JP3700865B2

JP3700865B2 - Thermal insulation for waterproof sheet construction

Info

Publication number: JP3700865B2
Application number: JP16862695A
Authority: JP
Inventors: 達也小野; 正男徳田
Original assignee: THE FURUKAW ELECTRIC CO., LTD.
Current assignee: THE FURUKAW ELECTRIC CO., LTD.
Priority date: 1995-07-04
Filing date: 1995-07-04
Publication date: 2005-09-28
Anticipated expiration: 2015-07-04
Also published as: JPH0911381A

Description

【０００１】
【産業上の利用分野】
本発明は、ビルなどの建築物の屋上コンクリートなどに、断熱及び防水の目的で施すシート防水工法に用いる断熱材及びそれに用いる架橋ポリオレフィン発泡シートの製造方法に関するものである。
【０００２】
【従来技術】
シート防水工法とは、例えばコンクリート造りの建築物の屋上に接着剤により樹脂発泡シートなどの断熱材、塩化ビニル樹脂（以下塩ビと略称する）、エチレンプロピレンジエン系ゴム（ＥＰＤＭ）などからなる防水シートを順次貼り付けて建築物の防水化と断熱化を行う工法である。
【０００３】
従来のシート防水工法を塩ビ製防水シートの場合で具体的に例示すると、建築物の屋上のコンクリート下地にスチレンブタジエンゴム（ＳＢＲ）系やニトリルゴム（ＮＢＲ）系などのゴム系接着剤を２５０ｇ／ｍ²程度塗布し乾燥させる工程、次にこの上に、厚さ１０〜５０ｍｍ程度で、発泡倍率２０〜３０倍程度のポリエチレン発泡シートの片面にロール刷毛などを使用してクロロプレンゴム（ＣＲ）系接着剤を２５０ｇ／ｍ²程度塗布し、十分なオープンタイムをとった後、この接着剤塗布面を貼り付ける工程、その後、さらにこの発泡シート上にロール刷毛などを用いてＣＲ系接着剤を塗布し、十分なオープンタイムをとった後、厚さ２ｍｍ程度の塩ビシートにＮＢＲ系接着剤を同様に塗布し十分オープンタイムをとった状態のものを貼り付ける工程からなっている。
【０００４】
ここで、この防水シート工法においては、強風時に屋上に負圧が生じ、この負圧がシートへの剥離力となって作用するため、少なくともシート間の接着力は１ｋｇ／２５ｍｍ以上、好ましくは１．５ｋｇ／２５ｍｍ以上であることが必要とされている。
【０００５】
【発明が解決しようとする課題】
上記したように、従来のシート防水工法では、接着剤の塗布回数が多く且つ複数種の接着剤を使用し、しかも現場作業であるため、その作業は煩雑を極めた。また、現場で接着剤を塗工する作業は、接着剤にトルエン、アセトン等の溶剤が含まれているために、引火のおそれがあり、樹脂発泡シートの性質上、接着剤塗布にロール刷毛等を使用すると、静電気が発生し、この放電により溶剤に引火する事故が発生しており、静電気の発生しない工法が求められていた。
【０００６】
さらに、接着剤の塗工は、下地のコンクリート面、断熱材である樹脂発泡シートの表裏面、防水シート面の計４面に施す必要があり、屋上の限られたスペースのなかで、接着剤を塗布した面を乾燥するためのオープンタイムの間接着剤を塗布したシートを広げておく必要があった。この間に雨が降ったり、強風が吹くと作業ができないため、天候の状況を予想しながら作業しなければならず、工期の進捗管理上大きな問題があった。
【０００７】
このため、近時においては、あらかじめ工場で樹脂発泡シートの表面にＣＲ系接着剤を塗布、乾燥させた接着剤付き樹脂発泡シートを作製し、これを施工現場に持ち込み、コンクリート下地面及び塩ビシート面に貼り合わせる方法の確立が急がれている。
【０００８】
ところで、シート防水工法用の断熱材として耐溶剤性が良いため好んで使用される架橋ポリオレフィン発泡シートには、化学架橋法及び電子線架橋法の２通りの製造方法があり、それぞれに欠点を有していた。
すなわち、化学架橋法による架橋ポリオレフィン発泡シートは、ポリオレフィンに架橋剤および熱分解型の発泡剤を配合した組成物を架橋剤および発泡剤の分解温度以下の温度で溶融押出成形した母板シートを、加熱炉中で架橋発泡させて得られる。この発泡シート表面は表皮膜厚さが２０〜３０μｍあり、接着剤の凝集力が十分に大きければ、１．５ｋｇ／２５ｍｍ以上の接着力を発揮するものであるが、表面の凹凸が大きく、予め塗布する接着剤の塗布量は少なくとも１００ｇ／ｍ²、好ましくは２００ｇ／ｍ²以上必要であった。ところが、一般的な接着剤の塗工設備では、多くても５０ｇ／ｍ²程度しか塗工することができないので、化学架橋ポリオレフィン発泡シートを断熱材として使用する場合は現場で接着剤の厚塗りが可能なロール刷毛などによる塗工作業を行わざるを得なかった。
【０００９】
一方、電子線架橋法による架橋ポリオレフィン発泡シートは、ポリオレフィンに熱分解型の発泡剤を配合した組成物を発泡剤の分解温度以下で溶融押出成形した母板シートに電子線照射をして架橋させ、その後加熱炉中で発泡させて得られる。この発泡シートの表皮は表皮膜厚さは８〜１２μｍと薄く、表面が平滑であるために、予め塗布する接着剤の塗布量は２５ｇ／ｍ²以上あれば材料破壊するに十分な接着力に到達するが、表皮下の発泡層の架橋度が十分に高くないこと及び表皮膜厚さの薄いことに起因して材料破壊強度（表皮強度）が低いため、０．７〜１ｋｇ／２５ｍｍ程度の接着力（材料破壊）しか得られず、強風時の負圧に耐えないことからシート防水工法用断熱材として使用するには難点があった。
