JP2008290392A - Rubbing body, writing utensil, and writing utensil set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubbing body which enbles anybody, regardless of age or sex, to surely and easily heat-discolor a heat-discoloring image or handwriting by frictional heat. <P>SOLUTION: This rubbing body 7 rubs the heat-discoloring image or the handwriting being formed on a paper surface by using a heat-discoloring ink, and makes the heat-discoloring image or hand writing heat-discolor by the frictional heat being generated at the time of rubbing. The thermal conductivity of the rubbing section of the rubbing body 7 is set to be in a range of 0.05 W/(m×K) to 50 W/(m×K). The frictional coefficient of the rubbing section of the rubbing body 7 to the paper surface is set to be in a range of 0.2 to 1.0. This writing utensil is equipped with the rubbing body 7 as a part of the writing utensil which internally contains the heat-discoloring ink, and can discharge the heat-discoloring ink. Also, this writing utensil set is formed by combining the rubbing body and the writing utensil which internally contains the heat-discoloring ink, and can discharge the heat-discoloring ink. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a friction body capable of thermally discoloring a thermochromic image or handwriting with frictional heat, a writing instrument including the friction body, and a writing instrument set in which the friction body and the writing instrument are combined.

Conventionally, for example, there are Document 1 and Document 2 regarding elastic friction bodies that change the color of an image formed using reversible thermochromic ink from a first state to a second state by frictional heat.

JP 2004-148744 A JP 2006-123324 A

In the conventional friction body, there is still room for improvement in order to reliably and easily discolor thermochromic images or handwriting by frictional heat by manual friction, regardless of age or sex.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and an object is to provide a friction body capable of reliably and easily thermally discoloring a thermochromic image or handwriting with frictional heat regardless of age or sex. To do.

The inventor of the present invention pays attention to the thermal conductivity of the friction part of the friction body and, as a result of intensive research, sets the thermal conductivity of the friction part of the friction body to a specific range, thereby obtaining an image of thermal discoloration. Alternatively, it has been found that the handwriting can be surely thermally discolored by the frictional heat of the friction body.

1st invention of this application rubs the thermochromic image or handwriting formed on the paper surface using thermochromic ink, and heat-discolors the said thermochromic image or handwriting with the frictional heat which arises in that case It is a friction body, and it is a requirement that the thermal conductivity of the friction portion of the friction body is set in a range of 0.05 W / (m · K) to 50 W / (m · K).

By setting the friction body of the first invention in the range of 0.05 W / (m · K) to 50 W / (m · K), anyone regardless of age or sex can make a thermochromic image or handwriting. Thermal discoloration can be reliably and easily caused by frictional heat generated by manual friction.

When the thermal conductivity of the friction part of the friction body exceeds 50 watts per meter Kelvin (W / (m · K)), for example, in an elderly person or a child, There is a possibility that the handwriting cannot be reliably thermally discolored. On the other hand, when the thermal conductivity of the friction part of the friction body is smaller than 0.05 watts per meter Kelvin (W / (m · K)), the friction bodies and the paper surface may be damaged by overheating.

According to a second invention of the present application, in the first invention, the thermal conductivity of the friction portion of the friction body is set in a range of 0.05 W / (m · K) to 20 W / (m · K). Is a requirement.

By setting the friction body of the second invention in a range of 0.05 W / (m · K) to 20 W / (m · K), any person regardless of age or sex can make a thermochromic image or handwriting. Thermal discoloration can be reliably and easily caused by frictional heat generated by manual friction.

When the thermal conductivity of the friction part of the friction body exceeds 20 watts per meter Kelvin (W / (m · K)), for example, in an elderly person or a child, There is a possibility that the handwriting cannot be reliably thermally discolored. On the other hand, when the thermal conductivity of the friction portion of the friction body is smaller than 0.05 watts per meter Kelvin (W / (m · K)), the friction bodies and the paper surface may be damaged by overheating.

According to a third invention of the present application, in the first invention, the thermal conductivity of the friction portion of the friction body is set in a range of 0.05 W / (m · K) to 20 W / (m · K). Is a requirement.

By setting the friction body of the third invention in the range of 0.05 W / (m · K) to 10 W / (m · K), anyone regardless of age or sex can make a thermochromic image or handwriting. Thermal discoloration can be reliably and easily caused by frictional heat generated by manual friction.

