JPH05297677A - Method and device for forming reversible thermosensitive recording image - Google Patents

Abstract

PURPOSE:To improve the durability of a reversible thermosensitive layer by allowing image-like toner or carrier to generate heat, heating the thermosensitive layer and forming an image. CONSTITUTION:In the case that the recording image is obtained on a thermosensitive display body 8, an electrostatic charge image is formed by uniformly and electrostatically charging the surface of a photosensitive body 1, first. Besides, the electrostatic charge image is formed by exposing the image and developed. By bringing the display body 8 into contact with the surface of the body 1 after the developing and simultaneously irradiating it with light from the back surface side of the display body 8, the toner or the carrier is allowed to generate heat and the thermosensitive layer of the display body 8 is heated by the heat. Then, the image is displayed. In such a case, the display body 8 is obtained by forming a thermosensitive recording layer on a supporting body (substrate) and moved so that the thermosensitive recording layer is positioned on the body 1 side. The quality of the material of the supporting body is not specially restricted. However, a polyvinyl chloride film, a polyethylen film, glass or the like is mentioned. A light source is not also restricted. It is good that the light source having such wavelength that the toner or the like generates heat by receiving the light thereof. Therefore, the life of the thermosensitive display body is prolonged without receiving damage caused by heat or pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for forming a reversible thermosensitive recording image, and more particularly, it can be applied to a display portion of a functional card such as an IC card, an optical card, a magnetic card, and an overhead projector (OHP). The present invention relates to a reversible thermosensitive recording image forming method and apparatus that can be widely used for displays such as a static projector and a video projector.

[0002]

2. Description of the Related Art In recent years, reversible heat-sensitive materials have attracted attention because they enable temporary image formation and can erase images when they are no longer needed. As a typical example thereof, a reversible thermosensitive recording material in which an organic low molecular weight substance such as a higher fatty acid is dispersed in a resin base material such as a vinyl chloride resin is known (Japanese Patent Laid-Open No. 54-119377, JP-A-54-119377). Publications such as Kaisho 55-154198). However, since these are printed by a thermal head, there are problems such as uneven printing and destruction of the substrate on a hard substrate such as a concave-convex substrate or a vinyl chloride card or conversely a soft substrate, and further, it does not pass through the thermal head and can be used. There were restrictions on the board. Further, due to heat and pressure from the thermal head, there is a problem in durability of the recording layer itself, and measures such as providing an intermediate layer and a protective layer on the recording layer have been taken.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned defects and to provide a reversible heat-sensitive layer (hereinafter simply referred to as "heat-sensitive layer") on either a hard or soft substrate (preferably a transparent substrate). (Sometimes referred to as "thermosensitive recording layer"), a method in which recording and erasing can be repeated many times on the display unit composed of the reversible thermosensitive layer without any inconvenience, And an apparatus useful for carrying out the method. Another object of the present invention is to provide a method and an apparatus capable of forming an image by significantly improving the durability of the reversible thermosensitive layer.

[0004]

The method for forming a reversible thermosensitive recording image according to the present invention comprises forming an electrostatic charge image on an electrophotographic photosensitive member and developing it with a carrier containing or coated with a toner or a light absorbing substance. After this, the image-like toner or carrier is brought into contact with the heat-sensitive layer of a heat-sensitive display having a heat-sensitive layer whose transparency or color reversibly changes depending on the temperature on a transparent support, and is transparent. Light is applied from the support side to heat the image-like toner or carrier, and the heat is used to heat the heat-sensitive layer to display an image.

The reversible thermosensitive recording image forming apparatus of the present invention comprises a photoconductor, a charging section, an exposing section, a developing section, a transferring section, a light source section, a cleaner section, a discharging section, a paper feeding section and a fixing section. When this is used as an electrophotographic copying apparatus, all but the above-mentioned light source section is used, and when it is used as a reversible thermal image recording / display apparatus, the developing section uses only a carrier and It is characterized in that it can be used in both an electrophotographic copying apparatus and a thermal image display apparatus by using everything except the transfer section and the fixing section.

The present inventors have studied from various angles in order to achieve the above-mentioned object, and as a result, damage the member by organically associating the electrophotographic method with a member exhibiting specific properties. It was confirmed that the recording and erasing can be repeatedly performed there, and the apparatus itself can be used as a normal electrophotographic copying machine. The present invention has been made based on such findings.

The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 shows the outline of the main part of the device of the present invention. In the figure, 1 is a drum-shaped photosensitive member, 2 is a charging unit, 3
Is an exposure unit, 4 is a developing unit, 5 is a cleaner unit, 6 is a charge eliminating unit, 7 is a paper feed roller (paper feed unit), 8 is a thermosensitive display, and 9 is a light source. Note that the configuration shown in FIG. 1 assumes that an image is formed on the thermosensitive display 8, and therefore when this apparatus is used as an electrophotographic copying machine for forming an image of toner on plain paper or the like. Instead of using the thermal display 8 (necessarily not using the light source 9), plain paper or the like is used, and conversely, it is necessary to provide a transfer section and a fixing section not shown.

