JPH0236992A - Heat-sensitive recording medium - Google Patents

Abstract

PURPOSE:To obtain a heat-sensitive recording medium with a superior color development property by adding cyclohexanone oxime as a color development accelerator in the heat-sensitive recording layer of a heat-sensitive recording medium containing a leuco compound, an organic acid and a binder. CONSTITUTION:A base is coated with a heat-sensitive recording medium consists of a heat-sensitive recording layer, which contains a leuco compound, a binder for an organic acid as a color developer and cyclohexane oxime as a color development accelerator. The preferable mixture percentage of cyclohexane oxime is 50% by weight of the total solid amount of the heat-sensitive recording layer from a viewpoint of color development acceleration. It is advantageous for color development effects to powder each constituent material, preferably to the particle diameter of 0.5-3mum. A heat-sensitive recording medium is obtained by applying heat-sensitive paint to the surface of the base.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a colorless or light-colored organic dye generally called a leuco compound, and a major acid such as a phenol compound that develops color by reacting with the leuco compound. (Prior art) A thermosensitive recording paper containing a leuco compound and an organic acid is well known, for example, from Japanese Patent Publication No. 45-14039. .This recording paper applies thermal energy to the record 1 to soften or melt the leuco compound, organic acid, and binder.
It is based on the principle of bringing color 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 82 recording device and to promote the color development of the recording paper itself.

A common method for promoting color development is to include a low melting point substance in the recording layer. For example, as a bottom melting point substance, i.e. a color accelerator or a sensitizer,
No. 3-4160: urea, fucuric anhydride, acetanilide, and JP-A No. 19231: paraffin wax, carnauba wax, wood wax, higher fatty acids, higher fatty acid esters; In the issue, salicylic acid, anisic acid, fucuric acid monophenyl ester,
One dose of fucuric acid monopencyl ester is used. In recent years, fatty acid amides have also been widely used as color accelerators. For example,
No. 9 discloses the sensitizing effect of fatty acid amide by combining paraffin or microwax with fatty acid amide, and JP-A-54-139740 discloses the sensitizing effect of fatty acid amide such as stearic acid amide and oleic acid amide. ing.

(Problems to be Solved by the Invention) However, the effects of these conventional color development accelerators cannot be said to be sufficient, and there has been a strong demand for a technique that provides even better color development.

The present inventors have conducted extensive and deep studies to find a coloring agent that has even better properties than these conventional coloring accelerators, and have discovered a new coloring accelerator that has remarkable effects. Based on this knowledge, we have completed the present invention.

(Means for Solving the Problems) Zunawaji, the present invention provides a heat-sensitive recording material containing a leuco compound, an organic acid that develops a color by reacting with the leuco compound, and a binder, in which a heat-sensitive recording material is provided in the heat-sensitive recording layer. It is constructed to contain cyclohexanone oxime as a color development accelerator.

The present invention will be explained in detail below.

The heat-sensitive recording material of the present invention has a heat-sensitive recording layer containing a leuco compound, an organic acid as a color developer, a binder, and 7-chlorohexanone ochine as a color development accelerator, coated on a support. It consists of things.

Cyclohexanone oxime as a color development accelerator used in the present invention is excellent in the effect of promoting color development, and also has other properties as a heat-sensitive recording material, such as background density, background fluctuation after storage, discoloration, etc. It also has very excellent properties.

The content of cyclohexanone oxime is preferably 1 to 50% by weight of the total solids of the heat-sensitive recording material from the viewpoint of promoting color development.'7).

In addition, a known color development promoter may be added to the recording layer in combination with the color development promoter of the present invention.

The leuco compounds used in the present invention are colorless to light-colored substances that develop color by reacting with organic acids, and include triphenylmethane, triphenylmethane phthalide, fluoran, leuco auramine, and diphenylmethane compounds. ,
Examples include various derivatives such as phenothiazine, phenoxazine, spiropyran, indoline, and indigo derivatives. Preferred leuco compounds include, for example, crystal high oleene raftone, 3-diethylamine-6methyl-7-anilinofluorane, 3-(N-ethyl-P-
toluidino)-6-methyl-7-anilinofluorane,
3-diethylamine-6-methyl-7-(ortho, para-dimethylanilino)fluoran, 3-pyrrolidino-6
-Mediru-7-anilinofluorane, 3-piperisino-6-methyl-7-anilinofluorane, 3-(N-7chloroheki/ru-N~methylamine)-6-methyl-7anilinofluorane, 3 -diethylamine-7(ortho-chloroanilino)fluoran, 3-diethylamino-7-(
mekutrifluoromethylanilino)fluorane, 3-
Diethylamine-6-methyl-chlorofluorane, 3-diethylamine-6-methyl-fluorane, 3-chlorohequinylamine-6-chlorofluorane, 3-(N-yneamyl-N-edylamino)-6-methyl-7ani Examples include linofluoran and 3-dibutylamino-6methyl-7-anilinofluoran.

