WO2003070480A1

WO2003070480A1 - Color developer and thermal recording material containing the same

Info

Publication number: WO2003070480A1
Application number: PCT/JP2003/001453
Authority: WO
Inventors: Fumio Oi; Norio Yanase; Nobuyuki Nate; Hiroyuki Yamamoto; Etsuzo Nagaoka; Masamichi Yamamoto; Yasuhisa Tsutsumi
Original assignee: Konishi Chemical Ind. Co., Ltd.; Nippon Steel Chemical Co., Ltd.
Priority date: 2002-02-22
Filing date: 2003-02-12
Publication date: 2003-08-28
Also published as: AU2003207086A1

Abstract

A color developer which comprises as a major ingredient a mixture of 4,4'-dihydroxydiphenyl sulfone and 2,4'-dihydroxydiphenyl sulfone in a ratio of from 90/10 to 10/90 by weight, and in which the content of phenyl phenolsulfonate is 1.5 wt.% or lower based on the mixture and/or the mixture dissolved has a color with a Hazen value less than 400.

Description

Description Developer and thermosensitive recording material containing the same

The present invention relates to a developer containing, as a main component, a mixture of 4,4, dihydroxydiphenylsulfone and 2,4,1-dihydroxydiphenylsulfone, and a thermosensitive recording material containing the developer. Things. Background art

Conventionally, thermosensitive recording paper (thermosensitive recording material) having a thermosensitive coloring layer containing a developer and a coloring dye has been used for various devices typified by information communication devices such as facsimile machines and information recording devices such as printers. Widely used as recording paper (output paper). The heat-sensitive recording paper must have high color-forming sensitivity (color-forming property), and high color image and background (portion where no color-formed image is formed) fastness for long-term storage (a small change with time). ) Are required.

For example, Japanese Patent Application Laid-Open No. 57-15059 (published date; September 17, 1982) and Japanese Patent Application Laid-Open No. 63-3991 (published date: 19 For example, 2,4'-dihydroxydiphenylsulfone and 4,4 'are used as developers with excellent storage stability for color images and background. , 4, - dihydric Dorokishijifue - _t Rusuruhon be used are disclosed, however, these color developers, color developing sensitivity is low and has a problem of poor storage depreciation qualitative color image. On the other hand, for example, Japanese Patent Application Laid-Open No. 2001-266054 (publication date; September 25, 2001) ゃ Japanese Patent Application Laid-Open No. 2001-2903964 Publication No. (publication date; October 23, 2001) uses a mixture of 4,4′-dihydroxydiphene-noresnorefone and 2,4, dihydroxydiphenylsnorehon as a developer Further, there is disclosed a thermosensitive recording material having a thermosensitive coloring layer containing the color developer and the sensitizer.

Japanese Patent Application Laid-Open Publication No. 2002-2012 (published date: April 23, 2002) discloses 4,4, dihydroxydiphenylsulfone and 2,4, A heat-sensitive recording material having a heat-sensitive coloring layer containing, as a color developer, a mixture obtained by mixing dihydroxydiphenyl sulfone with a specific ratio is disclosed.

However, the heat-sensitive recording material disclosed in Japanese Patent Application Laid-Open No. 2001-266504 and Japanese Patent Application Laid-Open No. 200-29364 is particularly inferior in whiteness of the background. (So-called background capri is produced) and the storage stability (moisture and heat resistance, water resistance, plasticizer resistance and heat resistance) is not sufficient. Further, the heat-sensitive recording material disclosed in Japanese Patent Application Laid-Open No. 2002-120462 is excellent in plasticizer resistance, but has a problem that the improvement particularly against background capri is not sufficient. have. In other words, the heat-sensitive recording materials described in the above-mentioned publication do not improve the storage stability of the background to the extent that they are sufficiently satisfactory for practical use.

In addition, the thermal recording paper currently on the market has a large change over time, such as the color image becomes thin and difficult to see when stored for a long period of time. That is, the currently available thermal recording paper has a problem that the above-mentioned various performances required for the thermal recording paper cannot be sufficiently satisfied. Therefore, there is a need for a heat-sensitive recording material that can sufficiently improve the background capri and that has excellent storage stability, and a developer that can be suitably used for the heat-sensitive recording material.

In addition, a heat-sensitive recording material having high color-forming sensitivity, excellent whiteness of the background, and excellent storage stability of a color-formed image and background, and a developer that can be suitably used for the heat-sensitive recording material are required. Have been.

The present invention has been made in view of the above-mentioned conventional problems, and a first object of the present invention is to provide a heat-sensitive material which has particularly low background capri and excellent storage stability such as wet heat resistance and water resistance (so-called weather resistance). An object of the present invention is to provide a recording material and a color developer which can be suitably used for the heat-sensitive recording material.

In addition, the present invention has been made in view of the above-mentioned conventional problems, and a second object of the present invention is to have high coloring sensitivity, excellent whiteness of the background, and excellent storage stability of the coloring image and the background. Another object of the present invention is to provide a heat-sensitive recording material and a color developer which can be suitably used for the heat-sensitive recording material. Disclosure of the invention

The present inventors have conducted intensive studies in order to achieve the first object, and as a result, found that a mixture of 4: 4′-dihydroxydiphenylenolesnorefone and 2,4′-dihydroxydiphenylsulfone as impurities was considered as an impurity. The mechanism (causal relationship) between the content of the phenol sulfonate phenyl ester contained therein and the degree of background capri generation in the heat-sensitive recording material using the mixture containing the impurities as a color developer Is not clear, but found a correlation. Then, based on the knowledge that was not known at all, it was found that the content of phenyl sulfonic acid phenyl ester was adjusted to a specific amount or less. The present invention has been completed by confirming that the heat-sensitive recording material using the coloring agent has particularly low background capri and excellent storage stability.

That is, in order to achieve the first object, the color developer of the present invention contains, as a main component, a mixture of 4,4′-dihydroxydiphenylsulfone and 2,4′dihydroxydiphenylsulfone. The weight ratio of the two compounds is in the range of 90:10 to 10:90, and the content of phenyl sulfonic acid phenyl ester relative to the mixture is 1.5% by weight or less. It is characterized by

Further, in order to achieve the first object, the color developer of the present invention may have a content of the phenyl sulfonic acid phenyl ester of 10% by weight or less in addition to the above configuration. More preferred. Furthermore, in order to achieve the first object, the developer of the present invention further comprises, in addition to the above-mentioned constitution, a weight ratio of (4: 4′dihydroxydiphenylenolesnorehon: 2,4′-dihydroxydib). More preferably, it is in the range of S 30: 70 to 80: 20.

According to the above arrangement, the developer is a phenol to a mixture of 4,4'-dihydroxydiphenylsulfone and 2,4'-dihydroxydiphenylsulfone mixed in a weight ratio within a specific range. The content of phenyl monosoluphonate is 1.5% by weight or less. This makes it possible to provide a developer which is particularly suitable for obtaining a heat-sensitive recording material having less background strength and excellent storage stability.

