JPH0430355B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to imaging materials. More specifically, a black image is formed by a thermal head,
On the contrary, it relates to an image-forming material whose formed image can be erased with water or water vapor.

Traditionally, reversible imaging materials have been described in U.S. Pat.
No. 3560229, No. 3666525, No. 4028118, No. 3244548, and Japanese Patent Application Laid-open No. 1981-191190.

The images formed in US Pat. No. 4,028,118 vary with temperature and are therefore not related to fixed images.

In the method described in U.S. Pat. No. 3,560,229, the appearance, erasure, and/or permanent fixation of the color developed from the coloring composition is achieved by adding a certain organic solvent to the coloring composition. controllable in the presence of water (column 1, 64
~68 lines). Organic solvents used in this process are glycols, glycol ethers, halogenated biphenyl or biphenyl ethers, aromatic or aliphatic ester type plasticizers and other low vapor pressure solvents.

crystal violet lactone, gallic acid,
A thermal copying sheet consisting of acetanilide, styrene-butadiene copolymer and toluene is disclosed in U.S. Pat. No. 3,666,525 (column 8,
lines 52-61). The image formed on the sheet is erased on contact with water, and this heat-sensitive composition requires the addition of a heat-melting substance.

U.S. Pat. Nos. 3,414,423 and 3,515,568 relate to methods of reusing thermal copying material by erasing images formed thereon. According to both methods, the colored double salt of the P-quinone compound and the dihydrobenzene compound is obliterated by the application of certain organic solvents or heat.

A multilayer sheet using a lactone color-forming compound and a phloroglucinol co-reactant is disclosed in U.S. Pat.
Disclosed in No. 3244548.

JP-A-58-191190 relates to a reversible heat-sensitive transparent film, and the images formed are blue, green,
red, orange and yellow.

As a result of intensive research into the formation of black images, the inventors of the present invention found that using resin-coated base paper as the base material,
A reversible image forming material comprising a layer consisting of a color former, a color developer and a binder on one side, and an overcoat layer on the layer, wherein the color former has a general formula: (Here R ₁ and R ₂ are ethyl or butyl groups,
X is fluorine or chlorine), i.e. 2-(O-chlorophenylamino)-6-dibutylaminofluoran, 2-(O-chlorophenylamino)-6-dibutylamino-fluoran and 2-( O-chlorophenylamino)-6-diethylaminofluorane, the color developer is comprised of at least one of gallic acid and phloroglucinol, and forms a black image with a thermal head, and reverses It was possible to provide a reversible image-forming material characterized in that an image formed thereon can be erased with water or steam.

An object of the present invention is to be able to repeatedly form black images using a thermal head.

The advantages of the invention are as follows.

First, it is a reversible image-forming material that can form a high-density and clear black image on resin-coated base paper.

Secondly, there are many types of recording paper using a thermal head, and it is a reversible image forming material that can be used repeatedly in consideration of resource saving.

Thirdly, it is a reversible image-forming material that can form a black image on the white background of resin-coated base paper.

The present invention will be explained in detail below.

The present invention provides resin-coated base paper with the general formula (Here R ₁ and R ₂ are ethyl or butyl groups,
X is fluorine or chlorine), i.e. 2-(O-
chlorophenylamino)-6-dibutylaminofluorane, 2-(O-fluorophenylamino)-
6-dibutylaminofluorane and 2-(O-
an overcoat on a layer consisting of at least one of chlorophenylamino)-6-diethylaminofluorane, at least one developer of phloroglucinol and gallic acid, and one suitable binder; A layered reversible imaging material is provided.

When the base material is a base material coated with a polymeric material such as polyethylene on both sides or the coated surface, a recording layer composed of three components, a color former, a color developer, and a binder, is coated on one side of the base material. Furthermore, an overcoat layer made of a suitable transparent film, such as polystyrene, is provided on the upper surface of this recording layer. The recording layer of the base material forms a black image by heat from a thermal head of a thermal printer, thermal recording facsimile, or the like. This image can be erased by exposing the image-forming material to water or steam, and when heat is applied to the image-forming material from which the image has been erased, an image is formed again. Formation and erasure of this image can be repeated any number of times. This image-forming material maintains an image-forming state or an image-erasing state unless exposed to water, steam, or heat. After erasing the formed image, the background is a plain white reversible image forming material without retaining any traces of the formed image.

