Writing instrument

Abstract

Provided is a writing instrument capable of reliably supplying ink to a nib and improving ink diffusivity. This writing instrument (A) is characterized by being provided with a cotton core (17) having two or more types of pore diameter distributions. According to cross-sectional image analysis, the frequency of less than 90 [mu] m of the core (17) is high, preferably in a region of a radius of 0.5 mm from the center.

Description

Technical Field

[0001] The present specification relates to a writing tool capable of reliably supplying ink to a pen tip and improving ink diffusibility. Background Art

[0002] Conventionally, there are known cotton cores for writing instruments having improved ink diffusibility for the purpose of reliably supplying ink to a pen tip, and writing instruments using the cotton cores for writing instruments.

[0003] For example, there is known a reservoir for a non-homogeneous fiber fluid for writing tools such as oil-based markers and fluorescent markers, the reservoir comprising a rod having a core component comprising fibers and a peripheral component comprising fibers, wherein the core component has a first characteristic, and the peripheral component has a second characteristic different from the first characteristic, in which the first characteristic and the second characteristic are independently selected from the group consisting of fiber volume density, fiber diameter, fiber material, fiber morphology, fiber surface tension, capillary force, fluid absorption capacity, color, and combinations thereof, and in addition, in the above-mentioned reservoir, the fiber volume density is about 0.01 g / cm 3 ~About 0.4g / cm 3 The fiber diameter is in the range of about 0.5 μm to about 50 μm (see, for example, Patent Document 1).

[0004] This reservoir is equivalent to a so-called cotton core for writing tools. By setting the fiber volume density of the cotton core to a "dense cotton core", the ink supplied to the cotton core can be diffused, and the ink can be reliably supplied to the two nibs at the two ends of the pen body to write. The dense cotton core is characterized in that the fibers are densely packed in the radial center of the cotton core and sparsely packed in the circumference. When the dense cotton core is filled with ink, the densely packed part preferentially absorbs the ink, and the ink is quickly supplied to the two end surfaces of the cotton core, thereby improving the ink diffusibility of the cotton core.

[0005] Furthermore, in other documents, for example, the following marking pen is known, characterized in that the marking pen comprises: a pen body; a cotton core, which is accommodated inside the pen body and consists of a dense part and a sparse part, the dense part is located near the axis in a cross section perpendicular to the length direction and has a relatively low porosity, and the sparse part is located around the dense part and has a relatively high porosity; water-based ink, which is impregnated in the cotton core and has a static surface tension value of less than 35 mN / m; and a writing tip, which is connected to the dense part and uses capillary force to guide the water-based ink to the tip (for example, refer to patent document 2 of the present applicant).

[0006] However, although the above-mentioned Patent Documents 1 and 2 are cotton cores for writing instruments that have not been available before and writing instruments using the same, there is a situation in the above-mentioned Patent Document 1 that ink cannot be efficiently supplied to the pen tip, and the current situation is that the above-mentioned Patent Documents 1 and 2 are required to further improve the ink diffusibility.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Publication No. 2022-501226 (claims, Figure 1 wait)

[0010] Patent Document 2: Japanese Patent Application Publication No. 2021-66043 (Claims, Figure 7 wait) Summary of the invention

[0011] Problem that the invention aims to solve

[0012] The present disclosure aims to solve the above-mentioned conventional technical problems and current situations, and its object is to provide a writing tool that can more efficiently supply ink to a pen tip and further improve ink diffusibility.

[0013] Solutions for solving problems

[0014] The inventors of the present invention have conducted intensive studies to solve the above-mentioned conventional problems and the like, and as a result, have found that a writing instrument having the above-mentioned purpose can be obtained by setting a cotton core composed of a fiber bundle to a specific structure, thereby completing the present disclosure.

[0015] That is, the writing instrument of the present disclosure is characterized in that the writing instrument includes a cotton core having two or more pore diameter distributions.

[0016] Preferably, according to the cross-sectional image analysis, in a region having a radius of 0.5 mm from the center, the frequency of the cotton core being smaller than 90 μm is high.

[0017] It is preferable that the ink composition absorbed in the cotton core is an ink composition containing a fine resin pigment containing a dye.

[0018] Effects of the Invention

[0019] According to the present disclosure, a writing instrument is provided that can more efficiently supply ink to a pen tip and can further improve ink diffusibility.

[0020] The objects and effects of the present disclosure are realized and achieved particularly by using the constituent elements and combinations pointed out in the claims.Both the above general description and the following detailed description are exemplary and illustrative and do not limit the present disclosure described in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a diagram showing a writing tool as an example of an embodiment of the present disclosure, Figure 1 (a) is the main view, Figure 1 (b) is a top view. Figure 1 (c) is a longitudinal section view when viewed from the front. Figure 1 (d) is Figure 1 (b) is a longitudinal cross-sectional view of the embodiment of the present invention.

[0022] Figure 2 It means from Figure 1 The writing instrument is shown with the cap removed. Figure 2 (a) is a top view, Figure 2 (b) is the main view, Figure 2 (c) is a bottom view. Figure 2 (d) is Figure 2 (b) is a longitudinal section view of Figure 2 (e) is Figure 2 (c) is a longitudinal cross-sectional view of .

[0023] Figure 3 Yes means Figure 1 A partial enlarged view of the nib side of a writing instrument. Figure 3 (a) is the main view, Figure 3 (b) is a longitudinal sectional view thereof.

[0024] Figure 4 (a) is viewed from the front side Figure 3 A three-dimensional image of the nib of a writing instrument, Figure 4 (b) is a stereoscopic image of the pen tip viewed from the rear side.

[0025] Figure 5 (a) is a front view showing an example of a cotton core for a writing instrument disclosed in the present invention, Figure 5 (b) is Figure 5 The X-ray cross-sectional view of the cotton core (a) is a schematic diagram of a state having two or more pore size distributions.

[0026] Figure 6 1 are diagrams showing an example of a holder having a visible portion for a pen tip of a writing instrument, Figure 6 (a) is a stereoscopic view viewed from the front side, Figure 6 (b) is a top view. Figure 6 (c) is a stereoscopic view viewed from the rear side. Figure 6 (d) is the left view, Figure 6 (e) is the main view, Figure 6 (f) is the right view, Figure 6(g) is a stereoscopic view viewed from above the front side, Figure 6 (h) is a longitudinal section view, Figure 6 (i) is a stereoscopic view viewed from above on the rear side, Figure 6 (j) is a bottom view.

[0027] Figure 7 Is installed in Figure 6 Each figure shows an example of the writing part of the pen tip, Figure 7 (a) is a top view, Figure 7 (b) is a stereogram, Figure 7 (c) is the main view, Figure 7 (d) is the right view.

[0028] Figure 8 (a) and (b) are optical microscope cross-sectional observation and binarized images (resolution of the image is about 1.27 μm / pixel) of the image analysis pattern of Production Example 1 (Sample A).

[0029] Fig. 9 (a) and (b) are optical microscope cross-sectional observation and binarized images (resolution of the image is about 1.28 μm / pixel) of the image analysis pattern of Production Example 2 (Sample B).

[0030] Fig.10 This is the pore distribution diagram of Manufacturing Example 1 (Sample A) (the largest circle inscribed in the pore portion). In the pore distribution diagram, a large number of circular gray (yellow) colors indicate that the pore diameter is greater than 90 μm, white dots (white) are pores, and black dots (red) are fibers. The dark gray (green) color that forms the entire area except for the circular gray, white dots, and black dots indicates that the pore diameter is less than 90 μm. The dark gray (green) and circular gray (yellow) are roughly the same as a whole.

[0031] Fig.11 This is the pore distribution diagram of Manufacturing Example 2 (Sample B) (the largest circle inscribed in the pore portion). In the pore distribution diagram, a large number of circular gray (yellow) indicates that the pore diameter is greater than 90 μm, white dots (white) are pores, and black dots (red) are fibers. The entire area except for the circular gray, white, and black dots is dark gray (green), with more dark gray (green) and less circular gray (yellow) in the center.

[0032] Fig.12This is a graph of the pore size distribution (largest circle distribution of the inscribed pore portion) of Production Examples 1 and 2 (Samples A and B) [horizontal axis: pore diameter (μm), vertical axis: area frequency (moving average: %)]. In the area frequency, the moving average is used for each data point, and the measurement area is Fig.13 The semicircular portion shown in (c).