In order to achieve the first object, the dispersion of the present invention is characterized by dispersing the above-mentioned developer and a coloring dye in a dispersion medium. Therefore, especially heat sensitive recording with little background capri and excellent storage stability A dispersion containing a developer suitable for obtaining the material can be provided. In order to achieve the first object, the heat-sensitive recording material of the present invention is a heat-sensitive recording material having a heat-sensitive coloring layer containing a color developer and a color-forming dye on a support, wherein the color developer is , 4,4, dihydroxydiphenylsulfone and 2 _: 4, -dihydroxydiphenylsulfone as a main component. The weight ratio of the above two compounds is 90:10 to 10:10. 90, and the phenolsulfonic acid phenyl ester content relative to the mixture is not more than 1.5% by weight.

Further, in order to achieve the first object, the thermosensitive recording material of the present invention more preferably has the content of the phenyl sulfonic acid phenyl ester of 1.0% by weight or less in addition to the above configuration. Further, in order to solve the above-mentioned problems, the heat-sensitive recording material of the present invention preferably has the weight ratio in the range of 30:70 to 80:20 in addition to the above configuration. . According to the above arrangement, the developer is a phenol to a mixture of 4,4, dihydroxydiphenylenolesnorefone and 2,4, dihydroxydiphenylsulfone mixed in a weight ratio within a specific range. The content of phenyl sulfonate is 1.5% by weight or less. As a result, it is possible to provide a heat-sensitive recording material which has a small amount of background friction and has excellent storage stability.

In addition, as a result of diligent studies to achieve the second object, the present inventor has found that dissolution of a mixture of 4,4′-dihydroxydiphenylsnolephone and 2,4′-dihydroxydiphenylsulfone Although the mechanism (causal relationship) is not clear, there is a correlation between the Hazen value of the color and various performances of the color developer containing the above both compounds at a specific weight ratio and as a main component. That I found it. Based on the knowledge that was not known at all, the 4,4′-dihydroxydiphth is mixed at a weight ratio within a specific range, and the Hazen value of the dissolved color is within a specific range 內. A thermosensitive recording material using a color developer containing a mixture of enyl sulfone and 2,4, dihydroxydiphenyl sulfone as a main component has high color development sensitivity and excellent whiteness of the background. After confirming that the storage stability of the ground was excellent, the present invention was completed.

That is, in order to achieve the second object, the color developer of the present invention contains, as a main component, a mixture of 4,4, dihydroxydiphenylenolesnorefone and 2,4, dihydroxydiphthylnitrosulfone. Wherein the weight ratio of the two compounds is in the range of 90:10 to 10:90 and the Hazen value of the dissolved color of the mixture is less than 400. .

Further, in order to achieve the second object, the developer of the present invention may have the weight ratio in the range of 75:25 to 35:65 in addition to the above composition. More preferred.

According to the above arrangement, the color developer is mixed with the 4,4′-dihydroxy sidipheninolenoleshone, which is mixed at a weight ratio within a specific range, and whose dissolved color has a Hazen value within a specific range. , 4 'dihydroxydiphenylenolesnorefone as a main component. As a result, the color development sensitivity is high, the whiteness of the background is excellent, and the storage stability of the color development image is excellent, especially the heat and moisture resistance, water resistance, plasticizer resistance and heat resistance. A developer suitable for obtaining a heat-sensitive recording material can be provided.

In order to achieve the second object, the dispersion of the present invention is characterized in that the above-mentioned developer and a coloring dye are dispersed in a dispersion medium. So Therefore, it is possible to obtain a heat-sensitive recording material that has high color-forming sensitivity, excellent whiteness of the background, and excellent storage stability of the color-formed image and the background, particularly, moisture-heat resistance, water resistance, plasticizer resistance, and heat resistance. It is possible to provide a dispersion containing a color developer suitable for the above.

In order to achieve the second object, the heat-sensitive recording material of the present invention is a heat-sensitive recording material having a heat-sensitive color-developing layer containing a color developer and a color-forming dye on a support. , 4,4'-Dihydroxydiphenylsulfone and a mixture of 2: 4, -dihydroxydiphenylsulfone as main components. The weight ratio of the above two compounds is 90:10 to 10: 9. It is characterized by having a Hazen value of less than 400 for the dissolved color of the mixture.

According to the above configuration, the developer is mixed with the 4,4'-dihydroxy sidifuheninoles renalefon, which is mixed in a weight ratio within a specific range, and whose dissolved color has a Hazen value within a specific range. It contains a mixture with 2,4'-dihydroxydiphenylenolesnorefone as a main component. This provides a heat-sensitive recording material that has high color-forming sensitivity and excellent background whiteness, and has excellent storage stability of a color-formed image and the background, particularly, moisture-heat resistance, water resistance, plasticizer resistance, and heat resistance. be able to.

Still other objects, features, and advantages of the present invention will be sufficiently understood from the following description. Also, the advantages of the present invention will become apparent in the following description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows the phenol sulfonic acid phenol contained as an impurity in the color developer. BEST MODE FOR CARRYING OUT the content of glycol ester, a _t invention is a graph showing the relationship between color density background

[Embodiment 1]

The following will describe one embodiment of the present invention.

Heat-sensitive recording material according to the present invention has a thermosensitive coloring layer containing a color forming dye and the color developer on the support,該顕color agent, 4, 4 'Jihi Dorokishijifue two Rusuruhon "H_〇 one C ₆ H ₄ — S 0 ₂ — C ₆ H ₄ — OH (4, 4 '— bisphenol S) ”and 2, 4, Jizy-doxydifuenoresnorehon“ H 0-C ₆ H ₄ -S 0 ₂ -C ₆ H ₄ -OH (2,4,1-bisphenol S) "as the main component, and the above 4,4, dihydroxydiphenylenolesnorefone , The weight ratio to dihydroxydiphenylenolesnorefone is in the range of 90:10 to: 10: 90, more preferably in the range of 30:70 to 80:20, In addition, the content of phenyl sulfonic acid phenyl ester in the mixture is 1.5% by weight or less, more preferably 1.0% by weight or less.

Phenyl sulfonic acid phenyl ester “HO—C ₆ H ₄ —S〇 ₃ —C ₆ H ₅ ” is a compound of 4,4′dihydroxydiphenylsulfone and Z or 2,4, dihydroxydiphenylsulfone. It is a compound by-produced as an impurity during production. There are three types of isomers, ortho, meta and para, depending on the substitution position of the OH group.

The content of phenolsulfonic acid phenyl ester in the mixture can be measured, for example, using high performance liquid chromatography (HPLC). An example of the measurement method (analysis conditions) is shown below. Column: YMC-Pack ODS -A 3 1 2 (6.0 φ X 150 mm)

Mobile phase: 0. 0 5 Μ- ΚΗ ₂ Ro_〇 ₄ / § Se Toni preparative Lil = 5 0/5 0 flow amount:. 1 O ml Zm in.

Detector: U V 2 5 4 nm

Elution time: 4,4 'jihidroxyjifeninorereshonorehon = approximately 4 minutes

2, 4 'dihydroxydipheniglesulfone = approximately 4.

5 minutes

Phenoenoresolefonic acid feninole ester = Approx. 9 minutes From the chart obtained by the above measurement method, the difference between 4,4'-dihydroxy sidipheninolenosolephon and 2,4, It is possible to calculate the content (% by weight) of the phenolsulfonic acid phenyl ester in the mixture.

