JP3548151B2

JP3548151B2 - Vacuum insulation material and method of manufacturing the same

Info

Publication number: JP3548151B2
Application number: JP2001349503A
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: 2001-11-14
Filing date: 2001-11-14
Publication date: 2004-07-28
Anticipated expiration: 2021-11-14
Also published as: JP2003148687A

Description

【０００１】
【発明の属する技術分野】
本発明は、真空断熱材及びその製造方法に関するものである。
【０００２】
【従来の技術】
従来、真空断熱材としては、無機質繊維よりなるニードリングマット、フェルト、ブランケット等を断熱容器や袋内に収納し、その後真空にして密着したものや、無機繊維を無機バインダで全体を強固に成形し、断熱容器や袋内に収納し、その後真空にして密着したものが知られている。
【０００３】
【発明が解決しようとする課題】
無機質繊維よりなるニードリングマット、フェルト、ブランケット等を断熱容器や袋に収納し真空排気した真空断熱材の場合、マットやフェルトの密度むら又は繊維マットの有する圧縮変形性によって、断熱容器や袋が波打ち又は凹むという問題を有する。また、アルミ箔に収納した場合には高温で使用するとアルミ自身からの放射により断熱性が損なわれるという問題を有する。
【０００４】
また、無機バインダで全体を強固に成形した無機質繊維を断熱容器や袋内に収納し、真空排気した真空断熱材の場合、真空排気時の凹みは少ないが、無機バインダで全体を固められているため、素焼きの磁器のように弾力性がなく、真空排気時に割れが発生し、断熱性能が低下する。これは、耐火物のように脆性破壊が生じやすい構造であるとイメージできる。またこの場合は、多量の無機バインダを要し、さらに、真空排気時に成形内部にある気泡の脱気が難しく、真空断熱材として長時間使用すると、この気泡から発生するガスのため真空劣化が起こり断熱性能の寿命が短くなる。また、断熱部材として容器である断熱容器や袋に入れ真空排気した場合、圧縮率が１０％を越えると、真空力で容器である断熱容器や袋が顕著に凹むという問題点を有するので、この場合、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という問題点がある。
【０００５】
さらに、有機バインダを用いた場合、無機バインダの使用時と比べ耐圧性と弾力性に優れるが、真空包装後に高温になると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危険があり、高温下での使用ができないという問題がある。
【０００６】
本発明は、上記課題を解決し、高温使用に適し、十分な耐圧性を有しながら、より軽量で表面の粉っぽさを低減し、繊維の持つ柔軟性を維持しており、断熱性能を長期間維持でき、さらに、比較的容易に製造できる真空断熱材を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するために、本発明は次の手段（１）（２）を採った。
（１）本発明の真空断熱材は、容器内又は袋内に繊維よりなる断熱部材を充填するとともに真空排気した状態で容器又は袋を密封してなる真空断熱材において、容器の壁又は袋が真空排気時に内外の気圧差で凹む又は変形するのを内側から支えて抑えることができるよう断熱部材の一部に主に無機バインダにより繊維の交点を結着して強固にした強固部を設け、断熱部材が真空排気時に容器の壁又は袋からの圧縮応力により割れるの防ぎ得るよう断熱部材の残部を前記結着の無い又は相対的に少ない柔軟部としたことを特徴とする。なお、母材として使用する「繊維よりなる断熱部材」の種類によっては、既に全体に無機バインダが含まれているものがあるが、その一部にさらに主に無機バインダを付着させて強固部とし、その残部をそのまま使用して柔軟部としてもよい。
【０００８】
（２）本発明の真空断熱材の製造方法は、容器内又は袋内に断熱部材を充填するとともに真空排気した状態で容器又は袋を密封してなる真空断熱材の製造方法において、容器内又は袋内に断熱部材を充填する前に、容器の壁又は袋が真空排気時に内外の気圧差で凹む又は変形するのを内側から支えて抑えることができるよう断熱部材の一部に主に水溶性の無機バインダを付着させて乾燥させることにより繊維の交点を結着して強固にした強固部を設け、断熱部材が真空排気時に容器の壁又は袋からの圧縮応力により割れるの防ぎ得るよう断熱部材の残部を前記結着の無い又は相対的に少ない柔軟部とすることを特徴とする。
【０００９】
上記の手段（１）（２）において、「容器」は、真空状態にした際に、断熱部材の全面を被覆し、真空状態を長期間継続することができ、断熱部材としての性能を妨害しないものであればよく、特定の構造、形状、寸法等に限定されない。容器の材料としては、特に限定されないが、通常のステンレス鋼（銅メッキ品等も含む）、耐熱鋼、ガス発生量の少ない無酸素銅等を例示できる。
【００１０】
「繊維」は、特に限定されないが、無機繊維が主成分であることが好ましい。無機繊維としてはガラス繊維、アルミナやシリカ等のセラミック繊維、スラグウール繊維、又はロックウール繊維を例示できる。また、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）を少量混合することもでき、その場合、断熱性能は多少低下するが、耐熱性は高くなる。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。
【００１１】
「主に無機バインダ」とは、無機バインダのみである場合のみならず、無機バインダを主材とし、有機バインダを添加した場合も含む意味である。
【００１２】
「無機バインダ」としては、繊維間のバインダとして働くものであれば特に限定されず、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、活性シリカ、粘土鉱物、重リン酸アルミ、セメント系を例示できる。これらの無機バインダは混合して使用してもよい。また、特に限定されないが、活性シリカや重リン酸アルミは、シリカゾル等の結合力を強化する作用があり、混合使用することも好ましい。さらに、セラミック粉体を添加しても好ましい。
