Writing implement

Abstract

This writing implement includes a member and a friction body. The member includes: an end wall; a first cylinder projecting from the end wall in a first direction; and a second cylinder projecting from the end wall in a second direction opposite to the first direction. The end wall is provided with a through-hole that establishes communication between the space inside the first cylinder and the space inside the second cylinder. The friction body includes: a base part which is in contact with the end of the second cylinder in the second direction; an outer part which extends from the base part, surrounds the second cylinder, and is in contact with the end wall and the second cylinder; and an inner part which extends from the base part, is surrounded by the second cylinder, and is in contact with the end wall and the second cylinder. Thermochromic-ink Handwriting can be thermally discolored by frictional heat generated by rubbing the thermochromic-ink handwriting.

Description

stationery

[0001] FIELD OF THE INVENTION The present invention relates to stationery.

[0002] Conventionally, writing implements for writing with thermochromic ink have been known. The handwriting with the thermochromic ink is thermally discolored to transparent or another color by frictional heat generated by rubbing the ink against a friction body. The friction body is attached to the end of a member such as a barrel or a cap by, for example, two-color molding.

[0003] The shapes of the member and the friction body are being considered so that the friction body is less likely to come off the end of the member when rubbing handwriting. On the other hand, if the end of the cylindrical member is closed, it may be difficult to stabilize the position of the inner mold (core) relative to the outer mold (cavity).

[0004] One example of a problem to be solved by the present invention is to provide a stationery item that can improve the moldability of a member that can suppress separation of friction bodies.

[0005] A stationery item according to one embodiment of the present invention includes a member and a friction body. The member includes an end wall, a first tube protruding from the end wall in a first direction, and a second tube protruding from the end wall in a second direction opposite the first direction, with the end wall being provided with a through-hole connecting an interior space of the first tube with an interior space of the second tube. The friction body includes a base contacting an end of the second tube in the second direction, an outer portion extending from the base to surround the second tube and contacting the end wall and the second tube, and an inner portion extending from the base to be surrounded by the second tube and contacting the end wall and the second tube, and is capable of thermally discoloring handwritten thermochromic ink by frictional heat generated by rubbing the handwritten thermochromic ink against the friction body.

[0006] According to the present invention, for example, it is possible to improve the formability of a member capable of suppressing separation of friction bodies.

[0007] FIG. 1 is a side view showing a writing instrument according to a first embodiment. FIG. 2 is a cross-sectional view showing the writing instrument according to the first embodiment taken along line F2-F2 in FIG. 1. FIG. 3 is a cross-sectional view showing the periphery of the end of the rear barrel in the writing instrument according to the first embodiment. FIG. 4 is a perspective view showing the periphery of the end of the rear barrel in the first embodiment. FIG. 5 is a cross-sectional view showing a mold for forming the rear barrel in the first embodiment. FIG. 6 is a cross-sectional view showing a mold for forming the friction body in the first embodiment. FIG. 7 is a perspective view showing the periphery of the end of the rear barrel in the second embodiment. FIG. 8 is a cross-sectional view showing the periphery of the end of the rear barrel in the writing instrument according to the third embodiment. FIG. 9 is a cross-sectional view showing the periphery of the end of the rear barrel in the writing instrument according to the fourth embodiment. FIG. 10 is a perspective view showing the periphery of the end of the rear barrel in the writing instrument according to the fifth embodiment. FIG. 11 is a cross-sectional view showing the periphery of the end of the rear barrel in the writing instrument according to the fifth embodiment. FIG. 12 is a perspective view showing the periphery of the end of the rear barrel in the writing instrument according to the sixth embodiment. FIG. 13 is a cross-sectional view showing the periphery of the end of the rear barrel in the writing instrument according to the sixth embodiment.

[0008] (First embodiment) A first embodiment will be described below with reference to FIGS. 1 to 6. Note that in this specification, components according to the embodiment and descriptions of the components may be described using multiple expressions. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may also be identified by names different from those in this specification. Furthermore, the components may also be described using expressions different from those in this specification.

[0009] In the following description, "suppress" is defined as, for example, preventing an event, action, or influence from occurring, or reducing the severity of an event, action, or influence. Also, in the following description, "restrict" is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a predetermined range and preventing movement or rotation beyond the predetermined range.

[0010] FIG. 1 is a side view showing a thermochromic writing instrument 10 according to a first embodiment. The thermochromic writing instrument (hereinafter referred to as the writing instrument) 10 of this embodiment is, for example, a marker, and is used to create (write) handwriting such as lines, figures, and letters using thermochromic ink. The writing instrument 10 is an example of stationery. The writing instrument 10 is not limited to a marker. For example, the writing instrument 10 may be a ballpoint pen or a multi-core retractable writing instrument. Furthermore, the stationery is not limited to the writing instrument 10 and may be stationery not used for writing. For example, the stationery may be an eraser capable of discoloring or erasing handwriting made with thermochromic ink. Furthermore, the stationery may have functions other than the function of discoloring or erasing handwriting made with thermochromic ink.

[0011] FIG. 2 is a cross-sectional view of the writing instrument 10 of the first embodiment taken along line F2-F2 in FIG. 1. As shown in FIG. 2, the writing instrument 10 has a barrel 11, an ink occlusion body 12, a nib 13, and a friction body 14. The friction body 14 may also be referred to as a rubbing member. The writing instrument 10 of this embodiment is a so-called cap-type writing instrument, and further has a cap that protects the nib 13. Note that the writing instrument 10 may also be another writing instrument that can accommodate the nib 13 inside the barrel 11, such as a knock-type, side-knock-type, or rotary-type writing instrument.

[0012] The shaft 11 is formed in a substantially cylindrical shape extending along a central axis Ax. The central axis Ax is an imaginary axis located approximately at the center of the shaft 11. In the following description, the direction along the central axis Ax is defined as the axial direction, the direction perpendicular to the central axis Ax as the radial direction, and the direction around the central axis Ax as the circumferential direction.

[0013] The axial direction includes a forward direction Df and a rearward direction Db. The forward direction Df is one direction included in the axial direction and is an example of a first direction. The rearward direction Db is another direction included in the axial direction and is the opposite direction to the forward direction Df. The expressions "front" and "back" in this specification are used for convenience of explanation, with the pen tip 13 being used as the reference for "front." Therefore, the expressions "front" and "backward" in this specification do not limit orientation, position, usage mode, priority, or any other conditions.

[0014] The shaft 11 has a shaft body 21. The shaft body 21 is formed in a substantially cylindrical shape extending in the axial direction. An end 21a of the shaft body 21 in the forward direction Df is open. On the other hand, an end 21b of the shaft body 21 in the rearward direction Db is closed by a friction body 14. The shaft body 21 has a front shaft 25 and a rear shaft 26. The front shaft 25 may also be referred to as a neck shaft. The rear shaft 26 may also be referred to as a barrel shaft. The rear shaft 26 is an example of a member. The member may be another member such as a cap.

