JP3936128B2 - Thermal transfer recording medium and image forming method - Google Patents

Description

【０１１４】
画像階調性…○：作製したカラー画像がハイライト部からシャドウ部まで忠実に再現されている。
×：ハイライト部からシャドウ部までの再現性が不十分である。
耐光性 … キセノンフェードメーターによりカラー画像面に８０時間照射を行い、その退色率を測定。
○：退色率５％以内
×：退色率５％以上
定着性 … カラー画像面を爪で通常の力で擦ったときの画像部の尾引き度合い。
○：変化なし
×：画像部周辺に汚れあり
高濃度の濃度バランス…フルベタ画像濃度（３色重ね墨濃度）のシアン、マゼンタ、イエローの各色成分の光学濃度の差
○：１０％以内
×：１０％以上
上記表１に示した通り、本発明による感熱記録媒体（実施例１）は、階調再現性において作製したカラー画像がハイライト部からシャドウ部まで忠実に再現され高濃度で色バランスのとれ、更に、記録後の画像の耐久性を有する優れた熱転写記録媒体を得ることができ、本発明の目的が達成されたことがわかる。
【０１１７】
実施例２
実施例１において、カラー画像をシアン、マゼンタ、イエローの３色より作成し、文字及びバーコードの２値化画像をブラックで作成した。
【０１１８】
得られた画像は、実施例１の性能に加え文字及びバーコード部分にも耐性の優れた性能を有することが確認された。
【０１１９】
実施例３
実施例１で得られた熱転写記録媒体を用い、以下に示す受像シート上に画像形成を行った。
【０１２０】
（受像シート構成）
２５μｍのポリエステルフィルム上に以下の各処方新規を順次塗布、乾燥して剥離層、受像層が順次積層された受像シートを得た。
【０１２１】
（剥離層用インキ）
アクリル樹脂 …２０部
メチルエチルケトン …４０部
トルエン …４０部
（受像層用インキ）
エポキシ樹脂（油化シェルエポキシ製：エピコート１００７） …３０部
※エポキシ当量１７５０〜２２００ 軟化点１２８℃ 分子量２９００
メチルエチルケトン …７０部
画像形成された受像シートを最終製品用シートと重ね合わせ受像シート裏面よりヒートローラーにて熱転写を行い、ポリエステルフィルムのみを剥がしたところ、表面に保護層が設けられた良好に転写体を得ることができた。
【０１２２】
実施例４
実施例１で得られた熱転写記録媒体を用い、以下に示す受像シート上に画像形成を行った。
【０１２３】
（受像シート構成）
２５μｍのポリエステルフィルム上に以下の剥離層用インキ、ホログラム形成層用インキを順次塗布、乾燥して剥離層、ホログラム形成層を得た後、熱エンボスによりホログラム形成層の表面に凹凸形状によるホログラム形成を行った。
【０１２４】
（剥離層用インキ）
アクリル樹脂 …２０部
メチルエチルケトン …４０部
トルエン …４０部
（ホログラム形成層用インキ）
塩化ビニル−酢酸ビニル共重合体 …２０部
ウレタン樹脂 …１５部
メチルエチルケトン …７０部
トルエン …３０部
更に、透明薄膜層としてＺｎＳを蒸着によりホログラム形成層表面に設けたのち、以下の受像層用インキを塗布、乾燥して受像層を積層し、受像シートを得た。
【０１２５】
（受像層用インキ）
エポキシ樹脂（油化シェルエポキシ製：エピコート１００７） …２０部
※エポキシ当量１７５０〜２２００ 軟化点１２８℃ 分子量２９００
ウレタン樹脂 …１０部
メチルエチルケトン …７０部
画像形成された受像シートを表面に紫外線発光蛍光剤が印刷された最終製品用シートと重ね合わせ、受像シート裏面よりヒートローラーにて熱転写を行い、ポリエステルフィルムのみを剥がしたところ、表面に保護層が設けられた良好な転写体を得ることができた。
【０１２６】
得られた転写体はセキュリティ機能としてホログラム画像を有しており、セキュリティ性の高いものであった。
【０１２７】
なお、実施例２〜４の結果も上記表１中に示す。
【０１２８】
以上のように、第１の発明に係る熱転写記録媒体によると、面積階調による階調再現性の優れた画像を形成することが可能であり、そして特に、感熱転写の際の熱転写記録層の箔切れ性が良く、且つ光学濃度が高く、しかも、保存性、特に耐光性や機械的強度が優れた転写画像を得ることが可能である。
【０１２９】
実施例５
まず、下記組成の熱転写記録層用インキ組成物を調製した。
【０１３０】
（シアンインキ）
フタロシアニンブルー … ９部
エポキシ樹脂（油化シェルエポキシ製：エピコート１００７） …２０部
※軟化点１２８℃、エポキシ当量１７５０〜２２００、分子量２９００
無色微粒子（シリカ：日本アエロジル製アエロジルＲ９７２） … ４部
メチルエチルケトン …６７部
（マゼンタインキ）
Ｐｉｇｍｅｎｔ Ｒｅｄ ２５４ … ９部
エポキシ樹脂（油化シェルエポキシ製：エピコート１００７） …２０部
※軟化点１２８℃、エポキシ当量１７５０〜２２００、分子量２９００
無色微粒子（シリカ：日本アエロジル製アエロジルＲ９７２） … ４部
メチルエチルケトン …６７部
（イエローインキ）
ジスアゾイエロー … ９部
エポキシ樹脂（油化シェルエポキシ製：エピコート１００７） …２０部
※軟化点１２８℃、エポキシ当量１７５０〜２２００、分子量２９００
無色微粒子（シリカ：日本アエロジル製アエロジルＲ９７２） … ４部
メチルエチルケトン …６７部
上記処方の熱転写記録層用インキを、裏面に耐熱処理を施した厚さ５．４μｍのポリエチレンテレフタレートフィルムに、シアンとマゼンタについては乾燥膜厚が０．５μｍになるように、また、イエローについては乾燥膜厚が０．８μｍになるように塗布及び乾燥して本発明の熱転写記録媒体を得た。
【０１３１】
次に、１００μｍの易接着ポリエステルフィルムの易接着面に下記の受像層インキを用いて、乾燥膜厚が５μｍになるように塗布及び乾燥して、受像シートを得た。
【０１３２】
（受像層インキ）
エポキシ樹脂（油化シェルエポキシ製：エピコート１００７） …３０部
※軟化点１２８℃、エポキシ当量１７５０〜２２００、分子量２９００
メチルエチルケトン …７０部
こうして得られたシアンの熱転写記録媒体の熱転写記録層面と受像シートとを重ね、サーマルヘッドを用いて、サーマルヘッドの発熱部に応じた面積階調によるシアン画像を得た。次にマゼンタの熱転写記録媒体を用いて、シアン画像が形成されている受像シート上にシアンと同様にして面積階調によるマゼンタ画像を形成した。同様にしてイエロー画像を形成し、受像シート上に面積階調のみからなるカラー画像を形成させることができた。
【０１３３】
比較例４
実施例と同じ処方の熱転写記録層用インキを、裏面に耐熱処理を施した厚さ５．４μｍのポリエチレンテレフタレートフィルムに、シアンとマゼンタとイエローすべての乾燥膜厚が０．８μｍになるように塗布及び乾燥して、熱転写記録媒体を得た。
【０１３４】
こうして得られたシアンの熱転写記録媒体の熱転写記録層面と実施例１と同じ受像シートとを重ね、サーマルヘッドを用いて、サーマルヘッドの発熱部に応じた面積階調によるシアン画像を得た。
【０１３５】
次に、マゼンタの熱転写記録媒体を用いて、シアン画像が形成されている受像シート上にシアンと同様にして面積階調によるマゼンタ画像を形成した。同様にしてイエロー画像を形成し、受像シート上に面積階調のみからなるカラー画像を形成させることができた。
【０１３６】
実施例５及び比較例４で得られた画像は、ともに各色の反射濃度が１．３〜１．５の範囲で良好であった。次に、画像階調性の比較評価を行ったところ、実施例５においては、マゼンタのドットもイエローのドットもハイライト部からシャドウ部まで忠実に再現しているが、比較例４においては、マゼンタのドットおよびイエローのドット形状ともに不安定で、全体的に、色ムラの目立つ画像となった。
【０１３７】
以上のように、第２の発明に係る熱転写記録媒体によれば、面積階調による階調再現性が優れ、しかも保存性、特に耐光性や機械的強度に優れた画像を得ることが可能である。
【０１３８】
【発明の効果】
以上、詳細に説明したように、第１の発明に係る熱転写記録媒体によると、面積階調による階調再現性の優れた画像を形成することが可能であり、そして特に、感熱転写の際の熱転写記録層の箔切れ性が良く、且つ光学濃度が高く、しかも、保存性、特に耐光性や機械的強度が優れた転写画像を得ることが可能である。
【０１３９】
また、第２の発明に係る熱転写記録媒体によれば、面積階調による階調再現性が優れ、しかも保存性、特に耐光性や機械的強度に優れた画像を得ることが可能である。
【図面の簡単な説明】
【図１】従来の熱転写記録媒体の問題点を説明するための図。
【図２】本発明の一実施形態に係る熱転写記録媒体を示す断面図。
【図３】本発明の他実施形態に係る熱転写記録媒体を示す断面図。
【符号の説明】
１，１１…支持体
２ａ，２ｂ，３，３ａ，３ｂ…ドット
１２…熱転写記録層
１３…バックコート層[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a thermal transfer recording medium and image formation using the sameDepends on the methodIn particular, using a thermal transfer recording medium (thermal transfer ribbon) having a thermal transfer recording layer containing a color pigment and a thermal head printer, the thermal transfer recording layer is thermally transferred onto an image receiving sheet in an image-like manner based on image data. The present invention relates to a method of forming an area gradation image.
[0002]
  More specifically, the present invention relates to a thermal transfer recording medium suitable for forming a gradation color image by area gradation by overlapping dots of at least two or more multicolor thermal transfer recording layers, and an image using the same. FormationAbout the method.
[0003]
[Prior art]
Conventionally, a sublimation transfer method and a melt transfer method are known as thermal transfer recording methods for forming a gradation image using a thermal head printer.
[0004]
In the sublimation transfer method, a thermal transfer recording medium provided with a thermal transfer recording layer comprising a sublimation dye (heat transferable dye) and a binder resin on a support is overlapped with an image receiving sheet, and in the thermal transfer recording layer according to the amount of heat of the thermal head. A gradation image is formed by transferring the sublimable dye on the image receiving sheet.
