JP2005088308A - Writing utensil equipped with thermally discolored reversible appearing and disappearing function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a writing utensil effective for learning, taking notes or the like, in which the vision of a printed image or a written image under normal temperature range can be prevented from developing by forming a reversible thermally discolored hiding handwriting layer for covering the printed image or the written image and which is equipped with a thermally discolored reversible appearing and disappearing function, which bares the image under a visible state by discoloring the handwriting image with the frictional heat developed by scratching the handwriting image with a rubbing body. <P>SOLUTION: The writing utensil with the thermally discolored reversible appearing and disappearing function can form the handwriting with a lightness value of color density of not more tahn 4.5 in color development and a lightness value of not less than 5 in discolored state by the frictional heat by using an ink prepared by dispersing 10-45 wt.% of the specified reversible thermally discolored micro-capsulated pigment having a high temperature side perfectly discoloring temperature in the range of 30-80°C in a water-based medium, and has the rubbing body for the handwriting. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a writing instrument having a thermochromic reversible concealment function. Specifically, a reversible thermochromic concealing handwriting layer that covers a printed image or a written image can be formed to obstruct vision of the image in a normal temperature range, and the handwriting layer is discolored by frictional heat due to friction of a friction body. It is related with the writing instrument provided with the thermochromic reversible concealment function which makes the said image appear in a visible state by doing.

Conventionally, fluorescent markers that can be used for memorization, learning, and the like by modifying appropriate portions such as texts, phrases, and numbers in textbooks, English word dictionaries, etc., with fluorescent handwriting are added.
Several proposals have been disclosed regarding writing instruments that form thermochromic handwriting and impart distinctiveness.
JP 2001-207104 A JP 2003-206432 A

Even if the modification system by the fluorescent handwriting by the fluorescent marker can give distinctiveness, the sentence, the phrase, etc. are visible, and the memorization and learning effects are not always satisfied.
Further, even if the thermochromic concealment layer is formed by a conventional writing instrument for forming a thermochromic handwriting, the concealing effect of the lower layer printed image is not satisfied.
The present invention can form a concealing layer that covers a printed image or a written image by handwriting to prevent vision of the image in a normal temperature range, and discolor the concealing layer formed by the handwriting by frictional heat by rubbing a friction body. The present invention is intended to provide a convenient writing instrument having a thermochromic reversible concealing function that makes the image appear in the original visible state by satisfying the above, and satisfying discriminability and memorization learning effect.

The present invention can form a reversible thermochromic concealing handwriting layer that covers a printed image or a written image, thereby preventing the image from being visually perceived in a normal temperature range, and discoloring the handwriting layer by frictional heat due to friction of a friction body. A writing instrument having a thermochromic reversible concealment function that reveals the image in a visible state by having a high-temperature side complete discoloration temperature that minimizes the color density in a range of 25 to 60 ° C. A reversible thermochromic ink in which 10 to 45% by weight of a reversible thermochromic microcapsule pigment having an average particle diameter in the range of 1 to 6 μm is dispersed in an aqueous medium is allowed to flow out from the writing tip to produce a color density in a colored state. A lightness value of at least 4.5 or less, and a reversible thermochromic concealing handwriting layer having a lightness value in a discolored state due to frictional heat of at least 5.0 or more can be formed, and the friction imparting frictional heat due to the abrasion The be a requirement writing tool having a thermochromic reversible Inken function characterized by comprising.
Furthermore, a non-thermochromic colorant is blended in the ink or in the reversible thermochromic microcapsule pigment, and the agglomeration system in which the reversible thermochromic microcapsule pigment is suspended in a gentle agglomerated state. It is a requirement that ink is filled in an ink occlusion body made of a fiber converging body accommodated in a shaft cylinder and configured to be able to flow out from a fiber pen body made of a fiber processed body.
Furthermore, it is a structure provided with a writing body that forms a handwriting by a non-thermochromic ink at the other end, and a structure in which the handwriting by the non-thermochromic ink can be concealed by a reversible thermochromic concealing handwriting layer. The requirement is that the handwriting by the non-thermochromic ink and the reversible thermochromic concealing layer at the time of color development have the same or similar hue.

The present invention can form a reversible thermochromic concealing layer that effectively prevents vision in a normal temperature range of a printed image or a written image at any location by handwriting by writing, and when necessary, the concealing layer is formed by rubbing a friction body. It can be discolored by frictional heat and restored to its original visual state, and it is practical as a writing instrument with a convenient thermochromic reversible concealment function that satisfies discriminability and memorization learning effects.
Furthermore, in the form of a double-headed writing instrument, one is used for writing with a non-thermochromic ink and the other is used for forming a reversible thermochromic concealing handwriting that conceals the written image. Concealment can be obtained, and convenience can be further improved.

