JP2014148593A - Ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an erasable ink composition capable of forming dense handwriting.SOLUTION: An ink composition contains a leuco dye, a developer, a liquid medium, and a microcapsule including a hard-to-volatile hydrophilic organic compound and a polar compound as an included substance.

Description

  The present invention relates to an ink composition that applies the color developing performance and color erasing performance of a leuco dye and is decolored or discolored by rubbing or the like.

2. Description of the Related Art Conventionally, a heat-sensitive decolorable ink composition that applies the color development performance and color erasing performance of a leuco dye is known. This includes a leuco dye that is an electron donor, a developer and an erasing agent that are electron acceptors, and makes use of coloring and decoloring by their interaction. Color develops when the developer acts on the leuco dye.
Patent Document 1 discloses that a decoloring agent that melts by heat such as rubbing to dissolve a leuco dye or a developer is encapsulated in a capsule together with the leuco dye and the developer, and is used for decoloring by heat. The melting of the agent dissolves the leuco dye and the developer, and when the decolorizer acts on the developer, the color developing effect of the leuco dye is lost, and the erasable ink that becomes decolored and the ballpoint pen using the same It is disclosed. This is because when the temperature decreases after decoloring, the decoloring agent coagulates and the leuco dye becomes a recolored state, and the handwriting recolors.
In addition, the invention described in Patent Document 2 is such that the freezing point of the melted state (thermal hysteresis) is adjusted by lowering the solidification point of the solution of the decolored colorant and the developer at the time of decoloring, and the erased handwriting Is set to a temperature of −5 ° C. or lower so that the color does not recur in higher temperature environments.

JP-A-9-124993 JP-A-17-298746

  In the inventions described in Patent Documents 1 and 2, the leuco dye, the developer, and the color erasing agent are used in combination of specific substances and in a specific blending ratio, so that the leuco dye and the color developer are erased. By dissolving at a temperature equal to or higher than the melting point of the agent, the coloring and decoloring states are controlled by the thermal hysteresis width of the dissolution medium. At this time, since the leuco dye is encapsulated as a microcapsule pigment together with a developer, a decoloring agent, and an additive, the ratio of the color developing component in the microcapsule pigment is low, and the decolorizing agent is used as a solvent when preparing the microcapsule pigment Therefore, the leuco dye is surrounded by a decoloring agent, the interaction with the developer is weakened, and the color of the microcapsule pigment is light.

  The present invention comprises a leuco dye, a developer, a liquid medium, and a microcapsule encapsulating a polar compound, and the microcapsule has a room temperature solid or a boiling point of 150 ° C. or higher between the capsule film and the polar compound. The gist is an ink composition in which a compound having one or more hydrophilic groups selected from a hydroxyl group, a carbonyl group, an amino group, and a polyoxyalkylene group, which is a liquid at room temperature, is arranged in a layered manner.

A leuco dye becomes a colored state by opening a lactone ring or the like by interaction with a developer having an active proton and taking a resonance structure.
Since the ink composition of the present invention encloses a polar compound in a microcapsule, the micrograph can be obtained by rubbing with an eraser, a resin molded body of a writing instrument body, or a rubber-like elastic body portion on a handwriting such as a letter written with the ink composition. When a force exceeding the breaking strength of the capsule is applied, the encapsulated polar compound oozes out, dissolves the leuco dye and the developer, and the polar group whose electron density is increased by unpaired electrons of the polar compound is revealed. The active state of the coloring agent is attracted and the interaction with the leuco dye in the colored state is inhibited, so that the colored state cannot be maintained and the handwriting is erased. In this way, the polar compound, which is a substance that eliminates the interaction between the leuco dye and the developer, is encapsulated in the capsule, and separated from the portion where the leuco dye and the developer exist, so that the leuco dye and the developer are separated. The color material component composed of the agent can be made high in concentration, and a dark handwriting can be formed.
In this way, the microcapsules enclosing the polar compound as a handwriting decolorant will inadvertently erase the handwriting if the polar compound oozes out before being destroyed. The microcapsule film is designed to have a dense structure so that the polar compound encapsulated in the microcapsule does not ooze out. However, the polar compound serving as the decolorizer is a volatile substance or has an affinity for the polar compound. When exposed to an environment in which the properties increase, the molecular motion of the polar compound becomes active and may leak from minute gaps existing in the film.
A compound having one or more hydrophilic groups selected from a hydroxyl group, a carbonyl group, an amino group, and a polyoxyalkylene group, which is a solid at room temperature or a liquid at room temperature having a boiling point of 150 ° C. or higher, is a microcapsule while incorporating water molecules into the hydrophilic group. Since it is contained on the inner surface, a layer that is incompatible with the polar compound is formed in the microcapsule, and as a coating agent in the microcapsule film, the oozing from the minute gaps of the film is suppressed. For this reason, since there is no leaching of the erasing liquid from the microcapsule and there is no inadvertent erasing of the handwriting, a dark handwriting can be maintained.

  Hereinafter, embodiments of the present invention will be described in detail.

