JP3790694B2

JP3790694B2 - Glass fiber molded article and molding method thereof

Info

Publication number: JP3790694B2
Application number: JP2001311137A
Authority: JP
Inventors: 和男小寺
Original assignee: NIHON GLASS FIBER INDUSTRIAL CO., LTD.
Current assignee: NIHON GLASS FIBER INDUSTRIAL CO., LTD.
Priority date: 2001-10-09
Filing date: 2001-10-09
Publication date: 2006-06-28
Anticipated expiration: 2021-10-09
Also published as: JP2003113565A

Description

【０００１】
【発明の属する技術分野】
本発明は、ガラス繊維成形品及びその成形方法に関するものである。
【０００２】
【従来の技術】
ガラス繊維からマット、ボード、ペーパー等の成形品を成形する方法としては、下記のものがある。
▲１▼ フェルト成形：ガラス短繊維をバインダにより接着して結合し、フェルトマット状にまとめる方法である。
▲２▼ ニードリング：ガラス長繊維をニードルパンチ加工により絡み合わせて結合し、やや圧縮されたマット状に成形する方法である。その表面をバインダで被覆する場合もある。
▲３▼ 抄造：ガラス繊維をバインダ添加水に入れてスラリを形成し、このスラリを紙を抄くように掬い上げてから乾燥させて、ガラス繊維間をバインダにより接着して結合する方法である。
上記▲１▼〜▲３▼に使用される各バインダとしては、澱粉系、シリコン系、ゴム系等の有機バインダが一般的であり、有機バインダにシリカ系等の無機バインダを混合する場合もある。
【０００３】
ガラス繊維材を無機バインダで固めたガラス繊維成形体を使用する例は、この無機バインダで固めたガラス繊維成形体に付着させた吸着剤と、これらを密閉する少なくとも１つの金属箔を有するラミネートフィルムとを具備する断熱パネルがある（特開昭６３−１８７０８４号公報）。
【０００４】
また、ガラス繊維同士を接着する効果を持つ方法として、無機質繊維同士を酸処理により、該繊維の溶出した成分で各接触点を結着させた真空断熱材がある（特開平７−１６７３７６号公報）。
【０００５】
【発明が解決しようとする課題】
上記のフェルト成形、ニードリング及び抄造には、後出の表１にまとめた通りの利点と欠点とがあり、それぞれの利点を生かした用途に適用されている。しかし、成形品が高温使用に適し、かつ、種々の形状への成形の容易性があり、成形品の強度も高くなるといった成形方法はなかった。すなわち、フェルト成形及び抄造は有機バインダを必須とする。そのため、成形品の高温使用時に有機バインダの分解により煙が発生するとか、有機バインダによる結合力が失われて耐熱性がなくなるとか、このようなガラス繊維成形体を真空包装して用いる場合には、有機バインダが気化することにより真空度が低下し断熱性能が劣化する問題があり、高温使用には適さなかった。一方、ニードリングはバインダを必須としないため、バインダを被覆をしない限りこのような問題はないが、単純板状のマットしか成形することかできないとか、飛び飛びのニードリング点による結合なので成形品の強度を高めにくいとかという問題があった。
【０００６】
無機バインダを使った場合は、無機バインダが粉末化し、被覆材を封止する部分に飛散し、封止が不完全となって真空度が落ち、断熱性能を高く維持するために必要な完全な密閉を阻害する危険性が生じるという問題があった。
また、無機バインダにはシリカゾル、セメント系などがあるが、有機バインダと比較して、耐圧性に劣るという問題があった。
【０００７】
さらに、無機バインダのみの結着力では、０．１ＭＰａ（１．０２ｋｇ／ｃｍ^２）加圧での圧縮率を１０％以下にするには、嵩密度の増加を要し、熱伝導率や真空脱気性を低下させてしまう。また、圧縮率が１０％を越えると、コア材として断熱容器や袋に入れ真空排気した際に、真空力で断熱容器や袋が顕著に凹むという問題点を有する。
【０００８】
また、酸処理によるガラス繊維同士の結着方法は、結着部に酸の成分が残りやすく、ステンレス等の被覆材の腐食劣化を伴いやすく、環境が汚染されるという問題があった。
【０００９】
本発明の目的は、上記課題を解決し、成形品が高温使用に適し、繊維の持つ柔軟性を維持し、比較的容易にかつ安価に複雑形状のガラス繊維成形品及びその成形方法を、提供することにある。
【００１０】
【課題を解決するための手段】
上記目的を達成するために、本発明のガラス繊維成形品は、ガラス繊維が該ガラス繊維に付着した無機バインダによる繊維間の固着を伴って所望の圧縮形状に圧縮成形されてから、該ガラス繊維と該無機バインダとの間及び該ガラス繊維同士の接触点が、ガラスの軟化点より低い温度で表面融着されてなることを特徴とする。
【００１１】
また、本発明のガラス繊維成形品の成形方法は、ガラス繊維に無機バインダを付着する付着工程と、該ガラス繊維を所望の圧縮形状に圧縮し、該ガラス繊維に付着した無機バインダが繊維間を固着することで圧縮形状を保持する圧縮成形工程と、該ガラス繊維を該ガラス繊維の軟化点より１０〜１００℃だけ低い温度に保持することにより、該ガラス繊維と該無機バインダとの間及び該ガラス繊維同士の接触点を融着させる融着工程と、前記ガラス繊維を冷却することにより前記融着を固化させる固化工程とを含むことを特徴とする。
【００１２】
ガラス繊維を構成するガラスの種類は、特に限定されないが、Ａガラス、Ｃガラス、Ｅガラス、Ｔガラス等を例示できる。また、ガラス繊維に、ガラス繊維以外の耐熱性無機繊維（アルミナ繊維、セラミック繊維、シリカ繊維、ロックウール等）又は耐熱性金属繊維（ステンレス鋼、クロム−ニッケル系合金、高ニッケル合金、高コバルト合金等の繊維）を混合することもできる。ガラス繊維の繊維径は、特に限定されないが、１〜３０μｍが好ましく、真空度にもよるが、細いほど熱伝導率が低くなり、断熱性能に優れる傾向がある。
