JP2004101834A - Image display medium and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display medium which presents peculiar decorative effects such as a lame effect in combination with a color layer of an image, a pattern, or the like on a medium and to provide a manufacturing method therefor. <P>SOLUTION: With respect to the image display medium and the manufacturing method therefor, a relief hologram or a diffraction grating is formed over a color layer of a medium having at least the color layer, by a plurality of dots, and the relief hologram or the diffraction grating has a reflecting layer and has 0.0001 to 0.09mm<SP>2</SP>dot area, and a diffraction direction of a dot is different from that of at least one of the other dots being in its neighborhood, and the plurality of dots include dots different by areas or a dot density has a gradient. <P>COPYRIGHT: (C)2004,JPO

Description

こので、６個のＲ_１は夫々互いに独立して水素原子またはメチル基を表わし、Ｒ_２は炭素数が１〜１６個の炭化水素基を表わし、ＸおよびＹは直鎖状または分岐鎖状のアルキレン基を表わす。ｌ、ｍ、ｎ、ｏ及びｐの合計を１００とした場合に、ｌは２０〜９０、ｍは０〜８０、ｎは０〜５０、ｏ＋ｐは１０〜８０、ｐは０〜４０の整数である。
【００３０】
上記式（１）で表わされるウレタン変性アクリル系樹脂は、例えば、好ましい１例として、メタクリル酸メチル２０〜９０モルとメタクリル酸０〜５０モルと２−ヒドロキシエチルメタクリレート１０〜８０モル、Ｚとしてイソボルニルメタクリレート０〜８０モルとを共重合して得られるアクリル共重合体であって、該共重合体中に存在している水酸基にメタクリロイルオキシエチルイソシアネート（２−イソシアネートエチルメタクリレート）を反応させて得られる樹脂である。
【００３１】
従って、上記メタクリロイルオキシエチルイソシアネートが共重合体中に存在している全ての水酸基に反応している必要はなく、共重合体中の２−ヒドロキシエチルメタクリレート単位の水酸基の少なくとも１０モル％以上、好ましくは５０モル％以上がメタクリロイルオキシエチルイソシアネートと反応していればよい。上記の２−ヒドロキシエチルメタクリレートに代えて、又は併用して、Ｎ−メチロールアクリルアミド、Ｎ−メチロールメタクリルアミド、２−ヒドロキシエチルアクリレート、２−ヒドロキシエチルメタクリレート、２−ヒドロキシプロピルアクリレート、２−ヒドロキシプロピルメタクリレート、４−ヒドロキシブチルアクリレート、４−ヒドロキシブチルメタクリレート等の水酸基を有するモノマーも使用することができる。
【００３２】
以上の如く、水酸基含有アクリル系樹脂中に存在している水酸基を利用して、分子中に多数のメタクリロイル基を導入したウレタン変性アクリル系樹脂を主成分とする樹脂組成物によって、例えば、回析格子等を形成する場合には、硬化手段として紫外線や電子線等の電離放射線が使用でき、しかも高架橋密度でありながら柔軟性および耐熱性等に優れた回析格子等を形成することができる。
【００３３】
上記式（１）で表されるウレタン変性アクリル系樹脂は、前記共重合体を溶解可能な溶剤、例えば、トルエン、ケトン、セロソルブアセテート、ジメチルスルフォキサイド等の溶媒に溶解させ、この溶液を撹拌しながら、メタクリロイルオキシエチルイソシアネートを滴下及び反応させることにより、イソシアネート基がアクリル系樹脂の水酸基と反応してウレタン結合を生じ、該ウレタン結合を介して樹脂中にメタクリロイル基を導入することができる。この際使用するメタクリロイルオキシエチルイソシアネートの使用量は、アクリル系樹脂の水酸基とイソシアネート基との比率で水酸基１モル当たりイソシアネート基０．１〜５モル、好ましくは０．５〜３モルの範囲になる量である。なお、上記樹脂中の水酸基よりも当量以上のメタクリロイルオキシエチルイソシアネートを使用する場合には、該メタクリロイルオキシエチルイソシアネートは樹脂中のカルボキシル基とも反応して−ＣＯＮＨ−ＣＨ_２ＣＨ_２−の連結を生じることもあり得る。
【００３４】
上記式（１）におけるＺは、上記のウレタン変性アクリル系樹脂を改質するために導入することができ、例えばフェニル基、ナフチル基等の芳香族環或いはピリジン等の複素芳香族環を有するモノマー、（メタ）アクリロイル変性シリコーンオイル（樹脂）、ビニル変性シリコーンオイル（樹脂）等の重合性二重結合基を有するシリコーンオイル（樹脂）、ラウリル（メタ）アクリレート、ステアリル（メタ）アクリレート等の長鎖アルキル基を有するモノマー、γ‐（メタ）アルコキシプロピルトリメトキシシラン等の珪素含有基を有するモノマー、２‐（パーフルオロ‐７‐メチルオクチル）エチルアクリレート、ヘプタデカフロロデシル（メタ）アクリレート等のフッ素系含有基を有するモノマー等の離型性を付与するモノマー、イソボルニル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート、ジシクロペンタニル（メタ）アクリレート、ジシクロペンテニル（メタ）アクリレート、ＥＯ変性ジシクロペンテニル（メタ）アクリレート等の嵩高い構造を有するモノマー、アクリロイルモルフォリン、ビニルピロリドン或いはビニルカプロラクトン等の環状親水性基を有するモノマー等いずれも用いることができる。
【００３５】
以上の例は、前記一般式（１）において、全てのＲ_１及びＲ_２がメチル基であり、Ｘ及びＹがエチレン基である場合であるが、本発明は、これらに限定されず、６個のＲ_１は夫々独立して水素原子又はメチル基であってもよく、更にＲ_２の具体例としては、例えば、メチル基、エチル基、ｎ−又はｉｓｏ−プロピル基、ｎ−、ｉｓｏ−又はｔｅｒｔ−ブチル基、置換又は未置換のフェニル基、置換又は未置換のベンジル基等が挙げられ、Ｘ及びＹの具体例としては、エチレン基、プロピレン基、ジエチレン基、ジプロピレン基等が挙げられる。このようにして得られる本発明で使用するウレタン変性アクリル系樹脂の全体の分子量としては、ＧＰＣで測定した標準ポリスチレン換算の平均分子量が１万〜２０万、更に２〜４万であることがより好ましい。
【００３６】
更に、硬化後の電離放射線硬化樹脂層（レリーフ形成層１５）の柔軟性、粘度を調整するために、本発明の電離放射線硬化性樹脂には、通常の熱可塑性樹脂や、アクリル系およびその他の単官能または多官能のモノマー、オリゴマー等を包含させることができる。例えば、単官能ではテトラヒドロフルフリル（メタ）アクリレート等のモノ（メタ）アクリレート、２官能以上では、骨格構造で分類するとエポキシ変性ポリオール（メタ）アクリレート、ラクトン変性ポリオール（メタ）アクリレート等のポリオール（メタ）アクリレート、ポリエステル（メタ）アクリレート、エポキシ（メタ）アクリレート、ウレタン（メタ）アクリレート、その他ポリブタジエン系、イソシアヌール酸系、ヒダントイン系、メラミン系、リン酸系、イミド系、フォスファゼン系等の骨格を有するポリ（メタ）アクリレートであり、紫外線、電子線硬化性である様々なモノマー、オリゴマー、ポリマーが利用できる。
【００３７】
官能基数は、特に限定されるものではないが、官能基数が３より小さいと耐熱性が低下する傾向があり、レリーフ形成層１５の１部に傷が入ったり、レリーフ面が白濁する、また、２０以上では柔軟性が低下する傾向があるため、特に３〜２０官能のものが好ましい。
【００３８】
上記モノマー或いはオリゴマーは、複数を組み合わせて用いてもよい。その使用量は、上記ウレタン変性アクリル系樹脂１００質量部当たり、５〜９０質量部の範囲、好ましくは１０〜７０質量部の割合で使用する。モノマー或いはオリゴマーの使用量が上記範囲未満では、得られる電離放射線硬化樹脂層の強度、耐熱性、耐擦傷性、耐水性、耐薬品性、基材１１に対する密着性が十分とはいえず、一方、モノマー或いはオリゴマーの使用量が上記範囲を超えると表面のタックが高くなり、ブロッキングを引き起こしたり、レリーフホログラムや回折格子等のレリーフ複製時に版（プレススタンパー）に材料の一部が残って（当業者が版取られと呼ぶ現象）、反復したレリーフ複製性（エンボス性）が低下する等の点で好ましくない。
【００３９】
さらに、電離放射線硬化性樹脂層（レリーフ形成層１５）へレリーフを形成（複製）する際には、レリーフ形成層１５面へ表面に凹凸レリーフが形成されているスタンパ（金属版、又は樹脂版）を圧着して、該凹凸レリーフをレリーフ形成層１５へ形成（複製）する。この時に、スタンパがレリーフ形成層１５から容易に引き剥がせるように、予めレリーフ形成層１５へ離型剤を含有させてもよい。該離型剤としては、公知の離型剤が適用でき、例えば、ポリエチレンワックス、アミドワックス、テフロン（登録商標）パウダー等の固形ワックス、弗素系、リン酸エステル系の界面活性剤、シリコーン等であり、特に好ましくは、離型剤は変性シリコーンである。具体的には、変性シリコーンオイル側鎖型、変性シリコーンオイル両末端型、変性シリコーンオイル片末端型、変性シリコーンオイル側鎖両末端型、トリメチルシロキシケイ酸を含有するメチルポリシロキサン（シリコーンレジンと称されている）、シリコーングラフトアクリル樹脂、及びメチルフェニルシリコーンオイル等がある。
【００４０】
上記シリコーンオイルの中でも、反応性シリコーンオイルは、電離放射線で硬化時に樹脂と反応し結合して一体化する。従って、後にレリーフ凹凸が形成されたレリーフ形成層１５の表面にブリードアウト（滲み出る）しない。この特徴的な性能は、レリーフ形成層１５と、そのレリーフ表面に設けた反射層１７との密着性を著しく向上できる。上記離型剤の使用量は、電離放射線硬化性樹脂１００質量部当たり約０．１〜５０質量部の範囲、好ましくは約０．５〜１０質量部の範囲で使用する。離型剤の使用量が上記範囲未満では、プレススタンパーと電離放射線硬化樹脂層との剥離が不十分であり、プレススタンパーの汚染を防止することが困難である。一方、離型剤の使用量が上記範囲を超えると、組成物の塗工時にはじきが発生して塗膜面の面が荒れたり、基材又は反射層との密着性が悪くなったり、転写時にレリーフ形成層１５皮膜が破壊（膜強度が弱くなりすぎる）を引き起こすので好ましくない。
【００４１】
さらにまた、硬化後の電離放射線硬化樹脂層（レリーフ形成層１５）の、耐熱性、膜強度、及び反射層１７との密着性を向上させるために、本発明の電離放射線硬化樹脂には、予め有機金属カップリング剤を含有させてもよい。該有機金属カップリング剤としては、公知のシランカップリング剤、チタンカップリング剤、ジルコニウムカップリング剤、アルミニウムカップリング剤がある。
このような有機金属カップリング剤は、電離放射線硬化性樹脂１００質量部あたり、０．１〜１０質量部の範囲で使用することが好ましい。
【００４２】
上記の電離放射線硬化性樹脂は、レリーフを形成後に、電離放射線を照射して硬化（反応）させると電離放射線硬化樹脂（レリーフ形成層１５）となる。電離放射線としては、紫外線（ＵＶ）、可視光線、ガンマー線、Ｘ線、または電子線（ＥＢ）などが適用できるが、紫外線（ＵＶ）が好適である。電離放射線で硬化する電離放射線硬化性樹脂は、紫外線硬化の場合は光重合開始剤、及び／又は光重合促進剤を添加し、エネルギーの高い電子線硬化の場合は添加しないで良く、また、適正な触媒が存在すれば、熱エネルギーでも硬化できる。
【００４３】
（レリーフ形成層の開始剤）光重合開始剤としては、例えば、アセトフェノン類、ベンゾフェノン類、ミヒラーベンゾイルベンゾエート、αーアミロキシムエステル、テトラメチルメウラムモノサルファイド、チオキサントン類などが適用できる。また、必要に応じて、光増感剤、光重合促進剤を添加する。このような光重合開始剤、及び光増感剤の含有量は、前記ウレタン変性アクリル系樹脂１００質量部当たり約０．５〜１０質量部の範囲で使用することが好ましい。
【００４４】
本発明の電離放射線硬化性樹脂組成物には、上記の各成分に加えて、ハイドロキノン等のフェノール類、ベンゾキノン等のキノン類、フェノチアジン等、銅類等の重合防止剤を配合すると貯蔵安定性が向上する。更に、必要に応じて、促進剤、粘度調節剤、界面活性剤、消泡剤等の各種助剤を配合してもよい。また、スチレン・ブタジエンラバー等の高分子体を配合することも可能である。
【００４５】
前述したように、剥離層１３を設ける場合は、レリーフ形成層１５は電離放射線硬化樹脂からなり、剥離層１３は、電離放射線硬化性樹脂へ熱可塑性樹脂を含有させる。剥離層１３を設けない場合は、レリーフ形成層１５の電離放射線硬化性樹脂へ熱可塑性樹脂を含有させない。該熱可塑性樹脂としては、ポリエステル系樹脂、塩化ビニール‐酢酸ビニール共重合体が適用でき、少なくとも１種を用いる。この剥離層１３の厚さは、通常は０．１〜１０μｍ程度、好ましくは０．２〜５μｍである。
【００４６】
剥離層１３を設ける場合は、レリーフ形成層１５は電離放射線硬化樹脂からなり、剥離層１３は、基材との密着性を上げるため電離放射線硬化性樹脂へ熱可塑性樹脂を含有させ、その含有率は、剥離層組成物中の含有率で電離放射線硬化性樹脂が９０〜９９．９質量％、熱可塑性樹脂が０．１〜１０質量％とする。基材１１との密着力が不十分の場合は、転写箔状態での取扱い中に、レリーフ形成層１５が脱落したりドット間にバリが発生する恐れがある。一方、熱可塑性樹脂の使用量が上記範囲を超えると、基材１１との密着力が強過ぎて、サーマルヘッドでの転写時に転写しなかったり、ドットが欠けたりするので、好ましくない。このレリーフ形成層１５の厚さは、通常は０．１〜３０μｍ程度、好ましくは０．２〜５μｍである。
【００４７】
剥離層１３を設けない場合の転写箔は、レリーフ形成層１５の電離放射線硬化性樹脂へは熱可塑性樹脂を含有させない。この場合、レリーフ形成層１５の厚さは、通常は０．２〜３０μｍ程度、好ましくは０．５〜１０μｍである。
【００４８】
（転写箔の反射層）反射層１７は、ホログラム又は回折格子等のレリーフ構造を設けたレリーフ形成層１５面のレリーフへ反射層１７へ設けることにより、ホログラムの再生像及び／又は回折格子などが明瞭に視認できるようになる。該反射層１７として、光を反射する金属を用いると不透明タイプとなり、レリーフ形成層１５面と屈折率に差のある透明金属化合物を用いると透明タイプとなる。反射層１７としては、Ｃｒ、Ｔｉ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ａｇ、Ａｕ、Ｇｅ、Ａｌ、Ｍｇ、Ｓｂ、Ｐｂ、Ｐｄ、Ｃｄ、Ｂｉ、Ｓｎ、Ｓｅ、Ｉｎ、Ｇａ、Ｒｂ等の金属、及びその酸化物、硫化物、窒化物等の薄膜を単独又は複数を組み合わせてもよい。好ましい金属としてはアルミニウム、クロム、ニッケル、金、銀である。
【００４９】
また、透明タイプの反射層１７としては、レリーフ形成層１５面と屈折率に差のある透明金属化合物を用いる。その光学的な屈折率がレリーフ形成層のそれとは異なることにより、ほぼ無色透明な色相で、金属光沢が無いにもかかわらず、ホログラム等のレリーフを視認できる。該反射層１７の屈折率としては、レリーフ形成層１５面との屈折率の差が大きいほど効果があり、屈折率の差が０．３以上、好ましくは０．５以上、さらに好ましくは１．０以上である。例えば、ＺｎＳ、ＴｉＯ_２、Ａｌ_２Ｏ_３、Ｓｂ_２Ｏ_３、ＳｉＯ、ＴｉＯ、ＳｉＯ_２、ＩＴＯ、等が適用でき、好ましくは、ＩＴＯ、又は酸化スズで、屈折率はいずれも２．０であり、充分な屈折率の差を有している。また、屈折率が小さいものでは、ＬｉＦ、ＭｇＦ_２、ＡｌＦ_２などがある。なお、この透明とは、可視光が十分透過すれば良く、無色または有色で透明なものも含まれる。
