JP2004269679A - Adhesive, its manufacturing method and plastic film-laminated sheet iron - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive having an excellent heat resistance after used in a laminate and a high adhesion strength after subjected to a boiling water resistance test, its manufacturing method and a plastic film-laminated sheet iron. <P>SOLUTION: The adhesive contains (A) a blocked isocyanate group-containing polyester polyurethane which is obtained by blocking the unreacted isocyanate group of (A') an isocyanate group-containing polyester polyurethane obtained by reacting (P) a hydroxyl group-containing compound component containing (p1) a polyester polyol and (p2) a hydroxyl group-containing silicone compound with (Q) a polyisocyanate compound under the condition that the amount of the isocyanate groups exceeds the total amount of the hydroxyl groups of the component (P), (B) an epoxy resin and (C) an acid-modified polyolefin resin. The manufacturing method of the adhesive comprises mixing the polyurethane (A), the epoxy resin (B) and the acid-modified polyolefin resin (C). The plastic film-laminated sheet iron is manufactured using the adhesive. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

（式中、Ｒ^１は、エポキシ樹脂残基である）
で表される化合物、又は、一般式（２）：
【化２】

（式中、Ｒ^２及びＲ^３は、エポキシ樹脂残基である）
で表される化合物である。
【００３５】
特に好ましいエポキシリン酸エステル樹脂（ｂ１）は、分子末端にリン酸基と一級水酸基を有する化合物であり、特に好ましいエポキシリン酸エステル樹脂（ｂ１）は、一般式（３）：
【化３】

（式中、Ｒ^４は、エポキシ樹脂残基である）
で表される化合物である。
【００３６】
エポキシリン酸エステル樹脂（ｂ１）としては、市販品を用いることもでき、具体的には、ＤＥＲ６２１−ＥＢ５０〔ダウ・ケミカル日本（株）社製；固形分５０％〕が好ましい。更に、前記のＤＥＲ６２１−ＥＢ５０と同等の特性値を有するものも好適に使用することができる。
【００３７】
前記のエポキシ樹脂（Ｂ）として、エポキシリン酸エステル樹脂（ｂ１）を用いる場合には、本発明の接着剤は、前記エポキシリン酸エステル樹脂（ｂ１）を、前記ブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）の固形分１００重量部に対して、好ましくは０．５〜３．５重量部、より好ましくは１．５〜２．５重量部の量で含有することができる。前記のエポキシリン酸エステル樹脂（ｂ１）の含有量が３．５重量部を越えると、（Ａ）成分との相溶性が悪くなり鋼板及びプラスチックフィルムとの接着性が不良となることがあり、０．５重量部未満になると鋼板との接着性や耐湿性が不良となることがある。
【００３８】
前記のエポキシ樹脂（Ｂ）としては、前記のエポキシリン酸エステル樹脂（ｂ１）の代わりに、あるいは前記のエポキシリン酸エステル樹脂（ｂ１）に加えて更に、非リン酸変性エポキシ樹脂（ｂ２）を含有することができ、後者、すなわち（ｂ１）及び（ｂ２）を同時に含有することが好ましい。ここで、非リン酸変性エポキシ樹脂（ｂ２）とは、前記のエポキシリン酸エステル樹脂（ｂ１）とは異なるエポキシ樹脂を意味し、リン酸による変性をされていない任意のエポキシ樹脂を意味する。従って、この非リン酸変性エポキシ樹脂（ｂ２）は、水酸基を含有しないエポキシ樹脂（ｂ２−１）又は水酸基を含有するエポキシ樹脂（ｂ２−２）であることができ、耐熱性（接着性）の点で好ましいので、水酸基不含有エポキシ樹脂（ｂ２−１）を好適に使用することができる。
【００３９】
更に、前記の非リン酸変性エポキシ樹脂（ｂ２）として、水酸基不含有エポキシ樹脂（ｂ２−１）を使用すると、本発明の接着剤に耐熱性や鋼板との接着性を付与することができる。このような水酸基不含有エポキシ樹脂（ｂ２−１）としては、例えば、フェノールノボラック型エポキシ樹脂及び／又はクレゾールノボラック型エポキシ樹脂を用いることができ、クレゾールノボラック型エポキシ樹脂を用いるのが好ましい。フェノールノボラック型エポキシ樹脂又はクレゾールノボラック型エポキシ樹脂の数平均分子量は特に限定されないが、好ましくは３００〜８００より好ましくは４００〜６００である。クレゾールノボラック型エポキシ樹脂としては、市販品を用いることもでき、例えば、アラルダイトＥＣＮ１２７３〔旭化成エポキシ（株）社製〕を用いるのが好ましい。
【００４０】
本発明の接着剤は、前記の水酸基不含有エポキシ樹脂（ｂ２−１）を、前記ブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）の固形分１００重量部に対して、好ましくは２〜６重量部、より好ましくは４〜５重量部の量で含有することができる。前記の水酸基不含有エポキシ樹脂（ｂ２−１）の含有量が６重量部を越えると、加工性不良となることがあり、２重量部未満になると耐熱性及び鋼板との接着不良となることがある。また、４〜５重量部の量で含有すると、優れた耐熱性と接着性を得ることができる。
【００４１】
一方、固形のエポキシ樹脂〔例えば、エピコート１００１〕を前記の水酸基含有エポキシ樹脂（ｂ２−２）として使用すると、ブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）と単に混合するだけであるので、水酸基含有エポキシ樹脂（ｂ２−２）の水酸基がブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）のイソシアネート基と反応することはない。しかしながら、接着剤が塗工後に加熱されると、ブロック化イソシアネート基が脱ブロック化して遊離イソシアネート基が再現するため、この遊離イソシアネート基と固形エポキシ樹脂に含まれる水酸基とが結合して接着剤としての機能を果たすことができる。
【００４２】
本発明の接着剤は、前記の水酸基含有エポキシ樹脂（ｂ２−２）を、前記ブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）の固形分１００重量部に対して、好ましくは１〜７重量部、より好ましくは３〜５重量部の量で含有することができる。前記の水酸基含有エポキシ樹脂（ｂ２−２）の含有量が７重量部を越えると、加工性不良となることがあり、１重量部未満になると鋼板との接着性不良となることがある。
【００４３】
本発明の接着剤は、更に、酸変性ポリオレフィン樹脂（Ｃ）を含有する。酸変性ポリオレフィン樹脂（Ｃ）を使用することにより、特にポリオレフィンとの接着性を向上させることができる。
酸変性ポリオレフィン樹脂は、例えば、ポリオレフィン樹脂に、エチレン性不飽和基を含む酸無水物をグラフト重合させることによって調製することができる。ポリオレフィン樹脂としては、例えば、ポリエチレン、ポリプロピレン、エチレン−プロピレン共重合体、又はエチレン−酢酸ビニル共重合体等を挙げることができる。また、エチレン性不飽和基を含む酸無水物としては、例えば、無水マレイン酸、無水フマル酸、マレイン酸、フマル酸、又はイタコン酸等を挙げることができ、無水マレイン酸を好適に使用することができる。
更に、酸変性ポリオレフィン樹脂としては、オレフィンとエチレン性不飽和基含有カルボン酸との共重合体（例えば、エチレン−アクリル酸共重合体、又はエチレン−メタクリル酸共重合体）の単量体又は混合体を用いることもできる。
【００４４】
本発明の接着剤において、前記の酸変性ポリオレフィン樹脂（Ｃ）の含有量は、前記ブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）の固形分量比（Ａ／Ｃ）として、好ましくは５０／５０〜９０／１０、より好ましくは７５／２５〜８０／２０である。前記の酸変性ポリオレフィン樹脂（Ｃ）の含有量が前記固形分量比（Ａ／Ｃ）の５０／５０より多くなると、鋼板との接着性不良や粘度上昇による塗工性不良となることがあり、９０／１０より少なくなると、プラスチックフィルムとの接着不良となることがある。また、前記の酸変性ポリオレフィン樹脂（Ｃ）の含有量が前記固形分量比（Ａ／Ｃ）の７５／２５〜８０／２０の範囲内にあると、好適な接着剤粘度が得られ、優れた塗工性が得られる。
【００４５】
本発明の接着剤は、前記のブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）と、前記のエポキシ樹脂（Ｂ）と、前記の酸変性ポリオレフィン樹脂（Ｃ）とを単に混合することによって調製することができる。前記の混合は、有機溶媒、例えば、脂肪族ケトン（例えば、メチルエチルケトン）又は脂環式ケトン（例えば、シクロヘキサノン）の中で行うことができ、脂肪族エステル（例えば、酢酸エチルや酢酸ブチル）を併用することもできる。
【００４６】
前記の混合の順序も限定されない。例えば、前記のブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）と前記のエポキシ樹脂（Ｂ）とを混合してから、前記の酸変性ポリオレフィン樹脂（Ｃ）を添加することもできるし、前記のエポキシ樹脂（Ｂ）と前記の酸変性ポリオレフィン樹脂（Ｃ）とを混合してから、前記のブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）を添加することもできるし、前記のブロック化イソシアネート基含有ポリエステルポリウレタン（Ａ）と前記の酸変性ポリオレフィン樹脂（Ｃ）とを混合してから、前記のエポキシ樹脂（Ｂ）を添加することもできる。
【００４７】
本発明の接着剤を用いて、鋼板にプラスチックフィルムをラミネートすることができる。プラスチックフィルムは、特に限定されないが、本発明の接着剤を用いると、難接着性材料であるポリオレフィンフィルムを鋼板にラミネートすることができる。ポリオレフィンフィルムとしては、例えば、ポリエチレン又はポリプロピレンを挙げることができる。ラミネートすることのできるポリオレフィンフィルムの厚みは、特に限定されないが、例えば、５００μｍ前後の厚さのものも使用することができる。
【００４８】
鋼板は、特に限定されないが、例えば、ステンレス鋼基材、又は亜鉛めっき鋼基材等の一般的な鋼板基材を使用することができる。前記の亜鉛めっき鋼基材の表面上の亜鉛めっきは、例えば、鋼板を母材として、これに純亜鉛めっき、又は亜鉛合金めっきのいずれかの処理を施したものでよく、更にこれに他のめっきを複層状に施したものでもよい。
