JPH0976632A - Recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording material with coloring speed enhanced in particular in a low temperature environment in the event of coloring caused by contact between an electron accepting developer and electron donating coupler. SOLUTION: The recording material includes a microcupsle having an electron donating coupler dissolved in a solvent and an electron accepting developer, and the electron accepting developer is of an organic developer, and the solvent of the coupler can dissolve the organic developer, yet an organic liquid is made having a viscosity of 200cps or lower of a 35wt.% solution of the organic developer at 25 deg.C and a boiling point of 175 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-shaped recording material having a high coloring speed, and more particularly to a pressure-sensitive recording material.

[0002]

2. Description of the Related Art Microcapsules containing an electron-donating color former (hereinafter sometimes referred to as "color former") dissolved in a solvent and an electron-accepting developer (hereinafter referred to as "color former") The recording material utilizing the fact that a color-developed image is formed by the reaction between a color-developing agent and a color-developing agent has been known for a long time and is widely used.

Such recording materials are roughly classified into pressure sensitive recording materials and heat sensitive recording materials. The pressure-sensitive recording material is one in which a microcapsule containing a color-developing agent is destroyed by applying a pressure to this to form a color-developed image by reacting the color-developing agent with the color-developing agent. Coloring agent layer comprising microcapsules containing (hereinafter, "coloring agent layer"
And a developer layer containing a developer (hereinafter,
And a "color developer layer") are formed on the surfaces of separate supports or different surfaces of the same support, and the carbon-free paper is used by bringing the color developer layer and the developer layer into contact with each other. Type recording material, a so-called self-coloring type pressure-sensitive recording material (or press-type paper, self-developing) provided with a self-coloring layer containing a microcapsule containing a color-forming agent and a developer on the same surface of a support. There is something called a "contained paper".

In a carbonless paper type recording material, a color former layer is formed on one side of a support (generally paper) to form an upper sheet, and a color former layer is formed on one side of the support and on the opposite side. It is used by forming a developer layer to form a middle paper, forming a developer layer on one side of a support to form a lower paper, and contacting the color developer layer with the developer layer.

In addition, in the self-coloring type pressure-sensitive recording material, when pressure is applied to the surface on which the self-coloring layer is provided, the microcapsules are destroyed and the color-developing agent reacts with the color-developing agent to develop a color on the self-coloring layer. Since an image is formed, plain paper is placed on the self-coloring layer of the self-coloring type pressure-sensitive recording material, and an image such as letters is recorded on the plain paper with a writing instrument, type, etc. When forming a color image on the color-developing layer, OCR printing is performed when a color-developed image is formed by printing directly on the self-color-developing layer of the self-color-developing pressure-sensitive recording material without using an ink ribbon. It is used in some cases. Furthermore, when making multiple copies, a self-coloring type pressure-sensitive recording material in which a self-coloring layer is provided on one side of the support and a color-developing layer is formed on the opposite side is used to form a color on one side of the support. It may be used in combination with a medium sheet having a developer layer and a developer layer on the opposite side thereof or a lower sheet having a developer layer on one surface of a support. The self-coloring layer of the self-coloring type pressure-sensitive recording material may be a two-layer type in which a colorant layer containing microcapsules containing a colorant and a developer layer containing a developer are laminated, There is a single-layer type including a color developer and a microcapsule containing a color developer.

On the other hand, a heat-sensitive recording material containing such microcapsules is disclosed in, for example, JP-A-63-2656.
No. 82 and JP-A-1-105782, there is a heat-sensitive recording material in which a heat-sensitive layer containing microcapsules containing a color former and a color developer is formed on a support. The heat-sensitive recording material containing the microcapsules is
It has the advantage that it can be designed for HP and can be designed as a multicolor thermal recording material.

