JP4273466B2 - Vacuum insulation panel, method for manufacturing the same, and refrigerator using this vacuum insulation panel - Google Patents

Description

【００３８】
硬質ポリウレタンフォームは単体で発泡したときの密度が４５ｋｇ／ｍ³ 、フレーク状マイカは平均直径が１．０ｍｍのものを用いた。硬質ポリウレタンフォームの２液とフレーク状マイカをビーカにとった後、ただちに高速攪拌機にて攪拌を行い、５００Ｌ×３００Ｗ×３０Ｔ（ｍｍ）で４５℃に調温した金型の短辺側に投入した。このとき、金型を完全充填させる必要最低量に対し、１０％の過剰充填量を投入、金型を密封状態にして７分間の静置後、ボード状成型品を得た。芯材にはこのボード状成型品の表面層２．５ｍｍを削除して、さらに１８０×１８０（ｍｍ）の大きさに切断した板を用いた。
【００３９】
また、本発明の比較例として、従来の真空断熱パネルとして特開昭６０−２４３４７１号公報で代表される連通気泡の硬質ポリウレタンフォーム（比較例１）、及び特開昭６２−１３９７９号公報で示された輻射熱の遮蔽効果に優れたアルミ箔を連通気泡の硬質ポリウレタンフォームの薄板の間に配設したもの（比較例２）を、各々芯材に用いた。
比較例１である連通気泡の硬質ポリウレタンフォームは、密度が４５ｋｇ／ｍ³ 、セルサイズが３００μｍのものを用いた。また、比較例２として上記の硬質ポリウレタンフォームを中央部分で切断したものに厚さが１０μｍのアルミ箔を挾み込んだものを、同様の芯材として用いた。
【００４０】
試料とする真空断熱パネルは、上述した各芯材の厚さを２０ｍｍ、面大きさを１８０×１８０ｍｍの大きさに切断、これを１５０℃で１時間程度乾燥した後に使用した。試料とする真空断熱パネルは、１１０℃で３０分乾燥した多層シートで作った包装材内に挿入後、１０⁰ 〜１０^-3Ｔｏｒｒの任意の真空雰囲気中で熱シールすることによって得た。
【００４１】
実施例１〜実施例３の試料に加えて、連通気泡の硬質ポリウレタンフォームの芯材を用いた比較例１、アルミ箔を連通気泡の硬質ポリウレタンフォームの間に挾んだ芯材を用いた比較例２を、各々、熱シールするときの真空度が１０¹ 〜１０^-3Ｔｏｒｒの任意の真空度で調整した真空断熱パネルの同様試料を作製、これら試料の断熱性能の真空依存性に関する評価結果を図６に示す。
表２に、図６の結果より、真空度が１０^-2Ｔｏｒｒ相当のときの断熱性能と５０℃の雰囲気中に最大３０日間放置後の経時変化、さらに変形の評価結果を示した。
【００４２】
【表２】

【００４３】
以上の結果から、硬質ポリウレタンフォームの発泡、流動によってマイカを面方向に配向させた芯材を用いた本発明である真空断熱パネルの断熱性能は、従来の連通気泡の硬質ポリウレタンフォームに比べて、約１０ポイント以上の熱伝導率の低減、つまりの断熱性の向上を達成できた。
さらに、本発明品の経時変化についても、熱伝導率及び変形のいずれとも、比較例１及び比較例２として示した、フレーク状マイカを含まない従来材である連通気泡の硬質ポリウレタンフォームを芯材として用いた真空断熱パネルよりも安定した結果を示していることが確認できた。
【００４４】
実施例Ｂ
次に、本発明の材料組成であるフレーク状マイカの大きさについて述べる。
連続気泡の硬質ポリウレタンフォームに充填するフレーク状のマイカの大きさが異なる材料組成により、実施例Ａと同様の成形方法で作製した芯材及び評価方法を用いて、１０^-2Ｔｏｒｒの真空雰囲気の包装材料内に封入した真空断熱パネルに相当する試料としての断熱性能（初期値および５０℃で１０日間放置した後の経時変化後の値）を評価した。
【００４５】
用いたマイカフレークの平均直径は、表３に示すごとく、連通気泡の硬質ポリウレタンフォームのセルと同一の平均直径である０．１ｍｍからその５０倍以上の７．０ｍｍまで変化させた。
これら平均直径の異なるフレーク状マイカを含有した硬質ポリウレタンフォームを混合、配向させた芯材にに関する断熱性能と１０日間の経時変化後の評価結果を表３に示す。
【００４６】
【表３】

【００４７】
以上の結果から、フレーク状マイカの平均直径が０．２ｍｍ〜４．０ｍｍの各実施例における熱伝導率の差異はほとんどなく、５０℃の雰囲気下で１０日間放置した経時変化後の熱伝導率にも大きな変化がみられず、実用にて支障をきたすこともない。
しかし、比較例３の、直径が０．０５ｍｍのフレーク状マイカを用いた場合には熱伝導率の初期値が大きくなり、逆に、比較例４で示した直径が７ｍｍ以上のフレーク状マイカを用いた場合には、５０℃の雰囲気下で１０日間放置後した経時変化後の熱伝導率に大きな変化がみられ、いずれの場合にも実用に支障をきたす可能性が示唆された。
【００４８】
実施例Ｃ
次に、アルミ箔を板状充填材として用いた場合について述べる。連通気泡の硬質ポリウレタンフォームと平均直径が１．０ｍｍのアルミ箔との複合構造体となるように、実施例Ａと同様の成形方法で作製した芯材および評価方法を用いて、１０^-2Ｔｏｒｒの真空雰囲気の包装材内に封入した真空断熱パネルに相当する試料としての断熱性能（初期値および５０℃で１０日間放置した後の経時変化後の値）を評価した。
【００４９】
表４に、上述した組成の芯材を用いた真空断熱パネルを実施例６として示し、その効果を確認する目的で、板状充填材にフレーク状マイカを用いた実施例２、および連通気泡の硬質ポリウレタンフォームを芯材を用いた比較例１、アルミ箔を連通気泡の硬質ポリウレタンフォームの間に挾んだ芯材を用いた比較例２についても熱伝導率の初期値と５０℃の雰囲気下で１０日間放置後の値を併記した。
【００５０】
【表４】

【００５１】
以上の結果、フレーク状マイカを用いた場合よりもさらに断熱性能の向上が確認され、しかも、比較例で示した連通気泡の硬質ポリウレタンフォームのように、事実上、断熱性能に支障を来すような経時劣化もなく、有効であることが確認された。
【００５２】
実施例Ｄ
次に、硬質ポリウレタンフォームと、それを複合化した板状充填材との離型剤が及ぼす断熱性能の劣化抑制の効果について述べる。
連通気泡の硬質ポリウレタンフォームに表面に離型剤を塗布した平均直径が１．０ｍｍのフレーク状マイカとの複合構造体となるよう、実施例Ａと同様の成形方法で作製した芯材および評価方法を用いて、１０^-2Ｔｏｒｒの真空雰囲気の包装材内に封入した真空断熱パネルに相当する試料としての断熱性能（初期値および５０℃で１０日間放置した後の経時変化後の値）を評価した。
【００５３】
表５に、上述した組成の芯材を用いた真空断熱パネルを実施例６として示し、その効果を確認する目的で、別の離型剤を用いた例を実施例２に示した。
さらに、それら実施例の有効性を確認するために、離型剤を塗布しないフレーク状マイカを用いた例を比較例５に、充填剤を用いない連通気泡の硬質ポリウレタンフォームのみを芯材に用いた比較例１についても、熱伝導率の初期値と５０℃の雰囲気下で１０日間放置した後の値を併記した。
【００５４】
【表５】

