JP5358525B2 - Writing instrument - Google Patents

Description

The present invention relates to a writing instrument such as a ballpoint pen, a sign pen, or a marking pen containing reversible thermochromic ink . More specifically, an image or handwriting formed by a reversible thermochromic ink, to a writing instrument provided with a friction body having elasticity to further discoloration frictional heat.

Conventionally, there has been proposed a thermochromic set including a friction body that discolors a reversible thermochromic layer formed on a support with frictional heat generated by manual friction (see Patent Document 1).
The friction body used in the above proposal is provided with an overcoat layer on the reversible thermochromic layer because the reversible thermochromic layer is peeled off when rubbing to generate frictional heat and the reversible color change is impaired. It is necessary to prevent peeling.
Further, in the exemplified resin used in the rubbing portion of the friction body described in Patent Document 1, since the resin itself is scraped by rubbing, a residue may be produced and the surroundings may be soiled. Furthermore, the number of scratches may increase due to the low generation efficiency of frictional heat.
Further, since the reversible thermochromic layer of Patent Document 1 is provided with an overcoat layer for preventing peeling of the rubbing part of the reversible thermochromic image, it is only possible to discolor the existing reversible thermochromic image. The reversible thermochromic image freely formed by the user could not be discolored.

JP-A-7-241388

The present invention solves the above-mentioned problems, does not require a protective member such as an overcoat layer, can be discolored without peeling off images and handwriting formed with reversible thermochromic ink, and wear due to friction. An object of the present invention is to provide a writing instrument provided with a friction body that is difficult to wake up and has high durability due to repeated use.

The present invention is a writing instrument containing at least a reversible thermochromic ink, wherein the reversible thermochromic ink contains a microcapsule pigment having an average particle diameter in the range of 0.5 to 5.0 μm as an aqueous solvent. The microcapsule pigment has a high temperature side discoloration point in the range of 25 to 65 ° C., and the writing instrument has a friction body made of an elastic body at the rear end of the shaft tube. The friction body has a convex curved rubbing portion having a curvature radius R of 1 mm to 10 mm, and the reversible thermochromic property formed on the paper having permeability by friction heat when rubbing by manual operation. The ink image or handwriting is heated to the predetermined temperature or more to change the color from the first coloring state to the second coloring state, from the coloring state to the decoloring state, or from the decoloring state to the coloring state.
Preferably, the friction body contains a colorant so that the friction body is colored in at least one ink color before and after the color change, and is configured as a color display function part that notifies at least one ink color before and after the color change. The colorant is contained in an amount of 0.1 to 1.0% by weight in the total amount of the friction body. More preferably, the friction body may be made of silicone rubber.
Preferably, it is good also as a structure which penetrated the ventilation hole or ventilation groove in the said friction body.

The present invention will be described with reference to the drawings (see FIGS. 1 to 6).
Friction body 1 of the present invention is intended to be discolored more easily the image or handwriting formed by the reversible thermochromic ink 6 to frictional heat, tautomeric to normal color different by scraping an image or handwriting To change the color.
As the friction body 1, silicone rubber is preferably used.

Further, since the friction body 1 of the present invention can generate heat by manual operation without using power or the like, it can be manufactured at a low cost without requiring a large-scale device, and the writing instrument 2 incorporating the reversible thermochromic ink 6 is used. It can be used by fitting or two-color molding at the rear end of the shaft cylinder 5 or the top of the writing instrument cap 3 . It is possible to form a free image or handwriting by the writing instrument 2 may readily discolor the image or handwriting using the friction body 1.
As the friction body 1 provided on the writing instrument 2, a general-purpose elastic body can be used, but silicone rubber is preferable.

The silicone rubber can be repeatedly and reversibly discolored without peeling off the thermochromic image, whereas the eraser and other rubbers have a high erasing power when rubbed, so the rubbing part of the thermochromic image Will peel off and the discoloration effect will be impaired. Therefore, when the eraser or other rubber is used, it is preferable to provide a coating layer or the like to protect the image.
The silicone rubber has good heat generation efficiency, and the silicone rubber itself is difficult to be scraped off. Therefore, it is possible to easily discolor a thermochromic image without the need to scrape many times, and the periphery of the scraped portion is soiled by scraping scraps. Can be used without In addition, since the resistance at the time of rubbing is small, it can be rubbed smoothly.

