JP3638035B2 - Image receiving sheet material and transfer image forming method - Google Patents

Description

【００１９】
ウレタン系オリゴマ−の例としては一般的なイソシアネ−トとポリエ−テルジオ−ルやポリエステルジオ−ルの重合物を使用することが可能であり、芳香族系ウレタンアクリレ−トや脂肪族系ウレタンアクリレ−トのオリゴマ−の使用が好適である。
【００２０】
更に、好ましい可塑剤の他の例としてはエチレン基とカルボン酸のビニルエステル基の共重合体やエチレン基とアクリル酸エステル基を含有する共重合体が挙げられる。カルボン酸の例としては飽和脂肪族モノカルボン酸である酢酸、プロピオン酸、酪酸、ステアリン酸等が挙げられ、その他、不飽和脂肪酸、炭素環カルボン酸、複素環カルボン酸等が挙げられる。アクリル酸エステルの例としてはメチルアクリレート、エチルアクリレート、ブチルアクリレート、２ーエチルヘキシルアクリレート、メトキシ・エチルアクリレート、メチルメタアクリレート、エチルメタアクリレート、ブチルメタアクリレートヘキシルメタアクリレート、デシルオクチルメタアクリレート、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、ジメチルアミノエチルメタアクリレート、メタクリルアマイド等が挙げられる。また、共重合体の成分としては使用目的に合わせて適宜多元系とすることができる。
【００２１】
上記の可塑剤は分子量が１０００以上でかつクッション性の発現性の良いものを使用するときに限り本発明の効果が生じるものである。分子量がこれよりも小さい場合は受像シ−トの表面上に可塑剤が移行しやすくなり受像シ−ト表面上のべとつきを増加させステイッキングやゴミ欠陥等の問題点を引き起こす。また、分子量も大きければ良いわけでなくバインダ−との相溶性が重要であり、分子量が大きくなると各種バインダ−に相溶しずらくなったり、クッション性が劣るために膜厚をアップしなければならないといった問題点が生じる。
【００２２】
添加する可塑剤の分子量は５０００以下であることが好ましいが分子量が５０００以上でも、層のヤング率が１０〜１００００ｋｇ・ｆ／ｃｍ²の範囲に入る場合はこの範囲の分子量で有る必要はない。
【００２３】
また、必要に応じて、受像一層等のクッション性を有する層に補助バインダーとしてアクリルゴムや線状ポリウレタンを添加すると、可塑剤の添加量を低下させることができ、可塑剤の表面へのブリードを抑えられ、ゴミ欠陥や表面粘着性悪化による耐接着悪化を防止することが可能となる。
【００２４】
受像一層の有機高分子物質の厚さは１μｍから５０μｍが好ましく，特に５μｍから３０μｍが好ましい。この理由の１つは受像シート材料上に転写された画像を永久支持体に転写する場合に永久支持体の表面の凹凸より厚くする必要があること，第２の理由は４色のカラー画像が重なる部分のレリーフ段差を充分に吸収しうる厚みが必要な為である。さらに第３の理由は充分なクッション性を得る為である。
【００２５】
次にこの上に設ける受像二層について説明する。受像二層の目的は永久支持体への再転写時に受像シート材料を剥離する際，受像一層と受像二層の間で層間剥離をさせ永久支持体上の画像上に薄い受像二層のみを残し，永久支持体の凹凸により，特別なマット化処理をほどこすことなく実際の印刷物の光沢に近似した画像を得ることにある。さらに第２の目的は画像の耐傷性の向上にある。
受像二層の素材としては種々の物質が基本的に可能であるが，受像二層を構成する有機高分子物質としてポリビニルブチラール樹脂と下記一般式（１）を繰り返し単位とする高分子化合物を含有することが好ましい。
一般式（１）
【００２６】
【化２】

【００２７】
一般式（１）の高分子化合物は一般式（２）で示される単量体を常法に従い適当な溶媒中又は無溶媒で重合開始剤の存在下で重合、もしくは他の単量体と共重合させることにより得られる。
一般式（２）
【００２８】
【化３】

