Notebook

Abstract

To provide a writing instrument that can reliably supply ink to the pen tip and improve ink diffusion. [Solution] A writing instrument A characterized by having a cotton batting 17 having two or more pore size distributions. It is preferable that the frequency of pores less than 90 μm is high in the region with a radius of 0.5 mm from the center, as determined by cross-sectional image analysis of the cotton batting 17.

Description

Technical Field

[0001] The present invention relates to a writing instrument that can reliably supply ink to a pen tip and enhance ink diffusibility.

Background Art

[0002] Conventionally, for the purpose of reliably supplying ink to a pen tip, a filler for a writing instrument with enhanced ink diffusibility, a writing instrument using the same, and the like are known. For example, a reservoir having a rod with a core component having fibers and a surrounding component having fibers, wherein the core component has a first property and the surrounding component has a second property different from the first property. In this reservoir, the first property and the second property are independently selected from the group consisting of fiber bulk density, fiber diameter, fiber material, fiber morphology, fiber surface tension, capillary force, fluid absorption capacity, color, and combinations thereof. Also, in the above reservoir, the fiber bulk density is in the range of about 0.01 g / cm 3 ~ about 0.4 g / cm 3 A reservoir for a non-uniform fiber fluid used in writing instruments such as oil markers and highlighter markers, where the fiber diameter is in the range of about 0.5 μm to about 50 μm, etc. (see, for example, Patent Document 1) is known.

[0003] This reservoir corresponds to a so-called filler for a writing instrument. By making the fiber bulk density of the filler, etc. a "coarse and dense filler", the ink supplied into the filler can diffuse, and ink can be reliably supplied to both pen tips at both ends of the barrel for writing. This coarse and dense filler is characterized by having a part where the fibers are in a dense state at the radial center of the filler and a part where the fibers are in a sparse state at the circumferential part. When the coarse and dense filler is filled with ink, the dense part preferentially sucks up the ink, and the ink diffusibility of the filler is enhanced by quickly supplying the ink to both end faces of the filler.

[0004] Furthermore, other documents provide information on a marking pen (see, for example, Patent Document 2 by the present applicant) characterized by comprising: a barrel; a cotton core housed inside the barrel and comprising a dense portion located near the axis in a cross section perpendicular to the longitudinal direction with relatively low porosity and a sparse portion located around the dense portion with relatively high porosity; an aqueous ink impregnated in the cotton core and having a static surface tension of 35 mN / m or less; and a writing tip connected to the dense portion and guiding the aqueous ink to the tip by capillary force.

[0005] However, while Patent Documents 1 and 2 describe novel writing instrument fillings and writing instruments using them, Patent Document 1 still has issues with efficiently supplying ink to the pen tip, and there is a need to further improve the ink diffusion properties of Patent Documents 1 and 2. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-501226 (Claims, FIG. 1, etc.) [Patent Document 2] Japanese Patent Publication No. 2021-66043 (Claims, Figure 7, etc.) [Overview of the project] [Problems that the invention aims to solve]

[0007] In view of the problems and current state of the above-mentioned prior art, this invention aims to solve them by enabling more efficient ink supply to the pen tip and further improving ink diffusion. The objective is to provide a writing instrument that can do the following. [Means for solving the problem]

[0008] The inventors, after diligently studying to solve the above-mentioned conventional problems, discovered that a writing instrument for the above purpose could be obtained by giving the cotton filling, which is composed of fiber bundles, a specific configuration, and thus completed the present invention.

[0009] In other words, the writing instrument of the present invention is characterized by having a cotton filling with two or more pore size distributions. In the aforementioned batting, it is preferable that the frequency of particles smaller than 90 μm is high in the region with a radius of 0.5 mm from the center, as determined by cross-sectional image analysis. The ink composition absorbed into the aforementioned cotton is preferably an ink composition containing resin fine particle pigments containing dyes. [Effects of the Invention]

[0010] According to the present invention, a writing instrument is provided that can supply ink to the pen tip more efficiently and further enhance ink diffusion. The object and effect of the present invention are recognized and obtained, in particular, by using the components and combinations indicated in the claims. Both the general description above and the detailed description below are illustrative and descriptive, and do not limit the present invention as described in the claims. [Brief explanation of the drawing]

[0011] [Figure 1] These are drawings of a writing instrument illustrating an example of an embodiment of the present invention, where (a) is a front view, (b) is a top view, (c) is a longitudinal section view of the front view, and (d) is a longitudinal section view of (b). [Figure 2] Figure 1 shows the writing instrument with the cap removed, where (a) is a top view, (b) is a front view, (c) is a bottom view, (d) is a longitudinal section of (b), and (e) is a longitudinal section of (c). [Figure 3] Figure 1 is a magnified view of the pen tip side of the writing instrument, where (a) is a front view and (b) is a longitudinal cross-sectional view thereof. [Figure 4](a) is a perspective view of the pen tip of the writing instrument of FIG. 3 as seen from the front side, and (b) is a perspective view of the pen tip as seen from the rear side. [Figure 5] (a) is a front view showing an example of the middle cotton for a writing instrument of the present invention, and (b) is a cross-sectional view taken along the line X-X of the middle cotton in (a), which is a schematic view of a state in which the pore diameter distribution has two or more types of distributions. [Figure 6] These are drawings showing an example of a holding body having a visible portion of the pen tip used for a writing instrument. (a) is a perspective view seen from the front side, (b) is a plan view, (c) is a perspective view seen from the rear side, (d) is a left side view, (e) is a front view, (f) is a right side view, (g) is a perspective view seen from above the front side, (h) is a longitudinal sectional view, (i) is a perspective view seen from above the rear side, and (j) is a bottom view. [Figure 7] These are drawings showing an example of a writing portion attached to the pen tip of FIG. 6. (a) is a plan view, (b) is a perspective view, (c) is a front view, and (d) is a right side view. [Figure 8] These are drawings of the optical microscope cross-sectional observation and the binary image of the image analysis figure of Production Example 1 (Sample A). [Figure 9] These are drawings of the optical microscope cross-sectional observation and the binary image of the image analysis figure of Production Example 2 (Sample B). [Figure 10] This is a pore distribution diagram (the largest inscribed circle in the pore portion) of Production Example 1 (Sample A). [Figure 11] This is a pore distribution diagram (the largest inscribed circle in the pore portion) of Production Example 2 (Sample B). [Figure 12] This is a graph of the pore diameter distribution (the distribution of the largest inscribed circles in the pore portions) of Production Examples 1 and 2 (Samples A and B). [Figure 13] These are graphs showing the relationship between the spatial distribution of pores (distance from the center of the circle and pore area frequency) of Production Examples 1 and 2 (Samples A and B) and drawings explaining the measurement method. [Figure 14] This is a graph showing the pore diameter and area frequency obtained by plotting with threshold values of 50 μm, 90 μm, and 100 μm in the pore distribution (the distribution of the largest inscribed circles in the pore portions) of Production Examples 1 and 2 (Samples A and B). [Figure 15]It is a drawing of the pore distribution (the largest circle inscribed in the pore part) with a threshold value of 100 μm in Production Example 1 (Sample A). [Figure 16] It is a drawing of the pore distribution (the largest circle inscribed in the pore part) with a threshold value of 90 μm in Production Example 1 (Sample A). [Figure 17] It is a drawing of the pore distribution (the largest circle inscribed in the pore part) with a threshold value of 50 μm in Production Example 1 (Sample A). [Figure 18] It is a drawing of the pore distribution (the largest circle inscribed in the pore part) with a threshold value of 100 μm in Production Example 2 (Sample B). [Figure 19] It is a drawing of the pore distribution (the largest circle inscribed in the pore part) with a threshold value of 90 μm in Production Example 2 (Sample B). [Figure 20] It is a drawing of the pore distribution (the largest circle inscribed in the pore part) with a threshold value of 50 μm in Production Example 2 (Sample B). [Figure 21] It is drawings showing the relationship between the distance from the circle center (pore diameter 0 to 100 μm, pore diameter 100 μm or more) and the pore diameter frequency in Production Examples 1 and 2 (Sample A and Sample B), and a drawing showing the measurement method. [Figure 22] It is drawings showing the relationship between the distance from the circle center (pore diameter 0 to 90 μm, pore diameter 90 μm or more) and the pore diameter frequency in Production Examples 1 and 2 (Sample A and Sample B), and a drawing showing the measurement method. [Figure 23] It is drawings showing the relationship between the distance from the circle center (pore diameter 0 to 50 μm, pore diameter 50 μm or more) and the pore diameter frequency in Production Examples 1 and 2 (Sample A and Sample B), and a drawing showing the measurement method. [Figure 24] It is graphs showing the relationship between the distance from the circle center and the pore diameter frequency in Production Examples 1 and 2 (Sample A and Sample B).