The brightness value in the above will be described.
The lightness value indicates the lightness value of the Munsell color chart system, in which a perfect black is 0 and a complete white is 10 in an achromatic array, so that the brightness difference between them is equal. The lightness of the chromatic color indicates the lightness value of the achromatic color in which the sensation of the brightness of the chromatic color is equal. That is, the smaller the brightness value, the closer to black and the higher the visual density, and the higher the brightness value, the closer to white and the smaller the visual density. In addition, the lightness value is obtained by using a TC-3600 color difference meter manufactured by Tokyo Denshoku Co., Ltd., after forming handwriting on a white support (quality paper), and in each of a completely colored state and a completely discolored state (including decoloring). The value obtained by measuring the brightness value is shown.

Usually, a printed image or a written image is mostly in a black or dark blue hue, and the lightness value shows a correspondingly small value. Therefore, in order to hinder the visual perception of the image, a concealment layer is required that exhibits a lightness value close to or less than the image.
In the system in which the concealing layer is formed by printing with a thermochromic printing ink, the coloring ratio of the thermochromic pigment per unit area is increased by increasing the blending ratio of the thermochromic pigment and increasing the viscosity. The color density can be increased, and the thickness of the printing layer can be set relatively large so that the concealing function can be exhibited.
The present invention allows the user itself to form a reversible thermochromic concealment layer by handwriting at an arbitrary place, and discolors the concealment layer by rubbing heat by a friction body to reveal a concealed image as a writing instrument. It must have requirements such as ink outflow suitability and storage stability over time.
Therefore, the thermochromic microcapsule pigment is stably held in a dispersed state in the ink in a low-viscosity system, and a suitable amount flows out from the capillary gap at the tip of the writing, making it clear and concealed. The handwriting having the sexual function can be formed, and furthermore, the handwriting must have durability against repeated abrasion by the friction body.
In order to satisfy the above-mentioned writing suitability, the scratching strength of the handwriting and the like, and to effectively develop reversible concealment, the reversible thermochromic concealing handwriting has a lightness value of color density of at least 4.5 in a colored state. The lightness value in the discolored state due to frictional heat is at least 5.0 or more.
Here, a non-thermochromic colorant, for example, a chromatic dye, for example, orange, pink, green, blue, or the like is appropriately added in the ink or the microcapsule pigment within the range satisfying the above-described brightness value. The composition is changed to colored (2) by frictional heat from the colored state [colored (1)], and the lightness of color density at the time of coloring in a system that changes from colored (1) to colorless. The value can be increased and a concealing reinforcing function can be achieved.

The reversible thermochromic microcapsule pigment is a conventionally known (a) electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction that determines the temperature at which the color reaction of both occurs. The reversible thermochromic composition containing the three essential components of the medium is effective when encapsulated in a microcapsule, and the present applicant has proposed as a heat decoloring type for decoloring by heating from a colored state. JP-B-51-44706, JP-B-51-44707, JP-B-1-29398 and the like can be used. The color changes before and after a predetermined temperature (discoloration point), exhibits a decolored state in a temperature range above the high temperature side discoloration point, and develops a color development state in a temperature range below the low temperature side discoloration point. There is only one specific state 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 not applied, the state returns to the state exhibited in the normal temperature range. _A material having a relatively small width (ΔH _A = 1 to 7 ° C.) can be applied (see FIG. 4).
In the - APPLICATION silicic fatty acid esters indicating the (cloud point melting point) as a color change temperature regulator compounds shown in KOKOKU 1-29398 JP, 3 ° C. below ΔT value], [Delta] H _A is 3 ° C. following system the boundary of the high temperature side color change point and the low temperature side color change point and sensitively responds to temperature changes show the discoloration of sensitive, after color change in [Delta] H _a is 4 to 7 ° C. about the system, slowly return to the original aspect, The visual effect can be enhanced.
In addition, the large hysteresis characteristics (ΔH described in Japanese Patent Publication No. 4-17154, Japanese Patent Application Laid-Open No. 7-179777, Japanese Patent Application Laid-Open No. 7-33997, Japanese Patent Application Laid-Open No. 8-39936, etc. proposed by the present applicant. _B = 8-50 ° C.), that is, the shape of the curve plotting the change in color density due to the temperature change is higher than the color change temperature range, contrary to the case where the temperature is raised from the lower temperature side than the color change temperature range. The color changes by following a path that differs greatly from the case of lowering from the low temperature side, the color development state in the low temperature range below the low temperature side discoloration point (t ₁ ), or the color disappearance in the high temperature range above the high temperature side discoloration point (t ₄ ). A color state in which a temperature-sensitive color-changing color memory composition that can be stored in a specific temperature range [temperature range between t _{2 and} t ₃ (substantially two-phase holding temperature range)] is encapsulated in a microcapsule Applicable (see FIG. 5).

