JP3710320B2

JP3710320B2 - Heat insulation core material, method for producing the same, and vacuum heat insulation material

Info

Publication number: JP3710320B2
Application number: JP08689799A
Authority: JP
Inventors: 敬治佐々木; 宏吉村
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 1999-03-29
Filing date: 1999-03-29
Publication date: 2005-10-26
Anticipated expiration: 2019-03-29
Also published as: JP2000280266A

Description

【０００１】
【発明の属する技術分野】
本発明は、冷蔵庫や冷凍庫等に使用する真空断熱材およびその製造方法に関するものである。
【０００２】
【従来の技術】
近年、真空断熱材の断熱性能を向上させる目的で、例えば特開平５−６５９９０号公報に開示されているように、発泡ウレタン原料を発泡させたウレタンフォームを芯材とし、これを通気性をもたない樹脂フィルム等で被覆し、その内部を減圧して密閉する真空断熱材の製造方法が注目されている。以下、特開平５−６５９９０号公報の真空断熱材の製造方法を図７〜図９を参照して説明する。
【０００３】
図７に示すように、通気性を有する治具２５に、通気性を有する紙や不織布等からなる面材２６を載せ、この中に気泡連通化材を含む発泡ウレタン原料を注入発泡して硬質ウレタンフォームブロック２４を得る。さらに、この硬質ウレタンフォームブロック２４を任意の大きさに切断して、図８に示すような硬質ウレタンフォームパネル２７とする。そして、この硬質ウレタンフォームパネル２７を高温で長時間加熱し、吸着水分等を蒸発させ金属−プラスチックスラミネートフィルムからなる容器２３で被覆し、内部を減圧にして密閉することにより、図９に示すような真空断熱材２８が得られる。このようにして製造された真空断熱材２８は、内部の前記硬質ウレタンフォームパネル２７（芯材）の連通気泡率が高いため、長期間の使用に対しても経時的な断熱性能の劣化がほとんどない。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記従来の真空断熱材の製造方法では、連通気泡率を高めるため、発泡ウレタン原料に気泡連通化剤を混入させているが、ウレタンフォームブロックを大量生産すべく工業的に実施した場合、気泡連通化剤の種類や使用量によっては独立気泡が硬質ウレタンフォームの表面のスキン部やその近くに多く残留しているため、該ウレタンフォームを真空断熱材に加工したときの断熱性能が低下し、特に長期間（３０日以上）の使用により残留独立気泡内から経時的にガスが拡散して、内部圧力を高めて断熱効率を劣化させるという問題があった。
【０００５】
さらに、ウレタンフォームブロックを切断してウレタンフォームパネルに加工する必要があるため、真空断熱材を製造する際の作業工程数が増加し、手間がかかり生産コストが高くなるだけでなく、フォーム廃材や加工粉塵が大量に発生するため、廃棄物処理コストの面のみならず資源的に無駄が多い等環境の上でも課題があった。
【０００６】
本発明は、上記従来の問題点に鑑みてなされたものであり、廃棄物処理等の環境上の問題がなく、長期間の使用に対しても性能が劣化しない真空断熱材を提供することを目的とする。
【００１３】
【課題を解決するための手段】
本発明の断熱材用芯材の製造方法は、通気性を有する材料で発泡ウレタン原料を覆って発泡治具に収容し、その周辺又は前記発泡治具を所定の温度に保って発泡させ、前記所定の温度は７５℃以上１３０℃以下であり、前記通気性を有する材料は前記発泡ウレタン原料を前記発泡治具から隔離させるとともに、前記通気性を有する材料を隔てて、前記発泡ウレタン原料周辺を減圧させて発泡させることを特徴とするものである。
【００１４】
この構成によると、発泡ウレタン原料の発泡中に、特に独立気泡の残留しやすい表面のスキン部やその近くも加熱作用により軟化状態を維持しながら発泡するので、独立気泡が破泡しやすくなり、連通気泡化が促進される。
【００１６】
この構成によると、独立気泡の残留が少ない連通気泡構造の発達した断熱材用芯材が得られる。
【００２０】
この構成によると、発泡ウレタン原料の発泡中に、特に独立気泡の残留しやすい表面のスキン部やその近くも減圧による吸引作用を受けながら発泡するので、独立気泡が破泡しやすくなり、連通気泡化が促進される。
【００２５】
また、前記通気性を有する材料がクラフト紙であり、その目付け量は５０〜１４０ｇ／ｍ²であることを特徴とするものである。
【００２６】
この構成によると、通気性を有する材料が適度な強度と成型加工性をもつとともに、発泡ウレタン原料を発泡させる前に該発泡ウレタン原料が、通気性を有する材料であるクラフト紙の外部へ染み出す恐れがない。
【００２９】
また、前記通気性を有する材料を少なくとも一方に開口部を有する袋状にし、前記開口部近くや前記通気性を有する材料の他方の接着部に穴や切り欠きを設けたことを特徴とするものである。
【００３０】
この構成によると、例えば発泡治具に凸部を設けておき、該凸部に通気性を有する材料に設けた穴や切り欠きを嵌合させたり、添わせたりすることにより、前記穴や切り欠きが位置決めの役割を果たすので、通気性を有する材料の前記発泡治具内への収容が容易になるとともに、前記発泡治具内における前記通気性を有する材料の移動が阻止される。
【００３３】
また、前記発泡治具を気密空間内に設けるか、前記発泡治具内を気密室とし、前記気密空間あるいは前記気密室から減圧を行うための真空ポンプまでの経路の途中に分岐経路を設け、該分岐経路には予め減圧された減圧ストックタンクが連結されており、前記真空ポンプを駆動してから、前記発泡ウレタン原料が発泡を開始し、生成した気泡の破泡が進行するタイミングで、前記分岐経路の途中に設けられたバルブを開き、前記発泡ウレタン原料の発泡が完了し硬化してウレタンフォームとなるまで前記真空ポンプで減圧を続けることを特徴とする。また、本発明の断熱材用芯材は上記のいずれかの断熱材用芯材の製造方法により製造されたことを特徴とするものである。また、本発明の真空断熱材は、上記の断熱材用芯材を外包材で被覆し、内部を減圧して密閉したことを特徴とするものである。
【００３４】
この構成によると、得られた芯材をそのままあるいは適当な大きさに切り出して真空断熱材に利用することができるため、加工の手間が省けるとともに、ウレタンフォームの廃材の出る量が減少し、廃棄物処理等の環境上の問題のない真空断熱材を低コストで提供できる。
【００３５】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照して説明する。図１は、いずれも通気性を有するクラフト紙等からなる外皮材の斜視図である。まず、この図を用いて外皮材２に発泡ウレタン原料３を注入する手順を説明する。図１（ａ）に示すように、外皮材２を筒状に丸めて重なった部分の互いに向かい合う面を接着する。これにより、外皮材２の底部略中央部には、この外皮材２の長さ方向に伸びる接着部２ｃが形成される。また、外皮材２の両端には開口部２ａ、２ａが形成される。
【００３６】
そして、一方の開口部２ａを図１（ａ）の矢印で示すように閉じて接着する。これにより、図１（ｂ）に示すように外皮材２には略長方形の扁平部２ｂが形成され、外皮材２は他方の開口部２ａが開放された袋状となる。次に、この袋状の外皮材２の開口部２ａから発泡ウレタン原料３を適量注入する。尚、発泡ウレタン原料３は有機ポリイソシアネート、ポリオール、触媒、整泡材、発泡剤からなる混合原料であり、発砲後硬化してウレタンフォームとなる。
【００３７】
次に、本発明に係る断熱材用芯材を製造する装置の構成を説明する。図２は、本発明の一実施例の断熱材用芯材の製造時の断面図である。図２において、４は上治具、５は下治具であり、それぞれ上チャンバ６、下チャンバ７に取り付けられている。この上チャンバ６と下チャンバ７とに挟まれた部分には気密空間９が形成され、該気密空間９における上治具４および下治具５の周辺には、耐熱性の絶縁体で被覆され可撓性を有する電気発熱体からなるヒータ８が配設されている。尚、このヒータ８は前記上治具４や下治具５に埋設させてもよい。
【００３８】
また、１０は真空ポンプであり、該真空ポンプ１０と前記気密空間９とはパイプ１２で連通されている。そして、パイプ１２の途中から分岐したパイプ１２ａには減圧ストックタンク１１が連結されており、前記パイプ１２、１２ａにより該減圧ストックタンク１１と前記気密空間９とは連通されている。さらに、パイプ１２の分岐点より前記気密空間９側ならびに前記分岐点から分岐したパイプ１２ａには、それぞれバルブ１３、１４が設けられており、気密空間９と真空ポンプ１０および減圧ストックタンク１１との連通を開放あるいは閉鎖すべく、必要に応じてこれらのバルブ１３、１４を開閉するようになっている。前記減圧ストックタンク１１は予め前記真空ポンプ１０にて減圧されており、その状態で前記バルブ１３、１４が閉じられている。
【００３９】
そして、前記上治具４および下治具５には、それぞれ貫通する穴からなり前記パイプ１２に通ずる複数の治具開口部４ａおよび５ａと、前記外皮材２の開口部２ａや扁平部２ｂを挟んで固定するための治具封止部４ｂおよび５ｂとが設けられている。尚、発泡治具４、５にそれぞれ前記治具開口部４ａ、５ａを設ける代わりに、これらの発泡治具４、５自体をセラミック発泡体等の通気性を有する材質で構成してもよい。
【００４０】
また、外皮材２内に注入された発泡ウレタン原料３の肉厚の薄い部分には、前記ヒータ８の発熱量を小さくしたり、ヒータ分布を粗くしたりすることにより、発砲治具４、５内の各部に伝わる熱量を該部に必要な温度条件に応じて調節するようにしてもよい。さらに、発砲治具４、５の外皮材２に近接する部分の数カ所に温度感知手段を設けて、該温度感知手段が感知した温度情報に基づき局所的にヒータ８の発熱量を調節するようにしてもよい。これにより、外皮材２内の発泡ウレタン原料３の全体にわたって適度にヒータ８の熱が伝達され、発泡ウレタン原料３の発泡を安定して行わせることができる。さらに、前記ヒータ８の代わりに、暖められた水やオイル等の液体あるいはスチームや空気等の気体をパイプ内に通したものを用いてもよい。
【００４１】
