JP4386601B2 - Acrylic pressure-sensitive adhesive aqueous composition - Google Patents

Description

【００６３】
（式中、R²は１つ以上の芳香環を含む炭化水素基、M⁺はNa⁺、K⁺又NH₄ ⁺等の対イオンを表す）
【００６４】
上記一般式(2)におけるR²は、下記３種の構造式で示されるジスチリルの何れか又はそれらの混合物から誘導されたものであることが好ましい。
【００６５】
【化２】

【００６６】
上記のアニオン系界面活性剤におけるポリオキシエチレン鎖の長さ（ｎの値）としては、一般に４〜50の範囲であり、好ましく５〜45の範囲であるのがよい。これらアニオン系界面活性剤の具体例としては、例えば、ハイテノールNF-13、ハイテノールNF-17〔商品名；以上第一工業製薬(株)製〕、ニューコール707SF、ニューコール710SF、ニューコール714SF、ニューコール723SF、ニューコール740SF〔商品名；以上日本乳化剤(株)製〕等を挙げることができる。
【００６７】
また、これら乳化剤のアルキル基の水素の一部をフッ素で置換したものも使用可能である。
【００６８】
さらに本発明に用いられるアクリル系共重合体(A)の乳化共重合に際しては、必要に応じて、分子内にラジカル重合可能な不飽和基を有する、所謂「反応性乳化剤」を使用することができる。
【００６９】
このような反応性乳化剤としては、例えば、「エレミノールJS-2」、「エレミノールRS-30」〔以上、三洋化成工業(株)製〕、「アクアロンHS-10N」、「アクアロンHS-20N」〔以上、第一工業製薬(株)製〕、「アデカリアソープSE-10N」〔旭電化工業(株)製〕、「ラテムルS-120」、「ラテムルS-120A」、「ラテムルS-180」、「ラテムルS-180A」〔以上、花王(株)製〕等のアニオン系反応性乳化剤；例えば、「アクアロンRN-20」、「アクアロンRN-30」、「アクアロンRN-50」〔以上、第一工業製薬(株)製〕、「アデカリアソープNE-10」、「アデカリアソープNE-20」、「アデカリアソープNE-30」〔旭電化工業(株)製〕、「RMA-564」、「RMA-568」、「RMA-1114」〔以上、日本乳化剤(株)製〕等のノニオン系反応性乳化剤；などを挙げることができる。
【００７０】
さらにまた、最近、アクリル系共重合体の水性分散液中に汎用されているアルキルフェニル基を含む界面活性剤が、排水中に含まれて河川等に排出されたとき、それら界面活性剤の加水分解によって生じるアルキルフェノールが、それら河川及びそれが流入する海の中に生息する生物、特に魚貝類に取り込まれて、それら生物の内分泌機能（エンドクリン）破壊物質（所謂、環境ホルモン）として作用することが知られるようになった。このようなアルキルフェノールは、これら魚介類の摂取を通して、又は直接それら河川等の水を使用する上水道の水を通して、人の体内に入る危険性が高いことが指摘されている。
【００７１】
本発明においては、前記のノニオン系及びアニオン系界面活性剤の中から、上記のようなアルキルフェニル基を含まないものを選んで用いることにより上記の問題点を解消したアクリル系共重合体の水性分散液を得ることもできる。
【００７２】
このような界面活性剤としては、ノニオン系界面活性剤類として、ポリオキシエチレンアルキル（もしくはアルケニル）エーテル類、ソルビタン高級脂肪酸エステル類、ポリオキシエチレンソルビタン高級脂肪酸エステル類、ポリオキシエチレン高級脂肪酸エステル類、グリセリン高級脂肪酸エステル類、ポリオキシエチレン・ポリオキシプロピレン・ブロックコポリマーなどを使用することができ、またアニオン系界面活性剤類としては、高級脂肪酸塩類、アルキルアリールスルホン酸塩類、アルキル（もしくはアルケニル）硫酸エステル塩類、ポリオキシエチレンアルキル（もしくはアルケニル）エーテル硫酸エステル塩類、アルキル（もしくはアルケニル）スルホコハク酸エステル塩及びその誘導体類、前記一般式(2)のポリオキシエチレン多環フェニルエーテル型界面活性剤などを使用することができる。
【００７３】
これらの界面活性剤は適宜組合わせて使用するのがよく、その使用量としては一般に前記アクリル系共重合体(A)100重量部に対して0.3〜５重量部、好ましくは0.5〜３重量部、さらに好ましくは0.5〜２重量部程度の量で使用することができる。界面活性剤の使用量が該上限量以下であれば、形成される感圧接着剤層の耐水性が低下するなどの不都合が生じにくく、感圧接着剤層が金属蒸着面上に形成されている場合にも、蒸着抜け等の問題を起こしにくいので好ましい。一方、該使用量が該下限値以上であれば、アクリル系共重合体(A)の乳化重合に際して、凝集物の発生を最小限に抑えることができ、得られる水性感圧接着剤組成物の機械安定性が優れているので、該使用量範囲において適宜選択利用するのが好ましい。
【００７４】
本発明に用いられるアクリル系共重合体(A)の乳化重合に際しては、得られる共重合体の性能に悪影響を及ぼさない範囲において、前記のアニオン系及び／又はノニオン系乳化剤とともに水溶性保護コロイドを併用することもできる。
【００７５】
上記の水溶性保護コロイドとしては、例えば、部分ケン化ポリビニルアルコール、完全ケン化ポリビニルアルコール、変性ポリビニルアルコール等のポリビニルアルコール類；例えば、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、カルボキシメチルセルロース塩等のセルロース誘導体；及びグアガムなどの天然多糖類；などが挙げられ、これらは、単独でも複数種併用の態様でも利用できる。水溶性保護コロイドの使用量としては、前記単量体(a)〜(d)の合計100重量部当り０〜0.5重量部程度である。
【００７６】
更に乳化重合に際しては、通常、例えば、過硫酸ナトリウム、過硫酸カリウム、過硫酸アンモニウムなどの過硫酸塩類；t-ブチルヒドロペルオキシド、クメンヒドロペルオキシド、p-メンタンヒドロペルオキシドなどの有機過酸化物類；過酸化水素；などの重合開始剤が使用される。これら重合開始剤も一種もしくは複数種併用のいずれの態様でも利用できる。これらの重合開始剤は、前記単量体(a)〜(d)の合計100重量部に対して、0.1〜１重量部程度の量を用いるのが好ましい。
【００７７】
また乳化重合に際して、所望により、重合開始剤とともに還元剤を併用することができる。このような還元剤としては、例えば、アスコルビン酸、酒石酸、クエン酸、ブドウ糖、ホルムアルデヒドスルホキシラート金属塩等の還元性有機化合物；チオ硫酸ナトリウム、亜硫酸ナトリウム、重亜硫酸ナトリウム、メタ重亜硫酸ナトリウム等の還元性無機化合物；を例示できる。これら還元剤は、前記単量体(a)〜(d)の合計100重量部に対して、0.1〜１重量部程度の量を用いるのが好ましい。
【００７８】
更にまた、乳化重合に際しては連鎖移動剤を使用することができる。このような連鎖移動剤としては、例えば、n-ドデシルメルカプタン、t-ドデシルメルカプタン、n-ブチルメルカプタン、2-エチルヘキシルチオグリコレート、2-メルカプトエタノール、トリクロロブロモメタン等を挙げることができる。これら連鎖移動剤は、前記単量体(a)〜(d)の合計100重量部に対して0.1〜１重量部程度の量を用いるのが好ましい。
【００７９】
なお前記の水性媒体とは、水、並びに、水及び水と相溶性を有する有機溶媒からなる混合溶媒をいう。このような有機溶媒としては、例えば、メタノール、エタノール、n-プロピルアルコール、i-プロピルアルコール、n-ブチルアルコール、t-ブチルアルコール、エチレングリコール、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、エチレングリコールモノブチルエーテル、ジエチレングリコール、アセトン、メチルエチルケトン等を挙げることができる。本発明に用いるアクリル系共重合体の乳化共重合における水性媒体としては、水を主成分とするものを用いるのが好ましく、該水性媒体中に占める水溶性有機溶媒の含有量は、通常20重量％以下、好ましくは10重量％以下であるのがよい。
【００８０】
本発明に用いるアクリル系共重合体(A)の乳化共重合において好適に採用される共重合温度は、約40〜100℃、特には約50〜90℃である。
【００８１】
かくして得られたアクリル系共重合体(A)の水性分散液は、必要に応じて、アンモニア水等によってpＨ調節されることができる。このような分散液は、通常、固形分濃度30〜50重量％、粘度10〜3000mPa・s（BH型回転粘度計、25℃、20rpm；粘度測定条件以下同様）、pＨ２〜９程度であるのが好ましい。
【００８２】
本発明のアクリル系感圧接着剤水性組成物は、以上述べた水分散性アクリル系共重合体(A)と共に、水に溶解又は分散可能なポリエポキシ化合物(B)を含んでなるものである。
【００８３】
本発明において使用することができるポリエポキシ化合物(B)は、上記のように水に溶解又は分散可能なものであるが、アルキルフェニル系界面活性剤を含有していないものであることが好ましい。
【００８４】
このようなポリエポキシ化合物(B)としては、例えば、ポリオールポリグリシジルエーテル化合物、多酸ポリグリシジルエステル化合物等が好適に使用できる。
【００８５】
上記のポリオールとしては、例えば、エチレングリコール、ジエチレングリコール、ポリエチレングリコール、プロピレングリコール、ジプロピレングリコール、ポリプロピレングリコール、ネオペンチルグリコール、グリセロール、ジグリセロール、ポリグリセロール、トリメチロールエタン、トリメチロールプロパン、ペンタエリトリトール、ソルビトール、ソルビタンなどの脂肪族又は脂環族ポリオールを挙げることができ、上記多酸としては、例えばアジピン酸などを挙げることができる。
【００８６】
本発明において用いることのできるポリエポキシ化合物(B)のうち、ポリオールポリグリシジルエーテル化合物の具体例としては、例えば、エチレングリコールジグリシジルエーテル、ジエチレングリコールジグリシジルエーテル、ポリエチレングリコール（ｎ＝約４、９、13、22など）ジグリシジルエーテル、プロピレングリコールジグリシジルエーテル、ジプロピレングリコールジグリシジルエーテル、ポリプロピレングリコール（ｎ＝約３、11など）ジグリシジルエーテル、ネオペンチルグリコールジグリシジルエーテル、グリセロールジグリシジルエーテル、グリセロールトリグリシジルエーテル、ジグリセロールトリグリシジルエーテル、ポリグリセロール（ｎ＝約４、６など）ポリグリシジルエーテル、トリメチロールプロパンポリグリシジルエーテル、ペンタエリトリトールポリグリシジルエーテル、ソルビトールポリグリシジルエーテル、ソルビタンポリグリシジルエーテル等を挙げることができ、多酸ポリグリシジルエステル化合物の具体例としては、例えば、アジピン酸ジグリシジルエステル等を挙げることができる。
【００８７】
これらのポリエポキシ化合物(B)のうち特に好適なものは、エチレングリコールジグリシジルエーテル、ジエチレングリコールジグリシジルエーテル、グリセロールジグリシジルエーテル、グリセロールトリグリシジルエーテル、ジグリセロールトリグリシジルエーテル、ソルビトールポリグリシジルエーテル、ソルビタンポリグリシジルエーテルである。
【００８８】
このようなポリエポキシ化合物(B)の水性液としては、例えば「デナコール」の商品名でナガセ化成工業(株)より販売されている各種のエポキシ系架橋剤が好適に使用でき、例えば、デナコールEX-313、デナコールEX-314、デナコールEX-411、デナコールEX-512、デナコールEX-521、デナコールEX-611、デナコールEX-614として市販されているものが特に好適に使用できる。
【００８９】
ポリエポキシ化合物(B)は、前記アクリル系共重合体(A)100重量部に対して0.5〜10重量部用いることが必要であり、好ましくは0.5〜８重量部、さらに好ましくは１〜５重量部使用するのがよい。該使用量が該下限値未満と少なすぎては、感圧接着剤として必須の凝集力が不足しがちになり、また充分な基材密着性が発現しないので好ましくなく、また該上限値を超えて多すぎても所望の感圧接着剤物性をそれ以上高めることはなく、ポリエポキシ化合物が無駄になってしまい、その上被着体に対する接着力が低下するなどの不都合が生じることがあるので好ましくない。
【００９０】
本発明のアクリル系感圧接着剤水性組成物は、必要に応じて、さらに粘着付与樹脂を含有させることができる。本発明に使用可能な粘着付与樹脂としては、例えば、クマロン・インデン樹脂、テルペン樹脂、テルペン・フェノール樹脂、ロジン樹脂、p-t-ブチルフェノール・アセチレン樹脂、フェノール・ホルムアルデヒド樹脂、キシレン・ホルムアルデヒド樹脂、石油系炭化水素樹脂、水素添加炭化水素樹脂、テレピン系樹脂等を使用することができ、低温接着力及び曲面接着性のよさ等の観点から、ロジン樹脂、石油系炭化水素樹脂の使用が好ましい。また該粘着付与樹脂の軟化点は、一般に70〜180℃、好ましくは100〜180℃、特に好ましくは120〜170℃であることが好ましく、その重量平均分子量は、一般に5000以下、特には2000〜4000であることが好ましい。さらに本発明に用いることのできる粘着付与樹脂は、水性分散物であることが好ましい。
【００９１】
このような粘着付与樹脂としては、例えば、「スーパーエステルE-625A」、「スーパーエステルE-650」、スーパーエステルKE-788」〔以上荒川化学工業(株)製〕、「ハリエスターSK-130D」、「ハリエスターSK-508」、「LP-532 NF」〔以上ハリマ化成(株)製〕等のロジン樹脂；例えば、「QME-100」、「QME-125ps」、「QME-800」〔以上東邦化学工業(株)製〕等の石油系炭化水素樹脂；などの商品名で市販されているものを挙げることができ、これらの中、アルキルフェニル系界面活性剤を実質的に含有しない、「スーパーエステルKE-788」、「LP-532NF」、「QME-125ps」、「QME-800」が好適に使用される。
【００９２】
本発明において粘着付与樹脂を使用する場合には、その使用量は、前記アクリル系共重合体(A)100重量部に対して、一般に２〜45重量部、好ましくは４〜35重量部程度であるのがよい。
【００９３】
本発明のアクリル系感圧接着剤水性組成物はまた、所望の性能を損なわない限り、例えば、合成ゴム、天然ゴム、エチレン−酢酸ビニル共重合樹脂等の各種変性用樹脂を添加配合して使用することができる。これら各種変性用樹脂の添加量は、非極性ポリマーへの接着力と凝集力のバランスの観点から適宜選択でき、前記アクリル系共重合体の合計100重量部に対して、例えば０〜30重量部、好ましくは０〜20重量部のごとき添加量を例示できる。
【００９４】
さらに本発明の感圧接着剤組成物には、必要に応じて、可塑剤、湿潤剤、着色剤、無機質充填剤、安定剤、消泡剤、防腐剤、防黴剤等を添加配合して使用することもできる。
【００９５】
本発明のアクリル系感圧接着剤水性組成物は、製造の容易性などの観点から、前記のアクリル系共重合体(A)及びポリエポキシ化合物(B)、並びに必要に応じて用いられる前記粘着付与樹脂をそれぞれ水性液の形で混合し、さらに必要に応じて、これに湿潤剤、増粘剤等の上記配合物を添加・混合することにより調製することが好ましい。また、得られる感圧接着剤水性組成物中にもアルキルフェニル系界面活性剤を実質的に含有していないことが好ましいので、配合するポリエポキシ化合物、粘着付与樹脂、湿潤剤、増粘剤なども、アルキルフェニル系界面活性剤を実質的に含有していないことが好ましい。
【００９６】
かくして得られる本発明のアクリル系感圧接着剤水性組成物は：固形分濃度が、一般に30〜70重量％、好ましくは50〜70重量％；粘度が、一般に100〜20000 mPa・s、転写法に用いる場合には3000〜20000mPa・s；pHが、一般に３〜８程度であり、転写法に用いる場合には、pH４〜8.5が好適である。
【００９７】
本発明のアクリル系感圧接着剤水性組成物を用いて、感圧接着剤層を形成させる方法としては、紙又はプラスチックフイルム等の基材の上に該感圧接着剤組成物を、例えばロールコーター、ナイフコーターなどの一般に公知の手段を用いて直接塗布して乾燥させる直接法が採用でき、該感圧接着剤組成物を、シリコーン樹脂等で離型処理した紙又はフィルムなどからなる離型材上に同様の手段を用いて塗布し乾燥させて感圧接着剤層を形成させた後、該感圧接着剤層上に該基材を重ね加圧し、該基材上に該感圧接着剤層を転写する転写法も利用できるが、転写法を用いるのがより好ましい。
【００９８】
上記転写法では、離型材への塗工に際して、感圧接着剤組成物にハジキやヨリが生じるのを防ぐため、通常、各種の湿潤剤、増粘剤、粘性改良剤を用いて本発明の感圧接着剤組成物を増粘して使用する。
【００９９】
上記の湿潤剤としては、前記アニオン系界面活性剤中に例示したスルホコハク酸エステル塩型アニオン系界面活性剤がよく知られているが、本発明者等の研究によれば、この湿潤剤は、本発明の組成物により形成される感圧接着剤層の耐水性を低下させる傾向にあり、必ずしも良好なものではないことが判明した。
【０１００】
本発明者等のさらなる研究により明らかになったことは、本発明の感圧接着剤組成物には、得られる感圧接着剤層の耐水性のよさの観点から、ノニオン系の湿潤剤、具体的には下記構造式(3)を有するアセチレンジオール型ノニオン系湿潤剤を用いることが好ましいということである。
【０１０１】
【化３】

