JPS61192589A - Thermal recording paper - Google Patents

Abstract

PURPOSE:To obtain thermal recording paper suitable for high density and high speed recording and imparting a color image stable to the adhesion of a hair conditioner or oils and fats, in thermal recording paper having a thermal color forming layer containing a basic leuco dye and an org. coupler, by containing a specific naphthol derivative as the org. coupler. CONSTITUTION:A naphthol dericative represented by formula (I) or (II) (wherein X is -SO2-R or -COR and R is a 1-12C alkyl group or a 5-10C cycloalkyl group) is contained in a thermal color forming layer as an org. coupler. Because this compound as the org. coupler is a naphthol derivative having a sulfonic ester group or a carboxylic ester group in its molecule, the melting, dissolving and diffusing speed and saturated solubility of a basic leuco dye to said compound are extremely large. As a result, the org. coupler and the basic leuco dye become instantaneously compatible by heating to form a color forming composition. Because the chemical bonding force in this color forming process is especially strong, said bond is not cut even if a hair conditioner or oils and fats is adhered and a developed color image is stable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-sensitive recording paper that is suitable for high-density and high-speed recording and that provides stable colored images against adhesion of hair styling products and oils and fats.

(Prior art) A thermosensitive recording paper that utilizes a color-forming reaction by heating between a so-called basic colorless dye, which is usually colorless or light-colored, and a color developer such as a phenol or an organic acid, is disclosed in Japanese Patent Publication No. Sho, No. d3-4160, Japanese Patent Publication No. 45 −
No. 14039, Japanese Patent Application Laid-Open No. 48-27736, etc., and it has been widely put into practical use.

In general, thermal recording paper is produced by separately grinding and dispersing a basic colorless dye and a color developer into fine particles, then mixing the two and adding binders, fillers, sensitivity enhancers, lubricants, and other auxiliaries. The resulting coating liquid is applied to a support such as paper or film, and color recording is obtained through an instantaneous chemical reaction caused by heating. In this case, various hues can be obtained by selecting the type of colorless dye.

These thermosensitive recording papers are being applied to a wide range of fields, including measuring recorders in the medical and industrial fields, combiators, information communication terminals, facsimile machines, printers for electronic desk calculators, and ticket vending machines.

In recent years, thermal recording methods have become widespread and their uses have diversified, and emphasis has been placed on increasing recording speed and improving image quality, that is, increasing density in order to increase resolution. For this reason, the thermal energy of the thermal head of a recording device tends to become smaller and smaller, and for the thermal recording paper used for this,
It is required to have sufficient color development sensitivity to obtain clear color recording even with a small amount of heat.

In addition, because thermal recording paper functions as information recording paper, it is unavoidable that it comes into contact with human hands, but the hands and fingers of those who handle it are exposed to oils and fats contained in hair products and skin sweat that are used on a daily basis. Since oily substances such as corners are often attached, it can be said that there are many opportunities for thermosensitive recording paper to be contaminated by these oily substances. However, thermal recording paper generally does not have sufficient stability against these oily substances, and the colored image density in contaminated areas may decrease or even disappear, and if white areas become contaminated, discolored images may appear. A phenomenon of color development and shimmering can be seen. The cause of these problems is not fully understood, but the oily substance may partially dissolve the color-forming layer formed by fine particles of basic colorless dye and a color developer, or its color-forming reaction product to create a stable cine state. This is thought to be for the purpose of

1 for color developers for heat-sensitive recording paper, Japanese Patent Publication No. 45-i40
Many substances are described in various Ume literature including No. 39, but 1. i,4'-isoglopylidensyphenol (bisphenol A) has been most widely used in terms of quality stability, price, availability, etc. However, this bisphenol species had the disadvantage of a high thermal coloring temperature, which meant that it could not be adequately adapted to recording using minute amounts of thermal energy, and was prone to problems such as sticking.

In recent years, there has been a demand for faster speeds and improved image quality for thermal recording paper, and in response to this, the applicant has developed p-
Proposed heat-sensitive recording paper using benzyl hydroxybenzoate in combination with fluoran dye.
No. 193), it was revealed that high sensitivity with excellent dynamic color development can be easily achieved. However, with thermal recording paper that uses benzyl p-hydroxybenzoate as a color developer, the density of the image formed by heat application decreases over time, and crystals precipitate on the image surface. The purpose of the present invention is to provide excellent heat responsiveness, as well as to improve the stability of the image area against oily substances. It is an object of the present invention to provide a heat-sensitive recording paper having excellent stability of a colored image against adhesion of.

(Means for Solving the Problems) The above object was achieved by containing a naphthol derivative represented by the following general formula (1) or (11) as an organic color developer in the heat-sensitive coloring layer.