セラミック粉体を添加する場合は、固体熱伝導率の低い粉体、チタニア、窒化珪素等が好ましい。セラミック粉体を添加することによって、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。しかし、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。そのため、真空断熱材として使われる温度条件と真空条件にて、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。
【００１３】
「有機バインダ」としては、特に限定されず、澱粉系、シリコン系、ゴム系を例示できる。
【００１４】
「割れる」とは、断熱部材の厚さ方向にわたって亀裂が進展することをいい、断熱部材の表面部に亀裂が生じてもそれが厚さ方向に進展しない場合は含まない。
【００１５】
「結着の無い又は相対的に少ない」とは、強固部と比べて無機バインダによる結着が少ないことを意味する。例えば、母材として使用する「繊維よりなる断熱部材」の種類によっては、既に全体に無機バインダが含まれているものがあるが、その一部にさらに主に無機バインダを追加的に付着させて強固部とし、その残部をそのまま（無機バインダを追加的に付着させずに）柔軟部としてもよい。
【００１６】
また、無機バインダの付着前の断熱部材は、特に限定されないが、０．１ＭＰａ（１．０２ｋｇ／ｃｍ^２）加圧で、圧縮率が１０％以上の柔軟性を有することが好ましく、付着後の断熱部材は、特に限定されないが、嵩密度が１００〜４００ｋｇ／ｍ^３で、０．１ＭＰａ加圧にて圧縮率が１０％以下であることが好ましい。さらに、断熱部材の厚さは、特に限定されないが、３０〜１００ｍｍが好ましい。また、特に限定されないが、断熱部材の表面に付着する場合、強固部の無機バインダの厚さは１０ｍｍ以下が好ましく、残部の無機バインダが付着していない柔軟部の厚さは２０ｍｍ以上が好ましい。
【００１７】
「断熱部材の一部に…強固部」及び「断熱部材の残部を…柔軟部」におけるそれぞれの部位の組合せとしては、次の態様を例示できる。
ａ容器の壁又は袋に接する断熱部材の表面部の略全体に強固部を設け、表面部より内側の断熱部材の内部を柔軟部とする。
ｂ断熱部材の表面部の一部に強固部を分割するように柔軟部を設けて、圧縮応力により強固部に亀裂が生じるのを防ぐようにする。
ｃ容器の壁又は袋に接する断熱部材の表面部及び表面部より内側の内部に強固部を複数の島状に分散させて設け、断熱部材の残部を柔軟部とする。
【００１８】
上記の手段（１）（２）のように、主に無機バインダにて繊維の各交点を結着させることで強固部を形成し、真空引きによる容器内壁又は袋からの圧縮応力の伝播を拡散緩和することで成形形状を維持し、仮に強固部に亀裂が発生しても、柔軟部にて亀裂の進展を阻止することができ、高い靭性を維持できる断熱部材となる。
【００１９】
無機バインダを付着する際に、必要に応じて無機バインダの付着量を調整するために、前記の通り有機バインダを添加し増粘してもよい。有機バインダ内の有機分は後工程の加熱処理で気化し排除する。付着方法は特に限定されないが、繊維の成形体の毛細管作用を利用した少量浸漬含浸方法、ハケ塗り、スプレー又はスポンジローラーによる塗布方法等を例示できる。
【００２０】
容器内壁又は袋からの圧縮応力のメカニズムは、内部が水のような材料であれば、パスカルの原理で一様な応力分布を示すが、繊維の成形体の場合は成り立たず、内壁に接触する繊維および各交点から変形する繊維、あるいは交点でバラける繊維、押しつぶれる繊維等により伝達される。従って、繊維又は繊維各交点の強度を高めることで、圧縮に対する抵抗力が高まり、内圧を受ける繊維交点数の増加に伴い、応力を拡散することで圧縮率の低減を図ることができる。
【００２１】
【発明の実施の形態】
本発明を具体化した真空断熱材及びその製造方法の実施形態について説明する。なお、各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。
【００２２】
［第一実施形態］
図１は第一実施形態の真空断熱材７を、図２（ａ）は該真空断熱材７に用いた断熱部材６を示している。この真空断熱材７は、ステンレス鋼製の容器５内に主にセラミック繊維３よりなる断熱部材６を充填するとともに真空排気した状態で、容器周辺部８を封止剤で密封してなるものである。断熱部材６の素材には、セラミック繊維３を主成分とする成形平板（寸法６００ｍｍ×９００ｍｍ×厚さ５０ｍｍ、繊維径２〜１０μｍ、有機バインダ不使用）が用いられている。
【００２３】
容器５の壁が真空排気時に内外の気圧差で凹むのを内側から支えて防ぎ得るように、断熱部材６の一部、ここでは容器５の壁に接する断熱部材６の両表面部の略全体には、無機バインダ４の付着により繊維３の表面を成膜するとともに繊維３どうしの交点を結着して強固にした強固部１が設けられている（図１（ｂ）参照）。無機バインダ４の付着量（乾燥後の固形分）は、後述する実施例▲１▼〜▲４▼では１００〜８００ｇ／ｍ^２であるが、この範囲に限定されるものではなく、例えば５０〜１０００ｇ／ｍ^２でもよい。また、断熱部材６が真空排気時に容器５の壁からの圧縮応力により割れるの防ぎ得るように、断熱部材６の残部、ここでは表面部より内側の断熱部材６の内部は、前記無機バインダ４による成膜及び結着の無い（又は相対的に少ない）柔軟部２とされている。
【００２４】
この真空断熱材７は次の方法により製造したものである。
（１）付着工程
セラミック繊維３の成形平板の両表面の略全体に、市販の水溶性の無機バインダ４（ニューライフ技術研究所社製ＮＫボンドＴＡ−１０）を水で３倍に希釈し、スポンジローラーにて塗布して付着させた。
（２）乾燥工程
上記無機バインダ４付着後のセラミック繊維３の成形平板を２００℃の熱風乾燥炉内で３０分保持するという条件で、無機バインダ４を乾燥硬化させることにより、前記の断熱部材６を得た。断熱部材６の表面部は、乾燥後の無機バインダ４が繊維３の表面を成膜するとともに交点を結着したため前記強固部１を形成した。断熱部材６の残部は、前記柔軟部２となった。
（３）真空排気工程
ステンレス製の容器５に断熱部材６を充填し、真空度が１００Ｐａ（０．７６Ｔｏｒｒ）となるよう真空排気（真空引き）した状態で、周辺部８を封止剤で密封し、真空断熱材７を完成させた。
【００２５】
無機バインダ４の総付着量（乾燥前の液量及び乾燥後の固形分）を４点変えて設定した第一実施形態の断熱部材６である実施例▲１▼〜▲４▼と、無機バインダ４を付着させない（それ以外は第一実施形態と同様）未処理の断熱部材である比較例▲１▼と、無機バインダ４でセラミック繊維３を全含浸した（それ以外は第一実施形態と同様）断熱部材である比較例▲２▼とについて、嵩密度、圧縮率、厚み寸法復元性、及びたわみ量を測定した結果を表１に示す。
【００２６】
【表１】