【００１０】
そこで、本発明は、シート防水工法における上記した種々の問題を解決し、現場での接着剤塗工作業をできるだけ少なくし、且つ接着剤の総使用量を少なくするとともに、断熱材貼付の作業性を著しく改善することができ、強風時の負圧にも耐えるシート防水工法のための断熱材及びそれに用いる架橋ポリオレフィン発泡シートの製造方法を提供することを目的とする。
【００１１】
【課題を解決するための手段】
上記目的を達成するために、本発明においては、架橋ポリオレフィン発泡シートの両面に接着剤層が設けられ、少なくともその一方の接着剤層上には両面離型性を有する離型フィルムが貼付されているシート防水工法用断熱材において、前記架橋ポリオレフィン発泡シートは架橋・発泡前の化学架橋剤配合の母板シートの両表面に加速電圧１５０〜３００ｋＶ、照射線量１０〜１５０ｋＧｙの条件下で電子線照射を行って表面近傍のみを電子線架橋させた後、加熱して全体を化学架橋させるとともに発泡させることにより得られ、前記前記架橋ポリオレフィン発泡シートは平均厚さ２０μｍ以上の緻密な表皮層を両面に有し、且つ表皮近傍の材料破壊強度が１．５ｋｇ／２５ｍｍ以上であり、さらに表皮表面の凹凸の山と谷の平均高低差が２００μｍ以下の平滑性を有することを特徴とするシート防水工法用断熱材が提供される。
【００１２】
また、シート防水工法用断熱材のための架橋ポリオレフィン発泡シートの好適な製造方法として、本発明においては、ポリオレフィン樹脂に発泡剤および化学架橋剤の配合された発泡性ポリオレフィン樹脂組成物を成形した母板シートの両表面に電子線照射を行って表面近傍のみを電子線架橋させた後、加熱して全体を化学架橋させるとともに発泡させることを特徴とする製造方法が提供される。
【００１３】
本発明における架橋ポリオレフィン発泡シートの緻密な表皮層は、電子線架橋と化学架橋の両者の架橋を施すことによって得ることができる。また、その内層は化学架橋のみが施された発泡層とすることによって耐圧縮性に優れた高倍率発泡体とすることができる。このような発泡シートは、表皮層の平均厚さが２０μｍ以上で、表皮近傍の材料破壊強度が１．５ｋｇ／２５ｍｍ以上、平均高低差が２００μｍ以下の表面平滑性を有する。
【００１４】
なお、ここでいう材料破壊強度は、次のように測定する。まず、(1)厚さ２ｍｍの塩ビシートに接着剤２５０ｇ／ｍ²をくしごてを用いて塗布し、室温で５分間乾燥させる、(2)これにプライマー付き発泡シートを重ね合わせゴムローラで圧着し、２４時間以上放置する、(3)引張速度２００ｍｍ／分で１８０度方向の剥離試験を行い発泡シートが材料破壊した場合、その強度をもって材料破壊強度（＝表皮強度）という。
また、表皮層の平均厚さおよび表皮表面の平均高低差は、任意の複数箇所の発泡シート断面のＳＥＭ（走査型電子顕微鏡）写真像から測定し平均値から求める。写真の拡大倍率は特に限定するものではないが、例えば、平均厚さを求める場合には２００倍程度、高低差を求めるときには３５倍程度とする。
【００１５】
本発明における架橋ポリオレフィン発泡シートは例えば次のような方法で製造することができる。まず、ポリオレフィン樹脂１００重量部に対して、ジクミルパーオキサイド、ジターシャリーブチルパーオキサイド、2,5-ジメチル2,5ージ（ターシャリーブチルパーオキシ）ヘキサンなどの架橋剤０．５〜１．５重量部およびジアゾカーボンアミド、ＮＮ’ジニトロソペンタメチレンテトラミンなどの発泡剤１０〜２５重量部を必須成分として配合した混和物とする。次に、この混和物を架橋剤および発泡剤の分解温度以下の温度で溶融押出成形して母板シートとし、この母板シートの両面に（室温で）電子線を照射して母板シート表面のみ架橋させる。ついで、この照射済み母板シートを、例えば金網製コンベアを有する熱風加熱炉中で架橋剤および発泡剤の分解温度以上に加熱して母板全体を化学架橋させると同時に発泡させ、冷却工程を経て架橋ポリオレフィン発泡シートを製造する。
【００１６】
ここで、電子線照射は、加速電圧１５０〜３５０ｋＶ、特に２００〜３００ｋＶ，照射線量１０〜１５０ｋＧｙ、特に４０〜１００ｋＧｙの条件下で行うのが好ましい。このような条件下で電子線照射を行うと、表皮近傍の架橋とシート内部の発泡性とのバランスがとれ、シート防水工法用断熱材に適した、適度の表皮強度をもつ高発泡倍率の発泡シートが得られる。
また、本発明における架橋ポリオレフィン発泡シートは、耐圧縮性、断熱性の観点から、発泡倍率２０〜４０倍（無機物を充填していない場合、密度0.025〜0.05ｇ／ｃｃ程度）、特に２５〜３５倍の範囲のものが好適である。さらに、発泡シートの厚さは、特に制限されるものではないが、通常５〜５０ｍｍ程度のものが用いられる。発泡シートは、１枚で構成されていてもよいし、複数枚を積層したものでもよい。発泡シートの厚さが１５ｍｍ以上のものは通常積層して使用される。
【００１７】
なお、本発明におけるポリオレフィン樹脂としては、例えば、ポリエチレン；エチレン−アクリル酸アルキルエステル共重合体、エチレン−酢酸ビニル共重合体、エチレン−αオレフィン共重合体などのエチレン系共重合体の群から選ばれるいずれか１種もしくは２種以上の混合物を用いることができる。