以上のような構成の装置を用いて断熱材用芯材を製造する手順について説明する。まず、前記下治具５の治具封止部５ｂに前記発泡ウレタン原料３を注入した外皮材２（図１（ｂ）参照）の開口部２ａおよび扁平部２ｂが乗り上げるように、外皮材２を下治具５に載置する。そして、上治具４が取り付けられた上チャンバ６を下チャンバ７にセットすることにより、発砲治具４、５内に外皮材２を収容する。これにより、前記開口部２ａおよび扁平部２ｂは発泡反応が完了して前記発泡ウレタン原料３が硬化するまで、治具封止部４ｂ、５ｂでそれぞれ挟み込まれるので、発泡ウレタン原料３の侵入がない扁平な状態となる。そのため、この扁平部２ｂは芯材１の作成が完了後、容易に折り曲げることができる。
【００４２】
そして、前記上チャンバ６と下チャンバ７の接続箇所には、オーリング等で着脱可能な状態にシールされ、その内部が気密状態になるようにしてある。また、前記気密空間９の代わりに、前記上治具４と下治具５の治具開口部４ａ、５ａをパイプ１２に直接つなぎ、治具封止部４ｂ、５ｂ近くを含む前記治具周辺にオーリング等でシールし、芯材１の収まる部分を気密室とすると、上チャンバ６と下チャンバ７がなくても上記と同様の減圧作用が期待でき、設備をさらに小型化できる。さらに、図２では上下方向でチャンバを開く構造にしているが、この部分を９０°回転させた状態にして横方向でチャンバを開く構造にすると、さらに設置スペースをとらない装置となる。
【００４３】
さらに、図３に示すように下治具５の治具封止部５ｂに凸部５ｃを設け、該凸部５ｃを前記外皮材２の扁平部２ｂに開けた穴部２ｄに通すとともに、上治具４の前記凸部５ｃに対向する位置に設けた凹部４ｃに前記凸部５ｃを嵌合することにより、外皮材２を発砲治具４、５内部の最適な位置に容易に収容することができるだけでなく、一旦外皮材２が前記発泡治具４、５に収容されると、該外皮材２の前記発泡治具４、５内部での大幅な移動が阻止されるので、発泡ウレタン原料３の発泡反応を常に安定して同じ条件の下で行うことができる。尚、図３は外皮材２の扁平部２ｂに穴部２ｄを設ける場合を示しているが、この穴部２ｄの代わりに位置決め用の切り欠きを入れて、この切り欠きを前記凸部５ｃに添わせるようにしてもよい。さらには、外皮材２の開口部２ａの近くにも位置決め用の穴や切り欠きを設けてもよい。
【００４４】
そして、開口部２ａの近く又は扁平部２ｂのどちらか一方の切り欠き又は穴に開口部２ａに対して直角方向に前記凸部５ｃに対するアソビを設けておくと、一層前記外皮材２を下治具５へセットするのが容易になる。また、前記アソビは発砲ウレタン原料が発砲することにより、開口部２ａに対し直角方向で外皮材２の長さが不足したときの外皮材２のズレのために必要となり、このズレ以上のアソビとなっている。さらに、外皮材２のズレが必要な側の治具封止部４ｂ、５ｂの外皮材２の挟み込む力は、外皮材２がずれる程度のものである。治具封止部４ｂ、５ｂ以外で芯材１付近の上治具４や下治具５は、上チャンバ６を下チャンバ７にセットしたとき、外皮材２を挟まないように少し隙間をあけておくとよい。
【００４５】
上治具４および下治具５は前記ヒータ８により予め所定の温度に熱せられており、少なくとも前記発泡ウレタン原料３の発泡反応が完了するまでは前記所定の温度を保つように設定されている。この状態で、上チャンバ６を下チャンバ７にセットした後、真空ポンプ１０を駆動してバルブ１３を開く。そして、発泡ウレタン原料３が発泡を開始し、生成した気泡の破泡が進行するタイミングでバルブ１４を開く。このまま、発泡ウレタン原料３の発泡が完了するまでバルブ１３を開いて、前記気密空間９内を真空ポンプ１０で減圧し続ける。発泡ウレタン原料３の発泡が完了し硬化してウレタンフォーム３ａとなった時点で、前記気密空間９内を大気圧に戻す。そして、上チャンバ６を下チャンバ７から取り外して、外皮材２とその内部のウレタンフォーム３ａとで構成される芯材１を取り出す。
【００４６】
図４は芯材の側面断面図であり、図５は図４におけるＡ−Ａ断面図である。これらの図において、１ａは陥没部であり、該陥没部１ａは発泡ウレタン原料３が発泡しながら膨張する際、上治具４に設けられた略長方形の突出部４ｃに芯材１が押圧されることにより、突出部４ｃの形状を反映して長方形状に形成される。また、１ｂ、１ｃは芯材１周縁のコーナー部であり、該コーナー部１ｂ、１ｃは発泡ウレタン原料３の発泡時に、外皮材２が発砲治具４、５内部の前記コーナー部１ｂ、１ｃに対応する部分の丸みを帯びた形状に添うことにより曲面に仕上がる。即ち、芯材１の凹部を含む全コーナー部は適度な曲面となるように上治具４や下治具５は作られている。
【００４７】
また、上治具４と下治具５とで形成される芯材１を収容するための空間において、厚さ方向の寸法は芯材１が所定の厚さとなるようにする必要があるが、外皮材２の強度が前記発泡ウレタン原料３の発泡力に打ち勝つ場合、前記コーナー部１ｂや１ｃ等の芯材１のコーナー部付近に対応する上治具４や下治具５のコーナー部を芯材１の曲面と異なる小さな曲率半径による形状にして隙間が生じるようにしてもよく、場合によっては上治具４や下治具５の前記コーナー部を角張った形状にしておいても、前記発泡ウレタン原料３の発泡硬化後の状態で、前記発泡治具４、５のコーナー部と外皮材２との間に、隙間が生じる寸法関係にあれば、芯材１の前記コーナー部は曲面に仕上がる。
【００４８】
また、このように外皮材２と発砲治具４、５内部との間に常時隙間をもたせることによって、発泡ウレタン原料３の発泡時、真空ポンプ１０による吸引を促進させることができる。即ち、短時間で広範囲にわたる減圧効果を得ることができるため、ウレタンフォーム３ａ内部の連通気泡構造のさらなる均一化、低密度化を図ることができる。
【００４９】
尚、図１に示すように外皮材２は底部の略中央部に長さ方向に伸びる接着部２ｃを有しているが、この接着部２ｃは、クラフト紙等からなる外皮材２を円筒状に丸めて内面となる側を重ね合わせて接着し、その接着根本付近で折り曲げて片側に倒した状態にしてもよく、さらに、この接着面を芯材の長さ方向や幅方向の少なくとも一端に設けてもよい。この場合は、外皮材２の内面側に発砲ウレタン原料３を注入したとき、少なくとも発砲完了間際まで、前記発砲ウレタン原料３に接する外皮材２の全周囲が通気性のよい一重の面となり、発砲後のウレタンフォーム３ａには連通気泡がさらに均一に形成される。さらに、上記のような接着部となる付近の外皮材２に、予め熱溶着性プラスチックスを付けておき、ローラー等により熱プレスして接着するようにすると量産性が向上する。
【００５０】
また、発泡後硬化した芯材１に不必要な突起部やエッジ部があるとき、その部をハンマー等でたたいたり押し型や治具で押して曲面や平面や凹面にしておくと、前記突起部やエッジ部で、後述する真空断熱材の外包材が破れる恐れがなくなる。また、上記のような芯材１のコーナー部は、Ｃ面状に形成させてもよい。尚、芯材１のコーナー部の曲面とそれに対応する上治具４や下治具５のコーナー部の間に隙間や溝をもたすことにより、この付近が減圧通路となり、より一層早い時間で広範囲かつ均一に減圧できるようにもなり、芯材１内の連通気泡のさらなる均一化や低密度化を効率よく達成できる。
【００５１】
図６は、本発明の一実施例の真空断熱材の側面断面図である。図６において、１５は芯材１の内部から発生したり、真空断熱材１８の外部から侵入する微量のガスや水分等を吸着除去するための吸着剤であり、該吸着剤１５は通気性を有する粘着テープ１６で前記陥没部１ａに封入されている。また、１７はガスバリヤー性のある物質（例えば、アルミ蒸着ポリエステルフィルムと金属箔熱溶着性のプラスチックのラミネートからなる通気性のない薄膜材）からなる外包材である。
【００５２】
このような構成をもつ真空断熱材１８の作成手順について説明すると、上記方法で製造された芯材１の外皮材２の両端の扁平部２ｂ、２ｂを根本から上方へ折り曲げて、図示の如く外皮材２の外周面に密着するように添わせテープ等で固定した後、この芯材１を１２０〜１３０℃の乾燥炉に２時間程度収容し、芯材１内部のウレタンフォーム３ａの水分やガスを蒸発させて充分に乾燥させる。そして、乾燥炉から取り出した芯材１の陥没部１ａに前記吸着剤１５を適量注入した後、前記テープ１６で前記陥没部１ａ全体を覆うように封止して芯材組品を得る。さらに、この芯材組品を一端に開口部１７ａをもつ袋状に形成された外包材１７に詰め、該外包材１７内部を真空槽で減圧して前記開口部１７ａを熱シールすることにより、前記芯材組品が外包材１７に密閉された真空断熱材１８が得られる。
【００５３】
尚、図６に示すように、前記扁平部２ｂを外皮材２の前記陥没部１ａが形成されている側に折り曲げることにより、反対側を平坦な面とすることができるので、得られた真空断熱材１８を冷蔵庫の外壁材等の内側平面部に張り付けやすくなる。また、発泡ウレタン原料３を発泡硬化させた後、芯材１の外皮材２に穴や切り込みを設けておくと、該穴や切り込みから直接ウレタンフォーム３ａの水分やガスが外部に放出されやすくなるので、芯材１を乾燥炉に入れて乾燥させたり、前記芯材組品を外包材１７で包み、その内部を真空引きするのに要する時間を短縮することができる。また、前記芯材１の開口部２ａ付近および接着部の扁平になった扁平部２ｂ、２ｂを取り去って芯材１に使用してもよく、さらに、開口部２ａ付近および扁平部２ｂを外皮材２を折り返した後に接着して、治具封止部４ｂ、５ｂで挟み込まないようにし、この部に扁平部が生じないようにしてもよい。
【００５４】
また、冷蔵庫等の真空断熱材を張り付ける外壁材の内側で、その部に凝縮パイプを張り付ける等した凸部がある場合、それに該当する側の真空断熱材の芯材に外包材の厚さ等を考慮して、前記凸部に対応した凹部や前記凸部のある領域をさけた凹部が形成されるように発泡治具に突出部を設けると、切削屑を出すことなく容易に芯材へ前記凹部を形成させることができる。
【００５５】
今、治具内寸法を４４０×７００×１５（ｍｍ）とし、外皮材２として目付け量８０ｇ／ｍ²のクラフト紙を用い、下記の表１に示す様々な条件で発泡ウレタン原料３を発泡硬化させて芯材１を製造した。ところで、発泡ウレタン原料３を発泡させて得られるウレタンフォーム３ａの品質の良し悪しを評価するための指標として、通常次式で定義される連通気泡のオープン化度を用いる。このオープン化度の値も合わせて表１に示す。
オープン化度（％）＝（Ｖ−Ｑ）／Ｖ×１００・・・・・（１）
ここで、Ｖは断熱材内の空間容積（ｃｃ）、Ｑは断熱材内の発生ガス容積（ｃｃ）である。また、
Ｑ＝（Ｐ１−Ｐ０）×Ｖ／７６０
が成り立つ。ここで、Ｐ０は断熱材内の初期圧力（Ｔｏｒｒ）、Ｐ１は断熱材内の２４時間後の圧力（Ｔｏｒｒ）である。
【００５６】
前記（１）式で定義されるオープン化度が低い値のときは、特にウレタンフォーム３ａの表面であるスキン部やその近くには独立気泡が多く残留しており、このようなウレタンフォーム３ａをそのまま真空断熱材１８の芯材１として用いた場合、前記独立気泡内の残留ガスが真空断熱材１８内に充満して真空度が低くなり、真空断熱材の使用の初期から断熱性能の劣化が見られる。
【００５７】
【表１】

