JPH0116768B2

JPH0116768B2 -

Info

Publication number: JPH0116768B2
Application number: JP54022004A
Authority: JP
Inventors: Yoshiaki Koga
Original assignee: Tokuyama Corp
Current assignee: Tokuyama Corp
Priority date: 1979-02-28
Filing date: 1979-02-28
Publication date: 1989-03-27
Also published as: JPS55116613A

Description

【発明の詳細な説明】[Detailed description of the invention]

本発明は新規な水和珪酸及びその製造方法を提
供するものである。本発明の水和珪酸は特に農薬
担体及びゴム充填剤として優れた性質を有するば
かりでなく、従来公知の水和珪酸の使用分野にも
好適に使用出来るすぐれた水和珪酸である。また
本発明の水和珪酸の製造方法は工業的に簡単な技
術で優れた性状を付与出来るものである。水和珪酸は種々の方法で製造され、種々の用途
に使用されている。例えば合成ゴム充填剤、合成
樹脂充填剤、農薬担持担体、歯科用充填剤等の用
途がある。従来、上記用途に用いる水和珪酸の性質は、そ
の吸油量を増大させることによつて改善されて来
た。しかしながら、単に吸油量を増大させた水和
珪酸は必ずしも前記用途に要求される性質を満足
するものではない。即ち、従来の方法で製造され
る水和珪酸は一般に吸油速度が遅く又吸着された
物質の担持能力、即ち吸着力が弱いという欠点を
有している。そのため例えば、上記水和珪酸を農
薬用担体として用い農薬を製造する場合、農薬成
分を吸着させるのに多くの時間を要し作業性の低
下を招く。また、農薬成分を吸着した水和珪酸を
粉砕、或いは他の添加剤と混合する際、吸着され
た農薬成分が浸出し該農薬成分をバインダーとし
て粉砕機、或いは混合機に水和珪酸及び他の添加
剤などが付着し上記装置のトラブルの原因とな
る。更に、従来の方法で得られる水和珪酸は粒子
径10〜50ｍμの単粒子が凝集してなる凝集粒子径
が小さい微粉状であるため、取扱い時粉塵が発生
し易く、作業性の低下、及び水和珪酸の損失を招
く。また、上記農薬用担体として使用する場合、
添加される農薬成分の捕捉力が弱く、水和珪酸と
農薬成分を混合する混合機の羽根や壁に農薬成分
が付着し、混合機のトラブルの原因となる。本発明者は長年水和珪酸の製造研究を続けて来
た。更に水和珪酸の反応条件、経時変化など多方
面に渡つてその性状を追求して来た結果、意外に
も特定な細孔径分布及び凝集粒子径を有する水和
珪酸が前述した従来の水和珪酸の欠点を全て解消
し多方面の用途に安定した性状を呈することを見
出し本発明を完成させ提案するに至つた。即ち本発明は細孔径分布のうち細孔半径150Å
以下の細孔が占める容積（以下、細孔容積と称す
る）が0.5c.c.／ｇ以上で且つ、粒子径が149μ〜
500μのものを45％以上含む水和珪酸である。ま
た、本発明は珪酸アルカリ水溶液に酸を多段添加
して水和珪酸を製造するに際し全酸添加量に対す
る第１段の酸添加割合(A)が20〜50％、第２段の酸
を添加する時の溶液中のシリカ濃度(C)が２〜６
ｇ／100c.c.、及び反応温度（Ｔ）が70〜100℃の範
囲内で且つで表わされるＸの値が1.28〜1.55となる条件で反
応を行ない上記反応後の液を過して水和珪酸の
湿潤ケークを得、該湿潤ケークに剪断力又は振動
を与えてスラリーとした後、噴霧乾燥することを
特徴とする細孔径分布のうち細孔半径150Å以下
の細孔が占める容積が0.5c.c.／ｇ以上で且つ粒子
径が149μ〜500μのものを45％以上含む水和珪酸
の製造方法を提供するものである。前記した如く水和珪酸は製造方法の違いなどの
差異によつて種々の種類のものが得られる。ま
た、水和珪酸の吸油量も必要に応じて大きくする
ことが可能である。しかしながら、吸油量が大き
い水和珪酸であつても前記した如く種々の用途に
要求される性質を満足することは稀である。即ち、従来の吸油量が大きい水和珪酸であつて
も、吸油速度、吸着力等の性質はほとんど改善さ
れていない。本発明においては、種々の統計的な
実験を重ねた結果、上記性質は水和珪酸の細孔容
積によつて決定されることを確認した。尚、本発明でいう細孔径分布は特に言及しない
限り、水銀ポロシメータ法によつて測定したもの
をいう。水和珪酸の細孔径分布のうち細孔半径150Å以
下の細孔は小さい程吸油速度、吸着力等の性質に
大きな影響を与えるが、極端に小さい細孔例えば
細孔半径50Å以下になると前記吸油速度、吸油力
等の性質にさほど大きな影響を与えない。従つて
本発明において、細孔容積は細孔径分布のうち細
孔半径50〜150Åの細孔が占める容積が特に重要
である。本発明の水和珪酸は上記細孔容積を0.5c.c.／ｇ
以上有することが必要である。細孔容積が0.5
c.c.／ｇより小さいと水和珪酸の吸油速度、吸着力
等の性質はほとんど改善されない。逆に細孔容積
は大きい程上記性質は向上するが、水和珪酸の製
造上技術的な困難を伴なう。従つて本発明におけ
る水和珪酸の細孔容積は0.5〜2.0c.c.／ｇ、特に0.7
〜2.0c.c.／ｇの範囲から選ぶのが好ましい。本発明の如く細孔容積が0.5c.c.／ｇ以上である
水和珪酸は、従来公知の水和珪酸にはほとんど見
い出すことができない。因に、市販されている水
和珪酸の細孔容積は一般に0.11〜0.45c.c.／ｇ程度
である。本発明の水和珪酸は、細孔容積が0.5c.c.／ｇ以
上であれば、全吸油量については特に限定されな
い。一般に吸油量は大きい程好ましく、通常1.5
〜3.5c.c.／ｇ、特に1.8〜3.5c.c.／ｇの範囲のものが
好適である。本発明の水和珪酸においては、更に単粒子が凝
集してなる凝集粒子のうち、粒子径が149μ〜
500μのものを45％以上含んでいることが重要で
ある。該粒子径が上記範囲より小さいものが増加する
と、水和珪酸の取扱い時粉塵が発生し易く、作業
性の低下及び装置のトラブルの原因となるばかり
