JP4921189B2 - Reversible thermochromic water-based ink composition and direct liquid writing instrument incorporating the same - Google Patents

Description

  The present invention relates to a reversible thermochromic water-based ink composition and a direct liquid writing instrument incorporating the same.

Conventionally, a reversible thermochromic water-based ink composition capable of forming a handwriting whose color changes with temperature change and a writing instrument incorporating the same have been disclosed (for example, see Patent Document 1).
In order to suppress aggregation and sedimentation of the reversible thermochromic microcapsule pigment contained in the ink composition and to prevent lightening of the handwriting, a polymer flocculant is added to the ink so that the microcapsule pigment particles are not dispersed. It is a type that produces a loose bridging action, and is a type in which an ink occlusion body consisting of a fiber bundling body is accommodated in a shaft cylinder, and the ink occlusion body is impregnated with ink, so-called filling-type writing instruments. It is intended.
However, even if the ink composition is applied to a filling-type writing instrument, the specific gravity difference between the reversible thermochromic microcapsule pigment and the vehicle cannot be completely controlled by the addition of the polymer flocculant. It is difficult to completely suppress the aggregation and sedimentation of the discolorable microcapsule pigment. In particular, if the writing tip part is left facing upward (upright state) for a long time, the microcapsule pigment will settle in the ink occlusion body and Light coloration may occur.
In addition, since the microcapsule pigment has a low color density compared to general dyes and pigments, a method of increasing the ink outflow amount to obtain a handwriting with a desired color density can be considered. The writing instrument is difficult to increase the amount of ink outflow due to its structure.
JP-A-11-335613

  The present invention is intended to solve the problems of the conventional reversible thermochromic water-based ink composition and the writing instrument incorporating the same, without causing lightening of handwriting when writing after a period of time, The handwriting has a good color density and is intended to provide a reversible thermochromic water-based ink composition suitable for a writing instrument of a type containing an agitator that stirs ink in a shaft cylinder and a direct liquid writing instrument incorporating the ink composition. Is.

The present invention is an ink composition incorporated in a direct liquid writing instrument containing a stirring body for stirring ink in a shaft cylinder, wherein the ink composition is (i) an electron-donating color-forming organic compound, ( (B) an electron-accepting compound, (c) a reversible thermochromic microcapsule pigment encapsulating a reversible thermochromic composition comprising a reaction medium that determines the occurrence temperature of the color reaction of the two, and the reversible thermochromic micro The capsule pigment is composed of microcapsule particles having different specific gravities and a vehicle containing water and a polymer flocculant, and the components encapsulated in the microcapsule particles are encapsulated in the reversible thermochromic microcapsule pigment. accepting compound and (iii) a reaction medium determining the occurrence temperature of color reaction of the both bi between the specific gravity of the microcapsule particles during color development of the reversible thermal discoloration microcapsule pigment A reversible thermochromic water-based ink composition having a specific gravity of Kuru, or an ink composition incorporated in a direct liquid writing instrument containing a stirrer for stirring ink in a shaft cylinder, wherein the ink composition is (B) Reversible heat encapsulating a reversible thermochromic composition comprising a reaction medium that determines the temperature at which the color reaction of both occurs (b) an electron-donating color-forming organic compound; The color-changing microcapsule pigment, the reversible thermochromic microcapsule pigment are composed of microcapsule particles having different specific gravity, and a vehicle containing water and a polymer flocculant, and the components contained in the microcapsule particles are reversible heat. enclosed in the discoloration microcapsule pigment (b) is a reaction medium which determines the occurrence temperature of the electron-accepting compound and (iii) the two color reaction, the reversible thermal discoloration microcapsule pigment Gravity during color (X), the specific gravity of the microcapsule particles (Y), a specific gravity (Z) is the formula of vehicle (1) and a reversible thermal discoloration aqueous ink composition satisfying (2), or,
Z + 0.02 ≦ X ≦ Z + 0.2 (1)
Z−0.25 ≦ Y ≦ Z−0.03 (2)
An ink composition incorporated in a direct liquid writing instrument containing a stirring body for stirring ink, wherein the ink composition comprises (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, C) A reversible thermochromic microcapsule pigment encapsulating a reversible thermochromic composition comprising a reaction medium that determines the temperature at which the color reaction of the two occurs, and the reversible thermochromic microcapsule pigment having different specific gravity (B) an electron-accepting compound, and (c) the above-mentioned components encapsulated in a reversibly thermochromic microcapsule pigment comprising capsule particles and a vehicle containing water and a polymer flocculant. a reaction medium which determines the occurrence temperature of both the color reaction, the reversible thermal discoloration microcapsule pigment density at color development (X), the ratio of the specific gravity (Y), vehicle of the microcapsule particles (Z) is a requirement equation (3) and (4) Reversible thermochromic ink composition for a writing instrument satisfying.
Z−0.25 ≦ X ≦ Z−0.03 (3)
Z + 0.02 ≦ Y ≦ Z + 0.2 (4)
Is a requirement.
Furthermore, prior SL comprises a water-soluble organic solvent in the vehicle, and, the specific gravity of the water-soluble organic solvent is 1.1 or more, and the like that the viscosity of the ink is in the range of 2 to 20 mPa · s As a requirement.
Furthermore, a direct liquid writing instrument comprising the reversible thermochromic water-based ink composition together with a stirrer is a requirement.
Furthermore, it has a valve mechanism in the shaft cylinder, the valve mechanism is a mechanism that opens the valve by pressing the pen body provided at the writing tip, and the writing pressure on the pen body at the time of writing. The requirement is that the valve is a mechanism that opens, and that the pen body is a marking pen body.

  The present invention is a writing instrument that contains a stirrer that stirs ink in a shaft cylinder that can always form a good handwriting without fading the handwriting obtained by writing after the passage of time and that also improves the color density of the handwriting. A suitable reversible thermochromic aqueous ink composition and a direct liquid writing instrument containing the ink composition can be provided.