また、前記混和物にはその他の添加剤として、酸化防止剤、着色剤、難撚剤、充填剤などを適宜配合することができる。
【００１８】
本発明のシート防水工法用断熱材は、上記のような特定構造の架橋ポリオレフィン発泡シートの両表面に接着層が設けられ、その少なくとも一方の接着剤層の上には両面離型性を有する離型フィルムが設けられている。この接着剤層は、市販の塗工設備により２５〜５０ｇ／ｍ²程度の量の接着剤を架橋ポリオレフィン発泡シート上に塗工し乾燥して設ける。接着剤としては、塩ビシート用としてニトリルゴム系接着剤が、ゴムシート用としてクロロプレン系接着剤が接着力の点で好ましい。
【００１９】
また、離型フイルムとしては、接着剤層から容易に剥離ができるとともに、本発明の断熱材を長尺の巻回体としてもしくは定尺体複数枚を重ねて保管、運搬ができるように、その両表面離型性を有するものが用いられ、ポリエチレンフィルム、ポリエステルフィルムなどのプラスチックフイルムが好適である。
また、架橋ポリオレフィン発泡シートはその両表面にコロナ処理が施されていることが望ましい。コロナ処理により表面ぬれ指数を４０dyne／ｃｍ以上とすることができ、発泡シートの両面に塗布される接着剤との親和性を向上させることができる。
【００２０】
【作用】
本発明における架橋ポリオレフィン発泡シートは、表皮表面の凹凸の山と谷の平均高低差が２００μｍ以下の平滑性を有するので、接着剤が均一に塗布され、塗布量が２５〜５０ｇ／ｍ²程度で充分な接着力（１．５ｋｇ／２５ｍｍ以上）が得られ、強風時の負圧が加わっても接着界面からの剥離を防止できる。また、平均厚さ２０μｍ以上の緻密な表皮層を有しており、表皮近傍の材料破壊強度（表皮強度）が１．５ｋｇ／２５ｍｍ以上と高いので、強風時の負圧によって防水シートに剥離力が加わっても、発泡シートが材料破壊することもない。
【００２１】
さらに、架橋ポリオレフィン発泡シートの両表面には接着剤層が工場内で設けられているので、塗布量管理により安定した接着力が得られるうえ、現場でのロール刷毛による接着剤塗工時の静電気発生がないため溶剤への引火のおそれもない。また、現場での接着剤塗工はコンクリート下地面と防水シート裏面の２面のみであるので、オープンタイムをとるための面積は半分で済み、現場での接着剤使用量が従来の半分で済む。現場での接着剤の準備も種類が少なくて済む。
また、本発明の断熱材は保管、運搬の都合上、長尺の巻回体として重ね巻きしてもしくは定尺体複数枚を重ねて製品化、流通することになるが、その際接着剤層の少なくとも一方の面に両面離型性を有する離型フィルムが貼付されているので、結果的にゴミなどの接着阻害因子から両面の接着剤層が同時に保護され、接着性能が維持できる。しかも、本発明の断熱材を屋上で施工する際には、離型フィルムを貼付した側を上にして他方の接着剤層側をコンクリートスラブ上に貼り付け、そのあと離型フィルムを剥せば、直ちに次工程の防水シート貼着工程に入ることができる。離型フィルムを矧がす前であれば、その上を歩くこともできる。
【００２２】
【実施例】
実施例１
高圧法ポリエチレン（密度0.920ｇ／ｃｍ³、ＭＩ0.8）１００重量部に対して、アゾジカーボンアミドを１７重量部、ジクミルパーオキサイド０．８重量部を配合し、均一に混合し、これを押出機により幅３５０ｍｍ、厚さ２．５ｍｍの発泡用母板シートを製造した。
次に、この発泡用母板シートの上下両面に加速電圧３００ｋＶの電子線照射器で表裏面に７０ｋＧｙ照射しこの照射シートを金網製コンベアに載せて加熱炉中で２２０℃の熱風を５分間送って加熱し発泡させた。
その結果、幅１０００ｍｍ，厚さ１０ｍｍ、密度が0.03ｇ／ｃｃで、両表面層のみに電子線照射と化学架橋が施された緻密な表皮層からなり、内層は化学架橋が施された架橋ポリエチレン発泡シートが得られた。このシートの１０箇所を切り取りそれぞれにつきその断面のＳＥＭ写真（２００倍、３５倍）を撮り、表皮部の緻密な気泡部分の厚さおよび表皮表面の高低差を測定し、平均値を求めたところ、表皮層の平均厚みは２５μｍ、表皮表面の凹凸の山と谷の平均高低差は約１００μｍであった。
【００２３】
得られた架橋ポリエチレン発泡シートの表裏にコロナ放電処理を施し、表面濡れ指数を４５ｄｙｎ／ｃｍとして、更にその表裏面にＮＢＲ系接着剤を４０ｇ／ｍ²（固形分２０重量％）塗工し、赤外線ヒーターで十分に乾燥して接着剤層を設け、その一方の接着剤層に離型用ポリエチレンフィルムを貼付してロール状に巻き取った本発明の防水シート工法用断熱材を得た。
厚さ８ｍｍのコンクリートスレート板（ＪＩＳＡ−５４０３(F)）面にＮＢＲ系接着剤をロール刷毛で２５０ｇ／ｍ²の割合で塗工し、オープンタイムを３０分とった後、上記の断熱材を離型用ポリエチレンフィルム側を上にして貼り付け、ロール転圧（線圧２ｋｇ／ｃｍ）した。さらに、塩ビシート面にＮＢＲ系接着剤を２５０ｇ／ｍ²塗工しオープンタイムを３０分とって接着剤付き塩ビシートを用意し、先に貼り付けた断熱材から離型用ポリエチレンフィルムを剥し直ちにその上に接着剤付き塩ビシートを貼り付けロール転圧した。本試験片を２０℃、６５％ＲＨの環境下で１６８時間養生したのち、引っ張り速度２００ｍｍ／分で１８０度剥離試験を行ったところ、常態接着力は１．９ｋｇ／２５ｍｍであり、発泡シートの材料破壊が起こった（強風時の負圧には充分耐える表皮強度であることは言うまでもない）。また、接着作業時に静電気の発生は全く見られなかった。
【００２４】
実施例２
