JP4170470B2 - Thermal transfer sheet - Google Patents

Description

尚、ｎは１以上の整数を示す。
【化２】

【００１４】
上記の脂環族系石油樹脂は、軟化点が８０〜１４０℃の範囲内であるものが好ましく用いられ、該石油樹脂の溶融粘度が他の樹脂に比較して低いため、ワックスインキ中に多量に添加しても溶融粘度を低く抑えられる。
また熱溶融インキ層は該硬い石油樹脂が、軟らかいワックスに添加されているため、印字に転写感度と印字物の耐擦過性の双方において優れたものとなる。
次に、脂環族・芳香族系石油樹脂は、脂環族系石油樹脂と芳香族系石油樹脂が混合されたもの（相互に分子結合はされていない。）である。
例えば、ビニル芳香族石油樹脂を主体とする重合体ブロックと、脂環構造の共役ジエンを主体とする重合体ブロックとのブロック共重合体等が挙げられる。
上記のビニル芳香族石油樹脂としては、例えば、スチレン、ビニルトルエン、ビニルナフタレン等が挙げられ、脂環構造の共役ジエンとしては、例えば、１，３−ヘキサジエン等が挙げられる。
上記の脂環族・芳香族系石油樹脂は、軟化点が８０〜１４０℃の範囲内であるものが好ましく用いられ、該石油樹脂の溶融粘度が他の樹脂に比較して低いため、ワックスインキ中に多量に添加しても溶融粘度を低く抑えられる。
また熱溶融インキ層は該硬い石油樹脂が、軟らかいワックスに添加されているため、印字の転写感度と印字物の耐擦過性の双方において優れたものとなる。
【００１５】
また、バインダー樹脂として、上記の石油樹脂に加えて、中密度ポリエチレン、高密度ポリエチレン、ポリプロピレン樹脂、ポリエステル樹脂、ポリアミド樹脂、アイオノマー樹脂、エチレン−アクリレート樹脂、スチレン−ブタジエン共重合体、アクリロニトリル−ブタジエン共重合体、ポリスチレン樹脂等の比較的軟化点の低い熱可塑性樹脂が使用できる。
熱溶融インキ層で使用するワックスとしては、ワックスとしては、例えば、マイクロクリスタリンワックス、カルナバワックス、パラフィンワックス、フィッシャートロプシュワックス、各種低分子量ポリエチレン、木ロウ、ミツロウ、鯨ロウ、イボタロウ、羊毛ロウ、セラックワックス、キャンデリラワックス、ペトロラクタム、ポリエステルワックス、一部変性ワックス、脂肪酸エステル、脂肪酸アミド等、種々のワックスが挙げられる。
【００１６】
上記のワックスの中でも、針入度が４以上で、融点の低めのワックスを主成分として、熱溶融インキとして、ホットメルト塗工が行いやすく、また印字の感度を高めることが好ましい。針入度が４以上のワックスとして、具体的にはパラフィンワックス、マイクロクリスタリンワックス等、針入度が４以上であれば、上記の各種ワックスが使用できる。一般的に、針入度１０以上のワックスを使用するのが望ましい。また、使用するワックスの針入度の上限としては、３０程度、好ましくは２０程度である。
熱溶融インキ層中のワックス含有量は、熱溶融インキ層の全固形分に対して４０〜７０重量％程度である。
また、本発明では、着色剤として、イエロー、マゼンタ、シアン、ブラック、ホワイトなどの各着色剤が、従来公知の染料、顔料より適宜選択可能である。
本発明の熱溶融インキ層の塗工液には、上記のバインダー樹脂と着色剤と、必要に応じて可塑剤、界面活性剤、滑剤、流動性調整剤等の助剤を加えることもできる。
【００１７】
熱溶融インキ層の形成は、上記材料で配合した熱溶融インキ層形成用塗布液を、従来公知の塗工手段、例えばホットメルトコート、ホットラッカーコート、グラビアダイレクトコート、グラビアリバースコート、ナイフコート、エアコート、ロールコート等の方法により行うことができる。
本発明の熱転写シートでは、熱溶融インキ層にワックスとして針入度が４以上で、融点の低いワックスを使用することが望ましく、ホットメルトコートによる熱溶融インキ層の形成が好ましく行われる。
熱溶融インキ層の厚さは、乾燥状態で、０．５〜６μｍ程度が好ましい。０．５μｍ未満では、充分な着色性が得られず、６μｍを越えると多量の印字エネルギーが必要となり好ましくない。
【００１８】
（接着層）
本発明の熱転写シートは、熱溶融インキ層の上に接着層を設けることが可能である。接着層は、受像シートと転写される熱溶融インキ層との接着性を向上させることができる。
この接着層は、サーマルヘッド、レーザー等の加熱により、軟化して接着性を発揮する熱可塑性樹脂を主体とし、得られる熱転写シートをロール状に巻き取った時にブロッキングを防止するために、ワックス類、高級脂肪酸のアミド、エステル及び塩、フッ素樹脂や無機物質の粉末のようにブロッキング防止剤を添加することができる。
【００１９】
熱可塑性樹脂として、例えば、エチレン−酢酸ビニル共重合体（ＥＶＡ）、エチレン−アクリル酸エステル共重合体（ＥＥＡ）、ポリエステル樹脂、ポリエチレン、ポリスチレン、ポリプロピレン、ポリブデン、石油樹脂、塩化ビニル樹脂、塩化ビニル−酢酸ビニル共重合体、ポリビニルアルコール、塩化ビニリデン樹脂、メタクリル樹脂、ポリアミド、ポリカーボネート、ポリビニルフォルマール、ポリビニルブチラール、アセチルセルロース、ニトロセルロース、ポリ酢酸ビニル、ポリイソブチレン、エチルセルロースまたはポリアセタールなどが挙げられ、特に従来感熱接着剤として使用されている比較的低軟化点、例えば、５０〜１５０℃の軟化点を有するものが好ましい。
【００２０】
接着層の形成は、上記の熱可塑性樹脂と添加剤をホットメルトコートまたは適当な有機溶剤または水に溶解または分散した接着層形成用塗工液を、従来公知のホットメルトコート、ホットラッカーコート、グラビアダイレクトコート、グラビアリバースコート、ナイフコート、エアコート、ロールコート等の方法により、乾燥状態で厚さ０．０５〜５μｍを設けるものである。
乾燥塗膜の厚さが、０．０５μｍ未満の場合、受像シート及び熱溶融インキ層との接着性が劣り、印字の際に転写不良となる。また、厚さが５μｍを越えた場合、印字時の転写感度が低下し、満足のいく印字品質が得られない。
【００２１】
（耐熱層）