[0033] Fig.13 (a) to (c) are diagrams showing the relationship between the spatial distribution of pores (distance from the center of the circle and pore area frequency) of Manufacturing Examples 1 and 2 (Samples A and B) and the measurement method. Fig.13 (a) is a graph when the pore diameter is less than 90 μm [horizontal axis: radius from the center (μm), vertical axis: area frequency (moving average)], Fig.13 (b) is a graph when the pore diameter is 90 μm or more [horizontal axis: radius from the center (μm), vertical axis: area frequency (moving average)], Fig.13 (c) is an explanatory diagram illustrating the measurement method of the radius from the center and the area frequency. The measurement is performed at an arbitrary radius from the center (measured on the yellow solid line relative to the radius of the yellow arrow). In the area frequency, a moving average is used for each data point.

[0034] Fig.14 This is a graph showing the pore diameter and area frequency obtained by plotting the pore distribution (distribution of the largest circle inscribed in the pore portion) of Production Examples 1 and 2 (samples A and B) at threshold values ​​of 50 μm, 90 μm, and 100 μm.

[0035] Fig.15 This is a graph of the pore distribution (the largest circle inscribed in the pore portion) with a threshold value of 100 μm for Manufacturing Example 1 (Sample A). In the pore distribution graph, dark gray (green) represents pores with a diameter greater than 0 and less than 100 μm, circular gray (yellow) represents pores with a diameter greater than 100 μm, white dots (white) represent pores, and black dots (red) represent fibers. The dark gray (green) and circular gray (yellow) are roughly the same overall.

[0036] Fig.16 This is a graph of the pore distribution (the largest circle inscribed in the pore portion) with a threshold value of 90 μm for Manufacturing Example 1 (Sample A). In the pore distribution graph, dark gray (green) represents pores with a diameter greater than 0 and less than 90 μm, circular gray (yellow) represents pores with a diameter greater than 90 μm, white dots (white) represent pores, and black dots (red) represent fibers. The dark gray (green) and circular gray (yellow) are roughly the same overall.

[0037] Fig.17This is a graph of the pore distribution (the largest circle inscribed in the pore portion) with a threshold value of 50 μm for Manufacturing Example 1 (Sample A). In the pore distribution graph, dark gray (green) represents pores with a diameter greater than 0 and less than 50 μm, circular gray (yellow) represents pores with a diameter greater than 50 μm, white dots (white) represent pores, and black dots (red) represent fibers. The dark gray (green) and circular gray (yellow) are roughly the same overall.

[0038] Fig.18 This is a graph of the pore distribution (the largest circle inscribed in the pore portion) with a threshold value of 100 μm for Manufacturing Example 2 (Sample B). In the pore distribution graph, dark gray (green) represents pores with a diameter greater than 0 and less than 100 μm, circular gray (yellow) represents pores with a diameter greater than 100 μm, white dots (white) represent pores, and black dots (red) represent fibers. There are more dark gray (green) in the center and fewer circular gray (yellow) in the center.

[0039] Fig.19 This is a graph of the pore distribution (the largest circle inscribed in the pore portion) with a threshold value of 90 μm for Manufacturing Example 2 (Sample B). In the pore distribution graph, dark gray (green) represents pores with a diameter greater than 0 and less than 90 μm, circular gray (yellow) represents pores with a diameter greater than 90 μm, white dots (white) represent pores, and black dots (red) represent fibers. There are more dark gray (green) and fewer circular gray (yellow) dots in the center.

[0040] Fig. 20 This is a graph of the pore distribution (the largest circle inscribed in the pore portion) with a threshold value of 50 μm for Manufacturing Example 2 (Sample B). In the pore distribution graph, dark gray (green) represents pores with a diameter greater than 0 and less than 50 μm, circular gray (yellow) represents pores with a diameter greater than 50 μm, white dots (white) represent pores, and black dots (red) represent fibers. There are more dark gray (green) and fewer circular gray (yellow) dots in the center.

[0041] Fig.21 (a) to (c) are graphs showing the relationship between the distance from the circle center (pore diameter is 0 or more and less than 100 μm, pore diameter is 100 μm or more) and the pore diameter frequency of Manufacturing Examples 1 and 2 (Samples A and B), and graphs showing the measurement method. Fig.21 (a) is a graph when the pore diameter is greater than 0 and less than 100 μm [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig.21 (b) is a graph when the pore diameter is 100 μm or more [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig.21(c) is an explanatory diagram for explaining the method of measuring the radius from the center and the number frequency.

[0042] Fig. 22 (a) to (c) are graphs showing the relationship between the distance from the circle center (pore diameter is greater than 0 and less than 90 μm, pore diameter is greater than 90 μm) and the pore diameter frequency of Manufacturing Examples 1 and 2 (Samples A and B), and graphs showing the measurement method. Fig. 22 (a) is a graph when the pore diameter is greater than 0 and less than 90 μm [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig. 22 (b) is a graph when the pore diameter is 90 μm or more [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig. 22 (c) is an explanatory diagram for explaining the method of measuring the radius from the center and the number frequency.

[0043] Fig.23 (a) to (c) are graphs showing the relationship between the distance from the circle center (pore diameter is greater than 0 and less than 50 μm, pore diameter is greater than 50 μm) and the pore diameter frequency of Manufacturing Examples 1 and 2 (Samples A and B), and graphs showing the measurement method. Fig.23 (a) is a graph when the pore diameter is greater than 0 and less than 50 μm [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig.23 (b) is a graph when the pore diameter is 50 μm or more [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig.23 (c) is an explanatory diagram for explaining the method of measuring the radius from the center and the number frequency.

[0044] Fig.24 (a) to (d) are graphs showing the relationship between the distance from the circle center and the pore diameter frequency in Manufacturing Examples 1 and 2 (Samples A and B). Fig.24 (a) is a graph when the pore diameter of Manufacturing Example 1 (Sample A) is less than the threshold value (50 μm, 90 μm, 100 μm) [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig.24 (b) is a graph of the pore diameter of Production Example 1 (Sample A) when it is greater than or equal to the threshold value (50 μm, 90 μm, 100 μm) [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig.24 (c) is a graph of the pore diameter of Manufacturing Example 2 (Sample B) when it is less than the threshold value (50 μm, 90 μm, 100 μm) [horizontal axis: radius from the center (μm), vertical axis: frequency], Fig.24 (d) is a graph when the pore diameter of Production Example 2 (Sample B) is equal to or larger than the threshold value (50 μm, 90 μm, 100 μm) [horizontal axis: radius from the center (μm), vertical axis: frequency]. DETAILED DESCRIPTION

[0045] Below, while referring to the attached Figure 1 The embodiments of the present disclosure are described in detail. However, the protection scope of the present disclosure is not limited to the embodiments described in detail below, and it should be noted that it involves the inventions described in the patent claims and their equivalents.

[0046] In addition, in each figure, the "front" of the writing tool A and its components refers to the direction of the top end of the writing tool A, the "rear" refers to the direction of the opposite side, the "axial direction" refers to the direction of the axis running from the front to the rear of the writing tool body (pen barrel), and the "transverse direction" refers to the direction orthogonal to the axial direction. In addition, the reference numerals commonly marked between the figures indicate the same structure or component even if not specifically mentioned in the description of each figure.

[0047] (First embodiment: overall structure)

[0048] Figure 1 to Figure 7 The drawings illustrate a marker pen type writing instrument A according to the first embodiment of the present disclosure, a cotton core 17 having two or more pore diameter distributions, a pen tip 20, an example of a writing part 25, and the like, which are components used for the writing instrument.

[0049] like Figure 1 As shown in (a) to (d) of the present embodiment, the writing tool A of this embodiment is a dual-type writing tool having a pen tip 20 that guides ink supplied from the writing tool body (pen barrel) 10 and has a visible portion that can visually confirm the writing direction, and a rod-shaped polyacetal pen tip 40 is also provided on the opposite side of the pen tip 20. In addition, a pen cap 50 that protects the pen tip 20 and a pen cap 60 that protects the pen tip 40 are detachably mounted on both sides of the writing tool body 10. The pen cap 50 has a pen clip 51, a friction body 53, and a vent 54.

