JPS5998896A - Recording medium - Google Patents

Abstract

PURPOSE:To form a recording medium capable of performing recording by near infrared rays such as semiconductor laser and having high sensitivity, high resolving power and excellent storage stability, by compounding a 3,3-di-substituted-2-oxo-2,3-dihydroindole derivative and a near infrared ray absorber. CONSTITUTION:A, 3,3-di-substituted-2-oxo-2,3-dihydroindole derivative shown by a formula I (wherein R1 and R2 are same or different and shows a heterocyclic group containing at least one nitrogen atom and R3 is a hydrogen atom or an alkyl group) and a near infrared absorber having absorption wavelength in a near infrared region of 0.8-2mum are compounded. Because the compound used as the color forming component shown by the formula I is present in a molecularly dispersed state, when recording is performed by near infrared rays, high sensitivity and high resolving power are obtained and the production of a recording medium is made extremely easy. In addition, because the color forming component comprises only one component, fog caused by the contact of color forming components is not generated and high storage stability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording medium that performs small recording by irradiation with near-infrared light without using direct heating means such as a thermal recording head.

The thermal recording method is a direct recording method that does not require development or fixing.
It is applied to printers and facsimiles because of its ease of operation and maintainability.

However, because the heat-generating recording head and heat-generating pen are brought into direct contact with the heat-sensitive recording paper for heating recording, there is a problem in that recording material residue and the like adhere to the recording head and pen, impairing recording quality. Furthermore, since the recording head moves while being in close contact with the recording material, a decrease in resolution due to wear of the recording head heating element cannot be avoided.

Furthermore, when performing thermal recording with a recording head, it is usually necessary to heat the recording head section to 400°C or higher, although it depends on the type of heat-sensitive material, and the power consumption required for recording is 1 to 5 yn:r.
/ It was very large.

This problem becomes more prominent as the recording head becomes denser and larger, and also due to thermal isolation between the heated dots on the recording head that are heated to high temperatures or when the recording dots move the recording material at high speed. Unless the thermal history is resolved, it will be difficult to reduce the total time required for A-4 size recording to less than one minute, and solving this problem will create other problems such as increasing the size of the power supply.

In order to solve the above-mentioned drawbacks, for example, all types of originals for recording and transfer are placed at the bottom of a thermosensitive recording material, and the coloring agent is thermosensitively colored by exposing it to light from a light source and generating heat from the light absorbed by the light absorption part of the original. A method was proposed to do this. However, in this recording method, the heat generated in the light absorption layer is diffused, causing blurring of the recorded image and poor resolution.

Furthermore, instead of using a light-absorbing layer, there has been an attempt to record by incorporating a dye that absorbs the wavelength of the light source into the entire color-forming layer. However, the dyes that have been used for this purpose are visible light absorbing dyes such as methylene blue and rhodamine B, which have the problem of being colored themselves and resulting in insufficient contrast after recording.

In addition, a recording medium called NCR type, which is made of a combination of a leuco dye and a color developer and contains a near-infrared absorber, is also being considered, but such recording media have the following problems. (1) Since the coloring component is dispersed and coated, there is a limit to the resolution, and it is difficult to achieve a resolution of 20 lines/fi or more.0 (2) Leuco dyes are generally coated using water as a medium. However, the near-infrared absorber is poorly soluble in water, and in order to exist in the same layer, it is necessary to make it into dispersed particles. This results in a decrease in resolution and color development efficiency.

(3) There has been an attempt to separate the leuco dye and color developer using multilayer plug coating, but the color develops quickly at the interface, and to prevent this, five or more layers are required, making it difficult to manufacture. , and a decrease in color development sensitivity occurs.

An object of the present invention is to provide a complete recording medium that can be recorded with near-infrared light such as a semiconductor laser and has high sensitivity, high resolution, and excellent storage stability without the drawbacks of the prior art.

That is, to summarize the present invention, the present invention is an invention of a recording medium, comprising the following general formula 1 (wherein R1 and R2 are the same or different and represent a heterocyclic group containing at least one nitrogen atom, R3 represents a hydrogen atom or an alkyl group)
2-oxo-2,5-dihydroindole derivative and α
It is characterized by containing a near-infrared absorber having an absorption wavelength in the near-infrared region of 8 to 2 μm.

Hereinafter, the recording medium of the present invention will be explained in detail. In the present invention, the 6,5-disubstituted-2
-Oxo-2,5-dihydroindoles are used as coloring components. These compounds remain as single components and change into deep blue pigments through condensation reactions or heating. [For details see A, J.

A report by Johnson et al., Journal of Chemical Science (J.

Chem, 5oc-) 1957, p. 5470. ] Therefore, there is no need to use a multi-component coloring material, and it is possible to coat uniformly using a solution system, and it is also possible to use a single-layer recording medium that contains a near-infrared absorber and a coloring component in the same layer. It can also be achieved. In these media, there are no particles like those found in dispersion systems, and the coloring components exist in a molecularly dispersed form, so it is necessary to take into account the diffusion of the coloring components during recording and the total particle size of the colored material after recording. do not have.

