JP3115388B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material,
More specifically, the present invention relates to a heat-sensitive recording material having high sensitivity and excellent image clarity due to improvement in dispersibility and liquid stability of a dispersion used as a heat-sensitive coating solution.

[0002]

2. Description of the Related 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 developer) include pressure-sensitive recording paper, heat-sensitive recording paper, and photosensitive pressure-sensitive recording paper. It is well known as a recording paper or a current-carrying thermal recording paper. For example, British Patent No. 2140449, U.S. Pat.
No., JP-B-60-23922, JP-A-57-179836, JP-A-60-1235
No. 56 and No. 60-123557 are described in detail. In recent years, there has been a strong demand for high-sensitivity heat-sensitive recording materials, and various studies have been made, but they have not yet been sufficiently developed.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material having high sensitivity and excellent image clarity.

[0004]

An object of the present invention is to provide a pigment.
This was achieved by using a heat-sensitive recording material containing calcium carbonate having an oil absorption of 100 ml / 100 g or more and a polystyrene sulfonate as a dispersing aid for the calcium carbonate in the heat-sensitive coloring layer. The above-mentioned calcium carbonate is not limited to use alone, but can be used in combination with other inorganic oil-absorbing substances (silica, kaolin, talc, etc.).

[0005] The oil absorption referred to in the present invention is a value measured by the Ogura method. When using an oil having a high material as described above in the thermosensitive color developing layer, sodium hexametaphosphate has been widely used as a dispersing aid prior pigments, maleic acid copolymer sodium salt, such as carboxylic acid copolymer It is difficult for a dispersion aid to impart sufficient dispersion stability.

[0006] Used as a dispersion aid in the present invention
The polystyrene sulfonate is used in an amount of 0.5 to 3 based on the pigment.
% By weight, preferably 1-2% by weight. Like this
The dispersed calcium carbonate dispersion has a low viscosity and
Because of its high dispersion stability, it has excellent manufacturing suitability
It is.

In the present invention, the color former, the developer and the heat-fusible substance are dispersed in a water-soluble binder. The binder used in the present invention is 5% by weight based on 25 ° C. water. Compounds that dissolve as described above are preferable, and specifically,
Polyvinyl alcohol, methylcellulose, carboxymethylcellulose, starches (including modified starch), gelatin, gum arabic, casein, styrene
Examples include a maleic anhydride copolymer hydrolyzate, carboxy-modified polyvinyl alcohol, polyacrylamide, and a saponified vinyl acetate-polyacrylic acid copolymer.
These binders are used not only at the time of dispersion but also for the purpose of improving the strength of the coating film. For this purpose, styrene-butadiene copolymer, vinyl acetate copolymer, acrylonitrile-butadiene copolymer, A latex-based binder of a synthetic polymer such as vinylidene chloride may be used in combination. Alternatively, the same binder can be used for the undercoat layer.

The color former (leuco dye) used in the present invention is applied alone or as a mixture of two or more.
As such leuco dyes, those applied to this type of recording material are arbitrarily applied, for example, triphenylmethanephthalide, triallylmethane, fluoran,
Phenotidin, thioferoran, methine, rhodamine anilinolactam, rhodamine lactam,
Leuco compounds such as quinazoline, diazaxanthene and bislactone are preferably used. Examples of such compounds include, for example, those shown below. 3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6- Diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexialamino-6-chlorofluoran, 3-dimethyl amino-
5,7-dimethylfluoran, 3- (N-methyl-N-isoamylamino) -6-methyl-7-anilinofluoran, 3- (N-methyl-N-isobutylamino) -6-methyl-7 -Anilinofluoran, 3- (Np-tolyl-N-ethylamino) -6-methyl-7-
Anilinofluoran, 3- (N-methyl-N-amylamino)-
6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran,
3- (N-methyl-N-iso-propylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofur Oran, 3-diethylamino-7,8-benzfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3- Pyrrolidino-6-methyl-7-anilinofluoran,
3-diethylamino-6-methyl-7- (m-trichloroanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-diethylamino- 6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (2 ′,
4'-dimethylanilino) fluoran, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-
8'-methoxybenzoindolinospiropyran, 6'-bromo
-8'-methoxybenzoindolinospiropyran, 3- (2'-
Hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5 '-
Nitrophenyl) phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl ) -3- (2'-Hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyltrifluoromethylanilino) fluoran, 3-pyrrolidino
-7-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluor Oran, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluoran, 3- (N-ethyl-Np-toluidino) -7- (α-phenylethylamino) fluoran, 3-diethylamino-7-
(O-methoxycarbonylphenylethyl) fluoran,
3-diethylamino-5-methyl-7- (α-phenylethylamino) fluoran, 3-diethylamino-7-piperidinofluoran, 2-chloro-3- (N-methyltoluidino) -7- (p-
N-butylanilino) fluorane, 3,6-bis (dimethylamino) fluorenespiro (9,3 ')-6'-dimethylaminophthalide, 3- (N-ethyl-N-cyclohexylamino) -5,6-
Benzo-7-α-naphthylamino-4'-bromofluoran, 3-
Diethylamino-6-chloro-7-anilinofluoran, 3-
(N-ethyl-N-2-ethoxypropylamino) -6-methyl-7
-Anilinofluoran, 3- (N-ethyl-N-tetrafurfurylamino) -6-methyl-7-anilinofluoran 3-diethylamino-6-methyl-7-mesitidino-4 ', 5'-benzo Fluoran, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p
-Dimethylaminophenyl) ethylene-2-yl diphthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p
-Dimethylaminophenyl) ethylene-2-yl｝ -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl)
-3- (1-p-dimethylaminophenyl-1-phenylethylene
-2-yl) phthalide, 3- (p-dimethylaminophenyl)-
3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4 ′
-Dimethylamino-2'-methoxy) -3- (1 "-p-dimethylaminophenyl-1" -p-chlorophenyl-1 ", 3" -butadiene
-4 "-yl) benzophthalide, 3- (4'-dimethylamino-2 '
-Benzyloxy) -3- (1 "-p-dimethylaminophenyl-
1 "-phenyl-1", 3 "-butadiene-4" -yl) benzophthalide, 3-dimethylamino-6-dimethylamino-fluorene
-9-spiro-3 '(6'-dimethylamino) phthalide 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl} -4,5,6,7- Tetrachlorophthalide, 3-
Bis ｛1,1-bis (4-pyrrolidinophenyl) ethylene-2-
Ill-5,6-dichloro4,7-dibromophthalide, bis (p-
Dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane and the like.