【００５５】
以上の結果、離型剤を板状充填材の表面に塗布しなくても、断熱性能の初期値においては、比較例５と比較例１との差異から、連通気泡の硬質ポリウレタンフォームを芯材に用いることよりも遥かに優れた効果が得られることが確認できた。
しかし、経時変化後の数値は実用に支障を来すと予測される程の悪化を示した。これは、連通気泡の硬質ポリウレタンフォームを用いる場合に、完全な連通化が比較例５では不十分であったことから、残存する独立気泡内に二酸化炭素などの発泡ガスがセル外に放出され、これに伴う真空度の低下がもたらす断熱性能の悪化現象であると考えられる。
【００５６】
これに対し、本発明による離型剤をフレーク状マイカの表面に塗布し、それによって発生する硬質ポリウレタンフォームとの剥離が独立気泡の残存をなくするという効果に関し、実施例６および実施例２と比較例５との差異から経時劣化を抑制することが確認できた。
【００５７】
実施例Ｅ
次に、硬質ポリウレタンフォームに投入した板状充填材を配向させることによる断熱性能の向上効果について述べる。板状充填材の配向は、硬質ポリウレタンフォームの発泡速度を早くすることと、金型の厚さ（成型製品の厚さ）に対する流動距離の比（以下、Ｌ／Ｔという）が大きいことによって強くなる。
【００５８】
用いる連通気泡の硬質ポリウレタンフォームの反応速度、およびＬ／Ｔを変えて作製した芯材を用い、これを１０^-2Ｔｏｒｒの真空雰囲気下で包装材内に封入させた真空断熱パネルを試料として断熱性能を評価した。
なお、ここで用いた板状充填材は、平均直径が１．０ｍｍのフレーク状マイカを用い、これと連通気泡の硬質ポリウレタンフォームとの複合構造体を得るため、実施例Ａと同様の成形方法で作製した芯材および評価方法を用いて、１０^-2Ｔｏｒｒの真空雰囲気の包装材内に封入した真空断熱パネルに相当する断熱性能（初期値および５０℃で１０日間放置した後の経時変化後の値）を評価した。
【００５９】
表６に、断熱性能の評価に用いる真空断熱パネルの芯材を成型するときの流動速度の影響について調べた結果を示す。
硬質ポリウレタンフォームが泡立ち初める発泡開始の時間（以下、ＣＴという）から樹脂化に至る時間（以下、ＧＴという）までほぼ一定の速度で発泡流動が進むことから、流動速度の指標となる、ＧＴ−ＣＴ（秒）として示される反応速度を、用いる触媒の量を変えて作製した芯材を実施例２および実施例７、実施例８として組成とともに示した。
【００６０】
【表６】

【００６１】
同様に、表６には、成形に用いた金型（３００Ｗ×５００Ｌ×３０Ｔ）の長さ（流動距離）Ｌを変えて、Ｌ／Ｔの異なる芯材を成形、これを用いて作製した真空断熱パネルの評価結果を、実施例２および実施例７、実施例９、実施例１０として示した。
また、それらの効果を確認する目的で、反応速度を遅くした硬質ポリウレタンフォームから得た芯材を用いた例を比較例６、Ｌ／Ｔの小さな金型から得られた芯材を用いた例を比較例７として示し、熱伝導率の初期値と５０℃の雰囲気下で１０日間放置後の値を、各々併記した。
【００６２】
以上のごとく、実施例２から実施例７さらに実施例８へと反応速度を変化させた場合、断熱性能は明らかに向上の傾向を有することが確認できた。逆に、比較例６で示したように、反応速度が遅い場合には、急激な断熱性能の低下をもたらすことも確認できた。これらの低下の要因については、流動に伴う壁面との速度比から生まれる剪断力を最小限に止めようとすることによってもたらされる板状充填材であるフレーク状マイカの面方向への配向によるものと考えられる。
【００６３】
また、Ｌ／Ｔについても、実施例１０から実施例２、さらに実施例９へと大きくなると、断熱性能が同様に向上する傾向を確認しており、逆に、Ｌ／Ｔが非常に小さい比較例７では断熱性能の悪化傾向を示しており、上述した流動の剪断力による充填材の配向が要因として大いに寄与しているものと考えられる。
【００６４】
断熱性能の経時変化についても、適正な条件下で得られた各実施例では１〜３ポイントの変化に止まる結果が得られたが、比較例で示した剪断のかかりにくい流動形態をとった場合には７〜９ポイントもの悪化をもたらした。
これも、本来、厚さ方向の配向にかかる板状充填材との剥離が連続性をもたらしやすい亀裂を得るものであるのに対して、不十分な配向状態では非連続となって発泡ガスが残存しやすい状況を生み、それらのガスの漏洩から真空度の低下が断熱性能の悪化をもたらす結果を招いたものと考えられる。
【００６５】
実施例Ｆ
次に、発泡成型品の表面層削除による断熱性能の安定性向上効果について述べる。硬質ポリウレタンフォームの最表面には樹脂の薄皮層が存在し、さらにその下には高密度なスキン層を有した後、コア層と呼ばれる均質で安定した品質を有するコア層がある。このうち、スキン層までは金型との流動抵抗が大きく、金型内を流動せずにコア層との界面で割れて、金型面にほとんど滞留した結果として生成される高密度な層である。従って、スキン層までの表面層には流動に伴う泡同士または板状充填材との間で剪断力が働かず、独立気泡が多く残存することが考えられる。
【００６６】
板状充填材を含有する連通気泡硬質ポリウレタンフォームの成型品を実施例Ａと同様の成形方法で作製した芯材および評価方法を用いて、１０^-2Ｔｏｒｒの真空雰囲気の包装材内に封入した真空断熱パネルに相当する断熱性能（初期値および５０℃で１０日間放置した後の経時変化後の値）を評価した。
なお、ここで表面層から任意の厚さを均一に削除した芯材を作製して用い、板状充填材には平均直径が１．０ｍｍのフレーク状マイカを用いて、これと連通気泡の硬質ポリウレタンフォームとの複合構造体を得た。
【００６７】
表７に、断熱性能を評価する真空断熱パネルに用いた芯材の組成と、その芯材を得るために板状成型品の表面層を削除する量について、実施例２および実施例１１、実施例１２として示した。
成形に用いた金型（３００Ｗ×５００Ｌ×３０Ｔ）の長さＬと厚さＴを変えてＬ／Ｔを一定（１６．６）としたうえで、厚さＴを２５ｍｍ、３０ｍｍ、４０ｍｍの板状成型品を作製し、これから表裏各２．５ｍｍ、５．０ｍｍ、１０．０ｍｍを削除して２０ｍｍ厚の芯材を成形した。真空断熱パネルはこれら表面削除量の異なる芯材を用いて作製し、その熱伝導率の評価結果を、実施例２および実施例１１、実施例１２に示した。
【００６８】
【表７】

【００６９】
また、この表面層の削除による熱伝導率の安定確保を確認する目的で、表面層を削除しない例を比較例８に、削除する量を少なくした例を比較例９に、各々板状成型品のＬ／Ｔを一定とした上記と同様の方法で得た芯材を用いた真空断熱パネルについて、熱伝導率の初期値と５０℃の雰囲気下で１０日間放置後の値を併記した。
【００７０】
以上の結果、実施例２、１１、１２の断熱性能にはほとんど差異がなく、かつ経時変化もきわめて少ない安定した結果が得られた。
これに対し、比較例で示した表面層の削除量が少ない場合には、断熱性能の初期値には実施例との間で差異がない反面、経時変化については表面層を削除する量に応じて悪化の生じることが確認できた。表面層を削除する量に応じて経時変化が抑制でき、削除しない場合の悪化量が最も大きい傾向を有する。比較例における削除量では、実用に耐えうることが不可能であるといえる。
【００７１】
実施例Ｇ
次に、本発明に係る真空断熱パネルを用いた冷蔵庫の運転性能を測定し、その効果を確認した。
まず、アルミ箔を中間層に有する包装材を用いて実施例Ａに示す実施例１と同じ方法で作製した真空断熱パネルを用い、薄板鋼板の折り曲げ加工によって得られた外箱８にＡＢＳ樹脂の真空成型によって得られた内箱９を嵌合して形成された空間に、図５に示すごとく、外箱８側に真空断熱パネル７を貼り付けて配設した。この状態で、図６に示すように、残りの空間に硬質ポリウレタンフォーム１０を注入、発泡させ充填することで完全固定させた。
【００７２】
上記方法で作製した断熱箱体を用いて組み立てた４００Ｌクラスの冷蔵庫を実施例１３とした。
一方、実施例Ａに示す比較例１と同じ方法で作製した芯材を連通気泡の硬質ポリウレタンフォームを芯材とした真空断熱パネルを用いて同様に作製した断熱箱体を用いた冷蔵庫を比較例１０、内箱と外箱の間隙のすべてを硬質ポリウレタンフォームで充填した断熱箱体を比較例１１とし、これらすべての冷蔵庫をＪＩＳ９６０７における消費電力Ｂ法測定法に準拠して消費電力を求め、表８に併記した。
【００７３】
【表８】