The microcapsule pigment applied to the present invention does not refuse application in the form of a circular cross section, but is effective in the form of a non-circular cross section (see FIG. 6).
The reversible thermochromic concealment layer formed by writing has the above-mentioned microcapsule pigment densely oriented and fixed with the long diameter side (maximum outer diameter side) in close contact with the surface to be written. The microcapsule pigment is slightly elastically deformed into a shape that relaxes the external force against an external force caused by friction with a friction body such as an eraser, an elastomer molded body, or a plastic molded body. Can be effectively expressed without impairing the thermochromic function. Here, the microcapsule pigment having a non-circular cross-sectional shape has an average value of the maximum outer diameter in the range of 1 to 5 μm, and the reversible thermochromic composition / wall film = 7/1 to 1/1 (weight ratio). Must meet the scope of

The microcapsule pigments (including those having a circular cross-sectional shape) exhibit a decrease in the ability to flow out from the capillary gap in a system having an average value of the maximum outer diameter exceeding 6.0 μm, whereas the average of the maximum outer diameter In systems where the value is less than 1 μm, it is difficult to show high-density color developability. Preferably, the average value of the maximum outer diameter is in the range of 1 to 4 μm, the average particle diameter of the microcapsules [(maximum outer diameter + central portion The minimum outer diameter) / 2] is preferably in the range of 1 to 3 μm.
If the ratio of the reversible thermochromic composition to the wall film is larger than the above range, the wall film becomes too thin, causing a decrease in pressure and heat resistance, and conversely, the reversible thermochromic composition of the wall film. When the ratio to the above is larger than the above range, the color density and sharpness during color development are unavoidable, and preferably the reversible thermochromic composition / wall film = 6/1 to 1/1 (weight ratio). .

  The reversible thermochromic microcapsule pigment can be blended in an amount of 10 to 45% by weight (preferably 20 to 40% by weight) based on the total amount of the ink composition. If it is less than 10% by weight, the visual density is insufficient and it is difficult to satisfy the desired brightness value. On the other hand, when it exceeds 45% by weight, it is difficult for the ink to stably flow out from the writing tip, and the writing property is hindered.

  In addition, for the microencapsulation of the reversible thermochromic composition, known means such as an interfacial polymerization method, an interfacial polycondensation method, an in situ polymerization method, a coacervate method, etc. can be applied, but the particles satisfying the above-mentioned requirements of the present invention In order to obtain a microcapsule pigment having a non-circular cross-sectional shape in the diameter range, an interfacial polymerization method or an interfacial polycondensation method that hardly causes aggregation and coalescence can be applied.

  The reversible thermochromic concealing ink in the present invention is a coagulation ink in which a reversible thermochromic microcapsule pigment is suspended in a gentle coagulation state with a water-soluble polymer coagulant, and a shear thinning system containing a shear thinning substance. Ink, a specific gravity control type ink in which the reversible thermochromic microcapsule pigment is adjusted to have a specific gravity difference of 0.05 or less from the aqueous vehicle are effective.

  As the agglomerated ink, Japanese Patent Application Laid-Open No. 2001-207101 proposed by the applicant is applied, and a reversible thermochromic microcapsule pigment of 10 to 45% by weight, a binder resin containing a water-soluble polymer flocculant 0.05 to 25% by weight, the balance is made up of water containing a humectant if necessary, and adjusted to a viscosity range of 3 to 20 mPa · s (25 ° C.) to obtain an agglomerated reversible thermochromic hiding ink.

  As the shear-thinning ink, Japanese Patent Application Laid-Open No. 9-124993 already proposed by the present applicant is applied, 10 to 45% by weight of reversible thermochromic microcapsule pigment, and shear-thinning resin 0.1 to 0.5. Part by weight, containing 5 to 35% by weight of a water-soluble organic solvent, the balance being water, the viscosity is 40 to 300 mPa · s (value at a rotation speed of 10 rpm by an EM type rotational viscometer), the shear thinning index 0.1 A ballpoint pen ink is prepared by adjusting to a range of ˜0.8 to obtain a shear thinning system reversible thermochromic hiding ink.

  The specific gravity control type ink is prepared by applying Japanese Patent No. 2540341 (Japanese Patent Application No. 62-210721) proposed by the present applicant, and filled in the shaft cylinder of a general-purpose writing instrument equipped with a pumping mechanism. Can be applied.

