JP2976398B2 - Reversible thermosensitive recording material and method for producing 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 material for recording and erasing by utilizing a reversible change in transparency of a thermosensitive layer depending on the temperature, and a method for producing the same.

[0002]

2. Description of the Related Art Many reversible thermosensitive recording materials have been proposed. For example, as a typical example, an organic low molecular weight substance such as a higher fatty acid is contained in a resin base material such as a postponed vinyl resin. A reversible thermosensitive recording material having a dispersed thermosensitive layer is known (JP-A-54-119377;
JP-A-55-154198, etc.). Image formation and erasing with this type of recording material utilize reversible changes in the transparency of the heat-sensitive layer with temperature, but the temperature at which the opaque portion is transparent is generally low, and there are some differences depending on the higher fatty acid used. Of about 65 to 72 ° C., and the width of the transparentizing temperature range is as narrow as 2 to 4 ° C. For this reason, use in a high-temperature environment is limited, and there is a problem in that at least a part of the entire opaque recording material is made transparent, or a temperature control when forming a transparent image on the entire opaque recording material is difficult. There was a practical problem.

In consideration of these points, the present inventors have previously described Japanese Patent Application Laid-Open Nos. 63-39378 and 63-13-13.
Japanese Patent Application Laid-Open No. 0380, JP-A-1-123788, etc., contain a certain kind of organic low-molecular substance (fatty acid ester, ether, thioether or plasticizer, etc.) and a substance which is easily eutectic with the organic low-molecular substance. It was shown that the temperature range for the transparency could be expanded. However, with the expansion of the application field of the reversible thermosensitive material, there has been a demand for further expanding the temperature range for the transparency. In addition, even if the invention in the material aspect as described above is reflected, the reversible thermosensitive material having a wide temperature range in which the temperature range for transparency changes depending on the manufacturing conditions of the thermosensitive layer, etc. Could not be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned disadvantages and drawbacks, and provides a reversible thermosensitive recording material having sufficient heating control and a method for producing the reversible thermosensitive recording material. is there.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a semiconductor device comprising the steps of:
In a reversible thermosensitive recording material provided with a heat-sensitive layer composed of an organic low-molecular substance whose transparency reversibly changes depending on temperature and a resin base material, the organic low-molecular substance was dispersed in the resin base material. A reversible thermosensitive recording material is provided, which has a phase separation structure in a state, and a structural period of phase separation of the thermosensitive layer is 1.5 μm or more. Further, in the method for producing a reversible thermosensitive recording material, a solution containing an organic low-molecular substance and a resin base material is coated on a support, a coating film is formed and dried, and a thermosensitive layer is formed. 90% solvent in the coating
The method for producing the reversible thermosensitive recording material is characterized in that after the above is evaporated, heat treatment is performed at 140 ° C. or higher.

The reversible thermosensitive recording material of the present invention utilizes the above-mentioned change in transparency (transparent state, cloudy opaque state), and the difference between this transparent state and cloudy opaque state is presumed as follows. . That is, (i) in the case of transparency, the particles of the organic low-molecular substance dispersed in the resin base material are composed of large particles of the organic low-molecular substance, and the light incident from one side is not scattered and is opposite. (Ii) In the case of cloudiness, the particles of the organic low-molecular substance are composed of polycrystals composed of fine crystals of the organic low-molecular substance, and the crystal axes of the individual crystals Is oriented in various directions, so that light incident from one side is refracted many times at the interface between the crystals of the organic low-molecular substance particles, and is scattered, so that it appears white.

In FIG. 1 (which shows a change in transparency due to heat), a heat-sensitive layer mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material is, for example, T
_At a room temperature of ₀ or less, it is cloudy and opaque. This is called temperature T ₂
When the temperature is returned to room temperature below T ₀ , the film remains transparent. This is from temperature T ₂ to T ₀
It is considered that the crystal grows from the fine polycrystalline state to the larger single crystal state through the semi-molten state of the organic low-molecular substance until the following. Upon further heating to T ₃ or more temperature becomes translucent state intermediate between the maximum transparency and the maximum opacity. Then, when the temperature is lowered, the state returns to the first cloudy and opaque state, which is again a transparent state. This after low-molecular organic material is melted at a temperature T ₃ or more, presumably because the polycrystals precipitated by being cooled. When this opaque state is heated to a temperature between T _{1 and} T ₂ and then cooled to room temperature, that is, a temperature equal to or lower than T ₀ , an intermediate state between transparent and opaque can be obtained. Also, by returning to room temperature After heating to be again T ₃ or more temperature which became clear at the normal temperature, the flow returns to cloudy opaque state again. That is, both opaque and transparent forms at room temperature and intermediate states thereof can be taken. Therefore, the heat-sensitive layer can be selectively heated by selectively applying heat to form a cloudy image on a transparent ground and a transparent image on a cloudy ground, and the change can be repeated many times. .

