JP4550292B2

JP4550292B2 - Adhesive type identification sheet and method for producing adhesive type identification sheet

Info

Publication number: JP4550292B2
Application number: JP2001001020A
Authority: JP
Inventors: 正紀上杉; 盈夫倉本; 滝男伊藤
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2001-01-09
Filing date: 2001-01-09
Publication date: 2010-09-22
Anticipated expiration: 2021-01-09
Also published as: JP2002200060A

Description

【０００１】
【発明の属する技術分野】
本発明は指紋や足跡、タイヤ跡等の採取に使用する粘着剤式鑑識用シート及びその粘着剤式鑑識用シートの製造方法に関するものである。
【０００２】
【従来の技術】
犯罪鑑識では、潜在的に付着した指紋や足跡等の情報を視覚化して採取し、その情報を捜査官、裁判官、弁護士等に客観的に伝達しなければならない。
旧来、指紋を採取するには、手の指が接触した箇所に指紋隆線の汗腺開口からの分泌物が付着するので、アルミナ粉末等をダスタ−刷毛等で少しづつ撒布し、穂先で軽く払うようにして、指紋隆線の部分だけに粉を付着させ指紋を浮き上げ、この浮き上げ指紋をゼラチン紙に転写する方法が伝統的に用いられていた。
【０００３】
しかしながら、これらのゼラチン紙を使用する方法では、夏場において自動車のフレ−ム等に付着した指紋を採取する場合、該フレ−ムが７０℃以上もの温度になることが往々にしてあり、５０℃で軟化溶融するゼラチン質では流動してしまい指紋を採取できない。
また、環境温度の如何によっては、指紋採取後、周囲温度が上昇し指紋が変化してしまい、鑑識に供し得ないことも往々にしてある。更に、冬場でも暖房器具の近傍での指紋採取は至難である。更にまた、ゼラチン質が親水性であるため湿気に弱く、水気を含む場所では膨潤のために使用できないこともある。
【０００４】
そこで、上記ゼラチン紙に代え、アクリル系粘着シートを使用することが提案されている（特開平３−８０８３３号）。
しかしながら、アクリル系粘着剤では、凹凸の急峻の隆起面に付着した指紋を採取する場合、採取対象面にアクリル系粘着シートを密接すると、角等の急峻な面変化箇所で粘着剤層が伸びて薄肉化してその箇所での粘着剤量が不足し正確な採取が難しくなる。
一方、粘着剤層を厚くすると、それだけ粘着力がアップし、アクリル系粘着剤の本来の高い粘着力と相俟って、採取対象面の塗装の剥離等、原状破損が生じ易くなる。
【０００５】
そこで、本発明者等においては、ウレタン系粘着剤層ではアクリル系粘着剤層に較べて貯蔵弾性率が小であり、ドアノブ等の面変化の急峻な指紋採取対象面にウレタン粘着シートを密接に当接しても、ウレタン系粘着剤層の曲げ歪みに伴う伸びで生じる薄肉化を軽度にとどめ得、凹凸の急峻な採取対象面でもウレタン系粘着剤量を充分に保有させて指紋採取を満足に行い得ることに着目してウレタン系粘着シートを鑑識シートとして用いることを既に提案した（特願平１１−２１８４０３号）。
【０００６】
更に、従来の指紋採取方法では、ゼラチン紙やアクリル系粘着シートに転写した指紋痕跡を再度、黒色台紙に転写して指紋原紙を作りこれを保管しており、採取のための転写と、保管のための転写の２回の転写が必要であり、取扱が煩雑である。
そこで、本発明者等においては、透明支持フィルムの片面にウレタン系粘着剤を塗工した粘着シートを、微粉末の撒布や薬品噴霧により視覚化した指紋痕跡に対し異色とした台紙の片面に貼着して成る採取シートを用意しておき、台紙を剥離して粘着シートのウレタン系粘着剤層に前記の視覚化した指紋痕跡を転写し、ついでこの転写粘着シートを上記台紙の離型処理面に再貼着して指紋痕跡を採取することを既に提案した（同上特願平１１−２１８４０３号）。
【０００７】
【発明が解決しようとする課題】
しかしながら、指紋隆線部分にアルミ粉等を付着させて浮き上げさせた指紋痕跡をウレタン系粘着シートに満足に転写させるには、粘着剤層の厚みをある程度厚くする必要がある。
而るに、粘着剤層は通常、溶剤で希釈した粘着剤溶液を塗布し、この塗布溶液を溶剤の蒸発で凝固させる（乾燥させる）ことにより形成され、表面側から乾燥凝固されていき、内部に至るほど溶剤の蒸発が遅くなる結果、ある塗布厚以上では、表面に乾燥凝固スキン膜が形成されたのちに内部の粘着剤溶液から溶剤が蒸発されそのスキン膜が破られて粘着層の表面外観がクレータ状になることがあり、指紋痕跡を満足に転写させるのに必要な上記のウレタン系粘着層厚みでは、粘着層の表面がクレータ状になって指紋痕跡の転写を高精度で行い難い。