【００１３】
無機バインダとしては、シリカゾル、アルミナゾル、チタニアゾル、ジルコニアゾル、水ガラス等を例示でき、これらを混合してもよく、あるいはセラミック粉体、低融点ガラスを添加してもよい。セラミック粉体を添加する場合、固体熱伝導率の低い粉体のチタニア、窒化珪素が好ましい。さらにこの場合は、空隙が小さくなり、気体熱伝導がほとんどなくなるため、真空断熱性能が向上する。一方、セラミック粉体を添加すると、物体の伝熱点が多くなり、粉体中を熱が伝わる固体熱伝導が大きくなるため、真空断熱性能が悪化する問題点がある。そのため、セラミック粉体を添加したガラス繊維成形品を真空断熱用コア材として使う場合は、その温度条件にて、相反する熱伝導が最大限に低減できる添加量に調整することが重要となる。
さらに、必要に応じて無機バインダの付着分散性と付着力を高めるため、有機バインダを添加してもよい。有機分は後工程の加熱処理で気化され、排除することができる。
【００１４】
付着工程は特に限定されないが、ガラス繊維をニードリングしてなるニードルマットを無機バインダに浸漬し、ローラにて絞る方法を例示できる。
圧縮成形工程は特に限定されないが、ガラス繊維を加熱した挟み板により圧縮する方法を例示できる。
【００１５】
融着工程は特に限定されないが、無機バインダで固着して圧縮成形されたガラス繊維を、挟み板よりはずして、加熱によりガラス繊維と無機バインダとの間及びガラス繊維同士の接触点を融着させる方法を例示できる。この際、ガラス繊維は無機バインダにて外熱より保護された形となっている。加熱条件は限定されないが、繊維の劣化を防止し、柔軟性を維持するため、軟化点より１０〜１００℃だけ低い温度でかつ短時間で融着処理することが好ましい。
【００１６】
前記温度を「軟化点より１０〜１００℃だけ低い温度」としたのは、この範囲の上限より高い温度ではガラス繊維が溶融しすぎて固まり状に収縮してしまうおそれがあり、この範囲の下限より低い温度ではガラス繊維の粘度が高すぎて融着しにくくなるからである。より好ましくは「軟化点より２０〜８０℃だけ低い温度」であり、さらに好ましくは「軟化点より３０〜６０℃だけ低い温度」である。
【００１７】
「軟化点より１０〜１００℃だけ低い温度」は、ガラス繊維を構成するガラスの粘度の観点からして「粘度が５×１０^７Ｐ〜１０^９Ｐとなる温度」と置き換えることもできる。粘度が５×１０^７Ｐより低くなるとガラス繊維が溶融しすぎて固まり状に収縮してしまうおそれがあり、粘度が１０^９Ｐより高くなると融着しにくくなるからである。より好ましくは「粘度が６×１０^７Ｐ〜８×１０^８Ｐとなる温度」であり、さらに好ましくは「粘度が７×１０^７Ｐ〜５×１０^８Ｐとなる温度」である。
【００１８】
ここで、ガラス繊維と無機バインダとの間及びガラス繊維同士の接触点を例にして融着するメカニズムを説明する。ガラス繊維は非晶質であるため、結晶質の物質が持っている融点は持たず、温度を上げていったとき、連続的に原始の移動とともに粘度が低下していき、液体へ移行してゆく。一般に、ガラスの軟化点とは粘度４．５×１０^７Ｐ（ｌｏｇη＝７．６５）のときの温度をいい、ガラスを成形できる下限温度とされている。本発明の成形方法は、このように連続的に変化するガラスの粘度を利用し、ガラスの粘度が４．５×１０^７Ｐよりやや低いときに、ガラス繊維と無機バインダとの間及びガラス繊維同士が互いの接触点で融着を起こす現象を利用し、繊維内部の熱劣化を生じない程度に表面融着すること、セラミックス粉体の焼結過程におけるネックを短時間で形成できる現象を利用している。実際、現象的には、セラミックスの焼結よりも、むしろ樹脂の成形の方が本メカニズムに近いと思われる。また、点接触の融着であるので、内部に閉じた気泡が取り残されることもない。
【００１９】
前記「軟化点より１０〜１００℃だけ低い温度」あるいは前記別範囲の各温度に保持する時間は、その範囲内における温度の高低によって異なり、温度が高い場合には短くし（例えば１〜２０分）、温度が低い場合には長くする（例えば１５〜５０分）。また、同時間は、圧縮形状・寸法によっても異なり、例えば厚さが大きくて熱が内部にまで伝わりにくい場合には長くする。
【００２０】
圧縮形状としては、特に限定されないが、板状（平板状のみならず、湾曲板状、波板状等も含む）、棒状、ブロック状等や箱状、管状等の複雑形状への成形を、さらに、表面に大きな凹凸を賦形する成形を例示できる。
【００２１】
ガラス繊維成形品は、特に限定されないが、多用されるのは嵩密度が２５０〜４８０ｋｇ／ｍ^３で、０．１ＭＰａ加圧にて圧縮率を１０％以下であることが好ましい。圧縮の荷重は、特に限定されず、ごく軽くてもよいが、圧縮率が大きく高比重（高密度）のものを成形するときには荷重を大きくする必要がある。
【００２２】
また、「ガラス繊維を所望の圧縮形状に圧縮する」ことは、「軟化点より１０〜１００℃だけ低い温度」あるいは前記別範囲の各温度に保持することより先に行うことが好ましい。
【００２３】
ガラス繊維成形品の成形方法を用いたガラス繊維成形品の用途は、特に限定されないが、真空断熱用コア材を例示できる。
【００２４】
【発明の実施の形態】
本発明を具体化した真空断熱用コア材及びその成形方法の実施形態について説明する。なお、実施形態で記す材料、構成、数値等は例示であって、適宜変更できる。
［実施形態］
（１）付着工程
図１（ａ）〜（ｃ）に示すように、Ｅガラスよりなるガラス繊維をニードリングしてなるニードルマット１（厚さ１０ｍｍ、繊維径９μｍ、嵩密度１００ｋｇ／ｍ^３、バインダ不使用）を、シリカゾル２（日産化学工業（株）製スノーテックスＳＴ２０）を同重量の水３で希釈し、浸漬する。その後、ローラ４にて絞りをかけた。含浸液量は５．５ｋｇ／ｍ^２となり、ガラス繊維に無機バインダが付着した。
【００２５】