実施例１で得たと同じ架橋ポリエチレン発泡シートの両表面にコロナ放電処理を施し、表面濡れ指数を４５ｄｙｎ／ｃｍとして、更にその表裏面にＣＲ系接着剤を３０ｇ／ｍ²（固形分２３重量％）塗工し、赤外線ヒーターで十分に乾燥して接着剤層を設け、その一方の接着剤層に離型用ポリエチレンフィルムを貼付して本発明の防水シート工法用断熱材を得た。
厚さ８ｍｍのコンクリートスレート板（ＪＩＳＡ−５４０３(F)）にＣＲ系プライマーを１５０ｇ／ｍ²塗工し、オープンタイムを１５分とった後、この上にＣＲ系接着剤を２００ｇ／ｍ²塗工し、オープンタイムを３０分とった。この上に上記の断熱材を離型用ポリエチレンフィルム側を上にして貼り付け、ロール転圧（線圧２ｋｇ／ｃｍ）した。さらに、ゴム（ＥＰＤＭ）シート面にＣＲ系接着剤を２００ｇ／ｍ²塗工しオープンタイムを３０分とって接着剤付きゴムシートを用意し、先に貼り付けた断熱材から離型用ポリエチレンフィルムを剥し直ちにその上に接着剤付きゴムシートを貼り付けロール転圧した。本試験片を実施例１と同様に養生したのち、実施例１と同様の条件で剥離試験を行ったところ、常態接着力は１．９ｋｇ／２５ｍｍであり、発泡シートの材料破壊が起こった（強風時の負圧には充分耐える表皮強度であることは言うまでもない）。
【００２５】
比較例１
実施例１と同じ出発原料を用いて、押出機により実施例１と同サイズの発泡用母板シートを製造した。
次に、電子線照射を行わずに母板シートを金網製コンベアに載せて加熱炉中で２２０℃の熱風を５分間送って加熱し発泡させた。
その結果、幅１０００ｍｍ，厚さ１０ｍｍ、密度が0.03ｇ／ｃｃの化学架橋が施された架橋ポリエチレン発泡シートが得られた。このシートの１０箇所を切り取りそれぞれにつきその断面のＳＥＭ写真（２００倍、３５倍）を撮り、表皮部の緻密な気泡部分の厚さおよび表皮表面の高低差を測定し、平均値を求めたところ、表皮層の平均厚みは２５μｍ、表皮表面の凹凸の山と谷の平均高低差は約３００μｍであった。
【００２６】
得られた架橋ポリエチレン発泡シートの表裏にコロナ放電処理を施し、表面濡れ指数を４５ｄｙｎ／ｃｍとして、更にその表裏面にＮＢＲ系接着剤を４０ｇ／ｍ²（固形分２０％）塗工し、赤外線ヒーターで十分に乾燥して接着剤層を設け、その一方の接着剤層に離型用ポリエチレンフィルムを貼付して断熱材を得た。
以下実施例１と同様にして試験片を作り同条件で剥離試験をおこなったところ、常態接着力は０．５ｋｇ／２５ｍｍで、発泡シート表面からの剥離であった。
【００２７】
比較例２
高圧法ポリエチレン（密度0.921ｇ／ｃｍ³、ＭＩ６）１００重量部に対して、アゾジカーボンアミドを１７重量部、ステアリン酸亜鉛、酸化亜鉛各０．５重量部を配合し、均一に混合し、これを押出機により幅３５０ｍｍ、厚さ1.3ｍｍの発泡用母板シートを製造した。
次に、この発泡用母板シートの上下両面に加速電圧５００ｋｖの電子線照射器で表裏面に７０ｋＧｙ照射しこの照射シートを金網製コンベアに載せて加熱炉中で２２０℃の熱風を５分間送って加熱し発泡させた。
その結果、幅１０００ｍｍ，厚さ５ｍｍ、密度が0.03ｇ／ｃｃの電子線架橋ポリエチレン発泡シートが得られた。このシートの１０箇所を切り取りそれぞれにつきその断面のＳＥＭ写真（２００倍、３５倍）を撮り、表皮部の緻密な気泡部分の厚さおよび表皮表面の高低差を測定し、平均値を求めたところ、表皮層の平均厚みは１５μｍ、表皮表面の凹凸の山と谷の平均高低差は約１００μｍであった。
【００２８】
得られた架橋ポリエチレン発泡シートの表裏にコロナ放電処理を施し、表面濡れ指数を４５ｄｙｎ／ｃｍとしたのち、２枚重ねて貼り合わせて厚さ１０ｍｍの発泡シートとした。更にその表裏面にＮＢＲ系接着剤を４０ｇ／ｍ²（固形分２０％）塗工し、赤外線ヒーターで十分に乾燥して接着剤層を設け、その一方の接着剤層に離型用ポリエチレンフィルムを貼付して断熱材を得た。
以下実施例１と同様にして試験片を作り同条件で剥離試験をおこなったところ、常態接着力は０．７ｋｇ／２５ｍｍで、発泡シート表皮の材料破壊であった。
【００２９】
【発明の効果】
以上の実施例、比較例からわかるように、本発明の防水シート工法用断熱材によれば、施工現場で断熱材の表裏面に接着剤を塗工することなく、強風時の負圧にも耐える接着力（材料破壊強度）が得られ、接着剤の総使用量を少なくするとともに、現場での接着剤塗工作業を少なくすることができ、特に断熱材表面へのロール刷毛塗工作業がなくなるので静電気発生による引火の危険を回避できる。さらに、本発明によれば、現場での接着剤塗工面積が半減し、断熱材貼付の作業性が著しく改善される結果、工期の大幅短縮が可能となる。
また、本発明の製造方法によれば、緻密な表皮層を有し、表皮近傍の材料破壊強度が大きく、耐圧縮性、断熱性に優れた、防水シート工法用断熱材に適した発泡シートを提供することができる。[0001]
[Industrial application fields]
The present invention relates to a heat insulating material used in a sheet waterproofing method applied to roof concrete of buildings such as buildings for the purpose of heat insulation and waterproofing, and a method for producing a crosslinked polyolefin foam sheet used therefor.
