Thermochromic writing instruments

Abstract

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

Description

Technical Field

[0001] The present invention relates to a thermochromic writing instrument.

Background Art

[0002] Conventionally, there has been provided a thermochromic writing instrument in which a refill is housed inside a barrel, and the tip of any one of the refills is fed out from the tip of the barrel by a predetermined feeding operation (see Patent Document 1 and Patent Document 2). The thermochromic writing instruments disclosed in Patent Documents 1 and 2 are provided with an erasing member for changing or erasing the writing by frictional heat at the rear part of the barrel, and a crown or a cover member for preventing dirt on the erasing member is provided at the rear end of the barrel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, the crown cannot be removed from the barrel unless an operation is performed in the radial rotation direction and then the direction is changed to perform a pulling operation in the axial direction. Further, in Patent Document 2, the cover member can be removed from the barrel by a pulling operation only in the axial direction, but there is a risk that it may be difficult to remove if the member dimensions result in a strong fitting force. Therefore, a thermochromic writing instrument is provided that can easily remove a cover member that covers a friction member for changing the writing of the thermochromic writing instrument by frictional heat.

Means for Solving the Problems

[0005] After diligent development, the following invention has been realized: A thermochromic writing instrument characterized by having a friction member capable of changing the color of writing on paper at the end of the barrel, a cover member attached to the end of the barrel to cover and protect the friction member, at least one projection and an inclined surface provided on the inner circumferential surface of the cover member, and fitting portions corresponding to the number of projections and an inclined portion that can come into contact with the inclined surface formed on the outer circumferential surface of the mounting portion of the cover member at the end of the barrel.

[0006] Furthermore, the inclined surface is formed in a direction of decreasing diameter from the front to the rear, and in a fitted state where the projection of the cover member and the fitting portion of the shaft cylinder overcome each other, the inclined surface moves along the inclined portion by rotating the cover member and the shaft cylinder relative to each other, thereby allowing the cover member and the shaft cylinder to be removed.

[0007] Furthermore, the cover member is characterized by having two or more rib-like protrusions formed in the axial direction on its outer circumferential surface.

[0008] Furthermore, the force required to remove the cover member from the shaft cylinder 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.

[0009] Furthermore, the barrel comprises a front cylinder forming the axial end, a rear cylinder forming the axial rear end and separable from the front cylinder, and having a plurality of sliding grooves formed in the rear cylinder along the axial direction, the same number of refills as the plurality of sliding grooves housed inside the barrel, a knock rod connected to the rear end of each of the plurality of refills and movable along the sliding grooves, a sliding projection 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 disposed at the axial center of the barrel. The device is provided with a rotor that guides the movement of the knock rod and rotates circumferentially in conjunction with the movement of the knock rod, and cam grooves formed on the surface of the rotor corresponding to each of the plurality of knock rods, having a groove width that allows the sliding projection to move, and on one of the side edges of the cam groove a tip inclined edge that is inclined toward the other side edge of the cam groove and toward the tip in the axial direction, and on the other side edge a projection that is located toward the rear end in the axial direction than the tip inclined edge and extends toward the one side edge and engages the sliding projection A locking edge is provided to stop the sliding projection, and the cam groove is provided with a release portion that allows the sliding projection to move from the locking position where the sliding projection is locked to the locking edge to one side edge and towards 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 in the axial direction, a guide edge that is continuous with the first extension edge and extends toward one side edge, a second extension edge that is continuous with the locking edge and extends opposite to the first extension edge, and a second extension edge that is continuous with the second extension edge and extends toward one side edge and towards the tip in the axial direction The other side edge is provided with a rear end inclined edge that is inclined toward the one side edge and toward the axial end when the other sliding projection is moved toward the axial end when one sliding projection is in the locking position and the other sliding projection is in the standby position located toward the rear end of the cam groove, and the guide edge is inclined toward the other side edge at its rear end, and the biasing force of the knock spring guides the movement of the sliding projection toward the other side edge and toward the axial rear end,With the front barrel removed from the rear barrel, all knocking rods are operated, and when all knocking rods become locked inside the rear barrel, this mechanism allows for the release of that locked state. [Effects of the Invention]

[0010] With this invention, when removing the cover member from the shaft cylinder, the cover member and the shaft cylinder rotate relative to each other, causing the inclined surface inside the cover member to ride up onto the inclined portion on the outside of the shaft cylinder, making it easy to remove with little force. In particular, the cover member can be easily removed by people of all ages and genders who generally have little strength. [Brief explanation of the drawing]

[0011] [Figure 1] (A) Front view, (B) Right side view, (C) Rear view, (D) Bottom view, and (E) Top view of the thermochromic writing instrument according to this embodiment. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1(D). [Figure 3] The outer cylinder pressing portion of the knock rod is shown in (A) perspective view, (B) front view, (C) right side view, (D) rear view, (E) bottom view, (F) top view, and (G)(E) III-III cross-sectional view. [Figure 4] The inner cylinder pressing portion of the knock rod is shown in (A) perspective view, (B) front view, (C) right side view, (D) rear view, (E) bottom view, (F) top view, and (G) cross-sectional view IV-IV of (E). [Figure 5] The combined state of the outer cylinder pressing portion and inner cylinder pressing portion of the knock rod is shown in (A) perspective view, (B) front view, (C) right side view, (D) rear view, (E) bottom view, (F) top view, and (G) VV cross-sectional view of (E). [Figure 6] The rotor is shown in (A) front view, (B) right side view, (C) rear view, (D) bottom view, (E) top view, and (F)(D) VI-VI section view. [Figure 7] This is a diagram illustrating the cam operation in a rotor. [Figure 8] This is a diagram illustrating the cam operation in a rotor. [Figure 9]From the same perspective as the cross-sectional view shown in FIG. 2, (A) the state where the front cylinder is removed from the rear cylinder, (B) the fully extended state, and (C) the state where the fully extended state is released are shown respectively. [Figure 10] It is a cam operation diagram of the rotor. [Figure 11] It is a cam operation diagram of the rotor. [Figure 12] It is a rear perspective view showing the state where the cover member is removed from the shaft cylinder. [Figure 13] It shows the part drawing of the cover member, and is shown in (A) a perspective view from the front, (B) a left side view, (C) a plan view, (D) a front view, (E) a longitudinal sectional view of (D), (F) a perspective view from the rear, and (G) a right side view.

Mode for Carrying Out the Invention

[0012] This embodiment will be described while referring to the drawings. In the following description, the "tip side" refers to one side in the axial direction of the thermochromic writing instrument 10 that faces the front cylinder 22 to be described later, and the "rear end side" refers to the other side that faces the rear cylinder 21 to be described later. Also, the direction toward the tip side is referred to as "front", and the opposite direction is referred to as "rear". And the movement forward is referred to as "advance", and the movement backward is referred to as "retreat".

[0013] In addition, the "color change" in the present invention includes the case of "decoloring" using the above-mentioned thermochromic ink, and also includes erasing the drawn lines, characters, etc. written with an eraser such as a rubber. Therefore, the present invention is also applicable to any writing instrument that erases the drawn lines written using a friction member.

[0014] FIG. 1 shows the appearance of the thermochromic writing instrument 10 of this embodiment (FIGS. 1(A) to (E)). Also, FIG. 2 shows the thermochromic writing instrument 10 of this embodiment as a cross-sectional view taken along line II-II in FIG. 1(D). Note that while Figures 1(A) to (C) and Figure 2 show the thermochromic writing instrument 10 in a horizontal position, the "front," "right side," "back," "bottom," and "top" views are based on the position of the thermochromic writing instrument 10 in a vertical position. This positional relationship is the same below.

[0015] The thermochromic writing instrument 10 of this embodiment houses three mechanical pencil refills 40 (see Figure 2) inside the barrel 20. In Figure 2, only two mechanical pencil refills 40 are shown: one located on the front side and shown in cross-section, and another located on its left side. However, there is also a mechanical pencil refill 40 located on the right side, which is not shown.

[0016] With respect to 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 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."

[0017] The outermost barrel 20 of the thermochromic writing instrument 10 in this embodiment consists of a front barrel 22 that forms the axial front end, a rear barrel 21 that forms the axial rear end 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.

[0018] The rear cylinder 21 has sliding grooves 21A formed along the axial direction, corresponding 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 cylinder 21. The tip edge of this cover member 11 is a knock button locking edge 11A (see Figure 2) to which the rear end of the knock button 51, which is part of the knock rod 50, abuts. On the other hand, the tip portion of the front cylinder 22 tapers in diameter, and at its very tip is a tip opening 22A (see Figure 2) from which the tip of the mechanical pencil refill 40 can protrude.

[0019] The middle cylinder 23 consists of a roughly cylindrical guide portion 23A that is inserted into the rear cylinder 21 and guides the movement of each mechanical pencil refill 40, a rear connecting portion 23D located in front of it and pressed against the inner surface of the rear cylinder 21, a front connecting portion 23E located further in front of that and screwed into the inner surface of the front cylinder 22, and an intermediate flange portion 23F that defines the boundary between the rear connecting portion 23D and the front connecting portion 23E and is visible from the outside.

[0020] Furthermore, a support projection 23G for supporting the rotor 30, which will be described later, is formed at the rear end of the central cylinder 23. A support hole 32 is formed at the tip of the rotor 30, into which this support projection 23G is loosely fitted.

[0021] The guide portion 23A of the inner cylinder 23 has a guide hole 23B through which each mechanical pencil refill 40 is movably inserted. The rear edge of this guide hole 23B is the tip locking edge 23C of the knock spring. Between this tip locking edge 23C of the knock spring and the rear end locking edge 52H of the knock spring, which is part of the knock rod 50, a knock spring (not shown) is interposed, which is externally fitted to the rear end portion of the mechanical pencil refill 40. The knock spring (not shown) constantly biases the knock rod 50 backward relative to the inner cylinder 23.

[0022] 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 cylinder 41A that directly houses the writing lead 70 and an outer cylinder 41B that houses the inner cylinder 41A. The inner cylinder 41A and the outer cylinder 41B are made of a transparent or translucent resin that allows the interior to be seen, and the material used is, for example, polypropylene or polyethylene. The hues of writing on paper with each writing lead 70 housed in the mechanical pencil refill 40 are at least two red and orange, and the red light has a wavelength of 620 nm to less than 750 nm, and the orange light has a wavelength of 590 nm to less than 620 nm, so that the degree to which the written characters etc. are hidden by the red-based film sheet can be adjusted.