The microcapsules contained in the recording material as described above contain a color former dissolved in a solvent. As the solvent, a substance capable of dissolving the used color former is used, and generally naphthene oil, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylalkane, phthalic acid ester, etc. are used. There is. Such a solvent generally takes into consideration the type of color former used in the microcapsules so that a high color density can be obtained.
The material of the capsule wall, and the combination with the material of the color developer are also used in consideration. Further, although some of the above-mentioned solvents have a bad or unpleasant odor, it is a matter of course that a solvent having no bad odor is preferable.

[0008]

However, when the color is developed using the microcapsules in which the solution of the color former is dissolved in the solvent and the color developer, the color development speed is still sufficiently high. However, the color development rate is not particularly high at low temperatures, and an improvement in color development rate is desired. It is an object of the present invention to provide a recording material having an improved color development speed when a color is developed by contact between an electron accepting color developing agent and an electron donating color developing agent. Another object of the present invention is to provide a recording material in which the color development rate at the time of color development by contact between an electron-accepting color developing agent and an electron-donating color developing agent is improved especially in a low temperature environment.

[0009]

The object of the present invention is to provide a recording material containing microcapsules containing an electron-donating color former dissolved in a solvent and an electron-accepting developer.
The electron-accepting developer is an organic developer, and the solvent of the color former is capable of dissolving the organic developer,
Further, it can be achieved by a recording material characterized by being an organic liquid having a boiling point of 175 ° C. or higher, which shows a viscosity of a 35% by weight solution of the organic developer at 25 ° C. at 200 ° C. or lower.

The preferred embodiments of the present invention are as follows. 1) The organic liquid has the following general formula:

[0011]

Embedded image

[However, R ¹ , R ² , R ³ , R ⁴ and R ⁵
Each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ¹ , R ² , R ³ , R ⁴ and R
^At least 4 of ⁵ represents an alkyl group. ] At least one compound represented by
Weight% or more). 2) The organic liquid is 1,2,4,5-tetramethylbenzene, 1,2,3,5-tetramethylbenzene, 1,
2,3,4-tetramethylbenzene and 1,2,3
Contain at least one compound selected from the group consisting of 4,5-pentamethylbenzene (preferably 10% by weight)
that's all). 3) The organic developer is at least one kind of metal salt of aromatic carboxylic acid and phenol formaldehyde resin (preferably metal salt of aromatic carboxylic acid). 4) The electron-donating color former contains at least one selected from the group consisting of crystal violet lactone, benzoyl leuco methylene blue, fluorane compounds, indolyl phthalide compounds and indolyl azaphthalide compounds. 5) The recording material, wherein the walls of the microcapsules are polyurethane urea. 6) The above recording material which is a pressure sensitive recording material.

The form of the recording material of the present invention is not particularly limited as long as it contains the above-mentioned electron-donating color former and developer. That is, the recording material of the present invention is a carbonless paper-type pressure-sensitive recording material in which the color former layer and the developer layer are formed on the surface of a separate support or another surface of the support, as described above. A self-coloring type pressure-sensitive recording material provided with a self-coloring layer containing a microcapsule containing a color former and a color developer on the same surface of the body, and a microcapsule containing a color former and a color developer The heat-sensitive layer may be in any form of a heat-sensitive recording material formed on a support. As described above, in the recording material of the present invention, the solvent that dissolves the color former contained in the microcapsules contains an organic liquid having a boiling point of 175 ° C. or higher, which shows a low viscosity when the organic developer is dissolved. It is characterized by being able to go out. Hereinafter, mainly the carbonless paper type pressure-sensitive recording material will be described in detail. It will be easily understood by those skilled in the art that similar effects can be obtained with other types of recording materials.

