JP4063464B2 - Scale-like silica particles, curable composition, cured product comprising the same, and method for producing the same - Google Patents

Description

【０２３８】
〔実施例１１〕（実施例４のシリカスラリーからなる塗料・コーティング剤用の硬化性組成物（厚塗りの場合）から得られる塗膜）
【０２３９】
実施例４の媒体攪拌ビーズミルで処理後のスラリー（固形分濃度１５質量％、平均粒子径１．６μｍ）を、５０ｇビーカーに入れ、スターラーで十分攪拌混合した。
【０２４０】
次に、ＪＩＳ Ｋ ５４００に準拠したガラス板（ソーダライムガラス、７０ｍｍ×１５０ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１２０バーコーター（江藤器械社製）を使って、ガラス板に該スラリーを４回塗布し、室温で乾燥し試験片とした。塗布量は、固形分換算で１００ｇ／ｍ² であった。
【０２４１】
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠して、鉛筆硬度、碁盤目剥離試験、及び耐水性（室温下、水中２４時間）を測定し、結果を表１に示した。
【０２４２】
〔実施例１２〕（実施例４のシリカスラリーからなる塗料・コーティング剤用の硬化性組成物（耐熱性があることを示す例）から得られる塗膜）
【０２４３】
実施例４の媒体攪拌ビーズミルで処理後のスラリー（固形分濃度１５質量％、平均粒子径１．６μｍ）を、５０ｇビーカーに入れ、スターラーで十分攪拌混合した。
【０２４４】
次に、石英ガラス板（１００ｍｍ×１００ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１００バーコーター（江藤器械社製）を使って、石英ガラス板に当該スラリーを塗布し、室温で乾燥した後、さらに６００℃で１時間焼成して試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² であった。
【０２４５】
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠して、鉛筆硬度、碁盤目剥離試験、及び耐水性（室温下、水中２４時間）を測定し、結果を表１に示した。表より、この塗膜は、かなり耐熱性があることが示されている。
【０２４６】
〔実施例１３〕（実施例４のシリカスラリーにエポキシ系水性レジンエマルションを配合した塗料・コーティング剤用の硬化性組成物から得られる塗膜）
【０２４７】
２５０ｍｌプラスチック瓶に、アデカレジンＥＭ０４６０（旭電化工業社製のエポキシ系樹脂の水性エマルション、固形分濃度４０質量％）９．６８ｇと脱塩水３８．７０ｇを秤取し、プラスチック瓶を振って混合した。
【０２４８】
次に実施例４の媒体攪拌ビーズミルで処理後のスラリー（固形分含有量１５質量％）１４５．４０ｇを秤取し、全体が均一になるまで２５０ｍｌプラスチック瓶を、振とう機（イワキ社製、Ｖ−５型）で振とうした後、やや発泡が認められたので、アスピレーターで減圧脱気して硬化性組成物を得た。
【０２４９】
次に、ＪＩＳ Ｋ ５４００に準拠したガラス板（ソーダライムガラス、７０ｍｍ×１５０ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１２０バーコーター（江藤器械社製）を使って、ガラス板に当該スラリーを塗布し、室温で乾燥し試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² であった。塗膜の外観は、平滑でありヒビ割れなどは認められなかった。
【０２５０】
ここで、実施例４の葉状シリカ２次粒子と樹脂エマルションとの固形分での質量比は、８５：１５である。
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠した鉛筆硬度、碁盤目剥離試験、及び耐水性（室温下、水中２４時間）について行い、結果を表１に示した。
【０２５１】
〔実施例１４〕（実施例４のシリカスラリーにアクリルウレタン系市販塗料を配合した塗料・コーティング剤用の硬化性組成物から得られる塗膜）
【０２５２】
２５０ｍｌプラスチック瓶に、水性ウレタンＷ＃１００（旭硝子コートアンドレジン社製のアクリルウレタン系樹脂の水性エマルション、固形分濃度５１質量％）５．９２ｇと脱塩水１５．６０ｇを秤取し、プラスチック瓶を振って混合した。
【０２５３】
これに実施例４の媒体攪拌ビーズミルで処理後のスラリー（固形分含有量１５質量％）に苛性ソーダを添加しｐＨ９．４に調整した後、１１３．３ｇを秤取し、上記プラスチック瓶に添加し、全体が均一になるまで２５０ｍｌプラスチック瓶を、振とう機（イワキ社製、Ｖ−５型）で振とうした後、やや発泡が認められたので、アスピレーターで減圧脱気して硬化性組成物を得た。
【０２５４】
次に、ＪＩＳ Ｋ ５４００に準拠したガラス板（ソーダライムガラス、７０ｍｍ×１５０ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１２０バーコーター（江藤器械社製）を使って、ガラス板に当該スラリーを塗布し、室温で乾燥し試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² であった。塗膜の外観は、平滑でありヒビ割れなどは認められなかった。
【０２５５】
ここで、実施例４の葉状シリカ２次粒子と樹脂エマルションとの固形分での質量比は、８５：１５である。
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠した鉛筆硬度、碁盤目剥離試験、及び耐水性（室温下、水中２４時間）について行い、結果を表１に示した。
【０２５６】
〔実施例１５〕（実施例４のシリカスラリーにフッ素樹脂系市販塗料を配合した塗料・コーティング剤用の硬化性組成物から得られる塗膜）
【０２５７】
実施例４の媒体攪拌ビーズミルで処理後のシリカスラリー（固形分濃度１５質量％）を２５０ｍｌプラスチック瓶に２５０ｇ採取し、界面活性剤イオネットＳ−２０（三洋化成工業社製）１．２５ｇを添加して、プラスチック瓶を振とう機（イワキ社製、Ｖ−５型）で振とうして混合し界面活性剤を含むシリカスラリーとした。この内、１１３．３ｇを分取し、それを以下の試験に用いた。
【０２５８】
上記２５０ｍｌプラスチック瓶に、ボンフロンＷ＃１５００（旭硝子コートアンドレジン社製フッ素樹脂系樹脂の水性エマルション、固形分濃度５１質量％）５．９２ｇと脱塩水３８．７０ｇを秤取した。
【０２５９】
これに、上記の界面活性剤入りのシリカスラリー１１３．３ｇとシリコーンＫＳ−５０８（信越化学工業社製）０．０１５ｇとを添加した後、全体が均一になるまで２５０ｍｌプラスチック瓶を、振とう機（イワキ社製、Ｖ−５型）で振とうして混合して硬化性組成物を得た。
【０２６０】
なお、実施例４のシリカと樹脂エマルションとの固形分での質量比は、８５：１５である。
次に、ＪＩＳ Ｋ ５４００に準拠したガラス板（ソーダライムガラス、７０ｍｍ×１５０ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１００バーコーター（江藤器械社製）を使って、ガラス板に該スラリーを塗布し、室温で乾燥し試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² であった。塗膜の外観は、平滑であり、ヒビ割れなどは、認められなかった。
【０２６１】
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠して、鉛筆硬度、碁盤目剥離試験、及び耐水性（室温下、水中２４時間）を測定し、結果を表１に示した。
【０２６２】
〔実施例１６〕（実施例４のシリカスラリーにシリコン樹脂系市販塗料を配合した塗料・コーティング剤用の硬化性組成物から得られる塗膜）
【０２６３】
実施例４の媒体攪拌ビーズミルで処理後のシリカスラリー（固形分濃度１５質量％）を２５０ｍｌプラスチック瓶に２５０ｇ採取し、界面活性剤イオネットＳ−２０（三洋化成工業社製）１．２５ｇを添加して、プラスチック瓶を振とう機（イワキ社製、Ｖ−５型）で振とうして混合し界面活性剤を含むシリカスラリーとした。この内、１１３．３ｇを分取し、それを以下の試験に用いた。
【０２６４】
上記２５０ｍｌプラスチック瓶に、オーデフレッシュＳｉ−１００（日本ペイント株社製、シリコン樹脂系樹脂の水性エマルション、固形分濃度５４質量％）５．５９ｇと脱塩水４０．０ｇを秤取した。次に、これに、上記の界面活性剤入りのスラリー１１３．３ｇとシリコーンＫＳ−５０８（信越化学工業社製）０．０１３ｇとを添加した後、全体が均一になるまで２５０ｍｌプラスチック瓶を、振とう機（イワキ社製、Ｖ−５型）で振とう混合して硬化性組成物を得た。
なお、実施例４のシリカと樹脂エマルションとの固形分での質量比は、８５：１５である。
【０２６５】
次に、ＪＩＳ Ｋ ５４００に準拠したガラス板（ソーダライムガラス、７０ｍｍ×１５０ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１００バーコーター（江藤器械社製）を使って、ガラス板に該スラリーを塗布し、室温で乾燥し試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² であった。塗膜の外観は、平滑であり、ヒビ割れなどは、認められなかった。
【０２６６】
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠して、鉛筆硬度、碁盤目剥離試験、及び耐水性（室温下、水中２４時間）を測定し、結果を表１に示した。
【０２６７】
〔実施例１７〕（実施例４のシリカスラリーに四弗化エチレン樹脂（以下ＰＴＦＥと称する。）の水性エマルションを配合した塗料・コーティング剤用の硬化性組成物から得られる塗膜）
【０２６８】
２５０ｍｌプラスチック瓶に、ＰＴＦＥの水性エマルション( 旭硝子社製、商品名フルオンＡＤ１、固形分濃度５５質量％）１．８ｇを秤取り、実施例４の媒体攪拌ビーズミルで処理後のシリカスラリー( 固形分濃度１５質量％）６０ｇを上記プラスチック瓶に添加し、全体が均一になるまで２５０ｍｌプラスチック瓶を振とう機( イワキ社製、 Ｖ−５型) で振とうした後、 スラリーをターブラーシェーカーミキサー（シンマルエンタープライゼズ社製、Ｔ２Ｃ型）に入れて、 ３０分間混合・分散させた。
【０２６９】
なお、実施例４のシリカとＰＴＦＥとの固形分での質量比率は、９０：１０とした。
次に、ＪＩＳ Ｋ ５４００に準拠したガラス板（ソーダライムガラス、７０ｍｍ×１５０ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１００バーコーター（江藤器械社製）を使って、ガラス板に該スラリーを塗布し、室温で乾燥した後、さらに３８０℃で２時間熱処理して試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² であった。塗膜の外観は、平滑であり、ヒビ割れなどは、認められなかった。
【０２７０】
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠した鉛筆硬度、碁盤目剥離試験、耐酸性（室温下、５％硫酸中２４時間）、耐アルカリ性（室温下、５％炭酸ナトリウム水溶液中２４時間）、及び耐水性（室温下、水中２４時間）について行い、結果を表２に示した。
【０２７１】
【表２】

【０２７２】
〔実施例１８〕（実施例８のシリカ乾燥微粉末にフッ素樹脂塗料（非水系溶媒使用）を配合した塗料・コーティング剤用の硬化性組成物から得られる塗膜）
【０２７３】
２５０ｍｌプラスチック瓶に、フッ素樹脂塗料( 旭硝子社製、商品名ルミフロンＬＦ−２００、固形分濃度６０質量％）を２５ｇ、硬化剤（旭化成社製、デュラネートＴＰＡ−１００）を２．５ｇ、キシレン２５ｇを秤り取った。
【０２７４】
次に、 実施例８で得られた葉状シリカ２次粒子の微粉末１５ｇを上記プラスチック瓶に添加し、 全体が均一になるまで２５０ｍｌプラスチック瓶を振とう機( イワキ社製、 Ｖ−５型) で振とうした後、スラリーをターブラーシェーカーミキサー（シンマルエンタープライゼズ社製、Ｔ２Ｃ型）に入れて、 ３０分間混合・分散させた。
【０２７５】
次に、ＪＩＳ Ｋ ５４００に準拠した鉄板（７０ｍｍ×１５０ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１００バーコーター（江藤器械社製）を使って、鉄板に当該スラリーを塗布し、室温で乾燥して試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² であった。
【０２７６】
なお、実施例８の葉状シリカ２次粒子とフッ素樹脂塗料との固形分での質量比率は、４６：５４である。
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠した鉛筆硬度、碁盤目剥離試験、耐酸性（室温下、５％硫酸中２４時間）、耐アルカリ性（室温下、５％炭酸ナトリウム水溶液中２４時間）、及び耐水性（室温下、水中２４時間）について行い、結果を表２に示した。
【０２７７】
〔実施例１９〕（実施例４のシリカスラリーにシリカゾルを配合した硬化性組成物から得られる塗膜）
【０２７８】
実施例４の媒体攪拌ビーズミルで処理後のシリカスラリー（固形分濃度１５質量％）４５．３４ｇを５０ｍｌガラス瓶に入れ、次いで、コロイダルシリカ（触媒化成工業社製、商品名カタロイドＳＩ−３０）を４．０ｇ添加し、瓶を振って均一に混合し、硬化性組成物を得た。
【０２７９】
次に、ＪＩＳ Ｋ ５４００に準拠したガラス板（ソーダライムガラス、７０ｍｍ×１５０ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１００バーコーター（江藤器械社製）を使って、ガラス板に該スラリーを塗布し、室温で乾燥して試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² であった。塗膜の外観は、平滑であり、ヒビ割れなどは、認められなかった。
【０２８０】
なお、実施例４の葉状シリカ２次粒子とコロイダルシリカとの固形分での質量比は、８５：１５である。
塗膜の評価としては、ＪＩＳ Ｋ ５４００に準拠した鉛筆硬度、碁盤目剥離試験、及び耐水性（室温下、水中２４時間）について行い、結果を表１に示した。
【０２８１】
〔実施例２０〕（実施例４のシリカスラリーにシリカゲル粉末を配合した硬化性組成物から得られる吸湿性塗膜）
【０２８２】
実施例４の媒体攪拌ビーズミルで処理後のシリカスラリー固形分濃度１５質量％）を４０ｇとイオン交換水６６ｇを２００ｍｌポリ容器に入れて混合した後、Ａ型シリカゲル微粉末ゲル（洞海化学工業社製、平均粒子径４μｍ）５４ｇを添加し、振とう機（イワキ社製、Ｖ−５型）で１０分間振とう混合して硬化性組成物を得た。
【０２８３】
次に、ＪＩＳ Ｋ ５４００に準拠したガラス板（ソーダライムガラス、１００ｍｍ×２００ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ５４００）で、＃１００バーコーター（江藤器械社製）を使って、ガラス板に該スラリーを塗布し、室温で乾燥後、さらに１１０℃で１時間乾燥して試験片とした。塗布量は、固形分換算で１００ｇ／ｍ² であった。塗膜の外観は、平滑であり、ヒビ割れなどは、認められなかった。
【０２８４】
なお、実施例４の葉状シリカ２次粒子とＡ型シリカゲル微粉末との固形分での質量比は、１０：９０である。
この塗膜は、水分の吸着・脱離機能を有しているので、水分の吸着平衡をＪＩＳ ０７０１に準拠した方法として、２５℃で相対湿度を調製したデシケーター内で４８時間静置し吸湿させ、その質量増加率から平衡水分吸着率をもとめた。
【０２８５】
平衡水分吸着率は、試験片を、１８０℃で２時間乾燥後のシリカ塗膜（当該葉状シリカ２次粒子とＡ型シリカゲルの合計質量）の質量を基準にして計算した。結果を表３に示した。
【０２８６】
【表３】

【０２８７】
〔実施例２１〕（実施例４のシリカスラリーにシリカゲル粉末を配合した硬化性組成物から得られる薄層クロマトグラフィ用分離材料）
【０２８８】
実施例４の媒体攪拌ビーズミルで処理後のスラリー（固形分濃度１５質量％）１９．５ｇとイオン交換水１００ｇを２００ｍｌポリ容器に入れて混合した後、液体クロマトグラフィー用の微小真球シリカゲル（洞海化学工業社製、商品名ＭＳゲル、ＥＰ−ＤＦ−７−６０Ａ、平均粒子径７μｍ）５６ｇを添加し、振とう機（イワキ社製、Ｖ−５型）で１０分間振とう混合して硬化性組成物を得た。
【０２８９】
次に、ガラス板（ソーダライムガラス、１００ｍｍ×２００ｍｍ×２ｍｍ厚）を用意して、アプリケーター（谷澤科学社製）を用いて膜厚０．５ｍｍにセットして、上記のスラリーをガラス板の片面に塗布した。塗布されたガラス板は、常温で乾燥後、さらに、１１０℃で１時間乾燥した。
【０２９０】
なお、実施例４の葉状シリカ２次粒子と上記微小真球状シリカゲルとの固形分での質量比率は、５：９５である。
塗膜の外観は、平滑でありヒビ割れなどは認められず丈夫であった。塗布量は、固形分換算で２００ｇ／ｍ² であり、塗膜厚みは、約２５０μｍであった。
【０２９１】
この試験片を用いて、薄層クロマトグラフィとしての性能を、常法に従い測定評価した。展開槽内で親油系（ヘキサン：クロロホルム＝１：１）を用いて分離を行った。
【０２９２】
分離サンプルは、市販の染料溶液（バイエル社製、マクロレックス・グリーン、マクロレックス・バイオレット、保土谷化学工業社製、ＳＯＴブルー、それぞれクロロホルム中濃度０．１％）の混合溶液を、キャピラリーを使用してプレート下端より１５ｍｍの所にスポットし展開距離は、スポットから１５０ｍｍ展開した。
【０２９３】
展開溶媒の距離と分離された各サンプルのスポットの中心の距離を計測し、展開溶媒の展開距離に対する各スポットの距離の比率を算出して、Ｒｆ値とした。評価結果を表４に示した。
【０２９４】
【表４】

