JPH10329420A - Reversible thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible thermal recording material without raising texture density and without lowering erasing performance even in the case of repeatedly using it. SOLUTION: In the reversible thermal recording material having a dye precursor for emitting electron to become dye add electron receptive compound on a support in such a manner that color developing state and discoloring state occurs according to heat treating temperature condition to form an image, the recording material comprises hydroxyphenylbenzoic acid or its derivative, organic amino compound, and aliphatic phenon compound. And, the material preferably comprises compound having long chain alkyl group including 12 carbon atoms or more.

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 material capable of repeatedly displaying and erasing a visible image.

[0002]

2. Description of the Related Art Magnetic cards and IC cards are used for various prepaid cards. However, since the recorded contents cannot be directly viewed, it is not possible to easily check the amount of payment or the balance remaining, and guarantee the contents to the user. Was difficult. Therefore, studies are being made on a recording material or a recording method capable of performing visual recording and erasing the recording. Above all, a method capable of forming a dye image from the viewpoint of visibility is expected.

As a reversible thermosensitive recording material capable of forming a dye image, there is known a recording material in which a leuco dye having a lactone ring portion emits electrons, whereby the lactone ring is opened to form a color. The reversible recording material develops color when the recording layer is heated to a temperature T1, and cools rapidly to fix the color development state. After heating again to the temperature T2 (T2 <T1), the color disappears when gradually cooled.

JP-A-2-188293 discloses a reversible thermosensitive recording medium provided with a recording layer mainly comprising a leuco dye, a developer and a color reducing agent which develops or reduces the color by thermal reaction, and a binder. Have been. In this publication, coloring and decoloring are repeated by utilizing the difference in the reaction rate between an acid and a base.

JP-A-4-247895 discloses a reversible thermosensitive recording material provided with a recording layer mainly composed of a leuco dye, a developer, which is a phosphonic acid having a long-chain alkyl group, and a binder. ing. In this publication, the color developer has a cohesive force due to its structure, and the color developer and the leuco dye are separated from contact with and separated from each other, whereby coloring and decoloring are repeated.

[0006]

However, the printability of the reversible thermosensitive recording medium disclosed in JP-A-2-188293, which is the former, is low, so that the recorded print disappears. Further, when printing and erasing are repeated, the erasing performance is degraded and the written print remains. The reversible thermosensitive recording material disclosed in JP-A-4-247895, which is the latter, increases the background density and colorizes the display surface when printing and erasing are repeated. Then, the erasing performance is degraded, and after-writing of the written print occurs.

As described above, there is a problem to be solved in a recording medium capable of repeatedly recording and erasing while forming a dye image. An object of the present invention is to provide a reversible thermosensitive recording material in which the background density does not increase even after repeated use and the erasing performance does not decrease.

[0008]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a dye precursor and an electron-accepting compound which emit electrons and become a dye on a support, and the color-developed state and the decolored state are changed depending on the heat treatment temperature conditions. A reversible thermosensitive recording material which forms an image to form a reversible thermosensitive recording material, wherein the reversible thermosensitive recording material contains hydroxyphenylbenzoic acid or a derivative thereof, an organic amino compound, and an aliphatic phenone compound. It is preferable to contain a compound which is a thermal recording material and has a long-chain alkyl group having 12 or more carbon atoms.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a dye precursor used in the present invention, a leuco dye having a lactone ring in its molecular structure can be used. Leuco dyes have the property of emitting electrons and opening the lactone ring to form a color. When electrons are supplied, the lactone ring is closed again and the color is erased. The color developed depends on the molecular structure of the leuco dye.

Specifically, crystal violet lactone, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-3-
Phthalide compounds such as yl) -4-azaphthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, and 3-diethylamino-6-methyl-
7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 2- (2-chloroanilino) -6-diethylaminofluoran, 2- (2-chloroanilino) -6-dibutylaminofluor Oran, 2-
Anilino-3-methyl-6- (N-ethylisopentylamino) fluoran, 3-cyclohexylmethylamino-6-methyl-7-anilinofluoran, 3-benzylethylamino-6-thimer-7-anilinofur Oran,
3-diethylamino-6-chloro-7-anilinoflurane, 3-methylpropylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-thimer-7
-Fluoran compounds such as xylidinofluoran.

