JPS62167084A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance water resistance and chemical resistance, by using not only a N-vinyl imidazole complex of a zinc compound represented by a specific formula as a coupler but also a phenolic compound represented by a specific formula as an auxiliary agent. CONSTITUTION:A N-vinyl imidazole complex of a zinc compound represented by general formula (I) (wherein X is a halogen atom or an acidic residue) is used as a color developer and [1,1,3-tris(2'-methyl-4'-hydroxy-5'-t-butylphenyl) butane] represented by structural formula (II) is used as an auxiliary agent. The proper use amount of the auxiliary agent is 1pts. or less, pref., 0.1-0.5pts. wt of 1pts. of the developer (the N-vinyl imidazole complex of the zinc compound). If said use amount exceeds 1pts. wt., it is not pref. because the stability of a background part is deteriorated. The auxiliary agent is added to the same layer as a leuco dye and the developer or may be added to a layer different from said layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to the improvement of heat-sensitive recording materials containing leuco dyes as color formers, and more particularly to the improvement of water resistance.

[Prior art]

Thermosensitive recording materials generally have a thermosensitive coloring layer containing a thermochromic composition as a main component on a support such as synthetic paper or plastic film.
A colored image can be obtained by heating with a strobe lamp or the like. Compared to other recording materials, this type of recording material
Due to its advantages, such as being able to obtain records in a short time with a relatively simple device without the need for troublesome processes such as fixing, generating less noise and polluting the environment, and being inexpensive,
In addition to being used for copying books, documents, etc., it is also widely used as a recording material in a wide variety of applications, including electronic computers, facsimile machines, ticket vending machines, labels, and recorders. Thermochromic compositions used in such heat-sensitive recording materials generally consist of a coloring agent and a color developer that causes the coloring agent to develop color when heated.
As the coloring agent, for example, a colorless or light-colored leuco dye having a lactone, lactam or spiropyran ring has been used, and as the color developer, an organic acid or a phenolic substance has conventionally been used. A recording material containing a combination of a color forming agent and a color developing agent has the advantage that the resulting image has a clear color tone, has a high background whiteness, and has excellent weather resistance of the image. , is widely used.

Conventionally, bisphenol A and ρ-bitroxybenzoic acid esters have been used as color developers for leuco dyes, but these phenols have high color density but lack the stability of colored images, so they cannot be left alone. Another problem is that the concentration decreases when it comes into contact with fingerprints or other oils and fats. These phenomena occur not only when using phenols but also when general organic acids are used, and there is a strong desire to overcome them. In the field of pressure-sensitive paper, it has been proposed to use a metal compound of aromatic carboxylic acid as a color developer that provides a stable image, as seen in Japanese Patent Publication No. 52-1327. When applied to thermal paper, although the image is stabilized, the non-image area (background area) develops color due to contact with oils and fats, making it difficult to read the image, which makes it difficult to actually apply it to thermal paper. The current situation is difficult. In addition, aromatic oxycarboxylic acids (e.g., salicylic acid, 2-oxy-3
It has also been proposed to use a metal salt (such as naphthoic acid) as a color developer, but this also has the drawback that non-image areas develop strong color upon contact with oils and fats, resulting in a decrease in contrast.

It has also been proposed to use an N-vinylimidazole complex of zinc halide as a color developer, but this product has excellent oil resistance and plasticizer resistance for images, and also produces almost no background color. However, the image quality against water is poor and the density decreases significantly when immersed in water, which is a practical problem.

〔the purpose〕

An object of the present invention is to overcome the problems of the prior art, that is, to provide a heat-sensitive recording material that has excellent water resistance and chemical resistance.

〔composition〕

According to the present invention, in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, an N-vinylimidazole complex of zinc halide represented by the following general formula (1) is used as the color developer. It is characterized by using a phenolic compound represented by the following general formula (II) as an auxiliary agent (wherein, X represents a halogen atom).

) In the present invention, 111 N-vinylimidazole zinc halide of the general formula (1) is used as a color developer.
As an auxiliary agent, (1,1
．． 3-1-Lis(2'-methyl-4'-hydroxy-
5'-t,-butylphenyl)butane], it is possible to obtain an image that is free from background fog and has improved water resistance. The auxiliary agent of general formula (n) used in the present invention is desirably used within a range where the quality of the auxiliary agent is not superior. For example, the color developer represented by the general formula (I) (N-vinylimidazole complex of zinc halide) 1
1 part by weight or less, preferably 0.1 to 0.5 parts by weight
Parts by weight are appropriate. If the amount used exceeds 1 part by weight, the stability of the skin portion deteriorates, which is not preferable. Further, the auxiliary agent of general formula (II) used in the present invention may be added to the same layer as the leuco dye and the color developer, or may be added to the same layer as the leuco dye and the color developer, or may be added in a layer separate from these layers. It may be added to different layers. In either case, an image with improved water resistance can be obtained.

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 is applicable to this type of heat-sensitive material may be used. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. It will be done.

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-diethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorphthalide, 3.3-bis(P-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorfur orane, 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-tolyl-N-ditylamino)-6-methyl-7-anilinofluorane, 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- Chloranilino) fluorane.

3-dibutylamino-7-(Q-chloroanilinofluorane.

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-(:su,N-diethylamino)-5 -methyl-7-
(N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxybe:nozoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane.

3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-me1-xy5'-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)fluoran.

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-ρ-toluidino)-7-(α-phenylethylamino)fluoran, 3- Diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluoran, 3-(N-benzyl-N-siglohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
', 5'-benzofluorane.

