JP4452861B2

JP4452861B2 - Method for producing foamable porous member and foamable porous member

Info

Publication number: JP4452861B2
Application number: JP2003181681A
Authority: JP
Inventors: 朝生佐藤; 公康加藤
Original assignee: 稲垣鉱業株式会社
Priority date: 2003-06-25
Filing date: 2003-06-25
Publication date: 2010-04-21
Anticipated expiration: 2023-06-25
Also published as: JP2005015269A

Description

【０００１】
【発明の属する技術分野】
本発明は発泡性多孔質部材に関する。より詳しくは、発泡成分の発泡による体積増加を抑制することのできる発泡性多孔質部材の製造方法と発泡性多孔質部材とに関する。
【０００２】
【従来の技術】
発泡性多孔質部材は、原料中に発泡性の成分を含んでいる。そして、その発泡成分がある焼成温度で発泡して体積が増加することにより、焼成後の嵩比重を小さくして軽量化した部材である。特にセラミックスの分野においては広く知られている（例えば、特許文献１など）。当該文献では、原料中に焼成を経たセラミックス質廃材と、粘土質及び／又は長石質を含み、焼成により発泡して、焼成後の嵩比重が０．３〜２．０の範囲である軽量発泡セラミックスについて開示されている。
【０００３】
【特許文献１】
特開２０００−２９００８３号公報
【０００４】
【発明が解決しようとする課題】
しかし、このようにして形成される発泡性セラミックスは、焼成温度や、焼成雰囲気などの僅かな変化によって発泡成分の発泡の程度が大きく変化するために、焼成後の焼成体の形状が不安定となる。このため、タイルなどのように、寸法や形状に要求される精度が厳しい窯業製品へはあまり適用されていなかった。
【０００５】
本発明は、上記の事情に鑑みてなされたもので、発泡成分の発泡条件に左右されることなく焼成体の体積膨張を抑制することができる発泡性多孔質部材の製造方法と発泡性多孔質部材とを提供することを目的とする。
【０００６】
【課題を解決するための手段】
本発明の発泡性多孔質部材の製造方法は、成形原料粉末に加熱によって発泡する発泡成分を配合した発泡性成形原料粉末に、加熱によって消失する消失材を造粒してなる含水率が４０〜５０重量％の消失造粒粉末を、該発泡性成形原料粉末を１００重量％として１０〜５０重量％配合して発泡性多孔質成形原料となし、該発泡性多孔質成形原料を、所定形状の成形体に成形し、該成形体を焼成することにより、前記消失造粒粉末が消失して形成される互いに独立した気孔が、発泡による前記発泡成分の体積増加分を吸収して、前記成形体の焼成前後の体積変化を抑制するようにしたことを特徴とする。すなわち、本発明の発泡性多孔質部材の製造方法によれば、加熱により消失材が消失して形成された気孔が、発泡成分が発泡することにより増加した体積増加分を吸収することにより、焼成前後の成形体の体積変化を抑制することができる。
【０００７】
本発明の発泡性多孔質部材の製造方法において、消失材は有機物であるのが好ましく、さらに、前記有機物は、紙であることが好ましい。紙を用いると、加熱よって消失する際に、有毒ガスや可燃ガスなどを放出することがないので、無毒、無害である。
【０００８】
また、前記消失造粒粉末は、該消失造粒粉末の中心部を通る厚さにおいて、最も薄い部分を１としたときに最も厚い部分が３以下の粒状であるのが好ましい。消失造粒粉末の厚さがこの範囲にないと、消失造粒粉末同士が集積しやすく、成形原料粉末中に消失造粒粉末を混合する際、均一に分散させることが難しい。
【０００９】
また、消失造粒粉末は、水などの極性溶媒を適度に含むことにより、成形原料粉末中に均一に分散させやすくなる。そして、消失材をさらに造粒したことにより、乾式プレス成形法で成形した場合に発生するラミネーションを防止できる。
【００１０】
本発明の発泡性多孔質部材の製造方法において、前記成形原料粉末は、セラミックス原料粉末、金属粉末の少なくとも１種であることが望ましい。また、前記セラミックス原料粉末は、粘土、陶石、蝋石、珪石、石灰、長石、滑石、窒化珪素および炭化珪素の少なくとも１種であることが望ましい。
また、本発明の発泡性多孔質部材は、成形原料粉末に加熱によって発泡する発泡成分を配合した発泡性成形原料粉末に、加熱によって消失する消失材を造粒してなる含水率が４０〜５０重量％の消失造粒粉末を、該発泡性成形原料粉末を１００重量％として１０〜５０重量％配合して発泡性多孔質成形原料となし、該発泡性多孔質成形原料を、所定形状の成形体に成形し、該成形体を焼成してなるところの、互いに独立した気孔を有し、かつ該成形体の金型寸法に対する焼成後の該成形体の寸法変化率が、−１．２０％〜−８．４８％であることを特徴とする。
【００１１】
【発明の実施の形態】
本発明の発泡性多孔質部材の製造方法は、成形原料粉末に加熱によって発泡する発泡成分を配合した発泡性成形原料粉末に、加熱によって消失する消失材を造粒してなる含水率が４０〜５０重量％の消失造粒粉末を、該発泡性成形原料粉末を１００重量％として１０〜５０重量％配合して発泡性多孔質成形原料となし、該発泡性多孔質成形原料を、所定形状の成形体に成形し、該成形体を焼成することにより、前記消失造粒粉末が消失して形成される互いに独立した気孔が、発泡による前記発泡成分の体積増加分を吸収して、前記成形体の焼成前後の体積変化を抑制するようにしたことを特徴とする。すなわち、本発明の発泡性多孔質部材の製造方法は、加熱により消失材が消失して形成された気孔が、発泡成分が発泡することにより増加した体積増加分を吸収することにより、焼成前後の成形体の体積変化を抑制しようとするものである。
【００１２】
本発明の製造方法による焼成前後の発泡性多孔質部材の体積変化を抑制する作用は明らかではないが、概ね以下の通りであると推察される。図１および図２によって説明する。
【００１３】
消失造粒粉末は、発泡成分が発泡するよりも低温で消失するので、焼成途中の焼成体の内部は、図１に模式的に示すように発泡成分１を含む成形原料２の中に消失造粒粉末が消失して形成された気孔３が多数分散した状態となっている。
【００１４】
この状態でさらに焼成を続けて成形体の温度が発泡成分の発泡温度に到達すると、図２に示すように発泡成分１の体積ａ１（●で表す）は膨張して体積ａ２（矢印方向に膨張した点線の円で示す）となる。すなわち、発泡前の全発泡成分の体積をＡ１として、発泡後の全発泡成分の体積をＡ２とすると、Ａ＝Ａ２−Ａ１が全発泡成分の体積増加量である。
【００１５】
一方、消失造粒粉末が消失して形成された気孔３の体積ｂ１（○で表す）は発泡成分の発泡によって増加した体積増加分を吸収して体積ｂ２（矢印方向に縮小した点線の円で示す）となる。
【００１６】
すなわち、発泡前の全気孔の体積をＢとして、Ａ＜Ｂの場合（発泡成分の体積増加量が、発泡前の気孔の全体積よりも小さい）には、発泡成分による焼成体の体積増加は発生しない。つまり、発泡成分の体積増加量以上の体積の気孔を形成するようにすれば、焼成後の焼成体の体積増加は成形原料の体積増加量だけとなる。この結果、焼成体（発泡性多孔質部材）の嵩比重は、気孔量の増加に伴って小さくなる。
【００１７】
発泡性成分としては加熱によって発泡する発泡性を有するものであれば特に限定されるものではない。火山灰などに含まれる真珠岩や黒曜石などの天然ガラス成分、あるいはフライアッシュや廃ガラス等の人工ガラス成分などを例示することができる。
【００１８】