[However, in general formulas (1) and (1), X is -5O2
-Ordinary or -〇-R, gold, R is 1 carbon atom! 1
an alkyl group having 2 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, (however, A and B are a hydrogen atom, a halogen atom, a nido a group, a lower alkyl group, a lower alkoxy group, a cyano group, or a hydroxyl group) and A and B may be the same.

m and n may be integers of 0 to 3, and m = n. ). ] Specific examples of the organic color developer represented by general formula (1) or (1) used in the present invention are shown below.

H O-8O□-CH3 H O-8O□-CH3 H It goes without saying that these naphthol derivatives can be used alone as color developers, but they can also be used in accordance with the present invention depending on their use and required performance. Color developers or the conventionally used bisphenol As p+9'-(1
-methyl-n-hexylidene) diphenol, p-
Phenols or organic compounds such as tertiary-butylphenol, p-phenylphenol, p-hydroxybenzoic acid ester, novolak phenolic resin, 4-hydroxy-1-methylsulfonylbenzene, 4-hydroxy-1-butyloxysulfonylbenzene It is also possible to use it in combination with acids.

These naphthol derivatives are also used as pressure anticaprilants (
For example, fatty acid amide, ethylene bisamide, montan wax), sensitizers (for example, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p
-Tolyl carbonate, p-benzylbiphale), stabilizers (e.g. EVA, phthalic acid monoester metal salt, p-tert-butylbenzoic acid metal salt, nitrobenzoic acid metal salt) can also be used in combination.

Although the basic colorless dye used in the present invention is not particularly limited, triphenylmethane-based, fluoran-based, azaphthalide-based, fluorene-based dyes, etc. are preferable, and specific examples thereof are shown below.

Triphenylmethane-based a ico dye 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide [also known as crystal violet cloudy chthon] Fluoran-based leuco dye 3-diethylamino-6-methyl-7- Anilinofluorane 3-(N-ethyl-p-tolubuino)-6-methyl-
7-anilinofluoran 3-(N-ethyl-N-isoamyl)amino-6-methyl-7-anilinofluoran 3-diethylamino-6-methyl-7-(mouth.

p-dimethylanilino)fluoran 3-pyrrolidino 6-methyl-7-7nilinofluoran 3-piperidino 6-methyl-7-aniIJ/fluoran 3-(N-cyclohexyl-N-methylamine)-6-
Methyl-7-anilinofluorane 3-diethylamino-
7-(m-trifluoromethylanilino)fluoran 3-diptylamino-7-(n-chloroanilino)fluoran 3-diethylamino-6-methyl-cumylfluoran 6-diethylamino-6-methyl-fluoran 3-cyclohexylamino-6 -Chlorfluoran 6-diethylamino-7-(O-chloroanilino)fluoran 6-dinithylaminobenzo(-)-fluoran 3-(
a-diethylamino-2-ethoxyphenyl)-3-(
1-ethyl-2-methylindol-3-yl)-4-
azaphthalide 3-(,i-diethylamino-2-ethoxyphenyl)-1-(1-ethyl-2-methylindol-3-yl)-7-azaphthalide 3-(a-diethylamino-2-ethoxyphenyl)-3- (1-octyl-2-methylindol-3-yl)-4-azaphthalide 5- (4-N-cyclohexyl-N-methylamino-
2-methoxyphenyl)-3-(1-ethyl-2-methylindol-6-yl)-4-azaphthalide fluorene leuco dye 3,6.6'-tris(dimethylamino)spiro 3'-phthalide) 3.6.6'-tris(diethylamino)spiro[fluorene-9,3'-phthalide] These dyes can be used alone or in combination of two or more. In particular, in the present invention, 3
-diethylamino-6-methyl-7-anilinofluorane, 3-(N-cyclohexyl-N-methylamino)-
6-Methyl-7-anilinofluorane, 3-(N-ethyl-N-ynamyl)amino-6-methyl-7-anilinofluorane, 3-(4-diethylamino-2-ethoxyphenyl)-3- When (i-ethyl-2-methylindol-3-yl)-4-aza7thallide was used alone.

In this case, a thermosensitive recording paper with extremely high dynamic color density can be obtained.

Also, a mixture of 3-diethylamino-6-methyl-7-anilinofluorane and 3-(N-cyclohexyl-N-methylamine)-6-methyl-7-anilinofluorane is used as a basic dye. In this case, a thermosensitive recording paper having a significantly high dynamic coloring density and excellent oil resistance and storage stability can be obtained.

The organic color developer and basic colorless dye mentioned above can be prepared by ball milling,
The blood is atomized to a particle size of several microns or less using a grinder such as an attritor or sand grinder, or a suitable emulsifying device, and various additive materials are added depending on the purpose to make blood. This coating solution usually contains polyvinyl alcohol,
Modified polyvinyl alcohol, droxyethyl cellulose, methyl cellulose, starches, binders such as styrene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, styrene-butadiene copolymer, and kaolin, calcined kaolin, Inorganic or organic fillers such as diatomaceous earth, talc, titanium oxide, and aluminum hydroxide are added, but in addition to these, mold release agents such as fatty acid metal salts, lubricants such as waxes, and benzophenone-based and triazole-based ultraviolet absorbers are added. , water-resistant agents such as glyoxal.

