JP3728215B2 - Aluminum silicate - Google Patents
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Description
【０００１】
【産業上の利用分野】
本発明は、紙の填料剤として特に好適に使用される平均粒子径を持ち、高い吸油量と高い不透明性を兼ね備えた水和珪酸系填料、例えば、水和珪酸アルミニウムおよびその製造方法に関する。
【０００２】
【従来の技術】
紙の高品質化には、水和珪酸系填料（水和珪酸、水和珪酸塩）が紙用填料して大きな役割を担っている。すなわち、製紙過程で水和珪酸系填料をパルプ中に添加分散すると、紙質が軽量化すると共に、印刷面のインクを効果的に吸収し、裏面ヘインクを通過させない働き（以下、「裏抜け防止効果」という）をするため、製紙工程での重要な添加物質の一つに位置付けられている。しかし、近時、紙質の一層の高品質化とパルプ原料の低減化を図るため、紙填料用水和珪酸系填料に対するより高度な性能改善が望まれている。特に最近は紙の軽量化が望まれるようになり、その分用紙不透明度、裏抜けを維持することは難しくなってきている。
【０００３】
ここで、裏抜け防止効果を高くする填料に求められるのは、印刷時のインキ成分を吸収する能力（吸油量）および紙の不透明性を高くする能力（比散乱係数）であり、これらを兼ね備えることが望ましい。
水和珪酸系填料はその吸油量の高さのため裏抜け防止効果が高く、特に新聞紙用填料として多用されてきている。
【０００４】
従来、水和珪酸系填料の工業的な製造技術としては、珪酸ソーダを鉱酸で中和する方法が典型的技術として知られているが、その改良手段についても古くから数多くの提案がなされている。例えば、特公昭３８−１７６５１号公報には鉱酸を２段階に分割添加して中和する方法、特公昭５１−２５２３５号公報には多段階中和法が開示されており、特公昭５２−２８７５４号公報および特公昭５２−２８７５５号公報には、反応させる珪酸ソーダと硫酸の濃度、硫酸の添加速度などを制御する方法が詳述されている。また、特開昭５３−８０３９７号公報には珪酸ソーダ希釈液に予め硫酸ナトリウムを添加してから中和反応を行う方法が記載されている。
【０００５】
これらの方法による反応の制御を介して、吸油量や細孔容積の大きい水和珪酸が得られるようになり、紙の裏抜け防止効果は相当に向上したが、得られる水和珪酸は比較的粒子径が大きく、粒度分布が広くて粗粒を多く含有するため、粒子性状に問題があった。このため、粗粒を含まない微粒子性状の水和珪酸を得る手段が盛んに開発されている。
【０００６】
例えば、特開昭６１−１７４１５号公報、特開昭６１−１４１７６７号公報、特開平５−１７８６０６号公報、特開平５−３０１７０７号公報等には、反応終了後のスラリーを湿式粉砕する方法が記載されている。特開昭６０−６５７１３号公報では、鉱酸を２段階に分割して中和する場合に第１段添加後スラリーと反応終了スラリーを２回湿式粉砕する方法が提案されている。これらの方法によれば、反応終了スラリーを粉砕する過程で粗粒分が減少し、裏抜け防止効果と併せて粗粒子が印刷時に紙から剥落する現象（粉落ち）を防止する効果がもたらされるとしている。
【０００７】
しかし、特開昭６１−１４１７６７号公報に示されているような反応終了スラリーを湿式粉砕する方法では、粉砕後における水和珪酸の粒度分布が微粒子側へ偏るため、過度の粉砕を行うと紙中への填料歩留まりが悪くなり、同時に水和珪酸の高構造が破壊されて細孔容積（吸油性）も小さくなる欠点があり、紙の裏抜け防止効果が低くなり好ましくない。そこで、特許公報2908253では、その製造プロセス中の珪酸析出工程で徹底的に粉砕処理をすることで、微粒子の生成が少なく、粗粒分を減らすように平均粒子径を小さく出来るため、紙に内添する場合に填料歩留まりを大きく阻害せず、また印刷時に填料の剥離（粉落ち）を少なくすることが可能であること、またこの方法では平均粒子径を小さくしても吸油量低下を抑制出来るために高い吸油量を維持でき、かつ粒子径が小さいために不透明性が高い、裏抜け防止効果の大きい水和珪酸系填料の製造方法が記載されている。
【０００８】
一方、上述したように裏抜け防止効果を高くするには、吸油量の他に填料配合により紙の不透明度をさらに上げる方法がある。水和和珪酸系填料により紙の不透明度を上げる方法としては、填料の平均粒子径を小さくする方法の他に、特開平6-166987に記載されるように、水和珪酸に微細な不定形金属化合物（マグネシウム）を含有させる方法が記載されている。これは、珪酸ソーダに硫酸を分割添加する方法において、硫酸の一部に酸性金属硫酸塩（硫酸マグネシウム）を代替して反応させる方法であり、不定形金属化合物含有量（１〜２０重量％）が増えるに従い、紙の不透明度を上げる効果が高くなる。しかしながら、この金属含有量が増えるに従い、逆に吸油量は低くなっている。従って、水和珪酸から金属化合物含有による水和珪酸塩化で、紙の不透明度を上げる填料の比散乱係数は上げることが出来るが、もう一つ、裏抜け防止効果に重要な吸油量を阻害してしまう。印刷時の粉落ちが少ないように好適な粒子径を持ち、高い紙の不透明性、裏抜け防止効果を持つために高い吸油性、および高い比散乱係数をバランス良く持つ水和珪酸系填料を製造できれば、今までに無い高性能な填料となることに注視し、本検討を行った。
【０００９】
【発明が解決しようとする課題】
本発明者らは、水和珪酸系填料のうち、水和珪酸は吸油量が高いが、比散乱係数は水和珪酸塩より低く、水和珪酸塩は不定形金属化合物含有により、比散乱係数を上げることが可能であるが、吸油量は逆に珪酸塩化で落ちる点に関し、この吸油量低下が無いように珪酸塩化する方法について検討した。すなわち、水和珪酸系填料において、紙用填料として好適な平均粒子径を有し、紙の不透明度を上げる能力である比散乱係数が大きく、かつ吸油量を高いレベルで維持できる水和珪酸系填料の製造法に関する。
従って、本発明の目的は、紙に内添した場合、粉落ちが少なく、高い不透明性、また裏抜け防止効果の高い水和珪酸塩填料およびその製造方法を提供することにある。
【００１０】
【課題を解決するための手段】
