JPH06122273A - Reversible thermal recording sheet - Google Patents

Abstract

PURPOSE:To provide a reversible thermal recording sheet, in which UV shielding capacity is improved and head matching properties and heat distortion resistance are enhanced. CONSTITUTION:In a reversible thermal recording sheet, in which a reversible thermal recording layer capable of repeating recording and erasing is formed onto a support and a protective layer using a heat distortion-resistant resin as a binder is shaped onto the recording layer, the reversible thermal recording sheet, in which a UV absorber is contained in at least either one layer of the reversible thermal recording layer or the protective layer, can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive recording sheet, and more particularly to a reversible thermosensitive recording sheet which forms and erases an image by the difference in thermal energy.

[0002]

2. Description of the Related Art Sheets having a thermosensitive coloring layer containing a coloring composition as a main component on a support such as paper, synthetic paper, plastic film, etc. have hitherto been used in electronic calculators, facsimiles,
It is widely used for labels, word processors, thermal printers, plotters, etc., and is highly evaluated for its stable recording characteristics, high image quality, and easy device handling.
The field of use is also wide.

By the way, in recent years, a reversible thermosensitive recording material capable of reversibly generating / deleting an image has been strongly demanded due to the cost side due to the increase in the amount of information, the problem of paper disposal or the problem of resource protection. The materials are also disclosed in, for example, JP-A-58-191190, JP-A-60-193691, and US Pat. No. 3,666,525. The thermochromic composition used for such a reversible thermosensitive recording sheet is generally composed of a color former and a color-developing substance (color-developing agent) that causes the color-developing agent to develop / decolor by the difference in thermal energy. As the color former, for example, a colorless or light-colored leuco dye having a lactone ring or the like is used, and as the color-developing agent, for example, at least one of a phenolic hydroxyl group and a carboxyl group, and an amino group having a functional group or Amphoteric compounds that are part of the salt compound are used.

[0004]

However, in this type of recording material, the light resistance of the image part and the background part is smaller than that of a general thermal recording paper (when exposed to a fluorescent lamp or sunlight for a long period of time). (The density of the image area is reduced and the discoloration of the background area is remarkable.)
The image was not clear enough to satisfy practical use.

That is, in these reversible thermosensitive recording sheets, the shielding of ultraviolet rays is about 10% at a wavelength of 385 nm and 400 nm.
I couldn't shield it at all. Since these sheets are repeatedly used, they are more often exposed to sunlight than general thermal recording paper, and as a result, the density of the image area is reduced and the discoloration of the background is noticeable due to sunlight, etc. It did not have satisfactory light resistance.

Further, when polyvinyl alcohol, polyester resin or the like which is usually used as a binder for the protective layer is used, problems such as poor head matching such as sticking and adhesion of dust and deformation of the binder due to thermal printing are caused. Occurs.

An object of the present invention is to solve the problems of the above-mentioned prior art and to provide a reversible thermosensitive recording sheet having improved ultraviolet shielding ability, improved head matching property and thermal deformation resistance. It is in.

[0008]

The above object is to provide a reversible thermosensitive recording layer capable of repeatedly recording and erasing on a support, and to provide a protective layer using a heat-deformable resin as a binder on the recording layer. In the reversible thermosensitive recording sheet provided, a reversible thermosensitive recording sheet characterized by containing an ultraviolet absorber in at least one layer of the reversible thermosensitive recording layer or the protective layer. Can be achieved.

[0009]

The above is the conclusion obtained as a result of the intensive study by the present inventors in order to achieve the above-mentioned object. As the ultraviolet absorbing substance, an ultraviolet absorbing benzotriazole compound is used.
The protective layer contains a mixture with a UV-absorbing benzophenone compound capable of shielding a wavelength of 430 nm or less in a protective layer binder, or an ultraviolet-absorbing benzotriazole compound alone capable of shielding a wavelength of 430 nm or less as a protective layer It has been found that the problem can be solved by incorporating it in a binder and using a heat-resistant deformation resin whose Tg is outside the thermal recording temperature range as the binder.

By including in the binder an ultraviolet absorbing compound capable of shielding a wavelength of 430 nm or less, visible light is hardly affected, and light of a wavelength of 400 nm or more, which could not be shielded so far, is also shielded. The light resistance can be improved. Further, by using a heat-resistant deformation resin whose Tg is outside the thermal recording temperature range as the binder, it is possible to improve the head matching property and improve the deformation of the binder due to thermal printing.

[0011]

EXAMPLES The reversible thermosensitive recording sheet of the present invention will be specifically described below with reference to examples.

[0012]

Example 1 First, a void-containing polyester film G1215 (with an antistatic layer manufactured by Toyobo Co., Ltd.) was used as a support, and a reversible thermosensitive recording material having the following composition was coated on the surface thereof with a wire bar coater. It was dried at ℃ for 30 minutes.

Color-developing dye (TH-105 manufactured by Hodogaya Chemical Co., Ltd.) ... 1.0 parts by weight Developer and developer (gallate / octadecylamine complex) ... 5.8 parts by weight Acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd.) 20% toluene solution ... 10.0 parts by weight Stearic acid amide… 1.0 parts by weight Solvent (toluene)… 29.0 parts by weight Next, the surface of the sample obtained above is coated with a coating solution for the protective layer having the following composition to a thickness of about 1 μm. It was applied with a coater to form a protective layer.