【０００８】
本発明の目的は、粘着剤としてタックが低いウレタン系粘着剤を用いて粘着シートにより指紋採取を高精度で、かつ指紋採取対象面を傷付けることなく容易に行い得る粘着剤式鑑識用シート及びその製造方法を提供することにある。
【０００９】
【課題を解決するための手段】
本発明に係る粘着剤式鑑識用シートは、粘着シートの粘着面で転写・採取を行う鑑識用シートにおいて、粘着剤層がウレタン系粘着剤膜の積層貼り合わせ構造とされていることを特徴とする構成であり、台紙から剥離した透視性粘着シートの粘着面で転写・採取を行い、該粘着シートを台紙に再貼り付けする鑑識用シートの形態で実施でき、通常、粘着剤層の貯蔵弾性率が３ｅ＋０４〜８ｅ＋０５ｄｙｎ／ｃｍ、厚みが８０〜１０００μmとされ、また粘着剤層の粘着力が２Ｎ/20mm以下とされる。
【００１０】
本発明に係る粘着剤式鑑識シートの製造方法は、台紙から剥離した透視性粘着シートの粘着面で転写・採取を行い、該粘着シートを台紙に再貼り付けする鑑識用シートを製造する方法であり、形成したウレタン系粘着剤膜を台紙の離型面に転写し、透視可能な基材に同上ウレタン系粘着剤の塗布膜を形成し、該塗布膜面に上記台紙を接着剤膜面において貼り合わせることを特徴とする構成である。
【００１１】
【発明の実施の形態】
以下、図面を参照しつつ本発明の実施の形態について説明する。
図１は本発明に係る粘着剤式鑑識用シートを示している。
図１において、１はウレタン粘着シートであり、支持フィルム１１を透明とし、ウレタン粘着剤層１２をウレタン系粘着剤膜１２１，１２１の積層貼り合わせ構造としてある。２は台紙であり、表面に事件番号記入欄、採取日時の記入欄、採取物件記入欄、採取者氏名記入欄、立会人氏名記入欄等を印刷した紙質シート２１の裏面に、離型性の黒色または白色プラスチック離型フィルム２２を接着または融着してあり、離型性プラスチックフィルム面２２に前記ウレタン粘着シート１のウレタン系粘着剤層面１２を貼着してある。
【００１２】
上記ウレタン系粘着剤層の厚みは８０〜１０００μm、好ましくはは１００〜３００μmとし、粘着力は２Ｎ/20mm以下、好ましくはは１．８Ｎ/20mm以下とし、貯蔵弾性率は３ｅ＋０４〜８ｅ＋０５ｄｙｎ／ｃｍ、好ましく４ｅ＋０４〜６ｅ＋０５ｄｙｎ／ｃｍとしてある。
上記ウレタン系粘着剤膜の積層貼り合わせ構造の積層数は、通常２層とされるが、３層以上とするも可能である。
【００１３】
本発明に係る上記の粘着剤式鑑識用シートを製造するには、（１）支持フィルム１１上にウレタン粘着剤の溶剤溶液を塗布乾燥することによりウレタン粘着剤膜を形成し、（２）他方、剥離性のキャスティグキャリシート上にウレタン粘着剤の溶剤溶液を塗布乾燥してウレタン粘着剤膜を形成し、このウレタン粘着剤膜を台紙の離型性プラスチックフィルム面２２に転写し、（３）この台紙上のウレタン粘着剤膜と前記支持フィルム１１上のウレタン粘着剤膜とを貼り合わせ、これにて、これにて粘着剤式鑑識用シートの製造を終了することができる。
上記の（１）及び（２）で形成されたウレタン粘着剤膜の厚みは薄く、従って製膜時の塗布ウレタン粘着剤溶液からの溶剤の蒸発を表面と内部とでほぼ同時を行わせることができ、共にクレータのない極平坦な外観形状にできるから、前記貼り合わせによるウレタン粘着剤積層にもその極平坦性を維持させ得、（２）のキャスティグの表面平滑性を充分に保有させることができる。
【００１４】
本発明に係る上記の粘着剤式鑑識用シートは、支持フィルム１１上にウレタン粘着剤の溶剤溶液を塗布乾燥することによりウレタン粘着剤膜を形成することを数回繰返し、この積層貼り合わせ構造のウレタン系粘着剤層に台紙の離型性プラスチックフィルム面２２に貼り付けることにより製造することも可能であり、この場合も、ウレタン粘着剤膜の厚みを薄くして製膜時の塗布ウレタン粘着剤溶液からの溶剤の蒸発を表面と内部とでほぼ同時を行わせることができるから、ウレタン粘着剤積層の表面をクレータのない平滑面にできる。
【００１５】
本発明に係る粘着剤式鑑識用シートを使用して指紋を採取するには、指紋採取対象面にアルミナ粉末またはストンパウダ−やカ−ボン粉末をダスタ−刷毛等で少しづつ撒布し、穂先で軽く払うようにして、指紋隆線の部分だけに粉を付着させ指紋を浮き上げていく。次に、前記ウレタン粘着シート１を台紙２から剥離し、ウレタン系粘着剤層面１２を指紋採取面に密接に当接し、更に剥離して前記の浮き上げ指紋をウレタン系粘着剤層面１２に転写させる。而るのち、この指紋転写粘着シートを台紙２の離型性プラスチックフィルム面２２に再貼着し、台紙表面の記入欄に所定事項を記入し、これにて採取を終了する。
【００１６】
