JP7675764B2 - Writing implement set - Google Patents

Description

The present invention relates to a writing instrument set.

A writing instrument set having multiple writing instruments and a case capable of housing the multiple writing instruments is known (for example, Patent Document 1). The writing instrument set described in Patent Document 1 has three writing instruments. The case has an elongated opening at one end. The case houses the three aligned writing instruments such that the rear ends of the three aligned writing instruments protrude from the opening end. A slit extending in the axial direction is formed at each end of the opening end of the case. In the case, two wall portions arranged opposite each other between the two slits are elastically deformable so that the slits widen, i.e., so that the opening of the case becomes larger.

A protrusion is formed on the side surface near the rear end of each writing instrument. When the writing instrument is stored, a small hole is formed in the wall of the case corresponding to each of the protrusions of the writing instrument. When the writing instrument is stored in the case, the protrusion of the writing instrument presses against the wall as the writing instrument is inserted into the case, causing the wall to elastically deform. The elastic deformation of the wall is restored when the protrusion reaches and fits into the small hole in the case. The wall also elastically deforms when the writing instrument is removed from the case, and the elastic deformation of the wall is restored when the protrusion of the writing instrument passes the opening edge.

Japanese Utility Model Application Publication No. 63-70391

When using a writing instrument, the writing instrument is stored in and removed from the case, that is, attached and detached. Repeated attachment and detachment causes the protrusions of the writing instrument to wear down due to friction with the surface of the wall. In particular, repeated attachment and detachment may cause the protrusions to be scraped off by the edge of the opening. Repeated attachment and detachment may also cause the slits of the case, i.e., the wall, to plastically deform, leaving the opening large. As a result, the fitting or engagement force between the writing instrument and the case may decrease, and the writing instrument may unintentionally come off the case. In addition, because the protrusions are provided in conspicuous positions on the side of the writing instrument, especially on the side near the rear end, there are restrictions on the shape of the barrel of the writing instrument and on the design, such as the pattern.

The present invention aims to provide a writing instrument set whose engagement force does not decrease even when it is repeatedly attached and detached.

According to one aspect of the present invention, there is provided a writing instrument set comprising a plurality of writing instruments and a case capable of storing the plurality of writing instruments in an aligned state, characterized in that a first engagement portion is provided on the writing portion side of the writing instruments and a second engagement portion is provided inside the case, and each of the writing instruments can be attached to and detached from the case by engaging or disengaging the first engagement portion and the second engagement portion.

The case may further include a slide member, the second engagement portion being provided on the slide member, and the case having an operating portion, and the slide member may be moved rearward by operating the operating portion, thereby enabling the writing instrument to be removed.

The plurality of writing instruments may include a thermochromic writing instrument and a non-thermochromic writing instrument. In this case, the flexural modulus of the writing instrument body of the thermochromic writing instrument may differ by 300 MPa or more, preferably by two times or more, from the flexural modulus of the writing instrument body of the non-thermochromic writing instrument. This results in a different writing feel on the writing instrument body when writing, making it possible to recognize the difference between the thermochromic writing instrument and the non-thermochromic writing instrument. The flexural modulus can be determined by a measurement in accordance with JIS K7171.

The plurality of writing implements may include at least two writing implements containing different achromatic inks, and the writing implement body of the writing implement with the darker line density of the achromatic ink may be black, and the writing implement body of the writing implement with the lighter line density of the ink may be a color other than black. By making each of the writing implement bodies black and a color other than black (for example, gray or white, which are achromatic colors brighter than black), it becomes easier for color-blind people to recognize the color of the ink contained therein.

The aspects of the present invention have the common effect of providing a writing instrument set whose engagement force does not decrease even when it is repeatedly attached and detached.

FIG. 1 is a perspective view of a writing instrument set according to an embodiment of the present invention, in which writing instruments are stored. FIG. 2 is another perspective view of the writing instrument set of FIG. FIG. 3 is a perspective view of the writing instrument set of FIG. 1 in a state where the writing instrument is removed. FIG. 4 is a perspective view of the writing instrument. FIG. 5 is a vertical cross-sectional view of the writing instrument set of FIG. FIG. 6 is a perspective view of the slide member. FIG. 7 is a perspective view of the cover member. FIG. 8 is an enlarged vertical cross-sectional view of the front end portion of the writing instrument set of FIG. FIG. 9 is an enlarged vertical cross-sectional view of the writing instrument set as viewed from an angle different from that of FIG. FIG. 10 is an enlarged vertical cross-sectional view of the front end portion of the writing instrument set of FIG. FIG. 11 is an enlarged vertical cross-sectional view of the writing instrument set as viewed from an angle different from that of FIG. FIG. 12 is an enlarged vertical cross-sectional view of the writing instrument set in a position different from that in FIG. FIG. 13 is a perspective view of another case body. FIG. 14 is a front view of the clip member. FIG. 15 is a side view of the clip member. FIG. 16 is a cross-sectional view taken along line XX in FIG. FIG. 17 is a cross-sectional view taken along line YY in FIG. FIG. 18 is an enlarged view of part A in FIG.

Embodiments of the present invention will now be described in detail with reference to the drawings. Corresponding components are designated by common reference symbols throughout the drawings.

Figure 1 is a perspective view of a writing instrument set 1 according to an embodiment of the present invention in a stored state of a writing instrument 40, Figure 2 is another perspective view of the writing instrument set 1 of Figure 1, and Figure 3 is a perspective view of the writing instrument set 1 of Figure 1 in a removed state of the writing instrument 40. Also, Figure 4 is a perspective view of the writing instrument 40.

The writing instrument set 1 has a case body 10, a cover member 20, a slide member 30 (described later), three writing instruments 40, and a clip member 50. The clip member 50 is attached to the side of the opening end of the case body 10 by adhesion or the like.

The cover member 20 is removably attached to the case body 10 and covers a substantially rectangular opening formed on the side of the closed end of the case body 10. The case body 10, the cover member 20, and the slide member 30 thereby constitute the case 2. The case 2 is open at one end and closed at the other end. The case 2 is configured to be capable of housing three writing instruments 40 in an aligned state. The case 2 may be configured to be capable of housing two or four or more writing instruments 40.

