JP2598841B2 - Reversible thermosensitive recording material and recording medium using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive recording material capable of reversibly recording and erasing by heating and a multicolor recording medium using the same. More specifically, a memory card with a rewritable display function used as a prepaid card such as a commuter pass, a ticket, a coupon, and an IC
The present invention relates to a reversible thermosensitive recording material useful for cards, facsimile recording paper, and the like, and a multicolor recording medium using the same.

[0002]

2. Description of the Related Art Conventional reversible thermosensitive recording materials include a thermosensitive dye-based recording material which reversibly develops and decolors with a combination of a leuco dye, a developer and a decolorant, and an organic crystal in a matrix polymer. Using the melting / solidification behavior of particles, the phase-change type reversible thermosensitive recording material that uses the change in transparency of the particles depending on the coagulation conditions, and the thermal behavior of its molecular arrangement using a liquid crystal polymer (mainly cholesteric liquid crystal). A method of changing transparency by using the same has been proposed.

On the other hand, in the field of printing and recording materials, coating techniques using microcapsules are generally widely known and applied to many printing and recording sheets.

A phase change type thermosensitive recording material utilizing the melting and coagulation behavior of organic crystal particles in a matrix polymer and utilizing the fact that the transparency of the particles changes depending on the coagulation conditions is known. Japanese Patent Application Laid-Open No. 54-119377 and the like have been proposed as a device which solidifies again and causes a difference in the transparency of a solidified form (polycrystalline state, single crystal state, amorphous state, etc.) depending on the conditions and records. This heat-sensitive recording material is constituted by a combination of a matrix polymer and the following fusible organic molecules, and can constitute an extremely wide variety of recording materials. The fusible organic molecules disclosed herein include aliphatic and aromatic alcohols, carboxylic acids, amines, amides, and halides and sulfides thereof. On the other hand, as the matrix polymer, polyester, polyamide, polyacrylic acid,
Common polymers such as styrene, silicone, polyvinyl chloride, polyvinylidene chloride, and polyacrylonitrile are disclosed. A recording material obtained by improving this and further adding carbon black and an antioxidant is disclosed in
Nos. 82087 and 57-82088.

[0005]

However, although fusible organic molecules and matrix polymers are disclosed here,
The compatibility and dispersibility of each other are not devised, and there is a problem that it is difficult to appropriately disperse the organic crystal particles, and it is not possible to obtain high-density recording with excellent recording resolution.

In order to solve the problems of the prior art, the first object of the present invention is to obtain a reversible thermosensitive recording material system having excellent recording characteristics by microencapsulating organic crystalline molecules with a transparent matrix polymer. The purpose is.

A second object of the present invention is to provide a recording medium which can be widely used for a card with a display function, a facsimile paper, and the like by making a recording sheet capable of multicolor recording using the microencapsulated thermosensitive recording material. I do.

[0008]

In order to achieve the above-mentioned first object, the present invention provides a method for producing a liquid crystal display device, comprising the steps of:
Coated with micro A and microencapsulated
In the coating portion, the organic crystal particles and the transparent matrix
It is compatible with cuppolymer A, which is further composed of a thin film dispersed in a separate transparent matrix polymer B.
A heat energy is applied to the thin film from the outside to melt and solidify the organic crystal particles, and reversibly change the transparency for recording.

An excellent recording material system can be constituted by the fact that both the organic crystal particles and the transparent matrix polymer A have a hydrogen bonding group. Organic crystal particles having a hydrogen bonding group are composed of molecules having at least one of a carboxyl group and a hydroxyxyl group and having a melting point at 60 to 120 ° C., and a transparent matrix polymer having a hydrogen bonding group is a urea resin, an epoxy resin, a melamine. Resin, OH group-containing polyester, partially saponified vinyl acetate-vinyl chloride copolymer, polyamide, polyurethane, thermoplastic phenolic resin, vinyl alcohol copolymer, acrylic acid copolymer, acrylamide copolymer, maleic acid copolymer It is desirable to be the selected type.

Further, the organic crystal particles are composed of molecules having both a hydrogen bonding group and an alkyl or alkylene group having 10 or more carbon atoms, and the transparent matrix polymer A has a repeating unit having an alkylene component having 10 or more carbon atoms in the repeating unit. A configuration using a molecule can also be adopted.

In order to achieve the second object, according to the present invention, coloring is performed by adding a dye to the transparent matrix polymer A. Forming a reversible thermosensitive recording material including microcapsules of a plurality of colors on a polymer sheet on which a reflective film is formed,
Further, a multi-color recording medium is formed by forming a surface coat layer.

