JPH0781222A - Thermal recording material - Google Patents

Abstract

PURPOSE:To raise a dynamic color-forming sensitivity to perform uniform image recording with a high density and a high accuracy by providing a thermal color-forming layer made of at least a leuco dye and a color developer on a substrate the surface of which is coated with a vulcanized rubber. CONSTITUTION:A thermal recording material is formed by providing a thermal color-forming layer mainly composed of an electron donative colorless or light- colored dye precursor and an electron accepting color developer on a substrate. An image is recorded thereon by reacting the dye precursor with the color developer by heating the layer by a thermal head, a laser light, or the like. In this invention, the surface of a substrate is coated with a vulcanized rubber. A thermal color-forming layer made of a leuco dye and a color developer is provided on the substrate. An intermediate layer containing plastic hollow fine particles is provided between the substrate and the thermal recording layer, as required. The coating layer of the vulcanized rubber is preferably made of a rubber having a rubber hardness of 100 or lower measured by a measuring method specified by JIS K 6301.

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 excellent in dynamic color development sensitivity and fineness.

[0002]

2. Description of the Related Art A heat-sensitive recording material comprises a support and a heat-sensitive coloring layer containing an electron-donating colorless or light-colored dye precursor and an electron-accepting developer as main components. 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. Since such a heat-sensitive recording material has the advantages that a recorded image can be obtained with a relatively simple device, maintenance is easy, and noise is minimal, it is widely used as a recording material for facsimiles, labels, printers, ticket vending machines, etc. It's being used. By the way, in recent years, the speed of the recording field has increased, and there has been a demand for a recording material capable of coping with it. Therefore,
Various recording materials have been proposed to achieve high sensitivity. One of the methods to improve the color development sensitivity is to add a compound (generally called a heat fusible substance) that melts at a lower temperature than the leuco dye and the developer and has a high ability to dissolve both. Has been. However, in this method, there is a problem that the background part of the thermal recording sheet develops color during continuous recording due to heat accumulation around the head (coloring of residual heat), so that the coloring start temperature is not lowered and The challenge is to increase the color development sensitivity. In order to suppress the background fog and increase the dynamic color development sensitivity,
JP-A-55-164192 discloses that the thermal conductivity of a support is 0.04 Kcal / mh ° C. or less, and JP-A-59-50903 and JP-A-59-1761.
In JP-A-85-225987 and JP-A-59-225987, it is proposed to provide a support with a layer containing fine hollow sphere particles as a main component, but these have insufficient foamability. In some cases, the adhesion between the thermal head and the thermosensitive recording material may be insufficient, and it cannot be said that sufficiently satisfactory results have been obtained.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to overcome the drawbacks of the prior art described above, and in particular, to obtain an image having high dynamic coloration sensitivity, uniform and high density and excellent image definition. To provide recording material.

[0004]

The present invention is characterized in that a thermosensitive coloring layer comprising at least a leuco dye and a color developer is provided on a support whose surface is covered with vulcanized rubber. I am trying.

The present invention is also characterized in that an intermediate layer containing hollow plastic particles is provided between the support coated with the vulcanized rubber and the heat-sensitive recording layer.

Further, the present invention is characterized in that the coating layer made of the vulcanized rubber is formed of a rubber having a rubber hardness of 100 or less measured by a measuring method specified in JIS K6301. I am trying.

The heat-sensitive recording material having the rubber coating layer of the present invention acts as a heat insulating layer and an elastic layer, has excellent adhesion to the thermal head, and improves the sensitivity by efficiently utilizing the thermal energy from the thermal head. At the same time, a color image having excellent definition is provided. Further, by using an intermediate layer of the support having the rubber coating layer and the plastic hollow fine particles in combination, the effect as a heat insulating layer is enhanced, and the sensitivity is further improved.

