JP2005131911A - Recording medium and coloring composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording medium capable of realizing clear and sharp coloring and excellent contrast. <P>SOLUTION: The recording medium 10 has recording layers 11 to 13 formed in the face direction of a support substrate 1. The recording layer contains at least developing/subtractive agents comprising an electron donative coloring compound and an electron acceptive compound. The recording layer is changed into a coloring state by the reaction between the coloring compound and the developing/subtractive agents. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording medium for recording a desired image or data by heat irradiation or light irradiation, and a color forming composition.

  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.

  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, etc. In addition, it has been put into practical use in applications such as visualization and readability of the balance and other recorded information, and is also being put into practical use in copying machines and printers.

  Various proposals have been made regarding the reversible thermosensitive recording medium and the recording method using the same (see, for example, 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.

  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 developing / 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.

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.

  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.

  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.

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.

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, in this reversible thermosensitive multicolor recording medium, the light-heat conversion layer (laser light absorption layer) and the recording layer are provided separately and the light-heat conversion layer contains a binder. Without forming a light-absorbing material dissolved in an organic solvent, it has a disadvantage that the display accuracy is deteriorated because it absorbs laser light in a very wide wavelength region. ing. In addition, the laser light absorption layer formed by such a method has light absorption even in the visible region, so that the transparency of the recording layer is deteriorated in the erased state, and the recording accuracy is deteriorated. Also have.
Furthermore, since the above public information uses red, green, and blue as the three primary colors, the intermediate color is dark and the color reproducibility is poor, so that full color display is impossible.

Further, leuco dyes used in heat-sensitive recording media that have been put to practical use in the past mostly have a black or blue hue in order to ensure good visibility of the display medium.
That is, in the past, in order to realize full color display, development of a leuco dye that develops colors in three primary colors of yellow, magenta, and cyan has not progressed. Also in the examples described in Patent Document 24 below, Red, green, and blue are used as the three primary colors. As a result, the obtained intermediate color becomes dark, has poor reproducibility, and has a problem that adequate clarity is not practically obtained.

JP 54-119377 A JP 55-154198 A JP-A-63-39377 JP-A-63-41186 JP-A-2-188293 JP-A-2-188294 JP-A-5-124360 Japanese Patent Laid-Open No. 7-108761 Japanese Patent Laid-Open No. 7-179043 Japanese Patent Laid-Open No. 5-62189 JP-A-8-80682 JP 2000-198275 A JP-A-8-58245 JP 2000-25338 A JP-A-6-305247 JP-A-6-328844 JP-A-6-79970 JP-A-8-164669 JP-A-8-300825 Japanese Patent Laid-Open No. 9-52445 JP 11-138997 A JP 2001-162941 A JP 2002-59654 A JP 2001-1645 A

As described above, there is an increasing demand for a clear and vivid color tone with respect to a recording medium capable of performing thermal recording, but sufficient research has been made especially in the case of high lightness colors. As a result, no practically satisfactory recording medium has been realized.
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 recording medium and a color forming composition were provided.

  In the present invention, a recording layer is formed in the surface direction of the support substrate. The recording layer includes at least a color-forming compound having an electron donating property represented by the following general formula (1) and an electron accepting property. A recording medium containing a developing / color-reducing agent having a colorant, and changing the recording layer into a colored state by a reaction between the color developing compound and the developing / color-reducing agent is provided.

  However, R <1>, R <2> represents a C1-C6 alkyl group, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocyclic ring together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are simultaneously a carbon atom or a nitrogen atom, or one of X and Y is a carbon atom and the other is a nitrogen atom.

  In the present invention, a recording layer is formed in the surface direction of the support substrate. The recording layer includes at least a color-forming compound having an electron donating property represented by the following general formula (2) and an electron. Provided is a recording medium which contains a receptive developer / subtractor and is adapted to change the recording layer into a colored state by a reaction between the color developing compound and the developer / subtractor. To do.

  However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.

  In the present invention, a plurality of recording layers are separated and laminated in the surface direction of the support substrate, and each of the plurality of recording layers has at least an electron donating property having a different color tone. And a color developing compound having an electron accepting property in the recording layer that causes magenta color development among the plurality of recording layers. And a recording medium which changes the recording layer to a colored state by a reaction between the color developing compound and the developer / subtractor.

  However, R <1>, R <2> represents a C1-C6 alkyl group, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocyclic ring together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are simultaneously a carbon atom or a nitrogen atom, or one of X and Y is a carbon atom and the other is a nitrogen atom.

  Further, in the present invention, a plurality of recording layers are separated and laminated in the surface direction of the support substrate, and each of the plurality of recording layers includes a color-forming compound having an electron donating property of different colors. And a color developing compound having electron-donating properties in the recording layer that causes magenta color development among the plurality of recording layers. And a recording medium which changes the recording layer to a colored state by a reaction between the color developing compound and the developer / subtractor.

  However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.

  In the present invention, a recording layer is formed in the surface direction of the support substrate. The recording layer absorbs at least infrared rays in a specific wavelength region and generates heat, and the following general A reaction between the color developing compound represented by the formula (1) and the color developing compound having an electron accepting property and a color developing / color reducing agent having an electron accepting property. Thus, a recording medium adapted to change the recording layer to a colored state is provided.

  However, R <1>, R <2> represents a C1-C6 alkyl group, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocyclic ring together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are simultaneously a carbon atom or a nitrogen atom, or one of X and Y is a carbon atom and the other is a nitrogen atom.

  In the present invention, a recording layer is formed in the surface direction of the support substrate. The recording layer absorbs at least infrared rays in a specific wavelength region and generates heat, and the following general A reaction between the color developing compound represented by the formula (2) and a color developing compound having an electron donating property and a color developing / color reducing agent having an electron accepting property. Thus, a recording medium adapted to change the recording layer to a colored state is provided.

