JP2001071543A - Method for erasing print on reversible thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for printing and erasing on a reversible thermal recording medium by scanning it with laser light at a higher speed and obtaining high contrast of image. SOLUTION: A laser irradiating means outputs laser light 32 with intensity in the range of 2-10 W. Spot size of the laser light 32 on a reversible thermal recording medium is regulated to be smaller than 0.1 mm ϕ and printing is performed by scanning the surface of the reversible thermal recording medium at a speed of 600 mm/see or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for printing and erasing a reversible thermosensitive recording medium, and more particularly to a method for performing a high-speed printing and erasing process on a reversible thermosensitive recording medium by using a laser irradiation apparatus and obtaining a high image quality. The present invention relates to a printing and erasing method for a reversible thermosensitive recording medium capable of obtaining a high contrast.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a rewritable thermosensitive recording medium whose optical density changes reversibly based on the temperature at the time of application (hereinafter referred to as a reversible thermosensitive recording medium).
Or, on a irreversible thermosensitive recording medium, use a thermal head in which minute heating elements that generate heat by current are linearly integrated as a means for creating a visible image such as information recording,
A method is known in which a heating element at an arbitrary position is heated / cooled while contacting and scanning on a heat-sensitive recording medium to form a character or a visible image composed of minute points.

[0003] In the reversible thermosensitive recording layer, a color can be formed only by rapid cooling following heating.
Further, in order to perform the decoloring, it is sufficient that the cooling rate after heating is low. For example, when heating with a suitable heat source (such as a thermal head) for a relatively long time, not only the reversible thermosensitive recording layer but also the base material and the like disposed under the reversible thermosensitive recording layer are heated, so that the cooling rate is low and the phase separation state ( Erased state). On the other hand, after heating by an appropriate method, it is cooled rapidly by pressing a low-temperature metal block (hot plate, hot bar, etc.)
A colored state can be developed. In addition, at the time of printing using a suitable heat source exemplified, that is, a thermal head,
A so-called overwrite method in which writing is performed at the time of erasing or after erasing is also known.

Further, even when the thermal head is used for heating for an extremely short period of time, cooling (solidification) starts immediately after the completion of heating, so that a colored state can be developed. Therefore, even if the same heating temperature and / or the same heat source is used, the color development state and the decoloration state can be arbitrarily expressed by controlling the cooling temperature. As described above, in order to develop a coloring / erasing state on the reversible thermosensitive recording layer using the thermal head, an arbitrary portion is heated / cooled while the thermal head is in contact with and scanned on the reversible thermosensitive recording layer. By doing so, characters and visible images composed of minute points are formed.

Here, the heat generated from the thermal head is:
It is preferable that the thermal head is efficiently transmitted to the reversible thermosensitive recording layer, and it is necessary to bring the thermal head into close contact with the surface of the reversible thermosensitive recording medium at the time of scanning. (Thermal stress) is applied.

As an example, when the present invention is applied to a card as a reversible thermosensitive recording medium, the thickness of the card body becomes 188 to 188.
In the case of a PET card having a thickness of about 250 μm, 150 to 250 g / cm (1 to 1.5
kgf), and the thickness of the card body is about 760 μm.
In order to correct the warpage generated on the card surface during printing / erasing, a pressure of about 2 to 5 times is further applied.

[0007] The repetition durability of printing and erasing of a reversible thermosensitive recording medium is determined by the physical change of the protective layer or the reversible thermosensitive recording layer rather than the chemical change of the leuco dye and the developing colorant in the reversible thermosensitive recording layer. For example, when printing / erasing is repeatedly performed on the reversible thermosensitive recording layer by the above-described method, scratches are generated on the surface, and there is a problem in terms of durability against printing / erasing. was there.

Therefore, as a method of solving the above-mentioned problem caused by performing printing and erasing by bringing a heat medium such as a thermal head into contact with a reversible thermosensitive recording medium, a laser beam on a beam is applied to the recording medium. There is known a method in which a laser beam is turned on and off according to image information by scanning with focus, and a character or a visible image composed of minute points is formed in a non-contact manner by heat converted from the light.