The mixture of 4,4, dihydroxydiphenylsulfone and 2,4,1-dihydroxydiphenylsulfone according to the present invention (hereinafter simply referred to as a mixture) is disclosed in Japanese Patent Publication No. 7-119195. As disclosed in Japanese Patent Application Laid-Open No. H10-252577, for example, the reaction of phenol with p-phenolsulfonic acid as a sulfonating agent and Z or 0-phenolsulfonic acid It can be produced at low cost by a dehydration reaction or a dehydration reaction between phenol and sulfuric acid as a sulfonating agent. The reaction conditions such as the reaction temperature and the reaction time may be appropriately set so as to complete the dehydration reaction, and are not particularly limited.

After performing the dehydration reaction, the mixture can be taken out by performing various operations such as crystallization, filtration, and drying. And for the resulting mixture. If necessary, various ordinary purification operations such as solvent (extraction) treatment, crystallization, filtration, decolorization, and recrystallization are performed as appropriate to obtain 4,4'-dihydroxydiphenyl-sulphone and 2,4, dihydrofuran. Droxydiphenylsulfone can be isolated respectively. Therefore, by appropriately adding these isolated compounds, the weight ratio of 4,4′-dihydroxydiphenylsulfone and 2,4′-dihydroxydiphenyl-sulnorefone can be set to an arbitrary value, that is, , 90: 10 to 10: 90, and more preferably 30: 70 to 80: 20. That is, in the category of the “mixture” in the present invention, in addition to the mixture extracted from the reaction solution by the above-described various operations, 4,4′-dihydroxydiphenylsnolephone or 2,4 ′ , A mixture obtained by adding dihydroxydiphenylenosulfone and adjusting the weight ratio thereof, and a mixture of isolated 4,4 ′ dihydroxydiphenylenolesnorefone and 2,4 ′ dihydroxydiphenylenosulfone And a mixture obtained by mixing Les / Lehon with the above weight ratio.

If a developer containing a mixture containing 4,4'-dihydroxydiphenylsulfone as a main component in a ratio exceeding the above range is used, the color sensitivity of the heat-sensitive recording material may be reduced and the color may be developed. The storage stability of the image may decrease. In addition, when a developer containing a mixture containing 4,4, -dihydroxydiphenylsulfone as a main component in a ratio less than the above range is used, the storage stability of the color image of the heat-sensitive recording material and the background of the color, especially However, the plasticizer resistance may decrease. Therefore, the above mixture can be adjusted so that the weight ratio of 4,4′-dihydroxydiphenyl ninoresnorefone to 2,4′-dihydroxydiphenylsnorrephone is in the range of 90:10 to 10:10. I just need.

Here, the phenolsulfonic acid ester of the mixture is included. The correlation between the weight (% by weight) and the degree of background capri generation of the heat-sensitive recording material using the mixture as a color developer will be described with reference to FIG. 1 (graph). The horizontal axis in the graph indicates the content (% by weight) of phenolsnolephonic acid phenol ester calculated by the above-described measurement method using HPLC, and the vertical axis indicates the results obtained by performing a dynamic color development test described later. Indicates the color density of the background measured (colorimetric). The lower the coloring density, the lower the degree of occurrence of background capri can be evaluated. Specifically, if the coloring density is 0.10 or lower, more preferably 0.08 or lower, the background capri is lower. It can be evaluated that the improvement has been made sufficiently.

As is clear from the graph, the content of phenyl sulfonic acid phenyl ester in the mixture was 1.5% by weight. /. If it is below, the color density of the background can be 0.12 or less, and if it is 1.0% by weight or less, the color density of the background can be 0.10 or less.

Therefore, including Yuryou of phenol sulfonic acid phenylalanine ester for mixture 1. 5wt ^_0/0 need only be prepared in the following. The content of the phenol sulfonate phenol ester can be determined in the production process of the mixture by a conventional method such as solvent (extraction) treatment, crystallization, filtration, decolorization, recrystallization, etc. It can be prepared by appropriately performing various purification operations. Therefore, the preparation method is not particularly limited. As a solvent that can be suitably used for the above-mentioned solvent (extraction) treatment, for example, a mixed solvent of 1,2-dichlorobenzene and phenol can be mentioned.

This makes it possible to provide a developer which is particularly suitable for obtaining a heat-sensitive recording material having a small background capri and excellent storage stability. That is, departure Suitable for obtaining a heat-sensitive recording material that has high color sensitivity, excellent whiteness of the background, and excellent color images and excellent storage stability (wet heat resistance, water resistance, plasticizer resistance and heat resistance). Coloring agents can be provided.

Then, a dispersion obtained by dispersing a color developer containing the above mixture as a main component and a color-forming dye in a dispersion medium is coated on a support and dried to form a heat-sensitive coloring layer. Can be formed. That is, a heat-sensitive recording material having a heat-sensitive coloring layer containing a color developer and a color-forming dye on a support can be produced.

Specific examples of the color-forming dye include, for example, 3- (N, N-Jetylamino) -1 6-methyl-7-anilinofluoran, 3- (N, N-di-n- Butylamino) — 6-methyl-7-anilinofluorane, 3- {N-ethyl-N- (isobutyl) amino)-1-6-methyl-7-anilinofino-leorane, 3- (N, N-dipentinorea 1) 6-methyl-1 7-anilino fluoran, 3- (N, N-di_n_butylamino) — 6-methyl-7- (o-chloroaniline) fluoran, 3-(N, N-di-n-butylamino)-7-(o-chloroaniline) fluoran, 3- (N-ethyl-N_ (p-tolyl) amino } — Fluoran dyes such as 6-methyl-7-anilinofluorane; 3,3 bis (p-dimethylaminophenol) _ 6-dimethylaminophthalide, 3 1- (p-dimethylaminophenyl) 1 3- (2-phenyl-3-indole) phthalide, 3- (p-dimethylaminophenyl) 1-3 ((1,2,3-dimethyl-3) —In-drill) phthalide, 3,3—Bis (9—ethyl-3—forced lupazolyl) 1—5—dimethylaminophthalide, 3,3—bis (2—Fenil 3-in Drill) Triarylmethane dyes such as 5-dimethylamisophthalide; 4, 4, Diphenylmethane dyes such as bis-dimethylaminobenzhydridobenzyl ether; thiazine dyes such as benzoyl leucomethylene blue (phenothiazine dyes); spiro dyes such as 3-methylspirodinaphtopirane (spirobilan dyes) Ratatom dyes; Leuco auramine dyes; Indolin dyes; Indigo dyes; and other leuco dyes, which are colorless or pale at room temperature and appear as acidic substances when heated. Any dye can be used as long as it can be colored by reacting with the agent, and is not particularly limited. One of these coloring dyes may be used alone, or two or more of them may be used.