In the present invention, various electron-accepting compounds such as a phenolic compound may be used as a developer.
A thiophenolic compound, a thiourea derivative, an organic acid and a metal salt thereof can be used, and specific examples thereof include the following, but are not limited thereto. 4,4'-isopropylidene diphenol, 4,
4'-isopropylidenebis (o-methylphenol), 4,
4'-sec-butylidenebisphenol, 4,4'isopropylidenebis (2-tert-butylphenol), zinc p-nitrobenzoate, 1,3,5-tris (4-tert-butyl-3-hydroxy
-2,6-dimethylbenzyl) isocyanuric acid, 2,2 (3,4'-
Dihydroxydiphenyl) propane, bis (4-hydroxy-3-methylphenyl) sulfide, 4 (β (p-methoxyphenoxy) ethoxy) salicylic acid, 1,7-bis (4-hydroxyphenylphenylthio) -3,5-dioxaheptane , 1,5-bis (4-hydroxyphenylthio) -5-oxapentane,
Monobenzyl phthalate monocalcium salt, 4,4 '
-Cyclohexylidenediphenol, 4,4'-isopropylidenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert- Butyl-2-methylphenol), 1,1,
3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-
5-cyclohexylphenyl) butane, 4,4'-thiobis (6
-tert-butyl-2-methylphenol), 4,4'-diphenolsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4,4-diphenolsulfoxide Isopropyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, benzyl protocatechuate, stearyl gallate,
Lauryl gallate, octyl gallate, 1,3-bis (4-hydroxyphenylthio) propane, N, N'-diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea, salicylanilide, bis ( Methyl 4-hydroxyphenyl) acetate, benzyl bis (4-hydroxyphenyl) acetate, 1,3-
Bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4′-diphenolsulfone, 2,2′-diallyl-4,4′diphenolsulfone, 4-dihydroxy-4'-methyldiphenylsulfone, zinc 1-acetyloxy-2-naphthoate, zinc 2-acetyloxy-1-naphthoate, zinc 2-acetyloxy-3-naphthoate, α, α
-Bis (4-hydroxyphenyl) α-methyltoluene, zinc thiocyanate antipyrine complex, tetrabromobisphenol A, tetrabromobisphenol S, 4,4′-thiobis (2-methylphenol), 4,4′-thiobis ( 2-chlorophenol) and the like.

These developers are 50 to 800% by weight of the color former.
Preferably used, more preferably 100-500
% By weight. If the content is less than 50% by weight, the coloring is not sufficient, and if it is added more than 800% by weight, no further effect can be expected, which is not preferable.

In the present invention, various heat-fusible substances can be used as a sensitivity improver. Specific examples thereof include the following, but are not limited thereto. Fatty acids such as stearic acid and behenic acid; fatty acid amides such as stearic acid amide and palmitic acid amide; fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate; Benzylbiphenyl, terphenyl, triphenylmethane, p-
Benzyloxy benzoyl benzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid phenyl, 1-hydroxy-
Methyl 2-naphthoate, diphenyl carbonate, guaiacol carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene,
1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxyethane, 1,2-
Bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-diphenoxybutane, 1,4-diphenoxy-2-butene, 1,2-
Bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4 diphenylthiobutane, 1,4-diphenylthio-2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4- Bis (2-vinyloxyethoxy) benzene, p (2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, p-
Propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p-benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, 1,2
-Bis (4-methoxyphenoxy) propane, 1,5-
Bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, bis (4-chlorobenzyl) oxalate and the like.

