JP2012021051A - Reversible thermochromic water-based ink composition, writing utensil using the same, and writing utensil set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible thermochromic water-based ink composition capable of suppressing light colorization and dark colorization of handwriting and exhibiting sufficient handwriting fixing property even if writing is performed on a writing surface where an ink is hardly permeated, a writing utensil using it and a writing utensil set.SOLUTION: The reversible thermochromic water-based ink composition comprises water, a reversible thermochromic micro-capsule pigment in which a reversible thermochromic composition comprising (a) an electron-donative coloring organic compound, (b) an electron-accepting compound and (c) a reaction medium for determining a generation temperature of a coloring reaction of both compounds is incorporated, a polymer flocculant, a comb-like polymeric dispersant having a carboxyl group in a side chain, an organic nitrogen sulfur compound, a dispersion stabilizer, and a polyurethane emulsion or acrylic resin emulsion having pH of 5-9. The pH of the ink composition is in a range of 5-8. The writing utensil 1 uses the ink composition. The writing utensil set comprises the writing utensil and a friction body.

Description

  The present invention relates to a reversible thermochromic water-based ink composition, a writing instrument using the same, and a writing instrument set.

Conventionally, a reversible thermochromic water-based ink capable of forming a handwriting whose color tone changes with temperature change and a writing instrument filled with the ink have been disclosed (for example, see Patent Document 1).
The ink contained in the writing instrument is such that the reversible thermochromic capsule pigment gradually aggregates and settles in the ink occlusion due to the specific gravity difference between the reversible thermochromic microcapsule pigment and the vehicle, or the pen body faces downward (inverted state), or The problem is that the handwriting is lightened or darkened depending on the upward (upright state) state, and the ink is mixed with a water-soluble polymer flocculant, and the polymer flocculant has a loose bridge. The above problem is solved by suspending the microcapsule pigment in a loosely aggregated state by the bridging action.
However, blending of the polymer flocculant can suppress the aggregation and sedimentation of the microcapsule pigment for a short period of time, but the lightening and darkening of the handwriting due to the specific gravity difference between the microcapsule pigment and the vehicle can be prevented for a long time. It is difficult to suppress completely, and in some cases, the handwriting is lightened with time in an upright state, or the handwriting is lightened by applying vibration during transportation or carrying in an upright state.
In addition, the so-called aging test that is allowed to stand at 50 ° C., room temperature, and 0 ° C. does not cause a problem in writing performance, but is left in a temperature range below 0 ° C. where the ink freezes or the ink is frozen. In the case where the ink that changes color in the temperature range to be used is put into practical use, the ink outflow property may be impaired in the process of thawing the frozen ink again.
In order to solve the above problems, the ink composition contains a comb-type polymer dispersant having a carboxyl group in the side chain, an organic nitrogen sulfur compound, and a water-soluble resin, and the pH of the ink is 3 to 7. Although it is disclosed to adjust to the range (see, for example, Patent Document 2), the ink described in the Patent Document is required when writing on the surface where the ink such as a resin film or coated paper is difficult to penetrate. The handwriting fixability was not sufficient, and the handwriting was easily peeled off by rubbing.

JP-A-11-335613 JP 2009-227954 A

  The present invention can suppress lightening and darkening of the handwriting of the reversible thermochromic water-based ink composition, and in particular, the handwriting is lightened over time in an upright state, or the handwriting is applied by vibration during transportation or carrying. A reversible thermochromic water-based ink composition that exhibits good writing performance without causing light coloration, and can exhibit sufficient handwriting fixability even when writing on a resin film, coated paper, or other ink-resistant surface An object, a writing instrument using the same, and a writing instrument set are provided.

The present invention relates to a reversible thermochromic composition comprising water and (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction occurs. A reversible thermochromic microcapsule pigment encapsulating a product, a polymer flocculant, a comb-type polymer dispersant having a carboxyl group in a side chain, an organic nitrogen sulfur compound, a dispersion stabilizer, and a pH of 5 A reversible thermochromic water-based ink composition comprising a polyurethane emulsion or an acrylic resin emulsion of 9 to 9 and having a pH of 5 to 8 in the ink composition is a requirement.
Further, the organic nitrogen sulfur compound is 2- (4-thiazoyl) -benzimidazole, 2- (thiocyanatomethylthio) -1,3-benzothiazole, 2-methyl-4-isothiazolin-3-one, 5-chloro- It is a compound selected from 2-methyl-4-isothiazolin-3-one, and the mass ratio of the comb-type polymer dispersant having a carboxyl group in the side chain and the organic nitrogen sulfur compound is 1: 1 to 1:10. And the use of a water-soluble resin soluble in the pH range of 5 to 8 as the dispersion stabilizer.
Furthermore, the writing instrument provided with the pen body which accommodates the said reversible thermochromic water-based ink composition in a shaft cylinder, and guide | leads out the ink composition in the said shaft cylinder is made into requirements.
Furthermore, it is a requirement that the pen body is a marking pen body, a friction member is provided, and the like.
Furthermore, a writing instrument set including the writing instrument and a friction body is a requirement.

  The present invention can suppress the lightening and darkening of the handwriting, and in particular, the handwriting does not lighten over time in an upright state or the handwriting does not lighten by applying vibration during transportation or carrying. It is possible to provide a reversible thermochromic water-based ink composition that exhibits writing performance and exhibits sufficient handwriting fixability even when writing on a writing surface that is difficult for ink to penetrate, and a writing tool and a writing tool set using the same.

It is explanatory drawing which shows the discoloration behavior of a heat decoloring type reversible thermochromic microcapsule pigment. It is explanatory drawing which shows the discoloration behavior of the heat decoloring type reversible thermochromic microcapsule pigment having color memory. It is explanatory drawing which shows the discoloration behavior of a heat coloring type reversible thermochromic microcapsule pigment. It is explanatory drawing which shows one Example of the writing instrument of this invention. It is explanatory drawing which shows the other Example of the writing instrument of this invention. It is explanatory drawing which shows the other Example of the writing instrument of this invention. It is explanatory drawing which shows the other Example of the writing instrument of this invention. It is explanatory drawing which shows the other Example of the writing instrument of this invention. It is explanatory drawing which shows the other Example of the writing instrument of this invention.

The colorant contained in the reversible thermochromic ink includes (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction that determines the temperature at which the color reaction occurs. It is a microcapsule pigment in which a reversible thermochromic composition that is decolored by heating containing at least three essential components of a medium is encapsulated in microcapsules.
Examples of the reversible thermochromic composition include those described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, etc., at a predetermined temperature (discoloration point). Discolored before and after, decolored state in the temperature range above the high temperature side discoloration point, color development state in the temperature range below the low temperature side discoloration point, only one specific state exists in the normal temperature range among the two states, The other state is maintained as long as the heat or cold required to develop the state is applied, but when the heat or cold is no longer applied, the hysteresis width returns to the state exhibited in the normal temperature range. It has relatively small characteristics (ΔH = 1 to 7 ° C.) (see FIG. 1).

In addition, large hysteresis characteristics (ΔH _B = 8 to 50 ° C.) described in JP- _B -4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936, and the like. ), That is, when the shape of the curve plotting the change in the color density due to the temperature change is lowering the temperature from the lower temperature side than the color changing temperature range, as opposed to increasing the temperature from the lower temperature side. In the specific temperature range, the color changes in a low temperature range below the complete color development temperature (t ₁ ) or the color erase state in the high temperature range above the complete color erase temperature (t ₄ ). A heat-erasable microcapsule pigment in which a reversible thermochromic composition having color memory in a temperature range between t _{2 and} t ₃ (substantially two-phase holding temperature range) is encapsulated in microcapsules Applicable (Fig. 2 Irradiation).

The hysteresis characteristic in the color density-temperature curve of the reversible thermochromic composition will be described.
In FIG. 2, the vertical axis represents color density and the horizontal axis represents temperature. The change in color density due to the temperature change proceeds along the arrow. Here, A is a point indicating a density at a temperature t ₄ (hereinafter referred to as a complete decoloring temperature) that reaches a completely decolored state, and B is a temperature t ₃ (hereinafter referred to as a decoloring start temperature). C is a point indicating a density at a temperature t ₂ at which color development starts (hereinafter referred to as a color development start temperature), and D is a temperature t ₁ at which a complete color development state is reached (hereinafter referred to as a complete color development state). This is a point indicating a density at a color development temperature).
Discoloration temperature region is a temperature range between the t ₁ and t _4, both states of the colored state and the decolored state can coexist, a temperature range of between t ₂ and t ₃ is a region having a large difference in color density It is a real discoloration temperature range.
The length of the line segment EF is a scale indicating the discoloration contrast, and the length of the line segment HG passing through the midpoint of the line segment EF is a temperature width indicating the degree of hysteresis (hereinafter referred to as hysteresis width ΔH). If this ΔH value is small, only one specific state can exist in the normal temperature range among both states before and after the color change. Further, when the ΔH value is large, it is easy to maintain each state before and after the color change.

Specifically, as the reversible thermochromic composition having color memory, a complete color development temperature t ₁ can be obtained only in a freezing room, a cold district, etc., that is, −50 to 0 ° C., preferably −40 to − 5 ° C., more preferably −30 to −10 ° C., and the temperature at which the complete decoloring temperature t ₄ is obtained from a frictional heat generated by a friction body, a heating body such as a hair dryer, that is, 45 to 95 ° C., preferably 50 to 90
By specifying the temperature in the range of 60 ° C., more preferably in the range of 60 to 80 ° C., and specifying the ΔH value in the range of 40 to 100 ° C., it is possible to effectively function to maintain the color exhibited in the normal state (daily life temperature range).