[0015] The front shaft 25 is made of, for example, synthetic resin. However, the front shaft 25 may be made of other materials. The front shaft 25 extends in the axial direction and is formed in a generally cylindrical shape with an end 25a in the forward direction Df and an end 25b in the rearward direction Db that are open. The end 25a of the front shaft 25 forms the end 21a of the shaft body 21 in the forward direction Df.

[0016] The rear axle 26 is made of a synthetic resin such as ABS resin, polycarbonate (PC) resin, polypropylene (PP) resin, polybutylene terephthalate (PBT) resin, or nylon 6,6. However, the rear axle 26 may be made of other materials. Furthermore, the material of the rear axle 26 may be the same as or different from the material of the front axle 25.

[0017] The rear axle 26 extends in the axial direction and is formed in a generally cylindrical shape with an end 26a in the forward direction Df and an end 26b in the rearward direction Db that are open. The end 26b of the rear axle 26 forms the end 21b of the shaft body 21 in the rearward direction Db and is closed by the friction body 14.

[0018] The end 25b of the front axle 25 in the rear direction Db and the end 26a of the rear axle 26 in the forward direction Df fit together. For example, the end 25b of the front axle 25 in the rear direction Db is fixed into the inside of the end 26a of the rear axle 26 in the forward direction Df by screwing or press-fitting. This forms a space 28 inside the shaft body 21 that is open at the end 21a.

[0019] The ink occlusion body 12 is accommodated in the space 28 inside the shaft body 21. The ink occlusion body 12 accommodates a thermochromic ink. The thermochromic ink is, for example, a reversible thermochromic ink. Reversible thermochromic inks include various reversible thermochromic inks, such as a thermal decolorization type that is decolorized from a colored state by heating, a color memory retention type that alternately retains the colored state or the decolorized state within a specific temperature range, and a thermal color development type that develops color from a decolorized state by heating and returns to the decolorized state by cooling from the colored state.

[0020] The reversible thermochromic ink has, for example, a reversible thermochromic microencapsulated pigment as a colorant. The reversible thermochromic microencapsulated pigment contains a reversible thermochromic composition contained in microcapsules. The reversible thermochromic composition contains at least three components: an electron-donating color-forming organic compound, an electron-accepting compound, and a reaction medium that determines the temperature at which the color-forming reaction between the electron-donating organic compound and the electron-accepting compound occurs. However, the thermochromic ink is not limited to the above examples.

[0021] The pen tip 13 is provided at the end 21a of the shaft 21 in the forward direction Df. The pen tip 13 is connected to the ink occlusion body 12 inside the shaft 21. The pen tip 13 ejects the thermochromic ink stored in the ink occlusion body 12 inside the shaft 21.

[0022] Figure 3 is a cross-sectional view showing the periphery of end 26b of rear barrel 26 in writing instrument 10 of the first embodiment. Figure 4 is a perspective view showing the periphery of end 26b of rear barrel 26 of the first embodiment. As shown in Figure 3, rear barrel 26 has an end wall 31, a main barrel 32, a rear end barrel 33, and a protrusion 34. Main barrel 32 is an example of a first barrel. Rear end barrel 33 is an example of a second barrel. Protrusion 34 is an example of a first protrusion.

[0023] In this embodiment, the end wall 31, the main barrel 32, the rear end barrel 33, and the protrusion 34 are integrally formed. However, at least one of the end wall 31, the main barrel 32, the rear end barrel 33, and the protrusion 34 may be formed as a separate part from the other parts.

[0024] The end wall 31, rear end tube 33, and protrusion 34 are provided at end 21b of shaft 21 (end 26b of rear shaft 26). Note that end 21b, 26b include not only the ends of shaft 21 and rear shaft 26 in the rear direction Db, but also the peripheries of these ends.

[0025] The end wall 31 is formed, for example, in a disk shape that is substantially perpendicular to the central axis Ax. The end wall 31 has an inner surface 31a, an outer surface 31b, and an outer peripheral surface 31c. The inner surface 31a is formed substantially flat and faces the forward direction Df. The outer surface 31b is located on the opposite side of the inner surface 31a. The outer surface 31b is formed substantially flat and faces the rearward direction Db. The inner surface 31a and the outer surface 31b may be curved surfaces or may have irregularities. The outer peripheral surface 31c is a cylindrical curved surface that extends along the central axis Ax between the inner surface 31a and the outer surface 31b and faces radially outward.

[0026] The main barrel 32 protrudes from the end wall 31 in the forward direction Df. The main barrel 32 is formed in a generally cylindrical shape extending along the central axis Ax. Specifically, the main barrel 32 has a cylindrical portion with a constant diameter and a conical cylindrical portion that extends rearward from the cylindrical portion and tapers. For example, letters, pictures, and patterns are transferred onto the main barrel 32. Furthermore, when the front axle 25 and the rear axle 26 are joined to each other by screwing, a female thread is provided on the main barrel 32. However, the main barrel 32 is not limited to this example.

[0027] The main tube 32 protrudes in the forward direction Df from the outer edge of the inner surface 31 a, so that the main tube 32 is continuous with the outer peripheral surface 31 c of the end wall 31. The end wall 31 closes the end of the substantially cylindrical main tube 32 in the rearward direction Db.

[0028] The rear end tube 33 protrudes in the rear direction Db from the end wall 31. The rear end tube 33 is formed in a generally cylindrical shape extending along the central axis Ax. The diameter of the rear end tube 33 is smaller than the diameter of the main tube 32. The rear end tube 33 has an end surface 33a, an inner peripheral surface 33b, and an outer peripheral surface 33c.

[0029] The end surface 33a is provided at the end of the rear end tube 33 in the rear direction Db. Therefore, the end surface 33a is an example of the end of the second tube in the second direction. The end surface 33a is located at the end of the shaft 11 in the rear direction Db. The end surface 33a is a substantially annular flat surface and faces the rear direction Db. The end surface 33a may also be a curved surface.

[0030] The inner circumferential surface 33b is a substantially cylindrical curved surface extending along the central axis Ax between the inner edge of the annular end face 33a and the outer surface 31b of the end wall 31. The inner circumferential surface 33b faces radially inward. In other words, the inner circumferential surface 33b faces the central axis Ax.

[0031] The outer peripheral surface 33c is located on the opposite side of the inner peripheral surface 33b. The outer peripheral surface 33c is a substantially cylindrical curved surface extending along the central axis Ax between the outer edge of the annular end face 33a and the outer surface 31b of the end wall 31. The outer peripheral surface 33c faces radially outward. The diameter of the outer peripheral surface 33c is smaller than the outer diameter of the outer surface 31b. In other words, the rear end tube 33 is spaced apart from the outer peripheral surface 31c of the end wall 31.

