JP2010059348A - Microcapsule ink, method of producing the same, and carbonless pressure-sensitive copying paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for a producing a microcapsule ink containing few coarse particles formed by aggregation of microcapsules and being appropriate for hot-melt printing. <P>SOLUTION: The microcapsule ink containing microcapsules and hot-melt wax as main components is produced by heating and agitating microcupsule-containing powder that is obtained by spraying and drying a mixed aqueous dispersion of an aqueous dispersion of synthetic resin film microcapsule prepared in an aqueous medium and an aqueous dispersion of hot-melt wax (A) having a melting point ranging from 50-90°C to a melting point or higher of the hot-melt wax (A) and the hot-melt wax (B) together with the hot-melt wax (B), so as to disperse the microcapsules in hot-melt wax. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a microcapsule ink and a method for producing the same, and as one application thereof, partially prints a microcapsule ink containing an electron-donating color former (hereinafter referred to as a color former) as a core material of the microcapsule. The carbonless pressure-sensitive copying paper obtained by

  Microcapsules are used in a wide variety of fields such as recording materials, fragrances, pharmaceuticals, agricultural chemicals, insecticides, fertilizers, heat storage materials, adhesives, rust inhibitors, liquid crystals, enzymes, catalysts, artificial blood, etc. A typical application is a carbonless pressure-sensitive copying paper that is used for copy recording by microencapsulating a color former and utilizing a color development reaction with a developer. It is also known that a color former-encapsulating microcapsule is converted into an ink and printed on a part of a support to form a partially-printed carbonless pressure-sensitive copying paper.

  As a method for producing a microcapsule, a coacervation method, an in situ polymerization method, an interfacial polymerization method and the like are known as representative methods. The coacervation method uses phase separation by electrical interaction between gelatin, which is an amphoteric polymer electrolyte, and gum arabic, carboxymethyl cellulose, and the like, which are anionic polymer electrolytes. The in situ polymerization method is a method in which a monomer and a polymerization catalyst of a film material are supplied from only one of the inner side and the outer side of the core material, and a polymer film is formed by polymerization or condensation of the monomer on the surface of the core material. Resins, melamine-formaldehyde resins, and the like are known as coating materials. The interfacial polymerization method is a method in which different types of monomers are contained in both the core material and its medium, and a polymer film is formed on the interface between the two, that is, the surface of the core material. Polyurea resin, polyurethane urea resin, polyamide resin Are known as coating materials.

  As inks using microcapsules, inks corresponding to various printing methods are known, and for example, flexographic printing types, letterpress / lithographic printing types, hot melt printing types and the like are known (for example, Patent Documents 1 to 5). . Carbonless pressure-sensitive copying paper using these inks is also known (for example, Patent Documents 6 to 8).

  There are various problems in making microcapsules into ink and producing partially printed paper. An explanation will be given by taking a carbonless pressure-sensitive copying paper, which is a typical use of microcapsules, as an example. Generally, the amount of ink that can be printed by a printing press is about 1 to 5 μm as the ink film thickness, excluding a special method called silk screen. The volume average particle diameter of color former microcapsules used in conventional carbonless pressure-sensitive copying paper is about 3 to 10 μm, and among them, there are a plurality of large-sized microcapsules and small-sized microcapsules. Aggregated coarse particles are included, and large particles exceeding the ink film thickness protrude from the ink film and may be destroyed by a slight external rubbing pressure. In the case of carbonless pressure-sensitive copying paper of the entire surface water-coated type, a material that protects microcapsules with a volume average particle diameter of about 20 μm, called a stilt material, is used together. Can do. However, in the case of printing ink, there is a limitation on the ink film thickness, so that a tilt material cannot be used.

  In addition, microcapsules are usually produced in the form of an aqueous slurry, but are generally converted into ink after being once dried into a solid state. However, the microcapsules dried in solid form are agglomerated, and it is not easy to re-disperse into single particles to form an ink. For this reason, particles much larger than the ink film thickness exist, and as described above, they are destroyed by a slight external rubbing pressure.