  However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.

  In the present invention, a plurality of recording layers are separated and laminated in the surface direction of the support substrate, and each of the plurality of recording layers absorbs at least infrared rays in a specific wavelength region and generates heat. A recording layer containing a light-heat conversion material, a color developing compound having electron donating properties of different colors, and a developer / color-reducing agent having an electron accepting property, and of which a magenta color is developed among a plurality of recording layers The color-providing compound having electron donating property is a compound represented by the following general formula (1), and the recording layer is brought into a colored state by the reaction between the color-forming compound and the developer / color-reducing agent. A recording medium adapted to change is provided.

  However, R <1>, R <2> represents a C1-C6 alkyl group, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocyclic ring together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are simultaneously a carbon atom or a nitrogen atom, or one of X and Y is a carbon atom and the other is a nitrogen atom.

  In the present invention, a plurality of recording layers are separated and laminated in the surface direction of the support substrate, and each of the plurality of recording layers absorbs at least infrared rays in a specific wavelength region and generates heat. A recording that contains a light-to-heat conversion material, a color developing compound having electron donating properties of different colors, and a developer / color-reducing agent having electron accepting properties, and of which a magenta color is developed among these recording layers. The color-forming compound having an electron donating property in the layer is a compound represented by the following general formula (2), and the recording layer is colored by a reaction between the color-forming compound and the developing / color-reducing agent. Provided is a recording medium adapted to change into a state.

  However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.

  In the present invention, a recording layer that reversibly develops a specific color tone is formed in the surface direction of the support substrate, and the recording layer generates heat by absorbing at least infrared rays in a specific wavelength range. Contains a light-to-heat conversion material, a color developing compound having an electron donating property represented by the following general formula (1), and a developer / color reducing agent having an electron accepting property represented by the following general formula (3) Provided is a recording medium in which a recording layer is reversibly changed into two states of color development and color erasure by a reversible reaction between a color former and a developer / subtractor. .

  However, R <1>, R <2> represents a C1-C6 alkyl group, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocyclic ring together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are simultaneously a carbon atom or a nitrogen atom, or one of X and Y is a carbon atom and the other is a nitrogen atom.

However, X consists of any one of OH, COOH, halogen, and H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-,- NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, and The total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH-, _{-CH (C n H 2n OH)} - ( where, n = 0 to 5) becomes more either, a is 0 or 1 der And things.

  In the present invention, a recording layer that reversibly develops a specific color tone is formed in the surface direction of the support substrate, and the recording layer generates heat by absorbing at least infrared rays in a specific wavelength range. Contains a light-to-heat conversion material, a color developing compound having an electron donating property represented by the following general formula (2), and a developer / color reducing agent having an electron accepting property represented by the following general formula (3) Provided is a recording medium in which a recording layer is reversibly changed into two states of color development and color erasure by a reversible reaction between a color former and a developer / subtractor. .

  However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.

However, X consists of any one of OH, COOH, halogen, and H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-,- NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, and The total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH-, _{-CH (C n H 2n OH)} - ( where, n = 0 to 5) becomes more either, a is 0 or 1 der And things.

  In 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 each of the plurality of recording layers has at least a specific wavelength. A plurality of recording layers comprising a light-to-heat conversion material that absorbs infrared rays and generates heat, a color developing compound having electron donating properties of different colors, and a developer / color-reducing agent having electron accepting properties. Among them, the color-providing compound having electron donating property in the recording layer that causes magenta color development is represented by the following general formula (1), and the developing / color-reducing agent having electron accepting property is represented by the following general formula. It consists of the compound represented by (3) and reversibly changes the recording layer into two states of color development and decoloration by a reversible reaction between the color former and the developer / color-reducing agent. A recording medium configured as described above is provided.

  However, R <1>, R <2> represents a C1-C6 alkyl group, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocyclic ring together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are simultaneously a carbon atom or a nitrogen atom, or one of X and Y is a carbon atom and the other is a nitrogen atom.

However, X consists of any one of OH, COOH, halogen, and H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-,- NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, and The total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH-, _{-CH (C n H 2n OH)} - ( where, n = 0 to 5) becomes more either, a is 0 or 1 der And things.

  In 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 each of the plurality of recording layers has at least a specific wavelength. A plurality of recording layers containing a light-to-heat conversion material that generates heat by absorbing infrared rays in the region, a color developing compound having electron donating properties of different colors, and a developer / color-reducing agent having electron accepting properties. Among them, the color-providing compound having electron donating property in the recording layer that causes magenta color development is represented by the following general formula (2), and the developer / subtractor having electron accepting property is represented by the following general formula. It consists of the compound represented by (3) and reversibly changes the recording layer into two states of color development and decoloration by a reversible reaction between the color former and the developer / color-reducing agent. A recording medium configured as described above is provided.

  However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.

However, X consists of any one of OH, COOH, halogen, and H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-,- NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, and The total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH-, _{-CH (C n H 2n OH)} - ( where, n = 0 to 5) becomes more either, a is 0 or 1 der And things.

  In the present invention, a combination of an electron-donating color developing compound represented by the following general formula (1) and a developer / color-reducing agent comprising at least one compound represented by the following general formula (3) And a color forming composition.

  However, R <1>, R <2> represents a C1-C6 alkyl group, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocyclic ring together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are simultaneously a carbon atom or a nitrogen atom, or one of X and Y is a carbon atom and the other is a nitrogen atom.

However, X consists of any one of OH, COOH, halogen, and H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-,- NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, and The total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH-, _{-CH (C n H 2n OH)} - ( where, n = 0 to 5) becomes more either, a is 0 or 1 der And things.