【００５８】
発泡ウレタン原料３の注入量が３６３ｇで、上治具４および下治具５の治具温度を３０℃にして、気密空間９内を減圧せずに発泡ウレタン原料３を発泡させた場合、発砲治具４、５内におけるウレタンフォーム３ａの充填が不完全な状態となり、前記オープン化度は８９．５％と低く、ウレタンフォーム３ａのスキン部やその近くには独立気泡が多く残留しており、真空断熱材１８として使用できる部分は芯材１全体の約５０％であった。
【００５９】
また、発泡ウレタン原料３の注入量を２８２ｇとし、気密空間９内を減圧する以外は上記と同様の条件で発泡ウレタン原料３を発泡させた場合、該発泡ウレタン原料３が上治具４および下治具５内全体に発泡し、ウレタンフォーム３ａは完全充填状態となるが、連通気泡のオープン化度は９２．１％と依然として低く、ウレタンフォーム３ａのスキン部やその近くには独立気泡がまだかなり残留しており、真空断熱材として使用できる部分は芯材１全体の約６０％にとどまったものの、気密空間９内を減圧した分、真空断熱材１８として使用できる部分の割合はわずかながら向上した。
【００６０】
即ち、上治具４および下治具５内で発泡ウレタン原料３を発泡させる際に、気密空間９内を減圧することにより、特に独立気泡の残留しやすいスキン部やその近くも発泡中に外部から吸引されて独立気泡が破泡しやすくなり、連通気泡化が促進されるため、独立気泡の残留した部分の少ないウレタンフォーム３ａが得られる。また、発泡ウレタン原料３の注入量を８１ｇも少なくしても、発砲治具４、５内部でウレタンフォーム３ａが完全充填状態となり、減圧によるウレタンフォーム３ａの低密度化と相俟って、少ない原料で芯材１が得られるため、その分フォーム廃材の量が減って廃棄物処理等の環境上も問題もほとんどない真空断熱材を低コストで提供できる。
【００６１】
さらに、上治具４および下治具５の治具温度を７５℃とする以外は上記と同様の条件で発泡ウレタン原料３を発泡させた場合、該発泡ウレタン原料３が上治具４および下治具５内全体に発泡し、ウレタンフォーム３ａは完全充填状態となり、連通気泡のオープン化度は９９．８％に向上した。これにより、独立気泡の残留した部分がほとんどなくなり、吸着剤１５を適量併用すると、１００％真空断熱材１８として使用できる芯材１が得られる。
【００６２】
即ち、気密空間９内を減圧するとともに治具温度を７５℃に保つことにより、特に独立気泡の残留しやすいスキン部やその近くも発泡中に外部からの吸引作用と加熱による軟化作用により独立気泡が破泡しやすくなり、連通気泡化が促進されるため、ほとんど全ての箇所で独立気泡の残留した部分のない連通気泡構造の芯材１が得られる。この芯材１はこのまま真空断熱材１８に加工できるため、従来のようにウレタンフォームブロックから所定の大きさの芯材を切り出す必要がなく、その分加工の手間が省け、しかもフォーム廃材が出ることないので、廃棄物処理等の環境上の問題もなく、コスト削減が可能な真空断熱材を提供できる。
【００６３】
さらに、上治具４および下治具５の治具温度を１１０℃にする以外は上記と同様の条件で発泡ウレタン原料３を発泡させた場合は、連通気泡のオープン化度は９９．９％となり、この場合も吸着剤１５を併用することにより、１００％真空断熱材１８に使用できる芯材１が得られた。
【００６４】
そして、上治具４および下治具５の治具温度を５５℃にした場合は、連通気泡のオープン化度は９９．１％となり、ウレタンフォーム３ａのスキン部やその近くには独立気泡の残留が少しあるが、この部を除去することにより、真空断熱材１８として使用できる部分は芯材１全体の約８５％となり、廃材の量はかなり減少した。
【００６５】
このように発泡ウレタン原料３の発泡が完了するまで発泡治具を暖めることにより、特に独立気泡が残留しやすいスキン部やその近くでも原料は軟化を維持したまま発泡するので、独立気泡が破泡しやすくなり、独立気泡の残留の少ないウレタンフォーム３ａが得られるため、従来方法に比べてフォーム廃材の量がかなり減り、その効果は治具温度が５５℃以上で顕著に現れ、特に７５℃以上の場合は吸着剤を適量併用することによりほぼ１００％真空断熱材１８として使用できる芯材１が得られる。尚、前記治具温度はウレタン材料の耐熱性から上限は１４０℃であり、工業的に実施した場合の品質のバラツキ等を考慮すると前記上限は１３０℃とする必要がある。
【００６６】
また、外皮材２として目付け量が５０ｇ／ｍ²未満のクラフト紙を用いた場合、発泡前の発泡ウレタン原料の一部がクラフト紙に染み込み該クラフト紙の外部へ漏れ出し、これが接着剤のように作用してウレタン原料の発泡硬化後に芯材１が発泡治具４、５に張り付き、該芯材１を発泡治具４、５から取り出しにくくなった。
【００６７】
そして、外皮材２として目付け量が１４０ｇ／ｍ²を超えたクラフト紙を用いた場合、外皮材２が硬くなるため成型加工性に劣り、しかも治具内形状に添いにくくなるため、所望の形状の芯材１が得られなくなる。さらに、外皮材２の通気性も悪くなるため、芯材１の製造時の減圧効果が低下して独立気泡の少ない良質の芯材１が得られなくなるという問題が生じた。
【００６８】
即ち、外皮材２として目付け量が５０〜１４０ｇ／ｍ²のクラフト紙を用いることにより、クラフト紙に適度な通気性をもたすことができるとともに、発泡前のウレタン原料の外皮材２外部への染み出しによる発泡治具４、５への張り付きもなく、しかもこのクラフト紙の硬さや強度が成型加工性に適しているため、所望の形状をした芯材１が容易に得られる。こうして得られた芯材１の周囲はクラフト紙からなる外皮材２で覆われているため、芯材１の強度が適度に保たれ、該芯材１の運搬や加工時の取り扱いがしやすくなる。尚、本実施形態では、外皮材２としてクラフト紙を用いる場合について説明したが、これに限定されず、不織布等を用いてもよく、要は通気性を有する材料であればよい。
【００６９】
また、図２における発泡治具４、５の治具内寸法は、所定の大きさの芯材１を一つの単位として、この芯材１を一つ分製造できる寸法に設定されているが、長さ方向に前記単位の倍数の大きさとなるようにしてもよい。この場合は、得られた芯材１を前記所定の大きさに切断することにより、真空断熱材に使用できる芯材１を一度に複数枚製造できるので、生産性の効率化が図れる。
【００７０】
また、発泡治具４、５の治具内寸法を厚さ方向で所定の寸法に設定し、一方幅方向および長さ方向で余裕をもたせた寸法としておき、この発泡治具４、５内部で所定の大きさの外皮材２に注入した発泡ウレタン原料３を発泡させることにより、ほぼ所定の大きさの芯材１を得ることができる。そして、外皮材２として長さ方向で前記所定の大きさの倍数となるものを用いることにより、前記所定の寸法を一つの単位とした場合、前記倍数分だけ長さ方向で複数の単位をもつ断熱材用芯材が一度に得られる。この場合も、この複数の単位からなる断熱材用芯材を所定の寸法に切断することにより、真空断熱材に使用できる芯材を一度に複数製造できるので、生産性の効率化が図れる。
【００７１】
さらに、クラフト紙等の通気性を有する材料を台等に広げて置き、該通気性を有する材料の上に発泡ウレタン原料を注ぎ、その後オーブン等に収容して通気性を有する材料や発泡ウレタン原料の周辺を所定の温度に保って発泡ウレタン原料を発泡させ、前記通気性を有する材料を残したまま所定の寸法に切削したウレタンフォームを芯材に用いて真空断熱材を製造してもよい。この場合は、従来方式のように発泡ウレタン原料を加熱せずに該発泡ウレタン原料を発泡させる場合に比べて、独立気泡の残留の少ないウレタンフォームの芯材が得られるため、フォーム廃材の量が減って、廃棄物処理等の環境上の問題がなく、コスト削減が可能な真空断熱材を提供できる。尚、前記台の代わりにベルトコンベアを用い、前記オーブンをトンネル状にすると、連続的に芯材を大量生産することができる。また、前記発砲ウレタン原料に、適当な気泡連通化剤を適量添加した場合であっても、上記と同様あるいはそれ以上の効果があることは明白である。
【００７５】
【発明の効果】
本発明では、発泡ウレタン原料を発泡治具に収容して加熱することより、発泡してできたウレタンフォームは、そのまま通気性を有する材料と共に断熱材用芯材として使用することができるため、加工の手間が省けるとともに、フォーム廃材が出ないので、処理コストのみならず廃棄物処理等の環境上でも問題のない断熱材用芯材が得られる。
【００７７】
また、発泡ウレタン原料を７５℃以上１３０℃以下の温度条件で発泡させることにより、特に独立気泡ができやすい表面のスキン部やその近くでも軟化状態を維持しながら発泡が進むので、該部位での独立気泡が破泡しやすくなり、連通気泡化が促進される。従って、ウレタンフォーム内部の全ての部位において、独立気泡の少なく連通気泡構造となるため、優れた品質の断熱材用芯材が得られる。
【００７８】
また、発泡ウレタン原料を発泡させる際に減圧することにより、特に独立気泡の残留しやすいスキン部やその近くも発泡中に外部から吸引されることにより独立気泡が破泡しやすくなり、連通気泡化が促進される。従って、ウレタンフォーム内部の全ての箇所において、独立気泡の少ない連通気泡構造となるため、優れた品質の断熱材用芯材が得られる。
【００８１】
また、通気性を有する材料としてクラフト紙を用い、その目付け量を５０〜１４０ｇ／ｍ²としたことにより、前記クラフト紙に適度な通気性をもたすことができるとともに、発泡前のウレタン原料が前記クラフト紙の外部への染み出すことによる発泡治具への張り付きもなく、しかも前記クラフト紙の硬さや強度が成型加工性に適しているため、独立気泡が少なく所望の形状をした断熱材用芯材が得られる。こうして得られた芯材の周囲はクラフト紙からなる外皮材で覆われているため、芯材の強度が適度に保たれ、該芯材の運搬や加工時の取り扱いがしやすくなる。
【００８３】
また、例えば発泡治具に凸部を設けておき、該凸部に通気性を有する材料に設けた穴や切り欠きを嵌合させたり、添わせたりすることにより、前記穴や切り欠きが位置決めの役割を果たすので、発泡ウレタン原料を注入した通気性を有する材料を発泡治具内の最適な位置に容易に収容することができるとともに、発泡治具内での前記通気性を有する材料の移動が阻止されるので、発泡ウレタン原料を発泡させて得られる断熱材用芯材の品質が安定する。
【００８５】
また、得られた芯材をそのままあるいは適当な大きさに切り出して真空断熱材に用いることができるため、加工の手間が省けるとともに、ウレタンフォーム廃材の出る量が減少し、廃棄物処理等の環境上の問題のない真空断熱材を低コストで提供できる。また、この真空断熱材は独立気泡の残留する部分の少ない連通気泡構造の芯材を用いているため、少量の吸着剤を併用することにより、長期間の使用による芯材内部からのガスの拡散に伴う経時的な断熱性能の劣化がほとんどない長寿命且つ高品質な真空断熱材となる。
【図面の簡単な説明】
【図１】（ａ）通気性を有する外皮材を筒状に丸めて下方の外皮材同士が重なった部分を接着した状態を示す斜視図である。
（ｂ）図１（ａ）に示す外皮材の両端の開口部の一方を閉じて接着した袋状の外皮材に発砲ウレタン原料を注入する時の斜視図である。
【図２】本発明の一実施例の断熱材用芯材の製造時の断面図である。
【図３】本発明の一実施例の発泡ウレタン原料を注入した外皮材を発泡治具に収容する時の一部省略斜視断面図である。
【図４】本発明の一実施例の断熱材用芯材の製造方法により作成された断熱材用芯材の側面断面図である。
【図５】図３におけるＡ−Ａ断面図である。
【図６】本発明の一実施例の真空断熱材の側面断面図である。
【図７】従来の硬質ウレタンフォームブロック製造時の断面図である。
【図８】従来の硬質ウレタンフォームパネルの斜視図である。
【図９】従来の真空断熱材の断面図である。
【符号の説明】
１芯材
２外皮材
２ａ開口部
２ｂ扁平部
３発泡ウレタン原料（発泡前）
３ａウレタンフォーム（発泡後）
４上治具
５下治具
６上チャンバ
７下チャンバ
８ヒータ
９気密空間
１０真空ポンプ
１１減圧ストックタンク
１２，１２ａパイプ
１３，１４バルブ
１５吸着材
１６テープ
１７外包材
１８真空断熱材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum heat insulating material used for a refrigerator, a freezer, and the like and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, for the purpose of improving the heat insulation performance of a vacuum heat insulating material, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-65990, a urethane foam obtained by foaming a urethane foam material is used as a core material, and this also has air permeability. Attention has been focused on a method for producing a vacuum heat insulating material, which is covered with an unsatisfactory resin film or the like and the inside thereof is decompressed and sealed. Hereinafter, the manufacturing method of the vacuum heat insulating material of Unexamined-Japanese-Patent No. 5-65990 is demonstrated with reference to FIGS.
[0003]
As shown in FIG. 7, a face material 26 made of air permeable paper or nonwoven fabric is placed on a gas permeable jig 25, and a foamed urethane raw material containing a cell communicating material is injected and foamed into the hard material. A urethane foam block 24 is obtained. Further, the rigid urethane foam block 24 is cut into an arbitrary size to obtain a rigid urethane foam panel 27 as shown in FIG. Then, this rigid urethane foam panel 27 is heated at a high temperature for a long time to evaporate adsorbed moisture and the like, and is covered with a container 23 made of a metal-plastic laminate film, and the inside is reduced in pressure and sealed, as shown in FIG. Such a vacuum heat insulating material 28 is obtained. The vacuum heat insulating material 28 manufactured in this manner has a high open cell ratio of the internal hard urethane foam panel 27 (core material), and therefore the heat insulating performance is hardly deteriorated over time even for long-term use. Absent.