【００５０】
上記の金属及び透明金属化合物の薄膜形成は、いずれも１０〜５０００ｎｍ程度、好ましくは２０〜２０００ｎｍの厚さになるよう、真空蒸着法、スパッタリング法、イオンプレーティング法などの真空薄膜法で得られる。反射層１７の厚さがこの範囲未満では、光がある程度透過して効果が減じ、また、その以上では、反射効果は変わらないので、コスト的に無駄である。ラメ効果の点では、金属薄膜が好ましい。
【００５１】
（転写箔の接着層）接着層１９は熱で溶融又は軟化して接着する熱接着型接着剤が適用でき、例えば、アイオノマー樹脂、酸変性ポリオレフィン系樹脂、エチレン‐（メタ）アクリル酸共重合体、エチレン‐（メタ）アクリル酸エステル共重合体、ポリエステル系樹脂、ポリアミド系樹脂、塩ビ系樹脂、酢ビ系樹脂、塩ビ酢ビ系樹脂、アクリル系・メタクリル系などの（メタ）アクリル系樹脂、アクリル酸エステル系樹脂、マレイン酸樹脂、ブチラール系樹脂、アルキッド樹脂、ポリエチレンオキサイド樹脂、フェノール系樹脂、ユリア樹脂、メラミン樹脂、メラミン‐アルキッド樹脂、セルロース系樹脂、ポリウレタン系樹脂、ポリビニールエーテル樹脂、シリコーン樹脂、ゴム系樹脂などが適用でき、これらの樹脂を単独または複数を組み合せて使用する。
【００５２】
これらの接着層１９の樹脂は、塩ビ系樹脂、酢ビ系樹脂、塩ビ酢ビ共重合体系樹脂、被転写材との親和性を考慮して選択される。一般的には、接着力などの点で、アクリル系樹脂、ブチラール系樹脂、ポリエステル系樹脂が好適である。接着層１７の厚さは、通常は０．０５〜１０μｍ程度、好ましくは０．１〜５μｍである。接着層１９の厚さは、この範囲未満では、被転写体との接着力が不足して脱落し、また、その以上では、接着効果は十分でその効果は変わらないのでコスト的に無駄であり、さらには、サーマルヘッドの熱を無駄に消費してしまう。さらにまた、接着層１９へは、必要に応じて、充填剤、可塑剤、着色剤、帯電防止剤などの添加剤を、適宜加えてもよい。充填剤としては、シリカ、炭酸カルシウムなどの体質顔料が適用できる。特に体質顔料の添加は、箔切れを良化させる。帯電防止剤としては、非イオン系界面活性剤、陰イオン系界面活性剤、陽イオン系界面活性剤などや、ポリアミドやアクリル酸誘導体などが適用できる。
【００５３】
（転写箔の耐熱保護層）さらにまた、基材の剥離層又はレリーフ形成層と反対面へ、耐熱保護層２１を設けてもよい。耐熱保護層２１は、耐熱性のある熱可塑性樹脂バインダーと、熱離型剤または滑剤のはたらきをする物質とを、基本的な構成成分とする。耐熱性のある熱可塑性樹脂バインダーとしては、広い範囲から選ぶことが出来るが、好適な例をあげれば、アクリル樹脂、ポリエステル樹脂、スチレン−マレイン酸共重合体、ポリイミド樹脂、ポリアミド樹脂、ポリアミドイミド樹脂、セルロースアセテートプロピオネート、セルロースアセテートブチレート、酢酸セルロース、フッ化ビニリデン樹脂、ナイロン、ポリビニルカルバゾール、塩化ゴム、環化ゴム及びポリビニルアルコールがある。これらの樹脂は、ガラス転移点が６０℃以上のもの、またはＯＨ基またはＣＯＯＨ基を有する熱可塑性樹脂にアミノ基を２個以上有する化合物またはジイソシアネートもしくはトリイソシアネートを加えて若干の架橋硬化を起させたものが好ましいことが経験的に知られている。
【００５４】
上記の熱可塑性樹脂に配合する、熱離型剤まはた滑剤は、ポリエチレンワックス、パラフィンワックスの様なワックス類、高級脂肪酸のアミド、エステル又は塩類、高級アルコール及びレシチン等のリン酸エステル類ような加熱により溶融してその作用をするものと、フッ素樹脂や無機物質の粉末のように、固体のままで役立つものとがある。尚、これらの滑剤又は熱離型剤に加えて、他の離型剤、例えば、フッ素含有樹脂の粉末、グアナミン樹脂の粉末及び木粉のいずれかを併用することも出来、この場合には更に高い効果が得られる。
【００５５】
耐熱保護層２１を形成する組成物は前記の熱可塑性樹脂バインダー１００質量部に対し、上記の滑剤又は熱離型剤の作用をする物質を１０〜１００質量部の割合で配合して形成する。基材への適用は、適宜の溶剤で練ってインキとし、一般のコーティング剤の塗布方法と同様に、例えばロールコーティング法、グラビアコーティング法，スクリーンコーティング法、ファウンテンコーティング法等のコーティング法により、基体のレリーフ形成層でない面に、固形分０．１〜４ｇ／ｍ^２程度により塗布し、乾燥することによって行えばよい。
【００５６】
基材シートと耐熱保護層２１の付着を確実にするために、予め基体１１上にプライマー層を設けてもよい。プライマー層には、帯電防止剤を配合して、帯電防止処理を施すことができる。更に、プライマー層は、適宜の溶剤を利用してインキ形態として塗布するが、プライマー層の樹脂を水分散性または水溶性とすることができる。溶剤が水であれば、乾燥によって気体となって排出されるが、大気の環境を汚染することもない。また、一般に水分散系の樹脂は、一旦製膜されると再溶解しにくく、さらにこの層に接して耐熱保護層２１を形成する場合にその溶剤におかされにくいため、安定した性能を発現することができる。
【００５７】
このように、耐熱保護層２１を有する転写箔とすることで、被転写体の対象が拡大し、又は転写（印字、プリント）速度の高速化に伴って、該転写箔の耐熱保護層２１面からサーマルヘッドによる加熱印字を行なうときに、この操作を十分な転写効率を得るために必要される高エネルギーの下で行なっても、基体とサーマルヘッドとが熱融着してしまう所謂スティッキングが発生することがない。
【００５８】
（転写箔の製造方法）次に、本発明に使用する転写箔リボンの製造方法について説明する。基材／剥離層／レリーフ形成層／反射層が、順次積層されている転写箔の製造方法において、（ａ）基材へ剥離層を設ける工程、（ｂ）該剥離層面へレリーフ形成層を設ける工程、（ｃ）該レリーフ形成層へレリーフを賦形する工程、（ｄ）該レリーフ及び剥離層へ電離放射線を照射する工程、（ｅ）レリーフ面へ反射層を設ける工程からなる転写箔リボンの製造方法である。本発明の転写箔１は、基材１１の一方の面へ、剥離層１３、レリーフ形成層１５、反射層１７、接着層１９を設けたものである。接着層１９は被転写体へ設けてもよく必須ではないが、通常、転写箔へ設けるので、ここでの説明は、接着層１９の形成も含めた形で説明する。
【００５９】
（ａ）基材１１へ剥離層１３を設ける工程、
基材１１の一方の面へ、剥離層１３、レリーフ形成層１５を設ける場合で、まず、基材１１の一方の面へ剥離層１３を設ける。前述したウレタン変性アクリル系樹脂の電離放射線硬化性樹脂に、必要に応じて、同じく前述した、単又は多官能のモノマーやオリゴマー、離型剤、有機金属カップリング剤、光開始剤などの各種添加剤を加えて、さらに基材との適切な密着を確保するために、熱可塑性樹脂を剥離層組成物中の含有率で０．１〜１０質量％を含有させて、有機溶媒へ溶解又は分散させて、電離放射線硬化性樹脂組成物（インキ）とする。
【００６０】
なお、電離放射線硬化性樹脂とは、電離放射線を照射しない硬化する前の前駆体であり、電離放射線硬化樹脂とは、電離放射線を照射して硬化した後の樹脂である。該電離放射線硬化性樹脂組成物（インキ）を、公知のコーティング法又は印刷法で塗布し乾燥する。コーティング法としては、例えば、ロールコート、リバースロールコート、トランスファーロールコート、グラビアコート、グラビアリバースコート、などが適用できる。印刷法としては、例えば、凹版印刷、孔版印刷、フレキソ印刷、樹脂凸版印刷、グラビ印刷、グラビアオフセット印刷などがある。
【００６１】
次に、（ｂ）該剥離層面１３へ、レリーフ形成層１５を設ける工程である。レリーフ形成層１５としては、前述したウレタン変性アクリル系樹脂の電離放射線硬化性樹脂に、必要に応じて、同じく前述した、単又は多官能のモノマーやオリゴマー、離型剤、有機金属カップリング剤、光開始剤などの各種添加剤を加えて、有機溶媒へ溶解又は分散させて、レリーフ形成層１５組成物（インキ）とする。該レリーフ形成層１５組成物（インキ）を、公知のコーティング法又は印刷法で塗布し乾燥する。コーティング法又は印刷法としては、剥離層の形成と同様な方法が適用できる。また、硬化前の該レリーフ形成層１５面でもタックがなく、フイルムをロール状に直接巻き取ることができて、加工上極めて都合がよい。
【００６２】
（ｃ）該レリーフ形成層１５へレリーフを賦形する工程、
上記のように、基材上に塗工したレリーフ形成層１５面へレリーフを賦形する。レリーフは、２次元または３次元画像を再生可能な表面凹凸パターン（光回折パターン）が形成されたものである。この表面凹凸パターンとしては、物体光と参照光との光の干渉による干渉縞の光の強度分布が凹凸模様で記録されたホログラムや回折格子が適用できる。ホログラムとしては、フレネルホログラム、フラウンホーファーホログラム、レンズレスフーリエ変換ホログラム、イメージホログラム等のレーザ再生ホログラム、及びレインボーホログラム等の白色光再生ホログラム、さらに、それらの原理を利用したカラーホログラム、コンピュータホログラム、ホログラムディスプレイ、マルチプレックスホログラム、ホログラフィックステレオグラム、ホログラフィック回折格子などがある。
【００６３】
（レリーフの形成）回折格子としては、ホログラム記録手段を利用したホログラフィック回折格子があげられ、その他、電子線描画装置等を用いて機械的に回折格子を作成することにより、計算に基づいて任意の回折光が得られる回折格子をあげることもでき、単一若しくは多重に記録しても、組み合わせて記録しても良い。
【００６４】
（レリーフのスタンパ）通常、賦形は、レリーフ形成層１５の表面に、レリーフが形成されているスタンパ（金属版、又は樹脂版）を圧着（所謂エンボス）をして、該レリーフをレリーフ形成層１５へ形成（複製）した後に、スタンパを剥離することで行う。レリーフを複製するスタンパは、マスターそのものも使用できるが、摩耗や損傷の恐れがあるため、アナログレコード等におけるのと同様、マスターに金属メッキまたは紫外線硬化樹脂を塗布し、紫外線を照射して硬化させて剥がす等の方法（当業者では２Ｐ法と呼ぶ）により、金属又は樹脂による複製を行ない、複製された型（スタンパ）を使用して商業的複製を行なう。
【００６５】
（レリーフの複製）商業的複製の方法は、金型又は樹脂型のスタンパを用いて、レリーフ形成層１５の表面へエンボスしてレリーフを複製した後に電離放射線を照射するか、又は、エンボス中に電離放射線を照射してからスタンパを剥離することでレリーフを複製する。この商業的な複製は、長尺状で行うことで連続な複製作業ができる。本発明では、前述したように、レリーフ形成層１５へ離型剤などの添加剤を含有させることで、例えば、回析格子等をエンボス加工する時でも、スタンパが汚染せず、スタンパがレリーフ形成層１５からの剥離性を良好にし、スタンパを長期間連続して使用（反復エンボス性）できる。
【００６６】
（ｄ）該レリーフ及び剥離層へ電離放射線を照射する工程、
レリーフ形成層１５の表面へ、スタンパでエンボス中、又はエンボス後に、若しくはエンボス中及びエンボス後に、電離放射線を照射して、電離放射線硬化性樹脂を硬化させる。該電離放射線としては、紫外線（ＵＶ）、可視光線、ガンマー線、Ｘ線、または電子線（ＥＢ）などが適用できるが、紫外線（ＵＶ）が好適である。
【００６７】
（ＵＶ照射）紫外線を照射する紫外線（ＵＶ）ランプは、高圧水銀ランプ、メタルハライドランプが適用でき、紫外線硬化性樹脂組成物に応じて、適宜波長を選択すれば良い。その照射量は、組成物の材質や量と、ＵＶランプの出力と、加工速度に応じて照射すれば良い。好ましくは、紫外線の波長は３００ｎｍ以下の領域を含まないものであり、３００ｎｍ以下、特に２５４ｎｍの波長を照射すると過度の架橋反応のためか基材と剥離層の適切な剥離が得られなくなる。そのため、高圧水銀灯を用いる場合でも３００ｎｍ以下の波長の光強度を３００〜４００ｎｍの光強度に対して９９％以上カットできるような波長選択性フィルターをつけて照射することで基材１１と剥離層１３との密着力が程よくできる。
転写箔状態での取扱いではレリーフ形成層１５が脱落せず、かつ、サーマルプリンタのサーマルヘッドによる転写では、高速でかつ低エネルギーで、微細な面積のドットや、近接したドットが欠けず、バリの発生もなく、正確なドットを転写できる。
【００６８】
（ｅ）レリーフ面へ反射層１７を設ける工程
反射層１７は、公知の真空蒸着法、スパッタリング法、イオンプレーティング法などの真空薄膜法で形成する。反射層１７面へ、接着層１９を設ける。接着層１９の形成は、前述の熱接着性の樹脂を溶媒へ分散または溶解した組成物（インキ）を、公知のコーティング法又は印刷法で塗布し乾燥する。コーティング法又は印刷法としては、剥離層の形成と同様な方法が適用できる。乾燥は必要に応じて、転写適性をよくするために、フィラーを添加したり、ブラッシングさせたりしてもよい。
【００６９】
また、剥離層１３を設けず、基材１１へ直接レリーフ形成層が設けられた構成の転写箔でもよく、該転写箔リボンの製造方法は、（ａ）基材へレリーフ形成層を設ける工程、それ以外は剥離層１３のある転写箔リボンの製造方法と同じである。ここでは、（ａ）の工程について説明し、それ以外は省略する。
【００７０】
（ａ）基材１１へレリーフ形成層１５を設ける工程、
レリーフ形成層１５は、剥離層を設けないようにした以外は、剥離層１３のある転写箔リボンの製造方法に述べたレリーフ形成層１５の形成と同様である。該組成物を溶媒へ分散または溶解した組成物（インキ）を、公知のコーティング法又は印刷法で塗布し乾燥する。コーティング法又は印刷法としては、剥離層の形成と同様な方法が適用できる。
【００７１】
（ドットの転写）以上に説明してきた、転写箔リボン、及びサーマルプリンタを用いて、転写（印字）した画像表示媒体について説明する。
図７は、本発明の１実施例を示す面積の異なるドットが混在し、ドット密度に勾配のある画像表示媒体である。
図８は、本発明の１実施例を示す画像と強調関係を有するような画像表示媒体である。
図９は、本発明の１実施例を示すドットの組合せからなる形状の画像表示媒体である。
図１０は、本発明の１実施例を示すドットあるいはドットの組合せからなる形状の画像表示媒体である。
本発明の画像表示媒体１０５は、少なくとも着色層を有する媒体上に、前記着色層に重ねて、レリーフホログラム又は回折格子のレリーフが形成された転写箔リボンを用いて、サーマルヘッドで複数のドットを転写したもので、該ドットの面積が０．０００１〜０．０９ｍｍ^２であり、あるドットの回折方向が少なくとも１つの近隣の他のドットと異なるようにすればよい。
ドット１０１の面積としては、０．０００１〜０．０９ｍｍ^２が適用できる。この範囲未満では回折効果が発現せず、この範囲以上では複数ドットの相乗効果が薄れてラメ効果が減少する。また、この範囲のドットはサーマルヘッドの発熱素子の大きさに該当し、転写される媒体によって使い分けてもよい。つまり０．００１６ｍｍ^２はカードプリンタなど比較的、高解像度の要求される６００ｄｐｉの、サーマルヘッドの１ドットの面積に該当し、０．０９ｍｍ^２は媒体が大きいポスタープリンタなどの１００ｄｐｉの、サーマルヘッドの１ドットの面積に該当する。また、サーマルプリント時に、ドットへの印字エネルギーを階調とし、１〜１００％の範囲で負荷することで、該プリンタの１ドットの面積より小さいドット面積を転写することができる。例えば、６００ｄｐｉのサーマルプリンタの１ドットは０．００１６ｍｍ^２であるが、ドットへ負荷する印字エネルギーを減ずることで、１ドットより小さな０．０００１ｍｍ^２の微細なドットを転写させることができる。
従来このような微細なドットを、サーマルヘッドで欠けることなく安定して、転写することができなかった。
【００７２】
図１では、例えば、布織模様の着色層の上に、同じ面積のドットを規則的に転写して構成したものである。該ドットのレリーフは回折格子であり、１つ１つのドットは、近隣ドットと光の回折する方向が異なっている。図１で図示したドットの縦、横、右上がり斜め、右下がり斜めは、レリーフの畝を表わし該畝の直角方向へ光が回折する。また、図７で図示したドットの波模様は、ホログラムの畝を表わし光を回折して立体像を再生する。該ドットの面積あるいはドットの組み合わせによる面積は０．０１〜１．０ｍｍ^２、その転写占有率は５〜４０％、より好ましくは１０〜３０％としたもので、媒体上の画像や模様などの着色層と相乗して、特に顕著なラメ効果を示す。驚くべくことに、金銀糸を織り込んだ実物のラメよりも、なおいっそうの意匠効果が認められた。個々のドットの面積もしくはドットの占有率はこの範囲が好ましく、この範囲未満では視認性が低下して効果が減じ、この範囲を超えるとキラキラ感が強過ぎて、着色層との相乗効果がなくなってしまう。
