JPH0562189A - Rewritable recording medium and its recording method - Google Patents

Abstract

PURPOSE:To provide a recording medium wherein a recording operation and an erasing operation can be performed reversibly by means of light or heat by a recording layer wherein the following are contained: coloring particles whose surface is provided with a crystal nucleus formation ability as crystalline organic molecules; crystalline organic molecules; and a transparent matrix polymer. CONSTITUTION:A polyester sheet provided with an aluminum vapor-deposited reflection layer 2 is used as a substarte 1. The reflection layer 2 is coated to a thickness of 13mum, with a liquid in which the following are dispersed and dissolved in tetrahydrofuran: hydroxystearic acid as crystalline organic molcules; a phenol-based antioxidant as an additive; a vinyl chloride-vinyl acetate copolyer as a transparent matrix polmer; and red glass beads in an average of 15mum as coloring particles 4. Thereby, a recording layer 3 is formed. In addition, a UV-curing acryl resin is coated as a surface protective layer 6. The title recording medium becomes transparent at about 70 to 90 deg.C, and its recording operation can be performed at 100 deg.C by using a semiconductor laser. The recording durability of the recording medium amounts to about 600 times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium capable of reversibly recording and erasing by light or heat, which enables color recording, and is particularly advantageous for application as an optical recording medium. is there. INDUSTRIAL APPLICABILITY The present invention is widely used for a rewritable memory card with a display function, which is used as a prepaid card such as a commuter ticket, a ticket, and a coupon ticket, an IC card, a color copying machine, a recording paper for facsimile, and an optical disk.

[0002]

2. Description of the Related Art Conventionally, recording materials used for rewritable recording media include heat mode materials and photon mode materials.

The heat mode material can be a reversible thermosensitive recording material having a light absorption property, such as a phase change type recording material and a magneto-optical recording material. Organic reversible thermosensitive recording materials include thermosensitive dye recording materials that reversibly develop and decolor by a combination of a leuco dye and a color developer and a decoloring agent, and melting of organic crystal particles in a matrix polymer. A phase-change type reversible thermosensitive recording material that utilizes the change in transparency of particles depending on its coagulation conditions, and a liquid crystal polymer such as cholesteric liquid crystal that is transparent by utilizing the thermal behavior of its molecular arrangement. There is a method of changing sex.

The present invention utilizes the melting and solidification behavior of organic crystal molecules in a matrix polymer to change the transparency depending on the solidification conditions of the matrix polymer. Regarding materials, the crystalline fine particles in the matrix polymer are melted and solidified again by the heat of light, and depending on the conditions, there is a difference in the transparency caused by the solidification morphology such as a polycrystalline state, a single crystal state, or an amorphous state. It is generated and recorded. This heat-sensitive recording material is composed of a combination of a matrix polymer and the following fusible organic molecules, as disclosed in, for example, Japanese Patent Laid-Open No. 54-119377, and can constitute a wide variety of recording materials. The fusible organic molecules disclosed herein include aliphatic and aromatic alcohols, carboxylic acids, amines, amides and their halides, sulfides, and the like. On the other hand, as the matrix polymer, general polymers such as polyester, polyamide, polyacrylic acid, styrene, silicone, polyvinyl chloride, polyvinylidene chloride and polyacrylonitrile are disclosed. Further, a recording material obtained by improving this and further adding carbon black for light-heat conversion and adding an antioxidant are disclosed in, for example, JP-A-57-82087 and 57-82088.

[0005]

However, although any of the above-mentioned conventional examples discloses a fusible organic molecule, a matrix polymer and carbon black, their mutual compatibility / dispersibility and light absorber effect, etc. No details are given, and there is a problem in that it is not possible to obtain a high-density recording that is excellent in recording image quality and resolution. There is also a problem that color recording cannot be performed.

Therefore, a first object of the present invention is to provide a rewritable recording medium which is new and excellent in quality by using a reversible thermosensitive recording layer having a novel structure.

A second object of the present invention is to provide a rewritable recording method in which the recording medium is widely applied to, for example, cards with a display function, facsimile sheets, optical memories and the like.