[0005]
However, when an image is formed using such a sublimation dye (heat transferable dye), the formed image is inferior in durability, and use in fields requiring heat resistance and light resistance is limited. In addition, since the thermal recording sensitivity is lower than that of the melt transfer system, it is not suitable as a high-speed recording material that uses a high-resolution thermal head that is expected to be used in the future. have.
[0006]
On the other hand, in the melt transfer method, image information is transferred to a heating device such as a thermal head using a transfer sheet provided with a heat-meltable ink transfer layer consisting of a colorant such as pigment or dye and a binder such as wax on a support. In this method, an image is formed by applying energy according to the above and fusing the ink transfer layer on the image receiving sheet. An image formed by the 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 composed of yellow, magenta, cyan, and black, an image is formed on the image receiving sheet, so that a color image can be obtained regardless of the low image quality derived from the low gradation expression suitability. Can also be formed. Japanese Patent Publication No. 63-65029 discloses such a thermal transfer sheet for color image formation.
[0007]
However, in the case of the thermal transfer sheet described in the above Japanese Patent Publication No. 63-65029, a low melting point crystalline wax is used as a binder for the ink layer. Further, the fixing strength of the transferred image is weak, and if the image portion is rubbed strongly by hand, the image portion is removed.
[0008]
Various proposals have been made as methods for solving such development. For example, JP-A-61-244592 proposes a heat-sensitive transfer sheet having a heat-sensitive ink layer comprising 65% or more of an amorphous polymer, a releasable substance and a colorant.
[0009]
However, the thermal transfer sheet described in JP-A-61-244592 also contains a crystalline wax, so that the fixing strength of the portion where each color is overprinted is insufficient.
[0010]
[Problems to be solved by the invention]
The object of the present invention is to improve the resolution, improve the gradation expression suitability by area gradation, improve the durability of the transferred image, improve the foil cutting property of the transfer recording layer, and improve the optical density of the transferred image An object of the present invention is to provide a thermal transfer recording medium suitable for area gradation.
[0011]
Another object of the present invention is to provide an image forming method using the thermal transfer recording medium.
[0013]
[Means for Solving the Problems]
According to a first aspect of the present invention, a support and a thermal transfer recording layer of a plurality of colors repeatedly provided for each color along the longitudinal direction of the support on the support are provided, and the thermal transfer recording layer is colored A thermal transfer recording of the above-mentioned plurality of colors, including a pigment, an amorphous organic polymer composed of an epoxy resin having a softening point of 70 to 150 ° C., an epoxy equivalent of 600 to 5000, and a molecular weight of 800 to 5000, and fine particles layerIs a thermal transfer recording layer of at least three colors of cyan, magenta, and yellow, and the yellow thermal transfer recording layer is thicker than the cyan thermal transfer recording layer and the magenta thermal transfer recording layer.A thermal transfer recording medium is provided.
[0014]
According to a first aspect of the present invention, there is provided a method for forming an image by a thermal head printer using the above-described thermal transfer recording medium, wherein the thermal transfer recording layer of the thermal transfer recording medium is thermally transferred onto an image receptor on the basis of image data. A step of forming an image by area gradation, and a layer containing an amorphous organic polymer of the same type as the amorphous organic polymer contained in the thermal transfer recording layer is provided on the image receiving surface of the image receiving body. An image forming method is provided.
[0017]
According to a second aspect of the present invention, a support and a thermal transfer recording layer of a plurality of colors repeatedly provided for each color along the longitudinal direction of the support on the support are provided, and the thermal transfer recording layer is colored A plurality of pigments, an amorphous organic polymer composed of an epoxy resin having a softening point of 70 to 150 ° C., an epoxy equivalent of 600 to 5000, and a molecular weight of 800 to 5000, and fine particles, and sequentially transferred Color thermal transfer recording layerIs a thermal transfer recording layer of at least three colors of cyan, magenta, and yellow.There is provided a thermal transfer recording medium characterized in that the average layer thickness of each color of the thermal transfer recording layer other than the thermal transfer recording layer of the color to be transferred is 0.6 μm or less.