【０２９５】
〔実施例２２〕（実施例４のシリカスラリーに微粒子酸化チタンを配合した硬化性組成物から得られる紫外線遮蔽機能を有する塗膜）
【０２９６】
２５０ｍｌプラスチック瓶にフッ素樹脂塗料( 旭硝子社製、 商品名ルミフロンＬＦ−２００、 固形分濃度６０質量％）を２５ｇ、 硬化剤（旭化成社製、デュラネートＴＰＡ−１００）を２．５ｇ、キシレン１２．５ｇを秤取り、 次に、 実施例８で得られた葉状シリカ２次粒子の微粉末を３．９ｇ及び微粒子酸化チタン（石原産業社製、 ＴＴＯ−５１Ａ、 平均粒子径０．０１μｍ、ルチル型) ２．１ｇを、 上記プラスチック瓶に添加し、 全体が均一になるまで２５０ｍｌプラスチック瓶を振とう機（イワキ社製、Ｖ−５型) で振とうした後、スラリーをターブラーシェーカーミキサー（シンマルエンタープライズ社製、Ｔ２Ｃ型）に入れて、 ３０分間振とう混合させた。
【０２９７】
次に、石英ガラス板（１００ｍｍ×１００ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃４０バーコーター（江藤器械社製）を使って、石英ガラス板の片面に当該スラリーを塗布し、室温で乾燥して試験片とした。塗布量は、固形分換算で２０ｇ／ｍ² 、塗膜厚みは３０μｍであった。
【０２９８】
なお、フッ素樹脂塗料と実施例８の葉状シリカ２次粒子微粉末と微粒子酸化チタンとの固形分での質量比率は、７４．５：１６．５：９．０である。
これらの試験片の塗膜評価では、鉛筆硬度は３Ｈであり、碁盤目剥離試験評価点は、８点であった。
【０２９９】
同様にして、石英ガラス板（１００ｍｍ×１００ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃８０バーコーター（江藤器械社製）を使って、石英ガラス板の片面に当該スラリーを塗布し、室温で乾燥して試験片とした。塗布量は、固形分換算で３０ｇ／ｍ² 、塗膜厚みは４５μｍであった。
【０３００】
また同様にして、石英ガラス板（１００ｍｍ×１００ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃１００バーコーター（江藤器械社製）を使って、石英ガラス板の片面に当該スラリーを塗布し、室温で乾燥して試験片とした。塗布量は、固形分換算で３７ｇ／ｍ² 、塗膜厚みは５５μｍであった。
【０３０１】
これらの各試験片について、自記分光光度計（日立製作所社製、Ｕ−４０００型）を用いて、各波長での透過率を測定し紫外線遮蔽性能を求めた。評価結果を表５に示した。
【０３０２】
【表５】

【０３０３】
〔実施例２３〕（実施例４のシリカスラリーに微粒子酸化チタンを配合した硬化性組成物から得られる光酸化触媒機能を有する塗膜）
【０３０４】
２５０ｍｌプラスチック瓶に実施例４の媒体攪拌ビーズミルで処理後のスラリー（固形分濃度15質量％）を秤取り、次に超微粒子酸化チタン（石原産業社製、ＳＴ−０１、平均粒子径０．０１μｍ、アナターゼ型）１２．１ｇを上記プラスチック瓶に添加し、全体が均一になるまで２５０ｍｌプラスチック瓶を振とう機（イワキ社製、 Ｖ−５型) で振とうした後、 スラリーをターブラーシェーカーミキサー（シンマルエンタープライズ社製、Ｔ２Ｃ型）に入れて、 ３０分間混合・分散させた。
【０３０５】
次に、ガラス板（ソーダライムガラス、１００ｍｍ×１００ｍｍ×２ｍｍ厚）を用意し、バーコーター塗り法（ＪＩＳ Ｋ ５４００）で、＃８０バーコーター（江藤器械社製）を使って、石英ガラス板の片面に当該スラリーを塗布し、室温で乾燥して試験片とした後、さらに、５００℃で１時間熱処理して試験片とした。
【０３０６】
塗布量は、固形分換算で３０ｇ／ｍ² であった。塗膜の鉛筆硬度は、Ｂであり、碁盤目剥離試験の評価点は、１０点であった。
【０３０７】
この試験片を塗布側が上になるように、３３．３ｍｇ／Ｌメタノール水溶液５００ｍｌの入ったシャーレ( 内径２００ｍｍ、深さ５０ｍｍ) 中に塗布面が液面より下になるように浸積した。さらに、スターラーで液を攪拌しながら液面から空気が溶解できるようにしつつ、紫外線ランプ（３０Ｗ）を液面の真上から、液面との距離３０ｃｍで、６０時間照射した。
【０３０８】
比較のためのブランクとして、塗布していない同寸法のガラス板を用いて、試験片と同条件で試験した。
照射後のメタノール水溶液を、 ＪＩＳ Ｋ ０１２０のＣＯＤ測定法で液中ＣＯＤ値を測定した。結果を表６に示す。
【０３０９】
【表６】

