JP4576801B2 - Radio wave absorbing ceiling panel, method for manufacturing the same, and method for preventing indoor wireless communication failure using the same - Google Patents

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【００５６】
【表２】

【００５７】
＜表１及び表２の評価測定方法＞
曲げ強度：ＪＩＳ Ａ １４０８（５号試験体）法による。
熱抵抗 ：ＪＩＳ Ａ １４２０法による。
防火性能：ＪＩＳ Ａ １３２１法による。
吸音率 ：ＪＩＳ Ａ １４０９（残響室）法による。
電波遮蔽性能：各試験毎の厚さ９〜１５ｍｍ、縦横の長さが４００ｍｍ×４００ｍｍの試験体のみを、電波送信アンテナと受信アンテナの間に設置し、タイムドメイン法により透過レベルを測定する。透過係数は、試験体を設置しない場合の透過レベルとの対比にて算出し電波遮蔽性能とした。
電波吸収性能：日本建築学会にて検討を進めている「電波吸収体性能評価計測方法」に従い、各試験毎の厚さ９〜１５ｍｍ、縦横の長さが４００ｍｍ×４００ｍｍの試験体の裏面に、縦横の長さが４００ｍｍ×４００ｍｍの金属板を貼り合わせたものを用い、自由空間タイムドメイン法による反射係数を測定。反射係数は、金属板のみの反射レベルとの対比にて算出し電波吸収性能とした。
【００５８】
《表１及び表２の実施例と比較例との対比》
１．曲げ強度については、いずれも内装天井板としての適性値を示している。
２．熱抵抗については、いずれも充分な断熱性をしめし、優位差はない。
３．防火性については、実施例１〜９及び実施例１１、及び比較例１〜２は不燃、実施例１０は準不燃で合格。
４．吸音率については、実施例１〜１１、ならびに比較例１〜２において、いずれも適性な吸音率を示し、優位差はない。
５．電波遮蔽性能は、実施例１〜８および実施例１０〜１１、ならびに比較例２において２〜５．５ｄＢの遮蔽性能を示しているが、一般的な電波遮蔽材としての充分な性能は有していない。実施例９において、３１ｄＢ以上の遮蔽性能を示しており、一般的な電波遮蔽材としての充分な性能である３０ｄＢ以上を満たしている。比較例１では、電波遮蔽性能は示していない。
６．電波吸収性能については、実施例１〜１１において２．４５ＧＨｚで６〜１５ｄＢ、５．１ＧＨｚで６〜１２ｄＢを示しており、無線ＬＡＮシステム用として用いられる２．４ＧＨｚ帯及び５ＧＨｚ帯でのオフィス内等での無線通信において、通信障害対策として、十分な吸収性能を有している。一方導電物質としてのカーボンファイバーを配合していない比較例１の場合、吸収性能が得られず前記条件を満たしていない。又、比較例２においては、カーボンファイバーが高配合のため、電波反射の影響を受け、充分な吸収性能を示していない。
【００５９】
実施例１〜１１及び比較例１〜２については、前記日本建築学会にて検討を進めている「電波吸収体性能評価計測方法」に従い、金属板に試験体を貼り合わせた状態で電波吸収を測定している。このため、共振による電波吸収性能と試験体そのものが持つ内部損失による電波吸収性能が混在した状態で電波吸収性能が測定され、裏面に電波反射体を有さない電波吸収体の測定における試験体そのものが持つ内部損失による電波吸収性能を測定しづらいということが解った。本発明者は、試験体が持つ内部吸収特性をより正確に測定し、共振現象による吸収性能との差異をより明確に表現するために、鋭意検討した結果、試験体と金属板との間に空間を持たせることにより、共振現象の発生を防止できることを見出し、４００ｍｍ×４００ｍｍの金属板の前面に１００ｍｍの空間を設けて試験体を設置し、金属板と試験体が一体化しないようにして共振現象が発生しない状態とし、自由空間タイムドメイン法による反射係数を測定した。反射係数は、金属板のみの反射レベルとの対比にて算出し電波吸収性能とした。つづいて試験体の裏面にアルミ箔を張った構造とし、共振現象が発生する状態としたものについても、自由空間タイムドメンイン法による反射係数を測定した。この方法により、より実効性の高い電波吸収性を測定することができる。
【００６０】
以下、本発明の不燃吸音電波吸収性の天井板に関し、前記共振現象を生じさせない条件と裏面にアルミ箔を貼った共振現象を生じさせる条件との対比を含めて、以下実施例１２〜１９、比較例３および参考例１〜２により説明する。
【００６１】
＜実施例１２＞
ＳｉＯ₂４１ｗｔ％、ＣａＯ３６ｗｔ％、ＭｇＯ６ｗｔ％、Ａｌ₂Ｏ₃１２ｗｔ％、その他Ｎａ₂Ｏ、Ｋ₂Ｏ等の微量成分５ｗｔ％の組成からなる繊維長１００〜５００μｍの鉄鋼スラグ系ロックウール８９．７５ｗｔ％、パルプを水に分散しリファイナーで叩解した叩解パルプ１ｗｔ％、澱粉５．５ｗｔ％、水に分散して解繊したアタパルジャイト２．８５ｗｔ％、１５％濃度ポリアクリルアミド水溶液０．２ｗｔ％（固形分ベース）、硫酸アルミニウム０．６ｗｔ％、前処理として水中に１ｗｔ％の割合で投入し、２００回転／分の回転速度で２分間ミキサーにて攪拌した、繊維長４ｍｍのカーボンファイバー（大阪ガス（株）製；ザイラス）を０．１ｗｔ％（固形分ベース）を加えて混合し、ミキサーで分散して約５ｗｔ％濃度の水性スラリーを調整する。該スラリーを長網抄造機で抄造し脱水乾燥して原板を製造する。さらにこの原板の表面を切削加工して板厚１２ｍｍ、嵩密度０．４ｇ／ｃｍ³の内装用天井板のパネルＮを得た。パネルＮの強度、防火性、熱伝導率、吸音率、電波遮蔽性能、電波吸収性能等を表３に示す。表３に示すとおり、実施例１２では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合も６ｄＢ以上の良好な電波吸収性能を有している。
【００６２】
＜実施例１３＞
実施例１２のカーボンファイバーの配合割合を０．４０ｗｔ％、ロックウールの配合割合を８９．４５ｗｔ％とし、その他は実施例１２と同一設定条件で内装用天井板のパネルＯを得た。パネルＯの性能等を表３に同じく示す。表３に示すとおり、実施例１３では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合も６ｄＢ以上の良好な電波吸収性能を有している。
【００６３】
＜実施例１４＞
実施例１２のカーボンファイバーの配合割合を０．３ｗｔ％、ロックウールの配合割合を８９．５５ｗｔ％とし、その他は実施例１２と同一設定条件で内装用天井板のパネルＰを得た。表面を切削加工した板厚９ｍｍのパネルＰの性能等を表３に同じく示す。表３に示すとおり、実施例１４では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合も６ｄＢ以上の良好な電波吸収性能を有している。
【００６４】
＜実施例１５＞
実施例１２のカーボンファイバーの配合割合を０．１５ｗｔ％、ロックウールの配合割合を８９．７ｗｔ％とし、その他は実施例１と同一設定条件で内装用天井板のパネルＱを得た。表面を切削加工した板厚１５ｍｍのパネルＱの性能等を表３に同じく示す。表３に示すとおり、実施例１５では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合も６ｄＢ以上の良好な電波吸収性能を有している。
【００６５】
＜実施例１６＞
実施例１２のカーボンファイバーの濃度を０．３ｗｔ％とし、ロックウールの配合割合を８９．５５ｗｔ％とし、その他は実施例１２と同一設定条件で嵩密度が０．５ｇ／ｃｍ³となるように内装用天井板のパネルＲを得た。パネルＲの性能等を表３に同じく示す。表３に示すとおり、実施例１６では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合も６ｄＢ以上の良好な電波吸収性能を有している。
【００６６】
＜実施例１７＞
実施例１２のカーボンファイバー長さを１２ｍｍ、濃度を０．１８ｗｔ％とし、ロックウールの配合割合を８９．６７ｗｔ％とし、その他は実施例１２と同一設定条件で内装用天井板のパネルＳを得た。パネルＳの性能等を表３に同じく示す。表３に示すとおり、実施例１７では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合でも６ｄＢ以上の良好な電波吸収性能を有している。
【００６７】
＜実施例１８＞
ロックウール８６．１ｗｔ％、ジェル３ｗｔ％、ポリビニルアルコール７ｗｔ％、アタパルジャイト３ｗｔ％、１５％濃度ポリアクリルアミド水溶液０．２ｗｔ％（固形分ベース）、硫酸アルミニウム０．６ｗｔ％、繊維長４ｍｍのカーボンファイバー（大阪ガス（株）製；ザイラス）を０．１ｗｔ％（固形分ベース）をからなる混合をミキサーで分散し、約５ｗｔ％濃度の水性スラリーを調整する。該スラリーを長網抄造機で抄造し脱水乾燥して原板を製造する。さらにこの原板の表面を切削し内装天井板としての充分な強度を有する内装用天井板のパネルＴを得た。パネルＴの強度、防火性、熱伝導率、吸音率、電波遮蔽性能、電波吸収性能等の性能を表４にまとめた。表４に示すとおり、実施例１８では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合も６ｄＢ以上の良好な電波吸収性能を有している。
【００６８】
＜実施例１９＞
ロックウール６１．１ｗｔ％、ジェル３ｗｔ％、ポリビニルアルコール７ｗｔ％、アタパルジャイト３ｗｔ％、１５％濃度ポリアクリルアミド水溶液０．２ｗｔ％（固形分ベース）、硫酸アルミニウム０．６ｗｔ％、水酸化アルミニウム２５ｗｔ％、繊維長４ｍｍのカーボンファイバー（大阪ガス（株）製；ザイラス）を０．１ｗｔ％（固形分ベース）をからなる混合をミキサーで分散し、約５ｗｔ％濃度の水性スラリーを調整する。該スラリーを長網抄造機で抄造し脱水乾燥して原板を製造する。さらにこの原板の表面を切削し内装天井板としての充分な強度を有する内装用天井板のパネルＵを得た。パネルＵの強度、防火性、熱伝導率、吸音率、電波遮蔽性能、電波吸収性能等の性能を表４にまとめた。表４に示すとおり、実施例１９では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合も６ｄＢ以上の良好な電波吸収性能を有している。
【００６９】
［比較例３］
ロックウール８９．８５ｗｔ％、ジェル１ｗｔ％、澱粉５．５ｗｔ％、アタパルジャイト２．８５ｗｔ％、１５％濃度ポリアクリルアミド水溶液０．２ｗｔ％（固形分ベース）、硫酸アルミニウム０．６ｗｔ％からなる混合をミキサーで分散し、約５ｗｔ％濃度の水性スラリーを調整する。該スラリーを長網抄造機で抄造し脱水乾燥して原板を製造する。さらにこの原板の表面を切削し内装天井板としての充分な強度を有する内装用天井板のパネルＶを得た。パネルＶの強度、防火性、熱伝導率、吸音率、電波遮蔽性能、電波吸収性能等の性能を表４にまとめた。表４に示すとおり、比較例３では裏面にアルミ箔を張りつけた場合も、裏面のアルミ箔を張りつけない場合も電波吸収性能を有していない。
【００７０】
［参考例１］
ロックウール８９．８０ｗｔ％、ジェル１ｗｔ％、澱粉５．５ｗｔ％、アタパルジャイト２．８５ｗｔ％、１５％濃度ポリアクリルアミド水溶液０．２ｗｔ％（固形分ベース）、硫酸アルミニウム０．６ｗｔ％、繊維長４ｍｍのカーボンファイバー（大阪ガス（株）製；ザイラス）０．０５ｗｔ％からなる混合をミキサーで分散し、約５ｗｔ％濃度の水性スラリーを調整する。該スラリーを長網抄造機で抄造し脱水乾燥して原板を製造する。さらにこの原板の表面を切削し内装天井板としての充分な強度を有する内装用天井板のパネルＷを得た。パネルＷの強度、防火性、熱伝導率、吸音率、電波遮蔽性能、電波吸収性能等の性能を表４にまとめた。表４に示すとおり、参考例１では裏面にアルミ箔を張りつけた場合は所望の電波吸収性能をえられたが、裏面のアルミ箔を張りつけない場合は十分な電波吸収性能を得られない。
【００７１】
［参考例２］