[0004]
[Problems to be solved by the invention]
However, in the above conventional vacuum heat insulating material manufacturing method, in order to increase the open cell ratio, the foam connecting material is mixed with the cell connecting agent in the foamed urethane raw material, but when carried out industrially for mass production of urethane foam blocks, Depending on the type and amount of the cell communicating agent, many closed cells remain on the surface of the rigid urethane foam or in the vicinity of the skin, so the insulation performance when the urethane foam is processed into a vacuum insulation material decreases. In particular, there is a problem that the gas diffuses from the inside of the remaining closed cells over time due to the use for a long time (30 days or more), thereby increasing the internal pressure and deteriorating the heat insulation efficiency.
[0005]
Furthermore, since it is necessary to cut the urethane foam block and process it into a urethane foam panel, the number of work steps when manufacturing vacuum heat insulating materials increases, which not only increases labor and production costs, Since a large amount of processing dust is generated, there is a problem not only in terms of waste disposal cost but also in an environment such as wasteful resources.
[0006]
The present invention has been made in view of the above-mentioned conventional problems, and there is no environmental problem such as waste disposal, and it is intended to provide a vacuum heat insulating material whose performance is not deteriorated even for a long-term use. Objective.
[0013]
[Means for Solving the Problems]
  BookThe manufacturing method of the core material for heat insulating material of the invention covers the foamed urethane raw material with a material having air permeability and accommodates it in a foaming jig, foams the surroundings or the foaming jig at a predetermined temperature, and foams the predetermined material. Temperature of75 ℃ to 130 ℃InThe breathable material isolates the foamed urethane raw material from the foaming jig, and foams the foamed urethane raw material by reducing the pressure around the foamed urethane raw material.It is characterized by this.
[0014]
According to this configuration, during foaming of the foamed urethane raw material, foaming while maintaining the softened state by the heating action, especially the skin portion of the surface where the closed cells tend to remain, and the vicinity thereof tends to break, Communication bubble formation is promoted.
[0016]
According to this configuration, a heat insulating material core material having an open cell structure with few residual closed cells can be obtained.
[0020]
According to this configuration, during foaming of the foamed urethane raw material, the surface skin portion where the closed cells tend to remain, and the vicinity thereof foam while receiving the suction action due to the reduced pressure. Is promoted.
[0025]
  The material having air permeability is kraft paper, and the basis weight is 50 to 140 g / m.²It is characterized by being.
[0026]
According to this configuration, the breathable material has appropriate strength and moldability, and before the foamed urethane material is foamed, the foamed urethane material exudes to the outside of the kraft paper, which is a breathable material. There is no fear.
[0029]
  Also,PreviousThe air-permeable material is formed into a bag shape having an opening in at least one, and a hole or a notch is provided near the opening or in the other adhesive portion of the air-permeable material. .
[0030]
According to this configuration, for example, a protrusion is provided on the foaming jig, and the hole or notch is formed by fitting or attaching a hole or notch provided in the air-permeable material to the protrusion. Since the notch plays a role of positioning, it is easy to accommodate the air-permeable material in the foaming jig, and the movement of the air-permeable material in the foaming jig is prevented.
[0033]
  Further, the foaming jig is provided in an airtight space, or the inside of the foaming jig is an airtight chamber, and a branch path is provided in the middle of the path from the airtight space or the airtight chamber to a vacuum pump for decompressing, A pre-reduced decompression stock tank is connected to the branch path, and after the vacuum pump is driven, the foamed urethane raw material starts to foam, and at the timing when the generated bubbles break, A valve provided in the middle of the branch path is opened, and the pressure reduction is continued with the vacuum pump until foaming of the foamed urethane raw material is completed and cured to form urethane foam. Moreover, the core material for heat insulating materials of this invention was manufactured by the manufacturing method of one of said core materials for heat insulating materials.The vacuum heat insulating material of the present invention is the aboveRefusalThe heat-material core material is covered with an outer packaging material, and the inside is reduced in pressure and sealed.
[0034]
According to this configuration, the obtained core material can be cut as it is or can be cut into an appropriate size and used as a vacuum heat insulating material, so that processing work is saved and the amount of waste urethane foam material is reduced and discarded. It is possible to provide a vacuum heat insulating material free from environmental problems such as material processing at a low cost.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an outer skin material made of craft paper or the like having air permeability. First, the procedure for injecting the urethane foam raw material 3 into the outer skin material 2 will be described with reference to FIG. As shown to Fig.1 (a), the surface which mutually faces of the part which rolled the outer skin | cover material 2 into the cylinder shape and overlapped is adhere | attached. As a result, an adhesive portion 2 c extending in the length direction of the outer skin material 2 is formed at a substantially central portion of the bottom portion of the outer skin material 2. In addition,

