JP4466226B2 - Reversible thermosensitive recording medium and recording method using the same - Google Patents
Reversible thermosensitive recording medium and recording method using the same Download PDFInfo
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Images
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- Heat Sensitive Colour Forming Recording (AREA)
Description
本発明は、所望の画像や各種データを記録する可逆性記録媒体、及びこれを用いた記録方法に関わる。 The present invention relates to a reversible recording medium for recording a desired image and various 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.
このような現状のもと、印刷物に替わる表示媒体の一例として、熱により情報の記録や消去が可能な記録媒体が、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用途においても実用化されつつある。 Under such circumstances, as an example of a display medium that replaces printed matter, a recording medium capable of recording and erasing information by heat has become a residual amount due to the spread of various prepaid cards, point cards, credit cards, IC cards, etc. And other recorded information, etc., are being put into practical use for visualization and readability, and are also being put into practical use for copying machines and printers.
上記のような記録媒体、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、ロイコ染料タイプ、すなわち樹脂母材中に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提案がなされており、これ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、視認性が良好であるという利点を有している。
Various proposals have heretofore been made regarding the recording medium as described above and a recording method using the same.
For example, a leuco dye type, that is, a recording medium having a recording layer in which a leuco dye which is a color developing compound in a resin base material and a developer / color-reducing agent are dispersed, and a recording method using the same are proposed. This has the advantage that contrast and visibility are better than those of the low molecular weight dispersion type because it utilizes the color of the leuco dye itself.
上記のような発色原理を応用し、ロイコ染料を用いた複数の記録層を分離、独立した状態で積層形成した構成の感熱記録媒体を用いて、レーザー光を照射し光−熱変換により任意の記録層のみを加熱せしめ、発色させる技術に関する開示がなされている（例えば、特許文献１参照。）。
この方法によれば、光−熱変換材料を含有している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るとされている。
Applying the color development principle as described above, separating a plurality of recording layers using leuco dyes, using a heat-sensitive recording medium having a structure in which layers are formed in an independent state, irradiating a laser beam and performing arbitrary conversion by light-to-heat conversion There is a disclosure relating to a technique for heating only the recording layer to develop a color (for example, see Patent Document 1).
According to this method, only an arbitrary recording layer can be colored by the effect of wavelength selectivity of the layer containing the light-heat conversion material.
しかしながら、上記特許文献１に開示されている技術においては、光−熱変換層（レーザー光の吸収層）を、バインダーを含有させず、有機溶剤に溶解した光吸収材料を被着させることにより形成することを好適であるとしているが、このような光−熱変換層は、極めて広い波長領域においてレーザー光の吸収を有するようになってしまい、表示精度が劣化するという欠点を有している。 However, in the technique disclosed in Patent Document 1, the light-to-heat conversion layer (laser light absorption layer) is formed by adhering a light absorbing material dissolved in an organic solvent without containing a binder. However, such a light-heat conversion layer has a drawback that the display accuracy is deteriorated because it absorbs laser light in an extremely wide wavelength region.
また、かかる方法において成膜されたレーザー光の吸収層は、可視域においても光吸収を有することとなり、消去状態において記録層の透明性が劣化し、記録精度の悪化を招来するという問題も有している。 In addition, the laser light absorption layer formed by such a method has light absorption even in the visible range, and there is a problem that the transparency of the recording layer deteriorates in the erased state, leading to deterioration in recording accuracy. is doing.
このような問題を解決した可逆性記録媒体を得るためには、光−熱変換材料に関し、最適な光吸収特性を選定するべく、厳密に化学構造を制御したり、記録レーザー光の波長を厳密に選択したりしなければならなくなる。 In order to obtain a reversible recording medium that solves these problems, the chemical structure is strictly controlled and the wavelength of the recording laser light is strictly controlled in order to select the optimum light absorption characteristics for the light-to-heat conversion material. You will have to choose.
しかしながら、上記問題に対応するべく最適化した光−熱変換材料は、必然的に化学構造が限定されてしまうため、適用できる光−熱変換材料の種類が非常に限られてしまい、また、合成プロセスも複雑化するという問題が生じる。 However, the light-to-heat conversion material optimized to deal with the above problem inevitably has a limited chemical structure, so the types of light-to-heat conversion material that can be applied are very limited, and synthesis is also possible. The problem is that the process is also complicated.
また、従来公知の可逆性感熱記録媒体は、一般的に光に対する耐久性についての検討が不充分であり、特に記録用の発色材料と混合すると、経時的に分解することにより徐々に機能が低下していき、多数回繰り返して記録と消去とを行うと、発・消色性が著しく劣化するという実用上の課題を有している。
これは、光−熱変換材料、及び感熱発色性組成物が、外部から侵入した酸素と光により生成される活性酸素によって化学的に分解されてしまうことに起因している。
よって、今後、記録媒体の高密度記録化や小型薄層化が進められていくことを考慮しても、外部からの酸素の侵入を意図的に防止した構成を有する可逆性記録媒体の開発が望まれていた。
In addition, conventionally known reversible thermosensitive recording media generally have insufficient studies on durability against light, and when mixed with a coloring material for recording, the function gradually deteriorates due to decomposition over time. However, when recording and erasing are repeated many times, there is a practical problem that the color development / decoloring property is remarkably deteriorated.
This is due to the fact that the light-heat conversion material and the heat-sensitive color-developing composition are chemically decomposed by oxygen that has entered from the outside and active oxygen generated by light.
Therefore, even in consideration of the future progress of high-density recording and miniaturization and thinning of recording media, the development of a reversible recording medium having a configuration that intentionally prevents oxygen from entering from the outside has been developed. It was desired.
そこで本発明においては、上述したような従来技術の問題に鑑みて、化学構造上の制約が少なく、多くの光−熱変換材料が適用可能で、かつ発色性が良好でコントラストに優れ、色かぶりが無く、実用上問題のない画像安定性を持ち、優れた耐光性を有し、外部からの酸素の侵入に対して優れたバリア性を有し、長期に亘って優れた発色再現性を維持可能とした可逆性記録媒体、及びこれを用いた記録方法を提供することとした。 Therefore, in the present invention, in view of the problems of the prior art as described above, there are few restrictions on the chemical structure, many light-to-heat conversion materials can be applied, good color development, excellent contrast, and color cast. No image problems, practical image stability, excellent light resistance, excellent barrier against intrusion of oxygen from the outside, and excellent color reproducibility over a long period of time It was decided to provide a reversible recording medium made possible and a recording method using the same.
本発明においては、支持基板の面方向に、特定の波長領域の近赤外線を吸収して発熱する光−熱変換材料と、温度変化に応じて、無色・着色の二状態を可逆的に変化する感熱発色性組成物とが、樹脂中に含有されている可逆性感熱記録層と、外部から前記可逆性感熱記録層への酸素侵入を防ぐ酸素ガスバリア性を有する酸素ガスバリア層とを備え、前記可逆性感熱記録層は、前記光−熱変換材料を含有する光−熱変換層と、前記感熱発色性組成物が樹脂中に含有されている記録層と、酸素ガスバリア性を有する中間層と、を有し、前記光−熱変換層と前記記録層とが、前記中間層を介して積層されてなり、前記酸素ガスバリア層は、膜厚０．１〜２０μｍであり、前記中間層は、膜厚０．１〜１０μｍであり、前記支持基板上の積層順を基準として、前記可逆性感熱記録層の、上層側と下層側に前記酸素ガスバリア層が設けられてなり、当該酸素ガスバリア層により、前記可逆性感熱記録層が挟み込まれてなる構成を有している可逆性感熱記録媒体を提供する。
In the present invention, in the surface direction of the support substrate, the light-to-heat conversion material that generates heat by absorbing near infrared rays in a specific wavelength region, and two states of colorless and colored are reversibly changed according to the temperature change. The thermosensitive coloring composition comprises a reversible thermosensitive recording layer contained in a resin, and an oxygen gas barrier layer having an oxygen gas barrier property that prevents oxygen from entering the reversible thermosensitive recording layer from the outside. The heat-sensitive recording layer comprises a light-heat conversion layer containing the light-heat conversion material, a recording layer containing the heat-sensitive color-forming composition in a resin, and an intermediate layer having oxygen gas barrier properties. The light-to-heat conversion layer and the recording layer are laminated via the intermediate layer, the oxygen gas barrier layer has a thickness of 0.1 to 20 μm, and the intermediate layer has a thickness of Ri 0.1~10μm der, and based on the order of stacking on the support substrate The oxygen gas barrier layer is provided on the upper layer side and the lower layer side of the reversible thermosensitive recording layer, and the reversible thermosensitive recording layer is sandwiched between the oxygen gas barrier layers. A reversible thermosensitive recording medium is provided.