でなく、例えば農薬用担体として使用した場合に
は混合される農薬成分の捕捉力が弱い。また、該粒子径が上記範囲より大きいものが増
加すると、例えば、農薬用担体として使用した場
合には水和珪酸の内部まで農薬成分が浸透するの
に時間がかかり、作業性の低下を招く。また、
種々の充填剤とした場合、分散性が悪く再粉砕を
必要とするので好ましくない。本発明において、前記範囲の粒子径を有するも
のを45％以上含んでいれば充分であるが、粒子径
が前記範囲外の粒子の粒子径も前記範囲の粒子径
に近づけることが好ましい。本発明の水和珪酸の見掛比重は0.16〜0.24ｇ／
cm³の範囲のものが好適である。尚、前記粒子径は
JIS K1474に準じて測定した値である。本発明の水和珪酸は前記細孔容積、及び粒子径
の２つの条件を満足することによつて始めて効果
を発揮する。本発明の水和珪酸の製造方法は特に
限定されるものではなく、前記２つの条件を満足
するものが得られる限り如何なる製造方法であつ
てもよい。以下本発明の水和珪酸の代表的な製造方法を例
示する。例えば、珪酸アルカリ水溶液に酸を多段
添加して反応させた後、過及び乾燥して水和珪
酸を製造するに際し、全酸添加量に対する第１段
の酸添加割合(A)が20〜50％、第２段の酸を添加す
る時のシリカ濃度(C)が２〜６ｇ／100c.c.、及び反
応温度（Ｔ）が70〜100℃の範囲内で且つで表わされるＸの値が1.28〜1.55となる条件で反
応を行ない、上記反応後の液を過して水和珪酸
の湿潤ケークを得、該湿潤ケークに剪断力又は振
動を与えてスラリーとした後、噴霧乾燥する水和
珪酸の製造方法が好適である。上記製造方法において、珪酸アルカリとしては
珪酸ナトリウム、珪酸カリウム、珪酸アンモニウ
ムなどが一般に用いられる。該珪酸アルカリはモ
ル比（M₂O／SiO₂；ＭはNa、Ｋ、NH₄などを示
す）は特に限定されるものではないが、一般に
2.0〜4.0のものが好適に使用される。また、酸と
しては、硫酸、塩酸、硝酸、燐酸などの鉱酸、炭
酸ガス、亜硫酸ガスなどの酸性ガスが一般に用い
られる。本発明の目的とする水和珪酸を得るためには上
記した珪酸アルカリ水溶液と酸との反応を、珪酸
アルカリ水溶液に酸を多段で添加して行なわせる
ことが好適である。即ちまず珪酸アルカリ水溶液
に第１段の酸添加を行なう。該第１段の酸添加割
合(A)は、全珪酸アルカリを中和するのに必要な酸
の20〜50％とすることが好ましい。第１段の酸添
加割合が上記範囲より低いと、生成する水和珪酸
の単粒子が大きくなり該単粒子が凝集して得られ
る水和珪酸の細孔径が大きくなる傾向がある。従
つて得られる水和珪酸は、吸油量が増大しても細
孔容積を増大させることはできない場合もある。
また、第１段の酸添加割合が上記範囲より高い
と、ゲル化し易く、得られる水和珪酸の細孔容積
が著しく減少するため、吸油速度、及び吸着力等
の性質が改善された水和珪酸を得ることが出来に
くくなる。第１段の酸添加における温度は特に限定されな
いが、一般に10〜65℃程度とすることが得られる
水和珪酸の細孔容積を増加するために好ましい。上記第１段の酸添加の際、極部的な反応を防ぎ
ゲル化を防止するため、一般に適当な撹拌を行う
のが好適な態様となる。第１段の酸添加が終了したら撹拌を継続しなが
ら温度を反応温度に保ち、水和珪酸の種子を析出
させるのが好ましい。反応温度（Ｔ）は70〜100
℃の範囲より選ぶことが最も好適である。反応温
度が上記範囲より低いとゲル化し易く、得られる
水和珪酸の細孔容積が著しく減少するため吸油速
度及び吸着力等の性質が改善された水和珪酸を得
ることができない場合もある。また、反応温度が
上記範囲より高いと、反応中水の蒸発量が増すた
め、反応系のシリカ濃度が変動し、安定した反応
を行なうことができない場合もある。従つて上記
反応において、前記第１段の酸添加を上記反応温
度より低い温度、例えば10〜65℃で行なつた後、
昇温して反応温度に保ち水和珪酸を析出させる態
様は、細孔容積の多い水和珪酸を得る点で好まし
い。第１段の酸添加終了後、第２段の酸を添加する
に際し、溶液中のシリカ濃度(C)は２〜６ｇ／100
c.c.になるように原料の珪酸アルカリの濃度を調整
されていることが好ましい。また該シリカ濃度(C)
は原料珪酸アルカリ水溶液中のシリカの重量を全
溶液の容積で除することによつて知ることができ
る。更に上記シリカ濃度(C)は原料の珪酸アルカリ
水溶液の濃度及びモル比、添加する水の量、第１
段で添加する酸に同伴する水の量、或いは前記反
応温度に保つために水蒸気を溶液中に吹き込んで
加熱を行なう場合、該水蒸気の凝縮水量等によつ
て異なるので、これらの条件を選択することによ
つて調整することができる。第２段の酸を添加するに際し、溶液中のシリカ
濃度(C)が前記範囲より低いと、得られる水和珪酸
の細孔容積は多少増加するが反応系の水の量が多
くなり設備の大型化を招くので工業的に必ずしも
有利とは云えない。しかも、加熱、過等に多大
のエネルギーを要し経済的に不利となる場合が多
い。また、該シリカ濃度が前記範囲より高いとゲ
ル化し易く、得られる水和珪酸の細孔容積が著し
く減少するため、吸油速度、及び吸着力等の性質
が改善された水和珪酸を得ることができない場合
がある。第１段の酸添加後、第２段の酸添加開始は、第
１段の酸添加終了後、水和珪酸の種子の析出によ
つて溶液の粘度が最大となる時期から行なうこと
が好ましい。上記酸添加開始時期は第１段の酸添
加温度、第１段の酸の添加割合、反応温度などの
条件によつて多少異なるが、第１段の酸添加が終
了して25〜40分後である場合が一般的である。第１段の酸添加終了後残部の酸の添加は、前記
反応温度に保ち、連続的或いは多段に分けて行な
うとよい。本方法にあつては、更に、前述した第２段の酸
を添加する時の溶液中のシリカ濃度(C)、全酸添加
量に対する第１段の酸添加割合(A)、及び反応温度
（Ｔ）を関数とする式で表わされるＸの値（以下、Ｘ値と称する）が
1.28〜1.55の範囲内となる如く反応を行なうこと
が好適である。Ｘ値が上記範囲より低いと水和珪
酸の単粒子が大きくなり、該単粒子が凝集して得
られる水和珪酸の細孔径が全体的に大きくなるた
