JP3173751B2 - 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 having excellent dynamic color sensitivity and fineness.

[0002]

2. Description of the Related Art A thermosensitive recording material comprises a support provided with a thermosensitive coloring layer mainly composed of an electron-donating colorless or pale-colored dye precursor and an electron-accepting developer. By heating with a head, a hot pen, a laser beam or the like, the dye precursor and the developer react instantaneously to obtain a recorded image. Such a heat-sensitive recording material has advantages that a recorded image can be obtained with a relatively simple device, maintenance is easy, and noise is less generated. Therefore, it is widely used as a recording material for facsimile, labels, printers, ticket vending machines, and the like. It's being used. By the way, in recent years, the speed of the recording field has been increased, and there has been a demand for a recording material that can cope with the speeding up. Therefore,
Various recording materials for realizing high sensitivity have been proposed. One known method for improving color sensitivity is to add a compound that melts at a lower temperature than the leuco dye and the developer and has a high ability to dissolve both (generally called a fusible substance). Have been. However, in this method, there is a problem that the background portion develops color during continuous recording of the heat-sensitive recording sheet due to heat storage around the head (color development of residual heat). The challenge is to increase the color sensitivity. To suppress background fog and increase dynamic color sensitivity,
JP-A-55-164192 discloses that the thermal conductivity of a support is set to 0.04 Kcal / mh ° C. or less, and JP-A-59-50903 and JP-A-59-1761.
No. 85 and Japanese Unexamined Patent Publication (Kokai) No. Sho 59-225987 have proposed providing a layer mainly composed of fine hollow sphere particles on a support, but these have insufficient foaming properties. In some cases, the adhesion between the thermal head and the heat-sensitive recording material may be insufficient, and it cannot be said that sufficiently satisfactory results have been obtained.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks found in the prior art, and in particular, to provide a thermosensitive image recording system capable of recording images with high dynamic color sensitivity and high uniformity and high definition. To provide a recording material.

[0004]

According to the present invention, there is provided a heat-sensitive recording material provided with a thermosensitive coloring layer comprising at least a leuco dye and a developer on a support, wherein at least a heat-sensitive coloring layer is provided between the support and the thermosensitive coloring layer. An intermediate layer containing vulcanized rubber fine particles is provided.

[0005] Further, the present invention is characterized in that the intermediate layer further contains plastic hollow fine particles.

Further, the present invention is characterized in that the average particle diameter of the rubber fine particles is 20 μm or less, and the rubber hardness measured by a measuring method specified in JIS K6301 is 100 or less.

The intermediate layer having the vulcanized rubber particles of the present invention acts as a heat insulating layer and an elastic layer, has excellent adhesion to a thermal head, and improves sensitivity by efficiently utilizing thermal energy from the thermal head. In addition, it provides a color image having excellent definition. In addition, by using the rubber fine particles and the plastic hollow fine particles in combination, the effect as a heat insulating layer is enhanced, and the sensitivity is further improved.

The rubber fine particles in the present invention include vulcanized silicon rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, isoprene rubber, chloroprene rubber, ethylene-propylene rubber, butyl rubber, acrylic rubber, chlorosulfonated polyethylene. Fine particles of rubber, fluorine rubber, urethane rubber, polysulfide rubber and the like can be mentioned. Further, these rubber fine particles have a three-dimensional network structure by forming a bridge between rubber molecular chains by vulcanization to increase elasticity. Generally, sulfur powder, organic peroxide, zinc oxide, polyamine and the like are added. Used as a sulfurizing agent. As the plastic hollow fine particles used in the present invention, a thermoplastic resin or a thermosetting resin is used as a shell, and air or other gas is contained therein. Those having a uniform diameter distribution peak are preferred. The average particle diameter of the hollow plastic fine particles is preferably 20 μm or less, more preferably 10 μm or less. The hollow ratio of the hollow plastic fine particles is preferably 40% or more.

In the present invention, an inorganic pigment is optionally used as a component of the intermediate layer. In this case, a pigment having an oil absorption of 30 ml / 100 g or more, preferably 80 ml / 100 g or more is selected. Is done. As these inorganic pigments, one or more kinds of pigments commonly used in this type of heat-sensitive recording material can be selected. Specific examples thereof include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and inorganic pigments such as surface-treated calcium and silica.

In order to produce the heat-sensitive recording material of the present invention,
When an intermediate layer containing rubber fine particles, plastic hollow fine particles and the like is bonded and supported on a support, various conventional binders can be appropriately used. Specific examples of such a binder include the following.

Polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate Water-soluble polymers such as terpolymer / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt of isobutylene / maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, casein, etc. Vinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer Emulsion and styrene / butadiene copolymers such as the body, styrene / butadiene / latex such as acrylic copolymer.

