JP3103754B2 - Modified water-absorbing resin particles and method for producing the same - Google Patents
Modified water-absorbing resin particles and method for producing the sameInfo
- Publication number
- JP3103754B2 JP3103754B2 JP07308276A JP30827695A JP3103754B2 JP 3103754 B2 JP3103754 B2 JP 3103754B2 JP 07308276 A JP07308276 A JP 07308276A JP 30827695 A JP30827695 A JP 30827695A JP 3103754 B2 JP3103754 B2 JP 3103754B2
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- JP
- Japan
- Prior art keywords
- water
- resin particles
- absorbent resin
- particles
- acrylate
- 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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- Compositions Of Macromolecular Compounds (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、改質された吸水性
樹脂粒子およびその製法に関する。更に詳しくは、吸水
性樹脂粒子を加熱表面架橋した後に水を添加して含水率
を特定範囲に調節することにより、機械的作用が加わっ
た場合の粒子の壊れ性（破断応力）および粒子脆さを改
質した吸水性樹脂粒子およびその製法に関する。The present invention relates to modified water-absorbent resin particles and a method for producing the same. More specifically, by adding water after heating and cross-linking the water-absorbent resin particles to adjust the water content to a specific range, the breakability (rupture stress) and particle brittleness of the particles when a mechanical action is applied. The present invention relates to a water-absorbent resin particle obtained by modifying the above and a method for producing the same.
【０００２】[0002]
【従来の技術】従来から、生理用品、紙おむつなどの衛
生材料用途に吸水性樹脂が幅広く用いられている。この
様な吸水性樹脂としては、例えば、ポリアクリル酸塩架
橋物、自己架橋型ポリアクリル酸塩、デンプン−アクリ
ル酸塩グラフト共重合体架橋物などの、実質的に水不溶
性の架橋重合体が知られている。近年、これら吸水性樹
脂の吸収特性およびゲル物性を改良する目的で、吸水性
樹脂粒子の表面近傍をアクリル酸および／またはアクリ
ル酸塩と反応しうる官能基を２個以上有する架橋剤で加
熱架橋された、いわゆる表面架橋型の吸水性樹脂が登場
している。2. Description of the Related Art Conventionally, water-absorbent resins have been widely used for sanitary materials such as sanitary products and disposable diapers. As such a water-absorbing resin, for example, a substantially water-insoluble cross-linked polymer such as a cross-linked polyacrylate, a self-cross-linked polyacrylate, a cross-linked starch-acrylate graft copolymer, etc. Are known. In recent years, in order to improve the absorption characteristics and gel properties of these water-absorbent resins, heat-crosslinking of the vicinity of the surface of the water-absorbent resin particles with a crosslinking agent having two or more functional groups capable of reacting with acrylic acid and / or acrylate. So-called surface cross-linking type water-absorbing resin has appeared.
【０００３】[0003]
【発明が解決しようとする課題】しかし、これらの加熱
架橋された表面架橋型の吸水性樹脂は、従来の非加熱表
面架橋型吸水性樹脂に比べて、優れた吸収特性とゲル物
性を発現するが、粒子表面近傍の架橋密度が高いこと、
および加熱架橋操作の過程で水分が蒸散して粒子の含水
率が低いことから、樹脂粒子は硬く、且つ脆くなる。そ
の結果、吸水性樹脂粒子を使用する場面、例えばスクリ
ューコンベアーやスプリングコンベアー等による機械的
な粉体輸送あるいは空気圧による粉体輸送、スクリュー
フィーダー等による粉体散布や供給、空気圧によるスプ
レー散布などの過程において、粒子同士の衝突、機械や
設備の壁面への粒子の衝突、機械的摩擦などによって吸
水性樹脂粒子が壊れて粒度分布が変化するという問題を
生じる。更に、粒子が壊れることによって表面架橋の効
果を損なう、粒子が壊れて微粒子が生成して粉塵の原因
となるという問題も生じる。また、微粒子が増加するこ
とにより、吸収性能やゲル物性が悪化するという問題が
発生する。従って、吸水性樹脂粒子を多量に使用するあ
らゆる場面において、これらの問題の解決が望まれてい
る。However, these heat-crosslinked surface-crosslinkable water-absorbent resins exhibit superior absorption characteristics and gel physical properties as compared with conventional non-heated surface-crosslinkable water-absorbent resins. Has a high crosslinking density near the particle surface,
In addition, the resin particles are hard and brittle because water evaporates during the heat crosslinking operation and the water content of the particles is low. As a result, when water-absorbing resin particles are used, for example, mechanical powder transportation using a screw conveyor or a spring conveyor or pneumatic powder transportation, powder spraying and supply using a screw feeder, etc., and processes such as pneumatic spraying In this case, there is a problem that the water-absorbent resin particles are broken due to the collision of particles, the collision of the particles with a wall of a machine or equipment, the mechanical friction, and the like, and the particle size distribution is changed. Further, there is a problem that the effect of surface cross-linking is impaired by breaking the particles, and that the particles are broken to form fine particles and cause dust. In addition, there is a problem that the absorption performance and the physical properties of the gel are deteriorated due to the increase of the fine particles. Therefore, it is desired to solve these problems in all situations where a large amount of water-absorbent resin particles are used.
【０００４】[0004]
【課題を解決するための手段】本発明者らは、上記の問
題点を解決すべく鋭意検討した結果、吸水性樹脂粒子の
加熱表面架橋後に水を添加して含水率を特定の範囲に調
整することによって、粒子の破断応力がアップし、粒子
の脆さが軽減され、機械的剪断力によっても壊れにくい
粒子が得られることを見いだし、本発明に到達した。Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, added water after heating and surface crosslinking of the water-absorbent resin particles to adjust the water content to a specific range. By doing so, it has been found that the breaking stress of the particles is increased, the brittleness of the particles is reduced, and the particles are hardly broken even by mechanical shearing force.
【０００５】すなわち本発明は、アクリル酸および／ま
たはアクリル酸塩を主構成単位とし、且つ該アクリル酸
および／またはアクリル酸塩と反応しうる官能基を２個
以上有する架橋剤で粒子表面近傍が加熱架橋された吸水
性樹脂粒子に、加熱架橋後に水に対する濃度が５〜５０
重量％である無機の塩を溶解している水および／または
無機の水酸化物を溶解している水を添加して含水率を３
〜９％に調整することを特徴とする粒子脆さの改質され
た吸水性樹脂粒子の製法；並びにアクリル酸および／ま
たはアクリル酸塩を主構成単位とし、且つ該アクリル酸
および／またはアクリル酸塩と反応しうる官能基を２個
以上有する架橋剤で粒子表面近傍が加熱架橋された吸水
性樹脂粒子に、水に対する濃度が５〜５０重量％である
無機の塩を溶解している水および／または無機の水酸化
物を溶解している水を添加して得られる、含水率が３〜
９％であり、粒子の破断応力が３０Ｎ／ｍ2以上である
粒子脆さの改質された吸水性樹脂粒子である。That is, the present invention relates to a cross-linking agent having acrylic acid and / or acrylate as a main constituent unit and having two or more functional groups capable of reacting with the acrylic acid and / or acrylate, so that the vicinity of the particle surface is reduced. The heat-crosslinked water-absorbent resin particles have a concentration in water of 5 to 50 after heat-crosslinking.
By adding water in which an inorganic salt and / or an inorganic hydroxide are dissolved, the water content is 3% by weight.
A method for producing water-absorbent resin particles having modified particle brittleness, characterized in that the content is adjusted to ９9%; and acrylic acid and / or acrylate as a main constituent unit, and said acrylic acid and / or acrylic acid Water in which an inorganic salt having a concentration of 5 to 50% by weight with respect to water is dissolved in water-absorbent resin particles whose surface is crosslinked by heating with a crosslinking agent having two or more functional groups capable of reacting with a salt; Water content of 3 to 3 obtained by adding water in which an inorganic hydroxide is dissolved.