The reversible thermochromic microcapsule pigment comprises (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a three-component reaction medium that determines the temperature at which the color reaction occurs. In a microcapsule, a reversible thermochromic composition containing at least the above is encapsulated in a microcapsule. Those described in Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, and the like can be used.
The microcapsule pigment discolors before and after a predetermined temperature (discoloration point), exhibits a decolored state in a temperature range above the complete decolorization temperature, and exhibits a color development state in a temperature range below the complete color development temperature. Of these, only one specific state exists at room temperature. That is, the other state is maintained while the heat or cold necessary to develop the state is applied, but when the heat or cold is no longer applied, the state returns to the state exhibited in the normal temperature range. The width is relatively small (ΔH _A = 1-7 ° C.) (see FIG. 1).

前記エステル化合物は、分子内に芳香環を２個有するアルコール化合物と、炭素数４以上の飽和又は不飽和脂肪酸とから構成されるエステル化合物である。
式中のＲは炭素数４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６〜２０のアルキル基、更に好ましくは炭素数８〜１８のアルキル基である。
前記化合物として具体的には、ブタン酸−４−ベンジルオキシフェニルエチル、ペンタン酸−４−ベンジルオキシフェニルエチル、ヘキサン酸−４−ベンジルオキシフェニルエチル、ヘプタン酸−４−ベンジルオキシフェニルエチル、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、ノナデカン酸−４−ベンジルオキシフェニルエチル、エイコサン酸−４−ベンジルオキシフェニルエチル、トリコサン酸−４−ベンジルオキシフェニルエチル、テトラコサン酸−４−ベンジルオキシフェニルエチル、ペンタコサン酸−４−ベンジルオキシフェニルエチル、ヘキサコサン酸−４−ベンジルオキシフェニルエチル、ヘプタコサン酸−４−ベンジルオキシフェニルエチル、オクタコサン酸−４−ベンジルオキシフェニルエチル、ノナコサン酸−４−ベンジルオキシフェニルエチル、トリアコンタン酸−４−ベンジルオキシフェニルエチル、ヘントリアコンタン酸−４−ベンジルオキシフェニルエチルを例示できる。 In addition, 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 ). There is also a heat decolorable microcapsule pigment in which a reversible thermochromic composition capable of storing and retaining colors in a temperature range between t _{2 and} t ₃ (substantially two-phase holding temperature range) is encapsulated in microcapsules. Applicable (Figure Reference).
In addition, as the heat-decolorable microcapsule pigment capable of storing and retaining color, when the ester compound represented by the general formula (A) is used as the component (c), a wide hysteresis width (ΔH _B = 40 with respect to the color density-temperature curve) ˜70 ° C.) and discoloration is preferable.
In order to allow only one of the states before and after the color change to exist in the normal temperature range, the hysteresis width is 40 to 70 ° C., preferably 50 to 70 ° C., more preferably 60 to 70 ° C. The color temperature (t ₄ ) is 45 ° C. or higher, preferably 50 ° C. or higher, and the color development start temperature (t ₂ ) is 0 ° C. or lower, preferably −5 ° C. or lower.

The ester compound is an ester compound composed of an alcohol compound having two aromatic rings in the molecule and a saturated or unsaturated fatty acid having 4 or more carbon atoms.
R in the formula represents an alkyl group or alkenyl group having 4 or more carbon atoms, preferably an alkyl group having 6 to 20 carbon atoms, more preferably an alkyl group having 8 to 18 carbon atoms.
Specific examples of the compound include butanoic acid-4-benzyloxyphenylethyl, pentanoic acid-4-benzyloxyphenylethyl, hexanoic acid-4-benzyloxyphenylethyl, heptanoic acid-4-benzyloxyphenylethyl, and octanoic acid. -4-benzyloxyphenylethyl, nonanoic acid-4-benzyloxyphenylethyl, decanoic acid-4-benzyloxyphenylethyl, undecanoic acid-4-benzyloxyphenylethyl, dodecanoic acid-4-benzyloxyphenylethyl, tridecanoic acid -4-benzyloxyphenylethyl, tetradecanoic acid-4-benzyloxyphenylethyl, pentadecanoic acid-4-benzyloxyphenylethyl, hexadecanoic acid-4-benzyloxyphenylethyl, heptadecanoic acid-4-benzylo Cyphenylethyl, octadecanoic acid-4-benzyloxyphenylethyl, nonadecanoic acid-4-benzyloxyphenylethyl, eicosanoic acid-4-benzyloxyphenylethyl, tricosanoic acid-4-benzyloxyphenylethyl, tetracosanoic acid-4-benzyl Oxyphenylethyl, pentacosanoic acid-4-benzyloxyphenylethyl, hexacosanoic acid-4-benzyloxyphenylethyl, heptacosanoic acid-4-benzyloxyphenylethyl, octacosanoic acid-4-benzyloxyphenylethyl, nonacosanoic acid-4-benzyl Examples thereof include oxyphenyl ethyl, triacontanoic acid-4-benzyloxyphenylethyl, and hentriacontanoic acid-4-benzyloxyphenylethyl.

