Pen tip for direct-liquid brush pen and direct-liquid brush pen using same

Abstract

[Problem] The problem addressed by the present invention is to provide: a pen tip for a direct-liquid brush pen that has a suitable hardness, can produce a writing feel equivalent to that of general pen tips for direct-liquid brush pens, and can withstand repeated knocking operations when used in a direct-liquid brush pen of a type in which a valve mechanism is activated by a knocking operation to cause ink to exude to the pen tip; and a direct-liquid brush pen using the pen tip. [Solution] Provided is a pen tip for use in a direct-liquid brush pen provided with a valve mechanism, wherein the pen tip is formed by: bundling fibers comprising a nylon resin to produce a fiber bundle; hardening the bundle through adhesion using a synthetic resin binder to produce a rod-like body; and cutting the rod-like body to a desired shape. Preferably, the fibers have a thickness in the range 0.5–5 denier and a porosity, calculated using the following formula, of 70–80%: Porosity = (1 − weight / circular constant × radius2 × length × specific gravity).

Description

Pen tip for direct ink type brush pen and direct ink type brush pen using the same

[0001] The present invention relates to a nib for a direct ink type brush pen and a direct ink type brush pen using the same, and more specifically to a nib for a direct ink type brush pen that is suitable for use in a type of direct ink type brush pen in which a valve mechanism is operated by knocking the nib, causing ink to seep into the nib, and a direct ink type brush pen using the same.

[0002] There have been various types of direct ink pens in the past, but because direct ink pens have the risk of excessive ink seeping out onto the pen tip, causing the so-called ink dripping phenomenon, valve-type pens are becoming more common, in which ink seeps into the pen tip via a valve mechanism that opens when the pen tip is pressed down.

[0003] In the case of a direct ink pen equipped with a general valve mechanism, the nib is hard, so knocking the nib opens the valve and allows ink to seep out of the nib, but in the case of a direct ink brush pen, the nib is soft and shaped like a brush, so knocking the nib does not open the valve. Therefore, in the case of a direct ink brush pen equipped with a conventional valve mechanism, the valve is opened by knocking the ink cartridge (see, for example, Japanese Patent Laid-Open Nos. 2001-150866, 2001-341487, and Japanese Patent No. 6423555) or by pushing in the cap (see, for example, Japanese Patent No. 7008343).

[0004] Japanese Patent Application Laid-Open No. 2001-150866 Japanese Patent Application Laid-Open No. 2001-341487 Japanese Patent No. 6423555 Japanese Patent No. 7008343

[0005] In the case of conventional direct ink brush pens equipped with a valve mechanism, the pen tip is soft and shaped like a brush, and it is thought that the valve cannot be opened by knocking the pen tip. To open the valve, therefore, methods such as knocking the ink cartridge or pushing in the cap are used, but these methods tend to make the mechanism complicated and expensive.

[0006] Therefore, the present invention aims to provide a nib for a direct ink brush pen that has an appropriate hardness, provides a writing feel equivalent to that of a typical direct ink brush pen nib, and can withstand repeated knocking operations when used in a direct ink brush pen that operates a valve mechanism by knocking to allow ink to seep into the nib; and also to provide a direct ink brush pen that can be manufactured at low cost with a simple configuration, and that can open a valve by knocking the nib, allowing ink to seep into the nib, just like a direct ink pen with a typical valve mechanism.

[0007] The invention described in claim 1, which solves the above problem, is a nib for a direct ink brush pen equipped with a valve mechanism, characterized in that fibers made of nylon resin are bundled together to form a fiber bundle, which is then bonded and solidified with a synthetic resin binder to form a rod-shaped body, and then cut into the desired shape.

[0008] In one embodiment, the thickness of the fiber is in the range of 0.5 to 5 denier, and in another embodiment, the porosity calculated by the following formula is 70 to 80%: Porosity = (1 - weight / pi x radius) ２ × length × specific gravity)

[0009] In one embodiment, the synthetic resin binder is a polyurethane resin. Also, in one embodiment, the durometer hardness of the pen tip is 55 to 65.

[0010] The invention described in claim 6, which solves the above problem, is a direct ink brush pen comprising a pen tip described in any one of claims 1 to 5, a cap, and a main body shaft that stores ink and has a lead holder attached to the tip, wherein a valve case with a built-in valve mechanism is fitted into the lead holder, the valve mechanism having a valve core that supports the rear end of the pen tip, and the valve core sliding within the valve case in response to a knocking operation on the pen tip to open and close the ink passage.

[0011] In one embodiment, a resin drip prevention ring is fitted to the pen tip.

[0012] The nib for a direct ink brush pen according to the present invention has a moderate hardness, providing a writing feel equivalent to that of a typical direct ink brush pen nib, and has the effect of being able to withstand repeated knocking operations when used in a direct ink brush pen that operates a valve mechanism by knocking to allow ink to seep into the nib. Furthermore, a direct ink brush pen equipped with a valve mechanism according to the present invention can be manufactured at low cost with a simple configuration, and has the effect of being able to open the valve by knocking the nib, allowing ink to seep into the nib, just like a direct ink pen equipped with a typical valve mechanism.