Now, in order to obtain a recorded image on the thermosensitive display 8 using the apparatus shown in FIG. 1, first, the surface of the photoconductor 1 is uniformly charged and imagewise exposed to form an electrostatic charge image. Form. Then, the electrostatic image is developed. The development here may be performed with toner or carrier. However, for the carrier development here, it is advantageous to use a carrier having a light-absorbing property or one having a light-absorbing substance attached to the surface of the carrier.

At the same time when the photosensitive display 8 is brought into contact with the surface of the photosensitive body 1 after development, light is irradiated from the back side of the thermal display 8 to heat the toner or carrier, and the heat causes the thermal display 8 to move. The thermosensitive layer is heated to display an image. As shown in FIG. 2, the thermosensitive display 8 here has a thermosensitive recording layer 82 formed on a support (base) 81,
The thermal recording layer 82 is moved so as to be located on the side of the photoconductor 1. The material of the support 81 is not particularly limited, but it can be laminated with the heat-sensitive recording layer 82 and is preferably transparent, specifically, a polyvinyl chloride film, a polyethylene film. , Glass, etc.

The light source 9 is not limited to a specific one as long as it has a wavelength that allows the toner and the like to generate heat upon receiving the light. Specific examples include infrared lamps, ultraviolet lamps, incandescent lamps, fluorescent lamps, and tungsten lamps.

The carrier or the like on the photosensitive member 1 generates heat, and the heat causes an image to be displayed on the heat-sensitive layer 82 of the heat-sensitive display member. Then, the photosensitive member 1 is cleaned and discharged. Although not shown in FIG. 1, plain paper is used in place of the heat-sensitive display body, and assuming that an image can be formed on the plain paper, the transfer unit and the fixing unit are provided like a conventional electrophotographic copying apparatus. If it is provided, it is advantageous that it can be used in the method of the present invention or in a usual electrophotographic copying method, if necessary.

Therefore, the material of the heat-sensitive layer 82 (reversible heat-sensitive recording material) used in the heat-sensitive display by the method of the present invention and the image forming mechanism thereof will be mentioned.
The reversible thermosensitive recording material used in the method of the present invention utilizes transparency change due to heat (transparent state, cloudy opaque state) as described above, in which an organic low molecular weight substance is contained in a resin (in a resin matrix). Those dispersed are preferably used. The difference between the transparent state and the cloudy opaque state is presumed as follows. That is, when transparent, 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 transmitted to the other side without being scattered. Therefore, in the case of white turbidity, the particles of the organic low molecular weight substance are composed of polycrystals of fine crystals of the organic low molecular weight substance, and the crystal axes of the individual crystals point in various directions. Therefore, the light incident from one side is refracted many times at the interface of the crystals of the organic low molecular weight substance particles, and is scattered and thus appears white.

In FIG. 3 (representing the change in transparency due to heat), the resin base material and the heat-sensitive layer mainly composed of the organic low molecular weight substance dispersed in the resin base material are, for example, T _0.
It is cloudy and opaque at room temperature below. When this is heated to the first specific temperature T ₂ , it becomes transparent, and in this state, T ₀ again.
It remains transparent even after returning to room temperature below. This is the temperature T
_{It is considered} that the organic low molecular weight substance goes through a semi-molten state from ₂ to the temperature T ₀ or lower and the crystal grows from a polycrystal to a single crystal. Further, when heated to a second specific temperature of T ₃ or higher, a semitransparent state intermediate between the maximum transparency and the maximum opacity is obtained. Next, when this temperature is lowered, the first cloudy opaque state is restored without taking the transparent state again. It is considered that this is because the organic low molecular weight substance is melted at a temperature of T ₃ or higher and is then cooled to precipitate polycrystals. In addition,
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 of T ₀ or lower, an intermediate state between transparent and opaque can be obtained. Also, the transparent material that has become transparent at room temperature returns to the cloudy and opaque state when heated again to a temperature of T ₃ or higher and then returned to room temperature. That is,
It can take both opaque and transparent forms at room temperature and intermediate forms thereof.

Therefore, the heat sensitive layer can be selectively heated by selectively applying heat to form a cloudy image on a transparent background and a transparent image on a cloudy background, and the change can be repeated many times. It is possible. By arranging a coloring sheet on the back surface of such a heat-sensitive layer, an image of the color of the coloring sheet or a white image of the background of the coloring sheet can be formed on a white background. 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.

