JP3176693B2 - 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, and more particularly, to improving the sensitivity and providing a coating solution for an undercoat layer by providing an undercoat layer between a support and a thermosensitive coloring layer. It is also about improvement of workability.

[0002]

2. Description of the Related Art In recent years, various recording materials have been researched, developed and put to practical use in the information recording field in accordance with social demands such as diversification and increase of information, resource saving, and no pollution. Above all, the heat-sensitive recording material is (1) a color image is recorded simply by heating, and a complicated developing step is unnecessary;
(2) It can be manufactured using a relatively simple and compact apparatus, and the obtained recording material can be easily handled and the maintenance cost is low. (3) Paper is often used as a support. In this case, not only is the cost of the support medium inexpensive, but also because of the advantages that the feel of the obtained recorded matter is close to that of plain paper, the output of a computer, the field of a printer such as a calculator, the field of a recorder for medical measurement, It is widely used in the fields of low-speed and high-speed facsimile, automatic ticket vending machines, thermal copying, and the like.

The above-mentioned thermosensitive recording material is usually prepared by coating and drying a thermosensitive coloring layer coating solution containing a coloring component capable of causing a coloring reaction upon heating on a support such as paper, synthetic paper or synthetic resin film. The heat-sensitive recording material thus obtained is heated by a hot pen or a hot head to record a color image.

As a conventional example of such a heat-sensitive recording material, there is, for example, a heat-sensitive recording material disclosed in JP-B-43-4160 or JP-B-45-14039. For example, the thermal responsiveness was low, and sufficient color density was not obtained during high-speed recording.

[0005] As a method for improving such a defect, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran (see Japanese Patent Application Laid-Open No. 49-109120) as a leuco dye, Development of high-sensitivity dyes such as dibutylamino-6-methyl-7-anilinofluoran (see Japanese Patent Application Laid-Open No. 59-190891), and a substance having a good color-forming property as a color developing agent 1,7-bis (4- (Hydroxyphenylthio) -3,5-dioxaheptane
(See JP-A-59-106456), 1,5-bis (4-hydroxyphenylthio) -3-oxapentane (JP-A-59-116262)
It has been proposed to increase the speed and the sensitivity by using the technique described in Japanese Patent Application Laid-Open No. H10-209,878. In addition, JP-A-61-123584, JP-A-61-215087, and JP-A-61-242889 also attempt to increase the speed and sensitivity by combining the substances mentioned above.

On the other hand, a technique using fine hollow particles (see JP-A-59-5093) as a technique for improving the heat insulating property of the undercoat layer and increasing the sensitivity, and two types of fillers having different expansion ratios due to heating. (Japanese Unexamined Patent Publication No. 1-9768)
No. 0).

However, such hollow fillers having a large particle size of 3 to 10 μm and a high porosity of 80% or more contain a large amount of air. Has the drawback that the coating is difficult to apply due to floating of the coating. In addition, the particle size is 1 μm or less,
A heat-sensitive recording material using a hollow filler having a hollow ratio of 80% or less had sufficiently high sensitivity in the past, but recently, a heat-sensitive recording material with higher sensitivity has been required.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material in which the above-mentioned conventional disadvantages are improved.
That is, it is an object of the present invention to provide a thermosensitive recording material having high sensitivity and improved stability of a coating solution for an undercoat layer.

[0009]

According to the present invention, there is provided a thermosensitive recording material comprising a support and an undercoat layer containing a plastic spherical hollow filler and a thermosensitive coloring layer mainly containing a leuco dye and a developer. A heat-sensitive recording material comprising a mixture of a filler A having a particle size of 1 μm or less and a hollow ratio of 80% or less and a filler B having a particle size of 3 to 10 μm and a hollow ratio of 80% or more as a hollow filler. .

[0010] The filler of the undercoat layer generally used for the thermosensitive recording material is charcoal, silica, kaolin,
Inexpensive and inorganic pigments such as talc, clay and calcined kaolin are used. These contribute to the improvement of the sensitivity to some extent because they fill the irregularities of the base paper and improve the smoothness as the thermal paper, but a large improvement in the sensitivity cannot be expected due to insufficient heat insulation.

On the other hand, a hollow filler having good heat insulating properties has a particle size of 1
Although a hollow filler with a hollow ratio of 80% or less is generally used, a larger filler having a particle size of 3 to 10 μm and a hollow ratio of 80% or more should be used to further improve the heat insulation. Has been desired theoretically. However, when such a large-diameter, high-hollow-filled hollow filler is placed in an undercoat layer coating solution, it floats in the solution and does not adapt to the solution. .