上記の目的を達成するための本発明による水和珪酸塩填料は、特許公報2908253に記載される珪酸ソーダ水溶液に鉱酸（硫酸）を分割添加し、その製造プロセス中の珪酸析出工程で最終的に得られる粒径が１〜１５μｍ、好ましくは、３〜１５μｍになるように湿式粉砕処理をすることによる水和珪酸の製造方法において、鉱酸（硫酸）の一部を酸性金属塩水溶液に代替して反応させ、水和珪酸塩を製造することを特徴とする。ここで、酸性金属塩水溶液を構成する金属元素として、例えばマグネシウム、カルシウム、ストロンチウム、バリウムなどのアルカリ土類金属元素、あるいはチタン、ジルコニウム、ニッケル、鉄、アルミニウム等が挙げられる。この酸性金属塩水溶液としては酸性金属硫酸塩が挙げられ、特に硫酸アルミニウムが好ましい。この製造方法について鋭意検討した結果、三工程に分けて酸を分割添加する際のいずれか一つ以上の工程に、鉱酸（硫酸）の代りに珪酸ソーダ中和当量の５〜６０重量％に相当する酸性金属塩水溶液（硫酸アルミニウム）を使用し、その他は鉱酸（硫酸）により中和することを特徴とすることで、水和珪酸に近い裏抜け性能を発揮するような吸油量レベルを維持し、また珪酸塩化により比散乱係数が高くなるという、その両特徴を兼備出来ることを見出し、本発明をするに至った。ここで酸の添加については、３工程が好ましいが、初期の珪酸分析出工程に徹底的な粉砕工程を行うことが出来れば、酸の添加については、３工程である必要はない。ただし、あまりに多段では効率が悪くなるので、適正な回数を選択する必要がある。なお、歩留まりを考慮するとその微細な不定形金属化合物の含有量が、酸化物換算で０．５〜８重量％（対ＳｉＯ2重量％ 蛍光Ｘ線分析装置オックスフォードＥＤ２０００型による測定）となる。それは、中和相当量の５〜６０重量％である。その製造される水和珪酸塩（珪酸アルミニウム）の具体的な特性は、平均粒子径がレーザー法による測定値で1〜１５μｍ、好ましくは、３〜１５μｍ、吸油量が２００〜３５０ml/100g 、かつ紙に内添填料として配合し、紙の不透明性を向上させる能力を示す比散乱係数が３００〜４５０ｍ2/kgであることを特徴とする。
【００１１】
本発明における水和珪酸塩填料（珪酸アルミニウム）の各特性値は、下記の測定方法により得られた値を用いるものとする。(1) 吸油量；ＪＩＳ Ｋ５１０１の方法による
（2）粒度分布測定（レーザー法）：水和珪酸の試料スラリーを（分散剤ヘキサメタリン酸ソーダ０．２重量％を添加した）純水中で滴下混合して均一分散体とし、レーザー法粒度測定機〔使用機器：マルバーン社製マスターサイザーＳ型）を使用して粒度測定する。（3）填料の比散乱係数の測定：熊谷理機工業（株）製の配向性抄紙機により、抄紙原料としてＮＹＫＰ（半晒しＫＰ）：ＴＭＰ：ＧＰ：ＤＩＰ＝２０：３０：２０：３０の混合比率のパルプスラリーを用い、各実施例において得られた填料スラリーを填料として、その添加率を対パルプ２、５、８重量％として坪量４０g/ｍ2になるように抄造して、ＪＩＳ Ｐ８２０９に記載される方法のプレス条件により脱水後、シリンダードライヤーにて乾燥し、各添加率のシートサンプルを作製した。このシートサンプルをハンター反射率計により緑色フィルターを用いて、黒色標準板を裏当てした時の１枚のシートの反射率をＲ0、同様に標準白色板を裏当てした時の反射率（Ｒ0.89）を測定し、ハンター不透明度（JIS P 8138）算出して、さらに、Kubelka-Munk式に従って各シートサンプルの比散乱係数を算出した。一方、各シートサンプルを５７５℃にて焼成し、残さ分を灰分量として算出した。各シートの灰分量から填料を無添加で同様に抄造したシートサンプルの灰分量を減じて、サンプルの実際に充填された填料量を算出した。この各填料量と各シートの比散乱係数から填料分100重量％とした時の比散乱係数を算出し、填料の比散乱係数とした。
【００１２】
上記したように、本発明に係る水和珪酸塩（珪酸アルミニウム）は、反応第１工程中の徹底した粉砕処理、即ち、最終的に得られる粒径が1〜１５μｍ、好ましくは、３〜１５μｍになるように湿式粉砕処理により、吸油量が大きく低下せずに高いレベルの吸油量、および紙用填料として好適な範囲の平均粒子径を持ち、さらに比散乱係数が高いところに特徴があり、紙の填料として不透明度を向上させ、特に高い裏抜け防止効果をもつ好ましい填料となっている。
【００１３】
上記の粒子性状を備える本発明の水和珪酸塩填料（珪酸アルミニウム）は、珪酸ソーダ水溶液に鉱酸を添加して中和反応により水和珪酸を製造する方法において、シリカ濃度がＳｉＯ2 として６〜１０重量％の珪酸ソーダに中和当量の３０〜５０重量％に相当する量の鉱酸（硫酸）を７０℃以上で反応系の沸点以下の温度において添加した後、熟成時間内に強力剪断力に基づく徹底的な湿式粉砕処理、即ち、最終的に得られる粒径が1〜１５μｍ、好ましくは、３〜１５μｍになるように湿式粉砕処理を施す第１工程、次いで前工程の温度以上の温度において実質的な残量の鉱酸（硫酸）を添加し、熟成してほぼ全量のシリカを析出させる粉砕処理を行わない第２工程、更に鉱酸を添加してスラリーのｐＨを７〜3、好ましくは、５〜３の範囲に調整する第３工程とからなる特許公報2908253に記載されるプロセスによる製造方法において、第１工程〜第３工程のいずれか一つ以上の工程に、酸性金属塩水溶液（硫酸アルミニウム）を添加する。ここで、添加する酸性金属塩水溶液（硫酸アルミニウム）の適正な添加量は、各工程により異なり、また好ましくは第２〜第３工程での添加が良い。さらに、酸性金属塩水溶液（硫酸アルミニウム）による中和量を６０重量％より多くすると、吸油性の低下が大きくなり、いったん上昇した比散乱係数も減じる方向になり好ましくない。酸性金属塩水溶液（硫酸アルミニウム）による中和以外は鉱酸（硫酸）で中和することにより製造される。
【００１４】
なお、各工程での中和率は、第１工程で珪酸ソーダの中和当量の３５〜５０重量％に相当する量の範囲、第２工程は第１工程添加分と積算して中和率が８０〜９５重量％となるように制御することが好ましく、第３工程は残りの５〜２０重量％程度である。酸性金属塩（硫酸アルミニウム）の適正添加量は第１工程で、珪酸ソーダ中和相当量の５〜４０重量％、第２工程で５〜４５重量％、第３工程で５〜２０重量％であり、酸性金属塩（硫酸アルミニウム）による中和量は６０重量％を越えない範囲である。これらは、酸性金属塩の添加量が多くなるに従い、製造される填料の比散乱係数は高くなる傾向にあるが、一方、吸油量が低くなるためその添加量、添加時期を適正化する必要があるからである。
【００１５】