Here, the transparentization temperature range is defined as follows. That is, FIG. 4 shows the transparency of the reversible thermosensitive recording material when the reversible thermosensitive recording material in the cloudy state is heated to each temperature including T _{1 to} T ₃ in FIG. 1 and then cooled to a temperature of T ₀ or lower. 4, the transparency of f ₁₃ what was added 80% of the difference between the maximum transparency f ₁₂ and minimum transparency f ₁₁ a transparent state to a minimum transparency f ₁₁ (maximum opaque state), temperature at which f ₁₃ or more transparency Is the clearing temperature, and the range is the clearing temperature range (T _{4 to} T ₅ ), and the width is the clearing temperature range (T ₅
-T ₄₎ to.

To prepare the heat-sensitive recording material used in the present invention, generally, (1) a solution in which two components of a resin base material and an organic low molecular weight substance are dissolved, or (2) a solution of a resin base material (the solvent is an organic low-molecular substance) A dispersion liquid in which an organic low molecular weight substance is dispersed in a fine particle form is used in which at least one kind of molecular substance is not dissolved) is applied on a support such as a plastic film, a glass plate or a metal plate and dried to form a heat sensitive layer. Made by forming. The solvent for forming the heat-sensitive layer or the recording material can be variously selected depending on the types of the base material and the organic low-molecular substance
Examples thereof include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene and the like. The organic low molecular weight substance is precipitated as fine particles and exists in a dispersed state in the heat-sensitive layer or recording material obtained not only when the dispersion is used but also when the solution is used.

The resin base material used for the heat sensitive layer is a material which forms a layer in which an organic low molecular weight substance is uniformly dispersed and held, and which affects the transparency at the time of maximum transparency. Therefore, the resin base material is preferably a resin having good transparency, mechanical stability, and good film forming property. Examples of such resins include polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-vinyl alcohol copolymers, vinyl chloride-vinyl acetate-maleic acid copolymers, and other vinyl chloride-based copolymers. Copolymers; polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-acrylate copolymers and other vinylidene chloride copolymers; polyesters; polyamides; polyacrylates or polymethacrylates or acrylates -Methacrylate copolymer; silicone resin and the like can be mentioned. These may be used alone or in admixture of two or more.

On the other hand, the organic low molecular weight substance may be any substance that changes from polycrystal to single crystal in the recording layer due to heat (changes within the temperature range of T _{1 to} T ₃ shown in FIG. 3).
Generally, those having a melting point of 30 to 200 ° C., preferably about 50 to 150 ° C. are used. Such organic low molecular weight substances include alkanols; alkane diols; halogen alkanols or halogen alkane diols; alkylamines; alkanes; alkenes; alkynes; halogen alkanes; halogen alkenes; halogen alkynes; cycloalkanes; cycloalkenes; cycloalkynes; 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; arylcarboxylic acids or their esters, amides or ammonium salts; halogenallylcarboxylic acids or Thioalcohols; esters, amides or ammonium salts thereof; thiocarboxylic acids or their esters, amines or ammonium salts; thioalcohols Carboxylic acid esters, and the like. These may be used alone or in combination of two or more. The carbon number of these compounds is 10
-60, preferably 10-38, and especially 10-30 are preferred. The alcohol group moiety in the ester may be saturated or unsaturated, and may be halogen-substituted. In any case, the organic low molecular weight substance is at least one kind of oxygen, nitrogen, sulfur and halogen in the molecule, for example,
OH, -COOH, -CONH, -COOR, -NH
_{-, - NH 2, -S -} , - S-S -, - O-, it 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, heptadecanoic acid, stearic acid, behenic acid, nonadecanoic acid, arachidic acid, henicosanoic acid,
Higher fatty acids such as tricosanoic acid, lignoceric acid, pentacosanoic acid, serotic acid, heptacosanoic acid, montanic acid, melicinic acid, and oleic acid; methyl stearate, tetradecyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate, behenic acid. esters of higher fatty acids dodecyl; C ₁₆ H ₃₃ -O
_{-C 16 H 33, C 16 H} 33 -S-C 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 , H ₂₃ C ₁₁ OCO
_{· H 2 C · H 2 C} -O-CH 2 · CH 2 · OCOC 11 H 23,
H ₃₅ C ₁₇ OCO ・ H ₂ C ・ H ₂ C-O-CH ₂・ CH ₂・ O
COC ₁₇ H ₃₅ , H ₃ C ・ H ₂ C ・ (CH ₃ ) HC ・ (C
_{H 2) 15 OOC · H 2} C-O- * * -CH 2 · CH 2 · COO (CH 2) 15 · CH (CH 3)
・ CH ₂・ CH ₃ , H ₂₅ C ₁₂ OCO ・ H ₂ C ・ H ₂ C-S-
CH ₂ · CH ₂ · OCOC ₁₂ H ₂₅ , H ₃₇ C ₁₈ OCO · H ₂
C · H ₂ C—S—CH ₂ · CH ₂ · OCOC ₁₈ H ₃₇ , H ₃ C
・ H ₂ C ・ (CH ₃ ) HC ・ (CH ₂ ) ₁₅ OOC ・ H ₂ C ・
_{H 2 C-S - ** **} - CH 2 · CH 2 · COO (CH 2) 15 · CH (C
H ₃ ) ・ CH ₂・ CH ₃ , H ₃₇ C ₁₈ OOC ・ H ₂ C ・ H ₂ C
_{-NH-CH 2 · CH 2 ·} COOC 18 H 37, H 3 C · H 2 C
_{· (CH 3) HC · (} CH 2) 13 · COO · H 2 C-NH
_{- *** *** - CH 2 · COO} (CH 2) 13 · CH (CH 3) ·
There are ethers such as CH ₂ and CH ₃ or thioethers.
Among them, higher fatty acids, particularly palmitic acid, heptadecanoic acid, nonadecanoic acid, arachidic acid, henicosanoic acid, tricosanoic acid, stearic acid, behenic acid, higher fatty acids having 16 or more carbon atoms such as lignoceric acid are preferred in the present invention, and have 16 to 10 carbon atoms. 24 higher fatty acids are more preferred.