In the present invention, the leuco dye used in the heat-sensitive coloring layer is used alone or in combination of two or more. As such a leuco dye, those applied to this kind of heat-sensitive material are optional. Applied to, for example, triphenylmethane, fluoran, phenothiazine,
Leuco compounds of dyes such as 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 bioreductolactone), 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-methyl-N-isobutyl-6-methyl-7-anilinofluoran, 3-N-ethyl-N-
Isoamyl-6-methyl-7-anilinofluoran, 3
-Diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7,8-benzfluoran, 3-diethylamino-6
-Methyl-7-chlorofluorane, 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-chloroanilino) xanthyl lactam lactam}, 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-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluoran, 3 -(N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino)
Fluoran, benzoyl leucomethylene bleu, 6'-
Chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-3'-methoxy-benzoindolino-spiropyran, 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
-Propyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7-
(N-benzyl-trifluoromethylanilino) fluoran, 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- [alpha] -naphthylamino-4'-bromofluoran, 3-diethylamino-6-chloro-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' −
Benzofluorane, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3-} 1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-phenyl Ethylene-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-Butadien-4-yl) benzophthalide,
3- (4'-dimethylamino-2'-benzyloxy)
-3- (1-p-dimethylaminophenyl-1-phenyl-1,3-butadien-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-yl} -5,6-dichloro-4,7-dibromophthalide, bis (p-dimethyl (Aminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane and the like.

Further, in the present invention, various electron-accepting compounds which develop color upon contact with the leuco dye as a color developer, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, etc. Can be used in combination, and specific examples thereof include the following.

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-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tertya) 1,1,3-tris (2-methyl-4-hydroxy) -5-cyclohexylphenyl) butane, 4,4'-thiobis (6-tert-butyl-2)
-Methyl) phenol, 4,4'-diphenolsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenolsulfoxide, P-hydroxy Isopropyl benzoate, 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-2-naphthoic acid, metal salts of 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′-diphenol sulfone, 3,3′-diallyl-4,4′-diphenol sulfone, α, α-bis (4
-Hydroxyphenyl) -α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, 4,4′-
Thiobis (2-methylphenol), 4,4'-thiobis (2-chlorophenol) and the like.

In order to produce the heat-sensitive recording material of the present invention,
When the leuco dye and the developer are bound and supported on the support, various conventional binders can be appropriately used, and specific examples thereof include specific examples of the binder for binding the intermediate layer on the support. Selected from among

In the present invention, various heat-fusible substances can be used as the sensitivity improver, and specific examples thereof include, but are not limited to, the following. Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, zinc stearate, aluminum stearate, calcium stearate, zinc palmitate,
Fatty acid metal salts such as zinc behenate, p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl, 1-hydroxy-2-
Phenyl naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl carbonate, dalayacol carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-ethoxynaphthalene, 1,4-dibenzyl Roxynaphthalene, 1,
2-diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 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-aryl Oxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenylethanol, 1,1
-Diphenylpropanol, p-benzyloxybenzyl alcohol, 1,3-diphenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) propane , 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (oxalate)
-Methylbenzyl), bis (4-chlorobenzyl) oxalate and the like.

In the present invention, together with the leuco dye and the developer, if necessary, auxiliary additives commonly used in this type of heat-sensitive recording material, for example, fillers, surfactants, lubricants, and pressure color prevention. Agents and the like can be used in combination. In this case, as the filler, for example, inorganic fine powders such as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated calcium and silica And organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, vinylidene chloride resin, and the like. As the lubricant, higher fatty acid and its metal salt, higher fatty acid amide ,
Examples include higher fatty acid esters, various animal, vegetable, mineral or petroleum waxes.

In the present invention, a layer containing a pigment, a binder, a heat-fusible substance and the like can be provided between the intermediate layer and the heat-sensitive coloring layer, if necessary, as another intermediate layer. Further, the heat-sensitive recording material of the present invention can improve the storage stability of a recorded image, and can be provided with a protective layer on the heat-sensitive coloring layer for the purpose of improving the writability of the recording material. In such a case, the above-mentioned pigments, binders, heat-fusible substances and the like can be used as components constituting the protective layer.

[0020]

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

Example 1 The following mixture was stirred and dispersed to obtain a liquid for forming an intermediate layer. (A liquid) 30 parts of 30% silicon rubber fine particle dispersion liquid 90 parts (average particle diameter: 15 μm, rubber hardness: 110) 50% styrene-butadiene latex: 10 parts
On the surface of 2), an intermediate layer coated paper was obtained by coating and drying so that the dry adhesion amount was 5.0 g / m 2.

Using a magnetic ball mill, a mixture having the following composition was dispersed for 24 hours (solution B) so that the average particle diameter became 2.0 μm, and (liquid C) was dispersed for 15 hours. It was prepared to have a diameter of 2.5 μm. (Solution B) 3-Dibutylamino-6-methyl-7-anilinofluoran 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts (Solution C) 20 parts of bisphenol A 10 parts of calcium carbonate 10 parts 10% aqueous solution of polyvinyl alcohol 30 parts 40 parts of water Next, 20 parts of (liquid B) and 80 parts of (liquid C) were mixed to form a thermosensitive coloring layer forming liquid, which was applied to the surface of the above-mentioned intermediate layer-coated paper so that the amount of adhesion after drying was 3.5 g / m 2. After coating and drying to provide a heat-sensitive coloring layer, surface treatment was performed with a super calender to prepare a heat-sensitive recording material of the present invention.