第１工程は、珪酸ソーダ水溶液を濃度調節して加熱し、第１段の鉱酸を添加して湿式粉砕と熟成を行う工程であるが、鉱酸の添加直後から徹底的な粉砕処理、即ち、最終的に得られる粒径が1〜１５μｍ、好ましくは、３〜１５μｍになるように湿式粉砕処理を行う。本検討の結果、この工程で鉱酸（硫酸）の代りに酸性金属塩水溶液（硫酸アルミニウム）を添加すると、製造される填料の比散乱係数は上昇するが、吸油量低下が起き易いことが確認された。このため、第１工程に酸性金属塩水溶液を添加する場合には、その添加量を中和相当量の４０重量％以下にすることが望ましい。この理由は明白でないが、電子顕微鏡観察の結果、第１工程で酸性金属塩水溶液添加により析出する金属化合物を含むシリケートの一次粒子が大きくなり、その後の高次凝集体の細孔容量が小さくなるためと思われる吸油量の低下が大きく、４０重量％を超える量を添加すると、一度上昇した填料の比散乱係数が逆に減少してくるので、これ以上の添加は望ましくない。第２工程は、実質的な残量の鉱酸を第２段として分割添加してほぼ全量のシリカを析出させ、第１工程で析出したシリカ粒子の連結を強化する工程であり、この段階で酸性金属塩水溶液を添加する場合には、酸性金属塩水溶液（硫酸アルミニウム）の添加量が４５重量％までであれば、吸油量の低下を少なく珪酸塩化することが可能であることが確認された。第３工程は、第２工程に引続き更に鉱酸を添加して、スラリーのｐＨを７〜３、好ましくは、５〜３の範囲に調整する工程であり、ここでの鉱酸の添加は、専ら反応系のｐＨの調整にある。しかし驚くべきことにこの第３工程に酸性金属塩水溶液（硫酸アルミニウム）を添加しても、大幅な比散乱係数増加効果が得られ、また吸油量低下も小さい。
【００１６】
第１工程の湿式粉砕に用いる粉砕機としては、特許公報2908253に記載されるボールミル、ロッドミル等の広義のボールミルや、タワーミル、アトライター、セイトリーミル、サンドグラインダー、アニューラミル等の媒体撹拌式粉砕機、コロイドミル、ホモミキサー、インラインミル等の高速回転粉砕機などが挙げられる。本発明で析出するシリカあるいはシリケート粒子は非常に微細であり、特に第１工程で析出するシリカは粉砕され易いため、前記の粉砕機のほか分散機や乳化機の類で粉砕することもできるから、これらを粉砕機と組み合わせて使用しても差し支えない。
【００１７】
なお、第３工程で得られた水和珪酸塩（珪酸アルミニウム）には、副生した硫酸ソーダが混入していることがあるため、濾過、水洗およびリパルプ処理を施すことが好ましい。
【００１８】
【発明の実施の形態】
本発明に係る水和珪酸塩填料は、平均粒子径がレーザー法による測定値で1〜１５μｍ、好ましくは、３〜１５μｍ、吸油量が２００〜３５０ml/100g、かつ紙に内添填料として配合し、紙の不透明性を向上させる能力を示す比散乱係数が３００〜４５０ｍ2/kgであることを特徴とし、特に紙の填料として適用した際に軽量化と高不透明、高白色度性、優れた裏抜け防止効果を発揮する。また、反応中の徹底した粉砕処理により、粗粒子が少なく平均粒径が小さくなっているため、内添された紙の印刷時において粉落ちが少ない効果も持つ。
以上、特許公報2908253に記載される水和珪酸製造方法において、一部酸性金属塩（硫酸アルミニウム）を鉱酸（硫酸）の代りに、適性量、適性添加時期で使用することによる珪酸塩化で、従来の水和珪酸塩に比較し、吸油量、比散乱係数を高いレベルでバランスすることが可能となった。
【００１９】
【実施例】
以下、本発明の実施例を比較例と対比して具体的に説明する。なお、水和珪酸系填料の特性評価（吸油量、平均粒子径、填料の比散乱係数）は上述した方法で実施した。また、紙の裏抜け防止効果および填料歩留りの測定は、次の方法によった。
【００２０】
紙の裏抜け防止効果の測定；熊谷理機工業（株）製の配向性抄紙機により、抄紙原料としてＮＹＫＰ（半晒しＮＫＰ）：ＴＭＰ：ＧＰ：ＤＩＰ＝２０：３０：２０：３０の混合比率のパルプスラリーを用い、各実施例において得られた填料スラリーを填料として、その添加率を対パルプ２、５、８重量％で坪量４０g/ｍ2となるように抄造して、プレスにより脱水後、シリンダードライヤーにて乾燥し、シートサンプルを作製した。このシートサンプルにツボ用新聞インキ〔東洋インキ（株）New King HL墨〕を用いてＲＩテスト印刷機によりインキ盛量（0.6ml）にて第１回目の片面印刷を施した。その後、残ったインキにて別に用意した試料に第２回印刷を実施した。同様に第３回、第４回と刷り減らしにより印刷濃度を変えて印刷を実施した。印刷試料を２３℃、５０重量％ＲＨの雰囲気に２４時間放置後、マクベス反射濃度計で、印刷した裏面の反射率を測定し、各印刷濃度における裏抜け値を次式により（印刷後不透明度）を算出した。裏抜け値＝（印刷裏面の反射率／未印刷の裏面の反射率）×１００(重量％) ４水準の印刷濃度での裏抜け値から、マクベス反射濃度計での印刷濃度が１．０５の時の裏抜け値を算出した。従って、記載する裏抜け値とは印刷濃度が１．０５で印刷された時の値を示す。
【００２１】
実施例１
(1)第１工程（中和率４０％）；反応容器（２００リットル）中で市販の３号珪酸ソーダ(SiO2:20.0重量％、Na2O:9.5重量％)を水で希釈し、ＳｉＯ2 として６．７重量％の希釈珪酸ソーダ溶液２００リットルを調製した。この珪酸ソーダ溶液を８５℃に加熱したのち、中和当量の１０重量％に相当する量の硫酸アルミニウム（Ａｌ2Ｏ3分として濃度8重量％、以下、バンドと省略）を２００ｇ/分の滴下速度で、粗大ゲルが発生しない十分な強撹拌下で添加し、その後、中和当量の３０重量％に相当する量の硫酸（濃度９８重量％）を同様に添加した。添加終了後、得られた部分中和液を攪拌下で熟成処理を行うと同時に、縦形サンドグラインダー（容量２ガロン、直径１ｍｍガラスビーズ充填率７０重量％）により（粒径７μｍを目標に）循環粉砕処理した。この熟成、粉砕処理を３時間行った。
【００２２】
(2)第２工程（中和率４０％）；次いで、スラリー温度を９０℃に昇温し、第１工程と同濃度の硫酸を第１工程同様の条件で、中和当量の８０重量％まで添加し、攪拌下で３２分間熟成した。(3)第３工程（中和率２０％）；引き続き、熟成後のスラリーに同濃度の硫酸を７６ｇ/分の添加速度で同様に添加し、スラリーｐＨを６に調節した。(4)性能評価；第３工程終了後のスラリーを濾過、水洗し、純水にリパルプして水和珪酸スラリーを回収した。得られたスラリーの平均粒子径を測定し、また填料として、上記に示した方法で抄紙し、填料の比散乱係数、裏抜け防止効果および填料歩留りの評価を行った。また、スラリーを濾過し、エタノール中に固形分１０重量％になるよう溶解し再度濾過し、これを１０５℃にて乾燥して吸油量を測定した。その結果を適用した変動条件と対比させて表１に示した。