The leuco dye is not particularly limited as long as it is a colorless or light-colored pigment and is an electron-donating dye and functions as a color former. Examples include diphenylmethane phthalide dyes, fluoran dyes, indolyl phthalide dyes, spiropyran dyes, rhodamine lactam dyes, azaphthalide dyes, and the like. Specific examples are given below, but the present invention is not limited to these.
For example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 2'-anilo-6-6- (N-ethyl-N-isopentylamino) -3'-methylspiro [phthalide-3 , 9 ′-(9H) xanthene] -3-one, 2′-methyl-6 ′-(Np-tolyl-Nethylamino) spiro [isobenzofuran-1 (3H), 9 ′-(9H) xanthene ] -3-one, 2-methyl-6- (N-ethyl-Np-tolylamino) fluorane, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3- (4-Diethylamino-2-methylphenyl) -3- (1-ethyl-1H-indol-3-yl) -4-azaphthalide, 9- (diethylamino) spiro [12H-benzo (a) xanthene-12,1 ′ (3'H)- Sobenzofuran] -3′-one, 2-methyl-6- (N-ethyl-Np-tolylamino) fluorane, 5-amino-3 ′, 6′-dihydroxyspiro [isobenzofuran-1 (3H), 9 '-(9H) xanthen] -3-one, 6'-diethylamino-1', 2'-benzofluorane, 6-amino-3 ', 6'-dihydroxyspiro [isobenzofuran-1 (3H), 9' -(9H) xanthen] -3-one, 3 ', 6'-bis (diethylamino) -2- (4-nitrophenyl) spiro [isoindole-1,9'-xanthen] -3-one, 2'- Anilino-6′-dibutylamino-3′-methylspiro [phthalide-3,9 ′-(9H) xanthen] -3-one, 2 ′-(phenylamino) -3-methyl-6- [ethyl (p-tolyl) Amine] Spiro [9H-Ki Nten] -9one, 1 ′-(3′H-isobenzofuran) -3-one, 6-diethylamino-2- [3- (trifluoromethyl) anilino] spiro [9H-xanthene-9,3 ′ (1 'H) -isobenzofuran] -1'-one, 3,3-bis [2- (4-dimethylaminophenyl) -2- (4-methoxyphenyl) ethenyl] 4,5,6,7-tetrachloroiso Benzofuran-1 (3H) -one, 2 '-(N-phenyl-N-methylamine) -6', 6 (Np-tolyl-N-ethylamino) spiro [isobenzofuran-1 (3H)]- 3-one, 6-nitro-3 ′, 6′-dihydroxyspiro [isobenzofuran-1 (3H), 9 ′-(9H) xanthen] -3-one, 3-methoxy-4-dedecoxystylinoquinoline Etc., and these are It can be used alone or in combination.
These leuco dyes develop color by opening a lactone ring or the like and taking a resonance structure by a compound having an active proton.
The amount of leuco dye added to the total amount of the ink composition is preferably 1 to 30% by weight. If the amount is less than 1% by weight, the handwriting density is low, and if it is 30% by weight or more, the viscosity of the ink composition is increased and the ejection property is lowered.

The developer develops the color of the leuco dye described above.
Examples of the developer that can be used include a compound having a phenolic hydroxyl group having an active proton and a metal salt thereof.
For example, tert-butylcatechol, n-stearylphenol, o-phenylphenol, hexafluorobisphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, dodecyl gallate, 2,2-bis (4 -Hydroxyphenyl) propane, 4,4'-dihydroxydiphenylsulfone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, bis (4-hydroxy) Phenyl) sulfide, 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -3-methylbutane, 1,1-bis (4-hydroxyphenyl) -2 -Methylpropane, 1,1-bis (4-hydroxyphenyl) n-hexa 1,1-bis (4-hydroxyphenyl) n-heptane, 1,1-bis (4-hydroxyphenyl) n-octane, 1,1-bis (4-hydroxyphenyl) n-nonane, 1,1 -Bis (4-hydroxyphenyl) n-decane, 1,1-bis (4-hydroxyphenyl) n-dodecane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) ) Ethyl propionate, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4-hydroxyphenyl) n -Heptane, 2,2-bis (4'-hydroxyphenyl) n-nonane, etc., and in addition, aromatic carboxylic acid and aliphatic carboxylic acid, carboxylic acid Even compounds such as metal salts of acids, phosphate esters and metal salts thereof, sulfonate esters and metal salts thereof, triazole compounds, thiourea and derivatives thereof, halohydrins, benzothiazoles, novolac-type phenol resins, etc. Good. These can be used alone or in combination.
Although the usage-amount of a color developer changes with kinds, 0.5-5 are preferable with respect to the leuco dye 1 in general.

  Further, when the leuco dye and the developer are not dissolved in the liquid medium to be used, the leuco dye and the developer are dissolved in acetone or methyl ethyl ketone in advance, and then dried, ground and pigmented. The average particle diameter is preferably 10 μm or less in consideration of dischargeability from the pen tip of a ballpoint pen. A preferable addition amount is 2 to 30% by weight.