As the electron accepting compound, a hydroxyphenylbenzoic acid or a derivative thereof is used as a color-reducing agent that reacts with a dye precursor. Specifically, 4-hydroxyphenylbenzoic acid, 4- (4-hydroxyphenyl) benzoic acid, 4- (4-hydroxyphenoxy) benzoic acid, 2- (4-hydroxybenzoyl) benzoic acid,
-(4-hydroxy-3-phenylbenzoyl) benzoic acid, 3- (4-hydroxyphenyl) benzoic acid, 2-
(4-hydroxyphenyl) benzoic acid, 4- (3,4-
Dihydroxyphenyl) benzoic acid, 4- (2,3-dihydroxyphenyl) benzoic acid, 4- (2,4-dihydroxyphenyl) benzoic acid, 3- (3,4-dihydroxyphenyl) benzoic acid, 2- (3 4-dihydroxyphenyl) benzoic acid, 4- (4-hydroxybenzyl) benzoic acid, 4- (4-hydroxybiphenyl) benzoic acid, and the like.

The reversible thermosensitive recording material of the present invention can improve the contrast by containing an organic amino compound. Examples of the organic amino compound include, for example, aliphatic amines such as laurylamine, cetylamine, stearylamine, and eicosylamine, methylethylamine, thymerpropylamine, methylbutylamine, methylhexylamine, didodecylamine, trimethylamine, triethylamine, and dimethylethylamine. And lower amines such as dibenzylamine, tribenzylamine, alanine, phenylalanine, and aromatic amines such as triphenylguanidine; and cyclic amines such as pyridine, piperidine and piperazine.

As the aliphatic phenone compound used in the reversible thermosensitive recording material of the present invention, compounds represented by the following general formula 1 can be mentioned. The aliphatic phenone compound acts as a decolorizing accelerator, and when erasing a print, erases so that the erase density and the background density become substantially equal.

[0014]

## STR1 ## _R-CO-C 6 _{H 5,} where, R is an alkyl group having 10 or more carbon atoms.

The compounds having a long-chain alkyl group having 12 or more carbon atoms preferably used in the present invention include aliphatic carboxylic acids, aliphatic amides, alcohols, ketones, aliphatic anilides, aliphatic urea compounds and the above-mentioned compounds. Derivatives of the compounds are mentioned. It may have a hydroxyl group, a halogen group, a phenol group or the like as a functional group. Specifically, for example, lauric acid, hydroxylauric acid, palmitic acid, hydroxypalmitic acid, stearic acid, hydroxystearic acid, dihydroxystearic acid, behenic acid, lauric amide, hexadecanoic amide, stearic amide,
Examples include behenic acid amide, lauryl alcohol, cetyl alcohol, stearyl alcohol, lauron, stearone, myristic anilide, stearic anilide, n-tetradecyl urea, and n-stearyl urea.

The above-mentioned mixture comprising the dye precursor, the electron accepting compound, the organic amino compound and the aliphatic phenone is dispersed in a polymer binder, and then, as a recording layer on a support such as paper, synthetic paper, plastic film or the like. Applied. It is preferable to mix the above-mentioned compound having a long-chain alkyl group having 12 or more carbon atoms in the mixture.

As the polymer binder, a resin having good transparency and film forming properties and high heat resistance is used. For example, polymethacrylic acid ester, polyacrylic acid ester or a copolymer thereof, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-vinyl acetate-alcohol copolymer Polymers, other vinyl acetate compounds, vinyl chloride copolymers, polyvinylidene chloride, vinylidene chloride copolymers, polyvinyl alcohol, polyester, polyamide, polyurethane,
Polystyrene, acrylonitrile-styrene copolymer,
Acrylonitrile-butadiene-styrene copolymer is preferred.

The compounding ratio is 1 part by weight of leuco dye or 1 part of hydroxyphenylbenzoic acid or its derivative.
0-100 parts by weight, preferably 15-50 parts by weight, the organic amino compound is 10-80 parts by weight, preferably 10-80 parts by weight.
40 parts by weight, the aliphatic phenone compound is 1 to 20 parts by weight,
Preferably 3 to 10 parts by weight, the polymer binder is 10 to 10 parts by weight.
100 parts by weight, preferably 20 to 40 parts by weight.

