JP2011079205A - Thermochromic writing utensil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermochromic writing utensil that can surely intercept ventilation between the inside of a shaft cylinder and the outside of the shaft cylinder in the rear end opening of the shaft cylinder mounted with a friction body. <P>SOLUTION: A thermochromic ink is stored inside the shaft cylinder 2. The front end of the shaft cylinder 2 is provided with a pen point 4 capable of ejecting the thermochromic ink. The rear end of the shaft cylinder 2 is provided with the friction body 5 rubbing against thermochromic handwriting in the thermochromic ink to thermally discolor the thermochromic handwriting with frictional heat generated at that time. The outer surface of the friction body 5 is provided with an annular outer seal part 51b, and the rear end opening inner surface of the shaft cylinder 2 is provided with an annular inner seal part 22. The outer seal part 51b and the inner seal part 22 are airtightly suitable for each other to intercept ventilation between the inside of the shaft cylinder 2 and the outside of the shaft cylinder 2 in the rear end opening of the shaft cylinder 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a thermochromic writing instrument. Specifically, thermochromic ink is accommodated inside the shaft tube, a pen tip capable of discharging the thermochromic ink is provided at the front end of the shaft tube, and the thermochromic ink is disposed at the rear end of the shaft tube. The present invention relates to a thermochromic writing instrument provided with a friction body for rubbing the thermochromic handwriting by rubbing and thermally discoloring the thermochromic handwriting by frictional heat generated at that time.

Conventionally, in this type of writing instrument, for example, Patent Document 1 describes a configuration in which a friction body for thermally discoloring a thermochromic handwriting by frictional heat is provided at the rear end of the shaft cylinder. In the above-mentioned Patent Document 1, when the writing instrument is a gel ink ballpoint pen provided with an ink backflow prevention body, ventilation between the shaft cylinder inner space behind the ink backflow prevention body and the outside of the shaft cylinder is necessary. No. 2 describes a structure that allows ventilation between the inside of the shaft tube and the outside of the shaft tube by a friction body provided with a vent hole.

JP 2008-155624 A

In the conventional thermochromic writing instrument, a friction body is attached to the rear end opening of the shaft tube, and the ventilation between the inner side of the shaft tube and the outside of the shaft tube at the rear end opening of the shaft tube can be reliably blocked. Not proposed.

An object of the present invention is to provide a thermochromic writing instrument capable of reliably blocking the ventilation between the inside of the shaft tube and the outside of the shaft tube at the rear end opening of the shaft tube to which the friction body is attached.
In the present invention, “front” refers to the pen tip side, and “rear” refers to the opposite side (friction body side).

<1> In the first invention of the present application, a thermochromic ink is accommodated in the shaft cylinder 2, and a nib 4 capable of discharging the thermochromic ink is provided at the front end of the shaft cylinder 2, and the shaft cylinder 2 is a thermochromic writing instrument provided with a friction body 5 for rubbing the thermochromic handwriting by the thermochromic ink at the rear end of the base plate 2 and rubbing the thermochromic handwriting with frictional heat generated at that time. An annular outer seal portion 51b is provided on the outer surface of the friction body 5, an annular inner seal portion 22 is provided on the inner surface of the rear end opening of the shaft cylinder 2, and the outer seal portion 51b and the inner seal portion 22 are hermetically fitted. It is a requirement to block ventilation between the inside of the shaft tube 2 and the outside of the shaft tube 2 at the rear end opening of the shaft tube 2 by combining them. (See FIGS. 1 to 8)

In the thermochromic writing instrument 1 of the first invention, an annular outer seal portion 51b is provided on the outer surface of the friction body 5, an annular inner seal portion 22 is provided on the inner surface of the rear end opening of the shaft cylinder 2, and the outer seal. By fitting the portion 51b and the inner seal portion 22 in an airtight manner, the air flow between the inside of the shaft tube 2 and the outside of the shaft tube 2 at the rear end opening of the shaft tube 2 is blocked, thereby making the friction body 5 Ventilation between the inside of the shaft tube 2 and the outside of the shaft tube 2 at the rear end opening of the attached shaft tube 2 can be reliably blocked. In the thermochromic writing instrument 1 of the first invention, the rear end opening of the shaft tube 2 is directly sealed by the friction body 5, and the inside of the shaft tube 2 and the shaft tube through the rear end opening of the shaft tube 2 are sealed. 2 Because of the configuration that blocks ventilation between the outside, an increase in the number of parts can be suppressed.

