JP4423102B2 - Marking pen - Google Patents

Description

The present invention relates to a marking pen containing a reversible thermochromic writing oil-based ink composition.

Conventionally, (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound (c) a compound that is a reaction medium that reversibly causes the electron-donating reaction by (a) and (b) above. A writing instrument filled with an ink composition for a writing instrument in which a microcapsule pigment encapsulating a reversible thermochromic composition is dispersed in an aqueous medium is disclosed (for example, see Patent Document 1).
When the writing instrument is written on a porous material such as paper, a good handwriting that reversibly changes color due to temperature change is obtained, but when writing on a non-absorbing surface such as glass or plastic, the handwriting is sufficient. Even if it did not transfer, or even if it was able to form a handwriting, it was inferior in drying property, so it was forced to dry for a long time, and it was difficult to satisfy practicality.
JP-A-1-54081

The present invention relates to a marking pen that can form a good handwriting on any writing surface, and has a reversible thermochromic writing oil-based ink composition that is excellent in drying properties and convenience.

The present invention comprises (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a homogeneous solution of a reaction medium that controls the color reaction of (a) and (b). The microcapsule pigment containing the reversible thermochromic composition and at least an organic solvent, the average particle diameter of the microcapsule pigment contained in the ink is 1 to 10 μm, and the microcapsule pigment is less than 1.0 μm. A marking pen containing a reversible thermochromic writing oil-based ink composition containing 10% by weight or less in the capsule pigment and 10% by weight or less in the microcapsule pigment is required.
Further, the organic capsule having a weight ratio of the reversible thermochromic composition of the microcapsule pigment to the wall film in the range of 5/1 to 1/1, and an organic solvent having a vapor pressure at 20 ° C. of 5.0 to 50 mmHg is mainly used. The requirement is to use it as a solvent.

  The ink composition of the present invention can form clear handwriting on any writing surface, and since the handwriting has excellent drying properties, the utility of the recorded matter in which the handwriting is formed by the ink composition can be improved. A reversible thermochromic oil-based ink composition for writing excellent in convenience satisfying applicability to the temperature indicating field and the decoration field can be provided.

The reversible thermochromic microcapsule pigment is a conventionally known (a) electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction that determines the temperature at which the color reaction of both occurs. A reversible thermochromic composition containing three essential components of a medium is encapsulated in a microcapsule, and the heat-decolorable microcapsule pigment that is decolored by heating from a colored state is a special feature proposed by the present applicant. Those described in JP-B-51-44706, JP-B-51-44707, JP-B-1-29398 and the like are used.
As shown in the temperature-color density curve of FIG. 1, the pigment discolors before and after a predetermined temperature (discoloration point) and exhibits a decolored state in a temperature range higher than the high temperature side complete discoloration temperature (t ₄ ). It exhibits a colored state in a temperature range below the low-temperature side complete discoloration temperature (t ₁ ), and only one specific state exists in the normal temperature range among the two states. That is, the other state is maintained while the heat or cold necessary to develop the state is applied, but when the heat or cold is not applied, the state returns to the state exhibited in the normal temperature range. The width is relatively small.
Further, as a heat-erasable type microcapsule pigment, those disclosed in Japanese Patent Publication No. 4-17154, Japanese Patent Application Laid-Open No. 7-179777, Japanese Patent Application Laid-Open No. 7-33997, Japanese Patent Application Laid-Open No. 8-39936, etc. proposed by the present applicant. Those described can also be used.
The pigment exhibits a large hysteresis characteristic, and the shape of the curve in which the change in color density due to temperature change is plotted increases the temperature from the lower temperature side than the color change temperature range, and conversely from the higher temperature side than the color change temperature range. The color changes by following a path that is largely different from that when the color is lowered, and the color changes in the low temperature region below the low temperature side complete discoloration temperature (t ₁ ) or in the high temperature region above the high temperature side complete discoloration temperature (t ₄ ). The decolored state can be stored and held interchangeably in a specific temperature range [temperature range between t _{42 and} t ₃ (substantially two-phase holding temperature range)] (see FIG. 2).
Further, as an electron-accepting compound proposed by the present applicant that develops color by heating from a decolored state as a heat-colorable microcapsule pigment, and decolorizes by a temperature drop, A system to which a specific alkoxyphenol compound having a side chain alkyl group is applied (Japanese Patent Laid-Open Nos. 11-129623 and 11-5973), a system to which a specific hydroxybenzoic acid ester is applied (Japanese Patent Laid-Open No. 2001-105732) In addition, a system to which a specific gallic acid ester or the like is applied (Japanese Patent Laid-Open No. 2003-253149) can also be used (see FIG. 3).

