Notebook

Abstract

Provided is a handwriting implement which achieves, to a high degree, both the maximization of an effective surface area of a visible portion which enables a handwriting direction to be visually confirmed, and an ease of handwriting.　Given as an example of this handwriting implement is a handwriting implement A comprising a pen tip 20 having a visible portion 33 which guides ink supplied from a handwriting implement body 10 and which enables a handwriting direction to be visually confirmed. The pen tip 20 includes at least: a handwriting portion 25; a holding body 30 having the visible portion 33; and an ink guiding portion 26 that guides ink of the handwriting implement body 10 to the handwriting portion 25. The handwriting implement A is characterized in that the minimum width X of the visible portion 33 is 3.7 mm or more, and the length Y of the visible portion 33 is 7.4 mm or more.　It is preferable that one ink guiding portion 26 is provided on one side of the visible portion 33; specifically, it is preferable that the ink guiding portion 26 is disposed on a front side during handwriting (side at which the pen tip 20 forms an obtuse angle with respect to the ink guiding portion 26).

Description

Technical Field

[0004] , ,

[0001] This specification relates to a writing instrument having a visible portion capable of visually recognizing the writing direction, and more particularly, to a writing instrument that highly balances the maximization of the effective area of the visible portion capable of visually recognizing the writing direction, the ease of viewing, and the ease of writing.

Background Art

[0002] As a writing instrument having a visible portion capable of visually recognizing the writing direction, the applicant of the present application has conventionally disclosed a writing instrument having a pen tip that guides and holds ink supplied from an ink absorber (wick) in a shaft body serving as a writing instrument body, and the pen tip is provided with a visible portion (visual recognition portion) capable of visually recognizing the writing direction (see, for example, Patent Documents 1 and 2). Since the pen tip of this type of writing instrument can visually recognize the writing portion, it can be firmly stopped at the portion where it is desired to stop after finishing writing, and can prevent over-drawing and overhanging.

[0003] However, the pen tip in Patent Document 1 has a U-shaped writing core integrally formed from a writing portion and ink guiding portions formed on both sides of the writing portion. In order to efficiently supply a sufficient amount of ink induction from the ink absorber, it is necessary to design the thickness of the ink guiding portion thick. However, when the ink guiding portion is thickened, the visible portion is obstructed by the pair of thickened ink guiding portions, resulting in a problem that the effective area of the visual recognition portion with respect to the entire pen tip becomes low. Also, in the writing instrument of Patent Document 2, the pen tip has an L-shaped writing core integrally formed from a writing portion and an ink guiding portion formed on one side of the writing portion. Although the effective area of the visible portion with respect to the entire pen tip has been somewhat improved, the visible portion is still narrow and it is somewhat difficult to visually recognize characters of a certain size (10.5 points or more).

[0004] On the other hand, as prior arts such as a pen tip having a visible portion capable of visually recognizing the writing direction other than the above structure, for example, the following 1) to 3) are disclosed. 1) To provide a writing instrument that is configured so that the writing part does not come into contact with a ruler and can be easily manufactured, a writing instrument is disclosed comprising: a writing instrument body extending in a predetermined direction; an ink guiding part extending in the axial direction of the writing instrument body and guiding ink contained in the writing instrument body; a writing part connected to the tip side of the ink guiding part and capable of writing cursive using the ink guided to the ink guiding part; a holder having a holding part for holding the writing part and a mounting part attached to the writing instrument body, wherein the holding part has an open tip side and at least one side side has a wall formed along the side of the writing part so that the tip of the writing part protrudes toward the tip side so that cursive can be written; the ink guiding part and the writing part constitute a writing core formed in a substantially L shape; and the holder has a visible part that allows the writing direction to be seen when writing (see, for example, Patent Document 3).

[0005] 2) In order to provide a writing instrument that combines visibility from the visible part with ease of writing, the writing instrument comprises: a writing instrument body having an ink-holding part inside for holding ink; an ink-guiding part extending from the writing instrument body toward the tip and guiding the ink from the ink-holding part toward the tip; a writing tip having a writing part provided at the tip of the ink-guiding part; and a visible part provided below the ink-guiding part between the writing part and the writing instrument body, wherein the writing part is provided at an acute or obtuse angle with respect to the ink-guiding part and has a contact part that contacts the writing surface, and the length from the lower end to the upper end of the contact part is a, A writing instrument is disclosed such that when the distance Z1 is the distance between a line passing through the center between the lower and upper ends of the contact portion and extending in the axial direction of the writing instrument body, and a line passing through the center between the lower end of the writing portion and the upper end of the visible portion and extending in the axial direction, (Z1 / a) × 100 ≤ 10.0; and a core holder comprising a holding portion for holding the ink guide portion and the visible portion, wherein when the vertical width of the portion including the core holder and the writing core is the pen tip width b, (b / a) × 100 ≤ 150; and the thickness t of the thin portion of the visible portion is 0.8 mm ≤ t ≤ 1.0 mm (see, for example, Patent Document 4).

[0006] 3) To provide a writing instrument that achieves both visibility from the visible part and ease of writing, a writing instrument is disclosed comprising: a writing instrument body having an ink-holding part inside for holding ink; an ink-guiding part extending from the writing instrument body toward the tip and guiding the ink from the ink-holding part toward the tip; a writing part provided at the tip of the ink-guiding part; and a visible part provided between the writing part and the writing instrument body, wherein the writing part is provided at an acute or obtuse angle with respect to the axial direction of the writing instrument body and has a contact part that contacts the writing surface, the tip surface of the writing instrument body is inclined with respect to a plane perpendicular to the axial direction, and the contact part and the tip surface are substantially parallel (see, for example, Patent Document 5).

[0007] However, the writing instruments described in Patent Documents 3 to 5 above describe technologies adjacent to the present disclosure and mainly disclose an L-shaped writing tip integrally composed of a writing section and an ink-guiding section formed on one side of the writing section. The ink-guiding section is not located on the front side when writing, but on the back side (upper side). Therefore, for example, when marking characters printed on paper from left to right, the ink crosses the characters in the direction of writing, obscuring some of the characters, which presents problems such as difficulty in writing. Furthermore, the writing instruments described in Patent Documents 4 and 5 attempt to achieve both visibility from the visible part and ease of writing by resolving the misalignment of the axial centerlines between the writing part and the visible part provided above the writing part through numerical limitations based on specific inequalities. However, the numerical ranges determined by these inequalities overlap with those of existing pen tips with visible parts, and moreover, these inequalities do not aim to maximize the effective area of ​​the visible part by considering the shape, material, and mounting structure of the ink guide part, and thus differ from the technical concept (configuration and its effects) of the present disclosure. Furthermore, the width (thickness) of the ink guide portion in each writing instrument described in Patent Documents 4 and 5 is 1.5 mm or more in the examples, and since the ink guide portion is not located on the side facing the user during writing, the width of the visible portion is narrower than the width of the writing line, leaving room for further improvement. Currently, there is a strong desire for a writing instrument that maximizes the effective area of ​​the visible portion that allows the user to visually confirm the writing direction across the entire pen tip, as well as providing a high level of visibility and ease of writing. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2000-52682 (Claims, Figure 1, etc.) [Patent Document 2] Japanese Patent Publication No. 2019-206151 (Claims, Figure 3, etc.) [Patent Document 3] Japanese Patent Publication No. 2020-59247 (Claims, Figure 1, etc.) [Patent Document 4] Japanese Patent Publication No. 2020-196166 (Claims, Figure 4, etc.) [Patent Document 5] Japanese Patent Publication No. 2020-196246 (Claims, Figure 4, etc.) [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] This disclosure aims to address the problems of the prior art described above and to provide a writing instrument having a pen tip that allows the writing direction to be seen, which achieves a high degree of balance between maximizing the effective area of ​​the visible part that allows the writing direction to be seen, ease of viewing, and ease of writing. [Means for solving the problem]

[0010] As a result of diligent research to solve the above-mentioned conventional problems, the present inventors have found that a writing instrument can be obtained by providing a pen tip with a visible portion that guides ink supplied from the writing instrument body and allows the writing direction to be visually confirmed, and by giving the pen tip a specific structure, etc., and have completed this disclosure.