<2> A second invention of the present application is the thermochromic writing instrument 1 according to the first invention, wherein the friction body 5 includes an insertion portion 51 and a friction portion 52 formed behind the insertion portion 51. The insertion portion 51 is inserted into the rear end opening of the shaft tube 2 from the rear to the front, the friction portion 52 protrudes rearward from the rear end of the shaft tube 2, and the outer seal portion 51b is formed on the outer surface of the insertion portion 51. Is a requirement. (See FIGS. 1 to 8)

The thermochromic writing instrument 1 according to the second aspect of the present invention has a reliable airtight fit between the outer seal portion 51b on the outer surface of the insertion portion 51 and the inner seal portion 22 on the inner surface of the rear end opening of the shaft tube 2 by the above configuration. Is obtained, and the friction body 5 can be sufficiently protruded rearward from the rear end of the shaft cylinder 2.

<3> The third invention of the present application is that, in the thermochromic writing instrument 1 of the second invention, an annular inward projection 21 is formed on the inner surface of the rear end opening of the shaft tube 2, and an inner seal is formed on the inward projection 21. Part 22 is formed, an outward projection 51a is formed on the outer surface of the insertion part 51 of the friction body 5, an outer seal part 51b is formed on the outer surface of the friction body 5 behind the outward projection 51a, and the outward projection 51a It is a requirement that the inward projection 21 is overtaken and engaged. (See Figs. 1 and 2)

The thermochromic writing instrument 1 according to the third aspect of the invention can reliably block ventilation between the inside of the shaft cylinder 2 and the outside of the shaft cylinder 2 at the rear end opening of the shaft cylinder 2 to which the friction body 5 is attached.

<4> According to a fourth invention of the present application, in the thermochromic writing instrument 1 of the second invention, an inward projection 21 is formed on the inner surface of the rear end opening of the shaft tube 2, and the inner side is forward of the inward projection 21. A seal portion 22 is formed, an annular outward projection 51a is formed on the outer surface of the insertion portion 51 of the friction body 5, an outer seal portion 51b is formed on the outward projection 51a, and the outward projection 51a and the inward projection 21 are It is a requirement to be able to get over and engage. (See Figs. 3 and 4)

The thermochromic writing instrument 1 according to the fourth aspect of the present invention can reliably block ventilation between the inside of the shaft tube 2 and the outside of the shaft tube 2 at the rear end opening of the shaft tube 2 to which the friction body 5 is attached.

<5> According to a fifth aspect of the present invention, in the thermochromic writing instrument 1 of the second aspect, an inward projection 21 is formed on the inner surface of the rear end opening of the shaft tube 2, and a shaft in front of the inward projection 21 is formed. An inner seal portion 22 is formed on the inner surface of the rear end opening of the cylinder 2, an outward projection 51a is formed on the outer surface of the insertion portion 51 of the friction body 5, and an outer seal portion is formed on the outer surface of the insertion portion 51 in front of the outward projection 51a. 51b is formed, and the outward projection 51a and the inward projection 21 are required to get over and engage with each other. (See FIGS. 5 and 6)

The thermochromic writing instrument 1 according to the fifth aspect of the invention can reliably block ventilation between the inside of the shaft cylinder 2 and the outside of the shaft cylinder 2 at the rear end opening of the shaft cylinder 2 to which the friction body 5 is attached.

