JPS63173684A - Reversible recording material - Google Patents

Abstract

PURPOSE:To enable a fixing in a color-forming state, by a method wherein a recording layer containing a fluorane leuco dye shown by a specific general formula and an ascorbic acid 6-0-acyl derivative is formed on a substrate. CONSTITUTION:A coating liquid is prepared by dissolving or dispersing a mixed material of a fluorane leuco dye shown by formula I (R1, R2 represent respectively hydrogen, a 3-18 C alkyl, aralkyl, aryl, substd. aryl, and cycloalkyl, and R3 represents alkyl, halogen, alkyl aralkyl, and aryl-substd. amino), an ascorbic acid-6-0-acyl derivative, and a binder in a solvent such as an acetone. This coating liquid is applied on a substrate, such as a paper, plastic, and synthetic paper, and dried; in this manner, a reversible recording material is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a repeatedly usable recording material used as a heat-sensitive recording material, a reversible recording material, a display, and the like.

Color-forming materials that develop color when heated and disappear at room temperature, or vice versa, are known as thermochromic materials, and are useful as reusable recording materials, temperature-indicating materials, or display materials. Use is proposed.

Conventional reversible thermosensitive coloring materials utilize the principle of color change due to pH change, crystal transition, dehydration, solid phase change, or electron transfer between an electron donor and acceptor, but the biggest drawback of all of them is that temperature changes The color density changed as a function of time and the color turned off, making it impossible to fix the color in the developed state. In order to maintain the colored state, that is, the color density, continuous heat supply was required.

JP-A-60-101171 describes a heat-sensitive composition using a heat-sensitive dye and ascorbic acid or a derivative thereof as a color developer, and a fluoran compound is shown as an example of the heat-sensitive dye. There is. However, the combination of the specific fluoran dye of the present invention and an ascorbic acid derivative is not disclosed, and there is no suggestion of the effect of reversibly developing and decoloring and being able to fix the colored state. It has not been.

Also, JP-A-61-237684 and JP-A-61-237684
Publication No. 239444 discloses a thermochromink organic material that uses a leuco dye and an organic solid acid to reversibly exist a highly colored state and a less colored state at room temperature, but the specific material of the present invention Nothing is shown about it.

The present invention is characterized in that the coloring state and decoloring state reversibly change by heating with a thermal head or laser light irradiation,
Moreover, it is an object of the present invention to provide a reversible recording material that can be fixed in a colored state.

M missing bridge disappears.

The reversible recording material of the present invention is characterized by containing a leuco dye represented by the following general formula (I) and an ascorbic acid-6-0-acyl derivative as main components.

(In the formula, the symbols indicate the following.

R, R2: hydrogen, C, 1, represents a substituent such as an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group, a substituted aryl group, and R1 and R2 can become an alkylene group to form a ring. .

R1: alkyl group, halogen, alkyl ruaralkyl group or aryl substituted amino group) The present invention will be explained in more detail below.

In the present invention, a specific fluoran compound represented by the above general formula (I) is used as the leuco dye, and specific examples thereof include the following. These may be used alone or in combination of two or more.

(I) 3-N, N-dipropylamino-7-lyrofluorane"-1・0°\, (blank below) (2) 3-N, N-n-propyl-n-butylamino-7-t -Butylfluorane°-1”0゛＼, (3) 3-N-butylamino-7-N,N-methylphenylfluorane (blank below) (4) 3-octylamino-7-anilitous fluorane ( 5) 3-N-hexadecano-7-methylaminofluorane (6) 3-pyrrolidino-7-dibenzylaminofluorane (7) 3-N, N-n-butyltolylamino-7-N
, N-methylphenylfluorane (8) 3- N , N -n-dibutylamino-7
-〇-riloranilinofluorane n-H,C,\ (9) 3-N, N-n-dibutylamino-7-P-acetylanilinofluorane n-H,C,\ ) (I0) 3-pyrrolidino-7-o-toluidinofluorane (I1) 3-N,N-cyclohexyl n-butylamino-7-p-acetylanilinofluorane (hereinafter referred to as the margin) (I2) 3- Octylamino-7-(2,4-dinitroanilino)fluoran (I3) 3-N, N-n-butyl-n-propyl 7-m-acetylanilinofluorane n-H,C4\ Used as a color developer As the ascorbic acid-6-0-acyl derivative, one represented by the following general formula (II) is used.

