JPS60174685A - Thermal recording material - Google Patents

Abstract

PURPOSE:To contrive to enhance head matching property, by a method wherein a thermal color forming layer comprising a leuco dye and a color developer is provided on a base, and an overcoat layer comprising a metallic salt of higher fatty acid having a specified melting point is provided thereon. CONSTITUTION:An overcoat layer comprising a metallic salt of higher fatty acid having a melting point of not lower than 200 deg.C is used. The metallic salt may be lithium stearated, which is known as a metallic soap or the like, and the amount of the salt is 0.1-5 times by weight of the amount of the dye. A binder is used in an amount of 0.01-0.5pts.wt. as against 1pts.wt. of the metallic salt. A leuco compound of a dye based on triphenylmethane or the like is used as the leuco dye. A phenolic substance or the like is used as the color developer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer.

[Prior art]

A thermosensitive recording material is a recording material having a structure in which a so-called thermosensitive coloring layer that develops color when heated is formed on a support such as paper, synthetic paper, or resin film, and a thermal head is used for heating to develop the color. A built-in thermal printer is used. Compared to other recording materials, such recording materials can produce records in a short time using relatively simple equipment without complex processes such as development and fixing, and are less likely to generate noise or pollute the environment. Due to its advantages such as the absence of paper and low cost, it is used not only for copying books and documents, but also as a recording material in a wide range of applications such as electronic computers, facsimile machines, ticket vending machines, labels, and recorders. Thermochromic compositions used in such heat-sensitive recording materials generally consist of a color former and a color developer that causes the color former to develop color when heated. As the color former, for example, a composition having a lactone, lactam or spiropyran ring Colorless or light-colored leuco dyes are used, and various acidic substances such as organic acids and phenolic substances are used as color developers. A recording material that combines a color former and a color developer has the advantage that the resulting image has a particularly clear color tone, a white background, and the image (dye image) has excellent weather resistance. , is widely used.

Such a heat-sensitive recording material has a thermal head, as described above,
Color is developed when heated by contact with a hot pen, etc., but in order to obtain a colored image with high density, it is necessary to heat-melt each component in the heat-sensitive coloring layer sufficiently to cause a sufficient coloring reaction. However, in this case, there are problems such as components in the thermosensitive coloring layer adhering to the thermal head (residue adhesion), which impedes the running performance of the thermal head, and causes trailing and white spots (partial falling off of the colored image). is likely to occur. The property of a heat-sensitive recording material related to the contact between the heat-sensitive coloring layer and the thermal head, etc. is called head matching property, and is extremely important when considering the quality of the heat-sensitive recording material. .

Various proposals have been made in the past to improve head matching properties, but these have not been fully satisfactory in practice, as the effect of improving head matching properties has not been sufficient.

〔the purpose〕

An object of the present invention is to overcome the problems of the prior art and provide a heat-sensitive recording material with improved head matching properties.

〔composition〕

According to the present invention, in a support provided with a heat-sensitive coloring layer containing a leuco dye and a color developer, an overcoat layer containing a higher fatty acid metal salt having a melting point of 200° C. or higher is provided on the heat-sensitive coloring layer. Provided is a heat-sensitive recording material characterized in that it is provided with.

In the present invention, the overcoat layer has a melting point of 200
It is characterized by using an overcoat layer containing a higher fatty acid metal salt at a temperature of ℃ or higher, usually 200 to 300℃,
In this case, as the higher fatty acid metal salt, those conventionally known as metal soaps are used, and examples thereof include lithium stearate, barium stearate, and sodium stearate. What is the proportion of higher fatty acid metal salts used?

0.1 to 5 times the weight of the leuco dye, especially 0.2
It is preferable to use it in an amount of ~0.5 times by weight. It is known to use a layer containing an ax-like substance such as stearic acid amide as an overcoat layer, but in this case, sufficient head matching properties are not yet obtained and problems such as tailing and head residue adhesion occur. It also has poor image clarity.

Further, among higher fatty acid metal salts, those having a melting point lower than 200 DEG C., such as magnesium stearate, do not have the effect of improving head matching properties.

The overcoat layer can be formed by coating and drying the higher fatty acid metal salt together with a binder on the heat-sensitive coloring layer. In this case, the binder is used in an amount of 0.01 to 1 part by weight per 1 part by weight of the higher fatty acid metal salt. 0.5 part by weight, preferably 0.04
It is preferable to use it in a proportion of ~0.1 part by weight. Further, as the binder, various kinds of binders shown below in relation to the heat-sensitive coloring layer can be used.

The leuco dyes used in the present invention can be applied singly or in combination of two or more types, but such leuco dyes include:
Any dye that has been applied to this type of heat-sensitive material may be used. For example, leuco compounds of dyes such as triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran dyes are preferably used. Specific examples of such leuco dyes include those shown below.

3.3-bis(P-dimethylaminophenyl)-phthal=
4-lido, 3.3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(P-dimethylaminophenyl)-6-dibutylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7 -dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-hly-N-ethylamino)-6-methyl-7-anilitous fluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2 - (N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid 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-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-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'- 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy- 5'-nitrophenyl) phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy5'-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)fluoran , 3-(N-ethyl-P-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(0-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7- (α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluoran, 3-(N-benzyl-cyclohexylamino)-5゜6
-penzo7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidi8-no4',5'-benzofluorane, and the like.