【０１０２】
（ここで、m1及びm2の合計は１〜40の範囲である）
【０１０３】
このようなアセチレンジオール型ノニオン系湿潤剤としては、例えば、「サーフィノール400シリーズ」の商品名でエアープロダクツジャパン(株)より販売されている各種の湿潤剤が好適に使用できる。アセチレンジオール型ノニオン系湿潤剤の使用量は、アクリル系感圧接着剤水性組成物100重量部に対して、例えば0.1〜1.5重量部、好ましくは0.2〜１重量部、さらに好ましくは0.3〜0.5重量部の範囲であるのがよい。該湿潤剤の使用量が該下限値以上であれば、該感圧接着剤組成物を離型材に塗工したときの塗面にハジキ、ピンホールの発生などがなく、良好な塗膜を形成し、且つ充分な耐水性を発現するので好ましく、また該上限値以下であれば、被着体に対する充分な接着力、基材との充分な密着性を発現するので好ましい。
【０１０４】
さらに前記の増粘剤、粘性改良剤としては、ポリアクリル酸ナトリウム、前記PVA類、前記セルロース誘導体、アルカリ性で増粘する水性分散型ポリ(メタ)アクリル酸系共重合体増粘剤等を例示することができる。これらの使用量は、所望の粘度、粘性に応じて適宜きめることができ、前記アクリル系感圧接着剤水性組成物の合計100重量部に対して固形分として０〜10重量部、好ましくは０〜５重量部の範囲である。
【０１０５】
本発明のアクリル系感圧接着剤水性組成物の使用において、好適に用いることのできる基材としては、例えば、ポリエチレンテレフタレート、ポリカーボネート、ポリスチレン、ポリ塩化ビニル、ポリアミド、熱可塑性ポリウレタン、石油系炭化水素樹脂、クマロン系樹脂、ロジン誘導体、天然樹脂、天然アスファルトなどの軟化点60℃以上の熱可塑性樹脂フィルムもしくはシート；例えば、普通紙、上質紙、アート紙、キャスト紙、感熱記録紙、厚紙、段ボールなどの紙類；例えば、フェノール樹脂、メラミン樹脂、ユリア樹脂、エポキシ樹脂、不飽和ポリエステル樹脂、ウレタン樹脂などの熱硬化性樹脂シート；例えば、鉄、鋼、アルミニウム、ニッケル、クロム、コバルト、ステンレス鋼、亜鉛処理鋼板、銅鍍金鋼板、銅、黄銅などの金属もしくは金属合金の箔；例えば、ガラス、セラミックなどの無機質シートなどを例示することができる。ポリエチレンテレフタレート（PET）、二軸延伸ポリプロピレン（OPP）、無延伸ポリプロピレン（CPP）の使用が好ましく、特にアルミニウムなどの金属蒸着フィルムの蒸着面への使用が好ましい。これら基材の厚さは、一般に約10〜2000μm 、好ましくは約20〜1000μm程度であるのが好ましい。
【０１０６】
【実施例】
以下に実施例、比較例、参考例によって本発明をさらに具体的に説明するが、本発明はこれら実施例により限定されるものではない。
なお、試験片の作製、並びに各種物性試験は以下の試験方法に従った。
【０１０７】
(1) 試験用感圧接着シートの作製
シリコーン系離型剤で表面処理された離型紙〔ENクリーム-2；王子タック販売(株)製〕上に、乾燥後の塗工量が20g/m²となるように感圧接着剤組成物をドクターブレードにより塗布し、110℃で60秒間熱風循環式乾燥機にて乾燥して感圧接着剤層を形成した後、該感圧接着剤層面に基材（アルミ蒸着OPP又はアルミ蒸着PET）のアルミ蒸着面をハンドローラーで貼り合わせ、これを引き続いてハンドプレスで一昼夜プレスした後、40℃恒温槽で３日間養生させたものを試験用感圧接着シートとした。
【０１０８】
(2) PET 永久接着力の測定
PETフィルム〔E5001；東洋紡績(株)製〕を両面テープ〔No.501F；日東電工(株)製〕で平滑なポリエチレン（PE）板（２×125×150mm）に貼り合わせて24時間以上放置したものを試験板（被着体）として用い、これに、前(1)項で作製した試験用感圧接着シートより切り出した試験片（25mm×150mm）をJIS Z 0237の方法に従って圧着し、次いで23℃、65％RHの雰囲気下で24時間以上放置したものを、23℃、65％RHの雰囲気下、JIS Z 0237に準拠し、剥離速度300 mm/分の条件で180゜剥離試験を行って剥離強度(N/25mm)を測定した。剥離強度としては、例えば８N/25mm以上、特には10N/25mm以上であることが好ましい。
【０１０９】
また剥離面の破壊形態は、測定後、試験板へ転着している感圧接着剤の割合を目視で観察して、下記の基準に従い判定した。
【０１１０】
〔評価基準〕
○：粘着剤が試験板に転着してしない。
△：試験板へ試験片の50％未満の粘着剤が転着している。
×：試験板へ試験片の50％以上の粘着剤が転着している。
【０１１１】
(3) 耐水接着力の測定
前(2)項において、試験片を貼り合わせて得た試験板を24時間以上放置した後、さらに40℃の水中に48時間以上浸漬し、測定間際に水中より取り出し、余った水分を拭き取ってから測定する以外は前(2)項と同様にして180゜剥離にて耐水接着力(N/25mm)を測定した。耐水接着力としては、例えば５N/25mm以上、特には７N/25mm以上であることが好ましい。
【０１１２】
また透明性は、接着力測定後の粘着シートの粘着剤面の透明性を目視評価により判定した。
【０１１３】
〔評価基準〕
○：粘着剤面の透明性良好（粘着剤面が白化していない）。
△：粘着剤面がやや白化している。
×：粘着剤面が完全に白化している。
【０１１４】
(4) エッジリフトの測定
130mmφのPE棒を酢酸エチルで脱脂して被着体とし、これに、前(1)項で作製した試験用感圧接着シートより切り出した試験片（16mm×25mm）の離型紙を剥がして上記被着体に手で貼り合わせ、圧着した後23℃×65％RHで24時間放置した。24時間経過後、試験用感圧接着シートの被着体からの跳ね返りによる剥離の状態を両側の剥離長さの合計より判定した。
【０１１５】
〔評価基準〕
○：０〜２mm未満
△：２〜10mm未満
×：10〜25mm
【０１１６】
(5) 基材密着力の測定
アルミニウム板（厚さ１mm）の表面を耐水研磨紙#280で研磨し、水洗後酢酸エチルで脱脂し、これにエポキシ系接着剤〔#16051；コニシ(株)製〕を均一に薄く塗布した。前(1)項で作製した試験用感圧接着シートより切り出した試験片（25mm×150mm）の離型紙を剥がし、その感圧接着シートの感圧接着剤面を上記エポキシ系接着剤面に貼り合わせ、スキージで圧着させて一昼夜放置したものを試料とした。
【０１１７】
上記試料を、剥離速度を500mm/分する以外は前(2)項と同様の条件で180゜剥離にて接着力(N/25mm)を測定し、基材密着力とした。基材密着力としては、例えば７N/25mm以上、特には14N/25mm以上であることが好ましい。
【０１１８】
(6) 被着体への糊残り
台所用合成洗剤〔ファミリーコンパクト300Ml；花王(株)製〕のボトルから内容液（洗剤液）を抜き取り、表面のラベルを丁寧に手で剥がし、水洗後、エタノールでボトル表面を脱脂して、これを被着体とする。この被着体に、前(1)項で作製した試験用感圧接着シートより切り出した試験片（105mm×54mm角）から離型紙を剥がし、手で丁寧に貼り合わせて圧着し24時間放置したものを試料とした。
【０１１９】
次に上記で抜き取った洗剤液を大きめの容器に入れて、上記試料をこの洗剤液中に完全に浸漬し、アルミホイルなどで蓋をして40℃恒温槽内で48時間放置した。48時間放置後、恒温槽より容器を取り出し、室温で放冷した後、洗剤液中より試料を取り出し、試料を水洗後、余った水分をティッシュペーパーなどで拭き取り、被着体であるボトルより、手で感圧接着シートを高速又は低速でそれぞれ引き剥がしたときの被着体への感圧接着剤の転着状態を次の基準に従って判定した。
【０１２０】
〔判定基準〕
○：高速及び低速剥離の何れでも感圧接着剤が被着体に転着しない。
△：高速剥離では転着するが、低速剥離では転着しない。
×：高速及び低速剥離の何れでも感圧接着剤が被着体に転着する。
【０１２１】
(7) 蒸着抜け
前(1)項で作製した試験用感圧接着シートより切り出した試験片（50mm×150mm）の剥離紙を剥がし、75℃×95％RHに調整した恒温恒湿機内に７日間放置後の基材のアルミ蒸着の抜けを目視評価し、下記の基準により判定した。
【０１２２】
〔判定基準〕
○：基材のアルミ蒸着の抜けなし。
△：基材のアルミ蒸着が50％未満抜ける。
×：基材のアルミ蒸着が50％以上抜ける。
【０１２３】
(8) 凝集力
前(1)項で作製した試験用感圧接着シートより切り出した試験片（25mm×150mm）を用い、その保持力を測定する。保持力測定方法は、JIS Z 0237に準拠し、荷重1,000g、圧着回数５往復、測定温度60℃、測定時間1,000分での落下時間を測定し、下記の評価基準に従い、凝集力を判定した。
【０１２４】
〔評価基準〕
○：落下時間 1,000〜800分
△：落下時間 800〜400分
×：落下時間 400〜0分
【０１２５】
＜水分散型アクリル系共重合体の水性分散液の作製＞
【０１２６】
製造例１
攪拌機、温度計、還流冷却器、窒素導入管及び単量体プレミックス供給ポンプを備えた反応器中に、脱イオン水50重量部と、界面活性剤として「ハイテノールNF-17」〔ポリオキシエチレン（ｎ＝17.5）ジスチリルフェニルエーテル硫酸エステルアンモニウム塩型アニオン系界面活性剤（有効成分濃度95重量％）；第一工業製薬(株)製〕（NF-17）0.1重量部を仕込み、温度調節装置付きウォーターバスを用い、内温を70℃に昇温させた。
【０１２７】
一方、別の容器に、脱イオン水28.1重量部、界面活性剤「NF-17」0.9重量部、単量体ブチルアクリレート（BA）76.8重量部、メチルメタクリレート（MMA）21.6重量部、アクリル酸（AA）1.5重量部及び、2-メタクリロイルオキシエチルジヒドロゲンホスフェート〔「ホスマーＭ」；ユニケミカル(株)製〕0.1重量部、並びに連鎖移動剤n-ドデシルメルカプタン（n-DM）0.3重量部を撹拌して単量体プレミックスを作成した。
【０１２８】
次いで反応器の空間部を窒素で置換しながら内容物を撹拌し、９重量％「パーブチルH」（t-ブチルヒドロペルオキシド）0.74重量部と、20重量％「ロンガリット」（ナトリウムホルムアルデヒドスルホキシラート）0.333重量部を投入した。
【０１２９】
次に上記単量体プレミックスを、1.4％「パーブチルH」10.55重量部及び1.4重量％「ロンガリット」10.55重量部と共に３時間逐次滴下して乳化重合行った。単量体プレミックス等の逐次滴下終了後、同温度で約１時間撹拌を継続した後、反応混合物を30℃に冷却し、アンモニア水でpH調整して、水分散型アクリル系共重合体の水性分散液を作製した。得られた水性分散液は、固形分約48重量％、pH 7.2、粘度700mPa・s（25℃、BH型回転粘度計20rpm）、分散粒子の平均粒子径約116nmであり、共重合体のガラス転移点（Tg）は約−33℃、重量平均分子量（Mw）は約20万であった。
【０１３０】
製造例２
製造例１において、表１に示すとおりAAを用いず、AAの変化の分はMMAを加える以外は製造例１と同様にしてアクリル系共重合体の水性分散液を得た。なお、その乳化重合に際してかなり多量の凝集物が発生したため、辛うじて濾過できた分のみを用いた。共重合に用いた単量体組成、連鎖移動剤及び界面活性剤の使用量を表１に、得られたアクリル系共重合体水性分散液の固形分、pH、粘度及び分散粒子の平均粒子などの特性値、並びにアクリル系共重合体のガラス転移点（Tg）、重量平均分子量（Mw）などの特性値を表２示す。
【０１３１】
製造例３〜４
製造例１において、表１に示すとおり「ホスマーM」の使用量を0.5重量％に変え、又はこれを用いず、「ホスマーM」の変化の分はBAを加減する以外は製造例１と同様にしてアクリル系共重合体の水性分散液を得た。共重合に用いた単量体組成、連鎖移動剤及び界面活性剤の使用量を表１に、得られたアクリル系共重合体水性分散液の特性値及びアクリル系共重合体の特性値を表２示す。
【０１３２】
製造例５〜７
製造例１において、表１に示すとおり、BAの代わりに2-エチルヘキシルアクリレート（EHA）を用い、又はBAとMMAの使用割合を変えもしくはMMAを使用しないなどによりアクリル系共重合体のガラス転移点（Tg）を変える以外は製造例１と同様にしてアクリル系共重合体の水性分散液を得た。共重合に用いた単量体組成、連鎖移動剤及び界面活性剤の使用量を表１に、得られたアクリル系共重合体水性分散液の特性値及びアクリル系共重合体の特性値を表２示す。
【０１３３】
製造例８〜10
製造例１において、表１に示すとおり連鎖移動剤（n-DM）の使用量を変え又はこれを用いないことによりアクリル系共重合体の重量平均分子量（Mw）を変える以外は製造例１と同様にしてアクリル系共重合体の水性分散液を得た。共重合に用いた単量体組成、連鎖移動剤及び界面活性剤の使用量を表１に、得られたアクリル系共重合体水性分散液の特性値及びアクリル系共重合体の特性値を表２示す。
【０１３４】
製造例11
製造例１において、最初に反応器中に仕込む界面活性剤「NF-17」の量を0.01重量部とし、その分単量体プレミックス作成用の界面活性剤「NF-17」の量を増やして0.99重量部とすることによりアクリル系共重合体の分散粒子の平均粒子径を変える以外は製造例１と同様にしてアクリル系共重合体の水性分散液を得た。共重合に用いた単量体組成、連鎖移動剤及び界面活性剤の使用量、並びに得られたアクリル系共重合体水性分散液の特性値及びアクリル系共重合体の特性値を表１示す。
【０１３５】
【表１】

