JPH08118808A - Thermal recording material - Google Patents

Abstract

PURPOSE: To enhance barrier properties to chemicals or the like by a method wherein in a thermal recording material formed by providing a thermally color- forming layer producing a color under heat on a substrate and a protective layer mainly composed of a water-soluble resin on the thermally color-forming layer, the thermally color-forming layer has a specific surface contact angle. CONSTITUTION: In a thermal recording material provided with a thermally color-forming layer mainly composed of a thermally color-forming composition on a substrate of paper, synthetic paper, a plastic film, or the like and heated by a thermal head, a thermal pen, laser light, or the like to form a color image, an under coat layer, the thermally color-forming layer, and a protective layer are provided in order on the substrate. The thermally color-forming layer is so formed as to have a surface contact angle of 70 deg.C or lower. In this manner, the protective layer can be ideally uniformly applied to the surface of the thermally color-forming layer without cissing and a pinhole. As an example of forming the thermally color-forming layer of a surface contact angle of 70 degrees or less, a surfactant, a filler, a color former of a small surface contact angle, or the like is incorporated in the thermal recording layer.

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 an excellent barrier property against chemicals.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally comprises a support such as paper, synthetic paper, plastic film and the like, provided with a heat-sensitive color-forming layer containing a heat-colorable composition as a main component.
A colored image can be obtained by heating with a laser beam or a strobe lamp. Compared to other recording materials, this type of recording material can be recorded in a short time with relatively simple equipment without performing complicated processing such as development and fixing, and it generates less noise and less environmental pollution. Due to its advantages such as low cost, it is widely used as a recording material in various fields such as electronic calculators, facsimile machines, ticket vending machines, labels, recorders, etc., in addition to being used for copying books and documents.

The thermochromic composition used for such a heat-sensitive recording material comprises a general color former and a color developer which allows the color former to develop color when heated, and examples of the color former include lactone, lactam or spiropyran ring. A colorless or light-colored leuco dye having ## STR3 ## and an organic acid or a phenolic substance has been conventionally used as a developer. The recording material obtained by combining the color-developing agent and the color-developing agent has the advantages that the color tone of the obtained image is particularly clear, the background whiteness is high, and the weather resistance of the image is excellent. Widely used.

However, this type of heat-sensitive recording material is
When it comes into contact with a plasticizer such as OP or oils and fats, it has a defect that the image is erased and the background portion is colored.
In order to overcome these drawbacks, a protective layer has been conventionally provided on the thermosensitive coloring layer, and the components constituting this protective layer include a water-soluble resin such as polyvinyl alcohol or starch and a glyoxal or an epoxy compound. Fillers such as calcium carbonate and silica and wax have been used as cross-linking agents such as as a matching improvement aid. Also,
To further improve the oil resistance, for example, JP-A-59-4
As described in Japanese Patent Nos. 5191 and 59-67081, it has been proposed to laminate two protective layers.

[0005]

However, a certain degree of oil resistance and plasticizer resistance can be achieved by installing a protective layer having a constitution in which a water-soluble resin and a cross-linking agent as described above are added with a matching aid. However, it has not been sufficiently satisfied in practical use, and the oil resistance and the like can be improved by providing a two-layer laminated protective layer, but the coloring sensitivity is inferior. Therefore, an object of the present invention is to provide a heat-sensitive recording material which overcomes the above-mentioned problems, that is, has excellent barrier properties such as oil resistance and plasticizer resistance.

[0006]

According to the present invention, in a thermosensitive recording material comprising an underlayer, a thermosensitive coloring layer and a protective layer provided on a support in this order, the surface contact angle of the thermosensitive coloring layer is 7
There is provided a heat-sensitive recording material characterized by being 0 ° or less.

That is, in the heat-sensitive recording material of the present invention, the surface contact angle of the heat-sensitive color forming layer is 70 ° or less, preferably 65 °, so that the coating uniformity of the protective layer on the heat-sensitive color forming layer is cissing or pinhole. There will be no good.

The reason for this is not clear at this point in time, but the surface contact angle of the heat-sensitive color forming layer is set to 70 ° or less so that the heat-sensitive color forming layer is applied and then dried in a short time. This is probably because the uniformity of the protective layer is increased because it is easy to spread upward. Examples of the method for setting the surface contact angle of the thermosensitive color developing layer to 70 ° or less include a method in which the thermosensitive recording layer contains a surfactant, a filler, a color former having a small surface contact angle, or the like.

Specifically, an acetylene glycol nonionic surfactant or an organic carboxylic acid salt such as sodium sulfosuccinate, sodium polyacrylate, ammonium polyacrylate, for example, an interface having a wetting effect of sodium salt or ammonium. Activator is the dye 1 in the thermosensitive recording layer
0.05 to 1 part by weight based on 1 part by weight, or 5 to 20 parts by weight of an oil-absorbing filler such as calcium carbonate, silicon dioxide or aluminum hydroxide is added to 1 part by weight of the dye in the heat-sensitive recording layer. A method etc. are illustrated.

