JPS58124690A - Multicolor thermal recording material - Google Patents

Abstract

PURPOSE:To provide a recording material free from texture halation or the like which is excellent in the separation of color by providing a multilayer thermal coloring layer comprising a lower layer employing an organic metal compound as developing agent and an upper layer employing organic acid and a phenol compound as developing agent on a supporting body. CONSTITUTION:A heat-sensitive coloring layer forming liquid made up of a colorless or light color leuco dye, an organic metal compound, a binder and the like is applied and dried on a supporting body to form a first heat-sensitive coloring layer. Then, a heat-sensitive coloring layer forming liquid comprising a leuco dye capable of developing color in the tone different from said leuco dye, organic acid (e.g. maleic acid) or phenol-affiliated compound (e.g. alpha-naphthol) and a binder is applied and dried on the first layer to form a second heat sensitive coloring layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multicolor heat-sensitive recording material [11L, specifically a multicolor heat-sensitive material in which a plurality of heat-sensitive coloring layers that develop different colors at different heating temperatures are laminated.

The thermosensitive recording material is a material in which a thermosensitive coloring layer that forms a coloring surface g1 by heating is provided on a support such as paper, and
Thermal printers equipped with thermal heads are widely used for heating. These conventional heat-sensitive recording materials and 1. Here, a colorless or light-colored leuco dye (color-forming agent) having a lactone ring, lactam ring, spiropyran ring, etc. in the heat-sensitive color-forming layer, and a color developer (color-forming aid) that reacts with this leuco dye to form color when heated. The color tone is clear and there is little fogging phenomenon, so it is widely used.

By the way, heat-sensitive recording materials can easily produce colored images just by heating them, so they are not only used for copying drawings, documents, etc., but also for recording the output of measuring devices in various information pots such as electronic computers, facsimiles, and telex machines. However, depending on the purpose of recording, in order to clearly display necessary data or numbers, the color of that part (display color) is different from the color of other parts. It goes without saying that it is desirable to be able to record.

In order to meet these demands, much research and development is being carried out everywhere, and several multicolor thermosensitive recording materials have been proposed. When I tried the color heat-sensitive recording material again,
There are problems with color separation such as color mixing and bleeding, and there are still problems such as background fogging during storage, liquid blurring, and head matching due to energy control of the heating element. It became clear that

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a multicolor heat-sensitive recording material that solves the above-mentioned problem and makes it possible to obtain both high-quality multicolor recording materials.

Another object of the present invention is to provide a multicolor heat-sensitive recording material that can be produced without employing particularly complicated manufacturing means.

That is, the present invention provides a polychromatic thermosensitive material in which a plurality of heat-sensitive color-forming layers each consisting mainly of a colorless or light-colored leuco dye and a color developer that develops color by reacting with the leuco dye upon heating are laminated on a support. The recording material 2 is characterized in that the color developer in the lower heat-sensitive color forming layer is an organic metal compound, and the color developer in the upper heat-sensitive color forming layer is an organic acid or a phenolic compound.

The recording material of the present invention will be explained in more detail below. This multicolor thermosensitive recording material basically has a multilayer thermosensitive coloring layer provided on a support (paper, synthetic paper, resin film, etc.). However, if necessary, the main coloring agent, coloring auxiliary agent, etc. of the heat-sensitive coloring layer that is originally in contact with the support are soaked into the support or added to the support as a self-supporting layer. One thermosensitive coloring layer to be formed on top can be omitted.

In the present invention, the multi-J-shaped thermosensitive coloring layer on the support is laminated in the order according to the heat-sensitive temperature. A compound is used as a coloring aid, and an organic acid or a phenolic compound is used as a coloring aid in the upper layer (thermosensitive coloring layer near the surface of the heat-sensitive recording material) to intentionally create a difference in heat-sensitive temperature between layers. Care has been taken to ensure that each color develops a different color.

