Writing instrument and ink storage member

Abstract

In the present invention, a writing instrument 1 includes a shaft cylinder 2, an ink storage body 6 disposed inside the shaft cylinder 2 and impregnated with ink, an ink replenishment part 10 that is disposed behind the ink storage body 6 and that has a ventilation hole 12 and an ink discharge hole 13, and an ink storage member 20 that can be attached to a rear end part of the shaft cylinder 2 and can store ink. When the ink storage member 20 is attached to a rear end part of the shaft cylinder 2, the ink in the ink storage member 20 can be supplied to the ink storage body 6 through the ink discharge hole 13 of the ink replenishment part 10.

Description

Writing implement and ink storage member

[0001] The present invention relates to a writing instrument and an ink storage member.

[0002] Writing instruments are known that have an ink occlusion body disposed within a barrel and impregnated with ink, and a writing lead that serves as a pen tip that ejects ink guided from the ink occlusion body (see, for example, Patent Document 1). Examples of such writing instruments include paint markers, oil-based markers, water-based markers, and underline markers. From the standpoint of environmental protection, it is preferable that the ink occlusion body be refillable with ink when the ink guided from the ink occlusion body runs out during use and the writing instrument can no longer be used for writing.

[0003] The writing instrument described in Patent Document 1 has a barrel, an ink occlusion body disposed inside the barrel, and a stopper body that holds the pen tip. To refill the ink, the stopper body is removed from the barrel, and an ink refill tool containing ink is inserted into the front end of the barrel, allowing ink to be supplied to the ink occlusion body.

[0004] Japanese Patent Application Laid-Open No. 2019-142006

[0005] In the writing instrument described in Patent Document 1, touching the pen tip when removing the stopper can stain fingers, etc. Also, because the rear end of the barrel is closed, the air in the ink occlusion body cannot be properly replaced with the supplied ink when ink is supplied, which can cause the supplied ink to overflow from the ink occlusion body and ultimately the barrel. While overflowing of ink can be prevented by supplying ink slowly from the refill tool, refilling can sometimes take too long.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a writing instrument that allows ink to be easily and quickly replenished into an ink occlusion body.

[0007] According to one aspect of the present invention, there is provided a writing instrument comprising a barrel, an ink absorbing body arranged within the barrel and impregnated with ink, an ink refill section arranged rearward of the ink absorbing body and having an air hole and an ink ejection hole, and an ink storage member that can be attached to the rear end of the barrel and can contain ink, wherein when the ink storage member is attached to the rear end of the barrel, the ink in the ink storage member can be supplied to the ink absorbing body through the ink ejection hole of the ink refill section.

[0008] According to another aspect of the present invention, there is provided an ink storage member for a writing instrument, which is attachable to the rear end of a barrel having an ink refill section with an air hole and an ink ejection hole, and an ink absorbing body impregnated with ink disposed therein, and which contains ink, and which is configured so that when attached to the rear end of the barrel, the ink is supplied to the ink absorbing body through the ink ejection hole of the ink refill section.

[0009] The air vent may be located closer to the central axis of the barrel than the ink ejection hole. The air vent may be located on the central axis. The ink ejection holes may be located concentrically around the central axis. The ink occlusion body may be configured to have at least two types of capillary force.

[0010] According to the aspects of the present invention, a common effect is achieved in that a writing instrument is provided that allows ink to be replenished into the ink occlusion body easily and quickly.

[0011] FIG. 1 is a perspective view of a writing instrument according to an embodiment of the present invention. FIG. 2 is a longitudinal cross-sectional view of the writing instrument of FIG. 1. FIG. 3 is an exploded perspective view of the writing instrument of FIG. 1. FIG. 4 is a longitudinal cross-sectional view of an ink storage member. FIG. 5 is another longitudinal cross-sectional view of the ink storage member. FIG. 6 is an enlarged longitudinal cross-sectional view of the rear end of the barrel. FIG. 7 is a transverse cross-sectional view of the ink refill section. FIG. 8 is a partial cross-sectional perspective view of the barrel showing the ink refill section. FIG. 9 is another partial cross-sectional perspective view of the barrel showing the ink refill section. FIG. 10 is a perspective view of a lead holding member. FIG. 11 is a longitudinal cross-sectional view of the lead holding member. FIG. 12 is a cross-sectional view taken along line D-D in FIG. 11.

