JP2001301338A - Heat sensitive recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording body, having a high sensitivity and hardly causing the blushing of skin substantially while capable of providing a recording characteristic prominent in the storage stability of a recorded image and, especially, in resistance to moisture, resistance to heat and resistance to plasticizing agent. SOLUTION: The heat sensitive recording body employs the mixed composite of 2,4-bis(phenyl sulfonyl)-5-methyl phenol and 4,4'-dihydroxy-diphenylsulfone as a color developing agent and, further, employs at least one kind selected among groups consisting of β-naphthyl benzyl ester, stearic acid amide, dibenzyl oxalate, di-(p-methyl benzyl) oxalate, di-(p-chlorobenzoyl), 1,2-bis(3-methyl phenoxy)ethane, 1,-2-bis(4-methyl phenoxy)ethane and 1,2-bis(phenoxy)ethane as a sensitizer combined with the color developing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for developing a thermosensitive recording medium using a specific sulfonyl compound mixture as a developer.
Further, the present invention relates to a heat-sensitive recording material having a high sensitivity by combining this with a specific sensitizer and having almost no background fog and having excellent storage stability of recorded images, especially excellent in moisture resistance, heat resistance and plasticizer resistance. Things.

[0002]

2. Description of the Related Art A thermosensitive recording material utilizing a thermal coloring reaction between a basic dye precursor and an electron-accepting developer has been well known. Among them, 2,2-bis (4-
(Hydroxy-phenyl) propane and 4-hydroxy-
4'-Isopropoxy-diphenyl sulfone is well known (for example, Japanese Patent Publication No. 3-54555).

However, heat-sensitive recording materials using these materials have been required to be further improved in storage stability of color images, particularly in moisture resistance, heat resistance and plasticizer resistance.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide recording characteristics which are high in sensitivity and hardly cause background fog, and which are excellent in storage stability of a recorded image, especially excellent in moisture resistance, heat resistance and plasticizer resistance. The object of the present invention is to provide a thermosensitive recording medium that can be used.

[0005]

According to the present invention, a thermosensitive recording medium utilizing a color development reaction between an electron-donating basic dye precursor and an electron-accepting color developing agent contains 2,4 as a color developing agent. A heat-sensitive recording material comprising a mixed composition of -bis (phenylsulfonyl) -5-methylphenol and 4,4'-dihydroxy-diphenylsulfone is provided.

[0006]

Embodiments of the present invention will be described below in detail.

The present inventors have repeatedly studied to obtain a thermosensitive recording medium having high sensitivity and excellent preservation of a recorded image, and as a result, 2,4-bis (phenylsulfonyl) was used as a color developer.
A mixed composition of -5-methylphenol and 4,4'-dihydroxy-diphenylsulfone, and as a sensitizer, β-naphthylbenzyl ether, stearic acid amide, dibenzyl oxalate, oxalic acid-di- (P-
Methylbenzyl), di- (p-chlorobenzyl) oxalate, 1,2-bis (3-methylphenoxy) ethane,
1,2-bis (4-methylphenoxy) ethane and 1,
The present invention has been achieved by using a combination of at least one selected from the group consisting of 2-bis (phenoxy) ethane.

Here, a recording material using the thermosensitive recording medium according to the present invention will be described in detail.

As a color developer according to the present invention, 2,4-
The mixing ratio (weight ratio) of the combination of bis (phenylsulfonyl) -5-methylphenol and 4,4′-dihydroxy-diphenylsulfone is preferably 95: 5 to 5:95, more preferably 85:15 to 15: : 85, more preferably 80:20 to 20:80. The total amount of the composition used as a developer is 10% of the basic dye.
The amount is preferably 50 to 600 parts by weight, more preferably 100 to 400 parts by weight, based on 0 parts by weight.

[0010] The compounding method is as follows: (a) a method of mixing and pulverizing each compound at a desired ratio; (b) a method of mixing and pulverizing at the desired ratio during pulverization; Either melt-mixing in advance and solidifying by cooling, or a method of pulverizing a material prepared to a desired ratio by a recrystallization method using a solvent, or the like may be used.