A specific example of such a conventional technique is disclosed in Japanese Patent Application Laid-Open No. H11-151856, and is formed by appropriately laminating a support, a light-to-heat conversion layer, a reversible thermosensitive recording layer, and the like. The reversible thermosensitive recording medium is irradiated with a laser beam with variable irradiation light power by a laser recording device with variable irradiation light power to perform printing and erasing. The various conditions concerning laser light irradiation disclosed in the exemplified documents are as follows: when developing a color, the spot size of the laser light is 100 μmφ and the scan speed is 40 mm / sec.
c, When the intensity of the irradiation light is set to 50 to 200 mW and the obtained colored portion is decolorized, the intensity of the irradiation light is set to 20 to 100 mW.
mW.

The scanning speed of the laser beam on the reversible thermosensitive recording medium, that is, the scanning speed, is 40 to 50 m even in the prior art which is not exemplified here.
m / sec.

[0011]

Here, the situation in which a reversible thermosensitive recording medium is actually used in industry is mentioned as an example. For example, labeling of beer or the like, tag sheet of a container to be transported in a factory, etc. And erasing and printing on a card having a reversible thermosensitive recording layer by an automatic ticket gate. In these situations, it is required that the speed of printing and erasing the reversible thermosensitive recording medium by laser irradiation be further increased.

The present invention has been made in view of the above-mentioned problems and the above-mentioned social demands, and performs printing and erasing by scanning a reversible thermosensitive recording medium with a laser beam at a higher scanning speed. It is another object of the present invention to provide a method for erasing and printing a reversible thermosensitive recording medium capable of obtaining high image contrast.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, a laser irradiation means outputs a laser beam with an intensity in the range of 2 W to 10 W, and outputs the laser beam. Is adjusted so that the spot size on the reversible thermosensitive recording medium is less than 0.1 mmφ, and the laser beam is adjusted to 600 mm / s on the reversible thermosensitive recording medium.
The printing is performed by scanning at a speed of ec or more.

According to a second aspect of the present invention, in the first aspect of the present invention, the output intensity of the laser beam by the laser irradiation means is set in a range from 4 W to 8 W.

According to a third aspect of the present invention, in the first or second aspect, the scanning speed of the laser beam on the reversible thermosensitive recording medium is from 700 mm / sec to 1000 mm / sec.
It is characterized by the range up to sec.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the laser irradiation means outputs a laser beam with an intensity in a range of 0.1 W to 2 W,
The spot size of the laser light on the reversible thermosensitive recording medium is adjusted to be 0.1 mmφ or more, and the laser light is adjusted to 600 mm / sec on the reversible thermosensitive recording medium.
It is characterized in that printing is erased by scanning at a lower speed.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the output intensity of the laser beam by the laser irradiation means is set in a range from 0.1 W to 1.0 W.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

The reversible thermosensitive recording medium on which printing or erasing is performed by the method for printing / erasing a reversible thermosensitive recording medium according to the present invention will be described. The reversible thermosensitive recording medium has a reversible thermosensitive recording layer on a support such as a card substrate, and is formed by applying a reversible thermosensitive recording material on the support,
A protective layer is formed thereon, or a reversible thermosensitive recording transfer sheet is prepared and transferred to a support, or a reversible thermosensitive recording adhesive sheet is prepared and bonded to a support. There is the one manufactured by the method of (1). FIG.
FIG. 1 is a structural cross-sectional view showing an embodiment of a reversible thermosensitive recording transfer sheet for producing a reversible thermosensitive recording medium according to a first embodiment of the present invention.

As shown in FIG. 1, this reversible thermosensitive recording transfer sheet has an adhesive layer 11 for bonding to a card substrate or the like by a hot press or the like, a barrier layer 12, and a reversible information by heating. Reversible thermosensitive recording layer 13 containing a leuco dye as a main component which can be recorded and erased
And a protective layer 14 for protecting the surface of the reversible thermosensitive recording layer 13, a release layer 15 for releasing the protective layer 14 from the base material 16, and easy production and management of the reversible thermosensitive recording transfer sheet. And a base material 16.

Next, each layer shown in FIG. 1 will be described in more detail. First, the adhesive layer 11 only needs to be capable of sufficiently bonding when the reversible thermosensitive recording transfer sheet is hot-pressed on a card or the like, and generally used polyester resins, alkyd resins, vinyl resins, A polyurethane resin or a mixed resin thereof can be used. The barrier layer 12 is for preventing the reversible thermosensitive recording layer from being inadvertently colored by a resin having a large number of polar groups contained in the adhesive layer or a solvent used during coating, and is preferably an ultraviolet curable type. It can be formed by applying a resin paint.