As a method for solving such inconvenience, the present inventor adds a higher fatty acid amide or a higher fatty acid metal salt to the microcapsule aqueous dispersion in the microcapsule aqueous dispersion drying step, mixes and dries, A method for preventing microcapsules from agglomerating and producing microcapsules free from abnormal destruction has been disclosed (Patent Document 9). These higher fatty acid-based additives played a role as a spacer between the microcapsule particles, and had good affinity for organic solvents and varnishes for offset ink, and improved the dispersibility of the microcapsules. Compatibility with non-polar hot-melt waxes often used in hot-melt inks is not sufficient, and for hot-melt printing microcapsule inks, further improvement in microcapsule dispersibility is desired. It was.
Japanese Examined Patent Publication No. 62-5196 Japanese Patent Publication No. 63-52596 Japanese Patent Publication No. 2-30878 Japanese Patent Publication No. 3-59836 Japanese Patent No. 3147184 JP 60-149489 A Japanese Patent Publication No. 63-52597 Japanese Patent Publication No. 2-53238 Japanese Patent No. 3433853

  The present invention relates to a method for producing a microcapsule ink suitable for hot-melt printing, and an object thereof is to provide a method for producing a microcapsule ink with few coarse particles due to aggregation of microcapsules.

  In a microcapsule ink mainly composed of a microcapsule and a heat-meltable wax, the microcapsule is a synthetic resin film microcapsule prepared in an aqueous medium, and the aqueous dispersion of the microcapsule and the melting point are 50 to 90 ° C. The microcapsule-containing powder obtained by spray-drying an aqueous dispersion mixed with an aqueous dispersion of the hot-melt wax (A) is mixed with the hot-melt wax (A) and the heat together with the hot-melt wax (B). The above problem can be solved by heating and stirring to a melting point or higher of the melting wax (B) to disperse the microcapsules in the hot melting wax.

  Furthermore, as a microcapsule, by using a microcapsule whose membrane material is melamine-formaldehyde resin and whose volume average particle size is 1 to 3 μm, the volume average particle size of the aqueous dispersion of the hot-melt wax (A) is used. By setting the thickness to 0.3 to 3 μm, a good microcapsule ink can be obtained.

  By using the method for producing a microcapsule ink according to the present invention, it is possible to obtain a microcapsule ink suitable for hot-melt printing with few coarse particles due to aggregation between microcapsules. Carbon-free color-coating paper for carbonless pressure-sensitive copying paper by this method Partial-printing type carbon-free pressure-sensitive copying paper on paper is less likely to cause color stains due to rubbing and breaking of coarse particles. By printing only on the parts necessary for color development, the amount of expensive materials used can be reduced and resource saving can be achieved.

Below, the manufacturing method of the microcapsule ink of this invention is demonstrated in detail.
As described above, various methods for producing microcapsules are known. In the present invention, methods for producing microcapsules such as an in-situ method and an interfacial polymerization method using a synthetic resin as a film material can be used. . In-situ microcapsules with melamine-formaldehyde or urea-formaldehyde resin film are excellent in solvent resistance, especially microcapsules with melamine-formaldehyde resin film are excellent in heat resistance and easy to powder. preferable.

  In the production of melamine-formaldehyde resin film microcapsules, any dispersant that is added to an aqueous medium to emulsify and disperse the core substance can be used as long as it is thermally stable and suitable for microencapsulation. Yes, a cationic, anionic, nonionic or amphoteric water-soluble polymer compound is used, ethylene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, Water-soluble salts of maleic anhydride copolymers such as styrene-maleic anhydride copolymers, acrylic acid or methacrylic acid polymers and copolymer compounds, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, sulfone-modified polyvinyl alcohol, etc. And the following synthetic polymers. In particular, use of a water-soluble salt of maleic anhydride copolymer is preferred.

  The core material may be a hydrophobic material that can be emulsified and dispersed in an aqueous medium using the above-described dispersant, and includes recording materials, fragrances, pharmaceuticals, agricultural chemicals, insecticides, fertilizers, heat storage materials, adhesives, and rust inhibitors. A material capable of microencapsulation can be appropriately selected from materials useful in the fields of liquid crystal, enzyme, catalyst, artificial blood and the like.

  For carbonless pressure-sensitive copying paper, a solution in which an electron-donating color former is dissolved in a known hydrophobic liquid is used. Examples of the hydrophobic liquid include phenylxylylethane, phenylisopropylphenylethane, phenylbutylphenylethane, and the like. Diarylalkane compounds, alkylnaphthalene compounds such as monoisopropylnaphthalene and diisopropylnaphthalene, alkylbiphenyls such as monoisopropylbiphenyl and diisopropylbiphenyl, partially hydrogenated terphenyl compounds, alkylbenzene compounds, paraffins, vegetable oils, fatty acid ester compounds, etc. It is done.