[0008]

In order to achieve the above-mentioned first object, a rewritable recording medium of the present invention has a crystalline organic molecule, a transparent matrix polymer and a crystal nucleating ability on the surface of a substrate. And a recording layer containing the colored particles. The second object of the present invention is to record a recording medium according to the present invention, in which crystalline organic molecules near the surface of the colored particles in the recording layer are made transparent by a melting / cooling process in a low temperature mode, and then, for example, absorption of colored particles Wavelength light is irradiated, and the colored particles absorb the absorption wavelength to carry out a melting / cooling process in a high temperature mode to cloud the crystalline organic molecule layer near the surface of the colored particles in the recording layer to It is a method of hiding and recording.

[0009]

The rewritable recording medium of the present invention utilizes the phenomenon that the crystalline organic molecules contained in the recording layer become transparent and cloudy upon cooling after heating and melting depending on the heating temperature. In particular, on the surface of colored particles having the ability to form crystal nuclei on the surface, the two states of the transparent state and the cloudy state behave bistable. When heated and melted at a temperature near the melting point of the crystalline organic molecule, the solidified crystalline organic molecule is in a transparent state, and when it is melted at a higher temperature and then cooled, the solidified crystalline organic molecule becomes cloudy. In the present invention, heating to be melted and then cooled and solidified to be transparent is called a low temperature mode, and heating to be cloudy is called a high temperature mode. The reason for this phenomenon is not clear, but when cooled after being heated in a high temperature mode, the cooling rate is fast and the crystalline organic molecules are cooled to below the melting point in a supercooled state, so they crystallize at once and become fine crystals and become cloudy. However, when heated and cooled in a low temperature mode, it slowly solidifies, and it is assumed that the single crystal grows large and becomes transparent.

Based on such a principle, the rewritable recording medium of the present invention emits a recording and displaying color by colored particles having a crystal nucleus forming ability on the surface, and two heating temperatures of crystalline organic molecules surrounding the colored particles. Recording is carried out in two states when solidified after the mode, namely, hiding (white turbidity) and visible (transparent). Since the colored particles are visible in the transparent portion of the rewritable recording medium of the present invention, the color of the colored particles is shown. In the case of a single color, the color of the colored particles and white can be recorded, and when the colored particles are colored in a plurality of colors, the recording of a plurality of colors and white can be performed. That is, in the case of optical recording, when the colored particles are irradiated with the absorbed light, the temperature of the colored particles rises in the high temperature mode, and after cooling, the vicinity of the surface becomes cloudy. On the other hand, when the transmitted light of the colored particles is irradiated to the colored particles, the temperature of the light absorbing layer below the recording layer rises, the lower side of the colored particles rises in the high temperature mode, and after cooling, the vicinity of the surface becomes cloudy and becomes upper. Emboss the color of colored particles. Further, in the gaps between the colored particles, light is directly radiated and absorbed by the light absorbing layer, and the lower portion of the recording layer rises in temperature in the high temperature mode and is cooled, and then becomes cloudy and white.

[0011]

EXAMPLE FIG. 1 shows a typical example of a rewritable recording medium using the colored particles of the present invention. In FIG. 1, a recording layer 3 of the present invention is formed on a substrate 1 on which a reflective film 2 is formed. A surface protective layer 6 is further formed on the recording layer 3. As shown in FIG. 1, the recording layer 3 contains colored particles 4, crystalline organic molecules and a matrix polymer. For example, the outer layer of the colored particles 4 is formed by a high temperature mode that absorbs light having an absorption wavelength of the colored particles 4. 5 becomes cloudy. FIG. 2 is an enlarged view of the crystalline organic molecules in the matrix polymer of the recording layer 3 forming the outer shell layer 5 near the surface of the colored particles 4.
become that way. The outer shell layer 5 is a transparent outer shell layer 5A by a heating / cooling process (low temperature mode) at a low temperature, and a high temperature heating / cooling process (high temperature module) by irradiation with light having a wavelength absorbed by the colored particles 4, for example. -D), it takes two states with the opaque outer shell layer 5B that becomes cloudy and scatters light. In the case of recording with single color particles, this corresponds to erasing / recording.

