JP3388415B2 - Manufacturing method of thermal recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heat-sensitive recording medium, and particularly to improve the appearance by printing,
The present invention relates to a method for producing a thermal recording medium which is excellent in durability, abrasion resistance and heat resistance and can perform good recording.

[0002]

2. Description of the Related Art In various cards such as ID cards and prepaid cards, heat-sensitive recording is performed for displaying balance and the like in addition to magnetic recording. Thermal recording is widely used because it does not require development, has a high color density, and is inexpensive. In such a thermal recording type card,
For example, a heat-sensitive recording layer is provided on one surface of a base material, and the heat-sensitive recording layer is colored by heating with a thermal head or the like to display desired characters and the like.

In order to protect the surface of such a heat-sensitive recording layer and provide it with chemical resistance, a protective layer is usually provided. Further, since the components contained in the protective layer may cause the thermal recording layer to develop color, an intermediate layer is provided between the thermal recording layer and the protective layer in order to prevent this. The fogging phenomenon can be prevented by this intermediate layer.

However, since the intermediate layer and the protective layer are conventionally formed by offset printing, it is necessary to use an ink having offset printing suitability, such as solvents, reactive diluents, various additives and pigments. There were restrictions on the addition. Therefore, there is a restriction on the coating material that can be used for the protective layer, and an effective protective layer cannot be formed.

Further, since the intermediate layer and the protective layer are formed by offset printing, it is necessary to contain wax, an unreactive resin component or the like in order to have printability, and when printing with a thermal head, heating is required. Since these components elute, the thermal head becomes dirty and causes the print surface to be scratched.

Further, since the intermediate layer and the protective layer are formed by offset printing, pinholes are apt to be generated in these layers, and therefore, the heat-sensitive recording layer may be colored or erased by chemicals penetrating through the pinholes. was there.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the applicant of the present invention has applied a material containing an ultraviolet curable resin to the intermediate layer and the protective layer according to Japanese Patent Application No. 5-121880, and irradiates with the ultraviolet rays. Then, by curing this, a thermal recording medium excellent in durability, abrasion resistance, heat resistance and chemical resistance, and a method for manufacturing the same were proposed.

By the way, it is desired to provide a printing layer in order to improve the appearance and to give visible information even in such a thermal recording medium.

However, the above-mentioned Japanese Patent Application No. 5-1218.
When the printing layer is formed on the protective layer after providing the protective layer according to No. 80, in order to prevent the hands and dirt from adhering to the surface of the card, silicone oil or silicone should be added to the paint forming the protective layer. Since a resin or the like is added, there is a problem in that even if a print layer is formed on the protective layer cured by ultraviolet irradiation, the adhesion is poor and the print layer peels off.

Further, it is conceivable to form the protective layer after forming the printed layer in order to improve the adhesion of the printed layer. In this case, coating of a material containing an ultraviolet curable resin for forming the protective layer. Is usually performed on a base material in a roll state, whereas printing for forming a print layer is usually performed on a base material in a sheet state. Therefore, it was difficult to perform printing for the base material cut into a sheet to form a print layer and then perform coating for forming the protective layer.

The present invention solves the above problems,
An object of the present invention is to provide a method for producing a heat-sensitive recording medium which forms a printing layer to improve the appearance and is excellent in durability, abrasion resistance, heat resistance and chemical resistance and can perform good recording.

[0012]

According to the present invention, a method for producing a thermosensitive recording medium having a thermosensitive recording layer, a protective layer for the thermosensitive recording layer, and a printing layer on the protective layer is provided on a substrate. A step of coating a heat-sensitive recording material on the heat-sensitive recording layer to form a heat-sensitive recording layer, and coating a material containing a UV-curable resin on the heat-sensitive recording layer to remove the C--C double bond in the infrared spectral curve of the UV-curable resin. The step of forming a protective layer by irradiating ultraviolet rays having an area of a peak representing 30% to 80% relative to 100% before ultraviolet irradiation, and a printing layer containing an ultraviolet curable resin on the protective layer. It has a step of printing and a step of completely curing the protective layer and the printed layer by irradiation with ultraviolet rays.