  In the present invention, a combination of an electron-donating color developing compound represented by the following general formula (2) and a developer / color-reducing agent comprising at least one compound represented by the following general formula (3) And a color forming composition.

  However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are simultaneously carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.

However, X consists of any one of OH, COOH, halogen, and H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-,- NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, and The total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH-, _{-CH (C n H 2n OH)} - ( where, n = 0 to 5) becomes more either, a is 0 or 1 der And things.

  According to the present invention, by specifying the structure of the color developing compound and further specifying the structure of the color developing / subtracting agent that causes the color development reaction in combination with this, it is possible to realize color development with a very clear and vivid color tone. .

According to the recording medium of the present invention, with regard to the developer / color-reducing agent and color developing compound contained in the recording layer, a clear and clear color tone can be obtained by specifying the compound having a predetermined chemical structure. In addition, an image having sufficient stability and clarity could be formed.
In particular, even when performing high-speed recording using an infrared laser, clear color development and clear contrast could be realized.
Furthermore, on a recording medium having a recording layer that develops three primary colors of yellow, cyan, and magenta, a vivid full-color image can be formed, and particularly excellent results are obtained with respect to the reproducibility of intermediate colors.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
FIG. 1 shows a schematic sectional view of an example of a recording medium in the present invention.
In the 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.
In the following, a description will be given of a recording medium in which the first to third recording layers 11 to 13 are three-layered recording layers that develop yellow, cyan, and magenta, respectively, and can form a full-color image as a whole. However, the recording medium of the present invention is not limited to this configuration, and may be a single-layer recording medium in which one recording layer is formed on the support substrate 1 or a two-layer that develops an arbitrary color tone. It may be a multilayer type recording medium on which the above recording layer is formed.

  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 visible with white or metallic color in order to improve the visibility when information is recorded on the finally obtained recording medium 10. It is preferable to form with a material having high reflectance to light.

  The first to third recording layers 11 to 13 are made of a material capable of forming a colored state by heat. Each of the color-forming compounds having electron donating properties described in detail below, for example, a leuco dye, and predetermined electrons It is assumed that it is formed by applying a paint containing a receptive developer / color-reducing agent and dissolving them in a resin base material. Other predetermined additives and sensitizers may be included as appropriate.

When the recording layers 11 to 13 are colored to perform predetermined recording, for example, a thermal head can be applied. That is, by heating a desired portion of the recording layer with a thermal head, a reaction is caused between a color developing compound having an electron donating property, such as a leuco dye, and a developer / color reducing agent having a predetermined electron accepting property. To develop color.
At this time, it is assumed that the first to third recording layers 11 to 13 each contain a color-forming compound capable of coloring yellow, cyan, and magenta, respectively, and a developer / color-reducing agent having electron acceptability, If the material has temperature selectivity for each layer, a full color image can be formed as a whole by controlling the set temperature of the thermal head.

  The reaction between the color-providing compound having an electron donating property and the developing / color-reducing agent having an electron accepting property may be irreversible or reversible. If the recording medium is a so-called write-once type recording medium and is reversible, it can be a recording medium capable of repeated recording that can be switched between a decolored state and a colored state.

Further, the recording is not limited to an example in which recording is performed by a thermal head, and infrared rays having different wavelengths (λ ₁ , λ ₂ , λ _{3 in} FIG. 1) are absorbed in the first to third recording layers 11 to 13. Thus, the recording may be performed by irradiating with a laser beam having a predetermined wavelength.
In this case, the recording layer is irradiated with laser light selected from any _one of the above-mentioned λ ₁ , λ ₂ , and λ ₃ with respect to the wavelength, and a predetermined portion is heated in the recording layers 11 to 13, thereby providing an electron donating property. A color reaction is caused between a color developing compound having a colorant, for example, a leuco dye, and a developing / color-reducing agent having a predetermined electron accepting property.
In this case, each of the first to third recording layers 11 to 13 contains a color developable compound capable of coloring yellow, cyan, and magenta, and controls the wavelength of the laser light to be irradiated. As a result, a full-color image can be formed.

Next, the electron donating color developing compound applied in the recording medium 10 of the present invention will be described.
In the present invention, a compound represented by the following general formula (1) or at least one compound represented by the following general formula (2) can be applied as the color developing compound that develops magenta.

However, R <1>, R <2> represents a C1-C6 alkyl group, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocyclic ring together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are simultaneously a carbon atom or a nitrogen atom, or one of X and Y is a carbon atom and the other is a nitrogen atom.
In addition, when R1, R2, R3 is an alkyl group, since the color development stability decreases as the number of carbon atoms increases, the number of carbon atoms is preferably 1-7.

  However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.

Next, the developing / color-reducing agent having electron acceptability will be described.
As the developer / color reducing agent, at least one compound represented by the following general formula (3) is applied.

However, X consists of any one of OH, COOH, halogen, and H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-,- NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, and The total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH-, _{-CH (C n H 2n OH)} - ( where, n = 0 to 5) becomes more either, a is 0 or 1 der And things.

  Note that X, Y, Z, R7, and R8 constituting the chemical formula of the developer / color-reducing agent are recording / erasing sensitivities required for the target recording medium 10, that is, solubility in a solvent or polymer, melting point, coloring / It shall be appropriately selected and combined according to various conditions such as the temperature that can be erased.