In the present invention, the ratio of the mixture in the developer is particularly preferably 95% by weight or more. Specific examples of the components (compounds) other than the mixture in the color developer include, for example, p-octylphenol, p_t—butynolephenore, p—feninolephenole, p—hi Droxyacetophenone, α-naphthol, ρ-tert-octylcatechol, 2,2'-zihdroxybiphenone, 1,1bis (ρ—hydroxy-pheno-butane) butane 2,2—bis (4-hih Droxypheninole) pronone, 2,2—bis (3—methyl-4-hydroxyphenyl) propane, 2,2—bis (3,5-dimethyl_4—hydroxyphenyl) propane, 2,2—bis (3 , 5-dichloro 4- hydroxyphenyl) Pronon, bis (3-aryloxy-4-hydroxyphenyl) sulfone, bis (3, 4 dihydroxyphenyl) Hong, 1, 1-bis (4-hydroxyphenyle) cyclohexane, bis (4-hydroxyphenylethione) bis {2- (4-hydroxyphenythio) ethoxy} methane , 4-1 (4-1-isopropoxy benzenes snolehoninole) phenol, 4-dimethinole hydroxyphthalanoate, Bis (4-hydroxyphenyl) butyl acetate, p-benzyl benzoate, 3,5-di-phenols such as monobutyl salicylic acid; aromatic carboxylic acids such as benzoic acid, phthalic acid and salicylic acid; zinc salicylate Metal salts of aromatic carboxylic acids; and the like, but are not particularly limited as long as they are compounds that can react with the chromogenic dye when heated. One of these compounds may be used alone, or two or more of them may be used, if necessary.

The amount of the developer used for the color-forming dye may be set according to the type and combination of the color-forming dye and the color developer, and is not particularly limited. On the other hand, the content of the developer is preferably in the range of 0.5 to 6 parts by weight, and more preferably in the range of 1 to 2.5 parts by weight.

The dispersing medium is not particularly limited as long as it is a compound capable of dispersing the color developer and the color-forming dye, and is not particularly limited, but may be a so-called water-soluble binder such as polyvinyl alcohol, latex, and methyl cellulose. Is preferred.

The dispersion may further contain a sensitizer as needed. That is, the heat-sensitive coloring layer formed using the dispersion further includes a sensitizer as needed in order to further improve the color-forming sensitivity, as long as various properties desired for the heat-sensitive recording material are not impaired. You may go out. As the sensitizer, a compound having a melting point in the range of 50 to 150 ° C. is preferable. Specifically, for example, amide stearate, amide palmitate, Ammonium nitrate. Nitrogen-containing compounds such as stearic acid anilide; 4-hydroxybenzoic acid benzyl ester, 4-monobenzyloxybenzoic acid benzyl ester, 2-naphthoic acid fu-noreestenole, 2 — Benzinoles Estenole Naphthoate, 1 — E Droxy 2-phenyl estenolate naphthoate, dibenzinoester oxalate, dioxalate (4—methinolebenzinolestearenole), terephthalenolate dibenzinoleate ester, isophthalanolate n-butinolestainolate, Estenoleich compounds such as toluenes phenol enolenoestenole; 4—Penzinolebiphenyl, m-terphenyl, 1,2—bis (3,4—dimethylthiophenyl) ethane, 1,2—bis (2,4— Aromatic compounds such as dimethinolephene) ethane, 1,2—bis (2,4,5—trimethylphenyl) ethane; 2—pentinoleoxynaphthalene, 1,4 diethoxynaphthalene, 1,2— Diphenoxetane, 1,2—Diphenoxybenzene, 1,4 Diphenoxybenzene, 4— (4, -Methylphenoxy) B) Biphenyl, dipheninolenoleshon, 4-methinolesifeninoresnorehon, 4,4,1-diisopropoxydiphenylenolesnorehon, 4,4 'diphenoxy Ether compounds such as aethenole and 1,2-bis (phenoxymethyl) benzene and sulfur-containing compounds; 4-acetylbiphenyl; and the like, but are not particularly limited. One of these sensitizers may be used alone, or two or more of them may be used as necessary. The amount of the sensitizer used for the color developer and the color-forming dye is not particularly limited.

The dispersion further contains a white pigment such as calcium carbonate, if necessary, or a filler such as kaolin or clay, a dispersing aid, an antioxidant, a storage stabilizer, or an additive such as an antifoaming agent. You may go out. In other words, the heat-sensitive coloring layer formed using the dispersion may contain the above additives as needed to further improve various performances and handleability as long as the various performances desired for the heat-sensitive recording material are not impaired. Further, it may be included. For developer and coloring dye The amount of the additive used is not particularly limited.

Further, the heat-sensitive recording material according to the present invention may further have an undercoat layer such as a heat insulating layer and an overcoat layer such as a protective layer in addition to the heat-sensitive coloring layer, if necessary.

The dispersion according to the present invention can be obtained by dispersing a color developer containing a mixture as a main component, a coloring dye, and, if necessary, the sensitizer and the additive in a dispersion medium. Examples of the method for preparing the dispersion include a method in which a dispersion containing a color developer and a dispersion containing a coloring dye are separately prepared, and then both are mixed. Sensitizer ゃ The additive may be added to the dispersion containing the color developer, may be added to the dispersion containing the color-forming dye, may be added to both, or may be the developer. The dispersion containing the sensitizer and the additive may be prepared separately from the dispersion containing the dye and the dispersion containing the color-forming dye, and then mixed with each other. After the developer is added to the dispersion medium, the particle size of the developer is added to the dispersion liquid using a dispersing machine such as a pole mill, a sand mill, an attritor, a colloidal mill, and a sand gliding mill. Can be obtained by pulverizing (wet pulverization) and dispersing the particles to a particle size of 3 μm or less, more preferably 1.5 μm or less. A dispersion containing a color-forming dye and a dispersion containing a sensitizer and an additive can be obtained in the same manner. The concentration of the color developer or color-forming dye in the dispersion is not particularly limited, and the type of the color developer, color-forming dye, or dispersion medium, a combination thereof, or a method of applying the dispersion on a support, etc. In consideration of the above, an appropriate concentration may be set so as to obtain an optimum concentration. The specific method for preparing the dispersion is not particularly limited.

As the support, specifically, for example, paper such as high-quality paper or a polymer film And the like. Therefore, as thermal recording materials, thermal recording paper, that is, recording paper (output paper) of various devices typified by information communication devices such as a facsimile machine and information recording devices such as printers, POS (point-to-point) of _sa l _es) bar code label information management systems, various tickets, a method of drying the coated card, and the like (the dispersion onto the support, i.e., a method of forming a heat-sensitive coloring layer, particularly The method is not particularly limited, and various known methods can be employed, and the amount of the dispersion applied per unit area of the support is not particularly limited. It is possible to provide a heat-sensitive recording material having a small amount and excellent storage stability. That is, it has a high coloring sensitivity, an excellent whiteness of the background, and a feeling of excellent storage stability of the color image and the background. It is possible to provide a recording material.

As described above, the developer of the present embodiment contains, as a main component, a mixture of 4,4′-dihydroxydiphenyl / resnolephon and 2,4′-dihydroxydiphenylenolesnorefone, The weight ratio of the two compounds is in the range of 90:10 to 10:90, and the content of phenolsulfonic acid phenolic ester with respect to the mixture is 1.5% by weight or less. .

In addition, as described above, the developer of the present embodiment has a configuration in which the content of the phenyl sulfonic acid phenyl ester is 1.0% by weight or less, in addition to the above configuration, Is in the range of 30:70 to 80:20.

This makes it possible to provide a developer which is particularly suitable for obtaining a heat-sensitive recording material having a small background capri and excellent storage stability.

