JPH0316787A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To maintain sensitivity high, to improve whiteness and to prevent fog by employing specific colorant which is thermally mixed and melted with thermally fusible substance having a low melting point as electron donative dye precursor in a coloring layer. CONSTITUTION:A coloring layer contains 2-anilino-3-methyl-6-dibutylaminofluoran as electron donative dye precursor and 2-anilino-3-methyl-6-dibutylaminofluoran thermally mixture melted with thermally fusible substance having a low melting point. Even if such a colorant and a sensitizer are mixture melted integrally, the mixture is easily crystallized. Thus, whiteness of a recording material is not remarkably reduced, and a heat sensitive recording material which exhibits satisfactory printing density, small fog and satisfactory heat resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a heat-sensitive recording material, and more particularly, a color forming layer containing an electron-donating dye precursor and an electron-accepting compound is formed on a support. Regarding the heat-sensitive recording material provided.

(Prior art ff) Regarding thermal recording, many methods have been known for a long time. For example, recording materials using an electron-donating dye precursor and an electron-accepting compound are disclosed in Japanese Patent Publications No. 14039-1983, Japanese Patent Publication No. 4160-43-1974, and the like. In recent years, there has been much research into increasing the sensitivity of heat-sensitive recording materials in order to increase the speed and energy of heat-sensitive recording systems. A method for further improving the recording sensitivity is disclosed in Japanese Patent Application Laid-Open No. 5-3-4-8.
As disclosed in No. 751, a method has been proposed in which at least one of an electron-donating dye precursor or an electron-accepting compound and a low-melting-point thermofusible substance are mixed and integrated. However, by blending and integrating an electron-donating dye precursor and a low-melting-point thermofusible substance, although the recording sensitivity is increased, the whiteness of the recording material is significantly reduced.
Problems such as fogging may occur depending on the storage conditions. (Objective of the Invention) An object of the present invention is to provide a heat-sensitive recording material that is highly sensitive, has high whiteness, and has little fog. (Structure of the Invention) An object of the present invention is to provide an electron-donating dye precursor (hereinafter referred to as a color former) and an electron-accepting compound (hereinafter referred to as a color developer) that develops a color by being brought into contact with the electron-donating dye precursor. In a heat-sensitive recording material containing 2-anilino-3-methyl- as an electron-donating dye precursor in the coloring layer,
6-diptylaminofluorane and 2-anilino-3-methyl-6-diptylaminofluorane is heated and mixed with a low melting point thermofusible substance (hereinafter referred to as a sensitizer). This was achieved through a heat-sensitive recording material family characterized by the fact that it contains By blending and integrating the color former and the sensitizer, the recording sensitivity is increased, but there are problems such as a marked decrease in the whiteness of the recording material and fogging depending on the storage conditions. After intensive investigation into this problem, we found that by blending and fusing the color former with the powder coating, the color former becomes more likely to take an amorphous state, resulting in a significant decrease in the whiteness of the recording material. However, it has been discovered that the 2-anilino-3-methyl-6-diptylaminofluorane used in the present invention tends to crystallize even when the sensitizer is mixed and integrated. Therefore, a heat-sensitive recording material containing 2-7 dilino-3-methyl-6-diptylaminofluorane heated and mixed with a sensitizer has high sensitivity, high whiteness, and no fog. It has been discovered that this does not occur, and it is possible to achieve this objective, leading to the present invention. The method of heating and blending 2-anilino-3-methyl-6-diptylaminofluorane with a sensitizer is not particularly limited, but includes, for example, the method disclosed in JP-A-53-48751.

In order to obtain the effects of the present invention, it is necessary that 2-anilino-3-methyl-6-diptylaminofluorane accounts for 50% by weight or more of the total amount of color former used. Under the conditions described above, other color formers can be used in combination.