Specific examples of the compounds (a), (b) and (c) are shown below.
Examples of the electron donating color-forming organic compound as component (a) of the present invention include diphenylmethane phthalides, phenyl indolyl phthalides, indolyl phthalides, diphenyl methane azaphthalides, and phenyl indolyl azaphthalides. , Fluorans, stylinoquinolines, diazarhodamine lactones and the like.
Examples of these compounds are given below.
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide,
3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide,
3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide,
3,3-bis (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,
3- [2-ethoxy-4- (N-ethylanilino) phenyl] -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide,
3,6-diphenylaminofluorane,
3,6-dimethoxyfluorane,
3,6-di-n-butoxyfluorane,
2-methyl-6- (N-ethyl-Np-tolylamino) fluorane,
3-chloro-6-cyclohexylaminofluorane,
2-methyl-6-cyclohexylaminofluorane,
2- (2-chloroanilino) -6-di-n-butylaminofluorane,
2- (3-trifluoromethylanilino) -6-diethylaminofluorane,
2- (N-methylanilino) -6- (N-ethyl-Np-tolylamino) fluorane,
1,3-dimethyl-6-diethylaminofluorane,
2-chloro-3-methyl-6-diethylaminofluorane,
2-anilino-3-methyl-6-diethylaminofluorane,
2-anilino-3-methyl-6-di-n-butylaminofluorane,
2-xylidino-3-methyl-6-diethylaminofluorane,
1,2-benz-6-diethylaminofluorane,
1,2-benz-6- (N-ethyl-N-isobutylamino) fluorane,
1,2-benz-6- (N-ethyl-N-isoamylamino) fluorane,
2- (3-methoxy-4-dodecoxystyryl) quinoline,
Spiro [5H- (1) benzopyrano (2,3-d) pyrimidine-5,1 '(3'H) isobenzofuran] -3'-one,
2- (diethylamino) -8- (diethylamino) -4-methyl-spiro [5H- (1) benzopyrano (2,3-g) pyrimidine-5,1 ′ (3′H) isobenzofuran] -3-one,
2- (Di-n-butylamino) -8- (di-n-butylamino) -4-methyl-spiro [5H- (1) benzopyrano (2,3-g) pyrimidine-5,1 '(3' H) Isobenzofuran] -3-one,
2- (Di-n-butylamino) -8- (diethylamino) -4-methyl-spiro [5H- (1) benzopyrano (2,3-g) pyrimidine-5,1 '(3'H) isobenzofuran] -3-one,
2- (Di-n-butylamino) -8- (N-ethyl-Ni-amylamino) -4-methyl-spiro [5H- (1) benzopyrano (2,3-g) pyrimidine-5,1 ' (3′H) isobenzofuran] -3-one,
3- (2-methoxy-4-dimethylaminophenyl) -3- (1-butyl-2-methylindol-3-yl) -4,5,6,7-tetrachlorophthalide,
3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4,5,6,7-tetrachlorophthalide,
3- (2-ethoxy-4-diethylaminophenyl) -3- (1-pentyl-2-methylindol-3-yl) -4,5,6,7-tetrachlorophthalide,
3 ′, 6′-bis [phenyl (2-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9 ′-[9H] xanthen] -3-one,
3 ′, 6′-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9 ′-[9H] xanthen] -3-one,
And 3 ', 6'-bis [phenyl (3-ethylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-[9H] xanthen] -3-one.
Furthermore, there can be mentioned pyridine-based, quinazoline-based, bisquinazoline-based compounds and the like that are effective in developing fluorescent yellow to red color development.

As the electron-accepting compound of component (b), a group of compounds having active protons, a group of pseudo-acidic compounds [a group of compounds that are not acids but act as an acid in the composition to cause coloration of component (a)], electrons There is a group of compounds having pores.
Examples of compounds having active protons include monophenols to polyphenols as compounds having phenolic hydroxyl groups, and alkyl groups, aryl groups, acyl groups, alkoxycarbonyl groups, carboxy groups and esters thereof as substituents. Alternatively, those having an amide group, a halogen group, etc., and bis-type and tris-type phenols, phenol-aldehyde condensation resins and the like can be mentioned. Moreover, the metal salt of the compound which has the said phenolic hydroxyl group may be sufficient.

Specific examples are given below.
Phenol, o-cresol, tertiary butylcatechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, n-butyl p-hydroxybenzoate N-octyl p-hydroxybenzoate, resorcin, 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-hydroxyphenyl) sulfide, 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4 -Hydroxyphenyl) -3-methylbu 1,1-bis (4-hydroxyphenyl) -2-methylpropane, 1,1-bis (4-hydroxyphenyl) n-hexane, 1,1-bis (4-hydroxyphenyl) n-heptane, , 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) ethylpropionate, 2,2-bis (4-hydroxyphenyl)- 4-methylpentane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4-hydroxyphenyl) n-heptane, 2,2-bis It is 4-hydroxyphenyl) n- nonane.
The compound having a phenolic hydroxyl group can develop the most effective thermochromic property, but aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms, carboxylic acid metal salts, acidic phosphate esters and their It may be a compound selected from metal salts, 1,2,3-triazole and derivatives thereof.

The component (c) of the reaction medium that causes the electron transfer reaction by the components (a) and (b) to occur reversibly in a specific temperature range will be described. Examples of the component (c) include esters, ketones, ethers, alcohols, and acid amides.
As the component (c), the color density-temperature curve has a large hysteresis characteristic (a curve plotting a change in color density due to a temperature change changes the temperature from the low temperature side to the high temperature side, and the high temperature side to the low temperature side). A carboxylic acid ester compound exhibiting a ΔT value (melting point-cloud point) of 5 ° C. or more and less than 50 ° C., which can form a reversible thermochromic composition exhibiting color memory, which changes color when changing to Carboxylic acid ester having a substituted aromatic ring in the molecule, carboxylic acid ester having an unsubstituted aromatic ring and an aliphatic alcohol ester having 10 or more carbon atoms, carboxylic acid ester having a cyclohexyl group in the molecule, 6 or more carbon atoms Fatty acid and unsubstituted aromatic alcohol or phenol ester, fatty acid having 8 or more carbon atoms and branched aliphatic alcohol or ester, dicarboxylic acid and aroma Ester of alcohol or branched aliphatic alcohol, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, dicetyl adipate, distearyl adipate, trilaurin, trimyristin, tristearin, dimyristin, Distearin or the like is used.

Also, fatty acid ester compounds obtained from an odd aliphatic monohydric alcohol having 9 or more carbon atoms and an aliphatic carboxylic acid having an even number of carbon atoms, n-pentyl alcohol or n-heptyl alcohol and an even fat having 10 to 16 carbon atoms. A fatty acid ester compound having a total carbon number of 17 to 23 obtained from a group carboxylic acid is also effective.
Specifically, n-pentadecyl acetate, n-tridecyl butyrate, n-pentadecyl butyrate, n-undecyl caproate, n-tridecyl caproate, n-pentadecyl caproate, n-nonyl caprylate, n-undecyl caprylate, N-tridecyl caprylate, n-pentadecyl caprylate, n-heptyl caprate, n-nonyl caprate, n-undecyl caprate, n-tridecyl caprate, n-pentadecyl caprate, n-pentyl laurate, lauric acid n-heptyl, n-nonyl laurate, n-undecyl laurate, n-tridecyl laurate, n-pentadecyl laurate, n-pentyl myristate, n-heptyl myristate, n-nonyl myristate, n-myristate Undecyl, n-tridecyl myristate, N-pentadecyl ristinate, n-pentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-undecyl palmitate, n-tridecyl palmitate, n-pentadecyl palmitate, n-nonyl stearate, stearic acid n-undecyl, n-tridecyl stearate, n-pentadecyl stearate, n-nonyl eicosanoate, n-undecyl eicosanoate, n-tridecyl eicosanoate, n-pentadecyl eicosanoate, n-nonyl behenate, n-behenate Examples include undecyl, n-tridecyl behenate, and n-pentadecyl behenate.

As the ketones, aliphatic ketones having a total carbon number of 10 or more are effective, and 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, 5-undecanone, 2 -Dodecanone, 3-dodecanone, 4-dodecanone, 5-dodecanone, 2-tridecanone, 3-tridecanone, 2-tetradecanone, 2-pentadecanone, 8-pentadecanone, 2-hexadecanone, 3-hexadecanone, 9-heptadecanone, 2-pentadecanone 2-octadecanone, 2-nonadecanone, 10-nonadacanone, 2-eicosanone, 11-eicosanone, 2-heneicosanone, 2-docosanone, laurone, stearone and the like.
Further, arylalkyl ketones having 12 to 24 carbon atoms in total, such as n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecano Phenone, 4-n-dodecanacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonylacetophenone, n -Decanophenone, 4-n-octylacetophenone, n-nonanophenone, 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butylpropiophenone, n-heptaphenone, 4-n-pentylacetophene Emissions, cyclohexyl phenyl ketone, benzyl -n- butyl ketone, 4-n-butyl acetophenone, n- hexanophenone, 4-isobutyl acetophenone, 1-acetonaphthone, 2-acetonaphthone, may be mentioned cyclopentyl phenyl ketone.

As ethers, aliphatic ethers having a total carbon number of 10 or more are effective, and include dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditrityl ether. Decyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether, dioctadecyl ether, decane diol dimethyl ether, undecane diol dimethyl ether, dodecane diol dimethyl ether, tridecane diol dimethyl ether, decane diol diethyl ether, undecane diol diethyl ether, etc. Can be mentioned.
As the alcohols, aliphatic monovalent saturated alcohols having 10 or more carbon atoms are effective. Decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl Alcohol, octadecyl alcohol, eicosyl alcohol, docosyl alcohol, etc. can be mentioned.
Acid amides include hexanoic acid amide, heptanoic acid amide, octanoic acid amide, nonanoic acid amide, decanoic acid amide, undecanoic acid amide, lauric acid amide, tridecanoic acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, Examples thereof include docosanoic acid amide.