【００７３】
図７では、面積の異なるドットが混在し、さらに、ドット密度が勾配を有している。さらにまた、１つのドット内部に光の回折する方向が異なっている複数の部分からなっている。このように、面積、回折方向の異なるドットとしたり、また、ドット密度に勾配を持たせたりすることで、特異な意匠効果を奏する。回折方向の異なるレリーフを有する転写箔リボンは、レリーフを賦形するスタンパに、回折方向の異なるレリーフを設ければよい。回折方向の異なるレリーフは、公知のレーザ光による多重撮影法、又は部分的に回折方向の異なる多数の部分を電子線描画で構成することで容易に得られる。
【００７４】
図８では、着色層３の画像、文字、記号、イラスト、写真などあらゆる絵柄と協調させて、ドットを転写し形成したものである。複数のドットを並べて全体としてハート型をするように転写し形成したので、着色層３との絵柄とマッチして高い意匠性を醸し出している。
【００７５】
ドット自身は、例えば、矩形や円形などの任意の形状でよく、また、複数のドットからなるドットでもよく、例えば、ハート形、菱形、星形、三日月形、円形、矩形などの面積の異なる任意な形状とし、その大きさも自由に形成することができる。図９では、ドット形状の組み合わせを種々に変化させたもので、面積の異なる星形、三日月形、ハート形、三角形などの形状を例示している。図１０では、ドットあるいはドットを組合せた例を示し、図１０−Ａ〜Ｆなどのように、種々の形状、大きさを任意とすることができる。
【００７６】
【実施例】
まず、転写箔リボンを作製する。なお、例中の部または％は特に断りのない限り質量基準である。本発明で使用するウレタン変性アクリル系樹脂（電離放射線硬化性樹脂）の製造例を以下に示す。
冷却器、滴下ロートおよび温度計付きの２リットルの四つ口フラスコに、トルエン４０ｇおよびメチルエチルケトン（ＭＥＫ）４０ｇをアゾ系の開始剤とともに仕込み、２−ヒドロキシエチルメタクリレート（ＨＥＭＡ）２４．６ｇ、メチルメタクリレート（ＭＭＡ）７３．７ｇ、ジシクロペンテニルオキシエチルメタクリレート２４．６ｇ、トルエン２０ｇ、およびＭＥＫ２０ｇの混合液を滴下ロートを経て、約２時間かけて滴下させながら１００〜１１０℃の温度下で８時間反応させた後、室温まで冷却した。
これに、２−イソシアネートエチルメタクリレート（昭和電工製、カレンズＭＯＩ）２７．８ｇ、トルエン２０ｇおよびＭＥＫ２０ｇの混合液を加えて、ラウリン酸ジブチル錫を触媒として付加反応させた。反応生成物をＩＲ分析によりイソシアネート基の２２００ｃｍ−１の吸収ピークの消失を確認し反応を終了した。得られたウレタン変性アクリレート系樹脂の溶液は、不揮発分４１．０％、該樹脂のＧＰＣ（溶剤：ＴＨＦ）で測定した標準ポリスチレン換算の分子量は３万、ポリマー１分子中の二重結合の平均個数は１３．０モル％、であった。得られた電離放射線硬化性樹脂は、一般式（１）において、Ｚにジシクロペンテニルオキシエチルメタクリレート、Ｒ１及びＲ２に−ＣＨ３、Ｘ及びＹに−Ｃ２Ｈ４−を導入し、ｎが０である樹脂である。
【００７７】
次に、レリーフ形成層用組成物（インキ）の製造例を以下に示す。
下記の配合割合の組成物をメチルエチルケトン（ＭＥＫ）で希釈して組成物の固形分を５０％に調製し、レリーフ形成層用組成物（インキ）とした。
電離放射線硬化性樹脂　　　　　　　　　　　　　　１００部
シリコーン（トリメチルシロキシケイ酸含有メチルポリシロキサン、ＫＦ−７３
１２、信越化学工業社製、商品名）　　　　　　　　　　１部
多官能ウレタンアクリレート（紫光ＵＶ―１７００Ｂ、日本合成化学工業社製、
商品名）　　　　　　　　　　　　　　２５部
光重合開始剤（イルガキュア９０７、チバスペシャルティケミカルズ社製、商品
名）　　　　　　　　　　　　　　　　　　　　　　　　５部
【００７８】
次に、剥離層用組成物（インキ）の製造例を以下に示す。
下記の配合割合の組成物をメチルエチルケトン（ＭＥＫ）で希釈して組成物の固形分を５０％に調製し、剥離層用組成物（インキ）とした。
電離放射線硬化性樹脂　　　　　　　　　　　　　　　　　　　１００部
シリコーン（トリメチルシロキシケイ酸含有メチルポリシロキサン、ＫＦ−７
３１２、信越化学工業社製、商品名）　　　　　　　　　　　　　　　　　１部
多官能ウレタンアクリレート（紫光ＵＶ―１７００Ｂ、日本合成化学工業社製
、商品名）　　　　　　　　　　２５部
光重合開始剤、イルガキュア９０７
（チバスペシャルティケミカルズ社製、商品名）　　　　　　　　　５部
熱可塑性樹脂（ポリエステル樹脂、バイロン２９ＳＳ）
（東洋紡績社製、商品名）　　　　　　　　　　　　　　　　　　　２部
【００７９】
（転写箔リボンの製造例）
厚さ６μｍのポリエステルテレフタレートフイルム（Ｆ−５３、東レ社製、商品名）の易接着処理面上に、フィルム速度１００ｍ／分で剥離層用組成物（インキ）を、乾燥後の厚みが０．５μｍになるように、ロールコーターで塗工し８０℃で乾燥させて、剥離層１３を形成した。該剥離層１３面へ、フィルム速度５０ｍ／分でレリーフ形成層用組成物（インキ）を、乾燥後の厚みが０．５μｍになるように、グラビアリバースコーターで塗工し１００℃で乾燥させて、レリーフ形成層１５を形成し、得られたフイルムは常温ではべとつかず、巻取状態で保管や後加工ができる。
該レリーフ形成層１５面へスタンパを加圧（エンボス）してレリーフを賦形する。別途、電子線を用いて、回析方向が異なる一辺が５０μｍの正方形からなる回析格子を、隣接する正方形の回析方向と一致させないで敷き詰めるように描画したマスター回析格子を用いて作ったマスターレリーフから、２Ｐ法で複製したスタンパを複製装置のエンポスローラーに貼着して、１５０℃で相対するローラーと間で加熱プレス（エンボス）して、微細な凹凸パターンからなる回折格子のレリーフを賦形させた。賦形後直ちに、紫外線の出力窓をパイレックス（登録商標）ガラスとした高圧水銀灯で、波長が３００ｎｍ以下の領域をほとんどカットした紫外線を照射して硬化させた。該レリーフ面へ真空蒸着法によりアルミニウムを厚さ３０ｎｍに蒸着して、反射型の回折格子を形成した。該レリーフ面へ、塩化ビニル‐酢酸ビニル共重合体の接着剤をグラビアコートで塗工し１００℃で乾燥して、厚さが０．２μｍの接着層を形成して転写箔を得た。該転写箔を所定幅にスリットして、カセットへ装填して転写箔リボンを得た。
【００８０】
（実施例１）
以上で得た転写箔リボンを、一般的なサーマルプリンタ（３００ｄｐｉ）に装荷して、昇華転写型サーマルプリンタで形成した着色層上に転写して０．０１７ｍｍ^２のドットをした図１０−Ａの画像表示媒体を得た。
【００８１】
（実施例２〜４、比較例１〜２）
ドット面積及びドットパターンを、表１のようにした以外は、実施例１と同様にして、実施例２〜４、比較例１〜３の画像表示媒体を得た。
【００８２】
【表１】

【００８３】
（実施例５〜７）
ドット面積、ドットパターンを表２のように、した以外は、実施例１と同様にして、実施例５〜７の画像表示媒体を得た。
【００８４】
【表２】

【００８５】
得られた画像表示媒体は、ラメ効果、着色層識別性、ホログラム意匠性の度合で評価した。ラメ効果は画像表示媒体を目視で観察して、ラメ効果が認められるものを「有」とし、認められないものを「なし」とした。着色層識別性、ホログラム意匠性は目視で観察して、認められるものを合格とし「○」を、認められないものを不合格とし「×」とした。
【００８６】
評価結果は、表１〜２にの下欄に記載した。実施例１〜３、５〜７では転写部の一部又は全部にラメ効果が認められ、着色層識別性、ホログラム意匠性も問題なかった。また、実施例４ではラメ効果はやや低下するも実用上は充分であり、着色層識別性、ホログラム意匠性は問題なかった。比較例１、２では、ラメ効果が不充分であり、かつ、着色層識別性は若干、劣っていた。比較例３ではラメ効果が不充分であり、ホログラム意匠性も不充分であった。
【００８７】
【発明の効果】
以上のように、本発明の画像表示媒体によれば、媒体あるいは媒体上の画像や模様などの着色層と相乗して、ラメ効果などの特異な装飾効果を発現し、また、媒体上の模様や写真の輪郭を、ハートマークとしたり、グラデーションとしたり、ドットの組み合わせのより種々の形状にできて、高い意匠性が得られる。
さらに、本発明の画像表示媒体の製造方法によれば、汎用のサーマルプリンタで、多数の転写箔を必要とせず、最少回の転写作業で、バリや欠けのない微細なドットを極めて容易に転写することができる。また、個々の媒体へ可変ドットを転写でき、さらに、オンデマンドでリアルタイムで情報を転写することもできる。
【図面の簡単な説明】
【図１】本発明の１実施例を示す画像表示媒体の模式的な平面図及び断面図である。
【図２】本発明の１実施例を示す画像表示媒体の模式的な断面図である。
【図３】本発明の１実施例を示す画像表示媒体の模式的な断面図である。
【図４】本発明の１実施例を示す転写箔の模式的な断面図である。
【図５】本発明の１実施例を示す転写箔の模式的な断面図である。
【図６】本発明の１実施例を示す転写箔の模式的な断面図である。
【図７】本発明の１実施例を示す面積の異なるドットが混在し、ドット密度に勾配のある画像表示媒体である。
【図８】本発明の１実施例を示す画像と強調関係を有するような画像表示媒体である。
【図９】本発明の１実施例を示すドットの組合せからなる形状の画像表示媒体である。
【図１０】本発明の１実施例を示すドットあるいはドットの組合せからなる形状の画像表示媒体である。
【符号の説明】
１　転写箔
１１　基材
１３　剥離層
１５　レリーフ形成層
１７　反射層
１９　接着層
２１　耐熱保護層
１００　媒体
１０１ドット
１０３、１０３Ａ、１０３Ｂ　着色層
１０５　画像表示媒体[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image display medium, and more particularly, to an image display medium exhibiting a lame effect by transferring a plurality of dots by a thermal head using a transfer foil, and a method of manufacturing the same.
[0002]
[Prior art]
(Overview of technology, background) Conventionally, transfer foils having a relief structure such as holograms and diffraction gratings can express unique decorative images and three-dimensional images, and these holograms and diffraction gratings require advanced manufacturing techniques. Since it cannot be easily manufactured, it is used as a forgery prevention. For example, credit cards, ID cards, cards such as prepaid cards, and paper tickets such as gift certificates, checks, bills, stock certificates, admission tickets, various certificates, etc., which cannot be reproduced by color copying, are used. ing. Furthermore, due to its unique design, it is often used for packaging materials, books, pamphlets, POPs, and the like.
As a means for attaching such a relief structure such as a hologram or a diffraction grating to an article, a method of performing transfer printing using a transfer foil is known. The transfer foil is formed by sequentially laminating a release layer, a relief forming layer in which a pattern such as a hologram or a diffraction grating is formed, a reflective layer, and an adhesive layer on a base material. As a method for transferring and printing the transfer foil, hot stamping (also called foil stamping) or heat transfer using a heating roll is generally used. In the heat transfer, a transfer foil is arranged between a heated stamp or roll of metal and a transfer object, and the transfer foil is pressed against the transfer object by the stamp or roll, and then the substrate is peeled off. However, in the transfer method using a hot stamp or a heating roll, there is a problem that it is extremely difficult to transfer a dot having a small area of several mm square or less or a close dot. Etching can be used as a means for forming such a fine pattern. However, there is a problem in that the number of steps is large, and time and cost are required.
[0003]
(Prior art) In recent years, a thermal printer using a thermal head capable of easily expressing fine dots and adjacent dots by transfer has been put on the market, and a hot-melt type or dye sublimation transfer type ink ribbon has been used. Is coming. A method of transferring dots in the form of dots using the thermal head is disclosed (for example, see Patent Document 1). However, the present invention shows how difficult it is to express an extremely fine pattern because the dot area is limited to a certain size or more. Also, with the conventional transfer foil, the printing speed is extremely slow because the thermal sensitivity in instantaneous heating of the thermal head is low, and the dots transferred to the transfer target are missing, and the foil coating between the dots remains. Further, there is a drawback that burrs are generated.