[0050] (Writing tool body 10, rear pen holder 11)

[0051] like Figure 1 to Figure 4 As shown, the writing instrument body 10 of this embodiment is composed of a rear pen body 11 and a front pen body 16. The rear pen body 11 is composed of a cylindrical body and contains a cotton core 17 impregnated with writing instrument ink, and a holding portion 13 with a reduced diameter at one end side on the right side in the figure, and the holding portion 13 has a fitting portion 12 for fixing and holding a holding piece 45 of a thin-letter rod-shaped pen tip 40 by fitting, and a pen cap 60 is detachably mounted on the large-diameter outer peripheral portion 13a of the holding portion 13.

[0052] In addition, the opening portion at the other end of the left side of the rear pen barrel 11 is fixed by fitting or the like, and the front pen barrel 16 is fixed with the pen tip 20 having a visible portion that can visually confirm the writing direction. In addition, flat surfaces 14, 14 are formed on the upper and lower surfaces of the outer periphery on the axial front side of the rear pen barrel 11. As described later, when the flat surfaces 14, 14 are held by fingers, it is possible to write (mark) directly without changing the holding position, that is, the flat surfaces 14, 14 serve as holding indication surfaces for easily judging the direction of the flat pen tip 20.

[0053] (Front pen 16)

[0054] like Figure 1 to Figure 4 As shown, the front pen holder 16 is composed of a substantially circular cylindrical body, and at least comprises: a flange portion 16a located at a position close to the rear of the central portion; a rear portion 16b located on the rear side of the flange portion 16a and having a fitting step portion; a front portion 16c located on the front side of the flange portion 16a and having a fitting step portion; an inclined opening portion 16d located on the top side of the front portion 16c; a protrusion (not shown) located in the inclined opening portion 16d for accurately directing the ink guide portion 26 toward the central portion of the cotton core 17 serving as an absorbent body; and an annular abutment portion (not shown) for abutting against the rear end portion of the holder 30. In addition, reference numeral 16a1 is a slightly inclined surface portion corresponding to the plane 14 of the rear pen holder 11 at the rear end surface of the flange portion 16a, so as to align with the rear pen holder 11.

[0055] The writing tool body 10 composed of the front pen body 16 and the rear pen body 11 is formed of a thermoplastic resin, a thermosetting resin, etc., for example, a resin composed of polypropylene, etc. is used to form the above structure, and functions as a writing tool body (stick body). The writing tool body 10 is formed to be opaque or transparent (and translucent), but from the perspective of appearance and practicality, either one may be adopted.

[0056] (Cotton core 17)

[0057] The cotton core 17 serves as an ink absorber and is impregnated with an ink composition for writing instruments such as water-based ink, oil-based ink, and thermochromic ink. In the present disclosure, the cotton core 17 is composed of a cotton core having two or more pore size distributions.

[0058] Figure 5 (a) is a front view showing an example of the cotton core 17, Figure 5 (b) using longitudinal section Figure 5 The cotton core 17 of (a) is a schematic diagram showing a state in which two or more pore size distributions are present.

[0059] The cotton core 17 has two or more pore size distributions and has an outer skin 17a made of a resin film on the outer peripheral side. Reference numeral 17b is a first pore size portion, and the outer peripheral side of the first pore size portion 17b is a second pore size portion 17c.

[0060] Whether the cotton core 17 has two or more pore size distributions can be verified, for example, by (1) different pore distributions obtained by a mercury porosimeter, (2) different distributions of inscribed circle diameters obtained by cross-sectional image analysis, (3) different distributions of equivalent diameters of pores obtained by cross-sectional image analysis, etc.

[0061] In the measurement using a mercury porosimeter, the pores in the cotton core are measured using the mercury porosimeter, and confirmation can be performed by finding the difference in the distribution of the pores.

[0062] The pore distribution of a normal cotton core without pore size distribution is roughly unimodal. In contrast, a cotton core with two or more pore size distributions is considered to have two peaks, that is, the pore distribution is bimodal. The bimodal pore distribution means that there are thin parts and thick parts in the pores in the cotton core. It is just a distribution that shows the state of the pores, which is different from the sparse and dense states of the previous cotton core. The sparse and dense states in the past indicate the difference in the volume ratio of pores to fibers (the same applies to the area ratio of the cross section).

[0063] On the other hand, the capillary force generated by the cotton core and the ink is determined by the size of the pores. In order to improve the ink diffusibility, it is necessary to set a portion with lower capillary force and a portion with higher capillary force in the cotton core, which (essentially not coarse or dense) is obtained by the size of the pores.

[0064] In the measurement using a mercury porosimeter, the presence or absence of pore size distribution in the cotton core can be determined by counting the number of peaks of the following pore distribution.

[0065] Regarding the peak number of pore distribution, in the case of a mercury porosimeter, mercury is impregnated into the cotton core by pushing, and the distribution of the equivalent diameter of the pores is obtained from the pressure and the impregnation volume. The equivalent diameter of the pores and their frequency graphs obtained are subjected to peak separation. Peak separation is a common method, but in this study, peak separation based on the "Japan Institute of Energy" was used.

[0066] Through the above analysis, the pore size distribution of the cotton core is peak separated. Since the peak position after separation is expressed in logarithms, it is returned to the original value. Based on the results, the distance between the peaks is calculated, and the half of the half-value width of the component peak is calculated and the sum is calculated. Since the distance between the peaks is less than the sum of half the peak width, there is no pore distribution when the two peaks are separated and cannot be observed.

[0067] In contrast, for a cotton core having two or more pore size distributions, the number of peaks of the pore distribution can be calculated in the same manner as described above for confirmation, that is, using the results of peak separation, based on the relationship between the distance between component peaks and each line width, it can be confirmed that there are double peaks in the cotton core, i.e., two pore size distributions.

[0068] In addition, by measuring the distribution of the inscribed circle diameter by cross-sectional image analysis, it is possible to measure whether or not there is a pore size distribution in the cotton core.

[0069] The presence or absence of pore size distribution can be observed by performing image analysis on the cross section of the cotton core. Specifically, the cut surface of the cotton core is observed, and the pore size (distribution of diameters of inscribed circles) can be obtained from the image analysis.

[0070] In the measurement method, a curable resin (ene-thiol resin photocurable adhesive: manufactured by NITICA) is injected into the obtained cotton core to cure it. Then, it is cut in the direction perpendicular to the axis, the cross section is polished, and the cut surface is observed and photographed using an optical microscope (VHX-8000 manufactured by Keyence). Image analysis (GeoDict manufactured by Math2Market, a comprehensive software package for material development) is performed to decompose the fiber part and the pore part (resin impregnation part). When the largest circle distribution inscribed in the pore part is obtained, it is considered that the pore diameter of 90 μm is the boundary to show the characteristics.

[0071] In a cotton core with a pore size distribution, the frequency of pores smaller than 90 μm is high. If the frequency distribution is analyzed by dividing the inscribed circle into less than 90 μm and the inscribed circle of 90 μm or more, the frequency of the sample is higher (dense part) in the area with a radius of 0.5 mm from the center for the frequency of less than 90 μm, and the frequency of the sample is lower in the area with a radius of 0.5 mm from the center for the frequency of more than 90 μm. According to the above analysis, in a cotton core with a pore size distribution, when the frequency of pores smaller than 90 μm is high, it is judged that there is a distribution of pore sizes. In the area with a radius of 0.5 mm from the center, it is preferred that the frequency of pores smaller than 90 μm is higher. In a cotton core with a pore size distribution, the frequency of pores smaller than 90 μm (thin part) is higher in the radial center, but the location of the thin part can also be the circumference. As described above, when the diameter distribution of the inscribed circle of the pores in the cotton core varies in a certain area, it can be known that the cotton core has a pore diameter distribution.

[0072] Furthermore, by measuring the distribution of equivalent diameters of pores by cross-sectional image analysis, it is possible to verify a cotton core having two or more pore diameter distributions.

[0073] Observe the cross section of the cotton core and analyze the image to find the distribution of the equivalent diameter of the pores. Improve the resolution of the cross-sectional image of the above measurement method to find the fiber perimeter (l) and the area (s) of a certain space (e.g., a square area of ​​1×1 mm). The pores are not circular but irregular in shape, but based on their perimeter and area, the diameter (2r: equivalent diameter) when regarded as a circle can be found by the following formula.