It is preferable that the recording material has a wider transparent temperature range so that it becomes transparent, and it is preferable that the temperature exceeds 15 ° C., more preferably 22 ° C. However, if the transparency temperature range is too wide, the cloudiness temperature rises too much, for example, the thermal sensitivity at the time of forming a cloudy image decreases. Therefore, the transparency temperature range is preferably 80 ° C. or lower, more preferably 50 ° C. or lower.

In order to widen the temperature range in which the material can be made transparent, the organic low molecular weight substances described in this specification may be appropriately combined, or such organic low molecular weight substances may be combined with other materials having different melting points. .. These are disclosed, for example, in JP-A-63
No. 39378, Japanese Patent Application Laid-Open No. 63-130380, etc., Japanese Patent Application No. 63-14754, Japanese Patent Application No. 1-1401.
However, the present invention is not limited thereto.

The weight ratio of the organic low molecular weight substance to the resin base material in the heat sensitive layer is preferably about 2: 1 to 1:16, more preferably 1: 1 to 1: 3. When the ratio of the resin base material is less than this, it becomes difficult to form a film in which the organic low molecular weight substance is retained in the resin base material. Becomes difficult.

In addition to the above components, additives such as a surfactant and a high boiling point solvent may be added to the heat-sensitive layer in order to facilitate the formation of a transparent image. Specific examples of these additives are as follows.

Examples of high boiling point solvents: tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, butyl oleate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, Di-n-octyl phthalate, di-2 phthalate
-Ethylhexyl, diisononyl phthalate, dioctyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, dibutyl adipate, di-n-adipate
Hexyl, di-2-ethylhexyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate,
Di-2-ethylhexyl sebacate, diethylene glycol dibenzoate, triethylene glycol di-2-
Ethyl butyrate, methyl acetylricinoleate, butyl acetylricinoleate, butylphthalylbutyl glycolate, tributyl acetylcitrate.

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 salt of higher alkylbenzene sulfonic acid; higher fatty acid, aromatic carboxylic acid, higher fatty acid sulfonic acid, aromatic sulfonic acid, sulfuric acid monoester Or Ca, Ba or Mg salt of phosphoric acid mono- or di-ester; low degree of sulfated oil; poly long chain alkyl acrylate; acrylic orgomer; poly long chain alkyl methacrylate; long chain alkyl methacrylate-amine containing monomer -Copolymer; styrene-maleic anhydride copolymer; olefin-maleic anhydride copolymer.

The reversible thermosensitive recording materials described so far are
It is a type in which the light-shielding property (transparency) changes reversibly by changing the heating temperature, but in addition to this, it is a type in which color coloring and erasing are performed reversibly by changing the heating temperature. It doesn't matter.

A typical example of the type in which the color is reversibly developed and decolored is a reversible thermochromic composition in which the thermosensitive layer utilizes a color development reaction between an electron-donating color-forming compound and an electron-accepting compound. It is formed by a thing. A thermochromic composition utilizing a color-forming reaction between an electron-donating color-developing compound and an electron-accepting compound is obtained when the electron-donating color-developing compound and the electron-accepting compound are heated and melt-mixed. Amorphous chromophore is produced, while the electron-accepting compound causes crystallization when the amorphous chromophore is heated at a temperature lower than the melting temperature so that the chromophore disappears. It utilizes the phenomenon of.

