JP3118322B2 - Visible recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a commuter pass, an admission permit,
The present invention relates to a recording medium that is used repeatedly such as various prepaid cards and has a recording layer capable of repeatedly forming and erasing a visible image.

[0002]

2. Description of the Related Art A commuter pass for transportation, a permit to enter an event site or a building, and the like are repeatedly used every day, but there is no means for checking illegal riding and unauthorized entry in management. Magnetic cards and the like are also used in various prepaid cards. However, since the recorded contents cannot be directly viewed, the amount of payment and the balance cannot be easily checked, and there is a problem in guaranteeing the contents to the user.

[0003] For this reason, conventionally, a method has been proposed in which a visible record is recorded on a card each time it is used, and the record is erased. For example, it has been proposed to disperse an organic low-molecular substance in a synthetic resin base material and use a material that changes between a transparent state and an opaque (white turbid) state depending on temperature (Japanese Patent Laid-Open No. 55-154198). This material becomes transparent when cooled to a normal temperature from a specific temperature range T ₁ , and becomes a temperature range T higher than T _1.
Because it has the property of becoming cloudy when cooled from ₂ to room temperature,
Utilizing this, the visible image can be reversibly printed / erased.

As means for printing / erasing, there are a thermal head, a heating stamp, a heating roller and the like. However, in order to perform rewriting repeatedly, it is necessary to provide a protective layer on the surface of the recording layer. As the protective layer, a laminated layer of a heat-resistant film such as a polyethylene terephthalate film or a layer coated with an ultraviolet curable resin has been proposed.

[0005]

However, a laminate of a thin heat-resistant film such as a polyethylene terephthalate film is slightly insufficient in heat resistance when repeatedly rewritten with a thermal head or the like, resulting in print marks and scratches. There is a problem that the range of good printing conditions is narrow.

In the case of applying an ultraviolet curable resin, the heat resistance of the resin itself is excellent, but it has been found that there are the following problems.

(1) When coating or printing an ultraviolet-curable resin on the recording layer, the organic low-molecular substance in the recording layer blows out to the surface, so that the adhesiveness is deteriorated and the change with time tends to occur. (2) Even if the recording layer is coated with an ultraviolet curable resin, a low-molecular organic substance may be blown on the resin. (3) When coating an ultraviolet-curable resin, the effect of the solvent used on the recording layer becomes a problem, and the solvent sometimes sucks out blowing of low-molecular substances. (4) The UV-curable resin coating film is generally hard and has a large heat shrinkage. Therefore, if the rewriting is performed repeatedly, it does not follow the movement of the underlying recording layer due to heat, and the protective layer is likely to be cracked or distorted.

[0008]

SUMMARY OF THE INVENTION The present invention solves these problems and provides a protective layer having excellent performance. The gist of the present invention is that at least a part of the surface of a substrate is transparent by temperature. In a visible recording medium having a visible recording layer made of a synthetic resin material that causes a reversible change between a state and an opaque state, and having a protective layer on the upper surface of the recording layer, the protective layer is formed on the heat-resistant synthetic resin film and the film. A visible recording medium characterized by comprising a formed ultraviolet or electron beam curable resin coating film.

According to the present invention, the contact surface with a thermal head or the like is made of an ultraviolet or electron beam curable resin coating,
Since the heat resistance and hardness, which are the advantages, are sufficiently exhibited, and a heat resistant synthetic resin film is interposed between the recording layer and the recording layer,
The blowing of the low molecular substance from the recording layer is suppressed, the influence of the solvent, the difference in the heat shrinkage between the layers, and the like are alleviated, so that good repetition durability can be provided.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an example of a recording medium (card) obtained by the method of the present invention.

The card obtained by the present invention has a visible recording layer 2 provided on one surface of a substrate 1 such as a polyethylene terephthalate (PET) sheet having a high strength, and a protective layer 3 formed thereon. It is preferable to provide a metallic reflective layer 4 between the base material 1 and the recording layer 2 in order to enhance the visibility of recording, and usually has a magnetic recording layer at an appropriate position.

The protective layer 3 is made of a heat-resistant synthetic resin film 31.
And an ultraviolet or electron beam curable resin coating film 32.

The heat-resistant synthetic resin film 31 is preferably transparent, high in heat resistance and thin.
Films such as polyester such as polyethylene naphthalate, polysulfone, polyphenylene sulfide, polyetherimide, polyetheretherketone, and polyethersulfone can be used. These films are formed in advance and are laminated on the recording layer 2 by a so-called laminating method.

Examples of the UV-curable resin include general monomers or oligomers such as urethane acrylates, ester acrylates, epoxy acrylates and butadiene acrylates, and various functional monomers, surfactants and defoamers. An additive such as an agent is added as required, and a photopolymerization initiator is further added. In addition, the same type of resin can be used as the electron beam curable resin.

The UV-curable resin film 32 can be formed on the heat-resistant synthetic resin film 31 by applying a UV-curable resin using a roll coater, a gravure coater, or the like, or by offset printing. .

The protective layer 3 may be formed by laminating a heat-resistant film 31 on the recording layer 2 of the recording medium and then forming an ultraviolet-curable resin coating film 32 thereon, or by forming a film on the heat-resistant film 31. UV curable resin coating 32
Can be separately formed and then laminated on the recording layer 2.