【００４９】
これらの鋼板基材には、必要な場合、下地処理を施すことができる。ステンレス鋼板では、下地処理を特に必要としないが、クロメート処理により、ポリオレフィンフィルムとの密着性を更に向上させることができる。亜鉛めっき鋼板では、リン酸塩処理又はクロメート処理のいずれか一方、あるいは両方の処理を施す必要がある場合もある。これらのクロメート処理及び／又はリン酸処理により、ポリオレフィンフィルムラミネート鋼板において、ポリオレフィンフィルムの密着性を向上させることができる。リン酸塩処理及びクロメート処理については、特に制限なく、従来の一般的な方法によることができる。
【００５０】
本発明のポリオレフィンフィルムラミネート鋼板を製造する場合は、前記の鋼板の表面上に、本発明の接着剤を塗布する。この際、塗布した接着剤の皮膜を１８０℃以上、好ましくは２００〜２３０℃の温度条件下で焼付けて、乾燥状態の接着層を形成させる。この焼付け乾燥後の接着剤の面上に、ポリオレフィンフィルムを熱ラミネートすることにより製造することができる。この熱ラミネートの際の条件は、ポリオレフィンフィルムや接着剤の種類より異なるが、例えば、圧力１．０〜５．０ｋｇ／ｃｍ^２、ラミネート温度１８０〜２２０℃、及びライン速度５〜２０ｍ／分で実施することができる。
【００５１】
【実施例】
以下、実施例によって本発明を具体的に説明するが、これらは本発明の範囲を限定するものではない。以下の「製造例」、「実施例」、「比較例」、及び「物性評価」において、「部」及び「％」は、特に断らない限り、重量により、水酸基価及び酸価の単位は、それぞれ「ｍｇＫＯＨ／ｇ」である。
【製造例１】
反応釜内を窒素ガスで満たした後、メチルエチルケトン（ＭＥＫ）５５６部を仕込み、続いて、水酸基含有化合物成分（Ｐ）として、ポリエステルポリオール（ｐ１）（バイロンＧＫ６４０；線形飽和共重合ポリエステル樹脂；Ｔｇ＝７９℃；数平均分子量（Ｍｎ）＝１８０００；水酸基価＝５；酸価＜４；東洋紡社製）固形分２５４部相当量と水酸基含有シリコーン（ｐ２）（ＫＲ−２１６；水酸基価＝１７０；２５℃で固体；信越化学工業社製）固形分３．２部相当量とを仕込み、５０〜６０℃程度にまで加熱し、攪拌下に溶解させ、続いて、触媒として、ジブチルスズジラウレート固形分０．１部相当量と２，４，６−トリ（ジメチルアミノメチル）フェノール固形分０．０２部相当量とを仕込んだ。溶解させた後、ポリイソシアネート化合物（Ｑ）（タケネートＤ−１７０Ｎ；分子量＝５０４；ＮＣＯ％＝２１％；ヘキサメチレンジイソシアネート三量体（ＮＣＯ末端プレポリマー）；三井武田ケミカル社製）固形分７０．３部相当量を仕込み、８０℃に加熱し、前記水酸基含有化合物成分（Ｐ）の水酸基と前記ポリイソシアネート化合物（Ｑ）のＮＣＯ基とを３時間反応させ、ポリエステルポリウレタンを生成させた。この反応におけるＮＣＯ／ＯＨ比は、約１０であった。その後、得られたポリエステルポリウレタン中に残存する未反応ＮＣＯ基をブロックさせるために、温度を６０℃に冷却し、ブロック化剤としてメチルエチルケトンオキシム３０．２部を滴下した。その際、発熱に注意し、反応液の温度を６０〜６２℃に維持した。ブロック化剤の滴下が終了してから３０分間６０℃で放置して安定化させた。その後、シクロヘキサノン８６部を仕込み、４０℃に冷却し、固形分３６％のブロック化イソシアネート基含有ポリエステルポリウレタン（ａ１）を得た。
【００５２】
【製造例２】
反応釜内を窒素ガスで満たした後、メチルエチルケトン（ＭＥＫ）４８８部を仕込み、続いて、水酸基含有化合物成分（Ｐ）として、ポリエステルポリオール（ｐ１）（バイロンＧＫ６４０；東洋紡社製）固形分２０８部相当量と水酸基含有シリコーン（ｐ２）（ＫＲ−２１６；信越化学工業社製）固形分２．５部相当量と、水酸基含有エポキシ樹脂（ｐ３）（ＡＥＲ２６００；ジャパンエポキシレジン社製）固形分１３部相当量とを仕込み、５０〜６０℃程度にまで加熱し、攪拌下に溶解させ、続いて、触媒として、ジブチルスズジラウレート固形分０．１部相当量と２，４，６−トリ（ジメチルアミノメチル）フェノール固形分０．０２部相当量とを仕込んだ。溶解させた後、ポリイソシアネート化合物（Ｑ）（タケネートＤ−１７０Ｎ；三井武田ケミカル社製）固形分５７．４部相当量を仕込み、８０℃に加熱し、前記水酸基含有化合物成分（Ｐ）の水酸基と前記ポリイソシアネート化合物（Ｑ）のＮＣＯ基とを３時間反応させ、ポリエステルポリウレタンを生成させた。この反応におけるＮＣＯ／ＯＨ比は、約１０であった。その後、得られたポリエステルポリウレタン中に残存する未反応ＮＣＯ基をブロックさせるために、温度を６０℃に冷却し、ブロック化剤としてメチルエチルケトンオキシム２８．９部を滴下した。その際、発熱に注意し、反応液の温度を６０〜６２℃に維持した。ブロック化剤の滴下が終了してから３０分間６０℃で放置して安定化させた。その後、シクロヘキサノン１０９部を仕込み、４０℃に冷却し、固形分３１％のブロック化イソシアネート基含有ポリエステルポリウレタン（ａ２）を得た。
【００５３】
【製造例３】
前記製造例１において水酸基含有化合物成分（Ｐ）として用いたポリエステルポリオール（ｐ１）（バイロンＧＫ６４０；東洋紡社製）に代えて、ポリエステルポリオール（ｐ１）〔バイロンＧＫ８８０；線形飽和共重合ポリエステル；Ｔｇ＝８４℃；数平均分子量（Ｍｎ）＝１８０００；水酸基価＝５；東洋紡社製〕を用いること以外は、前記製造例１の操作を繰り返すことにより、固形分３６％のブロック化イソシアネート基含有ポリエステルポリウレタン（ａ３）を得た。なお、ポリエステルポリウレタン生成反応におけるＮＣＯ／ＯＨ比は、約１０であった。
【００５４】
【製造例４】
前記製造例２において水酸基含有化合物成分（Ｐ）として用いた水酸基含有エポキシ樹脂（ｐ３）（ＡＥＲ２６００；ジャパンエポキシレジン社製）の仕込量を固形分２０部相当量に代えること以外は、前記製造例２の操作を繰り返すことにより、固形分３１％のブロック化イソシアネート基含有ポリエステルポリウレタン（ａ４）を得た。なお、ポリエステルポリウレタン生成反応におけるＮＣＯ／ＯＨ比は、約１０であった。
【００５５】
【製造例５】
前記製造例１において水酸基含有化合物成分（Ｐ）としてポリエステルポリオール（ｐ１）（バイロンＧＫ６４０；東洋紡社製）のみを用いること以外は、前記製造例１の操作を繰り返すことにより、固形分３６％のブロック化イソシアネート基含有ポリエステルポリウレタン（ａ５）を得た。なお、ポリエステルポリウレタン生成反応におけるＮＣＯ／ＯＨ比は、約１０であった。
【００５６】
【製造例６】
反応釜内を窒素ガスで満たした後、メチルエチルケトン（ＭＥＫ）５４６部、及びポリエステルポリオール（ｐ１）（バイロンＧＫ６４０；東洋紡社製）固形分２００部相当量を仕込み、５０℃に加熱して溶解させた後、４０℃に冷却し、ヘキサメチレンジイソシアネート（ＨＤＩ）トリマーのＭＥＫオキシムブロック化合物（住友バイエルンウレタン社製；固形分７５％）１０７．６部を仕込み攪拌した。こうして、固形分３６％のポリエステル・ブロック化イソシアネート混合物を得た。前記生成反応におけるＮＣＯ／ＯＨ比は、約１０であった。
【００５７】
【実施例１】
製造例１で得られたブロック化イソシアネート基含有ポリエステルポリウレタン（ａ１）１００部に、溶媒としてのシクロヘキサノン１６．５部を仕込み、ノボラック型エポキシ樹脂（ｂ２）（アラルダイトＥＣＮ１２７３；分子量４４０；旭化成エポキシ社製）固形分１．１６部相当量、リン酸エポキシエステル樹脂（ｂ１）（ＤＥＲ６２１−ＥＢ５０；ダウ・ケミカル日本社製；固形分５０％品）０．８３部、無水マレイン酸変性ポリオレフィン樹脂分散体（Ｃ）（東洋インキ製造社製；固形分９．５％品）７２．７部を順次仕込み、続いて、ジブチルスズジラウレート固形分０．０１部相当量を仕込み、よく攪拌して溶解させた。４０℃以下に冷却し、シクロヘキサノンで固形分２０％に調整して、本発明による接着剤を得た。
【００５８】
【実施例２】
製造例２で得られたブロック化イソシアネート基含有ポリエステルポリウレタン（ａ２）１００部に、溶媒としてシクロヘキサノン３．５部、リン酸エポキシエステル樹脂（ｂ１）（ＤＥＲ６２１−ＥＢ５０；ダウ・ケミカル日本社製；固形分５０％品）０．９９部、無水マレイン酸変性ポリオレフィン樹脂分散体（Ｃ）（東洋インキ製造社製；固形分９．５％品）８９．５部を順次仕込み、ジブチルスズジラウレート固形分０．０１部相当量を仕込み、よく攪拌して溶解させた。４０℃以下に冷却し、シクロヘキサノンで固形分２０％に調整して、本発明による接着剤を得た。
【００５９】
【実施例３】
製造例３で得られたブロック化イソシアネート基含有ポリエステルポリウレタン（ａ３）１００部に、溶媒としてシクロヘキサノン１６．５部を仕込み、ノボラック型エポキシ樹脂（ｂ２）（アラルダイトＥＣＮ１２７３；旭化成エポキシ社製）固形分１．１６部相当量、リン酸エポキシエステル樹脂（ｂ１）（ＤＥＲ６２１−ＥＢ５０；ダウ・ケミカル日本社製；固形分５０％品）０．８３部、無水マレイン酸変性ポリオレフィン樹脂分散体（Ｃ）（東洋インキ製造社製；固形分９．５％品）７２．７部を順次仕込み、ジブチルスズジラウレート固形分０．０１部相当量を仕込みよく攪拌して溶解させた。４０℃以下に冷却し、シクロヘキサノンで固形分２０％に調整して、本発明による接着剤を得た。
【００６０】
【実施例４】
製造例１で得られたブロック化イソシアネート基含有ポリエステルポリウレタン（ａ１）１００部に、シクロヘキサノン５部を仕込み、ノボラック型エポキシ樹脂（ｂ２）（アラルダイトＥＣＮ１２７３；旭化成エポキシ社製）固形分１．１６部相当量、リン酸エポキシエステル樹脂（ｂ１）（ＤＥＲ６２１−ＥＢ５０；ダウ・ケミカル日本社製；固形分５０％品）０．８３部、酸変性ポリオレフィン樹脂分散体（Ｃ）（東洋インキ製造社製；固形分９．５％品）６４部を順次仕込み、ジブチルスズジラウレート固形分０．０１部相当量を仕込みよく攪拌して溶解させた。４０℃以下に冷却し、シクロヘキサノンで固形分２０％に調整して、本発明による接着剤を得た。
【００６１】
【実施例５】
製造例４で得られたブロック化イソシアネート基含有ポリエステルポリウレタン（ａ４）１００部に、溶媒としてシクロヘキサノン３５部を仕込み、リン酸エポキシエステル樹脂（ｂ１）（ＤＥＲ６２１−ＥＢ５０；ダウ・ケミカル日本社製；固形分５０％品）９．９部、無水マレイン酸変性ポリオレフィン樹脂分散体（Ｃ）（東洋インキ製造社製；固形分９．５％品）８９．５部を順次仕込み、ジブチルスズジラウレート固形分０．１部相当量を仕込みよく攪拌して溶解させた。４０℃以下に冷却し、シクロヘキサノンで固形分２０％に調整して、本発明による接着剤を得た。
【００６２】
【比較例１】
製造例５で得られたブロック化イソシアネート基含有ポリエステルポリウレタン（ａ５）１００部に、溶媒としてシクロヘキサノン１６．５部を仕込み、ノボラック型エポキシ樹脂（ｂ２）（アラルダイトＥＣＮ１２７３；旭化成エポキシ社製）固形分１．１６部相当量、リン酸エポキシエステル樹脂（ｂ１）（ＤＥＲ６２１−ＥＢ５０；ダウ・ケミカル日本社製；固形分５０％品）０．８３部、無水マレイン酸変性ポリオレフィン樹脂分散体（Ｃ）（東洋インキ製造社製；固形分９．５％品）７２．７部を順次仕込み、続いて、ジブチルスズジラウレート固形分０．０１部相当量を仕込み、よく攪拌して溶解させた。４０℃以下に冷却し、シクロヘキサノンで固形分２０％に調整して、比較用接着剤を得た。
【００６３】
【比較例２】
製造例６で得られたポリエステル・ブロック化イソシアネート混合物１００部に、シクロヘキサノン８部を仕込み、ノボラック型エポキシ樹脂（ｂ２）（アラルダイトＥＣＮ１２７３；旭化成エポキシ社製）固形分１．１６部相当量、リン酸エポキシエステル樹脂（ｂ１）（ＤＥＲ６２１−ＥＢ５０；ダウ・ケミカル日本社製；固形分５０％品）１．０５部、酸変性ポリオレフィン樹脂分散体（Ｃ）（東洋インキ製造社製；固形分９．５％品）７２．７部を順次仕込み、ジブチルスズジラウレート固形分０．０３部相当量を、及び２，４，６−トリ（ジメチルアミノメチル）フェノール固形分０．０１部相当量を仕込みよく攪拌して溶解させた。４０℃以下に冷却し、シクロヘキサノンで固形分２０％に調整して、比較用接着剤を得た。