本発明の記録方法は、支持基板の面方向に、特定の波長領域の近赤外線を吸収して発熱する光−熱変換材料と、温度変化に応じて、無色・着色の二状態を可逆的に変化する感熱発色性組成物とが、樹脂中に含有されている可逆性感熱記録層と、外部から可逆性感熱記録層への酸素侵入を防ぐ酸素ガスバリア性を有する酸素ガスバリア層とを備え前記可逆性感熱記録層は、前記光−熱変換材料を含有する光−熱変換層と、前記感熱発色性組成物が樹脂中に含有されている記録層と、酸素ガスバリア性を有する中間層と、を有し、前記光−熱変換層と前記記録層とが、前記中間層を介して積層されてなり、前記酸素ガスバリア層は、膜厚０．１〜２０μｍであり、前記中間層は、膜厚０．１〜１０μｍであり、前記支持基板上の積層順を基準として、前記可逆性感熱記録層の、上層側と下層側に前記酸素ガスバリア層が設けられてなり、当該酸素ガスバリア層により、前記可逆性感熱記録層が挟み込まれてなる構成を有している可逆性感熱記録媒体を用いて、任意に選択された波長の近赤外線を照射することによって、記録または消去を行うものとする。
In the recording method of the present invention, a light-to-heat conversion material that generates heat by absorbing near-infrared rays in a specific wavelength region in a surface direction of a support substrate, and two states of colorless and colored are reversibly changed according to a temperature change. The reversible thermochromic composition comprises a reversible thermosensitive recording layer contained in a resin and an oxygen gas barrier layer having an oxygen gas barrier property that prevents oxygen from entering the reversible thermosensitive recording layer from the outside. The heat-sensitive recording layer comprises a light-heat conversion layer containing the light-heat conversion material, a recording layer containing the heat-sensitive color-forming composition in a resin, and an intermediate layer having oxygen gas barrier properties. The light-to-heat conversion layer and the recording layer are laminated via the intermediate layer, the oxygen gas barrier layer has a thickness of 0.1 to 20 μm, and the intermediate layer has a thickness of Ri 0.1~10μm der, based on the order of stacking on the support substrate The reversible heat-sensitive recording layer is provided with the oxygen gas barrier layer on the upper layer side and the lower layer side, and the reversible heat-sensitive recording layer is sandwiched by the oxygen gas barrier layer . Recording or erasing is performed by irradiating near infrared rays having an arbitrarily selected wavelength using a thermal recording medium.
酸素ガスバリア層を設け、外部からの酸素の侵入を抑制したことにより、可逆性感熱記録層における活性酸素の発生が防止でき、光−熱変換材料、及び感熱発色性組成物の化学変化や経時的な機能の劣化が回避され、繰り返して発・消色の変換を行った場合においても、長期に亘って初期と同等の記録画質が維持できた。 By providing an oxygen gas barrier layer and suppressing the ingress of oxygen from the outside, the generation of active oxygen in the reversible thermosensitive recording layer can be prevented, and the chemical change and time-lapse of the light-to-heat conversion material and the thermosensitive coloring composition can be prevented. Therefore, even when repeated conversion between color generation and decoloration was performed, the recording image quality equivalent to the initial value could be maintained for a long time.
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、本発明は、以下に示す例に限定されるものではない。
なお、以下においては、三層の可逆性感熱記録層が形成されている構成の可逆性感熱記録媒体を例に挙げて説明するが、本発明はこの例に限定されるものではなく、例えば単色や二色のみ発色可能なものでもよく、一以上の可逆性感熱記録層が形成されている構成のものであれば、いずれも適用可能である。
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the examples shown below.
In the following, a reversible thermosensitive recording medium having a structure in which three reversible thermosensitive recording layers are formed will be described as an example. However, the present invention is not limited to this example. Alternatively, any one capable of developing only two colors may be used as long as one or more reversible thermosensitive recording layers are formed.
図１に本発明の一例としての可逆性感熱記録媒体の概略断面図を示す。
この可逆性感熱記録媒体１０は、支持基板１の面方向に、第１〜第３の光−熱変換層１１〜１３が中間層１４〜１６を介して第１〜第３の記録層１７〜１９と積層された構成の第１〜第３の可逆性感熱記録層３１〜３３が、酸素ガスバリア層２１、２１によって挟まれてなる構成を有している。
また、第１〜第３の可逆性感熱記録層３１〜３３の、それぞれの層間には、断熱層２３、２４が介在されてなり、最上層に保護層２５が形成されている。
以下、各層について詳細に説明する。
FIG. 1 is a schematic sectional view of a reversible thermosensitive recording medium as an example of the present invention.
In the reversible thermosensitive recording medium 10, first to third light-heat conversion layers 11 to 13 are arranged in the surface direction of the support substrate 1 through intermediate layers 14 to 16 to first to third recording layers 17 to 17. 19, the first to third reversible thermosensitive recording layers 31 to 33 having a configuration laminated with the oxygen gas barrier layers 21 and 21 are included.
Further, heat insulating layers 23 and 24 are interposed between the first to third reversible thermosensitive recording layers 31 to 33, and a protective layer 25 is formed as the uppermost layer.
Hereinafter, each layer will be described in detail.
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。
なお、支持基板１に、酸素ガス透過性の低い材料を選定することにより、支持基板１側からの酸素ガスの侵入を効果的に抑制できるようになる。
また、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記録媒体１０に対して記録を行った際の視認性の向上を図るため、白色、あるいは金属色等の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.
In addition, by selecting a material having low oxygen gas permeability for the support substrate 1, it is possible to effectively suppress the invasion of oxygen gas from the support substrate 1 side.
In addition, for the purpose other than the transmission use such as an overhead projector, the support substrate 1 is visible in white or metal color in order to improve the visibility when recording is performed on the finally obtained reversible recording medium 10. It is preferable to form with a material having high reflectance to light.
第１〜第３の光−熱変換層１１〜１３は、それぞれ異なる波長域の光を吸収して発熱する光−熱変換材料、樹脂ポリマー、及び各種添加剤とからなる光−熱変換組成物により構成されているものとする。 The first to third light-to-heat conversion layers 11 to 13 each comprise a light-to-heat conversion composition comprising a light-to-heat conversion material, a resin polymer, and various additives that generate heat by absorbing light in different wavelength ranges. It shall be comprised by.
光−熱変換材料は、消去状態における発色を回避し、かつ色かぶりを防止して記録感度を向上させるため、可視波長域にほとんど吸収がなく、吸収帯の幅が狭い色素を主成分として適用するものとし、また、所定の溶剤を用いて樹脂バインダーに均一に溶解させた状態で適用するものとする。 Light-to-heat conversion material avoids color development in the erased state and prevents color fogging to improve recording sensitivity. Therefore, it uses dyes that have almost no absorption in the visible wavelength range and a narrow absorption band as the main component. It shall be applied in a state where it is uniformly dissolved in a resin binder using a predetermined solvent.
上記のような光−熱変換材料としては、可視波長域に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使用でき、中でもシアニン系色素が好適である。
シアニン色素は、可視域の吸収が少なく、近赤外域に鋭い吸収を持っている。構造により吸収極大波長が変化するので、記録に用いるレーザー波長に適したものを選択することができる。
As the light-to-heat conversion material as described above, phthalocyanine dyes, cyanine dyes, metal complex dyes, diimmonium dyes, etc., which are generally used as infrared absorbing dyes having no absorption in the visible wavelength range, can be used. Cyanine dyes are preferred.
Cyanine dyes have little absorption in the visible range and sharp absorption in the near infrared range. Since the absorption maximum wavelength varies depending on the structure, it is possible to select one suitable for the laser wavelength used for recording.
上記光−熱変換材料を分散させる樹脂バインダーとしては、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、マレイン酸系共重合体、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、ゼラチン、デンプン等や、紫外線硬化性樹脂や熱硬化性樹脂等が挙げられる。
特に、酸素ガス透過率の低い材料を選定することにより、光−熱変換材料の活性酸素による劣化を効果的に回避することができる。
Examples of the resin binder in which the light-to-heat conversion material is dispersed include, for example, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethyl cellulose, polystyrene, styrene copolymer, phenoxy resin, polyester, and aromatic. Polyester, polyurethane, polycarbonate, polymethacrylate, acrylic acid copolymer, maleic acid copolymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, gelatin, starch, etc., UV curable resin and heat Examples thereof include curable resins.
In particular, by selecting a material having a low oxygen gas permeability, degradation of the light-heat conversion material due to active oxygen can be effectively avoided.
また、光−熱変換層１１〜１３には、必要に応じて紫外線吸収剤、一重項酸素失活剤等の各種添加剤を添加してもよい。
一重項酸素失活剤は、共役ポリエン、遷移金属錯体、ヒンダードアミン、アミン類、アミニウム塩、及びイミニウム塩からなる群より選ばれる少なくとも一種を含有するものとする。
これらの一重項酸素失活剤の添加量は、光−熱変換層を構成する光−熱変換材料に対して、重量比で０．０５倍〜４倍程度とすることが好ましく、さらに０．１倍〜２倍とすることがより好ましい。
Moreover, you may add various additives, such as a ultraviolet absorber and a singlet oxygen quencher, to the light-heat conversion layers 11-13 as needed.