Furthermore, a method is disclosed in which a plurality of transfer foils having different diffraction directions are used to transfer the transfer foils in multiple layers so that the transfer foils are glittered (for example, see Patent Document 2). However, a plurality of transfer foils are required, a plurality of transfer operations must be performed, and the transfer of fine dots without burrs and chips is extremely difficult with conventional transfer foils. .
[0004]
[Patent Document 1]
JP-A-11-227368
[Patent Document 2]
JP-A-2001-315472
[0005]
[Problems to be solved by the invention]
Therefore, the present invention has been made to solve such a problem. The purpose is to transfer a relief hologram or a diffraction grating with a plurality of fine dots to act in synergy with a colored layer such as an image or a pattern on the medium, and an image display medium that exhibits a unique decorative effect such as a lame effect. And a method for producing the same.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, an image display medium according to the invention of claim 1 is an image display medium in which a relief hologram or a diffraction grating is formed by a plurality of dots on a medium having at least a colored layer so as to overlap the colored layer. In the medium, the area of the dot is 0.0001 to 0.09 mm. ² Wherein the relief hologram or the diffraction grating has a reflective layer, and the diffraction direction of one dot is different from that of at least one other neighboring dot. ADVANTAGE OF THE INVENTION According to this invention, the image display medium which expresses a special decoration effect synergistically with the coloring layer, such as an image and a pattern on a medium, is provided.
In the image display medium according to the second aspect of the present invention, the plurality of dots may have different dot densities such that dots having different areas are mixed. Has a gradient. According to the present invention, the outline of a pattern or a photograph on a medium is formed as a heart mark, a gradation, or in various shapes depending on the arrangement or combination of dots, thereby exhibiting a highly designed lame effect. An image display medium is provided.
The method for producing an image display medium according to claim 4, wherein the ionizing radiation is substantially the same as the ionizing radiation-curable resin of the substrate and the relief forming layer, at least on the medium having the coloring layer, superimposed on the coloring layer. By using a transfer foil ribbon in which a release layer made of a cured resin and a thermoplastic resin, a relief formed layer made of an ionizing radiation-cured resin on which a relief hologram or a diffraction grating relief is formed, a reflective layer, and an adhesive layer are sequentially laminated. In the method for manufacturing an image display medium in which a plurality of dots are transferred by a thermal head, the area of the dots is 0.0001 to 0.09 mm. ² Where the diffraction direction of a certain dot is different from that of at least one neighboring dot. ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the image display medium which expresses a special decoration effect, such as a lame effect, synergistically with the coloring layer, such as an image and a pattern, on a medium is provided.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic plan view and a sectional view of an image display medium showing one embodiment of the present invention.
FIG. 2 is a schematic sectional view of an image display medium showing one embodiment of the present invention.
FIG. 3 is a schematic sectional view of an image display medium showing one embodiment of the present invention.
(Overall Configuration) FIG. 1 shows an embodiment of the image display medium of the present invention, FIG. 1 (A) is a plan view, and FIG. 1 (B) is a cross-sectional view taken along line AA. In the image display medium 105, a coloring layer 103 is provided on one surface of the medium 100, and a plurality of dots 101 are provided on the coloring layer 103. The coloring layer 103 and the dots 101 may be on at least one side, and may be only the other side or both sides.
(Image Display Medium) The position of the dot 101 with respect to the coloring layer 103 may be above or below the coloring layer 103 or on both upper and lower surfaces when the coloring layer 103 is present. In FIG. 1, it is provided above the colored layer 103, and in FIG. 2, it is provided below the colored layer 103. Further, as shown in FIG. 3, the dots 101A may be provided on the coloring layer 103A, the coloring layer 103B may be further provided on the dots 101A, and the dots 101B may be provided on the coloring layer 103B. In this case, at least a part of the coloring layer 103B may be made transparent.
[0008]
The coloring layer 103 may be the same color over the entire surface, a plurality of partially different colors, or a white background. Further, it may be transparent or translucent, a colored medium, or a combination thereof. Alternatively, the coloring layer may be an image such as a character, a symbol, a photograph, an illustration, a pattern, or a combination thereof. In particular, it is preferable that images such as characters, symbols, photographs, illustrations, and patterns have a certain relationship with the plurality of dots of the present invention because the design is further enhanced. The colored layer 103A in FIG. 3 illustrates different colors or different images such as characters, symbols, photographs, illustrations, and patterns.
[0009]
The medium 100 only needs to have a printable or transferable surface on at least a part thereof and a thickness enough to maintain a certain flat state, and various materials can be applied according to the application. For example, in general, paper such as high quality paper, coated paper, paperboard cardboard, synthetic paper, polyester resin such as polyethylene terephthalate, polyamide resin such as nylon 6, polyolefin resin such as polyethylene, poly There are vinyl resins such as vinyl chloride, acrylic resins such as polymethacrylate, styrene resins such as polycarbonate and polystyrene, and cellulose films such as cellophane, etc., and those having high surface smoothness are desirable ( Beck smoothness meter 1000 seconds or more).
[0010]
(Medium) The medium is subjected to corona discharge treatment, plasma treatment, ozone treatment, flame treatment, and primer (also called an anchor coat, an adhesion promoter, and an easy adhesive) on the surface of the coloring layer 103 prior to the formation of the coloring layer 103. An easy adhesion treatment such as a treatment, a pre-heat treatment, and a dust removal treatment may be performed. If necessary, additives such as a filler, a plasticizer, a coloring agent, and an antistatic agent may be added to the medium.