Color recording of the rewritable recording medium of the present invention is performed, for example, by the structure shown in FIG. The colored particles are composed of light-transmissive colored particles of the three primary colors of red (R), green (G), and blue (B), respectively, and the recording layer 3 including these is colored particles 4R, 4G of the three primary colors as shown in FIG. 4B
Second recording layer 7 composed of crystalline organic molecules and a transparent matrix polymer under the recording layer 3.
The light absorption layer 8 is provided via the. The light absorption layer 8 absorbs the transmitted light of the above colored particles and raises the temperature. Here, the second recording layer 7 is newly provided in order to improve the contrast, but since the lower parts of the respective colored particles 4R, 4G, 4B in the recording layer 3 have the same function, as shown in FIG. In some cases, the second recording layer 7 is not always necessary. Around each colored particle 4R, 4G and 4B in the recording layer 3 of FIG.
Similar to FIG. 1, it has a crystalline organic molecule and a matrix polymer, and further, a surface protective layer 6 is provided on the recording layer 3. First, the recording layer 3 and the second recording layer 7 are made transparent by a melting / cooling process in a low temperature mode. As a result, the transparent colored particles 4R, 4G, and 4B develop respective colors, but the transmitted light of each particle is absorbed by the light absorbing layer 8 therebelow, and when viewed from the surface protective layer 6 side, black is obtained. Present. This is the initial state before recording. When the light of the color image is applied to this as shown in FIG. 3, the R, G, and
The particles 4R, 4G, and 4B colored B absorb light other than their own transmitted light and rise in temperature. The crystalline organic molecules in the vicinity of the particles whose temperature has risen are melted, and due to the melting / cooling process in this high temperature mode, they become cloudy and hide the color of the colored particles. That is, in the portion irradiated with white light, the temperature of all the colored particles of the three primary colors absorbs light other than the transmitted light, and the temperature rises, and all colored particles form a white turbid layer on the outer shell of the particle and thus appear white. .. Regarding the recording of the color portion, for example, when green light is irradiated, only the green colored particles 4G do not absorb the light, so that the surroundings of the green colored particles 4G remain transparent, but the green transmitted light absorbs the light. The second recording layer 7 provided below the particles 4G is made cloudy by being absorbed in the layer 8 and being heated and melted / cooled in a high temperature mode, and when viewed from the surface protective layer 6 side, the color of the colored particles 4G, that is, green. Present. The red colored particles 4R and the blue colored particles 4B irradiated with green light both absorb light and rise in temperature, and become turbid and white in the vicinity of their surfaces. Therefore, the portion irradiated with green light exhibits a green color. A red recording can be formed by the same mechanism when red light is irradiated. On the other hand, in the black portion not irradiated with light, all the colored particles are not turbid and the red colored particles 4R, the green colored particles 4G and the blue colored particles 4B respectively transmit light, and the light absorbing layer 8 immediately below each particle. Each of the transmitted light is absorbed by and the resulting black color appears.

The structure in which the second recording layer 7 is not used in FIG. 4 has the same principle. In this case, the lower part of the recording layer 3 functions as the second recording layer 7.

It should be noted that in FIGS.
Although the form using three kinds of R, 4G and 4B is shown, it is needless to say that the same operation can be performed even in the case of single color or plural color (multicolor) recording. In the case of single color recording,
The light absorption layer 8 shown in FIGS. 3 and 4 does not need to have a function of absorbing light, and may be the reflection film 2 shown in FIG. 1, for example, and the recording layer 3 may be directly formed on the substrate 1. It may be provided. Furthermore, the colored particles 4 in the case of monochromatic recording do not necessarily have to be transparent to light, and may be opaque when black is not reproduced. Further, when the black color is not reproduced, the light absorption layer 8 and the second recording layer 7 thereon are unnecessary.