Polar compounds are encapsulated in microcapsules and act as decolorizers. The leuco dye and the developer are dissolved to inhibit the interaction between the leuco dye and the developer in a colored state, and in view of encapsulation, it is preferably insoluble or hardly soluble in water.
The solubility in water is preferably about 1 g / 100 ml (20 ° C.) or less.
As ester compounds, diethyl adipate (0.01 g / 100 ml or less), dioctyl adipate (0.01 g / 100 ml or less), triethyl acetyl citrate (0.72 g / 100 ml), tributyl acetyl citrate (0.002 g / 100 ml) ), Methyl abietate (0.01 g / 100 ml or less), ethyl benzoate (0.1 g / 100 ml or less), benzyl benzoate (0.01 g / 100 ml or less), ethyl isovalerate (0.17 g / 100 ml or less) , Ethyl cinnamate (0.01 g / 100 ml or less), benzyl acetate (0.01 g / 100 ml or less), dibutyl oxalate (0.01 g / 100 ml or less), diethyl tartrate (0.01 g / 100 ml or less), stearic acid Amyl (0.01 g / 100 ml or less), stearin Ethyl (0.01 g / 100 ml or less), butyl stearate (0.01 g / 100 ml or less), dioctyl sebacate (0.008 g / 100 ml), diethyl phthalate (0.15 g / 100 ml or less), dioctyl phthalate (0 0.01 g / 100 ml or less), dibutyl phthalate (0.013 g / 100 ml), diisononyl phthalate (0.002 g / 100 ml), dimethyl phthalate (0.24 g / 100 ml), isoamyl propionate (0.1 g / 100 ml or less) ), Butyl propionate (0.1 g / 100 ml or less), methyl propionate (0.1 g / 100 ml or less), dibutyl maleate (0.01 g / 100 ml or less), benzyl formate (0.1 g / 100 ml or less), acetic acid Amyl (0.17g / 100ml), Isoaacetate (0.2 g / 100 ml), isobutyl acetate (0.63 g / 100 ml), 2-ethylhexyl acetate (0.3 g / 100 ml), cyclohexyl acetate (0.01 g / 100 ml or less), s-butyl acetate (0.62 g) / 100 ml), methyl cyclohexyl acetate (0.3 g / 100 ml), ethyl butyrate (0.5 g / 100 ml), isoamyl acetate (0.01 g / 100 ml or less), diphenyl phthalate (0.01 g / 100 ml or less), phthalic acid Dicyclohexyl (0.01 g / 100 ml or less), methyl 2-benzoylbenzoate (0.08 g / 100 ml), phenyl benzoate (0.01 g / 100 ml or less), diphenyl carbonate (0.0058 g / 100 ml), methyl diphenyl acetate ( 0.001 g / 100 ml), trimethyl citrate (0.01 g / 100 ml or less), methyl 3,4,5-trimethoxybenzoate (0.01 g / 100 ml or less), triphenyl phosphate (0.01 g / 100 ml), 4-methoxyphenylacetic anhydride (0. 01 g / 100 ml or less).
As compounds having a ketone group, acetophenone (0.01 g / 100 ml or less), diisobutyl ketone (0.01 g / 100 ml or less), diisopropyl ketone (0.43 g / 100 ml), di-n-propyl ketone (0.53 g / 100 ml). ), Methyl-n-amyl ketone (0.1 g / 100 ml or less), methyl isobutyl ketone (0.1 g / 100 ml or less), methylcyclohexanone (0.1 g / 100 ml or less), methyl-n-hexyl ketone (0.01 g / 100 ml or less), methyl-n-heptyl ketone (0.01 g / 100 ml or less), tetradecanophenone (0.01 g / 100 ml or less), 1-acetoxy-2-methoxy-4- (1-probenyl) benzene (0 .01 g / 100 ml or less), 3,5-diacetoxyacetate Phenone (0.01 g / 100 ml or less), 4-methoxybenzophenone (0.01 g / 100 ml or less), benzophenone (0.01 g / 100 ml or less), dicyclohexyl phenyl ketone (0.01 g / 100 ml or less), 1,3 diphenyl- 1,3-propanedione (0.01 g / 100 ml or less), 4-acetoxyacetophenone (0.01 g / 100 ml or less), acetonaphthone (0.01 g / 100 ml or less), 2,2-dimethoxy-2-phenylacetophenone (0. 01 g / 100 ml or less), 4,4-bicyclohexanone (0.01 g / 100 ml or less), 1,2-tricosanone (0.01 g / 100 ml or less) and the like.
As compounds having an amide group, diphenylurethane (0.1 g / 100 ml or less), acetanilide (0.56 g / 100 ml), lidocaine (0.41 g / 100 ml), myristic acid anilide (0.1 g / 100 ml or less), N- Examples include benzyl-β-alanine ethyl (0.1 g / 100 ml or less), N-acetyl-o-phenetidine (0.53 g / 100 ml), N-carboethoxyphthalimide (0.1 g / 100 ml or less), and the like.
In addition, acrylic resin, ketone resin, alkyd resin, xylene resin, and the like can be given. These can be used alone or in combination.