【００２３】
実施例２
第１工程の中和処理に、中和当量の２０重量％に相当する量のバンドを２００ｇ/分の滴下速度で添加し、残りは硫酸を使用した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００２４】
実施例３
第１工程の中和処理に、中和当量の３０重量％に相当する量のバンドを２００ｇ/分の滴下速度で添加し、残りは硫酸を使用した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００２５】
実施例４
第１工程の中和処理に、中和当量の４０重量％に相当する量のバンドを２００ｇ/分の滴下速度で添加し、残りは硫酸を使用した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００２６】
実施例５
第１工程の中和処理に中和相当量の４０重量％の硫酸を使用し、また第２工程の中和処理のうち、中和当量の１０重量％に相当する量のバンドを２００ｇ/分の滴下速度で添加し、残りは硫酸を使用した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００２７】
実施例６
第１工程の中和処理に中和相当量の４０重量％の硫酸を使用し、また第２工程の中和処理のうち、中和当量の２０重量％に相当する量のバンドを２００ｇ/分の滴下速度で添加し、残りは硫酸を使用した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００２８】
実施例７
第１工程の中和処理に中和相当量の４０重量％の硫酸を使用し、また第２工程の中和処理のうち、中和当量の４０重量％すべてに相当する量のバンドを２００ｇ/分の滴下速度で添加し、残りは硫酸を使用した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００２９】
実施例８
第３工程の中和処理に、中和当量の１０重量％に相当する量のバンドを２００ｇ/分の滴下速度で添加し、その他はすべての中和について硫酸を使用した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。なお、第３工程での硫酸添加は、７６g/分とした。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００３０】
実施例９
第１、第２工程すべてで硫酸を添加し、第３工程の中和当量２０重量％に硫酸は使用せず、すべてバンドを使用し２００ｇ/分の滴下速度で添加した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００３１】
実施例１０
第１工程の中和当量４０重量％すべてに硫酸は使用せず、バンドを２００ｇ/分の滴下速度で添加し、さらに第２工程の中和当量４０重量％のうち、２０重量％分を硫酸バンド２００ｇ／分で添加し中和した後、残りの２０重量％分を同様に硫酸中和した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表１に併載した。
【００３２】
比較例１
第１、２、３工程すべてで、バンドは使用せず、中和相当量１００重量％分すべてにおいて硫酸を使用した以外は実施例１と同一条件により水和珪酸スラリーを製造した。得られたスラリーにつき、実施例１と同様に物性を測定評価し、結果を表２に併載した。
【００３３】
比較例２
第１、第２、第３工程すべてで、硫酸を使用せず、中和相当量１００重量％のバンドを使用した以外は実施例１と同一条件により水和珪酸塩（珪酸アルミニウム）スラリーを製造した。得られたスラリーにつき実施例１と同様に物性を測定評価し、その結果を表２に併載した。
【００３４】
比較例３
市販の水和珪酸塩であるローディアジャパン社Tixolex１７（珪酸アルミニウム塩）を水に分散し、１０重量％濃度スラリーを作成し、得られたスラリーにつき実施例１と同様に物性を測定評価し、その結果を表２に併載した。
【００３５】
比較例４
市販の水和珪酸塩である米国J．M Huber社HYDREX‐P（珪酸マグネシウム塩）を水に分散し、１０重量％濃度スラリーを作成し、得られたスラリーにつき実施例１と同様に物性を測定評価し、その結果を表２に併載した。
【００３６】
【表１】
【表２】
表１の結果から、本発明による水和珪酸塩（珪酸アルミニウム）は高いレベルでの比散乱係数、吸油量をバランス良く持つため、紙の不透明度、白色度が高く、かつ裏抜け防止効果も高いことが分かる。市販の水和珪酸塩である比較例３、４では吸油量が低く、裏抜け防止効果が低くなっている。珪酸塩化しても吸油量の低下が少なくできる理由は明確でないが、第１工程での徹底した粉砕効果が影響していると思われる。
また、比較例２で分かるように硫酸アルミニウムによる中和量が多くなると、珪酸塩化により高くなった比散乱係数が逆に下がり、かつ吸油量低下も大きくなってくるので、硫酸アルミニウムの添加量は６０重量％以下であることが必要であり、すなわち金属元素含有量（酸化物換算 対ＳｉＯ2重量％）を適性に保つことが必要である。
【００３９】
【発明の効果】
以上のとおり、本発明による水和珪酸塩（珪酸アルミニウム）は、高いレベルでの比散乱係数、吸油量をバランス良く持つため、紙の不透明度が高く、かつ裏抜けも防止効果も高い填料であることが分かる。また、本発明に係る製造方法に従えば前記高性能の紙填料用水和珪酸を効率よく工業生産することが可能となる。したがって、製紙工業に資するところ極めて大である。なお、本発明の水和珪酸は紙填料用のほか、塗工紙用のフィラーとしても、その高い比散乱係数のために有用である。[0001]
[Industrial application fields]
The present invention relates to a hydrated silicate filler having an average particle diameter particularly suitably used as a filler for paper, and having both a high oil absorption and high opacity, for example, hydrated aluminum silicate and a method for producing the same.