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, note that the technical scope of the present invention is not limited to the embodiments detailed below, and extends to the invention described in the claims and its equivalents. In each figure, "front" refers to the direction of the tip of writing instrument A and its components, "rear" refers to the opposite direction, "axial direction" refers to the direction of the axis running from the front to the rear of the writing instrument body (barrel), and "transverse direction" refers to the direction perpendicular to the axial direction. Furthermore, symbols used in common across all drawings represent the same components or members, even if not specifically mentioned in the description of each drawing.

[0013] (First embodiment: overall configuration) Figures 1 to 7 are drawings illustrating a marking pen type writing instrument A according to the first embodiment of the present invention, a cotton wick 17 having two or more pore size distributions, and an example of a pen tip 20 and writing section 25, which are components used in the writing instrument. As shown in Figures 1(a) to 1(d), the writing instrument A of this embodiment is a twin-type writing instrument equipped with a pen tip 20 that guides ink supplied from the writing instrument body (barrel) 10 and has a visible portion that allows the writing direction to be seen, and a rod-shaped polyacetal pen tip 40 on the opposite side of the pen tip 20. Furthermore, a detachable cap 50 protecting the pen tip 20 and a cap 60 protecting the pen tip 40 are attached to both sides of the writing instrument body 10. The cap 50 has a clip portion 51, a friction element 53, and a ventilation hole 54.

[0014] (10 writing instruments, 11 rear shafts) As shown in Figures 1 to 4, the writing instrument body 10 of this embodiment is composed of a rear barrel 11 and a front barrel 16. The rear barrel 11 is a cylindrical body that houses an ink-absorbing body 17 impregnated with writing ink. One end, which is on the right side in the drawings, is a reduced-diameter holding part 13 having a fitting part 12 for fixing a holder 45 that holds a fine-point rod-shaped pen tip 40 by fitting. The large-diameter outer circumference 13a of this holding part 13 is configured to be detachably attached to a cap 60. Furthermore, the other end of the rear shaft 11, which is on the left side, has an opening to which a front shaft 16 is attached by fitting or the like to which a pen tip 20 having a visible portion that allows the writing direction to be seen is fixed. In addition, flat portions 14, 14 are formed on the upper and lower surfaces of the outer circumference on the axially forward side of the rear shaft 11, and as will be described later, when these flat portions 14, 14 are held in the fingers, writing (marking) can be done immediately without changing the grip, that is, they serve as gripping indicator surfaces to make the orientation of the flat-shaped pen tip 20 easier to understand.

[0015] (first axis 16) As shown in Figures 1 to 4, the front shaft 16 is composed of a substantially circular cylindrical body and comprises at least a flange portion 16a towards the rear of the central part, a rear portion 16b having a fitting step portion on the rear side of the flange portion 16a, a front portion 16c having a fitting step portion on the front side, an inclined opening 16d at the tip of the front portion 16c, and within the inclined opening 16d, a projection (not shown) for ensuring that the ink guide portion 26 is directed towards the center of the cotton 17 which serves as the ink absorbent, and an annular contact portion (not shown) for contacting the rear end of the holder 30. Reference numeral 16a1 indicates an inclined surface portion on the rear end surface of the flange portion 16a that slightly corresponds to the plane 14 of the rear shaft 11 for alignment with the rear shaft 11. The writing instrument body 10, composed of the front barrel 16 and the rear barrel 11, is formed from a thermoplastic resin, thermosetting resin, etc. For example, it is molded into the above configuration using a resin such as polypropylene and functions as the writing instrument body (barrel). The writing instrument body 10 is molded to be opaque or transparent (and semi-transparent), and either can be adopted from the viewpoint of appearance and practicality.

[0016] (17g padding) The padding 17 serves as an ink-absorbing material and is impregnated with ink compositions for writing instruments, such as water-based ink, oil-based ink, and thermochromic ink. In this invention, the padding is composed of two or more types of pore size distributions. Figure 4(a) is a front view showing an example of the padding 17, and (b) is a longitudinal cross-sectional view of the padding 17 of (a), which is a schematic diagram of a state in which the pore size distribution has two or more types. This padding 17 is padding having two or more types of pore size distributions, and has an outer sheath 17a made of a resin film on its outer circumference, with 17b being the first pore size portion, and the outer circumference of the first pore size portion 17b being the second pore size portion 17c. The presence or absence of two or more types of pore size distributions in this padding 17 can be verified, for example, by (1) checking if the pore distribution is different according to a mercury porosimeter, (2) checking if the distribution of inscribed circle diameters is different according to cross-sectional image analysis, or (3) checking if the distribution of equivalent pore diameters is different according to cross-sectional image analysis.

[0017] Measurement using a mercury porosimometer can be confirmed by measuring the pores within the cotton and determining the differences in their distribution. While ordinary batting without pore size distribution has a pore distribution of approximately one peak, batting with two or more types A batting with a pore size distribution can be considered to have two peaks, that is, a pore distribution with two peaks. This two-peak pore distribution means that within the pores of the batting, there are fine and coarse parts. This merely describes the distribution of the pore state, and does not apply to conventional batting. This is different from the concept of having both low and high density. The conventional low and high states refer to differences in the volume ratio (or cross-sectional area ratio) between pores and fibers. On the other hand, the capillary force generated by the cotton batting and ink is determined by the fineness and coarseness of the pores. To improve ink diffusion, it is necessary to create areas with low and high capillary force within the cotton batting, and this is achieved (essentially, not by density) by the coarseness and fineness of the pores.

