JPH05116458A - Thermal recording body - Google Patents

Abstract

PURPOSE:To obtain a thermal recording body with improved stability of a recording image by providing a heat-sensitive recording layer contg. a specified basic dye and a specified color-developing agent which develops color when it is brought into contact with this dye on a supporting body. CONSTITUTION:A coating liq. for a thermal recording layer contg. each specified amt. of a colorless or light-color basic dye of formula [wherein R1 and R2 are each halogen atom, a 1-4C alkyl group or a 1-25C alkoxy group; R3 is a 1-25C alkyl group, a 1-25C alkoxyalkyl group, phenyl group or benzyl group; m and n are each integer of 0, 1 or 2] and 4,4-cyclohexylidene-diphenol as a color developing agent is prepd. After a supporting body such as a paper and a plastic film is coated with this coating liq. for thermal recording layer, it is dried to form a thermal recording layer and to obtain a thermal recording body. In addition, it is possible to improve storage stability by providing a protective layer on 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 excellent in the stability of recorded images.

[0002]

2. Description of the Related Art A heat-sensitive recording material which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic color-forming agent to bring a recording image by contacting both color-forming substances with heat is often used. Are known. Such a thermal recording material is relatively inexpensive,
Since the recording device is compact and easy to maintain, it is used not only as a recording medium for facsimiles and various computers, but also in a wide range of fields. In recent years, a thermal recording material is often used also as an output for a word processor, and a thermal recording paper which develops various colors such as red and blue has been demanded.

[0003]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted various studies to provide a heat-sensitive recording material that develops yellow, but a basic dye that develops yellow in general has a low coloring density and is resistant to light of a colored image. Inferior in sex. Also, JP-A-59-1528
No. 91 and JP-A-62-70081 exemplify basic dyes of yellow coloration which are excellent in light resistance, and it has been found that these dyes cause remarkable fading after printing.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied to provide a heat-sensitive recording material using a yellow-coloring basic dye excellent in stability of a recorded image, and as a result, as a result, They have found that the problem can be solved by combining a coloring agent.

That is, the present invention provides a thermosensitive recording medium comprising a support and a thermosensitive recording layer containing a colorless or light basic dye and a coloring agent capable of coloring when contacted with the dye. The heat-sensitive recording material is characterized by using the following general formula [Chemical Formula 1] as a functional dye and 4,4'-cyclohexylidenediphenol as a colorant.

[0006]

[Chemical 1]

(Wherein R ₁ and R ₂ are halogen atoms, and C ₁ to
C ₄ alkyl group, C ₁ -C ₂₅ alkoxy group,
R ₃ represents a C _{1 to} C ₂₅ alkyl group, a C _{1 to} C ₂₅ alkoxyalkyl group, a C _{1 to} C ₂₅ halogenoalkyl group, an optionally substituted phenyl group, or an optionally substituted benzyl group, m and n show the integer of 0, 1, and 2. )

[0008]

Specific examples of the basic dye represented by the general formula [Chemical Formula 1] used in the present invention include 1- (4-methoxyphenyl) -2- (2-quinolyl) ethylene and 1- (4- Octoxyphenyl) -2- (2-quinolyl) ethylene,
1- (3-methoxy-4-lauryloxyphenyl)-
2- (2-quinolyl) ethylene, 1- (4-methoxyphenyl-2- (6-ethoxy-2-quinolyl) ethylene, 1- (4-myristyloxyphenyl) -2- (2-
Examples thereof include compounds such as quinolyl) ethylene and 1- (3-methoxy-4-myristyloxyphenyl) -2- (6-ethoxy-2-quinolyl) ethylene, but are not limited to these compounds, and are generally Two or more compounds represented by the formula [Chemical Formula 1] may be used in combination.

The present invention is characterized in that the basic dye represented by the general formula [Chemical Formula 1] is used in combination with the coloring agent 4,4'-cyclohexylidene diphenol. The use ratio of the basic dye and the colorant is not particularly limited, but about 150 to 2000 parts by weight, preferably 250 to 1500 parts by weight of the colorant is used with respect to 100 parts by weight of the basic dye. .. If the coloring agent is less than 150 parts by weight, it becomes difficult to obtain sufficient stability of the recorded image. It is also possible to use other known basic dyes and colorants in combination within the range that does not impair the effects of the present invention.

In the present invention, a coating solution containing the basic dye of the general formula [Chemical Formula 1] and a specific coloring agent is generally prepared by using water as a dispersion medium, and a ball mill, attritor, vertical or horizontal sand mill, colloid mill, etc. With the stirring and crushing machine of
It is prepared, for example, by dispersing a dye, a coloring agent and a heat-fusible substance together or separately.