As the aqueous polymer flocculant, a nonionic water-soluble polymer compound is preferably used.
Specific examples include polyvinyl pyrrolidone, polyethylene oxide, water-soluble polysaccharides, nonionic water-soluble cellulose derivatives, and the like. Among these, specific examples of water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, and specific examples of nonionic water-soluble cellulose derivatives include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, Examples thereof include hydroxypropylmethylcellulose. Any water-soluble polymer exhibiting a loose bridging action between the microcapsule pigment particles in the reversible thermochromic water-based ink composition of the present invention can be applied, and in particular, the nonionic water-soluble cellulose described above. The derivatives most effectively act on the reversible thermochromic aqueous ink composition of the present invention.
The polymer flocculant can be blended in an amount of 0.05 to 20% by weight based on the total amount of the ink composition.

As moisturizing agents to suppress drying at the nib, glycols such as glycerin, propylene glycol, ethylene glycol, diethylene glycol, and low molecular weight polyethylene glycol and their lower alkyl ethers, 2-pyrrolidone, N-vinylpyrrolidone, urea, etc. The appropriate amount can be blended.
The humectant can be blended in an amount of 5 to 40% by weight based on the total amount of ink.

An appropriate amount of binder resin can also be added for adjusting the stickiness of the handwriting and adjusting the viscosity. The binder resin is selected from a resin emulsion, an alkali-soluble resin, and a water-soluble resin.
Examples of the resin emulsion include polyacrylic acid ester, styrene-acrylic acid copolymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, ethylene-vinyl chloride copolymer, methacrylic acid-maleic acid copolymer, ethylene- Examples include aqueous dispersions such as methacrylic acid copolymers, α-olefin-maleic acid copolymers, polyesters, and polyurethanes. Examples of the alkali-soluble resins include styrene-maleic acid copolymers and ethylene-maleic acid copolymers. Styrene-acrylic acid copolymer, and the like. Examples of the water-soluble resin include polyvinyl alcohol, polyvinyl butyral, and the like, and one or a mixture of two or more can be used.
Moreover, conventionally various various dispersing agents, such as surfactant, can be mix | blended as needed.

  The shear thinning substance is a nonionic surfactant having an HLB value in the range of 8 to 12, xanthan gum, welan gum, succinoglycan whose constituent monosaccharide is an organic acid-modified heteropolysaccharide of glucose and galactose (average molecular weight) About 1,000 to 8 million), guar gum, locust bean gum and derivatives thereof, hydroxycellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 based on alkyl esters of methacrylic acid, glucomannan, agar and carrageenan Examples include carbohydrates having gelling ability extracted from seaweed such as benzylidene sorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid polymers, and the like, which can be used alone or in combination. Xanthan gum, succinoglycan, and crosslinkable acrylic acid polymer are particularly excellent in storage stability.

In the application of the agglomerated ink, a large number of fibers are placed in close contact with each other, a fiber processed body in which capillary gaps are formed between adjacent fibers is used as a pen body, and capillary gaps are formed between adjacent fibers. The fiber converging body is used as an ink occlusion body, the rear end of the pen body is assembled to the front end of the ink occlusion body, and the ink occlusion body is impregnated with the agglomerated ink to form a writing instrument.
The fiber processed body is a porous member having a continuous ventilation hole selected from the range of generally 40 to 70% of porosity, such as a resin processed body of a fiber, a fusion processed body of a heat-meltable fiber, and a felt body. Yes, one end of the fiber processed body is processed into a shape corresponding to the purpose such as a bullet shape, a rectangular shape, a chisel shape or the like to form a pen body and put to practical use.
The chisel-shaped pen body has versatility that can form marks with a constant line width for fine writing or for thick writing by changing the contact position on the writing surface. A reversible thermochromic masking layer can be formed by forming a simple handwriting.
The fiber bundle ink occlusion body is formed by converging crimped fibers in the longitudinal direction. The fiber bundle ink occlusion body is contained in a covering body such as a plastic cylinder or a film, and the porosity is adjusted to a range of approximately 50 to 93%. Composed. The fiber bundle ink occlusion body may be a fiber bundle resin-processed or heat-sealed, or welded by a plasticizer or the like.

  The above-mentioned shear-thinning ink can be configured as a ballpoint pen-shaped writing instrument by filling a shaft barrel provided with a tip that rotatably holds a ball at the tip, and a liquid stopper (follower) at the rear. .