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, 1-hydroquine-2-naphthoic acid, O-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroquine-p-
Toluyl L 3,5-quinlenol, thymol, pte
rt-butylphenol, 4-hydroxyphenoxyto, methyl-4-hydroxybenzoate, 4-hytroquine acetophunone, α-naphthol, β-naphthol,
Catechol, resorcin, hydroquinone, l) -te
rt-octylcatechol, 44'-5ec-phthylidenephenope 2.2'-phthylidene diphenyl, 2
．． 2'-methylenebis(4-methyl-6-tert-
butylphenol), 2,2'-bis(4'-hydroxyphenyl)propane (also known as bisphenol A>, 4
．． 4'-impropylidene-bis < 2-tert-butylphenol), pyrogallol, phloroglucin, fluorotarunnecarboxylic acid, p-methylphenol, p-phenylphenol, 4.4'-cyclohequinylidene diphenol, 4.4' -(1-methyl n-hequinylidene) diphenol, 4.4' isopropylidene dicatechol, 4.4' -benzylidene diphenol, 4,4'
-isopropylidene bis(2-1'lolphenol),
3-phenylsalicylic acid, 3,5-tert-butylsalicylic acid, 1-oquino-2-naphthoic acid, gallic acid ester, salicylic acid ester, p-hydroquine benzoate, 4-hydroquine fucuric acid ester, 2-(
4-Hydroquinphenyl)-2-(3'hydroxyphenyl)propane, 4,4'-dihydroxy-33'-
Examples include diisopropyldiphenyl-2,2'-propane.

The binder used in the present invention is mainly a water-soluble binder, which separates and fixes the coloring agent dispersed in fine particles, and includes polyvinyl alcohol, methylcellulose, carboxydimethylcellulose, and hydroxyethylcellulose. , polyacrylic acid, casein, gelatin, starch and their derivatives.

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

The paint for a heat-sensitive recording layer of the present invention comprises the above-mentioned leuco compound,
Organic acids, cyclohexanone oxime, and additives such as pigments and sensitivity adjusters as needed are mixed in an aqueous medium containing an appropriate concentration of a binder such as polyvinyl alcohol. It is generally prepared by grinding and dispersing using a grinder such as a grinder. It is advantageous in terms of color development efficiency to make each component material as fine as possible.
It is preferable to atomize the particles to a particle size of 0.05 to 3 μm.

The heat-sensitive paint thus obtained is applied to a support described below and dried to obtain the heat-sensitive recording material of the present invention.

Coating is done using a regular blade coater, air knife caulk,
This can be done using bar caulk, reverse roll coater, etc.

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 paper can also be used as the support.

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

Example 1 Solutions A and B having the following compositions were prepared by separately dispersing them in a paint shaker (manufactured by Toyo Josei Co., Ltd.) for 10 hours.

Solution A 3-dibutylamino-6-methyl-7-anilinofluorane (Leuco Somebokuto) g Cyclohexanone ochim 8 g Zinc stearate 5 g Holvinyl alcohol 12% solution 35 g Water
47gB solution: Bisphenol Δ 15g zinc stearate 3g polyhinyl alcohol 12% solution 35g water
47g Next, add 100g of liquid A and 1 part of liquid B.
00g, 50g of 12% polyvinyl alcohol solution, 15g of synthetic silica P832 (manufactured by Mizusawa Chemical Co., Ltd.), and 60g of water.
g and stirred to make a coating liquid, and then applied this coating liquid to the surface of 50 g/m' high-quality paper using a Mayer bar so that the coating amount after drying was 8 g/m'. 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-ynamyl-N-ethyl)amino-6-methyl-7-anilite fluorane was used.

Comparative Example 1 A thermosensitive recording paper was obtained in exactly the same manner as in Example 1 except that cyclohexanone oxime in the liquid A used in Example 1 was omitted.

Comparative Example 2 A thermosensitive green paper was obtained in the same manner as in Example 1, except that stearic acid amide was used instead of nclohexanone oxime in the mixture of liquid No. 7 used in Example 1.

Comparative Example 3 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that parabennorhyphenyl was used instead of cyclohexanone oxime in the formulation of Liquid A used in Example 1.

Comparative Example 4 Thermosensitive recording paper was obtained in the same manner as in Example 1 except that 2-pencil oquinnafculene was used instead of cyclohexanone oxime in the formulation of liquid A used in Example 1. .

The heat-sensitive recording papers obtained in the above Examples and Comparative Examples were surface-treated with a test super xarender so that the recording surface was 500 seconds on a Beck scale.

Regarding the thermal recording paper obtained by this surface treatment, commercially available G
Facunmill device FACOM FAX621C (Fujitsu (hard mounted), recording power 0.90 W/dat, energizing time Q, 45 m5ec, cycle approximately 5 msec/
Printing was carried out under the conditions of 1, and the image density and background density of the printed image 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 of Examples and Comparative Examples are shown in Table 1 below.

From Table 1, it can be seen that the density of the recorded image and the background density were not affected, and even after storage, the decrease in the image density was small, making it a very good thermal recording material.

Table-1

Claims (1)

[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 contains cyclohexanone oxime. A heat-sensitive recording material characterized by the following properties.