[0074] Circumference of a circle / area of ​​a circle = 2πr / πr2 = 2 / r = l / s = circumference of fiber / area of ​​space

[0075] If the equivalent diameter of the pores in the above-mentioned tiny area is calculated, the equivalent diameter of the "fine" (dense) area is smaller, and the equivalent diameter of the "coarse" (sparse) area is larger. Originally, the capillary force is expressed by l / s×γ (surface tension)×cosθ (contact angle) and is determined by the circumference of the pore and its area. It can be seen that the equivalent diameter of the "fine" (dense) area in the cotton core is smaller, and the equivalent diameter of the "coarse" (sparse) area is larger. When the diameter distribution of the inscribed circle of the pores in the tiny area is different in a certain area, it can be seen that it is a cotton core with a pore diameter distribution. From the perspective of the capillary force distribution in the cotton core, this analysis is essential.

[0076] By any one of the above (1) to (3), a cotton core having two or more pore size distributions can be verified.

[0077] Preferably, based on operability, measurement accuracy, measurement man-hours, etc. (compared with (3), the observation image of (2) can be less. Even if the resolution is lower, the visibility does not decrease), it is expected to measure the distribution of the inscribed circle diameter by using the image analysis of the cross section of (2) to measure the presence or absence of pore size distribution in the cotton core.

[0078] In order to obtain the above-mentioned cotton core with two or more pore size distributions, for example, fibers having different fiber volume density, fiber diameter, fiber material, fiber morphology, fiber surface tension, and capillary force can be used for the cotton core, or two or more of them can be appropriately combined to produce it.

[0079] As the fibers that can be used, for example, natural fibers, animal hair fibers, polyacetal resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl alcohol resins, polycarbonate resins, polyether resins, polyphenylene resins, etc., one or a combination of two or more thereof can be cited.

[0080] Specifically, as an example, it can be produced as follows.

[0081] After the fibers were bundled, a fiber bundle having a second pore size distribution was inserted into the center of the fiber bundle having the first pore size distribution, and a polypropylene cylinder having a length of 80 mm and an inner diameter of 6 mm was used to simulate a pen holder, and the cotton cores of the following embodiments and comparative examples were filled therein, and used for the following experiment. For the fiber bundle, the polyester fibers were compressed and bundled, and the weight was measured in a manner that the ratio of the dense part was specified. By filling the polypropylene cylinder, a cotton core for a writing instrument having the above-mentioned pore size distribution characteristics of two or more pore size distributions can be obtained.

[0082] (Writing ink)

[0083] The composition of the writing ink used is not particularly limited. Depending on the purpose of the writing instrument, a preferred mixed formula of water-based ink, oil-based ink, thermochromic ink, etc. can be adopted. For example, for underline pens, the ink can contain fluorescent pigments such as basic violet 11, basic yellow 40, thermochromic microcapsule pigments, etc.

[0084] Preferably, a resin microparticle pigment ink composition containing a dye is desired.

[0085] As a resin particle pigment ink containing a dye, there can be listed a resin particle pigment ink containing at least the following components: a water-soluble organic solvent; water; and a dispersion of colored resin particles, the dispersion being prepared by dispersing the colored resin particles in water, the colored resin particles being colored resin particles composed of a cyclohexyl (meth)acrylate monomer and a basic dye or an oil-soluble dye, and the content of the cyclohexyl (meth)acrylate monomer being 30% by mass or more relative to the total polymer components constituting the colored resin particles, and the content of the basic dye or the oil-soluble dye being 15% by mass or more relative to the total polymer components.

[0086] In addition, for these ink compositions, by adjusting the types of ink mixing components and the mixing amounts of each component, the ink viscosity (25°C: cone and plate viscometer) can be set to 1 to 5 mPa·s, and the surface tension can be set to 30 to 60 mN / m. In addition, the ink outflow from the pen tip 20 and the pen tip 40 of a marker-type writing instrument can be easily combined with the characteristics of the cotton core for writing instruments disclosed in the present invention to set the ink outflow to a preferred range, which is set to 5 to 20 mg / m in the present embodiment.

[0087] In addition, in the case of using an ink composition containing a thermochromic microcapsule pigment, for example, Figure 1As shown in (c) and (d) of FIG. 5 , a friction body 53 made of a cylindrical thermoplastic elastomer having an erasing capability (erasing rate) of less than 70% for pencil lines as specified in Japanese Industrial Standard JIS S6050-2002 can be fixed to the concave portion 52 of the pen cap 50. By making the friction body 53 easy to generate friction heat and low in wear by rubbing action, the generation of eraser residue during friction can be reduced to prevent contamination of the surroundings. In addition, the vent hole 54 is a vent hole for facilitating the installation and removal of the friction body 53.

[0088] (Pen tip 20)

[0089] like Figure 1 to Figure 7 As shown, the pen tip 20 includes at least a writing part 25, an ink guide part 26 that guides the ink of the writing tool body 10 to the writing part 25, and a retaining body 30 having a visible part. The writing part 25 and the ink guide part 26 are installed on the retaining body 30 by bonding, welding, embedding, etc.

[0090] The writing portion 25 is inclined (knife-cut) so that the upper side of the rectangular base portion is inclined for easy writing. The inclination of the writing portion 25 is appropriately set according to the comfort of writing. Figure 7 As shown in (a) to (d), the writing part 25 has a writing part 25a, which has a larger width W1 of the drawing line, and a writing part 25b, which has a smaller width W2 of the drawing line, in a manner capable of adjusting the drawing line width. The writing part 25 can adjust (select) the drawing line width W1 and the drawing line width W2 by tilting the axis. In this form, W1:W2 is a ratio of 2:1 or more. The drawing line width W1 is 2.0 to 5.0 mm, and the drawing line width W2 is 1.0 to 2.5 mm.

[0091] As the material of the writing part 25, for example, a porous body with pores can be cited, specifically, a sponge, a sintered body, a fiber bundle body, a foamed body, a sponge, a felt body, a porous body, etc. As the material forming these porous bodies, for example, natural fibers, animal hair fibers, polyacetal resins, polyethylene resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl alcohol resins, polycarbonate resins, polyether resins, polyphenyl resins, etc. can be used. In order to make the pen feel better, the writing part 25 of this embodiment is composed of a sintered core formed by sintering plastic powder (for example, PE).

[0092] The ink guide 26 is thin-plate-shaped and has an inclined portion 26a at the rear side. From the viewpoint of maximizing (widening) the area of ​​the visible portion, the ink guide 26 preferably has a rectangular or elliptical cross section. In the present embodiment, the cross section is rectangular.

[0093] The ink guide 26 is not particularly limited as long as it efficiently guides (supplies) the ink absorbed by the cotton core 17 in the writing instrument body 10 to the writing part 25 through the ink guide 26. For example, it can be a member made of a material having liquid permeability such as a non-woven fabric, a textile or a knitted fabric, a fiber bundle core, or a liquid permeable foam, a sintered body, etc. In addition, the writing part 25 and the ink guide 26 can also be integrally formed of a single material, but it is preferred that different members are connected or combined with each other or connected or combined via a retaining body as described later from the perspective of further exerting the effects of the present disclosure, efficiently supplying ink, and making the writing part feel better.

[0094] In the present embodiment, "nonwoven fabric" refers to a material in which a block of one or more layers of fibers is formed into a cloth-like structure without being woven. As raw materials for the fibers, synthetic fibers, natural fibers, animal hair fibers, inorganic fibers, etc. can be used. As materials for the synthetic fibers used, for example, one or a combination of two or more of polyacetal resins, polyethylene resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl alcohol resins, polycarbonate resins, polyether resins, polyphenyl resins, etc. can be cited.

[0095] The fibers constituting the fabric can be obtained by known methods, for example, melt spinning, dry spinning, wet spinning, direct spinning (melt blowing, spunbonding, electrospinning, etc.), a method of extracting fibers with a finer fiber diameter by adsorbing one or more resin components from composite fibers, and a method of obtaining divided fibers by detangling fibers.

[0096] Furthermore, the fibers constituting the fabric may be composed of one or more resin components, and what are generally called conjugate fibers, for example, core-sheath type, island-in-the-sea type, side-by-side type, segmented-segment type, etc. conjugate fibers may be used.