【００６４】
【比較例３】
製造例５で得られたブロック化イソシアネート基含有ポリエステルポリウレタン（ａ５）１００部に、溶媒としてシクロヘキサノン１６．５部を仕込み、水酸基含有シリコーン（ｐ２）（ＫＲ−２１６；２５℃で固体；信越化学工業社製）０．３部、ノボラック型エポキシ樹脂（ｂ２）（アラルダイトＥＣＮ１２７３；旭化成エポキシ社製）固形分１．１６部相当量、リン酸エポキシエステル樹脂（ｂ１）（ＤＥＲ６２１−ＥＢ５０；ダウ・ケミカル日本社製；固形分５０％品）０．８３部、無水マレイン酸変性ポリオレフィン樹脂分散体（Ｃ）（東洋インキ製造社製；固形分９．５％品）７２．７部を順次仕込み、続いて、ジブチルスズジラウレート固形分０．０１部相当量を仕込み、よく攪拌して溶解させた。４０℃以下に冷却し、シクロヘキサノンで固形分２０％に調整して、比較用接着剤を得た。
【００６５】
【比較例４】
ポリオレフィンラミネート鋼板用接着剤〔エポキシウレタン系樹脂及び無水マレイン酸変性ポリオレフィン樹脂分散体（Ｃ）系接着剤；東洋インキ製造社製〕をシクロヘキサノンで固形分２０％に調整して、比較用接着剤を得た。
【００６６】
【比較例５】
ポリオレフィンラミネート鋼板用接着剤（エポキシウレタン系樹脂、無水マレイン酸変性ポリオレフィン樹脂分散体（Ｃ）及びストロンチウムクロメート系接着剤；東洋インキ製造社製）をシクロヘキサノンで固形分２０％に調整して、比較用接着剤を得た。
【００６７】
【物性評価】
（１）試験板の製造
本発明の接着剤及び比較用接着剤の各種物性を評価するための試験板を以下の方法で製造した。すなわち、亜鉛メッキ鋼鈑（厚さ＝０．５ｍｍ）に、乾燥塗膜が４μｍになるようにバーコーターで接着剤を塗布した。その際、亜鉛メッキ鋼鈑の一方の末端部１０ｍｍの部分には、接着剤を塗布しない帯状部分を用意した（後述の図１の接着剤非塗布帯状部分１２ａ参照）。前記の接着剤非塗布帯状部分を進行方向の後方にして、オーブン（２００℃のコンベアー付赤外線オーブン）に入れて１００秒間加熱し、その加熱工程の終了直後に、ポリプロピレンフィルム（厚さ＝１５０μｍ）をラミネーターにより５ｋｇ／ｃｍ^２の圧力でラミネートし、その直後に、水槽に入れて急冷させ、ラミネート鋼板を得た。前記のラミネート操作の際には、前記の接着剤非塗布帯状部分の上にもポリプロピレンフィルムを延長させ、更に、前記鋼鈑が存在しない部分にもポリプロピレンフィルムを延長させた（後述の図１の１１ｂ参照）。なお、ラミネート鋼板を安定化させるために１昼夜放置し、得られた試験板を用いて評価試験を実施した。
【００６８】
（２）常態剥離強度
前項（１）で得られた試験板から、最初に、図１（模式的側面図）に示すような小片１０を切り出した。この小片１０は、幅３０ｍｍ及び長さ１６０ｍｍのポリプロピレンフィルム１１と、幅３０ｍｍ及び長さ６０ｍｍの鋼板１２とからなり、鋼板１２の端部１２ａは、接着剤非塗布帯状部分であるので、ラミネート部分１１ａは、ポリプロピレンフィルムの一方の端部で、幅３０ｍｍ及び長さ５０ｍｍの部分であり、ポリプロピレンフィルム１１の残りの部分１１ｂは、鋼板１２とは接着していないものであった。なお、図１は、ラミネートの態様を示す目的のため、厚さを誇張してある。
【００６９】
続いて、その小片１０から図２（平面図）に示す試験片２０を作成した。すなわち、図１に示す小片１０のポリプロピレンフィルム１１の両側端から５ｍｍの幅で長さ方向にカッターにより２本の切り込み線を入れ、非ラミネート部分では、両側端を取り除いた。その結果、図２に示すように、ポリプロピレンフィルム２１の非ラミネート部分２１ａは、幅２０ｍｍの帯状となった。また、ポリプロピレンフィルム２１の内、鋼板と接着しているラミネート部分２１ｂでは、カッターの刃先が鋼鈑表面に到達する程度までポリプロピレンフィルムを切断して、２本の切り込み線２３ａ，２３ｂを形成した。切り込み線２３ａ，２３ｂの間隔は２０ｍｍとなった。なお、鋼板２２は、接着剤非塗布帯状部分２２ａと接着剤塗布部分２２ｂとを含むものであった。
【００７０】
図２に示す試験片２０を引張り試験機に取り付けた。すなわち、鋼板２２の接着剤非塗布帯状部分２２ａの端部Ｘを下部チャックに挟み、ポリプロピレンフィルム２１の非ラミネート部分２１ａの端部Ｙを上部チャックに挟み、非ラミネート部分２１ａの端部Ｙを１８０°方向転換して、５０ｍｍ／分で上部チャックを移動させ、試験板からフィルムを剥がし、その際の強度を測定した。
【００７１】
（３）沸騰水浸漬後剥離強度
図２に示す試験片２０と同じ試験片を製造し、沸騰水に２時間浸漬させてから取り出し、半日間放置した後に、前項（２）の「常態剥離強度」と同じ方法で測定した。
【００７２】
（４）耐湿試験後の剥離強度
図２に示す試験片２０と同じ試験片を製造し、４０℃及び湿度９８％の恒温恒湿機に２週間放置してから取り出し、半日間放置した後に、前項（２）の「常態剥離強度」と同じ方法で測定した。
【００７３】
（５）常態スクラッチ−エリクセン試験
前項（１）で製造した試験板から、６０ｍｍ×６０ｍｍの寸法にカットしたラミネート試験片を製造し、図３（模式的斜視図）に示すように、ラミネート試験片の鋼板３２の上にラミネートされているポリプロピレンフィルム３１にカッターで、４本の切り込み線３３ａ，３３ｂ，３３ｃ，３３ｄを入れてスクラッチ試験片３０を製造した。スクラッチ試験片３０において、１対の平行な２本の切り込み線３３ａ，３３ｂと、もう１対の平行な２本の切り込み線３３ｃ，３３ｄとを直行させ、それらの間隔をそれぞれ５ｍｍとし、中央部に５ｍｍ×５ｍｍの中央頭部３４を形成させた。また、各切り込み線３３ａ，３３ｂ，３３ｃ，３３ｄは、カッターの刃先が鋼鈑表面に到達する程度までポリプロピレンフィルム３１を切断した。なお、図３は、ラミネートの態様や切り込み線の形成状態を模式的に示す目的であるため、鋼板及びフィルムの厚さや切り込み線の間隔などを誇張してある。
続いて、このスクラッチ試験片３０をエリクセン試験機に取付け、スクラッチ試験片３０の鋼板３２の中央部表面に、エリクセン試験機の押出し用半球体の頂上部を当て、鋼板３２側からポリプロピレンフィルム３１の方向に向かって、押出し用半球体を７ｍｍ押出し、スクラッチ試験片３０の中央頭部３４を中心に半球状に盛り上げた。盛り上げられた中央頭部３４におけるポリプロピレンフィルムの剥がれ状態を目視で判断した。
【００７４】
（６）スクラッチ−エリクセン後の耐熱試験
前項（５）で製造したエリクセン試験後の試験片を、１５０℃の熱風オーブンに１時間放置した後、フィルムの剥がれ状態を目視で判断した。
【００７５】
（７）沸騰水浸漬後のスクラッチ−エリクセン試験
前項（５）で製造したラミネート試験片を、沸騰水に２時間浸漬させてから、半日放置した後に、前項（５）の「エリクセン試験」と同様の操作によって４本の切り込み線３３ａ，３３ｂ，３３ｃ，３３ｄをカッターで形成し、エリクセン試験機で７ｍｍ押出し、中央頭部におけるポリプロピレンフィルムの剥がれ状態を目視で判断した。
【００７６】
（８）スクラッチ−エリクセン後の塩水噴霧試験
図３に示すスクラッチ試験片３０を、エリクセン試験機で６ｍｍ押出した後、３５℃及び塩水濃度５％の塩水噴霧試験機に入れ、４８時間後に取り出し、その試験片の中央頭部におけるポリプロピレンフィルムの剥がれ状態を目視で判断した。
【００７７】
（９）延伸ノッチ試験
前項（１）で得られた試験板を、図４（平面図）に示すように、ラミネート方向（図４の矢印Ａの方向）が幅方向となるように、幅３０ｍｍ及び長さ１２０ｍｍにカットし、延伸ノッチ試験片４０を製造した。その延伸ノッチ試験片４０のラミネートフィルム４１上に中心線ｃを描き、その中心線ｃから両端側に２５ｍｍ離れた位置に、それぞれ平行線ａ，ｂを描いた。また、ラミネートフィルム４１を担持している亜鉛メッキ鋼板の表面において、前記中心線ｃに相当する部分にも中心線を描いた。
次に、アムスラー試験機でこの延伸ノッチ試験片４０を両端（図４の矢印Ｂ及び矢印Ｃの方向）から引っ張り、中央帯状部（平行線ａ，ｂ間）の幅（５０ｍｍ）が幅６０ｍｍとなるように２０％延伸させた。続いて、前記中心線ｃに沿って、カッターの刃先が鋼鈑表面に到達する程度までポリプロピレンフィルムを切断して切り込み線を形成した。
続いて、図５（模式的側面図）に示すように、折り曲げ試験機に、引っ張り処理後の延伸ノッチ試験片４０’のラミネートフィルム４１側の面が表側になり、亜鉛メッキ鋼板４２が裏側にくるように取り付け、亜鉛メッキ鋼板４２の中央部に支柱棒５５（直径＝２ｍｍ）を置き、前記中心線ｃの切り込み線が折り曲げの際の頂点となるように、図５の矢印Ｄの方向にノッチ曲げを行い、亜鉛メッキ鋼板４２の側の表面が相互に完全に密着するまで曲げた。その延伸ノッチ試験片４０’において、ラミネートフィルム４１上に前記中心線ｃにそって作成した切り込み線の剥がれ状態を目視で判断した。
【００７８】
（１０）耐熱延伸ノッチ試験
前項（９）の延伸ノッチ試験片を、１５０℃の熱風オーブンに１時間放置した後、その試験片におけるフィルムの剥がれ状態を目視で判断した。
【００７９】
（１１）判断基準
剥離強度は、単位（Ｎ／２０ｍｍ）で表し、エリクセン試験及び延伸ノッチ試験の評価は、以下の５段階で行った。
◎：優、
◎⁻：やや優、
○：良、
△：可、
×：不可。
結果を表１に示す。
【００８０】
【表１】

【００８１】
【発明の効果】
本発明の接着剤を用いると、ポリオレフィンフィルムなどの難接着性樹脂フィルムを鋼板にラミネートした場合でも、ラミネート加工後に優れた耐熱性を示すと共に、耐沸水性試験後においても優れた接着力が確保される。特に、酸変性ポリオレフィン樹脂を単独で使用する場合と比較すると、加工後の耐熱性が著しく向上すると共に、耐沸水性試験後における接着力を極めて良好に確保することができる。
また、本発明の接着剤は、二液型ではなく一液型であるので、作業性の面で有利であり、しかも、一液型であるにもかかわらず、経時安定性が良好である。
更に、本発明の接着剤を用いると、特に難接着性樹脂フィルム、例えば、ポリオレフィンフィルムを鋼板にラミネートする場合に、コロナ放電処理やプライマー処理などの前処理が不要である。
【図面の簡単な説明】
【図１】本明細書の実施例の剥離試験用の試験片を製造するための小片の模式的側面図である。
【図２】本明細書の実施例の剥離試験用の試験片の平面図である。
【図３】本明細書の実施例の物性評価に用いるスクラッチ試験片の模式的斜視図である。
【図４】本明細書の実施例の物性評価に用いる延伸ノッチ試験片の平面図である。
【図５】図５の延伸ノッチ試験片を折り曲げ試験機に取り付けて折り曲げる状態を示す模式的側面図である。
【符号の説明】
１０・・・試験板小片；
１１，２１，３１，４１・・・ポリプロピレンフィルム；
１２，２２，３２，４２・・・鋼板；
２０・・・試験片；１１ｂ，２１ａ・・・非ラミネート部分；
１１ａ，２１ｂ・・・ラミネート部分；
２３ａ，２３ｂ，３３ａ，３３ｂ，３３ｃ，３３ｄ・・・切り込み線；
１２ａ，２２ａ・・・接着剤非塗布帯状部分；２２ｂ・・・接着剤塗布部分；
３０・・・スクラッチ試験片；３４・・・中央頭部；
４０・・・延伸ノッチ試験片；５５・・・支柱棒。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an adhesive, a method for producing the adhesive, and a plastic film-laminated steel sheet. By using the adhesive of the present invention, a laminate of a plastic film and a steel plate can be obtained.