（２）圧縮成形工程
次に、図２（ａ）に示すように、１６０℃に加熱した両挟み板５に、絞り後のガラス繊維を狭持し、周縁間に高さ４ｍｍのストッパ６（金属ゲージ）をセットした。該ストッパ６で厚さの減少が規制され、所望の圧縮形状に圧縮される。結局、加熱した両挟み板５による圧縮（熱間プレス）によりニードルマット１は厚さ４ｍｍに圧縮され板状（図２（ｂ））となった。この際の、ガラス繊維１４とシリカゾル２の接合の拡大模式図を図３（ａ）に示す。この工程では、ガラス繊維１４全体を覆っていた水分が蒸発するに従って、シリカゾル２が粉末化し固化することにより、シリカゾル２を介してガラス繊維１４同士が接合され圧縮成形された。
【００２６】
（３）融着工程
次に、図２（ｃ）に示すように、両挟み板５からはずし、無機バインダが固着することで成形されたニードルマット１を、耐火物７の上に載せ、電気炉８に入れてヒータ９により加熱し、Ｅガラス繊維の軟化点８４０℃より６０℃低い７８０℃に３０分保持することにより、ガラス繊維と無機バインダのシリカゾルとの間又はガラス繊維同士の接触点を融着させた。この際のガラス繊維１４とシリカゾル２との間及びガラス繊維１４同士の融着部位１５の拡大模式図を図３（ｂ）に示す。
【００２７】
（４）固化工程
上記３０分の保持後、ニードルマット１を電気炉８から取り出して室温で自然冷却することにより、前記融着を固化させたところ、厚さ４ｍｍ、嵩密度３８０ｋｇ／ｍ^３の真空断熱用コア材が成形された。これは、ガラス繊維２５０ｋｇ／ｍ^３にシリカゾル固形分が１３０ｋｇ／ｍ^３の比率で加味されたことを意味する。
【００２８】
この成形体を評価したところ、平均繊維径９μｍ、繊維長１０〜３０ｍｍ、強熱減量が０．１％以下であり、圧縮率が０．１０ＭＰａ（１．０２ｋｇ／ｃｍ^２）で１０％以下であり、引張強度は１２ｋｇｆ／ｃｍ^２であった。また、５００℃大気雰囲気での引張強度の低下もなく、０．１ＭＰａ（１．０２ｋｇ／ｃｍ^２）加圧による圧縮復元性も１００％で変化がなかった。
【００２９】
図２（ｄ）に示すように、この成形された真空断熱用コア材１１の長さ方向の両面から２枚の被覆材１０で真空断熱用コア材１１を挟みこみ、真空断熱用コア材１１の周囲端面１２を覆うように被覆材１０同士の周辺部を封止材で接着し、真空断熱材１３となった。
【００３０】
なお、挟み板５の材質は、ステンレス鋼に限定されず、例えばセラミックス（アルミナ、ＳｉＣ等）でもよい。挟み板５の面積が小さい場合には、材質の自由度が高いが、挟み板５の面積の大きい場合には、ステンレス鋼では熱膨張による反りが発生して成形しにくくなるため、その問題が少ないセラミックスが好ましい。
【００３１】
なお、本実施形態における温度条件としては、Ｅガラスの軟化点８４０℃よりも３０〜６０℃低い温度に１０〜３０分保持することが好ましい。例えば８１０℃で長時間保持すると、ボード厚さがストッパ６の高さ以下になってしまうおそれがあるため、各要求するサイズに対応した温度と保持時間とが必要である。その他、例えばＣガラスよりなるガラス繊維の場合には、軟化点７６０℃よりも３０〜６０℃低い温度（例えば７００℃）に１０〜３０分保持することが好ましい。
【００３２】
［比較例１］
実施形態で行う融着工程及び固化工程を行わない例
（１）付着工程
Ｅガラスよりなるガラス繊維をニードリングしてなるニードルマット（厚さ１０ｍｍ、繊維９μｍ、密度１００ｋｇ／ｍ^３、バインダ不使用）に、シリカゾル（日産化学工業（株）製スノーテックスＳＴ２０）を同重量の水で希釈し、浸漬後、ローラーにて絞ると、含浸液量は５．５ｋｇ／ｍ^２となり、ガラス繊維に無機バインダが付着した。
【００３３】
（２）圧縮成形工程
１６０℃に加熱した両挟み板に、両挟み板に、絞り後のガラス繊維を設置し、周縁間に高さ４ｍｍのストッパ（金属ゲージ）をセットした。概ね５分間プレスすることで、厚み４ｍｍ、嵩密度３８０ｋｇ／ｍ^３の成形体を得た。ここでは、実施例との比較とするため、加熱処理は行わない。この成形体を評価したところ、平均繊維径９μｍ、繊維長１０〜３０ｍｍ、強熱減量が０．５％であり、圧縮率が０．１０ＭＰａ（１．０２ｋｇ／ｃｍ^２）で１５％であり、引張強度は８ｋｇｆ／ｃｍ^２であった。
【００３４】
比較例１のように、加熱処理をしないで、圧縮率を０．１０ＭＰａ（１．０２ｋｇ／ｃｍ^２）で１０％以下とするには、嵩密度を５００ｋｇ／ｍ^３以上に高める必要がある。この場合は、熱伝導率および真空脱気性の低下による断熱効果の劣化が起こり、また繊維の柔軟性が拘束され圧縮復元性を損なう傾向がみられた。
【００３５】
［比較例２］
実施例に含まれる付着工程及び圧縮成形工程を行わない例
（１）融着工程・固化工程
Ｅガラスよりなるガラス繊維をニードリングしてなるニードルマット（厚さ１２ｍｍ、繊維９μｍ、嵩密度１００ｋｇ／ｍ^３、バインダ不使用）１枚のマットを、両挟み板（ステンレス板（厚さ２ｍｍ、ＳＵＳ３０４））の間に設置し、周縁間に高さ４ｍｍのストッパ（ＳＵＳ３０４）をセットした。
【００３６】
このニードルマットを両挟み板に挟んだまま、電気炉を用いて７８０℃にて３０分加熱後、冷却固化することで、厚さ４ｍｍ、嵩密度３１９ｋｇ／ｍ^３（面方向の線収縮が約３％発生）の成形体を得た。
この成形体を評価したところ、平均繊維径９μｍ、繊維長１０〜３０ｍｍ、強熱減量が０．１％以下であり、圧縮率が０．１０ＭＰａ（１．０２ｋｇ／ｃｍ^２）で５％であった。
【００３７】
この比較例２の方法では、内部の繊維まで熱劣化を生じやすく、やや圧縮復元性を損なう傾向がみられた。また、箱状、管状等の複雑形状への成形や、表面に大きな凹凸を賦形することが困難である。
【００３８】
本発明で述べたような無機バインダで固着してから融着成形する方法を「無機バインダ融着成形」、無機バインダのみで成形する比較例１のような成形方法を「抄造」、無機バインダを用いない比較例２のような成形方法を「融着成形」と呼ぶこととし、その利点及び欠点を前記従来の各成形方法と対比させて次の表１にまとめた。
【００３９】
【表１】