The singlet oxygen quencher contains at least one selected from the group consisting of conjugated polyenes, transition metal complexes, hindered amines, amines, aminium salts, and iminium salts.
The addition amount of these singlet oxygen quenching agents is preferably about 0.05 to 4 times by weight with respect to the light-to-heat conversion material constituting the light-to-heat conversion layer. More preferably, it is 1 to 2 times.
第１〜第３の光−熱変換層１１〜１３の膜厚は、０．０５〜１０μｍ程度が好ましく、更に好ましくは０．１〜５μｍ程度であるものとする。これらの膜厚が厚すぎると充分な発色濃度が得られず、逆に薄過ぎると光−熱変換材料である色素が充分に溶解しきれなくなるためである。 The film thicknesses of the first to third light-heat conversion layers 11 to 13 are preferably about 0.05 to 10 μm, and more preferably about 0.1 to 5 μm. If these film thicknesses are too thick, a sufficient color density cannot be obtained. Conversely, if the film thickness is too thin, the dye as the light-heat conversion material cannot be sufficiently dissolved.
第１〜第３の中間層１４〜１６は、従来公知の光透過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、マレイン酸系共重合体、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、ゼラチン、デンプン等を適用でき、また、紫外線硬化性樹脂や熱硬化性樹脂を用いて形成してもよい。
なお、第１〜第３の中間層１４〜１６形成用材料としては、酸素ガス透過率の低い材料を選定することが好ましく、例えば、ポリビニルアルコールを適用すると、酸素ガスの透過性を極めて低く抑制することができ、活性酸素の発生による光−熱変換材料の劣化を効果的に回避することができる。
また、第１〜第３の中間層１４〜１６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 first to third intermediate layers 14 to 16 can be formed using a conventionally known light-transmitting polymer.
For example, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethyl cellulose, polystyrene, styrene copolymer, phenoxy resin, polyester, aromatic polyester, polyurethane, polycarbonate, polymethacrylate, acrylic acid Copolymers, maleic acid-based copolymers, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, gelatin, starch, etc. can be applied, and they can be formed using ultraviolet curable resins or thermosetting resins. Good.
In addition, as a material for forming the first to third intermediate layers 14 to 16, it is preferable to select a material having a low oxygen gas permeability. For example, when polyvinyl alcohol is applied, oxygen gas permeability is suppressed to be extremely low. It is possible to effectively avoid deterioration of the light-to-heat conversion material due to generation of active oxygen.
Moreover, you may use together various additives, such as a ultraviolet absorber, for the 1st-3rd intermediate | middle layers 14-16 as needed.
中間層１４〜１６は、透光性の無機膜を適用して形成してもよい。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適用すると熱伝導率の低減化が図られ好ましい。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。 The intermediate layers 14 to 16 may be formed by applying a light-transmitting inorganic film. For example, it is preferable to apply porous silica, alumina, titania, carbon, or a composite thereof to reduce thermal conductivity. These can be formed by a sol-gel method that can form a film from a liquid layer.
なお、中間層１４〜１６を構成する樹脂に関しては、隣接する光−熱変換層１１〜１３や記録層１７〜１９を構成する樹脂と、互いに相溶しないように選定するものとし、これにより、互いに分離・独立した状態で存在させるようにすることが望ましい。
中間層１４〜１６は、膜厚０．０５〜３０μｍ程度とすることが好ましく、更に好ましくは０．１〜１０μｍ程度とする。これらの膜厚が薄すぎると光−熱変換材料の劣化が著しくなり、逆に厚過ぎると熱伝導性が劣化するため充分な発色濃度が得られないためである。
The resin constituting the intermediate layers 14 to 16 is selected so as not to be mutually compatible with the resin constituting the adjacent light-heat conversion layers 11 to 13 and the recording layers 17 to 19. It is desirable to exist in a state of being separated and independent from each other.
The intermediate layers 14 to 16 preferably have a thickness of about 0.05 to 30 μm, more preferably about 0.1 to 10 μm. If the film thickness is too thin, the light-to-heat conversion material is significantly deteriorated. On the other hand, if the film is too thick, the heat conductivity is deteriorated, so that a sufficient color density cannot be obtained.
次に、第１〜第３の記録層１７〜１９について説明する。
第１〜第３の記録層１７〜１９は、熱状態を制御することによって安定した発・消色状態（着色状態と透明状態）とを形成し得る材料により形成するものとし、これにより繰り返して記録と消去を可能としたものとする。
Next, the first to third recording layers 17 to 19 will be described.
The first to third recording layers 17 to 19 are formed of a material capable of forming a stable color generation / decoloring state (colored state and transparent state) by controlling the heat state, and this is repeated. It shall be possible to record and erase.
第１〜第３の記録層１７〜１９は、少なくとも、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・減色剤よりなる感熱発色性組成物とが、所定の溶剤を用いて樹脂バインダーに均一に溶解された状態で形成されているものとする。 Each of the first to third recording layers 17 to 19 includes at least a color developing compound having an electron donating property, such as a leuco dye, and a thermosensitive coloring composition comprising a developer / color-reducing agent having a predetermined electron accepting property. Suppose that it is formed in a state of being uniformly dissolved in a resin binder using a predetermined solvent.
第１〜第３の記録層１７〜１９は、呈色性化合物としてロイコ染料を用いる場合、それぞれの記録層において発色させる所望の色に応じた材料を適用するものとし、例えば第１〜第３の記録層１７〜１９において、三原色を発するようにすれば、この可逆性記録媒体１０全体としてフルカラー画像の形成が可能になる。なお、ロイコ染料としては、既存の感熱紙用染料等を適用することができる。
上記顕・減色剤としては、従来これらに用いられている長鎖アルキル基を有する有機酸（特開平５−１２４３６０号公報、特開平７−１０８７６１号公報、特開平７−１８８２９４号公報、特開２００１−１０５７３３号公報、特開２００１−１１３８２９号公報等に記載）を適用することができる。
For the first to third recording layers 17 to 19, when a leuco dye is used as the color developing compound, a material corresponding to a desired color to be developed in each recording layer is applied, for example, the first to third recording layers. If the recording layers 17 to 19 emit the three primary colors, the entire reversible recording medium 10 can form a full-color image. As the leuco dye, an existing thermal paper dye or the like can be applied.
As the developer / color-reducing agent, organic acids having a long-chain alkyl group conventionally used in these (JP-A-5-124360, JP-A-7-108761, JP-A-7-188294, JP-A-7-238294 2001-105733, JP-A-2001-113829, etc.) can be applied.
第１〜第３の記録層１７〜１９を形成する樹脂バインダーとしては、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、セルロース変性体、アセタール樹脂、ブチラール樹脂、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、ポリエーテル樹脂、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。
なお、第１〜第３の記録層１７〜１９形成用樹脂バインダーとしては、酸素ガスの透過性を極めて低い材料を選定することが好ましい。これにより、活性酸素の発生による、呈色性化合物の劣化を効果的に防止することができる。
Examples of the resin binder for forming the first to third recording layers 17 to 19 include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, modified cellulose, acetal resin, butyral resin, polystyrene, and styrene. Copolymer, phenoxy resin, polyester, aromatic polyester, polyether resin, polyurethane, polycarbonate, polyacrylate ester, polymethacrylate ester, acrylic acid copolymer, maleic acid polymer, polyvinyl alcohol, modified polyvinyl Examples include alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, starch and the like.
As the resin binder for forming the first to third recording layers 17 to 19, it is preferable to select a material having extremely low oxygen gas permeability. Thereby, deterioration of the color developing compound due to generation of active oxygen can be effectively prevented.
第１〜第３の記録層１７〜１９は、上記ロイコ染料、顕・減色剤、及び各種添加剤を、溶媒を用いて上記樹脂バインダー中に溶解あるいは分散させて塗料を作製し、これを所定の形成面に塗布することによって成膜することができる。
第１〜第３の記録層１７〜１９は、膜厚１〜５０μｍ程度に形成することが望ましく、さらには２〜２０μｍ程度の膜厚とすることが好ましい。これらの膜厚が薄すぎると充分な発色濃度が得られず、逆に厚過ぎると層の熱容量が大きくなりすぎ、発色性や消色性が劣化したり、あるいは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 first to third recording layers 17 to 19 are prepared by dissolving or dispersing the leuco dye, the developing / color-reducing agent, and various additives in the resin binder using a solvent. It can form into a film by apply | coating to the formation surface.