【００２７】
表１に示すように、未処理の比較例▲１▼の場合、加圧力０．１０ＭＰａで圧縮率が１５．８％となるため、容器５に入れて真空状態にした場合に凹むという問題が起こる。また、全含浸の比較例▲２▼の場合、圧縮率については問題はないが、嵩密度が増し、柔軟性がないため、表面に発生した亀裂や欠けが内部まで進展して割れに至り、断熱性能の低下が問題となる。
これに対し、実施例▲１▼〜▲４▼ではセラミック繊維３の成形平板に無機バインダ４（１００〜８００ｇ／ｍ^２）を付着した場合は、加圧力０．１０ＭＰａで圧縮率が３．２〜４．６％と十分な耐圧性を示しながら、厚みの寸法復元性からわかるように、繊維の持つ柔軟性を維持できる。
【００２８】
第一実施形態の断熱部材６を用いた真空断熱材７による作用効果は、次の通りである。
（１）無機バインダの付着している強固部１があるため、十分な耐圧性を有し、容器５や袋に入れて真空排気した場合、断熱部材６の圧縮変形性によって容器５や袋の凹みや変形を抑えることができる。
（２）前記真空排気による圧縮力で断熱部材６の表面（強固部１）に亀裂が生じても、内部の柔軟部２にて亀裂の進展を阻止することができ、断熱性能の劣化を防止することができる。
（３）使用する無機バインダ４の量が減少するため、表面の粉っぽさを低減でき、容器５を密封する際、封止が不完全となって真空度が落ちることが非常に少なくなる。また、本実施形態では有機分を含まないため、５００℃以下の高温で使用しても、ガスの発生や炭化あるいは有機分焼失による強度の低下も生じない。そのため、長期に渡って真空劣化しない。
（４）無機バインダ４は、断熱部材６の一部のみの付着であるため、多量の気泡が取り残されることもなく、長期に渡って真空度の低下も生じない。
（５）無機バインダ４は、断熱部材６の一部のみの付着であり、付着量も少なくて済むので、全含浸と比較し、塗布時間及び乾燥時間の短縮化、作業の簡略化、断熱部材６の軽量化等を実現できる。
【００２９】
［第二実施形態］
図２（ｂ）〜（ｆ）は、第二実施形態の真空断熱材７に用いる断熱部材６を示している。真空断熱材７は、第一実施形態と同様、容器５内に断熱部材６を充填するとともに真空排気した状態で、容器周辺部８を封止剤で密封してなるものであるから、図１を援用する。本実施形態の断熱部材６も、容器５の壁が真空排気時に内外の気圧差で凹むのを内側から支えて防ぎ得るように、断熱部材６の一部に無機バインダ４により繊維３の表面及び交点を成膜して強固にした強固部１が設けられている。また、断熱部材６が真空排気時に容器５の壁からの圧縮応力により割れるの防ぎ得るように、断熱部材６の残部は前記無機バインダ４による成膜及び結着の無い（又は相対的に少ない）柔軟部２とされている。しかし、その一部の強固部１と残部の柔軟部２における部位の組合せが、下記の実施例▲５▼〜▲９▼のように、第一実施形態とは一部又は大幅に異なっている。
【００３０】
まず、実施例▲５▼〜▲７▼は、断熱部材６の表面部に強固部１を設けるが、柔軟部２を内部のみならず表面部にも強固部１を分割するように設けて、表面部のたわみ性を大きくし、もって前記縮応力により強固部１に亀裂が生じるのを防ぐようにした態様である。
図２（ｂ）に示す実施例▲５▼は、タイルと目地の関係のように、表面部の強固部１の間に柔軟部２を設けた態様である。
図２（ｃ）に示す実施例▲６▼は、表面部において強固部１と柔軟部２とを縞模様のように交互に配した態様である。
図２（ｄ）に示す実施例▲７▼は、表面部の強固部１の中に複数の柔軟部２を島状に設けた態様である。
【００３１】
次に、実施例▲８▼及び▲９▼は、容器５の壁に接する断熱部材６の表面部及び表面部より内側の内部に強固部１を複数の島状に分散させて設け、断熱部材６の残部を柔軟部２とした態様である。
図２（ｅ）に示す実施例▲８▼は、強固部１を断熱部材６の面方向及び厚さ方向にランダムな位置に島状に分散させて設けた態様である。
図２（ｆ）に示す実施例▲９▼は、断熱部材６の両面間に延びる柱状の強固部１を分散させた態様である。
【００３２】
第二実施形態の断熱部材６も、圧力０．１０ＭＰａで圧縮率１０％以下を保つことができ、第一実施形態と同様の作用効果を発揮する外、前記の通り、第一実施形態の場合よりも表面に亀裂が生じにくい。
【００３３】
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）真空断熱材の容器が袋状になっていて、封止する部分が、断熱部材に対して１辺だけであること。
（２）無機バインダの付着の態様が、１種類の態様の面方向への繰り返しではなく、複数の態様の組み合わせ、例えば図２（ｂ）と（ｆ）を組み合わせた態様であること。
【００３４】
【発明の効果】
以上詳述したように、本発明に係る真空断熱材及びその製造方法によれば、高温使用に適し、十分な耐圧性を有しながら、より軽量で表面の粉っぽさを低減し、繊維の持つ柔軟性を維持しており、断熱性能を長期間維持でき、さらに、比較的容易に製造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】本発明の実施形態を示し、（ａ）は真空断熱材の断面図、（ｂ）はその断熱部材の強固部の拡大模式図である。
【図２】（ａ）は第一実施形態における断熱部材の斜視図、（ｂ）〜（ｆ）は第二実施形態における断熱部材の斜視図である。
【符号の説明】
１強固部
２柔軟部
３セラミック繊維
４無機バインダ
５容器
６断熱部材
７真空断熱材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vacuum heat insulating material and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, as vacuum heat insulating material, needling mats, felts, blankets, etc. made of inorganic fibers are housed in heat insulating containers or bags, then vacuumed and closely adhered, or the whole of inorganic fibers is firmly molded with inorganic binder Then, it is known that it is housed in an insulated container or a bag, and then brought into close contact with a vacuum.
[0003]
[Problems to be solved by the invention]
In the case of a vacuum insulating material in which a needling mat, felt, blanket, etc. made of inorganic fibers are housed in an insulated container or bag and evacuated, the insulated container or bag may be deformed due to uneven density of the mat or felt or compression deformation of the fiber mat. It has the problem of waving or denting. Further, when stored in aluminum foil, when used at high temperatures, there is a problem that heat insulation is impaired by radiation from the aluminum itself.
[0004]
In addition, in the case of a vacuum heat insulating material in which an inorganic fiber formed entirely of an inorganic binder is firmly molded in a heat insulating container or bag and evacuated, there is little dent when evacuated, but the whole is solidified with an inorganic binder. Therefore, it does not have elasticity like unglazed porcelain, cracks occur during evacuation, and the heat insulation performance is reduced. This can be imagined as a structure such as a refractory where brittle fracture easily occurs. In this case, a large amount of inorganic binder is required, and it is difficult to deaerate bubbles inside the molding at the time of evacuation. When used as a vacuum heat insulating material for a long time, the gas generated from the bubbles causes vacuum deterioration. The service life of the insulation performance is shortened. Further, when the container is insulated or evacuated as a heat insulating member and evacuated, if the compression ratio exceeds 10%, there is a problem that the insulated container or sack is remarkably dented by the vacuum force. In this case, in order to reduce the compressibility under a pressure of 0.1 MPa (1.02 kg / cm ² ) to 10% or less, the bulk density needs to be increased, and the thermal conductivity and vacuum degassing properties are reduced. There are points.
[0005]