[0012]

According to the reversible thermosensitive recording material of the present invention, the organic crystal particles are coated with the transparent matrix polymer A as described above.
And microencapsulated. Since the organic crystal particles and the transparent matrix polymer A are compatible with each other, they exhibit highly reliable melting and solidifying properties due to mutual interaction.
The combination in which the compatibility is too large to dissolve the organic crystal particles in a large amount tends to be unsuitable for the present invention.

According to the present invention, the organic crystal particles and the transparent matrix polymer A are both constituted by a combination of materials having a hydrogen bonding group, and have a hydroxyl group or a carboxyl group as a hydrogen bonding group and have an melting point at 60 to 120 ° C. The crystallization behavior of the crystal particles in the capsule of the matrix polymer A proceeds through the hydrogen bonding interface with the transparent matrix polymer A. Therefore, the number and nature of the hydrogen bonding groups at the interface between the crystal particles and the polymer determine this behavior. In this configuration, since the organic crystal particles and the transparent matrix polymer A are both composed of a material having an appropriate compatibility having a hydrogen bond, the fine crystal particles are successfully precipitated in the capsule, and a highly reliable and excellent crystallization behavior is obtained. No cracking or breakage of the microcapsules occurs.

On the other hand, the organic crystal particles are composed of molecules having both a hydrogen bonding group and an alkyl or alkylene group having 10 or more carbon atoms, and the transparent matrix polymer A is a polymer having an alkylene component having 10 or more carbon atoms in a repeating unit. In a configuration consisting of a capsule, the core and the coating of the capsules have the affinity of the alkylenes acting to create micelles of the opposite type as in the case of the hydrogen bonding system.

Further, when the reversible thermosensitive recording material of the present invention containing a plurality of types of microcapsules colored in various colors is formed on a polymer sheet having a reflective film formed thereon, and a surface coat layer is further provided, the heat reversible recording material is obtained. A multicolor recording medium in which light is scattered into various colors by opacity by writing can be configured.

[0016]

FIG. 1 shows the structure of a reversible thermosensitive recording material of the present invention. The microcapsules of the organic crystal particles 1 having the coating layer of the transparent matrix polymer A2 are transparent matrix polymer B3.
Distributed. FIG. 2A shows a transparent state and the organic crystal particles 1a are single crystal particles. On the other hand, FIG. 2B shows an opaque state and the organic crystal particles 1b are polycrystalline particles.

As shown in FIG. 2, the organic crystal particles 1 take two states, a transparent single crystal state 1a and an opaque polycrystalline state 1b (light scattering state) at room temperature, which correspond to erasure and recording, respectively. A wider transparent temperature range facilitates recording control.

It is desirable that both the organic crystal particles and the transparent matrix polymer A used in the present invention are composed of molecules having a hydrogen bonding group.

As the organic crystal particles, molecules having at least one of a carboxyl group and a hydroxyxyl group as a hydrogen bonding group and having a melting point at 60 to 120 ° C. are used. Compounds belonging to this group include alkanols, alkanediols, alkylamines, alkylenediamines, mono- or dicarboxylic acids, amides, and sulfides and halides thereof. These compounds are
They are used alone or in combination of two or more. The number of carbon atoms is preferably from 10 to 30. Specific compounds include
Higher fatty acids include lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid,
Stearic acid, nonadecanoic acid, arachidic acid, behenic acid,
There are oleic acid and the like, and higher alcohols include hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, eicosanol, docosanol and the like.

These molecules are further co-crystallized or complexed with other higher alcohols, fatty acids, alkylamines, oxycarboxylic acids, dicarboxylic acids, diamines, alkylene glycols, etc. and have a melting point at 60-120 ° C. Organic molecular crystal particles can also be formed.

On the other hand, generally, matrix polymers include polyester, polyacrylate, polyvinyl chloride,
There are vinyl chloride-vinyl acetate copolymer, cellulose acetate, polyvinyl butyral, polystyrene, styrene-butadiene copolymer and the like, and the matrix polymer A of the present invention is preferably a hydrogen-bonded group-containing transparent matrix polymer. Specific examples include urea resin, epoxy resin, melamine resin, adhesive (OH group-containing) polyester, partially saponified vinyl acetate-vinyl chloride copolymer, polyamide,
Suitable are polyurethane, thermoplastic phenolic resin, vinyl alcohol copolymer, acrylic acid copolymer, acrylamide copolymer, maleic acid copolymer and the like.

Any of these polymers can be used as the matrix polymer B for dispersing the microcapsules, and can be arbitrarily selected . Since the recording material is used in a thin film, considerable transparency is obtained. Also, this can be done in arbitrary be timely used in combination plasticizer.

On the other hand, the organic crystal particles are composed of a molecule having both a hydrogen bonding group and an alkyl or alkylene group having 10 or more carbon atoms, and the transparent matrix polymer A is a polymer having an alkylene component having 10 or more carbon atoms in a repeating unit. In a configuration consisting of a capsule, the core and the coating of the capsules have the affinity of the alkylenes acting to create micelles of the opposite type as in the case of the hydrogen bonding system. As the transparent matrix polymer A in this case, a styrene-butadiene copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylate copolymer, an olefin copolymer, or the like is suitable.

