JPS60185760A - Novel phenolic compound - Google Patents

Abstract

NEW MATERIAL:1,8-Di(4-hydroxyphenylthio)-3,6-dioxaoctane of formula. USE:A color developer of leuco dye. It has excellent high-speed recording performance, and high storage stability at room temperature. It is free from phenolic smell. It can be synthesized easily, in high yield and purity, at a relatively low cost, and has high practical value. PREPARATION:The compound of formula can be prepared by reacting monothiohydroquinone with the corresponding dihalogenoalkyl ether under alkaline condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a novel phenolic compound useful as a color developer for leuco dyes.

[Prior art]

Thermosensitive recording materials that utilize a color-forming reaction between a leuco dye and a color developer are known. In recent years, with the development of society, there has been an increasing demand for faster and higher recording density in such recording materials.

For this reason, there is a strong desire not only to increase the speed of the recording apparatus itself, but also to develop recording materials that can support this speed. Therefore, from this point of view, Japanese Patent Application Laid-Open No. 53-39139 and Japanese Patent Application Laid-open No. 53-2
No. 6139, JP-A-53-5636, JP-A-53-1
No. 1036, etc., further contains a sensitizer (or melting point) heat-melting substance such as various waxes, fatty acid amides, alkylated biphenyls, substituted biphenylalkanes, coumarins, and diphenylamines in the heat-sensitive coloring layer as described above. It has been proposed that it be added as a depressant). However, in the method of adding a sensitizer, it is necessary to melt the sensitizer before the color reaction occurs, so it is difficult to obtain sufficient thermal response in high-speed recording where only a small amount of heat is supplied in a short pulse. However, since the sensitizer in the coloring layer melts, there are problems with recording suitability such as adhesion of residue to the thermal head, smearing, trailing, ghosting, and other problems. Furthermore, when stored at high temperatures and/or high humidity, fogging occurs over time and often reduces the contrast of recorded images. Therefore, it is desirable that a heat-sensitive recording sheet for high-speed recording has a structure in which no sensitizer is added.

However, colorless or light-colored color-forming dyes used in heat-sensitive recording sheets usually have a high temperature of 160 to 240°C, so in order to construct a heat-sensitive color-forming layer suitable for high-speed recording without adding a sensitizer, it is necessary to have a low melting point. Moreover, it is essential to use a color developer that has a large ability to develop color from the color former. By the way, there are many descriptions of color developers, especially phenolic compounds, in combination with colorless or light-colored dyes in various documents, including Japanese Patent Publication No. 45-14039, but among these, bisphenol A has a stable quality. It is widely used due to its low price and easy availability. However, since this bisphenol A has a high melting point of 156 to 158°C, it has the disadvantage of low thermal sensitivity (and therefore high thermal coloring temperature).

In contrast, phenolic compounds with low melting points, such as 4
-Thermosensitive recording when using monophenols such as t-butylphenol (melting point 94-99°C), α-naphtol (melting point 95-96°C), and β-naphthol (melting point 119-122°C) Sea 1- has poor storage stability, gradually fogging occurs even at room temperature, and has a strong so-called phenol odor, making it impractical. In addition, special public service
819 contains 2,2-bis(4-hydroxyphenyl) normal hexane (melting point 99-103°C), and JP-A-55-272FiB contains 1,1bis(4-hydroxyphenyl)alkane (alkane). Carbon number is 3-13)・
! It is described that a heat-sensitive recording sheet with high heat sensitivity, storage stability, and color development can be produced using each of these substances, but all of these substances are difficult to synthesize and have problems in availability. Furthermore, in JP-A-56-144193, p.
- It has been described that lower alkyl esters or benzyl esters of hydroxybenzoic acid are easy to synthesize and can be used to make highly sensitive heat-sensitive recording sheets, but the colored portions of these sheets fade over time. Moreover, it has the drawback in terms of storage that crystals of the phenolic compound precipitate (so-called white powder phenomenon).