However, the particle size is 1 μm or less and the hollow ratio is 8
Hollow filler of 0% or less, particle size of 3-10 μm, hollow ratio of 80
% Or more of the hollow filler in a ratio of 9: 1 to 1: 9 is used, so that the undercoat layer has good heat insulating properties,
It has been found that a thermosensitive recording material with good compatibility of hollow particles can be provided as an undercoat layer coating solution.

Here, the hollow ratio is a ratio of the outer diameter to the inner diameter of the hollow particles, and is represented by the following equation.

(Equation 1)

The plastic spherical hollow particles used in the present invention include polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate, polyacrylonitrile, polybutadiene, and copolymers thereof. As the gas contained in the shell, propane, butane, air and the like are generally used.

In order to provide the undercoat layer on a support, the plastic spherical hollow particles are dispersed in water together with a binder such as a known water-soluble polymer or aqueous polymer emulsion, and this is coated on the support surface. And dried. In this case, the coating amount of the plastic spherical hollow particles is at least 1 g, preferably about ^{2 to} 15 g per 1 m ² of the support, and the coating amount of the binder resin is such that the undercoat layer is strongly bonded to the support. Usually, it is 2 to 50% by weight based on the total amount of the plastic spherical hollow particles and the binder resin.

As a specific example of the hollow filler having a particle diameter of 1 μm or less and a hollow ratio of 80% or less, OP-62 HV-91 manufactured by Rohm & Haas Muticle 1103E manufactured by Mitsui Toatsu Chemicals Co., Ltd. Particle diameter of 3 to 10 μm or less Specific examples of the hollow filler having a hollow ratio of 80% or more include a hollow filler R-3 manufactured by Matsumoto Yushi Seiyaku Co., Ltd., but are not limited thereto.

In the present invention, the binder used for forming the undercoat layer is appropriately selected from conventionally known water-soluble polymers and / or aqueous polymer emulsions. Specific examples thereof include water-soluble polymers such as polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / Acrylic ester copolymer, acrylamide / acrylic ester / methacrylic acid terpolymer, styrene /
Examples thereof include a maleic anhydride copolymer alkali salt, an isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and the like. Examples of the aqueous polymer emulsion include latexes such as styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, vinyl acetate resin, vinyl acetate / acrylic acid copolymer, styrene / acrylic ester copolymer, Emulsions such as acrylic ester resins and polyurethane resins are exemplified.

In the undercoat layer of the present invention, together with the plastic spherical hollow particles and the binder, if necessary, auxiliary additives commonly used in this type of heat-sensitive recording material, for example, fillers, heat-fusible materials ,
Surfactants and the like can be used in combination. In this case, specific examples of the filler and the heat-fusible substance include various substances described below in relation to the thermosensitive coloring layer component.

Since the surface of the undercoat layer formed on the support as described above has considerable irregularities, the surface may be smoothed by calendering after the formation of the undercoat layer.

In the present invention, the leuco dye used in the color-forming layer may be used alone or as a mixture of two or more. As such a leuco dye, those applied to this type of thermosensitive recording material are optional. For example, leuco compounds of dyes such as triphenylmethane, fluoran, phenothiazine, auramine, spiropyran, and indolinophthalide are preferably used. Specific examples of such leuco dyes include, for example, those shown below. 3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactan), 3,3-bis (p- Dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p
-Dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7-
Dimethylfluoran, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrolospirane , 6'-bromo-3'-methoxy-
Benzoindolino-pyrrospirane, 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'-dimethyl Aminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) furiolan, 3-pyrrolidino-7-
Trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran , 3-diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3- (Np-tolyl-N-
Ethylamino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 2- ｛N- (3'-
(Trifluoromethylphenyl) amino} -6-diethylaminofluoran, 2- {3,6-bis (diethylamino) -9- (o
-Chloranilino) lactam xanthylbenzoate｝, 3-
Diethylamino-6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-N-methyl -N-Amylamino-6-
Methyl-7-anilinofluoran, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-pyrrolidino- 7- (di-p-chlorophenyl) methylaminofluoran, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluoran, 3- (N-ethyl-p-toluidino)-
7- (α-phenylethylamino) fluoran, 3-diethylamino-7- (o-methoxycarbonylphenylamino)
Fluoran, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluoran, 3-diethylamino-7-
Piperidinofluoran, 2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluoran, 3- (N-
Methyl-N-isopropylamino) -6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3,6-bis (dimethylamino) fluorenespiro (9,3 ') -6-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4'-bromofluoran, 3-diethylamino-6-
Chlor-7-anilinofluoran, 3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-tetrahydrofurfurylamino-6 -Methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-mesitidino-4 ', 5'-benzofluoran and the like. 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluoran, 3-N
-Ethyl-N-isoamyl-6-methyl-7-anilinofluoran, 3-N-diethylamino-6-methyl-7- (2 ′, 4′-dimethylanilino) fluoran,