As described above, the dispersion of the present embodiment has a configuration in which the above-described developer and the coloring dye are dispersed in a dispersion medium. This makes it especially possible It is possible to provide a dispersion containing a color developer which is suitable for obtaining a heat-sensitive recording material having a small amount of heat and excellent storage stability.

As described above, the heat-sensitive recording material of the present embodiment is a heat-sensitive recording material having a heat-sensitive coloring layer containing a color developer and a color-forming dye on a support, wherein the developer is 4, 4 And a mixture of dihydroxydiphenylsulfone and 2,4′-dihydroxydiphenylsulfone as main components, and the weight ratio of the above both compounds is 90:10 to 10:90. And the content of phenolsulfonic acid phenyl ester to the above mixture is 1.5% by weight or less.

Further, as described above, the thermosensitive recording material of the present embodiment has a configuration in which the content of the phenyl sulfonic acid phenyl ester is 1.0% by weight or less, in addition to the above-described configuration, Is within the range of 30:70 to 80:20.

This makes it possible to provide a heat-sensitive recording material that has particularly little background capri and has excellent storage stability.

[Embodiment 2]

The following will describe another embodiment of the present invention. The heat-sensitive recording material according to the present embodiment has a heat-sensitive color-developing layer containing a color developer and a color-forming dye on a support, and the color developer includes 4,4′-dihydroxydipheninolenolesone, It contains a mixture of 4 'dihydroxydiphenylenolesulfone as the main component, and the weight ratio of the above 4,4,1-dihydroxydiphenylsulfone to 2,4'dihydroxydiphenylsulfone is 90: 10 to 10: 90, and the Hazen value of the dissolved color of the mixture is adjusted to less than 400. For the sake of convenience, the description of the same configuration as that of the first embodiment will be omitted.

The Hazen value of the dissolved color according to the present embodiment refers to the Hazen value of the dissolved color of the mixture, which is measured according to the color number test method described in JISK 4101. The measurement method (measurement conditions) is as follows. That is, first, acetone (special grade reagent) and water are mixed at a volume ratio of 80:20 to prepare an aqueous acetone solution. Next, 5 g of a mixture of 4,4′-dihydroxydiphenylsnorephone and 2,4′-dihydroxydiphenylenolesnorefone was weighed and placed in the colorimetric tube A. To dissolve the mixture and adjust to the marked line (50 ml). At this time, observe visually and confirm that there is no foreign matter in the colorimetric tube A. On the other hand, the acetone solution is put into the colorimetric tube B and used as blank. Next, the colorimetric tubes A and B are set in a Hazen measuring instrument, and the Hazen measurement value is measured by comparing with the Hazen standard colorimetric liquid (based on JIS K4101). The measured Hazen value is set as the Hazen value (10%) of the dissolved color.

The mixture of 4,4′-dihydroxydiphenylsulfone and 2,4′-dihydroxydiphenylsulfone (hereinafter simply referred to as a mixture) according to the present embodiment is described in the first embodiment. For example, dehydration reaction of phenol with p-phenolsulfonic acid and / or o-phenolsulfonic acid as a sulfonating agent, or dehydration of phenol with sulfuric acid as a sulfonating agent It can be produced at low cost by the reaction. The reaction conditions such as the reaction temperature and the reaction time may be appropriately set so as to complete the dehydration reaction, and are not particularly limited. After performing the dehydration reaction, the mixture can be taken out by performing various operations such as crystallization, filtration, and drying. By performing the above operation, a mixture containing 2,4′-dihydroxydiphenylsulfone at 50% by weight or less can be obtained.

Then, the obtained mixture is further subjected to ordinary various purification operations, such as crystallization, filtration, decolorization, and recrystallization, as necessary, so that the Hazen value of the dissolved color of the mixture can be arbitrarily determined. It can be adjusted to a value, that is, less than 400. In addition, by appropriately performing the above-mentioned various purification operations, it is possible to isolate 4,4, dihydroxydipheninolesulfone and 2,4,1-dihydroxyxidiphenyl sulfone, respectively, as necessary. . Therefore, by appropriately adding these isolated compounds, the weight ratio of 4,4′-hydroxydiphenylenolesolephone to 2,4, dihydroxydiphenylenolesulfone can be adjusted to an arbitrary value. , Ie, within the range of 90:10 to 10:90, and more preferably within the range of 75:25 to 35:65. That is, in the category of the “mixture” in the present invention, in addition to the mixture removed from the reaction solution by the various operations described above,

A mixture obtained by adding 4,4-hydroxydiphenylenolesnorefone or 2,4-dihydroxydiphenylsulfone to adjust the weight ratio thereof, and a mixture of isolated 4,4, dihydroxydiphenylsulfone And 2,4, dihydroxydiphenylsulfone in the above weight ratio.

If a developer containing as a main component a mixture in which the proportion of 4,4, dihydroxydiphenylsulfone exceeds the above range is used, the coloring sensitivity of the heat-sensitive recording material is remarkably reduced, and the storage of the coloring image is maintained. The stability is significantly reduced. In addition, when a developer containing a mixture containing 4,4,1-dihydroxydiphenylsulfone as a main component in a ratio of less than the above range is used, the storage stability of the color image and background of the heat-sensitive recording material, especially However, the plasticizer resistance is significantly reduced. Thus, the above mixture has a weight ratio of 4,4, dihydroxydiphenylsulfone to 2,4, -dihydroxydiphene-noresnorefone in the range of 90:10 to 10:90, Further, it is sufficient that the Hazen value of the dissolved color is adjusted to less than 400, and the production method and production conditions (reaction conditions) are not particularly limited. Thereby, a mixture suitable for the developer is obtained. The use of a developer containing a mixture having a Hazen value of 400 or more of the dissolved color significantly reduces the whiteness of the background of the heat-sensitive recording material and the storage stability of the background, especially the heat resistance of the background. It decreases significantly.

Further, the color developer according to the present invention only needs to contain the above-mentioned mixture as a main component, and the preparation method thereof is not particularly limited. As a result, a heat-sensitive recording material having high color-forming sensitivity and excellent whiteness of the background, as well as excellent storage stability of a color-formed image and the background, in particular, moisture-heat resistance, water resistance, plasticizer resistance, and heat resistance. A developer which is suitable to obtain is obtained.

Then, a thermosensitive coloring layer is formed by applying a dispersion obtained by dispersing a developer containing the above mixture as a main component and a coloring dye in a dispersion medium on a support and drying the dispersion. can do. That is, a heat-sensitive recording material having a heat-sensitive coloring layer containing a color developer and a color-forming dye on a support can be produced.

The method for producing the above-mentioned heat-sensitive recording material is the same as in the first embodiment, and a detailed description is omitted.

As a result, color development sensitivity is high, the whiteness of the background is excellent, and A heat-sensitive recording material having excellent storage stability of an image and a background can be provided.

As described above, the developer of the present embodiment contains, as a main component, a mixture of 4,4,1-dihydroxydiphenylenolesnorefone and 2,4, dihydroxydiphenylenolesnorefone. , the weight ratio of the both compounds 9 0: 1 0-1 _0: 9 0 in the range of, and is a configuration Hazen value of dissolution color of the mixture is less than 4 ◦ 0.

Further, as described above, the developer of the present embodiment has a configuration in which the weight ratio is in the range of 75:25 to 35:65 in addition to the above configuration.