Examples of the coloring agent include tri7lylmethane compounds, diphenylmethane compounds, xanthene compounds, thi7dine compounds, and spiopyran compounds. Specific examples include those described in JP-A No. 5-2-27253. To disclose some of these, tri7lylmethane compounds include 3.3-bis(p-dimethyl7minophenyl)-6-dimethyl7minophthalide, 3.3-bis(p-dimethyl7minophenyl) Phthalide, 3-(p-dimethyl7minophenyl)-3-(1.3-dimethylindol-3-yl)
Phthalide. 3-(p-dimethyl7minophenyl)-
3-12-methylindol-3-yl》phthalide, etc., and diphenylmethane compounds include 4.4'
-Bis-dimethyl 7-minobenzhydrin benzyl ether, Makoto-haO phenyl-oicoolamine, N-2.
4. There are 5-trichloro-O-phenyl-0-ico-olamine, etc., and xanthene-based compounds include 0-damine-8
- 7nilinolactam, rhodamine-《p-nitrino》
Lactam% 2-(dibenzyl 7mino) Fluorane, 2-anilino-3-methyl-6-diethyl 7minofluorane, 2-anilino-3-methyl-6-M-ethyl-iso7mil 7minofluorane, 2-anilino- 3-
Methyl-6-N-methyl-bound-cyclohexylaminofluorane, 2-anilino-3-chloro-6-diethyl 7
Minofluorane, 2-anilino-3-methyl-6-N-
Ethyl-H-isobutyl 7minofluorane, 2-anilino-6-diptylaminofluorane, 2-anilino-3
-Methyl-6-N-methyl-κ-tetrahydrofurfurylmethyl7minofluorane, 2-7dilino3-methyl-6-biberidino7minofluorane, 2-(O-chloro0
7nilino》-6-diethyl 7minofluorane, 2-(3
．． 4-Dichloro7nilino》-6-diethyl7minofluorane, 2-anilino-3-methyl-6-1-ethyl M
- n-hexyl 7minofluorane, 2-anilino-3
-Methyl-6-N-ethyl-H- γ-ethoxypyl 7 minofluorane, 2-anilino-3-methyl-6-κ-methyl-axis γ-ethoxypropyl 7 minofluorane, 2-anilino-3-methyl-6 Ikhan-Ethiru N
-1-Methoxyprobyl 7-minofluorane, 2-7-dilino-3-methyl-6-dipentyl-7-minofluorane, etc., and thi7dine-based compounds include penzoyl O-icon methylene blue, p-nitropenzylleucomethylene blue, etc. , Spi0 type compounds include 3-methyl-spiro dinaphthopyran, 3-ethyl-spiro dinaphthopyran 3.3゜-diku-aO-subio-dinaphthopyran, 3-penzyl-spiro-dinaphthopyran, 3-methylnaphthol (3-methoxybenzo) -Spiriovirane, 3-probilusvirodibenzopyran, etc. Examples of sensitizers used in the present invention include benzyl p-penzyloxybenzoate, β-naphthylbenzyl ether, stearin M7mide, stearyl urea% p-pendylbiphenyl, diC2-methylphenoxyethane, <<2-methoxyphenoxy>>ethane, β-naphthol-
<p-Methylbenzyl> ether, α-naphthylbenzyl ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-isopropylene O
bilphenyl ether, 1,4-butanediol p-
tert-octylphenyl ether, 1-phenoxy-2-<<4-ethylphenoxy>> ethane, 1-phenoxy-2-C4-kOOphenoxy)ethane, 1.4-
Butanediol phenyl ether, diethylene glycol bis《4-methoxyphenyl》ether, 4'
-methoxyphenyl-4-methylbenzyl ether, 4
1-methylphenyl-4-methoxybenzyl ether,
4-Methoxyphenyl-4-chlorobenzyl ether, 41-ethoxyphenyl-4-chlorobenzyl ether, 491-methoxyphenyl-4-methoxybenzyl ether, di<4-methoxyphenoxy>ethane, 1.3
-Di《4-methoxyphenoxy》propane, 1.2-
Bis(4-methoxyphenoxy)propane, 1.2-
Bis-(4-ethoxyphenoxy)propane, 1-(4
-methoxyphenoxy)-2-(4-ethoxyphenoxy)propane. 1-(4-ethoxyphenoxy)-2-
(4-methoxyphenoxy)propane. 1.2-bis(2-methoxyphenoxy)propane. 1-(4-methoxyphenoxy)-2-(2-methoxyphenoxy)propane. 1-(4-methoxyphenoxy)-2-phenoxypropane. etc. The sensitizers may be used alone or in combination, and in order to obtain sufficient thermal responsiveness, it is preferably used in an amount of 10 to 200% by weight, more preferably 20 to 150% by weight, based on the color developer. %. In addition, other than the sensitizer to be mixed with the color former may be added. Next, a typical method for producing a heat-sensitive coloring layer of the present invention will be described. The coloring agent, developer, and sensitizer mixed with the sensitizing agent are generally dispersed together with an aqueous solution of a water-soluble polymer such as polyvinyl alcohol using a ball mill, sand mill, etc. to a particle size of 0 or less.

After dispersion, these dispersions are mixed, and if necessary, pigments, surfactants, binders, metal soaps, waxes, antioxidants, ultraviolet absorbers, etc. are added to prepare a sensitive JIFgI liquid. The obtained heat-sensitive coating liquid is coated on high-quality paper, high-quality paper with an undercoat layer,
After being coated and dried on synthetic paper, plastic film, etc., smoothness is imparted by calendering, resulting in the desired heat-sensitive recording material. Also, JP-A-60-255478
A protective layer as described in et al. may be applied.