ロックウール８９．２５ｗｔ％、ジェル１ｗｔ％、澱粉５．５ｗｔ％、アタパルジャイト２．８５ｗｔ％、１５％濃度ポリアクリルアミド水溶液０．２ｗｔ％（固形分ベース）、硫酸アルミニウム０．６ｗｔ％、繊維長４ｍｍのカーボンファイバー（大阪ガス（株）製；ザイラス）０．６ｗｔ％からなる混合をミキサーで分散し、約５ｗｔ％濃度の水性スラリーを調整する。該スラリーを長網抄造機で抄造し脱水乾燥して原板を製造する。さらにこの原板の表面を切削し内装天井板としての充分な強度を有する内装用天井板のパネルＸを得た。パネルＸの強度、防火性、熱伝導率、吸音率、電波遮蔽性能、電波吸収性能等の性能を表４にまとめた。表４に示すとおり、参考例２では裏面にアルミ箔を張りつけた場合、裏面のアルミ箔を張りつけない場合いずれも６ｄＢ以上の十分な電波吸収性能を得られていない。
【００７２】
【表３】

【００７３】
【表４】

【００７４】
＜表３及び表４の評価測定方法＞
曲げ強度：ＪＩＳ Ａ １４０８（５号試験体）法による。
熱抵抗 ：ＪＩＳ Ａ １４２０法による。
防火性能：ＪＩＳ Ａ １３２１法による。
吸音率 ：ＪＩＳ Ａ １４０９（残響室）法による。
電波遮蔽性能：各試験毎の厚さ９〜１５ｍｍ、縦横の長さが４００ｍｍ×４００ｍｍの試験体のみを、電波送信アンテナと受信アンテナの間に設置し、タイムドメイン法により透過レベルを測定する。透過係数は、試験体を設置しない場合の透過レベルとの対比にて算出し電波遮蔽性能とした。
電波吸収性能：反射電波からの共振現象を防止し、試験体そのものが持つ内部損失による電波吸収性能のみを測定するため、縦横の長さが４００ｍｍ×４００ｍｍの金属板の前面に１００ｍｍの空間を設けて各試験毎の厚さ９〜１５ｍｍ、縦横の長さが４００ｍｍ×４００ｍｍの試験体を設置し、電波反射による共振現象が発生しない状態で自由空間タイムドメイン法による反射係数を測定。反射係数は、金属板のみの反射レベルとの対比にて算出し電波吸収性能とした。つづいて試験体裏面にアルミ箔を貼った構成の試験体とし、電波反射による共振現象が発生する状態としたものについても、自由空間タイムドメイン法による反射係数を測定した。
【００７５】
《表３及び表４の実施例と比較例との対比》
１．曲げ強度については、いずれも内装天井板としての適性値を示している。
２．熱抵抗については、いずれも充分な断熱性をしめし、優位差はない。
３．防火性については、実施例１２〜１７及び実施例１９、及び比較例３、参考例１〜２は不燃、実施例１８は準不燃で合格。
４．吸音率については、実施例１２〜１９、比較例３および参考例１〜２において、いずれも適性な吸音率を示し、優位差はない。
５．電波遮蔽性能は、アルミ箔無しの条件で実施例１２〜１９、並びに参考例１〜２において２〜６．８ｄＢの遮蔽性能を示しているが、一般的な電波遮蔽材としての充分な性能は有していない。比較例３では、電波遮蔽性能はほとんど示していない。
６．電波吸収性能についてば、実施例１２〜１９において、裏面にアルミ箔を一体化した場合、及び裏面にアルミ箔を一体化しない場合のいずれにおいても、２．４５ＧＨｚで６〜９ｄＢ、５．１ＧＨｚで６〜９ｄＢを示しており、無線ＬＡＮシステム用として用いられる２．４ＧＨｚ帯及び５ＧＨｚ帯でのオフィス内等での無線通信において、通信障害対策として、十分な吸収性能である６ｄＢ以上をいずれも満たしている。従って、実施例１２〜１９のカーボンファイバー配合の条件では、裏面にアルミ箔を一体化しない場合においても良好な電波吸収性能が得られることを示している。一方導電物質としのカーボンファイバーを配合していない比較例３の場合、吸収性能が得られていない。又、参考例１においては、カーボンファイバーが低配合のため、裏面にアルミ箔を張り合わせた場合は共振現象による電波損失の付加により所望の電波吸収性能を示すが、裏面にアルミ箔を張り合わせない場合は充分な吸収性能を示さず、参考例２においては、カーボンファイバーが高配合のため、裏面にアルミ箔を張り合わせない場合でも電波反射の影響を受け、充分な吸収性能を示していない。
【００７６】
実施例２０
上記参考例１記載の天井板におけるカーボンファイバー配合量のみを種々変えた天井板に、それぞれ繊維長０．７ｍｍのピッチ系カーボンファイバーを種々の配合量で含有する酢酸ビニル系エマルジョン塗料（ポリ酢酸ビニル系ＰＣコート）を６２５ｇ／ｍ²の量でローラーコート塗布することにより、各天井板を得た。各天井板の表面および裏面（ＰＣコート中）のカーボンファイバーの配合量およびその電波吸収性能を表５に示す。
なお、電波吸収性能の測定は、実施例１２〜１９と同様の方法で測定した。
【００７７】
【表５】

【００７８】
表５の結果から、表面のカーボンファイバー配合量（特に「ＣＦ１」と称する）が０．１０ｗｔ％以上であればＰＣコート中にカーボンファイバーを配合しなくても非常に優れた電波吸収性能が得られるが、ＣＦ１が０．０８ｗｔ％以下の配合量の場合には、アルミ箔を貼らない構造では十分な電波吸収性能が得られない。これに対して、ＣＦ１が低配合量の場合であっても、それより多量のカーボンファイバーを配合するＰＣコート（ＰＣコート中の配合量を特に「ＣＦ２」と称する）を裏面に塗布することにより、顕著に電波吸収性能が向上することがわかる。
【００７９】
特に、両者の配合量を工夫することにより、無線通信用途（無線ＬＡＮ）に好適な吸収性能である６ｄＢ以上の吸収性能が得られる。特に表面側天井板のカーボンファイバー配合量（ＣＦ１）が０．０４ｗｔ％〜０．０８ｗｔ％、ＰＣコート中の配合量（ＣＦ２）が１．０ｗｔ％〜１５．０ｗｔ％において、上記好適な吸収性能が得られる。
【００８０】
【発明の効果】
以上述べたように、本発明の不燃吸音電波吸収性の天井板は、軽量で準不燃から不燃の防火性能を備え、吸音性、断熱性、電波吸収性を合わせ持ち、低コストでしかも充分な曲げ強度を有するため、建築物の構造及び建築部材としての多様な機能ニーズに好適に対応できる不燃吸音電波吸収性の天井板としての効果を有する。
【００８１】
また、前記不燃吸音電波吸収性の天井板において、カーボンファイバーを含まない層と、カーボンファイバーを含む二層の積層構成を採用することにより、施工後の室内側表面に意匠的効果を付加させた内装用天井板を得ることができる。
【００８２】
更に、不燃吸音電波吸収性の金属箔貼り天井板を採用した場合には、反射電波の共振現象による電波吸収を付加向上した電波吸収効果に加え、電波遮蔽性を付加向上する効果を有する。
【００８３】
本発明の不燃吸音電波吸収性の天井板は、前記繊維長１〜３０ｍｍのカーボンファイバーの配合割合を０．０８〜０．４ｗｔ％とすることにより、反射電波からの共振現象による電波吸収性を付加せずとも、優れた電波吸収性能を得ることができ、特に無線通信用途（無線ＬＡＮ）の好適電波吸収性能、特に６ｄＢ以上の電波吸収性能を得ることができる効果を有する。
【００８４】
さらに、前記繊維長１〜３０ｍｍのカーボンファイバーの配合割合を０．０４〜０．０８ｗｔ％とし、さらにその裏面に該カーボンファイバー配合量よりも多量にカーボンファイバーを配合する有機系塗料を塗布することによっても、優れた電波吸収性能を得ることができ、特に無線通信用途の好適吸収性能を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention is lightweight and has sufficient bending strength, incombustibility, sound absorption, heat insulation, radio wave absorption, and non-combustion sound absorption radio wave absorption ceiling plate for the purpose of design, and further to the ceiling plate The present invention relates to a nonflammable radio wave absorptive metal foil-clad ceiling board that has been subjected to a metal foil pasting process to improve radio wave shielding, and a ceiling board in which an organic paint containing carbon fiber is applied to the back surface.
[0002]
[Prior art]
Wireless communication devices such as mobile phones and PHS have been widely used, and wireless communication devices used in wireless data communication networks called wireless LANs are rapidly spreading in offices, stores, factories and warehouses. When such a wireless communication device is used in a specific indoor space such as an office, metal foil or the like is used for the purpose of preventing intrusion of noise radio waves from the outside or preventing indoor information from leaking outside. A technique for constructing a radio wave shield made of mesh, conductive fiber, or the like is known.
[0003]
However, when such a radio wave shield is installed, the radio wave reflectivity in the room is increased, and the radio wave transmitted from the wireless communication device is reflected from the interior wall, ceiling, floor, and steel furniture fittings, Reflected waves with different phases arrive at the receiving terminal, or multiple reflected waves arrive from the ceiling, wall, floor, etc. and cannot be recognized as a normal signal on the receiver side, resulting in an abnormally long communication time. There is a problem that disables communication. Even if the radio wave shield is not intentionally installed, recent offices may use metal deck plates on the ceiling and floor, or metal double floor panels on the floor. In many cases, the upper and lower surfaces have an electromagnetic wave reflection environment. As for the wall surface, there are many cases in which a steel partition wall is used, and the case where the wall surface becomes a radio wave reflector is increasing.