【００２９】
一般式（２）のＡがアミド結合を有する置換基の場合としては例えばＣＯＮＨＲ₂、ＣＯＮＲ₂Ｒ₃が挙げられる。Ｒ₂、Ｒ₃は各々独立に水素、又は炭素原子数１〜１８のアルキル基、炭素数６〜２０のアリール基（該アルキル、アリール基はヒドロキシ基、炭素数１〜６のアルコキシ基、ハロゲン、シアノ基の１つ以上、およびこれらの２種以上の組合せで置換されてても良い）、Ｒ₂とＲ₃が結合しては炭素数１〜２０のアルキレン、アラルキレン（該アルキレン、アラルキレンは分岐を有してもよく、またエーテル結合、−ＯＣＯ−、−ＣＯＯ−、及びこれらの２種以上の組合せを含んでもよい）、又、Ａが含窒素ヘテロ環の場合、イミダゾール類、ピロリドン類、ピリジン類、カルバゾール類などが挙げられ、それらは炭素数１〜５のアルキル基、炭素数６〜１０のアリール基、ハロゲン、シアノ基及びこれら２種以上の組み合わせで置換されていてもよい。
【００３０】
一般式（１）のＡのより好ましい範囲はアミド結合を有する置換基の場合、ＣＯＮＨＲ₂'、ＣＯＮＲ₂'Ｒ₃'；Ｒ₂'，Ｒ₃'は各々独立に水素、又は炭素数１〜１０のアルキル基炭素数６〜１５のアリール基（該アルキル、アリール基はヒドロキシ基炭素数１〜６のアルコキシ基）、Ａが含窒素ヘテロ環の場合は、イミダゾール類、トリアゾール類が挙げられ、それらは炭素数１〜５のアルキル基、炭素数６〜１０のアリール基で置換されていてもよい。
【００３１】
一般式（１）の具体例としては、（メタ）アクリルアミド、Ｎ−アルキル（メタ）アクリルアミド（該アルキル基としては、例えばメチル基、エチル基、プロピル基、ブチル基、ｔ−ブチル基、ヘプチル基、オクチル基、エチルヘキシル基、シクロヘキシル基、ヒドロキシエチル基、ベンジル基などがある）、Ｎ−アリール（メタ）アクリルアミド（該アリール基としては、例えばフェニル基、トリル基、ニトロフェニル基、ナフチル基、ヒドロキシフェニル基などがある）、Ｎ−Ｎ−ジアルキル（メタ）アクリルアミド（該アルキル基としては、例えばメチル基、エチル基、ブチル基、イソブチル基、エチルヘキシル基、シクロヘキシル基などがある）、Ｎ−Ｎ−ジアリール（メタ）アクリルアミド（該アリール基としては、例えばフェニル基がある）、Ｎ−メチル−Ｎ−フェニル（メタ）アクリルアミド、Ｎ−ヒドロキシエチル−Ｎ−メチル（メタ）アクリルアミド、Ｎ−２アセトアミドエチル−Ｎ−アセチル（メタ）アクリルアミド、Ｎ−（フェニルスルホニル）（メタ）アクリルアミド、Ｎ−（ｐ−メチルフェニルスルホニル）（メタ）アクリルアミド、２および３および４−ヒドロキシフェニルアクリルアミド、（メタ）アクリロイルモルホリン、１−ビニルイミダゾール、１−ビニル−２−メチルイミダゾール、１−ビニルトリアゾール、１−ビニル−３，５−ジメチルイミダゾール、ビニルピロリドン、４−ビニルピリジン、ビニルカルバゾール等が挙げられる。
【００３２】
次に一般式（２）で示される単量体と共重合可能な他の単量体の具体例としては、（メタ）アクリル酸エステル類、（メタ）アクリルアミド類、アリル化合物、ビニルエーテル類、ビニルエステル類、スチレン類、クロトン酸エステル類などから選ばれる重合性不飽和結合を有する化合物が挙げられる。具体的には（メタ）アクリル酸エステル類、例えばアルキル（メタ）アクリレート、又は置換（メタ）アルキルアクリレート、（例えばメチル（メタ）アクリレート、エチル（メタ）アクリレート、プロピル（メタ）アクリレート、イソプロピル（メタ）アクリレート、ブチル（メタ）アクリレート、アミル（メタ）アクリレート、ヘキシル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート、エチルヘキシル（メタ）アクリレート、オクチル（メタ）アクリレート、ｔ−オクチル（メタ）アクリレート、クロロエチル（メタ）アクリレート、アリル（メタ）アクリレート、２−ヒドロキシエチル（メタ）アクリレート、２−ヒドロキシプロピル（メタ）アクリレート、４−ヒドロキシブチル（メタ）アクリレート、２，２−ジメチル−３−ヒドロキシプロピル（メタ）アクリレート、５−ヒドロキシペンチル（メタ）アクリレート、トリメチロールプロパンモノ（メタ）アクリレート、ペンタエリスリトールモノ（メタ）アクリレート、ベンジル（メタ）アクリレート、メトキシベンジル（メタ）アクリレート、クロロベンジル（メタ）アクリレート、フルフリル（メタ）アクリレート、テトラヒドロフルフリル（メタ）アクリレート、フェノキシエチル（メタ）アクリレートなど）、アリール（メタ）アクリレート（例えばフェニル（メタ）アクリレート、クレジル（メタ）アクリレート、ナフチル（メタ）アクリレートなど）、スチレン類、例えばスチレン、アルキルスチレン（例えばメチルスチレン、ジメチルスチレン、トリメチルスチレン、エチルスチレン、ジエチルスチレン、イソプロピルスチレン、ブチルスチレン、ヘキシルスチレン、シクロヘキシルスチレン、デシルスチレン、ベンジルスチレン、クロロメチルスチレン、トリフルオロメチルスチレン、エトキシメチルスチレン、アセトキシメチルスチレンなど）、アルコキシスチレン（例えばメトキシスチレン、４−メトキシ−３−メチルスチレン、ジメトキシスチレンなど）、ハロゲノスチレン（例えばクロロスチレン、ジクロロスチレン、トリクロロスチレン、テトラクロロスチレン、ペンタクロロスチレン、ブロモスチレン、ジブロモスチレン、ヨードスチレン、フルオロスチレン、トリフルオロスチレン、２−ブロモ−４−トリフルオロスチレン、４−フルオロ−３−トリフルオロメチルスチレンなど）、ヒドロキシスチレン等；クロトン酸エステル類、例えば、クロトン酸アルキル（例えばクロトン酸ブチル、クロトン酸ヘキシル、グリセリンモノクロトネートなど）、（メタ）アクリル酸、クロトン酸、イタコン酸、アクリロニトリルがある。
【００３３】
この様な一般式（１）で示される繰り返し単位を有する重合体の好ましい具体例としては、Ｎ，Ｎ−ジメチルアクリルアミド／ブチル（メタ）アクリレ−ト共重合体、Ｎ，Ｎ−ジメチル（メタ）アクリルアミド／２−エチルヘキシル（メタ）アクリレ−ト共重合体、Ｎ，Ｎ−ジメチル（メタ）アクリルアミド／ヘキシル（メタ）アクリレ−ト共重合体、Ｎ−ブチル（メタ）アクリルアミド／ブチル（メタ）アクリレ−ト共重合体，Ｎ−ブチル（メタ）アクリルアミド／２−エチルヘキシル（メタ）アクリレ−ト共重合体、Ｎ−ブチル（メタ）アクリルアミド／ヘキシル（メタ）アクリレ−ト共重合体、（メタ）アクリロイルモルホリン／ブチル（メタ）アクリレ−ト共重合体，（メタ）アクリロイルモルホリン／２−エチルヘキシル（メタ）アクリレ−ト共重合体，（メタ）アクリロイルモルホリン／ヘキシル（メタ）アクリレ−ト共重合体，１−ビニルイミダゾ−ル／ブチル（メタ）アクリレ−ト共重合体，１−ビニルイミダゾ−ル／２−エチルヘキシル（メタ）アクリレ−ト共重合体、１−ビニルイミダゾ−ル／ヘキシル（メタ）アクリレ−ト共重合体等が挙げられる。また、一般式（１）の単位の好ましい含有率は１０〜１００モル％であり更に好ましくは３０〜８０モル％である。一般式（１）の単位の含有率が１０モル％未満では画質品質が劣る。好ましい分子量の範囲としては１０００〜２０００００であり更に好ましくは２０００〜１０００００である。分子量が１０００未満では製造が難しく２０万を越えると溶剤への溶解性が低下する。
【００３４】
これらの樹脂と併用が可能な樹脂は種々あるが、例えばポリエチレン、ポリプロピレンなどのポリオレフィン、エチレンと酢酸ビニルあるいはエチレンとアクリル酸エステルあるいはエチレンとアクリル酸の如きエチレン共重合体、ポリ塩化ビニル、塩化ビニルと酢酸ビニルの如き塩化ビニル共重合体、ポリ塩化ビニリデン、塩化ビニリデン共重合体、ポリスチレン、スチレンとマレイン酸エステルの如きスチレン共重合体、酢酸ビニル共重合体、ブチラール樹脂、変成されたポリビニルアルコール、共重合ナイロン、Ｎ−アルコキシメチル化ナイロンの如きポリアミド樹脂、合成ゴム、塩化ゴム、フェノール樹脂、エポキシ樹脂、ウレタン樹脂、尿素樹脂、メラミン樹脂、アルキッド樹脂、マレイン酸樹脂、ヒドロキシスチレン共重合体、スルフォンアミド樹脂、エステルガム、セルロース樹脂、ロジン、等が挙げられる。
【００３５】
これら樹脂に添加される一般式（１）の化合物は好ましくは５〜５０重量％でありこれ以上の添加では受像二層表面がべとつき取扱い上支障をきたす。特に好ましい範囲としては１０〜３０重量％である。
【００３６】
また、これら樹脂の中には各種界面における接着力の関係を満たす為に他の密着改良剤、離型剤、可塑剤、界面活性剤等を添加することができるのは当然である。受像二層に用いる塗布溶剤としては塗布時における塗布溶剤の下層への浸透による受像一層と受像二層の混ざり込みを防ぐ目的で、受像一層に用いた樹脂を溶解もしくは膨潤させないような塗布溶剤を用いることが必要である。例えば、各種の溶剤に対して比較的溶解性の良好な塩化ビニル系の樹脂を受像一層に使った場合にはアルコール系もしくは水系の塗布溶剤を使用することが好ましい。受像二層の膜厚としては，０．１μｍ〜１０μｍが好ましく特に０．５μｍ〜５μｍが好ましい。膜厚が厚すぎると永久支持体の表面の凹凸感が損なわれ，光沢が出過ぎて印刷物近似性を悪くする。
【００３７】
永久支持体への転写時に受像シート材料の剥離で、受像一層の有機高分子物質と受像二層の有機高分子物質の間で層間剥離を起こさせるには各層間の密着力のバランスが重要であるが，層間密着力のコントロールにおいて本発明で利用した重層塗布時の混合を防ぐ為に塗布溶剤の選択の他に，親水性ポリマーと親油性ポリマーあるいは極性ポリマーと非極性ポリマーの組み合わせといった素材の選択，又シランカップリング剤等の密着改良剤，フッ素系やシリコーン系の離型硬化を有する各種添加剤，界面活性剤，可塑剤等を受像一層あるいは受像二層に添加することが有効である。
【００３８】
上記受像一層と受像二層の間には、転写性の調整等の目的で、中間層を設けることもできる。
【００３９】
次ぎに、本発明に有用な、熱転写可能なインキ層を有する転写材料（以下、「熱転写シート」と称する）について説明する。
【００４０】
熱転写シートの支持体としては、従来の溶融転写や昇華転写用支持体として公知の種々の支持体が使用されるが、通常のサーマルヘッド転写感材と同様に厚み５μｍ前後の裏面に離型処理を施したポリエステルフィルムが特に好ましい。
【００４１】
熱転写シートのインキ層に含まれる顔料としては種々の公知の顔料が使用でき、例えばカーボンブラック、アゾ系、フタロシアニン系、キナクリドン系、チオインジゴ系、アンスラキノン系、イソインドリン系などの顔料が挙げられる。これらは２種以上組み合わせて使用することも可能であり、又色相調整のため公知の染料を添加しても良い。
【００４２】
熱転写シートのインキ層に含まれる、軟化点が５０℃〜１５０℃の非晶質有機高分子結合体としては、例えばブチラール樹脂、ポリアミド樹脂、ポリエチレンイミン樹脂、スルホンアミド樹脂、ポリエステルポリオール樹脂、石油樹脂、スチレン、ビニルトルエン、α−メチルスチレン、２−メチルスチレン、クロルスチレン、ビニル安息香酸、ビニルベンゼンスルホン酸ソーダ、アミノスチレン等のスチレン及びその誘導体、置換体の単独重合体や共重合体、メチルメタクリレート、エチルメタクリレート、ブチルメタクリレート、ヒドロキシエチルメタクリレート等のメタクリル酸エステル類及びメタクリル酸、メチルアクリレート、エチルアクリレート、ブチルアクリレート、α−エチルヘキシルアクリレート等のアクリル酸エステル及びアクリル酸、ブタジエン、イソプレン等のジエン類、アクリロニトリル、ビニルエーテル類、マレイン酸及びマレイン酸エステル類、無水マレイン酸、ケイ皮酸、塩化ビニル、酢酸ビニル等のビニル系単量体の単独あるいは他の単量体等との共重合体を用いることができる。
これらの樹脂は２種以上混合して用いることもできる。
【００４３】
これらの内、後に述べる本発明の特徴である分散性の観点からブチラール樹脂やスチレン／マレイン酸ハーフエステル樹脂などが特に好ましい。これら樹脂の軟化点は４０℃〜１５０℃の範囲で選ばれるべきである。１５０℃を越えると熱記録感度が低く、他方４０℃未満ではインキ層の耐接着性が劣る。
【００４４】
これらインキ層には、熱印字の際のインキ層の支持体からの離型性及び熱感度向上の観点から種々の離型剤や軟化剤をインキ層総量に対して１重量％から２０重量％の範囲で加えることも可能である。具体的には、例えばパルミチン酸、ステアリン酸等の高級脂肪酸、ステアリン酸亜鉛の如き脂肪酸金属塩類、脂肪酸エステル類もしくはその部分ケン化物、脂肪酸アミド類等の脂肪酸誘導体、高級アルコール類、多価アルコール類のエステル等誘導体、パラフインワックス、カルナバワックス、モンタンワックス、ミツロウ、木ロウ、キヤンデリラワックス等のワックス類、粘度平均分子量が約１，０００から約１０，０００程度の低分子量ポリエチレン、ポリプロピレン、ポリブチレン等のポリオレフイン類、或いはオレフイン、α−オレフイン類と無水マレイン酸、アクリル酸、メタクリル酸等の有機酸、酢酸ビニル等との低分子量共重合体、低分子量酸化ポリオレフイン、ハロゲン化ポリオレフイン類、ラウリルメタクリレート、ステアリルメタクリレート等長鎖アルキル側鎖を有するメタクリル酸エステル、アクリル酸エステル又はパーフロロ基を有するアクリル酸エステル、メタクリル酸エステル類の単独もしくはスチレン類等のビニル系単量体との共重合体、ポリジメチルシロキサン、ポリジフエニルシロキサン等の低分子量シリコーンレジン及びシリコーン変性有機物質等、更には長鎖脂肪族基を有するアンモニウム塩、ピリジニウム塩等のカチオン性界面活性剤、或いは同様に長鎖脂肪族基を有するアニオン、ノニオン界面活性剤、パーフロロ系界面活性剤等、から１種以上選択して用いることができる。
【００４５】
これら熱転写可能なインキ層の光学濃度は、先に述べた理由により、白色支持体上に熱転写した際にその反射濃度が１．０以上なければならない。
又膜厚は０．２μｍから１．０μｍの範囲が好ましい。１．０μｍよりも大きな厚いインキ層においては面積階調のみによる階調再現性において、シャドウ部がつぶれやすかったり、ハイライト部がとびやすかったりして、結果的に階調再現性が劣ることになる。一方、０．２μｍより下の膜厚では、所定の濃度を出すことが難しい。
【００４６】
これらの薄膜で所定の濃度を出すためには、該インキ層中、顔料が３０重量部から７０重量部、非晶質有機高分子結合体が２５重量〜６０重量部で、必要に応じ添加される離型性物質や軟膜剤の総量が１重量部から１５重量部であることが好ましい。
顔料比率がこれ以下では上記所定の膜厚で所定の濃度を出すことが難しい。
又顔料の粒径は顔料の７０％以上が１．０μｍ以下であることが必要である。粒径が大きい場合にはカラー再現時の各色の重なり部の透明性が損なわれ、かつ先の膜厚と濃度の関係の両者を満たすことが困難になる。
【００４７】
これら顔料の、非晶質有機高分子結合体への分散に関しては、適切な溶剤を加えて、ボールミルを初めとする塗料分野で使用される種々の分散方法が適用される。
【００４８】
上記熱転写可能なインキ層は主成分が顔料と非晶質の有機高分子結合体であり、かつ従来のワックス溶融型に比べ、顔料比率も高く、通常の溶融型に比べ熱転写時の粘度が１０²〜１０³cps のように低くなることはなく、１５０℃の温度において少く共１０⁴cpsよりも高いので、本発明は、受容シートの熱接着性、あるいはカラー像作成の場合はインキ層間の熱接着性を利用した薄膜剥離現像タイプの画像形成であるということができる。このことがインキ層の薄層化の効果と相いまって、高解像力性を維持した上で、シャドウ部からハイライト部に到る広い階調再現を可能にし、かつエッジシャープネスを良好にし、更に１００％の画像の転写を可能にすることにより、例えば４ポイントの小さな文字とベタ部の濃度の均一性を実現した。
【００４９】
以下，本発明を実施例をもって更に詳細に説明するが，本発明はこれらに限定されるものではない。
【００５０】
【実施例】
合成例１
＜高分子化合物（ａ）の合成＞
プロピレングリコ−ルモノメチルエ−テル１７０部を窒素気流下８０℃にて加熱撹拌し、２，２’−アゾビス（２，４−ジメチルバレロニトリル）０．０７部を加え３０分間撹拌した。これにブチルアクリレ−ト３１．６部、Ｎ，Ｎ−ジメチルアクリルアミド２４．４部、２，２’−アゾビス（２，４−ジメチルバレロニトリル）０．０７部を３０分間かけて適下した。滴下終了の３０分後と１時間後に更に２，２’−アゾビス（２，４−ジメチルバレロニトリル）をそれぞれ０．１５部添加し、更に４時間加熱撹拌し、下記高分子化合物（ａ）の２８％プロピレングリコ−ルモノメチルエ−テル液を得た。重量平均分子量は（ポリスチレン換算）１３０００であった。
【００５１】
実施例１
（受像シ−トの作成）
下記の組成を有する受像一層及び受像二層用の塗布液を調整した。