Next, the sensitizer used in combination with the developer according to the present invention includes, for example, stearic acid amide, ethylenebisamide stearate, m-terphenyl,
Benzyl biphenyl, p-tolyl biphenyl ether,
Bis (p-methoxyphenoxyethyl), β-naphthylbenzyl ether, dibenzyl oxalate, di- (p-methylbenzyl) oxalate, di- (p-chlorobenzyl) oxalate, 1,2-bis (3 -Methylphenoxy)
Ethane, 1,2-bis (4-methylphenoxy) ethane, 1,2-bis (phenoxy) ethane, 1- (2-naphthyloxy) -2-phenoxyethane, diphenylsulfone, dimethyl terephthalate, dibutyl terephthalate and Examples include at least one selected from the group consisting of dibenzyl terephthalate and the like, and particularly preferably β-
Naphthylbenzyl ether, stearamide, dibenzyl oxalate, di- (p-methylbenzyl) oxalate, di- (p-chlorobenzyl) oxalate, 1,2
At least one selected from the group consisting of -bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane and 1,2-bis (phenoxy) ethane
Is a seed. The total amount of the sensitizer used is 100 basic dyes.
The amount is preferably 20 to 800 parts by weight, more preferably 50 to 400 parts by weight with respect to parts by weight.

The basic dyes include triarylmethane compounds, diarylmethane compounds, pyridine compounds, spiro compounds, rhodamine-lactam compounds, fluorane compounds, indolylphthalide compounds and fluorene compounds. Compounds and the like are exemplified. Among them, 3
-N, N-dibutylamino-6-methyl-7-anilinofluoran, 3-N, N-diethylamino-6-methyl-7-anilinofluoran, 3- (N-isopentyl-
N-ethyl) -6-methyl-7-anilinofluoran;
3- (N-cyclohexyl-N-methyl) -6-methyl-7-anilinofluoran, 3-N, N-diethyl-6
-Chloro-7-anilinofluoran and crystal violet lactone are exemplified as typical examples.
These basic dyes may be used alone or in combination of two or more kinds for the purpose of adjusting the color tone of a color-developed image or obtaining a multicolor heat-sensitive recording material.

As the pigment, pigments generally used for thermosensitive recording media, for example, kaolin, silica, amorphous silica, calcined kaolin, zinc oxide, calcium carbonate, aluminum hydroxide, magnesium carbonate, titanium oxide, barium sulfate And inorganic fine powders such as synthetic aluminum silicate,
It may be allowed to coexist with a fine powder of organic resin such as styrene-methacrylic acid copolymer, polystyrene resin and urea-formalin resin. The amount of these pigments used is the basic dye 1
With respect to 00 parts by weight, 10 to 2000 parts by weight is preferable,
More preferably, it is 20 to 1000 parts by weight.

Examples of the metal soap include zinc stearate, calcium stearate, and aluminum stearate.

Further, as the wax, candelilla wax, rice wax, wood wax, beeswax, lanolin, montan wax, carnauba wax, ceresin wax, paraffin wax, microcrystalline wax, natural wax such as tallow and coconut oil, and further, Natural waxes such as polyethylene wax, montan wax, carnauba wax, microcrystalline wax and tallow and coconut oil, derivatives such as polyethylene wax, montan wax, carnauba wax, microcrystalline wax, and stearic acid, and Fischer-Tropsch wax. it can. These may be used alone or as a mixture.

Examples of the surfactant include an alkali metal salt of sulfosuccinic acid, an alkali metal salt of alkylbenzenesulfonic acid, and a sodium salt of lauryl alcohol sulfate.

As the dispersant, sodium polyacrylate,
Examples thereof include polyvinyl alcohol (having various degrees of saponification, pH and polymerization degree), carboxymethylcellulose, hydroxyethylcellulose, polyacrylamide, starch, and ammonium salt of styrene-maleic anhydride copolymer.

If necessary, water-resistant improvers such as 1,1
1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane and 4-benzyloxy -4'-2,
3-propoxy-diphenyl sulfone or the like may be used.

Further, as a light resistance improving agent, a benzotriazole-based ultraviolet absorber, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole,
-(2-hydroxy-3-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2,2
-Methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] and microencapsulated 2-
(2-hydroxy-3-dodecyl-5-methylphenyl) benzotriazole or the like may be used.

The heat-sensitive recording layer according to the present invention can be manufactured by a known method, and it is not necessary to adopt any special method. For example, a basic dye, a developer, a sensitizer, a wax, a pigment, a metal soap, and the like are usually 5 μm or less in an aqueous medium containing a surfactant, an antifoaming agent, a dispersant, and the like by means of a ball mill, a sand mill, or the like. , Preferably 1.
Each coating liquid can be prepared by pulverizing and dispersing to a particle size of 5 μm or less. Further, the heat-sensitive recording layer can be formed according to a conventionally known technique, and the forming method is not particularly limited. For example, a coating solution for the heat-sensitive recording layer is coated on a support with a suitable coating device such as an air knife coater, a blade coater, a bar coater, a rod coater, a gravure coater, a curtain coater, and a wire bar, and dried to form a recording layer. Can be formed. There is no particular limitation on the coating amount of the coating solution, and the dry weight is generally 0.5 to 50 g with respect to the support surface.
r / m ² is preferred, and more preferably 1.0 to 20.0
gr / m ² . As the support, paper, plastic sheet, synthetic paper and the like are used.