It is a water-absorbent resin particle of 9% in which the breaking stress of the particle is 30 N / m 2 or more and the particle embrittlement is modified.
【０００６】[0006]
【発明の実施の形態】本発明において、吸水性樹脂粒子
としては、水と接触したときに多量の水を吸収・膨潤し
て含水ゲル状物（ヒドロゲル）を形成する、実質的に水
不溶性の樹脂（吸水性樹脂）の粒子であり、アクリル酸
および／またはアクリル酸塩と反応しうる官能基を２個
以上有する架橋剤で粒子表面近傍が加熱架橋されている
吸水性樹脂粒子である。このような表面架橋型の吸水性
樹脂としては、特に限定はないが、例えば、表面架橋さ
れたポリアクリル酸部分中和物の架橋体、表面架橋され
た自己架橋型ポリアクリル酸部分中和物、表面架橋され
たデンプン／アクリル酸塩グラフト共重合体架橋物、表
面架橋されたデンプン−アクリロニトリルグラフト重合
体架橋物の加水分解物、表面架橋されたビニルアルコー
ル／アクリル酸塩共重合体、表面架橋されたアクリル酸
塩／アクリルアミド共重合体架橋物もしくはアクリル酸
塩／アクリロニトリル共重合体架橋物の加水分解物、表
面架橋されたアクリル酸塩と２−アクリルアミド−２−
メチルプロパンスルホン酸塩の共重合体架橋物などの１
種以上が挙げられる。尚、上記において塩としては、ナ
トリウム塩、カリウム塩、アンモニウム塩、アミン塩な
どが一般に用いられる。これらのうち好ましいものは、
最終的に得られる吸水性樹脂の吸収特性を考えると、ア
クリル酸および／またはアクリル酸塩を主構成単位とす
るエチレン性不飽和単量体の架橋重合体であり、実質的
に水不溶性の加熱表面架橋された吸水性樹脂粒子であ
る。尚、アクリル酸および／またはアクリル酸塩と常温
で反応しうる架橋剤（例えば多価金属塩など）を用い、
加熱操作を加えることなく表面架橋された吸水性樹脂粒
子は本発明の範囲には含まれない。BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the water-absorbing resin particles are substantially water-insoluble, forming a hydrogel by absorbing and swelling a large amount of water when contacted with water. Resin (water-absorbent resin) particles are water-absorbent resin particles in which the vicinity of the particle surface is heat-crosslinked with a crosslinking agent having two or more functional groups capable of reacting with acrylic acid and / or acrylate. Such surface-crosslinked type water-absorbing resin is not particularly limited. For example, a cross-linked product of a surface-crosslinked polyacrylic acid partially neutralized product, a surface-crosslinked self-crosslinked polyacrylic acid partially neutralized product Surface crosslinked starch / acrylate graft copolymer crosslinked, surface crosslinked starch-acrylonitrile graft polymer crosslinked hydrolyzate, surface crosslinked vinyl alcohol / acrylate copolymer, surface crosslink Crosslinked acrylate / acrylamide copolymer or hydrolyzate of crosslinked acrylate / acrylonitrile copolymer, surface crosslinked acrylate and 2-acrylamide-2-
1 such as cross-linked copolymer of methyl propane sulfonate
Species or more. In the above, sodium salts, potassium salts, ammonium salts, amine salts and the like are generally used as the salts. Preferred of these are:
Considering the absorption characteristics of the water-absorbing resin finally obtained, it is a crosslinked polymer of an ethylenically unsaturated monomer having acrylic acid and / or acrylate as a main constituent unit, and is substantially insoluble in water. Surface-crosslinked water-absorbent resin particles. In addition, using a crosslinking agent (for example, a polyvalent metal salt or the like) that can react with acrylic acid and / or acrylate at room temperature,
Water-absorbing resin particles that have been surface-crosslinked without adding a heating operation are not included in the scope of the present invention.
【０００７】該吸水性樹脂粒子の形状は特に限定はな
く、製法の違いにより、リン片状、塊状、岩状、パール
状あるいは無定形状、およびこれら粒子の造粒物等が挙
げられるが、いずれであってもよい。本発明の効果が顕
著であるという点で好ましい形状は、リン片状、塊状、
岩状あるいは無定形状である。また、粒径あるいは粒度
分布についても特に限定はなく、通常約１０〜１，００
０ミクロン、好ましくは約１００〜８５０ミクロンの粒
子が９０重量％以上の粒度分布であり、且つ平均粒径が
２００〜７００ミクロンの粒子である。The shape of the water-absorbent resin particles is not particularly limited, and may be in the form of flakes, lumps, rocks, pearls or amorphous shapes, or granules of these particles, depending on the production method. Any of them may be used. Preferred shapes in that the effects of the present invention are remarkable, flaky, massive,
It is rocky or amorphous. There is no particular limitation on the particle size or the particle size distribution, and usually about 10 to 1,000.
Particles of 0 micron, preferably about 100-850 micron, have a particle size distribution of 90% by weight or more, and have an average particle diameter of 200-700 micron.
【０００８】本発明において、吸水性樹脂粒子の表面近
傍を架橋するのに用いられる架橋剤としては、アクリル
酸および／またはアクリル酸塩と反応しうる官能基を２
個以上有する架橋剤であり、例えば、ポリグリシジルエ
ーテル系化合物、多価アルコール系化合物、ポリアミン
系化合物あるいはポリアミン系樹脂などが挙げられる。
これらの架橋剤を吸水性樹脂粒子のアクリル酸および／
またはアクリル酸塩と架橋反応させるには加熱操作を必
要とするのが通常である。In the present invention, the cross-linking agent used for cross-linking the vicinity of the surface of the water-absorbent resin particles includes a functional group capable of reacting with acrylic acid and / or acrylate.
It is a crosslinking agent having at least one compound, such as a polyglycidyl ether compound, a polyhydric alcohol compound, a polyamine compound, or a polyamine resin.
These cross-linking agents are added to the water-absorbent resin particles of acrylic acid and / or
Alternatively, a heating operation is usually required to cause a crosslinking reaction with the acrylate.
【０００９】ポリグリシジルエーテル系化合物の具体例
としては、エチレングリコールジグリシジルエーテル、
プロピレングリコールジグリシジルエーテル、グリセリ
ン−１，３−ジグリシジルエーテル、グリセリントリグ
リシジルエーテル、ポリエチレングリコールジグリシジ
ルエーテル、１，６−ヘキサンジオールジグリシジルエ
ーテル、ポリグリセロールポリグリシジルエーテル等が
挙げられる。多価アルコール系化合物の具体例として
は、グリセリン、エチレングリコール、ジエチレングリ
コール、プロピレングリコール、ポリエチレングリコー
ル、ポリプロピレングリコール、ジエタノールアミン、
トリエタノールアミン等が挙げられる。ポリアミン系化
合物あるいはポリアミン系樹脂の具体例としては、エチ
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、ポリアミンと脂
肪酸との反応物であるポリアミド樹脂、ポリアミンエピ
クロルヒドリン樹脂、ポリアミドポリアミンエピクロル
ヒドリン樹脂等が挙げられる。該表面架橋剤として例示
したもののうち好ましいものは、ポリグリシジルエーテ
ル系化合物、多価アルコール系化合物およびポリアミン
系化合物である。更に好ましいものは、エチレングリコ
ールジグリシジルエーテル、プロピレングリコールジグ
リシジルエーテル、グリセリン−１，３−ジグリシジル
エーテル、グリセリントリグリシジルエーテル、ポリグ
リセロールポリグリシジルエーテル、グリセリン、エチ
レングリコール、ジエチレングリコール、ポリアミドポ
リアミンエピクロルヒドリン樹脂である。Specific examples of the polyglycidyl ether compound include ethylene glycol diglycidyl ether,
Examples include propylene glycol diglycidyl ether, glycerin-1,3-diglycidyl ether, glycerin triglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and polyglycerol polyglycidyl ether. Specific examples of polyhydric alcohol compounds include glycerin, ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, diethanolamine,
Triethanolamine and the like. Specific examples of the polyamine-based compound or polyamine-based resin include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, a polyamide resin that is a reaction product of a polyamine and a fatty acid, a polyamine epichlorohydrin resin, a polyamide polyamine epichlorohydrin resin, and the like. . Preferred examples of the surface crosslinking agent include polyglycidyl ether compounds, polyhydric alcohol compounds and polyamine compounds. More preferred are ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerin-1,3-diglycidyl ether, glycerin triglycidyl ether, polyglycerol polyglycidyl ether, glycerin, ethylene glycol, diethylene glycol, and polyamide polyamine epichlorohydrin resin. is there.