The reversible thermosensitive recording layer 13 is a layer capable of reversibly recording and erasing information by heating with, for example, a thermal head or the like.

The reversible thermosensitive recording layer 13 is a layer composed mainly of a leuco dye, a color-reducing agent and a binder resin, and reversibly repeats coloring / decoloring by heat. Leuco dyes are generally referred to as colorless or pale color electron-donating dye precursors. Further, the color-reducing agent is called an electron-accepting compound, and causes a reversible color change in the dye precursor due to a difference in cooling rate after heating, and is an aliphatic hydrocarbon having 6 or more carbon atoms. A phenolic compound or a phthalic acid compound having at least one group, or an acidic compound having a phenolic hydroxyl group and an amino group is used.

The leuco dyes contained in the reversible thermosensitive recording layer 13 as main components include crystal violet lactone, 3-indolino-3-p-dimethylaminophenyl-6-dimethylaminophthalide, and 3-diethylamino. -7-chlorofluoran, 2- (2-chlorophenylamine) -diethylaminofluoran, 2-
(2-fluorophenylamino) -6-diethylaminofluoran, 2- (2-fluorophenylamino) -6
-Di-n-butylaminofluoran, 3-diethylamino-7-cyclohexylaminofluoran, 3-diethylamino-5-methyl-7-t-butylfluoran, 3
-Diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-p-butylanilinofluoran, 3-cyclohexylamino-6
Chlorofluorane, 2-anilino-3-methyl-6
(N-ethyl-p-toluidino) -fluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-
Pyrrolidino-7-cyclohexylaminofluoran, 3
-N-methylcyclohexylamino-6-methyl-7-
Anilinofluoran, 3-N-ethylpentylamino-
6-methyl-7-anilinofluoran and the like can be mentioned.

The colorless or pale-color electron-donating dye precursors as leuco dyes may be used alone or in combination of two or more.

Further, as the color-reducing agents contained as a main component in the reversible thermosensitive recording layer 13, N- (p-hydroxyphenyl) -N'-n-octadecylthiourea, N-
(P-hydroxyphenyl) -N'-n-octadecylurea, N- (p-hydroxyphenyl) -N'-n-octadecylthioamide, 4'-octadecaneanilide,
2-octadecyl terephthalic acid, N-octadecyl (p
-Hydroxyphenyl) amide, N- (p-hydroxybenzoyl) -N-octadecanoylamine, N- [3
-(P-hydroxyphenyl) propiono] -N'-octadecanohydretide, N-[(p-hydroxyphenyl) methyl] -n-octadecylamide, N-[(p-
[Hydroxyphenyl) methyl] -n-octadecylurea, N-[(p-hydroxyphenyl) methyl] -N '
-N-octadecyl oxamide and the like.

Here, the developer may be used alone or in combination of two or more.

The binder resin contained in the reversible thermosensitive recording layer 13 includes starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylamide. / Acrylic ester copolymer,
Water-soluble polymers such as acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, polyvinyl acetate, Latexes such as polyurethane, polyacrylate, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, and the like, especially electron donating dyes A reversible thermosensitive recording layer with excellent dispersibility of the precursor (leuco dye) and electron-accepting compound (color-reducing agent) and excellent rewriting durability is obtained, so double bonds are introduced into the thermoplastic resin molecule. UV-curable or electron-beam curable resin, vinyl chloride / vinyl acetate / vinyl alcohol copolymer Resin obtained by ester polymer of acrylic acid or methacrylic acid can be used to. These resins can be used alone or in combination of two or more.

Such a reversible thermosensitive recording layer 13 has the property of developing color by rapid cooling following heating, and decoloring when the cooling rate after heating is low. For example, when heating with a suitable heat source (laser light or the like) for a relatively long time, not only the reversible thermosensitive recording layer 13 but also the surrounding area is heated, so that the cooling rate is low, and the phase separation state (decolored state)
On the other hand, after heating by an appropriate method, by rapidly cooling by pressing a low-temperature metal block or the like, or by heating for a very short time using a thermal head or laser light, etc., after heating is completed It has a property that a color development state can be developed by immediately starting cooling (solidification).

Here, the reversible thermosensitive recording layer 13 is about 3 to 1
It is formed to a thickness of 5 μm.

The protective layer 14 shown in FIG. 1 contains an ultraviolet curable resin in order to make the hardness sufficient. Further, appropriate irregularities are formed on the surface of the protective layer 14 to prevent glare on the surface of the protective layer.
In order to prevent the generation of scratches on the surface and to provide the self-cleaning property of the thermal head, the protective layer 14 preferably contains silica.