め目的とする水和珪酸を得ることができない場合
もある。また、Ｘ値が上記範囲より高いとゲル化
が起こり易く、細孔容積が著しく減少するため、
吸油速度及び吸着力等の性質が改善された水和珪
酸を得ることができない場合もある。本方法において、他の条件、例えば反応中にア
ルカリ金属塩、アルカリ土類金属塩等の電解質を
添加すること、及び反応終了後得られる水和珪酸
スラリーに水熱処理などの後処理を行なうことな
どは必要に応じて適宜実施することができる。前記方法によつて得られた水和珪酸スラリー
は、公知の装置を用いて過される。例えば、一
般にフイルタープレス型、回転型等の過機を用
いて過すればよい。上記過によつて得られる水和珪酸は湿潤ケー
クとして分離される。該湿潤ケークは剪断力又は
振動を与えることにより簡単にスラリー化する。
従つて該湿潤ケークを一旦スラリーとした後、噴
霧乾燥すると粒子径149μ〜500μのものを45％以
上含む水和珪酸を得ることが出来る。前述した反応条件によつて、単粒子径が小さい
水和珪酸を得ることができ、該単粒子が凝集した
細孔容積の大きい水和珪酸製品を得ることができ
る。しかしながら、前記過によつて得られる水
和珪酸の湿潤ケークを単に乾燥しただけでは本発
明の目的とする粒子径を有する水和珪酸を得るこ
とは一般にできない。即ち、水和珪酸を湿潤ケー
クの状態で乾燥すると単粒子の凝集が過度に起こ
る。そのため、乾燥後粉砕する必要があり、工程
が複雑化するばかりでなく粉砕の際粒子径を制御
することは非常に困難である。前記方法にあつて
は、水和珪酸の有するチクソトロピー性を利用し
て、過によつて得られる水和珪酸の湿潤ケーク
に剪断力又は振動を与え、単粒子の凝集を一旦切
断してスラリーとした後、噴霧乾燥することによ
り前記粒子径を有する水和珪酸を容易に得ること
が出来るので工業的に有利である。前記過によつて得られる水和珪酸の湿潤ケー
クは一般に含有水分量40〜90特に50〜85（重量）
％の流動性を有しない固形物として得られるが、
これに適当な剪断力、又は振動を与えると単粒子
の凝集が切断されると共に、凝集粒子間に含まれ
ている水分が分離されて次第に流動性をおびスラ
リー状となる。該単粒子の凝集粒子の切断は究極
的には単粒子にまで分散出来るが工業的にはある
程度凝集粒子が残つた段階で乾燥するのが経済的
である。上記スラリー中の凝集粒子の切断状態
は、スラリー状態になつたものの粘度によつて推
定出来る。そして、一般にスラリーの粘度が低い
程凝集粒子は小さく切断されている。一般には水
和珪酸の湿潤ケークに断力又は振動を与えてスラ
リーにした時の粘度が１〜15000センチボイズ好
ましくは10〜5000センチボイズの範囲とするのが
後述する噴霧乾燥を行なう上で好適である。ま
た、スラリーの粘度を下げる為に水を添加するこ
とも出来るが、乾燥工程における所要熱量を増加
させることになるので経済的に不利となる。従つ
て出来るだけ水を加えないで剪断力又は振動のみ
で粘度を低下させるのが好ましい。しかし、スラ
リーの取扱を容易にする為に少量の水を添加する
ことは必要に応じて実施することが出来る。もち
ろん水和珪酸の湿潤ケークを得る場合に含有水分
量が多い状態例えば95（重量）％程度の湿潤ケー
クを得るようにあらかじめ操作すれば上記の通常
得られる湿潤ケークに水を添加したのと同じ結果
となる。湿潤ケークに剪断力又は振動を与えて凝集構造
を破壊する為には、公知の各種ニーダー、コロイ
ドミル、振動ミルあるいはホモジナイザー等の湿
式粉砕機混合機及び強力な撹拌装置等によつて剪
断力を与える方法あるいは超音波、強力振動機等
によつて振動を与える方法によつて容易に実施す
ることが出来る。前記噴霧乾燥は公知の噴霧乾燥機が特に制限さ
れず用いうる。例えば回転円板型乾燥機、加圧ノ
ズル型乾燥機等が好適に用いられる。また得られ
る水和珪酸の粒子径は上記噴霧乾燥の条件を選択
することによつて調節すればよい。例えば、加圧
ノズル型乾燥機を用いた場合はノズルの径、噴霧
圧力、及びスラリー粘度を調節することによつて
粒子径を調節することができる。以上、本発明の水和珪酸の代表的な製造方法を
説明したが、本発明の水和珪酸の製造方法は前記
製造方法に限定されるものではない。本発明の水和珪酸は、吸油速度、吸着力が優れ
ているばかりでなく、従来の水和珪酸に比べて粒
子径が大きいため、取扱い時粉塵の発生がなく、
輸送、或いは使用時に優れた特性を示す。従つ
て、本発明の水和珪酸は種々の用途に好適に使用
される。特に農薬用担体として用いた場合は、農
薬成分の吸着速度が速いばかりでなく農薬成分を
吸着後の粉砕、或いは他の添加剤との混合によつ
ても農薬成分の浸出がほとんどないという驚くべ
き特性を示す。更に、農薬成分の捕捉力も良く、
農薬成分との混合の際、混合機の壁に農薬成分の
付着が全くないということも特筆すべき特性であ
る。以下、本発明を具体的に説明するため実施例を
示すが、本発明はこれらの実施例に限定されるも
のではない。尚、実施例及び比較例に於ける水和珪酸の細孔
容積、149μ〜500μの粒子径を有する粒子の割合、
混合試験、粉砕試験、吸油速度、見掛比重、吸油
量及び細度の測定は以下の方法によつて行なつ
た。 (1) 細孔容積：その細孔容積はカルロエルバ
（CARLOERBA）社製の1520型水銀ポロシオ
メーター（ダイラトメーター（Dilatometer）
タイプSM3、キヤピラリー（Capillary）：３mm
0.07065cm²）を用いて測定した。尚、細孔容積
は細孔半径50〜150Åの細孔の容積として表示
した。 (2) 149μ〜500μの粒子径を有する粒子の割合：
上段に32メツシユのフルイを、下段に100メツ
シユのフルイを配した２段重ねのフルイを用い
て、水和珪酸試料を前記JIS K1474の測定法に
準じてフルイ分けし、全試料重量に対する100
メツシユフルイ上の試料重量の割合を求めて表
示した。 (3) 混合試験：第１図は混合試験に用いる装置を
示す概略図である。第１図に示されるモーター
によつて回転する回転撹拌翼２、及び添加口３
を設けた内容積500mlのポリ容器に水和珪酸試
料５を20ｇ入れ、農薬成分20mlを添加口３より
９〜10分で滴下し、回転撹拌翼の回転数200r.