[0097] The fineness of the fibers constituting the fabric is not particularly limited, but is preferably 0.1 to 500 dtex (dtex), more preferably 2 to 5 dtex (dtex). The fiber length is also not particularly limited, and short fibers, long fibers, or continuous fibers can be used.

[0098] When the fabric is a woven fabric or a knitted fabric, it can be prepared by spinning or knitting the fibers prepared as described above.

[0099] In the case where the fabric is a non-woven fabric, as a method for preparing a fiber web that can produce a non-woven fabric, for example, a dry method, a wet method, etc. can be used. Moreover, as a method for entanglement and / or integration of the fibers constituting the fiber web to form a non-woven fabric, for example, a method of entanglement using a needle-shaped piece or a water flow, a method of integrating the fibers with each other using a binder, or a method of integrating the fibers with each other by heating the fiber web to melt the thermoplastic resin when the fiber web contains a thermoplastic resin. In addition, as a method for heating the fiber web, for example, a method of heating and pressurizing using a calender roll, a method of heating using a hot air dryer, a method of melting the thermoplastic resin fiber by irradiating infrared rays in a non-pressure state, etc. can be used. In addition, a non-woven fabric can also be prepared by capturing fibers spun using a direct spinning method.

[0100] Examples of fiber bundle cores include those obtained by processing parallel fiber bundles composed of the raw materials of the above fibers (synthetic fibers, natural fibers, animal hair fibers, inorganic fibers, polystyrene resins, etc., or a combination of two or more thereof) or by subjecting these fiber bundles to resin processing.

[0101] In the case of a liquid-permeable foam, for example, it can be prepared by injecting a molten resin into a mold and performing molding, foaming, and other known methods. In addition, as a sintered body, it can be composed of a porous body (sintered core) formed by sintering plastic powders such as polyacetal resins, polyethylene resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl alcohol resins, polycarbonate resins, polyether resins, and polyphenyl resins.

[0102] The shape and thickness of the ink guide portion 26 can be set according to the installation form on the retaining body 30, the shape of the writing portion 25, the maximization of the visible area of ​​the visible portion, and the efficient outflow (supply) of ink to the writing portion 25. Preferably, the width direction length and the length direction length become the approximate width direction length and the approximate length direction length of the mounting surface of the retaining body 30 to which the thin plate-shaped ink guide portion 26 is fixed, respectively, so that the ink can flow efficiently to the writing portion 25. Figure 4 As shown in (b), from the perspective of maximizing the visible area of ​​the visible portion, the thickness t of the thin plate-shaped ink guide portion 26 (the width when viewed in a direction perpendicular to the visible surface) is preferably less than 1.5 mm, more preferably less than 1.2 mm, and particularly preferably less than 0.8 mm. From the perspective of better ink supply, productivity, etc., the lower limit value is expected to be greater than 0.5 mm.

[0103] In this embodiment, from the perspective of being able to efficiently flow ink using a smaller cross-sectional area, the ink guide portion 26 is composed of a PET fiber bundle core with a rectangular cross-section, with a length of 20 mm in the longitudinal direction, a length of 2 mm in the width direction, and a thickness t of 0.8 mm.

[0104] The rear end 26a of the ink guide 26 is inserted into the front end of the cotton core 17, and the front end 26b contacts the writing part 25 via the holder 30. With this structure, the ink in the cotton core 17 is efficiently supplied to the writing part 25 in an appropriate amount via the ink guide 26 by capillary force.

[0105] (Retaining body 30)

[0106] like Figure 2 to Figure 7 As shown, the retaining body 30 fixes the above-mentioned writing part 25 and ink guide part 26, and its rear end side is fixed in the inclined opening part 16d of the front pen shaft 16 of the writing tool body 10, and the retaining body 30 has a bulging main body part 31, a flange part 32 located on the front side of the main body part 31 and abutting against the end face of the writing tool body 10, and a visible part 33 that can visually confirm the writing direction, and, at the top end side of the visible part 33, there are front retaining parts 34a, 34b for retaining the top end side (end face) of the writing part 25, and anti-detachment parts 34c, 34d for receiving the end face of the writing part 25 provided at one end of each retaining part.

[0107] In addition, a rear holding portion 35 connected to the main body 31 is provided on the bottom surface side of the rear side of the main body 31. From the perspective of maximizing the visual confirmation area of ​​the visible portion 33, a structure mounted (arranged) on the bottom surface of the holding body 30 in the longitudinal direction is formed as a whole on the bottom surface side of the holding body 30 composed of these components. Specifically, a concave holding groove 36 is formed as a whole on the bottom surface in the longitudinal direction of the holding body 30 to fit and hold the thin plate-shaped (rectangular cross-section) ink guide 26. In addition, a concave fitting portion 31a is formed on the outer peripheral surface in the width direction of the main body 31.

[0108] Furthermore, ribs 37, 37 ..., 38, 38 ... are formed at predetermined intervals in the direction perpendicular to the axis on the surfaces with which the writing part 25 and the ink guide part 26 contact, on both sides of the concave holding groove 36 for fixing the writing part 25 and the concave holding groove 36 for fixing the ink guide part 26, thereby making it possible to stably assemble the writing part 25 and the ink guide part 26, which are easily damaged and which have dimensional deviations due to the forming process, to the holding body 30. In the present embodiment, the length of the mounting surface 36a of the holding groove 36 in the width direction is set to be slightly shorter than the length of the top end side 26b of the ink guide part 26 in the width direction, thereby increasing the fixing force by pressing and fitting the top end side 26b of the ink guide part 26 into the holding groove 36a and reliably maintaining the connection with the writing part 25.

[0109] The thin plate-shaped ink guide portion 26 is fixed to the mounting surfaces 36 a and 36 b of the holding groove 36 of the holding body 30 by bonding with an adhesive, welding, or the like, and is fixed to the writing portion 25 .

[0110] In the writing tool A, in order to embed and retain the writing part 25 between the front retaining parts 34a and 34b, and to reliably fix (prevent the writing part 25 from falling off), the writing part 25 can be further fixed (installed) to the retaining body 30 by bonding, welding, etc. using an adhesive.

[0111] In addition, air circulation grooves 39, 39 are formed on the outer peripheral surface in the longitudinal direction of the main body 31, so that even if the air pressure in the writing tool increases, it can be adjusted using the air circulation grooves 39, 39, and ink leakage can be eliminated.

[0112] The ink guide portion 26 is composed of a fiber bundle core having a rectangular or elliptical cross-section, and in the present embodiment, a rectangular cross-section. The writing portion 25 is composed of a resin sintered body. The writing portion 25 and the ink guide portion 26 are fixed to the retaining groove 36, mounting surfaces 36a, 36b of the retaining body 30, and the ink guide portion 26 and the writing portion 25 are pressed and fixed, so that the ink from the cotton core 17 is well supplied to the writing portion 25 via the ink guide portion 26.

[0113] The retaining body 30 thus constructed is entirely made of a hard material, for example, a hard material that can be visually confirmed, such as glass, a resin that does not have rubber elasticity, etc. As a resin that can be visually confirmed that does not have rubber elasticity, for example, by forming a material having a visible light transmittance of 50% or more, such as PP, PE, PET, PEN, nylon (including amorphous nylon in addition to common nylons such as 6 nylon and 12 nylon), acrylic acid, polymethylpentene, polystyrene, ABS, etc., it is possible to effectively visually confirm the text written along the writing direction using the visible portion 33. In addition, only the visible portion 33 can be made of a material that can be visually confirmed. In addition, the visible light transmittance can be obtained by measuring the reflectivity using a multi-light source spectrophotometer [manufactured by Suga Test Instruments Co., Ltd. (MSC-5N)].

[0114] The retaining body 30 may be made of one of the above-mentioned materials, or may be made of two or more materials in order to further improve durability and visual confirmation. The retaining body 30 may be formed by various molding methods such as injection molding and blow molding.

[0115] In this embodiment, if Figure 3 As shown in (b), the minimum width S of the visible portion 33 of the holder 30 in the width direction is 3.7 mm or more, and the length Y of the visible portion 33 is set to 7.4 mm or more. In this embodiment, the width S is expanded as the width goes from the top side of the visible portion 33 of the holder 30 to the rear side, and the minimum width S is the length in the width direction of the top side of the visible portion 33 of the holder 30, and the width (parallel to the pen tip) is 3.7 mm or more. In addition, in this embodiment, the maximum width of the visible portion 33 in the width direction is 4.5 mm.