[0023] A lead-holding mechanism 46 for gripping the writing lead 70 is connected to the tip of the inner cylinder 41A. The lead-holding mechanism 46 comprises a pressing piece 46A whose rear end is directly press-fitted into the tip of the inner cylinder 41A, a chuck 46C fixed to the tip of the pressing piece 46A and directly involved in dispensing the writing lead 70, and a short cylindrical clamping device 46E fitted onto the outer circumference of the tip of the chuck 46C.

[0024] The front portion of the pressing die 46A that is pressed into the inner cylinder 41A is a flange-shaped, enlarged rear end locking edge 46F of the chuck spring, and the tip of the inner cylinder 41A is in contact with the rear end surface of this rear end locking edge 46F.

[0025] The chuck 46C is made of a metal such as brass, and its tip is an expanded section 46D that is roughly bell-shaped. This expanded section 46D is divided into multiple radial sections and is plastically deformed to expand radially outward. When the fastener 46E is fitted onto the expanded section 46D, the expanded section 46D is tightened and its expansion is prevented.

[0026] A covering cylinder 43 is connected to the tip of the outer cylinder 41B via a joint 42, covering the part of the core gripping mechanism 46 other than the expanding portion 46D. Approximately in the middle of the covering cylinder 43, the inner diameter narrows to form a stepped portion, which serves as the chuck spring tip locking edge 43A.

[0027] A chuck spring 46B is interposed between the chuck spring tip locking edge 43A and the aforementioned chuck spring rear end locking edge 46F, which constantly biases the inner cylinder 41A to the rear. Furthermore, a substantially cylindrical tip member 44, which gradually decreases in diameter towards the front, is connected to the tip of this covering cylinder 43.

[0028] A stepped tip portion 44A, which is a stepped portion with a reduced inner diameter, is formed approximately in the middle of the tip member 44, slightly forward of the expanding portion 46D of the chuck 46C. The space in front of this stepped tip portion 44A is an expanding chamber 44B into which the chuck 46C can advance and expand.

[0029] In the tip member 44, the diameter further forward of the tip step portion 44A is reduced in stages, and the very tip portion is reduced to an inner diameter sufficient for the writing lead 70 to pass through. Inside the rear end of this very tip portion, a protective member 45 made of soft resin is installed to protect the writing lead 70.

[0030] The knocking rod 50 is composed of a knock button 51 that protrudes outward from the sliding groove 21A of the rear cylinder 21, an outer cylinder pressing part 52 that presses against the outer cylinder 41B, and an inner cylinder pressing part 53 that presses against the inner cylinder 41A. The knocking rod 50 is connected to the rear end of each mechanical pencil refill 40 and is movable along the sliding groove 21A.

[0031] In one of the three sets of knocking rods 50, the knock button 51 is integrally formed with the clip 51A. In Figure 2, the cross-section of the sliding projection 52E that protrudes from the outer cylinder pressing portion 52 toward the axial center is visible. Details of the other knocking rods 50 will be described later.

[0032] A rotor 30 is mounted on the rear end portion inside the rear cylinder 21, at the axis of the shaft cylinder 20. The rotor 30 is a substantially cylindrical member, and a support hole 32 is formed at its tip, into which the support projection 23G is loosely fitted, as described above. 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 rods 50 by the cam grooves 31 and rotates in the circumferential direction as the knock rods 50 move. Details of this will be described later.

[0033] Figure 3 shows the outer cylinder pressing portion 52 of the knock rod 50 in (A) perspective view, (B) front view, (C) right side view, (D) rear view, (E) bottom view, (F) top view, and (G)(E) III-III cross-sectional view, respectively.

[0034] The outer cylinder pressing portion 52 has a sliding portion 52A that slides along the cam groove 31, a press-fit portion 52B that is press-fitted into the outer cylinder 41B, and a connecting portion 52C that connects the sliding portion 52A and the press-fit portion 52B. The outer cylinder pressing portion 52 is connected to the rear end of the outer cylinder 41B by this press-fit portion 52B.

[0035] The sliding portion 52A and the connecting portion 52C are continuous without a boundary and have a long plate shape that is curved in an arc along the circumferential direction (see Figure 3(F)). Wing-shaped projections 52F are formed on both sides of the sliding portion 52A, each projecting laterally.

[0036] The wing-shaped projection 52F plays a role in supporting the side surface of the knock button 51 that contacts the outer surface of the outer cylinder pressing portion 52 while connected to the inner cylinder pressing portion 53. In addition, a sliding projection 52E that directly contacts the cam groove 31 protrudes toward the axis from the inner surface of the sliding portion 52A (see Figures 3(D), (F), and (G)).

[0037] Between the connecting portion 52C and the press-fit portion 52B, an annular flange portion 52D is formed that protrudes outward. The front end surface of this flange portion 52D is the aforementioned knock spring rear end locking edge 52H.

[0038] 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 of the tip of the notch 52G is an outward-sloping surface 52I that is inclined to decrease in thickness towards the front (see Figures 3(A), (B), (E), and (G)).

[0039] Figure 4 shows the inner cylinder pressing portion 53 of the knock rod 50 in (A) perspective view, (B) front view, (C) right side view, (D) rear view, (E) bottom view, (F) top view, and (G) cross-sectional view IV-IV of (E).

[0040] The inner cylinder pressing portion 53 has a pair of protruding connecting portions 53A involved in connecting with the knock button 51, an insertion portion 53B that is inserted into the notch portion 52G, and a contact portion 53C formed at the tip of the insertion portion 53B with a flat tip. The inner cylinder pressing portion 53 is connected to the knock button 51 by inserting the connecting projection 51B (see Figure 2) of the knock button 51 between the connecting portions 53A.

[0041] The press-fit portion 52B is narrower than the connecting portion 53A, and the stepped portion forms the shoulder portion 53E. In addition, the tip of the connecting portion 53A has a protruding raised portion 53D that extends outward.

[0042] The insertion portion 53B is the part that advances due to the knocking action and slides along the insertion portion 53B. The contact portion 53C is the part that contacts the rear end of the inner cylinder 41A due to the advancement of the insertion portion 53B caused by this knocking action. The inner surface of the tip portion of the insertion portion 53B is an inwardly inclined surface 53F that is sloped to increase in thickness toward the contact portion 53C (see Figures 4(C), (D), and (G)).

[0043] Figure 5 shows the combined state of the outer cylinder pressing portion 52 and the inner cylinder pressing portion 53 in (A) perspective view, (B) front view, (C) right side view, (D) rear view, (E) bottom view, (F) top view, and (G)(E) VV cross-sectional view, respectively.

[0044] Figure 5 shows the knock rod 50 in its 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, which is inserted into the notch portion 52G by the knocking action, moves forward, causing the inwardly inclined surface 53F to move away from the outwardly inclined surface 52I. Consequently, the shoulder portion 53E of the inner cylinder pressing portion 53 approaches the flange portion 52D.

[0045] Figure 6 shows the rotor 30 in (A) front view, (B) right side view, (C) rear view, (D) bottom view, (E) top view, and (F)(D) VI-VI cross-sectional view, respectively.

[0046] For molding purposes, the rotor 30 is formed by separately molding a front member 33 located at the front and a rear member 34 located at the rear. The rotor 30 is then formed by combining the front member 33 and the rear member 34, and as a whole it has a substantially cylindrical shape. The aforementioned support holes 32 are formed on the tip surface of the rotor 30. In addition, three cam grooves 31, the same number as the knock rods 50, are formed on the surface of the rotor 30.

[0047] The cam groove 31 has a groove width that allows the sliding projection 52E to move, and from its rear end, it is referred to as the rear end 31A, the central part 31B, the front end 31C, and the release part 31D. In the drawing, the left side edge of the cam groove 31 is referred to as the left edge 31L, and the right side edge is referred to as the right edge 31R.

[0048] The rear end portion 31A is a relatively wide portion of the cam groove 31, and a rear end inclined edge 31E is provided on its right edge 31R, which is inclined toward the left edge 31L and toward the front. This rear end inclined edge 31E is the portion that contacts the other sliding projection 52E when it is advanced while one sliding projection 52E is in a locking position (described later) and the other sliding projection 52E is in a standby position located at the rear end portion 31A. The rear end inclined edge 31E extends from its tip to the central portion 31B.

[0049] The central portion 31B is a relatively narrow groove in the cam groove 31, with the left edge 31L and the right edge 31R facing each other and extending along the axial direction. The right edge 31R extending along the axial direction in the central portion 31B bends to the right (the locking edge 31G, described later) and extends to the tip portion 31C.

[0050] The tip portion 31C is a relatively wide groove portion in the cam groove 31, and its left edge 31L is provided with a tip inclined edge 31F that slopes toward the right edge 31R and toward the front. Furthermore, on the right edge 31R of the tip portion 31C, behind the tip inclined edge 31F, there is a locking edge 31G that bends to the right at an acute angle slightly less than 90° from the tip of the right edge 31R in the central portion 31B. This locking edge 31G is used to position the sliding projection 52E in a locked position where it is locked to the locking edge 31G. The release portion 31D is reached from the tip of the tip inclined edge 31F.

[0051] The release portion 31D is a part of the cam groove 31 that allows the sliding projection 52E, which is in the locked position, to move forward of the tip inclined edge 31F and toward the left edge 31L from the locked 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.

[0052] 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 in a continuous manner with the tip inclined edge 31F.

[0053] The guide edge 31I is a portion provided on the left edge 31L of the release section 31D, and extends continuously with the first extension edge 31H toward the left edge 31L. Furthermore, the rear end of the guide edge 31I is inclined toward the right edge 31R.

[0054] 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 facing the first extension edge 31H.

[0055] The release inclined edge 31K is a portion provided on the right edge 31R of the release section 31D, and is inclined toward the left edge 31L and forward, continuous with the second extension edge 31J. The release inclined edge 31K and the guide edge 31I are opposite each other.

[0056] Furthermore, the tip of the release portion 31D, that is, the tip of the cam groove 31, is provided with a narrow tip portion 31M that is slightly narrower than the width of the sliding projection 52E. When the sliding projection 52E, which has advanced along the release portion 31D, reaches the narrow tip portion 31M, the knock button 51 comes into contact with the tip of the sliding groove 21A, stopping its forward movement.

[0057] The knocking operation of the thermochromic writing instrument 10 of this embodiment will be explained below using Figures 2 and 7 to 11. In Figures 7 and 8, and Figures 10 and 11, the position of the sliding projection 52E in the cam groove 31 is indicated by the hatched area.

[0058] In the initial state described below, the thermochromic writing instrument 10 is in a retracted state (see Figure 2). At this time, all the sliding projections 52E of the knocking rods 50 are in contact with the left edge 31L at the rear end 31A of the cam groove 31 and are in a standby position (see Figure 7(A)).