In the present invention, a protective layer can be provided on the recording layer in order to improve the repetition durability and the matching property with the thermal head. Examples of the protective film include polyethylene terephthalate, polyetherimide, polyetheretherketone, polysulfone, polyphenylenesulfide, polyacrylate, polyethersulfone, polycarbonate, polyethylenenaphthalate, polyimide, acrylic resin, ultraviolet curable resin, and electron beam curable resin. A resin with high heat resistance is used.

Further, in order to improve the heat-resistant storage stability and thermal stability of the color-developed state, prevent discoloration and fading by light, and improve sensitivity, a stabilizer, a sensitizer, an ultraviolet absorber, a dispersant, etc. Can be contained.

For example, the reversible thermosensitive recording material of the present invention has a structure in which a recording layer in which various compounds are dispersed in a polymer binder and a protective layer are sequentially laminated on a synthetic resin base sheet such as polyethylene terephthalate. .

The reversible thermosensitive recording material of the present invention is heated (T1) for a short time by a thermal head or other means and rapidly cooled to fix the color. Further, if heating is performed for a short time (T2 <T1) using a hot stamp, a heating roll, or the like, the image is erased. Heating by thermal head is several milliseconds
Heating by hot stamping or the like is performed for a relatively long time of 0.1 to several seconds. The reversible thermosensitive recording material of the present invention can form a reversible image by controlling the heating temperature and the heating time.

[0023]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples.

(Example 1) Solution A Dye precursor: 3-ethylisobutylamino-6-methyl-7-anilinofluoran 30 parts by weight Binder: polymethyl methacrylate 6 Solvent: toluene 150 B Solution B: hydroxyphenylbenzoic acid: 4- (4-hydroxyphenyl) benzoic acid 25 parts by weight Organic amino compound: Stearylamine 38 Aliphatic phenone compound: Octadecanophenone 16 Binder: Polymethyl methacrylate 50 Solvent: Toluene 400 Solution A and Solution B are each paint shaker For about 4 hours, and then mixed well at a ratio of A liquid: B liquid = 1: 6 to prepare a coating liquid.

The coating liquid was coated on the surface of a white polyethylene terephthalate resin film having a thickness of 188 μm using a bar coater and dried to form a recording layer having a thickness of 7 μm. On top of this, an ultraviolet curable resin is cured to a thickness of 2μ.
m and cured with ultraviolet light to form a protective layer,
A reversible thermosensitive recording material of the present invention was produced.

(Example 2) Solution A Dye precursor: 30 parts by weight of 3-diethylamino-6-methyl-7-anilinofluoran Binder: vinyl chloride-vinyl acetate copolymer 10 Solvent: toluene 75 MIBK (methyl isobutyl ketone) Liquid 75B Hydroxyphenylbenzoic acids: 3- (4-hydroxyphenyl) benzoic acid 25 parts by weight Organic amino compound: hexadexylamine 28 Aliphatic phenone compound: Decanophenone 20 Binder: PVC-vinyl acetate copolymer 50 Solvent: Toluene 200 MIBK 200 A reversible thermosensitive recording material was produced in the same manner as in Example 1 except that the above composition was used.

(Example 3) Solution A Dye precursor: 30 parts by weight of 3-diethylamino-6-methyl-7-anilinofluoran Binder: polyvinyl alcohol 20 Solvent: water 250 B solution Hydroxyphenylbenzoic acids: 2- ( 4-hydroxyphenyl) benzoic acid 25 parts by weight Organic amino compound: Stearylamine 38 Aliphatic phenone compound: Decanophenone 10 Binder: Polyvinyl alcohol 20 Solvent: Water 250 Other than dispersing with a paint shaker using the above composition for 3 hours. A reversible thermosensitive recording material was produced in the same manner as in Example 1.

(Example 4) Liquid A Dye precursor: 30 parts by weight of 3-dibutylamino-6-methyl-7-anilinofluoran Binder: polymethyl methacrylate 10 Solvent: toluene 150 Liquid B Hydroxyphenylbenzoic acid: 4-hydroxyphenylbenzoic acid 25 parts by weight Organic amino compound: hexadecylamine 38 Aliphatic phenone compound: Decanophenone 4 Long-chain alkyl compound: Stearamide 10 Binder: Polymethyl methacrylate 50 Solvent: Toluene 300 A reversible thermosensitive recording material was prepared in the same manner as in Example 1 except for using the same.