Further, an undercoat layer may be provided in order to enhance color development sensitivity. The material of the undercoat layer mainly comprises a pigment or organic hollow particles and an adhesive. Examples of the pigment include calcined kaolin, magnesium carbonate, amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, calcium carbonate, and urea-formalin resin filler. The organic hollow particles include vinyl chloride, vinylidene chloride, vinyl acetate, methyl acrylate,
Examples of the resin include homopolymer or copolymer resins such as ethyl acrylate, methyl methacrylate, acrylonitrile, and styrene. Further, as an adhesive, gelatin, casein, starch and its derivatives, methylcellulose,
Ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methoxy cellulose, completely (partially) saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, allylic amide-ethyl acrylate copolymer, styrene Water-soluble polymers such as maleic anhydride copolymers and hydrophobic polymers such as styrene-butadiene resins, styrene-acrylic resins, vinyl acetate resins, and acrylic resins are exemplified.
Further, the formation of the undercoat layer is not particularly limited, and can be formed, for example, in the same manner as the above-described thermosensitive recording layer.

Further, a protective layer may be provided on the heat-sensitive recording layer for the purpose of further improving the storage stability and the like. Such a protective layer,
An adhesive having a film forming property, a pigment or the like may be used as a main component, and an ultraviolet absorber or the like may be used as necessary.

Examples of the adhesive having a film forming property include carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol.
On the other hand, as the pigment and the ultraviolet absorber, those of the above-described heat-sensitive recording layer may be used.

The formation of the protective layer is not particularly limited. For example, the protective layer can be formed in the same manner as the above-described thermosensitive recording layer.

In the heat-sensitive recording medium of the present invention, a protective layer may be provided on the back side of the support, if necessary, or a natural rubber, an acrylic resin-based adhesive, a styrene isoprene block polymer and a two-component cross-linkable type. An adhesive layer containing an acrylic resin-based adhesive as a main component may be provided, or a smoothing process such as super calendering may be performed after the application of each layer.

[0026]

The present invention will be described below in more detail with reference to specific examples.

(Example 1) <Preparation of basic dye dispersion> 30 gr of 3-N, N-dibutylamino-6-methyl-7-anilinofluorane was added to
Concentration 5% polyvinyl alcohol (trade name: PVA-11)
7, Kuraray Co., Ltd.) A basic dye dispersion having an average particle size of 1.0 μm was prepared by pulverizing in a 70 gr aqueous solution using a sand grinder (TSG4H, manufactured by Igarashi Kikai Co., Ltd.).

<Preparation of sensitizer dispersion> 1,2-bis (3
-Methylphenoxy) ethane in a grinder of 70% in a 5% aqueous solution of polyvinyl alcohol (PVA-117) using a sand grinder to obtain an average particle diameter of 1.
A 0 μm sensitizer dispersion was prepared.

<Preparation of developer dispersion> {Developer-1} 2,4-bis (phenylsulfonyl)-
30 gr of 5-methylphenol was pulverized with a sand grinder in 70 gr of a 5% aqueous solution of methylcellulose (trade name: Metroose 60SH-03, manufactured by Shin-Etsu Chemical Co., Ltd.) using a sand grinder to obtain a developer having an average particle size of 1.0 μm. Was prepared.

{Developer-2} Next, 30 gr of 4,4'-dihydroxy-diphenylsulfone was pulverized with a sand grinder in 70 gr of a 5% aqueous methylcellulose solution to develop a color having an average particle size of 1.0 μm. A dispersion of Agent-2 was prepared.

<Preparation of Pigment Dispersion> Calcium carbonate (trade name: Univer 70, manufactured by Shiraishi Industry Co., Ltd.) 30 gr, water 69
Gr and 40% aqueous sodium hexametaphosphate solution
0 gr was stirred for 5 minutes with a homogenizer (TK homodisper L type, manufactured by Tokushu Kika Co., Ltd.) having a rotation speed of 5000 rpm to prepare a pigment dispersion.