According to the present invention, a method for producing a thermosensitive recording medium having a thermosensitive recording layer, a protective layer for the thermosensitive recording layer, a printing layer on the protective layer, and a printing protective layer is provided on a substrate. A step of coating a heat-sensitive recording material to form a heat-sensitive recording layer, and coating a material containing an ultraviolet-curable resin on the heat-sensitive recording layer, and showing a C—C double bond in an infrared spectral curve of the ultraviolet-curable resin A step of forming a protective layer by irradiating ultraviolet rays having a peak area of 30 to 80% relative to 100% before ultraviolet irradiation, and printing with an ink containing an ultraviolet curable resin on the protective layer. The area of the peak representing the C—C double bond in the infrared spectroscopic curve of the ultraviolet curable resin is 30% to 80% relative to that before the ultraviolet irradiation, and the printing layer is irradiated with the ultraviolet light. Forming process and marking On the layer, the ink containing an ultraviolet curable resin is printed, forming a print protective layer, by ultraviolet irradiation, the protective layer, and a step of completely curing the printed layer and the print protecting layer. In the above method, the process is performed on the base material in a roll state up to the step of forming the protective layer, and is performed on the base material in the sheet state after the step of forming the print layer.

[0014]

Embodiments of the method for manufacturing a thermal recording medium according to the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows a thermal recording medium manufactured according to the present invention. The thermosensitive recording medium produced according to the present invention has a thermosensitive recording layer 1 on a substrate 12 as shown in FIG.
4, the intermediate layer 16, the protective layer 18, the printing layer 20, and the printing protective layer 22 are sequentially stacked.

As the base material 12, for example, a synthetic resin sheet such as polyethylene terephthalate (PET), polyacetate, polystyrene (PS), epoxy resin, polyvinyl chloride (PVC) and polycarbonate (PC) or a synthetic paper is used. it can. The thickness of the base material 12 is usually about 100 to 300 μm.

The material constituting the thermal recording layer 14 is
A heat-sensitive recording material used for ordinary heat-sensitive recording performed by a thermal head or the like is used. Such a thermosensitive recording material is mainly composed of a polymer binder and a thermosensitive coloring material. As the polymer binder, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, starch, styrene-maleic acid copolymer, polymethylmethacrylate, homopolymer or copolymer of methacrylic resin such as polyethylmethacrylate, polystyrene, Acrylic-styrene copolymer, polyester resin, coumarone resin, ABS resin, nitrocellulose, etc. can be used.

The thermosensitive coloring material is a combination of a developer having a phenolic hydroxyl group and a colorless leuco dye, and 4,4'-isopropylidenephenol, benzyl-p-hydroxybenzoate is used as a developer. 4,
4′-dihydroxy-3,5′-diallyldiphenyl sulfone, methyl-bis (hydroxyphenyl) acetate, gallic acid ester, p-phenylphenol and the like can be mentioned. As leuco dyes, crystal violet lactone, 3-indolino-3-p-dimethylaminophenyl-6-dimethylaminophthalide, 3-diethylamino-7-chlorofluorane, 2- (2-chlorophenylamine) -diethylaminofluorane. , 2- (2-
Fluorophenylamino) -6-diethylaminofluorane, 2- (2-fluorophenylamino) -6-di-
n-Butylaminofluorane, 3-diethylamino-7
-Cyclohexylaminofluorane, 3-diethylamino-5-methyl-7-t-butylfluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3
-Diethylamino-6-methyl-7-p-butylanilinofluorane, 3-cyclohexylamino-6-chlorofluorane, 2-anilino-3-methyl-6- (N-ethyl-p-toluidino) -fluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-pyrrolidino-7-cyclohexylaminofluorane, 3-N-methylcyclohexylamino-6-methyl-7-anilinofluorane, 3-N-ethyl Mention may be made of pentylamino-6-methyl-7-anilinofluorane and the like.

The thermal recording layer 14 is formed to have a thickness of 3 to 5 μm.

