JP4407184B2

JP4407184B2 - Reversible multicolor recording medium and recording method using the same

Info

Publication number: JP4407184B2
Application number: JP2003271275A
Authority: JP
Inventors: 研一栗原; 寿憲坪井; 典之岸井
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2003-07-07
Filing date: 2003-07-07
Publication date: 2010-02-03
Anticipated expiration: 2023-07-07
Also published as: JP2005028770A

Description

本発明は画像またはデータを記録するための可逆性多色記録媒体、及びこれを用いた記録方法に関わる。 The present invention relates to a reversible multicolor recording medium for recording an image or data, and a recording method using the same.

近年、地球環境的な見地から、リライタブル記録技術の必要性が強く認識されている。コンピューターのネットワーク技術、通信技術、ＯＡ機器、記録メディア、記憶メディア等の進歩を背景としてオフィスや家庭でのペーパーレス化が進んでいる。 In recent years, the necessity of rewritable recording technology has been strongly recognized from the viewpoint of the global environment. With the progress of computer network technology, communication technology, OA equipment, recording media, storage media, etc., paperless is progressing in offices and homes.

印刷物に替わる表示媒体の一例として、熱により可逆的に情報の記録や消去が可能な記録媒体、いわゆる可逆性感熱記録媒体が、各種プリペイドカード、ポイントカード、クレジットカード、ＩＣカード等の普及に伴い、残額やその他の記録情報等の可視化、可読化の用途において実用化されており、さらには複写機及びプリンター等の用途においても実用化されつつある。 As an example of a display medium that replaces printed matter, a recording medium capable of reversibly recording and erasing information by heat, a so-called reversible thermosensitive recording medium, has been widely used for various types of prepaid cards, point cards, credit cards, IC cards, In addition, it has been put into practical use in applications such as visualization and reading of balances and other recorded information, and further in applications such as copying machines and printers.

上記のような可逆性感熱記録媒体及びこれを用いた記録方法に関しては、従来においても各種提案がなされている（例えば、特許文献１〜４参照。）。これらは、いわゆる低分子分散タイプ、すなわち樹脂母材中に有機低分子物質を分散させた記録媒体であり、熱履歴により光の散乱を変化させ、記録層を白濁あるいは透明状態に変化させるものであるため、画像形成部と画像未形成部のコントラストが不充分であるという欠点を有しているため、記録層の下に反射層を設けることによりコントラストを向上させた媒体のみが実用化されている。 Various proposals have heretofore been made regarding the reversible thermosensitive recording medium and the recording method using the same (for example, see Patent Documents 1 to 4). These are so-called low-molecular dispersion types, that is, recording media in which organic low-molecular substances are dispersed in a resin base material, which changes the scattering of light by the thermal history and changes the recording layer to cloudy or transparent. Therefore, since the contrast between the image forming portion and the image non-forming portion is insufficient, only a medium whose contrast is improved by providing a reflective layer under the recording layer has been put into practical use. Yes.

一方、ロイコ染料タイプ、すなわち樹脂母材中に電子供与性呈色性化合物であるロイコ染料と、顕・減色剤とが分散された記録層を有する記録媒体、及びこれを用いた記録方法についての開示がなされている（例えば、特許文献５〜９参照。）。これらにおいて、顕・減色剤としては、ロイコ染料を発色させる酸性基と、発色したロイコ染料を消色させる塩基性基を有する両性化合物、または長鎖アルキルをもつフェノール化合物等が用いられている。この記録媒体及び記録方法は、ロイコ染料自体の発色を利用するため、低分子分散タイプに比較してコントラスト、視認性が良好であり、近年広く実用化されつつある。 On the other hand, a leuco dye type, that is, a recording medium having a recording layer in which a leuco dye that is an electron donating color developing compound and a developer / color-reducing agent are dispersed in a resin base material, and a recording method using the same Disclosure has been made (see, for example, Patent Documents 5 to 9). In these, as the developer / color-reducing agent, an amphoteric compound having an acidic group for developing a leuco dye and a basic group for decoloring the developed leuco dye, a phenol compound having a long-chain alkyl, or the like is used. Since this recording medium and recording method utilize the color developed by the leuco dye itself, the recording medium and the recording method have better contrast and visibility than the low molecular dispersion type, and have been widely put into practical use in recent years.

上記各特許文献により開示されている従来技術においては、母材の材料の色すなわち地肌の色と、熱により変色した色の２種類の色のみしか表現することができない。しかし近年では、視認性やファッション性向上のために、多色画像の表示や各種データを色識別して記録したりすることへの要求が非常に高まっている。
これに対し、上記従来方法を応用し、かつ多色画像の表示を行う記録方法が種々提案されている。 In the prior art disclosed in each of the above patent documents, only two types of colors, that is, the color of the base material, that is, the background color, and the color changed by heat can be expressed. However, in recent years, in order to improve visibility and fashionability, there has been a great demand for displaying multicolor images and recording various data by color identification.
On the other hand, various recording methods that apply the above-described conventional method and display a multicolor image have been proposed.

例えば、多色に塗り分けられた層や粒子を、低分子分散タイプの記録層で可視化あるいは隠蔽することで、多色表示を行う記録媒体、及びこれを用いた記録方法が開示されている（特許文献１０〜１２参照。）。しかしこのような構成の記録媒体においては、記録層が下層の色を完全に隠蔽することはできず、母材の色が透けてしまい、高いコントラストが得られなかった。 For example, a recording medium that performs multicolor display by visualizing or concealing layers and particles separately coated in multiple colors with a low molecular dispersion type recording layer, and a recording method using the same are disclosed ( (See Patent Documents 10 to 12.) However, in the recording medium having such a configuration, the recording layer cannot completely hide the color of the lower layer, the color of the base material is transparent, and high contrast cannot be obtained.

また、ロイコ染料を用いた可逆性感熱多色記録媒体について、その他の開示もなされているが（例えば、特許文献１３、１４参照。）、これらは面内に色相の異なる繰り返し単位を有するものであるため、各色相が実際に記録される面積比が小さいため、記録した画像は非常に暗い、または薄い画像しか得ることはできないという問題がある。 Although other disclosures have been made on reversible thermosensitive multicolor recording media using leuco dyes (see, for example, Patent Documents 13 and 14), these have repeating units having different hues in the plane. Therefore, since the area ratio in which each hue is actually recorded is small, there is a problem that a recorded image can be obtained only in a very dark or thin image.

また、発色温度、消色温度、冷却速度等が異なるロイコ染料を用いた記録層を分離、独立した状態で形成された構成の可逆性感熱多色記録媒体に関する開示もなされている（例えば、特許文献１５〜２３参照。）。
しかし、サーマルヘッド等の記録熱源による温度コントロールが困難な上、良好なコントラストが得られず、色のかぶりを避けられないという問題を有している。さらには、三色以上の多色化をサーマルヘッド等による加熱温度及び／または加熱後の冷却速度の違いのみでコントロールするのは非常に困難である。 Also disclosed is a reversible thermosensitive multicolor recording medium having a structure in which recording layers using leuco dyes having different color development temperature, decoloring temperature, cooling rate, etc. are separated and formed independently (for example, patents). Reference 15-23).
However, there are problems that it is difficult to control the temperature with a recording heat source such as a thermal head, a good contrast cannot be obtained, and color fog cannot be avoided. Furthermore, it is very difficult to control the increase of three or more colors only by the difference in heating temperature and / or cooling rate after heating with a thermal head or the like.

また、ロイコ染料を用いた記録層を、分離、独立した状態で形成した構成の可逆性感熱多色記録媒体において、レーザー光の照射による光−熱変換により任意の記録層のみを加熱し、発色させる記録方法に関する開示もなされている（例えば、特許文献２４参照。）。この方法によれば、光−熱変換層の波長選択性の効果により、任意の記録層のみを発色させることができ、従来の可逆性多色記録媒体で問題であった、色のかぶりの問題が解決できる可能性がある。
しかし、この可逆性感熱多色記録媒体は、光−熱変換層と記録層とが別個独立して設けられているため、構成層数が多くなり、製造プロセスが複雑化するという問題を有している。さらには、レーザー光照射により光−熱変換されたエネルギーが記録層に効率良く伝わらず、充分な発色が得られず、記録に要する時間が長くなる等の問題があった。 In addition, in a reversible thermosensitive multicolor recording medium having a structure in which a recording layer using a leuco dye is separated and formed independently, only an arbitrary recording layer is heated by light-to-heat conversion by laser light irradiation, and color development The recording method to be performed is also disclosed (for example, refer to Patent Document 24). According to this method, due to the wavelength selectivity effect of the light-to-heat conversion layer, only an arbitrary recording layer can be colored, and the problem of color fog, which has been a problem with conventional reversible multicolor recording media. May be resolved.
However, this reversible thermosensitive multicolor recording medium has a problem that the number of constituent layers is increased and the manufacturing process is complicated because the light-heat conversion layer and the recording layer are provided separately and independently. ing. Furthermore, there is a problem that energy converted into light by heat by laser light irradiation is not efficiently transmitted to the recording layer, sufficient color development is not obtained, and the time required for recording becomes long.