Further, a coloring agent can be added to the friction body 1. By coloring the friction body 1, it becomes rich in design. In addition, when the friction body 1 is mounted on the writing instrument 2, it is colored in the ink color of the first state or the second state, and is a color display function part that informs the user of the color that appears due to the color of the first state or the discoloration. , a unified design can Figure Rukoto by colored to match the writing instrument 2 exterior.
The amount of the colorant added is preferably 0.1 to 1.0% by weight in the total amount of the friction body 1. If it is less than 0.1%, the friction body 1 cannot be clearly colored, and if it exceeds 1.0%, the colorant moves around the handwriting when it is rubbed.
In general, general-purpose dyes, pigments, and the like can be appropriately used as the colorant.
Furthermore, various additives such as a filler can be added to the friction body 1 as necessary.

Further, in the friction body 1 attached to the writing instrument 2, the shape of the rubbing portion 11 is a convex curved surface . By using a convex curved surface, it can be rubbed with moderate softness without peeling off the handwriting. In addition, a constant contact area can be obtained regardless of the contact angle with the handwriting, and only the target part can be abraded without rubbing a wide area, the wearability of the friction body 1 itself can be reduced, and the heat generation efficiency is increased. Therefore, it is possible to accurately and easily change the color of the portion to be changed without scraping off.
Further, by setting the radius of curvature R of the convex curved surface within a range of 1 mm to 10 mm, the narrow handwriting formed by the writing instrument 2 can be discolored accurately and easily.

  Further, when the outer diameter D and the protruding length L of the friction body 1 attached to the writing instrument 2 satisfy L <D, the friction body 1 can be prevented from wobbling or falling off at the time of rubbing, resulting in a rubbing failure. Nothing will happen. The outer diameter D and the protruding length L preferably satisfy 0.25 ≦ L / D ≦ 0.85.

  Furthermore, by setting the pulling force of the friction body 1 to 10 N or more, the friction body 1 cannot be easily removed from the writing instrument 2, and accidental ingestion by an infant or the like can be prevented. When attaching the friction body 1 to the writing instrument 2, a locking rib 32 may be provided on the inner surface of the friction body fitting portion 31 of the writing instrument 2 for the purpose of improving the removal force.

  In addition, when the friction body 1 satisfies L <D between the outer diameter D and the protruding length L, and the pulling force is 10 N or more, the friction body 1 does not wobble or fall off during rubbing. Since it cannot be easily removed when pulled, the applicability as a product is high.

  Further, by providing a ventilation hole or a ventilation groove in the friction body 1, even if an infant or the like swallows it, the safety becomes higher.

Next, the reversible thermochromic ink 6 will be described.
The reversible thermochromic ink 6 that forms a reversible thermochromic image and handwriting reversibly discolored by the friction body 1 of the present invention is decolored by heating from the colored state and restored to the colored state by cooling from the decolored state. Heating decoloring type, color memory holding type that holds the colored state or decoloring state interchangeably in a specific temperature range, or color development by heating from the decoloring state, and decoloring state by cooling from the coloring state Images that are rich in magic, such as images that change color due to rubbing, return to their original colors instantly, and those that can retain color change due to rubbing over a wide temperature range by being composed of various types, such as a heat coloring type that recovers. Can be formed. Further, the reversible thermochromic ink 6 has a normal state (daily life) by specifying a minimum low temperature side color change point in a range of −30 ° C. to + 10 ° C. and a maximum high temperature side color change point in a range of 36 ° C. to 65 ° C. The color retention exhibited in the living temperature range) can be effectively functioned and is highly practical.