【００７４】
以上の結果から、本発明の真空断熱パネルを用いた冷蔵庫の消費電力量は、硬質ポリウレタンフォームのみを断熱材として用いた比較例１１の従来の冷蔵庫に比較して少なく、箱体の断熱性能が有為に優れていることが解った。しかも、同様の真空断熱パネルを断熱材の一部に用いた冷蔵庫と比較しても、連通気泡の硬質ポリウレタンフォームが芯材である従来仕様の真空断熱パネルを用いた比較例１０の冷蔵庫より、消費電力量が少ない冷蔵庫を得られることも確認できた。
【００７５】
以上、本発明の実施の形態である冷蔵庫について説明したが、本発明はこれに限定されるものではなく、例えば、車載用小型冷蔵庫やプレハブ式簡易冷蔵庫、保冷車やパイプや建築物の保温材など、保温および保冷用製品の断熱用部品としての応用も可能であり、その要旨を脱し得ない範囲で種々変形して実施することができる。
【００７６】
【発明の効果】
以上の説明から明らかなように、本発明によれば、次のような効果を得ることができる。なお、説明に当たっては、請求項の番号と同じ番号を付してそれぞれの請求項の効果を記述する。
【００７７】
（１） 本発明にかかる真空断熱パネルは、芯材によって形状を保持してなる真空断熱パネルであって、芯材を、離型性が付与された粉砕片または切断片の板状充填材を含有する連通気泡の硬質ポリウレタンフォームからなる多孔体で構成し、板状充填材の面を芯材の面方向と平行に配向させたので、真空状態のパネル形状を保持することができ、熱伝達と輻射伝達の量を抑制でき、断熱性も大きい。また、板状充填材の表面に離型剤を塗布したので、ウレタン樹脂と板状充填材が剥離する際にセルの連通化がより確実に達成され、また、より確実に貫通される。しかも、その剥離が新たな空隙を形成して真空中での熱の伝搬を妨げる効果も生み、飛躍的に断熱性が向上する。また、板状充填材の面が熱の貫通方向と直交する方向に配向され、輻射熱の遮蔽効果向上による優れた断熱性能とその経時安定性を確保することができる。
【００７８】
（２） 上記（１）の板状充填材に無機物または金属の少なくとも一方を用いたので、輻射熱を反射し易く、その遮断効果によって断熱性が向上する。
（３） 上記（２）の板状充填材にフレーク状マイカを用いたので、輻射熱を反射し易く、その遮蔽効果によって断熱性が向上する。
【００７９】
（４） 上記（２）の板状充填材にプラスチックスフィルムを用いので、輻射熱を反射し易く、その遮蔽効果によって断熱性が向上する。
（５） 上記（２）の板状充填材に金属薄膜を被覆したプラスチックスフィルムを用いたので、輻射熱を反射しやすく、その遮蔽効果によって断熱性が向上する。
【００８０】
（６） 上記（２）の板状充填材に金属箔を用いたので、輻射熱を反射しやすく、その遮蔽効果によって断熱性が向上する。
（７） 上記（５），（６）の金属薄膜または金属箔にアルミニウムを用いたので、輻射熱を反射しやすく、その遮蔽効果によって断熱性が向上する。
【００８１】
（８） 上記（１），（２），（３），（４），（５），（６）又は（７）の板状充填材の大きさを硬質ポリウレタンフォームのセルサイズよりも大きくしたので、セルの連通化を効率よく促進させることができる。
（９） 上記（１）の芯材の表面層を削除したので、輻射熱の遮蔽効果が向上して、優れた断熱性能と経時安定性を確保することができる。
【００８２】
（１０） 本発明による真空断熱パネルの製造方法は、板状充填材の表面に離型剤を塗布し、板状充填材と硬質ポリウレタンフォームとの原料液を混合して板状成型型の端部から注入し、端部から発泡させて流れ方向にシェアをかけ、板状充填材の面を板状成型品の面方向と平行に配向させ、得られた成型品の表面層を削除したので、板状充填材を伝熱方向と直角に配向でき、輻射伝熱の遮断により一層の断熱性向上が可能となる。板状充填材の表面に離型剤を塗布したので、ウレタン樹脂と板状充填材が剥離する際にセルの連通化がより確実に達成され、また、より確実に貫通される。芯材の表面層を削除したので、輻射熱の遮蔽効果が向上して、優れた断熱性能と経時安定性を確保することができる。
【００８３】
（１１） 上記（１０）の板状充填材を硬質ポリウレタンフォームの原料液であるプレミックス液とイソシアネート液を混合する直前に投入し、これらの混合原料を発泡に間に合うように板状成型型の端部から注入し、この端部から発泡させてその後の発泡により流れ方向にシェアをかけ、板状充填材の面を板状成型品の面方向と平行に配向させるようにしたので、板状充填材を伝熱方向と直角に配向でき、輻射伝熱の遮断により一層の断熱性向上が可能となる。また、製造時の取扱いが容易で、量産性に優れる。
【００８４】
（１２） 上記（１０），（１１）の板状充填材の大きさを硬質ポリウレタンフォームのセルサイズよりも大きくしたので、セルの連通化を効率よく促進させることができる。
（１３） 上記（１０），（１１）又は（１２）の発泡液の流動距離Ｌに対する成型品厚さＴの比率Ｌ／Ｔを、１０以上にしたので、断熱性能を大幅に向上させることができる。
【００８５】
（１４） 本発明にかかる冷蔵庫は、（１），（２），（３），（４），（５），（６），（７），（８），（９）のいずれかに記載の真空断熱パネルを内箱と外箱の間に配設したので、断熱性が増して消費電力の低減が達成できる。
【００８６】
（１５） 上記（１４）の真空断熱パネルを内箱又は外箱に貼り付け、残った空間に硬質ポリウレタンフォームを充填したので、上記（１４）の効果と共に外箱と内箱を完全に固定でき、また従来の構造仕様を変更する必要もない。
【図面の簡単な説明】
【図１】 真空断熱パネルの製造工程を示す説明図である。
【図２】 真空断熱パネル製造装置を示す側面図である。
【図３】 真空断熱パネルを用いた製品組立工程を示す説明図である。
【図４】 真空断熱パネルを組込んだ製品の斜視図である。
【図５】 図４の要部の縦断面図である。
【図６】 断熱性能の真空度依存性を示す線図である。
【図７】 各断熱材の断熱性能を比較した説明図である。
【符号の説明】
２ 芯材、７ 真空断熱パネル、８ 外箱、９ 内箱、１０ 硬質ポリウレタンフォーム。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum heat insulating panel used as a heat insulating material in a gap constituted by a thin metal plate and a resin molded product on a wall surface requiring heat insulation, such as a refrigerator or a cold car, and more specifically, an outer shell. The inside of a container or packaging made of an air-impermeable film such as aluminum foil, etc. The vacuum heat insulation panel provided with the core which has the function to hold | maintain, its manufacturing method, and the refrigerator using this vacuum heat insulation panel.
[0002]
[Prior art]
Conventionally, the wall surface of a heat insulator used for a refrigerator or a cold car is covered with a thin metal plate such as an iron plate and the inner surface portion is formed of a resin molded product, and a rigid polyurethane foam is injected and foamed into the gap. Things have been used.
1,1-dichloro-1-fluoroethane, which is a hydrochlorofluorocarbon, has been used as a foaming agent for rigid urethane foam, which is a heat insulating material, but it recently contains chlorine that causes ozone layer destruction in the molecule. It has been proposed to use non-hydrofluorocarbons and hydrocarbons.
[0003]
For example, in JP-A-2-235882, 1,1,2,2,3-pentafluoropropane (HFC-245fa) and 1,1,1,4,4,4-hexafluorobutane (HFC-356mffm) are disclosed. JP-A-3-152160 discloses a method for producing a rigid polyurethane foam in which a hydrocarbon such as cyclopentane is applied to a foaming agent.
However, the heat insulation of these rigid polyurethane foams is 19 to 20 mw / mk, which is evident when compared with the heat insulation of 16 mw / mk when using chlorofluorocarbons used before the regulation of ozone-depleting substances. Inferior to
[0004]
For this reason, as shown in FIG. 7 which compares the performance of each heat insulating material, the technique which applies the vacuum heat insulation panel which can obtain the heat insulation performance more than twice the vacuum heat insulation panel comprised with the conventional rigid polyurethane foam is proposed. Yes. For example, Japanese Patent Laid-Open No. 60-243471 discloses a heat insulating box body in which a pulverized product of rigid polyurethane foam (hereinafter referred to as PUF) is placed in a synthetic resin bag and vacuum-packed into a board is disposed in a wall. Japanese Patent Laid-Open No. 60-60483 discloses a method for installing a vacuum heat insulation panel in which a gap through which PUF flows is provided on the flange side of the side plate.
The core material of such a vacuum heat insulation panel has a strength equal to or higher than atmospheric pressure, and it is necessary to suppress the amount of heat conduction and radiant heat transfer. Therefore, the core material is a substance having a small heat transfer amount. A porous plate made of porous material is used.
[0005]
[Problems to be solved by the invention]
As satisfying the above conditions, open-celled rigid polyurethane foam is disclosed in JP-A-60-205164, pearlite powder is disclosed in JP-A-60-71881, and thermoplastic urethane is disclosed in JP-A-4-218540. Vacuum insulation is used for plate-like molded products obtained by sintering resin powder in a mold, and in Japanese Patent Application Laid-Open No. 7-96580, a board in which glass long fibers are solidified and held by fibrillated resin fibers. Used as a core material for panels. However, in these methods, since the heat insulation mechanism necessary for the core material of the vacuum heat insulation panel is applied only to a part, the thermal conductivity as the vacuum heat insulation panel is insufficient.
[0006]
For this reason, in order to achieve the improvement of the heat insulation performance, Japanese Patent Application Laid-Open No. Sho 62-13979 in which a metal foil or a metal vapor deposition film excellent in shielding effect of radiant heat is embedded, or a PUF mixed with fine powders such as calcium silicate is used. There is an invention disclosed in Japanese Patent Laid-Open No. 63-135694 used.
[0007]
However, a considerable amount is required to mix particulate substances such as calcium silicate, and the heat conductivity of these fillers is high, so that sufficient heat insulation has not been obtained. Moreover, even if the core material is provided with a metal foil, the heat transfer does not attenuate only by spreading in the surface direction, and therefore, the structure has not been obtained to suppress the heat transfer between substances.
In addition, if the PUF pulverized product described in JP-A-60-243471 is used as it is, the volume of the bag after insertion into a vacuum heat insulating panel or after the packaging bag is evacuated greatly decreases. There are difficulties.
[0008]
The present invention has been made to solve the above-described problems, can be produced without causing environmental destruction, can maintain a vacuum panel shape, can suppress the amount of heat transfer and radiant heat transfer, lightweight An object of the present invention is to provide a vacuum heat insulating panel having a high heat insulating property, excellent in mass production, excellent in handling at the time of manufacture, a manufacturing method thereof, and a refrigerator using this vacuum heat insulating panel.
[0009]
[Means for Solving the Problems]
  (1) The vacuum heat insulation panel according to the present invention maintains the shape by the core material.do itIt is a vacuum insulation panel that consists of a core material,Of crushed pieces or cut pieces with releasabilityConsists of a porous body made of open-cell rigid polyurethane foam containing a plate-like fillerThen, the surface of the plate-like filler was oriented parallel to the surface direction of the core materialIs.
[0010]
  (2) the above(1)In the vacuum insulation panel described, at least one of an inorganic material and a metal was used for the plate-like filler.
  (3) the above(2)In the vacuum insulation panel described, flaky mica was used as the plate-like filler.
  (4) the above(2)In the vacuum insulation panel described, a plastic film was used as the plate-like filler.
[0011]
  (5) the above(2)In the vacuum insulation panel described, a plastic film in which a metal thin film was coated on a plate-like filler was used.
  (6) the above(2)In the described vacuum heat insulating panel, a metal foil was used for the plate-like filler.
  (7) the above(5), (6)In the vacuum insulation panel described, aluminum was used for the metal thin film or metal foil.
[0012]
  (8) Above (1), (2), (3), (4), (5), (6),(7) NotesIn the vacuum insulation panel described above, the size of the plate-like filler was made larger than the cell size of the rigid polyurethane foam.
  (9) the above(1) NotesIn the vacuum insulation panel described above, the surface layer of the core material was deleted.
[0013]
  (10The manufacturing method of the vacuum heat insulation panel by this invention is a plate-shaped filler.Apply release agent to the surface of the plate and fill it with plateAnd rigid polyurethane foamWithThe raw material liquid is mixed and injected from the end of the plate-shaped mold, and foamed from this end, sheared in the flow direction, and the surface of the plate-shaped filler is oriented parallel to the surface direction of the plate-shaped molded product.Removed the surface layer of the resulting molded productIs.
[0014]
  (11) the above(10)In the vacuum insulation panel manufacturing method described above, the plate-like filler is introduced immediately before mixing the premix liquid and the isocyanate liquid, which are the raw liquids of rigid polyurethane foam, and the mixed raw materials are formed into a plate shape in time for foaming. It is injected from the end of the mold, foamed from this end, and then sheared in the flow direction by subsequent foaming so that the surface of the plate-like filler is oriented parallel to the surface direction of the plate-like molded product is there.
[0015]
  (12) In the vacuum heat insulating panels described in (10) and (11) above, the size of the plate-like filler is made larger than the cell size of the rigid polyurethane foam.
  (13) Above (10), (11), (12)RecordIn the method for manufacturing a vacuum insulation panel described above, the ratio L / T of the molded product thickness T to the flow distance L of the foaming liquid was set to 10 or more.
[0016]
  (14The refrigerator according to the present invention is a vacuum according to any one of (1), (2), (3), (4), (5), (6), (7), (8), (9). An insulating panel is disposed between the inner box and the outer box.
  (15Also, above(14)In the refrigerator, a vacuum heat insulation panel was attached to the inner box or the outer box, and the remaining space was filled with rigid polyurethane foam.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
In order to improve thermal insulation performance, use materials with low thermal conductivity for the constituent materials, reduce the contact area between materials, and control the heat transfer through the materials in the plane direction perpendicular to the thermal insulation direction (thickness) It is necessary to provide a heat insulation mechanism that suppresses the amount of heat transfer in the direction of the material, and further mixes a substance having a high heat reflection capability to reduce the amount of heat transfer due to radiation.
[0018]
In the present invention, the rigid polyurethane foam is mixed with an inorganic material such as mica, which has an excellent shielding effect against radiant heat, and a plate-like filler having a high density and excellent heat reflectivity, such as a metal foil such as aluminum. A molded product obtained by foam molding so as to flow inside is used as a core material of a vacuum heat insulating panel.
Moreover, in order to eliminate the closed cells of the molded product, in addition to using the conventional rigid polyurethane foam having open cells, a release agent is applied to the plate-like filler.
[0019]
The heat insulation performance is improved by using the open-celled rigid polyurethane foam mixed with the plate-like filler configured as described above as the core material of the vacuum heat insulation panel. The mechanism is considered as follows. That is, the plate-like filler excellent in the radiant heat shielding effect flows in the mold as the rigid polyurethane foam is foamed and expanded while maintaining the mixed state with the foamed liquid of the rigid polyurethane foam.
[0020]
At this time, the plate-like filler is oriented in the flow direction, that is, the surface direction, which is difficult to receive the shearing force generated by the flow velocity difference based on the flow resistance received on the mold surface. Even though the heat transfer coefficient of the plate-like filler is larger than that of the rigid polyurethane foam, it is not oriented in continuous contact with the heat insulation direction by orienting in the plane direction perpendicular to the heat insulation direction. Since it is a very thin substance, the heat insulation effect due to heat transfer in the thickness direction does not deteriorate significantly. Moreover, since the plate-like filler is a flake-like piece, it is not continuous in the lateral direction, and the amount of heat transfer does not attenuate and spread.
[0021]
Therefore, compared to the case where only the conventional open-celled rigid polyurethane foam is used as the core material, the increase in the amount of heat transferred through the substance is negligible, and the decrease in the amount of radiant heat transfer exceeds that, It is considered that the heat insulation performance of the filled heat insulator can be improved.
Furthermore, since it is a composite in which plate-like fillers are arranged in the plane direction on rigid polyurethane foam, the core material in the vacuum heat insulation panel can sufficiently secure compressive strength exceeding the atmospheric pressure that the core material receives under vacuum. Will not be deformed by the atmospheric pressure received when the packaging material is evacuated.
[0022]
On the other hand, in order to maintain the vacuum state inside the core material, in order to prevent deterioration of the heat insulation performance due to the remaining closed cells releasing the internal gas and lowering the degree of vacuum in the system, rigid polyurethane foam is used. It is necessary to consider that the individual bubbles having a size of 100 to 200 μm, that is, the film existing at the boundary of the cell is broken and communicated. As a countermeasure, the plate-like filler is made larger than the cell size, that is, the cell size, and the release agent is applied, so that the stress caused by the shrinkage when the rigid polyurethane foam is converted to resin is in the surface direction. The function achieved by creating a new void while destroying the penetrating cell film at the time of peeling from the plate-like filler disposed in the plate is added.
[0023]
FIG. 1 is an explanatory view showing an outline of a manufacturing process of a vacuum heat insulating panel. As shown in the figure, first, a plate-like filler A prepared by pulverizing mica or cutting an aluminum foil, a premix solution B prepared from a polyol solution, a catalyst, a communicating material, a foaming agent, and the like, and an isocyanate solution C is mixed (step S-1), and these are put into a mold to perform molding (step S-2). Next, the surface layer of the molded product is deleted (step S-3), and the outer periphery is cut (step S-4).
[0024]
And this is inserted in a packaging material (step S-5), and vacuum drawing (step S-6) and end piece welding (step S-7) are taken out by a vacuum panel molding machine (step S-8). .
The manufacturing process of the vacuum insulation panel as described above is further performed by (1) creating a core material (step S-1 to step S-4) and (2) creating a vacuum insulation panel (step S-5 to step S-). 8) and will be described in detail.
[0025]
(1) Creation of core material (step S-1 to step S-4)
First, a method for producing the core material will be described in detail by taking as an example a core material obtained by combining hard polyurethane foam and mica, which is a plate-like filler, into a board shape.
(A) Adjustment of plate-like filler A
The plate-like filler needs to be excellent in heat reflectivity, and a high-density substance such as an inorganic substance or a metal is preferable. In view of the price reflected from the ease of plate-like piece formation, it is most preferable to use aluminum foil or mica. The same effect can be obtained even when a plastic film, which is a low-density material, is used with a metal film such as aluminum coated on the surface.
[0026]
Here, a case where mica is used in the form of flakes will be described. Since the flake-like mica has a cell size of rigid polyurethane foam of 70 μm to 200 μm, it has a diameter of 0.1 mm or more, preferably 5 mm to 0.1 mm, more preferably 2 mm to 0.5 mm by pulverization. Smash.
If a high-speed water flow by a water jet is applied to the pulverization at this time, peeling between layers is performed at the same time, and a thinner flake-like mica is obtained.
These plate-like fillers are sprayed with a 1% to 10% solution of a release agent such as paraffin or silicone, or the surface is covered by a method such as charging or dipping, and then the solvent is removed by hot air drying. Then, use what was applied.
[0027]
(B) Preparation and foam molding of rigid polyurethane foam raw material liquids B and C (step S-1 to step S-2)
The rigid polyurethane foam raw material liquid has two liquids, a premix liquid in which a catalyst, a foam stabilizer, a foam breaker, a foaming agent and the like are mixed, and an isocyanate liquid mainly composed of isocyanate, mainly in a polyol. Foaming is initiated by mixing each defined amount. An arbitrary amount of the plate-like filler coated with the release agent is added immediately before mixing them.
[0028]
These raw materials are mixed using an impeller-type mixer, and put into a mold in time for foaming started after a few seconds. The mold temperature at this time is preferably 30 ° C to 60 ° C, and particularly preferably 40 ° C to 50 ° C.
A preferred ratio (L / T) of the molded product thickness T to the flow distance L of the foaming liquid used is 10 or more, and particularly preferably 20 to 40.
The flow distance L is preferably 1000 mm or less in order to obtain a homogeneous molded product.
[0029]
Specifically, the size of the mold used for carrying out the following examples was width (W): 300 mm, flow distance (L): 500 mm, and molded product thickness (T): 30 mm.
The mixed solution is filled with the raw material so that the liquid is accumulated only at the end where the mold is inclined at 45 degrees. Immediately after the addition, the mold is sealed and allowed to stand, and after standing for 5 minutes or more, it is molded into a board shape. The product was secured.
[0030]
(C) Preparation of core material (step S-3 to step S-4)
The obtained molded product may be used as it is as a core material, but preferably, not only the shearing force applied to the surface portion in contact with the mold is insufficient, but the orientation of the plate filler is insufficient, and closed cells Many of them remain, and are deleted by cutting them. The thickness to be deleted is preferably 2 mm or more, and particularly preferably 5 mm or more. Further, the outer periphery is cut to obtain a predetermined size.
[0031]
(2) Creation of vacuum insulation panel (Step S-5 to Step S-8)
The core material is obtained by storing the core material in a packaging material of a multilayer sheet, and then thermally welding the insertion opening in a vacuum atmosphere. Below, the formation method of a vacuum heat insulation panel is described.
The core material is cut and adjusted to obtain a predetermined surface size. Samples used for various evaluations centering on heat insulation are inserted into the packaging material that has been heat-sealed in three directions in advance and then loaded into the apparatus shown in FIG. 2 to ensure an atmosphere of a predetermined degree of vacuum. The remaining one direction was heat-sealed. The degree of vacuum is 1 × 10¹-10^-3Any value between Torr.
[0032]
That is, as shown in FIG. 2, after the core material 2 inserted in the packaging material 1 is mounted between the upper and lower fusion heaters 3 and 3, the inside of the vacuum panel molding machine 4 is kept at a predetermined degree of vacuum. It adjusts with the valve 5 for vacuum adjustment so that it may become. Thereafter, the insertion port is fixed using the sealing pressurizing devices 6 and 6, heat-sealed, the heater is turned off, the vacuum is released after cooling, and the vacuum heat insulating panel 7 is obtained.
[0033]
The packaging material 1 used here is a thermoplastic resin whose sealing surface can be heat-welded, an intermediate layer is resistant to metal foil such as aluminum foil for completely blocking the intrusion of outside air, and the outermost layer is resistant to scratches, etc. A multilayer sheet using a resin such as nylon or polyester.
The core material 2 has a thickness of 20 mm and a surface of 180 × 180 mm. Further, the core material 2 and the packaging material 1 were used after being dried at a temperature of 100 ° C. or higher.
[0034]
FIG. 3 is an explanatory view showing an outline of a process for assembling a product (in this case, a refrigerator) using a vacuum heat insulating panel, and FIGS. 4 and 5 are perspective views showing the usage state of the assembled product and a longitudinal section of its main part a. FIG. As shown in the figure, after attaching the vacuum heat insulation panel 7 to the outer box 8 (step S-1), the inner box 9 is inserted into the fitting portion of the outer box 8 (step S-2), and combined. The assembly of the box including the other members is completed (step S-3). Next, the heat insulation layer 10 is formed by inject | pouring the raw material liquid mixture of a rigid polyurethane foam into the space part formed between the outer box 8 and the inner box 9, and making it foam-mold (step S-4). Thereafter, the internal parts and refrigerant circuit parts are used to arrange the internal parts and assemble the product of the refrigerant circuit (step S-5). When the product inspection is completed (step S-6), the product is completed (step S). -7).
[0035]
Evaluation of the core material obtained as described above and incorporated in the product was performed with respect to the heat insulation performance and its change over time, and the change over time of the shape using the obtained vacuum heat insulation panel (shown below, Examples AG).
The thermal insulation performance was evaluated by thermal conductivity, and “Auto Lambda” manufactured by Eihiro Seiki Co., Ltd. was used for the measurement. Further, the temporal change in the heat insulation performance was evaluated by determining the thermal conductivity after leaving the vacuum heat insulation panel in an atmosphere of 50 ° C. for an arbitrary time, and the change immediately after the preparation of the sample.
As for the change with time of the shape, visual observation was performed on the deformation of the side portion where the contraction was particularly easy to distinguish.
[0036]
Example A
Below, confirmation of the improvement effect of heat insulation performance is described.
First, Table 1 shows the compositions of the core materials used as samples in Examples 1 to 3 of the present invention.
[0037]
[Table 1]