p.mで滴下開始時より30分間混合する。混合
後、容器内壁及び回転撹拌翼に付着している試
料の重量を測定した。 (4) 吸油速度：第２図〜第４図は吸油速度の測定
方法を示す概略図である。水和珪酸試料５を第
２図に示す如く径70mm、高さ16mmの上面が開口
した容器４に試料の安息角まで入れる。次い
で、第３図に示す如く径110mmの時計皿６に分
銅７を乗せ全重量100ｇとした重しを試料上に
乗せ、圧縮し15秒後に引き上げる。そして、第
４図に示す如く上記圧縮された試料表面にボイ
ル油８を２ml滴下し、ボイル油と試料が接触し
た時からボイル油が試料中に全て吸収されるま
でに要した時間を測定した。尚、測定は気温20℃の室内で行なつた。 (5) 粉砕試験：水和珪酸試料５ｇを蒸発皿に採
る。該試料にボイル油10mlを添加して試料に吸
着させる。上記試料をフイリツプス社製コーヒ
ーミル（家庭用）で粉砕し、粉砕によつて試料
に吸着されたボイル油が浸出して試料が塊状に
なるまでの時間を測定した。 (6) 吸油量：JIS K6220に準じて行なつた。 (7) 見掛比重：JIS K6220に準じて行なつた。実施例１市販の珪酸ソーダ水溶液（モル比3.03、シリカ
濃度26.4％）7.6m³、ボウ硝水溶液（Na₂O濃度
1.48％）33.8m³、及び水3.64m³を内容積60m³、撹
拌機付内部加熱式反応槽に供給した。次いで、撹
拌しながら温度40〜45℃の範囲で硫酸（22ｇ／
100c.c.）1.99m³を約10分で添加した。全酸添加量
に対する上記硫酸の添加割合(A)を第１表に示す。
上記第１段の酸添加終了後、撹拌を継続しながら
水蒸気を吹き込み20分間で第１表に示す反応温度
（Ｔ）まで昇温した。この時のシリカ濃度(C)を第
１表に示す。該溶液を10分間反応温度に保つた
後、撹拌を継続しながら残部の硫酸2.9m³を90分
間で連続的に添加しPH5.5〜6.5として反応を終了
した。上記C₉A、Ｔより求められたＸ値を第１表
に示す。該反応液を、乾燥後の水和珪酸のPHが
5.5〜7.0となるようにPH調整し、フイルタープレ
ス過機を用いて水洗・過した。過によつて
得られた水和珪酸湿潤ケークを強力な撹拌装置に
よつてスラリーの粘度が150C.p.となるまで撹拌
してスラリーとした。該スラリーを回転円板型乾
燥機を用いて400℃で乾燥して水和珪酸を得た。
得られた水和珪酸についての細孔容積、149μ〜
500μの粒子径を有する粒子の割合、吸油速度、
吸油量、及び見掛比重、並びに混合試験、粉砕試
験の結果を第１表に示す。尚、混合試験におい
て、農薬成分は、２−sec−ブチル・フエニル−
Ｎ−メチルカーボネート（以下、B.P.M.C.と略
記する）を用いた。実施例２実施例１において、第１段目の硫酸の添加量を
1.74m³に、残部の硫酸の添加量を3.08m³に、そし
て反応温度を第１表に示すように変えた以外は実
施例１と同様にして水和珪酸を得た。第１表に実
施例１と同様にして測定したシリカ濃度(C)、酸添
加割合(A)、反応温度（Ｔ）、及びＸ値を示す。ま
た、得られた水和珪酸について実施例１と同様な
測定、試験を行なつた結果を第１表に示す。実施例３実施例１と同じ珪酸ソーダ水溶液、ボウ硝水溶
液をそれぞれ2.27m³、13.5m³と水2.02m³を内容積
25m³、撹拌機付の内部加熱式反応槽に供給した。
次いで、撹拌しながら温度40〜45℃の範囲で硫酸
（22ｇ／100c.c.）0.44m³を約10分間で添加した。上
記硫酸の添加割合(A)を第１表に示す。上記第１段
の酸添加終了後、撹拌を継続しながら水蒸気を吹
き込み20分間で第１表に示す反応温度（Ｔ）まで
昇温した。この時のシリカ濃度(C)を第１表に示
す。該溶液を10分間上記反応温度に保つた後、撹
拌を継続しながら、残部の硫酸1.03m³を100分間
で連続添加し、PH5.5〜6.5として反応を終了し
た。上記、Ｃ、Ａ、Ｔより求められたＸ値を第１
表に示す。以下実施例１と同様にして水和珪酸を
得た。得られた水和珪酸について実施例１と同様
な測定、試験を行なつた結果を第１表に示す。実施例４実施例１と同じ珪酸ソーダ水溶液、ボウ硝水溶
液をそれぞれ6.1、27.0と水6.9を内容積50
、撹拌機付の外部加熱式反応槽に供給した。次
いで、撹拌しながら温度40〜45℃の範囲で硫酸
（22ｇ／100c.c.）1.58を約10分間で添加した。上
記硫酸の添加割合(A)を第１表に示す。上記第１段
の酸添加終了後撹拌を継続しながら20分間で第１
表に示す反応温度（Ｔ）まで昇温した。この時の
シリカ濃度(C)を第１表に示す。該溶液を10分間上
記反応温度に保つた後、撹拌を継続しながら残部
の硫酸2.29を100分間で連続添加しPH5.5〜6.5と
して反応を終了した。上記Ｃ、Ａ、Ｔより求めら
れたＸ値を第１表に示す。該反応液を実施例１と
同様にPH調整及び水洗・過して水和珪酸の湿潤
ケークを得た。得られた湿潤ケークをコロイドミ
ル（特殊機化工業製）で粉砕した後、ホモジナイ
ザー（特殊機化工業製）でスラリーの粘度が
100C.P.となるまで粉砕してスラリーとした。該
スラリーを加圧ノズル型乾燥機（商品名：ミニス
プレー、ヤマト科学(株)製）を用いて200℃で乾燥
して水和珪酸を得た。得られた水和珪酸について
実施例１と同様な測定・試験を行なつた結果を第
１表に示す。実施例５実施例４と同様な珪酸ソーダ水溶液、ボウ硝水
溶液、及び反応槽を用い、珪酸ソーダ水溶液8.79
、ボウ硝水溶液27.0及び水4.2を反応槽に
供給した。以下、第１段の硫酸の添加量を2.56
に、残部の硫酸の添加量を3.03に、そして反応
温度を第１表に示すように変えた以外は実施例４
と同様にして水和珪酸を得た。第１表に実施例４
と同様にして測定したシリカ濃度(C)、酸添加割合
(A)、反応温度（Ｔ）、及びＸ値を示す。また得ら
れた水和珪酸について実施例１と同様な測定、試
験を行なつた結果を第１表に示す。比較例１実施例１において、第１段の硫酸の添加量を
1.47に、そして残部の酸の添加量を3.35に変
えた以外は同様にして水和珪酸を得た。第１表に実施例１と同様にして測定したシリカ
濃度(C)、酸添加割合(A)、反応温度（Ｔ）及びＸ値
を示す。また得られた水和珪酸について実施例１
と同様な測定・試験を行なつた結果を第１表に示
す。比較例２実施例１と同じ珪酸ソーダ水溶液４m³、ボウ硝
水溶液（Na₂O濃度1.35％）13.3m³、水0.9m³を実
施例３と同様な反応槽に供給した。次いで撹拌し
ながら温度40〜４℃の範囲で硫酸（22ｇ／100c.c.）
0.9m³を22分で添加した。上記硫酸の添加割合(A)
を第１表に示す。上記第１段の酸添加終了後、撹拌を継続しなが
ら水蒸気を吹き込み30分間で第１表に示す反応温
度（Ｔ）まで昇温した。この時のシリカ濃度(C)を
第１表に示す。該溶液を10分間反応温度に保つた
後、撹拌を継続しながら残部の硫酸1.95m³を50分
間で連続的に添加し、PH5.5〜6.5として反応を終
了した。上記(C)、（Ｔ）、(A)より求められたＸ値を
第１表に示す。以下、実施例１と同様にして水和
珪酸を得た。得られた水和珪酸について、実施例
１と同様な測定・試験を行なつた結果を第１表に
示す。比較例３実施例１と同様な反応、及び過によつて得ら
れた水和珪酸湿潤ケークを静置乾燥した後、ボー
ルミルで粉砕して水和珪酸を得た。得られた水和
珪酸について実施例１と同様な測定・試験を行な
つた結果を第１表に示す。 The present invention provides a novel hydrated silicic acid and a method for producing the same. The hydrated silicic acid of the present invention not only has excellent properties as an agrochemical carrier and a rubber filler, but also is an excellent hydrated silicic acid that can be suitably used in conventionally known fields of use of hydrated silicic acid. Further, the method for producing hydrated silicic acid of the present invention can provide excellent properties with an industrially simple technique. Hydrated silicic acid is produced by various methods and used for various purposes. For example, it can be used as a synthetic rubber filler, a synthetic resin filler, an agricultural chemical carrier, a dental filler, etc. Hitherto, the properties of hydrated silicic acid used in the above applications have been improved by increasing its oil absorption. However, hydrated silicic acid with simply increased oil absorption does not necessarily satisfy the properties required for the above-mentioned uses. That is, hydrated silicic acid produced by conventional methods generally has the drawbacks of slow oil absorption rate and weak ability to support adsorbed substances, that is, weak adsorption power. Therefore, for example, when producing an agricultural chemical using the hydrated silicic acid as a carrier for agricultural chemicals, it takes a long time to adsorb the agricultural chemical components, resulting in a decrease in workability. In addition, when hydrated silicic acid that has adsorbed agricultural chemical components is crushed or mixed with other additives, the adsorbed agricultural chemical components are leached out and the hydrated silicic acid and other additives are used as a binder in a crusher or mixer. Additives and the like may adhere to the surface and cause trouble with the above equipment. Furthermore, since the hydrated silicic acid obtained by conventional methods is in the form of a fine powder with a small agglomerated particle size, which is made up of agglomerated single particles with a particle size of 10 to 50 mμ, dust is likely to be generated during handling, resulting in reduced workability and leading to loss of hydrated silicic acid. In addition, when used as a carrier for the above agricultural chemicals,
The ability to capture the added pesticide ingredients is weak, and the pesticide ingredients adhere to the blades and walls of the mixer that mixes hydrated silicic acid and pesticide ingredients, causing trouble with the mixer. The present inventor has been conducting research on the production of hydrated silicic acid for many years. Furthermore, as a result of pursuing the properties of hydrated silicic acid in various aspects such as reaction conditions and changes over time, we found that hydrated silicic acid with a specific pore size distribution and agglomerated particle size was surprisingly different from the conventional hydrated silicic acid described above. It was discovered that all the drawbacks of silicic acid were eliminated and it exhibited stable properties for a wide variety of uses, leading to the completion and proposal of the present invention. That is, the present invention has a pore radius of 150 Å in the pore size distribution.
