JPH06219047A - Reversible thermal recording sheet - Google Patents

Abstract

PURPOSE:To provide a reversible thermal recording sheet enhanced in ultraviolet shielding capacity and thermal deformation resistance. CONSTITUTION:In a reversible thermal recording sheet wherein a reversible thermal recording layer capable of repeatedly performing recording and erasure is provided on a support and a protective layer using a thermal deformation- resistant resin as a binder is provided on the recording layer, an inorg. ultraviolet reflecting substance and an org. ultraviolet absorbing substance are added to at least either one of the reversible thermal recording layer and the protective layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible heat-sensitive recording sheet, and more particularly to a reversible heat-sensitive 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 thermochromic composition as a main component on a support such as paper, synthetic paper and plastic film have been conventionally used for electronic computers, facsimiles, labels, word processors, thermal It is widely used in printers, plotters, etc., and is highly evaluated for its stable recording characteristics, high image quality, and ease of device handling.

By the way, in recent years, in view of the cost associated with the increase in the amount of information, the problem of paper disposal and the problem of resource protection, it has been strongly demanded to promote the development of a reversible thermosensitive recording material capable of reversibly generating and deleting an image. As a material related to this, for example, JP-A-58-191190 and JP-A-
The disclosure is made in JP-A-60-193691 and US Pat. No. 3,666,525. The thermochromic composition used for such a reversible thermosensitive recording sheet generally comprises a color former and a color-developing substance (color-developing agent) for coloring and decoloring the color-developing agent by the difference in heat energy. As the color-developing agent, for example, a colorless or light-colored leuco dye having a lactone ring or the like is used, and as the color-developing / reducing agent, for example, at least one of a phenolic hydroxyl group or a carboxyl group, and an amino group is a functional group. Alternatively, an amphoteric compound having a part of a salt compound is used.

[0004]

However, this type of heat-sensitive recording material has less light resistance in the image area and the background area than general heat-sensitive recording paper (when exposed to a fluorescent lamp or sunlight for a long period of time). It does not have sufficient characteristics for practical use, such as a decrease in density in the image area, a significant discoloration in the background area, and an unclear image.

That is, these reversible thermosensitive recording sheets were not able to sufficiently block ultraviolet rays emitted from sunlight and fluorescent lamps. These sheets are used repeatedly, and are more frequently exposed to sunlight, fluorescent lamps, etc. than general thermal recording paper, so the density of the image area is reduced and the discoloration of the background area due to sunlight etc. Was remarkable, and did not have sufficiently satisfactory light resistance.

In addition, when an organic ultraviolet absorber is added to improve light resistance, the effect cannot be obtained unless a considerably large amount of ultraviolet absorber is added. Further, since the binder is weakly bound due to the large amount of addition, the layer is destroyed by repeated printing, and the thermal recording layer falls off from the support, so that the performance is not sufficiently satisfactory. Further, problems such as deformation and breakage of the binder due to repeated thermal printing have occurred.

An object of the present invention is to provide a reversible thermosensitive recording sheet which solves the problems of the prior art and has an improved ultraviolet ray shielding ability and an improved thermal deformation resistance.

[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, characterized in that an inorganic ultraviolet reflecting substance and an organic ultraviolet absorbing substance are contained in at least one layer of the reversible thermosensitive recording layer or the protective layer. It can be achieved by using a reversible thermosensitive recording sheet.

[0009]

The above is a result obtained by the inventors of the present invention through intensive studies to achieve the above-mentioned object, and ultrafine particles of zinc oxide, titanium oxide, or the like as an inorganic ultraviolet reflecting substance are contained in the protective layer binder. Benzophenone-based compound or benzotriazole-based compound as an organic UV-absorbing substance in the heat-sensitive recording layer, or ultrafine particles of inorganic UV-reflecting substance such as zinc oxide or titanium oxide It has been found that the problem can be solved by containing a benzophenone compound or a benzotriazole compound, which are ultraviolet absorbing substances, in the protective layer, and by using a heat-resistant deformation resin whose Tg is outside the thermal recording temperature range as the binder. It is a thing.

By simultaneously using the organic UV absorbing substance and the inorganic UV reflecting substance, the light resistance of the reversible thermosensitive recording sheet can be further improved. Furthermore, by using a heat-resistant deformation resin whose Tg is outside the thermal recording temperature range as a binder,
It is possible to 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 G 1215 (with an antistatic layer manufactured by Toyobo Co., Ltd.) was used as a support, and the surface thereof was coated with a heat-sensitive recording material having the following composition with a wire bar coater. It was dried at ℃ for 30 minutes.

Coloring dye (TH-105 manufactured by Hodogaya Chemical Co., Ltd.) 2.0 parts by weight Developer and developer (gallate / octadecylamine complex) 12.0 parts by weight Acrylic resin (Dianal BR-80, manufactured by Mitsubishi Rayon Co., Ltd.) ) 20% toluene solution… 20.0 parts by weight UV absorber (SEESORB 701, manufactured by Sipro Kasei Co., Ltd.)… 0.5 parts by weight Stearic acid amide 2.0 parts by weight Solvent (toluene)… 63.5 parts by weight Next, the sample obtained above A protective layer coating solution having the following composition having a thickness of about 1 to 2 μm was applied to the surface of the above with a wire bar coater to form a protective layer.