In the present invention, the solvent used for dissolving the color former is capable of dissolving the organic developer and has a viscosity at 25 ° C. of a 35% by weight solution of the organic developer. It is an organic liquid having a boiling point of 175 ° C. or higher, which indicates 200 cps or lower. That is, the solvent of the present invention may be composed of only an organic liquid having the above-mentioned viscosity at a boiling point of 175 ° C. or a mixture thereof, and as long as it has such a property, the organic liquid and another organic solvent may be mixed. It may be a mixture.
The solvent (organic liquid) of the present invention has the following general formula:

[0015]

Embedded image

[However, R ¹ , R ² , R ³ , R ⁴ and R ⁵
Each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ¹ , R ² , R ³ , R ⁴ and R
^At least 4 of ⁵ represents an alkyl group. ] It is preferable that at least one compound represented by
That is, the compound of the above general formula having a boiling point of 175 ° C. or higher can be used as it is, but the compound of the above general formula which is not liquid at room temperature is mixed with the compound which is the above liquid to obtain the above-mentioned characteristics. Is used. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and t.
-Butyl is common, methyl and ethyl are preferred, and methyl is especially preferred. Examples of solvents that can be used alone in the solvent of the present invention include 1,2,3,5-tetramethylbenzene (boiling point 195 ° C., melting point −24.1 ° C.) and 1,2,3,4-tetramethylbenzene. (Boiling point 203
C., melting point −6.4 ° C.), and non-liquid compounds that can be used in combination therewith are 1,2,4,5-tetramethylbenzene (boiling point 191 ° C., melting point 80 ° C.) and 1,2,3 , 4,5-pentamethylbenzene (boiling point 23
1 ° C., melting point 53 ° C.). For example, as a preferable example of a commercially available product of the above solvent (organic liquid), Sur which is a mixture of the above isomers of tetramethylbenzene is used.
e Sol-150 (manufactured by Koch Chemical Company, boiling point 180 ° C.) can be mentioned.

Other organic solvents that can be used in the solvent (organic liquid) of the present invention include kerosene, vegetable oil, paraffin, naphthene oil, alkylated biphenyl (eg, monoisopropyl biphenyl), alkylated terphenyl. , Chlorinated paraffins, alkylated naphthalenes (eg diisopropylnaphthalene), diarylalkanes (eg,
1-phenyl-1-xylylethane) and phthalic acid ester. Alkylated biphenyl,
Alkylated naphthalenes and diarylalkanes are preferred, especially alkylated naphthalenes.

The boiling point of the solvent of the present invention has a lower limit of 178.
C. is preferable, and the upper limit is generally 300.degree. Further, the solvent of the present invention preferably contains 10% by weight or more, and particularly preferably 15% by weight or more of the solvent of the above general formula. The viscosity at 25 ° C. when the organic developer is dissolved into a 35 wt% solution is preferably 10 to 200 cps, and particularly preferably 10 to 100 cps.

The color former used in the present invention includes:
Triphenylmethanephthalide compounds such as crystal violet lactone, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, indolylazaphthalide compounds, leukoauramine compounds,
Various color formers such as rhodamine lactam compounds, triphenylmethane compounds, triazene compounds and spiropyran compounds can be used in combination. Among these,
Crystal violet lactone, benzoyl leuco methylene blue, fluorane compounds, indolyl phthalide compounds and indolyl azaphthalide compounds are preferred.

In producing the microcapsules containing the color former, the color former is dissolved in the solvent of the present invention to prepare a color former solution, but it may be heated if necessary. Further, the concentration of the color former in the color former solution is preferably 3 to 12% by weight, and particularly preferably 3 to 10% by weight based on the solvent.

The microcapsules containing the color former can be produced by any method known per se, for example, interfacial polymerization method, internal polymerization method, phase separation method, external polymerization method, coacervation method and the like. it can. The wall material of the microcapsule is water-insoluble, which is conventionally used as the wall material of the color-forming agent-containing microcapsule of the pressure-sensitive recording material.
Any oil-insoluble polymer can be used without particular limitation, and examples thereof include a polyurethane urea wall, a melamine / formaldehyde wall, and a gelatin wall. The wall material of the microcapsules is particularly preferably a polyurethane urea resin because of its high resistance to thermal fog.