[0002]
[Prior art]
Laminated steel sheets made by bonding a plastic film with printed or embossed surface to the steel sheet are used for home appliance cases and interior / exterior building materials for homes, etc., and as a material with enhanced design and luxury compared to conventional metal coating. It's being used. These laminated steel sheets are generally manufactured by applying an adhesive to a steel sheet and laminating a plastic film.
As a material for the plastic film, for example, polyvinyl chloride has been widely and conventionally used. However, as is well known, polyvinyl chloride is one of the environmental problems because it contains chlorine. Also, a laminated steel sheet using a polyolefin film is known as an alternative material having the same performance as the polyvinyl chloride laminated steel sheet.
As a conventional adhesive used when laminating a polyvinyl chloride film to a steel sheet, for example, an epoxy resin and an amino resin adhesive, a polyester polyol and a polyisocyanate resin adhesive are known, and a one-pack type adhesive is used. And two-pack type. When these materials are used to laminate a polyvinyl chloride film to a steel sheet, required physical properties are generally achieved. However, since the polyolefin film is a hardly-adhesive material, there is a problem that if the above-mentioned adhesive for laminating a polyvinyl chloride film is used as it is, poor adhesion occurs.
[0003]
As an adhesive between the synthetic resin film and the metal material, for example, a composition in which a polyester polyol and a polyisocyanate compound are combined is known. However, since this type of adhesive is generally of a two-part type, it has poor workability and requires aging after bonding. One-part adhesives using a blocked polyisocyanate are also known, but require a long heat treatment due to poor curability. For the purpose of solving these disadvantages, an adhesive containing a phosphoric acid-modified epoxy resin is described in JP-A-11-166166 (Patent Document 1). However, when a polyolefin film is laminated on a steel sheet using the adhesive described in the above-mentioned publication, it has been difficult to secure heat resistance after laminating and adhesive strength after a boiling water resistance test.
[0004]
Further, as an adhesive for a polyolefin laminated steel sheet, for example, JP-A-9-1733 (Patent Document 2), JP-A-9-309177 (Patent Document 3), or JP-A-10-44312 ( Patent Document 4) describes an adhesive containing a polyolefin resin modified with maleic anhydride or the like. That is, the above publications (Patent Documents 2 to 4) describe a technique for improving the adhesion between a polyolefin film and a steel sheet by adding an acid-modified polyolefin resin to a polyester resin or an epoxy resin. I have. However, even with these techniques, it has been difficult to ensure heat resistance after laminating a polyolefin film to a steel sheet, adhesion strength after a boiling water resistance test, and the like.
[0005]
[Patent Document 1]
JP-A-11-166166
[Patent Document 2]
JP-A-9-1733
[Patent Document 3]
JP-A-9-309177
[Patent Document 4]
JP-A-10-44312
[0006]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide an excellent heat resistance after laminating, and an excellent adhesive force even after a boiling water resistance test, even when a hardly adherent resin film such as a polyolefin film is laminated on a steel sheet. An object of the present invention is to provide an adhesive secured, a method of manufacturing the adhesive, and a plastic film-laminated steel sheet manufactured by using the adhesive.
[0007]
[Means for Solving the Problems]
The above object is achieved by the present invention
(1) The hydroxyl-containing compound component (P) under the condition that the isocyanate group is excessive relative to the total hydroxyl groups of the hydroxyl-containing compound component (P) containing the polyester polyol (p1) and the hydroxyl-containing silicone compound (p2). Is reacted with a polyisocyanate compound (Q) to obtain a blocked isocyanate group-containing polyester polyurethane (A) obtained by blocking an unreacted isocyanate group of an isocyanate group-containing polyester polyurethane (A ′) with a blocking agent;
(2) an epoxy resin (B);
(3) acid-modified polyolefin resin (C)
Can be solved by an adhesive characterized by containing.
[0008]
Also, the present invention
The hydroxyl group-containing compound component (P) is converted into a polyisocyanate under the condition that the isocyanate group is excessive with respect to the total hydroxyl group of the hydroxyl group-containing compound component (P) containing the polyester polyol (p1) and the hydroxyl group-containing silicone compound (p2) Reacting with a compound (Q) to prepare an isocyanate group-containing polyester polyurethane (A ′), and blocking an unreacted isocyanate group in the isocyanate group-containing polyester polyurethane (A ′) with a blocking agent to form a blocked isocyanate group-containing polyester. Preparing an polyurethane (A), and subsequently mixing the blocked isocyanate group-containing polyester polyurethane (A), an epoxy resin (B), and an acid-modified polyolefin resin (C); It also relates to the manufacturing method.
Further, the present invention also relates to a plastic film-laminated steel sheet obtained by laminating a plastic film and a steel sheet using the above-mentioned adhesive.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The adhesive according to the invention contains a blocked isocyanate polyester polyurethane (A). The blocked isocyanate polyester polyurethane (A) is obtained by reacting the hydroxyl group-containing compound component (P) with the polyisocyanate compound (Q) (under the condition that the amount of the isocyanate group becomes excessive) to obtain the isocyanate group-containing polyester polyurethane (A). '), Followed by blocking the unreacted isocyanate groups of the obtained isocyanate group-containing polyester polyurethane (A') with a blocking agent.
[0010]
The hydroxyl-containing compound component (P) contains a polyester polyol (p1) and a hydroxyl-containing silicone compound (p2) as essential components.
The polyester polyol (p1) is a main component that imparts adhesiveness and flexibility to the adhesive of the present invention.
The polyester polyol (p1) is a thermoplastic resin obtained by condensation of a known polybasic acid and a polyhydric alcohol, and any of a branched saturated thermoplastic resin and a linear saturated thermoplastic resin can be used. However, when the branched saturated type is used, an excessive increase in viscosity may occur, so that the linear saturated type is preferable.
[0011]
The number average molecular weight (Mn) of the polyester polyol (p1) is not particularly limited as long as it can be dissolved in the solvent used, but is preferably 8,000 to 30,000, more preferably 10,000 to 28,000, and most preferably 16,000 to 23,000. It is. When the number average molecular weight of the polyester polyol (p1) is less than 8000, the adhesive strength becomes weak, and for example, the polyester polyol (p1) is easily peeled off when brought into contact with hot water. On the other hand, when the number average molecular weight exceeds 30,000, the solubility in a solvent decreases, and the viscosity of the adhesive increases, so that it is difficult to realize a high solid (state in which the resin solid content is increased).
[0012]
Although the glass transition temperature (Tg) of the polyester polyol (p1) is not particularly limited, it is preferably 50 to 100 ° C, more preferably 65 to 85 ° C. If the glass transition temperature is lower than 50 ° C., the heat resistance may be insufficient, and if it exceeds 100 ° C., the coating film may be too hard, which may affect the processability. The glass transition temperature can be adjusted by appropriately selecting the starting polybasic acids and polyhydric alcohols. Further, the glass transition temperature can be adjusted to an appropriate value by using two or more kinds of polyester polyols (p1) having different glass transition temperatures.
[0013]
The hydroxyl value of the polyester polyol (p1) is not particularly limited as long as the hydroxyl group-containing compound component (P) and the polyisocyanate compound (Q) can be reacted under the condition that the amount of the isocyanate group is excessive. In the case of a linear saturated thermoplastic resin, the hydroxyl value is preferably 20 mgKOH / g or less, more preferably 10 mgKOH / g or less. If the hydroxyl value exceeds 20 mgKOH / g, crosslinking of the coating film may be insufficient or the viscosity may be extremely high. The lower limit of the hydroxyl value is also not particularly limited, but is preferably 2 mgKOH / g or more, more preferably 4 mgKOH / g or more. When the hydroxyl value is less than 2 mgKOH / g, the reactivity with the isocyanate compound (Q) becomes slow, and the adhesion may become insufficient. A particularly preferred range of the hydroxyl value is 5 to 6 mgKOH / g, and within this range, excellent physical properties can be obtained in terms of viscosity, crosslinkability of the coating film, and strength.
[0014]
The acid value of the polyester polyol (p1) is also not particularly limited, but is preferably 7 mgKOH / g or less, more preferably 4 mgKOH / g or less, in order to suppress the reaction with the isocyanate compound (Q). When the acid value exceeds 7 mgKOH / g, a foaming reaction occurs with the isocyanate, and the reaction between the isocyanate and the hydroxyl group is inhibited.
[0015]
Examples of the polybasic acid that can be used for preparing the polyester polyol (p1) include, for example, aromatic polybasic acids such as phthalic acid, isophthalic acid, terephthalic acid, diphenyl-p, p′-dicarboxylic acid, or Diphenyl-m, m'-dicarboxylic acid; or an aliphatic polybasic acid such as succinic acid, adipic acid, azelaic acid, sebacic acid, or dodecanedione.
Examples of the polyhydric alcohol which can be used for preparing the polyester polyol (p1) include, for example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,4-butanediol, 1,3- Examples include butanediol, neopentyl glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, or octamethylene glycol. The polyester polyol (p1) can be prepared by polycondensing the polybasic acid and the polyhydric alcohol at, for example, 200 to 250 ° C.