As described above, according to the recording method of the present invention,
Rewritable recording is possible in each case, and the degree of clouding can be controlled depending on the heating temperature of the high-temperature mode, and recording can be performed with different hiding power, so halftone recording is also possible and rewriting is possible with a simple configuration. Enables recording,
It can also be used for multicolor recording and color recording.

The substrate 1 used in the present invention includes, for example, glass, metal, polymer film and the like, and an appropriate material can be selected depending on the use of the recording medium of the present invention. However, when the substrate 1 is made of a metal material having a high reflectance such as aluminum or stainless steel alone, for example, a metal vapor-deposited film or a composite material laminated with a metal foil, the recording medium of the present invention is as shown in FIG. The reflective film 2 can be formed. Further, the reflection film 2 used in the present invention can be supported by, for example, a polymer film that has been subjected to an opaque treatment, in addition to the above-mentioned metallic materials,
It is preferable that any of the reflection films 2 can be used for recording and display by reflected light, the contrast of a recorded image can be increased, and the color purity can be improved.

Materials used for the colored particles 4 of the present invention include organic or inorganic substances such as coloring pigments, dyes or polymers of thermosetting resins colored with dyes or pigments, and glass. The colored particles 4 have a function of forming crystal nuclei on at least the surface. Among these materials for the colored particles 4, polymer or glass is preferable because the particle size can be easily adjusted freely. The colored particles 4 of the present invention may be transparent or opaque. However, colored particles 4
Only when multicolor recording such as color recording is performed by using transparent particles for the colored particles 4 as shown in FIG.
It is necessary to arrange one layer in the recording layer 3. The function of forming crystal nuclei of the colored particles 4 can be achieved by, for example, binding a crystalline organic molecule to the material of the colored particles 4 or binding a polar group or the like that promotes crystal growth. Among them, it is preferable to bond a hydrogen-bonding group such as a hydroxyl group, a carboxyl group, an amino group or an amide group to at least the surface of the colored particles 4 because the selection of the crystalline organic molecular material is widened.

The shape of the colored particles 4 may be any of, for example, spherical particles, disk-shaped particles, hexagonal plate-shaped particles, cubic particles, and the like, and the most closely packed state improves the image quality and the recording density, which is desirable. .. In particular, spherical particles are preferable because the production method is relatively easy and the packing rate of particles is easily improved. The size of the colored particles 4 is preferably small because it directly affects the resolving power of the recorded image, but considering the yield of the colored particles 4, 1 to 100 μm is suitable. Also,
The particle size distribution of the colored particles 4 depends on the surface shape of the recording layer 3 produced,
The resolution of the recorded image and the filling rate of the colored particles 4 in the recording layer 3 are affected, and a wider particle size distribution is preferable for the filling rate and the surface shape of the recording layer 3, but heating in a high temperature mode
As a result of cooling, the concentration of white turbidity on the surface of the colored particles 4 is proportional to the light absorption ratio of the colored particles 4. Therefore, it is preferable that the particle size distribution of the colored particles 4 is as uniform as possible. Therefore, the colored particles 4
The particle size distribution of is determined according to the surface shape of the recording layer 3 and the reproducibility of the recorded image. In addition, the crystalline organic molecules and the matrix polymer forming the recording layer 3 are mixed with the colored particles 4, and the recording layer 3 can be formed by applying a usual method such as a printing or casting method, which is suitable for multicolor recording. As a means for arranging one layer of colored particles 4 for this purpose, various methods such as lithography, precision printing and electrophotography can be used, and the recording layer 3 can be easily constructed.

The light absorbing layer 8 may have a hue that absorbs the transmitted light of the colored particles 4 provided in the upper layer, but it is generally a black layer.

The crystalline organic molecule used in the recording layer 3 and the second recording layer 7 of the present invention is a colorless low molecule,
A molecule having a hydrogen bonding group is preferable in view of easy crystallinity. Among hydrogen bonding groups, an organic molecule having at least one of a carboxyl group, a hydroxyxyl group, an amino group, and an amide group is preferable because of high crystal growth property, and a molecule having a melting point of 60 to 120 ° C. It is desirable to use since the heat energy or light intensity required for recording or erasing can be reduced. Further, in order to adjust the melting point of these molecules, these crystalline organic molecules may be further formed into a eutectic or complex with a separate alcohol such as higher alcohol, fatty acid, alkylamine, oxycarboxylic acid, dicarboxylic acid, diamine, alkylene glycol. It is also possible to form crystalline organic molecules having a desired melting point.

