JPH11180040A - Heat-reactive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording material with good color developing texture in a thermal recording material prepd. by providing an intermediate layer contg. non-foamable fine hollow particles between a substrate and a heat- sensitive color developing layer, the heat-sensitive color developing layer thereon and furthermore, if necessary, an over layer. SOLUTION: In a recording medium wherein an intermediate layer contg. plastic fine hollow particles with a hollow rate of at least 80% and a heat- sensitive recording layer developing color by heat at successively provided on a substrate, the relation between the thickness r1 of the intermediate layer and the max. particle diameter r2 of the plastic fine hollow particles is 2r1 >r2 or the relation between the thickness r1 of the intermediate layer and the max. particle r2 of the plastic fine hollow particles is r1 >r2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer output, a printer such as a calculator, a recorder for medical measurement, a low-speed and high-speed facsimile, a vending machine, a thermal copying machine, a label for a POS system, and the like. The present invention relates to a heat-sensitive recording material which is widely used.

[0002]

2. Description of the Related Art In recent years, with the diversification of information and the expansion of needs, various recording materials have been studied, developed, and put into practical use in the information recording field. (2) It has the advantages that the required mechanism of the device is simple and compact, and that the recording material is easy to handle and inexpensive. In recent years, demand for this heat-sensitive recording material in various fields has been expanding, and higher performance (small size, high speed) of devices has been further demanded. Therefore,
There is a demand for heat-sensitive recording materials that have high sensitivity and high definition in response to a reduction in printing energy due to miniaturization and high speed of the apparatus.

[0003] A thermosensitive recording material is usually produced by coating a thermosensitive coloring layer solution containing a coloring component capable of causing a coloring reaction upon heating on a support such as paper or a synthetic resin film and drying the coating. The thus obtained thermosensitive recording material is heated with a hot pen or a hot head to form a color image. As a conventional example of such a heat-sensitive recording material, there is a heat-sensitive recording material disclosed in, for example, JP-A-43-4160 or JP-B-45-14039. Responsiveness was low, and sufficient color density could not be obtained during high-speed recording. As a method for improving such a defect, for example, Japanese Patent Publication No. 49-38424 discloses a nitrogen-containing compound such as acetamide, stearamide, m-nitroaniline, and dinitrile phthalate. The anilide acetate is used in JP-A-53-11036.
JP-A-53-39 discloses N, N-diphenylamine derivatives, benzamide derivatives and carbazole derivatives.
No. 139 discloses an alkylated biphenyl and a biphenyl alkane, and JP-A-56-144193 discloses a method for increasing the speed and sensitivity by adding a p-hydroxybenzoic acid ester derivative. However, no satisfactory results were obtained by any of the methods.

In addition, fillers such as calcium carbonate, clay and urea-formalin resin are usually added to the heat-sensitive coloring layer in order to maintain whiteness of the background, to prevent adhesion of head scum, to prevent sticking, etc. In general, a water-soluble resin is added for fixing the additive to the support. Further, in order to increase the density of the color-forming components, it is preferable that these are as small as possible. However, reducing the content of these additives causes deterioration of the print quality of the thermosensitive color image.

As another method for achieving high density and high definition, there is a method for increasing the smoothness of the surface of the thermosensitive coloring layer. This can be easily achieved by calendering with a super calender or the like. Specifically, a calendering process is performed so that the density of the heat-sensitive recording material is 0.85 g / cm ² or less and the Beck smoothness of the surface of the heat-sensitive coloring layer is 1000 seconds or more (Japanese Patent Application Laid-Open No. 64-30783). Publication). However, if excessive calendering is performed to improve the smoothness, background fogging will occur and the appearance of the recording paper will be impaired. Therefore, as a method for obtaining a high-sensitivity, high-definition thermosensitive recording material without impairing other properties such as sticking or head matching, background whiteness, heat-resistant storage stability, as disclosed in JP-A-64-30785. There is a method in which an intermediate layer having a foamable plastic filler is provided between a support and a thermosensitive coloring layer, and after heat foaming, calendering is performed so that the surface of the intermediate layer has a Beck smoothness of 2000 or more. But with this method,
A calendering process is performed for each of the intermediate layer and the thermosensitive coloring layer, which complicates the process and is inconvenient.