[0038]
Rigid polyurethane foam has a density of 45kg / m when foamed alone.^ThreeThe flake mica having an average diameter of 1.0 mm was used. After taking 2 liquids of hard polyurethane foam and flake-like mica into a beaker, the mixture was immediately stirred with a high-speed stirrer and charged into the short side of the mold adjusted to 45 ° C. with 500 L × 300 W × 30 T (mm). . At this time, an excess filling amount of 10% with respect to the minimum required amount for completely filling the mold was charged, and the mold was sealed, and left standing for 7 minutes to obtain a board-shaped molded product. As the core material, a board obtained by deleting the surface layer of 2.5 mm from the board-like molded product and further cutting it into a size of 180 × 180 (mm) was used.
[0039]
As comparative examples of the present invention, open-cell rigid polyurethane foams represented by JP-A-60-243471 (Comparative Example 1) and conventional JP-A-62-213979 are shown as conventional vacuum insulation panels. The aluminum foil excellent in the shielding effect of radiant heat arranged between thin plates of open-celled rigid polyurethane foam (Comparative Example 2) was used as the core material.
The open cell rigid polyurethane foam of Comparative Example 1 has a density of 45 kg / m.^ThreeA cell size of 300 μm was used. Further, as Comparative Example 2, a material obtained by slicing an aluminum foil having a thickness of 10 μm into the hard polyurethane foam cut at the center portion was used as a similar core material.
[0040]
The vacuum heat insulation panel used as a sample was used after the thickness of each of the above-described core members was cut to 20 mm and the surface size was 180 × 180 mm and dried at 150 ° C. for about 1 hour. The vacuum insulation panel used as a sample is inserted into a packaging material made of a multilayer sheet dried at 110 ° C. for 30 minutes.⁰-10^-3Obtained by heat sealing in any vacuum atmosphere of Torr.
[0041]
In addition to the samples of Examples 1 to 3, Comparative Example 1 using an open-celled rigid polyurethane foam core, Comparison using an aluminum foil sandwiched between open-celled hard polyurethane foams In Example 2, the degree of vacuum when heat-sealing is 10¹-10^-3The same sample of the vacuum heat insulation panel adjusted with the arbitrary degree of vacuum of Torr was produced, and the evaluation result regarding the vacuum dependence of the heat insulation performance of these samples is shown in FIG.
Table 2 shows that the degree of vacuum is 10 based on the result of FIG.^-2The thermal insulation performance at the time equivalent to Torr, the change with time after standing in a 50 ° C. atmosphere for a maximum of 30 days, and the evaluation results of deformation were shown.
[0042]
[Table 2]

