JPH0624128A - Reversible thermal recording material - Google Patents

Abstract

PURPOSE:To provide a reversible thermal recording material, in which abrasion resistance with a thermal head is improved, a flaw to a surface is prevented, the cutting of an image due to the adhesion of head chips is obviated and printability is enhanced. CONSTITUTION:In a reversible thermal recording material, in which a heat- sensitive layer, which mainly comprises a resin matrix and an organic low molecular substance dispersed into the resin matrix and transparency of which reversibly changes while depending upon a temperature, is formed onto a support and a printed layer is formed onto the surface of the heat-sensitive layer, the reversible thermal recording material, in which a smoothened layer is shaped onto the surface of the printed layer, particularly the smoothened layer is formed while using a silicone modified electron-ray curable resin as a main component. Or the smoothened layer is formed while mainly comprising the silicone modified electron-ray curable resin and an electron-ray curable resin having five functions or more of branched molecular structure employing polyester as a skeleton.

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 repeatedly forming and erasing an image by utilizing reversible transparency change with temperature of a thermosensitive layer.

[0002]

2. Description of the Related Art In recent years, reversible heat-sensitive recording materials have been attracting attention because they can form images temporarily and can erase the images when they are no longer needed. As a typical example, the glass transition temperature (Tg) is from 50 to 60 ° C. to 8
A reversible thermosensitive recording material is known in which an organic low molecular weight substance such as a higher fatty acid is dispersed in a resin matrix such as a vinyl chloride-vinyl acetate copolymer having a low glass transition temperature of less than 0 ° C. JP-A-54-119377, JP-A-55-1
54198 and the like).

Further, in order to prevent the surface from being deformed by the heat and pressure of a heating means such as a thermal head and lowering the transparency of the transparent portion, protection using a heat resistant resin such as an ultraviolet curable resin or an electron beam curable resin is used. The one provided with a layer is disclosed in JP-A-1-
It is described in Japanese Patent Laid-Open No. 133781 and Japanese Patent Laid-Open No. 2-566.

In this reversible thermosensitive recording material, when an image is formed by a heating element such as a thermal head, the reversible thermosensitive recording material is scratched on the surface of the reversible thermosensitive recording material by repeating the image formation and erasing by the heat and pressure of the thermal head. However, there is a drawback that the surface is gradually scraped off and an image cannot be formed.
Further, the scraps scraped off adhere to the thermal head, which causes a defect such as image cut. In order to eliminate these drawbacks, measures have been taken to weaken the heat and pressure of the thermal head, but image formation and erasing are insufficient, and they have not yet been resolved.

Further, in the reversible thermosensitive recording material surface, a measure is taken to add heat resistance and lubricity to the surface as a protective layer, but in the card use, the above-mentioned measures are taken for printing on the surface. There are problems such as defective printing adhesion and poor printability, and the prevention of dust adhesion to the thermal head has not been solved.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a reversible heat-sensitive recording material which solves the above-mentioned drawbacks, can form a uniform image even when a large number of sheets are continuously printed, and has good printability. With the goal.

[0007]

According to the present invention, a resin base material and an organic low-molecular substance dispersed in the resin base material are contained as a main component on a support, and a transparent state and a cloudiness are obtained depending on temperature. A reversible thermosensitive recording material having a thermosensitive layer whose state reversibly changes and a printing layer provided on the surface of the reversible thermosensitive recording material, wherein a slipping layer is provided on the surface of the printing layer. A material is also provided, and the reversible thermosensitive recording material is provided, wherein the slipping layer is formed by using a silicone-modified electron beam-curable resin as a main component.
It is characterized in that the slipping layer is formed mainly of an electron beam curable resin having a branched molecular structure of 5 or more functional groups having a silicone-modified electron beam curable resin and polyester as a skeleton. The reversible thermosensitive recording material is provided, and in particular, the weight ratio of the electron beam curable resin having a branched molecular structure of 5 or more functional groups having a polyester skeleton to the silicone-modified electron beam curable resin is 2: 8 to. 7:
The above reversible thermosensitive recording material is provided.