[0013] Fig. 1 is a vertical cross-sectional view of one embodiment of a direct ink type brush pen according to the present invention with the cap removed. Fig. 2 is a photograph showing the results of a nib durability test of the nib for a direct ink type brush pen according to the present invention. Fig. 3 is a photograph showing the results of a stability test over time of the nib for a direct ink type brush pen according to the present invention. Fig. 4 is a photograph showing the results of a writing-through test of the nib for a direct ink type brush pen according to the present invention.

[0014] The following description of an embodiment of the present invention will be given with reference to the accompanying drawings. Generally, pen nibs are manufactured by bundling thermoplastic resin fibers into a fiber bundle, bonding and solidifying the bundle with a synthetic resin binder, forming a rod-shaped body, and then cutting the body into the desired shape. The thermoplastic resin used in this case can be polyester resin, acrylic resin, polypropylene resin, or the like, but polyester resin is often used. The synthetic resin binder can be phenolic resin, polyurethane resin, melamine resin, epoxy resin, elastomer resin, or the like.

[0015] In contrast, the nib for a direct ink brush pen according to the present invention is a nib for use in a direct ink brush pen equipped with a valve mechanism, and is made by bundling nylon resin as the thermoplastic resin, bonding and solidifying the resin fibers into a fiber bundle with a synthetic resin binder to form a rod-shaped body, which is then cut into the desired shape, and the nylon core uses polyurethane resin as the synthetic resin binder. Nylon fibers are characterized by a low Young's modulus and flexibility. Urethane resin has good adhesion to the nylon fibers, further increasing their elasticity, resilience, and abrasion resistance, allowing the nib to fully exhibit its functions as a direct ink brush pen nib (stopping, strokes, flicks, etc.).

[0016] The denier (thickness) of the nylon resin fiber that constitutes the pen tip of the present invention is in the range of 0.5 to 5 denier, and preferably 1 denier. A range of 0.5 to 10 denier results in a smooth writing feel and proper ink flow. If the thickness exceeds 5 denier, the capillary force is too weak, causing ink dripping and a rough writing feel. If the thickness is 0.5 denier or less, the capillary force is too strong, resulting in poor ink ejection and difficulty in ejecting large particles, as well as high costs.

[0017] The nib hardness (JIS K6253 Type A durometer hardness) of the nylon lead of the present invention is within the range of 55 to 65. The nib hardness is determined by the type of fiber, the number of fibers, the fiber thickness, the adhesive resin, the resin concentration, etc. Incidentally, the nib hardness of a polyester lead is 70 to 75.

[0018] The porosity of the nylon core according to the present invention, calculated by the following formula, is preferably in the range of 70 to 80%, more preferably in the range of 75 to 79%. If the porosity is 70% or less, the ink flow is poor and the writing feel becomes hard, while if it is 80% or more, the ink flow is too good, causing dripping and poor stability over time, and when the writing is pointing upward, the color tends to fade, while when the writing is pointing downward, the pigment clogs and causes blurring. Porosity = (1 - weight / pi x radius) ２ × length × specific gravity) (PO (%) = (1-Wt / πr ２ × l × ρ) The porosity calculated by this formula is mainly affected by the resin concentration, number of fibers, and fiber thickness.

[0019] In manufacturing the nylon core according to the present invention, nylon resin, a fibrous thermoplastic resin, is compressed into a densified fiber bundle by passing it through a molding die heated to 210 to 240° C. The bundle is then impregnated with polyurethane resin, which acts as a synthetic resin binder and has good adhesion to nylon fibers, and dried and solidified to form a rod-shaped body, which is then machined into the desired shape to form a nib for a direct-ink brush pen.

[0020] 1 is a longitudinal cross-sectional view of one embodiment of a direct ink brush pen using a direct ink brush pen nib according to the present invention, with the cap 11 removed. As shown, this direct ink brush pen comprises a main body 1 that directly stores ink 2, a lead holder 4 that is attached to the opening of the main body 1 by screwing or the like, a nib 5 that is a nylon lead supported by the lead holder 4, and a valve mechanism 7 housed in a valve case 6 that fits into the lead holder 4. A stirring ball 3 for stirring the ink 2 together with the ink f2 is housed within the main body 1. A drip prevention ring 8 made of urethane resin or the like is fitted onto the nib 5, and the drip prevention ring 8 is tightly fitted into the lead holder 4 to prevent ink from dripping, which could leak into the lead holder 4.

[0021] The valve mechanism 7 may have a configuration commonly used in knock-type writing instruments. For example, the valve mechanism 7 is housed in a valve case 6 that fits into the lead holder 4, and the rear end of the nib 5 is inserted into the valve wick. When the nib 5 is knocked, the valve wick is pushed in and slides within the valve case 6, and its tapered valve seat flange moves away from the valve seat, opening the ink passage. With the ink passage open, ink 2 inside the main body 1 is supplied to the nib 5. When the knocking operation on the nib 5 is completed, the pushed-in valve wick returns to a position where it closes the ink passage due to the action of a return spring.