The matrix polymer used in the present invention interacts with the crystalline organic molecule and exerts a great influence on the crystallization behavior. Specific examples thereof include transparent polymers such as polyester, polyacrylic acid ester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, cellulose acetate, polyvinyl butyral, polystyrene, and styrene-butadiene copolymer, but hydrogen bond A transparent matrix polymer partially containing a group is suitable for controlling the compatibility. Specific examples include adhesive (OH group-containing) polyester, partially saponified vinyl acetate-vinyl chloride copolymer, polyamide, polyurethane, thermoplastic phenol resin, vinyl alcohol copolymer, acrylic acid copolymer, acrylamide copolymer. Examples include coalesced and maleic acid copolymers. In addition, it is natural to use a plasticizer in combination with this at appropriate times.

Of course, additives such as an antioxidant, an ultraviolet absorber or a plasticizer may be added to the recording layer of the present invention by a conventional method.

The addition amount of the crystalline organic molecules constituting the recording layer 3 or the second recording layer 7 to the matrix polymer can be added in the range of 5 to 50%.
Addition of ~ 40% is desirable. When the ratio of the crystalline organic molecules is higher than this, the binding force is weakened and it becomes difficult to uniformly coat the recording layer. On the other hand, when the ratio of the matrix polymer is high, the amount of crystalline organic molecules is small, which makes opacity difficult and deteriorates the contrast of recording.

The rewritable recording medium of the present invention can be recorded / erased by various light sources and lasers, and can be used as recording for low-cost optical disks, printers, and facsimiles. It can also be used as a method of reproducing a color image to be used. As described above, when light is used, the temperature increase rate ratio between the recording layer 3 and the second recording layer 7 can be adjusted by the depth of focus.

In the present invention, recording / erasing can be performed not only by a laser or a general light source but also by a thermal means such as a thermal head. However, when recording by thermal means, it is generally applied to single-color recording, but it goes without saying that multi-color recording is also possible by thermal means if it can correspond to the hue of the colored portion with a highly accurate recording pitch. .. In addition, a heating roller or the like may be used for heating in the initial state or the erased state.

The surface protective layer 6 in the present invention is not always necessary, but in general, it is often formed by a conventional method for the purpose of preventing scratches and dust on the recording layer 3, and the surface protective layer 6 is provided. The form is practical. Further, by providing the abrasion-resistant surface protective layer 6, for example, it is possible to construct a recording medium which has little deterioration over time and has high durability against repeated contact with a thermal head.

Next, the present invention will be described with reference to specific examples. (Example 1) 4 g of hydroxystearic acid as a crystalline organic molecule of a recording material, 0.1 g of a phenolic antioxidant as an additive, and a vinyl chloride-vinyl acetate copolymer having a partially saponified hydroxyl group as a transparent matrix polymer. 10 g and is dissolved in 100 ml of tetrahydrofuran,
Further, 7 g of red glass beads having an average particle diameter of 15 μm were dispersed as the coloring particles 4, and the substrate 1 having the reflective layer 2 shown in FIG. The recording layer 3 was formed by the gravure coating method. On the recording layer 3, a prepolymer of an ultraviolet curable acrylic resin was further coated as a wear-resistant surface protective layer 6 by a bar coating method to a thickness of 20 μm and then cured by irradiation with ultraviolet rays. The rewritable recording medium thus formed was written / erased by a semiconductor laser. The transparentization temperature range of this recording medium is about 70-9.
It was 0 ° C. Under this condition, energy was applied by a semiconductor laser to write at 100 ° C. and erase at 80 ° C. When the written opaque region and the erased transparent region were analyzed by X-ray diffraction, diffraction peaks were observed in both and it was found that they were fine crystals. These are respectively an opaque outer shell layer 5B in which the outer shell layer 5 of the crystalline organic molecule layer around the particles of the colored particles 4 is in a polycrystalline state and becomes opaque and in a light scattering state, and a transparent outer shell layer in a single crystal state. It was found to correspond to 5A. Further, the red recording by the glass beads showed a clear image quality. In the durability test, it could be repeated 600 times.