Next, the light-to-heat conversion material contained in the recording layers 11 to 13 when the recording medium 10 of the present invention is to be recorded by laser light irradiation will be described.
As the light-to-heat conversion material, for example, phthalocyanine dyes, cyanine dyes, metal complex dyes, diimmonium dyes and the like that are generally used as infrared absorbing pigments that hardly absorb in the visible wavelength range 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.
For example, the first recording layer 11 absorbs infrared light with a wavelength λ ₁ , the second recording layer 12 absorbs infrared light with a wavelength λ ₂ , and the third recording layer 13 generates heat by absorbing infrared light with a wavelength λ _3. Is selected so that the wavelength λ ₁ , the wavelength λ ₂ , and the wavelength λ ₃ do not overlap each other.
These thermosensitive coloring composition and light-heat converting composition may be mixed and contained in the recording layer, or each may be contained separately during recording. As a method for separating / separating these compositions, a method for forming a recording layer by mixing the thermosensitive coloring composition and the light-heat conversion composition in a resin binder that is incompatible with each other, or either composition Can be encapsulated in microcapsules and contained in the recording layer. Further, a single recording layer may be formed by laminating layers containing each of the reversible thermosensitive coloring composition and the light-heat conversion composition.
In the method of forming one recording layer by laminating layers containing the respective compositions, the layer containing the light-heat conversion composition is placed on the support substrate side, and the layer containing the thermosensitive coloring composition is placed on the recording light. It is more preferable to arrange on the incident side. The reason for this is that, as understood from Lambert-Beer's law, when recording light is irradiated, the layer containing the light-heat conversion composition is heated to a higher temperature on the surface on which the recording light is incident. Therefore, such an arrangement can efficiently transfer heat to the layer containing the thermosensitive coloring composition.
When the former two compositions are mixed and used, there is an advantage that the process is simplified, which is preferable. On the other hand, the latter method in which both compositions are separated and independent can prevent the composition and the like from deteriorating due to an undesirable reaction between the compositions. Therefore, either method may be selected according to the application to be used and the request.
Further, when the two compositions are separated and independent, the light-heat conversion composition is preferably used after being uniformly dissolved in a resin binder or the like. As described in JP-A-2001-1645, when an infrared absorbing dye is used in a crystalline state or a thin film state without using a resin binder, the absorption spectrum in the near infrared region is crushed due to aggregation or dimerization of the dye. This is not preferable because a problem such as fogging or a decrease in recording sensitivity occurs.

  Examples of the resin base material 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, 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 Etc. Various additives such as an ultraviolet absorber may be used in combination with these resins as necessary.

  The first to third recording layers 11 to 13 are prepared by using various additives such as the color developing compound, developer / decolorizer, and sensitizer, and, if necessary, a light-heat conversion material, using a solvent. It can form by apply | coating the coating material dissolved and adjusted in resin to each predetermined formation surface. The solvent to be used is preferably a solvent having high solubility of the developer / color reducing agent.

The first to third recording layers 11 to 13 are preferably formed to a thickness of about 1 to 20 μm, and more preferably about 1 to 10 μm. The optimum film thickness is 2 to 3 μm.
If the film thickness of the recording layer is less than 1 μm, a sufficient color density cannot be obtained. If the film thickness exceeds 20 μm, the heat capacity of the recording layers 11 to 13 increases, and the color development and decoloring properties deteriorate. is there.

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.
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.
Moreover, the heat insulation layers 14 and 15 can also be formed using a translucent inorganic film. For example, when porous silica, alumina, titania, carbon, or a composite thereof is used, the thermal conductivity is lowered and the heat insulating effect is high, which is preferable. These can be formed by a sol-gel method capable of forming a film from a liquid layer.
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.

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.

  Next, the principle of performing multicolor recording using the recording medium 10 shown in FIG. 1 will be described. In the following, the first to third recording layers 11 to 13 contained the above-described color developing compound, various additives such as a developer / subtractor, a sensitizer, and a light-heat conversion material. The so-called laser irradiation type recording medium 10 will be described as an example.

First, the first principle of multicolor recording will be described.
The entire surface of the recording medium 10 shown in FIG. 1 is heated at a temperature at which each recording layer is decolored, for example, at a temperature of about 120 ° C., then cooled, and the first to third recording layers 11 to 13 are preliminarily formed. Leave in a decolored state. That is, in this state, it is assumed that the color of the support substrate 1 is exposed.
Next, an arbitrary part of the recording medium 10 is irradiated with an infrared ray 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 reaction between the color developing compound and the electron donating developer / color-reducing agent is caused to develop a color on the irradiated part.
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 recording medium 10 can be colored, and a full-color image can be formed and various information can be recorded.

  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 poorly soluble in the polymer of the developer / color reducing agent used in the recording layer formed on the upper layer of the predetermined recording layer and the recording layer is dispersed and cloudy, the irradiation is performed. Since the infrared rays are reflected and scattered by the upper layer, the recording sensitivity is remarkably lowered. For this reason, in the laminated recording medium 10 having the configuration as shown in FIG. 1, it is important to use a developer / color-reducing agent having a high solubility in a solvent or polymer for forming the recording layer.

  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.

  Further, the entire 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. The data can be erased, and recording can be repeated by performing the operation as described above.

Next, the second principle of multicolor recording will be described.
First, the recording medium 10 shown in FIG. 1 is heated entirely 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., then cooled, and the first to third recording layers 11 are then cooled. All of ˜13 are previously colored.
Next, an arbitrary part of the recording medium 10 is irradiated with an infrared ray 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 recording medium 10 can be erased, and a full-color image can be formed and various information can be recorded.

  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.

  Further, the entire recording medium 10 partially decolored or colored as described above is uniformly heated at a temperature at which all the recording layers are colored, for example, 200 ° C., and then cooled. As a result, the recorded information and images can be erased, and by performing the above-described operation, recording can be repeated again.

Which of the recording methods shown in the first principle and the second principle is applied to the recording medium 10 of the present invention depends on the characteristics of the recording layer and the performance of the recording light source. Select as appropriate.
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).

  Next, the recording medium of the present invention will be described with specific examples and comparative examples, but the present invention is not limited to the examples shown below.