openings

2 a and 2 a are formed at both ends of the outer skin material 2.
[0036]
Then, one opening 2a is closed and bonded as shown by the arrow in FIG. Thereby, as shown in FIG.1 (b), the substantially rectangular flat part 2b is formed in the skin material 2, and the skin material 2 becomes a bag shape by which the other opening part 2a was open | released. Next, an appropriate amount of the urethane foam raw material 3 is injected from the opening 2 a of the bag-shaped outer skin material 2. The foamed urethane raw material 3 is a mixed raw material composed of organic polyisocyanate, polyol, catalyst, foam stabilizer, and foaming agent, and is cured after firing to form urethane foam.
[0037]
Next, the structure of the apparatus which manufactures the core material for heat insulating materials which concerns on this invention is demonstrated. FIG. 2 is a cross-sectional view of the heat insulating material core according to an embodiment of the present invention when manufactured. In FIG. 2, 4 is an upper jig and 5 is a lower jig, which are attached to an upper chamber 6 and a lower chamber 7, respectively. An airtight space 9 is formed between the upper chamber 6 and the lower chamber 7, and the periphery of the upper jig 4 and the lower jig 5 in the airtight space 9 is covered with a heat-resistant insulator. A heater 8 made of an electric heating element having flexibility is disposed. The heater 8 may be embedded in the upper jig 4 or the lower jig 5.
[0038]
Reference numeral 10 denotes a vacuum pump, and the vacuum pump 10 and the airtight space 9 are communicated with each other by a pipe 12. A decompression stock tank 11 is connected to a pipe 12a branched from the middle of the pipe 12, and the decompression stock tank 11 and the airtight space 9 are communicated with each other by the

pipes

12 and 12a. Further,

valves

13 and 14 are provided on the side of the airtight space 9 from the branch point of the pipe 12 and on the pipe 12a branched from the branch point, respectively, and the airtight space 9, the vacuum pump 10 and the decompression stock tank 11 are connected to each other. In order to open or close the communication, these

valves

13 and 14 are opened and closed as necessary. The decompression stock tank 11 is decompressed in advance by the vacuum pump 10, and the

valves

13 and 14 are closed in this state.
[0039]
The upper jig 4 and the lower jig 5 are each provided with a plurality of

jig openings

4a and 5a that are formed through holes and communicate with the pipe 12, and the openings 2a and flat portions 2b of the outer skin material 2.