The microcapsules having a polyurethane urea wall containing a color former as described above are emulsified and dispersed in a hydrophilic liquid by dissolving a solution of a polyvalent isocyanate, a polyvalent hydroxy compound and the electron donative color former in the solvent. Then, a polyvalent amine is added to the emulsified dispersion, and the hydrophobic droplets can be prepared by coating with a polyurethane urea film. The dispersion liquid containing the microcapsules thus obtained can be used as a coating liquid for forming a color former layer.

As the polyisocyanate used in the present invention, hydrogenated xylylene diisocyanate (generally called hydrogenated XDI) isocyanurate, isophorone diisocyanate (generally called IPDI) isocyanurate, 4,4 '. -Diphenylmethane diisocyanate, an adduct of hexamethylene diisocyanate and trimethylolpropane, biuret of hexamethylene diisocyanate, isocyanurate of hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, carbodiimide-modified diphenylmethane diisocyanate, tolylene diisocyanate and trimethylolpropane and Adduct of xylylene diisocyanate with trimethylol propane, Cyanurate, adduct of hydrogenated xylylene diisocyanate and trimethylolpropane, adduct of isophorone diisocyanate and trimethylolpropane, biuret of xylylene diisocyanate, and tris- (p-isocyanatophenyl) thiophosphite And the like.

Of these, hydrogenated xylylene diisocyanate isocyanurates and isophorone diisocyanate isocyanurates are preferable because of their excellent solubility in the solvent of the present invention. It is preferable to use a mixture of these two kinds of polyvalent isocyanate and aromatic polyvalent isocyanate, and the mixing ratio thereof is 8: 2 by weight.
The range of 2: 8 (two types: aromatic) is preferable, and particularly 7: 3.
The range of to 3: 7 is preferable.

The compound capable of polymerizing with a polyvalent isocyanate is
Water, a polyhydroxy compound and / or a polyamine. Specific examples of the above polyhydric hydroxy compound include aliphatic or aromatic polyhydric alcohols, hydroxy polyesters, hydroxy polyalkylene ethers, and alkylene oxide adducts of polyvalent amines.

The above-mentioned polyvalent amine compound is a compound having two or more --NH-- groups or --NH ₂ groups in the molecule and soluble in a hydrophilic liquid. Specific examples of the polyvalent amine compound include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,3-propylenediamine, hexamethylenediamine, phenylenediamine, diaminonaphthalene,
Examples include xylylenediamine and the like.

The dispersion liquid of the microcapsules prepared as described above is used as it is as a coating liquid for forming a color former layer, or a binder, a capsule protecting agent and the like are further added to this microcapsule dispersion liquid to form a color former layer. A coating liquid for formation is prepared, coated on a support by a method known per se, and dried to form a color former layer of a carbonless paper pressure-sensitive recording material. As the binder, a water-soluble binder, a latex binder or the like can be used, and as the capsule protecting agent, cellulose powder, starch particles, talc or the like can be used.

As the support, any support conventionally used as a support for pressure-sensitive recording materials and heat-sensitive recording materials, for example, paper from wood pulp, surface-treated paper of this paper, plastics material Synthetic paper, plastics film, etc. from can be used.

The final coating amount of the color former to be coated on the support is
0.05-0.30 g / m ² , preferably 0.08-
0.20 g / m ² is suitable.

