Writing tip of a writing instrument

Abstract

To provide a pen tip of a writing instrument capable of sufficiently suppressing adhesion of ink to a face portion when the pen tip is immersed in ink and pulled up.SOLUTION: Provided is a pe tip of a writing instrument that is immersed in ink and pulled up, including a metal surface having surface roughness within a predetermined range, which is a water repellency promoting surface having a contact angle of 60 degrees or more with respect to ink.SELECTED DRAWING: Figure 1B

Description

Technical Field

[0001] The present invention relates to the nib of a writing instrument that is immersed in ink and pulled out, including the nibs of fountain pens and dip pens.

Background Art

[0002] Currently, various writing instruments are widespread. For example, in the case of a converter-type fountain pen, when filling the converter with ink, the nib is immersed in the ink and pulled out. Among such nibs, those in which the inner surface of the ink groove and the surrounding surface portion are satin-finished by laser processing or the like have been proposed (see, for example, Patent Document 1). By satin-finishing the inner surface of the ink groove and the surrounding surface portion, the water repellency is suppressed, it becomes easier to get wet, and the ink easily flows to the tip of the nib.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the nib described in Patent Document 1, when immersed in ink and pulled out, the surface portion around the ink groove with enhanced wettability becomes dirty with ink. For this reason, there is a risk that the ink adhering to the peripheral portion of the ink groove may fall and stain the paper surface, or the ink adhering to the peripheral portion of the ink groove may adhere to the user's finger or the like, and the appearance of the nib is also impaired.

[0005] Therefore, an object of the present invention is to solve the above problems and provide a nib of a writing instrument that can sufficiently suppress ink adhesion to the surface when immersed in ink and pulled out.

Means for Solving the Problems

[0006] The pen tip of a writing instrument according to one embodiment of the present invention is a pen tip of a writing instrument that is immersed in ink and then pulled out, a metal surface having a surface roughness within a predetermined range and having a water-repellent promoting surface with a contact angle of 60 degrees or more with respect to the ink.

[0007] The pen tip of a writing instrument according to another embodiment of the present invention is a pen tip of a writing instrument that is immersed in ink and then pulled out, a metal surface having a surface roughness within a predetermined range and having a water-repellent promoting surface with a contact angle 20% or more higher than that of a smooth surface with respect to the ink.

Advantages of the Invention

[0008] As described above, according to the present invention, it is possible to provide a pen tip of a writing instrument that can sufficiently suppress ink adhesion to the surface when immersed in ink and pulled out.

Brief Description of the Drawings

[0009]

Fig. 1A

Fig. 1B

Fig. 2A

Fig. 2B

Fig. 3A

Fig. 3B

Fig. 4A

Fig. 4B

DETAILED DESCRIPTION OF THE INVENTION

[0010] The pen tip of a writing instrument such as a fountain pen or a felt-tip pen may be immersed in ink and pulled up. At that time, however, there is a risk that ink will adhere to the surface of the pen tip. For this reason, there is a risk that the ink adhering to the surface will fall off and stain the paper surface, or that the ink adhering to the surface will adhere to the user's finger or the like, and the appearance of the pen tip will also be impaired. To solve such problems, as described below, the inventors conducted a test to measure the contact angle of the pen tip with respect to ink.

[0011] (Measurement of Contact Angle) Stainless steel is often used as the material for the pen tip of a fountain pen or a felt-tip pen. The inventors conducted a test to measure the contact angle using a stainless steel plate. Specifically, stainless steel plates having various surface roughnesses were prototyped, and ink used for a fountain pen was dropped thereon to measure the contact angle. More specifically, it was measured by the liquid drop method (θ / 2 method) using an automatic contact angle meter DMo-602 manufactured by Kyowa Interface Science Co., Ltd. Light was applied to the liquid drop dropped on the stainless steel plate, an image of the liquid drop was captured by an imaging device, and the contact angle was calculated by image analysis. Using the above automatic contact angle meter, 1 μL of ink was dropped on stainless steel plates with different surface roughnesses, the liquid drop was projected with light, and images of the liquid drop were captured at 5 s and 10 s after droplet landing, and the contact angle was calculated by image analysis.