However, as described above, light scattering and light transmission are used depending on whether the recording / erasing of the reversible thermosensitive recording material is a fine polycrystalline state or a relatively large single crystal state in the crystalline state of the organic low molecular substance. Therefore, the crystal growth for causing light scattering and transmission and the effect thereof naturally depend on the phase separation structure between the organic low-molecular substance and the resin base material.

In describing the state of phase separation, the concept of the structural period becomes important. The structural period may be considered as a quantity representing the size of the phase separation structure. For example, FIG.
FIG. 2 shows a phase separation structure in which substance A forms a spherical domain in substance B as schematically shown in FIG.
Considering the cross section at the position of the dotted line in (a), FIG.
As shown in the above, the composition of the substance A and the substance B can be grasped in a periodically changed form. This period Λ is called a structural period. This structural period is not determined in any phase separation structure, but can be determined when the following factors are comprehensively satisfied, and is a meaningful numerical value. (1) The phase-separated structure has a certain degree of regularity and a characteristic structural period. (2) The volume ratio between the substance A and the substance B in the structure is not extremely large or small. (3) Substance A and substance B in the structure are clearly separated to some extent.

In the case of the reversible thermosensitive recording material according to the present invention,
The substance A may be considered as a low-molecular organic substance and the substance B may be considered as a resin base material, and these substances comprehensively satisfy the above factors (1), (2) and (3) in the heat-sensitive layer. In this case, the concept of the structural period becomes effective. However, the above (1),
It is not clear how much each of the factors (2) and (3) should be satisfied. A light scattering measurement method used for analyzing the structure of an organic polymer compound is effective as a method of capturing such a structural period. As shown in FIG. 3 (a), a method of measuring light scattering involves applying light from a light source to a sample and calculating the structural period from the scattering angle of the transmitted light. The relationship between the scattering angle and the structural period Λ Is given by equation (1). [Equation 1] Here, λ is the wavelength [μm] of the light source, D is the refractive index of the sample [−], and σ is the scattering angle [deg]. Generally, laser light is used as a light source for measurement, and He-N
e-lasers are most often used. (1),
When a sample satisfying the conditions (2) and (3) is applied to a light scattering measurement device, the scattered light shows a ring-shaped light intensity distribution as shown in FIG. When the scattered light intensity is plotted against the scattering angle, a curve having a peak value of the intensity at a certain angle as shown in FIG. 3B is shown. Angle θ at this peak value
The value obtained by substituting m into the above equation (1) becomes the structural period Δm unique to the sample.

In the reversible thermosensitive recording material according to the present invention, a specific method for measuring the structural period of the thermosensitive layer by a light scattering measurement method will be described as an example. As a light scattering measuring device, GP-7 (Optical Co., Ltd.) (light source He-
Ne laser wavelength λ = 0.6328 μm) was used.
The measurement sample needs to have a certain degree of light transmittance. Therefore, when the heat-sensitive layer is provided on an opaque support, the support must be removed to obtain a sample. However, when the heat-sensitive layer is provided on a transparent support, this is not the case.
The heat-sensitive layer is in the form of a film, and calculation of the scattering angle requires angle correction in consideration of the refractive index difference between the sample and air. The reason for this is that, as schematically shown in FIG. 4, the scattered light further refracts at the interface between the film and air, so that the apparent scattering angle θap becomes smaller than the true scattering angle θ.

Further, the sample according to the present invention changes to a cloudy, transparent, or translucent state depending on the temperature, and therefore, there is a problem in which state the light scattering measurement is performed. Since little scattering occurs in the transparent state, the light scattering measurement is performed in the cloudy or translucent state. In both cases, the shape of the light intensity distribution of scattering is slightly different, but the angle θ at the intensity peak value.
Since m hardly changes, the measurement should be performed in a state where measurement is easy.