The microcapsule pigment applied to the present invention does not refuse application in the form of a circular cross section, but is effective in the form of a non-circular cross section.
The microcapsule pigment with the non-circular cross-sectional shape is slightly elastically deformed into a shape that relaxes the external force against the application of external force, and the destruction of the wall film of the microcapsule pigment is suppressed, and it is effective without impairing the thermal discoloration function. Can be expressed.
Each of the above components may be a mixture of two or more, and an antioxidant, an ultraviolet absorber, an infrared absorber, a dissolution aid and the like can be added as long as the function is not hindered.
The three-component homogeneous compatible mixture is used by being encapsulated in microcapsules. This is because, even when contacted with a chemically active substance such as an acidic substance, a basic substance, or a peroxide, or a solvent component, its function is not deteriorated, and heat resistance stability can be maintained. This is because the reversible thermochromic composition is maintained in the same composition under various use conditions and can exhibit the same effects.
The microcapsules satisfy practicality in the range of an average particle size of 1.0 to 10 μm, preferably 1.0 to 5 μm.
In the system where the average value of the maximum outer diameter exceeds 10 μm, the microcapsule lacks dispersion stability for use in ink.
On the other hand, in a system having an average value of the maximum outer diameter of 1.0 μm or less, it is difficult to exhibit high density color development.
The microcapsule pigment contains inclusions / wall film = 5/1 to 1/1 (weight ratio), preferably 4/1 to 1/1 (weight ratio), more preferably 3/1 to 1/1. The range of (weight ratio) is effective, and when the weight ratio of the inclusion is larger than the above ratio, the solvent resistance of the wall film is poor, and when the weight ratio of the wall film is larger than the above ratio, a sufficient color at the time of color development. It becomes difficult to express the concentration.
The microencapsulation includes conventionally known isocyanate-based interfacial polymerization methods, in-situ polymerization methods such as melamine-formalin, in-liquid curing coating methods, phase separation methods from aqueous solutions, phase separation methods from organic solvents, melting There are a dispersion cooling method, an air suspension coating method, a spray drying method, and the like, which are appropriately selected according to use. Further, a secondary resin film may be provided on the surface of the microcapsule according to the purpose to impart durability, or the surface characteristics may be modified for practical use.
The microcapsule pigment or an ink composition using the microcapsule pigment can be mixed with a general dye or pigment to exhibit a color change behavior from colored (1) to colored (2).

The ink composition of the present invention is obtained by dispersing a microcapsule pigment as a colorant in an organic solvent.
Conventional organic solvents can be used as the organic solvent, and are used in the range of 40 to 80% by weight in the ink composition.
Examples of the organic solvent include benzyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, benzyl glycol, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monoethyl ether, diethylene glycol monophenyl ether, propylene glycol mono Ethyl ether, propylene glycol monophenyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monophenyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monophenyl ether, methyl lactate, ethyl lactate, γ -Butyrolac The emissions and the like.

Moreover, when the solvent whose vapor pressure in 20 degreeC which is easy to volatilize as an organic solvent is 5.0-50 mmHg is used as a main solvent, it is excellent in the drying property of handwriting.
Examples of the organic solvent having a vapor pressure of 5.0 to 50 mmHg (20 ° C.) include ethyl alcohol (45), n-propyl alcohol (14.5), isopropyl alcohol (32.4), and n-butyl alcohol (5.5). ), Alcohol organic solvents such as isobutyl alcohol (8.9), sec-butyl alcohol (12.7), tert-butyl alcohol (30.6), tert-amyl alcohol (13.0),
Glycol ether organic solvents such as ethylene glycol monomethyl ether (8.5), ethylene glycol diethyl ether (9.7), ethylene glycol monoisopropyl ether (6.0), propylene glycol monomethyl ether (7.6),
n-heptane (35.0), n-octane (11.0), isooctane (41.0), methylcyclohexane (37.0), ethylcyclohexane (10.0), toluene (24.0), xylene ( 5.0-6.0), hydrocarbon organic solvents such as ethylbenzene (7.1),
Ketone organic solvents such as methyl isobutyl ketone (16.0), methyl n-propyl ketone (12.0), methyl n-butyl ketone (12.0), di-n-propyl ketone (5.2),
N-butyl formate (22.0), isobutyl formate (33.0), n-propyl acetate (25.0), isopropyl acetate (48.0), n-butyl acetate (8.4), isobutyl acetate (13 0.0), ethyl propionate (28.0), n-butyl propionate (45.0), methyl butyrate (25.0), ethyl butyrate (11.0), and other organic organic solvents.
The numbers in parentheses indicate the vapor pressure of each organic solvent at 20 ° C.
Further, a small amount of water can be added within the range that does not impair the drying property.