Heat-resistant methacrylic resin (Dianal BR-179, manufactured by Mitsubishi Rayon Co., Ltd.) 10% toluene solution… 67.0 parts by weight Calcium carbonate (Brilliant-15 manufactured by Shiraishi Industry Co., Ltd.)… 5.0 parts by weight Titanium oxide (MT -100S Teika Co., Ltd .... 3.0 parts by weight Zinc stearate ... 1.0 parts by weight Toluene ... 24.0 parts by weight

[0015]

Example 2 UV absorber SEEDSORB in Example 1
A reversible thermosensitive recording layer was formed in the same manner as in Example 1 except that 701 was not added, and a protective layer coating solution having the following composition was applied to the surface of the layer using a wire bar coater to a thickness of about 1 μm. , A protective layer was formed.

Heat-resistant methacrylic resin (Dianal BR-179, manufactured by Mitsubishi Rayon Co., Ltd.) 10% toluene solution: 66.0 parts by weight Calcium carbonate (Brilliant-15 manufactured by Shiraishi Industry Co., Ltd.): 5.0 parts by weight Titanium oxide (MT -100S Teika Co., Ltd.) 2.0 parts by weight UV absorber (SEESORB 701, manufactured by Cypro Kasei Co., Ltd.) 2.0 parts by weight Zinc stearate ... 1.0 parts by weight Toluene 24.0 parts by weight

[0017]

Comparative Example 1 A sample of Comparative Example 1 was prepared in the same manner as in Example 1 except that titanium oxide in the protective layer was not added.

[0018]

Comparative Example 2 In the same manner as in Example 1, a reversible thermosensitive recording material having the following composition was coated on a support and dried.

Coloring dye (TH-105 manufactured by Hodogaya Chemical Co., Ltd.) 2.0 parts by weight Developer and developer (gallic acid / octadecylamine complex) 12.0 parts by weight Acrylic resin (Dianal BR-80, manufactured by Mitsubishi Rayon Co., Ltd.) ) 20% toluene solution ... 20.0 parts by weight Ultraviolet absorber (SEESORB 701, manufactured by Cypro Kasei Co., Ltd.) ... 4.0 parts by weight Stearic acid amide ... 2.0 parts by weight Solvent (toluene) ... 63.5 parts by weight Next, obtained above. The surface of the sample was coated with a coating solution for a protective layer having the following composition using a wire bar coater so as to have a thickness of about 1 μm to form a protective layer.

Acrylic resin (Dianal BR-88, manufactured by Mitsubishi Rayon Co., Ltd.) 20% toluene solution… 40.0 parts by weight Calcium carbonate (Brilliant-15 manufactured by Shiraishi Industry Co., Ltd.)… 8.0 parts by weight Zinc stearate… 2.0 parts by weight Parts Toluene ... 50.0 parts by weight The samples obtained in the above Examples and Comparative Examples were subjected to the various tests described below, and the results obtained are shown in Table 1.

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 background part at that time was measured by a Macbeth densitometer. The display of the results in the table shows that the larger the value, the higher the printing density and the better the light resistance.

Decoloring test : After exposing the image part and the background part colored by the same thermal printer as above to sunlight for 20 hours, the erasing state of the image using an infrared heating type heat roll at 120 ° C. It was confirmed.

Thermal deformation test : Printing with the same thermal printer as above and erasing with an infrared heating type heat roll at 110 ° C. were repeated 50 times, and the condition of the sample surface and blocking were evaluated. In the display of the results in the table, ○ and × indicate “no change” and “the protective layer was destroyed”, respectively.

[0024]

[Table 1]

From the results shown in Table 1, by using an organic ultraviolet absorber and an inorganic ultraviolet reflecting substance together and using a heat-resistant deformation resin as a binder, light resistance, durability against deformation by thermal printing, and blocking resistance. It can be seen that the property is extremely improved.

[0026]

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, A reversible thermosensitive recording sheet comprising a protective layer using a heat-resistant deformation resin as a binder on the recording layer, wherein an inorganic UV-reflecting property is present in at least one of the reversible thermosensitive recording layer and the protective layer. The reversible thermosensitive recording sheet is characterized by containing a substance and an organic ultraviolet absorbing substance, thereby solving the problems of the prior art, improving the ultraviolet shielding ability, and improving the heat distortion resistance. It was possible to provide a reversible thermosensitive recording sheet having improved temperature.

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

Claims (3)

[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 reversible thermosensitive recording layer or in the protective layer, at least one layer contains an inorganic UV-reflecting substance and an organic UV-absorbing substance. 2. The reversible thermosensitive recording sheet according to claim 1, wherein a heat-resistant deformation resin having a Tg outside the thermal recording temperature range is used as a binder for the protective layer. 3. The reversible thermosensitive recording sheet according to claim 1, wherein a leuco dye is contained as a coloring material in the reversible thermosensitive recording layer.