The volume occupied by the following pores (hereinafter referred to as pore volume) is 0.5cc/g or more, and the particle size is 149μ~
It is a hydrated silicic acid containing 45% or more of 500μ. In addition, in the present invention, when producing hydrated silicic acid by adding acid to an aqueous alkali silicate solution in multiple stages, the acid addition ratio (A) in the first stage is 20 to 50% of the total acid addition amount, and the acid in the second stage is added. When the silica concentration (C) in the solution is 2 to 6
g/100c.c., and the reaction temperature (T) is within the range of 70 to 100℃, and The reaction is carried out under conditions such that the value of X expressed by , a hydrated silicic acid containing 45% or more of pore size distribution characterized by spray drying, in which the volume occupied by pores with a pore radius of 150 Å or less is 0.5 cc/g or more and the particle size is 149 μ to 500 μ. A manufacturing method is provided. As mentioned above, various types of hydrated silicic acid can be obtained depending on differences in manufacturing methods. Furthermore, the oil absorption amount of hydrated silicic acid can be increased as necessary. However, even hydrated silicic acid having a large oil absorption capacity rarely satisfies the properties required for various uses as described above. That is, even with conventional hydrated silicic acid having a large oil absorption amount, properties such as oil absorption rate and adsorption power are hardly improved. In the present invention, as a result of various statistical experiments, it was confirmed that the above properties are determined by the pore volume of hydrated silicic acid. Note that the pore size distribution as used in the present invention refers to that measured by a mercury porosimeter method unless otherwise specified. In the pore size distribution of hydrated silicic acid, the smaller the pores with a pore radius of 150 Å or less, the greater the effect on properties such as oil absorption rate and adsorption power. It does not have a large effect on properties such as speed and oil absorption. Therefore, in the present invention, the pore volume is the volume occupied by pores with a pore radius of 50 to 150 Å in the pore size distribution, which is particularly important. The hydrated silicic acid of the present invention has a pore volume of 0.5cc/g.
It is necessary to have at least the following. Pore volume is 0.5
If it is smaller than cc/g, properties such as oil absorption rate and adsorption power of hydrated silicic acid will hardly be improved. On the other hand, the larger the pore volume, the better the above properties, but this is accompanied by technical difficulties in producing hydrated silicic acid. Therefore, the pore volume of the hydrated silicic acid in the present invention is 0.5 to 2.0 cc/g, particularly 0.7
It is preferable to select from the range of ~2.0cc/g. Hydrated silicic acid having a pore volume of 0.5 cc/g or more as in the present invention can hardly be found among conventionally known hydrated silicic acids. Incidentally, the pore volume of commercially available hydrated silicic acid is generally about 0.11 to 0.45 cc/g. The total oil absorption amount of the hydrated silicic acid of the present invention is not particularly limited as long as the pore volume is 0.5 cc/g or more. In general, the higher the oil absorption, the better, usually 1.5
A range of 1.8 to 3.5 cc/g is preferred, particularly 1.8 to 3.5 cc/g. In the hydrated silicic acid of the present invention, among the aggregated particles formed by agglomerating single particles, the particle size is 149μ ~
It is important that it contains 45% or more of 500μ. If the particle size is smaller than the above range, dust is likely to be generated when handling the hydrated silicic acid, which not only reduces workability and causes equipment trouble, but also causes problems when used as a carrier for agricultural chemicals, for example. has a weak ability to capture the pesticide ingredients that are mixed with it. Furthermore, if the particle size is larger than the above range, for example, when used as a carrier for agricultural chemicals, it takes time for the agricultural chemical components to penetrate into the inside of the hydrated silicic acid, resulting in a decrease in workability. Also,
It is not preferable to use various fillers because they have poor dispersibility and require re-grinding. In the present invention, it is sufficient that 45% or more of the particles have a particle size within the above range, but it is preferable that the particle size of the particles outside the above range is also close to the particle size within the above range. The apparent specific gravity of the hydrated silicic acid of the present invention is 0.16 to 0.24 g/
A range of cm ³ is preferred. In addition, the particle size is
This is a value measured according to JIS K1474. The hydrated silicic acid of the present invention exhibits its effects only when the two conditions of pore volume and particle size are satisfied. The method for producing the hydrated silicic acid of the present invention is not particularly limited, and any method may be used as long as it satisfies the above two conditions. A typical method for producing the hydrated silicic acid of the present invention will be illustrated below. For example, when producing hydrated silicic acid by adding acid to an alkali silicate aqueous solution in multiple stages and reacting it, then filtering and drying, the ratio of acid addition in the first stage (A) to the total amount of acid added is 20 to 50%. , the silica concentration (C) when adding the second stage acid is 2 to 6 g/100 c.c., and the reaction temperature (T) is within the range of 70 to 100 ° C. The reaction was carried out under conditions such that the value of A method for producing hydrated silicic acid, which is followed by spray drying, is suitable. In the above manufacturing method, sodium silicate, potassium silicate, ammonium silicate, etc. are generally used as the alkali silicate. The molar ratio (M ₂ O/SiO ₂ ; M represents Na, K, NH ₄ , etc.) of the alkali silicate is not particularly limited, but generally
A value of 2.0 to 4.0 is preferably used. Further, as the acid, mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, and acid gases such as carbon dioxide gas and sulfur dioxide gas are generally used. In order to obtain the hydrated silicic acid which is the object of the present invention, it is preferable to carry out the reaction between the alkali alkali silicate aqueous solution and the acid by adding the acid to the alkali silicate aqueous solution in multiple stages. That is, first, a first stage of acid addition is performed to an aqueous alkali silicate solution. The acid addition ratio (A) in the first stage is preferably 20 to 50% of the acid required to neutralize all the alkali silicate. If the acid addition ratio in the first stage is lower than the above range, the single particles of the hydrated silicic acid produced tend to become large, and the pore diameter of the hydrated silicic acid obtained by agglomeration of the single particles tends to become large. Therefore, in the hydrated silicic acid obtained, even if the oil absorption is increased, the pore volume may not be increased in some cases.