[0059] When the first knock button 51 is advanced from this standby position, the inner cylinder pressing part 53 connected to the first knock button 51 advances and comes into contact with the rear end of the inner cylinder 41A.

[0060] At this time, the pressing piece 46A connected to the tip of the inner cylinder 41A presses the covering cylinder 43 forward via the chuck spring 46B. This forward pressing force is also transmitted to the outer cylinder 41B connected via the joint 42, and as a result, the entire mechanical pencil refill 40 moves forward while compressing the knock spring (not shown).

[0061] At this time, the outer cylinder pressing portion 52 connected to the outer cylinder 41B also moves forward simultaneously, causing the sliding projection 52E to move forward along the left edge 31L of the cam groove 31 and through the central portion 31B (see Figure 7(B)).

[0062] When the knock button 51 is advanced further from its position passing through the central part 31B, the sliding projection 52E reaches the inclined tip edge 31F (see Figure 7(C)). Here, the force generated by the advancement of the sliding projection 52E presses the inclined tip edge 31F to the left, and as a reaction, a force is applied to the sliding projection 52E to the right. However, the knock button 51, which is located outside the sliding part 52A to which the sliding projection 52E belongs, moves along the sliding groove 21A of the barrel 20 (rear barrel 21) and therefore cannot move left or right.

[0063] Furthermore, since the first knock button 51 is pressed down on both sides by the wing-shaped projections 52F (see Figure 3) on both sides of the sliding portion 52A, the sliding projection 52E cannot move to the right. Therefore, the leftward pressing force on the tip inclined edge 31F causes the rotor 30 to rotate clockwise (direction of rotation viewed from the rear end; the same applies hereafter).

[0064] When the rotor 30 is rotating clockwise, and the first knock button 51 is moved forward further, the sliding projection 52E moves forward through the release section 31D and reaches the release inclined edge 31K. At this point, the force generated by the forward movement of the sliding projection 52E pushes the release inclined edge 31K to the right, and in reaction, a force is applied to the sliding projection 52E to the left. However, as mentioned above, the sliding projection 52E cannot move to the left, so the rightward pressing force on the release inclined edge 31K causes the rotor 30 to rotate counterclockwise.

[0065] When the first knock button 51 is advanced further from the state in which the rotor 30 is rotating counterclockwise, the sliding projection 52E reaches the narrow tip portion 31M (see Figure 7(D)), and as a result the knock button 51 comes into contact with the tip of the sliding groove 21A, stopping the advance of the sliding projection 52E. At this time, the thermochromic writing instrument 10 is in the state in which the mechanical pencil refill 40 protrudes the most from the tip opening 22A of the tip barrel 22.

[0066] When the pressure on the first 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 backward by the restoring force of the knock spring (not shown). Subsequently, the mechanical pencil refill 40 stops retracting when the sliding projection 52E comes into contact with the locking edge 31G (see Figure 7(E)). That is, the sliding projection 52E is in the locked position.

[0067] Therefore, in the thermochromic writing instrument 10 with the sliding projection 52E in the locked position, the writing tip of the mechanical pencil refill 40 will remain protruding at a position slightly retracted from the tip opening 22A where it protrudes the most.

[0068] When the knock button 51, which has a sliding projection 52E in a locked position, is advanced, the sliding projection 52E moves until it reaches the narrow tip portion 31M (see Figure 7(D)). At this time, the inner cylinder 41A, which is pressed forward by the contact portion 53C of the inner cylinder pressing portion 53, moves forward, and the chuck 46C is pressed forward while compressing the chuck spring 46B via the pressing piece 46A.

[0069] Then, the expanding portion 46D of the chuck 46C moves forward into the expanding chamber 44B, freeing itself from the restraint of the clamp 46E and expanding, causing the writing lead 70 to be extended forward.

[0070] In other words, the distance that the sliding projection 52E can move in the cam groove 31 from the locking edge 31G to the narrow tip portion 31M (in other words, the distance from the rear end of the sliding projection 52E to the locking edge 31G in Figure 7(D), or the distance from the tip of the sliding projection 52E to the narrow tip portion 31M in Figure 7(E)) is the distance of one knock stroke in extending the writing lead 70, and the knocking action causes the sliding projection 52E to move back and forth over this distance.

[0071] When the sliding projection 52E reaches the narrow tip portion 31M and the knock button 51 is in contact with the tip of the sliding groove 21A, releasing the pressure on one knock button 51 causes the sliding projection 52E to move along the guide edge 31I toward the right edge 31R and backward, and stops moving backward when it comes into contact with the locking edge 31G (see Figure 7(E)). That is, the sliding projection 52E is in the locked position. At the same time, the chuck 46C also retracts, and the expanding portion 46D is once again restrained by the fastener 46E.

[0072] At this time, when pressure is applied to the writing lead 70, the mechanical pencil refill 40 has room to retract until the contact portion 53C of the inner cylinder pressing portion 53 contacts the tip of the press-fit portion 52B of the outer cylinder pressing portion 52. During this retraction, the expanding portion 46D of the chuck 46C wedge-shaped into the fastener 46E, thereby transferring the writing pressure to the lead-holding force of the chuck 46C.

[0073] Therefore, since the chuck spring 46B does not need to bear the core holding force alone, the load of the chuck spring 46B only needs to be large enough (specifically about 2N) to allow the fastener 46E to fix against the chuck 46C.

[0074] When one sliding projection 52E is in the locked position, the other sliding projection 52E is in contact with the rear inclined edge 31E of the right edge 31R at the rear end 31A of the cam groove 31 because the rotor 30 has rotated clockwise relative to its original position (i.e., the position shown in Figure 7(A)) (see Figure 8(A)).

[0075] When one sliding projection 52E is in the locked position, if the knock button 51 having the other sliding projection 52E is advanced, the other sliding projection 52E presses against the rear inclined edge 31E.

[0076] Here, the force generated by the forward movement of the sliding projection 52E presses the rear inclined edge 31E to the right, and in reaction to this, a force is applied to the sliding projection 52E to the left. However, as described above, the sliding projection 52E cannot move to the left, so the rightward pressing force on the rear inclined edge 31E causes the rotor 30 to rotate counterclockwise (see Figure 8(A)).

[0077] As a result of the counterclockwise rotation of the rotor 30, the sliding projection 52E, which is in the locked position, moves from the locked edge 31G to the left edge 31L, and the locking with the locked edge 31G is released (see Figure 8(B)).

[0078] Then, the sliding projection 52E, having released its engagement with the locking edge 31G, reaches the central portion 31B, and the restoring force of the knock spring (not shown) causes the central portion 31B to retract (see Figure 8(C)). Consequently, the entire mechanical pencil refill 40 retracts, and the writing tip retracts from the tip opening 22A into the interior of the barrel 20.

[0079] Then, each knock button 51 retracts until it contacts the knock button locking edge 11A of the cover member 11, and each sliding projection 52E returns to its original standby position as shown in Figure 2.

[0080] Next, we will explain the process by which all knocking rods 50 are knocked while the front barrel 22 is removed from the rear barrel 21 (see Figure 9), and the state in which all sliding projections 52E are locked (hereinafter referred to as the "fully extended state") is released. This fully extended state (see Figure 9(B)) occurs when, in the state shown in Figure 9(A) with the front barrel 22 removed from the rear barrel 21, all knocking rods 50 are knocked simultaneously, or when a knocking rod 50 that has been knocked is held down with a finger while the other knocking rods 50 are knocked in sequence.

[0081] In the fully extended state, all sliding projections 52E are in the locked position and are locked to the locking edge 31G (see Figures 10(A) and 11(A)). In this embodiment, there are three sliding projections 52E, but the remaining one is not shown.

[0082] From this fully extended state, when the knock button 51 having the sliding projection 52E shown in Figure 10 is advanced, the sliding projection 52E moves forward through the release section 31D and reaches the release inclined edge 31K. Thereafter, as described above, as the rotor 30 rotates counterclockwise, the sliding projection 52E, which is in the locked position shown in Figure 11(A), moves from the locking edge 31G to the left edge 31L, and the locking with the locking edge 31G is released as shown in Figure 11(B). After the locking with the locking edge 31G is released, the sliding projection 52E reaches the central section 31B, and due to the restoring force of the knock spring (not shown), the central section 31B retracts (see Figure 11(C)) and is positioned at the rear end 31A, returning to the standby position. In this case, as shown in Figure 9(C), the thermochromic writing instrument 10 will be in a state where one mechanical pencil refill 40 is fully extended and the other two mechanical pencil refills 40 are released.

[0083] On the other hand, when the knock button 51 having the sliding projection 52E shown in Figure 10 is advanced from the release inclined edge 31K, the sliding projection 52E reaches the narrow tip portion 31M (see Figure 10(B)), and as a result the knock button 51 comes into contact with the tip of the sliding groove 21A, stopping the advance of the sliding projection 52E. Then, when the pressure on one knock button 51 is released while the sliding projection 52E has reached the narrow tip portion 31M and the knock button 51 is in contact with the tip of the sliding groove 21A, the restoring force of the knock spring (not shown) causes the sliding projection 52E to move along the guide edge 31I toward the right edge 31R and backward (see Figure 10(C)), and when it comes into contact with the locking edge 31G, its backward movement stops (see Figure 10(D)). That is, the sliding projection 52E is in the locked position.

[0084] When the sliding projection 52E shown in Figure 10 is in the locked position, the sliding projection 52E shown in Figure 11, which was in the locked position, returns to the standby position as described above, and the fully extended state is released. After that, as described above, the sliding projection 52E can be moved forward by pushing the knock button 51, which is in the standby position, to return the sliding projection 52E, which is in the locked position, to the standby position (see Figures 10(E) and (F)).

[0085] As described above, according to this embodiment, even when the rotor is fully extended, the fully extended state can be released by advancing the knock button 51, which is in the locked position, with the sliding projection 52E, thereby rotating the rotor 30 counterclockwise.

[0086] Furthermore, in this embodiment, since the rear end of the guide edge 31I is inclined toward the right edge 31R, when the sliding projection 52E reaches the narrow tip portion 31M and the knock button 51 is in contact with the tip of the sliding groove 21A, and the pressure on the knock button 51 is released, the restoring force of the knock spring (not shown) causes the sliding projection 52E to retract to the locking position. Therefore, according to this embodiment, by releasing the fully extended state and advancing the knock button 51 having the sliding projection 52E that has returned to the standby position, the sliding projection 52E in the locking position can be returned to the standby position.