[0004]
In such an indoor environment, as in the case where the radio wave shield is intentionally constructed, communication due to a transmission abnormality caused by reflected waves having different phases when a wireless communication device is used, or communication due to the influence of reflected waves that arrived with a delay in time. Failure can occur. As a countermeasure against this phenomenon, it is effective to install a member that suppresses the reflection of radio waves in the interior material of the room. Conventionally, cement tiles or gypsum boards containing ferrite tiles, ferrites or conductive materials have been used. Yes. In addition, a construction method has been proposed in which a felt-shaped electromagnetic wave absorber is integrated with the back surface of a ceiling or floor or a base board.
[0005]
[Problems to be solved by the invention]
However, in addition to the complexity of the conventional construction method, cement tiles and gypsum boards containing ferrite tiles, ferrites, or conductive materials have a large specific gravity, which is troublesome for construction and expensive. Yes. In addition, in order to prevent the reflection of radio waves, it is often the case that a steel desk is installed on the floor for the floor surface when it is assumed that construction is performed on the floor and wall parts of the interior building materials. As a result, the floor surface becomes a radio wave reflector, which often impairs the radio wave absorption effect of the radio wave absorber constructed on the floor surface. In addition, when an electromagnetic wave absorber is constructed on the wall surface, there are many cases where a steel bookcase or locker is installed on the front surface of the wall after construction. There are many cases of loss.
[0006]
On the other hand, when a radio wave absorber is constructed on the ceiling surface, there is no case where a radio wave reflector is constructed on the indoor side of the ceiling surface after construction, and a steel desk or bookcase is installed in the room. Even if the usage situation changes, the radio wave absorption performance of the ceiling surface is rarely impaired. In addition, wireless LAN transmission / reception devices are often installed on a desk or a personal computer on a desk, and the transmitted radio waves are often reflected by the ceiling surface. It is preferable to install a radio wave absorber on the surface.
[0007]
However, in the conventional construction method, ferrite tiles, ferrite-containing gypsum boards, etc. are not only difficult to construct because they are high specific gravity materials, but also costly, the board color becomes black, and earthquake resistance, etc. There is also a problem in terms of.
[0008]
The present invention has been made in view of the above situation, and as a ceiling board for interiors, which is the most suitable part for solving wireless LAN communication problems, it is lightweight and has sufficient bending strength, incombustibility, sound absorption, and heat insulation. The ceiling plate for interiors has a favorable radio wave absorption performance condition and has a design property taken into consideration, and the ceiling plate is further improved by adding metal foil to the ceiling plate to improve radio wave shielding. The purpose is to obtain.
[0009]
[Means for Solving the Problems]
The desired interior ceiling board is composed of rock wool that imparts incombustibility, sound absorption and heat insulation, beating pulp called organic gel for imparting strength and water resistance, an organic binder, and binding during papermaking Flocculants for imparting material collection and strength, natural mineral fibers for improving panel dimensional stability and appearance, surface smoothness and strength, and organic water repellents for imparting water repellency It has been found that a mixture obtained by mixing a carbon fiber for imparting radio wave absorbability with water is dispersed in water to form a slurry, which is produced by wet papermaking.
[0010]
That is, the present invention includes rock wool 67 to 92 wt%, beaten pulp 0.5 to 8 wt%, binder 2 to 13 wt% composed of organic resin, flocculant 0.15 to 1 wt% composed of organic polymer resin and inorganic salt, A ceiling board having a thickness of 1 to 30 mm, obtained by wet-making a water-dispersed slurry of a mixture of natural mineral fibers 0.5 to 10 wt% and carbon fibers 0.02 to 1 wt% having a fiber length of 1 to 30 mm, It is a means for solving problems.
[0011]
As an invention for the purpose of design, it comprises rock wool 67 to 92 wt%, beating pulp 0.5 to 8 wt%, a binder 2 to 13 wt% made of an organic resin, an organic polymer resin and an inorganic salt. A layer obtained by wet-making a water-dispersed slurry of a primary mixture containing 0.15 to 1 wt% of a flocculant and 0.5 to 10 wt% of natural mineral fibers, and a fiber length of 1 for the primary mixture An incombustible sound absorbing radio wave absorbing ceiling board having a thickness of 1 to 30 mm, comprising a layered structure obtained by wet-making a water dispersion slurry of a secondary mixture further containing 0.02 to 1 wt% of carbon fiber of ˜30 mm. It is a means for solving problems.