[0116] By setting the minimum width S to 3.7 mm or more, a 10.5 point (size 5 font) printed on the paper can be fully visually recognized by the visible portion 33. Generally, size 5 font is often used as a standard in ordinary documents in Japan.

[0117] In addition, the length Y of the visible portion 33 is twice the minimum width S, that is, 7.4 mm or more. For example, when the writing angle is 60°, the 3.7 mm wide text can be contained in the visible portion 33 even when viewed from above (3.7 mm / cos60°=7.4 mm).

[0118] In order to set the minimum width S of the visible portion 33 to be greater than 3.7 mm and the length Y to be greater than 7.4 mm, the setting can be achieved by constructing (determining) the structure and shape of the various components of the pen tip 20 (writing portion 25, ink guide portion 26, retaining body 30) as described above and preferably combining them.

[0119] Moreover, in the present embodiment, from the perspective of ensuring the guidance of a sufficient and necessary ink flow to the writing portion 25 and further expanding the area of ​​the visible portion 33 that can be visually confirmed, the width (length when observed in a direction perpendicular to the surface of the visible portion 33) t of the ink guide portion 26 is less than 1.5 mm, more preferably less than 1.2 mm, and particularly preferably less than 0.8 mm.

[0120] In addition, the ink guide portion 26 is fixed by being embedded in the concave retaining groove 36, the mounting surfaces 36a, 36b, etc., and from the perspective of efficient assembly, productivity, etc., its side surface is not a structure that covers the entire ink guide portion 26, but is a shape that is open to the external air surface. Therefore, it becomes the following structure: the overall width of the ink guide portion 26 including the width t is made the necessary minimum, and the width S of the visible portion 33 is made the maximum.

[0121] In addition, if Figure 3 As shown in (b), by providing one ink guide portion 26 on one side of the visible portion 33, that is, by arranging the ink guide portion 26 on the near front side (the side where the pen tip 20 forms an obtuse angle with respect to the ink guide portion 26) when writing, the ink guide portion 26 will not affect the text in the traveling direction even when writing at a natural writing angle, and the visual field of the visible portion 33 is better. If the ink guide portion 26 is not arranged on the near front side when writing, but arranged on the back side (upper side), then when writing (marking), the ink guide portion 26 crosses the text in the traveling direction and partially covers the text. In this respect, the action mechanism of the visible portion 33 is different.

[0122] Then, if Figure 1 As shown in (c) and (d), the pen tip 40 for writing fine characters is a rod-shaped pen tip for writing fine characters, and its cross-section is circular. The rear end (cotton core side) of the pen tip 40 is inserted into the cotton core 17, and the ink of the cotton core 17 is supplied to the pen tip 40 by capillary force.

[0123] The pen tip 40 is composed of a porous component, for example: a parallel fiber bundle composed of one or a combination of two or more of natural fibers, animal hair fibers, polyacetal resins, polyethylene resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl alcohol resins, polycarbonate resins, polyether resins, polyphenylene resins, etc.; a fiber core formed by processing fiber bundles such as felt or resin processing these fiber bundles; or a component composed of a porous body (sintered core) formed by sintering plastic powders of thermoplastic resins such as polyolefin resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, etc.

[0124] The preferred pen tip 40 is a fiber bundle core, a fiber core, a sintered core, a felt core, a sponge core, or an inorganic porous body core. It is particularly preferred that it is a fiber core from the viewpoint of deformation formability and productivity. In addition, the porosity, size, hardness, etc. of the pen tip 40 used vary depending on the type of ink, the type of writing tool, etc. For example, the porosity is preferably set to 30 to 60%. In addition, in the present disclosure, the "porosity" of the writing core is calculated in the following manner. First, a writing core with a known mass and apparent volume is immersed in water, and after it is fully soaked in water, the mass is measured after it is taken out of the water. Based on the measured mass, the volume of water immersed in the writing core is derived. The volume of the water is regarded as being the same as the pore volume of the writing core, and the porosity is calculated according to the following formula.

[0125] Porosity (unit: %) = (volume of water) / (apparent volume of pen tip 40) × 100

[0126] In the writing tool A thus constructed, the cotton core for writing tools of the present invention which absorbs the writing tool ink, that is, the cotton core 17 having the characteristics of having two or more distributions of pore diameters and a first pore diameter of 50 to 300 μm and a second pore diameter of 50 to 90% of the first pore diameter, is inserted into and retained in the writing tool body 10, and at the top end side, the nib 20 (writing part 25, ink guide part 26, retaining body 30) of the above structure is fixed in sequence via the front pen shaft 16 by means of interlocking, and at the other end side, the retaining member 45 to which the nib 40 is fixed is fixed by means of interlocking, thereby making it possible to simply manufacture a dual-type writing tool A, and the ink absorbed in the cotton core for writing tools of the present invention 17 is efficiently supplied to the writing part 25 and the nib 40 at the nib 20 via the thin plate-shaped ink guide part 26 by means of capillary force, so that a cotton core for writing tools that can further improve the ink diffusibility and a writing tool using the cotton core for writing tools can be obtained.

[0127] In this writing tool A, the pen tip 40 is the same as a conventionally used pen tip, and therefore the functions of the pen tip 20 and the like will be described below.

[0128] like Figure 1 to Figure 4 As shown in the figures, the pen tip 20 of the writing tool A has a visible portion (window portion) 33 for visually confirming the writing direction, and the ink of the cotton core 17 of the writing tool disclosed in the present invention reaches the writing portion 25 and the pen tip 40 respectively by the capillary force of the cotton core 17, and is provided for writing. When writing, if the visual confirmation side is observed by using the visible portion (window portion) 33, it is easy to align the position where the line is started, and it is possible to stop immediately at the part where the line is to be stopped at the end, which can prevent the line from being drawn excessively or exceeding.

[0129] The pen tip of the above-mentioned embodiment includes at least a writing portion 25 capable of selecting two line widths, a retaining body 30 having a visible portion 33, and an ink guide portion 26 for guiding the ink of the writing tool body 10 to the writing portion. By using a structure in which the minimum width (S) of the visible portion 33 is set to be greater than 3.7 mm and the length (Y) of the visible portion 33 is set to be greater than 7.4 mm (hereinafter, this structure is referred to as "Structure 1"), or by using a structure in which the ink guide portion 26 is arranged on the near front side when writing, that is, when the pen tip 20 is fixed to the retaining body 30, the ink guide portion 26 is arranged on the near front side when writing (the side where the pen tip 20 forms an obtuse angle with respect to the ink guide portion 26) (hereinafter, this structure is referred to as "Structure 2"), it is possible to achieve a high degree of both ease of writing and maximization of the effective area of ​​the visible portion 33 that can visually confirm the writing direction and ease of visibility.

[0130] In the above-mentioned structure 2, even when writing at a natural angle, the ink guide 26 does not affect the text in the traveling direction, and the visual field of the visible portion 33 is better. If the ink guide 26 is not arranged on the near front side but on the back side (upper side) when writing, or is arranged in the shape of a Japanese kana letter U or a letter U with two ink guides on both sides of the writing portion, when writing (marking), the ink guide crosses the text in the traveling direction and partially covers the text. In this regard, the function mechanism of the visible portion 33 is different. In this form, it is also possible to take into account the ease of writing and the maximization of the effective area of ​​the visible portion 33 and the ease of visibility to a high degree. By using the widened visible portion 33, the writing direction is clearer and the ease of writing is further improved.

[0131] By setting the width t of the ink guide portion 26 to be less than 1.2 mm when viewed from a plane perpendicular to the visible portion 33 (hereinafter referred to as "Structure 3"), the area of ​​the visible portion can be further maximized, and the effects of the present disclosure can be further achieved to a higher degree.

[0132] In addition, the ink guide portion 26 is composed of a fiber bundle core whose cross-section is a rectangular or elliptical shape, and the writing portion 25 is composed of a sintered body made of resin, and the ink guide portion 26 and the writing portion 25 are fixed to the retaining body 30, and the ink guide portion 26 abuts against the end of the writing portion 25. By setting such a structure (hereinafter, this structure is referred to as "Structure 4"), the ink guide portion 26 can utilize a smaller cross-sectional area to efficiently flow (supply) ink to the writing portion 25, resulting in a good pen-moving feel, and can further take into account the effects of the present disclosure to a higher degree.

