JPH02215584A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material with high sensitivity and superior running properties by incorporating calcium carbonate having a platy crystal form with a specific average particle diameter. CONSTITUTION:A color former, a color developer, and a hot melt substance are dispersed in a water-soluble binder. A compound having a solubility of 5wt.% or more in a 25 deg.C water is preferable. As the color former for use, a triarylmethane compound, a diphenylmethane compound, a xanthene compound, a thiazine compound, and a spiropyrane compound are exemplified. As the color developer for use, a phenolic compound, a salicylic acid derivative, and the polyvalent metallic salt thereof are preferably used. A pigment for use is required to be a calcium carbonate having a platy crystal form with an average particle diameter of 0.1 - 5.0mum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having high sensitivity and excellent facsimile running properties.

(Prior art) Recording materials using an electron-donating dye precursor (hereinafter referred to as a color former) and an electron-accepting compound (hereinafter referred to as a color developer) include pressure-sensitive recording paper, heat-sensitive recording paper, photosensitive pressure-sensitive It is well known as recording paper and electrically conductive thermal recording paper.

For example, British Patent No. 2140449, US Patent No. 44800
No. 52, No. 4436920, Special Publication No. 60-23922
No., JP-A-57-179836, JP-A No. 60-12355
It is described in detail in No. 6, No. 60-123557, etc.

In recent years, there has been a strong demand for high-sensitivity heat-sensitive recording materials, and various studies have been carried out, but so far nothing that is considered to be sufficient has been developed. There is a demand for heat-sensitive recording materials with high sensitivity and excellent running properties.

(Object of the Invention) An object of the present invention is to provide a heat-sensitive recording material with high sensitivity and excellent running properties.

(Structure of the Invention) The object of the present invention has been achieved by a heat-sensitive recording material characterized by containing calcium carbonate having a plate-shaped crystal morphology with an average particle diameter of 0.1 μm to 5.0 μm.

In the present invention, the color forming agent, developer, and thermofusible substance are dispersed in a water-soluble binder. Preferable compounds include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, starch 1jl (including modified starch), gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, and carboxy-modified polyvinyl alcohol. , polyacrylamide, and saponified products of vinyl acetate-polyacrylic acid copolymers.

These binders are used not only for dispersion but also for the purpose of improving coating film strength. A synthetic polymer latex binder such as acid methyl butadiene copolymer or polyvinylidene chloride may also be used. Alternatively, a similar binder can be used for the undercoat layer as well.

Examples of the coloring agent used in the present invention include tri7lylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, and spiropyran compounds. A specific example is JP-A-55-22725.
Examples include those described in No. 3. Although some of these are disclosed, tri7lylmethane compounds include 3,3-bis(p-dimethyl7minophenyl)-6-
Dimethyl 7-minophthalide, 3,3-bis(p-dimethyl 7-minophenyl) phthalide, 3-(p-dimethyl 7-minophenyl)-3-(1,3 dimethylindol-3-yl) phthalide, 3-(p-dimethyl 7-minophthalide) minophenyl)-
3-(2-methylindol-3-yl) phthalide,
etc., and as a diphenylmethane compound, 4.4
'-bis-dimethyl 7-minobenzhydrin benzyl ether, tohalophenyl leukoolamine, N-2,4
, 5-tric-O-lophenyl-O-ico-olamine, etc.
As xanthine compounds, O-damine-8-7 dilinolactam, O-damine-(p-nitrino)lactam,
2-(dibenzylamino) fluorane, 2-7 dilino 3-methyl-6-ethyl 7minofluorane, 2-7
Nilino 3-methyl-6-cyptyl 7minofluorane,
2-7 Nilino 3-methyl-6-toethyl-isoamyl 7minofluorane, 2-7 Nilino 3-methyl-6-
Domethyl-N-cyclohexyl 7minofluorane, 2-
7 Nilino 3-ri0-6-ethylaminofluorane, 2-7 Nilino 3-methyl-6-toethyl isobutyl 7 Minofluorane, 2-7 Nilino 6 dibutyl 7 Minofluorane, 2-7 Nilino 3-methyl-6- Domethyltetrahydrofurfuryl 7minofluorane, 2-
7nilino 3-methyl-6-piperidinoaminofluorane, 2-(o-rioo7nilino)-6-dinithylaminofluorane, 2-(3,4-dichloroanilino)-6
- dinityl 7minofluorane, etc., and thiazine compounds include benzoylleucon methylene blue, p
-Nitrobenzylleucomethylene blue, etc. Subi0-based compounds include 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran 3,3'-dic00-spiO-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-Methyl-naphtho-(3-methoxy-benzo)-spiropyran, 3-propyl-spiro-
Examples include dibenzobilane.