[0011]
(Coloring layer) As the coloring layer 103, an ink, paint, or coating liquid may be printed or applied by a known printing method, coating method, or the like, and may be dried as necessary. As the coating method, for example, roll coat, reverse roll coat, transfer roll coat, gravure coat, gravure reverse coat, kiss coat, comma coat, rod coat, blade coat, bar coat, wire bar coat, knife coat, squeeze coat, Air doctor coat, air knife coat, die coat, lip coat, curtain coat, flow coat, dip coat, spray coat, cast coat, impregnation coat and the like can be applied.
[0012]
As the printing method, for example, a basic printing method of lithographic printing, intaglio printing, letterpress printing, stencil printing, and an applied printing method thereof can be applied. Applied printing methods include flexographic printing, resin letterpress printing, gravure offset printing, octopus printing, inkjet printing, transfer printing using a transfer foil, transfer printing using a hot-melt or sublimation type ink ribbon, electrostatic printing, etc. it can. Techniques also include ultraviolet (UV) curing printing where the ink is cured with ultraviolet light, baking printing where the ink is cured at a high temperature, and waterless offset printing without using dampening water.
[0013]
The printing ink used for letterpress printing, planographic printing, intaglio printing, stencil printing, or ink jet printing contains at least a vehicle and a coloring agent, and the viscosity thereof is preferably 0.1 to 3000 poise. The colorant contains at least one of an inorganic pigment and an organic pigment. Some protective inks do not contain colorants (also called overprint inks, OP varnish, OP).
[0014]
As the vehicle, one or more of dry oil, synthetic resin, natural resin, fiber, and rubber derivative can be applied. Examples of the dried oil include linseed oil, cinnamon oil, eno oil, soybean oil, fish oil, dehydrated castor oil, styrenated oil, vinyltoluene oil, and maleic oil. Natural resins include wood rosin, polymerized rosin, lime cured rosin, zinc cured rosin, rosin ester, shellac and the like. Examples of the synthetic resin include a phenol resin, a modified alkyd resin, a polyamide resin, coal tar pitch, and stearin pitch. Examples of the fiber system include nitrocellulose, ethyl cellulose, cellulose acetate, and cellulose acetate propionate. Examples of rubber derivatives include cyclized rubber and chlorinated rubber.
[0015]
If necessary, additives such as a filler, a plasticizer, a dispersant, a lubricant, an antistatic agent, an antioxidant, and a fungicide may be appropriately added to the ink composition.
These compositions are dispersed and kneaded, and if necessary, the solid content and the viscosity are adjusted with a solvent to obtain an ink composition. The ink may be printed by the printing method described above, dried, and, if necessary, appropriately aged at a temperature of 30 ° C. to 70 ° C. or irradiated with ionizing radiation (ultraviolet rays, electron beams).
[0016]
(Printer) As a printer for forming (transferring) the dots 101, a thermal printer (also referred to as a thermal transfer printer) can be applied. The thermal printer is a thermal printer using a thermal transfer recording medium provided with a heat sublimable dye ink layer (referred to as an ink ribbon) or a thermal transfer recording medium provided with a heat-meltable ink layer (referred to as an ink ribbon). In the thermal printer, a thermal printing head (also referred to as a thermal head or a printer head) and a platen roller are opposed to each other, and an ink ribbon and a medium provided with an image receiving layer as necessary are sandwiched between these. These are pressed against the thermal head by a rotating platen roller and travel in accordance with the rotation. The ink layer of the ink ribbon and the transfer target face each other.
[0017]
(Thermal head) Then, a heating element corresponding to the image of the thermal head generates heat, and the ink in the selectively heated in-ribbon is transferred in a dot shape to the transfer receiving body, and a predetermined image is formed by thermal transfer recording ( Printing and printing). The printing method includes a serial method and a line method. In the serial method, the thermal head scans in a direction perpendicular to the traveling direction of the transfer target, and prints each line. In the line method, a line-type thermal head having a plurality of heating element groups in a row in a direction perpendicular to the running direction is used, and the line-type thermal head is fixed in the running direction of the transfer object, and a printing operation ( While the ink ribbon and the transfer receiving body run), only a predetermined heating element is heated to print an image over the entire surface in the width direction.
[0018]
Examples of the heating element include a laser heat mode thermal head, a photothermal recording head, and a thermal head. The laser heat mode thermal head irradiates a laser beam corresponding to an image signal from a laser light source to the ink ribbon via a transparent support, and the ink ribbon that has absorbed the laser generates heat, thereby covering the ink of the ink ribbon. An image is printed by transferring and transferring to a transfer body. The photothermal recording head has a two-layered structure of a photoconductive layer and a heat generating layer, which are made conductive by light irradiation and generates heat, or a photoconductive heat generating layer composed of one layer of a photoconductive heat generating layer, and is disposed so as to sandwich the photoconductive heat generating layer. The head is basically composed of a pair of electrode layers to which a predetermined voltage is applied. The light source irradiates a laser beam or the like from a light source according to an image signal, and a photoconductive portion of the light-irradiated portion is provided. An image is printed by causing the heat generating layer or the photoconductive heat generating layer in the heat generating layer to generate heat and transfer the ink of the ink ribbon to the transfer target.
[0019]
The most common thermal head prints an image by causing a dot-shaped heating element to generate heat in accordance with an image signal and transferring ink (a dye or a heat-meltable ink) of an ink ribbon to a transfer target. It is to print. In the present invention, any thermal head may be used, and a preferable resolution of the thermal head is a high-resolution type thermal head having a resolution of 100 dpi or more, and more preferably 300 dpi or more. Further, at the time of thermal printing, a dot area smaller than one dot area of the printer can be transferred by setting the printing energy to the dots as gradation and applying a load in the range of 1 to 100%. For example, one dot of a 600 dpi thermal printer is 0.0016 mm. ² However, by reducing the printing energy applied to the dots, 0.0001 mm smaller than 1 dot ² Can be transferred. As described above, the type of the thermal head is optimized according to the size of the medium to be transferred. Conventionally, various media have been studied for a medium in which fine dots are transferred (printed) with a thermal head using a transfer foil on which a relief hologram or a relief of a diffraction grating is formed. However, it was far from practical use due to poor transfer suitability. The present invention is an image display medium in which a transfer foil is transferred (printed) by a thermal head with a finer dot than ever before, and can be stably put into practical use.
[0020]
(Ink Ribbon) As the ink ribbon used in the present invention, a transfer foil in which a release layer, a relief forming layer, a reflective layer, and an adhesive layer are sequentially laminated on at least a substrate as necessary can be applied. The transfer foil is composed of a release layer / a relief hologram or an ionizing radiation-curable resin on which a relief of a diffraction grating is formed, the main component of which is substantially the same as the ionizing radiation-curable resin of the substrate / relief forming layer. Forming layer / reflective layer / adhesive layer, or substrate / relief forming layer / reflective layer / adhesive layer composed of ionizing radiation curable resin on which relief of relief hologram or diffraction grating is formed, transfer foil sequentially laminated it can.
[0021]
The transfer foil will be described in detail with reference to the drawings.
FIG. 4 is a schematic sectional view of a transfer foil showing one embodiment of the present invention.
FIG. 5 is a schematic sectional view of a transfer foil showing one embodiment of the present invention.
FIG. 6 is a schematic sectional view of a transfer foil showing one embodiment of the present invention.
(Transfer Foil) The transfer foil 1 used in the present invention is provided with a release layer 13, a relief forming layer 15, a reflective layer 17, and an adhesive layer 19 on one surface of a substrate 11. The adhesive layer 19 may be provided on the transfer object, but is not essential. However, since the adhesive layer 19 is usually provided on the transfer foil, the description will be made with the adhesive layer 19 provided. As will be described later, a protective layer 21 may be provided on the other surface of the substrate 11 shown in FIG. 6, and depending on the type of the substrate, the release layer 13 shown in FIG. May also have a release layer function.
[0022]
(Substrate of Transfer Foil) As the substrate 11, various materials can be applied depending on the intended use, as long as the substrate has heat resistance, mechanical strength, mechanical strength, solvent resistance and the like that withstand the heat of the thermal head. it can. For example, polyethylene terephthalate / polybutylene terephthalate / polyethylene naphthalate / polyethylene terephthalate / isophthalate copolymer / terephthalic acid / cyclohexanedimethanol / ethylene glycol copolymer / polyethylene terephthalate / polyethylene naphthalate Polyester resin such as co-extruded film, polyamide resin, vinyl resin such as polyvinyl chloride, acrylic resin, imide resin, engineering resin such as polyarylate, cellulose film such as polycarbonate and cellophane ,and so on.
[0023]
The base material may be a copolymer resin containing these resins as a main component, a mixture (including an alloy), or a laminate including a plurality of layers. The substrate may be a stretched film or an unstretched film, but is preferably a film stretched uniaxially or biaxially for the purpose of improving strength. The thickness of the substrate is generally about 2.5 to 50 μm, but is preferably 2.5 to 12 μm, and most preferably 4 to 6 μm. If the thickness is larger than this, heat transfer from the thermal head is poor, and it is difficult to transfer detailed dots as in the present invention. Below this, the mechanical strength is insufficient. The substrate is used as a film, sheet or board composed of at least one layer of these resins. Usually, a polyester film such as polyethylene terephthalate or polyethylene naphthalate is preferably used because of its good heat resistance and mechanical strength, and polyethylene terephthalate is most suitable. The base material is subjected to corona discharge treatment, plasma treatment, ozone treatment, flame treatment, primer (also referred to as anchor coat, adhesion promoter, and easy-adhesive) treatment, pre-heat treatment, and dust removal treatment prior to application. An easy adhesion treatment such as a vapor deposition treatment or an alkali treatment may be performed. If necessary, additives such as a filler, a plasticizer, a colorant, and an antistatic agent may be added.
[0024]
(Release Layer of Transfer Foil) A relief forming layer 15 is provided on the base material 11 via a release layer 13 as necessary. The release layer 13 mixes the thermoplastic resin with an ionizing radiation-curable resin as necessary, and cures with ionizing radiation, thereby adhering moderately to a substrate, and easily releasing when a thermal head is loaded with heat. Then, the image is transferred to a transfer target (medium), and fine dots can be printed.
[0025]
That is, in the case of the transfer foil, the relief forming layer does not fall off due to vibration or impact during the transfer and handling of the transfer foil and the loading operation to the printer, and the transfer can be easily peeled off from the base material during transfer printing. If the adhesive strength to the base material is insufficient, the relief forming layer will fall off due to vibration or impact during the transfer and handling of the transfer foil and the loading operation to the printer. Alternatively, burrs that leave a foil film between dots during transfer occur. On the other hand, if the content of the thermoplastic resin is too large, the adhesive force to the base material is too good, so that transfer cannot be performed without peeling off from the base material during transfer printing.
[0026]
When the release layer 13 is provided, the relief forming layer 15 is made of an ionizing radiation-curable resin, and the release layer 13 is made to contain a thermoplastic resin in the ionizing radiation-curable resin. The ionizing radiation-curable resin is 90 to 99.9% by mass, and the thermoplastic resin is 0.1 to 10% by mass. The ionizing radiation-curable resin used for the release layer 13 may be substantially the same as the ionizing radiation-curable resin of the relief forming layer 15. Here, “substantially” means that the basic skeleton and the reaction mechanism may be the same, and the substituents and the chain length may be different. Further, in the calculation of the content, a reactive monomer, a release agent, and the like added to and reacted with the ionizing radiation-curable resin are included in the amount of the ionizing radiation-curable resin, and the same applies hereinafter.
[0027]
When the release layer 13 is not provided, the relief forming layer 15 is made of an ionizing radiation curable resin and does not contain a thermoplastic resin. Further, by using the ionizing radiation-curable resin substantially the same as the ionizing radiation-curable resin of the relief forming layer 15 as the peeling layer 13, the peeling layer 13 and the relief forming layer 15 may be substantially one layer. .
[0028]
(Relief-forming layer of transfer foil) As the ionizing radiation-curable resin (relief-forming layer 15), for example, an epoxy-modified acrylate resin, a urethane-modified acrylate resin, an acrylic-modified polyester, or the like can be used. A urethane-modified acrylic resin represented by the following general formula is preferred.
[0029]
Embedded image

So, six R ₁ Each independently represents a hydrogen atom or a methyl group; ₂ Represents a hydrocarbon group having 1 to 16 carbon atoms, and X and Y each represent a linear or branched alkylene group. When the total of l, m, n, o, and p is 100, 1 is 20 to 90, m is 0 to 80, n is 0 to 50, o + p is 10 to 80, and p is an integer of 0 to 40. is there.
[0030]
The urethane-modified acrylic resin represented by the above formula (1) is preferably, for example, 20 to 90 mol of methyl methacrylate, 0 to 50 mol of methacrylic acid, 10 to 80 mol of 2-hydroxyethyl methacrylate, and Z as isoform. An acrylic copolymer obtained by copolymerizing 0 to 80 mol of bornyl methacrylate, wherein methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate) is reacted with a hydroxyl group present in the copolymer. The resulting resin.