In addition, the reversible thermochromic microcapsule pigment contained in the reversible thermochromic ink 6 incorporated in the writing instrument 2 is a conventionally known (a) electron donating color-forming organic compound, (b) an electron accepting compound. And (c) a reversible thermochromic composition containing at least the essential three components of the reaction medium for determining the occurrence temperature of the color reaction of both of them is effective, and it is effective to encapsulate in a microcapsule. As the heat erasing type that is decolored by heating, those described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, etc. proposed by the present applicant can be used. . The color changes before and after a predetermined temperature (discoloration point), exhibits a decolored state in a temperature range above the complete decoloring temperature, and develops a color state in a temperature range below the complete color developing temperature. There is only one specific state in the region. 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.).
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 complete decoloring temperature (t ₄₎ and sharply sensitive to show the discoloration of sensitive to temperature changes in the boundary of complete coloring temperature (t _1), after the color change in [Delta] H _a is 4 to 7 ° C. about the system, slow Returning to the original aspect, the visual effect can be enhanced (see FIG. 5).
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 very different path from the case of lowering the color, and the color develops in the low temperature range below the complete color development temperature (t ₁ ) or the color erases in the high temperature range above the complete color erase temperature (t ₄ ). A color memory-holding thermochromic composition that can be stored in a specific temperature range [temperature range between t _{2 and} t ₃ (substantially two-phase holding temperature range)] can also be applied (see FIG. 6).
The substantial two-phase holding temperature range can be set according to the purpose, but in the present invention, the high temperature side discoloration point is set in a range of 25 ° C. to 65 ° C. (preferably 36 ° C. to 65 ° C.).
The minimum low temperature side discoloration point [complete color development temperature (t ₁ )] can be set to any temperature selected from the range of −30 ° C. to + 20 ° C. (preferably −30 ° C. to + 10 ° C.).
By the temperature setting, the color development state or the color erasure state can be stored in an alternating manner at any temperature between the color development start temperature (t ₂ ) and the color erasure start temperature (t ₃ ) and can be visualized.
Further, as a heat-colorable composition, a specific color having a linear or side chain alkyl group having 3 to 18 carbon atoms as an electron-accepting compound proposed by the present applicant, which develops color when heated from a decolored state. A system to which an alkoxyphenol compound is applied (JP-A-11-129623, JP-A-11-5973) or a system to which a specific hydroxybenzoic acid ester is applied (JP-A-2001-105732), and further decoloring A system using gallic acid ester or the like that develops color at the maximum high temperature side color change point (complete color development temperature) by heating from the state can be applied.
Here, a colorant such as a non-thermochromic dye or pigment is blended in the reversible thermochromic microcapsule or the ink so as to change the color from color (1) to color (2). It can be configured to present.

The microcapsule pigment has an average particle diameter in the range of 0.5 to 5.0 μm, preferably 1 to 4 μm. When the average particle diameter exceeds 5.0 μm, the outflow from the capillary gap is reduced, and when the average particle diameter is less than 0.5 μm, it is difficult to exhibit high color density.

  The reversible thermochromic microcapsule pigment can be blended in an amount of 2 to 50% by weight (preferably 3 to 40% by weight, more preferably 4 to 30% by weight) based on the total amount of the ink composition. If it is less than 2% by weight, the color density is insufficient, and if it exceeds 50% by weight, the ink outflow is reduced and the writing property is impaired.

The form of the capsule in the reversible thermochromic microcapsule pigment of the present invention does not refuse application of a circular cross-sectional form, but a non-circular cross-sectional form is effective.
The reversible thermochromic handwriting formed by writing, the microcapsule pigment is densely oriented and fixed, showing a high concentration of color development, and against the external force due to rubbing the handwriting by the friction body 1, etc. The microcapsule pigment is subtly elastically deformed into a shape that relaxes external force, the destruction of the wall film of the microcapsule is suppressed, and the microcapsule pigment can be effectively expressed without impairing the thermochromic function.
Here, the non-circular cross-sectional shape microcapsule pigment preferably satisfies the range of reversible thermochromic composition / wall film = 7/1 to 1/1 (weight ratio) .
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). .

  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, and a coacervate method can be applied, but the particle size satisfying the above-described requirements of the present invention In order to obtain a microcapsule pigment in the range, it is effective to apply an interfacial polymerization method or an interfacial polycondensation method that hardly causes aggregation or coalescence.

Here, the reversible thermochromic microcapsule pigment or the ink is blended with a colorant such as a non-thermochromic dye or pigment to change the color from color (1) to color (2). It is set as the structure which exhibits.
As the dye, acid dyes, basic dyes, direct dyes and fluorescent dyes can all be used.
Examples of pigments include inorganic pigments such as carbon black, ultramarine and titanium dioxide pigments, azo pigments, phthalocyanine pigments, indigo pigments, thioindigo pigments, selenium pigments, quinacridone pigments, anthraquinone pigments, stron pigments, diketopyrrolopyrrole. Examples thereof include organic pigments and fluorescent pigments such as pigments, dioxazine pigments, perylene pigments, perinone pigments, and isoindolinone pigments.

