JP7357461B2 - Ballpoint pen refills and ballpoint pens - Google Patents

Description

The present invention relates to a ballpoint pen refill and a ballpoint pen.

A ballpoint pen tip for holding a writing ball is usually formed by the following steps.
First, a ball house in which a writing ball is housed is cut from the tip end of a holder made of a cylindrical material.

Subsequently, a back hole is cut from the rear end of the holder to serve as a flow path for guiding the ink inside the ballpoint pen to the tip.
Then, these ball houses and back holes are penetrated by cutting or the like to form ink holes. This ink hole becomes a flow path that guides the ink that has reached the back hole further toward the tip side.

Next, a plurality of grooves are cut radially around the ink hole. This groove is a channel groove. This channel groove becomes a flow path that guides the ink that has reached the ink hole to the ball house.

After the writing ball is inserted into the ball house, it is struck and pressed toward the rear end. This process is called "tataki". This tapping transfers the curved surface of the writing ball onto the bottom of the ball house. The curved surface of the bottom of this ball house serves as a ball catch.
Finally, by caulking the tip of the holder inward, a caulking part is formed to prevent the writing ball from falling off.

Patent Document 1 discloses a ballpoint pen refill using a so-called ultra-fine ballpoint pen tip with a writing ball diameter of 0.45 mm or less, and a ballpoint pen using the ballpoint pen refill.

JP2015-208932A

Here, a relatively small ballpoint pen tip with a writing ball diameter of 0.45 mm or less has a smaller ballpoint tip due to its smaller ball diameter than a ballpoint pen tip with a writing ball diameter of 0.5 mm or 0.7 mm. The wall thickness at the tip is thinner, so it is more susceptible to impact when dropped from a desk to the floor. Specifically, the tip of the ballpoint pen tip is dented due to the impact caused by the drop, and the dent reduces the amount of ink supplied, resulting in blurred lines when writing.

In view of the above problem, it is possible to increase the thickness of the tip of the ballpoint pen tip, but if the thickness of the tip of the ballpoint pen tip is made thicker than necessary, the caulked part will easily get caught on the writing surface when writing. , a new problem arises, that is, a decrease in writing feel.

Therefore, an object of the present invention is to increase the drop resistance of a ballpoint pen tip while suppressing the deterioration in writing feel when a ballpoint pen tip having a writing ball diameter of 0.35 to 0.45 mm is used.

In order to solve the above problems, embodiments of the present invention include the following configuration.
(1) First Embodiment The ballpoint pen refill according to the first embodiment of the present invention includes a writing ball having a diameter of 0.45 mm or less, a cylindrical body portion that holds the writing ball, a holder having a tapered portion formed tapered at the tip side of the body portion; a ball house formed from the tip of the tapered portion toward the rear end of the tapered portion and housing the writing ball; A ball receiving seat which is the bottom surface of the ball house and has the curved surface of the writing ball transferred thereto, and a back which is an internal space that is formed from the rear end of the holder toward the tip of the holder and reaches the vicinity of the ball house. an ink hole that is an internal space formed to communicate between the hole, the ball house and the back hole, and an ink hole that is equally distributed around the ink hole and that connects the ink hole and the ball house. a ballpoint pen tip comprising a channel groove, which is a plurality of grooves formed in such a way that the tip of the tapered part is caulked inward, and an ink containing oil-based ink and to which the ballpoint pen tip is attached. a storage tube, the caulking outer diameter, which is the outer diameter at the tip surface of the caulking part, is less than 112% of the writing ball diameter, and the distance from the outermost edge of the bottom surface of the ball house to the tapered part The radial thickness of the holder is 23% or more and less than 40% of the writing ball diameter.

(2) Second Embodiment The ballpoint pen refill according to the second embodiment of the present invention is the ballpoint pen refill according to the first embodiment, in which the ballpoint pen refill from the tip of the writing ball in the state accommodated in the ball house, The length along the axis of the ballpoint pen tip up to the rear end of the tapered portion is less than 4 mm.