【０１３６】
【表２】

【０１３７】
＜水性アクリル系感圧接着剤組成物の作製＞
【０１３８】
実施例１
製造例１で得られたアクリル系共重合体水性分散液208重量部（アクリル系共重合体として約100重量部）に対して、水溶性ポリエポキシ化合物〔「デナコールEX-512」；グリセロールポリグリセロール型ポリエポキシ化合物、エポキシ当量173；ナガセ化成工業(株)製〕（EX-512）3.6重量部、アセチレンジオール系湿潤剤〔「サーフィノール440」；エアープロダクツジャパン(株)製〕0.624重量部、及びポリエーテル系増粘剤〔「アデカノールUH-550」；旭電化工業(株)製〕を脱イオン水で2.5倍に希釈した水溶液4.16重量部を加え、ホモミキサーで撹拌して、固形分46.2重量％、pH7.2、粘度約12,600mPa・s（25℃、BM型回転粘度計60rpm）のアクリル系感圧接着剤水性組成物を作製した。
この組成物を用いて、前記(1)の方法に従い試験用の感圧接着シートを作成し、前記試験方法(2)〜(7)に従って感圧接着シートの物性測定を行った。感圧接着剤組成物の配合組成、並びにそのpH、粘度及び固形分などの特性値を表３に、感圧接着シートの諸物性を表４に示す。
【０１３９】
実施例２及び比較例１
実施例１において、「EX-512」を3.6重量部用いる代わりに、0.5重量部用い又はこれを用いない以外は実施例１と同様にしてアクリル系感圧接着剤水性組成物を作製した。得られた感圧接着剤組成物の配合組成及び特性値を表３に、感圧接着シートの諸物性を表４に示す。
【０１４０】
実施例３
実施例１において、「EX-512」を3.6重量部用いる代わりに「EX-411」を4.8重量部用いる以外は実施例１と同様にしてアクリル系感圧接着剤水性組成物を作製した。得られた感圧接着剤組成物の配合組成及び特性値を表３に、感圧接着シートの諸物性を表４に示す。
【０１４１】
実施例４〜７及び比較例２〜７
実施例１において、製造例１のアクリル系共重合体水性分散液を208重量部用いる代わりに、表３に示すように、製造例２〜11のアクリル系共重合体水性分散液を、それぞれのアクリル系共重合体が約100重量部となるように、それぞれの固形分に応じて使用する以外は実施例１と同様にしてアクリル系感圧接着剤水性組成物を作製した。得られた感圧接着剤組成物の配合組成及び特性値を表３に、感圧接着シートの諸物性を表４に示す。
【０１４２】
【表３】