The thermochromic composition instantly develops color upon heating, and the color development state thereof is stable even at room temperature. On the other hand, the composition in the color development state is instantaneously heated by heating at a temperature below the color development temperature. The color is erased and the erased state is stable even at room temperature, and such a reversible peculiar color developing and erasing behavior is a novel and surprising phenomenon that has never been seen before.

The principle of coloring and erasing, that is, image forming and image erasing when this composition is used as a heat-sensitive recording layer will be described with reference to the graph shown in FIG. The vertical axis of the graph represents the color density, the horizontal axis represents the temperature, the solid line represents the image forming process by heating, and the broken line represents the image erasing process by heating. A is the density in the completely erased state, B is the density in the completely colored state when heated to a temperature of T ₇ or higher, C is the density at a temperature of T ₆ or lower in the completely colored state, and D is T ₆ It shows the density when erased by heating at a temperature between T _{7 and} T ₇ .

This composition according to the present invention is in a colorless state (A) at a temperature of T ₆ or lower. To perform recording (image formation), a color image is formed (B) by heating to a temperature of T ₇ or higher with a thermal head or the like to form a recorded image. Even if the recorded image is returned to the temperature of T ₆ or lower according to the solid line, the state (C) is maintained as it is and the recording memory property is not lost.

Next, in order to erase the recorded image, the formed recorded image is heated to a temperature between T _{6 and} T _{7 which} is lower than the coloring temperature, so as to become a colorless state (D). In this state, the colorless state (A) is maintained as it is even when the temperature is returned to T ₆ or lower. That is, the process of forming the recorded image reaches C by the path of the solid line ABC and the recording is held. Next, in the erasing process of the recorded image, the erasing state is maintained by reaching A through the path of the broken line CDA. The behavioral characteristics of forming and erasing the recorded image are reversible and can be repeated many times.

The reversible thermochromic composition contains a color former and a developer as essential components. Then, the coloring state is formed by heating and melting the color-developing agent and the color-developing agent, while the coloring state is erased by heating at a temperature lower than the coloring temperature, and the coloring state and the decoloring state exist stably at room temperature. Is. As described above, the mechanism of coloring and decoloring in the composition is such that when the coloring agent and the color developer are heated and melt-mixed at the coloring temperature, the composition is amorphized to change the coloring state. On the other hand, it is based on the property that, when heated at a temperature lower than the coloring temperature, the color developing agent of the colored composition causes crystallization to form a color erased state.

A composition comprising an ordinary color-developing agent and a color-developing agent, for example, a leuco compound having a lactone ring, which is a dye precursor widely used in conventional thermal recording paper, and a phenolic compound exhibiting a color-developing effect. When this is melt-mixed by heating, it becomes a colored state based on the ring opening of the lactone ring of the leuco compound. This colored state is an amorphous state in which both are compatible. Although this colored amorphous state is stable at room temperature, it does not crystallize even when heated again, and since the phenolic compound is not separated from the leuco compound, there is no ring closure of the lactone ring and decolorization occurs. I don't.

On the other hand, when the composition of the color former and the developer according to the present invention is also melt-mixed by heating, it becomes a color-developed state, exhibits an amorphous state as in the conventional case, and is stable at room temperature. Exist. However, in the case of the present invention, when the composition in the colored amorphous state is heated below the coloring temperature, that is, at a temperature at which the molten state is not reached, the developer is crystallized and becomes compatible with the coloring agent. The bond due to the state cannot be maintained, and the color developer separates from the color developer. It is considered that the color developer cannot accept electrons from the color developer due to separation from the color developer due to crystallization of the color developer, and the color developer is decolorized.

The above-mentioned peculiar coloring and decoloring behavior observed in the thermochromic composition is the mutual solubility of the color former and the color developer by heating and melting, the strength of both actions in the color developing state, and the color developer. Is related to the solubility of the color developing agent, the crystallinity of the color developer, etc.
In principle, it causes amorphization by heating and melting, while
Any color former / developer system that causes crystallization by heating at a temperature lower than the color development temperature can be used as a composition component in the present invention. Further, those having such characteristics show endothermic change due to melting and exothermic change due to crystallization in thermal analysis, so that the color former / developer system applicable to the present invention can be easily analyzed by thermal analysis. You can check. Further, the reversible thermochromic composition system according to the present invention may contain a third substance, for example, the reversible decoloring behavior thereof is retained even if a polymer substance is present. Was confirmed.

In the thermochromic composition of the present invention, the decoloring is caused by the separation from the color former due to the crystallization of the color developer, and therefore, in order to obtain a composition having an excellent decolorizing effect, The choice of is important.