[0032] The protrusion 34 protrudes radially outward from the outer peripheral surface 33c of the rear end tube 33 at a position spaced from the end wall 31 in the rear direction Db. The radially outward direction is an example of a direction intersecting with the second direction. The protrusion 34 may protrude from the rear end tube 33 in a direction obliquely intersecting with the central axis Ax.

[0033] In this embodiment, the protrusion 34 protrudes from the end of the rear end tube 33 in the rear direction Db. As shown in Fig. 4, the protrusion 34 is provided around the entire circumference of the outer peripheral surface 33c around the central axis Ax. Therefore, the end (tip) of the protrusion 34 on the outer side in the radial direction is formed in a substantially annular shape. As shown in Fig. 3, the diameter of the tip of the protrusion 34 is smaller than the outer diameter of the outer surface 31b.

[0034] The protrusion 34 may be provided on a part of the outer peripheral surface 33 c about the central axis Ax. For example, a plurality of protrusions 34 may protrude from the outer peripheral surface 33 c, and the plurality of protrusions 34 may be arranged at intervals in the circumferential direction.

[0035] A through hole 35 is provided in the end wall 31. The through hole 35 is a substantially circular hole that penetrates the end wall 31 along the central axis Ax. Therefore, the through hole 35 communicates between a space 36 inside the main tube 32 and a space 37 inside the rear end tube 33. The space 36 inside the main tube 32 is included in the space 28 inside the shaft body 21.

[0036] The end wall 31 further has an inner circumferential surface 31d that forms (defines or defines) the through hole 35. The inner circumferential surface 31d is located opposite the outer circumferential surface 31c. The inner circumferential surface 31d is a substantially cylindrical curved surface that extends along the central axis Ax between the inner surface 31a and the outer surface 31b and faces radially inward.

[0037] The diameter of the inner peripheral surface 33b of the rear end tube 33 is larger than the diameter of the through-hole 35 (inner peripheral surface 31d). In other words, the rear end tube 33 is spaced apart from the through-hole 35 (inner peripheral surface 31d). In this embodiment, the rear end tube 33 is located approximately in the center between the outer peripheral surface 31c and the inner peripheral surface 31d of the end wall 31. However, the rear end tube 33 is not limited to this example.

[0038] As shown in Figure 4, two notches 38 are provided in the rear end tube 33. The notches 38 are recessed from the corner between the end surface 33a and the inner peripheral surface 33b of the rear end tube 33. The two notches 38 are arranged at equal intervals (every 180°) in the circumferential direction. The rear end tube 33 further has a concave surface 33d that forms the two notches 38.

[0039] The friction body 14 is made of a material containing an elastic synthetic resin (elastomer) such as silicone resin, SBS (styrene-butadiene-styrene copolymer) resin, SEBS (styrene-ethylene-butylene-styrene copolymer) resin, fluorine-based resin, chloroprene resin, nitrile resin, polyester-based resin, and ethylene propylene diene rubber (EPDM). The material of the friction body 14 may contain multiple elastomers. The material of the friction body 14 may also be a mixture of an elastomer and a synthetic resin with relatively low elasticity. The material of the friction body 14 is a low-wear elastic material that generates less wear debris (eraser dust) due to wear compared to highly wear-resistant elastic materials such as erasers.

[0040] In this embodiment, the friction body 14 is made of a material that allows gas to pass through. In other words, the friction body 14 has a lower gas barrier property (higher gas permeability) and allows gas to pass through more easily than the rear axle 26. Note that the material of the friction body 14 is not limited to the above examples.

[0041] 3, the friction body 14 has a head 41, an outer tubular portion 42, an inner tubular portion 43, and a flange 44. The head 41 is an example of a base portion. The outer tubular portion 42 is an example of an outer portion. The inner tubular portion 43 is an example of an inner portion. The head 41, the outer tubular portion 42, the inner tubular portion 43, and the flange 44 are integrally formed.

[0042] The head 41 is a portion of the friction body 14 that is rearward of the end surface 33a of the rear end tube 33, and is in contact with the end surface 33a of the rear end tube 33. In this specification, unless otherwise specified, contact does not necessarily mean full-surface contact, but may mean at least partial contact.

[0043] The head 41 is formed in a generally hemispherical shape that protrudes rearward in the direction Db from the end surface 33a of the rear end tube 33. Therefore, the head 41 has a generally hemispherical outer surface 41a. The outer surface 41a is exposed to the outside of the writing instrument 10 and comes into contact with the handwriting when the friction body 14 rubs the handwriting. Note that the shape of the head 41 is not limited to this example.

[0044] The outer tube portion 42 is formed in a cylindrical shape extending substantially in the forward direction Df along the central axis Ax from the head portion 41. The outer tube portion 42 surrounds the rear end tube 33. The outer tube portion 42 has an end surface 42a, an inner peripheral surface 42b, and an outer peripheral surface 42c.

[0045] The end surface 42a is provided at the end of the outer tube portion 42 in the forward direction Df. The end surface 42a is located at the end of the friction body 14 in the forward direction Df. The end surface 42a is a substantially annular flat surface facing the forward direction Df. The end surface 42a may be a curved surface. The end surface 42a contacts the outer surface 31b of the end wall 31 between the outer peripheral surface 31c of the end wall 31 and the rear end tube 33.

[0046] The inner circumferential surface 42b is a generally cylindrical curved surface extending along the central axis Ax between the inner edge of the annular end face 42a and the head 41. The inner circumferential surface 42b faces radially inward. In other words, the inner circumferential surface 42b faces the central axis Ax. The inner circumferential surface 42b contacts the outer circumferential surface 33c of the rear end tube 33.

[0047] The outer peripheral surface 42c is located on the opposite side of the inner peripheral surface 42b. The outer peripheral surface 42c is a substantially cylindrical curved surface extending along the central axis Ax between the outer edge of the annular end face 42a and the outer surface 41a of the head 41. The outer peripheral surface 42c faces radially outward and is continuous with the outer surface 41a of the head 41. The diameter of the outer peripheral surface 42c is equal to or smaller than the outer diameter of the outer surface 31b of the end wall 31.

[0048] The inner cylinder portion 43 is formed in a cylindrical shape extending substantially in the forward direction Df along the central axis Ax from the head portion 41. The inner cylinder portion 43 is surrounded by the outer cylinder portion 42. That is, the outer cylinder portion 42 and the inner cylinder portion 43 are double cylinders that are concentric (coaxial) with each other.

[0049] The inner cylindrical portion 43 is surrounded by the rear end cylinder 33. The friction body 14 may have a solid portion surrounded by the rear end cylinder 33, instead of the inner cylindrical portion 43. The inner cylindrical portion 43 has an end surface 43a, an inner peripheral surface 43b, and an outer peripheral surface 43c.

