JP2024099835A - Thermochromic writing implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermochromic writing implement capable of easily removing a cover member that covers a friction member.

SOLUTION: There is provided a thermochromic writing implement in which a friction member 60 capable of discoloring handwriting is provided at a rear end of a rear tube 21 of a barrel, and a cover member 11 for covering and protecting the friction member is attached to an end of the barrel, and at least one protrusion and an inclined surface are provided on an inner peripheral surface of the cover member, and on an outer peripheral surface of a mounting portion 21B of the cover member at the end of the barrel, fitting portions 21C corresponding to the number of protrusions and inclined portions 21D that can abut against the inclined surface are formed, and the inclined surface is formed in a diameter-reduction direction from a front side to a rear side, and in a fitted state in which the protrusion of the cover member and the fitting portion of the barrel are passed over each other, the cover member and the barrel are rotated relative to each other, to thereby move the inclined surface along the inclined portion, allowing the cover member and the barrel to be removed.

SELECTED DRAWING: Figure 12

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a thermochromic writing instrument.

Conventionally, thermochromic writing instruments have been provided in which refills are stored inside a barrel, and the tip of one of the refills is advanced from the tip of the barrel by a specified advancement operation (see Patent Documents 1 and 2). The thermochromic writing instruments disclosed in Patent Documents 1 and 2 have an erasing member at the rear of the barrel that discolors or erases handwriting through frictional heat, and a cap or cover member is provided at the rear end of the barrel to prevent the erasing member from becoming dirty.

Patent Publication No. 2016-97664 Patent Publication 2016-144933

However, in Patent Document 1, the cap cannot be removed from the barrel unless it is rotated in the radial direction and then pulled out in the axial direction. In Patent Document 2, the cover member can be removed from the barrel by pulling it out only in the axial direction, but depending on the dimensions of the parts, there is a risk that removal will be difficult if the fitting force is too strong. Therefore, we provide a thermochromic writing instrument that allows the cover member that covers the friction member that discolors the writing of the thermochromic writing instrument with frictional heat to be easily removed.

After extensive development, the inventors have come up with the following invention: A thermochromic writing instrument, characterized in that the end of the barrel is provided with a friction member capable of discoloring handwriting written on paper, a cover member is attached to the end of the barrel to cover and protect the friction member, at least one protrusion and an inclined surface are provided on the inner peripheral surface of the cover member, and the outer peripheral surface of the mounting portion of the cover member at the end of the barrel is formed with fitting portions corresponding to the number of protrusions and an inclined portion that can come into contact with the inclined surface.

The inclined surface is formed in a direction that reduces in diameter from the front side to the rear side, and when the protrusion of the cover member and the fitting portion of the barrel are in an engaged state where they have passed over each other, the inclined surface moves along the inclined portion by rotating the cover member and the barrel relative to each other, allowing the cover member and the barrel to be removed.

It is also characterized by the fact that two or more rib-shaped protrusions are formed in the axial direction on the outer peripheral surface of the cover member.

Furthermore, the force required to remove the cover member from the barrel is smaller in the rotational direction than in the axial direction, and the force required to remove the cover member in the rotational direction is less than 0.02 N·m.

The device further comprises a front tube forming the axial tip side, a rear tube forming the axial rear end side and separable from the front tube, a barrel having a plurality of sliding grooves formed in the rear tube along the axial direction, a number of refills equal to the number of sliding grooves housed inside the barrel, knock rods connected to the rear ends of the plurality of refills and movable along the sliding grooves, a sliding protrusion protruding from the inner surface of the knock rod toward the axial center of the barrel, a knock spring that biases the knock rod toward the axial rear end, and a knock spring that is disposed at the axial center of the barrel and guides the movement of the knock rod. The cam groove has a groove formed on a surface of the rotor that rotates in a circumferential direction in association with the movement of the knock rods, the groove having a groove width allowing the sliding projection to move, and one of both side edges of the cam groove has a tip inclined edge that is inclined toward the other side edge of the cam groove and toward the tip side in the axial direction, and the other side edge has a locking edge that is located toward the rear end side in the axial direction relative to the tip inclined edge, extends toward the one side edge, and locks the sliding projection, and the cam groove has a locking edge that locks the sliding projection, and the sliding projection is locked to the locking edge. A release portion is provided from the locking position toward the one side edge and toward the tip end side of the tip inclined edge in the axial direction, and the release portion includes a first extension edge that is continuous with the tip inclined edge and extends toward the tip end side in the axial direction, a guide edge that is continuous with the first extension edge and extends toward the one side edge, a second extension edge that is continuous with the locking edge and extends so as to face the first extension edge, and a release inclined edge that is continuous with the second extension edge and inclined toward the one side edge and the tip end side in the axial direction, and one sliding protrusion is located at the locking position and the other sliding protrusion is located at the rear end of the cam groove. When the front barrel is in a standby position located on the side of the rear barrel, a rear end inclined edge is provided that is inclined toward the one side edge and the tip end in the axial direction with which the other sliding protrusion comes into contact when the other sliding protrusion is moved toward the tip end in the axial direction, and the rear end side of the guide edge is inclined toward the other side edge side, and the urging force of the knock spring guides the movement of the sliding protrusion toward the other side edge side and the rear end side in the axial direction, thereby achieving the effect of being able to release the locked state when all the knock rods are knocked and locked inside the rear barrel with the front barrel removed from the rear barrel.

When removing the cover member from the barrel, the present invention allows the cover member and barrel to be rotated relative to one another, so that the inclined surface inside the cover member rides up the inclined portion on the outer surface of the barrel, making it easy to remove with little force. This makes it particularly easy for people of all ages and genders, who generally have little strength, to remove the cover member.

1A is a front view, (B) a right side view, (C) a rear view, (D) a bottom view, and (E) a plan view of a thermochromic writing instrument according to an embodiment of the present invention. This is a cross-sectional view taken along line II-II in FIG. The outer cylinder pressing portion of the knock rod is shown in (A) a perspective view, (B) a front view, (C) a right side view, (D) a rear view, (E) a bottom view, (F) a plan view, and (G) a cross-sectional view taken along the line III-III in (E). The inner cylinder pressing portion of the knock bar is shown in (A) a perspective view, (B) a front view, (C) a right side view, (D) a rear view, (E) a bottom view, (F) a plan view, and (G) a sectional view taken along the line IV-IV in (E). The state in which the outer cylinder pressing portion and the inner cylinder pressing portion of the knock rod are combined is shown in (A) a perspective view, (B) a front view, (C) a right side view, (D) a rear view, (E) a bottom view, (F) a plan view, and (G) a VV sectional view of (E). The rotor is shown in (A) a front view, (B) a right side view, (C) a rear view, (D) a bottom view, (E) a plan view, and (F) a cross-sectional view taken along the line VI-VI in (D). FIG. 13 is a diagram showing the cam operation in the rotor. FIG. 13 is a diagram showing the cam operation in the rotor. 3A shows a state in which the front tube has been removed from the rear tube, FIG. 3B shows a fully extended state, and FIG. 3C shows a state in which the fully extended state has been released, all viewed from the same perspective as the cross-sectional view shown in FIG. FIG. 13 is a diagram showing the cam operation in the rotor. FIG. 13 is a diagram showing the cam operation in the rotor. 13 is a rear perspective view showing the state in which the cover member has been removed from the barrel. FIG. FIG. 1 shows part diagrams of the cover member, with (A) a front perspective view, (B) a left side view, (C) a plan view, (D) a front view, (E) a vertical cross-sectional view of (D), (F) a rear perspective view, and (G) a right side view.

This embodiment will be described with reference to the drawings. In the following description, the "tip side" refers to one side of the axial direction of the thermochromic writing instrument 10 that faces the front tube 22, which will be described later, and the "rear end side" refers to the other side that faces the rear tube 21, which will be described later. The direction toward the tip side is referred to as "forward," and the opposite direction is referred to as "rear." Forward movement is referred to as "forward," and rearward movement is referred to as "rearward."

In addition, "discoloration" in the present invention includes "erasing" using the above-mentioned thermochromic ink, and also refers to adsorbing or scraping off written lines, letters, etc. with an erasing part such as an eraser. Therefore, the present invention is applicable to any writing instrument that erases written lines using a friction member.

Fig. 1 shows the appearance of a thermochromic writing instrument 10 according to the present embodiment (Figs. 1(A) to (E)). Fig. 2 shows a cross-sectional view of the thermochromic writing instrument 10 according to the present embodiment taken along line II-II in Fig. 1(D).
1(A) to 1(C) and 2 show the thermochromic writing instrument 10 in a horizontal position, but the "front", "right side", "back", "bottom" and "flat surface" are based on the positional relationship of the thermochromic writing instrument 10 in a vertical position. This positional relationship is the same below.

The thermochromic writing instrument 10 of this embodiment accommodates three mechanical pencil refills 40 (see FIG. 2) inside the barrel 20. Note that in FIG. 2, only two mechanical pencil refills 40 are shown: the mechanical pencil refill 40 located on the front side and shown in cross section, and the mechanical pencil refill 40 located on the left side of that; however, there is also a mechanical pencil refill 40 located on the right side, not shown.

For the thermochromic writing instrument 10, the state in which the writing tip of the mechanical pencil refill 40 is inside the barrel 20 is referred to as the "retracted state," and for the thermochromic writing instrument 10, the state in which the writing tip of the mechanical pencil refill 40 protrudes from the barrel 20 and is ready for writing is referred to as the "protruding state."

The barrel 20 that constitutes the outermost part of the thermochromic writing instrument 10 of this embodiment is composed of a front barrel 22 that constitutes the axial tip side, a rear barrel 21 that constitutes the axial rear end side and is separable from the front barrel 22, and a middle barrel 23 (see Figure 2) that connects the rear barrel 21 and the front barrel 22.

The rear tube 21 has sliding grooves 21A formed along the axial direction that correspond to each of the three mechanical pencil refills 40. A roughly bell-shaped cover member 11 is attached to the rear end of the rear tube 21. The tip edge of this cover member 11 forms a knock button locking edge 11A (see FIG. 2) against which the rear end of the knock button 51, which is part of the knock bar 50, abuts. Meanwhile, the tip portion of the front tube 22 tapers in diameter, and at its very end is provided a tip opening 22A (see FIG. 2) through which the tip of the mechanical pencil refill 40 can protrude.

The middle tube 23 is composed of a roughly cylindrical guide section 23A that is inserted into the rear tube 21 and guides the movement of each mechanical pencil refill 40, a rear connection section 23D located in front of it and pressed against the inside surface of the rear tube 21, a front connection section 23E located further in front of it and screwed into the inside surface of the front tube 22, and an intermediate flange section 23F that defines the boundary between the rear connection section 23D and the front connection section 23E and is visible from the outside.

In addition, a support protrusion 23G is formed at the rear end of the middle cylinder 23 to support the rotor 30, which will be described later. A support hole 32 is formed at the tip of the rotor 30, into which the support protrusion 23G fits loosely.

The guide portion 23A of the middle cylinder 23 is formed with a guide hole 23B through which each mechanical pencil refill 40 is movably inserted. The rear end edge of this guide hole 23B is a knock spring tip locking edge 23C. A knock spring (not shown) is inserted around the rear end of the mechanical pencil refill 40 between this knock spring tip locking edge 23C and a knock spring rear end locking edge 52H, which is a part of the knock bar 50. The knock spring (not shown) constantly biases the knock bar 50 backward with respect to the middle cylinder 23.