[0012]
The carbon fiber blended in the non-combustible sound absorbing radio wave absorbing ceiling board is put into water at a rate of 0.5 to 2 wt% as a pretreatment, and the rotation speed is 0.5 to 500 with a mixer at 100 to 400 rpm. Stirring for 3 minutes is also a suitable means.
[0013]
It is also preferable to add 50 wt% or less of an additive such as an inorganic filler in the form of replacing rock wool blended as a main component of the non-combustible sound absorbing radio wave absorbing ceiling board.
[0014]
In order to improve the radio wave shielding of the non-combustible sound-absorbing radio wave absorbing ceiling plate and to improve the radio wave absorption due to the resonance phenomenon of the reflected radio wave, the non-combustible sound-absorbing radio wave absorbing metal foil-attached ceiling plate also has a metal foil attached to the back surface. This is a suitable means.
[0015]
On the other hand, the radio wave absorption performance is effectively exhibited under the condition that the metal foil or the metal plate is not disposed on the back surface of the non-combustible sound absorbing radio wave absorbing ceiling plate, that is, the resonance phenomenon of the radio wave reflected by the metal foil or the metal plate. When the amount of radio wave absorption generated by the above is not added, a preferable radio wave absorption performance can be obtained by setting the blending ratio of carbon fibers having a fiber length of 1 to 30 mm to 0.08 to 0.4 wt%.
[0016]
Moreover, even if the carbon fiber blending amount is 0.04 to 0.08 wt%, it is more on the back surface of the ceiling board than the blending amount, preferably 1.0 to 15.0 wt%. 100 to 3000 g / m of organic paint blended with carbon fiber ² By applying in this amount, a suitable radio wave absorption performance similar to the above can be obtained even under conditions where no metal stays or metal plates are arranged on the back surface of the ceiling plate.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the nonflammable sound absorbing radio wave absorbing ceiling plate of the present invention will be described.
The rock wool constituting the present invention is SiO ₂ 35-55 wt%, Al ₂ O _Three 10-20 wt%, MgO 5-40 wt%, CaO 5-40 wt%, FeO 0-10 wt%, Na ₂ O, K ₂ O, TiO ₂ It is obtained by melting a raw material mineral mixture containing trace components of 0 to 10 wt% such as MnO in a cupola furnace or an electric furnace and fiberizing it by a blowing method or a spinning method using a high-speed rotating body. The fiber is wooly and the fiber length is in the range of several millimeters to several tens of millimeters.
[0018]
The blending ratio of the rock wool is appropriate in the range of 67 to 92 wt% in relation to nonflammability, sound absorption, and strength, and if it is less than 67 wt%, the organic binder ratio is relatively high, so that it is nonflammable. -Sound absorption is impaired, and if it exceeds 92 wt%, the ratio of the organic binder is relatively reduced and the bending strength as an interior ceiling board becomes insufficient.
[0019]
The blending ratio of the beating pulp is in the range of 0.5 to 8 wt% in relation to nonflammability, drainage during paper making, and strength as a ceiling plate for interior, and the strength of the ceiling plate is less than 0.5 wt%. If the amount exceeds 8 wt%, nonflammability and drainage during production deteriorate, and fire resistance and productivity are impaired.
[0020]
Substances used as the organic binder include starch, polyvinyl alcohol, polyethylene, paraffin powder, etc., phenol resin, melamine resin, thermosetting powder resin such as epoxy resin, acrylic resin, modified acrylic resin, polyvinyl acetate, Examples thereof include organic binders such as emulsions of ethylene / acetic acid copolymer resins, polyvinylidene chloride resins, modified polyvinylidene chloride resins, epoxy resins, urethane resins and the like. The blending amount of these organic binders is appropriately 2 to 13 wt% in relation to nonflammability and strength. If it exceeds 13 wt%, the nonflammability is impaired, and if it is less than 2 wt%, the bending strength is insufficient. However, 13-20 wt% of organic binder can be added by adding aluminum hydroxide in the form of replacing rock wool.
[0021]
Since the present invention is produced by a wet papermaking method, it is necessary to add a small amount of an aggregating agent such as polyacrylamide or sulfuric acid band that effectively retains the organic binder. The blending amount of the polymer flocculant is preferably in the range of 0.15 to 1 wt% in view of strength effect and nonflammability.
[0022]
In the present invention, it is necessary to add natural mineral fibers such as attapulgite and sepiolite for the purpose of improving strength, dimensional stability, and moisture deflection resistance. The range of 0.5 to 10 wt% is appropriate due to the relationship between the drainage and the strength involved in the productivity at the time of wet papermaking, and if it exceeds 10 wt%, the drainage time becomes longer and the productivity is impaired. If it is less than the range, the dimensional stability and moisture deflection resistance are insufficient.
[0023]
In the present invention, it is necessary to add a small amount of a water repellent such as wax emulsion or silicone resin emulsion in order to impart water repellency. The blending ratio of the water repellent is preferably in the range of 0.1 to 0.5 wt% from the relationship between water repellency, strength and nonflammability.
[0024]
In the configuration of the present invention, a fibrous conductive material is blended as a component that imparts radio wave absorption performance. The fibrous conductive material is preferably a PAN-based or pitch-based carbon fiber with a fiber length in the range of 1 to 30 mm. Representative examples include Zyrus manufactured by Osaka Gas Co., Ltd., trading card manufactured by Toray Industries, Inc. and Besfight manufactured by Toho Rayon Co., Ltd. The longer the fiber length of the carbon fiber, the better the radio wave absorption performance with a small blending amount, but the carbon fiber becomes entangled and dispersed when it is dispersed in water during paper making and the dispersion becomes worse, and the radio wave absorption performance decreases. Therefore, the fiber length is preferably 30 mm or less. When the thickness is less than 1 mm, there is no problem in dispersibility, but it is difficult to obtain the dielectric loss effect which is the principle of radio wave absorption, and the radio wave absorption performance is lowered.
[0025]
It has been found that the blending ratio of the carbon fiber exhibits good radio wave absorption performance at 0.02 wt% or more. Here, if it exceeds 1 wt%, the characteristics of the radio wave reflectivity are excessively improved and the radio wave absorption performance may be deteriorated. Therefore, the range of 0.02 to 1 wt% is preferable. It is presumed that the blended carbon fiber acts as a dielectric, causes radio wave energy loss due to dielectric loss in a frequency band of gigahertz or higher, and exhibits desired radio wave absorption performance.
[0026]
The incombustible sound absorbing radio wave absorbing ceiling board of the present invention is a mixture of rock wool, an organic binder, a binding aid and carbon fiber dispersed in water, and is used for paper making such as a circular net or a long net type, a rot former. It is obtained by making a wet mat with a paper making machine, drying and curing, and cutting and cutting into an arbitrary shape. The main components and the production method of the present invention are as described above, but it is possible to add a small amount of a flame retardant or an inorganic substance to the organic binder for the purpose of improving fire resistance and reducing costs.
[0027]
The thickness of the ceiling board of the present invention is 1 to 30 mm, preferably 9 to 19 mm. Moreover, the bulk density of the ceiling board is 0.3 to 0.5 g / cm. ^Three Is preferred.
[0028]
In the incombustible sound absorbing radio wave absorbing ceiling plate of the present invention, there is a laminated ceiling plate composed of at least two layers of a layer not containing carbon fiber and a layer containing carbon fiber. The ceiling board is made of rock wool 67 to 92 wt%, beaten pulp 0.5 to 8 wt%, binder 2 to 13 wt% made of organic resin, and flocculant 0.15 made of organic polymer resin and inorganic salt. First, a primary mixture in which ˜1 wt% and natural mineral fiber 0.5 to 10 wt% are mixed is first formed into a layer, and then carbon fiber having a fiber length of 1 to 30 mm is formed on the mixture by 0.02 to 1 wt%. Form the water dispersion slurry of the blended secondary mixture in layers, or form the water dispersion slurry of the secondary mixture obtained by blending the carbon fibers at a ratio of 0.02 to 1 wt% first. In addition, it can be obtained by any one of wet papermaking, in which the aqueous dispersion slurry of the primary mixture is layered to form a layer.
[0029]
When carbon fiber is included, although depending on the amount of the carbon fiber, the black color of the fiber appears on the surface in a linearly dispersed state, which may be undesirable, particularly in products that finish the surface pure white. For this reason, it is preferable to laminate and manufacture the layer not containing carbon fiber as the front side, that is, the side facing the room in the case of ceiling construction, and the layer containing carbon fiber as the back side. As described above, as described above, the layer containing carbon fiber may be made first, or the layer containing no carbon fiber may be made first, and the layer containing carbon fiber and the layer not containing carbon fiber may be used. It is preferable to continuously produce and laminate them. The layer containing carbon fiber is preferably manufactured as the back side for design. Although the thickness of each layer is not particularly limited, it is preferable in terms of dispersibility of the carbon fiber that the layer not containing carbon fiber is usually thin and the layer containing carbon fiber is thick.