Benzophenone-based compound (CYASORB UV-24, manufactured by AMERICAN CYANAMID Co.) 0.7 parts by weight Benzotriazole-based compound (SEESORB 709, manufactured by Cypro Kasei Co., Ltd.) 0.5 part by weight Heat-resistant methacrylic resin (Dianal BR- 179, Mitsubishi Rayon Co., Ltd.) 10% toluene solution… 90 parts by weight Calcium carbonate (Shiraishi Industry Co., Ltd. Brilliant-15)… 5.0 parts by weight Zinc stearate… 1.0 parts by weight Toluene… 35 parts by weight

[0015]

Example 2 A reversible thermosensitive recording material was coated on a support and dried in the same manner as in Example 1, and a protective layer coating solution having the following composition was formed on the surface of the sample to a thickness of about 1 μm. Coating was performed using a wire bar coater to form a protective layer.

Benzotriazole-based compound (SEESORB 706, manufactured by Cipro Kasei Co., Ltd.): 1.0 part by weight Heat-resistant methacrylic resin (Dianal BR-179, manufactured by Mitsubishi Rayon Co., Ltd.) 10% toluene solution: 90 parts by weight Calcium carbonate (Shiroishi Industry Co., Ltd. Brilliant-15): 5.0 parts by weight Zinc stearate: 1.0 parts by weight Toluene: 30 parts by weight

[0017]

[Comparative Example 1] A reversible thermosensitive recording material was coated on a support and dried in the same manner as in Example 1, and a protective layer coating solution having the following composition was formed on the surface of the sample to a thickness of about 1 μm. Coating was performed using a wire bar coater to form a protective layer.

Benzotriazole-based compound (SEESORB 701, manufactured by Cypro Kasei Co., Ltd.)… 1.0 part by weight Heat-resistant methacrylic resin (Dianal BR-179, manufactured by Mitsubishi Rayon Co., Ltd.) 10% toluene solution… 90 parts by weight Calcium carbonate (Brilliant-15 manufactured by Shiraishi Industry Co., Ltd.)… 5.0 parts by weight Zinc stearate… 1.0 parts by weight Toluene… 30 parts by weight

[0019]

[Comparative Example 2] As in Example 1, a reversible thermosensitive recording material was coated on a support and dried, and a protective layer coating solution having the following composition was formed on the surface of the sample to a thickness of about 1 μm. Was applied using a wire bar coater to form a protective layer.

Benzophenone-based compound (SEESORB 103, manufactured by Cipro Kasei Co., Ltd.)… 1.0 parts by weight Acrylic resin (Acrypet-MF, manufactured by Mitsubishi Rayon Co., Ltd.) 20% toluene solution… 45 parts by weight Calcium carbonate (Shiroishi Industry ( Ltd., Brilliant-15) 5.0 parts by weight Zinc stearate 1.0 parts by weight Toluene 35 parts by weight The samples obtained in the above Examples and Comparative Examples were subjected to the various tests described below, and the results shown in Table 1 were obtained. Obtained.

Light resistance test: General thermal printer AP-8
The image part and the background part colored with 50 (manufactured by Seiko Epson Corporation) were exposed to sunlight for 20 hours, and the change in the density of the image part and the change in the background part were measured with a Macbeth densitometer.

Decoloring test: After exposing the image part and the background part colored by the same thermal printer to the sunlight for 20 hours, the image was recorded by using an infrared heating type heat roll at 110 ° C. It was confirmed whether the parts would be erased.

Head matching property: Using the same thermal printer as described above, continuous printing was performed for a length of 1 m, and sticking and head residue adhesion at that time were evaluated.
In the display of the results in the table, ○, Δ, and × indicate that the head matching is good, medium, and bad, respectively.

Thermal deformation resistance test: Printing by the same thermal printer as above and erasing by an infrared heating type heat roll at 110 ° C. were repeated 15 times, and the sample surface was evaluated. In the display of the results in the table, ○, △, × are "no change" respectively,
It indicates that "light print marks were attached" and "the protective layer was broken".

[0025]

[Table 1]

From these results, the first and second embodiments are
It can be seen that the light resistance is excellent as compared with Comparative Examples 1 and 2, and the decoloring property, the head matching property, and the heat distortion resistance are excellent as compared with Comparative Example 2.

[0027]

As described above, the reversible thermosensitive recording sheet has the constitution of the present invention, that is, the reversible thermosensitive recording layer capable of repeating recording and erasing is provided on the support, In a reversible thermosensitive recording sheet provided with a protective layer using a heat-resistant deformation resin as a binder on the recording layer, an ultraviolet absorber is contained in at least one layer of the reversible thermosensitive recording layer and the protective layer. By using a reversible thermosensitive recording sheet characterized by that, the reversible sensation that solves the problems of the prior art, improves the ultraviolet shielding ability, and improves head matching and heat distortion resistance. A thermal recording sheet could be provided.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Uchiyama 3819 Noborito, Tama-ku, Kawasaki City, Kanagawa Prefecture Sliontech Co., Ltd.

Claims (4)

[Claims] 1. A reversible thermosensitive recording sheet comprising a support and a reversible thermosensitive recording layer on which recording and erasing can be repeated, and a protective layer using a heat-deformable resin as a binder on the recording layer. In the above reversible thermosensitive recording layer, a reversible thermosensitive recording sheet containing an ultraviolet absorber in at least one of the reversible thermosensitive recording layer and the protective layer. 2. The reversible thermosensitive material according to claim 1, wherein the ultraviolet absorber is a single substance or a mixture of two or more kinds of substances and is an ultraviolet absorber capable of blocking a wavelength of 430 nm or less. Recording sheet. 3. The reversible thermosensitive recording sheet according to claim 1, wherein the binder of the protective layer is a heat-resistant deformation resin having Tg outside the thermal recording temperature range. 4. A leuco dye as a coloring material is contained in the reversible thermosensitive recording layer.
The reversible thermosensitive recording sheet described.