[0011] In other words, the writing instrument of the present disclosure comprises a pen tip having a visible portion that guides ink supplied from the writing instrument body and allows the writing direction to be visually confirmed, wherein the pen tip comprises at least a writing portion, a holder having a visible portion, and an ink guiding portion that guides ink from the writing instrument body to the writing portion, characterized in that the minimum width of the visible portion is 3.7 mm or more and the length of the visible portion is 7.4 mm or more. The ink guide portion is preferably located on one side of the visible portion. Furthermore, the writing instrument of this disclosure includes a pen tip having a visible portion that guides ink supplied from the writing instrument body and allows the writing direction to be visually confirmed, wherein the pen tip comprises at least a writing portion, a holder having a visible portion, and an ink guiding portion that guides ink from the writing instrument body to the writing portion, and the ink guiding portion is provided on the side facing the user during writing. It is preferable that the width of the ink guide portion is less than 1.5 mm when viewed from the vertical surface of the visible portion. Preferably, the ink guiding portion is composed of a fiber bundle core having a rectangular or elliptical cross-section, the writing portion is composed of a resin sintered body, and the ink guiding portion and the writing portion are fixed to the holder, and the ink guiding portion and the writing portion are fixed in contact with each other. [Effects of the Invention]

[0012] According to this disclosure, a writing instrument is provided that achieves a high degree of balance between maximizing the effective area of ​​the visible part that allows the writing direction to be seen, ease of viewing, and ease of writing. The objects and effects of the present disclosure are recognized and obtained by using the components and combinations particularly pointed out in the claims. Both the above general description and the following detailed description are exemplary and explanatory, and do not limit the present disclosure described in the claims.

Brief Description of Drawings

[0013] [Figure 1] It is a drawing of a writing instrument showing an example of an embodiment of the present disclosure, where (a) is a front view, (b) is a plan view, (c) is a longitudinal sectional view in a front view, and (d) is a longitudinal sectional view of (b). [Figure 2] It is a drawing showing the state where the cap is removed from the writing instrument of FIG. 1, where (a) is a plan view, (b) is a left side view, (c) is a front view, (d) is a right side view, (e) is a bottom view, (f) is a longitudinal sectional view of (c), and (g) is a longitudinal sectional view of (e). [Figure 3] It is a partially enlarged drawing showing the pen tip side which is a main part of the writing instrument of FIG. 1, where (a) is a front view and (b) is its longitudinal sectional view. [Figure 4] (a) is a perspective view of the pen tip of the writing instrument of FIG. 3 seen from the front side, and (b) is a perspective view of the pen tip seen from the rear side. [Figure 5] It is a partially enlarged drawing of the pen tip of the writing instrument of FIG. 3 rotated 180°, where (a) is a perspective view seen from the front side and (b) is a perspective view of the pen tip seen from the rear side. [Figure 6] It is an exploded perspective view showing an example of the attachment mode of the ink guiding part and the writing part constituting the pen tip to the holder of the writing instrument of FIG. 1 and the attachment mode to the front shaft of this holder. [Figure 7] They are drawings showing an example of the writing instrument body (shaft cylinder), where (a) is a perspective view seen from the front side, (b) is a plan view, (c) is a left side view, (d) is a front view, (e) is a right side view, and (f) is a longitudinal sectional view. [Figure 8]These are drawings showing an example of a tip shaft used in a writing instrument. (a) is a perspective view seen from the front side, (b) is a plan view, (c) is a left side view, (d) is a front view, (e) is a right side view, (f) is an enlarged perspective view showing the inclined opening of the tip shaft on the front side, (g) is a longitudinal sectional view, (h) is a perspective view seen from the rear side, and (i) is a bottom view. [Figure 9] These are drawings showing an example of a holder having a visible portion of a pen tip used in 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 on the front side, (h) is a longitudinal sectional view, (i) is a perspective view seen from above on the rear side, and (j) is a bottom view. [Figure 10] This is a drawing explaining an example of the usage state of the writing instrument of the present disclosure. (a) is an explanatory drawing explaining that since the visible portion is significantly wider than the conventional one, for example, even when viewing characters of 10.5 pt (Mincho typeface) from above at a writing angle of 60°, they can be clearly visually recognized within the visible portion. (b) is a perspective view showing an example of a state where actually printed characters are being marked. [Figure 11] This is a drawing of a writing instrument showing another example (Second Embodiment) of the embodiment of the present disclosure (a drawing conforming to FIG. 2 showing the state where the cap is removed). (a) is a plan view, (b) is a left side view, (c) is a front view, (d) is a right side view, (e) is a bottom view, (f) is a longitudinal sectional view of (c), and (g) is a longitudinal sectional view of (e). [Figure 12] (a) is a perspective view of the pen tip of the writing instrument in FIG. 11 seen from the front side, and (b) is a perspective view of the pen tip seen from the rear side. [Figure 13] This is a drawing of the pen tip of the writing instrument in FIG. 12 seen after rotating it 180°. (a) is a perspective view seen from the front side, and (b) is a perspective view of the pen tip seen from the rear side. [Figure 14] This is a drawing showing the pen tip portion of the writing instruments in FIGS. 11 to 13. (a) is a longitudinal sectional view at the center in the width direction, (b) is a plan view, (c) is a perspective view seen from the front side, (d) is a left side view, (e) is a front view, (f) is a right side view, and (g) is a bottom view. [Figure 15]These are drawings of a writing instrument showing another embodiment of the present disclosure (a third embodiment) (drawings corresponding to Figures 2 and 11, showing the cap removed), where (a) is a top view, (b) is a left side view, (c) is a front view, (d) is a right side view, (e) is a bottom view, and (f) is a longitudinal cross-sectional view of (c). [Figure 16] (a) is a perspective view of the pen tip of the writing instrument shown in Figure 15, viewed from the front, and (b) is a perspective view of the pen tip, viewed from the rear. [Figure 17] Figure 16 shows the pen tip of the writing instrument rotated 180°, with (a) being a perspective view from the front and (b) being a perspective view of the pen tip from the rear. [Figure 18] Figures 15 to 17 are diagrams showing the pen tip portion of the writing instrument, where (a) is a vertical cross-section in the width direction, (b) is a plan view, (c) is a perspective view from the front, (d) is a left side view, (e) is a front view, (f) is a right side view, and (g) is a bottom view. [Figure 19] These are drawings of a writing instrument showing another embodiment of the present disclosure (a fourth embodiment) (drawings corresponding to Figures 2, 11, and 15, showing the cap removed), where (a) is a top view, (b) is a left side view, (c) is a front view, (d) is a right side view, (e) is a bottom view, (f) is a longitudinal section of (c), and (g) is a longitudinal section of (e). [Figure 20] (a) is a perspective view of the pen tip of the writing instrument shown in Figure 18, viewed from the front, and (b) is a perspective view of the pen tip, viewed from the rear. [Figure 21] Figure 20 shows the pen tip of the writing instrument rotated 180°, with (a) being a perspective view from the front and (b) being a perspective view of the pen tip from the rear. [Figure 22] Figures 19 to 21 are diagrams showing the pen tip portion of the writing instrument, where (a) is a vertical cross-section in the width direction, (b) is a plan view, (c) is a perspective view from the front, (d) is a left side view, (e) is a front view, (f) is a right side view, and (g) is a bottom view. [Figure 23]The following are drawings of a writing instrument showing another embodiment of the present disclosure (a fifth embodiment) (drawings corresponding to Figures 2, 11, 15, and 19, showing the cap removed), where (a) is a top view, (b) is a left side view, (c) is a front view, (d) is a right side view, (e) is a bottom view, (f) is a longitudinal section of (c), and (g) is a longitudinal section of (e). [Figure 24] (a) is a perspective view of the pen tip of the writing instrument shown in Figure 23, viewed from the front, and (b) is a perspective view of the pen tip, viewed from the rear. [Figure 25] Figure 24 shows the pen tip of the writing instrument rotated 180°, with (a) being a perspective view from the front and (b) being a perspective view of the pen tip from the rear. [Figure 26] Figures 23 to 25 are diagrams showing the pen tip portion of the writing instrument, where (a) is a vertical cross-section in the width direction, (b) is a plan view, (c) is a perspective view from the front, (d) is a left side view, (e) is a front view, (f) is a right side view, and (g) is a bottom view. [Figure 27] The following are drawings of a writing instrument showing another embodiment of the present disclosure (sixth embodiment) (drawings corresponding to Figures 2, 11, 15, 19, and 23, showing the cap removed), where (a) is a top view, (b) is a left side view, (c) is a front view, (d) is a right side view, (e) is a bottom view, and (f) is a longitudinal cross-sectional view of (c). [Figure 28] (a) is a perspective view of the pen tip of the writing instrument shown in Figure 27, viewed from the front, and (b) is a perspective view of the pen tip, viewed from the rear. [Figure 29] Figure 28 shows the pen tip of the writing instrument rotated 90°, with (a) being a perspective view from the front and (b) being a perspective view of the pen tip from the rear. [Figure 30] Figures 27 to 29 are diagrams showing the pen tip portion of the writing instrument, where (a) is a vertical section view in the width direction, (b) is a plan view, (c) is a perspective view seen from the front, (d) is a left side view, (e) is a front view, (f) is a right side view, and (g) is a bottom view. [Modes for carrying out the invention]