[0016]
As the polyester polyol (p1), commercially available products can be used, and specifically, Viron GK640 (Mn = 18,000, Tg = 79 ° C., hydroxyl value = 5, acid value <4, linear type), Viron GK880 (Mn = 18,000, Tg = 84 ° C., hydroxyl value = 5, acid value <4, linear type), Byron 300 (Mn = 23000, Tg = 7 ° C., hydroxyl value = 5, acid value <2, linear type) Byron 500 (Mn = 23000, Tg = 4 ° C., hydroxyl value = 5, acid value <2, linear type), Byron 560 (Mn = 19000, Tg = 7 ° C., hydroxyl value = 8, acid value <2, branched Type), or Byron 630 (Mn = 20,000, Tg = 75 ° C., hydroxyl value = 5, acid value = 1, linear type) [manufactured by Toyobo Co., Ltd.]; or UE-3600 (Mn = 20) 00, Tg = 75 ° C., hydroxyl value = 4, acid value = 1) or UE-3690 (Mn = 14000, Tg = 91 ° C., hydroxyl value = 8, acid value = 1) [all manufactured by Unitika Ltd.] And the like. In particular, a preferred commercially available product is Byron GK640 or Byron GK880, and a polyester polyol soluble in methyl ethyl ketone (MEK), which has a characteristic value equivalent to that of Byron GK640 or Byron GK880 can also be suitably used. .
[0017]
The hydroxyl-containing compound component (P) contains the hydroxyl-containing silicone compound (p2) as an essential component as described above. This hydroxyl group-containing silicone compound (p2) has an effect of improving the heat resistance of the adhesive layer obtained by the adhesive of the present invention.
As the hydroxyl group-containing silicone compound (p2) that can be used in the present invention, either a liquid or solid compound at room temperature (for example, 25 ° C) can be used, but a hydroxyl group-containing silicone compound that is solid at 25 ° C is preferable. . In addition, even if the liquid silicone compound in the adhesive reacts with the isocyanate as compared with the solid silicone compound, the hydroxyl-containing silicone compound liquid at 25 ° C. causes the silicone portion to float on the adhesive surface due to the heat, and the silicone compound reacts with the film. Although there is a possibility that adhesion may be inhibited, when a solid silicone compound is used, excellent heat resistance can be obtained.
[0018]
The hydroxyl value of the hydroxyl-containing silicone compound (p2) solid at 25 ° C is not particularly limited, but is preferably 300 mgKOH / g or less, more preferably 100 to 200 mgKOH / g. When the hydroxyl value exceeds 300 mgKOH / g, poor adhesion to a plastic film may occur, and when it is less than 100 mgKOH / g, poor heat resistance may occur. The softening point of the hydroxyl-containing silicone compound (p2) that is solid at 25 ° C is not particularly limited, but is preferably 40 to 100 ° C, and more preferably 60 to 80 ° C. When the softening point is lower than 40 ° C., the material may become liquid instead of solid. If the temperature exceeds 100 ° C., the coating film may be too hard, resulting in poor workability.
[0019]
As the hydroxyl group-containing silicone compound (p2) which is solid at 25 ° C., a commercially available product can be used, and specifically, KR-216 (manufactured by Shin-Etsu Chemical Co., Ltd .; softening point = 75 ° C.) is preferable. Further, those having characteristic values equivalent to the above-mentioned KR-216 can also be suitably used.
[0020]
The hydroxyl group-containing compound component (P) may further contain a hydroxyl group-containing epoxy resin (p3) in some cases, in addition to the polyester polyol (p1) and the hydroxyl group-containing silicone compound (p2). When the hydroxyl group-containing epoxy resin (p3) is used, the adhesiveness of the adhesive of the present invention can be improved.
Examples of the hydroxyl group-containing epoxy resin (p3) include a bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin, and a bisphenol A type epoxy resin is particularly preferable. Further, an epoxy resin that is liquid at room temperature (for example, 25 ° C.) is preferable. When a liquid epoxy resin [for example, Epicoat 828] is used as the hydroxyl group-containing epoxy resin (p3), the hydroxyl group can be reacted with the isocyanate group of the polyisocyanate compound (Q). However, when a solid epoxy resin [e.g., Epicoat 1001] is used as the hydroxyl group-containing epoxy resin (p3), gelation occurs during the reaction with the polyisocyanate compound (Q), making it difficult to react.
The number average molecular weight of the hydroxyl group-containing epoxy resin (p3) is not particularly limited, but is preferably 200 to 2,000, more preferably 200 to 1500, and most preferably 250 to 1000. When the number average molecular weight exceeds 2,000, the coating film becomes hard and processing may be defective.
[0021]
As the hydroxyl group-containing epoxy resin (p3), a commercially available product can be used. Examples of commercially available products include Epicoat 1001, Epicoat 828 (manufactured by Japan Epoxy Resin Co., Ltd.), Araldite AER2600, and Araldite 6021 (Asahi Kasei Epoxy Co., Ltd.).
[0022]
In the hydroxyl group-containing compound component (P), the weight ratio (p1 / p2) of the polyester polyol (p1) and the hydroxyl group-containing silicone compound (p2) is preferably from 97/3 to 99.5 / 0. 5, more preferably 98.5 / 1.5 to 99.5 / 0.5. When the weight ratio (p1 / p2) is in the range of 97/3 to 99.5 / 0.5, appropriate coating film performance (for example, heat resistance) can be obtained. However, when the amount of the hydroxyl-containing silicone compound (p2) in the hydroxyl-containing compound component (P) is less than 0.5% by weight, heat resistance may be deteriorated, and the hydroxyl-containing silicone compound (p2) may be deteriorated. If the amount exceeds 3% by weight, the coating film may be too hard and the processability may be reduced.
[0023]
In addition, when the hydroxyl group-containing compound component (P) further contains a hydroxyl group-containing epoxy resin (p3) in addition to the polyester polyol (p1) and the hydroxyl group-containing silicone compound (p2), Is preferably 3/97 to 8/92, more preferably 5/95 to 7/93. If the ratio of the hydroxyl group-containing epoxy resin (p3) exceeds 8% by weight, poor adhesion to a steel sheet may occur, and the ratio of the hydroxyl group-containing epoxy resin (p3) may be less than 3% by weight. Even so, poor contact with the steel sheet may occur.
[0024]
In the present invention, as the polyisocyanate compound (Q) to be reacted with the hydroxyl group-containing compound component (P), any polyisocyanate compound prepared by adding a diisocyanate compound to a polyhydric alcohol can be used. As the polyhydric alcohol, particularly, a trihydric alcohol (for example, trimethylolpropane) or a tetrahydric alcohol (for example, pentaerythritol) can be given.
[0025]
Further, as the isocyanate compound to be added to the polyhydric alcohol, known aromatic isocyanate compounds, aliphatic isocyanate compounds, and / or alicyclic isocyanate compounds can be used. Aliphatic or alicyclic isocyanate compounds are preferred from the viewpoint of excellent hygiene and no discoloration or coloring.
[0026]
Examples of the aliphatic isocyanate compound include hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, and xylylene diisocyanate. Examples of the alicyclic isocyanate compound include isophorone diisocyanate, methylcyclohexane diisocyanate, lysine diisocyanate, and cyclohexane-1,4-diisocyanate. Further, as the aromatic isocyanate compound, tolylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl diisocyanate, tetraalkyl Examples thereof include diphenylmethane isocyanate, dialkyldiphenylmethane diisocyanate, 1,3′-phenylene diisocyanate, and 1,4′-phenylene diisocyanate. However, aromatic isocyanate compounds are excellent in physical properties, but are highly toxic, and thus require attention to work hygiene.
[0027]
As the polyisocyanate compound (Q), isocyanurate, which is a trimer of isocyanate, is preferable from the viewpoint of heat resistance and the like. For example, hexamethylene diisocyanate (HDI) trimer is particularly preferred from the viewpoint of reactivity and heat resistance. As the polyisocyanate compound (Q), a commercially available product can be used, and specific examples include Takenate D-170N (solid content: 100%) [manufactured by Mitsui Takeda Chemical Co., Ltd.]. it can.
[0028]
The reaction between the hydroxyl group-containing compound component (P) and the polyisocyanate compound (Q) is carried out under the condition that the amount of the isocyanate group is excessive with respect to the total number of hydroxyl groups of the hydroxyl group-containing compound component (P). I do. The degree of excess is not particularly limited, but the NCO / OH ratio is preferably 1 to 20, and more preferably 5 to 15. If the NCO / OH ratio exceeds 20, workability may be poor, and if it is less than 1, poor adhesion to a steel sheet may occur.
[0029]
The reaction between the hydroxyl-containing compound component (P) and the polyisocyanate compound (Q) can be carried out using a known catalyst. Examples of the catalyst include tin compounds such as dibutyltin dilaurate and dioctyltin dilaurate, and amine compounds such as TEDA and tertiary amine 2,4,6-tri (dimethylaminomethyl) phenol or dimethylaminomethylphenol. These catalysts can be used alone or in combination.
[0030]
The reaction between the hydroxyl-containing compound component (P) and the polyisocyanate compound (Q) can be carried out in any organic solvent, for example, in methyl ethyl ketone. Subsequently, unreacted isocyanate groups of the isocyanate group-containing polyester polyurethane (A ′) prepared by the above reaction are blocked with a blocking agent. As the blocking agent, a known compound such as an alcohol-based, lactam-based, oxime-based, or β-diketone-based blocking agent can be used. Generally, their dissociation temperatures are said to be about 180 ° C. or higher for alcohols, about 160 ° C. for lactams, about 140 ° C. for oximes, and about 100 ° C. for β-diketones. It is preferable to use an oxime-based blocking agent.
[0031]
Alcohol-based and lactam-based blocking agents are considered to have good stability over time, but considering that the preferred lamination temperature when using the adhesive of the present invention is about 200 ° C., complete dissociation at the lamination temperature. Since the temperature difference is small, the oxime-based blocking agent is preferred from the viewpoint of the dissociation temperature. On the other hand, the β-diketone system may have poor stability over time because the dissociation temperature is too low. From these points, it is preferable to use an oxime system, and particularly, methyl ethyl ketone oxime can be suitably used.
[0032]
The adhesive of the present invention comprises the above blocked isocyanate group-containing polyester polyurethane (A) in an amount of preferably 60 to 90% by weight, more preferably 70 to 80% by weight, based on the total solid weight of the adhesive. Can be contained. If the content of the blocked isocyanate group-containing polyester polyurethane (A) exceeds 90% by weight, poor adhesion to a plastic film may occur. If the content is less than 60% by weight, poor adhesion to a steel sheet may occur. Sometimes.
[0033]
The adhesive of the present invention contains an epoxy resin (B). By containing the epoxy resin (B), adhesion to a steel sheet, moisture resistance, and boiling water resistance can be imparted. The epoxy resin (B) is not particularly limited, but is preferably an epoxy phosphate resin (b1). By containing the epoxy phosphate resin (b1), it is possible to improve the adhesion to a steel sheet and the moisture resistance. The epoxy phosphate ester resin (b1) is a resin in which the epoxy group reacts with phosphoric acid to open the epoxy group, and the epoxy resin portion and the phosphoric acid portion are bonded by a phosphate ester bond.
[0034]
Preferred epoxy phosphate resin (b1) is represented by the general formula (1):
Embedded image

(Where R ¹ Is an epoxy resin residue)
Or a compound represented by the general formula (2):
Embedded image

(Where R ² And R ³ Is an epoxy resin residue)
It is a compound represented by these.
[0035]
Particularly preferred epoxy phosphate resin (b1) is a compound having a phosphoric acid group and a primary hydroxyl group at the molecular terminal. Particularly preferred epoxy phosphate resin (b1) is represented by the general formula (3):
Embedded image

(Where R ⁴ Is an epoxy resin residue)
It is a compound represented by these.
[0036]
As the epoxy phosphate ester resin (b1), a commercially available product can be used, and specifically, DER621-EB50 [manufactured by Dow Chemical Japan Co., Ltd .; solid content 50%] is preferable. Further, those having characteristic values equivalent to those of the above-mentioned DER621-EB50 can also be suitably used.