Furthermore, specific alkoxyphenol compounds having a linear or side chain alkyl group having 3 to 18 carbon atoms as an electron-accepting compound (Japanese Patent Laid-Open Nos. 11-129623 and 11-5973), a specific hydroxybenzoic acid A heat-colorable microcapsule pigment using an ester (Japanese Patent Laid-Open No. 2001-105732), a gallic acid ester (Japanese Patent Publication No. 51-44706, Japanese Patent Laid-Open No. 2003-253149), or the like can also be applied (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, but the component ratio that generally provides the desired color change characteristics is (B) Component 1 is in the range of (b) Component 0.1-50, preferably 0.5-20, (c) Component 1-800, preferably 5-200. Parts by weight).
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 microcapsule pigment may have a circular cross section or a non-circular cross section.
The average particle size of the microcapsule pigment is 0.5 to 5.0 μm, preferably 0.5 to 3 μm, more preferably 1 to 3 μm.
When the average particle diameter exceeds 5.0 μm, the ink outflow property is lowered and the fixing property to the writing surface is liable to be lowered. On the other hand, when the average particle size is less than 0.5 μm, it is difficult to exhibit high density color development.
In addition, when the ratio of the reversible thermochromic composition to the microcapsule wall film increases, the wall film becomes too thin, causing a decrease in resistance to pressure and heat, and conversely, the reversible thermochromic composition of the wall film. When the ratio to is increased, the color density and sharpness at the time of color development are unavoidable, and therefore, reversible thermochromic composition / wall film = 6/1 to 1/1 (weight ratio) is preferable.

  The microencapsulation of the reversible thermochromic composition includes interfacial polymerization method, interfacial polycondensation method, in situ polymerization method, coacervate method, submerged curing coating method, phase separation method from aqueous solution, phase separation method from organic solvent Further, means such as a melt dispersion cooling method, an air suspension coating method, and a spray drying method can be applied. 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 reversible thermochromic microcapsule pigment can be blended in an amount of 5 to 40% by weight, preferably 10 to 40% by weight, more preferably 10 to 30% by weight, based on the total amount of the ink composition.
If it is less than 5% by weight, the color density is insufficient, and if it exceeds 40% by weight, the ink outflow is reduced and writing performance is hindered.

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.
As the polymer flocculant, a nonionic water-soluble polymer is used, 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, nonionic water-soluble cellulose derivatives, etc. Specific examples of nonionic water-soluble cellulose derivatives include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxy Examples include ethyl methyl cellulose and hydroxypropyl methyl cellulose.
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.

  In addition, benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin and other rust preventives, coalic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, dehydro as necessary Preservatives or antifungal agents such as sodium acetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine, urea, nonionic surfactants, reduced or non- Reduced starch hydrolyzate, disaccharides such as trehalose, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbit, mannitol, sodium pyrophosphate and other wetting agents, antifoaming agents, dispersants, ink permeability Fluorosurfactant to improve It may be used anion surfactant.

There is a specific gravity difference between the reversible thermochromic microcapsule pigment and a vehicle comprising at least water and a polymer flocculant, and the specific gravity (during color development) of the reversible thermochromic microcapsule pigment is greater than the specific gravity of the vehicle. Then, the pigment easily settles with time, and the precipitate becomes a hard cake, resulting in poor redispersibility. On the contrary, if the specific gravity (at the time of color development) of the reversible thermochromic microcapsule pigment is smaller than the specific gravity of the vehicle, the pigment tends to float over time, and the suspended matter becomes a hard cake, resulting in poor redispersibility.
The present invention solves the above-mentioned problems by adding microcapsule particles having a specific gravity different from that of the reversible thermochromic microcapsule pigment, and the specific gravity of the reversible thermochromic microcapsule pigment is greater than the specific gravity of the vehicle. Uses microcapsule particles having a specific gravity smaller than that of the vehicle. Further, when the specific gravity of the reversible thermochromic microcapsule pigment is smaller than the specific gravity of the vehicle, microcapsule particles having a larger specific gravity than the vehicle are used.
In other words, the specific gravity of the vehicle exists between the specific gravity of the reversible thermochromic microcapsule pigment during color development and the specific gravity of the microcapsule particles.
By adding such a microcapsule particle children, mixed microcapsules aggregate (reversible thermal discoloration microcapsule pigment, aggregates of microcapsules grains child) is, difference in specific gravity is adjusted to a specific gravity near the vehicle As a result, it becomes difficult to separate in ink, and can be easily redispersed even if separated.

The microcapsule particles have the same capsule form as the reversible thermochromic microcapsule pigment, and the specific gravity can be changed depending on the type of inclusion.
The inclusions, various liquid material, a liquid-like body and may be a solid, combination of the liquid and gas.
Incidentally, as the inclusions, Ru using a reaction medium which determines the occurrence temperature of the reversible thermal discoloration microcapsule is contained in the pigment (B) an electron accepting compound and (iii) color reactions of the both.
The microcapsule particle child ink composition relative to the total amount, 2 to 20 wt%, preferably 5 to 20 wt%, more preferably be formulated 5-15% by weight.
If it is less than 2% by weight, the effect of adjusting the specific gravity is insufficient, and if it exceeds 15% by weight, the balance of specific gravity may be impaired.

In the relationship between the specific gravity at the time of color development of the reversible thermochromic microcapsule pigment, the specific gravity of the microcapsule particles, and the specific gravity of the vehicle, the relationship of the formulas (1) and (2), or the formulas (3) and (4) By satisfying this relationship, it is possible to further prevent the microcapsule pigment from separating in the ink and making the handwriting thin, or the hard dispersion to impair the redispersibility.
Formula (1) is Z + 0.02 <= X <= Z + 0.2, Preferably it is Z + 0.02 <= X <= Z + 0.15, More preferably, it is Z + 0.03 <= X <= Z + 0.1.
Formula (2) is Z-0.25 <= Y <= Z-0.03, Preferably it is Z-0.2 <= Y <= Z-0.03, More preferably, Z-0.15 <= Y <= Z--. 0.03.
On the other hand, Formula (3) is Z-0.25 <= X <= Z-0.03, Preferably it is Z-0.2 <= X <= Z-0.3, More preferably, Z-0.15 <= X <= 0.3. Z-0.03.
Formula (4) is Z + 0.02 <= Y <= Z + 0.2, Preferably it is Z + 0.02 <= Y <= Z + 015, More preferably, it is Z + 0.03 <= Y <= Z + 0.1.

  Further, the viscosity of the ink is 2 to 20 mPa · s (20 ° C.), preferably 2 to 10 mPa · s. If the viscosity exceeds 20 mPa · s, the ink outflow may be reduced and the handwriting may be faded or interrupted. is there.