[0133] Moreover, the writing tool A has good ink outflow properties through the cotton core 17 for writing tools disclosed in the present invention, in which the pore diameter has two or more distributions, the first pore diameter is 50 to 300 μm, and the second pore diameter is 50 to 90% of the first pore diameter. Therefore, a writing tool such as the following is obtained: even if the moving speed of the pen tip 20 (or the pen tip 40) is increased for writing, the ink supply will follow well, and there will be no discontinuity in the handwriting.

[0134] The writing instrument of the present embodiment is not limited to the above-described forms and the like, and various modifications can be made.

[0135] For example, in the cotton core for writing instruments of the above-mentioned form, a fiber bundle core without a window portion or oily ink may be provided. In addition, a ballpoint pen tip may be provided instead of a marker pen tip.

[0136] In the writing tools of the above-mentioned embodiments, each writing tool is composed of the above-mentioned structure 1 or structure 2, but each writing tool can also be composed of a structure formed by combining structures 1 and 2 and a structure formed by combining the above-mentioned structure 3 and / or structure 4 in the structure of structure 1 or structure 2.

[0137] In addition, in the above-mentioned embodiment, in the writing tool of structure 1, as a preferred form, it is set to have a structure with an ink guide portion 26 on one side of the visible portion 33, but in the structure of structure 1, even if there is a structure in which two ink guide portions 26 are further provided on the upper and lower surfaces of the visible portion 33 (two ink guide portions 26 that are integrated or independent components are provided on both sides of the writing portion 25, and 26 are in the shape of the Japanese kana letter U or the letter U), although the text in the direction of travel will be crossed when writing (marking), the effect of the present invention can be exerted in the structure of the unprecedentedly wide visible portion 33, that is, the minimum width (S) of the visible portion 33 is set to be greater than 3.7 mm and its length (Y) is greater than 7.4 mm.

[0138] In addition, in addition to fixation by embedding into the retaining body 30, the fixing method between the retaining body 30 and the writing part 25 and the ink guide part 26 can also be carried out by fixing with hot-melt adhesives, fixing by solvent penetration, fixing by ultrasonic welding, fixing with reaction-based adhesives (moisture curing, UV curing, oxygen curing, two-liquid curing), fixing with solvent-based adhesives (soluble synthetic resins, emulsions, rubbers), adhesive tapes, and fixing with double-sided tapes.

[0139] The porosity of the writing part 25 is preferably set to the following range.

[0140] Preferably, the porosity is set to 30 to 80%, more preferably 40 to 70%.

[0141] Furthermore, in the writing tool A disclosed in the present invention, a double-type writing tool is shown, but it can also be set as a single-type writing tool with a pen tip 20 by omitting the pen tip 40 (setting the rod body to a bottomed cylindrical rod body), and also can be a writing tool in which the pen tip 20 is protruded and retracted by pressing.

[0142] In the writing implement A of each embodiment described above, the cross section of the rod body of the writing implement body is formed into a circular rod, but it can also be set to a triangular shape, a square shape larger than a quadrilateral, or an elliptical shape. In addition, the case where the pen tip 20 is composed of a transparent member as a whole is shown, but the pen tip 20 can also be composed of the following members: at least the visible part 33 is composed of a transparent member, and the part on the side of the main body 31 installed in the writing implement body is composed of a resin member other than the transparent member, so as to form a two-color molded product.

[0143] Furthermore, in the above-mentioned embodiments, the ink for writing instruments (water-based ink, oil-based ink, thermochromic ink) is described, but liquid substances such as liquid cosmetics, liquid medicines, coating liquids, and correction fluids may also be used.

[0144] Example

[0145] Next, the present disclosure will be described in further detail using Production Examples, Examples, and Comparative Examples, but the present disclosure is not limited to the following Production Examples and the like.

[0146] [Manufacturing Example 1: Manufacture of Cotton Core (Sample) A]

[0147] For the cotton core A, 5d (denier, the same below), 650 strands and 3d, 460 strands manufactured by Toray Industries, Inc. were used. After bundling, a fiber bundle having a second pore size distribution was inserted into the center of the fiber bundle having the first pore size distribution. A polypropylene cylinder with a length of 80 mm and an inner diameter of 6 mm was used to simulate a pen holder, and the cotton cores of the following embodiments and comparative examples were filled therein for the following experiment. For the fiber bundle, the polyester fiber was compressed and bundled, and the weight was measured in a manner that the ratio of the dense part was specified. The fiber bundle was filled in a polypropylene cylinder to produce a cotton core A having a first porosity, a second porosity, and two pore size distributions that became the porosity ratio.

[0148] For the cotton core B, 15,300 fibers of 3 denier manufactured by Toray Industries were bundled and used as pen holders in a polypropylene cylinder with a length of 80 mm and an inner diameter of 6 mm. The fiber bundle was compressed and bundled, and the weight was measured so that the ratio of the dense part was a predetermined ratio. The fiber bundle was filled in a polypropylene cylinder to produce a cotton core B having a pore size distribution that was the first porosity.

[0149] The presence or absence of pore size distribution was verified for the cotton cores (samples) A ​​and B obtained in the above-mentioned Production Examples 1 and 2 by the following measurement method.

[0150] [Measurement method: Measurement of the distribution of inscribed circle diameters using cross-sectional image analysis]

[0151] The pore distribution was measured based on the results of optical microscope observation of cotton cores (samples) A ​​and B as test samples. The device and measurement conditions used are as follows.

[0152] Device name: Material development comprehensive software package Math2Market GeoDict Nissan Arc Development Program (for Fig.13 )

[0153] Measurement item: Diameter of the largest inscribed circle relative to the hole

[0154] Measurement conditions: Optical microscope images were input into an image analyzer and binarized to separate fibers and pores. Then, the diameter of the largest inscribed circle of the pores was measured. Due to the number of data points, the moving average was used for the pore size distribution.

[0155] The presence or absence of pore size distribution is observed by performing image analysis on the cross section of the cotton core A. Specifically, the cross section of the cotton core A is observed and the pore size (distribution of diameters of inscribed circles) is determined by the image analysis.

[0156] In the measurement method, a curable resin (ene-thiol resin-based photocurable adhesive: manufactured by NITICA) is injected into the obtained cotton cores A and B to cure them. Next, the samples are cut in a direction perpendicular to the axis, the cross section is polished, and the samples are observed and photographed using an optical microscope (VHX-8000 manufactured by Keyence). Image analysis (GeoDic, a comprehensive material development software package manufactured by Math2Market) is performed to decompose the fiber portion and the void portion (resin-impregnated portion). The distribution of the largest circle inscribed in the void portion is obtained for both samples A and B, and the results are as follows. Figure 8 to Figure 24 The results shown.

[0157] Figure 8 and Fig. 9 These are the optical microscope cross-sectional observations and binarized images of the cotton cores of Manufacturing Examples 1 and 2 (Samples A and B). Fig.10 and Fig.11 It is a pore distribution diagram (the largest circle inscribed in the pore portion) of Production Examples 1 and 2 (Samples A and B). Fig.10 The optical microscope cross-section observation image in the figure is displayed in black and white, but the optical microscope cross-section is originally displayed in four colors: green, yellow, white, and red. Fig.10 , Fig.11 , Figures 15 to 20 In the figure, "yellow" indicates gray in a circular shape, "white" indicates white dots, "red" indicates black dots, and "green" indicates the entire area other than the above "yellow, white, and red". In the following Examples 12 to 20, the same as above is used for black and white display, and the optical microscope cross section is originally a color display of four colors: green, yellow, white, and red.

