JPS60161410A - Preparation of solid resin having high water absorption property - Google Patents

Abstract

PURPOSE:To obtain the titled solid resin having high water absorption ability, preventing phenomena of formation of undissolved lump, by subjecting a monomer consisting of acrylic acid neutralized in a specific ratio and acrylamide, and a specified vinyl compound to aqueous solution polymerization, followed by drying. CONSTITUTION:(A) 100pts.wt. monomer having a molar ratio of acrylic acid to acrylamide of 70:30-100:0, wherein >=70mol% acrylic acid is ammonium, amine or alkali metal salt, and (B) 1-100pts.wt. hydroxy group-containing vinyl compound [e.g., hydroxyethyl(meth)acrylate, etc.] shown by the formula I [R is H, or CH3; M is group shown by the formula II (n is 1-10), or formula III] are subjected to aqueous solution polymerization, and dried, to give the desired solid resin. USE:Disposable diapers, napkins, medium for microorganisms, water retaining agent for horticulture, etc.

Description

【発明の詳細な説明】 本発明は水不溶性で自重の数百倍の水を吸収する高吸水
性樹脂の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a water-insoluble superabsorbent resin that absorbs several hundred times its own weight in water.

従来、水を吸収し保持するものとしては、バルブ製品が
使われてきた。しかしながら、バルブの吸水量は自重の
１０倍程度であり、多量の水を吸収保持しようとすると
バルブを多量に必要とし、大変かさ高いものとなってし
まい、また吸水したものに圧力を加えると簡単に水を分
離する欠点を有していた。Traditionally, valve products have been used to absorb and retain water. However, the amount of water absorbed by a valve is about 10 times its own weight, and if you try to absorb and retain a large amount of water, you will need a large amount of valves, which will be very bulky. However, it had the disadvantage of separating water.

そこで、わずかな重量で多量の水を吸収し、保持する高
吸水性樹脂の開発が種々なされてきた。この高吸水性樹
脂は自重の数百倍の水を吸収し、保持し、しかも吸水し
た状態で安定なゲルとなり、多少の圧力を加えても水を
分離しない特徴を有している。このような高吸水性樹脂
は使い捨ておむつ、ナプキン、微生物の培地、園芸用保
水剤等、巾広い用途を持っている。すでに開発されたも
のとしては、澱粉ダラフト重合体（％公昭５３−４６１
９９）、セルロース変成物（特開昭５Ｏ−８０３７６）
などがあるが、澱粉ダラフト重合体は含水ゲルとして長
期間使用した場合、腐敗するおそれがあり、セルロース
変成物では吸水量がセルロースに比較して、それ程多く
はないという欠点を有している。これらにかわるもの５
として、アクリル酸アルカリ金属塩をメチレンビスアク
リルアミド等のジビニル化合物の存在で重合した高吸水
性樹脂が提案されている（特開昭５８−７１９０７）。Therefore, various efforts have been made to develop super absorbent resins that absorb and retain large amounts of water with a small weight. This super-absorbent resin absorbs and retains several hundred times its own weight in water, and when it absorbs water, it becomes a stable gel, so it does not separate water even when a small amount of pressure is applied. Such superabsorbent resins have a wide range of uses, including disposable diapers, napkins, microbial culture media, and water retention agents for gardening. Among those that have already been developed are starch duraft polymers (% Kōsho 53-461).
99), modified cellulose (JP-A-5O-80376)
However, when used as a hydrogel for a long period of time, starch raft polymers may rot, and cellulose modified products have the disadvantage that they do not absorb as much water as cellulose. 5 alternatives to these
As such, a super absorbent resin prepared by polymerizing an alkali metal acrylic acid salt in the presence of a divinyl compound such as methylenebisacrylamide has been proposed (Japanese Unexamined Patent Publication No. 71907/1983).

しかしながら、このアクリル酸系の高吸水性樹脂粉末の
製造物を単量体に対して数百ｐｐｍという非常に少量用
いなければならず、架橋点が不均一となってしまう。そ
のため吸水後、一部のポリマーが溶出したり、また吸水
したゲルがべとつく等の欠点を有している。However, this acrylic acid-based super absorbent resin powder must be used in a very small amount of several hundred ppm relative to the monomer, resulting in non-uniform crosslinking points. Therefore, after water absorption, some of the polymers may be eluted, and the gel that has absorbed water may become sticky.

本発明者らは、この欠点を克服すべく鋭意研究をした結
果、本発明に到達した。The present inventors conducted extensive research to overcome this drawback, and as a result, they arrived at the present invention.