The ink composition is put into practical use by containing a stirring body for stirring ink in a shaft cylinder and directly storing it in a writing instrument such as a marking pen, a writing pen, or a ballpoint pen with a pen attached to a writing tip.
Examples of the marking pen body include pen bodies such as fiber chips, felt chips, and plastic chips.
As a brush pen body, a fiber bundling body in which fibers are bundled closely in the longitudinal direction, a plastic porous body having continuous pores, a heat-bonded or resin processed body of synthetic resin fibers, an extrusion molding process of a soft resin or an elastomer The body is mentioned.
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 tip is 0.3 to 2.0 mm, preferably 0.4 to 1.5 mm, more preferably 0.5 to 0.5 mm in outer diameter of cemented carbide, stainless steel, ruby, ceramic, or the like. A 1.0 mm ball is effective.
The ballpoint pen tip is provided with a resilient member for projecting the rear end of the ball forward in the tip. When not writing, the ball is pressed against the inner edge of the tip of the tip to bring it into close contact, and when writing, it is The ball can be retracted so that ink can flow out.

A transparent molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon is preferably used for the shaft cylinder that stores the ink.
The transparency of the cylinder includes colored transparency, translucency, and colored translucency, and the ink color and remaining ink amount can be confirmed.

The shaft cylinder contains a stirrer that shakes the writing instrument and stirs the ink when the ink settles or floats.
The shape and material of the stirrer are not particularly limited. Examples of the shape include a spherical shape and a rod shape. Examples of the material include metals, plastics, glass, stone materials, ceramics, metal-coated surfaces, and metals. For example, the surface is plated.

A configuration in which a valve mechanism is arranged in the shaft cylinder of the writing instrument and ink in the shaft cylinder is led out to the pen body by opening the valve is preferable.
The valve mechanism includes a structure including a valve seat, a valve (valve rod), and an elastic member (coil spring) that urges the valve in the valve closing direction.
Examples of the means for opening the valve include a structure in which the valve is opened by pressing a knock portion provided at the rear end of the shaft cylinder, and a structure in which the valve is opened by pressing the pen body.
In the case of a structure in which the valve is opened by pressing the pen body, because the valve is opened by the pressure applied to the pen body at the time of writing, the ink is led out together with the writing, so the operation of pressing the pen body can be omitted. Is preferred.

The handwriting formed from the direct liquid writing instrument containing the ink composition can be discolored by rubbing with a finger, heating, or application of a cooling / heating tool.
Examples of the heating means include a heating color changer equipped with a resistance heating element, a heating color changer filled with warm water, and a hair dryer. Preferably, a scraping member is used as a means capable of changing color by a simple method. Used.
As the rubbing member, an elastic body such as an elastomer or plastic foam which is rich in elasticity and can generate frictional heat by rubbing at the time of rubbing is preferable, but a plastic molded body, stone material, wood, Metals and fabrics may be used.
Although it is possible to scrape the handwriting by using an eraser, it is preferable to use a rubbing member as described above because erase scraps are generated at the time of rubbing.
As the material of the rubbing member, silicone resin or SEBS resin (styrene ethylene butadiene styrene block copolymer) is preferably used. However, the silicone resin easily adheres to the portion erased by rubbing, and when repeatedly written. Since the handwriting tends to be repelled, SEBS resin is more preferably used.
The scraping member may be a member having an arbitrary shape that is separate from the writing instrument, but is excellent in portability by being fixed to the writing instrument.
Examples of the location where the rubbing member is fixed include a cap tip (top) or a shaft cylinder rear end (portion where no writing tip is provided).
Furthermore, it is also possible to provide a small protrusion of any shape on a part of the cap or a part of the shaft tube to make a scraping member.
Examples of the cooling means include a cold / hot color changing tool using a Peltier element, a cold / hot color changing tool filled with a refrigerant such as cold water and ice pieces, a refrigerator and a freezer.

Examples of the present invention are shown below, but the present invention is not limited thereto.
In addition, the part in an Example shows a weight part.
Example 1
Preparation of reversible thermochromic microcapsule pigment (a) 4,5,6,7-tetrachloro-3- [4- (dimethylamino) -2-ethoxyphenyl] -3- (1-ethyl-2-) as component Methyl-1H-indol-3-yl) 1 (3H) -isobenzofuranone 1.5 parts, (ro) component 4,4 '-(2-methylpropylidene) bisphenol 3.0 parts, 2,2- A reversible thermochromic composition comprising 5.0 parts of bis (4'-hydroxyphenyl) hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as the component (c) is uniformly heated and dissolved, A solution prepared by mixing 25.0 parts of an aromatic polyvalent isocyanate prepolymer and 50.0 parts of a co-solvent as a film material is emulsified and dispersed in fine water droplets in an 8% aqueous polyvinyl alcohol solution at about 70 ° C. After continued stirring time, added 2.5 parts of a water-soluble aliphatic modified amine to give the reversible thermal discoloration microcapsule pigment suspension and stirring was further continued for 6 hours.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a specific gravity of 1.08, 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. The color changes from blue to colorless as the temperature changes. To do.

Preparation of microcapsule particles From 3.0 parts of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane, 3.0 parts of 1,1-bis (4-hydroxyphenyl) decane and 50.0 parts of stearyl caprate The resulting composition is uniformly heated and dissolved, and a solution obtained by mixing 25.0 parts of an aromatic polyisocyanate prepolymer and 50.0 parts of a co-solvent as a wall film material is formed into fine droplets in an 8% aqueous polyvinyl alcohol solution. After emulsifying and dispersing as described above, stirring was continued at 70 ° C. for about 1 hour, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a microcapsule particle suspension.
The suspension was centrifuged to isolate microcapsule particles.
The microcapsule particles had a specific gravity of 0.97 and an average particle diameter of 2.5 μm.