(3) Third Embodiment The ballpoint pen refill according to the third embodiment of the present invention is the ballpoint pen refill according to the first or second embodiment, in which the tapered portion The angle formed by the line segment extending is 30° or more and less than 50°.

(4) Fourth embodiment The ballpoint pen refill according to the fourth embodiment of the present invention is the ballpoint pen refill according to the first, second, or third embodiment, and the outer diameter of the body is 2.35 mm. or more, and less than 2.6 mm.

(5) Fifth Embodiment A ballpoint pen according to a fifth embodiment of the present invention includes a barrel, and the ballpoint pen refill of the first, second, third, or fourth embodiment is accommodated in the barrel. Ta.

According to an embodiment of the present invention, when using a so-called ultra-fine ballpoint pen tip with a writing ball diameter of 0.45 mm or less, it is possible to suppress a decrease in writing feel and increase the drop resistance of the ballpoint pen tip. .

FIG. 1 is a front view of a ballpoint pen according to the present embodiment. They are a front view (A) and an II sectional view (B) of (A) of a ballpoint pen refill according to the present embodiment. FIG. 2 is a cross-sectional view of a ballpoint pen tip according to the present embodiment. 2 is a plan view showing the bottom surface of the ball house according to the present embodiment. FIG. 2 is a cross-sectional view of the tip of the ballpoint pen tip according to the present embodiment. FIG. 3 is a cross-sectional view of the tip of a ballpoint pen tip according to a comparative configuration. It shows the length of the tapered part according to the diameter of the writing ball.

This embodiment will be described with reference to the drawings. In addition, in the following description, the "tip side" refers to one side in the axial direction of the ballpoint pen 5 toward the tip shaft 11, which will be described later, and the "rear end side" refers to the other side toward the rear shaft 12, which will be described later. means.

(1) Ballpoint pen 5
As shown in FIG. 1, the ballpoint pen 5 includes, as its external structure, a shaft tube 10 having openings at each of its tip and rear ends. This barrel 10 has a front shaft 11 located on the axially distal end side and whose distal end portion is tapered, and a rear shaft 12 located on the rear end side of the front shaft 11, which are screwed together. It is formed. Note that a clip 13 is attached to the side surface of the rear shaft 12. A spring (not shown) is housed between the rear inner surface of the clip 13 and the rear shaft 12, and by pressing the rear end of the clip 13 toward the shaft center, the tip of the clip 13 is lifted, and the paper surface etc. can be easily pinched. Further, by setting the total weight of the ballpoint pen 5 to 30 g or more, it is possible to create a sense of luxury and weight in writing.

A tip opening 14 is formed at the tip of the tip shaft 11 to expose the ballpoint pen tip 40 of the ballpoint pen refill 20. Further, a rear end opening (not shown) is also formed at the rear end of the rear shaft 12, and a hollow dome-shaped cap member 15 is attached through this rear end opening. Note that a spherical decorative member 16 is fixed to the cap member 15 as an operation portion for causing the ballpoint pen refill 20 to protrude and retract from the tip of the tip barrel 11. The spherical decorative member 16 allows the ballpoint pen refill 20 to move in and out of the tip opening 14 of the barrel 10 by rotating in the circumferential direction about the axis. Note that, in order to facilitate operation, the decorative member 16 has a vertical groove 17 formed thereon that is visible along the axial direction. Incidentally, instead of the vertical grooves 17, the surface may have a satin finish.

In addition, the materials of the shaft tube 10, clip 13, cap member 15, and decorative member 16 contain metal components, and a diamond-like carbon film (DLC) coating is formed on the surface to improve wear resistance. , it can withstand long-term use like the ballpoint pen refill 20. The thickness of the DLC film is preferably 0.5 to 5 μm.

(2) Ballpoint pen refill 20
As shown in FIG. 2, the ballpoint pen refill 20 is an ink storage tube containing an oil-based ink 35 whose main solvent is other than water and has an ink viscosity of 10 to 3,000 mPa·s at a shear rate of 38.3 (s ⁻¹ ). 30, and a ballpoint pen tip 40 attached to the tip of the ink storage tube 30.