The cover member 20 is provided with an operating unit 21. As described below, when the writing instrument set 1 is in the storage state of the writing instrument 40 shown in FIG. 1, by operating the operating unit 21, the writing instrument set 1 is in the removal state of the writing instrument 40 shown in FIG. 3. In this state, the user can remove the writing instrument 40 from the case 2 by grasping the protruding end of the writing instrument 40.

As shown in FIG. 13, the clip member 50 may be omitted from the case 2. In this case, the flat surface 13 in a shallow recess provided in the case body 10 where the clip member 50 should be placed is exposed. The flat surface 13 may be provided with a design such as a pattern or letters. In this case, a transparent film with letters written on it may be transfer-printed onto the flat surface 13, so that the letters will not easily peel off even if they are applied to the flat surface 13. For example, the flat surface 13 may be inscribed with a company name or the like in order to distribute it as a novelty item. The flat surface 13 may also be formed flush with the side surface of the case body 10, rather than within the recess.

The writing instrument 40 has a writing instrument body 41 which is a cylindrical member formed into a cylindrical shape, a writing portion 42 provided at one end of the writing instrument body 41, a grip portion 43 provided on the outer peripheral surface of the writing instrument body 41 on the writing portion 42 side in the axial direction, and an identification portion 44 provided at the other end of the writing instrument body 41. A first engagement portion 45 which is an annular protrusion is formed on the writing portion 42 side of the writing instrument 40 in the axial direction, specifically near the writing portion 42. The multiple writing instruments 40 are stored in the case 2 in an aligned manner so that each of the writing portions 42 is stored inside the case 2.

In this specification, in the axial direction of the writing instrument 40, the side of the writing part 42 is defined as the "front" side, and the side opposite the writing part 42 is defined as the "rear" side. Also, in the axial direction of the case 2, when the writing instrument 40 is stored, the side where the writing part 42 of the writing instrument 40 is located, i.e., the closed end side, is defined as the "front" side, and the side opposite the writing part 42, i.e., the open end side, is defined as the "rear" side.

The writing instruments 40 may be any writing instrument or combination of writing instruments as long as they have substantially the same external shape that can be accommodated in the case 2, particularly an external shape that can be accommodated in an aligned state. In particular, the writing instruments 40 may be any shape as long as the first engagement portion 45 is formed in a relatively identical location. The writing instrument 40 may also be a thermochromic writing instrument such as a thermochromic ballpoint pen in which a refill, which is a writing body that contains thermochromic ink and has a writing portion 42 at one end, is accommodated in the writing instrument body 41. The writing instrument 40 may also be a non-thermochromic writing instrument such as a ballpoint pen, a felt tip pen, a marker pen, a mechanical pencil, a calligraphy pen, and a fountain pen. For example, the multiple writing instruments 40 accommodated in the writing instrument set 1 may include at least one thermochromic writing instrument and at least one non-thermochromic writing instrument.

In order to identify the multiple writing instruments 40 contained in the writing instrument set 1, the rear of each writing instrument 40 has an identification section 44 with a different shape or pattern. For example, the identification section 44 may be made to have different numbers of annular grooves or different colors in the grooves as shown in FIG. 4, so that each writing instrument 40 can be identified. For example, a writing instrument 40 with one annular groove may be a thermochromic ballpoint pen, a writing instrument 40 with two annular grooves may be a thermochromic marking pen, and a writing instrument 40 with three annular grooves may be a non-thermochromic ballpoint pen. Similarly, in order to identify the multiple writing instruments 40 contained in the writing instrument set 1, each writing instrument 40 may have a grip section 43 with a different shape or pattern.

The multiple writing instruments 40 contained in the writing instrument set 1 may include at least two writing instruments 40 containing different achromatic inks. The writing instrument body 41 of the writing instrument 40 with the darker ink line density may be black, and the writing instrument body 41 of the writing instrument 40 with the lighter ink line density may be a color other than black, such as gray or white. The black color of the writing instrument body 41 is determined visually. By making each of the writing instrument bodies 41 black and a color other than black, it becomes easier for color-blind people to recognize the ink color contained therein.

Here, achromatic ink refers to black, gray, and white, and specifically refers to colors in which a* and b* are in the range of -5 to 5 in the color space based on the L*a*b* color system. In order to measure achromatic ink, the ink in the writing implement 40 is spread on Clark Kent paper (ream weight 160 kg) using a bar coater (RDS06, Yasuda Seiki Seisakusho Co., Ltd.), and the L*, a*, and b* are obtained by measuring the spread sample based on JIS Z 8781-4:2013. For the measurement, a spectrophotometer (SC-T (P), manufactured by Suga Test Instruments Co., Ltd.) is used, and the optical conditions are diffuse illumination 8° light receiving d8 method (excluding regular reflection), light source: 12V 50W halogen lamp, color measurement conditions: D65 light, 2° field of view, measurement temperature: -30°C, measurement area: 5φ (average of measurements at three points).

The line density of the ink is evaluated by its lightness value, and is measured using the Munsell color system with a measuring device such as a general-purpose color difference meter (TC-8600A, manufactured by Tokyo Denshoku Co., Ltd.) on lines drawn on paper (old JIS P3201: wood-free paper made from 100% chemical pulp, basis weight range 40 to 157 g/ ^m2 , whiteness 75.0% or more) at -30°C at a writing speed of 4.5 m/min and a pitch interval of 0.1 mm. Inks with higher lightness values are evaluated as having darker line density.

When the multiple writing instruments 40 contained in the writing instrument set 1 include thermochromic writing instruments 40 and non-thermochromic writing instruments 40, the flexural modulus of the writing instrument body 41 of the thermochromic writing instruments 40 may differ from the flexural modulus of the writing instrument body 41 of the non-thermochromic writing instruments 40 by 300 MPa or more, preferably by a factor of two or more. This results in a different writing feel on the writing instrument body 41 when writing, making it possible to recognize the difference between the thermochromic writing instruments 40 and the non-thermochromic writing instruments 40. The flexural modulus can be determined by measurements in accordance with JIS K7171.