【００１０】本発明において該表面架橋剤の使用量は、
架橋剤の種類、吸水性樹脂の種類およびその架橋度、得
られる改質された吸水性樹脂の性能目標などによっても
異なるが、吸水性樹脂：架橋剤の重量比で、通常１０
０：０．０１〜５、好ましくは１００：０．０２〜２、
特に好ましくは１００：０．０５〜１の範囲である。こ
の架橋剤の比率が０．０１未満では表面架橋の効果が十
分発現せず、反対に５より多い場合は表面架橋の密度が
過大となりすぎて吸収量の低下をまねく。In the present invention, the amount of the surface crosslinking agent used is:
Depending on the type of the crosslinking agent, the type of the water-absorbing resin and the degree of crosslinking thereof, and the performance target of the resulting modified water-absorbing resin, the weight ratio of the water-absorbing resin to the crosslinking agent is usually 10%.
0: 0.01 to 5, preferably 100: 0.02 to 2,
Particularly preferably, it is in the range of 100: 0.05 to 1. If the ratio of the crosslinking agent is less than 0.01, the effect of the surface crosslinking is not sufficiently exhibited, while if it is more than 5, the density of the surface crosslinking becomes excessively large and the absorption amount is reduced.
【００１１】本発明において、表面架橋の方法について
は特に限定はなく従来からの方法が適用でき、例えば、
有機溶剤と水との混合溶媒に架橋剤を溶解して吸水性樹
脂粒子と混合した後に加熱架橋する方法、水溶性化合物
の水溶液に架橋剤を溶解して吸水性樹脂粒子と混合した
後に加熱架橋する方法、高速攪拌状態の吸水性樹脂粒子
に架橋剤水溶液を添加した後に加熱架橋する方法などが
挙げられる。尚、架橋剤溶液の混合と加熱架橋操作とを
同時に同じ装置内で行うこともできる。上記の加熱架橋
後に吸水性樹脂粒子を冷却する操作を加えても良い。い
ずれの方法においても、表面架橋反応に当たっては、反
応の場として水の存在を必要とするのが通常である。In the present invention, the method of surface crosslinking is not particularly limited, and a conventional method can be applied.
A method in which a crosslinking agent is dissolved in a mixed solvent of an organic solvent and water and mixed with water-absorbing resin particles and then heat-crosslinked, and a method in which the crosslinking agent is dissolved in an aqueous solution of a water-soluble compound and mixed with the water-absorbing resin particles and then heat-crosslinked And a method in which a crosslinking agent aqueous solution is added to the water-absorbing resin particles in a high-speed stirring state, followed by heat crosslinking. Incidentally, the mixing of the crosslinking agent solution and the heating crosslinking operation can be performed simultaneously in the same apparatus. An operation of cooling the water-absorbent resin particles after the above-mentioned heat crosslinking may be added. In any of the methods, the surface crosslinking reaction usually requires the presence of water as a reaction site.
【００１２】加熱架橋の条件についても特に限定はない
が、効率的な架橋反応を行わせるためには通常１００〜
２００℃、好ましくは１２０〜１８０℃の温度が必要で
あり、加熱時間は通常５〜１２０分、好ましくは１０〜
９０分である。この様な加熱条件で表面架橋された後の
吸水性樹脂粒子は、反応溶媒の蒸発により、通常含水率
は２％以下となる。加熱架橋条件によっては含水率が１
％以下になる場合がある。The conditions for the heat crosslinking are not particularly limited, but are usually 100 to 100% in order to carry out an efficient crosslinking reaction.
A temperature of 200 ° C., preferably 120 to 180 ° C. is required, and the heating time is usually 5 to 120 minutes, preferably 10 to 120 minutes.
90 minutes. The water content of the water-absorbent resin particles after the surface cross-linking under such heating conditions usually becomes 2% or less due to evaporation of the reaction solvent. Moisture content is 1 depending on heat crosslinking conditions
%.
【００１３】本発明において、加熱架橋後に添加する水
の量は、最終的に得られる吸水性樹脂粒子の含水率が３
〜９％にできれば特に限定はないが、該吸水性樹脂粒子
の重量に対して通常２〜１５重量％であり、好ましくは
３〜１２重量％、更に好ましくは３〜９重量％である。
添加する水の量が２重量％未満の場合、粒子の破断応力
を改善する効果が殆ど認められない。また、加熱架橋後
の吸水性樹脂粒子の温度が高い場合には添加した水の大
部分が蒸発してしまうため、本発明の効果が得られなく
なる。一方、１５重量％を越える水を添加しても、水の
添加に見合う粒子の破断応力の改善効果が得られないこ
とから非経済的である。更に、多量の水を添加すること
から粒子同士のブロッキングにより塊状物を生じやすく
なり、均一な含水率を有する粒子が得られないという別
の問題が発生する。ここで、添加する水の量が目的とす
る含水率よりも多い量であるのは、加熱架橋後の吸水性
樹脂粒子の温度が高い状態で水を添加した場合、添加し
た水の一部が蒸発するため、この蒸発分を見込んで多め
に添加する必要があるためである。従って、加熱表面架
橋後に吸水性樹脂粒子を冷却する操作を加えた場合に
は、冷却操作を加えない場合に比べて添加する水の量は
少なくてよい。In the present invention, the amount of water to be added after the heat crosslinking is such that the water content of the finally obtained water-absorbing resin particles is 3%.
There is no particular limitation as long as the content can be reduced to 9%, but it is usually 2 to 15% by weight, preferably 3 to 12% by weight, more preferably 3 to 9% by weight based on the weight of the water-absorbent resin particles.
When the amount of water to be added is less than 2% by weight, the effect of improving the breaking stress of the particles is hardly recognized. Further, when the temperature of the water-absorbent resin particles after the heat crosslinking is high, most of the added water evaporates, so that the effect of the present invention cannot be obtained. On the other hand, even if more than 15% by weight of water is added, the effect of improving the breaking stress of the particles corresponding to the addition of water cannot be obtained, which is uneconomical. Further, since a large amount of water is added, agglomerates are easily generated due to blocking between particles, and another problem occurs in that particles having a uniform moisture content cannot be obtained. Here, the amount of water to be added is larger than the target water content because, when water is added in a state where the temperature of the water-absorbent resin particles after heat crosslinking is high, a part of the added water is This is because, in order to evaporate, it is necessary to add a large amount in anticipation of this evaporation. Therefore, when an operation of cooling the water-absorbent resin particles is added after the heating surface cross-linking, the amount of water to be added may be smaller than in the case where the cooling operation is not added.
【００１４】吸水性樹脂粒子に水を添加する際に粒子同
士のブロッキングを生じさせない目的で、必要により水
に無機の塩および／または無機の水酸化物を溶解して添
加することができる。このような無機の塩としては、ア
ルカリ金属塩、アルカリ土類金属塩、アルミニウム塩か
ら選ばれる少なくとも１種の無機塩が挙げられる。無機
の水酸化物としては、水酸化アルミニウム、水酸化マグ
ネシウムなどが挙げられる。For the purpose of preventing the particles from blocking each other when water is added to the water-absorbent resin particles, if necessary, an inorganic salt and / or an inorganic hydroxide can be dissolved in water and added. Examples of such inorganic salts include at least one inorganic salt selected from alkali metal salts, alkaline earth metal salts, and aluminum salts. Examples of the inorganic hydroxide include aluminum hydroxide and magnesium hydroxide.