The first to third recording layers 17 to 19 are preferably formed to a thickness of about 1 to 50 μm, and more preferably about 2 to 20 μm. If these film thicknesses are too thin, a sufficient color density cannot be obtained. Conversely, if the film thickness is too thick, the heat capacity of the layer becomes too large, and the color development and decoloring properties deteriorate, or the thermal conductivity deteriorates. This is because the translucency is lowered.
次に、酸素ガスバリア層２１、２２について説明する。
酸素ガスバリア層２１、２２は、外部からの、可逆性感熱記録層３１〜３３への酸素侵入を防ぐ機能を有しているものとする。
よって、可逆性感熱記録媒体１０において、少なくとも一層以上形成することが必要であり、特に、光−熱変換層１１〜１３に外部から酸素が侵入することを効果的に防止するように、図１に示すように、可逆性感熱記録層３１〜３３の支持基板１側と保護層２５側の双方から、すなわち上層と下層の双方から挟み込む構成とすることが好ましい。
Next, the oxygen gas barrier layers 21 and 22 will be described.
The oxygen gas barrier layers 21 and 22 have a function of preventing oxygen from entering the reversible thermosensitive recording layers 31 to 33 from the outside.
Therefore, it is necessary to form at least one layer in the reversible thermosensitive recording medium 10, and in particular, in order to effectively prevent oxygen from entering the light-heat conversion layers 11 to 13 from the outside. As shown in FIG. 4, it is preferable to sandwich the reversible thermosensitive recording layers 31 to 33 from both the support substrate 1 side and the protective layer 25 side, that is, from both the upper layer and the lower layer.
酸素ガスバリア層２１、２２の酸素ガスバリア機能は、例えば、膜厚２０μｍのサンプルを用い、２０℃、６０％ＲＨの条件下において、酸素ガス透過度が、２０ｍｌ／ｍ２.２４Ｈｒｓ・ａｔｍ以下に選定することが望ましい。
このような優れた酸素ガスバリア性を有する樹脂としては、例えば、エチレン−ビニルアルコール共重合体（０．２ｍｌ／ｍ２.２４Ｈｒｓ・ａｔｍ）、ポリビニルアルコール（０．２ｍｌ／ｍ２.２４Ｈｒｓ・ａｔｍ）、変性ポリビニルアルコール（０．２ｍｌ／ｍ２.２４Ｈｒｓ・ａｔｍ）、ポリ塩化ビニリデン（３ｍｌ／ｍ２.２４Ｈｒｓ・ａｔｍ）、ポリアクリロニトリル（１５ｍｌ／ｍ２.２４Ｈｒｓ・ａｔｍ）等が好適な材料として挙げられる。
Oxygen gas barrier function of the oxygen gas barrier layer 21 and 22, for example, using a sample having a thickness of 20 [mu] m, 20 ° C., under the conditions of RH 60%, the oxygen gas permeability, selected below 20ml / m 2 .24Hrs · atm It is desirable to do.
Such excellent oxygen gas barrier resin having, for example, ethylene - vinyl alcohol copolymer (0.2ml / m 2 .24Hrs · atm ) , polyvinyl alcohol (0.2ml / m 2 .24Hrs · atm ) , modified polyvinyl alcohol (0.2ml / m 2 .24Hrs · atm ), polyvinylidene chloride (3ml / m 2 .24Hrs · atm ), polyacrylonitrile (15ml / m 2 .24Hrs · atm ) or the like is mentioned as a suitable material It is done.
また、ポリエステル、ポリアミドについては、薄膜にすると酸素ガス透過率が上記数値よりも高くなるが、支持基板１として適用する場合においては、充分な酸素ガスバリア機能を発揮し得る。 Further, when the polyester and polyamide are made into a thin film, the oxygen gas permeability becomes higher than the above numerical value, but when applied as the support substrate 1, a sufficient oxygen gas barrier function can be exhibited.
酸素ガスバリア層２１、２２は、多孔質のシリカ、アルミナ、チタニア、カーボン、マイカ、クレイ、カオリン、炭酸カルシウム等の、無機物を配合した樹脂フィルムを用いてもよい。
また、酸素ガスバリア層２１、２２は、透光性の無機材料を蒸着により成膜したものとしてもよい。透光性の無機材料としては、例えば、シリカ、アルミナ等が挙げられる。蒸着する方法としては、ＰＶＤ法やＣＶＤ法が好適である。
なお、酸素ガスバリア層２１、２２には、必要に応じて一重項酸素失活剤や紫外線吸収剤等の各種添加剤を併用してもよい。
The oxygen gas barrier layers 21 and 22 may be made of a resin film containing an inorganic substance such as porous silica, alumina, titania, carbon, mica, clay, kaolin, calcium carbonate, or the like.
The oxygen gas barrier layers 21 and 22 may be formed by depositing a light-transmitting inorganic material by vapor deposition. Examples of the light-transmitting inorganic material include silica and alumina. As a vapor deposition method, a PVD method or a CVD method is suitable.
In addition, you may use together various additives, such as a singlet oxygen quencher and a ultraviolet absorber, for the oxygen gas barrier layers 21 and 22 as needed.
酸素ガスバリア層２１、２２は、膜厚０．０１〜５０μｍ程度に形成することが望ましく、さらには０．１〜２０μｍ程度の膜厚とすることが好ましい。これらの膜厚が薄すぎると充分な酸素ガスバリア性が得られず、逆に厚過ぎると熱伝導性が劣化するためである。 The oxygen gas barrier layers 21 and 22 are preferably formed to a thickness of about 0.01 to 50 μm, and more preferably about 0.1 to 20 μm. This is because if these film thicknesses are too thin, sufficient oxygen gas barrier properties cannot be obtained, and conversely if they are too thick, thermal conductivity deteriorates.
可逆性感熱記録層３１と、可逆性感熱記録層３２との間、及び可逆性感熱記録層３２と可逆性感熱記録層３３との間には、照射する近赤外光に対して透光性の断熱層２３、２４を形成することが望ましい。
これによって、記録時において隣接するリライタブル層の熱が伝導してしまうことが回避され、いわゆる色かぶりの発生を防止する効果が得られる。
Between the reversible thermosensitive recording layer 31 and the reversible thermosensitive recording layer 32, and between the reversible thermosensitive recording layer 32 and the reversible thermosensitive recording layer 33, it is translucent to the near infrared light to be irradiated. It is desirable to form the heat insulating layers 23 and 24.
This avoids conduction of heat between adjacent rewritable layers during recording, and an effect of preventing the occurrence of so-called color fogging can be obtained.
断熱層２３、２４は、従来公知の透光性の樹脂材料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。
また、上記材料のうち、酸素ガスの透過性を極めて低い材料を選定することが好ましい。これにより、活性酸素の発生による、呈色性化合物の劣化を効果的に防止することができる。
断熱層２３、２４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。
また、断熱層２３、２４は、透光性の無機膜を適用してもよい。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適用すると熱伝導率の低減化が図られ好ましい。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。
The heat insulation layers 23 and 24 can be formed using a conventionally known translucent resin material. For example, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethyl cellulose, polystyrene, styrene copolymer, phenoxy resin, polyester, aromatic polyester, polyurethane, polycarbonate, polyacrylate ester, polymethacrylate ester , Acrylic acid copolymer, maleic acid polymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, starch and the like.
Of the above materials, it is preferable to select a material with extremely low oxygen gas permeability. Thereby, deterioration of the color developing compound due to generation of active oxygen can be effectively prevented.
Various additives such as an ultraviolet absorber may be used in combination in the heat insulating layers 23 and 24 as necessary.
Further, a light-transmitting inorganic film may be applied to the heat insulating layers 23 and 24. For example, it is preferable to apply porous silica, alumina, titania, carbon, or a composite thereof to reduce thermal conductivity. These can be formed by a sol-gel method capable of forming a film from a liquid layer.
断熱層２３、２４は、膜厚２〜１００μｍ程度に形成することが望ましく、さらには４０〜５０μｍ程度が好ましい。断熱層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 23 and 24 are desirably formed to a thickness of about 2 to 100 μm, and more preferably about 40 to 50 μm. If the film thickness of the heat insulating layer is too thin, 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 translucency This is because of a decrease.
次に、保護層２５について説明する。
保護層２５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る。また、酸素ガスの透過性を極めて低い材料を適用すると、いわゆる酸素ガスバリア性が発揮され、活性酸素の発生による、光−熱変換材料の劣化を効果的に回避することができる。膜厚は０．５〜５０μｍ程度とすることが望ましい。
保護層２５の膜厚が薄すぎると充分な保護効果が得られず、厚すぎると後述する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。
Next, the protective layer 25 will be described.
The protective layer 25 can be formed using a conventionally known ultraviolet curable resin or thermosetting resin. In addition, when a material having a very low oxygen gas permeability is applied, so-called oxygen gas barrier properties are exhibited, and deterioration of the light-heat conversion material due to generation of active oxygen can be effectively avoided. The film thickness is preferably about 0.5 to 50 μm.