【０３１０】
〔実施例２４〕（実施例４のシリカ単独での湿式圧縮成型（脱水圧縮成形）による成形体）
【０３１１】
実施例４の媒体攪拌ビーズミルで処理後のスラリー（固形分濃度１５質量％）を、攪拌下、減圧で水分を蒸発濃縮して、固形分濃度３２．８質量％の柔らかい湿ケーキを調整した。
【０３１２】
当該湿ケーキを、１３ｇ秤量し、ペレットプレス機( 内径２０ｍｍ×ストローク５０ｍｍ）のシリンダー内に充填した。なお、シリンダー下部には、濾紙を敷いて脱水できるようにした。
【０３１３】
ピストンを装着して、ハンドプレスで加圧して、ゆっくり１．９６ＭＰａから１９．６ＭＰａまで加圧して、成形体として円柱状の湿ペレット（直径２０ｍｍ、高さ１０ｍｍ）を得た。これを箱型乾燥機を用いて、１２０℃で２時間乾燥し、質量４．１ｇの乾燥ペレット（直径２０ｍｍ、高さ１０ｍｍ）を得た。
【０３１４】
乾燥ペレットの圧縮強度の測定は、圧縮強度試験機（九州丸東社製、９８０Ｎ圧縮強度試験機) に、押し込み棒（先端直径３ｍｍ）を取り付けて、ペレットを圧縮して破壊し、その時のリング変位をマイクロメーターで読み荷重に換算した。ペレットを１０個測定し、ペレット破壊時の圧縮荷重の平均値を求めたところ７１０Ｎであった。
【０３１５】
〔実施例２５〕（実施例８のシリカ単独での乾式圧縮成形による成形体）
実施例８のシリカ乾燥微粉末を３．２ｇ秤り取り、ペレットプレス機( 内径２０ｍｍ×ストローク５０ｍｍ）のシリンダー内に充填した。ピストンを装着して、ハンドプレスで加圧して、ゆっくり１．９６ＭＰａから１９．６ＭＰａまで加圧して、成形体として３．２ｇのペレット（直径２０ｍｍ、高さ１０ｍｍ）を得た。
【０３１６】
ペレットの圧縮強度測定は、実施例２４と同じ方法で行い、ペレット破壊時の圧縮荷重の平均値は、２８４Ｎであった。
【０３１７】
〔実施例２６〕（実施例４のシリカとＡ型シリカゲル混合品の湿式圧縮成形（脱水圧縮成形）による水分吸着機能を有する成形体）
【０３１８】
実施例２４と同じ湿ケーキ（固形分濃度３２．８質量％）２．７７ｇとＡ型シリカゲル水スラリー（固形分濃度１７．８質量％、平均粒子径４μｍ）１０．２３ｇとを混合した後、ペレットプレス機のシリンダー内に充填した。
【０３１９】
ピストンを装着して、ハンドプレスで加圧して、ゆっくり１．９６ＭＰａから１９．６ＭＰａまで加圧して、５．１８ｇの湿ペレットを得た。これれを箱型乾燥機で、１２０℃で２時間乾燥し、成形体として質量３．２ｇの乾燥ペレット（直径２０ｍｍ、、高さ１０ｍｍ）を得た。ペレットの圧縮強度測定は、実施例２４と同じ方法で行い、ペレット破壊時の圧縮荷重の平均値は、１０８Ｎであった。当該ペレット中の葉状シリカ２次粒子とＡ型シリカゲルとの質量比率は、３３．３：６６．７である。
【０３２０】
上記の乾燥ペレットの水分吸着平衡値を、ＪＩＳ Ｚ ０７０１に準拠して測定した。測定結果を表３に示した。
【０３２１】
〔実施例２７〕（実施例８のシリカとＡ型シリカゲル混合品の乾式圧縮成形による水分吸着機能を有する成形体）
【０３２２】
実施例８の葉状シリカ２次粒子の乾燥微粉末１．１ｇとＡ型シリカゲル微粉末（洞海化学工業社製、平均粒子径４μｍ）２．１ｇとを混合した後、ペレットプレス機のシリンダー内に充填した。
【０３２３】
ピストンを装着して、ハンドプレスで加圧して、ゆっくり１．９６ＭＰａから１９．６ＭＰａまで加圧して、湿ペレットを得た。これれを箱型乾燥機で、１２０℃で２時間乾燥し、成形体として質量３．２ｇの乾燥ペレット（直径２０ｍｍ、高さ１０ｍｍ）を得た。ペレットの圧縮強度測定は、実施例２４と同じ方法で行い、ペレット破壊時の圧縮荷重の平均値は、８８．２Ｎであった。当該ペレット中の葉状シリカ２次粒子とＡ型シリカゲルとの質量比率は、３３．３：６６．７である。
【０３２４】
上記の乾燥ペレットの水分吸着平衡値を、ＪＩＳ Ｚ ０７０１に準拠して測定した。測定結果を表３に示した。
【０３２５】
【発明の効果】
本発明の葉状シリカ２次粒子は、自己造膜性を有し、常温においても耐酸性、耐アルカリ性及び耐熱性を併せ有する強固なシリカ被膜を形成しうるものであり、塗料や粒子結着剤（バインダー）として、建物や構築物の外装用あるいは内装用塗料・コーテング剤に有用であり、さらには、熱的機能、光学的機能、吸着機能触媒機能（光触媒など）、対生物機能等を有する塗料・コーティング剤、芳香発生機能を有する塗料・コーティング剤などの種々の用途に有用なものである。
【図面の簡単な説明】
【図１】本発明の葉状シリカ２次粒子を示す走査型電子顕微鏡写真である。
【図２】本発明の葉状シリカ２次粒子を示す透過型電子顕微鏡写真である。
【図３】本発明におけるシリカ３次凝集体粒子を示す走査型電子顕微鏡写真である。
【図４】本発明の葉状シリカ２次粒子からなる塗膜断面の走査型電子顕微鏡写真である。
【図５】シリカ３次凝集体粒子からなる塗膜断面の走査型電子顕微鏡写真である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to scaly silica particles having self-forming properties and capable of forming a strong silica film even at room temperature. More specifically, the present invention relates to a strong silica film having both acid resistance, alkali resistance and heat resistance. The present invention relates to flaky silica particles that can be formed, a curable composition containing the particles, and a method for producing the same.
[0002]
This curable composition is composed of a particle binder (binder), a coating / coating agent for exterior or interior of buildings and structures, a coating / coating agent having a thermal function (heat resistance, heat insulation, fire prevention / flame retardant, etc.), Paints / coating agents with optical functions (ultraviolet shielding, selective light absorption, light emission / fluorescence, etc.), paints with electrical / magnetic functions (electrical insulation, conductivity, antistatic, radio wave absorption, electromagnetic wave shielding, etc.) Coating agent, paint / coating agent with adsorption function (moisture adsorption / desorption, gas adsorption / desorption, thin layer chromatography, etc.) and particle binder (binder) for adsorbent particles, catalytic function (photocatalyst, etc.) Paint / coating agents and particle binders (binders) for catalyst particles, paints / coats with biological functions (antibacterial, anti-fouling, anti-fouling, marine nutrition, cell culture, etc.) Ing agent, fragrance, is useful in various applications such as paints and coatings having a deodorizing function.
[0003]
[Prior art]
Conventionally, various organic paints and coatings have been used, including highly durable paints such as fluororesin paints and acrylic silicon resin paints. However, on the other hand, organic coatings and the like have problems peculiar to these, such as imparting natural pollution resistance, imparting moisture permeability and breathability, escape from organic solvents, and air generated by volatile organic compounds (VOC) in the room. It is necessary to consider many problems such as contamination. In addition, when using photocatalyst particles for antibacterial and dirt prevention, organic paints and binders are used to hold the particles on the substrate, but these generally have poor durability and are also fireproof and flame retardant. There are many problems such as sexual problems. Therefore, the development of inorganic paints and coating agents that are essentially free from these problems has been directed.
[0004]
As inorganic paints / coating agents or particle binders (binders), silicon-based materials are often used from the viewpoint of safety to the human body and the environment. Among the silicon-based materials, there are (1) alkali silicate (water glass) aqueous solution, (2) colloidal silica, (3) organoalkoxysilane, (4) Bentonite, smectite, etc. are known.
[0005]
However, (1) an aqueous solution of alkali silicate has a high alkalinity and has a problem in work safety, and requires a hot air treatment or a heat treatment for curing, and room temperature curing is difficult. (2) Colloidal silica is suitable for particle binders and coating agents and is widely used, but the coating thickness that can be formed by colloidal silica alone is generally less than 10 μm, usually less than 5 μm. If the film thickness is larger than that, the film has many cracks and a strong coating film cannot be obtained. Moreover, generally, heat treatment is required to improve the strength of the coating film. Moreover, since colloidal silica is amorphous silica, it has acid resistance but has a drawback of poor alkali resistance.
[0006]
(3) The organoalkoxysilane has the disadvantages that it requires heat treatment for curing and has poor alkali resistance. Moreover, since these are essentially organic substances, the resulting cured product does not have flame retardancy. (4) Bentonite and smectite are all poor in water resistance, acid resistance and alkali resistance.
[0007]
Silica (= silicon dioxide) is also known among silicon-based materials, but silica other than colloidal silica such as silica gel, hydrous silicic acid (so-called white carbon), quartz, cristobalite, tridymite is a particle binder. Without (binder), there is a problem that the coating film forming function (self-forming property) is extremely poor.
[0008]
In any case, as described above, conventional silica-based film-forming materials have all of room temperature curing properties, thick coating properties, and self-forming properties (coating properties and binder properties), and also have acid resistance and alkali resistance. None of them could form a silica film having all of heat resistance.
[0009]
[Problems to be solved by the invention]
The object of the present invention is to provide a fine scaly silica (= silicon dioxide) which basically solves these drawbacks of conventional silicon-based materials, a curable composition containing it alone or further, It is providing the hardening body which becomes, and its manufacturing method. The cured body is suitable for paints / coating agents, particle binders for molded bodies, and the like.
[0010]
[Means for Solving the Problems]
As a result of intensive studies in view of the importance of the above problems, the inventors of the present invention controlled the fine structure of the particle form in synthesizing the microscale low crystalline silica, and the particle form of the microscale silica was Use is made of fine flaky silica in the form of a layered structure, characterized in that the flaky primary particles are substantially composed of leaf-like silica secondary particles formed by overlapping a plurality of sheets with the plane orientation being parallel to each other. Surprisingly, the inventors have found that the above problems can be basically solved, and completed the present invention.
[0011]
That is, according to the present invention, the following inventions are provided.
(Flaky silica)
(1) Laminate characterized in that flaky primary particles of flaky silica are substantially composed of leaf-like silica secondary particles formed by overlapping a plurality of particles in parallel with each other in parallel with each other, and present independently of each other. Scale-like silica particles having a structured particle morphology.
[0012]
(Curable composition)
(2) A curable composition comprising scaly silica particles having the particle form of the laminated structure according to (1) and a volatile liquid.
Here, the volatile liquid means water and / or a volatile liquid other than water (such as a volatile organic solvent).
[0013]
(3) A curable composition further comprising a low-volatile substance that does not substantially volatilize at a temperature at which the volatile liquid according to (1) volatilizes.
[0014]
(Hardened body)
(4) The flaky silica secondary particles in which the flake primary particles of the flaky silica are aligned in parallel with each other and overlap each other are formed by further laminating the secondary particles in parallel. A cured product characterized by that.
(5) The cured product according to (4), further including the low-volatile substance in the cured product.
[0015]
(Method for producing particles)
(6) A method for producing scaly silica particles for a curable composition,
(I) Any one of silica hydrogel, activated silicic acid or hydrous silicic acid was hydrothermally treated in the presence of an alkali metal salt, and flake primary particles of flaky silica were oriented in parallel with each other and overlapped with each other. Forming flaky silica secondary particles, and scaly silica tertiary aggregate particles comprising tertiary particles having gaps formed by irregularly overlapping the secondary particles in three dimensions; and
(Ii) The foliated silica comprising a step of crushing / dispersing the silica tertiary aggregate particles to obtain foliar silica particles composed substantially of secondary particles substantially free of tertiary particles. A method for producing flaky silica particles having a particle form of a laminated structure substantially consisting of secondary particles.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0017]
1. (Scale-like silica particles having a layered particle form)
First, the scaly silica particles of the present invention and the production method thereof will be described.
[0018]
The scaly silica particles of the present invention are scaly particles having a particle form of a laminated structure consisting essentially of foliar silica secondary particles formed by laminating a plurality of sheets of flake primary particles oriented parallel to each other in parallel. It is silica (hereinafter also referred to as secondary silica particles of the present invention).
[0019]
The flake primary particles have a thickness of 0.001 to 0.1 μm. Such flake primary particles form leaf-like silica secondary particles in which the planes are oriented in parallel with each other and overlap each other, and the thickness of the secondary particles is 0.001 to 3 μm. The ratio (aspect ratio) of the longest length of the leaf-like secondary particles (plate) to the thickness is preferably at least 10, preferably 30 or more, more preferably 50 or more. The ratio of the minimum length of the leaf-like secondary particles (plate) to the thickness is scaly silica having at least 2, preferably 5 or more, more preferably 10 or more. The secondary particles exist independently of each other without fusing.
[0020]
When the thickness of the leaf-like secondary particles is less than 0.001 μm, the mechanical strength of the leaf-like secondary particles becomes insufficient, which is not preferable. On the other hand, when the thickness of the leaf-like secondary particles is larger than 3 μm, the characteristics as a cured product cannot be sufficiently exhibited when used for cured product applications.
[0021]
The upper limit of the ratio of the longest length to the thickness of the leaf-shaped secondary particles and the upper limit of the ratio of the minimum length is not particularly specified, but the former is 300 or less, preferably 200 or less, and the latter is 150 or less, preferably 100 or less is practical.
[0022]
As described above, the thickness and length of the leaf-like secondary particles referred to in the present invention mean an average value for the secondary particles unless otherwise specified.
[0023]
In the present invention, the scale-like shape is not limited as long as the particles have a substantially thin plate-like form, and may be bent or twisted partially or entirely.
[0024]
Such agglomerate particles of silica (tertiary particles) having gaps in which the leaf-like secondary particles are further irregularly overlapped three-dimensionally are so-called silica-X (hereinafter referred to as SiO 2). ₂ -X is also displayed. ) And silica-Y (similarly SiO 2 ₂ -Y is also displayed. ), Etc., the existence of a scientific research object has been known for some time.
[0025]
The leaf-like silica secondary particles of the present invention include such silica aggregate particles (tertiary particles) (for example, Si 2 O 3). ₂ -X and SiO ₂ -Y) is crushed to the leaf-like secondary particles by specific means described later.
[0026]
Silica-X, which is a tertiary aggregate particle of silica, is an intermediate or metastable phase formed in the process of hydrothermal treatment of amorphous silica to form cristobalite or quartz (quartz). It is a weak crystal phase that should be called a quasi-crystalline substance of silica.
[0027]
Although silica-X and silica-Y have different X-ray diffraction patterns, the appearance of particles observed with an electron microscope is very similar, and both are preferable for the purpose of obtaining the secondary silica particles of the present invention. It can be used.
[0028]
Silica X and Silica Y are known per se, but conventional conventional methods for producing Silica-X, etc., use silica gel (silica xerogel), aerosil, precipitated silica, etc. as a starting material, and hydrothermally treat this. However, there was a problem that the reaction time was extremely long. For example, Heydemann, who first discovered silica-X, describes precipitated silica and aerosil (SiCl _Four Is used as a starting material, and it takes an extremely long time of 1.5 to 24 days at 180 ° C. to convert it into silica X in an autoclave. (Heydemann, A., Beitr. Mineral. Petrogr., 10, 242-259 (1964)).
[0029]
On the other hand, for silica-Y, Mitsyuk et al. Have a specific surface area of 600 to 700 m. ² Silica-Y was obtained by hydrothermal treatment for a long time (200 to 220 hours) at a temperature of 145 to 155 ° C. in a solution of NaOH or the like using 1 / g of silica gel as a starting material (Mitsyuk, BA et al. Geochem. Int. 13,101-111 (1976)), Kitahara et al. Has a specific surface area of 600 m. ² / G of silica gel (silica gel (G) manufactured by Wako Pure Chemical Industries, Ltd.) as a starting material and hydrothermally treated at 150 to 160 ° C. for a long time (70 to 170 hours) in NaCl-containing KOH solution. -Y is obtained (Kitahara S, etal. Proc. Inst. Symp. Hydrotherm. React. 1st (1983)).
[0030]
As described above, the method of hydrothermally converting to silica-X or the like using silica gel as a starting material has a problem that an extremely long reaction time (hydrothermal treatment time) is required for industrial application. . Of course, it is possible to shorten the time by raising the temperature of the hydrothermal treatment, but in that case, the stability of the operation range is lost, and a major problem is that quartz (quartz) and cristobalite are easily generated. Provoke.
Thus, the silica aggregate particles (tertiary particles) necessary for obtaining the leaf-like silica secondary particles of the present invention, such as silica-X, at a lower temperature and short enough to be industrially implemented. Therefore, a technique for manufacturing without generating quartz or the like is desired.
[0031]
(1) Formation of silica aggregate particles (tertiary particles)
The leafy silica secondary particles of the present invention are obtained by crushing silica tertiary aggregate particles (tertiary particles) (hereinafter also referred to as silica tertiary aggregate particles in the present invention). The manufacturing method of the silica tertiary aggregate particle used as a precursor particle is demonstrated.
[0032]
From this point of view, the present inventors have proposed two more preferable methods for producing the silica tertiary aggregate particles in the present invention, instead of using the conventional silica gel (silica xerogel) as a starting material.
[0033]
In the first method, silica sol containing a specific amount of a silica source and an alkali source, that is, hydrothermal treatment is performed using an aqueous dispersion of colloidal silica as a starting material, so that silica tertiary aggregate particles such as silica-X can be obtained in a shorter time. And is a method for industrially producing with good stability (Japanese Patent Laid-Open No. 11-29317). According to this method, an aggregate that is a tertiary particle having a gap formed by three-dimensionally irregularly overlapping the leaf-like silica secondary particles of the present invention (that is, the silica tertiary aggregate particles of the present invention). Has the advantage of being obtained as is.
[0034]
This is a method in which a silica sol containing a specific amount of a silica source and an alkali source is hydrothermally treated, and the silica sol has a silica / alkali molar ratio (SiO 2). ₂ / Me ₂ O, where Me represents an alkali metal such as Li, Na or K. same as below. ) Is preferably a silica sol obtained by dealkalizing an alkali silicate aqueous solution of 1.0 to 3.4 mol / mol by an ion exchange resin method or an electrodialysis method. In addition, as an alkali silicate aqueous solution, what diluted water glass with water suitably etc. are preferable, for example.
[0035]
Silica / alkali molar ratio of silica sol (SiO ₂ / Me ₂ O 2) is preferably in the range of 3.5 to 20 mol / mol, more preferably in the range of 4.5 to 18 mol / mol. The silica concentration in the silica sol is preferably 2 to 20% by mass, particularly preferably 3 to 15% by mass.
[0036]
The silica particle diameter in the silica sol means an average particle diameter and is not particularly limited, but is preferably 100 nm or less, and particularly preferably so-called activated silicic acid having a diameter of 20 nm or less. The lower limit of the particle diameter is not particularly limited, but is preferably 1.0 nm or more. When the particle diameter is too large exceeding 100 nm, the stability of the silica sol is lowered, which is not preferable.
[0037]
The method for measuring the silica particle diameter is not particularly limited as long as the particle size can be measured, but the particle size is measured with a laser light scattering particle size measuring device or a transmission electron microscope. be able to.
[0038]
The silica sol as described above is used as a starting material, and this is heated in a heating pressure vessel such as an autoclave and subjected to hydrothermal treatment to produce the silica tertiary aggregate particles in the present invention.
[0039]
The type of the autoclave is not particularly limited, but any autoclave may be used as long as it includes at least a heating unit and a stirring unit, and preferably a temperature measuring unit.
[0040]
Since the silica sol is hydrothermally treated, it is also possible to adjust the silica concentration to a desired range by adding purified water such as distilled water or ion exchange water prior to charging the autoclave.
[0041]
The hydrothermal treatment is performed in a temperature range of 150 to 250 ° C., more preferably 170 to 220 ° C., in order to increase the reaction rate as much as possible and reduce the progress of crystallization.
[0042]
Further, the required hydrothermal treatment time may vary depending on the hydrothermal treatment temperature, the presence or absence of addition of seed crystals, etc., but usually 3 to 50 hours, preferably 3 to 40 hours, more preferably about 5 to 25 hours. It is.
[0043]
In addition, in order to advance hydrothermal treatment efficiently and shorten processing time, the addition is not essential, but it is more preferable to add about 0.001 to 1% by mass of seed crystals. As a seed crystal, silica-X, silica-Y, etc. can be used as they are or after being appropriately pulverized.
[0044]
After the hydrothermal treatment, the hydrothermal treatment product is taken out from the autoclave, filtered and washed with water. The particles after the water washing treatment preferably have a pH of 5 to 9 when a 10% by mass water slurry is formed, and more preferably has a pH of 6 to 8.
[0045]
On the other hand, the second method is a method in which silica hydrogel is used as a starting material and hydrothermally treated in the presence of an alkali metal, and silica-X, silica-Y, etc., which are silica tertiary aggregate particles in the present invention, are used. This is a more preferable method because it can be produced at a low temperature and for a short time without producing crystals such as quartz and with a high yield (Japanese Patent Application No. 10-291336).
[0046]
A silica hydrogel suitable for use as a starting material here is a particulate silica hydrogel. The particle shape of the silica hydrogel may be true spherical (spherical) or amorphous, and the granulating method can be appropriately selected.
[0047]
In the case of a spherical silica hydrogel as an example, the silica hydrosol may be produced by solidifying into a spherical shape in petroleum or other media, as is known for a long time. As described in Japanese Patent Publication No. 48-13834, an alkali silicate aqueous solution and a mineral acid aqueous solution are mixed to form a silica sol in a short time, and at the same time, it is released into a gaseous medium and gelled in the gas. It is manufactured by the method.
[0048]
That is, an alkali silicate aqueous solution and a mineral acid aqueous solution are introduced into a container equipped with a discharge port from a separate inlet and instantaneously and uniformly mixed. ₂ A silica sol having a concentration of 130 g / l or more and a pH of 7 to 9 is generated, and this is immediately discharged from the discharge port into a gaseous medium such as air and gelled in the air while drawing a parabola. To make it happen. An aged tank filled with water is placed at the dropping point, and it is dropped here and aged for several minutes to several tens of minutes.
[0049]
A spherical silica hydrogel preferred for use in the present invention is obtained by adding an acid thereto to lower the pH and washing with water.
[0050]
The silica hydrogel is a transparent and elastic spherical particle having a well-aligned particle size of about 2 to 10 mm. ₂ Contains about 4 times as much water by weight (ie, SiO 2 ₂ 20% by mass and about 80% by mass water).
[0051]
The silica hydrogel particles are actually an aggregate of a large number of silica primary particles having a particle size of about several nanometers, and it is estimated that this water exists on the surfaces and gaps of the primary particles. .
[0052]
SiO in silica hydrogel usable in the present invention ₂ The concentration is preferably 15 to 75% by mass (that is, 85 to 25% by mass of water) from the viewpoint of availability and reactivity, and may be appropriately dried to adjust the moisture content within this range. The water content in the silica hydrogel was measured as follows. That is, after the silica hydrogel sample was dried at 180 C for 2 hours, the remaining sample mass was completely dried SiO 2 ₂ The amount of mass reduction is the amount of water in the sample silica hydrogel.
[0053]
By the way, the silica hydrogel particles are sufficiently dried with a dryer or the like at a temperature of about 150 to 180 ° C., and the hydrogel moisture in the gap and the surface is removed. In the above-described conventional methods for producing silica-X and silica-Y, this dry silica gel is used as a starting material silica for hydrothermal treatment.
[0054]
In the same manner as in the first method using silica sol using such a silica hydrogel as a starting material, it is heated in a heating pressure vessel such as an autoclave and subjected to hydrothermal treatment to obtain the silica tertiary aggregate particles in the present invention. Generate. In that case, the spherical silica hydrogel may be used as it is, but preferably, the spherical silica hydrogel is pulverized or coarsely pulverized so as to have a particle size of about 0.1 to 6 mm, so that stirring in the autoclave can be performed more effectively. Desirable for.
[0055]
In addition, when preparing an autoclave in order to hydrothermally heat the silica hydrogel, it is preferable to adjust the silica hydrogel concentration to a desired range by adding purified water such as distilled water or ion exchange water. The total silica concentration in the treatment liquid in the autoclave is selected in consideration of stirring efficiency, crystal growth rate, yield, etc. ₂ 1 to 30% by mass, preferably 10 to 20% by mass. Here, the total silica concentration in the treatment liquid means the total silica concentration in the system. When not only silica in silica hydrogel but also sodium silicate or the like as an alkali metal salt is used, silicate It is also a value added with silica brought into the system by sodium or the like. The total silica concentration can be made higher than the method using the first silica sol.
[0056]
In hydrothermal treatment, silica hydrogel is allowed to coexist with an alkali metal salt, the pH of the treatment liquid is adjusted to the alkali side, the silica solubility is increased moderately, the crystallization rate based on so-called Ostwald ripening is increased, and the silica hydrogel silica Promote conversion to -X etc.
[0057]
Here, the alkali metal salt means an alkali hydroxide, an alkali silicate, an alkali carbonate or the like. As the alkali metal, Li, Na, or K is preferable. The pH of the system is preferably pH 7 or higher, more preferably pH 8 to 13, and further preferably pH 9 to 12.5.
[0058]
The preferred amount of alkali is the silica / alkali molar ratio (SiO 2 ₂ / Me ₂ O 2) is in the range of 4 to 15 mol / mol, more preferably in the range of 7 to 13 mol / mol. As described above, silica indicates the total amount of silica in the treatment liquid in the system, and is a value obtained by adding silica brought into the system by sodium silicate or the like to silica of silica hydrogel.
[0059]
The hydrothermal treatment is performed in a temperature range of 150 to 220 ° C, preferably 160 to 200 ° C, and most preferably 170 to 195 ° C.
[0060]
If the temperature is too low, it takes a very long time to obtain the target silica tertiary aggregate particles in the present invention. On the other hand, if the temperature is too high, the target silica tertiary aggregate is obtained. The aggregated particles are not preferable because they are difficult to obtain as a single phase such as silica-X or silica-Y. As described above, silica-X or the like is considered to be an intermediate phase or a metastable phase, and has a tendency to successively undergo phase transition to cristobalite or quartz with the progress of hydrothermal treatment. In such a case, the crystallization speed is increased, resulting in a mixture with cristobalite or quartz, or the crystallization reaction is too fast to be controlled, and all changes to cristobalite or quartz. .
[0061]
The required hydrothermal treatment time may vary depending on the hydrothermal treatment temperature, the presence or absence of addition of seed crystals, etc., but is usually 3 to 50 hours, preferably 5 to 40 hours, more preferably about 5 to 25 hours. More preferably, it is about 5 to 12 hours.
[0062]
In addition, in order to advance hydrothermal treatment efficiently and shorten the treatment time, the addition is not essential, but about 0.001 to 1% by mass of seed crystals are added to the charged amount of raw material silica hydrogel. It is more preferable. As the seed crystal, it is preferable to use silica-X, silica-Y, or the like as it is or in an appropriate manner as in the first method.
[0063]
According to the study by the present inventors, when silica-X is used as a seed crystal, aggregate particles composed of silica-X are easily formed, and when silica-Y is used as a seed crystal, aggregate particles composed of silica-Y are used. Is easily formed.
After the hydrothermal treatment is completed, the hydrothermal treatment product is taken out from the autoclave, filtered and washed with water in the same manner as in the first method to adjust the pH.
[0064]
As described above, the particles of the hydrothermally treated product cake obtained by the first method of hydrothermally treating the silica sol and the second method of hydrothermally treating the silica hydrogel are filtered and washed, and the particles in the scanning electron When observed with a microscope (SEM), it can be identified that silica aggregate particles, which are tertiary particles having gaps formed by three-dimensionally irregularly overlapping individual leaf-like secondary particles, are formed. . This is the silica tertiary aggregate particle in the present invention.
[0065]
However, as will be described later, in the scanning electron microscope (SEM), primary particles that are ultrathin flake particles cannot be identified, and a plurality of primary particles that are ultrathin flake particles are oriented in parallel between the planes. Only overlapping leaf-like secondary particles can be identified. On the other hand, when observed using a transmission electron microscope (TEM), primary particles that are ultrathin piece particles through which an electron beam partially transmits can be identified. This leaf-like secondary particle is the leaf-like silica secondary particle of the present invention, and it can be identified that the primary particle is formed of a plurality of layers in parallel with each other between the surfaces. It is practically impossible to separate and isolate the flaky primary particles, which are the structural units, one by one from the leaf-shaped secondary particles in which the primary particles are layered. That is, in the layered overlap of the primary particles, the bonds between the layers are extremely strong and completely fused and integrated, so that the leaf-like secondary particles of the present invention can no longer be broken into primary particles. It is difficult.
[0066]
In addition to the method using silica sol and silica hydrogel as a starting material as described above, the silica tertiary aggregate particles in the present invention can be synthesized by the same method using hydrous silicic acid (so-called white carbon). Can do.
[0067]
(Disintegration of silica tertiary aggregate particles into leaf-like silica secondary particles)
In the present invention, the silica tertiary aggregate particles once produced in this way are crushed by various means to obtain the leaf-like silica secondary particles of the present invention.
[0068]
As the leaf-like silica secondary particles of the present invention, first, the leaf-like secondary particles can be obtained as an aqueous slurry (hereinafter referred to as the secondary particle slurry of the present invention). For example, one of the following methods (2) or (3) can be selected.
[0069]
(2) A method of crushing silica aqueous aggregate particles in the form of water slurry to obtain secondary particle slurry of the present invention.
[0070]
In the above method, the silica aggregate particles obtained in the form of water slurry are then washed with water / solid / liquid separation using a solid / liquid separation / water washing apparatus such as a belt filter, a filter cloth centrifuge, or a decanter. Further, if necessary, SiO 2 composed of the silica tertiary aggregate particles in the present invention having an average particle diameter of 1 to 10 μm substantially not containing an alkali metal salt by repulping with water. ₂ A water slurry having a concentration of 1 to 20% by mass is used.
[0071]
In the pulverization, the slurry is supplied to a wet pulverization apparatus (pulverization apparatus) such as a wet bead mill or a wet ball mill that mechanically stirs at high speed using medium beads to disintegrate the flaky silica tertiary aggregate particles. This is done by crushing. At that time, it is desirable to crush and disperse the leaf-like silica secondary particles without pulverizing and destroying them as much as possible. Among the above methods, medium beads such as alumina or zirconia having a diameter of 0.2 to 1.0 mm are used. The wet bead mill used is particularly preferred. Thus, the crushing step crushes from the tertiary particles to the secondary particles. That is, the obtained slurry is a slurry consisting essentially of the leaf-like silica secondary particles of the present invention in which a plurality of flake primary particles substantially free of tertiary particles are aligned in parallel with each other in plane. It is.
[0072]
SiO in silica slurry supplied to wet pulverizer ₂ When the concentration is less than 1% by mass, the solid concentration is too dilute, which causes a problem in economic efficiency such as the need for concentration in a later step. On the other hand, SiO ₂ When the concentration exceeds 20% by mass, the viscosity of the crushed slurry becomes extremely large, causing a problem in handling.
[0073]
FIG. 1 is a scanning electron microscope (SEM) photograph of the leaf-like silica secondary particles of the present invention thus obtained. With a scanning electron microscope, leaf-like secondary particles can be identified, but ultrathin primary particles cannot be identified. This shows that the said leaf-like silica secondary particle exists mutually independently, without melt | fusion or aggregation.
[0074]
FIG. 2 is a transmission electron microscope (TEM) photograph of the secondary silica particles of the present invention. According to the TEM, it can be confirmed that the ultrathin primary particles and the primary particles are leaf-like secondary particles in which the planes are oriented in parallel and overlap each other.
[0075]
(3) A method of producing a dry powder composed of silica tertiary aggregate particles, and then wet-pulverizing (pulverizing) the slurry to obtain a slurry of the leaf-like silica secondary particles of the present invention.
[0076]
In the production process described above, the silica tertiary aggregate particles obtained in the form of water slurry are then washed with water / solid liquid using a solid / liquid separation / water washing apparatus such as a belt filter, a filter cloth centrifuge, or a decanter. SiO which consists of silica tertiary aggregate particles having an average particle diameter of 1 to 10 μm substantially free of alkali metal salt by separating and, if necessary, repulping with water. ₂ A water slurry having a concentration of 1 to 30% by mass is used.
[0077]
In this case, prior to obtaining the leaf-like secondary particles dispersed by dry crushing, first, a fine powder of the silica tertiary aggregate particles dispersed in the present invention having an average particle diameter of 1 to 10 μm is obtained by drying. is required. However, the silica tertiary aggregate particles have a specific property that the aggregate particles are extremely easily aggregated and fused during the drying operation. According to the study by the present inventors, when a medium fluidized bed dryer is used as a drying device, a finely dispersed dry powder of silica tertiary aggregate particles having an average particle diameter of 1 to 10 μm is obtained for the first time.
[0078]
On the other hand, other drying devices such as airflow dryers, spray dryers, fluidized bed dryers, stirring dryers, cylindrical dryers, box dryers, band dryers, hot air dryers, vacuum dryers, When a vibration dryer or the like is used, the tertiary particles are further aggregated during drying, and a large number of gaps (voids or pockets) formed by irregular overlap of the leaf-like secondary particles are almost obtained. It becomes an unacceptable particle form, and it is difficult to obtain a silica tertiary aggregate particle having an average particle diameter of 1 to 10 μm that is sufficiently dispersed.
[0079]
[FIG. 3] is a scanning electron microscope (SEM) photograph showing the silica tertiary aggregate particles in the present invention thus obtained by drying with a medium fluidized bed dryer. It can be clearly seen that the leaf-like secondary particles overlap irregularly and form silica aggregate particles (tertiary particles) in which there are a large number of gaps (voids or pockets) created by this overlap. The aggregate particles are apparently capable of taking various forms such as cabbage, onion, petal, bud, and conch.
[0080]
Next, water and / or a liquid organic medium is added to the dry fine powder of the silica tertiary aggregate particles having a sufficiently dispersed average particle diameter of 1 to 10 μm, and SiO 2 ₂ A slurry having a concentration of 1 to 30% by mass is used.
[0081]
In the same manner as in (2), this slurry is supplied to a wet pulverizer (pulverizer) such as a wet bead mill or a wet ball mill using a pulverizing medium bead and mechanically stirred at a high speed to obtain silica tertiary aggregate particles. By performing the crushing treatment, the secondary particle slurry of the present invention is obtained.
[0082]
The above is to obtain the secondary particle slurry of the present invention, which can also be obtained as dry particles.
[0083]
As a method for obtaining a dry fine powder of the leaf-like silica secondary particles of the present invention (hereinafter also referred to as the secondary particle dry powder of the present invention), for example, any one of the following (4), (5), (6), etc. Can be selected.
[0084]
(4) A method for obtaining the secondary particle dry powder of the present invention from the water slurry of the above-mentioned (2) leafy silica secondary particles.
[0085]
The monodispersed leaf-like secondary particle dry powder is necessary when using leaf-like silica secondary particles having an average particle diameter of 1 to 10 μm as a non-aqueous solvent-based coating agent.
[0086]
The water slurry of the leaf-like silica secondary particles of the present invention described in (2) has a specific property that the particles are very easily aggregated during the drying operation as described above.
[0087]
Therefore, as drying equipment, air dryer, fluidized bed dryer, medium fluidized bed dryer, stirring type dryer, cylindrical dryer, box dryer, band dryer, hot air dryer, vacuum dryer, vibration dryer, etc. Is used, the leaf-like secondary particles are aggregated, and it is extremely difficult to obtain monodispersed leaf-like silica secondary particles.
[0088]
In this case, using a spray dryer as a drying device, the water slurry composed of the secondary silica particles of the present invention obtained in (2) is dried, and the SiO in the supply slurry is dried. ₂ It has been found that, by adjusting the concentration to 1 to 5% by mass, preferably 1 to 3% by mass and spray-drying, leafy secondary particles having a sufficiently dispersed average particle size of 1 to 10 μm can be obtained for the first time. It was done. SiO in slurry supplied to spray dryer ₂ When the concentration is less than 1% by mass, the amount of water to be evaporated is excessive with respect to silica, which is a serious problem in terms of economy. On the other hand, SiO in the slurry ₂ When the concentration exceeds 5% by mass, aggregation during drying is promoted, so that the leaf-like secondary particles are aggregated and fused, and monodispersed leaf-like silica secondary particles cannot be obtained.
[0089]
(5) A method for obtaining dried leafy silica secondary particles of the present invention from an aqueous slurry of leafy secondary particles of (3) above
[0090]
The dry powder of the monodispersed leaf-like silica secondary particles can be obtained by supplying the water slurry of (3) to a spray dryer and drying the slurry as in (4). However, in this case, the SiO in the supply slurry for the same reason. ₂ It is preferable to adjust the concentration to 1 to 7% by mass, preferably 1 to 5% by mass, and then spray dry.
[0091]
(6) A method of producing a dry powder composed of silica aggregate particles, and then dry-pulverizing (pulverizing) the powder to obtain a fine powder of the secondary silica particles of the present invention.
[0092]
A dry pulverization / classification machine comprising a combination of a dry pulverization function and a dry classification function, for example, a jet By using both a mill and a high-speed rotary classifier or an air classifier, it can be continuously crushed into dispersed leaf-like secondary silica particles having an average particle diameter of 1 to 10 μm. That is, the raw material is continuously supplied to the jet mill, and the pulverized product from the jet mill is classified with a dry classifier, and coarse particles larger than the desired particle size are continuously recycled to the jet mill and pulverized below a predetermined level. It forms a system that continuously takes out the product out of the system.
[0093]
Among the methods described in the above (1) to (6), the method described in the above (1) includes silica hydrogel as a starting material rather than a method using silica sol (active silicic acid or the like) as a starting material. This method is more preferable because of its higher productivity.
[0094]
Moreover, as a method of obtaining the water slurry of the leaf-like silica secondary particles of the present invention described above, the method described in (2) can obtain a water slurry of leaf-like secondary particles more suitable for the curable composition. More preferable.
[0095]
On the other hand, as a method for obtaining the dry fine powder of the leaf-like silica secondary particles described above, the method described in (4) provides a dry fine powder of the leaf-like secondary particles most suitable for the curable composition. More preferable.
[0096]
Hereinafter, basic physical properties of the obtained leaf-like silica secondary particles will be described.
Silica SiO in the silica secondary particles ₂ The purity is 99.0% by mass or more. The pH is 6.0 to 8.0, and the X-ray diffraction spectrum is a card registered in the American Society for Testing and Materials (ASTM) No. 16- (hereinafter simply referred to as the ASTM card). 2θ = 5.6 ° corresponding to silica-X and / or ASTM card number 31-1233, characterized by main peaks of 2θ = 4.9 °, 26.0 °, and 28.3 ° corresponding to 0380, Silica composed of silica-Y characterized by main peaks of 25.8 ° and 28.3 °. The average particle diameter by a Coulter counter (manufactured by Coulter Electronics) is 1 to 10 μm. Oil absorption (JISK5101) is 100-150 ml / 100g.
[0097]
When the pore distribution of the silica secondary particles is measured by the BET method (trade name Belthorpe-28, manufactured by Nippon Bell Co., Ltd.), the pore volume is 0.05 to 0.15 ml / g, and the specific surface area is 30 to 30. 80m ² / G.
[0098]
Of particular note is that the pore distribution curve shows a sharp large peak in the pore diameter range of 2 to 6 nm, particularly around 3.5 to 4.0 nm.
[0099]
This indicates that there are significant pores in the mesopore region (region having a pore diameter of 2 to 50 nm between micro and macro). That is, the leaf-like silica secondary particles of the present invention have a lamellar structure or lamellar particle shape in which the flake primary particles of scaly silica are oriented in parallel with each other and overlap each other. It is inferred that the void formed between the overlapping flakes is measured as a pore having the size of the meso region.
[0100]
In addition, the silica (SiO 2 at room temperature without heat treatment) ₂ ) Infrared absorption spectrum (FT-IR) of 3600-3700 cm ^-1 3400-3500cm ^-1 Silica having silanol groups each having one absorption band. The amount of silanol groups per specific surface area by the BET method is 50 to 70 μmol / m. ² (Several times of silica gel). By having such a silanol group, chemical modification is easily performed. Moreover, by subjecting the coating film formed from the silica secondary particles of the present invention to a heat treatment at about 400 to 600 ° C., the silanol groups can be reacted by condensation or the like to improve the coating film strength.
[0101]
Regarding the heat resistance of the secondary silica particles of the present invention, after heating for 1 hour at 500 to 1000 ° C. in an air atmosphere, the change in the morphology and size of the particles was observed with a scanning electron microscope. I was not able to admit.
[0102]
The saturated solubility at 20 ° C. in acid aqueous solution and aqueous alkali solution is low. That is, dissolved SiO ₂ The concentration is 0.008% by mass for 10% by mass HCl aqueous solution, 0.006% by mass for ion-exchanged water, 0.55% by mass for 5% by mass NaOH aqueous solution, It is 0.79 mass% with respect to a 10 mass% NaOH aqueous solution, shows a low solubility for both acid and alkali, and indicates that it has acid resistance and alkali resistance. In particular, it has a very small solubility in an aqueous alkali solution compared to silica gel and colloidal silica, indicating that it has alkali resistance.
[0103]
The leaf-like silica secondary particles of the present invention have a particle form of a laminated structure as defined in claim 1.
[0104]
Due to such a form, it has a very unique self-forming property and can easily form a strong silica coating even at room temperature. For example, the secondary particle slurry of the present invention (this is a curable composition containing a volatile liquid corresponding to claim 4, that is, water and / or a volatile liquid other than water (such as a volatile organic solvent)). Is coated on a stainless steel or glass substrate and dried at room temperature, it is cured without using any binder or film-forming aid, and a tough coating is easily formed. This coating is very strong and does not easily peel off.
[0105]
This is actually a surprising phenomenon, for example the same SiO 2 as in the present invention. ₂ When an aqueous slurry of silica gel consisting of particles and amorphous porous particles is applied and dried in the same manner on a substrate, a coating film is formed, but this coating film is formed from the secondary particle slurry of the present invention. Compared to coatings that are extremely fragile and that do not resemble even if they are similar, they break apart when touched lightly by hand, and have no commercial value at all. Is in marked contrast.
[0106]
This strong self-forming property and the firmness of the formed film are considered to be due to the following reasons.
[0107]
[FIG. 4] is an SEM photograph of a cross section of a coating film composed of leaf-like silica secondary particles formed by applying and drying the secondary particle slurry of the present invention on a substrate. Looking at this, the leaf-like silica secondary particles are basically constructed by laminating the particles in parallel, but more specifically, each particle form has an appropriate bend, It can be clearly seen that they are oriented in a bent state and closely overlapped. In this way, it is considered that it is difficult to slide in the longitudinal direction (plane direction) because they bend each other and overlap in a wave shape. In addition, since the surface of the particles has a large number of minute irregularities, they are entangled like ridges and have a locking action like an anchor or magic fastener. It seems that a strong film is formed as a whole.
[0108]
In addition, the secondary particles are formed by overlapping flaky primary particles. The flaky primary particles can be separated from each other flake of this structural unit by ordinary means. The leaf-like silica secondary particles of the present invention are constituted by being firmly bonded and integrated with each other to a difficult degree. This is considered to be the reason why the coating film composed of the leaf-like silica secondary particles of the present invention formed with the secondary particles as constituent units (namely, so-called building blocks) is extremely strong.
[0109]
Moreover, the X-ray diffraction pattern of the coating film surface peeled from the base | substrate using the razor was compared with the powder X-ray diffraction pattern of the fine powder used for forming the coating film.
[0110]
Taking silica-X as an example, the ratio of two main peaks corresponding to ASTM card 16-0380, ie, 2θ = 4.9 ° to 2θ = 4.9 °, is the powder In the film, it was 1 to 5, whereas in the coating film, it was a small value of 0.0 to 0.5. This seems to indicate a remarkable orientation of crystal grains in the coating film. Here, the peak height refers to the height from the zero-count baseline.
[0111]
In contrast, particles (silica tertiary aggregate particles) formed by three-dimensionally irregularly overlapping the leaf-like silica secondary particles of the present invention have almost no self-forming property and form a strong coating. Can not do it. [FIG. 5] is an SEM photograph of the cross section of the coating film composed of the silica tertiary aggregate particles. In this case, since the particle morphology is basically not leafy like the secondary particles of the present invention, they are laminated to each other. Therefore, it is clearly observed that it is difficult to form a dense coating film because it cannot be closely overlapped.
[0112]
Similarly, the curable composition comprising the leaf-like silica secondary particles of the present invention and a liquid organic medium that can be dried (this is also the secondary particle slurry of the present invention and corresponds to claim 4). It has self-forming properties, and forms a tough coating easily by drying and curing. In addition, the curable composition prescribed | regulated to Claim 4 or 5 of this invention can form the hardened | cured body of arbitrary shapes by shape | molding this and making it dry and harden | cure not only a coating film. Further, this curing is sufficiently performed only by drying at room temperature, but it is possible to further improve the strength by heat-treating a cured body such as a coating film if desired.
[0113]
(7) A method of using the silica secondary particles of the present invention alone as a curable composition for paints and coating agents.
[0114]
The leaf-like silica secondary particles of the present invention are dispersed in a volatile liquid, that is, water and / or a volatile liquid (such as a volatile organic solvent) other than water, that is, a water slurry and / or an organic solvent slurry. And can be used as a curable composition for forming a cured body such as a coating film on a substrate such as metal, glass, ceramics, and plastics. Here, the volatile liquid is water and / or an organic solvent that can be easily dried at room temperature to 200 ° C., preferably room temperature to 100 ° C., more preferably room temperature to 80 ° C., for example, water, benzene, toluene, Xylene, kerosene, light oil, etc. This is a curable composition corresponding to claim 4, and the SiO in the composition ₂ The concentration is preferably 1 to 80% by mass.
[0115]
(8) A method in which the silica secondary particles of the present invention are blended with other materials and used as a curable composition for paints and coating agents.
[0116]
The leaf-like silica secondary particles of the present invention are used, for example, in a form further containing a low-volatile substance remaining as a liquid or a solid in a cured silica produced by a drying operation, as defined in claim 5. be able to. The term “subjected to the drying operation” means that volatile liquid, that is, water and / or volatile liquid other than water (such as volatile organic solvent) is dried under the above conditions. Specifically, a coating material for forming a cured body such as a coating film on a substrate of metal, glass, ceramics, plastics, etc. in a state of being dispersed in water or other organic solvent together with such residual substances. Used as a curable composition for coating agents.
[0117]
In such curable compositions, SiO ₂ The concentration is preferably 0.1 to 60% by mass.
[0118]
Examples of the low-volatile residual substance in the cured product after drying include a high-boiling liquid substance such as a terpene compound, a saturated hydrocarbon having 12 or more carbon atoms, and glycerin. Another example is an organic polymer material or a precursor material that forms an organic polymer material by a polymerization reaction. In particular, the organic polymer material is a resin emulsion-like material. Examples of other remaining substances are substances having a moisture adsorption and desorption function, in particular, the substance is a substance having a catalytic function, and more specifically, this is a substance having a photooxidation catalytic function, Most preferably this is titanium oxide.
[0119]
Further, the low-volatile substance remaining in the cured body may be a substance having an optical function, and in particular, this substance is a substance having an ultraviolet shielding function, and most preferably, this is titanium oxide, zinc oxide, oxide One or two or more fine particles selected from the group consisting of cerium, iron oxide, and zirconium oxide. Further, the low-volatile substance remaining in the cured body may be amorphous silicon dioxide and / or a metal compound other than silicon dioxide different from the scaly silica in the present invention, as defined in claim 18. Good. In particular, the metal compound is amorphous silicon dioxide different from the flaky silica, for example, amorphous silicon dioxide obtained from silica gel or silicon alkoxide. These may be colloidal particles, and particularly preferably, the colloidal particles are colloidal silica. Naturally, these are included as residual substances in the formed cured body.
[0120]
Here, the colloidal particles in the curable composition are present in the cured body as ultrafine particles having a mean particle diameter of 1 to 200 nm which is substantially the same as the colloidal particle size in the colloidal state. Colloidal particles in the cured product are interpreted as having such a meaning.
[0121]
(9) A method of using the leaf-like silica secondary particles of the present invention alone or in combination with other materials as a curable composition for a molded article by wet molding.
[0122]
In addition, the leaf-like silica secondary particles of the present invention not only form a coating film, but can also form an arbitrary shaped body by curing in a specific mold.
[0123]
That is, the leaf-like silica secondary particles of the present invention are kneaded in the presence of water or other volatile solvent, formed by a molding means such as compression molding or extrusion molding, and then dried and cured to form a molded body. Can do. SiO in the composition in this case ₂ A density | concentration is 1-80 mass%, Preferably it is 20-80 mass%.
[0124]
The silica secondary particles can be kneaded in the presence of water or another organic solvent together with the material substance remaining in the molded body after curing, and molded in the same manner to obtain a molded body. These are so-called wet molding.
[0125]
(10) A method of using the silica alone or in combination with other materials as a curable composition to be dry-molded
[0126]
The leaf-like silica secondary particles of the present invention can be used alone or in combination with other materials in a dry manner, and used as a curable composition for a dry molded body that is formed into a molded body by dry molding such as tableting. . SiO in the composition in this case ₂ Content is 1-100 mass%.
[0127]
2. (Use of the leaf-like silica secondary particles of the present invention in a curable composition or cured product of silica)
[0128]
The leaf-like silica secondary particles of the present invention can be used in various fields such as the performance improvement field of organic paints, the thermal functional field, the optical function, the electrical / magnetic function, the adsorption function, the catalytic function, the biological function, and the aroma / deodorant function. Has application in the field of
[0129]
That is, the silica secondary particles of the present invention are used alone or together with other materials as a curable composition in the field of paints / coating agents, molded articles, and the like, and can be used for producing a cured product.
[0130]
The mixing means for mixing the silica secondary particles of the present invention with a solvent and / or other materials to form a composition is not particularly specified. For example, mechanical stirring and mixing means using slurry stirring blades are applied. The As the stirring blade, a saddle type, a propeller type, a turbine type, an anchor type, a fouler type, and the like can be used as appropriate, but are not limited thereto.
[0131]
As a means for blending silica secondary particles and other materials in the presence of a solvent and particularly uniformly dispersing to form a curable composition, a wet bead mill, a wet ball mill, or the like can be used as appropriate. It is not limited to.
[0132]
The means for applying the curable composition containing the secondary silica particles of the present invention to a substrate to form a coating film is not a specific means, but is applied with a brush, painted with a bar coater, sprayed or electrostatic coated. The means used for painting a general paint can be used. The drying after painting is also not specified, and any applicable means can be used in general paints.
[0133]
As a means for kneading the silica secondary particles of the present invention alone or together with other materials in the presence of water or other organic solvent, a kneader or the like can be used. The molding means is not specified, and generally used dehydration press molding machines, extrusion molding machines, extrusion granulators, spherical granulators, and the like can be used.
[0134]
The dry powder of the silica secondary particles of the present invention alone or together with other dry powder materials is not specified as a means for dry molding after mixing, and is generally used as a mortar type tableting molding. A machine, a roller type pelleter, a press molding machine, etc. can be used.
[0135]
The use of the secondary silica particles of the present invention in various fields will be described below.
1) Performance improvement of conventional organic paints by addition of secondary silica particles of the present invention
[0136]
The silica secondary particles are made of conventional organic paints (acrylic resin-based, epoxy resin-based, urethane resin-based, styrene resin-based, silicon resin-based, fluororesin-based, and copolymer resin-based non-aqueous solvent-based paints, etc. It can be used for improving weather resistance, improving moisture permeability and breathability, improving flame retardancy, etc. by using it together with coating agents and water emulsion paints / coating agents).
[0137]
2) Thermal function
Since the silica secondary particles of the present invention are excellent in heat resistance, they can be used in heat-resistant paints and coating agents by using the silica particles alone or in combination with colloidal silica as defined in claim 22. . In addition, the silica particles can be used as a heat insulating paint / coating agent when used in combination with a glass microballoon having a heat insulating function, zonotlite, foamed silica, heat insulating inorganic fibers (silica alumina fibers, etc.), and the like.
[0138]
Moreover, the said silica secondary particle can be utilized also for the coating material and coating agent which improved the flame retardance by using the conventional organic coating material and a flame retardant together.
[0139]
3) Optical functions
The leaf-like silica secondary particles of the present invention can be used together with an organic ultraviolet shielding agent or an inorganic ultraviolet shielding agent (titanium oxide, zinc oxide, cerium oxide, iron oxide, zirconium oxide, etc.) to provide a paint having an ultraviolet shielding function.・ It can be used as a coating agent. In addition, the silica particles can be used in paints / coating agents having a light selective transmission function when used in combination with a light selective transmission functional material such as infrared absorption (tin oxide, composite metal hydroxide condensed silicate, etc.). . When used together with a substance having a fluorescent function such as a fluorescent pigment or a fluorescent substance, it can be used for forming a paint / coating agent having a fluorescent function.
[0140]
4) Electrical and magnetic functions
The silica secondary particles of the present invention can be used for paints and coating agents having electrical insulation. The silica particles can be used for conductive or antistatic paints / coating agents when used in combination with a conductive material or an antistatic material. In addition, the silica particles can be used together with filler materials (metal powder, carbon powder, ferrite powder, etc.) that give radio wave absorption function or electromagnetic wave shielding function to paints / coating agents having radio wave absorption function or electromagnetic wave shielding function. Available. Further, the silica particles can be used for paints / coating agents having a specific dielectric constant when used in combination with a material having a specific dielectric constant.
[0141]
5) Adsorption function
The silica secondary particles of the present invention are cured with moisture adsorption or moisture absorption / moisture release functions when used in combination with a moisture adsorbent such as silica gel or synthetic zeolite (Na-A type zeolite, Ca-A type zeolite, etc.). Can be used for body, paint and coating agent. Moreover, in the use only for moisture adsorption, the cured body and the coating material / coating agent can be used as, for example, an internal desiccant for multi-layer glass. In addition, the silica secondary particles are used in combination with a material having a gas adsorption function (activated carbon, alkaline earth metal-substituted A-type synthetic zeolite, alkaline earth metal-substituted X-type synthetic zeolite, silica gel, etc.). It can be used as a cured product with an adsorption function, paint and coating agent. Moreover, the said silica secondary particle can be utilized as a particle | grain binder (binder) for the shaping | molding particle | grains of various adsorbents.
[0142]
In addition, the silica secondary particles of the present invention are used as a particle binder (binder) for silica gel fine particles for liquid chromatography (the particle shape may be either spherical or indeterminate), and are coated on a substrate. Can be used as a separation material for thin layer chromatography. In this case, in order to improve the developing speed of the developing solvent, a water-soluble polymer such as sodium polyacrylate, polyvinyl alcohol, polyvinyl pyrrolidone or the like is used as a particle binder together with the silica secondary particles of the present invention. You can also.
[0143]
6) Catalytic function
The silica secondary particles of the present invention can be used in paints / coating agents having a catalytic function when used in combination with a catalyst material (for example, a photo-oxidation catalyst material such as titanium oxide). The silica particles can be used as a particle binder (binder) for various catalyst particles. In addition, a coating film intensity | strength and water resistance can be improved by heating the coating film formed as needed to about 200-600 degreeC.
[0144]
The above-described photo-oxidation catalyst particle binder can be used for photo-oxidation catalyst and photo-catalytic surface-superhydrophilic applications. In addition, a self-film-forming property of the silica secondary particles of the present invention is used to form a coating film made of this and titanium oxide on the surface of a light-transmitting filler (for example, glass Raschig ring). It can be used as a catalyst for water treatment to remove BOD and COD from waste water.
[0145]
7) Biological function
The silica secondary particles of the present invention can be used for paints / coating agents having an antibacterial function when used in combination with materials having an antibacterial function (such as metallic silver, silver compounds, silver-substituted synthetic zeolite, and zinc-substituted synthetic zeolite). Further, the silica particles can be used for paints / coating agents having an antifungal function when used in combination with an antifungal agent. Furthermore, the silica particles can be used for other biological functions (such as ship bottom antifouling paints, fishery nutrient sustained release substrates, cell culture substrates, etc.).
[0146]
8) Aroma and deodorant function
The silica secondary particles of the present invention can be used in paints / coating agents having an aroma / deodorizing function by using in combination with a fragrance or a material having a deodorizing function.
[0147]
9) Protection function for plastic substrate
The silica secondary particles of the present invention are formed by forming a coating film on a plastic substrate (film, plate, etc.), thereby improving the scratch resistance of the substrate and chemically degrading the substrate due to a photocatalytic reaction. It can be used for protection.
[0148]
3. (Use of the leaf-shaped secondary particles of the laminated structure of the present invention in other fields)
The leaf-like silica secondary particles of the present invention can be used for applications other than the above-described curable composition and cured product. As other applications, for example, it can be used in various cosmetic fields. The same cosmetic application as proposed in the patents previously filed by the present inventors (Japanese Patent Laid-Open Nos. 11-5716, 11-11927, and 10-164401), that is, cleansing makeup It can be used for cosmetics, hair cosmetics, basic cosmetics, makeup cosmetics, tan / sunscreen cosmetics, nail cosmetics, eyeliner cosmetics, lip cosmetics, oral cosmetics, bath cosmetics and the like.
[0149]
Moreover, as a use other than the curable composition of the silica secondary particle of the present invention and the cured product, the silica has a laminated structure or a lamellar structure. It is a material in which pores in the meso region of 4.0 nm are remarkably present, and belongs to so-called mesoporous silica, so that it can be used as a host for an intercalation reaction.
[0150]
Further, the secondary silica particles of the present invention can be used as an adsorbing / separating agent utilizing mesopores, a catalyst, a catalyst carrier, and the like.
[0151]
In addition, the silica secondary particles of the present invention can be used for various functional materials utilizing changes in structure and physical properties by surface modification.
[0152]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
[Example 1] (Production of silica tertiary aggregate particles using hydrogel as a starting material)
The starting silica hydrogel was prepared as follows using sodium silicate as an alkali source. SiO ₂ / Na ₂ O = 3.0 (molar ratio), SiO ₂ A sodium silicate aqueous solution having a concentration of 21.0% by mass of 2000 ml / min and a sulfuric acid aqueous solution having a sulfuric acid concentration of 20.0% by mass are introduced into a container equipped with a discharge port from a separate inlet and instantaneously uniform. Mix and adjust the flow ratio of the two liquids so that the pH of the liquid discharged from the discharge port into the air is 7.5 to 8.0, and the silica sol solution that is uniformly mixed is continuously aired from the discharge port. Released inside. The discharged liquid became spherical droplets in the air and gelled in the air while drawing a parabola and staying for about 1 second. A ripening tank filled with water was placed at the dropping point, and it was dropped and aged here.
[0153]
After aging, the pH was adjusted to 6 and washed thoroughly with water to obtain a silica hydrogel. The obtained silica hydrogel particles had a spherical particle shape and an average particle diameter of 6 mm. SiO in the silica hydrogel particles ₂ The mass ratio of water to mass was 4.55 times, and the residual sodium in the silica hydrogel particles was 110 ppm.
[0154]
The silica hydrogel particles were coarsely pulverized to an average particle size of 2.5 mm using a double roll crusher and used in the subsequent hydrothermal treatment step.
[0155]
In the autoclave with a capacity of 50000 ml (electrically heated, with anchor type stirring blades), the total SiO in the system ₂ / Na ₂ The silica hydrogel (SiO 2) having a particle size of 2.5 mm so that the O molar ratio is 12.0. ₂ 18 mass%) 23.7 kg and sodium silicate aqueous solution (SiO ₂ 28.75% by mass, Na ₂ O9.3 mass%, SiO ₂ / Na ₂ O = 3.17 (molar ratio))) 5.5 kg was added, and 10.7 kg of ion exchange water was added thereto, and hydrothermal treatment was performed at 185 ° C. for 8 hours while stirring at 50 rpm. The total silica concentration in the system is SiO ₂ As 15% by mass.
[0156]
The slurry after the hydrothermal treatment was washed with filtered water using a filter cloth type vertical centrifuge (manufactured by Toko Machine Co., Ltd., TU-18 type), and the solid water content was 69.7% by mass (solid content concentration: 30.3). (Mass%) silica wet cake was obtained.
[0157]
Water is added to the wet cake and repulped, and SiO ₂ After making the slurry of 7.0 mass% silica, using a medium fluidized bed dryer (Okawara Seisakusho, SFD-MINI type), it is dried at a hot air temperature of 300 ° C. to obtain 5.6 kg dry fine powder. It was.
[0158]
When the product phase of the fine powder was identified by the powder X-ray diffraction spectrum, the main peaks of 2θ = 4.9 ° and 26.0 ° corresponding to ASTM card number 16-0380 were found as the X-ray diffraction spectrum. In addition to the main silica-X peak, the peaks corresponding to ASTM card numbers 31-1235 and 37-0386 were observed. The ratio of the peak height at 2θ of 26.0 ° to the peak height at 2θ of 4.9 ° was 2.5.
[0159]
Further, the oil absorption (JIS K 5101) of this fine powder was measured and found to be 110 ml / 100 g.
[0160]
When the form of the generated particles was observed with a transmission electron microscope (TEM), the flake-like thin primary particles were oriented in parallel with each other in parallel, and a plurality of sheets were overlapped to form leaf-like silica secondary particles. Was observed.
[0161]
On the other hand, when the form of the generated particles was observed with a scanning electron microscope (SEM), the primary particles could not be identified, and were observed as if the leaf-like silica secondary particles were primary particles. The shape of the leaf-like particles was scaly, and it was observed that silica tertiary aggregate particles having a large number of gaps (voids or pockets) overlapped irregularly. This is the silica tertiary aggregate particle in the present invention.
[0162]
The average longest length of the plate with respect to the average thickness of 0.06 μm of the portion of the leaf-like particles (corresponding to secondary particles in TEM) observed with a scanning electron microscope (SEM) is 5. The aspect ratio was 90 at 4 μm, the average minimum length of the plate was 1.6 μm, and the aspect ratio was 27.
[0163]
When the average particle diameter of this fine powder (silica tertiary aggregate particles) was measured using a Coulter counter (manufactured by Coulter Electronics, MAII type, aperture tube diameter 50 μm (the same in Examples 1 to 9 below)), It was 6.1 μm.
[0164]
Furthermore, when the amount of crystalline free silicic acid in the fine powder was measured by X-ray diffraction analysis, it was found to be below the detection limit (2% or less).
[0165]
[Example 2] (Production of silica tertiary aggregate particles using hydrogel as a starting material)
The starting silica hydrogel was prepared as follows using NaOH as an alkali source. SiO ₂ / Na ₂ O = 3.0 (molar ratio), SiO ₂ A sodium silicate aqueous solution having a concentration of 21.0% by mass of 2000 ml / min and a sulfuric acid aqueous solution having a sulfuric acid concentration of 20.0% by mass are introduced into a container equipped with a discharge port from a separate inlet and instantaneously uniform. Mix and adjust the flow ratio of the two liquids so that the pH of the liquid discharged from the discharge port into the air is 7.5 to 8.0, and the silica sol solution that is uniformly mixed is continuously aired from the discharge port. Released inside. The discharged liquid became spherical droplets in the air and gelled in the air while drawing a parabola and staying for about 1 second. A ripening tank filled with water was placed at the dropping point, and it was dropped and aged here.
[0166]
After aging, the pH was adjusted to 6 and washed thoroughly with water to obtain a silica hydrogel. The obtained silica hydrogel particles had a spherical particle shape and an average particle diameter of 6 mm. SiO in the silica hydrogen particles ₂ The mass ratio of water to mass was 4.38 times, and the residual sodium in the silica hydrogel particles was 112 ppm.
[0167]
The silica hydrogel particles were coarsely pulverized to an average particle diameter of 2.5 mm using a double roll crusher, and used for the processing step of the next step.
[0168]
In a 5000 ml autoclave (electrically heated, with anchor type stirring blades), total SiO in the system ₂ / Na ₂ Silica hydrogel (SiO 2) having a particle size of 2.5 mm so that the O molar ratio is 11.0. ₂ (18.6% by mass) 2688 g and sodium hydroxide aqueous solution (NaOH 48.5% by mass) 126 g, and 1186 g of ion-exchanged water were added thereto, 0.5 g of seed crystals were added, and the mixture was stirred at 20 rpm at 180 ° C Hydrothermal treatment was performed for 12 hours. The total silica concentration in the system is SiO ₂ 12.5% by mass.
[0169]
The slurry after the hydrothermal treatment was washed with filtered water using a filter cloth vertical centrifuge (manufactured by Toko Machine Co., Ltd., TU-18 type), and the solid water content was 66.7% by mass (solid content concentration: 33.3). (Mass%) silica wet cake was obtained.
[0170]
Next, water is added to the wet cake and repulped, and SiO ₂ After preparing a slurry of silica having a concentration of 7.0% by mass, it was dried at a hot air temperature of 300 ° C. using a medium fluidized bed dryer (manufactured by Okawara Seisakusho, SFD-MINI type) to obtain 408 g of dry fine powder.
[0171]
The resulting fine powder was identified by a powder X-ray diffraction spectrum. As a result, 2θ = 5.6 °, 25.8 ° and 28.3 ° corresponding to ASTM card number 31-1233 were obtained as the X-ray diffraction spectrum. Peaks corresponding to ASTM card numbers 35-63 and 25-1332 were observed in addition to the silica-Y main peak characterized by
[0172]
Further, the oil absorption (JIS K 5101) of this fine powder was measured and found to be 100 ml / 100 g.
[0173]
When the form of the generated particles was observed with a transmission electron microscope (TEM), the flake-like thin primary particles were oriented in parallel with each other in parallel, and a plurality of sheets were overlapped to form leaf-like silica secondary particles. Was observed.
[0174]
On the other hand, when the form of the generated particles was observed with a scanning electron microscope (SEM), the primary particles could not be identified, and were observed as if the leaf-like silica secondary particles were primary particles. The shape of the leaf-like particles was scaly, and it was observed that the silica tertiary agglomerate particles in the present invention in which the particles overlap irregularly and have a large number of gaps (voids or pockets) are formed.
[0175]
While the average thickness of the leaf-like silica particles (corresponding to secondary particles in the TEM) observed with this scanning electron microscope (SEM) is 0.07 μm, the average longest length of the plate with respect to the thickness is 6.0 μm. The aspect ratio was 86, the average minimum length of the plate was 1.8 μm, and the aspect ratio was 26.
[0176]
Moreover, it was 6.5 micrometers when the average particle diameter of this fine powder was measured using the Coulter counter (Coulter Electronics Co., Ltd. make, MAII type | mold).
[0177]
Furthermore, when the amount of crystalline free silicic acid in the fine powder was measured by X-ray diffraction analysis, it was found to be below the detection limit (2% or less).
[0178]
[Example 3] (Production of silica tertiary aggregate particles using activated silicic acid as a starting material)
Na ₂ O2.42 mass%, SiO ₂ 7.36% by mass (SiO ₂ / Na ₂ O = 3.13 (molar ratio)) sodium silicate aqueous solution was adjusted to 5400 g, and Na dialysis tank (manufactured by Asahi Glass Co., Ltd., DS-0 type tank) was used. ₂ O1.35 mass%, SiO ₂ 9.16% by mass (SiO ₂ / Na ₂ Sodium removal was carried out until O = 7.0 (molar ratio)) to obtain silica sol (active silicic acid).
[0179]
The average particle size of the obtained colloidal silica of active silicic acid was 3 nm or less as measured with a laser scattering particle size measuring device manufactured by Otsuka Electronics.
[0180]
Next, 2183 g of the above active silicic acid and 1817 g of ion-exchanged water were charged into a 5000 ml autoclave (electrically heated, with anchor type stirring blades) as a hydrothermal treatment apparatus, 0.5 g of seed crystals were added, and the mixture was stirred at 200 rpm. However, hydrothermal treatment was performed at 200 ° C. for 8.5 hours.
[0181]
The slurry after the hydrothermal treatment was washed with filtered water using a filter cloth type vertical centrifuge (manufactured by Toko Machine Co., Ltd., TU-18 type), and the solid water content was 68.7% by mass (solid content concentration 31.3). (Mass%) silica wet cake was obtained.
[0182]
Next, water is added to the wet cake and repulped, and SiO ₂ After preparing a slurry of silica having a concentration of 7.0% by mass, it was dried at a hot air temperature of 300 ° C. using a medium fluidized bed dryer (manufactured by Okawara Seisakusho, SFD-MINI type) to obtain 151 g of dry fine powder.
[0183]
When the produced fine powder was identified by the powder X-ray diffraction spectrum, the X-ray diffraction spectrum was characterized by main peaks of 2θ = 4.9 ° and 26.0 ° corresponding to ASTM card number 16-0380. It was found to be a single phase of the main peak of silica-X.
[0184]
The oil absorption (JIS K 5101) of this fine powder was measured and found to be 105 ml / 100 g.
[0185]
When the form of the generated particles was observed with a transmission electron microscope (TEM), the flake-like thin primary particles were oriented in parallel with each other in parallel, and a plurality of sheets were overlapped to form leaf-like silica secondary particles. Was observed.
[0186]
On the other hand, when the form of the generated particles is observed with a scanning electron microscope (SEM), the primary particles cannot be identified, and are observed as if the foliar silica secondary particles are primary particles. The shape of the leaf-like particles was scaly, and it was observed that the silica tertiary agglomerate particles in the present invention in which the particles overlap irregularly and have a large number of gaps (voids or pockets) are formed.
[0187]
While the average thickness of the leaf-like silica particles (corresponding to secondary particles in TEM) observed with this scanning electron microscope (SEM) is 0.05 μm, the average longest length of the plate with respect to the thickness is 3 μm and its aspect The ratio was 60, the average minimum length of the plates was 1.2 μm, and the aspect ratio was 24.
[0188]
Further, the average particle size of the fine powder was measured using a Coulter Counter (manufactured by Coulter Electronics Co., Ltd., MAII type) and found to be 5.1 μm.
[0189]
Furthermore, when the amount of crystalline free silicic acid in the fine powder was measured by X-ray diffraction analysis, it was found to be below the detection limit (2% or less).
[0190]
[Example 4] (Production of slurry-like secondary silica particles of the present invention from the wet cake of Example 1)
[0191]
1020 g of water was added to 1000 g (solid content concentration: 30.3% by mass) of the wet cake after filtration and washing with the centrifuge shown in Example 1, and repulped to prepare a silica slurry having a solid content of 15% by mass. In this slurry state, the average particle diameter measured by a Coulter counter was 7.2 μm, and the viscosity measured by a B-type viscometer was 0.010 Pa · s.
[0192]
Next, this slurry was mixed with a medium stirring bead mill (Shinmaru Enterprises Co., Ltd., Dynomill KDL-PILOT A type (Bessel capacity 1.4 L, diameter 0.5 mm zirconia beads 80% filled)) at a shaft rotation speed of 3400 rpm and a flow rate of 30 L / h. Then, the silica tertiary aggregate particles were crushed and dispersed.
[0193]
The average particle diameter of the fine particles in the slurry after pulverization / dispersion by a Coulter counter was 1.6 μm. Moreover, it was 0.13 Pa * s when the viscosity of this slurry was measured with the B-type viscosity meter.
[0194]
Next, in order to investigate the physical properties of the dried leafy silica secondary particles close to the state of the fine particles in the slurry, a dry powder was obtained by the following method.
[0195]
Since the slurry has a unique property that it is very easy to agglomerate by drying, it is necessary to form a water slurry with a very thin concentration and dry it while preventing aggregation in order to obtain a monodispersed dry powder. .
[0196]
Water was added to the slurry (solid content concentration of 15% by mass) to adjust the slurry concentration to a solid content concentration of 0.3% by mass.
[0197]
The slurry is spray-dried at a slurry supply rate of 1.7 ml / min, a spray pressure of 0.3 MPa (G), and a hot air temperature of 130 ° C. using a small spray dryer (manufactured by Yamato Kagaku Co., GA32 type). Got.
The average particle diameter of the obtained dry fine powder by a Coulter counter was 1.9 μm.
[0198]
When this fine powder was observed with a scanning electron microscope (SEM), the silica tertiary aggregate particles were not substantially observed, and this was substantially composed of the leaf-like silica secondary particles of the present invention. There was found.
[0199]
When this fine powder was identified by a powder X-ray diffraction spectrum, the main phase of 2θ = 4.9 ° and 26.0 ° corresponding to ASTM card number 16-0380 was characterized as an X-ray diffraction spectrum. In addition to the main peak of Silica-X, peaks corresponding to ASTM card numbers 31-1235 and 37-0386 were observed.
[0200]
The ratio of the peak height at 2θ of 26.0 ° to the peak height at 2θ of 4.9 ° was 1.4.
[0201]
When the morphology of the generated particles was observed with a transmission electron microscope (TEM), the scaly thin primary particles were oriented in parallel with each other between the surfaces, and a plurality of sheets overlapped to form the leaf-like silica secondary particles of the present invention. It was observed that
[0202]
Moreover, when this fine powder was embedded in an epoxy resin, an ultrathin section was prepared with an ultramicrotome, and observed with a transmission electron microscope (TEM), the thickness of the primary particles was as extremely thin as 1 to 10 nm. I understood.
[0203]
The fine powder has a pore volume of 0.12 ml / g and a specific surface area of 65 m, measured by a BET method pore size distribution measuring apparatus (Bell Soap 28 type, manufactured by Bell Japan) ² / G, and a sharp large peak in the mesopore region was observed near 3.6 nm in the pore distribution curve.
Moreover, in the infrared absorption spectrum (Nicoray Japan make, FT-IR510 type | mold) measurement of the said fine powder, 3600-3700cm ^-1 3400-3500cm ^-1 Silanol groups each having one absorption band were observed.
[0204]
In addition, the amount of silanol groups (SiOH) is determined based on the difference between the loss on drying at 120 ° C. for 2 hours and the loss on heating at 1200 ° C. for 3 hours (W mass%). SiOH) = W × 1111.1 (μmol / g), 3650 μmol / g, and 56.2 μmol / m per specific surface area according to the BET method. ² It showed a big value.
[0205]
Regarding heat resistance, no particular change was observed in an observation with a scanning electron microscope at 500 to 1000 ° C. in an air atmosphere.
[0206]
For saturation solubility at 20 ° C. in aqueous acid and alkaline solutions, the dissolved SiO ₂ Concentration is 10% by mass, 0.008% by mass for HCl aqueous solution, 0.006% by mass for ion exchange water, 0.55% by mass for 5% by mass NaOH aqueous solution, It was 0.79 mass% with respect to 10 mass% NaOH aqueous solution. In particular, regarding alkali resistance, for example, the solubility was very small compared to silica gel (in the case of silica gel, the solubility is 6.5% by mass even with respect to 3 wt% NaOH).
[0207]
[Example 5] (Production of slurry-like secondary silica particles of the present invention from the dry powder of Example 1)
[0208]
300 g of the dry fine powder obtained with the medium fluidized bed dryer of Example 1 was added to 1700 g of water to obtain a 15% by mass solid content slurry (average particle size 6.1 μm, viscosity 0.008 Pa · s).
[0209]
Next, this slurry was mixed with a medium stirring bead mill (Shinmaru Enterprises Co., Ltd., Dynomill KDL-PILOT A type (Bessel capacity 1.4 L, diameter 0.5 mm zirconia beads 80% filled)) at a shaft rotation speed of 3400 rpm and a flow rate of 30 L / h. Then, the silica tertiary aggregate particles were crushed and dispersed.
[0210]
The average particle diameter of the fine particles in the slurry after pulverization / dispersion by a Coulter counter was 1.6 μm. Moreover, it was 0.029 Pa * s when the viscosity of this slurry was measured with the B-type viscometer.
[0211]
When the fine particles in the slurry were observed with a scanning electron microscope, it was found that the silica tertiary aggregate particles were not substantially observed and were substantially composed of the leaf-like silica secondary particles of the present invention.
[0212]
[Example 6] (Production of slurry-like secondary silica particles of the present invention from the wet cake of Example 3)
[0213]
1087 g of water was added to 1000 g (solid content concentration: 31.3 mass%) of the wet cake after washing with water filtered by the centrifuge shown in Example 3, and repulped to prepare a silica slurry having a solid content of 15 mass%.
[0214]
In this slurry state, the average particle diameter measured by a Coulter counter was 6.1 μm, and the viscosity measured by a B-type viscometer was 0.010 Pa · s.
[0215]
Next, this slurry was mixed with a medium stirring bead mill (Shinmaru Enterprises Co., Ltd., Dynomill KDL-PILOT A type (Bessel capacity 1.4 L, diameter 0.5 mm zirconia beads 80% filled)) at a shaft rotation speed of 3400 rpm and a flow rate of 30 L / h. Then, the silica tertiary aggregate particles were crushed and dispersed.
[0216]
The average particle size of the fine particles in the slurry after pulverization / dispersion by a Coulter counter was 1.7 μm. Moreover, it was 0.15 Pa * s when the viscosity of this slurry was measured with the B-type viscosity meter.
[0217]
When the fine particles in the slurry were observed with a scanning electron microscope, it was found that the silica tertiary aggregate particles were not substantially observed and were substantially composed of the leaf-like silica secondary particles of the present invention.
[0218]
[Example 7] (Production of slurry-like secondary silica particles of the present invention from the wet cake of Example 2)
[0219]
1220 g of water was added to 1000 g of wet cake (solid content concentration: 33.3% by mass) after washing with water filtered by the centrifuge shown in Example 2, and repulped to prepare a silica slurry having a solid content of 15% by mass.
[0220]
In the state of this slurry, the average particle diameter by a Coulter counter was 6.8 μm, and the viscosity by a B-type viscometer was 0.010 Pa · s.
[0221]
Next, this slurry was mixed with a medium stirring bead mill (Shinmaru Enterprises Co., Ltd., Dynomill KDL-PILOT A type (Bessel capacity 1.4 L, diameter 0.5 mm zirconia beads 80% filled)) at a shaft rotation speed of 3400 rpm and a flow rate of 30 L / h. Then, the silica tertiary aggregate particles were crushed and dispersed.
[0222]
The average particle diameter of the fine particles in the slurry after pulverization / dispersion by a Coulter counter was 1.6 μm. Moreover, it was 0.16 Pa * s when the viscosity of this slurry was measured with the B-type viscometer.
[0223]
When the fine particles in the slurry were observed with a scanning electron microscope, it was found that the silica tertiary aggregate particles were not substantially observed and were substantially composed of the leaf-like silica secondary particles of the present invention.
[0224]
[Example 8] (Silica slurry obtained from Example 4 / Production of secondary silica particles of the present invention using a spray dryer)
[0225]
Water was added to the slurry (solid content concentration 15% by mass) after pulverization and dispersion by the medium stirring bead mill obtained in Example 4, and the slurry concentration was adjusted to a solid content concentration of 3% by mass.
[0226]
The slurry is spray-dried at a slurry supply rate of 5 ml / min, spray pressure of 0.3 MPa (G) and hot air temperature of 200 ° C. using a small spray dryer (manufactured by Yamato Kagaku Co., GA32 type) to obtain a dry fine powder. It was.
[0227]
The average particle diameter of the obtained fine powder by a Coulter counter was 3.7 μm.
When the fine particles in the slurry were observed with a scanning electron microscope, it was found that the number of silica tertiary aggregate particles was extremely small, and substantially consisted of the leaf-like silica secondary particles of the present invention.
[0228]
[Example 9] (Production of secondary silica particles of the present invention by dry pulverization and classification from the silica tertiary aggregate particles obtained in Example 1)
[0229]
The dry powder of silica tertiary aggregate particles obtained in Example 1 is a counter jet mill equipped with both a jet mill for dry grinding and a high-speed rotary classifier for dry classification (100AFG type, manufactured by Hosokawa Micron Corporation, classification) Machine 50ATP type), use compressed air amount 0.69Nm ^Three / Hr, air pressure 0.6 MPa, classifier rotation speed 22000 rpm, powder throughput 210 g / hr were continuously crushed and dispersed.
[0230]
The average particle diameter of the obtained fine particles by a Coulter counter was 2.1 μm. When these fine particles were observed with a scanning electron microscope (SEM), it was found that almost no silica tertiary aggregate particles were observed, and the particles were substantially composed of the secondary silica particles of the present invention.
[0231]
[Example 10] (Coating obtained from curable composition for paint / coating agent comprising silica slurry of Example 4)
[0232]
The slurry (solid content concentration 15% by mass, average particle size 1.6 μm) after the treatment with the medium stirring bead mill of Example 4 was put in a 50 g beaker and sufficiently stirred and mixed with a stirrer.
[0233]
Next, a glass plate (soda lime glass, 70 mm × 150 mm × 2 mm thickness) compliant with JIS K 5400 is prepared, and a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.) is used with a bar coater coating method (JIS K 5400). Then, the slurry was applied to a glass plate and dried at room temperature to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² Met. The appearance of the coating film was smooth and no cracks were observed.
[0234]
Further, a scanning electron micrograph of the fracture surface of the coating film is shown in FIG. From the photograph, the leaf-like silica secondary particles each have an appropriate bend, entangled with each other in the bent state, and a densely overlapping form is observed. Further, the coating film was peeled off using a razor, and the pore structure was measured using a BET method pore distribution measuring device (Nippon Bellthorpe Corp., Bellthorpe 28 type). The pore volume was 0.13 ml / g, specific surface area is 66m ² In the pore distribution curve, a large sharp peak in the mesopore region was observed near 3.6 nm. This is a numerical value close to the pore structure of the leaf-like silica secondary particles shown in Example 4, and is considered to indicate that the leaf-like silica secondary particles are closely overlapped with each other in the formed coating film. . Further, as described above, this coating film has air permeability because of its porous structure.
[0235]
Further, when X-ray diffraction measurement was performed on the surface of the coating film peeled off using a razor, two main peaks corresponding to ASTM Card No. 16-0380 of Silica X, that is, 2θ was 4.9 ° peak height. The ratio of the peak height when 2θ is 26.0 ° is a small value of 0.07, indicating that the crystal grains forming the coating film are oriented.
[0236]
As the evaluation of the coating film, pencil hardness, cross-cut peel test, and water resistance (at room temperature, under water for 24 hours) were measured according to JIS K 5400. The results are shown in Table 1.
[0237]
[Table 1]