The color developer contained in the color developing layer of the carbonless paper type pressure-sensitive recording material (eg color developing agent sheet) of the present invention includes a metal salt of aromatic carboxylic acid (eg salicylic acid derivative). , Organic form developers such as phenol formaldehyde resin are used. Of these, aromatic carboxylic acid metal salts are preferable. Specific preferred examples of the metal salt of aromatic carboxylic acid include 3,5-di-t-butylsalicylic acid,
3,5-di-t-octylsalicylic acid, 3,5-di-t
-Nonylsalicylic acid, 3,5-di-t-dodecylsalicylic acid, 3-methyl-5-t-dodecylsalicylic acid, 3-
t-dodecylsalicylic acid, 5-t-dodecylsalicylic acid, 5-cyclohexylsalicylic acid, 3,5-di-α-
Methylbenzyl salicylic acid, 3-methyl-5- (α-methylbenzyl) salicylic acid, 3- (α, α-dimethylbenzyl) -5-methylsalicylic acid, 3- (α, α-dimethylbenzyl) -6-methylsalicylic acid, 3- (α-methylbenzyl) -5- (α, α-dimethylbenzyl) salicylic acid, 3- (α, α-dimethylbenzyl) -6-ethylsalicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) ) Zinc salts, nickel salts, aluminum salts of salicylic acid, carboxy-modified terpene phenol resin, salicylic acid resin, which is a reaction product of 3,5-bis (α-methylbenzyl) salicylic acid and benzyl chloride, etc.,
Calcium salt etc. can be mentioned. The organic liquid used in the solvent of the present invention has a viscosity at 25 ° C. when the above organic developer is dissolved to form a 35% by weight solution.
Indicates 0 cps or less.

The above-mentioned metal salt of aromatic carboxylic acid can be mechanically dispersed in an aqueous system or dissolved in an organic solvent before use.

When the aromatic carboxylic acid metal salt is mechanically dispersed, it can be treated with a ball mill, an art writer, a sand grinder or the like to prepare a dispersion liquid.

As the organic solvent for dissolving the aromatic carboxylic acid metal salt, diisopropylnaphthalene, 1-phenyl-1-xylylethane, 1-phenyl-1-isopropylphenylethane, 1-phenyl-1-ethylphenylethane, toluene, Examples thereof include xylene, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, ethyl acetate, butyl acetate, amyl acetate, methylene chloride, butanol, paraffin and kerosene.

A solution in which an aromatic carboxylic acid metal salt is dissolved in the above organic solvent is added to the dispersion-containing water in an amount of 5 to 120% by weight, preferably 50 to 100% by weight, and emulsified and dispersed. Subsequently, the emulsified dispersion may be heated to remove the organic solvent. The aromatic carboxylic acid metal salt is generally used by dissolving it in an organic solvent in an amount of 10 to 200% by weight.

As the dispersant, an ionic or nonionic surfactant or a water-soluble polymer compound can be used. Examples of the surfactant include alkylbenzene sulfonate, alkylnaphthalene sulfonate, alkyl sulfonate, dialkyl sulfosuccinate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyhydric alcohol fatty acid partial ester and the like. . Examples of the water-soluble polymer compound include polyvinyl alcohol, modified polyvinyl alcohol, polyacrylamide, sodium polyacrylate, polyvinyl ether, sodium polystyrene sulfonate, and maleic anhydride copolymer.

The coating liquid for forming the above-mentioned developer layer contains, as a binder, a styrene / butadiene copolymer latex, a vinyl acetate latex, an acrylic ester latex, polyvinyl alcohol, polyacrylic acid, maleic anhydride. / Styrene copolymer, carboxymethylcellulose, synthetic polymers such as methylcellulose,
Alternatively, natural polymers such as starch, casein, gum arabic and gelatin may be added.

The final coating amount of the color developer applied to the support is
^{0.1g / m 2 ~3.0g / m 2} , preferably 0.2g
/ M ^{2 to} 1.0 g / m ² is suitable.

[0038]

【Example】

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[Example 1] [Preparation of coating liquid for forming color former layer] As a color former, 6.5 g of crystal violet lactone and 1.5 g of benzoyl leuco methylene blue were mixed with a mixture of tetramethylbenzene isomers (Sure Sol). -150, Coke
It was dissolved in 150 g of a chemical company (Koch Chemical Company, boiling point 180 ° C.).

The obtained oily liquid was added with carbodiimide-modified diphenylmethane diisocyanate (Millionate MTL, Nippon Polyurethane Co., Ltd.) as a polyvalent isocyanate.
Made, solid content 100%) 10.0 g and hexamethylene diisocyanate burette body (Sumijour N320)
5.0 g, manufactured by Sumitomo Bayer Urethane Co., Ltd., and butylene oxide adduct of ethylenediamine (addition mole number of butylene oxide to ethylenediamine 16.
A primary solution was prepared by dissolving 3.0 g of 8 mol and a molecular weight of 1267.