Jig sealing portions

4b and 5b for sandwiching and fixing are provided. Instead of providing the

jig openings

4a and 5a in the foam jigs 4 and 5 respectively, the foam jigs 4 and 5 themselves may be made of a material having air permeability such as a ceramic foam.
[0040]
In addition, in the thin portion of the foamed urethane raw material 3 injected into the outer skin material 2, the firing

jigs

4, 5 are reduced by reducing the amount of heat generated by the heater 8 or roughening the heater distribution. You may make it adjust the quantity of heat transmitted to each part of the inside according to temperature conditions required for this part. Furthermore, temperature sensing means are provided at several locations in the vicinity of the shell material 2 of the firing

jigs

4 and 5, and the amount of heat generated by the heater 8 is locally adjusted based on the temperature information sensed by the temperature sensing means. May be. Thereby, the heat of the heater 8 is appropriately transmitted over the entire foamed urethane raw material 3 in the outer skin material 2, and the foamed urethane raw material 3 can be stably foamed. Further, instead of the heater 8, a heated liquid such as water or oil or a gas such as steam or air passed through the pipe may be used.
[0041]
A procedure for manufacturing the heat insulating material core using the apparatus configured as described above will be described. First, the outer skin material 2 is placed so that the opening 2a and the flat portion 2b of the outer skin material 2 (see FIG. 1B) in which the urethane foam raw material 3 is injected into the jig sealing portion 5b of the lower jig 5 rides up. Is placed on the lower jig 5. Then, by setting the upper chamber 6 to which the upper jig 4 is attached to the lower chamber 7, the outer skin material 2 is accommodated in the firing jigs 4 and 5. Thereby, since the opening 2a and the flat part 2b are respectively sandwiched by the

jig sealing parts

4b and 5b until the foaming reaction is completed and the foamed urethane raw material 3 is cured, the foamed urethane raw material 3 does not enter. It becomes flat. Therefore, this flat part 2b can be easily bent after the preparation of the core material 1 is completed.
[0042]
And the connection location of the said upper chamber 6 and the lower chamber 7 is sealed in the state which can be attached or detached by an O-ring etc., and the inside is set to an airtight state. Further, instead of the airtight space 9, the

jig openings

4a and 5a of the upper jig 4 and the lower jig 5 are directly connected to the pipe 12, and the periphery of the jig including the vicinity of the

jig sealing portions

4b and 5b. If the portion in which the core material 1 is accommodated is an airtight chamber, a pressure reducing action similar to the above can be expected without the upper chamber 6 and the lower chamber 7, and the equipment can be further downsized. Further, in FIG. 2, the chamber is opened in the vertical direction. However, when this portion is rotated by 90 ° and the chamber is opened in the horizontal direction, the apparatus does not take up more installation space.
[0043]
Further, as shown in FIG. 3, a convex portion 5c is provided on the jig sealing portion 5b of the lower jig 5, and the convex portion 5c is passed through the hole 2d formed in the flat portion 2b of the outer skin material 2 and By fitting the convex portion 5c into the concave portion 4c provided at a position facing the convex portion 5c of the jig 4, the outer skin material 2 can be easily accommodated at an optimal position inside the firing

jigs

4 and 5. In addition, once the outer skin material 2 is accommodated in the foaming

jigs

4 and 5, significant movement of the outer skin material 2 inside the foaming

jigs

4 and 5 is prevented. The foaming reaction of 3 can always be carried out stably and under the same conditions. FIG. 3 shows a case in which the hole 2d is provided in the flat part 2b of the outer skin material 2. Instead of the hole 2d, a notch for positioning is inserted, and this notch is formed in the convex part 5c. You may make it accompany. Further, a positioning hole or notch may be provided near the opening 2 a of the outer skin material 2.
[0044]
Then, if the play to the convex portion 5c is provided in the notch or the hole near either the opening portion 2a or the flat portion 2b in a direction perpendicular to the opening portion 2a, the outer skin material 2 is further cured. It becomes easy to set the tool 5. Also, the asobi is necessary for the displacement of the outer skin material 2 when the length of the outer skin material 2 is insufficient in the direction perpendicular to the opening 2a due to the firing of the foamed urethane raw material. It has become. Furthermore, the clamping force of the outer shell material 2 of the

jig sealing portions

4b and 5b on the side where the deviation of the outer shell material 2 is necessary is such that the outer shell material 2 is displaced. The upper jig 4 and the lower jig 5 near the core material 1 other than the

jig sealing portions

4b and 5b have a small gap so as not to sandwich the outer skin material 2 when the upper chamber 6 is set in the lower chamber 7. It is good to keep.
[0045]
The upper jig 4 and the lower jig 5 are preheated to a predetermined temperature by the heater 8, and are set to maintain the predetermined temperature at least until the foaming reaction of the urethane foam raw material 3 is completed. . In this state, after the upper chamber 6 is set in the lower chamber 7, the vacuum pump 10 is driven to open the valve 13. And the foaming urethane raw material 3 starts foaming, and the valve 14 is opened at the timing when the generated bubble breaks. In this state, the valve 13 is opened until the foaming of the foamed urethane raw material 3 is completed, and the inside of the airtight space 9 is continuously depressurized by the vacuum pump 10. When foaming of the foamed urethane raw material 3 is completed and cured to become the urethane foam 3a, the inside of the airtight space 9 is returned to atmospheric pressure. Then, the upper chamber 6 is removed from the lower chamber 7, and the core material 1 composed of the outer skin material 2 and the urethane foam 3a therein is taken out.
[0046]
4 is a side cross-sectional view of the core member, and FIG. 5 is a cross-sectional view taken along line AA in FIG. In these drawings, reference numeral 1a denotes a depressed portion, and the depressed portion 1a is pressed against a substantially rectangular protruding portion 4c provided on the upper jig 4 when the foamed urethane raw material 3 expands while foaming. As a result, the shape of the protrusion 4c is reflected to form a rectangular shape. Further, 1b and 1c are corner portions on the periphery of the core material 1. The corner portions 1b and 1c are formed on the corner portions 1b and 1c inside the firing

jig

4 and 5 when the foamed urethane raw material 3 is foamed. A curved surface is created by following the rounded shape of the corresponding part. That is, the upper jig 4 and the lower jig 5 are formed so that all corner portions including the concave portion of the core material 1 have an appropriate curved surface.
[0047]
Moreover, in the space for accommodating the core material 1 formed by the upper jig 4 and the lower jig 5, the dimension in the thickness direction needs to be such that the core material 1 has a predetermined thickness. When the strength of the outer skin material 2 overcomes the foaming force of the urethane foam raw material 3, the corner portions of the upper jig 4 and the lower jig 5 corresponding to the vicinity of the corner portions of the core material 1 such as the corner portions 1b and 1c are cored. The gap may be formed in a shape with a small radius of curvature different from the curved surface of the material 1. In some cases, the foaming may be performed even if the corner portions of the upper jig 4 and the lower jig 5 are squared. If the urethane raw material 3 is in a state after being foam-cured, and if there is a dimensional relationship between the corner portions of the foaming

jigs

4 and 5 and the outer skin material 2, the corner portion of the core material 1 is finished into a curved surface. .
[0048]
In addition, by always providing a gap between the outer skin material 2 and the inside of the firing

jigs

4 and 5 in this manner, suction by the vacuum pump 10 can be promoted when the foamed urethane raw material 3 is foamed. That is, since a pressure reduction effect over a wide range can be obtained in a short time, the open cell structure inside the urethane foam 3a can be made more uniform and low density.
[0049]
As shown in FIG. 1, the outer skin material 2 has an adhesive portion 2c extending in the length direction at a substantially central portion of the bottom portion. This adhesive portion 2c is formed by cylindrically attaching the outer skin material 2 made of kraft paper or the like. The inner side may be overlapped and bonded to each other, folded in the vicinity of the adhesive base, and folded to one side, and this adhesive surface is attached to at least one end in the length direction or width direction of the core material. It may be provided. In this case, when the foamed urethane raw material 3 is injected into the inner surface side of the outer skin material 2, the entire circumference of the outer skin material 2 in contact with the foamed urethane raw material 3 becomes a single surface with good air permeability at least until just before the completion of the firing. Open air bubbles are more uniformly formed in the later urethane foam 3a. Further, mass productivity is improved by attaching a heat-weldable plastic in advance to the outer skin material 2 in the vicinity of the bonding portion as described above and bonding it by hot pressing with a roller or the like.
[0050]
Further, when the core material 1 that has been hardened after foaming has unnecessary protrusions and edges, the protrusions can be formed by tapping them with a hammer or the like and pressing them with a pressing die or jig to make them curved, flat, or concave. There is no possibility that the outer packaging material of the vacuum heat insulating material, which will be described later, is torn at the portion or the edge portion. Moreover, you may form the corner part of the above core materials 1 in C surface shape. Incidentally, by providing a gap or groove between the curved surface of the corner portion of the core material 1 and the corresponding corner portions of the upper jig 4 and the lower jig 5, this area becomes a pressure reducing passage, and an even faster time Thus, the pressure can be reduced over a wide range and evenly, and the communication bubbles in the core material 1 can be made more uniform and low in density efficiently.
[0051]
FIG. 6 is a side cross-sectional view of a vacuum heat insulating material according to an embodiment of the present invention. In FIG. 6, 15 is an adsorbent for adsorbing and removing a small amount of gas or moisture generated from the inside of the core material 1 or entering from the outside of the vacuum heat insulating material 18, and the adsorbent 15 has air permeability. The adhesive tape 16 is sealed in the depressed portion 1a. Reference numeral 17 denotes an outer packaging material made of a gas barrier material (for example, a non-breathable thin film made of a laminate of an aluminum-deposited polyester film and a metal foil heat-weldable plastic).
[0052]
The procedure for producing the vacuum heat insulating material 18 having such a configuration will be described. The