The leuco dyes used in the thermosensitive coloring layer of the present invention may be used alone or in admixture of two or more. As such leuco dyes, those applied to this type of heat-sensitive recording material are arbitrarily applied, for example, triphenylmethane-based, fluorane-based, phenothiazine-based, auramine-based, spiropyran-based, indolinophtalide-based, etc. The leuco compound of the above dye is 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
-Chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-N-methyl-N-isobutyl-
6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-
Diethylamino-7-methylflorane, 3-diethylfumino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (N-ethyl-Np-tolyl) -6- Methyl-7-anilinofluorane, 3- (Np-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) xanthylbenzoate lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane,
3-di-ethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 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-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane, 3- (N, N-diethylamino) -5-methyl-7
-(N, N-dibenzylamino) fluorane, benzoyl leuco methylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrolispirane, 6'-bromo-3'-methoxy-benzoindolino-pyrrillospirane, 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) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7 (N-benzyl-tri) Fluoromethylanilino) 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) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino)
Fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methyltoluidino)-
7- (pn-butylanilino) fluorane, 3- (N
-Methyl-N-isopropylamino) -6-methyl-7
-Anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorenspyrro (9,3 ')-6'-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4′-bromofluorane, 3-diethylamino-
6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-
7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4,5-benzofluorane , 3-diethylamino-6-dimethylaminofluorene-9-spiro-3 '
-(6'-Dimethylamino) phthalide, 3,6-bis (diethylamino) fluorene-9-spiro-3'-
(6′-Dimethylamino) phthalide, 3-dibutylamino-6-dimethylaminofluorene-9-spiro-3 ′
-(6'-Dimethylamino) phthalide, 3-diethylamino-6-dimethylaminofluorene-9-spiro-
3 '-(6'-diethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-
Methoxyphenyl) ethenyl} -4,5,6,7-tetrachlorophthalide, 3- (4'-diethylamino-2 '
-Methoxyphenyl) -3- {4 ''-(p-diethylaminophenyl) -4 ''-(p-chlorophenyl)-
1 ″ -3 ″ -butadienyl} -benzo {α} phthalide and the like.

As the color developer used in the thermosensitive color developing layer of the present invention, various electron-accepting compounds which develop the above leuco dye upon contact, such as phenolic compounds, thiophenolic compounds, thiourea derivatives and organic compounds. Acids and metal salts thereof are preferably applied, and specific examples thereof include those shown below. 4,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis (o-methylphenol), 4,4'-secondary-
Butylidene bisphenol, 4,4'-Isopropylidene bis (2-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'-
Butylidene bis (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'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4-hydroxydiphenyl sulfone, 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, hydroxynaphthoic acid Zinc, aluminum,
Metal salts such as 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, 3,4-dihydroxy-4'-methyldiphenyl sulfone, 3,3'-diallyl-4,4'-diphenol sulfone, α, α -Bis (4-hydroxyphenyl)-
α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, etc.

In order to produce the heat-sensitive recording material of the present invention,
When the leuco dye and the color developer are bound and supported on the support, various commonly used binders can be appropriately used, and specific examples thereof include the following. Polyvinyl alcohol, starch and its derivatives, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose,
Cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / Maleic anhydride copolymer alkali salt, polyacrylamide,
In addition to water-soluble polymers such as sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, polyacrylic acid ester, polymethacrylic acid ester, vinyl chloride /
Emulsion of vinyl acetate copolymer, ethylene / vinyl acetate copolymer, etc., latex of styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, etc.

Examples of the filler used in the thermosensitive coloring layer and protective layer of the present invention include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc and surface treatment. Inorganic fine powders such as calcium and silica, as well as organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be mentioned.

The surfactant contained in the heat-sensitive color developing layer can be appropriately selected from anionic or nonionic surfactants. Preferred surfactants include sodium alkylbenzene sulfonate, sodium alkylsulfate, dioctyl sodium sulfosuccinate, polyalkylene glycol (eg, polyoxyethylene nonylphenyl ether), and the like.

In the protective layer of the present invention, a cross-linking agent may be used in combination with the above resins, if desired. For example, glyoxal and its derivatives, epoxy-based cross-linking agent,
Aziridine crosslinking agents, amine crosslinking agents, aldehyde crosslinking agents such as aldehyde starch and glutaraldehyde, melamine crosslinking agents, methylol crosslinking agents, isocyanate crosslinking agents, zirconium metal crosslinking agents, boric acid, polyamide epichlorohydrin crosslinking Agents and the like. Among these, aziridine crosslinking agents, glyoxal and their derivatives are particularly preferable.

In the present invention, an undercoat layer may be provided between the support and the thermosensitive color developing layer, if necessary. In this case, as the components constituting the undercoat layer, the above-mentioned filler, binder, heat-fusible substance,
A surfactant or the like can be used. Further, in the present invention, the protective layer may be composed of two or more layers, or a back coat layer may be provided.

[0017]

EXAMPLES The present invention will now be described in more detail with reference to Examples. All parts and% shown below are based on weight.