特開昭５４−１１９３７７号公報、JP-A-54-119377, 特開昭５５−１５４１９８号公報JP 55-154198 A 特開昭６３−３９３７７号公報JP-A-63-39377 特開昭６３−４１１８６号公報JP-A-63-41186 特開平２−１８８２９３号公報JP-A-2-188293 特開平２−１８８２９４号公報JP-A-2-188294 特開平５−１２４３６０号公報JP-A-5-124360 特開平７−１０８７６１号公報Japanese Patent Laid-Open No. 7-108761 特開平７−１８８２９４号公報JP 7-188294 A 特開平５−６２１８９号公報Japanese Patent Laid-Open No. 5-62189 特開平８−８０６８２号公報JP-A-8-80682 特開２０００−１９８２７５号公報JP 2000-198275 A 特開平８−５８２４５号公報JP-A-8-58245 特開２０００−２５３３８号公報JP 2000-25338 A 特開平６−３０５２４７号公報JP-A-6-305247 特開平６−３２８８４４号公報JP-A-6-328844 特開平６−７９９７０号公報JP-A-6-79970 特開平８−１６４６６９号公報JP-A-8-164669 特開平８−３００８２５号公報JP-A-8-300825 特開平９−５２４４５号公報Japanese Patent Laid-Open No. 9-52445 特開平１１−１３８９９７号公報JP 11-138997 A 特開２００１−１６２９４１号公報JP 2001-162941 A 特開２００２−５９６５４号公報JP 2002-59654 A 特開２００１−１６４５号公報JP 2001-1645 A

上述したように多色感熱記録への要望は大きく、従来においても種々の研究が盛んに行われているが、実用的に満足できる記録媒体、あるいは記録方式は未だ実現されていない。 As described above, there is a great demand for multicolor thermal recording, and various studies have been actively conducted in the past, but a recording medium or a recording method that is practically satisfactory has not yet been realized.

そこで本発明においては、このような従来技術の問題に鑑みて、安定な発消色、コントラストを有し、かつ日常生活においても実用上優れた画像安定性を実現でき、任意の色調を発色・消去可能な可逆性多色感熱記録媒体、及びこれを用いた記録方法を提供する。 Therefore, in the present invention, in view of such problems of the prior art, stable color development / contrast, contrast, and practically excellent image stability can be realized in daily life. An erasable reversible multicolor thermal recording medium and a recording method using the same are provided.

本発明においては、支持基板の面方向に、可逆的に異なる色調に発色する複数の記録層が、それぞれ分離・積層形成された構成を有し、記録層には、少なくとも、それぞれ異なる波長域の赤外線を吸収して発熱する光−熱変換材料と、電子供与性を有する呈色性化合物と、電子受容性を有し、下記一般式（３）で表される化合物の少なくとも一種よりなる顕・減色剤と、下記一般式（２）で表される化合物の少なくとも一種よりなる増感剤と、塩化ビニル酢酸ビニル共重合体よりなるポリマーとが含有されてなり、呈色性化合物と、顕・減色剤との間の可逆的反応により、各記録層を、発色、消色の二状態に可逆的に変化可能とした可逆性多色記録媒体を提供する。
In the present invention, a plurality of recording layers that color reversibly in different color tones in the surface direction of the support substrate are respectively separated and laminated, and the recording layers have at least different wavelength ranges. A light-to-heat conversion material that generates heat by absorbing infrared rays, a color-forming compound having electron donating properties, and an electron-accepting and at least one compound represented by the following general formula (3) A color-reducing agent, a sensitizer composed of at least one compound represented by the following general formula (2), and a polymer composed of a vinyl chloride / vinyl acetate copolymer are contained, and a color developing compound, Provided is a reversible multicolor recording medium in which each recording layer can be reversibly changed into two states of color development and decoloration by a reversible reaction with a color reducing agent.

但し、Ｒ４は、炭素数１８の炭化水素基であるものとする。
However, R4 shall be a C18 hydrocarbon group.

ＨＯ−Ｒ3−ＯＨ・・・（２）
但し、Ｒ3は、炭素数１８，２４のいずれかの炭化水素基であるものとする。
HO-R3-OH (2)
However, R3 is assumed to be any hydrocarbon group having 18 or 24 carbon atoms.

また、本発明の記録方法においては、支持基板の面方向に、可逆的に異なる色調に発色する複数の記録層が、それぞれ分離・積層形成されてなり、記録層には、少なくとも、それぞれ異なる波長域の赤外線を吸収して発熱する光−熱変換材料と、電子供与性を有する呈色性化合物と、電子受容性を有し、下記一般式（３）で表される化合物の少なくとも一種よりなる顕・減色剤と、下記一般式（２）で表される化合物の少なくとも一種よりなる増感剤と、塩化ビニル酢酸ビニル共重合体よりなるポリマーとが含有されてなり、呈色性化合物と、顕・減色剤との間の可逆的反応により、記録層が、発色、消色の二状態に可逆的に変化可能とした可逆性多色記録媒体を用いて、加熱処理を施して予め記録層全体を消色状態にしておき、所望の画像情報に応じ、記録層のうちの選択されたものに対応して選択された波長領域の赤外線を照射して露光を行い、記録層を発熱せしめ、選択的に発色化させることにより、画像情報の記録を行うものとする。
In the recording method of the present invention, a plurality of recording layers that reversibly develop different color tones in the surface direction of the support substrate are respectively separated and laminated, and the recording layers have at least different wavelengths. A light-to-heat conversion material that absorbs infrared rays and generates heat, a color-forming compound having an electron donating property, and an electron-accepting compound that includes at least one compound represented by the following general formula (3) A developer / color-reducing agent, a sensitizer composed of at least one compound represented by the following general formula (2), and a polymer composed of a vinyl chloride / vinyl acetate copolymer , A reversible reaction between the developer and the color reducing agent allows the recording layer to be reversibly changed into two states of color development and color erasing, and is subjected to a heat treatment in advance. Leave the entire image decolored and the desired image In response to the information, exposure is performed by irradiating infrared rays of a wavelength region selected corresponding to the selected one of the recording layers, and the recording layer is heated to selectively develop color, thereby generating image information. Records shall be made.

また、本発明の記録方法においては、支持基板の面方向に、可逆的に異なる色調に発色する複数の記録層が、分離・積層形成されてなり、記録層には、少なくとも、それぞれ異なる波長域の赤外線を吸収して発熱する光−熱変換材料と、電子供与性を有する呈色性化合物と、電子受容性を有し、一般式（３）で表される化合物の少なくとも一種よりなる顕・減色剤と、一般式（２）で表される化合物の少なくとも一種よりなる増感剤と、塩化ビニル酢酸ビニル共重合体よりなるポリマーとが含有されてなり、呈色性化合物と、顕・減色剤との間の可逆的反応により、記録層が発色、消色の二状態に可逆的に変化するようになされている可逆性多色記録媒体を用いて、加熱処理を施して予め記録層全体を発色状態にしておき、所望の画像情報に応じ、記録層のうちの選択されたものに対応して選択された波長領域の赤外線を照射して露光を行い、記録層を発熱せしめ、選択的に消色化することにより、画像情報の記録を行うものとする。
In the recording method of the present invention, a plurality of recording layers that reversibly develop different color tones in the surface direction of the support substrate are separated and laminated, and the recording layers have at least different wavelength ranges. A light-to-heat conversion material that absorbs infrared rays to generate heat, a color-forming compound having electron donating properties, and an electron-accepting and at least one compound represented by the general formula (3) A color-reducing agent, a sensitizer comprising at least one compound represented by the general formula (2), and a polymer comprising a vinyl chloride / vinyl acetate copolymer are contained. The recording layer is preliminarily subjected to heat treatment using a reversible multicolor recording medium in which the recording layer is reversibly changed into two states of color development and decoloration by a reversible reaction with the agent. Leave it in a colored state for the desired image information. The recording of image information is performed by irradiating with infrared rays in a wavelength region selected corresponding to the selected one of the recording layers, exposing the recording layer to heat, and selectively decoloring. Shall be performed.

本発明によれば、適用する顕・減色剤の化学式の構成、及び増感剤の構成を制御することにより、溶媒やポリマーへの溶解性、融点、発色・消色可能な温度等の各種条件の調整が可能となり、記録、及び消去の低エネルギー化、及び記録感度の向上が図られる。 According to the present invention, by controlling the constitution of the chemical formula of the developing / subtracting agent to be applied and the constitution of the sensitizer, various conditions such as solubility in a solvent or polymer, melting point, temperature at which coloring / decoloring is possible, etc. Thus, the energy of recording and erasing can be reduced, and the recording sensitivity can be improved.

本発明によれば、記録層中に含有される顕・減色剤及び増感剤を、任意の化学構造を有するものに特定したことにより、波長選択した赤外線を照射した場合に任意の記録層を的確に発熱せしめ、可逆的な発色状態と消色状態との変換を、迅速かつ高精度に行うことができ、これによって繰り返して情報の記録、及び消去を行う際に、優れた発色性、コントラスト、精細さが得られ、極めて感度の高い可逆性多色記録媒体を得ることができた。 According to the present invention, since the developer / desensitizer and sensitizer contained in the recording layer are specified as those having an arbitrary chemical structure, an arbitrary recording layer can be formed when irradiated with wavelength-selected infrared rays. It generates heat accurately and can convert between a reversible coloring state and a decoloring state quickly and with high accuracy. This ensures excellent color development and contrast when recording and erasing information repeatedly. Thus, it was possible to obtain a reversible multicolor recording medium with high definition and extremely high sensitivity.

また本発明によれば、安定かつ鮮明な発消色、明瞭なコントラストが得られ、実用上充分な画像安定性を有し、更には高速記録・高速消去可能な記録方法が実現できた。 Further, according to the present invention, a stable and clear color erasing and decoloring and clear contrast can be obtained, and a recording method capable of high-speed recording and high-speed erasing can be realized with practically sufficient image stability.