As a writing instrument in the present invention, a double-ended type comprising a writing tip at both ends of a shaft cylinder, a reversible thermochromic concealing ink filled in one half of the shaft cylinder, and a non-thermochromic ink filled in the other half The marker form also satisfies practical convenience.
Here, the handwriting by the non-thermochromic ink is a concealable combination in which the lightness value of the reversible thermochromic concealing handwriting layer is at least 4.5 or less, the handwriting by the non-thermochromic ink, and the coloring The reversible thermochromic concealing hiding layer is a combination having the same or similar hue, so that convenience for the user can be improved.

  The friction body that changes the color of the reversible thermochromic concealing layer by frictional heat has a configuration in which a rear end portion of a shaft barrel of a writing instrument, a constituent member such as a tail plug, a cap tip, and an elastomer are mounted on the cap or the rear portion of the shaft barrel. It is valid.

The parts in the following examples represent parts by weight.
Example 1
Preparation of reversible thermochromic hiding ink 2- (2-chloroanilino) -6-di-n-butylaminofluorane 5.0 parts, 1,1-bis- (4-hydroxyphenyl) hexafluoropropane 4.0 A reversible thermochromic composition consisting of 10.0 parts of 1,1-bis (4′hydroxyphenyl) n-decane and 50.0 parts of p-methylbenzyl palmitate is dissolved by heating to give a fragrance as a wall membrane material 30 parts of an isocyanate isocyanate prepolymer / ethyl acetate solution (prepolymer concentration: 75% by weight) was added to a 100% part of a 6% by weight polyvinyl alcohol aqueous solution heated to 70 ° C. while stirring, and the mixture was stirred. After emulsifying into fine droplets, the mixture was further reacted at 80 ° C. for 5 hours to obtain a stock solution of a microcapsule pigment containing a reversible thermochromic composition. Subsequently, reversible thermochromic microcapsule pigments (average particle size: 3.0 μm; t ₁ : 3 ° C., t ₂ : 8 ° C., t ₃ : 35 ° C., t ₄ : 42 ° C.) are obtained by centrifuging the stock solution. Obtained.
35 parts of the reversible thermochromic microcapsule pigment, 15 parts of glycerin, 0.5 part of an antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation), silicone antifoaming agent (trade name: SN deformer 381) , Sannopco Co., Ltd.) 0.1 part, hydroxyethyl cellulose as a flocculant (trade name: Cellosize WP-09L, Union Carbide Japan Co., Ltd.) 0.4 part, general blue dye (trade name: Water Blue 117L, 1.0 part of Orient Chemical Industry Co., Ltd. and 48.0 parts of water were uniformly stirred to obtain a reversible thermochromic concealing ink.
Preparation of writing instrument In a fiber bundle ink occlusion body (porosity 90.9%) covered with a polyester resin sliver and impregnated immediately after stirring the reversible thermochromic concealing ink in a uniform state. Connected to a fiber pen body (having a porosity of about 60%) with a tip end processed into a chisel shape for a handwriting width of 4 mm) The writing instrument provided with the thermochromic reversible concealment function was prepared by assembling in a state and fitting a tail plug to the rear part of the shaft barrel. Here, the rear end of the tail plug is formed in a curved surface and has a frictional body function.
Handwriting performance A reversible thermochromic concealing handwriting layer was formed by writing a handwriting of 10 cm length (handwriting width: 4 mm) at a writing speed of 2 seconds on a report paper with the writing tool.
The handwriting layer exhibits a black color at room temperature (25 ° C.), changes to blue when heated to 42 ° C., and the blue state is maintained at room temperature. It was restored and the discoloration behavior was repeated and reproduced.
The lightness value of the black state of the handwriting layer was 3.50, and the lightness value of the blue state was 5.50. A black reversible thermochromic concealment layer was formed by concealing the black character print image with the writing instrument at room temperature at the same writing speed as described above. It showed possible concealment. Next, when the handwriting layer was rubbed with the curved surface portion at the rear end of the tail plug, the color changed to blue, and the character printed image was changed to a legible state, and this state was kept at room temperature. Subsequently, when the temperature was cooled to 3 ° C. or lower, the blue handwriting layer was restored to the original black color, and the character print image was kept in an unreadable state again.