Example 1 A mixture having the following composition was pulverized and dispersed in a sand grinder for 2 to 4 hours (solution A), solution B, solution C, solution D, solution E. ) Was prepared. (Solution A) 3-N-cyclohexyl-N-methylamino-6-20 parts Methyl-7-anilinofluorane 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts (Solution B) 4-hydroxyphenyl-4'- Isopropoxy 20 parts Phenylsulfone 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts (solution C) Calcium carbonate 20 parts Water 80 parts (solution D) Silicon dioxide 20 parts Water 80 parts (solution E) Aluminum hydroxide 20 parts Water 80 Parts Further, (A solution): (B solution) was mixed and stirred in a weight ratio of 1: 3, and Surfinol TG (Nisshin Kako) was added to 0.02 parts per 1 part of (A solution). A thermosensitive color developing layer coating liquid was added to prepare a dye, and the amount of the dye applied to commercially available high-quality paper after drying was 0.
It was coated and dried with a wire bar so as to have a weight of 6 g / m ² to obtain a paper coated with a thermosensitive coloring layer. Then, 1 part in 10 parts of (solution E)
20 parts of 0% polyvinyl alcohol aqueous solution and 2 parts of polyamide cross-linking agent are mixed and stirred to prepare a coating solution for the protective layer, and the coated amount on the paper coated with the thermosensitive coloring layer is 2 g / m ² when dried using a wire bar. After coating and drying as described above, a calendering treatment was performed to adjust the surface smoothness to about 600 seconds to obtain a heat-sensitive recording material of the present invention.

[Example-2] A thermosensitive recording material was used in the same manner as in Example-1 except that Demor EP (Kao Atlas Co., Ltd.) was used in place of Surfynol TG (Nissin Kako) of Example-1. Got

[Example-3] (Solution A): (Solution B): (C)
The liquid) was mixed and stirred so that the weight ratio was 1: 3: 10, and the amount of the dye applied to commercially available high-quality paper after drying the dye was 0.6 g / m 2.
^A heat-sensitive recording material was obtained in the same manner as in Example-1, except that the heat-sensitive color developing layer-coated paper was obtained by coating and drying with a wire bar so that the thickness became ² .

[Example-4] A thermosensitive recording material was obtained in the same manner as in Example-3, except that (D-solution) was used instead of (C-solution) in Example-3.

[Example-5] (Solution A): (Solution B): (C)
A heat-sensitive recording material was obtained in the same manner as in Example-3, except that the liquid) was mixed and stirred so that the weight ratio became 1: 3: 5.

[Example-6] A thermosensitive recording material was obtained in the same manner as in Example-5 except that (D liquid) was used in place of (C liquid) in Example-5.

[Comparative Example-1] A thermosensitive recording material was obtained in the same manner as in Example-1, except that Surfynol TG (Nisshin Kako) of Example-1 was omitted.

Comparative Example-2 Demol EP of Example-2
A thermosensitive recording material was obtained in the same manner as in Example-2 except that (Kao Atlas Co., Ltd.) was omitted.

[Comparative Example 3] A thermosensitive recording material was obtained in the same manner as in Example 3 except that the liquid C in Example 3 was omitted.

The thermal recording material obtained above was tested for contact angle, oil resistance and plasticizer resistance by the following methods. The results are shown in Table 1. [Preparation and measurement of test sample] A sample was prepared by printing using a thermal inclinometer (manufactured by Toyo Seiki Seisakusho) with a built-in thermal head under the conditions of a temperature of 150 ° C., a crimping time of 1 second and a crimping pressure of 2 kg / cm ² . The density value is the measurement result by Macbeth densitometer R-914 type, and the filter is the measurement result by W-106. [Plasticizer resistance test] A polyvinyl chloride sheet containing a plasticizer was superposed on the colored portion printed at 150 ° C.
A load of g / cm ² is applied, and the image density after storage for 15 hours at 40 ° C. is measured. [Oil resistance test] A colored portion printed at 150 ° C is coated with cottonseed oil, and the image density after storage for 15 hours at 40 ° C is measured. [Contact Angle] Water is added to the paper coated with the thermosensitive coloring layer using an automatic contact angle meter (Kyowa Interface Science Co., Ltd.), and the contact angle on the surface of the thermosensitive coloring layer is measured.

[0028]

[Table 1] From Table 1, it can be seen that the heat-sensitive recording material of the present invention is superior in oil resistance and plasticizer resistance to the heat-sensitive recording material of Comparative Example.

[0029]

As described above, the heat-sensitive recording material of the present invention has the surface contact angle of the heat-sensitive color forming layer of 70 ° or less, so that the coating uniformity of the protective layer is improved and the barrier against oil and plasticizer is improved. It has excellent properties and is extremely highly practical with little image erasing or bleeding due to them.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising a thermosensitive coloring layer which is colored by heat on a support, and a protective layer containing a water-soluble resin as a main component on the thermosensitive coloring layer. A thermal recording material having an angle of 70 ° or less.