JPS58180557A - Fluoran derivative - Google Patents

Abstract

NEW MATERIAL:A fluoran derivative of formula I . USE:A coloring component in heat-sensitive recording materials; a color forming dye in recording paper such as press.-sensitive recording paper or conducting heat-sensitive recording paper. PREPARATION:5-Methyl-4-N-ethylamino-2-hydroxy-2'-carboxybenzophenone of formula II is reacted with 4-methoxy-2'-chlorodiphenylamine of formula III at -10-100 deg.C for several to tens of hr using a condensing agent such as sulfuric acid or polyphosphoric acid. The reaction product is poured into ice water and the deposited crystals are separated from the soln. by filtration. Then, the obtained crystals are dispersed in a 1-20% aq. sodium hydroxide soln. with stirring at 0-100 deg.C for several hr. The crystals are then filtered, dried, and recrystalized from an org. solvent such as toluene, benzene, or isopropyl alc. to yield a fluoran derivative of formula I .

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel fluoran derivative represented by formula (I) and a heat-sensitive recording material using the same as a heat-sensitive coloring component.

Fluorane derivatives are generally used as color-forming components in heat-sensitive recording materials, and are also used as color-forming dyes in recording papers such as pressure-sensitive recording paper and current-carrying recording paper. Among such fluoran dyes, for example, 3-diethylamino-6-methyl-7-chlorofluoran (mp=235 C) has been widely used for red coloring.

However, since such fluorane derivatives have a high melting point of 200 C or more, it has been difficult to obtain a material with good thermal sensitivity when used as a thermal recording medium. In particular, the heat-sensitive recording sheets using fluorane derivatives for red coloring, which have been commonly applied in the past, have poor stability, and when exposed to light for a long period of time, the background becomes red, causing background fog, and red images are It has disadvantages such as discoloration.

The fluoran derivative represented by the formula (I) according to the present invention is an almost colorless substance itself, but
- It has the property of developing a red color when brought into close contact with an electron-accepting substance such as Lure A, and its melting point is 18
5 to 186.5 C, and has excellent thermal sensitivity. Furthermore, the heat-sensitive recording sheet formed using this fluoran derivative has good stability and does not cause coloring during storage, does not cause color fading of the one-tone image, and does not cause significant fogging on the background. .

To synthesize the fluoran derivative of the present invention, as shown in the reaction formula below, 5-methyl-4-N-ethylamino-2-hydroxy-2'-carboxybenzophenone of formula (1) and 4 of formula (1111) are synthesized. -methoxy/-2'-chloro7-phenylamine using a dehydration condensation agent such as sulfuric acid or polyhydric acid at a temperature of -10C to 100C for several hours.
Let it react for several tens of hours. Next, the reactant is poured into ice water, the precipitate is filtered, and the crystals are dispersed in 1 to 20 g of aqueous sodium hydroxide solution and stirred at 0 to 100 C for several hours. The crystals are then filtered, dried, and then recrystallized with an organic solvent such as toluene, benzene, or inpropyl alcohol to obtain a fluoran derivative represented by formula (11).

The heat-sensitive recording notebook using the fluorane derivative of the present invention is
It can be manufactured according to a conventionally known method. That is, the fluoran derivative according to the present invention and a phenolic compound or other electron-accepting substance are coated in a single layer or in multiple layers on a support such as paper, plastic film, cloth, etc. using an inder and then dried and supported. Bye. Furthermore, in the coating layer, CaC0 is added to improve the whitening effect and writability.
a.

Inorganic fillers such as TiO2, ZnO, talc, clay, kaolin, and other organic fillers, as well as any auxiliary additive components commonly used in this type of heat-sensitive recording sheet, may be added.

Next, the present invention will be explained in more detail with reference to Synthesis Examples or Examples.

Synthesis Example 1 (Synthesis of 2-methyl-3-N-ethylamino-7-〇-chloroanilinofluorane) 5-Methyl-1l-N-ethylamino-2-hydroquino-2'-carboxybenzophenone 7 , 18 P and 4-
Methoxy-2'-chlorodiphenylamine 4671 9
Dissolve in 5% sulfuric acid 5Q+++ff and stir at room temperature for about 50 hours. After the reaction is completed, the reaction solution is poured into 500 ml of ice water, and the precipitate is filtered. Next, the crystals were dried in a 5% aqueous sodium hydroxide solution and recrystallized with toluene to obtain almost white crystals 491. mp 185-186.5
U elemental analysis result book) Hydrogen Carbon Nitrogen Calculated value 4.81 72,11 5.80 Actual value 4.
77 72,18 5.76 The coloring hue of the compound obtained in this synthesis example and bisphenol A is deep red, and it also shows red on silica gel.

Example I Liquid A: Water 1
51B liquid: 1 water
After dispersing each of the 5g liquids in a magnetic ball mill for 2 days, liquids A and B were mixed at a ratio of 1:3 (weight ratio), and a 20% aqueous solution of oxidized starch was added to this in a dry weight ratio as follows: A coating solution for a heat-sensitive layer is prepared by adding and mixing the components as follows.

Materials Dry weight ratio 2-Methyl-3-N-ethylamino-7-0-chloroanilinofluorane monoxide starch 16 Next, the standard weight of this coating solution was 52? Dry adhesion amount 4 on one side of /nX high-quality paper
A thermal recording paper sample A was obtained by coating with a wire so as to achieve El/m'.

Comparative Example 1 2-Methyl-3-ethylamino-7-0- in Solution A
A thermal recording paper sample B was obtained in the same manner except that 3-diethylamine-6-methyl-7-chlorofluoran was used instead of chloroanilinofluoran.

Each heat-sensitive recording paper obtained as described above is printed using a facsimile machine (RIFA, X-303) (printing voltage 1
3.08V) Sample A according to the present invention showed a deep red color and an image density of 0.93, whereas sample B for comparison showed a red color and an image density of 0.89. Indicated.

Furthermore, the discoloration density of the background was observed when both the thermosensitive recording papers obtained in Example 1 and Comparative Example 1 were left at 40C1 humidity 95% RH for 24 hours. Concentrations were measured using a Macbeth densitometer using a yellow filter.

The background density of the thermal recording paper of Example 1 was OO8, but in Comparative Example 1, the density was 0.12, which was large in coloring of the background.

The novel fluorane derivative of the present invention provided a heat-sensitive recording sheet which was extremely excellent in thermal sensitivity and image density, and further had less background fog and good storage stability.

Agent: Patent attorney Toshiaki Ikeura

Claims (2)

[Claims] (1) Formula A fluoran derivative represented by A heat-sensitive recording material characterized in that a fluoran derivative represented by the formula (2) is used as a heat-sensitive coloring component.