JPH01208183A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material superior in color forming properties, by incorporating a 1-benzyloxy-4-phenoxymethylbenzen in a thermal recording layer as a color forming accelerator. CONSTITUTION:A thermal recording material is formed by applying a thermal recording layer containing a leuco compound, an organic acid as a color developer, a binder, and a 1-benzyloxy-4-phenoxymethylbenzen shown by a formula I as a color forming accelerator on a substrate. This 1-benzyloxy-4- phenoxymethylbenzen is preferably contained in the amount of 1-50wt.% to the total solid content of the thermal recording layer from the standpoint of color-forming accelerating properties, but the amount of 10-40wt.% is optimum. Each component has an advantage in color forming efficiency if being atomized as fine as possible. Thus, a heat-sensitive coating material atomized to 0.5-3mum in particle diameter is applied to the substrate and dried to obtain the thermal recording material.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention mainly consists of a colorless or light-colored organic dye generally called a leuco compound, and an organic acid such as a phenol compound that develops a color by reacting with the leuco compound. This invention relates to improvements in thermosensitive recording materials.

[Conventional technology]

A thermosensitive recording paper containing a leuco compound and an organic acid is already known, for example, from Japanese Patent Publication No. 14039/1983. This recording paper applies thermal energy to the recording layer to soften or melt the leuco compound, organic acid, and binder.
It is based on the principle of bringing color-regenerating components into contact and causing a color reaction, and has recently been used in various fields such as printers and facsimile machines. The recording characteristics of this recording paper vary depending on the use, but in order to increase the recording speed, for example, it is necessary to improve the recording device and to promote the color development of the recording paper itself.

A commonly used method for promoting color development is to include a low melting point substance in the recording layer. As a low melting point substance, that is, a color accelerator or a sensitizer,
No. 60 uses urea, phthalic anhydride, and acetanilide, and JP-A-48-19231 uses paraffin wax 1. Carnauba wax, beeswax, wood wax, higher fatty acids, higher resin acid esters, and in Japanese Patent Publication No. 49-17748, salicylic acid, anisic acid, phthalic acid monophenyl ester, phthalic acid monobenzyl ester, and near sheep fatty acid amide. It is also widely used as a color accelerator.

That is, Japanese Patent Publication No. 51-27599 describes the sensitizing effect of fatty acid amide by the combination of paraffin or microwax and fatty acid amide.
The sensitizing effect of fatty acid amides such as stearic acid amide and oleic acid amide is also described in this issue and is well known.

[Problem to be solved by the invention]

However, the effects of conventional color development accelerators cannot be said to be sufficient, and there has been a strong demand for technology that provides even better color development.

The present inventors confirmed the effects of these conventional color accelerators, and in order to discover substances with even better properties,
As a result of various studies, we have discovered a new color development accelerator that has remarkable effects, and based on this knowledge, we have accomplished the present invention.

[Means to solve the problem]

That is, the present invention provides a heat-sensitive recording material mainly composed of a leuco compound and an organic acid that develops a color by reacting with the leuco compound, in which a color development accelerator represented by the following structural formula (I) is used as a color development accelerator in the heat-sensitive recording layer. It will be done.

It is constructed to contain 1-benzyloxy-4-phenoxymethylbenzene.

Structural formula (I) The present invention will be explained in detail below.

The heat-sensitive recording material of the present invention supports a heat-sensitive recording layer containing a leuco compound, an organic acid as a color developer, a binder, and 1-benzyloxy-4-phenoxymethylbenzene as a color development promoter. It consists of something coated on the body.

1-benzyloxy-4-phenoxymethylbenzene, which is used as a coloring promoter used in the present invention, has an excellent coloring promoting effect, and also has other properties as a heat-sensitive recording material, such as background density, background fogging and discoloration after storage, etc. It also has characteristics that pose no problem in practical use.