[0018] Using a mercury porosimeter, the presence or absence of a pore size distribution in the padding can be determined by calculating the number of peaks in the pore distribution shown below. In a mercury porosimeter, the number of peaks in the pore distribution is determined by impregnating a cotton batting with mercury and then calculating the distribution of equivalent pore diameters from the pressure and impregnation volume. The resulting graph of equivalent pore diameters and their frequencies is then subjected to peak separation. While peak separation is a common method, in this study, we used the peak separation method developed by the Japan Energy Society. Based on the above analysis, the pore size distribution of the cotton is separated by peaks. The separated peak positions are displayed on a logarithmic scale, so they are converted back to their original values. From these results, the distance between peaks is calculated, half of the full width at half maximum (FWHM) of the component peaks is found, and their sum is calculated. If the distance between peaks is smaller than the sum of the half peak widths, and therefore the two peaks cannot be observed separately, then there is no pore distribution. In contrast, for cotton with two or more pore size distributions, by calculating the number of pore distribution peaks in the same way as above, that is, by using the results of peak separation, it can be confirmed from the relationship between the distance between component peaks and the line widths that the cotton has two peaks, i.e., two pore size distributions.

[0019] Furthermore, by measuring the distribution of inscribed circle diameters through cross-sectional image analysis, it is possible to determine whether or not there is a pore size distribution in the padding. By analyzing the cross-section of the batting using image analysis, it is possible to determine the presence or absence of pore size distribution. Specifically, by observing the cross-section of the batting and analyzing its image, the pore size (diameter distribution of the inscribed circle) can be determined. The measurement method involved injecting a curable resin (en-thiol resin-based photocurable adhesive: manufactured by Nichika Co., Ltd.) into the obtained batting and allowing it to harden. Next, the batting was cut perpendicular to the axis, the cross-section was polished, and the cross-section was observed and photographed using an optical microscope (Keyence VHX-8000). Image analysis (material development comprehensive package software GeoDict by Math2Market) was used to separate the fibrous portion from the void portion (impregnated resin portion). By determining the maximum circular distribution inscribed within the void portion, it was considered that a characteristic feature appeared at a void diameter of 90 μm. In cotton with a pore size distribution, the frequency of pores smaller than 90 μm is high. When the frequency distribution is analyzed by dividing it into pores with an inscribed circle diameter of less than 90 μm and those with an inscribed circle diameter of 90 μm or more, the frequency of pores smaller than 90 μm is higher in the sample (dense area) in the region with a radius of 0.5 mm from the center, while the frequency of pores larger than 90 μm is lower in the sample in the same region with a radius of 0.5 mm from the center. From the above analysis, it was found that in cotton with a pore size distribution, if the frequency of pores smaller than 90 μm is high, then there is a distribution in the pore size. It is preferable that the frequency of pores smaller than 90 μm is high in the region with a radius of 0.5 mm from the center, and in cotton with a pore size distribution, the frequency of pores smaller than 90 μm (fine parts) is high in the radial center, but the location of these fine parts can also be in the circumferential area. In summary, it was found that if there is a difference in the diameter distribution of the inscribed circle of pores within the cotton in a certain region, then the cotton has a pore size distribution.

[0020] Furthermore, by measuring the distribution of equivalent pore diameters through cross-sectional image analysis, it is possible to verify the presence of two or more types of pore diameter distributions in the filling material. The cross-section of the batting was observed, and the distribution of the equivalent diameter of the pores was determined from the image analysis. By increasing the resolution of the cross-sectional image from the above measurement method, the fiber circumference (l) and the area (s) of the space within a certain space (e.g., a 1x1mm square area) were determined. Although the pores are not circular but irregular in shape, their circumference and area allow us to determine the diameter (2r: equivalent diameter) if they were considered to be circular, using the following formula. Circumference / Area = 2πr / πr 2 =2 / r =l / s=fiber circumference / area of ​​space When the equivalent diameter of pores in the above microscopic region is determined, the equivalent diameter is small in the "fine" (dense) region and large in the "sparse" (coarse) region. Capillary force is expressed as l / s × γ (surface tension) × cosθ (contact angle) and is determined by the circumference and area of ​​the pore. In the "fine" (dense) region of the batting, the equivalent diameter is small, and in the "sparse" (coarse) region, it is large. It was found that if there is a difference in the diameter distribution of the inscribed circles of pores in a certain region, the batting has a pore diameter distribution. This analysis is essential from the perspective of the capillary force distribution within the batting. By any of the above methods (1) to (3), it is possible to verify that the batting has two or more pore size distributions. Preferably, due to factors such as ease of operation, measurement accuracy, and measurement effort (the above (2) requires fewer observation images than (3), and sids are not lost even with low resolution), it is desirable to measure the presence or absence of pore size distribution in the cotton by measuring the distribution of inscribed circle diameters by image analysis of the cross-section as described in (2) above.

[0021] To obtain a batting with two or more pore size distributions, for example, it can be produced by using fibers with different fiber bulk density, fiber diameter, fiber material, fiber morphology, fiber surface tension, and capillary force, or by suitably combining two or more of these. Examples of fibers that can be used include natural fibers, animal hair fibers, polyacetal resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl resins, polycarbonate resins, polyether resins, and polyphenylene resins, one or more of these in combination.

[0022] Specifically, it can be manufactured as follows, for example. After convergence, a bundle of threads with a second pore size distribution was inserted into the center of a bundle of threads with a first pore size distribution. A polypropylene cylinder with a length of 80 mm and an inner diameter of 6 mm was used as the barrel, and the fillings from each of the examples and comparative examples described below were filled into it and subjected to the following experiments. The thread bundles were made by compressing and bundling polyester fibers, and weighing them to achieve a predetermined density ratio. By filling the polypropylene cylinder, it is possible to obtain writing instrument fillings with the above-described pore size distribution characteristics, which include two or more pore size distributions.

[0023] (Ink for writing instruments) The composition of the ink used for writing instruments is not particularly limited, and a suitable formulation such as water-based ink, oil-based ink, or thermochromic ink can be used depending on the intended use of the writing instrument. For example, in the case of an underline pen, the ink can contain fluorescent dyes, such as Basic Violet 11, Basic Yellow 40, or thermochromic microcapsule pigments. Preferably, a resin fine particle pigment ink composition containing a dye is desired. Examples of dye-containing resin microparticle pigment inks include a dispersion of colored resin microparticles in which the colored resin microparticles are dispersed in water, wherein the colored resin microparticles are composed of at least (meth) cyclohexyl acrylate monomer and a basic dye or an oil-soluble dye, the content of the (meth) cyclohexyl acrylate monomer is 30% by mass or more relative to the total polymer components constituting the colored resin microparticles, and the content of the basic dye or oil-soluble dye is 15% by mass or more relative to the total polymer components, a water-soluble organic solvent, and water. Furthermore, by adjusting the types and amounts of ink components in these ink compositions, the ink viscosity (25°C: complate-type viscometer) can be set to 1-5 mPa·s and the surface tension to 30-60 mN / m. Moreover, in combination with the characteristics of the writing instrument cotton of the present invention, the amount of ink flowing from the pen tip 20 and pen tip 40 of the marking pen type writing instrument can be easily set to a desirable range, in this embodiment, 5-20 mg / m.