[0238]
[Example 11] (Coating obtained from curable composition for paint / coating agent comprising silica slurry of Example 4 (in the case of thick coating))
[0239]
The slurry (solid content concentration 15% by mass, average particle size 1.6 μm) after the treatment with the medium stirring bead mill of Example 4 was put in a 50 g beaker and sufficiently stirred and mixed with a stirrer.
[0240]
Next, prepare a glass plate (soda lime glass, 70 mm x 150 mm x 2 mm thickness) compliant with JIS K 5400, and use a bar coater coating method (JIS K 5400) with a # 120 bar coater (manufactured by Eto Kikai Co., Ltd.). The slurry was applied four times to a glass plate and dried at room temperature to obtain a test piece. The coating amount is 100 g / m in terms of solid content. ² Met.
[0241]
As the evaluation of the coating film, pencil hardness, cross-cut peel test, and water resistance (at room temperature, under water for 24 hours) were measured according to JIS K 5400. The results are shown in Table 1.
[0242]
[Example 12] (Coating obtained from curable composition for paint / coating agent comprising silica slurry of Example 4 (example showing heat resistance))
[0243]
The slurry (solid content concentration 15% by mass, average particle size 1.6 μm) after the treatment with the medium stirring bead mill of Example 4 was put in a 50 g beaker and sufficiently stirred and mixed with a stirrer.
[0244]
Next, a quartz glass plate (100 mm × 100 mm × 2 mm thickness) is prepared, and the slurry is applied to the quartz glass plate by using a bar coater coating method (JIS K 5400) using a # 100 bar coater (manufactured by Eto Instruments Co., Ltd.). After coating and drying at room temperature, the test piece was further baked at 600 ° C. for 1 hour. The coating amount is 20 g / m in terms of solid content. ² Met.
[0245]
As the evaluation of the coating film, pencil hardness, cross-cut peel test, and water resistance (at room temperature, under water for 24 hours) were measured according to JIS K 5400. The results are shown in Table 1. The table shows that this coating film is quite heat resistant.
[0246]
[Example 13] (Coating film obtained from curable composition for paint / coating agent prepared by mixing epoxy-based aqueous resin emulsion with silica slurry of Example 4)
[0247]
Adeka Resin EM0460 (Aqueous emulsion of epoxy resin manufactured by Asahi Denka Kogyo Co., Ltd., solid content concentration: 40% by mass) 9.68 g and 38.70 g of demineralized water were weighed and mixed in a 250 ml plastic bottle by shaking the plastic bottle.
[0248]
Next, 145.40 g of the slurry (solid content 15% by mass) after the treatment with the medium stirring bead mill of Example 4 was weighed, and a 250 ml plastic bottle was shaken until the whole became uniform. After shaking with V-5 type), foaming was slightly observed, and thus a curable composition was obtained by degassing under reduced pressure with an aspirator.
[0249]
Next, prepare a glass plate (soda lime glass, 70 mm x 150 mm x 2 mm thickness) compliant with JIS K 5400, and use a bar coater coating method (JIS K 5400) with a # 120 bar coater (manufactured by Eto Kikai Co., Ltd.). Then, the slurry was applied to a glass plate and dried at room temperature to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² Met. The appearance of the coating film was smooth and no cracks were observed.
[0250]
Here, the mass ratio in solid content of the leaf-like silica secondary particles of Example 4 and the resin emulsion is 85:15.
The coating film was evaluated for pencil hardness, cross-cut peel test and water resistance (at room temperature, under water for 24 hours) in accordance with JIS K 5400. The results are shown in Table 1.
[0251]
[Example 14] (Coating film obtained from curable composition for paint / coating agent prepared by blending silica slurry of Example 4 with acrylic urethane based commercial paint)
[0252]
In a 250 ml plastic bottle, weigh out 5.92 g of aqueous urethane W # 100 (Acrylic urethane resin aqueous emulsion manufactured by Asahi Glass Coat and Resin Co., Ltd., solid content concentration 51 mass%) and 15.60 g of demineralized water. Shake to mix.
[0253]
To this was added caustic soda to the slurry (solid content 15 mass%) treated with the medium stirring bead mill of Example 4 to adjust the pH to 9.4, and 113.3 g was weighed and added to the plastic bottle. After the 250 ml plastic bottle was shaken with a shaker (V-5 type, manufactured by Iwaki Co., Ltd.) until the whole became uniform, foaming was slightly observed. Got.
[0254]
Next, prepare a glass plate (soda lime glass, 70 mm x 150 mm x 2 mm thickness) compliant with JIS K 5400, and use a bar coater coating method (JIS K 5400) with a # 120 bar coater (manufactured by Eto Kikai Co., Ltd.). Then, the slurry was applied to a glass plate and dried at room temperature to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² Met. The appearance of the coating film was smooth and no cracks were observed.
[0255]
Here, the mass ratio in solid content of the leaf-like silica secondary particles of Example 4 and the resin emulsion is 85:15.
The coating film was evaluated for pencil hardness, cross-cut peel test and water resistance (at room temperature, under water for 24 hours) in accordance with JIS K 5400. The results are shown in Table 1.
[0256]
[Example 15] (Coating obtained from curable composition for paint / coating agent in which fluororesin-based commercial paint is blended with silica slurry of Example 4)
[0257]
250 g of the silica slurry (solid content concentration 15% by mass) treated with the medium stirring bead mill of Example 4 was collected in a 250 ml plastic bottle, and 1.25 g of surfactant Ionette S-20 (manufactured by Sanyo Chemical Industries) was added. Then, the plastic bottle was shaken with a shaker (V-5 type, manufactured by Iwaki Co., Ltd.) and mixed to obtain a silica slurry containing a surfactant. Of this, 113.3 g was collected and used for the following tests.
[0258]
Bonfron W # 1500 (Aqueous emulsion of fluororesin resin manufactured by Asahi Glass Coat and Resin Co., Ltd., solid content concentration 51 mass%) 5.92 g and demineralized water 38.70 g were weighed into the 250 ml plastic bottle.
[0259]
After adding 113.3 g of the above-mentioned surfactant-containing silica slurry and 0.015 g of silicone KS-508 (manufactured by Shin-Etsu Chemical Co., Ltd.), shake the 250 ml plastic bottle until the whole becomes uniform. (Iwaki Co., Ltd., V-5 type) was mixed by shaking to obtain a curable composition.
[0260]
In addition, the mass ratio in the solid content of the silica of Example 4 and a resin emulsion is 85:15.
Next, a glass plate (soda lime glass, 70 mm × 150 mm × 2 mm thickness) compliant with JIS K 5400 is prepared, and a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.) is used with a bar coater coating method (JIS K 5400). Then, the slurry was applied to a glass plate and dried at room temperature to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² Met. The appearance of the coating film was smooth and no cracks were observed.
[0261]
As the evaluation of the coating film, pencil hardness, cross-cut peel test, and water resistance (at room temperature, under water for 24 hours) were measured according to JIS K 5400. The results are shown in Table 1.
[0262]
[Example 16] (Coating film obtained from curable composition for paint / coating agent prepared by blending silicon slurry-based commercial paint with silica slurry of Example 4)
[0263]
250 g of the silica slurry (solid content concentration 15% by mass) treated with the medium stirring bead mill of Example 4 was collected in a 250 ml plastic bottle, and 1.25 g of surfactant Ionette S-20 (manufactured by Sanyo Chemical Industries) was added. Then, the plastic bottle was shaken with a shaker (V-5 type, manufactured by Iwaki Co., Ltd.) and mixed to obtain a silica slurry containing a surfactant. Of this, 113.3 g was collected and used for the following tests.
[0264]
In the above 250 ml plastic bottle, 5.59 g of Odefresh Si-100 (manufactured by Nippon Paint Co., Ltd., aqueous emulsion of silicon resin resin, solid content concentration 54 mass%) and 40.0 g of demineralized water were weighed. Next, after adding 113.3 g of the above slurry containing the surfactant and 0.013 g of silicone KS-508 (manufactured by Shin-Etsu Chemical Co., Ltd.), shake the 250 ml plastic bottle until the whole becomes uniform. A curable composition was obtained by mixing with a shaker (V-5, manufactured by Iwaki Co., Ltd.).
In addition, the mass ratio in the solid content of the silica of Example 4 and a resin emulsion is 85:15.
[0265]
Next, a glass plate (soda lime glass, 70 mm × 150 mm × 2 mm thickness) compliant with JIS K 5400 is prepared, and a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.) is used with a bar coater coating method (JIS K 5400). Then, the slurry was applied to a glass plate and dried at room temperature to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² Met. The appearance of the coating film was smooth and no cracks were observed.
[0266]
As the evaluation of the coating film, pencil hardness, cross-cut peel test, and water resistance (at room temperature, under water for 24 hours) were measured according to JIS K 5400. The results are shown in Table 1.
[0267]
[Example 17] (Coating film obtained from curable composition for paint / coating agent prepared by mixing aqueous emulsion of tetrafluoroethylene resin (hereinafter referred to as PTFE) into silica slurry of Example 4)
[0268]
In a 250 ml plastic bottle, 1.8 g of an aqueous PTFE emulsion (product name: Fullon AD1, manufactured by Asahi Glass Co., Ltd., solid content concentration: 55% by mass) was weighed and treated with the medium stirring bead mill of Example 4 to obtain a silica slurry (solid content concentration). (15% by mass) 60 g was added to the above plastic bottle, and the 250 ml plastic bottle was shaken with a shaker (type I-5, model V-5) until the whole became uniform. And mixed and dispersed for 30 minutes.
[0269]
In addition, the mass ratio in the solid content of the silica of Example 4 and PTFE was 90:10.
Next, a glass plate (soda lime glass, 70 mm × 150 mm × 2 mm thickness) compliant with JIS K 5400 is prepared, and a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.) is used with a bar coater coating method (JIS K 5400). The slurry was applied to a glass plate, dried at room temperature, and then heat treated at 380 ° C. for 2 hours to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² Met. The appearance of the coating film was smooth and no cracks were observed.
[0270]
As the evaluation of the coating film, pencil hardness according to JIS K 5400, cross-cut peel test, acid resistance (at room temperature, 24 hours in 5% sulfuric acid), alkali resistance (at room temperature, in 5% aqueous sodium carbonate solution for 24 hours) And water resistance (at room temperature for 24 hours in water), and the results are shown in Table 2.
[0271]
[Table 2]