[0018]
According to a second aspect of the present invention, there is provided a method of forming an image by a thermal head printer using the above-described thermal transfer recording medium, wherein the thermal transfer recording layer of the thermal transfer recording medium is thermally transferred onto an image receptor on the basis of image data. A step of forming an image by area gradation, and a layer containing an amorphous organic polymer of the same type as the amorphous organic polymer contained in the thermal transfer recording layer is provided on the image receiving surface of the image receiving body. An image forming method is provided.
[0022]
Hereinafter, the thermal transfer recording medium of the present invention will be described in more detail.
[0023]
The thermal transfer recording medium of the present invention comprises a support and a thermal transfer recording layer of a plurality of colors repeatedly provided for each color on the support along at least the longitudinal direction of the support. And a color pigment, an amorphous organic polymer, and fine particles, and the thickness of the thermal transfer recording layer is controlled.
[0024]
The transfer principle of the thermal transfer recording medium of the present invention is as follows. That is, heat is applied to the thermal transfer recording material by a thermal medium such as a thermal head, and the amorphous organic polymer in the thermal transfer recording layer is either melted, semi-molten, or softened by the heat, and the support The adhesiveness is developed as it leaves, and the image is recorded by thermally adhering onto the image receiving sheet. Therefore, when printing is performed by overlapping dots of at least two colors, a clear print free from ink blur is obtained. Moreover, what has the characteristic excellent in mechanical strength as a transferred recorded image is obtained.
[0025]
The transfer mode in which the amorphous organic polymer is semi-melted or softened as described above by heat and the transfer of the thermal transfer recording layer occurs is not only the thermal transfer recording layer but also the thickness of the thermal transfer recording layer. This is largely due to the thinness, and is considered to be closer to the thermal bonding thin film peeling method rather than the melt transfer method (Japanese Patent Laid-Open No. 7-117359). The transfer form of the traditional melt transfer system is considered that the thermal transfer recording layer is simply melted to cause transfer.
[0026]
In addition, the thermal transfer recording layer can be configured by repeatedly coating at least three colors of cyan, magenta, and yellow in the surface order along the longitudinal direction of the support, and the thermal transfer recording layer of each color is sequentially transferred. By doing so, a multicolor image can be formed with high work efficiency.
[0027]
  Thermal transfer recording medium of the present invention and image formation using the sameIn the wayThere are the following two modes.
[0028]
The thermal transfer recording medium according to the first invention is a thermal transfer recording layer of a plurality of colors provided repeatedly for each color along the longitudinal direction of the support.Is a thermal transfer recording layer of at least three colors of cyan, magenta, and yellow, and the yellow thermal transfer recording layer is thicker than the cyan thermal transfer recording layer and the magenta thermal transfer recording layer.It is characterized by that.
[0029]
In this way, by making the thermal transfer recording layer of a specific color of the three colors thicker than the other thermal transfer recording layers, it is possible to obtain a multicolor image having a balanced hue with a high density. .
[0030]
That is, since the dot shape and gradation reproducibility are usually greatly affected by the thickness and differ, the thickness of each color (for example, three colors of yellow, magenta, and cyan) is generally the same. However, the optical density of each color component is often different, and there are cases where a sufficient density cannot be obtained for a specific color, for example, yellow.
[0031]
Therefore, in the first invention, if the thickness of the thermal transfer recording layer is within a predetermined range, even if it is changed for each color, there is little influence on the dot shape and gradation reproducibility, so that a sufficient density can be obtained. The thermal transfer recording layer of a specific color which is not present is made thicker than other thermal transfer recording layers. That is, the thickness of the thermal transfer recording layer is different depending on the color.
[0032]
For example, the layer thickness of the yellow color thermal transfer recording layer may be in the range of 0.61 to 1.0 μm, and the layer thickness of the cyan color thermal transfer recording layer and the magenta color thermal transfer recording layer may be in the range of 0.2 to 0.6 μm. Can
In this way, a sufficient optical density can be obtained for any color. As a result, it is possible to form a high-density image in which each color is balanced without impairing the dot shape and gradation expression.
[0033]
  According to a first aspect of the present invention, there is provided image formation in which the above-described thermal transfer recording medium is used, and an image is formed by area gradation based on image data by a thermal head printerProvide wayTo do. The thickness of the thermal transfer recording layer in the thermal transfer recording medium hardly changes even by thermal transfer. This trend is due to thermal transfer recordinglayerHowever, this is remarkable when there are very few low melting point materials (for example, waxes) and many oils and fats are used instead. Therefore, even in an image forming body obtained using the above-described thermal transfer recording medium, the layer thickness of the dots of one color transfer image is larger than the layer thickness of the dots of the other color transfer image.
[0034]
  The image forming method according to the first aspect of the present invention is the above-described thermal transfer recording medium in which a plurality of thermal transfer recording layers of different colors are formed on a support in different colors.Apply to.
[0035]
In this case, the plurality of colors are, for example, at least three colors of yellow, magenta, and cyan. In particular, the thickness of the thermal transfer recording layer of the yellow thermal transfer recording medium is thicker than that of the other colors.
[0036]
The second invention is a thermal transfer recording layer of a plurality of colors.Is a thermal transfer recording layer of at least three colors of cyan, magenta, and yellow.The average layer thickness of the thermal transfer recording layer of the color other than the thermal transfer recording layer of the color to be transferred last is 0.6 μm or less.
[0037]
When a plurality of (for example, yellow, magenta, cyan, etc.) thermal transfer recording layers are selectively heated with a thermal head (usually from the support side) to form an image consisting of dots with area gradations, First, the first color thermal transfer recording layer is heated to form dots, and then the second color thermal transfer recording layer is heated to form dots. This is repeated for the number of colors used for the third and fourth colors, but when forming dots for the second and subsequent colors, the total physical height (thickness) of the dots formed so far is The present inventors have found that the influence on the dot shape is very large.
[0038]
This tendency is characteristic of a thermal transfer recording medium mainly composed of an amorphous organic polymer as in the present invention as compared with a conventional thermal transfer recording medium mainly composed of crystalline wax. The reason is that the thickness formed as the thermal transfer recording layer collapses due to heat (therefore, the image bleeds), whereas the latter has the thickness formed as the thermal transfer recording layer with good reproducibility. This is considered to be due to the fact that it appears in the layer thickness and as a result is also reflected in the good dot shape (therefore, the image does not blur).
[0039]
In view of this, the present invention provides a method for preventing the image from blurring and achieving a beautiful dot shape for the second and subsequent colors by increasing or decreasing the thickness of the thermal transfer recording layer formed as a medium. To do.
[0040]
As a form in which dots are transferred onto the support 1, FIG.(A)As shown in FIG. 1, when the other color dot 2b exists in the vicinity of the first color dot 2a on the support 1, and the second color dot 3 is formed between them, or FIG.(B)As shown in FIG. 2, when the second color dot 3a is formed on the first color dot 2a, or the second color dot 3b is formed on the first color dot 2b in a shifted position. There is.
[0041]
FIG.(B)In the case of the transfer shape as shown in FIG. 2, it was expected that the formation of the second color dots 3a and 3b would be an obstacle if the height of the first color dots 2a and 2b was high (thickness). As a result, the inventors have verified through experiments, and found that the dot shape of the second and subsequent colors changes drastically when the thickness of the thermal transfer recording layer of the first color is 0.6 μm.