〔式中、Ｒ_１は水素原子又はメチル基を示し、ｍは０〜２の整数を示し、Ｘ_１、Ｘ_２のいずれか一方は−（ＣＨ_２）_ｎＯＣＯＲ_２又は−（ＣＨ_２）_ｎＣＯＯＲ_２、他方は水素原子を示し、ｎは０〜２の整数を示し、Ｒ_２は炭素数４以上のアルキル基又はアルケニル基を示し、Ｙ_１及びＹ_２は水素原子、炭素数１〜４のアルキル基、メトキシ基、又は、ハロゲンを示し、ｒ及びｐは１〜３の整数を示す。〕
前記式（１）で示される化合物のうち、Ｒ_１が水素原子の場合、より広いヒステリシス幅を有する可逆熱変色性組成物が得られるため好適であり、更にＲ_１が水素原子であり、且つ、ｍが０の場合がより好適である。
なお、式（１）で示される化合物のうち、より好ましくは下記一般式（２）で示される化合物が用いられる。

式中のＲは炭素数８以上のアルキル基又はアルケニル基を示すが、好ましくは炭素数１０〜２４のアルキル基、更に好ましくは炭素数１２〜２２のアルキル基である。
前記化合物として具体的には、オクタン酸−４−ベンジルオキシフェニルエチル、ノナン酸−４−ベンジルオキシフェニルエチル、デカン酸−４−ベンジルオキシフェニルエチル、ウンデカン酸−４−ベンジルオキシフェニルエチル、ドデカン酸−４−ベンジルオキシフェニルエチル、トリデカン酸−４−ベンジルオキシフェニルエチル、テトラデカン酸−４−ベンジルオキシフェニルエチル、ペンタデカン酸−４−ベンジルオキシフェニルエチル、ヘキサデカン酸−４−ベンジルオキシフェニルエチル、ヘプタデカン酸−４−ベンジルオキシフェニルエチル、オクタデカン酸−４−ベンジルオキシフェニルエチルを例示できる。 In addition, a compound represented by the following general formula (1) is preferably used as the component (c).

[Wherein, R ₁ represents a hydrogen atom or a methyl group, m represents an integer of 0 to 2, and _one of X ₁ and X ₂ represents — (CH ₂ ) _n OCOR ₂ or — (CH ₂ ) _n COOR ₂ , the other represents a hydrogen atom, n represents an integer of 0 to 2, R ₂ represents an alkyl or alkenyl group having 4 or more carbon atoms, Y ₁ and Y ₂ represent a hydrogen atom, 1 to 4 carbon atoms An alkyl group, a methoxy group, or halogen, and r and p each represent an integer of 1 to 3. ]
Among the compounds represented by the formula (1), when R ₁ is a hydrogen atom, it is preferable because a reversible thermochromic composition having a wider hysteresis width can be obtained, and R ₁ is a hydrogen atom, and , M is more preferably 0.
Of the compounds represented by the formula (1), a compound represented by the following general formula (2) is more preferably used.

R in the formula represents an alkyl group or alkenyl group having 8 or more carbon atoms, preferably an alkyl group having 10 to 24 carbon atoms, more preferably an alkyl group having 12 to 22 carbon atoms.
Specific examples of the compound include octanoic acid-4-benzyloxyphenylethyl, nonanoic acid-4-benzyloxyphenylethyl, decanoic acid-4-benzyloxyphenylethyl, undecanoic acid-4-benzyloxyphenylethyl, and dodecanoic acid. -4-benzyloxyphenylethyl, tridecanoic acid-4-benzyloxyphenylethyl, tetradecanoic acid-4-benzyloxyphenylethyl, pentadecanoic acid-4-benzyloxyphenylethyl, hexadecanoic acid-4-benzyloxyphenylethyl, heptadecanoic acid Examples thereof include -4-benzyloxyphenylethyl and octadecanoic acid-4-benzyloxyphenylethyl.

（式中、Ｒは炭素数８以上のアルキル基又はアルケニル基を示し、ｍ及びｎはそれぞれ１〜３の整数を示し、Ｘ及びＹはそれぞれ水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、ハロゲンを示す。）
前記化合物として具体的には、オクタン酸１,１−ジフェニルメチル、ノナン酸１,１−ジフェニルメチル、デカン酸１,１−ジフェニルメチル、ウンデカン酸１,１−ジフェニルメチル、ドデカン酸１,１−ジフェニルメチル、トリデカン酸１,１−ジフェニルメチル、テトラデカン酸１,１−ジフェニルメチル、ペンタデカン酸１,１−ジフェニルメチル、ヘキサデカン酸１,１−ジフェニルメチル、ヘプタデカン酸１,１−ジフェニルメチル、オクタデカン酸１,１−ジフェニルメチルを例示できる。 Furthermore, a compound represented by the following general formula (3) can also be used as the component (c).

(In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, m and n each represents an integer of 1 to 3, X and Y represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, carbon, respectively. (The alkoxy group of Formula 1-4 is shown, and a halogen.)
Specific examples of the compound include 1,1-diphenylmethyl octanoate, 1,1-diphenylmethyl nonanoate, 1,1-diphenylmethyl decanoate, 1,1-diphenylmethyl undecanoate, 1,1-dodecanoic acid 1,1- Diphenylmethyl, tridecanoic acid 1,1-diphenylmethyl, tetradecanoic acid 1,1-diphenylmethyl, pentadecanoic acid 1,1-diphenylmethyl, hexadecanoic acid 1,1-diphenylmethyl, heptadecanoic acid 1,1-diphenylmethyl, octadecanoic acid An example is 1,1-diphenylmethyl.

（式中、Ｘは水素原子、炭素数１乃至４のアルキル基、メトキシ基、ハロゲン原子のいずれかを示し、ｍは１乃至３の整数を示し、ｎは１乃至２０の整数を示す。）
前記化合物としては、マロン酸と２−〔４−(４−クロロベンジルオキシ）フェニル）〕エタノールとのジエステル、こはく酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、こはく酸と２−〔４−(３−メチルベンジルオキシ）フェニル）〕エタノールとのジエステル、グルタル酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、グルタル酸と２−〔４−(４−クロロベンジルオキシ）フェニル）〕エタノールとのジエステル、アジピン酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、ピメリン酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、スベリン酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、スベリン酸と２−〔４−(３−メチルベンジルオキシ）フェニル）〕エタノールとのジエステル、スベリン酸と２−〔４−(４−クロロベンジルオキシ）フェニル）〕エタノールとのジエステル、スベリン酸と２−〔４−(２，４−ジクロロベンジルオキシ）フェニル）〕エタノールとのジエステル、アゼライン酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、セバシン酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、１，１０−デカンジカルボン酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、１，１８-オクタデカンジカルボン酸と２−（４−ベンジルオキシフェニル）エタノールとのジエステル、１，１８-オクタデカンジカルボン酸と２−〔４−(２−メチルベンジルオキシ）フェニル）〕エタノールとのジエステルを例示できる。 Furthermore, a compound represented by the following general formula (4) can also be used as the component (c).

(Wherein, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20)
Examples of the compound include a diester of malonic acid and 2- [4- (4-chlorobenzyloxy) phenyl)] ethanol, a diester of succinic acid and 2- (4-benzyloxyphenyl) ethanol, succinic acid and 2- Diester with [4- (3-methylbenzyloxy) phenyl)] ethanol, diester with glutaric acid and 2- (4-benzyloxyphenyl) ethanol, glutaric acid and 2- [4- (4-chlorobenzyloxy) Phenyl)] ethanol diester, adipic acid and 2- (4-benzyloxyphenyl) ethanol diester, pimelic acid and 2- (4-benzyloxyphenyl) ethanol diester, suberic acid and 2- (4- Diester with benzyloxyphenyl) ethanol, suberic acid and 2- [4- (3-methyl Benzyloxy) phenyl)] ethanol diester, suberic acid and 2- [4- (4-chlorobenzyloxy) phenyl)] ethanol diester, suberic acid and 2- [4- (2,4-dichlorobenzyloxy) ) Phenyl)] ethanol diester, azelaic acid and 2- (4-benzyloxyphenyl) ethanol diester, sebacic acid and 2- (4-benzyloxyphenyl) ethanol diester, 1,10-decanedicarboxylic acid And 2- (4-benzyloxyphenyl) ethanol diester, 1,18-octadecanedicarboxylic acid and 2- (4-benzyloxyphenyl) ethanol diester, 1,18-octadecanedicarboxylic acid and 2- [4- (2-Methylbenzyloxy) phenyl)] die with ethanol It can be exemplified ether.

（式中、Ｒは炭素数１乃至２１のアルキル基又はアルケニル基を示し、ｎは１乃至３の整数を示す。）
前記化合物としては、１，３−ビス（２−ヒドロキシエトキシ）ベンゼンとカプリン酸とのジエステル、１，３−ビス（２−ヒドロキシエトキシ）ベンゼンとウンデカン酸とのジエステル、１，３−ビス（２−ヒドロキシエトキシ）ベンゼンとラウリン酸とのジエステル、１，３−ビス（２−ヒドロキシエトキシ）ベンゼンとミリスチン酸とのジエステル、１，４−ビス（ヒドロキシメトキシ）ベンゼンと酪酸とのジエステル、１，４−ビス（ヒドロキシメトキシ）ベンゼンとイソ吉草酸とのジエステル、１，４−ビス（２−ヒドロキシエトキシ）ベンゼンと酢酸とのジエステル、１，４−ビス（２−ヒドロキシエトキシ）ベンゼンとプロピオン酸とのジエステル、１，４−ビス（２−ヒドロキシエトキシ）ベンゼンと吉草酸とのジエステル、１，４−ビス（２−ヒドロキシエトキシ）ベンゼンとカプロン酸とのジエステル、１，４−ビス（２−ヒドロキシエトキシ）ベンゼンとカプリル酸とのジエステル、１，４−ビス（２−ヒドロキシエトキシ）ベンゼンとカプリン酸とのジエステル、１，４−ビス（２−ヒドロキシエトキシ）ベンゼンとラウリン酸とのジエステル、１，４−ビス（２−ヒドロキシエトキシ）ベンゼンとミリスチン酸とのジエステルを例示できる。 Furthermore, a compound represented by the following general formula (5) can also be used as the component (c).