[Example 1]
In the following, as shown in FIG. 1, 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 formed on the support substrate 1. Thus, a so-called reversible multicolor recording type recording medium having a structure having three recording layers laminated sequentially and capable of reversibly forming a colored state and a decolored state is produced.

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 3 μm.
The absorbance of the first recording layer 11 with light having a wavelength of 920 nm was 1.0.

(Composition)
Leuco dye (substance shown in chemical formula (4) below): 1 part by weight

Developer / color-reducing agent (substance shown in chemical formula (5) below): 4 parts by weight

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 (manufactured by HW SANDS, SDA7775, absorption wavelength peak in recording layer: 933 nm)
Tetrahydrofuran (THF): 140 parts by weight

  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.

  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. A thickness of 3 μm was formed. The absorbance of the second recording layer 12 with light having a wavelength of 860 nm was 1.0.

(Composition)
Leuco dye: 1.5 parts by weight (manufactured by Yamada Chemical Co., Ltd., H-3035 (substance shown in the following chemical formula (6)))

Developer / color-reducing agent (substance shown in chemical formula (5) below): 4 parts by weight

Vinyl chloride vinyl acetate copolymer: 10 parts by weight (90% vinyl chloride, 10% vinyl acetate, MW 115000)
Cyanine-based infrared absorbing dye: 0.08 part by weight (manufactured by HW SANDS, SDA5688, absorption wavelength peak in recording layer 861 nm)
Tetrahydrofuran (THF): 140 parts by weight

  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.

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 3 μm.
The absorbance of the third recording layer 13 with light having a wavelength of 800 nm was 1.0.

(Composition)
Leuco dye: 1.7 parts by weight (substance shown in chemical formula (7) below)

Developer / color-reducing agent (substance shown in chemical formula (5) below): 4 parts by weight

Vinyl chloride vinyl acetate copolymer: 10 parts by weight (90% vinyl chloride, 10% vinyl acetate, MW 115000)
Cyanine infrared absorbing dye: 0.08 parts by weight (CY-10 manufactured by Nippon Kayaku Co., Ltd., absorption wavelength peak in recording layer: 798 nm)
Tetrahydrofuran (THF): 140 parts by weight

  A protective layer 16 having a thickness of about 2 μm was formed on the third recording layer 13 using an ultraviolet curable resin, and the target recording medium 10 was produced.

A specific example of the method for synthesizing the developer / color-reducing agent represented by the chemical formula (5) contained in the first to third recording layers 11 to 13 will be described.
A 500 ml flask equipped with a stirrer was charged with 10.9 g of 4-Aminophenol, 29.5 g of n-Octadecyl isocyanate, and 250 ml of tetrahydrofuran (THF), respectively, 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 95%, and the melting point of the target product was 145 ° C.

A specific example of a method for synthesizing a leuco dye that develops a magenta color represented by the chemical formula (7) contained in the third recording layer 13 will be described.
In a 200 ml flask equipped with a stirrer, 200 g of 70% sulfuric acid was added, and 31.4 g of 2- (4-diethylamino-2-hydroxybenzoyl) nicotinic acid and 28.8 g of β-naphthol were added at room temperature. This was heated to 100 ° C. and reacted for 6 hours. 400 g of ice water was prepared in a 1000 ml flask with a separate stirrer, and the reaction product was poured into this. The precipitate was separated by filtration and added to a 1000 ml flask equipped with a separate stirrer, and 200 ml of toluene and 200 ml of water were further added. To this 48% caustic soda was added until alkaline. The mixture was heated to 85 ° C. and heated for 10 minutes, followed by liquid separation to obtain a toluene layer. The toluene layer was concentrated to obtain a crude product. 100 ml of methanol was added to this, heated to reflux, and then cooled to room temperature with stirring to form crystals. When this was isolated, the yield was 16.9 g and the melting point was 224 ° C.

  The recording medium 10 produced as described above was uniformly heated using a ceramic bar heated to 120 ° C., and the first, second and third recording layers 11, 12 and 13 were decolored. A sample was used.

[Example 2]
The leuco dye that develops a magenta color applied in Example 1 described above was changed to a compound represented by the following chemical formula (8). Other conditions were the same as in Example 1, and a sample was prepared.
The compound represented by the chemical formula (8) was synthesized by using 31.4 g of 2- (4-diethylamino-2-hydroxybenzoyl) nicotinic acid in the method for synthesizing the leuco dye represented by the chemical formula (7) above as 2- [4- ( N-isopentyl-N-ethylamino) -2-hydroxybenzoyl] nicotinic acid, except that it was changed to 34.2 g. The yield was 20.9 g and the melting point was 129 ° C.

Example 3
The leuco dye that develops a magenta color applied in Example 1 described above was changed to a compound represented by the following chemical formula (9). Other conditions were the same as in Example 1, and a sample was prepared.
The compound represented by the chemical formula (9) was synthesized from 31.4 g of 2- (4-diethylamino-2-hydroxybenzoyl) nicotinic acid in the method for synthesizing the leuco dye represented by the above chemical formula (7). -2-Hydroxybenzoyl) benzoic acid is the same except that it is changed to 31.3 g. The yield was 33.7 g and the melting point was 222 ° C.