Figure 5 is a vertical cross-sectional view of the writing instrument set 1 of Figure 1. Also, Figure 6 is a perspective view of the slide member 30. The case body 10 has two holding projections 11 formed on the inner front end surface and two guide projections 12 formed on the opposing wall portions. Each of the holding projections 11 is configured to hold one end of the spring 51. The guide projections 12 extend along the axial direction and are configured to guide the forward and backward movement of the writing instrument 40 inserted into the case 2.

A slide member 30 is disposed inside the case body 10 so as to be movable in the front-rear direction. As described below, the movement of the slide member 30 in the front-rear direction is restricted within a predetermined range by a cover member 20 attached to the case body 10.

The slide member 30 has three aligned insertion holes 31 that face rearward and extend in the axial direction. Each of the insertion holes 31 is configured to be able to receive the front end of a corresponding writing instrument 40 inserted into the case 2. The slide member 30 also has two retaining holes 32 that face forward and extend in the axial direction at positions corresponding to the insertion holes 31 at both ends. Each of the retaining holes 32 is configured to be able to receive a spring 51. One end of the spring 51 received in the retaining hole 32 is supported by the support surface 33, which is the annular bottom surface of the retaining hole 32. Therefore, the front end of the spring 51 is held by the retaining protrusion 11, and the other end of the spring 51 is supported by the support surface 33. As a result, the slide member 30 is constantly urged rearward by the two springs 51.

The slide member 30 will be further described with reference to FIG. 6. A second engagement portion 34 consisting of four protrusions evenly arranged along the circumferential direction is formed on the inner peripheral surface near the opening end of each of the insertion holes 31. A locking piece 35 is provided on the side surface of the slide member 30 corresponding to the operating portion 21 of the cover member 20 inside the case 2. The locking piece 35 is a beam-shaped member that is defined by a U-shaped groove 36 that penetrates through it and extends toward the rear. A first locking surface 37 is formed on the rear end surface of the locking piece 35. In addition, an inclined surface 38 that is inclined toward the rear is formed on the surface of the locking piece 35. Furthermore, two second locking surfaces 39 defined by two recesses or two protrusions are formed on the rear end surface of the slide member 30.

7 is a perspective view of the cover member 20. In the perspective view of FIG. 7, the cover member 20 is viewed from the inside. As described above, the cover member 20 is provided with the operating portion 21. Specifically, the operating portion 21 is a beam-shaped member that is defined by a through-hole arc-shaped groove 22 and extends toward the rear. An arc-shaped protrusion 23 is formed on the inner surface of the rear end of the operating portion 21. Two parallel rib protrusions 24 that extend rearward along the axial direction are formed on the inner surface of the cover member 20 behind the protrusion 23. A first engaged surface 25 is formed on the front end surface of each of the rib protrusions 24. A recess 26 is formed in the middle of the rib protrusion 24. Two second engaged surfaces 27 that are defined by the two protrusions and face forward are formed on the inner surface of the rear end of the cover member 20 corresponding to the second engaged surface 39 of the slide member 30.

Figure 8 is an enlarged vertical cross-sectional view of the front end of the writing instrument set 1 in Figure 1, and Figure 9 is an enlarged vertical cross-sectional view of the writing instrument set 1 seen from an angle different from that of Figure 8. Figure 10 is an enlarged vertical cross-sectional view of the front end of the writing instrument set 1 in Figure 3, Figure 11 is an enlarged vertical cross-sectional view of the writing instrument set 1 seen from an angle different from that of Figure 10, and Figure 12 is an enlarged vertical cross-sectional view of the writing instrument set 1 in a position different from that of Figure 11.

Figures 1, 8 and 9 show the writing instrument set 1 in a stored state in which three ballpoint pens, that is, writing instruments 40, are stored. In the stored state, the slide member 30 is in a forward position within the case 2. Therefore, the rear end of the writing instrument 40 protrudes slightly from the open end of the case 2, to the extent that a user cannot grasp and remove the writing instrument 40. In this case, the rear end of the writing instrument 40 does not have to protrude.

Referring particularly to FIG. 9, when the writing instrument 40 is stored, the slide member 30 is engaged with the case 2 against the biasing force of the spring 51. In other words, when the slide member 30 is biased rearward, the first engaging surface 37 of the engaging piece 35 engages with the first engaged surface 25 of the cover member 20. This restricts the rearward movement of the slide member 30.

When the writing instrument 40 is stored, the operating unit 21 is operated to move the slide member 30 rearward, and the writing instrument 40 is removed. In this embodiment, the operation of the operating unit 21 means pressing the operating unit 21. When the operating unit 21 is pressed, the locking piece 35 pressed by the operating unit 21 bends inward, and the lock between the first locking surface 37 of the locking piece 35 and the first locked surface 25 of the cover member 20 is released. As a result, the biasing force of the spring 51 moves the slide member 30 rearward, and the writing instrument 40 is removed.

Figures 3, 10 to 12 show the writing instrument set 1 in a state in which the writing instrument 40 has been removed. In the removed state, the slide member 30 is in a retracted position within the case 2. Therefore, the rear end of the writing instrument 40 protrudes from the open end of the case 2, and the user can grasp and remove any writing instrument 40.

Referring particularly to FIG. 11, when the writing implement 40 is in the removed state, the slide member 30 is engaged with the case 2 against the further biasing force of the spring 51. That is, the slide member 30 is biased rearward, and the second engaging surface 39 engages with the second engaged surface 27 of the cover member 20. This restricts further rearward movement of the slide member 30. In other words, the rearward movement of the slide member 30 in the transition from the stored state to the removed state is stopped by the second engaging surface 39 of the slide member 30 colliding with the second engaged surface 27 of the cover member 20.