Next, 15 g of polyvinyl alcohol was dissolved in 135 g of water by heating in a stainless steel container to prepare a secondary solution. While vigorously stirring the secondary solution, the primary solution was poured into the secondary solution to form an oil-in-water emulsion. Oil droplet size is 6.0 μm
When it becomes, reduce the agitation and then add 2 to this emulsion.
After adding a 0.5 wt% aqueous solution of tetraethylenepentamine at 0 ° C, the system temperature was gradually raised to 80 ° C and maintained at this temperature for 120 minutes to prepare a capsule dispersion liquid. The resulting capsule dispersion was cooled to 20 ° C.

100 g of a 10% by weight aqueous solution of polyvinyl alcohol, 20 g of carboxy-modified SBR latex (48% by weight) and 50 g of starch particles (average particle size 15 μm) were added to the thus obtained capsule liquid. Next, water was added to adjust the solid content concentration to 15% by weight to prepare a color developer layer-forming coating liquid (microcapsule dispersion liquid) containing microcapsules containing the color developer.

[Preparation of Coloring Agent Sheet] 4.0 g / m ² of the above coating solution for forming a coloring agent layer was coated on one side of a base paper of 50 g / m ^2.
The solid content of ² was applied using an air knife coater and dried to prepare a color former sheet.

[Preparation of coating liquid for forming developer layer] 3,5-
1 part by weight of 10 parts by weight of zinc di-α-methylbenzyl salicylate
-Isopropylphenyl-2-phenylethane (20 parts by weight) was added and the mixture was heated at 90 ° C to be dissolved. Next, this solution was added to 50 parts by weight of a 2% by weight aqueous solution of polyvinyl alcohol (Kuraray Co., Ltd., trade name "PVA-203"), and 0.1% by weight of a 10% aqueous sodium sulfosuccinate solution as a surfactant. Was added and emulsified using a homogenizer to prepare an emulsion having an average particle size of 3 μm.

Next, 80 parts by weight of calcium carbonate, 20 parts by weight of zinc oxide and 1 part by weight of sodium hexametaphosphate were added to 200 parts by weight of water and dispersed using a Keddy mill to prepare a dispersion liquid. After mixing this with the emulsion, 100 parts by weight of a 10% by weight aqueous solution of polyvinyl alcohol (Kuraray Co., Ltd., trade name "PVA-110") and a carboxy-modified styrene / butadiene latex (SN-307, as a binder) were added. Sumitomo Nogatax Co., Ltd. 10 parts by weight (solid content) was added, and water was added to adjust the solid content concentration to 20% by weight to prepare a coating liquid for forming a color developer layer.

[Preparation of color developer sheet (lower paper)] 50 g
/ M ² of the base paper is coated on one side with a bar coater so that a solid content of 5.0 g / m ² is coated on the one surface of the base paper, dried, and the developer is formed. A sheet was prepared.

Example 2 [Preparation of Coloring Agent Sheet] 150 g of tetramethylbenzene isomer mixture (Sure Sol-150) used in the preparation of the coating solution for forming the coloring agent layer in Example 1
And Example 1 except that a mixed solvent (boiling point 180 ° C.) of 22.5 g of a mixture of tetramethylbenzene isomers (Sure Sol-150) and 127.5 g of diisopropylnaphthalene (boiling point 280 ° C.) was used. A color developer sheet was prepared in the same manner as in Example 1 using the color developer layer forming coating solution prepared in the same manner. Further, a color developer sheet was prepared in the same manner as in Example 1.

[Comparative Example 1] [Preparation of Coloring Agent Sheet] A mixture of isomers of tetramethylbenzene (Sure Sol-150) used in the preparation of the coating solution for forming the coloring agent layer in Example 1 was prepared. Instead, a color former sheet was prepared in the same manner as in Example 1 by using the color developer layer-forming coating solution prepared in the same manner as in Example 1 except that the same amount of diisopropylnaphthalene (boiling point 280 ° C.) was used. did. Further, a color developer sheet was prepared in the same manner as in Example 1.

[Comparative Example 2] [Preparation of Coloring Agent Sheet] A mixture of tetramethylbenzene isomers (Sure Sol-150) used in the preparation of the coating solution for forming the coloring agent layer in Example 1 was prepared. Instead, 1-xylyl-1-phenylethane (boiling point 293
A coloring agent sheet was prepared in the same manner as in Example 1 except that the same amount of (.degree. C.) was used and the coating liquid for forming a coloring agent layer prepared in the same manner as in Example 1 was used. Further, a color developer sheet was prepared in the same manner as in Example 1.

Comparative Example 3 [Preparation of Coloring Agent Sheet] The mixture of tetramethylbenzene isomers (Sure Sol-150) used in the preparation of the coating solution for forming the coloring agent layer in Example 1 was prepared. Instead, a color developer sheet was prepared in the same manner as in Example 1 using the color developer layer forming coating solution prepared in the same manner as in Example 1 except that the same amount of monoisopropyl biphenyl (boiling point 285 ° C.) was used. It was made. Further, a color developer sheet was prepared in the same manner as in Example 1.

[Evaluation test] (1) Viscosity of color developer solution The solvent used for dissolving the color developer in Examples and Comparative Examples was used in the developer liquid for forming the color developer layer, 3,5-di. Zinc -α-methylbenzylsalicylate (developing agent) was dissolved into a 35 wt% solution, and the solution viscosity at 25 ° C was measured using a B-type viscometer (type BL, manufactured by Tokyo Keiki Co., Ltd.). . (2) Coloring Density The color-developing agent sheet and the color-developing agent sheet prepared above are stacked,
Under the environment of 5 ° C., pressure was applied to the entire surface of the color developing agent sheet, and the developer layer was solidly colored. Macbeth reflection of the color density (D) of the color developer layer 15 seconds after color development and the color density (D) of the color developer layer after leaving the obtained color image for 24 hours in an environment of -5 ° C. It measured using the densitometer. (3) Color development speed The color development speed was determined from the following formula using the above color development density. (A / b) × 100 (%) a: Color density of developer layer 15 seconds after color development (D) b: Color density of developer layer 24 hours after color development (D)

The above results are shown in Table 1.

[0054]

[Table 1] Table 1 ──────────────────────────────────── Solution viscosity Coloring density Coloring speed (cps) ) 15 seconds later 24 hours later (%) ──────────────────────────────────── Example 1 20 0.64 0.79 81 Example 2 160 0.39 0.80 49 ───────────────────────────────── Comparative Example 1 630 0.24 0.80 30 Comparative Example 2 310 0.29 0.81 36 Comparative Example 3 220 0.36 0.80 45 ───────────── ───────────────────────

[0055]

INDUSTRIAL APPLICABILITY The recording material of the present invention is improved by using a specific organic solvent capable of lowering the viscosity when the organic developer is dissolved, as a solvent for dissolving the color former. It is possible to form a colored image having a coloring density in a short time even in a low temperature environment, and thus it can be said that the recording material has an improved coloring speed.

Claims (2)

[Claims] 1. A recording material comprising a microcapsule containing an electron-donating color former dissolved in a solvent and an electron-accepting developer, wherein the electron-accepting developer is an organic color developer. 175, which is a developing agent, and in which the solvent of the color former is capable of dissolving the organic developer and the viscosity of a 35 wt% solution of the organic developer at 25 ° C. is 200 cps or less. A recording material which is an organic liquid having a temperature of ℃ or higher. 2. The recording material according to claim 1, wherein the organic developer is at least one of a metal salt of an aromatic carboxylic acid and a phenol formaldehyde resin.