[0272]
[Example 18] (Coating obtained from curable composition for paint / coating agent in which fluororesin paint (use of non-aqueous solvent) is blended with silica fine powder of Example 8)
[0273]
In a 250 ml plastic bottle, 25 g of fluororesin paint (made by Asahi Glass Co., Ltd., trade name Lumiflon LF-200, solid content concentration 60% by mass), 2.5 g of curing agent (manufactured by Asahi Kasei Co., Ltd., Duranate TPA-100), and 25 g of xylene Weighed.
[0274]
Next, 15 g of fine powder of leaf-like silica secondary particles obtained in Example 8 was added to the plastic bottle, and a 250 ml plastic bottle was shaken until the whole became uniform (Iwaki, Model V-5) Then, the slurry was placed in a tumbler shaker mixer (manufactured by Shinmaru Enterprises, T2C type), and mixed and dispersed for 30 minutes.
[0275]
Next, an iron plate (70 mm × 150 mm × 2 mm thickness) compliant with JIS K 5400 is prepared, and applied to the iron plate using a bar coater coating method (JIS K 5400) using a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.). The slurry was applied and dried at room temperature to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² Met.
[0276]
In addition, the mass ratio in solid content of the leaf-like silica secondary particle of Example 8 and a fluororesin coating material is 46:54.
As the evaluation of the coating film, pencil hardness according to JIS K 5400, cross-cut peel test, acid resistance (at room temperature, 24 hours in 5% sulfuric acid), alkali resistance (at room temperature, in 5% aqueous sodium carbonate solution for 24 hours) And water resistance (at room temperature for 24 hours in water), and the results are shown in Table 2.
[0277]
[Example 19] (Coating obtained from curable composition prepared by mixing silica sol with silica slurry of Example 4)
[0278]
45.34 g of the silica slurry (solid content concentration 15% by mass) treated with the medium stirring bead mill of Example 4 was put in a 50 ml glass bottle, and then colloidal silica (trade name Cataloid SI-30 manufactured by Catalytic Chemical Industry Co., Ltd.) 4 0.0 g was added and shaken to mix evenly to obtain a curable composition.
[0279]
Next, a glass plate (soda lime glass, 70 mm × 150 mm × 2 mm thickness) compliant with JIS K 5400 is prepared, and a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.) is used with a bar coater coating method (JIS K 5400). Then, the slurry was applied to a glass plate and dried at room temperature to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² Met. The appearance of the coating film was smooth and no cracks were observed.
[0280]
In addition, the mass ratio in solid content of the leaf-like silica secondary particle of Example 4 and colloidal silica is 85:15.
The coating film was evaluated for pencil hardness, cross-cut peel test and water resistance (at room temperature, under water for 24 hours) in accordance with JIS K 5400. The results are shown in Table 1.
[0281]
[Example 20] (Hygroscopic coating film obtained from a curable composition obtained by blending silica gel powder in the silica slurry of Example 4)
[0282]
40 g of silica slurry solid content after treatment with the medium stirring bead mill of Example 4 and 66 g of ion exchange water were placed in a 200 ml plastic container and mixed, and then A type silica gel fine powder gel (Dokai Chemical Industries, Ltd.) Manufactured, average particle diameter 4 μm) 54 g was added, and the mixture was shaken and mixed for 10 minutes with a shaker (manufactured by Iwaki Corporation, type V-5) to obtain a curable composition.
[0283]
Next, a glass plate (soda lime glass, 100 mm × 200 mm × 2 mm thickness) compliant with JIS K 5400 is prepared, and using a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.) with a bar coater coating method (JIS K5400). The slurry was applied to a glass plate, dried at room temperature, and further dried at 110 ° C. for 1 hour to obtain a test piece. The coating amount is 100 g / m in terms of solid content. ² Met. The appearance of the coating film was smooth and no cracks were observed.
[0284]
In addition, mass ratio in solid content of the leaf-like silica secondary particle of Example 4 and A-type silica gel fine powder is 10:90.
Since this coating film has a moisture adsorption / desorption function, the moisture adsorption equilibrium is determined in accordance with JIS 0701 by allowing it to stand for 48 hours in a desiccator with a relative humidity adjusted at 25 ° C. to absorb moisture. The equilibrium moisture adsorption rate was determined from the mass increase rate.
[0285]
The equilibrium moisture adsorption rate was calculated based on the mass of the silica coating film (total mass of the leaf-like silica secondary particles and A-type silica gel) after drying the test piece at 180 ° C. for 2 hours. The results are shown in Table 3.
[0286]
[Table 3]