In the reversible thermosensitive recording material, the present inventors have good printability and are resistant to heat and pressure of a thermal head or a heat roll, and prevent surface scratches and thermal head residue sticking by the thermal head. As a result, the heat resistance and pressure resistance of the surface of the printing layer are improved and the coefficient of friction with the thermal head is reduced. As the material having good heat resistance and pressure resistance, an electron beam curable resin having a branched molecular structure of 5 or more functional groups having a polyester skeleton is most suitable, and a material having a low friction coefficient, that is, a silicone-modified lubricant is used as a lubricant. We have found that electron beam curable resins are optimal.

When recording and erasing are repeated by heating and pressure of a thermal head or a heat roll, the toughness required is a specific electron beam curable resin (branched molecular structure of 5 or more functional groups having polyester as a skeleton). Type of) acts,
Furthermore, in order to improve the sliding between the thermal head and the surface of the slippery layer, the specific electron beam-curable resin (silicone-modified type) acts on the slippery surface, making it difficult for the slippery surface to be scraped. Thus, even if printed, scratches are unlikely to occur and dust is not accumulated on the thermal head, and uniform image formation is possible. The present invention has been made based on such findings.

The present invention will be described in more detail below. As mentioned above, the slipping layer in the present invention is an electron beam curable resin (hereinafter referred to as “electron beam curable acrylic modified polyurethane resin”) having a branched molecular structure of 5 or more functional groups having a polyester as a skeleton. And a silicone-modified electron beam curable resin as a main component.

The electronically curable acrylic-modified polyurethane resin can be produced, for example, as follows. That is, the reaction product of 1,4-butanediol and adipic acid,
Alternatively, a diisocyanate and a compound having an acrylic double bond are added to a mixture of a polyester diol such as a reaction product of propylene glycol and adipic acid (the above are equivalent to the polyester skeleton) and a polyether triol. It can be produced by reacting. Instead of the mixture of polyester diol and polyether triol, for example, a mixture of polyester diol and polyester triol or a mixture of polyether diol and polyester triol may be used. The electron-curable acrylic-modified polyurethane resin of the present invention is, for example, a terminal hydrogen group of a polyurethane having a polyester skeleton and / or obtained by the above reaction.
Alternatively, it is a compound in which an isocyanate group and a compound having an acrylic double bond are bonded to each other and which has five or more two acrylic type two bonds which are electron beam curable functional groups in one molecule.

Here, the diisocyanate is 2,
4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,6-hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, methylene bis (4-phenylisocyanate), etc. are also used as compounds having an acrylic double bond. Is 2-hydroxyethyl (meth) acrylate, 2
Examples thereof include hydroxypropyl (meth) acrylate and hydroxypropyl (meth) acrylate. The polyester diol can be obtained, for example, as Adeka New Ace Y4-30 (manufactured by Asahi Denka Kogyo Co., Ltd.), and the polyether triol can be obtained, for example, as Sannic TP-400, Sannix GP-3000 (above, Sanyo Kasei Co., Ltd.) and the like. .

The molecular weight of the polyester portion of this electron-curable acrylic-modified polyurethane resin is 200 in order to provide the flexibility and toughness required for the heat-resistant slip layer.
The range of 0 to 4000 is preferable. Further, the molecular weight of the entire electron beam-curable acrylic modified polyurethane resin is preferably in the range of 20,000 to 50,000 for the same reason as above. In addition, in this resin, effects such as acceleration of curing and improvement of hardness can be exerted by providing 5 or more functional groups, preferably 7 to 13 functional groups.

On the other hand, the silicone-modified electron beam curable resin is represented by the following chemical formula 1.

[Chemical 1] This silicone-modified electron beam-curable resin has excellent film-forming properties, so that a uniform and thin film can be satisfactorily formed, and since it has a silicone functional group, it has an excellent sliding effect.