【００５２】

【００５３】
厚さ１００μｍのポリエチレンテレフタレ−ト（ＰＥＴ）フィルムを支持体上に、回転塗布機（ホエラ−）を使用して上記受像一層用塗布液を３００ｒｐｍで塗布し、１００℃のオ−ブン中で２分間乾燥した。得られた受像一層の膜厚は２０μｍであった。
【００５４】
上記受像一層上に、回転塗布機（ホエラ−）を使用して上記受像二層用塗布液を２００ｒｐｍで塗布し、１００℃のオ−ブン中で２分間乾燥した。得られた受像二層の膜厚は２μｍであった。
【００５５】
（熱転写シートの作成）
次いで下記の３種のインキ層用塗布液を調整した。

【００５６】
上記Ａ，Ｂ，Ｃの顔料分散液各々１０重量部に対しステアリン酸アミド０．２４重量部、ｎ−プロピルアルコ−ル６０重量部を加え塗布液とし、厚み５μｍの裏面に離型処理されたポリエステルフィルム（帝人（株）製）に乾燥膜厚Ａが０．３６μｍ、Ｂが０．３８μｍ、Ｃが０．４２μｍになるように塗布し熱転写シートを作成した。
【００５７】
まずシアンの熱転写シ−トと受像シ−トを重ね、副走査分割法によるサ−マルヘッド記録装置（試作実験機）により印字した。この原理は７５μｍＸ５０μｍのヘッドを５０μｍ方向に微小送り３μｍピッチでオンオフする事により面積階調のみの多段階変調を行う方式である。
このシアンの熱転写シ−トを剥離し、受像シ−ト上に面積階調のみよりなる画像を形成させた。次にマゼンタの熱転写シ−トをシアン画像が形成されている受像シ−トに重ね、位置を合わせて同様に印字し、該転写シ−トを剥離する事により受像シ−ト上にマゼンタ画像、同様にしてイエロ−画像を形成させ受像シ−ト上に面積階調のみよりなるカラ−画像を形成させた。次にカラ−画像が形成された受像シ−トをア−ト紙と重ね１３０℃、４．５Ｋｇ／ｃｍの圧で、４ｍ／ｓｅｃの熱ロ−ラ−を通した後、受像シ−トのポリエステルフィルムを剥しインク画像がのった受像二層を転写し、ア−ト紙上にカラ−画像形成させた。このカラ−画像はリス原稿から作成したケミカルプル−フ（富士写真フィルム（株）製、商品名カラ−ア−ト）とカラ−画像の近似性が非常に良好であった。 なおこの際の各単色の反射濃度は下記の通りであった。

また、４Ｐの文字の濃度をミクロデンシトメ−タ−で測定したところ、ベタ部の濃度と同様であった。
【００５８】
階調再現性は５％〜９５％が再現され、非常に良好であった。更に、受像シ−ト表面上のべとつき感が無く、ゴミによる欠陥もなく、ドット形状が良好で、紙の凹凸に追随して表面がマット化され表面光沢が印刷物に非常に近似した画像であった。
【００５９】
実施例２
（受像シ−トの作成）
下記の組成を有する受像一層及び受像二層用の塗布液を調整した。