発泡成分は、発泡成分を含む発泡材を単独で配合してもよいが、発泡成分を含む発泡材と成形原料粉末とを、ある温度で発泡するように予め調整した発泡性成形原料粉末を用いることが好ましい。これは部材の焼成温度に合わせて耐火度を調整して、発泡現象をある程度調節することができるからである。
【００１９】
消失造粒粉末は、主として加熱によって消失する消失材を造粒して得られる。消失材は、加熱によって消失するものであり、消失材としては、有機物が好ましく、より好ましくは、でんぷん等の多糖類、有機質繊維、セルロース、紙、おが屑などである。特に、古新聞、古雑誌などの古紙を用いると、資源の有効利用、再利用が可能となる。上記の消失材であれば、加熱によって消失する際に、有毒ガス、可燃性ガスを放出することがなく、無毒、無害である。
【００２０】
消失材は、造粒する前に粉砕し粉砕物とするのが好ましい。消失材が糸状の繊維質であれば、繊維質を細かく切断し粉砕するのが良い。消失材が粉砕されず糸状であると、消失材が絡み合うため、望ましい造粒をすることができない。粉砕は、糸状のものがなくなる程度まで行うのが好ましい。造粒に用いられる粉砕物は、造粒する消失造粒粉末の粒子径に応じて、その大きさを決定する必要がある。消失造粒粉末の粒子径が小さくなる程、消失材の粉砕物の大きさが小さくなるように粉砕する必要がある。消失材を粉砕する際には、通常の粉砕機やカッターを用いることができ、所望の大きさに粉砕できるものであれば、特に限定するものではない。
【００２１】
消失造粒粉末の造粒は、従来の造粒方法で行うことができる。具体的には、転動型、振動型、圧縮成形型、噴射型等の各造粒形式の造粒方法が好ましい。造粒により得られた消失造粒粉末は、粒状であるのが好ましい。消失造粒粉末は、その中心部を通る厚さにおいて、最も薄い部分の厚さを１としたときに最も厚い部分の厚さが３以下が好ましく、球形に近いほど、より好ましい。この比が１：１〜１：３にないと、消失造粒粉末同士が集積し易くなり、消失造粒粉末を成形原料粉末中に均一に分散させることが困難となり、発泡成分の膨張による体積増加量を吸収する独立した多数の気孔を得られなくなる。
【００２２】
また、消失造粒粉末の粒径には、特に限定はなく、発泡成分の含有量や目的とする気孔の大きさに応じて適宜決定すればよい。
なお、消失造粒粉末の粒径は、消失造粒粉末の粒子径に加え、造粒条件、具体的には、添加物の量、造粒に使用するミキサーの種類や回転速度等によっても決定される。造粒条件を適宜選択することにより、所望のサイズの消失造粒粉末が得られる。
【００２３】
さらに、消失造粒粉末は、極性溶媒をバインダーとして含んでも良い。粉砕した消失材に添加するバインダーの添加量が多いと、消失造粒粉末の粒子径は大きくなる。極性溶媒は、水が好ましく、アルコール、アセトン等の有機溶媒でも良い。また、水などにでんぷん、ＣＭＣ等を溶解した水溶液を用いても良い。消失造粒粉末にバインダーを含ませることにより、消失造粒粉末の嵩密度が増し、その結果、成形原料粉末中に消失造粒粉末を分散させる際、均一に分散させることが可能となる。また、適度に極性溶媒を含んだ消失造粒粉末は、乾式プレス成形法でセラミックス等の多孔質部材を成形した場合に発生するラミネーションを防止できる。消失造粒粉末の含水率は、造粒直後は造粒の際に使用した極性溶媒の割合にほぼ等しくなるが、乾燥後の含水率は１０〜７０ｗｔ％が好ましく、より好ましくは、４０〜５０ｗｔ％である。
【００２４】
また、消失造粒粉末の嵩比重は、０．１ｇ／ｃｍ³以上が好ましく、より好ましくは、０．２５ｇ／ｃｍ³以上である。嵩比重が０．２５ｇ／ｃｍ³未満であると、焼成途中の成形体にラミネーションなどの不具合を生じることがある。
【００２５】
成形原料粉末は、セラミックス原料粉末、金属粉末、の少なくとも１種であることが望ましい。通常の粉末冶金・粉末成形に用いられる成形原料粉末であれば、特に限定はない。
【００２６】
セラミックス原料粉末は、粘土、陶石、蝋石、珪石、石灰、滑石、長石、珪砂等、および、窒化珪素、炭化珪素等の少なくとも１種であるのが望ましい。上記以外にも、シャモット、釉原料、顔料などを必要に応じて添加しても良い。これらの成形原料粉末の配合率は、製造するセラミックスの種類、成形方法、焼成温度等に依存するものである。成形原料粉末の粒径に特に限定はなく、一次粒子をさらに造粒した二次粒子を用いても良い。
【００２７】
また、成形原料粉末に発泡成分を配合した発泡性成形原料粉末に対する消失造粒粉末の好ましい配合率は、使用する成形原料粉末の種類やサイズ、発泡成分の種類や配合量、さらに、発泡性多孔質部材の形状や用途にも依るが、５０ｗｔ％以下が好ましく、より好ましくは３０ｗｔ％以下である。配合率がこの範囲であれば、不具合なく成形し、かつ、焼成体の体積膨張を抑制することができる。
【００２８】
発泡性成形原料粉末に消失造粒粉末を混合する際には、通常使用されるコンクリートミキサー、高速流動式ミキサー（フルダイズドミキサー）等のミキサーを用いるのが望ましい。混合条件としては、消失造粒粉末の粒状の形状が大きく崩れない程度である必要がある。消失材を造粒した消失造粒粉末の表面積は、造粒前の消失材の表面積よりも小さくなるため、消失造粒粉末同士が集積し難い。また、成形原料粉末との親和性も良好となるため、混合により消失造粒粉末が発泡性成形原料粉末中に均一に分散した発泡性多孔質原料を得ることができる。
【００２９】
上記のように混合された発泡性多孔質成形原料を成形し焼成することにより、粒状で、隣接する他の気孔とは連続しない気孔をもつ発泡性多孔質部材が得られる。
【００３０】
発泡性多孔質成形体は、乾式製法で成形可能である。したがって、金型プレス成形法、ラバープレス法、押出成形法など、選択した発泡性成形原料粉末に適した方法であれば、いずれの製造法も適用できる。
【００３１】
また、発泡性多孔質成形体の焼成についても特に限定することはなく、通常の方法で焼成することができる。例えば、乾燥した成形体をトンネルキルンで最高温度が１１００〜１３００℃となるように酸化焼成すればよい。
【００３２】
このようにして形成される気孔は、粒状で、さらに、隣接する他の気孔とは連続しないことが好ましい。気孔が均一に分散し単独で存在すると、気孔が連続して存在するものに比べ、成形原料粉末が連続して存在する部分が多い。成形原料粉末は焼成後の多孔質部材中で柱（または壁）の役割を果たすので、互いに連続しない粒状の気孔をもつ多孔質部材は、成形原料粉末がもつ収縮率や強度といった特性を維持することができる。
【００３３】
本発明による発泡性多孔質部材では、発泡成分の発泡による体積増加量を形成された気孔によって吸収するので、焼成後の収縮率は、発泡成分を配合しない多孔質部材とほぼ同程度であり、大差はない。その結果、本発明になる発泡性多孔質部材を生産するに当たっては、既存の生産設備、例えば、金型、口金等が使用できるという利点がある。
【００３４】
また、互いに連続しない粒状の気孔を適度に持つ発泡性多孔質部材は、発泡により増加した体積は気孔によって吸収されているので、発泡しない場合に比べてその強度が僅かに劣るのみで、実用に十分耐えうる強度を有する。従って、発泡性多孔質部材でありながら高い強度を持つ部材を得ることができる。
【００３５】
【試験例】
本発明の発泡多孔質部材の製造方法を以下の試験例によってさらに具体的に説明する。
（試験例１）
回転歯式粉砕機を用いて、古新聞紙を粉砕した。その後、ＪＩＳ標準ふるいにより０．５ｍｍ以下の大きさをもつ粉砕物を得た。この粉砕物に水を添加し、高速流動式ミキサー（三井鉱山（株）製ヘンシェルミキサー）を用いて造粒し、造粒時６５％、自然乾燥後４６％の含水率の消失造粒粉末（以下、気孔材と称する）を得た。得られた気孔材の粒度分布を表１に示す。
【００３６】
【表１】