A compound having one or more hydrophilic groups selected from a hydroxyl group, a carbonyl group, an amino group, and a polyoxyalkylene group, which is a solid at room temperature or a liquid at room temperature having a boiling point of 150 ° C. or higher, has a layer incompatible with polar compounds in a microcapsule. As a coating agent in the microcapsule film, the oozing from fine gaps in the film is suppressed.
The compound having one or more hydrophilic groups selected from a hydroxyl group, a carbonyl group, an amino group, and a polyoxyalkylene group, which is a room temperature solid or a room temperature liquid having a boiling point of 150 ° C. or higher, is contained at the same time as microcapsule preparation. In addition, when blended at the time of preparing the emulsion, it can be easily present on the surface of the emulsion by the action of the emulsifier, and can be contained in the microcapsules.
Examples of the compound having one or more hydrophilic groups selected from a hydroxyl group, a carbonyl group, an amino group, and a polyoxyalkylene group that are such a room temperature solid or a room temperature liquid having a boiling point of 150 ° C. or higher include aromatic alcohols and polyhydric alcohols. Water-soluble polymers, sugars, sugar alcohols, urea compounds, and the like.
Examples of the aromatic alcohol and polyhydric alcohol include benzyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and polyethylene glycol.
Examples of water-soluble polymers include gum arabic, caraya gum, xanthan gum, carob gum, guar gum, guaiac gum, dalman gum, tragacanth, benzoin gum, locust bean gum, casein, agar, alginic acid, dextrin, dextran, carrageenan, gelatin, collagen, collagen, pectin, Polysaccharides such as starch, polygalacturonic acid, chitin, chitosan, elastin, heparin, heparinoid, heparin sulfate, heparan sulfate, hyaluronic acid, chondroitin sulfate, or derivatives thereof, ceramide, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxy Cellulose derivatives such as propylmethylcellulose, carboxymethylcellulose, carboxyethylcellulose, cellulose , Polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone, silicone resin, polyester resin, urethane resin, ethylene maleic anhydride resin, isobutylene maleic anhydride resin, styrene maleic anhydride resin, methyl vinyl ether maleic anhydride resin, acrylic resin, styrene sulfone An acid resin, a styrene acrylic resin, etc. are mentioned.
Examples of sugars, sugar alcohols, and urea compounds include polyhydroxys such as glycerin and pentaerythritol, sugars such as glucose, galactose, mannose, fructose, lactose, sucrose, maltose, raffinose, and agarose, triethanolamine, diethanolamine monoethanolamine, Examples include organic amines such as urea and salts thereof. These can be used alone or in combination.
In addition, when a surfactant that is substantially insoluble in the polar compound is used as the compound disposed between the polar compound and the microcapsule film, it selectively adsorbs on the surface of the polar compound and is compatible with the polar compound. This is preferable as a base point for forming a non-performing layer in the microcapsule.
Examples of such surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants.
Anionic surfactants include higher fatty acid salts, α-sulfo fatty acid methyl ester salts, alkylbenzene sulfonates, alkyl sulfate esters, alkyl ether sulfate esters, alkyl phosphate esters, α-olefin sulfonates, alkanes. Examples thereof include sulfonates.
Examples of the cationic surfactant include alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, N-methylbishydroxyethylamine fatty acid ester hydrochloride and the like.
Examples of amphoteric surfactants include alkylamino fatty acid salts, alkylbetaines, and allylamine oxides.
Non-ionic surfactants include sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, fatty acid alkanolamide, polyoxyethylene alkyl ether, alkyl glycoside, polyoxyethylene alkyl phenyl ether, etc. Can be mentioned. These can be used alone or in combination.

Examples of the resin used for the microcapsule film include urethane resin, melamine resin, urea resin, epoxy resin, phenol resin, isocyanate resin, unsaturated polyester resin, polyimide resin, polyamide resin, acrylic resin, and nylon.
The particle size of the microcapsules is preferably 0.1 μm or more because of good handwriting erasability due to pressure such as rubbing. Below 0.1 μm, it is hard to break even if it is rubbed with the eraser, the resin of the writing instrument body, or the rubber-like elastic body. Also, the microcapsule penetrates between the fibers of the paper, and the pressure such as rub is not sufficiently transmitted and the microcapsule is broken. This is because it becomes difficult.
If the particle size of the microcapsule is 20 μm or more, the microcapsule is partially broken by the pen tip load (approximately 50 to 200 g) at the time of writing, the handwriting becomes thin, or the pen tip becomes clogged and the discharge amount is reduced. Becomes thinner. Considering the structure of the writing instrument, the particle size of the microcapsules is preferably 20 μm or less. The film thickness is preferably ¼ to 1/20 of the particle size. As a film material used for the film of the microcapsule, either a thermosetting resin or a thermoplastic resin can be selected. When the capsule film is a thermoplastic resin, the capsule film is broken by pressurization, and when the capsule film is a thermoplastic resin, the permeability of the capsule film is improved or broken by heating more than the glass transition.
When this microcapsule is used in a ballpoint pen, the ink composition passages in the ballpoint pen and the paper fibers are curved with irregularities on the top of several microns. Can move around. In addition, the microcapsule itself has a certain degree of elasticity, and it is difficult for extra pressure and friction to be applied due to the lubricating effect of the solvent. For this reason, it is difficult to apply a large force to the microcapsule, and it is unlikely to be crushed during writing. At the time of erasing, the liquid of the ink composition is rubbed several times on the handwriting that has penetrated into the paper at the eraser, the resin of the writing instrument body and the rubber-like elastic body, so the microcapsules collide and break down many times. , The decoloring agent contained in the skin exudes.

As the liquid medium used in the present invention, in addition to water, a hydrocarbon solvent or an aromatic alcohol that hardly interferes with the interaction with the leuco dye colored by the developer can be used.
Specific examples of hydrocarbon solvents include normal hexane, normal pentane, isohexane, normal heptane, normal octane, decane, dodecane, cyclohexane, methylcyclohexane, methylcyclopentane, ethylcyclohexane, aromatic alcohols such as benzyl alcohol, Examples thereof include phenethyl alcohol, phenyl glycol, 3-phenyl-1-propanol, 4-phenyl-2-butanol, and these can be used alone or in combination.
The amount used is preferably 50 to 90% by weight.