The heat-sensitive recording layer 14 is preferably formed of a reversible heat-sensitive recording material rather than the above-mentioned irreversible heat-sensitive recording material. The reversible thermosensitive recording material comprises a resin such as polyester and an organic low-molecular substance dispersed in the resin, as described in JP-A-57-109695 and JP-A-2-187389. ing. In the reversible thermosensitive recording material, the transparency changes because the refractive index of the organic low molecular weight substance becomes equal to or different from that of the resin by selecting the heating temperature. That is, as shown in FIG.
If it is below 0 and it is cloudy, the temperature T1
After heating to ~ T2, cool to below T0 (arrow A)
Then, the refractive index of the organic low molecular weight substance becomes substantially equal to that of the resin, so that the reversible thermosensitive recording layer changes to a transparent state.

Furthermore, when this is heated to a temperature of T3 or higher and then cooled to a temperature of T0 or lower (arrow B), the organic low-molecular substance has a refractive index different from that of the resin, causing light scattering, and reversible heat sensitivity. The recording layer changes to a cloudy state again.

Further, the reversible thermosensitive recording layer is formed at temperatures T0 to T
When heated to 1 or T2 to T3 and then cooled to a temperature of T0 or lower (arrow C or D), the reversible thermosensitive recording layer is in a state between transparent and cloudy.

The reversible thermosensitive recording material can repeat such a state change.

To give an example of T0 to T3, the temperatures are 60 ° C., 70 ° C., 80 ° C. and 110 ° C., respectively.

The resin used in the reversible thermosensitive recording material is preferably a resin having good transparency, excellent mechanical strength and good film-forming property. Specific examples thereof 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. , Polyvinylidene chloride, vinylidene chloride-
Examples thereof include vinyl chloride copolymers, vinylidene chloride-acrylonitrile copolymers, polyester resins, polyamide resins, acrylic resins and silicone resins. Of these, particularly preferred are vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer,
Vinyl chloride-vinyl acetate-vinyl alcohol copolymer,
Polyester resin is applicable.

As the organic low molecular weight substance, alkanol,
Alkane diol, halogen alkanol or halogen alkane diol, alkylamine, alkane, alkene, alkyne, halogen alkane, halogen alkene, halogen alkyne, cycloalkane, cycloalkene, cycloalkyne, saturated or unsaturated mono- or dicarboxylic acid or ester thereof, Amides, or ammonium salts, saturated or unsaturated halogen fatty acids or their esters, amides, or ammonium salts, acrylic carboxylic acids or their esters, amides, or ammonium salts, halogen acrylic carboxylic acids or their esters, amides, or ammonium Salts, thioalcohols, thiocarboxylic acids or their esters, amides, or ammonium salts, carboxylic acid esters of thioalcohols. In, and the number of carbon atoms from 10 to 40,
The molecular weight may be 100 to 700. Particularly preferred are higher fatty acids such as lauric acid, valmitic acid, stearic acid, arachidic acid and behenic acid, which have a melting point in the range of 50 to 150 ° C., or esters, amides or ammonium salts thereof.

The mixing ratio of the resin and the organic low molecular weight substance is as follows:
5 parts by weight of organic low molecular weight substance to 100 parts by weight of resin
The range of 200 parts is preferable, and 10 to 100 parts are preferable.
Parts are more preferred.

In the present invention, the intermediate layer 16 and the protective layer 18 are made of UV-curable resin, and the UV-curable resin may be acrylic, polyester or the like.

The thickness of the intermediate layer 16 is, for example, 0.5-1.
It is about μm. The thickness of the protective layer 18 is 1 to 5 μm.
m, preferably about 1 to 3 μm.

The intermediate layer 16 is a layer for preventing the organic solvent contained in the coating material of the protective layer 18 from coloring the thermosensitive recording layer 14 when the protective layer 18 is provided. That is, when the protective layer 18 is directly provided on the thermal recording layer 14, the protective layer 1
Since the heat-sensitive recording layer 14 is colored by the organic solvent contained in 8 and recording by heat cannot be performed, the intermediate layer 16 is provided to prevent this.

It is important that the intermediate layer 16 is formed by coating, using an ultraviolet curable resin.