【００６０】

【００６１】
上記塗布液を用いて、実施例１と同様にして受像シートを作成した。得られた受像シ−トと、実施例１と同様にして作成した熱転写シートを使用して実施例１と同様にしてカラ−画像を形成し、画像の評価を行った。その評価結果を表１に示す。
【００６２】
実施例３
実施例１の受像一層のＤＰＣＡ−１２０の代わりに芳香族系ウレタンオリゴマ−（ＥＢ−６６００、分子量１５９８、ダイセルユ−シ−ビ−（株）製）を用いた以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成し、画像の評価を行った。その評価結果を表１に示す。
【００６３】
実施例４
実施例１の受像一層のＤＰＣＡ−１２０の代わりにウレタンオリゴマ−（Ｕ−２００１ＢＡ−２３、分子量４２６０、新中村化学工業（株）製）を用いた以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成し、画像の評価を行った。その評価結果を表１に示す。
【００６４】
実施例５
実施例１において、受像一層に添加する可塑剤ＤＰＣＡ−１２０を９重量部に変え、補助バインダーとしてアクリルゴム（ＲＳ−０８、日信化学工業（株）製）３重量部を添加した以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成し、画像の評価を行った。その評価結果を表２に示す。
【００６５】
実施例６
実施例１において、受像一層に添加する可塑剤ＤＰＣＡ−１２０を９重量部に変え、補助バインダーとして線状ポリウレタン（デスモコール４０６、住友バイウレタン（株）製）３重量部を追加して添加した以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成し、画像の評価を行った。その評価結果を表２に示す。
【００６６】
実施例７
実施例１において、受像一層に添加する可塑剤ＤＰＣＡ−１２０をポリエステル系可塑剤（パラプレックスＧ−２５、分子量８０００、ロームアンドハースジャパン社製）１２重量部に変えた以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成し、画像の評価を行った。その評価結果を表２に示す。
【００７０】
実施例８
実施例１の受像一層の塩ビー酢ビ共重合体とＤＰＣＡ−１２０の代わりにエチレンーアクリル酸エステルー極性モノマー共重合体（エルバロイＬ７４２、分子量２５００００以上、三井ーデユポンポリケミカル（株）製）を用い、さらにポリエステル系可塑剤Ｗ−２０（大日本インキ化学工業（株）製）を２重量部加えた以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成し、画像の評価を行った。その評価結果を表３に示す。
【００７１】
比較例１
実施例１の受像一層のＤＰＣＡ−１２０の代わりにＴＰＰ（正燐酸エステル系可塑剤、大八化学（株）製、分子量３２６）を用いた以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成したが、非常に表面がべとつき、ゴミ欠陥が多く、更にドット形状が悪く、再現階調性に劣るものであった。
【００７２】
比較例２
実施例１の受像一層のＤＰＣＡ−１２０の代わりにテトラメチロ−ルメタンテトラアクリレ−ト（４官能アクリルモノマ−、商品名Ａ−ＴＭＭＴ、新中村化学（株）製、分子量３５２）を用いた以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成したが、非常に表面がべとつき、ゴミ欠陥が多く、更にドット形状が悪く取扱い性の非常に悪いものであった。
【００７３】
比較例３
実施例１の受像層第一層のＤＰＣＡ−１２０を抜いた以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成したところ、表面のベトツキはなかったが、ゴミ欠陥が多く、更にドット形状が悪く階調性に劣る画像であった。
【００７４】
比較例４
実施例１の受像一層のＤＰＣＡ−１２０の代わりにウレタンオリゴマ−（Ｕ−３４０ＡＸ、分子量１２０００、新中村化学工業（株）製）を用いた以外は実施例１と同様にして受像シ−トを作成した。この受像シ−トを用い実施例１と同様にカラ−画像を形成し、画像の評価を行った。その評価結果を表１に示す。
【００７５】