When the thermal conductivity of the friction part of the friction body exceeds 10 watts per meter Kelvin (W / (m · K)), for example, in an elderly person or a child, There is a possibility that the handwriting cannot be reliably thermally discolored. On the other hand, when the thermal conductivity of the friction part of the friction body is smaller than 0.05 watts per meter Kelvin (W / (m · K)), the friction bodies and the paper surface may be damaged by overheating.

In the first, second, and third inventions, the thermal conductivity is measured using an AUTOΛ (HC-072) manufactured by Eihiro Seiki, a pressing force of 250 kg / m ² , a high temperature plate temperature of 35 ° C., and a low temperature plate temperature of 5 ° C. Measured with The unit of thermal conductivity is watts per meter Kelvin (W / (m · K)). In the first, second, and third inventions, the friction part of the friction body is a part that generates frictional heat in contact with the thermochromic image or handwriting on the paper surface.

4th invention of this application requires that the friction coefficient with respect to the paper surface of the friction part of the said friction body was set to the range of 0.2-1.0 in the said 1st, 2nd or 3rd invention. And

In the friction body according to the fourth aspect of the present invention, the coefficient of friction with respect to the paper surface of the friction portion of the friction body is set in the range of 0.2 to 1.0, thereby further ensuring a thermochromic image or handwriting. And it can be easily discolored by heat.

When the friction coefficient of the friction part with respect to the paper surface of the friction body is smaller than 0.2, even if the friction is caused by a large load, the thermochromic image or handwriting cannot be easily discolored. On the other hand, if the friction coefficient of the friction part with respect to the paper surface of the friction body is greater than 1.0, the frictional resistance with the paper surface during friction may be too large, and smooth manual friction may be difficult, or the paper surface may be damaged. There is.

In addition, the said friction coefficient (dynamic friction coefficient) is 100 mm / min using a surface property measuring machine: HEIDON-14D manufactured by Shinto Kagaku Co., Ltd., and writing paper A (load of 500 g (4.9 N)). Old JIS P3201: High-quality paper made from 100% chemical pulp as raw material, weighing range of 40 to 157 g / m ² , whiteness of 75.0% or more) Measure friction coefficient (friction force / load) when rubbing did.

According to a fifth aspect of the present invention, there is a requirement for a writing instrument including the friction body according to any one of the first to fourth aspects as a part of a writing instrument that incorporates a thermochromic ink and is capable of discharging the thermochromic ink. And

According to the fifth aspect of the present invention, a thermochromic image or handwriting formed by a writing instrument can be reliably and easily thermally discolored by friction of a friction body provided in a part of the writing instrument.

The sixth invention of the present application requires a writing instrument set comprising the friction body according to any one of the first to fourth inventions, and a writing instrument that incorporates thermochromic ink and is capable of discharging thermochromic ink. .

In the sixth aspect of the present invention, the thermochromic image or handwriting formed by the writing instrument can be reliably and easily thermally discolored by the friction of the friction body combined with the writing instrument.

Friction body In the first, second, third, fourth, fifth, and sixth inventions, the friction body may be made of any material such as glass, metal, stone, resin, etc. Resin, styrene resin (styrene / butadiene copolymer, styrene / ethylene / butadiene copolymer), fluorine resin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM), polypropylene, polyethylene Synthetic resins such as

It is preferable that the friction body includes a thermochromic ink therein and is provided in a part of a writing instrument that can eject the thermochromic ink from the pen tip. The configuration in which the friction body is provided on a part of the writing instrument includes, for example, a configuration in which the friction body is provided on the side opposite to the pen tip of the writing instrument body, or a configuration in which the friction body is provided on the top of the removable cap on the pen tip side of the writing instrument body Etc. The friction body may be combined with a writing instrument that incorporates a thermochromic ink therein and discharges the thermochromic ink from a pen tip to form a writing instrument set. Further, the friction body may be configured to directly grip the outer peripheral surface during friction, or may be configured to grip the friction body via the friction body holder.

Writing instrument The pen tip of the writing instrument has, for example, a pen body made of a ballpoint pen tip, a fiber processed body or a porous processed body, a pen body made of a synthetic resin extruded body having an axial capillary passage, and a slit at the tip. Examples thereof include a metal plate pen body and a brush pen body. Examples of the writing instrument include a direct liquid type in which thermochromic ink is directly accommodated, or a batting type in which a thermochromic ink is impregnated in an ink occlusion body.