【０１４３】
【表４】

【０１４４】
【発明の効果】
本発明のアクリル系感圧接着剤水性組成物は、分子中にカルボキシル基及び酸性リン酸エステル基を含有し、特定のガラス転移点（Tg）及び重量平均分子量（Mw）を有する水分散性アクリル系共重合体であって、その分散粒子が200nm以下の平均粒子径を有するアクリル系共重合体(A)に対して、水に溶解又は分散可能なポリエポキシ化合物(B)を特定量範囲含んでなるものである。
【０１４５】
上記のように構成された本発明のアクリル系感圧接着剤水性組成物は、各種のポリマーフィルム、特に金属蒸着フィルム等の基材に対して優れた基材密着性を示す高度の透明性を有する感圧接着剤層を形成することができ、得られた感圧接着剤層は、感圧接着剤として必須の各種被着体に対する優れた接着力及び凝集力を維持しつつ、曲面被着体に対する耐「エッジリフト」性、耐水性、特に金属蒸着フィルムを基材とするときには蒸着抜け防止性、剥離後における被着体への糊残りのなさなど、感圧接着剤として卓越した性能を発揮する。[0001]
BACKGROUND OF THE INVENTION
The present invention is a pressure-sensitive adhesive sheet or film based on various polymer films, in particular, a metal vapor-deposited film, and has excellent adhesive force and cohesive force on various adherends or The acrylic pressure-sensitive adhesive aqueous composition that can be suitably used for the production of a film, specifically, contains a carboxyl group and an acidic phosphate group in the molecule, and has a specific glass transition point (Tg) and A water-dispersible acrylic copolymer having a weight average molecular weight (Mw), and the dispersed particles can be dissolved or dispersed in water with respect to the acrylic copolymer (A) having an average particle diameter of 200 nm or less. The present invention relates to an aqueous acrylic pressure-sensitive adhesive composition comprising a specific amount range of such a polyepoxy compound (B).
[0002]
[Prior art]
Applications of pressure-sensitive adhesives are wide-ranging, such as tapes, sheets, labels, stickers, wallpaper, etc., and the materials of adherends are wide-ranging such as plastic, metal, glass, ceramics, paper, cloth, wood, and fresh foods. Over.
[0003]
Conventionally, natural rubber, synthetic rubber, ethylene-vinyl acetate copolymer, acrylic copolymer, etc. are used as the main raw materials for pressure sensitive adhesives in a form dissolved in an organic solvent or dispersed in water. Has been. Among these, a pressure-sensitive adhesive mainly composed of a water-dispersed acrylic copolymer, that is, a water-dispersed acrylic copolymer does not contain an organic solvent, and does not cause fire or environmental health problems. So it has become increasingly popular.
[0004]
However, conventional pressure-sensitive adhesives composed of water-dispersed acrylic copolymers inevitably use a hydrophilic surfactant or protective colloid to disperse the polymer in water. Compared to solvent-type pressure-sensitive adhesives, the pressure-sensitive adhesive layers that are formed have difficulties in water resistance and transparency, especially when a transparent material such as a plastic film is used as the substrate. If the pressure-sensitive adhesive layer absorbs rain or moisture in the atmosphere to cause whitening, and if a pressure-sensitive adhesive layer is formed on the metal deposition surface such as aluminum, this moisture causes the metal to Oxidized and pierced, often causing so-called “deposition loss”, often having a significant adverse effect on the sharpness of the printed matter on the film, and adhesion of the pressure sensitive adhesive layer to the film substrate Is not enough Hard, it was quite poor, especially adhesion against the metal deposition surface.
[0005]
In order to improve the water resistance of a pressure-sensitive adhesive composed of such a water-dispersed acrylic copolymer, a so-called reactive surfactant having a surface-active ability and copolymerization with an acrylic monomer is used. Several proposals used are known. For example, JP-A-9-143444 discloses a water-dispersed acrylic pressure-sensitive adhesive using a nonionic reactive surfactant. However, this proposed water-dispersed acrylic pressure-sensitive adhesive tends to generate a large amount of agglomerates during its production, tends to have a large particle size, and is totally insufficient in terms of water resistance and substrate adhesion. It was a thing.
[0006]
In addition, publications such as JP-A-7-26229 and JP-A-7-278233 disclose water-dispersed acrylic pressure-sensitive adhesives using an anionic reactive surfactant. Although these pressure-sensitive adhesives certainly show a certain improvement in water whitening resistance, the pressure-sensitive adhesive layers obtained from these adhesives have an anionic reactive surfactant that changes over time due to heat, ultraviolet rays, etc. There were problems such as causing discoloration in response to changes.
[0007]
Furthermore, a water-dispersed acrylic pressure-sensitive adhesive containing a phosphate group in the molecule is also known. For example, JP-A-53-65331 discloses a carboxyl group together with an acrylic ester as a main component. A water-dispersed acrylic pressure-sensitive adhesive for a surface protective sheet, which is obtained by copolymerizing a group-containing monomer, a hydroxyl group-containing monomer, and an acid-type phosphate group-containing monomer, is disclosed. In this proposal, this pressure sensitive adhesive is applied onto a 0.1 mm thick polyvinyl chloride film and heated at 150 ° C. for 2 minutes to form carboxyl groups and hydroxyl groups together with the catalytic action of phosphate ester groups. It is described that a crosslink is formed by an esterification reaction.
[0008]
However, the water-dispersed acrylic pressure-sensitive adhesive proposed in JP-A-53-65331 uses a large amount of surfactant and is not sufficient in terms of water whitening and loss of vapor deposition. Since a high temperature is used, it has been found that problems such as deformation occur depending on the plastic film of the substrate.
[0009]
Furthermore, JP-A-2000-186259 discloses a monomer containing a (meth) acrylic acid ester, an ethylenically unsaturated carboxylic acid and a phosphoric acid ester compound having one or more ethylenically unsaturated groups or a salt thereof. Water containing a reducing agent contained in an aqueous acrylic copolymer dispersion having a fine particle diameter (around 120 nm in the examples) obtained by emulsion copolymerization in the presence of an anionic reactive surfactant Dispersed acrylic pressure sensitive adhesives are disclosed.
[0010]
However, in the proposal of the above Japanese Patent Laid-Open No. 2000-186259, the transparency, water whitening resistance, yellowing resistance with time, etc. are described in detail, but there is no description about “deposition loss” and its improvement. There is no difference. Further, in the specific embodiment disclosed, since there is no formation of cross-linking such as by using a cross-linking agent together, the cohesive force of the generally obtained pressure-sensitive adhesive layer has to be insufficient. Moreover, it may not be impossible to improve cohesion by introducing internal crosslinking into the copolymer by using a phosphoric ester compound having two or more ethylenically unsaturated groups. The adhesion to the substrate will be reduced.
[0011]
[Problems to be solved by the invention]
In order to solve the problems of the conventional pressure-sensitive adhesives, the present inventors have conducted improvement studies on water-based acrylic pressure-sensitive adhesives. As a result, for example, a copolymer derived from butyl acrylate is used as the main chain, and the side chain contains a carboxyl group and an acidic phosphate group, and has a glass transition point (Tg) of −25 ° C. or less and a weight average molecular weight ( Mw) A water-dispersible acrylic copolymer having 100,000 to 600,000, wherein the dispersed particles have an average particle diameter of 200 nm or less, and 0.5 to 10 weights of water-soluble polyepoxy compound. By blending in part, while maintaining the adhesive strength and cohesive strength to adherends essential as a pressure sensitive adhesive, all of the above-mentioned problems such as transparency, water whitening resistance, deposition loss prevention properties, substrate adhesion, etc. We have found that it can be solved, and further researched to complete the present invention.
[0012]
[Means for Solving the Problems]
According to the present invention, the following (A) and (B),
[0013]
(A) The molecule contains a carboxyl group and an acidic phosphate group, has a glass transition point (Tg) of −25 ° C. or less, has substantially no gel content before crosslinking, and has a weight average molecular weight (Mw ) Is a water dispersible acrylic copolymer in the range of 100,000 to 600,000, 100 parts by weight of the acrylic copolymer having an average particle diameter of 200 nm or less, and
[0014]
(B) 0.5-10 parts by weight of a polyepoxy compound that can be dissolved or dispersed in water,
An acrylic pressure-sensitive adhesive aqueous composition is provided.
[0015]
Hereinafter, the present invention will be described in more detail.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The water-dispersible acrylic copolymer (A) that can be used in the acrylic pressure-sensitive adhesive aqueous composition of the present invention is water or an acrylic dispersed in fine particles in an aqueous medium containing water as a main component. A copolymer comprising a carboxyl group and an acidic phosphate group in the molecule of the acrylic copolymer. Here, the acidic phosphate group means a phosphate group containing at least one active hydrogen atom or a salt thereof.
[0017]
Furthermore, the acrylic copolymer (A) used in the present invention has a glass transition point (Tg) of −25 ° C. or lower, preferably −50 to −25 ° C., more preferably −30 to −40 ° C. is required. If the glass transition point (Tg) exceeds the upper limit and is too high, the resulting pressure-sensitive adhesive layer becomes too hard, and it is difficult to obtain sufficient adhesion to the adherend, which is not preferable.
[0018]
In the present invention, the glass transition point (Tg) of the acrylic (co) polymer is a value measured and determined by the following method.
[0019]
Glass transition point ( Tg ):
About 10 mg of an aqueous dispersion of acrylic copolymer was weighed in a cylindrical cell made of aluminum foil with a thickness of about 0.05 mm and an inner diameter of about 5 mm and a depth of about 5 mm, and dried at 100 ° C. for 2 hours. A measurement sample is used. Using an SSC-5000 type differential scanning calorimeter manufactured by Seiko Denshi Kogyo Co., Ltd., the temperature is measured from −150 ° C. at a heating rate of 10 ° C./min.
[0020]
In the measurement of the above glass transition point (Tg), an acrylic pressure-sensitive adhesive aqueous composition in which an acrylic copolymer is dispersed in an aqueous medium together with a polyepoxy compound, a tackifier resin, a surfactant and the like described later. When an additive such as a pigment or an inorganic filler is further blended, for example, the composition or the blend is appropriately diluted with ion-exchanged water to reduce the viscosity (for example, about 50 mPa S or less), and then adjusting the rotation speed and rotation time to separate these additives by centrifuging to obtain an aqueous dispersion of an acrylic copolymer and a tackifier used for measuring the glass transition point. Can be separated and collected. The reason why such separation is possible is that the specific gravity of the acrylic copolymer used in the present invention is very close to 1, compared with other additives used in tackifiers and pressure sensitive adhesive compositions. Because it is light.
[0021]
Furthermore, the acrylic copolymer (A) used in the present invention has substantially no gel content before crosslinking, and its weight average molecular weight (Mw) is 100,000 to 600,000, preferably 15 It is necessary to be in the range of 10,000 to 400,000, more preferably 150,000 to 300,000. If the weight average molecular weight (Mw) is too low as less than the lower limit value, the cohesive force of the pressure-sensitive adhesive layer formed from the resulting acrylic pressure-sensitive adhesive aqueous composition tends to be insufficient, which is not preferable. . On the other hand, if it exceeds the upper limit and is too high, the adhesion to a substrate such as a film tends to be insufficient, which is not preferable. Incidentally, “substantially no gel content before crosslinking” means that the acrylic copolymer (A) before being crosslinked by the epoxy compound (B) described later is in tetrahydrofuran at a concentration of about 0.2 g / 100 ml. This means that the insoluble content when dissolved is generally 2.0% by weight or less, preferably 0.5% by weight or less, based on 100% by weight of the acrylic copolymer used for dissolution.
[0022]
The dispersed particles in the aqueous medium of the acrylic copolymer used in the present invention are required to have an average particle size of 200 nm or less, preferably 150 nm or less, particularly preferably 125 nm or less. If the average particle size of the dispersed particles exceeds the upper limit, the pressure-sensitive adhesive layer formed from the resulting acrylic pressure-sensitive adhesive aqueous composition has an adhesion to a substrate such as a plastic film. In some cases, the water resistance of the pressure-sensitive adhesive layer tends to decrease, and when the pressure-sensitive adhesive layer is formed on the metal vapor-deposited surface, problems such as omission of vapor deposition occur. Since it may occur, it is not preferable.
[0023]
In the present specification, the average particle diameter of the dispersed particles is a value measured by a laser diffraction particle size distribution measuring device, and specifically measured using “Mastersizer 2000” (manufactured by Sysmex Corporation). The weight average diameter.
[0024]
The acrylic copolymer (A) used in the present invention is not necessarily limited, but is preferably a copolymer obtained by copolymerizing 50% by weight or more of (meth) acrylic acid ester.