(Example 2) 3 g of behenic acid as a crystalline organic molecule of a recording material, 0.1 g of a phenolic antioxidant as an additive, and 2 g of an adhesive polyester (Byron Co., Ltd.) as a transparent matrix polymer. Polyurethane (5 g) was dissolved in tetrahydrofuran (100 ml), and black conductive black magnetite particles (4 g) having an average particle size of 20 μm were dispersed as colored particles to give 0.2 m shown in FIG.
A polyester polymer sheet substrate 1 of m having a thickness of 20 μm was formed as a recording layer 3 on a white reflective layer 2 having a white turbidity by a roll coating method. On the recording layer 3, a prepolymer of an ultraviolet-curable acrylic resin was further coated as a wear-resistant surface protective layer 6 by a bar coating method to a thickness of 25 μm and then irradiated with ultraviolet rays to be cured. The rewritable recording medium thus created is irradiated with a semiconductor laser to write / write.
It was erased. The transparency temperature range of this sheet is about 9
It was 0-110 degreeC. Under this condition, when energy was applied by a semiconductor laser and writing was performed at 120 ° C. and erasing was performed at 100 ° C., clear black recording was obtained. Further, the life characteristics were measured repeatedly, and it was able to withstand 480 repetitions.

Example 3 4 g of hydroxystearic acid as a crystalline organic molecule of a recording material, 0.1 g of a hindered phenolic antioxidant as an additive, and a vinyl chloride-vinyl acetate-acrylamide copolymer as a transparent matrix polymer. 6 g was dissolved in 100 ml of tetrahydrofuran to obtain a recording material solution. Using this recording material solution,
As shown in FIG. 3, 0.2 m of the substrate 1 having the black light absorbing layer 8 containing carbon black and having a thickness of 15 μm
A 10 μm-thick second recording layer 7 was formed on a m-thick polyester sheet by a blade coating method. On the other hand, 4 melamine resin particles each having an average particle size of 20 μm and colored with R, G and B were further added as colored particles 4 to the recording material solution.
g was dispersed, and a recording layer 3 having a thickness of 25 μm was formed on the second recording layer 7 of the substrate 1 by a blade coating method. An abrasion-resistant surface protective layer 6 is further formed on the recording layer 3.
As a prepolymer of an ultraviolet-curable acrylic resin was coated by a bar coating method to a thickness of 20 μm, the resin was irradiated with ultraviolet rays to be cured. When the rewritable recording medium thus formed was irradiated with light of a color image to perform writing, a clear color image was obtained. Further, after erasing, color image light was irradiated again to repeatedly form a color image. The transparentization temperature range of this recording medium is about 70.
Was ~ 90 ° C. Further, the life characteristics were measured repeatedly, and it was able to withstand 150 times of repetition.

(Example 4) Black light absorbing layer 8 having a thickness of 1
0.2 sprayed with 5 μm carbon black containing paint
A mm-thick polyester sheet is used as the substrate 1, and the same recording material as in Example 3 is used to form a recording layer 3 on the light absorption layer 8 in the same manner as in Example 3 with a thickness of 35 μm. Further, a prepolymer of an ultraviolet curable acrylic resin was coated as the surface protective layer 6 by a bar coating method to a thickness of 20 μm, and was then irradiated with ultraviolet rays to be cured. When the rewritable recording medium thus formed was irradiated with light of a color image in the same manner as in Example 3 to perform writing, a clear color image was obtained. Furthermore, after erasing,
The color image light was irradiated again to repeatedly form a color image. The transparentization temperature range of this recording medium is about 70-9.
It was 0 ° C. Further, the life characteristics were measured repeatedly, and it was possible to endure the repetition of 270 times.