As a result, the color sensitivity is high, the whiteness of the background is excellent, and the storage stability of the color image is excellent, especially the heat-sensitive recording with excellent heat and moisture resistance, water resistance, plasticizer resistance and heat resistance. A developer suitable for obtaining the material can be provided.

As described above, the dispersion of the present embodiment has a configuration in which the above-described developer and the chromogenic dye are dispersed in a dispersion medium. This makes it possible to obtain a heat-sensitive recording material that has high color-forming sensitivity, excellent whiteness of the background, and excellent storage stability of the color-formed image and the background, in particular, moisture-heat resistance, water resistance, plasticizer resistance, and heat resistance. A dispersion containing a developer suitable for the above can be provided. As described above, the heat-sensitive recording material of the present embodiment is a heat-sensitive recording material having a heat-sensitive coloring layer containing a color developer and a color-forming dye on a support, wherein the developer is 4, 4 A mixture of 2,4, dihydroxydiphenylsulfone and 2,4, dihydroxydiphenylsulfone as a main component, wherein the weight ratio of the above both compounds is 90:10 to 10:90. It is within the range, and the Hazen value of the dissolved color of the mixture is less than 400. As a result, a heat-sensitive recording material having high color sensitivity and excellent whiteness of the background and excellent storage stability of the color image and the background, particularly excellent in moisture-heat resistance, water resistance, plasticizer resistance and heat resistance. Can be provided.

【Example】

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Color development of heat-sensitive recording paper The sensitivity and storage stability were evaluated by a dynamic color development test, a heat and humidity resistance test, a plasticizer resistance test and a heat resistance test of the color image and the background.

(Dynamic color development test)

Using a printing tester (manufactured by Oshoku Denki Co., Ltd.), a dynamic coloring test was performed under the conditions of 24 V and 1.0 Oms, and a coloring image (printed portion) was formed on the thermal recording paper. Then, using a Macbeth reflection densitometer (RD-914), the color image on the thermosensitive recording paper and the color density of the background were measured (colorimetry).

The thermal recording paper can be evaluated as having a higher color development sensitivity as the color density of the color image becomes higher, and as having a lower whiteness of the background as the color density of the background becomes lower.

(Moisture and heat resistance test)

The heat-sensitive recording paper after the dynamic color development test was kept in a thermo-hygrostat at 50 ° C. and a relative humidity of 90% for 24 hours. Thereafter, using a Macbeth reflection densitometer (RD-914), the color density of the color image on the thermal recording paper was measured.

The smaller the change in the color density before and after the test, the better the heat-sensitive recording paper is.

(Plasticizer resistance test) A film (wrap) made of polyvinyl chloride was adhered to the entire surface of the heat-sensitive recording paper after the dynamic color test. Next, the heat-sensitive recording paper was kept in a dryer at 40 ° C. for 24 hours. Thereafter, using a Macbeth reflection densitometer (RD-914), the color density of the color image on the thermal recording paper and the background color was measured.

The smaller the change in the coloring density before and after the test, the better the plasticizer resistance of the thermal recording paper can be evaluated.

(Heat resistance test)

The heat-sensitive recording paper after the dynamic color development test was kept in a thermostat dryer at 80 ° C for 24 hours. Thereafter, the color image of the thermosensitive recording paper and the color density of the background were measured using a Macbeth reflection densitometer (RD-914).

The smaller the change in the coloring density before and after the test, the better the heat resistance of the thermal recording paper can be evaluated.

Therefore, the higher the evaluation in each of the above tests and the better the balance, the more the heat-sensitive recording paper can be evaluated to be excellent in color sensitivity and storage stability. Examples 1 to 3 and Comparative Examples 1 and 2 described below contain a mixture of 4,4′-dihydroxydiphenylenolesnorefone and 2,4′-dihydroxydiphenylsulfone as main components. The weight ratio of the two compounds is in the range of 90:10 to 10:90, and the content of phenyl sulfonic acid phenyl ester in the mixture is 1.5% by weight or less. Examples and comparative examples of a color developer and a thermosensitive recording material containing the color developer, that is, Examples and Comparative Examples for Embodiment 1.

Further, Examples 4 to 6 and Comparative Examples 3 to 5 show the comparison between 4,4, dihydroxydiphene / les / lejon and 2,4,1-dihydroxydiphenineresolene. A mixture as a main component, the weight ratio of the two compounds is in the range of 90:10 to 10:90, and the Hazen value of the dissolved color of the mixture is less than 400. Examples and comparative examples of a developer and a heat-sensitive recording material containing the developer, that is, examples and comparative examples for the second embodiment.

(Example 1)

First, a mixture of 4,4′-dihydroxydiphenylsulfone and 2,4′-dihydroxydiphenylsulfone was prepared by the following method <that is, 1,2-dichlorobenzene (328 g, theoretical 1 volume times the amount of the mixture) and 207 g (2.2 mol) of phenol were charged into a reactor, and 100 g of 98% sulfuric acid (1 mol) was stirred while stirring the contents. Was dropped, and the temperature was raised after the completion of the dropping. Then, the reaction proceeded and the contents boiled at around 150 ° C, and water (reaction water) began to distill together with 1,2-dichlorobenzene.The distillate was condensed by the condenser and trapped. After separating into two phases with, the lower phase, 1,2-dichlorobenzene phase, was continuously returned to the reactor (within the reaction system). Five hours after the start of distillation, the temperature of the reactants (contents) reached 180 ° C, and water generation stopped. The amount of upper phase (aqueous phase) separated by the trap is 38 m

Was one. After water generation stopped, the reaction was continued for another hour.

The obtained reaction product was analyzed by HPLC, and as a result, 4,4'-dihydroxymethyldiphenylenolesnorefone: 2,4, dihydroxydiphenylenolesnolephone: trihydroxy-trif- Rudisulfone (impurity) is 6 by weight

9: 2 9: 2. Thereafter, the reaction product was cooled to 25 ° C., and the precipitated crystals were separated by filtration, washed, and dried. Next, 700 g of water and 20 g of sodium hydroxide were added to the obtained crystals, dissolved by heating, and treated with activated carbon. 45 g of 50% sulfuric acid was added and the mixture was cooled. Then, the precipitated crystals were separated by filtration, washed and dried. As a result, 210 g of crystals (mixture of isomers) was obtained. The crystals were analyzed by HPLC. As a result, 4,4′-dihydroxydiphenylsnolephone: 2,4′-dihydroxydiphenyl- / less / lephon: trihydroxydiphenyldisulfone: 70: 3 by weight ratio of trihydroxydiphenyldisulfone. 0: 0 ₍ As a result of analysis using HPLC, the content of phenyl sulfonic acid phenyl ester in the mixture was 0.03% by weight ⁰ /.) The mixture was used as a developer. Used.

First, 20 g of 3- (N, N-di-n-butylamino) -6-methyl-7-anilinofluoran (color-forming dye) was mixed with 100 g of a 10% by weight aqueous solution of polybutyl alcohol, A dispersion a having an average particle diameter of 0.8 μm was prepared by dispersing while pulverizing using a ball mill.