The total thickness of the protective layer 3 is preferably about 1 to 15 μm. If the thickness is smaller than this, the production becomes difficult. If the thickness is too large, the heat conduction is deteriorated. This is not preferable in terms of durability and equipment.

The recording layer 2 shows a visible reversible change between a transparent state and an opaque state, and is made of a synthetic resin material capable of maintaining these two levels at room temperature. For example, this material is disclosed in JP-A-55-154198 and JP-A-58-4599.
8, transparent synthetic resins such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinylidene chloride, vinylidene chloride copolymer, polyester, polyamide, polystyrene, and polymethyl (meth) acrylate It is composed of a composition in which higher fatty acids, aliphatic saturated dicarboxylic acids, higher fatty acid esters, higher ketones, higher alcohols and the like are dispersed as low molecular substances.

The metallic reflective layer 4 can be formed of a vapor deposited layer of aluminum, tin, silver, or the like, or a foil, or a paint layer mixed with aluminum powder or the like, and has an effect of improving the visibility of recording. . Similarly, in order to enhance the visibility of the recording, the heat-resistant film 31 and / or the ultraviolet-curable resin coating film 32 can be colored transparently.

The recording medium material of the present invention comprises a thermal head,
Temperature T by a heating means such as a heating stamp or a heating roll.
_When heated at ₁ (for example, 70 to 100 ° C.), it becomes transparent.
The then this transparent recording materials, thermal head, do it like a heating stamp locally heated to a higher temperature T ₂ than T _1, only the heated portion is opacified (cloudy),
A visible image can be displayed. To erase the image, it may be heated to a temperature range T ₁ again.

The recording medium thus obtained can be used, for example, as a prepaid card for admission, shopping, rental, etc., and each time it is used, the used amount and the remaining amount are displayed on the visible recording layer 6 together with the magnetic recording. By doing so, it is always possible to know the exact balance. It can also be used as a rewritable thermosensitive recording paper.

[0022]

【Example】

(Example) A reflective layer was formed by vapor-depositing aluminum on the surface of a transparent PET sheet having a thickness of 188 μm, and a recording material comprising the following composition was dissolved in tetrahydrofuran, applied, dried, and dried to form a 10 μm-thick. A visible recording layer was formed.

100 parts by weight of vinyl chloride-vinyl acetate copolymer (MRP-TS manufactured by Nissin Chemical Co.) 40 parts by weight of 12-tricosanone 10 parts by weight of 1,12-tetradecanedioic acid

Then, a PET film having a thickness of 2 μm is stuck on the visible recording layer as a heat-resistant film, and a UV-curable resin comprising the following composition is dissolved in isopropyl alcohol and applied by a gravure coater. ,
Ultraviolet rays were irradiated under the conditions of 80 W / cm and 10 m / min to form a coating film having a thickness of 2 μm.

Urethane acrylate oligomer 65 parts by weight Reactive diluent (modified diacrylate) 25 parts by weight Photopolymerization initiator 6 parts by weight Other additives 4 parts by weight

Then, a card was punched out into a card shape to prepare a card. The card thus obtained was cloudy in the initial state, but when the surface was heated with a heating stamp at 80 ° C., the portion became transparent. Next, when characters were printed with an energy of 0.28 mJ / dot using a thermal head of 8 dots / mm, the printed portion of the recording layer became cloudy, and clear characters appeared.

Further, the surface of the UV-curable resin coating film has
No deterioration phenomenon such as scratches or cracks was observed, and no deterioration was observed even after printing / erasing was repeated 500 times.

For comparison, a heat-resistant film P
When an ultraviolet curable resin was directly applied on the recording layer without using an ET film, print marks (irregularities) and cracks of the thermal head were generated. It is presumed that this is because in the present invention, since the base of the ultraviolet-curable resin coating film is a firm heat-resistant film, deformation and thermal expansion and contraction of the coating film due to external force are suppressed.

[0029]

According to the present invention, by forming a laminate layer of a heat-resistant film and an ultraviolet or electron beam curable resin coating film as a protective layer on the recording layer, the organic low molecular substance in the recording layer can be reduced. Spouting can be suppressed to prevent deterioration of coating film adhesion and spouting to the surface of the protective layer, and it is possible to eliminate the influence of the solvent used on the recording layer when coating the ultraviolet curable resin.

The UV-curable resin coating film has excellent durability without scratches, cracks, distortions, etc.
Also, manufacturing can be greatly facilitated.

[Brief description of the drawings]

FIG. 1 is a sectional view of a card showing an example of a recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Visible recording layer 3 Protective layer 31 Heat resistant synthetic resin film 32 UV curable resin coating film 4 Metallic reflective layer

Claims (1)

(57) [Claims] At least a portion of a surface of a base material has a visible recording layer made of a synthetic resin material that reversibly changes between a transparent state and an opaque state depending on temperature, and a visible layer having a protective layer on the upper surface of the recording layer. A visible recording medium comprising a recording medium, wherein the protective layer comprises a heat-resistant synthetic resin film and an ultraviolet or electron beam curable resin coating film formed on the film.