The peeling layer 15 shown in FIG. 1 is for improving the peeling performance between the base material 16 and the protective layer 14. Therefore, the peeling layer 15 is made of a fluorine-based resin or various kinds of resin. Wax, a coating layer of a coating agent added to a vehicle such as an acrylic resin, a cellulose resin, a vinyl resin, or the like with a release agent such as silicone,
Fluorine resin, silicon, melamine resin, polyolefin resin, ionizing radiation cross-linkable polyfunctional acrylate,
It consists of a coating layer of a coating agent with a releasable resin such as a resin such as polyester or epoxy, or an extrusion coat layer.

The substrate 16 shown in FIG. 1 is made of a synthetic resin sheet such as polyethylene terephthalate (PET), polyacetate, polystyrene (PS), epoxy resin, polyvinyl chloride (PVC) and polycarbonate (PC). Synthetic paper or the like can be used. The thickness of the substrate 11 is usually about 10 to 50 μm.

FIG. 2 is a structural sectional view showing an embodiment of a reversible thermosensitive recording transfer sheet for producing a reversible thermosensitive recording medium according to the second embodiment of the present invention.

As shown in FIG. 2, this reversible thermosensitive recording transfer sheet has a concealing layer 22 between a barrier layer 23 and an adhesive layer 21 as a different configuration from the first embodiment. . When the slit is formed in the reversible thermosensitive recording medium and cut, the concealing layer 22 adheres the leuco dye generated from the reversible thermosensitive recording layer 24 to the adhesive layer, and the adhesive layer 21 to which the leuco dye adheres is formed. When hot pressing,
This is a layer for concealing irreversible coloring on the adhesive layer 21 caused by the reaction between the leuco dye and the adhesive layer 21.

As an embodiment, the concealing layer 22 is formed by coloring with metal particles such as aluminum paste or metal oxide particles such as titanium oxide, or the adhesive layer which is separated in the state shown in FIG. When the functions of the opaque layer 21 and the concealing layer 22 are combined to form a concealing adhesive layer, or a second barrier layer is formed as a concealing layer, and metal vapor deposition is performed on the barrier layer to conceal the irreversible color formation. In some cases, a layer is formed.

Here, the metal particles contained in the concealing layer and the concealing adhesive layer include aluminum, zinc or copper, and the metal oxide particles include titanium oxide, zinc oxide and the like. These can be used in a state of being dispersed in a resin solution, and are coated to form a concealing layer. When a metal vapor deposition layer is used as the concealing layer, aluminum, zinc, copper, nickel, gold, silver, tin, or the like is formed by vapor deposition.

In particular, when a concealing layer is formed by coloring with metal particles of an aluminum paste or when a metal deposition layer is formed as a concealing layer using aluminum, the concealing layer also has a function as a laser reflection layer. be able to.

Further, a single laser reflection layer can be provided between the concealing layer 22 and the barrier layer 23. As a specific embodiment, the specular glossiness is 50% or more (Gs (6
0) = 50%).

When the concealing layer 22 contains metal particles or metal oxide particles, the barrier layer 23 may be inadvertently formed by the reversible thermosensitive recording layer 24 from a solvent or a resin component used for coating the concealing layer 22. It prevents color formation, and when the concealing layer 22 is a metal-deposited layer, it is difficult to use an acid such as a resin having a large number of polar groups contained in the adhesive layer 21 or a color-reducing agent contained in the reversible thermosensitive recording layer 24. Concealing layer 22 made of a material having a base
Is prevented from being corroded, and can preferably be formed by applying an ultraviolet curable resin paint.

However, in the present invention, the leuco dye detached from the reversible thermosensitive recording layer 24 when the reversible thermosensitive recording transfer sheet is divided by forming slits or the like adheres to the adhesive layer, Is intended to improve the visibility of information recorded in the reversible thermosensitive recording layer 24 by concealing irreversible coloring that occurs when the adhesive layer 21 to which is adhered is heated. The configuration is not limited to the above configuration, and other concealing layers 22 suitable for the above purpose can be used as appropriate.