[0024] Furthermore, when using an ink composition containing thermochromic microcapsule pigments, for example, as shown in Figure As shown in 2(c) and (d), a cylindrical friction body 53 made of thermoplastic elastomer with an erasing ability (erasing rate) of less than 70% as specified in JIS S 6050-2002 can be fixed to the recess 52 of the cap 50. The friction body 53 generates frictional heat easily through its frictional action and has low wear, thereby reducing the generation of eraser residue during friction and preventing contamination of the surrounding area. The ventilation holes 54 are for facilitating the attachment and removal of the friction body 53.

[0025] (Pen nib 20) As shown in Figures 2 to 7, the pen tip 20 has at least a writing section 25, an ink guide section 26 that guides ink from the writing instrument body 10 to the writing section 25, and a holder 30 having a visible section. The writing section 25 and the ink guide section 26 are attached to the holder 30 by adhesive, welding, fitting, or the like. The writing section 25 has a slanted (knife-cut) shape on the upper side of the rectangular base so that it is angled for easy writing. The angle of this writing section 25 can be set as appropriate according to the ease of use for writing, etc. Furthermore, as shown in Figures 7(a) to (d), the writing section 25 has a writing section 25a with a larger line width W1 and a writing section 25b with a smaller line width W2, so that the line width can be adjusted (selected) between W1 and W2 by tilting the shaft. In this embodiment, the ratio of W1:W2 is 2 or more:1. The line width W1 is 2.0 to 5.0 mm, and the line width W2 is 1.0 to 2.5 mm.

[0026] The writing section 25 can be made of, for example, a porous material with pores, specifically a sponge, sintered body, fiber bundle, foam, sea sponge, felt, or porous material. Materials used to form these porous materials include, for example, natural fibers, animal hair fibers, polyacetal resins, polyethylene resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl resins, polycarbonate resins, polyether resins, and polyphenylene resins. In this embodiment, the writing section 25 is made from a sintered core formed by sintering plastic powder (e.g., PE) to further improve the writing feel.

[0027] The ink guide section 26 is in the shape of a thin plate and has an inclined portion 26a on the rear side. It is preferable that its cross-section be rectangular or elliptical in shape in order to maximize the area of ​​the visible portion. In this embodiment, the cross-section is rectangular. The ink guide section 26 is not particularly limited as long as it efficiently guides (supplies) the ink from the ink absorber 17 absorbed within the writing instrument body 10 to the writing section 25 via the ink guide section 26. Examples include fabrics such as nonwoven fabrics, woven or knitted fabrics, fiber bundles, or permeable materials such as permeable foams or sintered bodies. The writing section 25 and the ink guide section 26 can be integrally constructed from a single material, but preferably, in order to further demonstrate the effects of the present invention, to efficiently supply ink, and to further improve the writing feel at the writing section, it is desirable to connect or join them as separate components, or to connect or join them via a holder as described later. In this embodiment, "nonwoven fabric" refers to a fabric-like structure formed by not knitting or weaving a mass of one or more fibers. The fiber material can be synthetic fibers, natural fibers, animal hair fibers, inorganic fibers, etc. Examples of synthetic fiber materials include one or more combinations of polyacetal resins, polyethylene resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl resins, polycarbonate resins, polyether resins, and polyphenylene resins.

[0028] The fibers that make up the fabric are produced by methods such as melt spinning, dry spinning, wet spinning, direct spinning (meltblown, spunbond, electrostatic spinning, etc.), extracting fine fibers by adsorbing one or more resin components from composite fibers, and beating the fibers to separate them. It can be obtained by well-known methods, such as those used to acquire it. Furthermore, the fibers that make up the fabric may consist of one or more types of resin components, and composite fibers, such as core-sheath type, sea-island type, side-by-side type, and orange type, which are generally referred to as composite fibers, can be used.

[0029] The fineness of the fibers constituting the fabric is not particularly limited, but it is preferably 0.1 to 500 dtex (decitex), and more preferably 2 to 5 dtex (decitex). The fiber length is also not particularly limited, but short fibers, long fibers, or continuous fibers can be used. If the fabric is woven or knitted, it can be prepared by weaving or knitting the fibers prepared as described above.

[0030] When the fabric is a nonwoven fabric, methods such as a dry method or a wet method can be used to prepare a fiber web capable of producing a nonwoven fabric. Methods for entangling and / or integrating the fibers constituting the fiber web to form a nonwoven fabric include, for example, entangling by needles or water flow, integrating the fibers with a binder, or, if the fiber web contains a thermoplastic resin, melting the thermoplastic resin by heat treatment of the fiber web to integrate the fibers. Methods for heat treatment of the fiber web include, for example, heating and pressurizing with a calender roll, heating with a hot air dryer, or melting the thermoplastic resin fibers by irradiating with infrared rays under no pressure. Alternatively, the nonwoven fabric may be prepared by collecting fibers spun using a direct spinning method. Examples of fiber bundle cores include parallel fiber bundles made from the above-mentioned fiber materials (synthetic fibers, natural fibers, ..., a combination of one or more types of polyphenylene resins, etc.) that have been processed, or fiber bundles that have been resin-processed. In the case of permeable foams, they can be prepared by known methods, such as pouring molten resin into a mold for molding and foaming. Sintered bodies can be composed of porous bodies (sintered cores) obtained by sintering plastic powders such as polyacetal resins, polyethylene resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl resins, polycarbonate resins, polyether resins, and polyphenylene resins.

[0031] The shape and thickness of the ink guide section 26 are determined based on the mounting method to the holder 30, the shape of the writing section 25, maximizing the visible area of ​​the visible section, and efficiently supplying ink to the writing section 25. Preferably, the width and length are approximately the width and length of the mounting surface of the holder 30, which will be described later, to which the thin plate-shaped ink guide section 26 is fixed, and suitable lengths are set to efficiently supply ink to the writing section 25. Furthermore, the thickness (width when viewed from the direction perpendicular to the visible surface) t of the thin plate-shaped ink guide section 26 is preferably less than 1.5 mm, more preferably 1.2 mm or less, and particularly preferably 0.8 mm or less, from the point of maximizing the visible area of ​​the visible section, and the lower limit is preferably 0.5 mm or more from the point of supplying a suitable amount of ink and productivity. In this embodiment, the ink guide section 26 is composed of a fiber bundle core made of PET with a rectangular cross-section, which allows for efficient ink flow with a small cross-sectional area. Its longitudinal length is 20 mm, its width is 2 mm, and its thickness t is 0.8 mm. The rear end 26a of this ink guide portion 26 is inserted into the front end of the ink storage body 17. The tip end 26b is in contact with the writing section 25 via the holder 30. This configuration ensures that the ink in the ink storage body 17 is efficiently supplied to the writing section 25 in the appropriate amount via the ink guide section 26 by capillary action.