As shown in FIG. 2A, the ink storage tube 30 includes a substantially cylindrical large-diameter storage section 31 that accommodates the oil-based ink 35, and a small-diameter extension section 32 extending from the tip of the storage section 31. , is equipped with. By providing the large-diameter accommodating portion 31, more oil-based ink 35 can be accommodated than in conventional ink accommodating tubes, and writing is possible at a distance of at least 1500 m or more, more preferably 2000 m or more. A tail plug 33, which is a plug for preventing the oil-based ink 35 from flowing out, is attached to an opening at the rear end of the storage portion 31. Further, a ballpoint pen tip 40 is attached to the opening at the tip of the extending portion 32. The ink storage tube 30 is made of metal and has an inner surface that comes into contact with the oil-based ink 35 and has an arithmetic mean roughness of Ra of 0.5 μm or more according to JIS B0601. Preferably, the silicone oil is baked and solidified as a deposit. This type of baking process will ensure that the problem of ink and follower flowing out over time, and the problem of reversal of ink flowing diagonally when some of the ink remains on the wall while writing and the follower switches to the pen tip side, can be avoided. can be prevented.

Furthermore, as shown in FIG. 2(B), inside the accommodating portion 31, the above-mentioned oil-based ink 35 and an ink follower 34, which is a grease-like substance, are placed on the rear end side of the oil-based ink 35. Filled. This ink follower 34 plays the role of a plug for preventing the oil-based ink 35 from flowing out from the rear end of the ink storage tube 30, similar to the tail plug 33 described above. The ink follower 34 contains one or more poly-α-olefins, which are synthetic oils with a viscosity of 200 mPa·s or more at 40°C, the total amount of which is 80% by mass or more of all components, and It is preferable that the viscosity is 1000 to 40,000 mPa·s, the shear thinning index is 0.95 or more at a shear rate of 1 to 10 s ⁻¹ , and it does not contain a shear thinning agent.

(3) Ballpoint pen tip 40
Next, the ballpoint pen tip 40 will be explained using FIGS. 3 to 5.
As shown in FIG. 3, the ballpoint pen tip 40 includes a holder 50 that is formed by cutting a cylindrical material made of bismuth-containing ferritic stainless steel with a Vickers hardness of 200 or more and less than 450, and a holder 50 that is attached to the tip of the holder 50. It includes a writing ball 42 made of hard metal and having a diameter of 0.38 mm, and a pressing spring 44 fitted inside a holder 50.

The holder 50 includes, in order from the distal end thereof, a tapered portion 51, a body portion 52, and an insertion portion 53.

The tapered portion 51 is a member constituting the distal end portion of the holder 50, and has a conical shape that tapers toward the distal end side. A caulked portion 54 is formed at the tip of the tapered portion 51. The caulked portion 54 is caulked (deformed by pressing) so as to reduce the diameter inward (see FIG. 5). This caulking portion 54 holds the writing ball 42, and a portion of the writing ball 42 is exposed from the tip of the caulking portion 54 (see FIG. 5).

The body portion 52 is a member that is continuous with the rear end of the tapered portion 51 and constitutes the center portion of the holder 50, and has an outer diameter D of 2.5 mm. Note that the trunk outer diameter D is not limited to 2.5 mm, as long as it is 2.35 mm or more and less than 2.6 mm.

The insertion portion 53 is a member that is continuous with the rear end of the body portion 52 and constitutes the rear end portion of the holder 50, and has an outer diameter smaller than the outer diameter of the body portion 52. The insertion portion 53 plays the role of fixing the ballpoint pen tip 40 to the ink storage tube 30 by being press-fitted into the ink storage tube 30 from the opening at the tip of the extension portion 32 (see FIG. 2). .

Here, a ball house 55 for accommodating the writing ball 42 is formed at the tip of the tapered portion 51, that is, at the tip of the holder 50, from the tip of the holder 50 toward the rear end (FIG. reference). For example, this ball house 55 is formed by cutting with a drill.

A back hole 56, which is an internal space formed from the rear end of the holder 50 toward the front end, is formed inside the holder 50. This back hole 56 has a diameter that gradually decreases toward the tip side, and the tip reaches the vicinity of the ball house 55. For example, the back hole 56 is formed by cutting with a drill.