[0087] The writing lead 70 is a solid lead with thermochromic properties that can change color due to frictional heat, and is housed within the mechanical pencil refill 40. Specifically, the writing lead 70 requires two components: (a) a thermochromic component and (b) a component that controls the amount of heat transferred to the thermochromic component. These components are described in detail below. (a) Thermochromic components The thermochromic component used in the embodiments of the present invention (hereinafter sometimes referred to as component (a) for simplicity) includes components (a1) to (a3) ​​described later, but one such component (a) has the following characteristics, having a relatively small hysteresis width (ΔH = 1 to 7°C). (1) The color changes before and after a predetermined temperature (color change point), exhibiting a decolorized state in the temperature range above the high-temperature color change point and a colored state in the temperature range below the low-temperature color change point. (2) At room temperature, only one of the aforementioned decolorization state and color development state exists. (3) When the temperature rises above the high-temperature discoloration point due to heating, or when the temperature falls below the low-temperature discoloration point due to cooling, the other state is reached, and this state is maintained as long as the temperature is maintained, but when the application of heating or cooling ceases, it returns to the state exhibited in the room temperature range.

[0088] Also, large hysteresis characteristics (ΔH B Component (a) exhibiting a temperature range of 8 to 50°C can also be used. That is, the shape of the curve plotted on the change in color intensity due to temperature changes follows a significantly different path when the temperature is increased from a temperature below the color change temperature range compared to when it is decreased from a temperature above the color change temperature range, and the colored state in the low temperature range below the complete color development temperature (t1), or the decolorized state in the high temperature range above the complete decolorization temperature (t4), can be a component that has color memory properties in a specific temperature range [temperature range between t2 and t3 (effectively a two-phase retention temperature range)]. This component may be of the heat-decolorizing type (decolorizes when heated and develops color when cooled), or it may be encapsulated in microcapsules.

[0089] In order to have only one specific state (colored state) of the color-developing and decolorizing states of component (a) exist at room temperature, and to easily change the color (decolorize) of the writing made with component (a) by friction, it is preferable that the complete decolorization temperature (t4) is 45 to 95°C and the color development start temperature (t2) is -50 to 10°C.

[0090] The reason why it is preferable for the color development state to be maintained in the room temperature range and for the color change due to friction of the writing to be facilitated by the complete decolorization temperature (t4) to be 45 to 95°C and the color development start temperature (t2) to be -50 to 10°C can be explained as follows: If heating is stopped before reaching the complete decolorization temperature (t4) after passing through the decolorization start temperature (t3) from the color development state, the phenomenon of returning to the first state occurs, and if cooling is stopped before reaching the complete color development temperature (t1) after passing through the color development start temperature (t2) from the decolorization state, the color development state is maintained. Therefore, if the complete decolorization temperature (t4) is 45°C or higher, which is above the room temperature range, the color development state will be maintained under normal use conditions, and if the color development start temperature (t2) is -50 to 10°C, which is below the room temperature range, the decolorization state will be maintained under normal use conditions. Furthermore, when erasing handwriting by friction, if the complete decolorization temperature (t4) is 95°C or lower, the frictional heat generated by several strokes of the friction material on the writing surface can sufficiently discolor the handwriting.

[0091] If the complete decolorization temperature (t4) exceeds 95°C, the frictional heat generated by friction from the friction material will not easily reach the complete decolorization temperature, making it difficult for the writing surface to change color. This can lead to an increase in the number of friction cycles or excessive frictional load, potentially damaging the writing surface. In setting the complete decolorization temperature (t4) as described above, a higher temperature is preferable for the color development state to be maintained under normal use conditions, while a lower temperature is preferable for the frictional heat generated by friction to exceed the complete decolorization temperature (t4). Therefore, the complete decolorization temperature (t4) is preferably 50 to 90°C, more preferably 60 to 80°C. Furthermore, in setting the color development start temperature (t2) as described above, a lower temperature is preferable for the decolorization state to be maintained under normal use conditions, with -50 to 5°C being preferable and -50 to 0°C being more preferable.

[0092] The hysteresis width (ΔH) of the writing lead 70 is generally in the range of 50 to 100°C, preferably 60 to 80°C.

[0093] (a1) As components, so-called leuco dyes can be used. Specifically, examples include diphenylmethane phthalides, phenylindolyl phthalides, indolyl phthalides, diphenylmethane azaphthalides, phenylindolyl azaphthalides, fluoranes, styrinoquinolines, and diazarodamine lactones. More specifically, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindole-3-yl)phthalide, 3,3-bis(1-n-butyl-2-methylindole-3-yl)phthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-[2-ethoxy-4-(N-ethylanilino)phenyl]-3-(1-ethyl-2-methyl Indole-3-yl)-4-azaphthalide, 3,6-diphenylaminofluorane, 3,6-dimethoxyfluorane, 3,6-di-n-butoxyfluorane, 2-methyl-6-(N-ethyl-Np-tolylamino)fluorane, 3-chloro-6-cyclohexylaminofluorane, 2-methyl-6-cyclohexylaminofluorane, 2-(2-chloroanilino)-6-di-n-butylaminofluorane, 2-(3-trifluoromethylanilino)-6-diethyl Minofluorane, 2-(N-methylanilino)-6-(N-ethyl-Np-tolylamino)fluorane, 1,3-dimethyl-6-diethylaminofluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-di-n-butylaminofluorane, 2-xylidino-3-methyl-6-diethylaminofluorane, 1,2-ben-6-diethylaminofluorane, 1,2-Benz-6-(N-ethyl-N-isobutylamino)fluorane, 1,2-Benz-6-(N-ethyl-N-isoamylamino)fluorane, 2-(3-methoxy-4-dodecoxystyryl)quinoline, spiro[5H-(1)benzopyrano(2,3-d)pyrimidine-5,1'(3'H)isobenzofuran]-3'-one, 2-(diethylamino)-8-(diethylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidine-5,1'(3'H)isobenzofuran]-3-one, 2-(di-n-butylamino)-8-(di-n-butylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidine-5,1'(3'H)isobenzofuran]-3-one, 2-(di-n-butylamino)-8-(diethylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidine-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)pyrimidine-5,1'(3'H)isobenzofuran]-3-one, 2-(dibutylamino)-8-(dipentylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-g)pyrimidine-5,1'(3'H)-isobenzofuran]-3-one, 3-(2-methoxy-4-dimethylaminophenyl)-3-(1-butyl-2-methylindole-3-yl)-4,5,6,7-tetrachlorophthalate 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindole-3-yl)-4,5,6,7-tetrachlorophthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-pentyl-2-methylindole-3-yl)-4,5,6,7-tetrachlorophthalide, 4,5,6,7-tetrachloro-3-[4-(dimethylamino)-2-methylphenyl]-3-(1-ethyl-2-methyl-1H-indole-3-yl)-1(3H)-iso Examples include benzofuranone, 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, quinazoline, and bisquinazoline compounds that are effective in producing fluorescent yellow to red coloration can be mentioned, such as 4-[2,6-bis(2-ethoxyphenyl)-4-pyridinyl]-N,N-dimethylbenzeneamine can be used as an example.

[0094] Examples of electron-accepting compounds for component (a2) used in embodiments of the present invention include compounds having active protons, pseudoacidic compounds (compounds that are not acids but act as acids in the composition to cause component (a1) to develop color), and compounds having electron vacancies.

[0095] Examples of compounds having active protons include not only monophenols having one phenol group, but also polyphenols having multiple phenol groups. Furthermore, compounds having substituents such as alkyl groups, aryl groups, acyl groups, alkoxycarbonyl groups, carboxyl groups and their esters or amide groups, halogen groups, etc., as well as bis-type and tris-type phenols, and phenol-aldehyde condensation resins. Metal salts of the aforementioned compounds having phenolic hydroxyl groups can also be used. More specifically, phenol, o-cresol, tertiary butylcatechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcinol, dodecyl gallate, 2,2-bis(4-hydroxyphenyl)propane, 4,4-dihydroxydiphenylsulfone, 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 Examples include 2,1-bis(4-hydroxyphenyl)n-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.

[0096] Furthermore, while the compounds having the phenolic hydroxyl group exhibit the most effective thermal color change properties, compounds selected from aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms, carboxylic acid metal salts, acidic phosphate esters and their metal salts, 1,2,3-triazoles and their derivatives can also be used.

[0097] Examples of component (a3) ​​of the reaction medium that causes the electron transfer reaction between component (a1) and component (a2) to occur reversibly in a specific temperature range include alcohols, esters, ketones, and ethers.

[0098] Preferably, the component (a3) ​​is a carboxylic acid ester compound exhibiting a ΔT value (melting point-cloud point) of 5°C to less than 50°C that can form a color-memory thermochromic composition that changes color with large hysteresis characteristics (the curve plotting the change in color intensity due to temperature changes differs when the temperature is changed from the low side to the high side and when it is changed from the high side to the low side), such as 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, or a compound containing a substituted aromatic ring in the molecule. Carboxylic acid esters containing a chlorohexyl group, esters of fatty acids having 6 or more carbon atoms and unsubstituted aromatic alcohols or phenols, 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, trimyristine, tristearin, dimyristine, and distearin can be used.

[0099] In addition, fatty acid ester compounds obtained from an odd-numbered aliphatic monohydric alcohol having 9 or more carbon atoms and an even-numbered aliphatic carboxylic acid, or fatty acid ester compounds with a total of 17 to 23 carbon atoms obtained from an n-pentyl alcohol or n-heptyl alcohol and an even-numbered aliphatic carboxylic acid having 10 to 16 carbon atoms may be used. Specifically, the 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, and myristate. Examples include n-nonyl stoolate, 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.

[0100] Furthermore, among the ketones, aliphatic ketones with a total carbon number of 10 or more are effective, and examples 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.

[0101] Furthermore, examples of arylalkyl ketones with a total carbon number of 12 to 24 include n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecanophenone, 4-n-dodecacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonylacetophenone, n-decanophenone, 4-n-octylacetophenone, and n-nonano. Examples include phenone, 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butylpropiophenone, n-heptaphenone, 4-n-pentylacetophenone, cyclohexylphenyl ketone, benzyl-n-butyl ketone, 4-n-butylacetophenone, n-hexanophenone, 4-isobutylacetophenone, 1-acetonaphthone, 2-acetonaphthone, and cyclopentylphenyl ketone.

[0102] Furthermore, as ethers, aliphatic ethers with a total of 10 or more carbon atoms are effective, and examples 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.