The mechanical pencil refill 40 has a cylindrical lead case 41 that houses a writing lead 70 with an outer diameter of 0.3 to 1.0 mm. This lead case 41 has a double structure consisting of an inner tube 41A that directly houses the writing lead 70, and an outer tube 41B that houses the inner tube 41A. The inner tube 41A and the outer tube 41B are made of transparent or semi-transparent resin that allows the inside to be seen, and examples of the material used are polypropylene and polyethylene. At least two of the hues written on the paper surface with the writing leads 70 housed in each mechanical pencil refill 40 are red and orange, and the red is approximately close to the light with a wavelength of 620 nm or more and less than 750 nm, and the orange is approximately close to the light with a wavelength of 590 nm or more and less than 620 nm, so that the way in which the written characters are hidden by the red film sheet can be adjusted.

A lead gripping mechanism 46 that grips the writing lead 70 is connected to the tip of the inner tube 41A. The lead gripping mechanism 46 is equipped with a pressure piece 46A, the rear end of which is directly pressed into the tip of the inner tube 41A, a chuck 46C that is fixed to the tip of this pressure piece 46A and is directly involved in feeding out the writing lead 70, and a short cylindrical fastener 46E that is fitted onto the outer periphery of the tip of this chuck 46C.

The front part of the part where the pressing piece 46A is pressed into the inner tube 41A is the flange-shaped enlarged diameter chuck spring rear end locking edge 46F, and the tip of the inner tube 41A abuts against the rear end surface of this chuck spring rear end locking edge 46F.

The chuck 46C is made of a metal such as brass, and its tip portion is an expansion portion 46D that expands in diameter in a roughly bell-like shape. This expansion portion 46D is divided into multiple radial portions and is plastically deformed so that it expands radially outward. A fastener 46E is inserted into the expansion portion 46D, tightening it and preventing it from expanding.

A covering tube 43 that covers the core gripping mechanism 46 except for the expansion section 46D is connected to the tip of the outer tube 41B via a joint 42. The inner diameter of the covering tube 43 is reduced at approximately the middle portion to form a step, which serves as the chuck spring tip locking edge 43A.

Between the chuck spring tip locking edge 43A and the chuck spring rear end locking edge 46F, a chuck spring 46B is interposed, which constantly urges the inner tube 41A backward. Furthermore, a generally cylindrical tip member 44, which tapers in stages forward, is connected to the tip of the covering tube 43.

A tip step 44A with a reduced inner diameter is formed in a position approximately in the middle of the tip member 44, slightly forward of the expansion section 46D of the chuck 46C. The space in front of this tip step 44A is an expansion chamber 44B that can be expanded by moving the chuck 46C forward.

The tip member 44 tapers in a stepwise manner further forward of the tip step 44A, and the tip of the tip tapers to an inner diameter that allows the writing lead 70 to pass through. A protective member 45 made of soft resin is attached to the inside of the rear end of the tip to protect the writing lead 70.

The knock rod 50 is composed of a knock button 51 that protrudes outward from the sliding groove 21A of the rear barrel 21, an outer barrel pressing part 52 that presses the outer barrel 41B, and an inner barrel pressing part 53 that presses the inner barrel 41A. The knock rod 50 is connected to the rear end of each of the mechanical pencil refills 40 and is movable along the sliding groove 21A.

In one of the three knock rods 50, the knock button 51 is integrally formed with the clip 51A. In FIG. 2, a cross section of the sliding protrusion 52E protruding from the outer cylinder pressing portion 52 toward the shaft center is visible. The other knock rods 50 will be described in detail later.

The rotor 30 is attached to the rear end portion of the interior of the rear cylinder 21, at the axis of the shaft cylinder 20. The rotor 30 is a substantially cylindrical member, and at its tip, as described above, a support hole 32 is formed into which the support protrusion 23G is loosely fitted. Cam grooves 31 corresponding to each knock rod 50 are formed on the surface of the rotor 30. The rotor 30 guides the movement of the knock rod 50 by the cam grooves 31, and rotates in the circumferential direction in response to the movement of the knock rod 50. This will be described in detail later.

Figure 3 shows the outer cylinder pressing portion 52 of the knock rod 50 in (A) a perspective view, (B) a front view, (C) a right side view, (D) a rear view, (E) a bottom view, (F) a plan view, and (G) a cross-sectional view taken along line III-III of (E).

The outer tube pressing part 52 has a sliding part 52A that slides along the cam groove 31, a press-fit part 52B that is press-fitted into the outer tube 41B, and a connecting part 52C that connects the sliding part 52A and the press-fit part 52B. The outer tube pressing part 52 is connected to the rear end of the outer tube 41B by this press-fit part 52B.

The sliding portion 52A and the connecting portion 52C are continuous and seamless, and have a long plate shape that is curved in an arc along the circumferential direction (see FIG. 3(F)). Wing-shaped protrusions 52F are formed on both sides of the sliding portion 52A, protruding laterally.

This wing-like projection 52F plays the role of supporting the side of the knock button 51 that contacts the outer surface of the outer cylinder pressing portion 52 when connected to the inner cylinder pressing portion 53. In addition, on the inner surface side of the sliding portion 52A, a sliding projection 52E that directly contacts the cam groove 31 protrudes toward the shaft center (see Figures 3 (D), (F) and (G)).

Between the connecting portion 52C and the press-fit portion 52B, a flange portion 52D is formed that protrudes outward in an annular shape. The surface on the tip side of this flange portion 52D forms the rear end locking edge 52H of the knock spring described above.

A notch 52G is formed on the front side from the flange portion 52D to the press-fit portion 52B, through which the inner cylinder pressing portion 53 is inserted. The outer surface side of the tip portion of the notch 52G forms an outwardly inclined surface 52I that is inclined so that the thickness decreases toward the front (see Figures 3 (A), (B), (E), and (G)).

Figure 4 shows the inner cylinder pressing portion 53 of the knock bar 50 in (A) a perspective view, (B) a front view, (C) a right side view, (D) a rear view, (E) a bottom view, (F) a plan view, and (G) a cross-sectional view taken along line IV-IV of (E).

The inner cylinder pressing portion 53 has a pair of protruding connection portions 53A involved in the connection with the knock button 51, an insertion portion 53B that is inserted into the notch portion 52G, and an abutment portion 53C formed at the tip of the insertion portion 53B and having a flat tip. The inner cylinder pressing portion 53 is connected to the knock button 51 by recessing the connection protrusions 51B (see Figure 2) of the knock button 51 between the connection portions 53A.

The press-fit portion 52B is narrower than the connection portion 53A, and the step forms a shoulder 53E. The tip side of the connection portion 53A forms a protruding portion 53D that protrudes outward.

The insertion portion 53B advances with the knocking action and slides along the insertion portion 53B. The abutment portion 53C abuts against the rear end of the inner tube 41A as the insertion portion 53B advances with the knocking action. The inner surface of the tip portion of the insertion portion 53B forms an inwardly inclined surface 53F that is inclined so as to increase in thickness toward the abutment portion 53C (see Figures 4 (C), (D), and (G)).

Figure 5 shows the state in which the outer cylinder pressing portion 52 and the inner cylinder pressing portion 53 are combined, in (A) a perspective view, (B) a front view, (C) a right side view, (D) a rear view, (E) a bottom view, (F) a plan view, and (G) a V-V cross-sectional view of (E).

Figure 5 shows the state in which the knock rod 50 is in the rearmost position, i.e., the position shown in Figure 2. In this state, the inwardly inclined surface 53F of the inner cylinder pressing portion 53 is in contact with the outwardly inclined surface 52I of the outer cylinder pressing portion 52 (see Figure 5 (G)). From this state, the insertion portion 53B inserted into the notch portion 52G advances due to the knocking action, and as a result, the inwardly inclined surface 53F moves away from the outwardly inclined surface 52I. As a result, the shoulder portion 53E of the inner cylinder pressing portion 53 approaches the flange portion 52D.

Figure 6 shows the rotor 30 in (A) a front view, (B) a right side view, (C) a rear view, (D) a bottom view, (E) a plan view, and (F) a cross-sectional view taken along line VI-VI of (D).

For the convenience of molding, the rotor 30 is molded separately into a front member 33 located at the front and a rear member 34 located at the rear. The rotor 30 is formed by combining the front member 33 and the rear member 34, and has an approximately cylindrical shape as a whole. The aforementioned support hole 32 is formed in the tip surface of the rotor 30. In addition, three cam grooves 31, the same number as the knock rods 50, are formed in the surface of the rotor 30.

The cam groove 31 has a groove width that allows the sliding protrusion 52E to move, and is referred to, from its rear end, as a rear end portion 31A, a central portion 31B, a tip portion 31C, and a release portion 31D. In addition, the left side of the cam groove 31 in the drawing is referred to as a left edge 31L, and the right side is referred to as a right edge 31R.

The rear end 31A is a relatively wide portion of the cam groove 31, and its right edge 31R is provided with a rear end inclined edge 31E that is inclined toward the left edge 31L and forward. This rear end inclined edge 31E is the portion that the other sliding protrusion 52E contacts when the other sliding protrusion 52E is advanced when one sliding protrusion 52E is in an engagement position described below and the other sliding protrusion 52E is in a standby position located at the rear end 31A. The tip of the rear end inclined edge 31E reaches the center portion 31B.

The central portion 31B is a portion of the cam groove 31 with a relatively narrow groove width, and the left edge 31L and right edge 31R extending along the axial direction face each other. The right edge 31R extending along the axial direction in the central portion 31B bends to the right (later-described locking edge 31G) and reaches the tip portion 31C.

The tip portion 31C is a relatively wide portion of the cam groove 31, and its left edge 31L is provided with a tip inclined edge 31F that is inclined toward the right edge 31R and forward. In addition, the right edge 31R of the tip portion 31C is provided with a locking edge 31G that extends from the tip of the right edge 31R in the central portion 31B, bending to the right at an acute angle slightly less than 90°. This locking edge 31G is used when positioning the sliding protrusion 52E at an engagement position where the sliding protrusion 52E is locked to the locking edge 31G. The tip of the tip inclined edge 31F leads to the release portion 31D.

The release portion 31D is a portion of the cam groove 31 that allows the sliding protrusion 52E, which is in the engagement position, to move forward of the leading inclined edge 31F and toward the left edge 31L from the engagement position. This release portion 31D is composed of a first extension edge 31H, a guide edge 31I, a second extension edge 31J, and a release inclined edge 31K.

The first extension edge 31H is a portion provided on the left edge 31L of the release portion 31D, and extends forward along the axial direction, continuing from the tip inclined edge 31F.

The guiding edge 31I is a portion provided on the left edge 31L of the release portion 31D, and extends toward the left edge 31L in continuation with the first extension edge 31H. The rear end side of the guiding edge 31I is inclined toward the right edge 31R.

The second extension edge 31J is a portion provided on the right edge 31R of the release portion 31D, and extends axially so as to be continuous with the locking edge 31G and face the first extension edge 31H.

The release inclined edge 31K is a portion provided on the right edge 31R of the release portion 31D, and is inclined toward the left edge 31L and forward, continuing from the second extension edge 31J. The release inclined edge 31K and the induction edge 31I face each other.

The tip of the release section 31D, i.e., the tip of the cam groove 31, is provided with a narrow tip section 31M that is slightly narrower than the width of the sliding protrusion 52E. When the sliding protrusion 52E advances along the release section 31D and reaches the narrow tip section 31M, the knock button 51 comes into contact with the tip of the sliding groove 21A, stopping its advance.

The knocking action of the thermochromic writing instrument 10 of this embodiment will be described below with reference to Figures 2 and 7 to 11. Note that in Figures 7 and 8, 10 and 11, the position of the sliding protrusion 52E in the cam groove 31 is indicated by the hatched area.

In the following description, the thermochromic writing instrument 10 is in the retracted state (see FIG. 2). At this time, the sliding protrusions 52E of all the knock bars 50 are in contact with the left edge 31L at the rear end 31A of the cam groove 31 and are in the standby position (see FIG. 7A).

When one knock button 51 is advanced from this standby position, the inner cylinder pressing portion 53 connected to the one knock button 51 advances and comes into contact with the rear end of the inner cylinder 41A.