[0032] (Holding body 30) As shown in Figures 2 to 7, the holder 30 fixes the writing section 25 and the ink guide section 26, with its rear end fixed inside the inclined opening 16d of the front shaft 16 of the writing instrument body 10. The holder has a bulging main body section 31, a flange section 32 on the front side of the main body section 31 that contacts the end face of the writing instrument body 10, and a visible section 33 that allows the writing direction to be seen. The visible section 33 has front holding sections 34a and 34b that hold the front end (end face) of the writing section 25, and retaining sections 34c and 34d provided at one end of each holding section that receive the end face of the writing section 25. Furthermore, the main body 31 is provided with a rear holding portion 35 connected to the main body 31 on its rear bottom surface. To maximize the viewing area of ​​the visible portion 33, the entire bottom surface of the holder 30 composed of these components has a structure attached (placed) on the bottom surface of the holder 30. Specifically, a concave holding groove 36 is formed on the entire bottom surface of the holder 30 in the longitudinal direction, which fits and holds the thin plate-shaped (rectangular cross-section) ink guide portion 26. In addition, a concave fitting portion 31a is formed on the outer peripheral surface of the main body 31 in the width direction.

[0033] Furthermore, on both sides of the concave retaining groove 36 to which the writing section 25 is fixed and the concave retaining groove 36 to which the ink guide section 26 is fixed, ribs 37, 37…, 38, 38… are formed at predetermined intervals perpendicular to the axis on the surface that contacts the writing section 25 and the ink guide section 26. This allows the fragile feet of the writing section 25 and the ink guide section 26, which may have dimensional variations due to the molding process, to be stably assembled to the retainer 30. In this embodiment, the widthwise length of the mounting surface 36a of the retaining groove 36 is set to be slightly shorter than the widthwise length of the tip side 26b of the ink guide section 26. This increases the fixing force by pressing the tip side 26b of the ink guide section 26 against the retaining groove 36a and securing it, thereby ensuring a secure connection with the writing section 25. A thin, plate-shaped ink guide portion 26 is fixed to the mounting surfaces 36a and 36b of the retaining groove 36 of the holder 30 by adhesive bonding, welding, etc., and is fixed to the writing portion 25. In this writing instrument A, the writing portion 25 is fixed (attached) to the holder 40 by fitting and holding the writing portion 25 between the front holding portions 44a and 44b. Furthermore, in order to ensure that the writing portion 25 is fixed (prevents it from coming off), adhesive bonding, welding, etc., may be used. Furthermore, air circulation grooves 39, 39 are formed on the longitudinal outer surface of the main body 31, and even if the air pressure inside the writing instrument expands, the air circulation grooves 39, 39 can adjust it, thus eliminating ink leakage and other problems.

[0034] The ink guiding section 26 is composed of a fiber bundle core with a rectangular or elliptical cross-section, and in this embodiment, a fiber bundle core with a rectangular cross-section. The writing section 25 is composed of a resin sintered body. The writing section 25 and the ink guiding section 26 are fixed to the retaining groove 36 and mounting surfaces 36a and 36b of the holder 30, and the ink guiding section 26 and the writing section 25 are pressed together and fixed in place. As a result, ink from the ink storage body 17 is supplied smoothly to the writing section 25 via the ink guiding section 26.

[0035] The entire holder 30, as constructed in this manner, is made of a hard material, such as a hard material that is visible, such as glass or a resin that does not have rubber elasticity. As a resin that does not have rubber elasticity and is visible, for example, by molding it from a material with 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 nylon 6 and nylon 12), acrylic, polymethylpentene, polystyrene, or ABS, the characters written in the writing direction can be effectively seen in the visible part 33. Alternatively, only the visible part 33 may be made of a material that is visible. The visible light transmittance can be determined by measuring the reflectance with a multi-light source spectrophotometer [Suga Test Instruments Co., Ltd., (MSC-5N)]. Furthermore, the retainer 30 may be made of one of the above materials, or in a manner that further improves durability and visibility. For these reasons, it may be constructed using two or more types of materials and can be molded using various molding methods such as injection molding and blow molding.

[0036] In this embodiment, as shown in Figure 4(b), the visible portion 33 of the holder 30 has a minimum width S in the width direction of 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 of the visible portion 33 of the holder 30 expands from the front end to the rear end, and the minimum width S is the length in the width direction of the visible portion 33 at the front end of the holder 30, and its width (parallel to the pen tip) is 3.7 mm or more. In this embodiment, the maximum width of the visible portion 33 in the width direction is 4.5 mm. By setting this minimum width S to 3.7 mm or more, the configuration ensures that 10.5-point (No. 5 type) printed on the document can be clearly seen in the visible area 33. In Japan, No. 5 type is commonly used as the standard for general official documents. Furthermore, the length Y of the visible portion 33 is twice the minimum width S, i.e., 7.4 mm or more. For example, at a writing angle of 60°, even when viewed from above, the 3.7 mm width is visible. The characters are positioned within the visible area 33 (3.7mm / cos60°=7.4mm). In order to set the minimum width S of the visible portion 33 to 3.7 mm or more and its length Y to 7.4 mm or more, the structure, shape, etc. of each component of the pen tip 20 (writing portion 25, ink guidance portion 26, holder 30) can be configured (specified) as described above and combined in a suitable manner.

[0037] Furthermore, in this embodiment, the width (length when viewed from the vertical direction of the visible portion 33 surface) t of the ink guidance portion 26 is less than 1.5 mm, more preferably 1.2 mm or less, and particularly preferably 0.8 mm or less, in order to ensure a sufficient ink flow to the writing portion 25 and to further increase the visible portion 33 area. Furthermore, the ink guide section 26 is fitted and held in the concave retaining groove 36 and mounting surfaces 36a and 36b. It is fixed in place by being attached in the same way, and moreover, for the sake of efficient assembly and productivity, its side is not a structure that covers the entire ink guide section 26, but is open to the outside air. Therefore, the overall width and length including the width t of the ink guide section 26 is kept to the minimum necessary, and the width S of the visible section 33 is maximized.

[0038] Furthermore, as shown in Figure 3(b), by having one ink guide section 26 on one side of the visible section 33, that is, by positioning the ink guide section 26 on the near side during writing (the side where the pen tip 20 is at an obtuse angle to the ink guide section 26), the visible section 33 remains clearly visible regardless of the direction of writing, even when a natural writing angle is used. If the ink guide section 26 were positioned on the far side (upper side) instead of the near side during writing, the mechanism of operation of the visible section 33 would be different, as it would cross the direction of writing (marking) and partially obscure the characters.