[0031]
Therefore, the methacryloyloxyethyl isocyanate does not need to react with all the hydroxyl groups present in the copolymer, and is preferably at least 10 mol%, more preferably at least 10 mol% of the hydroxyl groups of the 2-hydroxyethyl methacrylate unit in the copolymer. It is sufficient that 50 mol% or more of the compound has reacted with methacryloyloxyethyl isocyanate. Instead of or in combination with the above 2-hydroxyethyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate And monomers having a hydroxyl group, such as 4-hydroxybutyl acrylate and 4-hydroxybutyl methacrylate.
[0032]
As described above, by utilizing a hydroxyl group present in a hydroxyl group-containing acrylic resin, a resin composition mainly containing a urethane-modified acrylic resin in which a large number of methacryloyl groups are introduced in a molecule, for example, diffraction When a lattice or the like is formed, ionizing radiation such as ultraviolet rays or an electron beam can be used as a curing means, and a diffraction grating or the like having high flexibility and excellent heat resistance can be formed while having a high crosslinking density.
[0033]
The urethane-modified acrylic resin represented by the above formula (1) is dissolved in a solvent capable of dissolving the copolymer, for example, a solvent such as toluene, ketone, cellosolve acetate, and dimethyl sulfoxide. By dropping and reacting methacryloyloxyethyl isocyanate with stirring, the isocyanate group reacts with the hydroxyl group of the acrylic resin to form a urethane bond, and the methacryloyl group can be introduced into the resin via the urethane bond. . The amount of methacryloyloxyethyl isocyanate used at this time is in the range of 0.1 to 5 mol, preferably 0.5 to 3 mol, of isocyanate group per 1 mol of hydroxyl group in a ratio of hydroxyl group to isocyanate group of the acrylic resin. Quantity. When methacryloyloxyethyl isocyanate is used in an amount equal to or more than the hydroxyl group in the resin, the methacryloyloxyethyl isocyanate also reacts with a carboxyl group in the resin to form -CONH-CH ₂ CH ₂ It is possible that a-connection may occur.
[0034]
Z in the above formula (1) can be introduced to modify the urethane-modified acrylic resin, for example, a monomer having an aromatic ring such as a phenyl group or a naphthyl group or a heteroaromatic ring such as pyridine , (Meth) acryloyl-modified silicone oil (resin), vinyl-modified silicone oil (resin), etc., silicone oil (resin) having a polymerizable double bond group, lauryl (meth) acrylate, long chain such as stearyl (meth) acrylate Monomers having an alkyl group, monomers having a silicon-containing group such as γ- (meth) alkoxypropyltrimethoxysilane, fluorine such as 2- (perfluoro-7-methyloctyl) ethyl acrylate, heptadecafluorodecyl (meth) acrylate Monomers that impart releasability, such as monomers having a system-containing group, Acryloylmorpholine, a monomer having a bulky structure such as lunyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and EO-modified dicyclopentenyl (meth) acrylate And monomers having a cyclic hydrophilic group such as vinylpyrrolidone and vinylcaprolactone.
[0035]
The above example is based on the general formula (1). ₁ And R ₂ Is a methyl group, and X and Y are ethylene groups. However, the present invention is not limited to these, and six R ₁ May each independently be a hydrogen atom or a methyl group; ₂ Specific examples include, for example, methyl group, ethyl group, n- or iso-propyl group, n-, iso- or tert-butyl group, substituted or unsubstituted phenyl group, substituted or unsubstituted benzyl group and the like. Specific examples of X and Y include an ethylene group, a propylene group, a diethylene group, and a dipropylene group. As the total molecular weight of the urethane-modified acrylic resin used in the present invention thus obtained, the average molecular weight in terms of standard polystyrene measured by GPC is 10,000 to 200,000, and more preferably 20,000 to 40,000. preferable.
[0036]
Further, in order to adjust the flexibility and viscosity of the cured ionizing radiation-curable resin layer (relief forming layer 15), the ionizing radiation-curable resin of the present invention includes a normal thermoplastic resin, an acrylic resin, and other resins. Monofunctional or polyfunctional monomers, oligomers and the like can be included. For example, a monofunctional monofunctional (meth) acrylate such as tetrahydrofurfuryl (meth) acrylate, and a bifunctional or higher functionalized polyol (meth) acrylate such as an epoxy-modified polyol (meth) acrylate and a lactone-modified polyol (meth) acrylate when classified according to a skeleton structure. A) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, and other polybutadiene-based, isocyanuric acid-based, hydantoin-based, melamine-based, phosphoric acid-based, imide-based, and phosphazene-based skeletons Various monomers, oligomers, and polymers that are poly (meth) acrylates and are curable by ultraviolet rays and electron beams can be used.
[0037]
The number of functional groups is not particularly limited, but if the number of functional groups is less than 3, the heat resistance tends to decrease, a part of the relief forming layer 15 is damaged, or the relief surface becomes cloudy. If it is 20 or more, the flexibility tends to decrease.
[0038]
The above monomers or oligomers may be used in combination of two or more. The amount used is in the range of 5 to 90 parts by mass, preferably 10 to 70 parts by mass, per 100 parts by mass of the urethane-modified acrylic resin. When the amount of the monomer or oligomer used is less than the above range, the strength, heat resistance, scratch resistance, water resistance, chemical resistance, and adhesion to the substrate 11 of the obtained ionizing radiation-curable resin layer cannot be said to be sufficient. If the amount of the monomer or oligomer exceeds the above range, the tackiness of the surface becomes high, causing blocking, or a part of the material remains on the plate (press stamper) at the time of the relief duplication of the relief hologram, diffraction grating, etc. This phenomenon is not preferred in terms of, for example, the phenomenon that a trader calls plate-cutting), and the repetitive relief duplicating property (embossing property) decreases.
[0039]
Further, when forming (replicating) a relief on the ionizing radiation-curable resin layer (relief forming layer 15), a stamper (metal plate or resin plate) having an uneven relief on the surface of the relief forming layer 15 To form (replicate) the relief on the relief forming layer 15. At this time, a release agent may be previously contained in the relief forming layer 15 so that the stamper can be easily peeled off from the relief forming layer 15. As the release agent, known release agents can be used. Examples of the release agent include solid waxes such as polyethylene wax, amide wax, and Teflon (registered trademark) powder, fluorine-based and phosphate-based surfactants, and silicone. Yes, and particularly preferably, the release agent is a modified silicone. Specifically, modified silicone oil side chain type, modified silicone oil both terminal type, modified silicone oil one terminal type, modified silicone oil side chain both terminal type, methylpolysiloxane containing trimethylsiloxysilicic acid (referred to as silicone resin) ), Silicone-grafted acrylic resin, and methylphenyl silicone oil.
[0040]
Among the above silicone oils, the reactive silicone oil reacts with the resin at the time of curing with ionizing radiation and combines to be integrated. Therefore, it does not bleed out (bleed out) on the surface of the relief forming layer 15 on which the relief unevenness is formed later. This characteristic performance can significantly improve the adhesion between the relief forming layer 15 and the reflective layer 17 provided on the relief surface. The release agent is used in an amount of about 0.1 to 50 parts by weight, preferably about 0.5 to 10 parts by weight, per 100 parts by weight of the ionizing radiation-curable resin. If the amount of the release agent used is less than the above range, peeling between the press stamper and the ionizing radiation-curable resin layer is insufficient, and it is difficult to prevent contamination of the press stamper. On the other hand, when the amount of the release agent used exceeds the above range, repelling occurs at the time of application of the composition, the surface of the coating film surface is roughened, the adhesion to the substrate or the reflective layer is deteriorated, or the transfer is performed. It is not preferable because the coating of the relief forming layer 15 sometimes breaks (the film strength becomes too weak).
[0041]
Furthermore, in order to improve the heat resistance, the film strength, and the adhesion to the reflective layer 17 of the ionizing radiation-curable resin layer (relief forming layer 15) after curing, the ionizing radiation-curable resin of the present invention is preliminarily prepared. An organic metal coupling agent may be contained. Examples of the organic metal coupling agent include known silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents.
It is preferable to use such an organic metal coupling agent in a range of 0.1 to 10 parts by mass per 100 parts by mass of the ionizing radiation-curable resin.
[0042]
The ionizing radiation-curable resin becomes an ionizing radiation-curable resin (relief-forming layer 15) when irradiated with ionizing radiation and cured (reacted) after forming the relief. As the ionizing radiation, ultraviolet (UV), visible light, gamma ray, X-ray, or electron beam (EB) can be used, but ultraviolet (UV) is preferable. The ionizing radiation-curable resin which is cured by ionizing radiation may be added with a photopolymerization initiator and / or a photopolymerization accelerator in the case of ultraviolet curing, and may not be added in the case of electron beam curing with high energy. If a suitable catalyst is present, it can be cured by thermal energy.
[0043]
(Initiator of Relief-Forming Layer) As the photopolymerization initiator, for example, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethylmeuram monosulfide, thioxanthone, etc. can be applied. If necessary, a photosensitizer and a photopolymerization accelerator are added. The content of the photopolymerization initiator and the photosensitizer is preferably in the range of about 0.5 to 10 parts by mass per 100 parts by mass of the urethane-modified acrylic resin.
[0044]
In the ionizing radiation-curable resin composition of the present invention, in addition to the above components, storage stability when a polymerization inhibitor such as phenols such as hydroquinone, quinones such as benzoquinone, phenothiazine, and copper is compounded. improves. Further, if necessary, various assistants such as an accelerator, a viscosity modifier, a surfactant, and an antifoaming agent may be blended. It is also possible to blend a polymer such as styrene / butadiene rubber.
[0045]
As described above, when the release layer 13 is provided, the relief forming layer 15 is made of an ionizing radiation curable resin, and the release layer 13 contains a thermoplastic resin in the ionizing radiation curable resin. When the release layer 13 is not provided, the ionizing radiation curable resin of the relief forming layer 15 does not contain a thermoplastic resin. As the thermoplastic resin, a polyester resin or a vinyl chloride-vinyl acetate copolymer can be used, and at least one kind is used. The thickness of the release layer 13 is usually about 0.1 to 10 μm, preferably 0.2 to 5 μm.
[0046]
When the release layer 13 is provided, the relief forming layer 15 is made of an ionizing radiation-curable resin, and the release layer 13 contains a thermoplastic resin in the ionizing radiation-curable resin in order to increase the adhesion to the base material. The ionizing radiation curable resin is 90 to 99.9% by mass and the thermoplastic resin is 0.1 to 10% by mass in terms of the content in the release layer composition. If the adhesion to the base material 11 is insufficient, the relief forming layer 15 may fall off or burrs may be generated between dots during handling in a transfer foil state. On the other hand, if the amount of the thermoplastic resin used exceeds the above range, the adhesive force with the base material 11 is too strong, so that the transfer is not performed at the time of transfer with the thermal head or the dots are missing, which is not preferable. The thickness of the relief forming layer 15 is usually about 0.1 to 30 μm, preferably 0.2 to 5 μm.
[0047]
The transfer foil without the release layer 13 does not contain a thermoplastic resin in the ionizing radiation-curable resin of the relief forming layer 15. In this case, the thickness of the relief forming layer 15 is usually about 0.2 to 30 μm, preferably 0.5 to 10 μm.
[0048]
(Reflection Layer of Transfer Foil) The reflection layer 17 is provided on the relief layer 17 on the relief forming layer 15 provided with a relief structure such as a hologram or a diffraction grating, so that the reproduced image of the hologram and / or the diffraction grating can be formed. It will be clearly visible. When a metal that reflects light is used as the reflective layer 17, it becomes an opaque type, and when a transparent metal compound having a difference in refractive index from the surface of the relief forming layer 15 is used, it becomes a transparent type. The reflective layer 17 is made of a metal such as Cr, Ti, Fe, Co, Ni, Cu, Ag, Au, Ge, Al, Mg, Sb, Pb, Pd, Cd, Bi, Sn, Se, In, Ga, and Rb. , And oxides, sulfides, nitrides, and other thin films thereof may be used alone or in combination. Preferred metals are aluminum, chromium, nickel, gold and silver.
[0049]
The transparent type reflective layer 17 is made of a transparent metal compound having a refractive index different from that of the relief forming layer 15. Since the optical refractive index is different from that of the relief forming layer, a relief such as a hologram can be visually recognized in almost colorless and transparent hue and without metallic luster. The refractive index of the reflective layer 17 is more effective as the difference in refractive index from the surface of the relief forming layer 15 increases, and the difference in refractive index is 0.3 or more, preferably 0.5 or more, and more preferably 1. 0 or more. For example, ZnS, TiO ₂ , Al ₂ O ₃ , Sb ₂ O ₃ , SiO, TiO, SiO ₂ , ITO, etc. can be applied, preferably ITO or tin oxide, each having a refractive index of 2.0, and having a sufficient difference in refractive index. If the refractive index is small, LiF, MgF ₂ , AlF ₂ and so on. The term “transparent” means that visible light can be sufficiently transmitted, and includes colorless or colored and transparent.
[0050]
The above-mentioned thin film formation of the metal and the transparent metal compound can be obtained by a vacuum thin film method such as a vacuum evaporation method, a sputtering method, or an ion plating method so that the thickness is about 10 to 5000 nm, preferably 20 to 2000 nm. . If the thickness of the reflective layer 17 is less than this range, light is transmitted to some extent and the effect is reduced, and if it is more than that, the reflective effect does not change, so that cost is wasted. In terms of the lame effect, a metal thin film is preferable.