すなわち本発明はアクリル酸とアクリルアミドをモル比
で７０　：　３０〜１００：Ｏの範囲で、かつアクリル
酸の７０モルチ以上がアンモニウム、アミン、又はアル
カリ金属塩である単量体（八とアクリル酸とアクリルア
ミド１００重量部に対して１〜１０．Ｑ重量部の次式の
ヒドロオキシ基をもつビニル化合物（ト） ＣＨ２＝Ｃ−Ｃ−Ｍ−ＯＨ［Ｂ） Ｉ （但し、ＲはＨあるいはＣＨａを、−Ｍ−は＋０−ＣＨ
２−ＣＨ２すｎ　％０−ＣＩ−ｈ−ＣＨ＋ｎ、’　（ｎ
＝１〜１０）あＣＨ３ るいは−〇−Ｃ’［−１２−Ｃ）Ｉ−Ｃ）１２−を表わ
す。）晶 を必須成分として水溶液重合を行い乾燥することを特徴
とする高吸水性樹脂固体の製法に関するものである。That is, the present invention uses monomers in which the molar ratio of acrylic acid and acrylamide is in the range of 70:30 to 100:O, and 70 moles or more of acrylic acid is ammonium, amine, or alkali metal salt. A vinyl compound having a hydroxyl group of the following formula in an amount of 1 to 10.Q parts by weight per 100 parts by weight of acrylamide (T) CH2=C-C-M-OH[B) I (where R is H or CHa, -M- is +0-CH
2-CH2sn %0-CI-h-CH+n,' (n
=1 to 10) ACH3 or -〇-C'[-12-C)I-C)12-. ) The present invention relates to a method for producing a solid superabsorbent resin, which is characterized by carrying out aqueous polymerization and drying using crystals as an essential component.

本発明の特徴は単量体（Ａ）とヒドロキシル基をもつビ
ニル化合物ｔＢｌを共重合させ、架橋性ジビニル化合物
を特に用いない自己架橋性の高吸水性樹脂を提供すると
ころにある。高吸水性樹脂はほとんどの場合、水を含ま
ない粉末状で提供されることから、工程中に必ず脱水乾
燥工程が含まれる。本発明者らはこれに注目し、脱水乾
燥工程中に架橋し、水不溶性樹脂となる単量体を検討し
た結果、ヒドロオキシ基をもつビニル化合物とアクリル
酸塩を共重合することにより、その目的を達せられるこ
とが判り、本発明に到達した。これはアクリル酸のカル
ボキシル基とビニル化合物（均のヒドロオキシ基が脱水
乾燥工程でエステル化反応が起き、架橋し水不溶性樹脂
となるためだろう。これに類似のものとしてアクリル酸
塩を多価アルコールの存在下に重合する方法が提案され
ているが（特公昭５８−３５６０５）未反応の多価アル
コールが吸水ゲルから溶出分となり好１しくない。それ
に対し、本発明品は未反応のヒドロオキシ基もポリマー
中に共重合され溶出する心配が全くない。さらにこのヒ
ドロオキシ基が高吸水性樹脂粉末の表面に適度に分布す
るためか、吸水時に粉末が同寸ってしまう、いわゆる「
−！まこ」現象も防げることが判明した。The feature of the present invention is to copolymerize the monomer (A) with a vinyl compound tBl having a hydroxyl group to provide a self-crosslinkable superabsorbent resin that does not use a crosslinkable divinyl compound. Since superabsorbent resins are provided in powder form that does not contain water in most cases, a dehydration and drying step is always included in the process. The present inventors focused on this, and as a result of studying monomers that crosslink during the dehydration and drying process and become water-insoluble resins, we found that by copolymerizing a vinyl compound with a hydroxyl group and an acrylic acid salt, we achieved the desired goal. It has been found that the following can be achieved, and the present invention has been achieved. This is probably because an esterification reaction occurs between the carboxyl group of acrylic acid and the hydroxyl group of the vinyl compound during the dehydration and drying process, resulting in crosslinking and forming a water-insoluble resin. A method has been proposed (Japanese Patent Publication No. 58-35605) in which unreacted polyhydric alcohol is eluted from the water-absorbing gel, which is not preferable.On the other hand, the product of the present invention does not contain unreacted hydroxyl groups. There is no need to worry about copolymerization and elution into the polymer.Furthermore, perhaps because these hydroxyl groups are appropriately distributed on the surface of the super absorbent resin powder, the powder becomes the same size when water is absorbed, so-called "
-! It has been found that the "Mako" phenomenon can also be prevented.