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Corresponding components throughout the drawings are designated by common reference numerals.

[0013] FIG. 1 is a perspective view of a writing instrument according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of the writing instrument of FIG. 1, and FIG. 3 is an exploded perspective view of the writing instrument of FIG.

[0014] The writing instrument 1 comprises a cylindrical barrel 2, a cylindrically-shaped front barrel 3 that fits inside the front end of the barrel 2, a lead retaining member 4 that fits inside the front end of the front barrel 3, a writing lead 5 held by the lead retaining member 4, an ink occlusion body 6 that is disposed inside the barrel 2 and is impregnated with ink, and a cylindrically-shaped ink storage member 20 that screws into the rear end of the barrel 2. An ink refill section 10 is formed on the inner surface of the barrel 2 near the rear end. The barrel 2 may also refer to the front barrel 3 and further the ink storage member 20 as well.

[0015] In this specification, in the axial direction of the writing instrument 1, the side of the writing lead 5 is defined as the "front" side, and the side opposite the writing lead 5 is defined as the "rear" side. In describing each component, the front and rear sides are defined based on the assembled state of the writing instrument 1. Furthermore, unless otherwise specified, the central axis refers to the central axis of the writing instrument 1, i.e., the barrel 2.

[0016] The writing instrument 1 is a writing instrument configured to eject ink guided from an ink occlusion body 6 from a writing core 5, and specifically, is a marking pen. The writing core 5 is composed of a porous body such as a sintered body, a fiber bundle, a foam, a sponge body, a felt body, or a porous body. The writing core 5 is a substantially U-shaped member, and both ends of the U are inserted into the ink occlusion body 6. The ink in the ink occlusion body 6 is guided throughout the writing core 5 by capillary force, allowing the ink to be ejected during writing. Note that the writing instrument 1 may be a paint marker, an oil-based marker, a water-based marker, or the like, as long as it is configured to eject ink guided from the ink occlusion body 6 from the writing core 5, and the shape of the writing core 5 may be formed as desired depending on the type of writing instrument.

[0017] When the ink guided from the ink occlusion body 6 runs out due to writing and writing with the writing instrument 1 becomes impossible, ink can be replenished into the ink occlusion body 6. Specifically, the ink storage member 20 is removed from the rear end of the barrel 2, and a new ink storage member 20 filled with ink is fitted in its place. The ink storage member 20 will be described with reference to Figures 4 and 5.

[0018] Figure 4 is a vertical cross-sectional view of the ink storage member 20, and Figure 5 is another vertical cross-sectional view of the ink storage member 20. In Figures 4 and 5, the upper side is the front side. Figure 4 shows the ink storage member 20 in an unused state. One end of the ink storage member 20, i.e., the rear end, is closed, allowing ink 25 to be stored inside. The other end of the ink storage member 20, i.e., the front end, is open. A cover member 30 is fitted onto the front end of the unused ink storage member 20 to prevent the ink 25 from leaking.

[0019] FIG. 5 shows the ink storage member 20 with the cover member 30 removed. The front end of the ink storage member 20 is formed with a small-diameter portion 21, which is smaller in diameter than the rear portion. A male thread portion 22 is formed on the outer circumferential surface of the small-diameter portion 21. As shown in FIG. 3, the threads of the male thread portion 22 are not formed in a continuous spiral, but rather as discontinuous threads arranged on a continuous spiral trajectory. That is, the threads of the male thread portion 22 are formed over a length corresponding to a predetermined rotation angle around the central axis and at equal intervals along the spiral direction. The regularly-formed threads result in multiple sets of threads aligned in the axial direction and at equal intervals along the circumferential direction. As shown in FIG. 5, a ring-shaped annular protrusion 23 is formed on the inner circumferential surface of the front end of the ink storage member 20. As shown in FIG. 6 (described later), a female thread portion 7 of a similar shape is formed on the inner circumferential surface of the rear end of the barrel 2, capable of threadably engaging with the male thread portion 22 of the ink storage member 20.