The solvent used for the intermediate layer 16 is required to be one that does not attack the heat-sensitive recording layer 14, and water, aromatic hydrocarbons such as toluene and xylene, methanol,
Alcohols such as ethanol and isopropanol, cycloalkanes such as cyclohexane, aliphatic hydrocarbons such as n-hexane, and other hydrocarbon-based solvents having a relatively weak polarity are used.

As a coating means, a gravure coater, a bar coater, a knife coater or the like is used.

When the intermediate layer 16 is composed of another resin, for example, a water-soluble resin, the water-soluble protective layer cannot be used, and the water-soluble resin paint contains an organic solvent contained in the protective layer. May cause swelling, which may cause the heat-sensitive recording layer 14 to develop color. In addition, since some of them show solubility in alcohol, there is a problem in terms of chemical resistance, but in the case of UV curable resin, after curing the UV curable resin, it dissolves in an organic solvent. It is advantageous in terms of chemical resistance because it does not show any properties. However, even if an ultraviolet curable resin is used as the material of the intermediate layer 16, a large number of pinholes are generated when it is formed by offset printing, and the protective layer 18 passes through the pinholes.
There is a risk that the heat-sensitive recording layer 14 may be colored by permeation of the solvent. On the other hand, according to the present embodiment, since the intermediate layer 16 is formed by coating, pinholes do not occur, and therefore there is a risk that the heat-sensitive recording layer 14 is colored or erased by the penetration of the solvent of the protective layer 18. Absent.

In particular, since the heat-sensitive recording layer composed of the leuco dye and the color developer is formed of a dispersed material, it is generally porous as compared with the reversible heat-sensitive recording layer described above, and many irregularities are formed on the surface. is there. When the intermediate layer 16 is formed by offset printing, since the viscosity of the coating material is high, the coating material does not enter the irregularities on the surface of the thermal recording layer 14, and the irregularities on the surface of the thermal recording layer 14 cannot be flattened. . On the other hand, according to this embodiment, since the intermediate layer 16 is formed by coating the ultraviolet curable resin, the intermediate layer 1
Since the viscosity of the paint of 6 may be very low, the thermal recording layer 1
(4) Since it cures in a state where it enters the unevenness of the surface, the unevenness of the surface of the heat-sensitive recording layer (14) can be flattened, and since the ultraviolet curable resin is resistant to organic solvents after hardening, it has excellent chemical resistance. A thermal recording medium can be obtained.

Therefore, according to the present heat-sensitive recording medium, since the intermediate layer 16 is formed by coating with a material containing an ultraviolet curable resin, an intermediate layer having excellent chemical resistance and no pinhole can be obtained. A material that does not cause coloration of the thermosensitive recording layer 14 when forming 18 and uses a solvent that does not adversely affect the intermediate layer 16 must be selected as a material for forming the protective layer 18 provided on the intermediate layer 16. There is no restriction that it does not occur, the selection range of the material forming the protective layer 18 is widened regardless of the type of the thermal recording layer 14, and the protective layer 18 having excellent scratch resistance and chemical resistance can be formed.

The intermediate layer 16 is not essential to the present invention and may be omitted.

For the protective layer 18, it is important to use an ultraviolet curable resin. The protective layer 18 is the thermal recording layer 1
4 It is provided to improve the scratch resistance and chemical resistance of the surface, and among the UV curable resins, the coating for the protective layer, which is particularly excellent in scratch resistance and chemical resistance, is a relatively high proportion of ketones and esters. In many cases, a solvent having a strong polarity is contained, but since the above-mentioned intermediate layer is formed according to the present embodiment, the solvent contained in the protective layer does not cause the heat-sensitive recording layer to develop or decolor. A protective layer having excellent scratch resistance and chemical resistance can be formed.