As the material of the rubber coating layer in the present invention, vulcanized silicone rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, isoprene rubber, chloroprene rubber, ethylene-propylene rubber, butyl rubber, acrylic rubber, chloro rubber. Sulfonated polyethylene rubber, fluoro rubber, urethane rubber,
Examples thereof include polysulfide rubber. In addition, these rubbers have a three-dimensional network structure to increase elasticity by forming crosslinks between rubber molecular chains by vulcanization, and generally sulfur powder, organic peroxide, zinc oxide, polyamine, etc. are vulcanized. Used as an agent. The thickness of the rubber coating layer in the present invention is 1
It is desirable that the thickness is in the range of μm to 50 μm. When the thickness is less than 1 μm, it is insufficient to obtain the effect of the present invention.
If it is thicker than the above, the cost is high and the proportion of the heat-sensitive recording paper is large, and the heat-sensitive recording paper as a whole is unfavorable. The plastic hollow fine particles used in the present invention include a thermoplastic resin or a thermosetting resin as a shell and contain air or other gas inside, which are fine hollow particles which are already in a foamed state, and have an average particle size. It is preferable that the diameter distribution peaks are uniform.
The average particle size of the hollow plastic particles is 20μ
m or less, and more preferably 10 μm or less. The hollow rate of the hollow plastic particles is 40%.
The above is preferable.

In the present invention, an inorganic pigment is optionally used as a component of the intermediate layer. In this case, the pigment having an oil absorption of 30 ml / 100 g or more, preferably 80 ml / 100 g or more is selected. To be done. As these inorganic pigments, one or more 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, hollow plastic fine particles, etc. is bonded and supported on a support, various conventional binders can be appropriately used. Specific examples of such a binder include the followings.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester. / Methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and other water-soluble polymers, and poly Vinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, 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.

The leuco dyes used in the thermosensitive coloring layer in the present invention may be applied alone or in admixture of two or more, and as such leuco dyes, those applied to this type of thermosensitive material are optional. Applied to, for example, triphenylmethane-based, fluorane-based, phenothiazine-based,
Leuco compounds of dyes such as auramine type, spiropyran type and indolinophtalide type are preferably used. Specific examples of such leuco dyes include those shown below.

3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3 -Bis (p-dimethylaminophenyl) -6-diethylaminophthalide,
3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5 , 7-Dimethylfluorane, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-
Isoamyl-6-methyl-7-anilinofluorane, 3
-Diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2
-{3,6-bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoate lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (O
-Chloroanilino) fluorane, 3-dibutylamino-
7- (o-chloroanilino) fluorane, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-
6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane, 3 -(N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino)
Fluoran, benzoyl leuco methylene blue-, 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) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-
(N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5
-Chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α-
Phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α
-Phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3-
(N-methyltoluidino) -7- (pn-butylanilino) fluorane, 3- (N-methyl-N-isopropylamino) -6-methyl-7-anilinofluorane, 3
-Dibutylamino-6-methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorenspyrro (9,3 ')-6'-dimethylaminophthalide, 3-
(N-benzyl-N-cyclohexylamino) -5,6
-Benz-7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino-6- Methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane, 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-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-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 the above leuco dye as a color developing agent upon contact, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, etc. Can be used, and specific examples thereof include the following.

4,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis (o-methylphenol), 4,4'-secondary butylidene bisphenol 4,4'-isopropylidene bis (2-tert-butylphenol) ), 4,4'-cyclohexylidene diphenol, 4,4'-isopropylidene bis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-Ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tertiarybutyl-2-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tertiary) Ributylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy) -5-Cyclohexylphenyl) butane, 4,4'-thiobis (6-tert-butyl-2)
-Methyl) phenol, 4,4'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl sulfone, 4,4'-diphenol sulfoxide, 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 binding and supporting the leuco dye and the color developer on the support, various conventional binders can be appropriately used, and specific examples thereof include specific examples of the binder that binds the intermediate layer to the support. Selected from among.

Further, in the present invention, various heat fusible substances can be used as the sensitivity improver, and specific examples thereof include the followings, but the present invention is not limited thereto. 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-phenyl naphthoate, 1-hydroxy-2-
Phenyl naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl carbonate, dareyacol 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, dibenzyl disulfide, 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 (4 oxalate)
-Methylbenzyl), bis (4-chlorobenzyl) oxalate and the like.