[0020] Referring to FIG. 4 , a closure member 31 is formed on the inside of the front end surface of the cover member 30, engaging with the inner circumferential surface of the front end of the ink storage member 20. The closure member 31 is a cylindrical protrusion extending rearward, and a ring-shaped engagement protrusion 32 is formed on the outer circumferential surface of the closure member 31. The inner circumferential surface of the cover member 30 is formed with a female thread (not shown) that can be threaded with the male thread portion 22 of the ink storage member 20. When the ink storage member 20 and the cover member 30 are threaded together, the engagement protrusion 32 of the closure member 31 inserted into the ink storage member 20 and the annular protrusion 23 of the ink storage member 20 overcome each other while undergoing elastic deformation, thereby completing the threaded engagement. As a result, the seal between the ink storage member 20 and the closure member 31 is improved, preventing ink leakage from the ink storage member 20. Furthermore, by threading the cover member 30 onto the ink storage member 20 filled with ink, the ink storage member 20 can be stored, transported, etc., in an unused state.

[0021] 1 and 2, the outer peripheral surface of the ink storage member 20 is formed so as to be flush with, i.e., integral with, the outer peripheral surface of the barrel 2 when attached to the barrel 2. The outer peripheral surface of the cover member 30 is also formed so as to be flush with, i.e., integral with, the outer peripheral surface of the ink storage member 20.

[0022] To refill the ink, the cover member 30 is removed from the unused ink storage member 20 with the front end facing upward to prevent ink leakage. Next, the already attached ink storage member 20 is removed from the barrel 2, and in its place, the unused ink storage member 20 is screwed onto the barrel 2 with the writing lead 5 of the writing instrument 1 facing upward. Next, when the writing instrument 1 is tilted so that the writing lead 5 faces downward, gravity causes the ink 25 inside the ink storage member 20 to move into the barrel 2 and further pass through the ink refill section 10. After passing through the ink refill section 10, the ink 25 is supplied to the ink occluder 6, completing the ink refill. The ink refill section 10 will be described with reference to Figures 6 to 9.

[0023] FIG. 6 is an enlarged longitudinal cross-sectional view of the rear end of the barrel 2. FIG. 7 is a transverse cross-sectional view of the ink refill unit 10. Specifically, FIG. 7(A) is a cross-sectional view taken along line A-A in FIG. 6, FIG. 7(B) is a cross-sectional view taken along line B-B in FIG. 6, and FIG. 7(C) is a cross-sectional view taken along line C-C in FIG. 6. Also, FIG. 8 is a partial cross-sectional perspective view of the barrel showing the ink refill unit 10, and FIG. 9 is another partial cross-sectional perspective view of the barrel showing the ink refill unit 10. Specifically, FIGS. 8 and 9 are perspective views of the barrel 2 cut out near the ink refill unit 10, with FIG. 8 being a perspective view of the ink refill unit 10 seen from the rear side of the barrel 2 and FIG. 9 being a perspective view of the ink refill unit 10 seen from the front side of the barrel 2.

[0024] A female thread 7 is formed near the rear end of the barrel 2, which can be threadedly engaged with the male thread 22 of the ink storage member 20. Like the male thread 22 of the ink storage member 20, the female thread 7 has a plurality of threads arranged in the same spiral, aligned in the axial direction, and equally spaced along the circumferential direction. As described above, an ink refill section 10 is formed on the inner surface near the rear end of the barrel 2. The ink refill section 10 has a partition 11 that crosses the inner surface of the barrel 2. The partition 11 is provided with an air vent 12 and two ink discharge holes 13 that penetrate the partition 11 in the axial direction. Three ribs 8 are formed in front of the partition 11, equally spaced along the circumferential direction. The ribs 8 have inclined surfaces 9 facing forward. The ink occlusion body 6 inserted into the barrel 2 from the front is guided toward the center by the inclined surfaces 9 of the ribs 8 so that the central axes of the barrel 2 and the ink occlusion body 6 coincide. As a result, the ink occlusion body 6 is fixed to the barrel 2 so as to be sandwiched between the ribs 8 .