[0002]
[Prior art]
The waterproof sheet construction method is, for example, a waterproof sheet made of a heat insulating material such as a resin foam sheet, vinyl chloride resin (hereinafter abbreviated as polyvinyl chloride), ethylene propylene diene rubber (EPDM), etc., on the roof of a concrete building with an adhesive. It is a construction method that waterproofs and insulates buildings by sticking them sequentially.
[0003]
A concrete example of the conventional sheet waterproofing method in the case of a PVC waterproof sheet is 250 g / g of rubber adhesive such as styrene butadiene rubber (SBR) or nitrile rubber (NBR) on the concrete base of the building roof. A step of applying and drying about m ² , and then a chloroprene rubber (CR) system using a roll brush or the like on one side of a polyethylene foam sheet having a thickness of about 10 to 50 mm and an expansion ratio of about 20 to 30 times. an adhesive is applied about 250 g / m ^2, after taking a sufficient open time, step of attaching the adhesive coated surface, then further by using a roll brush on the foam sheet coated with the CR based adhesive After taking sufficient open time, apply NBR adhesive to a PVC sheet with a thickness of about 2 mm in the same way, and paste it with sufficient open time. It consists of a process of attaching.
[0004]
Here, in this waterproof sheet construction method, a negative pressure is generated on the rooftop in a strong wind, and this negative pressure acts as a peeling force to the sheet. Therefore, at least the adhesive force between the sheets is 1 kg / 25 mm or more, preferably 1 It is required to be 5 kg / 25 mm or more.
[0005]
[Problems to be solved by the invention]
As described above, in the conventional sheet waterproofing construction method, the number of times of application of the adhesive is large, a plurality of types of adhesives are used, and the work is on-site work. Therefore, the work is extremely complicated. In addition, the work of applying the adhesive on site is likely to ignite because the adhesive contains solvent such as toluene, acetone, etc. Due to the nature of the resin foam sheet, roll brush etc. When this was used, static electricity was generated, and there was an accident in which the solvent was ignited by this discharge, and there was a demand for a construction method that did not generate static electricity.
[0006]
Furthermore, it is necessary to apply the adhesive on the concrete surface of the base, the front and back surfaces of the resin foam sheet as the heat insulating material, and the waterproof sheet surface in total, and the adhesive can be used in a limited space on the roof. It was necessary to spread the sheet coated with adhesive during the open time for drying the surface coated with. During this time, it was impossible to work if it rained or a strong wind was blowing, so it was necessary to work while predicting the weather conditions, and there was a big problem in managing the progress of the construction period.
[0007]
For this reason, recently, a resin foam sheet with adhesive is prepared by applying a CR adhesive to the surface of the resin foam sheet at the factory in advance, and brought to the construction site. There is an urgent need to establish a method for bonding to the surface.
[0008]
By the way, there are two production methods of the cross-linked polyolefin foam sheet, which is preferably used because of its good solvent resistance as a heat insulating material for the sheet waterproofing method, and there are disadvantages in each of the chemical cross-linking method and the electron beam cross-linking method. Was.
That is, the cross-linked polyolefin foam sheet by the chemical cross-linking method is a base sheet obtained by melt extrusion molding a composition in which a cross-linking agent and a thermal decomposition type foaming agent are blended with polyolefin at a temperature lower than the decomposition temperature of the cross-linking agent and the foaming agent. Obtained by crosslinking and foaming in a heating furnace. The surface of the foam sheet has a surface film thickness of 20 to 30 μm, and if the cohesive force of the adhesive is sufficiently large, it exhibits an adhesive force of 1.5 kg / 25 mm or more. The amount of adhesive applied was at least 100 g / m ² , preferably 200 g / m ² or more. However, in a general adhesive coating facility, only about 50 g / m ² can be applied at most. Therefore, when using a chemically crosslinked polyolefin foam sheet as a heat insulating material, thick coating of the adhesive is performed on site. However, it was necessary to carry out the coating work with a roll brush or the like.
[0009]
On the other hand, a cross-linked polyolefin foam sheet by electron beam cross-linking method is a cross-section of a base plate sheet obtained by melt-extrusion of a composition in which a polyolefin is blended with a heat decomposable foaming agent at a temperature below the decomposition temperature of the foaming agent. Then, it is obtained by foaming in a heating furnace. Since the surface of this foam sheet is as thin as 8 to 12 μm and the surface is smooth, if the applied amount of the adhesive applied in advance is 25 g / m ² or more, the adhesive strength sufficient to destroy the material is obtained. Although the material break strength (skin strength) is low due to the fact that the degree of cross-linking of the foam layer under the epidermis is not sufficiently high and the thickness of the skin film is thin, it is about 0.7 to 1 kg / 25 mm Since only adhesive strength (material destruction) can be obtained and it cannot withstand negative pressure during strong winds, it has been difficult to use as a heat insulating material for sheet waterproofing.
