JP3799388B2

JP3799388B2 - Flexible inorganic fiber sewing heat insulation structure and manufacturing method thereof

Info

Publication number: JP3799388B2
Application number: JP28108099A
Authority: JP
Inventors: 和之三保; 文人武田; 純一小川; 敏行安治; 美宏川崎
Original assignee: Mitsubishi Heavy Industries Ltd; Nichias Corp; Japan Aerospace Exploration Agency JAXA
Current assignee: Mitsubishi Heavy Industries Ltd; Nichias Corp; Japan Aerospace Exploration Agency JAXA
Priority date: 1999-10-01
Filing date: 1999-10-01
Publication date: 2006-07-19
Anticipated expiration: 2019-10-01
Also published as: JP2001097783A

Description

【０００１】
【発明の属する技術分野】
本発明は、１３００℃を超えるような温度条件下で使用される断熱材として適当な、高度の耐熱性、耐熱衝撃性及び断熱性を有し、複雑な形状を有する筺体への取り付けが容易な可撓性無機繊維質縫製断熱構造体及びその製造法に関するものである。
【０００２】
【従来の技術】
ＮＡＳＡの宇宙往還機・スペースシャトルの表面保護材のように、著しい高温や激しい熱衝撃によく耐え、低密度で断熱性に優れる一方、一定水準以上の強度を備えていることを要求される断熱材としては、耐熱無機繊維を主材とする多孔質板状硬質断熱材が知られている。
【０００３】
この種の断熱材で最初に用いられたものは、バインダーとしてのコロイダルシリカと高純度シリカ繊維との混合物の成形体を１３００℃で焼成して作製されたシリカタイルと呼ばれるものである。その後、シリカ繊維、アルミノシリケート繊維及び酸化ホウ素の混合物からなる多孔質板状硬質断熱材、シリカ繊維及びアルミノボロシリケート繊維の混合物からなる多孔質板状硬質断熱材、シリカ繊維、ムライト繊維及びホウ素化合物粉末の混合物からなる多孔質板状硬質断熱材などが開発され、また、これらの製造方法なども開示されている。
【０００４】
【発明が解決しようとする課題】
しかしながら、これらの多孔質板状硬質断熱材は、高温で焼成を行うことで繊維間融着を生じさせ、強度を発現させることを特徴としているため、これら断熱材の耐熱無機繊維同士は強固に結びついており、可撓性はない。従って、これらを断熱材として用いる際は、取り付ける筺体の形状に合わせた加工が必要であり、航空宇宙用途など機体が複雑形状の場合は表裏とも３次元加工機による加工が必要となるものであった。また、複雑な３次元加工を必要とするため、加工精度や加工による材料ロスを考慮する必要があり、１枚あたりのサイズはおのずと限定される。従って、これら断熱材を取り付ける工数削減には限界があり、非常に高価なものであった。
【０００５】
従って、本発明の目的は、ＮＡＳＡの宇宙往還機・スペースシャトルの表面保護材のように、１３００℃を超えるような温度条件下で使用される断熱材として適当な、高度の耐熱性、耐熱衝撃性及び断熱性を有し、複雑な形状を有する筺体への取り付けが容易な可撓性無機繊維質縫製断熱構造体及びその製造方法を提供するものである。
【０００６】
【課題を解決するための手段】
かかる実情において、本発明者らは鋭意検討を行った結果、互いに特定の配合量としたムライト繊維とシリカ繊維の無機繊維混合物を、特定量の有機質バインダにより縫合時に変形しない強度を有するように絡めて作製された無機繊維質ボードを、耐熱無機繊維織物からなる表層材で挟み込み、これらをフッ素樹脂コーティングを施した耐熱無機連続繊維からなる縫合糸で縫合一体化した後、無機繊維ボード中の有機質バインダを焼失させた無機繊維質縫製断熱構造体が、高度の耐熱性、耐衝撃性及び断熱性を有し、且つ十分な可撓性を発現することを見出し、本発明を完成するに至った。
【０００７】