[0050] The end surface 43a is provided at the end of the inner cylinder portion 43 in the forward direction Df. The end surface 43a is a substantially annular flat surface facing the forward direction Df. The end surface 43a may be a curved surface. The end surface 43a contacts the outer surface 31b of the end wall 31 between the inner circumferential surface 31d (through hole 35) of the end wall 31 and the rear end cylinder 33.

[0051] The inner circumferential surface 43b is a substantially cylindrical curved surface extending along the central axis Ax between the inner edge of the annular end face 43a and the head 41. The inner circumferential surface 43b faces radially inward. In other words, the inner circumferential surface 43b faces the central axis Ax.

[0052] The outer peripheral surface 43c is located on the opposite side of the inner peripheral surface 43b. The outer peripheral surface 43c is a substantially cylindrical curved surface extending along the central axis Ax between the outer edge of the annular end face 43a and the head 41. The outer peripheral surface 43c faces radially outward. The inner peripheral surface 42b of the outer cylindrical portion 42 and the outer peripheral surface 43c of the inner cylindrical portion 43 face each other with a gap therebetween.

[0053] A portion of the inner cylinder portion 43 fits into the two notches 38 of the rear end cylinder 33 and comes into contact with the concave surface 33d. As a result, the concave surface 33d restricts the friction body 14 from rotating relative to the rear axle 26 around the central axis Ax.

[0054] The flange 44 protrudes radially outward from the end of the outer peripheral surface 42c in the forward direction Df. The flange 44 is provided around the entire circumference of the outer peripheral surface 42c around the central axis Ax. Therefore, the end (tip) of the flange 44 on the radially outer side is formed in a substantially annular shape. The diameter of the tip of the flange 44 is substantially equal to the outer diameter of the outer surface 31b of the end wall 31. The flange 44 may be omitted.

[0055] The friction body 14 is provided with a recess 45 and a dent 46. The recess 45 is an example of a first recess. The recess 45 is provided at the end of the inner circumferential surface 42b of the outer tube portion 42 in the rearward direction Db. The recess 45 has a shape corresponding to the protrusion 34 of the rear end tube 33 and is recessed from the inner circumferential surface 42b. In other words, the recess 45 is an annular groove provided around the entire circumference of the inner circumferential surface 42b around the central axis Ax. The protrusion 34 fits into the recess 45, thereby getting caught on the outer tube portion 42 and restricting displacement of the friction body 14 in the rearward direction Db relative to the shaft 11.

[0056] The recess 46 is provided inside the cylindrical inner tube portion 43. In the present embodiment, the recess 46 extends along the central axis Ax across the head portion 41 and the inner tube portion 43. Therefore, an end 46a of the recess 46 in the rear direction Db is spaced axially rearward from the end face 33a of the rear end tube 33.

[0057] An end 46b of the recess 46 in the forward direction Df opens to the outside of the friction body 14 at the end surface 43a of the inner cylindrical portion 43. The end 46b of the recess 46 communicates with the through-hole 35 of the end wall 31. The diameter of the recess 46 is approximately the same as the diameter of the through-hole 35. Meanwhile, the recess 46 is spaced apart from the outer surface 41a of the head portion 41. That is, the end 46a of the recess 46 in the rearward direction Db is closed.

[0058] The writing instrument 10 further includes a plug 51. The plug 51 is made of, for example, a synthetic resin. The plug 51 has a higher gas barrier property and is less likely to allow gas to pass through than the friction body 14. The plug 51 is fitted into the through-hole 35 by, for example, press-fitting, and airtightly seals the through-hole 35.

[0059] The rear axle 26 of the shaft body 21 and the friction body 14 are integrally formed by, for example, double-molding. Therefore, the outer surface 31b of the end wall 31, the end face 33a, inner peripheral surface 33b, and outer peripheral surface 33c of the rear end cylinder 33, and the protrusion 34 contact the friction body 14 with almost no gap. Note that a gap may exist between the rear axle 26 and the friction body 14.

[0060] For example, two parts formed by two-color molding are joined, bonded, or adhered to each other depending on the combination of the materials of the two parts. In this embodiment, the rear axle 26 and the friction body 14 are not joined, bonded, or adhered to each other. For example, if the rear axle 26 is made of PC resin and the friction body 14 is made of SEBS resin, the rear axle 26 and the friction body 14 are not joined, bonded, or adhered to each other.

[0061] The rear axle 26 and the friction body 14 may be joined, bonded, or adhered to each other. For example, if the rear axle 26 is made of PP resin and the friction body 14 is made of SEBS resin, the rear axle 26 and the friction body 14 are joined, bonded, or adhered to each other.

[0062] 5 is a cross-sectional view showing a mold 60 for forming the rear body 26 of the first embodiment. As shown in FIG. 5, the mold 60 for forming the rear body 26 has a core 61 and two cavities 62, 63.

[0063] The core 61 has a main pillar 61a and a pin 61b. The main pillar 61a is formed in a generally cylindrical shape extending along the central axis Ax and defines the space 36 inside the main tube 32. The pin 61b is formed in a generally cylindrical shape protruding in the rear direction Db along the central axis Ax from the end of the main pillar 61a in the rear direction Db. The pin 61b forms the through-hole 35 in the end wall 31.

[0064] The cavity 62 surrounds the main post 61 a and a part of the pin 61 b ​​via a gap. The hollow space between the main post 61 a and the cavity 62 forms the main cylinder 32.

[0065] The cavity 63 has an end surface 63a. The end surface 63a is, for example, a flat surface facing the forward direction Df and abuts against the cavity 62. The end surface 63a is spaced apart in the rearward direction Db from the main pillar 61a of the core 61. The hollow between the main pillar 61a of the core 61 and the end surface 63a of the cavity 63 forms the end wall 31.

[0066] A groove 65 and a hole 66 are provided in the cavity 63. The groove 65 and the hole 66 are recessed from the end face 63a. The groove 65 is formed in a substantially annular shape extending in the circumferential direction and forms the rear end tube 33. The hole 66 extends along the central axis Ax and is surrounded by the groove 65.

[0067] The pin 61b of the core 61 is fitted into a hole 66 of the cavity 63. The cavity 63 supports the pin 61b fitted into the hole 66. The core 61 is supported at least at two points, for example, by an end of the core 61 in the forward direction Df and the pin 61b, which is an end of the core 61 in the rearward direction Db. By supporting the pin 61b, the cavity 63 restricts the core 61 from being displaced in the radial direction or tilting relative to the cavities 62 and 63.

[0068] Two gates 67 are further provided in the cavity 63. The two gates 67 communicate with the groove 65. In this embodiment, the two gates 67 communicate with the portion of the groove 65 that forms the notch 38 of the rear end tube 33. Therefore, as shown in FIG. 4 , the rear end tube 33 has a gate mark 33e that is housed in the notch 38. The gate mark 33e protrudes from a portion of the concave surface 33d that faces radially inward. Note that the gate mark 33e may protrude from another portion of the concave surface 33d.