Examples of the resins used for the resin-coated base paper of the present invention include the following. Polyethylene, polypropylene, polyisobutylene, etc., linear polyesters such as ethylene-propylene copolymers, polystyrene, polybutylene, polypentene, polyacrylic esters, polyethylene terephthalate, polycarbonates, polyamides such as nylon, cellulose esters, and other ethylene-vinyl acetate copolymers. and copolymers of the monomers mentioned above.

Preferably, polyolefins such as polyethylene, polypropylene, polyisobutylene, copolymers containing ethylene and propylene as main components, and mixtures thereof are used. More preferably, polyethylene is used.

Note that the base paper used may be ordinary plain paper.

The color former of the present invention has the general formula (Here R ₁ and R ₂ are ethyl or butyl groups,
X can be represented by fluorine or chlorine), i.e. 2-(O-chlorophenylamino)-
6-dibutylaminofluorane, 2-(O-fluorophenylamino)-6-dibutylaminofluorane, and 2-(O-chlorophenylamino)
-6-diethylaminofluorane, which can be used alone or in combination.

Furthermore, in addition to the color former of the present invention, the following color formers can also be used in combination. For example, 3,3-bis(4'-dimethylaminophenyl)-6-dimethylaminophthalide, 6-cyclohexylamino-2-methylfluorane, 2-chloro-6-diethylamino-3
-Methylfluorane, 6-dimethylamino-1,
3,4-trimethylfluorane, 3-(1-ethyl-2-methylindol-3-yl)-3-(4
-diethylamino-2-butoxyphenyl)phthalide, 3,3-bis(1-ethyl-2-methylindol-3-yl)phthalide, 9-diethylaminospiro(12H-benzo(a)xanthene-12,
1′(3′H)isobenzofuran-3′-one, 6-dimethylamino-2-dibenzylaminofluorane,
and the isomer 5-(1-ethyl-2-methylindol-3-yl)-5-(4-dimethylamino-
2-ethoxyphenyl)-5,7-dihydrofuro(3,4-b)pyridin-7-one and 7-(1-ethyl-2-methylindol-3-yl)-7-
(4-dimethylamino-2-ethoxyphenyl)-
5,7-dihydrofuro(3,4-b)pyridine-
Examples include 5-one.

Preferred color developers in the present invention are phloroglucinol and gallic acid.

Further, in the present invention, as the binder, polymeric materials that are soluble in commonly used organic solvents can be used, but in particular, hydroxypropyl cellulose,
Cellulose acetate, ethyl cellulose, and the like are preferred.

A homogeneous recording layer is obtained from a solution containing three components: a color former, a color developer, and a binder. Any solvent can be used as long as it dissolves the three components. Examples include acetone, methyl ethyl ketone, ethanol, toluene, ethyl acetate, 2-ethoxyethyl acetate, and the like.

In addition to the color forming agent, color developer, and binder during coating, there is no limitation to the addition of a thickener, white pigment, etc. as a liquid property improver. Examples of the coating method include a method of printing and coating the entire surface of the base material using a gravure coater, flexo coater, etc., or a method of printing and coating a portion of the base material using a gravure printer, flexo printer, etc.

The overcoat layer on the upper surface of the recording layer may be any transparent film material that is compatible with the recording layer, and polystyrene is particularly preferred.

Image formation according to the present invention is based on heat;
The recording device is a thermal printer or a heat reflection copying device. Image erasure is accomplished by maintaining the reversible imaging material in a humid atmosphere or by immersing it in water. More specifically, the material on which the image has been formed may be immersed in water for several minutes or brought into contact with a wet surface such as damp cloth or paper.

Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "parts" in the examples indicate parts by weight.