  As the electron-donating color former, known compounds for carbonless pressure-sensitive copying papers can be used alone or in combination, such as triphenylmethane compounds, phenothiazine compounds, indolylphthalide compounds, indolyl aza. Examples include phthalide compounds, leucooramine compounds, spiropyran compounds, and the like. These color formers are dissolved or dispersed in a hydrophobic liquid so as to have a concentration of about 0.1 to 20% by mass, preferably about 1 to 10% by mass.

  The volume average particle size of the microcapsules used in the present invention is preferably 0.5 to 10 μm, but most preferably in the range of 1 to 3 μm. When the volume average particle diameter is smaller than 0.5 μm, the microcapsule is difficult to break when exposing the core substance by exposing the core material, and the exposure efficiency may be lowered, and the volume average particle diameter exceeds 10 μm. Then, since the physical strength is lowered, there is a possibility that undesired destruction of the microcapsule occurs.

  The microcapsules used in the present invention are usually prepared in the form of an aqueous dispersion, which is dehydrated and dried for use in ink. As the drying apparatus, a spray dryer apparatus capable of obtaining fine powder particles is preferable, and it is desirable that the drying apparatus is pulverized by drying so that the water content is 5% or less, preferably 2% or less.

  Examples of the aqueous dispersion of the hot-melt wax (A) having a melting point of 50 to 90 ° C. mixed with the microcapsule aqueous dispersion at the time of pulverization include carnauba wax, montan wax, paraffin wax, and microcrystalline wax. In addition, an oxide wax or the like dispersed in an aqueous medium is used. When the melting point of the heat-meltable wax (A) is less than 50 ° C., the wax melts at the time of drying by heating and the effect as a spacer is reduced, which is not desirable. In addition, the microcapsule-containing powder is heated together with the heat-melting wax (B) to melt the wax component to make an ink. When the melting point of the heat-melting wax (A) exceeds 90 ° C., The particles of the heat-meltable wax (A) contained in the inner part of the capsule-containing powder are difficult to melt, and the effect of improving dispersibility is difficult to obtain.

  The volume average particle diameter of the aqueous dispersion of the hot-melt wax (A) is preferably in the range of 0.3 to 3 μm. When the volume average particle diameter is less than 0.3 μm, in order to heat and sufficiently disperse the obtained dried microcapsules in the hot-melt wax (B), the number of hot-melt waxes (A) is large in number. Need particles. In addition, when the volume average particle diameter exceeds 3 μm, a large amount of heat-meltable wax (A) is required in volume in order for the wax particles to be efficiently present between the microcapsule particles, and production of microcapsule-containing powder is required. Efficiency is reduced.

  The solid mass ratio between the microcapsules and the heat-meltable wax (A) depends on the respective volume average particle diameters, but the heat-meltable wax (A) is preferably in the range of 0.1 to 3 with respect to the microcapsules 1. .

  As the heat-meltable wax (B) used in the present invention, waxes having a melting point of about 50 to 120 ° C. generally used in hot-melt carbon inks are used. Specific examples include wax, Carnauba wax, montan wax, paraffin wax, microcrystalline wax, polyethylene wax, oxide wax, higher fatty acids, higher alcohols, higher fatty acid amides, higher fatty acid esters, etc. may be used alone or in appropriate mixtures. Can do.

  The hot-melt wax (A) and the hot-melt wax (B) may be the same type of wax or may be different. Each melting point can be used within the above range, but the melting point of the hot-melt wax (A) is better or lower than the melting point of the hot-melt wax (B). It is preferable in obtaining.

  In the microcapsule ink, coloring pigments, extender pigments and oils can be added as necessary. Examples of oils include mineral oils such as machine oil and motor oil, and non-drying oils such as castor oil. be able to.

  The hot-melt wax (A) plays a role as a spacer for the microcapsules during pulverization and is relatively easy to melt at a melting point of 50 to 90 ° C. Compared to the hot-melt wax (B). Because it is a material with good mechanical compatibility, the heat-meltable wax (A) present in the microcapsule agglomerated particles melts and melts into the heat-meltable wax (B) when it is heated and stirred to form an ink. Thus, it is presumed that the effect of promoting the dispersion of the microcapsule particles occurs.