At this time, the pressure piece 46A connected to the tip of the inner tube 41A presses the covering tube 43 forward via the chuck spring 46B. This forward pressure is also transmitted to the outer tube 41B connected via the joint 42, resulting in the entire mechanical pencil refill 40 moving forward while compressing the knock spring (not shown).

At this time, the outer tube pressing portion 52 connected to the outer tube 41B also advances at the same time, so that the sliding protrusion 52E advances along the left edge 31L of the cam groove 31 and through the center portion 31B (see FIG. 7B).

When one knock button 51 is advanced further from the state where it has passed through the central portion 31B, the sliding protrusion 52E reaches the tip inclined edge 31F (see FIG. 7(C)). Here, the force generated by the advancement of the sliding protrusion 52E presses the tip inclined edge 31F to the left, and the reaction acts to apply a force to the right on the sliding protrusion 52E. However, the knock button 51, which is located outside the sliding portion 52A to which the sliding protrusion 52E belongs, cannot move left or right because it moves along the sliding groove 21A of the barrel tube 20 (rear tube 21).

Furthermore, one knock button 51 is pressed down on both the left and right sides by wing-shaped protrusions 52F (see FIG. 3) on both sides of the sliding portion 52A, so that the sliding protrusion 52E cannot move to the right. Therefore, the leftward pressure on the leading inclined edge 31F causes the rotor 30 to rotate clockwise (the direction of rotation as seen from the rear end; the same applies below).

When the first knock button 51 is moved forward from a state in which the rotor 30 has rotated clockwise, the sliding protrusion 52E moves forward through the release section 31D and reaches the release inclined edge 31K. Here, the force generated by the forward movement of the sliding protrusion 52E presses the release inclined edge 31K to the right, and as a reaction to this, a force is applied to the left on the sliding protrusion 52E. However, as described above, the sliding protrusion 52E cannot move to the left, so the rightward pressing force on the release inclined edge 31K causes the rotor 30 to rotate counterclockwise.

When the first knock button 51 is moved forward from the state in which the rotor 30 has rotated counterclockwise, the sliding protrusion 52E reaches the narrow tip portion 31M (see FIG. 7(D)), and the knock button 51 comes into contact with the tip of the sliding groove 21A, stopping the forward movement of the sliding protrusion 52E. At this time, the thermochromic writing instrument 10 is in a state in which the mechanical pencil refill 40 protrudes most from the tip opening 22A of the tip tube 22.

When pressure on one knock button 51 is released from the state in which the mechanical pencil refill 40 protrudes most from the tip opening 22A, the entire mechanical pencil refill 40 is pushed back backward by the restoring force of the knock spring (not shown). Thereafter, the mechanical pencil refill 40 stops moving backward when the sliding protrusion 52E abuts against the locking edge 31G (see FIG. 7(E)). In other words, the sliding protrusion 52E is in the locking position.

Therefore, when the sliding protrusion 52E is in the locked position, the thermochromic writing instrument 10 maintains the writing tip of the mechanical pencil refill 40 in a protruding state at a position slightly retracted from the maximum protruding state from the tip opening 22A.

When the knock button 51 with the sliding protrusion 52E in the locking position is advanced, the sliding protrusion 52E moves until it reaches the narrow tip portion 31M (see FIG. 7(D)). At this time, the inner tube 41A, which is pressed forward by the abutting portion 53C of the inner tube pressing portion 53, advances, and the chuck 46C is pressed forward while compressing the chuck spring 46B via the pressing piece 46A.

Then, the expanding portion 46D of the chuck 46C advances toward the forward expanding chamber 44B, and expands without being restrained by the fastener 46E, and the writing lead 70 is advanced forward.

In other words, the distance that the sliding protrusion 52E can move in the cam groove 31 from the engaging edge 31G to the narrow tip portion 31M (in other words, the distance from the rear end of the sliding protrusion 52E to the engaging edge 31G in FIG. 7(D), or the distance from the tip of the sliding protrusion 52E to the narrow tip portion 31M in FIG. 7(E)) is one knock stroke in advancing the writing lead 70, and the knocking action causes the sliding protrusion 52E to move back and forth over this distance.

When the sliding protrusion 52E reaches the narrow tip portion 31M and the knock button 51 is in contact with the tip of the sliding groove 21A, the pressure on one knock button 51 is released, and the restoring force of the knock spring (not shown) causes the sliding protrusion 52E to move toward the right edge 31R and rearward along the guiding edge 31I, and when it comes into contact with the locking edge 31G (see FIG. 7(E)), its retreat stops. In other words, the sliding protrusion 52E is in the locking position. At the same time, the chuck 46C also retreats, and the widening portion 46D is again restrained by the fastener 46E.

At this time, when writing pressure is applied to the writing lead 70, the mechanical pencil refill 40 has room to retreat to a position where the abutment portion 53C of the inner cylinder pressing portion 53 abuts against the tip of the press-in portion 52B of the outer cylinder pressing portion 52. During this retreat, the expansion portion 46D of the chuck 46C wedges into the fastener 46E, so that the writing pressure is transferred to the lead holding force of the chuck 46C.

As a result, there is no longer a need for the chuck spring 46B alone to bear the core retention force, and the load of the chuck spring 46B is sufficient to secure the fastener 46E to the chuck 46C (specifically, approximately 2N).

When one sliding protrusion 52E is in the locked position, the other sliding protrusion 52E is in a position where the rotor 30 has rotated clockwise relative to the original position (i.e., the position shown in FIG. 7A), so that the rear end 31A of the cam groove 31 contacts the rear end inclined edge 31E of the right edge 31R (see FIG. 8A).

When one sliding protrusion 52E is in the locking position, if the knock button 51 having the other sliding protrusion 52E is advanced, the other sliding protrusion 52E presses against the rear end inclined edge 31E.

Here, the force generated by the forward movement of the sliding protrusion 52E presses the rear end inclined edge 31E to the right, and the reaction acts on the sliding protrusion 52E to the left. However, as mentioned above, the sliding protrusion 52E cannot move to the left, so the rightward pressing force on the rear end inclined edge 31E causes the rotor 30 to rotate counterclockwise (see Figure 8 (A)).

Then, as the rotor 30 rotates counterclockwise, the sliding protrusion 52E in the engagement position moves from the engagement edge 31G to the left edge 31L, and is released from the engagement with the engagement edge 31G (see FIG. 8B).

Then, the sliding protrusion 52E, which has been released from the locking edge 31G, reaches the center portion 31B, and is moved back from the center portion 31B by the restoring force of the knock spring (not shown) (see FIG. 8(C)). As a result, the entire mechanical pencil refill 40 moves back, and the writing tip moves back from the tip opening 22A into the inside of the barrel 20.

Then, each knock button 51 retracts until it abuts against the knock button engaging edge 11A of the cover member 11, and each sliding protrusion 52E returns to its original standby position as shown in FIG. 2.

Next, the flow of releasing the state in which all knock rods 50 are knocked and all sliding protrusions 52E are in the locked position (hereinafter referred to as the "fully extended state") with the front tube 22 removed from the rear tube 21 (see FIG. 9) will be described. This fully extended state (see FIG. 9(B)) occurs when all knock rods 50 are knocked simultaneously in the state shown in FIG. 9(A) with the front tube 22 removed from the rear tube 21, or when the knocked knock rod 50 is held down with a finger while the other knock rods 50 are knocked in turn.

In the fully extended state, all of the sliding protrusions 52E are in the locking position and are locked to the locking edge 31G (see Figures 10(A) and 11(A)). In this embodiment, there are three sliding protrusions 52E, but the remaining one is not shown.

When the knock button 51 having the sliding protrusion 52E shown in Fig. 10 is advanced from this fully extended state, the sliding protrusion 52E advances through the release portion 31D and reaches the release inclined edge 31K. Thereafter, as described above, the rotor 30 rotates counterclockwise, and the sliding protrusion 52E in the locked position shown in Fig. 11(A) moves from the locking edge 31G toward the left edge 31L, and is released from the locking edge 31G as shown in Fig. 11(B). Thereafter, the sliding protrusion 52E, which has been released from the locking edge 31G, reaches the center portion 31B, and due to the restoring force of the knock spring (not shown), retreats from the center portion 31B (see Fig. 11(C)) to the rear end portion 31A and returns to the standby position. In this case, as shown in FIG. 9(C), the thermochromic writing instrument 10 is in a state in which one mechanical pencil refill 40 is fully extended and the other two mechanical pencil refills 40 are released.

On the other hand, when the knock button 51 having the sliding protrusion 52E shown in FIG. 10 is advanced from the release inclined edge 31K, the sliding protrusion 52E reaches the narrow tip portion 31M (see FIG. 10(B)), and the knock button 51 abuts against the tip of the sliding groove 21A, stopping the advancement of the sliding protrusion 52E. Then, when the sliding protrusion 52E reaches the narrow tip portion 31M and the knock button 51 abuts against the tip of the sliding groove 21A, the sliding protrusion 52E moves backward along the guide edge 31I to the right edge 31R side (see FIG. 10(C)) due to the restoring force of the knock spring (not shown), and stops its retreat when it abuts against the locking edge 31G (see FIG. 10(D)). That is, the sliding protrusion 52E is in the locking position.

When the sliding protrusion 52E shown in FIG. 10 is located in the locking position, the sliding protrusion 52E shown in FIG. 11, which was in the locking position, returns to the standby position as described above, and the fully extended state is released. Thereafter, as described above, the sliding protrusion 52E can be returned from the locking position to the standby position by advancing the knock button 51, which is in the standby position (see FIG. 10 (E) and (F)).

As described above, according to this embodiment, even when the reel is in the fully extended state, the reel can be released by moving the knock button 51, in which the sliding protrusion 52E is in the locked position, forward to rotate the rotor 30 counterclockwise.

In addition, in this embodiment, the rear end side of the guide edge 31I is inclined toward the right edge 31R side, so when the sliding protrusion 52E reaches the narrow tip portion 31M and the knock button 51 abuts against the tip of the sliding groove 21A, and pressure on the knock button 51 is released, the restoring force of the knock spring (not shown) causes the sliding protrusion 52E to retreat to the locking position. Therefore, according to this embodiment, the fully extended state is released, and the sliding protrusion 52E, which has returned to the standby position, can be released by advancing the knock button 51, which has the sliding protrusion 52E.

The writing lead 70 is a solid lead having thermochromic properties that can change color due to frictional heat contained within the mechanical pencil refill 40. To explain the writing lead 70 in detail, it is essential to have two components: (a) a thermochromic component, and (b) a component that controls the amount of heat transferred to the thermochromic component. The specific components are as follows.
(a) Thermochromic Component The thermochromic component used in the embodiment of the present invention (hereinafter, for the sake of simplicity, may be referred to as component (a)) includes components (a1) to (a3) described below. One such component (a) has the following characteristics and a relatively small hysteresis width (ΔH=1 to 7° C.).
(1) The color changes around a certain temperature (color change point), and the color disappears in a temperature range above the high-temperature color change point, and the color develops in a temperature range below the low-temperature color change point.
(2) In the normal temperature range, only one of the above-mentioned decolorized state and colored state exists.
(3) When the material is heated to a temperature above the high-temperature discoloration point or cooled to a temperature below the low-temperature discoloration point, it enters the other state, and this state is maintained as long as that temperature is maintained. However, when the heating or cooling is removed, the material returns to the state it exhibits at room temperature.

Also usable is a component (a) exhibiting a large hysteresis characteristic (ΔH _B =8 to 50° C.). That is, a component can be used in which the shape of the curve plotting the change in coloring density with temperature changes follows a path that is significantly different when the temperature is increased from a lower temperature side than the discoloration temperature range and when the temperature is decreased from a higher temperature side than the discoloration temperature range, and in which the colored state in a low temperature range below the complete coloring temperature (t ₁ ) or the decolored state in a high temperature range above the complete decolorization temperature (t ₄ ) has color memory in a specific temperature range [temperature range between t ₂ and t ₃ (substantially two-phase retention temperature range)]. This component may be of a heat-decoloring type (decolored by heating and colored by cooling) or may be encapsulated in a microcapsule.