[0051]
(Adhesive Layer of Transfer Foil) A heat-adhesive adhesive which is melted or softened by heat and adheres can be applied to the adhesive layer 19, for example, an ionomer resin, an acid-modified polyolefin resin, an ethylene- (meth) acrylic acid copolymer , Ethylene- (meth) acrylate copolymer, polyester resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, vinyl acetate vinyl resin, (meth) acrylic resin such as acrylic and methacrylic resin, Acrylic ester resin, maleic acid resin, butyral resin, alkyd resin, polyethylene oxide resin, phenolic resin, urea resin, melamine resin, melamine-alkyd resin, cellulose resin, polyurethane resin, polyvinyl ether resin, silicone Resin, rubber-based resin, etc. can be applied. In addition to use.
[0052]
The resin of the adhesive layer 19 is selected in consideration of the affinity with the vinyl chloride resin, the vinyl acetate resin, the vinyl acetate copolymer resin, and the material to be transferred. Generally, an acrylic resin, a butyral resin, and a polyester resin are preferable in terms of adhesive strength and the like. The thickness of the adhesive layer 17 is usually about 0.05 to 10 μm, preferably 0.1 to 5 μm. If the thickness of the adhesive layer 19 is less than this range, the adhesive force with the transfer receiving body is insufficient and the adhesive layer 19 falls off. In addition, the heat of the thermal head is wasted. Furthermore, additives such as a filler, a plasticizer, a coloring agent, and an antistatic agent may be appropriately added to the adhesive layer 19 as necessary. An extender such as silica or calcium carbonate can be used as the filler. In particular, the addition of the extender pigment improves foil breakage. As the antistatic agent, a nonionic surfactant, an anionic surfactant, a cationic surfactant, a polyamide, an acrylic acid derivative, or the like can be used.
[0053]
(Heat-Resistant Protective Layer of Transfer Foil) Further, a heat-resistant protective layer 21 may be provided on the surface of the substrate opposite to the release layer or the relief forming layer. The heat-resistant protective layer 21 has, as basic components, a heat-resistant thermoplastic resin binder and a substance that functions as a heat release agent or a lubricant. The heat-resistant thermoplastic resin binder can be selected from a wide range, but preferred examples include an acrylic resin, a polyester resin, a styrene-maleic acid copolymer, a polyimide resin, a polyamide resin, and a polyamide-imide resin. , Cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate, vinylidene fluoride resin, nylon, polyvinyl carbazole, chlorinated rubber, cyclized rubber and polyvinyl alcohol. These resins are those having a glass transition point of 60 ° C. or higher, or a compound having two or more amino groups or a diisocyanate or triisocyanate added to a thermoplastic resin having an OH group or a COOH group to cause slight crosslinking and curing. It has been empirically known that these are preferred.
[0054]
Heat releasing agents or lubricants to be mixed with the above thermoplastic resin include waxes such as polyethylene wax and paraffin wax, amides, esters or salts of higher fatty acids, and phosphate esters such as higher alcohol and lecithin. There are a type that melts by an excessive heating to exert its function, and a type that is useful as a solid such as a powder of a fluororesin or an inorganic substance. In addition, in addition to these lubricants or thermal release agents, other release agents, for example, a powder of a fluorine-containing resin, a powder of a guanamine resin and wood powder can also be used in combination, in this case, High effects can be obtained.
[0055]
The composition for forming the heat-resistant protective layer 21 is formed by blending the above-mentioned substance acting as a lubricant or a thermal release agent in an amount of 10 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin binder. Application to the base material is performed by kneading with an appropriate solvent to form an ink, and applying the coating material such as a roll coating method, a gravure coating method, a screen coating method, and a fountain coating method in the same manner as a general coating agent application method. Solids content of 0.1 to 4 g / m ² It may be performed by applying and drying according to the degree.
[0056]
A primer layer may be provided on the base 11 in advance in order to ensure the adhesion between the base sheet and the heat-resistant protective layer 21. The primer layer may be mixed with an antistatic agent and subjected to an antistatic treatment. Further, the primer layer is applied in the form of an ink using an appropriate solvent, and the resin of the primer layer can be made water-dispersible or water-soluble. If the solvent is water, it is discharged as a gas by drying, but does not pollute the atmospheric environment. In general, the water-dispersed resin is hard to be redissolved once formed into a film, and is hard to be exposed to the solvent when the heat-resistant protective layer 21 is formed in contact with this layer, so that stable performance is exhibited. be able to.
[0057]
As described above, by using the transfer foil having the heat-resistant protective layer 21, the object to be transferred is expanded, or the transfer (printing, printing) speed is increased, and the surface of the heat-resistant protective layer 21 of the transfer foil is increased. When performing thermal printing with a thermal head, even if this operation is performed under the high energy required to obtain sufficient transfer efficiency, so-called sticking occurs in which the substrate and the thermal head are thermally fused. I can't.
[0058]
(Method of Manufacturing Transfer Foil) Next, a method of manufacturing the transfer foil ribbon used in the present invention will be described. In the method for producing a transfer foil in which a base material / peeling layer / relief forming layer / reflective layer is sequentially laminated, (a) a step of providing a peeling layer on a substrate, and (b) providing a relief forming layer on the surface of the peeling layer (C) forming a relief on the relief-forming layer, (d) irradiating the relief and the release layer with ionizing radiation, and (e) providing a reflective layer on the relief surface. It is a manufacturing method. The transfer foil 1 of the present invention is provided with a release layer 13, a relief forming layer 15, a reflective layer 17, and an adhesive layer 19 on one surface of a substrate 11. The adhesive layer 19 may be provided on the transfer object and is not essential, but is usually provided on the transfer foil. Therefore, the description here includes the formation of the adhesive layer 19.
[0059]
(A) providing a release layer 13 on the substrate 11;
When the release layer 13 and the relief forming layer 15 are provided on one surface of the substrate 11, first, the release layer 13 is provided on one surface of the substrate 11. Various additions of the above-mentioned mono- or polyfunctional monomers and oligomers, release agents, organometallic coupling agents, photo-initiators and the like to the urethane-modified acrylic resin ionizing radiation-curable resin, if necessary. In order to further ensure proper adhesion to the base material, the thermoplastic resin is added in an amount of 0.1 to 10% by mass in the release layer composition and dissolved or dispersed in an organic solvent. Thus, an ionizing radiation-curable resin composition (ink) is obtained.
[0060]
The ionizing radiation-curable resin is a precursor before being cured without irradiation with ionizing radiation, and the ionizing radiation-curable resin is a resin after being cured by irradiation with ionizing radiation. The ionizing radiation-curable resin composition (ink) is applied by a known coating method or printing method and dried. As the coating method, for example, a roll coat, a reverse roll coat, a transfer roll coat, a gravure coat, a gravure reverse coat, and the like can be applied. Examples of the printing method include intaglio printing, stencil printing, flexographic printing, resin letterpress printing, gravure printing, and gravure offset printing.
[0061]
Next, (b) a step of providing a relief forming layer 15 on the release layer surface 13. As the relief forming layer 15, the above-mentioned ionizing radiation-curable resin of the urethane-modified acrylic resin, if necessary, also as described above, the mono- or polyfunctional monomer or oligomer, a release agent, an organometallic coupling agent, Various additives such as a photoinitiator are added, and dissolved or dispersed in an organic solvent to obtain a relief forming layer 15 composition (ink). The composition (ink) of the relief forming layer 15 is applied by a known coating method or printing method and dried. As the coating method or the printing method, the same method as that for forming the release layer can be applied. In addition, there is no tack on the surface of the relief forming layer 15 before curing, and the film can be directly wound into a roll, which is extremely convenient in processing.
[0062]
(C) forming a relief on the relief forming layer 15;
As described above, the relief is formed on the surface of the relief forming layer 15 applied on the base material. The relief has a surface uneven pattern (light diffraction pattern) capable of reproducing a two-dimensional or three-dimensional image. A hologram or diffraction grating in which the intensity distribution of the light of the interference fringes due to the interference between the object light and the reference light is recorded in an uneven pattern can be used as the surface uneven pattern. Examples of holograms include Fresnel holograms, Fraunhofer holograms, lensless Fourier transform holograms, laser holograms such as image holograms, white light holograms such as rainbow holograms, and color holograms, computer holograms, and holograms utilizing these principles. Displays, multiplex holograms, holographic stereograms, holographic diffraction gratings, etc.
[0063]
(Formation of relief) Examples of the diffraction grating include a holographic diffraction grating using hologram recording means. In addition, the diffraction grating can be arbitrarily calculated based on a mechanically created diffraction grating using an electron beam drawing apparatus or the like. And a diffraction grating that can obtain the above-described diffracted light may be used, and may be recorded singly or multiplely, or may be recorded in combination.
[0064]
(Relief Stamper) Usually, the stamping is performed by pressing (so-called embossing) a stamper (metal plate or resin plate) on which the relief is formed on the surface of the relief forming layer 15 and then forming the relief on the surface of the relief forming layer. After forming (replicating) into No. 15, the stamper is peeled off. The stamper that duplicates the relief can use the master itself, but because of the risk of wear and damage, apply a metal plating or ultraviolet curable resin to the master and irradiate it with ultraviolet light to cure it, as with analog records. By a method such as peeling and peeling (referred to by those skilled in the art as the 2P method), replication is performed using a metal or resin, and commercial replication is performed using a replicated mold (stamper).
[0065]
(Relief duplication) A commercial duplication method involves embossing the surface of the relief forming layer 15 using a mold or a resin-type stamper, duplicating the relief, and then irradiating with ionizing radiation. The relief is duplicated by exposing the stamper after irradiation with ionizing radiation. This commercial duplication can be performed in a continuous manner, so that a continuous duplication operation can be performed. In the present invention, as described above, by adding an additive such as a release agent to the relief forming layer 15, for example, even when embossing a diffraction grating or the like, the stamper is not contaminated, and The releasability from the layer 15 is improved, and the stamper can be used continuously for a long period of time (repeated embossability).
[0066]
(D) irradiating the relief and the release layer with ionizing radiation;
The surface of the relief forming layer 15 is irradiated with ionizing radiation during or after embossing with a stamper, or during and after embossing, to cure the ionizing radiation-curable resin. As the ionizing radiation, ultraviolet (UV), visible light, gamma ray, X-ray, electron beam (EB) and the like can be applied, and ultraviolet (UV) is preferable.
[0067]
(UV irradiation) As an ultraviolet (UV) lamp for irradiating ultraviolet rays, a high-pressure mercury lamp or a metal halide lamp can be applied, and the wavelength may be appropriately selected according to the ultraviolet-curable resin composition. The amount of irradiation may be in accordance with the material and amount of the composition, the output of the UV lamp, and the processing speed. Preferably, the wavelength of the ultraviolet ray does not include a region of 300 nm or less, and irradiation of a wavelength of 300 nm or less, particularly 254 nm, makes it impossible to obtain an appropriate separation between the substrate and the release layer due to an excessive crosslinking reaction. Therefore, even when a high-pressure mercury lamp is used, the substrate 11 and the release layer 13 are irradiated with a wavelength-selective filter capable of cutting the light intensity at a wavelength of 300 nm or less from the light intensity of 300 to 400 nm by 99% or more. Adhesive strength can be moderate.
In handling in the state of the transfer foil, the relief forming layer 15 does not fall off, and in the transfer by the thermal head of the thermal printer, high-speed, low-energy, fine-area dots and adjacent dots are not chipped, and burrs are formed. Accurate dots can be transferred without any occurrence.
[0068]
(E) Step of providing reflection layer 17 on relief surface
The reflection layer 17 is formed by a known vacuum thin film method such as a vacuum evaporation method, a sputtering method, and an ion plating method. An adhesive layer 19 is provided on the surface of the reflective layer 17. The adhesive layer 19 is formed by applying a composition (ink) obtained by dispersing or dissolving the above-mentioned heat-adhesive resin in a solvent by a known coating method or printing method and drying. As the coating method or the printing method, the same method as that for forming the release layer can be applied. For drying, a filler may be added or brushing may be performed as necessary to improve transfer suitability.
[0069]
Alternatively, a transfer foil having a configuration in which a relief forming layer is directly provided on the base material 11 without providing the release layer 13 may be used. The method for manufacturing the transfer foil ribbon includes: (a) providing a relief forming layer on the base material; Otherwise, it is the same as the method of manufacturing the transfer foil ribbon having the release layer 13. Here, the step (a) will be described, and other steps will be omitted.
[0070]
(A) providing a relief forming layer 15 on the substrate 11;
The relief forming layer 15 is the same as the formation of the relief forming layer 15 described in the method for manufacturing a transfer foil ribbon having the release layer 13 except that the release layer is not provided. A composition (ink) obtained by dispersing or dissolving the composition in a solvent is applied by a known coating method or printing method, and dried. As the coating method or the printing method, the same method as that for forming the release layer can be applied.
[0071]
(Transfer of Dots) An image display medium transferred (printed) using the transfer foil ribbon and the thermal printer described above will be described.
FIG. 7 shows an image display medium according to an embodiment of the present invention in which dots having different areas are mixed and the dot density is gradient.
FIG. 8 shows an image display medium having an emphasis relationship with an image showing one embodiment of the present invention.
FIG. 9 shows an image display medium having a shape composed of a combination of dots according to an embodiment of the present invention.
FIG. 10 shows an image display medium having a shape composed of dots or a combination of dots, showing one embodiment of the present invention.