【００３７】
成形原料粉末に発泡性成分を配合した発泡性成形原料粉末として、発泡性セラミックス原料Ａ（丸美陶料（株）製ＫＥＩ−０６）、および、発泡性セラミックス原料Ｂ（丸美陶料（株）製Ｃ−１４５１）に、上記で得られた気孔材である消失造粒粉末を配合してミキサーで均一に混合分散させ、発泡性多孔質成形原料を得た。なお、気孔材の配合割合は、発泡性セラミックス原料Ａでは、０，１０，２５，３０，３５重量％の５水準とし、発泡性セラミックス原料Ｂでは、０，１０，２５，３０重量％の４水準とした。また、ミキサーは、（株）カワタスーパミキサー（ＳＭＶ−２０）を用いて、回転数：５００ｒｐｍで３０秒間の混合分散を施した。
【００３８】
得られた各発泡性多孔質成形原料を油圧プレスを用いて一定圧力で７５ｍｍ×７５ｍｍ（金型寸法８２．５ｍｍ×８２．５ｍｍ）に成形し各水準につき４枚の成形体を得た。得られた成形体を１１０℃で３時間乾燥後、トンネルキルンにて最高温度を１２３０℃として酸化焼成を施し、焼成体（発泡性多孔質部材）となし、寸法および重量を測定して嵩比重と寸法変化率を求めた。結果を表２（発泡性セラミックス原料Ａ）および表３（発泡性セラミックス原料Ｂ）に示す。なお、寸法変化率は金型寸法に対する焼成体の寸法変化率であり、プラスは金型寸法に対する増加率を、マイナスは減少率を示す。
【００３９】
【表２】

