JPH0429883A - Image forming medium - Google Patents

Abstract

PURPOSE:To form a multicolor image which can be reversibly formed or erased by a method wherein a coloring agent which can color or decolor by heat is arranged in the form of a large number of small dots or lines. CONSTITUTION:A coloring agent coloring by a 1 - 100 msec. heating, decoloring by a long-time heating, and having different hues is arranged in a matrix or stripe form at intervals of 2 mm or less to form a coloring agent layer in an image forming medium. The coloring agent layer is formed by arranging fine dots of dyes of Magenta M, Yellow Y, Cyan C, and Black B and a color former containing a developing and reducing agent in a matrix form. The reversible coloring agent layer forms a color image by being heated at 300 deg.C or higher for 1 - 10 msec. This image can be erased by being heated at 100 - 200 deg.C for 1 sec. or longer. The image can be repeatedly formed and erased. As the reversible coloring agent layer, a composition containing an amphoteric compound and a leuco compound is used. The amphoteric compound is a salt of a compound containing at least one of phenol hydroxyl group and carboxyl group, and amino group, as shown by a formula I, and an aliphatic amine. In the formula, X represents hydroxyl group or carboxyl group, and R represents hydrogen atom or hydroxyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an imaging medium having a reversible colorant layer;
More particularly, the present invention relates to the above image forming medium for forming multicolor images.

[Prior Art and Problems] A technique of forming a full-color image by arranging coloring agents such as yellow, magenta, and cyan in a large number of minute dots or lines is well known.

Such full-color images have traditionally been used in various printed materials, but as the amount of information has increased in recent years, they have become more likely to appear and disappear reversibly due to cost issues and paper disposal issues. The formation of a full-color image, that is, the formation of an image using a coloring agent that can be reversibly colored and erased, is
It has been desired in a variety of applications.

Colorants themselves that change color and fade due to temperature changes are already known for such purposes, but when forming a full color image by arranging them in minute dots or lines as described above, it is necessary to use colorants at minute intervals. It has not yet been put to practical use because it is difficult to accurately control the temperature of adjacent points or lines to develop and erase color.

Therefore, an object of the present invention is to provide an image forming medium in which a full color image that can be reversibly generated and erased is formed by arranging a colorant that can be colored and erased in a large number of minute dots or lines. It is in.

[Means for Solving the Problems] In view of the above-mentioned problems, the present inventors have conducted intensive research and found that the above-mentioned object of the present invention is to develop a color by heating for 1 to 100 milliseconds,
A coloring agent that discolors by heating for a longer time,
It has been found that this can be achieved by providing an image forming medium having a colorant layer in which colorants having different hues are arranged in a matrix or stripe pattern at intervals of 2 mm or less.

The present invention will be explained in more detail below.

FIG. 1 shows a sheet having a portion of the image forming medium of the present invention, and FIG. 2 is an enlarged view of a portion of the image forming medium. According to FIG. 2, the colorant layer is formed by arranging minute dots of a coloring agent containing magenta, yellow, cyan, and black dyes and the color developer/subtractor of the present invention in a matrix. Such an arrangement may be a stripe pattern or any other arrangement. Also,
Hues can also be combined arbitrarily.

The reversible colorant layer in the present invention is thermal energy (old)
For example, a colored image (including characters) is formed by heating at a high temperature, preferably 300° C. or higher, for a short time (1 millisecond to 100 milliseconds, preferably 1 to 10 milliseconds). This image is created using another thermal energy (h2), i.e. a low temperature (humidity near or above the melting point of the developer, e.g. 100-2
00° C.) for a long time, preferably 1 second or more, and when the thermal energy (old) is applied again to the colorant layer from which the image has been erased, an image is formed again. Formation and erasure of this image can be repeated. This colorant layer maintains an image forming state or an image erasing state unless thermal energy is applied to it. The background after erasing the formed image is comparable to the condition of the background before image formation, and is excellent as a reversible colorant layer.

Specifically, the reversible colorant layer used in the present invention is an amphoteric colorant having at least one of phenolic water 111!4 and a carboxyl group, and having an amine group as a functional group or as a part of a salt compound. A composition comprising a compound and a leuco compound is preferred, and in particular, a composition comprising a leuco compound, in which the amphoteric compound has at least one of a phenolic hydroxyl group and a carboxyl group and an amino group and is represented by the following general formula [1], or at least A salt or complex salt of a compound having one phenolic hydroxyl group and/or carboxyl group and an aliphatic amine is preferred.

[In the formula, X represents a hydroxyl group or a carboxyl group,
R represents a hydrogen atom or a hydroxyl group. ] In the present invention, the amphoteric compound having at least one of a phenolic hydroxyl group and a carboxyl group and an amino group as a functional group or as a part of a salt compound preferably includes:
At least one of a phenolic hydroxyl group and a carboxyl group
Examples include a compound having at least one amino group and represented by the general formula [1], or a salt or complex salt of a compound having at least one phenolic hydroxyl group and/or carboxyl group and an aliphatic amine.