すなわち、本発明は、ムライト繊維とシリカ繊維の無機繊維混合物を有機質バインダにより縫合時に変形しない強度を有するように絡めて形成した無機繊維質ボードを、耐熱無機繊維織物からなる表層材で挟み込み、これらをフッ素樹脂コーティングを施した耐熱無機連続繊維からなる縫合糸で縫合一体化した後、無機繊維ボード中の有機質バインダを焼失させて得られるものであって、前記無機繊維質ボードは、ムライト繊維を、ムライト繊維及びシリカ繊維の無機繊維混合物中、７０〜９５重量％、シリカ繊維を、前記無機繊維混合物中、５〜３０重量％、有機質バインダを、前記無機繊維混合物に対して、５〜３０重量％、を含有し、前記縫合糸は、前記耐熱無機連続繊維に５〜１５重量％のフッ素樹脂コーティングが施されたものであることを特徴とする可撓性無機繊維質縫製断熱構造体を提供するものである。本発明の可撓性無機繊維質縫製断熱構造体によれば、縫合時、縫合による応力では変形しない十分な強度を有していながら、含有する有機質バインダを焼失させることで十分な可撓性を発現する無機繊維質ボードを、耐熱無機繊維織物及び耐熱無機連続繊維からなる縫合糸で縫合一体化しており、簡単に複雑な形状を有する筺体へもフィットさせることが出来る。また、縫合に用いる耐熱無機連続繊維からなる縫合糸はフッ素樹脂によるコーティングが施され、縫合機械による縫合糸へのダメージ及びかかる断熱材に縫合針が進入する時のダメージを和らげる。
【０００８】
また、本発明は、ムライト繊維７０〜９５重量％とシリカ繊維５〜３０重量％の無機繊維混合物を、該無機繊維混合物に対して５〜３０重量％の有機質バインダ及び必要に応じて該無機繊維混合物に対して２０重量％以下の炭化ケイ素質熱輻射材と共に水中に分散し、得られたスラリー状混合物を真空脱水成形で一体成形し、乾燥することにより、縫合時に変形しない強度を有し、また有機質バインダ焼失後に可撓性を有する無機繊維質ボードを製造し、次いで、該無機繊維質ボードを、耐熱無機繊維織物からなる表層材で挟み込み、これらを５〜１５重量％のフッ素樹脂コーティングが施された耐熱無機連続繊維からなる縫合糸で縫合一体化した後、無機繊維ボード中の有機質バインダを焼失させることを特徴とする可撓性無機繊維質縫製断熱構造体の製造法を提供するものである。本発明の製造法によれば、前記可撓性無機繊維質縫製断熱構造体を確実且つ容易に製造することができる。
【０００９】
【発明の実施の形態】
本発明の実施の形態における可撓性無機繊維質縫製断熱構造体の概略図を図１に示し、縫合状態の一例を図２に示す。図中、可撓性無機繊維質縫製断熱構造体１０は板状の無機繊維質ボード１を耐熱無機繊維織物からなる表層材２、３で挟み込み、耐熱無機連続繊維からなる縫合糸４で縫合一体に形成した構造を有する。
【００１０】
本発明による無機繊維質ボードは、ムライト繊維７０〜９５重量％とシリカ繊維５〜３０重量％の無機繊維混合物を、該無機繊維混合物に対して５〜３０重量％の有機質バインダ及び必要に応じて該無機繊維混合物に対して２０重量％以下の炭化ケイ素質熱輻射材と共に水中に分散し、得られたスラリー状混合物を真空脱水成形で一体成形し、乾燥することにより作製される。
【００１１】
無機繊維質ボードに配合されるムライト繊維は、無機繊維質ボードの基本組成を構成するもので、高耐熱性を得る上で有効である。ムライト繊維の配合割合が７０重量％未満であると、加熱による収縮が大きくなり、高温での使用に耐えられなくなる。また９５重量％を超えると、有機質バインダ焼失後の可撓性が劣り、複雑な形状の筺体などへフィットさせることが出来なくなる。また、ムライト繊維は繊維中にＡｌ₂Ｏ₃ 成分を６０〜８５重量％含有する斜方晶結晶からなる繊維であって、その平均繊維径は２〜５μm 、平均繊維長は０．２〜１０mmのものを用いることが、十分な断熱性能を発揮させる点で好ましい。
【００１２】
無機繊維質ボードに配合されるシリカ繊維は、無機繊維質ボードの断熱性能と有機質バインダ焼失後の可撓性を高いレベルに維持するために有効である。シリカ繊維の配合割合が３０重量％を超えると相対的にムライト繊維が占める比率が低下して耐熱性を損なう結果となる。また５重量％未満では、前述の通り無機繊維質ボードの可撓性を損なうこととなる。また、シリカ繊維としては、ＳｉＯ₂含有率が９５重量％以上の高純度シリカ繊維であって、平均繊維径が０．３〜３μm 、平均繊維長が１〜５mmのものを用いることが好ましい。
【００１３】
無機繊維質ボードに配合される有機質バインダは、無機繊維質ボードを低密度に維持し、かつ縫合時に変形しない強度を与えるのに有効である。有機質バインダの配合割合が５重量％未満であると、乾燥後の無機繊維質ボードは十分な強度が得られずに縫合時に変形を起こす。また、３０重量％を超えると、乾燥後の無機繊維質ボードが固くなりすぎてしまい縫合が困難となる。有機質バインダの市販品の例としては、でんぷん、変成デンプン、水系高分子エマルジョンなどが挙げられる。
【００１４】
また、前記無機繊維質ボードに添加することが可能な炭化ケイ素質熱輻射材は、輻射熱の透過を妨げて製品の断熱性能を一層向上させる。しかし、過度に配合すると製品の密度を好ましくない水準まで高くしてしまう。従って、これを配合する場合、製品の熱伝導率低減効果および密度に対する影響等を考慮するとその配合比率はムライト繊維とシリカ繊維の合計量に対して２０重量％以下、特に５〜１５重量％とすることが好ましい。炭化ケイ素質熱輻射材の具体例（市販品）としては、炭化ケイ素粉末、炭化ケイ素ウィスカ等が挙げられる。