(In the formula, R represents an alkyl group or alkenyl group having 1 to 21 carbon atoms, and n represents an integer of 1 to 3).
Examples of the compound include a diester of 1,3-bis (2-hydroxyethoxy) benzene and capric acid, a diester of 1,3-bis (2-hydroxyethoxy) benzene and undecanoic acid, and 1,3-bis (2 -Hydroxyethoxy) benzene and lauric acid diester, 1,3-bis (2-hydroxyethoxy) benzene and myristic acid diester, 1,4-bis (hydroxymethoxy) benzene and butyric acid diester, 1,4 Diesters of bis (hydroxymethoxy) benzene and isovaleric acid, diesters of 1,4-bis (2-hydroxyethoxy) benzene and acetic acid, and 1,4-bis (2-hydroxyethoxy) benzene and propionic acid Diester, diester of 1,4-bis (2-hydroxyethoxy) benzene and valeric acid Diester of 1,4-bis (2-hydroxyethoxy) benzene and caproic acid, diester of 1,4-bis (2-hydroxyethoxy) benzene and caprylic acid, 1,4-bis (2-hydroxyethoxy) benzene And diester of capric acid, 1,4-bis (2-hydroxyethoxy) benzene and lauric acid, and 1,4-bis (2-hydroxyethoxy) benzene and myristic acid.

  Furthermore, as an electron-accepting compound, a specific alkoxyphenol compound having a linear or side chain alkyl group having 3 to 18 carbon atoms (Japanese Patent Laid-Open No. 11-129623), a specific hydroxybenzoic acid ester (Japanese Patent Laid-Open No. 2001-105732). Gazette), gallic acid ester (Japanese Patent Laid-Open No. 2003-253149) and the like, and a heat-colorable microcapsule pigment encapsulating a reversible thermochromic composition can also be applied (see FIG. 3).

The blending ratio of the components (a), (b), and (c) depends on the concentration, the color change temperature, the color change form, and the type of each component. In general, the component ratio at which a desired color change characteristic is obtained is as follows. (B) Component 1 is in the range of (b) Component 0.1-50, preferably 0.5-20, (c) Component 1-800, preferably 5-200. Part by mass).
Here, in the reversible thermochromic microcapsule pigment or the ink, a colorant such as a non-thermochromic dye or pigment is blended to change the color from color (1) to color (2). Changes can also be exhibited.

  The microencapsulation of the reversible thermochromic composition includes interfacial polymerization method, interfacial polycondensation method, in situ polymerization method, submerged curing coating method, phase separation method from aqueous solution, phase separation method from organic solvent, melt dispersion There are a cooling method, an air suspension coating method, a spray drying method, and the like, which are appropriately selected according to the application. 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 may have a circular cross section or a non-circular cross section.
Here, it is preferable that the reversible thermochromic composition: wall film = 7: 1 to 1: 1 (mass ratio), preferably 6: 1 to 1: 1.
When the ratio of the reversible thermochromic composition to the wall film is larger than the above range, the thickness of the wall film becomes too thin, and the resistance to pressure and heat tends to decrease, and the ratio of the wall film to the reversible thermochromic composition When the value is larger than the above range, color density and sharpness during color development tend to be reduced.
The microcapsule pigments having an average particle size of 0.01 to 5.0 μm, preferably 0.1 to 4.0 μm, more preferably 0.5 to 3.0 μm satisfy practicality.
When the average particle diameter exceeds 5.0 μm, ink outflow properties are easily impaired. On the other hand, in a system of less than 0.01 μm, it is difficult to show a high density color developability.
The particle diameter is measured using a laser diffraction / scattering particle size distribution measuring apparatus (manufactured by Horiba, Ltd .; LA-300), and the average particle diameter (median diameter) is calculated based on the numerical value. .

The reversible thermochromic microcapsule pigment can be blended in an amount of 5 to 40% by mass, preferably 10 to 40% by mass, and more preferably 15 to 35% by mass with respect to the total amount of the ink composition.
If it is less than 5% by mass, the color density is insufficient, and if it exceeds 40% by mass, the ink outflow is reduced and writing performance is impaired.

As a medium used for the ink, water and, if necessary, a water-soluble organic solvent are used.
Examples of the water-soluble organic solvent include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, and ethylene glycol monomethyl. Ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N-methyl-2- Pyrrolidone, or the like is used.
Note that the microcapsule pigment encapsulating the reversible thermochromic composition having a large hysteresis width has a specific gravity of more than 1, so that the water-soluble organic solvent to be applied is preferably more than 1.1.

By adding a water-soluble polymer flocculant into the ink, the flocculant causes a loose bridging action between the microcapsule pigment particles, and exhibits a loose aggregation state. Such an ink exhibiting a loose aggregation state can suppress the separation of the microcapsule pigment.
A water-soluble polymer is used as the polymer flocculant, and examples thereof include polyvinyl pyrrolidone, polyethylene oxide, and water-soluble polysaccharides.
Examples of the water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, water-soluble cellulose derivatives and the like. Specific examples of water-soluble cellulose derivatives include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose. Etc.
In the reversible thermochromic water-based ink composition of the present invention, any water-soluble polymer exhibiting a loose bridging action between microcapsule pigment particles can be applied, and water-soluble cellulose derivatives are particularly effective. Function.
Two or more kinds of the polymer flocculants can be used in combination.

Combining the polymer flocculant with a comb polymer dispersant having a carboxyl group in the side chain and an organic nitrogen sulfur compound improves dispersibility of loose aggregates of microcapsule pigments by the polymer flocculant. .
The comb polymer dispersant having a carboxyl group in the side chain is not particularly limited as long as it is a comb polymer compound having a plurality of carboxyl groups in the side chain, but a plurality of carboxyl groups in the side chain. An acrylic polymer compound having the formula:

The organic nitrogen sulfur compound further suppresses settling of the microcapsule pigment due to vibration when the ink composition is filled in a writing instrument and put to practical use.
This further improves dispersibility in which loose aggregates of microcapsule pigments are dispersed by a comb-type polymer dispersant having a carboxyl group in the side chain.
As the organic nitrogen sulfur compound, a compound selected from thiazole compounds, isothiazole compounds, benzothiazole compounds, and benzoisothiazole compounds is used.
Specific examples of the organic nitrogen sulfur compound include 2- (4-thiazoyl) -benzimidazole (TBZ), 2- (thiocyanatomethylthio) -1,3-benzothiazole (TCMTB), 2-methyl-4-isothiazoline- One or more compounds selected from 3-one and 5-chloro-2-methyl-4-isothiazolin-3-one are used, preferably 2- (4-thiazoyl) -benzimidazole (TBZ), 2 One or more compounds selected from -methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one are used.
As the organic nitrogen sulfur compound, manufactured by Permachem Asia Co., Ltd., trade names: Topside 88, 133, 170, 220, 288, 300, 400, 500, 600, 700Z, 800, 950, manufactured by Hokuko Sangyo Co., Ltd., trade names: Hokuster HP, E50A, Hokuside P200, 6500, 7400, MC, 369, and R-150.
The mass ratio of the comb-type polymer dispersant having a carboxyl group in the side chain and the organic nitrogen sulfur compound is 1: 1 to 1:10, preferably 1: 1 to 1: 5, and satisfies the above range. Thus, the dispersibility of loose aggregates of the microcapsule pigment and the suppression of sedimentation of the microcapsule pigment due to vibration can be sufficiently expressed.

As the dispersion stabilizer, a water-soluble resin is used, and it has a function of enhancing the stability of the comb-type polymer dispersant having a carboxyl group in the side chain and the organic nitrogen sulfur compound in the ink, and is fixed to the paper surface. It is also possible to impart properties and viscosity.
Examples of the water-soluble resin include alkyd resin, acrylic resin, styrene maleic acid copolymer, cellulose derivative, polyvinyl pyrrolidone, polyvinyl alcohol, dextrin, and the like. 89% partially saponified polyvinyl alcohol is preferably used.
The amount of the water-soluble resin added can be 0.3 to 3.0% by weight, preferably 0.5 to 1.5% by weight in the ink.

Examples of the polyurethane emulsion having a pH of 5 to 9 include those manufactured by Avicia, trade names: NeoRez R-972, R-9637, R2105, R-966, R-967, R-985, R-986, R-989, R-9603, R-940, R9403, manufactured by DIC Corporation, trade names: Hydran AP-20, AP-40, APX-101H, CP-7020, Sanyo Chemical Co., Ltd., trade names: Uprene UXA-307, etc. It can be illustrated.
Examples of the acrylic resin emulsion having a pH of 5 to 8 include BASF Corporation, trade name: Jocril 1535, DIC Corporation, trade name: Boncoat R-3880-E, and the like.
The polyurethane emulsion or acrylic resin emulsion having a pH of 5 to 9 is excellent in dispersion stability in an ink composition having a pH of 5 to 8, and thus exhibits excellent handwriting fixing power. In particular, coated paper, resin film, etc. The ink is difficult to permeate and has high fixability, and the handwriting is hardly peeled off by rubbing.
The polyurethane emulsion or the acrylic resin emulsion can be added in an amount of 1 to 15% by weight, preferably 2 to 10% by weight in the ink composition as a solid content.
If it is less than 1% by weight, it is difficult to obtain the desired fixing property, and even if it exceeds 15% by weight, no further improvement in fixing property can be obtained, so no further addition is required.
The pH of the emulsion is preferably 5 or more and less than 9.

The ink composition can suppress aggregation and sedimentation in a low temperature region of the reversibly thermochromic microcapsule pigment contained by adjusting the pH to 5 to 8, preferably 6 to 8.
If the pH exceeds 8, it tends to impair ink outflow properties when left in a low temperature range, that is, a temperature range where the ink freezes. The color developability becomes strong, and there may be a problem that a color residue is generated at the time of decoloring.
The dispersion stabilizer is preferably a water-soluble resin that is soluble when the pH of the ink composition is in the range of 5-8.
The pH of the ink composition and the resin emulsion is measured using a pH meter (manufactured by Toa DKK, product number: HM-20P, glass electrode type hydrogen ion concentration indicator).