If a colored sheet is arranged on the back of such a heat-sensitive element, an image of the color of the colored sheet on a white background or a white image on the background of the colored sheet can be formed.
Further, when projected by an OHP (overhead projector) or the like, the cloudy portion becomes a dark portion, the transparent portion transmits light, and becomes a bright portion on the screen.

To form and erase an image using such a reversible thermosensitive recording material, it is necessary to have two thermal heads for image formation and image erasing, or to change the applied energy conditions. It is effective to use a device having a single thermal head for forming an image and erasing an image. In the former case, the cost of the apparatus increases because two thermal heads are required, but if the energy application conditions for each thermal head are different and the reversible thermosensitive recording material is passed once, the formation and erasing of the image can be performed. Can do it. In the latter case, in order to form and erase an image with one thermal head, the condition for applying energy to the thermal head at one time when the thermal recording material passes is adjusted according to the part where the image is formed and the part to be erased. Although the operation is complicated, the operation is complicated, for example, the image is formed under different energy conditions by changing the thermal recording material in a small direction or by erasing the image on the thermal recording material once and then running the thermal recording material in the opposite direction again. Therefore, the equipment cost is reduced.

In order to prepare the reversible thermosensitive recording material according to the present invention, a solution in which two components of a resin base material and an organic low-molecular substance are dissolved is generally coated on a support such as a plastic sheet, a glass plate, or a metal plate. What is necessary is just to dry and form.

Further, the method for producing a thermosensitive layer having a phase separation structure having a structural period of 1.5 μm or more as in the present invention can be obtained by a solvent constitution, drying conditions and heat treatment conditions after drying. That is, the size of the structural cycle of the heat-sensitive layer can be controlled by the drying conditions. The weaker the drying strength, that is, the slower the drying, the larger the heat-sensitive layer having a large structural cycle. However, in order to obtain a heat-sensitive layer having a large phase-separated structure as in the present invention, if the drying strength is simply reduced, organic low-molecular solutes precipitate on the coating film surface after drying,
Often, this hinders the stacking of another layer. In order to suppress this precipitation, it is possible to take measures such as devising the solvent composition or precisely controlling the drying temperature, etc.However, it is possible to restrict the composition of the coating liquid or to devise the equipment. Had to be done.

Therefore, it has been found that the object of the present invention can be achieved by selecting drying conditions and heat treatment conditions subsequent to drying. That is, the solution is coated on a support to form a coating film, and after drying 90% or more of the solvent in the coating film by drying, heat treatment is performed at 140 ° C. or more, so that the structural period is 1.5 μm or more and A heat-sensitive layer without deposition of organic low-molecular substances on the coating film surface can be easily obtained. This provides a certain amount of drying strength that can suppress the deposition of organic low-molecular substances on the coating film surface, forms a heat-sensitive layer with a medium-sized structural cycle, and then heat-treats it to form a structural cycle. The heat-sensitive layer having a structural period of 1.5 μm or more without deposition of organic low-molecular substances on the surface because the state of the formed coating film surface does not change unless excessive heat is applied. Is obtained.

It is considered that the structural period is increased by the heat treatment due to the following mechanism. In other words, when the solvent of the coating film evaporates to some extent and shows a clear phase-separated structure, the resin base material and the organic low-molecular-weight substance do not become compatible with each other, and a force for separating works to increase the structural period. And However, when the temperature of the membrane is not sufficiently high, the force of separation cannot be overcome due to the high viscosity of the resin base material and lack of fluidity, but the viscosity of the resin base material increases as the temperature increases. This is due to an increase in the structural period due to a decrease in the fluidity.

Although the temperature of the heat treatment depends on the type of the resin base material and the type of the support, if it is too low, it takes time to increase the structural period, while if it is too high, the resin base material and the support may be deteriorated. Therefore, the temperature is preferably 140 ° C. or more and 250 ° C. or less. Means used for performing such heat treatment include a heater roll, a hot air heater, an infrared heater, and the like.