[0002]
[Prior art]
Hydrated silicic acid based fillers (hydrated silicic acid, hydrated silicates) play a major role as paper fillers in improving the quality of paper. In other words, when hydrated silicate filler is added and dispersed in the pulp during the papermaking process, the paper quality is reduced, the ink on the printed surface is absorbed effectively, and the ink does not pass through the back surface (hereinafter referred to as the “through-through prevention effect”). It is positioned as one of the important additive substances in the papermaking process. However, in recent years, in order to further improve the quality of paper and reduce pulp raw materials, higher performance improvement over hydrated silicate filler for paper filler is desired. In recent years, in particular, it has been desired to reduce the weight of paper, and accordingly, it has become difficult to maintain paper opacity and back-through.
[0003]
Here, what is required of a filler that enhances the effect of preventing back-through is an ability to absorb ink components during printing (oil absorption amount) and an ability to increase the opacity of paper (specific scattering coefficient). It is desirable.
Hydrated silicic acid-based fillers have a high effect of preventing slip-through due to their high oil absorption, and have been frequently used particularly as newspaper fillers.
[0004]
Conventionally, as a typical technique for industrial production of hydrated silicate fillers, a method of neutralizing sodium silicate with mineral acid has been known as a typical technique. However, many proposals have been made for improvement means for a long time. Yes. For example, Japanese Patent Publication No. 38-17651 discloses a method of neutralizing by adding a mineral acid in two stages, and Japanese Patent Publication No. 51-25235 discloses a multi-stage neutralization method. Japanese Patent No. 28754 and Japanese Patent Publication No. 52-28755 detail a method for controlling the concentrations of sodium silicate and sulfuric acid to be reacted, the addition rate of sulfuric acid, and the like. Japanese Patent Laid-Open No. 53-80397 describes a method in which sodium sulfate is added in advance to a dilute solution of sodium silicate and then a neutralization reaction is performed.
[0005]
Through control of the reaction by these methods, hydrated silicic acid having a large oil absorption amount and pore volume can be obtained, and the effect of preventing paper breakthrough has been considerably improved. Since the particle size is large, the particle size distribution is wide, and many coarse particles are contained, there is a problem in the particle properties. For this reason, means for obtaining hydrated silicic acid in the form of fine particles not containing coarse particles has been actively developed.
[0006]
For example, JP-A-61-17415, JP-A-61-141767, JP-A-5-178606, JP-A-5-301707 and the like disclose a method of wet-pulverizing a slurry after completion of the reaction. Has been described. Japanese Patent Application Laid-Open No. 60-65713 proposes a method of wet pulverizing the slurry after the first stage addition and the slurry after the reaction twice when neutralizing the mineral acid in two stages. According to these methods, the coarse particles are reduced in the process of pulverizing the reaction-finished slurry, and the effect of preventing the phenomenon that the coarse particles are peeled off from the paper at the time of printing (powder falling) together with the effect of preventing the back-through. It is said.
[0007]
However, in the method of wet pulverizing the reaction-finished slurry as disclosed in JP-A-61-141767, the particle size distribution of the hydrated silicic acid after the pulverization is biased toward the fine particles side. There is a disadvantage that the yield of the filler into the inside deteriorates, and at the same time, the high structure of hydrated silicic acid is destroyed and the pore volume (oil absorption) is also reduced. Therefore, in Japanese Patent Publication No. 2908253, by thoroughly pulverizing in the silicic acid precipitation step in the manufacturing process, the generation of fine particles is small, and the average particle size can be reduced so as to reduce coarse particles. When adding, it does not significantly impair the filler yield, and it is possible to reduce the peeling (pouring) of the filler during printing, and this method can suppress the decrease in the oil absorption even if the average particle size is reduced. Therefore, a method for producing a hydrated silicate-based filler that can maintain a high oil absorption amount, has high opacity because of its small particle diameter, and has a large effect of preventing see-through is described.
[0008]
On the other hand, as described above, there is a method for further increasing the opacity of the paper by blending a filler in addition to the oil absorption amount in order to increase the effect of preventing the breakthrough. As a method of increasing the opacity of paper with a hydrated silicate filler, in addition to the method of reducing the average particle size of the filler, as described in JP-A-6-166987, fine amorphous particles are added to hydrated silicate. A method of containing a metal compound (magnesium) is described. This is a method in which sulfuric acid is dividedly added to sodium silicate, in which acid metal sulfate (magnesium sulfate) is reacted instead of part of sulfuric acid, and the amorphous metal compound content (1 to 20% by weight) As the value increases, the effect of increasing the opacity of the paper increases. However, as the metal content increases, the oil absorption decreases. Therefore, hydrated silicification from hydrated silicic acid can increase the specific scattering coefficient of the filler, which increases the opacity of the paper, but it also inhibits the oil absorption, which is important for the anti-through-through effect. End up. Produces a hydrated silicic acid-based filler that has a suitable particle size so that there is little powder falling off during printing, high paper opacity, high oil absorption to prevent back-through, and a high specific scattering coefficient in a good balance. If possible, we focused on the fact that it would be an unprecedented high-performance filler and conducted this study.
[0009]
[Problems to be solved by the invention]
Among the hydrated siliceous fillers, the present inventors have high oil absorption, but the specific scattering coefficient is lower than that of the hydrated silicate, and the hydrated silicate contains an amorphous metal compound. However, the method of silicifying the oil so that there is no decrease in the amount of oil absorption was studied. That is, in the hydrated silicate-based filler, the hydrated silicate system has an average particle size suitable as a paper filler, a large specific scattering coefficient that is an ability to increase the opacity of paper, and a high level of oil absorption. The present invention relates to a filler manufacturing method.
Accordingly, an object of the present invention is to provide a hydrated silicate filler having a low powder fall, high opacity, and high anti-through-through effect when internally added to paper, and a method for producing the same.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the hydrated silicate filler according to the present invention is obtained by dividing a mineral acid (sulfuric acid) into a sodium silicate aqueous solution described in Patent Publication 2908253, and finally in a silicic acid precipitation step in the production process. In the method for producing hydrated silicic acid by wet-grinding so that the particle size obtained is 1 to 15 μm, preferably 3 to 15 μm, a part of the mineral acid (sulfuric acid) is replaced with an aqueous acid metal salt solution And reacting to produce a hydrated silicate. Here, examples of the metal element constituting the acidic metal salt aqueous solution include alkaline earth metal elements such as magnesium, calcium, strontium, and barium, or titanium, zirconium, nickel, iron, and aluminum. Examples of the acidic metal salt aqueous solution include acidic metal sulfates, and aluminum sulfate is particularly preferable. As a result of earnest examination about this manufacturing method, it is 5 to 60% by weight of sodium silicate neutralization equivalent in place of mineral acid (sulfuric acid) instead of mineral acid (sulfuric acid) in any one or more steps when adding acid in three steps. By using a corresponding acidic metal salt aqueous solution (aluminum sulfate) and neutralizing with other mineral acids (sulfuric acid), the oil absorption level is such that it exhibits the penetration performance close to that of hydrated silicic acid. It has been found that both characteristics can be maintained, that is, the specific scattering coefficient can be increased by silicification, and the present invention has been achieved. Here, the addition of the acid is preferably performed in three steps. However, if the thorough pulverization step can be performed in the initial silicic acid analysis and output step, the addition of the acid does not need to be performed in three steps. However, if the number of stages is too large, the efficiency becomes poor, and it is necessary to select an appropriate number of times. When the yield is taken into consideration, the content of the fine amorphous metal compound is 0.5 to 8% by weight in terms of oxide (vs. SiO.2% By weight X-ray fluorescence analyzer Oxford ED2000 model). It is 5 to 60% by weight of the neutralization equivalent. The specific properties of the hydrated silicate (aluminum silicate) produced are as follows: the average particle size is 1 to 15 μm, preferably 3 to 15 μm, the oil absorption is 200 to 350 ml / 100 g as measured by the laser method, and The specific scattering coefficient is 300 to 450 m, which is blended in paper as an internal filler and shows the ability to improve paper opacity.2It is characterized by / kg.