The color developer used in the present invention is preferably a phenolic compound, a salicylic acid derivative, or a polyvalent metal salt thereof.

To give some examples of these, phenolic compounds include 2,2'-bis(4-hydroxyphenyl)propane, 4-t-butylphenol, 4-phenylphenol, 4-human oxydiphenoxide, 1 , 1°-bis(3-chloro-4-hydroxyphenyl)cyclohexane, 1,1°-bis(4-human 0xyphenyl)cyclohexane, 1.1°-bis(3-rioo-4-hydroxyphenyl)- 2-ethylbutane, L 4'-5ee-
inoctylidene diphenol, 4,4″-5ec-butylidene diphenol, 4-tert-octylphenol, 4-ρ-methylphenylphenol, 4,4′-
Examples include methylcyclohexylidenephenol, 4°4°-inpentylidenephenol, and benzyl p-hydroxybenzoate. Salicylic acid derivatives include 4-pentadecylsalicylic acid and 3.5-di(α-methylbenzyl).
Salicylic acid, 3.5-di(tar-octyl)salicylic acid, 5-octadecylsalicylic acid, 5-α-(p-α-
methylbenzylphenyl) ethylsalicylic acid%3-(
X-Methylbenzyl-5-ter-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-Schiff0hexyloxysalicylic acid, 4-
Examples include decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-pentadecyloxysalicylic acid, 4-octadecyloxysalicylic acid, etc., and their zinc, aluminum, calcium, copper, and lead salts. It is preferable to use these color developers in an amount of 50 to 800% by weight of the color former.
More preferably, it is 100 to 500% by weight. 50
If the amount is less than 80% by weight, the color development will not be sufficient, and even if 800% by weight is added in the breath, no improvement can be expected, which is not preferable.

In the heat-sensitive recording material of the present invention, a heat-fusible substance can be contained in the heat-sensitive coloring layer in order to improve its heat responsiveness. Examples of preferred thermofusible substances include benzyl ρ-benzyloxybenzoate, β-naphthyl-benzyl ether, stearamide, stearyl urea, p-benzylbiphenyl, di(2-methylphenoxy) ethane,
Di(2-methoxyphenoxy)ethane, β-naphthol-(p-methylbenzyl) ether, α-naphthylbenzyl-thyl, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p- Isopropylphenyl ether, 1,4-butanediol-ρ
~tart-octylphenyl ether, 1-phenoxy-2-(4-ethylphenoxy) ethane, 1-phenoxy-2-(4-ri00phenoxy) ethane, 1,
Examples include 4-butanediol phenyl ether and diethylene glycol-bis(4-methoxyphenyl) ether.

The thermofusible substances may be used alone or in combination,
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 electron-accepting compound.

The pigment used in the present invention has an average particle size of 0.1 μm to 5.0 μm.
It is necessary that the calcium carbonate has a plate-like crystal form of μm, and other pigments may be used in combination.
It is preferable that the calcium carbonate is 0.5 s/ffr or more. The average particle diameter here is determined by measuring the length of the longest part using a photographic image taken with a scanning electron microscope at a magnification of 20,000 times, calculating the average value of n = 5 o o, and calculating the average particle diameter. did.