Furthermore, when an organic binder is used, the pressure resistance and elasticity are superior to those when an inorganic binder is used.However, when the temperature becomes high after vacuum packaging, there is a danger that the organic binder is vaporized, the degree of vacuum is reduced, and the heat insulating performance is deteriorated. There is a problem that it cannot be used at high temperatures.
[0006]
The present invention solves the above-mentioned problems, is suitable for high-temperature use, has sufficient pressure resistance, is lighter, reduces the powderiness of the surface, maintains the flexibility of fibers, and has thermal insulation performance. It is an object of the present invention to provide a vacuum heat insulating material that can be maintained for a long time and that can be manufactured relatively easily.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention employs the following means (1) and (2).
(1) vacuum insulation material of the present invention, in the vacuum heat insulating material formed by sealing the container or bag while evacuating to fill the heat insulating member made of fiber within the container or the bag, the walls or bag of the container Provide a strong part which is made by binding the intersection of fibers mainly by inorganic binder to a part of the heat insulating member so as to be able to support and suppress the depression or deformation due to the pressure difference between inside and outside during evacuation from inside, In order to prevent the heat insulating member from being cracked by the compressive stress from the container wall or the bag at the time of evacuation, the remaining portion of the heat insulating member is a flexible portion having no or relatively little binding. Depending on the type of the “heat insulating member made of fiber” used as the base material, there is a material that already contains an inorganic binder as a whole. The remaining portion may be used as it is to form a flexible portion.
[0008]
(2) the manufacturing method of the vacuum heat insulating material of the present invention is the manufacturing method of the vacuum heat insulating material formed by sealing the container or bag while evacuating to fill the heat insulating member in the container or the bag, container or before filling the heat insulating member in the bag, mainly water-soluble part of the insulating member so that the walls or bag of the container to recessed or deformed pressure difference between the inside and outside at the time of evacuation can be suppressed supported from the inside A heat insulating member is provided so as to prevent the heat insulating member from breaking due to compressive stress from the wall or bag of the container at the time of vacuum evacuation, by providing an inorganic binder to adhere and dry the fiber, thereby binding the intersections of the fibers to provide a strong portion. Is characterized in that the remaining portion is a flexible portion having no or relatively little binding.
[0009]
In the above means (1) and (2), the "container" covers the entire surface of the heat insulating member when it is in a vacuum state, can maintain the vacuum state for a long time, and does not hinder the performance as the heat insulating member. What is necessary is just a thing, and it is not limited to a specific structure, shape, dimension, etc. The material of the container is not particularly limited, and examples thereof include ordinary stainless steel (including copper-plated products), heat-resistant steel, and oxygen-free copper that generates a small amount of gas.
[0010]
The “fiber” is not particularly limited, but is preferably composed mainly of inorganic fibers. Examples of the inorganic fibers include glass fibers, ceramic fibers such as alumina and silica, slag wool fibers, and rock wool fibers. Also, a small amount of heat-resistant metal fiber (fiber such as stainless steel, chromium-nickel alloy, high nickel alloy, high cobalt alloy, etc.) can be mixed. In this case, the heat insulation performance is slightly reduced, but the heat resistance is high. Become. Although the fiber diameter of the fiber is not particularly limited, it is preferably 1 to 30 μm, and depending on the degree of vacuum, the thinner the fiber, the lower the thermal conductivity and the better the heat insulation performance.
[0011]
The term “mainly inorganic binder” means not only a case where only an inorganic binder is used, but also a case where an inorganic binder is used as a main material and an organic binder is added.
[0012]