The main color forming agent (color forming substance) used in the present invention is as follows:
These are leuco compounds such as triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran. Typical examples of these are 3, s-bis(p-dimethylaminophenyl)-6-dimethylamino 7-thallide s, s. -gs(p-dimethylaminophenyl)7talito3.3-bis(p-dimethylabanophenyl)-6-dinithylabanophthalide3.3-bis(p-dimethylabanophenyl)-6-chlorophthalide3-(N -p-tolyl-N-ethylamino)-6-methyl-7-(N-phenylamino))fluoran 3-diethyl-ino-7-chlorofluoran pensoyl leucomethylene blue 6'-chloro-8'-methoxy-benzoin Examples include dolino-bilirosvirane 2-(s,a-bis(jetylua))-9-(o-chloroanilino)xanthyl]benzoic acid lactam.

As the main coloring agent, it is preferable to use leuco dyes that develop colors such as blue, red, and green for the heat-sensitive color-forming layer (upper heat-sensitive color-forming layer) on the surface; The main coloring agent in the upper thermosensitive coloring layer) may be a leuco dye that can produce a colorless color or a color close to black when combined with the leuco dye of the upper thermosensitive coloring layer, or a color tone different from that of the upper thermosensitive coloring layer. Any leuco dye that can develop color can be used.

It is also effective to provide an intermediate layer containing a decoloring agent between the heat-sensitive coloring layer and other heat-sensitive coloring layers. When such an intermediate layer is provided, it is appropriate to use leuco dyes that are complementary colors to each other as the leuco dyes added to each thermosensitive coloring layer.

Among the coloring aids used in the present invention, organometallic compounds are used in the lower heat-sensitive coloring layer.

Examples of such single metal compounds include the following. All of these compounds are known substances and can be easily obtained as commercially available products or by synthesis.

Further, the coloring aid used in the upper heat-sensitive coloring layer is a phenolic compound or an organic acid.

The phenolic compounds here include α-7thol, β-naphthol, 4-1・rt-butylphenol,
4-tart-octylphenol, 4-phenylphenol, 2,2'-bis(p-hydroxyphenyl)
Propane, 2. r-1s (p-1=droxyphenyl)
Butane, 4,4'-cyclohexylidene diphenol,
2.1-bis(2,5-di-i-lo-5-4-hydroxy-7enyl)propane, 4,4'-isopropylidene bis(
Examples include 2-t@rt-butylphenol) and 2,2'-methine/bis(4-chlorophenol).

Examples of organic acids include oxalic acid, maleic acid, tartaric acid, citric acid, phosphoric acid, benzoic acid, stearic acid, gallic acid, salicylic acid, 4-oxy-2-naphthoic acid, 0-oxybenzoic acid, 2-oxy- Examples include p-toluic acid, m-oxybenzoic acid, and 4-oxyphthalic acid.

In addition to these leuco dyes and color developers, a binder is used to form the thermosensitive coloring layer. A wide range of known binders can be used, but specific examples include polyvinyl alcohol, methoxycellulose, hydroxycellulose, cal-2xethylcellulose, cal-2xethylcellulose, polyhinylpyrrolidone, polyacrylamide, polyacrylic acid, and starch. , gelatin, etc. are destroyed.

In addition, in combination with these water-soluble binders, for example, polymethacrylic acid such as styrene-butadiene polymer, vinyl chloride-zenyl acetate copolymer, ♂yl acetate, polyacrylic acid ester, polybutyl methacrylate, etc. Latexes such as esters can also be used.

The heat-sensitive coloring layer further contains silica, magnesia, talc,
It is desirable to improve the clarity of the coloring image by adding fine powders such as calcium carbonate, norium sulfate, aluminum stearate, urea-formalin resin, styrene resin, etc. When coating on a support or a lower heat-sensitive coloring layer, antifoaming agents, wetting agents (surfactants), waxes, softening point regulators, etc. are added to the heat-sensitive coloring layer forming liquid. Workability and thermal response can be improved.