  If necessary, as a resin, ketone resin, ketone-formaldehyde resin, amide resin, alkyd resin, rosin modified resin, rosin modified phenol resin, phenol resin, xylene resin, polyvinyl pyrrolidone, α- and β-pinene / phenol polycondensation resin, polyvinyl A butyral resin, an acrylic resin, a styrene maleic acid copolymer, a cellulose derivative, polyvinyl pyrrolidone, polyvinyl alcohol, dextrin and the like can also be used, and can be used for fixing to a paper surface or imparting viscosity.

Further, if necessary, a shear thinning agent can be added.
By adding the shear thinning agent, the aggregation and sedimentation of the microcapsule pigment can be suppressed, and the bleeding of the handwriting can be suppressed.
Furthermore, when the writing instrument to be filled with the ink is in the form of a ballpoint pen, it prevents ink leakage from the gap between the ball and the tip when not in use, or the ink when the writing tip is left upward (upright state). Backflow can be prevented.

Examples of the shear thinning agent include cross-linked acrylic resins, cross-linked acrylic resin emulsion types, non-cross-linked acrylic resins, cross-linked N-vinylcarboxylic acid amide polymers or copolymers, and non-cross-linked N-vinyl carvone. Acid amide polymer or copolymer, hydrogenated castor oil, fatty acid amide wax, wax such as oxidized polyethylene wax, stearic acid, palmitic acid, octylic acid, fatty acid metal salt such as aluminum salt of lauric acid, dibenzylidene sorbitol, Examples thereof include N-acylamino acid compounds, smectite inorganic compounds, montmorillonite inorganic compounds, bentonite inorganic compounds, hectorite inorganic compounds, and silica.
The shear thinning agent can be used in combination, and the polymer can be used as a resin.

  When the ink composition of the present invention is used by filling a ballpoint pen, a higher fatty acid such as oleic acid, a nonionic surfactant having a long chain alkyl group, a polyether-modified silicone oil, a thiophosphorous acid tri (alkoxycarbonylmethyl ester) ) And thiophosphite triester (alkoxycarbonylethyl ester), etc., polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphate monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether It is preferable to add a lubricant such as a phosphoric acid diester or a metal salt, an ammonium salt, an amine salt, an alkanolamine salt thereof to give the ball seat an antiwear effect.

The average particle diameter of the microcapsule pigment contained in the ink is 1 to 10 μm, the microcapsule pigment less than 1 μm is 10% by weight or less, and the microcapsule pigment exceeding 10 μm is 10% by weight or less. Is preferred.
More preferably, the average particle diameter of the microcapsule pigment is 1 to 5 μm, the microcapsule pigment having a particle size of less than 1.0 μm is 10% by weight or less, and the microcapsule pigment having a particle size exceeding 5 μm is 5% by weight or less.
If the microcapsule pigment of less than 1 μm is contained in an amount exceeding 10% by weight, the microcapsule is liable to be deteriorated by the solvent, so that the discoloration function is impaired and the handwriting does not easily develop a sufficient color density.
If the microcapsule pigment exceeding 10 μm is contained in an amount exceeding 10% by weight, clogging occurs at the writing tip of the writing instrument filled with the ink, making it difficult for the ink to come out, and the handwriting is blurred, It becomes easy to produce the malfunction which does not come out.

It said ink composition is subjected to practical use by filling the marking pen equipped with a tip to the writing tip.
When filling the marking pen, the structure and shape of the marking pen itself are not particularly limited. For example, a fiber tip, felt tip, plastic tip is attached to the writing tip, and the fiber bundle contained in the shaft cylinder is used. The ink occlusion body is impregnated with ink, the ink is supplied to the tip of the writing, the ink is directly stored inside the shaft cylinder, and the ink flow rate adjustment member consisting of a comb groove-like ink flow rate adjustment member or fiber bundle is interposed Examples include a marking pen having a structure in which ink is directly stored in the shaft cylinder and a predetermined amount of ink is supplied to the writing tip portion by a valve mechanism.