In addition, in order to make the ink composition for writing instruments, shear thinning imparting agent, pigment compound, resin dispersing agent and fixing agent for preventing sedimentation of microcapsules and preventing ink leakage from the nib and appropriate discharge amount, Lubricants, antiseptic / antifungal agents, rust preventives, antifoaming agents, dyes, pigments and the like for preventing wear of the ball seats can be appropriately contained. When a coloring component such as a dye or a pigment is added, the decoloring ink component is decolored from the mixed state at the time of color development and the handwriting is in a discolored state.
As the shear thinning agent, when the solvent is an aromatic alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl pyrrolidone, polyvinyl butyral and the like can be used.
When the solvent is a hydrocarbon solvent, fatty acid amide, oxidized polyolefin, hydrogenated castor oil, dry silica, bentonite and the like can be used.
When the solvent is water, gum arabic, gum tragacanth, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, casein, xanthene gum, dextran, welan gum, rhamzan gum, alka gum, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, starch glycol Sodium acid alginate, sodium alginate, propylene glycol alginate, hydroxypropylated guar gum, methylcellulose, ethylcellulose, polyvinylpyrrolidone, polyvinylmethylether, polyacrylic acid, carboxyvinyl polymer, polyethylene oxide, copolymer of vinyl acetate and polyvinylpyrrolidone, acrylic resin Salt, acrylic acid and alkyl methacrylate Copolymers or can use their salts, it can be used by mixing one or more of them.

When water is used as a solvent, antiseptic / antifungal agents include chloroacetamide, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl -4-isothiazoline-3-one, sodium dehydroacetate, sodium benzoate, sodium sorbate, potassium sorbate, thiabendazole, phenoxyethanol, sodium fluoride, 4- (2-nitrobutyl) morpholine, 1,3-dimorpholino-2- And ethyl-2-nitropropane, 2-bromo-2-nitropropane-1,3-diol, and the like.
Examples of the surface tension adjustment and antifoaming agent include silicon surfactants and fluorine surfactants.

A microcapsule is obtained by emulsifying a core material (substance included in a microcapsule) with a homogenizer, a high-pressure homogenizer, a magnetic stirrer, etc., and then forming a film using a magnetic stirrer or a three-one motor.
When making an ink, use an aromatic alcohol as a solvent, and when using a leuco dye or developer as a solvent, dissolve the leuco dye and developer with a magnetic stirrer or three-one motor, etc. Microcapsules can be added and dispersed with a roll mill, ball mill, sand grinder, attritor, homogenizer or the like.
When a hydrocarbon solvent or water is used as the solvent and the leuco dye and developer are finely divided, the fine particles of the leuco dye and developer and the microcapsules are roll mill, ball mill, sand grinder, atomizer. Can be dispersed with a lighter. The particle size is preferably about 0.1 to 10 μm.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and the like.

  As a method for producing a microcapsule, an in situ method or an interfacial polymerization method is known. The in situ method is a method in which an organic solvent (oil layer) containing a core substance is added to water (aqueous layer) and emulsified, and then a capsule film agent is added to polymerize the film on oil droplets. The interfacial polymerization method is a method in which a hydrophobic organic solvent (core substance) in which a capsule film agent is dissolved is emulsified in an aqueous layer, and then a reactant is added to form a film at the oil droplet interface.

Microcapsule 1 (in situ method)
(Water layer 1-1)
NIKKOL MYS-55V (polyethylene glycol monostearate, manufactured by Nikko Chemicals Co., Ltd.) 0.30 parts by weight Glycerin 2.00 parts by weight Water 17.70 parts by weight The above components are mixed and dissolved in a magnetic stirrer for 1 hour to obtain water. Layer 1-1 was obtained.
(Water layer 1-2)
Sumirez Resin 402K (35% solution of styrene maleic acid resin, manufactured by Taoka Chemical Co., Ltd.) 4.05 parts by weight Water 15.95 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to form an aqueous layer 1-2. Got.
(Oil layer 1)
Amyl acetate 10.00 parts by weight Hilac 110H (ketone resin, manufactured by Hitachi Chemical Co., Ltd.) 5.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an oil layer 1.
(Capsule film agent 1)
Becamine J300S (urea prepolymer, manufactured by DIC Corporation) 17.80 parts by weight resorcinol 2.20 parts by weight water 15.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain a capsule membrane 1 It was.
(Microcapsule adjustment)
The water layer 1-1 and the oil layer 1 are passed once by a homogenizer Star-Butst-Mini at a pressure of 80 MPa. This is added to the aqueous layer 1-2, and stirred at 13500 rpm for 10 minutes with a homogenizer. Thereafter, the pH was adjusted to 4.2, capsule membrane agent 1 was added, and the mixture was stirred with a magnetic stirrer for 4 hours to obtain a microcapsule dispersion having an average particle size of 3.0 μm. This was naturally dried to obtain a microcapsule 1 whose film material was urea resin.