[0025]
Specifically, the acrylic copolymer (A) suitably used in the present invention includes the following monomers (a) to (d),
[0026]
(a) Acrylic acid ester represented by the following general formula (1) and having a glass transition point of the homopolymer of −50 ° C. or less (hereinafter referred to as main monomer (a) or simply monomer (a) 54-99.4% by weight,
[0027]
CH₂= CH-COOR¹           (1)
(Where R¹Represents a linear or branched alkyl group having 4 to 12 carbon atoms)
[0028]
(b) an α, β-unsaturated mono- or di-carboxylic acid having 3 to 5 carbon atoms (hereinafter sometimes referred to as unsaturated carboxylic acid (b) or simply monomer (b)) 0.5 to 3% by weight ,
[0029]
(c) Monomer containing one radical polymerizable unsaturated group and acidic phosphate group in the molecule [hereinafter sometimes referred to as phosphate ester monomer (c) or simply monomer (c) ] 0.01 to 3% by weight, and
[0030]
(d) a comonomer other than the monomers (a) to (c) that can be copolymerized with the monomers (a) to (c) (hereinafter simply referred to as a comonomer (d)) 40% by weight or less,
[0031]
[However, the total amount of monomers (a) to (d) used is 100% by weight.]
Is preferably obtained by emulsion copolymerization.
[0032]
The main monomer (a) is an acrylate monomer represented by the general formula (1), and the homopolymer has a glass transition point of −50 ° C. or lower.
[0033]
Specific examples of such acrylic esters include n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, i-nonyl acrylate, and the like. The use of n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, i-nonyl acrylate, and the like is particularly preferable.
[0034]
As used herein, “glass transition point (Tg) of homopolymer” includes the monomer glass described in LE Nielsen, translated by Nojiharu Onoki, “Mechanical Properties of Polymers” on pages 11-35. A transition point is applied.
[0035]
The amount of the main monomer (a) used is the total monomer component forming the acrylic copolymer used in the present invention, and a total of 100% by weight of the monomers (a) to (d). The content is preferably in the range of 54 to 99.4% by weight, more preferably 65.5 to 89.2% by weight, and particularly preferably 72 to 88.9% by weight. If the amount of the monomer (a) used is equal to or greater than the lower limit amount, the adhesive force, tack and cohesive force of the pressure-sensitive adhesive layer to be formed are preferably balanced and, on the other hand, not more than the upper limit amount. If present, it is preferable because inconveniences such as insufficient cohesive force are unlikely to occur.
[0036]
The aqueous acrylic copolymer of the present invention is preferably obtained by emulsion copolymerization using the unsaturated carboxylic acid (b) as an essential component together with the main monomer (a).
[0037]
Specific examples of such unsaturated carboxylic acid (b) include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and citraconic acid. Among these, use of acrylic acid or methacrylic acid is more preferable.
[0038]
The amount of the unsaturated carboxylic acid (b) used is preferably within a range of 0.5 to 3% by weight, more preferably 0.7 to 3%, based on a total of 100% by weight of the monomers (a) to (d). It should be 2.5% by weight, particularly preferably 1-2% by weight. If the amount of unsaturated carboxylic acid (b) used is less than or equal to the upper limit, problems such as reduced tack and water resistance of the formed pressure-sensitive adhesive layer are unlikely to occur, and the pressure-sensitive adhesive layer is metal-deposited. Even when it is formed on the surface, it is preferable because problems such as vapor deposition are unlikely to occur. On the other hand, if the amount used is equal to or greater than the lower limit, the generation of aggregates can be minimized during the emulsion polymerization of the acrylic copolymer (A), and the resulting aqueous pressure-sensitive adhesive composition Since the mechanical stability and the adhesive strength of the resulting pressure-sensitive adhesive layer are excellent and inconveniences such as insufficient cohesive force are unlikely to occur, it is preferable to appropriately select and use within the usage amount range.
[0039]
The aqueous acrylic copolymer of the present invention is obtained by emulsion copolymerization using the phosphate monomer (c) as an essential component together with the main monomer (a) and the unsaturated carboxylic acid (b). It is preferable that
[0040]
Specific examples of such phosphate ester monomer (c) include mono (2-acryloyloxyethyl) dihydrogen phosphate, mono (2-methacryloyloxyethyl) dihydrogen phosphate, mono (2-acryloyloxypropyl) Dihydrogen phosphate, mono (2-methacryloyloxypropyl) dihydrogen phosphate, mono (3-acryloyloxypropyl) dihydrogen phosphate, mono (3-methacryloyloxyethyl) dihydrogen phosphate, monoallyl dihydrogen phosphate, etc. it can.
[0041]
The amount of the phosphoric acid ester monomer (c) used is preferably within a range of 0.01 to 3% by weight, more preferably with respect to 100% by weight of the monomers (a) to (d). Is 0.03 to 2% by weight, particularly preferably 0.05 to 1% by weight. If the amount of the monomer (c) used is less than or equal to the upper limit, it is preferable because sufficient adhesive force is exerted on the adherend. On the other hand, if the amount used is equal to or more than the lower limit value, it is preferable because excellent cohesive force essential as a pressure-sensitive adhesive can be obtained and sufficient adhesion to a substrate is exhibited.
[0042]
The acrylic copolymer (A) suitably used in the present invention, together with the main monomer (a), unsaturated carboxylic acid (b) and phosphate ester monomer (c) as essential components, The above-mentioned comonomer (d) can be copolymerized as necessary.
[0043]
Examples of such a comonomer (d) include acrylic esters other than the main monomer (a), and specific examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, Examples include i-propyl acrylate, i-butyl acrylate, t-butyl acrylate, stearyl acrylate, oleyl acrylate, cyclohexyl acrylate, and benzyl acrylate (preferably methyl acrylate).
[0044]
Examples of the comonomer (d) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, i -Methacrylic acid esters such as decyl methacrylate, lauryl methacrylate, tridecyl methacrylate, cetyl methacrylate, stearyl methacrylate, oleyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate (preferably methyl methacrylate).
[0045]
Further, examples of the comonomer (d) include saturated fatty acid vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, and “vinyl versatate” (trade name) (preferably vinyl acetate); for example, styrene, α -Aromatic vinyl monomers such as methylstyrene and vinyltoluene (preferably styrene); for example, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile (preferably acrylonitrile);
[0046]
Further, the comonomer (d) is a monomer having at least one functional group in addition to one radical polymerizable unsaturated group in the molecule, if necessary, Monomers other than the bodies (b) and (c) (hereinafter sometimes referred to as functional comonomers) can also be copolymerized.
[0047]
Examples of such a functional comonomer include a functional group such as an amide group or a substituted amide group, an amino group or a substituted amino group, a hydroxyl group, a lower alkoxyl group, an epoxy group, a mercapto group, or a silicon-containing group. The monomer which has 2 or more of radically polymerizable unsaturated groups in a molecule | numerator can also be used.
[0048]
Specific examples of these functional comonomers include acrylamide, methacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methylol methacrylamide, Nn-butoxymethyl acrylamide, Ni-butoxymethyl acrylamide, N, N-dimethyl. Amide group or substituted amide group-containing monomers such as acrylamide and N-methylacrylamide; for example, aminoethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate Amino group-containing or substituted amino group-containing monomers such as N, N-diethylaminoethyl methacrylate;
[0049]
For example, hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol, methallyl alcohol, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate ;
[0050]
For example, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-n-butoxyethyl acrylate, 2-methoxyethoxyethyl acrylate, 2-ethoxyethoxyethyl acrylate, 2-n-butoxyethoxyethyl acrylate, 2-methoxyethyl methacrylate 2-ethoxyethyl methacrylate, 2-n-butoxyethyl methacrylate, 2-methoxyethoxyethyl methacrylate, 2-ethoxyethoxyethyl methacrylate, 2-n-butoxyethoxyethyl methacrylate, methoxypolyethylene glycol monoacrylate, methoxypolyethylene glycol monomethacrylate, etc. Lower alkoxyl group-containing monomers; for example, glycidyl acrylate, glycidyl methacrylate, glycidyl allyl ether, glycidyl methallyl ether Epoxy group-containing monomers; a mercapto group-containing monomers such as allyl mercaptan;
[0051]
For example, vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane, vinyltri-i-propoxysilane, vinyltri-n-butoxysilane, vinyltris (2-methoxyethoxy) silane , Vinyltris (2-hydroxymethoxyethoxy) silane, vinyltriacetoxysilane, vinyldiethoxysilanol, vinylethoxysiladiol, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, allyltrimethoxysilane, allyltri Ethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropyltris (2-methoxyethoxy) silane, 3-methacryloxy Propyl methyl diethoxy silane, 3-methacryloxypropyl dimethyl ethoxysilane, 3-acryloxypropyl dimethyl methoxy silane, a monomer having a silicon-containing group, such as 2-acrylamide-ethyl triethoxysilane;
[0052]
For example, divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, ethylene glycol di (meth) acrylate, 1,2-propylene glycol di (meth) acrylate, 1,3-propylene glycol di (meth) acrylate, 2,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, etc. A monomer group such as a monomer having one or more radically polymerizable unsaturated groups;
[0053]
The amount of such a comonomer (d) used is generally 40% by weight or less, preferably 10 to 30% by weight, particularly 100% by weight in total of the monomers (a) to (d). Preferably it is 10 to 25% by weight. The amount of the comonomer (d) used varies depending on the type of the monomer (d) and cannot be uniquely determined. However, the balance between the adhesive force and the tack and the balance between these and the cohesive force are adjusted as desired. Therefore, it can be appropriately selected in an amount within the above range to meet such purpose. If the amount of the comonomer (d) used is equal to or less than the upper limit of the above range, it is preferable because inconveniences such as an excessive decrease in tack do not occur. Moreover, the improvement of adhesive force or cohesion force can be expected by making the amount used more than the lower limit value.
[0054]
When the above functional comonomer is used, it should be 5% by weight or less, preferably 3% by weight or less, based on the total 100% by weight of all the monomers (a) to (d). . If the amount used is less than or equal to the upper limit, generation of agglomerates and destruction of the emulsified state during aqueous emulsion polymerization, decrease in storage stability of the resulting aqueous dispersion, or pressure-sensitive adhesive layer formed In the case where the pressure-sensitive adhesive layer is formed on the metal vapor deposition surface, it is preferable that problems such as vapor deposition loss do not occur.
[0055]
The acrylic copolymer (A) in the present invention is obtained by emulsion copolymerization of the monomers (a) to (d) described above in an aqueous medium.
[0056]
The surfactant that can be used in the present invention is not particularly limited, and various surfactants usually used for emulsion polymerization can be used.
[0057]
Among these surfactants, nonionic surfactants include, for example, polyoxyethylene alkyl (or alkenyl) ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; Polyoxyethylene alkyl phenyl ethers such as oxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether; for example, sorbitan higher fatty acid esters such as sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate;
[0058]
For example, polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; for example, polyoxyethylene higher fatty acid esters such as polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate Glycerin higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride; for example, polyoxyethylene / polyoxypropylene block copolymer;
[0059]
Examples of the anionic surfactants include higher fatty acid salts such as sodium oleate and sodium stearate; alkylaryl sulfonates such as sodium dodecylbenzene sulfonate; for example, sodium lauryl sulfate and sodium oleyl sulfate. Alkyl (or alkenyl) sulfate esters of
[0060]
For example, polyoxyethylene alkyl ether sulfate salts such as sodium polyoxyethylene lauryl ether sulfate and ammonium polyoxyethylene oleyl ether sulfate; for example, polyoxyethylene alkyl aryl ether sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate; Examples thereof include alkyl sulfosuccinic acid ester salts such as sodium octyl sulfosuccinate, sodium dioctyl sulfosuccinate, sodium polyoxyethylene lauryl sulfosuccinate and derivatives thereof; and the like.
[0061]
Furthermore, in the emulsion polymerization of the aqueous acrylic polymer of the present invention, a polyoxyethylene polycyclic phenyl ether type anionic surfactant represented by the following general formula (2) may be used as anionic surfactants. it can.
[0062]
[Chemical 1]