また、ジビニル化合物を使用する場合、数百ｐｐｍＬか
用いられないのに対して、本発明品は１係以上のヒドロ
オキシ基をもつビニル化合物＋Ｂ）が用いられるため、
架橋も比較的、均一となり、吸水したゲルの表面がべと
つかないなど様々な利点が出てきた。In addition, when using a divinyl compound, only a few hundred ppmL is used, whereas in the product of the present invention, a vinyl compound +B) having a hydroxyl group of 1 or more is used.
The crosslinking became relatively uniform, and various advantages emerged, such as the surface of the water-absorbed gel not becoming sticky.

本発明の必須成分である単量体（Ｎについては、この範
囲外、すなわちアクリル酸が７０モルチ未満でアクリル
アミドのモル比を高めると含水ゲルの強度は高くなるが
吸水能が低下してし１い、また中和度を７０モルチ未満
にするとカルボキシル基の解離が充分でなく、吸水能の
低下が見られる。中和に要する塩基については特に限定
し力いが、−何階イオンが好せしい。Regarding the monomer (N), which is an essential component of the present invention, if the molar ratio of acrylamide is increased outside this range, that is, when acrylic acid is less than 70 molti, the strength of the hydrogel increases, but the water absorption capacity decreases. Furthermore, if the degree of neutralization is less than 70 molar, the dissociation of carboxyl groups will not be sufficient and a decrease in water absorption capacity will be observed.The base required for neutralization is particularly limited, but ions of -number order are preferred. Yes.

またヒドロオキシ基をもつビニル化合物（Ｂ）としては
、例えばヒドロオキシエチル（メタ）アクリレート、ヒ
ドロオキシプロピル（メタ）アクリレート、ポリ（ｎ−
２〜１０）エチレングリコールモノ（メタ）アクリレー
ト、ポリ（ｎ＝２〜１０）プロピレングリコールモノ（
メタ）アクリレート等があげられるが、ヒドロオキシエ
チル（メタ）アク’）レートが工業的に好ましい。ヒド
ロオキシ化合物（１（）の量はアクリル酸とアクリルア
ミド１００重量部に対して１〜１００重量部がよい。Examples of the vinyl compound (B) having a hydroxy group include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, poly(n-
2-10) Ethylene glycol mono(meth)acrylate, poly(n=2-10) propylene glycol mono(
Examples include meth)acrylate, but hydroxyethyl (meth)acrylate is industrially preferred. The amount of the hydroxy compound (1()) is preferably 1 to 100 parts by weight per 100 parts by weight of acrylic acid and acrylamide.

本発明品を重合するにあたって、開始剤は一般的に使用
されているレドックス系、アゾ系などどのようなものを
使用してもよく、特定の開始剤に限定されるものではな
い。重合開始温度については開始剤の種類によって異々
るために、使用する開始剤が機能する温度以上でよく、
特に限定されるものでない。In polymerizing the product of the present invention, any commonly used initiator, such as redox type or azo type, may be used, and the initiator is not limited to a specific one. The polymerization initiation temperature varies depending on the type of initiator, so it is sufficient to set it above the temperature at which the initiator used can function.
It is not particularly limited.

また重合濃度に関しては特に限定し々いが、乾燥工程を
考慮すると、できるだけ高濃度で行う方が有利である。The concentration of polymerization is particularly limited, but in consideration of the drying process, it is advantageous to carry out the polymerization at a concentration as high as possible.

脱水乾燥については含水した重合体をアセトン等の溶媒
で脱水し、その後１００℃以上で加熱乾燥する方法もあ
り、含水した重合体を直接１００℃以上の温度で乾燥す
る方法もある。また重合と乾燥を同時に行う方法として
、７０チ程度の高濃度水溶液で重合を行い、発生する重
合熱によりて水分を蒸発させてしまい、その１１粉砕工
程にもって行く有利な方法も選択できる。Regarding dehydration and drying, there is a method in which the hydrated polymer is dehydrated with a solvent such as acetone, and then heated and dried at 100°C or higher, and there is also a method in which the hydrated polymer is directly dried at a temperature of 100°C or higher. In addition, as a method for simultaneously carrying out polymerization and drying, an advantageous method can be selected in which polymerization is carried out using a highly concentrated aqueous solution of about 70%, water is evaporated by the generated heat of polymerization, and the water is then brought to the pulverization step 11.