The reversible thermochromic ink 6 incorporated in the writing instrument 2 of the present invention has a maximum high temperature side color change point in a range of 25 to 65 ° C. and a reversible thermochromic property in an average particle diameter of 0.5 to 5 μm. It is effective to disperse the microcapsule pigment in an aqueous medium and blend a binder resin as necessary.
Specifically, a shear-thinning ink containing a shear-thinning substance and an agglomerated ink in which a reversible thermochromic microcapsule pigment is suspended in a gentle agglomerated state with a water-soluble polymer flocculant are effective. . Furthermore, 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 with respect to the aqueous vehicle can also be applied.

The shear thinning material 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 of about 100 to 8 million), guar gum, locust bean gum and its derivatives, hydroxyethyl cell row scan, alginate alkyl esters, polymers of molecular weight from 100,000 to 150,000 mainly composed of alkyl esters of methacrylic acid, glucomannan, agar Ya Examples include carbohydrates having gelling ability extracted from seaweed such as carrageenin, benzylidene sorbitol and benzylidene xylitol or their derivatives, cross-linkable 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.

As the water-soluble 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, hydroxy Examples thereof include propylmethylcellulose. 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.

Further, as a moisturizing agent 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, An appropriate amount of urea or the like can be blended.
The humectant can be blended in an amount of 5 to 40% by weight based on the total amount of ink.

Furthermore, an appropriate amount of a binder resin can be added to adjust the stickiness of the handwriting and 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.

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

The shear-thinning ink and the aggregation ink are filled in a general-purpose writing instrument 2 and put to practical use.
Specifically, the shear-thinning ink is filled in a shaft cylinder 5 provided with a tip that rotatably holds a ball at the tip, and a viscous follower (liquid stopper 7) is arranged at the rear. A thermochromic writing instrument 2 in the form of a ballpoint pen can be configured. In addition, in the aggregation ink, a large number of fibers are arranged in close contact with each other, and a processed fiber body in which a capillary gap is formed between adjacent fibers is used as a pen body 4, and a capillary gap is formed between adjacent fibers. fiber bundle of the the ink occlusion body, the rear end of the pen body 4 by impregnating the flocculation system ink assembled et marker in a connected state to the front end of the ink occlusion body, markers form of thermochromic writing instrument 2 Can be configured.

In the writing instrument provided with the friction body of the present invention, the user can freely form an image or handwriting of reversible thermochromic ink and can easily change the color of the image or handwriting using the friction body.
  Particularly, by making the shape of the rubbing part of the friction body a convex curved surface, it can be abraded with moderate softness without peeling off the handwriting. In addition, a constant contact area can be obtained regardless of the contact angle with the handwriting, and only the target part can be abraded without rubbing a wide area, the wearability of the friction body itself can be reduced, and the heat generation efficiency is increased. Therefore, it is possible to accurately and easily discolor a portion to be discolored without scraping off. Furthermore, by setting the curvature radius R of the convex curved surface in the range of 1 mm to 10 mm, the narrow handwriting formed by the writing instrument can be accurately and easily discolored.
  In addition, the average particle diameter of the microcapsule pigment contained in the reversible thermochromic ink is 0.5 to 5.0 μm, and the high temperature side color change point is in the range of 25 to 65 ° C. It has color developability and can be reliably changed in color by rubbing.

According to the writing instrument of the present invention according to claim 2, the friction body containing the colorant can be a color display function part that informs the user of at least one ink color before and after the color change.

According to the writing instrument of the present invention according to claim 3, the friction body is vividly colored, and the thermochromic image can be discolored without being transferred to the thermochromic image and its peripheral portion at the time of rubbing.

According to the writing instrument of the present invention according to claim 4, since the frictional body is made of silicone rubber, the wearability of the frictional body itself can be reduced and the heat generation efficiency is increased, so that the image of the reversible thermochromic ink or The handwriting can be easily discolored without rubbing it many times, and can be reversibly discolored repeatedly without peeling off the image or handwriting. Moreover, it can be smoothly rubbed with moderate softness, and can be used without scraping around the rubbed part due to scraping scraps.

Here, when the outer diameter D and the projecting length L of the friction body are set to L <D when attached to the top of the cap or the rear end of the shaft cylinder, the friction body is prevented from wobbling or falling off when it is rubbed. And no flaws occur. Moreover, if the pulling-out force of the friction body attached to the top part of the cap or the rear end of the shaft cylinder is 10 N or more, the friction body cannot be easily removed from the writing instrument, and accidental ingestion by an infant or the like can be prevented. At the same time, when L <D is satisfied, the friction body does not sway or fall off at the time of rubbing, and does not easily come off when pulled, so that applicability as a product is high.

