JPH0430916B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to imaging materials. More particularly, the present invention relates to an image-forming material on which an image can be formed by a thermal head and conversely erased by water or steam. Traditionally, reversible imaging materials have been described in U.S. Pat.
No. 3560229, No. 3666525, No. 4028118 and No.
No. 3244548 and Japanese Patent Application Laid-open No. 191190/1983. 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,
lines 64-68). 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 salts of p-quinone and dihydrobenzene compounds are thus 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 formed image is blue,
They are green, red, orange and yellow. As a result of extensive research into reversible image formation, the present inventors have discovered that a reversible image forming system is developed in which a layer consisting of a color former, a color developer, and a binder is provided on one side of a base material, and an overcoat layer is provided on the layer. In the image forming material, the color former is represented by the following general formula, the color developer is composed of at least one of gallic acid and phloroglucinol, and an image is formed by a thermal head, and vice versa. It has been possible to provide a reversible image-forming material characterized in that the image formed can be erased with water or water vapor. [Here, R ₁ is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, and R ₂ is an amino group (

[Formula] R ₃ is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms,
R ₄ represents a phenyl group, an alkyl group-substituted phenyl group, or a halogen-substituted phenyl group), X is hydrogen,
A lower aliphatic alkyl group having 1 to 4 carbon atoms, m is an integer of 1 or 2, Y is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 or 2. ] The image forming material of the present invention allows image formation to be performed repeatedly using a thermal head. The advantages of the invention are as follows. First, it is a reversible image-forming material that can form high-density and clear images 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 an 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 at least one coloring agent represented by the following general formula and at least one of phloroglycinol and gallic acid.
The present invention provides a reversible imaging material having an overcoat layer on a layer composed of a color developer and a suitable binder. [Here, R ₁ is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, R ₂ is an amino group, (

[Formula] R ₃ is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms,
R ₄ represents a phenyl group, an alkyl group-substituted phenyl group, or a halogen-substituted phenyl group), X is hydrogen,
A lower aliphatic alkyl group having 1 to 4 carbon atoms, m is an integer of 1 or 2, Y is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 or 2. ] When the base material (resin-coated base paper) is a base paper coated with a polymeric material such as polyethylene on both sides or the coated side, a record composed of three components, a color former, a color developer, and a binder, is formed on one side of the coated base paper. The recording layer is coated with an overcoat layer of a suitable transparent film, for example polystyrene, on top of the recording layer. The recording layer of the coated base paper forms an image using heat from a thermal head of a thermal printer, thermal recording facsimile, or the like.
The image is erasable by exposing the imaging material to water or steam;
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. and ethylene-propylene copolymers,
These include linear polyesters such as polystyrene, polybutylene, polypentene, polyacrylic esters, polyethylene terephthalate, polycarbonates, polyamides such as nylon, cellulose esters, and copolymers of the above-mentioned monomers such as ethylene-vinyl acetate copolymers. 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 coloring agent of the present invention has the general formula [Here, R ₁ is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, R ₂ is an amino group, (