Another method is to use various kinds of minute hollow particles (resin, glass, aluminosilicate type, etc.) on an intermediate layer on a support (JP-A-59-5093 and JP-A-5-50993).
However, in these cases, it is difficult to form a uniform intermediate layer, and the surface tends to be non-uniform, so that the formed image has high definition (dot reproducibility).
Was a problem. Further, a styrene-acrylic resin and a polystyrene resin may be used as the partition wall material of the fine hollow particles (JP-A-63-281886), or a hollow layer mainly composed of non-foamable fine hollow particles having a hollow ratio of 30% or more. (Japanese Unexamined Patent Application Publication No. 2-214688)
Japanese Patent Application Laid-Open No. H11-157, 1993, has also been proposed, however, because these materials have a low hollow ratio, a sufficient heat insulating effect cannot be obtained, and a high-sensitivity heat-sensitive recording material that is currently required has not been obtained.

Further, an average particle diameter of 2 to 10 μm
In addition, a method has been proposed in which minute hollow particles having a hollow ratio of 90% or more are used for an intermediate layer (Japanese Patent Application Laid-Open No. H4-2241987). However, such minute hollow particles contain a small amount of giant particles, which are considerably larger than their average particle diameter, and they are very difficult to detect by ordinary particle diameter measurement. Therefore, in the past, there was no technique for making giant particles contained in a small amount symmetrical. However, the presence of a small amount of giant particles causes unevenness on the surface of the intermediate layer containing the giant particles, leading to non-uniformity of the thermosensitive coloring layer applied thereon. Especially,
When the particle diameter of the giant particles is much larger than the thickness of the intermediate layer, a large convex portion is formed where the giant particles are present, and the thermosensitive coloring layer formed thereon cannot be uniformly formed. However, there is a problem that a non-colored portion (white dropout portion) is generated on the surface, and the color formation is significantly deteriorated.

[0008]

According to the present invention, an intermediate layer containing non-foamable fine hollow particles is provided between a support and a thermosensitive coloring layer, and a thermosensitive coloring layer and, if necessary, an overlayer are provided thereon. An object of the present invention is to provide a heat-sensitive recording material having good color formation.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a drastic countermeasure for giant particles contained in a small amount in non-expandable fine hollow particles which cause a formation mismatch. As a result of examining the elimination of the unevenness existing on the evaluation surface of the intermediate layer, the following means have been derived.

According to the present invention, the hollow ratio is 80% on the support.
An intermediate layer containing the above plastic fine hollow particles,
In a recording medium provided with a heat-sensitive recording layer which sequentially develops color by heat, the relationship between the layer thickness (r ₁ ) of the intermediate layer and the maximum particle diameter (r ₂ ) of the hollow plastic microparticles is 2r ₁ > r ₂ . Thus, the above problem can be solved.

According to the present invention, the thickness of the intermediate layer (r
The relationship between ₁ ) and the maximum particle (r ₂ ) of the plastic fine hollow particles is that r ₁ > r ₂ , and the plastic fine hollow particles contained in the intermediate layer have a hollow ratio of 50% or more, and the average particle size The mixture of different plastic micro hollow particles, the ratio of the average particle diameter of the plastic micro hollow particles having different average particle diameters contained in the intermediate layer is 1: 0.8 or less, and The above problem can be solved by the addition ratio (weight ratio) of the plastic fine particle diameters having different average particle diameters contained in the range of 1: 0.5 to 1: 3. If the use ratio of the fine hollow particles is less than this, the effect of improving the formation is often not improved, and if the use ratio is too large, other quality problems such as a decrease in sensitivity may occur.

In the present invention, the leuco dye used in the heat-sensitive coloring layer is applied alone or as a mixture of two or more kinds. As such a leuco dye, those applied to this kind of heat-sensitive material are used. Optionally applied, 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 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-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 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) 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-dipentylamino-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-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'-benzofluoran, 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-
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-
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-dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane, and the like.

In the present invention, various electron-accepting compounds, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, thiourea derivatives, organic acids and metal salts thereof, are used as a color developer to develop the leuco dye upon contact. 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-tertiary) 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-tert-butylphenyl) butane, 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, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuylate, 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′-diphenolsulfone, 3,3′-diallyl-4,4′-diphenolsulfone, α, α-bis (4-hydroxy Phenyl) -α-methyltoluene,
Tetrabromobisphenol A, tetrabromobisphenol S, 4,4′-thiobis (2-methylphenol), 4,4′-thiobis (2-chlorophenol),
etc.

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

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;
Fatty acid metal salts such as calcium stearate, zinc palmitate, zinc behenate, p-benzylbiphenyl, m
-Terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl carbonate , Dareiacol carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-ethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 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-aryloxybiphenyl, 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 (4-methylbenzyl) oxalate, 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, pressure coloring. An inhibitor or 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,
In addition to inorganic fine powders such as talc and surface-treated calcium and silica, organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, and vinylidene chloride resin can be given. Examples of the lubricant include higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, various kinds of 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 may be provided with a protective layer on the heat-sensitive coloring layer of the present invention for the purpose of improving the head matching property at the time of printing, and improving the writing property and the marking property on the recording material. Yes, but in this case,
As the components constituting the protective layer, the above-mentioned pigments, binders, heat-fusible substances and the like can be used.