[0069] Material is injected from the gate 67 into the cavity of the mold 60. The material flows through the cavity of the mold 60 and fills the cavity. The core 61 is pushed radially by the flowing material. However, since the pin 61b of the core 61 is supported by the cavity 63, tilting and displacement of the core 61 can be suppressed.

[0070] In the mold 60, the gate 67 is located between the groove 65 and the hole 66. For example, the recess 46, the pin 61b, and the hole 66 may be tapered in the rear direction Db. In this case, the hole 66 can be prevented from approaching the gate 67 and the runner, which makes it easier to design the cavity 63.

[0071] 6 is a cross-sectional view showing a mold 70 for forming the friction body 14 of the first embodiment. After the rear body 26 is formed, the friction body 14 is then formed. The mold 70 for forming the friction body 14 has, for example, a core 61 and a cavity 62 for forming the rear body 26, and another cavity 71. In other words, the core 61 and the cavity 62 are used in both forming the rear body 26 and forming the friction body 14. It should be noted that the manufacture of the rear body 26 and the friction body 14 is not limited to this example.

[0072] The cavity 71 has an end surface 71a. The end surface 71a is, for example, a flat surface facing the forward direction Df and abuts against the cavity 62. A hole 75 is formed in the cavity 71. The hole 75 is recessed from the end surface 71a. The rear end tube 33 and the pin 61b are housed in the hole 75.

[0073] Material is injected into the cavity of the mold 70. The material flows through the cavity of the mold 70 and fills the cavity. The pins 61b located in the cavity of the mold 70 (holes 75 of the cavity 71) form the recesses 46 of the friction body 14. As described above, the rear body 26 and the friction body 14 are molded by two-color molding.

[0074] The method of two-color molding of the rear barrel 26 and the friction body 14 is not limited to the above example. The friction body 14 may also be molded separately from the rear barrel 26 and attached to the rear barrel 26. However, by forming the friction body 14 integrally with the rear barrel 26 by two-color molding, the friction body 14 can be easily molded, firmly attached to the rear barrel 26, and the appearance of the writing instrument 10 can be prevented from being impaired.

[0075] The writing instrument 10 forms handwriting of the thermochromic ink by ejecting the thermochromic ink from the pen tip 13. Furthermore, the friction body 14 can thermally discolor the handwriting of the thermochromic ink by frictional heat generated by rubbing the handwriting of the thermochromic ink. Note that the friction body 14 may also thermally discolor handwriting of the thermochromic ink formed by a writing instrument other than the writing instrument 10.

[0076] As shown in Fig. 3 , when the friction body 14 rubs the handwriting, the writing instrument 10 is generally held by the writer (user) in a position that is substantially perpendicular or oblique to the paper surface P on which the handwriting is formed. In this state, the friction body 14 contacts the paper surface P at the outer surface 41a of the head 41 and is moved substantially parallel to the paper surface P. Therefore, when the friction body 14 rubs the handwriting, a load acts on the head 41 of the friction body 14 in a substantially radial direction. For example, a load Ff in a lateral load direction Dh shown in Fig. 3 acts on the head 41 of the friction body 14.

[0077] 3, the lateral load direction Dh is a direction substantially perpendicular to the axial direction (the forward direction Df and the rearward direction Db). However, the direction in which the load acts on the friction body 14 that frictions the handwriting is not limited to this example.

[0078] A load Ff acts on the friction body 14 in the lateral load direction Dh due to friction, while a load Fo acts on the rear axle 26 in the opposite direction to the lateral load direction Dh due to the writer. Therefore, the load Ff acting on the friction body 14 due to friction elastically deforms the friction body 14 so as to displace it relative to the rear axle 26.

[0079] A load Ff acts on the head 41 of the friction body 14, and a load Fo acts on the rear axle 26, so that the friction body 14 elastically deforms so as to be displaced in the rotational direction Dr shown in Fig. 3. The rotational direction Dr is the direction of rotation around a rotational axis that is located between the head 41 on which the load Ff acts and the position on the shaft 11 on which the load Fo acts, and that is substantially perpendicular to the axial direction.

[0080] When friction body 14 is displaced approximately in the rotational direction Dr relative to shaft 11, a portion 42d of end surface 42a of outer tube portion 42 of friction body 14 and a portion 43d of end surface 43a of inner tube portion 43 are pressed against outer surface 31b of end wall 31. Meanwhile, another portion 42e of end surface 42a of outer tube portion 42 and another portion 43e of end surface 43a of inner tube portion 43 may be separated from outer surface 31b of end wall 31. However, as explained below, writing instrument 10 of this embodiment can prevent friction body 14 from separating from end wall 31.

[0081] For example, the rear end cylinder 33 extends in the axial direction and is fitted between the outer cylinder portion 42 and the inner cylinder portion 43. An inner peripheral surface 33b of the rear end cylinder 33 supports the inner cylinder portion 43, and an outer peripheral surface 33c of the rear end cylinder 33 supports the outer cylinder portion 42. The rear end cylinder 33 supports the friction body 14, thereby limiting displacement of the friction body 14 relative to the rear axle 26.

[0082] Furthermore, the outer surface 31b of the end wall 31 supports a portion 42d of the end face 42a of the outer cylinder portion 42 and a portion 43d of the end face 43a of the inner cylinder portion 43. The protrusion 34 supports the outer cylinder portion 42 by fitting into the recess 45. The inner circumferential surface 33b and the outer circumferential surface 33c of the rear end cylinder 33, the outer surface 31b of the end wall 31, and the protrusion 34 limit displacement of the friction body 14 in the rotational direction Dr. Therefore, the portion 42e of the end face 42a of the outer cylinder portion 42 and the portion 43e of the end face 43a of the inner cylinder portion 43 can be prevented from separating from the outer surface 31b of the end wall 31.

[0083] The protrusion 34 in this embodiment is located at the end of the rear end tube 33 in the rear direction Db, and catches on the outer tube portion 42 near the portion where the head 41 and the outer tube portion 42 are connected. Therefore, the protrusion 34 can prevent the outer tube portion 42 from expanding, and can more effectively support the outer tube portion 42.

[0084] As described above, the rear barrel 26 and the friction body 14 of this embodiment are not joined, coupled, or adhered to each other. Therefore, if the rear end tube 33 and the protrusion 34 were not provided, there would be a risk that the portion 42e of the end surface 42a of the outer barrel 42 and the portion 43e of the end surface 43a of the inner barrel 43 would separate from the outer surface 31b of the end wall 31. However, by having the rear end tube 33 and the protrusion 34, the writing instrument 10 of this embodiment can prevent the friction body 14 from separating from the rear barrel 26.