<Preparation of coating solution for heat-sensitive recording layer> 3.6 g of the basic dye dispersion described above, 7.2 g of the sensitizer dispersion, 3.6 g of the dispersion of the developer 1 and 3.6 g of the dispersion of the developer 2 were prepared. 3.6 g dispersion
and 7.2 g of pigment dispersion and hydrin Z-7 having a zinc stearate emulsion concentration of 30% as a lubricant dispersion.
Using 1.8 gr (trade name of Chukyo Yushi Co., Ltd.), then a 5% aqueous solution of polyvinyl alcohol (PVA-117) 2
1.6 gr was mixed to obtain a thermosensitive recording layer coating solution.

<Preparation of Thermosensitive Recording Paper> The coating solution of the thermosensitive recording layer was applied on a paper support surface using a wire bar so that the weight of the dried thermosensitive recording layer was 5 gr / m ^2, and the temperature was 60 ° C.
After drying in an oven, a calendering treatment was performed so that the smoothness became 200 seconds (Beck method).

(Examples 2 to 9) A heat-sensitive recording medium was prepared in the same manner as in Example 1 except that the respective dispersions of Example 1 were changed as follows.

Example 2 As a color developer, 2.9 gr of a dispersion of a color developer-1 and 4.3 g of a dispersion of a color developer-2 were used.
r, as a sensitizer, 3.6 g of a sensitizer dispersion and high micron G having a stearamide concentration of 21%.
The same operation as in Example 1 was carried out except that 5.1 gr of -270 (trade name, manufactured by Chukyo Yushi Co., Ltd.) was used.

Example 3 As a color developer, 4.3 gr of a dispersion of a color developer-1 and 2.9 g of a dispersion of a color developer-2 were used.
r, 30 g of the sensitizer 1,2-bis (3-methylphenoxy) ethane of Example 1 and 15 g of oxalic acid-di- (p-methylbenzyl) and oxalic acid-di- (p -Chlorobenzyl) The same operation as in Example 1 was carried out, except that the combined use with 15 gr was used, and 7.2 gr of the obtained sensitizer dispersion was used.

Example 4 As a sensitizer, the sensitizer 1,2-bis (3-methylphenoxy) ethane 30 of Example 1 was used.
The same operation was performed in the same manner as in Example 1 except that 30 gr of β-naphthylbenzyl ether was used instead of gr and 7.2 gr of the obtained sensitizer dispersion was used.

Example 5 As a color developer, 5.0 gr of a dispersion of a color developer-1 and 2.2 g of a dispersion of a color developer-2 were used.
r, as a sensitizer, the same operation was carried out by replacing 30 gr of the sensitizer 1,2-bis (3-methylphenoxy) ethane of Example 1 with 30 gr of 1,2-bis (4-methylphenoxy) ethane, The same operation as in Example 1 was carried out except that 7.2 gr of the obtained sensitizer dispersion was used.

Example 6 As a color developer, 5.8 gr of a dispersion of a color developer-1 and 1.4 gr of a dispersion of a color developer-2 were used.
The same procedures as in Example 1 were followed, except that they were used.

Example 7 As a sensitizer, the sensitizer 1,2-bis (3-methylphenoxy) ethane 30 of Example 1 was used.
The same operation was performed in the same manner as in Example 1, except that 30 gr of 4-benzylbiphenyl was used instead of gr and 7.2 gr of the obtained sensitizer dispersion was used.

Example 8 As a sensitizer, the sensitizer 1,2-bis (3-methylphenoxy) ethane 30 of Example 1 was used.
The same operation was carried out except that 30 gr of m-terphenyl was used instead of gr, and 7.2 gr of the obtained sensitizer dispersion was used.
The operation was performed in the same manner as in Example 1.

Example 9 As a sensitizer, the sensitizer 1,2-bis (3-methylphenoxy) ethane 30 of Example 1 was used.
The same operation was carried out except that 30 gr of diphenylsulfone was used instead of gr, and 7.2 gr of the obtained sensitizer dispersion was used.
The operation was performed in the same manner as in Example 1.

(Comparative Examples 1 to 5) A heat-sensitive recording material was produced in the same manner as in Example 1 except that the respective dispersions of Example 1 were changed as follows.

Comparative Example 1 As a color developer, 2,4-bis (phenylsulfonyl) -5--5 of the color developer-1 of Example 1 was used.
A developer dispersion 7.2 gr obtained by the same operation except that 30 gr of methylphenol was replaced with 30 gr of 2,2-bis (4-hydroxy-phenyl) propane was used.
On the other hand, the operation was carried out in the same manner as in Example 1, except that the developer-2 dispersion was not used.