Furthermore, if necessary, a back coat layer may be provided on the opposite side of the support of the heat-sensitive recording material from the heat-sensitive recording layer. As the back coat layer, any material known as a back coat layer for heat-sensitive recording materials can be used.

As the darkening agent used in the present invention, phenolic compounds or salicylic acid derivatives and polyvalent metal salts thereof are preferred.
To give some examples of these, phenolic compounds include 2.2''-bis(4-hydrooxyphenyl)propane, 4-t-butylphenol, 4-phenylphenol, 4-hydrooxydiphenoxide, 1,1゜-bis《3-chloroo-4-hydrooxyphenylene》 cyclohexane, 1゜-bis(4-hydrooxyphenyl)cyclohexane, 1.1゜bis(3-chlorohexane) -4-Hydooxyphenyl)-2-ethylbutane, 4.4°-se
c-yneoctylidene diphenol, 4. -sec-butylidene diphenol, 4-tart-ocrphenol, 4-p-methylphenylphenol, 4.4°-methylcyclohexylidenephenol, 4,V-isopentylidenephenol, benzyl p-hydroxybenzoate, etc. be. Examples of salicylic acid derivatives include 4-pentadecylsalicylic acid, 3,5-di(α-methylbenzyl)salicylic acid, 3,5-di(tar-octyl)salicylic acid, and 5-di(α-methylbenzyl)salicylic acid.
-octadecylsalicylic acid, 5-α-(p-α-methylbenzylphenyl) ethylsalicylic acid, 3-α-methylbenzyl-5-tar-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-cyclohexyl Oxysalicylic acid, 4-decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-
These include pentadecyloxysalicylic acid, 4-octadecyloxysalicylic acid, etc., and their zinc, 7-luminium, calcium, copper, and lead salts. These fog coloring agents are preferably used in an amount of 50 to 800% by weight, more preferably 100 to 500% by weight of the color former. If it is less than 50% by weight, the color development will not be sufficient, and even if it is added in an amount of 800% by weight or more, no further effect can be expected, which is not preferable. The binder used in the present invention includes polyvinyl 7 alcohol (including modified polyvinyl alcohols such as carpoxy-modified, itaconic acid-modified, maleic acid-modified, and silica-modified polyvinyl alcohols),
Methyl cellulose, carboxymethyl cellulose, starch cheeks (including modified starch), gelatin, 7rabi 7 gum, casein, styrene-maleic anhydride copolymer hydrolyzate, polyacrylic 7mide, vinyl acetate polyester Examples include saponified products of acrylic acid copolymers. These binders are used not only when dispersing, but also when dispersing! 1ll [Used for the purpose of improving strength, but for this purpose, styrene-butadiene copolymer, vinyl acetate copolymer, 7-crinitrile-butadiene copolymer, 7-methyl acrylate-butadiene copolymer It is also possible to use a synthetic polymer latex binder such as polyvinylidene chloride or polyvinylidene chloride.
Further, if necessary, a suitable crosslinking agent for the binder may be added depending on the strength of the binder. As pigments, calcium carbonate, barium sulfate, lithopone, quartzite, kaolin, silica, amorphous silica, etc. are used. As the metal soap, metal salts of fatty acids are used, such as zinc stearate, calcium stearate, and aluminum stearate. As the wax, paraffin wax, microcrystalline wax, carnauba wax, 'methy0-ruste 7C17 mido, polyethylene wax, polystyrene wax, fatty acid 7 mido wax, etc. may be used alone or in combination. Furthermore, surfactants, antistatic agents, ultraviolet absorbers, antioxidants, antifoaming agents, conductive agents, fluorescent dyes, coloring dyes, etc. may be added as necessary. Furthermore, an anti-fading agent may be added to the heat-sensitive coloring layer in order to prevent the image-printed area from fading and to make the generated image more robust. Phenol compounds, especially hindered phenol compounds, are effective as anti-fading agents. The amount of the phenolic compound to be used is preferably 1 to 200% by weight, more preferably 5 to 50% by weight based on the electron accepting compound. The present invention will be explained in detail with reference to Examples below, but the present invention is not limited to the Examples. (Example-1) 2-anilino-3-methyl-6-diptylaminofluorane 20G and β-naphthylbenzyl ether 409
Heat to 200℃ and mix. Cool this mixture,
After solidification, polyvinyl 7 alcohol (K5L/manufactured by Co., Ltd.; PVA
-105) Dispersed with 5% aqueous solution 3009 in a ball mill for 24 hours to obtain a dispersion with an average particle size of 1.0 μm. Further, bisphenol A409 was dispersed in a Pall mill for 24 hours with a 5% aqueous solution of polyvinyl 7 lefur (manufactured by Kuraray Co., Ltd.; PVA-105) 2009 to obtain a dispersion with an average grain size of 1.0 μm. Calcium carbonate (Shiraishi Kogyo; Univer 70) 809 with 0.5% sodium hexametaphosphate
A pigment dispersion was obtained by dispersing with 160 g of an aqueous solution using a homogenizer. Mix the dispersion obtained as above,
Further, 21% of zinc stearate emulsion 509 was added to obtain a coating solution for thermal paper, which was coated on a piece of high-quality paper with a basis weight of 509 liters using a wire bar so that the dry coating amount was Ss/1, and then heated at 50°C. The heat-sensitive recording material of the present invention was obtained by drying in an oven. (Example-2) In Example-1, β-naphthylbenzyl ether 40
A thermal recording material was obtained in the same manner as in Example 1 except that rosebenzylbiphenyl 409 was used instead of 9. (Example-3) In Example-1, β-naphthylbenzyl ether 40
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 1,←butanediol diphenyl ether was used instead of 9. (Comparative Example-1) In Example-1, 2-anilino-3-methyl-6-diethyl-7minofluorane 209 was used instead of 2-anilino-3-methyl-6-diptylaminofluorane 209.
A thermosensitive recording material was obtained in the same manner as in Example-1 except that .