In such a coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy group-modified polyvinyl alcohol, sulfone group-modified polyvinyl alcohol, acetoacetyl are usually used as binders. Various modified polyvinyl alcohols such as group-modified polyvinyl alcohol and silicon-modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid Copolymer salt, styrene / butadiene copolymer emulsion, colloidal silica particle composite styrene / acrylic ester copolymer emulsion, urea resin, melamine resin, amide resin There 1 to 40 weight percent of total solids, and preferably amount of about 5 to 25 wt%. Of course, it is also possible to use two or more kinds of these binders.

Further, various auxiliaries can be added to the coating solution, for example, 2,2'-methylenebis (4,6-
Mixture of sodium salt of di-tert-butylphenyl) phosphate and magnesium silicate, dioctylsulphosuccinic acid sodium salt, sodium dodecylbenzenesulfonic acid salt, lauryl alcohol sulfate / sodium salt, dispersant such as fatty acid metal salt, benzophenone system,
Examples include cyanoacrylate-based and hydroxybenzoate-based ultraviolet absorbers, other defoaming agents, fluorescent dyes, coloring dyes, and the like.

Further, stearic acid ester wax, polyethylene wax, carnauba wax, microcrystalline wax, so as to prevent the thermal recording material from sticking due to contact with a recording device or recording head.
It is also possible to add a dispersion or emulsion of carboxy-modified paraffin wax, zinc stearate, calcium stearate or the like.

In addition, kaolin, clay, talc, calcium carbonate,
Magnesium carbonate, calcined clay, titanium oxide, diatomaceous earth,
Inorganic pigments such as particulate anhydrous silica and activated clay, organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch granules can also be added.

Further, in the heat-sensitive recording material of the present invention, fatty acids such as stearic acid amide, stearic acid methimon bisamide, oleic acid amide, palmitic acid amide, and coconut fatty acid amide are used as long as the desired effects of the present invention are not impaired. Amide, 4,4'-butylidene bis (6-tert
-Butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4)
Hindered phenols such as -hydroxy-5-cyclohexylphenyl) butane, m-terphenyl, p-benzylbiphenyl, p- (4-tolyloxy) biphenyl, 1,5-bis (4-methoxyphenoxy) -3-oxa -Pentane, 1,2-bis (phenoxy) ethane,
1,2-bis (4-methylphenoxy) ethane, 1,2
-Bis (3-methylphenoxy) ethane, 1- (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, ethers such as 2-naphtholbenzyl ether, dibenzyl terephthalate, 1-hydroxy-2-
Naphthoic acid phenyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester, etc., 2- (2'-hydroxy-5'-methylphenyl) )
An ultraviolet absorber such as benzotriazole and 2-hydroxy-4-benzyloxybenzophenone and various known heat-fusible substances can be used together as a sensitizer.

The amount of the heat-fusible substance contained in the recording layer is not limited, but is preferably 50 to 100 parts by weight of the basic dye.
The amount is 500 parts by weight, more preferably 100 to 300 parts by weight.

In the heat-sensitive recording material of the present invention, the method for forming the recording layer is not particularly limited, and the recording layer can be formed according to a conventionally known and commonly used technique. For example, the coating liquid for the heat-sensitive recording layer is coated on a support with an appropriate coating device such as an air knife coater, a blade coater, a bar coater, a die coater, a gravure coater, and a curtain coater, and dried to form a recording layer.

The coating amount of the coating liquid is not particularly limited, and generally 1.0 to 12 g / m 2 in dry weight.
It is adjusted in the range of about ² , preferably 1.5 to 10 g / m ² .

As the support, paper, plastic film, synthetic paper or the like is used, but paper is most preferably used in terms of cost and coating suitability. When synthetic paper is used, it is more preferable that the color density is high and the image quality is high, but there is also a drawback that the cost becomes high.

In the present invention, a protective layer may be formed on the heat-sensitive recording layer to enhance the storage stability. Examples of the water-soluble or water-dispersible polymer used for forming the protective layer include various binders as described above.
Among them, acetoacetyl group-modified polyvinyl alcohol and carboxyl group-modified porvinyl alcohol are particularly preferably used because they form a strong film.

A pigment may be added to the protective layer, if necessary, in order to further improve printability and sticking. Specific examples thereof include calcium carbonate,
Inorganic pigments such as zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined kaolin, and colloidal silica, styrene microballs, nylon powder, polyethylene powder, ureapolmarin. Examples include resin fillers and organic pigments such as raw starch particles. The amount used is generally 5 to 5 with respect to 100 parts by weight of the resin component.
It is desirable to adjust within the range of about 00 parts by weight.

Furthermore, in the coating liquid for forming the protective layer, zinc stearate, calcium stearate,
Lubricants such as polyethylene wax, carnauba wax, paraffin wax and ester wax; surfactants (dispersants, lubricants) such as sodium dioctylsulfosuccinate; antifoaming agents; water-soluble polyvalent salts such as potassium alum and calcium acetate. Various auxiliaries can also be added as appropriate.
Further, a curing agent such as glyoxal, boric acid, dialdehyde starch, or an epoxy compound may be added to further improve water resistance. The coating liquid for forming the protective layer is generally prepared using water as a dispersion medium.