[0287]
[Example 21] (Separation material for thin layer chromatography obtained from a curable composition in which silica gel powder is mixed with silica slurry of Example 4)
[0288]
After 19.5 g of the slurry (solid content concentration 15% by mass) treated with the medium stirring bead mill of Example 4 and 100 g of ion-exchanged water were mixed in a 200 ml plastic container, microspherical silica gel for liquid chromatography (sinuses) 56 g of Sea Chemical Industry, trade name MS gel, EP-DF-7-60A, average particle size 7 μm) is added, and the mixture is shaken and mixed for 10 minutes with a shaker (Iwaki, type V-5). A curable composition was obtained.
[0289]
Next, a glass plate (soda lime glass, 100 mm × 200 mm × 2 mm thickness) is prepared, and is set to a film thickness of 0.5 mm using an applicator (manufactured by Tanizawa Kagaku Co., Ltd.). It was applied to. The coated glass plate was dried at room temperature and further dried at 110 ° C. for 1 hour.
[0290]
In addition, the mass ratio in the solid content of the leaf-like silica secondary particle of Example 4 and the fine spherical silica gel is 5:95.
The appearance of the coating film was smooth and strong without cracks. The coating amount is 200 g / m in terms of solid content. ² The coating thickness was about 250 μm.
[0291]
Using this test piece, the performance as a thin layer chromatography was measured and evaluated according to a conventional method. Separation was performed using a lipophilic system (hexane: chloroform = 1: 1) in the developing tank.
[0292]
The separation sample is a commercially available dye solution (Bayer, Macrolex Green, Macrolex Violet, Hodogaya Chemical Co., SOT Blue, each 0.1% concentration in chloroform), and a capillary is used. Then, it was spotted 15 mm from the lower end of the plate, and the development distance was 150 mm from the spot.
[0293]
The distance of the developing solvent and the distance between the centers of the spots of each sample separated were measured, and the ratio of the distance of each spot to the developing distance of the developing solvent was calculated to obtain the Rf value. The evaluation results are shown in Table 4.
[0294]
[Table 4]