以下、本発明の具体的な実施の形態について図面を参照して説明するが、本発明の可逆性多色記録媒体は、以下の例に限定されるものではない。
図１に本発明における可逆性多色記録媒体の概略断面図を示す。
可逆性多色記録媒体１０は、支持基板１上に、第１の記録層１１、第２の記録層１２、及び第３の記録層１３が、それぞれ断熱層１４、１５を介して積層されており、最上層に保護層１６が形成された構成を有している。 Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the reversible multicolor recording medium of the present invention is not limited to the following examples.
FIG. 1 is a schematic sectional view of a reversible multicolor recording medium according to the present invention.
In the reversible multicolor recording medium 10, a first recording layer 11, a second recording layer 12, and a third recording layer 13 are laminated on a support substrate 1 via heat insulating layers 14 and 15, respectively. The protective layer 16 is formed as the uppermost layer.

支持基板１は、耐熱性に優れ、かつ平面方向の寸法安定性の高い材料であれば従来公知の材料を適宜使用することができる。例えばポリエステル、硬質塩化ビニル等の高分子材料の他、ガラス材料、ステンレス等の金属材料、あるいは紙等の材料から適宜選択できる。ただしオーバーヘッドプロジェクター等の透過用途以外では、支持基板１は最終的に得られる可逆性多色記録媒体１０に対して情報の記録を行った際の視認性の向上を図るため、白色、あるいは金属色を有する可視光に対する反射率の高い材料によって形成することが好ましい。 As the support substrate 1, a conventionally known material can be appropriately used as long as the material has excellent heat resistance and high dimensional stability in the planar direction. For example, it can be appropriately selected from polymer materials such as polyester and hard vinyl chloride, glass materials, metal materials such as stainless steel, and materials such as paper. However, except for transmission applications such as overhead projectors, the support substrate 1 is white or metallic in order to improve the visibility when information is recorded on the finally obtained reversible multicolor recording medium 10. It is preferable to form with the material which has high reflectance with respect to visible light which has.

第１〜第３の記録層１１〜１３は、安定した繰り返し記録が可能な、消色状態と発色状態とを制御し得る材料を用いて形成する。
第１〜第３の記録層１１〜１３には、それぞれ異なる波長の赤外線（図１中λ₁、λ₂、λ₃）を吸収して発熱する光−熱変換材料が含有されている。
また、第１〜第３の記録層１１〜１３には、それぞれ、電子供与性を有する呈色性化合物、例えばロイコ染料と、所定の電子受容性を有する顕・減色剤と、増感剤とが含有されてなるものとし、これらを樹脂母材中に分散させた塗料を塗布することによって形成されたものとする。 The first to third recording layers 11 to 13 are formed using a material capable of controlling a decoloring state and a coloring state, which enables stable repeated recording.
The first to third recording layers 11 to 13 contain light-heat conversion materials that generate heat by absorbing infrared rays having different wavelengths (λ ₁ , λ ₂ , λ _{3 in} FIG. 1).
The first to third recording layers 11 to 13 each have a color-forming compound having an electron donating property, such as a leuco dye, a developer / color-reducing agent having a predetermined electron accepting property, and a sensitizer. And is formed by applying a paint in which these are dispersed in a resin base material.

また、第１〜第３の記録層１１〜１３は、それぞれが発色する所望の色に応じ、所定のロイコ染料を用いて形成する。例えば第１〜第３の記録層１１〜１３において三原色を発色するようにすれば、この可逆性多色記録媒体１０全体としてフルカラー画像の形成が可能になる。 Further, the first to third recording layers 11 to 13 are formed using a predetermined leuco dye according to a desired color to be colored. For example, if the three primary colors are developed in the first to third recording layers 11 to 13, a full color image can be formed as the entire reversible multicolor recording medium 10.

電子供与性を有する呈色性化合物であるロイコ染料としては、例えば、既存の感熱紙用染料等を適用することができる。 As the leuco dye, which is a color-forming compound having an electron donating property, for example, an existing thermal paper dye can be applied.

また、電子受容性を有する顕・減色剤としては、下記一般式（１）で表される化合物の少なくとも一種を適用する。 In addition, as the developer / subtractor having electron acceptability, at least one compound represented by the following general formula (1) is applied.

但し、Ｘは、ＯＨ、ＣＯＯＨ、ハロゲン、Ｈのいずれかよりなり、Ｙは、−ＮＨＣＯ−、−ＣＯＮＨ−、−ＮＨＣＯＮＨ−、−ＣＯＮＨＣＯ−、−ＮＨＮＨＣＯ−、−ＣＯＮＨＮＨ−、−ＣＯＮＨＮＨＣＯ−、−ＮＨＣＯＣＯＮＨ−、−ＮＨＣＯＮＨＣＯ−、−ＣＯＮＨＣＯＮＨ−、−ＮＨＮＨＣＯＮＨ−、−ＮＨＣＯＮＨＮＨ−、−ＣＯＮＨＮＨＣＯＮＨ−、−ＮＨＣＯＮＨＮＨＣＯ−、−ＣＯＮＨＮＨＣＯＮＨ−のいずれかよりなり、Ｒ1、Ｒ2は、それぞれ炭素数２〜２６の炭化水素基であり、かつＲ１、Ｒ２の炭素数の合計が９以上、３０以下であり、Ｚは、−ＣＯＯ−、−ＯＣＯ−、−Ｏ−、−ＣＯＮＨ−、−ＮＨＣＯ−、−ＮＨＣＯＮＨ−、−ＮＨＮＨＣＯ−、−ＣＯＮＨＮＨ−、−ＣＨ（Ｃ_nＨ_2nＯＨ）−（但し、ｎ＝０〜５）のいずれかよりなり、ａは０又は１であるものとする。 However, X consists of any of OH, COOH, halogen, and H, and Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-,- NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, -CONHNHCONH-, R1 and R2 are each a hydrocarbon having 2 to 26 carbon atoms And the total number of carbon atoms of R 1 and R 2 is 9 or more and 30 or less, and Z is —COO—, —OCO—, —O—, —CONH—, —NHCO—, —NHCONH—, — NHNHCO -, - CONHNH -, - CH (C n H 2n OH) - ( where, n = 0 to 5) Either be more, a is assumed to be 0 or 1.

電子受容性を有する顕・減色剤の化学式を構成するＸ、Ｙ、Ｚ、Ｒ1、Ｒ2は、目的とする可逆性多色記録媒体１０に要求される記録・消去感度、すなわち溶媒やポリマーへの溶解性、融点、発色・消色可能な温度等の各種条件応じて適宜選定し、組み合わせるものとする。
例えば、電子受容性を有する顕・減色剤の好適な例として、下記一般式（３）で表される化合物が挙げられる。 X, Y, Z, R 1 and R 2 constituting the chemical formula of the developer / subtractor having electron accepting properties are the recording / erasing sensitivities required for the intended reversible multicolor recording medium 10, that is, to the solvent or polymer. They shall be appropriately selected and combined according to various conditions such as solubility, melting point, color developing / decoloring temperature, and the like.
For example, a compound represented by the following general formula (3) may be mentioned as a suitable example of the developing / color-reducing agent having electron accepting properties.

但し、上記一般式（３）において、Ｒ4は、分子間の凝集作用の低減化を防止し、かつ溶媒やポリマーへの溶解性の悪化を回避するために、炭素数が８〜２４、さらには１４〜２０程度の炭化水素基であることが望ましい。 However, in the above general formula (3), R4 has 8 to 24 carbon atoms in order to prevent a decrease in aggregation action between molecules and avoid deterioration of solubility in a solvent or polymer. A hydrocarbon group of about 14 to 20 is desirable.

また、増感剤としては、下記一般式（２）で表される化合物の少なくとも一種よりなる化合物を適用する。この増感剤は、記録消去温度を低下させて消去感度を向上させたり、発色温度を低下させて記録感度を向上させたりし、より低エネルギーで記録、及び消去を可能にする効果を有する。 Moreover, as a sensitizer, the compound which consists of at least 1 type of the compound represented by following General formula (2) is applied. This sensitizer has the effect of enabling recording and erasing with lower energy by lowering the recording and erasing temperature to improve the erasing sensitivity and lowering the color development temperature to improve the recording sensitivity.

ＨＯ−Ｒ3−ＯＨ・・・（２）
但し、Ｒ3は、炭素数１０〜２４の炭化水素基であるものとする。Ｒ3の炭素数が２５以上になると、溶媒やポリマーへの溶解性が悪化し、記録層の透明性が損なわれ、一方、炭素数が９以下になると融点が低下しすぎ、充分な発色安定性が得られないため、炭素数は１０〜２４が好適であり、更に望ましくは１６〜２０であるものとする。 HO-R3-OH (2)
R3 is a hydrocarbon group having 10 to 24 carbon atoms. When the carbon number of R3 is 25 or more, the solubility in a solvent or polymer is deteriorated, and the transparency of the recording layer is impaired. On the other hand, when the carbon number is 9 or less, the melting point is excessively lowered and sufficient color stability is obtained. Is not obtained, the carbon number is preferably 10 to 24, and more preferably 16 to 20.

第１〜第３の記録層１１〜１３は、それぞれ異なる波長域に吸収をもつ光−熱変換材料を含有しているものとする。
光−熱変換材料としては、例えば、第１の記録層１１が波長λ₁の赤外線を、第２の記録層１２が波長λ₂の赤外線を、第３の記録層１３が波長λ₃の赤外線をそれぞれ吸収して発熱する材料が適用できる。 The first to third recording layers 11 to 13 contain light-to-heat conversion materials having absorption in different wavelength ranges.
As the light-heat conversion material, for example, the first recording layer 11 emits infrared light with a wavelength λ ₁ , the second recording layer 12 emits infrared light with a wavelength λ ₂ , and the third recording layer 13 emits infrared light with a wavelength λ ₃ . A material that absorbs heat and generates heat can be applied.

