JPH05124332A - Electron-receptive color developer and thermal recording material - Google Patents

Abstract

PURPOSE:To develop a new type of electron-receptive color developer and thereby obtain a thermal recording material with outstanding image preservation stability and rapid recording properties by composing an electron-receptive color developer using a fatty acid having an oxo group in the main chain, and using a color development reaction between the electron-receptive color developer and a coloring agent to constitute a thermal recording material. CONSTITUTION:An electron-receptive color developer is composed using fatty acid having an oxo group in the main chain (e.g. 3-oxooctanic acid). Further, a thermal recordind material is constituted using a color development reaction between the electron-receptive color developer and an electron-donative coloring agent (e.g. crystal violet lactone). This color developer of new type is used as a solution-type coating liquid when the thermal recording material is prepared with the electron-donative color developer. The thermal recording material obtained demonstrates high image preservation stability and rapid recording properties. In addition, it is easy to prepare a transparent recording material so that the material used for recording by an OA equipment with a thermal head mounted can be used as an OHP recording material.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electron-accepting color developer and a heat-sensitive recording material.

[0002]

2. Description of the Related Art Electron-donating color formers (hereinafter,
A heat-sensitive recording material utilizing a color-forming reaction between a color-developing agent) and an electron-accepting color-developing agent (hereinafter also simply referred to as color-developing agent) is known. In such a recording material,
In recent years, along with the development of society, there has been an increasing demand for high speed recording and high density recording. For this reason, it is strongly desired to develop a recording material capable of coping with the speeding up of the recording apparatus itself. From this point of view, Japanese Patent Laid-Open No. 53-
39139, JP-A-53-26139, JP-A-53
No. 5636, JP-A No. 53-11036, etc., further, various waxes, fatty acid amides, alkylated biphenyls, substituted biphenyl alkanes, in addition to the above-mentioned thermosensitive coloring layers,
It has been proposed to add a low-melting heat-melting substance such as coumarins and diphenylamines as a sensitizer (or melting point depressant). However, in the method of adding a sensitizer, it is necessary to melt the sensitizer before the color development reaction, so sufficient thermal response can be obtained in high-speed recording where only a small amount of heat is supplied by a short pulse. In addition to the above, the sensitizer in the color forming layer is melted, so that problems such as sticking of dust to the thermal head and bleeding of the color image, tailing, ghost, and the like are likely to occur. Further, when stored at high temperature and / or high humidity, fogging occurs over time and the contrast of a color image is often lowered. Therefore, it is desirable that the thermal recording sheet for high-speed recording has a structure in which no sensitizer is added.
However, since the colorless or light-colored color former used in the heat-sensitive recording sheet is usually as high as 160 to 240 ° C., it is necessary to add a low-sensitivity color-developing layer suitable for high-speed recording without adding a sensitizer. It is indispensable to use a developer having a melting point and a large ability to develop the color.

[0003] By the way, many color developing agents, especially phenolic compounds, which are used in combination with colorless or light color developing agent dyes are described in various documents including Japanese Patent Publication No. 14039/45, and bisphenol A is among them. It is widely used because of its stable quality, low price, and easy availability. However, this bisphenol A has a melting point of 156-1.
Since it is as high as 58 ° C., it has a drawback of low thermal sensitivity (and therefore high thermal color development temperature). On the other hand, a phenolic compound having a low melting point, for example, 4-t-butylphenol (melting point 94 to 99 ° C), α-naphthol (melting point 95 to 96).
C.), .beta.-naphthol (melting point 119 to 122.degree. C.) and the like are used, the thermal recording sheet is inferior in storage stability, and not only fogging gradually occurs even at room temperature, but a so-called phenol odor is strong. Not practical. Further, JP-B No. 54-12819 discloses 2,2-bis (4'-hydroxyphenyl) normal hexane (melting point: 99-103 ° C), and JP-A No. 55-27253 discloses 1,1-bis (4). It is described that a heat-sensitive recording sheet having high heat sensitivity, good storage stability and good color development can be produced by using each of'-hydroxyphenyl) alkane (alkane having 3 to 13 carbon atoms). All the substances are difficult to synthesize and have problems in availability. Further, JP-A-56-144193 describes that a high-sensitivity heat-sensitive recording sheet can be prepared by using a lower alkyl ester of p-hydroxybenzoic acid or benzyl.
This product has a storage defect that the color-developed portion is easily erased with time and crystals of the phenolic compound are precipitated (so-called white powder phenomenon). As mentioned above,
The color developer applied to the conventional thermal recording sheet for high speed recording has merits and demerits, and it has not yet been practically satisfactory.

[0004]

DISCLOSURE OF THE INVENTION The present invention has excellent reaction stability, does not show a color-forming reaction even when it is brought into contact with a color-forming agent in a solvent, and when it is reacted with the color-forming agent by heating, it is clear and has weather resistance. The present invention provides a new type of color developer which produces a color developing material having excellent properties and further provides a heat-sensitive recording material having excellent high-speed recording property and storage stability, and color formation between the color developing agent and the color developing agent. It is an object of the present invention to provide a heat-sensitive recording material utilizing a reaction.