Next, the color developers preferably used in the present invention are exemplified as follows. As described above, the color developers applicable to the present invention can be easily found by thermal analysis. It is not limited to ones. (1) Organic phosphoric acid compound represented by the following general formula (1) R ¹ —PO (OH) ₂ (1) (wherein R ¹ is a linear or branched alkyl group or alkenyl having 8 to 30 carbon atoms) Representing a group) Specific examples of this organic phosphoric acid compound include the following. Octylphosphonic acid, nonylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid.

(2) Organic acid having a hydroxyl group at the α-position carbon represented by the following general formula (2) R ² —CH (OH) COOH (2) (wherein R ² is a straight chain having 6 to 28 carbon atoms) Represents a linear or branched alkyl group or an alkenyl group). Specific examples of the organic acid having a hydroxyl group at the α-position carbon include the following. α-hydroxyoctanoic acid, α-hydroxydodecanoic acid, α-hydroxytetradecanoic acid,
α-Hydroxyhexadecanoic acid, α-hydroxyoctadecanoic acid, α-hydroxypentadecanoic acid, α-hydroxyeicosanoic acid, α-hydroxydocosanoic acid and the like.

The color former used in the present invention is a compound exhibiting an electron-accepting property, and is a colorless or light-colored dye precursor per se, and is not particularly limited, and conventionally known ones, for example, triphenylmethanephthalide-based compounds. There are compounds, fluoran compounds, phenothiazine compounds, leuco auramine compounds, rhodamine lactam compounds, spiropyran compounds, indolinophtalide compounds, and the like. Specific examples include the following. 3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3, 3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-
Diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np
-Tolyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino } -6-Diethylaminofluorane, 2- {3,6-bis (diethylamino) -6- (o
-Chloranilino) xanthyl benzoate lactam}, 3
-Diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7
-(O-chloranilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-N
-Methyl-N-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- Anilino Fluoran, 3
-(N, N-diethylamino) -5-methyl-7-
(N, N-dibenzylamino) fluorane, benzoleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-2'-
Methoxy-benzoindolino-spiropyran, 3-
(2'-hydroxy-4'-dimethylaminophenyl)
-3- (2'methoxy-5'-chlorophenyl) phthalide, 3- (2'hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- ( 2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4 '
-Dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methoxyphenyl) phthalide,
3-morpholino-7- (N-propyl-trifluoromethylaniline) fluorane, 3-diethylamino-5-
Chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenyl Ethylamino) fluorane, 3- (N-ethyl-p-toluidino)
-7- (α-phenylethylamino) fluorane, 3-
Diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3
-Diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methoxytoluidino) -7- (pn
-Butylanilino) fluorane, 3- (N-methyl-N)
-Isopropylamino) -6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorene spiro (9,3 ')- 6'-Dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4 '
-Bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2
-Ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane,
3-diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluorane, 3-N-methyl-N-
Isobutyl-6-methyl-7-anilinofluorane, 3
-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7
-(2 ', 4'-dimethylanilino) fluorane and the like.

Particularly preferred color formers used in the present invention are those containing halogen as a substituent. Examples of such a thing include the following. 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3-cyclohexylamino-6-chlorofluorane, 3-cyclohexylamino-6-bromofluorane, 3-diethylamino-7-chlorofluorane, 3 -Diethylamino-7-bromofluorane, 3-
Dipropylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-phenylamino-fluorane, 3-pyrrolidino-6-chloro-7-phenylamino-fluorane, 3-diethylamino-6-chloro-7-
(M-Trifluoromethylphenyl) amino-fluorane, 3-cyclohexylamino-6-chloro-7- (o
-Chlorophenyl) amino-fluorane, 3-diethylamino-6-chloro-7- (2 ', 3'-dichlorophenyl) amino-fluorane, 3-diethylamino-6-
Methyl-7-chlorofluorane, 3-dibutylamino-
6-chloro-7-ethoxyethylamino-fluorane,
3-diethylamino-7- (o-chlorophenyl) amino-fluorane, 3-diethylamino-7- (o-bromophenyl) amino-fluorane, 3-diethylamino-7- (o-chlorophenyl) amino-fluorane, 3
-Dibutylamino-7- (o-fluorophenyl) amino-fluorane, 6'-bromo-3'-methoxybenzoindolino-pyrrilospirane, 3- (2'-methoxy-
4'-Dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2 '-Methoxy-5'-chlorophenyl) phthalide, 2- {3,6-bis (diethylamino)}-9- (o-chlorophenyl) amino-xanthyl lactam benzoate and the like.

The color former preferably used in the present invention is a compound represented by the following general formula (3).