flat portions

2b and 2b at both ends of the outer skin material 2 of the core material 1 manufactured by the above method are bent upward from the root, and the outer skin as shown in the figure. After fixing with an adhesive tape or the like so as to be in close contact with the outer peripheral surface of the material 2, the core material 1 is accommodated in a drying furnace at 120 to 130 ° C. for about 2 hours, and moisture and gas of the urethane foam 3 a inside the core material 1 are stored. Is evaporated to dryness. Then, an appropriate amount of the adsorbent 15 is injected into the depressed portion 1a of the core material 1 taken out from the drying furnace, and then sealed with the tape 16 so as to cover the entire depressed portion 1a to obtain a core material assembly. Furthermore, the core assembly is packed in an outer packaging material 17 formed in a bag shape having an opening 17a at one end, and the inside of the outer packaging material 17 is decompressed in a vacuum tank to thermally seal the opening 17a. A vacuum heat insulating material 18 in which the core assembly is sealed in the outer packaging material 17 is obtained.
[0053]
In addition, as shown in FIG. 6, since the opposite side can be made into a flat surface by bending the flat part 2b to the side where the depressed part 1a of the outer skin material 2 is formed, the obtained vacuum It becomes easy to affix the heat insulating material 18 to inner side plane parts, such as the outer wall material of a refrigerator. In addition, if the foamed urethane raw material 3 is foam-cured and then a hole or notch is provided in the outer skin material 2 of the core material 1, moisture or gas of the urethane foam 3a is easily released to the outside directly from the hole or notch. Therefore, the time required for putting the core material 1 into a drying furnace and drying it, or wrapping the core material assembly with the outer packaging material 17 and evacuating the inside thereof can be shortened. Further, the vicinity of the opening 2a of the core material 1 and the flat

flat portions

2b and 2b of the adhesive portion may be removed and used for the core material 1, and the vicinity of the opening 2a and the flat portion 2b may be used as the outer shell material. 2 may be bonded after being folded back so as not to be sandwiched between the

jig sealing portions

4b and 5b, and a flat portion may not be formed in this portion.
[0054]
Also, if there is a convex part on the inside of the outer wall material to which the vacuum heat insulating material such as a refrigerator is attached, and the condensation pipe is attached to that part, the thickness of the outer packaging material on the core material of the vacuum heat insulating material on that side For example, if a protrusion is provided on the foaming jig so as to form a recess corresponding to the protrusion or a recess away from the region with the protrusion, the core material can be easily removed without producing cutting waste. The concave portion can be formed.
[0055]
Now, the dimension in the jig is 440 × 700 × 15 (mm), and the basis weight is 80 g / m as the outer skin material 2.²The core material 1 was manufactured by foaming and curing the foamed urethane raw material 3 under various conditions shown in Table 1 below. By the way, as an index for evaluating the quality of the urethane foam 3a obtained by foaming the foamed urethane raw material 3, the degree of openness of the open cells defined by the following formula is usually used. The openness value is also shown in Table 1.
Opening degree (%) = (V−Q) / V × 100 (1)
Here, V is a spatial volume (cc) in the heat insulating material, and Q is a generated gas volume (cc) in the heat insulating material. Also,
Q = (P1-P0) × V / 760
Holds. Here, P0 is the initial pressure (Torr) in the heat insulating material, and P1 is the pressure (Torr) after 24 hours in the heat insulating material.
[0056]
When the degree of openness defined by the above formula (1) is a low value, there are many closed cells remaining particularly at or near the skin portion which is the surface of the urethane foam 3a. When used as the core material 1 of the vacuum heat insulating material 18 as it is, the residual gas in the closed cells is filled in the vacuum heat insulating material 18 and the degree of vacuum is lowered, and the heat insulating performance is deteriorated from the initial stage of using the vacuum heat insulating material. It can be seen.
[0057]
[Table 1]

[0058]
When the injection amount of the foamed urethane raw material 3 is 363 g, the temperature of the upper jig 4 and the lower jig 5 is set to 30 ° C., and the foamed urethane raw material 3 is foamed without reducing the pressure in the airtight space 9, The filling of the urethane foam 3a in the

jigs

4 and 5 is incomplete, the degree of openness is as low as 89.5%, and many closed cells remain in and near the skin of the urethane foam 3a. The portion that can be used as the vacuum heat insulating material 18 was about 50% of the entire core material 1.
[0059]
Further, when the foamed urethane raw material 3 is foamed under the same conditions as described above except that the amount of the foamed urethane raw material 3 injected is 282 g and the inside of the airtight space 9 is depressurized, the foamed urethane raw material 3 is placed in the upper jig 4 and the lower jig 4. The entire foam in the jig 5 is foamed, and the urethane foam 3a is completely filled, but the openness of the open cells is still low at 92.1%, and there are still closed cells in the skin of the urethane foam 3a and its vicinity. Although the portion that can be used as the vacuum heat insulating material is only about 60% of the entire core material 1, the proportion of the portion that can be used as the vacuum heat insulating material 18 is slightly improved due to the reduced pressure in the airtight space 9. did.
[0060]
That is, when foaming the foamed urethane raw material 3 in the upper jig 4 and the lower jig 5, the inside of the airtight space 9 is reduced in pressure, so that the skin part where the closed cells are likely to remain and the vicinity thereof are also externally exposed during foaming. Since the closed air bubbles are easily broken and the formation of the open air bubbles is promoted, the urethane foam 3a with few remaining portions of the closed air bubbles can be obtained. Moreover, even if the injection amount of the foamed urethane raw material 3 is reduced as much as 81 g, the urethane foam 3a is completely filled inside the firing

jigs

4 and 5, and the low density of the urethane foam 3a is reduced due to reduced pressure. Since the core material 1 is obtained from the raw material, the amount of foam waste can be reduced by that amount, and a vacuum heat insulating material that has almost no environmental problems such as waste disposal can be provided at low cost.
[0061]
Further, when the foamed urethane raw material 3 is foamed under the same conditions as described above except that the jig temperature of the upper jig 4 and the lower jig 5 is 75 ° C., the foamed urethane raw material 3 The entire foam in the jig 5 was foamed, and the urethane foam 3a was completely filled, and the degree of openness of the communicating bubbles was improved to 99.8%. Thereby, the part which the independent bubble remained hardly disappeared, and the core material 1 which can be used as the 100% vacuum heat insulating material 18 is obtained when the adsorbent 15 is used together in an appropriate amount.
[0062]
That is, by reducing the pressure in the hermetic space 9 and maintaining the jig temperature at 75 ° C., the closed cell where the closed cells are likely to remain, especially in the vicinity of the closed cell by the suction action from outside and the softening action by heating during foaming Is easy to break, and the formation of open cells is promoted, so that the core material 1 having the open cell structure without the closed cells remaining in almost all places can be obtained. Since the core material 1 can be processed into the vacuum heat insulating material 18 as it is, there is no need to cut out a core material of a predetermined size from the urethane foam block as in the prior art, and the processing work is saved correspondingly, and the waste foam material is generated. Therefore, it is possible to provide a vacuum heat insulating material capable of reducing costs without causing environmental problems such as waste disposal.
[0063]
Further, when the foamed urethane raw material 3 is foamed under the same conditions as described above except that the jig temperature of the upper jig 4 and the lower jig 5 is 110 ° C., the degree of openness of the open cells is 99.9%. In this case, the core material 1 that can be used for the 100% vacuum heat insulating material 18 was obtained by using the adsorbent 15 together.
[0064]
And when the jig temperature of the upper jig 4 and the lower jig 5 is set to 55 ° C., the open degree of the communicating bubbles becomes 99.1%, and the closed cell of the urethane foam 3a and the vicinity thereof has no closed cells. Although there is a little residue, by removing this portion, the portion that can be used as the vacuum heat insulating material 18 is about 85% of the entire core material 1, and the amount of waste material is considerably reduced.
[0065]
By warming the foaming jig until foaming of the foamed urethane raw material 3 is completed in this way, the raw material foams while maintaining softening, especially at or near the skin portion where the closed cells are likely to remain. Since urethane foam 3a with less residual of closed cells can be obtained, the amount of foam waste material is considerably reduced compared to the conventional method, and the effect is prominent when the jig temperature is 55 ° C or higher, particularly 75 ° C or higher. In this case, the core material 1 that can be used as the almost 100% vacuum heat insulating material 18 is obtained by using an appropriate amount of adsorbent. The upper limit of the jig temperature is 140 ° C. due to the heat resistance of the urethane material, and the upper limit needs to be 130 ° C. in consideration of the quality variation when industrially implemented.
[0066]
Further, the basis weight of the outer skin material 2 is 50 g / m.²When less than kraft paper is used, a part of the foamed urethane raw material before foaming penetrates into the kraft paper and leaks to the outside of the kraft paper, which acts like an adhesive and after the urethane raw material is foamed and cured, the core material 1 Stuck to the foaming

jigs

4 and 5, making it difficult to remove the core material 1 from the foaming

jigs

4 and 5.
[0067]
And the weight of the outer skin material 2 is 140 g / m.²When the kraft paper exceeding 1 is used, the outer shell material 2 becomes hard, so that the moldability is inferior, and it becomes difficult to follow the shape in the jig, so that the core material 1 having a desired shape cannot be obtained. Further, since the air permeability of the outer skin material 2 is also deteriorated, there is a problem that the pressure reducing effect at the time of manufacturing the core material 1 is lowered and the high quality core material 1 with few closed cells cannot be obtained.
[0068]
That is, the basis weight of the outer skin material 2 is 50 to 140 g / m.²By using this kraft paper, it is possible to give the kraft paper an appropriate air permeability, and there is no sticking to the foaming

