JP2787847B2 - Repetitive thermal recording method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repetitive thermal recording method, and more particularly, to a repetitive thermal recording method capable of repeatedly writing and erasing visible information.

(Prior art) Conventionally, telephone cards, ticket purchase cards, highway cards, cash cards, ID cards, IC cards,
Various cards such as a membership card are widely used.

Many of these cards record various types of information, and some of the information is sometimes visible. However, most of the information is recorded on a magnetic recording layer or an IC provided on the card.

In the various cards described above, it may be desirable to make part of a change in information recorded in the magnetic recording layer and information newly recorded each time the card is used visible.

For example, in the case of a telephone card as an example, it is desirable that the user know the use frequency (that is, the remaining frequency) with the naked eye each time the user uses the card. In the case of a ticket purchase card, it is desirable to know the balance remaining on the card each time it is used, and in the case of a highway card, it is desirable that the date of use and the like be recorded visually. Conventionally, a punch hole is provided in the card for such a demand, so that an approximate guide can be understood. Further, a method of recording visual information on a base material by a thermal recording means such as a thermal head is employed. As another method, recording using a photochromic material or a thermochromic material which causes a color change by light or heat has been proposed.

(Problems to be Solved by the Invention) When the visual information as described above is represented by punching, it is impossible to display detailed information, and it is merely a rough guide. On the other hand, in the irreversible recording method using a thermal head or the like, the display information is naturally limited because the surface area of the card itself is small.

As a method for solving such a drawback, a method of using a photochromic material or a thermochromic material which can be repeatedly written and erased for a recording layer has been proposed. However, this method has a memory property, light resistance and heat resistance. Poor performance and poor durability, far from practical use.

As a means for solving the above-mentioned drawbacks, the present inventor has proposed a method in which a transparent state and a white turbid state are reversibly changed as a phase change by heat on a card, and a reversible polymer composed of a polymer composition capable of maintaining the above two forms at room temperature We proposed a card that can be repeatedly printed with a thermal recording layer, but in this case, the thermal recording layer is made of a thermoplastic resin as a matrix. As a result, recording marks remain, the surface of the thermal recording layer is roughened, the surface smoothness is lost, and the resolution and quality of printed characters are reduced due to unevenness and irregular reflection on the printed surface.

It is also possible to provide a protective layer on the thermal recording layer in order to solve such drawbacks, but in this case, the problem is simply shifted to the protective layer, and although a slight improvement is obtained, Experiments have shown that this is not a solution.

The above-described problem occurs not only in the card but also in the same type of recording medium.

Accordingly, an object of the present invention is to provide a novel thermal recording method capable of repeatedly printing a large amount of visual information without roughening the surface of the thermal recording layer.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention, at least a part of the substrate surface,
A recording medium having a reversible thermal recording layer made of a polymer composition capable of maintaining the above-mentioned two forms at room temperature, wherein the transparent state and the cloudy state are reversibly changed as a phase change by heat, and repeated by a contact heating element. In the thermal recording method for recording,
A repetitive thermal recording method characterized by running a tape-like film between a heating element and a recording medium for printing each time recording is performed.

(Function) When recording is repeatedly performed on a recording medium having a reversible thermal recording layer by a contact-type heating element, printing is performed by running a tape-like film between the heating element and the recording medium each time recording is performed. This prevents the surface of the thermal recording layer from being roughened, improves the durability of the recording layer, and enables high-resolution and high-quality printing even when printing and erasing are repeated many times.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments.

The substrate of the recording medium used in the present invention may be a sheet-like or film-like substrate such as paper, plastic film, and metal, and any of the conventionally known recording medium substrates may be used in the present invention. Can be done.

For example, when the present invention is used for a card, a conventionally known card itself may be used, for example, a telephone card,
The structure of various cards or card bases such as a ticket purchase card, a highway card, a cash card, an ID card, an IC card, a membership card and the like can be used as they are.