-Thermochromic ink In the present invention, the thermochromic ink is preferably a reversible thermochromic ink. The reversible thermochromic ink is a heat decoloring type that decolors by heating from a colored state, a color memory retaining type that reversibly stores and retains a colored state or a decolored state in a specific temperature range, or from a decolored state Various types such as a heating coloring type that develops color by heating and returns to a decolored state by cooling from the colored state can be used alone or in combination.

The coloring material contained in the reversible thermochromic ink includes conventionally known (a) electron donating color-forming organic compounds, (b) electron-accepting compounds, and (c) color reactions of both. A reversible thermochromic microcapsule pigment in which a reversible thermochromic composition containing at least three essential components of a reaction medium for determining the occurrence temperature of the microcapsule is preferably used.

In the present invention, as shown in FIG. 8, the shape of the curve plotting the change in color density due to the temperature change is opposite to the case where the temperature is raised from the lower temperature side than the color change temperature range, and from the higher temperature side than the color change temperature range. The color changes by following a different path depending on the descending state, and the color development state in the 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 ) It is preferable to apply a color memory retention type thermochromic ink that can be stored and retained in a specific temperature range [temperature range between t _{2 and} t ₃ (substantially two-phase retention temperature range)]. In FIG. 8, ΔH represents a temperature width (ie, hysteresis width) indicating the degree of hysteresis. When the value of ΔH is small, only one of the two states before and after the color change can exist. When the value of ΔH is large, it is easy to maintain each state before and after the color change.

In the present invention, the color change temperature due to frictional heat of the friction body of the thermochromic ink is set to 25 ° C. to 95 ° C. (preferably 36 ° C. to 95 ° C.). That is, in the present invention, the high temperature side discoloration point [complete decoloring temperature (t ₄ )] is set in a range of 25 ° C. to 95 ° C. (preferably 36 ° C. to 90 ° C.), and the low temperature side discoloration point [ It is effective to set the complete color development temperature (t ₁ )] in the range of −30 ° C. to + 20 ° C. (preferably −30 ° C. to + 10 ° C.). Accordingly, it is possible to effectively maintain the color exhibited in the normal state (daily life temperature range), and it is possible to easily change the color of the image or handwriting by the reversible thermochromic ink by the frictional heat generated by the friction body.

The reversible thermochromic microcapsule pigment preferably 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 of the ballpoint pen tip or the porous pen body decreases, and when the average particle diameter is 0.5 μm or less, it is difficult to show high density color development. .

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.

According to the friction body of the present invention, regardless of age or sex, anyone can easily and reliably thermally discolor a thermochromic image or handwriting.

<First Embodiment>
A first embodiment of the present invention will be described (see FIG. 1).
The present embodiment is a writing instrument 1 including a writing instrument body 2, a cap 6 that is detachable on the pen tip side of the writing instrument body 2, and a friction body 7 that is attached to the rear end of the writing instrument body 2. A thermochromic ink 4 is built in the writing instrument body 2, and the thermochromic ink 4 is ejected from the pen tip 3. By contact between the pen tip 3 of the writing instrument body 2 and the paper surface, a thermochromic image or handwriting is obtained on the paper surface. By rubbing the image or handwriting formed on the paper surface with the friction body 7, the thermochromic image or handwriting can be discolored thermally.

The writing instrument body 2 includes a pen tip 3 made of a ballpoint pen tip, a pen tip holder 22 with the pen tip 3 fixed to the front end, an ink containing cylinder 23 with the pen tip holder 22 fixed to the front end, and the ink It comprises a tail plug 24 provided with a vent hole attached to the rear end opening of the storage cylinder 23, and a shaft cylinder 21 for storing the ink storage cylinder 23 therein. Housed in the ink storage cylinder 23 are a thermochromic ink 4 and a follower 5 that is disposed at the rear end of the thermochromic ink 4 and moves forward as the thermochromic ink 4 is consumed.

A ball is rotatably held at the front end of the nib 3. A bullet 31 (coil spring) is accommodated in the nib 3, the ball is urged forward by the bullet 31, and the ball is placed on the inner surface of the inward front end edge of the nib 3. Press contact.