[0010]
Therefore, the present invention solves the above-described various problems in the sheet waterproofing method, minimizes the adhesive coating work on site, reduces the total amount of adhesive used, and improves the workability of applying a heat insulating material. It is an object of the present invention to provide a heat insulating material for a sheet waterproofing method that can withstand the negative pressure in a strong wind and a method for producing a crosslinked polyolefin foam sheet used therefor.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, an adhesive layer is provided on both surfaces of a crosslinked polyolefin foam sheet, and a release film having a double-sided release property is affixed on at least one of the adhesive layers. In the heat-insulating material for waterproof sheet construction , the cross-linked polyolefin foam sheet is irradiated with an electron beam under conditions of an acceleration voltage of 150 to 300 kV and an irradiation dose of 10 to 150 kGy on both surfaces of a base sheet containing a chemical crosslinking agent before crosslinking and foaming. After the electron beam cross-linking only in the vicinity of the surface by heating, the whole is chemically cross-linked and foamed, and the cross-linked polyolefin foam sheet has a dense skin layer with an average thickness of 20 μm or more on both sides. And the material fracture strength in the vicinity of the skin is 1.5 kg / 25 mm or more, and the average height difference between the ridges and valleys on the surface of the skin is 2 Sheet waterproofing method for heat insulating material, characterized in that it comprises the following smoothness 0μm is provided.
[0012]
In addition, as a preferred method for producing a crosslinked polyolefin foam sheet for a heat insulating material for sheet waterproofing, in the present invention, a mother material obtained by molding a foamable polyolefin resin composition in which a foaming agent and a chemical crosslinking agent are blended with a polyolefin resin. There is provided a manufacturing method characterized in that both surfaces of a plate sheet are irradiated with an electron beam to crosslink only the vicinity of the surface with an electron beam, and then heated to chemically crosslink and foam the whole.
[0013]
The dense skin layer of the crosslinked polyolefin foam sheet in the present invention can be obtained by performing both electron beam crosslinking and chemical crosslinking. Moreover, the inner layer can be made into the high magnification foam excellent in compression resistance by making it the foaming layer to which only the chemical crosslinking was given. Such a foam sheet has a surface smoothness with an average thickness of the skin layer of 20 μm or more, a material breaking strength in the vicinity of the skin of 1.5 kg / 25 mm or more, and an average height difference of 200 μm or less.
[0014]
Here, the material breaking strength is measured as follows. First, (1) a thickness of 2mm of the PVC sheet to the adhesive 250 g / m ² was applied using a comb iron, dried 5 minutes at room temperature, pressed under a rubber roller superposed primer with foamed sheet to (2) (3) When a foam sheet is subjected to a 180 ° peel test at a tensile speed of 200 mm / min and the foamed sheet breaks down, the strength is referred to as the material breaking strength (= skin strength).
Further, the average thickness of the skin layer and the average height difference of the skin surface are determined from the average values measured from SEM (scanning electron microscope) photographic images of the foam sheet cross-sections at arbitrary multiple locations. The magnification of the photograph is not particularly limited. For example, it is about 200 times when the average thickness is obtained, and about 35 times when the height difference is obtained.
[0015]
The crosslinked polyolefin foam sheet in the present invention can be produced, for example, by the following method. First, with respect to 100 parts by weight of polyolefin resin, a crosslinking agent such as dicumyl peroxide, ditertiary butyl peroxide, 2,5-dimethyl 2,5-di (tertiary butyl peroxy) hexane, 0.5-1. An admixture containing 5 parts by weight and 10 to 25 parts by weight of a foaming agent such as diazocarbonamide and NN′dinitrosopentamethylenetetramine as essential components is used. Next, this mixture is melt-extruded at a temperature lower than the decomposition temperature of the crosslinking agent and the foaming agent to form a mother sheet, and both surfaces of the mother sheet are irradiated with electron beams (at room temperature) to obtain the mother sheet surface. Only crosslink. Next, the irradiated mother sheet is heated to a temperature higher than the decomposition temperature of the crosslinking agent and the foaming agent in a hot-air heating furnace having a wire mesh conveyor, for example, and the entire mother board is chemically crosslinked and foamed, and then subjected to a cooling step. A crosslinked polyolefin foam sheet is produced.
[0016]
Here, the electron beam irradiation is preferably performed under the conditions of an acceleration voltage of 150 to 350 kV, particularly 200 to 300 kV, and an irradiation dose of 10 to 150 kGy, particularly 40 to 100 kGy. When the electron beam irradiation is performed under such conditions, the foaming in the vicinity of the skin and the foamability inside the sheet are balanced, and foaming with a high foaming ratio having an appropriate skin strength suitable for the heat insulating material for the sheet waterproofing method. A sheet is obtained.
Moreover, the crosslinked polyolefin foamed sheet in the present invention has a foaming ratio of 20 to 40 times (density is about 0.025 to 0.05 g / cc when not filled with an inorganic substance), particularly 25 to 35, from the viewpoints of compression resistance and heat insulation. Those in the double range are preferred. Furthermore, the thickness of the foam sheet is not particularly limited, but a thickness of about 5 to 50 mm is usually used. The foam sheet may be composed of a single sheet or may be a laminate of a plurality of sheets. A foam sheet having a thickness of 15 mm or more is usually laminated.
[0017]
The polyolefin resin in the present invention is selected from the group of ethylene copolymers such as polyethylene; ethylene-acrylic acid alkyl ester copolymer, ethylene-vinyl acetate copolymer, ethylene-α olefin copolymer. Any one kind or a mixture of two or more kinds can be used.
Moreover, antioxidant, a coloring agent, a difficult twist agent, a filler, etc. can be suitably mix | blended with the said mixture as other additives.
[0018]
In the heat insulating material for waterproof sheet construction method of the present invention, adhesive layers are provided on both surfaces of a crosslinked polyolefin foam sheet having a specific structure as described above, and the release layer having a double-sided release property on at least one of the adhesive layers. A mold film is provided. This adhesive layer is provided by applying an adhesive in an amount of about 25 to 50 g / m ² on a cross-linked polyolefin foamed sheet using a commercially available coating facility and drying it. As the adhesive, a nitrile rubber adhesive for a vinyl chloride sheet and a chloroprene adhesive for a rubber sheet are preferable in terms of adhesive strength.