The thermal recording layer used in the present invention is described in, for example,
JP-A-54-119377, JP-A-55-154198, JP-A-61-258853
JP-A-58-7683, JP-A-57-109695 and JP-A-57
-82086 to 82088, etc. These materials are polymer compositions which can be reversibly changed between a transparent state and a cloudy state by heat and can maintain the above two forms at room temperature. For example, these materials cloudy upon cooling after heating to a temperature above T ₁ than room becomes transparent when and cooling after heating to a temperature T ₂ lower than the higher and T ₁ than room.

Accordingly, a thermal recording layer is formed on a substrate from these polymer compositions, and this layer is heated to a temperature T ₂ lower than T ₁ and higher than room temperature.
Overall the cooling is later heated to become a clear film, a white character is formed by opaque and is printed by T ₁ or more temperature by the thermal head or the like to the transparent film. Heating characters to a temperature again T ₂ on the entire surface after forming these characters are erased, thereby enabling printing again above T ₁ of the temperature. Further, the entire reverse is clouded by T ₁ or more temperatures, it can also be printed out for extracting character shape at a temperature of T _2.

Any of the polymer compositions having the physical properties as described above can be used in the present invention. Preferred specific examples include, for example, polyvinyl chloride, a vinyl chloride-based copolymer,
A vinylidene chloride copolymer, a thermoplastic resin such as polyester is used as a matrix material, and a saturated or unsaturated fatty acid having 10 to 30 carbon atoms, an organic low-molecular substance such as an ester, an amide or an ammonium salt thereof is contained in the matrix material. It is dispersed. The weight ratio of the matrix material to the organic molecular substance is in the range of 3: 1 to 16: 1, preferably 6: 1 to 12: 1 by weight.

The recording medium used in the present invention is provided with a thermal recording layer composed of the above-mentioned polymer composition on at least a part of the surface of the base material. Specific examples of the case where the present invention is applied to a card include, for example, , FIG. 1 and FIG.

The example shown in FIG. 1 is an example applied to a prepaid card such as a telephone card. In this example, a heat recording layer 2 is formed on the surface of a polyester card substrate 1 (100 to 300 μm thick).
(Thickness: 2 to 40 μm). In a preferred example, a colored layer 3 is provided between the thermal recording layer 2 and the card substrate 1 in order to increase the contrast of a visible image generated by printing.
(It may be of any thickness).

For example, when the colored layer 3 is made black, white characters are printed on a black background in the case of cloudy printing, while black characters are printed on a white background in the case of transparent printing. In the case of coloring in the hue, the character and the background have the corresponding hue. Conversely, the surface of the card base may be colored white, and the thermal recording layer itself may be colored. Of course, if the card substrate itself is colored, the color of the thermal recording layer is preferably a different hue.

Further, in order to improve the durability of the thermal recording layer 2, a protective layer 4 (1 to 8 μm in thickness) made of a transparent polyester resin or acrylic resin can be provided on the surface thereof. It can be formed from a crosslinkable resin such as a resin or a photocurable resin. Also, the thermal recording layer 2
May be provided between the thermal recording layer 2 and the underlayer to improve the adhesiveness (the thickness may be arbitrary).

In a preferred embodiment of the present invention, when the card base 1 having the magnetic recording layer 6 is used, the magnetic recording layer 6 itself is colored.
And the coloring layer 3. Since such a magnetic recording layer 6 is excellent in thermal conductivity, the diffusion of heat applied during printing is good and the printing portion is rapidly cooled. As a result, printing becomes sharp and printing with excellent resolution is obtained. Of course, the colored layer 3 may be formed on the magnetic recording layer 6.

As described above, the heat-sensitive recording layer, the colored layer, the protective layer, the adhesive layer, and the magnetic recording layer formed on the card substrate are all on both sides of the card substrate, all on one side, one part, or the area as embedded. The installation place is not particularly limited, and may be provided in accordance with the purpose of use of each card.

Specific examples shown in FIG. 2 are cash cards, ID cards,
This is an example of a card such as a membership card in which the card base is made of hard vinyl chloride resin. In this example, the center core layer 7 (280 to 660 μm in thickness) and the oversheets 8 (50 to 100 μm in thickness) on both sides thereof Although an example is shown in which the thermal recording layer is embedded in one of the oversheets 8 of the card base material 10, the thermal recording layer may be provided on the surface without being embedded. The configuration of the thermal recording layer 2, the coloring layer 3, the protective layer 4, the adhesive layer 5, the magnetic recording layer 6, the combination thereof, the installation area, the installation location, and the like can be various modes as in the example shown in FIG. is there. The substrate may be thick or thin.