【００４０】
ここで、「単純形状」とは板状、棒状、ブロック状等の単純形状への成形の容易性をいい、「複雑形状」とは箱状、管状等の複雑形状への成形の容易性をいう。また、「耐熱性」とはガラス繊維自体の耐熱性ではなく、ガラス繊維及び他素材を総合した成形品としての耐熱性をいう。ガラス繊維に樹脂等の有機分を加える必要のあるものは有機分の耐熱性が成形品の耐熱性を決めてしまう。
【００４１】
無機バインダ融着成形の利点は次の通りである。
▲１▼ 比較的表層部の熱処理による融着のため、内部の繊維の柔軟性を維持しており、圧縮復元性を損なうこともない。
▲２▼ 治具さえよければ、比較的簡単に大型（大面積）のボードができる。
▲３▼ 有機分を全く含まないので、高温使用時に煙が出ないので、真空状態で使用する場合の真空劣化が、長期にわたって生じない。
▲４▼ 表面の軟らかさや比重（嵩密度）の変更が条件設定で容易にできる。
▲５▼ 無機バインダのみで成形した場合の表面の粉っぽさがない。
▲６▼ 箱状、管状等の複雑形状への成形や、表面に大きな凹凸を賦形することが比較的簡単である。
【００４２】
この無機バインダ融着成形によるガラス繊維成形体の用途は、特に限定されないが、各種断熱容器、各種熱機器等に使用される断熱材（特に断熱用コア材）に好適である。現時点では、４００℃前後で使用する真空断熱容器の断熱用コア材、−２０〜８０℃で使用する真空断熱用コア材（例えば魔法瓶の真空断熱用コア材）が予定されており、主に上記の利点▲３▼を生かした用途である。その他、ケイカル板やセラミックボードが使用されている用途であって、かつ最高５００℃位までの用途に適している。
【００４３】
なお、本発明は前記実施形態の構成に限定されず、例えば以下のように、発明の趣旨から逸脱しない範囲で適宜変更して具体化することもできる。
（１）ニードルマット１の枚数を１枚にし又は重ね枚数を２枚若しくは４枚以上にすること。
（２）種類の異なるニードルマット１を重ねること。
（３）断面コの字型の成形体を２つを組み合わせることで、箱状とすること。
【００４４】
【発明の効果】
以上詳述したように、本発明に係るガラス繊維成形品及びその成形方法によれば、成形品が高温使用に適し、繊維の持つ柔軟性を維持し、複雑形状を比較的容易にかつ安価にできるという優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明の実施形態に係る（ａ）ニードルマット、（ｂ）無機バインダ処理、（ｃ）無機バインダ処理後のローラ絞りを示す説明図である。
【図２】同実施形態に係る（ａ）（ｂ）両挟み板使用図、（ｃ）電気炉内設置図、（ｄ）真空断熱用コア材を示す説明図である。
【図３】同実施形態に係る（ａ）ガラス繊維と無機バインダの接合の拡大模式図、（ｂ）融着後のガラス繊維と無機バインダの接合の拡大模式図を示す。
【符号の説明】
１ニードルマット
２シリカゾル
５挟み板
８電気炉
１１真空断熱用コア材
１４ガラス繊維
１５融着部位[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a glass fiber molded article and a molding method thereof.
[0002]
[Prior art]
Examples of methods for forming molded articles such as mats, boards, and paper from glass fibers include the following.
(1) Felt molding: A method in which short glass fibers are bonded and bonded together with a binder to form a felt mat.
(2) Needling: A method in which long glass fibers are entangled and bonded by needle punching to form a slightly compressed mat. The surface may be coated with a binder.
(3) Papermaking: A method in which glass fibers are put into a binder-added water to form a slurry, and the slurry is scooped up to make paper and then dried, and the glass fibers are bonded and bonded together with a binder. .
As each binder used in the above (1) to (3), organic binders such as starch, silicon, and rubber are common, and inorganic binders such as silica may be mixed with the organic binder. .
[0003]
An example of using a glass fiber molded body in which a glass fiber material is hardened with an inorganic binder is a laminate film having an adsorbent adhered to the glass fiber molded body hardened with the inorganic binder and at least one metal foil for sealing them. There is a heat insulation panel (Japanese Patent Laid-Open No. 63-187084).
[0004]
Further, as a method having an effect of bonding glass fibers, there is a vacuum heat insulating material in which inorganic fibers are acid-treated to bind each contact point with a component eluted from the fibers (Japanese Patent Laid-Open No. 7-167376). ).
[0005]
[Problems to be solved by the invention]
The felt forming, needling, and papermaking have advantages and disadvantages as summarized in Table 1 below, and are applied to applications that take advantage of each advantage. However, there has been no molding method in which the molded product is suitable for high-temperature use, is easily molded into various shapes, and the strength of the molded product is increased. That is, an organic binder is essential for felt molding and papermaking. Therefore, when the molded product is used at a high temperature, smoke is generated due to decomposition of the organic binder, the binding force by the organic binder is lost and heat resistance is lost, or when such a glass fiber molded body is used by vacuum packaging When the organic binder is vaporized, there is a problem that the degree of vacuum is lowered and the heat insulation performance is deteriorated, which is not suitable for high temperature use. On the other hand, since needling does not require a binder, there is no such problem as long as the binder is not covered, but only simple plate-like mats can be molded, or because of the needling point of flying, the molded product There was a problem that it was difficult to increase the strength.
[0006]
When an inorganic binder is used, the inorganic binder powders and scatters to the part where the coating material is sealed, sealing is incomplete, the degree of vacuum is lowered, and the completeness necessary to maintain high heat insulation performance There was a problem that a risk of hindering sealing occurred.
In addition, inorganic binders include silica sol and cement, but there is a problem that the pressure resistance is inferior to that of organic binders.
[0007]
Furthermore, with a binding force of only an inorganic binder, an increase in bulk density is required to reduce the compressibility under pressure of 0.1 MPa (1.02 kg / cm ² ) to 10% or less, and thermal conductivity and vacuum desorption are required. It will lower the temper. On the other hand, when the compression ratio exceeds 10%, there is a problem that the heat insulating container and the bag are significantly recessed by the vacuum force when the core material is put into the heat insulating container and the bag and evacuated.
[0008]
In addition, the method for binding glass fibers by acid treatment has a problem in that an acid component tends to remain in the binding portion, corrosion of a coating material such as stainless steel easily occurs, and the environment is contaminated.
[0009]
The object of the present invention is to provide a glass fiber molded article having a complex shape and a molding method thereof which solve the above-mentioned problems, are suitable for high-temperature use, maintain flexibility of fibers, and relatively easily and inexpensively. There is to do.
[0010]
[Means for Solving the Problems]
To achieve the above object, a glass fiber molded article of the present invention, to be compressed into a desired compressed shape with a fixing between fibers by the inorganic binder of glass fibers are adhered to the glass fibers, the glass fibers The contact points between the glass fiber and the inorganic binder and between the glass fibers are surface- fused at a temperature lower than the softening point of the glass.
[0011]
The glass fiber molded product molding method of the present invention includes an adhesion step of attaching an inorganic binder to glass fibers, compressing the glass fibers into a desired compression shape, and the inorganic binder attached to the glass fibers between the fibers. A compression molding step for maintaining the compressed shape by fixing, and maintaining the glass fiber at a temperature lower by 10 to 100 ° C. than the softening point of the glass fiber, thereby providing a space between the glass fiber and the inorganic binder and the It includes a fusing step for fusing contact points between glass fibers, and a solidifying step for solidifying the fusing by cooling the glass fibers.
[0012]
Although the kind of glass which comprises glass fiber is not specifically limited, A glass, C glass, E glass, T glass etc. can be illustrated. In addition to glass fiber, heat-resistant inorganic fiber other than glass fiber (alumina fiber, ceramic fiber, silica fiber, rock wool, etc.) or heat-resistant metal fiber (stainless steel, chromium-nickel alloy, high nickel alloy, high cobalt alloy) Etc.) can also be mixed. The fiber diameter of the glass fiber is not particularly limited, but is preferably 1 to 30 μm. Although it depends on the degree of vacuum, the thinner the glass fiber, the lower the thermal conductivity and the better the heat insulation performance.