【００１５】無機アルカリ金属塩の具体例としては、塩
化ナトリウム、硫酸ナトリウム、炭酸ナトウム、リン酸
ナトリウム、ナトリウム明礬、塩化カリウム、硫酸カリ
ウム、炭酸カリウム、リン酸カリウム、カリウム明礬な
どが挙げられる。無機アルカリ土類金属塩の具体例とし
ては、塩化カルシウム、塩化マグネシウム、硫酸マグネ
シウムなどが挙げられる。無機アルミニウム塩の具体例
としては、塩化アルミニウム、硫酸アルミニウムなどが
挙げられる。好ましい無機塩は無機アルカリ金属塩であ
り、特に好ましいものは硫酸ナトリウム、炭酸ナトウ
ム、リン酸ナトリウム、ナトリウム明礬である。Specific examples of the inorganic alkali metal salt include sodium chloride, sodium sulfate, sodium carbonate, sodium phosphate, sodium alum, potassium chloride, potassium sulfate, potassium carbonate, potassium phosphate, potassium alum and the like. Specific examples of the inorganic alkaline earth metal salt include calcium chloride, magnesium chloride, magnesium sulfate and the like. Specific examples of the inorganic aluminum salt include aluminum chloride and aluminum sulfate. Preferred inorganic salts are inorganic alkali metal salts, and particularly preferred are sodium sulfate, sodium carbonate, sodium phosphate and sodium alum.
【００１６】該無機の塩の水に対する濃度は無機塩の種
類や添加する水の量によって種々変化させることができ
るが、通常５〜５０重量％、好ましくは１０〜４０重量
％である。濃度が５重量％未満の場合、通常の混合では
水添加時のブロッキングを防止する効果に乏しく、一
方、濃度が５０重量％を越えてもブロッキングを防止す
る効果に顕著な向上は認められず、且つ吸収性能が低下
する結果を招き好ましくない。The concentration of the inorganic salt in water can be varied depending on the kind of the inorganic salt and the amount of water to be added, but is usually 5 to 50% by weight, preferably 10 to 40% by weight. When the concentration is less than 5% by weight, the effect of preventing blocking at the time of adding water is poor in ordinary mixing. On the other hand, even when the concentration exceeds 50% by weight, no significant improvement in the effect of preventing blocking is observed. In addition, the absorption performance is lowered, which is not preferable.
【００１７】本発明において、該吸水性樹脂粒子に水を
添加する方法としては、攪拌羽根を備えた攪拌混合装置
内でおこなうのが好ましい。例えば、攪拌混合装置内に
供給された吸水性樹脂粒子を攪拌しながら水（または無
機塩を溶解した水）を噴霧あるいは滴下する方法が挙げ
られる。噴霧や滴下に当たっては、所定量の一括添加あ
るいは分割添加のいずれでもよい。In the present invention, the method of adding water to the water-absorbent resin particles is preferably carried out in a stirring and mixing apparatus provided with stirring blades. For example, there is a method in which water (or water in which an inorganic salt is dissolved) is sprayed or dropped while stirring the water-absorbing resin particles supplied into the stirring and mixing device. In spraying or dropping, either a predetermined amount of batch addition or divided addition may be used.
【００１８】攪拌羽根を備えた攪拌混合装置としては、
通常の混合装置でよく、例えば、スクリュー型混合機、
スクリュー型押出機、タービュライザー、ナウター型混
合機、リボン型混合機、双腕型ニーダー、双腕型万能混
合機などが挙げられる。尚、攪拌羽根の形状および数
（単数または複数）については特に限定はない。上記の
ように水を添加して得られたの吸水性樹脂粒子は、その
後の乾燥操作なしに製品化されるのが通常であるが、必
要により含水率調整や粒度調整操作を施してもよい。As a stirring and mixing device provided with stirring blades,
A normal mixing device may be used, for example, a screw type mixer,
Examples thereof include a screw type extruder, a turbulizer, a Nauter type mixer, a ribbon type mixer, a double-arm kneader, and a double-arm universal mixer. The shape and number (single or plural) of the stirring blades are not particularly limited. The water-absorbent resin particles obtained by adding water as described above are usually produced without a drying operation, but may be subjected to a water content adjustment or a particle size adjustment if necessary. .
【００１９】本発明の吸水性樹脂粒子は、表面架橋後か
ら製品化までの任意の段階で、防腐剤、防かび剤、抗菌
剤、酸化防止剤、還元性防止剤、芳香剤、消臭剤、無機
微粉末（シリカ微粉末など）、耐吸湿ブロッキング防止
剤などを添加したものとすることができ、その添加量は
通常５重量％以下である。The water-absorbent resin particles of the present invention can be used at any stage after surface cross-linking until commercialization, as a preservative, a fungicide, an antibacterial agent, an antioxidant, an antioxidant, a fragrance, a deodorant. , An inorganic fine powder (such as a silica fine powder), a moisture-absorbing anti-blocking agent, and the like, and the amount of addition is usually 5% by weight or less.
【００２０】本発明の吸水性樹脂粒子の破断応力は、水
の添加による含水率の調整によってコントロールするこ
とができる。樹脂粒子の含水率は３〜９％、好ましくは
３〜７％であり、後述する方法で測定される粒子の破断
応力は通常３０Ｎ／ｍ2以上、好ましくは３０〜１００
Ｎ／ｍ2である。含水率が３％未満では粒子の破断応力
が低く、粒子の脆さや壊れ性の改善効果に乏しい。一方
９％を越えると貯蔵中あるいは輸送中などにおける荷重
が加わる条件下で粒子同士の凝集が生じやすくなり好ま
しくない。また、粒子の破断応力が３０Ｎ／ｍ2未満の
場合、粒子の機械的強度が不十分となり、脆く壊れやす
い粒子となる。その結果、吸水性樹脂粒子を使用する場
面、例えばスクリューコンベアーやスプリングコンベア
ー等による機械的な輸送あるいは空気圧による輸送の場
面、スクリューフィーダー等で供給・散布したり、空気
圧でスプレー散布する工程において、粒子同士の衝突、
機械や設備の壁面への粒子の衝突、機械的摩擦などによ
って吸水性樹脂粒子が壊れて粒度分布が変化するという
問題を生じる。更に、粒子が壊れることによって表面架
橋の効果を損なって吸収性能やゲル物性が悪化する、粒
子が壊れて微粒子が生成することによって粉塵が発生す
るという問題が発生する。The breaking stress of the water-absorbent resin particles of the present invention can be controlled by adjusting the water content by adding water. The water content of the resin particles is 3 to 9%, preferably 3 to 7%, and the breaking stress of the particles measured by the method described later is usually 30 N / m 2 or more, preferably 30 to 100%.
N / m2. If the water content is less than 3%, the breaking stress of the particles is low, and the effect of improving the brittleness and fragility of the particles is poor. On the other hand, if it exceeds 9%, the particles are likely to aggregate under the condition that a load is applied during storage or transportation, which is not preferable. On the other hand, when the breaking stress of the particles is less than 30 N / m 2, the mechanical strength of the particles becomes insufficient and the particles become brittle and fragile. As a result, when water-absorbing resin particles are used, for example, when mechanically transported by a screw conveyor or a spring conveyor or transported by air pressure, or supplied and sprayed with a screw feeder or the like, or in a process of spraying and spraying with air pressure, Collision between each other,
There is a problem that the water-absorbent resin particles are broken due to collision of particles against a wall of a machine or equipment, mechanical friction, or the like, and the particle size distribution is changed. Further, there is a problem in that the broken particles impair the effect of surface cross-linking to deteriorate absorption performance and gel physical properties, and that the broken particles generate fine particles to generate dust.