[0025] As shown in FIG. 8 in particular, a first cylindrical wall 14 is formed rearward from the partition wall 11, and a second cylindrical wall 15 is formed cylindrically surrounding the first cylindrical wall 14. The central axes of the first cylindrical wall 14 and the second cylindrical wall 15 coincide with the central axis of the barrel 2. A fitting space 16 is defined between the outer circumferential surface of the second cylindrical wall 15 and the inner circumferential surface of the barrel 2. When the ink storage member 20 is attached to the barrel 2, the small diameter portion 21 of the ink storage member 20 fits into the fitting space 16, filling it. This prevents ink that flows from the ink storage member 20 into the barrel 2 during ink refilling from accumulating around the second cylindrical wall 15, allowing all of the ink to be impregnated into the ink occlusion body 6.

[0026] 7(B), a circular through-hole 11a having a diameter equal to the inner diameter of the first cylindrical wall 14 is formed in the partition wall 11. A cylindrical air vent 12 is defined by the through-hole 11a that penetrates the interior of the first cylindrical wall 14 and the partition wall 11. Therefore, the air vent 12 is provided on the central axis of the barrel 2, and communicates with the front and rear of the partition wall 11.

[0027] As shown in FIG. 7B , two arc-shaped through holes 11b are formed around the through hole 11a of the partition wall 11, corresponding to portions of the cylindrical space defined between the first cylindrical wall 14 and the second cylindrical wall 15. The two through holes 11b are arranged symmetrically with respect to the central axis. As shown in FIG. 7C , two donut-shaped abutment protrusions 17 are formed forward from the partition wall. The two abutment protrusions 17 are equally divided by a radially extending slit 18 and arranged symmetrically. The diameter of the circumscribed circle of the two abutment protrusions 17 is smaller than the outer diameter of the ink occlusion body 6. The two through holes 11b penetrate the corresponding abutment protrusions 17 in the axial direction. Two ink ejection holes 13 are defined by the cylindrical space defined between the first cylindrical wall 14 and the second cylindrical wall 15, as well as the two through holes 11b penetrating the partition wall 11 and the abutment protrusions 17. Therefore, the two ink ejection holes 13 are arranged concentrically around the central axis of the barrel 2, and communicate with the front and rear of the partition wall 11. When the writing instrument 1 is assembled, the front end face of the abutting protrusion 17 is completely covered by the rear end face of the ink occlusion body 6, so the outlet of the ink ejection hole 13 abuts against the ink occlusion body 6.

[0028] As described above, to refill ink, an unused ink storage member 20 is screwed onto the barrel 2 with the writing lead 5 of the writing instrument 1 facing upward, and then the writing instrument 1 is tilted so that the writing lead 5 faces downward. As a result, the ink inside the ink storage member 20 passes by gravity through the ink discharge hole 13 of the ink refill section 10 and is supplied from the rear end face of the ink occlusion body 6 into the ink occlusion body 6. More specifically, as the writing instrument 1 is tilted, the ink descends along the wall surface of the ink storage member 20. The ink discharge hole 13 is located farther from the central axis of the barrel 2 or the ink storage member 20 than the air vent 12, i.e., is located radially outward of the air vent 12. Therefore, the ink continues to descend through the ink discharge hole 13 before passing through the air vent 12. In particular, the front end face of the abutment protrusion 17, which is the outlet of the ink ejection hole 13, abuts against the ink absorbing body 6, specifically the fibrous body 6b described later, so that the ink that has passed through the ink ejection hole 13 can be supplied directly to the ink absorbing body 6.