Preparation of reversible thermochromic water-based ink composition 13.0 parts of the reversible thermochromic microcapsule pigment, 7.0 parts of microcapsule particles, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: CELLOSIZE WP-09B] 0.5 part, 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1% diluted phosphoric acid solution 0.1 Part was added and stirred uniformly to obtain a reversible thermochromic aqueous ink composition.
The specific gravity of the vehicle (ink component excluding reversible thermochromic microcapsule pigment and microcapsule particles) in the ink was 1.03.

Preparation of direct liquid type writing instrument The above-mentioned ink (previously cooled to −20 ° C. or less to cause the microcapsule pigment to develop a blue color and left at room temperature) and a stirrer (3 mm diameter metal sphere) The marking pen body [chisel type fiber pen body (porosity of about 53%)] was attached to the tip portion with a valve mechanism interposed therein 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 rubbing member to the rear portion of the shaft cylinder of the direct liquid writing instrument.

A blue character (handwriting) was formed by writing on the paper using the writing instrument.
The handwriting has a blue color at room temperature (25 ° C.). When the character is abraded with a scraping member attached to the cap, the character is discolored and becomes colorless, and this state is maintained at room temperature. Then, by cooling to −20 ° C. or lower, the original blue color was restored, and the discoloration behavior was reproduced repeatedly.

Example 2
2. Preparation of reversible thermochromic microcapsule pigment (a) 2.5 parts of 1,3-dimethyl-6-diethylaminofluorane as component (4), 4,4 '-(2-methylpropylidene) bisphenol as component (3) Uniform reversible thermochromic composition comprising 0 parts, 5.0 parts of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane, and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) Is dissolved in water, and emulsified and dispersed in a solution of 25.0 parts of aromatic polyisocyanate prepolymer and 50.0 parts of co-solvent as a wall film material in 8% polyvinyl alcohol aqueous solution so as to form fine droplets. After stirring at 70 ° C. for about 1 hour, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was continued for another 6 hours to obtain a reversible thermochromic microcapsule pigment suspension. It was.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a specific gravity of 1.08, 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. The color changes from orange to colorless as the temperature changes. To do.

Preparation of microcapsule particles From 3.0 parts of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane, 3.0 parts of 1,1-bis (4-hydroxyphenyl) decane and 50.0 parts of stearyl caprate The resulting composition is uniformly heated and dissolved, and a solution obtained by mixing 25.0 parts of an aromatic polyisocyanate prepolymer and 50.0 parts of a co-solvent as a wall film material is formed into fine droplets in an 8% aqueous polyvinyl alcohol solution. After emulsifying and dispersing as described above, stirring was continued at 70 ° C. for about 1 hour, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a microcapsule particle suspension.
The suspension was centrifuged to isolate microcapsule particles.
The microcapsule particles had a specific gravity of 0.97 and an average particle diameter of 2.5 μm.

Preparation of reversible thermochromic water-based ink composition 13.0 parts of the reversible thermochromic microcapsule pigment, 7.0 parts of microcapsule particles, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: CELLOSIZE WP-09B] 0.5 part, 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1% diluted phosphoric acid solution 0.1 A reversible thermochromic water-based ink composition was obtained by uniformly stirring and adjusting the pH of the ink to about 5.5.
The specific gravity of the vehicle (ink component excluding reversible thermochromic microcapsule pigment and microcapsule particles) in the ink was 1.03.

Preparation of direct liquid type writing instrument The above-mentioned ink (previously cooled to −20 ° C. or less to cause the microcapsule pigment to develop an orange color and then left at room temperature) and a stirring body (metal sphere having a diameter of 3 mm) The marking pen body [chisel type fiber pen body (porosity of about 53%)] was attached to the tip portion with a valve mechanism interposed therein 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.
The direct liquid writing instrument is provided with a detachable cap, and the cap is provided with a SEBS resin as a scraping member at the top.

An orange character (handwriting) was formed by writing on the paper using the writing instrument.
The handwriting has an orange color at room temperature (25 ° C.), and when characters are scraped with a scraping member attached to a cap, the characters are discolored and become colorless, and this state is maintained at room temperature. Then, by cooling to −20 ° C. or lower, the original orange color was restored, and the discoloration behavior was repeatedly reproduced.

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 2.5 parts, (b) component 4,4 ′-(2-methylpropylidene) bisphenol 3.0 parts, 2,2-bis ( 4'-hydroxyphenyl) hexafluoropropane 5.0 parts, and (c) a reversible thermochromic composition comprising 50.0 parts of 4-benzyloxyphenylethyl caprate as the component is uniformly heated and dissolved to form a wall film material A solution prepared by mixing 25.0 parts of an aromatic polyvalent isocyanate prepolymer and 50.0 parts of a co-solvent is emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution so as to form fine droplets. After stirring for a period of time, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a reversible thermochromic microcapsule pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a specific gravity of 1.08, 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. Turns colorless.

Preparation of microcapsule particles A composition comprising 6.0 parts of 4,4 ′-(2-ethylhexane-1,1-diyl) diphenol and 50.0 parts of butyl stearate is uniformly heated and dissolved to form a wall membrane. A solution prepared by mixing 25.0 parts of an aromatic polyvalent isocyanate prepolymer and 50.0 parts of a co-solvent as materials is emulsified and dispersed in 8% polyvinyl alcohol aqueous solution to form fine droplets, and stirred at 70 ° C. for about 1 hour. After that, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a microcapsule particle suspension.
The suspension was centrifuged to isolate microcapsule particles.
The microcapsule particles had a specific gravity of 0.95 and an average particle size of 2.5 μm.