[Formula] R ₃ is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms,
R ₄ represents a phenyl group, an alkyl group-substituted phenyl group, or a halogen-substituted phenyl group), X is hydrogen,
A lower aliphatic alkyl group having 1 to 4 carbon atoms, m is an integer of 1 or 2, Y is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 or 2. ] It can be expressed as 3-{N-methyl-N-(p-methylphenyl)
amino}-6-methyl-7-phenylamino-fluorane, 3-{N-ethyl-N-(p-methylphenyl)
amino}-6-methyl-7-phenylamino-fluorane, 3-{N-methyl-N-(p-methylphenyl)
amino}-6-tert.butyl-7-(p-chlorophenyl)amino-fluorane, 3-{N-methyl-N-(p-methylphenyl)
amino}-6-tert.butyl-7-(p-methylphenyl)amino-fluorane, 3-(N-ethyl-N-phenylamino)-6-
Methyl-7-{N-ethyl-N-(p-methylphenyl)amino}-fluorane, 3-{N-propyl-N-(p-methylphenyl)amino}-6-methyl-7-{N-methyl-N
-(p-methylphenyl)amino}-fluorane 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, 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 coloring agent, developer, and binder during coating, there is no restriction at all in adding 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 3-{N-ethyl-N-(p
-methylphenyl)amino}-6-methyl-7-
Phenylamino-fluorane 2.0 parts, phloroglucinol 2.0 parts, hydroxypropyl cellulose
A recording layer solution was prepared by dissolving 3.0 parts. The resulting solution was applied onto a 64 g/m ² base paper coated with polyethylene using a Mayer bar 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 coated on the previously obtained black recording layer using a Mayer bar, and then
Dry in an oven at °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 surface of the product obtained was as white as the base 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 3-{N-ethyl-N-(p
-methylphenyl)amino}-6-methyl-7-
3-{N- instead of phenylamino-fluorane
Methyl-N(p-methylphenyl)amino}-6-
Methyl-7-phenylamino-fluorane,
A reversible image forming material was prepared in the same manner as in Example 1 using the recording layer solution as follows. Similarly, it was in a black state. Acetone/ethanol (1:1) mixed solvent 96.0 parts 3-{N-methyl-N(p-methylphenyl)amino}-6-methyl-7-phenylamino-fluoran 1.0 parts Phloroglucinol 1.0 parts Hydroxypropyl cellulose 2.0 parts Obtained The same printing and erasing as in Example 1 was repeated using the reversible image forming material obtained, and the effect was confirmed. Comparative Example 1 The coloring agent was 3-{N-ethyl-N-(p
-methylphenyl)amino}-6-methyl-7-
A coated paper having a black recording layer was obtained in the same manner as in Example 1 except that 2-phenylamino-3-methyl-6-diethylaminofluoran was used instead of phenylamino-fluoran. The coated paper obtained here is heated to
When it was kept in a constant temperature and humidity chamber at 40°C and 90% humidity for several minutes and then 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 tester 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 in which a layer consisting of a color former, a color developer and a binder is provided on one side of a resin-coated base paper, and an overcoat layer is provided on the layer, wherein the color former is one of the following general It is expressed by the formula,
A reversible image-forming material characterized in that the color developer comprises at least one of gallic acid and phloroglucinol, and an image can be formed with a thermal head, and conversely, the formed image can be erased with water or steam. [Here, R ₁ is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, R ₂ is an amino group, ([Formula] R ₃ is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, R ₄ represents a phenyl group, an alkyl group-substituted phenyl group, or a halogen-substituted phenyl group), X is hydrogen, a lower aliphatic alkyl group having 1 to 4 carbon atoms, m
is an integer of 1 or 2, Y is hydrogen or a lower aliphatic alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 or 2. ] 2 The color former is 3-{N-methyl-N-(p-methylphenyl)
amino}-6-methyl-7-phenylamino-fluorane, 3-{N-ethyl-N-(p-methylphenyl)
amino}-6-methyl-7-phenylamino-fluorane, 3-{N-methyl-N-(p-methylphenyl)
amino}-6-tert.butyl-7-(p-chlorophenyl)amino-fluorane, 3-{N-methyl-N-(p-methylphenyl)
amino}-6-tert.butyl-7-(p-methylphenyl)amino-fluorane, 3-(N-ethyl-N-phenylamino)-6-
Methyl-7-{N-ethyl-N-(p-methylphenyl)amino}-fluorane, 3-{N-propyl-N-(p-methylphenyl)amino}-6-methyl-7-{N-methyl-N
-(p-methylphenyl)amino}-fluorane Claim 1
Reversible imaging material as described in Section. 3. The reversible image forming material according to claim 1 or 2, wherein the binder is at least one of hydroxypropyl cellulose, cellulose acetate, and ethyl cellulose. 4. The reversible image forming material according to claim 1, 2 or 3, wherein the overcoat layer is polystyrene.