また、本発明においては、基材フィルムとして熱に弱い材料を用いる場合、サーマルヘッドに接する側の表面に、サーマルヘッドの滑り性を良くし、かつスティッキングを防止する耐熱層を設けることが好ましい。耐熱層は、耐熱性のある樹脂と熱離型剤または滑剤の働きをする物質とを基本的な構成成分とする。
このような耐熱層を設けることによって、熱に弱いプラスチックフィルムを基材とした熱転写シートにおいてもスティッキングが起こることなく熱印字が可能であって、プラスチックフィルムの持つ切れにくさ、加工のし易さ等のメリットが生かせる。
【００２２】
この耐熱層は、バインダー樹脂に滑り剤、界面活性剤、無機粒子、有機粒子、顔料等を添加したものを、好適に使用し、形成される。
耐熱層に使用されるバインダー樹脂は、例えば、エチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、メチルセルロース、酢酸セルロース、酢酪酸セルロース、硝化綿などのセルロース系樹脂、ポリビニルアルコール、ポリ酢酸ビニル、ポリビニルブチラール、ポリビニルアセタール、ポリビニルピロリドン、アクリル樹脂、ポリアクリルアミド、アクリロニトリル−スチレン共重合体などのビニル系樹脂、ポリエステル樹脂、ポリウレタン樹脂、シリコーン変性またはフッ素変性ウレタン樹脂などが、あげられる。
【００２３】
これらのなかで、数個の反応性基、例えば、水酸基を有しているものを使用し、架橋剤として、ポリイソシアネートなどを併用して、架橋樹脂を使用することが好ましい。
耐熱層を形成する手段は、上記のごとき、バインダー樹脂に滑り剤、界面活性剤、無機粒子、有機粒子、顔料等を添加した材料を、適当な溶剤中に溶解または分散させて、塗工液を調製し、この塗工液をグラビアコーター、ロールコーター、ワイヤーバーなどの慣用の塗工手段により、塗工し、乾燥するものである。
【００２４】
【実施例】
次に実施例及び比較例をあげて、本発明を更に具体的に説明する。尚、文中、部又は％とあるのは、特に断りのない限り重量基準である。
（実施例１）
基材フィルムとして、厚さ４．５μｍのポリエチレンテレフタレートフィルム（東レ株式会社製、ルミラー）の一方の面に、下記組成の熱溶融インキ層塗工液１をホットメルトコートにより、乾燥塗布量が３．０ｇ／ｍ² になるように塗布、乾燥して熱溶融インキ層を形成し、実施例１の熱転写シートを作成する。
尚、上記の基材フィルムの他方の面に、予め下記組成の耐熱層塗工液をグラビアコーティングにより、乾燥塗布量が０．３ｇ／ｍ² になるように塗布、乾燥して、耐熱層を形成しておく。
【００２５】
熱溶融インキ層塗工液１
カーボンブラック（三菱化学株式会社製、＃４４） １５部
パラフィンワックス（針入度１１） ４０部
カルナバワックス １０部
脂環族・芳香族系石油樹脂 ３０部
（日本ゼオン株式会社製、Ｑｕｉｎｔｏｎｅ１９２５、軟化点１２５℃）
エチレン−酢酸ビニル共重合体 ５部
（ＭＩ＝１５０、ＶＡ＝１９％）
【００２６】
耐熱層塗工液
スチレンアクリロニトリル共重合体樹脂 １１部
線状飽和ポリエステル樹脂 ０．３部
ジンクステアリルホスフェート ６部
メラミン樹脂粉末 ３部
メチルエチルケトン ８０部
【００２７】
（実施例２）
上記の実施例１で使用した熱溶融インキ層塗工液１を、下記組成の塗工液２に変更し、その他は実施例１と同様にして、実施例２の熱転写シートを作成した。熱溶融インキ層塗工液２
カーボンブラック（三菱化学株式会社製、＃４４） １５部
パラフィンワックス（針入度１１） ５０部
カルナバワックス １０部
脂環族・芳香族系石油樹脂 ２０部
（日本ゼオン株式会社製、Ｑｕｉｎｔｏｎｅ１９２５、軟化点１２５℃）
エチレン−酢酸ビニル共重合体 ５部
（ＭＩ＝１５０、ＶＡ＝１９％）
【００２８】
（実施例３）
上記の実施例１で使用した熱溶融インキ層塗工液１を、下記組成の塗工液３に変更し、その他は実施例１と同様にして、実施例３の熱転写シートを作成した。熱溶融インキ層塗工液３
カーボンブラック（三菱化学株式会社製、＃４４） １５部
パラフィンワックス（針入度１１） ４０部
カルナバワックス １０部
脂環族系石油樹脂 ３０部
（日本ゼオン株式会社製、Ｑｕｉｎｔｏｎｅ１５００、軟化点１００℃）
エチレン−酢酸ビニル共重合体 ５部
（ＭＩ＝１５０、ＶＡ＝１９％）
【００２９】
（実施例４）
上記の実施例１で使用した熱溶融インキ層塗工液１を、下記組成の塗工液４に変更し、その他は実施例１と同様にして、実施例４の熱転写シートを作成した。熱溶融インキ層塗工液４
カーボンブラック（三菱化学株式会社製、＃４４） １５部
パラフィンワックス（針入度１３） ４０部
カルナバワックス １０部
脂環族・芳香族系石油樹脂 ３０部
（日本ゼオン株式会社製、Ｑｕｉｎｔｏｎｅ１９２５、軟化点１２５℃）
エチレン−酢酸ビニル共重合体 ５部
（ＭＩ＝１５０、ＶＡ＝１９％）
【００３０】
（比較例１）
上記の実施例１で使用した熱溶融インキ層塗工液１を、下記組成の塗工液５に変更し、その他は実施例１と同様にして、比較例１の熱転写シートを作成した。熱溶融インキ層塗工液５
カーボンブラック（三菱化学株式会社製、＃４４） １５部
パラフィンワックス（針入度１１） ６０部
カルナバワックス １０部
脂環族・芳香族系石油樹脂 １０部
（日本ゼオン株式会社製、Ｑｕｉｎｔｏｎｅ１９２５、軟化点１２５℃）
エチレン−酢酸ビニル共重合体 ５部
（ＭＩ＝１５０、ＶＡ＝１９％）
【００３１】
（比較例２）
上記の実施例１で使用した熱溶融インキ層塗工液１を、下記組成の塗工液６に変更し、その他は実施例１と同様にして、比較例２の熱転写シートを作成した。熱溶融インキ層塗工液６
カーボンブラック（三菱化学株式会社製、＃４４） １５部
パラフィンワックス（針入度１１） ４０部
カルナバワックス １０部
変性テルペン樹脂 ３０部
（ヤスハラケミカル株式会社製、Ｔ０１１５、軟化点１１５℃）
エチレン−酢酸ビニル共重合体 ５部
（ＭＩ＝１５０、ＶＡ＝１９％）
【００３２】
（比較例３）