The ink composition has a surface tension adjusted to 25 to 45 mN / m, preferably 30 to 45 mN / m, more preferably 30 to 40 mN / m.
By adjusting the surface tension within the above range, it is difficult to cause blurring when written, and the ink can be left in a temperature range below 0 ° C. where the ink freezes or even in a high temperature range, for example, 50 ° C. It is difficult to cause variations in handwriting density and writing width depending on the storage environment and use environment without impairing the flowability.
When the surface tension is less than 25 mN / m, the outflow property of the ink tends to be unstable, and the handwriting density becomes non-uniform. Further, when the surface tension exceeds 45 mN / m, line breakage is likely to occur, and the ink outflow amount decreases due to the storage environment and use environment described above, and the handwriting density decreases, and the writing width tends to vary. .

  In addition, benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin and other anticorrosives, urea, nonionic surfactants, reduced or non-reduced starch hydrolysates, trehalose, etc. Wetting agents such as saccharides, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbit, mannitol, sodium pyrophosphate, antifoaming agents, fluorine surfactants and nonionic surfactants that improve ink permeability May be used.

The pen body is preferably a marking pen body, and examples thereof include a pen body made of fiber, felt, plastic, or the like.
The tip shape of the marking pen body may be either a bullet type or a chisel type.
In addition, a brush pen body and a ballpoint pen body can be used. As the brush pen body, a fiber bundling body in which fibers are closely bundled in the longitudinal direction, a plastic porous body having continuous pores, and a heat-sealing of synthetic resin fibers. Examples thereof include a resin processed body, and a soft resin or elastomer extrusion processed body.
As the ballpoint pen body, metal is cut to form a ball receiving seat and an ink lead-out portion inside, a plurality of inward protruding portions are provided on the inner surface near the tip of the metal pipe by pressing deformation from the outer surface, An ink outflow gap extending radially outward from the central portion between the inward protruding portions is exemplified.
The ball held by the ballpoint pen body is 0.3 to 2.0 mm in diameter, preferably 0.4 to 1.5 mm, more preferably 0.5 to 1, such as cemented carbide, stainless steel, ruby, and ceramic. A ball of 0.0 mm is effective.
The ballpoint pen body is provided with a resilient member that bounces the rear end of the ball forward. When not writing, the ball is pressed against the inner edge of the tip of the pen body to bring it into close contact. The ink can be made to flow backward by allowing it to retreat.
As the shaft cylinder, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon is preferably used.
In addition, as a structure of the writing instrument for containing the ink composition, a direct liquid writing instrument having a structure in which a valve mechanism is arranged in the shaft cylinder and the ink in the shaft cylinder is led to the pen body by opening the valve, Direct ink writing instruments with a structure in which ink is directly stored in the ink flow adjusting member composed of a comb groove-like ink flow adjusting member and a fiber bundle are included. A solid writing instrument having a structure in which the body is impregnated, the pen body is attached to the writing tip, and the rear end of the pen body is in contact with the ink occlusion body directly or via a connecting member is preferable.
The ink occlusion body is formed by converging crimped fibers in the longitudinal direction, and is configured to be included in a covering body such as a plastic cylinder or a film and to adjust the porosity to a range of approximately 40 to 90%. Is done. The fiber bundle may be one that has been processed by resin processing, heat sealing, or plasticizer.

The ballpoint pen refill can be accommodated in a shaft tube to obtain a cap-type ballpoint pen.
Further, the ballpoint pen refill can be accommodated in a shaft cylinder to obtain a retractable ballpoint pen. The ballpoint pen refill is stored in the shaft cylinder with the tip exposed to the outside air, and the operation of the retracting mechanism is performed. Thus, the writing tip protrudes from the shaft tube opening.
Examples of the appearance mechanism include a knock type, a rotary type, and a slide type.
The knock type has a knock portion on the rear end portion of the shaft tube and the side surface of the shaft tube, and by pressing the knock portion, the writing tip portion of the ballpoint pen refill is projected and retracted from the front end opening portion of the shaft tube, or on the shaft tube. The structure which makes the writing tip part of a ball-point pen refill appear and disappear from the axial cylinder front-end opening part by pressing the provided clip part can be illustrated.
The rotary type has a rotating part at the rear part of the shaft cylinder, and can be exemplified by a configuration in which the writing tip part of the ballpoint pen refill is projected and retracted from the front end part of the shaft cylinder by turning the rotating part.
The slide type has a slide part on the side surface of the shaft cylinder, and the sliding tip of the writing point of the ballpoint pen refill is projected and retracted from the front end opening of the shaft cylinder by operating the slide, or the clip part provided on the shaft cylinder is slid. By doing so, it is possible to exemplify a configuration in which the writing tip portion of the ballpoint pen refill is projected and retracted from the opening at the front end of the shaft cylinder.
The retractable ballpoint pen is a compound type retractable ballpoint pen in which a plurality of ballpoint pen refills are accommodated in a shaft cylinder, and the writing tip of one of the ballpoint pen refills protrudes and retracts from the opening at the front end of the shaft cylinder by the operation of the retractable mechanism. May be.

The handwriting formed from the writing instrument containing the ink composition can be discolored by friction with a finger or application of a heating tool or a cooling tool.
Examples of the heating tool include an energization heating color changing tool equipped with a resistance heating element, a heating color changing tool filled with hot water, and a hair dryer. Preferably, a friction member or a friction body that can change color by a simple method is used. Is used.
The friction member or the friction body is preferably an elastic body such as an elastomer or a plastic foam which is rich in elasticity and can generate frictional heat by generating appropriate friction during friction. Wood, metal, and fabric may be used.
Although it is possible to rub the handwriting by using an eraser, it is preferable to use a friction member as described above because erase scraps are easily generated during friction.
As the material of the friction member and friction body, silicone resin, SEBS resin (styrene ethylene butadiene styrene block copolymer), and polyester resin are preferably used. Since the handwriting tends to be repelled when writing repeatedly, SEBS resin and polyester resin are more preferably used.
The friction member may be an arbitrary-shaped member (friction body) that is separate from the writing instrument, but is excellent in portability by fixing the friction member to the writing instrument.
In the case of a writing instrument having a cap, the location where the friction member is provided is not particularly limited. For example, when the cap itself is formed of a friction member, the shaft tube itself is formed of a friction member, or a clip is provided. The clip itself can be formed of a friction member, or the friction member can be provided at the tip end (top) of the cap or the rear end of the shaft cylinder (the portion where the writing tip is not provided).
In the case of a retractable writing instrument, the location where the friction member is provided is not particularly limited, but for example, the shaft cylinder itself is formed with a friction member, or when the clip is provided, the clip itself is formed with a friction member, A friction member can be provided in the vicinity of the shaft tube opening, the rear end portion of the shaft tube (the portion where the writing tip portion is not provided) or the knock portion.
Examples of the cooling / heating tool include a cooling / heating discoloration tool using a Peltier element, a cooling / heating discoloration tool filled with a coolant such as cold water and ice pieces, a refrigerator and a freezer.
Moreover, a writing instrument set can be obtained by combining the writing instrument and a friction body.

Examples of the water-based ink composition for reversible thermochromic writing instruments and the writing instrument using the same according to the present invention are shown below, but the present invention is not limited thereto.
In addition, the part in an Example shows a mass part.
The surface tension of the ink was measured with an automatic surface tension meter (CBVP-A3) manufactured by Kyowa Interface Science Co., Ltd.

Example 1
Preparation of reversible thermochromic microcapsule pigment (I) 2- (dibutylamino) -8- (dipentylamino) -4-methyl-spiro [5H- [1] benzopyrano [2,3-g] pyrimidine-5 as component (a) , 1 ′ (3′H) -isobenzofuran] -3-one 1.0 part, (b) component 4,4 ′-(2-ethylhexane-1,1-diyl) diphenol 3.0 part, A reversible thermochromic composition having color memory consisting of 5.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) A microcapsule pigment suspension containing the product was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 2.3 μm, a complete color erasing temperature of 58 ° C., a complete color development temperature of −20 ° C., and changes from pink to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the above microcapsule pigment (previously cooled to -20 ° C. or less to develop a pink color), 0.5 part of hydroxyethyl cellulose, comb polymer dispersant [Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000] 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3 -One and a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, acrylic resin emulsion [manufactured by Johnson Polymer Co., Ltd., trade name: JONCRYL 74J, pH 8.4] 5.0 Parts, polyvinyl alcohol 0.5 parts, glycerin 25.0 parts, antifoaming agent 0.02 parts, water 42.48 parts are mixed to obtain a reversible thermochromic aqueous ink composition. It was.
The pH of the ink composition was 7.10.

Writing instrument production (see Fig. 4)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 3 ( A bullet type, φ4.0) was attached, and a cap 6 was fitted to obtain a direct liquid writing instrument 1 (marking pen).
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

The marking pen was used to write on the coated paper to form pink letters (handwriting).
The handwriting has a pink color at room temperature (25 ° C.). When the handwriting is rubbed with a friction body attached to the shaft tube, the handwriting is discolored and becomes colorless, and this state is maintained at room temperature. Then, by cooling to −20 ° C. or lower, the original pink color was restored, and the discoloration behavior was reproduced repeatedly.

Example 2
Preparation of reversible thermochromic microcapsule pigment (I) 2- (dibutylamino) -8- (dipentylamino) -4-methyl-spiro [5H- [1] benzopyrano [2,3-g] pyrimidine-5 as component (a) , 1 ′ (3′H) -isobenzofuran] -3-one 1.0 part, (b) component 4,4 ′-(2-ethylhexane-1,1-diyl) diphenol 3.0 part, A reversible thermochromic composition having color memory consisting of 5.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) A microcapsule pigment suspension containing the product was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle diameter of 2.0 μm, a complete color erasing temperature of 58 ° C., and a complete color development temperature of −23 ° C., which changes from pink to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the microcapsule pigment (previously cooled to -23 ° C. or less to develop a pink color), 0.5 part of hydroxyethyl cellulose, comb polymer dispersant [Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000] 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3 -One and a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, acrylic resin emulsion [manufactured by Johnson Polymer Co., Ltd., trade name: JONCRYL 74J, pH 8.4] 5.0 Parts, polyvinyl alcohol 0.5 parts, glycerin 25.0 parts, antifoaming agent 0.02 parts, water 42.48 parts are mixed to obtain a reversible thermochromic aqueous ink composition. It was.
The pH of the ink composition was 7.10.