[0042]
That is, if the thickness of the thermal transfer recording layer for the first color exceeds 0.6 μm, the dot shape becomes unstable and color unevenness occurs in the thermal transfer of the thermal transfer recording layer for the second color or more. It was found that by adjusting the thickness of the film to 0.6 μm or less, the dot shape is stabilized, and an image having excellent gradation reproducibility without color unevenness can be obtained.
[0043]
In order to obtain a beautiful image, it is preferable to consider the density as well as the uniformity of the dot shape. The optical reflection density is preferably at least 1.1 or more on the white support, and it has also been found that the uniformity of the dot shape can be easily connected directly by the beauty of the image.
[0044]
Further, when the average particle diameter of the colored pigment is 0.5 μm or less and the ratio of the pigment having a particle diameter exceeding 1 μm in the particle diameter distribution is 10% or less, the average layer of the above-mentioned thermal transfer recording layer It was also found that the effect of controlling the thickness can be maximized. The presence of a large aggregate of colored pigments is not preferable because it disturbs the outline of the dot shape.
[0045]
The average diameter of the pigment can be measured by using an autosizer based on a light scattering system (AUTOSIZER: commercially available from MARVERRUN), a Coulter counter method, processing of an SEM observation image, or the like.
[0046]
The order of printing is not particularly specified, but it is necessary to maintain a thickness of 0.6 μm or less for colors other than the last printed color. That is, if printing is performed in the order of yellow, magenta, and cyan, the thickness of each of the yellow and magenta ink layers (thermal transfer recording layers) must be 0.6 μm or less. Not as long. The thermal transfer recording layers of colors other than the color to be printed last only have to have a thickness of 0.6 μm or less.
[0047]
  According to a second aspect of the present invention, there is provided image formation in which the above-described thermal transfer recording medium is used and an image is formed by area gradation based on image data by a thermal head printer.Provide wayTo do. Since the thickness of the thermal transfer recording layer in the thermal transfer recording medium hardly changes even by thermal transfer, even in the image formed body obtained by using the thermal transfer recording medium described above, among the transferred images in which a plurality of color dots are superimposed. The average layer thickness of dots of colors other than the transferred image of the uppermost dot color is 0.6 μm or less.
[0048]
  The image forming method according to the second invention is the above-described thermal transfer recording medium in which a plurality of thermal transfer recording layers of different colors are formed on a support in different colors.Apply to.
[0049]
In this case, the plurality of colors are, for example, at least three colors of yellow, magenta, and cyan.
[0050]
As will be described later, when it is difficult to directly transfer the image to an image carrier to which image formation is finally desired with a thermal head printer, the image was once transferred onto an intermediate image receiving sheet (intermediate image carrier). Thereafter, the obtained transfer image can be retransferred onto the final image carrier. In such a case, the order of the overlapping of dots of each color of the transfer image formed on the final image formation body This is the opposite of the case where it is formed by thermal transfer directly performed by a thermal head printer. Therefore, among the transferred images in which dots of a plurality of colors are stacked, the dots of the transferred image of colors other than the transferred image on the image carrier side The average layer thickness is 0.6 μm or less.
[0051]
There are roughly two types of methods for transferring an image onto an image carrier that is a support for the final image forming body after an image is once recorded on an intermediate image receiving sheet (intermediate image carrier). There is a way.
[0052]
That is, (1) an image (formed by a collection of dots) formed on an intermediate image receiving sheet and an image receiving layer including an image recording surface on which the image is formed are put together on an image carrier. In this transfer method, the intermediate image receiving sheet may be designed to have an image receiving layer so that it can be peeled off from the support and transferred. This is convenient because the image receiving layer transferred onto the image carrier also serves as a protective layer for protecting the image.
[0053]
Another method is (2) a method of transferring only an image (formed by a collection of dots) formed on an intermediate image receiving sheet onto an image carrier, and unlike the former, The image receiving layer including the image recording surface on which the image is formed is not transferred together with the image. According to this method, if it is desired to provide a protective layer on the image carrier to protect the image provided on the image carrier, a protective layer must be formed by adding another process such as transfer or coating. I must.
[0054]
In both cases (1) and (2), when transferring onto an image carrier, transfer by heating and pressing is generally most convenient, but it should not necessarily be limited to heating and pressing. Absent. In addition, when transferring onto the image carrier, an adhesive or an adhesive sheet is interposed between the transfer surface of the image carrier and the transfer image surface on the intermediate image receiving sheet side to be transferred. It is also preferable to use a technique such as
[0055]
Also, in both cases (1) and (2), a plurality of colors of the transfer image formed on the intermediate image receiving sheet are transferred together to the image carrier, or one color on the intermediate image receiving sheet. Whether the transfer image is transferred each time the transfer image is formed may be appropriately selected by designing the process and the intermediate image receiving sheet.
[0056]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the thermal transfer recording medium of the present invention will be described more specifically.
[0057]
FIG. 2 shows a thermal transfer recording medium according to the present invention in which a thermal transfer layer 12 is provided on a support 11.
[0058]
As the support 11 that can be used in the present invention, those conventionally used for sublimation transfer type and melt transfer type can be used. Specific examples include plastic films such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, polycarbonate, polyvinyl chloride, polystyrene, polyimide, nylon, and polyvinylidene chloride, and papers such as condenser paper and paraffin paper. However, a polyester film is particularly preferable.
[0059]
The thickness of the support 11 is 2 to 50 μm, more preferably 2 to 16 μm.
[0060]
The thermal transfer recording layer 12 contains a color pigment, an amorphous organic polymer, and fine particles.
[0061]
Examples of the amorphous organic polymer contained in the thermal transfer recording layer 12 include a vinyl monomer such as butyral resin, polyamide resin, polyester resin, epoxy resin, acrylic resin, vinyl chloride, vinyl acetate, or other single monomer. A copolymer with a monomer can be used.
[0062]
Depending on the performance required for the finally obtained printed matter, various WAXs and low molecular fluids may be added as appropriate. In particular, when heat resistance and scratch resistance are required, It is preferable to use only an amorphous organic polymer. Even in this case, a beautiful image can be obtained according to the present invention.
[0063]
As the amorphous organic polymer, an epoxy resin can be used. As the epoxy resin, the softening point is from 70 ° C. in consideration of printing suitability to a heat medium such as a thermal head and durability of an image after transfer recording. It is preferable to use the thing of the range of 150 degreeC.
[0064]
The thermal conditions for thermal transfer using a thermal head are usually 180 to 400 ° C. for several milliseconds. Further, in order to perform thermal transfer recording as described above, it is necessary to heat until the epoxy resin is melted, semi-molten, or softened.
[0065]
Accordingly, considering the amount of heat supplied from the thermal head and the molten state of the epoxy resin, the upper limit of the melting point of the epoxy resin is 150 ° C. If an epoxy resin having a melting point exceeding this upper limit is used, more energy is required at the time of transfer, and the life of the thermal head becomes extremely short.
[0066]
The lower limit of the melting point of the epoxy resin is set to 70 ° C. in consideration of the storage stability of the image after transfer recording. When an epoxy resin having a melting point of less than 70 ° C. is used, it is tailed by rubbing by hand. Phenomenon occurs.