上記の実施例１で使用した熱溶融インキ層塗工液１を、下記組成の塗工液７に変更し、その他は実施例１と同様にして、比較例３の熱転写シートを作成した。熱溶融インキ層塗工液７
カーボンブラック（三菱化学株式会社製、＃４４） １５部
パラフィンワックス（針入度１１） ４０部
カルナバワックス ４０部
エチレン−酢酸ビニル共重合体 ５部
（ＭＩ＝１５０、ＶＡ＝１９％）
【００３３】
上記、実施例および比較例の熱転写シートを用いて、下記の印字条件にて、印字を実施し、その印字物を下記の評価方法にて、印字品質及び耐擦過性の評価を行う。
印字条件
使用プリンターは、Ａｕｔｏｎｃｓ社製ＢＣ８ＭＫ３プリンターを用い、ミラーコート紙に印字速度４０ｍｍ／ｓｅｃの条件で、バーコードパターンを印字した。
印字品質の評価方法
上記の各印字物について、バーコードの転写状態を目視にて観察し、下記の判断基準にて評価する。
○：転写状態が良好である。
×：転写状態が不良である。
【００３４】
耐擦過性の評価方法
上記の各印字物について、下記の方法にて、擦過性テストを行い、印字物の表面状態を目視にて観察し、下記の判断基準にて評価する。
試験機 ：スガ試験機株式会社製、磨耗試験機
荷重 ：５００ｇ
移動速度：３０ｍｍ／ｓｅｃ
往復回数：１００回
【００３５】
評価基準：
○：印字部の脱落が無く、地の部分の汚れが無い。
△：印字部の脱落が少しあり、地の部分の汚れがある。
×：印字部の脱落が目立ち、地の部分の汚れが非常にある。
【００３６】
（評価結果）
上記の実施例および比較例の評価結果を、下記の表１に示す。
【表１】

【００３７】
以上説明したように、本発明の熱転写シートは、基材フィルムの一方の面に、少なくとも熱溶融インキ層を設けてあり、該熱溶融インキ層がワックス、樹脂、着色剤から構成され、該樹脂として脂環族系石油樹脂、または脂環族・芳香族系石油樹脂を含有し、該石油樹脂の含有量が熱溶融インキ層の全固形分に対して２０重量％以上４０重量％以下であり、かつ前記ワックスは、針入度が１１以上１３以下のワックスを主成分とし、かつ前記脂環族系石油樹脂、または脂環族・芳香族系石油樹脂の軟化点が１００〜１２５℃の範囲内としている。これにより、上記の石油樹脂を２０重量％以上４０重量％以下の割合で用いて、熱溶融インキ層の溶融粘度が高くなる点を抑制でき、また針入度１１以上１３以下のワックスを使用しても、その軟らかいワックスを該石油樹脂の硬い皮膜が覆って、印字の転写感度と印字物の耐擦過性の双方において優れたものとなる。さらに、熱溶融インキ層のワックスとして、針入度が１１以上１３以下のワックスを主成分に用いて、溶融インキ層の溶融粘度を低めにして、熱転写シート製造上の作業性と、さらにワックスの原料コストの面で有利となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal transfer sheet, and more particularly to a thermal transfer sheet having good print quality and excellent scratch resistance in the printed matter.
[0002]
[Prior art]
Conventionally, using a thermal transfer sheet in which a heat-melt ink layer in which a colorant such as a pigment or dye is dispersed in a binder such as a heat-meltable wax or resin is supported on a base sheet such as a plastic film, a thermal head, etc. There is known a melt transfer system in which energy corresponding to image information is applied by a heating device and a colorant is transferred together with a binder onto an image receiving sheet such as paper or a plastic sheet.
A print image formed by this melt transfer method has high density and excellent sharpness, and is suitable for recording binary images such as characters and line drawings. In addition, by using a thermal transfer sheet having a hot-melt ink layer such as yellow, magenta, cyan, black, etc., by printing and recording each hot-melt ink layer on the image receiving sheet, a multicolor or full-color image can be formed by subtractive color mixing. Formation is also possible.
[0003]
By the way, when printing what has strict standards for line width, line spacing, length like bar code by the melt transfer method, the thermal transfer sheet has good film cutting property of the hot melt ink layer, It is required that sharp printing is possible. In addition, the printed material is required to have a scratch resistance in order to ensure accurate reading by the barcode reader and to prevent the printed portion from being rubbed and soiled by handling the printed material.