In order to have only one specific state (colored state) of the color developing and decoloring states of component (a) exist in the room temperature range and to easily discolor (decolorize) handwriting made of component (a) by friction, it is preferable that the complete decolorization temperature ( _t4 ) is 45 to 95°C and the color development onset temperature ( _t2 ) is -50 to 10°C.

Here, the reason why the complete decolorization temperature (t ₄ ) is preferably 45 to 95° C. and the color development start temperature (t ₂ ) is preferably −50 to 10° C. so that the colored state can be maintained in the normal temperature range and the color change caused by friction of the handwriting can be easily prevented can be explained as follows: If heating is stopped before the complete decolorization temperature (t ₄ ) is reached after passing through the decolorization start temperature (t ₃ ) from the colored state, the phenomenon of returning to the first state occurs, and even if cooling is stopped before the complete color development temperature (t ₁ ) is reached after passing through the color development start temperature (t ₂ ), the colored state is maintained. Therefore, if the complete decolorization temperature (t ₄ ) is 45° C. or higher, which is above the normal temperature range, the colored state will be maintained under normal use conditions, and if the color development start temperature (t ₂ ) is −50 to 10° C., which is below the normal temperature range, the decolored state will be maintained under normal use conditions. Furthermore, when erasing handwriting by friction, if the complete decolorization temperature (t ₄ ) is 95° C. or lower, the handwriting formed on the writing surface can be sufficiently discolored by frictional heat generated by rubbing the surface with a friction member several times.

When the complete decolorization temperature (t ₄ ) is a temperature exceeding 95°C, the frictional heat obtained by the friction of the friction member is unlikely to reach the complete decolorization temperature, so that the color does not easily change, and the number of frictions increases, or there is a tendency for the friction to be overloaded, which may damage the writing surface. In setting the temperature of the above-mentioned complete decolorization temperature (t ₄ ), a higher temperature is preferable in order to maintain the color-developed state in normal use, and a lower temperature is preferable in order to make the frictional heat caused by friction exceed the complete decolorization temperature (t ₄ ). Therefore, the complete decolorization temperature (t ₄ ) is preferably 50 to 90°C, more preferably 60 to 80°C. Furthermore, in setting the temperature of the above-mentioned color development start temperature (t ₂ ), a lower temperature is preferable in order to maintain the decolored state in normal use, and -50 to 5°C is preferable, and -50 to 0°C is more preferable.

The hysteresis width (ΔH) of the writing lead 70 is generally in the range of 50 to 100°C, and preferably 60 to 80°C.

As the component (a1), so-called leuco dyes can be used. Specific examples include diphenylmethane phthalides, phenylindolyl phthalides, indolyl phthalides, diphenylmethane azaphthalides, phenylindolyl azaphthalides, fluorans, styrinoquinolines, and diazarhodamine lactones. More specific examples include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3,3-bis(1-n-butyl-2-methylindol-3-yl)phthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-[2-ethoxy-4-(N-ethylanilino)phenyl]-3-(1-ethyl-2-methylindol-3 -yl)-4-azaphthalide, 3,6-diphenylaminofluoran, 3,6-dimethoxyfluoran, 3,6-di-n-butoxyfluoran, 2-methyl-6-(N-ethyl-N-p-tolylamino)fluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 2-(2-chloroanilino)-6-di-n-butylaminofluoran, 2-(3-trifluoromethylanilino)-6-diethylaminofluoran, 2-(N -methylanilino)-6-(N-ethyl-N-p-tolylamino)fluoran, 1,3-dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-di-n-butylaminofluoran, 2-xylidino-3-methyl-6-diethylaminofluoran, 1,2-benz-6-diethylaminofluoran, 1,2-benz-6-(N-ethyl-N -isobutylamino)fluoran, 1,2-benz-6-(N-ethyl-N-isoamylamino)fluoran, 2-(3-methoxy-4-dodecoxystyryl)quinoline, spiro[5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran]-3'-one, 2-(diethylamino)-8-(diethylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidin-5,1'(3'H)isobenzofuran]-3-one, 2-( 2-(di-n-butylamino)-8-(di-n-butylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidin-5,1'(3'H)isobenzofuran]-3-one, 2-(di-n-butylamino)-8-(diethylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidin-5,1'(3'H)isobenzofuran]-3-one, 2-(di-n-butylamino)-8-(N-ethyl-N-i-amylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidin-5,1'(3'H)isobenzofuran]-3-one 2-(dibutylamino)-8-(dipentylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidin-5,1'(3'H)-isobenzofuran]-3-one, 3-(2-methoxy-4-dimethylaminophenyl)-3-(1-butyl-2-methylindol-3-yl)-4,5,6,7-tetrachlorophthalide, 3-(2-ethoxy- 4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4,5,6,7-tetrachlorophthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-pentyl-2-methylindol-3-yl)-4,5,6,7-tetrachlorophthalide, 4,5,6,7-tetrachloro-3-[4-(dimethylamino)-2-methylphenyl]-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofurano , 3',6'-bis[phenyl(2-methylphenyl)amino]-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, 3',6'-bis[phenyl(3-methylphenyl)amino]-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, and 3',6'-bis[phenyl(3-ethylphenyl)amino]-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one. Furthermore, pyridine-based, quinazoline-based, and bisquinazoline-based compounds that are effective in producing fluorescent yellow to red coloring can be mentioned, and an example of such compounds is 4-[2,6-bis(2-ethoxyphenyl)-4-pyridinyl]-N,N-dimethylbenzenamine.

The electron-accepting compound of component (a2) used in the embodiment of the present invention includes a group of compounds having an active proton, a group of pseudo-acidic compounds (a group of compounds that are not acids but act as an acid in the composition to cause component (a1) to develop color), and a group of compounds having an electron vacancy.

Examples of compounds having an active proton include compounds having a phenolic hydroxyl group, such as monophenols having one phenol group, as well as polyphenols having multiple phenol groups. Further examples include those having an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, a carboxyl group and its ester or amide group, a halogen group, etc. as a substituent, as well as bis-type and tris-type phenols, and phenol-aldehyde condensation resins. Metal salts of the compounds having a phenolic hydroxyl group can also be used. More specifically, phenol, o-cresol, tertiary butyl catechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcin, dodecyl gallate, 2,2-bis(4-hydroxyphenyl)propane, 4,4-dihydroxydiphenyl sulfone, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)sulfide, 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-3-methylbutane, 1,1-bis(4 2,2-bis(4-hydroxyphenyl)-2-methylpropane, 1,1-bis(4-hydroxyphenyl)n-hexane, 1,1-bis(4-hydroxyphenyl)n-heptane, 1,1-bis(4-hydroxyphenyl)n-octane, 1,1-bis(4-hydroxyphenyl)n-nonane, 1,1-bis(4-hydroxyphenyl)n-decane, 1,1-bis(4-hydroxyphenyl)n-dodecane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)ethylpropionate, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxyphenyl)n-heptane, and 2,2-bis(4-hydroxyphenyl)n-nonane.

In addition, the compounds having the phenolic hydroxyl group are capable of exhibiting the most effective thermal discoloration properties, but compounds selected from aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms, metal salts of carboxylic acids, acidic phosphate esters and their metal salts, 1,2,3-triazole and its derivatives, etc. can also be used.

Examples of component (a3) of the reaction medium that reversibly induces an electron transfer reaction between components (a1) and (a2) in a specific temperature range include alcohols, esters, ketones, and ethers.

Preferably, the component (a3) is a carboxylic acid ester compound that exhibits a ΔT value (melting point - cloud point) of 5°C or more and less than 50°C and can form a thermochromic composition that exhibits color memory and changes color while showing a large hysteresis characteristic (the curve plotting the change in color density due to temperature change is different when the temperature is changed from the low side to the high side and when the temperature is changed from the high side to the low side) in the color density - temperature curve, for example, a carboxylic acid ester containing a substituted aromatic ring in the molecule, an ester of a carboxylic acid containing an unsubstituted aromatic ring and an aliphatic alcohol having 10 or more carbon atoms in the molecule, Examples of usable compounds include carboxylic acid esters containing a cyclohexyl group, esters of fatty acids having 6 or more carbon atoms and unsubstituted aromatic alcohols or phenols, esters of fatty acids having 8 or more carbon atoms and branched aliphatic alcohols or esters, esters of dicarboxylic acids and aromatic alcohols or branched aliphatic alcohols, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, dicetyl adipate, distearyl adipate, trilaurin, trimyristin, tristearin, dimyristin, and distearin.

Furthermore, fatty acid ester compounds obtained from an odd-numbered aliphatic monohydric alcohol having 9 or more carbon atoms and an aliphatic carboxylic acid having an even number of carbon atoms, and fatty acid ester compounds having a total of 17 to 23 carbon atoms obtained from n-pentyl alcohol or n-heptyl alcohol and an even-numbered aliphatic carboxylic acid having 10 to 16 carbon atoms may be used. Specifically, examples of esters include n-pentadecyl acetate, n-tridecyl butyrate, n-pentadecyl butyrate, n-undecyl caproate, n-tridecyl caproate, n-pentadecyl caproate, n-nonyl caprylate, n-undecyl caprylate, n-tridecyl caprylate, n-pentadecyl caprylate, n-heptyl caprate, n-nonyl caprate, n-undecyl caprate, n-tridecyl caprate, n-pentadecyl caprate, n-pentyl laurate, n-heptyl laurate, n-nonyl laurate, n-undecyl laurate, n-tridecyl laurate, n-pentadecyl laurate, n-pentyl myristate, n-heptyl myristate, myristate, Examples of the oleic acid include n-nonyl oleate, n-undecyl myristate, n-tridecyl myristate, n-pentadecyl myristate, n-pentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-undecyl palmitate, n-tridecyl palmitate, n-pentadecyl palmitate, n-nonyl stearate, n-undecyl stearate, n-tridecyl stearate, n-pentadecyl stearate, n-nonyl eicosanoate, n-undecyl eicosanoate, n-tridecyl eicosanoate, n-pentadecyl eicosanoate, n-nonyl behenate, n-undecyl behenate, n-tridecyl behenate, and n-pentadecyl behenate.

As ketones, aliphatic ketones having a total carbon number of 10 or more are effective, and examples thereof include 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, 5-undecanone, 2-dodecanone, 3-dodecanone, 4-dodecanone, 5-dodecanone, 2-tridecanone, 3-tridecanone, 2-tetradecanone, 2-pentadecanone, 8-pentadecanone, 2-hexadecanone, 3-hexadecanone, 9-heptadecanone, 2-pentadecanone, 2-octadecanone, 2-nonadecanone, 10-nonadecanone, 2-eicosanone, 11-eicosanone, 2-heneicosanone, 2-docosanone, laurone, and stearone.

Furthermore, examples of aryl alkyl ketones having a total carbon number of 12 to 24 include n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecanophenone, 4-n-dodecaacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonylacetophenone, n-decanophenone, 4-n-octylacetophenone, and n-nonanoacetophenone. Phenone, 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butylpropiophenone, n-heptaphenone, 4-n-pentylacetophenone, cyclohexyl phenyl ketone, benzyl-n-butyl ketone, 4-n-butylacetophenone, n-hexanophenone, 4-isobutylacetophenone, 1-acetonaphthone, 2-acetonaphthone, and cyclopentyl phenyl ketone.

As ethers, aliphatic ethers having a total of 10 or more carbon atoms are effective, and examples of such ethers include dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditridecyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether, dioctadecyl ether, decanediol dimethyl ether, undecanediol dimethyl ether, dodecanediol dimethyl ether, tridecanediol dimethyl ether, decanediol diethyl ether, and undecanediol diethyl ether.