[0103] The mixing ratio of the three components (a1), (a2), and (a3) ​​contained in component (a) is determined by factors such as color density, color change temperature, and the type of each component. Generally, the mixing ratio that yields the desired properties is a mass ratio of component (a1):component (a2):component (a3) ​​= 1:0.1 to 50:1 to 800, and preferably, component (a1):component (a2):component (a3) ​​= 1:0.5 to 20:5 to 200. Each of these components may be used in a mixture of two or more types.

[0104] The aforementioned component (a) may be dispersed in the writing lead 70 as is, but it is preferable to use it as a thermochromic microcapsule pigment encapsulated in microcapsules (hereinafter sometimes referred to as thermochromic microcapsules). This is because the thermochromic composition can be maintained at the same composition and produce the same effects under various usage conditions.

[0105] Furthermore, by adding any dye or pigment (non-thermally color-changing) to the microcapsule pigment, it is possible to create a substance that exhibits a color change (discoloration) from one color to another.

[0106] Methods for microencapsulating component (a) include interfacial polymerization, interfacial polycondensation, in situ polymerization, liquid curing coating, phase separation from aqueous solutions, phase separation from organic solvents, melt-dispersion-cooling, air suspension coating, and spray drying, which can be appropriately selected depending on the application. Furthermore, depending on the purpose, a secondary resin coating can be applied to the surface of the microcapsules to provide durability or modify the surface properties for practical use.

[0107] The microcapsule pigment may have a circular cross-sectional shape or a non-circular cross-sectional shape. Here, the mass ratio of component (a) to the microcapsule wall film generally satisfies the range of 7:1 to 1:1, preferably 6:1 to 1:1. If the ratio of component (a) to the wall film is greater than the above range, the wall film becomes too thin, which tends to reduce resistance to pressure and heat. If the ratio of the wall film to component (a) is greater than the above range, it tends to reduce the color density and vividness during color development.

[0108] The microcapsule pigment generally satisfies practical requirements when its average particle diameter is in the range of 0.1 to 50 μm, preferably 0.3 to 30 μm, and more preferably 0.5 to 10 μm. Caution is required because if the average value of the maximum outer diameter of the microcapsules exceeds 50 μm, dispersion stability may be lacking, and if the average value of the maximum outer diameter is less than 0.1 μm, it becomes difficult to exhibit high-concentration color development. In this invention, the average particle diameter of the microcapsules is expressed as the D50 value, which is the volume-based value when the outer diameter of the particles is measured. Here, however, the average particle diameter (median diameter) was calculated based on the values ​​obtained by measuring with a laser diffraction / scattering particle size distribution analyzer LA-300 (manufactured by Horiba, Ltd.; LA-300).

[0109] (b) The component that controls the amount of heat transferred to the thermochromic component is such that the color of the entire composition changes when the aforementioned thermochromic component (a) changes color or disappears due to heat applied from the outside. At this time, by controlling the amount of heat applied to component (a), it is possible to prevent unintended discoloration or disappearance. The component that controls the amount of heat transferred to such component (a) may be referred to as component (b) below for simplicity.

[0110] Component (b) includes: (1) A device that suppresses the amount of heat generated by friction, etc., and (2) A device that absorbs heat added from the outside and suppresses the transfer of heat to component (a). In either case, the amount of heat applied to component (a) is controlled, preventing unintended discoloration or fading of component (a).

[0111] Component (b) having such a function is: (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 immiscible state with component (a) and whose melting point is lower than that of component (a3). These include (bi) and (bii). These (bi) and (bii) have at least one of the functions of (1) or (2) above, but are not limited to having only one of the functions of (1) or (2). For example, component (bi) is thought to mainly perform the function of (1) above, but also to have the function of (2). The individual components of (b) are explained below.

[0112] 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 also to improve writing performance. That is, since sucrose fatty acid esters and dextrin fatty acid esters have relatively low melting points, it is presumed that they soften during writing and absorb friction resistance. Therefore, by adding them to the composition, writing resistance is reduced and heat generation is suppressed. For example, when writing quickly with conventional thermochromic writing lead 70, the heat generated due to friction with the paper surface becomes high, causing component (a) to become transparent and the previously formed writing to fade. In contrast, in the embodiment of the present invention, by adding the ester compound, it is possible to mitigate the heat generated due to friction with the paper surface during writing, suppress the problem of writing fading due to frictional heat generated during high-speed writing, and enable fast writing.

[0113] Furthermore, it becomes possible to layer brushstrokes, making it easy to create variations in shading on the paper. Therefore, it will be useful for serious coloring book applications, such as adult coloring books, which are currently in high demand in the market.

[0114] Sucrose fatty acid esters that can be used as described above include, in particular, C 12 ~C 22 Esters with the above fatty acids as constituent fatty acids are preferred, and palmitic acid and stearic acid are more useful. Specifically, 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.).

[0115] As for dextrin fatty acid esters that can be used as described above, in particular C 14 ~C 18 Esters with the above fatty acids as constituent fatty acids are preferred, and palmitic acid, myristic acid, and stearic acid are more useful. Specifically, the Leopal (trade name) series (manufactured by Chiba Flour Milling Co., Ltd.) can be given as examples.

[0116] (bii) An endothermic phase change compound can be used as an endothermic phase change compound that always exists in a miscible 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 a miscible state with component (a) and have a melting point lower than that of component (a3). Specifically, components that can be used as component (bii) are those that have a melting point lower than that of component (a3). Specifically, examples 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, mericyl alcohol, polyethylene glycol, and polypropylene glycol. Examples of carboxylic acids include lauric acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, nonadecyl acid, eicosanoic acid, and tetracosanoic acid behenate. Examples of esters include esters with a total of 13 or more carbon atoms, consisting of a monohydric fatty acid and an aliphatic monohydric alcohol, or a monohydric alcohol having an alicyclic ring, 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, n-propyl caprate, n-heptyl caprate, n-undecyl caprate, n-lauryl caprate, and n-caprate. -Tridecyl, 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-heptyl caprylate, 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, cyclohexylmethyl 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, cyclohexyl methyl palmitate, methyl stearate, n-amyl stearate, n-heptyl stearate Butyl, 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, n-docosyl stearate, cyclohexylmethyl stearate, oleyl stearate, isostearyl stearate, cyclohexylmethyl stearate, methyl eicosanoate, n-amyl eicosanoate, n-he Butyl, n-octyl eicosanoate, n-nonyl eicosanoate, n-decyl eicosanoate, n-undecyl eicosanoate, n-tridecyl eicosanoate, n-pentadecyl eicosanoate, 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,Examples include neopentyl octylate.

[0117] Furthermore, as esters with a total of 18 or more carbon atoms consisting of an aliphatic divalent or polyvalent carboxylic acid and an aliphatic monovalent alcohol or a monovalent alcohol having an alicyclic ring, 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, Dicetyl Malonate, Di-n-Heptadecyl Malonate, Distearyl Malonate, Di-n-Nonyl Succinate, Di-n-Decyl Succinate, 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, Gluta Di-n-heptadecyl adipate, distearyl glutarate, di-n-decyl adipate, di-n-undecyl adipate, dilauryl adipate, di-n-tridecyl adipate, dimyristyl adipate, di-n-pentadecyl adipate, dicetyl adipate, di-n-heptadecyl adipate, distearyl adipate, di-n-docosyl adipate, di-n-decyl pimephosphate, di-n-undecyl pimephosphate, dilauryl pimephosphate, di-n-tridecyl pimephosphate, dimyristyl pimephosphate, di-n-pentadecyl pimephosphate, dicetyl pimephosphate, di-n- Heptadecyl, 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, dicetyl sebacate, di-n-heptadecyl sebacate, distearyl sebacate, di-n-pentadecyl suberate, dicetyl suberate, di-n-heptadecyl suberate,Examples include distearyl suberate, di-n-decyl azelaate, di-n-undecyl azelaate, dilauryl azelaate, di-n-tridecyl azelaate, dimyristyl azelaate, di-n-pentadecyl azelaate, dicetyl azelaate, di-n-heptadecyl azelaate, distearyl azelaate, di-n-octyl 1,18-octadecylmethylenedicarboxylic acid, dicyclohexyl 1,18-octadecylmethylenedicarboxylic acid, and dineopentyl 1,18-octadecylmethylenedicarboxylic acid.

[0118] Furthermore, as esters with a total of 18 or more carbon atoms consisting of aliphatic divalent or polyvalent alcohols or divalent and polyvalent alcohols and monovalent fatty acids having an alicyclic ring, ethylene glycol dicaprylate, ethylene glycol dicaprate, ethylene glycol diundecanoate, ethylene glycol dilaurate, ethylene glycol ditridecanoate, ethylene glycol dimyristate, ethylene glycol dipentadecanate, ethylene glycol dipalmitate, ethylene glycol diheptadecanate Canate ester, ethylene glycol distearate, 1,3-propanediol dicaprylate, 1,3-propanediol dicaprate, 1,3-propanediol diundecanoate, 1,3-propanediol dilaurate, 1,3-propanediol ditridecanoate, 1,3-propanediol dimyristate, 1,3-propanediol dipentadecanoate, 1,3-propanediol dipalmitate, 1,3-propanediol diheptadecanoate, 1, 3-Propanediol distearate, 1,4-Butanediol dicaprylate, 1,4-Butanediol dicaprate, 1,4-Butanediol diundecanoate, 1,4-Butanediol dilaurate, 1,4-Butanediol ditridecanoate, 1,4-Butanediol dimyristate, 1,4-Butanediol dipentadecanoate, 1,4-Butanediol dipalmitate, 1,4-Butanediol diheptadecanoate, 1,4-Butanediol distearate Esters, 1,5-pentanediol dicaprate, 1,5-pentanediol diundecanoate, 1,5-pentanediol dilaurate, 1,5-pentanediol ditridecanoate, 1,5-pentanediol dimyristate, 1,5-pentanediol dipentadecanoate, 1,5-pentanediol dipalmitate, 1,5-pentanediol diheptadecanoate, 1,5-pentanediol distearate, 1,6-hexanediol dicaprate, 1,6-Hexanediol diundecanoate, 1,6-Hexanediol dilaurate, 1,6-Hexanediol ditridecanoate, 1,6-Hexanediol dimyristate, 1,6-Hexanediol dipentadecanoate, 1,6-Hexanediol dipalmitate, 1,6-Hexanediol diheptadecanoate, 1,6-Hexanediol distearate, 1,7-Pentanediol dicaprate, 1,7-Pentanediol diundecanoate, 1,7-Pentanediol Ludilaurate, 1,7-pentanediol ditridecanoate, 1,7-pentanediol dimyristate, 1,7-pentanediol dipentadecanoate, 1,7-pentanediol dipalmitate, 1,7-pentanediol diheptadecanoate, 1,7-pentanediol distearate, 1,8-octanediol dicaprate, 1,8-octanediol diundecanoate, 1,8-octanediol dilaurate, 1,8-octanediol ditridecanoate 1,8-octanediol dimyristate, 1,8-octanediol dipentadecanoate, 1,8-octanediol dipalmitate, 1,8-octanediol diheptadecanoate, 1,8-octanediol distearate, 1,9-nonanediol dicaprate, 1,9-nonanediol diundecanoate, 1,9-nonanediol dilaurate, 1,9-nonanediol ditridecanoate, 1,9-nonanediol dimyristate, 1,9-nonanediol di Pentadecanoate, 1,9-nonanediol dipalmitate, 1,9-nonanediol diheptadecanoate, 1,9-nonanediol distearate, 1,10-decanediol dicaprylate, 1,10-decanediol dicaprate, 1,10-decanediol diundecanoate, 1,10-decanediol dilaurate, 1,10-decanediol ditridecanoate, 1,10-decanediol dimyristate, 1,10-decanediol dipentadecanoate, 1,Examples include 10-decanediol dipalmitate, 1,10-decanediol diheptadecanate, 1,10-decanediol distearate, 1,5-pentanediol distearate, 1,2,6-hexanetriol dimyristate, pentaerythritol trimyristate, pentaerythritol tetralaurate, 1,4-cyclohexanediol dimyristate, 1,4-cyclohexanediol didecyl, 1,4-cyclohexanediol dimyristate, 1,4-cyclohexanediol distearyl, 1,4-cyclohexanedimethanol dilaurate, and 1,4-cyclohexanedimethanol dimyristate.