Further, it is important that the protective layer 18 is formed by coating. Conventionally, since the protective layer 18 is formed by offset printing, it is necessary to use an ink having offset printing suitability. Therefore,
For example, since there is a transfer process from the blanket, it is difficult to add a solvent, and it is difficult to adjust the viscosity, so it is not possible to add a UV-curable reactive diluent, and there are restrictions on the addition of various other additives and pigments. . On the other hand, according to the present heat-sensitive recording medium, since the intermediate layer 16 is formed by coating and the protective layer 18 is formed thereon by coating, it is not necessary to provide printability, and therefore most of solvents, reactive diluents, Various additives and pigments can be used, and coatings for all protective layers can be used. Therefore, since the chemical resistance is improved, it is possible to prevent the background fog and the disappearance of the printing due to the alcohol, the plasticizer and the like.

The protective layer 18 is formed of a material containing an ultraviolet curable resin as described above and is cured by irradiation with ultraviolet rays. However, when it is completely cured, the adhesion of the printed layer 20 at the time of forming the printed layer 20 is improved. descend. Therefore, the printing layer 2
In order to improve the adhesiveness of 0, when the protective layer 18 is formed, it is not completely cured by irradiation with ultraviolet rays, and the adhesiveness of the printing layer 20 is left by irradiating the ultraviolet rays so weakly that it does not cause blocking. After forming 22, the protective layer 18 is completely cured by irradiating it with strong ultraviolet rays again.

Here, the ultraviolet ray irradiation which does not cause blocking means C-in the infrared spectroscopic curve of the ultraviolet curable resin.
The area of the peak representing the C double bond was 10 before UV irradiation.
0% is irradiation for curing to an extent of 30 to 80%, and as a peak representing a C—C double bond in an infrared spectroscopic curve, a stretching vibration of C═C or a C—H of an alkene. The peak of bending vibration can be mentioned.

Further, when the print layer 20 and the print protection layer 22 are formed by offset printing using a UV offset ink containing an ultraviolet curable resin, the print layer 20 is used.
After printing, the print protective layer 22 is printed by weakly irradiating ultraviolet rays to the extent that blocking does not occur similarly to the above-mentioned protective layer, and then strong ultraviolet ray is again radiated to completely protect the printing layer 20 and the printing protective layer 22 together with the protective layer 18. Harden. The print layer 2
0 and the print protection layer 22 may be formed by using an ink containing an oxidative polymerization type resin. In this case, UV irradiation is performed after drying these layers.

In the above steps, the roll-shaped substrate is formed until the protective layer 18 is formed. After the protective layer 18 is formed, it is cut into a sheet shape to form the print layer 20 and the print protective layer 22.

The print layer 20 is a layer on which visible information such as desired characters and patterns is formed by printing. The print layer 20 is formed so that the visible recording information recorded on the thermal recording layer 14 can be seen.

Therefore, according to the present heat-sensitive recording medium, since the protective layer 18 is formed on the above-mentioned intermediate layer 16 by coating with the ultraviolet curable resin, it is excellent in scratch resistance and chemical resistance, and the thermal head is dirty. Does not occur,
Further, a thermal recording medium having improved adhesion of the printing layer can be obtained.

FIG. 2 shows another embodiment of the thermal recording medium according to the present invention. Substrate 1 in this example
A print layer 20 and a print protection layer 22 are sequentially stacked on one surface of the magnetic recording layer 30, and a magnetic recording layer 30 and a smoothing layer 3 are formed on the other surface.
2, the reflective layer 34, the thermosensitive recording layer 14, the protective layer 18, the print layer 20, and the print protective layer 22 are sequentially stacked.

The substrate 12, the thermosensitive recording layer 14, the protective layer 18,
The print layer 20 and the print protection layer 22 are formed similarly to the embodiment of FIG.

The magnetic recording layer 30 may be the one generally used as a magnetic recording layer in this type of magnetic recording medium.

For example, as the magnetic material, Ba-ferrite having a particle size of 10 μm or less, preferably 0.01 to 5 μm, Sr is used.
-Ferrite, Co deposited γ-Fe ₂ O ₃ , γ-Fe
₂ O ₃ , acicular iron powder, and CrO ₂ can be used, and a polyester resin, an alkyd resin, a vinyl resin, a polyurethane resin, or a mixed resin thereof which is generally used as a binder resin can be used.