[0013]
Examples of the inorganic binder include silica sol, alumina sol, titania sol, zirconia sol, and water glass. These may be mixed, or ceramic powder and low-melting glass may be added. When ceramic powder is added, powdered titania and silicon nitride with low solid thermal conductivity are preferable. Furthermore, in this case, the air gap is reduced and the gas heat conduction is almost eliminated, so that the vacuum heat insulation performance is improved. On the other hand, when the ceramic powder is added, the heat transfer point of the object increases, and the solid heat conduction through which heat is transferred through the powder increases, so that there is a problem that the vacuum heat insulation performance deteriorates. Therefore, when a glass fiber molded product to which ceramic powder is added is used as a vacuum heat insulating core material, it is important to adjust the addition amount so that the opposite heat conduction can be reduced to the maximum under the temperature conditions.
Furthermore, an organic binder may be added as necessary to enhance the adhesion dispersibility and adhesion of the inorganic binder. The organic component is vaporized and removed by heat treatment in a later step.
[0014]
Although an adhesion process is not specifically limited, The method of immersing the needle mat formed by needling glass fiber in an inorganic binder, and squeezing with a roller can be illustrated.
Although a compression molding process is not specifically limited, The method to compress glass fiber with the heated pinching board can be illustrated.
[0015]
The fusing process is not particularly limited, but the glass fiber fixed and compressed with an inorganic binder is removed from the sandwich plate, and the contact points between the glass fiber and the inorganic binder and between the glass fibers are fused by heating. A method can be illustrated. At this time, the glass fiber is protected from external heat by an inorganic binder. Although heating conditions are not limited, in order to prevent deterioration of the fiber and maintain flexibility, it is preferable to perform the fusion treatment at a temperature lower by 10 to 100 ° C. than the softening point in a short time.
[0016]
The reason why the temperature is set to “a temperature lower by 10 to 100 ° C. than the softening point” is that if the temperature is higher than the upper limit of the range, the glass fiber may be melted too much and shrink in a lump. This is because at a lower temperature, the viscosity of the glass fiber is too high to be fused. More preferably, it is “a temperature lower by 20 to 80 ° C. than the softening point”, and more preferably “a temperature lower by 30 to 60 ° C. than the softening point”.
[0017]
“Temperature lower by 10 to 100 ° C. than the softening point” can be replaced with “temperature at which the viscosity becomes 5 × 10 ⁷ P to 10 ⁹ P” from the viewpoint of the viscosity of the glass constituting the glass fiber. This is because if the viscosity is lower than 5 × 10 ⁷ P, the glass fiber may be melted too much and shrink in a solid state, and if the viscosity is higher than 10 ⁹ P, it is difficult to fuse. More preferably, it is “the temperature at which the viscosity becomes 6 × 10 ⁷ P to ⁸ × 10 ⁸ P”, and more preferably “the temperature at which the viscosity becomes 7 × 10 ⁷ P to 5 × 10 ⁸ P”.
[0018]
Here, a mechanism for fusing the contact points between the glass fibers and the inorganic binder and between the glass fibers will be described as an example. Since glass fibers are amorphous, they do not have the melting point of crystalline substances, and when the temperature is raised, the viscosity decreases continuously with the movement of the primitive, and it moves to liquid. go. In general, the softening point of glass refers to the temperature at a viscosity of 4.5 × 10 ⁷ P (log η = 7.65), which is the lower limit temperature at which glass can be formed. The molding method of the present invention utilizes the viscosity of the glass that continuously changes as described above, and when the viscosity of the glass is slightly lower than 4.5 × 10 ⁷ P, between the glass fiber and the inorganic binder and the glass fiber. Utilizing the phenomenon of mutual fusion at the contact point of each other, surface fusion to the extent that thermal degradation does not occur inside the fiber, and the phenomenon of forming a neck in the sintering process of ceramic powder in a short time is doing. In fact, in terms of phenomena, it seems that resin molding is closer to this mechanism than ceramics sintering. Moreover, since it is a point contact fusion, closed bubbles are not left behind.
[0019]
The “temperature lower by 10 to 100 ° C. than the softening point” or the time for holding each temperature in the different range varies depending on the temperature in the range, and is shortened when the temperature is high (for example, 1 to 20 minutes). ) If the temperature is low, increase the length (for example, 15 to 50 minutes). Further, the same time varies depending on the compression shape and size, and is increased, for example, when the thickness is large and heat is not easily transmitted to the inside.
[0020]
The compression shape is not particularly limited, but it can be molded into complex shapes such as plate shapes (including not only flat plate shapes but also curved plate shapes, corrugated plate shapes, etc.), rod shapes, block shapes, box shapes, tubular shapes, etc. Furthermore, the shaping | molding which shapes a large unevenness | corrugation on the surface can be illustrated.
[0021]
The glass fiber molded product is not particularly limited, but is frequently used with a bulk density of 250 to 480 kg / m ³ and a compression rate of 10% or less at 0.1 MPa pressure. The compression load is not particularly limited and may be very light, but it is necessary to increase the load when molding a material having a high compression ratio and a high specific gravity (high density).
[0022]
Further, “compressing the glass fiber into a desired compression shape” is preferably performed before holding at “a temperature lower by 10 to 100 ° C. than the softening point” or each temperature in the different range.
[0023]
Although the use of the glass fiber molded product using the molding method of the glass fiber molded product is not particularly limited, a vacuum heat insulating core material can be exemplified.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a vacuum heat insulating core material and a molding method thereof embodying the present invention will be described. Note that the materials, configurations, numerical values, and the like described in the embodiments are examples and can be changed as appropriate.
[Embodiment]
(1) Adhesion process As shown in FIGS. 1 (a) to (c), a needle mat 1 (thickness 10 mm, fiber diameter 9 μm, bulk density 100 kg / m ³ , formed by needling glass fibers made of E glass, Silica sol 2 (Snowtex ST20 manufactured by Nissan Chemical Industries, Ltd.) is diluted with water 3 of the same weight and immersed in the binder-free). Thereafter, the roller 4 was squeezed. The amount of impregnating liquid was 5.5 kg / m ² , and the inorganic binder adhered to the glass fiber.
[0025]