Example 2
Preparation of reversible thermochromic hiding ink 6 '-[Ethyl (4-methylphenyl) amino] -2'-(methylphenylamino) -spiro [isobenzofuran-1 (3H), 9 '-(9H) xanthene] 7.0 parts of -3-one, 4.0 parts of 1,1-bis- (4-hydroxyphenyl) hexafluoropropane, 10.0 parts of 1,1-bis (4′hydroxyphenyl) n-decane, stearic acid A reversible thermochromic composition composed of 50.0 parts of neopentyl was heated and dissolved, and 30 parts of an aromatic isocyanate prepolymer / ethyl acetate solution (prepolymer concentration: 75% by weight) was added as a wall film material and dissolved uniformly. The solution was poured into 100 parts of a 6% by weight polyvinyl alcohol aqueous solution heated to 70 ° C. with stirring, emulsified into fine droplets, and further reacted at 80 ° C. for 5 hours. To give a stock solution of the reversible thermal discoloration microcapsule pigment including reverse thermochromic composition. Next, by reversing the stock solution, reversible thermochromic microcapsule pigments (average particle size 2.0 μm: t ₁ : 8 ° C., t ₂ : 11 ° C., t ₃ : 29 ° C., t ₄ : 35 ° C.) Obtained.
Using 35 parts of the reversibly thermochromic microcapsule pigment, 0.4 part of a general color blue dye (trade name: Water Blue 117L, manufactured by Orient Chemical Co., Ltd.), a general red dye (trade name: Edible Red No. 3 Daiwa A reversible thermochromic concealing ink was obtained in the same manner as in Example 1 except that 0.20 part (made by Kasei Co., Ltd.) was blended.
Fabrication of writing instrument Thermal discoloration using the same fiber bundle ink occlusion body and fiber pen body as in Example 1, except that a cap equipped with an abrasion molded body having a curved tip formed of an elastomer molded body is used at the tip of the cap. A writing instrument with a reversible concealment function was prepared.
Handwriting performance A reversible thermochromic concealing handwriting layer was formed by writing a handwriting of 10 cm length (handwriting width: 4 mm) at a writing speed of 2 seconds on a report paper with the writing tool.
The handwriting layer exhibits a black color at room temperature (25 ° C.), changes to purple when heated to 35 ° C., and the purple state is maintained at room temperature. It was restored and the discoloration behavior was repeated and reproduced.
The lightness value of the handwriting layer was 3.04 in the black state and 5.08 in the purple state.
A black reversible thermochromic concealment layer was formed by concealing the black character print image with the writing instrument at room temperature at the same writing speed as described above. It showed possible concealment. Next, when the handwriting layer was rubbed with a friction body at the tip of the cap, the color changed to purple, and the printed character image was changed to a legible state, and this state was kept at room temperature. Next, when the temperature was cooled to 8 ° C. or lower, the blue handwriting layer was restored to the original black color, and the character print image was kept in an unreadable state again.

Example 3
Preparation of reversible thermochromic hiding ink 6 '-(dipentylamino) -2'-[(3- (trifluoromethyl) phenyl) amino] -spiro [isobenzofuran-1 (3H), 9 '-(9H ) Xanthene] -3-one 7.0 parts, 1,1-bis- (4-hydroxyphenyl) hexafluoropropane 6.0 parts 1,1-bis (4′hydroxyphenyl) n-decane 10.0 parts, A reversible thermochromic composition comprising 25.0 parts of stearyl laurate, 25.0 parts of stearyl caprate and 1.0 part of distearyl ketone is dissolved by heating, and an aromatic isocyanate prepolymer / ethyl acetate solution is used as a wall film material. (Prepolymer concentration: 75% by weight) 30 parts are added, and the uniformly dissolved solution is added to 100 parts of a 6% by weight polyvinyl alcohol aqueous solution heated to 70 ° C. with stirring. It was emulsified into droplets, further, by 5 hours of reaction at 80 ° C., to obtain a stock solution of the reversible thermal discoloration microcapsule pigment including a reversible thermochromic composition. Subsequently, a reversible thermochromic microcapsule pigment (average particle size: 2.0 μm: t ₁ : 25 ° C., t ₂ : 30 ° C., t ₃ : 33 ° C., t ₄ : 40 ° C.) is obtained by centrifuging the stock solution. Obtained.
35 parts of the reversible thermochromic microcapsule pigment, 15 parts of glycerin, 0.5 part of an antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Co., Ltd.), silicone antifoaming agent (trade name: SN deformer 381) , Sannopco Co., Ltd.) 0.1 part, hydroxyethyl cellulose as a flocculant (trade name: Cellosize WP-09L, Union Carbide Japan Co., Ltd.) 0.4 part, general blue dye (trade name: Water Blue 117L, 1.1 parts of Orient Chemical Co., Ltd.), 0.4 parts of general yellow dye (trade name: Quinoline Yellow WS300, manufactured by Daiwa Kasei Co., Ltd.), and 47.5 parts of water are uniformly stirred to obtain reversible thermochromic properties. A concealing ink was obtained.
Preparation of writing instrument Using the same member as in Example 2, a writing instrument having a thermochromic reversible concealing function was prepared in the same manner.
Handwriting performance A reversible thermochromic concealing handwriting layer was formed by writing a handwriting of 10 cm length (handwriting width: 4 mm) at a writing speed of 2 seconds on a report paper with the writing tool.
The handwriting layer is black at room temperature (25 ° C.) and turns green when heated to 40 ° C., and the green state is maintained at room temperature. It was restored and the discoloration behavior was repeated and reproduced.
The lightness value in the black state of the handwriting layer was 3.44, and the lightness value in the green state was 5.66. A black reversible thermochromic concealment layer was formed by concealing the black character print image with the above writing tool at the same writing speed as described above at room temperature. It showed possible concealment. Next, when the handwriting layer was rubbed with a friction body equipped on the tip of the cap, the color changed to green, and the character printed image was changed to a legible state, and this state was kept at room temperature. Next, when the temperature was cooled to 25 ° C. or lower, the green handwriting layer was restored to the original black color, and the character print image was kept in an unreadable state again.