(Comparative Example 1) Liquid A Dye precursor: 30 parts by weight of 3-methylisobutylamino-6-methyl-7-anilinofluoran Binder: polymethyl methacrylate 10 Solvent: toluene 150 Liquid B Phenolic compound: gallic acid 37 parts by weight Organic amino compound: laurylamine 40 Binder: polymethyl methacrylate 25 Solvent: toluene 300 A reversible thermosensitive recording material was prepared in the same manner as in Example 1 except that the above composition was used.

(Comparative Example 2) Solution A Dye precursor: 30 parts by weight of 3-diethylamino-6-methyl-7-xylidinofluoran Binder: polymethyl methacrylate 10 Solvent: toluene 150 Solution B Hydroxyphenylbenzoic acid: 2 -(4-hydroxybenzoyl) benzoic acid 30 parts by weight Organic amino compound: decylamine 20 Binder: polymethyl methacrylate 25 Solvent: toluene 200 Except for using the above composition, the reversible thermosensitive recording material was the same as in Example 1. Was prepared.

Comparative Example 3 Liquid A Dye precursor: 30 parts by weight of 3-diethylamino-6-methyl-7-anilinofluoran Binder: polymethylmethacrylate 10 Solvent: toluene 150 Liquid B Hydroxyphenylbenzoic acid: 3 -(4-hydroxyfinyl) benzoic acid 30 parts by weight Aliphatic phenone compound: hexadecanophenone 10 Binder: polymethyl methacrylate 25 Solvent: toluene 200 Reversible in the same manner as in Example 1 except that the above composition is used. A thermosensitive recording material was prepared.

(Rewrite test) The reflection density of the reversible thermosensitive recording material produced as described above was measured using a Macbeth reflection densitometer RD.
It measured by -914 and set it as the background density. Next, printing was performed using a thermal head (0.35 mJ / dot), and the reflection density of the printed portion was measured to obtain the printing density. The printed reversible thermosensitive recording material was heated with a hot printing plate at 110 ° C. for 2 seconds, and the reflection density of the reversible thermosensitive recording material was measured to obtain the erase density.
Table 1 shows the results.

[0033]

[Table 1] As is clear from Table 1, Examples 1-3, which are reversible thermosensitive recording materials containing hydroxyphenylbenzoic acid or a derivative thereof, an organic amino compound, and an aliphatic phenone compound, can be printed, The erasure density of the print is low and is almost the same as the background density. In particular, Example 4 containing a compound having a long-chain alkyl group having 12 or more carbon atoms
Indicates that the erase density and the background density are almost the same, and the print density is increased.

On the other hand, Comparative Example 1, which does not contain hydroxyphenylbenzoic acid or a derivative thereof and an aliphatic phenone compound, has a very low print density. Comparative Example 2 containing no aliphatic phenone compound has a high erase density.
Comparative Example 3 containing no organic amino compound has a very low print density.

The recording materials of Examples 1 to 4 were repeatedly evaluated for durability. Printing and erasing were repeated about 50 times, but there was no particular change in the printing density and erasing density. In Example 4, stearic acid as an aliphatic carboxylic acid, behenic acid amide as an aliphatic amide, cetyl alcohol as an alcohol, stearone as a ketone, and an aliphatic urea compound as long-chain alkyl compounds were used. Even when a certain n-stearyl urea was used, the same results as in Example 4 could be obtained.

[0036]

According to the reversible thermosensitive recording material of the present invention, the background density does not increase even after repeated use, and the erasing performance does not decrease.

Claims (2)

[Claims] 1. A reversible thermosensitive recording comprising a dye precursor which becomes a dye by emitting electrons on a support, and an electron-accepting compound, and forms an image by forming a color-developed state and a decolored state depending on heat treatment temperature conditions. The reversible thermosensitive recording material is characterized in that the reversible thermosensitive recording material contains hydroxyphenylbenzoic acid or a derivative thereof, an organic amino compound, and an aliphatic phenone compound. 2. The reversible thermosensitive recording material according to claim 1, further comprising a compound having a long-chain alkyl group having 12 or more carbon atoms.