[0295]
[Example 22] (A coating film having an ultraviolet shielding function obtained from a curable composition obtained by blending fine particle titanium oxide with the silica slurry of Example 4)
[0296]
Fluorine resin paint (trade name Lumiflon LF-200, solid content concentration 60 mass%) 25 g, 250 g curing agent (Asahi Kasei Co., Duranate TPA-100) 2.5 g xylene 12.5 g in a 250 ml plastic bottle Next, 3.9 g of fine powder of the leaf-like silica secondary particles obtained in Example 8 and fine particle titanium oxide (Ishihara Sangyo Co., Ltd., TTO-51A, average particle size 0.01 μm, rutile type) 2.1 g is added to the above plastic bottle, and the 250 ml plastic bottle is shaken with a shaker (Iwaki, Model V-5) until the whole becomes uniform, and then the slurry is shaken by a shaker shaker mixer (Shinmaru (T2C type, manufactured by Enterprise) and mixed with shaking for 30 minutes.
[0297]
Next, a quartz glass plate (100 mm × 100 mm × 2 mm thickness) is prepared, and applied to one side of the quartz glass plate by using a bar coater coating method (JIS K 5400) using a # 40 bar coater (manufactured by Eto Kikai Co., Ltd.). The slurry was applied and dried at room temperature to obtain a test piece. The coating amount is 20 g / m in terms of solid content. ² The coating thickness was 30 μm.
[0298]
In addition, the mass ratio in the solid content of a fluororesin coating material, the leaf-like silica secondary particle fine powder of Example 8, and fine particle titanium oxide is 74.5: 16.5: 9.0.
In the coating film evaluation of these test pieces, the pencil hardness was 3H, and the cross-cut peel test evaluation score was 8 points.
[0299]
Similarly, a quartz glass plate (100 mm × 100 mm × 2 mm thickness) is prepared, and applied to one side of the quartz glass plate by using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.) with a bar coater coating method (JIS K 5400). The slurry was applied and dried at room temperature to obtain a test piece. The coating amount is 30 g / m in terms of solid content. ² The coating thickness was 45 μm.
[0300]
Similarly, a quartz glass plate (100 mm × 100 mm × 2 mm thickness) is prepared, and one side of the quartz glass plate is coated with a bar coater (JIS K 5400) using a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.). The slurry was applied to and dried at room temperature to obtain a test piece. The coating amount is 37 g / m in terms of solid content. ² The coating thickness was 55 μm.
[0301]
About each of these test pieces, the transmittance | permeability in each wavelength was measured using the self-recording spectrophotometer (the Hitachi Ltd. make, U-4000 type | mold), and the ultraviolet-ray shielding performance was calculated | required. The evaluation results are shown in Table 5.
[0302]
[Table 5]