<6> The sixth invention of the present application is the thermochromic writing instrument 1 according to the second invention, wherein a female screw portion 23 is formed on the inner surface of the rear end opening of the shaft tube 2, and a shaft in front of the female screw portion 23 is formed. The inner seal portion 22 is formed on the inner surface of the rear end opening of the cylinder 2, the male screw portion 51c is formed on the outer surface of the insertion portion 51 of the friction body 5, and the outer seal portion is formed on the outer surface of the insertion portion 51 in front of the male screw portion 51c. 51b is formed, and the female screw portion 23 and the male screw portion 51c are screwed together. (See Figs. 7 and 8)

The thermochromic writing instrument 1 according to the sixth aspect of the invention can reliably block ventilation between the inside of the shaft cylinder 2 and the outside of the shaft cylinder 2 at the rear end opening of the shaft cylinder 2 to which the friction body 5 is attached.

The thermochromic writing instrument of the present invention can reliably block ventilation between the inside of the shaft tube and the outside of the shaft tube at the rear end opening of the shaft tube to which the friction body is attached.

It is a longitudinal cross-sectional view of the 1st Embodiment of this invention. It is a principal part enlarged view of FIG. It is a longitudinal cross-sectional view of the 2nd Embodiment of this invention. It is a principal part enlarged view of FIG. It is a longitudinal cross-sectional view of the 3rd Embodiment of this invention. It is a principal part enlarged view of FIG. It is a longitudinal cross-sectional view of the 4th Embodiment of this invention. It is a principal part enlarged view of FIG.

<First Embodiment>
A first embodiment of the present invention will be described (see FIGS. 1 and 2).

A thermochromic writing instrument 1 of the present embodiment is connected to a shaft cylinder 2, an ink occlusion body 3 accommodated in the axis cylinder 2 and containing thermochromic ink therein, and the ink occlusion body 3. The pen tip 4 is attached to the front end opening of the shaft tube 2 and the friction body 5 is attached to the rear end opening of the shaft tube 2.

Shaft cylinder The shaft cylinder 2 includes a cylindrical front shaft 2a and a cylindrical rear shaft 2b. The rear end portion of the front shaft 2a and the front end portion of the rear shaft 2b are connected by screwing or fitting. The front shaft 2a and the rear shaft 2b are obtained from a molded body of synthetic resin (for example, polypropylene). An annular inward projection 21 is integrally formed on the inner surface of the rear end opening of the shaft cylinder 2 (rear shaft 2b). The front surface of the inward projection 21 is a vertical surface, and the rear surface of the inward projection 21 is formed with a tapered surface (that is, a surface having an inner diameter that increases toward the rear). A radial top portion of the inward projection 21 constitutes an annular inner seal portion 22. A plurality of ribs 24 extending in the axial direction are integrally formed on the inner surface of the shaft cylinder 2 in front of the inward projection 21.

Ink occlusion body The ink occlusion body 3 only needs to be made of a member having continuous pores that can be impregnated with ink (that is, a porous material). Examples include a processed body, a felt resin processed body, a felt needle punch processed body, and an open-cell body of a synthetic resin. The ink occlusion body may be provided with an outer skin made of a synthetic resin film or the like on the outer peripheral surface thereof. The rear end portion of the pen tip is pierced and connected to the front surface of the ink occlusion body.

The ink occlusion body 3 is impregnated with thermochromic ink. As the thermochromic ink, a type that is decolored by heating or a type that develops color by heating is adopted. The rear end of the ink occlusion body 3 is brought into contact with the rib 24 on the inner surface of the shaft cylinder 2.

Pen nib The pen nib 4 is attached to the front end of the shaft cylinder 2 (front shaft 2a). Thermochromic ink is ejected from the nib 4. The nib 4 is made of a fiber resin processed body. In addition to this, the nib 4 may be, for example, a ball-point pen tip, a heat-bonded processed body of fiber bundles, a felt processed body, a pipe-shaped pen body, a fountain pen type plate-shaped pen body having a slit at the tip, a brush pen body, Examples thereof include a porous foam of a synthetic resin and an extruded product of a synthetic resin having an axial ink guide path.

Friction body The friction body 5 is formed of a molded body of an elastic material having a bottomed cylindrical shape. The friction body 5 includes an insertion portion 51 having a small outer diameter and a friction portion 52 having a large outer diameter provided integrally therewith at the rear thereof. An annular outward projection 51 a is integrally formed on the outer surface of the front end portion of the insertion portion 51. A tapered surface (that is, a surface whose outer diameter increases toward the rear) is formed on the front surface of the outward projection 51a, and the rear surface of the outward projection 51a is a vertical surface.