[0011]
As the characteristic values of the hydrated silicate filler (aluminum silicate) in the present invention, values obtained by the following measuring methods are used. (1) Oil absorption; according to JIS K5101 method
(2) Particle size distribution measurement (laser method): Hydrated silicic acid sample slurry is added dropwise and mixed in pure water (added with 0.2% by weight of sodium hexametaphosphate dispersant) to obtain a uniform dispersion, and laser method particle size measurement The particle size is measured using a machine (equipment used: Mastersizer S type manufactured by Malvern). (3) Measurement of specific scattering coefficient of filler: With an orientation paper machine manufactured by Kumagai Riki Kogyo Co., Ltd., NYKP (semi-bleached KP): TMP: GP: DIP = 20: 30: 20: 30 Using a pulp slurry with a mixing ratio, the filler slurry obtained in each example as a filler, and the addition rate to pulp 2, 5, 8 wt%, basis weight 40g / m2Paper sheets were prepared, and after dehydration under the press conditions described in JIS P8209, they were dried with a cylinder dryer to prepare sheet samples with various addition rates. The reflectance of one sheet when this sheet sample is backed with a black standard plate using a green filter with a hunter reflectometer is R0Similarly, the reflectance when a standard white plate is backed (R0.89), Hunter opacity (JIS P 8138) was calculated, and the specific scattering coefficient of each sheet sample was calculated according to the Kubelka-Munk equation. On the other hand, each sheet sample was fired at 575 ° C., and the residue was calculated as the amount of ash. The amount of filler actually filled in the sample was calculated by subtracting the amount of ash in the sheet sample made in the same manner without addition of filler from the amount of ash in each sheet. From the amount of each filler and the specific scattering coefficient of each sheet, the specific scattering coefficient when the filler content was 100% by weight was calculated and used as the specific scattering coefficient of the filler.
[0012]
As described above, the hydrated silicate (aluminum silicate) according to the present invention is thoroughly pulverized during the first step of the reaction, that is, the final particle size is 1 to 15 μm, preferably 3 to 15 μm. As a result of the wet pulverization treatment, the oil absorption amount is not greatly reduced, the oil absorption amount is high, and the average particle diameter is in a range suitable as a paper filler, and the specific scattering coefficient is high. As a paper filler, it has improved opacity and is a particularly preferred filler having a high anti-through-through effect.
[0013]
The hydrated silicate filler (aluminum silicate) according to the present invention having the above particle properties is obtained by adding a mineral acid to a sodium silicate aqueous solution and producing a hydrated silicic acid by a neutralization reaction.2 After adding a mineral acid (sulfuric acid) in an amount corresponding to 30 to 50% by weight of the neutralization equivalent to 6 to 10% by weight of sodium silicate at a temperature not lower than 70 ° C. and not higher than the boiling point of the reaction system, A thorough wet pulverization treatment based on a strong shearing force, that is, a first step in which the wet pulverization treatment is performed so that the final particle size is 1 to 15 μm, preferably 3 to 15 μm, and then the temperature of the previous step In the second step, a substantial amount of mineral acid (sulfuric acid) is added at the above temperature and ripening is performed so as to precipitate almost the entire amount of silica. Further, mineral acid is added to adjust the pH of the slurry to 7 In the manufacturing method according to the process described in Japanese Patent Publication No. 2908253 comprising the third step of adjusting to the range of ˜3, preferably 5 to 3, in any one or more of the first step to the third step, Acidic metal salt aqueous solution (aluminum sulfate) Added. Here, the appropriate addition amount of the acidic metal salt aqueous solution (aluminum sulfate) to be added varies depending on each step, and the addition in the second to third steps is preferable. Further, if the neutralization amount with the aqueous acidic metal salt solution (aluminum sulfate) is more than 60% by weight, the oil absorption is greatly lowered, and the once increased specific scattering coefficient is also undesirably reduced. It is manufactured by neutralizing with a mineral acid (sulfuric acid) except for neutralization with an acidic metal salt aqueous solution (aluminum sulfate).
[0014]
The neutralization rate in each step is a range of an amount corresponding to 35 to 50% by weight of the neutralization equivalent of sodium silicate in the first step, and the second step is integrated with the amount added in the first step. Is preferably controlled to be 80 to 95% by weight, and the third step is about the remaining 5 to 20% by weight. The appropriate amount of the acid metal salt (aluminum sulfate) is 5 to 40% by weight in the first step, equivalent to sodium silicate neutralization, 5 to 45% by weight in the second step, and 5 to 20% by weight in the third step. Yes, the amount of neutralization with acidic metal salt (aluminum sulfate) is in a range not exceeding 60% by weight. As the amount of acidic metal salt added increases, the specific scattering coefficient of the filler produced tends to increase. On the other hand, the amount of oil absorption decreases, so it is necessary to optimize the amount and timing of addition. Because there is.