(Comparative Example-2) In Example-1, instead of 2-anilino-3-methyl-6-diptylaminofluorane 209, 2-anilino-3-methyl-8-N-ethyl-N-iso7mil7 A thermal recording material was obtained in the same manner as in Example-1 except that Minofluorane 209 was used.

(Comparative Example-3) In Example-1, 2-anilino-3-methyl-8-N-methyl-N-cyclohexyl 7 was used instead of 2-anilino-3-methyl-6-diptylaminofluorane 209. A heat-sensitive recording material was obtained in the same manner as in Example-1 except that Minofluorane 209 was used. (Comparative Example-4) 2-anilino-3-methyl-6-diptylaminofluorane 209 was mixed with polyvinyl alcohol (K5L/manufactured by P
VA-105) Dispersed with 5% aqueous solution 1009 in a ball mill for 24 hours, with an average particle size of 1. A dispersion of Oam was obtained. Furthermore, bisphenol A409 and β-naphthylbenzyl ether 409 were added to 24 g of a 5% aqueous solution of polyvinyl 7 alcohol (manufactured by Kuraray Co., Ltd.; Pv^-105).
Dispersed in a ball mill for an hour, with an average particle size of 1. A dispersion of Gum was obtained. Calcium carbonate (manufactured by Shiraishi Kogyo; Unibar 70
) 809 was dispersed with a 0.5% sodium hexametaphosphate aqueous solution 1609 using a homogenizer to obtain a pigment dispersion.

The separation solution obtained as described above was mixed and 21% zinc stearate emulsion 509 was further added to obtain a coating solution for thermal paper.
It was coated with a wire bar to give a coating density of 97% and dried in an oven at 50°C to obtain a heat-sensitive recording material.

The thermal recording paper obtained as described above was surface-treated with a low-pressure calender, and then heated using a thermal headl' (K) manufactured by Kyocera ■.
LT-216-8MPDI) and 100 just before the head
In a thermal printing experiment apparatus having a pressure roller of kglal, the pulse width was changed to Q.kglal while using a pressure roll under the conditions of a head voltage of 24v and a pulse cycle of 10-3. Printing was performed in 5 ms, and the print vagueness and white area leakage were measured using a Macbeth reflection vagueness meter RO-918. Heat resistance is 60℃3
The density of the white background area when stored in an environment of 0RH for 24 hours was measured using a Macbeth reflection A meter RD-918.

The results are shown in Table 1. Table 1 Print density Anti-fog Examples Examples Examples Examples Comparative examples Comparative examples Comparative examples Comparative examples. 22. 25. 20. 23. 25 1.18 0.98 0.08 0.09 0.08 0.36 0.32 0. 30 0.07 0.10 0.11 0.11 0.86 0.53 0.44 0.09 As shown in Table 1, the insensitive recording material according to the present invention has good print density even at low energy. It can also be seen that the material has low fog and good heat resistance.

Claims (1)

[Claims] In a heat-sensitive recording material containing as a product component an electron-donating dye precursor and an electron-accepting compound that develops color upon contact with the electron-donating dye precursor, 2-anilino- Contains 3-methyl-6-diptylaminofluorane, and also contains 2-anilino-3-methyl-6-diptylaminofluorane heated and mixed with a low melting point thermofusible substance. A heat-sensitive recording material characterized by: