JPH1142860A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording material which hardly picks up tailings to a thermal head and has a recorded image part formed with almost no color which disappears even though coming into contact with a plasticizer. SOLUTION: In the thermal recording material with a thermal development layer which uses a development reaction between leuco dye and a developer, formed on a support, at least, one type of the developer in an antipyrine complex of zinc thiocyanate and contains 1,2-diphenoxy methylbenzene.

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, and more particularly, to a heat-sensitive recording material having excellent color developability, little decoloration of an image due to a plasticizer of a recorded image, and extremely little residue adhesion to a thermal head. .

[0002]

2. Description of the Related Art Recently, diversification and increase of information, resource saving,
Various recording materials have been researched, developed and put to practical use in the information recording field in response to the demands of society such as non-polluting. Among them, thermosensitive recording materials are: (1) Coloring images by simply heating (2) that the recording can be performed using a relatively simple and compact apparatus, that the obtained recording material is easy to handle and that the maintenance cost is low, (3) In many cases, paper is used as the support. In this case, not only the cost of the support is low, but also the output of the computer is advantageous because the obtained recording material has an advantage that the feel of the recording material is close to that of plain paper. It is widely used in the field of printers such as calculators, low- and high-speed facsimile machines, vending machines, thermal copying machines, and POS system labels.

[0003] A recording material is generally a recording material comprising a support having thereon a recording layer mainly composed of an electron-donating colorless or light-colored dye precursor and an electron-accepting developer. By applying each recording energy such as a recording method and a current recording method, the dye precursor and the developer react instantaneously,
A recorded image can be obtained.
And Japanese Patent Publication No. 45-14039. A recording material using such an electron-donating dye precursor and an electron-accepting color developer has excellent properties such as good appearance, good feel, high color density, etc. Is in contact with plastics such as polyvinyl chloride,
It has a drawback that storage stability as a recording material is poor, such as decolorization by a plasticizer or an additive contained in plastic.

[0004] It has been proposed to use an antipyrine complex of zinc thiocyanate as a color developer to improve the storage stability of the recorded image area. However, the antipyrine complex of zinc thiocyanate has the disadvantages of low color-forming sensitivity and high adhesion of thermal head scum. In order to remedy this drawback, Japanese Patent Application Laid-Open No. 4-10982 discloses a method in which a specific sensitizer is used in combination, but the effect is not sufficient, and problems such as coloration of the background in a high-temperature environment are also encountered. There is also.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a high-sensitivity heat-sensitive recording method in which the decoloration of a recorded image area is minimized even when it comes into contact with a chemical such as a plasticizer and the adhesion of scum to a thermal head is extremely small. Is to provide the material.

[0006]

According to the present invention, there is provided a heat-sensitive recording material having a thermosensitive coloring layer provided on a support utilizing a coloring reaction between a leuco dye and a developer. Is a zinc thiocyanate antipyrine complex, and contains 1,2-diphenoxymethylbenzene.

The heat-sensitive coloring layer has an oil absorption of 100 ml.
/ 100 g (JIS K5101, 21) or more, the above thermosensitive recording material is provided.

[0008] Further, there is provided the above-mentioned thermosensitive recording material, wherein an under layer containing a hollow plastic filler is provided between the support and the thermosensitive coloring layer.

The leuco dye used in the thermosensitive coloring layer of the present invention may be used alone or as a mixture of two or more. As such a leuco dye, those used in this type of thermosensitive recording material are optional. For example, leuco compounds of dyes such as triphenylmethane, fluoran, phenothifudine, 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-cyclohexialamino-6-chlorofluoran, 3-dimethylamino-5 7-dimethylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3
-Diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3
-(Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 2- {N (3'-trifluoro) Methylphenyl) amino} -6-diethylaminofluoran, 2- {3,6-bis (diethylamino)-
Lactam 9- (o-chloroanilino) xanthylbenzoate, 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- (N, N -Diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8'-
Methoxy-benzoindolino-pyrrospirane, 6'-
Bromo-3'-methokine-benzoindolino-pyrrospirane, 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-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran, 3-
N-ethyl-N-(-2-ethoxypropyl) amino-
6-methyl-7-anilinofluoran, 3- (N-methyl-N-isobutylamino) -6-methyl-7-anilinofluoran, 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
-Di-n-butylamino-6-methyl-7-anilinofluoran, 3,6-bis (dimethylamino) fluorenespiro (9,3 ')-6-dimethylaminophthalide,
-(N-benzyl-N-cyclohexylamino) -5,
6-benzo-7-α-naphthylamino-4′-bromofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-6-methyl-7
-Mesitidino-4 ', 5'-benzofluoran, 3-N
-Methyl-N-isopropylamino-6-methyl-7-
Anilinofluoran, 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran, 3
-Diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluoran and the like.