[Chemical 1] (However, R ³ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ⁴ is a hydrogen atom or an optionally substituted amino group, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenylamino group. , M is an integer of 1 or 2, Y is a carbon number of 1 to 4.
Alkyl group or alkoxy group having 1 to 2 carbon atoms, n is 1
Or represents an integer of 2. )

Specific examples of the compound represented by the general formula (3) include the followings. 3- (N-methyl-N-phenylamino) -7-amino-fluorane, 3- (N-ethyl-N-phenylamino) -7-amino-fluorane, 3- (N-propyl-)
N-phenylamino) -7-amino-fluorane, 3-
{N-methyl-N- (p-methylphenyl) amino}-
7-amino-fluorane, 3- {N-ethyl-N- (p
-Methylphenyl) amino} -7-amino-fluorane, 3- {N-propyl-N- (p-methylphenyl)
Amino} -7-amino-fluorane, 3- {N-methyl-N- (p-ethylphenyl) amino} -7-amino-
Fluorane, 3- {N-ethyl-N- (p-ethylphenyl) amino} -7-amino-fluorane, 3- {N-
Propyl-N- (p-ethylphenyl) amino} -7-
Amino-fluorane, 3- {N-methyl-N- (2 ',
4'-Dimethylphenyl) amino} -7-amino-fluorane, 3- {N-ethyl-N- (2 ', 4'-dimethylphenyl) amino} -7-amino-fluorane, 3-
{N-propyl-N- (2 ', 4'-dimethylphenyl)
Amino} -7-amino-fluorane, 3- {N-methyl-N- (p-chlorophenyl) amino} -7-amino-
Fluorane, 3- {N-ethyl-N- (p-chlorophenyl) amino} -7-amino-fluorane, 3- {N-
Propyl-N- (p-chlorophenyl) amino} -7-
Amino-fluorane, 3- (N-methyl-N-phenylamino) -7-methylamino-fluorane, 3- (N-
Ethyl-N-phenylamino) -7-methylamino-fluorane, 3- (N-propyl-N-phenylamino)-
7-methylamino-fluorane, 3- {N-methyl-N
-(P-methylphenyl) amino} -7-ethylamino-fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -7-benzylamino-fluorane,
3- {N-methyl-N- (2 ', 4'-dimethylphenyl) amino} -7-methylamino-fluorane, 3-
{N-ethyl-N- (2 ', 4'-dimethylphenyl) amino} -7-ethylamino-fluorane, 3- {N-methyl-N- (2', 4'-dimethylphenyl) amino}-
7-benzylamino-fluorane, 3- {N-ethyl-
N- (2 ', 4'-dimethylphenyl) amino} -7-benzylamino-fluorane, 3- (N-methyl-N-phenylamino) -7-dimethylamino-fluorane, 3
-(N-ethyl-N-phenylamino) -7-dimethylamino-fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -7-diethylamino-fluorane, 3- {N-ethyl- N- (p-methylphenyl) amino} -7-diethylamino-fluorane, 3- (N-
Methyl-N-phenylamino) -7-dipropylaminofluorane, 3- (N-ethyl-N-phenylamino)-
7-dipropylaminofluorane, 3- {N-methyl-
N- (p-methylphenyl) amino} -7-dibenzylamino-fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -7-dibenzylamino-fluorane, 3- {N- Ethyl-N- (p-methylphenyl) amino} -7-di (p-methylbenzyl) amino-
Fluoran, 3- {N-methyl-N- (p-methylphenyl) amino} -7-acetylamino-fluorane, 3
-{N-ethyl-N- (p-methylphenyl) amino}
-7-benzoylamino-fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -7- (o-
Methoxybenzoyl) amino-fluorane, 3- {N-
Ethyl-N- (p-methylphenyl) amino} -6-methyl-7-phenylamino-fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -6-methyl-7-phenylamino -Fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -6-ter
t-Butyl-7- (p-methylphenyl) amino-fluorane, 3- (N-ethyl-N-phenylamino) -6
-Methyl-7- (N-ethyl-N- (p-methylphenyl) amino-fluorane, 3- {N-propyl-N-
(P-Methylphenyl) amino} -6-methyl-7-
{N-methyl-N- (p-methylphenyl) amino}-
Fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -5-methyl-7-benzylamino-fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -5 -Chloro-7-dibenzylamino-fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -5-methoxy-7-dibenzylamino-
Fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -6-methyl-fluorane, 3- {N-
Ethyl-N- (p-methylphenyl) amino} -5-methoxy-fluorane and the like.

The color developing agents are applied alone or in admixture of two or more. Similarly, the color-developing agent can be used alone or in combination of two or more. In the thermochromic composition, the color former and the color developer can be used as they are or by being encapsulated in microcapsules. Such a reversible heat-sensitive recording material can be obtained by uniformly dispersing or dissolving a color former and a developer together with a binder in water or an organic solvent according to a conventionally known method, and coating this on a substrate. ..