Example 1 1.0 part of 2-(O-chlorophenylamino)-6-dibutylaminofluorane in 95.0 parts of acetone,
A recording layer solution was prepared by dissolving 1.5 parts of phloroglucinol and 2.5 parts of hydroxypropylcellulose. The resulting solution was applied using a Mayer bar onto a 64 g/m ² base paper for photographic paper laminated with polyethylene and dried in a dryer at 60°C. The dried recording layer was black. Separately, an overcoat layer solution was prepared by dissolving 10 parts of polystyrene in 90 parts of toluene. This overcoat layer solution was applied onto the previously obtained black recording layer using a Mayer bar, and dried in a dryer at 60°C. The product obtained here remained black.

The product prepared as above was heated at a temperature of 40℃ and a humidity of 90%.
The black state of the recording layer was erased by keeping it in a constant temperature and humidity chamber for several minutes. The background of the product obtained was as white as the base paper for photographic printing paper itself.

When the thus obtained reversible image-forming material was printed from the recording layer side using a facsimile tester manufactured by Matsushita Electronic Components, a clear and high-density black printed image could be obtained. When similar erasing and printing were performed again, it was confirmed that the material had reproducibility and was extremely excellent as a reversible image forming material.

Example 2 The color former was replaced with 2-(O-chlorophenylamino)-6-dibutylaminofluoran in Example 1 and 2-(O-fluorophenylamino)-6-dibutylaminofluoran was used to form the recording layer. A reversible image forming material was prepared in the same manner as in Example 1 using the following solution formulations.

Acetone/ethanol (1:1) mixed solvent
94.0 parts 2-(O-fluorophenylamino)-6-dibutylaminofluorane 0.75 parts Phloroglucinol 1.75 parts Hydroxypropylcellulose 3.5 parts Printing was carried out in the same manner as in Example 1 using the obtained reversible image forming material. , we repeated the erasure and confirmed its effectiveness.

Example 3 The color former was replaced with 2-(O-chlorophenylamino)-6-dibutylaminofluoran in Example 1 and 2-(O-chlorophenylamino)-6-diethylaminofluoran was used. Same formulation,
A reversible imaging material was prepared by the method.

Using the obtained reversible image forming material, printing and erasing were repeated in the same manner as in Example 1 to confirm the effect.

Comparative Example 1 Same as Example 1 except that the color former was replaced with 2-(O-chlorophenylamino)-6-dibutylaminofluoran of Example 1 and 2-phenylamino-3-methyl-6-diethylaminofluoran was used. A coated paper with a black recording layer was obtained. The coated paper obtained here was kept in a constant temperature and humidity chamber at a temperature of 40°C and a humidity of 90% for several minutes, and when it was taken out, the black color of the recording layer had not been erased. Furthermore, no change was observed when the sample was maintained under the same conditions. This black coated paper was printed using a facsimile testing machine manufactured by Matsushita Electronic Components, but no further color development was observed due to the black background itself.

From the above, 2-phenylamino-3-methyl-
When 6-diethylaminofluorane was used as a coloring agent, no effect as a reversible image forming material could be obtained.

Claims (1)

[Scope of Claims] 1. A reversible image forming material comprising a layer consisting of a color former, a color developer and a binder on one side of resin-coated cardboard, and an overcoat layer on the layer, wherein the color former is 2- (O-chlorophenylamino)-6-
Dibutylaminofluorane, 2-(O-fluorophenylamino)-6-dibutylaminofluorane and 2-(O-chlorophenylamino)-6
- at least one type of diethylfluorane, the color developer comprising at least one type of gallic acid and phloroglucinol, which forms a black image with a heated head and conversely with water or a reversible image-forming material characterized in that it can be erased with water vapor. 2. Claim 1, wherein the binder is at least one of hydroxypropylcellulose, cellulose acetate, and ethylcellulose.
Reversible imaging material according to item 1 or 2. 3. The reversible image forming material according to claim 1, 2 or 3, wherein the overcoat layer is polystyrene.