JPS6145548B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing a negative copy of an original onto heat-sensitive copy sheet material by heat conduction from the selectively heated image areas of the original by briefly exposing the original to intense infrared radiation. The present invention relates to a material suitable for thermal copying in which a color is formed, or for thermal recording, in which areas selectively heated by a thermal head are discolored.

There are two types of thermal image forming materials that utilize discoloration due to heating to form an image: those that utilize sublimation of a colored substance and those that utilize a discoloration reaction between a p-quinone imine color body and a reducing agent when heated. .

The present invention utilizes a new reaction system different from conventional ones, such as in thermal copying or when selectively heated by a thermal head.
The present invention provides a heat-sensitive fading material whose image area changes from a colored state to a colorless state. The present invention utilizes the fact that merocyanine dye fades in a heated region by reacting with an oxidizing agent having an appropriately strong oxidizing action.

The heat-sensitive fading material of the present invention is colored with a merocyanine dye. The dye may be coated in a film-forming binder on paper, plastic film, or other support, or impregnated into the surface layer of the support. The oxidizing agent is contained in the same binder containing the dye, or in a layer adjacent to the layer containing the dye. The surface may further be coated with a topcoat layer. It is necessary to use an oxidizing agent having an appropriately strong oxidizing action.
If it is too strong, the coloring will fade before heating. If it is too weak, the coloring will not fade during heating.

Examples of merocyanine dyes useful in the heat-sensitive fading material of the present invention include the following.

The following compounds can be mentioned as oxidizing agents useful in the present invention.

Chloramines such as chloramine T and chloramine B, amine-N-oxides such as trimethylamine-N-oxide, pyridine-N-oxide, N-methylmorpholin-N-oxide, t-butyl hydroperoxide, cumyl peroxide Peroxides such as sodium periodate, periodates such as periodic acid, iodosobenzenes such as iodosobenzene, iodooxybenzene, iodosobenzene dichloride, and iodosobenzene diacetate.

As the binder, the following polymers can be mentioned.

Polyvinyl butyral, polyvinyl formal, polystyrene, styrene-acrylonitrile copolymer, styrene-acrylate copolymer, styrene-butadiene-acrylonitrile copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinylidene chloride-acrylonitrile copolymer, vinylidene chloride-vinyl acetate copolymer, polyvinyl chloride Methyl methacrylate.

The concentration of merocyanine dye must be sufficient to provide distinct coloration, but excess amounts are undesirable as more oxidizing agent is required.

The amount of oxidizing agent needs to be sufficient to fade the color upon heating, but need not be excessive.
The amount of the oxidizing agent varies depending on the type of oxidizing agent, the combination with the dye, and the type of binder, so it cannot be determined unconditionally, but a guideline is 2 to 10 weights per weight of the dye.

Next, the present invention will be further explained with reference to Examples, but the present invention is not limited thereto.
Note that merocyanine dyes are indicated by the numbers attached to the structural formulas described above.

Example 1 The compounds shown below are added in the following order with stirring to create a solution. This solution was applied onto a 50μ thick polyester film to a wet thickness of 100μ and dried at room temperature.

Methyl ethyl ketone 4g Methanol 1g Polyvinyl butyral 0.36g Dye 4 0.006g Chloramine T 0.028g Next, a 4% by weight solution of cellulose acetate butyrate in methyl ethyl ketone was applied as an overcoat layer to a thickness of 50μ when wet, and dried at room temperature. The resulting sheet is transparent and blue in color. This was superimposed on the original, which consisted of a drawing drawn in black ink on a blank sheet of paper, and passed through a thermographic copying machine. The blue color disappeared in the imagewise heated area. When this sheet is projected with an overhead projector,
A white image could be projected onto a blue background. Furthermore, when characters were written on the surface of this sheet with a hot pen at 110°C, colorless characters were formed on a blue background.

Example 2 A solution is prepared by adding the compounds shown below in the following order while stirring. This solution was applied onto a 50 μm thick polyester film in the same manner as in Example 1 and dried to produce a sheet colored bluish-purple.

Methyl ethyl ketone 4g Methanol 1g Polyvinyl butyral 0.36g Dye 9 0.006g Chloramine B 0.03g Furthermore, as an overcoat layer, a 4% by weight solution of cellulose acetate butyrate in methyl ethyl ketone,
It was applied to a wet thickness of 50μ and dried at room temperature.

A negative color projection transparent sheet was obtained by the thermographic copying method as described in Example 1. Also, as in Example 1, characters could be written with a thermal pen.

Example 3 A reddish-purple colored sheet was prepared using the same method as in Example 1 from the compounds shown below.

Methyl ethyl ketone 4 g Methanol 1 g Polyvinyl butyral 0.36 g Dye 6 0.006 g Chloramine T 0.056 g Overcoat 4% by weight solution of cellulose acetate butyrate in methyl ethyl ketone A negative color projection transparent sheet was obtained by thermographic copying method similar to that shown in Example 1. Ta.
Also, as in Example 1, characters could be written with a thermal pen.

Example 4 First solution Methyl ethyl ketone 4g Polyvinyl butyral 0.36g Dye 16 0.006g Second solution Acetone 4g Cellulose acetate 0.36g Chloramine T 0.08g The first solution having the composition shown above was spread on a 50μ thick polyester film at a thickness of 100μ when wet. It was applied to a thickness of 100 ml and dried at room temperature. The second solution was then applied over it to a wet thickness of 50μ and dried at room temperature. A purple colored sheet was obtained. A negative color projection transparency sheet was obtained by a thermographic copying process similar to that described in Example 1. Also, as in Example 1, characters could be written with a thermal pen.

Claims (1)

[Scope of Claims] 1. A heat-sensitive fading material comprising a film-forming binder, a merocyanine dye, and an oxidizing agent, which is characterized in that heated regions are discolored. 2. The heat-sensitive fading material according to claim 1, wherein the oxidizing agent is selected from chloramines, amine N-oxides, peroxides, periodates, and iodosobenzenes. 3. The heat-sensitive fading material according to claim 1, wherein the oxidizing agent and the dye are contained in the same binder. 4. The heat-sensitive fading material according to claim 1, wherein the oxidizing agent is contained in a separate layer adjacent to the dye-containing layer.