[0158] Next, Fig.12 This is a graph of the pore size distribution (largest circle distribution inscribed in the pore portion) of Production Examples 1 and 2 (Samples A and B). Fig.13 The accompanying drawings illustrate graphs and measurement methods showing the relationship between the spatial distribution of pores (the distance from the center of the circle and the pore area frequency) of Production Examples 1 and 2 (Samples A and B). Fig.14 This is a graph showing the pore diameter and area frequency after plotting the threshold values ​​of the pore distribution (distribution of the largest circle inscribed in the pore portion) of Manufacturing Examples 1 and 2 (Samples A and B) at 50 μm, 90 μm, and 100 μm, Figures 15 to 20 This is a graph showing the pore distribution (the largest circle inscribed in the pore portion) at thresholds of 100 μm, 90 μm, and 50 μm for Production Examples 1 and 2 (Samples A and B). Fig.21The figures show the relationship between the distance from the circle center (pore diameter is 0 or more and less than 100 μm, pore diameter is 100 μm or more) and the pore diameter frequency of Manufacturing Examples 1 and 2 (Samples A and B), and a figure showing the measurement method. Fig. 22 The figures show the relationship between the distance from the circle center (pore diameter is 0 or more and less than 90 μm, pore diameter is 90 μm or more) and the pore diameter frequency of Manufacturing Examples 1 and 2 (Samples A and B), and the accompanying figure showing the measurement method. Fig.23 The figures show the relationship between the distance from the circle center (pore diameter is 0 or more and less than 50 μm, pore diameter is 50 μm or more) and the pore diameter frequency of Manufacturing Examples 1 and 2 (Samples A and B), and the accompanying drawings showing the measurement method. Fig.24 These are graphs showing the relationship between the distance from the circle center and the pore diameter frequency in Production Examples 1 and 2 (Samples A and B).

[0159] Comprehensive evaluation Figure 8 to Figure 24 The results of each example show the characteristics of the cotton cores (samples A and B) of manufacturing examples 1 and 2, with the pore diameter of 90 μm as the boundary. Figure 12 to Figure 14 , Figure 21 to Figure 24 By comparing the various results, the frequency of pores smaller than 90 μm in the cotton core (sample B) of manufacturing example 2 is higher. If the frequency distribution is analyzed by dividing the inscribed circle smaller than 90 μm and the inscribed circle greater than 90 μm, the frequency of the cotton core (sample A) of manufacturing example 1 is higher (dense part) in the area with a radius of 0.5 mm from the center for the frequency smaller than 90 μm, and the frequency of sample A of manufacturing example 1 is lower in the area with a radius of 0.5 mm from the center for the frequency greater than 90 μm. Based on the above analysis, it is judged that there is a distribution of pore diameters in the cotton core (sample A) of manufacturing example 1, and it is judged that there is no distribution of pore diameters in the cotton core (sample B) of manufacturing example 2. In the cotton core (sample A) of manufacturing example 1, the frequency of pores smaller than 90 μm (thin part) is higher in the radial center, but the location of the thin part can also be the circumference. As described above, when the diameter distribution of the inscribed circle of the pores in the wick differs in a certain region, the presence of the pore size distribution can be confirmed.

[0160] [Example 1 and Comparative Example 1]

[0161] Using the cotton cores (samples) A ​​and B obtained in Manufacturing Examples 1 and 2, the following structures and Figure 1 to Figure 7 A writing instrument having a nib of the following composition and a writing instrument ink having the following composition. The nib size and the like are as shown below.

[0162] [Structure of the pen tip 20 (writing portion 25, ink guide portion 26, holder 30)]

[0163] Writing part 25: Polyethylene sintered core, porosity: 50%, 4×3×6mm, T=3mm, W1=4mm, W2=1.5mm

[0164] Ink guide 26: PET fiber core, width length: 2 mm, length in longitudinal direction: 20 mm, thickness t: 0.8 mm

[0165] Holder 30: Made of acrylic resin, visible light transmittance 85% [The visible light transmittance was determined by measuring the reflectance with a multi-light source spectrocolorimeter (MSC-5N) manufactured by Suga Test Instruments Co., Ltd.]

[0166] Size of visible portion (window) 33 (quadrilateral): S = 3.8 mm (maximum 4.5 mm) × Y = 8 mm × width (thickness) 2.5 mm

[0167] Cotton core for writing instrument: Cotton core A to Cotton core B (φ6×80 mm) obtained in the above-mentioned Production Example 1 and Production Example 2 were used.

[0168] Outer skin: PET film

[0169] Writing tool body 10, pen cap 50, 60: made of polypropylene (PP)

[0170] Pen tip 40: Polyester fiber bundle core, porosity 60%, φ2×40mm

[0171] Friction body 52: a styrene-based elastomer selected from the group consisting of styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), and styrene-ethylene-butadiene-styrene (SEBS)

[0172] (Writing ink composition: Ink color: fluorescent pink)

[0173] As writing ink, an ink having the following composition (total 100 mass %) was used.

[0174] Dispersion: 50% by mass

[0175] Triethanolamine: 2% by mass

[0176] Ethylene glycol: 5 mass%

[0177] Surfactant: 0.5 mass%

[0178] Distilled water: 42.5% by mass

[0179] pH: 4.0

[0180] Viscosity (25°C): 3.5 mPa·s (cone-plate viscometer, TV-20 manufactured by TOKIMEC)

[0181] Surface tension (25°C): 35 mN / m (automatic surface tension meter, Kyowa Interface Science Co., Ltd., DY-300)

[0182] In this use the basis Figure 1 to Figure 7 In the writing tool of the pen tip 20 of the first embodiment, the pore diameter of the cotton core A has two or more distributions, so that ink can be reliably supplied to the pen tip 20, 40, and the ink diffusibility can be improved. In addition, the ink from the cotton core A is guided to the writing part 25 by the thin plate-shaped open ink guide part 26 with flowability. The writing part 25 is composed of a resin sintered core, and the ink guide part 26 is composed of a fiber bundle core. The strength of the capillary force relative to the porosity is large, and the thickness can be very thin, and the ink flowability is good. It is not necessary to design the ink guide part to be thick. The minimum width S of the visible part 33 is 3.7 mm or more, and the length Y thereof is 7.4 mm or more. Therefore, it is possible to achieve both ease of writing and maximization of the effective area of ​​the visible part 33 that can visually confirm the writing direction and easy visibility to a high degree.

[0183] In addition, the ink guide 26 is arranged on the near front side when writing, so even when writing at a natural angle, the ink guide 26 does not affect the text in the direction of travel, and the visual field of the visible portion 33 is better. When a right-handed person writes from left to right, he can use the writing portion 25 to draw lines while visually confirming the writing direction using the visible portion 33, and the ink outflow is also good without impairing the ink outflow, and it was confirmed that a writing tool that can achieve easy writing and significant visibility of the visible portion 33 can be obtained. In addition, it was confirmed that writing can be performed without discontinuity even after falling from a height of 1m above the cedar board.

[0184] Moreover, the writing tool is installed in an automatic writing device, and after writing a straight line on a high-quality paper at a writing angle of 65°, a writing load of 1N, and a speed of 7cm / s in accordance with the test method based on Japanese Industrial Standard JIS S6037, when the state of the written line is visually confirmed, it is judged that: due to the use of the ink of the above-mentioned preferred ink combination components, the following functions are exhibited, namely, the ink flow rate (10mg / m) of the pen tip 20 is also relatively good, while the drying of the pen tip is suppressed, the drying of the line and the low-temperature stability of the ink are also relatively excellent, and the line will not bleed or seep through.

[0185] In contrast, in the writing instrument of Comparative Example 1 equipped with the cotton core B having no pore size distribution, it took more than one hour to supply ink to the pen tips 20 and 40. In addition, among 100 pen tips, 5 pen tips were still not impregnated with ink after one day and could not be supplied with ink.

[0186] Industrial Applicability

[0187] The cotton core for writing instruments of the present embodiment can be preferably applied to cotton cores for writing instruments of a marking type such as underline (registered trademark) pens, oil-based marker pens, and water-based marker pens.

[0188] Description of Reference Numerals

[0189] 10. Writing tool body; 11. Rear pen body; 16. Front pen body; 17. Cotton core (ink absorber); 20. Pen tip; 25. Writing part; 26. Ink guide part; 30. Holding body; 33. Visible part.

Claims

1. A writing tool, characterized in that: The writing tool comprises a cotton core having two or more pore diameter distributions.

2. The writing tool according to claim 1, characterized in that: According to the cross-sectional image analysis, the frequency of the cotton core having a diameter less than 90 μm is high in an area having a radius of 0.5 mm from the center.

3. The writing tool according to claim 1 or 2, characterized in that: The ink composition absorbed in the cotton core is an ink composition containing a fine resin pigment containing a dye.

Images