[0012] Next, with reference to FIGS. 1A and 1B, the results of the test for measuring the contact angle will be described in detail. FIG. 1A is a table showing the results of a test in which stainless steel plates having various surface roughnesses were prototyped, and ink used for a fountain pen or the like was dropped thereon to measure the contact angle. FIG. 1B is a graph representing the test results shown in FIG. 1A. The ink used in this test has a surface tension of 49.4 mN / m as measured by the vertical plate method using a platinum plate at 20°C. Although it is generally said that the surface tension of inks used in fountain pens and felt-tip pens is within the range of 40 to 60 mN / m, it can be said that the ink used in the test has a typical surface tension for inks used in fountain pens and felt-tip pens.

[0013] In the table of Fig. 1A, the contact angles after 5 seconds and 10 seconds corresponding to the surface roughness of the stainless steel plate are shown. In the graph of Fig. 1B, the horizontal axis represents the surface roughness (Sa [μm]) of the stainless steel plate, and the vertical axis represents the contact angle (degrees). In Fig. 1B, the data shown in Fig. 1A are plotted and connected with a smooth curve to draw a graph. As is clear from Fig. 1A and Fig. 1B, the contact angle after 10 seconds is smaller than the contact angle after 5 seconds. From a practical point of view of how much the pen tip ejects ink, in the following, the discussion will be based on the data after 10 seconds with a smaller value.

[0014] In the table of Fig. 1A, the surface with an arithmetic mean height Sa (ISO25718) of 0.082 μm at the top shows the surface roughness of a smooth surface without polishing. The next surface with an arithmetic mean height Sa (ISO25718) of 0.090 μm shows the surface roughness of a surface polished using P400 (so-called 400-grit) abrasive paper according to JIS R6010. As we move down the table, it shows the surface roughness polished using coarser abrasive paper. For example, the surface with an arithmetic mean height Sa (ISO25718) of 0.330 μm shows the surface roughness of a surface polished using P60 (so-called 60-grit) abrasive paper according to JIS R6010.

[0015] Regarding the contact angle, as is clear from Fig. 1B, as the surface roughness increases from the smooth surface side, the contact angle increases. The contact angle reaches a peak at an arithmetic mean height Sa (ISO25718) of about 0.200 μm, and when the surface roughness is further increased, the contact angle shows a tendency to change from an increase to a decrease.

[0016] For example, on a smooth surface with an arithmetic mean height Sa (ISO25718) of 0.082 μm, the contact angle is less than 50 degrees. On surfaces with surface roughnesses of 0.090 μm and 0.330 μm in terms of arithmetic mean height Sa (ISO25718), they have contact angles exceeding 60 degrees. On surfaces with surface roughnesses of 0.276 μm and 0.319 μm in terms of arithmetic mean height Sa (ISO25718), they have contact angles exceeding 70 degrees. On a surface with a surface roughness of 0.159 μm in terms of arithmetic mean height Sa (ISO25718), it has a contact angle exceeding 80 degrees. On a surface with a surface roughness of 0.360 μm in terms of arithmetic mean height Sa (ISO25718), the contact angle is less than 60 degrees. Thus, it was found that when the stainless steel plate has a surface roughness within a predetermined range, a larger contact angle can be obtained compared to a smooth surface.

[0017] Prototype fountain pen tips made of stainless steel with various surface roughnesses as described above were prepared, and a test was conducted to actually observe the state after dipping in ink and pulling it out. As a result, it was found that for fountain pen tips with a smooth surface where the contact angle is less than 50 degrees, ink adhesion becomes a problem. On the other hand, it was found that for fountain pen tips with a surface where the contact angle is 60 degrees or more, ink adhesion can be sufficiently suppressed.

[0018] (Examples and Comparative Examples) Next, with reference to FIGS. 2A and 2B, the state of being dipped in ink and pulled out will be described for an example of a fountain pen tip having a surface with a contact angle of 60 degrees or more and a comparative example of a fountain pen tip having a smooth surface. FIG. 2A is a diagram (photograph) showing the examples and the comparative example. FIG. 2B is a diagram (photograph) showing the state after the examples and the comparative example shown in FIG. 2A are dipped in ink and pulled out.