Furthermore, metal soap, wax, surfactant, antistatic agent, ultraviolet absorber, antifoaming agent, conductive agent, glory dye, etc. may be added as necessary.

As the metal soap, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate, aluminum stearate, and the like.

As the wax, paraffin wax, microcrystalline wax, carnauba wax, methio-O-Ruste 707mide, polyethylene wax, polystyrene wax, fatty acid 7mide wax, etc. may be used alone or in combination.

As the surfactant, a sulfosuccinic acid-based alkali metal salt and a fluorine-containing surfactant are used.

Further, it is preferable to add a decoloring inhibitor to the heat-sensitive color forming layer in order to prevent decoloring of the image-printed area and to make the generated image more robust. Phenol compounds, especially hindered phenol compounds, are effective as anti-fading agents, such as 1
．． 1.3-tris(2-methyl-4-hydroxy-te
rt-butylphenyl) butane, ? , 1.31 squirrel (
2-ethyl-4-hydroxy-5-tart-butylphenyl)butane, l, 1,3-tris(3,5-di-t)
*rt-butyl-4-humanOxyphenyl)butane, 1
．． 1.3-tris(2-methyl-4-hydroxy-5-
tert-butylphenyl) propane, 2.2'-methylene-bis(6-tert-butyl-4-methylphenol), 2°2°-methylene-bis-($-tart
-butyl-4-ethylphenol), 4,4'-butylidene-bis(5-tert-butyl-3-methylphenol), 4,4'-thio-bis-(3-methyl-5-t
The amount of such phenolic compounds used is preferably 1 to 200% by weight, more preferably 5 to 50% by weight, based on the color developer.

After each of these materials is mixed, it is applied to a support.

Paper, synthetic paper, various bases, etc. are used as the support, but in order to obtain high smoothness, it is preferable to provide an undercoat layer on the support in advance. Average grain prognosis 0.1 μm ~ 5.0
Calcium carbonate having a micron platelet crystal morphology can be used.

The coated heat-sensitive recording material is dried and subjected to a process such as a calender before being used.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited only to the Examples below.

(Example-1) (Preparation of undercoated paper) Calcined kaolin (manufactured by Engelhardt Co., Ltd.; 7Ncilex 9)
3) 80 g was dispersed with a 0.5% sodium hexametaphosphate aqueous solution 1609 using a homogenizer to obtain a pigment dispersion. Styrene-butadiene latex (manufactured by Sumitomo Naugatax Co., Ltd.; 5N307, solid content concentration 48%) 169 and polyvinyl alcohol (manufactured by Kuraray Co., Ltd.; PVA-117) 10% aqueous solution 249 were added to the pigment dispersion to form an undercoat. A coating liquid was obtained. The above coating liquid for undercoat was applied to high quality paper at 50 s/rrf to a coating density of 89/rd and dried to prepare underfoot paper.

(Preparation and coating of coating liquid for heat-sensitive coloring layer) 3-dibutylamino-6-methyl-7-7nilinofluorane 209
Polyvinyl alcohol (5t, manufactured by Co., Ltd.; pVA-10)
5) Dispersion was carried out with a 5% aqueous solution 1009 in a ball mill for 24 to 48 hours to obtain a dispersion having an average particle size of 1.0 μm.

Furthermore, bisphenol A409 and naphthylbenzyl ether 409 were added to polyvinyl alcohol (manufactured by Kuraray Co., Ltd.; PV
A-105) 24-48 with 10% aqueous solution 4009
The mixture was dispersed in a ball mill for a time to obtain a dispersion having an average particle size of 1.0 μm. Also, calcium carbonate (manufactured by Chichibu Lime Industry Co., Ltd., light calcium carbonate type 03. particle size 0.3 μm) 809
160g of 0.5% aqueous solution of sodium hexametaphosphate
The mixture was dispersed using a homogenizer to obtain a pigment dispersion.