[0043]
From the above results, the heat insulation performance of the vacuum heat insulation panel according to the present invention using the core material in which the mica is oriented in the plane direction by foaming and flow of the rigid polyurethane foam, compared with the conventional open cell rigid polyurethane foam, The thermal conductivity was reduced by about 10 points or more, that is, the heat insulating property was improved.
Furthermore, regarding the time-dependent change of the product of the present invention, the open-celled rigid polyurethane foam, which is a conventional material that does not contain flake-like mica, is shown as Comparative Example 1 and Comparative Example 2 for both the thermal conductivity and deformation. It was confirmed that the results were more stable than those of the vacuum insulation panel used.
[0044]
Example B
Next, the size of the flake mica which is the material composition of the present invention will be described.
Using a core material produced by the same molding method as in Example A and an evaluation method using a material composition having different sizes of flake-like mica filled in open-cell rigid polyurethane foam, 10^-2The thermal insulation performance (initial value and value after aging after standing at 50 ° C. for 10 days) as a sample corresponding to a vacuum thermal insulation panel enclosed in a packaging material in a vacuum atmosphere of Torr was evaluated.
[0045]
As shown in Table 3, the average diameter of the mica flake used was changed from 0.1 mm, which is the same as the cell of the open-celled rigid polyurethane foam, to 7.0 mm, which is 50 times or more.
Table 3 shows the heat insulation performance of the core material mixed and oriented with these hard polyurethane foams containing flaky mica having different average diameters and the evaluation results after 10 days of change.
[0046]
[Table 3]