The blending ratio of the three components (a1), (a2), and (a3) contained in component (a) is determined by the color concentration, discoloration temperature, and type of each component, but the blending ratio that generally provides the desired properties is, in mass ratio, component (a1):component (a2):component (a3)=1:0.1-50:1-800, and preferably component (a1):component (a2):component (a3)=1:0.5-20:5-200. Two or more types of each of these components may be mixed and used.

The component (a) may be dispersed in the writing lead 70 as is, but is preferably used as a thermochromic microcapsule pigment encapsulated in a microcapsule (hereinafter sometimes referred to as a thermochromic microcapsule). This is because the thermochromic composition maintains the same composition under various conditions of use, and can provide the same functional effects.

In addition, any dye or pigment (non-thermochromic) can be added to the microencapsulated pigment to cause a color change (discoloration) from one color to a different color.

The method for microencapsulating the component (a) includes the interfacial polymerization method, the interfacial polycondensation method, the in situ polymerization method, the liquid hardening coating method, the phase separation method from an aqueous solution, the phase separation method from an organic solvent, the melt dispersion cooling method, the air suspension coating method, the spray drying method, etc., and is appropriately selected according to the application. Furthermore, a secondary resin film can be further provided on the surface of the microcapsules depending on the purpose to impart durability or to modify the surface properties for practical use.

The microcapsule pigment may have a circular cross section or a non-circular cross section. The mass ratio of component (a) to the microcapsule wall generally falls within the range of 7:1 to 1:1, and preferably 6:1 to 1:1. If the ratio of component (a) to the wall exceeds the above range, the wall becomes too thin, and resistance to pressure and heat is likely to decrease. If the ratio of the wall to component (a) exceeds the above range, the color density and clarity during color development are likely to decrease.

The microcapsule pigment generally satisfies practical use when the average particle size is in the range of 0.1 to 50 μm, preferably 0.3 to 30 μm, and more preferably 0.5 to 10 μm. If the average maximum outer diameter of the microcapsules exceeds 50 μm, the dispersion stability may be lacking, and if the average maximum outer diameter is less than 0.1 μm, it will be difficult to exhibit high-concentration color development, so care must be taken. The average particle size of the microcapsules referred to in this invention is expressed as the D50 value expressed on a volume basis when the outer diameter of the particles is measured, but here, the value measured using a laser diffraction/scattering type particle size distribution measuring device LA-300 (manufactured by Horiba, Ltd.; LA-300) and the average particle size (median size) calculated based on the numerical value is used.

(b) The component that controls the amount of heat transferred to the thermochromic component is the thermochromic component (a) described above, which changes color or fades when exposed to heat from the outside, causing the color of the entire composition to change. At this time, by controlling the amount of heat applied to component (a), it is possible to prevent unintended discoloration or fade. For the sake of simplicity, hereinafter, such a component that controls the amount of heat transferred to component (a) may be referred to as component (b).

Component (b) includes
(1) Those that suppress the amount of heat generated by friction, etc., and (2) those that absorb heat applied from the outside and suppress the transfer of the heat to component (a). In either case, the amount of heat applied to component (a) is controlled, and unintended discoloration or fading of component (a) can be prevented.

Examples of the component (b) having such a function include:
(bi) an ester compound selected from the group consisting of sucrose fatty acid esters and dextrin fatty acid esters, and (bii) an endothermic phase change compound that always exists in an incompatible state with component (a) and has a melting point lower than that of component (a3). These (bi) and (bii) have at least one of the functions (1) or (2) above, but are not limited to those having only one of the functions (1) or (2). For example, component (bi) mainly exerts the function (1) above, but is also considered to have the function (2). Each of the components (b) is explained below.

As component (bi), an ester compound selected from the group consisting of sucrose fatty acid esters and dextrin fatty acid esters can be used. By using such a component, it is possible to prevent unintended discoloration or fading of component (a) and improve writing properties. That is, since sucrose fatty acid esters and dextrin fatty acid esters have a relatively low melting point, it is presumed that they soften during writing and absorb the friction resistance. Therefore, by adding them to the composition, writing resistance is reduced and heat generation is suppressed. For example, when writing quickly using a conventional thermochromic writing lead 70, the heat generation temperature caused by friction with the paper surface increases, causing component (a) to become transparent, and the handwriting previously formed may be discolored. In contrast, in an embodiment of the present invention, the addition of the ester compound can reduce the heat generation caused by friction with the paper surface during writing, and the problem of the handwriting being discolored due to frictional heat generated during high-speed writing can be suppressed, making it possible to write quickly.

Furthermore, it is possible to apply multiple layers of writing, making it easy to create shading on the paper surface. This makes it useful for serious coloring applications, such as adult coloring books, for which demand has recently increased in the market.

As the sucrose fatty acid ester that can be used above, esters having _C12 to _C22 fatty acids as constituent fatty acids are particularly suitable, and palmitic acid and stearic acid are more preferable. Specific examples include the Ryoto Sugar Ester (trade name) series (manufactured by Mitsubishi Chemical Foods Corporation) and the Sugar Wax (trade name) series (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

As the dextrin fatty acid ester that can be used above, particularly esters containing _C14 to _C18 fatty acids as constituent fatty acids are suitable, and palmitic acid, myristic acid, and stearic acid are more useful. Specific examples include the Leopearl (trade name) series (manufactured by Chiba Flour Milling Co., Ltd.).

(bii) An endothermic phase change compound can be used as an endothermic phase change compound that always exists in an incompatible state with component (a) and has a melting point lower than that of component (a3). This compound mainly has the effect of absorbing heat and suppressing the transfer of heat to component (a). This compound must exist in an incompatible state with component (a) and have a melting point lower than that of component (a3). Specifically, compounds that can be used as component (bii) have a melting point lower than that of component (a3). Specific examples of compounds that can be used include organic compounds such as alcohols, carboxylic acids, esters, ethers, ketones, and amides. More specifically, examples of alcohols include lauryl alcohol, dodecyl alcohol, myristyl alcohol, pentadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, behenyl alcohol, ceryl alcohol, melissyl alcohol, polyethylene glycol, and polypropylene glycol. Examples of carboxylic acids include lauric acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, nonadecylic acid, eicosanoic acid, and behenic acid/tetracosanoic acid. Examples of esters include esters having a total of 13 or more carbon atoms composed of a monovalent fatty acid and an aliphatic monohydric alcohol, or an alicyclic monohydric alcohol, such as pentadecyl acetate, n-tridecyl butyrate, n-pentadecyl butyrate, n-nonyl caprylate, n-undecyl caprylate, n-lauryl caprylate, n-tridecyl caprylate, n-pentadecyl caprylate, cetyl caprylate, stearyl caprylate, and capric acid. n-propyl, n-heptyl caprate, n-undecyl caprate, n-lauryl caprate, n-tridecyl caprate, n-pentadecyl caprate, cetyl caprate, stearyl caprate, n-undecyl caproate, n-tridecyl caproate, n-pentadecyl caproate, n-nonyl caproate, n-undecyl caproate, stearyl caproate, n-hexyl caprylate, n-caprylate -heptyl, n-octyl caprylate, methyl laurate, n-heptyl laurate, n-pentyl laurate, neopentyl laurate, 2-ethylhexyl laurate, n-octyl laurate, n-nonyl laurate, n-decyl laurate, n-undecyl laurate, lauryl laurate, n-tridecyl laurate, myristyl laurate, n-pentadecyl laurate, stearyl laurate, cyclohexyl methyl laurate, methyl myristate, n-pentyl myristate, n-heptyl myristate, n-nonyl myristate, n-decyl myristate, n-undecyl myristate, lauryl myristate, n-tridecyl myristate, myristyl myristate, n-pentadecyl myristate, cetyl myristate, stearyl myristate, cyclohexyl myristate, methyl palmitate ethyl palmitate, n-propyl palmitate, n-pentyl palmitate, neopentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-decyl palmitate, n-undecyl palmitate, lauryl palmitate, n-tridecyl palmitate, myristyl palmitate, n-pentadecyl palmitate, cetyl palmitate, stearyl palmitate, cyclohexylmethyl palmitate, methyl stearate, n-amyl stearate, n-heptyl stearate, neopentyl stearate, n-octyl stearate, n-nonyl stearate, n-decyl stearate, n-undecyl stearate, n-tridecyl stearate, myristyl stearate, n-pentadecyl stearate, cetyl stearate, stearyl stearate, eicosyl stearate, stearyl n-Docosyl eicosanoate, Cyclohexylmethyl stearate, Oleyl stearate, Isostearyl stearate, Cyclohexylmethyl stearate, Methyl eicosanoate, n-Amyl eicosanoate, n-Heptyl eicosanoate, n-Octyl eicosanoate, n-Nonyl eicosanoate, n-Decyl eicosanoate, n-Undecyl eicosanoate, n-Tridecyl eicosanoate, n-Pentadecyl eicosanoate, Becosanoate Examples include ethyl behenate, n-amyl behenate, n-heptyl behenate, neopentyl behenate, n-octyl behenate, n-nonyl behenate, n-decyl behenate, n-undecyl behenate, n-tridecyl behenate, myristyl behenate, n-pentadecyl behenate, cetyl behenate, stearyl cyclohexylacetate, stearyl 2-cyclohexylpropionate, and neopentyl octylate.

Furthermore, as esters consisting of an aliphatic divalent or polyvalent carboxylic acid and an aliphatic monovalent alcohol or a monovalent alcohol having an alicyclic ring and a total carbon number of 18 or more, di-n-butyl sebacate, di-n-hexyl adipate, di-n-nonyl oxalate, di-n-decyl oxalate, di-n-undecyl oxalate, dilauryl oxalate, di-n-tridecyl oxalate, dimyristyl oxalate, di-n-pentadecyl oxalate, dicetyl oxalate, di-n-heptadecyl oxalate, distearyl oxalate, dilauryl malonate, di-n-tridecyl malonate, dimyristyl malonate, di-n-pentadecyl malonate, dicetyl malonate, di-n-heptadecyl malonate, distearyl malonate, di-n-nonyl succinate, di-n-pentadecyl malonate, dicetyl malonate, di-n-heptadecyl malonate, distearyl malonate, di-n-nonyl succinate, n-Decyl, di-n-undecyl succinate, dilauryl succinate, di-n-tridecyl succinate, dimyristyl succinate, di-n-pentadecyl succinate, dicetyl succinate, diheptadecyl succinate, distearyl succinate, di-n-decyl glutarate, di-n-undecyl glutarate, dilauryl glutarate, di-n-tridecyl glutarate, dimyristyl glutarate, di-n-pentadecyl glutarate, dicetyl glutarate, di-n-heptadecyl glutarate, distearyl glutarate, di-n-decyl adipate, di-n-undecyl adipate, dilauryl adipate, di-n-tridecyl adipate, dimyristyl adipate, di-n-pentadecyl adipate, dicetyl adipate, adipic acid Di-n-heptadecyl, distearyl adipate, di-n-docosyl adipate, di-n-decyl pimelate, di-n-undecyl pimelate, dilauryl pimelate, di-n-tridecyl pimelate, dimyristyl pimelate, di-n-pentadecyl pimelate, dicetyl pimelate, di-n-heptadecyl pimelate, distearyl pimelate, di-n-decyl suberate, di-n-undecyl suberate, dilauryl suberate, di-n-tridecyl suberate, dimyristyl suberate, di-n-nonyl sebacate, di-n-decyl sebacate, di-n-undecyl sebacate, dilauryl sebacate, di-n-tridecyl sebacate, dimyristyl sebacate, di-n-pentadecyl sebacate, sebacine dicetyl ester, di-n-heptadecyl sebacate, distearyl sebacate, di-n-pentadecyl suberate, dicetyl suberate, di-n-heptadecyl suberate, distearyl suberate, di-n-decyl azelate, di-n-undecyl azelate, dilauryl azelate, di-n-tridecyl azelate, dimyristyl azelate, di-n-pentadecyl azelate, dicetyl azelate, di-n-heptadecyl azelate, distearyl azelate, di-n-octyl 1,18-octadecyl methylene dicarboxylate, dicyclohexyl 1,18-octadecyl methylene dicarboxylate, and dineopentyl 1,18-octadecyl methylene dicarboxylate.