In claim 5, by providing a ventilation hole or ventilation groove in the friction body, even if an infant or the like swallows it, the safety becomes higher.

It is a longitudinal cross-sectional view which shows one Example of the writing instrument provided with the friction body of this invention. It is a principal part enlarged view of FIG. It is AA sectional drawing of FIG. It is explanatory drawing which shows one Example of the writing instrument provided with the friction body of this invention. It is explanatory drawing which shows the discoloration behavior of a heat decoloring type thermochromic ink. It is explanatory drawing which shows the discoloration behavior of a color memory retention type thermochromic ink.

Examples are shown below, but the present invention is not limited to these examples.
The writing instrument 2 is a general-purpose writing instrument 2 such as a ballpoint pen, a sign pen, or a marking pen. The reversible thermochromic ink 6 is provided for practical use. And a cap 3 (see FIG. 1) to which the friction body 1 is attached (see FIG. 4).

  Examples are shown below. In addition, the part in an Example is a weight part.

Example 1
Purple pigment [manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-Color R2301] 0.09 part, red pigment [manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-Color X-93-942] 0.13 After kneading a silicone material with an added part [manufactured by Toray Dow Corning Silicone Co., Ltd., trade name: DY32-7040U], the resulting mixture was molded to obtain a red friction body 1.
The friction body 1 could instantly change the color of the reversible thermochromic image printed on the paper surface by rubbing and did not transfer the color to the paper surface.

Example 2
Preparation of reversible thermochromic ink 6 A reversible thermochromic pigment (t ₁ : 2 ° C., t ₂ : 6 ° C., t ₃ : 37 ° C., t ₄ : encapsulated in a thermosensitive color-changing color memory composition. 44 ° C., average particle size: 2.5 μm, reversible thermochromic composition / wall film = 2.6 / 1.0, color change from dark green to colorless) 12.5 parts, temperature-sensitive color-change color memory Reversible thermochromic pigment in which the composition is encapsulated in microcapsules (t ₁ : 3 ° C., t ₂ : 6 ° C., t ₃ : 38 ° C., t ₄ : 45 ° C., average particle size: 2.5 μm, reversible thermochromic property Composition / wall film = 2.6 / 1.0, color change from blue to colorless) 5.5 parts, red dye [manufactured by Eisen Hodogaya Co., Ltd., trade name: New Coxin, C.I. I. 16255] 0.25 parts, xanthan gum (shear thinning agent) 0.33 parts, urea 10 parts, glycerin 10 parts, nonionic permeability imparting agent [manufactured by San Nopco Co., Ltd., trade name: Nopco SW-WET-366 0.6 parts, modified silicone antifoaming agent [manufactured by Sannopco, trade name: Nopco 8034] 0.1 part, antifungal agent [manufactured by Zeneca, trade name: Proxel XL-2] A reversible thermochromic ink consisting of 1 part and 60.62 parts of water was prepared (FIG. 6).

Preparation of a writing instrument 0.97 g of the ink (previously cooled to 2 ° C. or lower and allowed to develop a reversible thermochromic pigment, and then allowed to stand at room temperature) is sucked and filled into a polypropylene pipe having an inner diameter of 4.4 mm. It connected with the ball-point pen tip which hold | maintained the 0.7 mm stainless steel ball | bowl at the front-end | tip through the holder made from.
Next, an ink backflow prevention body (liquid stopper 7) having viscoelasticity mainly composed of polybutene is filled from the rear part of the polypropylene pipe, assembled in the shaft cylinder 5, and the friction body 1 produced in Example 1 is obtained. A cap 3 having a convex curved surface with a curvature radius of 3.0 mm, a pulling force of 10 N, an outer diameter D and a protruding length L of L / D = 0.48 and fitted to the top is attached, and then removed by centrifugation. Air treatment was performed to obtain a shear thinning thermochromic ballpoint pen (FIG. 1).
When writing on the report paper with the ball-point pen, the handwriting was not erased even by writing for a long time or shorthand, and a clear thermochromic handwriting of black having a stable density was obtained.

Discoloration behavior of handwriting The thermochromic handwriting written on paper having normal penetrability with the ballpoint pen is in a black colored state at room temperature (25 ° C.), and when it is rubbed with the friction body 1 several times, the rubbed part Immediately changed color to red, and this state could be maintained at room temperature. Then, upon standing the thermochromic handwriting in a freezer (approximately -15 ° C.), the red color portion is returned to the state before color abraded again black. This discoloration behavior could be reproduced repeatedly.