[0019]
In addition, the release film can be easily peeled off from the adhesive layer, and the heat insulating material of the present invention can be stored and transported as a long wound body or by stacking a plurality of constant length bodies. Those having both surface releasability are used, and plastic films such as polyethylene film and polyester film are suitable.
Moreover, as for the crosslinked polyolefin foam sheet, it is desirable that the corona treatment is given to the both surfaces. The surface wetness index can be made 40 dyne / cm or more by corona treatment, and the affinity with the adhesive applied to both sides of the foamed sheet can be improved.
[0020]
[Action]
The crosslinked polyolefin foamed sheet in the present invention has a smoothness with an average height difference of unevenness and valleys of the surface of the skin of 200 μm or less, so that the adhesive is uniformly applied and the coating amount is about 25 to 50 g / m ² . Sufficient adhesive force (1.5 kg / 25 mm or more) can be obtained, and peeling from the adhesive interface can be prevented even if a negative pressure is applied during strong winds. In addition, it has a dense skin layer with an average thickness of 20 μm or more, and the material breaking strength (skin strength) in the vicinity of the skin is as high as 1.5 kg / 25 mm or more. Even if added, the foamed sheet does not break the material.
[0021]
Furthermore, since both sides of the cross-linked polyolefin foam sheet are provided with an adhesive layer in the factory, a stable adhesive force can be obtained by controlling the amount of coating, and static electricity during the application of adhesive by a roll brush in the field can be obtained. There is no risk of igniting the solvent because it does not occur. Also, since there are only two adhesive coatings in the field, the concrete base surface and the waterproof sheet back surface, the area for taking the open time can be halved, and the amount of adhesive used in the field can be halved. . There are few types of adhesive preparation on site.
In addition, for the convenience of storage and transportation, the heat insulating material of the present invention will be rolled up as a long wound body, or a plurality of fixed-size bodies will be commercialized and distributed, and in that case, the adhesive layer Since a release film having double-sided releasability is affixed to at least one of the surfaces, as a result, the adhesive layers on both sides are simultaneously protected from adhesion-inhibiting factors such as dust, and adhesion performance can be maintained. Moreover, when constructing the heat insulating material of the present invention on the roof, if the release film is attached on the other adhesive layer side on the concrete slab, the release film is then peeled off. The waterproof sheet sticking process of the next process can be immediately started. You can also walk on the release film before it is scratched.
[0022]
【Example】
Example 1
17 parts by weight of azodicarbonamide and 0.8 parts by weight of dicumyl peroxide are blended with 100 parts by weight of high pressure polyethylene (density 0.920 g / cm ³ , MI 0.8) and mixed uniformly. A foaming mother sheet having a width of 350 mm and a thickness of 2.5 mm was produced using an extruder.
Next, both the upper and lower surfaces of the foam base sheet are irradiated with 70 kGy on the front and back surfaces with an electron beam irradiator with an acceleration voltage of 300 kV, and the irradiated sheet is placed on a wire mesh conveyor and heated at 220 ° C. with hot air for 5 minutes. And heated to foam.
As a result, the cross-linked polyethylene has a width of 1000 mm, a thickness of 10 mm, a density of 0.03 g / cc, and consists of a dense skin layer in which only both surface layers are subjected to electron beam irradiation and chemical crosslinking, and the inner layer is chemically crosslinked. A foam sheet was obtained. 10 portions of this sheet were cut out, SEM photographs (200 times, 35 times) of the cross section were taken for each, and the thickness of the dense bubble part of the skin part and the height difference of the skin surface were measured, and the average value was obtained. The average thickness of the skin layer was 25 μm, and the average height difference between the ridges and valleys on the surface of the skin was about 100 μm.
[0023]
Corona discharge treatment is applied to the front and back of the obtained crosslinked polyethylene foam sheet, the surface wetting index is set to 45 dyn / cm, and NBR adhesive is applied to the front and back surfaces of 40 g / m ² (solid content 20% by weight), It was sufficiently dried with an infrared heater to provide an adhesive layer, a polyethylene film for release was attached to one of the adhesive layers, and the heat insulating material for the waterproof sheet construction method of the present invention was wound up in a roll shape.
After applying NBR adhesive at a rate of 250 g / m ² with a roll brush on the surface of a concrete slate plate (JISA-5403 (F)) with a thickness of 8 mm and taking an open time of 30 minutes, The release film was attached with the polyethylene film side facing up, and roll rolling (linear pressure 2 kg / cm) was performed. Furthermore, NBR adhesive is applied to the surface of the PVC sheet at 250 g / m ² and an open time is taken for 30 minutes to prepare a PVC sheet with an adhesive. A PVC sheet with an adhesive was stuck on it and rolled. The test piece was cured for 168 hours in an environment of 20 ° C. and 65% RH, and then subjected to a 180 ° peel test at a pulling rate of 200 mm / min. The normal adhesive strength was 1.9 kg / 25 mm. Material destruction occurred (it goes without saying that the skin strength is strong enough to withstand negative pressure in strong winds). In addition, no static electricity was observed during the bonding operation.
[0024]
Example 2
Both surfaces of the same cross-linked polyethylene foam sheet obtained in Example 1 were subjected to corona discharge treatment, the surface wetting index was set to 45 dyn / cm, and a CR adhesive was applied to the front and back surfaces of 30 g / m ² (solid content 23 wt% The film was coated and sufficiently dried with an infrared heater to provide an adhesive layer, and a polyethylene film for release was attached to one of the adhesive layers to obtain a heat insulating material for waterproof sheet construction of the present invention.