(2) Compression molding step Next, as shown in FIG. 2 (a), the glass fiber after drawing is sandwiched between both sandwich plates 5 heated to 160 ° C., and a stopper 6 (height 4 mm between the peripheral edges) A metal gauge) was set. The stopper 6 restricts the thickness from being reduced, and the stopper 6 is compressed into a desired compression shape. Eventually, the needle mat 1 was compressed to a thickness of 4 mm by compression (hot pressing) by the heated sandwiching plates 5 to form a plate shape (FIG. 2B). An enlarged schematic view of the bonding of the glass fiber 14 and the silica sol 2 at this time is shown in FIG. In this step, as the water covering the entire glass fiber 14 evaporates, the silica sol 2 is powdered and solidified, whereby the glass fibers 14 are joined and compressed through the silica sol 2.
[0026]
(3) Fusing Step Next, as shown in FIG. 2 (c), the needle mat 1 formed by removing the both sandwiching plates 5 and fixing the inorganic binder is placed on the refractory 7 It is put into the furnace 8 and heated by the heater 9 and kept at 780 ° C., which is 60 ° C. lower than the softening point of E glass fiber, for 30 minutes, so that the contact point between the glass fiber and the silica sol of the inorganic binder or between the glass fibers. Was fused. An enlarged schematic view of the fused portion 15 between the glass fiber 14 and the silica sol 2 and between the glass fibers 14 at this time is shown in FIG.
[0027]
(4) Solidification step After holding for 30 minutes, the needle mat 1 was taken out of the electric furnace 8 and naturally cooled at room temperature to solidify the fusion. As a result, the thickness was 4 mm and the bulk density was 380 kg / m ³ . A vacuum insulation core material was formed. This means that the silica sol solid content is taken into account at a rate of 130 kg / ^{m 3} to the glass fiber 250 kg / ^{m 3.}
[0028]
When this molded body was evaluated, the average fiber diameter was 9 μm, the fiber length was 10 to 30 mm, the loss on ignition was 0.1% or less, and the compression rate was 0.10 MPa (1.02 kg / cm ² ) and 10% or less. Yes, and the tensile strength was 12 kgf / cm ² . In addition, there was no decrease in tensile strength at 500 ° C. in the air atmosphere, and the compression recovery property by pressurizing 0.1 MPa (1.02 kg / cm ² ) was 100% and there was no change.
[0029]
As shown in FIG. 2 (d), the vacuum heat insulation core material 11 is sandwiched between the two covering materials 10 from both sides in the length direction of the formed vacuum heat insulation core material 11, and the vacuum heat insulation core material 11. The peripheral portions of the covering materials 10 were bonded together with a sealing material so as to cover the peripheral end face 12 of the film, thereby forming a vacuum heat insulating material 13.
[0030]
The material of the sandwich plate 5 is not limited to stainless steel, and may be ceramics (alumina, SiC, etc.), for example. When the area of the sandwiching plate 5 is small, the degree of freedom of the material is high. However, when the area of the sandwiching plate 5 is large, warping due to thermal expansion occurs in stainless steel, which makes it difficult to form. Less ceramic is preferred.
[0031]
In addition, as temperature conditions in this embodiment, it is preferable to hold | maintain for 10 to 30 minutes at the temperature 30-60 degreeC lower than the softening point 840 degreeC of E glass. For example, if the board is held at 810 ° C. for a long time, the board thickness may be less than the height of the stopper 6, so that a temperature and a holding time corresponding to each required size are required. In addition, in the case of glass fiber made of, for example, C glass, it is preferable to hold at a temperature 30 to 60 ° C. lower than the softening point 760 ° C. (eg 700 ° C.) for 10 to 30 minutes.
[0032]
[Comparative Example 1]
Example of not performing the fusing step and the solidifying step performed in the embodiment (1) Adhesion step E Needle mat formed by needling glass fibers made of glass (thickness 10 mm, fibers 9 μm, density 100 kg / m ³ , binder-free) ), Silica sol (Snowtex ST20 manufactured by Nissan Chemical Industries, Ltd.) is diluted with water of the same weight, immersed, and then squeezed with a roller. The amount of impregnating liquid becomes 5.5 kg / m ² , and the glass fiber is inorganic. The binder has adhered.
[0033]
(2) Compression molding process On both sandwich plates heated to 160 ° C., glass fibers after drawing were placed on both sandwich plates, and a stopper (metal gauge) having a height of 4 mm was set between the peripheral edges. By pressing for approximately 5 minutes, a molded body having a thickness of 4 mm and a bulk density of 380 kg / m ³ was obtained. Here, heat treatment is not performed for comparison with the example. When this molded body was evaluated, the average fiber diameter was 9 μm, the fiber length was 10 to 30 mm, the loss on ignition was 0.5%, and the compression rate was 15% at 0.10 MPa (1.02 kg / cm ² ). The tensile strength was 8 kgf / cm ² .
[0034]
As in Comparative Example 1, in order to reduce the compressibility to 10% or less at 0.10 MPa (1.02 kg / cm ² ) without heat treatment, it is necessary to increase the bulk density to 500 kg / m ³ or more. In this case, the heat insulation effect deteriorated due to the decrease in the thermal conductivity and the vacuum degassing property, and the flexibility of the fiber was constrained and the tendency to impair the compression recovery property was observed.
[0035]
[Comparative Example 2]
Example in which the adhesion process and compression molding process included in the examples are not performed (1) Fusion process / solidification process E Needle mat formed by needling glass fibers made of glass (thickness 12 mm, fibers 9 μm, bulk density 100 kg / m ³ , binder not used) One mat was placed between both sandwich plates (stainless steel plate (thickness 2 mm, SUS304)), and a stopper (SUS304) having a height of 4 mm was set between the peripheral edges.
[0036]
This needle mat is sandwiched between both sandwich plates, heated at 780 ° C. for 30 minutes using an electric furnace, and then cooled and solidified, resulting in a thickness of 4 mm and a bulk density of 319 kg / m ³ (the linear shrinkage in the surface direction is approximately 3% generation) was obtained.
When this molded body was evaluated, the average fiber diameter was 9 μm, the fiber length was 10 to 30 mm, the loss on ignition was 0.1% or less, and the compression rate was 5% at 0.10 MPa (1.02 kg / cm ² ). It was.
[0037]
In the method of Comparative Example 2, there was a tendency that thermal degradation was easily caused up to the internal fibers, and the compression restoring property was somewhat impaired. In addition, it is difficult to form a complicated shape such as a box shape or a tubular shape or to form large irregularities on the surface.
[0038]
The method of fusion molding after fixing with an inorganic binder as described in the present invention is “inorganic binder fusion molding”, and the molding method as in Comparative Example 1 in which molding is performed only with an inorganic binder is “papermaking”. The molding method such as Comparative Example 2 that is not used is referred to as “fusion molding”, and the advantages and disadvantages thereof are summarized in the following Table 1 in comparison with the conventional molding methods.
[0039]
[Table 1]