The weight ratio of the electron beam curable acrylic modified polyurethane resin to the silicone modified electron beam curable resin is preferably in the range of 2: 8 to 7: 3. If the proportion of the silicone-modified electron beam-curable resin is high, the binding force will be poor, and if it is low, on the other hand, the sliding function will be deteriorated and problems such as scratches on the surface and adhesion of head residue will occur.

In the slipping layer of the present invention, it is desirable to use other polyfunctional electron beam curable monomers in combination in order to accelerate the curing during the formation process and to bring out the heat resistance effect. This monomer acts as a cross-linking accelerator and is advantageous in forming a complicated and dense cross-linked structure. Specific examples of such a monomer include trimethylol propane triacrylate, tetramethyl roll methaneterola acrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate and the like. It is desirable that the monomer is added in an amount of up to 50 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the electron beam curable acrylic modified polyurethane resin.

The thickness of the slipping layer is 0.
It is preferably 5 to 10 μm. When the thickness is less than this, the protective effect is lowered, and when the thickness is more than this, the thermal sensitivity is lowered.

The reversible thermosensitive recording material of the present invention utilizes the transparency change (transparent state, cloudy opaque state) as described above, and the difference between the transparent state and the 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 matrix are composed of large particles of the organic low-molecular substance, and the light incident from one side is not scattered and is opposite. It appears to be transparent because it is transmitted to the side, and (ii) in the case of turbidity, the particles of the organic low-molecular substance are composed of polycrystals of fine crystals of the organic low-molecular substance, and the crystal axis of each crystal Since the light is directed in various directions, the light incident from one side is refracted many times at the interface of the crystal of the organic low molecular weight substance particles, and is scattered and thus appears white.

In FIG. 1 (representing the change in transparency due to heat), a thermosensitive layer mainly composed of a resin base material and an organic low molecular weight substance dispersed in the resin base material is, for example, T
It is cloudy and opaque at room temperature below ₀ . This is the temperature T ₂
When it is heated to ₀ , it becomes transparent, and even if it is returned to room temperature below T _{0 in} this state, it remains transparent. This is the temperature T ₂ to T ₀
It is considered that the organic low molecular weight substance is in a semi-molten state until the following and the crystal grows from a polycrystal to a single crystal.
Upon further heating to T ₃ or more temperature becomes translucent state intermediate between the maximum transparency and the maximum opacity. 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 when the organic low molecular weight substance is melted at a temperature of T ₃ or higher, the polycrystal is deposited 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 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 again when heated to a temperature of T ₃ or higher and then returned to room temperature. That is, both opaque and transparent forms at room temperature and intermediate forms thereof can be obtained.

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, it is possible to form an image of the color of the coloring sheet on a white background or an image of the white background on the background of the coloring sheet. 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.

In order 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 erasure, or to change the applied energy conditions. Therefore, it is effective to use a thermal head having a single thermal head for image formation and image deletion. In the former case, the cost of the apparatus increases because two thermal heads are required, but if the reversible heat-sensitive recording material is passed once with different energy application conditions for each thermal head, image formation and erasure can be performed. You can do it. In the latter case, since the image is formed and erased by one thermal head, the conditions for applying energy to the thermal head at one time when the thermal recording material passes should be adjusted according to the image forming portion and the erasing portion. The operation is complicated, but the operation is complicated, such as changing finely, or erasing the image on the thermal recording material once and then running the thermal recording material again in the opposite direction to form an image under different energy conditions. Therefore, the equipment cost is reduced.