As another example, for example, a metal particle or a metal oxide particle is contained in the ultraviolet-curable resin coating material constituting the barrier layer 23, and the reversible thermosensitive recording layer 24 and the adhesive layer 21 are provided between the reversible thermosensitive recording layer 24 and the adhesive layer 21. It may be formed.
By doing so, it is possible to prevent the reversible thermosensitive recording layer 24 from being inadvertently colored by the resin having a large number of polar groups contained in the adhesive layer 21 and to prevent the leuco dye attached to the adhesive layer 21 from being colored. Irreversible coloring when heated and pressed can be prevented, and the coating process can be simplified.

Accordingly, in the reversible thermosensitive recording transfer sheet having the structure shown in FIG. 2, when the adhesive layer 21 and the leuco dye react between the adhesive layer 21 and the reversible thermosensitive recording layer 24 by hot pressing. Since the concealing layer 22 for concealing the irreversible color formation is formed, even when information is recorded on the reversible thermosensitive recording layer 24, it is possible to prevent the visibility from being lowered.

Examples of the reversible thermosensitive recording adhesive sheet include lamination examples of an adhesive layer / substrate / reversible thermosensitive recording layer / protective layer /, between the adhesive layer and the base material or between the base material and the reversible thermosensitive recording layer. Between the concealing layer and the reversible thermosensitive recording layer, a barrier layer may be formed. The materials of these layers are the same as those of the reversible thermosensitive recording adhesive sheet described above.

The reversible thermosensitive recording medium according to the present invention is produced by transferring or adhering the reversible thermosensitive transfer sheet or the reversible thermosensitive recording adhesive sheet to a support such as a card substrate and heat-sealing the same. And a coating prepared by applying a coating for a reversible thermosensitive recording layer on a support such as a card substrate.

As a support such as a card base material, a sheet made of the following material or a laminate thereof is used.

Chlorine-containing polymer: polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-
Vinyl alcohol copolymer, vinyl chloride-vinyl acetate-
Polyester resins such as maleic acid copolymer, vinyl chloride-acrylate copolymer, polyvinylidene chloride, vinylitene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer; polyethylene terephthalate resin (PET), polybutylene terephthalate resin (P
A biodegradable plastic resin such as BT) or a condensed ester resin of an acid component such as terephthalic acid or isophthalic acid and an alcohol component such as ethylene glycol or cyclohexanedimethanol (for example, PETG: a trademark of Eastman Chemical Company); Lactic acid-based resin, natural polymer-based resin composed of starch and modified polyvinyl alcohol, microbial resin composed of β-hydroxybutyric acid and β-hydroxyvaleric acid, etc., as well as polyacetate, polystyrene (PS), epoxy resin ,
Polyvinyl chloride (PVC) and polycarbonate (P
C), a synthetic resin sheet such as a polyamide resin, an acrylic resin, and a silicone resin, or a synthetic paper. These materials may be appropriately combined, or a laminate of these materials may be used. The thickness of these sheets is typically 1
It may be about 0 to 50 μm.

As an example of such lamination, a core sheet in which two white polyvinyl chloride resin sheets (for example, having a thickness of 280 μm) printed on the surface are laminated, and a front and back surface of the core sheet (for example, A core sheet in which a transparent polyvinyl chloride resin sheet (thickness of 100 μm) is laminated as an oversheet, a core sheet in which two white PETG sheets (for example, 280 μm thickness) on the surface of which are printed or the like are laminated, and this core sheet (For example, thickness 1
(00 μm) transparent PETG sheet laminated as an oversheet.

Next, a more detailed embodiment of a reversible thermosensitive recording medium which performs printing or erasing by the method of printing / erasing a reversible thermosensitive recording medium according to the present invention will be described with reference to the drawings.

<First Embodiment> Substrate 16 25 μm thick transparent polyethylene terephthalate (PE
T. Toyobo Co., Ltd. product name E5100) was prepared.

2. Release layer 15 The base material 17 was prepared by using a material having the following composition with a # 4 wire bar.
Apply on the surface, dry (120 ° C, 2 minutes)
Formed.・ Silicone resin (Shin-Etsu Chemical Co., Ltd., trade name KS-
882) 40 parts by weight ・ Polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd.
4 parts by weight of brand name BL-1)-Hardener (manufactured by Shin-Etsu Chemical Co., Ltd., trade name CAT-PS)
-80) 1 part by weight ・ Solvent (methyl ethyl ketone: toluene = 1: 1) 6
00 parts by weight