Preparation of reversible thermochromic aqueous ink composition 14.0 parts of the reversible thermochromic microcapsule pigment, 6.0 parts of microcapsule particles, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: Serosize WP-09B] 0.5 part, 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1% diluted phosphoric acid solution 0.1 A reversible thermochromic water-based ink composition was obtained by uniformly stirring and adjusting the pH of the ink to about 5.5.
The specific gravity of the vehicle (ink component excluding reversible thermochromic microcapsule pigment and microcapsule particles) in the ink was 1.03.

Manufacture of direct liquid writing instrument Axis of the ink (cooled to -20 ° C or less in advance and colored microcapsule pigment in pink and left at room temperature) and stirrer (metal sphere with a diameter of 3 mm) A marking pen body [chisel-type fiber pen body (porosity of about 53%)] was attached to the tip portion through a valve mechanism, and a direct liquid writing instrument (marking pen) was obtained.
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.
The direct liquid writing instrument is provided with a detachable cap, and the cap is provided with a SEBS resin as a scraping member at the top.

The marking pen was used to write on the paper to form pink characters (handwriting).
The handwriting has a pink color at room temperature (25 ° C.). When the character is scraped with a friction body attached to the cap, the character is decolored 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 4
Preparation of reversible thermochromic microcapsule pigment (a) 4.5 parts 2- (2-chloroamino) -6-dibutylaminofluorane as component (4), 4,4 '-(2-methylpropylidene as component (b) ) Reversible thermochromic property comprising 3.0 parts of bisphenol, 5.0 parts of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane, and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c). The composition is uniformly heated and dissolved, and a solution prepared by mixing 25.0 parts of an aromatic polyisocyanate prepolymer and 50.0 parts of a cosolvent as a wall film material is made into fine droplets in an 8% aqueous polyvinyl alcohol solution. The mixture was emulsified and dispersed at 70 ° C. for about 1 hour, and then 2.5 parts of a water-soluble aliphatic modified amine was added. A turbid liquid was obtained.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a specific gravity of 1.09, 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. The color changes from black to colorless as the temperature changes. To do.

Preparation of microcapsule particles From 3.0 parts of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane, 3.0 parts of 1,1-bis (4-hydroxyphenyl) decane, and 50.0 parts of decyl myristate The resulting composition is uniformly heated and dissolved, and a solution obtained by mixing 25.0 parts of an aromatic polyisocyanate prepolymer and 50.0 parts of a co-solvent as a wall film material is formed into fine droplets in an 8% aqueous polyvinyl alcohol solution. After emulsifying and dispersing as described above, stirring was continued at 70 ° C. for about 1 hour, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a microcapsule particle suspension.
The suspension was centrifuged to isolate microcapsule particles.
The microcapsule particles had a specific gravity of 0.97 and an average particle size of 2.5 μm.

Preparation of Reversible Thermochromic Ink Composition 16.0 parts of the reversible thermochromic microcapsule pigment, 9.0 parts of microcapsule particles, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: Serosize WP-09B] 0 0.5 part, 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 57.78 parts of water, 0.1 part of 10% diluted phosphoric acid solution Was added, and the mixture was stirred uniformly to adjust the pH of the ink to about 5.5 to obtain a reversible thermochromic aqueous ink composition.
The specific gravity of the vehicle (ink component excluding reversible thermochromic microcapsule pigment and microcapsule particles) in the ink was 1.03.

Preparation of direct liquid writing instrument The ink (cooled in advance to -20 ° C. or less and colored the microcapsule pigment in black and left at room temperature) and a stirring body (metal sphere having a diameter of 3 mm) A marking pen body [chisel-type fiber pen body (porosity of about 53%)] was attached to the tip portion through a valve mechanism, and a direct liquid writing instrument (marking pen) was obtained.
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.
The direct liquid writing instrument is provided with a detachable cap, and a SEBS resin is attached as a scraping member to the rear end of the shaft tube.

A black character (handwriting) was formed by writing on the paper using the marking pen.
The handwriting has a black color at room temperature (25 ° C.), and when the character is scraped with a friction body attached to the shaft cylinder, the character is discolored and becomes 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 5
Preparation of reversible thermochromic microcapsule pigment (A) 4.0 parts of 4- [2,6-bis (2-ethoxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine as component (B) component A reversible thermochromic composition comprising 10.0 parts of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as the component (c) Dissolve by heating, and emulsify and disperse a solution prepared by mixing 25.0 parts of an aromatic polyvalent isocyanate prepolymer and 50.0 parts of a co-solvent as a wall film material so as to form fine droplets in an aqueous 8% polyvinyl alcohol solution. After stirring at 70 ° C. for about 1 hour, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a reversible thermochromic microcapsule pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a specific gravity of 1.07, 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. The color changes from yellow to colorless according to the temperature change. To do.

Preparation of microcapsule particles From 3.0 parts of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane, 3.0 parts of 1,1-bis (4-hydroxyphenyl) decane and 50.0 parts of stearyl caprate The resulting composition is uniformly heated and dissolved, and a solution obtained by mixing 25.0 parts of an aromatic polyisocyanate prepolymer and 50.0 parts of a co-solvent as a wall film material is formed into fine droplets in an 8% aqueous polyvinyl alcohol solution. After emulsifying and dispersing as described above, stirring was continued at 70 ° C. for about 1 hour, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a microcapsule particle suspension.
The suspension was centrifuged to isolate microcapsule particles.
The microcapsule particles had a specific gravity of 0.97 and an average particle size of 2.5 μm.

Preparation of reversible thermochromic water-based ink composition 13.0 parts of the reversible thermochromic microcapsule pigment, 7.0 parts of microcapsule particles, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: CELLOSIZE WP-09B] 0.5 part, 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1% diluted phosphoric acid solution 0.1 The reversible thermochromic water-based ink composition was prepared by uniformly stirring and adjusting the pH of the ink to about 5.5.
The specific gravity of the vehicle (ink component excluding reversible thermochromic microcapsule pigment and microcapsule particles) in the ink was 1.03.