【００７６】

【００７７】
【表１】

【００７８】
【発明の効果】
本発明の受像シ−ト材料及び転写画像形成方法により、受像シ−ト表面上のべとつきやステイッキングの発生を引き起こすこと無く、記録感度、ドット品質、階調性に優れ、特に印刷物近似性に優れた画像が得られるものである。[0001]
[Industrial application fields]
The present invention is an image-receiving sheet material useful in a heat-sensitive transfer recording system, and a thermal ink layer containing a color material is transferred onto the image-receiving sheet material by using a thermal head or by irradiating a laser beam to form an image, Next, the present invention relates to an image forming method in which an image is formed on a permanent support by retransfer.
[0002]
[Prior art]
In recent years, with the progress of OA, copying machines, printers, and the like using various recording methods such as an electrophotographic method, an ink jet method, a thermal transfer recording method, and the like are used according to each application. A color material is used for this image formation. Usually, a composition containing the color material is melted, or the color material is evaporated and sublimated to cause a recording medium such as paper or film sheet by the action of adhesion, adsorption, dyeing and the like. I'm getting an image on top.
[0003]
Among these, the thermal transfer recording method has advantages such as easy operation and maintenance, miniaturization of the apparatus, and cost reduction. The following two types of thermal transfer recording systems are conventionally known. That is, a heat melting type in which a transfer sheet having a meltable ink layer on a support is heated imagewise (imagewise) with a laser or a thermal head, and the meltable ink is melted and transferred to an image receiving sheet for thermal transfer recording. Sublimation in which the thermal diffusible dye is diffused and transferred to an image receiving sheet for thermal transfer recording using a transfer method and an ink sheet having a thermal diffusible dye (sublimation dye) on a support. There are two types of mold dye transfer systems.
[0004]
The sublimation dye transfer system can control the gradation of the image by changing the transfer amount of the dye according to the change in the thermal energy of the thermal head, so by performing overprinting of cyan, magenta and yellow There is an advantage that a color image having a continuous change in color shading can be obtained. However, this method has the following problems.
(1) It reproduces the gradation of an image mainly using density gradation, and is suitable for some consumer purposes that prefer gradation similar to a photograph. It is not suitable for color proofing used in the printing field where gradation reproduction is performed.
(2) Since the image formation uses dye sublimation, the edge sharpness of the finished image is not sufficient, and the solid density of the thin line is lower than that of the thick line. This is a big problem especially with respect to the quality of the character image.
{Circle around (3)} Durability in fields where image durability is low and heat resistance and light resistance are required is limited.
(4) Since the thermal recording sensitivity is lower than that of the thermal melting type transfer system, it is not suitable as a high-speed recording material using a high resolution thermal head expected in the future.
(5) The photosensitive material is more expensive than the heat melting type transfer material.
[0005]
On the other hand, the hot-melt transfer method has advantages such as higher thermal sensitivity, better light resistance of images, and less expensive materials than the sublimation dye transfer method. There are some disadvantages.
(1) Since gradation reproduction is not density gradation but binary recording, it is inferior in multi-gradation.
(2) Usually, a crystalline wax having a low melting point is used as a binder for the ink layer, so that the resolving power is reduced due to bleeding during thermal printing, and the strength of the transferred image is low.
(3) When crystalline waxes are used, it is difficult to obtain a transparent image due to light scattering of the crystalline phase.
[0006]
In view of such a situation, the present inventors are new to obtain a multi-gradation pigment color image only with the area gradation of binary recording, which is different from the conventional sublimation dye transfer method and heat melting type transfer method. As a heat-sensitive recording material, a thermal adhesive thin film peeling method was previously proposed (Japanese Patent Application No. 5-263695). According to this method, a multi-tone high-quality color image and monochrome image that achieves a drastic improvement in the problems of the conventional thermal transfer recording method with a pigment transfer method with area gradation only, have been achieved. In other words, it is possible to expand into the card field, the outdoor display field, the meter display field, etc. by taking advantage of the light resistance of color proofs, block originals, and pigments in the printing field.
[0007]
On the other hand, various proposals have been made for transfer materials used for these various thermal transfer recording materials. When plain paper is used as the image-receiving medium for the sublimation dye transfer system, dyeing is particularly difficult to occur, and not only the density of the recorded image is low, but also the fading is significantly reduced over time. For this reason, an image receiving paper in which an image receiving layer mainly composed of a thermoplastic resin is provided on plain paper has been proposed, and various improvements in recording sensitivity, resolution, sharpness, color density and the like have been studied. Also, the use of plain paper is possible in principle for the transfer material of the hot melt transfer method, but defects such as uneven transfer and missing dots are likely to occur due to the smoothness of the transfer surface and ink acceptability. It is a difficult point. Therefore, various image receiving materials have been studied in order to improve surface smoothness, ink transfer receptivity, fixing properties, gradation properties, sharpness, and the like. Here, as a support for these various image receiving media, a dedicated transfer material such as plain paper, synthetic paper, synthetic resin film, white base filled with white pigment or the like is used. Therefore, in this method, the transfer material capable of forming an image is limited to a dedicated paper or a resin sheet provided with an image receiving layer, so that the quality is insufficient for proof use requiring printed matter approximation. . In addition, a method for transferring a recorded image to any desired transfer support is also known. Japanese Patent Application Laid-Open No. 52-27642 describes a method in which a transfer layer is heated and adhered to an intermediate receptor, and then the adhered transferred material is transferred to a material to be transferred such as paper. It is not done.
[0008]
In addition, in order to improve the recording sensitivity, dot quality, and gradation reproducibility by improving the cushioning property of the image receiving sheet, for example, a technique for controlling the cushioning property by adding a plasticizer in the binder is known. ing. As an example of a plasticizer, it is possible to select and use various types from those listed in P1034 of Chemical Handbook Application (Japan Chemical Society). However, most of the generally known plasticizers have a molecular weight of several hundreds, and the cushioning properties can be satisfied by using these plasticizers, but the image receiving film is used for the transfer of the plasticizer onto the surface of the image receiving layer. -There has been a problem that the surface of the tape is very sticky, resulting in the occurrence of sticking and increased dust defects.
[0009]
As described above, various image-receiving sheet materials have been proposed as transfer materials for thermal transfer recording materials, but none of them is sufficient to obtain a multi-gradation high-quality color image by an area gradation-only pigment transfer method. Met. Specifically, it is inferior in recording sensitivity, dot quality, and gradation reproducibility. Especially when trying to increase the thermal recording sensitivity, the thermal bonding temperature of the image receiving layer is lowered and the tackiness is increased, and sticking due to stickiness is generated and recorded. A problem arises in the adhesion resistance in the later image storage, and dust defects further increase. Further, when used as a color proof for color proofing, there is a big problem in the approximation of printed matter such as reproduction of texture of printing paper.
[0010]
[Problems to be solved by the invention]
The object of the present invention is to remedy the above drawbacks. In other words, a pigment transfer system with only area gradation, excellent recording sensitivity, dot quality, and gradation reproducibility, especially the formation of multi-gradation high-quality color images without stickiness on the surface of the image receiving sheet and associated dust defects. The present invention provides a transfer image forming method and an image receiving sheet material for thermal transfer recording that can achieve the above. Further, the present invention provides an image receiving sheet material for thermal transfer recording and a transfer image forming method, which can be transferred to printing paper and has excellent printed matter approximation such as reproduction of texture of printing paper and gloss of images.
[0011]
[Means for Solving the Problems]
  The purpose of the present invention is to
(1) An image receiving sheet material used for forming a transfer image in which an ink layer is thermally transferred from a transfer material having a heat transferable ink layer to an image receiving sheet material and then retransferred to a permanent support, wherein the image receiving sheet material is a support Having at least two image-receiving layers thereon, at least one of the image-receiving layers being transferred to a permanent support, the layer remaining on the support of the image-receiving sheet containing a plasticizer having a molecular weight of 1000 or more, and Young's modulus 10kgf · cm at room temperature^-2To 10,000kgf · cm^-2In the rangeAnd the plasticizer is at least one selected from the group consisting of polyfunctional acrylate monomers, urethane oligomers and polyester plasticizersAn image receiving sheet material, and
(2) 30 to 70 parts by weight of pigment provided on the support, 25 to 60 parts by weight of an amorphous organic polymer having a softening point of 40 to 150 ° C., and a film thickness of 0.2 μm to A heat transferable ink layer having a thickness of 1.0 μm is adhered to the image receiving sheet material described in (1) above, and an ink image is formed on the image receiving sheet material by thermal transfer, and then the ink image and at least one layer of the image receiving image are received. A transfer image forming method characterized in that the layer is transferred onto a permanent support.
  Hereinafter, the present invention will be described in detail.
[0012]
As the support for the image receiving sheet, a chemically and thermally stable material having flexibility is used. It may be actinic light transmissive as required. Specifically, polyolefins such as polyethylene and polypropylene, polyhalogenated vinyls such as polyvinyl chloride and polyvinylidene chloride, cellulose derivatives such as cellulose acetate, nitrocellulose and cellophane, polyamides, polystyrene, polycarbonate, polyimides, In some cases, a paper laminated with a polyethylene film can also be used. Among these, particularly preferred are biaxially stretched polyethylene phthalate films excellent in dimensional stability and permeability, but are not limited thereto.
[0013]
At least two image receiving layers are provided on the support, preferably from a layer in contact with the support (hereinafter referred to as “image receiving single layer”) and a layer provided thereon (hereinafter referred to as “image receiving two layers”). It is preferable to become.
In order to increase the adhesion between the support and the image receiving layer, it is possible to provide a surface treatment such as corona discharge treatment or glow discharge treatment, or an undercoat layer. Any undercoat layer may be used as long as it can increase the adhesion between the support and the image receiving layer, and a silane coupling agent is particularly suitable.
[0014]
  Next, the image receiving layer will be described. The Young's modulus of the image receiving layer is 10 kg · f / cm at room temperature.²To 10,000kg ・ f / cm²The following is preferable. This is because the use of a polymer having a low Young's modulus causes cushioning in the image receiving layer, thereby improving recording sensitivity, dot quality, and gradation reproducibility. Further, even when foreign matter such as dust is present between the heat-sensitive recording material and the image receiving sheet material during recording, there is an advantage that the image receiving layer is more cushioning and the image defect is less likely to occur. Also, after transferring the image to the image-receiving sheet material, the layer is embedded according to the unevenness of the paper when it is re-transferred with heat and pressure onto printing paper such as paper.Be turnedTherefore, it is possible to obtain an image whose surface gloss is close to that of a printed matter without special treatment such as matting of the surface after the two image-receiving layers are peeled off, with good adhesion to paper. Particularly preferred Young's modulus is 10 kg · f / cm at room temperature.²To 200kg ・ f / cm²Within this range, the film thickness of the first layer is suppressed to 50 μm or less, which is advantageous during production coating. The Young's modulus value is 10 kg · f / cm.²If it is smaller, there is a problem that it is very difficult to handle due to the adhesiveness during the production of the coating. Young's modulus is 10,000 kg · f / cm²In the above case, since the cushioning property of the image receiving layer is small, there arises a problem that the film thickness is inevitably increased in order to supplement the cushioning property by the film thickness, and the suitability for production is lost.
[0015]
Specific examples of materials include polyolefins such as polyethylene and polypropylene, ethylene copolymers such as ethylene and vinyl acetate or ethylene and acrylate, polyvinyl chloride, vinyl chloride copolymers such as vinyl chloride and vinyl acetate, and polychlorinated. At least one selected from organic polymer substances such as vinylidene, vinylidene chloride copolymer, poly (meth) acrylic acid ester, copolymerized nylon, polyamide resin such as N-alkoxymethylated nylon, synthetic rubber, and chlorinated rubber. preferable. Of these, polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate, copolymers of vinyl chloride and vinyl alcohol, copolymers of vinyl chloride, vinyl acetate and maleic acid, etc. with a degree of polymerization of 200-2000, among others Is particularly preferred. The reasons for this are that polyvinyl chloride and vinyl chloride copolymer are (1) almost no stickiness at room temperature, (2) have a relatively low elastic modulus, and can easily follow the irregularities of the transferred image during thermal transfer, (3) Abundant plasticizers with good compatibility and easy control of substantial elastic modulus; (4) Easy control of interlayer adhesion due to the effect of hydroxyl groups or carboxyl groups in the copolymer component; Etc. Of course, various polymers, adhesion improvers, surfactants, and release agents may be added to these organic polymers in order to adjust the adhesion between the image receiving sheet support and the image receiving two layers. For the purpose of lowering the elastic modulus, it is also very effective to use a part of the adhesive polymer within a range in which the adhesiveness at normal temperature does not occur.
[0016]
When vinyl chloride resin is used, organic tin stabilizers such as butyltin stabilizer or octyltin stabilizer, which are generally known as stabilizers for polyvinyl chloride and vinyl chloride copolymers, should be added. Is also effective.
[0017]
In the various binders, since Young's modulus is large by itself, the cushioning property is insufficient, and a plasticizer or the like is added to supplement the cushioning property. Examples of plasticizers having a molecular weight of 1000 or more and difficult to migrate onto the surface of the image receiving sheet include polyfunctional acrylic monomers and urethane oligomers as polyester plasticizers and monomer plasticizers. is there. Examples of polyester plasticizers include adipic acid, phthalic acid, sebacic acid, epoxy, trimellitic acid, pyromellitic acid, sebacic acid, citric acid, etc. Agents, phthalic acid plasticizers, and sebacic acid plasticizers are preferred. As the polyfunctional acrylate monomer, the following 6-functional acrylic monomers and dimethacrylates can be suitably used.
[0018]
[Chemical 1]