Writing instrument production (see Fig. 4)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 3 ( A bullet type, φ3.0) was attached, and a cap 6 was fitted to obtain a direct liquid writing instrument 1 (marking pen).
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

The marking pen was used to write on the coated paper to form pink letters (handwriting).
The handwriting has a pink color at room temperature (25 ° C.), and when it is rubbed with a friction body attached to the shaft tube, the handwriting is discolored and becomes colorless, and this state is maintained at room temperature. Then, by cooling to −23 ° C. or lower, the original pink color was restored, and the discoloration behavior was reproduced repeatedly.

Example 3
Preparation of reversible thermochromic microcapsule pigment (I) 2- (dibutylamino) -8- (dipentylamino) -4-methyl-spiro [5H- [1] benzopyrano [2,3-g] pyrimidine-5 as component (a) , 1 ′ (3′H) -isobenzofuran] -3-one 1.0 part, (b) component 4,4 ′-(2-ethylhexane-1,1-diyl) diphenol 3.0 part, A reversible thermochromic composition having color memory consisting of 5.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) A microcapsule pigment suspension containing the product was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 1.5 μm, a complete color erasing temperature of 58 ° C., and a complete color development temperature of −25 ° C., which changes from pink to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the above microcapsule pigment (previously cooled to -25 ° C. or less to develop a pink color), 0.5 part of hydroxyethyl cellulose, comb polymer dispersant [Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000] 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3 -One and a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, acrylic resin emulsion [manufactured by Johnson Polymer Co., Ltd., trade name: JONCRYL74J, pH 8.4] 5.0 parts , 0.5 parts of polyvinyl alcohol, 25.0 parts of glycerin, 0.02 part of antifoaming agent, and 42.48 parts of water are mixed to obtain a reversible thermochromic aqueous ink composition. It was.
The pH of the ink composition was 7.10.

Writing instrument production (see Fig. 4)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 3 ( A shell type, φ2.5) was attached, and a cap 6 was fitted to obtain a direct liquid writing instrument 1 (marking pen).
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

The marking pen was used to write on the coated paper to form pink letters (handwriting).
The handwriting has a pink color at room temperature (25 ° C.). When the handwriting is rubbed with a friction body attached to the shaft tube, the handwriting is discolored and becomes colorless, and this state is maintained at room temperature. Then, by cooling to −25 ° C. or lower, the original pink color was restored, and the discoloration behavior was reproduced repeatedly.

Example 4
Preparation of reversible thermochromic microcapsule pigment (I) 2- (dibutylamino) -8- (dipentylamino) -4-methyl-spiro [5H- [1] benzopyrano [2,3-g] pyrimidine-5 as component (a) , 1 ′ (3′H) -isobenzofuran] -3-one 1.0 part, (b) component 4,4 ′-(2-ethylhexane-1,1-diyl) diphenol 3.0 part, A reversible thermochromic composition having color memory consisting of 5.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) A microcapsule pigment suspension containing the product was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 1.0 μm, a complete color erasing temperature of 58 ° C., a complete color development temperature of −30 ° C., and changes from pink to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the microcapsule pigment (previously cooled to -30 ° C. or less to develop a pink color), 0.5 part of hydroxyethyl cellulose, comb polymer dispersant [Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000] 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3 -One and a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, acrylic resin emulsion [manufactured by Johnson Polymer Co., Ltd., trade name: JONCRYL 74J, pH 8.4] 5.0 Parts, polyvinyl alcohol 0.5 parts, glycerin 25.0 parts, antifoaming agent 0.02 parts, water 42.48 parts are mixed to obtain a reversible thermochromic aqueous ink composition. It was.
The pH of the ink composition was 7.10.

Writing instrument production (see Fig. 4)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 3 ( A cannonball type, φ2.0) was attached, and a cap 6 was fitted to obtain a direct liquid writing instrument 1 (marking pen).
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

Using the marking pen, writing was performed on the coated paper to form a pink handwriting.
The handwriting has a pink color at room temperature (25 ° C.), and when it is rubbed with a friction body attached to the shaft tube, the handwriting is discolored and becomes colorless, and this state is maintained at room temperature. Then, by cooling to −30 ° C. or lower, the original pink color was restored, and the discoloration behavior was reproduced repeatedly.

Example 5
Preparation of reversible thermochromic microcapsule pigment (a) 4.0 parts of 1,3-dimethyl-6-diethylaminofluorane as component (4), 4,4 '-(2-ethylhexane-1, 1- component as component (b) Diyl) Color comprising 4.0 parts of diphenol, 6.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane, and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) A microcapsule pigment suspension containing a reversible thermochromic composition having a memory property was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 2.5 μm, a complete color erasing temperature of 60 ° C., and a complete color development temperature of −20 ° C., which changes from orange to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the microcapsule pigment (previously cooled to -20 ° C. or less to develop an orange color), 0.5 part of hydroxyethyl cellulose, a comb polymer dispersant [ Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3- ON and a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, acrylic resin emulsion [manufactured by Clariant Polymer Co., Ltd., trade name: MOBON 752, pH 7.5] 5.0 part , 0.5 part of polyvinyl alcohol, 25.0 parts of glycerin, 0.02 part of antifoaming agent, and 42.48 parts of water were mixed to obtain a reversible thermochromic aqueous ink composition.
The pH of the ink composition was 7.24.

Production of direct liquid writing instrument (see Fig. 5)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 3 (chisel) via the holder 5. Type) and the cap 6 was fitted to obtain a direct liquid writing instrument (marking pen).
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

An orange handwriting (highlight) was formed by writing on the characters printed on the coated paper using the marking pen.
The handwriting has an orange color at room temperature (25 ° C.), and when it is rubbed with a friction body attached to the shaft cylinder, the handwriting is discolored and becomes colorless, and this state is maintained at room temperature. By cooling to −20 ° C. or lower, the original pink color was restored, and the discoloration behavior was reproduced repeatedly.

Example 6
Preparation of reversible thermochromic microcapsule pigment (a) 3.0 parts of 4- [2,6-bis (2-ethoxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine as component (b) Reversible thermal discoloration having color memory consisting of 10.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) A microcapsule pigment suspension encapsulating the composition was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 2.5 μm, a complete color erasing temperature of 59 ° C., and a complete color development temperature of −20 ° C., and changes from yellow to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the microcapsule pigment (previously cooled to -20 ° C. or less to develop a yellow color), 0.5 part of hydroxyethyl cellulose, a comb polymer dispersant [ Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3- Mixture of ON and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, water-soluble urethane resin [manufactured by Avicia Co., Ltd., trade name: Neoletz R966, PH7.5,] 5.0 Part, polyvinyl alcohol 0.5 part, glycerin 25.0 parts, antifoaming agent 0.02 part, and water 42.48 parts were mixed to obtain a reversible thermochromic aqueous ink composition.
The pH of the ink composition was 7.05.

Writing instrument production (see Fig. 5)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 3 ( A chisel type) was attached and a cap 6 was fitted to obtain a direct liquid writing instrument 1 (marking pen).
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

Using the marking pen, a yellow handwriting (highlight) was formed by writing on the characters printed on the coated paper.
The handwriting has a yellow color at room temperature (25 ° C.), and when it is rubbed with a friction body attached to the shaft cylinder, the handwriting is discolored and becomes colorless, and this state is maintained at room temperature. By cooling to −20 ° C. or lower, the original yellow color was restored, and the discoloration behavior was reproduced repeatedly.

Example 7
Preparation of reversible thermochromic microcapsule pigment (a) 4.5 parts of 2- (2-chloroamino) -6-dibutylaminofluorane as component (4), 4,4 '-(2-ethylhexane- 1,1-diyl) diphenol 3.0 parts, 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane 5.0 parts, (ha) 4-benzyloxyphenylethyl caprate as component 50.0 A microcapsule pigment suspension containing a reversible thermochromic composition having color memory properties consisting of parts was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle diameter of 2.4 μm, a complete color erasing temperature of 56 ° C., a complete color development temperature of −20 ° C., and changes color from black to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the microcapsule pigment (previously cooled to -20 ° C. or less to develop a black color), 0.5 part of hydroxyethyl cellulose, a comb polymer dispersant [ Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3- Mixture of ON and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, acrylic resin emulsion [trade name: Neoacryl A-640, pH 7.5, manufactured by Avicia Co., Ltd.] 5.0 Part, polyvinyl alcohol 0.5 part, glycerin 25.0 parts, antifoaming agent 0.02 part, and water 42.48 parts were mixed to obtain a reversible thermochromic aqueous ink composition.
The pH of the ink composition was 7.00.

Writing instrument production (see Fig. 4)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 3 ( A bullet type, φ3.0) was attached, and a cap 6 was fitted to obtain a direct liquid writing instrument 1 (marking pen).
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

A black handwriting was formed by writing on the coated paper using the marking pen.
The handwriting is black at room temperature (25 ° C.), and when it is rubbed with a friction body attached to the shaft tube, the handwriting is decolored and colorless, and this state is maintained at room temperature. By cooling to −20 ° C. or lower, the original black color was restored, and the discoloration behavior was reproduced repeatedly.

Example 8
Preparation of reversible thermochromic microcapsule pigment (a) 4.5 parts of 2- (2-chloroamino) -6-dibutylaminofluorane as component (4), 4,4 '-(2-ethylhexane- 1,1-diyl) diphenol 3.0 parts, 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane 5.0 parts, (ha) 4-benzyloxyphenylethyl caprate as component 50.0 A microcapsule pigment suspension containing a reversible thermochromic composition having color memory properties consisting of parts was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 2.4 μm, a complete color erasing temperature of 56 ° C., and a complete color development temperature of −20 ° C., and changes color from black to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the microcapsule pigment (previously cooled to -20 ° C. or less to develop a black color), 0.5 part of hydroxyethyl cellulose, a comb polymer dispersant [ Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3- 4. Mixture of ON and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, water-soluble urethane resin [trade name: Leoredz R-966, pH 7.5, manufactured by Avicia Co., Ltd.] 0 parts, 0.5 parts of polyvinyl alcohol, 25.0 parts of glycerin, 0.02 parts of antifoaming agent, and 42.48 parts of water were mixed to obtain a reversible thermochromic aqueous ink composition.
The pH of the ink composition was 7.00.