The rearward movement of the slide member 30 in the transition from the stored state to the removed state is braked by the frictional resistance between the inclined surface 38 and the protrusion 23 of the cover member 20. That is, while the slide member 30 is moving rearward, the inclined surface 38 of the slide member 30 and the protrusion 23 of the cover member 20 are always in contact. Furthermore, since the slide member 30 has an inclined surface 38 that inclines toward the rear, the further the slide member 30 moves rearward, the more the protrusion 23 of the cover member 20 is pressed against the inclined surface 38. As a result, the slide member 30 decelerates as it moves rearward, and the transition to the removed state is completed. This deceleration action prevents the slide member 30 from suddenly stopping due to a collision, thereby preventing damage to parts due to impact and the writing instrument 40 from unintentionally flying out of the case 2 due to inertia.

Referring to FIG. 12, when the writing implement 40 is removed, the locking piece 35 of the sliding member 30 is housed in the recess 26 of the cover member 20. That is, the inward bending of the locking piece 35 caused by the pressure of the operating part 21 is restored. In other words, in the stored and removed states, no unnecessary force is applied to the locking piece 35. Therefore, the locking piece 35 is prevented from being deformed for a long period of time, and plastic deformation of the locking piece 35 is prevented.

The operation unit may be operated not by pressing it but by performing another operation to change the storage state and removal state. For example, the operation unit may be configured to move the slide member 30 back and forth by sliding the operation unit in the forward and backward directions.

Each of the writing instruments 40 can be attached to and detached from the case 2 by engaging or disengaging the first engagement portion 45 of the writing instrument 40 and the case 2, i.e., the second engagement portion 34 of the slide member 30. That is, when the writing instrument 40 is inserted into the insertion hole 31 of the slide member 30, the first engagement portion 45 of the writing instrument 40 is pushed strongly into the second engagement portion 34. As a result, the first engagement portion 45 and the second engagement portion 34 are engaged with each other so that they cannot be removed with a light force. On the other hand, when the writing instrument 40 is removed from the case 2, the first engagement portion 45 of the writing instrument 40 is pulled strongly into the second engagement portion 34 again. As a result, the first engagement portion 45 and the second engagement portion 34 are disengaged.

In the writing instrument set 1, the first engaging portion 45 is provided on the writing part 42 side of the writing instrument 40 in the axial direction, particularly near the writing part 42, and the corresponding second engaging portion 34 is provided inside the case 2, which provides the effect that the engaging force does not decrease even if the writing instrument 40 is repeatedly attached and detached. In addition, the first engaging portion 45 and the second engaging portion 34 do not come into contact with other parts, etc., when the writing instrument 40 is repeatedly attached and detached, and therefore there is an effect that wear is unlikely to occur. Furthermore, by providing the first engaging portion 45 on the writing part 42 side of the writing instrument 40 in the axial direction, particularly near the writing part 42, there is also an effect that there are no restrictions on the shape of the writing instrument body 41 of the writing instrument 40 and no restrictions on the design, such as patterns.

The first and second engaging portions may have any configuration as long as they can achieve the above-mentioned effects and can engage and disengage with each other. For example, the first engaging portion 45 may be a plurality of protrusions evenly spaced along the circumferential direction, and the second engaging portion 34 may be an annular protrusion. Also, one of the first and second engaging portions may be a protrusion, and the other of the first and second engaging portions may be a recess corresponding to the protrusion.

Figure 14 is a front view of clip member 50, Figure 15 is a side view of clip member 50, Figure 16 is a cross-sectional view taken along line X-X in Figure 14, Figure 17 is a cross-sectional view taken along line Y-Y in Figure 15, and Figure 18 is an enlarged view of part A in Figure 16.

The clip member 50 is formed by deforming a single metal plate into a roughly U-shape. The clip member 50 has an attachment plate 51 that is attached to the side of the case body 10, and a gripping plate 52 that grips an item between the attachment plate 51. The rear end of the gripping plate 52 is formed with a bent portion 52a that is bent in a direction away from the attachment plate 51. The clip member 50 has the bent portion 52a, making it easy to insert an item such as paper between the attachment plate 51 and the gripping plate 52.

The front side of the gripping plate 52 is formed with a rounded rectangular opening 53 extending along the center line of the clip member 50. The mounting plate 51 is formed with a protrusion 54 that is exposed from the opening 53 and extends rearward along the center line from a position corresponding to the front end of the opening 53 beyond the rear end of the opening 53. The protrusion 54 is formed by forming a minute recess 51a on the opposite surface of the mounting plate 51, as shown in FIG. 17. The formation of the protrusion 54 on the mounting plate 51 increases the strength of the mounting plate 51 against deformation such as warping. Therefore, when the clip member 50 is attached to the case body 10, for example, when it is bonded, it is possible to prevent the mounting plate 51 from being deformed due to stress applied to the bonding surface.

18, the protrusion 54 of the mounting plate 51 and the gripping plate 52 are spaced apart near the rear end of the opening 53. Therefore, the protrusion 54 and the gripping plate 52 are not in contact with each other and are spaced apart along the length of the protrusion 54. In other words, the opening 53 is formed so that the protrusion 54 and the gripping plate 52 do not come into contact with each other, that is, to prevent contact. Therefore, the mounting plate 51 and the gripping plate 52 can be configured to be in close contact with each other so that an article can be firmly gripped at a location other than the opening 53 and the protrusion 54, for example, at the left and right edges of the protrusion 54 (the edges located above and below the protrusion 54 in FIG. 14). Furthermore, referring to the cross-sectional view shown in FIG. 17, since the protrusion 54 protrudes slightly into the opening 53, when a thin piece of paper or the like is gripped, the paper or the like is deformed to follow the shape of the protrusion 54, and the paper or the like can be gripped more firmly.

The protrusions 54 may be multiple, and may be arranged and shaped as desired on the mounting plate 51, so long as deformation of the mounting plate 51 is prevented. The corresponding openings 53 may be formed in any shape as long as they are formed so that the gripping plate 52 and the protrusions 54 do not come into contact with each other, and as long as the adhesion between the mounting plate 51 and the gripping plate 52 is ensured.

The material of the case 2, i.e., the case body 10 and the cover member 20, is preferably a hard plastic such as ABS or polycarbonate.