[0039] Next, the pen tip 50 for fine writing is a fine-point rod-shaped pen tip, as shown in Figures 1(a) and (b), with a circular cross-section. The rear end (ink reservoir side) of the pen tip 40 is inserted into the ink reservoir 17, and ink from the ink reservoir 17 is supplied to the pen tip 40 by capillary action. This pen tip 50 is made of a porous material, for example, a parallel fiber bundle made of one or more types of materials such as natural fibers, animal hair fibers, polyacetal resin, polyethylene resin, acrylic resin, polyester resin, polyamide resin, polyurethane resin, polyolefin resin, polyvinyl resin, polycarbonate resin, polyether resin, and polyphenylene resin, processed fiber bundles such as felt, or a fiber core made by resin processing these fiber bundles, or plastic powder such as thermoplastic resins such as polyolefin resin, acrylic resin, polyester resin, polyamide resin, and polyurethane resin. It consists of a porous body (sintered core) made by sintering the end of a substance, etc. Preferred pen tip 40 includes fiber bundle cores, fiber cores, sintered cores, felt cores, sponge cores, and inorganic porous cores, with fiber cores being particularly preferred in terms of deformability and productivity. The porosity, size, and hardness of the pen tip 50 used will vary depending on the type of ink, the type of writing instrument, etc., and for example, a porosity of 30-60% is preferred. In the present invention, the "porosity" of the writing core is calculated as follows. First, a writing core with a known mass and apparent volume is immersed in water and allowed to soak up the water completely, and then its mass is measured after it is removed from the water. From the measured mass, the volume of water soaked into the writing core is derived. Assuming that this volume of water is the same as the pore volume of the writing core, the porosity is calculated from the following formula. Porosity (unit: %) = (volume of water) / (apparent volume of pen tip 50) × 100

[0040] In the writing instrument A configured in this way, the writing instrument wick of the present invention, which contains writing ink within the writing instrument body 10, has the following characteristics: the wick Z has two or more types of pore size distributions, the first pore size is 50-300 μm, and the second pore size is 50-90% of the first pore size. By inserting and holding the tip shaft 16, the pen tip 20 (writing section 25, ink guide 26, holder 30) with the above configuration is sequentially fitted and fixed to the front end, and the holder 45 to which the pen tip 40 is fixed is fitted and fixed to the other end, a twin-type writing instrument A can be easily manufactured. The ink absorbed into the writing instrument cotton Z' of the present invention can be efficiently supplied by capillary force to the writing section 25 and the pen tip 40 at the pen tip 20 via the thin plate-shaped ink guide section 26, thereby further enhancing ink diffusion. A writing instrument cotton and a writing instrument using the same can be obtained.

[0041] In this writing instrument A, the pen tip 40 is the same as that of conventional general-purpose pen tips, so the function of the pen tip 20 will be explained below. As shown in Figures 2 to 7, the pen tip 20 of this writing instrument A has a visible portion (window portion) 33 that allows the writing direction to be seen. The ink of the writing instrument's cotton wick Z' reaches the writing section 25 and the pen tip 40 respectively by the capillary force of the cotton wick Z', and is used for writing. When writing, looking at the visible portion (window portion) 33 makes it easier to align the starting position of the stroke and to stop precisely at the desired end point, preventing over-strokes and smudging.

[0042] The pen tip in the above embodiment comprises at least a writing section 25 that allows selection of two line widths, a holder 30 having a visible section 33, and an ink guide section 26 that guides ink from the writing instrument body 10 to the writing section. By configuring the minimum width (S) of the visible section 33 to be 3.7 mm or more and the length (Y) of the visible section 33 to be 7.4 mm or more (hereinafter referred to as "Configuration 1"), or by configuring the ink guide section 26 to be on the side facing the user during writing, that is, by arranging the ink guide section 26 on the side facing the user during writing (the side where the pen tip 20 is at an obtuse angle to the ink guide section 26) when it is fixed to the holder 30 (hereinafter referred to as "Configuration 2"), it is possible to achieve a high degree of balance between maximizing the effective area of ​​the visible section 33 that allows the user to see the writing direction, ease of viewing, and ease of writing.

[0043] In the above configuration 2, even when a natural writing angle is used, the visibility of the visible area 33 is further improved regardless of the direction of writing, as the ink guide section 26 directs the writing. If the ink guide section 26 is positioned on the back (upper) side instead of the front side during writing, or if two ink guide sections are positioned on both sides of the writing area in a U-shape, the mechanism of operation of the visible area 33 differs in that it crosses the direction of writing (marking) and partially obscures the writing. In this configuration as well, it is possible to achieve a high degree of balance between maximizing the effective area of ​​the visible area 33, visibility, and ease of writing. The wider visible area 33 makes the writing direction even clearer, further improving the ease of writing.

[0044] By configuring the ink guide section 26 to have a width t of 1.2 mm or less when viewed from the vertical surface of the visible section 33 (hereinafter referred to as "configuration 3"), the area of ​​the visible section can be further maximized, and the effects of the present invention can be achieved to an even higher degree. Furthermore, by configuring the ink guiding section 26 to have a rectangular or elliptical fiber bundle core in cross-section, and the writing section 25 to be made of a resin sintered body, and by fixing the ink guiding section 26 and the writing section 25 to the holder 30, and by configuring the ink guiding section 26 and the end of the writing section 25 to be in contact (hereinafter referred to as "configuration 4"), the ink guiding section 26 can efficiently flow (supply) ink to the writing section 25 with a small cross-sectional area, resulting in a good writing feel and further enhancing the effects of the present invention. Furthermore, this writing instrument A has a distribution of two or more pore sizes, with the first pore size being 50-300 μm and the second pore size being 50-90% of the first pore size. Because of the excellent ink flow provided by the writing instrument cotton Z' of the present invention, even when writing at a high speed with the pen tip 20 (or pen tip 40), the ink supply keeps up well, resulting in a writing instrument that does not produce smudging or other issues in the writing.

[0045] The writing instrument of this embodiment is not limited to the above-described forms and can be further modified in various ways. For example, the writing instrument core of the above-described form may be equipped with a fiber bundle core without a window, or it may be filled with oil-based ink. Furthermore, instead of a marking pen tip, it may be equipped with a ballpoint pen tip.