On the other hand, the hot-melt ink layer of the thermal transfer sheet is mainly composed of a resin such as an acrylic resin or a vinyl acetate resin, and many types have been proposed.
[0004]
[Problems to be solved by the invention]
However, the conventional thermal transfer sheet uses a wax with a high penetration and a low melting point, such as paraffin wax, in the hot melt ink layer, which facilitates hot melt coating and enhances transfer sensitivity in printing. Is common. This thermal transfer sheet has a problem that the printed material has poor scratch resistance, and reading failure occurs when a printed portion such as a barcode is read.
In addition, when the hot-melt ink layer of the thermal transfer sheet is mainly composed of a wax with a low penetration such as carnauba wax, the scratch resistance of the printed matter is improved, but a wax with a low penetration has a high melting point. There is a drawback that the transfer sensitivity of printing is low. Furthermore, natural products such as carnauba wax have a problem that the production amount is unstable, and therefore the cost is high.
Therefore, the present invention has been made in view of the above circumstances, and even when a wax having a high penetration and a low melting point is used, the print transfer sensitivity is not deteriorated without deterioration of the scratch resistance of the printed matter. It is an object of the present invention to provide a thermal transfer sheet which is excellent in both scratch resistance of printed matter and printed matter, and in terms of workability and cost in production.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a thermal transfer sheet in which at least a hot melt ink layer is provided on one surface of a base film, wherein the hot melt ink layer is composed of a wax, a resin, and a colorant, The resin contains an alicyclic petroleum resin or an alicyclic / aromatic petroleum resin, and the content of the petroleum resin is 20% by weight or more and 40% by weight or less based on the total solid content of the hot-melt ink layer. And the wax has a penetration of 11 to 13 as a main component, and the softening point of the alicyclic petroleum resin or alicyclic / aromatic petroleum resin is 100 to 125 ° C. It is characterized by being within the range. In addition, all the penetrations prescribed | regulated by this invention are data in 25 degreeC.