The material of the writing implement body 41 is a plastic material that is different from and softer than the material of the case 2. Specifically, it must be made of 50% or more by mass of polypropylene resin and must have a tensile modulus of elasticity (JIS K 7161:2014-1) of 70 MPa or more. Due to these characteristics, there is little resistance when rubbing the writing made with thermochromic ink to discolor or erase it, sufficient frictional heat can be obtained even with light pressure, and it is also possible to erase small details.

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

Other than the polypropylene resins, examples of resins that can be used include polyethylene and ionomers. In order to further enhance the effect, it is preferable that these resins be present in an amount of 0.5 to 30% by mass of the total shaft.

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

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

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

Furthermore, modified petroleum resins obtained by modifying petroleum resins made of the _C9 fraction are preferably used as resins that have both high adhesion and adhesion durability. Examples of modified petroleum resins include _C9- based petroleum resins modified with unsaturated alicyclic compounds, C9 _- based petroleum resins modified with compounds having hydroxyl groups, and C9 _- based petroleum resins modified with unsaturated carboxylic acid compounds. Preferred unsaturated alicyclic compounds include cyclopentadiene and methylcyclopentadiene, and examples of Diels-Alder reaction products of alkylcyclopentadiene include dicyclopentadiene, cyclopentadiene/methylcyclopentadiene codimers, and tricyclopentadiene, with dicyclopentadiene being particularly preferred. Dicyclopentadiene-modified _C9 -based petroleum resins can be obtained by thermal polymerization or the like in the presence of both dicyclopentadiene and the _C9 fraction. An example of a dicyclopentadiene-modified _C9 petroleum resin is Neopolymer 130S manufactured by JX Nippon Oil & Energy Corporation.

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

Hydroxyl-containing _C9 petroleum resins can also be produced by a method in which an alkyl (meth)acrylate ester or the like is thermally polymerized together with a petroleum fraction to introduce an ester group into the petroleum resin, and then the ester group is reduced; or a method in which a double bond is left or introduced into the petroleum resin, and then the double bond is hydrated.

As the hydroxyl group-containing _C9 petroleum resin, those obtained by various methods as described above can be used, but in terms of performance and production, it is preferable to use phenol-modified petroleum resin, etc., which is obtained by cationic polymerization of a _C9 fraction in the presence of phenol, is easy to modify, and is low-cost. An example of the phenol-modified _C9 petroleum resin is Neopolymer-E-130 manufactured by JX Nippon Oil & Energy Corporation.

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

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

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

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

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

In addition to the polypropylene resins and the like, the resins used for adjusting the adhesiveness may contain optional components such as heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents, antiblocking agents, sealability improvers, release agents (e.g., stearic acid, silicone oil, etc.), lubricants such as polyethylene wax, colorants, pigments, inorganic fillers (e.g., alumina, talc, calcium carbonate, mica, varastenit, clay, etc.), foaming agents (organic, inorganic), antibacterial agents (e.g., imidazole, phenol, silver, etc.), and flame retardants (e.g., hydrated metal compounds, red phosphorus, ammonium polyphosphate, antimony compounds, silicone, etc.) in appropriate amounts, as desired, within the scope of the effect. The shaft material may also contain alkylsulfonic acid phenyl esters and cyclohexanedicarboxylate esters. By including alkylsulfonic acid phenyl ester and cyclohexanedicarboxylate in the shaft, it is possible to erase handwriting without damaging the paper surface or blurring the printed characters. The pen can be manufactured by a method such as extrusion molding or injection molding using the above-mentioned polypropylene resin.

When imparting durability, in order to exert the effect, it is necessary that the tensile modulus (JIS K 7161:2014-1) is 70 MPa or more, and preferably 80 to 5000 MPa. If this tensile modulus is less than 70 MPa, the effect cannot be exerted, which is not preferable. To make the tensile modulus of this shaft 70 MPa or more, it can be adjusted by appropriately combining the type and amount of polypropylene resin used, the other resin types, and their contents, etc.

More preferably, in order to further exert the effect and reduce the sense of resistance, the permanent elongation of the shaft (JIS K6273:2006) is 50% or more, and particularly preferably 50 to 100%. The "permanent elongation" defined here is the value (%) obtained by dividing the elongated length by the length before elongation after the test piece is stretched to twice its original length and held at 23°C for six hours.

As described above, the refill 2 may be a refill that contains a thermochromic ink that contains a thermochromic coloring material. In this case, the writing instrument 40 is a thermochromic writing instrument, and the writing instrument body 41 may be a friction body that serves as an erasing member. Handwriting made with the writing instrument 40 can be thermochromic due to frictional heat generated when rubbed against the writing instrument body 41, for example, the rear end of the writing instrument body 41 or the tapered portion near the writing part 42.

Here, thermochromic ink refers to ink that has the property of maintaining a predetermined color (first color) at room temperature (e.g., 25°C), changing to another color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returning to the original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In a double-ended writing instrument 1 using thermochromic ink, the second color is made colorless, and the term "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Thus, the line is rubbed against the writing surface on which it was drawn with a friction body to generate frictional heat, which changes the drawn line to colorless, i.e., erases it. Of course, the second color may be a color other than colorless.

The thermochromic microencapsulated pigment that serves as the thermochromic coloring material is not particularly limited as long as it has the ability to change color due to heat such as frictional heat, for example, from colored to colorless, from colored to colored, or from colorless to colored, and various types can be used, and examples of such materials include microencapsulated thermochromic compositions that contain at least a leuco dye, a color developer, and a color change temperature regulator.

The leuco dyes that can be used are not particularly limited, so long as they are electron-donating dyes that function as color-developing agents. Specifically, in order to obtain inks with excellent color-developing properties, triphenylmethane-based, spiropyran-based, fluoran-based, diphenylmethane-based, rhodamine lactam-based, indolylphthalide-based, leucoauramine-based, etc. can be used alone (one type) or in a mixture of two or more types (hereinafter simply referred to as "at least one type").