The outer peripheral surface of the insertion portion 51 behind the outward projection 51a is reduced in diameter to form an outer seal portion 51b made of an annular smooth surface. The outer diameter of the outer seal portion 51 b is slightly larger than the inner diameter of the inner seal portion 22.

The friction portion 52 protrudes rearward from the rear end of the shaft tube 2. The friction part 52 has a spherical or convex curved surface. The friction part 52 includes a flange part 52 a at the front end, and the flange part 52 a is in contact with the rear end of the shaft tube 2. The outer diameter of the friction portion 52 gradually increases toward the front, and the flange portion 52a becomes the maximum outer diameter portion. The outer diameter of the flange 52a is set larger than the inner diameter of the rear end of the shaft tube 2.

Examples of the elastic material of the friction body 5 include elastic resin materials such as SBS resin, SEBS resin, and silicone resin. The elastic material constituting the friction body 5 is made of a low-abrasion elastic resin that hardly causes wear debris (erasing debris) during friction, rather than a high-abrasion elastic resin (for example, an eraser). Is adopted. When the thermochromic handwriting by the thermochromic ink is rubbed by using the friction part 52 of the friction body 5, the thermochromic handwriting is thermally discolored by frictional heat generated at that time.

Action The insertion portion 51 of the friction body 5 is inserted into the rear end opening of the shaft tube 2 from the rear to the front. At that time, the outward projection 51a of the insertion portion 51 rides over the inward projection 21 on the inner surface of the rear end opening of the shaft tube 2 from the rear to the front, and the outward projection 51a and the inward projection 21 get over and are engaged. 5 is prevented from falling off. At the same time that the outward projection 51a and the inward projection 21 get over and engage, the outer seal portion 51b on the outer surface of the insertion portion 51 and the inner seal portion 22 of the inward projection 21 on the inner surface of the rear end opening of the shaft cylinder 2 are airtightly fitted. To do. By the airtight fitting of the outer seal portion 51b and the inner seal portion 22, the ventilation through the rear end opening of the shaft tube 2 between the shaft tube 2 inside and the shaft tube 2 outside is blocked.

<Second Embodiment>
A second embodiment of the present invention will be described (see FIGS. 3 and 4).

A thermochromic writing instrument 1 of the present embodiment is connected to a shaft cylinder 2, an ink occlusion body 3 accommodated in the axis cylinder 2 and containing thermochromic ink therein, and the ink occlusion body 3. The pen tip 4 is attached to the front end opening of the shaft tube 2 and the friction body 5 is attached to the rear end opening of the shaft tube 2.

Shaft cylinder The shaft cylinder 2 includes a cylindrical front shaft 2a and a cylindrical rear shaft 2b. The rear end portion of the front shaft 2a and the front end portion of the rear shaft 2b are connected by screwing or fitting. The front shaft 2a and the rear shaft 2b are obtained from a molded body of synthetic resin (for example, polypropylene). An annular inward projection 21 is integrally formed on the inner surface of the rear end opening of the shaft cylinder 2 (rear shaft 2b). The front surface of the inward projection 21 is a vertical surface, and the rear surface of the inward projection 21 is formed with a tapered surface (that is, a surface having an inner diameter that increases toward the rear). An inner seal portion 22 made of an annular smooth surface is formed in front of the inward projection 21 on the inner surface of the rear end opening of the shaft cylinder 2. A plurality of ribs 24 extending in the axial direction are integrally formed on the inner surface of the shaft cylinder 2 in front of the inward projection 21.

Ink occlusion body The ink occlusion body 3 only needs to be made of a member having continuous pores that can be impregnated with ink (that is, a porous material). Examples include a processed body, a felt resin processed body, a felt needle punch processed body, and an open-cell body of a synthetic resin. The ink occlusion body may be provided with an outer skin made of a synthetic resin film or the like on the outer peripheral surface thereof. The rear end portion of the pen tip is pierced and connected to the front surface of the ink occlusion body.