Example 4
The leuco dye that develops a magenta color applied in Example 1 described above was changed to a compound represented by the following chemical formula (10). Other conditions were the same as in Example 1, and a sample was prepared.
A synthesis method of the compound represented by the chemical formula (10) will be described.
In a 200 ml flask equipped with a stirrer, 50 ml of acetic acid, 31.5 g of 3- (4-diethylamino-2-hydroxybenzoyl) pyrazine-2-carboxylic acid, and 21.6 g of β-naphthol were added. This was heated to 60 ° C., 50 ml of acetic anhydride was added dropwise over 1 hour and reacted at the same temperature for 10 hours. In a 1000 ml flask with a separate stirrer, 200 ml of water and 200 ml of toluene were prepared, and the reaction product was poured into this. It heated to 80 degreeC and liquid-separated and the toluene layer was obtained, 200 ml of water was added to this, and it heated and made it 80 degreeC. 48% caustic soda was added to the solution until it became alkaline, and then liquid separation was performed to obtain a toluene layer. The toluene layer was concentrated to obtain a crude product. 100 ml of methanol was added to this, heated to reflux, and then cooled to room temperature with stirring to form crystals. When this was isolated, the yield was 19.3 g and the melting point was 230 ° C.

Example 5
The leuco dye that develops a magenta color applied in Example 1 described above was changed to a compound represented by the following chemical formula (11). Other conditions were the same as in Example 1, and a sample was prepared.
The compound represented by the chemical formula (11) was synthesized using 31.5 g of 3- (4-diethylamino-2-hydroxybenzoyl) pyrazine-2-carboxylic acid in the method for synthesizing the leuco dye represented by the chemical formula (10), The same applies except for changing to 34.3 g of (4-diethylamino-2-hydroxybenzoyl) -5,6-dimethylpyrazine-2-carboxylic acid. The yield was 23.0 g, and the melting point was 246 ° C.

Example 6
The leuco dye that develops a magenta color 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.
In the method of synthesizing the compound represented by the chemical formula (12), 100 ml of toluene, 31.8 g of 1-ethyl-2-methylindole, and 14.8 g of phthalic anhydride were added to a 300 ml flask equipped with a stirrer and heated to 60 ° C. To this, 30 ml of acetic anhydride was added dropwise over 1 hour and reacted at the same temperature for 6 hours. In a 1000 ml flask equipped with a separate stirrer, 200 ml of water and 100 ml of toluene were prepared, and the reaction product was poured into this. The mixture was heated to 80 ° C. and separated to obtain a toluene layer, and 200 ml of water was added to the toluene layer and heated to 80 ° C. 48% caustic soda was added to the solution until it became alkaline, and then liquid separation was performed to obtain a toluene layer. The toluene layer was concentrated to obtain a crude product. 150 ml of methanol was added to this, heated to reflux, and then cooled to room temperature with stirring to form crystals. When this was isolated, the yield was 38.1 g, and the melting point was 224 ° C.

Example 7
The leuco dye that develops a magenta color 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 chemical formula (13) is changed from 31.8 g of 1-ethyl-2-methylindole to 37.4 g of 1-butyl-2-methylindole in the synthesis method of the leuco dye represented by the chemical formula (12). Other than that, the same shall apply. The yield was 38.1 g, and the melting point was 224 ° C.

Example 8
The leuco dye that develops a magenta color applied in Example 1 described above was changed to a compound represented by the following chemical formula (14). Other conditions were the same as in Example 1, and a sample was prepared.
The method for synthesizing the compound represented by the chemical formula (14) is the same except that 14.8 g of phthalic anhydride in the method for synthesizing the leuco dye represented by the chemical formula (12) is changed to 14.9 g of quinolinic anhydride. The yield was 31.4 g, and the melting point was 218 ° C.

Example 9
The leuco dye that develops a magenta color applied in Example 1 described above 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.
The compound represented by the chemical formula (15) was synthesized from 31.8 g of 1-ethyl-2-methylindole in the method of synthesizing the leuco dye represented by the chemical formula (12) to 37.4 g of 1-butyl-2-methylindole. Further, the same applies except that 14.8 g of phthalic anhydride is changed to 14.9 g of quinolinic anhydride. The yield was 34.2 g, and the melting point was 164 ° C.

Example 10
The leuco dye that develops a magenta color 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.
The compound represented by the chemical formula (16) was synthesized from 31.8 g of 1-ethyl-2-methylindole in the leuco dye synthesis method represented by the chemical formula (12) to 40.2 g of 1-pentyl-2-methylindole. Further, the same applies except that 14.8 g of phthalic anhydride is changed to 14.9 g of quinolinic anhydride. The yield was 34.6 g, and the melting point was 133 ° C.

[Comparative Example 1]
The leuco dye that develops a magenta color 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.

[Comparative Example 2]
The leuco dye that develops a magenta color 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.

[Comparative Example 3]
The leuco dye that develops a magenta color 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.

The recording line width, reflection density, absorption wavelength, and erasing characteristics of each recording medium sample produced as described above were evaluated.
Evaluation methods and evaluation results are shown below.

(Laser recording evaluation)
Scanning was performed while irradiating the medium with laser light of a semiconductor laser having an oscillation center wavelength selected from 800 nm, 860 nm, and 920 nm under the conditions of a spot shape of 30 μm × 200 μm and an output of 400 mW. As the scanning condition, the line width of a line recorded by scanning at a speed of 3.5 m / s in the direction of the axis of the spot shape of 200 μm was evaluated. Further, when a single laser beam corresponding to each recording layer was scanned at a speed of 3.5 m / s at intervals of 20 μm and recorded, the change in the reflection density of each CMY of the solid image was measured with a Macbeth densitometer. evaluated. The absorption wavelength (λmax) at that time was measured with a spectrophotometer.

(Erase characteristics evaluation)
The recording medium used for the reflection density measurement described above was pressed for 1 second with a hot press heated to 100 ° C., and then the reflection density of the sample was evaluated with a Macbeth densitometer.

(Evaluation results)
For the recording media of [Examples 1 to 10] and [Comparative Examples 1 to 3], the measurement results of recording line width, reflection density, and reflection density after erasure are shown in [Table 1] below.