In the present invention, an antipyrine complex of zinc thiocyanate is used as a color developer, but it can be used in combination with another color developer. Examples of the developer used in combination with the zinc thiocyanate antipyrine complex include phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof.
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-hydroxy-4'-isopropoxydiphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4, 4'-diphenol sulfoxide, isopropyl P-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, 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'-Diallyl-4,4'-diphenol sulfone, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, tetrabromobisphenol A, tetrabromobisphenol S, 4,4′-thiobis (2 -Methylphenol), 4,4'-thiobis (2-chlorophenol)
etc.

In the present invention, 1,2-diphenoxymethylbenzene is contained in the thermosensitive coloring layer. 1,2-Diphenoxymethylbenzene is contained in an amount of 10 to 200 parts by weight, preferably 20 to 100 parts by weight, based on 100 parts by weight of the antipyrine complex of zinc thiocyanate.

Further, the present invention provides 1,2,3
-Diphenoxymethylbenzene is used, but other heat-fusible substances can be used in combination. Specific examples thereof include the following. Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzyl Biphenyl, terphenyl, triphenylmethane, p-
Benzyl benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1 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, 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 and the like.

In the present invention, it is preferable to contain a pigment in addition to the leuco dye, the antipyrine complex of zinc thiocyanate and 1,2-diphenoxymethylbenzene. In this case, examples of the pigment include inorganic pigments such as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium and silica, and urea-formalin. Organic pigments such as resin, styrene / methacrylic acid copolymer, and polystyrene resin can be exemplified. Above all, the oil absorption is 100ml / 100g (JIS K5
101, 21) It is preferable to contain inorganic pigments as described above. The inorganic pigment having an oil absorption of 100 ml / 100 g or more is desirably contained in an amount of 10 to 200 parts by weight, preferably 100 to 150 parts by weight, per 100 parts by weight of the antipyrine complex of zinc thiocyanate.

In the present invention, if necessary,
Auxiliary additives commonly used in this type of heat-sensitive recording material can be used. For example, in order to prevent sticking with a thermal head, metal soaps such as zinc stearate and aluminum stearate, and various waxes such as polyethylene wax, carnauba wax and paraffin wax can be used. In addition, use surfactants such as special carboxylic acid, acetylene alcohol, dialkyl sodium sulfosuccinate, metal salt of lauryl sulfate, polystyrene ammonium sulfate, special phosphate, etc., antifoaming agents, fluorescent dyes, ultraviolet absorbers, etc. Can be.

In the heat-sensitive recording material of the present invention, various conventional binder resins can be appropriately used for applying the heat-sensitive coloring component and the auxiliary additive component. Specific examples thereof include water-soluble polymers such as polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid. Ester copolymer,
Examples include acrylamide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt of isobutylene / maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, casein and the like. Examples of the aqueous polymer emulsion include latexes such as styrene / butadiene copolymer and styrene / butadiene / acrylic copolymer, vinyl acetate resin, vinyl acetate / acrylic copolymer, and styrene / acrylic acid ester copolymer. Emulsions such as coalescence, acrylate resin, and polyurethane resin are exemplified.

Further, in the heat-sensitive recording material of the present invention, it is preferable to provide an under layer containing a hollow plastic filler between the support and the heat-sensitive color-forming layer for the purpose of improving color-forming sensitivity. As the hollow plastic filler, styrene /
It is preferable to use an acrylic copolymer or polyvinylidene chloride having a hollow ratio of 30 to 90% by volume. As the binder resin for the hollow plastic filler, the above-mentioned water-soluble resin or aqueous polymer emulsion is used.

An over layer can be provided on the heat-sensitive coloring layer, if necessary, for the purpose of improving the matching property with respect to a thermal head or the like, and further improving the storage stability of a recorded image.

The heat-sensitive recording material of the present invention is produced by applying the above-mentioned coating solution for forming each layer on a suitable support such as paper, synthetic paper, plastic film and the like, and drying it. Applied to

[0021]

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

Example 1 (Solution A) 3- (N-dibutyl) amino-6-methyl-7-anilinofluoran 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts (Solution B) zinc thiocyanate Antipyrine complex 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts (Liquid C) 1,2-diphenoxymethylbenzene 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts (D liquid) Silica (Mizukasil P- manufactured by Mizusawa Chemical) 603 oil absorption about 110 ml / 100 g) 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts Mixtures having the above composition, each having an average particle size of 2 μm
Disperse using a sand mill as follows (Solution A),
(Solution B), (Solution C) and (Solution D) were prepared.

(E liquid) Plastic spherical hollow particle dispersion HP-91 (solid content: 27%) 37 parts (manufactured by Rohm and Haas) Styrene / butadiene copolymer latex (solid content: 47%) 4 parts Polyvinyl alcohol 10% Aqueous solution 10 parts Water 49 parts The mixture having the above composition was stirred and mixed to prepare (solution D). This was coated and dried on the surface of a commercially available high-quality paper (basis weight: 52 g / m ² ) so that the dry adhesion amount was 3.5 g / m ² , to obtain an undercoated paper.