而るに、ウレタン系粘着剤層面１２の平滑性のために浮き上がり指紋を高精度で転写採取できる。また、浮き上がり指紋がアルミナ粉末やストンパウダ−（白色）またはカ−ボン粉末（黒色）により視覚化されており、台紙の離型性プラスチックフィルム面をこれらそれぞれの色彩とコントラストの強い黒色または白色としてあり、かつウレタン系粘着剤層及び支持フィルムが共に透明であるから、浮き上げ指紋を転写したウレタン粘着シートを台紙に再貼着した状態で指紋を明確に鑑識できる。
【００１７】
上記ウレタン系粘着剤層においては、アクリル系粘着剤等の粘着シートとして汎用されている粘着剤に較べて貯蔵弾性率が小であり、ドアノブ等の面変化の急峻な指紋採取対象面にウレタン粘着シートを密接に当接しても、ウレタン系粘着剤層の曲げ歪みに伴う伸びで生じる薄肉化を軽度にとどめ得、凹凸の急峻な採取対象面でもウレタン系粘着剤量を充分に保有させて指紋採取を満足に行い得る。
【００１８】
本発明に係る鑑識用粘着シートにおいて、ウレタン系粘着剤層の厚みを８０〜１００μmとした理由は、８０μm未満では粘着力が低くなり過ぎ上記の浮き上げ指紋の転写を満足に行い難く、１０００μmを越えると粘着力が高くなり過ぎ、指紋採取対象面の如何によっては壁面の塗装剥げ等の原状破損が避けられないからである。また、粘着剤層の粘着力を２Ｎ/20mm以下とした理由は、２Ｎ/20mmを越えると粘着力が高くなり過ぎ、指紋採取対象面の如何によっては壁面の塗装剥げ等の原状破損が生じるからである。更に、貯蔵弾性率を３ｅ＋０４〜８ｅ＋０５ｄｙｎ／ｃｍにした理由は、３ｅ＋０４ｄｙｎ／ｃｍ未満ではドアノブ等の面変化の急峻な指紋採取対象面の場合、ウレタン系粘着剤層の曲げ歪みに伴う伸びで生じる薄肉化のために上記の厚みでは指紋採取を満足に行い難く、ウレタン系粘着剤の厚みをそれ以上厚くすると粘着剤の加圧による流動で指紋を正確に転写し難くなり、８ｅ＋０５ｄｙｎ／ｃｍを越えるとウレタン系ではかかる高弾性の達成が困難であるからである。
【００１９】
本発明において、ウレタン系粘着剤には、ポリオ−ルにプロピレングリコ−ルを、ジイソシアネ−トに脂肪族ウレタンまたは脂環族ウレタンを有するイソシヤネ−ト化合物を使用したポリエ−テル−ポリウレタン系を使用することが好ましく、脂肪族ウレタンとしては、ＨＤＩ（ヘキサメチレンジイソシアネ−ト）、ＸＤＩ（キシリレンジイソシアネ−ト）、水添ＭＤＩ〔４，４’−メチレンビス（シクロヘキシルイソシアネ−ト）〕等を挙げることができ、脂環族ウレタンとしては、ＩＰＤＩ（イソホロンジイソシアネ−ト）、Ｈ６ＸＤＩ〔１，３−ビス（イソシアナトメチル）シクロヘキサン〕等を挙げることができる。更に、ＸＤＩ系、ＨＤＩ系アダクトタイプ、トリマ−タイプ等の架橋剤を分散させて熱硬化型とすることもできる。
【００２０】
上記の実施例では、潜在的に付着している指紋の視覚化を、指紋隆線に沿って開口された汗腺から分泌されて対象面に付着した汗に微粉末を付着させる方法を使用しているが、分泌物中のアミノ酸に反応して発色するニンヒドリン溶液を噴霧する方法、分泌物中の尿素に反応して発色す硝酸銀溶液を噴霧する方法等を使用することもできる。
【００２１】
上記ウレタン粘着シートの透明支持フィルムには、ポリエチレンテレフタレ−ト、ポリブチレンテレフタレ−ト、ポリエチレンナフタレ−ト等のポリエステルフィルム、ポリエチレン、ポリプロピレン等のポリオレフィンフィルム、セルロ−ズジアセテ−ト、セルロ−ズトリアセテ−ト等のセルロ−ス系樹脂フィルム、ポリカ−ボネ−トフィルム等の延伸または無延伸フィルムを使用でき、就中、耐熱性、機械的強度、寸法安定性の何れにも優れた二軸延伸ポリエステルフィルムが好ましく、特にポリエチレンテレフタレ−トフィルムが耐熱性、透明性、経済性の観点より最適である。この支持フィルムの粘着剤塗工面には、投錨力を向上させるために必要に応じコロナ処理等の接着性向上処理を施すことができる。この支持フィルムの厚みは柔軟性を満たせば特に限定されず、好ましい厚みは一般に５０〜１２５μmである。
【００２２】
上記台紙の裏面に接着される白色または黒色の離型性フィルムには、臨界表面張力が３５ｄｙｎ／ｃｍ以下のものがものが使用され、背面処理剤で剥離処理したポリスチレン、ポリエチレン、ポリビニルブチラ−ル、ポリプロピレン、ポリ弗化ビニル、ポリ弗化エチル、等のフィルムを使用できる。この離型性フィルムとしては、延伸または無延伸の何れのフィルムも使用できるが、フィルム強度上二軸延伸したフィルムを使用することが好ましく、厚みは２５〜１２５μm、特に取扱性や加工性の点から２５〜１００μmのものを使用することが好ましい。
【００２３】
本発明に係る鑑識用粘着シートは前記した指紋採取以外に、堅い床やアスファルト面に付着した土ほこりが作る履物の底やタイヤ接地面の紋様の採取・保管にも使用できる。
【００２４】
【実施例】
以下の実施例及び比較例の何れにおいても、支持フィルムには厚み７５μmの透明ポリエチテンテレフタレ−トフィルムを、台紙には臨界表面張力３５ｄｙｎ／ｃｍ、厚み５０μmの黒色プロピレン離型フィルムを接着した上質紙を、キャスティグキャリアシートにはシリコーン処理したエチテンテレフタレ−トシートを使用した。
