JPS63280683A - Thermal recording material - Google Patents

Abstract

PURPOSE:To improve dot reproducibility by building a thermal color development layer with a density of 0.7g/cm<2> or less on a primer layer consisting mainly of pigment and binder on a support to form a thermal recording material. CONSTITUTION:A primer layer consisting mainly of pigment and binder is provided on a support, and on this primer layer, a thermal color development layer with a density of 0.7g/cm<2> is built on the primer layer to form a thermal recording material. As pigments used for the primer layer, calcium carbonate with an oil absorption degree of 40cc/100g or more, pulverized urea formalin resin, etc. which are prescribed by JIS-K5101 are used. As color development agents, triaryl methane compound, diphenyl methane compound, xanthene compound, thiazine compound, spiropyran compound, etc. are used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material in which a heat-sensitive color forming layer is provided on a support having an undercoat layer.

(Prior Art) Regarding heat-sensitive recording, many methods have been known for a long time.For example, a heat-sensitive recording material using an electron-donating dye precursor and an electron-accepting compound is disclosed in Japanese Patent Publication Akihiro J-/440#.
It is disclosed in No. 3, Tokuko Sho≠3-Hiroshi/No. 60, etc. Further, a heat-sensitive recording material using a diazo compound is disclosed in Japanese Patent Application Laid-Open No. 2003-111002. In recent years, these thermal recording systems have been applied to a wide range of fields such as facsimiles, printers, and labels, and the needs for them are expanding. with this,
Characteristics that have not been required in the past have become increasingly required for thermosensitive recording. One of these is the reproducibility of printed dots. Generally, printing is performed on thermal recording paper by heating it with a minute heating element of about 100 μm x xoo μm called a thermal head. At this time, the ability to faithfully reproduce the shape of the minute heating element as an excitation element is the key to high print quality. I've come to understand that there is one thing you need to do to get it. This is called print dot reproducibility.

(Object of the Invention) An object of the present invention is to provide a heat-sensitive recording material with good dot reproducibility and high printing quality.

(Structure of the Invention) An object of the present invention is to provide a heat-sensitive recording material in which an undercoat layer containing a pigment and a binder as main components is provided on a support or carrier, and a heat-sensitive coloring layer is provided on the undercoat layer. This was achieved using a heat-sensitive recording material characterized by a density of 0.7777 cm3 or less. An example of providing a heat-sensitive coloring layer on a support provided with an undercoat layer is given in JP-A-Sho! tar lb bow 1
The present inventors have developed a thermosensitive coloring layer I8! degree is 0
, 7 fl/cm3 or less, it has been found that a heat-sensitive recording material with specifically good dot reproducibility can be obtained.

In this specification, the density of the heat-sensitive coloring layer is defined as the density of the heat-sensitive coloring layer coating 1. ! It is expressed as the value (F/Cm) obtained by dividing i'/m) by the fabric thickness (μm) of the thermosensitive coloring layer. The coating thickness is determined by observing a vertical section of the heat-sensitive recording material using an electron microscope, measuring the cross-sectional area using an image analysis device, and calculating the cross-sectional area divided by the length of the observed surface.

Pigments that can be used in the undercoat layer of the present invention are JTS-Kj/
The oil absorption defined by 0 / is ≠Qcc7toog or more, and organic or inorganic pigments can be used. Preferred examples include calcium carbonate, barium sulfate,
Examples include titanium oxide, Merck, waxite, kaolin, calcined kaolin, aluminum hydroxide, amorphous silica, urea-formalin resin powder, polyethylene resin powder, and the like.

Examples of the binder used in the undercoat layer include water-bathable polymers and water-insoluble binders, and binders may be used in combination of 1 or λ or more types.

Examples of water-bathable polymers include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride hydrolyzate, ethylene-maleic anhydride hydrolyzate, and Butylene-maleic anhydride copolymer hydrolyzate, polyvinyl alcohol,
Examples include carboxy-modified polyvinyl alcohol and polyacrylamide.

As the water-insoluble binder, synthetic rubber latex or synthetic resin emulsion is generally used, and examples include styrene-butadiene rubber latex, acrylonitrile-getadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion. .

The amount of binder used is 3 to 100 inches per pigment, preferably! ~, roqb.

The undercoat layer contains thermofusible substances such as wax and anti-fading agents,
A surfactant or the like may be added.

Next, a typical method for producing a heat-sensitive coloring layer of the present invention will be described.

For example, in a system using an electron-donating dye precursor (hereinafter referred to as a color former) and an electron-accepting compound (hereinafter referred to as a color developer), the color former and color developer are separately processed using a ball mill, sand mill, etc. A heat-sensitive coating liquid can be obtained by dispersing the particles to a size of several microns or less and mixing them.