3. Protective layer 14 A material having the following composition is placed in a container, zirconia beads having a diameter of 2 mm are added, and the mixture is dispersed with a paint shaker for 10 minutes to obtain a paint. The paint is applied on the release layer 31 with a # 7 wire bar, and dried. (100 ° C., 2 minutes) and ultraviolet irradiation (160 W / cm 3 lamp, 25 m / min, 1 pass), and then formed into a dry film thickness of 3 μm.・ Ultraviolet curable paint (Dainippon Ink and Chemicals Co., Ltd.)
20 parts by weight (trade name: Unidick 17-806) Silica (Mizukasil P, manufactured by Mizusawa Chemical Industry Co., Ltd.)
-603) 1 part by weight ・ Solvent (methyl ethyl ketone: toluene = 1: 1) 3
0 parts by weight

4. Reversible thermosensitive recording layer 13 A material having the following composition is put in a container, zirconia beads having a diameter of 2 mm are added, and the mixture is dispersed with a paint shaker for 60 minutes to obtain a coating material. The coating material is coated on the protective layer 29 with a # 26 wire bar. After drying (80 ° C., 5 minutes) and irradiating with ultraviolet rays (160 W / cm, 25 m / min, 1 pass),
It was formed to a dry film thickness of 6 μm. -Leuco dye (3-diethylamino-6-methyl-7-
Anilino Fluoran, manufactured by Yamamoto Kasei Co., Ltd., trade name OD
B) 20 parts by weight ・ Sensitive color reducing agent (N- (4-hydroxyphenyl) -N′-
n-octadecyl urea, JP-A-6-210954) 6
0 parts by weight Thermoplastic resin (acrylic resin, Mitsubishi Rayon Co., Ltd.)
(Trade name: Dianal BR-80) 60 parts by weight ・ Ultraviolet curable resin (trade name: LASF, manufactured by BASF Corporation)
ROMER LR8864) 20 parts by weight Photopolymerization initiator (manufactured by Ciba Geigy Co., Ltd., trade name: Darocur 1173) 1 part by weight Solvent (MEK: toluene = 1: 1) 1000 parts by weight

5. Barrier layer 12 A material having the following composition is used as a paint, coated on the reversible thermosensitive recording layer 27 with a # 20 wire bar, and dried (80
° C, 5 minutes), UV irradiation (160W / cm, 25m
/ Min, 1 pass) to form a dry film thickness of 10 μm.・ Ultraviolet curable paint (Dainippon Ink and Chemicals Co., Ltd.)
Brand name Unidick C3-374) 1 part by weight ・ Solvent (toluene) 1 part by weight

6. Adhesive Layer 11 A paint having the following composition was applied on the concealing layer 23 with a # 10 wire bar, and dried (80 ° C., 5 minutes) to form a dry film thickness of 3 μm. -Deformed ether type polyester adhesive (manufactured by FUJIFILM Corporation, trade name: Stafix SOC-30-M)
2 parts by weight ・ Solvent (methyl ethyl ketone: toluene = 1: 1) 1
Parts by weight

Next, the manufacturing process when the reversible thermosensitive recording transfer sheet having the above structure is divided and applied to a card or the like will be described below. However, as a card substrate for transferring a reversible thermosensitive recording medium, a transparent rigid polyvinyl chloride sheet /
A laminate of white rigid polyvinyl chloride sheet / white rigid polyvinyl chloride sheet / transparent rigid polyvinyl chloride sheet is used.

7. Forming a slit A slit is formed in a reversible thermosensitive recording medium to divide it into a desired width.

8. Thermal Transfer The split reversible thermosensitive recording transfer sheet having the above structure is transferred by pressing a rubber roll heated to 100 ° C. on a transparent rigid vinyl chloride sheet having a thickness of 100 μm, and the base material 16 is peeled off.

9. Thermal bonding 8. A transparent hard vinyl chloride sheet on which a reversible thermosensitive recording layer is formed, two printed hard rigid vinyl chloride sheets having a thickness of 280 μm and a transparent hard vinyl chloride sheet having a thickness of 100 μm, which are overlapped with each other, At 135 ° C. under a pressure of 50 kg / cm 2 for 10 minutes.

10. Punching process 9. Then, the sheet obtained by performing the heat bonding in the above step is punched out with a mold to the outer shape specified in JISX6301, to obtain a card as a reversible thermosensitive recording medium.