[0006]
The operation of the present invention is as follows. The thermal transfer sheet of the present invention has at least a hot melt ink layer provided on one surface of a base film, and the hot melt ink layer is composed of a wax, a resin, and a colorant, and the resin is an alicyclic petroleum. A resin, or an alicyclic / aromatic petroleum resin, the content of the petroleum resin is 20% by weight to 40% by weight with respect to the total solid content of the hot-melt ink layer, and the wax is a needle The degree of softening of the alicyclic petroleum resin, or the alicyclic / aromatic petroleum resin is in the range of 100 to 125 ° C., with the wax having a penetration of 11 to 13 as a main component. Thereby, since said petroleum resin has low melt viscosity, even if it uses it in the ratio of 20 weight% or more and 40 weight% or less, the point which the melt viscosity of a hot melt ink layer becomes high can be suppressed, and the penetration degree is 11 or more. Even when a wax of 13 or less is used, since the hard petroleum resin is added to the soft wax, both the transfer sensitivity of printing and the scratch resistance of the printed matter are excellent.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the invention will be described in detail.
The basic form of the thermal transfer sheet of the present invention is a configuration in which at least a hot melt ink layer is provided on one surface of a base film, but a release layer is provided between the hot melt ink layer and the base film. In addition, an adhesive layer can be provided on the hot-melt ink layer, and a heat-resistant layer can be provided on the other surface of the base film.
[0008]
(Base film)
As the substrate film used in the present invention, the same substrate film as that used in a conventional thermal transfer sheet can be used as it is, and other materials can be used, and are not particularly limited.
Specific examples of preferable base film include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer, and the like. Plastic film, condenser paper, paper such as paraffin paper, non-woven fabric, etc., or a base film made by combining these. A particularly preferred base film is a polyethylene terephthalate film. The thickness of the base film can be appropriately changed depending on the material so that the strength and thermal conductivity are appropriate, and the thickness is preferably, for example, 2 to 25 μm.
[0009]
(Peeling layer)
In the thermal transfer sheet of the present invention, a release layer may be provided between the base film and the hot melt ink layer.
The release layer formed on one surface of the base film is melted at the time of thermal transfer to improve the peelability of the hot melt ink layer, and after transfer, at least a part of the image is transferred to the surface of the transfer image together with the hot melt ink layer, The protective layer of the hot-melt ink layer, particularly the transfer image, imparts good slipperiness, and acts to improve the scratch resistance of the transfer image.
In the present invention, first, a release layer is formed on one surface of the substrate film. For example, acrylic resin, silicone resin, fluorine resin, various resins modified with silicone or fluorine can be used for the release layer, and a wax is preferable.
[0010]
As such a wax, various waxes that melt at the time of printing and exhibit releasability are preferable.
Suitable waxes include, for example, microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, whale wax, ibota wax, wool wax, shellac wax, candelilla wax, Various waxes such as petrolactam, partially modified wax, fatty acid ester, fatty acid amide and the like can be mentioned.
Particularly preferred waxes are microcrystalline wax and carnauba wax which have a relatively high melting point and are hardly soluble in a solvent. The release layer is preferably a thin layer, for example, a thickness of about 0.1 to 2 μm in a dry state so as not to reduce the sensitivity of the thermal transfer sheet.
[0011]
(Hot-melt ink layer)
The hot melt ink layer formed on the base film is composed of a wax, a resin, and a colorant, and contains an alicyclic petroleum resin or an alicyclic / aromatic petroleum resin as the resin. The content of the petroleum resin is 20% by weight or more based on the total solid content of the hot-melt ink layer, and the upper limit is about 60% by weight because printing tends to be inferior when the proportion of wax decreases. Yes, more preferably 40% by weight or less, which is easy to apply in a hot melt state.
The alicyclic petroleum resin or the alicyclic / aromatic petroleum resin which is a constituent resin of the hot melt ink layer will be described below.
[0012]
An alicyclic petroleum resin has a structure in which carbon atoms are bonded in a ring and does not belong to an aromatic petroleum resin, and is mainly made from high-purity dicyclopentadiene that is decomposed by distillation of naphtha decomposition products. To do. In addition, a C9 fraction, an ester-containing monomer, a hydroxyl group-containing monomer, etc. may be used for modification.
The method for producing an alicyclic petroleum resin is obtained by thermal polymerization or cationic polymerization of dicyclopentadiene. In the past, it was often produced by cationic polymerization of relatively low purity dicyclopentadiene, but recently, it is often produced by thermal polymerization of high purity dicyclopentadiene.
Examples of the structure of the alicyclic petroleum resin include those represented by the following chemical formula 1 or chemical formula 2.
[0013]
[Chemical 1]

Note that n represents an integer of 1 or more.
[Chemical 2]

[0014]
As the alicyclic petroleum resin, those having a softening point in the range of 80 to 140 ° C. are preferably used, and since the melt viscosity of the petroleum resin is lower than that of other resins, a large amount is contained in the wax ink. Even if it is added to the melt, the melt viscosity can be kept low.
