JPH04221684A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a heat sensitive recording material not generating the so- called sticking phenomenon such that the components in a heat sensitive color forming layer are melted at the time of thermal printing to be bonded to a thermal pen or a thermal head and imparting a sharp color image. CONSTITUTION:A color forming layer using a developer whose mean particle size in a microtrack is 1.0mum or less and bisphenol A whose 20% or less has a particle size of 2.0mum or more is provided on a support.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a heat-sensitive recording material, and more specifically, the present invention relates to a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye that is colorless or light-colored at room temperature and a color developer for the leuco dye, to improve the sticking phenomenon. It is related to.

0002

[Prior Art] Heat-sensitive recording materials, such as thermal paper, are usually coated with a heat-sensitive coloring layer containing a coloring component that can cause a coloring reaction when heated, on a support such as paper, synthetic paper, or synthetic resin film. It is manufactured by drying, and a colored image is recorded by heating it with a thermal pen or thermal head. When these heat-sensitive recording materials are heated to develop color, the components in the heat-sensitive color layer melt and stick to the thermal pen or thermal head (so-called sticking phenomenon), resulting in a decrease in the density and sharpness of the colored image. This method has disadvantages in that it tends to cause distortion of the colored image, inconvenience in paper feeding, and abrasion of the thermal pen or thermal head. As a method for improving such drawbacks, there have been many disclosures of using highly oil-absorbing inorganic or organic fillers in the recording layer.
I still haven't gotten anything I'm satisfied with.

0003

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material that improves the above-mentioned conventional drawbacks, namely, to improve the sticking phenomenon of sticking to a thermal pen and thermal head during thermal printing. The object of the present invention is to provide a heat-sensitive recording material with a high temperature.

0004

[Means for Solving the Problems] According to the present invention, in a heat-sensitive recording material in which a coloring layer containing a leuco dye and a color developer as main components is provided on a support, the color developer is Particle size is 1.0 μm or less and 2.0 μm
Provided is a heat-sensitive recording material characterized by using bisphenol A containing 20% or less of m or more. Although it is very common to use bisphenol A as a color developer, it is also well known that it is prone to sticking. Although the cause of this sticking has not necessarily been determined, one cause is thought to be that the melting-cooling-solidification cycle during heating is fast and the material solidifies without being absorbed by the filler or the like. Therefore, just using a large amount of oil-absorbing filler or using a filler with a large oil-absorbing amount as in the past was not sufficient to solve the sticking problem. As a result of intensive studies on the sticking of heat-sensitive recording materials using bisphenol A, the present inventors found that in order to promote absorption during melting, the average particle size was reduced to 1 μm or less using microtracks, and particles of 2.0 μm or more were It was found that the problem can be solved by reducing the amount to % or less.

The size of this bisphenol A is considered to correspond to the amount that can be instantly absorbed by the oil-absorbing filler. Naturally, sticking will occur if the amount of bisphenol A, etc., which is obtained by melting the oil-absorbing filler, is not added in an amount sufficient to completely absorb the oil-absorbing filler.

[0007] The leuco dyes used in the present invention may be applied singly or in combination of two or more types. As such leuco dyes, those applied to this type of heat-sensitive material can be arbitrarily applied. For example, Leuco compounds of dyes such as triphenylmethane, fluoran, phenothiazine, auramine, spirohyran, and indolinophthalide 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- Chlorphthalide, 3,3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7-dimethylfluoran,
3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-
6-Methyl-7-chlorofluorane, 3-(N-p-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)xantylbenzoic acid lactam}, 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 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-cyclohexyl Amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(
N,N-diethylamino)-5-methyl-7-(N,N
-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2
'-Hydroxy-4'-dimethylaminophenyl)-3
-(2'-Methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3-(2'-methoxy-5'-nitrophenyl)phthalide, '-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)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran,
3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(pn
-butylanilino)fluoran, 3-(N-benzyl-
N-cyclohexylamino)-5,6-benzo-7-α
-Naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino-4', 5'
-benzofluorane, 3-diethylamino-6-methyl-7-(2',4'-dimethylanilino)fluoran, etc.