[0015]
The first step is a step of adjusting the concentration of sodium silicate aqueous solution and heating, and adding the first stage mineral acid to perform wet pulverization and aging. The wet pulverization is performed so that the final particle size is 1 to 15 μm, preferably 3 to 15 μm. As a result of this study, it was confirmed that when an acidic metal salt aqueous solution (aluminum sulfate) was added instead of mineral acid (sulfuric acid) in this step, the specific scattering coefficient of the filler produced increased, but the oil absorption decreased easily. It was done. For this reason, when adding acidic metal salt aqueous solution to a 1st process, it is desirable to make the addition amount into 40 weight% or less of neutralization equivalent amount. The reason for this is not clear, but as a result of observation with an electron microscope, the primary particles of the silicate containing the metal compound precipitated by the addition of the aqueous solution of the acidic metal salt in the first step increase, and the pore volume of the subsequent higher-order aggregate decreases. The decrease in the amount of oil absorption that seems to be due to this is large, and if an amount exceeding 40% by weight is added, the specific scattering coefficient of the filler that has once increased will decrease conversely. The second step is a step in which a substantial amount of mineral acid is dividedly added as the second step to precipitate almost the entire amount of silica, and the connection of the silica particles precipitated in the first step is strengthened. In the case of adding an acidic metal salt aqueous solution, it was confirmed that if the amount of the acidic metal salt aqueous solution (aluminum sulfate) added is up to 45% by weight, it is possible to silicate with little decrease in oil absorption. . The third step is a step of adding a mineral acid subsequent to the second step to adjust the pH of the slurry to 7 to 3, preferably 5 to 3. The addition of the mineral acid here is It is exclusively for adjusting the pH of the reaction system. Surprisingly, however, even when an aqueous acid metal salt solution (aluminum sulfate) is added to the third step, a significant effect of increasing the specific scattering coefficient can be obtained, and the oil absorption reduction is small.
[0016]
As the pulverizer used for the wet pulverization in the first step, ball mills such as a ball mill and a rod mill described in Japanese Patent Publication No. 2908253, medium agitating pulverizers such as a tower mill, an attritor, a sateley mill, a sand grinder, an annular mill, a colloid Examples thereof include a high-speed rotary pulverizer such as a mill, a homomixer, and an in-line mill. The silica or silicate particles precipitated in the present invention are very fine. In particular, since the silica precipitated in the first step is easily pulverized, it can be pulverized by a disperser or an emulsifier other than the pulverizer. These may be used in combination with a pulverizer.
[0017]
In addition, since the hydrated silicate (aluminum silicate) obtained in the third step may contain by-product sodium sulfate, filtration, washing and repulping are preferably performed.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The hydrated silicate filler according to the present invention has an average particle diameter of 1 to 15 μm, preferably 3 to 15 μm as measured by a laser method, an oil absorption of 200 to 350 ml / 100 g, and is blended in paper as an internal filler. The specific scattering coefficient showing the ability to improve the opacity of paper is 300-450 m2/ kg, especially when applied as a paper filler, it exhibits light weight, high opacity, high whiteness, and excellent anti-through-through effect. In addition, since thorough pulverization during the reaction reduces the number of coarse particles and reduces the average particle size, it also has the effect of reducing powder falling off when printing internally added paper.
As described above, in the hydrated silicic acid production method described in Patent Publication 2908253, a part of acidic metal salt (aluminum sulfate), instead of mineral acid (sulfuric acid), is converted into a silicate by using an appropriate amount at an appropriate addition time, Compared to conventional hydrated silicates, oil absorption and specific scattering coefficient can be balanced at a high level.
[0019]
【Example】
Examples of the present invention will be specifically described below in comparison with comparative examples. In addition, characteristic evaluation (oil absorption amount, average particle diameter, specific scattering coefficient of the filler) of the hydrated silicate filler was carried out by the method described above. Further, the effect of preventing paper breakthrough and the measurement of the filler yield were measured by the following methods.
[0020]
Measurement of the effect of preventing paper breakthrough; using an orientation paper machine manufactured by Kumagai Riki Kogyo Co., Ltd., a mixing ratio of NYKP (semi-bleached NKP): TMP: GP: DIP = 20: 30: 20: 30 as a papermaking raw material The pulp slurry obtained in each Example was used as a filler, and the addition rate was 2,5,8% by weight with respect to pulp and the basis weight was 40 g / m.2Paper sheets were prepared, dehydrated with a press, and then dried with a cylinder dryer to prepare a sheet sample. This sheet sample was subjected to the first single-sided printing with an ink volume (0.6 ml) by an RI test printing machine using a newspaper ink for tsubo [New King HL ink, Toyo Ink Co., Ltd.]. Thereafter, the second printing was performed on a sample separately prepared with the remaining ink. Similarly, printing was carried out by changing the print density by reducing the number of printings in the third and fourth times. The print sample is left in an atmosphere of 23 ° C. and 50 wt% RH for 24 hours, and then the reflectance of the printed back surface is measured with a Macbeth reflection densitometer. ) Was calculated. See-through value = (reflectance of printed back surface / reflectance of unprinted back surface) × 100 (% by weight) From the see-through value at 4 levels of print density, the print density with Macbeth reflection densitometer is 1.05 The strike-through value at the time was calculated. Therefore, the show-through value described indicates a value when printing is performed at a print density of 1.05.
[0021]
Example 1
(1) First step (neutralization rate 40%); commercially available No. 3 sodium silicate (SiO2: 20.0% by weight, Na in reaction vessel (200 liters))2(O: 9.5 wt%) is diluted with water and SiO2 As a result, 200 liters of a 6.7% by weight diluted sodium silicate solution was prepared. After heating this sodium silicate solution to 85 ° C., an amount of aluminum sulfate (Al2OThree8% by weight (hereinafter abbreviated as “band”) was added at a dropping rate of 200 g / min under sufficiently vigorous stirring so that no coarse gel was generated, and then an amount corresponding to 30% by weight of the neutralization equivalent. Sulfuric acid (concentration 98% by weight) was added in the same manner. After completion of the addition, the partially neutralized liquid obtained was aged while being stirred, and at the same time circulated with a vertical sand grinder (capacity 2 gallons, 1 mm diameter glass beads filling rate 70% by weight) (target particle size of 7 μm) Grinded. This aging and pulverization treatment was performed for 3 hours.
[0022]
(2) Second step (neutralization rate 40%); Next, the slurry temperature is raised to 90 ° C., and sulfuric acid having the same concentration as in the first step is 80% by weight of the neutralization equivalent under the same conditions as in the first step. And aged for 32 minutes under stirring. (3) Third step (neutralization rate 20%): Subsequently, sulfuric acid having the same concentration was added to the slurry after aging at the same rate at an addition rate of 76 g / min, and the slurry pH was adjusted to 6. (4) Performance evaluation: The slurry after completion of the third step was filtered, washed with water, repulped into pure water, and a hydrated silica slurry was recovered. The average particle diameter of the obtained slurry was measured, and paper was made as a filler by the method described above, and the specific scattering coefficient of the filler, the back-through prevention effect and the filler yield were evaluated. The slurry was filtered, dissolved in ethanol to a solid content of 10% by weight, filtered again, dried at 105 ° C., and the oil absorption was measured. The results are shown in Table 1 in comparison with the fluctuation conditions applied.