The card which can be repeatedly printed as described above can be obtained by preparing an appropriate card or card base material and forming the respective layers on the surface thereof by a conventional means such as a printing method and a transfer method.

In addition to the thermal recording layer, it is a matter of course that various known prints, decorations, embossed characters and the like may be formed on the card.

The above is an example of a recording medium using the present invention, and the present invention is not limited to these cards, and as long as the above-mentioned thermal recording layer is provided on a base material, for example, other heads such as an overhead projector and an electronic blackboard The recording medium may be used.

The heating element used in the present invention is generally a thermal head, and other heating pens can also be used, and any recording means having these heating elements can be used in the present invention.

The film used in the present invention may be any thin film that does not break due to contact with the thermal head and that transmits the heat of the thermal head to the thermal recording layer satisfactorily. The film itself necessarily has high heat resistance. No need.

For example, preferred resin films include films made of known resins such as polyethylene, polypropylene, polyester, polyamide, polycarbonate, polyurethane, aramid, polysulfone, cellophane, and acetylcellulose. As another example, inorganic films such as aluminum foil, glass and mica can be used. In particular, when a thermoplastic resin film is used, one or both sides thereof are subjected to a release treatment with a release agent such as silicone or a fluorine resin so that one or both sides thereof do not adhere to the thermal head or the thermal recording layer during printing. Is preferred.

Since the film as described above needs to sufficiently transmit the heat of the thermal head to the thermal recording layer, it should not be too thick. For example, a film having a thickness of about 1 to 20 μm is preferable.

The method of the present invention is a method using a recording medium, a heating element and a film as described above.
Any method may be used as long as printing is performed by running a tape-like film between the heating element and the recording medium, and there is no particular limitation.

FIG. 1 is a view schematically showing a preferred method of the present invention. As shown in the figure, a film 12 is wound into a tape and wound into a roll, and the film 12 is moved between a thermal head 11 and a thermal recording layer 2. This shows a method of printing by a conventional method.

In the above method, if the overall heat recording layer 2 is transparent, white characters are formed by opaque and is printed by T ₁ or more temperature by the thermal head 11. These characters when heating the entire surface to a temperature T ₂ are when the character is no longer needed is erased, it is possible to cloudy printing again above T ₁ of the temperature. Further, if the entire heat recording layer is cloudy it can also be printed out for extracting character shape at a temperature of T _2.

When printing and erasing as described above are repeated, the film 12 is interposed between the thermal head 11 and the thermal recording layer 2 according to the method of the present invention, so that the impact force of the thermal head 11 is absorbed by the film and only the heat is applied. Is transmitted to the thermal recording layer 2, so that the surface of the thermal recording layer 2 is sufficiently protected. In particular, by running the film 12 for each print, the film 12
Is not heated and pressurized many times by the thermal head 11 at the same location, so that the film 12 can be an ordinary thermoplastic film.On the contrary, since the film 12 is a thermoplastic film, the impact force of the thermal head 11 can be sufficiently increased. And only heat is transmitted to the thermal recording layer 2, and the thermal recording layer 2 is further protected.

(Effects) According to the present invention as described above, when recording is repeatedly performed on a recording medium having a reversible thermal recording layer by a contact-type heating element, a tape-shaped member is formed between the heating element and the recording medium each time recording is performed. By running the film, the surface of the thermal recording layer is prevented from being roughened, the durability of the recording layer is improved, and high-resolution and high-quality printing can be performed even when printing and erasing are repeated many times.

Further, in a preferred embodiment, the film may be a tape, and run on the thermal recording layer, so that the film may be a general thermoplastic resin film, and the film itself is deformed by heat and pressure, and particularly the pressure is reduced. The thermal recording layer is sufficiently protected by absorption.

In another preferred embodiment, a printed layer can be made clear and easy to see by providing a colored layer on the lower surface of the thermal recording layer.