[0030]
Since the carbon fiber is separated from the state in which the fibers are converged, if the carbon fiber is mixed in water simultaneously with other compounding components and stirred, the dispersion of the carbon fiber becomes insufficient and good radio wave absorption characteristics cannot be obtained. As a result of diligent investigations on the problems, the inventors have introduced 1 to 30 mm carbon fiber in water at a rate of 0.5 to 2 wt%, and the rotation speed is 0 with a mixer of 100 to 400 rpm. It was found that a good dispersion state was obtained by stirring for 5 to 3 minutes. By using this in combination with other blending components, it is possible to obtain a non-combustible sound-absorbing radio wave-absorbing ceiling board that exhibits suitable radio wave absorption performance.
[0031]
In the component constitution of the present invention, inorganic fillers such as aluminum hydroxide, pearlite, and shirasu balloon can be blended for the purpose of nonflammability and density adjustment. The mixing ratio of aluminum hydroxide is preferably 50 wt% or less in the form of replacing rock wool. If it exceeds 50 wt%, the drainage time becomes longer, the productivity at the time of molding becomes worse, and the strength is lowered. Perlite and shirasu balloons are also used in the form of replacing rock wool, and preferably 30 wt% or less from the relationship between density and strength.
[0032]
In the case where a metal foil is bonded to the back surface of the nonflammable sound absorbing and radio wave absorbing ceiling plate, in addition to the performance as a nonflammable sound absorbing and radio wave absorbing ceiling plate, the performance of shielding radio waves can be imparted. In addition, the radio wave absorption performance is effective in combination with the radio wave shielding performance because the radio wave absorptivity caused by the resonance phenomenon of the metal foil reflected radio wave is added and is effective. It is also a good idea from the viewpoint of workability. In addition, with the back surface said by this-application specification, let the indoor side of the ceiling board after construction be a surface, and let a ceiling back side be a back surface. When bonding metal foil such as aluminum foil and steel foil to the ceiling plate, it is bonded via an adhesive such as acrylic resin, vinyl acetate resin, ethylene resin, vinyl resin, urethane resin, epoxy resin, synthetic rubber, etc. I do. The metal foil is bonded to the back side of the ceiling board. The thickness of the metal foil is set to 5 to 200 μm in consideration of surface protection and panel workability, and more preferably, a soft metal foil of 50 to 100 μm is selected.
[0033]
On the other hand, the results of studying more effective radio wave absorption conditions regarding the resonance phenomenon will be described in detail below.
A radio wave reflector such as an aluminum foil is provided on the back of the radio wave absorber, and the phase of the incident wave and the reflected wave is reversed by the dielectric permeability effect of the radio wave absorber. In the case of a method for obtaining performance, the radio wave reflection layer is an essential component. However, the radio wave absorber provided with these radio wave reflectors on the back surface has a structure in which a metal foil such as an aluminum foil is laminated, which increases the cost. Moreover, since metal bodies, such as aluminum, may corrode, when adhering a radio wave absorber to another structure, the adhesion failure with a resin adhesive may occur.
[0034]
Also, when throwing away the gypsum board and decorating the rock wool board, if you want the ceiling board to have radio wave absorption performance, one way is to add ferrite or conductive fiber inside the gypsum board, There is a method in which an electromagnetic wave absorbing gypsum board with aluminum foil is used, and a non-combustible absorbent ceiling board is applied to the lower surface using a tucker and an adhesive.
As a second method, the composition of the gypsum board is a general gypsum board composition, an aluminum foil is laminated on the lower surface of the gypsum board, and an incombustible sound absorbing radio wave absorbing decorative ceiling board blended with ferrite and conductive fibers is used as a tacker and an adhesive. There is a method of construction using. The third method is to throw away the ordinary gypsum board that does not absorb radio waves, and paste metal foil such as aluminum foil on the back of the non-combustible sound-absorbing radio wave absorbing decorative ceiling board containing ferrite and conductive fibers. A method may be considered in which the paste is attached to a gypsum board using an adhesive and a tucker.
[0035]
However, in the first method, the cost of the gypsum board becomes high due to bonding of metal foil such as aluminum foil. In the second method, in addition to the high cost of the gypsum board, a metal foil such as an aluminum foil is interposed between the gypsum board and the decorative ceiling board. The force is reduced and the decorative ceiling board is easy to peel off. In the third method, there is no increase in the cost of the gypsum board, but in addition to the high cost of the radio wave absorption decorative ceiling board, the adhesive to the decorative ceiling board is caused by the corrosion of the metal foil for the same reason as the second method. The force is reduced and the decorative ceiling board is easy to peel off. Metal ceilings are used for so-called system ceilings, such as direct installation methods that do not throw away plasterboards, methods that place decorative ceiling plates on ceiling fittings (lay-in method), and methods in which fittings are inserted into the edge of decorative ceiling plates and supported. It goes without saying that the radio wave absorption gypsum board of can not be used. Incombustible sound-absorbing radio wave-absorbing ceiling panels with metal foil on the back of decorative ceiling panels are expensive and have not yet been widely used.
[0036]
Based on the above situation, we examined various results of the radio wave absorption performance test. As a result of setting the radio wave absorption test, a metal plate was installed on the back side of the ceiling plate of the test specimen, so absorption due to so-called resonance from radio wave reflection. It has been found that the addition of the characteristics is also a cause of the preferable absorption performance. Therefore, carbon fiber exhibits good radio wave absorption performance with a blending amount of 0.02 wt% or more in a conventional radio wave absorption test, but 0.02 wt% when there is no radio wave reflector such as a metal foil on the back surface. In the case of a blending amount from% to less than 0.08 wt%, it was found that the radio wave absorption performance was lowered and did not reach a more desirable preferable absorption performance.
[0037]
On the other hand, from 0.4 wt% to 1.5 wt% shows a certain amount of radio wave absorption performance, but as the blending amount is increased from 0.4 wt%, the radio wave reflection characteristics become stronger, resulting in a demerit that the absorption performance is reduced. There is. On the other hand, if it exceeds 1.5 wt%, the radio wave reflectivity of the panel becomes too strong, and the radio wave absorption performance is significantly reduced. Therefore, by setting the blending ratio of the carbon fiber having a fiber length of 1 to 30 mm in the range of 0.08 to 0.4 wt%, it is desirable even if the metal foil is not bonded to the back surface of the non-combustible sound absorbing radio wave absorbing ceiling plate. It was found that the preferred radio wave absorption can be performed.
[0038]
Furthermore, as described above, when the carbon fiber content is low, it is difficult to obtain a desired suitable absorption performance without a radio wave reflector such as a metal foil on the back surface. 100 to 3000 g / m of organic paint containing more carbon fiber ² It was found that the desired and suitable radio wave absorption performance can be obtained by coating in the amount of. It is presumed that when the carbon fiber layers having different blending ratios are adjacent to each other, the resonance effect is increased between the two layers, and the absorption characteristics are improved.
Furthermore, since the amount of carbon fiber on the front side is small, it is advantageous in terms of aesthetics.
[0039]
The carbon fiber content on the front side is preferably 0.08 wt% or less, more preferably 0.04 to 0.08 wt%, and the carbon fiber content in the organic paint on the back side is preferably 1.0 wt%. As mentioned above, More preferably, it is 1.0-15.0 wt%.
[0040]
As the organic paint of the present invention, a vinyl acetate emulsion paint is preferably used, and examples thereof include a polyvinyl acetate emulsion paint (PC coat), a polyvinyl alcohol emulsion paint, and a polyvinyl acetal emulsion paint.
The carbon fiber blended in the organic paint can include the same carbon fiber as described above. The fiber length is not particularly limited, but is preferably 0.1 to 30 mm, and easy to uniformly disperse and mix. From the point of property, 0.5-2 mm is especially preferable.
[0041]
【Example】
Examples 1 to 11 and Comparative Examples 1 to 2 together with Tables 1 and 2 and Examples 12 to 19, Comparative Example 3 and Non-combustible sound absorbing and radio wave absorbing ceiling panels of the present invention are shown below. Reference Examples 1 and 2 will be described together with Tables 3 and 4, and Example 20 will be described together with Table 5.