Example 3
Preparation of reversible thermochromic ink 6 Heat decoloring type reversible thermochromic microcapsule pigment (t ₁ : 35 ° C., t ₂ : 38 ° C., t ₃ : 37 ° C., t ₄ : 40 ° C., average particle size: 2. 5 μm, reversible thermochromic composition / wall film = 2.6 / 1.0, changing color from blue to colorless) 44.00 parts (solid content 13.2%) of pink dye [ Eisen Hodogaya Co., Ltd., trade name: Erythrosin (CI No. 45430)] 0.50 parts, glycerin 5.00 parts, antifungal agent, [Zeneca Co., Ltd. trade name: Proxel XL- 2] 0.70 part, silicone-based antifoam, [manufactured by San Nopco Co., Ltd., trade name: SN deformer 381] uniformly dispersed in an aqueous medium consisting of 0.1 part and 41.70 parts of water Water soluble polymer flocculant (hydroxyethyl cellulose) [ Union Carbide Japan Co., Ltd., trade name: Serosize WP-09L] 8.00 parts by weight of an aqueous solution containing 5.00% by weight is added to the liquid in the dispersed state while stirring, and the reversible thermochromic property. A reversible thermochromic ink 6 in which the microcapsule pigment was suspended in a gentle aggregate state was prepared.

Preparation of Writing Tool 2 A reversible thermochromic ink 6 was impregnated immediately after stirring in a uniform state in a fiber sizing ink occlusion body (porosity of about 80%) covered with a polyester resin sliver, and Example 1 The friction body 1 obtained in the above is a convex curved surface having a curvature radius of 4.0 mm, and the outer diameter D and the protruding length L are accommodated in a shaft cylinder 5 formed at the rear end portion with L / D = 0.63. The water-based marker was constructed by assembling the polyester fiber resin processing pen body 4 (porosity of about 50%) attached to the tip of the shaft cylinder 5 in contact.
When writing on the report paper with the water-based marker, the handwriting was not discolored even with long-time writing or shorthand writing, and a clear, clear purple-colored handwriting with a stable color tone was obtained.

Discoloration behavior of handwriting The handwriting written on paper having normal penetrability with the water-based marker is in a purple discoloration state at room temperature (25 ° C.). The color changed to pink. Further, when left in this discolored state at room temperature, the pink color portion changed to purple again and returned to the state before rubbing. The discoloration behavior could be reproduced repeatedly.

DESCRIPTION OF SYMBOLS 1 Friction body 11 Abrasion part 2 Writing implement 3 Cap 31 Fitting part 32 Rib 4 Pen body 5 Shaft cylinder 6 Reversible thermochromic ink 7 Liquid stopper 8 Refill t ₁ Heat decoloring type thermochromic ink and color memory retention type thermochromic Color development temperature (minimum temperature change point)
t ₂ Coloring start temperature of heat-erasable color-changing ink and color memory retention-type thermochromic ink t ₃ Color-development starting temperature of heat-erasing color-coloring ink and color memory retention-type thermochromic ink t ₄ Heating Full color erasing temperature (maximum high temperature side color change point) of erasable thermochromic ink and color memory retention thermochromic ink

Claims (5)

A writing instrument containing at least a reversible thermochromic ink,
The reversible thermochromic ink has a structure in which a microcapsule pigment having an average particle size in the range of 0.5 to 5.0 μm is dispersed in an aqueous solvent. Has a high temperature side discoloration point in the range of ℃,
The writing instrument includes a friction body made of an elastic body at a rear end portion of the shaft cylinder. The friction body has a rubbing portion having a convex curved surface with a radius of curvature R of 1 mm to 10 mm, and is rubbed by manual operation. The reversible thermochromic ink image or handwriting formed on the paper having permeability by frictional heat is heated to the predetermined temperature or more, and the first coloring state to the second coloring state or the coloring state to the decoloring state. Or , a writing instrument that changes color from a decolored state to a colored state . By containing a colorant in the friction body , the friction body is colored in at least one ink color before and after the color change, and is a color display function part that notifies at least one ink color before and after the color change. The writing instrument according to claim 1 . 3. The writing instrument according to claim 2 , wherein the colorant is contained in an amount of 0.1 to 1.0% by weight in the total amount of the friction body. The writing instrument according to claim 1 , wherein the friction body is made of silicone rubber. The writing instrument according to claim 1, wherein a ventilation hole or a ventilation groove is provided through the friction body.

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