[0067]
The epoxy resin used as the main material for the thermal transfer recording layer of the present invention has particularly preferably an epoxy equivalent (gram number of resin containing 1 gram of epoxy group) of 600 to 5,000 and a molecular weight (weight average). The molecular weight (hereinafter the same) is 800 to 5000.
[0068]
If the epoxy equivalent of this epoxy resin is lower than the lower limit (less than 600), the image is not sufficiently durable against rubbing, and tailing tends to occur in the transferred image when rubbed by hand. Therefore, it is not preferable. On the contrary, if this epoxy equivalent is higher than the upper limit (exceeding 5,000), the thermal energy required for thermal transfer is too much, and the life of the thermal head is shortened. In addition, the sensitivity of thermal transfer is low, which is not suitable for applications in which an image is to be thermally transferred and recorded at high speed.
[0069]
In addition, if the molecular weight of the epoxy resin is lower than the lower limit (less than 800), the durability of the image against rubbing is not sufficient, and tailing tends to occur in the transferred image when rubbing by hand. Absent. Conversely, if this molecular weight is higher than the above upper limit (exceeding 5,000), the thermal energy required for thermal transfer will be too great, reducing the life of the thermal head. In addition, since the sensitivity of thermal transfer is low, it is not preferable because it is unsuitable for applications in which an image is to be thermally transferred and recorded at high speed.
[0070]
The most preferred epoxy resin in the present invention is when all the properties of softening point, epoxy equivalent weight, and molecular weight are in the respective ranges at the same time. In this case, a high effect can be obtained particularly with respect to the transferability and durability of the image.
[0071]
For these reasons, an epoxy resin having a melting point of 70 to 150 ° C., an epoxy equivalent of 600 to 5000, and a weight average molecular weight of 800 to 5000 is selected. As such an epoxy resin, bisphenol is used. Glycidyl ether type epoxy resins such as A diglycidyl ether, bisphenol F diglycidyl ether, resorcinol diglycidyl ether, cresol novolac polyglycidyl ether, tetrabromobisphenol A diglycidyl ether, bisphenol hexafluoroacetone glycidyl ether, phthalic acid diglycidyl ester, Glycidyl ester type epoxy resin such as dimer acid diglycidyl ester, triglycidyl isocyanurate, tetraglycidylaminodiphenylmethane, tetraglycidyl Meta alkoxy such as Men diamine glycidyl amine type epoxy resins, and hexa hydro bisphenol A diglycidyl ether, polypropylene glycol diglycidyl ether, and aliphatic epoxy resins such as neopentyl glycol diglycidyl ether. Any of these may be selected.
[0072]
The fine particles contained in the thermal transfer recording layer 12 serve as fillers. The fine particles are preferably colorless or pale. Colorless or light color means that the color is light enough not to substantially affect the color and density of the image transferred by the thermal transfer recording layer.
[0073]
These fine particles are components necessary for improving the transferability during thermal transfer, specifically the dot shape on which the transferred image is formed, and the gradation reproducibility. This is so as not to impair the color development of the colored image formed by thermal transfer. Examples of such colorless or light-colored fine particles include silica, calcium carbonate, kaolin, clay, starch, zinc oxide, Teflon powder, polyethylene powder, polymethyl methacrylate resin beads, polyurethane resin beads, benzoguanamine and melamine resin beads. Can be mentioned. Among the above, silica fine particles are particularly preferable.
[0074]
Various known pigments can be used as the color pigment contained in the thermal transfer recording layer 12. For example, carbon black is preferable for black monochromatic printing, and for multicolor printing, pigments for forming yellow, magenta, and cyan, and four-color pigments obtained by adding black to these three-color pigments are used. These pigments can be used alone or in combination of two or more.
[0075]
For multi-color printing, it is preferable to use an organic pigment when the chromaticity faithful reproducibility is required in addition to the dot shape. In particular, when trying to faithfully reproduce a full color with yellow, magenta, and cyan dots-on-dots, the sharpness of the pigment hue is an important factor, in which case at least 80% by weight in the colored pigment. Is preferably occupied by an organic pigment.
[0076]
Examples of organic pigments include azo pigments such as phthalimide yellow, benzimidazolone orange, sulfoamide yellow, and benzimidazolone yellow, phthalocyanine pigments, diketopyrrolopyrrole, quinophthalone, isoindolinone, diaminodianthraquinone, etc. Can be mentioned.
[0077]
The composition of the composition for forming the thermal transfer recording layer 12 is such that the amount of the color pigment is preferably 20 to 30 parts by weight, more preferably 25 to 30 parts by weight, and the composition of the amorphous organic polymer The amount is preferably 40 to 80 parts by weight, more preferably 50 to 70 parts by weight, and the amount of the fine particles is preferably 1 to 30 parts by weight, more preferably 5 to 15 parts by weight.
[0078]
When the blending amount of the color pigment is less than the above range, it becomes difficult to obtain a desired print density, and when it is large, the film strength tends to decrease. When the amount of the amorphous organic polymer is less than the above range, the film strength tends to decrease. When the amount is large, the transferability, specifically the dot shape on which the transferred image is formed, and the gradation reproducibility. Etc. tend to be worse. When the amount of fine particles is less than the above range, the transferability, in particular, the dot shape on which the transferred image is formed, and the gradation reproducibility tend to deteriorate. Is difficult to obtain.
[0079]
In the thermal transfer recording medium of the present invention, the thermal transfer recording layer can contain other components in addition to the color pigment, the amorphous organic polymer, and the fine particles. Examples of such other components include a dispersant represented by a surfactant and the like. The blending amount is preferably 0.1 to 10 parts by weight when the total amount of the color pigment, amorphous organic polymer and fine particles is 100 parts by weight.
[0080]
If the amount of the other component is too small, the effect of the addition of the other component is not exerted. Conversely, if the amount of the other component is too large, it is difficult to plant the effect of the present invention. There is a case.
[0081]
When the other component is a dispersant, its role aims at the following effects. In other words, the formation of the thermal transfer recording layer on the support is generally performed by adding an appropriate amount of an appropriate volatile solvent to a composition having an appropriate amount to form the thermal transfer recording layer to obtain a coating solution. After an appropriate amount is applied to an appropriate place on the support, the solvent component is volatilized. At this time, in the case where a problem that seems to be caused by undesired aggregation of the colored pigment or fine particles occurs, a dispersing agent is added to the coating liquid to give preferable dispersibility to the colored pigment or fine particles. It is possible to solve the problem that seems to be caused by aggregation.
[0082]
The thermal transfer recording medium of the present invention comprises a composition obtained by dispersing or dissolving a colorant, an epoxy resin and colorless fine particles in a solvent on a support such as coated paper or (preferably) plastic. It can be manufactured by applying by a solvent coating method such as coating, air knife coating, gravure coating, roll coating or the like and drying to form a thermal transfer recording layer.
[0083]
The film thickness of the thermal transfer recording layer 12 is generally several μm or less, preferably 0.2 to 1.0 μm, more preferably 0.4 to 0.8 μm.
[0084]
When the film thickness is less than 0.2 μm, it is difficult to obtain a sufficient concentration, and when it exceeds 1.0 μm. Due to the difference in resolution level, transfer according to the heat generation portion of the thermal head becomes difficult, and in particular, the dot shape on which the transfer image is formed, and the gradation reproducibility tend to be inferior.