To prepare the reversible thermosensitive recording material of the present invention,
For example, the heat-sensitive layer can be formed as a film on a supporting member such as a plastic film, a glass plate, a metal plate or the like by the following method, or can be formed into a sheet. 1) A method in which a resin base material and an organic low molecular weight substance are dissolved in a solvent, which is applied onto a support member, and the solvent is evaporated to form a film or sheet. 2) The resin base material is dissolved in a solvent that dissolves only the resin base material, and the organic low molecular weight substance is pulverized or dispersed therein by various methods, and this is applied onto a support member, and the solvent is evaporated to form a film. Or the method of making a sheet. 3) A method in which a resin base material and an organic low-molecular substance are heated and melted and mixed without using a solvent, and this is molded into a film or sheet and cooled. As the solvent for forming the heat-sensitive layer or the heat-sensitive recording material, various selections can be made according to the types of the resin 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 obtained not only when the dispersion liquid is used but also when the solution is used.

In the present invention, the resin used as the resin base material of the thermosensitive layer of the reversible thermosensitive recording material is preferably a resin which can form a film or a sheet, has good transparency and is mechanically stable. Examples of such resins include polyvinyl chloride; vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer. Vinyl chloride-based copolymers such as polymers; polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymers, vinylidene chloride-based copolymers such as vinylidene chloride-acrylonitrile 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, as the organic low molecular weight substance, any substance that changes from polycrystal to single crystal due to heat in the recording layer (changes within the temperature range of T _{1 to} T ₃ shown in FIG. 1) may be used.
Generally a melting point of 30 to 200 ° C, preferably 50 to 150 ° C.
Something is used. Such organic low-molecular substances include alkanols; alkane diols; halogen alkanols or halogen alkane diols; alkylamines; alkanes; alkenes; alkynes; halogen alkanes; halogen alkenes; halogen alkynes; cycloalkanes; cycloalkenes; cycloalkynes; saturated or 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 admixture 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 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, as these compounds,
Uric acid, dodecanoic acid, myristic acid, pentadecane
Acid, palmitic acid, pentadecanoic acid, stearic acid,
Laquinic acid, behenic acid, henicosanoic acid, tricosanoic acid,
Lignoceric acid, pentacosanoic acid, cerotic acid, hepta
Cosanoic acid, montanic acid, melissic acid, nonadecanoic acid, o
Higher fatty acids such as rain acid; methyl stearate, steer
Tetradecyl phosphate, Octadecyl stearate, Lau
Octadecyl phosphate, tetradecyl palmitate, behe
Esters of higher fatty acids such as dodecyl acidate; C₁₆H₃₃-OC₁₆H₃₃ , C₁₆H₃₃-SC₁₆H₃₃
 , C₁₈H₃₇-SC₁₈H₃₇ , C₁₂H_{twenty five}-SC₁₂H_{twenty five}
 , C₁₉H₃₉-SC₁₉H₃₉ , C₁₂H_{twenty five}-S-S-C₁₂
H_{twenty five} ， Etc., such as ether or thioether. Above all, the present invention
Higher fatty acids, especially palmitic acid, pentadecanoic acid,
Nonadecanoic acid, arachidic acid, stearic acid, behenic acid,
Lignoceric acid, serotic acid, margaric acid, Heniko
Higher fats with 16 or more carbon atoms such as sanic acid and tricosanoic acid
Acids are preferable, and higher fatty acids having 16 to 24 carbon atoms are more preferable.
Good

It is also possible to use one of the above-mentioned organic molecular substances as an organic low molecular substance and another type of organic low molecular substance as a substance for controlling crystal growth. For example, stearic acid is used as an organic low molecular weight substance, and stearyl alcohol is used as a substance for controlling crystal growth.

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. If the ratio of the resin base material is below this range, it will be difficult to form a film in which the organic low molecular weight material is retained in the resin base material. Becomes difficult.

The thickness of the heat sensitive layer is preferably 1 to 3 μm, and 2
˜20 μm is more preferred. If the heat-sensitive layer is too thick, heat distribution will occur in the layer and it will be difficult to achieve uniform transparency. On the other hand, if the heat-sensitive layer is too thin, the white turbidity is lowered and the contrast is lowered. Further, the white turbidity can be increased by increasing the amount of the organic low molecular weight 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 the 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-azelaate
Ethylhexyl, dibutyl sebacate, di-sebacate
2-ethylhexyl, diethylene glycol dibenzoate, triethylene glycol di-2-ethylbutyrate, 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 to amine-containing mono Chromatography copolymers; styrene-maleic anhydride copolymer; olefin-maleic anhydride copolymer.