11. As shown in FIG. 3, the laser light 3 with variable irradiation light power is applied to the reversible thermosensitive recording medium manufactured in the above process by the laser irradiation device 31 with variable irradiation light power.
Irradiate 2 to erase the print. The laser irradiation device used in the present invention may be a scanning laser capable of obtaining an output of 0.2 W or more, and specific examples include a carbon dioxide laser, a carbon monoxide laser, a semiconductor laser, a YAG laser,
An excimer laser and the like are mentioned, and a carbon dioxide gas laser or a YAG laser is preferably used. In the present embodiment, Keyence ML-91 is used as a laser irradiation device.
Using 00, a CO ₂ laser having a wavelength of 10.6 μm is irradiated.

12. Further, as a condition relating to the printing process in the present invention, the spot size of the laser beam is 0.1
scan speed is 600m
m / sec or more, preferably 700 to 1
000 mm / sec, and the intensity of the laser beam is 2
The power may be 10 to 10 W, preferably 4 to 8 W.
On the other hand, as the decoloring condition, the spot size of the laser beam may be 0.1 mmφ or more, preferably 0.1 mmφ.
~ 2.0mmφ, scan speed is 600mm
/ Sec, preferably 100 to 50
0 mm / sec, and the intensity of laser light is 0.1 to
It may be in the range of 2W, preferably 0.2 to 1.0.
W range.

In this embodiment, the spot size of the laser beam is 0.01 mmφ, and the scan speed is 800 mm.
mm / sec, the intensity of the laser beam is 7 W, and the spot size of the laser beam is 0.2 mm.
φ, scan speed 250 mm / sec, laser light intensity 0.6 W.

<Second Embodiment> As described above, the second embodiment
The configuration of the reversible thermosensitive recording medium used in the embodiment is different from the configuration of the reversible thermosensitive recording medium in the first embodiment in that the barrier layer 23 and the adhesive layer 21 The difference lies in that the concealing layer 22 is disposed between them. In the present embodiment, details of each of the other layers are the same as those in the first embodiment,
Here, only the concealing layer 22 is shown in detail.

1. Hidden layer 22 A material having the following composition was stirred with a stirrer for 30 minutes to form a paint, coated on the barrier layer 23 with a # 10 wire bar, dried (80 ° C, 5 minutes), and dried to a thickness of 3 µm.
Formed. 9 parts by weight of aluminum paste (manufactured by Asahi Kasei Kogyo Co., Ltd., trade name: MH8803) 11 parts by weight of vinyl chloride / vinyl acetate / maleic anhydride copolymer (manufactured by Union Carbide Co., Ltd., trade name: VMCH) ・ Solvent (methyl ethyl ketone: toluene) = 1: 1) 4
0 parts by weight

Also, in the step of forming on the card base material in the second embodiment, 7. To 10. The description is omitted because it is the same as the above steps.

2. Next, the reversible thermosensitive recording medium manufactured in the same process as that of the first embodiment is irradiated with laser light by a laser irradiation device to perform printing erasure. The same conditions as in the first embodiment are used, and printing and erasing are performed under the same conditions.

In this embodiment, the spot size of the laser beam is 0.01 mmφ, and the scan speed is 800 mm.
mm / sec, the intensity of the laser light is 4.5 W, and
As the erasing condition, the spot size of the laser beam was set to 0.2.
mmφ, the scanning speed is 250 mm / sec, and the intensity of the laser beam is 0.4 W.

<Comparative Example 1> Next, as Comparative Example 1 for comparing the effects of the first embodiment, a reversible thermosensitive recording medium having the same configuration as that used in the first embodiment was employed. did.

Also, in the forming step for the card base material in the comparative example 1, the method of the first embodiment described in the paragraph 7. To 10. The description is omitted because it is the same as the above steps.

Printing and erasing are performed on the reversible thermosensitive recording medium manufactured in the above steps. In Comparative Example 1, this processing is performed using a thermal head. The conditions relating to the print erasing process are as follows: the head density of the thermal head to be used is 8 dots / mm, and the pressing of the thermal head against the reversible thermosensitive recording medium is 1200 g / c.
m, the energy which the thermal head gives to the reversible thermosensitive recording medium when printing on the reversible thermosensitive recording medium is 0.7
The energy applied by the thermal head to the reversible thermosensitive recording medium when erasing a printed portion on the reversible thermosensitive recording medium is set to 0.44 mJ / dot.

Comparative Example 2 As a comparative example 2 for comparing the effects of the second embodiment, a reversible thermosensitive recording medium having the same configuration as that used in the second embodiment was employed. .