次に本発明を実施例に基づいて更に具体的に説明するが
、本発明はその要旨を超えない限り、以下の実施例に制
約されるものではない。Next, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

実施例１ アクリル酸５２７ｔとアクリルアミド１７３ｆを蒸留水
１００ｔに溶解し、これに水酸化ナトリウム２３．４ｆ
を加え、アクリル酸の８０モルｑｂを部分中和した。こ
れにヒドロオキシメタアクリレート３５２を加え、攪拌
して均一にした。次に開始剤として過硫酸アンモニウム
０．０２８Ｆ、亜硫酸水素ナトリウム０．０２８ｆを添
加し、５０℃にて重合を開始させた。Example 1 527t of acrylic acid and 173f of acrylamide were dissolved in 100t of distilled water, and 23.4f of sodium hydroxide was added to the solution.
was added to partially neutralize 80 mol qb of acrylic acid. Hydroxymethacrylate 352 was added to this and stirred to make it homogeneous. Next, 0.028 F of ammonium persulfate and 0.028 F of sodium bisulfite were added as initiators, and polymerization was started at 50°C.

この含水した重合物をカッターで約５膿の厚さにスライ
スし、１０５℃の乾燥機で２時間加温し乾燥し、高吸水
性樹脂固体を得た。This water-containing polymer was sliced with a cutter to a thickness of about 5 mm, and dried by heating in a dryer at 105° C. for 2 hours to obtain a superabsorbent resin solid.

実施例２ アクリル酸７０ｆを蒸留水２０２に溶解し、これに水酸
化カリウム４０８２を加えてアクリル酸の７５モルチを
中和した。Example 2 Acrylic acid 70f was dissolved in distilled water 202, and potassium hydroxide 4082 was added thereto to neutralize 75 mol of acrylic acid.

これにヒドロオキシアクリレートをＬｏｆ加え攪拌して
均、−にした。次に開始剤として２．２′−アゾビスイ
ソブチルニトリル０．７２を溶解したアセトン溶液をｌ
０ＣＣカロえた。この溶液を８０℃の恒温水槽で加湛さ
れた箱型容器（テフロン加工したガラス繊維素材）の中
に入れて加熱した。溶液の温度が上昇すると共に重合反
応が開始し、発生する重合熱（でよって水分が蒸発し、
含水率の非常に低い多孔性の白色固体として高吸水性樹
脂を得た。Lof of hydroxyacrylate was added to this and stirred until the mixture was evenly mixed. Next, add 1 liter of an acetone solution containing 0.72% of 2.2'-azobisisobutylnitrile as an initiator.
I gained 0CC. This solution was heated in a box-shaped container (Teflon-treated glass fiber material) filled with a constant temperature water bath at 80°C. As the temperature of the solution rises, the polymerization reaction starts, and the heat of polymerization (as a result, water evaporates,
A superabsorbent resin was obtained as a porous white solid with a very low water content.

実施例３ アクリル酸７０２に２９チアンモニア水を３９．９ｆを
加えア　−クリル酸の７０モル％を中和した。これにヒ
ドロオキシメタクリレートを１５ｆ加え攪拌して均一に
した。次に開始剤として２．２′−アゾビス（２−アミ
ジノプロパン）ハイドロクロライド０．７ｆｆ加えた。Example 3 39.9f of 29thiammonium water was added to acrylic acid 702 to neutralize 70 mol% of the acrylic acid. 15 f of hydroxy methacrylate was added to this and stirred to make it homogeneous. Next, 0.7 ff of 2,2'-azobis(2-amidinopropane) hydrochloride was added as an initiator.

この溶液を前述の箱型容器の中に入れて力口熱し、重合
を開始させた。重合反応が進み発生する重合熱によって
水分が蒸発し、含水率の非常に低い多孔性の白色固体と
して高吸水性樹脂を得た。This solution was placed in the aforementioned box-shaped container and heated to initiate polymerization. Water was evaporated by the heat of polymerization generated as the polymerization reaction progressed, and a super absorbent resin was obtained as a porous white solid with a very low water content.

比較例１ アクリル酸７０１を蒸留水２０ｆに溶解し、これに水酸
化カリウム４０８２を加えてアクリル酸の７５モルチを
中和した。Comparative Example 1 Acrylic acid 701 was dissolved in 20 f of distilled water, and potassium hydroxide 4082 was added thereto to neutralize 75 mol of acrylic acid.