[0023]
Example 2
In the neutralization treatment of the first step, a band corresponding to 20% by weight of the neutralization equivalent was added at a dropping rate of 200 g / min, and the rest was hydrated under the same conditions as in Example 1 except that sulfuric acid was used. Silicate (aluminum silicate) slurry was prepared. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0024]
Example 3
In the neutralization treatment of the first step, a band corresponding to 30% by weight of the neutralization equivalent was added at a dropping rate of 200 g / min, and the rest was hydrated under the same conditions as in Example 1 except that sulfuric acid was used. Silicate (aluminum silicate) slurry was prepared. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0025]
Example 4
In the neutralization treatment of the first step, a band corresponding to 40% by weight of the neutralization equivalent was added at a dropping rate of 200 g / min, and the rest was hydrated under the same conditions as in Example 1 except that sulfuric acid was used. Silicate (aluminum silicate) slurry was prepared. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0026]
Example 5
For the neutralization treatment in the first step, 40% by weight of sulfuric acid corresponding to the neutralization amount is used, and in the neutralization treatment in the second step, an amount of band corresponding to 10% by weight of the neutralization equivalent is 200 g / min. A hydrated silicate (aluminum silicate) slurry was produced under the same conditions as in Example 1 except that sulfuric acid was used for the remainder, and the remainder was added. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0027]
Example 6
For the neutralization treatment in the first step, 40% by weight of sulfuric acid corresponding to the neutralization amount is used, and in the neutralization treatment in the second step, an amount of band corresponding to 20% by weight of the neutralization equivalent is 200 g / min. A hydrated silicate (aluminum silicate) slurry was produced under the same conditions as in Example 1 except that sulfuric acid was used for the remainder, and the remainder was added. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0028]
Example 7
For the neutralization treatment in the first step, 40% by weight of sulfuric acid corresponding to the neutralization amount is used, and in the neutralization treatment in the second step, an amount of band corresponding to all 40% by weight of the neutralization equivalent is 200 g / A hydrated silicate (aluminum silicate) slurry was produced under the same conditions as in Example 1 except that the addition was performed at a dropping rate of minutes, and the remainder was used with sulfuric acid. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0029]
Example 8
The neutralization treatment in the third step was carried out in the same manner as in Example 1 except that a band corresponding to 10% by weight of the neutralization equivalent was added at a dropping rate of 200 g / min. A hydrated silicate (aluminum silicate) slurry was produced under the same conditions. The sulfuric acid addition in the third step was 76 g / min. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0030]
Example 9
Example 1 except that sulfuric acid was added in all of the first and second steps, sulfuric acid was not used in the neutralization equivalent of 20% by weight in the third step, and all bands were used and added at a dropping rate of 200 g / min. A hydrated silicate (aluminum silicate) slurry was produced under the same conditions. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0031]
Example 10
Sulfuric acid was not used for all the neutralization equivalents of 40% by weight in the first step, and a band was added at a drop rate of 200 g / min. Further, 20% of the neutralization equivalents of 40% by weight in the second step was sulfuric acid. A hydrated silicate (aluminum silicate) slurry was produced under the same conditions as in Example 1 except that the band was added at 200 g / min for neutralization, and the remaining 20 wt% was similarly neutralized with sulfuric acid. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 1.
[0032]
Comparative Example 1
In all of the first, second and third steps, a hydrated silicic acid slurry was produced under the same conditions as in Example 1 except that no band was used and sulfuric acid was used in all of the 100% by weight equivalent to neutralization. The physical properties of the obtained slurry were measured and evaluated in the same manner as in Example 1, and the results are listed in Table 2.
[0033]
Comparative Example 2
A hydrated silicate (aluminum silicate) slurry was produced under the same conditions as in Example 1 except that sulfuric acid was not used in all of the first, second and third steps, and a band corresponding to 100% by weight of neutralization was used. did. The obtained slurry was measured and evaluated in the same manner as in Example 1, and the results are listed in Table 2.
[0034]
Comparative Example 3
Rhodia Japan Tixolex 17 (aluminum silicate salt), which is a commercially available hydrated silicate, was dispersed in water to prepare a 10 wt% slurry, and physical properties were measured and evaluated in the same manner as in Example 1 for the resulting slurry. The results are shown in Table 2.
[0035]
Comparative Example 4
US J. which is a commercially available hydrated silicate. M Huber HYDREX-P (magnesium silicate) was dispersed in water to prepare a 10 wt% slurry, and the physical properties of the resulting slurry were measured and evaluated in the same manner as in Example 1. The results are also shown in Table 2. did.
[0036]
[Table 1]
[Table 2]
From the results in Table 1, since the hydrated silicate (aluminum silicate) according to the present invention has a high level of specific scattering coefficient and oil absorption in a well-balanced manner, the opacity and whiteness of the paper are high, and the anti-through-through effect is also achieved. I understand that it is expensive. In Comparative Examples 3 and 4, which are commercially available hydrated silicates, the oil absorption is low, and the effect of preventing back-through is low. The reason why the decrease in oil absorption can be reduced even when silicified is not clear, but it seems that the thorough grinding effect in the first step has an influence.
Further, as can be seen from Comparative Example 2, when the amount of neutralization with aluminum sulfate increases, the specific scattering coefficient increased by silicification decreases, and the oil absorption decreases greatly, so the amount of aluminum sulfate added is It is necessary to be 60% by weight or less, that is, the metal element content (oxide conversion vs. SiO 2)2Weight percent) must be kept adequate.
[0039]
【The invention's effect】
As described above, the hydrated silicate (aluminum silicate) according to the present invention has a high level of specific scattering coefficient and oil absorption in a well-balanced manner. I understand that there is. Moreover, according to the manufacturing method which concerns on this invention, it will become possible to industrially produce the said high performance hydrated silicic acid for paper fillers efficiently. Therefore, it contributes greatly to the paper industry. The hydrated silicic acid of the present invention is useful not only for paper fillers but also as filler for coated papers because of its high specific scattering coefficient.
Claims (5)
Priority Applications (1)
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| JP2001082820A JP3728215B2 (en) | 2001-03-22 | 2001-03-22 | Aluminum silicate |
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| JP2001082820A JP3728215B2 (en) | 2001-03-22 | 2001-03-22 | Aluminum silicate |
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| US7465694B2 (en) * | 2004-09-30 | 2008-12-16 | Nippon Paper Industries Co., Ltd. | Thermally sensitive recording medium |
| JP4742963B2 (en) * | 2006-04-17 | 2011-08-10 | 王子製紙株式会社 | Porous filler and production method thereof, porous filler slurry and paper |
| JP4840002B2 (en) * | 2006-06-23 | 2011-12-21 | 王子製紙株式会社 | Coated paper for printing and method for producing the same |
| JP5309524B2 (en) * | 2007-10-15 | 2013-10-09 | 王子ホールディングス株式会社 | Inkjet recording paper |
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