In addition, if the acid addition ratio in the first stage is higher than the above range, gelation is likely to occur and the pore volume of the resulting hydrated silicic acid is significantly reduced. It becomes difficult to obtain silicic acid. The temperature in the first stage of acid addition is not particularly limited, but is generally preferably about 10 to 65°C in order to increase the pore volume of the resulting hydrated silicic acid. During the first stage of acid addition, it is generally preferable to carry out appropriate stirring in order to prevent local reactions and prevent gelation. After the first stage of acid addition is completed, it is preferable to maintain the temperature at the reaction temperature while continuing stirring to precipitate hydrated silicic acid seeds. Reaction temperature (T) is 70-100
It is most preferable to select from the range of °C. If the reaction temperature is lower than the above range, gelation is likely to occur and the pore volume of the resulting hydrated silicic acid is significantly reduced, so it may not be possible to obtain hydrated silicic acid with improved properties such as oil absorption rate and adsorption power. Furthermore, if the reaction temperature is higher than the above range, the amount of water evaporated during the reaction will increase, so the silica concentration in the reaction system will fluctuate, and a stable reaction may not be possible. Therefore, in the above reaction, after the first stage acid addition is carried out at a temperature lower than the above reaction temperature, for example, 10 to 65 °C,
A mode in which hydrated silicic acid is precipitated by increasing the temperature and maintaining the reaction temperature is preferable in that hydrated silicic acid having a large pore volume can be obtained. After the first stage of acid addition, when adding the second stage of acid, the silica concentration (C) in the solution is 2 to 6 g/100
It is preferable that the concentration of the alkali silicate used as a raw material is adjusted so that the amount of cc. Also, the silica concentration (C)
can be determined by dividing the weight of silica in the starting alkali silicate aqueous solution by the volume of the total solution. Furthermore, the above silica concentration (C) is determined by the concentration and molar ratio of the raw material alkali silicate aqueous solution, the amount of water added, the first
These conditions should be selected because they vary depending on the amount of water accompanying the acid added in the step, or when heating is performed by blowing steam into the solution to maintain the reaction temperature, the amount of water condensed from the steam, etc. It can be adjusted by When adding the second-stage acid, if the silica concentration (C) in the solution is lower than the above range, the pore volume of the resulting hydrated silicic acid will increase somewhat, but the amount of water in the reaction system will increase and the equipment will need to be It cannot necessarily be said to be industrially advantageous because it leads to an increase in size. Moreover, a large amount of energy is required for heating, overheating, etc., which is often economically disadvantageous. Furthermore, if the silica concentration is higher than the above range, gelation tends to occur and the pore volume of the resulting hydrated silicic acid decreases significantly, making it difficult to obtain hydrated silicic acid with improved properties such as oil absorption rate and adsorption power. It may not be possible. After the first-stage acid addition, the second-stage acid addition is preferably started from the time after the first-stage acid addition when the viscosity of the solution reaches its maximum due to precipitation of hydrated silicic acid seeds. The above acid addition start time varies slightly depending on conditions such as the first stage acid addition temperature, the first stage acid addition ratio, and the reaction temperature, but is 25 to 40 minutes after the first stage acid addition is completed. Generally, this is the case. After the first stage of acid addition is completed, the remaining acid is preferably added continuously or in multiple stages while maintaining the above reaction temperature. In this method, the silica concentration in the solution (C) when adding the acid in the second stage described above, the ratio of acid addition in the first stage to the total amount of acid added (A), and the reaction temperature ( Formula with T) as a function The value of X (hereinafter referred to as X value) expressed by
It is preferable to conduct the reaction so that the ratio is within the range of 1.28 to 1.55. If the X value is lower than the above range, the single particles of hydrated silicic acid will become larger, and the pore size of the hydrated silicic acid obtained by aggregation of the single particles will become larger as a whole, making it difficult to obtain the desired hydrated silicic acid. Sometimes it's not possible. In addition, if the X value is higher than the above range, gelation tends to occur and the pore volume decreases significantly.
In some cases, it may not be possible to obtain hydrated silicic acid with improved properties such as oil absorption rate and adsorption power. In this method, other conditions such as adding an electrolyte such as an alkali metal salt or an alkaline earth metal salt during the reaction, and performing post-treatment such as hydrothermal treatment on the hydrated silicic acid slurry obtained after the reaction is completed. This can be carried out as necessary. The hydrated silicic acid slurry obtained by the above method is filtered using known equipment. For example, it is generally possible to use a filter press such as a filter press type or a rotary type. The hydrated silicic acid obtained by the above filtration is separated as a wet cake. The wet cake is easily turned into a slurry by applying shear force or vibration.
Therefore, once the wet cake is made into a slurry and then spray-dried, it is possible to obtain hydrated silicic acid containing 45% or more of particles having a particle size of 149 μm to 500 μm. By using the above-mentioned reaction conditions, it is possible to obtain hydrated silicic acid having a small single particle diameter, and it is possible to obtain a hydrated silicic acid product having a large pore volume in which the single particles are aggregated. However, it is generally not possible to obtain hydrated silicic acid having the particle size targeted by the present invention simply by drying the wet cake of hydrated silicic acid obtained by the above-mentioned filtration. That is, when hydrated silicic acid is dried in a wet cake state, excessive aggregation of single particles occurs. Therefore, it is necessary to pulverize after drying, which not only complicates the process but also makes it extremely difficult to control the particle size during pulverization. In the above method, by utilizing the thixotropic property of hydrated silicic acid, shearing force or vibration is applied to the wet cake of hydrated silicic acid obtained by filtration to break off the agglomeration of single particles and form a slurry. After that, hydrated silicic acid having the above particle size can be easily obtained by spray drying, which is industrially advantageous. The wet cake of hydrated silicic acid obtained by the above-mentioned filtration generally has a water content of 40 to 90, particularly 50 to 85 (by weight).
It is obtained as a solid with no fluidity of %, but
When a suitable shearing force or vibration is applied to this, the agglomeration of single particles is broken, and the water contained between the agglomerated particles is separated, gradually becoming fluid and forming a slurry. Although the single particles can ultimately be dispersed by cutting the aggregated particles into single particles, from an industrial perspective, it is economical to dry the particles after some aggregated particles remain. The state of cutting of the aggregated particles in the slurry can be estimated from the viscosity of the slurry. In general, the lower the viscosity of the slurry, the smaller the aggregated particles are cut. Generally, when a wet cake of hydrated silicic acid is subjected to shearing force or vibration to form a slurry, the viscosity is in the range of 1 to 15,000 centiboise, preferably 10 to 5,000 centiboise, which is suitable for spray drying as described below. . Additionally, water can be added to reduce the viscosity of the slurry, but this increases the amount of heat required in the drying process, which is economically disadvantageous. Therefore, it is preferable to reduce the viscosity only by shearing force or vibration without adding water as much as possible. However, small amounts of water can be added if desired to facilitate handling of the slurry. Of course, when obtaining a wet cake of hydrated silicic acid, if the operation is performed in advance to obtain a wet cake with a high moisture content, for example, about 95% (by weight), it is the same as adding water to the above-mentioned normally obtained wet cake. result. In order to destroy the agglomerated structure by applying shearing force or vibration to the wet cake, the shearing force is applied using a wet crusher mixer such as various known kneaders, colloid mills, vibrating mills, or homogenizers, powerful stirring devices, etc. This can be easily carried out by a method of applying vibration, or a method of applying vibration using ultrasonic waves, a powerful vibrator, or the like. For the spray drying, any known spray dryer can be used without particular limitation. For example, a rotating disk type dryer, a pressure nozzle type dryer, etc. are preferably used. Further, the particle size of the obtained hydrated silicic acid may be adjusted by selecting the above-mentioned spray drying conditions. For example, when a pressure nozzle dryer is used, the particle size can be adjusted by adjusting the nozzle diameter, spray pressure, and slurry viscosity. Although the typical method for producing hydrated silicic acid of the present invention has been described above, the method for producing hydrated silicic acid of the present invention is not limited to the above-described production method. The hydrated silicic acid of the present invention not only has excellent oil absorption speed and adsorption power, but also has a larger particle size than conventional hydrated silicic acid, so it does not generate dust when handled.