Similarly, in the process of forming the card base material in Comparative Example 2, the description is omitted because it is the same as that of the second embodiment.

Similarly, in Comparative Example 2, printing and erasing are performed using a thermal head on the reversible thermosensitive recording medium manufactured in the above-described steps, but the printing is performed under the same conditions as in Comparative Example 1. .

Here, the print erasure processing in the first and second embodiments of the present invention and the comparative examples 1 and 2 is repeated 100 times, respectively, and the first embodiment and the comparative examples 1 and 2 are repeated.
FIG. 4 shows a comparison of the results obtained by measuring the print / erase density with the Macbeth densitometer for the embodiment of the present invention and Comparative Example 2.

As is clear from FIG. 4, when the first embodiment and the comparative example 1 using the same medium are compared, and the second embodiment and the comparative example 2 are compared, the print density of the embodiment of the present invention is higher. And improved results in the erase density. The reason is that heating at an instantaneously high temperature is an ideal printing process from heating to quenching. Since the laser power is low and the heating time is long, it is considered that the printing density is lower than in the present invention.

The first and second embodiments of the present invention shown in FIG.
The results in the embodiment are comparable to the results printed by various conventional print erasing methods proposed for the purpose of improving the quality of a printed image.

As a result that can be visually confirmed, both of the first and second embodiments show good print conditions without any problem, whereas both of the comparative examples 1 and 2 have good print conditions. The characters were legible but had many scratches.

[0079]

As is apparent from the above description, according to the present invention, printing and erasing are performed by scanning a reversible thermosensitive recording medium with a laser beam at a higher scan speed than in the prior art. Even after a plurality of print erasures, it is possible to obtain a high image contrast comparable to that of the prior art for improving the quality of a printed image.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of a reversible thermosensitive recording medium used in a first embodiment of the present invention.

FIG. 2 is a cross-sectional configuration diagram showing an embodiment of a reversible thermosensitive recording medium used in a second embodiment of the present invention.

FIG. 3 is a diagram schematically illustrating a method of erasing a print on a reversible thermosensitive recording medium according to the present invention.

FIG. 4 is a diagram comparing the results of measuring the print erase density using a Macbeth densitometer for the first embodiment of the present invention and Comparative Example 1, and for the second embodiment and Comparative Example 2.

FIG. 5 is a diagram schematically illustrating a method of erasing print on a reversible thermosensitive recording medium according to a conventional technique.

[Explanation of symbols]

 11, 21 Adhesive layer 22 Concealing layer 12, 23 Barrier layer 13, 24 Reversible thermosensitive recording layer 14, 25 Protective layer 15, 26 Release layer 16, 27 Base material 31 Laser irradiation device 32 Laser light

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Morinaka 4- 14-12 Koishikawa, Bunkyo-ku, Tokyo Joint printing company (72) Inventor Junhei Nakagawa 4- 14-12 Koishikawa, Bunkyo-ku, Tokyo Joint Within Printing Co., Ltd. (72) Inventor Mabi Nakanishi 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Joint printing Co., Ltd. F-term (reference) 2C065 AB01 AD02 AF01 CA03 CA08 CA13 2H026 AA09 AA24

Claims (5)

[Claims] 1. A laser irradiation means for outputting a laser beam with an intensity in a range of 2 W to 10 W, and adjusting a spot size of the laser beam on a reversible thermosensitive recording medium to be less than 0.1 mmφ. The laser beam is irradiated on the reversible thermosensitive recording medium by 60
A print erasing method for a reversible thermosensitive recording medium, wherein printing is performed by scanning at a speed of 0 mm / sec or more. 2. The method according to claim 1, wherein an output intensity of the laser beam by the laser irradiating means is in a range of 4 W to 8 W. 3. The scanning speed of the laser light on the reversible thermosensitive recording medium is from 700 mm / sec to 1000 mm.
3. The method according to claim 1, wherein the printing time is up to mm / sec. 4. A laser irradiation means for applying a laser beam of 0.1 W
The laser beam is output at an intensity in the range from 1 to 2 W, and the spot size of the laser light on the reversible thermosensitive recording medium is adjusted to be 0.1 mmφ or more.
4. The print erasing method for a reversible thermosensitive recording medium according to claim 1, wherein the print is erased by scanning at a speed of less than 0 mm / sec. 5. The method according to claim 4, wherein the output intensity of the laser beam by the laser irradiating means is in a range of 0.1 W to 1.0 W.