Furthermore, examples of esters consisting of aliphatic dihydric or polyhydric alcohols or alicyclic dihydric or polyhydric alcohols and monohydric fatty acids with a total carbon number of 18 or more include ethylene glycol dicaprylate, ethylene glycol dicaprate, ethylene glycol diundecanoate, ethylene glycol dilaurate, ethylene glycol ditridecanoate, ethylene glycol dimyristate, ethylene glycol dipentadecanoate, ethylene glycol dipalmitate, ethylene glycol diheptadecanoate, ethylene glycol distearate, 1,3-propanediol, dicaprylic acid ester, 1,3-propanediol dicapric acid ester, 1,3-propanediol diundecanoic acid ester, 1,3-propanediol dilauric acid ester, 1,3-propanediol ditridecanoic acid ester, 1,3-propanediol dimyristic acid ester, 1,3-propanediol dipentadecanoic acid ester, 1,3-propanediol dipalmitic acid ester, 1,3-propanediol diheptadecanoic acid ester, 1,3-propanediol distearic acid ester, 1,4-butanediol dicaprylic acid ester, 1,4-butanediol dicapric acid ester, 1,4-butanediol di Undecanoic acid ester, 1,4-butanediol dilaurate, 1,4-butanediol ditridecanoic acid ester, 1,4-butanediol dimyristate, 1,4-butanediol dipentadecanoic acid ester, 1,4-butanediol dipalmitate, 1,4-butanediol diheptadecanoic acid ester, 1,4-butanediol distearate, 1,5-pentanediol dicaprate, 1,5-pentanediol diundecanoic acid ester, 1,5-pentanediol dilaurate, 1,5-pentanediol ditridecanoic acid ester, 1,5-pentanediol dimyristate acid ester, 1,5-pentanediol dipentadecanoic acid ester, 1,5-pentanediol dipalmitic acid ester, 1,5-pentanediol diheptadecanoic acid ester, 1,5-pentanediol distearic acid ester, 1,6-hexanediol dicapric acid ester, 1,6-hexanediol diundecanoic acid ester, 1,6-hexanediol dilauric acid ester, 1,6-hexanediol ditridecanoic acid ester, 1,6-hexanediol dimyristic acid ester, 1,6-hexanediol dipentadecanoic acid ester, 1,6-hexanediol dipalmitic acid ester, 1,6-hexanediol diheptadecanoic acid ester, butadecanoic acid ester, 1,6-hexanediol distearate, 1,7-pentanediol dicaprate, 1,7-pentanediol diundecanoic acid ester, 1,7-pentanediol dilaurate, 1,7-pentanediol ditridecanoic acid ester, 1,7-pentanediol dimyristate, 1,7-pentanediol dipentadecanoic acid ester, 1,7-pentanediol dipalmitate, 1,7-pentanediol diheptadecanoic acid ester, 1,7-pentanediol distearate, 1,8-octanediol dicaprate, 1,8-octanediol diundecanoic acid ester, 1,8-octanediol dilaurate, 1,8-octanediol ditridecanoic acid ester, 1,8-octanediol dimyristate, 1,8-octanediol dipentadecanoic acid ester, 1,8-octanediol dipalmitate, 1,8-octanediol diheptadecanoic acid ester, 1,8-octanediol distearate, 1,9-nonanediol dicaprate, 1,9-nonanediol diundecanoic acid ester, 1,9-nonanediol dilaurate, 1,9-nonanediol ditridecanoic acid ester, 1,9-nonanedi ... Listic acid ester, 1,9-nonanediol dipentadecanoic acid ester, 1,9-nonanediol dipalmitic acid ester, 1,9-nonanediol diheptadecanoic acid ester, 1,9-nonanediol distearic acid ester, 1,10-decanediol dicaprylic acid ester, 1,10-decanediol dicapric acid ester, 1,10-decanediol diundecanoic acid ester, 1,10-decanediol dilauric acid ester, 1,10-decanediol ditridecanoic acid ester, 1,10-decanediol dimyristic acid ester, 1,10-decanediol dipentadecanoic acid ester, 1,10-decanediol dipalmitic acid ester These include mitate ester, 1,10-decanediol diheptadecanoate ester, 1,10-decanediol distearate ester, 1,5-pentanediol distearate, 1,2,6-hexanetriol dimyristate, pentaerythritol trimyristate, pentaerythritol tetralaurate, 1,4-cyclohexanediol dimyristyl, 1,4-cyclohexanediol didecyl, 1,4-cyclohexanediol dimyristyl, 1,4-cyclohexanediol distearyl, 1,4-cyclohexanedimethanol dilaurate, and 1,4-cyclohexanedimethanol dimyristate.

Esters consisting of dihydric alcohols with aromatic rings and monohydric fatty acids and having a total of 24 or more carbon atoms include xylylene glycol dicaprylate, xylylene glycol dicaprate, xylylene glycol diundecanoate, xylylene glycol dilaurate, xylylene glycol ditridecanoate, xylylene glycol dimyristate, xylylene glycol dipentadecanoate, xylylene glycol dipalmitate, xylylene glycol diheptadecanoate, and xylylene glycol distearate.

Furthermore, examples of esters having a total carbon number of 15 or more, which are composed of a monovalent carboxylic acid having an aromatic ring and an aliphatic monohydric alcohol or a monohydric alcohol having an alicyclic ring, include hexyl 3,5-dimethylbenzoate, decyl 2-methylbenzoate, lauryl 2-methylbenzoate, myristyl 2-methylbenzoate, stearyl 2-methylbenzoate, cetyl 4-tert-butylbenzoate, behenyl 4-cyclohexylbenzoate, myristyl 4-phenylbenzoate, lauryl 4-octylbenzoate, stearyl 3-ethylbenzoate, decyl 4-isopropylbenzoate, stearyl 4-benzoylbenzoate, stearyl 4-chlorobenzoate, myristyl 3-bromobenzoate, stearyl 2-chloro-4-bromobenzoate, 3,4-dichlorobenzoate, stearyl 4-chlorobenzoate, stearyl 3-bromobenzoate, stearyl 2-chloro-4-bromobenzoate, stearyl 3- ... Decyl benzoate, octyl 2,4-dibromobenzoate, cetyl 3-nitrobenzoate, cyclohexylmethyl 4-aminobenzoate, cetyl 4-diethylaminobenzoate, stearyl 4-anilinobenzoate, decyl 4-methoxybenzoate, cetyl 4-methoxybenzoate, octyl 4-butoxybenzoate, cetyl 4-hydroxybenzoate, stearyl p-chlorophenylacetate, cetyl p-chlorophenylacetate, neopentyl salicylate, stearyl 2-naphthoate, cetyl benzilate, stearyl benzilate, decyl 3-benzoylpropionate, stearyl benzoate, myristyl benzoate, cyclohexylmethyl 2-benzoylpropionate, and cyclohexylmethyl cinnamate.

Furthermore, examples of esters having a total of 14 or more carbon atoms consisting of a monovalent carboxylic acid having an aromatic ring and a monohydric alcohol having an aromatic ring include benzyl salicylate, 4-methoxymethylphenylmethyl salicylate, 4-chlorophenylmethyl benzoate, benzyl cinnamate, phenyl 4-tert-butylbenzoate, 4-chlorobenzyl 2-methylbenzoate, and 4-methoxyphenylmethyl benzoate.

Examples of esters consisting of monovalent fatty acids and monovalent alcohols having an aromatic ring and having a total carbon number of 15 or more include 4-chlorophenylmethyl caprylate, 4-chlorophenylmethyl caprate, 4-methoxyphenylmethyl laurate, 4-methoxyphenylmethyl myristate, 4-nitrophenylmethyl stearate, 4-methylphenylmethyl caprate, 2-chlorophenylmethyl myristate, 4-chlorophenyl 11-bromolaurate, 4-isopropylphenyl stearate, stearyl 2-naphthoate, cetyl benzilate, stearyl benzilate, benzyl caproate, benzyl palmitate, 3-phenylpropyl stearate, and 11-bromo phenyl laurate.

Examples of esters with a total of 16 or more carbon atoms consisting of divalent fatty acids and monohydric alcohols with aromatic rings include dibenzyl sebacate and dineopentyl 4,4'-diphenyldicarboxylate.

Furthermore, component (bii) can be selected from among those listed as component (a3). In other words, when one material is selected as component (a3), any material with a lower melting point than that can be used as component (bii). The melting point of component (bii) must be lower than that of component (a3), but the difference in melting point is preferably about 3 to 70°C. If it is higher than this range, the absorption of thermal energy begins at a temperature lower than the temperature at which decolorization begins, so the blending ratio of component (bii) may be increased, and if it is lower than this range, the absorption of thermal energy by component (bii) becomes small when the decolorization start temperature is reached, and decolorization may begin. If it is within the above range, it is preferable because unnecessary decolorization of handwriting can be prevented.

Furthermore, to make the effect more pronounced, the blending ratio of component (a3) to component (bii) is component (a3):component (bii) = 1:0.1-3 by mass, and preferably component (a3):component (bii) = 1:0.3-2. If it is smaller than this range, the amount of heat that component (bii) can absorb is reduced, and there is a risk that discoloration cannot be prevented, whereas if it is larger than this range, the proportion of component (a) is reduced, and there is a tendency for the color density to decrease. If it is within this range, the color density of the handwriting is sufficient and unintended discoloration can be prevented, which is preferable.

When component (bii) is included, it is necessary that it and component (a) always exist in an incompatible state, but this can be achieved by separating them with an impermeable material. Specifically, component (a) and component (bii) are separated by a resin that is incompatible with both of them. A more preferred method is to encapsulate either component (a) or component (bii) in a microcapsule to make the two incompatible. More preferably, each of components (a) and (bii) is encapsulated in a microcapsule to make the two incompatible. In this state, it is particularly preferable because it is easy to process when making it into a writing core 70 or a writing water-based ink composition. In addition, it is possible to achieve both the expression of the heat absorbing effect and the effect of preventing deformation due to environmental temperature. The microcapsules encapsulating component (bii) (hereinafter sometimes referred to as heat absorbing capsules) preferably have an average particle size of 0.5 to 50 μm, although there is no particular limitation. If the particle size is smaller than this range, the ratio of the wall material to the microcapsules tends to be high and the ratio of component (bii) tends to be low. If the particle size is larger than this range, the surface area of the microcapsules is small, which impairs the heat absorbing effect, and when used in a writing ink composition or writing lead 70, the dispersion stability and processability tend to be poor. More preferably, the particle size is 1 to 30 μm, and even more preferably, 1 to 20 μm. If the particle size is within this range, the heat absorbing effect is good, and the dispersion stability and processability are improved. The method for measuring the average particle size is the same as the method used for the microcapsules containing component (a). Also, component (bi) and component (bii) can be used in combination. By combining these, component (bi) suppresses the generation of frictional heat, and component (bii) absorbs the generated heat, resulting in a synergistic effect.