[0029] The through-hole 11a provided in the partition wall 11, which is the entrance of the ventilation hole 12, is separated from the ink occlusion body 6 by the contact protrusions 17, and therefore communicates with the slit 18 between the two contact protrusions 17. The slit 18 communicates with the interior of the barrel 2, specifically the space between the inner circumferential surface of the barrel 2 and the outer circumferential surface of the ink occlusion body 6, and therefore the ventilation hole 12 communicates with the interior of the barrel 2.

[0030] As described above, when ink is supplied to the rear end surface of the ink occlusion body 6, the ink gradually permeates from the rear to the front. As the ink permeates, the air inside the ink occlusion body 6 also gradually moves from the rear to the front and is discharged from the front end surface of the ink occlusion body 6. The air pushed out from the front end surface of the ink occlusion body 6 passes through the space between the inner circumferential surface of the barrel 2 and the outer circumferential surface of the ink occlusion body 6 and flows into the ink storage member 20 through the vent hole 12. In other words, when ink is supplied into the ink occlusion body 6 through the ink discharge hole 13, the air inside the ink occlusion body 6 equivalent to that volume flows into the ink storage member 20 through the vent hole 12. Because the flow directions of the ink and the air are aligned within the ink occlusion body 6, ink can be quickly replenished.

[0031] Furthermore, refilling the ink in the writing instrument 1 can be accomplished simply by removing the ink storage member 20 attached to the rear end of the writing instrument 1 and which has already been emptied of ink, and then simply replacing it with an unused ink storage member 20. Therefore, unlike the writing instrument described in Patent Document 1, there is no need to remove the stopper having the nib, so there is no risk of fingers or the like getting soiled by the writing core 5, and there is no need to worry about ink spilling during the refilling process. Therefore, with the writing instrument 1, refilling the ink can be done easily and quickly.

[0032] The cross-sectional area of ​​the ink ejection hole 13 is formed to be smaller than that of the air vent 12. Therefore, assuming that the same amount of ink passes through, the capillary force in the ink ejection hole 13, which has a smaller cross-sectional area and is a narrower flow path, is greater than the capillary force in the air vent 12, which has a larger cross-sectional area and is a wider flow path. Therefore, when ink passes through the ink ejection hole 13, the flow of the ink can be promoted by the action of capillary force.

[0033] As described above, the writing instrument 1 is configured so that, when the ink storage member 20 is attached to the rear end of the barrel 2, refill ink in the ink storage member 20 can be supplied to the ink occlusion body 6 through the ink discharge hole 13 of the ink refill unit 10. The ink refill unit 10 only needs to be located rearward of the ink occlusion body 6, and therefore may be located inside the ink storage member 20 rather than inside the barrel 2. The ink refill unit 10 may also be configured as a separate unit that can be inserted into the barrel 2 or the ink storage member 20. The shape, number, and location of the air vents 12 and ink discharge holes 13 can be selected as desired, as long as the air vents 12 are located closer to the central axis of the barrel 2 than the ink discharge holes 13 so that ink passes through the ink discharge holes 13 first when the writing instrument 1 is tilted. The air vents 12 are preferably located on the central axis, but may be located off the central axis. The ink ejection holes 13 are preferably arranged concentrically around the central axis of the barrel 2, but do not have to be arranged concentrically.

[0034] Ink supplied to the ink occlusion body 6 from the ink storage member 20 via the ink refill unit 10 is impregnated throughout the ink occlusion body 6 due to the action of capillary force within the ink occlusion body 6. This eliminates uneven ink ejection during writing and makes it possible to use ink without waste. Taking into account the difference in fluidity between air and ink, it is preferable that the ink occlusion body 6 have at least two types of capillary force. The ink occlusion body 6 will be described below.

[0035] As shown in Figure 2, the ink occlusion body 6 is composed of an outer skin 6a and a fibrous body 6b, which is a bundle of multiple long fibers arranged in the longitudinal direction. Examples of fibers include natural fibers, animal hair fibers, fibers made of polyacetal resin, acrylic resin, and polyester resin. The ink occlusion body 6 is formed into a cylindrical shape as a whole by the outer skin 6a surrounding the fibrous body 6b. At both ends of the ink occlusion body 6, the fibrous body 6b is trimmed to form circular end faces with the exposed fibrous body 6b.