[0047]
From the above results, there is almost no difference in thermal conductivity in each Example in which the average diameter of flaky mica is 0.2 mm to 4.0 mm, and the thermal conductivity after change with time in a 50 ° C. atmosphere for 10 days. However, there is no major change, and there is no problem in practical use.
However, when the flaky mica having a diameter of 0.05 mm of Comparative Example 3 is used, the initial value of the thermal conductivity is increased, and conversely, the flaky mica having a diameter of 7 mm or more shown in Comparative Example 4 is used. When used, a large change was observed in the thermal conductivity after aging after being left for 10 days in an atmosphere of 50 ° C., suggesting the possibility of impeding practical use in either case.
[0048]
Example C
Next, the case where aluminum foil is used as a plate-like filler will be described. Using a core material produced by the same molding method as in Example A and an evaluation method so as to be a composite structure of a rigid polyurethane foam having open cells and an aluminum foil having an average diameter of 1.0 mm, 10^-2The thermal insulation performance (initial value and value after aging after standing at 50 ° C. for 10 days) as a sample corresponding to a vacuum thermal insulation panel enclosed in a packaging material in a vacuum atmosphere of Torr was evaluated.
[0049]
Table 4 shows a vacuum heat insulation panel using the core material having the above-described composition as Example 6. For the purpose of confirming the effect, Example 2 using flake-like mica for the plate-like filler, and open cell Comparative Example 1 using a hard polyurethane foam as a core material and Comparative Example 2 using a core material in which an aluminum foil is sandwiched between open-celled hard polyurethane foams also have an initial value of thermal conductivity and an atmosphere of 50 ° C. The values after standing for 10 days are also shown.
[0050]
[Table 4]

[0051]
As a result of the above, it was confirmed that the heat insulation performance was further improved as compared with the case of using flake-like mica, and in addition, like the open-celled rigid polyurethane foam shown in the comparative example, the heat insulation performance was effectively affected. It was confirmed that it was effective without any deterioration over time.
[0052]
Example D
Next, the effect of suppressing deterioration of the heat insulation performance exerted by the release agent of the rigid polyurethane foam and the plate-like filler obtained by combining the rigid polyurethane foam will be described.
A core material produced by the same molding method as in Example A and an evaluation method so as to form a composite structure with flake-like mica having an average diameter of 1.0 mm, which is obtained by applying a release agent on the surface of a rigid polyurethane foam having open cells. 10^-2The thermal insulation performance (initial value and value after aging after standing at 50 ° C. for 10 days) as a sample corresponding to a vacuum thermal insulation panel enclosed in a packaging material in a vacuum atmosphere of Torr was evaluated.
[0053]
Table 5 shows a vacuum heat insulation panel using the core material having the composition described above as Example 6, and an example using another release agent was shown in Example 2 for the purpose of confirming the effect.
Furthermore, in order to confirm the effectiveness of these examples, an example using flaky mica without applying a release agent is used in Comparative Example 5, and only open-celled rigid polyurethane foam without using a filler is used as a core material. Also for Comparative Example 1, the initial value of thermal conductivity and the value after standing for 10 days in an atmosphere of 50 ° C. are shown together.
[0054]
[Table 5]