【００１５】
スラリー混合物の調製において、スラリーの固形分濃度は約０．５〜１．５重量％とするのがよい。このスラリーを常法により、所望の形状に脱水成形する。脱水成形は、真空脱水成形が好ましく、プレスを用いるのが一般的である。得られた成形物は有機質バインダーの燃焼温度以下で十分乾燥し、冷却後、必要に応じて切削加工を施すことにより無機繊維質ボードを得る。
【００１６】
前記無機繊維質ボードは、上記方法によって調製され、その特性は乾燥後、該無機繊維質ボードを、耐熱無機繊維織物からなる表層材で挟み込み、これらをフッ素樹脂コーティングを施した耐熱無機連続繊維からなる縫合糸で縫合一体化させる際、変形しない強度を有することであり、更に、縫合一体化に次いで行われる有機質バインダ焼失させた後に可撓性を有するものである。すなわち、無機繊維質ボードは、ムライト繊維とシリカ繊維が充分に絡み合い、それらの交絡点及び空隙を有機質バインダによって固定されているため、縫合時に縫合針の進入によって変形しない強度を発現する。また、焼成工程によりこの有機質バインダを焼失させれば繊維の絡みだけが残り、複雑な形状を有する筺体へもフィットさせることが可能な可撓性を発現する。
【００１７】
本発明の可撓性無機繊維質縫製断熱構造体は、前記無機繊維質ボードを耐熱無機繊維織物からなる表層材で挟み込み、これらをフッ素樹脂コーティングを施した耐熱無機連続繊維からなる縫合糸で縫合一体化した後、無機繊維ボード中の有機質バインダを焼失させて得られる。縫合に用いる耐熱無機連続繊維からなる縫合糸は、縫合時、縫合機械による縫合糸へのダメージ及び縫合針が断熱材に進入する時のダメージを和らげるためにフッ素樹脂によるコーティングが施される。縫合糸にコーティングされるフッ素樹脂の量は、縫合糸に対して、５〜１５重量％とするのがよい。コーティングするフッ素樹脂が５重量％未満では十分な保護膜が出来ず、縫合時に糸切れを起こす。また１５重量％を超えると保護膜が厚くなるため、結果的に縫合糸が固くなってしまい縫合機械では使えなくなる。コーティングに使用するフッ素樹脂は各種樹脂が使用可能であるが、四フッ化エチレン（ＰＴＦＥ）が特に好ましい。また、耐熱無機連続繊維の市販品の例としては、ルビロン（ニチアス社製）、ネクステル（３Ｍ社製）、ニカロン（日本カーボン社製）、チラノ繊維（宇部興産社製）などがある。
【００１８】
耐熱無機連続繊維からなる縫合糸に施すフッ素樹脂コーティングの施工方法は、まず耐熱無機連続繊維を６００℃程度で仮焼を行い、補強用有機繊維や付着する収束剤等を取り除く。その後、縫合糸に対して、５〜１５重量％の付着量となるように調節したフッ素樹脂ディスパージョンに浸し、遠心脱水機により余分な含浸液を脱水、１０５℃で完全に乾燥した後、通風式熱処理炉にて、例えば３６０℃で２時間の熱処理を行って、目的とする縫合糸を得る。
【００１９】
また、無機繊維質ボードを覆う耐熱無機繊維織物としては、各種耐熱無機連続繊維による織物を使用することが可能であるが、炉内へ暴露される面には耐熱温度の高いアルミナ質無機繊維織物や炭化ケイ素質無機繊維織物を使用することが好ましい。また、筺体側温度など、十分に低温に維持できる場合には耐熱温度が低いガラス繊維織物を使用することも可能である。耐熱温度が高い無機繊維織物の市販品の例としては、ルビロンクロス（ニチアス社製）、ネクステルクロス（３Ｍ社製）、ニカロンクロス（日本カーボン社製）、チラノ繊維クロス（宇部興産社製）などがある。
【００２０】
無機繊維質ボードを耐熱無機繊維織物で挟み込み、両者を前記縫合糸で縫合一体化する方法としては、特に制限されないが、経縫合糸と緯縫合糸を用いて編み込むようにして縫合一体化することが好ましく、経糸と緯糸は、各々２〜８糸／cm²となるように使用すればよい。縫合糸で縫合一体化した後、無機繊維ボード中の有機質バインダを焼失させる方法としては、特に制限されないが、熱処理炉にて、３００〜８００℃の温度で２〜５時間の焼成処理を行えばよい。
【００２１】
【実施例】
次に、実施例を挙げて本発明を更に具体的に説明する。
（無機繊維質ボードの作製）
参考例１〜４
下記原料を表１に示す比率で多量の水中に投入し、十分混合してスラリー状にした。ここで、スラリーの固形分濃度は１％であった。得られたスラリーを脱水プレス成形により板状に成形し、得られた成形物を１０５℃で１６時間乾燥を行い、４種類の板状無機繊維質ボードを得た。
【００２２】
（原料）
ムライト繊維；Al₂O₃:SiO₂＝72:28 、平均繊維径２．７μm 、平均繊維長２mm
シリカ繊維；SiO₂99.5% 以上、平均繊維径０．９μm 、平均繊維長２mm
炭化ケイ素ウィスカー；平均繊維長１μm 以下
有機質バインダ；飽和ポリエステル樹脂 SO₃Na 形、分子量16,000
【００２３】
【表１】