【００４０】
【表３】

【００４１】
表２および表３から、気孔材の配合割合の増加とともに、得られた焼成体の寸法は直線的に小さくなるが、嵩比重はわずかに変化しているにすぎないことが分かる。これは、焼成によって気孔材が消失することで形成された気孔が、発泡成分の発泡による体積増加を吸収し、発泡性セラミックス原料中の発泡成分以外の成分（セラミックス原料）の収縮を促進しているためと推測される。
【００４２】
気孔材を配合することによって発泡性セラミックスの発泡による体積増加が抑制され、従来（気孔材配合割合：０％の場合）と同様の成形方法で、形状の良好な発泡性セラミックスを得ることができた。
（試験例２）
気孔材を発泡性セラミックス原料Ｃ（（株）ヤマセ社製Ｇ−５１０Ｆ）に試験例１と同様の気孔材を３０重量％配合し、試験例１と同様の方法で均一に混合分散して、発泡性多孔質成形原料を得た。なお、気孔材を配合しない（配合割合：０％）の発泡性セラミックス原料Ｃを比較材とした。
【００４３】
得られた発泡性多孔質成形原料と比較材とを油圧プレスを用い一定圧力で４５ｍｍ×９５ｍｍ（金型寸法５０ｍｍ×１０５．５ｍｍ）に成形し、各々４枚ずつの成形体を得た。これらの成形体を１１０℃で３時間乾燥後、トンネルキルンにて最高温度を１２４０℃として酸化焼成を施して焼成体（発泡性多孔質部材）となし、試験例１と同様に、寸法および重量を測定して嵩比重と寸法変化率とを求めた。結果を表４に示す。
【００４４】
【表４】

【００４５】
表４より気孔材を配合することによって、焼成体（発泡性多孔質部材）の嵩比重は低下し、さらに寸法変化率は−６％前後と焼成体の体積膨張が大きく抑制されていることが分かる。
（試験例３）
試験例１と同様の発泡性セラミックス原料Ａおよび発泡性セラミックス原料Ｂに、各々３０重量％の気孔材を配合して試験例１と同様の方法で均一に混合分散し、発泡性多孔質成形原料となした。
【００４６】
この発泡性多孔質成形原料を油圧プレスを用いて一定圧力で５０ｍｍ×５０ｍｍ（金型寸法５０ｍｍ×５０ｍｍ）に成形し、各原料について１２枚ずつの成形体を得た。得られた成形体を１１０℃で３時間乾燥後、電気炉（共栄電気炉製作所製）中で最高温度が１１８５℃、１２２０℃、１２４０℃の３水準となるように酸化焼成して、各最高温度で原料毎に各々４枚ずつの焼成体（発泡性多孔質部材）を得た。これらの焼成体の寸法および重量を測定して嵩比重と寸法変化率とを求めた。結果を表５（発泡性セラミックス原料Ａ）および表６（発泡性セラミックス原料Ｂ）に示す。
【００４７】
【表５】