[0042]
<Example 1>
SiO ₂ 41wt%, CaO36wt%, MgO6wt%, Al ₂ O _Three 12wt%, other Na ₂ O, K ₂ 89.6 wt% of steel slag rock wool with a fiber length of 100 to 500 μm composed of 5 wt% of trace components such as O, 1 wt% of beaten pulp dispersed in water and beaten with a refiner, 5.5 wt% of starch, Dispersed and defatted attapulgite 2.85 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (solid content base), aluminum sulfate 0.6 wt%, pre-treated in water at a rate of 1 wt%, 200 revolutions Stirring with a mixer at a rotation speed of 2 min / min, carbon fiber with a fiber length of 4 mm (Osaka Gas Co., Ltd .; Zyrus) was added and mixed with 0.25 wt% (based on solid content), and dispersed with a mixer. To prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of this original plate is cut to obtain a plate thickness of 12 mm and a bulk density of 0.4 g / cm. ^Three Panel A of the ceiling board for interior was obtained. Table 1 shows the strength, fire resistance, thermal resistance, sound absorption rate, radio wave shielding performance, radio wave absorption performance, and the like of panel A.
[0043]
<Example 2>
The carbon fiber blending ratio of Example 1 was 0.025 wt%, the rock wool blending ratio was 89.825 wt%. The performance of panel B is also shown in Table 1.
[0044]
<Example 3>
The carbon fiber blending ratio of Example 1 was 0.33 wt%, the rock wool blending ratio was 89.52 wt%, and the bulk density was 0.3 g / cm under the same setting conditions as in Example 1. ^Three As a result, panel C for interior ceiling board was obtained. The performance and the like of panel C are also shown in Table 1.
[0045]
<Example 4>
Panel D of the interior ceiling board was obtained under the same setting conditions as in Example 1 except that the blending ratio of carbon fiber of Example 1 was 0.3 wt%, the blending ratio of rock wool was 89.55 wt%. Table 1 also shows the performance and the like of a panel D having a plate thickness of 9 mm whose surface is cut.
[0046]
<Example 5>
Panel E for interior ceiling boards was obtained under the same setting conditions as in Example 1 except that the blending ratio of carbon fiber of Example 1 was 0.15 wt%, the blending ratio of rock wool was 89.7 wt%. Table 1 also shows the performance and the like of a panel E having a plate thickness of 15 mm whose surface is cut.
[0047]
<Example 6>
The carbon fiber blending ratio of Example 1 is 0.22 wt%, the rock wool blending ratio is 89.63 wt%, and the bulk density is 0.5 g / cm under the same setting conditions as in Example 1. ^Three The panel F for the ceiling board for interior was manufactured as follows. The performance of the panel F is also shown in Table 1.
[0048]
<Example 7>
The length of the carbon fiber of Example 1 is 1 mm, the blending ratio is 0.4 wt%, the blending ratio of rock wool is 89.45 wt%, and the other is the same as in Example 1, and the panel G of the ceiling board for interior use Manufactured. The performance of the panel G is also shown in Table 1.
[0049]
<Example 8>
The length of the carbon fiber of Example 1 is 12 mm, the blending ratio is 0.18 wt%, the blending ratio of rock wool is 89.67 wt%, and the other is the panel H of the ceiling board for interior use under the same setting conditions as in Example 1. Manufactured. The performance of the panel H is also shown in Table 2.
[0050]
<Example 9>
Panel I, an interior ceiling board with aluminum foil, was manufactured by bonding a soft aluminum foil with a thickness of 50 μm to the back of the panel obtained in Example 1 with an ethylene vinyl acetate adhesive. Table 2 also shows the performance and the like of the panel I attached with aluminum foil.
[0051]
<Example 10>
A mixture of 85.95% by weight of rock wool, 3% by weight of beating pulp, 7% by weight of polyvinyl alcohol, 3% by weight of attapulgite, 0.2% by weight of 15% strength polyacrylamide aqueous solution (based on solid content), and 0.6% by weight of aluminum sulfate 0.25 wt% (solid) of carbon fiber having a fiber length of 4 mm (manufactured by Osaka Gas Co., Ltd .; Zyrus) was added to water at a rate of 1 wt% and stirred with a mixer at a rotation speed of 200 rpm. Minute basis) and dispersing with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of the original plate was cut to obtain a panel J of an interior ceiling plate having a thickness of 12 mm and having sufficient strength as an interior ceiling plate. Table 2 shows the performance, such as strength, fire resistance, thermal resistance, sound absorption rate, radio wave shielding performance, and radio wave absorption performance of panel J.
[0052]
<Example 11>
Rock wool 60.95 wt%, beaten pulp 3 wt%, polyvinyl alcohol 7 wt%, attapulgite 3 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (solid content base), aluminum sulfate 0.6 wt%, aluminum hydroxide 25 wt% Carbon fiber with a fiber length of 4 mm (manufactured by Osaka Gas Co., Ltd .; Zyrus) was added to the resulting mixture as a pretreatment at a rate of 1 wt% in water and stirred with a mixer for 2 minutes at a rotation speed of 200 rpm. 0.25 wt% (based on solid content) is added and dispersed with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%.
The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of the original plate is cut to have a sufficient strength as an interior ceiling plate, a plate thickness of 12 mm and a bulk density of 0.45 g / cm. ^Three Panel K for interior ceiling board was obtained. Table 2 shows the performance, such as strength, fire resistance, thermal resistance, sound absorption rate, radio wave shielding performance, and radio wave absorption performance of the panel K.
[0053]
[Comparative Example 1]
Mixing of rock wool 90.25 wt%, beaten pulp 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (solid content base), aluminum sulfate 0.6 wt% Disperse with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry was made with a long net making machine, dehydrated and dried to obtain an interior ceiling panel L having a thickness of 12 mm. Table 2 shows the performance, such as strength, fire resistance, thermal resistance, sound absorption rate, radio wave shielding performance, and radio wave absorption performance of the panel L.
[0054]
[Comparative Example 2]
Rock wool 88.35 wt%, beaten pulp 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% strength polyacrylamide aqueous solution 0.2 wt% (solid content base), aluminum sulfate 0.6 wt%, fiber length 4 mm A mixture of 1.5 wt% of carbon fiber (Osaka Gas Co., Ltd .; Zyrus) is dispersed with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of the original plate was cut to obtain an interior ceiling panel M having a thickness of 12 mm and having sufficient strength as an interior ceiling plate. Table 2 shows the performance of the panel M, such as strength, fire resistance, thermal resistance, sound absorption rate, radio wave shielding performance, and radio wave absorption performance.
[0055]
[Table 1]

[0056]
[Table 2]

[0057]
<Evaluation measurement method of Table 1 and Table 2>
Bending strength: According to JIS A 1408 (No. 5 specimen) method.
Thermal resistance: According to JIS A 1420 method.
Fire prevention performance: According to JIS A 1321 method.
Sound absorption rate: According to JIS A 1409 (reverberation room) method.
Radio wave shielding performance: A test specimen having a thickness of 9 to 15 mm and a vertical and horizontal length of 400 mm × 400 mm for each test is installed between the radio wave transmitting antenna and the receiving antenna, and the transmission level is measured by the time domain method. The transmission coefficient was calculated by comparing with the transmission level when the test specimen was not installed, and was defined as the radio wave shielding performance.
Radio wave absorption performance: In accordance with "Radio wave absorber performance evaluation and measurement method" that is being studied by the Architectural Institute of Japan, on the back side of a test body having a thickness of 9 to 15 mm and a length and width of 400 mm x 400 mm for each test, Using a metal plate with a length and width of 400 mm x 400 mm bonded together, the reflection coefficient is measured by the free space time domain method. The reflection coefficient was calculated by comparing with the reflection level of only the metal plate, and used as the radio wave absorption performance.
[0058]
<< Comparison between Examples and Comparative Examples in Tables 1 and 2 >>
1. About bending strength, all have shown the aptitude value as an interior ceiling board.
2. As for thermal resistance, all show sufficient heat insulation, and there is no significant difference.
3. About fireproofness, Examples 1-9 and Example 11, and Comparative Examples 1-2 are nonflammable, Example 10 is semi-incombustible and passes.
4). As for the sound absorption rate, in Examples 1 to 11 and Comparative Examples 1 and 2, all show appropriate sound absorption rates, and there is no significant difference.
5). The radio wave shielding performance shows a shielding performance of 2 to 5.5 dB in Examples 1 to 8 and Examples 10 to 11 and Comparative Example 2, but has sufficient performance as a general radio wave shielding material. Not. In Example 9, the shielding performance of 31 dB or more is shown, which satisfies 30 dB or more, which is sufficient performance as a general radio wave shielding material. In Comparative Example 1, radio wave shielding performance is not shown.
6). Regarding the electromagnetic wave absorption performance, 6 to 15 dB at 2.45 GHz and 6 to 12 dB at 5.1 GHz in Examples 1 to 11, and in the 2.4 GHz band and 5 GHz band used for the wireless LAN system. In the wireless communication such as the above, it has sufficient absorption performance as a countermeasure against communication failure. On the other hand, in the case of the comparative example 1 which does not mix | blend the carbon fiber as an electroconductive substance, absorption performance is not acquired and the said conditions are not satisfy | filled. Moreover, in the comparative example 2, since carbon fiber is highly blended, it is affected by radio wave reflection and does not show sufficient absorption performance.