[0040]
Here, “simple shape” means ease of forming into a simple shape such as a plate shape, rod shape, block shape, etc., and “complex shape” means ease of forming into a complicated shape such as box shape or tubular shape. Say. The term “heat resistance” refers not to the heat resistance of the glass fiber itself, but to the heat resistance as a molded product combining the glass fiber and other materials. In the case where it is necessary to add an organic component such as a resin to the glass fiber, the heat resistance of the organic component determines the heat resistance of the molded product.
[0041]
The advantages of the inorganic binder fusion molding are as follows.
{Circle around (1)} Since the surface layer portion is fused by heat treatment, the flexibility of the internal fibers is maintained, and the compression / restoration property is not impaired.
(2) A large (large area) board can be made relatively easily if only a jig is required.
(3) Since no organic content is contained, no smoke is emitted when used at high temperatures, so that no vacuum deterioration occurs when used in a vacuum state over a long period of time.
(4) The softness and specific gravity (bulk density) of the surface can be easily changed by setting the conditions.
(5) There is no powdery surface when molded with only an inorganic binder.
{Circle around (6)} It is relatively easy to form a complex shape such as a box shape or a tubular shape or to form large irregularities on the surface.
[0042]
Although the use of the glass fiber molded body by this inorganic binder fusion molding is not particularly limited, it is suitable for a heat insulating material (particularly a heat insulating core material) used in various heat insulating containers, various heat devices and the like. At present, a core material for heat insulation of a vacuum heat insulating container used at around 400 ° C. and a core material for vacuum heat insulation used at −20 to 80 ° C. (for example, a core material for vacuum heat insulation of a thermos bottle) are planned. This is an application that takes advantage of (3). In addition, it is suitable for applications where a calcium plate or ceramic board is used and up to about 500 ° C.
[0043]
In addition, this invention is not limited to the structure of the said embodiment, For example, as follows, it can also be changed and embodied suitably in the range which does not deviate from the meaning of invention.
(1) The number of needle mats 1 is one, or the number of stacked layers is two or four or more.
(2) Stacking different types of needle mats 1.
(3) To form a box shape by combining two U-shaped shaped sections.
[0044]
【The invention's effect】
As described above in detail, according to the glass fiber molded product and the molding method thereof according to the present invention, the molded product is suitable for high temperature use, maintains the flexibility of the fiber, and makes complex shapes relatively easy and inexpensive. There is an excellent effect of being able to.
[Brief description of the drawings]
FIGS. 1A and 1B are explanatory views showing (a) a needle mat, (b) an inorganic binder process, and (c) a roller aperture after an inorganic binder process according to an embodiment of the present invention.
FIGS. 2A and 2B are diagrams showing use of both sandwiching plates, FIG. 2C is an installation diagram in an electric furnace, and FIG. 2D is an explanatory view showing a core material for vacuum insulation.
FIG. 3 shows (a) an enlarged schematic view of bonding between glass fibers and an inorganic binder according to the embodiment, and (b) an enlarged schematic view of bonding between glass fibers and an inorganic binder after fusion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Needle mat 2 Silica sol 5 Sandwich board 8 Electric furnace 11 Core material 14 for vacuum heat insulation 14 Glass fiber 15 Fusion part