Writing instrument production (see Fig. 4)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 1 ( A shell type, φ2.5) was attached, and a cap 6 was fitted to obtain a direct liquid writing instrument 1 (marking pen).
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

A black handwriting was formed by writing on the coated paper using the marking pen.
The handwriting is black at room temperature (25 ° C.), and when it is rubbed with a friction body attached to the shaft tube, the handwriting is decolored and colorless, and this state is maintained at room temperature. By cooling to −20 ° C. or lower, the original black color was restored, and the discoloration behavior was reproduced repeatedly.

Example 9
Preparation of reversible thermochromic microcapsule pigment (a) 4,5,6,7-tetrachloro-3- [4- (dimethylamino) -2-methylphenyl] -3- (1-ethyl-2-) as component 2. 2.0 parts of methyl-1H-indol-3-yl) -1 (3H) -isobenzofuranone, 4,4 ′-(2-ethylhexane-1,1-diyl) diphenol as component (b) 0 parts, 5.0 parts of 2,2-bis (4′-hydroxyphenyl) -hexafluoropropane, and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c), reversible heat having color memory A microcapsule pigment suspension containing the color-changing composition was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 2.5 μm, a complete color erasing temperature of 55 ° C., and a complete color development temperature of −20 ° C., which changes from blue to colorless according to the temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the microcapsule pigment (previously cooled to -20 ° C. or less to develop a blue color), 0.5 part of hydroxyethyl cellulose, a comb polymer dispersant [ Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3- Mixture of ON and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, acrylic resin emulsion [trade name: JONCRYL 74J, pH 8.4, manufactured by Johnson Polymer Co., Ltd.] 5.0 parts , 0.5 parts of polyvinyl alcohol, 25.0 parts of glycerin, 0.02 part of antifoaming agent, and 42.48 parts of water were mixed to obtain a reversible thermochromic aqueous ink composition.
The pH of the ink composition was 7.55.

Writing instrument production (see Fig. 6)
The ink composition 2 and the stirrer 8 (SUS-304 ferritic stainless steel ball, diameter 3 mm) are built in the shaft cylinder 4, the valve mechanism 9 is interposed, and the marking pen body 3 ( A chisel type) was attached and a cap 6 was fitted to obtain a direct liquid writing instrument 1 (marking pen).
The cap is an elastomer made of a polyester resin and serves also as a friction member.
The valve mechanism is composed of a valve seat, a valve body, and a metal spring that urges the valve body to press against the valve seat, and the valve opens with the pressure applied to the pen body during writing. is there.

A blue handwriting (highlight) was formed by writing on the characters printed on the coated paper using the marking pen.
The handwriting has a blue color at room temperature (25 ° C.), and when rubbed at the top of the cap, the handwriting is discolored and colorless, and this state is maintained at room temperature and cooled to −20 ° C. or lower. As a result, the original blue color was restored, and the discoloration behavior was reproduced repeatedly.

Example 10
Preparation of reversible thermochromic microcapsule pigment (a) 9-ethyl (3-methylbutyl) amino-spiro [12H-benzo (a) xanthene-12,1 '(3'H) isobenzofuran] -3'- as component 4.0 parts of ON, 4.0 parts of 4,4 '-(2-ethylhexane-1,1-diyl) diphenol as component (b), 2,2-bis (4'-hydroxyphenyl) -hexafluoro A microcapsule pigment suspension containing a reversible thermochromic composition having color memory composed of 6.0 parts of propane and 50.0 parts of 4-benzyloxyphenylethyl caprate as the component (c) was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 2.5 μm, a complete color erasing temperature of 60 ° C., and a complete color development temperature of −20 ° C., which changes from pink to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 10.0 parts of the above microcapsule pigment (previously cooled to −20 ° C. or less to develop a pink color), the microcapsule pigment prepared in Example 5 (previously −20 15.0 parts cooled to below ℃ and colored orange) 0.5 parts hydroxyethyl cellulose, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000] 0.5 parts Organic nitrogen sulfur compounds [made by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one Mixture] 1.0 part, acrylic resin emulsion [trade name: JONCRYL74J, pH 8.4, manufactured by Johnson Polymer Co., Ltd.] 5.0 parts, polyvinyl alcohol 0.5 Part, 25.0 parts of glycerin, 0.02 part of antifoaming agent and 42.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 7.62.

Writing instrument production (see Figure 7)
The ink composition 10 is impregnated with a polyester resin sliver covered with a synthetic resin film, impregnated with the ink composition, accommodated in a shaft cylinder 4 made of polypropylene resin, and a polyester fiber resin processing pen body 3 (cannonball) at the tip of the shaft cylinder. The mold, φ2.5) was assembled in a connected state via the holder 5, and a cap 6 was attached to obtain a filling pen 1 (marking pen).
A SEBS resin is attached as a friction member 7 to the rear end portion of the shaft cylinder.

The marking pen was used to write on the coated paper to form red letters (handwriting).
The handwriting has a red color at room temperature (25 ° C.), and when it is rubbed with a friction body attached to the shaft tube, the handwriting is discolored and becomes colorless, and this state is maintained at room temperature. By cooling to −20 ° C. or lower, the original red color was restored, and the discoloration behavior was reproduced repeatedly.

Example 11
Preparation of reversible thermochromic microcapsule pigment (I) 2- (dibutylamino) -8- (dipentylamino) -4-methyl-spiro [5H- [1] benzopyrano [2,3-g] pyrimidine-5 as component (a) , 1 ′ (3′H) -isobenzofuran] -3-one 1.0 part, (b) component 4,4 ′-(2-ethylhexane-1,1-diyl) diphenol 3.0 part, A reversible thermochromic composition having color memory consisting of 5.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) A microcapsule pigment suspension containing the product was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 2.3 μm, a complete color erasing temperature of 58 ° C., and a complete color development temperature of −20 ° C., which changes from pink to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the above microcapsule pigment (previously cooled to -20 ° C. or less to develop a pink color), 0.5 part of hydroxyethyl cellulose, comb polymer dispersant [Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000] 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3 -One and a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, acrylic resin emulsion [trade name: JONCRYL 74J, pH 8.4, manufactured by Johnson Polymer Co., Ltd.] 5.0 Parts, polyvinyl alcohol 0.5 parts, glycerin 25.0 parts, antifoaming agent 0.02 parts, water 42.48 parts are mixed to obtain a reversible thermochromic aqueous ink composition. It was.
The ink composition had a pH of 7.38.

Writing instrument production (see Fig. 8)
The ink composition 10 is impregnated with a polyester resin sliver covered with a synthetic resin film, impregnated with the ink composition, accommodated in a shaft cylinder 4 made of polypropylene resin, and a polyester fiber resin processing pen body 3 (cannonball) at the tip of the shaft cylinder. A mold, φ3.0) was assembled in a connected state via a holder 5, and a cap 6 was attached to obtain a filling pen (marking pen).
The cap is formed by attaching SEBS resin as the friction member 7.

The marking pen was used to write on the coated paper to form pink letters (handwriting).
The handwriting has a pink color at room temperature (25 ° C.). When the handwriting is rubbed with a friction body attached to the shaft tube, the handwriting is discolored and becomes colorless, and this state is maintained at room temperature. Then, by cooling to −20 ° C. or lower, the original pink color was restored, and the discoloration behavior was reproduced repeatedly.

Example 12
Preparation of reversible thermochromic microcapsule pigment (a) 3.0 parts of 4- [2,6-bis (2-ethoxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine as component (b) Reversible thermal discoloration having color memory consisting of 10.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) A microcapsule pigment suspension encapsulating the composition was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has an average particle size of 2.5 μm, a complete color erasing temperature of 59 ° C., and a complete color development temperature of −20 ° C., and changes from yellow to colorless according to temperature change.

Preparation of reversible thermochromic water-based ink composition 25.0 parts of the microcapsule pigment (previously cooled to -20 ° C. or less to develop a yellow color), 0.5 part of hydroxyethyl cellulose, a comb polymer dispersant [ Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts, organic nitrogen sulfur compound [Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazoline-3- Mixture of ON and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, water-soluble urethane resin [trade name: Neoletz R966, pH 7.5, manufactured by Avicia Co., Ltd.] 5.0 parts , 0.5 part of polyvinyl alcohol, 25.0 parts of glycerin, 0.02 part of antifoaming agent, and 42.48 parts of water were mixed to obtain a reversible thermochromic aqueous ink composition.
The pH of the ink composition was 7.02.

Writing instrument production (see Fig. 9)
The ink composition 10 is impregnated with a polyester sliver covered with a synthetic resin film, impregnated with the ink composition, accommodated in a shaft cylinder 4 made of polypropylene resin, and a polyester fiber resin processing pen body 3 (chisel) at the tip of the shaft cylinder. A mold) was assembled in a connected state via a holder 5, and a cap 6 was attached to obtain a filling pen (marking pen).
The cap is an elastomer made of a polyester resin and serves also as a friction member.

A yellow handwriting (highlight) was formed by writing on the characters printed on the coated paper using the marking pen.
The handwriting has a yellow color at room temperature (25 ° C.), and when rubbed at the top of the cap, the handwriting is decolored and colorless, and this state is maintained at room temperature and cooled to −20 ° C. or lower. As a result, the original yellow color was restored, and the discoloration behavior was reproduced repeatedly.

Comparative Example 1
Preparation of reversible thermochromic water-based ink composition 25.0 parts of reversible thermochromic microcapsule pigment prepared in Example 1 (previously cooled to -20 ° C. or less to develop a pink color), hydroxyethylcellulose, 0. 5 parts, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, Mixture of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, 0.5 part of polyvinyl alcohol, 25.0 parts of glycerin, antifoam 0.02 part of the agent and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 7.00.

Preparation of writing instrument A direct liquid type writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 1.

Comparative Example 2
Preparation of reversible thermochromic aqueous ink composition 25.0 parts of the reversible thermochromic microcapsule pigment prepared in Example 2 (previously cooled to -23 ° C. or less to develop a pink color), hydroxyethyl cellulose, 0. 5 parts, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, Mixture of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, 0.5 part of polyvinyl alcohol, 25.0 parts of glycerin, antifoam 0.02 part of the agent and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 7.00.