(Example) Next, the present invention will be described more specifically with reference to examples.
In the following description, “part” or “%” is based on weight unless otherwise specified.

Example 1 On the other side of a 200 μm-thick white polyester film having a magnetic recording layer formed on one side, characters, pictures, and the like were printed by an offset printing method.

On the other hand, 10 parts of a 5% solution of behenic acid in tetrahydrofuran was added to 60 parts of a 30% solution of a vinylidene chloride-acrylonitrile copolymer in tetrahydrofuran to obtain a mixture. This mixture was applied on the above-mentioned magnetic material layer with a wire bar and dried to form a 10 μm-thick opaque white heat-recording layer to obtain a repeatable printable card.

Next, the card was heated to an atmosphere of 65 ° C. and then cooled to make the thermal recording layer transparent, whereby the lower magnetic recording layer appeared black.

This transparent thermal recording layer has a thermal head (resistance 320Ω)
When printing was performed directly under the conditions of applied voltage 10 V and applied time 3 msec, the printed part changed to opaque white,
The printed characters were clearly readable. When the printed card was passed between two heating rolls having a surface temperature of 65 ° C. and allowed to cool, the whole surface became transparent and the white characters disappeared, and the black color of the lower magnetic recording layer was seen, that is, the erased state. It became.
When the surface of the recording layer was examined after repeating the above-mentioned writing and erasing five times, the surface was rough, and when the printed characters were examined with a microscope, the periphery became jagged,
Also, the periphery appeared to be blurred due to irregular reflection on the surface.

Next, when performing printing with the thermal head in the above method, using a cassette containing a polyester tape having a width of 8 mm and a thickness of 12 μm, the tape is run between the thermal head and the thermal recording layer for each printing, and From as well as 20
When printing was repeated 0 times and the state of the surface of the thermal recording layer was examined in the same manner as described above, no roughness of the thermal recording surface was observed, and the printed characters were sharp and had high resolution.

Example 2 A urethane acrylate-based ultraviolet curable resin was applied to the surface of the thermal recording layer in Example 1 and cured by irradiation with ultraviolet light to form a transparent protective layer having a thickness of 5 μm. When printing was performed in the same manner as in Example 1 using this card, when the film was not interposed, considerable roughness was observed in the thermal recording layer by printing 10 times. However, a polyimide film having a thickness of 6 μm was interposed. in case of
Even at 200 times, no roughness was recognized at all, and printing with higher resolution was possible.

Example 3 White rigid polyvinyl resin sheet of the center core chloride having a thickness of 500μm and the over sheet of the top and bottom of a thickness 100μm transparent hard vinyl chloride resin placed on top one by one, 0.99 ° C. using a pressing machine, 120 kg / cm ² Under the conditions described above, heating and pressing were performed for 30 minutes to form a concave portion for embedding the recording material.

Next, the recording material obtained by providing the thermal recording layer on the magnetic recording layer obtained in Example 1 is inserted into the concave portion of the vinyl chloride resin sheet, and a card that can be repeatedly printed is printed in the same manner as in Example 1. When performed, similar effects were obtained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a method when a recording medium used in the present invention is a card, and FIG. 2 is a diagram schematically illustrating another configuration of a card.

Claims (6)

(57) [Claims] 1. A reversible thermal recording comprising a polymer composition on at least a part of the surface of a base material, which changes reversibly between a transparent state and a cloudy state by heat as a phase change and can maintain the above two forms at room temperature. In a thermal recording method of repeating recording on a recording medium having a layer by a contact-type heating element, printing is performed by running a tape-like film between the heating element and the recording medium each time recording is performed. Iterative thermal recording method. 2. The method according to claim 1, wherein the film is a resin film or an inorganic film. 3. The repetitive thermal recording method according to claim 1, wherein a coloring layer is provided between the substrate and the thermal recording layer. 4. The method according to claim 3, wherein the colored layer is a magnetic recording layer. 5. A film according to claim 1, wherein the film is subjected to a release treatment.
4. The repetitive thermal recording method according to any one of 4. 6. The repetitive thermal recording method according to claim 1, wherein a protective layer is provided on the thermal recording layer.