[0063]
(Where R²Is a hydrocarbon group containing one or more aromatic rings, M⁺Is Na⁺, K⁺NH_Four ⁺Represents a counter ion such as
[0064]
R in the general formula (2)²Is preferably derived from any of distyryl represented by the following three structural formulas or a mixture thereof.
[0065]
[Chemical formula 2]

[0066]
The length (value of n) of the polyoxyethylene chain in the anionic surfactant is generally in the range of 4 to 50, and preferably in the range of 5 to 45. Specific examples of these anionic surfactants include, for example, Hightenol NF-13, Hightenol NF-17 [trade name; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.], New Coal 707SF, New Coal 710SF, New Coal 714SF, New Coal 723SF, New Coal 740SF [trade name; manufactured by Nippon Emulsifier Co., Ltd.] and the like.
[0067]
Moreover, what substituted some hydrogen of the alkyl group of these emulsifiers with the fluorine can be used.
[0068]
Further, in the emulsion copolymerization of the acrylic copolymer (A) used in the present invention, a so-called “reactive emulsifier” having an unsaturated group capable of radical polymerization in the molecule may be used as necessary. it can.
[0069]
Examples of such reactive emulsifiers include “Eleminol JS-2”, “Eleminol RS-30” (manufactured by Sanyo Chemical Industries, Ltd.), “AQUALON HS-10N”, “AQUALON HS-20N” [ (Daiichi Kogyo Seiyaku Co., Ltd.), ADEKA rear soap SE-10N (Asahi Denka Kogyo Co., Ltd.), LATEMUL S-120, LATEMUL S-120A, LATEMUL S-180 Anionic reactive emulsifiers such as “Latemul S-180A” (manufactured by Kao Corporation); for example, “Aqualon RN-20”, “Aqualon RN-30”, “Aqualon RN-50” Made by Ichi Kogyo Seiyaku Co., Ltd.), ADEKA rear soap NE-10, ADEKA rear soap NE-20, ADEKA rear soap NE-30 (Asahi Denka Kogyo Co., Ltd.), RMA-564 Nonionic reactive emulsifiers such as “RMA-568” and “RMA-1114” (manufactured by Nippon Emulsifier Co., Ltd.).
[0070]
Furthermore, recently, when surfactants containing alkylphenyl groups, which are widely used in aqueous dispersions of acrylic copolymers, are contained in wastewater and discharged into rivers, etc., these surfactants are hydrolyzed. Alkylphenols generated by decomposition are taken up by organisms that live in these rivers and the seas into which they flow, especially fish and shellfish, and act as substances that destroy the endocrine function (endocrine) of these organisms (so-called environmental hormones). Became known. It has been pointed out that such alkylphenols have a high risk of entering the human body through the intake of these fishery products, or directly through the water of the waterworks that use water such as rivers.
[0071]
In the present invention, among the above nonionic and anionic surfactants, an acrylic copolymer aqueous solution that has solved the above-mentioned problems by selecting and using one that does not contain an alkylphenyl group as described above. A dispersion can also be obtained.
[0072]
Examples of such surfactants include nonionic surfactants such as polyoxyethylene alkyl (or alkenyl) ethers, sorbitan higher fatty acid esters, polyoxyethylene sorbitan higher fatty acid esters, polyoxyethylene higher fatty acid esters. Glycerin higher fatty acid esters, polyoxyethylene / polyoxypropylene / block copolymers, and the like, and anionic surfactants include higher fatty acid salts, alkylaryl sulfonates, alkyl (or alkenyl). Sulfuric acid ester salts, polyoxyethylene alkyl (or alkenyl) ether sulfuric acid ester salts, alkyl (or alkenyl) sulfosuccinic acid ester salts and derivatives thereof, polyoxyethylene of the above general formula (2) And the like can be used down polycyclic phenyl ether surfactant.
[0073]
These surfactants are preferably used in appropriate combination, and the amount used is generally 0.3 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the acrylic copolymer (A). More preferably, it can be used in an amount of about 0.5 to 2 parts by weight. If the amount of the surfactant used is less than or equal to the upper limit, problems such as a decrease in water resistance of the formed pressure-sensitive adhesive layer are unlikely to occur, and the pressure-sensitive adhesive layer is formed on the metal deposition surface. Even in the case where it is present, it is preferable because problems such as vapor deposition are unlikely to occur. On the other hand, if the amount used is equal to or greater than the lower limit, the generation of aggregates can be minimized during the emulsion polymerization of the acrylic copolymer (A), and the resulting aqueous pressure-sensitive adhesive composition Since the mechanical stability is excellent, it is preferable to appropriately select and use within the usage amount range.
[0074]
In the emulsion polymerization of the acrylic copolymer (A) used in the present invention, a water-soluble protective colloid is used together with the anionic and / or nonionic emulsifiers as long as the performance of the resulting copolymer is not adversely affected. It can also be used together.
[0075]
Examples of the water-soluble protective colloid include polyvinyl alcohols such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and modified polyvinyl alcohol; for example, cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose salt; and Natural polysaccharides such as guar gum; and the like, and these can be used singly or in combination. The amount of the water-soluble protective colloid used is about 0 to 0.5 parts by weight per 100 parts by weight of the monomers (a) to (d).
[0076]
Further, in emulsion polymerization, for example, persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide, and p-menthane hydroperoxide; A polymerization initiator such as hydrogen oxide is used. These polymerization initiators can also be used in any form of one kind or a combination of plural kinds. These polymerization initiators are preferably used in an amount of about 0.1 to 1 part by weight with respect to a total of 100 parts by weight of the monomers (a) to (d).
[0077]
In the emulsion polymerization, if desired, a reducing agent can be used in combination with a polymerization initiator. Examples of such reducing agents include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, glucose, and formaldehyde sulfoxylate metal salts; sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium metabisulfite, and the like. And reducing inorganic compounds. These reducing agents are preferably used in an amount of about 0.1 to 1 part by weight with respect to a total of 100 parts by weight of the monomers (a) to (d).
[0078]
Furthermore, a chain transfer agent can be used in the emulsion polymerization. Examples of such chain transfer agents include n-dodecyl mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, 2-ethylhexyl thioglycolate, 2-mercaptoethanol, trichlorobromomethane, and the like. These chain transfer agents are preferably used in an amount of about 0.1 to 1 part by weight with respect to a total of 100 parts by weight of the monomers (a) to (d).
[0079]
In addition, the said aqueous medium means the mixed solvent which consists of water and the organic solvent which is compatible with water and water. Examples of such organic solvents include methanol, ethanol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol. Examples thereof include monobutyl ether, diethylene glycol, acetone, and methyl ethyl ketone. As the aqueous medium in the emulsion copolymerization of the acrylic copolymer used in the present invention, a water-based medium is preferably used, and the content of the water-soluble organic solvent in the aqueous medium is usually 20% by weight. % Or less, preferably 10% by weight or less.
[0080]
The copolymerization temperature suitably employed in the emulsion copolymerization of the acrylic copolymer (A) used in the present invention is about 40 to 100 ° C, particularly about 50 to 90 ° C.
[0081]
The aqueous dispersion of the acrylic copolymer (A) thus obtained can be adjusted in pH with aqueous ammonia or the like, if necessary. Such a dispersion usually has a solid concentration of 30 to 50% by weight, a viscosity of 10 to 3000 mPa · s (BH type rotational viscometer, 25 ° C., 20 rpm; the same applies to the viscosity measurement conditions below), and a pH of about 2 to 9. Is preferred.
[0082]
The acrylic pressure-sensitive adhesive aqueous composition of the present invention comprises a polyepoxy compound (B) that can be dissolved or dispersed in water together with the water-dispersible acrylic copolymer (A) described above. .
[0083]
The polyepoxy compound (B) that can be used in the present invention can be dissolved or dispersed in water as described above, but preferably does not contain an alkylphenyl surfactant.
[0084]
As such a polyepoxy compound (B), for example, a polyol polyglycidyl ether compound, a polyacid polyglycidyl ester compound and the like can be preferably used.
[0085]
Examples of the polyol include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, neopentyl glycol, glycerol, diglycerol, polyglycerol, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol. And aliphatic or alicyclic polyols such as sorbitan, and examples of the polyacid include adipic acid.
[0086]
Among the polyepoxy compounds (B) that can be used in the present invention, specific examples of the polyol polyglycidyl ether compound include, for example, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol (n = about 4, 9, 13, 22) Diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol (n = about 3, 11 etc.) diglycidyl ether, neopentyl glycol diglycidyl ether, glycerol diglycidyl ether, glycerol Triglycidyl ether, diglycerol triglycidyl ether, polyglycerol (n = about 4, 6, etc.) polyglycidyl ether, trimethylolpropane poly Examples include ricidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, and specific examples of polyacid polyglycidyl ester compounds include, for example, adipic acid diglycidyl ester. it can.
[0087]
Particularly preferred among these polyepoxy compounds (B) are ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, diglycerol triglycidyl ether, sorbitol polyglycidyl ether, sorbitan poly Glycidyl ether.
[0088]
As such an aqueous liquid of the polyepoxy compound (B), for example, various epoxy-based crosslinking agents sold by Nagase Kasei Kogyo Co., Ltd. under the trade name `` Denacol '' can be suitably used. -313, Denacol EX-314, Denacol EX-411, Denacol EX-512, Denacol EX-521, Denacol EX-611, Denacol EX-614 can be used particularly preferably.
[0089]
The polyepoxy compound (B) needs to be used in an amount of 0.5 to 10 parts by weight, preferably 0.5 to 8 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the acrylic copolymer (A). It is good to use part. If the amount used is less than the lower limit value, the cohesive force essential as a pressure-sensitive adhesive tends to be insufficient, and it is not preferable because sufficient substrate adhesion is not exhibited. If the amount is too large, the physical properties of the desired pressure-sensitive adhesive will not be further increased, and the polyepoxy compound will be wasted, and in addition, there may be inconveniences such as reduced adhesion to the adherend. It is not preferable.
[0090]
The acrylic pressure-sensitive adhesive aqueous composition of the present invention can further contain a tackifying resin, if necessary. Examples of tackifying resins that can be used in the present invention include coumarone / indene resin, terpene resin, terpene / phenol resin, rosin resin, pt-butylphenol / acetylene resin, phenol / formaldehyde resin, xylene / formaldehyde resin, petroleum carbonization. A hydrogen resin, a hydrogenated hydrocarbon resin, a terpin resin, or the like can be used. From the viewpoints of low-temperature adhesive strength, curved surface adhesion, and the like, rosin resin and petroleum hydrocarbon resin are preferably used. The softening point of the tackifying resin is generally 70 to 180 ° C., preferably 100 to 180 ° C., particularly preferably 120 to 170 ° C., and its weight average molecular weight is generally 5000 or less, particularly 2000 to 4000 is preferred. Furthermore, the tackifier resin that can be used in the present invention is preferably an aqueous dispersion.
[0091]
Examples of such a tackifier resin include “Superester E-625A”, “Superester E-650”, Superester KE-788 ”(manufactured by Arakawa Chemical Industries, Ltd.),“ Harriester SK-130D ”. ”,“ Harristar SK-508 ”,“ LP-532 NF ”(manufactured by Harima Kasei Co., Ltd.), etc .; for example,“ QME-100 ”,“ QME-125ps ”,“ QME-800 ”[ The above-mentioned petroleum-based hydrocarbon resins such as Toho Chemical Industry Co., Ltd.] and the like can be mentioned, and among these, substantially free of alkylphenyl surfactants, “Superester KE-788”, “LP-532NF”, “QME-125ps”, “QME-800” are preferably used.
[0092]
When the tackifying resin is used in the present invention, the amount used is generally 2 to 45 parts by weight, preferably about 4 to 35 parts by weight, with respect to 100 parts by weight of the acrylic copolymer (A). There should be.
[0093]
The acrylic pressure-sensitive adhesive aqueous composition of the present invention is also used by adding various modifying resins such as synthetic rubber, natural rubber, and ethylene-vinyl acetate copolymer resin, as long as the desired performance is not impaired. can do. The addition amount of these various modifying resins can be appropriately selected from the viewpoint of the balance between the adhesive force and cohesive force to the nonpolar polymer, and for example, 0 to 30 parts by weight with respect to a total of 100 parts by weight of the acrylic copolymer. The amount added is preferably about 0 to 20 parts by weight.
[0094]
Further, the pressure-sensitive adhesive composition of the present invention may contain, if necessary, a plasticizer, a wetting agent, a colorant, an inorganic filler, a stabilizer, an antifoaming agent, an antiseptic, an antifungal agent, and the like. It can also be used.
[0095]
The aqueous acrylic pressure-sensitive adhesive composition of the present invention, from the viewpoint of ease of production and the like, the acrylic copolymer (A) and the polyepoxy compound (B), and the pressure-sensitive adhesive used as necessary It is preferable to prepare the resin by mixing the imparting resin in the form of an aqueous liquid and, if necessary, adding and mixing the above-mentioned blends such as a wetting agent and a thickener. Moreover, since it is preferable that the obtained pressure-sensitive adhesive aqueous composition does not substantially contain an alkylphenyl-based surfactant, a polyepoxy compound, a tackifier resin, a wetting agent, a thickener, etc. However, it is preferable that the alkylphenyl surfactant is not substantially contained.
[0096]
The acrylic pressure-sensitive adhesive aqueous composition of the present invention thus obtained has a solid content concentration of generally 30 to 70% by weight, preferably 50 to 70% by weight; viscosity of generally 100 to 20000 mPa · s, transfer method In the case of using for the transfer method, the pH is generally 3000 to 20000 mPa · s; the pH is generally about 3 to 8, and the pH of 4 to 8.5 is preferable for the transfer method.
[0097]
As a method for forming a pressure-sensitive adhesive layer using the acrylic pressure-sensitive adhesive aqueous composition of the present invention, the pressure-sensitive adhesive composition is formed on a substrate such as paper or plastic film, for example, a roll. A direct method of directly applying and drying using a generally known means such as a coater or knife coater can be adopted, and a release material comprising a paper or a film obtained by releasing the pressure-sensitive adhesive composition with a silicone resin or the like. After applying and drying using the same means to form a pressure-sensitive adhesive layer, the base material is overlaid and pressed on the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive is applied onto the base material. Although a transfer method for transferring the layer can be used, it is more preferable to use the transfer method.
[0098]
In the above transfer method, various types of wetting agents, thickeners, and viscosity improvers are usually used in order to prevent repelling and twisting in the pressure-sensitive adhesive composition upon application to the release material. The pressure sensitive adhesive composition is thickened and used.
[0099]
As the above wetting agent, sulfosuccinate ester type anionic surfactants exemplified in the anionic surfactant are well known, but according to the study by the present inventors, this wetting agent is It has been found that the water resistance of the pressure-sensitive adhesive layer formed by the composition of the present invention tends to decrease and is not necessarily good.
[0100]
What has been clarified by further studies by the present inventors is that the pressure-sensitive adhesive composition of the present invention includes a nonionic wetting agent, specifically, from the viewpoint of the water resistance of the resulting pressure-sensitive adhesive layer. Specifically, it is preferable to use an acetylenic diol type nonionic wetting agent having the following structural formula (3).
[0101]
[Chemical 3]