Microcapsule 2 (interfacial polymerization method)
(Water layer 2-1)
NIKKOL MYS-55V (polyethylene glycol monostearate, manufactured by Nikko Chemicals Co., Ltd.) 0.20 parts by weight Urea 2.00 parts by weight Water 14.80 parts by weight The above components are mixed and dissolved in a magnetic stirrer for 1 hour to obtain water. Layer 2-1 was obtained.
(Water layer 2-2)
POVAL 117 (polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) 3.40 parts by weight of water 29.10 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an aqueous layer 2-2.
(Oil layer 2)
2-ethylhexyl acetate 14.00 parts by weight NIKKOL BS-2 (polyoxyethylene stearyl ether, manufactured by Nikko Chemicals Co., Ltd.) 1.00 parts by weight coronate HXLV (polyisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.)
2.00 weight part The said each component was mixed and melt | dissolved for 1 hour with the magnetic stirrer, and the oil layer 2 was obtained.
(Reactant 2)
Diethyltriamine 0.60 parts by weight Water 2.90 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain Reactant 2.
(Microcapsule adjustment)
The water layer 2-1 and the oil layer 2 are subjected to one pass at a pressure of 80 MPa with a homogenizer Star Burst Mini. This is added to the aqueous layer 2-2, and then added to the aqueous layer 2-2, followed by stirring with a homogenizer at 13500 rpm for 10 minutes. The reaction agent 2 was added there, and it stirred with the magnetic stirrer for 4 hours, and obtained the average particle diameter of 4 micrometer microcapsule dispersion liquid. This was naturally dried to obtain microcapsules whose film material was polyurethane.

Microcapsule 3 (in situ method)
(Water layer 3-1)
NIKKOL BC-30 (Polyoxyethylene Oleil Ether, manufactured by Nikko Chemicals Co., Ltd.) 0.30 parts by weight Glycerin 3.00 parts by weight Water 16.70 parts by weight The above components were mixed and dissolved in a magnetic stirrer for 1 hour. Layer 3-1 was obtained.
(Water layer 3-2)
ISOBAM-18 (isobutylene maleic resin, manufactured by Kuraray Co., Ltd.) 1.50 parts by weight of water 18.50 parts by weight The above components were heated and dissolved with sodium hydroxide to obtain aqueous layer 3-2.
(Oil layer 3)
Amyl acetate 10.50 parts by weight Hilac 110H (ketone resin, manufactured by Hitachi Chemical Co., Ltd.) 4.50 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain oil layer 3.
(Capsule film 3)
Becamine J300S (urea prepolymer, manufactured by DIC Corporation) 17.80 parts by weight Resorcinol 2.20 parts by weight Water 15.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain a capsule membrane 3 It was.
(Microcapsule adjustment)
The water layer 3-1 and the oil layer 3 are passed once by a homogenizer Star-Butst-Mini at a pressure of 80 MPa. This is added to the water layer 3-2 and stirred with a homogenizer at 13500 rpm for 10 minutes. Thereafter, the pH was adjusted to 4.2, the capsule membrane agent 3 was added, and the mixture was stirred with a magnetic stirrer for 4 hours to obtain a microcapsule dispersion having an average particle size of 3.0 μm. This was air-dried to obtain microcapsules 3 whose film material was urea resin.

Microcapsule 4 (in situ method)
(Water layer 4-1)
NIKKOL Decaglyn 1-50SV (polyglyceryl monostearate, manufactured by Nikko Chemicals Co., Ltd.) 0.30 parts by weight Glycerin 3.00 parts by weight Water 16.70 parts by weight The above components were mixed and dissolved in a magnetic stirrer for 1 hour. 4-1.
(Water layer 4-2)
Sumirez Resin 402K (35% solution of styrene maleic resin, Taoka Chemical Co., Ltd. 4.05 parts by weight water 15.95 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to form an aqueous layer 4-2. Obtained.
(Oil layer 4)
Amiacetate 9.50 parts by weight Hilac 110H (ketone resin, manufactured by Hitachi Chemical Co., Ltd.) 5.50 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain oil layer 4.
(Capsule film agent 4)
Becamine M-3 (melamine prepolymer, manufactured by DIC Corporation) 19.00 parts by weight Water 16.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain a capsule membrane 4.
(Microcapsule adjustment)
The water layer 4-1 and the oil layer 4 are passed by a homogenizer Star-Butst-Mini at a pressure of 80 MPa for one pass. This is added to the aqueous layer 4-2 and stirred at 13500 rpm for 10 minutes with a homogenizer. Thereafter, the pH was adjusted to 4.8, the capsule membrane agent 4 was added, and the mixture was stirred with a magnetic stirrer for 3 hours to obtain a microcapsule dispersion having an average particle size of 2.0 μm. This was air-dried to obtain microcapsules 4 whose film material was melamine resin.

Microcapsule 5 (in situ method)
(Water layer 5)
Sumirez Resin 402K (35% solution of styrene maleic resin, Taoka Chemical Co., Ltd. 4.20 parts by weight water 17.80 parts by weight glycerin 3.00 parts by weight The above components were mixed and dissolved for 1 hour with a magnetic stirrer. An aqueous layer 5 was obtained.
(Oil layer 5)
Diisononyl phthalate 9.00 parts by weight Triphenyl phosphate 6.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain oil layer 5.
(Film agent 5)
Becamine J300S (urea prepolymer, manufactured by DIC Corporation) 17.80 parts by weight resorcinol 2.20 parts by weight water 20.00 parts by weight Add the oil layer 5 to the water layer 5 and stir at 13500 rpm for 10 minutes with a homogenizer. . Thereafter, the pH was adjusted to 4.8, capsule membrane 5 was added, and the mixture was stirred with a magnetic stirrer for 3 hours to obtain a microcapsule dispersion having an average particle size of 4.0 μm. This was naturally dried to obtain microcapsules 5 whose film material was urea resin.