In addition, since the hard petroleum resin is added to the soft wax in the hot melt ink layer, it is excellent in both printing sensitivity and scratch resistance of the printed matter.
Next, the alicyclic / aromatic petroleum resin is a mixture of an alicyclic petroleum resin and an aromatic petroleum resin (which are not molecularly bonded to each other).
Examples thereof include a block copolymer of a polymer block mainly composed of a vinyl aromatic petroleum resin and a polymer block mainly composed of a conjugated diene having an alicyclic structure.
Examples of the vinyl aromatic petroleum resin include styrene, vinyl toluene, and vinyl naphthalene. Examples of the conjugated diene having an alicyclic structure include 1,3-hexadiene.
The above alicyclic / aromatic petroleum resins preferably have a softening point in the range of 80 to 140 ° C., and the melt viscosity of the petroleum resin is lower than that of other resins. Even if it is added in a large amount, the melt viscosity can be kept low.
In addition, since the hard petroleum resin is added to the soft wax, the hot melt ink layer is excellent in both the printing transfer sensitivity and the scratch resistance of the printed matter.
[0015]
In addition to the above petroleum resins, the binder resin may be medium density polyethylene, high density polyethylene, polypropylene resin, polyester resin, polyamide resin, ionomer resin, ethylene-acrylate resin, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer. Thermoplastic resins having a relatively low softening point such as polymers and polystyrene resins can be used.
Examples of the wax used in the hot melt ink layer include, for example, microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, whale wax, ibota wax, wool wax, shellac. Various waxes such as wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, fatty acid amide and the like can be mentioned.
[0016]
Among the above waxes, it is preferable that hot melt coating is easy to perform as a hot melt ink using a wax having a penetration of 4 or more and a low melting point as a main component, and preferably increasing the printing sensitivity. As the wax having a penetration of 4 or more, specifically, paraffin wax, microcrystalline wax or the like can be used as long as the penetration is 4 or more. In general, it is desirable to use a wax having a penetration of 10 or more. Further, the upper limit of the penetration of the wax to be used is about 30, preferably about 20.
The wax content in the hot melt ink layer is about 40 to 70% by weight with respect to the total solid content of the hot melt ink layer.
In the present invention, each colorant such as yellow, magenta, cyan, black, and white can be appropriately selected from conventionally known dyes and pigments.
In the coating liquid for the hot-melt ink layer of the present invention, the binder resin and the colorant and, if necessary, auxiliary agents such as a plasticizer, a surfactant, a lubricant and a fluidity modifier can be added.
[0017]
The hot-melt ink layer is formed by applying a coating solution for forming a hot-melt ink layer blended with the above-mentioned materials into conventionally known coating means such as hot melt coating, hot lacquer coating, gravure direct coating, gravure reverse coating, knife coating, It can be performed by a method such as air coating or roll coating.
In the thermal transfer sheet of the present invention, it is desirable to use a wax having a penetration of 4 or more and a low melting point as a wax for the hot melt ink layer, and the hot melt ink layer is preferably formed by hot melt coating.
The thickness of the hot melt ink layer is preferably about 0.5 to 6 μm in a dry state. If it is less than 0.5 μm, sufficient colorability cannot be obtained, and if it exceeds 6 μm, a large amount of printing energy is required, which is not preferable.
[0018]
(Adhesive layer)
In the thermal transfer sheet of the present invention, an adhesive layer can be provided on the hot melt ink layer. The adhesive layer can improve the adhesion between the image-receiving sheet and the transferred hot-melt ink layer.
This adhesive layer is mainly composed of a thermoplastic resin that softens and exhibits adhesiveness by heating with a thermal head, laser, etc. In order to prevent blocking when the resulting thermal transfer sheet is wound into a roll, waxes are used. Antiblocking agents can be added, such as higher fatty acid amides, esters and salts, fluororesin and inorganic powders.
[0019]
Examples of thermoplastic resins include ethylene-vinyl acetate copolymer (EVA), ethylene-acrylate copolymer (EEA), polyester resin, polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, vinyl chloride resin, vinyl chloride. -Vinyl acetate copolymer, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate, polyvinyl formal, polyvinyl butyral, acetyl cellulose, nitrocellulose, polyvinyl acetate, polyisobutylene, ethyl cellulose or polyacetal, etc. Those having a relatively low softening point, for example, a softening point of 50 to 150 ° C., conventionally used as a heat-sensitive adhesive are preferable.
[0020]
The adhesive layer is formed by hot melt coating or an adhesive layer forming coating solution prepared by dissolving or dispersing the thermoplastic resin and additives in a suitable organic solvent or water, with a conventionally known hot melt coat, hot lacquer coat, A thickness of 0.05 to 5 μm is provided in a dry state by a method such as gravure direct coating, gravure reverse coating, knife coating, air coating or roll coating.