Specifically, 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]-1(3H)-isobenzofuranone, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)- 4-Azaphthalide, 1,3-dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-dimethylaminofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 2-(2-chloroanilino)-6-dibutylaminofluoran, 3,6-dimethoxyfluoran, 3,6-di -n-butoxyfluoran, 1,2-benz-6-diethylaminofluoran, 1,2-benz-6-dibutylaminofluoran, 1,2-benz-6-ethylisoamylaminofluoran, 2-methyl-6-(N-p-tolyl-N-ethylamino)fluoran, 2-(N-phenyl-N-methylamino)-6-(N-p-tolyl-N-ethylamino)fluoran, 2-(3'-trifluoromethylanilino)-6-diethylamino Nofluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 3-di(n-butyl)amino-6-methoxy-7-anilinofluoran, 3,6-bis(diphenylamino)fluoran, methyl-3',6'-bisdiphenylaminofluoran, chloro-3',6'-bisdiphenylaminofluoran, 3-methoxy-4-dodecoxystyrinoquinoline, etc.

These leuco dyes have a lactone skeleton, a pyridine skeleton, a quinazoline skeleton, a bisquinazoline skeleton, etc., and color is generated by opening these skeletons (rings).

The color developer that can be used is a component that has the ability to cause the leuco dye to develop color, and examples of such compounds include phenolic resin compounds, salicylic acid metal chlorides, salicylic acid resin metal salt compounds, and solid acid compounds.

Specifically, o-cresol, tertiary butyl catechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, hexafluorobisphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcinol, dodecyl gallate, 2,2-bis(4'-hydroxyphenyl)propane, 4,4-dihydroxydiphenyl sulfone, 1,1-bis(4'-hydroxyphenyl)ethane, 2,2-bis(4'-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)sulfide, 1-phenyl-1,1-bis( 1,1-bis(4'-hydroxyphenyl)ethane, 1,1-bis(4'-hydroxyphenyl)-3-methylbutane, 1,1-bis(4'-hydroxyphenyl)-2-methylpropane, 1,1-bis(4'-hydroxyphenyl)n-hexane, 1,1-bis(4'-hydroxyphenyl)n-heptane, 1,1-bis(4'-hydroxyphenyl)n-octane, 1,1-bis(4'-hydroxyphenyl)n-nonane, 1,1-bis(4'-hydroxyphenyl)n-decane, 1 , 1-bis(4'-hydroxyphenyl)n-dodecane, 2,2-bis(4'-hydroxyphenyl)butane, 2,2-bis(4'-hydroxyphenyl)ethyl propionate, 2,2-bis(4'-hydroxyphenyl)-4-methylpentane, 2,2-bis(4'-hydroxyphenyl)hexafluoropropane, 2,2-bis(4'-hydroxyphenyl)n-heptane, 2,2-bis(4'-hydroxyphenyl)n-nonane, etc. are at least one of them.

The amount of developer used can be selected according to the desired color density and is not particularly limited, but it is usually preferable to select an amount within the range of about 0.1 to 100 parts by weight per 1 part by weight of the leuco dye described above.

The discoloration temperature regulator that can be used is a substance that controls the discoloration temperature in the color development of the leuco dye and the color developer. Specific examples of discoloration temperature regulators that can be used include alcohols, esters, ketones, ethers, acid amides, azomethines, fatty acids, and hydrocarbons.

More specifically, at least one of bis(4-hydroxyphenyl)phenylmethane dicaprylate (C ₇ H ₁₅ ), bis(4-hydroxyphenyl)phenylmethane dilaurate (C ₁₁ H ₂₃ ), bis(4-hydroxyphenyl)phenylmethane dimyristate (C ₁₃ H ₂₇ ), bis(4-hydroxyphenyl)phenylethane dimyristate (C ₁₃ H ₂₇ ), bis(4-hydroxyphenyl)phenylmethane dipalmitate (C ₁₅ H ₃₀ ), bis(4-hydroxyphenyl)phenylmethane dibehenate (C ₂₁ H ₄₃ ), bis(4-hydroxyphenyl)phenylethylhexylidene dimyristate (C ₁₃ H ₂₇ ) and the like can be mentioned.

The amount of the discoloration temperature regulator used can be appropriately selected depending on the desired hysteresis width and color density at the time of color development, and is not particularly limited, but it is usually preferable to use it in the range of about 1 to 100 parts by weight per 1 part by weight of the leuco dye.

The thermochromic microencapsulated pigment can be produced by microencapsulating a thermochromic composition containing at least the above leuco dye, color developer, and color change temperature regulator so that the average particle size is 0.2 to 5 μm. Examples of microencapsulation methods include interfacial polymerization, interfacial polycondensation, in situ polymerization, liquid curing coating, phase separation from an aqueous solution, phase separation from an organic solvent, melt dispersion cooling, air suspension coating, and spray drying, and can be appropriately selected depending on the application.

For example, in the phase separation method from an aqueous solution, the leuco dye, developer, and discoloration temperature regulator are heated and melted, then added to an emulsifier solution, heated and stirred to disperse them into oil droplets, and then a resin raw material is gradually added as a capsule membrane agent, such as an amino resin solution or an isocyanate resin solution, and the mixture is allowed to react and then filtered to produce the desired thermochromic microcapsule pigment.

The content of these leuco dyes, color developers, and color change temperature regulators varies depending on the type of leuco dyes, color developers, and color change temperature regulators used, the microencapsulation method, etc., but the mass ratio is 0.1 to 100 parts of color developer and 1 to 100 parts of color change temperature regulator per 1 part of the dye. The mass ratio of the capsule membrane agent to the capsule contents is 0.1 to 1.

The thermochromic microcapsule pigment can be set to an appropriate temperature for each color's color development temperature (for example, color development at 0°C or higher) and color loss temperature (for example, color loss at 50°C or higher) by appropriately combining the types and amounts of the above-mentioned leuco dye, color developer, and color change temperature regulator, and it is preferable that the color changes from colored to colorless due to heat such as frictional heat.