Microcapsule 6 (in situ method)
(Water layer 6-1)
Glycerin 5.00 parts by weight Water 12.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an aqueous layer 6-1.
(Water layer 6-2)
POVAL 117 (polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) 3.40 parts by weight water 29.10 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an aqueous layer 6-2.
(Oil layer 6)
Amyl acetate 14.00 parts by weight NIKKOL BS-2 (polyoxyethylene stearyl ether, manufactured by Nikko Chemicals Corporation) 1.00 parts by weight Coronate HXLV (polyisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.)
2.50 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an oil layer 2.
(Reactant 6)
Diethyltriamine 0.60 parts by weight Water 2.40 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain Reactant 6.
(Microcapsule adjustment)
The water layer 6-1 and the oil layer 6 are subjected to one pass at a pressure of 80 MPa using a homogenizer Star Burst Mini. This is added to the aqueous layer 6-2, and then added to the aqueous layer 6-2, and stirred at 13500 rpm for 10 minutes with a homogenizer. The reaction agent 6 was added there, and it stirred with the magnetic stirrer for 4 hours, and obtained the average particle diameter of 4 micrometer microcapsule dispersion liquid. This was naturally dried to obtain microcapsules whose film material was polyurethane.

Microcapsule 7 (in situ method)
(Water layer 7)
Ethylene glycol 5.00 parts by weight Water 15.00 parts by weight (oil layer 7)
2-ethylhexyl acetate 9.00 parts by weight Hilac 110H (ketone resin, manufactured by Hitachi Chemical Co., Ltd.) 6.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an oil layer 7.
(Capsule film agent 7)
Becamine J300S (urea prepolymer, manufactured by DIC Corporation) 17.80 parts by weight resorcinol 2.20 parts by weight water 15.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain a capsule membrane 7 It was.
(Microcapsule adjustment)
The oil layer 7 is added to the water layer 7 and stirred for 10 minutes at 13500 rpm with a homogenizer. Thereafter, the pH was adjusted to 4.2, the capsule membrane agent 7 was added, and the mixture was stirred with a magnetic stirrer for 3 hours to obtain a microcapsule dispersion having an average particle size of 5.0 μm. This was naturally dried to obtain microcapsules 7 whose film material was urea resin.

Microcapsule 8 (in situ method)
(Water layer 8)
Alkylbenzenesulfonate 1.40 parts by weight Water 18.60 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an aqueous layer 8.
(Oil layer 8)
9.50 parts by weight of amyl acetate Hilac 110H (ketone resin, manufactured by Hitachi Chemical Co., Ltd.) 5.50 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an oil layer 8.
(Capsule film 8)
Becamine J300S (urea prepolymer, manufactured by DIC Corporation) 17.80 parts by weight resorcinol 2.20 parts by weight water 15.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain a capsule membrane 8 It was.
(Microcapsule adjustment)
The oil layer 8 is added to the water layer 8 while stirring with a magnetic stirrer, and the mixture is stirred with a homogenizer at 13500 rpm for 10 minutes. The capsule film | membrane agent 8 was added there, and it stirred with the magnetic stirrer for 4 hours, and obtained the average particle diameter of 4 micrometer microcapsule dispersion liquid. This was naturally dried to obtain microcapsules 8 whose film material was urea resin.

(Base ink composition)
S-205 (black leuco dye, 2′-anilino-6 ′-(N-ethyl-N-isopentylamino) -3′-methylspiro [phthalide-3,9 ′ [9H] xanthene], Yamada Chemical Co., Ltd.
Product) 18.85 parts by weight Tamanol PA (phenol resin, manufactured by Arakawa Chemical Co., Ltd.) 17.65 parts by weight Bisphenol A 6.36 parts by weight Resorcin 12.61 parts by weight Benzyl alcohol 37.65 parts by weight PVP-K90 ( Polyvinyl pyrrolidone, manufactured by ISP Japan Co., Ltd.) 0.05 parts by weight ESREC BM-2 (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) 0.48 parts by weight MGO (glyceryl oleate, manufactured by Nikko Chemicals Co., Ltd.) 6 .36 parts by weight The above-mentioned components were stirred with a magnetic stirrer at 50 ° C. for 1 hour to obtain a stirring base ink composition.

Example 1
85 parts by weight of the base ink composition and 15 parts by weight of the microcapsules 1 were dispersed with a ball mill to obtain a black ink composition.

Example 2
82 parts by weight of the base ink composition and 18 parts by weight of the microcapsules 2 were dispersed and dispersed by a ball mill to obtain a black ink composition.

Example 3
83 parts by weight of the base ink composition and 17 parts by weight of the microcapsules 3 were dispersed and dispersed with a ball mill to obtain a black ink composition.