As described above, the leuco dye color developer applied to the conventional heat-sensitive recording sheet 1- for high-speed recording has advantages and disadvantages, and has not yet been practically satisfactory.

〔the purpose〕

An object of the present invention is to provide a novel phenolic compound that has excellent suitability for high-speed recording, excellent storage stability at room temperature, and is extremely practical as a leuco dye developer without phenol odor.

〔composition〕

The present inventors have conducted various studies to achieve the above object, and as a result, have found that the phenol compound represented by the formula is suitable for the purpose, and have completed the present invention.

The phenolic compound of the above formula used in the present invention can be easily synthesized in high yield, high purity, and relatively inexpensively by reacting monothiohydroquinone with the corresponding dihalogenoalkyl ether under alkaline conditions. can.

The phenolic compound of the present invention is bisphenol A (m, 1.
(155-157°C), it can be used as a color developer suitable for heat sensitivity and high-speed recording applications. It is excellent in both the stability of the coloring part and the high-speed coloring property, and is conventionally used as a high-speed coloring developer.
-Hydroxybenzoic acid benzyl ester (m, 'p, 1
11 to 112° C.), there is a disadvantage that the colored portion loses its color over time, but the phenolic compound of the present invention does not have such a disadvantage.

When producing a heat-sensitive recording material using the compound of the present invention as a color developer, conventionally known leuco dyes (colorless or light-colored color-forming dyes) may be used in combination with such phenolic compounds, such as The following may be mentioned.

Crystal Violen 1 - Lactone 3-diethylamino-6-methyl-7-anilinofluoran 3-diethylamino-6-methyl-7(o+p-dimethylanilino)fluoran 3-(N-ethyl-p-toluidino)-6- Methyl-7
-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane 3-piperidino-6-methyl-7-anilinofluorane 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-ayurifluoran 3-diethylamino-7-(o-chloroanilino)fluoran 3-diethylamino-7-(m-f-lifluoromethylanilino)fluoran 3-diethylamino-6-methyl-7-chlorofluoran Oran 3-diethylamino-6-methylwallaolan 3-cyclohexylamino-6-chlorofluoran The ratio of the leuco dye to the phenolic compound of the above formula is preferably about 11 to 6 (by weight).

The heat-sensitive recording material obtained by using the phenolic compound of the present invention thus obtained as a color developer has the following features.

(1) Since the product can be manufactured without using a sensitizer or a melting point depressant, it has particularly excellent thermal responsiveness, and therefore high sensitivity and clear images can be obtained.

(2) For the same reason as in (1) above, fogging does not occur even under high temperature or high humidity, and image contrast does not deteriorate.

(3) For the same reason as in (1) above, there are no problems such as adhesion of residue on the thermal head, bleeding, trailing, ghosting, etc., and the recording suitability is excellent.

(4) By using the phenolic compound of the above formula, fogging does not occur at room temperature and phenol odor does not occur, making it extremely practical.

(5) The phenolic compound of the above formula is easy to synthesize, so there are no problems in obtaining it, and moreover, it can be obtained in high yield, with high purity, and at relatively low cost.

(6) For the same reason as mentioned in (4) above, the colored image does not fade over time or cause white powder phenomenon, and is very stable.

For similar reasons, it also has the following features:

(7) Those using thin base paper or film as a support are particularly excellent as thermal recording materials for infrared rays and strobe flash type thermal copying.

(8) It is possible to reduce the amount of coating and improve production efficiency.

〔Example〕

Examples of the present invention are shown below. In addition, in the following, part 1
% is parts by weight and % by weight, respectively.