[0055]
As a result, even if the release agent is not applied to the surface of the plate-like filler, the initial value of the heat insulation performance can be determined from the difference between Comparative Example 5 and Comparative Example 1, and the open-celled rigid polyurethane foam is used as the core material It was confirmed that an effect far superior to that used in the above was obtained.
However, the numerical value after the change with time showed deterioration as expected to impede practical use. This is because, when using open-celled rigid polyurethane foam, complete communication was insufficient in Comparative Example 5, so that foaming gas such as carbon dioxide was released out of the cell into the remaining closed cells, This is considered to be a phenomenon of deterioration in heat insulation performance caused by a decrease in the degree of vacuum accompanying this.
[0056]
On the other hand, with respect to the effect that the release agent according to the present invention is applied to the surface of flake-like mica, and the separation from the hard polyurethane foam generated thereby eliminates the residual of closed cells, Example 6 and Example 2 From the difference from Comparative Example 5, it was confirmed that the deterioration with time was suppressed.
[0057]
Example E
Next, the effect of improving the heat insulation performance by orienting the plate-like filler charged into the rigid polyurethane foam will be described. The orientation of the plate-like filler is strong because the foaming speed of the rigid polyurethane foam is increased and the ratio of the flow distance to the mold thickness (molded product thickness) (hereinafter referred to as L / T) is large. Become.
[0058]
Using a core material produced by changing the reaction rate and L / T of the open cell rigid polyurethane foam to be used,^-2The heat insulation performance was evaluated using a vacuum heat insulation panel sealed in a packaging material under a Torr vacuum atmosphere as a sample.
The plate-like filler used here uses flaky mica having an average diameter of 1.0 mm, and in order to obtain a composite structure of this and open-celled rigid polyurethane foam, the same molding method as in Example A 10 using the core material and the evaluation method prepared in^-2Thermal insulation performance (initial value and value after aging after standing at 50 ° C. for 10 days) corresponding to a vacuum thermal insulation panel enclosed in a packaging material in a vacuum atmosphere of Torr was evaluated.
[0059]
Table 6 shows the results of examining the influence of the flow rate when molding the core material of the vacuum heat insulation panel used for the evaluation of the heat insulation performance.
Since the foaming flow proceeds at a substantially constant speed from the foaming start time (hereinafter referred to as CT) until the rigid polyurethane foam starts to foam to the resinization time (hereinafter referred to as GT), GT- The core material produced by changing the amount of catalyst used was shown as Example 2, Example 7, and Example 8 together with the composition, with the reaction rate shown as CT (seconds).
[0060]
[Table 6]

[0061]
Similarly, Table 6 shows the vacuum produced by using the core material with different L / T formed by changing the length (flow distance) L of the mold (300W × 500L × 30T) used for molding. The evaluation result of the heat insulation panel was shown as Example 2, Example 7, Example 9, and Example 10.
In addition, for the purpose of confirming these effects, an example using a core material obtained from a rigid polyurethane foam with a slow reaction rate is Comparative Example 6, an example using a core material obtained from a mold having a small L / T Is shown as Comparative Example 7, and the initial value of thermal conductivity and the value after standing for 10 days in an atmosphere of 50 ° C. are shown together.
[0062]
As described above, when the reaction rate was changed from Example 2 to Example 7 and further to Example 8, it was confirmed that the heat insulation performance clearly had a tendency to improve. On the contrary, as shown in Comparative Example 6, it was also confirmed that when the reaction rate was slow, the heat insulation performance was drastically lowered. The cause of these declines is due to the orientation of the flake-like mica, which is a plate-like filler produced by trying to minimize the shear force generated from the speed ratio with the wall surface due to flow, in the plane direction. Conceivable.
[0063]
In addition, as for L / T, when Example 10 is increased to Example 2 and further to Example 9, it is confirmed that the heat insulation performance is similarly improved, and conversely, L / T is very small. Example 7 shows a tendency to deteriorate the heat insulation performance, and it is considered that the orientation of the filler due to the shearing force of the flow described above contributes greatly as a factor.
[0064]
As for the change over time in the heat insulation performance, in each example obtained under appropriate conditions, the result of stopping at a change of 1 to 3 points was obtained. Brought about 7 to 9 points worse.
This is also inherently a crack that tends to cause continuity when peeled off from the plate-like filler that is oriented in the thickness direction, whereas in an insufficiently oriented state, the foam gas becomes discontinuous. It is thought that the situation that it is likely to remain is produced, and the decrease in the degree of vacuum due to the leakage of these gases has resulted in the deterioration of the heat insulation performance.
[0065]
Example F
Next, the effect of improving the stability of the heat insulation performance by removing the surface layer of the foam molded product will be described. A thin layer of resin is present on the outermost surface of the rigid polyurethane foam, and further, there is a core layer having a homogeneous and stable quality called a core layer after having a high-density skin layer below. Among these, the skin layer has a high flow resistance with the mold, and it is a high-density layer that is generated as a result of cracking at the interface with the core layer without flowing in the mold and almost staying on the mold surface. is there. Therefore, it is considered that the surface layer up to the skin layer does not have a shearing force between the bubbles accompanying the flow or between the plate-like fillers, and many closed cells remain.
[0066]
Using a core material prepared by the same molding method as in Example A and an evaluation method, a molded article of open-celled rigid polyurethane foam containing a plate-like filler is 10^-2Thermal insulation performance (initial value and value after aging after standing at 50 ° C. for 10 days) corresponding to a vacuum thermal insulation panel enclosed in a packaging material in a vacuum atmosphere of Torr was evaluated.
Here, a core material in which an arbitrary thickness is uniformly removed from the surface layer is prepared and used, and a flake-like mica having an average diameter of 1.0 mm is used as the plate-like filler, and this is connected to a hard solid bubble. A composite structure with polyurethane foam was obtained.
[0067]
Table 7 shows the composition of the core material used in the vacuum heat insulation panel for evaluating the heat insulation performance, and the amount of the surface layer of the plate-shaped molded product to be removed in order to obtain the core material. Shown as Example 12.
After changing the length L and thickness T of the mold (300W × 500L × 30T) used for molding to make L / T constant (16.6), the plates with thickness T of 25mm, 30mm, 40mm A shaped molded product was prepared, and from this, 2.5 mm, 5.0 mm, and 10.0 mm on the front and back sides were deleted, and a 20 mm thick core material was molded. The vacuum heat insulation panel was produced using these core materials having different surface removal amounts, and the evaluation results of the thermal conductivity thereof are shown in Example 2, Example 11, and Example 12.
[0068]
[Table 7]

[0069]
Further, for the purpose of confirming the stable securing of the thermal conductivity by the removal of the surface layer, an example in which the surface layer is not removed is shown in Comparative Example 8, and an example in which the amount to be removed is reduced in Comparative Example 9, respectively. For the vacuum heat insulating panel using the core material obtained by the same method as described above with the L / T of the material constant, the initial value of the thermal conductivity and the value after standing for 10 days in an atmosphere of 50 ° C. are shown together.
[0070]
As a result, stable results were obtained with little difference in the heat insulation performance of Examples 2, 11 and 12 and with very little change over time.
On the other hand, when the removal amount of the surface layer shown in the comparative example is small, the initial value of the heat insulation performance is not different from the example, but the change with time depends on the amount of removal of the surface layer. It was confirmed that deterioration occurred. A change with time can be suppressed in accordance with the amount of the surface layer to be deleted, and the amount of deterioration when the surface layer is not deleted tends to be the largest. It can be said that the deletion amount in the comparative example cannot be practically used.
[0071]
Example G
Next, the operation performance of the refrigerator using the vacuum heat insulation panel according to the present invention was measured, and the effect was confirmed.
First, using a vacuum insulation panel produced by the same method as Example 1 shown in Example A using a packaging material having an aluminum foil as an intermediate layer, an ABS resin is placed in an outer box 8 obtained by bending a thin steel plate. In the space formed by fitting the inner box 9 obtained by vacuum forming, a vacuum heat insulating panel 7 was attached to the outer box 8 side as shown in FIG. In this state, as shown in FIG. 6, the rigid polyurethane foam 10 was injected into the remaining space, foamed and filled to be completely fixed.
[0072]
A 400 L-class refrigerator assembled using the heat insulating box produced by the above method was named Example 13.
On the other hand, the refrigerator using the heat insulation box which produced similarly the core material produced by the same method as the comparative example 1 shown in Example A using the hard polyurethane foam of the open cell as a core material is a comparative example. 10. The heat insulation box which filled all the gap | intervals of an inner box and an outer box with the hard polyurethane foam was made into the comparative example 11, and calculated | required power consumption according to the power consumption B method measurement method in all these refrigerators in JIS9607, Table 8 is also shown.
[0073]
[Table 8]