[0008] Furthermore, as the color developer that can be used in combination with bisphenol A in the present invention, conventionally known color developers can be used. Specific examples include inorganic acids, organic acids,
Examples include phenolic substances and phenolic resins. Bentonite, zeolite, acid clay, activated clay, silica gel, phenolic resin, 4,4'-isopropylidene bis(o-methylphenol), 4,4'-secondary butylidene bisphenol 4,4'-isopropylidene bis(o- 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-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-cyclohexylphenyl)butane, 4,4'-thiobis(6
-tert-butyl-2-methyl)phenol, 4,
4'-Diphenolsulfone, 4,2'-diphenolsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenolsulfoxide, P- Isopropyl 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, 2,2
'-methylenebis(4-ethyl-6-tert-butylphenol), 1,3-bis(4-hydroxyphenylthio)-2-hydroxypropane, N,N'-diphenylthiourea, N,N'-di(m -chlorophenyl)thiourea, salicylanilide, 5-chloro-salicylanilide, salicyl-o-chloroanilide, 2-hydroxy-
3-naphthoic acid, antipyrine complex of zinc thiocyanate, zinc salt of 2-acetyloxy-3-naphthoic acid, 2-
Hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum, calcium, etc. 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-hydroxyphenyl)-α-
antipyrine complex of methyltoluene zinc thiocyanate,
Tetrabromobisphenol A, tetrabromobisphenol S, 3,4-dihydroxy-4'-methyldiphenylsulfone, etc.

In the present invention, when a leuco dye and a color developer are bonded and supported on a support in order to obtain a heat-sensitive recording material, various conventional binders can be used as appropriate. Specific examples of such binders include the following.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, polysodium acrylate, polyvinylpyrrolidone, acrylamide/acrylic acid ester copolymer, acrylamide/acrylic acid ester In addition to water-soluble polymers such as /methacrylic acid terpolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc. Emulsions such as vinyl acetate, polyurethane, polyacrylic ester, polymethacrylic ester, vinyl chloride/vinyl acetate copolymer, ethylene/vinyl acetate copolymer, styrene/butadiene copolymer, styrene/butadiene/acrylic copolymer Latex such as coalescence, etc.

[0011] Furthermore, when obtaining a heat-sensitive recording material according to the present invention, various heat-fusible substances can be used as a heat sensitivity improver, if necessary. Specific examples thereof include the following compounds. It will be done. 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 ester, 1-hydroxy-2-naphthoic acid Phenyl ester, 1-hydroxy-2-naphthoic acid methyl ester, diphenyl carbonate, terephthalic acid dibenzyl ester, terephthalic acid dimethyl ester, 1,4-dimethoxynaphthalene, 1
, 4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-bis(phenoxy)ethane, 1
, 2-bis(3-methylphenoxy)ethane, 1,2-
Bis(4-methylphenoxy)ethane, 1,4-bis(
phenoxy)butane, 1,4-bis(phenoxy)-2
-butene, 1,2-bis(4-methoxyphenylthio)
Ethane, dibenzoylmethane, 1,4-bis(phenylthio)butane, 1,4-bis(phenylthio)-2-butene, 1,2-bis(4-methoxyphenylthio)ethane, 1,3-bis(2 -vinyloxyethoxy)benzene, 1,4-bis(2-vinyloxyethoxy)benzene, p-(2-vinyloxyethoxy)biphenyl, p
-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyl disulfide, 1,
1-diphenylethanol, 1,1-diphenylpropanol, p-(benzyloxy)benzyl alcohol,
1,3-diphenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, etc.

In addition, in the present invention, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as
Fillers, surfactants, lubricants, pressure coloring inhibitors, etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. Examples of lubricants include higher fatty acids and their metal salts, higher fatty acid amides, higher fatty acid esters, and animal-based , various vegetable, mineral, or petroleum waxes. The heat-sensitive recording material of the present invention can be used in various fields like conventional ones, but in particular, by utilizing its excellent near-infrared light absorption properties, it can be used in optical character reading devices,
It can be used as a recording material for label barcode readers and barcode reader record reading.

The heat-sensitive recording material of the present invention can be produced by, for example, applying a coating liquid for forming a heat-sensitive layer containing the above-mentioned components onto a support such as paper, synthetic paper, or plastic film, drying it, and subjecting it to a calender treatment. It is obtained by In this case, it is also possible to provide an undercoat layer below the thermosensitive coloring layer and an overcoat layer above it. The amounts of leuco dye, color developer and other auxiliary additives used are 5 to 40% by weight and 20% by weight, respectively.
-60% by weight, 20-60% by weight is suitable.