[0014] The embodiments of this disclosure will be described in detail below with reference to the drawings. However, it should be noted that the technical scope of this disclosure is not limited to each of the embodiments detailed below, but extends to the invention described in the claims and its equivalents. In each figure, "front" refers to the direction of the tip of writing instruments A-F and their 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 commonly used between each drawing (between Figures 1-30) represent the same components or members, even if not specifically mentioned in the description of each drawing.

[0015] (First embodiment: overall configuration) Figures 1 to 10 are drawings illustrating a marking pen type writing instrument according to the first embodiment of this disclosure, the writing instrument body, barrel, nib, and an example of its usage state, 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 to protect the pen tip 20 and a cap 60 to protect the pen tip 40 are attached to both sides of the writing instrument body 10.

[0016] (Writing instrument body 10, rear shaft 11) As shown in Figures 1 to 5 and 7(a) to 7(f), 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 drawing, is a reduced-diameter holding part 12 having a fitting part for fixing a holder 45 that holds a fine-point rod-shaped pen tip 40 by fitting. A cap 60 is detachably attached to the large-diameter outer circumference of this holding part 12. Furthermore, as shown in Figures 7(a) to (f), a front shaft 16 is fixed to the opening 13 at the other end of the rear shaft 11, which is on the left side, by fitting or other means, and 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.

[0017] (first axis 16) As shown in Figures 1 to 5 and 8(a) to (i), 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 side of the front portion 16c, a projection 16e inside the inclined opening 16d for ensuring that the ink guide portion 26 is directed towards the central part of the ink absorbent body 17, and an annular contact portion 16f for contacting the rear end of the holder 30, and inside the cylindrical body on the rear side where the inclined opening 16d continues, there are retaining projections 16h, 16h... that hold the elliptical ink absorbent body 17 at predetermined intervals on the elliptical outer peripheral surface 16g. Reference numeral 16a1 indicates an inclined surface on the rear end surface of the flange portion 16a that slightly corresponds to the plane 14 of the rear axle 11, for the purpose of alignment with the rear axle 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.

[0018] (Ink absorbent 17) The ink-absorbing body 17 is impregnated with writing instrument ink such as water-based ink, oil-based ink, or thermochromic ink. For example, it may be a fiber bundle made of one or more types of materials such as natural fibers, animal hair fibers, polyacetal resin, acrylic resin, polyester resin, polyamide resin, polyurethane resin, polyolefin resin, polyvinyl resin, polycarbonate resin, polyether resin, or polyphenylene resin, processed fiber bundles such as felt, or porous bodies such as sponges, resin particles, or sintered bodies. This ink-absorbing body 17 is housed and held within the writing instrument body 10. An outer film 17a is attached to the outer periphery of the ink-absorbing body 17.

[0019] (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. These inks are preferable because, by adjusting the types and amounts of ink components, they achieve an ink viscosity (25°C: complate-type viscometer) of 1-5 mPa·s, a surface tension of 30-60 mN / m, an ink flow rate X from the pen tip 20 of 5-20 mg / m, and an ink flow rate Y from the pen tip 40 of 0.1-5 mg / m, with X > Y, making it easy to differentiate between handwriting styles. The ink flow rate was measured by setting the pen body in an automatic writing device and, in accordance with JIS S6037, on high-quality paper at a writing angle of 65°, a writing force of 1 N, and a speed of 7 cm / s. Furthermore, by making the bending stress of the pen tip 40 higher than that of the pen tip 20, a writing instrument suitable for writing fine characters with the pen tip 40 can be provided.

[0020] When using thermochromic ink as ink for writing instruments, it is preferable to use a reversible thermochromic aqueous ink composition comprising at least a reversible thermochromic microcapsule pigment containing a reversible thermochromic composition comprising (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction of the two occurs, water, and a water-soluble polymer flocculant, with the pH of the ink composition in the range of 3 to 7. The microcapsule pigment may have a circular or non-circular cross-sectional shape. The average particle size of the microcapsule pigment is the D50 value calculated using a particle size analyzer [Microtrac HRA9320-X100 (manufactured by Nikkiso Co., Ltd.)] with a refractive index of 1.81 and based on volume, preferably 0.5 to 5.0 μm, and more preferably 1 to 3 μm. If the average particle size exceeds 5.0 μm, ink flowability decreases and adhesion to the writing surface tends to decline. On the other hand, if the average particle size is less than 0.5 μm, it becomes difficult to achieve high-density color development. Furthermore, if the ratio of the reversible thermochromic composition to the wall film becomes too large, the wall film becomes too thin, leading to a decrease in resistance to pressure and heat. Conversely, if the ratio of the wall film to the reversible thermochromic composition becomes too large, a decrease in color density and vividness during color development is unavoidable. Therefore, a reversible thermochromic composition / wall film ratio of 6 / 1 to 1 / 1 (mass ratio) is preferable.

[0021] The reversible thermochromic microcapsule pigment can be contained in the total amount of the ink composition in an amount of 2 to 50% by mass, preferably 5 to 40% by mass, and more preferably 10 to 30% by mass. If the content is less than 2% by mass, the color density will be insufficient, and if it exceeds 50% by mass, the ink flowability will decrease and writing performance will be impaired. Furthermore, by using a color-memory-retaining microcapsule pigment containing an ester compound as the reaction medium that determines the temperature at which the color reaction occurs, and which alternately stores the colored state or the decolorized state within a specific temperature range, it is possible to obtain a reversible thermochromic aqueous ink that exhibits good writing performance without impairing ink flow during writing, even when left in an environment below 0°C where the ink freezes, or when containing ink that changes color in the temperature range where the ink freezes and is put into practical use, and thus the writing does not become faint or faded. The ester compound is an ester compound composed of an alcohol compound having two aromatic rings in its molecule and a saturated or unsaturated fatty acid having 4 or more carbon atoms.