The content of l-benzyloxy-4-phenoxymethylbenzene is preferably 1 to 50% by weight of the total solid content of the heat-sensitive recording layer from the viewpoint of promoting color development. More preferably 10-4
0% is most appropriate.

The leuco compounds used in the present invention are colorless to light-colored substances that develop color by reacting with organic acids, such as triphenylmethane, triphenylmethanephthalide, fluoran, leucoolamine, diphenylmethane, and phenothiazine. Examples include various derivatives such as phenoxazine-based, phenoxazine-based, spiropyran-based, indoline-based, and indigo-based. Preferred leuco compounds include, for example, crystal violet lactone, 3-diethylamino-6-methyl-
7-aniline fluorane, 3-(N-ethyl-P-toluidino)-6-methyl-7-anilinofluorane, 3-
Diethylamino-6-methyl-7-(ortho, para-dimethylanilino)fluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-
Methyl-7-anilinofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-7-(ortho-chloroanilino)fluorane, 3-diethylamino- 7-
(Meta-trifluoromethylanilino)fluorane, 3
-diethylamine-6-methyl-chlorofluorane, 3
-diethylamine-6-methyl-fluorane, 3-cyclohexylamino-6-chlorofluorane, 3-(N-
isoamyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-
7-anilinofluorane is mentioned.

The organic acid used in the present invention is a substance that is solid at room temperature, melts by heating, and becomes a color developer when it comes into contact with a leuco compound, and includes various phenolic substances, fatty acids, aromatic carboxylic acids, and the like. Examples include gallic acid, salicylic acid, l-hydroxy-2-naphthoic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxy-
f)-) Ruylic acid, 3,5-xylenol, thymol,
p-tert-butylphenol, 4-hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-
Hydroxyacetophenone, α-naphthol, β-naphthol, catechol, resorcinol, hydroquinone, 4-
tert-octylcatechol, 4. 4'-5ec
-butylidenephenol, 2,2'-dihydroxydiphenyl, 2°2'-methylenebis(4-methyl-5-t
ert-butylphenol), 2,2'-bis(4'-
hydroxyphenyl)propane (also known as bisphenol A), 4,4'-isopropylidene-bis(2-ter
t-butylphenol), pyrogallol, phloroglucin, phloroglucincarboxylic acid, p-methylphenol, p-phenylphenol, 4.4'-cyclohexylidene diphenol, 4.4'-(I-methyl-n- xylidene) diphenol, 4,4'-isopropylidene dicatechol, 4,4'-benzylidene diphenol,
4.4'-isopropylidene bis(2-chlorophenol), 3-phenylsalicylic acid, 3.5-ter
t-Butylsalicylic acid, 1-oxy-2-naphthoic acid, gallic acid ester, salicylic acid ester, p-hydroxybenzoic acid ester, 4-hydroxyphthalic acid ester, 2-(4-hydroxyphenyl)-2-(3'- hydroxyphenyl)propane, 4,4'-dihydroxy-3,3'-diisopropyldiphenyl-2,2'-
Examples include propane, but those with a melting point of 120°C or higher are preferred.

The binder used in the present invention is mainly a water-soluble binder, which separates and fixes the coloring agent dispersed in fine particles from each other, and includes polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, Examples include acrylic acid, casein, gelatin, starch and derivatives thereof.

The heat-sensitive recording layer of the present invention may optionally contain other additives, such as clay, calcium carbonate, aluminum hydroxide, talc, titanium oxide, silica, zinc oxide, and other inorganic or organic pigments, waxes, and preservatives. Antioxidants for stability, ultraviolet absorbers, various fatty acid metal salts to prevent stickiness, water resistant agents to improve water resistance, phenolic resins, surfactants, etc. can be added.