第１〜第３の記録層１１〜１３内に含有される光−熱変換材料としては、例えば、可視波長域にほとんど吸収がない赤外線吸収色素として一般的に用いられる、フタロシアニン系染料やシアニン系染料、金属錯体染料、ジインモニウム系染料等を適用できる。
さらには、任意の光−熱変換材料のみを発熱させるために、光吸収帯が狭く、互いに重なり合わない材料の組み合わせを選択することが好ましい。 Examples of the light-to-heat conversion material contained in the first to third recording layers 11 to 13 include, for example, phthalocyanine dyes and cyanine dyes that are generally used as infrared absorbing dyes that hardly absorb in the visible wavelength range. Dyes, metal complex dyes, diimonium dyes, and the like can be applied.
Furthermore, in order to generate heat only in an arbitrary light-heat conversion material, it is preferable to select a combination of materials having a narrow light absorption band and not overlapping each other.

第１〜第３の記録層１１〜１３形成用の樹脂としては、例えばポリ塩化ビニル、ポリ酢酸ビニル、塩化ビニル−酢酸ビニル共重合体、エチルセルロース、ポリスチレン、スチレン系共重合体、フェノキシ樹脂、ポリエステル、芳香族ポリエステル、ポリウレタン、ポリカーボネート、ポリアクリル酸エステル、ポリメタクリル酸エステル、アクリル酸系共重合体、マレイン酸系重合体、ポリビニルアルコール、変性ポリビニルアルコール、ヒドロキシエチルセルロース、カルボキシメチルセルロース、デンプン等が挙げられる。これらの樹脂に必要に応じて紫外線吸収剤等の各種添加剤を併用してもよい。 Examples of the resin for forming the first to third recording layers 11 to 13 include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethyl cellulose, polystyrene, styrene copolymer, phenoxy resin, and polyester. , Aromatic polyester, polyurethane, polycarbonate, polyacrylic acid ester, polymethacrylic acid ester, acrylic acid copolymer, maleic acid polymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, starch and the like. . Various additives such as an ultraviolet absorber may be used in combination with these resins as necessary.

第１〜第３の記録層１１〜１３は、上記ロイコ染料、顕・減色剤、光−熱変換材料と各種添加剤とを溶媒を用いて上記樹脂中に溶解させた塗料を、それぞれの所定の形成面に塗布することによって形成することができる。使用する溶媒は、顕・減色剤の溶解性が高いものが好ましい。 Each of the first to third recording layers 11 to 13 is formed of a coating material obtained by dissolving the leuco dye, the developing / color-reducing agent, the light-heat conversion material and various additives in the resin using a solvent. It can form by apply | coating to the formation surface. The solvent to be used is preferably a solvent having high solubility of the developer / color reducing agent.

第１〜第３の記録層１１〜１３は、それぞれ膜厚１〜２０μｍ程度に形成することが望ましく、更には３〜１５μｍ程度が望ましい。これらの膜厚が１μｍ未満であると充分な発色濃度が得られず、２０μｍを超えた膜厚になると記録層１１〜１３の熱容量が大きくなり、発色性や消色性が劣化するためである。 The first to third recording layers 11 to 13 are each preferably formed to a thickness of about 1 to 20 μm, and more preferably about 3 to 15 μm. If these film thicknesses are less than 1 μm, a sufficient color density cannot be obtained, and if the film thickness exceeds 20 μm, the heat capacity of the recording layers 11 to 13 increases, and the color developability and decoloring properties deteriorate. .

第１の記録層１１と第２の記録層１２との間、第２の記録層１２と第３の記録層１３との間には、それぞれ透光性の断熱層１４、１５を形成することが望ましい。これによって隣接する記録層からの熱伝導が回避され、いわゆる色かぶりの発生を防止することができる。 Translucent heat insulating layers 14 and 15 are formed between the first recording layer 11 and the second recording layer 12 and between the second recording layer 12 and the third recording layer 13, respectively. Is desirable. As a result, heat conduction from the adjacent recording layer is avoided, and so-called color fogging can be prevented.

断熱層１４、１５は、従来公知の透光性のポリマーを用いて形成することができる。例えば、ポリ塩化ビニル、ポリ酢酸ビニル、塩化ビニル−酢酸ビニル共重合体、エチルセルロース、ポリスチレン、スチレン系共重合体、フェノキシ樹脂、ポリエステル、芳香族ポリエステル、ポリウレタン、ポリカーボネート、ポリアクリル酸エステル、ポリメタクリル酸エステル、アクリル酸系共重合体、マレイン酸系重合体、ポリビニルアルコール、変性ポリビニルアルコール、ヒドロキシエチルセルロース、カルボキシメチルセルロース、デンプン等が挙げられる。これらのポリマーには必要に応じて紫外線吸収剤等の各種添加剤を併用してもよい。 The heat insulation layers 14 and 15 can be formed using a conventionally known translucent polymer. For example, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethyl cellulose, polystyrene, styrene copolymer, phenoxy resin, polyester, aromatic polyester, polyurethane, polycarbonate, polyacrylic acid ester, polymethacrylic acid Examples include esters, acrylic acid copolymers, maleic acid polymers, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, and starch. These polymers may be used in combination with various additives such as ultraviolet absorbers as necessary.

また、断熱層１４、１５は透光性の無機膜を用いて形成することもできる。例えば、多孔質のシリカ、アルミナ、チタニア、カーボン、またはこれらの複合体等を用いると、熱伝導率が低くなり断熱効果が高く好ましい。これらは液層から膜形成できるゾル−ゲル法によって形成することができる。 Moreover, the heat insulation layers 14 and 15 can also be formed using a translucent inorganic film. For example, use of porous silica, alumina, titania, carbon, or a composite thereof is preferable because the thermal conductivity is lowered and the heat insulating effect is high. These can be formed by a sol-gel method capable of forming a film from a liquid layer.

断熱層１４、１５は、膜厚３〜１００μｍ程度に形成することが望ましく、さらには５〜５０μｍ程度に形成することが好ましい。これらの膜厚が薄すぎると充分な断熱効果が得られず、膜厚が厚すぎると、後述する記録方法において記録媒体全体を均一加熱する際に熱伝導性が劣化したり、透光性が低下したりするためである。 The heat insulating layers 14 and 15 are preferably formed to a thickness of about 3 to 100 μm, and more preferably about 5 to 50 μm. If these film thicknesses are too thin, a sufficient heat insulating effect cannot be obtained, and if the film thickness is too thick, the thermal conductivity deteriorates when the entire recording medium is uniformly heated in the recording method to be described later, or the translucency is low. It is because it falls.

保護層１６は、従来公知の紫外線硬化性樹脂や熱硬化性樹脂を用いて形成することができ、膜厚は０．１〜２０μｍ、さらには０．５〜５μｍ程度とすることが望ましい。
保護層１６の膜厚が０．１μｍ未満であると充分な保護効果が得られず、一方、２０μｍを超えた膜厚にすると熱伝導性が悪化するという不都合を生じるためである。 The protective layer 16 can be formed using a conventionally known ultraviolet curable resin or thermosetting resin, and the film thickness is preferably about 0.1 to 20 μm, more preferably about 0.5 to 5 μm.
This is because if the film thickness of the protective layer 16 is less than 0.1 μm, a sufficient protective effect cannot be obtained, whereas if the film thickness exceeds 20 μm, there is a disadvantage that the thermal conductivity deteriorates.

次に、図１に示した可逆性多色記録媒体１０を用いて、多色記録を行う原理について説明する。 Next, the principle of performing multicolor recording using the reversible multicolor recording medium 10 shown in FIG. 1 will be described.

先ず、多色記録の第１の原理を説明する。
図１に示した可逆性多色記録媒体１０を、各記録層が消色する程度の温度、例えば１２０℃程度の温度で全面加熱し、第１〜第３の記録層１１〜１３を予め消色状態にしておく。すなわちこの状態においては、支持基板１の色が露出している状態となっているものとする。 First, the first principle of multicolor recording will be described.
The reversible multicolor recording medium 10 shown in FIG. 1 is entirely heated at a temperature at which each recording layer is erased, for example, at a temperature of about 120 ° C., and the first to third recording layers 11 to 13 are erased in advance. Leave in color. That is, in this state, it is assumed that the color of the support substrate 1 is exposed.

次に、可逆性多色記録媒体１０の任意の部分に、波長及び出力を任意に選択した赤外線を半導体レーザー等により照射する。
例えば第１の記録層１１を発色させる場合には、波長λ₁の赤外線を第１の記録層１１が発色温度に達する程度のエネルギーで照射し、光−熱変換材料を発熱させて、電子供与性呈色化合物と電子供与性顕・減色剤との間の発色反応を起こさせ、照射部分を発色させる。
同様に、第２の記録層１２及び第３の記録層１３についても、それぞれ波長λ₂、λ₃の赤外線を発色温度に達する程度のエネルギーを照射してそれぞれの光−熱変換材料を発熱させて照射部分を発色させる。
上述したように、可逆性多色記録媒体１０の任意の部分を発色させることができ、フルカラー画像形成や種々の情報の記録が可能となる。 Next, an arbitrary part of the reversible multicolor recording medium 10 is irradiated with infrared light having an arbitrarily selected wavelength and output by a semiconductor laser or the like.
For example, when the first recording layer 11 is colored, an infrared ray having a wavelength λ ₁ is irradiated with energy that the first recording layer 11 reaches the coloring temperature, and the light-to-heat conversion material is heated to donate electrons. The color development reaction between the color developing compound and the electron donating developer / color-reducing agent is caused to color the irradiated portion.
Similarly, the second recording layer 12 and the third recording layer 13 are also irradiated with energy having a wavelength of λ ₂ and λ ₃ to reach the coloring temperature, respectively, so that each light-heat conversion material generates heat. To color the irradiated area.
As described above, an arbitrary portion of the reversible multicolor recording medium 10 can be colored, and a full-color image can be formed and various information can be recorded.