[0022] The solvent used in the aforementioned ink is water and, if necessary, a water-soluble organic solvent. Examples of the aforementioned water-soluble organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulforane, 2-pyrrolidone, and N-methyl-2-pyrrolidone.

[0023] By adding a polymer flocculant to the ink, the flocculant causes a loose bridging effect between microcapsule pigment particles, resulting in a loosely aggregated state. In ink exhibiting such a loosely aggregated state, separation of microcapsule pigment does not occur in the capillary spaces of the ink storage body (cotton) made of a fiber bundle and the marking pen body made of a resin bundle of fibers. Therefore, by preventing the separation of microcapsule pigments due to upright or inverted storage, and thus suppressing the darkening or lightening of the handwriting, a marking pen with storage performance equivalent to that of a marking pen filled with dye ink can be obtained. Nonionic water-soluble polymer compounds can be used as the aforementioned water-soluble polymer flocculant, and examples include polyvinylpyrrolidone, polyethylene oxide, and water-soluble polysaccharides. Examples of the aforementioned water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, and nonionic water-soluble cellulose derivatives. Specific examples of nonionic water-soluble cellulose derivatives include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, and hydroxypropylmethylcellulose. In reversible thermochromic aqueous ink compositions, any water-soluble polymer that exhibits a loose bridging effect between microcapsule pigment particles can be used, but nonionic water-soluble cellulose derivatives are the most effective.

[0024] In addition, rust inhibitors such as benzotriazole, toltriazole, dicyclohexylammonium nitride, diisopropylammonium nitride, and saponins may be used as needed; preservatives or fungicides such as carbolic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl parahydroxybenzoate, and 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine may be used; urea, nonionic surfactants, reduced or non-reduced starch hydrolysates, oligosaccharides such as trehalose, sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, and sodium pyrophosphate may be used; humectants, defoamers, dispersants, and fluorinated surfactants or nonionic surfactants may be used to improve ink penetration.

[0025] The ink composition obtained as described above has its pH adjusted to 3-7. By adjusting the ink composition to an acidic range, aggregation and sedimentation of the contained reversible thermochromic microcapsule pigments at low temperatures can be suppressed. When the pH exceeds 7, the ink's flowability is easily impaired when left in low-temperature ranges, i.e., temperatures at which the ink freezes. Conversely, when the pH is below 3, the reversible thermochromic composition contained within the capsule develops stronger color, making it more likely to cause problems such as color residue when the color fades.

[0026] Furthermore, as shown in Figures 1(c) and (d), for example, a friction body 52 made of a cylindrical thermoplastic elastomer with an erasing ability (erasing rate) of less than 70% of pencil lines as specified in JIS S 6050-2002 can be fixed to the recess 51 of the cap 50. The friction body 52 generates frictional heat easily through its rubbing action and has low wear, thereby reducing the generation of eraser residue during rubbing and preventing contamination of the surrounding area. The friction body 52 is preferably configured as described below in order to be able to discolor images with thermochromic properties well by rubbing (i.e., to provide good discoloration properties), and to reduce paper contamination by preventing the friction body from breaking due to strong force and / or repeated rubbing operations.

[0027] The friction element has a compression set at 120°C (hereinafter also referred to as "120°C compression set") of 80% or less. A low 120°C compression set is an indicator of good deformation recovery of the friction element under abrasion conditions (i.e., high-temperature conditions), and this good deformation recovery contributes to maintaining good wear resistance of the friction element, especially under abrasion conditions (i.e., high-temperature conditions).

[0028] The compression set at 120°C is 80% or less, and may be 70% or less, or 60% or less, from the viewpoint of good wear resistance of the friction material under high-temperature conditions. A smaller compression set at 120°C is preferable from the viewpoint of wear resistance under high-temperature conditions. In this disclosure, the compression set is a value measured in accordance with JIS K6262-2013.

[0029] Generally, the compression set of a molded article formed from an elastomer tends to increase with increasing temperature. The friction material of this disclosure has a small 120°C compression set, such as within the specified range described above. From the viewpoint of obtaining such a 120°C compression set, it is advantageous to reduce the temperature dependence of the compression set in the friction material. In the friction material, the ratio (A) / (B) of the compression set at 120°C to the compression set at 70°C (B) may be 1.0 to 1.7, 1.0 to 1.5, 1.0 to 1.4, or 1.0 to 1.3.

[0030] The friction element has a Shore A hardness of 60 to 98. The Shore A hardness is 60 or higher, and may be 70 or higher, or 80 or higher, from the viewpoint of good discoloration of images with thermochromic properties and good wear resistance of the friction element. The Shore A hardness is 98 or lower, and may be 95 or lower, or 90 or lower, from the viewpoint of increasing the contact area with the paper surface by pressing the friction element against the paper surface, and thus easily obtaining good discoloration. In this disclosure, the Shore A hardness is a value measured in accordance with JIS K 6253-3-2012.

[0031] The composition of the material components constituting the friction body of this disclosure is designed to provide the desired 120°C compression set and Shore A hardness as described above. The friction body typically comprises an elastomer component and an additive component. Below are examples of material components suitable for forming a friction body in which both the 120°C compression set and Shore A hardness are controlled within the desired range of this disclosure, but the material components are not limited to those examples below.

[0032] [Elastomer component (Component (A))] Examples of elastomer components include styrene-based elastomers, polyester-based elastomers, and olefin-based elastomers. However, the elastomer component includes, and preferably consists of, a styrene-based elastomer, because it easily achieves the desired 120°C compression set and Shore A hardness.

[0033] In this disclosure, "styrene-based elastomer" means an elastomer containing styrene structural units in its main chain, and is typically a thermoplastic elastomer. From the viewpoint of easily achieving the desired 120°C compression set and Shore A hardness, the styrene-based elastomer is preferably a block copolymer (hereinafter referred to as a styrene-based block copolymer) having polymer blocks mainly composed of structural units derived from a styrene skeleton-containing compound and polymer blocks mainly composed of structural units derived from a conjugated diene compound, or a hydrogenated version of said block copolymer, or a mixture thereof. The above-mentioned "polymer block mainly composed of structural units derived from a styrene skeleton-containing compound (or conjugated diene compound)" means a polymer block in which the structural unit present in the highest mass proportion in the polymer block is a structural unit derived from a styrene skeleton-containing compound (or conjugated diene compound).

[0034] The above-mentioned styrene-based block copolymer is typically a block copolymer having one or more polymer blocks X, preferably two or more from the viewpoint of mechanical properties, which are mainly composed of structural units derived from a styrene skeleton-containing compound, and one or more polymer blocks Y, which are mainly composed of structural units derived from a conjugated diene compound. For example, block copolymers having structures such as XY, XYX, YXYX, and XYXYX can be mentioned.

[0035] The hydrogenated styrene-based block copolymer described above is obtained by adding hydrogen to the carbon-carbon double bonds in the styrene-based block copolymer to convert them into carbon-carbon single bonds. This hydrogenation can be carried out by known methods, for example, by hydrogenation using a hydrogenation catalyst in an inert solvent.

[0036] The hydrogenation rate of the hydrogenated styrene block copolymer described above (i.e., the ratio of the number of carbon-carbon single bonds produced by hydrogenation to the number of carbon-carbon double bonds in the styrene block copolymer before hydrogenation) may be 50% or more, 70% or more, or 90% or more, from the viewpoint of improving erasing performance, paper surface stain resistance, and abrasion resistance. Unless otherwise specified, the above hydrogenation rate refers to the value measured by 1H-NMR.