On the other hand, 20 g of the above mixture and 100 g of a 10% by weight aqueous solution of polyvinyl alcohol are mixed and dispersed while being ground using a ball mill, whereby a dispersion having an average particle diameter of 0.8 m is obtained. b was prepared.

Also, by mixing 20 g of acetylacetylbiphenyl (sensitizer) and 100 g of a 10% by weight aqueous solution of polyvinyl alcohol, and dispersing the mixture while pulverizing using a pole mill, the average particle diameter is reduced. Was 0.8 m.

Then, after mixing the above dispersions a to c at a weight ratio of 1: 2: 2 to prepare 200 g of a mixture, 50 g of calcium carbonate (white pigment) was added to the mixture. By dispersing, a dispersion liquid for forming a thermosensitive coloring layer was prepared. This dispersion was applied to a high-quality paper (support) so that the coating amount after drying was 6 g Zm ^2, and dried to form a thermosensitive coloring layer on the high-quality paper. That is, a heat-sensitive recording paper (heat-sensitive recording material) according to the present invention was obtained. The above test was performed using the obtained thermal recording paper. The results are shown in Table 1. The heat-sensitive recording paper had high coloring sensitivity, excellent whiteness of the background, and excellent storage stability of the colored image.

(Example 2)

By adding phenyl sulfonic acid phenyl ester to the crystals obtained in Example 1, the content of phenyl sulfonic acid phenyl ester relative to the mixture was adjusted to 0.3% by weight. Then, the same operation as in Example 1 was performed except that this mixture was used as a developer, to obtain a thermosensitive recording paper, and the above-described test was performed. Table 1 shows the results.

(Example 3)

By adding phenyl sulfonic acid phenyl ester to the crystals obtained in Example 1, the content of phenyl sulfonic acid phenyl ester relative to the mixture was adjusted to 0.9% by weight. Then, the same operation as in Example 1 was carried out except that this mixture was used as a color developer, thereby obtaining a thermosensitive recording paper and performing the above-mentioned test. Table 1 shows the results.

(Comparative Example 1)

First, the same reaction as in Example 1 was performed to obtain a reaction product. The obtained reaction product was analyzed by HPLC, and as a result, 4,4, dihydroxydiphenylsnolephone: 2,4 ′ dihydroxydiphenyleninoreslephone: The ratio was 69: 29: 2. Thereafter, 1,2-dichlorobenzene and the like are distilled off with 120. The reaction was dried. The obtained solid was analyzed by HPLC, and as a result, 4,4'-dihydroxydiphenylenolesnorefone: 2,4, -dihydroxydiphenyldisulfonic acid: trihydroxydiphenyldisulfonic acid was converted to a 69: 2 by weight ratio. 9: 2.

Next, 700 g of water and 20 g of sodium hydroxide were added to the obtained solid to dissolve by heating, treated with activated carbon, and then cooled by adding 45 g of 50% sulfuric acid. The precipitated crystals were separated by filtration, washed and dried. As a result, 210 g of crystals (mixture of isomers) was obtained. The crystals were analyzed by HPLC, and as a result, 4,4'-dihydroxydifeninoresnorrenone: 2,4'-dihydroxydifenienolesnorrenone: trihydroxydiffenienoresnorenophone Was 70: 30: 0 by weight.

In addition, the content of phenolsulfonic acid ester based on the mixture was 2.5% by weight. Then, by performing the same operation as in Example 1 except that this mixture was used as a color developer, a thermosensitive recording paper for comparison was obtained, and the above test was performed. Table 1 shows the results. The heat-sensitive recording paper was inferior in the whiteness of the background because the content of phenolsulfonic acid polyester was out of the preferred range.

(Comparative Example 2)

By adding phenolsulfonic acid phenol ester to the crystals obtained in Comparative Example 1, the content of phenolsulfonic acid phenylester in the mixture was adjusted to 8.0% by weight. Then, the same operation as in Example 1 was performed except that this mixture was used as a color developer, to obtain a thermosensitive recording paper for comparison, and the above test was performed. The results are shown in Table 1. The thermal recording paper had a good phenolsulfonic acid phenyl ester content. Because it was out of the proper range, the whiteness of the ground was poor

Abbreviations in the table are as follows

4,4, body: 4,4'-dihydroxydifenienoresnorehon

2,4, body: 2,4 'dihydroxydifeninoles / lejon

I-Dani (1): Phenols / Pheninolenate Lefonic Acid

(Example 4)

The 4,4-,-dihydroxydiphenylenosulfone and the 4,4, -dihydroxydiphenylsulfone which have a Hazen value of 100 of the dissolved color of the mixture when mixed at a weight ratio of 75:25. Was used as a developer.

First, 20 g of 3- (N, N-di-n-butylamino) -16-methyl-7-anilinofluoran (color-forming dye) and 100 g of a 10% by weight aqueous solution of polyvinyl alcohol were added. By mixing and dispersing while pulverizing using a ball mill, a dispersion _a having an average particle diameter of 0.8 m was prepared.

—, 4, 4 '—Dihydroxydiphenylenolesnorephone (20 g) is mixed with 100% by weight of a 10% by weight aqueous solution of polyvinyl alcohol, and a ball mill is used. Then, the mixture was dispersed while pulverizing to prepare a dispersion b having an average particle diameter of 0.8 m.

Furthermore, a mixture of 20 g of 2,4′-dihydroxydiphenylsulfone and 100 g of a 10% by weight aqueous solution of polybutyl alcohol was dispersed by pulverizing using a ball mill to obtain an average particle size. A dispersion c having a diameter of 0 was prepared.

Further, 20 g of 4-acetylbiphenyl (sensitizer) and 100 g of a 10% by weight aqueous solution of polyvinyl alcohol are mixed, and dispersed while being pulverized using a ball mill to obtain an average particle diameter. Was 0.8111.

Then, 200 g of a mixture was prepared by mixing the above dispersions a to d at a weight ratio of 5: 7.5: 2.5: 10, and the mixture was added to calcium carbonate (white pigment). A dispersion for forming a thermosensitive coloring layer was prepared by adding and dispersing 50 g. Therefore, the weight ratio of 4,4′-dihydroxydiphenylenolesnorefone to 2,4, dihydroxydiphenylsulfone in the above dispersion is 75:25.

This dispersion was applied to a high-quality paper (support) so that the coating amount after drying was 6 g Zm ^2, and dried to form a thermosensitive coloring layer on the high-quality paper. That is, a heat-sensitive recording paper (heat-sensitive recording material) according to the present invention was obtained. Each of the above tests was performed using the obtained heat-sensitive recording paper. Table 2 shows the results. The heat-sensitive recording paper had high coloring sensitivity, was excellent in the whiteness of the background, and was excellent in the storage stability of the colored image and the background.

(Example 5)

The Hazen value of the dissolved color of the mixture when mixed at a weight ratio of 35:65 is 2 4,4, dihydroxydiphenylenolesnorefone, which is 0, and 2,4'dihydroxydiphenylsulfone were used as developers.

Then, except that the dispersions a to d were mixed in a weight ratio of 5: 3.5: 6.5: 10, the same operation as in Example 4 was performed to obtain a thermosensitive recording paper. . Thus, the weight ratio of 4,4, dihydroxydiphenylsulfone to 2,4'-dihydroxydiphenyls / lefon in the dispersion is 35:65.