Therefore, when recording with near-infrared light, high sensitivity and high resolution can be obtained. Furthermore, since it is not necessary to separate the coloring components in the recording medium, the production of the recording medium is extremely easy. Furthermore, since the color-forming component is composed of only one component, fogging due to contact with the color-forming component does not occur, and high storage stability can be obtained.

As the base material of the recording medium of the present invention, a plastic sheet (Mylar film, etc.), a plastic plate (acrylic resin, polycarbonate, etc.), a glass plate, paper, etc. can be used.

Examples of compounds that have an extremely thick absorption wavelength in the near-infrared light region of α8 to 2.0 μm include cyanine dyes, such as NK116+ (95Q nm) manufactured by Japan Photosensitive Color Research Institute (Co., Ltd.).
, NK104 (794nm), NK1748 (
859nm), NK427 (805nm), etc. (The number in parentheses indicates the thickest absorption wavelength). Also, the near-infrared absorber FA-1001 (11
0'Onm), FA-1002 (895nm
), FA-1005 (880nm), FA-10
'05 (850nm), FA-1006
(870 nm) etc. (The number in parentheses indicates the absorption peak wavelength).

Next, we will explain the method for producing the recording medium of the present invention.0 As described above, the coloring material and the near-infrared absorber were dissolved in a binder material that transmits visible light, and the solution was applied onto the base material using a wire bar, spinner, etc. Dry later. When the base material 1 is not used, the dry film is peeled off from the base material. The coloring material and the near-infrared absorber can also be applied separately.

To perform recording using a medium with the above configuration, it is necessary to irradiate near-infrared light from a semiconductor laser, light-emitting diode, xenon lamp equipped with an ultraviolet absorption filter, etc. that matches the absorption wavelength of each near-infrared absorber. good.

EXAMPLES The present invention will be specifically explained below using Examples, but the present invention is not limited to these Examples.

Example 1 A solution (A)' having the following composition was prepared, applied onto high-quality paper using a wire bar, and then dried at 60°C. When this sample was irradiated with pulsed light from a semiconductor laser with a wavelength of 850 nm and an output of 10 mW, it was colored blue, and its optical density (Sakura densitometer, reflection mode, amber filter used) was [1.95]. In addition, when the sample was irradiated with photomask gold medal, a xenon lamp that cut out light with wavelengths shorter than 600 nm, a resolution of 50 lines/-Im was obtained.The base concentration of the sample was 25°C, RH 50%.
Even if I kept it for 5 months, it only increased from [125 to α28].

Example 2 A solution (B)'e having the following composition was prepared, spin-coded onto a glass plate, and then dried at 6oC. This sample has wavelength 8
When irradiated with pulsed light from a semiconductor laser with a wavelength of 50 nm and an output of 10 mW, it was colored blue and its optical density (Sakura densitometer, transmission mode, amber filter used was α8).
It was 5. Also, superimpose a photomask on the sample and
When light was irradiated with a xenon lamp that cut out light with wavelengths as short as nm, a resolution of 50 lines/pharynge was obtained.

The base concentration of the sample only increased from 0.25 to α5o even if it was kept at 25° C. and RH5Q% for 5 months.

Example 5 A solution CC3)k having the following composition was prepared, coated on high-quality paper using a wire bar, and then dried at 60°C.

A solution (I') having the following composition was applied to this using a full wire bar and dried again at 60°C. This sample has a wavelength of 850
When irradiated with pulsed light from a semiconductor laser with an output of 10 mW, it was colored blue and its optical density was 0.92.
Met. After that, a photomask was placed on the sample and 600n
When light was irradiated with a xenon lamp that canted light with a short wavelength of m, a resolution of 50 lines/wm or more was obtained.

Even if the base concentration of the sample was kept at 25° C. and R)I50 for 5 months, it only increased from 1.18 to 0.20.

Example 4 A solution (F) with the following composition was prepared, spin-coded onto a glass plate, and dried at 60°C.A solution (F) with the following composition was spin-coded on this and dried again at 60°C. . When this sample was irradiated with pulsed light from a semiconductor laser with a wavelength of 850 nm and an output of 10 mW, it was colored blue.
Its optical density was 1.02. In addition, when a photomask was placed on the sample and irradiated with a xenon lamp that cut off light with a wavelength as short as 600 nm, the base density of the sample 0, which obtained a resolution of 50 lines/gourd or more, was at 25°C and RH.
Even after keeping it at 5Q% for 5 months, it did not change from Q18.

Claims (1)

[Claims] 1. The following general formula I 3 (wherein R1 and R2 are the same or different, a heterocyclic group containing at least one nitrogen atom, and R3 is a hydrogen atom or an alkyl group) 5-di-substituted-
2-oxo-2,5-dihydroindole derivative and α
A recording medium characterized by containing a near-infrared absorber having an absorption wavelength in the near-infrared region of 8 to 2 μm.