ところで、第１の記録層１１、あるいは第２の記録層１２を記録する際、それらの上層に形成されている記録層の透明性が、下層の記録層の記録感度に大きな影響を及ぼす。すなわち、所定の記録層の上層に形成されている記録層に使用されている顕・減色剤、及び増感剤のポリマー中への溶解性が悪く、記録層が分散白濁しているような場合には、照射した赤外線が上層で反射、散乱されてしまうため、記録感度は著しく低下してしまう。このため、図１に示すような構成を有する積層型の可逆性多色記録媒体１０においては、記録層を形成するための溶媒あるいはポリマーへの溶解性が高い顕・減色剤及び増感剤を使用することが重要である。 By the way, when the first recording layer 11 or the second recording layer 12 is recorded, the transparency of the recording layer formed on the upper layer greatly affects the recording sensitivity of the lower recording layer. That is, when the recording layer is dispersed and cloudy because the solubility of the developer / sensitizer used in the recording layer formed on the upper layer of the predetermined recording layer and the sensitizer in the polymer is poor In this case, since the irradiated infrared rays are reflected and scattered by the upper layer, the recording sensitivity is remarkably lowered. For this reason, in the multilayer reversible multicolor recording medium 10 having the configuration as shown in FIG. 1, a developer / sensitizer and a sensitizer having high solubility in a solvent or polymer for forming a recording layer are used. It is important to use.

また、上記のようにして発色させた所定の記録層において、さらに任意の波長の赤外線を、各記録層１１〜１３が消色温度に達する程度のエネルギーで照射し、光−熱変換材料を発熱させて、呈色化合物と顕・減色剤との間で消色反応を起こさせることによって、記録の消去を行うことができる。 Further, in the predetermined recording layer colored as described above, an infrared ray having an arbitrary wavelength is further irradiated with energy at which each recording layer 11 to 13 reaches the decoloring temperature, and the light-heat conversion material generates heat. Thus, the recording can be erased by causing a decoloring reaction between the coloring compound and the developer / color-reducing agent.

また、上述のようにして一部を着色化させた可逆性多色記録媒体１０の全体を、全ての記録層が消色する程度の温度、例えば１２０℃で一様に加熱することによって、記録情報や画像を消去することができ、その後上述したような操作を行うことにより繰り返し記録が可能である。 Further, the entire reversible multicolor recording medium 10 partially colored as described above is uniformly heated at a temperature at which all the recording layers are decolored, for example, 120 ° C. Information and images can be erased, and recording can be repeated by performing the operations described above.

次に、多色記録の第２の原理を説明する。
先ず、図１に示した可逆性多色記録媒体１０を、各記録層１１〜１３が発色する程度の温度、例えば２００℃程度の高温で全面加熱し、次に冷却し、第１〜第３の記録層１１〜１３を全て予め発色状態にしておく。 Next, the second principle of multicolor recording will be described.
First, the reversible multicolor recording medium 10 shown in FIG. 1 is heated on the entire surface at a temperature at which each of the recording layers 11 to 13 develops color, for example, at a high temperature of about 200 ° C., and then cooled. All of the recording layers 11 to 13 are colored in advance.

次に、可逆性多色記録媒体１０の任意の部分に、波長及び出力を任意に選択した赤外線を半導体レーザー等により照射する。
例えば第１の記録層１１を消色させる場合には、波長λ₁の赤外線を第１の記録層１１が消色する程度のエネルギーで照射し、光−熱変換材料を発熱させて記録層１１を消色状態とする。
同様に、第２の記録層１２及び第３の記録層１３についても、それぞれ波長λ₂、λ₃の赤外線を、消色温度に達する程度のエネルギーで照射してそれぞれの光−熱変換材料を発熱させて照射部分を消色させることができる。
上述のようにすることによって、可逆性多色記録媒体１０の任意の部分を消色させることができ、フルカラー画像形成や種々の情報の記録が可能となる。 Next, an arbitrary part of the reversible multicolor recording medium 10 is irradiated with infrared light having an arbitrarily selected wavelength and output by a semiconductor laser or the like.
For example, when the first recording layer 11 is decolored, the recording layer 11 is irradiated with infrared light having a wavelength λ ₁ with such energy that the first recording layer 11 is decolored to generate heat. Is decolored.
Similarly, the second recording layer 12 and the third recording layer 13 are each irradiated with infrared rays having wavelengths λ ₂ and λ ₃ with energy to reach the decoloring temperature, and the respective light-to-heat conversion materials are applied. The irradiated portion can be decolored by generating heat.
As described above, an arbitrary portion of the reversible multicolor recording medium 10 can be erased, and a full-color image can be formed and various information can be recorded.

上記のようにして消色させた各記録層１１〜１３において、さらに任意の波長の赤外線を、各記録層１１〜１３が発色温度に達する程度のエネルギーで照射し、光−熱変換材料を発熱させて、呈色化合物と顕・減色剤との間の発色反応を起こさせることによって、記録層の任意の部分を発色化させることができる。 In each of the recording layers 11 to 13 decolorized as described above, an infrared ray having an arbitrary wavelength is further irradiated with energy at which the recording layers 11 to 13 reach the coloring temperature, and the light-heat conversion material generates heat. Thus, by causing a color development reaction between the color forming compound and the developer / subtractor, any portion of the recording layer can be colored.

更に、上述のようにして一部を消色化、あるいは発色化させた可逆性多色記録媒体１０の全体を、全ての記録層が着色する程度の温度、例えば２００℃で一様に加熱し、次いで冷却することによって、記録情報や画像を消去することができ、上述した操作を行うことにより、再度繰り返し記録が可能となる。 Further, the entire reversible multicolor recording medium 10 partially erased or developed as described above is uniformly heated at a temperature at which all the recording layers are colored, for example, 200 ° C. Then, the recording information and the image can be erased by cooling, and the recording can be repeated again by performing the operation described above.

本発明の可逆性多色記録媒体１０に対して、上記第１の原理、及び第２の原理に示した記録方法のうち、いずれの方法を適用するかは、記録層の特性、記録光源の性能に合わせて適宜選択する。
例えば、記録層を高温で発色してそれ以下の温度で消色する、いわゆるポジ型の層として形成してもよく、高温で消色してそれ以下の温度で発色する、いわゆるネガ型の層として形成してもよい（例えば特開平８−１９７８５３号公報）。 Which of the recording methods shown in the first principle and the second principle is applied to the reversible multicolor recording medium 10 of the present invention depends on the characteristics of the recording layer and the recording light source. Select appropriately according to the performance.
For example, the recording layer may be formed as a so-called positive type layer that develops color at a high temperature and erases at a temperature lower than that, or a so-called negative type layer that erases at a high temperature and develops color at a temperature below that. (For example, JP-A-8-197853).

次に、本発明の可逆性多色記録媒体について、具体的な実施例及び比較例を挙げて説明するが、本発明の可逆性多色記録媒体は以下に示す例に限定されるものではない。なお、以下に示す実施例５は参考例である。
Next, the reversible multicolor recording medium of the present invention will be described with specific examples and comparative examples. However, the reversible multicolor recording medium of the present invention is not limited to the following examples. . In addition, Example 5 shown below is a reference example.

〔実施例１〕
この例においては、支持基板１上に第１の記録層１１、断熱層１４、第２の記録層１２、断熱層１５、第３の記録層１３、及び保護層１６が順次積層された、いわゆる三層の記録層を有する可逆性多色記録媒体を作製する。 [Example 1]
In this example, the first recording layer 11, the heat insulating layer 14, the second recording layer 12, the heat insulating layer 15, the third recording layer 13, and the protective layer 16 are sequentially stacked on the support substrate 1. A reversible multicolor recording medium having three recording layers is produced.

支持基板１として、厚さ１ｍｍの白色のポリエチレンテレフタレート基板を使用した。第１の記録層１１としては、支持基板１上に下記組成物を含有する塗料をワイヤーバーで塗布し、１１０℃にて５分間加熱乾燥処理を施し、イエローに発色させることのできる記録層を膜厚５μｍに形成した。第１の記録層１１の波長９１５ｎｍの光における吸光度は１．０であった。 As the supporting substrate 1, a white polyethylene terephthalate substrate having a thickness of 1 mm was used. As the first recording layer 11, a recording layer that can be colored yellow by applying a coating containing the following composition on the support substrate 1 with a wire bar and subjecting it to a heat drying treatment at 110 ° C. for 5 minutes. The film thickness was 5 μm. The absorbance of the first recording layer 11 with light having a wavelength of 915 nm was 1.0.