In the present invention, various compounds having an electron accepting property as a color developing agent, for example, a phenolic compound,
A thiophenolic compound, a thiourea derivative, an organic acid and a metal salt thereof can be used in combination as needed, and specific examples are shown below. 4,4'-isopropylidenebisphenol, 4,4'-isopropylidenebis (o-methylphenol), 4,4'-secondarybutylidenebisphenol,
4,4'-isopropylidenebis (2-tert-butylphenol), 4,4'-cyclohexylidenediphenol, 4,
4'-isopropylidenebis (2-chlorophenol), 2,2 '
-Methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-2-methyl) phenol , 1,1,3-tris (2-methyl-
4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-
Tris (2-methyl-4-hydroxy-5-tert-cyclohexylphenyl) butane, 4,4′-thiobis (6-tert-butyl-2
-Methyl) phenol, 4,4'-diphenolsulfone, 4-
Isopropoxy-4'-hydroxydiphenylsulfone, 4-
Benzyloxy-4'-hydroxydiphenylsulfone, 4,4 '
-Diphenol sulfoxide, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3, 5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, 1,3-bis (4
-Hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N'-
Diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy- Metal salts of 2-naphthoic acid and hydroxynaphthoic acid such as zinc, aluminum and calcium. Bis (4-hydroxyphenyl) acetic acid methyl ester, bis (4-hydroxyphenyl) acetic acid benzyl ester, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4'-diphenolsulfone, 3,3'-diallyl-4,4'-diphenolsulfone, 2,2-bis (4-hydroxyphenyl) -α-methyltoluene, zinc thiocyanate antipyrine complex, tetra Bromobisphenol A, tetrabromobisphenol S, 3,4-dihydroxy-4′-methyl-diphenylsulfone,

In order to improve the thermal response, a heat-fusible substance can be contained in the thermosensitive coloring layer. Examples of preferred heat-fusible substances include benzyl p-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 ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-isopropylphenyl ether, 1,4-butanediol-p-tert-octylphenyl ether, 1-phenoxy-2- (4-ethylphenoxy) ethane, 1-phenoxy-2- (4-chlorophenoxy) ethane, 1,4-butanediolphenyl Ether, diethylene glycol bis (4-
Methoxyphenyl) ether and the like. The heat-fusible substance is used alone or as a mixture, and in order to obtain a sufficient thermal response, 10 to 30 with respect to the electron-accepting compound.
0% by weight, preferably 20% by weight.
~ 200% by weight.

Examples of the binder used in the coloring layer include polyvinyl alcohol, starch and derivatives thereof,
Cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid ternary copolymer Coal, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc., as well as polyvinyl acetate, polyurethane, styrene / Butadiene copolymer, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, styrene / butadiene / Or a latex such as acrylic copolymer.

As the filler, auxiliary additives commonly used in this type of heat-sensitive recording material, such as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, In addition to surface-treated inorganic fine powders such as calcium and silica,
Examples include organic fine powders such as formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin.

In addition, sensitizers, lubricant waxes, surfactants, auxiliaries and the like generally used in the heat-sensitive coloring layer can be used if necessary.

The heat-sensitive recording material of the present invention is prepared by, for example, applying and drying a coating solution for forming a color-forming undercoat layer and a heat-sensitive color-forming layer containing the above-mentioned components on a support such as paper, synthetic paper, or plastic film. Then, it is obtained by calendering. In this case, it is also possible to provide an overcoat layer on the coloring layer. Leuco dye, developer,
The appropriate amounts of other auxiliary additives are 5 to 40% by weight and 20 to 60% by weight, respectively.

[0027]

Next, the present invention will be described in more detail with reference to examples. The parts and percentages shown below are based on weight.

Example 1 [Solution A] 20 parts 3- (N-methyl-3-N-cyclohexyl) amino 6-methyl-7-anilinofluoran 20 parts aqueous 10% polyvinyl alcohol solution 60 parts water [Solution B] 1,5-bis (4-hydroxyphenylthio) -6-methyl-7 10 parts -anilinofluoran -Calcium carbonate 15 parts -Polyvinyl alcohol 10% aqueous solution 25 parts -Water 50 parts The above composition Each of which has an average particle size of 2.5.
μm or less using a sand mill.
Solution B] and [Solution B] were prepared.