When the thickness of the dried coating film is less than 0.05 μm, the adhesiveness between the image receiving sheet and the hot melt ink layer is poor, and transfer failure occurs during printing. On the other hand, if the thickness exceeds 5 μm, the transfer sensitivity at the time of printing decreases, and satisfactory print quality cannot be obtained.
[0021]
(Heat resistant layer)
In the present invention, when a heat-sensitive material is used as the base film, it is preferable to provide a heat-resistant layer that improves the slidability of the thermal head and prevents sticking on the surface in contact with the thermal head. The heat-resistant layer includes a heat-resistant resin and a thermal release agent or a substance that functions as a lubricant as basic constituent components.
By providing such a heat-resistant layer, thermal printing can be performed without causing sticking even on a heat transfer sheet based on a heat-sensitive plastic film, making the plastic film difficult to cut and easy to process. Etc. can be utilized.
[0022]
This heat-resistant layer is formed by suitably using a binder resin to which a slip agent, a surfactant, inorganic particles, organic particles, a pigment and the like are added.
Examples of binder resins used in the heat-resistant layer include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, and nitrified cotton, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, and polyvinyl acetal. , Polyvinyl pyrrolidone, acrylic resin, polyacrylamide, vinyl resins such as acrylonitrile-styrene copolymer, polyester resin, polyurethane resin, silicone-modified or fluorine-modified urethane resin, and the like.
[0023]
Among these, it is preferable to use a crosslinked resin using several reactive groups, for example, those having a hydroxyl group, and using a polyisocyanate or the like as a crosslinking agent.
As described above, the heat-resistant layer is formed by dissolving or dispersing a material obtained by adding a slipping agent, a surfactant, inorganic particles, organic particles, a pigment, etc. to a binder resin in an appropriate solvent, The coating solution is coated by a conventional coating means such as a gravure coater, roll coater, wire bar, etc., and dried.
[0024]
【Example】
Next, the present invention will be described more specifically with reference to examples and comparative examples. In the text, “part” or “%” is based on weight unless otherwise specified.
(Example 1)
As a base film, a hot melt coating of a hot melt ink layer coating liquid 1 having the following composition is applied to one surface of a 4.5 μm thick polyethylene terephthalate film (Lumirror, manufactured by Toray Industries, Inc.), and the dry coating amount is 3 The heat transfer ink layer is formed by applying and drying to 0.0 g / m ² to form a heat-melt ink layer.
In addition, a heat-resistant layer coating solution having the following composition is applied to the other surface of the base film in advance by gravure coating so that the dry coating amount is 0.3 g / m ² and dried. Form it.
[0025]
Hot melt ink layer coating liquid 1
Carbon black (Mitsubishi Chemical Corporation, # 44) 15 parts paraffin wax (penetration 11) 40 parts carnauba wax 10 parts alicyclic / aromatic petroleum resin 30 parts (Zeon Corporation, Quintone 1925, softening point 125 ℃)
Ethylene-vinyl acetate copolymer 5 parts (MI = 150, VA = 19%)
[0026]
Heat-resistant layer coating solution Styrene acrylonitrile copolymer resin 11 parts linear saturated polyester resin 0.3 part zinc stearyl phosphate 6 parts melamine resin powder 3 parts methyl ethyl ketone 80 parts
(Example 2)
The thermal transfer sheet of Example 2 was prepared in the same manner as in Example 1 except that the hot melt ink layer coating liquid 1 used in Example 1 was changed to the coating liquid 2 having the following composition. Hot melt ink layer coating liquid 2
Carbon black (Mitsubishi Chemical Corporation, # 44) 15 parts paraffin wax (penetration 11) 50 parts carnauba wax 10 parts alicyclic / aromatic petroleum resin 20 parts (Zeon Corporation, Quintone 1925, softening point 125 ℃)
Ethylene-vinyl acetate copolymer 5 parts (MI = 150, VA = 19%)
[0028]
(Example 3)
The thermal transfer sheet of Example 3 was prepared in the same manner as in Example 1 except that the hot melt ink layer coating liquid 1 used in Example 1 was changed to the coating liquid 3 having the following composition. Hot melt ink layer coating liquid 3
Carbon black (Mitsubishi Chemical Corporation, # 44) 15 parts Paraffin wax (Penetration 11) 40 parts Carnauba wax 10 parts Alicyclic petroleum resin 30 parts (Nippon Zeon Corporation, Quintone 1500, softening point 100 ° C.)