[0119] Furthermore, examples of esters with a total of 24 or more carbon atoms, consisting of a dihydric alcohol having an aromatic ring and a monohydric fatty acid, include xylylene glycol dicaprylate, xylylene glycol dicaprate, xylylene glycol diundecanoate, xylylene glycol dilaurate, xylylene glycol ditridecanoate, xylylene glycol dimyristate, xylylene glycol dipentadecanate, xylylene glycol dipalmitate, xylylene glycol diheptadecanate, and xylylene glycol distearate.

[0120] Furthermore, as esters with a total of 15 or more carbon atoms consisting of a monohydric carboxylic acid having an aromatic ring and an aliphatic monohydric alcohol or a monohydric alcohol having an alicyclic ring, we have 3,5-hexyl dimethylbenzoate, 2-decyl methylbenzoate, 2-lauryl methylbenzoate, 2-myristyl methylbenzoate, 2-stearyl methylbenzoate, 4-tert-butylbenzoate cetyl, 4-cyclohexylbenzoate behenyl, 4-phenylbenzoate myristyl, 4-octylbenzoate lauryl, 3-ethylbenzoate stearyl, 4-isopropylbenzoate decyl, 4-benzoylbenzoate stearyl, 4-chlorobenzoate stearyl, 3-bromobenzoate myristyl, 2-chloro-4-bromobenzoate stearyl, and 3,4-diclo Examples include 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-chlorophenyl acetate, cetyl p-chlorophenyl acetate, neopentyl salicylate, stearyl 2-naphthoate, cetyl benzylate, stearyl benzylate, decyl 3-benzoylpropionate, stearyl benzoate, myristyl benzoate, cyclohexylmethyl 2-benzoylpropionate, and cyclohexylmethyl cinnamate.

[0121] Furthermore, examples of esters with a total of 14 or more carbon atoms, consisting of a monohydric 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, 4-tert-butylbenzoate phenyl, 2-methylbenzoate 4-chlorobenzyl, and 4-methoxyphenylmethyl benzoate.

[0122] Examples of esters with a total of 15 or more carbon atoms, consisting of a monohydric fatty acid and a monohydric alcohol having an aromatic ring, 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 benzylate, stearyl benzylate, benzyl caproate, benzyl palmitate, 3-phenylpropyl stearate, and phenyl 11-bromolaurate.

[0123] Examples of esters with a total of 16 or more carbon atoms, consisting of a divalent fatty acid and a monohydric alcohol having an aromatic ring, include dibenzyl sebacate and 4,4'-diphenyldicarboxylate dineopentyl.

[0124] Furthermore, component (bii) can be selected from among those listed as component (a3). That is, if one material is selected as component (a3), any material with a lower melting point can be used as component (bii). The melting point of component (bii) must be lower than the melting point of component (a3), but the difference in melting points is preferably around 3 to 70°C. If it is greater than this range, the absorption of thermal energy will begin at a temperature lower than the temperature at which decolorization begins, which may necessitate a higher proportion of component (bii) being added. If it is smaller than this range, the absorption of thermal energy by component (bii) will be small when the decolorization start temperature is reached, which may cause decolorization to begin prematurely. Being within the aforementioned range is preferable because it prevents unnecessary decolorization of the handwriting.

[0125] Furthermore, to make the effect more pronounced, the mixing ratio of component (a3) ​​and component (bii) should be (a3):component (bii) = 1:0.1 to 3 by mass, preferably (a3):component (bii) = 1:0.3 to 2. If it is smaller than this range, the amount of heat that component (bii) can absorb will be small, and it may not be possible to prevent discoloration. If it is larger than this range, the proportion of component (a) will be small, and the color intensity will tend to decrease. It is preferable to be within this range because the color intensity of the handwriting will be sufficient and unintended discoloration can be prevented.

[0126] When component (bii) is included, it is necessary that it and component (a) always exist in an immiscible state, which can be achieved by separating them with an impermeable material. Specifically, component (a) and component (bii) are separated by a resin or the like that is incompatible with both. A more preferred method is to encapsulate either component (a) or component (bii) in a microcapsule to keep them immiscible. Even more preferred is to encapsulate each of component (a) and component (bii) in a microcapsule to keep them immiscible, which is particularly preferable because it makes processing easier when forming the writing lead 70 or the water-based ink composition for writing. Furthermore, it is possible to achieve both the effect of exhibiting an endothermic effect and the effect of preventing deformation due to ambient temperature. The microcapsule containing component (bii) (hereinafter sometimes referred to as an endothermic capsule) is not particularly limited, but it is preferable that the average particle size is 0.5 to 50 μm. If the particle size is smaller than this range, the proportion of the wall material to the microcapsules tends to increase, and the proportion of component (bii) tends to decrease. If the particle size is larger than this range, the surface area of ​​the microcapsules decreases, which impairs the endothermic effect, and tends to result in poor dispersion stability and processability when used in writing ink compositions or writing leads 70. More preferably, the particle size is 1 to 30 μm, and even more preferably, 1 to 20 μm. Within this range, the endothermic effect is good, and dispersion stability and processability are good. The method for measuring the average particle size is the same as the method used for microcapsules containing component (a). Furthermore, components (bi) and (bii) can be used in combination. By combining them, the generation of frictional heat is suppressed by component (bi), and the heat generated is absorbed by component (bii), resulting in a synergistic effect.

[0127] Other additives may include antioxidants, ultraviolet absorbers, infrared absorbers, solubilizers, preservatives, or fungicides, as long as they do not affect the function. These can be arbitrarily selected from those that are conventionally known. Hindered amine compounds can also be added. Adding hindered amine compounds has the characteristic of making the afterimage of the erased writing even less visible. Therefore, it is preferable because it can satisfy the re-writing requirement without impairing the appearance of the writing surface, thereby improving 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-piperidyl sebacate, 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, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5) Mixed esterified product with undecane, mixed esterified product 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-tetramethylpiperidine-4-yl)amino)-triazine-2-yl)-4,7-diazadecane-1,10-diamine, N- Methyl-3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperezinyl)pyrrolidine-2,5-dione, 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, dimethyl succinate and A polymer of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and a 1:1 reaction product of N,N',N'',N'''-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidine-4-yl)amino)-triazine-2-yl)-4,7-diazadecane-1,10-diamine, dibutylamine·1,3-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2, Examples include the polycondensate of 2,6,6-tetramethyl-4-piperidyl)butylamine, the reaction product of bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) decandioate (1,1-dimethylethyl hydroperoxide) with octane, and the reaction product of cyclohexane with N-butyl-2,2,6,6-tetramethyl-4-piperidineamine-2,4,6-trichloro-1,3,5-triazine peroxide and 2-aminoethanol.

[0128] The thermochromic composition used in the writing lead 70 is preferably 10 to 70% by mass of the total mass of the writing lead 70. If the amount is smaller than this range, the color density tends to be lower, and if it is larger than this range, the strength of the writing lead 70 tends to decrease. Preferably, it is 10 to 50% by mass, and more preferably, 10 to 40% by mass, as this range allows for a balance between the strength of the writing lead 70 and the density of the writing lines.

[0129] Here, component (a) is particularly preferable from the viewpoint of processability and other factors to be incorporated into the thermochromic composition in a state encapsulated in microcapsules and applied to the writing lead 70. This embodiment is also preferable because the composition of the thermochromic composition is kept constant under various usage conditions, and the same effects can be achieved.

[0130] Furthermore, although the writing lead 70 is always 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 environments with relatively high temperatures, such as in summer. Using component (bii) in microencapsulated form is particularly preferable because it makes it possible to achieve both the effect of endothermic effect and the effect of preventing deformation due to ambient temperature. On the other hand, it is also possible to use component (bi) in a state where it is contained in microcapsules, but in this case the writing resistance reduction effect of component (bi) is reduced, so it is preferable that component (bi) be added directly to the composition.

[0131] From the viewpoint of strength as a writing lead 70, it is preferable that the thermochromic composition is dispersed and solidified in an excipient. The excipient is for maintaining the shape of the writing lead 70 and includes, for example, wax, gelling agent, and clay. As the wax, any conventionally known wax may be used, specifically carnauba wax, wood wax, beeswax, microcrystalline wax, montane wax, candelilla wax, low molecular weight polyethylene, and paraffin wax. Conventionally known gelling agents can be used, for example, 12-hydroxystearic acid, dibenzylidene sorbitols, tripenzylidene sorbitols, amino acid oils, and alkali metal salts of higher fatty acids. As clay minerals, bentonite and montmorillonite are examples. The above materials are used individually or in combination. Among these excipients, polyolefin wax is preferred from the viewpoint of availability and ease of handling.

[0132] Specific examples of the polyolefin wax include polyethylene, polypropylene, polybutylene, α-olefin polymers, ethylene-propylene copolymers, and ethylene-butene copolymers.