(Solution F) (Solution A) 8 parts (Solution B) 24 parts (Solution C) 16 parts (Solution D) 32 parts Dispersion of zinc stearate (solid content 30%) 2 parts Water 18 parts The above composition The resulting mixture was mixed and stirred to prepare a thermosensitive coloring layer coating solution (Solution F). This was coated on the surface of the undercoated paper after drying to a weight of 4.6 g / m ² and dried to form a heat-sensitive coloring layer.
A super calender treatment was performed for 0 to 600 seconds to obtain a heat-sensitive recording material of the present invention.

Example 2 (Solution G) Aluminum hydroxide (Heidilite H-42M manufactured by Showa Denko Approx. 40 ml / 100 g) 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts It was dispersed using a sand mill so as to have a diameter of 2 μm or less to prepare (G solution). A heat-sensitive recording material was produced in the same manner as in Example 1 except that the above (G solution) was used instead of (D solution) in Example 1.

Example 3 A heat-sensitive recording material was produced in the same manner as in Example 1, except that the thermosensitive coloring layer was formed on the support without providing the under layer.

Comparative Example 1 (Solution H) (Solution A) 8 parts (Solution B) 24 parts (Solution D) 32 parts Dispersion of zinc stearate (solid content 30%) 2 parts Water 34 parts Mixture having the above composition Were mixed and stirred to prepare a thermosensitive coloring layer coating solution (H solution). In Example 3, the above (solution H) was used in place of (solution F), and the weight after drying was 3.8 g /
to prepare a heat-sensitive recording material other than having a coloring layer by coating and drying m ² and so as in the same manner as in Example 3.

Comparative Example 2 (Solution I) Di (p-methylbenzyl) oxalate 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts A mixture having the above composition was mixed with a sand mill so that the average particle diameter was 2 μm or less. (Liquid I) was prepared by dispersing the solution.

(Solution J) (Solution A) 8 parts (Solution B) 24 parts (Solution I) 16 parts (Solution D) 32 parts Dispersion of zinc stearate (solid content 30%) 2 parts Water 18 parts The above composition The resulting mixture was mixed and stirred to prepare a thermosensitive coloring layer coating solution (Solution J). A heat-sensitive recording material was produced in the same manner as in Example 3 except that (J liquid) was used instead of (F liquid).

Comparative Example 3 (Solution K) 4-hydroxy-4′-isopropoxydiphenyl sulfone 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts A mixture having the above composition was sand-milled so as to have an average particle diameter of 2 μm or less. (K solution).

A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the above (Liquid K) was used instead of (Liquid B).

Each of the heat-sensitive recording materials prepared as described above was tested for color sensitivity, plasticizer resistance, and adhesion of scum to a thermal head. Table 1 shows the results. The test was performed as follows.

Color sensitivity: using a thermal printing test apparatus having a thin film head manufactured by Ricoh Co., Ltd., a head power of 0.45 W /
dot, a pulse period of 4 msec / line, a main scanning line density of 8 dots / mm, and a sub-scanning line density of 7.7 dots / mm, printing was performed with a pulse width of 0.5, 0.7, and 0.9 msec. The density was measured with a Macbeth densitometer RD-914.

Plasticizer resistance test: Three sheets of a vinyl chloride wrap film (manufactured by Shin-Etsu Polymer Co., Ltd.) were superimposed on the 0.9 ms printed image, and a load of 50 gf / cm ² was applied.
After storing for 5 hours, the density of the image area is measured by Macbeth densitometer RD-
914.

Dust adhesion test on thermal head: TE
After performing black solid printing with a length of 10 cm five times with a C label printer, the thermal head was observed and judged.

[0036]

[0037]

[Table 1]

From Table 1, it can be seen that the heat-sensitive recording material of the present invention is excellent in color sensitivity and plasticizer resistance and has very little residue attached to the thermal head.

[0039]

As described above, in the heat-sensitive recording material of the present invention, the recorded image area formed by the heat-sensitive recording material is hardly decolored even when a chemical such as a plasticizer comes into contact, and adheres to the thermal head. Is also very small.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomoyuki Kugo 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (3)

[Claims] An antipyrine complex of zinc thiocyanate in a thermosensitive recording material having a thermosensitive coloring layer provided on a support utilizing a coloring reaction between a leuco dye and a developing agent. And a thermal recording material containing 1,2-diphenoxymethylbenzene. 2. The thermosensitive coloring layer has an oil absorption of 100 ml / 1.
2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording material contains at least 00 g (JIS K5101, 21) of an inorganic pigment. 3. A heat-sensitive recording material according to claim 2, wherein an under layer containing a hollow plastic filler is provided between said support and said heat-sensitive coloring layer.