[0085] When the rear barrel 26 and the friction body 14 are joined, coupled, or adhered to each other, the outer tube portion 42 and the inner tube portion 43 are joined, coupled, or adhered to the outer surface 31b of the end wall 31. However, when the friction body 14 rubs against handwriting, the friction body 14 elastically deforms, and a load acts on the outer tube portion 42 and the inner tube portion 43 in a direction that moves them away from the outer surface 31b of the end wall 31. Repeated elastic deformation due to friction could cause the outer tube portion 42 and the inner tube portion 43 to peel off from the outer surface 31b of the end wall 31. However, the rear end tube 33 and the protrusion 34 of this embodiment prevent the friction body 14 from elastically deforming in the rotational direction Dr, thereby preventing the outer tube portion 42 and the inner tube portion 43 from peeling off from the outer surface 31b of the end wall 31.

[0086] When the friction body 14 repeatedly rubs the handwriting, the friction body 14 may wear out, depending on the material of the friction body 14 and the manner of use. As the friction body 14 wears out, the outer surface 41a of the head 41 approaches the recess 46 and the rear end tube 33. When the outer surface 41a of the head 41 reaches the recess 46, the recess 46 communicates with the outer surface 41a and is exposed to the outside. This allows the writer to realize that the friction body 14 has worn out and that it is time to replace the writing instrument 10 or the friction body 14.

[0087] The recess 46 extends beyond the end surface 33a of the rear end tube 33, and therefore appears outside before the rear end tube 33 does. Therefore, even if the friction body 14 wears, the rear end tube 33 is unlikely to scrape against the paper surface P. The friction body 14 is made of a low-wear material, which basically prevents it from wearing out. However, the friction body 14 may also be made of a material that wears.

[0088] In the writing instrument 10 according to the first embodiment described above, the rear barrel 26 has an end wall 31, a main barrel 32, and a rear end barrel 33. The main barrel 32 protrudes from the end wall 31 in the forward direction Df. The rear end barrel 33 protrudes from the end wall 31 in the rearward direction Db, which is opposite to the forward direction Df. A through-hole 35 is provided in the end wall 31, connecting a space 36 inside the main barrel 32 with a space 37 inside the rear end barrel 33. The friction body 14 has a head 41, an outer tube portion 42, and an inner tube portion 43. The head 41 contacts an end surface 33a of the rear end barrel 33 in the rearward direction Db. The outer tube portion 42 extends from the head 41 to surround the rear end barrel 33 and contact the end wall 31 and the rear end barrel 33. The inner tube portion 43 extends from the head portion 41 and is surrounded by the rear end tube 33, and is in contact with the end wall 31 and the rear end tube 33. The friction body 14 is capable of thermally discoloring the handwriting of the thermochromic ink by frictional heat generated by rubbing the handwriting of the thermochromic ink.

[0089] Generally, when the friction body 14 rubs against handwriting made of thermochromic ink, a load Ff in a lateral load direction Dh, which intersects the forward direction Df and the rearward direction Db, may act on the friction body 14 due to the friction. The load Ff elastically deforms the friction body 14 so as to displace it relative to the rear end tube 33. The outer tube portion 42 surrounds the rear end tube 33, and the inner tube portion 43 fits inside the rear end tube 33. Therefore, the inner circumferential surface 33b and the outer circumferential surface 33c of the rear end tube 33 support the outer tube portion 42 and the inner tube portion 43 in the lateral load direction Dh, thereby preventing the friction body 14 from displacing in the lateral load direction Dh relative to the rear axle 26. Meanwhile, the portion of the friction body 14 that is not supported by the rear end tube 33 may displace relative to the rear axle 26. For example, the head portion 41 of the friction body 14 may elastically deform so as to displace in the lateral load direction Dh relative to the rear axle 26. In this case, the elastically deforming head 41 pulls portions of the outer tube 42 and the inner tube 43 in a direction (rotational direction Dr) away from the end wall 31. However, the rear end tube 33 supports the outer tube 42 and the inner tube 43 even at the end of the rear end tube 33 in the rearward direction Db. Therefore, the rear end tube 33 can prevent the outer tube 42 and the inner tube 43 from separating from the end wall 31. Therefore, the writing instrument 10 of this embodiment can prevent the friction body 14 from separating from the rear barrel 26 during friction.

[0090] The rear barrel 26, which can hold the friction element 14 with the rear end tube 33, as described above can be manufactured by, for example, injection molding. If the material injected into the mold 60 causes the core 61 to tilt or displace relative to the cavities 62, 63, uneven thickness or bending may occur in the rear barrel 26, potentially affecting transfer to the rear barrel 26 or assembly of the writing instrument 10. However, in this embodiment, the space 36 inside the main barrel 32 and the space 37 inside the rear end tube 33 are connected by the through-hole 35, so the pin 61b of the core 61 can be supported by the cavity 63 through the through-hole 35. Alternatively, a portion of the cavity 63 may be supported by the core 61 through the through-hole 35. By supporting the core 61 and the cavity 63 together, the core 61 can be prevented from tilting or displaced by, for example, the injected material. Therefore, the writing instrument 10 of this embodiment can improve the moldability of the rear barrel 26, which can prevent the friction element 14 from separating.

[0091] The rear axle 26 has a protrusion 34. The protrusion 34 protrudes from the rear end tube 33 in a direction intersecting the rear direction Db at a position spaced from the end wall 31 in the rear direction Db, and fits into a recess 45 provided in the outer tube portion 42.

[0092] For example, the head 41 of the friction body 14 elastically deforms so as to be displaced in the lateral load direction Dh relative to the rear barrel 26, thereby pulling a portion of the outer tube portion 42 and the inner tube portion 43 in a direction (rotational direction Dr) away from the end wall 31. However, the protrusion 34 of the rear barrel 26 catches on the recess 45 of the outer tube portion 42, thereby preventing the outer tube portion 42 and the inner tube portion 43 from separating from the end wall 31. Therefore, the writing instrument 10 of this embodiment can prevent the friction body 14 from separating from the end wall 31 during friction.

[0093] A depression 46 is provided in the friction body 14. The depression 46 extends from the head portion 41 to the inner tube portion 43 and communicates with the through-hole 35. Depending on the material and usage of the friction body 14, the head portion 41 of the friction body 14 may wear, causing the depression 46 to be exposed to the outside. In this case, the writer can notice the wear of the friction body 14 based on the exposure of the depression 46. Because the depression 46 is provided not only in the inner tube portion 43 but also in the head portion 41, it extends beyond the end (end surface 33a) of the rear end tube 33 in the rear direction Db. Therefore, the depression 46 can be exposed before the rear end tube 33, preventing the exposed rear end tube 33 from coming into contact with, for example, the paper surface P. Furthermore, the depression 46 communicates with the through-hole 35, thereby forming the inner tube portion 43 of the friction body 14 into a cylindrical shape, thereby preventing molding defects such as sink marks and voids in the friction body 14. Furthermore, when the friction body 14 is also formed by injection molding, the common core 61 can form the through-hole 35 of the rear body 26 and the recess 46 of the friction body 14. In other words, the rear body 26 and the friction body 14 can be manufactured by two-shot molding without changing the core 61 between the process of forming the rear body 26 and the process of forming the friction body 14.