[0059]
About Examples 1-11, and Comparative Examples 1-2, according to the "radio wave absorber performance evaluation measurement method" which has been examined by the Architectural Institute of Japan, radio wave absorption is performed in a state in which a specimen is bonded to a metal plate. Measuring. Therefore, the radio wave absorption performance is measured in a state where the radio wave absorption performance due to resonance and the radio wave absorption performance due to internal loss of the test specimen itself are mixed, and the test specimen itself in the measurement of the radio wave absorber that does not have a radio wave reflector on the back surface It was found that it was difficult to measure the radio wave absorption performance due to internal loss. As a result of intensive studies in order to measure the internal absorption characteristics of the test specimen more accurately and to express the difference from the absorption performance due to the resonance phenomenon more clearly, the present inventor It is found that the generation of resonance phenomenon can be prevented by providing a space, and a 100 mm space is provided in front of a 400 mm × 400 mm metal plate so that the test body is installed so that the metal plate and the test body are not integrated. The reflection coefficient was measured by the free space time domain method with no resonance phenomenon. The reflection coefficient was calculated by comparing with the reflection level of only the metal plate, and used as the radio wave absorption performance. Subsequently, the reflection coefficient was measured by a free space timed domain-in method for a structure in which an aluminum foil was stretched on the back surface of the test specimen and a resonance phenomenon occurred. By this method, more effective radio wave absorption can be measured.
[0060]
Hereinafter, regarding the incombustible sound absorbing radio wave absorptive ceiling plate of the present invention, including the comparison between the condition that does not cause the resonance phenomenon and the condition that causes the resonance phenomenon with the aluminum foil pasted on the back surface, Examples 12 to 19, below. This will be described with reference to Comparative Example 3 and Reference Examples 1-2.
[0061]
<Example 12>
SiO ₂ 41wt%, CaO36wt%, MgO6wt%, Al ₂ O _Three 12wt%, other Na ₂ O, K ₂ 89.75 wt% of steel slag rock wool with a fiber length of 100 to 500 μm composed of a composition of 5 wt% of trace components such as O, 1 wt% of beaten pulp dispersed in water and beaten with a refiner, 5.5 wt% starch, Dispersed and defatted attapulgite 2.85 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (solid content base), aluminum sulfate 0.6 wt%, pre-treated in water at a rate of 1 wt%, 200 revolutions Stirring with a mixer for 2 minutes at a rotation speed of / min. Carbon fiber with a fiber length of 4 mm (Osaka Gas Co., Ltd .; Zyrus) was added and mixed with 0.1 wt% (solid content base), and dispersed with a mixer. To prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of this original plate is cut to obtain a plate thickness of 12 mm and a bulk density of 0.4 g / cm. ^Three Panel N for the interior ceiling board was obtained. Table 3 shows the strength, fire resistance, thermal conductivity, sound absorption coefficient, radio wave shielding performance, radio wave absorption performance, and the like of panel N. As shown in Table 3, Example 12 has good radio wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.
[0062]
<Example 13>
The carbon fiber blending ratio of Example 12 was 0.40 wt%, the rock wool blending ratio was 89.45 wt%, and other components were obtained under the same setting conditions as in Example 12 to obtain an interior ceiling panel O. The performance of the panel O is also shown in Table 3. As shown in Table 3, Example 13 has good radio wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.
[0063]
<Example 14>
The carbon fiber blending ratio of Example 12 was 0.3 wt%, the rock wool blending ratio was 89.55 wt%, and the others were the same setting conditions as in Example 12 to obtain an interior ceiling panel P. Table 3 also shows the performance and the like of a panel P having a plate thickness of 9 mm whose surface is cut. As shown in Table 3, Example 14 has good radio wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.
[0064]
<Example 15>
Panel Q of interior ceiling board was obtained under the same setting conditions as in Example 1 except that the blending ratio of carbon fiber of Example 12 was 0.15 wt%, the blending ratio of rock wool was 89.7 wt%. Table 3 also shows the performance and the like of a panel Q having a plate thickness of 15 mm whose surface is cut. As shown in Table 3, Example 15 has good radio wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.
[0065]
<Example 16>
The carbon fiber concentration of Example 12 was 0.3 wt%, the blending ratio of rock wool was 89.55 wt%, and the bulk density was 0.5 g / cm under the same setting conditions as in Example 12. ^Three The panel R of the ceiling board for interior was obtained so that it might become. The performance of the panel R is also shown in Table 3. As shown in Table 3, Example 16 has good radio wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.
[0066]
<Example 17>
The carbon fiber length of Example 12 is 12 mm, the concentration is 0.18 wt%, the blending ratio of rock wool is 89.67 wt%, and the other is the same as in Example 12, and an interior ceiling panel S is obtained. It was. The performance of the panel S is also shown in Table 3. As shown in Table 3, Example 17 has a good radio wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.
[0067]
<Example 18>
Rock wool 86.1 wt%, gel 3 wt%, polyvinyl alcohol 7 wt%, attapulgite 3 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (solid content base), aluminum sulfate 0.6 wt%, fiber length 4 mm carbon fiber ( A mixture of 0.1 wt% (based on solid content) of Osaka Gas Co., Ltd. (Zyrus) is dispersed with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of the original plate was cut to obtain an interior ceiling panel T having sufficient strength as an interior ceiling plate. Table 4 summarizes the performance of the panel T, such as strength, fire resistance, thermal conductivity, sound absorption rate, radio wave shielding performance, and radio wave absorption performance. As shown in Table 4, Example 18 has good radio wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.
[0068]
<Example 19>
Rock wool 61.1 wt%, gel 3 wt%, polyvinyl alcohol 7 wt%, attapulgite 3 wt%, 15% strength polyacrylamide aqueous solution 0.2 wt% (solid content base), aluminum sulfate 0.6 wt%, aluminum hydroxide 25 wt%, fiber A mixture of 0.1 wt% (solid content base) of carbon fiber having a length of 4 mm (Osaka Gas Co., Ltd .; Zyrus) is dispersed with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of the original plate was cut to obtain a panel U of an interior ceiling plate having sufficient strength as an interior ceiling plate. Table 4 summarizes the performance of the panel U, such as strength, fire resistance, thermal conductivity, sound absorption rate, radio wave shielding performance, and radio wave absorption performance. As shown in Table 4, Example 19 has good radio wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.
[0069]
[Comparative Example 3]
Mixer consisting of 89.85wt% rock wool, 1wt% gel, 5.5wt% starch, 2.85wt% attapulgite, 0.2wt% 15% strength polyacrylamide aqueous solution (solid content base), 0.6wt% aluminum sulfate To prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of the original plate was cut to obtain a panel V of an interior ceiling plate having sufficient strength as an interior ceiling plate. Table 4 summarizes the performance of panel V, such as strength, fire resistance, thermal conductivity, sound absorption rate, radio wave shielding performance, and radio wave absorption performance. As shown in Table 4, Comparative Example 3 does not have radio wave absorption performance when the aluminum foil is pasted on the back surface or when the aluminum foil on the back surface is not pasted.
[0070]
[Reference Example 1]
Rock wool 89.80 wt%, gel 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (based on solid content), aluminum sulfate 0.6 wt%, fiber length 4 mm A mixture of 0.05 wt% carbon fiber (Osaka Gas Co., Ltd .; Zyrus) is dispersed with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Further, the surface of the original plate was cut to obtain an interior ceiling panel W having sufficient strength as an interior ceiling plate. Table 4 summarizes the performance of panel W such as strength, fire resistance, thermal conductivity, sound absorption rate, radio wave shielding performance, and radio wave absorption performance. As shown in Table 4, in Reference Example 1, the desired radio wave absorption performance was obtained when the aluminum foil was attached to the back surface, but sufficient radio wave absorption performance was not obtained when the back surface aluminum foil was not applied.
[0071]
[Reference Example 2]
Rock wool 89.25 wt%, gel 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (solid content base), aluminum sulfate 0.6 wt%, fiber length 4 mm A mixture composed of 0.6 wt% of carbon fiber (Osaka Gas Co., Ltd .; Zyrus) is dispersed with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made with a long net making machine, dehydrated and dried to produce an original plate. Furthermore, the surface of the original plate was cut to obtain a panel X of an interior ceiling plate having sufficient strength as an interior ceiling plate. Table 4 summarizes the performance of panel X, such as strength, fire resistance, thermal conductivity, sound absorption rate, radio wave shielding performance, radio wave absorption performance, and the like. As shown in Table 4, in Reference Example 2, when the aluminum foil is pasted on the back surface and when the back surface aluminum foil is not pasted, sufficient radio wave absorption performance of 6 dB or more cannot be obtained.