Color formers and color developers are generally dispersed together with a water bathing polymer such as polyvinyl alcohol, and if necessary, a sensitizer can also be dispersed and added. The sensitizer may be added to either or both of the color former and the color developer and may be dispersed simultaneously.

After dispersion, these dispersions are mixed, the oil-absorbing pigment of the present invention is added, and if necessary, a surfactant, a binder,
Add wax, metallic soap, antioxidant, ultraviolet absorber, etc. to make a heat-sensitive coating liquid.

The obtained heat-sensitive coating liquid is coated on the above-mentioned undercoat layer and dried, and then subjected to a calendering process to impart smoothness to the desired heat-sensitive recording material.

Examples of the coloring agent used in the present invention include tria IJ-rumethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, and spiropyran thread compounds. To illustrate some of these, 3.3-
Bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e. crystal violet lactone)
, 3.3-bis(p-dimethylaminophenyl J phthalide, 3-(≠-dimethylamino-2-ethoxyphenyl)-J-(/-ethyl-methylindol-3-yl)phthalide, 3-(ILt -dietheramino-ethoxyphenyl)-3-(/-octyl-comethylindol-3-yl) phthalide, etc. Diphenylmethane thread compounds include french, μ'-bis-dimethylaminobenzhydrin benzyl ether, There are he-halophenyl leuco auramine, he λ, ≠+zb'J1-halophenyl leuco auramine, etc., and xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine B ( p
-chloroanilino)lactam, colabenzylamino-
t-diethylaminofluorane, 2-anilino-ot-diethylaminofluorane, λ-anilino 3-methyl-
6-ethylaminofluorane, λ-anilino-3-methyl-j-N-cyclohequine-methylabanofluorane, 3. t-bisdiphenylaminofluorane, co-anilino 3-methyl-J-N-ether-~-isoamylaminofluorane, co-0-chloroanili/-A-
Diethylaminofluorane, um-chloroanilino-
6-diethylaminofluorane, λ-(3,≠-dichloroanilino)-6-diethylaminofluorane, co-octylamino-t-diethylaminofluorane, co-ophexylamino-6-diethylaminofluorane, λ-
m-trichloromethylanilino-6-diethylaminofluorane, co-optylamino-3-ri-o-4-diethylaminofluoran, co-ethoxyethylamino-3-chloro-6-diethylaminofluorane, co-anilino-3-chloro- -diethylaminofluorane, co-phenylamino-4-diethylaminofluorane,
λ-anilino 3-methyl-6-siphenylaminofluorane, j-7 anilino 3-methyl-! -Kuroro 2-
Diethylaminofluoran, λ-anilino 3-methyl-6-dinitylamino-7-methylfluoran, co-anilino 3-methoxy 2-dibutylaminofluoran 1.2-o-chloroanilino-6-sibutylaminofluoran, J-p- Chloroanilino-3-ethoxy-6-
diethylaminofluorane, co-phenyl-&-diethylaminofluorane, co-0-chloroanilino-4-
p-Butylanilinofluorane, -1-anilino-3-pentaden-6-diethylaminofluorane, co-anilino-3-ethyl-t-digtylabanofluorane, co-anilino-3-ethyl-4-N-ethyl-he-1-ineamylaminofluorane, λ -anilino-3-methyl-t
-h-ethyl-N-r-methoxypropylaminofluorane, co-anilino-3-phenyl-t-diethylaminofluorane, co-ethylamino-3-phenyl-t
-diethylaminofluorane, co-anilino-3-methyl-4-N-ynamyl-he-dithylaminofluorane, etc. Thiazine compounds include benzoylleucomethylene blue, p-nitrobenzylleucomethylene blue, etc., and spiro compounds include Is 3-methyl-spirogi f7 tobiran, 3-ethyl-spirogi? 7
) pyran, 3.3'-dichlorospirodi f7 tobiran, 3-benzylspiro-cinna7 topyran, 3-methyluna 7)-1-methoxy-benzo)-spiropyran, 3
-propyl-spiro-dibenzopyran and the like. These may be used alone or in combination to adjust hue or improve image preservation.