  Hereinafter, the present invention will be described in more detail by way of examples. As a typical application example of the microcapsule, a carbonless pressure-sensitive copying paper will be described as an example, but the present invention is not limited to this embodiment. In addition, the number of parts and percentage in an Example are based on solid mass.

(Preparation of color former microcapsule A)
A solution obtained by dissolving 10 parts of CVL (crystal violet lactone), which is an electron-donating color former, in 190 parts of a high boiling point hydrocarbon oil (manufactured by Shin Nippon Oil Co., Ltd., trade name: Hysol SAS / N-296) is styrene / anhydrous In addition to 200 parts of a 5% aqueous solution of a maleic acid copolymer, the mixture was emulsified and dispersed with an emulsifier (Primics Co., Ltd., TK Robotics) until the volume average particle size became 1.5 μm. Next, 30 parts of melamine, 45 parts of 37% formaldehyde aqueous solution, and 80 parts of water were heated and dissolved at pH 9.5 to prepare a melamine / formaldehyde initial condensate. This is added to the above emulsified dispersion and stirred at 75 ° C. for 2 hours, then the pH is adjusted to 9.5, the solid content concentration is adjusted to 45%, and the slurry-like color former microcapsule A having a melamine / formaldehyde resin as a film is used. Got.

(Preparation of color former microcapsule B)
A slurry-like color former microcapsule B was obtained in the same manner as in the production of the color former microcapsule A except that the emulsified dispersion volume average particle diameter was 3 μm.

(Preparation of color former microcapsule C)
A slurry-like color former microcapsule C was obtained in the same manner as in the production of the color former microcapsule A except that the emulsified dispersion volume average particle diameter was 5 μm.

(Preparation of color former microcapsule D)
A slurry-like color former microcapsule D was obtained in the same manner as in the production of the color former microcapsule A except that the emulsified dispersion volume average particle diameter was 0.8 μm.

(Preparation of color former microcapsule E)
10% of an ethylene / maleic anhydride copolymer is obtained by dissolving 10 parts of CVL (crystal violet lactone), which is an electron donating color former, in 190 parts of high boiling point hydrocarbon oil (trade name: Hysol SAS / N-296). In addition to 200 parts of the aqueous solution, the mixture was emulsified and dispersed with an emulsifier (trade name: TK Robotics) until the volume average particle size became 3 μm. Next, 20 parts of urea, 2 parts of resorcin, 45 parts of a 37% formaldehyde aqueous solution, and 80 parts of water were added and stirred at 75 ° C. for 3 hours, then the pH was adjusted to 8 and the solid content concentration was adjusted to 45%. A slurry color former microcapsule E having a resin film was obtained.

(Preparation of perfume microcapsules)
A slurry-like fragrance microcapsule in the same manner as in the production of the color former microcapsule A, except that 10 parts of CVL is 10 parts of fragrance oil (trade name: THP-10881, manufactured by Hasegawa Fragrance Co., Ltd.) and the volume average particle diameter is 3 μm. Got.

Example 1
To 67 parts (solid mass) of slurry color former microcapsule A, a paraffin wax emulsion (manufactured by Chukyo Oil & Fats Co., Ltd., trade name: Hydrin L-703-35) having a melting point of 70 ° C. and a volume average particle size of 1.0 μm. 33 parts (solid mass) is mixed and an aqueous dispersion adjusted to a solid content concentration of 30% is supplied to a spray dryer (manufactured by Niro Japan Co., Ltd., mobile minor type), and the atomizer speed is 30,000 rpm The powder A-1 containing color former microcapsules having a water content of 1% was obtained under the drying conditions of 1 minute / minute, an inlet temperature of 270 ° C, and an outlet temperature of 105 ° C.

(Example 2)
Except for replacing the slurry color former microcapsule A with the slurry color former microcapsule B, a powder B-1 containing color former microcapsules having a water content of 1% was obtained in the same manner as in Example 1.

(Example 3)
Except for changing the slurry color former microcapsule A to the slurry color former microcapsule C, a powder C-1 containing color former microcapsules having a water content of 1% was obtained in the same manner as in Example 1.

Example 4
Except that the slurry color former microcapsules A were replaced with the slurry color former microcapsules D, a color former microcapsule-containing powder D having a water content of 1% was obtained in the same manner as in Example 1.

