JPS59190892A - heat sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material excellent in heat responsivity, color developing speed and developed color density and also in preservability of images, by using at least one specified fluoran derivative as a thermal color forming component in a thermal recording material. CONSTITUTION:At least one fluoran derivative of formula I , which is obtained, e.g., by bringing 4-N,N-di-subst.amino-2-hydroxy-2'-carboxybenzophenone of formula II, wherein R1 is a lower alkyl group and R<2> is a lower alkyl group, an aryl group or the like, and 4-methoxy-6-methyl-benzylaniline derivative of formula III, wherein R3 is an electron-attractive group such as halogen, an acyl group or a carboxyl group and R4 is hydrogen or formula IV (wherein R5 is an electron-attractive group) into reaction in the presence of sulfuric acid or the like, is applied to a base together with an ordinary color developer and auxiliary components such as a binder, a filler or a heat-fusible substance to produce a thermal recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material using a fluorane derivative as a heat-sensitive coloring component.

[Prior art]

Fluorane derivatives are used as coloring components in heat-sensitive recording materials, and are also used in heat-sensitive recording paper, current-carrying recording paper,
It is also used as a chromogenic dye in heat-sensitive multiplex paper. Among such fluoran derivatives, for example, 3-N,N-diethylamino-
7-〇-chloroanilinofluorane (mp; 215-2
16°C), 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-anilite fluorane (mp; 2
These fluorane derivatives have a high melting point of 200°C or higher, so when used as a coloring component in a heat-sensitive recording material, it is difficult to find one with good heat sensitivity. It is difficult to obtain these products, and the resulting products are still unsatisfactory in terms of color development speed and color density. Furthermore, the storage stability of recorded images is still unsatisfactory.

〔the purpose〕

The present inventors have conducted various studies to overcome the drawbacks of such fluoran derivatives, and have found that a fluoran derivative with a specific structure exhibits black or red coloring, and that it has a black or red color than the conventional black or red coloring. The present inventors have discovered that it is possible to improve the drawbacks seen in the use of fluoran derivatives exhibiting the following characteristics, and have completed the present invention.

〔composition〕

According to the present invention, there is provided a heat-sensitive recording material characterized in that at least one fluoran derivative represented by the following general formula (1) is used as a heat-sensitive coloring component.

In the above formula, R is a lower alkyl group (the number of carbon atoms is usually 5
), R2 is a lower alkyl group (the number of carbon atoms is usually 5J゜ or less), an aryl group (for example, phenyl,
tolyl, etc.) or an alkyl group (eg, benzyl, phenethyl, etc.). R3 is an electron-withdrawing group, for example, a halogen such as Ct, Br, an acyl group (for example -
COCl-13) and Cal+? Calyf= such as xyl group
It is a substituent represented by a group containing 1.

The fluoran derivative used in the present invention is an electron-accepting substance (color developer) commonly used in the heat-sensitive recording field.
, for example, 4-phenylphenol, 2,2-bis(p
-Hydroxyphenyl)furopane, 4-hydroxyacetophenone, 4-hydroxybenzoic acid hensyl ester, β-naphthol, etc., it develops a black or red color.

Although the compound of the present invention can be synthesized by various methods, for example, it is advantageously synthesized by the following method.

(1) 4-N,N-di-substituted amino-2-hydroxy-2'-hydroxybenzophenone represented by the general formula (R+ and R2 are the same as above); A method of reacting a 4-methoxy-6-methyl-benzylaniline derivative represented by 5- (same as above, R is a methyl group) at room temperature or under heating using a condensing agent such as concentrated sulfuric acid or polyphosphoric acid.

(2) 3-N,N-disubstituted amino-6-methyl-7-aminofluorane represented by the general formula and benzyl halide represented by the general formula in the presence of a basic substance such as pyridine. Alternatively, a heating reaction is carried out without a solvent or in a higher alcohol solvent in the presence of anhydrous potassium carbonate, activated copper powder, and an iodine catalyst if necessary.

When producing a heat-sensitive recording material using the fluoran derivative of the present invention, the color developer may be an organic acid, a metal salt thereof,
Various electron-accepting substances such as phenolic substances and inorganic acids are used, and are used as auxiliary ingredients (such as binders, fillers, thermofusible substances, lubricants, antioxidants, ultraviolet absorbers, etc.). A surfactant or the like is used in combination.

The heat-sensitive recording material of the present invention can have various structures, including all conventionally known structures that utilize a color-forming reaction between a leuco dye and a color developer. For example, the heat-sensitive recording material of the present invention includes a heat-sensitive recording material having a structure in which a fluoran derivative and a color developer are supported on a support as the same coating layer or separate coating layers, and a heat-sensitive recording material in which a fluoran derivative is supported as a transfer layer. It can be used as a thermal transfer type heat-sensitive recording material consisting of a transfer sheet supported by a body and a receptor sheet supported by a support with a color developer as a receptor layer. In the case of a thermal transfer type thermal recording material, a receiving sheet is stacked on a transfer sheet so that its receiving layer is in contact with the transfer layer of the transfer sheet, and the receiving sheet is printed by thermal printing from the front or back side of the polymerized sheet. A desired colored image can be formed on the surface of the receptor layer.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating liquid for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying it. applied to the field of recording.