The ink occlusion body 3 is impregnated with thermochromic ink. As the thermochromic ink, a type that is decolored by heating or a type that develops color by heating is adopted. The rear end of the ink occlusion body 3 is brought into contact with the rib 24 on the inner surface of the shaft cylinder 2.

Pen nib The pen nib 4 is attached to the front end of the shaft cylinder 2 (front shaft 2a). Thermochromic ink is ejected from the nib 4. The nib 4 is made of a fiber resin processed body. In addition to this, the nib 4 may be, for example, a ball-point pen tip, a heat-bonded processed body of fiber bundles, a felt processed body, a pipe-shaped pen body, a fountain pen type plate-shaped pen body having a slit at the tip, a brush pen body, Examples thereof include a porous foam of a synthetic resin and an extruded product of a synthetic resin having an axial ink guide path.

Friction body The friction body 5 is formed of a molded body of an elastic material having a bottomed cylindrical shape. The friction body 5 includes an insertion portion 51 having a small outer diameter and a friction portion 52 having a large outer diameter provided integrally therewith at the rear thereof. An annular outward projection 51 a is integrally formed on the outer surface of the front end portion of the insertion portion 51. A tapered surface (that is, a surface whose outer diameter increases toward the rear) is formed on the front surface of the outward projection 51a, and the rear surface of the outward projection 51a is a vertical surface. An annular outer seal portion 51b is formed at the radial top of the outward projection 51a. The outer diameter of the outer seal portion 51 b is slightly larger than the inner diameter of the inner seal portion 22.

The outer peripheral surface of the insertion portion 51 behind the outward projection 51 a is reduced in diameter, and the outer diameter is formed slightly smaller than the inner diameter of the inward projection 21.

The friction portion 52 protrudes rearward from the rear end of the shaft tube 2. The friction part 52 has a spherical or convex curved surface. The friction part 52 includes a flange part 52 a at the front end, and the flange part 52 a is in contact with the rear end of the shaft tube 2. The outer diameter of the friction portion 52 gradually increases toward the front, and the flange portion 52a becomes the maximum outer diameter portion. The outer diameter of the flange 52a is set larger than the inner diameter of the rear end of the shaft tube 2.

Examples of the elastic material of the friction body 5 include elastic resin materials such as SBS resin, SEBS resin, and silicone resin. The elastic material constituting the friction body 5 is made of a low-abrasion elastic resin that hardly causes wear debris (erasing debris) during friction, rather than a high-abrasion elastic resin (for example, an eraser). Is adopted. When the thermochromic handwriting by the thermochromic ink is rubbed by using the friction part 52 of the friction body 5, the thermochromic handwriting is thermally discolored by frictional heat generated at that time.

Action The insertion portion 51 of the friction body 5 is inserted into the rear end opening of the shaft tube 2 from the rear to the front. At that time, the outward projection 51a of the insertion portion 51 rides over the inward projection 21 on the inner surface of the rear end opening of the shaft tube 2 from the rear to the front, and the outward projection 51a and the inward projection 21 get over and are engaged. 5 is prevented from falling off. At the same time that the outward projection 51a and the inward projection 21 get over and engage, the outer seal portion 51b of the outward projection 51a on the outer surface of the front end portion of the insertion portion 51 and the inward projection 21 on the inner surface of the rear end opening portion of the shaft tube 2 The inner seal portion 22 is airtightly fitted. By the airtight fitting of the outer seal portion 51b and the inner seal portion 22, the ventilation through the rear end opening of the shaft tube 2 between the shaft tube 2 inside and the shaft tube 2 outside is blocked.

<Third Embodiment>
A third embodiment of the present invention will be described (see FIGS. 5 and 6).

A thermochromic writing instrument 1 of the present embodiment is connected to a shaft cylinder 2, an ink occlusion body 3 accommodated in the axis cylinder 2 and containing thermochromic ink therein, and the ink occlusion body 3. The pen tip 4 is attached to the front end opening of the shaft tube 2 and the friction body 5 is attached to the rear end opening of the shaft tube 2.