[0036] The outer cover 6a is a sheet-like member. The outer cover 6a may be made of a material that does not have capillary force, such as a synthetic resin film, or may be made of a material that has capillary force, such as a nonwoven fabric. By making the outer cover 6a from a breathable material such as a nonwoven fabric, air can be discharged from the inside of the ink occlusion body 6 to the outside when refilling the ink.

[0037] In the fibrous body 6b, countless flow paths for ink and air are formed by the minute gaps between the fibers. As described above, when ink is supplied from the ink occlusion body 6 to the ink occlusion body 6, i.e., the fibrous body 6b, the ink penetrates into the minute gaps between the fibers. The ink penetrates into the entire fibrous body 6b within the minute gaps due to capillary force. At this time, by adjusting the density of the fibers that make up the fibrous body 6b, i.e., the size of the gaps between the fibers, the strength of the capillary force can be adjusted, and the penetration of the ink can be promoted. The density of the fibers that make up the fibrous body 6b can be adjusted, for example, by the thickness of the fibers.

[0038] When the fibrous body 6b is composed of thicker and thinner fibers, the fibrous body 6b has two types of capillary force. However, when the fibrous body 6b is composed of fibers of different thicknesses, the fibers are not mixed, but are unevenly distributed with fibers of the same thickness. The portions composed of thicker fibers have larger gaps than the portions composed of thinner fibers, and therefore the capillary force is weaker. With an ink occlusion body 6 composed of fibrous body 6b composed of fibers of two types of thickness, the supplied ink is preferentially absorbed into the gaps between the thinner fibers, which have a stronger capillary force, and the gaps between the thicker fibers become air flow paths, facilitating the discharge of air. The fibrous body 6b may also be composed of fibers of three or more types of thickness.

[0039] Experiments conducted using specific examples regarding the presence or absence of the ink refill portion 10 of the writing instrument 1 and the differences in the fibers that make up the fibrous body 6b of the ink occlusion body 6 will be described below.

[0040] The cylindrical ink occlusion body 6 had an outer diameter of 6.5 mm and a total length of 60 mm, and Examples 1 to 8 and Comparative Examples 1 and 2 were prepared as follows. In Examples 1 to 8, the ink occlusion body was set in a writing instrument having an ink refill section, i.e., a writing instrument having two types of flow paths: an air vent and an ink ejection hole. In Comparative Examples 1 and 2, the ink occlusion body was set in a writing instrument not having an ink refill section, i.e., a writing instrument with no barrier between the ink storage member and the ink occlusion body.

[0041] <Examples> Example 1: An ink occlusion body obtained by enclosing a fibrous body consisting of 11,000 3 dtex fibers and 460 2 dtex fibers in a skin made of PET film was set in a writing instrument having an ink refill section. Example 2: An ink occlusion body obtained by enclosing a fibrous body consisting of 12,000 3 dtex fibers and 500 2 dtex fibers in a skin made of PET film was set in a writing instrument having an ink refill section. Example 3: An ink occlusion body obtained by enclosing a fibrous body consisting of 10,000 3 dtex fibers and 400 2 dtex fibers in a skin made of PET film was set in a writing instrument having an ink refill section. Example 4: An ink occlusion body obtained by enclosing a fibrous body consisting of 10,000 3 dtex fibers and 50 15 dtex fibers in a skin made of PET film was set in a writing instrument having an ink refill section. Example 5: An ink occlusion body obtained by enclosing a fibrous body consisting of 9,000 3 dtex fibers, 460 2 dtex fibers, and 50 15 dtex fibers in a skin made of PET film was set in a writing instrument having an ink refill section. Example 6: An ink occlusion body obtained by enclosing a fibrous body consisting of 12,000 3 dtex fibers in a skin made of nonwoven fabric was set in a writing instrument having an ink refill section. Example 7: An ink occlusion body obtained by enclosing a fibrous body consisting of 12,000 3 dtex fibers in a skin made of PET film was set in a writing instrument having an ink refill section. Example 8: An ink occlusion body obtained by enclosing a fibrous body consisting of 14,000 3 dtex fibers in a skin made of PET film was set in a writing instrument having an ink refill section. Comparative Examples Comparative Example 1: An ink occlusion body obtained by surrounding a fibrous body consisting of 12,000 3 dtex fibers with an outer skin made of PET film was set in a writing instrument having no ink refill section. Comparative Example 2: An ink occlusion body obtained by surrounding a fibrous body consisting of 14,000 3 dtex fibers with an outer skin made of PET film was set in a writing instrument having no ink refill section.