[0019]
As examples of urethane oligomers, polymers of general isocyanates and polyetherdiols or polyesterdiols can be used. Aromatic urethane acrylates and aliphatic urethanes can be used. The use of acrylate oligomers is preferred.
[0020]
Furthermore, other examples of preferable plasticizers include copolymers of ethylene groups and carboxylic acid vinyl ester groups and copolymers containing ethylene groups and acrylate groups. Examples of carboxylic acids include saturated aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, and stearic acid, and other examples include unsaturated fatty acids, carbocyclic carboxylic acids, and heterocyclic carboxylic acids. Examples of acrylic esters include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate hexyl methacrylate, decyloctyl methacrylate, lauryl methacrylate, Examples include stearyl methacrylate, dimethylaminoethyl methacrylate, and methacrylamide. Moreover, as a component of a copolymer, it can be made into a multi-component system suitably according to the intended purpose.
[0021]
The effect of the present invention is produced only when the plasticizer has a molecular weight of 1000 or more and has good cushioning properties. When the molecular weight is smaller than this, the plasticizer easily migrates on the surface of the image receiving sheet, increasing the stickiness on the surface of the image receiving sheet and causing problems such as sticking and dust defects. Also, it is not necessary that the molecular weight is large, and compatibility with the binder is important. If the molecular weight is large, it becomes difficult to be compatible with various binders or the cushioning property is inferior, so the film thickness must be increased. The problem of not becoming.
[0022]
The molecular weight of the plasticizer to be added is preferably 5000 or less, but even if the molecular weight is 5000 or more, the Young's modulus of the layer is 10 to 10,000 kg · f / cm.²If it falls within the range, it is not necessary to have a molecular weight within this range.
[0023]
If necessary, if acrylic rubber or linear polyurethane is added as an auxiliary binder to the cushioning layer such as the image receiving layer, the amount of plasticizer added can be reduced, and bleeding of the plasticizer on the surface can be reduced. Therefore, it is possible to prevent deterioration of adhesion resistance due to dust defects and deterioration of surface tackiness.
[0024]
The thickness of the organic polymer material in the image receiving layer is preferably 1 μm to 50 μm, particularly preferably 5 μm to 30 μm. One of the reasons is that when the image transferred on the image receiving sheet material is transferred to the permanent support, it is necessary to make it thicker than the irregularities on the surface of the permanent support, and the second reason is that four color images are used. This is because a thickness that can sufficiently absorb the relief step of the overlapping portion is necessary. A third reason is to obtain a sufficient cushioning property.
[0025]
Next, the two image receiving layers provided on this will be described. The purpose of the image-receiving two layers is to peel off the image-receiving sheet material during retransfer to the permanent support, causing delamination between the image-receiving layer and the image-receiving two layers, leaving only two thin image-receiving layers on the image on the permanent support. The object is to obtain an image approximating the gloss of the actual printed matter without applying a special matting treatment due to the unevenness of the permanent support. A second object is to improve the scratch resistance of the image.
Various materials can be basically used as the material for the image receiving double layer, but as the organic polymer material constituting the image receiving double layer, a polyvinyl butyral resin and a polymer compound having the following general formula (1) as a repeating unit are contained. It is preferable to do.
General formula (1)
[0026]
[Chemical 2]

[0027]
The polymer compound of the general formula (1) is obtained by polymerizing the monomer represented by the general formula (2) in a suitable solvent or without solvent in the presence of a polymerization initiator according to a conventional method, or co-polymerizing with other monomers. It is obtained by polymerizing.
General formula (2)
[0028]
[Chemical 3]