Then, by piercing the ball house 55 and the back hole 56 with a drill, an ink hole 57, which is an internal space communicating between the ball house 55 and the back hole 56, is formed (see FIG. 5). . That is, the ball house 55 and the back hole 56 communicate with each other via the ink hole 57.

Further, a coiled pressing spring 44 is inserted into the back hole 56 . After the pressing spring 44 is inserted, a plurality of locations around the insertion portion 53 are punched to form a protrusion 58 that protrudes inward. The rear end portion of the pressing spring 44 is supported by these projections 58.

On the other hand, the tip end portion of the pressing spring 44 is formed as a pressing rod 46 that extends straight toward the tip side and presses the writing ball 42 toward the tip side. The tip of the pressing rod 46 passes through the ink hole 57 and contacts the rear end of the writing ball 42 in the ball house 55. The load with which this pressing rod 46 presses the writing ball 42 toward the tip side is preferably greater than 0N and less than the total weight of the ballpoint pen 5, and more preferably 0.01N to 0.09N. Here, if this load is less than 0.01N, the writing ball 42 and the caulked portion 54 are not in close contact with each other when not writing, so the inside of the ball house 55 tends to dry. As a result, the line drawn at the beginning of writing tends to become blurred. On the other hand, if this load exceeds 0.09N, the writing ball 42 will be difficult to be pushed back even if writing pressure is applied, and the writing quality will be impaired. Therefore, in this embodiment, this load is set to 0.06 to 0.08N.

As shown in FIG. 4, on the ball house bottom surface 59, which is the bottom surface of the ball house 55, there is a ball receiving seat 60 on which the curved surface of the writing ball 42 is transferred by a tapping process in which the writing ball 42 is pressed toward the rear end after insertion. is formed.

Further, from the bottom surface 59 of the ball house, there are formed channel grooves 61, which are a plurality of grooves that are equally distributed around the ink hole 57 and are formed so as to communicate the ink hole 57 and the ball house 55. The channel groove 61 is formed by radially cutting four locations around the ink hole 57 using a channel cutting tool. The channel groove 61 has a structure to ensure the flow of ink between the ink hole 57 and the ball house 55 when the writing ball 42 is in contact with the ball receiving seat 60.

Here, the outermost portion of the ball house bottom surface 59 shown in FIG. 5 is referred to as the "outermost edge 62." In this embodiment, as shown in FIG. 5, the radial thickness X from the outermost edge 62 to the tapered portion 51 is 23% or more of the diameter of the writing ball 42 (the diameter of the writing ball 42), and It is less than %. As mentioned above, the diameter of the writing ball 42 is 0.38 mm, but in this embodiment, the thickness X is 98 μm. That is, in this embodiment, the thickness X is 25% of the diameter of the writing ball 42.

Further, although FIG. 5 shows a cross section passing through the axis S of the ballpoint pen tip 40, in this embodiment, the taper angle T, which is the angle formed by the line segment extending the tapered portion 51, is 30 The angle is greater than or equal to 50° and less than 50°, specifically 35°.

(4) Effects As described above, in this embodiment, the radial thickness X from the outermost edge 62 to the tapered portion 51 is 23% or more and less than 40% of the diameter of the writing ball 42. , specifically, 98 μm (see FIG. 5). That is, in this embodiment, the thickness X is 25% of the diameter of the writing ball 42.

Here, if the thickness The drawn lines are blurred. On the other hand, if the thickness X is 40% or more of the diameter of the writing ball 42, it becomes difficult to store the oil-based ink 35 in the ball house 55, and writing becomes impossible, so that the ballpoint pen 5 no longer functions. Even if it is possible to write, if the thickness This causes a problem of a decrease in . Therefore, when using a ballpoint pen tip 40 with a writing ball 42 diameter of 0.45 mm or less, in order to suppress the deterioration of the writing feel and increase the drop resistance of the ballpoint pen tip 40, the thickness X should be set to the diameter of the writing ball 42. It is preferable that the content be 23% or more and less than 40%.