Further, as the color developer used in the present invention, various electron-accepting substances that react with the leuco dye and develop color when heated are used, and specific examples thereof include phenol as shown below. Examples include acidic substances, organic or inorganic acidic substances, and salts thereof.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-Cyclohexylsalicylic acid, 3,5-ter
t-Butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene bis (2,6-
dibromophenol), 4,4'-isopropylidene bis(2,6-dichlorophenol), 4゜4'-isopropylidene bis(2-methylphenol), 4,4'-
Isopropylidene bis(2,6-dimethimephenol)
, 4,4'-isopropylidene bis(2-tert-butylphenol), 4,4'-5ee-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2- methylphenol), 4-tert-butylphenol, 4
-Phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolac type phenolic resin, 2,2'-thiobis( 4,6-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycin, phloroglycin carboxylic acid, 4-t, ert-octylcatechol, 2,2'-
Methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2゜2'-dihydroxydiphenyl, ethyl P-hydroxybenzoate, propyl P-hydroxybenzoate, P- Butyl hydroxybenzoate, benzyl P-hydroxybenzoate, P-chlorobenzyl P-hydroxybenzoate, 0-chlorobenzyl p-hydroxybenzoate, ρ-methylbenzyl P-hydroxybenzoate, P
-n-octyl hydroxybenzoate, benzoic acid, zinc salicylate, -hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenylsulfone, 4-
Hydroxy-4'-chlorodiphenylsulfone, bis(
4-hydroxyphenyl) sulfide, 2-hydroxy-p-1-ruylic acid, zinc 3,5-di-tert-butylsalicylate, tin 3゜5-di-tert-butylsalicylate, tartaric acid, oxalic acid, maleic acid, citric acid , succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, etc.

In the present invention, in order to bind and support the leuco dye and color developer on the support, various commonly used binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxycellulose, hydroxyl, etc. Cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acryl amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid = 11
- In addition to water-soluble polymers such as ternary copolymers, styrene/maleic anhydride copolymer alkali salts, isobutylene/maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, polyacetic acid vinyl,
Polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate-1-, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer A latex such as a polymer can be used.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible substances ( or lubricant), 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. , urea--1
,2-,,,) Examples include organic fine powders such as formalin rosin, styrene/methacrylic acid copolymer, and polystyrene resin; examples of thermofusible substances include higher fatty acids or their esters, and amides. Alternatively, in addition to metal salts, various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermoplastics. Examples include those having a melting point of about 50 to 200°C, such as meltable organic compounds.

〔effect〕

The heat-sensitive recording material of the present invention has the above-mentioned structure, and has significantly improved head matching properties.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 A mixture having the following composition was prepared in a ball mill.
The mixture was mixed and dispersed for 4 hours to prepare solutions A, B, G, D, E, F, and G.

(Liquid A) 3-dimethylamino-6-methyl-7-N-phenylaminofluorane 10 parts 10% hydroxyethylcellulose aqueous solution 10n water
3011 (Liquid B) Bisphenol A 15 parts 10% hydroxyethylcellulose aqueous solution 3.5n Water 20 parts (G liquid) Calcium carbonate 15 parts 5% methylcellulose aqueous solution 15u Water 2oI! (Liquid D) Lithium stearate (mp = 220°C) 10 parts 5
% methimecellulose aqueous solution 10II polyoxyethylene nonylphenol ether (surfactant) 0.1/! Water 29.9 parts (Liquid E) Barium stearate (mp = 225°C) 10 parts 5% methylcellulose aqueous solution I Q n Polyoxyethylene nonylphenol ether 0,1 // Water 2 (1,911 (Liquid F) Stearic acid Amide (mp = 1oooC) 10 parts 5%
Methimecellulose aqueous solution I Q lZ water 3oI! Next, 10 parts of the above liquid A, 30 parts of liquid B, 15 parts of liquid C, and 1
A heat-sensitive coloring layer coating solution was prepared by mixing 20 parts of a 0% polyvinyl alcohol aqueous solution. Further, coating solutions (1) to (4) for overcoat shoes were prepared using the above-described solutions to G.

(1) Liquid 1 part 10% polyvinyl alcohol aqueous solution 201! (2) Solution 15 - Solution E 1 part 10% polyvinyl alcohol aqueous solution 20 parts (3) Solution F 1 part 10% polyvinyl alcohol aqueous solution 20 parts (4) Solution G 1 part 10% polyvinyl alcohol aqueous solution 20 parts Next, After applying the above-mentioned heat-sensitive coloring layer coating solution to commercially available high-quality paper with a standard basis weight of 60 g/ITf using a selected wire bar so that the dry adhesion amount is 6 g/rri' to form a heat-sensitive coloring layer,
On top of that, apply the overcoat layer coating solution with a dry weight of 4g.
/rd and dried to obtain a heat-sensitive recording material.

The heat-sensitive recording material obtained above was surface-treated using a super calender, and then processed using a G-nT mode simulator with a built-in thermal head at a head voltage of 14°V and a pulse width of 1.5 m.
When printing with s, there may be residue adhesion to the thermal head, tailing,
Whitening and image clarity (image blurring) were evaluated. The results are shown in Table 1.

The evaluation criteria shown in Table 1 are as follows.

0...Very good 0...Good Δ...Slightly poor X...Poor Table-1 1 Comparative example is shown.

As can be seen from the results shown in Table 1, the product of the present invention has excellent head matching properties, does not have head debris attached,
In addition, clear images were obtained without trailing, white spots, or blurring, whereas the comparative product had head residue adhesion and blurring of the image, which caused problems in practicality.

Claims (1)

[Claims] (1) A thermosensitive coloring layer containing a leuco dye and a color developer is provided on a support, and a melting point of 200
A heat-sensitive recording material comprising an overcoat layer containing a higher fatty acid metal salt having a temperature of ℃ or higher.