The addition amount of the microcapsules to the matrix polymer B depends on the size of the capsules and the thickness of the coating layer, but can be added in a range of about 10 to 70%, and the addition of 20 to 40% is more preferable. desirable. When the ratio of the microcapsules is more than this, the binding force is weakened, and it is difficult to form a uniform coating as a recording layer. Conversely, when the ratio of the matrix polymer B increases, the amount of microcapsules decreases, and the recording contrast deteriorates.

The inclusion of a crystal nucleating agent having a hydrogen bonding surface in the microcapsules of the present invention is very effective in improving the reliability of crystallization characteristics. It is also effective to include an antioxidant having active hydrogen.

Microcapsules are made using micelles formed by coacervation.
It is divided into aqueous and non-aqueous systems. In coacervation,
There are two types: simple coacervation by a combination of a polymer solution and a non-solvent or an electrolyte; and complex coacervation with electrical phase separation represented by a combination of a polycation and a polyanion. Specific manufacturing methods include chemical manufacturing methods such as interfacial polymerization, in situ polymerization, and interfacial hardening coating with the addition of a hardener, methods using phase separation, spray drying, and fluid coating. There is a physical manufacturing method. All of these production methods can be used in the present invention.

Further, the reversible thermosensitive recording material of the present invention containing a plurality of types of microcapsules 5 colored in various colors is shown in FIG.
By forming on the polymer sheet 4 on which the reflective film 8 is formed as described above and further applying the surface coat layer 7, a multicolor recording sheet that is scattered to various colors by opacity by thermal writing can be formed. Can be. A recording medium using this reversible thermosensitive recording material can be written / erased in a heat mode not only by a thermal head but also by a laser. In some cases, a heat roller is used for erasing. That is, if the reversible thermosensitive recording material of the present invention is formed on a polymer substrate on which a reflective film is formed, and further a surface coat layer is formed, clear recording with very high resolution can be easily performed. An excellent high-density optical recording medium to be erased is obtained. This can be used as a rewritable and low-cost optical disk. Further, when recording / erasing is performed with a thermal head, if a wear-resistant surface coat layer is provided, a recording medium with little deterioration over time even with contact with the thermal head can be constructed with high repetitive durability. . Next, the present invention will be described using examples.

Example 1 As a recording material, an average particle diameter of 35 μm having stearic acid as organic crystal particles 1 (core) and a urea resin coating layer 2 was used.
Was dispersed and dissolved in 100 ml of tetrahydrofuran to form a 0.2 mm-thick aluminum vapor-deposited reflection layer 8 shown in FIG.
1 as a recording layer 6 on the polyester polymer sheet 4
It was formed with a thickness of 3 μm. The recording layer 6 was further coated with a UV-curable acrylic resin prepolymer of 15 μm as a wear-resistant surface coat layer 7 and then cured by irradiation with ultraviolet light. Writing and erasing were performed on the reversible thermosensitive recording sheet thus formed by a thermosensitive head. The clearing temperature range of this sheet was about 75 to 100 ° C. Under these conditions, energy was applied by a thermal head to write at 110 ° C. and erase at 85 ° C. These records respectively show the opaque polycrystalline state 1b of the organic crystal particles 1.
(Light scattering state) and a transparent single crystal state 1a. When observed with a scanning electron microscope, clean microcapsules were observed.

Example 2 As recording materials, 4.5 g of microcapsules having an average particle diameter of 20 μm and organic layer 1 made of behenic acid and a trace amount of a phenolic antioxidant, and crosslinked polyurethane as coating layer 2 were used. 6 g of alcohol was dispersed and dissolved in 100 ml of ethyl alcohol, and a recording layer 6 having a thickness of 20 μm was formed on a 0.2-mm polyester polymer sheet 4 on which an aluminum deposited reflective layer 8 was formed as shown in FIG. The recording layer 6 was further coated with a UV-curable acrylic resin prepolymer having a thickness of 25 μm as a wear-resistant surface coat layer 7 and then cured by irradiating ultraviolet rays. Writing and erasing were performed on the reversible thermosensitive recording sheet thus formed by a thermosensitive head. The clearing temperature range of this sheet was about 95 to 120 ° C. Under these conditions, when energy was applied by a thermal head to write at 125 ° C. and erased at 110 ° C., clear recording characteristics were obtained. When the life characteristics were further measured repeatedly, it was able to withstand 740 repetitions.