The image display medium 105 of the present invention uses a transfer foil ribbon on which a relief hologram or a relief of a diffraction grating is formed, on a medium having at least a colored layer, on the colored layer, and forms a plurality of dots with a thermal head. Transferred, the dot area is 0.0001 to 0.09 mm ² It is sufficient that the diffraction direction of a certain dot is different from that of at least one neighboring dot.
The area of the dot 101 is 0.0001 to 0.09 mm ² Can be applied. Below this range, no diffraction effect is exhibited, and above this range, the synergistic effect of a plurality of dots is weakened and the lame effect is reduced. The dots in this range correspond to the size of the heating element of the thermal head, and may be used depending on the medium to be transferred. That is, 0.0016 mm ² Is equivalent to the area of one dot of the thermal head of 600 dpi required for relatively high resolution such as a card printer. ² Corresponds to the area of one dot of the thermal head of 100 dpi such as a poster printer having a large medium. Further, at the time of thermal printing, a dot area smaller than one dot area of the printer can be transferred by setting the printing energy to the dots as gradation and applying a load in the range of 1 to 100%. For example, one dot of a 600 dpi thermal printer is 0.0016 mm. ² However, by reducing the printing energy applied to the dots, 0.0001 mm smaller than 1 dot ² Can be transferred.
Conventionally, such fine dots cannot be transferred stably without chipping by a thermal head.
[0072]
In FIG. 1, for example, dots having the same area are regularly transferred onto a colored layer of a cloth pattern. The relief of the dot is a diffraction grating, and each dot has a different light diffracting direction from a neighboring dot. The vertical, horizontal, upward-sloping oblique, and downward-sloping oblique lines of the dots shown in FIG. 1 represent relief ridges, and light is diffracted in a direction perpendicular to the ridges. Further, the wave pattern of the dots shown in FIG. 7 represents the ridge of the hologram, and reproduces a three-dimensional image by diffracting light. The area of the dot or the area of the combination of the dots is 0.01 to 1.0 mm ² The transfer occupancy is 5 to 40%, more preferably 10 to 30%, and a particularly remarkable lame effect is exhibited in synergy with a colored layer such as an image or a pattern on a medium. Surprisingly, the design effect was even more pronounced than the real glitter with gold and silver threads. The area of the individual dots or the occupancy of the dots is preferably in this range.If the area is less than this range, the visibility is reduced and the effect is reduced. Would.
[0073]
In FIG. 7, dots having different areas are mixed, and the dot density has a gradient. Furthermore, the inside of one dot is composed of a plurality of portions having different directions of diffracting light. In this way, a unique design effect is achieved by using dots having different areas and different diffraction directions, or by giving a gradient to the dot density. A transfer foil ribbon having reliefs having different diffraction directions may be provided with reliefs having different diffraction directions on a stamper for forming the reliefs. Reliefs having different diffraction directions can be easily obtained by a known multiple imaging method using a laser beam, or by forming a large number of portions having different diffraction directions by electron beam lithography.
[0074]
In FIG. 8, dots are transferred and formed in cooperation with all kinds of patterns such as images, characters, symbols, illustrations, and photographs of the coloring layer 3. Since a plurality of dots are arranged and transferred so as to form a heart shape as a whole, they match the pattern with the colored layer 3 to bring out a high design.
[0075]
The dot itself may be, for example, an arbitrary shape such as a rectangle or a circle, or may be a dot composed of a plurality of dots, for example, a heart, a diamond, a star, a crescent, a circle, a rectangle, or any other area having a different area. Shape and the size can be freely formed. FIG. 9 illustrates various combinations of dot shapes, such as a star, a crescent, a heart, and a triangle having different areas. FIG. 10 shows an example in which dots or dots are combined, and various shapes and sizes can be arbitrarily set as shown in FIGS.
[0076]
【Example】
First, a transfer foil ribbon is manufactured. In the examples, parts and% are based on mass unless otherwise specified. Production examples of the urethane-modified acrylic resin (ionizing radiation-curable resin) used in the present invention are shown below.
A 2-liter four-necked flask equipped with a condenser, a dropping funnel and a thermometer was charged with 40 g of toluene and 40 g of methyl ethyl ketone (MEK) together with an azo-based initiator, 24.6 g of 2-hydroxyethyl methacrylate (HEMA), and methyl methacrylate. (MMA) A mixture of 73.7 g, dicyclopentenyloxyethyl methacrylate, 24.6 g, toluene 20 g, and MEK 20 g was allowed to react at a temperature of 100 to 110 ° C. for 8 hours while being dropped over about 2 hours via a dropping funnel. Then, it was cooled to room temperature.
To this, a mixed solution of 27.8 g of 2-isocyanateethyl methacrylate (manufactured by Showa Denko, Karenz MOI), 20 g of toluene and 20 g of MEK was added, and an addition reaction was carried out using dibutyltin laurate as a catalyst. The reaction product was subjected to IR analysis to confirm the disappearance of the absorption peak at 2200 cm −1 of the isocyanate group, and the reaction was terminated. The resulting urethane-modified acrylate resin solution had a nonvolatile content of 41.0%, a molecular weight of 30,000 as measured by GPC (solvent: THF) in terms of standard polystyrene, and an average of double bonds in one polymer molecule. The number was 13.0 mol%. The obtained ionizing radiation-curable resin is a resin in which, in the general formula (1), dicyclopentenyloxyethyl methacrylate is introduced into Z, -CH3 is introduced into R1 and R2, -C2H4- is introduced into X and Y, and n is 0. It is.
[0077]
Next, a production example of the composition (ink) for a relief forming layer will be described below.
The composition having the following blending ratio was diluted with methyl ethyl ketone (MEK) to adjust the solid content of the composition to 50%, to obtain a composition (ink) for a relief forming layer.
Ionizing radiation curable resin 100 parts
Silicone (Methylpolysiloxane containing trimethylsiloxysilicate, KF-73
12, Shin-Etsu Chemical Co., Ltd., product name) 1 copy
Polyfunctional urethane acrylate (purple UV-1700B, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.
Product name) 25 copies
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals, Inc.
Name) 5 copies
[0078]
Next, a production example of the composition (ink) for a release layer will be described below.
The composition having the following composition ratio was diluted with methyl ethyl ketone (MEK) to adjust the solid content of the composition to 50%, and the composition was used as a release layer composition (ink).
Ionizing radiation curable resin 100 parts
Silicone (Methylpolysiloxane containing trimethylsiloxysilicate, KF-7
312, Shin-Etsu Chemical Co., Ltd., product name) 1 copy
Polyfunctional urethane acrylate (purple light UV-1700B, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
, Product name) 25 copies
Photopolymerization initiator, Irgacure 907
(Ciba Specialty Chemicals, product name) 5 copies
Thermoplastic resin (polyester resin, Byron 29SS)
(Toyobo Co., Ltd., product name) 2 copies
[0079]
(Example of production of transfer foil ribbon)
The composition for the release layer (ink) was dried at a film speed of 100 m / min on a 6 μm-thick polyester terephthalate film (F-53, manufactured by Toray Industries, Inc.) at an easily adhesively treated surface to a thickness of 0.1 m Coating was performed with a roll coater to a thickness of 5 μm, and the coating was dried at 80 ° C. to form a release layer 13. The composition (ink) for a relief forming layer is applied to the surface of the release layer 13 at a film speed of 50 m / min using a gravure reverse coater and dried at 100 ° C. so that the thickness after drying becomes 0.5 μm. Then, the relief forming layer 15 is formed, and the obtained film is not sticky at room temperature and can be stored and post-processed in a wound state.
A relief is formed by pressing (embossing) a stamper onto the surface of the relief forming layer 15. Separately, using an electron beam, a diffraction grating consisting of a square having a diffraction direction different from each other and having a side of 50 μm was formed using a master diffraction grating drawn so as to be laid out without matching the diffraction direction of an adjacent square. From the master relief, the stamper duplicated by the 2P method is adhered to the emboss roller of the duplication apparatus, and heated and pressed (embossed) between the opposing rollers at 150 ° C. to obtain a relief of the diffraction grating having a fine uneven pattern. It was shaped. Immediately after the shaping, the composition was cured by irradiating an ultraviolet ray whose wavelength was 300 nm or less with a high-pressure mercury lamp using a Pyrex (registered trademark) glass as an output window for the ultraviolet ray. Aluminum was evaporated to a thickness of 30 nm on the relief surface by a vacuum evaporation method to form a reflective diffraction grating. An adhesive of a vinyl chloride-vinyl acetate copolymer was applied to the relief surface by gravure coating and dried at 100 ° C. to form an adhesive layer having a thickness of 0.2 μm to obtain a transfer foil. The transfer foil was slit into a predetermined width and loaded into a cassette to obtain a transfer foil ribbon.
[0080]
(Example 1)
The transfer foil ribbon obtained above is loaded on a general thermal printer (300 dpi), and transferred onto a colored layer formed by a sublimation transfer type thermal printer. ² The image display medium shown in FIG.
[0081]
(Examples 2 to 4, Comparative Examples 1 and 2)
Image display media of Examples 2 to 4 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1 except that the dot area and the dot pattern were as shown in Table 1.
[0082]
[Table 1]

[0083]
(Examples 5 to 7)
Image display media of Examples 5 to 7 were obtained in the same manner as in Example 1 except that the dot area and the dot pattern were as shown in Table 2.
[0084]
[Table 2]

[0085]
The obtained image display medium was evaluated based on the degree of lame effect, colored layer discrimination, and hologram design. Regarding the lame effect, the image display medium was visually observed, and those having the lame effect were evaluated as “present”, and those not observed were evaluated as “absent”. The color layer discriminating property and the hologram design property were visually observed, and those that were recognized were judged as acceptable, and those that were not recognized were judged as unacceptable and evaluated as “x”.
[0086]
The evaluation results are shown in the lower columns of Tables 1 and 2. In Examples 1 to 3 and 5 to 7, a lame effect was observed in part or all of the transfer portion, and there was no problem with the colored layer discrimination property and the hologram design property. Further, in Example 4, although the lame effect was slightly reduced, it was practically sufficient, and there was no problem in the colored layer discrimination property and the hologram design property. In Comparative Examples 1 and 2, the lame effect was insufficient, and the colored layer discernability was slightly inferior. In Comparative Example 3, the lame effect was insufficient, and the hologram design was also insufficient.
[0087]
【The invention's effect】
As described above, according to the image display medium of the present invention, a unique decorative effect such as a lame effect is exhibited in synergy with the medium or a colored layer such as an image or pattern on the medium, and The outline of a photograph or a photograph can be made into a heart mark, a gradation, or a variety of shapes by combining dots, and high designability can be obtained.
Furthermore, according to the method for manufacturing an image display medium of the present invention, a general-purpose thermal printer does not require a large number of transfer foils, and can transfer fine dots without burrs or chips very easily in a minimum number of transfer operations. can do. In addition, variable dots can be transferred to individual media, and information can be transferred on demand in real time.
[Brief description of the drawings]
FIG. 1 is a schematic plan view and a sectional view of an image display medium showing one embodiment of the present invention.
FIG. 2 is a schematic sectional view of an image display medium showing one embodiment of the present invention.
FIG. 3 is a schematic sectional view of an image display medium showing one embodiment of the present invention.
FIG. 4 is a schematic sectional view of a transfer foil showing one embodiment of the present invention.
FIG. 5 is a schematic sectional view of a transfer foil showing one embodiment of the present invention.
FIG. 6 is a schematic sectional view of a transfer foil showing one embodiment of the present invention.
FIG. 7 shows an image display medium according to an embodiment of the present invention, in which dots having different areas are mixed and the dot density is gradient.
FIG. 8 is an image display medium having an emphasis relationship with an image showing one embodiment of the present invention.
FIG. 9 is an image display medium having a shape composed of a combination of dots according to an embodiment of the present invention.
FIG. 10 is an image display medium having a shape composed of dots or a combination of dots according to an embodiment of the present invention.
[Explanation of symbols]
1 Transfer foil
11 Substrate
13 Release layer
15 Relief forming layer
17 Reflective layer
19 Adhesive layer
21 Heat-resistant protective layer
100 media
101 dots
103, 103A, 103B coloring layer
105 Image display medium

Claims (4)

In an image display medium in which a relief hologram or a diffraction grating is formed by a plurality of dots on a medium having at least a colored layer, the relief hologram has a dot area of 0.0001 to 0.09 mm ^2. Alternatively, the image display medium is characterized in that the diffraction grating has a reflective layer, and the diffraction direction of a certain dot is different from that of at least one other neighboring dot. 2. The image display medium according to claim 1, wherein the plurality of dots include dots having different areas. The image display medium according to claim 1, wherein the plurality of dots have a gradient in dot density. On a medium having at least a colored layer, a substrate, a release layer substantially composed of an ionizing radiation-curable resin and a thermoplastic resin substantially the same as the ionizing radiation-curable resin of the relief-forming layer, a relief hologram or a diffraction grating. Method for manufacturing an image display medium in which a plurality of dots are transferred by a thermal head using a transfer foil ribbon in which a relief forming layer made of an ionizing radiation curable resin having a relief formed thereon, a reflective layer, and an adhesive layer are sequentially laminated 3. The method for manufacturing an image display medium according to claim 1, wherein the area of the dot is 0.0001 to 0.09 mm ² , and the diffraction direction of a certain dot is different from that of at least one other neighboring dot.

Images