[0019] The left side of FIGS. 2A and 2B shows a fountain pen tip (comparative example) having a smooth surface with a contact angle of less than 50 degrees, and the right side shows a fountain pen tip (example) having a surface roughness with a contact angle of 60 degrees or more. As shown in FIG. 2B, when the fountain pen tip was dipped in ink and pulled out, in the comparative example, ink adhered to the entire surface of the face part. On the one hand, when the pen tip was dipped into the ink and then pulled out, in the examples, it was demonstrated that the surface of the pen tip generally repelled the ink and sufficiently suppressed ink adhesion. Furthermore, it was demonstrated that with a pen tip having a surface roughness with a contact angle of 70 degrees or more, the surface repelled the ink more strongly and could more effectively suppress ink adhesion.

[0020] (Range of contact angle) As described above, on a surface with a contact angle of 60 degrees or more, ink adhesion can be sufficiently suppressed in practical use. Such a surface can be referred to as a "water repellency promoting surface". Furthermore, on a water repellency promoting surface with a contact angle of 70 degrees or more, ink adhesion can be more effectively suppressed.

[0021] Considering suppressing ink adhesion by increasing the surface roughness compared to a smooth surface, it is also conceivable to define the above range by comparison with a reference smooth surface rather than by the value of the contact angle. Since the contact angle of the smooth surface can be regarded as approximately 50 degrees, a water repellency promoting surface with a contact angle of 60 degrees or more can also be expressed as a water repellency promoting surface with a contact angle 20% (=60 / 50 - 1) or more higher than that of the smooth surface. Similarly, a water repellency promoting surface with a contact angle of 70 degrees or more can also be expressed as a water repellency promoting surface with a contact angle 40% (=70 / 50 - 1) or more higher than that of the smooth surface.

[0022] That is, on a water repellency promoting surface with a contact angle 20% or more higher than that of the smooth surface, ink adhesion can be sufficiently suppressed, and on a water repellency promoting surface with a contact angle 40% or more higher than that of the smooth surface, ink adhesion can be more effectively suppressed.

[0023] (Range of surface roughness) Next, while referring to FIG. 1B, the range of the surface roughness of the water repellency promoting surface that satisfies the above contact angle range will be examined. As is clear from FIG. 1B, when the surface roughness is in the range of 0.09 μm or more and 0.35 μm or less in terms of the arithmetic mean height Sa (ISO25718), the contact angle becomes 60 degrees or more. Furthermore, when the surface roughness is in the range of 0.12 μm or more and 0.31 μm or less in terms of the arithmetic mean height Sa (ISO25718), the contact angle becomes 70 degrees or more.

[0024] Similarly, when the surface roughness is in the range of 0.09 μm or more and 0.35 μm or less in terms of the arithmetic mean height Sa (ISO25718), the contact angle becomes 20% or more higher than that of a smooth surface. Further, when the surface roughness is in the range of 0.12 μm or more and 0.31 μm or less in terms of the arithmetic mean height Sa (ISO25718), the contact angle becomes 40% or more higher than that of a smooth surface.

[0025] The graph in Fig. 1B shows the test results using an ink having a representative surface tension (49.4 mN / m). Therefore, when having the above surface roughness range, it is considered that ink adhesion can be sufficiently suppressed in practice for any commercially available ink used in fountain pens and felt-tip pens. In particular, when in the range of 0.12 μm or more and 0.31 μm or less in terms of the arithmetic mean height Sa (ISO25718) corresponding to a contact angle of 70 degrees or more, it is considered that ink adhesion can be surely suppressed for any commercially available ink used in fountain pens and felt-tip pens.

[0026] (Relationship between surface roughness and contact angle) As described above, within the range having a water-repellent promoting surface with a contact angle of 60 degrees or more, when increasing the surface roughness from the smooth side, initially the contact angle increases, and when further increasing the surface roughness, it reaches a peak, and when increasing the surface roughness beyond the peak surface roughness, the contact angle tends to change from an increase to a decrease (see Fig. 1B). This tendency will be described in detail below with reference to Figs. 3A and 3B. Fig. 3A is a diagram schematically showing a state where ink adheres to the surface of the pen tip with minute unevenness formed. Fig. 3B is a diagram schematically showing a state where ink adheres to the surface of the pen tip with unevenness larger than the unevenness shown in Fig. 3A formed.