For example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon is used as the ink storage tube that stores the ink composition.
Furthermore, by using a transparent, colored transparent, or translucent molded body as the ink containing tube, the ink color, the remaining amount of ink, and the like can be confirmed.
In addition to directly connecting the chip to the ink storage tube, the ink storage tube and the chip may be connected via a connecting member.
The ink storage tube may be a refill type in which the refill is accommodated in the shaft cylinder, or the shaft cylinder itself having a tip mounted on the tip is used as an ink container to directly fill the shaft cylinder with ink. May be.

The back end of the ink composition accommodated in the ink accommodating tube may be filled with an ink backflow prevention body.
The ink backflow prevention body composition is composed of a non-volatile liquid or a hardly volatile liquid.
Specifically, petroleum jelly, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, Examples thereof include polyether-modified silicone oil and fatty acid-modified silicone oil, and one or more can be used in combination.

It is preferable to add a gelling agent to the nonvolatile liquid and / or the hardly volatile liquid to increase the viscosity to a suitable viscosity. The surface of the silica is hydrophobized, the surface is methylated fine particle silica, and aluminum silicate. , Swellable mica, hydrophobic thickeners such as bentonite and montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, zinc stearate, tribenzylidene sorbitol, fatty acid amide, amide modified Examples include dextrin compounds such as polyethylene wax, hydrogenated castor oil, fatty acid dextrin, and cellulose compounds.
Furthermore, the liquid ink backflow prevention body composition and a solid ink backflow prevention body composition can be used in combination.
Incidentally, the form of pre-KOR Kingupen is not limited to those described above, different or the pen body is mounted in the form, it may be a writing instrument different twin type color tone of the pen body to derive the ink is attached .

Examples of the present invention are shown below, but the present invention is not limited thereto.
Example 1
Preparation of reversible thermochromic microcapsule pigment (a) 2- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide 2.5 as component Parts by weight, 4.0 parts by weight of 2,2-bis (4-hydroxyphenyl) hexafluoropropane as component (b), 8.0 parts by weight of 1,1-bis (4-hydroxyphenyl) n-octane, ) A reversible thermochromic composition comprising 50.0 parts by weight of neopentyl stearate as a component is uniformly heated and dissolved, and 30.0 parts by weight of an aromatic polyisocyanate prepolymer as a wall film material, 40.0 parts by weight of a co-solvent The mixture of the components was emulsified and dispersed in an 8% aqueous polyvinyl alcohol solution so that the average particle size was 3 μm, and the mixture was stirred at 70 ° C. for about 1 hour. Amine 2.5 parts by weight was added to obtain a reversible thermochromic microcapsule pigment suspension and stirring was further continued for 6 hours.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The weight ratio of the reversible thermochromic composition of the microcapsule pigment to the wall film is 2.15 / 1, the average particle size is 2.6 μm, and the weight less than 1.0 μm is 1% in the microcapsule pigment. %, Exceeding 10 μm was 2% by weight in the microcapsule pigment.
The microcapsule pigment is blue at 5 ° C. or lower and colorless at 32 ° C. or higher, and can selectively retain color in the temperature range therebetween.

Preparation of reversible thermochromic oil-based ink composition for writing 12.0 parts by weight of the above microcapsule pigment (dried product), alkyd resin [trade name: Arachid 5301X-50, manufactured by Arakawa Chemical Co., Ltd.] 10.0 parts by weight A reversible thermochromic oil-based ink composition for writing consisting of 78 parts by weight of xylene was prepared.

Manufacture of writing instruments The ink (previously cooled to 5 ° C or lower) is impregnated with 2.0 g of a fiber-gathered ink occlusion body (porosity of about 80%) covered with a synthetic resin film on a polyester sliver and stored in the shaft cylinder. Then, a chisel type fiber pen body (porosity of about 50%) was attached to the tip of the shaft tube to obtain a marking pen.
The marking pen is provided with a detachable cap.
The handwriting obtained by writing on the glass surface using the marking pen could form clear handwriting without repelling on the glass surface.
Furthermore, since the handwriting is excellent in drying property, even if it is rubbed with a finger, the handwriting is transferred to a blank part and no stain is generated, and a good blue handwriting can be formed, and the state is in a temperature range of less than 32 ° C. Was retained.
When the handwriting was heated to 32 ° C. or higher, the handwriting was decolored and colorless, and the state was maintained in a temperature range of 5 ° C. or higher.
When the temperature was again cooled to 5 ° C. or lower, the color changed to blue, and this mode change could be repeated.

