JPH05238151A - Thermosensitive recording medium - Google Patents

Abstract

PURPOSE:To provide a blue-coloring thermosensitive recording medium with excellent light fasteness. CONSTITUTION:A basic dye, a developer, at least, one type selected from among stearic acid, zinc stearate and calcium stearate, and 2,2'-methylene bis(4-methyl-6- tert-butylphenol) are added to a recording layer on a support. The basic dye is 3-(4-dimethylaminophenyl)-3-(4-dimethylamino-2-methylphenyl)-6- dimethylaminophthalide and/or 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording material, and more particularly to a blue color thermosensitive recording material having excellent light resistance.

[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]

The inventors of the present invention have made various studies to provide a blue color thermosensitive recording medium, but generally, 3,3-bis (p-dimethylaminophenyl) -6-, which is widely used. A basic dye that develops a blue color, such as dimethylaminophthalide, is inferior in light resistance of a color image. On the other hand, 3
-(4-Diethylamino-2-ethoxy) phenyl-3
-(1-Ethyl-2-methylindol-3-yl)-
If blue-based coloring dyes such as 4-azaphthalide and 3- (4-diethylamino-2-ethoxy) phenyl-3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide are used, the color is surely developed. Although the image has excellent light fastness, it has a drawback that when bisphenol A whose color tone is closer to dark blue than blue is used and bisphenol A which is low in cost is used as a color developing agent, the background fog is large.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted earnest research to provide a blue color thermosensitive recording material having excellent light resistance of a color image, and as a result, by using a specific compound in combination with a specific dye. I found that I could solve it. That is, the present invention provides a heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a colorless or light-colored basic dye and a color-forming agent capable of forming a color by contacting with the dye. 3- (4-Dimethylaminophenyl) -3- (4-diethylamino-2-methylphenyl) -6-dimethylaminophthalide and / or 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthali And at least one selected from stearic acid, zinc stearate and calcium stearate, and 2,
A heat-sensitive recording material comprising 2'-methylenebis (4-methyl-6-tert-butylphenol) in the recording layer.

[0005]

The function of the present invention is 2,2'-methylenebis (4-
Methyl-6-tert-butylphenol), and the use ratio of at least one of stearic acid, zinc stearate, and calcium stearate is not particularly limited, but is generally 5 to 5 parts by weight per 100 parts by weight of the basic dye.
It is desirable to use in an amount of 500 parts by weight, preferably 25 to 250 parts by weight. In particular, when 2,2′-methylenebis (4-methyl-6-tert-butylphenol) is used by making the average particle diameter to be 1.0 μm or less, the effect of the present invention becomes more remarkable.

Various compounds are known as a colorant used in combination with the specific basic dye used in the present invention, and examples thereof include the following. 4-tert-butylphenol, α-naphthol, β-naphthol, 4-acetylphenol, 4-tert-octylphenol,
4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, 4,
4'-isopropylidene diphenol, hydroquinone, 4,4'-cyclohexylidene diphenol, 4,
4 '-(1,3-dimethylbutylidene) bisphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis (6-tert -Butyl-3
-Methylphenol), 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-methoxydiphenylsulfone, 4-hydroxy-4. ′ -Isopropoxydiphenyl sulfone, 4-hydroxy-3 ′, 4′-trimethylene diphenyl sulfone, 4-hydroxy-3 ′, 4′-tetramethylene diphenyl sulfone, 3,4-dihydroxy-4′-methyldiphenyl sulfone, Bis (3-allyl-4-hydroxyphenyl) sulfone, 1,3-di [2- (4-hydroxyphenyl) -2-propyl] benzene, 1,1-bis (4-hydroxyphenyl) -1
-Phenylethane, hydroquinone monobenzyl ether, bis (4-hydroxyphenyl) acetic acid butyl ester, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2 ', 4 4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, 4
-Methyl hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate. Tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, p-methoxy 4-hydroxybenzoate. Phenolic compounds such as benzyl, novolac type phenol resin, phenol polymer, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-se
c-Butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-4
-Hydroxybenzoic acid, salicylic acid, 3-isopropylsalicylic acid, 3-tert-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-benzylsalicylic acid,
3- (α-methylbenzyl) salicylic acid, 3-chloro-
5- (α-methylbenzyl) salicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid, 3,
5-di-α-methylbenzyl salicylic acid, 4- (2-p
-Methoxyphenoxyethoxy) salicylic acid, 4- (3
-P-tolylsulfonylpropyloxy) salicylic acid,
Aromatic carboxylic acids such as 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid, and these phenolic compounds, aromatic carboxylic acids and, for example, zinc,
Organic acidic substances such as salts with polyvalent metals such as magnesium, aluminum, calcium, titanium, manganese, tin and nickel. As a matter of course, two or more kinds of the above-mentioned color developing agents can be used in combination. Above all, 4,4'-isopropylidenediphenol is the most preferable because it is inexpensive and easily available.

The use ratio of the basic dye and the color developing agent should be appropriately selected according to the type of the color developing agent and is not particularly limited, but generally 100 to 2000 per 100 parts by weight of the basic dye. Parts by weight, preferably 150-1500
About a part by weight of the coloring agent is used. The preparation of a coating liquid containing these is generally carried out by using water as a dispersion medium and dispersing the dye, the specific polyvalent metal salt, and the color former together or separately by a stirring / grinding machine such as a ball mill, an attritor or a sand mill. It is prepared, for example.