In the case of thermochromic microcapsule pigments, in order to further improve the line density, storage stability, and writing ability, it is preferable that the wall film is formed of a urethane resin, a urea/urethane resin, an epoxy resin, or an amino resin. Examples of urethane resins include compounds of isocyanate and polyol. Examples of epoxy resins include compounds of epoxy resin and amine. Examples of amino resins include melamine resin, urea resin, and benzoguanamine resin. The thickness of the wall film of the microcapsule color material is appropriately determined depending on the required wall film strength and line density.

The average particle diameter of the thermochromic microencapsulated pigment is preferably 0.2 to 5 μm, and more preferably 0.3 to 3 μm, from the standpoints of colorability, color development, ease of fading, stability, fluidity in the ink, suppression of adverse effects on writing, and compatibility with the photochromic microencapsulated pigment described below. The "average particle diameter" specified here is the value obtained by measuring the average particle diameter (50% diameter) (refractive index 1.8) using a particle size analyzer [Microtrac HRA9320-X100 (manufactured by Nikkiso)].

If the average particle size is less than 0.2 μm, sufficient line density cannot be obtained, while if it exceeds 5 μm, it is undesirable because it deteriorates writing properties, reduces the dispersion stability of the thermochromic microencapsulated pigment, and is prone to ink back caused by vibration. Furthermore, the 90% diameter is 8 μm or less, preferably 6 μm or less. If a certain proportion of particles with large diameters are present, the above-mentioned effects tend to become more pronounced. Note that the microencapsulated pigment that falls within the above-mentioned average particle size range (0.2 to 5 μm) varies depending on the microencapsulation method, but in a phase separation method from an aqueous solution, it can be prepared by appropriately combining the stirring conditions when manufacturing the microencapsulated pigment.

The specific gravity of the thermochromic microencapsulated pigment is in the range of 0.9 to 1.3, preferably 1.0 to 1.2. If the specific gravity is outside this range, the dispersion stability of the microencapsulated pigment is likely to decrease. Furthermore, microencapsulated pigments with a specific gravity exceeding 1.3 are prone to ink back caused by vibration.

In addition to the thermochromic microencapsulated pigment, the aqueous ink composition for writing instruments may contain water (tap water, purified water, distilled water, ion-exchanged water, pure water, etc.) as the solvent as the remainder, and may also contain water-soluble organic solvents, thickeners, lubricants, rust inhibitors, preservatives, or antibacterial agents as appropriate, within the scope of not impairing the effects of the agent, depending on the intended use of the writing instrument (ballpoint pen, marking pen, etc.).

Examples of water-soluble organic solvents that can be used include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 3-butylene glycol, thiodiethylene glycol, and glycerin, as well as ethylene glycol monomethyl ether and diethylene glycol monomethyl ether, which can be used alone or in combination.

Of these, it is preferable to use glycerin to prevent the ink from solidifying at the writing area due to the ink bag, and the amount added is preferably 1 to 10% by mass of the total amount of ink, which is thought to have the effect of reducing the cohesive force between the pigment and ink components in a dry state.

As the thickener that can be used, for example, at least one selected from the group consisting of synthetic polymers, cellulose, and polysaccharides is preferable. Specific examples include gum arabic, tragacanth gum, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, xanthan gum, welan gum, succinoglycan, diutan gum, dextran, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, starch glycolic acid and its salts, propylene glycol alginate, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyacrylic acid and its salts, carboxyvinyl polymer, polyethylene oxide, copolymer of vinyl acetate and polyvinylpyrrolidone, crosslinked acrylic acid polymer and its salts, non-crosslinked acrylic acid polymer and its salts, styrene acrylic acid copolymer and its salts, etc.

Of these, it is preferable to use polysaccharides. Due to their rheological properties, polysaccharides tend to be less susceptible to the effects of vibration on fluidity, and are less likely to cause problems such as poor writing caused by ink bag. Xanthan gum is particularly preferable, as it provides an excellent balance with other properties required of writing instrument inks.

Lubricants include fatty acid esters of polyhydric alcohols, which are also used as surface treatment agents for pigments, higher fatty acid esters of sugars, polyoxyalkylene higher fatty acid esters, alkyl phosphate esters, alkyl sulfonates of higher fatty acid amides, alkyl aryl sulfonates, polyalkylene glycol derivatives, fluorine-based surfactants, polyether-modified silicones, etc. Rust inhibitors include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, saponins, etc. Preservatives or antibacterial agents include phenol, sodium omadine, sodium benzoate, benzimidazole-based compounds, etc.

This aqueous ink composition for writing instruments can be produced by a conventional method, for example, by blending the thermochromic and photochromic microencapsulated pigments and the other aqueous components in predetermined amounts and stirring and mixing them with a stirrer such as a homomixer or a disperser. If necessary, coarse particles in the ink composition may be removed by filtration or centrifugation.

The viscosity value of the aqueous ink composition for writing instruments is preferably 500 to 2000 mPa·s at 25° C. and a shear rate of 3.83/s, and 20 to 100 mPa·s at a shear rate of 383/s. By setting the viscosity within the above range, an ink having excellent writing properties and stability over time can be obtained. Furthermore, the non-Newtonian viscosity index n calculated by the viscosity formula S=αD ⁿ (where 1>n>0) (S is shear stress (dyn/cm ² ), D is shear rate (s ⁻¹ ), and α is a non-Newtonian viscosity coefficient) is preferably 0.2 to 0.6. By setting the non-Newtonian viscosity index n within the above range in addition to the above viscosity range, it is possible to appropriately set the fluidity of the ink against vibration, and it is possible to prevent the occurrence of ink back.

The surface tension of the aqueous ink composition for writing instruments is preferably 25 to 45 mN/m, and more preferably 30 to 40 mN/m. Within this range, the balance between the wettability of the inside of the pen tip and the ink is appropriate, making it possible to prevent the occurrence of ink back.

In the refill, an ink follower may be placed immediately behind the ink. The material constituting the follower may be composed of at least a non-volatile or low-volatility organic solvent and a thickener. The non-volatile or low-volatility organic solvent used in the ink follower is used as the base oil of the ink follower, and liquid paraffin is used, for example. Mineral oil and chemically synthesized oil are used for the liquid paraffin, and polybutene, poly-α-olefin, ethylene α-olefin oligomer, etc. can be used as the chemically synthesized oil.