[0005]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, fatty acids containing an oxo group in the main chain were superior to electron-donating color formers. The present invention has been completed by discovering that the compound has a color developing ability and found that the above problems can be solved by using such a compound as a color developing agent.

That is, according to the present invention, there is provided an electron-accepting color developer comprising a fatty acid having an oxo group in the main chain.
Further, according to the present invention, there is provided a heat-sensitive recording material utilizing the color-forming reaction between the electron-accepting color developing agent and the electron-donating color developing agent. Among the fatty acid derivatives having the oxo group,
Those containing a higher alkyl group having 12 or more carbon atoms give a reversible thermosensitive recording material when combined with a selected leuco dye. Such a reversible thermosensitive recording material can decolor the color former formed by the heating reaction by heating at a lower temperature.

Specific examples of the electron-accepting color developing agent of the present invention are shown below. 3-oxooctanoic acid, 4-oxooctanoic acid, 2-oxononanoic acid, 4-oxononanoic acid, 2-oxodecanoic acid, 3-oxodecanoic acid, 2-oxoundecanoic acid, 3
-Oxoundecanoic acid, 3-oxotetradecanoic acid, 4
-Oxotetradecanoic acid, 2-oxopentadecanoic acid,
3-oxopentadecanoic acid, 2-oxohexadecanoic acid, 3-oxohexadecanoic acid, 2-oxooctadecanoic acid, 3-oxooctadecanoic acid, 4-oxooctadecanoic acid, 4-oxodocosanoic acid, 3-oxobutanedioic acid, 2-oxo Pentanedioic acid, 3-oxopentanedioic acid, 2-oxohexanedioic acid, 3-oxohexanedioic acid, 2-oxoheptanedioic acid, 4-oxoheptanedioic acid, (1-oxobutyl) propanedioic acid, 5- Oxononanedioic acid, 2,4-dioxopentanoic acid, 3,5-dioxohexanoic acid, 4,6-dioxoheptanoic acid, 2,5
-Dioxohexanedioic acid, 3,4-dioxohexanedioic acid, 2,4-dioxoheptanedioic acid, 2,6-dioxoheptanedioic acid and the like.

On the other hand, as the electron-donating color former used together with such a developer, all substances known in the technical field such as pressure-sensitive recording and heat-sensitive recording can be used.
For example, crystal violet lactone, 3,3-bis (P-dimethylaminophenyl) phthalide, 3,3-
Bis (P-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (P-dibutylaminophenyl) phthalide, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-methylfluor Oran, 3-diethylamino-5,7-benzfluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylaminofluorane, 3-N, N-diethylamino-6-methyl-7-anilinofluorane, 3-
(N, N-diethylamino) -5-methyl-7- (N,
N-dibenzylamino) fluorane, benzoylleucomethylene blue, 3- (2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-
Methylphenyl) phthalide, 3-morpholino-7- (0
-Trifluoromethyl) anilinofluorane, 3-pyrrolidino-7- (0-trichloromethyl) anilinofluorane, 3- (Nn-butyl-Nn-propyl) amino-7- (m-acetyl ) Anilino Fluoran, 3-
(N, N-di-n-butyl) amino-7- (P-acetyl) anilinofluorane, 3-octylamino-7-
(2,4-dinitro) anilinofluorane, 3- (N-
Benzyl-N-cyclohexyl) amino-6-methyl-
7-anilinofluorane and the like can be mentioned.

The thermosensitive green material of the present invention is made of paper, synthetic paper,
It is produced by providing a thermosensitive color-developing layer containing the developer and the color-developing agent of the present invention on a support such as a plastic sheet or film. The heat-sensitive color forming layer preferably contains a binder in order to strongly bind it to the support.
Examples of such a binder include acrylic resin, terpene resin, vinyl acetate resin, styrene resin, polyester resin, ethylene-vinyl acetate copolymer, polyvinyl alcohol, celluloses, starch, casein, gelatin, wax and others. A conventionally known organic solvent or a binder soluble in water can be used.

The color developer is preferably contained in the same layer as the color developer from the viewpoint of production, but may be contained in separate layers.
The color former and the developer are mixed together with the binder,
When the mixed solution is applied on a support to form a color-developing layer, it is necessary to mix and dry the mixture within a temperature range that does not cause color development.

Since the developer of the present invention has excellent reaction stability, it does not develop color even when dissolved in an organic solvent together with the color former. Therefore, the coating liquid containing the color developer and the color developing agent of the present invention has an advantage that it can be used as a solution type coating liquid. Further, when the color developer of the present invention is used, it is easy to adjust the melting point temperature to a temperature in the range of 70 to 120 ° C. suitable for high speed recording. In the developer of the present invention, the melting point can be adjusted by changing the molecular weight or the kind of the substituent, or by combining two or more kinds. The image recorded on the color forming layer according to the present invention is clear, has excellent weather resistance, and has good long-term storage stability.

[0012]

EXAMPLES Next, the present invention will be described in more detail by way of examples. In addition, all parts and% shown below are based on weight.