In the present invention, in order to bind and support the leuco dye, color developer, and auxiliary agent on the support, various commonly used binders can be used as appropriate, and specific examples thereof include the following: can be mentioned.

Polyvinyl alcohol, starch and its derivatives, methane
-Cellulose derivatives such as xycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolone, acrylamide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid 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, polyvinyl acetate, Polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, auxiliary additive components 1 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-formalin resin, styrene/methacrylic acid copolymer, polystyrene resin, etc. Examples of the thermofusible substance include organic fine powder.

In addition to higher fatty acids or their esters, amides, or metal salts, various waxes, condensates of aromatic carboxylic acids and amines, Anbu, aromatic acid phenyl esters, higher linear glycols, 3,4-epoxy-hexahydro 50 such as dialkyl phthalates, higher ketones, and other thermofusible organic compounds.
Examples include those having a melting point of about ~200°C.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating liquid for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying it. applied to the field of recording.

The heat-sensitive recording material of the present invention is used in various fields, but in particular, it takes advantage of the above-mentioned excellent color image stability,
It can be used for interest as heat-sensitive recording label sheets and heat-sensitive recording magnetic ticket paper. In the case of a heat-sensitive recording type label sheet, a heat-sensitive coloring layer containing the above-mentioned fluoran compound and phenolic compound is provided on one side of the support,
A release mount may be provided on the other side of the support via an adhesive layer, and in the case of magnetic ticket paper, instead of this release mount,
A magnetic recording layer containing a ferromagnetic material and a binder as main components may be provided.

〔effect〕

According to the present invention, in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, an N-vinylimidazole complex of zinc halide represented by the general formula (1) is used as the color developer. By using the compound of general formula (II) as an auxiliary agent, the image has excellent storage stability, oil resistance, and plasticizer resistance, and has almost no coloration on the background, and is water resistant. It is possible to provide a heat-sensitive recording material that provides excellent images.

〔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.

[Liquid A]

3-(N-methyl-3-N-cyclohexyl)amino-
6-Methyl-7-anilite fluorane 20 parts 10
% polyvinyl alcohol aqueous solution 20! I water

60″ Calcium carbonate 10!
! 10% polyvinyl alcohol aqueous solution 251!
water
45n [Liquid C] 1.1.3-tris(2'-methyl-4'-hydroxy-5'-j-butylphenyl)butane 2
0 parts lO% polyvinyl alcohol aqueous solution 201
/water
60I/[Liquid D] Stearylamide 25 parts 10%
Polyvinyl alcohol aqueous solution 251! water

50 nol [Liquid E] Bisphenol A 20 parts Calcium carbonate 1Qn10% polyvinyl alcohol 25/I water
45u
Each of the mixtures having the above compositions was ground and dispersed using a sand grinder for 2 hours to prepare solutions A to E.

Example 1 Fine powder dispersion of styrene/methacrylic acid copolymer (40
%) and 1 part of a 10% polyvinyl alcohol aqueous solution were mixed. The undercoat coating liquid was applied and dried on high-quality paper with a basis weight of 45 g/m so that the dry adhesion amount was 4.5 g/m. Next, the weight ratio of A liquid: D liquid: C liquid: D liquid was 1:
A heat-sensitive coating solution was prepared by mixing and stirring so that the ratio was 3:1:1, and a dry amount of 5.1 g was coated on the undercoat layer.
/rn' and dried, followed by calender treatment to obtain a heat-sensitive recording material of the present invention.

Example 2 Fine powder dispersion of styrene/methacrylic acid copolymer (40
%), 4.5 parts of liquid C, and 1 part of a 10% polyvinyl alcohol aqueous solution was mixed with an undercoat coating liquid having a basis weight of 4.
It was coated and dried on 5 g/m high-quality paper so that the dry adhesion amount was 5.5 g/m.

Next, a heat-sensitive coating liquid was prepared by mixing and stirring liquid A: liquid D: liquid so that the weight ratio was 1:3:1, and the dry coating amount was 4.5 g/rri on the undercoat layer. The mixture was coated and dried, and then calendered to obtain the heat-sensitive recording material of the present invention.

Comparative Example 1 The heat-sensitive coating liquid used in Example 2 was applied and dried on the Underto 1 layer of Example 1 in the same manner as in Example, to obtain a comparative heat-sensitive recording material.

Comparative Example 2 A heat-sensitive coating liquid having a weight ratio of liquid A: liquid E: liquid D: 14:l was applied and dried in the same manner as in Example 1 on the undercoat layer of Example 1, and then calendered. A comparative heat-sensitive recording material was obtained.

The heat-sensitive recording materials of the present invention and comparative heat-sensitive recording materials obtained as described above were printed using a commercially available thermal gradient tester) at 150°C for 1 second, and the image density and background density were measured. RD514 (#106); Measured with one change of course.

Further, a small amount of cottonseed oil was applied to the image and the background of the obtained recording paper, and the paper was left in a dry environment at 40° C. for 24 hours, and changes in density were observed. (Oil resistance test). or,
Each recording paper was immersed in water for 24 hours and then dried to observe changes in image density (water resistance test).

The results are shown in Table-1.

Table-1

Claims (1)

[Claims] (1) In a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, the color developer may be of the following general formula (
In addition to using an N-vinylimidazole complex of zinc halide represented by I), the following general formula (I) is used as an auxiliary agent:
A heat-sensitive recording material characterized by using a phenolic compound represented by II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, X represents a halogen atom.) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II)