[0085]
Although not shown, the thermal transfer recording layer is not limited to YMC (yellow, magenta, cyan) or YMCK (K is black) thermal transfer recording layer capable of recording an image or the like by at least coloring. The thermal transfer recording layer can be provided.
[0086]
This applies to the case where a plurality of colors are separately applied to the thermal transfer recording medium or only one color is provided, and any type other than recording these by coloring (or the purpose) As an example of the thermal transfer recording layer), an adhesive transfer layer that has a thermal transfer property and also serves as an adhesive layer at the transfer destination, or also has a thermal transfer property, and prevents counterfeiting at the transfer destination. It is a special effect layer (transferable hologram layer, transferable diffraction grating layer, etc.) that plays a role in facilitating the discovery of effects and counterfeits.
[0087]
Other types of thermal transfer recording layers do not necessarily have to satisfy the requirements of the thermal transfer recording layer containing the color pigment of the thermal transfer recording medium according to the present invention.
[0088]
Here, in the anti-counterfeit layer, which is an example of another type of thermal transfer recording layer, a material that forms fine particles (or flakes, etc.) to be internally added to the layer is particularly important. For example, a fluorescent agent (phosphorescent agent) that emits fluorescence (or phosphorescence) when irradiated with an electromagnetic wave (UV, IR, visible light, etc.) of a certain wavelength, or absorbs an electromagnetic wave (IR, etc.) of a certain wavelength. Examples thereof include an electromagnetic wave absorber that is easy to be treated, and a magnetic material having magnetism.
[0089]
Further, when heat is applied using a thermal head from the side of the support 11 where the thermal transfer recording layer 12 is not provided, and the thermal transfer recording layer 12 is transferred onto the image receiving sheet, the thermal head adheres to the support 11 and is subjected to thermal transfer. In order to prevent the smooth running of the recording medium from being obstructed, it is desirable to provide a backcoat layer 13 on the side of the support 11 where the thermal transfer recording layer 12 is not provided, as shown in FIG.
[0090]
Examples of the material used for the back coat layer 13 include nitrocellulose, a polyester resin, an acrylic resin, a vinyl resin, or the like containing silicon oil, or a silicon-modified resin. Moreover, you may use a crosslinking agent together in order to improve heat resistance.
[0091]
The coating thickness when the back coat layer 13 is provided is preferably about 0.1 to 4 μm.
[0092]
As the image receiving sheet used for forming an image using the thermal transfer recording medium as described above, paper such as high-quality paper, coated paper, plastic film such as polyester film, polyvinyl chloride film, polypropylene film, or paper And an image receiving layer coated on a plastic film. The image receiving layer used here is preferably an epoxy resin. That is, by using an epoxy resin as the image receiving layer, even if the thermal transfer recording layer of the thermal transfer recording medium is not sufficiently melted at the time of thermal transfer, the thermal transfer recording layer and the image receiving layer are adhered well by heat at the time of thermal transfer, and sufficient Since printing is performed when the foil is cut, the transferability, specifically the dot shape on which the transfer image is formed, the gradation reproducibility, and the like are improved. Furthermore, the formed image has excellent image resistance such as abrasion resistance and scratch resistance.
[0093]
In addition, when it is difficult to directly form an image on a sheet on which image formation is desired, an image may be once formed on the image receiving sheet, and the transferred image may be retransferred onto the final sheet. Such an indirect transfer method not only increases the selectivity of the final sheet, but also provides a protective layer on the image-receiving sheet, so that a protective layer can be provided on the final transfer image to improve image resistance. In addition, by providing a security layer such as a hologram forming layer on the image receiving sheet, it is possible to improve the security of the final transfer image.
[0094]
Conventionally known applying means are used as the means for applying thermal energy used when obtaining the gradation image representation by area gradation using the thermal transfer recording medium of the present invention as described above and the image receiving sheet as described above. It is possible to obtain a gradation image by controlling the thermal energy.
[0095]
  The present inventionObtained by the image forming methodThe image forming body can be suitably applied to various cards such as an ID card and a cash card, a passport, and the like.
[0096]
【Example】
Next, the present invention will be described more specifically with reference to various examples and comparative examples. In the text, “part” or “%” is based on weight unless otherwise specified.
[0097]
Examples 1 to 5 below relate to the first invention, and Example 6 relates to the second invention.
[0098]
Example 1
First, an ink composition for a thermal transfer recording layer having the following composition was prepared.
[0099]
(Cyan ink)
Phthalocyanine blue: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
(Magenta ink)
Carmin 6B ... 9 copies
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
(Yellow ink)
Disazo yellow: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
Using a gravure printing machine, heat transfer recording layer ink of the above formulation, heat-treated on the back, polyethylene terephthalate film with a thickness of 5.4 μm, using a gravure printing machine, dry film thickness is cyan, magenta is 0.6 μm, yellow is 0 The thermal transfer recording medium of the present invention was obtained by repeatedly coating the film in the order of the surface along the lengthwise direction so as to have a thickness of 0.8 μm.
[0100]
Next, using the following image-receiving layer ink on the easy-adhesion surface of the 100-μm-thick easily-adhesive polyester film, it was applied and dried to a dry film thickness of 5 μm to obtain an image-receiving sheet.
[0101]
(Image-receiving layer ink)
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 30 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Methyl ethyl ketone: 70 parts
The obtained image receiving sheet and the thermal transfer recording layer surface of the thermal transfer recording medium are overlaid, and using a thermal head, an image with an area gradation corresponding to the heat generating part of the thermal head is sequentially formed in the order of cyan, magenta, and yellow. A full-color image consisting only of area gradations could be formed on the sheet.
[0102]
Comparative Example 1
The following sublimation transfer type ink compositions were prepared as thermal transfer recording layer inks.
[0103]
(Cyan ink)
C. I. Solvent Blue 63 ... 5 parts
Butyral resin (BX-1 manufactured by Sekisui Chemical Co., Ltd.) 5 parts
Methyl ethyl ketone 60 parts
Toluene: 30 parts
(Magenta ink)
C. I. Disperse Red 60 ... 5 copies
Butyral resin (BX-1 manufactured by Sekisui Chemical Co., Ltd.) 5 parts
Methyl ethyl ketone 60 parts
Toluene: 30 parts
(Yellow ink)
C. I. Disperse Yellow 201 ... 5 parts
Butyral resin (BX-1 manufactured by Sekisui Chemical Co., Ltd.) 5 parts
Methyl ethyl ketone 60 parts
Toluene: 30 parts
Using a gravure printing machine, the thermal transfer recording layer ink of the above formulation is heat-treated on the back surface and a 5.4 μm thick polyethylene terephthalate film, and the dry film thickness is 1.0 μm for all cyan, magenta, and yellow. In this manner, the thermal transfer recording medium of Comparative Example 1 was obtained by repeatedly coating the film in the surface order along the longitudinal direction, coating and drying.
[0104]
Next, the following dye-receiving layer ink was applied and dried on the easy-adhesive surface of a 100-μm easy-adhesive polyester film so that the dry film thickness was 4 μm, and then aged at 45 ° C. for 1 week to obtain an image-receiving sheet. .