[0102]
(Here, the sum of m1 and m2 is in the range of 1-40)
[0103]
As such an acetylenic diol type nonionic wetting agent, for example, various wetting agents sold by Air Products Japan Co., Ltd. under the trade name “Surfinol 400 Series” can be suitably used. The amount of acetylenic diol type nonionic wetting agent used is, for example, 0.1 to 1.5 parts by weight, preferably 0.2 to 1 part by weight, more preferably 0.3 to 0.5 parts by weight, based on 100 parts by weight of the acrylic pressure-sensitive adhesive aqueous composition. The range of the part is good. If the amount of the wetting agent used is equal to or greater than the lower limit, there is no occurrence of repellency or pinholes on the coated surface when the pressure-sensitive adhesive composition is applied to a release material, and a good coating film is formed. In addition, it is preferable because it exhibits sufficient water resistance, and if it is less than or equal to the upper limit value, it is preferable because sufficient adhesion to the adherend and sufficient adhesion to the substrate are exhibited.
[0104]
Furthermore, examples of the thickener and viscosity improver include sodium polyacrylate, the PVA, the cellulose derivative, and an aqueous dispersion type poly (meth) acrylic acid copolymer thickener that thickens with alkali. can do. The amount of these used can be appropriately determined according to the desired viscosity and viscosity, and is 0 to 10 parts by weight, preferably 0 as a solid content with respect to a total of 100 parts by weight of the acrylic pressure-sensitive adhesive aqueous composition. The range is ˜5 parts by weight.
[0105]
In the use of the acrylic pressure-sensitive adhesive aqueous composition of the present invention, examples of a substrate that can be suitably used include polyethylene terephthalate, polycarbonate, polystyrene, polyvinyl chloride, polyamide, thermoplastic polyurethane, petroleum hydrocarbon. Thermoplastic resin film or sheet having a softening point of 60 ° C or higher such as resin, coumarone resin, rosin derivative, natural resin, natural asphalt; for example, plain paper, fine paper, art paper, cast paper, thermal recording paper, cardboard, cardboard Papers such as phenol resins, melamine resins, urea resins, epoxy resins, unsaturated polyester resins, urethane resins, etc .; for example, iron, steel, aluminum, nickel, chromium, cobalt, stainless steel , Zinc-treated steel sheet, copper-plated steel sheet, copper, brass, etc. Foil genus or metal alloy; e.g., glass, and the like can be exemplified inorganic sheet such as a ceramic. Polyethylene terephthalate (PET), biaxially stretched polypropylene (OPP), and unstretched polypropylene (CPP) are preferably used, and in particular, use on a vapor deposition surface of a metal vapor deposition film such as aluminum is preferred. The thickness of these substrates is generally about 10 to 2000 μm, preferably about 20 to 100 μm.
[0106]
【Example】
The present invention will be described more specifically with reference to the following examples, comparative examples, and reference examples, but the present invention is not limited to these examples.
In addition, preparation of a test piece and various physical property tests followed the following test methods.
[0107]
(1) Preparation of pressure-sensitive adhesive sheet for testing
On the release paper (EN Cream-2; manufactured by Oji Tac Sales Co., Ltd.) surface-treated with a silicone release agent, the coating amount after drying is 20 g / m²The pressure-sensitive adhesive composition was applied with a doctor blade so that the pressure-sensitive adhesive layer was dried at 110 ° C. for 60 seconds with a hot-air circulating drier to form a pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive layer was coated on the surface. The aluminum vapor-deposited surface of the material (aluminum vapor-deposited OPP or aluminum vapor-deposited PET) is bonded with a hand roller, then pressed with a hand press all day and night, and then cured in a constant temperature bath at 40 ° C for 3 days for pressure-sensitive adhesion for testing. A sheet was used.
[0108]
(2) PET Measurement of permanent adhesion
A PET film [E5001; manufactured by Toyobo Co., Ltd.] is adhered to a smooth polyethylene (PE) plate (2 x 125 x 150 mm) with double-sided tape [No.501F; manufactured by Nitto Denko Corporation] and left for 24 hours or longer. The test piece (adhered body) was used, and the test piece (25 mm x 150 mm) cut out from the test pressure-sensitive adhesive sheet prepared in the previous section (1) was pressure-bonded to this according to the method of JIS Z 0237. Next, after being left for 24 hours or longer in an atmosphere of 23 ° C and 65% RH, a 180 ° peel test was performed in an atmosphere of 23 ° C and 65% RH in accordance with JIS Z 0237 and at a peel rate of 300 mm / min. The peel strength (N / 25mm) was measured. The peel strength is, for example, preferably 8 N / 25 mm or more, particularly 10 N / 25 mm or more.
[0109]
Moreover, the fracture | rupture form of the peeling surface was determined according to the following reference | standard, observing the ratio of the pressure sensitive adhesive currently transferred to the test board visually after a measurement.
[0110]
〔Evaluation criteria〕
○: Adhesive does not transfer to the test plate.
Δ: Less than 50% of the adhesive of the test piece is transferred to the test plate.
X: The adhesive of 50% or more of the test piece is transferred to the test plate.
[0111]
(3) Measurement of water-resistant adhesion
In the previous section (2), after leaving the test plate obtained by laminating the test pieces for 24 hours or more, immerse it in water at 40 ° C for 48 hours or more, take it out from the water just before the measurement, and wipe off the excess water. The water-resistant adhesive strength (N / 25 mm) was measured by peeling at 180 ° in the same manner as in the previous item (2) except that the measurement was performed from the above. The water-resistant adhesive strength is preferably, for example, 5 N / 25 mm or more, particularly 7 N / 25 mm or more.
[0112]
Moreover, transparency determined the transparency of the adhesive surface of the adhesive sheet after adhesive force measurement by visual evaluation.
[0113]
〔Evaluation criteria〕
○: Transparency of the pressure-sensitive adhesive surface is good (the pressure-sensitive adhesive surface is not whitened).
Δ: The pressure-sensitive adhesive surface is slightly whitened.
X: The pressure-sensitive adhesive surface is completely whitened.
[0114]
(Four) Edge lift measurement
A 130 mmφ PE rod is degreased with ethyl acetate to form an adherend, and then the test piece (16 mm × 25 mm) release paper cut from the pressure-sensitive adhesive sheet for test prepared in the previous section (1) is peeled off and the above is removed. The substrate was bonded to the adherend by hand, and after pressure bonding, it was left at 23 ° C. × 65% RH for 24 hours. After 24 hours, the state of peeling due to rebound from the adherend of the pressure-sensitive adhesive sheet for test was determined from the total peeling length on both sides.
[0115]
〔Evaluation criteria〕
○: 0 to less than 2 mm
Δ: Less than 2-10mm
×: 10-25mm
[0116]
(Five) Measurement of substrate adhesion
The surface of the aluminum plate (thickness 1 mm) was polished with water-resistant abrasive paper # 280, washed with water, degreased with ethyl acetate, and an epoxy adhesive [# 16051; manufactured by Konishi Co., Ltd.] was uniformly and thinly applied thereto. Remove the test piece (25mm x 150mm) release paper cut from the test pressure-sensitive adhesive sheet prepared in the previous section (1), and attach the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet to the epoxy adhesive surface. The samples were put together and pressed with a squeegee and left for a whole day and night.
[0117]
The adhesive strength (N / 25 mm) of the above sample was measured by 180 ° peeling under the same conditions as in the previous section (2) except that the peeling speed was 500 mm / min. The substrate adhesion is preferably, for example, 7 N / 25 mm or more, particularly 14 N / 25 mm or more.
[0118]
(6) Adhesive residue on adherend
Remove the liquid (detergent solution) from the bottle of synthetic detergent for the kitchen [Family Compact 300Ml; manufactured by Kao Corporation], carefully remove the surface label by hand, wash with water, and degrease the bottle surface with ethanol. Is the adherend. Release the release paper from the test piece (105mm x 54mm square) cut out from the test pressure-sensitive adhesive sheet prepared in the previous section (1), and apply it to the adherend by hand. A sample was used.
[0119]
Next, the detergent solution extracted above was put in a large container, and the sample was completely immersed in the detergent solution, covered with aluminum foil and left in a constant temperature bath at 40 ° C. for 48 hours. After leaving for 48 hours, take out the container from the thermostatic chamber, let it cool at room temperature, take out the sample from the detergent solution, wash the sample with water, wipe off excess moisture with tissue paper, etc., from the bottle that is the adherend, The state of transfer of the pressure-sensitive adhesive to the adherend when the pressure-sensitive adhesive sheet was peeled off at high speed or low speed by hand was determined according to the following criteria.
[0120]
[Criteria]
○: The pressure-sensitive adhesive does not transfer to the adherend at both high speed and low speed peeling.
Δ: Transfer occurs at high speed peeling, but does not transfer at low speed peeling.
X: The pressure-sensitive adhesive is transferred to the adherend at both high speed and low speed peeling.
[0121]
(7) Vapor deposition missing
The test piece (50mm x 150mm) cut out from the test pressure-sensitive adhesive sheet prepared in the previous section (1) is peeled off, and then left in a constant temperature and humidity chamber adjusted to 75 ° C x 95% RH for 7 days. The omission of aluminum vapor deposition of the material was visually evaluated and judged according to the following criteria.
[0122]
[Criteria]
○: There is no omission of aluminum deposition on the base material.
(Triangle | delta): Aluminum vapor deposition of a base material falls out less than 50%.
X: Aluminum vapor deposition of the substrate is 50% or more.
[0123]
(8) Cohesion
Using the test piece (25 mm × 150 mm) cut out from the test pressure-sensitive adhesive sheet prepared in the previous section (1), the holding force is measured. The holding force measurement method was based on JIS Z 0237, measured the drop time at a load of 1,000 g, 5 reciprocations, a measurement temperature of 60 ° C. and a measurement time of 1,000 minutes, and judged the cohesive strength according to the following evaluation criteria. .
[0124]
〔Evaluation criteria〕
○: Fall time 1,000-800 minutes
Δ: Fall time 800-400 minutes
×: Drop time 400 to 0 minutes
[0125]
<Preparation of aqueous dispersion of water-dispersed acrylic copolymer>
[0126]
Production Example 1
In a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen introduction tube and monomer premix feed pump, 50 parts by weight of deionized water and “Hytenol NF-17” [polyoxyl as a surfactant Ethylene (n = 17.5) distyrylphenyl ether sulfate ammonium salt type anionic surfactant (active ingredient concentration 95% by weight); Daiichi Kogyo Seiyaku Co., Ltd.] (NF-17) 0.1 part by weight was charged, temperature The internal temperature was raised to 70 ° C. using a water bath with a control device.
[0127]
Meanwhile, in a separate container, 28.1 parts by weight of deionized water, 0.9 part by weight of the surfactant “NF-17”, 76.8 parts by weight of monomer butyl acrylate (BA), 21.6 parts by weight of methyl methacrylate (MMA), acrylic acid ( AA) 1.5 parts by weight and 0.1 part by weight of 2-methacryloyloxyethyl dihydrogen phosphate ["Posmer M" manufactured by Unichemical Co., Ltd.] and 0.3 parts by weight of chain transfer agent n-dodecyl mercaptan (n-DM) are stirred. To prepare a monomer premix.
[0128]
The contents were then stirred while the reactor space was replaced with nitrogen, and 0.74 parts by weight of 9% by weight “Perbutyl H” (t-butyl hydroperoxide) and 20% by weight “Longalite” (sodium formaldehyde sulfoxylate) 0.333 part by weight was charged.
[0129]
Next, the monomer premix was added dropwise together with 10.55 parts by weight of 1.4% “Perbutyl H” and 10.55 parts by weight of “Longalit” 1.4% by weight for emulsion polymerization. After the dropwise addition of the monomer premix, etc., stirring is continued for about 1 hour at the same temperature, and then the reaction mixture is cooled to 30 ° C., adjusted to pH with aqueous ammonia, and the water-dispersed acrylic copolymer is prepared. An aqueous dispersion was prepared. The obtained aqueous dispersion had a solid content of about 48% by weight, a pH of 7.2, a viscosity of 700 mPa · s (25 ° C., BH type rotational viscometer 20 rpm), an average particle diameter of the dispersed particles of about 116 nm, and a copolymer glass. The transition point (Tg) was about −33 ° C., and the weight average molecular weight (Mw) was about 200,000.
[0130]
Production Example 2
In Production Example 1, AA was not used as shown in Table 1, and an aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Production Example 1 except that MMA was added for the change in AA. In addition, since a considerably large amount of agglomerates was generated during the emulsion polymerization, only the portion that could be barely filtered was used. Table 1 shows the monomer composition used in the copolymerization, the amount of chain transfer agent and surfactant used, and the solid content, pH, viscosity and average particle size of the dispersed particles of the resulting acrylic copolymer aqueous dispersion, etc. Table 2 shows characteristic values such as the glass transition point (Tg) and weight average molecular weight (Mw) of the acrylic copolymer.
[0131]
Production Examples 3-4
In Production Example 1, as shown in Table 1, the amount of “phosmer M” used was changed to 0.5% by weight, or this was not used, and the amount of change in “Fosmer M” was the same as in Production Example 1 except that BA was adjusted. Thus, an aqueous dispersion of an acrylic copolymer was obtained. Table 1 shows the monomer composition used in the copolymerization, the amount of chain transfer agent and the surfactant used, and the characteristic values of the resulting acrylic copolymer aqueous dispersion and the characteristic values of the acrylic copolymer. 2 is shown.
[0132]
Production Examples 5-7
In Production Example 1, as shown in Table 1, 2-ethylhexyl acrylate (EHA) is used in place of BA, or the glass transition point of the acrylic copolymer is changed by changing the use ratio of BA and MMA or not using MMA. An aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Production Example 1 except that (Tg) was changed. Table 1 shows the monomer composition used in the copolymerization, the amount of chain transfer agent and the surfactant used, and the characteristic values of the resulting acrylic copolymer aqueous dispersion and the characteristic values of the acrylic copolymer. 2 is shown.
[0133]
Production Examples 8-10
In Production Example 1, as shown in Table 1, except that the amount of chain transfer agent (n-DM) used was changed or the weight average molecular weight (Mw) of the acrylic copolymer was changed by not using it. Similarly, an aqueous dispersion of an acrylic copolymer was obtained. Table 1 shows the monomer composition used in the copolymerization, the amount of chain transfer agent and the surfactant used, and the characteristic values of the resulting acrylic copolymer aqueous dispersion and the characteristic values of the acrylic copolymer. 2 is shown.
[0134]
Production Example 11
In Production Example 1, the amount of the surfactant “NF-17” initially charged in the reactor is 0.01 parts by weight, and the amount of the surfactant “NF-17” for preparing the monomer premix is increased accordingly. An aqueous dispersion of acrylic copolymer was obtained in the same manner as in Production Example 1 except that the average particle size of the acrylic copolymer dispersed particles was changed to 0.99 parts by weight. Table 1 shows the monomer composition used in the copolymerization, the amount of the chain transfer agent and the surfactant used, the characteristic values of the obtained acrylic copolymer aqueous dispersion, and the characteristic values of the acrylic copolymer.
[0135]
[Table 1]