[0037] The styrene skeleton-containing compound is a polymerizable monomer having a polymerizable carbon-carbon double bond and an aromatic ring. Examples of the styrene skeleton-containing compound include styrene, t-butylstyrene, α-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, p-tertiary butylstyrene, and alkylstyrene in which at least one C1-C8 alkyl group is bonded to a benzene ring. Among these, styrene and alkylstyrene in which at least one C1-C8 alkyl group is bonded to a benzene ring are preferred. One or more of these can be used as the styrene skeleton-containing compound.

[0038] Examples of alkylstyrenes in which at least one C1-C8 alkyl group is bonded to a benzene ring include alkylstyrenes such as o-alkylstyrene, m-alkylstyrene, p-alkylstyrene, 2,4-dialkylstyrene, 3,5-dialkylstyrene, and 2,4,6-trialkylstyrene, as well as halogenated alkylstyrenes in which one or more hydrogen atoms of the alkyl group in these alkylstyrenes are substituted with halogen atoms. More specifically, examples include o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-diethylstyrene, 3,5-diethylstyrene, 2,4,6-triethylstyrene, o-propylstyrene, m-propylstyrene, p-propylstyrene, 2,4-dipropylstyrene, 3,5-dipropylstyrene, 2,4,6-tripropylstyrene, 2-methyl-4-ethylstyrene, 3-methyl-5-ethylstyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene, 2,4-bis(chloromethyl)styrene, 3,5-bis(chloromethyl)styrene, 2,4,6-tri(chloromethyl)styrene, o-dichloromethylstyrene, m-dichloromethylstyrene, and p-dichloromethylstyrene. Among these, p-methylstyrene is particularly preferred from the viewpoint of crosslinking properties. Alkylstyrene in which at least one C1-C8 alkyl group is bonded to a benzene ring is suitably used as a material for crosslinked styrene-based elastomers.

[0039] In the polymer block X described above, the proportion of alkylstyrene in which at least one of the C1-C8 alkyl groups is bonded to a benzene ring is preferably 1% by mass or more, more preferably 50% by mass or more, and may even be 100% by mass, from the viewpoint of crosslinkability.

[0040] The above-mentioned conjugated diene compound is a polymerizable monomer having a structure in which two carbon-carbon double bonds are connected by one carbon-carbon single bond. Examples of the above-mentioned conjugated diene compound include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and chloroprene (2-chloro-1,3-butadiene). Among these, 1,3-butadiene and isoprene are preferred. One or more of these can be used as the above-mentioned conjugated diene compound.

[0041] The content of constituent units derived from the styrene skeleton-containing compound in the above-mentioned styrene-based block copolymer or its hydrogenated product is not particularly limited, but may be 5 to 50% by mass or 20 to 40% by mass from the viewpoint of mechanical strength, cold resistance, heat resistance and flexibility.

[0042] The polymer block X is preferably a polymer block derived solely from the styrene skeleton-containing compound, or a copolymer block of the styrene skeleton-containing compound and the conjugated diene compound. When the polymer block X is the copolymer block, the content of constituent units derived from the styrene skeleton-containing compound in the polymer block X is not particularly limited, but from the viewpoint of heat resistance, it is usually 50% by mass or more, and may be 70% by mass or more, or 90% by mass or more. The distribution of constituent units derived from the conjugated diene compound in the polymer block X is not particularly limited. When there are two or more polymer blocks X in a styrene-based elastomer molecule, they may have the same structure or they may have different structures.

[0043] The polymer block Y is preferably a polymer block consisting only of the conjugated diene compound, or a copolymer block of the styrene skeleton-containing compound and the conjugated diene compound. When the polymer block Y is the copolymer block, the content of constituent units derived from the conjugated diene compound in the polymer block Y is not particularly limited, but from the viewpoint of heat resistance, it is usually 50% by mass or more, and may be 70% by mass or more, or 90% by mass or more. The distribution of constituent units derived from the styrene skeleton-containing compound in the polymer block Y is not particularly limited. The bonding mode between the conjugated diene compound and the styrene skeleton-containing compound is not particularly limited. When there are two or more polymer blocks Y in a styrene-based elastomer molecule, they may have the same structure or they may have different structures.

[0044] Examples of the styrene-based block copolymers mentioned above include styrene-butadiene-styrene block copolymer (SBS) and styrene-isoprene-styrene block copolymer (SIS).

[0045] Examples of hydrogenated styrene-based block copolymers include styrene-ethylene-butene copolymer (SEB), styrene-ethylene-propylene copolymer (SEP), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS), and styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS). Among these, styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), and styrene-ethylene-butadiene-styrene (SEBS) are preferred, and in particular, styrene-ethylene-propylene-styrene copolymer (SEPS) and styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS) are preferred from the viewpoint of abrasion resistance.

[0046] The styrene-based block copolymers and / or hydrogenated thereof listed above can be used individually or as a mixture of two or more.

[0047] Styrene elastomers may be crosslinked. Increasing the degree of crosslinking contributes to reducing the 120°C compression set and increasing the Shore A hardness. In this case, SEBS, SEPS, and SEEPS, in which styrene is replaced with p-methylstyrene, are preferred from the viewpoint of heat resistance and abrasion resistance. Whether or not a styrene elastomer is crosslinked can be distinguished by visually observing whether or not gel remains after immersion in 120°C hot xylene for 24 hours, or by measuring the remaining weight. For example, the crosslinking agent (component (E)) described later can be used for crosslinking. In the exemplary embodiment, the friction body may not contain polymers other than the crosslinked styrene elastomer that are insoluble in 120°C hot xylene. In this case, whether or not the styrene elastomer is crosslinked can also be evaluated by subjecting the friction body to the above-described hot xylene treatment.

[0048] The mass-average molecular weight (Mw) of the styrene-based elastomer is preferably 150,000 to 500,000. The mass-average molecular weight may be 150,000 or more, 180,000 or more, or 200,000 or more, from the viewpoint of obtaining a friction material with good wear resistance. On the other hand, the mass-average molecular weight may be 500,000 or less, 450,000 or less, or 400,000 or less, from the viewpoint of good processability during the manufacture of the friction material. In this disclosure, unless otherwise specified, molecular weight refers to the polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0049] [Other ingredients] Other components may include, for example, one or more of the following: propylene resin (hereinafter referred to as component (B)), rubber softener (hereinafter referred to as component (C)), lubricant (hereinafter referred to as component (D)), crosslinking agent (hereinafter referred to as component (E)), crosslinking aid (hereinafter referred to as component (F)), colorant (hereinafter referred to as component (G)), polymer components other than the propylene resin mentioned above, stabilizers, fillers, etc.

[0050] [Propylene resin (component (B))] The use of a propylene-based resin (component (B)) is advantageous in improving the wear resistance and paper surface stain resistance of the friction body. Examples of component (B) include propylene homopolymers, propylene random copolymers, and propylene block copolymers, which can be used individually or in combination of two or more. From the viewpoint of heat resistance, propylene homopolymers and propylene block copolymers are more preferred, and propylene homopolymers are even more preferred.

[0051] Propylene homopolymer is a polymer composed solely of propylene units, and is most preferred as component (B) due to its high crystallinity and melting point.

[0052] Examples of propylene-based random copolymers include propylene-ethylene random copolymers obtained by copolymerizing propylene and ethylene, propylene-α-olefin random copolymers obtained by copolymerizing propylene and at least one α-olefin having 4 to 20 carbon atoms, and propylene-ethylene-α-olefin random copolymers obtained by copolymerizing propylene, ethylene and at least one α-olefin having 4 to 20 carbon atoms.

[0053] Examples of α-olefins with 4 to 20 carbon atoms include 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, and dimethyl Examples include -1-pentene, ethyl-1-pentene, trimethyl-1-butene, methylethyl-1-butene, 1-octene, methyl-1-pentene, ethyl-1-hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl-1-pentene, propyl-1-pentene, diethyl-1-butene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene. The α-olefins having 4 to 20 carbon atoms are preferably 1-butene, 1-pentene, 1-hexene, and 1-octene, and more preferably 1-butene and 1-hexene.