The “inorganic binder” is not particularly limited as long as it functions as a binder between fibers, and examples thereof include silica sol, alumina sol, titania sol, zirconia sol, water glass, active silica, clay mineral, aluminum biphosphate, and cement. . These inorganic binders may be used as a mixture. Further, although not particularly limited, active silica and aluminum biphosphate have an action of strengthening the bonding force of silica sol and the like, and it is also preferable to use them in a mixed manner. Further, it is preferable to add a ceramic powder.
When ceramic powder is added, powder having low solid thermal conductivity, titania, silicon nitride, and the like are preferable. By adding the ceramic powder, the air gap is reduced and the gas heat conduction is almost eliminated, so that the vacuum insulation performance is improved. However, the number of heat transfer points of the object increases, and the solid heat conduction through which heat is transmitted in the powder increases, so that the vacuum insulation performance deteriorates. Therefore, it is important to adjust the amount of addition that can minimize the contradictory heat conduction under the temperature condition and the vacuum condition used as the vacuum heat insulating material.
[0013]
The "organic binder" is not particularly limited, and examples thereof include starch-based, silicon-based, and rubber-based.
[0014]
“Cracking” means that a crack propagates in the thickness direction of the heat insulating member, and does not include a case where a crack does not propagate in the thickness direction even if a crack is generated on the surface of the heat insulating member.
[0015]
“No binding or relatively little binding” means that binding by the inorganic binder is smaller than that of the strong part. For example, depending on the type of the “insulating member made of fibers” used as the base material, there is a type that already contains an inorganic binder as a whole, but a part of the inorganic binder is additionally added mainly to the inorganic binder. The strong portion may be used, and the remaining portion may be used as it is (with no additional inorganic binder attached) as the flexible portion.
[0016]
Further, the heat insulating member before the adhesion of the inorganic binder is not particularly limited, but preferably has a flexibility with a compression ratio of 10% or more under a pressure of 0.1 MPa (1.02 kg / cm ² ), and after the adhesion. The heat insulating member is not particularly limited, but preferably has a bulk density of 100 to 400 kg / m ³ and a compressibility of 10% or less under a pressure of 0.1 MPa. Further, the thickness of the heat insulating member is not particularly limited, but is preferably 30 to 100 mm. In addition, although not particularly limited, when it adheres to the surface of the heat insulating member, the thickness of the inorganic binder in the strong part is preferably 10 mm or less, and the thickness of the flexible part to which the remaining inorganic binder is not adhered is preferably 20 mm or more.
[0017]
The following modes can be exemplified as combinations of the respective portions in "a part of the heat insulating member ... a strong portion" and "a remaining portion of the heat insulating member ... a flexible portion".
(a) A rigid portion is provided on substantially the entire surface of the heat insulating member in contact with the wall or bag of the container, and the inside of the heat insulating member inside the surface is a flexible portion.
(b) A flexible portion is provided on a part of the surface of the heat insulating member so as to divide the strong portion, thereby preventing a crack from being generated in the strong portion due to compressive stress.
(c) Strong portions are dispersed in a plurality of islands in the surface portion of the heat insulating member in contact with the wall or bag of the container and inside the surface portion, and the remaining portion of the heat insulating member is a flexible portion.
[0018]
As in the above means (1) and (2), a strong portion is formed by binding the intersections of the fibers mainly with an inorganic binder, and the propagation of compressive stress from the inner wall of the container or the bag due to evacuation is diffused. By relaxing, the molded shape is maintained, and even if a crack occurs in the strong part, the crack can be prevented from growing in the flexible part, and the heat insulating member can maintain high toughness.
[0019]
When the inorganic binder is attached, an organic binder may be added and the viscosity may be increased as described above in order to adjust the amount of the inorganic binder attached as necessary. Organic components in the organic binder are vaporized and removed by a heat treatment in a subsequent step. The adhesion method is not particularly limited, and examples thereof include a small amount immersion and impregnation method utilizing the capillary action of the fiber molded body, a brush application, a spray or a sponge roller application method, and the like.
[0020]