[Liquid C] 15 parts of plastic spherical hollow particle dispersion (filler B) (solid concentration 32%, average particle diameter 5 μm, hollow ratio 92%) 15 parts of plastic spherical hollow particle dispersion (filler A) (Rohm and Haas OP-62, solid content 37.5%, average particle diameter 0.4μm, hollowness 65%) ・ Styrene / butadiene copolymer latex (solid content 47.5%) 10 parts ・ Water 60 parts The undercoat layer coating solution was prepared by stirring and dispersing a mixture consisting of the following, and this was commercialized high-quality paper (basis weight: 52 g / m ² )
Was dried and then coated and dried so that the weight was 5 g / m ² to obtain an undercoated paper.

Next, the above [Solution A] and [Solution B] are mixed and stirred at a weight ratio of 1:10 to prepare a thermosensitive coloring layer forming solution, which is dried on the surface of the undercoated paper. After coating and drying so as to have a weight of 5 g / m ² and providing a heat-sensitive coloring layer, a super calender treatment was further performed so that the Beck smoothness became 600 to 700 seconds to obtain a heat-sensitive recording material of the present invention. .

Example 2 As a plastic spherical hollow particle dispersion (filler B) in the liquid C of Example 1, another plastic spherical hollow particle dispersion (solid concentration: 30%, average particle diameter: 10 μm, hollow ratio: 93%)
%) Was used in the same manner as in Example 1 to obtain a thermosensitive recording material.

Example 3 A plastic spherical hollow particle dispersion (filler B) in the liquid C of Example 1 was used as another plastic spherical hollow particle dispersion (solid content: 30%, average particle diameter: 9 μm, hollow ratio: 93%).
%) Was used in the same manner as in Example 1 to obtain a thermosensitive recording material.

Example 4 Another plastic spherical hollow particle dispersion (solid content: 30%, average particle diameter: 3 μm, hollow ratio: 96) was used as the plastic spherical hollow particle dispersion (filler B) in the liquid C of Example 1.
%) Was used to obtain a thermosensitive recording material.

Example 5 As a plastic spherical hollow particle dispersion (filler B) in the liquid C of Example 1, another plastic spherical hollow particle dispersion (solid content: 32%, average particle diameter: 7 μm, hollow ratio: 89)
%) Was used in the same manner as in Example 1 to obtain a thermosensitive recording material.

Comparative Example 1 In Example 1, only filler A was used without using filler B.
A thermosensitive recording material for comparison was obtained in the same manner as in Example 1 except that 30 parts were used.

Comparative Example 2 A comparative thermosensitive recording material was obtained in the same manner as in Example 1, except that 30 parts of filler plastic spherical non-hollow particles B were used without using plastic spherical hollow fine particles A.

The thermal recording material thus obtained was tested for dynamic sensitivity and dot reproducibility. The results are shown in Table 1. In addition, the test method was performed as follows.

Dynamic color development: Using a thermal printing tester equipped with a thin film head manufactured by Matsushita Electronic Components, under the conditions of head power 0.45 W / dot, one line recording time 20 ms / l, and scanning line density 8 × 3.85 dots / mm. Were printed with pulse widths of 0.3, 0.4, 0.5 and 0.6 msec, and the print density was measured with a Macbeth densitometer RD-914. Dot reproducibility: The image obtained by the test method was visually evaluated. 5 rank evaluation 5 Very good 2 Poor 4 Good 1 Very bad 3 Normal Head matching: Evaluation was made based on the amount of scum adhering to the head during the test. 5 rank evaluation Liquidity: The liquid separating property (whether or not the filler floats) was evaluated 1 hour after the undercoat liquid was prepared. 5 rank evaluation

[0039]

[Table 1] Table 1

From the results shown in Table 1, the heat-sensitive recording materials of the examples were as follows:
It can be seen that it has high sensitivity and is excellent in dot reproducibility, head matching property and liquid property.

[0041]

As described above, according to the heat-sensitive recording material of the present invention, an extremely practical heat-sensitive recording material having high sensitivity and improving the liquid property at the time of coating the undercoat layer can be obtained.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-573 (JP, A) JP-A-3-147888 (JP, A) JP-A-3-33296 (JP, A) JP-A-4- 129797 (JP, A) JP-A-1-97680 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (2)

(57) [Claims] 1. A thermosensitive recording material comprising a support and an undercoat layer containing a plastic spherical hollow filler and a thermosensitive coloring layer containing a leuco dye and a developer as main components, wherein the hollow filler has a particle size of 1 μm. Hereinafter, a filler A having a hollow ratio of 80% or less, a particle size of 3 to 10 μm, and a hollow ratio of 8
A heat-sensitive recording material comprising a mixture of 0% or more of filler B. 2. The filler B has a particle size of 3 to 10 μm,
2. The heat-sensitive recording material according to claim 1, wherein a filler having a hollow ratio of 90% or more is used.