As the binder, various conventional binders can be appropriately used, and examples thereof include polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, methoxy cellulose, carboxymethyl cellulose, methyl cellulose, cellulose acetate, gelatin, casein, starch, polyacrylic acid. Soda, polyvinylpyrrolidone, polyacrylamide, maleic acid copolymer, acrylic acid copolymer, polystyrene, polyvinyl chloride, polyvinyl acetate, polyacrylic acid esters, polymethacrylic acid esters, vinyl chloride-
Examples include vinyl acetate copolymers, styrene copolymers, polyesters and polyurethanes.

Microencapsulation of the color former and / or the developer is carried out by the coacervation method, interfacial polymerization method, Insi
It can be carried out by a known method such as a tu polymerization method. In the present invention, various additives such as a dispersant, a surfactant, a filler, a color image stabilizer and an antioxidant which are used in a usual thermal recording paper are used for the purpose of improving coating properties or recording properties as required. As mentioned above, agents, light stabilizers, lubricants and the like can be added.

[0047]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. Parts herein are by weight.

Example 1 Behenic acid 6 parts Eicosane diacid 4 parts Diphthaline phthalate 2 parts Vinyl chloride-vinyl acetate-phosphate ester copolymer 20 parts (made by Denki Kagaku Kogyo Co., Ltd.) , Denka vinyl # 1000P) A solution of 150 parts of tetrahydrofuran was applied and dried by heating to provide a heat-sensitive layer (reversible heat-sensitive recording layer) having a thickness of about 10 μm. The recording material thus obtained was in a cloudy state. The transparent temperature range of this recording material was 25 ° C. This recording material 8
The whole was clarified by heating to 0 ° C. This thermosensitive display is passed through the process shown in FIG. 1, and when a toner image is formed by an electrophotographic process, it is brought into contact with the photoconductor and irradiated with light from the back side, so that only the toner image part is displayed. It turned cloudy. In this way, the heat sensitive layer is only in contact with the photoconductor and toner, and much less pressure is applied compared to printing with a thermal head, so it is possible to print uniformly on a hard or soft transparent substrate. Became.
Further, since the pressure on the heat sensitive layer is small, the durability of the heat sensitive layer is also improved.

Comparative Example The same thermosensitive display as used in Example 1 was prepared, and the thermosensitive display was clouded with a thermal head. I got it. In such a hard substrate such as a vinyl chloride card, printing unevenness due to the pressure of the thermal head,
The substrate is destroyed, and printing with such a thermal head on the substrate is impossible.

[0050]

According to the present invention, since a toner image or the like is printed by heating, the heat sensitive layer and the printing portion (heating portion) are used.
Is only in contact with each other, and the damage due to the heat and pressure of the thermal head so far is eliminated, and the life of the thermal display is extended. Further, according to the present invention, it becomes possible to uniformly print on a hard substrate or a soft substrate such as a vinyl chloride card, which has been impossible to print with a thermal head.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a reversible thermosensitive recording apparatus of the present invention.

FIG. 2 is a cross-sectional view of a reversible thermosensitive recording medium used for carrying out the method of the present invention.

FIG. 3 is a diagram for explaining a change in transparency due to heat of the heat-sensitive layer used in the method of the present invention.

FIG. 4 is a diagram for explaining the definition of a transparentization temperature range.

FIG. 5 is a diagram for explaining a change in color density due to heat of another heat-sensitive layer used in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive member 2 Charging part 3 Exposure part 4 Developing part 5 Cleaner part 6 Discharging part 7 Paper feed roller (paper feed part) 8 Thermal display (81 support, 82 thermal recording layer) 9 Light source

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Kawaguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Company (72) Inventor Tetsuya Amano 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Company Ricoh

Claims (3)

[Claims] 1. An electrostatic charge image is formed on an electrophotographic photosensitive member, and the electrostatic charge image is developed with a carrier containing or coated with a toner or a light-absorbing substance, and then the image-like toner or carrier is transferred onto a transparent support. In a state where the thermosensitive display having a thermosensitive layer whose transparency or color reversibly changes depending on the temperature is in contact with the thermosensitive layer, light is applied from the transparent support side to heat the image-like toner or carrier. A method for forming a reversible thermosensitive recording image, characterized in that the heat is applied to the thermosensitive layer to form an image. 2. The method for forming a reversible thermosensitive recording image according to claim 1, wherein the thermosensitive display has a thermosensitive layer that is transparent before image formation. 3. An electrophotographic copying machine comprising an electrophotographic photoreceptor, a charging section, an exposing section, a developing section, a transferring section, a light source section, a cleaner section, a discharging section, a sheet feeding section and a fixing section. When using all except the above-mentioned light source section, when using as a reversible thermosensitive recording image display device, by using the developing section and all other than the above-mentioned transfer section and fixing section, electrophotography A reversible thermosensitive recording image display device, which can be used in both a copying apparatus and a reversible thermosensitive recording image forming apparatus.