〔effect〕

The heat-sensitive recording material using the fluoran derivative of the present invention as a color-forming component is significantly superior in thermal sensitivity, color-forming speed, and color-forming density as compared to the conventional material using a fluoran derivative that exhibits a blackish color, and also has excellent image quality. It also has excellent storage stability.

〔Example〕

Next, the present invention will be explained in more detail using examples. Note that all departments and sections shown below are based on weight.

Reference example [3-N,N-diethylamino-6-methyl-7
Synthesis of -(4'-cyanobenzyl)aminofluorane] 40 parts of 3-N,N-diethylamino-6-methyl-7-aminofluoran, 19.6 parts of α-promoparatorni), anhydrous potassium carbonate 7.6 parts and copper powder 0
．． Add 250 parts of isoamyl alcohol to 5 parts to make 110 parts.
The reaction was carried out at ~120°C for 05 hours with stirring. Most of the iso-9-amine alcohol was distilled off using an enovolator, and liproine was added to the reaction mixture, followed by filtration to obtain 23.6 parts of a red-black complex product. The crude product was extracted with a mixed solvent of chloroform and toluene, separated and purified using silica gel column chromatography, further dissolved in toluene, and ligroin was added to reprecipitate to obtain the desired product.

Next, the color hues developed on silica gel of various fluoran derivatives obtained in the same manner as above are summarized in the following table.

Margin below 10- Table = 1 (4-part compounds 168 and 10 to 14 are shown in R4 in Example 1 [Liquid A composition] 10-part aqueous solution of hydroxyethyl cellulose W 4
．． □ tt water
12.0//[B liquid composition] 10% aqueous solution of hydroxyethyl cellulose W
20 tt water
60〃After dispersing each of the above liquids in a Zeel mill for 2 days, 5 parts of liquid A and 5 parts of Bil were mixed,
Furthermore, 8 parts of a 20% aqueous solution of oxidized starch was added and mixed well to obtain a coating liquid for heat-sensitive recording.

Next, the coating liquid was coated on one side of high-quality paper (basis weight 52 p/m") with a dry adhesion amount of 4 f/m" and a smoothness of 130 to 20.
A heat-sensitive recording sheet was prepared by applying the mixture for 0 seconds.

Example 2 In Example 1, instead of the fluoran derivative of liquid A,
3-N,N-di-n-butylamino-6-methyl-7-
(2'-chlorobenzyl)aminofluorane (71 above)
A heat-sensitive recording plate was prepared using Compounds i and 5) and in the same manner.

Example 3 In Example 1, instead of the fluoran derivative of liquid A,
, 3-N-p-tolyl-N-ethylamino=6-
A heat-sensitive recording sheet was prepared in the same manner except that #chill-7-(4'-chloro-4-acyl)aminofluorane (compound A9 above) was used.

Example 4 In Example 1, instead of the fluoran derivative of liquid A,
3-N,N-diethylamino-6-methyl-7-(4'
A heat-sensitive recording sheet was prepared in the same manner except that hydroxypennor)aminofluorane (compound No. 3 above) was used.

Example 5 In Example 1, 3-N,N-dibutylamino-6-methyJl/3-N,N-dibutylamino-6-methyJl/
A thermosensitive recording sheet was prepared in the same manner using -7-N, N-)-3'-chlorobenzylaminofluoran (compound j614 above).

Comparative Example 1 In Example 1, instead of the fluoran derivative of liquid A,
A heat-sensitive recording sheet was prepared in the same manner except that 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, which has been widely used in the past, was used.

Comparative Example 2 In Example 1, instead of the fluoran derivative of liquid A,
Conventionally widely used 3-N,N-diethylamino-
A heat-sensitive recording sheet was prepared in the same manner except that 7-orthochloroanilinofluorane was used.

In order to evaluate each of the heat-sensitive recording sheets obtained above, tests were conducted regarding heat sensitivity and storage stability.

The results are shown in the table below.

Thermal sensitivity: - by facsimile simulator
14- The thermal head was brought into contact with the thermal recording sort under the conditions of a constant application time (0.94 ms [! (: )) and a constant applied voltage (20 V), and the resulting color density was measured using a Macbeth densitometer. The color density was evaluated.

Preservability...Thermal recording sheet with recorded image-1.
was left in an atmosphere of 40°C and humidity of 90 parts RH for 24 hours, and the degree of change in the density of the image area and the density of the non-image area was measured and evaluated.

In this case, the image density before storage indicates the density when color is developed by heating at 120° C. and pressure 2 for 2.1 seconds.

bottom margin Table-2 Patent applicant Ricoh Co., Ltd. Representative Patent Attorney Toshiaki Ikeura

Claims (1)

[Claims] (1) General formula (wherein RI is a lower alkyl group 5, R2 is a lower alkyl group, aryl group or aralkyl group, R3 is an electron-withdrawing group, R4 is a hydrogen atom or a substituent represented by the formula ) A heat-sensitive recording material characterized in that at least one fluoran derivative represented by the following is used as a heat-sensitive coloring component.