【００２１】[0021]
【実施例】以下、実施例および比較例により本発明をさ
らに説明するが、本発明はこれらに限定されるものでは
ない。含水率、粒子の破断応力、微粒子含量、粉塵度お
よび加圧吸収量は下記の方法により測定し、粒子の壊れ
性試験は下記の方法で実施した。以下、特に定めない限
り、％は重量％を示す。The present invention will be further described with reference to the following examples and comparative examples, but the present invention is not limited to these examples. The water content, the breaking stress of the particles, the content of fine particles, the degree of dust, and the amount of pressure absorption were measured by the following methods, and the breaking test of the particles was performed by the following method. Hereinafter, unless otherwise specified,% indicates% by weight.
【００２２】含水率：１００ｍｌビーカーにサンプル５
ｇを入れて平坦に均した後、１０５℃に調整された非循
環型オーブンの中に入れる。２時間乾燥後、室温まで冷
却した後、減少した重量を測定する。この減少重量の乾
燥前サンプル重量に対する比を含水率（単位％）とし
た。Water content: Sample 5 in a 100 ml beaker
After adding g, the mixture is leveled and then placed in a non-circulating oven adjusted to 105 ° C. After drying for 2 hours and cooling to room temperature, the reduced weight is measured. The ratio of the reduced weight to the weight of the sample before drying was defined as the water content (unit%).
【００２３】粒子の破断応力：４００〜５００ミクロン
の粒径のサンプルをクリープメーター（山電株式会社
製）を用いて圧縮試験し、粒子が破断する時の応力値を
求めて破断応力（単位Ｎ／ｃｍ2）とした。Particle rupture stress: A sample having a particle size of 400 to 500 microns is subjected to a compression test using a creep meter (manufactured by Yamaden Co., Ltd.), and the stress value at the time of particle rupture is determined to determine the rupture stress (unit: N). / Cm2).
【００２４】粒子の壊れ性試験：サンプル１００ｇをボ
ールミル（ポール数５個）に入れ、毎分１５０回転で１
５分間回転させる。Particle breakability test: 100 g of a sample was placed in a ball mill (5 poles),
Spin for 5 minutes.
【００２５】微粒子含量：１４０メッシュ（目開き１０
５ミクロン；直径２０ｃｍ）のＪＩＳフルイと受け皿が
セットされたロータップ試験機（飯田製作所製）に、サ
ンプル５０ｇを１４０メッシュフルイの上に載せ、５分
間振動させる（振動数：毎分１６５回）。１４０メッシ
ュを通過した粒子重量の全サンプル重量に対する比を微
粒子含量（単位％）とした。Fine particle content: 140 mesh (opening 10
A 50 g sample is placed on a 140-mesh screen on a low tap tester (manufactured by Iida Seisakusho) equipped with a JIS screen (5 microns; diameter 20 cm) and a tray, and vibrated for 5 minutes (frequency: 165 times per minute). The ratio of the weight of particles passing through the 140 mesh to the total sample weight was defined as the content of fine particles (%).
【００２６】粉塵度：１リットル吸引瓶の吸引口とデジ
タル粉塵計（柴田科学製）の吸入口を内径７ｍｍ、長さ
１０ｃｍのガラス管で接続する。吸引瓶の上部の口か
ら、ロートを用いて吸水性樹脂２０ｇを吸引瓶に落下さ
せる。落下させた吸水性樹脂粉末中の１分間に発生した
粉塵の個数をデジタル粉塵計を用いて測定し、この値を
粉塵度（単位ＣＰＭ）とした。Dust degree: The suction port of a 1-liter suction bottle is connected to the suction port of a digital dust meter (manufactured by Shibata Kagaku) with a glass tube having an inner diameter of 7 mm and a length of 10 cm. 20 g of the water-absorbent resin is dropped into the suction bottle from the upper mouth of the suction bottle using a funnel. The number of dusts generated in one minute in the dropped water-absorbent resin powder was measured using a digital dust meter, and this value was taken as the dust degree (unit: CPM).
【００２７】加圧吸収量：２５０メッシュのナイロン網
を底面に貼った円筒型プラスチックチューブ（内径３０
ｍｍ、高さ６０ｍｍ）内に吸水性樹脂０．１ｇを入れて
平坦に均す。この樹脂の上に２０ｇ／ｃｍ2の荷重とな
るように外径３０ｍｍの分銅を乗せる。生理食塩水６０
ｍｌの入ったシャーレ（直径：１２ｃｍ）の中に吸水性
樹脂の入ったプラスチックチューブをナイロン網側を下
面にして浸し、放置する。吸水性樹脂が生理食塩水を吸
収して増加した重量を６０分後に測定し、この１０倍値
を生理食塩水に対する加圧吸収量（単位ｇ／ｇ）とし
た。Amount of pressure absorption: A cylindrical plastic tube (with an inner diameter of 30) having a nylon mesh of 250 mesh attached to the bottom surface.
(mm, height: 60 mm) and 0.1 g of the water-absorbent resin is put into the resin and leveled. A weight having an outer diameter of 30 mm is placed on the resin so as to have a load of 20 g / cm 2 . Physiological saline 60
A plastic tube containing a water-absorbent resin is immersed in a petri dish (diameter: 12 cm) containing the water-absorbent resin with the nylon mesh side facing down, and left to stand. The weight of the water-absorbent resin increased by absorbing the physiological saline was measured 60 minutes later, and the tenfold value was defined as the pressure absorption amount (unit: g / g) with respect to the physiological saline.
【００２８】製造例１ アクリル酸２００ｇ、架橋剤としてメチレンビスアクリ
ルアミド０.３ｇ、イオン交換水６００ｇを混合して重
合性単量体水溶液を調整し、この混合液を断熱重合可能
な重合槽に投入した。溶液中に窒素ガスを導入すること
により、溶液中の溶存酸素量を０．１ｐｐｍ以下、溶液
温度を５℃とした。この重合溶液に、３５％過酸化水素
水０．０３ｇ、アスコルビン酸０．００５ｇ、Ｖ−５０
（和光純薬工業製アゾ系触媒）０．１ｇを添加した。１
０分後に重合開始を示す温度上昇が確認され、約３時間
後に最高到達温度に達した。更に４時間熟成してゲル状
重合体を得た。 このゲル状重合体６００ｇを小型ニー
ダーを用いて小片に砕断した後、これに５０％のＮａＯ
Ｈ水溶液１２０ｇを添加し、均一に混合した。この中和
されたゲルを熱風乾燥した後、２０〜１４５メッシュの
粒度に粉砕して吸水性樹脂粒子（ａ）を得た。あらかじ
めエチレングリコールジグリシジルエーテル（製品名：
ナガセ化成工業（株）「デナコールＥＸー８１０」）
０．６ｇを、水２５ｇとメタノール１０ｇの混合液に溶
解して表面架橋剤溶液を作成した。吸水性樹脂粒子
（ａ）６０ｇを容量２リットルの家庭用ジュサーミキサ
ーに入れ、高速攪拌しながら上記表面架橋剤溶液３.５
ｇを添加して十分混合した。この混合物を、１４０℃に
調整した熱風乾燥機で６０分間加熱架橋し、表面架橋型
吸水性樹脂粒子（ａ１）を得た。（ａ１）の含水率は
０．８％であった。Production Example 1 200 g of acrylic acid, 0.3 g of methylenebisacrylamide as a cross-linking agent, and 600 g of ion-exchanged water were mixed to prepare an aqueous solution of a polymerizable monomer, and this mixture was put into a polymerization tank capable of adiabatic polymerization. did. By introducing nitrogen gas into the solution, the amount of dissolved oxygen in the solution was set to 0.1 ppm or less, and the solution temperature was set to 5 ° C. To this polymerization solution, 0.03 g of 35% hydrogen peroxide solution, 0.005 g of ascorbic acid, V-50
(Azo-based catalyst manufactured by Wako Pure Chemical Industries) 0.1 g was added. 1
After 0 minute, a temperature rise indicating the start of polymerization was confirmed, and the temperature reached the highest temperature after about 3 hours. After further aging for 4 hours, a gel polymer was obtained. 600 g of this gel polymer was cut into small pieces using a small kneader, and 50% NaO
120 g of H aqueous solution was added and mixed uniformly. The neutralized gel was dried with hot air and then pulverized to a particle size of 20 to 145 mesh to obtain water-absorbent resin particles (a). Ethylene glycol diglycidyl ether (product name:
Nagase Kasei Kogyo Co., Ltd. "Denacol EX-810")
0.6 g was dissolved in a mixed solution of 25 g of water and 10 g of methanol to prepare a surface crosslinking agent solution. 60 g of the water-absorbent resin particles (a) are placed in a household juicer mixer having a capacity of 2 liters, and the above surface crosslinking agent solution 3.5 is stirred at a high speed.
g was added and mixed well. This mixture was heated and crosslinked with a hot air dryer adjusted to 140 ° C. for 60 minutes to obtain surface crosslinked water-absorbent resin particles (a1). The water content of (a1) was 0.8%.