[0105]
(Ink for dye receiving layer)
Acetal resin: 10 parts
Vinyl chloride-vinyl acetate copolymer resin: 10 parts
Tricon oil… 2 parts
Isocyanate resin 3 parts
Methyl ethyl ketone 50 parts
Toluene: 25 parts
The dye-receiving layer surface of the obtained image-receiving sheet and the thermal transfer recording layer surface of the thermal transfer recording medium were overlapped, and images were formed in the order of yellow, magenta, and cyan using a thermal head to obtain a color image.
[0106]
Comparative Example 2
In Example 1, a thermal transfer recording medium was produced and a color image was formed in the same manner as in Example 1 except that the dry film thickness of the ink for the thermal transfer recording layer was 0.6 μm for cyan, magenta, and yellow.
[0107]
Comparative Example 3
In Example 1, a thermal transfer recording medium was prepared and a color image was formed in the same manner as in Example 1 except that the dry film thickness of the ink for the thermal transfer recording layer was 1.2 μm for cyan, magenta, and yellow.
[0108]
Reference example 1
In Example 1, a thermal transfer recording medium was produced and a color image was formed in the same manner as in Example 1 except that the thermal transfer recording layer ink was changed to the following formulation.
[0109]
(Cyan ink)
Phthalocyanine blue: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Methyl ethyl ketone: 71 parts
(Magenta ink)
Carmin 6B ... 9 copies
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Methyl ethyl ketone: 71 parts
(Yellow ink)
Disazo yellow: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Methyl ethyl ketone: 71 parts
Phthalocyanine blue… 10 parts
Reference example 2
In Example 1, a thermal transfer recording medium was produced and a color image was formed in the same manner as in Example 1 except that the thermal transfer recording layer ink was changed to the following formulation.
[0110]
(Cyan ink)
Phthalocyanine blue: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1001) ... 20 parts
* Softening point 64 ° C Epoxy equivalent 450-500 Molecular weight 900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
(Magenta ink)
Carmin 6B ... 9 copies
Epoxy resin (Oilized shell epoxy: Epicoat 1001) ... 20 parts
* Softening point 64 ° C Epoxy equivalent 450-500 Molecular weight 900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
(Yellow ink)
Disazo yellow: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1001) ... 20 parts
* Softening point 64 ° C Epoxy equivalent 450-500 Molecular weight 900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
Reference example 3
In Example 1, a thermal transfer recording medium was produced and a color image was formed in the same manner as in Example 1 except that the thermal transfer recording layer ink was changed to the following formulation.
[0111]
(Cyan ink)
Phthalocyanine blue: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1010) ... 20 parts
* Softening point 169 ° C Epoxy equivalent 3000-5000 Molecular weight 5500
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
(Magenta ink)
Carmin 6B ... 9 copies
Epoxy resin (Oilized shell epoxy: Epicoat 1010) ... 20 parts
* Softening point 169 ° C Epoxy equivalent 3000-5000 Molecular weight 5500
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
(Yellow ink)
Disazo yellow: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1010) ... 20 parts
* Softening point 169 ° C Epoxy equivalent 3000-5000 Molecular weight 5500
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
The images obtained in Example 1 and Comparative Examples 1, 2, 3, and Reference Examples 1, 2, and 3 were evaluated for image gradation, light resistance, and security.
[0112]
The results are shown in Table 1 below.
[0113]
[Table 1]

[0114]
Image gradation: ○: The produced color image is faithfully reproduced from the highlight portion to the shadow portion.
X: Reproducibility from the highlight portion to the shadow portion is insufficient.
Light resistance: Irradiates the color image surface with a xenon fade meter for 80 hours and measures the fading rate.
○: Within 5% of fading rate
X: 5% or more of fading rate
Fixability: The degree of tailing of the image area when the color image surface is rubbed with normal force with a nail.
Y: No change
×: Dirt around the image area
High density density balance: Difference in optical density between cyan, magenta, and yellow color components of full solid image density (3-color ink density)
○: Within 10%
×: 10% or more
As shown in Table 1 above, the thermal recording medium according to the present invention (Example 1) is such that the color image produced in gradation reproducibility is faithfully reproduced from the highlight portion to the shadow portion, and the color balance can be achieved at a high density. Furthermore, it can be seen that an excellent thermal transfer recording medium having the durability of an image after recording can be obtained, and the object of the present invention has been achieved.
[0117]
Example2
In Example 1, a color image was created from three colors of cyan, magenta, and yellow, and a binary image of characters and barcodes was created in black.
[0118]
In addition to the performance of Example 1, the obtained image was confirmed to have excellent resistance to characters and barcode portions.
[0119]
Example3
Using the thermal transfer recording medium obtained in Example 1, an image was formed on the following image receiving sheet.
[0120]
(Image receiving sheet configuration)
Each of the following new formulations was sequentially applied onto a 25 μm polyester film and dried to obtain an image receiving sheet in which a release layer and an image receiving layer were sequentially laminated.
[0121]
(Ink for release layer)
Acrylic resin: 20 parts
Methyl ethyl ketone: 40 parts
Toluene: 40 parts
(Image-receiving layer ink)
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 30 parts
* Epoxy equivalent 1750-2200 Softening point 128 ° C Molecular weight 2900
Methyl ethyl ketone: 70 parts
When the image-formed image sheet is overlapped with the final product sheet and thermally transferred from the back surface of the image-receiving sheet with a heat roller and only the polyester film is peeled off, a good transfer body with a protective layer on the surface can be obtained. did it.
[0122]
Example4
Using the thermal transfer recording medium obtained in Example 1, an image was formed on the following image receiving sheet.
[0123]
(Image receiving sheet configuration)
The following release layer ink and hologram formation layer ink are applied onto a 25 μm polyester film in sequence, dried to obtain a release layer and a hologram formation layer, and then a hologram is formed on the surface of the hologram formation layer by means of hot embossing. Went.
[0124]
(Ink for release layer)
Acrylic resin: 20 parts
Methyl ethyl ketone: 40 parts
Toluene: 40 parts
(Hologram forming layer ink)
Vinyl chloride-vinyl acetate copolymer: 20 parts
Urethane resin: 15 parts
Methyl ethyl ketone: 70 parts
Toluene: 30 parts
Furthermore, after depositing ZnS on the surface of the hologram forming layer by vapor deposition as a transparent thin film layer, the following image receiving layer ink was applied and dried to laminate the image receiving layer to obtain an image receiving sheet.
[0125]
(Image-receiving layer ink)
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Epoxy equivalent 1750-2200 Softening point 128 ° C Molecular weight 2900
Urethane resin: 10 parts
Methyl ethyl ketone: 70 parts
The image-formed image-receiving sheet is superposed on the surface of the final product sheet printed with an ultraviolet light-emitting fluorescent agent on the surface, heat-transferred with a heat roller from the back of the image-receiving sheet, and only the polyester film is peeled off. A good transfer body provided was obtained.
[0126]
The obtained transfer body had a hologram image as a security function and had high security.
[0127]
In addition, Example 24The results are also shown in Table 1 above.
[0128]
As described above, according to the thermal transfer recording medium according to the first invention, it is possible to form an image having excellent gradation reproducibility by area gradation, and in particular, the thermal transfer recording layer in the thermal transfer. It is possible to obtain a transfer image having good foil cutting properties, high optical density, and excellent storage stability, particularly light resistance and mechanical strength.
[0129]
Example5
First, an ink composition for a thermal transfer recording layer having the following composition was prepared.