Example 4
83 parts by weight of the base ink composition and 17 parts by weight of the microcapsules 4 were dispersed and dispersed by a ball mill to obtain a black ink composition.

Example 5
86 parts by weight of the base ink composition and 14 parts by weight of the microcapsules 5 were dispersed and dispersed by a ball mill to obtain a black ink composition.

Example 6
80 parts by weight of the base ink composition and 20 parts by weight of the microcapsules 6 were dispersed and dispersed by a ball mill to obtain a black ink composition.

Example 7
80 parts by weight of the base ink composition and 20 parts by weight of the microcapsules 7 were dispersed and dispersed with a ball mill to obtain a black ink composition.

Comparative Example 1
80 parts by weight of the base ink composition and 20 parts by weight of the microcapsules 8 were dispersed and dispersed with a ball mill to obtain a black ink composition.

Comparative Example 2 (equivalent to Example 1 of JP-A-17-298746)
Thermochromic microcapsule pigment 9 (interfacial polymerization method)
(Thermochromic compound 9)
2- (2-Chloroanilino) -6-di-n-butylaminofluorane (black leuco dye)
4.50 parts by weight 1,1-bis (4′-hydroxyphenyl) n-decane (developer) 4.50 parts by weight 1,1-bis (4′-hydroxyphenyl) hexafluoropropane (developer)
7.50 parts by weight 4-benzyloxyphenylethyl caprate (decolorant) 50.00 parts by weight The above components were stirred with a magnetic stirrer at 50 ° C. for 1 hour to obtain thermochromic compound 9.
(Water layer 9)
Water 92.00 parts by weight POVAL 117 (polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) 8.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain an aqueous layer material 9.
(Oil layer (core substance, capsule membrane agent) 9)
Thermochromic compound 9 70.00 parts by weight Cosmonate T-80 (tolylene diisocyanate, manufactured by Mitsui Chemicals, Inc.)
30.00 parts by weight (reactant 9)
Water 85.00 parts by weight Diethyltriamine 15.00 parts by weight The above components were mixed and dissolved with a magnetic stirrer for 1 hour to obtain a polyvalent amine compound 8.
(Microencapsulation)
48.4 parts by weight of the water layer 9 and 42.0 parts by weight of the oil layer (core substance) 9 are emulsified with a homogenizer at 40 ° C. for 1 hour. 9.6 parts by weight of the reactant 9 was added thereto, and further stirred with a homogenizer for 2 hours to obtain a microcapsule dispersion, which was dried to obtain thermochromic microcapsules 9.
(Ink)
Microcapsule 9 25.70 parts by weight succinoglucan (shear thinning agent, manufactured by Sanki Co., Ltd.) 0.20 parts by weight urea 5.50 parts by weight glycerin 7.50 parts by weight Nopco SW-WET-366 (penetration) 0.03 parts by weight FS Antifoam 013B (antifoaming agent, manufactured by Nippon Silicone Co., Ltd.) 0.15 parts by weight Proxel XL-2 (preservative, manufactured by Geneca Co., Ltd.) 0.10 parts by weight Plysurf A212C (lubricant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.50 parts by weight Triethanolamine 0.50 parts by weight Water 59.82 parts by weight The above components except for succinoglucan are misrolled After dispersion, add succinoglucan and stir with a magnetic stirrer for 2 hours. Then, it was left to stand at −20 ° C. for 24 hours to obtain a black ink composition.

Concentration measurement The ink composition obtained in each of the above Examples and Comparative Examples was filled in an aqueous gel ballpoint pen BLN25 (product name Energel, ball diameter 0.5 mm, manufactured by Pentel Co., Ltd.), and high quality paper (JIS P3201 writing paper). In A), a straight line of 5 cm was juxtaposed within a width of 1.5 cm and written between the straight lines without any gap, and after left for 1 hour and left for 1 month, the Y value of the writing surface was measured with a color computer. The Y value of fine paper was 83.4%.

In Examples 1 to 7, due to the use of one or a mixture of two or more selected from water-soluble polymers, sugars, sugar alcohols, and urea compounds, a decrease in handwriting concentration due to leakage of the erasing agent was hardly observed. In Examples 1 to 4, a reduction in handwriting concentration was not observed due to the use of a surfactant that was substantially insoluble in polar compounds.
On the other hand, Comparative Example 1 uses a compound having one or more hydrophilic groups selected from a hydroxyl group, a carbonyl group, an amino group, and a polyoxyalkylene group, which is a room temperature solid or a room temperature liquid having a boiling point of 150 ° C. or higher. However, after writing, the handwriting density began to decrease, and the handwriting one month after writing was almost erased. Moreover, in the comparative example 2, since the heat erasable microcapsule was used, handwriting density was not favorable compared with Examples 1-7.

Claims (3)

It consists of a leuco dye, a developer, a liquid medium, and a microcapsule enclosing a polar compound. An ink composition in which a compound having one or more hydrophilic groups selected from a hydroxyl group, a carbonyl group, an amino group, and a polyoxyalkylene group is disposed in a layered manner. The ink according to claim 1, wherein the compound disposed between the capsule membrane material and the polar substance is one or a mixture of two or more selected from water-soluble polymers, sugars, sugar alcohols, and urea compounds. Composition. The ink composition according to claim 1, wherein the compound disposed between the capsule film material and the polar substance contains a surfactant that is substantially insoluble in the polar compound.