If the protective layer 25 is too thin, a sufficient protective effect cannot be obtained. If the protective layer 25 is too thick, the thermal conductivity deteriorates or the translucency decreases when the entire recording medium described later is uniformly heated.
本発明の可逆性多色記録媒体は、図１に示した構成に限定されるものではない。
但し、図２の可逆性感熱記録媒体２０に示すように、第１〜第３の光熱変換層１１〜１３と、第１〜第３の記録層１７〜１９とを、それぞれ、中間層を介することなく積層して、第１〜第３の可逆性感熱記録層３１〜３３を形成した構成は、中間層を有しないため本発明の範囲には属しない参考例である。また、図３の可逆性感熱記録媒体３０に示すように、第１〜第３の光熱変換層１１〜１３と、第１〜第３の記録層１７〜１９とを、それぞれ、酸素ガスバリア層２２、２６、２７を介して積層させ、これに断熱層としての機能を併用させた構成は、中間層を有しないため本発明の範囲には属しない参考例である。
さらに、支持基板１に酸素ガスバリア性をもたせてもよい。
The reversible multicolor recording medium of the present invention is not limited to the configuration shown in FIG.
However , as shown in the reversible thermosensitive recording medium 20 of FIG. 2, the first to third photothermal conversion layers 11 to 13 and the first to third recording layers 17 to 19 are respectively interposed through intermediate layers. A configuration in which the first to third reversible thermosensitive recording layers 31 to 33 are formed without being laminated is a reference example that does not belong to the scope of the present invention because it does not have an intermediate layer. Further, as shown in the reversible thermosensitive recording medium 30 of FIG. 3, the first to third photothermal conversion layers 11 to 13 and the first to third recording layers 17 to 19 are respectively replaced with the oxygen gas barrier layer 22. , 26, and 27, and a structure in which the function as a heat insulating layer is used together is a reference example that does not belong to the scope of the present invention because it does not have an intermediate layer.
Further, the support substrate 1 may have an oxygen gas barrier property.
次に、本発明の可逆性感熱記録媒体を用いた記録方法について説明する。
なお、以下においては、図１に示した、三層の可逆性感熱記録層３１〜３３が形成されている構成の可逆性感熱記録媒体１０を用いて記録、及びその消去を行う方法について説明するが、本発明はこれに限定されるものではなく、一層以上の可逆性感熱記録層が形成されている、単色や二色のみ発色可能な構成の可逆性記録媒体も同様に適用できる。
Next, a recording method using the reversible thermosensitive recording medium of the present invention will be described.
In the following, a method of recording and erasing using the reversible thermosensitive recording medium 10 having the structure in which the three layers of the reversible thermosensitive recording layers 31 to 33 shown in FIG. 1 are formed will be described. However, the present invention is not limited to this, and a reversible recording medium in which one or more reversible thermosensitive recording layers are formed and can be formed in only one color or two colors can be similarly applied.
先ず、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１７〜１９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。次に可逆性記録媒体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。 First, the entire surface is heated at a temperature at which each recording layer is decolored, for example, at a temperature of about 120 ° C., so that the first to third recording layers 17 to 19 are previously decolored. That is, in this state, it is assumed that the color of the support substrate 1 is exposed. Next, an arbitrary part of the reversible recording medium 10 is irradiated with infrared light having an arbitrarily selected wavelength and output by a semiconductor laser or the like.
例えば第１の記録層１７を発色させる場合には、第１の光−熱変換層１１に含有されている光−熱変換材料の吸収ピーク波長（λmax1）付近の赤外線を、第１の記録層１７が発色温度に達する程度のエネルギーで第１の光−熱変換層１１に照射して発熱させ、電子供与性呈色化合物と電子受容性顕・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。 For example, when the first recording layer 17 is colored, infrared light near the absorption peak wavelength (λmax1) of the light-heat conversion material contained in the first light-heat conversion layer 11 is used as the first recording layer. The first light-heat conversion layer 11 is irradiated with energy at an energy sufficient to reach a color development temperature to generate heat, causing a color development reaction between the electron donating color developing compound and the electron accepting developer / color reducing agent, Color the irradiated area.
同様に、第２の記録層１８及び第３の記録層１９についても、それぞれ、第２、及び第３の光−熱変換層１２、１３に含有されている光−熱変換材料の吸収ピーク波長（波長λmax2、λmax3）付近のレーザー光を、対応する記録層が発色温度に達する程度のエネルギーで第２、第３の光−熱変換層に照射して発熱させ、照射部分を発色させる。
このようにして可逆性感熱記録媒体１０の任意の部分を、所望の色相に発色させることができる。このとき、発振波長帯が異なるレーザー光源を、光−熱変換材料を含む記録層の数と同数使用することにより、すべての色相の記録が可能となる。
Similarly, for the second recording layer 18 and the third recording layer 19, the absorption peak wavelengths of the light-heat conversion materials contained in the second and third light-heat conversion layers 12, 13 respectively. Laser light in the vicinity of (wavelengths λmax2, λmax3) is irradiated to the second and third light-to-heat conversion layers with an energy sufficient for the corresponding recording layer to reach the color development temperature to generate heat, and the irradiated portion is colored.
In this way, an arbitrary portion of the reversible thermosensitive recording medium 10 can be developed in a desired hue. At this time, all hues can be recorded by using the same number of laser light sources having different oscillation wavelength bands as the number of recording layers including the light-heat conversion material.
またさらに、可逆性感熱記録媒体１０の同位置に、複数の波長のレーザー光を照射することにより、対応する発色色相の混合色が得られる。このとき、照射するレーザー光のエネルギーを調整することにより、混合色の色調についても表示可能となる。すなわち各記録層において、それぞれイエロー、シアン、マゼンダに発色するように設定すれば、上記の方法を採ることにより、可逆性感熱記録媒体１０の任意の部分にフルカラーの画像や種々の情報を記録することができる。 Further, by irradiating the same position of the reversible thermosensitive recording medium 10 with laser beams having a plurality of wavelengths, a mixed color of the corresponding colored hue can be obtained. At this time, the color tone of the mixed color can be displayed by adjusting the energy of the irradiated laser beam. That is, if each recording layer is set to develop yellow, cyan, and magenta, a full-color image and various information are recorded on an arbitrary portion of the reversible thermosensitive recording medium 10 by adopting the above method. be able to.
また、上記のようにして発色させた記録層において、第１〜第３の記録層１７〜１９が消色する程度の温度、例えば１２０℃に一様に加熱することにより、記録情報や画像を消去することができ、繰り返し記録を行うことができる。 Further, in the recording layer that has been colored as described above, the recording information and the image can be obtained by heating uniformly to a temperature at which the first to third recording layers 17 to 19 are decolored, for example, 120 ° C. It can be erased and repeated recording can be performed.
以下、本発明について、具体的な実施例及び比較例を挙げて説明する。
先ず、下記表１中に示す樹脂、溶媒、及び光−熱変換材料を組み合わせて塗料１〜８を作製した。
また、下記表２中に示すロイコ染料、顕・減色剤、樹脂、溶媒、及び光−熱変換材料を適宜組み合わせて混合し、ペイントコンディショナーで０．３μｍ以下となるまで粉砕し、塗料９〜１２を作製した。
Hereinafter, the present invention will be described with specific examples and comparative examples.
First, paints 1 to 8 were prepared by combining the resins, solvents, and light-heat conversion materials shown in Table 1 below.
In addition, the leuco dye, developer / color-reducing agent, resin, solvent, and light-heat conversion material shown in Table 2 below are mixed in an appropriate combination, pulverized with a paint conditioner to 0.3 μm or less, and paints 9 to 12 Was made.
上記表２中に示した、式１〜式３のロイコ染料に対応する化学式（１）〜（３）を下記に示す。
なお、Ｅｔはエチル基、Ｍｅはメチル基を表し、ｎはノルマルを表す。
Chemical formulas (1) to (3) corresponding to the leuco dyes of formulas 1 to 3 shown in Table 2 are shown below.
Et represents an ethyl group, Me represents a methyl group, and n represents normal.
上記表２中に示した、式４の顕・減色剤に対応する化学式（４）を下記に示す。 The chemical formula (4) corresponding to the developer / subtractant of formula 4 shown in Table 2 is shown below.
上記表１、２中に示した式５〜式７の光−熱変換材料（近赤外吸収色素）に対応する化学式（５）〜（７）を下記に示す。
なお、Ｍｅはメチル基を表す。
Chemical formulas (5) to (7) corresponding to the light-to-heat conversion materials (near infrared absorbing dyes) of Formulas 5 to 7 shown in Tables 1 and 2 are shown below.
Me represents a methyl group.