[0029]
In the case where A in the general formula (2) is a substituent having an amide bond, for example, CONHR₂, CONR₂R_ThreeIs mentioned. R₂, R_ThreeAre each independently hydrogen, an alkyl group having 1 to 18 carbon atoms, or an aryl group having 6 to 20 carbon atoms (the alkyl or aryl group is a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, a halogen, or a cyano group. One or more, and a combination of two or more thereof), R₂And R_ThreeIs bonded to alkylene having 1 to 20 carbon atoms and aralkylene (the alkylene and aralkylene may have a branch, and include an ether bond, —OCO—, —COO—, and combinations of two or more thereof) In addition, when A is a nitrogen-containing heterocycle, imidazoles, pyrrolidones, pyridines, carbazoles and the like can be mentioned. These include an alkyl group having 1 to 5 carbon atoms and an aryl group having 6 to 10 carbon atoms. , A halogen, a cyano group, and a combination of two or more thereof.
[0030]
A more preferable range of A in the general formula (1) is CONHR in the case of a substituent having an amide bond.₂', CONR₂'R_Three'； R₂', R_ThreeEach independently represents hydrogen, or an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 15 carbon atoms (the alkyl or aryl group is an alkoxy group having 1 to 6 hydroxy carbon atoms), and A represents a nitrogen-containing heterocycle In the case, imidazoles and triazoles may be mentioned, and they may be substituted with an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms.
[0031]
Specific examples of the general formula (1) include (meth) acrylamide, N-alkyl (meth) acrylamide (the alkyl group includes, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, and a heptyl group. , Octyl group, ethylhexyl group, cyclohexyl group, hydroxyethyl group, benzyl group, etc.), N-aryl (meth) acrylamide (as the aryl group, for example, phenyl group, tolyl group, nitrophenyl group, naphthyl group, hydroxy group) Phenyl group, etc.), NN-dialkyl (meth) acrylamide (the alkyl group includes, for example, methyl group, ethyl group, butyl group, isobutyl group, ethylhexyl group, cyclohexyl group, etc.), NN- Diaryl (meth) acrylamide (the aryl group includes, for example, phenyl Group), N-methyl-N-phenyl (meth) acrylamide, N-hydroxyethyl-N-methyl (meth) acrylamide, N-2acetamidoethyl-N-acetyl (meth) acrylamide, N- (phenylsulfonyl) (Meth) acrylamide, N- (p-methylphenylsulfonyl) (meth) acrylamide, 2 and 3 and 4-hydroxyphenylacrylamide, (meth) acryloylmorpholine, 1-vinylimidazole, 1-vinyl-2-methylimidazole, 1 -Vinyltriazole, 1-vinyl-3,5-dimethylimidazole, vinylpyrrolidone, 4-vinylpyridine, vinylcarbazole and the like.
[0032]
Next, specific examples of other monomers copolymerizable with the monomer represented by the general formula (2) include (meth) acrylic acid esters, (meth) acrylamides, allyl compounds, vinyl ethers, vinyls. Examples thereof include compounds having a polymerizable unsaturated bond selected from esters, styrenes, crotonic acid esters and the like. Specifically, (meth) acrylic acid esters, for example, alkyl (meth) acrylate, or substituted (meth) alkyl acrylate (for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) ) Acrylate, butyl (meth) acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, t-octyl (meth) acrylate, chloroethyl (meth) ) Acrylate, allyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2,2-dimethyl Ru-3-hydroxypropyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, benzyl (meth) acrylate, methoxybenzyl (meth) acrylate, Chlorobenzyl (meth) acrylate, furfuryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), aryl (meth) acrylate (eg phenyl (meth) acrylate, cresyl (meth) acrylate, naphthyl) (Meth) acrylates), styrenes such as styrene, alkyl styrene (eg methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, Ethyl styrene, isopropyl styrene, butyl styrene, hexyl styrene, cyclohexyl styrene, decyl styrene, benzyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, etc.), alkoxy styrene (eg methoxy styrene, 4-methoxy -3-methylstyrene, dimethoxystyrene, etc.), halogenostyrene (for example, chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2- Bromo-4-trifluorostyrene, 4-fluoro-3-trifluoromethylstyrene, etc.), hydroxystyrene, etc .; There are rotonic acid esters, for example, alkyl crotonic acid (for example, butyl crotonic acid, hexyl crotonic acid, glycerin monocrotonate, etc.), (meth) acrylic acid, crotonic acid, itaconic acid, acrylonitrile.
[0033]
Preferable specific examples of the polymer having the repeating unit represented by the general formula (1) include N, N-dimethylacrylamide / butyl (meth) acrylate copolymer, N, N-dimethyl (meth). Acrylamide / 2-ethylhexyl (meth) acrylate copolymer, N, N-dimethyl (meth) acrylamide / hexyl (meth) acrylate copolymer, N-butyl (meth) acrylamide / butyl (meth) acrylate Copolymer, N-butyl (meth) acrylamide / 2-ethylhexyl (meth) acrylate copolymer, N-butyl (meth) acrylamide / hexyl (meth) acrylate copolymer, (meth) acryloylmorpholine / Butyl (meth) acrylate copolymer, (meth) acryloylmorpholine / 2-ethylhexyl (meth) Acrylate copolymer, (meth) acryloylmorpholine / hexyl (meth) acrylate copolymer, 1-vinyl imidazole / butyl (meth) acrylate copolymer, 1-vinyl imidazole / 2 -Ethylhexyl (meth) acrylate copolymer, 1-vinylimidazole / hexyl (meth) acrylate copolymer, and the like. Moreover, the preferable content rate of the unit of General formula (1) is 10-100 mol%, More preferably, it is 30-80 mol%. When the content of the unit of the general formula (1) is less than 10 mol%, the image quality is inferior. The preferred molecular weight range is 1000-200000, more preferably 2000-100000. If the molecular weight is less than 1,000, the production is difficult, and if it exceeds 200,000, the solubility in a solvent decreases.
[0034]
  There are various types of resins that can be used in combination with these resins. For example, polyolefins such as polyethylene and polypropylene, ethylene copolymers such as ethylene and vinyl acetate, ethylene and acrylate esters, ethylene and acrylic acid, polyvinyl chloride, and vinyl chloride. And vinyl chloride copolymer such as vinyl acetate, polyvinylidene chloride, vinylidene chloride copolymer, polystyrene, styrene copolymer such as styrene and maleate esterBody, vinegarAcid vinyl copolymer, butyral resin, modified polyvinyl alcohol, copolymer nylon, polyamide resin such as N-alkoxymethylated nylon, synthetic rubber, chlorinated rubber, phenol resin, epoxy resin, urethane resin, urea resin, melamine resin Alkyd resin, maleic acid resin, hydroxystyrene copolymer, sulfonamide resin, ester gum, cellulose resin, rosin, and the like.
[0035]
The compound of the general formula (1) added to these resins is preferably 5 to 50% by weight, and if it is added more than this, the surface of the image receiving bilayer will be sticky and hinder handling. A particularly preferred range is 10 to 30% by weight.
[0036]
Further, it is natural that other adhesion improvers, mold release agents, plasticizers, surfactants, and the like can be added to these resins in order to satisfy the relationship of adhesive strength at various interfaces. The coating solvent used for the image receiving two layers is a coating solvent that does not dissolve or swell the resin used in the image receiving layer for the purpose of preventing mixing of the image receiving layer and the image receiving two layers due to penetration of the coating solvent into the lower layer during coating. It is necessary to use it. For example, when a vinyl chloride resin having relatively good solubility in various solvents is used for the image receiving layer, it is preferable to use an alcohol-based or water-based coating solvent. The film thickness of the image receiving two layers is preferably 0.1 μm to 10 μm, particularly preferably 0.5 μm to 5 μm. If the film thickness is too thick, the surface roughness of the permanent support will be impaired, and the gloss will be too high, resulting in poor print approximation.
[0037]
In order to cause delamination between the organic polymer substance of the image receiving layer and the organic polymer substance of the two image receiving layers by peeling of the image receiving sheet material during transfer to the permanent support, the balance of adhesion between each layer is important. However, in order to prevent mixing at the time of multilayer coating used in the present invention in controlling interlayer adhesion, in addition to selection of a coating solvent, a material such as a combination of a hydrophilic polymer and a lipophilic polymer or a combination of a polar polymer and a nonpolar polymer is used. It is effective to add an adhesion improving agent such as a silane coupling agent, various additives having fluorine or silicone release curing, a surfactant, a plasticizer, etc. to the image receiving layer or the image receiving layer. .
[0038]
An intermediate layer may be provided between the image receiving layer and the image receiving two layers for the purpose of adjusting transferability.
[0039]
Next, a transfer material (hereinafter referred to as “thermal transfer sheet”) having a heat-transferable ink layer useful for the present invention will be described.
[0040]
As the support of the thermal transfer sheet, various known supports are used as a conventional support for melt transfer or sublimation transfer, but a release treatment is performed on the back surface having a thickness of about 5 μm as in the case of an ordinary thermal head transfer photosensitive material. A polyester film subjected to is particularly preferred.
[0041]
  Thermal transferSheetVarious known pigments can be used as the pigment contained in the ink layer, and examples thereof include carbon black, azo, phthalocyanine, quinacridone, thioindigo, anthraquinone, and isoindoline pigments. Two or more of these may be used in combination, and a known dye may be added for hue adjustment.
[0042]
Examples of the amorphous organic polymer conjugate having a softening point of 50 ° C. to 150 ° C. contained in the ink layer of the thermal transfer sheet include, for example, butyral resin, polyamide resin, polyethyleneimine resin, sulfonamide resin, polyester polyol resin, and petroleum resin. Styrene, vinyl toluene, α-methyl styrene, 2-methyl styrene, chloro styrene, vinyl benzoic acid, vinyl benzene sulfonic acid soda, aminostyrene, and other styrenes and their derivatives, substituted homopolymers and copolymers, methyl Methacrylic acid esters such as methacrylate, ethyl methacrylate, butyl methacrylate and hydroxyethyl methacrylate, and acrylic acid esters such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate and α-ethylhexyl acrylate And dienes such as acrylic acid, butadiene and isoprene, acrylonitrile, vinyl ethers, maleic acid and maleic esters, maleic anhydride, cinnamic acid, vinyl chloride, vinyl acetate alone or other A copolymer with a monomer or the like can be used.
These resins can be used in combination of two or more.
[0043]
Of these, a butyral resin and a styrene / maleic acid half ester resin are particularly preferred from the viewpoint of dispersibility, which is a feature of the present invention described later. The softening point of these resins should be selected in the range of 40 ° C to 150 ° C. If it exceeds 150 ° C., the thermal recording sensitivity is low, and if it is less than 40 ° C., the adhesion resistance of the ink layer is poor.
[0044]
  In these ink layers, various releasing agents and softening agents are added in an amount of 1 to 20% by weight with respect to the total amount of the ink layer from the viewpoint of releasing the ink layer from the support during thermal printing and improving thermal sensitivity. It is also possible to add within the range. Specifically, for example, higher fatty acids such as palmitic acid and stearic acid, fatty acid metal salts such as zinc stearate, fatty acid esters or partially saponified products thereof, fatty acid derivatives such as fatty acid amides, higher alcohols, polyhydric alcohols ofesterEquivalent derivatives, waxes such as paraffin wax, carnauba wax, montan wax, beeswax, wood wax, candelilla wax, polyolefins such as low molecular weight polyethylene having a viscosity average molecular weight of about 1,000 to about 10,000, polypropylene, polybutylene, etc. Or low molecular weight copolymers of olefin, α-olefins and organic acids such as maleic anhydride, acrylic acid and methacrylic acid, vinyl acetate, low molecular weight oxidized polyolefins, halogenated polyolefins, lauryl methacrylate, stearyl methacrylate Methacrylic acid ester having an equal-length alkyl side chain, acrylic acid ester or acrylic acid ester having a perfluoro group, methacrylic acid ester alone or a copolymer with a vinyl monomer such as styrene, Low molecular weight silicone resins such as siloxane, polydiphenylsiloxane, and silicone-modified organic substances, as well as cationic surfactants such as ammonium salts and pyridinium salts having long chain aliphatic groups, or similarly long chain aliphatic groups One or more types selected from an anion having a nonionic surfactant, a nonionic surfactant, a perfluorosurfactant and the like can be used.
[0045]
The optical density of these thermally transferable ink layers must have a reflection density of 1.0 or more when thermally transferred onto a white support for the reasons described above.
The film thickness is preferably in the range of 0.2 μm to 1.0 μm. In a thick ink layer larger than 1.0 μm, in the gradation reproducibility by only area gradation, the shadow part is easily crushed and the highlight part is easy to fly, resulting in poor gradation reproducibility. Become. On the other hand, when the film thickness is less than 0.2 μm, it is difficult to obtain a predetermined concentration.
[0046]
In order to obtain a predetermined concentration with these thin films, the pigment is added in an amount of 30 to 70 parts by weight of the pigment and 25 to 60 parts by weight of the amorphous organic polymer conjugate as needed. It is preferable that the total amount of the releasable substance and the softener is 1 to 15 parts by weight.
If the pigment ratio is less than this, it is difficult to obtain a predetermined concentration with the predetermined film thickness.
Further, the particle size of the pigment needs to be 70 μm or more and 1.0 μm or less. When the particle size is large, the transparency of the overlapping portion of each color at the time of color reproduction is impaired, and it becomes difficult to satisfy both the relationship between the film thickness and the density.
[0047]
With respect to the dispersion of these pigments into the amorphous organic polymer conjugate, various dispersion methods used in the paint field such as a ball mill are applied by adding an appropriate solvent.
[0048]
The heat transferable ink layer is mainly composed of a pigment and an amorphous organic polymer combination, and has a higher pigment ratio than the conventional wax melt type, and has a viscosity at the time of thermal transfer of 10 compared to the normal melt type.²-10^ThreeIt is not as low as cps, and at 10^FourSince it is higher than cps, it can be said that the present invention is image formation of a thin film peeling development type utilizing thermal adhesiveness of a receiving sheet or thermal adhesiveness between ink layers in the case of color image formation. This combined with the effect of thinning the ink layer, while maintaining high resolving power, enables a wide gradation reproduction from the shadow part to the highlight part, and improves the edge sharpness, Furthermore, by making it possible to transfer an image of 100%, for example, the uniformity of the density of small characters of 4 points and solid portions was realized.
[0049]
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.
[0050]
【Example】
Synthesis example 1
<Synthesis of polymer compound (a)>
170 parts of propylene glycol monomethyl ether was heated and stirred under a nitrogen stream at 80 ° C., 0.07 part of 2,2′-azobis (2,4-dimethylvaleronitrile) was added and stirred for 30 minutes. To this, 31.6 parts of butyl acrylate, 24.4 parts of N, N-dimethylacrylamide, and 0.07 part of 2,2'-azobis (2,4-dimethylvaleronitrile) were appropriately applied over 30 minutes. 30 minutes and 1 hour after the completion of the dropwise addition, 0.15 part of 2,2′-azobis (2,4-dimethylvaleronitrile) was further added, and the mixture was further heated and stirred for 4 hours. A 28% propylene glycol monomethyl ether solution was obtained. The weight average molecular weight was 13000 (polystyrene conversion).
[0051]
Example 1
(Creation of image receiving sheet)
A coating solution for one image receiving layer and two image receiving layers having the following composition was prepared.