The mechanism of the compressive stress from the container inner wall or bag shows a uniform stress distribution according to the principle of Pascal if the inside is a material such as water, but it does not hold in the case of a fiber molded body, and it comes into contact with the inner wall It is transmitted by a fiber and a fiber deformed from each intersection, or a fiber that breaks at an intersection, a fiber that is crushed, or the like. Therefore, by increasing the strength of the fiber or each fiber intersection, the resistance to compression is increased, and the compression ratio can be reduced by spreading the stress with the increase in the number of fiber intersections subjected to internal pressure.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of a vacuum heat insulating material embodying the present invention and a method of manufacturing the same will be described. Note that the materials, configurations, numerical values, and the like described in the embodiments are merely examples, and can be changed as appropriate.
[0022]
[First embodiment]
FIG. 1 shows a vacuum heat insulating material 7 of the first embodiment, and FIG. 2A shows a heat insulating member 6 used for the vacuum heat insulating material 7. The vacuum heat insulating material 7 is obtained by filling a heat insulating member 6 mainly made of ceramic fibers 3 into a stainless steel container 5 and evacuating the container and sealing the container peripheral portion 8 with a sealant. is there. As the material of the heat insulating member 6, a molded flat plate (dimensions: 600 mm × 900 mm × thickness: 50 mm, fiber diameter: 2 to 10 μm, no organic binder) mainly composed of the ceramic fibers 3 is used.
[0023]
In order to prevent the wall of the container 5 from being depressed by the pressure difference between the inside and the outside at the time of evacuation by supporting from the inside, a part of the heat insulating member 6, here substantially the whole of both surface portions of the heat insulating member 6 in contact with the wall of the container 5 Is provided with a solid portion 1 which forms a film on the surface of the fiber 3 by adhering the inorganic binder 4 and binds intersections of the fibers 3 to each other (see FIG. 1B). The adhesion amount (solid content after drying) of the inorganic binder 4 is 100 to 800 g / m ² in Examples (1) to (4) described below, but is not limited to this range. It may be 1000 g / m ² . In order to prevent the heat insulating member 6 from being cracked by the compressive stress from the wall of the container 5 at the time of evacuation, the remaining portion of the heat insulating member 6, here the inside of the heat insulating member 6 inside the surface portion, is formed by the inorganic binder 4. The flexible portion 2 has no (or relatively few) film formation and binding.
[0024]
This vacuum heat insulating material 7 is manufactured by the following method.
(1) Adhesion Step A commercially available water-soluble inorganic binder 4 (NK Bond TA-10 manufactured by New Life Research Institute) is diluted three times with water to substantially the entire surfaces of both surfaces of the molded flat plate of the ceramic fiber 3. It was applied and adhered by a sponge roller.
(2) Drying Step The inorganic binder 4 is dried and hardened under the condition that the formed flat plate of the ceramic fiber 3 to which the inorganic binder 4 has been adhered is kept in a hot air drying oven at 200 ° C. for 30 minutes. Got. The surface portion of the heat insulating member 6 formed the strong part 1 because the dried inorganic binder 4 formed a film on the surface of the fiber 3 and bound the intersection. The remaining part of the heat insulating member 6 became the flexible part 2.
(3) Vacuum Evacuation Step The heat insulating member 6 is filled in a stainless steel container 5, and the peripheral portion 8 is sealed with a sealant in a state of being evacuated (evacuated) to a degree of vacuum of 100 Pa (0.76 Torr). Thus, the vacuum heat insulating material 7 was completed.
[0025]
Examples (1) to (4), which are heat insulating members 6 of the first embodiment, in which the total amount of the inorganic binder 4 (the liquid amount before drying and the solid content after drying) are changed by four points, and the inorganic binder Comparative Example (1), which is an untreated heat insulating member to which No. 4 is not adhered (otherwise the same as in the first embodiment), and the ceramic fiber 3 was completely impregnated with the inorganic binder 4 (otherwise the same as in the first embodiment) Table 1 shows the results of measurement of the bulk density, the compressibility, the thickness dimensional resilience, and the amount of deflection of Comparative Example (2), which is a heat insulating member.
[0026]
[Table 1]