A nib seal member 61 made of a soft material is accommodated in the cap 6. When the cap 6 is mounted on the nib side, the nib 3 is in close contact with the nib seal member 61 and the nib 3 is sealed. The

The shaft cylinder 21 includes a front shaft 21a and a rear shaft 21b that are screwed together. The pen tip 3 protrudes from the front end hole of the shaft cylinder 21 (front shaft 21a). A friction body 7 made of a soft synthetic resin is attached to a rear end hole of the shaft cylinder 21 (rear shaft 21b). An outward projection 71 is formed on the outer surface of the friction body 7, an inward projection 21 c is formed on the inner surface of the rear end hole of the shaft cylinder 21, and the outward projection 71 and the inward projection 21 c get over and lock. The friction body 7 can be prevented from falling out of the rear end hole.

In the present embodiment, the thermal conductivity of the friction part of the friction body 7 is set in a range of 0.05 W / (m · K) to 1.0 W / (m · K), and the friction body 7 The friction coefficient of the friction part with respect to the paper surface is set in the range of 0.2 to 1.0.

<Second Embodiment>
A second embodiment of the present invention will be described (see FIG. 2).
The present embodiment is a writing instrument 1 including a writing instrument body 2, a cap 6 that is detachable on the pen tip side of the writing instrument, and a friction body 7 that is attached to the top of the cap 6. A thermochromic ink 4 is built in the writing instrument body 2, and the thermochromic ink 4 is ejected from the pen tip 3. By contact between the pen tip 3 of the writing instrument body 2 and the paper surface, a thermochromic image or handwriting is obtained on the paper surface. By rubbing the image or handwriting formed on the paper surface with the friction body 7, the thermochromic image or handwriting can be discolored thermally.

The writing instrument body 2 includes a pen tip 3 made of a ballpoint pen tip, a pen tip holder 22 with the pen tip 3 fixed to the front end, an ink containing cylinder 23 with the pen tip holder 22 fixed to the front end, and the ink It comprises a tail plug 24 provided with a vent hole attached to the rear end opening of the storage cylinder 23, and a shaft cylinder 21 for storing the ink storage cylinder 23 therein. Housed in the ink storage cylinder 23 are a thermochromic ink 4 and a follower 5 that is disposed at the rear end of the thermochromic ink 4 and moves forward as the thermochromic ink 4 is consumed. The shaft cylinder 21 includes a front shaft 21a and a rear shaft 21b that are screwed together. The pen tip 3 protrudes from the front end hole of the shaft cylinder 21 (front shaft 21a).

A ball is rotatably held at the front end of the nib 3. A bullet 31 (coil spring) is accommodated in the nib 3, the ball is urged forward by the bullet 31, and the ball is placed on the inner surface of the inward front end edge of the nib 3. Press contact.

A nib seal member 61 made of a soft material is accommodated in the cap 6. When the cap 6 is mounted on the nib side, the nib 3 is in close contact with the nib seal member 61 and the nib 3 is sealed. The A friction body 7 made of a soft synthetic resin is attached to the attachment hole at the top of the cap 6.

In the present embodiment, the thermal conductivity of the friction part of the friction body 7 is set in a range of 0.05 W / (m · K) to 1.0 W / (m · K), and the friction body 7 The friction coefficient of the friction part with respect to the paper surface is set in the range of 0.2 to 1.0.

<Third Embodiment>
A third embodiment of the present invention will be described (see FIG. 3).
The present embodiment is a writing instrument 1 including a writing instrument body 2, a cap 6 that is detachable on the pen tip side of the writing instrument body 2, and a friction body 7 that is attached to the rear end of the writing instrument body 2. A thermochromic ink 4 is built in the writing instrument body 2, and the thermochromic ink 4 is ejected from the pen tip 3. By contact between the pen tip 3 of the writing instrument body 2 and the paper surface, a thermochromic image or handwriting is obtained on the paper surface. By rubbing the image or handwriting formed on the paper surface with the friction body 7, the thermochromic image or handwriting can be thermally discolored.