In the present invention, there is a method in which at least two or more kinds of organic solvents having different vapor pressures are used when dissolving the two components of the resin base material and the organic low-molecular substance. Various selections can be made depending on the type of the resin base material and the organic low-molecular substance, for example, tetrahydrofuran, tetrahydropyran,
Examples thereof include dioxane, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, and benzene.

In the present invention, the resin used as the resin base material of the heat-sensitive portion of the reversible thermosensitive recording material is preferably a resin which can form a film or sheet, has good transparency, and is mechanically stable. Examples of such a resin include polyvinyl chloride; vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, and vinyl chloride-acrylate copolymer. Vinylidene chloride copolymers such as polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer; polyester; polyamide; polyacrylate or polymethacrylate or acrylate -Methacrylate copolymers; silicone resins and the like. These may be used alone or as a mixture of two or more.

On the other hand, any organic low-molecular substance may be used as long as it changes from polycrystal to single crystal by heat in the heat-sensitive part (a substance which changes in the temperature range of T _{1 to} T ₃ shown in FIG. 1).
Generally, those having a melting point of about 30 to 200 ° C, preferably about 50 to 150 ° C are used. Such organic low molecular weight substances include alkanol; alkane diol; halogen alkanol or halogen alkane diol; alkylamine; alkane; alkene; alkyne; halogen alkane; halogen alkene; halogen alkyne; cycloalkane; cycloalkene; cycloalkyne; Unsaturated mono- or dicarboxylic acids or their esters, amides or ammonium salts; saturated or unsaturated halogen fatty acids or their esters, amides or ammonium salts; allylcarboxylic acids or their esters, amides or ammonium salts; Esters, amides or ammonium salts thereof; thioalcohols; thiocarboxylic acids or esters, amides or ammonium salts thereof; Carboxylic acid esters, and the like. These may be used alone or in combination of two or more. These compounds have 10 to 10 carbon atoms.
60, preferably 10 to 38, particularly preferably 10 to 30. The alcohol group in the ester may be saturated, may not be saturated, and may be halogen-substituted. In any case, the organic low molecular weight substance contains at least one kind of oxygen, nitrogen, sulfur and halogen in the molecule, for example, -OH, -COOH, -CONH, -COOR, -N
_{H, -NH 2, -S -,} - S-S -, - O-, is preferably a compound containing a halogen and the like.

More specifically, these compounds include lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, henicosanoic acid, tricosanoic acid, lignoceric acid, pentacosanoic acid, serotinic acid, montanic acid, melicic acid, stearic acid. Higher fatty acids such as acid, behenic acid, nonadecanoic acid, araginic acid and oleic acid; esters of higher fatty acids such as methyl stearate, tetradecyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate and dodecyl behenate; C ₁₆ H ₃₃ -OC ₁₆ H ₃₃ , C ₁₆ H ₃₃ -SC
_{16 H 33, C 18 H 37} -S-C 18 H 37, C 12 H 25 -S
_{-C 12 H 25, C 19 H} 39 -S-C 19 H 39, C 12 H 25
—S—S—C ₁₂ H ₂₅ , And ether or thioether. Among them, in the present invention, higher fatty acids, especially palmitic acid, heneicosanoic acid, tricosanoic acid, lignoceric acid, pentadecanoic acid,
Higher fatty acids having 16 or more carbon atoms, such as nonadecanoic acid, arachinic acid, stearic acid, and behenic acid, are preferred.
~ 24 higher fatty acids are more preferred.

Further, in order to widen the range of temperatures at which transparency can be obtained, the organic low-molecular substance described in this specification is appropriately combined, or such an organic low-molecular substance is combined with another material having a different melting point. I just need. These are disclosed in, for example, JP-A-63-39378 and JP-A-63-130380, and Japanese Patent Application Nos. 1-140109, 2-
Although disclosed in the specification such as No. 1363, the present invention is not limited thereto.

The ratio between the organic low-molecular substance and the resin base material in the heat-sensitive layer is preferably about 2: 1 to 1:16, more preferably 1: 2 to 1: 8 by weight. When the ratio of the resin base material is less than this, it becomes difficult to form an organic low-molecular substance in a film held in the resin base material. Becomes difficult.