Shaft cylinder The shaft cylinder 2 includes a cylindrical front shaft 2a and a cylindrical rear shaft 2b. The rear end portion of the front shaft 2a and the front end portion of the rear shaft 2b are connected by screwing or fitting. The front shaft 2a and the rear shaft 2b are obtained from a molded body of synthetic resin (for example, polypropylene). An annular inward projection 21 is integrally formed on the inner surface of the rear end opening of the shaft cylinder 2 (rear shaft 2b). An inner seal portion 22 made of an annular smooth surface is integrally formed in front of the inward projection 21 on the inner surface of the rear end opening of the shaft cylinder 2. A plurality of ribs 24 extending in the axial direction are integrally formed on the inner surface of the shaft cylinder 2 in front of the inward projection 21.

Ink occlusion body The ink occlusion body 3 only needs to be made of a member having continuous pores that can be impregnated with ink (that is, a porous material). Examples include a processed body, a felt resin processed body, a felt needle punch processed body, and an open-cell body of a synthetic resin. The ink occlusion body may be provided with an outer skin made of a synthetic resin film or the like on the outer peripheral surface thereof. The rear end portion of the pen tip is pierced and connected to the front surface of the ink occlusion body.

The ink occlusion body 3 is impregnated with thermochromic ink. As the thermochromic ink, a type that is decolored by heating or a type that develops color by heating is adopted. The rear end of the ink occlusion body 3 is brought into contact with the rib 24 on the inner surface of the shaft cylinder 2.

Pen nib The pen nib 4 is attached to the front end of the shaft cylinder 2 (front shaft 2a). Thermochromic ink is ejected from the nib 4. The nib 4 is made of a fiber resin processed body. In addition to this, the nib 4 may be, for example, a ball-point pen tip, a heat-bonded processed body of fiber bundles, a felt processed body, a pipe-shaped pen body, a fountain pen type plate-shaped pen body having a slit at the tip, a brush pen body, Examples thereof include a porous foam of a synthetic resin and an extruded product of a synthetic resin having an axial ink guide path.

Friction body The friction body 5 is formed of a molded body of an elastic material having a bottomed cylindrical shape. The friction body 5 includes an insertion portion 51 having a small outer diameter and a friction portion 52 having a large outer diameter that is integrally provided behind the insertion portion 51. An annular outward projection 51 a is integrally formed on the outer peripheral surface of the front end portion of the insertion portion 51. An outer seal portion 51b made of an annular projection is integrally formed in front of the outward projection 51a on the outer surface of the front end portion of the insertion portion 51.

The friction portion 52 protrudes rearward from the rear end of the shaft tube 2. The friction part 52 has a spherical or convex curved surface. The friction part 52 includes a flange part 52 a at the front end, and the flange part 52 a is in contact with the rear end of the shaft tube 2. The outer diameter of the friction portion 52 gradually increases toward the front, and the flange portion 52a becomes the maximum outer diameter portion. The outer diameter of the flange 52a is set larger than the inner diameter of the rear end of the shaft tube 2.

Examples of the elastic material of the friction body 5 include elastic resin materials such as SBS resin, SEBS resin, and silicone resin. The elastic material constituting the friction body 5 is made of a low-abrasion elastic resin that hardly causes wear debris (erasing debris) during friction, rather than a high-abrasion elastic resin (for example, an eraser). Is adopted. When the thermochromic handwriting by the thermochromic ink is rubbed by using the friction part 52 of the friction body 5, the thermochromic handwriting is thermally discolored by frictional heat generated at that time.

Action The insertion portion 51 of the friction body 5 is inserted into the rear end opening of the shaft tube 2 from the rear to the front. At that time, the outward projection 51a of the insertion portion 51 rides over the inward projection 21 on the inner surface of the rear end opening of the shaft tube 2 from the rear to the front, and the outward projection 51a and the inward projection 21 get over and are engaged. 5 is prevented from falling off. At the same time that the outward projection 51a and the inward projection 21 get over and engage with each other, the outer seal portion 51b on the outer surface of the insertion portion 51 and the inner seal portion 22 on the inner surface of the rear end opening of the shaft tube 2 are airtightly fitted. By the airtight fitting of the outer seal portion 51b and the inner seal portion 22, the ventilation through the rear end opening of the shaft tube 2 between the shaft tube 2 inside and the shaft tube 2 outside is blocked.

