となることが分かる。また、比較例２のように、
水溶率の高い（９５重量％）表面架橋剤を用いた場合に
は、比較例１に比し、ゲル強度の高い樹脂が得られるも
のの、飽和吸水量が非常に低くなることが分かる。From the results shown in Table 1, it is understood that the gel strength becomes insufficient when only the uniform crosslinking agent (internal crosslinking agent) is used as in Comparative Example 1. In addition, as in Comparative Example 2,
It can be seen that when a surface cross-linking agent having a high water solubility (95% by weight) is used, a resin having a high gel strength can be obtained as compared with Comparative Example 1, but the saturated water absorption becomes very low.
【００４２】[0042]
【発明の効果】本発明の方法によれば、含水率が４０重
量％以上という高い含水率を有する吸水性ポリマーを用
い、これを特定の水溶率を有する架橋剤で表面架橋して
いるため、脱水操作を必要としないか、或いは少量の脱
水を実施するだけでよい。しかも本発明の方法によれ
ば、特定の水溶率を有する架橋剤で表面架橋しているた
め、ポリマーの表面近傍のみが効果的に架橋され、飽和
吸水量とゲル強度が共に優れ、かつ、吸水速度が高い吸
水性ポリマーを製造することができる。従って、本発明
は、衛生材料，農業・園芸材料等の分野で極めて有効に
利用することができる。According to the method of the present invention, since a water-absorbing polymer having a high water content of 40% by weight or more is used and surface-crosslinked with a crosslinking agent having a specific water content, No dehydration operation is required or only a small amount of dehydration needs to be performed. Moreover, according to the method of the present invention, since the surface is cross-linked with a cross-linking agent having a specific water solubility, only the vicinity of the surface of the polymer is effectively cross-linked, and the saturated water absorption amount and the gel strength are both excellent, and the water absorption It is possible to produce a water absorbing polymer having a high rate. Therefore, the present invention can be used very effectively in the fields of sanitary materials, agricultural / horticultural materials, and the like.
フロントページの続き (72)発明者 福本 祐二 山口県徳山市新宮町１番１号 出光石油化 学株式会社内Front Page Continuation (72) Inventor Yuji Fukumoto 1-1, Shingucho, Tokuyama City, Yamaguchi Prefecture Idemitsu Petrochemical Co., Ltd.
Claims (4)
吸水性ポリマーを、水溶率が２０〜８５重量％の架橋剤
で表面架橋することを特徴とする表面架橋された吸水性
ポリマーの製造方法。1. Production of a surface-crosslinked water-absorbent polymer, characterized in that a water-absorbent polymer having a water content of 40% by weight or more is surface-crosslinked with a crosslinking agent having a water-content of 20 to 85% by weight. Method.
である請求項１記載の製造方法。2. The water content of the polymer is 45 to 75% by weight.
The manufacturing method according to claim 1, wherein
求項１記載の製造方法。3. The method according to claim 1, wherein the crosslinking agent is a polyglycidyl compound.
請求項１記載の製造方法。4. The production method according to claim 1, wherein the water-absorbent polymer is a porous polymer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19267493A JPH0726026A (en) | 1993-07-08 | 1993-07-08 | Production of water-absorbing polymer with surface cross-linked |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19267493A JPH0726026A (en) | 1993-07-08 | 1993-07-08 | Production of water-absorbing polymer with surface cross-linked |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0726026A true JPH0726026A (en) | 1995-01-27 |
Family
ID=16295162
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19267493A Withdrawn JPH0726026A (en) | 1993-07-08 | 1993-07-08 | Production of water-absorbing polymer with surface cross-linked |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0726026A (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2744456A1 (en) * | 1996-02-07 | 1997-08-08 | Atochem Elf Sa | SUPERABSORBENT POLYMERS WITH A HEART-SHELL STRUCTURE AND THEIR PROCESS FOR OBTAINING |
| EP1882701A1 (en) * | 2005-05-16 | 2008-01-30 | Sumitomo Seika Chemicals Co., Ltd. | Process for production of water-absorbing resin particles, water-absorbing resin particles made by the process, and absorbents and absorbent articles made by using the particles |
| DE102008014050A1 (en) | 2007-03-16 | 2008-09-18 | Murata Machinery Ltd. | Conveying device for removing plate material from a plate material processing machine comprises rails, a mobile receiving element for plate materials, driving elements and a conveying control unit for controlling the driving elements |