[0130]
(Cyan ink)
Phthalocyanine blue: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C, epoxy equivalent 1750-2200, molecular weight 2900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
(Magenta ink)
Pigment Red 254 9 copies
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C, epoxy equivalent 1750-2200, molecular weight 2900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
(Yellow ink)
Disazo yellow: 9 parts
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 20 parts
* Softening point 128 ° C, epoxy equivalent 1750-2200, molecular weight 2900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil) 4 parts
Methyl ethyl ketone… 67 parts
The heat transfer recording layer ink of the above formulation is heat-treated on the back surface to a 5.4 μm thick polyethylene terephthalate film so that the dry film thickness for cyan and magenta is 0.5 μm, and for yellow The thermal transfer recording medium of the present invention was obtained by applying and drying so that the dry film thickness was 0.8 μm.
[0131]
Next, it applied and dried so that the dry film thickness might be set to 5 micrometers on the easy-adhesion surface of a 100 micrometer easy-adhesion polyester film using the following image receiving layer ink, and obtained the image receiving sheet.
[0132]
(Image-receiving layer ink)
Epoxy resin (Oilized shell epoxy: Epicoat 1007) ... 30 parts
* Softening point 128 ° C, epoxy equivalent 1750-2200, molecular weight 2900
Methyl ethyl ketone: 70 parts
The cyan thermal transfer recording medium thus obtained was overlaid with the thermal transfer recording layer surface and the image receiving sheet, and a cyan image with an area gradation corresponding to the heat generating portion of the thermal head was obtained using a thermal head. Next, using a magenta thermal transfer recording medium, a magenta image with an area gradation was formed on an image receiving sheet on which a cyan image was formed in the same manner as cyan. Similarly, a yellow image was formed, and a color image having only area gradations could be formed on the image receiving sheet.
[0133]
Comparative Example 4
The thermal transfer recording layer ink of the same formulation as the example was applied to a polyethylene terephthalate film with a thickness of 5.4 μm with heat treatment on the back so that the dry film thickness of all cyan, magenta and yellow was 0.8 μm. And dried to obtain a thermal transfer recording medium.
[0134]
The thermal transfer recording layer surface of the cyan thermal transfer recording medium thus obtained and the same image receiving sheet as in Example 1 were overlapped, and a cyan image with an area gradation corresponding to the heat generating portion of the thermal head was obtained using a thermal head.
[0135]
Next, using a magenta thermal transfer recording medium, a magenta image with an area gradation was formed on an image receiving sheet on which a cyan image was formed in the same manner as cyan. Similarly, a yellow image was formed, and a color image having only area gradations could be formed on the image receiving sheet.
[0136]
Example5The images obtained in Comparative Example 4 were all good when the reflection density of each color was in the range of 1.3 to 1.5. Next, when comparative evaluation of image gradation was performed, the example5In this example, both the magenta dots and the yellow dots are faithfully reproduced from the highlight portion to the shadow portion. However, in the comparative example 4, both the magenta dot and the yellow dot shape are unstable. The image was noticeable.
[0137]
As described above, according to the thermal transfer recording medium according to the second invention, it is possible to obtain an image having excellent gradation reproducibility by area gradation and having excellent storage stability, particularly light resistance and mechanical strength. is there.
[0138]
【The invention's effect】
As described above in detail, according to the thermal transfer recording medium according to the first invention, it is possible to form an image having excellent gradation reproducibility by area gradation, and particularly in thermal transfer. It is possible to obtain a transfer image in which the thermal transfer recording layer has good foil cutting properties, high optical density, and excellent storage stability, particularly light resistance and mechanical strength.
[0139]
Further, according to the thermal transfer recording medium of the second invention, it is possible to obtain an image having excellent gradation reproducibility by area gradation and having excellent storage stability, particularly light resistance and mechanical strength.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining problems of a conventional thermal transfer recording medium.
FIG. 2 is a cross-sectional view showing a thermal transfer recording medium according to an embodiment of the present invention.
FIG. 3 is a sectional view showing a thermal transfer recording medium according to another embodiment of the present invention.
[Explanation of symbols]
1,11 ... Support
2a, 2b, 3, 3a, 3b ... dots
12 ... Thermal transfer recording layer
13 ... Back coat layer

Claims (10)

And a thermal transfer recording layer of a plurality of colors repeatedly provided for each color along the longitudinal direction of the support. The thermal transfer recording layer has a color pigment and a softening point of 70 to An amorphous organic polymer composed of an epoxy resin having an epoxy equivalent of 600 to 5000 and a molecular weight of 800 to 5000, and fine particles, and the thermal transfer recording layer of the plurality of colors includes at least cyan and magenta , And yellow three-color thermal transfer recording layer, wherein the thickness of the yellow thermal transfer recording layer is larger than the thickness of the cyan thermal transfer recording layer and the magenta thermal transfer recording layer Medium. 2. The thermal transfer recording medium according to claim 1, wherein the thermal transfer recording layer has a thickness in the range of 0.2 to 1.0 [mu] m. The yellow thermal transfer recording layer has a thickness of 0.61 to 1.0 μm, and the cyan thermal transfer recording layer and the magenta thermal transfer recording layer have a thickness of 0.2 to 0.6 μm. The thermal transfer recording medium according to claim 2 . The thermal transfer recording medium according to claim 1, wherein the fine particles are silica. A method of forming an image with a thermal head printer using the thermal transfer recording medium according to claim 1, wherein the thermal transfer recording layer of the thermal transfer recording medium is thermally transferred onto an image receiving member based on image data, and is based on area gradation. A step of forming an image, and a layer containing an amorphous organic polymer of the same type as the amorphous organic polymer contained in the thermal transfer recording layer is provided on the image receiving surface of the image receiving body. An image forming method. And a thermal transfer recording layer of a plurality of colors repeatedly provided for each color along the longitudinal direction of the support. The thermal transfer recording layer has a color pigment and a softening point of 70 to The thermal transfer recording layer of the plurality of colors including an amorphous organic polymer composed of an epoxy resin having an epoxy equivalent of 600 to 5000 and a molecular weight of 800 to 5000, and fine particles, which is sequentially transferred , It is a thermal transfer recording layer of at least three colors of cyan, magenta, and yellow, and in these three colors, the average layer thickness for each color of the thermal transfer recording layer other than the thermal transfer recording layer of the color to be transferred last is 0.6 μm A thermal transfer recording medium comprising: The thermal transfer recording medium according to claim 6 , wherein 80% by weight or more of the colored pigment is an organic pigment. The average particle size of the color pigment contained in the thermal transfer recording layer is 0.5 μm or less, and the ratio of the color pigment having a particle size exceeding 1 μm in the particle size distribution is 10% or less. The thermal transfer recording medium according to claim 6 . The thermal transfer recording medium according to claim 6 , wherein the thermal transfer recording layer contains no crystalline wax. A method of forming an image by a thermal head printer using the thermal transfer recording medium according to claim 6 , wherein the thermal transfer recording layer of the thermal transfer recording medium is thermally transferred onto an image receiving body based on image data, and is based on area gradation. A step of forming an image, and a layer containing an amorphous organic polymer of the same type as the amorphous organic polymer contained in the thermal transfer recording layer is provided on the image receiving surface of the image receiving member. An image forming method.

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