[0054] Specific examples of propylene-based random copolymers include, for example, propylene-ethylene random copolymer, propylene-1-butene random copolymer, propylene-1-hexene random copolymer, propylene-1-octene random copolymer, propylene-ethylene-1-butene random copolymer, propylene-ethylene-1-hexene random copolymer, and propylene-ethylene-1-octene random copolymer, and preferably propylene-ethylene random copolymer, propylene-1-butene random copolymer, propylene-1-hexene random copolymer, propylene-ethylene-1-butene random copolymer, and propylene-ethylene-1-hexene random copolymer.

[0055] Examples of propylene-based block copolymers include block copolymers composed of crystalline propylene polymer moieties and amorphous propylene-α-olefin copolymer moieties.

[0056] Examples of crystalline propylene polymers include propylene homopolymers or random copolymers of propylene with small amounts of other α-olefins.

[0057] On the other hand, examples of amorphous propylene-α-olefin copolymers include amorphous random copolymers of propylene and other α-olefins. Preferred other α-olefins have 2 or 4 to 12 carbon atoms, and specific examples include ethylene, 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, vinylcyclopentane, and vinylcyclohexane. These α-olefins can be used individually or in combination of two or more.

[0058] In addition to the other α-olefins mentioned above, ternary or quaternary or more copolymers obtained by copolymerizing non-conjugated dienes such as 1,4-hexadiene, 5-methyl-1,5-hexadiene, 1,4-octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, and 5-isopropenyl-2-norbornene can also be used as propylene-based block copolymers.

[0059] The melt mass flow rate of component (B) above may be 0.01 to 100 g / 10 min, 0.1 to 50 g / 10 min, or 0.3 to 10 g / 10 min when measured under conditions of 230°C and 21.18 N in accordance with JIS K 7210-1999, from the viewpoint of moldability.

[0060] Furthermore, the melting point of component (B) may be 150°C or higher, or 160°C or higher, from the viewpoint of heat resistance. There is no particular upper limit to the melting point, but since it is a polypropylene resin, the upper limit is approximately 167°C. The above melting point refers to the peak-top melting point of the peak that appears on the highest temperature side in the second melting curve (i.e., the melting curve measured during the final heating process) when measured using a DSC type differential scanning calorimeter (e.g., Diamond from PerkinElmer Japan Co., Ltd.) with a program of holding at 230°C for 5 minutes → cooling to -10°C at 10°C / min → holding at -10°C for 5 minutes → heating to 230°C at 10°C / min.

[0061] The amount of component (B) can be 30 to 300 parts by mass, 35 to 250 parts by mass, or 40 to 180 parts by mass per 100 parts by mass of component (A). This range provides a good balance of flexibility, abrasion resistance, and paper surface stain resistance.

[0062] [Rubber softener (component (C))] Various compounds that are understood by those skilled in the art to function as a rubber softener (component (C)) can be used. The use of component (C) is advantageous in improving the flexibility of the friction material. Component (C) is typically a non-aromatic rubber softener. Examples of non-aromatic rubber softeners are non-aromatic mineral oils (i.e., hydrocarbon compounds derived from petroleum, etc., that are not classified as aromatic in the classification described below (i.e., have less than 30% aromatic carbon atoms)) or non-aromatic synthetic oils (i.e., synthetic hydrocarbon compounds that do not use aromatic monomers). Non-aromatic rubber softeners are usually liquid, gel-like, or gum-like at room temperature.

[0063] Mineral oils used as component (C) are mixtures of compounds having one or more paraffin chains, naphthenic rings, and aromatic rings. Based on the number of carbon atoms, those with 30-45% naphthenic rings are called naphthenic mineral oils, those with 30% or more aromatic rings are called aromatic mineral oils, and those that do not belong to either naphthenic or aromatic mineral oils, and have 50% or more paraffin chains based on the number of carbon atoms, are distinguished as paraffinic mineral oils.

[0064] Examples of the above component (C) include paraffinic mineral oils such as linear saturated hydrocarbons, branched saturated hydrocarbons, and derivatives thereof; naphthenic mineral oils; and synthetic oils such as hydrogenated polyisobutylene, polyisobutylene, and polybutene. Among these, paraffinic mineral oils are preferred from the viewpoint of compatibility with the elastomer component, and paraffinic mineral oils with a small number of aromatic carbon atoms are more preferred. Furthermore, from the viewpoint of ease of handling, those that are liquid at room temperature are preferred.

[0065] From the viewpoint of heat resistance and handling, the dynamic viscosity of component (C) at 37.8°C, measured in accordance with JIS K2283-2000, may be 20 to 1000 cSt or 50 to 500 cSt. Also from the viewpoint of handling, the pour point of component (C), measured in accordance with JIS K2269-1987, may be -10 to -25°C. Furthermore, from the viewpoint of safety, the flash point (COC) of component (C), measured in accordance with JIS K2265-2007, may be 170 to 300°C.

[0066] The amount of component (C) can be 1 to 400 parts by mass, 10 to 250 parts by mass, or 40 to 180 parts by mass per 100 parts by mass of component (A), from the viewpoint of balancing flexibility and mechanical properties.

[0067] [Lubricant (Component (D))] Various compounds that are understood by those skilled in the art to function as lubricants in this field can be used as the lubricant (component (D)). The use of component (D) is advantageous in terms of mold release properties and suppression of friction on the paper surface.

[0068] Examples of the above component (D) include silicone compounds, fluorine compounds, surfactants, etc., and silicone compounds are preferred from the viewpoint of suppressing friction on the paper surface.

[0069] As the above-mentioned silicone-based compounds, silicone oil, silicone gum, etc., can be used. Among these, high molecular weight compounds are preferred from the viewpoint of heat resistance, bleed resistance, and friction suppression on the paper surface. However, since high molecular weight silicone-based compounds are generally high-viscosity liquids or gums and tend to have poor handling properties, blends with resins or copolymers with resins are preferable for use. The resin used here is selected considering compatibility with other components constituting the friction body, especially component (A), but generally olefin resins such as polyethylene and polypropylene are preferred.

[0070] As the fluorine-based compound mentioned above, polyvinylidene fluoride, polyvinyl fluoride, etc., can be used. Among these, polyvinylidene fluoride is preferred from the viewpoint of suppressing friction on the paper surface.

[0071] Any of the above-mentioned surfactants can be used: anionic, cationic, or nonionic.

[0072] The amount of component (D) can be 0.1 to 30 parts by mass, 0.5 to 20 parts by mass, or 1 to 10 parts by mass per 100 parts by mass of component (A), from the viewpoint of suppressing friction on the paper surface.

[0073] The content of component (D) in the friction body (in a preferred embodiment, the content of silicone oil, or in another preferred embodiment, the content of a fluorine-based compound) is preferably 0.1 to 3.0% by mass. From the viewpoint of suppressing friction on the paper surface, the above content may be 0.1% by mass or more, 0.3% by mass or more, or 0.5% by mass or more, and from the viewpoint of obtaining good erasing performance and resistance to paper surface staining, it may be 3.0% by mass or less, 2.5% by mass or less, or 2.0% by mass or less.

[0074] [Crosslinking agent (component (E))] Various compounds that are understood by those skilled in the art to function as crosslinking agents in this field can be used as the crosslinking agent (component (E)). In the friction body, component (E) is primarily formulated for the purpose of crosslinking component (A). The use of component (E) is advantageous in reducing the 120°C compression set and increasing the Shore A hardness.

[0075] Examples of the above component (E) include organic peroxides and phenolic compounds, with organic peroxides being preferred from the viewpoint of wear resistance.