[0303]
[Example 23] (Coating film having photooxidation catalyst function obtained from curable composition in which fine particle titanium oxide is blended in silica slurry of Example 4)
[0304]
In a 250 ml plastic bottle, the slurry (solid content concentration 15% by mass) after being treated with the medium stirring bead mill of Example 4 was weighed, and then ultrafine titanium oxide (ST-01, average particle diameter 0.01 μm, manufactured by Ishihara Sangyo Co., Ltd.). , Anatase type) 12.1 g is added to the above plastic bottle, and the 250 ml plastic bottle is shaken with a shaker (model V-5, manufactured by Iwaki Co., Ltd.) until the whole becomes uniform. (T2C type, manufactured by Shinmaru Enterprise Co., Ltd.), and mixed and dispersed for 30 minutes.
[0305]
Next, a glass plate (soda lime glass, 100 mm × 100 mm × 2 mm thickness) is prepared, and by using a bar coater coating method (JIS K 5400), a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.) is used. The slurry was applied on one side, dried at room temperature to obtain a test piece, and then heat treated at 500 ° C. for 1 hour to obtain a test piece.
[0306]
The coating amount is 30 g / m in terms of solid content. ² Met. The pencil hardness of the coating film was B, and the evaluation score of the cross-cut peel test was 10 points.
[0307]
This test piece was immersed in a petri dish (inner diameter: 200 mm, depth: 50 mm) containing 500 ml of a 33.3 mg / L aqueous methanol solution so that the coated surface was below the liquid level, with the coated side facing up. Further, while stirring the liquid with a stirrer, while allowing the air to dissolve from the liquid surface, an ultraviolet lamp (30 W) was irradiated from directly above the liquid surface at a distance of 30 cm from the liquid surface for 60 hours.
[0308]
As a blank for comparison, a glass plate of the same size not coated was used and tested under the same conditions as the test piece.
The COD value in liquid was measured for the methanol aqueous solution after irradiation by the COD measurement method of JIS K 0120. The results are shown in Table 6.
[0309]
[Table 6]

[0310]
[Example 24] (Molded body obtained by wet compression molding (dehydration compression molding) using silica alone in Example 4)
[0311]
The slurry (solid content concentration: 15% by mass) treated with the medium stirring bead mill of Example 4 was evaporated and concentrated under reduced pressure with stirring to prepare a soft wet cake with a solid content concentration of 32.8% by mass.
[0312]
13 g of the wet cake was weighed and filled in a cylinder of a pellet press (inner diameter 20 mm × stroke 50 mm). A filter paper was placed under the cylinder so that it could be dehydrated.
[0313]
A piston was attached and pressurized with a hand press and slowly pressurized from 1.96 MPa to 19.6 MPa to obtain a cylindrical wet pellet (diameter 20 mm, height 10 mm) as a molded body. This was dried at 120 ° C. for 2 hours using a box-type dryer to obtain dry pellets (diameter 20 mm, height 10 mm) having a mass of 4.1 g.
[0314]
The compressive strength of the dried pellet is measured by compressing and destroying the pellet by attaching a push rod (tip diameter 3 mm) to a compressive strength tester (manufactured by Kyushu Maruto Co., Ltd., 980N compressive strength tester). The displacement was converted to a reading load with a micrometer. When 10 pellets were measured and the average value of the compressive load at the time of pellet destruction was determined, it was 710N.
[0315]
[Example 25] (Molded body obtained by dry compression molding using silica alone in Example 8)
3.2 g of the silica dry fine powder of Example 8 was weighed and filled into a cylinder of a pellet press machine (inner diameter 20 mm × stroke 50 mm). A piston was attached, and pressure was applied with a hand press, and the pressure was slowly increased from 1.96 MPa to 19.6 MPa to obtain 3.2 g of pellets (diameter 20 mm, height 10 mm) as a molded body.
[0316]
The compressive strength of the pellet was measured by the same method as in Example 24, and the average value of the compressive load at the time of pellet destruction was 284N.
[0317]
[Example 26] (Molded product having moisture adsorption function by wet compression molding (dehydration compression molding) of silica and A-type silica gel mixture of Example 4)
[0318]
After mixing 2.77 g of the same wet cake as in Example 24 (solid content concentration 32.8 mass%) and A-type silica gel water slurry (solid content concentration 17.8 mass%, average particle diameter 4 μm), It filled in the cylinder of the pellet press machine.
[0319]
A piston was attached, and pressure was applied with a hand press, and the pressure was slowly increased from 1.96 MPa to 19.6 MPa to obtain 5.18 g of wet pellets. This was dried with a box-type dryer at 120 ° C. for 2 hours to obtain 3.2 g of dry pellets (diameter 20 mm, height 10 mm) as a molded body. The compressive strength of the pellet was measured by the same method as in Example 24, and the average value of the compressive load when the pellet was broken was 108N. The mass ratio of the leaf-like silica secondary particles and the A-type silica gel in the pellet is 33.3: 66.7.
[0320]
The moisture adsorption equilibrium value of the dried pellets was measured according to JIS Z 0701. The measurement results are shown in Table 3.
[0321]
[Example 27] (Molded product having water adsorption function by dry compression molding of silica and A-type silica gel mixture of Example 8)
[0322]
Example 8 After mixing 1.1 g of dry fine powder of leaf-like silica secondary particles and 2.1 g of A-type silica gel fine powder (manufactured by Dokai Chemical Industry Co., Ltd., average particle size 4 μm), in the cylinder of the pellet press machine Filled.
[0323]
A piston was attached and pressurized with a hand press and slowly pressurized from 1.96 MPa to 19.6 MPa to obtain wet pellets. This was dried with a box dryer at 120 ° C. for 2 hours to obtain 3.2 g of dry pellets (diameter 20 mm, height 10 mm) as a molded body. The compressive strength of the pellet was measured by the same method as in Example 24, and the average value of the compressive load when the pellet was broken was 88.2N. The mass ratio of the leaf-like silica secondary particles and the A-type silica gel in the pellet is 33.3: 66.7.
[0324]
The moisture adsorption equilibrium value of the dried pellets was measured according to JIS Z 0701. The measurement results are shown in Table 3.
[0325]
【The invention's effect】
The leaf-like silica secondary particles of the present invention have a self-forming property and can form a strong silica film having acid resistance, alkali resistance and heat resistance even at room temperature. As a (binder), it is useful for exterior and interior paints and coating agents for buildings and structures, and also has a thermal function, an optical function, an adsorption function catalytic function (such as a photocatalyst), and a biological function. -It is useful for various applications such as coating agents and paints / coating agents having an aroma generating function.
[Brief description of the drawings]
FIG. 1 is a scanning electron micrograph showing the secondary silica particles of the present invention.
FIG. 2 is a transmission electron micrograph showing the secondary silica particles of the present invention.
FIG. 3 is a scanning electron micrograph showing silica tertiary aggregate particles in the present invention.
FIG. 4 is a scanning electron micrograph of a cross section of a coating film composed of the secondary silica particles of the present invention.
FIG. 5 is a scanning electron micrograph of a cross section of a coating film composed of silica tertiary aggregate particles.

Claims (32)

Silica primary aggregate particles formed by hydrothermal reaction are obtained by crushing, and flake primary particles of silica-like silica and / or silica Y having a thickness of 0.001 to 0.1 μm are bonded to each other. It consists of leaf-like silica secondary particles formed by aligning the planes in parallel and overlapping multiple sheets, and the secondary particles have a thickness of 0.001 to 3 μm, and the leaf-like secondary particles (plate) with respect to the thickness The ratio of the longest length (aspect ratio) is at least 10, and the ratio of the minimum length of the leaf-like secondary particles (plate) to the thickness is at least 2, which has a particle structure of a laminated structure that exists independently of each other. And scaly silica particles characterized by having a self-forming property.  The scaly silica particles according to claim 1, wherein the pore diameter has a sharp peak at 2 to 6 nm in pore distribution measurement by a nitrogen adsorption method (BET) method.  The scaly silica particles according to claim 1 or 2, wherein a main peak in the X-ray diffraction analysis of the silica particles is silica corresponding to silica-X and / or silica-Y.  A curable composition comprising particles of a laminated structure according to any one of claims 1 to 3 and comprising flaky silica particles having self-forming properties and a volatile liquid.  The curable composition according to claim 4, further comprising a low-volatile material that does not substantially volatilize at a temperature at which the volatile liquid volatilizes. The curable composition according to claim 4 or 5 content of scaly silica is 1 to 80 mass% in terms of SiO _2.  The curable composition according to claim 5, wherein the low-volatile material is an organic polymer material or a precursor material that forms an organic polymer material by a polymerization reaction.  The curable composition according to claim 5, wherein the low-volatile substance is a substance having an adsorption and desorption function.  The curable composition according to claim 5, wherein the low-volatile substance is a substance having a catalytic function.  The curable composition according to claim 5, wherein the low-volatile substance is a substance having an optical function.  The curable composition according to claim 5, wherein the low-volatile substance is a metal compound. A leaf-like shape in which flake primary particles of scaly silica obtained by drying and curing a coating film or a molded body of the curable composition according to claim 4 are parallelly aligned with each other and overlap each other. A cured product comprising silica secondary particles, wherein secondary particles are laminated in parallel.  The cured body according to claim 12, further comprising the low-volatile material in the cured body.  14. The cured product according to claim 13, wherein the cured product contains an organic polymer material or a precursor material that forms an organic polymer material by a polymerization reaction.  The hardened | cured material of Claim 13 containing the substance which has an adsorption | suction and desorption function in a hardened | cured material.  The hardened | cured material of Claim 13 containing the substance which has a catalyst function in a hardened | cured material.  The cured body according to claim 13, wherein the cured body contains a substance having an optical function selected from an ultraviolet shielding function, a light selective transmission function, and a fluorescence function.  The cured body according to claim 13, wherein the cured body contains amorphous silicon dioxide different from scale-like silica and / or a metal compound other than silicon dioxide.  The cured body according to claim 15, wherein the substance having an adsorption and desorption function is silica gel.  The cured body according to claim 16, wherein the substance having a catalytic function is titanium oxide.  18. The cured product according to claim 17, wherein the substance having an optical function is one kind or two or more kinds of fine particles selected from the group consisting of titanium oxide, zinc oxide, cerium oxide, iron oxide, and zirconium oxide.  The cured body according to claim 18, wherein the amorphous silicon dioxide and / or the metal compound other than silicon dioxide different from the flaky silica is colloidal particles.  The cured body according to any one of claims 12 to 22, wherein the cured body is a coating film.  The cured product according to any one of claims 12 to 23, wherein the main peak in the X-ray diffraction analysis of the silica particles is silica corresponding to silica-X and / or silica-Y.  In the X-ray diffraction pattern measured on the surface of the cured body of silica-X, the ratio of the peak height at 2θ of 26.0 ° to the peak height at 2θ of 4.9 ° is 0.0 to 0.5. The cured body according to claim 24.  It is a manufacturing method of the flaky silica particle for curable compositions of Claim 4, Comprising: (1) Silica hydrogel or silica sol is hydrothermally treated in the presence of an alkali metal salt, and flaky silica flaky primary particles Scaly silica 3 comprising leaf-like silica secondary particles in which the planes are parallel to each other and overlapped with each other, and tertiary particles having gaps formed by irregularly overlapping the secondary particles three-dimensionally. A step of forming secondary aggregate particles, and (2) supplying the silica tertiary aggregate particles to a wet pulverizer or a dry pulverizer / classifier to pulverize and disperse the tertiary aggregate particles to secondary particles. And having a particle form of a laminated structure composed of secondary particles of leaf-like silica, characterized by comprising a step of forming leaf-like silica particles composed of secondary particles having no tertiary particles, and having a self-forming property Of scaly silica particles Production method. Method for producing scaly silica particles according to claim 26, SiO ₂ concentration using the 15 to 75% by weight of silica hydrogel. While hydrothermally treating the silica hydrogel, the hydrothermal treatment temperature is 150 to 220 ° C., and the total silica / alkali molar ratio (SiO ₂ / Me ₂ O (Me represents an alkali metal) in the treatment liquid) is 4 to 15 mol / mol. The method for producing scaly silica particles according to claim 26 or 27.  The method for producing flaky silica particles according to any one of claims 26 to 28, wherein the pulverization and dispersion of the silica tertiary aggregate particles are performed using a wet pulverizer.  30. The method for producing scale-like silica particles according to claim 29, wherein the silica tertiary aggregate particles are crushed and dispersed using a high-speed mechanical stirring wet pulverizer using medium beads.  29. The method according to any one of claims 26 to 28, wherein the drying is carried out continuously by using a combination of a jet mill and a dry classifier as a dry pulverizing / classifying machine for pulverizing and dispersing the dry powder of silica tertiary aggregate particles. A method for producing scaly silica particles.  Use of the scaly silica particles having the particle form of the laminated structure according to any one of claims 1 to 3 and having self-forming properties as a binder for the silica gel fine particles, A separation material for thin layer chromatography, wherein a coating film containing scale-like silica particles is formed.

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