次に、下記表３に示すように、上記表１、表２に示した塗料を用いて、厚さ５００μｍの白色ポリエチレンテレフタレート支持基板上に塗布して成膜し、実施例１〜４、比較例１〜４の可逆性感熱記録媒体を作製した。
各層は、塗料をワイヤーバーによって塗布し、乾燥させることにより成膜した。
但し、保護層は紫外線硬化樹脂を用いて成膜した。
下記表３に示す各サンプルにおいては、塗料４及び塗料６により成膜した層が、所望の酸素透過度：１００ｍｌ/ｍ2.２４Ｈｒs.ａｔｍ.２０℃.６０%ＲＨ以下の酸素ガスバリア機能を有しているものである。
Next, as shown in Table 3 below, using the paints shown in Tables 1 and 2 above, a coating was made on a white polyethylene terephthalate support substrate having a thickness of 500 μm, and Examples 1-4 were compared. The reversible thermosensitive recording media of Examples 1 to 4 were produced.
Each layer was formed by applying paint with a wire bar and drying.
However, the protective layer was formed using an ultraviolet curable resin.
In each sample shown in Table 3 below, the layer formed by the paint 4 and the paint 6 has an oxygen gas barrier function of a desired oxygen permeability: 100 ml / m 2 .24 Hrs. Atm. 20 ° C. 60% RH or less. It is what you are doing.
また、上記表１、表２に示した塗料のうち、所定のものを、厚さ１００μmの透明ＰＥＴフィルム(酸素透過度１００ｍｌ/ｍ2.２４Ｈｒs.ａｔｍ.２０℃.６０%ＲＨ)支持基板上に順次塗布し積層成膜し、下記表４に示す実施例5、６、７及び比較例５、６のサンプルを作製した。 In addition, a predetermined one of the paints shown in Tables 1 and 2 above is applied to a transparent PET film having a thickness of 100 μm (oxygen permeability 100 ml / m 2 .24 Hrs. Atm. 20 ° C. 60% RH). The samples of Examples 5, 6, and 7 and Comparative Examples 5 and 6 shown in Table 4 below were prepared.
続いて、上述のようにして作製した、表３の実施例１〜４、及び比較例１〜４のサンプルについて、それぞれの光学特性を評価した。 Then, each optical characteristic was evaluated about the sample of Examples 1-4 of Table 3 produced as mentioned above, and Comparative Examples 1-4.
〔光学特性の評価方法〕
先ず、上述のようにして作製した各サンプルにおける、地肌の反射濃度（Ｏ．Ｄ．）を、マクベス濃度計によって測定した。
続いて、サンプルを構成する各記録層に対し、記録に用いるレーザー光の波長における記録層単独の吸光度を測定し、また分光光度計で吸収曲線を測定した。その結果、すべての記録層の、記録用レーザー光波長における記録層単独での吸光度は、１．０〜１．１程度であることが確かめられた。
なお、吸収曲線は媒体作製と同じ方法で一つの記録層を、また、光−熱変換層を設けた場合は、一つの光−熱変換層と中間層、さらに記録層を積層させた試料を、吸光度測定用透明ＰＥＴフィルム（酸素透過度１００ｍｌ/ｍ２.２４Ｈｒｓ・ａｔｍ.２０℃.６０%ＲＨ)上に形成し、これを用いて評価することとした。
[Evaluation method of optical characteristics]
First, the reflection density (OD) of the background of each sample produced as described above was measured with a Macbeth densitometer.
Subsequently, for each recording layer constituting the sample, the absorbance of the recording layer alone at the wavelength of the laser beam used for recording was measured, and the absorption curve was measured with a spectrophotometer. As a result, it was confirmed that the absorbance of the recording layer alone in all the recording layers at the recording laser beam wavelength was about 1.0 to 1.1.
It should be noted that the absorption curve is the same method as the production of the medium, and when a light-heat conversion layer is provided, a sample in which one light-heat conversion layer and an intermediate layer and a recording layer are laminated is used. , formed on the absorbance measured for a transparent PET film (oxygen permeability 100ml / m 2 .24Hrs · atm.20 ℃ .60% RH), it was decided to evaluate using the same.
〔酸素ガス透過度に対する光−熱変換材料の保存性評価〕
実施例５〜７、及び比較例６のサンプルについて、それぞれのサンプルを構成する酸素ガスバリア層の酸素透過度を測定し、さらには、光−熱変換材料の保存性についての評価を行った。
（酸素ガス透過度の測定）
酸素ガスバリア層の酸素透過度を、差圧式ガス透過率計で測定した。
用いた試料と、測定値を表5に示す。
尚、支持基板には、厚さ６０μｍのＰＥフィルム(酸素透過度２０００ｍｌ/ｍ２.２４Ｈｒｓ・ａｔｍ.２０℃.６０%ＲＨ)を用い、上記支持基板の上に、酸素ガスバリア層を形成したものを試料とした。
[Evaluation of storage stability of light-to-heat conversion material against oxygen gas permeability]
About the sample of Examples 5-7 and the comparative example 6, the oxygen permeability of the oxygen gas barrier layer which comprises each sample was measured, and also evaluation about the preservability of a light-heat conversion material was performed.
(Measurement of oxygen gas permeability)
The oxygen permeability of the oxygen gas barrier layer was measured with a differential pressure type gas permeability meter.
Table 5 shows the samples used and the measured values.
Incidentally, the supporting substrate, using a PE film having a thickness of 60 [mu] m (oxygen permeability 2000ml / m 2 .24Hrs · atm.20 ℃ .60% RH), on the supporting substrate, that forms the oxygen barrier layer Was used as a sample.
（光-熱変換材料の保存性評価）
実施例５、６、７及び比較例５、６のサンプルを用いて、光−熱変換材料の保存性についての評価を行った。
これにおいては、先ず、初期状態において、分光光度計により、光−熱変換材料の吸収曲線を測定して極大値の計測を行い、続いて、耐光性試験機を用いて、光源を白色蛍光灯とし、５０００００ｌｘ、８時間の条件で光照射を行う保存試験を行った後に、同様に、分光光度計により、光−熱変換材料の吸収曲線を測定して極大値の計測を行い、これらの比較を行った。
(Evaluation of storage stability of light-heat conversion materials)
Using the samples of Examples 5, 6, and 7 and Comparative Examples 5 and 6, the storability of the light-heat conversion material was evaluated.
In this, first, in the initial state, the absorption curve of the light-to-heat conversion material is measured by a spectrophotometer to measure the maximum value, and then the light source is set to a white fluorescent lamp using a light resistance tester. Then, after conducting a storage test in which light irradiation is performed under conditions of 500000 lx for 8 hours, similarly, the absorption curve of the light-to-heat conversion material is measured by the spectrophotometer, and the maximum value is measured. Went.
〔レーザー記録評価方法〕
上述したようにして作製した実施例１〜４、及び比較例１〜４のサンプルを用いて、以下の条件で半導体レーザーの照射を行い、記録線幅、及びベタ画像記録の反射濃度についての評価を行った。
（検証１）
先ず、初期状態においての地肌の反射濃度（Ｏ．Ｄ．）を測定し、さらにレーザー光を照射して記録を行ったときの反射濃度を測定した。
なお、この場合、所定の発振中心波長を有する半導体レーザー光を、スポット形状３０μｍ×２００μｍ、出力４５０ｍＷの条件で、照射しながら走査させた。走査の条件は、スポット形状２００μｍの軸の方向に、速度５．４ｍ／ｓ、走査間隔１５μｍで走査して記録されたベタ画像のＣＭＹ(シアン、マゼンダ、イエロー)それぞれの反射濃度をマクベス濃度計により評価した。
（検証２）
耐光性試験機により、光源を白色蛍光灯とし、５０００００ｌｘ、８時間の条件で光照射を行う保存試験を行った後に、同様に、地肌の反射濃度（Ｏ．Ｄ．）を測定し、さらにレーザー光を照射して記録を行ったときの反射濃度を測定した。記録条件は上記と同様とする。
（検証３）
次に、上記検証１で使用したサンプルを用いて、１２０℃のホットスタンプを１秒押し当て画像を消去した。
上記の記録と消去の作業を１００回繰り返し、１００回目の記録を行ったときのベタ画像と、１００回目に消去を行ったときのＣＭＹ(シアン、マゼンダ、イエロー)、それぞれの反射濃度をマクベス濃度計により評価した。
[Laser recording evaluation method]
Using the samples of Examples 1 to 4 and Comparative Examples 1 to 4 produced as described above, the semiconductor laser was irradiated under the following conditions, and the recording line width and the solid image recording reflection density were evaluated. Went.
(Verification 1)
First, the reflection density (OD) of the background in the initial state was measured, and the reflection density when recording was performed by irradiating with laser light.