【００４８】
【表６】

【００４９】
一般的に、発泡性セラミックス原料からなる成形体を焼成する場合には、焼成温度が異なると、発泡性セラミックス原料中の発泡成分の発泡程度が異なるために、焼成体の寸法変化率はプラス側（体積増加）で大きく異なる。しかし、本試験例では、焼成温度が異なっても焼成によって形成された気孔が、発泡成分の体積増加分を吸収したために、焼成体の寸法変化率は焼成温度に係わらずマイナス（体積減少）となった。すなわち、焼成温度の変動による焼成体の寸法変化率の変動は極めて小さいことが分かる。
【００５０】
【発明の効果】
本発明の発泡性多孔質部材の製造方法によれば、焼成の温度条件に影響されることが小さく性状の安定した発泡性多孔質部材を得ることができる。従って、焼成後の寸法などの製品品質について精度の高い設計が可能となり、狙い通りの品質を得ることができる。このため、発泡性多孔質部材の品質を向上するとともに生産性をも高めることができる。
【００５１】
従来の発泡性多孔質部材では、発泡成分の不安定な体積膨張により形状安定性に問題があった。しかし、本発明においては、寸法が収縮する発泡性多孔質部材を得ることができるので、製品の形状安定性が大きく向上する。
【００５２】
また、消失造粒粉末の配合割合を変化させることで、発泡性多孔質部材の収縮率を調整することができる。従って、従来製品と寸法変化率の等しい発泡性多孔質部材を得ることができ、既存の設備や釉薬などをそのまま適用することができて効率的である。
【００５３】
本発明の発泡性多孔質部材の製造方法は、大型の複合タイル、あるいは、断熱レンガや軽量ブロックなど断熱性や軽量性に優れた建築材料等の製造に特に好適に適用することができ、品質の安定化や生産性の向上に多大な効果を奏する。
【図面の簡単な説明】
【図１】加熱により消失造粒粉末が消失して気孔が形成された様子を示す模式図である。
【図２】発泡成分が発泡して体積増加しても、気孔が縮小することでこの増加体積を吸収する様子を説明する説明図である。
【符号の説明】
１：発泡成分２：成形原料３：気孔[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the expandable porous member. More specifically, the present invention relates to a method for producing a foamable porous member capable of suppressing an increase in volume due to foaming of a foaming component and a foamable porous member .
[0002]
[Prior art]
The foamable porous member contains a foamable component in the raw material. And it is the member which reduced the bulk specific gravity after baking and reduced in weight by foaming at the certain firing temperature and the volume increasing. In particular, it is widely known in the field of ceramics (for example, Patent Document 1). In the said literature, the lightweight foaming which contains the ceramic waste material which passed through baking in a raw material, and clay and / or feldspar, foams by baking, and the bulk specific gravity after baking is the range of 0.3-2.0. Ceramics are disclosed.
[0003]
[Patent Document 1]
JP 2000-290083 A [0004]
[Problems to be solved by the invention]
However, the foamable ceramics formed in this way have an unstable shape after firing because the degree of foaming of the foaming component changes greatly due to slight changes in firing temperature, firing atmosphere, etc. Become. For this reason, it has not been applied so much to ceramic products such as tiles, where the precision required for dimensions and shapes is severe.
[0005]
The present invention has been made in view of the above circumstances, the method of manufacturing a sparkling porous member capable of suppressing the volume expansion of the sintered body without being affected by the foaming conditions of the foam components and the foaming porous It is an object to provide a member .
[0006]
[Means for Solving the Problems]
In the method for producing a foamable porous member of the present invention, the moisture content formed by granulating a foaming molding raw material powder in which a foaming component that foams by heating in the molding raw material powder is blended is disappeared by heating. 50% by weight of the disappeared granulated powder is mixed with 10 to 50% by weight of the foamable molding raw material powder as 100% by weight to form a foamable porous molding raw material. By forming the molded body and firing the molded body, the mutually independent pores formed by the disappearance of the lost granulated powder absorb the volume increase of the foamed component due to foaming, and the molded body It is characterized in that the volume change before and after firing is suppressed. That is, according to the method for producing a foamable porous member of the present invention, the pores formed by the disappearance of the disappearing material by heating absorb the volume increase increased by foaming of the foaming component, thereby firing. Volume change of the front and rear molded bodies can be suppressed.
[0007]
In the method for producing a foamable porous member of the present invention, the disappearing material is preferably an organic material, and the organic material is preferably paper. When paper is used, it is non-toxic and harmless because it does not release toxic gas or combustible gas when it disappears by heating.
[0008]
In addition, the vanishing granulated powder is preferably granular in which the thickest portion is 3 or less when the thinnest portion is 1 in the thickness passing through the central portion of the vanishing granulated powder. If the thickness of the lost granulated powder is not within this range, the lost granulated powder is likely to accumulate, and it is difficult to uniformly disperse the lost granulated powder in the forming raw material powder.
[0009]
Further, the disappearing granulated powder can easily be uniformly dispersed in the forming raw material powder by appropriately containing a polar solvent such as water. Further, by further granulating the disappearing material, it is possible to prevent the lamination that occurs when it is molded by the dry press molding method.
[0010]
In the method for producing a foamable porous member of the present invention, the forming raw material powder is preferably at least one of ceramic raw material powder and metal powder. The ceramic raw material powder is preferably at least one of clay, porcelain stone, wax stone, silica stone, lime, feldspar, talc, silicon nitride, and silicon carbide.
In addition, the foamable porous member of the present invention has a moisture content of 40 to 50 obtained by granulating a foaming molding raw material powder in which a foaming component that foams by heating is blended with a molding raw material powder and disappearing material that disappears by heating. 10% to 50% by weight of the disappearing granulated powder is mixed with 10% by weight of the foamable molding raw material powder to form a foamable porous molding raw material. The foamable porous molding raw material is molded into a predetermined shape. The molded body has pores independent of each other , and the dimensional change rate of the molded body after firing with respect to the mold size of the molded body is −1.20%. It is characterized by -8.48%.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing a foamable porous member of the present invention, the moisture content formed by granulating a foaming molding raw material powder in which a foaming component that foams by heating in the molding raw material powder is blended is disappeared by heating. 50% by weight of the disappeared granulated powder is mixed with 10 to 50% by weight of the foamable molding raw material powder as 100% by weight to form a foamable porous molding raw material. By forming the molded body and firing the molded body, the mutually independent pores formed by the disappearance of the lost granulated powder absorb the volume increase of the foamed component due to foaming, and the molded body It is characterized in that the volume change before and after firing is suppressed. That is, in the method for producing a foamable porous member of the present invention, the pores formed by the disappearance of the disappearing material by heating absorb the volume increase increased by foaming of the foaming component, so that before and after firing. It is intended to suppress the volume change of the molded body.
[0012]
Although the effect of suppressing the volume change of the foamable porous member before and after firing by the production method of the present invention is not clear, it is presumed that it is generally as follows. This will be described with reference to FIGS.
[0013]
Since the disappeared granulated powder disappears at a lower temperature than the foamed component foams, the interior of the fired body during firing is disappeared into the forming raw material 2 containing the foamed component 1 as schematically shown in FIG. A large number of pores 3 formed by the disappearance of the granular powder are dispersed.
[0014]
When firing is continued in this state and the temperature of the molded body reaches the foaming temperature of the foaming component, the volume a1 (indicated by ●) of the foaming component 1 expands and the volume a2 (expands in the direction of the arrow) as shown in FIG. Indicated by a dotted circle). That is, assuming that the volume of all foamed components before foaming is A1, and the volume of all foamed components after foaming is A2, A = A2-A1 is the volume increase amount of all foamed components.
[0015]
On the other hand, the volume b1 (represented by ◯) of the pores 3 formed by disappearance of the disappeared granulated powder absorbs the volume increase increased by the foaming of the foaming component, and is the volume b2 (dotted circle reduced in the arrow direction). Show).
[0016]
That is, when the volume of all pores before foaming is B, and A <B (the volume increase amount of the foaming component is smaller than the total volume of pores before foaming), the volume increase of the fired body by the foaming component is Does not occur. That is, if pores having a volume equal to or larger than the volume increase amount of the foaming component are formed, the volume increase of the fired body after firing is only the volume increase amount of the forming raw material. As a result, the bulk specific gravity of the fired body (foamable porous member) decreases as the amount of pores increases.
[0017]
The foamable component is not particularly limited as long as it has foamability that foams by heating. Examples thereof include natural glass components such as pearlite and obsidian contained in volcanic ash, or artificial glass components such as fly ash and waste glass.
[0018]
As the foaming component, a foaming material containing a foaming component may be blended alone, but a foamable molding raw material powder prepared in advance so as to foam the foaming material containing the foaming component and the molding raw material powder at a certain temperature is used. It is preferable. This is because the foaming phenomenon can be adjusted to some extent by adjusting the fire resistance according to the firing temperature of the member.