【００２５】
〔実施例１〕
図１に示す構成であり、ポリオ−ルにプロピレングリコ−ルを使用し、イソシヤネ−ト化合物にＨＤＩ（ヘキサメチレンジイソシアネ−ト）を使用したポリエ−テル−ポリウレタン粘着剤の８５重量％トルエン溶液に架橋剤を９．５重量％添加したウレタン系粘着剤溶液を支持フィルム上に塗布し、１４０℃×５分の条件で硬化させて厚み５０μmのウレタン系粘着剤膜を形成した。
また、同じウレタン系粘着剤溶液をキャスティグキャリアシートに塗布し、同様の乾燥条件で硬化させて厚み５０μmのウレタン系粘着剤膜を形成し、このウレタン系粘着剤膜を台紙の離型フィルム層に転写した。
更に、支持フィルムと台紙とをウレタン系粘着剤膜面において１００℃でラミネートしてウレタン系粘着剤層厚さ１００μmの粘着剤式鑑識シートを得た。
【００２６】
〔実施例２〕
実施例１に対し、各ウレタン系粘着剤膜の厚さを１４０μmとしてウレタン系粘着剤層厚さ２８０μmの粘着剤式鑑識シートを得た。
【００２７】
〔比較例１〕
支持フィルム上に実施例１と同じウレタン系粘着剤溶液を使用し、同じ乾燥条件で硬化させて厚み２８０μmのウレタン系粘着剤単一層を形成し、このウレタン系粘着剤単一層に台紙を貼着した。
【００２８】
〔比較例２〕
アクリル系粘着剤の４０重量％トルエン溶液にアルキレ−ト化合物（硬化剤）を２重量％添加したアクリル系粘着剤溶液を支持フィルム上に塗布し、１１０℃×１０分の硬化条件で硬化させて厚み５０μmのアクリル系粘着剤層を形成した。
また、同じアクリル系粘着剤溶液をキャスティグキャリアシートに塗布し、同様の乾燥条件で硬化させて厚み５０μmのアクリル系粘着剤膜を形成し、このアクリル系粘着剤膜を台紙の離型フィルム層に転写した。
更に、支持フィルムと台紙とをアクリル系粘着剤膜面において１００℃でラミネートしてウレタン系粘着剤層厚さ１００μmの粘着剤式鑑識シートを得た。
【００２９】
〔比較例３〕
比較例２に対し、各アクリル系粘着剤膜の厚さを１４０μmとしてアクリル系粘着剤層厚さ２８０μmの粘着剤式鑑識シートを得た。
【００３０】
これら実施例及び比較例(各試料数は１０個)の指紋採取性、粘着力、貯蔵弾性率、粘着層の外観を評価したところ、表１の通りであった。
ただし、それらの測定・評価方法は次の通りとした。
〔粘着層の外観〕粘着層を乾燥硬化させた際、粘着層の外観が目視で均一と認められるものを○、クレータ状になっているものを×と評価した。
〔粘着力〕粘着シートをステンレス板に２ｋｇロ−ラの１往復で圧着し、圧着３０後に１８０°ピ−ル、引張り速度３００mm/minの条件で粘着力を測定した。
〔粘着剤層の貯蔵弾性率〕ＲｈｅｏｍｅｔｒｉｃＳｃｉｅｎｔｉｆｉｃ社のＡＲＥＳを使用して測定した。
〔指紋採取性Ａ〕急峻な面変化の金属対象面に指紋を付け、ストンパウダ−をダスタ−刷毛等で少しづつ撒布し、穂先で軽く払うようにして指紋を浮き上らせ、これを粘着シートに転写させ、指紋全体を鮮明に採取できたときを○、指紋の一部分を転写できなかったものを△と評価した。
〔指紋採取性Ｂ〕古い塗装対象面に指紋を付け、これに粘着シートを粘着・剥離したときに、塗装の剥離がなかったものを○、塗装の剥離があったものを×と評価した。
【００３１】
【表１】

【００３２】
【発明の効果】
本発明に係る粘着剤式鑑識用シートによれば、貯蔵弾性率が３ｅ＋０４〜８ｅ＋０５ｄｙｎ／ｃｍと高いウレタン系粘着剤を使用しているから、面変化の急峻な指紋採取対象面に当接しても粘着剤層の厚みをよく保持させて満足に指紋を転写させ得、また、ウレタン粘着剤層の厚みを８０〜１０００μmとし、粘着力を５Ｎ/20mm以下として粘着力を充分に低くしているから、指紋採取対象面の塗装剥げ等を確実に回避でき、更に、ウレタン系粘着剤層の表面を極平滑化しているから、高精度の転写を保証できる。従って、優れた指紋採取を保証できる。
特に、請求項２の粘着剤式鑑識用シートによれば、上記の優れた指紋採取を一回の転写で行うことができるから、採取作業の簡易化を図ることができる。
【図面の簡単な説明】
【図１】本発明に係る粘着剤式鑑識用シートを示す図面である。
【符号の説明】
１粘着シート
１１支持フィルム
１２ウレタン系粘着剤層
１２１ウレタン系粘着剤膜
２台紙[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure sensitive adhesive sheet used for collecting fingerprints, footprints, tire marks, and the like, and a method for producing the pressure sensitive adhesive sheet.