[0042] <Experimental Method> The ink occlusion body was impregnated with 1.7 g of ink in advance, and 1.3 g of ink was ejected by writing. Next, an unused ink storage member was attached to the barrel, and 1.2 g of ink was supplied to the ink occlusion body. The time until the supplied ink was completely impregnated into the ink occlusion body was measured.

[0043] <Experimental Results> The ink impregnation times in Examples 1 to 8 were 25 seconds in Example 1, 20 seconds in Example 2, 30 seconds in Example 3, 15 seconds in Examples 4 to 6, 45 seconds in Example 7, and 40 seconds in Example 8. The ink impregnation times in Examples 1 to 8 were all within 1 minute, and in particular, the ink impregnation times in Examples 1 to 6 were all good, being within 30 seconds. On the other hand, with regard to the ink impregnation times in Comparative Examples 1 and 2, some of the ink remained unimpregnated even after 600 seconds had elapsed in both Comparative Examples 1 and 2.

[0044] Examples 7 and 8 differ from their corresponding Comparative Examples 1 and 2 only in the presence or absence of an ink refill unit. However, as described above, there is a significant difference in the ink soaking time, demonstrating the effectiveness of the ink refill unit. Specifically, the ink forms a concave film due to surface tension inside the barrel behind the ink occluder or on the inner surface of the ink storage member. When the writing instrument is tilted in this state to move the ink forward, Comparative Examples 1 and 2, which do not have an ink refill unit, do not properly contact the ink with the ink occluder, and therefore the ink does not properly penetrate the ink occluder. On the other hand, in Examples 1 to 8, which have an ink refill unit 10, when the entrance of the ink ejection hole 13 comes into contact with the ink liquid surface, the ink is drawn into the ink ejection hole 13 by capillary force. As a result, the ink is ejected from the exit of the ink ejection hole 13 and efficiently supplied sequentially to the ink occluder 6.

[0045] Examples 4 to 6 all had the shortest ink soaking time of 15 seconds, for the following reasons: The ink occlusion bodies of Examples 4 and 5 contain thicker 15 dtex fibers compared to the other examples, resulting in larger gaps between the fibers. Therefore, within a single ink occlusion body, two types of capillary force are present: a stronger capillary force due to the narrower gaps between fibers such as 3 dtex, and a weaker capillary force due to the wider gaps between 15 dtex fibers. This allows for efficient flow of ink and exhausted air. Example 6 has a nonwoven fabric outer skin, which allows air to be efficiently exhausted from the inside to the outside of the ink occlusion body 6 during ink refilling, resulting in efficient flow of ink and exhausted air. The ink occlusion bodies of Examples 1 to 3 contain 2 dtex and 3 dtex fibers, but no 15 dtex fibers. Therefore, the ink soaking time is longer than that of the ink occlusion bodies of Examples 4 and 5 containing 15 dtex fibers, but the flow of supplied ink and the flow of discharged air are efficient.

[0046] For these reasons, it is preferable that the ink occlusion body be configured to have at least two types of capillary force. The two types of capillary force may be capillary force obtained due to differences in the fibers that make up the fibrous body, or the effect obtained from the material of the outer skin, such as nonwoven fabric, may also be referred to as capillary force. In other words, the fibrous body may contain one type of fiber and the outer skin may be formed from a material such as nonwoven fabric, thereby having two or more types of capillary force.