Claims

Glass fiber is compacted into a desired compressed shape fixed to with in between the fibers by the inorganic binder adhering to the glass fiber, the point of contact between and the glass fibers of the glass fiber and inorganic binder, Glass fiber molded product that is surface- fused at a temperature lower than the softening point of glass.

An adhesion step of attaching an inorganic binder to the glass fiber, a compression molding step of compressing the glass fiber into a desired compression shape, and maintaining the compression shape by fixing the inorganic binder attached to the glass fiber between the fibers, A fusing step of fusing the contact points between the glass fibers and the inorganic binder and between the glass fibers by maintaining the glass fibers at a temperature lower by 10 to 100 ° C. than the softening point of the glass fibers; And a solidification step of solidifying the fusion by cooling the glass fiber.

An adhesion step of attaching an inorganic binder to the glass fiber, a compression molding step of compressing the glass fiber into a desired compression shape, and maintaining the compression shape by fixing the inorganic binder attached to the glass fiber between the fibers, A fusing step of fusing the contact points between the glass fibers and the inorganic binder and between the glass fibers by maintaining the glass fibers at a temperature at which the viscosity becomes 5 × 10 ⁷ P to 10 ⁹ P; And a solidification step of solidifying the fusion by cooling the glass fiber.

The method for forming a glass fiber molded article according to claim 2 or 3, wherein in the attaching step, the glass fiber is immersed in an inorganic binder and squeezed.

The said compression molding process is a molding method of the glass fiber molded product of Claim 2 or 3 which compresses the said glass fiber with the heated pinching board.

The method for molding a glass fiber molded article according to claim 2 or 3, wherein the fusing step is performed by removing the glass fiber, which is fixed by the inorganic binder and compression-molded, from a sandwich plate.

The glass fiber molded article according to claim 1, wherein the glass fiber is a needle mat formed by needling glass fiber.

The glass fiber molded article had a volume density of 250~480kg / ^{m 3,} claim 1 fiberglass molded article according to the compression ratio at 0.1MPa pressure is equal to or less than 10%.

The glass fiber molded article according to claim 1 glass fiber molded article, wherein it is a core material for vacuum insulation.

The method for molding a glass fiber molded article according to claim 2 or 3, wherein the glass fiber is a needle mat formed by needling glass fiber.

The glass fiber molded product has a bulk density of 250 to 480 kg / m. ^３3 4. The method for molding a glass fiber molded article according to claim 2, wherein the compression ratio is 10% or less at a pressure of 0.1 MPa.

The method for molding a glass fiber molded product according to claim 2 or 3, wherein the glass fiber molded product is a vacuum heat insulating core material.