Example 1 6.4 g of sodium hydroxide is dissolved in 22 g of methanol, and 20.2 g of P-hydroxybenzenethiol is added. Next, 13.7 g of 1.2 bis(2-chloroethoxy)ethane was added dropwise to this mixture at room temperature, and after the addition was completed,
The reaction was heated under methanol reflux conditions for 2 hours. After heating, the mixture was cooled and methanol was distilled off under reduced pressure. 500 mQ of water was added to the residue, and the precipitated crystals were collected by filtration and thoroughly washed with water. After drying, it was recrystallized from a mixed solvent of 1-luene-ethyl acetate to obtain white crystals of 1,8-di(4-hydroxyphenylthio)-3,6-thioxaoctane (17.7%).
I got g. Melting point 100-101"C0 Elemental analysis results 11i, u L! Theoretical value 58.99% 6.05% 17.50% Synthetic product 58.69% 5.91% 17.44% Application example Mixtures of the following formulations, respectively The mixture was pulverized and dispersed in a magnetic ball mill for 2 days to prepare liquids A, B, and C.

A111 is 3-(N-cyclohexyl-N-20-methylamino)
-6-Methyl- 20 parts of 7-anilitufluorane hydroxyethylcellulose 10% aqueous solution 60 parts of water 1 Ryo Co., Ltd. 20 parts of 8-di(4-hydroxyphenylthio)-3
, 6-Sioxaoctane (melting point 100-101°C) 10% hydroxyethylcellulose 20 parts aqueous solution 60 parts S'1 6-precipitated calcium carbonate 20 parts 5% aqueous methyl cellulose solution 20 parts water 6o parts Obtained as above Using the obtained solutions (A) to (C), a thermosensitive coloring layer solution having the following composition was prepared, and the standard basis weight was 50 g/nF.
A wire bar was selected and applied to a commercially available high-quality paper with a dry coating amount of 4 to 5 g/rf, and dried, and then a calendar was applied so that the smoothness of the surface of the heat-sensitive coloring layer was 500 to 600 seconds in Bekk smoothness. Comparison of 20% alkaline aqueous solution of copolymer with poppy and heat-sensitive recording sheet (a) 5 [A] 10 parts by weight (B) liquid 30 parts by weight (C) liquid 30 parts by weight Isobutylene-maleic anhydride 10 parts by weight Example 1 A thermosensitive recording sheet (b) was prepared in the same manner as in the applied example except that the following liquid (1) was used instead of the liquid (B) in the applied example.

CD) Liquid bisphenol A 20 parts 10% of hydroxyethyl cellulose 20 parts Aqueous solution 60 parts Comparative Example 2 Thermal recording was carried out in the same manner as in the application example except that the following liquid (E) was used instead of liquid (B) in the application example. I made a sheet (C).

[E] Liquid benzyl p-hydroxybenzoate 20 parts 10% of ester hydroxyethyl cellulose 20 parts Aqueous solution 60 parts or more Each of the heat-sensitive recording sheets obtained as described above was heated to G-11.
1 Printing at high speed using a facsimile device (Rifux 3300 manufactured by 1 Noko) (Printing speed: 0.94.m5ec,
Applied voltage: 16 V, 18 V, 20 V) L, and the color density was measured using a Macbeth densitometer RD-514 (manufactured by Macbeth). The results are shown in Table-1.

In addition, the above printed matter (printing speed: 0.94m5ec,
After allowing the sample to stand for one week, the color density was measured again using a Macbeth densitometer RD-514.

In addition, white powder phenomenon in the colored area was also observed at that time. The results are shown in Table-2.

Table 1 *Comparative Example Table 2 *Comparative Example Table 1 and Table 2 As clear from Table 1 and Table 2 of Comparative Examples, the heat-sensitive recording material formed using the phenolic compound of the present invention as a color developer exhibits color development during high-speed recording. It can be seen that it is a heat-sensitive recording material with excellent color image contrast and extremely stable colored images.

Patent applicant Rico Co., Ltd. Representative Patent Attorney Toshiaki Ikeura

Claims (1)

[Claims] (1) Formula A phenolic compound represented by