[0002]
[Prior art]
In criminal forensics, information such as potentially attached fingerprints and footprints must be visualized and collected, and the information must be objectively communicated to investigators, judges, and lawyers.
Traditionally, to collect fingerprints, since the secretions from the sweat gland openings of the fingerprint ridges adhere to the point where the finger of the hand touches, spread the alumina powder etc. little by little with a duster brush etc. In this way, a method has been traditionally used in which powder is attached to only the fingerprint ridges to lift the fingerprint and transfer the lifted fingerprint to gelatin paper.
[0003]
However, in the methods using these gelatin papers, when fingerprints attached to automobile frames or the like are collected in summer, the frames are often at a temperature of 70 ° C. or higher. Gelatin that softens and melts in the fluid flows and fingerprints cannot be collected.
Also, depending on the environmental temperature, after fingerprint collection, the ambient temperature rises and the fingerprint changes, and it is often impossible to provide for identification. Furthermore, fingerprinting near the heater is difficult even in winter. Furthermore, since the gelatinous material is hydrophilic, it is vulnerable to moisture and may not be used due to swelling in places containing moisture.
[0004]
Therefore, it has been proposed to use an acrylic adhesive sheet instead of the gelatin paper (Japanese Patent Laid-Open No. 3-80833).
However, with acrylic adhesives, when collecting fingerprints adhering to the unevenly raised surface, if the acrylic adhesive sheet is brought into close contact with the surface to be collected, the adhesive layer stretches at sharp surface changes such as corners. Thinning makes the amount of adhesive at that location insufficient, making accurate collection difficult.
On the other hand, when the pressure-sensitive adhesive layer is thickened, the adhesive strength is increased accordingly, and coupled with the original high adhesive strength of the acrylic pressure-sensitive adhesive, original damage such as peeling of the coating on the surface to be collected tends to occur.
[0005]
Therefore, in the present inventors, the urethane pressure-sensitive adhesive layer has a smaller storage elastic modulus than the acrylic pressure-sensitive adhesive layer, and the urethane pressure-sensitive adhesive sheet is closely attached to the surface where fingerprints are to be collected, such as a door knob. Even if it comes into contact, the thickness of the urethane-based adhesive layer can be reduced thinly due to the elongation due to bending strain, and even on the surface where the unevenness is sharp, the amount of urethane-based adhesive is sufficiently retained to satisfy fingerprint collection. Focusing on what can be done, it has already been proposed to use a urethane-based adhesive sheet as an identification sheet (Japanese Patent Application No. 11-218403).
[0006]
Furthermore, in the conventional fingerprint collecting method, the fingerprint trace transferred to gelatin paper or acrylic adhesive sheet is transferred again to the black backing paper to make the fingerprint base paper, which is stored and transferred. For this reason, it is necessary to perform the transfer twice, and handling is complicated.
In view of this, the present inventors pasted an adhesive sheet coated with a urethane-based adhesive on one side of a transparent support film on one side of a backing paper that had a different color from fingerprint traces visualized by fine powder distribution or chemical spraying. Prepare a collection sheet, and peel off the mount to transfer the visualized fingerprint trace to the urethane adhesive layer of the adhesive sheet, and then transfer the transfer adhesive sheet to the release treatment surface of the mount It has already been proposed to collect the fingerprint trace by re-attaching to the above (Japanese Patent Application No. 11-218403).
[0007]
[Problems to be solved by the invention]
However, it is necessary to increase the thickness of the pressure-sensitive adhesive layer to some extent in order to satisfactorily transfer the fingerprint trace that has been lifted by attaching aluminum powder or the like to the fingerprint ridges.
Therefore, the pressure-sensitive adhesive layer is usually formed by applying a pressure-sensitive adhesive solution diluted with a solvent, and solidifying (drying) the coating solution by evaporation of the solvent, and is dried and solidified from the surface side. As a result, the evaporation of the solvent becomes slower as a result of this, and when the coating thickness exceeds a certain thickness, after the dry coagulated skin film is formed on the surface, the solvent is evaporated from the adhesive solution inside, and the skin film is broken and the surface of the adhesive layer Appearance may be crater-like, and with the above urethane adhesive layer thickness required to transfer fingerprint traces satisfactorily, the adhesive layer surface becomes crater-like and it is difficult to transfer fingerprint traces with high accuracy. .
[0008]
An object of the present invention is to provide a pressure sensitive adhesive sheet that can be easily collected with a pressure sensitive adhesive sheet using a urethane adhesive having a low tack as a pressure sensitive adhesive and without damaging the surface to be fingerprinted. It is to provide a manufacturing method.
[0009]
[Means for Solving the Problems]
The adhesive-type forensic sheet according to the present invention is characterized in that, in the forensic sheet that is transferred and collected on the adhesive surface of the adhesive sheet, the adhesive layer has a laminated structure of urethane-based adhesive films. It can be implemented in the form of a discriminating sheet that is transferred and collected on the adhesive surface of the transparent adhesive sheet peeled off from the mount, and reattached to the mount. The rate is 3e + 04 to 8e + 05 dyn / cm, the thickness is 80 to 1000 μm, and the adhesive strength of the adhesive layer is 2 N / 20 mm or less.