[0076] The above organic peroxide is a compound in which one or two hydrogen atoms of hydrogen peroxide are replaced with a free organic group. Because the organic peroxide has a peroxide bond within its molecule, it generates radicals when the friction body is manufactured (for example, when the material composition is melt-kneaded), and these radicals react in a chain reaction to crosslink component (A).

[0077] Examples of the above-mentioned organic peroxides include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexine-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butylcumyl peroxide. Among these, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane and 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyn-3 are preferred from the viewpoint of low odor, low coloration, and scorch safety.

[0078] Furthermore, when using an organic peroxide as component (E), it is preferable to also use the crosslinking aid (component (F)) described later. By using component (F), a uniform and efficient crosslinking reaction can be achieved.

[0079] Of the above phenolic compounds, resol resins are preferred from the viewpoint that they are usually liquid. Resol resins are produced by the condensation of alkyl-substituted phenols or unsubstituted phenols with an aldehyde (preferably formaldehyde) in an alkaline medium, or by the condensation of difunctional phenol dialcohols. The alkyl substituent portion of alkyl-substituted phenols typically has 1 to 10 carbon atoms. Dimethylolphenol or phenol resins substituted with an alkyl group having 1 to 10 carbon atoms at the p-position are preferred.

[0080] Among the phenolic compounds mentioned above, alkylphenol formaldehyde resin, methylolated alkylphenol resin, and brominated alkylphenol resin are preferred. From an environmental perspective, it is preferable that the resin is not brominated, but it may also be a resin in which the terminal hydroxyl groups are brominated. Alkylphenol formaldehyde resin is particularly preferred.

[0081] The amount of component (E) can be 0.01 to 20 parts by mass, 0.1 to 10 parts by mass, or 0.5 to 5 parts by mass per 100 parts by mass of component (A). It is preferable that the amount is above the lower limit above in that the crosslinking reaction proceeds well, while it is preferable that the amount is below the upper limit above in that crosslinking does not proceed too far and good moldability is maintained.

[0082] [Crosslinking agent (Component (F))] Various compounds that are understood by those skilled in the art to function as crosslinking aids or crosslinking accelerators in this field can be used as crosslinking aids (component (F)). Examples of the above component (F) include polyfunctional methacrylate compounds such as triallyl cyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate with 9 to 14 repeating units of ethylene glycol, trimethylolpropane trimethacrylate, allyl methacrylate, 2-methyl-1,8-octanediol dimethacrylate, and 1,9-nonanediol dimethacrylate; polyfunctional acrylate compounds such as polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and propylene glycol diacrylate; and polyfunctional vinyl compounds such as vinyl butyrate or vinyl stearate. One or more of these can be used as component (F).

[0083] Among the above components (F), polyfunctional acrylate compounds and polyfunctional methacrylate compounds are preferred, with triallyl cyanurate, triethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate being particularly preferred. These compounds are easy to handle, have an organic peroxide solubilizing effect, and act as dispersing aids for organic peroxides, so when used in combination with organic peroxides, they can make crosslinking more uniform and effective.

[0084] The amount of component (F) can be 0.01 to 50 parts by mass, 0.5 to 30 parts by mass, or 1 to 20 parts by mass per 100 parts by mass of component (A). It is preferable that the amount is above the lower limit above in that the crosslinking reaction proceeds well, while it is preferable that the amount is below the upper limit above in that the crosslinking does not proceed too far and the dispersion of the crosslinked material in the friction body is well maintained.

[0085] [Coloring agent (ingredient (G))] As the coloring agent (component (G)), various compounds that are understood by those skilled in the art to function as coloring agents in this field can be used. Inorganic pigments, organic pigments, etc., are preferred as component (G).

[0086] (Pen nib 20) As shown in Figures 1 to 6 and Figures 9(a) to (f), 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 an inclined (knife-cut) shape on the upper side of the rectangular base so that it is at an angle that makes writing easier. The inclination of this writing section 25 can be set as appropriate according to the ease of use for writing, etc. Furthermore, as shown in Figure 3(a), the writing section 25 has a thick line width W, preferably a line width W of 1 mm or more, and more preferably a line width W of 2 mm or more. In this embodiment, the line width W is 4 mm. 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.

[0087] The ink guide section 26 is in the shape of a thin plate and has an inclined portion 26a (inclination angle: θ) 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 inclination angle θ is an inclination that efficiently introduces the ink from the ink storage body 17 into the ink guide section 26. 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 exhibit the effects of this disclosure, 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.

[0088] The fibers that make up the fabric can be obtained by known methods such as melt spinning, dry spinning, wet spinning, direct spinning (meltblown, spunbond, electrostatic spinning, etc.), a method of extracting fine fibers by adsorbing one or more resin components from composite fibers, and a method of obtaining divided fibers by beating the fibers. 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.

[0089] 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.

[0090] 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.

[0091] 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, as shown in Figures 3(b) and 6. From the point of supplying a suitable amount of ink and productivity, the lower limit is preferably 0.5 mm or more. 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 portion 26a1 of the ink guide portion 26 is inserted into the front end of the ink storage body 17, and the front end portion 26A is in contact with the writing portion 25 via the holder 30. In this configuration, the contact portion 27 between the front end portion 26b of the ink guide portion 26 and the rear end surface portion 25A of the writing portion 25 allows the ink in the ink storage body 17 to be efficiently supplied to the writing portion 25 in a suitable amount by capillary action through the ink guide portion 26 and the contact portion 27.

[0092] (Holding body 30) As shown in Figures 1 to 6 and Figures 9(a) to (j), the holder 30 fixes the writing section 25 and the ink guide section 26, and its rear end is 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 abuts against 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.

[0093] 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 26A of the ink guide section 26. This increases the fixing force by pressing the tip side 26A 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, or the like, and is fixed to the writing portion 25. In this writing instrument A, the writing portion 25 is fixed (attached) to the holder 30 by fitting and holding the writing portion 25 between the front holding portions 34a and 34b. 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.

[0094] The ink guide portion 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 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 and mounting surfaces 36a and 36b of the holder 30, and the ink guide portion 26 and the writing portion 25 are pressed together and fixed in place. As a result, ink from the ink storage body 17 is supplied well to the writing portion 25 via the ink guide portion 26 and the contact portion 27.

[0095] 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 holder 30 may be constructed using one of the above materials, or two or more materials for further improvements in durability, visibility, etc., and can be molded by various molding methods such as injection molding and blow molding.

[0096] In this embodiment, as shown in Figure 3(b), the visible portion 33 of the holder 30 has a minimum width X 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 X of the visible portion 33 of the holder 30 expands from the front end to the rear end, and the minimum width X 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 X 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 X, i.e., 7.4 mm or more. As shown in Figure 10(a), for example, at a writing angle of 60°, the 3.7 mm wide characters fit within the visible portion 33 even when viewed from above (3.7 mm / cos 60° = 7.4 mm). In order to set the minimum width X of the visible portion 33 to 3.7 mm or more and its length Y to 7.4 mm or more, it is necessary to configure (specify) the structure, shape, etc. of each component of the pen tip 20 (writing portion 25, ink guidance portion 26, holder 30) as described above and combine them appropriately, which is the first way to achieve this.

[0097] 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 fixed in place by being fitted and held in the concave retaining groove 36 and mounting surfaces 36a and 36b. Moreover, for reasons of efficient assembly and productivity, its side surface is not covered by a structure that covers the entire ink guide section 26, but is open to the outside air. As a result, the overall width and length, including the width t of the ink guide section 26, is kept to the minimum necessary, and the width X of the visible portion 33 is maximized.

[0098] 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.