【００２４】
参考例５〜９
（フッ素樹脂被覆縫合糸の製造）
表２及び表３に示す施工方法及びフッ素樹脂被覆量により、５種類のフッ素樹脂被覆縫合糸を得た。結果を表３に示す。機械縫合の評価及び機械縫合時の状態は、参考例１の無機繊維質ボードを機械縫合することにより評価した。また、参考例１の無機繊維質ボードはフッ素樹脂被覆縫合糸による縫合時に変形することがなかった。なお、表３中、◎は「優」、○は「良」、×は「不可」を示す。
【００２５】
【表２】

【００２６】
【表３】

【００２７】
実施例１
参考例１の板状無機繊維質ボードを、無機繊維織物「ＢＦ−２０」（３Ｍ社製）で被覆し、次いで、参考例５のフッ素樹脂被覆縫合糸で縫合一体化した。その後、通風式熱処理炉にて４７０℃で３時間の熱処理を行い、有機質バインダーを焼失させ図１及び図２に示すような可撓性無機繊維質縫製断熱構造体を得た。可撓性無機繊維質縫製断熱構造体の特性を評価するため、嵩密度、加熱収縮率及び熱伝導率を測定した。結果を表４に示す。なお、熱伝導率は常圧下における値を示す。
【００２８】
実施例２
参考例２の板状無機繊維質ボードを使用し、参考例６のフッ素樹脂被覆縫合糸を使用した以外は、実施例１と同様の方法で行った。結果を表４に示す。
【００２９】
比較例１
参考例３の板状無機繊維質ボードを使用し、参考例６のフッ素樹脂被覆縫合糸を使用した以外は、実施例１と同様の方法で行った。結果を表４に示す。
【００３０】
比較例２
参考例４の板状無機繊維質ボードを使用し、参考例６のフッ素樹脂被覆縫合糸を使用した以外は、実施例１と同様の方法で行った。結果を表４に示す。
【００３１】
【表４】