【００２９】製造例２ あらかじめポリアミドポリアミンエピクロルヒドリン樹
脂１．５ｇを、水１０ｇとメチルトリグリコール５ｇの
混合液に溶解して表面架橋剤溶液を作成した。吸水性樹
脂粒子（ａ）１２０ｇを高速撹拌しながら上記表面架橋
剤溶液３ｇを添加して十分混合した。この混合物を、１
３０℃に調整した熱風乾燥機で４５分間加熱し、表面架
橋型吸水性樹脂粒子（ａ２）を得た。（ａ２）の含水率
は１．２％であった。Production Example 2 A surface crosslinking agent solution was prepared by previously dissolving 1.5 g of a polyamide polyamine epichlorohydrin resin in a mixture of 10 g of water and 5 g of methyltriglycol. While stirring 120 g of the water-absorbent resin particles (a) at a high speed, 3 g of the above surface crosslinking agent solution was added and mixed well. This mixture is
The mixture was heated for 45 minutes with a hot-air dryer adjusted to 30 ° C. to obtain surface-crosslinked water-absorbent resin particles (a2). The water content of (a2) was 1.2%.
【００３０】参考例１ 吸水性樹脂粒子（ａ１）１００ｇを容量２リットルの家
庭用ジュサーミキサーに入れ、高速撹拌しながら水道水
４ｇを添加して十分混合することにより本発明の吸水性
樹脂粒子（イ）を得た。混合中に凝集塊の生成は見られ
なかった。得られた吸水性樹脂粒子（イ）の含水率は
４．４％であった。粒子の破断応力、および壊れ性試験
前の微粒子含量、粉塵度、加圧吸収量の測定結果を表１
に、壊れ性試験後の微粒子含量、粉塵度、加圧吸収量の
測定結果を表２に示す。REFERENCE EXAMPLE 1 100 g of the water-absorbent resin particles (a1) were placed in a household juicer mixer having a capacity of 2 liters, and 4 g of tap water was added with high-speed stirring and thoroughly mixed, whereby the water-absorbent resin particles of the present invention were obtained. (B) was obtained. No agglomerates were formed during mixing. The water content of the resulting water-absorbent resin particles (a) was 4.4%. Table 1 shows the measurement results of the breaking stress of the particles, the content of fine particles before the fragility test, the degree of dust, and the amount of pressure absorption.
Table 2 shows the measurement results of the content of fine particles, the degree of dust, and the amount of pressure absorption after the fragility test.
【００３１】実施例１ 吸水性樹脂粒子（ａ１）１００ｇを容量２リットルの家
庭用ジュサーミキサーに入れ、高速撹拌しながらナトリ
ウム明礬２０％水溶液６ｇを添加して十分混合すること
により本発明の吸水性樹脂粒子（ロ）を得た。混合中に
凝集塊の生成は見られなかった。得られた吸水性樹脂粒
子（ロ）の含水率は５．２％であった。粒子の破断応力
および壊れ性試験前の微粒子含量、粉塵度、加圧吸収量
の測定結果を表１に、壊れ性試験後の微粒子含量、粉塵
度、加圧吸収量の測定結果を表２に示す。Example 1 100 g of the water-absorbing resin particles (a1) were placed in a household juicer mixer having a capacity of 2 liters, and 6 g of a 20% aqueous solution of sodium alum was added thereto while stirring at a high speed. Resin particles (b) were obtained. No agglomerates were formed during mixing. The water content of the resulting water-absorbent resin particles (b) was 5.2%. Table 1 shows the measurement results of the fracture stress of the particles and the fine particle content, dustiness, and pressure absorption before the fragility test, and Table 2 the measurement results of the fine particle content, dustiness, and pressure absorption after the friability test. Show.
【００３２】実施例２ 実施例１において、ナトリウム明礬２０％水溶液の添加
量を３．５ｇとする以外は実施例２と同様にして本発明
の吸水性樹脂粒子（ハ）を得た。混合中に凝集塊の生成
は見られなかった。得られた吸水性樹脂粒子（ハ）の含
水率は３．３％であった。粒子の破断応力および壊れ性
試験前の微粒子含量、粉塵度、加圧吸収量の測定結果を
表１に、壊れ性試験後の微粒子含量、粉塵度、加圧吸収
量の測定結果を表２に示す。Example 2 Water-absorbent resin particles (c) of the present invention were obtained in the same manner as in Example 1 except that the amount of the 20% aqueous sodium alum solution was changed to 3.5 g. No agglomerates were formed during mixing. The water content of the obtained water-absorbent resin particles (c) was 3.3%. Table 1 shows the measurement results of the fracture stress of the particles and the fine particle content, dustiness, and pressure absorption before the fragility test, and Table 2 the measurement results of the fine particle content, dustiness, and pressure absorption after the friability test. Show.
【００３３】実施例３ 実施例１において、ナトリウム明礬２０％水溶液６ｇに
代えて、硫酸ナトリウム２０％水溶液を同量使用する以
外は実施例２と同様にして本発明の吸水性樹脂粒子
（ニ）を得た。混合中に凝集塊の生成は見られなかっ
た。得られた吸水性樹脂粒子（ニ）の含水率は５．３％
であった。粒子の破断応力および壊れ性試験前の微粒子
含量、粉塵度、加圧吸収量の測定結果を表１に、壊れ性
試験後の微粒子含量、粉塵度、加圧吸収量の測定結果を
表２に示す。Example 3 The water-absorbent resin particles of the present invention (d) were prepared in the same manner as in Example 1 except that the same amount of a 20% aqueous sodium sulfate solution was used instead of 6 g of a 20% aqueous sodium alum solution. I got No agglomerates were formed during mixing. The water content of the obtained water-absorbent resin particles (d) is 5.3%.
Met. Table 1 shows the measurement results of the fracture stress of the particles and the fine particle content, dustiness, and pressure absorption before the fragility test, and Table 2 the measurement results of the fine particle content, dustiness, and pressure absorption after the friability test. Show.
【００３４】実施例４ 実施例１の吸水性樹脂粒子（ａ１）に代えて、吸水性樹
脂粒子（ａ２）を使用する以外は実施例１と同様にして
本発明の吸水性樹脂粒子（ホ）を得た。混合中に凝集塊
の生成は見られなかった。得られた吸水性樹脂粒子
（ホ）の含水率は５．６％であった。粒子の破断応力お
よび壊れ性試験前の微粒子含量、粉塵度、加圧吸収量の
測定結果を表１に、壊れ性試験後の微粒子含量、粉塵
度、加圧吸収量の測定結果を表２に示す。Example 4 The water-absorbent resin particles (e) of the present invention were prepared in the same manner as in Example 1 except that the water-absorbent resin particles (a1) were replaced with the water-absorbent resin particles (a2). I got No agglomerates were formed during mixing. The water content of the obtained water-absorbent resin particles (e) was 5.6%. Table 1 shows the measurement results of the fracture stress of the particles and the fine particle content, dustiness, and pressure absorption before the fragility test, and Table 2 the measurement results of the fine particle content, dustiness, and pressure absorption after the friability test. Show.