In order to prevent the surface of the heat-sensitive layer of the present invention from being deformed by the heat and pressure of a heating means such as a thermal head by a writing method to reduce the transparency of the transparent portion, conventional reversible heat-sensitive recording is performed. A protective layer may be provided similarly to the material. The thickness of the protective layer is 1 to 15 μm, preferably about 2 to 10 μm. If the thickness of the protective layer is less than 1 μm, the heat-sensitive layer cannot be used as a protective layer,
If it exceeds m, the heat sensitivity of the heat-sensitive layer is lowered. Examples of the material of the protective layer laminated on the heat-sensitive layer include silicone rubber, silicone resin, polysiloxane graft polymer, ultraviolet curable resin, electron beam effect resin and the like. In any case, a solvent is used at the time of coating, but it is desirable that the solvent is difficult to dissolve the resin of the thermosensitive layer and the organic low molecule. Examples of the solvent that hardly dissolves the resin and the organic low molecule in the heat-sensitive layer include n-hexane, methyl alcohol, ethyl alcohol, isopropyl alcohol, and the like, and the alcohol solvent is particularly preferable from the viewpoint of cost.

Further, an intermediate layer may be provided between the protective layer and the reversible recording material in order to protect the reversible recording material from the solvent and monomer components of the protective layer forming liquid (JP-A-1-133781). No. publication). As the material for the intermediate layer, the following thermosetting resins and thermoplastic resins can be used in addition to those listed as the resin base material in the heat sensitive layer.
That is, specifically, polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl butyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide and the like can be mentioned. Although the thickness of the intermediate layer varies depending on the use, it is preferably about 0.1 to 2 μm. If it is less than this, the protective effect is lowered, and if it is more than this, the thermal sensitivity is lowered.

The printing layer is not particularly limited, but UV curable ink is preferable. The thickness of the printing layer is preferably about 0.5 to 5 μm.

[0034]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In addition, both parts and% are based on weight. Example 1 Behenic acid 6 parts Eicosane diacid 4 parts Diisodecyl phthalate 3 parts Vinyl chloride-vinyl acetate copolymer (UCC) 25 parts Tetrahydrofuran 180 parts Toluene 20 parts on a transparent PET having a thickness of about 100 μm. Is applied with a wire bar and dried by heating to about 1
A heat-sensitive layer having a thickness of 5 μm was provided. A solution of polyamide resin (CM8000 manufactured by Toray Industries, Inc. CM8000) 10 parts methyl alcohol 90 parts was applied on it with a wire bar and dried by heating to form an intermediate layer of about 0.5 μm thickness, and urethane acrylate UV curing was applied on the intermediate layer. 75% butyl acetate solution of a water-soluble resin (Dainippon Ink and Chemicals, Unidick C7-157) 10 parts A solution consisting of 10 parts toluene is evenly dispersed, and then applied with a wire bar and heated and dried to 80 w / cm. Was provided with a protective layer of about 2 μm, which was cured by the ultraviolet lamp. Further, an VV ink was used to print an arbitrary pattern on the surface by an offset printing method, and the surface was cured by an ultraviolet lamp to form an ink layer having a thickness of about 1.5 μm. Furthermore, an electron beam curable acrylic-modified polyurethane resin [Adeka New Ace Y4-30 manufactured by Asahi Denka Co., Ltd., whose polyester part has a molecular weight of about 3000 and Polyester Triol TP-400 (manufactured by Sanyo Chemical Co., Ltd.) and 2, Reaction product having a branched structure of 6-tolylene diisocyanate and hydroxyethyl acrylate; 10 functional groups, total molecular weight of about 30000] 7 parts Polyfunctional monomer (M-8030 manufactured by Toagosei Kasei Co., Ltd.) 3 parts Silicone Modified urethane acrylate (19-4842, manufactured by Freeman Inc., USA) 3 parts MEK / toluene (1/1) mixed solvent 50 parts uniformly dispersed, then coated with a wire bar, heated and dried, and electron beam irradiated (1M). The reversible thermosensitive recording material of the present invention was prepared by providing a slipping layer having a thickness of about 2 μm.