【００３２】
表４から、本実施例は１３００℃における加熱でも収縮率は非常に小さい。ＮＡＳＡの宇宙往還機、スペースシャトルの表面保護材のような用途の場合、許容される収縮率は概ね３％以下であるから、本実施例は充分に要求をクリアしている。また、熱伝導率においても本実施例は充分に小さい。実施例１を比較例と比較すると熱伝導率については若干劣るものであるが、実施例２に示すように、熱輻射材を添加すれば比較例を凌駕するほど大幅に断熱性能を向上させることが出来る。なお、実施例１及び実施例２の可撓性無機繊維質縫製断熱構造体は、複雑な形状の筺体への取り付けができる充分な可撓性を示した。
【００３３】
【発明の効果】
本発明の可撓性無機繊維質縫製断熱構造体によれば、高度の耐熱性、耐熱衝撃性及び断熱性を有するため、ＮＡＳＡの宇宙往還機・スペースシャトルの表面保護材のように、１３００℃を超えるような温度条件下でも好適に使用できる。また、複雑な形状を有する筺体への取り付けが極めて容易となるため、低コスト化を実現することができる。また、本発明の製造方法によれば、前記特性を有する可撓性無機繊維質縫製断熱構造体を確実且つ容易に製造することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態における可撓性無機繊維質縫製断熱構造体の概略を示す斜視図である。
【図２】図１の可撓性無機繊維質縫製断熱構造体の縫合状態の一例を示す。
【符号の説明】
１無機繊維質ボード
２耐熱無機繊維織物
３耐熱無機繊維織物
４縫合糸
１０可撓性無機繊維質縫製断熱構造体[0001]
BACKGROUND OF THE INVENTION
The present invention has a high degree of heat resistance, thermal shock resistance and heat insulation suitable as a heat insulating material used under temperature conditions exceeding 1300 ° C., and can be easily attached to a housing having a complicated shape. The present invention relates to a flexible inorganic fiber sewing heat insulating structure and a method for manufacturing the same.
[0002]
[Prior art]
Insulation that is required to have a certain level of strength or better, withstands extremely high temperatures and severe thermal shocks, low density and excellent thermal insulation, like the NASA space shuttle and space shuttle surface protectors As a material, a porous plate-like hard heat insulating material mainly composed of heat-resistant inorganic fibers is known.
[0003]
The first heat insulating material of this type is called a silica tile produced by firing a molded body of a mixture of colloidal silica as a binder and high-purity silica fibers at 1300 ° C. Thereafter, a porous plate-like hard heat insulating material made of a mixture of silica fiber, aluminosilicate fiber and boron oxide, a porous plate-like hard heat insulating material made of a mixture of silica fiber and aluminoborosilicate fiber, silica fiber, mullite fiber and boron compound A porous plate-like hard heat insulating material made of a powder mixture has been developed, and a manufacturing method thereof has also been disclosed.
[0004]
[Problems to be solved by the invention]
However, these porous plate-like hard heat insulating materials are characterized by causing inter-fiber fusion by firing at a high temperature and developing strength. They are tied and not flexible. Therefore, when these are used as heat insulating materials, it is necessary to process them according to the shape of the housing to be attached. When the aircraft has a complicated shape, such as for aerospace applications, both front and back must be processed by a three-dimensional processing machine. It was. Further, since complicated three-dimensional processing is required, it is necessary to consider processing accuracy and material loss due to processing, and the size per sheet is naturally limited. Therefore, the man-hour reduction for attaching these heat insulating materials has a limit and is very expensive.
[0005]
Accordingly, the object of the present invention is to provide a high degree of heat resistance and thermal shock suitable as a heat insulating material used under temperature conditions exceeding 1300 ° C., such as a surface protection material for NASA space shuttles and space shuttles. The present invention provides a flexible inorganic fibrous sewn heat insulating structure that has good properties and heat insulating properties and can be easily attached to a housing having a complicated shape, and a method for manufacturing the same.
[0006]
[Means for Solving the Problems]
In such a situation, the present inventors have intensively studied and, as a result, entangled a mixture of mullite fiber and silica fiber having a specific blending amount with each other so as not to be deformed at the time of stitching with a specific amount of organic binder. The inorganic fiber board produced in this way is sandwiched between surface layers made of heat-resistant inorganic fiber fabrics, and these are stitched together with sutures made of heat-resistant inorganic continuous fibers coated with fluororesin, and then the organic matter in the inorganic fiber board It has been found that the inorganic fiber sewing heat insulating structure in which the binder has been burned out has high heat resistance, impact resistance and heat insulating properties and exhibits sufficient flexibility, and has completed the present invention. .
[0007]
That is, the present invention sandwiches an inorganic fiber board formed by entwining an inorganic fiber mixture of mullite fibers and silica fibers with an organic binder so as not to be deformed at the time of stitching with a surface layer material made of a heat-resistant inorganic fiber fabric, Is obtained by burning off the organic binder in the inorganic fiber board after being integrated with a suture made of heat-resistant inorganic continuous fiber coated with a fluororesin coating, and the inorganic fiber board contains mullite fibers. , 70 to 95 wt% in the inorganic fiber mixture of mullite fiber and silica fiber, 5 to 30 wt% in the inorganic fiber mixture, The organic binder contains 5 to 30% by weight based on the inorganic fiber mixture, and the suture is obtained by applying 5 to 15% by weight of a fluorine resin coating to the heat-resistant inorganic continuous fiber. A flexible inorganic fibrous sewing heat insulating structure characterized by the above is provided. According to the heat insulation structure of the flexible inorganic fiber sewing of the present invention, sufficient flexibility can be obtained by burning out the organic binder contained, while having sufficient strength not to be deformed by the stress caused by stitching at the time of stitching. The developed inorganic fiber board is stitched and integrated with a suture made of a heat-resistant inorganic fiber fabric and heat-resistant inorganic continuous fibers, and can be easily fitted to a housing having a complicated shape. In addition, a suture made of heat-resistant inorganic continuous fibers used for sewing is coated with a fluororesin, so that damage to the suture by the sewing machine and damage when the suture needle enters the heat insulating material are alleviated.
[0008]
The present invention also provides an inorganic fiber mixture of 70 to 95% by weight of mullite fibers and 5 to 30% by weight of silica fibers, an organic binder of 5 to 30% by weight with respect to the inorganic fiber mixture, and optionally the inorganic fibers. Dispersed in water together with 20 wt% or less of silicon carbide thermal radiant with respect to the mixture, the slurry-like mixture obtained is integrally formed by vacuum dehydration molding, and dried, thereby having a strength that does not deform during stitching, In addition, after the organic binder is burned down, a flexible inorganic fiber board is manufactured, and then the inorganic fiber board is sandwiched with a surface layer material made of heat-resistant inorganic fiber fabric, and these are coated with 5 to 15% by weight of a fluororesin coating. after decorated with suture integrated by suture made of heat inorganic continuous fibers, flexible inorganic fiber sewing, characterized in that burning off the organic binder in the inorganic fiber board There is provided a method for producing the thermal structure. According to the manufacturing method of the present invention, the flexible inorganic fibrous sewing heat insulating structure can be reliably and easily manufactured.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic view of a flexible inorganic fiber sewing heat insulation structure according to an embodiment of the present invention, and FIG. 2 shows an example of a stitched state. In the drawing, a flexible inorganic fiber sewing heat insulating structure 10 is formed by sandwiching a plate-like inorganic fiber board 1 with