Concrete slate plate with a thickness of 8mm and CR-based primer 150 g / m ² was applied to (JISA-5403 (F)) , after taking the open time 15 min, 200 g / m ² coating the CR based adhesive thereon And took an open time of 30 minutes. On top of this, the heat insulating material was affixed with the release polyethylene film side up, and roll-rolled (linear pressure 2 kg / cm). Furthermore, the rubber (EPDM) sheet surface is coated with 200 g / m ² of CR adhesive and the open time is 30 minutes to prepare a rubber sheet with an adhesive. Immediately after peeling off, a rubber sheet with an adhesive was stuck on it and rolled and rolled. After this test piece was cured in the same manner as in Example 1, a peel test was performed under the same conditions as in Example 1. As a result, the normal adhesive strength was 1.9 kg / 25 mm, and material destruction of the foamed sheet occurred ( Needless to say, it is strong enough to withstand the negative pressure during strong winds).
[0025]
Comparative Example 1
Using the same starting materials as in Example 1, a foam base sheet having the same size as in Example 1 was produced by an extruder.
Next, without performing electron beam irradiation, the base sheet was placed on a wire mesh conveyor, and heated at 220 ° C. for 5 minutes in a heating furnace to be heated and foamed.
As a result, a cross-linked polyethylene foam sheet having a chemical cross-link having a width of 1000 mm, a thickness of 10 mm, and a density of 0.03 g / cc was obtained. 10 portions of this sheet were cut out, and SEM photographs (200 times and 35 times) of the cross section were taken for each, and the thickness of the dense bubble part of the skin part and the height difference of the skin surface were measured, and the average value was obtained. The average thickness of the skin layer was 25 μm, and the average height difference between the ridges and valleys on the surface of the skin was about 300 μm.
[0026]
The cross-linked polyethylene foamed sheet is subjected to corona discharge treatment on the front and back surfaces, the surface wetting index is set to 45 dyn / cm, and the front and back surfaces are coated with 40 g / m ² (solid content 20%) of NBR adhesive. It was sufficiently dried with a heater to provide an adhesive layer, and a polyethylene film for release was attached to one of the adhesive layers to obtain a heat insulating material.
Thereafter, a test piece was prepared in the same manner as in Example 1 and a peel test was conducted under the same conditions. As a result, the normal adhesive strength was 0.5 kg / 25 mm, and the peel was from the surface of the foam sheet.
[0027]
Comparative Example 2
17 parts by weight of azodicarbonamide, 0.5 parts by weight of zinc stearate and zinc oxide are blended with 100 parts by weight of high-pressure polyethylene (density 0.921 g / cm ³ , MI6) and mixed uniformly. A foaming mother sheet with a width of 350 mm and a thickness of 1.3 mm was produced from this using an extruder.
Next, both the upper and lower surfaces of this foam base sheet are irradiated with 70 kGy on the front and back surfaces with an electron beam irradiator with an acceleration voltage of 500 kv, and this irradiated sheet is placed on a wire mesh conveyor and heated at 220 ° C. for 5 minutes in a heating furnace. And heated to foam.
As a result, an electron beam cross-linked polyethylene foam sheet having a width of 1000 mm, a thickness of 5 mm, and a density of 0.03 g / cc was obtained. 10 portions of this sheet were cut out, and SEM photographs (200 times and 35 times) of the cross section were taken for each, and the thickness of the dense bubble part of the skin part and the height difference of the skin surface were measured, and the average value was obtained. The average thickness of the skin layer was 15 μm, and the average height difference between the ridges and valleys on the surface of the skin was about 100 μm.
[0028]
The cross-linked polyethylene foamed sheet was subjected to corona discharge treatment on the front and back surfaces so that the surface wetting index was 45 dyn / cm, and then two sheets were laminated together to form a foamed sheet having a thickness of 10 mm. Furthermore, 40 g / m ² (solid content 20%) of NBR-based adhesive was applied to the front and back surfaces, and dried sufficiently with an infrared heater to provide an adhesive layer. One of the adhesive layers was a polyethylene film for mold release. Was attached to obtain a heat insulating material.
Thereafter, a test piece was prepared in the same manner as in Example 1 and a peel test was performed under the same conditions. As a result, the normal adhesive strength was 0.7 kg / 25 mm, which was a material destruction of the foam sheet skin.
[0029]
【The invention's effect】
As can be seen from the above Examples and Comparative Examples, according to the heat insulating material for waterproof sheet construction method of the present invention, without applying an adhesive on the front and back surfaces of the heat insulating material at the construction site, even in negative pressure during strong winds Adhesive strength (material breaking strength) can be obtained, the total amount of adhesive used can be reduced, and on-site adhesive coating work can be reduced, especially roll brush coating work on the surface of insulation materials. Because it disappears, the danger of ignition due to static electricity can be avoided. Furthermore, according to the present invention, the adhesive application area in the field is halved and the workability of applying the heat insulating material is remarkably improved, so that the construction period can be greatly shortened.
In addition, according to the production method of the present invention, a foam sheet having a dense skin layer, having a large material fracture strength near the skin, excellent in compression resistance and heat insulation, and suitable for a heat insulating material for a waterproof sheet construction method. Can be provided.

Claims

Adhesive layer is provided on both sides of the crosslinked polyolefin foam sheet, at least one of its adhesive layer in the sheet waterproofing construction method insulation material release film having a double-sided releasing property is attached, the crosslinked polyolefin foam After the sheet is irradiated with an electron beam under conditions of an acceleration voltage of 150 to 300 kV and an irradiation dose of 10 to 150 kGy on both surfaces of the base sheet containing the chemical crosslinking agent before crosslinking and foaming, only the vicinity of the surface is electron beam crosslinked The crosslinked polyolefin foamed sheet is heated and chemically crosslinked and foamed. The crosslinked polyolefin foam sheet has a dense skin layer with an average thickness of 20 μm or more on both sides, and a material fracture strength in the vicinity of the skin is 1. It is 5 kg / 25 mm or more, and it has a smoothness with an average height difference between uneven peaks and valleys on the surface of the skin of 200 μm or less. Thermal insulation material for waterproofing method.