Example 2 A heat-sensitive recording material was produced in the same manner as in Example 1 except that the following (Solution D) was used instead of (Solution A). (D liquid) 90% 30% silicone rubber fine particle dispersion 90 parts (average particle diameter 3 μm, rubber hardness 80) 50% styrene-butadiene latex 10 parts

Example 3 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the following (Solution E) was used instead of (Solution A). (E liquid) 30% butadiene rubber fine particle dispersion liquid 90 parts (average particle diameter 5 μm, rubber hardness 50) 50% styrene-butadiene latex 10 parts

Example 4 A heat-sensitive recording material was produced in the same manner as in Example 1 except that the following (Solution F) was used instead of (Solution A). (F liquid) 90 parts of 30% isoprene rubber fine particle dispersion liquid (average particle diameter 5 μm, rubber hardness 30) 50% styrene-butadiene latex 10 parts

Example 5 A heat-sensitive recording material was produced in the same manner as in Example 1 except that the following (Solution G) was used instead of (Solution A). (Solution G) 30% silicone rubber fine particle dispersion 45 parts (average particle diameter 3 μm, rubber hardness 80) 30% plastic hollow fine particle dispersion 45 parts (styrene-acrylic copolymer, average particle diameter 3 μm, hollow ratio 50%) 10% 50% styrene-butadiene latex

Example 6 A heat-sensitive recording material was produced in the same manner as in Example 1 except that the following (H solution) was used instead of (A solution). (H solution) 30% styrene-butadiene rubber fine particle dispersion 45 parts (average particle diameter 5 μm, rubber hardness 30) 30% plastic hollow fine particle dispersion 45 parts (styrene-acrylic copolymer, average particle diameter 3 μm, hollow ratio) 50%) 50% styrene-butadiene latex 10 parts

Comparative Example 1 A heat-sensitive recording material was produced in the same manner as in Example 1 except that the following (Solution I) was used instead of the (Solution A). (Solution I) 30% styrene-acrylic resin fine particle dispersion 90 parts (average particle size 3 μm) 50% styrene-butadiene latex 10 parts

Comparative Example 2 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the following (Solution J) was used in place of (Solution A). (Solution J) 30% plastic hollow fine particle dispersion liquid 90 parts (styrene-acrylic copolymer, average particle diameter 3 μm, hollow ratio 50%) 50% styrene-butadiene latex 10 parts

The following tests were performed on the heat-sensitive recording materials produced as described above. Table 1 shows the results. Dynamic color sensitivity: using a simulator printing device manufactured by Okura Electric Co., Ltd., head power 0.45 W / dot, scanning line density 8 ×
Pulse width of 0.1 to 1.2 under the condition of 7.7 dots / mm
Printing was performed at intervals of 0.1 msec until msec, and the printing density was measured with a Macbeth densitometer RD-914, and the energy per dot where the printing density was 1.0 was determined. Fineness: Using a simulator printing device manufactured by Okura Electric Co., Ltd., head power 0.45 W / dot, scanning line density 8 ×
One dot pattern was printed with a pulse width where the print density was 1.0 under the condition of 7.7 dots / mm, and the reproducibility of the dots was visually judged with an optical microscope and ranked. 5: Dots are faithfully reproduced 4: Dots are reproduced faithfully 3: Dots can be discriminated but slightly blurred 2: Dots are slightly blurred and missing 1: Dots are blurred and determined Can not

[0031]

[Table 1] From Table 1, it can be seen that those of Examples are excellent in both dynamic color sensitivity and fineness. It can also be seen that the use of plastic hollow microparticles in combination results in a better product.

[0032]

As described above, according to the present invention, by providing an intermediate layer having at least vulcanized rubber fine particles between a support and a thermosensitive coloring layer, a thermosensitive recording excellent in sensitivity and excellent in definition is provided. Material can be obtained.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-270133 (JP, A) JP-A-5-139035 (JP, A) JP-A-5-38874 (JP, A) 573 (JP, A) JP-A-4-358882 (JP, A) JP-A-4-35881 (JP, A) JP-A-3-272887 (JP, A) JP-A-64-55278 (JP, A) JP-A-63-299973 (JP, A) JP-A-63-21180 (JP, A) JP-A-59-204595 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (3)

(57) [Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer comprising at least a leuco dye and a developer,
A heat-sensitive recording material, wherein an intermediate layer containing at least vulcanized rubber fine particles is provided between the support and the thermosensitive coloring layer. 2. A heat-sensitive recording material according to claim 1, wherein said intermediate layer further contains plastic hollow fine particles. 3. The vulcanized rubber fine particles have an average particle size of 20 μm or less, and have a rubber hardness of 100 or less measured by a measuring method specified in JIS K6301. The heat-sensitive recording material as described.