In this case, scanning was performed while irradiating a semiconductor laser beam having a predetermined oscillation center wavelength under the conditions of a spot shape of 30 μm × 200 μm and an output of 450 mW. The scanning condition is that the reflection density of each solid CMY (cyan, magenta, yellow) recorded by scanning at a speed of 5.4 m / s and a scanning interval of 15 μm in the direction of the axis of the spot shape 200 μm is a Macbeth densitometer. It was evaluated by.
(Verification 2)
Using a light resistance tester, a white fluorescent lamp was used as the light source, and after a storage test in which light irradiation was performed under conditions of 500000 lx for 8 hours, similarly, the reflection density (OD) of the background was measured, and further the laser was measured. The reflection density was measured when recording was performed by irradiating light. The recording conditions are the same as above.
(Verification 3)
Next, using the sample used in Verification 1, a 120 ° C. hot stamp was pressed for 1 second to erase the image.
The recording and erasing operations described above are repeated 100 times, and the solid image when the 100th recording is performed, the CMY (cyan, magenta, yellow) when the erasing is performed for the 100th time, and the respective reflection densities are Macbeth densities. The total was evaluated.
〔評価結果〕
下記表６に、実施例５〜７及び比較例５、６のサンプルにおける、光−熱変換材料の保存特性の評価結果を示す。
また、下記表７に、実施例１〜４、及び比較例１〜４のサンプルにおける、初期のレーザー記録評価の結果を示し、下記表８に光照射試験後のレーザー記録評価の結果を示した。また、下記表９に記録と消去の作業を１００回繰り返し、１００回目の記録を行ったときのベタ画像と、１００回目に消去を行ったときのＣＭＹの反射濃度を示した。
〔Evaluation results〕
Table 6 below shows the evaluation results of the storage characteristics of the light-heat conversion materials in the samples of Examples 5 to 7 and Comparative Examples 5 and 6.
Table 7 below shows the results of the initial laser recording evaluation in the samples of Examples 1 to 4 and Comparative Examples 1 to 4, and Table 8 below shows the results of the laser recording evaluation after the light irradiation test. . Table 9 below shows the solid image when the recording and erasing operations are repeated 100 times and the 100th recording is performed, and the CMY reflection density when the erasing is performed for the 100th time.
上記表６に示すように、実施例５〜７においては、表４及び表５に示したように、支持基板上に酸素透過度が２０ｍｌ／ｍ２.２４Ｈｒｓ.ａｔｍ.２０℃.６０%ＲＨ以下の酸素ガスバリア層を形成し、かつこの酸素ガスバリア層によって、光−熱変換層である塗料１による塗膜を上層及び下層から挟み込む構成としたため、外部からの酸素ガスの侵入と活性酸素の生成を効果的に防止でき、光照射試験（保存試験）後においても、光−熱変換材料の吸光度には大きな変化がなく、良好な特性が維持され、高い保存性を有していることが確かめられた。
一方、比較例５においては、酸素バリア層を形成せず、比較例６においては、酸素透過度が２０ｍｌ／ｍ２.２４Ｈｒｓ.ａｔｍ.２０℃.６０%ＲＨを超えるものを形成した構成としたので、侵入した酸素と光により生成された活性酸素によって、光−熱変換材料が劣化してしまい、光照射試験（保存試験）後においては、著しく光吸収特性が劣化した。
上述した結果から、酸素ガスバリア層の酸素ガス透過度は、２０ｍｌ／ｍ２.２４Ｈｒｓ.ａｔｍ.２０℃.６０%ＲＨ以下であることが好ましいことが確認された。
As shown in Table 6, in Examples 5-7, Table 4 and as shown in Table 5, the oxygen permeability on a support substrate 20ml / m 2 .24Hrs.atm.20 ℃ .60% RH Since the following oxygen gas barrier layer is formed, and the coating film made of the paint 1 that is a light-heat conversion layer is sandwiched from the upper layer and the lower layer by this oxygen gas barrier layer, oxygen gas intrusion from outside and generation of active oxygen Even after the light irradiation test (storage test), the absorbance of the light-to-heat conversion material does not change greatly, it is confirmed that the good characteristics are maintained and it has high storage stability. It was.
On the other hand, in Comparative Example 5, without forming the oxygen barrier layer, in Comparative Example 6, the oxygen permeability has a structure obtained by forming what exceeds RH 20ml / m 2 .24Hrs.atm.20 ℃ .60 % Therefore, the light-heat conversion material is deteriorated by the invading oxygen and the active oxygen generated by light, and the light absorption characteristics are remarkably deteriorated after the light irradiation test (storage test).
From the results described above, the oxygen gas transmission rate of the oxygen gas barrier layer, it is preferably not more than 20ml / m 2 .24Hrs.atm.20 ℃ .60% RH was confirmed.
上記表７に示すように、実施例１〜４においては、発振中心波長が８００、８６０、９４０ｎｍの各レーザー光を用いて記録を行ったとき、良好なイエロー、マゼンタ、シアンの発色が得られ、色かぶりも生じなかった。また複数のレーザー光を同時に照射すると、それに対応する中間色が明瞭な発色で得られた。
また、レーザー光で記録を行った後、１２０℃のホットスタンプを１秒間接触させることにより、すべての画像を消去することができ、消去後の透明性が良好であった。
また、実施例１〜４においては、表１及び表３に示したように、可逆性感熱記録層の上層側と下層側に酸素ガスバリア層を形成して、これによって挟み込まれた構成としたため、外部からの酸素ガスの侵入と活性酸素の生成を効果的に防止できたので、繰り返し記録後の色調が極めて明瞭であることが確かめられた。
また、上記表８に示すように、実施例１〜４においては、光照射試験（保存試験）後においても、良好な発色が得られた。
As shown in Table 7 above, in Examples 1 to 4, good yellow, magenta, and cyan colors were obtained when recording was performed using laser beams having oscillation center wavelengths of 800, 860, and 940 nm. Also, no color cast occurred. When a plurality of laser beams were irradiated at the same time, a corresponding intermediate color was obtained with a clear color.
Further, after recording with laser light, all images could be erased by bringing a hot stamp at 120 ° C. into contact for 1 second, and the transparency after erasure was good.
Further, in Examples 1 to 4, as shown in Tables 1 and 3, the oxygen gas barrier layer was formed on the upper layer side and the lower layer side of the reversible thermosensitive recording layer, and thus sandwiched by this, Since the entry of oxygen gas from the outside and the generation of active oxygen were effectively prevented, it was confirmed that the color tone after repeated recording was very clear.
Moreover, as shown in the said Table 8, in Examples 1-4, favorable color development was obtained even after the light irradiation test (storage test).
一方、比較例１〜４においては、表１及び表３に示したように、可逆性感熱記録層の上層側と下層側から、酸素ガスバリア層によって遮蔽しなかったため、外部からの酸素ガスの侵入と活性酸素の生成を充分に防止できず、表８に示すように、光照射試験（保存試験）後において、良好な発色が得られなかった。 On the other hand, in Comparative Examples 1 to 4, as shown in Tables 1 and 3, the oxygen gas barrier layer did not shield the reversible thermosensitive recording layer from the upper layer side and the lower layer side. As shown in Table 8, good color development was not obtained after the light irradiation test (storage test).
さらに、上記表９に示すように、実施例１〜４においては、１００回記録と消去とを繰り返した後も、良好なイエロー、マゼンタ、シアンの発色が得られ、色かぶりも生じなかった。また、１２０℃のホットスタンプを１秒間接触させたときの消え残り反射濃度が非常に小さく、ほぼすべての画像を消去することができた。
一方、比較例１〜４においては、可逆性感熱記録層の上層側と下層側から、酸素ガスバリア層によって遮蔽しなかったため、外部からの酸素ガスの侵入と活性酸素の生成を充分に防止できず、光−熱変換材料が劣化していき、１００回記録と消去とを繰り返した後は、イエロー、マゼンタ、シアンの発色性が著しく低下した。また、１２０℃のホットスタンプを１秒間接触させたときの消え残りがあり、すべての画像を消去することができなかった。
Further, as shown in Table 9 above, in Examples 1 to 4, good yellow, magenta, and cyan colors were obtained and no color cast occurred even after 100 times of recording and erasing were repeated. Further, the reflection density after disappearance when the 120 ° C. hot stamp was contacted for 1 second was very small, and almost all images could be erased.
On the other hand, in Comparative Examples 1 to 4, since the oxygen gas barrier layer did not shield the reversible thermosensitive recording layer from the upper layer side and the lower layer side, entry of oxygen gas from the outside and generation of active oxygen could not be sufficiently prevented. The light-to-heat conversion material deteriorates, and after 100 times of recording and erasing, the color developability of yellow, magenta and cyan is remarkably lowered. In addition, there was unerased residue when a 120 ° C. hot stamp was contacted for 1 second, and all images could not be erased.