Shows excellent properties during transportation and use. Therefore, the hydrated silicic acid of the present invention can be suitably used for various purposes. In particular, when used as a carrier for agricultural chemicals, it is surprising that not only is the rate of adsorption of agricultural chemical components fast, but there is almost no leaching of agricultural chemical components even when the agricultural chemical components are crushed after adsorption or mixed with other additives. Show characteristics. Furthermore, it has good ability to capture pesticide ingredients,
Another noteworthy characteristic is that when mixing with pesticide ingredients, no pesticide ingredients adhere to the walls of the mixer. Examples are shown below to specifically explain the present invention, but the present invention is not limited to these Examples. In addition, the pore volume of hydrated silicic acid in Examples and Comparative Examples, the proportion of particles having a particle size of 149μ to 500μ,
The mixing test, crushing test, and measurement of oil absorption rate, apparent specific gravity, oil absorption amount, and fineness were performed by the following methods. (1) Pore volume: The pore volume is measured using a mercury porosimeter model 1520 (Dilatometer) manufactured by CARLOERBA.
Type SM3, Capillary: 3mm
0.07065cm ² ). Note that the pore volume was expressed as the volume of pores with a pore radius of 50 to 150 Å. (2) Percentage of particles with a particle size of 149μ to 500μ:
Using a two-tiered sieve with a 32-mesh sieve on the upper tier and a 100-mesh sieve on the lower tier, the hydrated silicic acid sample was divided into sieves according to the measurement method of JIS K1474 mentioned above, and the 100-mesh sieve based on the total sample weight was separated.
The percentage of the sample weight on the mesh was determined and displayed. (3) Mixing test: Figure 1 is a schematic diagram showing the equipment used for the mixing test. A rotary stirring blade 2 and an addition port 3 rotated by a motor shown in FIG.
Put 20g of hydrated silicic acid sample 5 into a plastic container with an internal volume of 500ml, add 20ml of the pesticide component dropwise from addition port 3 over 9 to 10 minutes, and rotate the rotating stirring blade at 200rpm.
pm and mix for 30 minutes from the start of dropping. After mixing, the weight of the sample adhering to the inner wall of the container and the rotating stirring blade was measured. (4) Oil absorption rate: Figures 2 to 4 are schematic diagrams showing a method for measuring oil absorption rate. A hydrated silicic acid sample 5 is placed in a container 4 having an open top with a diameter of 70 mm and a height of 16 mm, as shown in FIG. 2, up to the angle of repose of the sample. Next, as shown in FIG. 3, a weight 7 is placed on a watch glass 6 having a diameter of 110 mm to give a total weight of 100 g, and a weight is placed on the sample, compressed, and lifted after 15 seconds. Then, as shown in Figure 4, 2 ml of boiled oil 8 was dropped onto the surface of the compressed sample, and the time required from the time the boiled oil and the sample came into contact until all the boiled oil was absorbed into the sample was measured. . The measurements were conducted indoors at a temperature of 20°C. (5) Grinding test: Take 5 g of hydrated silicic acid sample in an evaporating dish. Add 10 ml of boiled oil to the sample and let it adsorb onto the sample. The above sample was ground using a Philips coffee mill (for home use), and the time required for the boiling oil adsorbed to the sample to leach out during the grinding and for the sample to form a lump was measured. (6) Oil absorption: Conformed to JIS K6220. (7) Apparent specific gravity: Performed according to JIS K6220. Example 1 7.6 m 3 of a commercially available sodium silicate aqueous solution (molar ratio 3.03, silica concentration 26.4%), 7.6 m ³ of a commercially available sodium silicate aqueous solution (Na ₂ O concentration)
1.48%) and 3.64 m ³ ^of water were supplied to an internally heated reaction tank with an internal volume of 60 m ³ and equipped with a stirrer. Next, add sulfuric acid (22 g/
100 c.c.) 1.99 m ³ was added in about 10 minutes. Table 1 shows the ratio (A) of the sulfuric acid added to the total amount of acid added.
After the first stage of acid addition was completed, water vapor was blown into the reaction mixture while stirring was continued, and the temperature was raised to the reaction temperature (T) shown in Table 1 in 20 minutes. The silica concentration (C) at this time is shown in Table 1. After keeping the solution at the reaction temperature for 10 minutes, the remaining 2.9 m ³ of sulfuric acid was continuously added over 90 minutes while stirring to bring the pH to 5.5 to 6.5 and complete the reaction. Table 1 shows the X values determined from C ₉ A and T above. The reaction solution was dried until the pH of the hydrated silicic acid was
The pH was adjusted to 5.5 to 7.0, and the mixture was washed with water and filtered using a filter press. The hydrated silicic acid wet cake obtained by filtration was stirred with a powerful stirring device until the viscosity of the slurry reached 150 C.p. to form a slurry. The slurry was dried at 400°C using a rotating disc dryer to obtain hydrated silicic acid.
Pore volume for the obtained hydrated silicic acid, 149 μ ~
Percentage of particles with a particle size of 500μ, oil absorption rate,
Table 1 shows the oil absorption amount, apparent specific gravity, and the results of the mixing test and crushing test. In addition, in the mixing test, the pesticide component was 2-sec-butyl phenyl-
N-methyl carbonate (hereinafter abbreviated as BPMC) was used. Example 2 In Example 1, the amount of sulfuric acid added in the first stage was
Hydrated silicic acid was obtained in the same manner as in Example 1, except that the remaining amount of sulfuric acid added was 3.08 ^{m 3} ^and the reaction temperature was changed as shown in Table 1. Table 1 shows the silica concentration (C), acid addition ratio (A), reaction temperature (T), and X value measured in the same manner as in Example 1. Furthermore, the obtained hydrated silicic acid was subjected to the same measurements and tests as in Example 1, and the results are shown in Table 1. Example 3 The same sodium silicate aqueous solution and sulfur nitrate aqueous solution as in Example 1 were used in an internal volume of 2.27 m ³ and 13.5 m ³ and water 2.02 m ³ respectively.
25 m ³ was fed into an internally heated reactor equipped with a stirrer.