The writing instrument body 2 includes a pen tip 3 made of a fiber processed body or a porous body, an ink tank 25 in which the pen tip 3 is attached to the front end portion so as to be movable back and forth, and pressing the pen tip 3 backward. It comprises a valve device 26 that opens, a shaft cylinder 21 that holds the rear portion of the ink tank 25, and a friction body 7 made of a soft synthetic resin attached to the rear end portion of the shaft cylinder 21. A stirring member 41 is accommodated in the ink tank 25.

In the present embodiment, the thermal conductivity of the friction part of the friction body 7 is set in a range of 0.05 W / (m · K) to 1.0 W / (m · K), and the friction body 7 The friction coefficient of the friction part with respect to the paper surface is set in the range of 0.2 to 1.0.

<Fourth embodiment>
A fourth embodiment of the present invention will be described (see FIG. 4).
The present embodiment is a writing instrument 1 including a writing instrument body 2, a cap 6 that is detachable on the pen tip side of the writing instrument body 2, and a friction body 7 that is attached to the rear end of the writing instrument body 2. A thermochromic ink is accommodated in the writing instrument body 2, and the thermochromic ink is discharged from the pen tip 3. By contact between the pen tip 3 of the writing instrument body 2 and the paper surface, a thermochromic image or handwriting is obtained on the paper surface. By rubbing the image or handwriting formed on the paper surface with the friction body 7, the thermochromic image or handwriting can be thermally discolored.

The writing instrument body 2 includes a nib 3 made of a fiber processed body or a porous body, a nib holder 22 for holding the nib 3, and the nib holder 22 at the front end and an ink occlusion body 27 inside. And a friction body 7 made of a soft synthetic resin attached to the rear end portion of the shaft cylinder 21. The ink occlusion body 27 is made of a member having continuous pores (for example, a porous material such as a fiber processed body or a porous foam), and the ink occlusion body 27 is impregnated with thermochromic ink. The rear end portion of the pen tip 3 is connected to the front end portion of the ink storage body 27. The friction body 7 is attached to the outer surface of the rear end portion of the shaft cylinder 21 by fitting, or is formed integrally by two-color molding.

In the present embodiment, the thermal conductivity of the friction part of the friction body 7 is set in a range of 0.05 W / (m · K) to 1.0 W / (m · K), and the friction body 7 The friction coefficient of the friction part with respect to the paper surface is set in the range of 0.2 to 1.0.

<Fifth embodiment>
A fifth embodiment of the present invention will be described (see FIG. 5).
The present embodiment is a writing instrument 1 having a pen tip 3 at the front end of the writing instrument body 2 and a friction body 7 at the rear end of the writing instrument body 2. A thermochromic ink 4 is accommodated in the writing instrument body 2, and the thermochromic ink 4 is discharged from the pen tip 3. By contact between the pen tip 3 of the writing instrument body 2 and the paper surface, a thermochromic image or handwriting is obtained on the paper surface. By rubbing the image or handwriting formed on the paper surface with the friction body 7, the thermochromic image or handwriting can be thermally discolored.

The writing instrument body 2 includes a pen tip 3 made of a ballpoint pen tip, a pen tip holder 22 for holding the pen tip 3, an ink reservoir 28 having the pen tip holder 22 at a front end, and the ink reservoir. And an ink tank 25 for storing the thermochromic ink 4 directly inside. The ink reservoir 28 is a member that is disposed between the nib 3 and the ink tank 25, and temporarily holds the overflow ink that accompanies the pressure increase in the ink tank 25. Is adopted. The friction body 7 is made of a soft synthetic resin and is attached to the rear end hole of the ink tank 25.

In the present embodiment, the thermal conductivity of the friction part of the friction body 7 is set in the range of 0.05 W / (m · K) to 1.0 W / (m · K), and the friction body 7 The friction coefficient of the friction part with respect to the paper surface is set in the range of 0.2 to 1.0.

<Sixth Embodiment>
A sixth embodiment of the present invention will be described (see FIGS. 6 and 7).
The present embodiment is a writing instrument set including a writing instrument 1 and a friction body 7.
A thermochromic ink 4 is built in the writing instrument 1, and the thermochromic ink 4 is discharged from the pen tip 3. By contact between the pen tip 3 of the writing instrument 1 and the paper surface, a thermochromic image or handwriting is obtained on the paper surface. By rubbing the image or handwriting formed on the paper surface with the friction body 7, thermal discoloration can be achieved.