これにＮ、Ｎ−メチレンビスアクリルアミド’ｅｏ、ｏ
ｏ’ｌ加えて攪拌し均一に溶解した。次に開始剤として
２．２′−アゾビスイノブチロニトリル０．７１を溶解
したアセトン溶液を１０ＬＪ−加えた。この溶液を前述
の箱型容器の中に入れて加熱し、重合を開始させた。重
合反応が進み発生する重合熱によって水分が蒸発し、含
水率の非常に低い多孔性の白色固体として高吸水性樹脂
を得た。This is combined with N,N-methylenebisacrylamide'eo,o
o'l was added and stirred to uniformly dissolve. Next, 10 LJ of an acetone solution containing 0.71 g of 2,2'-azobisinobutyronitrile dissolved therein was added as an initiator. This solution was placed in the aforementioned box-shaped container and heated to initiate polymerization. Water was evaporated by the heat of polymerization generated as the polymerization reaction progressed, and a super absorbent resin was obtained as a porous white solid with a very low water content.

実施例４ 実施例１〜３、及び比較例１で得られた重合物固体を粉
砕し、粉末状の高吸水性樹脂を得た。それぞれの粉末の
吸水性能を見るために次の試験を行った。蒸留水２ｔを
ビーカーに入れマグネティック・スターラーで弱攪拌し
、その中に高吸水性樹脂の粉末（２０−６０ｍｅｓｈ　
）　１　ｆを加えた。１０分後、１００　ｍｅｓｈのふ
るいを用いて濾過し、テ液量から吸水量を測定した。そ
の結果は吸水倍率（吸水量÷加えた高吸水性樹脂の重量
）によって表１に示した。また同様の試験を１６１ｂ食
に比べ、「ままこ」になりに＜＜、また吸水ゲルのへと
つきもなく、優れた性能をもつことが判明した。Example 4 The polymer solids obtained in Examples 1 to 3 and Comparative Example 1 were pulverized to obtain a powdery superabsorbent resin. The following test was conducted to examine the water absorption performance of each powder. Pour 2 tons of distilled water into a beaker, stir gently with a magnetic stirrer, and add super absorbent resin powder (20-60 mesh) into the beaker.
) 1 f was added. After 10 minutes, the mixture was filtered using a 100 mesh sieve, and the amount of water absorbed was measured from the amount of liquid. The results are shown in Table 1 in terms of water absorption capacity (water absorption amount ÷ weight of added super absorbent resin). Furthermore, when compared with the 161b diet in a similar test, it was found that the food had excellent performance, with no ``mamako'' texture and no stickiness of the water-absorbing gel.

表１　吸水性酔（蒸留水） 表２　吸水性能（１％食塩水） 手続補正書（方式） 昭和５９年５月８日 特許庁長官殿 １、事件の表示　昭和５９年特許願第１５２８０号２、
発明の名称 ３、補正をする者 事件との関係　特許出願人 ぐ念べTable 1 Water absorption intoxication (distilled water) Table 2 Water absorption performance (1% saline) Procedural amendment (method) May 8, 1980 Mr. Commissioner of the Japan Patent Office 1, Indication of case 1982 Patent Application No. 15280 2 ,
Title of the invention 3. Relationship with the case of the person making the amendment A note for patent applicants

Claims (1)

【特許請求の範囲】 １、アクリル酸とアクリルアミドをモル比で７０：３０
〜ｔｏｏ：ｏの範囲で、かつ、アクリル酸の７０モルチ
以上がアンモニウム、アミン、又はアルカリ金属塩であ
る単量体（Ａ）と、アクリル酸とアクリルアミド１００
重量部に対して１〜１００重量部の次式のヒドロオキシ
基をもつビニル化合物の） ＣＩ（２＝Ｃ−Ｃ−Ｍ−ＯＨ’　（１３）（但し、Ｒは
ＨあるいはＣＨａを、−Ｍ−はモ０−ＣＨ２−ＣＨ２す
ｎ　％０−ＣＨ２−ＣＨ＋ｎ　（ｎ＝１〜ＣＨａ １０）あるいは−〇　−ＣＨ２−ＣＨ−ＣＨ２−を表わ
曳）ＯＨ を必須成分として水溶液重合を行い、乾燥することを特
徴とする高吸水性樹脂固体の製法[Claims] 1. Acrylic acid and acrylamide in a molar ratio of 70:30
A monomer (A) in which 70 moles or more of acrylic acid is ammonium, amine, or alkali metal salt, and acrylic acid and acrylamide 100 in the range of ~too:o
CI (2=C-C-M-OH' (13) of a vinyl compound having a hydroxyl group of the following formula in an amount of 1 to 100 parts by weight per part by weight, where R is H or CHa, -M- %0-CH2-CH+n (n = 1 to CHa 10) or -0 -CH2-CH-CH2-) Perform aqueous polymerization with OH as an essential component and dry. A method for producing a superabsorbent resin solid characterized by