The coating material for a heat-sensitive recording layer of the present invention comprises the above-mentioned leuco compound;
An organic acid, 1-benzyloxy-4-phenoxymethylbenzene, and additives such as pigments and sensitivity adjusters as needed are ball milled in an aqueous medium containing a binder such as polyvinyl alcohol at an appropriate concentration. It is generally prepared by grinding and dispersing using a grinder such as a sand grinder. It is advantageous in terms of color development efficiency to make each component material as fine as possible, and preferably to have a particle size of 0.5 to 3 microns. The heat-sensitive paint thus obtained is applied to the support described below and dried to obtain the heat-sensitive recording material of the present invention.

Coating can be done using a regular blade coater, air knife coater,
This can be done using a bar coater, reverse roll coater, or the like.

The support used in the present invention generally includes high-quality paper,
Papers such as medium-quality paper and coated paper are used, but other materials such as glass fiber sheets, plastic sheets, and film-laminated papers can also be used as the support.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 a) Production of heat-sensitive recording material Liquids A and B having the following compositions were prepared by separately dispersing them in a paint shaker (Toyo Seiki model) for 10 hours.

Solution A: Leuco dye 3-dibutylamino-6methyl-7-anilinofluoran 7-anilinofluoran 5g1-benzyloxy-4-phenoxymethylbenzene
8g zinc stearate
5g polyvinyl alcohol 12% liquid 3
5 g water
47g Solution B: Bisphenol A 15g Zinc stearate 3g Polyvinyl alcohol water 47
g Next, add 100 g of liquid A, 100 g of liquid B, 50 g of 12% polyvinyl alcohol liquid, 15 g of synthetic silica P-832 (manufactured by Mizusawa Chemical Co., Ltd.), and 60 g of water and mix. Next, apply this coating liquid to the surface of 50 g/- of high-quality paper using a Mayer bar until the coating amount after drying is 8 g/-.
The mixture was coated and dried to obtain heat-sensitive recording paper.

Example 2 Among the formulations of liquid A used in Example 1, 3 were used as leuco dyes.
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that -(N-isoamyl-N-ethyl)amino-6-methyl-7-anilite fluorane was used.

Comparative Example 1 A thermosensitive recording paper was obtained in the same manner as in Example 1, except that 1-benzyloxy-4-phenoxymethylbenzene in liquid A used in Example 1 was removed.

Comparative Example 2 Among the liquid A formulations used in Example 1, 1-benzyloxy-
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that stearamide was used instead of 4-phenoxymethylbenzene.

Comparative Example 3 Among the A liquid formulations used in Example 1, 1-benzyloxy-
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that parabenzylbiphenyl was used instead of 4-phenoxymethylbenzene.

Comparative Example 4 Among the liquid A formulations used in Example 1, 1-benzyloxy-
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 2-benzyloxynaphthalene was used instead of 4-phenoxymethylbenzene.

The heat-sensitive recording papers obtained in the above Examples and Comparative Examples were surface-treated with a test super calender so that the recording surface had a Beck smoothness of 500 seconds.

The thermal recording paper obtained by this surface treatment is commercially available (7
) GI [I7y Kushimiri device FAcOM FAX 62
1G (manufactured by Fujitsu), recording power 0.90 w/dat
, energizing time 0.45m5ec, cycle approximately 5m5ec
Printing was carried out under conditions of 1/1, and the image density and background density at the time of printing were measured using a Macbeth densitometer. The storage stability was the concentration after 24 hours of storage in a constant temperature room maintained at 60°C in a dry state. The results shown in the table below were obtained for the Examples and Comparative Examples.

Table [Effects of the Invention] From the table, it was demonstrated that the heat-sensitive recording material of the present invention has excellent characteristics in terms of sensitivity and storage stability.

Claims (1)

[Scope of Claims] A heat-sensitive recording material comprising, on a support, a heat-sensitive recording layer containing a leuco compound, an organic acid that develops a color by reacting with the leuco compound, and a binder, wherein the heat-sensitive recording layer A heat-sensitive recording medium characterized by containing 1-benzyloxy-4-phenoxymethylbenzene represented by the following structural formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ Structural formula (I).