[0019]
The disappearing granulated powder is obtained by granulating a disappearing material that disappears mainly by heating. The disappearing material disappears by heating, and the disappearing material is preferably an organic material, more preferably polysaccharides such as starch, organic fibers, cellulose, paper, sawdust, and the like. In particular, when old paper such as old newspapers and old magazines is used, resources can be effectively used and reused. If it is said vanishing material, when it lose | disappears by heating, it does not discharge | release toxic gas and combustible gas, and it is nontoxic and harmless.
[0020]
The vanishing material is preferably pulverized before granulation to obtain a pulverized product. If the disappearing material is a fibrous fiber, it is preferable to cut and pulverize the fiber finely. If the disappearing material is not pulverized and is in the form of a thread, the disappearing material is intertwined, so that desirable granulation cannot be performed. The pulverization is preferably performed to such an extent that the filamentous material is eliminated. It is necessary to determine the size of the pulverized product used for granulation according to the particle diameter of the disappeared granulated powder to be granulated. It is necessary to grind so that the size of the pulverized material of the disappearing material becomes smaller as the particle diameter of the disappeared granulated powder becomes smaller. When the lost material is pulverized, a normal pulverizer or cutter can be used, and there is no particular limitation as long as it can be pulverized to a desired size.
[0021]
The disappearing granulated powder can be granulated by a conventional granulation method. Specifically, granulation methods of each granulation type such as a rolling type, a vibration type, a compression molding type, and an injection type are preferable. The disappearing granulated powder obtained by granulation is preferably granular. The disappeared granulated powder has a thickness passing through the center of the thinnest portion, where the thickness of the thinnest portion is 1, the thickness of the thickest portion is preferably 3 or less, and the closer to a sphere, the more preferable. If this ratio is not 1: 1 to 1: 3, the lost granulated powder is likely to be accumulated, and it is difficult to uniformly disperse the lost granulated powder in the forming raw material powder. A large number of independent pores that absorb the increased amount cannot be obtained.
[0022]
The particle size of the disappeared granulated powder is not particularly limited, and may be appropriately determined according to the content of the foaming component and the target pore size.
The particle size of the lost granulated powder is determined not only by the particle size of the lost granulated powder, but also by the granulation conditions, specifically the amount of additives, the type of mixer used for granulation, the rotational speed, etc. Is done. By appropriately selecting the granulation conditions, a disappeared granulated powder having a desired size can be obtained.
[0023]
Further, the disappearing granulated powder may contain a polar solvent as a binder. When the amount of the binder added to the pulverized disappearing material is large, the particle diameter of the disappearing granulated powder becomes large. The polar solvent is preferably water, and may be an organic solvent such as alcohol or acetone. Further, an aqueous solution in which starch, CMC or the like is dissolved in water or the like may be used. By including the binder in the lost granulated powder, the bulk density of the lost granulated powder is increased. As a result, when the lost granulated powder is dispersed in the forming raw material powder, it can be uniformly dispersed. Moreover, the disappearing granulated powder containing a moderately polar solvent can prevent lamination that occurs when a porous member such as ceramics is molded by a dry press molding method. The moisture content of the lost granulated powder is almost equal to the proportion of the polar solvent used during granulation immediately after granulation, but the moisture content after drying is preferably 10 to 70 wt%, more preferably 40 to 50 wt%. %.
[0024]
Further, the bulk specific gravity of the disappeared granulated powder is preferably 0.1 g / cm ³ or more, more preferably 0.25 g / cm ³ or more. If the bulk specific gravity is less than 0.25 g / cm ³ , defects such as lamination may occur in the molded product during firing.
[0025]
The forming raw material powder is preferably at least one of ceramic raw material powder and metal powder. There is no particular limitation as long as it is a forming raw material powder used for ordinary powder metallurgy and powder molding.
[0026]
The ceramic raw material powder is desirably at least one of clay, porcelain stone, wax stone, silica stone, lime, talc, feldspar, silica sand, etc., and silicon nitride, silicon carbide and the like. In addition to the above, chamotte, koji raw materials, pigments and the like may be added as necessary. The blending ratio of these forming raw material powders depends on the type of ceramic to be manufactured, the forming method, the firing temperature, and the like. The particle size of the forming raw material powder is not particularly limited, and secondary particles obtained by further granulating primary particles may be used.
[0027]
In addition, the preferred blending ratio of the disappeared granulated powder with respect to the foamable molding raw material powder in which the foaming component is blended with the molding raw material powder is the type and size of the molding raw material powder used, the type and blending amount of the foaming component, and further Although it depends on the shape and use of the mass member, it is preferably 50 wt% or less, more preferably 30 wt% or less. When the blending ratio is within this range, molding can be performed without any problem, and volume expansion of the fired body can be suppressed.
[0028]
When mixing the disappeared granulated powder into the foamable forming raw material powder, it is desirable to use a mixer such as a commonly used concrete mixer or a high-speed fluidized mixer (full-solidified mixer). As a mixing condition, it is necessary that the granular shape of the disappeared granulated powder does not greatly collapse. Since the surface area of the disappearing granulated powder obtained by granulating the disappearing material is smaller than the surface area of the disappearing material before granulation, the disappearing granulated powder is difficult to accumulate. Moreover, since the affinity with the forming raw material powder is also improved, it is possible to obtain a foamable porous raw material in which the disappeared granulated powder is uniformly dispersed in the foamable forming raw material powder by mixing.
[0029]
By molding and firing the foamable porous forming raw material mixed as described above, a foamable porous member having pores that are granular and do not continue with other adjacent pores is obtained.
[0030]
Expandable porous compact can be molded by a dry made law. Therefore, any manufacturing method can be applied as long as it is a method suitable for the selected foamable molding raw material powder, such as a die press molding method, a rubber press method, and an extrusion molding method.
[0031]
Also, the firing of the foamable porous molded body is not particularly limited and can be performed by a usual method. For example, the dried molded body may be oxidized and fired in a tunnel kiln so that the maximum temperature becomes 1100 to 1300 ° C.
[0032]
The pores formed in this way are preferably granular and are not continuous with other adjacent pores. When the pores are uniformly dispersed and exist alone, there are more portions where the forming raw material powder is continuously present than those in which the pores are continuously present. Since the forming raw material powder plays the role of a column (or wall) in the fired porous member, the porous member having non-contiguous granular pores maintains the characteristics such as the shrinkage rate and strength of the forming raw material powder. be able to.
[0033]
In the foamable porous member according to the present invention, since the volume increase due to foaming of the foaming component is absorbed by the formed pores, the shrinkage after firing is approximately the same as that of the porous member not containing the foaming component, There is no big difference. As a result, in producing the foamable porous member according to the present invention, there is an advantage that an existing production facility, for example, a mold, a die, or the like can be used.
[0034]
In addition, a foamable porous member having moderately pores that are not continuous with each other has a slightly lower strength compared to the case without foaming because the volume increased by foaming is absorbed by the pores. It has enough strength to withstand. Therefore, it is possible to obtain a member having high strength while being a foamable porous member.
[0035]
[Test example]
The manufacturing method of the foamed porous member of the present invention will be described more specifically by the following test examples.
(Test Example 1)
The old newspaper was pulverized using a rotary tooth pulverizer. Thereafter, a pulverized product having a size of 0.5 mm or less was obtained using a JIS standard sieve. Water is added to the pulverized product and granulated using a high-speed fluidized mixer (Henschel mixer manufactured by Mitsui Mining Co., Ltd.). The granulated powder disappeared with a moisture content of 65% when granulated and 46% after natural drying ( Hereinafter referred to as a pore material). Table 1 shows the particle size distribution of the obtained pore material.
[0036]
[Table 1]