Preparation of a writing instrument The ink (previously cooled to −20 ° C. or less to cause the microcapsule pigment to develop a yellow color and then allowed to stand at room temperature) and a stirrer (a metal sphere having a diameter of 3 mm) are placed in a shaft cylinder. A marking pen body [chisel type fiber pen body (porosity of about 53%)] was attached to the tip portion through a built-in valve mechanism 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.
The direct liquid writing instrument is provided with a detachable cap, and a SEBS resin is attached as a scraping member to the rear end of the shaft tube.

A yellow character (handwriting) was formed by writing on the paper using the marking pen.
The handwriting has a yellow color at room temperature (25 ° C.), and when the character is scraped with a friction body attached to the shaft cylinder, the character is decolored 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 6
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) -isobonzofuran] -3-one 2.5 parts, (b) 1,1-bis (4-hydroxyphenyl) decane 4.0 parts, 2,2-bis ( 4'-hydroxyphenyl) hexafluoropropane 4.0 parts, (c) as a component, 10.0 parts of cetyl caprate and 40.0 parts of stearyl caprate as a reversible thermochromic composition are uniformly heated and dissolved. A solution prepared by mixing 25.0 parts of aromatic polyisocyanate prepolymer and 50.0 parts of a co-solvent as a wall film material is emulsified and dispersed in 8% polyvinyl alcohol aqueous solution to form fine droplets. After stirring for a period of time, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a reversible thermochromic microcapsule pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a specific gravity of 0.98, an average particle size of 2.4 μm, a complete color erasing temperature of 33 ° C., and a complete color development temperature of 24 ° C. The color changes from pink to colorless according to the temperature change. To do.

Preparation of microcapsule particles 4,4 ′-(2-ethylhexane-1,1-diyl) diphenol 6.0 parts and capric acid 4-benzyloxyphenylethyl 50.0 parts capric acid uniformly heated Dissolve and emulsify and disperse a solution prepared by mixing 25.0 parts of an aromatic polyvalent isocyanate prepolymer and 50.0 parts of a co-solvent as a wall film material into fine droplets in an 8% aqueous polyvinyl alcohol solution, After stirring for about 1 hour, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a microcapsule particle suspension.
The suspension was centrifuged to isolate microcapsule particles.
The microcapsule particles had a specific gravity of 1.07 and an average particle size of 2.3 μm.

Preparation of reversible thermochromic water-based ink composition 12.0 parts of the above reversible thermochromic microcapsule pigment, 8.0 parts of microcapsule particles, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: Serosize WP-09B] 0.5 part, 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1% diluted phosphoric acid solution 0.1 A reversible thermochromic water-based ink composition was obtained by uniformly stirring and adjusting the pH of the ink to about 5.5.
The specific gravity of the vehicle (ink component excluding reversible thermochromic microcapsule pigment and microcapsule particles) in the ink was 1.03.

Preparation of direct liquid writing instrument The ink (cooled in advance to 24 ° C. or less to cause the microcapsule pigment to develop a pink color and then allowed to stand at room temperature) and a stirring body (a metal sphere having a diameter of 3 mm) A marking pen body [cannonball type fiber pen body (porosity of about 50%)] was attached to the tip portion through a valve mechanism, and a direct liquid writing instrument (marking pen) was obtained.
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.
The direct liquid writing instrument is provided with a detachable cap.

The marking pen was used to write on the paper to form pink characters (handwriting).
The handwriting has a pink color at room temperature (25 ° C.), and when it is rubbed with a finger, the character is decolored and colorless. This state is maintained at room temperature and is cooled to 24 ° C. or lower. Thus, the original pink color was restored, and the discoloration behavior was reproduced repeatedly.

Comparative Example 1
Preparation of reversible thermochromic water-based ink composition 20.0 parts of reversible thermochromic microcapsule pigment of Example 1, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: cellosize WP-09B], Add 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1 part of 10% diluted phosphoric acid solution, The mixture was stirred uniformly to prepare a reversible thermochromic water-based ink composition.

Production of direct liquid writing instrument The ink was incorporated in the same writing instrument as in Example 1 to obtain a direct liquid writing instrument.

Comparative Example 2
Preparation of reversible thermochromic aqueous ink composition 20.0 parts of reversible thermochromic microcapsule pigment of Example 2, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: cellosize WP-09B], Add 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1 part of 10% diluted phosphoric acid solution, A reversible thermochromic aqueous ink composition was prepared by stirring uniformly and adjusting the pH of the ink to about 5.5.

Production of direct liquid writing instrument The ink was incorporated in the same writing instrument as in Example 2 to obtain a direct liquid writing instrument.

Comparative Example 3
Preparation of reversible thermochromic aqueous ink composition 20.0 parts of reversible thermochromic microcapsule pigment of Example 3, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: cellosize WP-09B], Add 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1 part of 10% diluted phosphoric acid solution, A reversible thermochromic aqueous ink composition was prepared by stirring uniformly and adjusting the pH of the ink to about 5.5.

Production of direct liquid writing instrument The ink was incorporated in the same writing instrument as in Example 3 to obtain a direct liquid writing instrument.

Comparative Example 4
Preparation of reversible thermochromic water-based ink composition 25.0 parts of reversible thermochromic microcapsule pigment of Example 4, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: cellosize WP-09B], Add 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 57.28 parts of water, 0.1 part of 10% diluted phosphoric acid solution, A reversible thermochromic aqueous ink composition was prepared by stirring uniformly and adjusting the pH of the ink to about 5.5.

Production of direct liquid writing instrument The ink was incorporated in the same writing instrument as in Example 4 to obtain a direct liquid writing instrument.

Comparative Example 5
Preparation of reversible thermochromic water-based ink composition 20.0 parts of reversible thermochromic microcapsule pigment of Example 5, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: cellosize WP-09B], Add 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1 part of 10% diluted phosphoric acid solution, The ink was uniformly stirred and the pH of the ink was adjusted to about 5.5 to obtain a reversible thermochromic aqueous ink composition.