The thickness of the heat-sensitive layer is preferably 1 to 30 μm,
2-20 μm is more preferred. If the heat-sensitive layer is too thick, heat distribution will occur in the heat-sensitive layer, making it difficult to achieve uniform transparency. On the other hand, if the heat-sensitive layer is too thin, the turbidity decreases and the contrast decreases. Further, the turbidity can be increased by increasing the amount of the organic low-molecular substance in the heat-sensitive layer.

In addition to the above components, additives such as a surfactant and a high boiling point solvent can be added to the heat-sensitive layer in order to facilitate formation of a transparent image. Specific examples of these additives are as follows. Examples of high boiling point solvents; tributyl phosphate, tri-2-phosphate
Ethylhexyl, triphenyl phosphate, tricresyl phosphate, butyl oleate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate , Dioctyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate,
Dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-2 azelate
-Ethylhexyl, dibutyl sebacate, di-2-ethylhexyl sebacate, diethylene glycol dibenzoate, triethylene glycol di-2-ethyl butyrate, methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, acetyl citric acid Tributyl.

Examples of surfactants and other additives: polyhydric alcohol higher fatty acid ester; polyhydric alcohol higher alkyl ether; polyhydric alcohol higher fatty acid ester, higher alcohol, higher alkylphenol, higher fatty acid higher alkylamine, higher fatty acid amide Lower olefin oxide adducts of fats and oils or polypropylene glycol; acetylene glycol; Na, Ca, Ba or Mg salts of higher alkylbenzene sulfonic acids; higher fatty acids, aromatic carboxylic acids, higher fatty acid sulfonic acids, aromatic sulfonic acids, monoesters of sulfuric acid Or Ca, Ba or Mg salts of phosphoric acid mono- or di-esters; low sulfated oils; poly long chain alkyl acrylates; acrylic oligomers; poly long chain alkyl methacrylates; Chromatography copolymers; styrene-maleic anhydride copolymer; olefin-maleic anhydride copolymer.

In the present invention, as the support of the reversible thermosensitive recording material, as described above, a plastic film,
A glass plate, a metal plate, or the like is used. In order to improve the image contrast of the recording material, a light reflection layer can be provided on the back surface of the recording layer. In this case, high contrast can be obtained even if the thickness of the recording layer is reduced. Specific examples include vapor deposition of Al, Ni, Sn, Au, Ag, and the like (described in JP-A-64-14079). When the support is made of a material having poor adhesion to a resin, such as an Al vapor-deposited layer, an adhesive layer may be provided between the support and the heat-sensitive layer (JP-A-3-7377). Alternatively, a method of providing low refraction of air or the like between the heat-sensitive layer and the coloring layer or the light reflecting layer may be used to improve the contrast.

Further, a protective layer may be provided on the heat-sensitive portion of the present invention in order to prevent the surface from being deformed by the heat and pressure of the heating means by a writing method such as a thermal head and the transparency of the transparent portion being reduced. good. A protective layer (thickness of 0. 0) laminated on the heat sensitive part.
Materials of silicone rubber, silicone resin (described in JP-A-63-221087), and polysiloxane graft polymer (JP-A-63-210 μm)
317385), an ultraviolet curable resin or an electron beam curable resin (described in JP-A-2-566).
Further, the surface may be roughened by a method such as adding an inorganic or organic filler to the protective layer in order to prevent dust, dirt and the like from adhering to the thermal head (Japanese Patent Laid-Open No. 4-8).
No. 5077). In any case, a solvent is used at the time of coating, and it is preferable that the solvent does not easily dissolve the resin of the heat-sensitive part and the organic low-molecular substance. Examples of the solvent that hardly dissolves the resin and the organic low-molecular substance in the heat-sensitive portion include n-hexane, methyl alcohol, ethyl alcohol, and isopropyl alcohol, and an alcohol-based solvent is particularly desirable in terms of cost.

Further, an intermediate layer can be provided between the protective layer and the heat-sensitive layer in order to protect the heat-sensitive layer from a solvent, a monomer component, and the like of the protective layer-forming solution (Japanese Patent Laid-Open No. 1-1378).
No. Gazette). As the material of the intermediate layer, the following thermosetting resins and thermoreversible resins can be used in addition to those listed as the resin base material in the thermosensitive layer. That is, specific examples include polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl butyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide, and the like. The thickness of the intermediate layer varies depending on the application, but is preferably about 0.1 to 2 μm. Below this,
The protective effect is reduced, and above this, the thermal sensitivity is reduced. Furthermore, it is also possible to provide a magnetic recording layer and use it as a card (Japanese Utility Model Laid-Open No. 2-3876, Japanese Unexamined Patent Publication No. 3-130).
188).