(Comparative Example 2) As a color developer, 7.2 gr of a dispersion of a color developer-1 was used, and a dispersion of a color developer-2 was not used. On the other hand, the same operation as in Example 1 was carried out except that 7.2 gr of the sensitizer dispersion of Example 4 was used instead of that of Example 1 as a sensitizer.

(Comparative Example 3) As a developer, 7.2 gr of a dispersion of developer-2 was used, and a dispersion of developer-1 was not used. On the other hand, the same operation as in Example 1 was carried out except that 7.2 gr of the sensitizer dispersion of Example 3 was used instead of that of Example 1 as a sensitizer.

(Comparative Example 4) As a developer, 3.6 gr of the dispersion of the developer-1 of Example 1 was used, and the developer of the comparative example 1 was used instead of the dispersion of the developer-2. 3.6 gr of the dispersion was used. Further, the same operation as in Example 1 was carried out except that 7.2 gr of the sensitizer dispersion of Example 4 was used instead of that of Example 1 as a sensitizer.

(Comparative Example 5) As a developer, 3.6 gr of the developer-2 dispersion of Example 1 was used, while the developer-1 dispersion was 2,4-bis ( Phenylsulfonyl)
30 g of 4-hydroxy-4′-isopropoxy-diphenyl sulfone in place of 30 gr of 5-methylphenol
and 3.6, a developer dispersion obtained in the same manner as described above.
The same operation as in Example 1 was performed except that gr was used.

Next, the heat-sensitive recording papers obtained in Examples 1 to 9 and Comparative Examples 1 to 5 were applied to a heat-sensitive paper coloring tester <TH-PMD.
> Thermal head (KYOCERA.T) made by Okura Electric Co., Ltd.
YPE KJT-256-8MGFI-ASH) 165
Using 3Ω, printing voltage 24V, printing cycle 1.4msec
A printing test was performed, and the following performance comparison test was performed. Table 1 shows the results.

<Performance Comparison Test> (1) Print Density and Background The print density was measured using a Macbeth densitometer (TH-PMD type, manufactured by Macbeth). (2) Moisture resistance test The background fog and the print density after leaving for 24 hours at a temperature of 40 ° C. and a humidity of 90% were measured with a Macbeth densitometer. (3) Heat resistance test The background fog and print density after standing at 60 ° C. for 24 hours were measured with a Macbeth densitometer. (4) Plasticizer resistance test A printing paper was wound around the outer periphery of the glass bottle, and a high wrap V-450 (trade name, manufactured by Mitsui Toatsu Chemicals) was wound three times on the printing paper and left at 40 ° C for 3 hours. Thereafter, the print density was measured with a Macbeth densitometer.

[0051]

[Table 1]

As described above, the heat-sensitive recording material according to the present invention has excellent coloring properties, has almost no background fog over time,
It can be seen that the storage stability of the recorded image is particularly excellent in heat resistance, moisture resistance, and plasticizer resistance, and that the thermosensitive recording medium is extremely well-balanced.

[0053]

According to the present invention, high sensitivity, almost no background fog over time, preservation of recorded images, especially heat resistance,
It has become possible to provide a thermosensitive recording medium having excellent moisture resistance and plasticizer resistance.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Takaguchi 1-10-24, Itokaichi, Ibaraki-shi, Osaka Sanko Co., Ltd., Factory Products Division Research Institute (72) Inventor Takaaki Mori 1-chome, Itokaichi, Ibaraki-shi, Osaka No. 10-24 Sanko Co., Ltd. F-term in the Research Laboratory of Factory Products Division (Reference) 2H026 AA07 BB25 BB28 BB39 DD02 DD12 DD14 DD19 DD43 DD45 DD53

Claims (3)

[Claims] 1. A thermosensitive recording medium utilizing a color development reaction between an electron-donating basic dye precursor and an electron-accepting color developer, wherein 2,4-bis (phenylsulfonyl) -5 is used as a color developer. −
A heat-sensitive recording material comprising a mixed composition of methylphenol and 4,4'-dihydroxy-diphenylsulfone. 2. A 2,4-bis (phenylsulfonyl)-
The mixing ratio (weight ratio) of 5-methylphenol and 4,4'-dihydroxy-diphenylsulfone is 95: 5
The heat-sensitive recording material according to claim 1, comprising a developer composition of 5:95. 3. The heat-sensitive recording medium further comprises β as a sensitizer.
-Naphthylbenzyl ether, stearamide, dibenzyl oxalate, di- (p-methylbenzyl) oxalate, di- (p-chlorobenzyl) oxalate, 1,2
At least one selected from the group consisting of -bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane and 1,2-bis (phenoxy) ethane
The thermosensitive recording medium according to claim 1, further comprising a seed.