[0010]
The method for producing a pressure sensitive adhesive sheet according to the present invention is a method for producing a forensic sheet that is transferred and collected on the adhesive surface of a transparent adhesive sheet peeled off from the mount, and reattached to the mount. Yes, transfer the formed urethane-based adhesive film to the release surface of the mount, form the same urethane-based adhesive coating film on the transparent base material, and place the above mount on the adhesive film surface on the coating film surface It is the structure characterized by bonding.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an adhesive-type identification sheet according to the present invention.
In FIG. 1, 1 is a urethane pressure-sensitive adhesive sheet, the support film 11 is transparent, and the urethane pressure-sensitive adhesive layer 12 has a laminated structure of urethane-based pressure-sensitive adhesive films 121 and 121. 2 is a mount, on the front of the paper sheet 21 on which the case number entry field, the collection date entry field, the collection property entry field, the collector name entry field, the witness name entry field, etc. are printed, A black or white plastic release film 22 is bonded or fused, and the urethane pressure-sensitive adhesive layer surface 12 of the urethane pressure-sensitive adhesive sheet 1 is bonded to the release plastic film surface 22.
[0012]
The urethane pressure-sensitive adhesive layer has a thickness of 80 to 1000 μm, preferably 100 to 300 μm, an adhesive strength of 2 N / 20 mm or less, preferably 1.8 N / 20 mm or less, and a storage elastic modulus of 3e + 04 to 8e + 05 dyn / cm, It is preferably 4e + 04 to 6e + 05 dyn / cm.
The number of laminated layers of the urethane pressure-sensitive adhesive film is usually 2 layers, but can be 3 layers or more.
[0013]
In order to produce the above-mentioned pressure-sensitive adhesive sheet according to the present invention, (1) a urethane pressure-sensitive adhesive film is formed by applying and drying a solvent solution of urethane pressure-sensitive adhesive on the support film 11, and (2) the other side. Then, a urethane adhesive solvent solution is applied and dried on a peelable casting sheet to form a urethane adhesive film, and this urethane adhesive film is transferred to the releasable plastic film surface 22 of the mount, (3) The urethane pressure-sensitive adhesive film on the mount and the urethane pressure-sensitive adhesive film on the support film 11 are bonded together, thereby completing the production of the pressure-sensitive adhesive sheet.
The thickness of the urethane pressure-sensitive adhesive film formed in the above (1) and (2) is thin, so that the evaporation of the solvent from the applied urethane pressure-sensitive adhesive solution during film formation can be performed almost simultaneously on the surface and inside. Both of them can be made into an extremely flat appearance shape without craters, so that the extremely flatness can be maintained even in the urethane pressure-sensitive adhesive lamination by the bonding, and the surface smoothness of the casting (2) can be sufficiently retained. it can.
[0014]
The above-mentioned pressure sensitive adhesive type identification sheet according to the present invention repeatedly forms a urethane pressure sensitive adhesive film on the support film 11 by applying and drying a solvent solution of the urethane pressure sensitive adhesive several times. It can also be manufactured by affixing to the releasable plastic film surface 22 of the mount on the urethane-based adhesive layer. In this case as well, the urethane adhesive film is applied at the time of film formation by reducing the thickness of the urethane adhesive film. Since the evaporation of the solvent from the solution can be performed almost simultaneously on the surface and inside, the surface of the urethane pressure-sensitive adhesive laminate can be made smooth without a crater.
[0015]
In order to collect fingerprints using the adhesive-type identification sheet according to the present invention, alumina powder or stone powder or carbon powder is applied to the surface where fingerprints are to be collected little by little with a duster brush, etc. As you pay, the powder sticks only to the part of the fingerprint ridge and lifts the fingerprint. Next, the urethane pressure-sensitive adhesive sheet 1 is peeled off from the mount 2, the urethane-based pressure-sensitive adhesive layer surface 12 is brought into close contact with the fingerprint collecting surface, and further peeled off to transfer the lifted fingerprint to the urethane-based pressure-sensitive adhesive layer surface 12. . After that, the fingerprint transfer adhesive sheet is reattached to the release plastic film surface 22 of the mount 2, and a predetermined item is entered in the entry field on the mount, thereby completing the sampling.
[0016]
Thus, because of the smoothness of the urethane-based pressure-sensitive adhesive layer surface 12, the raised fingerprint can be transferred and collected with high accuracy. Also, the raised fingerprint is visualized with alumina powder, stone powder (white) or carbon powder (black), and the releasable plastic film surface of the mount is black or white with strong color and contrast. In addition, since both the urethane pressure-sensitive adhesive layer and the support film are transparent, the fingerprint can be clearly identified in a state where the urethane pressure-sensitive adhesive sheet to which the lifted fingerprint is transferred is reattached to the mount.
[0017]
The urethane pressure-sensitive adhesive layer has a lower storage elastic modulus than the pressure-sensitive adhesives that are widely used as pressure-sensitive adhesive sheets such as acrylic pressure-sensitive adhesive, and has a urethane adhesive on the surface where fingerprints are to be collected, such as door knobs. Even if the sheet is in close contact, the thinning caused by the elongation due to the bending strain of the urethane-based adhesive layer can be kept to a slight level, and the surface of the object to be sampled with sharp irregularities can retain a sufficient amount of urethane-based adhesive for fingerprints. Sampling can be done satisfactorily.