[0094] Plug 51 seals through-hole 35. Ink occlusion body 12 is disposed in space 36 inside main barrel 32. In this case, plug 51 can seal through-hole 35, thereby sealing space 36 inside main barrel 32. Therefore, plug 51 can prevent water in the ink from evaporating from ink occlusion body 12. If writing instrument 10 is a ballpoint pen, a refill can be disposed in space 36, and if barrel 21 is a cap, the nib can be disposed in space 36. Plug 51 can prevent water in the ink from evaporating from the refill or nib.

[0095] Gas can pass through the friction body 14. If the through-hole 35 were open, there is a risk that the moisture in the ink that has evaporated from the ink occlusion body 12 would pass through the through-hole 35 and the friction body 14 and be released to the outside. However, in the writing instrument 10 of this embodiment, the through-hole 35 is sealed with the plug 51, so that the moisture in the ink can be prevented from evaporating from the ink occlusion body 12.

[0096] The rear barrel 26 and the friction body 14 are integrally formed by two-color molding. Two rear barrels 26 integrally formed by two-color molding generally adhere to each other. Therefore, the writing instrument 10 of this embodiment is able to adhere the rear barrel 26 to the friction body 14, and thus is able to prevent the friction body 14 from separating from the rear barrel 26.

[0097] The rear barrel 26 is provided with a notch 38 recessed from the rear end tube 33. The friction body 14 fits into the notch 38, thereby restricting rotation of the friction body 14 relative to the rear end tube 33 around the central axis Ax of the rear end tube 33. This allows the writing instrument 10 of this embodiment to prevent the friction body 14 from being displaced relative to the rear barrel 26.

[0098] Second Embodiment A second embodiment will be described below with reference to FIG. 7. In the following description of the embodiments, components having the same functions as components already described are given the same reference numerals as the components already described, and further description may be omitted. Furthermore, components given the same reference numerals do not necessarily have all the same functions and properties, and may have different functions and properties according to each embodiment.

[0099] 7 is a perspective view showing the periphery of the end portion 26b of the rear body 26 according to the second embodiment. As shown in FIG. 7, the rear end cylinder 33 according to the second embodiment is provided with two notches 201 instead of the notch 38.

[0100] The notch 201 is recessed from the end surface 33a of the rear end tube 33 and opens to the inner circumferential surface 33b and the outer circumferential surface 33c. The two notches 201 are arranged at equal intervals (every 180°) in the circumferential direction. The notch 201 divides the protrusion 34 into two in the circumferential direction.

[0101] The rear end tube 33 has two recessed surfaces 33f and two gate marks 33g instead of the recessed surface 33d and the gate mark 33e. The two recessed surfaces 33f form two notches 201. The two gate marks 33g each protrude from the corresponding recessed surface 33f.

[0102] The gate mark 33g is accommodated in the notch 201. The gate mark 33g protrudes from a portion of the concave surface 33f facing the rear direction Db. Therefore, the gate of the cavity does not need to be provided inside the rear end tube 33 (groove 65), which makes it easier to design the cavity.

[0103] (Third Embodiment) A third embodiment will now be described with reference to Fig. 8. Fig. 8 is a cross-sectional view showing the periphery of end portion 26b of rear barrel 26 in writing instrument 10 according to the third embodiment. As shown in Fig. 8, rear barrel 26 of the third embodiment has two protrusions 301 and 302 instead of protrusion 34. Furthermore, friction body 14 is provided with two recesses 311 and 312 instead of recess 45. Protrusions 301 and 302 and recesses 311 and 312 are substantially identical to protrusion 34 and recess 45, except as described below.

[0104] The protrusion 301, like the protrusion 34, protrudes from the end of the rear end tube 33 in the rear direction Db. The protrusion 302 protrudes from the outer peripheral surface 33c of the rear end tube 33 at a position spaced apart from the ends of the rear end tube 33 in the forward direction Df and the rear direction Db. Therefore, the protrusion 302 is spaced apart from the protrusion 301.

[0105] Like the recess 45, the recess 311 is provided at the end of the inner circumferential surface 42b of the outer cylinder portion 42 in the rear direction Db. The protrusion 301 fits into the recess 311. The recess 312 is provided on the inner circumferential surface 42b at a position spaced apart from the ends of the outer cylinder portion 42 in the forward direction Df and the rear direction Db. The protrusion 302 fits into the recess 312.

[0106] The two protrusions 301, 302 are fitted into the recesses 311, 312 and are thereby caught on the outer cylinder portion 42 at two locations. As a result, the protrusions 301, 302 more effectively restrict the friction body 14 from moving in the rearward direction Db or rotating in the rotational direction Dr relative to the shaft 11.

[0107] (Fourth Embodiment) A fourth embodiment will now be described with reference to Fig. 9. Fig. 9 is a cross-sectional view showing the periphery of end portion 26b of rear barrel 26 in writing instrument 10 according to the fourth embodiment. As shown in Fig. 9, rear barrel 26 of the fourth embodiment has protrusion 401 instead of protrusion 34. Furthermore, friction body 14 is provided with recess 411 instead of recess 45. Protrusion 401 and recess 411 are substantially identical to protrusion 34 and recess 45, except as will be described below.

[0108] The protrusion 401 protrudes from the outer peripheral surface 33c of the rear end tube 33 at a position spaced apart from the ends of the rear end tube 33 in the forward direction Df and the rearward direction Db. The protrusion 401 has a substantially triangular cross section that tapers toward the rearward direction Db. The recess 411 is provided on the inner peripheral surface 42b at a position spaced apart from the ends of the outer tube portion 42 in the forward direction Df and the rearward direction Db. The protrusion 401 fits into the recess 411.

[0109] As the friction body 14 wears, the outer surface 41 a of the head 41 approaches the recess 46 and the end face 33 a of the rear end tube 33. Since the protrusion 401 and the recess 411 are spaced apart from the end face 33 a in the forward direction Df, they can be prevented from appearing to the outside before the recess 46.

[0110] Fifth Embodiment A fifth embodiment will be described below with reference to FIGS. 10 and 11. FIG. 10 is a perspective view showing the periphery of the end portion 26b of the rear body 26 according to the fifth embodiment. As shown in FIG. 10, the rear body 26 of the fifth embodiment has a protrusion 501 instead of the protrusion 34. Furthermore, the rear end cylinder 33 does not have the notch 38, and has multiple gate marks 505 instead of the two gate marks 33e. The gate marks 505 are an example of a second protrusion. The protrusion 501 and the gate marks 505 are substantially identical to the protrusion 34 and the gate marks 33e, except as will be described below.