【００３５】比較例１および２ 吸水性樹脂粒子（ａ１）および（ａ２）を比較の吸水性
樹脂粒子とし、粒子の破断応力および壊れ性試験前の微
粒子含量、粉塵度、加圧吸収量の測定結果を表１に、壊
れ性試験後の微粒子含量、粉塵度、加圧吸収量の測定結
果を表２に示す。Comparative Examples 1 and 2 The water-absorbing resin particles (a1) and (a2) were used as comparative water-absorbing resin particles, and the breaking stress of the particles and the fine particle content, dustiness and pressure absorption before the breaking test were measured. Table 1 shows the results, and Table 2 shows the measurement results of the fine particle content, dustiness, and pressure absorption after the fragility test.
【００３６】比較例３ 製造例１で得られた吸水性樹脂粒子（ａ）６０ｇを容量
２リットルの家庭用ジュサーミキサーに入れ、高速攪拌
しながら、あらかじめエチレングリコールジグリシジル
エーテル０．６ｇを、水２５ｇとメタノール１０ｇの混
合液に溶解して作成した表面架橋剤溶液３.５ｇを添加
して十分混合した。この混合物を、１００℃に調整した
熱風乾燥機で６０分間加熱し、比較の表面架橋型吸水性
樹脂粒子（ａ３）を得た。（ａ３）の含水率は１．９％
であった。粒子の破断応力および壊れ性試験前の微粒子
含量、粉塵度、加圧吸収量の測定結果を表１に、壊れ性
試験後の微粒子含量、粉塵度、加圧吸収量の測定結果を
表２に示す。Comparative Example 3 60 g of the water-absorbent resin particles (a) obtained in Production Example 1 were placed in a household juicer mixer having a capacity of 2 liters, and while stirring at a high speed, 0.6 g of ethylene glycol diglycidyl ether was added thereto in advance. 3.5 g of a surface crosslinking agent solution prepared by dissolving in a mixed solution of 25 g of water and 10 g of methanol was added and mixed well. This mixture was heated for 60 minutes with a hot air drier adjusted to 100 ° C. to obtain comparative surface crosslinked type water-absorbent resin particles (a3). The water content of (a3) is 1.9%
Met. Table 1 shows the measurement results of the fracture stress of the particles and the fine particle content, dustiness, and pressure absorption before the fragility test, and Table 2 the measurement results of the fine particle content, dustiness, and pressure absorption after the friability test. Show.
【００３７】[0037]
【表１】 ＜壊れ性試験前の性能＞ −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− ｜ ｜含水率｜粒子の破断応力｜微粒子含量｜ 粉塵度 ｜加圧吸収量｜ ｜ ｜（％）｜ （Ｎ／ｍ２） ｜ (％） ｜ （cpm）｜（ｇ／ｇ）｜ ｜−−−−｜−−−｜−−−−−−−｜−−−−−｜−−−−｜−−−−−｜ ｜参考例１｜４．４｜ ６１ ｜ ０．６ ｜ ８ ｜ ３４ ｜ ｜−−−−｜−−−｜−−−−−−−｜−−−−−｜−−−−｜−−−−−｜ ｜実施例１｜５．２｜ ６８ ｜ ０．３ ｜ ５ ｜ ３４ ｜ ｜−−−−｜−−−｜−−−−−−−｜−−−−−｜−−−−｜−−−−−｜ ｜実施例２｜３．３｜ ５３ ｜ ０．５ ｜ ９ ｜ ３５ ｜ ｜−−−−｜−−−｜−−−−−−−｜−−−−−｜−−−−｜−−−−−｜ ｜実施例３｜５．３｜ ７０ ｜ ０．４ ｜ ６ ｜ ３４ ｜ ｜−−−−｜−−−｜−−−−−−−｜−−−−−｜−−−−｜−−−−−｜ ｜実施例４｜５．６｜ ７３ ｜ ０．４ ｜ ４ ｜ ３３ ｜ ｜−−−−｜−−−｜−−−−−−−｜−−−−−｜−−−−｜−−−−−｜ ｜比較例１｜０．８｜ １９ ｜ ０．５ ｜ １５ ｜ ３６ ｜ ｜−−−−｜−−−｜−−−−−−−｜−−−−−｜−−−−｜−−−−−｜ ｜比較例２｜１．２｜ ２２ ｜ ０．６ ｜ １７ ｜ ３５ ｜ ｜−−−−｜−−−｜−−−−−−−｜−−−−−｜−−−−｜−−−−−｜ ｜比較例３｜１．９｜ ２５ ｜ ０．５ ｜ １８ ｜ ３５ ｜ −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−<Table 1> <Performance before fragility test> --------------------------------------------------------------------------- || Moisture content | Breaking stress of particles | Fine particle content | Dust degree | Absorption under pressure | | | (%) | (N / m2) | (%) | −− | −−−−−−− | −−−−− | −−−− | −−−−− || Reference Example 1 | 4.4 | 61 | 0.6 | 8 | 34 || −−−−− | −−−−−− | −−−−− | −−−− | −−−−− || Example 1 | 5.2 | 68 | 0.3 | 5 | 34 │ │ │ │ │ │ │ │ │ │ │ │ │ │ 0.5 │ 0.5 │ 0.5 │ 0.5 │ 9 │ 35 │ │ −−−− | −−− | −−−−−−− | −−−−− | −−−− | −−−−− || Example 3 | 5 0.3 | 70 | 0.4 | 6 | 34 | |-----------------------------| Example 4 | 5.6 | 73 | 0.4 | 4 | 33 | | ----| --- |--------------------------------- 19 | 0.5 | 15 | 36 | |-----------------------------| −−−−− | | Comparative Example 2 | 1.2 | 22 | 0.6 | 17 | 35 || -------------------- | ---- | -------------------- −−− | −−−−− || Comparative Example 3 | 1.9 | 25 | 0.5 | 18 | 35 | −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− | −−−−−−−−−−−−−−−
【００３８】[0038]
【表２】 [Table 2]
【００３９】表１および表２の結果から、実施例１〜４
で得られた本発明の吸水性樹脂粒子（イ）〜（ホ）は、
比較例１〜３の比較の吸水性樹脂粒子（ａ１）〜（ａ
３）に比らべて粒子の破断応力が大きく、壊れ性試験後
においても微粒子含量の増加および粉塵度の増加が少な
く、加圧吸収量の低下もないことから、飛躍的な改善が
認められる。From the results in Tables 1 and 2, Examples 1 to 4
The water-absorbent resin particles (A) to (E) of the present invention obtained in
Comparative water-absorbent resin particles (a1) to (a) of Comparative Examples 1 to 3.
Compared with 3), the breaking stress of the particles is large, and even after the breakability test, there is little increase in the content of fine particles and the degree of dust, and there is no decrease in the amount of pressure absorption. .