Example 2 The present invention was carried out in the same manner as in Example 1 except that the ratio 7: 3 of the electron beam curable acrylic modified polyurethane resin to the silicone modified electron beam curable resin of Example 1 was changed to 2: 8. A reversible thermosensitive recording material was prepared.

Example 3 A reversible thermosensitive recording material of the present invention was prepared in the same manner as in Example 1 except that the electron beam curable acrylic modified polyurethane resin of Example 1 was removed and only the silicone modified electron beam curable resin was used. .

Example 3 A reversible thermosensitive recording material of the present invention was prepared in the same manner as in Example 1 except that only the electron beam curable acrylic modified polyurethane resin was removed except the silicone modified curable resin of Example 1.

Comparative Example 1 A comparative reversible thermosensitive recording material was prepared in the same manner as in Example 1 except that the slipping layer of Example 1 was omitted.

Comparative Example 2 A comparative reversible thermosensitive recording material was prepared in the same manner as in Example 1 except that the material for the slipping layer in Example 1 was silicone oil.

Comparative Example 3 A comparative reversible thermosensitive recording material was prepared in the same manner as in Example 1 except that the material for the slipping layer of Example 1 was a crosslinked cured resin of silicone-modified polyurethane and polyisocyanate.

These reversible thermosensitive recording materials were heated to 80 ° C. to make them transparent, and then evaluated using a thermal head printing test device manufactured by Yagi Electric Co., Ltd. As the thermal head, a thin film whole surface grace type thermal head manufactured by Ricoh Co., Ltd. was used, and the platen pressure was 1.0 kg / head and the pulse width was 1.
Printing was performed under the conditions of 0 ms and a voltage of 23V. Debris adhered to the thermal head was judged by an optical microscope, images were cut off, and surface scratches were judged visually. The results are shown below in Table 1.

[0042]

[Table 1] Image deterioration: The difference between the initial cloudiness density and the cloudiness density after 100 times is shown. White turbidity density-measured with Macbeth reflection densitometer (RD514).

[0043]

As is apparent from the description of the examples, the reversible thermosensitive recording material of the present invention has a slippery layer on the printing layer, particularly a slipperiness mainly composed of silicone-modified urethane acrylate and electron beam curable polyurethane resin. By providing layers,
The abrasion resistance with the thermal head is improved to prevent surface scratches,
Also, the prevention of image breakage due to the prevention of head residue adhesion can be achieved. Furthermore, since the print layer is provided in the form of a heat-sensitive layer, the printability is improved.

[Brief description of 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.

Front page continuation (72) Inventor Nobuo Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (4)

[Claims] 1. A thermosensitive layer comprising a resin base material and an organic low-molecular substance dispersed in the resin base material as a main component on a support, and a transparent state and a cloudy state reversibly change depending on temperature. A reversible thermosensitive recording material having a printed layer on its surface, wherein a slipping layer is provided on the surface of the printed layer. 2. The reversible thermosensitive recording material according to claim 1, wherein the slipping layer is formed of a silicone-modified electron beam curable resin as a main component. 3. The slip layer is formed mainly of a silicone-modified electron beam-curable resin and an electron beam-curable resin having a polyester-based skeleton and having a branched molecular structure of five or more functional groups. The reversible thermosensitive recording material according to claim 1, wherein 4. The weight ratio of the electron beam curable resin having a branched molecular structure having 5 or more functional groups having a polyester skeleton to the silicone modified electron beam curable resin is 2: 8 to 7: 3.
The reversible thermosensitive recording material according to claim 3, wherein