（組成物）
ロイコ染料（フルオラン化合物：λmax＝４９０ｎｍ）：１重量部
顕・減色剤（下記化学式（４）に示す物質）：４重量部 (Composition)
Leuco dye (fluorane compound: λmax = 490 nm): 1 part by weight developer / color-reducing agent (substance shown in chemical formula (4) below): 4 parts by weight

増感剤（下記化学式（５）に示す物質）：０．２重量部
ＨＯ−Ｃ₁₈Ｈ₃₆−ＯＨ・・・（５）
塩化ビニル酢酸ビニル共重合体：１０重量部
（塩化ビニル９０％、酢酸ビニル１０％、平均分子量（Ｍ．Ｗ．）１１５０００）
シアニン系赤外吸収色素：０．１０重量部
（山本化成製、ＹＫＲ−２０８１、記録層中での吸収波長ピーク：９１０ｎｍ）
テトラヒドロフラン（ＴＨＦ）：１４０重量部 Sensitizer (substance shown in chemical formula (5) below): 0.2 part by weight HO—C ₁₈ H ₃₆ —OH (5)
Vinyl chloride vinyl acetate copolymer: 10 parts by weight (90% vinyl chloride, 10% vinyl acetate, average molecular weight (M.W.) 115000)
Cyanine-based infrared absorbing dye: 0.10 parts by weight (Yamamoto Kasei, YKR-2081, absorption wavelength peak in recording layer: 910 nm)
Tetrahydrofuran (THF): 140 parts by weight

上述のようにして形成した第１の記録層１１上に、ポリビニルアルコール水溶液を塗布、乾燥して膜厚２０μｍの断熱層１４を形成した。 On the first recording layer 11 formed as described above, an aqueous polyvinyl alcohol solution was applied and dried to form a heat insulating layer 14 having a thickness of 20 μm.

上記断熱層１４上に、第２の記録層１２として下記組成物を含有する塗料をワイヤーバーで塗布し、１１０℃にて５分間加熱乾燥処理を施し、シアンに発色させることのできる層を膜厚５μｍに形成した。第２の記録層１２の波長８３０ｎｍの光における吸光度は１．０であった。 On the heat insulation layer 14, a coating material containing the following composition is applied as a second recording layer 12 with a wire bar and subjected to a heat drying treatment at 110 ° C. for 5 minutes to form a layer capable of developing cyan. The thickness was 5 μm. The absorbance of the second recording layer 12 with light having a wavelength of 830 nm was 1.0.

（組成物）
ロイコ染料：１重量部
（山田化学工業製、Ｈ−３０３５（下記化学式（６）に示す物質） (Composition)
Leuco dye: 1 part by weight (manufactured by Yamada Chemical Co., Ltd., H-3035 (substance shown in the following chemical formula (6))

顕・減色剤（下記化学式（７）に示す物質）：４重量部 Developer / color-reducing agent (substance shown in chemical formula (7) below): 4 parts by weight

増感剤（下記化学式（８）に示す物質）：０．２重量部
ＨＯ−Ｃ₁₈Ｈ₃₆−ＯＨ・・・（８）
塩化ビニル酢酸ビニル共重合体：１０重量部
（塩化ビニル９０％、酢酸ビニル１０％、Ｍ．Ｗ．１１５０００）
シアニン系赤外吸収色素：０．０８重量部
（山本化成製、ＹＫＲ−２９００、記録層中での吸収波長ピーク８３０ｎｍ）
テトラヒドロフラン（ＴＨＦ）：１４０重量部 Sensitizer (substance shown in chemical formula (8) below): 0.2 part by weight HO—C ₁₈ H ₃₆ —OH (8)
Vinyl chloride vinyl acetate copolymer: 10 parts by weight (90% vinyl chloride, 10% vinyl acetate, MW 115000)
Cyanine-based infrared absorbing dye: 0.08 parts by weight (manufactured by Yamamoto Kasei, YKR-2900, absorption wavelength peak in recording layer 830 nm)
Tetrahydrofuran (THF): 140 parts by weight

上述のようにして形成した第２の記録層１２上に、ポリビニルアルコール水溶液を塗布、乾燥して膜厚２０μｍの断熱層１５を形成した。 On the second recording layer 12 formed as described above, a polyvinyl alcohol aqueous solution was applied and dried to form a heat insulating layer 15 having a thickness of 20 μm.

上記断熱層１５上に、第３の記録層１３として下記組成物を含有する塗料をワイヤーバーで塗布し、１１０℃にて５分間加熱乾燥処理を施し、マゼンダに発色させることのできる記録層を膜厚５μｍに形成した。第３の記録層１３の波長７８５ｎｍの光における吸光度は１．０であった。 A coating layer containing the following composition as a third recording layer 13 is applied to the heat insulating layer 15 with a wire bar, and subjected to a heat drying treatment at 110 ° C. for 5 minutes to form a recording layer capable of coloring magenta. The film thickness was 5 μm. The absorbance of the third recording layer 13 with light having a wavelength of 785 nm was 1.0.

（組成物）
ロイコ染料：２重量部
（保土ヶ谷化学社製、ＲｅｄＤＣＦ下記化学式（９）に示す物質） (Composition)
Leuco dye: 2 parts by weight (manufactured by Hodogaya Chemical Co., Ltd., Red DCF, a substance represented by the following chemical formula (9))

顕・減色剤（下記化学式（１０）に示す物質）：４重量部 Developer / color-reducing agent (substance shown in chemical formula (10) below): 4 parts by weight

増感剤（下記化学式（１１）に示す物質）：０．２重量部
ＨＯ−Ｃ₁₈Ｈ₃₆−ＯＨ・・・（１１）
塩化ビニル酢酸ビニル共重合体：１０重量部
（塩化ビニル９０％、酢酸ビニル１０％、Ｍ．Ｗ．１１５０００）
シアニン系赤外吸収色素：０．０８重量部
（日本化薬製、ＣＹ−１０、記録層中での吸収波長ピーク７９０ｎｍ）
テトラヒドロフラン（ＴＨＦ）：１４０重量部 Sensitizer (substance shown in chemical formula (11) below): 0.2 part by weight HO—C ₁₈ H ₃₆ —OH (11)
Vinyl chloride vinyl acetate copolymer: 10 parts by weight (90% vinyl chloride, 10% vinyl acetate, MW 115000)
Cyanine-based infrared absorbing dye: 0.08 parts by weight (manufactured by Nippon Kayaku, CY-10, absorption wavelength peak in recording layer 790 nm)
Tetrahydrofuran (THF): 140 parts by weight

上記第３の記録層１３上に、紫外線硬化性樹脂を用いて膜厚約２μｍの保護層１６を形成し、目的とする可逆性多色記録媒体１０を作製した。 A protective layer 16 having a film thickness of about 2 μm was formed on the third recording layer 13 using an ultraviolet curable resin, and the intended reversible multicolor recording medium 10 was produced.

第１〜第３の記録層１１〜１３中に含有されている化学式（４）、（７）、（１０）に示した顕・減色剤の合成方法について具体的な例を示す。
攪拌機を付けた５００ｍｌのフラスコ内に、5-Aminosalicylic acid：１５．３ｇ、n-Octadecyl isocyanateを２９．５ｇ、及びテトラヒドロフラン（ＴＨＦ）を２５０ｍｌ、それぞれ仕込み、９０℃で６時間還流した。
反応終了後、反応混合物を再結晶して目的物を得た。
収率は７５％で、目的物の融点は２１０℃であった。 A specific example of the method for synthesizing the developer / color-reducing agent shown in the chemical formulas (4), (7), and (10) contained in the first to third recording layers 11 to 13 will be described.
In a 500 ml flask equipped with a stirrer, 5-Aminosalicylic acid: 15.3 g, 29.5 g of n-Octadecyl isocyanate, and 250 ml of tetrahydrofuran (THF) were charged and refluxed at 90 ° C. for 6 hours.
After completion of the reaction, the reaction mixture was recrystallized to obtain the desired product.
The yield was 75%, and the melting point of the target product was 210 ° C.

上述のようにして作製した可逆性多色記録媒体１０を、１２０℃に加熱したセラミックスバーを用いて一様に加熱し、第１、第２及び第３の記録層１１、１２、１３を消色状態にしたものをサンプルとした。 The reversible multicolor recording medium 10 produced as described above is uniformly heated using a ceramic bar heated to 120 ° C., and the first, second and third recording layers 11, 12 and 13 are erased. A sample in a color state was used.

〔実施例２〕
上述した実施例１において適用した顕・減色剤を、下記化学式（１２）に示す化合物に変更した。その他の条件は実施例１と同様とし、サンプルを作製した。
下記化学式（１２）に示す化合物の合成方法は、上記化学式（４）、（７）、（１０）の顕・減色剤の合成方法における5-Aminosalicylic acidを、4-Aminosalicylic acidに変更した以外、他は同様とする。 [Example 2]
The developing / color-reducing agent applied in Example 1 described above was changed to a compound represented by the following chemical formula (12). Other conditions were the same as in Example 1, and a sample was prepared.
The synthesis method of the compound represented by the following chemical formula (12) is the same as the chemical formula (4), (7) and (10) except that 5-Aminosalicylic acid in the method of synthesizing the developer / color-reducing agent is changed to 4-Aminosalicylic acid. Others are the same.

〔実施例３〕
上述した実施例１において適用した顕・減色剤を、下記化学式（１３）に示す化合物に変更した。その他の条件は実施例１と同様としサンプルを作製した。
下記化学式（１３）に示す化合物の合成方法は、上記化学式（４）、（７）、（１０）の顕・減色剤の合成方法における5-Aminosalicylic acidを3-Aminosalicylic acidに変更した以外、他は同様とする。 Example 3
The developing / color-reducing agent applied in Example 1 described above was changed to a compound represented by the following chemical formula (13). Other conditions were the same as in Example 1, and a sample was prepared.
The synthesis method of the compound represented by the following chemical formula (13) may be other than changing the 5-Aminosalicylic acid to 3-Aminosalicylic acid in the method of synthesizing the developer / color-reducing agent of the above chemical formulas (4), (7) and (10). The same shall apply.