The above-mentioned heat-fusible substance is used alone or as a mixture, and in order to obtain a sufficient thermal response, it is preferable to use 10 to 200% by weight, more preferably, to the developer. 20 to 150% by weight.

The inorganic oil-absorbing substance used in the present invention must be calcium carbonate having an oil absorption of 100 ml / 100 g or more, and can be used in combination with other inorganic oil-absorbing substances (silica, kaolin, talc, etc.). Where the calcium carbonate is
It is preferable that the concentration be 0.2 g / m ² or more.

Further, if necessary, metal soap, wax,
A surfactant, an antistatic agent, an ultraviolet absorber, an antifoaming agent, a conductive agent, a fluorescent ray and the like may be added. As metal soap,
Higher fatty acid metal salts are used, such as zinc stearate, casium stearate, and aluminum stearate. As wax, paraffin wax,
Microcrystalline wax, carnauba wax, methylol stearamide, polyethylene wax, polystyrene wax, fatty acid amide wax and the like are used alone or in combination. As a surfactant,
A sulfosuccinic acid-based alkali metal salt and a fluorine-containing surfactant are used.

It is preferable to add a decoloring inhibitor to the thermosensitive coloring layer in order to prevent decoloration of the image printed portion and to make the formed image fast. A phenol compound, particularly a hindered phenol compound, is effective as the decoloration inhibitor. For example, 1,1,3-tris (2-methyl-4-hydroxy-tert-butylphenyl) butane,
1,3-tris (2-ethyl-4-hydroxy-5-t
tert-butylphenyl) butane, 1,1,3-tris (3,5-di-tert-butyl-4-hydroxyphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert) -Butylphenyl) propane,
2,2'-methylene-bis (6-tert-butyl-4
-Methylphenol), 4,4'-butylidene-bis (6-tert-butyl-3-methylphenol),
4,4'-thio-bis- (3-methyl-6-tert-
Butylphenol), and the like.

The use amount of such a phenolic compound is preferably from 1 to 200% by weight, more preferably from 5 to 50% by weight, based on the developer. These materials are each mixed and then applied to a support.

As the support, paper, synthetic paper, various bases and the like are used, and it is preferable to provide an undercoat layer on the support in advance in order to obtain high smoothness. The applied heat-sensitive recording material is dried and subjected to a treatment such as a calender and used for use.

[0018]

EXAMPLES The present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples. Example 1 (Preparation of undercoat paper) 80 g of calcined kaolin (Ensilhardt: Ansilex 93) was dispersed with a homogenizer together with 160 g of a 0.5% aqueous solution of sodium hexametaphosphate to obtain a pigment dispersion. Styrene-butadiene latex (manufactured by Sumitomo Nogatax: SN30)
7, a solid content concentration of 48%) and a 10% aqueous solution of polyvinyl alcohol (Kuraray: PVA-117) of 24% were added to obtain an undercoat layer coating solution. The undercoat layer coating solution was applied to 50 g / m ² high quality paper at 8 g / m ² and dried to produce an undercoat paper.

(Preparation and application of coating solution for thermosensitive coloring layer) 20 g of 3-dibutylamino-6-methyl-7-anilinofluoran was added to polyvinyl alcohol (Kuraray Co., Ltd .: P
VA-105) The mixture was dispersed in a ball mill for 24 to 48 hours together with 100 g of a 5% aqueous solution to obtain a dispersion having an average particle size of 1.0 μm. Further, 40 g of bisphenol A and 40 g of naphthyl benzyl ether were added to polyvinyl alcohol (Kuraray Co., Ltd .: PVA-105).
% Aqueous solution with a ball mill for 24 to 48 hours to obtain a dispersion having an average particle size of 1.0 μm.

In addition, 80 g of calcium carbonate having an oil absorption of 140 ml / 100 g (Callite KT manufactured by Shiroishi Central Research Institute) is used as a dispersing aid for calcium carbonate as sodium polystyrene sulfonate (Sanyo Chemical Industries, Ltd .: Chemistat SA-9) It was dispersed with a homogenizer together with 160 g of a 1% aqueous solution to obtain a pigment dispersion.

The dispersion thus obtained was mixed, and 50 g of a 21% zinc stearate emulsion was added to obtain a coating solution for thermal paper. Then, the composition was coated on the undercoated paper with a wire bar so that the dry coating amount was 7 g / m ^2, and dried in an oven at 50 ° C. to obtain a heat-sensitive recording material of the present invention.