[0018]
In the adhesive sheet for identification according to the present invention, the reason why the thickness of the urethane-based pressure-sensitive adhesive layer is 80 to 100 μm is that if the thickness is less than 80 μm, the adhesive strength is too low to transfer the raised fingerprint satisfactorily, and 1000 μm is used. If it exceeds, the adhesive strength becomes too high, and depending on the surface from which fingerprints are collected, original damage such as peeling of the wall surface cannot be avoided. Also, the reason why the adhesive strength of the adhesive layer is 2N / 20mm or less is that if it exceeds 2N / 20mm, the adhesive strength becomes too high, and depending on the surface where fingerprints are collected, the original damage such as peeling of the wall surface may occur. It is. Furthermore, the reason why the storage elastic modulus is 3e + 04 to 8e + 05 dyn / cm is that if it is less than 3e + 04 dyn / cm, in the case of a fingerprint collection target surface such as a doorknob whose surface change is abrupt, it is thin due to elongation due to bending strain of the urethane-based adhesive layer It is difficult to obtain fingerprints satisfactorily with the above-mentioned thickness for the purpose of making it easier, and when the thickness of the urethane-based adhesive is increased further, it becomes difficult to accurately transfer the fingerprint due to the flow of the pressure of the adhesive, and when exceeding 8e + 05 dyn / cm This is because it is difficult to achieve such high elasticity in a urethane system.
[0019]
In the present invention, as the urethane-based pressure-sensitive adhesive, a polyether-polyurethane system using propylene glycol as a polyol and an isocyanate compound having an aliphatic urethane or an alicyclic urethane as a diisocyanate is used. As the aliphatic urethane, HDI (hexamethylene diisocyanate), XDI (xylylene diisocyanate), hydrogenated MDI [4,4′-methylenebis (cyclohexyl isocyanate)] Examples of the alicyclic urethane include IPDI (isophorone diisocyanate), H6XDI [1,3-bis (isocyanatomethyl) cyclohexane] and the like. Further, a thermosetting type can be obtained by dispersing a crosslinking agent such as an XDI type, an HDI type adduct type, or a trimmer type.
[0020]
In the above example, visualization of potentially attached fingerprints using a method of attaching fine powder to sweat that is secreted from sweat glands opened along the fingerprint ridge and attached to the target surface However, it is also possible to use a method of spraying a ninhydrin solution that develops color in response to amino acids in the secretion, a method of spraying a silver nitrate solution that develops color in response to urea in the secretion.
[0021]
The transparent support film of the urethane pressure-sensitive adhesive sheet includes polyethylene terephthalate, polybutylene terephthalate, polyester film such as polyethylene naphthalate, polyolefin film such as polyethylene and polypropylene, cellulose diacetate, cellulose Stretched or non-stretched films such as cellulose resin films such as zutriacetate and polycarbonate films can be used, and in particular, biaxial stretching with excellent heat resistance, mechanical strength, and dimensional stability A polyester film is preferable, and a polyethylene terephthalate film is particularly optimal from the viewpoints of heat resistance, transparency and economy. The adhesive coating surface of the support film can be subjected to an adhesive improvement treatment such as corona treatment as necessary in order to improve the anchoring force. The thickness of the support film is not particularly limited as long as it satisfies flexibility, and a preferable thickness is generally 50 to 125 μm.
[0022]
A white or black release film having a critical surface tension of 35 dyn / cm or less is used as the white or black release film adhered to the back surface of the mount, and polystyrene, polyethylene, and polyvinyl butyler which have been subjected to a release treatment with a back surface treatment agent. Films such as polyethylene, polypropylene, polyvinyl fluoride, and polyethyl fluoride can be used. As the releasable film, either a stretched film or a non-stretched film can be used, but it is preferable to use a biaxially stretched film in terms of film strength, and the thickness is 25 to 125 μm, particularly in terms of handleability and workability. To 25 to 100 μm are preferably used.
[0023]
In addition to collecting fingerprints as described above, the pressure-sensitive adhesive sheet for identification according to the present invention can also be used for collecting and storing patterns on footwear and tire contact surfaces created by dirt dust adhering to a hard floor or asphalt surface.
[0024]
【Example】
In any of the following examples and comparative examples, a transparent polyethylene terephthalate film having a thickness of 75 μm was adhered to the support film, and a black propylene release film having a critical surface tension of 35 dyn / cm and a thickness of 50 μm was adhered to the mount. The paper was a silicon treated ethene terephthalate sheet used as a casting carrier sheet.
[0025]
[Example 1]
85% by weight of a polyurethane-polyurethane adhesive having the structure shown in FIG. 1 and using propylene glycol as the polyol and HDI (hexamethylene diisocyanate) as the isocyanate compound. A urethane-based pressure-sensitive adhesive solution in which 9.5% by weight of a crosslinking agent was added to the solution was applied on a support film and cured under conditions of 140 ° C. × 5 minutes to form a urethane-based pressure-sensitive adhesive film having a thickness of 50 μm.
The same urethane-based adhesive solution is applied to a casting carrier sheet and cured under the same drying conditions to form a 50-μm-thick urethane-based adhesive film, and this urethane-based adhesive film is used as a release film layer for the mount. Transcribed.
Furthermore, the support film and the backing paper were laminated at 100 ° C. on the urethane adhesive film surface to obtain an adhesive-type identification sheet having a urethane adhesive layer thickness of 100 μm.
[0026]
[Example 2]
For Example 1, a pressure sensitive adhesive sheet having a urethane pressure sensitive adhesive layer thickness of 280 μm was obtained with the thickness of each urethane pressure sensitive adhesive film being 140 μm.