[0047] As mentioned above, since the effect of the ink refill section can be obtained regardless of the configuration of the ink absorbing body, the ink absorbing body may be configured not as a fibrous body made of fibers, but as a porous body such as a sponge, resin particles, or a sintered body.

[0048] Figure 10 is a perspective view of the lead holding member 4, Figure 11 is a longitudinal cross-sectional view of the lead holding member 4, and Figure 12 is a cross-sectional view taken along line D-D in Figure 11. The lead holding member 4 has a main body 40 formed in the shape of a trapezoidal flat plate, a fitting portion 41 provided at the rear of the main body 40 and configured to fit into the interior of the front end of the tip barrel 3, a holding groove 42 provided on the outer periphery of the main body 40 and the fitting portion 41 and configured to fit into the substantially U-shaped writing lead 5, and a visible portion 43 provided on the side of the main body 40.

[0049] The visible portion 43 comprises a through hole 44 provided in the main body portion 40 and three beam members 45 extending in the longitudinal direction of the core holding member 4 inside the through hole 44. As shown in Figure 12, each of the beam members 45 has a rectangular cross section with approximately the same width and height.

[0050] The provision of the beam members 45 within the through-holes 44 prevents the lead holding member 4 from bending excessively due to the writing pressure applied when writing. In other words, the flexibility of the lead holding member 4 can be adjusted by adjusting the number, shape, width, etc. of the beam members 45. Furthermore, when writing with the writing instrument 1, which is a marking pen, the user can see the characters written in the writing direction through the visible portion 43, particularly the through-holes 44. The beam members 45 are provided to extend in the longitudinal direction of the through-holes 44, but may also be provided to extend diagonally or in the short direction rotated 90 degrees.

[0051] Furthermore, the lead holding member 4 is preferably made of a synthetic resin material having a compression set of less than 80% at 120°C and a Shore A hardness of 60 to 95. Specifically, it is a styrene-based elastomer selected from the group consisting of styrene-ethylene-propylene-styrene (SEPS) in which styrene is replaced with p-methylstyrene, styrene-ethylene-ethylene-propylene-styrene (SEEPS) in which styrene is replaced with p-methylstyrene, and styrene-ethylene-butadiene-styrene (SEBS) in which styrene is replaced with p-methylstyrene. Using a styrene-based elastomer for the lead holding member 4 not only provides appropriate elasticity during writing, but also prevents damage to the writing lead 5 due to excessive writing load.

[0052] REFERENCE SIGNS LIST 1 Writing implement 2 Barrel 3 Tip barrel 4 Lead holding member 5 Writing lead 6 Ink occluder 10 Ink refill section 11 Partition wall 12 Vent hole 13 Ink ejection hole 14 First cylindrical wall 15 Second cylindrical wall 16 Fitting space 17 Contact protrusion 18 Slit 20 Ink storage member 21 Small diameter section 22 Male thread section 23 Annular protrusion 25 Ink

Claims

1. A writing instrument comprising a barrel, an ink absorbing body disposed within the barrel and impregnated with ink, an ink refill section disposed rearward of the ink absorbing body and having an air hole and an ink ejection hole, and an ink storage member attachable to the rear end of the barrel and capable of containing ink, characterized in that when the ink storage member is attached to the rear end of the barrel, the ink in the ink storage member can be supplied to the ink absorbing body through the ink ejection hole of the ink refill section.

2. The writing implement according to claim 1, wherein the air hole is provided on the central axis of the barrel further than the ink ejection hole, and the ink ejection hole is provided concentrically around the central axis.

3. An ink storage member for a writing instrument, which is attachable to the rear end of a barrel having an ink refill section with an air hole and an ink ejection hole, and an ink absorbing body impregnated with ink disposed therein, and which contains ink, characterized in that when attached to the rear end of the barrel, the ink is supplied to the ink absorbing body through the ink ejection hole of the ink refill section.

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