Example 2
Preparation of reversible thermochromic microcapsule pigment (i) 4.0 parts by weight of 6- (ethylisobutylamino) benzofluorane as component, (b) 2,2-bis (4-hydroxyphenyl) hexafluoropropane 4 as component A reversible thermochromic composition comprising 0.0 parts by weight, 1,1-bis (4-hydroxyphenyl) n-octane, 8.0 parts by weight, and (5) parts of neopentyl stearate as component (c) is uniformly added. A solution in which 30.0 parts by weight of an aromatic polyvalent isocyanate prepolymer and 40.0 parts by weight of a co-solvent are mixed as a wall film material in a 8% polyvinyl alcohol aqueous solution so as to have an average particle diameter of 3 μm is dissolved by heating. After emulsification and dispersion, stirring was continued at 70 ° C. for about 1 hour, 2.5 parts by weight of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to reversible thermochromic microcatalysis. To obtain a cell pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The weight ratio of the reversible thermochromic composition of the microcapsule pigment to the wall film is 2.2 / 1, the average particle size is 2.3 μm, and the weight of less than 1.0 μm is 4% in the microcapsule pigment. %, Exceeding 10 μm was 1% by weight in the microcapsule pigment.
The microcapsule pigment exhibits a magenta color at 5 ° C. or lower, and colorless at 32 ° C. or higher, and can selectively retain the color in the temperature range therebetween.

Preparation of reversible thermochromic oil-based ink composition for writing 12.0 parts by weight of the above microcapsule pigment (dried product), phenol resin [trade name: Tamanol PA, Arakawa Chemical Industries, Ltd.] 10.0 parts by weight, isopropyl A reversible thermochromic oil-based ink composition for writing consisting of 13.0 parts by weight of alcohol and 68.0 parts by weight of propylene glycol monomethyl ether was prepared.

Manufacture of writing instruments The ink (previously cooled to 5 ° C or lower) is impregnated with 2.0 g of a fiber-gathered ink occlusion body (porosity of about 80%) covered with a synthetic resin film on a polyester sliver and stored in the shaft cylinder. Then, a chisel type fiber pen body (porosity of about 50%) was attached to the tip of the shaft tube to obtain a marking pen.
The marking pen is provided with a detachable cap.
The handwriting obtained by writing on the surface of the plastic film using the marking pen was able to form a clear handwriting without repelling on the film surface.
Furthermore, since the handwriting is excellent in drying property, even if it is rubbed with a finger, the handwriting does not move to a blank part and stains can be formed, and a good magenta handwriting can be formed. The state has been retained.
When the handwriting was heated to 32 ° C. or higher, the handwriting was decolored and colorless, and the state was maintained in a temperature range of 5 ° C. or higher.
When the temperature was again cooled to 5 ° C. or lower, the color changed to magenta, and this aspect change could be repeated.

Example 3
Preparation of reversible thermochromic microcapsule pigment (i) 4.0 parts by weight of 6- (ethylisobutylamino) benzofluorane as component, (b) 2,2-bis (4-hydroxyphenyl) hexafluoropropane 4 as component 0.0 parts by weight, 1,1-bis (4-hydroxyphenyl) n-octane 8.0 parts by weight, (c) as component 20.0 parts by weight n-butyl palmitate, 30.0 parts by weight n-butyl stearate A reversible thermochromic composition consisting of parts is uniformly heated and dissolved, and a solution prepared by mixing 30.0 parts by weight of an aromatic polyvalent isocyanate prepolymer and 40.0 parts by weight of a co-solvent as a wall film material is mixed with 8% polyvinyl. The mixture was emulsified and dispersed in an aqueous alcohol solution so that the average particle size became 3 μm, and stirred at 70 ° C. for about 1 hour. Then, 2.5 parts by weight of a water-soluble aliphatic modified amine was added, and another 6 hours To obtain a reversible thermochromic microcapsule pigment suspension continued stirring.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The weight ratio of the reversible thermochromic composition of the microcapsule pigment to the wall film is 1.65 / 1, the average particle size is 3 μm, and the weight ratio of less than 1.0 μm is 1% by weight in the microcapsule pigment, The amount exceeding 10 μm was 4% by weight in the microcapsule pigment.
The microcapsule pigment exhibits a magenta color at 12 ° C. or lower, and colorless at 18 ° C. or higher.