Specifically, the compounds represented by the above general formula [1] include 2-aminophenol, 3-amitsuquenol, 4-
Aminophenols such as aminephenol, aminobenzoic acids such as 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, 2hydroxy-3-aminobenzoic acid,
2-amino-3-hydroxybenzoic acid, 2-amino-4
-Hydroxybenzoic acid, 2-hydroxy-4-aminebenzoic acid, 2-hydroxy-6-aminobenzoic acid, 3-amino-4-hydroxybenzoic acid, 3-hydroxy-5-
Examples include aminobenzoic acid.

Further, as the compound having at least one phenolic hydroxyl group and/or carboxyl group that forms a salt or complex salt of a compound having at least one phenolic hydroxyl group and/or carboxyl group and an aliphatic amine, preferably the following general formula is used. Examples include compounds represented by [A] or [B] and ester compounds of these compounds.

(In the formula, n represents an integer of 1 to 3, preferably 2 or 3.) 0OH (In the formula, R1 represents a hydrogen atom or a methyl group, and nl represents an integer of O to 6.) Specific examples of the compound represented by the general formula [A] include the following J:

n=1; 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, etc. n=2: 3.4-dihydroxybenzoic acid 3.5-dihydroxybenzoic acid 2.3-dihydroxybenzoic acid 2.4 -dihydroxybenzoic acid 2.5-dihydroxybenzoic acid 2.6-dihydroxybenzoic acid 3.6-dihydroxybenzoic acid 4.5-dihydroxybenzoic acid 4.6-dihydroxybenzoic acid 4-hydroxysalicylic acid 5-hydroxysalicylic acid etc. n- 3; Gallic acid, etc. Specific examples of ester compounds of the compound represented by the above general formula [A] include hexyl gallate, hebutyl gallate, octyl gallate, nonyl gallate, decyl gallate, and undecyl gallate. , lauryl gallate, tridecyl gallate, te-1-radecyl gallate, pentadecyl gallate, cetyl gallate, heptadecyl gallate, stearyl gallate, and the like.

Further, specific examples of the compound represented by the above general formula [B] include the following.

・2,2-bis(/I-hydroxyphenyl)ethanoic acid ・2,2-bis(4-hydroxyphenyl)propionic acid ・3,3-bis(4-hydroxyphenyl)propionic acid ・4,4-bis( 4-hydroxyphenyl)butanoic acid, 4,4-bis(4-hydroxyphenyl)butanoic acid, 5,5-bis(4-hydroxyphenyl)pentanoic acid, 5,5-bis(4-hydroxyphenyl)hexanoic acid・6.6-bis(4-hydroxyphenyl)heptanoic acid ・7.7-bis(4-hydroxyphenyl)hebutanoic acid ・8,8-bis(4-hydroxyphenyl)octanoic acid ・7.7-bis( 4-hydroxyphenyl)octanoic acid/8,8-bis(4-hydroxyphenyl)nonanoic acid In the present invention, the aliphatic amines forming the salt or complex salt include octylamine, nonylamine,
Decylamine, undecylamine, laurylamine, tridecylamine, tetradecylamine, pentadecylamine, heptadecylamine, cetylamine, stearylamine, hexylamine, heptylamine, benzylamine, 2-phenylethylamine, 3-phenylpropylamine, 4-phenylbutylamine, 5-phenylpentylamine, 6-phenylbutylamine, 7-phenylbutylamine, nylheptylamine, 8-phenyloctylamine, 9-
7 enylnonylamine, 10 phenyldecylamine, 1
1-phenylundecylamine, 12-phenyldodecylamine, 13 phenyltridecylamine, 14-phenyltetradecylamine, 15-7enylpentadecylamine, 16-phenylhexadicylamine, 17-phenylheptadecylamine, 18 -Phenyloctadecylamine, methylbenzylamine, 2-triethylamine, 3-tolylpropylamine, 4-tolylbutylamine, 5-tolylpentylamine, 6-tolylhexylamine, 7-tolylhebutylamine, 8-tolyloctylamine, 9-Tolylnonylamine, 10-Tolyldecylamine, 11-Tolylundecylamine, 12-Tolyldodecylamine, 13-Tolyltridecylamine, 1
4-Tolyltetradecylamine, 15-tolylpentadecylamine, 16-tolylhexapsylamine, 17-tolylheptadecylamine, 18-tolyl octadecylamine, chlorobenzylamine, 2-chlorophenylethylamine, bromobenzylamine, 2-bromophenyl Examples include ethylamine, methoxybenzylamine, and ethoxybenzylamine.

In the present invention, the above salts or complex salts are preferably salts of dihydrobenzoic acid represented by the following general formula "2" and higher aliphatic amines having an alkyl group having 8 or more carbon atoms, and salts of the following general formula [3]. ] Salts of gallic acid and higher aliphatic amines represented by the following general formula [41], or salts of dihydroxybenzoic acid and aliphatic amines represented by the following general formula [41], gallic acid represented by the following general formula [5] and an aliphatic amine, bis(hydroxyphenyl)acetic acid represented by the following general formula [6], or a salt of bis(hydroxyphenyl)butyric acid and a higher aliphatic amine, 2 represented by the following general formula [7] Salts of aliphatic carboxylic acids and aliphatic amines having hydroxyphenyl groups, or complex salts of gallic acid esters and higher aliphatic amines represented by the following general formula [8] may be mentioned.