The mixing ratio of the binder resin and the magnetic material is appropriately set in consideration of the adhesiveness with the substrate 12, the strength of the coating film, the voltage detected by the magnetic head, and the like. Usually, the weight ratio is in the range of former / latter = 1/1 to 1/10, preferably 1/2 to
1/8 is appropriate.

The thickness of the magnetic recording layer 30 is usually 5 to 20.
It is about μm.

The smooth layer 32 is a layer for flattening the irregularities of the magnetic recording layer 30, and is formed by gravure coating an ultraviolet curable resin. The thickness of the smoothing layer 32 is, for example, about 1 to 5 μm.

The reflective layer 34 has a color that visually hides the color of the magnetic recording layer 30 and imparts sufficient contrast to the color of the thermosensitive recording layer 14. Further, the properties that the material used to form the reflective layer 34 should have are stable under the conditions of thermal recording and have sufficient durability even if it is thin, and the thermal recording layer 14 of the material forming the magnetic recording layer 30. It is possible to prevent the transition to.

As such a heat resistant material, a thermosetting resin such as polyamide resin, epoxy resin, acrylic resin, phenol resin, unsaturated polyester resin, polyurethane resin, diallyl phthalate resin can be used. Pigment for concealing property such as Al, Sn,
Zn, Cu, Ag, Cu- Zn , etc. of the metal and Al ₂ 0 _3, T
and i0 ₂ a metal oxide such an appropriate amount.

As the reflection layer 34, a nonmagnetic metal layer such as Al, Sn, Ag or an oxide layer of these metals can be used in addition to the above-mentioned thermosetting resin.

The thickness of the reflective layer 34 is, for example, 0.03 to 0.
It is about 1 μm.

The heat-sensitive recording medium according to the present invention is not limited to the above embodiment, and the magnetic recording layer 3 is formed on both sides of the substrate 12, for example.
0, the smoothing layer 32, the reflective layer 34, the thermal recording layer 14, the protective layer 18, the printing layer 20, and the printing protective layer 22 may be provided. Further, the intermediate layer 1 is provided between the thermal recording layer 14 and the protective layer 18.
6 may be provided.

The heat-sensitive recording medium according to the present invention can be applied not only to cards but also to various recording media.

Next, specific examples of the thermal recording medium according to the present invention will be described in comparison with comparative examples in terms of composition and evaluation of physical properties.

Example 1 A magnetic recording layer having the above composition was formed on a substrate, and a smoothing layer, a reflecting layer, a heat sensitive recording layer, a protective layer, a printing layer, and a printing protective layer having the following compositions were sequentially formed. did. Smooth layer Dainippon Ink and Chemicals Inc. UV curable resin UNI
DIC C7-164 After the above materials were gravure coated, they were irradiated with ultraviolet rays by a UV lamp (160 W / cm × 3 lamps, 30 m / min) to be cured to form a smooth layer having a thickness of 3 μm. Reflective layer A reflective layer having a thickness of 0.07 μm was formed from a vapor deposited film of aluminum. Thermal recording layer Behenic acid 2 parts by weight Stearyl stearate 4 parts by weight Vinyl chloride / vinyl acetate copolymer VMCH (manufactured by Union Carbide Co.) 12 parts by weight THF 150 parts by weight Gravure-coated materials mixed in the above proportions and dried. Then, a thermal recording layer having a thickness of about 4 μm was formed. Protective layer Dainippon Ink and Chemicals, Inc. UV curable resin UNIDIC C3-374 100 parts by weight Mizusawa Chemicals Co., Ltd. Fine powder silica for thermal recording paper Mizukasil P-527 5 parts by weight Shin-Etsu Chemicals Co., Ltd. Silicon oil Shin-Etsu Silicone KF96 2 parts by weight Isopropanol 50 parts by weight The materials mixed in the above proportions are dispersed by a ball mill, and after 1 hour, gravure coating is performed and UV lamp (80 W
/ Cm × 2 lamps, 30 m / min) for ultraviolet irradiation to cure and form a protective layer having a thickness of 2 μm. At this time, the area of the peak at 1635 cm ⁻¹ representing the C—C double bond in the infrared spectroscopic curve of the ultraviolet curable resin was 1 before the ultraviolet irradiation.
It became 69% relatively as 00%. Printing layer UV offset ink FD carton manufactured by Toyo Ink Mfg. Co., Ltd. After offset printing is performed using the above ink, UV irradiation with a UV lamp (80 W / cm × 2 lamps, 30 m / min) is performed to cure, and thickness 1 to 1 A 4 μm printed layer was formed. Printing protection layer UV offset ink FDO manufactured by Toyo Ink Mfg. Co., Ltd.
P varnish After offset printing was performed using the above ink, UV rays were irradiated from a UV lamp (160 W / cm × 3 lamps, 30 m / min) to completely cure the protective layer, the printing layer and the printing protective layer. At this time, the printing protective layer had a thickness of 1 μm, and the area of the peak at 1635 cm ⁻¹ representing the C—C double bond in the infrared spectroscopic curve of the ultraviolet curable resin of the protective layer was 100 before irradiation with ultraviolet rays. 17% as a relative
Became.