<Fourth embodiment>
A fourth embodiment of the present invention will be described (see FIGS. 7 and 8).

A thermochromic writing instrument 1 of the present embodiment is connected to a shaft cylinder 2, an ink occlusion body 3 accommodated in the axis cylinder 2 and containing thermochromic ink therein, and the ink occlusion body 3. The pen tip 4 is attached to the front end opening of the shaft tube 2 and the friction body 5 is attached to the rear end opening of the shaft tube 2.

Shaft cylinder The shaft cylinder 2 includes a cylindrical front shaft 2a and a cylindrical rear shaft 2b. The rear end portion of the front shaft 2a and the front end portion of the rear shaft 2b are connected by screwing or fitting. The front shaft 2a and the rear shaft 2b are obtained from a molded body of synthetic resin (for example, polypropylene). A female thread portion 23 is integrally formed on the inner surface of the rear end opening of the shaft cylinder 2 (rear shaft 2b). An inner seal portion 22 formed of an annular smooth surface is integrally formed in front of the internal thread portion 23 on the inner surface of the rear end opening of the shaft cylinder 2. A plurality of ribs 24 extending in the axial direction are integrally formed on the inner surface of the shaft cylinder 2 in front of the inward projection 21.

Ink occlusion body The ink occlusion body 3 only needs to be made of a member having continuous pores that can be impregnated with ink (that is, a porous material). Examples include a processed body, a felt resin processed body, a felt needle punch processed body, and an open-cell body of a synthetic resin. The ink occlusion body may be provided with an outer skin made of a synthetic resin film or the like on the outer peripheral surface thereof. The rear end portion of the pen tip is pierced and connected to the front surface of the ink occlusion body.

The ink occlusion body 3 is impregnated with thermochromic ink. As the thermochromic ink, a type that is decolored by heating or a type that develops color by heating is adopted. The rear end of the ink occlusion body 3 is brought into contact with the rib 24 on the inner surface of the shaft cylinder 2.

Pen nib The pen nib 4 is attached to the front end of the shaft cylinder 2 (front shaft 2a). Thermochromic ink is ejected from the nib 4. The nib 4 is made of a fiber resin processed body. In addition to this, the nib 4 may be, for example, a ball-point pen tip, a heat-bonded processed body of fiber bundles, a felt processed body, a pipe-shaped pen body, a fountain pen type plate-shaped pen body having a slit at the tip, a brush pen body, Examples thereof include a porous foam of a synthetic resin and an extruded product of a synthetic resin having an axial ink guide path.

Friction body The friction body 5 is formed of a molded body of an elastic material having a bottomed cylindrical shape. The friction body 5 includes an insertion portion 51 having a small outer diameter and a friction portion 52 having a large outer diameter that is integrally provided behind the insertion portion 51. An outer seal portion 51b made of an annular protrusion is integrally formed on the outer peripheral surface of the front end portion of the insertion portion 51. A male screw part 51c is integrally formed behind the outer seal part 51b on the outer peripheral surface of the insertion part 51.

The friction portion 52 protrudes rearward from the rear end of the shaft tube 2. The friction part 52 has a spherical or convex curved surface. The friction part 52 includes a flange part 52 a at the front end, and the flange part 52 a is in contact with the rear end of the shaft tube 2. The outer diameter of the friction portion 52 gradually increases toward the front, and the flange portion 52a becomes the maximum outer diameter portion. The outer diameter of the flange 52a is set larger than the inner diameter of the rear end of the shaft tube 2.

Examples of the elastic material of the friction body 5 include elastic resin materials such as SBS resin, SEBS resin, and silicone resin. The elastic material constituting the friction body 5 is made of a low-abrasion elastic resin that hardly causes wear debris (erasing debris) during friction, rather than a high-abrasion elastic resin (for example, an eraser). Is adopted. When the thermochromic handwriting by the thermochromic ink is rubbed by using the friction part 52 of the friction body 5, the thermochromic handwriting is thermally discolored by frictional heat generated at that time.