[0032]

According to the present invention, a reversible thermosensitive recording material having a sufficient heating control can be obtained by setting the structural period of the phase separation structure of the thermosensitive layer to 1.5 μm or more. Although the reason for this is not clear, as described above, the magnitude of the interaction between the organic low-molecular substance and the resin base material, which affects the crystal state of the organic low-molecular substance, varies depending on the structural period of the phase separation. It is thought to be due to this. Either one or both of the following two factors must be satisfied in order for the temperature range to be transparent to be widened. (1) In a domain, a crystal growth change from a fine polycrystalline state in a cloudy state to a larger single crystal state in a transparent state occurs at a lower temperature. (2) In the domain, the temperature at which the organic low-molecular substance is melted and becomes semi-opaque becomes higher. The above factors (1) and (2) are problems when the crystal state of the organic low-molecular substance in the domain changes, and it is considered that the interaction with the resin base material influences the change. . Further, the magnitude of the influence changes with the structural period, and it is considered that a sufficiently wide transparency temperature range is provided when the structural period is 1.5 μm or more.

In the present invention, the factor (1) is more important than the factor (2) in the degree of contribution to the transparency temperature range. For factor (1), the interaction can be interpreted as follows. That is, the interaction between the organic low-molecular substance and the resin base material acts as a force that prevents the formation of very fine crystals as a result, and the magnitude of this force increases as the structural period decreases. Conversely, if it is assumed that a very large polycrystal can be easily formed when the structural period is large, the domain in the cloudy state when the structural period is large is formed as a set of very fine crystals, while when the structural period is small. The domain in the cloudy state is formed as a set of crystals slightly larger than this. Since the melting point of the crystal decreases as the size of the crystal decreases, it is considered that a change from a polycrystalline state to a single crystal state occurs at a lower temperature when the structural period is large, which is a collection of smaller fine crystals.

[0034]

EXAMPLES All parts and percentages herein are by weight. EXAMPLE 1 Behenic acid 6 parts Eicosane diacid 4 parts Vinyl chloride-vinyl acetate copolymer 40 parts (Denka vinyl # 1000GK, manufactured by Denki Kagaku Kogyo KK) Diisodecyl phthalate 3 parts Tetrahydrofuran on a transparent polyester film about 50 μm thick A solution consisting of 148 parts of toluene and 49 parts of a solution was applied with a wire bar, dried in a hot air drier at 100 ° C. for 60 seconds, quickly put into an infrared heater, and heat-treated for 30 seconds. The temperature at this time was 160 ° C.
190 ° C. In this manner, a recording layer having a thickness of 15 μm is provided, and further thereon, 10 parts of a 75% butyl acetate solution of a urethane acrylate-based ultraviolet curable resin (manufactured by Dainippon Ink and Chemicals, Inc., Unidic C7-157) 10 parts isopropyl alcohol 10 Part of the solution is applied with a wire bar, dried in a hot air drier at 100 ° C. for 60 seconds, and cured with an ultraviolet lamp of 80 w / cm to provide an overcoat phase having a thickness of about 2 μm to prepare a reversible thermosensitive recording material. did.

Example 2 A reversible thermosensitive material was prepared in the same manner as in Example 1 except that the heat treatment time was changed to 60 seconds.

Example 3 A reversible thermosensitive recording material was prepared in the same manner as in Example 1 except that the thickness of the recording layer was changed to 10 μm.

Example 4 A reversible thermosensitive recording material was prepared in the same manner as in Example 2 except that the thickness of the recording layer was changed to 10 μm.

Comparative Example 1 The same solution as in Example 1 was applied on a transparent polyester film having a thickness of about 50 μm with a wire bar, and dried with a hot air drier at 100 ° C. for 90 seconds to provide a heat-sensitive layer having a thickness of 15 μm. Further, an overcoat layer similar to that of the example was further provided thereon to prepare a reversible thermosensitive recording material.