[0052]

[0053]
A polyethylene terephthalate (PET) film having a thickness of 100 μm is coated on the support using the spin coater (hoera) at 300 rpm, and in an oven at 100 ° C. Dried for 2 minutes. The film thickness of the obtained image receiving layer was 20 μm.
[0054]
On the image receiving layer, the image receiving double layer coating solution was applied at 200 rpm using a spin coater (Wheeler) and dried in an oven at 100 ° C. for 2 minutes. The film thickness of the obtained image receiving bilayer was 2 μm.
[0055]
(Creation of thermal transfer sheet)
Next, the following three ink layer coating solutions were prepared.

[0056]
0.24 parts by weight of stearamide and 60 parts by weight of n-propyl alcohol were added to 10 parts by weight of each of the A, B, and C pigment dispersions to form a coating solution, and the release treatment was performed on the back surface having a thickness of 5 μm. A thermal transfer sheet was prepared by applying a polyester film (manufactured by Teijin Ltd.) so that the dry film thickness A was 0.36 μm, B was 0.38 μm, and C was 0.42 μm.
[0057]
First, a cyan thermal transfer sheet and an image receiving sheet were overlapped, and printing was performed by a thermal head recording apparatus (prototype experimental machine) based on the sub-scanning division method. This principle is a system in which multi-step modulation of only area gradation is performed by turning on and off a 75 μm × 50 μm head in a 50 μm direction with a minute feed of 3 μm pitch.
The cyan thermal transfer sheet was peeled off to form an image having only area gradation on the image receiving sheet. Next, the magenta thermal transfer sheet is overlaid on the image receiving sheet on which the cyan image is formed, aligned and printed in the same manner, and the transfer sheet is peeled off to peel off the magenta image on the image receiving sheet. Similarly, a yellow image was formed to form a color image consisting only of area gradations on the image receiving sheet. Next, the image receiving sheet on which the color image is formed is overlapped with the sheet paper, passed through a 4 m / sec thermal roller at 130 ° C. and a pressure of 4.5 kg / cm, and then the image receiving sheet. The polyester film was peeled off, and the two image receiving layers on which the ink image was placed were transferred, and color images were formed on the art paper. This color image had a very good approximation between the color image and a chemical proof produced by a lith manuscript (manufactured by Fuji Photo Film Co., Ltd., product name Color Art). At this time, the reflection density of each single color was as follows.

When the density of the 4P characters was measured with a microdensitometer, it was the same as the density of the solid part.
[0058]
The tone reproducibility was 5% to 95%, which was very good. Furthermore, there is no stickiness on the surface of the image receiving sheet, no defect due to dust, the dot shape is good, the surface is matted following the unevenness of the paper, and the surface gloss is very close to the printed matter. It was.
[0059]
Example 2
(Creation of image receiving sheet)
A coating solution for one image receiving layer and two image receiving layers having the following composition was prepared.

[0060]

[0061]
An image receiving sheet was prepared in the same manner as in Example 1 using the coating solution. Using the obtained image receiving sheet and a thermal transfer sheet prepared in the same manner as in Example 1, color images were formed in the same manner as in Example 1, and the images were evaluated. The evaluation results are shown in Table 1.
[0062]
Example 3
The same procedure as in Example 1 was performed except that an aromatic urethane oligomer (EB-6600, molecular weight 1598, manufactured by Daicel Usbi Co., Ltd.) was used instead of DPCA-120 in the image receiving layer of Example 1. An image receiving sheet was prepared. Using this image receiving sheet, a color image was formed in the same manner as in Example 1 and the image was evaluated. The evaluation results are shown in Table 1.
[0063]
Example 4
In the same manner as in Example 1 except that urethane oligomer (U-2001BA-23, molecular weight 4260, manufactured by Shin-Nakamura Chemical Co., Ltd.) was used instead of DPCA-120 in the image-receiving layer of Example 1. Created. Using this image receiving sheet, a color image was formed in the same manner as in Example 1 and the image was evaluated. The evaluation results are shown in Table 1.
[0064]
Example 5
In Example 1, the plasticizer DPCA-120 added to the image receiving layer was changed to 9 parts by weight, and 3 parts by weight of acrylic rubber (RS-08, manufactured by Nissin Chemical Industry Co., Ltd.) was added as an auxiliary binder. An image receiving sheet was prepared in the same manner as in Example 1. Using this image receiving sheet, a color image was formed in the same manner as in Example 1 and the image was evaluated. The evaluation results are shown in Table 2.
[0065]
Example 6
In Example 1, the plasticizer DPCA-120 added to the image receiving layer was changed to 9 parts by weight, and 3 parts by weight of linear polyurethane (Desmocol 406, manufactured by Sumitomo Biurethane Co., Ltd.) was added as an auxiliary binder. An image receiving sheet was prepared in the same manner as in Example 1 except for the above. Using this image receiving sheet, a color image was formed in the same manner as in Example 1 and the image was evaluated. The evaluation results are shown in Table 2.
[0066]
Example 7
Example 1 is the same as Example 1 except that the plasticizer DPCA-120 added to the image receiving layer is changed to 12 parts by weight of a polyester plasticizer (Paraplex G-25, molecular weight 8000, manufactured by Rohm and Haas Japan). An image receiving sheet was prepared. Using this image receiving sheet, a color image was formed in the same manner as in Example 1 and the image was evaluated. The evaluation results are shown in Table 2.
[0070]
Example8
  An ethylene-acrylic acid ester-polar monomer copolymer (Elvalloy L742, molecular weight of 250,000 or more, manufactured by Mitsui-Deupon Polychemical Co., Ltd.) was used instead of the image-receiving single-layer vinyl chloride vinyl acetate copolymer of Example 1 and DPCA-120. An image receiving sheet was prepared in the same manner as in Example 1 except that 2 parts by weight of polyester plasticizer W-20 (Dainippon Ink Chemical Co., Ltd.) was added. Using this image receiving sheet, a color image was formed in the same manner as in Example 1 and the image was evaluated. The evaluation results are shown in Table 3.
[0071]
Comparative Example 1
An image receiving sheet was prepared in the same manner as in Example 1 except that TPP (regular phosphate ester plasticizer, manufactured by Daihachi Chemical Co., Ltd., molecular weight 326) was used instead of DPCA-120 in the image receiving layer of Example 1. Created. A color image was formed using this image receiving sheet in the same manner as in Example 1. However, the surface was very sticky, there were many dust defects, the dot shape was poor, and the reproduction gradation was inferior.
[0072]
Comparative Example 2
Except for using tetramethylol methane tetraacrylate (tetrafunctional acrylic monomer, trade name A-TMMT, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 352) instead of DPCA-120 of the image receiving layer of Example 1. Was the same as in Example 1 to prepare an image receiving sheet. Using this image receiving sheet, a color image was formed in the same manner as in Example 1. However, the surface was very sticky, there were many dust defects, and the dot shape was poor and handling was very poor.
[0073]
Comparative Example 3
An image receiving sheet was prepared in the same manner as in Example 1 except that DPCA-120 of the first image receiving layer in Example 1 was omitted. When a color image was formed using this image receiving sheet in the same manner as in Example 1, there was no surface stickiness, but there were many dust defects and the dot shape was poor and the gradation was poor.
[0074]
Comparative Example 4
An image receiving sheet was prepared in the same manner as in Example 1 except that urethane oligomer (U-340AX, molecular weight 12000, manufactured by Shin-Nakamura Chemical Co., Ltd.) was used instead of DPCA-120 of the image receiving layer of Example 1. Created. Using this image receiving sheet, a color image was formed in the same manner as in Example 1 and the image was evaluated. The evaluation results are shown in Table 1.
[0075]

[0076]

[0077]
[Table 1]

[0078]
【The invention's effect】
The image receiving sheet material and the transfer image forming method of the present invention are excellent in recording sensitivity, dot quality, gradation, and particularly in printed matter approximation without causing stickiness or sticking on the surface of the image receiving sheet. Images can be obtained.

Claims (2)

An image receiving sheet material used to form a transfer image in which an ink layer is thermally transferred from a transfer material having a thermally transferable ink layer to an image receiving sheet material and then retransferred to a permanent support, wherein the image receiving sheet material is at least on the support. It has two image receiving layers, at least one of the image receiving layers is transferred to a permanent support, the layer remaining on the image receiving sheet support contains a plasticizer having a molecular weight of 1000 or more, and the Young's modulus is room temperature. range near the 10000 kgf · ^{cm -2} from 10 kgf · ^{cm -2} is, and that the plasticizer is at least one selected from the group consisting of polyfunctional acrylate monomers, urethane oligomer and polyester plasticizer An image receiving sheet material characterized by 30 to 70 parts by weight of pigment provided on the support, 25 to 60 parts by weight of an amorphous organic polymer having a softening point of 40 to 150 ° C., and a film thickness of 0.2 μm to 1.0 μm A heat-transferable ink layer is adhered to the image-receiving sheet material according to claim 1, an ink image is formed on the image-receiving sheet material by thermal transfer, and then the ink image and at least one image-receiving layer are permanently supported. A transfer image forming method, wherein the transfer image is transferred to the top.