(Example 5)
Except for replacing the slurry-like color former microcapsule A with the slurry-like color former microcapsule E, a colorant microcapsule-containing powder E having a moisture content of 1% was obtained in the same manner as in Example 1.

(Example 6)
Except for replacing the paraffin wax emulsion with a paraffin wax emulsion having a melting point of 53 ° C. and a volume average particle size of 0.5 μm (manufactured by Chukyo Oil & Fats Co., Ltd., trade name: Cellosol 428), the moisture content is 1%. A powdery color former microcapsule-containing powder A-2 was obtained.

(Example 7)
In the same manner as in Example 1, except that the paraffin wax emulsion was changed to a montanate ester wax emulsion (manufactured by Chukyo Yushi Co., Ltd., trade name: Hydrin J-537) having a melting point of 83 ° C. and a volume average particle size of 1.0 μm. 1% of color former microcapsule-containing powder A-3 was obtained.

(Example 8)
In the same manner as in Example 1 except that the paraffin wax emulsion was replaced with a carnauba wax emulsion having a melting point of 83 ° C. and a volume average particle size of 0.2 μm (manufactured by Chukyo Yushi Co., Ltd., trade name: Cellosol 524), the water content was 1%. Coloring agent microcapsule-containing powder A-4 was obtained.

Example 9
In the same manner as in Example 4 except that the paraffin wax emulsion was replaced with a carnauba wax emulsion having a melting point of 83 ° C. and a volume average particle size of 0.3 μm (manufactured by Chukyo Yushi Co., Ltd., trade name: Cellozol K-375), the water content was 1 % Color former microcapsule-containing powder D-2 was obtained.

(Example 10)
Except for changing the paraffin wax emulsion to a paraffin wax emulsion having a melting point of 75 ° C. and a volume average particle size of 3.0 μm (manufactured by Chukyo Yushi Co., Ltd., prototype P-150), the moisture content is 1%. Color developing agent microcapsule-containing powder B-2 was obtained.

(Example 11)
A powder containing fragrance microcapsules having a moisture content of 1% was obtained in the same manner as in Example 1 except that the slurry color former microcapsules A were replaced with slurry fragrance microcapsules.

(Comparative Example 1)
Coloring agent microcapsule-containing powder A-5 was obtained in the same manner as in Example 1 except that the paraffin wax emulsion was not used.

(Comparative Example 2)
A color former micro was prepared in the same manner as in Example 1 except that the paraffin wax emulsion was changed to a zinc stearate emulsion having a melting point of 120 ° C. and a volume average particle size of 0.2 μm (manufactured by Chukyo Yushi Co., Ltd., trade name: Hydrin F-115). Capsule-containing powder A-6 was obtained.

(Comparative Example 3)
A color former microcapsule-containing powder B-3 was obtained in the same manner as in Example 2 except that the paraffin wax emulsion was not used.

(Comparative Example 4)
A color former microcapsule-containing powder C-2 was obtained in the same manner as in Example 3 except that the paraffin wax emulsion was not used.

(Comparative Example 5)
A color former microcapsule-containing powder D-3 was obtained in the same manner as in Example 4 except that the paraffin wax emulsion was not used.

(Comparative Example 6)
Perfume microcapsule-containing powder fragrance-2 was obtained in the same manner as in Example 11 except that the paraffin wax emulsion was not used.

"Evaluation of dispersibility of powder containing microcapsules"
Disperse 10 g each of the color former microcapsule-containing powder obtained in Examples 1 to 10 and Comparative Examples 1 to 5 and the fragrance microcapsule-containing powder obtained in Example 11 and Comparative Example 6 in 100 g of liquid paraffin. And stirred for 1 hour while heating to 90 ° C. After cooling, the dispersed state of the microcapsule particles was observed with an optical microscope, and evaluated by the remaining state of the aggregated particles. The results are shown in Table 1. The rating is: ◎: good dispersion without aggregated particles, ○: some aggregated particles remain, but most are dispersed and practically usable, Δ: aggregated particles and single particles are mixed and slightly dispersed, x: aggregated particles A large amount remained and was poorly dispersed.