(R, Niacyl Group) Specific examples of this ascorbic acid derivative include the following, which may be used alone or b) may be used in combination of two or more.

(I) L-ascorbic acid-6-0-butyryl (2) L
-Ascorbic acid-6-0-lauryl (3) L-ascorbic acid-6-0-valmityl (4) L-ascorbic acid-6-0-myristyl (5) L-ascorbic acid-6-〇-stearyl (hereinafter Margin) The reversible recording material of the present invention can be obtained by forming a recording layer containing the leuco dye and an ascorbic acid-6-0-acyl derivative on a suitable support, and usually
A binder is used. The binder is appropriately selected depending on the purpose of use, whether it is used dissolved in a solvent or used as an aqueous dispersion. Specific examples of such binders include starch, methyl or ethyl cellulose and its derivatives, polyvinyl alcohol, vinyl chloride-vinyl acetate copolymer, vinyl acetate-maleic acid copolymer, polyvinyl butyral, polyester, resins such as silicone resins, etc. These can be used alone or in combination of two or more.

When the binder is dissolved in a solvent, vinyl chloride-vinyl acetate copolymer is suitable, and when the binder is used in an aqueous dispersion system, polyvinyl alcohol is suitable.

The recording layer also contains calcium carbonate.

Modifiers such as titanium oxide and silica may also be added.

To produce the reversible recording material of the present invention, a leuco dye, an ascorbic acid-6-0-acyl derivative, a binder, and optionally a modifier are added to a support such as paper, plastic, or synthetic paper. Prepare a paint that is dissolved or dispersed in a solvent such as methyl alcohol, acetone, or tetrahydrofuran, or a paint that is made into a dispersion using water.
A recording layer can be formed by applying this paint onto a support and drying it.

The amount of each component to be used is 0.5 to 4.0 parts by weight, preferably 2.1 to 3.7 parts by weight of the ascorbic acid-6-0-acyl derivative per 1 part by weight of the leuco dye; 1.0 to 3.0 parts by weight, preferably 1.5 to 2.0 parts by weight are suitable.

The amount of the recording layer deposited is suitably 0.5 to 5 glrd, preferably 1.5 to 3.5 g/-.

The reversible recording material of the present invention can be heated to a high temperature, e.g.
It is possible to develop a color by heating it to 35° C., and maintain the color development state even if it is cooled to room temperature in this state. Further, when heated again to a low temperature, for example, 65 to 90° C., the recording layer is decolored, and even when the temperature is returned to room temperature, the decolored state is maintained and fixing is possible. Therefore, by using the reversible recording material of the present invention, it is possible to realize a reversible recording process that can be used repeatedly, in which information is recorded by heating to a high temperature and the color is erased by heating to a low temperature.

According to the present invention, a specific leuco dye and ascorbic acid
By using a 6-0-acyl derivative, coloring and decoloring change reversibly depending on the temperature by heating with a thermal head or the like.

Furthermore, it is possible to realize a recording material in which the color development state can be fixed and which can be used repeatedly.

Example 1 1 part by weight of 3-N,N-dibutyl-7-chlorofluorane, 2.3 parts by weight of 6-〇-lauryl ascorbic acid, and 3.5 parts by weight of vinyl acetate-vinyl chloride copolymer. was dissolved in 30 parts by weight of tetrahydrofuran, applied onto a polyester film with a thickness of 25 μI using a wire bar, and dried to obtain a white reversible recording sheet having a recording layer of 2.5 g/rrl'. .