Other additives may include various additives such as antioxidants, ultraviolet absorbers, infrared absorbers, dissolution aids, preservatives, or antifungal agents, provided that their functions are not affected. These may be selected from any of the conventionally known additives. A hindered amine compound may also be added. The addition of a hindered amine compound has the characteristic that the residual image of the erased writing area becomes even less visible. This is preferable because it does not impair the appearance of the written surface, yet satisfies re-writability and enhances marketability. Specific examples of such hindered amine compounds are as follows: Bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidylsebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl), tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate ester, mixed ester of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, mixed ester of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 1-tridecanol, 1,2,2,6,6-pentamethyl-4-piperidyl-methacrylate, N,N',N'',N'''-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine, N-methyl-3-dodecyl poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{2,2,6,6-tetramethyl-4-piperidyl}imino]hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}, polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and N,N',N'',N'''-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazine- Examples include a one-to-one reaction product of dibutylamine, 1,3-triazine, N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, a reaction product of decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester (1,1-dimethylethyl hydroperoxide) and octane, and a reaction product of cyclohexane and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine-2,4,6-trichloro-1,3,5-triazine peroxide with 2-aminoethanol.

The thermochromic composition used in the writing lead 70 is preferably 10 to 70% by mass relative to the total mass of the writing lead 70. If it is less than this range, the color density tends to be low, and if it is more than this range, the strength of the writing lead 70 tends to decrease. It is preferably 10 to 50% by mass, and more preferably 10 to 40% by mass, and within this range, it is possible to achieve both the strength of the writing lead 70 and the writing density.

Here, it is particularly preferable from the viewpoint of processability and the like that the component (a) is incorporated into the thermochromic composition in a microcapsule-encapsulated state and then applied to the writing lead 70. This embodiment is also preferable in that the composition of the thermochromic composition is kept constant under various conditions of use, and the same action and effect can be achieved.

In addition, although the writing lead 70 always exists in a solid state, if it contains a certain amount of a component with a relatively low melting point such as component (bii), there is a risk of deformation due to softening or melting in an environment with a relatively high temperature such as summer. It is particularly preferable to use component (bii) in a microencapsulated state, since it is possible to achieve both the expression of the heat absorbing effect and the effect of preventing deformation due to the environmental temperature. On the other hand, it is also possible to use component (bi) in a microencapsulated state, but in this case, the effect of component (bi) in reducing the writing resistance is reduced, so it is preferable to add component (bi) directly to the composition.

From the viewpoint of strength as the writing core 70, the thermochromic composition is preferably dispersed in a filler and solidified. The filler is for maintaining the shape of the writing core 70, and examples thereof include wax, gelling agent, clay, etc. As the wax, any conventionally known wax may be used, and specific examples thereof include carnauba wax, Japan wax, beeswax, microcrystalline wax, montan wax, candelilla wax, low molecular weight polyethylene, paraffin wax, etc. As the gelling agent, conventionally known gelling agents may be used, and examples thereof include 12-hydroxystearic acid, dibenzylidene sorbitols, tribenzylidene sorbitols, amino acid oils, and alkali metal salts of higher fatty acids. Examples of clay minerals include bentonite and montmorillonite. The above materials are used alone or in combination. Among such fillers, polyolefin wax is preferred from the viewpoints of availability and ease of handling.

Specific examples of the polyolefin wax include waxes such as polyethylene, polypropylene, polybutylene, α-olefin polymers, ethylene-propylene copolymers, and ethylene-butene copolymers.

In particular, the polyolefin wax having a softening point in the range of 100°C to 130°C and a penetration index of 0.25 or less is useful because it provides a high writing feel. The penetration index is specified in JIS K2207, and is the length of penetration when a needle of a specified weight is vertically inserted into the polyolefin wax at a temperature of 25°C, a load of 100 g, and a penetration time of 5 seconds. The penetration index value is expressed as 1 for 0.1 mm. Therefore, the smaller the penetration index, the harder the polyolefin wax is, and the larger the penetration index, the softer the polyolefin wax is. Among the polyolefin waxes, acid-modified polyethylene wax is particularly suitable. Since acid-modified polyethylene wax has a moderate viscosity (elasticity), it is assumed that it absorbs the abrasion resistance during writing. Therefore, the writing resistance is reduced and the writing feel is improved.

When using polyolefin wax as a filler, the blending ratio is preferably 0.2 to 70% by mass relative to the total mass of the writing lead 70. If it is less than this range, there is a tendency for the strength of the writing lead 70 to be insufficient, and if it is more than this range, there is a tendency for it to be difficult to obtain sufficient writing density. It is preferably 0.5 to 40% by mass, and within this range, it is possible to achieve both strength and writing density of the writing lead 70.

The writing core 70 may contain various additives as necessary. Examples of additives include fillers, viscosity regulators, fungicides, preservatives, antibacterial agents, and fragrances. Any conventionally known filler may be used as the filler, such as talc, clay, silica, calcium carbonate, barium sulfate, alumina, mica, boron nitride, potassium titanate, glass flakes, and starch. In particular, talc and calcium carbonate are preferred from the standpoint of moldability. The filler is blended to improve the strength of the writing core 70 of the embodiment of the present invention and to adjust the writing feel. In addition, any dye or pigment (non-thermochromic) may be added to the writing core 70 to cause a color change (discoloration) from a colored to a different color.

When the above-mentioned hindered amine compound is used, it is preferable to contain 0.1 to 5 mass% of the hindered amine compound based on the total mass of the writing lead 70. More specifically, when the writing lead 70 is a crayon, it is preferable to contain 10 to 60 mass% of component (a), preferably 20 to 50 mass%, 30 to 70 mass% of a filler, preferably 40 to 70 mass%, 5 to 30 mass% of a body material, and 0.1 to 5 mass% of a hindered amine compound in the total amount of the writing lead 70. When the writing lead 70 is a pencil lead or a lead for a mechanical pencil, it is preferable to contain 10 to 60 mass% of component (a), preferably 20 to 50 mass%, 10 to 40 mass% of a filler, 10 to 70 mass% of a body material, preferably 20 to 60 mass%, and 0.1 to 5 mass% of a hindered amine compound in the total amount of the writing lead 70.

Figure 12 is a rear perspective view of the thermochromic writing instrument 10 of this embodiment with the cover member 11 removed from the rear tube 21. A cylindrical mounting portion 21B is formed at the rear end of the rear tube 21. On the outer circumferential surface of the mounting portion 21B, there is formed an engagement portion 21C that engages with the cover member 11 to enable attachment and detachment, and a sloped portion 21D of a generally inverted triangular shape that narrows in diameter toward the rear. In this embodiment, the engagement portion 21C and sloped portion 21D are formed at three locations at equal intervals. It is preferable to form the engagement portion 21C and sloped portion 21D in at least two locations.

The friction member 60 is removably press-fitted and engaged on the inner circumferential surface of the attachment portion 21B, and a slit 21E is formed in one location that connects the outer circumferential surface and the inner circumferential surface of the attachment portion 21B to facilitate the attachment and removal of the friction member 60. By making the friction member 60 removable, it can be easily replaced even if it wears down due to thermal discoloration of the handwriting, and it can be used in a variety of ways.

The cover member 11 is detachably fitted over the mounting portion 21B of the rear tube 21, and by rotating the cover member 11 and the rear tube 21, which is the rear part of the shaft tube 20, relative to each other, the inclined surface 11D on the inner surface of the cover member 11 comes into contact with the inclined portion 21D and moves along it, causing the protrusion 11C to ride over the fitting portion 21C rearward and become unfitted, and the cover member 11 and the rear tube 21 are separated, which means that it can be removed.

It is preferable that the force required to remove the cover member 11 from the shaft tube 20 be smaller in the rotational direction than in the axial direction. It is even more preferable that the force required to remove the cover member 11 in the rotational direction be less than 0.02 N·m.

The friction member 60 is press-fitted and engaged into the inner surface of the attachment portion 21B, and the rear end surface is formed into a convex curved shape so as to easily apply frictional heat to the handwriting. Materials that can be used to form the friction member 60 include rubber materials such as silicone rubber, nitrile rubber, ethylene propylene rubber, and ethylene propylene diene rubber, rubber elastic materials such as thermoplastic elastomers such as styrene-based elastomers, olefin-based elastomers, and polyester-based elastomers, mixtures of two or more types of rubber elastic materials, mixtures of rubber elastic materials and synthetic resins, commercially available erasers, etc.

The friction member 60 is also formed to wear moderately so as not to damage the paper surface or blur the printed characters. Specifically, it is preferable that the Taber abrasion amount is 10 mg or more when using the abrasion wheel CS-17 of the Taber abrasion tester under the abrasion test (ASTM D1044) specified in JIS K7204 at a load of 9.8 N and 1000 rpm.

Furthermore, it is more preferable to apply an antistatic agent to the friction member 60 to prevent adhesion of dirt such as dust in the air and fibers on the paper surface when not in use. The antistatic agent is preferably a fatty acid ester of a polyhydric alcohol or a polycondensate thereof, or a sorbitan fatty acid ester, specifically decaglyceryl monostearate, decaglyceryl monostearate, pentaerythritol stearate, sorbitan monostearate, or sorbitan monooleate, etc., at 0.1 to 10 wt%, ideally 0.5 to 5 wt%, which can prevent dirt without impairing discoloration performance.

Figures 13 (A) to (G) are component diagrams of the cover member 11. The cover member 11 is composed of a cylindrical portion 11B formed with a generally triangular cross section, a flange portion 11E having a knock button locking edge 11A at the front of the cylindrical portion 11B, and a ceiling portion 11J at the rear. A rib-like protrusion 11F is formed at a location of large curvature on the outer peripheral surface of the cylindrical portion 11B. By forming two or more rib-like protrusions 11F in the axial direction, it becomes easier for fingers to get caught in the rotation direction, which has the effect of facilitating rotation to remove the cover member 11. A through hole 11G that connects the inner and outer surfaces of the cover member 11 is formed at the center of the ceiling portion 11J, which prevents choking even if the cover member 11 is accidentally swallowed. The inner peripheral surface of the cylindrical portion 11B is provided with protrusions 11C that are formed in the same number as the fitting portions 21C and that fit into the fitting portions 21C of the rear cylinder 21, inclined surfaces 11D that are inclined with respect to the axis that abuts against the inclined portions 21D of the mounting portion 21B when the cover member 11 is removed by rotation, connection surfaces 11I that connect one end between the multiple inclined surfaces 11D on the front side, and recesses 11H that connect the other end on the rear side. The recesses 11H and connection surfaces 11I are formed in the same number as the inclined portions 21. In addition, the recesses 11H are formed on the same axis as the protrusions 11C. When the cover member 11 is fitted into the shaft tube 20, the protrusions 11C are in a state where they ride up the fitting portions 21C forward, and the inclined portions 21D are arranged in an area surrounded by the inclined surfaces 11D, the recesses 11H, and the inclined surfaces 11D.

The material of the cover member 11 is a plastic material that is different from and harder than the friction member 60. More specifically, it uses 50% by mass or more of polypropylene resin. This characteristic not only prevents the friction member 60 from becoming dirty, but also makes it easy to erase handwriting made with thermochromic ink.

The polypropylene-based resin that can be used is the base material of the shaft, and examples thereof include propylene homopolymers; copolymers (including block copolymers and random copolymers) of propylene and small amounts of other α-olefins (e.g., ethylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc.); and the like. The polypropylene-based resin may be one or a mixture of two or more of these. The effects of the present invention can be achieved by using 50% by mass or more of the polypropylene-based resin in the total amount of the shaft, and the effects of the present invention cannot be achieved if the polypropylene-based resin is less than 50% by mass.

Other than the polypropylene resin, examples of resins that can be used include polyethylene and ionomer. In order to further enhance the effects of the present invention, it is preferable that these resins account for 0.5 to 30% by mass of the total shaft weight.

In addition, it is preferable to contain at least one resin selected from rosin-based resin, terpene-based resin, petroleum-based resin, phenol-based resin, coal-based resin, and xylene-based resin in order to adjust the adhesiveness and generate sufficient frictional heat even with light force. Among these resins, those with molecular weights of several hundred to several thousand are selected, and by blending them with the polypropylene-based resin, which is the main component, the shaft is given adhesiveness and the effect can be further exerted. Specifically, the above various resins, such as natural resins such as rosin-based resin and terpene-based resin, petroleum-based resin, phenol-based resin, coal-based resin, and xylene-based resin, with molecular weights of preferably 500 to 5,000, more preferably 700 to 4,000, can be used.