surface layer materials

2 and 3 made of heat-resistant inorganic fiber fabric and integrally stitching with a suture thread 4 made of heat-resistant inorganic continuous fibers. It has the structure formed in.
[0010]
The inorganic fiber board according to the present invention comprises an inorganic fiber mixture of 70 to 95% by weight of mullite fibers and 5 to 30% by weight of silica fibers, an organic binder of 5 to 30% by weight with respect to the inorganic fiber mixture, and if necessary. The inorganic fiber mixture is produced by dispersing it in water together with a silicon carbide thermal radiant of 20% by weight or less, and integrally forming the resulting slurry mixture by vacuum dehydration molding and drying.
[0011]
The mullite fiber blended in the inorganic fiber board constitutes the basic composition of the inorganic fiber board and is effective in obtaining high heat resistance. When the blending ratio of the mullite fiber is less than 70% by weight, the shrinkage due to heating becomes large, and it cannot be used at high temperature. On the other hand, if it exceeds 95% by weight, the flexibility after burning out the organic binder is inferior, and it becomes impossible to fit into a complex-shaped housing. The mullite fiber is a fiber composed of orthorhombic crystals containing 60 to 85% by weight of Al ₂ O ₃ component in the fiber, the average fiber diameter is 2 to 5 μm, and the average fiber length is 0.2 to 10 mm. It is preferable to use those having sufficient heat insulating performance.
[0012]
Silica fibers blended in the inorganic fiber board are effective for maintaining the heat insulation performance of the inorganic fiber board and the flexibility after burning the organic binder at a high level. When the blending ratio of the silica fibers exceeds 30% by weight, the ratio occupied by the mullite fibers is relatively lowered, resulting in a deterioration in heat resistance. If it is less than 5% by weight, the flexibility of the inorganic fiber board is impaired as described above. Further, as the silica fiber, it is preferable to use a high-purity silica fiber having a SiO ₂ content of 95% by weight or more, an average fiber diameter of 0.3 to 3 μm, and an average fiber length of 1 to 5 mm.
[0013]
The organic binder blended in the inorganic fiber board is effective for maintaining the inorganic fiber board at a low density and giving a strength that does not deform during stitching. If the blending ratio of the organic binder is less than 5% by weight, the dried inorganic fiber board cannot obtain sufficient strength and is deformed at the time of sewing. On the other hand, if it exceeds 30% by weight, the dried inorganic fiber board becomes too hard and it becomes difficult to sew. Examples of commercially available organic binders include starch, modified starch, and water-based polymer emulsion.
[0014]
Moreover, the silicon carbide-based heat radiation material that can be added to the inorganic fiber board prevents the transmission of radiation heat and further improves the heat insulation performance of the product. However, excessive blending increases the density of the product to an undesirable level. Therefore, when this is blended, the blending ratio is 20% by weight or less, particularly 5 to 15% by weight with respect to the total amount of mullite fiber and silica fiber in consideration of the effect of reducing the thermal conductivity and the density of the product. It is preferable to do. Specific examples (commercially available products) of the silicon carbide-based heat radiation material include silicon carbide powder and silicon carbide whisker.
[0015]
In the preparation of the slurry mixture, the solid content concentration of the slurry should be about 0.5 to 1.5% by weight. This slurry is dehydrated and molded into a desired shape by a conventional method. The dehydration molding is preferably vacuum dehydration molding, and a press is generally used. The obtained molded product is sufficiently dried below the combustion temperature of the organic binder, cooled, and then subjected to cutting as necessary to obtain an inorganic fiber board.
[0016]
The inorganic fiber board is prepared by the above-mentioned method, and its characteristics are that after drying, the inorganic fiber board is sandwiched with a surface layer material made of heat-resistant inorganic fiber fabric, and these are made of heat-resistant inorganic continuous fibers subjected to fluororesin coating. When the suture is integrated with the suture, the strength is not deformed. Furthermore, the organic binder is burnt down after the suture integration and has flexibility. That is, the inorganic fiber board exhibits sufficient strength that the mullite fiber and the silica fiber are sufficiently entangled and their entanglement points and voids are fixed by the organic binder, so that they are not deformed by the entry of the suture needle during sewing. Moreover, if this organic binder is burned away by the firing step, only the entanglement of the fibers remains, and the flexibility that can be fitted to a housing having a complicated shape is expressed.