Example 2 A magnetic recording layer, a smooth layer, a reflective layer and a thermosensitive recording layer were formed on a substrate in the same manner as in Example 1, and an intermediate layer and a protective layer having the following compositions were sequentially formed, and then, Example 1
Similarly to the above, a printing layer and a printing protection layer were sequentially formed, and then ultraviolet rays were irradiated again to completely cure the printing layer and the printing protection layer together with the protection layer. Intermediate layer Nippon Kayaku Co., Ltd. Protective layer ink GPS / UV200 100 parts by weight Pure water 100 parts by weight After gravure coating the materials mixed in the above proportions, UV lamps (80 W / cm × 2 lamps, 30 m / mi)
In step n), the layer was irradiated with ultraviolet rays to be cured to form an intermediate layer having a thickness of 1 μm. Protective layer UV curable resin UNIDIC V-4205 manufactured by Dainippon Ink and Chemicals, Inc. 100 parts by weight Photoreaction initiator IRGACURE 184 2 parts by weight manufactured by CIBA-GEIGY, manufactured by Mizusawa Chemical Co., Ltd. 603 10 parts by weight Silicone oil SH200 manufactured by Toray Dow Corning Silicone Co., Ltd. 2 parts by weight The materials mixed in the above proportions are dispersed in a ball mill, and after 1 hour, gravure coating is performed and a UV lamp (80W is used.
/ Cm × 2 lamps, 30 m / min) for ultraviolet irradiation to cure and form a protective layer having a thickness of 2 μm. At this time, the area of the peak at 1635 cm ⁻¹ representing the C—C double bond in the infrared spectroscopic curve of the ultraviolet curable resin was 1 before the ultraviolet irradiation.
It became 49% relatively as 00%. After forming the printing layer and the printing protection layer on this protective layer, the area of the peak at 1635 cm ⁻¹ after the ultraviolet ray was irradiated again to completely cure the protective layer was 29% relative to 100% before the ultraviolet irradiation. Became.

(Comparative Example 1) UV irradiation at the time of forming the protective layer in the above Example 1 was carried out by UV lamp (160 W / cm × 3 lamps, 30 lamps).
(m / min), the resin was completely cured by irradiation with ultraviolet rays (the area of the peak at 1635 cm ⁻¹ representing the C—C double bond in the infrared spectroscopic curve of the ultraviolet curable resin was 1 before irradiation with ultraviolet rays).
It was 24% relative to 00%. ) After that, print layer,
Each layer was formed in the same manner as in Example 1 except that the print protection layer was formed.

(Comparative Example 2) A protective layer was formed in the same manner as in Example 1 except that the protective layer of Example 1 was removed and a printing protective layer was also provided on the printed portion for thermal recording instead of the protective layer.