Specific examples of mineral oils that can be used include commercially available Diana Process Oil NS-100, PW-32, PW-90, NR-68, and AH-58 (manufactured by Idemitsu Kosan Co., Ltd.).

Specific examples of polybutenes that can be used include commercially available products such as Nissan Polybutene 200N, Polybutene 30N, Polybutene 10N, Polybutene 5N, Polybutene 3N, Polybutene 015N, Polybutene 06N, and Polybutene 0N (all manufactured by Nippon Oil & Fats Corporation), Polybutene HV-15 (manufactured by Nippon Petrochemical Industry Co., Ltd.), and 35R (manufactured by Idemitsu Kosan Co., Ltd.).

Specific examples of poly-α-olefins that can be used include commercially available barrel process oils P-26, P-46, P-56, P-150, P-350, P-1500, P-2200, (P-10000, P-37500) (manufactured by Matsumura Oil Co., Ltd.).

Specific examples of ethylene α-olefin oligomers that can be used include commercially available products such as LUCANT HC-10, HC-20, HC-100, HC-150, (HC-600, HC-2000) (all manufactured by Mitsui Chemicals, Inc.).

These non-volatile or low-volatile organic solvents can be used alone or in combination of two or more.

Examples of thickeners used in the ink follower include calcium salts of phosphate esters, fine silica particles, block copolymers of polystyrene-polyethylene/butylene rubber-polystyrene, block copolymers of polystyrene-polyethylene/propylene rubber-polystyrene, hydrogenated styrene-butadiene rubber, block copolymers of styrene-ethylenebutylene-olefin crystals, block copolymers of olefin crystals-ethylenebutylene-olefin crystals, and acetoalkoxyaluminum dialkylates, and these may be used alone or in combination of two or more.

Preferred commercially available calcium salts of phosphate esters that can be used include Crodax DP-301LA (manufactured by Croda Japan Co., Ltd.). Usable fine particle silica includes hydrophilic fine particle silica and hydrophobic fine particle silica. Preferred commercially available hydrophilic silica products include AEROSIL-300 and AEROSIL-380 (manufactured by Nippon Aerosil Co., Ltd.), and preferred commercially available hydrophobic silica products include AEROSIL-974D and AEROSIL-972 (manufactured by Nippon Aerosil Co., Ltd.).

Preferable commercially available polystyrene-polyethylene/butylene rubber-polystyrene block copolymers include Kraton GFG-1901X and Kraton GG-1650 (both manufactured by Shell Japan), Septon 8007 and Septon 8004 (both manufactured by Kuraray Co., Ltd.), etc. Preferable commercially available polystyrene-polyethylene/propylene rubber-polystyrene block copolymers include Kraton GG-1730 (manufactured by Shell Japan), Septon 2006 and Septon 2063 (both manufactured by Kuraray Co., Ltd.), etc.

Preferred commercially available hydrogenated styrene-butadiene rubbers include DYNARON 1320P, DYNARON 1321P (both manufactured by JSR Corporation), Tuftec H1041, and Tuftec H1141 (both manufactured by Asahi Chemical Industry Co., Ltd.).

Preferred commercially available styrene-ethylenebutylene-olefin crystalline block copolymers include DYNARON 4600P (manufactured by JSR Corporation), and preferred commercially available olefin crystalline-ethylenebutylene-olefin crystalline block copolymers include DYNARON 6200P and DYNARON 6201B (manufactured by JSR Corporation).

Preferred commercially available acetoalkoxyaluminum dialkylates include PLENACT AL-M (manufactured by Ajinomoto Fine-Techno Co., Ltd.).

Among these thickeners, it is preferable to use thermoplastic olefin-based elastomers such as styrene-ethylenebutylene-olefin crystal block copolymers and olefin crystal-ethylenebutylene-olefin crystal block copolymers in order to further enhance the effect.

Furthermore, in order to obtain an ink follower that prevents the occurrence of ink back, it is preferable that the average tan δ value measured for each frequency while exponentially increasing in the frequency range of 1 to 63 rad/s is 1.0 or more, and more preferably 1.7 to 3.4.

Here, tan δ is a value that means the loss modulus/storage modulus, and it has been known in the past that the average tan δ value measured for each frequency while exponentially increasing in the frequency range "1 to 63 rad/s" is preferably 1.0 or less. Here, by making the average tan δ value measured for each frequency in the above 1 to 63 rad/s 1.0 or more, it becomes possible to absorb vibrations and prevent the occurrence of ink back.

1 Writing set 2 Case 2
REFERENCE SIGNS LIST 10 Case body 11 Holding protrusion 20 Cover member 30 Slide member 34 Second engagement portion 40 Writing implement 42 Writing portion 45 First engagement portion 50 Clip member 51 Spring

Claims (2)

A writing instrument set comprising a plurality of writing instruments and a case capable of storing the plurality of writing instruments in an aligned state,
Each of the writing instruments is detachable from the case;
Each of the plurality of writing instruments has a writing instrument body that is a cylindrical member formed in a cylindrical shape, the plurality of writing instruments include a thermochromic writing instrument and a non-thermochromic writing instrument, the bending modulus of the writing instrument body of the thermochromic writing instrument differs from the bending modulus of the writing instrument body of the non-thermochromic writing instrument by 300 MPa or more,
The plurality of writing instruments include at least two writing instruments containing different achromatic inks, the writing instrument body of the writing instrument having a darker line density of the achromatic ink is black, and the writing instrument body of the writing instrument having a lighter line density of the ink is a color other than black. A clip member is attached to the side surface of the opening end of the case,
The clip member is a metal plate member formed in a substantially U-shape,
The clip member has an attachment plate and a gripping plate that grips an article between the attachment plate and the gripping plate,
The gripping plate has an opening formed therein,
The writing instrument set according to claim 1, characterized in that the mounting plate is formed with a protrusion that is exposed from the opening and extends rearward along the center line from a position corresponding to the front end of the opening to beyond the rear end of the opening.

Images