[0027] Referring to FIGS. 3A and 3B, consider the case where the metal surface is roughened from a smooth surface and the size of the irregularities formed on the surface is gradually increased. When minute irregularities 2 as shown in FIG. 3A are formed, the ink does not flow into the recess 2A of the irregularities 2 due to capillary action. As a result, the ink droplet D and the convex portion 2B of the irregularities 2 are in a state of point contact, and it is considered that the water repellency increases and the contact angle increases.

[0028] When maintaining the state of FIG. 3A, if the size of the irregularities increases, the degree of point contact further increases, so it is considered that the contact angle increases. Furthermore, as the size of the irregularities is increased, as shown in FIG. 3B, the ink flows into the recess 4A of the irregularities 4 due to capillary action and is filled in the recess 4A. For this reason, the contact area between the ink droplet D and the irregularities 4 (the recess 4A and the convex portion 4B) increases. Thereby, the interfacial free energy increases, the wettability increases, and it is considered that the contact angle decreases.

[0029] Patent Document 1 describes that "roughening makes it easier to get wet", and it is assumed that the state shown in FIG. 3B occurs in this roughened surface. Therefore, it is assumed that the roughened surface described in Patent Document 1 is a surface much rougher than the above surface roughness range.

[0030] Thus, within a predetermined range, when increasing the surface roughness from the smooth side, initially the contact angle increases, and when further increasing the surface roughness, the contact angle tends to change from increasing to decreasing. By grasping this tendency, it is possible to obtain the range of the optimal surface roughness that gives a large contact angle. In fact, since the surface roughness of the pen tip has a certain width, it is preferable to set the roughness so that the median value of the surface roughness becomes the peak of the contact angle during surface processing.

[0031] (Pen tip according to the present invention) As described above, the pen tip according to the present invention is a pen tip of a writing instrument that is immersed in ink and then pulled out, and is a metal surface having a surface roughness within a predetermined range, and has a water-repellent promoting surface with a contact angle with respect to the ink of 60 degrees or more. Similarly, the pen tip according to the present invention is a metal surface having a surface roughness within a predetermined range, and has a water-repellent promoting surface with a contact angle with respect to the ink that is 20% or more higher than that of a smooth surface. Note that the water-repellent promoting surface can be either the surface of the base metal or the surface of a plated metal.

[0032] When the pen tip has such a contact angle, when the pen tip is immersed in ink and then pulled out, the ink adhesion on the surface of the pen tip can be sufficiently suppressed. As a result, it is possible to prevent the ink from dripping from the pen tip and soiling the paper surface, or the ink on the pen tip from adhering to the user's finger or the like, and the appearance of the pen tip is not impaired.

[0033] When the water-repellent promoting surface made of the stainless steel surface of the pen tip has a surface roughness within the range of 0.09 μm or more and 0.35 μm or less in terms of the arithmetic mean height Sa (ISO25718), a contact angle of 60 degrees or more, or a contact angle 20% or more higher than that of a smooth surface can be obtained. When the pen tip has such a range of surface roughness, when the pen tip is immersed in ink and then pulled out, the ink adhesion on the surface of the pen tip can be surely suppressed.

[0034] Furthermore, it is more preferable that the contact angle of the water-repellent promoting surface of the pen tip according to the present invention with respect to the ink is 70 degrees or more. Similarly, it is more preferable that the pen tip according to the present invention has a water-repellent promoting surface with a contact angle with respect to the ink that is 40% or more higher than that of a smooth surface.

[0035] When the pen tip has such a contact angle, when the pen tip is immersed in ink and then pulled out, the ink adhesion on the surface of the pen tip can be more effectively suppressed.

[0036] At this time, when the water-repellent promoting surface composed of the surface of the stainless steel at the pen tip has a surface roughness in the range of 0.12 μm or more and 0.33 μm or less in terms of arithmetic mean height Sa (ISO 25718), a contact angle of 70 degrees or more, or a contact angle 40% or more higher than that of a smooth surface can be obtained. When the pen tip has a surface roughness within such a range, when the pen tip is immersed in the ink and pulled out, the ink adhesion on the surface of the pen tip can be surely and more effectively suppressed.

[0037] (Modification example) Next, with reference to FIGS. 4A and 4B, as a modification example, a pen tip formed with an engraving by a surface that is not a water-repellent promoting surface adjacent to the water-repellent promoting surface will be described. FIG. 4A is a perspective view showing a modification example in which an engraving is formed on the pen tip according to the present invention. FIG. 4B is a perspective view showing a state after the pen tip shown in FIG. 4A is immersed in the ink and pulled out.