| WO2010074340A1 (en) | 2008-12-26 | 2010-07-01 | 花王株式会社 | Gas-barrier material, gas-barrier molded article, and method for producing the gas-barrier molded article |
| JP2010202743A (en) * | 2009-03-02 | 2010-09-16 | Nippon Shokubai Co Ltd | Method for producing water-absorptive resin |
| WO2011065368A1 (en) * | 2009-11-27 | 2011-06-03 | 住友精化株式会社 | Process for production of water-absorbing resin paticles, water-absorbing resin particles, water-stopping material, and absorbent article |
| CN102807680A (en) * | 2012-07-16 | 2012-12-05 | 大连理工大学 | Preparation method and application of mono-(6-oxy-ethylenediamine tetraacetyl)-cyclodextrin cross-linked polymer |
| JP2016521767A (en) * | 2013-05-17 | 2016-07-25 | アルケマ フランス | Surface crosslinking method for polymer particles |
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-
1993
- 1993-07-08 JP JP19267493A patent/JPH0726026A/en not_active Withdrawn
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0789048A1 (en) * | 1996-02-07 | 1997-08-13 | Elf Atochem S.A. | Superabsorbent polymers with core-shell structure and process for preparing same |
| FR2744456A1 (en) * | 1996-02-07 | 1997-08-08 | Atochem Elf Sa | SUPERABSORBENT POLYMERS WITH A HEART-SHELL STRUCTURE AND THEIR PROCESS FOR OBTAINING |
| EP1882701A4 (en) * | 2005-05-16 | 2010-11-03 | Sumitomo Seika Chemicals | Process for production of water-absorbing resin particles, water-absorbing resin particles made by the process, and absorbents and absorbent articles made by using the particles |
| EP1882701A1 (en) * | 2005-05-16 | 2008-01-30 | Sumitomo Seika Chemicals Co., Ltd. | Process for production of water-absorbing resin particles, water-absorbing resin particles made by the process, and absorbents and absorbent articles made by using the particles |
| US8003210B2 (en) | 2005-05-16 | 2011-08-23 | Sumitomo Seika Chemicals Co., Ltd. | Process for producing water-absorbing resin particles, water-absorbing resin particles made by the process, and absorbent materials and absorbent articles made by using the particles |
| DE102008014050A1 (en) | 2007-03-16 | 2008-09-18 | Murata Machinery Ltd. | Conveying device for removing plate material from a plate material processing machine comprises rails, a mobile receiving element for plate materials, driving elements and a conveying control unit for controlling the driving elements |
| WO2010074340A1 (en) | 2008-12-26 | 2010-07-01 | 花王株式会社 | Gas-barrier material, gas-barrier molded article, and method for producing the gas-barrier molded article |
| JP2010202743A (en) * | 2009-03-02 | 2010-09-16 | Nippon Shokubai Co Ltd | Method for producing water-absorptive resin |
| WO2011065368A1 (en) * | 2009-11-27 | 2011-06-03 | 住友精化株式会社 | Process for production of water-absorbing resin paticles, water-absorbing resin particles, water-stopping material, and absorbent article |
| US9320660B2 (en) | 2009-11-27 | 2016-04-26 | Sumitomo Seika Chemicals Co., Ltd. | Process for production of water-absorbing resin particles, water-absorbing resin particles, water-stopping material, and absorbent article |
| CN102807680A (en) * | 2012-07-16 | 2012-12-05 | 大连理工大学 | Preparation method and application of mono-(6-oxy-ethylenediamine tetraacetyl)-cyclodextrin cross-linked polymer |
| JP2016521767A (en) * | 2013-05-17 | 2016-07-25 | アルケマ フランス | Surface crosslinking method for polymer particles |
| CN113302229A (en) * | 2019-09-18 | 2021-08-24 | 株式会社Lg化学 | Superabsorbent polymer and method of making the same |
| JP2022512151A (en) * | 2019-09-18 | 2022-02-02 | エルジー・ケム・リミテッド | Highly absorbent resin and its manufacturing method |
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| JP2022016990A (en) * | 2020-07-13 | 2022-01-25 | 長瀬産業株式会社 | Water-absorbing resin crosslinker composition |
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