Further, in the present embodiment, in a cross section passing through the axis S of the ballpoint pen tip 40, the angle formed by the line segment extending the rear end side of the caulking portion 54 continuous from the tapered portion 51 is the caulking angle K1 (FIG. (see). On the other hand, in a configuration in which the thickness X is smaller than 23% of the diameter of the writing ball 42 (comparative configuration shown in FIG. 6), a caulked portion 54' continuous from the tapered portion 51' in a cross section passing through the axis S of the ballpoint pen tip 40'. The angle formed by the line segment extending the rear end side is the caulking angle K2. Note that in FIG. 6, the same components as in FIG. 5 are denoted by the same reference numerals as in FIG.

The caulking angle K1 is larger than the caulking angle K2. As a result, in this embodiment, the caulking outer diameter G1 (see FIG. 5), which is the outer diameter at the tip end surface of the caulking portion 54, is approximately the same as the caulking outer diameter G2 (see FIG. 6) of the comparative configuration shown in FIG. It consists of

At this time, in this embodiment, the caulking outer diameter G1 is less than 112% of the writing ball 42 diameter. As mentioned above, the diameter of the writing ball 42 is 0.38 mm, but in this embodiment, the caulking outer diameter G1 is 0.401 mm. That is, in this embodiment, the caulking outer diameter G1 is 105% of the writing ball 42 diameter. Here, if the caulking outer diameter G1 is 112% or more of the diameter of the writing ball 42, it is assumed that the caulking portion 54 will easily get caught on the writing surface during writing, resulting in a problem of decreased writing feel. Therefore, when using a ballpoint pen tip 40 with a writing ball 42 diameter of 0.45 mm or less, in order to suppress the deterioration in writing feel and increase the drop resistance of the ballpoint pen tip 40, it is necessary to set the caulking outer diameter G1 to the writing ball 42. Preferably, it is less than 112% of the diameter. Although the lower limit of the above ratio is not particularly limited, it is desirable to set it to 103% or more, for example, since it is necessary to caulk the writing ball 42.

Further, the ballpoint pen tip 40 using a writing ball 42 with a diameter of 0.38 mm as in this embodiment may be replaced with the ballpoint pen tip 40' using a writing ball 42' with a diameter of 0.5 mm, 0.7 mm, or 1.0 mm. When formed with the same taper angle T, the ballpoint pen tip 40 from the tip of the writing ball 42 housed in the ball house 55 to the rear end of the tapered part 51 is smaller than when these writing balls 42' are used. The length along the axis S becomes long.

Here, the diameter of the writing ball 42 in FIG. 7(A) is 0.38 mm, the diameter of the writing ball 42' in FIG. 7(B) is 0.5 mm, and the diameter of the writing ball 42' in FIG. 7(C) is The diameter of the writing ball 42' in FIG. 7(D) is 1.0 mm. Note that in FIGS. 7(B) to (D), for structures similar to those in FIG. 7(A), "'" is added to the same symbols as in FIG. 7(A). As shown in FIG. 7, when the taper angle T is 35° and the ballpoint pen tip 40 is formed using writing balls 42 of different diameters, the smaller the diameter, the easier it is to hold the writing balls 42. , the above length is longer (Y1>Y2>Y3>Y4).

When a ballpoint pen tip 40 with a writing ball 42 diameter of 0.45 mm or less is used, the above length becomes longer than when a ballpoint pen tip 40 with a writing ball 42 diameter larger than 0.45 mm is used. This causes a problem in that the radial thickness X (see FIG. 5) from the outermost edge 62 to the tapered portion 51 becomes thinner, and the drop resistance of the ballpoint pen tip 40 becomes lower.

Therefore, in the ballpoint pen tip 40 of the present embodiment shown in FIG. The length Y1 along the axis S of the ballpoint pen tip 40 from the tip of the writing ball 42 to the rear end of the tapered portion 51 in the state is less than 4 mm. Specifically, in this embodiment, the length Y1 is set to 3.25 mm.