[0037]
When the epoxy phosphate resin (b1) is used as the epoxy resin (B), the adhesive of the present invention uses the epoxy phosphate ester resin (b1) and the blocked isocyanate group-containing polyester polyurethane ( It can be contained in an amount of preferably 0.5 to 3.5 parts by weight, more preferably 1.5 to 2.5 parts by weight, based on 100 parts by weight of the solid content of A). When the content of the epoxy phosphate resin (b1) exceeds 3.5 parts by weight, the compatibility with the component (A) becomes poor, and the adhesiveness to a steel plate and a plastic film may be poor. If the amount is less than 0.5 part by weight, the adhesion to a steel sheet and the moisture resistance may be poor.
[0038]
As the epoxy resin (B), a non-phosphoric acid-modified epoxy resin (b2) may be used instead of the epoxy phosphate resin (b1) or in addition to the epoxy phosphate resin (b1). It is preferable to simultaneously contain the latter, that is, (b1) and (b2). Here, the non-phosphate-modified epoxy resin (b2) means an epoxy resin different from the epoxy phosphate ester resin (b1), and means any epoxy resin that has not been modified with phosphoric acid. Therefore, the non-phosphoric acid-modified epoxy resin (b2) can be an epoxy resin (b2-1) containing no hydroxyl group or an epoxy resin (b2-2) containing a hydroxyl group, and has heat resistance (adhesiveness). Since it is preferable from the viewpoint, the epoxy resin (b2-1) containing no hydroxyl group can be suitably used.
[0039]
Further, when a hydroxyl group-free epoxy resin (b2-1) is used as the non-phosphoric acid-modified epoxy resin (b2), the adhesive of the present invention can be provided with heat resistance and adhesiveness to a steel plate. As such a hydroxyl group-free epoxy resin (b2-1), for example, a phenol novolak epoxy resin and / or a cresol novolak epoxy resin can be used, and it is preferable to use a cresol novolak epoxy resin. The number average molecular weight of the phenol novolak epoxy resin or cresol novolak epoxy resin is not particularly limited, but is preferably 300 to 800, more preferably 400 to 600. As the cresol novolak type epoxy resin, a commercially available product can be used. For example, Araldite ECN1273 (manufactured by Asahi Kasei Epoxy Co., Ltd.) is preferably used.
[0040]
The adhesive of the present invention preferably contains 2 to 6 parts by weight of the hydroxyl group-free epoxy resin (b2-1) based on 100 parts by weight of the solid content of the blocked isocyanate group-containing polyester polyurethane (A). More preferably, it can be contained in an amount of 4 to 5 parts by weight. If the content of the hydroxyl group-free epoxy resin (b2-1) exceeds 6 parts by weight, poor workability may occur. If the content is less than 2 parts by weight, heat resistance and poor adhesion to a steel sheet may result. is there. In addition, when contained in an amount of 4 to 5 parts by weight, excellent heat resistance and adhesiveness can be obtained.
[0041]
On the other hand, when a solid epoxy resin [e.g., Epicoat 1001] is used as the above-mentioned hydroxyl group-containing epoxy resin (b2-2), it is simply mixed with the blocked isocyanate group-containing polyester polyurethane (A). The hydroxyl group of the resin (b2-2) does not react with the isocyanate group of the blocked isocyanate group-containing polyester polyurethane (A). However, when the adhesive is heated after coating, the blocked isocyanate groups are deblocked and the free isocyanate groups are reproduced, so that the free isocyanate groups and the hydroxyl groups contained in the solid epoxy resin combine to form an adhesive. Function can be performed.
[0042]
In the adhesive of the present invention, the hydroxyl group-containing epoxy resin (b2-2) is preferably used in an amount of preferably 1 to 7 parts by weight, based on 100 parts by weight of the solid content of the blocked isocyanate group-containing polyester polyurethane (A). Preferably, it can be contained in an amount of 3 to 5 parts by weight. When the content of the hydroxyl group-containing epoxy resin (b2-2) exceeds 7 parts by weight, poor workability may occur. When the content is less than 1 part by weight, poor adhesion to a steel sheet may occur.
[0043]
The adhesive of the present invention further contains an acid-modified polyolefin resin (C). By using the acid-modified polyolefin resin (C), the adhesiveness with a polyolefin can be particularly improved.
The acid-modified polyolefin resin can be prepared, for example, by graft-polymerizing an acid anhydride containing an ethylenically unsaturated group to the polyolefin resin. Examples of the polyolefin resin include polyethylene, polypropylene, an ethylene-propylene copolymer, and an ethylene-vinyl acetate copolymer. Examples of the acid anhydride containing an ethylenically unsaturated group include, for example, maleic anhydride, fumaric anhydride, maleic acid, fumaric acid, and itaconic acid, and maleic anhydride is preferably used. Can be.
Further, as the acid-modified polyolefin resin, a monomer or a mixture of a copolymer of an olefin and an ethylenically unsaturated group-containing carboxylic acid (for example, an ethylene-acrylic acid copolymer or an ethylene-methacrylic acid copolymer) is used. The body can also be used.
[0044]
In the adhesive of the present invention, the content of the acid-modified polyolefin resin (C) is preferably 50/50 to 90 as the solid content ratio (A / C) of the blocked isocyanate group-containing polyester polyurethane (A). / 10, more preferably 75/25 to 80/20. When the content of the acid-modified polyolefin resin (C) is more than 50/50 of the solid content ratio (A / C), poor adhesion to a steel sheet or poor coating property due to an increase in viscosity may occur. If it is less than 90/10, poor adhesion to a plastic film may occur. Further, when the content of the acid-modified polyolefin resin (C) is in the range of 75/25 to 80/20 of the solid content ratio (A / C), a suitable adhesive viscosity is obtained and excellent. Coatability is obtained.
[0045]
The adhesive of the present invention can be prepared by simply mixing the blocked isocyanate group-containing polyester polyurethane (A), the epoxy resin (B), and the acid-modified polyolefin resin (C). it can. The mixing can be performed in an organic solvent, for example, an aliphatic ketone (for example, methyl ethyl ketone) or an alicyclic ketone (for example, cyclohexanone), and an aliphatic ester (for example, ethyl acetate or butyl acetate) is used in combination. You can also.
[0046]
The order of the mixing is not limited. For example, after mixing the blocked isocyanate group-containing polyester polyurethane (A) and the epoxy resin (B), the acid-modified polyolefin resin (C) can be added, or the epoxy resin can be added. After mixing (B) and the acid-modified polyolefin resin (C), the above-mentioned blocked isocyanate group-containing polyester polyurethane (A) can be added, or the above-mentioned blocked isocyanate group-containing polyester polyurethane ( After mixing A) with the acid-modified polyolefin resin (C), the epoxy resin (B) can be added.
[0047]
A plastic film can be laminated on a steel plate using the adhesive of the present invention. The plastic film is not particularly limited, but when the adhesive of the present invention is used, a polyolefin film, which is a poorly adhesive material, can be laminated on a steel plate. Examples of the polyolefin film include polyethylene and polypropylene. The thickness of the polyolefin film that can be laminated is not particularly limited. For example, a film having a thickness of about 500 μm can be used.
[0048]
The steel sheet is not particularly limited, and for example, a general steel sheet base such as a stainless steel base or a galvanized steel base can be used. The galvanization on the surface of the galvanized steel substrate may be, for example, a steel plate as a base material, which may be subjected to pure zinc plating, or one of zinc alloy plating, and further to another Plating may be applied in multiple layers.
[0049]
These steel sheet substrates can be subjected to a base treatment, if necessary. In the case of a stainless steel sheet, although a base treatment is not particularly required, adhesion to a polyolefin film can be further improved by chromate treatment. In some cases, galvanized steel sheets need to be subjected to one or both of phosphate treatment and chromate treatment. By the chromate treatment and / or the phosphoric acid treatment, the adhesion of the polyolefin film to the polyolefin film-laminated steel sheet can be improved. The phosphate treatment and the chromate treatment are not particularly limited, and can be performed by a conventional general method.
[0050]
When manufacturing the polyolefin film-laminated steel sheet of the present invention, the adhesive of the present invention is applied on the surface of the steel sheet. At this time, the applied adhesive film is baked at a temperature of 180 ° C. or higher, preferably 200 to 230 ° C., to form a dry adhesive layer. It can be manufactured by heat laminating a polyolefin film on the surface of the adhesive after baking and drying. The conditions for this heat lamination differ depending on the type of the polyolefin film or the adhesive, but for example, the pressure is 1.0 to 5.0 kg / cm. ² It can be carried out at a laminating temperature of 180 to 220 ° C. and a line speed of 5 to 20 m / min.
[0051]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but these do not limit the scope of the present invention. In the following "Production Examples", "Examples", "Comparative Examples", and "Evaluation of Physical Properties", "parts" and "%" are units of hydroxyl value and acid value by weight unless otherwise specified. Each is “mgKOH / g”.
[Production Example 1]
After filling the inside of the reactor with nitrogen gas, 556 parts of methyl ethyl ketone (MEK) were charged, and subsequently, as a hydroxyl group-containing compound component (P), polyester polyol (p1) (Vylon GK640; linear saturated copolymerized polyester resin; Tg = 79 ° C .; number average molecular weight (Mn) = 18000; hydroxyl value = 5; acid value <4; Toyobo Co., Ltd.) 254 parts equivalent of solid content and hydroxyl group-containing silicone (p2) (KR-216; hydroxyl value = 170; 25) (Solid; manufactured by Shin-Etsu Chemical Co., Ltd.) and equivalent to 3.2 parts of a solid content, heated to about 50 to 60 ° C. and dissolved with stirring, and subsequently, as a catalyst, dibutyltin dilaurate solid content of 0.1 part was added. 1 part equivalent and 2,4,6-tri (dimethylaminomethyl) phenol solid content equivalent to 0.02 part were charged. After dissolution, polyisocyanate compound (Q) (Takenate D-170N; molecular weight = 504; NCO% = 21%; hexamethylene diisocyanate trimer (NCO-terminated prepolymer); manufactured by Mitsui Takeda Chemical Co.) An equivalent amount of 3 parts was charged and heated to 80 ° C. to react the hydroxyl group of the hydroxyl-containing compound component (P) with the NCO group of the polyisocyanate compound (Q) for 3 hours to produce a polyester polyurethane. The NCO / OH ratio in this reaction was about 10. Thereafter, in order to block unreacted NCO groups remaining in the obtained polyester polyurethane, the temperature was cooled to 60 ° C., and 30.2 parts of methyl ethyl ketone oxime was added dropwise as a blocking agent. At this time, the temperature of the reaction solution was maintained at 60 to 62 ° C. while paying attention to heat generation. After the dropping of the blocking agent was completed, the mixture was allowed to stand at 60 ° C. for 30 minutes to be stabilized. Thereafter, 86 parts of cyclohexanone was charged and cooled to 40 ° C. to obtain a blocked isocyanate group-containing polyester polyurethane (a1) having a solid content of 36%.