[0046] In the writing instruments of the above embodiment, each writing instrument is composed of either configuration 1 or configuration 2, but configurations combining configurations 1 and 2, and configurations 1 or 2 with configuration 3 and / or configuration 4 are also possible. Each writing instrument may be constructed by combining these elements. Furthermore, in the above embodiment, the writing instrument of configuration 1 is configured such that the ink guide section 26 is on one side of the visible section 33 as a preferred configuration. However, even in the configuration of configuration 1, the effects of the present invention can be demonstrated in a configuration in which there are two ink guide sections 26 on the upper and lower surfaces of the visible section 33 (even if there are two ink guide sections 26, 26 on both sides of the writing section 25, which are integral or separate components and form a U-shape, the ink guide section may cross the characters in the direction of writing (marking). However, the effects of the present invention can also be demonstrated in a configuration of the visible section 33 with an unprecedentedly wide range, that is, a configuration in which the minimum width (S) of the visible section 33 is 3.7 mm or more and its length (Y) is 7.4 mm or more). Furthermore, in addition to fixing the holder 30 to the writing section 25 and ink guide section 26 by fitting them to the holder 30, the fixing method can also be performed by fixing with a hot melt adhesive, fixing by solvent penetration, fixing by ultrasonic welding, fixing with a reactive adhesive (moisture curing, UV curing, oxygen curing, two-component curing), fixing with a solvent-based adhesive (soluble synthetic resin, emulsion, rubber), fixing with tape, or fixing with double-sided tape. The porosity of the writing section 25 is preferably within the following range. The porosity is preferably 30-80%, and more preferably 40-70%.

[0047] Furthermore, although the writing instrument A of the present invention is shown as a twin-type writing instrument, the pen tip 40 may be omitted (the barrel body may be a bottomed cylindrical barrel body) and a single-type writing instrument equipped with a pen tip 20 may be used, or the writing instrument may have a mechanism that extends and retracts the pen tip 20 by clicking. In the writing instrument A of the above embodiments, the cross-section of the shaft of the writing instrument body is formed as a circular shaft, but it may also be made into an irregular shape such as a triangular shape, a square or more rectangular shape, or an elliptical shape. Furthermore, although the case in which the entire pen tip 20 is made of a transparent material is shown, the pen tip 20 may also be made by using a two-color molded product of a resin material other than a transparent material, in which at least the visible part 33 is made of a transparent material, and the body part 31 that is attached inside the writing instrument body is made of a resin material other than a transparent material. Furthermore, although the above embodiments were described using inks for writing instruments (water-based inks, oil-based inks, and thermochromic inks), liquid substances such as liquid cosmetics, liquid pharmaceuticals, coating solutions, and correction fluids may also be used. [Examples]

[0048] Next, the present invention will be described in more detail with reference to manufacturing examples, embodiments, and comparative examples, but is not limited to the manufacturing examples described below.

[0049] [Manufacturing Example 1: Manufacturing of Padding (Sample) A] For the filling A, 650 strands of 5d (denier, the same applies hereafter) and 460 strands of 3d, manufactured by Toray Industries, were used. After convergence, a bundle of yarn with a second differential pore size distribution was inserted into the center of a bundle of yarn with a first pore size distribution. A polypropylene cylinder with a length of 80 mm and an inner diameter of 6 mm was used as the core, and the fillings for each of the examples and comparative examples described below were filled into it and subjected to the following experiments. The yarn bundles were made by compressing and bundling polyester fibers, and weighing them to achieve a predetermined density ratio. Filling the polypropylene cylinder produced filling A with two types of pore size distributions: a first porosity, a second porosity, and a ratio of their porosity. For padding B, 15,300 strands of 3-denier Toray Industries were bundled together, and a polypropylene cylinder with a length of 80 mm and an inner diameter of 6 mm was used as a casing for the following experiment. The yarn bundles were made by compressing and bundling polyester fibers, and their weight was measured to achieve a predetermined density ratio. By filling the polypropylene cylinder with these bundles, padding B with a pore size distribution that resulted in a first porosity was produced.

[0050] The presence or absence of pore size distribution was verified for the padding (samples) A ​​and B obtained in the above manufacturing examples 1 and 2 using the measurement method described below.

[0051] [Measurement method: Measurement of the distribution of the inscribed circle diameter by image analysis of the cross-section] The pore distribution was measured based on the results of optical microscope observations of the cotton padding (samples) A ​​and B used as test specimens. The equipment and measurement conditions used are as follows. Equipment name: Materials development integrated package software, GeoDict, manufactured by Math2Market, Nissan Arc Development Program (applicable to Figure 13) Measurement item: Diameter of the largest inscribed circle relative to the void Measurement conditions: Optical microscope images were input into an image analysis system and binarized to separate fibers from pores. Then, the diameter of the largest inscribed circle was measured for each pore. Due to the limited number of data points, a moving average was used to determine the pore diameter distribution.

[0052] The cross-section of padding A was analyzed using image analysis to determine the presence or absence of pore size distribution. Specifically, the cross-section of padding A was observed, and the pore size (diameter distribution of the inscribed circle) was determined from the image analysis. The measurement method involved injecting a curable resin (en-thiol resin-based photochemical adhesive: manufactured by Nichika Co., Ltd.) into the obtained batting A and B and allowing it to harden. Next, the batting was cut perpendicular to the axis, the cross-section was polished, and the cross-section was observed and photographed using an optical microscope (Keyence VHX-8000). This was then analyzed using image analysis (material development comprehensive package software Math2Market GeoDic) to identify the fibrous parts and void parts (impregnated resin). The fatty portion and the surrounding tissue were decomposed. The largest circular distribution inscribed within the pore area was determined for both samples A and B, yielding the results shown in Figures 8 to 24.

[0053] Figures 8 and 9 show optical microscope cross-sectional observations and binarized images of the cotton padding for manufacturing examples 1 and 2 (samples A and B), respectively. Figures 10 and 11 show the pore distribution diagrams (largest circle inscribed in the pore area) for manufacturing examples 1 and 2 (samples A and B). The optical microscope cross-sectional observation diagram in Figure 10 is shown in black and white, but the original optical microscope cross-section is shown in four colors: green, yellow, white, and red. In Figure 10, "yellow" represents a circular gray area, "white" represents a white dot, "red" represents a black dot, and "green" represents areas other than those described above as "yellow, white, and red." Similarly, in the following examples 12 to 20, the diagrams are shown in black and white, but the original optical microscope cross-section is shown in four colors: green, yellow, white, and red. Next, Figure 12 is a graph of the pore size distribution (distribution of the largest circle inscribed in the pore area) for manufacturing examples 1 and 2 (samples A and B), Figure 13 is a graph showing the relationship between the spatial distribution of pores (distance from the center of the circle and pore area frequency) for manufacturing examples 1 and 2 (samples A and B), and a diagram explaining the measurement method, Figure 14 is a graph showing the pore diameter and area frequency for manufacturing examples 1 and 2 (samples A and B) with thresholds of 50 μm, 90 μm, and 100 μm, and Figures 15 to 20 are diagrams of the pore distribution (largest circle inscribed in the pore area) for manufacturing examples 1 and 2 (samples A and B) with thresholds of 100 μm, 90 μm, and 50 μm, and Figure 21 is a manufacturing Figure 21 shows the relationship between the distance from the center of the circle (pore diameter 0-100 μm, pore diameter 100 μm or more) and the pore diameter frequency for Examples 1 and 2 (Samples A and B), along with diagrams illustrating the measurement methods. Figure 23 shows the relationship between the distance from the center of the circle (pore diameter 0-90 μm, pore diameter 90 μm or more) and the pore diameter frequency for Manufacturing Examples 1 and 2 (Samples A and B), along with diagrams illustrating the measurement methods. Figure 24 shows the relationship between the distance from the center of the circle (pore diameter 0-50 μm, pore diameter 50 μm or more) and the pore diameter frequency for Manufacturing Examples 1 and 2 (Samples A and B), along with diagrams illustrating the measurement methods.