Dispersants, antifoaming agents, p-tert-butylbenzoic acid metal salts, nitrobenzoic acid metal rings), etc. can be used.

The types and amounts of the color developer, basic colorless dye, and other various components used in the present invention are determined according to the required performance and recording suitability, and are not particularly limited, but usually the basic colorless dye 1 3 to 12 parts of color developer and 1 to 20 parts of filler are used, and the binder is 10 to 25 parts of the total solid content.
The desired heat-sensitive recording paper can be obtained by applying a coating liquid having the above composition to paper or various films.

(Function) The reason why the organic color developer of the present invention has excellent thermal responsiveness is considered to be as follows. Since this compound is a naphthol derivative having a sulfonic acid ester group or a hacarboxylic acid ester group in the molecule, the basic colorless dye has an extremely high melting dissolution diffusion rate and saturation solubility in this compound. As a result, upon heating, the organic color developer and the basic colorless dye instantly become compatible with each other to form a color-forming composition.

Moreover, the reason for the excellent oil resistance is thought to be due to the unique molecular structure of the above-mentioned organic color developer.

That is, the organic color developer of the present invention causes a thermal melting reaction with the basic colorless dye to form a metastable charge transfer complex, and a colored image is obtained. Because the chemical bonding force between the organic color developer of the present invention and the basic colorless dye in this coloring process is specifically strong, the bond is not broken even if seismic acid or oils and fats adhere to it, and the colored image is is considered stable.

(Effect of the invention) The effects of the present invention include the following points.

(1) Due to its excellent thermal response, clear high-density images can be obtained even in high-speed, high-density recording. (2) Colored images are stable against adhesion of hair products and oils. There is.

(3) The ground color is white, and there is very little discoloration of the ground color over time.

(Example) The present invention will be explained below using examples. Furthermore, during the explanation,
Parts indicate parts by weight.

[Example 1] Solution A (dye dispersion) Solution B (developer dispersion) The canned solution of the above composition was ground with an attritor to a particle size of 6 microns.

Next, the entire dispersion liquid is mixed in the proportions shown below to prepare a coating liquid.

The above coating solution 'k 50 g/m'' was applied to one side of the base paper at a coating amount of approximately 6.0 g/m' and dried, and the smoothness was 200 to 60 using these sheet lath-par calenders.
[Example 2] Liquid C (developer dispersion) The above C@ treated with attritor was used in place of Liquid B in Example 1. A thermosensitive recording paper was prepared in the same manner except for the following.

[Comparative Example 1] Liquid D (Developer Dispersion) A thermosensitive recording paper was prepared in the same manner as in Example 1 except that the above-mentioned Liquid D treated with an attritor was used instead of Liquid B.

[Comparative Example 2] Liquid E (Developer Dispersion) A thermosensitive recording paper was prepared in the same manner as in Example 1, except that the above-mentioned Liquid E, which had been subjected to attritor treatment, was used instead of Liquid B.

Table 1 summarizes the results of quality performance tests conducted on the thermal recording papers obtained in the above Examples and Comparative Examples.

Note i1) Static color density: Pressed against a hot plate heated to 105°C for 5 seconds at a pressure of 10 g/-, and measured the developed color using a Macbeth densitometer (RD-514° using an amber filter. The same applies hereinafter).

Note (2) Dynamic color density; ROHMIK - Thermal printing tester T) Using IP 8050, the image*density recorded at an applied voltage of 16.5 v and a pulse width of 1.00 milliseconds was measured using a Macbeth densitometer.

Note (3) Oil resistance: Drop castor oil onto the colored area dynamically printed using the method in Note (2), wipe it off with a filter paper after 10 seconds, leave it at room temperature for 6 days, and then adjust the color density. Measured with a Macbeth densitometer.

The survival rate is calculated using the formula below.

Note (4) Ground color: Measure the uncolored area with a Macbeth densitometer.

Note (5) Moisture resistance;
Ground color density after standing for 4 hours Note (6) Heat resistance: Ground color density after standing for 24 hours under high temperature dry conditions at 60°C.

Claims (1)

[Claims] (1) In a heat-sensitive recording paper having a heat-sensitive coloring layer containing a basic colorless dye that is usually colorless or light-colored and an organic color developer, the organic color developer is expressed by the following general formula (I) or (II).
A thermosensitive recording paper characterized by containing a naphthol derivative represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) [However, in general formulas (I) and (II), X is -SO
＿2-R or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, where R is an alkyl group with 1 to 12 carbon atoms, a cycloalkyl group with 5 to 10 carbon atoms, ▲There are mathematical formulas, chemical formulas, tables, etc. There are ▼, ▲mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, A and B represent hydrogen atoms, halogen atoms, nitro groups, lower alkyl groups, lower alkoxy groups, cyano groups, or hydroxyl groups, and B may be the same. m and n are integers of 0 to 3, and m=n.). ]