[0133] In particular, polyolefin waxes with a softening point in the range of 100°C to 130°C and a penetration degree of 0.25 or less are useful because they provide a high writing feel. Penetration degree is defined in JIS K2207 and represents the length of penetration when a needle of a specified weight is inserted vertically into polyolefin wax at a temperature of 25°C, a load of 100g, and a penetration time of 5 seconds. A penetration degree of 0.1mm is expressed as 1. Therefore, the smaller the penetration degree, the harder the polyolefin wax, and the larger the penetration degree, the softer the polyolefin wax. Among the polyolefin waxes, acid-modified polyethylene wax is particularly preferred. Acid-modified polyethylene wax has appropriate viscosity (elasticity), so it is presumed to absorb friction resistance during writing. As a result, writing resistance is reduced and the writing feel is improved.

[0134] When polyolefin wax is used as an excipient, its blending ratio is preferably 0.2 to 70% by mass relative to the total mass of the writing lead 70. If the ratio is smaller than this range, the writing lead 70 tends not to have sufficient strength, and if it is larger than this range, it tends not to have sufficient writing density. Preferably, the ratio is 0.5 to 40% by mass, and within this range, both the strength of the writing lead 70 and the density of the writing line can be achieved.

[0135] The writing lead 70 may contain various additives as needed. Examples of additives include binders, viscosity modifiers, antifungal agents, preservatives, antibacterial agents, and fragrances. Any conventionally known binder can be used, such as talc, clay, silica, calcium carbonate, barium sulfate, alumina, mica, boron nitride, potassium titanate, glass flakes, and starch, with talc and calcium carbonate being particularly desirable from a moldability standpoint. The binders are added to improve the strength and adjust the writing feel of the writing lead 70 in the embodiments of the present invention. Furthermore, any dye or pigment (non-thermally chromogenic) can be added to the writing lead 70 to cause a color change (discoloration) from one color to another.

[0136] Furthermore, when using the aforementioned hindered amine compound, it is preferable to include 0.1 to 5% by 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 include 10 to 60% by mass, preferably 20 to 50% by mass, of component (a), 30 to 70% by mass, preferably 40 to 70% by mass, of the excipient, 5 to 30% by mass, and 0.1 to 5% by mass of the hindered amine compound in the total amount of the writing lead 70. Furthermore, when the writing lead 70 is a pencil lead or a mechanical pencil lead, it is preferable to include 10 to 60% by mass, preferably 20 to 50% by mass, of component (a), 10 to 40% by mass, of the excipient, 10 to 70% by mass, preferably 20 to 60% by mass, and 0.1 to 5% by mass of the hindered amine compound in the total amount of the writing lead 70.

[0137] 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 cylinder 21. A cylindrical mounting portion 21B is formed at the rear end of the rear cylinder 21. On the outer circumferential surface of the mounting portion 21B, a fitting portion 21C that fits with and allows attachment and detachment of the cover member 11, and a substantially inverted triangular inclined portion 21D that tapers towards the rear are formed. In this embodiment, the fitting portion 21C and the inclined portion 21D are formed at three locations at equal intervals. It is preferable to form the fitting portion 21C and the inclined portion 21D at least two locations.

[0138] A friction member 60 is detachably press-fitted and locked to the inner circumferential surface of the mounting portion 21B, and a slit 21E is formed in one place that connects the outer circumferential surface and the inner circumferential surface of the mounting portion 21B in order to facilitate the attachment and detachment of the friction member 60. By making the friction member 60 detachable, it can be easily replaced even if the friction member 60 wears out due to thermal discoloration of the ink, allowing for a variety of uses.

[0139] The cover member 11 is removably fitted over the mounting portion 21B of the rear cylinder 21. By rotating the cover member 11 and the rear cylinder 21, which is the rear of the shaft cylinder 20, the inclined surface 11D on the inner surface of the cover member 11 and the inclined portion 21D come into contact and move along it, causing the projection 11C to ride up over the fitting portion 21C to the rear, resulting in a disengaged state, and the cover member 11 and the rear cylinder 21 can be separated, or removed.

[0140] It is preferable that the force required to remove the cover member 11 from the shaft cylinder 20 be smaller in the rotational direction than in the axial direction. Furthermore, 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.

[0141] The friction member 60 is press-fitted and locked into the inner surface of the mounting portion 21B, and its rear end surface is formed in a convex curved shape to facilitate the transfer of frictional heat to the writing. Examples of materials for forming the friction member 60 include rubber materials such as silicone rubber, nitrile rubber, ethylene propylene rubber, and ethylene propylene diene rubber, as well as thermoplastic elastomers such as styrene elastomers, olefin elastomers, and polyester elastomers, mixtures of two or more rubber elastomers, mixtures of rubber elastomers and synthetic resins, and commercially available erasers.

[0142] Furthermore, the friction member 60 is formed to wear down moderately so as not to damage the paper surface and not to cause smudging of printed characters. Specifically, it is preferable that the amount of Taber wear on the wear wheel CS-17 of the Taber wear tester is 10 mg or more under the wear test (ASTM D1044) specified in JIS K7204 with a load of 9.8 N and 1000 rpm.

[0143] Furthermore, it is preferable to apply an antistatic agent to the friction member 60 to prevent contamination from dust in the atmosphere and fibers on the paper surface when not in use. Preferably, the antistatic agent is a fatty acid ester of a polyhydric alcohol or a polycondensate thereof, or a sorbitan fatty acid ester, specifically decaglyceryl monostearate, pentaerythritol stearate, sorbitan monostearate, or sorbitan monooleate, added in an amount of 0.1 to 10 wt%, ideally 0.5 to 5 wt%, to prevent contamination without impairing the discoloration performance.

[0144] Figures 13(A) to (G) are component diagrams of the cover member 11. The cover member 11 consists of a cylindrical portion 11B formed in a substantially triangular cross-section, a flange portion 11E with a knock button locking edge 11A at the front of the cylindrical portion 11B, and a top portion 11J at the rear. Rib-like protrusions 11F are formed on the outer surface of the cylindrical portion 11B at locations with a large curvature. By forming two or more rib-like protrusions 11F in the axial direction, fingers or other objects can easily catch on them in the rotational direction, thus assisting in the rotation required to remove the cover member 11. A through hole 11G is formed in the center of the top portion 11J, connecting the inner and outer surfaces of the cover member 11, thus preventing suffocation even if the cover member 11 is accidentally swallowed. The inner circumferential surface of the cylindrical portion 11B has projections 11C formed in the same number as the fitting portion 21C of the rear cylinder 21, an inclined surface 11D that is inclined with respect to the axis and contacts the inclined portion 21D of the mounting portion 21B when the cover member 11 is removed by rotation, a connecting surface 11I that connects one end of the multiple inclined surfaces 11D on the front side, and a recess 11H that connects the other end on the rear side. The same number of recesses 11H and connecting surfaces 11I are formed as the number of inclined portions 21. In addition, the recesses 11H are formed on the same axis as the projections 11C. When the cover member 11 is fitted into the shaft cylinder 20, the projections 11C are in a state where they are riding up on the front of the fitting portion 21C, and the inclined portion 21D is positioned in the region surrounded by the inclined surface 11D, the recess 11H and the inclined surface 11D.

[0145] The material of the cover member 11 is a plastic material that is different from and harder than the friction member 60. Specifically, it uses 50% or more by mass of polypropylene resin. This property prevents the friction member 60 from getting dirty and also allows for the erasure of writing marks formed by thermochromic ink.

[0146] The polypropylene resins that can be used are those that form the base material of the shaft, and examples include propylene homopolymers; copolymers of propylene with small amounts of other α-olefins (e.g., ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene, etc.) (including block copolymers and random copolymers); and so on. One or more of these polypropylene resins can be used as the above polypropylene resin. The effects of the present invention can be achieved by using 50% by mass or more of the above polypropylene resin in the total amount of the shaft, and the effects of the present invention cannot be achieved if the amount of polypropylene resin is less than 50% by mass.

[0147] Examples of resins that can be used other than the polypropylene resins mentioned above include polyethylene and ionomers. These resins are preferably present in an amount of 0.5 to 30% by mass of the total shaft weight, in order to further enhance the effects of the present invention.

[0148] Furthermore, preferably, to adjust the tackiness and generate sufficient frictional heat even with light force, at least one resin selected from rosin-based resins, terpene-based resins, petroleum-based resins, phenol-based resins, coal-based resins, and xylene-based resins may be included. Among these resins, those with molecular weights of several hundred to several thousand are selected and incorporated into the polypropylene-based resin formulation, which is the main component, to impart tackiness to the shaft and further enhance the effect. Specifically, various resins such as natural resins like rosin-based resins and terpene-based resins, petroleum-based resins, phenol-based resins, coal-based resins, and xylene-based resins with molecular weights of preferably 500 to 5000, more preferably 700 to 4000, can be used.

[0149] Rosin-based resins include gum rosin, tall oil rosin, wood rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, and modified rosin such as glycerin and pentaerythritol esters. Terpene-based resins include α-pinene-based, β-pinene-based, and dipentene-based terpene resins, aromatically modified terpene resins, terpene phenol resins, and hydrogenated terpene resins. Among these resins, polymerized rosin, terpene resins, hydrogenated terpene resins, aromatically modified hydrogenated terpene resins, and terpene phenol resins are preferred from the viewpoint of further stability.

[0150] Petroleum-based resins are obtained, for example, by polymerizing a mixture of unsaturated hydrocarbons such as olefins and diolefins, which are produced as by-products along with basic petrochemical raw materials such as ethylene and propylene during the thermal decomposition of naphtha in the petrochemical industry, using a Friedel-Crafts type catalyst. Examples of such petroleum-based resins include aliphatic petroleum resins obtained by (co)polymerizing the C5 fraction obtained by the thermal decomposition of naphtha, aromatic petroleum resins obtained by (co)polymerizing the C9 fraction obtained by the thermal decomposition of naphtha, copolymerized petroleum resins obtained by copolymerizing the C5 and C9 fractions, alicyclic compound petroleum resins such as hydrogenated and dicyclopentadiene-based resins, and styrene-based resins such as styrene, substituted styrene, and copolymers of styrene with other monomers. The C5 fraction obtained by the thermal decomposition of naphtha typically includes olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, as well as diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. Aromatic petroleum resins obtained by (co)polymerizing the C9 fraction are resins polymerized from C9 aromatic compounds, with vinyltoluene and indene as the main monomers. Specific examples of the C9 fraction obtained by the thermal decomposition of naphtha include styrene congeners such as α-methylstyrene, β-methylstyrene, and γ-methylstyrene, and indene congeners such as indene and coumarone. Trademarks include Petrozine (Mitsui Chemicals), Petolite (Mikuni Chemicals), Neopolymer (JX Nippon Oil & Energy), Petol (Tosoh), and Petrotac.