Example 4
Preparation of reversible thermochromic hiding ink 6 '-(dipentylamino) -2'-[(3- (trifluoromethyl) phenyl) amino] -spiro [isobenzofuran-1 (3H), 9 '-(9H ) Xanthene] -3-one 7.0 parts, 1,1-bis- (4-hydroxyphenyl) hexafluoropropane 6.0 parts, 1,1-bis (4′hydroxyphenyl) n-decane 10.0 parts Then, a reversible thermochromic composition comprising 50.0 parts of neopentyl stearate is heated and dissolved, and 30 parts of an aromatic isocyanate prepolymer / ethyl acetate solution (prepolymer concentration: 75% by weight) is added as a wall film material, and uniform The solution dissolved in was poured into 100 parts of a 6% by weight polyvinyl alcohol aqueous solution heated to 70 ° C. with stirring, emulsified into fine droplets, and further reacted at 80 ° C. for 5 hours. Ri to obtain a stock solution of microcapsule pigment comprising the reversible thermochromic composition. Subsequently, a reversible thermochromic microcapsule pigment (average particle size: 1.5 μm: t ₁ : 8 ° C., t ₂ : 11 ° C., t ₃ : 29 ° C., t ₄ : 35 ° C.) is obtained by centrifuging the stock solution. Obtained.
35 parts of the reversible thermochromic microcapsule pigment, 15 parts of glycerin, 0.5 part of an antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Co., Ltd.), silicone antifoaming agent (trade name: SN deformer 381) 0.1 part by San Nopco Co., Ltd., 0.4 parts by weight of hydroxyethyl cellulose (trade name: Cellosize WP-09L, Union Carbide Japan Co., Ltd.) as a flocculant, general red dye (trade name: Edible Red 3 No., manufactured by Daiwa Kasei Co., Ltd.) 1.0 part and 48.0 parts of water were uniformly stirred to obtain a temperature-sensitive color-changing hiding ink.
Preparation of writing instrument Using the same member as in Example 2, a writing instrument having a thermochromic reversible concealing function was prepared in the same manner.
Handwriting performance A reversible thermochromic concealing handwriting layer was formed by writing a handwriting of 10 cm length (handwriting width: 4 mm) at a writing speed of 2 seconds on a report paper with the writing tool.
The handwriting layer is black at room temperature (25 ° C.) and changes to pink when heated to 35 ° C., and the pink state is maintained at room temperature. It returned to black and the discoloration behavior was repeated and reproduced.
The lightness value in the black state of the handwriting layer was 3.50, and the lightness value in the pink state was 5.50. A black reversible thermochromic concealment layer was formed by concealing the black character print image with the above writing tool at the same writing speed as described above at room temperature. It showed possible concealment. Next, when the handwriting layer was rubbed with a friction body equipped at the tip of the cap, the color changed to pink, and the character printed image was changed to a legible state, and this state was kept at room temperature. Subsequently, when the temperature was cooled to 8 ° C. or lower, the pink handwriting layer was restored to the original black color, and the character print image was kept in an unreadable state again.