Ethylene-vinyl acetate copolymer 5 parts (MI = 150, VA = 19%)
[0029]
Example 4
The thermal transfer sheet of Example 4 was prepared in the same manner as in Example 1 except that the hot melt ink layer coating liquid 1 used in Example 1 was changed to the coating liquid 4 having the following composition. Hot melt ink layer coating solution 4
Carbon black (Mitsubishi Chemical Corporation, # 44) 15 parts paraffin wax (penetration 13) 40 parts carnauba wax 10 parts alicyclic / aromatic petroleum resin 30 parts (Zeon Corporation, Quintone 1925, softening point 125 ℃)
Ethylene-vinyl acetate copolymer 5 parts (MI = 150, VA = 19%)
[0030]
(Comparative Example 1)
A thermal transfer sheet of Comparative Example 1 was prepared in the same manner as in Example 1 except that the hot melt ink layer coating liquid 1 used in Example 1 was changed to a coating liquid 5 having the following composition. Hot melt ink layer coating solution 5
Carbon black (Mitsubishi Chemical Corporation, # 44) 15 parts Paraffin wax (Penetration 11) 60 parts Carnauba wax 10 parts Alicyclic / aromatic petroleum resin 10 parts (Zeon Corporation, Quintone 1925, softening point 125 ℃)
Ethylene-vinyl acetate copolymer 5 parts (MI = 150, VA = 19%)
[0031]
(Comparative Example 2)
A thermal transfer sheet of Comparative Example 2 was prepared in the same manner as in Example 1 except that the hot melt ink layer coating liquid 1 used in Example 1 was changed to a coating liquid 6 having the following composition. Hot melt ink layer coating liquid 6
Carbon black (Mitsubishi Chemical Corporation, # 44) 15 parts Paraffin wax (Penetration 11) 40 parts Carnauba wax 10 parts Modified terpene resin 30 parts (Yasuhara Chemical Co., Ltd., T0115, softening point 115 ° C.)
Ethylene-vinyl acetate copolymer 5 parts (MI = 150, VA = 19%)
[0032]
(Comparative Example 3)
A thermal transfer sheet of Comparative Example 3 was prepared in the same manner as in Example 1 except that the hot melt ink layer coating liquid 1 used in Example 1 was changed to the coating liquid 7 having the following composition. Hot melt ink layer coating solution 7
Carbon black (Mitsubishi Chemical Corporation, # 44) 15 parts paraffin wax (penetration 11) 40 parts carnauba wax 40 parts ethylene-vinyl acetate copolymer 5 parts (MI = 150, VA = 19%)
[0033]
Using the thermal transfer sheets of Examples and Comparative Examples, printing is performed under the following printing conditions, and the printed matter is evaluated for printing quality and scratch resistance by the following evaluation method.
Printing conditions The BC8MK3 printer manufactured by Autoncs was used as the printer to be used, and a barcode pattern was printed on mirror-coated paper at a printing speed of 40 mm / sec.
Evaluation method of print quality The above-mentioned printed matter is visually observed for the bar code transfer state and evaluated according to the following criteria.
○: The transfer state is good.
X: The transfer state is poor.
[0034]
Method for evaluating scratch resistance The above printed matter is subjected to a scratch test by the following method, and the surface state of the printed matter is visually observed and evaluated according to the following criteria.
Tester: Suga Test Instruments Co., Ltd., wear tester load: 500g
Movement speed: 30mm / sec
Number of round trips: 100 times [0035]
Evaluation criteria:
○: There is no dropout of the printed part, and there is no stain on the ground part.
Δ: There is a slight dropout of the printed part, and the ground part is dirty.
X: Dropping of the printed part is conspicuous and the ground part is very dirty.
[0036]
(Evaluation results)
The evaluation results of the above examples and comparative examples are shown in Table 1 below.
[Table 1]

[0037]
As described above, the thermal transfer sheet of the present invention has at least a hot melt ink layer provided on one surface of a base film, and the hot melt ink layer is composed of a wax, a resin, and a colorant. As an alicyclic petroleum resin, or an alicyclic / aromatic petroleum resin, the content of the petroleum resin is 20% by weight or more and 40% by weight or less based on the total solid content of the hot-melt ink layer. The wax has a penetration of 11 to 13 as a main component, and the softening point of the alicyclic petroleum resin or alicyclic / aromatic petroleum resin is in the range of 100 to 125 ° C. It is within. As a result, the above-mentioned petroleum resin can be used in a proportion of 20% by weight or more and 40% by weight or less to suppress the increase in the melt viscosity of the hot-melt ink layer, and a wax having a penetration of 11 to 13 can be used. However, the soft wax is covered with a hard film of the petroleum resin, and both the transfer sensitivity of the print and the scratch resistance of the printed matter are excellent. Further, as the wax of the hot melt ink layer, a wax having a penetration of 11 or more and 13 or less is used as a main component, the melt viscosity of the melt ink layer is lowered, and the workability in manufacturing the thermal transfer sheet is further improved. This is advantageous in terms of raw material costs.

Claims (1)

In a thermal transfer sheet in which at least a hot melt ink layer is provided on one surface of a base film, the hot melt ink layer is composed of a wax, a resin, and a colorant, and the resin is an alicyclic petroleum resin or an alicyclic ring. An aromatic petroleum resin, the content of the petroleum resin is 20% by weight or more and 40% by weight or less based on the total solid content of the hot-melt ink layer, and the wax has a penetration of 11 A thermal transfer sheet comprising a wax of 13 or less as a main component and a softening point of the alicyclic petroleum resin or the alicyclic / aromatic petroleum resin in a range of 100 to 125 ° C.