[0017]
The flexible inorganic fiber sewing heat insulating structure of the present invention is a structure in which the inorganic fiber board is sandwiched between surface layers made of heat-resistant inorganic fiber fabric, and these are sutured with sutures made of heat-resistant inorganic continuous fibers coated with a fluororesin. After the integration, the organic binder in the inorganic fiber board is burned off. A suture made of heat-resistant inorganic continuous fibers used for sewing is coated with a fluororesin in order to reduce damage to the suture by the sewing machine and damage when the suture needle enters the heat insulating material at the time of sewing. The amount of the fluororesin coated on the suture is preferably 5 to 15% by weight with respect to the suture. If the fluororesin to be coated is less than 5% by weight, a sufficient protective film cannot be formed, and thread breakage occurs during sewing. On the other hand, if it exceeds 15% by weight, the protective film becomes thick, and as a result, the suture thread becomes hard and cannot be used in the suture machine. Various resins can be used as the fluororesin used for coating, but ethylene tetrafluoride (PTFE) is particularly preferable. Examples of commercially available heat-resistant inorganic continuous fibers include Rubylon (manufactured by Nichias), Nextel (manufactured by 3M), Nicalon (manufactured by Nippon Carbon Co., Ltd.), and Tyranno fiber (manufactured by Ube Industries).
[0018]
The fluororesin coating is applied to the suture made of heat-resistant inorganic continuous fibers. First, the heat-resistant inorganic continuous fibers are calcined at about 600 ° C. to remove the reinforcing organic fibers and the adhering sizing agent. Thereafter, the suture is immersed in a fluororesin dispersion adjusted to 5 to 15% by weight, and the excess impregnating solution is dehydrated by a centrifugal dehydrator and completely dried at 105 ° C. For example, heat treatment is performed for 2 hours at 360 ° C. in a heat treatment furnace to obtain a target suture.
[0019]
In addition, as the heat-resistant inorganic fiber fabric covering the inorganic fiber board, it is possible to use a fabric made of various heat-resistant inorganic continuous fibers, but the surface exposed to the furnace is an alumina inorganic fiber fabric having a high heat resistance temperature. It is preferable to use a silicon carbide inorganic fiber fabric. Further, when the temperature on the housing side can be maintained at a sufficiently low temperature, a glass fiber woven fabric having a low heat resistance temperature can be used. Examples of commercially available inorganic fiber fabrics with high heat resistance include Rubylon cloth (Nichias), Nextel cloth (3M), Nicalon cloth (Nihon Carbon), Tyranno fiber cloth (Ube Industries). .
[0020]
The method for sandwiching the inorganic fiber board with the heat-resistant inorganic fiber fabric and integrating the two with the suture is not particularly limited, but it is possible to sew and integrate by using a suture and a weft suture. Preferably, the warp and the weft may be used so as to be ² to 8 yarns / cm ² , respectively. Although it does not restrict | limit especially as a method to burn off the organic binder in an inorganic fiber board after stitching together with a suture thread, if a baking process is performed at a temperature of 300 to 800 ° C. for 2 to 5 hours in a heat treatment furnace. Good.
[0021]
【Example】
Next, the present invention will be described more specifically with reference to examples.
(Production of inorganic fiber board)
Reference Examples 1-4
The following raw materials were put in a large amount of water at the ratio shown in Table 1, and mixed well to form a slurry. Here, the solid content concentration of the slurry was 1%. The obtained slurry was formed into a plate shape by dehydration press molding, and the obtained molded product was dried at 105 ° C. for 16 hours to obtain four types of plate-like inorganic fibrous boards.
[0022]
(material)
Mullite fiber; Al ₂ O ₃ : SiO ₂ = 72: 28, average fiber diameter 2.7 μm, average fiber length 2 mm
Silica fiber: SiO ₂ 99.5% or more, average fiber diameter 0.9μm, average fiber length 2mm
Silicon carbide whisker; Average fiber length of 1 μm or less Organic binder; Saturated polyester resin SO ₃ Na type, molecular weight 16,000
[0023]
[Table 1]