Example 5
Preparation of reversible thermochromic hiding ink Using the reversible thermochromic microcapsule pigment of Example 4, 1.0 part of the general color red dye of Example 4 was replaced with a general color orange dye (trade name: Sunset Yellow FCF, Daiwa Kasei) A reversible thermochromic hiding ink was prepared in the same manner as in Example 4 except that 0.50 part by weight and 48.5 parts of water were used.
Preparation of writing instrument Using the same member as in Example 2, a writing instrument having a thermochromic reversible concealing function was prepared in the same manner.
Handwriting performance A reversible thermochromic concealing handwriting layer was formed by writing a handwriting of 10 cm length (handwriting width: 4 mm) at a writing speed of 2 seconds on a report paper with the writing tool.
The handwriting layer is black at room temperature (25 ° C.) and changes to orange when heated to 35 ° C., and the orange state is maintained at room temperature. It returned to black and the discoloration behavior was repeated and reproduced.
The lightness value in the black state of the handwriting layer was 3.68, and the lightness value in the orange state was 7.59. A black reversible thermochromic concealment layer was formed by concealing the black character print image with the above writing tool at the same writing speed as described above at room temperature. It showed possible concealment. Next, when the handwriting layer was rubbed with a friction body equipped on the tip of the cap, the color changed to orange, and the character printed image was changed to a legible state, and this state was kept at room temperature. Subsequently, when the temperature was cooled to 8 ° C. or lower, the orange handwriting layer was restored to the original black color, and the character print image was kept in an unreadable state again.

It is explanatory drawing of one Embodiment of the writing instrument provided with the thermochromic reversible concealment function of this invention. It is explanatory drawing of other embodiment (double-headed type) of the writing instrument provided with the thermochromic reversible concealment function of this invention. It is a longitudinal cross-sectional explanatory drawing of the concealment state which concealed the printing image or the writing image by the reversible thermochromic concealing handwriting layer which covers the printing image or the writing image. (A) shows the opacity handwriting layer in a colored state, and (B) shows the opacity handwriting layer in a discolored state. It is a graph which shows the relationship of the temperature-color density curve of the reversible thermochromic microcapsule pigment applied to this invention. It is a graph which shows the relationship of the temperature-color density curve of the thermochromic color memory microcapsule pigment applied to this invention. It is a model explanatory drawing of one form of a reversible thermochromic microcapsule pigment. (A) shows an external appearance, and (B) shows a cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Writing instrument provided with thermochromic reversible concealment function 2 Fiber pen body 3 Ball 4 Reversible thermochromic concealing ink 4a Aggregation ink 4b Shear thinning ink 5 Non-thermochromic ink 6 Fiber bundle ink occlusion body 7 Liquid stopper 8 Shaft cylinder 9 Cap 10 Friction body 11 Support 12 Printed image or written image 13 Reversible thermochromic concealing layer (A) Colored state (B) Discolored state (including decolored state)
14 reversible thermochromic microcapsule pigment a wall film b dent c reversible thermochromic composition t ₁ complete color development temperature of heat decolorable thermochromic pigment t ₂ color development start temperature of heat decolorable thermochromic pigment t ₃ Decoloration start temperature of heat decolorable thermochromic pigment t ₄ Complete decolorization temperature of heat decolorable thermochromic pigment

Claims (6)

  By forming a reversible thermochromic concealing handwriting layer that covers a printed image or a written image, the image can be obstructed in the normal temperature range, and the handwriting layer is discolored by frictional heat due to friction of the friction body. A writing instrument having a thermochromic reversible concealment function that reveals an image in a visible state, having a high temperature side complete color change temperature that minimizes color density in a range of 25 to 60 ° C., and an average particle diameter The reversible thermochromic ink in which 10 to 45% by weight of the reversible thermochromic microcapsule pigment in the range of 1 to 6 μm is dispersed in an aqueous medium is allowed to flow out from the writing tip, and the lightness value of the color density in the colored state is A reversible thermochromic concealing handwriting layer having a brightness value of at least 5.0 or more and a lightness value in a color change state by frictional heat of at least 5.0 can be formed, and a friction body for imparting frictional heat due to the rubbing is provided. Writing tool having a thermochromic reversible Inken that features and.   The writing instrument having the thermochromic reversible revelation function according to claim 1, wherein a non-thermochromic colorant is blended in the ink or in the reversible thermochromic microcapsule pigment.   Filling ink storage body consisting of fiber converging body accommodated in shaft barrel with aggregation ink in which reversible thermochromic microcapsule pigment is suspended in gentle aggregation state, it can flow out from fiber pen body consisting of fiber processed body The writing instrument provided with the thermochromic reversible concealment function according to claim 1 or 2, wherein the thermochromic reversible concealment function is provided.   The writing instrument provided with the thermochromic reversible concealment function according to any one of claims 1 to 3, wherein the other end is provided with a writing body that forms a handwriting with a non-thermochromic ink.   The writing instrument having a thermochromic reversible concealment function according to claim 4, wherein the handwriting by the non-thermochromic ink is configured to be concealed by a reversible thermochromic concealing handwriting layer.   6. The writing instrument having a thermochromic reversible concealment function according to claim 5, wherein the handwriting by the non-thermochromic ink and the reversible thermochromic concealing layer at the time of color development exhibit the same or similar hue.

Images