[0072]
[Table 3]

[0073]
[Table 4]

[0074]
<Evaluation measurement method of Table 3 and Table 4>
Bending strength: According to JIS A 1408 (No. 5 specimen) method.
Thermal resistance: According to JIS A 1420 method.
Fire prevention performance: According to JIS A 1321 method.
Sound absorption rate: According to JIS A 1409 (reverberation room) method.
Radio wave shielding performance: A test specimen having a thickness of 9 to 15 mm and a vertical and horizontal length of 400 mm × 400 mm for each test is installed between the radio wave transmitting antenna and the receiving antenna, and the transmission level is measured by the time domain method. The transmission coefficient was calculated by comparing with the transmission level when the test specimen was not installed, and was defined as the radio wave shielding performance.
Radio wave absorption performance: In order to prevent resonance phenomenon from reflected radio waves and measure only radio wave absorption performance due to internal loss of the specimen itself, a space of 100 mm is provided in front of a metal plate 400 mm x 400 mm in length and width. A test specimen having a thickness of 9 to 15 mm for each test and a vertical and horizontal length of 400 mm × 400 mm was installed, and the reflection coefficient was measured by a free space time domain method in a state where a resonance phenomenon due to radio wave reflection did not occur. The reflection coefficient was calculated by comparing with the reflection level of only the metal plate, and used as the radio wave absorption performance. Subsequently, the reflection coefficient of the test body having a configuration in which an aluminum foil was pasted on the back surface of the test body and in which a resonance phenomenon due to radio wave reflection occurred was measured by the free space time domain method.
[0075]
<< Comparison between Examples and Comparative Examples in Tables 3 and 4 >>
1. About bending strength, all have shown the aptitude value as an interior ceiling board.
2. As for thermal resistance, all show sufficient heat insulation, and there is no significant difference.
3. About fireproofness, Examples 12-17 and Example 19, and the comparative example 3 and the reference examples 1-2 are nonflammable, Example 18 is non-flammable and passes.
4). As for the sound absorption rate, Examples 12 to 19, Comparative Example 3 and Reference Examples 1 and 2 all show appropriate sound absorption rates, and there is no significant difference.
5). The radio wave shielding performance shows a shielding performance of 2 to 6.8 dB in Examples 12 to 19 and Reference Examples 1 to 2 under the condition without an aluminum foil, but sufficient performance as a general radio wave shielding material is I don't have it. In Comparative Example 3, the radio wave shielding performance is hardly shown.
6). As for the radio wave absorption performance, in Examples 12 to 19, both when the aluminum foil is integrated on the back surface and when the aluminum foil is not integrated on the back surface, it is 6 to 9 dB at 5.45 GHz and 5.1 GHz. 6 to 9 dB is shown, and in wireless communication in the 2.4 GHz band and 5 GHz band used for wireless LAN systems, etc., both satisfy 6 dB or more, which is sufficient absorption performance as a countermeasure against communication failures. ing. Therefore, the conditions for blending the carbon fibers of Examples 12 to 19 indicate that good radio wave absorption performance can be obtained even when the aluminum foil is not integrated on the back surface. On the other hand, in the case of the comparative example 3 which does not mix | blend the carbon fiber as an electroconductive substance, absorption performance is not acquired. In Reference Example 1, carbon fiber is low in composition, so when aluminum foil is laminated on the back side, the desired radio wave absorption performance is exhibited by the addition of radio wave loss due to resonance phenomenon, but the aluminum foil is not laminated on the back side. Does not show sufficient absorption performance, and in Reference Example 2, since carbon fiber is highly blended, even when aluminum foil is not laminated on the back surface, it is affected by radio wave reflection and does not show sufficient absorption performance.
[0076]
Example 20
A vinyl acetate emulsion paint (polyvinyl acetate) containing various pitches of pitch-based carbon fibers having a fiber length of 0.7 mm, respectively, on the ceiling plate in which only the carbon fiber content in the ceiling plate described in Reference Example 1 is changed. 625 g / m) ² Each ceiling board was obtained by carrying out roller coat application in the quantity of. Table 5 shows the blending amounts of carbon fibers on the front and back surfaces (in the PC coat) of each ceiling panel and their radio wave absorption performance.
The radio wave absorption performance was measured by the same method as in Examples 12-19.
[0077]
[Table 5]

[0078]
From the results in Table 5, if the amount of carbon fiber on the surface (especially referred to as “CF1”) is 0.10 wt% or more, very good radio wave absorption performance can be obtained without adding carbon fiber to the PC coat. However, when the CF1 content is 0.08 wt% or less, a sufficient radio wave absorption performance cannot be obtained with a structure in which no aluminum foil is applied. On the other hand, even when CF1 is in a low blending amount, by applying a PC coat that blends a larger amount of carbon fiber (the blending amount in the PC coat is particularly referred to as “CF2”) to the back surface. It can be seen that the radio wave absorption performance is significantly improved.
[0079]
In particular, by devising the blending amount of both, an absorption performance of 6 dB or more, which is an absorption performance suitable for wireless communication applications (wireless LAN), can be obtained. In particular, when the carbon fiber blending amount (CF1) of the surface side ceiling board is 0.04 wt% to 0.08 wt% and the blending amount (CF2) in the PC coat is 1.0 wt% to 15.0 wt%, the above preferable absorption performance Is obtained.
[0080]
【The invention's effect】
As described above, the non-combustible sound absorbing radio wave absorbing ceiling board of the present invention is lightweight and has a fireproof performance from semi-incombustible to non-combustible, and has both sound absorbing property, heat insulating property, and radio wave absorbing property, and is low in cost and sufficient. Since it has bending strength, it has an effect as a non-combustible sound absorbing radio wave absorbing ceiling board that can suitably meet various functional needs as a building structure and building members.
[0081]
In addition, in the non-combustible sound-absorbing and radio-absorbing ceiling board, a design effect is added to the indoor side surface after construction by adopting a laminated structure of a layer not including carbon fiber and a two-layer structure including carbon fiber. An interior ceiling board can be obtained.
[0082]
Furthermore, in the case of adopting a metal foil-clad ceiling board that absorbs non-combustible sound-absorbing radio waves, it has the effect of adding and improving radio wave shielding in addition to the radio wave absorption effect that additionally improves radio wave absorption due to the resonance phenomenon of reflected radio waves.
[0083]
The incombustible sound-absorbing radio wave absorbing ceiling plate of the present invention has a radio wave absorptivity due to a resonance phenomenon from a reflected radio wave by setting the mixing ratio of the carbon fiber having a fiber length of 1 to 30 mm to 0.08 to 0.4 wt%. Even without the addition, excellent radio wave absorption performance can be obtained, and in particular, there is an effect that it is possible to obtain suitable radio wave absorption performance particularly for radio communication applications (wireless LAN), particularly radio wave absorption performance of 6 dB or more.
[0084]
Furthermore, the blending ratio of the carbon fiber having a fiber length of 1 to 30 mm is set to 0.04 to 0.08 wt%, and an organic paint for blending the carbon fiber in a larger amount than the blending amount of the carbon fiber is applied to the back surface thereof. Therefore, excellent radio wave absorption performance can be obtained, and particularly suitable absorption performance for wireless communication can be obtained.

Claims (3)

Rock wool 67 to 92 wt%, beaten pulp 0.5 to 8 wt%, organic resin binder 2 to 13 wt%, flocculant 0.15 to 1 wt%, natural mineral fiber 0.5 to 10 wt% , and pretreatment It is obtained by wet-making a water-dispersed slurry of a mixture containing 0.02 to 1 wt% of carbon fibers having a fiber length of 1 to 30 mm, which is stirred by introducing into water at a ratio of 0.5 to 2 wt% with respect to water A radio wave absorptive ceiling board for indoor wireless communication obtained by attaching a metal foil to the back surface of a board having a thickness of 1 to 30 mm.   Carbon fiber having a fiber length of 1 to 30 mm is introduced into water at a rate of 0.5 to 2 wt% as a pretreatment, and the mixture is stirred for 0.5 to 3 minutes with a mixer having a rotation speed of 100 to 400 rpm,
  Rock wool 67 to 92 wt%, beaten pulp 0.5 to 8 wt%, organic resin binder 2 to 13 wt%, flocculant 0.15 to 1 wt%, natural mineral fiber 0.5 to 10 wt% and the above pretreatment An aqueous dispersion slurry of a mixture containing 0.02 to 1 wt% of carbon fiber is obtained,
  Wet-making the water-dispersed slurry,
  The wet-made water-dispersed slurry is dehydrated and dried to obtain an original plate,
  Cutting the original plate to obtain a panel; and
  A method for manufacturing a radio wave absorbing ceiling board for indoor wireless communication, wherein a metal foil is attached to the panel. Using ceiling plate of claim 1 Symbol mounting method prevents the indoor wireless communication failure.