As the color developer used in the present invention, Co, Corbis (4t
/-Hydroxyphenyl)propane (bisphenol A
), Co, Corbis(Hiro-Hydroxyphenyl)intane, Co, Corbis(Hiro'-Hydroxy-31.11-dichlorophenyl)furopane, 1. l-bis(≠'-hydroxyphenyl)cyclohexane, co, corbis(4t'
-hydroxyphenyl)hexane, /, /-bis(v
'-Hydroxyphenyl)propane, t,t-bis(3'-hydroquinphenyl)butane, i,t-bis(≠/
e troxyphenyl) is tanthane, /, /-bis(
μ′-hydroxyphenyl)hexane, 1Il-bis(
4t/-hydroquinphenyl)hebutane, l#l-bis(4L/-hydroxyphenyl)octane, /, /-
Bis(≠-hydroxy-7enyl)-comethyl-pentane, /, /-bis(≠-hydroxyphenyl-2-
Ethyl-hexane, /, /-bis(p-hydroxyphenyl)totican, /, 4L-bis(p-hydroxyphenylcumyl)benzene, 1,3-bis(p-hydroxyphenylcumyl)benzene, bis( p-hydroxyphenyl) sulfone, bis(3-allyl-≠-hydroxyphenyl) sulfone, bis(p-hydroquinphenyl)
112 Benzyl esters of bisphenols, 3, j-di-α-methylbenzyl salicylic acid, 3,! −
Salicylic acids such as di-tertiarybutylsalicylic acid, 3-α,α-dimethylbenzylsalicylic acid, ≠-(β-p-methoxyphenoquinethoxy)salicylic acid, or polyvalent metal salts thereof (preferably zinc and aluminum in %), Oxybenzoic acid esters such as p-hydroxybenzoic benzyl ester, p-hydroxybenzoic m-λ-ethylhexyl ester, β-resorcinic acid-(2-phenoxyethyl) ester, p-7-phenol,
3. Examples include phenols such as j-diphenylphenol and cumylphenol, and bisphenols are particularly preferred.

As the sensitizer added to the thermosensitive coloring layer, general formula (I)
Examples include compounds represented by (IV). The sensitizers may be used alone or in combination.

Otsu R3C0NHR4 (ITIN formula R1%R2, R3 is an alkyl group or an aryl group,
R4 represents a hydrogen atom, an alkyl group, or an aryl group, R5 represents a divalent group, and A and B may be the same or different (,0
, C02 or S, X, Y, Z1 , represents an alkylthio group.

Further, X and Y, or X' and Y' may consecutively form a ring.

In addition, the alkyl group represents a saturated or unsaturated alkyl group or a cycloalkyl group, and these include an aryl group, an alkoxy group, an aryloxy group, a 10-gen atom, an acylamino group, an aminocarbonyl group, or a cyano group.
The aryl group may have a substituent, and the aryl group represents a phenyl group, a naphthyl group, or a heteroaromatic group;
gun atom, nitro group, cyano group, am carbamoyl group,
Substituents such as a substituted sulfamoyl group, a substituted amino group, a substituted oxycarbonyl group, a substituted oxysulfonyl group, a thioalkoxy group, an arylsulfonyl group, or a phenyl group may also be included.

In the above formula, among the groups represented by R1, R2, R3, and R4, an alkyl group having 1 to 10 carbon atoms which may have an e substituent and a substituent having 6 to 0 carbon atoms are An aryl group which may have one is preferable, and the substituent is preferably an aryl group, an alkyl group, an alkoxy group, an aryloxy group, a halogen atom, etc. Among the groups represented by R5,
An alkylene group, an alkylene group having an ether bond, an alkylene group having a carbonyl group, a fullylene group having a halogen atom, an alkylene group having an unsaturated bond, and more preferably an alkylene group and an alkylene group having an ether bond.

The member is benzyl p-benzyloxybenzoate, β
-naphthylbenzyl ether, β-caftoeic acid phenyl ester, l-hydroxy-1-caftoeic acid phenyl ester, β-naphthol (p-chlorobenzyl) ether, β-naphthol (p-methylbenzyl ether,
α-Naphthylbenzyl ether, ea Hiro-butanediol-p-methylphenyl ether, /l Hiro-butanediol-p-isopropylphenyl ether, l.

goubutanediol-pt-octylphenyl ether, cofenoki'/-/-p-tolyloxy-ethane, l-phenoxy-J-(4c-ethylphenoxydineethane, l-phenoxyco(μmchlorophenoxyphethane) , l, 4L-butanediol diphenyl ether (4t, Hiro'-methoxyphenylthio)ethane, benzoic acid phenyl ester, benzoic acid -p-methoxyphenyl ester/', benzoic acid tri-p-chlorophenyl ester, terephthalic dibenzyl ester, benzoic acid (β-p-phenylphenoxyethyl) ester, phenoxy~)acid-1)-chlorophenyl ester, phenoxyacetic acid-p-methylphenyl ester, phenoxyacetic acid-β-tephthyl ester, N-pencylbenzamide, Examples include octadecylbenzamide, hebenzylphenyl acetic acid amide, hephenyl stearic acid amide, and the like.