[0014]

[Effects] The heat-sensitive recording material of the present invention has excellent dynamic coloring properties and is extremely practical as it eliminates the sticking problem that occurs when bisphenol A is used.

[0015]

EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples. Note that all parts and percentages shown below are based on weight.

Example 1 A mixture having the following composition was ground for 2 to 5 hours using a sand mill to prepare liquids [A] and [B], respectively. [A] Liquid 3-dibutylamino-6'-methyl-7-
Anilinofluorane 20 parts 10%
Polyvinyl alcohol aqueous solution
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water

60 parts [B] Liquid 1,2-bis(3,4-dimethylbenzene) 25 parts
10% polyvinyl alcohol

Part 25 Water

50 parts Next, a bisphenol A dispersion (liquid [C]) having the following composition was ground for 4 hours using the same sand mill. The average particle size of bisphenol A after crushing in Microtrack is 0.9
The percentage of particles larger than 2.0 μm was 12%. [C] Liquid Bisphenol A

25 parts 10% polyvinyl alcohol
Part 25 Water


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Next, a heat-sensitive coating liquid was prepared with the following composition, and after coating and drying on high-quality paper with a basis weight of 47 g/m2 until the dry coating amount became 5.0 g/m2,
The thermosensitive recording paper of the present invention was obtained by calendering. [A] Liquid

10 parts [B] Liquid

20 parts [C] Solution

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Calcium carbonate (manufactured by Shiroishi Central Research Institute: Callite KT)
) 10 parts silicon oxide (Mizusawa Chemical: Mizukashiru P-832)
Part 5 Water


35 copies

Example 2 [C] in Example 1
A thermosensitive recording paper of the present invention was obtained in the same manner except that the liquid pulverization time was changed to 8 hours. At this time, the average particle size of bisphenol A was 0.8 μm, and 4% of the particles were 2.0 μm or more.

Example 3 A thermosensitive recording paper of the present invention was obtained in the same manner as in Example 1 except that 10 parts of Hydrin F-568, a bisphenol A dispersion manufactured by Chukyo Yushi Co., Ltd., was used in place of liquid [C] in Example 1. The average particle size of bisphenol A at this time was 0.9 μm, 2.0
Particles larger than μm accounted for 6%.

Comparative Example 1 A comparative thermosensitive recording paper was obtained in the same manner as in Example 1, except that the grinding time of liquid [C] was changed to 2 hours. The average particle size of bisphenol A at this time was 1.1 μm and 2.0 μm.
The proportion of particles larger than m was 28%.

Comparative Example 2 In place of Hydrin F-568 in Example 3, bisphenol A dispersion Hydrin F-, also manufactured by Chukyo Yushi Co., Ltd.
A thermal recording paper for comparison was obtained in the same manner except that 285 was used. The average particle size of bisphenol A at this time was 1.2μ
24% of the particles were 2.0 μm or larger.

Comparative Example 3 A comparative thermal recording paper was obtained in the same manner as in Comparative Example 1 except that benzyl p-hydroxybenzoate was used instead of bisphenol A. The average particle size of benzyl p-hydroxybenzoate at this time was 1.2 μm, and 24% of the particles were 2.0 μm or more.

The following quality evaluations were carried out using the thermal recording paper of the present invention and the comparative thermal recording paper obtained as described above. The results are shown in Table 1. (1) Dynamic coloring property: Head power 0.45 using a thermal printing experimental device with a thin film head manufactured by Matsushita Electronic Components Co., Ltd.
w/dot, 1 line recording time 20ms/line, scanning line density 8 x 3.85 dots/mm, and print with pulse widths of 0.2, 0.6, and 1.0msec, and the print density is Macbeth density. Measured using RD-914. (2) Sticking: After 200 lines of black solid printing with a pulse width of 1.0 ms using the same thermal printing experimental device, a stop time of 320 msec was repeated 5 times to confirm the presence or absence of sticking.

[0024]

[Table 1]

As is clear from Table 1, the heat-sensitive recording material of the present invention has no sticking compared to the comparative heat-sensitive recording material, and is therefore extremely useful.

Claims (1)

[Claims] Claims: 1. A heat-sensitive recording material comprising a coloring layer containing a leuco dye and a color developer as main components on a support, wherein the color developer has an average particle size in microtrack of 1.0 μm or less; A heat-sensitive recording material characterized by using bisphenol A containing 20% or less of bisphenol A having a diameter of 2.0 μm or more.