[0151] Furthermore, modified petroleum resins obtained by modifying petroleum resins consisting of the C9 fraction are preferably used in the present invention as resins that achieve a high degree of both tackiness and tackiness persistence. Examples of modified petroleum resins include C9 petroleum resins modified with unsaturated alicyclic compounds, C9 petroleum resins modified with compounds having hydroxyl groups, and C9 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 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.

[0152] Furthermore, compounds containing hydroxyl groups include alcohol compounds and phenol compounds. Specific examples of alcohol compounds include, for example, allyl alcohol and 2-butene-1,4-diol, which are alcohol compounds containing double bonds. Phenolic compounds that can be used include alkylphenols such as phenol, cresol, xylenol, pt-butylphenol, p-octylphenol, and p-nonylphenol. These hydroxyl group-containing compounds may be used individually or in combination of two or more.

[0153] Hydroxyl group-containing C9 petroleum resins can also be produced by methods such as thermal polymerization of (meth)acrylate alkyl esters, etc., together with petroleum fractions to introduce ester groups into the petroleum resin, followed by reduction of the ester groups; or by retaining or introducing double bonds into the petroleum resin, followed by hydration of the double bonds. Furthermore, while hydroxyl group-containing C9 petroleum resins obtained by the various methods described above can be used, from the standpoint of performance and manufacturing, it is preferable to use phenol-modified petroleum resins. Phenolic-modified petroleum resins are obtained by cationic polymerization of C9 fractions in the presence of phenol, are easy to modify, and are inexpensive. An example of a phenol-modified C9 petroleum resin is Neopolymer-E-130 manufactured by JX Nippon Oil & Energy.

[0154] Furthermore, as a C9-based petroleum resin modified with an unsaturated carboxylic acid compound, a C9-based petroleum resin modified with an ethylenically unsaturated carboxylic acid can be used. Typical examples of such ethylenically unsaturated carboxylic acids include (anhydride) maleic acid, fumaric acid, itaconic acid, tetrahydro(anhydride) phthalic acid, (meth)acrylic acid, or citraconic acid. Unsaturated carboxylic acid-modified C9-based petroleum resin can be obtained by thermal polymerization of a C9-based petroleum resin and an ethylenically unsaturated carboxylic acid. In the present invention, maleic acid-modified C9-based petroleum resin is preferred.

[0155] Examples of unsaturated carboxylic acid-modified C9 petroleum resins include Neopolymer 160 manufactured by JX Nippon Oil & Energy. Copolymer resins of C5 and C9 fractions obtained by the thermal decomposition of naphtha can also be suitably used. While there are no particular restrictions on the C9 fraction, it is preferably obtained by the thermal decomposition of naphtha. Specifically, examples include TS30, TS30-DL, TS35, and TS35-DL from the Struktol series manufactured by Schill & Seilacher.

[0156] Examples of the aforementioned phenolic resins include alkylphenol formaldehyde resins and their rosin-modified derivatives, alkylphenol acetylene resins, modified alkylphenol resins, and terpene phenol resins. Specifically, examples include the novolac-type alkylphenol resin trade name Hitanol 1502 (manufactured by Hitachi Chemical Co., Ltd.) and the pt-butylphenol acetylene resin trade name Coresin (manufactured by BASF). Examples of coal-based resins include coumarone indene resin, and examples of xylene-based resins include xylene formaldehyde resin. Polybutene can also be used as a resin with tackifying properties. Among these resins, copolymer resins of C5 and C9 fractions, aromatic petroleum resins obtained by (co)polymerizing the C9 fraction, phenolic resins, and coumarone indene resins are preferred from the viewpoint of tackiness and tackiness retention.

[0157] These resins preferably have a softening point of 200°C (measurement method: ASTM E28-58-T) or lower, 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 below 80°C, adhesive performance may be poor. From these viewpoints, a softening point in the range of 90 to 120°C is more preferable. The above resins may be used individually or mixed together in groups of two or more.

[0158] For the purpose of adjusting these adhesive properties, the amount of at least one resin selected from the above-mentioned rosin-based resins, terpene-based resins, petroleum-based resins, phenol-based resins, coal-based resins, and xylene-based resins used in the blending is preferably 0.05 to 20% by mass, and more preferably 0.05 to 10% by mass, of the total shaft weight, in order to further exhibit the effects of the present invention.

[0159] Furthermore, in addition to the polypropylene resins mentioned above, and other resins used for adjusting tackiness, optional components such as heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents, anti-blocking agents, sealing agents, release agents (e.g., stearic acid and silicone oil), lubricants such as polyethylene wax, colorants, pigments, inorganic fillers (e.g., alumina, talc, calcium carbonate, mica, valarstenit, and clay), foaming agents (organic and inorganic), antibacterial agents (e.g., imidazole, phenol, silver, etc.), and flame retardants (e.g., hydrated metal compounds, red phosphorus, ammonium polyphosphate, antimony compounds, and silicon, etc.) may be included in appropriate amounts, as long as they do not impair the effects of the present invention. Additionally, alkylsulfonate phenyl esters and cyclohexanedicarboxylic acid esters may be further included in the shaft material. By including alkylsulfonate phenyl ester and cyclohexanedicarboxylic acid ester in the shaft, it becomes possible to erase handwriting without damaging the paper surface or causing printed characters to fade. The product can be manufactured using the above-mentioned polypropylene resin, for example, by methods such as extrusion molding or injection molding.

[0160] To impart durability, the tensile modulus (JIS K 7161:2014-1) must be 70 MPa or higher, preferably between 80 and 5000 MPa, in order to exhibit the effects of the present invention. If the tensile modulus is less than 70 MPa, the effects of the present invention cannot be exhibited, which is undesirable. The tensile modulus of this shaft can be adjusted to 70 MPa or higher by suitably combining the type of polypropylene resin used, the amount blended, other resin types, and their content.

[0161] More preferably, to further enhance the effects of the present invention and reduce resistance, the permanent elongation (JIS K6273:2006) of the cover member is set to 50% or more, and particularly preferably to 50-100%. "Permanent elongation" as defined in the present invention refers to the value (%) obtained by dividing the elongated length by the length before elongation after the test piece has been stretched to twice its original length and held at 23°C for 6 hours, and then the stress has been removed.

[0162] In this embodiment, the refill is a mechanical pencil refill 40, but it is not limited to this, and for example, the refill may be a ballpoint pen refill. Also, multiple refills may be composed by mixing, for example, mechanical pencil refills 40 and ballpoint pen refills. Furthermore, it may be a combination of refills for non-thermochromic writing instruments, not just refills for thermochromic writing instruments.

[0163] In this embodiment, three mechanical pencil refills 40 were stored, but this is not limited to this number; any number of refills that can be physically accommodated may be two or four or more. [Explanation of symbols]

[0164] 10 Thermochromic writing instruments 11 Cover member 11A Knock button locking edge 11B Cylindrical part 11C protrusion 11D slope 11E Tsubabe 11F Rib-like protrusions 11G through hole 11H recess 11I Connection surface 11J Ceiling section 20 shaft cylinder 21 Rear cylinder 21A Sliding groove 21B Mounting section 21C Mating part 21D Slope 21E Slit 22 Nozzle 22A tip opening 23 Middle tube 23A Guide section 23B Guide hole 23C Knock spring tip locking edge 23D Rear connection section 23E Front connection section 23F Intermediate flange section 23G support protrusion 30 rotors 31 Cam groove 31A Rear end 31B Central part 31C Tip 31D Release part 31E Rear end sloping edge 31F Tip sloping edge 31G Locking edge 31H First Extension Edge 31I Induction Edge 31J Second extension edge 31K Release Inclined Edge 31M Narrow tip width part 31L left edge 31R Right edge 32 Support hole 33 Front Member 34 Rear component 40 Mechanical Pencil Refills 41 Core Case 41A Inner cylinder 41B Outer Tube 42 Fittings 43 Covered tube 43A Chuck spring tip locking edge 44 Tip member 44A Tip step 44B Expansion chamber 45 Protective component 46 Lead gripping mechanism 46A Pressing die 46B Chuck Spring 46C Chuck 46D Expanding section 46E Fasteners 46F Chuck spring rear end locking edge 50 Knocking sticks 51 Knock button 51A Clip 51B Connecting protrusion 52 Outer cylinder pressing part 52A Sliding part 52B Press-fit section 52C connection part 52D Flange section 52E Sliding projection 52F Pterygoid process 52G Notch 52H Knock spring rear end locking edge 52I Outward slope 53 Inner cylinder pressing part 53A Connection 53B Insertion section 53C Contact part 53D ridge 53E Shoulder 53F Inward slope 60 Friction Member 70 writing lead

Claims

[Claim 1] A thermochromic writing instrument is provided with a friction member at the end of the barrel that can change the color of handwriting on paper, and a cover member is attached to the end of the barrel to cover and protect the friction member, The friction component has 0.1 to 10 wt% of an antistatic agent added to it. At the end of the shaft cylinder, a mounting portion is formed on the inner circumferential surface into which a friction member can be press-fitted and locked, and a slit is formed connecting the outer circumferential surface and the inner circumferential surface of the mounting portion. A barrel comprising a front cylinder forming the axial tip side, a rear cylinder forming the axial rear end side and separable from the front cylinder, and having a plurality of sliding grooves formed in the rear cylinder along the axial direction, a number of refills equal to the number of sliding grooves housed inside the barrel, a knock rod connected to the rear end of each of the plurality of refills and movable along the sliding grooves, a sliding projection protruding from the inner surface of the knock rod toward the axis of the barrel, a knock spring that biases the knock rod toward the rear end in the axial direction, a rotor positioned at the axis of the barrel, which guides the movement of the knock rod and rotates circumferentially in conjunction with the movement of the knock rod, and corresponding to each of the plurality of knock rods A thermochromic writing instrument characterized in that a groove is formed on the surface of the rotor, the groove having a width that allows the sliding projection to move, and a tip inclined edge is provided on one of the side edges of the cam groove, inclined toward the other side edge of the cam groove and toward the tip in the axial direction, and a locking edge is provided on the other side edge, located toward the rear end in the axial direction of the tip inclined edge, extending toward the one side edge, and engaging the sliding projection, and the cam groove is provided with a release portion that allows the sliding projection to move from the locked position where the sliding projection is engaged with the locking edge, toward the tip in the axial direction of the one side edge and toward the tip inclined edge.

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