"Production of microcapsule ink"
36 parts of each of the color former microcapsule-containing powder obtained in Examples 1 to 10 and the fragrance microcapsule-containing powder obtained in Example 11 were mixed with paraffin wax having a melting point of 69 ° C. (Nippon Seiwa Co., Ltd.) 44 parts, carnauba wax (melting point 83 ° C) 15 parts, melting point 98 ° C higher fatty acid amide (Lion Co., Ltd., trade name: Armide HT) 5 parts heated to 100 ° C and stirred Example microcapsule inks 1 to 11 were obtained. In addition, 24 parts of each of the color former microcapsule-containing powder obtained in Comparative Examples 1 to 5 and the fragrance microcapsule-containing powder obtained in Comparative Example 6 were mixed with paraffin wax (Nippon Seiwa Co., Ltd.) having a melting point of 69 ° C. )) 56 parts, carnauba wax 15 parts, higher fatty acid amide (manufactured by Lion Co., Ltd., trade name: Armide HT) together with 5 parts, heated to 100 ° C. and stirred to obtain microcapsule inks 1 to 6 of comparative examples .

“Production of carbonless pressure-sensitive copying paper and spot printed paper”
After heat-melting the microcapsule inks 1 to 10 of the example and the microcapsule inks 1 to 5 of the comparative example, the ink deposit amount is about 5 g / m ^{2 on} a high quality paper at about 80 ° C. and a basis weight of 50 g / m ² Then, spot printing was performed to produce a carbonless pressure-sensitive copying paper / spot-printed paper.

  The obtained carbonless pressure-sensitive copy paper / spot-printed paper is superimposed on the commercially available paper under carbonless pressure-sensitive copying paper (Mitsubishi Paper Co., Ltd., trade name: NCR paper N50) and printed with a typewriter. The print color density was evaluated. Also, the upper and lower sheets were rubbed together in the same combination, and the degree of smearing was observed. Each of them was evaluated on the basis of the following criteria, and the results are shown in Table 1. 1: Defect, 2: Slightly defect, 3: Practical lower limit level, 4: Almost good, 5: Good

"Production and evaluation of perfume microcapsule coating sheet"
After heat-melting the microcapsule ink 11 of the example and the microcapsule ink 6 of the comparative example, at about 80 ° C., the basis weight is 50 g / m ^{2 so} that the ink deposit amount is about 5 g / m ^2. Spot printing was performed to prepare a perfume microcapsule coating sheet. When the printed portion was traced with a fingertip, the printed material of the comparative example was found to have irregularities on the surface that were thought to be due to aggregates, but the printed materials of the examples were good with no irregularities.

  From the results shown in Table 1, carbonless pressure-sensitive copying paper / spot printing using powder obtained by mixing a hot-melting wax aqueous dispersion having a melting point of 50 to 90 ° C. when drying the aqueous color former microcapsule dispersion It can be seen that the upper paper is less aggregated of color former microcapsules and less colored stains when rubbed against the lower paper. On the other hand, when the hot-melt wax aqueous dispersion was not used, or when the hot-melt wax aqueous dispersion having a melting point of more than 90 ° C. was mixed, an agglomerate considered to be due to the color former microcapsule was generated, It can be seen that color stains due to rubbing occur and the product value is low.

Claims (6)

  In a microcapsule ink mainly composed of a microcapsule and a heat-meltable wax, the microcapsule is a synthetic resin film microcapsule prepared in an aqueous medium, and the aqueous dispersion of the microcapsule and the melting point are 50 to 90 ° C. The microcapsule-containing powder obtained by spray-drying an aqueous dispersion mixed with an aqueous dispersion of the hot-melt wax (A) is mixed with the hot-melt wax (A) and the heat together with the hot-melt wax (B). A method for producing a microcapsule ink, wherein the microcapsules are dispersed in a heat-meltable wax by heating and stirring to a temperature equal to or higher than the melting point of the meltable wax (B).   The method for producing a microcapsule ink according to claim 1, wherein the synthetic resin film is a melamine-formaldehyde resin film, and the volume average particle diameter of the microcapsule aqueous dispersion is 1 to 3 µm.   The method for producing a microcapsule ink according to claim 1, wherein the volume average particle size of the aqueous dispersion of the hot-melt wax (A) is 0.3 to 3 µm.   The microcapsule ink obtained by the manufacturing method of Claims 1-3.   The microcapsule ink according to claim 4, wherein the microcapsule encloses one or both of an electron donating color former and an electron accepting developer separately as a core substance.   Carbonless pressure-sensitive copying paper obtained by partially printing the microcapsule ink obtained according to claim 5 on a support.