[0021]

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

<Removal of Large Particles from Plastic Micro Hollow Particles> The plastic micro hollow particles are converted into various kinds (different mesh sizes) of mesh (nylon mesh or metal mesh) or a filtration device (W-CELL filter:
Filtration (classification) using Arai Iron Works) to remove large particles. At this time, the size of the mesh or the size of the opening of the filtration device is the maximum particle size r ₂ . (Actually, filtration will remove particles larger than r ₂ .

<Preparation of Intermediate Layer Forming Liquid> 100 parts of plastic fine hollow particle dispersion (identical concentration 20% described in Table 1) Styrene / butadiene copolymer latex (solid content 40%) 25 parts 10% aqueous solution of polyvinyl alcohol 20 parts 15 parts of water (20% under liquid of the same shape) A mixture composed of the above-mentioned intermediate layer forming liquid was mixed and stirred to prepare an intermediate layer coating liquid. This was coated and dried on the surface of a commercially available high-quality paper (basis weight: 60 g / m ² ) so that the amount of adhesion and the layer thickness after drying would be the values shown in Table 1, thereby producing paper coated with an intermediate layer.

<Preparation of Liquid for Forming Thermosensitive Recording Layer> (Dispersion A) 3- (N, N-di-n-butyl) amino-6-methyl-
7-anilinofluorane 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 33 parts (Dispersion B) 4-hydroxy-4'-isopropoxydiphenyl sulfone 10 parts Silica 10 parts Polyvinyl alcohol 10% aqueous solution 25 parts Water 30 parts Dispersions A and B were prepared by dispersing the mixture having the composition using a sand mill so that the average particle diameter was 2 μm or less. (Preparation of Thermosensitive Layer Forming Liquid) Dispersion A 6.3 parts Dispersion B 40 parts Zinc stearate dispersion (solid content concentration 30%) 3 parts

The heat-sensitive layer forming liquid prepared as described above was prepared. After applying a coating amount adjustment such as a solid content adjustment so that the dry adhesion amount of the leuco dye becomes 0.5 g / m ^{2 on} the surface of the paper on which the intermediate layer has been applied, the resultant is coated and dried to provide a thermosensitive coloring layer. Then, a super calender treatment was performed so that the Beck smoothness became 500 to 600 seconds to obtain a heat-sensitive recording material of the present invention.

Elcos Stamprint SP-30F
And color development by heating was performed, and the color formation was visually evaluated. ◎: very good (uniform formation without unevenness) ：: good (slightly uneven but not noticeable) △: bad (conspicuous unevenness) ×: very bad (white spots are generated)

[0027]

[Table 1]

[0028]

As apparent from the detailed and specific explanations above, it can be seen that the heat reflection type recording medium of the present invention is extremely excellent in coloring and formation.

Claims (5)

[Claims] 1. A recording medium in which an intermediate layer containing plastic fine hollow particles having a hollow ratio of 80% or more and a heat-sensitive recording layer colored by heat are sequentially provided on a support, and the layer thickness (r ₁ ) of the intermediate layer And a maximum particle diameter (r ₂ ) of the hollow plastic fine particles is 2r ₁ > r ₂ . 2. In a recording medium in which an intermediate layer containing plastic fine hollow particles having a hollow ratio of 80% or more and a heat-sensitive recording layer which develops color by heat are sequentially provided on a support, the layer thickness (r ₁ ) of the intermediate layer _3. The heat-reactive recording medium according to claim ₁ , wherein the relationship between the maximum particle size (r ₂ ) of the plastic fine hollow particles is r ₁ > r ₂ . 3. The plastic fine hollow particles contained in the intermediate layer and the plastic fine hollow particles have a hollow ratio of 50%.
3. The heat-reactive recording medium according to claim 1, wherein the medium is a mixture with plastic fine hollow particles having different average particle diameters by% or more. 4. The plastic fine hollow particles having different average particle diameters contained in the intermediate layer have a ratio of the average particle diameter of 1:
The heat-reactive recording medium according to claim 3, wherein the ratio is 0.8 or less. 5. The method according to claim 4, wherein the addition ratio (weight ratio) of the plastic fine hollow particles having different average particle sizes contained in the intermediate layer is 1: 0.5 to 1: 3. The heat-reactive recording medium according to the above.