Each of the above tests was performed using the obtained heat-sensitive recording paper. Table 2 shows the results. The heat-sensitive recording paper had high coloring sensitivity, was excellent in the whiteness of the background, and was excellent in the storage stability of the colored image and the background.

(Example 6)

The dissolution color of the mixture when mixed at a weight ratio of 35:65 has a Hazen value of 300,4,4, dihydroxydiphenylenolesnolephone and 2,4'-dihydroxydiphenylsulfone. Was used as a developer.

A thermosensitive recording paper was obtained by performing the same operation as in Example 4 except that the dispersions a to d were mixed at a weight ratio of 5: 3.5: 6.5: 10. . Therefore, the weight ratio of 4,4, dihydroxydiphenylsulfone to 2,4, dihydroxydiphenylsulfone in the dispersion is 35:65.

Each of the above tests was performed using the obtained heat-sensitive recording paper. Table 2 shows the results. The heat-sensitive recording paper had high color-forming sensitivity, excellent whiteness of the background, and excellent storage stability of the color-formed image and the background.

(Comparative Example 3)

The Hazen value of the dissolved color of the mixture when mixed at a weight ratio of 35:65 is 5 0,4,4,1-dihydroxydiphenylsulfone and 2,4, dihydroxydiphenylsulfone were used as developers.

A comparative thermosensitive recording paper was obtained by performing the same operation as in Example 4 except that the dispersions a to d were mixed at a weight ratio of 5: 3.5: 6.5: 10. Was. Therefore, the weight ratio of 4,4, dihydroxydiphenylsnolephone to 2,4'-dihydroxydiphenylinolesulfone in the dispersion is 35:65.

Each of the above tests was performed using the obtained heat-sensitive recording paper for comparison. Table 2 shows the results. Since the heat-sensitive recording paper had a Hazen value of the dissolved color of the mixture of 400 or more, the whiteness of the background was poor and the storage stability of the background, particularly the heat resistance of the background was poor.

(Comparative Example 4)

4,4,1-Dihydroxydiphenyl sulfone, which has a Hazen value of 50 for the dissolved color, was used as the developer. In other words, 2,4, dihydroxydipheninolenolesone was not used.

Then, the same operation as in Example 4 was performed except that the dispersions a, b, and d were mixed at a weight ratio of 5:10:10 to obtain a thermosensitive recording paper for comparison.

Each of the above tests was performed using the obtained heat-sensitive recording paper for comparison. Table 2 shows the results. Since the thermal recording paper does not use a mixture of 4,4, dihydroxydiphenylsulfone and 2,4,1-dihydroxydiphenylsulfone, the recording sensitivity is remarkably inferior and the storage stability of the color image is low. The sex was remarkably inferior.

(Comparative Example 5) 2,4,1-dihydroxydiphenyl sulfone with a dissolved color Hazen value of 50 was used as a developer. That is, 4,4, dihydroxydiphenylsulfone was not used.

Then, the same operation as in Example 4 was performed except that the dispersions a, c, and d were mixed at a weight ratio of 5:10:10 to obtain a thermosensitive recording paper for comparison.

Each of the above tests was performed using the obtained heat-sensitive recording paper for comparison. Table 2 shows the results. Since the heat-sensitive recording paper did not use a mixture of 4,4, -dihydroxydiphenylsulfone and 2,4'-dihydroxydiphenylsulfone, the storage stability of the color image was remarkably inferior.

(Example 7)

By adding phenyl sulfonic acid phenyl ester to the crystals obtained in Example 1, the content of phenyl sulfonic acid phenyl ester relative to the mixture was adjusted to 0.1% by weight. The Hazen value of this mixture was 50. And the crystals 2 0 g of polyvinyl alcohol 1 0 wt ^_0/0 aqueous solution 1 0 0 g were mixed, Ri by the fact of dispersing while pulverizing with a ball mill, the average particle diameter is 0. 8 mu m Dispersion b was prepared.

Then, the same operation as in Example 4 was performed except that the dispersions a, b, and d were mixed at a weight ratio of 5:10:10, to thereby obtain a thermosensitive recording paper.

Each test was conducted in the first half of the period using the obtained thermal recording paper. Table 2 shows the results. The heat-sensitive recording paper had high color-forming sensitivity, excellent whiteness of the background, and excellent storage stability of the color-formed image and the background.

Table 2 Moisture and heat resistance test

Background coloring image Background coloring image

4 0 .0 8 0 .9 7 0 .1 0 .0 .7 0

Application 50.09.90.70.90.7.2 Example: 6.0.10.0.96.0.120.7.1

7 0 .0 8 0 .9 5 0 .0 9 0 .7 2

Ratio 30.0.0.950.210.68 Comparison 40.10.0.0.70.10.0.35 Example 50.0.09.0.970.0.90 . 4 0

Plasticizer resistance test Heat resistance test

Background coloring image Background coloring image

4 0 .0 8 0 .9 0 0 .1 0 .9 1

50.09.085.0110.8.8 8.Example 60.12.0.850.13.0.88

7 0 .0 8 0 .8 7 0 .1 1 0 .8 9

Ratio 30.20.80.90.81 1 Comparison 40.100.0.470.100.40 Example 50.90.0.260.10. 5 4 Note that the specific embodiments or examples made in the section of the best mode for carrying out the invention clarify the technical contents of the present invention, and The present invention should not be construed as being limited to only the above, but can be implemented with various modifications within the spirit of the present invention and the scope of the claims described below.

INDUSTRIAL APPLICABILITY The present invention can be used for a color developer and a heat-sensitive recording material.

Claims

The scope of the claims

It contains a mixture of 1.4,4 'dihydroxydiphenylenolesnorefone and 2,4'dihydroxydiphenylsulfone as the main component, and the weight ratio of the above both compounds is 90: 10 to 10: within the range of 90, and

A developer having a phenolsulfonic acid phenyl ester content of 1.5% by weight or less relative to the mixture, and / or a Hazen value of a dissolved color of the mixture of less than 400. .

2. The developer according to claim 1, wherein the content of the phenyl sulfonic acid phenyl ester is 1.0% by weight or less.

3. The developer according to claim 1, wherein the weight ratio is in the range of 30:70 to 80:20.

4. The developer according to claim 3, wherein the weight ratio is in the range of 75:25 to 35:65.

5. A dispersion obtained by dispersing the developer according to any one of claims 1 to 4 and a chromogenic dye in a dispersion medium.

6. A thermosensitive recording material having a thermosensitive coloring layer containing a developer and a coloring dye on a support, wherein the developer is 4,4 'dihydroxydiphenyl sulfone and 2,4, jigh. A mixture with hydroxydiphenyl sulfone as a main component, wherein the weight ratio of the two compounds is in the range of 90:10 to 10:90, and

A heat-sensitive recording material characterized in that the content of phenol sulfonic acid fuunyl ester with respect to the mixture is not more than 1.5% by weight, and the Z or the Hazen value of the dissolved color of the mixture is less than 400. .

7. The heat-sensitive recording material according to claim 6, wherein the content of the phenyl sulfonic acid phenyl ester is 1.0% by weight or less.

8. The heat-sensitive recording material according to claim 6, wherein the weight ratio is in the range of 30:70 to 80:20.