The coating solution for protective layer thus prepared is coated on the thermosensitive recording layer by an appropriate coating layer, but when the coating amount exceeds 20 g / m ² in dry weight, the recording sensitivity of the thermosensitive recording medium is remarkably lowered. Generally, 0.1-20
g / m ^2, preferably it is desired to be adjusted in the range of about 0.5 to 10 g / m ^2.

The heat-sensitive recording material of the present invention may be a multi-color heat-sensitive recording material by combining heat-sensitive recording layers that develop different color tones. Further, if necessary, a protective layer may be provided on the back side of the thermosensitive recording medium to further improve the storability. Furthermore, it is also possible to provide an undercoat layer between the support and the heat-sensitive recording layer, or to perform super calendering after coating each layer, and also to give a pressure-sensitive adhesive treatment on the back surface of the recording medium to process it into a pressure-sensitive adhesive label, etc. Various known techniques in the field of manufacturing thermal recording media can be added as necessary.

[0025]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, "part" and "%" in an example show "weight part" and "weight%", respectively, unless there is particular notice.

Example 1 Formation of Intermediate Layer Calcined clay (trade name: Ansilex, manufactured by EMC) 1
A composition comprising 00 parts, 15 parts of a styrene-butadiene copolymer latex (solid content: 50%), 30 parts of a 10% polyvinyl alcohol aqueous solution, and 200 parts of water is mixed,
A coating liquid for the intermediate layer was prepared. 50 g / m ^{2 of the} obtained coating liquid
Was coated and dried to give a dry weight of 7 g / m ² to form an intermediate layer.

Preparation of Solution A 1- (3-methoxy-4-lauryloxyphenyl)-
A composition comprising 10 parts of 2- (2-quinolyl) ethylene, 25 parts of 1,2-bis (3-methylphenoxy) ethane, 15 parts of a 5% aqueous solution of methylcellulose, and 35 parts of water was used, and the average particle size was adjusted to 0. It was crushed to 8 μm.

Preparation of Solution B 4,4′-Cyclohexylidenediphenol 30 parts, 5
% 15% aqueous solution of methyl cellulose and 45 parts of water were pulverized with a sand mill until the average particle size became 1.1 μm.

Formation of Thermosensitive Recording Layer 85 parts of solution A, 90 parts of solution B, 35 parts of light calcium carbonate,
80% 10% aqueous polyvinyl alcohol solution, 100 parts 20% aqueous oxidized starch solution, 30% zinc stearate dispersion 4
0 part and 170 parts of water were mixed and stirred to obtain a coating liquid. The resulting coating liquid was applied onto the above intermediate layer so that the dry weight was 5 g / m ^2, and dried to obtain a thermosensitive recording medium.

Example 2 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 20 parts were used instead of 30 parts of 4,4'-cyclohexylidenediphenol in the preparation of solution B.

Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 10 parts were used instead of 30 parts of 4,4'-cyclohexylidenediphenol in the preparation of solution B.

Example 4 In the preparation of solution A, 1- (4-myristyloxyphenyl) -2- was used instead of 1- (3-methoxy-4-lauryloxyphenyl) -2- (2-quinolyl) ethylene.
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (2-quinolyl) ethylene was used.

Comparative Examples 1 and 2 In the preparation of solution B, bisphenol A (Comparative Example 1) was used instead of 4,4'-cyclohexylidene diphenoke.
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 4-hydroxy-4'-isopropyloxydiphenyl sulfone (Comparative Example 2) was used.

Six types of thermal recording materials obtained as described above were recorded by a thermal transfer printing evaluation tester (resistance value 557Ω, applied voltage 12V, pulse width 4 ms). The obtained recorded image density was measured by a Macbeth reflection densitometer (RD-914 type, manufactured by Macbeth, yellow filter), and the results are shown in [Table 1]. Further, the density of the change over time (after 3 days) of the recorded image held in the room was measured again by the Macbeth reflection densitometer, and the results are also shown in [Table 1].

[0035]

[Table 1]

[0036]

As is clear from the results shown in Table 1, all of the thermal recording media obtained in the respective examples of the present invention were thermal recording media excellent in the stability of recorded images.

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support and a thermosensitive recording layer containing a colorless or light-colored basic dye and a coloring agent capable of coloring when contacted with the dye. A heat-sensitive recording material characterized by using the following general formula [Chemical formula 1] and using 4,4'-cyclohexylidenediphenol as a coloring agent. [Chemical 1] (In the formula, R ₁ and R ₂ represent a halogen atom, a C _{1 to} C ₄ alkyl group, and a C _{1 to} C ₂₅ alkoxy group, and R ₃ represents C ₁ to
C ₂₅ alkyl group, C ₁ -C ₂₅ alkoxyalkyl group, C ₁ -C ₂₅ halogenoalkyl group, optionally substituted phenyl group, optionally substituted benzyl group,
m and n show the integer of 0, 1, and 2. )