[0052]
[Production Example 2]
After filling the reactor with nitrogen gas, 488 parts of methyl ethyl ketone (MEK) were charged, and then, as a hydroxyl group-containing compound component (P), a solid content of polyester polyol (p1) (Vylon GK640; manufactured by Toyobo Co., Ltd.) equivalent to 208 parts Amount and equivalent to 2.5 parts of solid content of hydroxyl-containing silicone (p2) (KR-216; manufactured by Shin-Etsu Chemical Co., Ltd.) and 13 parts of solid content of hydroxyl-containing epoxy resin (p3) (AER2600; manufactured by Japan Epoxy Resin Co., Ltd.) Then, the mixture was heated to about 50 to 60 ° C. and dissolved under stirring, and subsequently, as a catalyst, 0.1 parts by weight of dibutyltin dilaurate solid content and 2,4,6-tri (dimethylaminomethyl) A phenol solid content of 0.02 parts was added. After dissolving, the polyisocyanate compound (Q) (Takenate D-170N; manufactured by Mitsui Takeda Chemical Co., Ltd.) was charged with an equivalent amount of 57.4 parts of solid content, heated to 80 ° C., and the hydroxyl group of the hydroxyl group-containing compound component (P) was added. And the NCO group of the polyisocyanate compound (Q) were reacted for 3 hours to produce a polyester polyurethane. The NCO / OH ratio in this reaction was about 10. Thereafter, in order to block unreacted NCO groups remaining in the obtained polyester polyurethane, the temperature was cooled to 60 ° C., and 28.9 parts of methyl ethyl ketone oxime was added dropwise as a blocking agent. At this time, the temperature of the reaction solution was maintained at 60 to 62 ° C. while paying attention to heat generation. After the dropping of the blocking agent was completed, the mixture was allowed to stand at 60 ° C. for 30 minutes to be stabilized. Thereafter, 109 parts of cyclohexanone was charged and cooled to 40 ° C. to obtain a blocked isocyanate group-containing polyester polyurethane (a2) having a solid content of 31%.
[0053]
[Production Example 3]
In place of the polyester polyol (p1) (Vylon GK640; manufactured by Toyobo Co., Ltd.) used as the hydroxyl group-containing compound component (P) in Production Example 1, a polyester polyol (p1) [Vylon GK880; linear saturated copolymerized polyester; Tg = 84 ° C; number average molecular weight (Mn) = 18000; hydroxyl value = 5; manufactured by Toyobo Co., Ltd.], except that a blocked isocyanate group-containing polyester polyurethane having a solid content of 36% (solid content: 36%) was obtained. a3) was obtained. The NCO / OH ratio in the polyester polyurethane formation reaction was about 10.
[0054]
[Production Example 4]
Except that the charged amount of the hydroxyl group-containing epoxy resin (p3) (AER2600; manufactured by Japan Epoxy Resin Co.) used as the hydroxyl group-containing compound component (P) in Production Example 2 was changed to an amount equivalent to 20 parts of solids, By repeating the operation of 2, a blocked isocyanate group-containing polyester polyurethane (a4) having a solid content of 31% was obtained. The NCO / OH ratio in the polyester polyurethane formation reaction was about 10.
[0055]
[Production Example 5]
By repeating the procedure of Production Example 1 except that only the polyester polyol (p1) (Vylon GK640; manufactured by Toyobo Co., Ltd.) was used as the hydroxyl group-containing compound component (P) in Production Example 1, a block having a solid content of 36% was obtained. Thus, an isocyanate group-containing polyester polyurethane (a5) was obtained. The NCO / OH ratio in the polyester polyurethane formation reaction was about 10.
[0056]
[Production Example 6]
After filling the inside of the reaction vessel with nitrogen gas, 546 parts of methyl ethyl ketone (MEK) and 200 parts by weight of polyester polyol (p1) (Vylon GK640; manufactured by Toyobo Co., Ltd.) were added and dissolved at 50 ° C. by heating. Thereafter, the mixture was cooled to 40 ° C., and 107.6 parts of a MEK oxime block compound of hexamethylene diisocyanate (HDI) trimer (manufactured by Sumitomo Bayern Urethane Co .; solid content: 75%) was charged and stirred. Thus, a polyester blocked isocyanate mixture having a solid content of 36% was obtained. The NCO / OH ratio in the production reaction was about 10.
[0057]
Embodiment 1
100 parts of the blocked isocyanate group-containing polyester polyurethane (a1) obtained in Production Example 1 was charged with 16.5 parts of cyclohexanone as a solvent, and a novolak-type epoxy resin (b2) (Araldite ECN1273; molecular weight 440; manufactured by Asahi Kasei Epoxy Corporation) ) A solid content equivalent to 1.16 parts, a phosphoric acid epoxy ester resin (b1) (DER621-EB50; manufactured by Dow Chemical Japan; solid content 50%) 0.83 part, a maleic anhydride-modified polyolefin resin dispersion ( C) 72.7 parts of (manufactured by Toyo Ink Mfg. Co., Ltd., 9.5% solid content) were sequentially charged, followed by 0.01 part of a solid content of dibutyltin dilaurate, which was stirred well and dissolved. After cooling to 40 ° C. or lower, the solid content was adjusted to 20% with cyclohexanone to obtain an adhesive according to the present invention.
[0058]
Embodiment 2
To 100 parts of the blocked isocyanate group-containing polyester polyurethane (a2) obtained in Production Example 2, 3.5 parts of cyclohexanone as a solvent, epoxy phosphate resin (b1) (DER621-EB50; manufactured by Dow Chemical Japan); solid 0.99 parts) and 89.5 parts of maleic anhydride-modified polyolefin resin dispersion (C) (manufactured by Toyo Ink Mfg. Co., Ltd .; 9.5% solid content) were sequentially charged, and the dibutyltin dilaurate solid content was 0.9%. An amount equivalent to 01 parts was charged and dissolved with good stirring. After cooling to 40 ° C. or lower, the solid content was adjusted to 20% with cyclohexanone to obtain an adhesive according to the present invention.
[0059]
Embodiment 3
Into 100 parts of the blocked isocyanate group-containing polyester polyurethane (a3) obtained in Production Example 3, 16.5 parts of cyclohexanone was charged as a solvent, and a novolak-type epoxy resin (b2) (Araldite ECN1273; manufactured by Asahi Kasei Epoxy Co.) was used. 0.83 parts of a phosphoric acid epoxy ester resin (b1) (DER621-EB50; manufactured by Dow Chemical Japan; solid content 50%), a maleic anhydride-modified polyolefin resin dispersion (C) (Toyo) 72.7 parts of a product (manufactured by Ink Manufacturing Co., Ltd .; solid content: 9.5%) were sequentially charged, and 0.01 part of solid content of dibutyltin dilaurate was charged and dissolved with good stirring. After cooling to 40 ° C. or lower, the solid content was adjusted to 20% with cyclohexanone to obtain an adhesive according to the present invention.
[0060]
Embodiment 4
100 parts of the blocked isocyanate group-containing polyester polyurethane (a1) obtained in Production Example 1 was charged with 5 parts of cyclohexanone, and a novolak-type epoxy resin (b2) (Araldite ECN1273; manufactured by Asahi Kasei Epoxy Co.) was equivalent to 1.16 parts of solid content. 0.83 parts of an acid-modified polyolefin resin dispersion (C) (manufactured by Toyo Ink Mfg. Co., Ltd .; solids) (9.5% product), 64 parts were charged in sequence, and 0.01 part of a solid content of dibutyltin dilaurate was charged and dissolved with good stirring. After cooling to 40 ° C. or lower, the solid content was adjusted to 20% with cyclohexanone to obtain an adhesive according to the present invention.
[0061]
Embodiment 5
To 100 parts of the blocked isocyanate group-containing polyester polyurethane (a4) obtained in Production Example 4, 35 parts of cyclohexanone was charged as a solvent, and an epoxy phosphate resin (b1) (DER621-EB50; manufactured by Dow Chemical Japan) was used. 9.9 parts) and 89.5 parts of maleic anhydride-modified polyolefin resin dispersion (C) (manufactured by Toyo Ink Mfg. Co., Ltd .; solid content: 9.5%) were sequentially charged, and dibutyltin dilaurate solid content was 0.9%. An equivalent amount of 1 part was mixed well and dissolved by stirring. After cooling to 40 ° C. or lower, the solid content was adjusted to 20% with cyclohexanone to obtain an adhesive according to the present invention.
[0062]
[Comparative Example 1]
100 parts of the blocked isocyanate group-containing polyester polyurethane (a5) obtained in Production Example 5 was charged with 16.5 parts of cyclohexanone as a solvent, and a novolak-type epoxy resin (b2) (Araldite ECN1273; manufactured by Asahi Kasei Epoxy Co.) was used. Equivalent to 16 parts, 0.83 part of a phosphate epoxy ester resin (b1) (DER621-EB50; manufactured by Dow Chemical Japan; solid content 50%), maleic anhydride-modified polyolefin resin dispersion (C) (Toyo) 72.7 parts of a product (manufactured by Ink Manufacturing Co., Ltd .; solid content: 9.5%) were sequentially charged, followed by 0.01 part of a solid content of dibutyltin dilaurate, which was stirred well and dissolved. After cooling to 40 ° C. or lower, the solid content was adjusted to 20% with cyclohexanone to obtain a comparative adhesive.
[0063]
[Comparative Example 2]
To 100 parts of the polyester-blocked isocyanate mixture obtained in Production Example 6, 8 parts of cyclohexanone was charged, and a novolak-type epoxy resin (b2) (Araldite ECN1273; manufactured by Asahi Kasei Epoxy Co.) was equivalent to 1.16 parts of solid content, phosphoric acid. 1.05 parts of epoxy ester resin (b1) (DER621-EB50; manufactured by Dow Chemical Japan; solid content: 50%); acid-modified polyolefin resin dispersion (C) (manufactured by Toyo Ink Manufacturing Co .; solid content: 9.5) % Product), 72.7 parts of dibutyltin dilaurate solids equivalent to 0.03 parts equivalent, and 2,4,6-tri (dimethylaminomethyl) phenol solids equivalent to 0.01 part equivalent are charged and stirred well. To dissolve. After cooling to 40 ° C. or lower, the solid content was adjusted to 20% with cyclohexanone to obtain a comparative adhesive.
[0064]
[Comparative Example 3]
100 parts of the blocked isocyanate group-containing polyester polyurethane (a5) obtained in Production Example 5 was charged with 16.5 parts of cyclohexanone as a solvent, and the hydroxyl group-containing silicone (p2) (KR-216; solid at 25 ° C; Shin-Etsu Chemical Co., Ltd.) 0.3 parts, novolak type epoxy resin (b2) (Araldite ECN1273; manufactured by Asahi Kasei Epoxy Co.) 1.16 parts equivalent of solid content, phosphate epoxy ester resin (b1) (DER621-EB50; Dow Chemical Japan) 0.83 parts of a maleic anhydride-modified polyolefin resin dispersion (C) (manufactured by Toyo Ink Mfg. Co., Ltd .; 9.5% of solids) was sequentially charged. And dibutyltin dilaurate in an amount equivalent to 0.01 part by solid content, and stirred well to dissolve. After cooling to 40 ° C. or lower, the solid content was adjusted to 20% with cyclohexanone to obtain a comparative adhesive.
[0065]
[Comparative Example 4]
The adhesive for polyolefin-laminated steel sheet [epoxyurethane resin and maleic anhydride-modified polyolefin resin dispersion (C) -based adhesive; manufactured by Toyo Ink Mfg. Co., Ltd.] was adjusted to a solid content of 20% with cyclohexanone, and a comparative adhesive was prepared. Obtained.
[0066]
[Comparative Example 5]
Polyolefin laminated steel sheet adhesive (epoxy urethane resin, maleic anhydride-modified polyolefin resin dispersion (C) and strontium chromate adhesive; manufactured by Toyo Ink Mfg. Co., Ltd.) was adjusted to a solid content of 20% with cyclohexanone for comparison. An adhesive was obtained.