Example 3 As recording materials, microcapsules of three colors each having stearyl alcohol as organic crystal particles 1 (core) and a coating layer 2 of an ethylene-vinyl acetate copolymer colored with a dye were used.
5 g and 5 g of polyvinyl butyral were dissolved in 100 ml of ethyl alcohol to form a reflective layer 8 having a golden surface.
On a 1 mm thick sheet 4 of 0.2 mm rigid polyvinyl chloride,
The recording layer 6 was formed with a thickness of 25 μm. The recording layer 6 was further coated with a UV-curable acrylic resin prepolymer of 10 μm as a surface coat layer 4 and then cured by irradiating UV rays. Writing and erasing were performed on the reversible thermosensitive recording sheet thus formed using a semiconductor laser. Separately, the clearing temperature range of this sheet measured by a thermal head was about 70 to 90 ° C.

The recording sheet was cut to further form a magnetic recording layer, thereby obtaining a recording card with a display function.

[0032]

As described above, according to the present invention, the organic crystal particles
Since the reversible thermosensitive recording material is covered with the transparent matrix polymer A, microencapsulated, and further dispersed in the matrix polymer B, the organic crystal particles and the matrix polymer have good compatibility and can interact with each other. Has reliable melting and solidification characteristics. In particular, the crystallization behavior of microcapsules consisting of organic crystal particles having both hydrogen bonds and matrix polymer A proceeds through the hydrogen bonding interface with the matrix polymer, and the number and properties of the hydrogen bonding groups at the interface determine this behavior. And exhibit stable and stable crystallization characteristics. Therefore, it is possible to obtain an excellent heat-sensitive recording material without cracking or breaking of the capsule.

Further, in a recording medium in which the reversible thermosensitive recording material of the present invention containing a plurality of types of microcapsules colored in various colors is formed on a polymer sheet on which a reflective film is formed, various opacity due to thermal writing is obtained. A multicolor recording medium that is scattered by the light of the above color can be formed. Thus, the present invention is of great industrial value.

[Brief description of the drawings]

FIG. 1 is a view showing a configuration of a reversible thermosensitive recording material according to the present invention.

FIG. 2 is a view showing a state of organic crystal particles in a reversible thermosensitive recording material of the present invention. (A) is a transparent state and the organic crystal particles 1a are single crystal particles. On the other hand, (b) is an opaque state and the organic crystal particles 1b are polycrystalline particles.

FIG. 3 is a view showing one embodiment of a recording medium using a reversible thermosensitive recording material according to the present invention.

[Explanation of symbols]

Reference Signs List 1 Organic crystal particles (a: transparent single crystal particles, b: opaque polycrystalline particles) 2 Transparent matrix polymer A 3 Transparent matrix polymer B 4 Polymer sheet 5 Microcapsule 6 Recording layer 7 Surface coat layer 8 Reflective layer

Claims (7)

(57) [Claims] 1. The method according to claim 1, wherein the organic crystal particles form a transparent matrix polymer A.
Therefore, it is coated and microencapsulated,
In the part, the organic crystal particles and the transparent matrix poly
The organic crystal particles are compatible with the matrix A, and further comprise a thin film dispersed in a separate transparent matrix polymer B. The organic crystal particles are melted and solidified by external heat energy, and the transparency is reversibly changed. Reversible thermosensitive recording material for recording. 2. Organic crystal particles and transparent matrix polymer A
The reversible thermosensitive recording material according to claim 1, wherein both have a hydrogen bonding group. 3. An organic crystal particle having a hydrogen bonding group is composed of a molecule having at least one of a carboxyl group and a hydroxyxyl group and having a melting point at 60 to 120 ° C., and the hydrogen bonding group-containing transparent matrix polymer is a urea resin. , Epoxy resin, melamine resin, OH group-containing polyester, partially saponified vinyl acetate-vinyl chloride copolymer, polyamide,
The reversible thermosensitive recording material according to claim 2, wherein the material is one selected from polyurethane, thermoplastic phenol resin, vinyl alcohol copolymer, acrylic acid copolymer, acrylamide copolymer, and maleic acid copolymer. 4. A polymer in which organic crystal particles are composed of a molecule having both a hydrogen bonding group and an alkyl or alkylene group having 10 or more carbon atoms, and wherein the transparent matrix polymer A has an alkylene component having 10 or more carbon atoms in a repeating unit. 2. The reversible thermosensitive recording material according to claim 1, comprising: 5. The reversible thermosensitive recording material according to claim 1, wherein the microcapsules contain a hydrogen bonding nucleating agent or an antioxidant having active hydrogen. 6. The reversible thermosensitive recording material according to claim 1, wherein the transparent matrix polymer A contains a dye and performs color recording. 7. A reversible thermosensitive recording material containing a dye according to claim 6, which is a reversible thermosensitive recording material of a plurality of colors, is formed on a polymer sheet on which a reflective film is formed, and further comprises a surface coat layer. Recording medium on which multi-color recording is performed.