Example 1 The following composition was dissolved to prepare a thermosensitive color forming layer forming liquid. 3- (N, N-di-n-butyl) amino-6-methyl 2 parts -7-anilinofluorane 2-oxohexadecanoic acid (mp 98 ° C) 6 parts Vinyl chloride-vinyl acetate copolymer (trade name VYHH , 20 parts, manufactured by Union Carbide Co., Ltd.) Solvent (tetrahydrofuran / toluene: 8/2 wt) 100 parts This solution is coated on a 100 μm-thick polyester film with a wire bar to a film thickness of about 15 μm, dried and heat-sensitive. A recording transparent film was prepared. Next, newspaper articles were copied to the thus obtained thermal recording material using CUVAX-MC50 (a thermal copying machine manufactured by Ricoh Co., Ltd.). A clear black image was obtained on the transparent film. When the image density of the solid portion was measured with a Macbeth densitometer RD-914, it was 1.23. This copied film was viewed on an OHP (overhead projector) as a clear projected image.

Example 2 The fluoran compound of Example 1 was converted into 3-cyclohexyl-6
-Chlorofluorane, 5-oxohexadecanoic acid 5
A thermosensitive recording material was prepared in the same manner as in Example 1 except that -oxononanedioic acid (mp 109 to 111 ° C) was used instead. Next, the obtained film was used as a recording paper of a word processor (My Report NL-3Ai manufactured by Ricoh Co., Ltd.) to perform printing, and a yellow-orange character image was obtained. This was visually recognized as a clear projection image on OHP.

Example 3 The following composition was dissolved to prepare a thermosensitive color forming layer forming liquid. 3,6-Di (N, N-diethylamino) fluoractamide 1.8 parts-(N-o-chlorophenyl) 4-oxodocosanoic acid (mp103 ° C) 5 parts Polyvinyl butyral (trade name, S-lex BX-1, 15 parts) Sekisui Chemical Co., Ltd.) Solvent (tetrahydrofuran / methyl ethyl ketone: 1/1 wt) 150 parts This solution is applied to a 100 μm-thick polyester film with a wire bar and dried at 55 ° C. or lower repeatedly to obtain about 15 μm.
The double color-developing layer was constituted so as to be m. The thermosensitive recording material thus obtained was subjected to CUV in the same manner as in Example 1.
Newspaper articles were copied with an AX-MC50 thermal copying machine.
A copy was obtained as a clear pink-red image on the transparent film. It was possible to see as a clear projection image of the same color on the OHP.

EXAMPLE 4 3- (N, N-diethyl) amino-5-methyl-6- (N, N-di-benzyl) aminofluorane was used in place of the electron-donating color former of Example 3, A thermosensitive recording material was prepared in the same manner as in Example 3 except that 3-oxopentadecanoic acid (mp 92 to 93 ° C.) was used as the electron-accepting developer. Next, using the film obtained here in place of the recording paper to print out the word processor,
A clear green character image was obtained. This is OHP
I was able to see it as a clear projected image of the same color.

Example 5 The following mixtures were milled in a glass ball mill for 30 hours to prepare the following liquids A, B and C. [Liquid A] 3-di- (N-ethyl-N-i-amyl) amino-6-20 parts Methyl-7-anilinofluorane 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Liquid B] 3- Oxooctadecanoic acid (mp 102 to 103 ° C.) 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts [C liquid] silica (Mizukasil P-527 manufactured by Mizusawa Chemical Co., Ltd.) 20 parts 5% aqueous solution of methyl cellulose 20 parts water 60 parts Next, [solution A] 10 parts, [solution B] 30 parts, [solution C] 30
Parts and 20% of isobutylene / maleic anhydride copolymer
A thermosensitive coloring layer forming liquid was prepared by mixing 30 parts of an alkaline aqueous solution. This was applied to a high-quality paper having a basis weight of 50 g / m ^{2 in} an amount of about 0.
A thermosensitive coloring layer was provided by coating and drying so that the coating amount was 5 g / m ^2, and the surface of the layer was calendered so that the surface smoothness was 500 to 600 seconds to prepare a thermosensitive recording material. Regarding the thermal recording paper obtained as described above, RIF
When a received image was obtained as a recording sheet of AX-V600 (GIII FAX machine manufactured by Ricoh Co., Ltd.), a clear black image comparable to a commercially available recording sheet was obtained.

[0018]

The color developer of the present invention is of a new type that has not been known so far, and is used as a solution type coating solution when it is combined with an electron donative color developing agent to form a thermosensitive color developing layer. It has the feature that it can. Further, since a transparent type recording material is easily produced, the recording material recorded by an OA device equipped with a thermal head can be used as an OHP recording material. In addition, since it can be used for the preparation of conventional thermal recording paper to obtain a recording material that is comparable, it is highly practical.

Claims (2)

[Claims] 1. An electron-accepting color developer comprising a fatty acid having an oxo group in the main chain. 2. A heat-sensitive recording material utilizing the color-forming reaction between the electron-accepting color developing agent and the electron-donating color-developing agent according to claim 1.