Here, if the above length Y1 is 4 mm or more, the thickness X will become thin in order to keep the taper angle T within the above range, and it will be difficult to set the thickness X to 23% or more of the diameter of the writing ball 42. becomes. Therefore, when using a ballpoint pen tip 40 with a diameter of the writing ball 42 of 0.35 to 0.45 mm, in order to suppress the deterioration of the writing feel and increase the drop resistance of the ballpoint pen tip 40, the length Y1 must be adjusted. It is suitable that it is less than 4 mm. Note that the lower limit of the length Y1 is not particularly limited as long as it is a length that allows the ballpoint pen tip 40 to be formed.

Further, if the taper angle T is less than 30°, the thickness X becomes thin, and it becomes difficult to make the thickness X 23% or more of the diameter of the writing ball 42. On the other hand, if the taper angle T is 50° or more, the outer diameter of the barrel 52 that is continuous with the rear end of the tapered portion 51 (the outer diameter D of the barrel) becomes larger than necessary, and the ballpoint pen tip 40 becomes thicker than necessary. This problem occurs. As a result, the outer diameter of the ballpoint pen 5 also becomes larger than necessary, making it difficult for the user to grip it. Therefore, in order to solve the above problems, it is preferable that the taper angle T is 30° or more and less than 50°.

Further, as described above, in this embodiment, the trunk outer diameter D is set to be 2.35 mm or more and less than 2.6 mm, and specifically, 2.5 mm.

Here, if the body outer diameter D is smaller than 2.35 mm, the thickness X will be thinner in order to keep the taper angle T within the above range, so the thickness X should be 23% or more of the diameter of the writing ball 42. becomes difficult. On the other hand, if the barrel outer diameter D is 2.6 mm or more, there will be a problem that the ballpoint pen tip 40 will become thicker than necessary, similar to the case where the taper angle T is 50 degrees or more. In other words, if the barrel outer diameter D is 2.6 mm or more, the outer diameter of the ballpoint pen 5 will be larger than necessary, making it difficult for the user to grip it, as in the case where the taper angle T is 50 degrees or more. I end up. Therefore, in order to solve the above problems, it is preferable that the trunk outer diameter D be 2.35 mm or more and less than 2.6 mm.

As an example and a comparative example, a ballpoint pen as shown in the above embodiment was manufactured, and the following experiment was conducted. In all Examples and Comparative Examples, the diameter of the writing ball attached to the ballpoint pen tip was 0.38 mm, and the weight of the ballpoint pen was 40 g.

Five samples of the ballpoint pen refills of Examples and Comparative Examples shown in Table 1 below were manufactured. Then, an experiment was conducted to measure the drop resistance of the ballpoint pen refills using ballpoint pens in which the ballpoint pen refills were housed in barrels. Specifically, a ballpoint pen was vertically dropped onto a concrete board from a height of 1 m with the tip facing downward, and 24 hours after the vertical drop onto the concrete board, writing was performed using the ballpoint pen. .

As for the evaluation of the density difference of drawn lines in this experiment, those with good line drawing conditions regardless of the writing direction were given an "A" rating, those in which there was a difference in the drawn line density depending on the writing direction were given a "B" rating, A "C" rating is given to pens with blurring or line skipping, and a "D" rating is given to pens with more blurring or line skipping than a "C" rating. The item was rated "E".

In addition, as for the evaluation of ink leakage in this experiment, cases in which no ink leakage occurred were evaluated as "A," cases in which ink leakage occurred were evaluated as "B," and a larger amount of ink leaked than in the "B" evaluation. Those that leaked a larger amount of ink than the "C" rating were given a "D" rating, and those that did not function as a ballpoint pen and were unable to write were given an "E" rating.

In addition, five other samples were made and an experiment was conducted to see if the lines were blurred due to long-distance writing. Using a writing tester compliant with JIS S6039, writing was performed at a writing angle of 55°, a writing speed of 1 m/min, and a writing load of 4.9 N, and the condition of the drawn line was checked after writing for 1,500 m, and no blurring was observed. Those with slight blurring were given an "A" rating, those with slight blurring were given a "B" rating, and those with clearly visible blurring were given a "C" rating.
The above experimental results are shown in Table 1 below.