The writing instrument 1 includes a writing instrument body 2 having a nib 3 at the front end and containing a thermochromic ink 4 therein, and a cap 6 detachably attached to the nib side of the writing instrument body 2.

The writing instrument body 2 includes a pen tip 3 made of a ballpoint pen tip, a pen tip holder 22 with the pen tip 3 fixed to the front end, an ink containing cylinder 23 with the pen tip holder 22 fixed to the front end, and the ink It comprises a tail plug 24 provided with a vent hole attached to the rear end opening of the storage cylinder 23, and a shaft cylinder 21 for storing the ink storage cylinder 23 therein. Housed in the ink storage cylinder 23 are a thermochromic ink 4 and a follower 5 that is disposed at the rear end of the thermochromic ink 4 and moves forward as the thermochromic ink 4 is consumed. The shaft cylinder 21 includes a front shaft 21a and a rear shaft 21b that are screwed together. The pen tip 3 protrudes from the front end hole of the shaft cylinder 21 (front shaft 21a).

A ball is rotatably held at the front end of the nib 3. A bullet 31 (coil spring) is accommodated in the nib 3, the ball is urged forward by the bullet 31, and the ball is placed on the inner surface of the inward front end edge of the nib 3. Press contact.

A nib seal member 61 made of a soft material is accommodated in the cap 6. When the cap 6 is mounted on the nib side, the nib 3 is in close contact with the nib seal member 61 and the nib 3 is sealed. The

The friction body 7 includes outward projections 71 on the outer surface made of a soft synthetic resin. The friction body 7 is attached to the front end portion of the friction body holder 8. The friction body holder 8 has a cylindrical shape, and an inward projection 81 is formed on the inner surface of the front end portion. The inward projection 81 and the outward projection 71 get over and are locked, and the friction body 7 is prevented from falling off.

In the present embodiment, the thermal conductivity of the friction part of the friction body 7 is set in a range of 0.05 W / (m · K) to 1.0 W / (m · K), and the friction body 7 The friction coefficient of the friction part with respect to the paper surface is set in the range of 0.2 to 1.0.

It is a longitudinal cross-sectional view of the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the 3rd Embodiment of this invention. It is a longitudinal cross-sectional view of the 4th Embodiment of this invention. It is a longitudinal cross-sectional view of the 5th Embodiment of this invention. It is a longitudinal cross-sectional view of the writing instrument of the 6th Embodiment of this invention. It is a longitudinal cross-sectional view of the friction body of the 6th Embodiment of this invention. It is explanatory drawing which shows the discoloration behavior of a heat decoloring type reversible thermochromic ink.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Writing instrument 2 Writing instrument main body 21 Shaft cylinder 21a Front shaft 21b Rear shaft 21c Inward protrusion 22 Pen tip holder 23 Ink storage cylinder 24 Tail plug 25 Ink tank 26 Valve device 27 Ink storage body 28 Ink storage body 3 Pen tip 31 Bullet 4 Thermochromic ink 41 Stirring member 5 Follower 6 Cap 61 Pen tip seal member 7 Friction body 71 Outward protrusion 8 Friction body holder 81 Inward protrusion

Claims (6)

A friction body that rubs a thermochromic image or handwriting formed on a paper surface using a thermochromic ink and thermally discolors the thermochromic image or handwriting by frictional heat generated at that time,
A friction body, wherein a thermal conductivity of a friction portion of the friction body is set in a range of 0.05 W / (m · K) to 50 W / (m · K). The friction body according to claim 1, wherein the thermal conductivity of the friction portion of the friction body is set in a range of 0.05 W / (m · K) to 20 W / (m · K). The friction body according to claim 1, wherein the thermal conductivity of the friction portion of the friction body is set in a range of 0.05 W / (m · K) to 10 W / (m · K). The friction body according to any one of claims 1 to 3, wherein a friction coefficient of the friction portion of the friction body with respect to a paper surface is set in a range of 0.2 to 1.0. A writing instrument comprising the friction body according to any one of claims 1 to 4 as a part of a writing instrument having a built-in thermochromic ink and capable of discharging the thermochromic ink. A writing instrument set comprising the friction body according to any one of claims 1 to 4 and a writing instrument that contains a thermochromic ink and is capable of discharging the thermochromic ink.

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