Comparative Example 2 In the same manner as in Comparative Example 1, a reversible thermosensitive material provided with a recording layer having a thickness of 10 μm was prepared.

Comparative Example 3 A reversible thermosensitive recording material was prepared in the same manner as in Comparative Example 2 except that the drying temperature was changed to 110 ° C.

Comparative Example 4 A reversible thermosensitive recording material was prepared in the same manner as in Comparative Example 1 except that the drying temperature was changed to 70 ° C.

The structure cycle of the reversible thermosensitive recording material prepared as described above was measured by the light scattering measurement method described above.
The measurement was performed in an intermediate state (85 ° C.) between cloudy and transparent. The structural period was calculated with the refractive index D set to 1.5. FIG. 5 shows the relationship between the scattering angle and the intensity in Example 1 and Comparative Example 1.
Next, each of the prepared reversible thermosensitive recording materials was heated by a thermal gradient tester (Type H-100, manufactured by Toyo Seiki Seisaku-sho, Ltd.) in a temperature range of 50 to 118 ° C. every 2 ° C. The image density of the warm part was measured. The image density was measured using a Macbeth reflection densitometer RD-914. At that time, the density measurement was performed with black (OD 1.9) printed on the back side. The clearing temperature range is O.D. D = [(most transparent density−most opaque density) × 0.9 + most opaque density]
S. The density was read from the graph, and the difference was obtained.
However, Comparative Example 4 was excluded from the evaluation because the organic low molecular weight substance was deposited on the surface. Table 1 summarizes the above results. FIG. 6 shows the relationship between the structural period and the transparency temperature range. FIG. 6 shows that for each of the film thicknesses of 15 μm and 10 μm, the transparency temperature width increases with the structural period. Further, the reversible thermosensitive recording material of the present invention has a larger structural period and a wider transparency temperature range than conventional ones.

[0043]

[Table 1]

[0044]

According to the reversible thermosensitive recording material of the present invention, since the structural period of the phase separation of the thermosensitive layer is 1.5 μm or more, the range of the transparency temperature range is wide, and the heating control in recording and erasing is easy. is there. Further, in the heat-sensitive layer formation of the present invention,
The above-mentioned reversible sensation is obtained by applying a coating solution for forming a heat-sensitive layer on a support, forming a coating film, evaporating 90% or more of the solvent in the coating film by drying, and then heat-treating to 140 ° C. or more. Thermal recording materials can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in transparency of a reversible thermosensitive recording material according to the present invention due to heat.

FIG. 2A is a diagram schematically illustrating a phase separation structure. (B) is a diagram schematically showing the relationship between the phase separation structure and the structural period.

FIG. 3 is a diagram schematically illustrating the concept of light scattering measurement.

FIG. 4 is a diagram schematically showing a relationship between an apparent scattering angle and a true scattering angle.

FIG. 5 is a diagram showing the results of light scattering measurement of Example 1 and Comparative Example 1.

FIG. 6 is a diagram showing a relationship between a structural period and a transparentization temperature range.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsutomu Kagawa 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (56) References JP-A-54-119377 (JP, A) JP-A Sho 55-154198 (JP, A) (58) Fields studied (Int. Cl. ⁶ , DB name) B41M 5/36

Claims (3)

(57) [Claims] 1. A reversible thermosensitive recording material comprising a support and a reversible thermosensitive layer comprising a thermosensitive layer comprising a low-molecular organic substance whose transparency changes reversibly depending on temperature and a resin base material. Wherein the organic low-molecular substance has a phase separation structure in a state of being dispersed in the resin base material, and the structural cycle of phase separation of the heat-sensitive layer is 1.5 μm or more. Recording material. 2. The method according to claim 1, further comprising providing a magnetic recording layer.
The reversible thermosensitive recording material according to claim 1. 3. A solution containing the low-molecular organic material and the resin base material coated on a support, and then dried to form a coating film, reversible sense of consisting to form a heat-sensitive layer according to claim 1 or 2, wherein 3. The method for producing a reversible thermosensitive recording material according to claim 1 or 2 , wherein in the method for producing a thermal material, after evaporating 90% or more of the solvent in the coating film, heat treatment is performed at 140 ° C or more.