With respect to the above Examples and Comparative Examples, the adhesion of UV offset printing (JIS K5400, cellophane tape peeling) and the durability of print erasure were evaluated. The results are as follows. Adhesiveness of UV offset printing Durability after repeated printing and erasing Example 1 Good 256 times or more Example 2 Good 256 times or more Comparative Example 1 Peeling 256 times or more Comparative Example 2 Partial peeling 64 times or less

As described above, the adhesiveness in UV offset printing was good in Examples 1 and 2. On the other hand, in Comparative Example 1, complete peeling occurred, and in Comparative Example 2, partial peeling occurred, resulting in insufficient adhesion. Regarding the durability of print erasure, Example 1, Example 2 and Comparative Example 1 were used.
In the thermal printer, the heat plate erasing on the thermal printer could be repeated 256 times or more, but in Comparative Example 2, it was unreadable after 64 times or less.

[0066]

According to the present invention, since the printing layer is provided, visible information can be provided, and a thermosensitive recording medium having a good appearance can be obtained. The protective layer on the heat-sensitive recording layer is formed by coating a material containing an ultraviolet curable resin, and is weakly cured by ultraviolet irradiation so that it does not block. After that, a print layer and a print protection layer are formed by printing, and the protection layer is completely cured by intense ultraviolet irradiation.
Therefore, since the protective layer is not completely cured when the printed layer is formed, the adhesiveness of the printed layer on the protective layer is good. After that, the protective layer is completely cured after forming the print layer and the print protective layer, so that a thermal recording medium having excellent durability, abrasion resistance and heat resistance can be obtained. In addition, it is possible to eliminate the restriction of the paint used for the protective layer and form an effective protective layer,
It is possible to prevent the thermal head from becoming dirty and improve the chemical resistance of the protective layer.

Further, according to the present invention, the heat-sensitive layer and the protective layer are formed in a roll state, and the print layer and the print protective layer are formed by printing after being cut into a sheet shape, so that each layer can be easily formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a thermal recording medium manufactured according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the thermosensitive recording medium manufactured according to the present invention.

FIG. 3 is a diagram showing a state change of a reversible thermosensitive recording material.

[Explanation of symbols]

12 Base material 14 Thermal recording layer 16 Middle class 18 Protective layer 20 printing layers 22 Print protection layer 30 magnetic recording layer 32 smooth layer 34 Reflective layer

Claims (3)

(57) [Claims] And 1. A heat-sensitive recording layer, a protective layer of the thermosensitive recording layer, a method for producing a thermosensitive recording medium having a print layer on the protective layer, the method comprising coating a heat-sensitive recording material onto a substrate And forming a heat-sensitive recording layer, and coating the material containing the ultraviolet-curable resin on the heat-sensitive recording layer, the area of the peak representing the C-C double bond in the infrared spectral curve of the ultraviolet-curable resin A step of forming a protective layer by irradiating ultraviolet rays in an amount of 30 to 80% relative to 100% before ultraviolet ray irradiation, and a step of printing a printing layer containing an ultraviolet curable resin on the protective layer. And a step of completely curing the protective layer and the printing layer by irradiating with ultraviolet rays, the method for producing a thermal recording medium. 2. A method for producing a thermosensitive recording medium having a thermosensitive recording layer, a protective layer for the thermosensitive recording layer, a print layer on the protective layer, and a print protective layer, the method comprising: A step of coating a thermosensitive recording material to form a thermosensitive recording layer, and coating the thermosensitive recording layer with a material containing an ultraviolet curable resin, and the C--C double bond in the infrared spectral curve of the ultraviolet curable resin Forming a protective layer by irradiating the protective layer with an ultraviolet ray having an area of 30% to 80% relative to 100% before the ultraviolet ray irradiation, and an ink containing an ultraviolet curable resin on the protective layer. Printed by C, in the infrared spectral curve of the UV-curable resin
The area of the peak representing the -C double bond is 1 before the ultraviolet irradiation.
A step of forming a print layer by irradiating ultraviolet rays of about 30% to 80% as 00%, and an ink containing an ultraviolet curable resin is printed on the print layer to form a print protection layer. A method for producing a heat-sensitive recording medium, comprising: a step; and a step of completely curing the protective layer, the print layer, and the print protective layer by irradiating ultraviolet rays. 3. The method according to claim 1, wherein the step of forming the protective layer is performed on the base material in a roll state, and the step of forming the print layer is a base material in a sheet state. A method for manufacturing a thermal recording medium, characterized in that