(In the formula, R4 represents an alkyl group having 8 or more carbon atoms.) (In the formula, R5 represents an alkyl group having 8 or more carbon atoms.) (In the formula, R6 represents a hydrogen atom, an alkyl group, or a halogen atom. ,
or an alkoxy group, R2 is 1 or 2, R3 is 1 to 18
represents an integer. ) (In the formula, R7 represents a hydrogen atom, an alkyl group, a halogen atom, or an alkoxy group, and R4 represents an integer from 1 to 18.) R.

(In the formula, R8 represents a hydrogen atom or a methyl group, R9 represents an alkyl group having 8 or more carbon atoms.) (In the formula, Rho represents a hydrogen atom or a methyl group, and RH represents a hydrogen atom, an alkyl group, a halogen atom, or an alkyl group. group, R5 represents an integer of O to 6, and R6 represents an integer of 1 to 18.) (However, R12 and R+3 each represent an alkyl group having 8 or more carbon atoms.) In the reversible colorant layer of the present invention Various known leuco compounds can be used together with the amphoteric compound, and for example, the following dyes can be used depending on each hue.

Black dye Blue dye Red dye Yellow dye In the present invention, the above-mentioned dyes are combined with the developer/subtractor to form fine dots with a dot diameter of 2 mm or less, preferably 10 to 100 μm, and dot spacing of 2 mm or less. , preferably 0 to 100 .mu.I, arranged in a matrix or in stripes, on the substrate.

Further, the reversible colorant layer of the present invention can further contain a binder, and such a binder can be a commonly used polymeric material that is soluble in water or an organic solvent.

Specific examples of such polymer materials include polyvinyl alcohol, methyl cellulose, ethyl cellulose, cellulose acetate, polystyrene, polyvinyl chloride, linear saturated polyester, polymethyl methacrylate, polyethyl methacrylate, and other methacrylic resins alone. Alternatively, thermoplastic resins such as copolymers, polyurethane, polybutyral, and nitrocellulose can be used.

The content of each component as described above in the colorant layer of the present invention is 0.1 to 1 part by weight of the leuco compound per 1 part by weight of the amphoteric compound of the present invention, and preferably 2 parts by weight or less of the binder.

Next, as a method for coating the recording layer of the present invention on a support, specifically, the binder is dissolved in a coating liquid uniformly dispersed or dissolved in water or an organic solvent, and if necessary, A recording layer coating solution containing a thickener, white pigment, etc. as a liquid property improver is coated on an opaque substrate such as paper, plastic film or sheet by bar coating, blade coating, air knife coating, gravure coating, etc. A method is used in which the recording layer is provided by coating and drying by a coating method such as roll coating. At this time, the coating amount after drying is 4 to 100/m
2 is preferred.

Further, on the recording layer made of the leuco compound, the amphoteric compound of the present invention, and the binder on the support, it is possible to improve thermal head matching properties (resistance adhesion to the thermal head, sticking) or to impart durability to the recording layer. Even if a protective layer is provided for this purpose, the characteristics of the recording medium of the present invention will not be impaired.

For example, as a protective layer component, a combination of a filler such as a colorless inorganic pigment or wax and a thermoplastic resin used as a binder for the recording layer, a thermosetting resin, or an ultraviolet curing resin, such as methyl (meth)acrylate, etc. Acrylic acid-based polymers and the like are used.

The image forming or image erasing method according to the present invention is based on heat, and uses a thermal printer, a heat reflection copying device,
This can be carried out using a device such as a hot stamper or a heat roller.

Since the image forming medium of the present invention can reversibly develop and erase images, it can be applied to any application that requires the repeated formation and disappearance of multicolor images, such as various cards, A- It can also be used for printing by changing the color of important points on film for bar head projectors, etc.

[Effects of the Invention 1] As described above, by arranging a coloring agent that can be colored and erased by heating in a large number of minute dots or lines, as in the image forming medium of the present invention, a full color that can be reversibly generated and erased can be produced. Images can be formed.

[Brief explanation of drawings]

FIG. 1 shows a sheet partially containing the image forming medium of the present invention, FIG. 2 shows an enlarged view of a colorant layer in which minute dots are arranged in a matrix in the image forming medium of the present invention, and FIG. indicates a schematic cross-sectional view of the sheet in Figure 1. <Main reference numbers> Y...Yellow M...Magenta C...Cyan B...Black

Claims (1)

[Claims] A coloring agent that develops color when heated for 1 to 100 milliseconds and disappears when heated for a longer period of time, and is a coloring agent in which colorants having different hues are arranged in a matrix or stripe shape at intervals of 2 mm or less. Imaging media with layers.