In such coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, sulfo group-modified polyvinyl alcohol, silicon modified polyvinyl alcohol are usually used as binders. ,
Acetoacetyl group-modified polyvinyl alcohol, graft copolymer of vinyl alcohol / vinyl acetate copolymer and acrylamide / acrylic acid / allyl acetoacetate copolymer, 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 acid ester copolymer emulsion, urea resin, melamine resin, amide resin, etc. are all solid 1-40% by weight, preferably 5-2
About 5% by weight is blended. Of course, it is also possible to use two or more kinds of these binders.

Further, various auxiliary agents can be added to the coating liquid, 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 recording equipment or recording head.
A dispersion liquid such as carboxy-modified paraffin wax or an emulsion may be added.

[0011] 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 acid amides such as stearic acid amide, stearic acid methylene 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. , 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 used is not particularly limited, but is generally 50 to 1000 parts by weight, preferably 100 to 500 parts by weight, based on 100 parts by weight of the basic dye. Is desirable.

In the thermosensitive recording medium 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 solution for the heat-sensitive recording layer is applied 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, a curtain coater, and a short dwell coater, and the recording layer is dried. To form.

Further, 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 .

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 as needed in order to further improve printability and sticking. Specific examples thereof include calcium carbonate and
Inorganic pigments such as zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined kaolin, colloidal silica, styrene microballs, nylon powder, polyethylene powder, urea formalin 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 a suitable coating layer. When the coating amount exceeds 20 g / m ² in dry weight, the recording sensitivity of the thermosensitive recording material 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 which 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 apply a super calendar after coating each layer, and various known techniques in the thermal recording material manufacturing field can be applied as necessary, such as applying an adhesive treatment to the back surface of the recording material and processing it into an adhesive label. It can be added.

[0020]

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 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide 10 parts, 1,2-bis (3-methylphenoxy) ethane 25 parts, 5% methylcellulose aqueous solution 15 parts, And a composition comprising 35 parts of water were pulverized with a sand mill until the average particle size became 0.8 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.

Preparation of Solution C 5 parts of 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 5% aqueous solution of methylcellulose 3
Part, 10% dioctylsulfosuccinic acid sodium salt aqueous solution 2 parts, and water 3 parts were pulverized with a horizontal sand mill until the average particle size became 0.7 μm.

Preparation of Recording Layer Liquid A 85 parts, liquid B 90 parts, liquid C 13 parts, light calcium carbonate (oil absorption 90 ml / 100 g) 30 parts, 20% polyvinyl alcohol aqueous solution 75 parts, 30% zinc stearate aqueous dispersion A coating liquid was obtained by mixing and stirring 15 parts of the liquid and 170 parts of water. The coating amount of the obtained coating liquid on the support was 5 after drying.
A thermosensitive recording material was obtained by coating and drying so as to obtain g / m ² .

Example 2 In the preparation of solution A, instead of 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide,
3- (4-dimethylaluminophenyl) -3- (4-diethylamino-2-methylphenyl) -6-dimethylaminophthalide was used, and calcium stearate was used instead of zinc stearate in the preparation of the recording layer. A thermal recording material was obtained in the same manner as in Example 1.

Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the average particle size was 1.2 μm in the preparation of the C liquid.

Example 4 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that stearic acid was used instead of zinc stearate in the preparation of the recording layer.

Comparative Example 1 In the preparation of solution C, 1,2'-methylenebis (4-methyl-6-tert-butylphenol) was replaced by 1,2'-methylenebis (4-methyl-6-tert-butylphenol).
1,3-tris (2-methyl-4-hydroxy-5-te
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that rt-butylphenyl) butane was used.

Comparative Example 2 In the preparation of solution C, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) was used instead of 2,2'-methylenebis (4-methyl-6-tert-butylphenol).
A thermosensitive recording medium was obtained in the same manner as in Example 2 except that 2'-methylenebis (4-ethyl-6-tert-butylphenol) was used.

Comparative Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that cadmium stearate was used instead of zinc stearate in the preparation of the recording layer.

Comparative Example 4 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that tin stearate was used instead of zinc stearate in the preparation of the recording layer.

The eight 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 with a Macbeth reflection densitometer (RD-914 type, manufactured by Macbeth, blue filter), and the results are shown in [Table 1]. As a light resistance test, the density of the recorded image held inside the south window for 2 days was measured again with a Macbeth reflection densitometer, and the results are also shown in [Table 1].

[0034]

[Table 1]

[0035]

As is clear from the results of [Table 1], the heat-sensitive recording materials obtained in the respective examples of the present invention were all heat-sensitive recording materials having excellent light resistance.

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. 3- (4-Dimethylaminophenyl) -3- (4-diethylamino-2-methylphenyl) -6-dimethylaminophthalide and / or 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthali And at least one selected from stearic acid, zinc stearate and calcium stearate, and 2,
A thermosensitive recording medium comprising 2'-methylenebis (4-methyl-6-tert-butylphenol) in the recording layer.