[0027]
As shown in Table 1, in the case of the untreated comparative example (1), since the compression ratio becomes 15.8% at a pressure of 0.10 MPa, there is a problem that when the container is put into the container 5 and evacuated, the container is dented. Occur. In the case of Comparative Example (2) of total impregnation, there is no problem with the compressibility, but since the bulk density increases and is not flexible, cracks and chips generated on the surface extend to the inside, leading to cracks. A problem is the deterioration of the heat insulation performance.
On the other hand, in Examples ( ¹ ) to (4), when the inorganic binder 4 (100 to 800 g / m ² ) is adhered to the molded flat plate of the ceramic fiber 3, the compression ratio is 3.2 at the applied pressure of 0.10 MPa. As can be seen from the dimensional resilience of the thickness, the flexibility of the fiber can be maintained while exhibiting sufficient pressure resistance of up to 4.6%.
[0028]
The operation and effect of the vacuum heat insulating material 7 using the heat insulating member 6 of the first embodiment are as follows.
(1) Due to the presence of the strong part 1 to which the inorganic binder is adhered, it has sufficient pressure resistance, and when the container 5 or the bag is evacuated and evacuated, the heat insulating member 6 compresses and deforms the container 5 or the bag. Depression and deformation can be suppressed.
(2) Even if a crack is generated on the surface (strong part 1) of the heat insulating member 6 due to the compressive force generated by the evacuation, the growth of the crack can be prevented by the internal flexible part 2 and deterioration of the heat insulating performance is prevented. can do.
(3) Since the amount of the inorganic binder 4 to be used is reduced, the powderiness of the surface can be reduced, and when the container 5 is sealed, it is very unlikely that the degree of vacuum is reduced due to incomplete sealing. . Further, in the present embodiment, since no organic component is contained, even when used at a high temperature of 500 ° C. or less, a decrease in strength due to generation of gas or carbonization or burning off of the organic component does not occur. Therefore, there is no vacuum deterioration for a long time.
(4) Since only a part of the heat insulating member 6 is adhered to the inorganic binder 4, a large amount of bubbles are not left, and the degree of vacuum does not decrease over a long period of time.
(5) Since the inorganic binder 4 adheres only to a part of the heat insulating member 6 and requires only a small amount of adhesion, the application time and the drying time can be shortened, the work can be simplified, and the heat insulating member can be compared with the case of full impregnation. 6 can be realized.
[0029]
[Second embodiment]
FIGS. 2B to 2F show the heat insulating member 6 used for the vacuum heat insulating material 7 of the second embodiment. As in the first embodiment, the vacuum heat insulating material 7 is obtained by filling the heat insulating member 6 in the container 5 and evacuating the container 5 and sealing the container peripheral portion 8 with a sealant. Invite. The heat insulating member 6 of the present embodiment also has a part of the heat insulating member 6 with the inorganic binder 4 to prevent the wall of the container 5 from being depressed by the pressure difference between the inside and outside during the evacuation. A strong part 1 is provided which is formed by forming a film at an intersection. In order to prevent the heat insulating member 6 from being cracked by the compressive stress from the wall of the container 5 at the time of evacuation, the remaining heat insulating member 6 has no (or relatively little) film formation and binding by the inorganic binder 4. The flexible portion 2 is provided. However, the combination of the parts of the part of the rigid part 1 and the part of the remaining flexible part 2 is partially or significantly different from the first embodiment as in the following examples (5) to (9). .
[0030]
First, in the embodiments (5) to (7), the rigid part 1 is provided on the surface of the heat insulating member 6, but the flexible part 2 is provided so as to divide the rigid part 1 not only on the inside but also on the surface. This is an embodiment in which the flexibility of the surface portion is increased so that cracking of the strong portion 1 due to the compressive stress is prevented.
Embodiment (5) shown in FIG. 2 (b) is a mode in which a flexible portion 2 is provided between the strong portions 1 on the surface, as in the relationship between tiles and joints.
Embodiment (6) shown in FIG. 2 (c) is a mode in which the strong portions 1 and the flexible portions 2 are alternately arranged like a stripe pattern on the surface portion.
Embodiment (7) shown in FIG. 2 (d) is a mode in which a plurality of flexible portions 2 are provided in the form of islands in the strong portion 1 on the surface.
[0031]
Next, in Embodiments (8) and (9), the rigid part 1 is provided in a plurality of island-like forms in the surface part of the heat insulating member 6 in contact with the wall of the container 5 and inside the surface part. 6 is a mode in which the remaining portion is a flexible portion 2.
Embodiment (8) shown in FIG. 2E is a mode in which the strong parts 1 are provided in an island shape at random positions in the surface direction and the thickness direction of the heat insulating member 6.
Embodiment (9) shown in FIG. 2 (f) is a mode in which the columnar solid portions 1 extending between both surfaces of the heat insulating member 6 are dispersed.
[0032]
The heat insulating member 6 of the second embodiment can also maintain a compression ratio of 10% or less at a pressure of 0.10 MPa and exhibit the same operational effects as the first embodiment. Cracks are less likely to occur on the surface.
[0033]
Note that the present invention is not limited to the configuration of the above-described embodiment, and may be embodied with appropriate modifications without departing from the spirit of the invention, for example, as described below.
(1) The vacuum heat insulating material container has a bag shape, and the portion to be sealed is only one side of the heat insulating member.
(2) The mode of adhesion of the inorganic binder is not a repetition of one type in the plane direction but a combination of a plurality of modes, for example, a mode in which FIGS. 2B and 2F are combined.
[0034]
【The invention's effect】
As described in detail above, according to the vacuum heat insulating material and the method for producing the same according to the present invention, it is suitable for use at high temperatures and has sufficient pressure resistance, while reducing the powderiness of the surface with lighter weight, The excellent effect that the heat insulation performance can be maintained for a long period of time and can be manufactured relatively easily.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention, in which (a) is a cross-sectional view of a vacuum heat insulating material, and (b) is an enlarged schematic view of a rigid portion of the heat insulating member.
FIG. 2A is a perspective view of a heat insulating member according to the first embodiment, and FIGS. 2B to 2F are perspective views of the heat insulating member according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Strong part 2 Flexible part 3 Ceramic fiber 4 Inorganic binder 5 Container 6 Heat insulating member 7 Vacuum heat insulating material