上述した結果から明らかなように、本発明によれば、支持基板の面方向に、特定の波長域の近赤外線を吸収して発熱する光−熱変換材料と、温度変化に応じて無色・着色の二状態を可逆的に変化する感熱発色性組成物が、樹脂中に含有されて形成された可逆性感熱記録層の存在する可逆性感熱記録媒体において、外部から酸素ガスの侵入を防ぐ酸素ガスバリア性を有する酸素ガスバリア層を設けることにより、活性酸素の生成が防止され、光−熱変換材料の耐光性の劣化を確実に回避することが可能となり、繰り返して発・消色の変換を行った場合においても、長期に亘って初期と同等の記録画質が維持できた。 As is clear from the above-described results, according to the present invention, a light-to-heat conversion material that generates heat by absorbing near infrared rays in a specific wavelength region in the surface direction of the support substrate, and colorless and colored according to temperature changes. An oxygen gas barrier that prevents oxygen gas from entering from the outside in a reversible thermosensitive recording medium having a reversible thermosensitive recording layer formed by including a thermosensitive coloring composition that reversibly changes between the two states in a resin. By providing an oxygen gas barrier layer having the property, the generation of active oxygen is prevented, and it is possible to reliably avoid the deterioration of the light resistance of the light-to-heat conversion material. Even in this case, it was possible to maintain the same recording image quality as the initial recording over a long period of time.
１……支持基板、１０……可逆性感熱記録媒体、１１……第１の光−熱変換層、１２……第２の光−熱変換層、１３……第３の光−熱変換層、１４，１５，１６……中間層、
１７……第１の記録層、１８……第２の記録層、１９……第３の記録層、２０……可逆性感熱記録媒体、２１，２２，２６，２７……酸素ガスバリア層、２３，２４……断熱層、２５……保護層、３０……可逆性感熱記録媒体、３１……第１の可逆性感熱記録層、３２……第２の可逆性感熱記録層、３３……第３の可逆性感熱記録層
DESCRIPTION OF SYMBOLS 1 ... Support substrate, 10 ... Reversible thermosensitive recording medium, 11 ... 1st light-heat conversion layer, 12 ... 2nd light-heat conversion layer, 13 ... 3rd light-heat conversion layer , 14, 15, 16 ... intermediate layer,
DESCRIPTION OF SYMBOLS 17 ... 1st recording layer, 18 ... 2nd recording layer, 19 ... 3rd recording layer, 20 ... Reversible thermosensitive recording medium, 21, 22, 26, 27 ... Oxygen gas barrier layer, 23 , 24 ... heat insulating layer, 25 ... protective layer, 30 ... reversible thermosensitive recording medium, 31 ... first reversible thermosensitive recording layer, 32 ... second reversible thermosensitive recording layer, 33 ... first 3 Reversible thermosensitive recording layer
Claims (5)
特定の波長領域の近赤外線を吸収して発熱する光−熱変換材料と、温度変化に応じて、無色・着色の二状態を可逆的に変化する感熱発色性組成物とが、樹脂中に含有されている可逆性感熱記録層と、
外部から前記可逆性感熱記録層への酸素侵入を防ぐ酸素ガスバリア性を有する酸素ガスバリア層とを備え、
前記可逆性感熱記録層は、前記光−熱変換材料を含有する光−熱変換層と、前記感熱発色性組成物が樹脂中に含有されている記録層と、酸素ガスバリア性を有する中間層と、を有し、
前記光−熱変換層と前記記録層とが、前記中間層を介して積層されてなり、
前記酸素ガスバリア層は、膜厚０．１〜２０μｍであり、
前記中間層は、膜厚０．１〜１０μｍであり、
前記支持基板上の積層順を基準として、前記可逆性感熱記録層の、上層側と下層側に前記酸素ガスバリア層が設けられてなり、当該酸素ガスバリア層により、前記可逆性感熱記録層が挟み込まれてなる構成を有している可逆性感熱記録媒体。 In the direction of the surface of the support substrate,
The resin contains a light-to-heat conversion material that generates heat by absorbing near-infrared rays in a specific wavelength region, and a thermosensitive coloring composition that reversibly changes between colorless and colored states according to temperature changes. A reversible thermosensitive recording layer,
An oxygen gas barrier layer having an oxygen gas barrier property to prevent oxygen from entering the reversible thermosensitive recording layer from the outside,
The reversible thermosensitive recording layer includes a light-heat converting layer containing the light-heat converting material, a recording layer containing the thermosensitive coloring composition in a resin, and an intermediate layer having oxygen gas barrier properties. Have
The light-heat conversion layer and the recording layer are laminated via the intermediate layer,
The oxygen gas barrier layer has a thickness of 0.1 to 20 μm,
The intermediate layer has a thickness of 0.1 to 10 μm,
The oxygen gas barrier layer is provided on the upper layer side and the lower layer side of the reversible thermosensitive recording layer on the basis of the stacking order on the support substrate, and the reversible thermosensitive recording layer is sandwiched by the oxygen gas barrier layer. A reversible thermosensitive recording medium having the structure as described above.
前記二以上の可逆性感熱記録層においては、それぞれ異なる色調に発色する感熱発色性組成物が含有され、それぞれ異なる波長領域の近赤外線を吸収して発熱する光−熱変換材料が含有されてなる請求項１に記載の可逆性感熱記録媒体。 Two or more reversible thermosensitive recording layers are separated and laminated in the surface direction of the support substrate,
Each of the two or more reversible thermosensitive recording layers contains a thermosensitive coloring composition that develops colors different from each other, and contains a light-to-heat conversion material that generates heat by absorbing near infrared rays in different wavelength regions. The reversible thermosensitive recording medium according to claim 1.
膜厚２０μｍ、２０℃、６０％ＲＨの条件下において、酸素透過度が、２０ｍｌ/ｍ2・２４Ｈｒｓ・ａｔｍ以下である請求項１に記載の可逆性感熱記録媒体。 The oxygen gas barrier layer is
2. The reversible thermosensitive recording medium according to claim 1, wherein the oxygen permeability is 20 ml / m 2 · 24 Hrs · atm or less under conditions of a film thickness of 20 μm, 20 ° C., and 60% RH.
前記光−熱変換層と前記記録層とは、これらを構成する樹脂が互いに相溶しないように材料選定がなされている請求項１に記載の可逆性感熱記録媒体。 The light-heat conversion layer contains the light-heat conversion material in a resin,
The reversible thermosensitive recording medium according to claim 1, wherein materials of the light-heat conversion layer and the recording layer are selected so that resins constituting them are not compatible with each other.
特定の波長領域の近赤外線を吸収して発熱する光−熱変換材料と、温度変化に応じて、無色・着色の二状態を可逆的に変化する感熱発色性組成物とが、樹脂中に含有されている可逆性感熱記録層と、
外部から前記可逆性感熱記録層への酸素侵入を防ぐ酸素ガスバリア性を有する酸素ガスバリア層とを備え、
前記可逆性感熱記録層は、前記光−熱変換材料を含有する光−熱変換層と、前記感熱発色性組成物が樹脂中に含有されている記録層と、酸素ガスバリア性を有する中間層と、を有し、
前記光−熱変換層と前記記録層とが、前記中間層を介して積層されてなり、
前記酸素ガスバリア層は、膜厚０．１〜２０μｍであり、
前記中間層は、膜厚０．１〜１０μｍであり、
前記支持基板上の積層順を基準として、前記可逆性感熱記録層の、上層側と下層側に前記酸素ガスバリア層が設けられてなり、当該酸素ガスバリア層により、前記可逆性感熱記録層が挟み込まれてなる構成の可逆性感熱記録媒体を用いて、
任意に選択された波長の近赤外線を照射することによって、記録または消去を行う記録方法。 In the direction of the surface of the support substrate,
The resin contains a light-to-heat conversion material that generates heat by absorbing near-infrared rays in a specific wavelength region, and a thermosensitive coloring composition that reversibly changes between colorless and colored states according to temperature changes. A reversible thermosensitive recording layer,
An oxygen gas barrier layer having an oxygen gas barrier property to prevent oxygen from entering the reversible thermosensitive recording layer from the outside,
The reversible thermosensitive recording layer includes a light-heat converting layer containing the light-heat converting material, a recording layer containing the thermosensitive coloring composition in a resin, and an intermediate layer having oxygen gas barrier properties. Have
The light-heat conversion layer and the recording layer are laminated via the intermediate layer,
The oxygen gas barrier layer has a thickness of 0.1 to 20 μm,
The intermediate layer has a thickness of 0.1 to 10 μm,
The oxygen gas barrier layer is provided on the upper layer side and the lower layer side of the reversible thermosensitive recording layer on the basis of the stacking order on the support substrate, and the reversible thermosensitive recording layer is sandwiched by the oxygen gas barrier layer. Using a reversible thermosensitive recording medium having the structure
A recording method in which recording or erasing is performed by irradiating near infrared rays having an arbitrarily selected wavelength.
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