[0054] A comprehensive evaluation of the results in Figures 8 to 24 reveals that the characteristics of the batting (Samples A and B) in Manufacturing Examples 1 and 2 are distinct, with a pore diameter of 90 μm as the dividing line. Specifically, comparing the results in Figures 12 to 14 and Figures 21 to 24, Manufacturing Example 2's batting (Sample B) has a higher frequency of pores smaller than 90 μm. Analyzing the frequency distribution by dividing the pores into those with an inscribed circle diameter of less than 90 μm and those with a diameter of 90 μm or more, the frequency of pores smaller than 90 μm is higher in Manufacturing Example 1's batting (Sample A) in the region with a radius of 0.5 mm from the center (a denser area), while the frequency of pores with a diameter of 90 μm or more is lower in Manufacturing Example 1's Sample A in the region with a radius of 0.5 mm from the center. From the above analysis, it was found that Manufacturing Example 1's batting (Sample A) has a distribution in its pore diameter, while Manufacturing Example 2's batting (Sample B) does not have a distribution in its pore diameter. In the cotton filling of Manufacturing Example 1 (Sample A), there is a high frequency of pores (fine parts) smaller than 90 μm in diameter in the radial center, but the location of these fine parts can also be in the circumferential region. As described above, it was confirmed that there is a pore size distribution when there is a difference in the diameter distribution of the inscribed circles of the pores within the cotton filling in a certain region.

[0055] [Example 1 and Comparative Example 1] The following materials were used: cotton wicks (samples) A ​​and B obtained in manufacturing examples 1 and 2, a writing instrument having a nib conforming to the configuration and Figures 1 to 7, and writing ink of the composition described below. The dimensions of the nib were as shown below.

[0056] [Composition of the pen tip 20 (writing section 25, ink guide section 26, holder 30)] Writing section 25: Polyethylene sintered core, porosity: 50%, 4 x 3 x 6 mm, T=3 mm, W1=4 mm, W2=1.5 mm Ink guide section 26: PET fiber core, width: 2mm, length: 20mm, thickness t: 0.8mm

[0057] Holder 30: Made of acrylic resin, visible light transmittance 85% [Reflectance was measured using a multi-light source spectrophotometer (MSC-5N) manufactured by Suga Test Instruments Co., Ltd., and the visible light transmittance was determined from this.] Dimensions of the visible area (window) 33 (rectangle): S=3.8mm (maximum 4.5mm) × Y=8mm × width (thickness) 2.5mm

[0058] Writing instrument filling: Fillings A to D (φ6 × 80 mm) obtained in the above manufacturing examples 1 to 4 were used. Outer layer: PET film Writing instrument body 10, caps 50, 60: Made of polypropylene (PP) Pen tip 40: Polyester fiber bundle core, 60% porosity, φ2 x 40mm Friction material 52: Styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), and styrene-ethylene-butyl Styrene-based elastomers selected from the group consisting of diene-styrene (SEBS)

[0059] (Writing instrument ink composition: Ink color: Fluorescent pink) The following ink composition (total 100% by mass) was used as the ink for the writing instrument. Dispersion liquid: 50% by mass Triethanolamine: 2% by mass Ethylene glycol: 5% by mass Surfactant: 0.5% by mass Distilled water: 42.5% by mass pH: 4.0 Viscosity (25°C): 3.5 mPa·s (Complete viscometer, TOKIMEC TV-20) Surface tension (25°C): 35 mN / m (Automatic surface tension meter, Kyowa Interface Science Co., Ltd., DY-300)

[0060] In the writing instrument using the pen tip 20 of Example 1, which conforms to Figures 1 to 7, the cotton wick A has a distribution of two or more types of pore diameters, so that ink can be reliably supplied to the pen tips 20 and 40, and ink diffusion can be enhanced. Furthermore, the ink from the cotton wick A is guided to the writing section 25 by a thin, open-type ink guide section 26 that allows for leakage. The writing section 25 is made of a resin sintered core, and the ink guide section 26 is made of a fiber bundle core. The capillary force is strong relative to the porosity, and the thickness can be made extremely thin, resulting in good ink leakage. There is no need to design the ink guide section to be thick, and the minimum width S of the visible section 33 is 3.7 mm or more, and its length Y is 7.4 mm or more, so it is possible to maximize the effective area of ​​the visible section 33 that allows the writing direction to be seen, and achieve a high level of both visibility and ease of writing. Furthermore, since the ink guide section 26 is positioned towards the user during writing, even when using a natural writing angle, the visibility of the visible section 33 is improved regardless of the direction of writing. For example, a right-handed user writing from left to right can visually confirm the writing direction in the visible section 33 while drawing lines with the writing section 25. The ink flow is also good, and it was confirmed that a writing instrument can be obtained that achieves significantly improved visibility of the visible section 33 and ease of writing without compromising ink flow. It was also confirmed that the writing instrument could still be used without skipping even after being dropped from a height of 1 meter onto a cedar board.

[0061] Furthermore, when this writing instrument was set in an automatic writing device and tested according to the test method compliant with JIS S6037, a straight line was written on high-quality paper at a writing angle of 65°, a writing load of 1N, and a speed of 7cm / s. The condition of the written line was then visually inspected. It was found that because the above-mentioned preferred ink composition was used, the ink flow rate of the 20mm pen tip (10mg / m) was good, and while the drying of the pen tip was suppressed, the drying properties of the line and the low-temperature stability of the ink were excellent, resulting in a function that prevents bleeding and show-through of the line.

[0062] In contrast, the writing instrument in Comparative Example 1, which was equipped with cotton wick B without a pore size distribution, required more than an hour to supply ink to the 20 and 40 nibs. Furthermore, 5 out of 100 pens still had no ink impregnation in the nib even after one day, and were unable to supply ink. [Industrial applicability]

[0063] The writing instrument filling of this embodiment can be suitably applied as filling for marking-type writing instruments such as underline pens, oil-based markers, and water-based markers. [Explanation of symbols]

[0064] 10 Writing instrument body 11 Rear axle 16 front axis 17 Ink absorber 20 nibs 25 Writing section 26 Ink guide section 30 Holding body 33 Visible part

Claims

1. A writing instrument having cotton padding, wherein the cotton padding is characterized in that the frequency of areas occupied by voids with a maximum circle diameter of less than 90 μm, as measured by cross-sectional image analysis, is higher in the area inside the center with a radius of 0.5 mm than in the area outside the center.

2. The writing instrument according to claim 1, characterized in that the ink composition absorbed by the cotton lining is an ink composition containing a resin fine particle pigment containing a dye.

Images