[0067]
【Evaluation of the physical properties】
(1) Production of test plate
Test plates for evaluating various physical properties of the adhesive of the present invention and the comparative adhesive were produced by the following methods. That is, an adhesive was applied to a galvanized steel sheet (thickness = 0.5 mm) with a bar coater so that the dry coating film became 4 μm. At this time, a band-shaped portion to which no adhesive was applied was prepared at one end portion of the galvanized steel sheet at a distance of 10 mm (see the adhesive-uncoated band-shaped portion 12a in FIG. 1 described later). The above adhesive-uncoated band-shaped portion is placed backward in the traveling direction, placed in an oven (infrared oven with a conveyor at 200 ° C.) and heated for 100 seconds. Immediately after the completion of the heating step, a polypropylene film (thickness = 150 μm) 5kg / cm by laminator ² , And immediately thereafter, it was placed in a water tank and rapidly cooled to obtain a laminated steel sheet. During the laminating operation, the polypropylene film was extended also on the adhesive-uncoated strip portion, and further, the polypropylene film was extended on the portion where the steel plate was not present (see FIG. 1 described later). 11b). In order to stabilize the laminated steel sheet, it was left for one day and night, and an evaluation test was performed using the obtained test plate.
[0068]
(2) Normal peel strength
First, a small piece 10 as shown in FIG. 1 (a schematic side view) was cut out from the test plate obtained in the preceding section (1). The small piece 10 is composed of a polypropylene film 11 having a width of 30 mm and a length of 160 mm, and a steel plate 12 having a width of 30 mm and a length of 60 mm. Reference numeral 11a denotes one end of the polypropylene film, which is a portion having a width of 30 mm and a length of 50 mm. The remaining portion 11b of the polypropylene film 11 was not bonded to the steel plate 12. In FIG. 1, the thickness is exaggerated for the purpose of showing the mode of lamination.
[0069]
Subsequently, a test piece 20 shown in FIG. 2 (plan view) was created from the small piece 10. That is, two cut lines were made by a cutter in the length direction with a width of 5 mm from both ends of the polypropylene film 11 of the small piece 10 shown in FIG. 1, and both ends were removed in a non-laminated portion. As a result, as shown in FIG. 2, the non-laminated portion 21a of the polypropylene film 21 became a 20 mm wide band. Further, in the laminated portion 21b of the polypropylene film 21 which is adhered to the steel plate, the polypropylene film was cut until the cutting edge of the cutter reached the steel plate surface to form two cut lines 23a and 23b. The interval between the cut lines 23a and 23b was 20 mm. In addition, the steel plate 22 included an adhesive non-applied strip portion 22a and an adhesive applied portion 22b.
[0070]
The test piece 20 shown in FIG. 2 was attached to a tensile tester. That is, the end portion X of the non-adhesive coated strip portion 22a of the steel plate 22 is sandwiched by the lower chuck, the end portion Y of the non-laminated portion 21a of the polypropylene film 21 is sandwiched by the upper chuck, and the end portion Y of the non-laminated portion 21a is 180 After changing the direction, the upper chuck was moved at 50 mm / min, the film was peeled off from the test plate, and the strength at that time was measured.
[0071]
(3) Peel strength after immersion in boiling water
The same test piece as the test piece 20 shown in FIG. 2 was manufactured, immersed in boiling water for 2 hours, taken out, left for half a day, and measured by the same method as the “normal peel strength” in the above item (2).
[0072]
(4) Peel strength after moisture resistance test
The same test piece as the test piece 20 shown in FIG. 2 was manufactured, left for 2 weeks in a thermo-hygrostat at 40 ° C. and 98% humidity, taken out, and left for half a day. Was measured in the same manner.
[0073]
(5) Normal scratch-Erichsen test
From the test plate manufactured in the preceding paragraph (1), a laminated test piece cut into a size of 60 mm × 60 mm was manufactured, and as shown in FIG. 3 (a schematic perspective view), was laminated on the steel plate 32 of the laminated test piece. Four scratch lines 33a, 33b, 33c, and 33d were cut into the polypropylene film 31 by using a cutter to produce a scratch test piece 30. In the scratch test piece 30, one pair of two parallel cutting lines 33a and 33b and another pair of two parallel cutting lines 33c and 33d are made to go perpendicular to each other, and the interval between them is set to 5 mm. A central head 34 of 5 mm × 5 mm was formed. Further, each of the cut lines 33a, 33b, 33c and 33d cut the polypropylene film 31 until the cutting edge of the cutter reaches the steel plate surface. In addition, since FIG. 3 is for the purpose of schematically showing the form of lamination and the state of formation of the cut lines, the thickness of the steel sheet and the film, the interval between the cut lines, and the like are exaggerated.
Subsequently, the scratch test piece 30 was attached to an Erichsen test machine, and the top of an extruded hemisphere of the Erichsen test machine was applied to the central surface of the steel plate 32 of the scratch test piece 30. The hemisphere for extrusion was extruded 7 mm toward the direction, and was hemispherically raised around the central head 34 of the scratch test piece 30. The peeled state of the polypropylene film on the raised central head 34 was visually determined.
[0074]
(6) Heat resistance test after scratch-Eriksen
After the test piece after the Erichsen test manufactured in the above section (5) was left in a hot air oven at 150 ° C. for 1 hour, the peeling state of the film was visually judged.
[0075]
(7) Scratch-Erichsen test after immersion in boiling water
The laminate test piece manufactured in the preceding section (5) was immersed in boiling water for 2 hours, left for half a day, and then subjected to four cut lines 33a, 33b, 33c and 33d were formed with a cutter, extruded by 7 mm with an Erichsen tester, and the peeling state of the polypropylene film at the central head was visually determined.
[0076]
(8) Salt spray test after scratch-Eriksen
After the scratch test piece 30 shown in FIG. 3 was extruded by 6 mm with an Erichsen tester, the test piece was put into a salt spray tester at 35 ° C. and a salt water concentration of 5%. The peeled state was visually determined.
[0077]
(9) Stretch notch test
As shown in FIG. 4 (plan view), the test plate obtained in the preceding section (1) is cut into a width of 30 mm and a length of 120 mm so that the laminating direction (the direction of arrow A in FIG. 4) is the width direction. Then, a stretch notch test piece 40 was manufactured. A center line c was drawn on the laminate film 41 of the stretched notch test piece 40, and parallel lines a and b were drawn at positions 25 mm away from the center line c on both ends. Further, on the surface of the galvanized steel sheet carrying the laminated film 41, a center line was also drawn at a portion corresponding to the center line c.
Next, the stretched notch test piece 40 was pulled from both ends (directions of arrows B and C in FIG. 4) by an Amsler tester, and the width (50 mm) of the central band (between the parallel lines a and b) was reduced to 60 mm. The film was stretched by 20% so as to obtain. Subsequently, the polypropylene film was cut along the center line c until the cutting edge of the cutter reached the steel sheet surface to form a score line.
Subsequently, as shown in FIG. 5 (schematic side view), the bending tester sets the stretched notch test piece 40 ′ after the tensile treatment on the laminate film 41 side to the front side and the galvanized steel sheet 42 to the back side. 5 and a column 55 (diameter = 2 mm) is placed at the center of the galvanized steel sheet 42 in the direction of arrow D in FIG. Notch bending was performed until the surfaces of the galvanized steel sheet 42 were completely adhered to each other. In the stretched notch test piece 40 ', the peeling state of the cut line formed on the laminate film 41 along the center line c was visually judged.
[0078]
(10) Heat-resistant stretch notch test
After leaving the stretched notch test piece of the preceding section (9) in a hot air oven at 150 ° C. for 1 hour, the peeling state of the film on the test piece was visually judged.
[0079]
(11) Criteria
The peel strength was expressed in units (N / 20 mm), and the evaluations of the Erichsen test and the stretch notch test were performed in the following five stages.
◎: Excellent,
◎ ⁻ : Slightly,
○: good,
△: Possible
×: Not possible.
Table 1 shows the results.
[0080]
[Table 1]

[0081]
【The invention's effect】
When the adhesive of the present invention is used, even when a hardly-adhesive resin film such as a polyolefin film is laminated on a steel sheet, it exhibits excellent heat resistance after laminating and ensures excellent adhesive strength even after a boiling water resistance test. Is done. In particular, as compared with the case where the acid-modified polyolefin resin is used alone, the heat resistance after processing is remarkably improved, and the adhesive strength after the boiling water resistance test can be extremely well secured.
Further, since the adhesive of the present invention is not a two-pack type but a one-pack type, it is advantageous in terms of workability, and has good temporal stability despite being a one-pack type.
Further, when the adhesive of the present invention is used, a pretreatment such as a corona discharge treatment or a primer treatment is not required particularly when a hardly-adhesive resin film, for example, a polyolefin film is laminated on a steel sheet.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a small piece for manufacturing a test piece for a peel test according to an example of the present specification.
FIG. 2 is a plan view of a test piece for a peel test according to an example of the present specification.
FIG. 3 is a schematic perspective view of a scratch test piece used for evaluating physical properties in Examples of the present specification.
FIG. 4 is a plan view of a stretched notch test piece used for evaluating physical properties in Examples of the present specification.
FIG. 5 is a schematic side view showing a state where the stretched notch test piece of FIG. 5 is bent by being attached to a bending tester.
[Explanation of symbols]
10 ... small pieces of test plate;
11, 21, 31, 41 ... polypropylene film;
12, 22, 32, 42 ... steel plate;
20: test piece; 11b, 21a: non-laminated part;
11a, 21b ... laminated part;
23a, 23b, 33a, 33b, 33c, 33d ... score lines;
12a, 22a: adhesive-uncoated strip portion; 22b: adhesive-coated portion;
30: scratch test specimen; 34: central head;
40 ... Stretch notch test piece; 55 ... Strut rod.

Claims (9)

(1) The hydroxyl-containing compound component (P) under the condition that the isocyanate group is excessive relative to the total hydroxyl groups of the hydroxyl-containing compound component (P) containing the polyester polyol (p1) and the hydroxyl-containing silicone compound (p2). Is reacted with a polyisocyanate compound (Q) to obtain a blocked isocyanate group-containing polyester polyurethane (A) obtained by blocking an unreacted isocyanate group of an isocyanate group-containing polyester polyurethane (A ′) with a blocking agent;
(2) an epoxy resin (B);
(3) An adhesive comprising an acid-modified polyolefin resin (C). The adhesive according to claim 1, wherein the epoxy resin (B) contains an epoxy phosphate resin (b1). The adhesive according to claim 2, further comprising a non-phosphate-modified epoxy resin (b2) as the epoxy resin (B). The adhesive according to claim 3, wherein the non-phosphoric acid-modified epoxy resin (b2) is an epoxy resin having no hydroxyl group. The adhesive according to any one of claims 1 to 4, wherein the hydroxyl-containing compound component (P) further contains a hydroxyl-containing epoxy resin (p3). The hydroxyl-containing compound component (P) is converted to a polyisocyanate under the condition that the isocyanate group is excessive with respect to the total hydroxyl groups of the hydroxyl-containing compound component (P) containing the polyester polyol (p1) and the hydroxyl-containing silicone compound (p2). Reacting with a compound (Q) to prepare an isocyanate group-containing polyester polyurethane (A ′), and blocking an unreacted isocyanate group in the isocyanate group-containing polyester polyurethane (A ′) with a blocking agent to form a blocked isocyanate group-containing polyester. Preparing an polyurethane (A), and subsequently mixing the blocked isocyanate group-containing polyester polyurethane (A), an epoxy resin (B), and an acid-modified polyolefin resin (C); Production method. The polyester according to claim 6, wherein the blocked isocyanate group-containing polyester polyurethane (A), the epoxy phosphate ester resin (b1), the non-phosphate-modified epoxy resin (b2), and the acid-modified polyolefin resin (C) are mixed. The manufacturing method as described. A blocked isocyanate group-containing polyester polyurethane (a1) is prepared using a hydroxyl group-containing compound component (P) further containing a hydroxyl group-containing epoxy resin (p3). The production method according to claim 6, wherein the acid ester resin (b1) and the acid-modified polyolefin resin (C) are mixed. A plastic film-laminated steel sheet obtained by laminating a plastic film and a steel sheet using the adhesive according to claim 1.

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