Preparation of reversible thermochromic oil-based ink composition for writing 15.0 parts by weight of the above microcapsule pigment (dried product), α, β-pinene / phenol polycondensate (trade name: YS Polystar S145, manufactured by Yasuhara Chemical Co., Ltd.) Reversible heat consisting of 5.0 parts by weight, polyoxyethylene alkyl ether phosphate ester (trade name: Prisurf A207H, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 75.0 parts by weight of propylene glycol monomethyl ether A discolorable writing oil-based ink composition was prepared.

Preparation of writing instrument 0.97 g of the ink was sucked and filled into a polypropylene pipe having an inner diameter of 4.4 mm, and connected to a ballpoint pen tip through a resin holder.
Next, from the rear part of the polypropylene pipe, an ink backflow prevention body (liquid stopper) having viscoelasticity mainly composed of polybutene is filled, and a tail plug is fitted to the rear part of the pipe. After the cylinder was assembled and the cap was fitted, a deaeration process was performed by a centrifugal process to obtain a ballpoint pen.
The ball-point pen tip has a stainless steel ball having a diameter of 0.7 mm held at the tip end of a tip formed by pressing and deforming the vicinity of the tip of a metal pipe inward from the outer surface, and the ball is a spring. It is energized forward by the body.
The handwriting obtained by writing on the metal surface using the ballpoint pen could form a clear handwriting without cissing on the metal surface.
Further, since the handwriting was excellent in drying property, even if it was rubbed with a finger, the handwriting was transferred to a blank portion and no stain was produced, and a good magenta handwriting could be formed.
When the handwriting was heated to 18 ° C. or higher, the color disappeared and became colorless, and when it was cooled again to 12 ° C. or lower, it changed to magenta, and this change in appearance could be repeated.

It is explanatory drawing of the temperature-color density curve of the heat decoloring type microcapsule pigment applied to this invention. It is explanatory drawing of the temperature-color density curve of the heat-erasable type microcapsule pigment (color memory retention type) applied to this invention. It is explanatory drawing of the temperature-color density curve of the heat coloring type | mold microcapsule pigment applied to this invention.

ΔH _A Hysteresis temperature range (heat decoloring type)
ΔH _B hysteresis temperature range (heat decoloration-color memory retention type)
[Delta] H _C hysteresis temperature range (heat-coloring type)
t ₁ Low temperature side complete discoloration temperature of the heat decolorable microcapsule pigment t ₂ Low temperature side discoloration start temperature of the heat decolorable microcapsule pigment t ₃ High temperature side discoloration start temperature of the heat decolorable microcapsule pigment t ₄ Heat decoloration High temperature side complete discoloration temperature of the type ₁ microcapsule pigment T ₁ low temperature side complete discoloration temperature of the heating type microcapsule pigment T ₂ low temperature side discoloration start temperature of the ₂ heating color development type microcapsule pigment T ₃ high temperature side discoloration of the heating type color microcapsule pigment Starting temperature T ₄ Complete color change temperature on the high temperature side of the heat-generating color microcapsule pigment

Claims (3)

(B) Reversible thermochromic property comprising a homogeneous solution of a reaction medium that controls the color reaction of (a) and (b) above. The microcapsule pigment including the composition and at least an organic solvent, the average particle diameter of the microcapsule pigment contained in the ink is 1 to 10 μm, and the microcapsule pigment is less than 1.0 μm in the microcapsule pigment A marking pen comprising a reversibly thermochromic writing oil-based ink composition containing 10% by weight or less and 10% by weight or more in a microcapsule pigment . The marking pen according to claim 1, wherein the weight ratio of the reversible thermochromic composition of the microcapsule pigment to the wall film is in the range of 5/1 to 1/1 . The marking pen according to claim 1, wherein an organic solvent having a vapor pressure at 20 ° C of 5.0 to 50 mmHg is used as a main solvent .

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