[0038] As shown in FIG. 4A, an engraving excellent in aesthetic appearance can be formed by a surface that is not a water-repellent promoting surface adjacent to the water-repellent promoting surface. In FIG. 4A, a state where a plurality of S-shaped engravings are formed by a surface that is not a water-repellent promoting surface surrounded by the water-repellent promoting surface is shown. Note that the shape of the engraving shown in FIG. 4A is merely an example, and engravings of any other shape can be formed. Furthermore, as shown in FIG. 4B, when the pen tip is immersed in the ink and pulled out, ink remains on the surface that is not a water-repellent promoting surface, and no ink adheres to the surrounding water-repellent promoting surfaces. For this reason, the pattern of the engraving is more prominently shown by the ink remaining on the surface that is not a water-repellent promoting surface.

[0039] In this way, when an engraving is formed by a surface that is not a water-repellent promoting surface adjacent to the water-repellent promoting surface, the pattern of the engraving can be further emphasized by the ink remaining on the surface that is not a water-repellent promoting surface, and a pen tip with more excellent aesthetic appearance can be provided.

[0040] <Surface having a water-repellent promoting surface> As described above, considering the effect of suppressing ink adhesion to the surface portion of the pen tip and the decorative effect of the pen tip, it is preferable that at least the water-repellent promoting surface is provided on the front (outer) surface of the pen tip. Thereby, it is possible to suppress ink adhesion and provide a pen tip with excellent aesthetics at a low manufacturing cost.

[0041] Although the embodiments, modified examples, etc. of the present invention have been described, the disclosed content may change in the details of the configuration, and changes in the combination or order of elements can be realized without departing from the scope and spirit of the claimed present invention.

Explanation of Reference Numerals

[0042] 2 unevenness 2A recess 2B protrusion 4 unevenness 4A recess 4B protrusion D ink droplet

Claims

1. The pen tip of a writing instrument that is immersed in ink and pulled out, A metal surface having a surface roughness within a predetermined range, having a water-repellent promoting surface with a contact angle of 60 degrees or more with respect to the ink, The water-repellent promoting surface made of a stainless steel surface has a surface roughness in the range of 0.09 μm or more and 0.35 μm or less in arithmetic mean height Sa (ISO 25718). The pen tip of the writing instrument is characterized by this.

2. The pen tip of the writing instrument according to claim 1, wherein the contact angle of the water-repellent promoting surface with respect to the ink is 70 degrees or more.

3. The water-repellent promoting surface made of a stainless steel surface has a surface roughness in the range of 0.12 μm or more and 0.31 μm or less in arithmetic mean height Sa (ISO 25718). The pen tip of the writing instrument according to claim 2 is characterized by this.

4. The pen tip of a writing instrument that is immersed in ink and pulled out, A metal surface having a surface roughness within a predetermined range, having a water-repellent promoting surface with a contact angle 20% or more higher than that of a smooth surface with respect to the ink, The water-repellent promoting surface made of a stainless steel surface has a surface roughness in the range of 0.09 μm or more and 0.35 μm or less in arithmetic mean height Sa (ISO 25718). The pen tip of the writing instrument is characterized by this.

5. The pen tip of the writing instrument according to claim 4, wherein the contact angle of the water-repellent promoting surface with respect to the ink is 40% or more higher than that of a smooth surface.

6. The water-repellent promoting surface made of a stainless steel surface has a surface roughness in the range of 0.12 μm or more and 0.31 μm or less in arithmetic mean height Sa (ISO 25718). The pen tip of the writing instrument according to claim 5 is characterized by this.

7. Within the predetermined range, when the surface roughness is increased from the smooth side, initially the contact angle increases, and when the surface roughness is further increased, the pen tip is made of a material that shows a tendency for the contact angle to change from an increase to a decrease. The pen tip of the writing instrument according to any one of claims 1 to 6 is characterized by this.

8. The pen tip of the writing instrument according to any one of claims 1 to 7, wherein the water-repellent promoting surface is provided on the front (front) surface of the pen tip.

9. The pen tip of the writing instrument according to claim 8, wherein an engraving is formed by the non-water-repellent promoting surface adjacent to the water-repellent promoting surface.

Images