The dispersion obtained as described above was mixed, and 21% zinc stearate emulsion 509 was further added to obtain a coating solution for thermal paper, and a dry coating amount of 7% was applied to the undercoated paper.
The heat-sensitive recording material of the present invention was obtained by coating the film with a wire bar so as to give a 97-glycanth film and drying it in an oven at 50°C.

[Example-2] Calcium carbonate (manufactured by Chichibu Lime Industry Co., Ltd., light calcium carbonate type 03) used in the thermosensitive coloring layer in Example-1
) A thermosensitive recording material was obtained in the same manner as in Example 1, except that calcium carbonate (manufactured by Chichibu Lime Industries Co., Ltd., light calcium carbonate type 07, particle size 0.7 μm) was used.

(Comparative Example-1) The calcium carbonate used in the thermosensitive coloring layer in Example-1 was replaced with calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd.).

A heat-sensitive recording material was obtained in the same manner as in Example-1 except that the material was changed to PC (spindle-shaped).

(Comparative Example-2) The calcium carbonate used in the thermosensitive coloring layer in Example-1 was replaced with calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd.).

Example except that it was changed to Brilliant-15 (cubic)
A thermosensitive recording material was obtained in the same manner as in Example 1.

(Comparative Example-3) Example-1 except that calcined kaolin (manufactured by Engelhardt; 7Ncilex 93 oil absorption 180-/1009) was used instead of the calcium carbonate used in the thermosensitive coloring layer in Example-1. A heat-sensitive recording material prepared in the same manner as in Example 1 was obtained.

(Comparative Example-4) Implemented except that calcium carbonate (manufactured by Chichibu Lime Industry Co., Ltd.; light calcium carbonate 70.3 powder type particle size 10 μm) was used instead of the calcium carbonate used in the thermosensitive coloring layer in Example-1. A thermosensitive recording material was obtained in the same manner as in Example-1.

The heat-sensitive recording paper obtained in the above manner was surface-treated with a low-pressure calender, and the thermal head manufactured by Kyocera (LT) was
-216-88PDl) and 9 to 100 just before the head
In a thermal printing experiment equipment with a 1cIi pressure roll,
While using a pressure roll under the conditions of a head voltage of 24cm and a pulse cycle of 10m5, the pulse intensity was set to 0.8.1.0.
1.2, and check the print density using Macbeth reflection densitometer R.
Measured with D-918.

The running performance was measured by copying the Image Electronics Engineers of Japan test chart N11.3 using Fujitsu's high-speed facsimile FF-2000, and checking the stackability and sticking of the printed sample.
Head staining was evaluated based on the following criteria.

(accumulation) 0: Good stackability when stacking 100 sheets.

Of the 61,100 sheets that were stacked, less than 5 sheets were not stacked properly.

x; Out of 100 sheets stacked, 6 or more sheets were not stacked properly.

(sticking) ○: No occurrence of sticking was observed.

Δ; 2 to 3 areas of overexposure (due to stick-slip,
Although there are some areas that are not printed, there is no shrinkage of the print.

×: There are many overexposed areas, and the printed characters are also shrunken.

(head dirty) 0: No head stains were observed even after printing 100 sheets.

Δ: Head stains are observed after printing 100 sheets, but do not affect the printed surface.

X: After printing 100 sheets, the head is so dirty that it scratches the printing surface and causes printing problems.

The evaluation results for the above evaluation items are shown in Table 1.

As shown in Table 1, it can be seen that the present invention provides a heat-sensitive recording material with high sensitivity and excellent running properties.

that's all

Claims (1)

[Claims] A heat-sensitive recording material characterized by containing calcium carbonate having a plate-like crystal morphology with an average particle diameter of 0.1 μm to 5.0 μm.