As shown in Table 1, in the recording media of [Examples 1 to 10], the three primary colors of yellow, cyan, and magenta have a clear color tone, no color cast, and extremely excellent color reproducibility for intermediate colors. As a result, it was possible to form a full-color image that was clear as a whole and highly stable.
In [Examples 1 to 10], it was found that the recording line width of the third recording layer was wider than that of [Comparative Examples 1 to 3] and had excellent recording sensitivity.
Further, in [Examples 1 to 10], it was found that the solid image of the third recording layer had a high reflection density, and the irradiation light was converted into heat with high efficiency, and the recording layer was colored.

On the other hand, in [Comparative Example 1], a conventionally known color developing compound that develops a red color is used. However, when high-speed recording is performed using laser light, a practically sufficient magenta color is obtained. The visibility deteriorated.
Further, in [Comparative Examples 2 and 3], the hue in the third recording layer is orange, which is inappropriate as a hue for showing full-color display, and the reproducibility of intermediate colors is deteriorated.

  As described above, a color-forming compound that is contained in the third recording layer of the recording medium shown in [Examples 1 to 10] and develops a magenta color represented by the general formula (1) or (2), In addition, it was confirmed that the color forming composition comprising the combination of the developer and the color reducing agent represented by the general formula (3) can realize excellent color-developing properties, contrast, fineness, and high sensitivity.

1 shows a schematic cross-sectional view of an example of a reversible multicolor recording medium of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Support substrate, 10 ... Recording medium, 11 ... 1st recording layer, 12 ... 2nd recording layer, 13 ... 3rd recording layer, 14, 15 ... Heat insulation layer, 16 ... Protective layer

Claims (15)

A recording layer is formed in the surface direction of the support substrate,
The recording layer contains at least a color developing compound having an electron donating property represented by the following general formula (1), and a developer / color-reducing agent having an electron accepting property.
A recording medium, wherein the recording layer is changed to a colored state by a reaction between the color developing compound and the developer / color reducing agent.

(However, R1 and R2 represent an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocycle together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are carbon atoms or nitrogen atoms, or one of X and Y is a carbon atom and the other is a nitrogen atom.) A recording layer is formed in the surface direction of the support substrate,
The recording layer contains at least a color developing compound having an electron donating property represented by the following general formula (2), and a developer / color-reducing agent having an electron accepting property.
A recording medium, wherein the recording layer is changed to a colored state by a reaction between the color developing compound and the developer / color reducing agent.

(However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are simultaneously carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.) A plurality of recording layers are separated and laminated in the surface direction of the support substrate,
Each of the plurality of recording layers contains at least a color-forming compound having electron donating properties of different colors, and a developer / color-reducing agent having electron acceptability,
Of the plurality of recording layers, the color-providing compound having an electron donating property in the recording layer that causes magenta color development is a compound represented by the following general formula (1):
A recording medium, wherein the recording layer is changed to a colored state by a reaction between the color developing compound and the developer / color reducing agent.

(However, R1 and R2 represent an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocycle together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are carbon atoms or nitrogen atoms, or one of X and Y is a carbon atom and the other is a nitrogen atom.) A plurality of recording layers are separated and laminated in the surface direction of the support substrate,
Each of the plurality of recording layers contains at least a color-forming compound having electron donating properties of different colors, and a developer / color-reducing agent having electron acceptability,
Among the plurality of recording layers, the color-providing compound having an electron donating property in the recording layer that causes magenta color development is a compound represented by the following general formula (2):
A recording medium, wherein the recording layer is changed to a colored state by a reaction between the color developing compound and the developer / color reducing agent.

(However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are simultaneously carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.)
A recording layer is formed in the surface direction of the support substrate,
The recording layer includes at least a light-to-heat conversion material that generates heat by absorbing infrared rays in a specific wavelength region, a color-forming compound having an electron donating property represented by the following general formula (1), and electron acceptance. A developer and a color-reducing agent having properties,
A recording medium, wherein the recording layer is changed to a colored state by a reaction between the color developing compound and the developer / color reducing agent.

(However, R1 and R2 represent an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocycle together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are carbon atoms or nitrogen atoms, or one of X and Y is a carbon atom and the other is a nitrogen atom.) A recording layer is formed in the surface direction of the support substrate,
The recording layer includes at least a light-to-heat conversion material that generates heat by absorbing infrared rays in a specific wavelength region, a color-forming compound having an electron donating property represented by the following general formula (2), and electron acceptance. A developer and a color-reducing agent having properties,
A recording medium, wherein the recording layer is changed to a colored state by a reaction between the color developing compound and the developer / color reducing agent.

(However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are simultaneously carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.) A plurality of recording layers are separated and laminated in the surface direction of the support substrate,
Each of the plurality of recording layers has at least a light-to-heat conversion material that generates heat by absorbing infrared rays in a specific wavelength range, a color-forming compound having electron donating properties with different colors, and an electron-accepting property. Contains developer and color-reducing agent,
Of the plurality of recording layers, the color-providing compound having an electron donating property in the recording layer that causes magenta color development is a compound represented by the following general formula (1):
A recording medium, wherein the recording layer is changed to a colored state by a reaction between the color developing compound and the developer / color reducing agent.

(However, R1 and R2 represent an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocycle together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are carbon atoms or nitrogen atoms, or one of X and Y is a carbon atom and the other is a nitrogen atom.) A plurality of recording layers are separated and laminated in the surface direction of the support substrate,
Each of the plurality of recording layers has at least a light-to-heat conversion material that generates heat by absorbing infrared rays in a specific wavelength range, a color-forming compound having electron donating properties with different colors, and an electron-accepting property. Contains developer and color-reducing agent,
Among the plurality of recording layers, the color-providing compound having an electron donating property in the recording layer that causes magenta color development is a compound represented by the following general formula (2):
A recording medium, wherein the recording layer is changed to a colored state by a reaction between the color developing compound and the developer / color reducing agent.

(However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are simultaneously carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.) The recording medium according to any one of claims 1 to 8, wherein the developer / color-reducing agent comprises at least one compound represented by the following general formula (3).

(Where X is any of OH, COOH, halogen, H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-, -NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, And the total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH- _{, -CH (C n H 2n OH} ) - ( where, n = 0 to 5) becomes more either, a is 0 or 1 And shall.) A recording layer that reversibly develops a specific color tone is formed in the surface direction of the support substrate,
The recording layer includes at least a light-to-heat conversion material that generates heat by absorbing infrared rays in a specific wavelength region, a color-forming compound having an electron donating property represented by the following general formula (1), and the following general A developer and a color reducing agent having an electron accepting property represented by the formula (3),
Recording characterized in that the recording layer is reversibly changed into two states of color development and color erasure by a reversible reaction between the color developing compound and the developer / color reducing agent. Medium.

(However, R1 and R2 represent an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocycle together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are carbon atoms or nitrogen atoms, or one of X and Y is a carbon atom and the other is a nitrogen atom.)

(Where X is any of OH, COOH, halogen, H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-, -NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, And the total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH- _{, -CH (C n H 2n OH} ) - ( where, n = 0 to 5) becomes more either, a is 0 or 1 And shall.) A recording layer that reversibly develops a specific color tone is formed in the surface direction of the support substrate,
The recording layer includes at least a light-to-heat conversion material that generates heat by absorbing infrared rays in a specific wavelength region, a color-forming compound having an electron donating property represented by the following general formula (2), and the following general A developer and a color reducing agent having an electron accepting property represented by the formula (3),
Recording characterized in that the recording layer is reversibly changed into two states of color development and color erasure by a reversible reaction between the color developing compound and the developer / color reducing agent. Medium.

(However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are simultaneously carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.)

(Where X is any of OH, COOH, halogen, H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-, -NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, And the total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH- _{, -CH (C n H 2n OH} ) - ( where, n = 0 to 5) becomes more either, a is 0 or 1 And shall.) In the surface direction of the support substrate, a plurality of recording layers that reversibly develop different colors are separated and stacked,
Each of the plurality of recording layers has at least a light-to-heat conversion material that generates heat by absorbing infrared rays in a specific wavelength range, a color-forming compound having electron donating properties with different colors, and an electron-accepting property. Contains developer and color-reducing agent,
Among the plurality of recording layers, the color-providing compound having an electron donating property in the recording layer that causes magenta color development is represented by the following general formula (1):
The electron-accepting developer / color-reducing agent is composed of a compound represented by the following general formula (3):
Recording characterized in that the recording layer is reversibly changed into two states of color development and color erasure by a reversible reaction between the color developing compound and the developer / color reducing agent. Medium.

(However, R1 and R2 represent an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocycle together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are carbon atoms or nitrogen atoms, or one of X and Y is a carbon atom and the other is a nitrogen atom.)

(Where X is any of OH, COOH, halogen, H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-, -NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, And the total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH- _{, -CH (C n H 2n OH} ) - ( where, n = 0 to 5) becomes more either, a is 0 or 1 And shall.) In the surface direction of the support substrate, a plurality of recording layers that reversibly develop different colors are separated and stacked,
In each of the plurality of recording layers, at least a light-to-heat conversion material that generates heat by absorbing infrared rays in a specific wavelength region, a color-forming compound having an electron donating property with a different color tone, and a visible light having an electron-accepting property.・ Contains a color reducing agent,
Among the plurality of recording layers, the color-providing compound having electron donating properties in the recording layer that causes magenta color development is represented by the following general formula (2):
The electron-accepting developer / color-reducing agent is composed of a compound represented by the following general formula (3):
Recording characterized in that the recording layer is reversibly changed into two states of color development and color erasure by a reversible reaction between the color developing compound and the developer / color reducing agent. Medium.

(However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are simultaneously carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.)

(Where X is any of OH, COOH, halogen, H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-, -NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, And the total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH- _{, -CH (C n H 2n OH} ) - ( where, n = 0 to 5) becomes more either, a is 0 or 1 And shall.) It is characterized by comprising a combination of an electron donating compound represented by the following general formula (1) and a developer / color-reducing agent comprising at least one compound represented by the following general formula (3). Color-forming composition.

(However, R1 and R2 represent an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group, and a cyclohexyl group. R1 and R2 may form a 5- to 7-membered nitrogen-containing heterocycle together with the nitrogen atom. R3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X and Y are carbon atoms or nitrogen atoms, or one of X and Y is a carbon atom and the other is a nitrogen atom.)

(Where X is any of OH, COOH, halogen, H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-, -NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, And the total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH- _{, -CH (C n H 2n OH} ) - ( where, n = 0 to 5) becomes more either, a is 0 or 1 And shall.) It is characterized by comprising a combination of an electron-donating colorant compound represented by the following general formula (2) and a developer / color-reducing agent comprising at least one compound represented by the following general formula (3). Color-forming composition.

(However, R4 and R5 are alkyl groups, R6 is a hydrogen atom or an alkyl group, X and Y are simultaneously carbon atoms or nitrogen atoms, or either one is a nitrogen atom and the other is a nitrogen atom.)

(Where X is any of OH, COOH, halogen, H, Y is -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-, -NHCONCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, R7 and R8 are each an alkyl group having 2 to 26 carbon atoms, And the total number of carbon atoms of R7 and R8 is 9 to 30, and Z is -COO-, -OCO-, -O-, -CONH-, -NHCO-, -NHCONH-, -NHNHCO-, -CONHNH- _{, -CH (C n H 2n OH} ) - ( where, n = 0 to 5) becomes more either, a is 0 or 1 And shall.)

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