[0027]
[Comparative Example 1]
Use the same urethane adhesive solution as in Example 1 on the support film and cure it under the same drying conditions to form a urethane adhesive single layer with a thickness of 280 μm. Adhere the backing to this urethane adhesive single layer did.
[0028]
[Comparative Example 2]
An acrylic pressure-sensitive adhesive solution obtained by adding 2% by weight of an alkylate compound (curing agent) to a 40% by weight toluene solution of an acrylic pressure-sensitive adhesive is applied onto a support film and cured under curing conditions of 110 ° C. × 10 minutes. An acrylic pressure-sensitive adhesive layer having a thickness of 50 μm was formed.
Also, the same acrylic adhesive solution is applied to a casting carrier sheet and cured under the same drying conditions to form an acrylic adhesive film having a thickness of 50 μm, and this acrylic adhesive film is used as a release film layer of the mount. Transcribed.
Furthermore, the support film and the backing paper were laminated at 100 ° C. on the surface of the acrylic pressure-sensitive adhesive film to obtain a pressure-sensitive adhesive sheet having a urethane pressure-sensitive adhesive layer thickness of 100 μm.
[0029]
[Comparative Example 3]
For Comparative Example 2, an acrylic adhesive sheet having an acrylic adhesive layer thickness of 280 μm was obtained with each acrylic adhesive film having a thickness of 140 μm.
[0030]
Table 1 shows the results of evaluating the fingerprint collecting property, adhesive strength, storage elastic modulus, and appearance of the adhesive layer of these examples and comparative examples (each sample number is 10).
However, the measurement / evaluation methods were as follows.
[Appearance of the pressure-sensitive adhesive layer] When the pressure-sensitive adhesive layer was dried and cured, the case where the appearance of the pressure-sensitive adhesive layer was visually confirmed to be uniform was evaluated as ◯, and the case where it was crater-like was evaluated as ×.
[Adhesive strength] The adhesive sheet was pressure-bonded to a stainless steel plate by one reciprocation of a 2 kg roller, and the pressure-sensitive adhesive strength was measured after the pressure bonding 30 under the conditions of a 180 ° peel and a pulling speed of 300 mm / min.
[Storage Elastic Modulus of Adhesive Layer] Measured using ARES of Rheometric Scientific.
[Fingerprint collection A] A fingerprint is attached to the surface of a metal subject with a steep surface change, and a stone powder is applied little by little with a duster brush. When the whole fingerprint was clearly collected, it was evaluated as ○, and when a part of the fingerprint could not be transferred, it was evaluated as Δ.
[Fingerprint collecting property B] Fingerprints were attached to an old surface to be painted, and when an adhesive sheet was adhered / peeled, it was evaluated as ◯ when the paint was not peeled off, and x when the paint was peeled off.
[0031]
[Table 1]

[0032]
【The invention's effect】
According to the pressure sensitive adhesive type identification sheet according to the present invention, since a urethane pressure sensitive adhesive having a high storage elastic modulus of 3e + 04 to 8e + 05 dyn / cm is used, even if it comes into contact with the surface of the fingerprint collection target with a sharp surface change. Since the thickness of the pressure-sensitive adhesive layer can be maintained well and fingerprints can be transferred satisfactorily, the thickness of the urethane pressure-sensitive adhesive layer is set to 80 to 1000 μm, and the pressure-sensitive adhesive strength is set to 5 N / 20 mm or less to sufficiently reduce the pressure-sensitive adhesive force Further, it is possible to reliably avoid peeling off the surface of the fingerprint collection target surface, and furthermore, since the surface of the urethane-based adhesive layer is extremely smoothed, high-precision transfer can be guaranteed. Therefore, excellent fingerprint collection can be guaranteed.
In particular, according to the pressure sensitive adhesive type identification sheet of claim 2, since the above excellent fingerprint collection can be performed by one transfer, the collection operation can be simplified.
[Brief description of the drawings]
FIG. 1 is a view showing a pressure sensitive adhesive type identification sheet according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Adhesive sheet 11 Support film 12 Urethane type adhesive layer 121 Urethane type adhesive film 2 Mount

Claims

A pressure sensitive adhesive type identification sheet, wherein the pressure sensitive adhesive sheet is transferred and collected on the pressure sensitive adhesive surface, and the pressure sensitive adhesive layer has a laminated structure of urethane pressure sensitive adhesive films.

In the forensic sheet that is transferred and collected on the adhesive surface of the transparent adhesive sheet peeled off from the mount and the adhesive sheet is reattached to the mount, the adhesive layer has a laminated structure of urethane adhesive films. A pressure sensitive adhesive-type identification sheet.

The pressure-sensitive adhesive type identification sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has a storage elastic modulus of 3e + 04 to 8e + 05 dyn / cm and a thickness of 80 to 1000 µm.

The adhesive type insight sheet according to any one of claims 1 to 3, wherein the adhesive strength of the adhesive layer is 2 N / 20 mm or less.

This is a method for producing a discriminating sheet by transferring and collecting on the adhesive surface of the transparent adhesive sheet peeled off from the mount, and reattaching the adhesive sheet to the mount, and releasing the formed urethane-based adhesive film from the mount Production of a pressure sensitive adhesive sheet characterized by forming a urethane-based adhesive coating film on a transparent base material, and bonding the mount to the coating film surface on the adhesive film surface. Method.