[0037]
As a foamable molding raw material powder in which a foamable component is blended with a molding raw material powder, a foamable ceramic raw material A (manufactured by Marumi Porcelain Co., Ltd. KEI-06) and a foamable ceramic raw material B (manufactured by Marumi Porcelain Co., Ltd.) C-1451) was blended with the lost granulated powder, which was the pore material obtained above, and uniformly mixed and dispersed with a mixer to obtain a foamable porous molding raw material. The mixing ratio of the pore material is 5 levels of 0, 10, 25, 30, 35 wt% for the foamable ceramic raw material A, and 4 of 0, 10, 25, 30 wt% for the foamable ceramic raw material B. Standard level. The mixer was mixed and dispersed for 30 seconds at a rotation speed of 500 rpm using a Kawata Super Mixer (SMV-20).
[0038]
Each obtained foamable porous molding raw material was molded into 75 mm × 75 mm (die size 82.5 mm × 82.5 mm) at a constant pressure using a hydraulic press to obtain four molded bodies for each level. The obtained molded body was dried at 110 ° C. for 3 hours, and then oxidized and fired at a maximum temperature of 1230 ° C. in a tunnel kiln to form a fired body (foamable porous member). The dimensional change rate was obtained. The results are shown in Table 2 (Foaming ceramic raw material A) and Table 3 (Foaming ceramic raw material B). The dimensional change rate is the dimensional change rate of the fired body with respect to the mold size, plus indicates an increase rate with respect to the mold size, and minus indicates a decrease rate.
[0039]
[Table 2]

[0040]
[Table 3]

[0041]
From Tables 2 and 3, it can be seen that the dimensions of the obtained fired body decrease linearly with an increase in the blending ratio of the pore material, but the bulk specific gravity is only slightly changed. This is because the pores formed by the disappearance of the pore material by firing absorb the volume increase due to foaming of the foaming component, and promote the shrinkage of components (ceramic raw material) other than the foaming component in the foamable ceramic raw material. Presumed to be because.
[0042]
By blending the pore material, volume increase due to foaming of the foamable ceramics is suppressed, and foamable ceramics with good shape can be obtained by the same molding method as in the past (when the pore material blending ratio is 0%). It was.
(Test Example 2)
The pore material was blended with a foamable ceramic raw material C (G-510F manufactured by Yamase Co., Ltd.) at 30% by weight of the same pore material as in Test Example 1, and uniformly mixed and dispersed by the same method as in Test Example 1. A foamable porous molding raw material was obtained. In addition, the foaming ceramic raw material C which does not mix | blend a pore material (mixing ratio: 0%) was made into the comparison material.
[0043]
The obtained foamable porous molding raw material and the comparative material were molded into 45 mm × 95 mm (die size 50 mm × 105.5 mm) at a constant pressure using a hydraulic press, and four molded bodies were obtained each. These molded bodies were dried at 110 ° C. for 3 hours and then oxidized and fired at a maximum temperature of 1240 ° C. in a tunnel kiln to form a fired body (foamable porous member). Were measured to determine the bulk specific gravity and the dimensional change rate. The results are shown in Table 4.
[0044]
[Table 4]