The pigment to be added to the heat-sensitive coloring layer preferably has a bulk density of 0 ++ 197 cm 3 or less measured by the tapping method in order to make the density of the heat-sensitive coloring layer 0.7 g 7 cm or less. Specific examples include calcium carbonate, calcined kaolin, amorphous silica, gauze, magnesium carbonate, barium carbonate, urea-formalin resin filler, and the like. Pigment usage amount d The density of the thermosensitive coloring layer is 0, 7177c
In order to make it less than m3, it is generally preferable that the amount of zoH is at least the percent of the weight of the heat-sensitive coloring layer, although it varies depending on the bulk density of the pigment.

Examples of the binder used in the heat-sensitive coloring layer include water-soluble polymers and water-insoluble binders exemplified as binders for the undercoat layer.

Higher fatty acid metal salts are used as metal stones, specifically zinc stearate, calcium stearate,
Examples include aluminum stearate.

If necessary, wax, anti-fading agent, surfactant, etc. may be added to the heat-sensitive coloring layer.

(Implementation of the InventionffAJ) Examples are shown below, but the present invention is not limited thereto.

(Preparation method of base paper) Calcined kaolin (Ansiliex 0
(manufactured by Engel-Ruth), the toy was diluted with 0.0% sodium hexametaphosphate. It was dispersed with a homogenizer together with Ji% bath solution tl, 0/l. The coating liquid obtained by adding this dispersion togvc4tr thysterene-butadiene latex (manufactured by Sumitomo Naugatac Co., Ltd.) lrg was
It was coated on high-quality paper using a wire spar so that the dry coating amount was 4117 m2, and dried in a ROOC oven to obtain an undercoat base paper.

(Example 1) Coanilino 3-methyl-he-1'methyl-hecyclohexylaminofluorane was used as a color former, bisphenol A was used as a color developer, and β-naphthylbenzyl ether 209 was used as a sensitizer, each in an amount of 100 g! Tivoli vinyl alcohol (Kuraray PVA-70) was dispersed in a ball mill with a water bath solution overnight to give a volume average particle diameter of 3 μm or less.

As a pigment, amorphous silica (Mizukasil P
-132 Mizusawa chemical force density 0, /Ill/cm
), 20g of hexametaphosphate was dispersed with a homogenizer together with 1&Og of hexametaphosphoric acid Noda O1j% bath solution.

Co-anilino 3
-Methyl-4-N-methylhecyclohexylua is a nofluorane dispersion! y, bisphenol A dispersion/O
j; l, β-naphthylbenzyl ether dispersion iop,
Amorphous silica dispersion liquid/19 was mixed, and further J/
% stearin@starch lead emulsion J g'l"115
A heat-sensitive coating liquid was obtained by boiling at 71°C.

This heat-sensitive coating liquid was coated on the undercoat paper using a wire bar so that the dry coating amount was 7 g/rlL2, and then dried in an oven at 00C to obtain a heat-sensitive recording material.

(Example 2) A thermosensitive recording material was obtained by changing the amount of the amorphous silica dispersion added in Example 1 to 2 kg.

(Example 3) Instead of adding the amorphous 7-liquid dispersion trg of Example 1, 4 tons of calcined kaolin (Ansilex® 3, Engelhardt Co., Ltd., bulk density O1≠/17/cm3) dispersion was added!
IfA was added to obtain a heat-sensitive recording material.

(Comparative Example 1) Instead of adding the amorphous silica dispersion/Ill of Example 1, calcium carbonate (Univer 70. Shiroishi Industries bulk density 0.A197cm) dispersion/rfi was added to prepare a heat-sensitive recording material. Obtained.

(Comparative Example 2) Instead of hot springing the amorphous silica/19 of Example 13'lJ 1, Calcilla carbonate A (Brill 1iant/yo, Shiraishi Kogyo, Casa@g O, j II 97cm) was used.
A heat-sensitive recording material was obtained by adding 19 fractions of liquid.

The color density is a printing test model made by Kyocera and the printing energy is 30m.
The printed color density was measured in J/mm 2 using a Macbeth densitometer.

Tod reproducibility is printing energy 2 after Kyocera printing test
Dots were printed at j mJ/mm, the area of each μO dot was determined using an image analyzer, and the standard deviation of the area divided by the average value was taken as the value of dot reproducibility. The smaller this value is, the better the dot reproducibility is.

The following results are shown in Table 1.

Claims (1)

[Claims] In a heat-sensitive recording material in which an undercoat layer containing a pigment and a binder as main components is provided on a support, and a heat-sensitive coloring layer is provided on the undercoat layer, the density of the heat-sensitive coloring layer is 0.7 g/cm^
A heat-sensitive recording material characterized by having a temperature of 3 or less.