Example 2 Example 2 was the same as Example 1 except that the dispersion aid of calcium carbonate used in the thermosensitive coloring layer was changed to ammonium polystyrene sulfonate (Sanyo Chemical Industries, Ltd .: Chemistat SA-101). In the same manner as in Example 1, a heat-sensitive recording material was obtained.

Example 3 Example 1 was the same as Example 1 except that the calcium carbonate used in the heat-sensitive coloring layer was changed to calcium carbonate (KK-12, manufactured by Shiraishi Central Laboratory) having an oil absorption of 100 ml / 100 g. In the same manner, a heat-sensitive recording material was obtained.

Example 4 Except that the calcium carbonate used in the thermosensitive coloring layer in Example 1 was changed to a mixture of silica (Shinogi Pharmaceutical Co., Ltd .: FSP101) and a 1: 1 ratio thereof. In the same manner as in Example 1, a thermosensitive recording material was obtained.

Example-5 In place of the silica of Example-4, kaolin (Asia clay:
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the composition was changed to Asian Coat HG).

Example -6 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that talc (FMS) was replaced with talc (LMS200).

Comparative Example 1 The same as Example 1 except that the calcium carbonate used in the thermosensitive coloring layer in Example 1 was changed to calcium carbonate with an oil absorption of 80 ml / 100 g (Callite SA manufactured by Shiroishi Central Research Laboratory). Thus, a heat-sensitive recording material was obtained.

Comparative Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the dispersion aid of calcium carbonate used in the thermosensitive coloring layer was changed to 160 g of a 0.5% aqueous solution of hexametaphosphoric acid. .

Comparative Example 3 The dispersion aid of calcium carbonate used in the thermosensitive coloring layer in Example 1 was replaced with a carboxylic acid copolymer (Kao Soap: Poise 52).
A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the composition was changed to 0).

The heat-sensitive recording material obtained as described above was subjected to a surface treatment with a calender, and the following items were evaluated. The results are shown in Tables 1 and 2. First, use a thermal head (KLT-216-8MPDI) manufactured by Kyocera Corporation and a thermal printing test equipment, head voltage 24V, pulse cycle 10
While using a pressure roll under ms conditions, pulse width 0.8,
Printing was performed at 1.0 and 1.2, and the printing density was measured with a Macbeth reflection densitometer RD-914.

The sharpness of the image is determined by Fuji Xerox Co., Ltd.
Using the ji XEROX 7005 Telecopier, the IEEJ Test Chart No. 3 was copied and evaluated by the sticking of the print sample and the average of the black ratio per dot unit of the halftone portion. The formula for calculating the black ratio per dot unit is as follows.

[0032]

(Equation 1)

The sticking evaluation results are shown as follows. ：: No sticking was observed. Δ: 2-3 white spots (by stick-slip,
(A part that is not printed) occurs, but printing shrinkage does not occur. ×: There are many overexposed areas, and the printing has also shrunk.

The stability of the pigment dispersion was evaluated by the following method. With a 200 mesh filter, 50 l of a 40% by weight pigment dispersion was subjected to pressure filtration at a pressure of 100 kg / m ² , and clogging of the filter was visually observed. ：: good, not clogged Δ: A small amount is clogged but flows. ×: Clogging is remarkable and hardly flows. The degree of sedimentation of the pigment when the dispersion was placed in a beaker and allowed to stand for 24 hours was visually observed. ：: Almost no sedimentation. Δ: A small amount of pigment sediments. X: A large amount of pigment sediments.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

As is clear from Tables 1 and 2, according to the present invention, excellent production suitability such as high sensitivity, excellent image clarity, and dispersion stability of the heat-sensitive layer coating liquid is obtained. Thus, a heat-sensitive recording material is obtained.

Continuation of the front page (56) References JP-A-2-126933 (JP, A) JP-A-62-91416 (JP, A) JP-A-64-65015 (JP, A) JP-A-1-104335 (JP, A) JP-A-64-8090 (JP, A) JP-A-63-312883 (JP, A) JP-A-2-1644582 (JP, A) JP-A-2-258288 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (3)

(57) [Claims] 1. A thermosensitive recording material having a thermosensitive coloring layer provided on a support, wherein the thermosensitive coloring layer has an oil absorption of 1 as a pigment in the thermosensitive coloring layer.
A thermosensitive recording material characterized by containing at least 00 ml / 100 g of calcium carbonate and polystyrene sulfonate as a dispersing aid for the calcium carbonate. 2. The heat-sensitive recording material according to claim 1, wherein the calcium carbonate is used in combination with any one of kaolin, talc and silica. 3. The heat-sensitive recording material according to claim 1, wherein the pigment contains 0.5 to 3% by weight of a polystyrene sulfonate.