Examples of rosin-based resins include gum rosin, tall oil rosin, wood rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, glycerin of modified rosin, pentaerythritol ester, etc., and examples of terpene-based resins include terpene resins such as α-pinene, β-pinene, and dipentene-based resins, aromatic modified terpene resins, terpene phenol resins, and hydrogenated terpene resins. Among these resins, polymerized rosin, terpene resins, hydrogenated terpene resins, aromatic modified hydrogenated terpene resins, and terpene phenol resins are preferred from the viewpoint of further stability.

Petroleum-based resins are obtained, for example, by polymerizing a mixture of cracked oil fractions containing unsaturated hydrocarbons such as olefins and diolefins, which are by-produced together with petrochemical basic raw materials such as ethylene and propylene, by thermal cracking of naphtha in the petrochemical industry, with a Friedel-Crafts catalyst. Examples of such petroleum-based resins include aliphatic petroleum resins obtained by (co)polymerizing a _C5 fraction obtained by thermal cracking of naphtha, aromatic petroleum resins obtained by (co)polymerizing a _C9 fraction obtained by thermal cracking of naphtha, copolymerized petroleum resins obtained by copolymerizing the _C5 fraction and the _C9 fraction, alicyclic compound-based petroleum resins such as hydrogenated petroleum resins and dicyclopentadiene-based petroleum resins, and styrene-based resins such as copolymers of styrene, substituted styrene, and styrene with other monomers. The _C5 fraction obtained by thermal cracking of naphtha usually includes olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. In addition, aromatic petroleum resins obtained by (co)polymerizing _C9 fractions are resins obtained by polymerizing aromatics having 9 carbon atoms, with vinyltoluene and indene as the main monomers. Specific examples of _C9 fractions obtained by thermal cracking of naphtha include styrene homologues such as α-methylstyrene, β-methylstyrene, and γ-methylstyrene, and indene homologues such as indene and coumarone. Product names include Petrozin manufactured by Mitsui Chemicals, Petrite manufactured by Mikuni Chemicals, Neopolymer manufactured by JX Nippon Oil & Energy, Petcol manufactured by Tosoh, and Petrotac.

Furthermore, modified petroleum resins obtained by modifying petroleum resins made of the _C9 fraction are preferably used in the present invention as resins that have both high adhesion and adhesion durability. Examples of modified petroleum resins include _C9 -based petroleum resins modified with unsaturated alicyclic compounds, _C9 -based petroleum resins modified with compounds having hydroxyl groups, and _C9 -based petroleum resins modified with unsaturated carboxylic acid compounds. Preferred unsaturated alicyclic compounds include cyclopentadiene and methylcyclopentadiene, and examples of Diels-Alder reaction products of alkylcyclopentadiene include dicyclopentadiene, cyclopentadiene/methylcyclopentadiene codimers, and tricyclopentadiene, with dicyclopentadiene being particularly preferred. Dicyclopentadiene-modified _C9 -based petroleum resins can be obtained by thermal polymerization or the like in the presence of both dicyclopentadiene and the _C9 fraction. An example of a dicyclopentadiene-modified _C9 petroleum resin is Neopolymer 130S manufactured by JX Nippon Oil & Energy Corporation.

Examples of compounds having a hydroxyl group include alcohol compounds and phenol compounds. Specific examples of alcohol compounds include alcohol compounds having a double bond, such as allyl alcohol and 2-butene-1,4-diol. Examples of phenol compounds that can be used include alkylphenols such as phenol, cresol, xylenol, p-t-butylphenol, p-octylphenol, and p-nonylphenol. These hydroxyl group-containing compounds may be used alone or in combination of two or more.

Hydroxyl-containing _C9 -based petroleum resins can also be produced by a method of thermally polymerizing a petroleum fraction and an alkyl (meth)acrylate ester, etc., to introduce an ester group into the petroleum resin, and then reducing the ester group, or by hydrating a double bond remaining or introduced into the petroleum resin. As the hydroxyl-containing _C9 -based petroleum resin, those obtained by various methods as described above can be used, but from the viewpoints of performance and production, it is preferable to use phenol-modified petroleum resins, etc., which are obtained by cationic polymerization of a _C9 fraction in the presence of phenol, are easy to modify, and are low-cost. An example of a phenol-modified _C9 -based petroleum resin is Neopolymer-E-130 manufactured by JX Nippon Oil & Energy.

Furthermore, as the _C9 petroleum resin modified with an unsaturated carboxylic acid compound, a _C9 petroleum resin modified with an ethylenically unsaturated carboxylic acid can be used. Representative examples of such ethylenically unsaturated carboxylic acids include maleic acid (anhydride), fumaric acid, itaconic acid, tetrahydrophthalic acid (anhydride), (meth)acrylic acid, and citraconic acid. The unsaturated carboxylic acid modified _C9 petroleum resin can be obtained by thermally polymerizing a _C9 petroleum resin and an ethylenically unsaturated carboxylic acid. In the present invention, maleic acid modified _C9 petroleum resin is preferred.

An example of the unsaturated carboxylic acid modified _C9 petroleum resin is Neopolymer 160 manufactured by JX Nippon Oil & Energy. In addition, a copolymer resin of a _C5 fraction and a _C9 fraction obtained by thermal decomposition of naphtha can be suitably used. The _C9 fraction is not particularly limited, but is preferably a _C9 fraction obtained by thermal decomposition of naphtha. Specific examples include TS30, TS30-DL, TS35, TS35-DL, etc., of the Struktol series manufactured by SCHILL & SEILACHER.

Examples of the phenolic resin include alkylphenol formaldehyde resin and its rosin modified product, alkylphenol acetylene resin, modified alkylphenol resin, terpene phenol resin, etc., and specifically, a novolac alkylphenol resin under the trade name of Hitanol 1502 (manufactured by Hitachi Chemical Co., Ltd.) and a p-t-butylphenol acetylene resin under the trade name of Collesin (manufactured by BASF Corporation) can be mentioned. Examples of the coal-based resin include coumarone indene resin, and examples of the xylene-based resin include xylene formaldehyde resin. In addition, polybutene can also be used as a resin having tackifying properties. Among these resins, from the viewpoint of adhesion and adhesion durability, copolymer resins of _C5 fraction and _C9 fraction, aromatic petroleum resins obtained by (co)polymerizing _C9 fraction, phenolic resins, and coumarone indene resins are preferred.

These resins preferably have a softening point of 200°C or less (measurement method: ASTM E28-58-T), and more preferably in the range of 80 to 150°C. If the softening point exceeds 200°C, processability may deteriorate, and if it is less than 80°C, adhesive performance may be poor. From these viewpoints, the softening point is more preferably in the range of 90 to 120°C. The above resins may be used alone or in a mixture of two or more types.

The amount of at least one resin selected from the above rosin-based resin, terpene-based resin, petroleum-based resin, phenol-based resin, coal-based resin, and xylene-based resin used for the purpose of adjusting the adhesiveness is preferably 0.05 to 20% by mass, and more preferably 0.05 to 10% by mass, based on the total amount of the shaft, in order to further exert the effects of the present invention.

In addition to the above-mentioned polypropylene-based resins, and in addition to the above-mentioned resins used for adjusting the adhesiveness, optional components such as heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents, antiblocking agents, sealability improvers, release agents (e.g., stearic acid, silicone oil, etc.), lubricants such as polyethylene wax, colorants, pigments, inorganic fillers (e.g., alumina, talc, calcium carbonate, mica, varastenit, clay, etc.), foaming agents (organic, inorganic), antibacterial agents (e.g., imidazole-based, phenol-based, silver, etc.), and flame retardants (e.g., hydrated metal compounds, red phosphorus, ammonium polyphosphate, antimony compounds, silicone, etc.) may be included in appropriate amounts as desired, within the scope that does not impair the effects of the present invention. In addition, the shaft material may further contain alkylsulfonic acid phenyl esters and cyclohexanedicarboxylate esters. By including alkylsulfonic acid phenyl ester and cyclohexanedicarboxylic acid ester in the shaft, it is possible to erase handwriting without damaging the paper surface or blurring the printed characters. The pen can be manufactured by methods such as extrusion molding and injection molding using the above-mentioned polypropylene resin.

When durability is to be imparted, in order to achieve the effects of the present invention, the tensile modulus (JIS K 7161:2014-1) must be 70 MPa or more, and is preferably 80 to 5000 MPa. If this tensile modulus is less than 70 MPa, the effects of the present invention cannot be achieved, which is undesirable. To achieve a tensile modulus of 70 MPa or more, the type and amount of polypropylene resin used, the types of other resins, and their contents can be suitably combined to adjust the modulus.

More preferably, in order to further exert the effects of the present invention and reduce the sense of resistance, the permanent elongation (JIS K6273:2006) of the cover member is 50% or more, and particularly preferably 50 to 100%. The "permanent elongation" defined in the present invention refers to a test piece that is stretched to twice its original length, held at 23°C for 6 hours, and then the stress is removed. The value (%) is the elongated length divided by the length before stretching.

In this embodiment, the refill is a mechanical pencil refill 40, but this is not limiting, and the refill may be, for example, a ballpoint pen refill. In addition, multiple refills may be formed by mixing, for example, mechanical pencil refills 40 and ballpoint pen refills. In addition, the refill may be combined not only with a thermochromic writing instrument refill, but also with a non-thermochromic writing instrument refill.

In this embodiment, three mechanical pencil refills 40 are stored, but this number is not limited, and two or four or more may be stored as long as the number is physically capable of being stored.

10. Thermochromic writing implements
11 Cover member 11A Knock button locking edge 11B Cylindrical portion 11C Protrusion 11D Inclined surface 11E Flange portion 11F Rib-shaped protrusion 11G Through hole 11H Recess 11I Connection surface 11J Ceiling portion 20 Shaft tube 21 Rear tube 21A Slide groove 21B Mounting portion 21C Fitting portion 21D Inclined portion 21E Slit 22 Front tube 22A Tip opening 23 Middle tube 23A Guide portion 23B Guide hole 23C Knock spring tip locking edge 23D Rear connection portion 23E Front connection portion 23F Intermediate flange portion 23G Support protrusion 30 Rotor 31 Cam groove 31A Rear end portion 31B Central portion 31C Tip portion 31D Release portion 31E Rear end inclined edge 31F Tip inclined edge 31G Locking edge 31H First extension edge 31I Guide edge 31J, second extension edge 31K, release inclined edge 31M, tip narrow portion 31L, left edge 31R, right edge 32, support hole 33, front member 34, rear member 40, mechanical pencil refill 41, lead case 41A, inner tube 41B, outer tube 42, joint 43, covering tube 43A, chuck spring tip locking edge 44, tip member 44A, tip step portion 44B, expanded diameter chamber 45, protective member 46, lead gripping mechanism 46A, pressure piece 46B, chuck spring 46C, chuck 46D, expanded portion 46E, fastener 46F, chuck spring rear end locking edge 50, knock rod
51 Knock button 51A Clip 51B Connection protrusion 52 Outer cylinder pressing portion 52A Slide portion 52B Press-fit portion 52C Connection portion 52D Flange portion 52E Slide protrusion 52F Wing-shaped protrusion 52G Notch portion 52H Knock spring rear end locking edge 52I Outwardly inclined surface 53 Inner cylinder pressing portion 53A Connection portion 53B Insertion portion 53C Abutment portion 53D Raised portion 53E Shoulder portion 53F Inwardly inclined surface 60 Friction member 70 Writing lead

Claims (1)

The invention described herein.

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