Next, this recording sheet is heated to 1°C using a thermal head.
When printed at 05°C, a clear reddish image was obtained. When the reflection density was measured using a Macbeth densitometer, it was 0.
．． The image density was 52. Next, change this image to 70~
When heated for 10 seconds in a dryer adjusted to 90°C, most of the color had disappeared. The density after this decolorization is 0.23
Met.

Furthermore, the same procedure as above was applied to the recording sheet after decoloring.
When printing was performed at ℃, a clear reddish image was again formed. Furthermore, when this was heated again in a dryer at 70 to 90°C for 10 seconds, most of the color had disappeared. In this way, color is developed at high temperature (I05℃) and at low temperature (70-90℃).
A reversible, temperature-dependent, color-developing type recording sheet that can be decolored at 50°C (°C) was obtained.

Example 2 1 part by weight of 3-N,N-n-dibutylamino-7-orthochloroanilinofluorane, ascorbic acid-6-0-
Myristail 3.0 parts by weight, polyvinyl alcohol 10
% aqueous solution and 12 parts by weight of water were dispersed in a ball mill for 48 hours, coated on a 25 μm thick polyester film using a wire bar, and dried at 70° C. to form a 12 μm reversible recording layer. A white recording sheet was obtained.

Next, printing was performed at 110° C. according to Example 1, and a clear black image was obtained with a single image density of 0.76.

Furthermore, by reheating at 70 to 90°C, most of the colored images were erased, and the density after erasing was 0.28. By repeating the process, these images were reheated on the high temperature side (as in Example 1). Color develops at I10℃), and at low temperatures (70-90℃).
A reversible, temperature-dependent coloring and fading type recording sheet was obtained, which could be decolored at a temperature of 10°C.

Example 3 1 part by weight of 3-hexadecanoamino-7-methylaminofluorane, 3.3 parts of a 1:1 mixture of 6-0-palmityl ascorbate and 6-〇-stearyl ascorbate.
20 parts by weight of a 10% solution of polyvinyl alcohol and 10 parts of water were dispersed in a ball mill for 948 hours, coated on a 25 μm thick polyester film using a wire bar, and dried at 50°C to give a total of 2.3 g/ An uncolored recording sheet having a reversible recording layer of m was obtained.

Next, printing was performed at 95° C. according to Example 1, and a clear green-black image was obtained. The image density was 0.68. By further heating to 70° C., the image was decolored, and the decolorized density was 0.24.

As described above, by repeating these recording-erasing processes, a reversible temperature-dependent type of color fading can be achieved by heating to a high temperature of 90 to 95°C and decoloring to a low temperature (70 to 80°C). A color recording sheet was obtained.

Example 4 1 part by weight of 3-pyrrolidino-7-dibenzylaminofluorane, 3.0 parts by weight of ascorbic acid-6-0-stearyl, and 3.5 parts by weight of vinyl acetate-vinyl chloride copolymer were added to 30 parts by weight of tetrahydrofuran. This was applied onto a 25 μm thick polyester film using a wire bar and dried at 105° C. for 15 seconds to obtain a slightly dark green recording sheet.

When this recording sheet was irradiated with a He-Ne laser having a wavelength of 633 nm and a beam diameter of 10 μm, a greenish-black color change was observed in the irradiated area.

Then, this recording sheet was heated for 10 seconds in a dryer set at 75° C., and the green-black discoloration disappeared to a pale dark green.

A recording sheet was obtained that can reversibly repeat color development by laser light irradiation and decolorization at lower temperatures.

Claims (1)

[Scope of Claims] 1. A reversible recording material characterized by containing as main components a fluoran leuco dye represented by the following general formula (I) and an ascorbic acid-6-O-acyl derivative. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, the symbols indicate the following. R_1, R_2: Hydrogen, C_3_ to_1_8 alkyl group, cycloalkyl group, aralkyl group, aryl group , represents a substituent such as a substituted aryl group, and R_1 and R_2 can become an alkylene group to form a ring. R_3: represents a substituent such as an alkyl group, halogen, alkylaralkyl group, or aryl-substituted amino group.)