Claims

In the vacuum heat insulating material formed by sealing the container or bag while evacuating to fill the heat insulating member made of a fiber or in the bag container, wall or the bag of the container is recessed in the pressure difference between the inside and outside at the time of vacuum evacuation or In order to be able to support and suppress the deformation from the inside, a part of the heat insulating member is provided with a strong part which is made strong by binding the intersection of the fibers mainly with an inorganic binder, and the heat insulating member is used to evacuate the container wall or A vacuum heat insulating material, characterized in that the remaining heat insulating member is a flexible portion having no or relatively small binding so as to prevent cracking due to compressive stress from the bag .

The vacuum heat insulating material according to claim 1, wherein the fibers are mainly composed of inorganic fibers such as glass fibers, ceramic fibers, slag wool fibers, and rock wool fibers.

The vacuum heat insulating material according to claim 1 or 2, wherein a rigid portion is provided on substantially the entire surface of the heat insulating member in contact with the wall or the bag of the container, and the inside of the heat insulating member inside the surface is a flexible portion.

4. The vacuum heat insulating material according to claim 3, wherein a flexible portion is provided on a part of a surface portion of the heat insulating member so as to divide the strong portion, thereby preventing a crack from being generated in the strong portion due to the compressive stress.

3. The surface part of the heat insulating member in contact with the wall or the bag of the container and a plurality of rigid parts dispersed in a plurality of islands inside the surface part, and the remaining part of the heat insulating member is a flexible part. Vacuum insulation.

The insulating member had a volume density of 100~400kg / ^{m 3,} the vacuum heat insulating material according to any one of claims 1 to 5 compression rate of 10% or less at 0.1MPa pressure.

In the manufacturing method of the vacuum heat insulating material formed by sealing the container or bag while evacuating to fill the heat insulating member within or in the bag container, prior to filling a heat insulating member within or in the bag container, container Water-soluble inorganic binder is mainly attached to a part of the heat insulating member so that the wall or bag can be supported and suppressed from being depressed or deformed due to the pressure difference between inside and outside during evacuation. A strong part is provided by binding the intersections to make it strong, and the remaining part of the heat insulating member has no or relatively little bonding so that the heat insulating member can be prevented from breaking due to compressive stress from the wall or bag of the container during evacuation. A method for producing a vacuum heat insulating material, wherein the method comprises a flexible portion.