Preparation of a formula writing instrument A direct liquid type writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 2.

Comparative Example 3
Preparation of reversible thermochromic water-based ink composition 25.0 parts of reversible thermochromic microcapsule pigment prepared in Example 3 (previously cooled to -25 ° C. or less to develop a pink color), hydroxyethylcellulose, 0. 5 parts, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, Mixture of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, 0.5 part of polyvinyl alcohol, 25.0 parts of glycerin, antifoam 0.02 part of the agent and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 7.00.

Production of Writing Instruments A direct liquid writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 3.

Comparative Example 4
Preparation of reversible thermochromic water-based ink composition 25.0 parts of reversible thermochromic microcapsule pigment prepared in Example 4 (previously cooled to -30 ° C. or less to develop a pink color), hydroxyethylcellulose, 0. 5 parts, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, Mixture of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, 0.5 part of polyvinyl alcohol, 25.0 parts of glycerin, antifoam 0.02 part of the agent and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 7.00.

Production of Writing Instruments A direct liquid writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 4.

Comparative Example 5
Preparation of reversible thermochromic water-based ink composition 25.0 parts of reversible thermochromic microcapsule pigment prepared in Example 5 (previously cooled to -20 ° C. or less and colored orange), hydroxyethylcellulose 0.5 Part, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2 -Mix-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one mixture] 1.0 part, polyvinyl alcohol 0.5 part, glycerin 25.0 parts, antifoaming agent 0.02 part and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 6.90.

Production of Writing Instruments A direct liquid writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 5.

Comparative Example 6
Preparation of reversible thermochromic water-based ink composition 25.0 parts of the reversible thermochromic microcapsule pigment prepared in Example 6 (previously cooled to -20 ° C. or less and colored black), hydroxyethylcellulose 0.5 Part, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2 -Mix-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one mixture] 1.0 part, polyvinyl alcohol 0.5 part, glycerin 25.0 parts, antifoaming agent 0.02 part and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 7.05.

Production of Direct Liquid Writing Instruments Built in the same writing instrument as Example 6, a direct liquid writing instrument (marking pen) was obtained.

Comparative Example 7
Preparation of reversible thermochromic water-based ink composition 25.0 parts of the reversible thermochromic microcapsule pigment prepared in Example 7 (previously cooled to -20 ° C. or less and colored black), hydroxyethylcellulose 0.5 Part, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2 -Mix-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one mixture] 1.0 part, polyvinyl alcohol 0.5 part, glycerin 25.0 parts, antifoaming agent 0.02 part and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 7.10.

Production of Writing Instruments A direct liquid writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 7.

Comparative Example 8
Preparation of reversible thermochromic water-based ink composition 25.0 parts of the reversible thermochromic microcapsule pigment prepared in Example 8 (previously cooled to -20 ° C. or less and colored black), hydroxyethylcellulose 0.5 Part, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2 -Mix-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one mixture] 1.0 part, polyvinyl alcohol 0.5 part, glycerin 25.0 parts, antifoaming agent 0.02 part and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 6.90.

Production of Writing Instruments A direct liquid writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 8.

Comparative Example 9
Preparation of reversible thermochromic water-based ink composition 25.0 parts of reversible thermochromic microcapsule pigment prepared in Example 9 (previously cooled to -20 ° C. or less to develop a blue color), hydroxyethylcellulose 0.5 Part, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2 -Mix-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one mixture] 1.0 part, polyvinyl alcohol 0.5 part, glycerin 25.0 parts, antifoaming agent 0.02 part and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 6.90.

Preparation of writing instrument A direct liquid writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 9.

Comparative Example 10
Preparation of reversible thermochromic water-based ink composition Reversible thermochromic microcapsule pigment prepared in Example 10 (previously cooled to -20 ° C. or less and colored in pink) 10.0 parts, in Example 5 15.0 parts of the reversible thermochromic microcapsule pigment prepared (previously cooled to −20 ° C. or lower and colored orange), 0.5 part of hydroxyethyl cellulose, comb polymer dispersant [Nippon Lubrizol Co., Ltd. ), Trade name: Solsperse 43000], 0.5 parts, organic nitrogen sulfur compound [made by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2-methyl-4-isothiazolin-3-one and 5-chloro Mixture of 2-methyl-4-isothiazolin-3-one] 1.0 part, 0.5 part polyvinyl alcohol, 25.0 parts glycerin, 0.02 part antifoaming agent and 47.48 parts water. Thus, a reversible thermochromic water-based ink composition was obtained.
The pH of the ink composition was 6.90.

Production of Writing Instruments A direct liquid writing instrument (marking pen) was obtained by being incorporated in the same writing instrument as in Example 10.

Comparative Example 11
Preparation of reversible thermochromic water-based ink composition 25.0 parts of the reversible thermochromic microcapsule pigment prepared in Example 11 (previously cooled to -20 ° C. or less to develop a pink color), hydroxyethylcellulose, 0. 5 parts, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, Mixture of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one] 1.0 part, 0.5 part of polyvinyl alcohol, 25.0 parts of glycerin, antifoam 0.02 part of the agent and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 6.96.

Preparation of writing instrument A writing instrument (marking pen) filled in was obtained by being built in the same writing instrument as in Example 11.

Comparative Example 12
Preparation of reversible thermochromic aqueous ink composition 25.0 parts of the reversible thermochromic microcapsule pigment prepared in Example 12 (previously cooled to -20 ° C. or less to develop yellow color), hydroxyethylcellulose 0.5 Part, comb polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solsperse 43000], 0.5 parts of organic nitrogen sulfur compound [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R-150, 2 -Mix-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one mixture] 1.0 part, polyvinyl alcohol 0.5 part, glycerin 25.0 parts, antifoaming agent 0.02 part and 47.48 parts of water were mixed to obtain a reversible thermochromic water-based ink composition.
The pH of the ink composition was 6.98.

Preparation of writing instrument A writing instrument (marking pen) filled in was obtained by being built in the same writing instrument as in Example 12.

Handwriting Adhesion Test Using the writing tools prepared in Examples 1 to 12 and Comparative Examples 1 to 12, circle writing was performed on coated paper (mirror coated paper).
The handwriting is sufficiently dried by leaving it at room temperature (25 ° C.) for 1 hour, and the handwriting is decolored by rubbing with a friction member (SEBS resin).
The erased handwriting was cooled to below the complete coloring temperature to develop the handwriting and compared with the handwriting before erasure.

Vibration Test Using a writing instrument produced in Examples 1 to 12 and Comparative Examples 1 to 12, 10 lines of 20 cm are written on a report sheet.
Put the cap on the writing instrument and set it upright on the shaker (manufactured by Taitec Co., Ltd., reciprocating shaker) in the upright state (writing tip upward), and add vibration in the vertical direction at 284 rpm for 5 hours in an environment of 25 ° C. After that, 10 lines of 20 cm straight lines were written on the report paper and compared with the handwriting before the test.

The adhesion test and vibration test results are shown in the following table.

Evaluation regarding symbols in the table of the adhesion test is as follows.
○: Handwriting almost similar to that before erasure.
X: The handwriting is peeled off compared to before erasure.

Evaluation of symbols in the vibration test table is as follows.
○: The handwriting is not faint compared to the initial, and has the same color density as the initial.
X: Fading was observed at the start of writing, and the handwriting density was lighter than in the initial stage.

t ₁ Complete color development temperature of reversible thermochromic microcapsule pigment with heat decoloring type t ₂ Color development start temperature of reversible thermochromic microcapsule pigment with heat decoloration type t ₃ Reversible thermochromic microcapsule pigment with heat decoloration type Decoloration start temperature of t ₄ Complete decolorization temperature of reversible thermochromic microcapsule pigment of heat decoloring type T ₁ Complete decoloration temperature of reversible thermochromic microcapsule pigment of ₁ heating color developing type T ₂ Reversible heat of color developing type of heat decoloring type Discoloration start temperature of the color-changing microcapsule pigment T ₃ Color development start temperature of the reversible thermochromic microcapsule pigment of the ₃ heating color development type T ₄ Color development temperature of the reversible thermochromic microcapsule pigment of the heat development color type ΔH Hysteresis width 1 Writing instrument 2 Ink composition 3 Pen body 4 Shaft cylinder 5 Holder 6 Cap 7 Friction member 8 Stirring body 9 Valve mechanism 10 Ink occlusion body

Claims (8)

  Encapsulating a reversible thermochromic composition comprising water and (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction occurs. Reversible thermochromic microcapsule pigment, polymer flocculant, comb polymer dispersant having a carboxyl group in the side chain, organic nitrogen sulfur compound, dispersion stabilizer, and polyurethane having a pH of 5 to 9 A reversible thermochromic aqueous ink composition comprising an emulsion or an acrylic resin emulsion, wherein the pH of the ink composition is in the range of 5-8.   The organic nitrogen sulfur compound is 2- (4-thiazoyl) -benzimidazole, 2- (thiocyanatomethylthio) -1,3-benzothiazole, 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl The reversibly thermochromic water-based ink composition according to claim 1, which is a compound selected from -4-isothiazolin-3-one.   The reversible thermochromic water-based ink composition according to claim 1 or 2, wherein the mass ratio of the comb polymer dispersant having a carboxyl group in the side chain and the organic nitrogen sulfur compound is 1: 1 to 1:10.   The reversible thermochromic aqueous ink composition according to any one of 1 to 3, wherein the dispersion stabilizer is a water-soluble resin that is soluble in a pH range of 5 to 8.   A writing instrument comprising a pen body that houses the reversible thermochromic water-based ink composition according to any one of claims 1 to 4 in a shaft cylinder and derives the ink composition in the shaft cylinder.   The writing instrument according to claim 5, wherein the pen body is a marking pen body.   The writing instrument according to claim 5 or 6, comprising a friction member.   A writing instrument set comprising the writing instrument according to any one of claims 5 to 7 and a friction body.

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