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

Further, in the present invention, a layer containing a pigment, a binder, a heat-fusible substance and the like can be provided as another intermediate layer between the intermediate layer and the thermosensitive coloring layer, if necessary. Further, in the heat-sensitive recording material of the present invention, a protective layer may be provided on the heat-sensitive color developing layer for the purpose of improving the storage stability of a recorded image or improving the writing property on the recording material. In this case, the above-mentioned pigment, binder, heat-fusible substance or the like can be used as a component constituting the protective layer.

[0020]

EXAMPLES Next, the present invention will be described in more detail by way of examples. All parts and% shown below are based on weight.

The following mixture was stirred and dispersed to obtain an intermediate layer forming liquid. 30% plastic hollow fine particle dispersion liquid 90 parts (styrene-acrylic copolymer, average particle size 3 μm, hollow ratio 50%) 50% styrene-butadiene latex 10 parts The above intermediate layer forming liquid was dried and adhered according to Table 1. In quantity 5.
It was applied and dried so that it would be 0 g / m 2.

Using a magnetic ball mill, a mixture having the following composition was dispersed for (A liquid) for 24 hours so that the average particle diameter was 2.0 μm, and for (B liquid) was dispersed for 15 hours, the average particles were dispersed. The diameter was adjusted to 2.5 μm. (Liquid A) 3-dibutylamino-6-methyl-7-anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts (Liquid B) bisphenol A 20 parts calcium carbonate 10 parts 10% aqueous polyvinyl alcohol solution 30 parts 40 parts of water Next, 20 parts of (Solution A) and 80 parts of (Solution B) are mixed to prepare a thermosensitive color forming layer forming liquid. According to Table 1, the adhering amount after drying on the support or the intermediate layer is 3 After coating and drying so as to have a concentration of 0.5 g / m @ 2 and providing a thermosensitive coloring layer, surface treatment was carried out with a super calendar to prepare a thermosensitive recording material of the present invention.

[0023]

[Table 1]

The following test was conducted on the heat-sensitive recording material produced as described above. The results are shown in Table 2. Dynamic color development sensitivity: Using a simulator printing device manufactured by Okura Electric Co., head power 0.45 W / dot, scanning line density 8 ×
The pulse width is 0.1 to 1.2 under the condition of 7.7 dot / mm.
Printing was performed in 0.1 msec steps up to msec, and the print density was measured with a Macbeth densitometer RD-914, and the energy per dot having a print density of 1.0 was determined. Precision: Using a simulator printing device manufactured by Okura Electric Co., head power 0.45 W / dot, scanning line density 8 ×
A 1-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 reproduced faithfully 4: Dots are reproduced almost faithfully 3: Dots can be identified but are slightly faint 2: Dots are faint and missing in some places 1: Dots are faint Can not

[0025]

[Table 2] It can be seen from Table 2 that the examples are excellent in both dynamic color development sensitivity and fineness. Further, it is found that the combined use of the hollow plastic particles results in higher sensitivity, and the use of the rubber coating layer having a rubber hardness of 100 or less results in higher fineness.

[0026]

As described above, according to the present invention, by providing the support with the vulcanized rubber coating layer, it is possible to obtain a heat sensitive recording material having high sensitivity and excellent fineness.

Claims (3)

[Claims] 1. A heat-sensitive recording material comprising a support, the surface of which is covered with vulcanized rubber, and a thermosensitive coloring layer comprising at least a leuco dye and a color developer provided on the support. 2. The heat-sensitive recording material according to claim 1, wherein an intermediate layer containing hollow plastic particles is provided between the support coated with the vulcanized rubber and the heat-sensitive recording layer. 3. The coating layer made of vulcanized rubber,
2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording material is formed of a rubber having a rubber hardness of 100 or less measured by a measuring method specified in JIS K6301.