【００４０】[0040]
【発明の効果】本発明の方法、および本発明の方法によ
り得られる本発明の吸水性樹脂粒子はは次のような効果
を奏する。 本発明の方法は、加熱表面架橋後に水を添加するとい
う簡単な操作で吸水性樹脂粒子の粉体物性（粒子の破断
応力）を改質することができる。 粒子の破断応力がアップする結果、機械的剪断力に対
する壊れ性、粒子脆さの改善された吸水性樹脂粒子が製
造できる。 その結果、吸水性樹脂粒子を使用する場面、例えばス
クリューコンベアーやスプリングコンベアー等による機
械的な輸送あるいは空気圧による輸送の場面、スクリュ
ーフィーダー等で供給・散布したり、空気圧でスプレー
散布する工程において、粒子同士の衝突、機械や設備の
壁面への粒子の衝突、機械的摩擦などによる粒度分布の
変化が少ない。 機械的剪断力が加わっても粒子の壊れによる微粒子の
生成が少なく、粉塵発生がほとんどないことから、作業
環境を悪化させる心配や、粉塵吸入の心配が無いことか
ら作業者に安全である。。 更に、粒子の壊れによって表面架橋の効果を損なうこ
とによる、吸収性能やゲル物性の悪化がない。 上記のことから、ドラムフォーミング方式で紙おむつ
を製造する場合に特に有用であり、パルプ／吸水性樹脂
粒子積層用のスクリーンメッシュやパンチングプレート
への吸水性樹脂粒子の目詰まりが少なくなる。The method of the present invention and the water-absorbent resin particles of the present invention obtained by the method of the present invention have the following effects. The method of the present invention can improve the powder physical properties (rupture stress of the particles) of the water-absorbent resin particles by a simple operation of adding water after the heat surface crosslinking. As a result of increasing the breaking stress of the particles, water-absorbent resin particles having improved fragility against mechanical shearing force and improved particle brittleness can be produced. As a result, when water-absorbing resin particles are used, for example, when mechanically transported by a screw conveyor or a spring conveyor or transported by air pressure, or supplied and sprayed with a screw feeder or the like, or in a process of spraying and spraying with air pressure, There is little change in particle size distribution due to collision between particles, collision of particles on the wall of a machine or equipment, and mechanical friction. Even if a mechanical shearing force is applied, the generation of fine particles due to the breakage of the particles is small, and there is almost no generation of dust. Therefore, it is safe for the worker because there is no fear of deteriorating the working environment or worry of sucking dust. . Further, there is no deterioration in absorption performance or gel properties due to impairment of surface crosslinking effect due to breakage of particles. From the above, the present invention is particularly useful when producing a disposable diaper by a drum forming method, and the clogging of the screen mesh or the punching plate for laminating pulp / water-absorbent resin particles with the water-absorbent resin particles is reduced.
【００４１】上記効果を奏することから、本発明の方法
により得られる本発明の吸水性樹脂粒子は、吸水性樹脂
粒子の輸送、供給、散布を伴うあらゆる場面に有用であ
る。特に吸水性樹脂粒子を多量に取り扱う吸収性当材、
衛生材料（子供用および大人用紙おむつ、生理用ナプキ
ン、失禁用パッド等）等の製造に有用であり、性能の優
れた製品が得られる。Due to the above-mentioned effects, the water-absorbent resin particles of the present invention obtained by the method of the present invention are useful in all occasions involving transportation, supply and dispersion of water-absorbent resin particles. Absorbent material that handles a large amount of water-absorbent resin particles,
It is useful for the manufacture of sanitary materials (child and adult disposable diapers, sanitary napkins, incontinence pads, etc.) and provides products with excellent performance.
───────────────────────────────────────────────────── フロントページの続き 審査官 佐々木 秀次 (56)参考文献 特開 平５−31362（ＪＰ，Ａ) 特開 昭62−7745（ＪＰ，Ａ) 特公 平７−62073（ＪＰ，Ｂ２) 米国特許4734478（ＵＳ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C08L 33/02 C08F 6/00 C08J 3/12 - 3/24 ────────────────────────────────────────────────── ─── Continuation of the front page Examiner Hideji Sasaki (56) References JP-A-5-31362 (JP, A) JP-A-62-27745 (JP, A) JP-B 7-62073 (JP, B2) United States Patent 4734478 (US, A) (58) Fields investigated (Int. Cl. 7 , DB name) C08L 33/02 C08F 6/00 C08J 3/12-3/24
Claims (8)
を主構成単位とし、且つ該アクリル酸および／またはア
クリル酸塩と反応しうる官能基を２個以上有する架橋剤
で粒子表面近傍が加熱架橋された吸水性樹脂粒子に、加
熱架橋後に水に対する濃度が５〜５０重量％である無機
の塩を溶解している水および／または無機の水酸化物を
溶解している水を添加して含水率を３〜９％に調整する
ことを特徴とする粒子脆さの改質された吸水性樹脂粒子
の製法。1. A cross-linking agent having acrylic acid and / or acrylate as a main constituent unit and having at least two functional groups capable of reacting with said acrylic acid and / or acrylate is heated and crosslinked in the vicinity of the particle surface. To the water-absorbent resin particles, water containing an inorganic salt and / or water dissolving an inorganic hydroxide having a concentration with respect to water of 5 to 50% by weight after heat crosslinking is added. Is adjusted to 3 to 9%, the method for producing water-absorbent resin particles having improved particle brittleness.
量に対して２〜１５重量％である請求項１記載の方法。2. The method according to claim 1, wherein the amount of water to be added is 2 to 15% by weight based on the weight of the water-absorbent resin particles.
リ土類金属塩、アルミニウム塩から選ばれる少なくとも
１種である請求項１または２記載の製法。3. The method according to claim 1, wherein the inorganic salt is at least one selected from an alkali metal salt, an alkaline earth metal salt, and an aluminum salt.
項１〜３の何れか記載の製法。4. The method according to claim 1, wherein the inorganic salt is an alkali metal salt.
塩と反応しうる官能基を２個以上有する架橋剤が、ポリ
グリシジルエーテル系化合物、多価アルコール系化合
物、ポリアミン系化合物およびポリアミン系樹脂から選
ばれるものである請求項１〜４の何れか記載の製法。5. The crosslinking agent having two or more functional groups capable of reacting with acrylic acid and / or acrylate is selected from polyglycidyl ether compounds, polyhydric alcohol compounds, polyamine compounds and polyamine resins. The method according to any one of claims 1 to 4, wherein the method is performed.
根を備えた撹拌混合装置内でおこなう請求項１〜５の何
れか記載の製法。6. The method according to claim 1, wherein the water is added to the water-absorbent resin particles in a stirring and mixing device provided with stirring blades.
が３０Ｎ／ｍ2以上である請求項１〜６の何れか記載の
製法。7. The method according to claim 1, wherein the modified water-absorbent resin particles have a breaking stress of 30 N / m 2 or more.
を主構成単位とし、且つ該アクリル酸および／またはア
クリル酸塩と反応しうる官能基を２個以上有する架橋剤
で粒子表面近傍が加熱架橋された吸水性樹脂粒子に、水
に対する濃度が５〜５０重量％である無機の塩を溶解し
ている水および／または無機の水酸化物を溶解している
水を添加して得られる、含水率が３〜９％であり、粒子
の破断応力が３０Ｎ／ｍ2以上である粒子脆さの改質さ
れた吸水性樹脂粒子。8. A cross-linking agent having acrylic acid and / or acrylate as a main constituent unit and having at least two functional groups capable of reacting with said acrylic acid and / or acrylate is heated and crosslinked in the vicinity of the particle surface. Water content obtained by adding water dissolving an inorganic salt and / or water dissolving an inorganic hydroxide to the water-absorbent resin particles, the concentration of which is 5 to 50% by weight based on water. Is 3 to 9%, and the particle embrittlement is 30 N / m 2 or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07308276A JP3103754B2 (en) | 1995-10-31 | 1995-10-31 | Modified water-absorbing resin particles and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07308276A JP3103754B2 (en) | 1995-10-31 | 1995-10-31 | Modified water-absorbing resin particles and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09124879A JPH09124879A (en) | 1997-05-13 |
| JP3103754B2 true JP3103754B2 (en) | 2000-10-30 |
Family
ID=17979085
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP07308276A Expired - Fee Related JP3103754B2 (en) | 1995-10-31 | 1995-10-31 | Modified water-absorbing resin particles and method for producing the same |
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| Country | Link |
|---|---|
| JP (1) | JP3103754B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007510804A (en) * | 2003-11-12 | 2007-04-26 | ストックハウゼン・インコーポレイテッド | Superabsorbent polymer with delayed free water absorption |
| WO2011040472A1 (en) | 2009-09-29 | 2011-04-07 | 株式会社日本触媒 | Particulate water absorbent and process for production thereof |
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