Action The insertion portion 51 of the friction body 5 is inserted into the rear end opening of the shaft tube 2 from the rear to the front. At that time, the male screw portion 51 c of the insertion portion 51 is screwed with the female screw portion 23 on the inner surface of the rear end opening of the shaft cylinder 2, thereby preventing the friction body 5 from falling off. At the same time as the screwing of the male screw portion 51c and the female screw portion 23 is completed, the outer seal portion 51b on the outer surface of the insertion portion 51 and the inner seal portion 22 on the inner surface of the rear end opening of the shaft tube 2 are airtightly fitted. By the airtight fitting of the outer seal portion 51b and the inner seal portion 22, the ventilation through the rear end opening of the shaft tube 2 between the shaft tube 2 inside and the shaft tube 2 outside is blocked.

DESCRIPTION OF SYMBOLS 1 Thermochromic writing instrument 2 Shaft cylinder 2a Front shaft 2b Rear shaft 21 Inward protrusion 22 Inner seal part 23 Female thread part 24 Rib 3 Ink occlusion body 4 Pen tip 5 Friction body 51 Insertion part 51a Outward protrusion 51b Outer seal part 51c Male thread part 52 Friction part 52a collar part

Claims (6)

A thermochromic ink is accommodated inside the shaft tube, a pen tip capable of discharging the thermochromic ink is provided at the front end of the shaft tube, and the thermochromic property by the thermochromic ink is provided at the rear end of the shaft tube. A thermochromic writing instrument provided with a friction body for rubbing the handwriting of the ink and frictional heat generated at that time to discolor the thermochromic handwriting, provided with an annular outer seal on the outer surface of the friction body, By providing an annular inner seal portion on the inner surface of the rear end opening and airtightly fitting the outer seal portion and the inner seal portion, Thermochromic writing instrument characterized by blocking ventilation between the two. The friction body includes an insertion portion and a friction portion formed at the rear of the insertion portion. The insertion portion is inserted into the rear end opening of the shaft tube from the rear to the front, and the friction portion is disposed at the rear of the shaft tube. The thermochromic writing instrument according to claim 1, wherein the thermochromic writing instrument protrudes rearward from an end and has an outer seal portion formed on an outer surface of the insertion portion. An annular inward projection is formed on the inner surface of the rear end opening of the shaft cylinder, an inner seal portion is formed on the inward projection, an outward projection is formed on the outer surface of the insertion portion of the friction body, and a rear friction is formed with respect to the outward projection. The thermochromic writing instrument according to claim 2, wherein an outer seal portion is formed on an outer surface of the body, and the outward projection and the inward projection are overcome and engaged. An inward projection is formed on the inner surface of the rear end opening of the shaft tube, an inner seal portion is formed in front of the inward projection, an annular outward projection is formed on the outer surface of the insertion portion of the friction body, and an outer side is formed on the outward projection. The thermochromic writing instrument according to claim 2, wherein a seal portion is formed, and the outward projection and the inward projection are overcome and engaged. An inward protrusion is formed on the inner surface of the rear end opening of the shaft cylinder, an inner seal portion is formed on the inner surface of the rear end opening of the shaft cylinder in front of the inward protrusion, and an outward protrusion is formed on the outer surface of the insertion portion of the friction body. The thermochromic writing instrument according to claim 2, wherein an outer seal portion is formed on an outer surface of the insertion portion in front of the outward projection, and the outward projection and the inward projection are overcome and engaged. A female thread is formed on the inner surface of the rear end opening of the shaft cylinder, an inner seal is formed on the inner surface of the rear end opening of the shaft cylinder ahead of the female thread, and a male thread is formed on the outer surface of the insertion part of the friction body. The thermochromic writing instrument according to claim 2, wherein an outer seal portion is formed on the outer surface of the insertion portion in front of the male screw portion, and the female screw portion and the male screw portion are screwed together.

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