[0136]
[Table 2]

[0137]
<Preparation of water-based acrylic pressure-sensitive adhesive composition>
[0138]
Example 1
With respect to 208 parts by weight of the aqueous acrylic copolymer dispersion obtained in Production Example 1 (about 100 parts by weight as an acrylic copolymer), a water-soluble polyepoxy compound [“Denacol EX-512”; glycerol polyglycerol Type polyepoxy compound, epoxy equivalent 173; manufactured by Nagase Kasei Kogyo Co., Ltd.] (EX-512) 3.6 parts by weight, acetylenic diol-based wetting agent ["Surfinol 440"; manufactured by Air Products Japan Co., Ltd.] 0.624 parts by weight, And 4.16 parts by weight of an aqueous solution obtained by diluting a polyether thickener [“Adecanol UH-550” manufactured by Asahi Denka Kogyo Co., Ltd.] 2.5 times with deionized water and stirring with a homomixer to obtain a solid content of 46.2 An acrylic pressure-sensitive adhesive aqueous composition having a weight percent, pH 7.2, and a viscosity of about 12,600 mPa · s (25 ° C., BM type rotational viscometer 60 rpm) was prepared.
Using this composition, a pressure-sensitive adhesive sheet for test was prepared according to the method (1), and the physical properties of the pressure-sensitive adhesive sheet were measured according to the test methods (2) to (7). Table 3 shows the blended composition of the pressure-sensitive adhesive composition, and its characteristic values such as pH, viscosity and solid content, and Table 4 shows the physical properties of the pressure-sensitive adhesive sheet.
[0139]
Example 2 and Comparative Example 1
In Example 1, instead of using 3.6 parts by weight of “EX-512”, an acrylic pressure-sensitive adhesive aqueous composition was prepared in the same manner as in Example 1 except that 0.5 part by weight was used or this was not used. Table 3 shows the composition and characteristic values of the obtained pressure-sensitive adhesive composition, and Table 4 shows the physical properties of the pressure-sensitive adhesive sheet.
[0140]
Example 3
In Example 1, an acrylic pressure-sensitive adhesive aqueous composition was prepared in the same manner as Example 1 except that 4.8 parts by weight of "EX-411" was used instead of 3.6 parts by weight of "EX-512". Table 3 shows the composition and characteristic values of the obtained pressure-sensitive adhesive composition, and Table 4 shows the physical properties of the pressure-sensitive adhesive sheet.
[0141]
Examples 4-7 and Comparative Examples 2-7
In Example 1, instead of using 208 parts by weight of the acrylic copolymer aqueous dispersion of Production Example 1, as shown in Table 3, each of the acrylic copolymer aqueous dispersions of Production Examples 2 to 11 was used. An acrylic pressure-sensitive adhesive aqueous composition was prepared in the same manner as in Example 1 except that the acrylic copolymer was used in an amount of about 100 parts by weight, depending on the solid content. Table 3 shows the composition and characteristic values of the obtained pressure-sensitive adhesive composition, and Table 4 shows the physical properties of the pressure-sensitive adhesive sheet.
[0142]
[Table 3]

[0143]
[Table 4]

[0144]
【The invention's effect】
The aqueous acrylic pressure-sensitive adhesive composition of the present invention contains a carboxyl group and an acidic phosphate group in the molecule, and has a specific glass transition point (Tg) and a weight average molecular weight (Mw). A specific amount range of a polyepoxy compound (B) that can be dissolved or dispersed in water with respect to an acrylic copolymer (A) whose dispersed particles have an average particle diameter of 200 nm or less. It is what.
[0145]
The acrylic pressure-sensitive adhesive aqueous composition of the present invention configured as described above has a high degree of transparency showing excellent substrate adhesion to various polymer films, particularly metal vapor-deposited film substrates. The pressure-sensitive adhesive layer thus obtained can be applied to a curved surface while maintaining excellent adhesion and cohesive strength to various adherends essential as a pressure-sensitive adhesive. Excellent performance as a pressure-sensitive adhesive, such as "edge lift" resistance to the body, water resistance, especially when a metal-deposited film is used as a base material, prevention of deposition loss, and lack of adhesive residue on the adherend after peeling. Demonstrate.

Claims (9)

(A) and (B) below
(A) The molecule contains a carboxyl group and an acidic phosphate group, has a glass transition point (Tg) of −25 ° C. or less, has substantially no gel content before crosslinking, and has a weight average molecular weight (Mw ) Is a water dispersible acrylic copolymer in the range of 100,000 to 600,000, 100 parts by weight of the acrylic copolymer having an average particle diameter of 200 nm or less, and
(B) 0.5-10 parts by weight of a polyepoxy compound that can be dissolved or dispersed in water,
An acrylic pressure-sensitive adhesive aqueous composition comprising: The pressure-sensitive adhesive aqueous composition according to claim 1, wherein the acrylic copolymer is obtained by copolymerizing (meth) acrylic acid ester by 50% by weight or more. Acrylic copolymer has the following monomers (a) to (d),
(a) 54-99.4% by weight of an acrylate ester represented by the following general formula (1) and having a glass transition point of the homopolymer of −50 ° C. or lower,
CH ₂ = CH-COOR ¹ (1)
(In the formula, R ¹ represents a linear or branched alkyl group having 4 to 12 carbon atoms)
(b) 0.5 to 3% by weight of an α, β-unsaturated mono- or di-carboxylic acid having 3 to 5 carbon atoms,
(c) 0.01 to 3% by weight of a monomer containing one radical polymerizable unsaturated group and acidic phosphate group in the molecule, and
(d) 40% by weight or less of a comonomer other than the monomers (a) to (c), copolymerizable with the monomers (a) to (c),
[However, the total amount of monomers (a) to (d) used is 100% by weight.]
The aqueous pressure-sensitive adhesive composition according to claim 1, which is obtained by emulsion copolymerization. The pressure-sensitive adhesive aqueous composition according to claim 4, wherein the acrylic copolymer is emulsion-copolymerized in the presence of a surfactant substantially free of an alkylphenyl surfactant. The pressure-sensitive adhesive aqueous composition according to claim 1, wherein the polyepoxy compound is selected from a polyol polyglycidyl ether compound or a polyacid polyglycidyl ester compound. The pressure-sensitive adhesive aqueous composition according to claim 1, wherein the pressure-sensitive adhesive aqueous composition further contains an acetylenic diol wetting agent. The pressure-sensitive adhesive aqueous composition according to claim 7, wherein the content of the acetylenic diol wetting agent is in the range of 0.1 to 1.5 parts by weight as an active ingredient with respect to 100 parts by weight of the acrylic copolymer. The pressure-sensitive adhesive aqueous composition according to any one of claims 1 to 7, which contains substantially no alkylphenyl surfactant in the pressure-sensitive adhesive aqueous composition. The pressure-sensitive adhesive aqueous composition according to any one of claims 1 to 8, which is used for forming a pressure-sensitive adhesive layer on a vapor deposition side surface of a metal vapor-deposited film.