〔実施例４〕
上述した実施例１において適用した顕・減色剤を、下記化学式（１４）に示す化合物に変更した。その他の条件は実施例１と同様としサンプルを作製した。
下記化学式（１４）に示す化合物の合成方法は、上記化学式（４）、（７）、（１０）の顕・減色剤の合成方法における、5-Aminosalicylic acidを3-Hydroxy-4aminobenzoic acidに変更した以外、他は同様とする。 Example 4
The developing / color-reducing agent applied in Example 1 was changed to the compound represented by the following chemical formula (14). Other conditions were the same as in Example 1, and a sample was prepared.
The synthesis method of the compound represented by the following chemical formula (14) was changed from 5-Aminosalicylic acid to 3-Hydroxy-4aminobenzoic acid in the method of synthesizing the developer / color-reducing agent of the above chemical formulas (4), (7), and (10). Other than that, the same shall apply.

〔実施例５〕
上述した実施例１において増感剤を、下記化学式（１５）に示す化合物に変更した。その他の条件は実施例１と同様としサンプルを作製した。
ＨＯ−Ｃ₁₀Ｈ₂₀−ＯＨ・・・（１５） Example 5
In Example 1 described above, the sensitizer was changed to a compound represented by the following chemical formula (15). Other conditions were the same as in Example 1, and a sample was prepared.
_{_{HO-C 10 H 20 -OH ···}} (15)

〔実施例６〕
上述した実施例１において適用した増感剤を、下記化学式（１６）に示す化合物に変更した。その他の条件は実施例１と同様としサンプルを作製した。
ＨＯ−Ｃ₂₄Ｈ₄₈−ＯＨ・・・（１６） Example 6
The sensitizer applied in Example 1 described above was changed to a compound represented by the following chemical formula (16). Other conditions were the same as in Example 1, and a sample was prepared.
_{_{HO-C 24 H 48 -OH ···}} (16)

〔実施例７〕
実施例１において作製した可逆性多色記録媒体を、１８０℃に加熱したセラミックスバーを用いて加熱し、続いて冷却し、第１の記録層１１、第２の記録層１２、及び第３の記録層１３を、いずれも予め発色化させたものをサンプルとした。 Example 7
The reversible multicolor recording medium produced in Example 1 was heated using a ceramic bar heated to 180 ° C., then cooled, and the first recording layer 11, the second recording layer 12, and the third recording layer were cooled. The recording layer 13 was colored in advance as a sample.

〔比較例１〕
上述した実施例１において、増感剤を無添加とした。その他の条件は実施例１と同様としサンプルを作製した。 [Comparative Example 1]
In Example 1 described above, no sensitizer was added. Other conditions were the same as in Example 1, and a sample was prepared.

〔比較例２〕
上述した実施例１において適用した顕・減色剤を、下記化学式（１７）に示す化合物に変更した。その他の条件は実施例１と同様としサンプルを作製した。 [Comparative Example 2]
The developing / color-reducing agent applied in Example 1 described above was changed to a compound represented by the following chemical formula (17). Other conditions were the same as in Example 1, and a sample was prepared.

〔比較例３〕
上述した実施例１において適用した増感剤を、下記化学式（１８）に示す化合物に変更した。その他の条件は実施例１と同様としサンプルを作製した。
ＨＯ−Ｃ₅Ｈ₁₀−ＯＨ・・・（１８） [Comparative Example 3]
The sensitizer applied in Example 1 described above was changed to a compound represented by the following chemical formula (18). Other conditions were the same as in Example 1, and a sample was prepared.
_{_{HO-C 5 H 10 -OH ···}} (18)

〔比較例４〕
上述した実施例１において適用した増感剤を、下記化学式（１９）に示す化合物に変更した。その他の条件は実施例１と同様としサンプルを作製した。
ＨＯ−Ｃ₂₈Ｈ₅₆−ＯＨ・・・（１９） [Comparative Example 4]
The sensitizer applied in Example 1 described above was changed to a compound represented by the following chemical formula (19). Other conditions were the same as in Example 1, and a sample was prepared.
_{_{HO-C 28 H 56 -OH ···}} (19)

〔比較例５〕
上述した実施例１において適用した増感剤を、下記化学式（２０）に示す化合物に変更した。その他の条件は実施例１と同様としサンプルを作製した。
ＨＯ−Ｃ₁₈Ｈ₃₇・・・（２０） [Comparative Example 5]
The sensitizer applied in Example 1 described above was changed to a compound represented by the following chemical formula (20). Other conditions were the same as in Example 1, and a sample was prepared.
HO-C ₁₈ H ₃₇ (20)

上述のようにして作製した各記録媒体のサンプルについて、記録線幅、反射濃度、消去特性、及び記録層の透明性について評価を行った。
評価方法、及び評価結果について下記に示す。 Each sample of the recording medium produced as described above was evaluated for recording line width, reflection density, erasing characteristics, and transparency of the recording layer.
Evaluation methods and evaluation results are shown below.

（記録線幅測定）
サンプルの任意の位置に、波長７８５ｎｍ、８３０ｎｍ、９１５ｎｍ、出力７０ｍＷ、スポット径８０μｍの半導体レーザー光を、３００ｍｍ／ｓｅｃ速度でスキャンさせながら照射し、その記録線幅を測定した。 (Recording line width measurement)
An arbitrary position of the sample was irradiated with a semiconductor laser beam having a wavelength of 785 nm, 830 nm, 915 nm, an output of 70 mW, and a spot diameter of 80 μm while scanning at a speed of 300 mm / sec, and the recording line width was measured.

（反射濃度測定）
サンプルの任意の位置に、波長７８５ｎｍ、８３０ｎｍ、９１５ｎｍ、出力７０ｍＷ、スポット径８０μｍの半導体レーザー光を、スキャン速度３００ｍ／ｓの条件下、１０μｍ間隔で線を記録し、ベタ画像の記録を行った。
記録したサンプルについて、積分球を装着した自記分光光度計で反射率を測定し、ピーク波長での反射濃度を求めた。
なお、波長７８５ｎｍ、８３０ｎｍ、９１５ｎｍのレーザー光照射時のピーク波長は、それぞれ４９０ｎｍ、６６０ｎｍ、５３０ｎｍであった。 (Reflectance density measurement)
A solid image was recorded by recording a semiconductor laser beam having a wavelength of 785 nm, 830 nm, 915 nm, an output of 70 mW, and a spot diameter of 80 μm at an arbitrary position of the sample at a scanning speed of 300 m / s at intervals of 10 μm. .
The reflectance of the recorded sample was measured with a self-recording spectrophotometer equipped with an integrating sphere, and the reflection density at the peak wavelength was determined.
In addition, the peak wavelengths at the time of laser beam irradiation with wavelengths of 785 nm, 830 nm, and 915 nm were 490 nm, 660 nm, and 530 nm, respectively.

（消去特性評価：消去後の反射濃度測定）
サンプルの任意の位置に、波長７８５ｎｍ、８３０ｎｍ、９１５ｎｍ、出力７０ｍＷ、スポット径８０μｍの半導体レーザー光を、スキャン速度３００ｍｍ／ｓの条件下、１０μｍ間隔で線を記録し、ベタ画像の記録を行った。
その後サンプルに、波長７８５ｎｍ、８３０ｎｍ、９１５ｎｍ、出力７０ｍＷ、スポット径２５０μｍの半導体レーザー光を、２００ｍｍ／ｓｅｃの速度でスキャンさせながら照射し、記録部を消去した。
消去後のサンプルについて、積分球を装着した自記分光光度計で反射率を測定し、ピーク波長での反射濃度（反射率）を求めた。 (Erase characteristics evaluation: reflection density measurement after erasure)
A solid image was recorded by recording a semiconductor laser beam having a wavelength of 785 nm, 830 nm, 915 nm, an output of 70 mW, and a spot diameter of 80 μm at an arbitrary position of the sample at a scanning speed of 300 mm / s at an interval of 10 μm. .
Thereafter, the sample was irradiated with semiconductor laser light having a wavelength of 785 nm, 830 nm, 915 nm, an output of 70 mW, and a spot diameter of 250 μm while scanning at a speed of 200 mm / sec to erase the recording portion.
About the sample after erasure | elimination, the reflectance was measured with the self-recording spectrophotometer equipped with the integrating sphere, and the reflection density (reflectance) in a peak wavelength was calculated | required.

（記録層の透明性評価）
各記録層を単層膜厚４μｍで製膜し、目視にて透明性の良いものから、◎、○、△、×と４段階に評価した。 (Evaluation of recording layer transparency)
Each recording layer was formed with a single layer thickness of 4 μm, and was evaluated in four stages: ◎, ○, Δ, × from the one with good transparency.

（評価結果）
〔実施例１〜６〕、及び〔比較例１〜５〕の記録媒体について、出力７０ｍＷ、スポット径８０μｍ、波長９１５ｎｍ、８３０ｎｍ、７８５ｎｍのレーザー光を用いて、ベタ画像の記録を行い、記録線幅、得られたピーク波長での反射濃度、消去後の反射濃度の測定結果、及び記録層の透明性の評価結果を下記〔表１〕に示す。 (Evaluation results)
With respect to the recording media of [Examples 1 to 6] and [Comparative Examples 1 to 5], solid images were recorded using laser beams having an output of 70 mW, a spot diameter of 80 μm, wavelengths of 915 nm, 830 nm, and 785 nm, and recording lines Table 1 below shows the width, the obtained reflection density at the peak wavelength, the measurement result of the reflection density after erasure, and the evaluation result of the transparency of the recording layer.