Production of direct liquid writing instrument The ink was incorporated in the same writing instrument as in Example 5 to obtain a direct liquid writing instrument.

Comparative Example 6
Preparation of reversible thermochromic aqueous ink composition 20.0 parts of reversible thermochromic microcapsule pigment of Example 6, hydroxyethyl cellulose [manufactured by Union Carbide Japan Co., Ltd., trade name: cellosize WP-09B], Add 15.0 parts of glycerin, 0.02 part of antifoaming agent, 1.5 parts of preservative, 0.2 part of surface tension adjusting agent, 62.78 parts of water, 0.1 part of 10% diluted phosphoric acid solution, A reversible thermochromic ink was obtained by stirring uniformly and adjusting the pH of the ink to about 5.5.

Production of direct liquid writing instrument The ink was incorporated in the same writing instrument as in Example 6 to obtain a direct liquid writing instrument.

The following tests were conducted using the direct liquid writing instruments obtained in the above Examples and Comparative Examples.
Aging test The writing tools produced in Examples 1 to 6 and Comparative Examples 1 to 6 were placed in a 50 ° C. thermostatic bath in an upright state (writing tip portion upward) and an inverted state (writing tip portion downward), and left for 30 days. After taking out from a thermostat and cooling to 0 degreeC, the state of the ink was observed visually. Next, after each writing instrument was shaken in the vertical direction for 10 seconds, 10 lines were written on the report paper, and the state of the handwriting was visually observed.

The test results are shown in the following table.

In addition, the evaluation regarding the symbol in a table | surface is as follows.
Ink state ○: The microcapsule pigment is uniformly dispersed in the ink.
X: The microcapsule pigment is separated in the ink.
State of handwriting ○: The handwriting has the same color density as the initial stage.
Δ: The handwriting is lighter than the initial one.
X: A handwriting cannot be formed.

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.

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 coloring type T ₄ Color development temperature of the reversible thermochromic microcapsule pigment of the ₄ heating coloring type

Claims (10)

An ink composition incorporated in a direct liquid writing instrument containing an agitator that stirs ink in a shaft cylinder, the ink composition comprising: (b) an electron-donating color-forming organic compound, and (b) electron accepting. (C) a reversible thermochromic microcapsule pigment encapsulating a reversible thermochromic composition comprising a reaction medium that determines the occurrence temperature of the color reaction of both, and the reversible thermochromic microcapsule pigment (B) an electron-accepting compound comprising a microcapsule particle having a different specific gravity, a vehicle containing water and a polymer flocculant, and a component encapsulated in the microcapsule particle is encapsulated in a reversible thermochromic microcapsule pigment; (c) a reaction medium determining the occurrence temperature of color reaction of the both, the ratio of the vehicle between the specific gravity and the microcapsule particles during color development of the reversible thermal discoloration microcapsule pigment Reversible thermal discoloration aqueous ink composition but present. An ink composition incorporated in a direct liquid writing instrument containing an agitator that stirs ink in a shaft cylinder, the ink composition comprising: (b) an electron-donating color-forming organic compound, and (b) electron accepting. (C) a reversible thermochromic microcapsule pigment encapsulating a reversible thermochromic composition comprising a reaction medium that determines the occurrence temperature of the color reaction of both, and the reversible thermochromic microcapsule pigment (B) an electron-accepting compound comprising a microcapsule particle having a different specific gravity, a vehicle containing water and a polymer flocculant, and a component encapsulated in the microcapsule particle is encapsulated in a reversible thermochromic microcapsule pigment; (c) a reaction medium determining the occurrence temperature of color reaction of the both reversible thermal discoloration microcapsule pigment density at color development (X), the microcapsule particle density (Y), bi arsenide Le specific gravity (Z) has the formula (1) and a reversible thermal discoloration aqueous ink composition satisfying (2).
Z + 0.02 ≦ X ≦ Z + 0.2 (1)
Z−0.25 ≦ Y ≦ Z−0.03 (2) An ink composition incorporated in a direct liquid writing instrument containing a stirring body for stirring ink, wherein the ink composition comprises (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, C) A reversible thermochromic microcapsule pigment encapsulating a reversible thermochromic composition comprising a reaction medium that determines the temperature at which the color reaction of the two occurs, and the reversible thermochromic microcapsule pigment having different specific gravity (B) an electron-accepting compound, and (c) the above-mentioned components encapsulated in a reversibly thermochromic microcapsule pigment comprising capsule particles and a vehicle containing water and a polymer flocculant. a reaction medium which determines the occurrence temperature of both the color reaction, the reversible thermal discoloration microcapsule pigment density at color development (X), the ratio of the specific gravity (Y), vehicle of the microcapsule particles (Z) has the formula (3) and (4) Reversible thermochromic ink composition for a writing instrument satisfying.
Z−0.25 ≦ X ≦ Z−0.03 (3)
Z + 0.02 ≦ Y ≦ Z + 0.2 (4) The reversible thermochromic water-based ink composition according to any one of claims 1 to 3, wherein the vehicle contains a water-soluble organic solvent, and the specific gravity of the water-soluble organic solvent is 1.1 or more. The reversible thermochromic water-based ink composition according to any one of claims 1 to 3, wherein the viscosity of the ink is in the range of 2 to 20 mPa · s. A direct liquid writing instrument comprising the reversible thermochromic water-based ink composition according to any one of claims 1 to 5 together with a stirring member. The direct liquid writing instrument according to claim 6, wherein a valve mechanism is provided in the shaft cylinder. 8. The direct liquid writing instrument according to claim 7, wherein the valve mechanism is a mechanism that opens the valve by pressing a pen body provided at a writing tip. The direct liquid writing instrument according to claim 8, wherein the valve opens by a pressure applied to the pen body at the time of writing. The direct liquid writing instrument according to claim 8 or 9, wherein the pen body is a marking pen body.

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