jigs

4 and 5 due to the exudation of the urethane raw material 2 before the foaming to the outside. Moreover, since the hardness and strength of the kraft paper are suitable for molding processability, the core material 1 having a desired shape can be easily obtained. Since the periphery of the core material 1 obtained in this way is covered with the outer skin material 2 made of kraft paper, the strength of the core material 1 is maintained moderately, and the core material 1 can be easily transported and handled during processing. . In the present embodiment, the case of using kraft paper as the outer skin material 2 has been described. However, the present invention is not limited to this, and a nonwoven fabric or the like may be used.
[0069]
In addition, the dimensions in the jigs of the foaming

jigs

4 and 5 in FIG. 2 are set to dimensions that allow the core material 1 to be manufactured by one unit, with the core material 1 having a predetermined size as one unit. You may make it become the magnitude | size of the multiple of the said unit in the length direction. In this case, by cutting the obtained core material 1 into the predetermined size, a plurality of core materials 1 that can be used as a vacuum heat insulating material can be manufactured at a time, so that productivity can be improved.
[0070]
In addition, the dimensions in the jigs of the foaming

jigs

4 and 5 are set to predetermined dimensions in the thickness direction, and the dimensions are provided with allowances in the width direction and the length direction. By foaming the foamed urethane raw material 3 injected into the skin material 2 having a predetermined size, the core material 1 having a substantially predetermined size can be obtained. Then, by using the outer skin material 2 that is a multiple of the predetermined size in the length direction, when the predetermined dimension is set as one unit, it has a plurality of units in the length direction by the multiple. A core material for heat insulation can be obtained at a time. Also in this case, by cutting the core material for heat insulating material composed of a plurality of units into a predetermined size, a plurality of core materials that can be used for the vacuum heat insulating material can be manufactured at a time, so that productivity can be improved.
[0071]
Further, spread a breathable material such as kraft paper on a table and the like, pour urethane foam raw material on the breathable material, and then store it in an oven or the like to have a breathable material or urethane foam raw material A vacuum heat insulating material may be produced by foaming a foamed urethane raw material while maintaining the surrounding area at a predetermined temperature, and using urethane foam cut into a predetermined size while leaving the air-permeable material as a core material. In this case, since the core material of urethane foam with less residual of closed cells is obtained compared to the case of foaming the urethane foam material without heating the foamed urethane material as in the conventional method, the amount of foam waste material is reduced. Thus, there can be provided a vacuum heat insulating material that can be reduced in cost without causing environmental problems such as waste disposal. In addition, if a belt conveyor is used instead of the stand and the oven is formed in a tunnel shape, the core material can be continuously mass-produced. Further, it is obvious that even when an appropriate amount of a cell communicating agent is added to the foamed urethane raw material, the same effect as described above or more.
[0075]
【The invention's effect】
  In the present inventionSince the foamed urethane foam is housed in a foaming jig and heated, the foamed urethane foam can be used as it is as a core material for a heat insulating material together with a breathable material. In addition to being able to save, no foam waste material is produced, so that a core material for a heat insulating material can be obtained which has no problem not only in the processing cost but also in the environment such as waste disposal.
[0077]
  AlsoThe foamUrethane raw materials are emitted at a temperature of 75 ° C or higher and 130 ° C or lower.foamThis makes it possible to generate soft cells while maintaining a softened state at or near the skin where the closed cells tend to form.foamTherefore, it becomes easy for the closed cells at the part to break, and the formation of connected bubbles is promoted. Accordingly, since all the parts inside the urethane foam have a closed cell structure with few closed cells, an excellent quality core material for heat insulating material can be obtained.
[0078]
  When foaming urethane foam materialsReduced toBy pressing, especially the skin portion where the closed cells are likely to remain and the vicinity thereof are sucked from the outside during the foaming, so that the closed cells are easily broken and the formation of open cells is promoted. Therefore, since it becomes the open cell structure with few closed cells in all the places inside a urethane foam, the core material for heat insulating materials of the outstanding quality is obtained.
[0081]
  Also, ThroughKraft paper is used as the tempering material, and the basis weight is 50 to 140 g / m.²As a result, the kraft paper can have an appropriate air permeability, and the urethane raw material before foaming does not stick to the foaming jig due to the outside of the kraft paper. Since the hardness and strength of kraft paper are suitable for molding processability, a core material for a heat insulating material having a desired shape with few closed cells can be obtained. Since the periphery of the core material obtained in this way is covered with the outer cover material made of kraft paper, the strength of the core material is kept moderate, and the core material can be easily transported and handled during processing.
[0083]
  Also, ExampleFor example, a convex part is provided in the foaming jig, and the hole or notch is used for positioning by fitting or attaching a hole or notch provided in the air-permeable material to the convex part. To fulfillfoamA breathable material infused with urethane material is developed.foamIt can be easily stored in the optimal position in the jig andfoamSince the movement of the air-permeable material in the jig is prevented, the quality of the insulating material core material obtained by foaming the foamed urethane raw material is stabilized.
[0085]
  AlsoGetThe core material can be cut as it is, or cut into an appropriate size and used as a vacuum heat insulating material, which saves labor and reduces the amount of waste urethane foam, resulting in environmental problems such as waste disposal. Can provide vacuum insulation without any cost. In addition, since this vacuum heat insulating material uses a core material with an open cell structure with few closed cells remaining, by using a small amount of adsorbent together, gas diffusion from inside the core material over a long period of time can be achieved. Thus, it becomes a long-life and high-quality vacuum heat insulating material with almost no deterioration in heat insulating performance with time.
[Brief description of the drawings]
FIG. 1 (a) is a perspective view showing a state in which an outer skin material having air permeability is rolled into a cylindrical shape and a portion where lower skin materials overlap each other is bonded.
(B) It is a perspective view when inject | pouring a foaming urethane raw material into the bag-like outer skin material which closed and adhered one side of the opening part of the both ends of the outer skin material shown to Fig.1 (a).
FIG. 2 is a cross-sectional view of a heat insulating material core according to an embodiment of the present invention when manufactured.
FIG. 3 is a partially omitted perspective cross-sectional view when the outer skin material into which the foamed urethane raw material of one embodiment of the present invention is injected is accommodated in a foaming jig.
FIG. 4 is a side cross-sectional view of a heat insulating material core produced by the method for manufacturing a heat insulating material core according to an embodiment of the present invention.
FIG. 5 is a cross-sectional view taken along the line AA in FIG.
FIG. 6 is a side sectional view of a vacuum heat insulating material according to an embodiment of the present invention.
FIG. 7 is a cross-sectional view of the conventional rigid urethane foam block during manufacture.
FIG. 8 is a perspective view of a conventional rigid urethane foam panel.
FIG. 9 is a cross-sectional view of a conventional vacuum heat insulating material.
[Explanation of symbols]
1 Core material
2 Skin material
2a opening
2b Flat part
3 Raw materials for urethane foam (before foaming)
3a Urethane foam (after foaming)
4 Upper jig
5 Lower jig
6 Upper chamber
7 Lower chamber
8 Heater
9 Airtight space
10 Vacuum pump
11 Depressurized stock tank
12,12a pipe
13,14 Valve
15 Adsorbent
16 tapes
17 Outer packaging material
18 Vacuum insulation

Claims

Covering the material with the urethane foam material having air permeability accommodated for foaming jig, surrounding or the foam jig was a foamed maintained at a predetermined temperature, the predetermined temperature is Ri der 75 ° C. or higher 130 ° C. or less ,
The air-permeable material isolates the foamed urethane raw material from the foaming jig, and the foamed urethane raw material is depressurized and foamed by separating the air-permeable material. Manufacturing method of core material.

It said material having gas permeability is kraft paper, the manufacturing method of the heat insulating material for a core material according to claim 1 in which the basis weight is characterized in that it is a 50~140g / m ^2.

Claim 1, wherein the material having air permeability and a bag shape having an opening on at least one, provided outs holes or cut into the other adhesive portion of the material having the opening or near the breathable Or the manufacturing method of the core material for heat insulating materials of Claim 2 .

The foaming jig is provided in an airtight space, or the inside of the foaming jig is an airtight chamber,
A branch path is provided in the middle of the path from the airtight space or the airtight chamber to the vacuum pump for performing pressure reduction, and a decompression stock tank previously depressurized is connected to the branch path,
After driving the vacuum pump, the foamed urethane material starts to foam, and at the timing when the generated bubbles break, the valve provided in the middle of the branch path is opened,
The method for producing a core material for a heat insulating material according to any one of claims 1 to 3, wherein decompression is continued with the vacuum pump until foaming of the foamed urethane raw material is completed and cured to form urethane foam. .

A heat insulating material core material produced by the method for producing a heat insulating material core material according to any one of claims 1 to 4.

A vacuum heat insulating material, wherein the core material for heat insulating material according to claim 5 is covered with an outer packaging material, and the inside is sealed under reduced pressure.