表１に示すように、〔実施例１〜６〕の記録媒体においては、記録線幅は、〔比較例１、３〜５〕に比較して広く、優れた記録感度を有していることがわかった。
また、〔実施例１〜６〕の記録媒体は、ベタ画像の反射濃度も高く、照射光を高い効率で熱に変換し、記録層を発色させていることが分かった。
また、〔実施例１〜６〕の記録媒体を構成する記録層は、透明性評価が極めて良好であった。このことから、本発明の記録媒体を構成する記録層は、溶媒及びポリマーに対し、顕・減色剤、増感剤の溶解性が高く、かつ光−熱変換効率及び発色効率が高く、優れた記録感度を実現できたことがわかった。 As shown in Table 1, in the recording media of [Examples 1 to 6], the recording line width is wider than that of [Comparative Examples 1 and 3 to 5] and has excellent recording sensitivity. I understood.
In addition, it was found that the recording media of [Examples 1 to 6] had a high solid image reflection density, and converted the irradiation light into heat with high efficiency to develop the recording layer.
The recording layers constituting the recording media of [Examples 1 to 6] had very good transparency evaluation. From this, the recording layer constituting the recording medium of the present invention is excellent in the solubility of the developer / subtractor and the sensitizer in the solvent and the polymer, and in the light-heat conversion efficiency and the color development efficiency. It was found that the recording sensitivity could be realized.

また、例として〔実施例７〕の可逆性多色記録媒体をサンプルとし、これに対し、１８０℃に加熱したセラミックスバーを用いて加熱し、続いて冷却し、予め発色化させた状態とし、その後、波長９１５ｎｍ、８３０ｎｍ、７８５ｎｍそれぞれのレーザー光を照射し、記録部を消去したところ、鮮明な多色記録の画像を迅速に形成し、かつ消去できることが確かめられた。
また、多色画像は、記録層全体を予め消色化させた状態から記録形成した多色記録画像と同等の発色性、コントラスト、精細さを実現できることが確かめられた。 In addition, as an example, the reversible multicolor recording medium of [Example 7] is used as a sample. On the other hand, heating is performed using a ceramic bar heated to 180 ° C., followed by cooling to obtain a pre-colored state. Thereafter, laser beams of wavelengths 915 nm, 830 nm, and 785 nm were irradiated to erase the recording portion. As a result, it was confirmed that a clear multicolor recording image could be quickly formed and erased.
Further, it was confirmed that the multicolor image can realize color development, contrast, and fineness equivalent to those of the multicolor recording image formed by recording from the state in which the entire recording layer has been previously decolored.

〔実施例１〜６〕の記録媒体における消去後の反射濃度は、各波長ともに０．０３以下で、ほぼ無色状態であるのに対し、増感剤を適用しなかった〔比較例１〕の記録媒体においては、消去後の反射濃度が〔実施例１〜６〕に比較して高くなった。すなわち充分な消去効果が得られず、特に繰り返し記録を行う際において記録感度や視認性が低下した。 The reflection density after erasure in the recording media of [Examples 1 to 6] was 0.03 or less at each wavelength and was almost colorless, whereas no sensitizer was applied. In the recording medium, the reflection density after erasure was higher than those in [Examples 1 to 6]. That is, a sufficient erasing effect cannot be obtained, and the recording sensitivity and visibility are lowered particularly when performing repeated recording.

〔比較例２〕の記録媒体は、顕・減色剤の化学構造が本発明とは異なるものであり、アルキル鎖長が短く、分子間の凝集力が低下したため、消去特性が劣化し、消去後における反射濃度が高くなった。これにより、特に繰り返し記録を行う際において記録感度や視認性が低下した。 The recording medium of [Comparative Example 2] is different from the present invention in the chemical structure of the developer / color-reducing agent, the alkyl chain length is short, and the cohesive force between the molecules is reduced. The reflection density at was high. As a result, the recording sensitivity and the visibility are lowered particularly when performing repeated recording.

〔比較例３〕の記録媒体は、増感剤の化学構造が本発明とは異なるものであり、アルキル鎖長が短く、分子間の凝集力が低下したため、消去特性が劣化した。 In the recording medium of [Comparative Example 3], the chemical structure of the sensitizer is different from that of the present invention, the alkyl chain length is short, and the cohesive force between molecules is reduced, so that the erasing characteristics are deteriorated.

〔比較例４〕の記録媒体は、増感剤の化学構造が本発明とは異なるものであるため、ポリマー内での溶解性に劣り、分散白濁しており、透明性について実用上充分な評価が得られなかった。その結果、第３、第２、第１の記録層の順に、下層ほど記録線幅が狭くなり、記録感度の低下を招来した。これは、上層の未溶解の増感剤により、照射されたレーザー光が反射、散乱してしまい、光−熱変換の効率が低下したためである。 Since the recording medium of [Comparative Example 4] is different from the present invention in the chemical structure of the sensitizer, it is inferior in solubility in the polymer and is dispersed and cloudy, and the transparency is practically sufficiently evaluated. Was not obtained. As a result, in the order of the third, second, and first recording layers, the lower the recording line width, the lower the recording sensitivity. This is because the irradiated laser beam is reflected and scattered by the undissolved sensitizer in the upper layer, and the efficiency of light-heat conversion is lowered.

〔比較例５〕の記録媒体は、増感剤の化学構造が本発明とは異なるものであり、水酸基が一つであるため、充分な消去促進効果が得られず、消去後の反射濃度について実用上充分な評価が得られなかった。 The recording medium of [Comparative Example 5] is different from that of the present invention in the chemical structure of the sensitizer and has only one hydroxyl group, so that a sufficient erasure promoting effect cannot be obtained. A practically sufficient evaluation could not be obtained.

本発明の可逆性多色記録媒体の一例の概略断面図を示す。1 shows a schematic cross-sectional view of an example of a reversible multicolor recording medium of the present invention.

Explanation of symbols

１……支持基板、１０……可逆性多色記録媒体、１１……第１の記録層、１２……第２の記録層、１３……第３の記録層、１４，１５……断熱層、１６……保護層 DESCRIPTION OF SYMBOLS 1 ... Support substrate, 10 ... Reversible multicolor recording medium, 11 ... 1st recording layer, 12 ... 2nd recording layer, 13 ... 3rd recording layer, 14, 15 ... Heat insulation layer , 16 …… Protective layer

Claims

In the surface direction of the support substrate, a plurality of recording layers that reversibly develop different colors are separated and laminated, respectively.
The recording layer has at least a light-to-heat conversion material that generates heat by absorbing infrared rays in different wavelength ranges, a color-forming compound having electron donating properties, and an electron accepting property. ) A color developing / color-reducing agent comprising at least one compound represented by formula (2), a sensitizer comprising at least one compound represented by the following general formula (2), and a polymer comprising a vinyl chloride / vinyl acetate copolymer. Contained,
A reversible multicolor recording medium adapted to reversibly change the recording layer into two states of color development and decoloration by a reversible reaction between the color developing compound and the developer / color reducing agent. .

(However, R4 is a hydrocarbon group having 18 carbon atoms.)
HO-R3-OH (2)
(However, R3 is any hydrocarbon group having 18 or 24 carbon atoms.)

2. The reversible multicolor recording medium according to claim 1, wherein the plurality of recording layers are laminated and formed in a plane direction of the support substrate via heat insulating layers, respectively.

The reversible multicolor recording medium according to claim 1, wherein a protective layer is formed on the outermost surface.

In the surface direction of the support substrate, a plurality of recording layers that reversibly develop different colors are separated and laminated, respectively.
The recording layer has at least a light-to-heat conversion material that generates heat by absorbing infrared rays in different wavelength ranges, a color-forming compound having electron donating properties, and an electron accepting property. ) A color developing / color-reducing agent comprising at least one compound represented by formula (2), a sensitizer comprising at least one compound represented by the following general formula (2), and a polymer comprising a vinyl chloride / vinyl acetate copolymer. Contained,
A reversible multicolor recording medium adapted to reversibly change the recording layer into two states of color development and decoloration by a reversible reaction between the color developing compound and the developer / color reducing agent. Using,
Apply heat treatment to pre-decolor the entire recording layer,
In accordance with desired image information, exposure is performed by irradiating infrared rays of a wavelength region selected corresponding to the selected one of the recording layers,
A recording method for a reversible multicolor recording medium, wherein the image information is recorded by causing the recording layer to generate heat and selectively develop color.

In the surface direction of the support substrate, a plurality of recording layers that reversibly develop different colors are separated and laminated, respectively.
The recording layer has at least a light-to-heat conversion material that generates heat by absorbing infrared rays in different wavelength ranges, a color-forming compound having electron donating properties, and an electron accepting property. ) A color developing / color-reducing agent comprising at least one compound represented by formula (2), a sensitizer comprising at least one compound represented by the following general formula (2), and a polymer comprising a vinyl chloride / vinyl acetate copolymer. Contained,
A reversible multicolor recording medium adapted to reversibly change the recording layer into two states of color development and decoloration by a reversible reaction between the color developing compound and the developer / color reducing agent. Using,
Apply heat treatment to make the entire recording layer in a colored state in advance.
In accordance with desired image information, exposure is performed by irradiating infrared rays of a wavelength region selected corresponding to the selected one of the recording layers,
A recording method for a reversible multicolor recording medium, wherein the image information is recorded by causing the recording layer to generate heat and selectively decoloring.