[0022] The direct ink brush pen according to the present invention has the above-described structure, and like a general brush pen, it is used for writing by removing the cap 11. The ink 2 is dispensed to the pen tip 5 by directly knocking the pen tip 5.

[0023] The nib 5 manufactured as described above has sufficient durability against repeated knocking, and to demonstrate this, comparative tests were conducted on the nib durability test, stability over time test, and writing completion test between the nib 5 (Example) which is a nylon core according to the present invention, a nib (Comparative Example 1) which is different from the Example in that it has a nylon core but a denier of 6 denier, and a general polyester core (Comparative Example 2). The results are as follows.

[0024] Comparative Example 1 differs from the Examples in that the denier is 6 denier, but the thicker denier weakens the capillary force, making the ink in the nib more likely to separate after long-term storage. This can be seen from the clear smudges that appear when writing with nylon lead 2 facing upward after one month, as shown in Figure 3.

[0025] The pen tip durability test involved observing the initial state before knocking and the state after 100 knocks for the Example and Comparative Examples 1 and 2, and observing the written lines after 100 knocks. As shown in Figure 2, the Example showed no change in shape even after 100 knocks, while Comparative Example 2 showed significant deformation and was no longer suitable for writing. Furthermore, comparing the written lines, the Example showed that the thickness of the written lines could be controlled even after 100 knocks (fine characters could be written by writing vertically, and medium characters could be written by writing at a 65-degree angle, allowing for writing of uniform thickness), while Comparative Example 2 showed difficulty in writing fine characters, difficulty in varying the strength of characters, and inability to write uniform lines. Although not shown in Figure 2, the pen tip durability of Comparative Example 1 was not significantly different from that of the Example.

[0026] In the stability test over time, the pens held facing up and facing down were stored at 50°C for one month, and the writing performance after one month was compared with the writing performance before the test. Figure 3 is a photograph showing the comparison results, and no abnormalities were observed in the writing performance of the Examples. In contrast, in Comparative Example 1, no abnormalities were observed when the pen was held facing down, but as mentioned above, clear smearing was observed when the pen was held facing up. In Comparative Example 2, clear smearing was observed both when the pen was held facing up and when facing down. This difference in Comparative Example 2 is thought to be due to the fact that, as in Comparative Example 1, the capillary force was weak due to the large denier, which resulted in ink separation within the pen tip.

[0027] The writing test was conducted to check whether the ink could be used up without clogging and without any change in writing width or writing performance from the start to the end of writing (97% ink consumption rate after writing about 250 m). As shown in Figure 4, it was confirmed that the ink could be used up until the end of writing without any change in writing width or writing performance.

[0028] As described above, in the case of the nib for a direct-ink brush pen (Example) according to the present invention, good results were obtained in the nib durability test, stability over time test, and writing-through test. This is thought to be due to the compatibility between the nylon resin and polyurethane resin, and the synergistic effect of the denier number (0.5 to 5 denier) of the nylon resin, the nib hardness (55 to 65), and the porosity (70 to 80%).

[0029] The nib for a direct ink brush pen according to the present invention has a moderate hardness, providing a writing feel equivalent to that of a general brush pen nib, and when used in a direct ink brush pen of the type that operates a valve mechanism by knocking to allow ink to seep into the nib, it has the effect of being able to withstand repeated knocking operations.Furthermore, a direct ink brush pen equipped with the valve mechanism according to the present invention can be manufactured at low cost with a simple configuration, and has the effect of opening the valve by knocking the nib and allowing ink to seep into the nib, just like a direct ink pen equipped with a general valve mechanism, so it has great industrial applicability.

Claims

1. A nib for a direct ink brush pen equipped with a valve mechanism, characterized in that the nib is made by bundling nylon resin fibers into a fiber bundle, bonding and solidifying the bundle with a synthetic resin binder to form a rod-shaped body, and then cutting it into the desired shape.

2. The nib for a direct ink type brush pen according to claim 1, wherein the thickness of the fibers is in the range of 0.5 to 5 denier.

3. The nib for a direct ink type brush pen according to claim 1, wherein the porosity calculated by the following formula is 70 to 80%: Porosity = (1 - weight / pi x radius) ２ × length × specific gravity) 4. The nib for a direct ink type brush pen according to claim 1, wherein the synthetic resin binder is a polyurethane resin.

5. The nib for a direct ink type brush pen according to claim 1, wherein the durometer hardness of the nib is 55 to 65.

6. A direct ink brush pen comprising a pen tip as claimed in any one of claims 1 to 5, a cap, and a main body shaft for storing ink and having a lead holder attached to the tip, wherein a valve case incorporating a valve mechanism is fitted into the lead holder, the valve mechanism comprising a valve core that supports the rear end of the pen tip, and the valve core sliding within the valve case in response to a knocking operation on the pen tip to open and close the ink passage.

7. The direct ink brush pen according to claim 6, wherein a resin drip prevention ring is fitted to the pen tip.

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