From the results in Table 1 above, all samples with a thickness X of 23% or more and less than 39.5 % of the diameter of the writing ball received "A" in the evaluation of the density difference of drawn lines, ink leakage, and long-distance writing. ” was rated. These "A" rated ballpoint pens were able to write over 1500 meters without affecting the handwriting.
On the other hand, as the thickness X became smaller than 23% of the diameter of the writing ball, fewer samples received high evaluations in the evaluation of the density difference between drawn lines and the evaluation of ink leakage. Further, when the thickness X was 39.5 % or more of the diameter of the writing ball, it did not function as a ballpoint pen in the first place, and writing was impossible.

5 Ballpoint pen 10 Barrel 11 Front barrel 12 Rear barrel 13 Clip 14 Tip opening 15 Cap member 16 Decorative member 17 Vertical groove 20 Ballpoint pen refill 30 Ink storage tube 31 Storage portion 32 Extension portion 33 Tail plug 34 Ink follower 35 Oil-based ink 40 Ballpoint pen tip 42 Writing ball 44 Pressing spring 46 Pressing rod 50 Holder 51 Tapered part 52 Body part 53 Insertion part 54 Caulking part 55 Ball house 56 Back hole 57 Ink hole 58 Protruding part 59 Ball house bottom 60 Ball catch 61 Channel groove 62 Bottom outer edge

Claims (5)

A writing ball with a diameter of 0.45 mm or less,
A holder for holding the writing ball, the holder having a cylindrical body and a tapered portion tapered at the tip end of the body;
a ball house formed from the tip of the tapered part toward the rear end of the tapered part and housing the writing ball;
a ball catch that is a bottom surface of the ball house and has a curved surface of the writing ball transferred thereto;
a back hole that is an internal space that is formed from the rear end of the holder toward the front end of the holder and reaches near the ball house;
an ink hole that is an internal space formed to communicate between the ball house and the back hole;
channel grooves, which are a plurality of grooves equally distributed around the ink hole and formed to communicate the ink hole and the ball house;
a caulking portion in which a tip portion of the tapered portion is caulked inward;
a pressing spring that presses the writing ball toward the tip side;
a ballpoint pen tip comprising;
an ink storage tube that stores oil-based ink and to which the ballpoint pen tip is attached;
including;
The caulking outer diameter, which is the outer diameter at the tip surface of the caulking part, is less than 112% of the writing ball diameter,
The radial thickness of the holder from the outermost edge of the bottom surface of the ball house to the tapered portion is 23% or more and 36.8% or less of the writing ball diameter, and the tip side of the pressing spring The load applied to the ballpoint pen refill is 0.01N to 0.09N. The ink storage tube is made of metal and has an inner surface that comes into contact with the oil-based ink and has an arithmetic mean roughness of Ra of 0.5 μm or more according to JIS B0601. 2. The ballpoint pen refill according to claim 1 , wherein the silicone oil is solidified as a deposit by a baking process . The ink storage tube includes a substantially cylindrical, large-diameter storage section that stores the oil-based ink, and a small-diameter extension section that extends from the tip of the storage section, thereby enabling writing over a distance of at least 1500 m. and
The ballpoint pen refill according to claim 1 or 2 , wherein a tail plug is attached to an opening at a rear end of the accommodating portion . The oil-based ink has an ink viscosity of 10 to 3000 mPa s at a shear rate of 38.3 s ^-1 , and the main solvent is other than water,
An ink follower made of a grease-like substance is filled on the rear end side of the oil-based ink,
The ink follower has a viscosity of 1000 to 40,000 mPa·s at 25° C., and a shear thinning index of 0.95 or more at a shear rate of 1 to 10 s ⁻¹ . The ballpoint pen refill according to item 1. The total weight including the barrel is 30 g or more, and a spherical decorative member for making a ballpoint pen refill appear and retract at the rear end of the barrel,
A ballpoint pen in which the ballpoint pen refill according to any one of claims 1 to 4 is accommodated in the barrel , wherein a vertical groove along the axial direction is formed on the surface of the decorative member .