In order to produce the multicolor heat-sensitive recording material of the present invention, the leuco dye and color developer are separately mixed with a binder and other additives using a dispersing machine such as a Zeel mill, attritor, or sand mill. After pulverizing and dispersing the particles into fine particles, they are mixed to prepare a heat-sensitive color forming layer forming liquid, and a plurality of heat-sensitive color forming layers may be formed on a support using this liquid.

According to the multicolor heat-sensitive recording material thus obtained, the objects of the present invention can be fully achieved.

Next, examples and comparative examples will be shown.

(Liquid A) Water
A mixture consisting of 200y was ground in a magnetic mill for 24 hours to prepare Solution A.

(Liquid B) 5% polyvinyl alcohol aqueous solution 1 s o g water
200
Solution B was prepared by crushing the mixture consisting of g for 24 hours with a magnetic Seerbal.

(Liquid C) Parabenzoic acid (Nyl ester 12
0p5% polyvinyl alcohol aqueous solution s 20 g water
16
A mixture consisting of
Liquid IIIL9.

(Liquid D) 5% polyhinyl alcohol water! *
t 20g water
A mixture consisting of 160I was ground with an attritor for 3 hours to prepare liquid D.

(Liquid B) CHs (cu 1? -Nu-Co @ 8
G 95% methylcellulose aqueous solution
80g water
A mixture consisting of 240 il was ground with an attritor for 3 hours to prepare Solution B.

Example 1 20 g of the above liquid A, 60 g of liquid D, 30 p of a 20% oxidized starch dissolved aqueous solution, and 40 g of water were mixed and stirred to prepare the first thermosensitive coloring layer forming liquid. 53
Ii/m") with a wire parr and dry to about a
, 5Fl/rrl of the first thermosensitive coloring layer was released.

On this first thermosensitive coloring layer, the above-mentioned B liquid aog, C liquid 60
g, E solution sog and 20% polyvinyl alcohol aqueous solution s
oy and 100 g of water were mixed and stirred, the second layer of heat-sensitive coloring layer type M was applied with a wire spar, and dried to about L8fi/lt? A two-color heat-sensitive recording material was prepared by molding the first heat-sensitive coloring layer, and then surface-treated by calendering to give a Bekk smoothness of 800 to 1200 seconds.

Example 2 Surface treatment 2 was carried out in the same manner as in Example 1 except that the color developer (organometallic compound) in Solution D was replaced with the one below.
Color heat-sensitive recording materials were created.

Example 3 A two-color thermal imaging material was prepared by surface treatment in the same manner as in Example 1 except for replacing the m♂ agent in Solution D with the following.

Comparative Example A surface-treated two-color heat-sensitive recording material was prepared in exactly the same manner as in Example 1, except that the developer in the liquid solution was replaced with 2.2-zes(p-hydro-diphenyl)propane.

These heat-sensitive recording materials were recorded with a triangular wave with a width of 40 cm using a two-color recorder (manufactured by Watanabe Sokki Co., Ltd., two-color recorder) equipped with a thick-film resistor-type heat vent, and the two-color recording material was Separability was investigated. The results are shown in Table 1, which shows that if an organometallic compound is used as a coloring aid in the lower heat-sensitive coloring layer (high-temperature coloring layer), a multicolor thermosensitive brass material with good two-color separation property can be obtained. was confirmed.

When the four types of multi-thermal recording materials mentioned above were examined for image quality and preservation of the background, it was found that the products of the present invention (Examples 1, 2 and 3) showed no change in the background. The stability was good, and on the other hand, the comparative product (the comparative example in which both the first and second heat-sensitive coloring layers used a phenolic compound as a coloring aid) had a noticeable difference in the background. Fog occurred, and decolorization of the red colored image and the black colored image was observed.

Margin below

Claims (1)

[Claims] 1. A colorless or light-colored leuco dye and a plurality of heat-sensitive coloring layers are laminated on the support, and the main component is a color developer that reacts with the leuco dye when heated to form a color. 2. A multicolor thermosensitive recording material characterized in that the color developer in the heat-sensitive color forming layer is an organic metal compound, and the color developer in the upper heat-sensitive color forming layer is an organic acid or a phenolic compound.