[0045]
From Table 4, by blending the pore material, the bulk specific gravity of the fired body (foamable porous member) is reduced, and the dimensional change rate is around -6%, and the volume expansion of the fired body is greatly suppressed. I understand.
(Test Example 3)
30% by weight of each of the foamable ceramic raw material A and the foamable ceramic raw material B as in Test Example 1 are mixed and dispersed uniformly by the same method as in Test Example 1, and the foamable porous molding raw material is mixed. It became.
[0046]
This foamable porous molding material was molded into 50 mm × 50 mm (die size 50 mm × 50 mm) at a constant pressure using a hydraulic press, and 12 molded bodies were obtained for each material. The obtained molded body was dried at 110 ° C. for 3 hours, and then oxidized and fired in an electric furnace (manufactured by Kyoei Electric Furnace) so that the maximum temperature would be 3 levels of 1185 ° C., 1220 ° C., and 1240 ° C. Four fired bodies (foamable porous members) were obtained for each raw material at a temperature. The dimensions and weight of these fired bodies were measured to determine the bulk specific gravity and the dimensional change rate. The results are shown in Table 5 (Foaming ceramic raw material A) and Table 6 (Foaming ceramic raw material B).
[0047]
[Table 5]

[0048]
[Table 6]

[0049]
Generally, when a molded body made of a foamable ceramic material is fired, if the firing temperature is different, the degree of foaming of the foaming component in the foamable ceramic material is different. (Volume increase). However, in this test example, even if the firing temperature was different, the pores formed by firing absorbed the volume increase of the foamed component, so the dimensional change rate of the fired body was negative (volume decrease) regardless of the firing temperature. became. That is, it can be seen that the change in the dimensional change rate of the fired body due to the change in the firing temperature is extremely small.
[0050]
【The invention's effect】
According to the method for producing a foamable porous member of the present invention, it is possible to obtain a foamable porous member that is less affected by the firing temperature condition and has stable properties. Therefore, it is possible to design with high accuracy with respect to product quality such as dimensions after firing, and the desired quality can be obtained. For this reason, productivity can be improved while improving the quality of a foamable porous member.
[0051]
Conventional foamable porous members have a problem in shape stability due to unstable volume expansion of foamed components. However, in the present invention, since the foamable porous member whose size is contracted can be obtained, the shape stability of the product is greatly improved.
[0052]
Moreover, the shrinkage rate of a foamable porous member can be adjusted by changing the mixture ratio of the disappearance granulated powder. Therefore, a foamable porous member having the same dimensional change rate as that of the conventional product can be obtained, and existing equipment and glazes can be applied as they are, which is efficient.
[0053]
The method for producing a foamable porous member of the present invention can be particularly suitably applied to the production of large composite tiles or building materials having excellent heat insulation and light weight such as heat insulating bricks and light blocks, It has a great effect on stability and productivity improvement.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view showing a state in which lost granulated powder disappears and pores are formed by heating.
FIG. 2 is an explanatory diagram for explaining how the increased volume is absorbed by the pores being reduced even when the volume is increased due to foaming of the foam component.
[Explanation of symbols]
1: Foaming component 2: Molding raw material 3: Pore

Claims

A foaming raw material powder obtained by granulating a foaming molding raw material powder containing a foaming component that foams by heating into a molding raw material powder, and having a moisture content of 40 to 50% by weight obtained by granulating the disappearing material that disappears by heating, Mixing 10 to 50% by weight of the forming raw material powder as 100% by weight to form a foamable porous molding raw material, molding the foamable porous molding raw material into a molded body of a predetermined shape, and firing the molded body By
The pores independent from each other formed by the disappearance of the disappeared granulated powder absorb the volume increase of the foam component due to foaming, and suppress the volume change before and after firing of the molded body. A method for producing a foamable porous member.

The method for producing a foamable porous member according to claim 1, wherein the disappearing material is an organic substance.

The method for producing a foamable porous member according to claim 2, wherein the organic substance is paper.

2. The foamable porous member according to claim 1, wherein the vanishing granulated powder has a granular shape having a thickness of 3 or less when the thinnest portion is 1 in the thickness passing through the center of the vanishing granulated powder. Manufacturing method.

The method for producing a foamable porous member according to claim 1, wherein the forming raw material powder is at least one of ceramic raw material powder and metal powder .

The method for producing a foamable porous member according to claim 5 , wherein the ceramic raw material powder is at least one of clay, porcelain stone, wax stone, silica stone, lime, feldspar, talc, silicon nitride, and silicon carbide .

A foaming raw material powder obtained by granulating a foaming molding raw material powder containing a foaming component that foams by heating into a molding raw material powder, and having a moisture content of 40 to 50% by weight obtained by granulating the disappearing material that disappears by heating, A foaming porous molding raw material is formed by blending 10 to 50% by weight of the molding raw material powder as 100% by weight, forming the foamable porous molding raw material into a molded body having a predetermined shape, and firing the molded body. Where
A foaming porous material having pores independent of each other and having a dimensional change rate of the molded body after firing with respect to a mold size of the molded body being −1.20% to −8.48% Quality material .