[0111] The protrusion 501 has a side surface 501a and a curved surface 501b. The side surface 501a is provided at the radially outer end of the protrusion 501. The side surface 501a is formed in a cylindrical shape extending around the central axis Ax.

[0112] The curved surface 501b is provided at the corner between the end surface 33a of the rear end tube 33 and the side surface 501a of the protrusion 501. That is, the rear barrel 26 has a rounded chamfer at the corner between the end surface 33a of the rear end tube 33 and the side surface 501a of the protrusion 501. This improves the fluidity (moldability) of the resin when molding the friction body 14.

[0113] 11 is a cross-sectional view showing the periphery of end portion 26b of rear barrel 26 in writing instrument 10 of the fifth embodiment. As shown in FIG. 11, curved surface 501b is continuous with end surface 33a such that a tangent to one end of curved surface 501b extends along end surface 33a. Furthermore, curved surface 501b is continuous with side surface 501a such that a tangent to the other end of curved surface 501b extends along side surface 501a.

[0114] Each of the multiple gate marks 505 protrudes in the rear direction Db from the end surface 33a of the rear end cylinder 33. The gate marks 505 are formed, for example, by injecting material into the mold 60 from the gate 67, which is a pinpoint gate (pin gate). The diameter of the gate marks 505 may be set to be larger than the diameter required for the flow of material.

[0115] The friction body 14 of the fifth embodiment is provided with a plurality of recesses 511. The recesses 511 are an example of second recesses. The recesses 511 are recessed in the rear direction Db from the end of the head 41 in the forward direction Df.

[0116] The recesses 511 have a shape corresponding to the gate marks 505. Each of the multiple gate marks 505 fits into a corresponding one of the multiple recesses 511. As a result, the gate marks 505 restrict the friction body 14 from rotating around the central axis Ax relative to the rear axle 26.

[0117] As described above, friction body 14 is provided with recess 511 recessed from head 41. Rear barrel 26 has gate mark 505 that protrudes from rear end tube 33 and fits into recess 511 to restrict rotation of friction body 14 around central axis Ax of rear end tube 33 relative to rear end tube 33. This allows writing instrument 10 of this embodiment to simplify mold 60 and prevent friction body 14 from being displaced relative to rear barrel 26.

[0118] Furthermore, a curved surface 501b that is continuous with the end surface 33a and the side surface 501a of the protrusion 501 is provided at the corner between the end surface 33a of the rear end tube 33 and the side surface 501a of the protrusion 501. This allows the material of the friction body 14 to flow smoothly along the curved surface 501b when the friction body 14 is formed. This improves the formability of the friction body 14. Meanwhile, as in the first embodiment, the rear end tube 33 and the protrusion 501 suppress elastic deformation of the friction body 14 so that it is displaced in the rotational direction Dr, thereby suppressing peeling of the outer tube portion 42 and the inner tube portion 43 from the outer surface 31b of the end wall 31.

[0119] Sixth Embodiment A sixth embodiment will now be described with reference to FIGS. 12 and 13. FIG. 12 is a perspective view showing the periphery of the end portion 26b of the rear body 26 according to the sixth embodiment. As shown in FIG. 12, the rear end cylinder 33 of the sixth embodiment does not include the notch 38, and has multiple gate marks 601 instead of the two gate marks 33e. The gate marks 601 are an example of a second protrusion. The gate marks 601 are substantially identical to the gate marks 33e, except as described below.

[0120] The multiple gate marks 601 each protrude radially outward from the outer peripheral surface 33c of the rear end tube 33. The gate marks 601 are formed, for example, by injecting material into the mold 60 from a gate 67, which is a tunnel gate (submarine gate).

[0121] Fig. 13 is a cross-sectional view showing the periphery of the end portion 26b of the rear barrel 26 in the writing instrument 10 of the sixth embodiment. As shown in Fig. 13, the friction body 14 of the sixth embodiment is provided with a plurality of recesses 611. The recesses 611 are an example of second recesses.

[0122] The recesses 611 are recessed from the inner circumferential surface 42b of the outer cylinder portion 42. The recesses 611 have a shape corresponding to the gate marks 601. Each of the plurality of gate marks 601 fits into a corresponding one of the plurality of recesses 611. As a result, the gate marks 601 restrict the friction body 14 from rotating around the central axis Ax relative to the rear axle 26.

[0123] As described above, friction body 14 is provided with recess 611 recessed from outer tube portion 42. Rear barrel 26 has gate mark 601 that protrudes from rear end tube 33 and fits into recess 611 to restrict rotation of friction body 14 around central axis Ax of rear end tube 33 relative to rear end tube 33. This allows writing instrument 10 of this embodiment to simplify mold 60 and prevent friction body 14 from being displaced relative to rear barrel 26.

[0124] In the above embodiment, the plug 51 seals the through-hole 35. However, the plug 51 may be omitted. In this case, the shaft 11 and the friction body 14 are made of a material with high gas barrier properties (low gas permeability), thereby preventing the water content of the ink from evaporating from the ink occlusion body 12.

[0125] The above-described embodiments of the present invention do not limit the scope of the invention, but are merely examples within the scope of the invention. Some embodiments of the present invention may be modified, omitted, or added to the above-described embodiments, for example, with respect to at least part of the specific applications, structures, shapes, actions, and effects, without departing from the spirit of the invention.

Claims

1. A stationery item comprising: a member having an end wall, a first tube protruding from the end wall in a first direction, and a second tube protruding from the end wall in a second direction opposite to the first direction, wherein the end wall has a through hole connecting the space inside the first tube with the space inside the second tube; and a friction body having a base contacting the end of the second tube in the second direction, an outer part extending from the base to surround the second tube and contacting the end wall and the second tube, and an inner part extending from the base to be surrounded by the second tube and contacting the end wall and the second tube, and capable of thermally discoloring a trace made of thermochromic ink by frictional heat generated by rubbing the trace made of thermochromic ink.

2. The stationery of claim 1, wherein the member has a first protrusion that protrudes from the second tube in a direction intersecting the second direction at a position spaced from the end wall in the second direction and fits into a first recess provided in the outer portion.

3. The stationery according to claim 1, wherein the friction body is provided with a recess that extends across the base and the inner portion and communicates with the through hole.

4. The stationery of claim 1, further comprising a plug for sealing said through hole.

5. The stationery according to claim 4, wherein the friction body is gas permeable.

6. The stationery according to claim 1, wherein the member and the friction body are integrally formed by two-color molding.

7. The stationery of claim 1, wherein the member is provided with a notch recessed from the second tube, and the friction body is fitted into the notch, thereby restricting rotation of the friction body around the central axis of the second tube relative to the second tube.

8. The stationery of claim 1, wherein the friction body is provided with a second recess recessed from the base, the outer portion, or the inner portion, and the member has a second protrusion protruding from the second tube and fitting into the second recess to restrict the friction body from rotating around the central axis of the second tube relative to the second tube.

Images