[0074]
From the above results, the power consumption of the refrigerator using the vacuum heat insulation panel of the present invention is less than that of the conventional refrigerator of Comparative Example 11 using only rigid polyurethane foam as the heat insulating material, and the heat insulation performance of the box is low. It turns out that it is significant. Moreover, even when compared with a refrigerator using the same vacuum heat insulating panel as a part of the heat insulating material, than the refrigerator of Comparative Example 10 using the vacuum insulating panel of the conventional specification in which the open polyurethane hard polyurethane foam is the core material, It was also confirmed that a refrigerator with low power consumption can be obtained.
[0075]
As mentioned above, although the refrigerator which is embodiment of this invention was demonstrated, this invention is not limited to this, For example, the small vehicle-mounted refrigerator, the prefabricated simple refrigerator, the cooler vehicle, a pipe, and the heat insulating material of a building The heat insulation and cold insulation products can be applied as heat insulation parts, and various modifications can be made without departing from the scope of the invention.
[0076]
【The invention's effect】
As is clear from the above description, according to the present invention, the following effects can be obtained. In the description, the same number as the number of the claim is attached and the effect of each claim is described.
[0077]
(1) The vacuum heat insulation panel according to the present invention maintains the shape by the core material.do itVacuum insulation panel, Crushed pieces or cut pieces that have been given release propertiesConsists of a porous body made of open-cell rigid polyurethane foam containing a plate-like fillerThen, the surface of the plate-like filler was oriented parallel to the surface direction of the core materialTherefore, the panel shape in a vacuum state can be maintained, the amount of heat transfer and radiation transfer can be suppressed, and the heat insulation is also large.In addition, since the release agent is applied to the surface of the plate-like filler, when the urethane resin and the plate-like filler are peeled, the cells can be connected more reliably and more reliably penetrated. In addition, the peeling also creates an effect of preventing the propagation of heat in a vacuum by forming new voids, and the heat insulation is dramatically improved. Further, the surface of the plate-like filler is oriented in a direction perpendicular to the heat penetration direction, and excellent heat insulation performance and stability over time can be ensured by improving the radiant heat shielding effect.
[0078]
(2) the above(1)Since at least one of an inorganic substance and a metal is used for the plate-like filler, the radiant heat is easily reflected, and the heat insulating property is improved by the shielding effect.
(3) the above(2)Since flaky mica is used as the plate-like filler, the radiant heat is easily reflected, and the heat insulating property is improved by the shielding effect.
[0079]
  (4) the above(2)Since the plastic film is used for the plate-like filler, the radiant heat is easily reflected, and the heat insulating property is improved by the shielding effect.
  (5) the above(2)Since the plastic film which coat | covered the metal thin film was used for this plate-shaped filler, it is easy to reflect radiant heat, and the heat insulation improves by the shielding effect.
[0080]
  (6) the above(2)Since the metal foil is used for the plate-like filler, the radiant heat is easily reflected, and the heat insulating property is improved by the shielding effect.
  (7) the above(5), (6)Since aluminum is used for the metal thin film or metal foil, the radiant heat is easily reflected, and the heat insulating property is improved by the shielding effect.
[0081]
  (8) Above (1), (2), (3), (4), (5), (6)Or (7)Since the size of the plate-like filler is made larger than the cell size of the rigid polyurethane foam, the connection of the cells can be promoted efficiently.
  (9) the above(1)Since the surface layer of the core material is removed, the shielding effect of radiant heat is improved, and excellent heat insulating performance and stability over time can be ensured.
[0082]
  (10The manufacturing method of the vacuum heat insulation panel by this invention is a plate-shaped filler.Apply release agent to the surface of the plate and fill it with plateAnd rigid polyurethane foamWithThe raw material liquid is mixed and injected from the end of the plate mold, foamed from the end, and sheared in the flow direction, and the surface of the plate filler is oriented parallel to the surface direction of the plate molded product.Removed the surface layer of the resulting molded productTherefore, the plate-like filler can be oriented perpendicular to the heat transfer direction, and the heat insulation can be further improved by blocking the radiant heat transfer.Since the release agent is applied to the surface of the plate-like filler, cell communication is more reliably achieved when the urethane resin and the plate-like filler are peeled off, and the cells are penetrated more reliably. Since the surface layer of the core material is eliminated, the shielding effect of radiant heat is improved, and excellent heat insulation performance and stability over time can be ensured.
[0083]
  (11)(10) aboveThe plate-shaped filler is added immediately before mixing the premix liquid and the isocyanate liquid, which are raw liquid materials for rigid polyurethane foam, and these mixed raw materials are injected from the end of the plate mold in time for foaming. Since the foaming is applied to the flow direction by subsequent foaming and the surface of the plate-like filler is oriented parallel to the surface direction of the plate-like molded product, the plate-like filler is perpendicular to the heat transfer direction. The heat insulation can be further improved by blocking radiation heat transfer. In addition, handling at the time of manufacture is easy, and mass productivity is excellent.
[0084]
  (12) Since the size of the plate-like fillers of (10) and (11) is made larger than the cell size of the rigid polyurethane foam, it is possible to efficiently promote cell communication.
  (13) (10), (11)Or (12)Since the ratio L / T of the molded product thickness T to the flow distance L of the foaming liquid is 10 or more, the heat insulation performance can be greatly improved.
[0085]
  (14The refrigerator according to the present invention is a vacuum according to any one of (1), (2), (3), (4), (5), (6), (7), (8), (9). Since the heat insulating panel is disposed between the inner box and the outer box, the heat insulating property is increased and the power consumption can be reduced.
[0086]
  (15) the above(14)Since the vacuum insulation panel was affixed to the inner box or outer box and the remaining space was filled with rigid polyurethane foam, the above(14)With this effect, the outer box and inner box can be completely fixed, and there is no need to change the conventional structural specifications.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a manufacturing process of a vacuum heat insulating panel.
FIG. 2 is a side view showing a vacuum heat insulating panel manufacturing apparatus.
FIG. 3 is an explanatory view showing a product assembly process using a vacuum heat insulation panel.
FIG. 4 is a perspective view of a product incorporating a vacuum insulation panel.
5 is a longitudinal sectional view of a main part of FIG.
FIG. 6 is a diagram showing the vacuum degree dependency of the heat insulation performance.
FIG. 7 is an explanatory diagram comparing the heat insulating performance of each heat insulating material.
[Explanation of symbols]
2 core material, 7 vacuum insulation panel, 8 outer box, 9 inner box, 10 rigid polyurethane foam.

Claims (15)

In the vacuum insulation panel that holds the shape by the core material,
The core material is composed of a porous body made of open-celled rigid polyurethane foam containing a plate-like filler of pulverized pieces or cut pieces provided with releasability, and the surface of the plate-like filler is the surface of the core material A vacuum insulation panel characterized by being oriented parallel to the direction.   The vacuum heat insulating panel according to claim 1, wherein at least one of an inorganic material and a metal is used for the plate-like filler.   The vacuum heat insulation panel according to claim 2, wherein flake-like mica is used for the plate-like filler.   The vacuum insulation panel according to claim 2, wherein a plastic film is used for the plate-like filler.   The vacuum insulation panel according to claim 2, wherein a plastic film in which a metal thin film is coated on the plate-like filler is used.   The vacuum heat insulating panel according to claim 2, wherein a metal foil is used for the plate-like filler.   7. The vacuum heat insulating panel according to claim 5, wherein aluminum is used for the metal thin film or the metal foil.   The vacuum heat insulating panel according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the size of the plate-like filler is larger than the cell size of the rigid polyurethane foam.   The vacuum heat insulation panel according to claim 1, wherein a surface layer of the core material is deleted.   A release agent is applied to the surface of the plate-like filler, the raw material liquid of the plate-like filler and rigid polyurethane foam is mixed, injected from the end of the plate-shaped mold, and foamed from the end to flow. A method for producing a vacuum heat insulating panel, wherein the direction of the plate-like filler is applied in parallel, the surface of the plate-like filler is oriented parallel to the surface direction of the plate-like molded product, and the surface layer of the obtained molded product is deleted.   The plate-like filler is added immediately before mixing the premix liquid and the isocyanate liquid, which are raw liquids of rigid polyurethane foam, and these mixed raw materials are injected from the end of the plate-shaped mold in time for foaming, 11. The vacuum heat insulating panel according to claim 10, wherein foaming is performed from an end portion, shear is applied in the flow direction by subsequent foaming, and the surface of the plate-shaped filler is oriented parallel to the surface direction of the plate-shaped molded product. Manufacturing method.   The method for manufacturing a vacuum heat insulating panel according to claim 10 or 11, wherein the size of the plate-like filler is larger than the cell size of the rigid polyurethane foam. The method for manufacturing a vacuum heat insulating panel according to any one of claims 10 to 12 , wherein a ratio L / T of a molded product thickness T to a flow distance L of the foaming liquid is 10 or more.   A refrigerator comprising the vacuum heat insulation panel according to any one of claims 1 to 9 disposed between an inner box and an outer box. The refrigerator according to claim 14, wherein the vacuum insulation panel is attached to the inner box or the outer box, and the remaining space is filled with hard polyurethane foam.

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