Then, 0.44 m ³ of sulfuric acid (22 g/100 c.c.) was added over about 10 minutes at a temperature in the range of 40 to 45° C. while stirring. The addition ratio (A) of the above sulfuric acid is shown in Table 1. After the first stage of acid addition was completed, water vapor was blown into the reaction mixture while stirring was continued, and the temperature was raised to the reaction temperature (T) shown in Table 1 in 20 minutes. The silica concentration (C) at this time is shown in Table 1. After keeping the solution at the above reaction temperature for 10 minutes, the remaining 1.03 m ³ of sulfuric acid was continuously added over 100 minutes while stirring to complete the reaction at a pH of 5.5 to 6.5. The X value obtained from C, A, and T above is the first
Shown in the table. Thereafter, hydrated silicic acid was obtained in the same manner as in Example 1. The obtained hydrated silicic acid was subjected to the same measurements and tests as in Example 1, and the results are shown in Table 1. Example 4 The same sodium silicate aqueous solution and Boron's salt aqueous solution as in Example 1 were prepared at 6.1 and 27.0, respectively, and water was 6.9 at an internal volume of 50.
, to an externally heated reaction tank equipped with a stirrer. Then, 1.58 g of sulfuric acid (22 g/100 c.c.) was added over about 10 minutes at a temperature of 40 to 45° C. while stirring. The addition ratio (A) of the above sulfuric acid is shown in Table 1. After the acid addition in the first stage is completed, the first stage is added for 20 minutes while continuing to stir.
The temperature was raised to the reaction temperature (T) shown in the table. The silica concentration (C) at this time is shown in Table 1. After the solution was kept at the above reaction temperature for 10 minutes, the remaining 2.29 g of sulfuric acid was continuously added over 100 minutes while stirring to bring the pH to 5.5 to 6.5 and complete the reaction. Table 1 shows the X values determined from the above C, A, and T. The reaction solution was adjusted to pH, washed with water, and filtered in the same manner as in Example 1 to obtain a wet cake of hydrated silicic acid. After pulverizing the obtained wet cake with a colloid mill (manufactured by Tokushu Kika Kogyo), the viscosity of the slurry was reduced using a homogenizer (manufactured by Tokushu Kika Kogyo).
It was ground into slurry until it reached 100 C.P. The slurry was dried at 200° C. using a pressure nozzle dryer (trade name: Mini Spray, manufactured by Yamato Scientific Co., Ltd.) to obtain hydrated silicic acid. The obtained hydrated silicic acid was subjected to the same measurements and tests as in Example 1, and the results are shown in Table 1. Example 5 Using the same sodium silicate aqueous solution, sulfur salt aqueous solution, and reaction tank as in Example 4, a sodium silicate aqueous solution of 8.79%
, 27.0 g of aqueous salt solution and 4.2 g of water were supplied to the reaction tank. Below, the amount of sulfuric acid added in the first stage is 2.56
Example 4 except that the remaining amount of sulfuric acid added was changed to 3.03, and the reaction temperature was changed as shown in Table 1.
Hydrated silicic acid was obtained in the same manner. Example 4 in Table 1
Silica concentration (C) and acid addition ratio measured in the same manner as
(A), reaction temperature (T), and X value are shown. Further, the obtained hydrated silicic acid was subjected to the same measurements and tests as in Example 1, and the results are shown in Table 1. Comparative Example 1 In Example 1, the amount of sulfuric acid added in the first stage was changed to
Hydrated silicic acid was obtained in the same manner except that the amount of added acid was changed to 1.47 and the remaining amount of acid added was changed to 3.35. Table 1 shows the silica concentration (C), acid addition ratio (A), reaction temperature (T), and X value measured in the same manner as in Example 1. Further, Example 1 regarding the obtained hydrated silicic acid
Table 1 shows the results of similar measurements and tests. Comparative Example 2 4 m ³ of the same sodium silicate aqueous solution as in Example 1, 13.3 m ³ of a sulfur salt aqueous solution (Na ₂ O concentration 1.35%), and 0.9 m ³ of water were supplied to the same reaction tank as in Example 3. Next, add sulfuric acid (22 g/100 c.c.) at a temperature of 40 to 4°C while stirring.
0.9 m ³ was added in 22 minutes. Addition ratio of the above sulfuric acid (A)
are shown in Table 1. After the first stage of acid addition was completed, water vapor was blown into the reaction mixture while stirring was continued, and the temperature was raised to the reaction temperature (T) shown in Table 1 over 30 minutes. The silica concentration (C) at this time is shown in Table 1. After keeping the solution at the reaction temperature for 10 minutes, the remaining 1.95 m ³ of sulfuric acid was continuously added over 50 minutes while stirring to complete the reaction at a pH of 5.5 to 6.5. Table 1 shows the X values determined from (C), (T), and (A) above. Thereafter, hydrated silicic acid was obtained in the same manner as in Example 1. The obtained hydrated silicic acid was subjected to the same measurements and tests as in Example 1, and the results are shown in Table 1. Comparative Example 3 A hydrated silicic acid wet cake obtained by the same reaction and filtration as in Example 1 was left to dry and then ground in a ball mill to obtain hydrated silicic acid. The obtained hydrated silicic acid was subjected to the same measurements and tests as in Example 1, and the results are shown in Table 1.

【表】該時間で粉砕を中止したものである。
[Table] Grinding was stopped at the specified time.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は混合試験用装置の概略図、第２図、第
３図、及び第４図は吸油速度の測定方法を示す概
略図をそれぞれ示す。また、１は容器、２は回転
撹拌翼、３は添加口、４は容器、５は試料、６は
時計皿、７は分銅、８はボイル油をそれぞれ示
す。 FIG. 1 is a schematic diagram of a mixing test apparatus, and FIGS. 2, 3, and 4 are schematic diagrams showing a method for measuring oil absorption rate. Further, 1 is a container, 2 is a rotating stirring blade, 3 is an addition port, 4 is a container, 5 is a sample, 6 is a watch glass, 7 is a weight, and 8 is boiling oil.

Claims

【特許請求の範囲】１細孔径分布のうち細孔半径150Å以下の細孔
が占める容積が0.5c.c.／ｇ以上で且つ粒子径が
149μ〜500μのものを45％以上含む水和珪酸。２珪酸アルカリ水溶液に酸を多段添加して反応
させた後、濾過及び乾燥して水和珪酸を製造する
に際し、全酸添加量に対する第１段の酸添加割合
(A)が20〜50％、第２段の酸を添加する時の溶液中
のシリカ濃度(C)が２〜６ｇ／100c.c.、及び反応温
度（Ｔ）が70〜100℃の範囲内で、且つで表わされるＸの値が1.28〜1.55となる条件で反
応を行ない上記反応後の液を濾過して水和珪酸の
湿潤ケークを得、該湿潤ケークに剪断力又は振動
を与えてスラリーとした後噴霧乾燥することを特
徴とする細孔径分布のうち細孔半径150Å以下の
細孔が占める容積が0.5c.c.／ｇ以上で且つ粒子径
が149μ〜500μのものを45％以上含む水和珪酸の
製造方法。[Claims] 1. The volume occupied by pores with a pore radius of 150 Å or less in the pore size distribution is 0.5 cc/g or more, and the particle size is
Hydrated silicic acid containing 45% or more of 149μ to 500μ. 2. When producing hydrated silicic acid by adding acid to an aqueous alkali silicate solution in multiple stages and reacting, followed by filtration and drying, the ratio of acid addition in the first stage to the total amount of acid added
(A) is 20 to 50%, the silica concentration in the solution (C) when adding the second stage acid is 2 to 6 g/100 c.c., and the reaction temperature (T) is in the range of 70 to 100 °C. within and The reaction is carried out under conditions such that the value of X expressed by Production of hydrated silicic acid characterized by spray drying, in which the volume occupied by pores with a pore radius of 150 Å or less is 0.5 cc/g or more and the particle size is 45% or more from 149 μ to 500 μ. Method.