[0024]
Reference Examples 5-9
(Manufacture of fluororesin-coated sutures)
Five types of fluororesin-coated sutures were obtained by the construction methods and fluororesin coating amounts shown in Tables 2 and 3. The results are shown in Table 3. Evaluation of machine stitching and the state at the time of machine stitching were evaluated by machine stitching the inorganic fiber board of Reference Example 1. In addition, the inorganic fibrous board of Reference Example 1 was not deformed at the time of sewing with a fluororesin-coated suture. In Table 3, “◎” indicates “excellent”, “◯” indicates “good”, and “×” indicates “impossible”.
[0025]
[Table 2]

[0026]
[Table 3]

[0027]
Example 1
The plate-like inorganic fiber board of Reference Example 1 was covered with an inorganic fiber fabric “BF-20” (manufactured by 3M), and then stitched together with the fluororesin-coated suture of Reference Example 5. Thereafter, heat treatment was performed at 470 ° C. for 3 hours in a ventilated heat treatment furnace, and the organic binder was burned off to obtain a flexible inorganic fibrous sewing heat insulating structure as shown in FIGS. In order to evaluate the characteristics of the flexible inorganic fibrous sewing heat insulating structure, the bulk density, the heat shrinkage rate and the thermal conductivity were measured. The results are shown in Table 4. In addition, thermal conductivity shows the value under a normal pressure.
[0028]
Example 2
The same procedure as in Example 1 was performed except that the plate-like inorganic fiber board of Reference Example 2 was used and the fluororesin-coated suture of Reference Example 6 was used. The results are shown in Table 4.
[0029]
Comparative Example 1
The same procedure as in Example 1 was performed except that the plate-like inorganic fiber board of Reference Example 3 was used and the fluororesin-coated suture of Reference Example 6 was used. The results are shown in Table 4.
[0030]
Comparative Example 2
The same procedure as in Example 1 was performed except that the plate-like inorganic fiber board of Reference Example 4 was used and the fluororesin-coated suture of Reference Example 6 was used. The results are shown in Table 4.
[0031]
[Table 4]

[0032]
From Table 4, the shrinkage rate of this example is very small even when heated at 1300 ° C. In the case of applications such as NASA space shuttles and space shuttle surface protection materials, the allowable shrinkage rate is approximately 3% or less, so this embodiment sufficiently satisfies the requirements. Also, this example is sufficiently small in terms of thermal conductivity. When Example 1 is compared with the comparative example, the thermal conductivity is slightly inferior, but as shown in Example 2, if the heat radiating material is added, the heat insulation performance is greatly improved so as to surpass the comparative example. I can do it. In addition, the flexible inorganic fiber sewing heat insulation structure of Example 1 and Example 2 showed sufficient flexibility which can be attached to a complex-shaped housing.
[0033]
【The invention's effect】
According to the flexible inorganic fiber sewing heat insulation structure of the present invention, since it has high heat resistance, heat shock resistance and heat insulation, it is 1300 ° C. like the surface protection material of NASA space shuttles and space shuttles. It can be suitably used even under temperature conditions exceeding. Moreover, since the attachment to the housing having a complicated shape is extremely easy, the cost can be reduced. Moreover, according to the manufacturing method of this invention, the flexible inorganic fiber sewing heat insulation structure which has the said characteristic can be manufactured reliably and easily.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an outline of a flexible inorganic fibrous sewing heat insulating structure in an embodiment of the present invention.
2 shows an example of a stitched state of the flexible inorganic fiber sewing heat insulation structure of FIG. 1; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inorganic fiber board 2 Heat resistant inorganic fiber fabric 3 Heat resistant inorganic fiber fabric 4 Suture 10 Flexible inorganic fiber sewing heat insulation structure

Claims

An inorganic fiber board formed by entwining an inorganic fiber mixture of mullite fibers and silica fibers with an organic binder so as not to be deformed when stitched is sandwiched between surface layers made of heat-resistant inorganic fiber fabric, and these are coated with a fluororesin coating. After being integrated with a suture made of heat-resistant inorganic continuous fiber, the organic binder in the inorganic fiber board is burned off,
The inorganic fiber board comprises mullite fibers in an inorganic fiber mixture of mullite fibers and silica fibers in an amount of 70 to 95% by weight, silica fibers in an inorganic fiber mixture in an amount of 5 to 30% by weight, The organic binder contains 5 to 30% by weight based on the inorganic fiber mixture, and the suture is obtained by applying 5 to 15% by weight of a fluorine resin coating to the heat-resistant inorganic continuous fiber. A flexible inorganic fiber sewing heat insulating structure characterized by the above.

The mullite fiber has an average fiber diameter of 2 to 5 μm and an average fiber length of 0.2 to 10 mm , and the silica fiber has an average fiber diameter of 0.3 to 3 μm and an average fiber length of 1 to 5 mm. The flexible inorganic fiber sewing heat insulation structure according to claim 1,

The inorganic fibrous board, further, (D) a silicon carbide heat radiation member, wherein the inorganic fiber mix, flexible inorganic claim 1 or 2 wherein, characterized in that it contains 20 wt% or less Fiber sewing insulation structure.

An inorganic fiber mixture of 70 to 95% by weight of mullite fibers and 5 to 30% by weight of silica fibers, 5 to 30% by weight of organic binder with respect to the inorganic fiber mixture and optionally 20% with respect to the inorganic fiber mixture % Of silicon carbide-based heat radiating material is dispersed in water, and the resulting slurry mixture is integrally formed by vacuum dehydration molding and dried, so that it does not deform when stitched. Manufacturing an inorganic fiber board having flexibility, and then sandwiching the inorganic fiber board with a surface layer material made of a heat-resistant inorganic fiber fabric, these being heat-resistant and inorganic continuous coated with 5 to 15% by weight of a fluororesin coating Fabrication of a flexible inorganic fiber sewing heat insulating structure characterized in that an organic binder in an inorganic fiber board is burned out after being integrated with a suture made of fibers. .