In each of the above embodiments, an example of optical recording was shown, but thermal recording with a thermal head or the like was also possible. In particular, as shown in the above-mentioned examples, the effect of the surface protective layer 6 did not damage the thermal head, and good recording was possible.

Further, in the above embodiment, the case of monochromatic recording and color recording was illustrated, but it is needless to say that the same recording can be performed even in multicolor recording.

[0033]

As described above, the present invention is an excellent recording medium in which a recording layer containing crystalline organic molecules, a transparent matrix polymer, and colored particles having a crystal nucleation surface is formed on a substrate. A rewritable recording medium is provided.

The rewritable recording medium of the present invention is
When the colored particles are multicolored, color recording display can be performed. As described above, the present invention enables rewritable color recording with a simple configuration.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing the configuration of an embodiment of a rewritable recording medium of the present invention.

FIG. 2 (a) is an enlarged cross-sectional view of an essential part for explaining a crystalline organic molecular layer in a transparent state in the vicinity of a surface of a colored particle of an embodiment of a rewritable recording medium of the present invention. An enlarged cross-sectional view of an essential part for explaining an opaque crystalline organic molecular layer in the vicinity of the surface of the colored particles in one example of a possible recording medium

FIG. 3 is an enlarged sectional view of an essential part showing the configuration of another embodiment of the rewritable recording medium of the present invention.

FIG. 4 is an enlarged sectional view of an essential part showing the configuration of another embodiment of the rewritable recording medium of the present invention.

[Explanation of symbols]

 1 substrate 2 reflective film 3 recording layer 4 colored particles 4R red colored particles 4G green colored particles 4B blue colored particles 5 outer shell layer 5A transparent outer shell layer 5B opaque outer shell layer 6 surface protective layer 7 second recording layer 8 Light absorption layer

Claims (9)

[Claims] 1. A recording layer comprising a crystalline organic molecule, a transparent matrix polymer, and colored particles having at least the surface capable of forming crystal nuclei of the crystalline organic molecule on a substrate. Rewritable recording medium. 2. The rewritable recording medium according to claim 1, wherein the colored particles are spherical particles made of glass or polymer and having an average particle diameter of 1 to 100 μm. 3. The colored particles are a plurality of light transmissive particles each having a plurality of hues, one layer of the colored particles is arranged in a recording layer, and the transmitted light of the colored particles is absorbed under the recording layer. 3. The rewritable recording medium according to claim 1, further comprising a light absorbing layer. 4. The rewritable recording medium according to claim 3, wherein the colored particles are colored particles which are color-separated into three primary colors of red, green and blue. 5. A second recording layer containing crystalline organic molecules and a transparent matrix polymer is provided between the substrate and the light absorbing layer, according to claim 1, 3 or 4. Rewritable recording medium described. 6. The rewritable recording medium according to claim 1, wherein the crystalline organic molecule has a hydrogen bonding group, and the surface of the colored particle has a hydrogen bonding group. 7. The crystalline organic molecule has at least one of a carboxyl group and a hydroxyxyl group, and has 60 to 120.
7. The rewritable recording medium according to claim 6, wherein the rewritable recording medium comprises a molecule having a melting point at ° C. 8. A rewritable recording medium according to claim 1, further comprising a light reflection film provided between the substrate and the recording layer. 9. A crystalline organic molecule provided on a substrate,
A recording layer containing a transparent matrix polymer and a colored particle having at least a surface capable of forming crystal nuclei of the crystalline organic molecule, in the vicinity of the surface of the colored particle in the recording layer by a cooling process after melting in a low temperature mode. After making the crystalline organic molecule transparent, the colored particles are irradiated with light having an absorption wavelength, and the colored particles undergo a cooling process after melting in a high temperature mode accompanied by absorption of the absorbed light, and the coloring in the recording layer. A method for recording on a rewritable recording medium, characterized in that the crystalline organic molecule in the vicinity of the surface of a particle is made cloudy and the color of the colored particle is hidden and recorded.