[0099] Next, the pen tip 40 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 of the pen tip 40 (ink reservoir side) is inserted into the ink reservoir 17, and ink from the ink reservoir 17 is supplied to the pen tip 40 by capillary action. The pen tip 40 is made of a porous material, and for example, it is made of a parallel fiber bundle consisting 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, or a fiber core made by processing fiber bundles such as felt or resin processing these fiber bundles, or a porous body (sintered core) made by sintering plastic powder such as thermoplastic resin such as polyolefin resin, acrylic resin, polyester resin, polyamide resin, and polyurethane resin. Preferred pen tip 40s include fiber bundle cores, fiber cores, sintered cores, felt cores, sponge cores, and inorganic porous cores, with fiber cores being particularly preferred from the viewpoint of deformability and productivity. Furthermore, the porosity, size, hardness, etc. of the pen tip 40 used will vary depending on the type of ink, the type of writing instrument, etc., and for example, a porosity of 30 to 60% is preferred. In this disclosure, "porosity" is calculated as follows. First, a writing lead having a known mass and apparent volume is immersed in water and, after being thoroughly soaked in water, the mass is measured when it is removed from the water. From the measured mass, the volume of water soaked into the writing lead is derived. Assuming that this volume of water is the same as the pore volume of the writing lead, the porosity is calculated from the following formula. Porosity (unit: %) = (volume of water) / (apparent volume of 20 or 40 nib) × 100

[0100] In the writing instrument A configured in this way, an ink-absorbing body 17 containing writing ink is inserted and held inside the writing instrument body 10. The tip end is fixed to the pen tip 20 (writing section 25, ink guide 26, holder 30) via the front barrel 16 by sequential fitting, and the other end is fixed to the holder 45 to which the pen tip 40 is attached by fitting. In this way, a twin-type writing instrument A can be easily manufactured. The ink absorbed in the ink-absorbing body 17 is efficiently supplied by capillary action to the writing section 25 and the pen tip 40 via a thin plate-shaped ink guide section 26 at the pen tip 20, and is used for writing.

[0101] 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 1 to 6, the pen tip 20 of this writing instrument A has a visible part (window) 33 that allows the writing direction to be seen. The ink in the ink storage body 17 reaches the writing part 25 by the capillary force of the ink guide part 26 and is used for writing. When writing, looking at the visible side through the visible part (window) 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.

[0102] The pen tip in the above embodiment comprises at least a writing section 25, 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 (X) 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. To explain in more detail how the configuration 1 described above maximizes the effective area of ​​the visible portion 33, as shown in Figure 10(a), the visible portion 33 becomes significantly wider than that of conventional models. For example, even when viewing a 10.5pt (size 5) character from above at a writing angle of 60°, the character A can be clearly seen within the visible portion 33.

[0103] 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 indicated by the ink guide section 26. 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 characters. 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. As shown in Figure 10(b), the wider visible area 33 makes the writing direction even clearer, further improving the ease of writing.

[0104] 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 this disclosure 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 ends of the writing section 25 (26A and 25A) to come into contact (with the contact section 27) (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 disclosure. Furthermore, since this writing instrument A has good ink flow, even when writing at a high speed with the pen tip 20 moving, the ink supply keeps up well, resulting in a writing instrument that does not produce smudging or other issues with the writing.

[0105] Furthermore, writing instruments B to F of the second to sixth embodiments, which are other examples of embodiments of this disclosure, will be described in more detail with reference to Figures 11 to 30. Figures 11 to 30 are drawings of the second to sixth embodiments, which are other examples of embodiments of the present disclosure, showing each writing instrument and its pen tip portion with the cap removed. The writing instruments B to F of the second to sixth embodiments shown in Figures 11 to 30 are forms in which the pen tip portion of the writing instrument A, which is the first embodiment shown in Figures 1 to 10, has been slightly modified, specifically the shape of the opening at the tip of the front barrel 16, the shape of the flange portion 32 of the holder 30 attached to the opening of the front barrel 16, the shape and structure of the writing portion 25 and ink guide portion 26 which become the pen tip 20, and the shape and structure of the visible portion 33a of the holder 30, as well as forms that further combine these modified forms. The following details the changes made to each of the writing instruments B through F, which represent each embodiment.

[0106] Figures 11 to 14 are drawings of the writing instrument B and its nib portion according to the second embodiment of the present disclosure. Figures 11(a) to (g) are drawings corresponding to Figure 2 with the cap removed. Figures 12(a) and (b) are perspective views of the nib of writing instrument B from the front and rear. Figures 13(a) and (b) are perspective views of the nib of Figure 12 rotated 180° and viewed from the front and rear. Figures 14(a) to (g) are drawings of the nib portion of writing instrument B.

[0107] The writing instrument B, which is the second embodiment of this disclosure, differs from the writing instrument A of the first embodiment in that the writing part is vertical rather than inclined (knife-cut) (vertical writing part 25a), the L-shaped writing part 25a and the ink guide part 26 are formed integrally as a single part rather than as two separate parts, the visible part of the holder 30 is cut into a thin plate shape (concave shape) to form a smooth visible surface, the visible part 33a, and the ink guide part 26 is positioned on the back side (upper side) rather than the front side when writing (the L-shape faces upward).

[0108] The pen tip of the writing instrument B in this embodiment comprises at least a writing section 25a, a holder 30 having a visible section 33a which is a thin, smooth, plate-like surface, and an ink guide section 26 which guides ink from the writing instrument body 10 to the writing section 25a. The writing section 25a and the ink guide section 26 are integrally formed. In this embodiment as well, similar to the writing instrument A described above, the minimum width of the visible section 33a is 3.7 mm or more, and the length of the visible section 33 is 7.4 mm or more (configuration 1). Since the visible section 33a of the holder 30 is a thin, plate-like (concave) smooth, viewable surface, it is possible to maximize the effective area of ​​the visible section 33a that allows the writing direction to be seen, as well as achieve a high degree of ease of writing. Furthermore, since the width of the ink guidance section 26 is configured to be 1.2 mm or less when viewed from the vertical surface of the visible section 33a, similar to the writing instrument A described above (configuration 3), the area of ​​the visible section 33a can be further maximized, and the effects of this disclosure can be achieved to an even higher degree.

[0109] Figures 15 to 18 are drawings of the writing instrument C and its nib portion according to the third embodiment of the present disclosure. Figures 15(a) to 15(f) are drawings corresponding to Figures 2 and 11 with the cap removed. Figures 16(a) and 16(b) are perspective views of the nib of the writing instrument C from the front and rear. Figures 17(a) and 17(b) are perspective views of the nib of Figure 16 rotated 180° and viewed from the front and rear. Figures 18(a) to 18(g) are drawings of the nib portion of the writing instrument C.

[0110] The writing instrument C, which is a third embodiment of the present disclosure, differs from the writing instrument A of the first embodiment in that the opening surface on the tip side of the front barrel 16 is vertical rather than inclined (vertical opening 16i), the contact surface of the flange portion 32 of the holder 30 attached to the vertical opening 16i of the front barrel 16 is also a vertical contact surface, the L-shaped writing portion 25 and ink guide portion 26 are formed integrally as a single part rather than as two parts, the visible portion of the holder 30 is cut into a thin plate shape (concave shape) to become a smooth visible surface visible portion 33a, and the ink guide portion 26 is positioned on the back side (upper side) rather than the front side when writing (the L-shape faces upward).

[0111] The pen tip of the writing instrument C in this embodiment has at least a writing section 25, a holder 30 having a visible section 33a which is a thin, plate-shaped, smooth viewing surface, and an ink guiding section 26 which guides ink from the writing instrument body 10 to the writing section. The writing section 25 and the ink guiding section 26 are integrally formed, and the opening 16i at the tip of the front barrel 16 is vertical. In this form as well, similar to the writing instrument A described above, the minimum width of the visible section 33a is 3.7 mm or more, and the length of the visible section 33 is 7.4 mm or more (configuration 1). Since the visible section 33a of the holder 30 is a thin, plate-shaped (concave) smooth viewing surface, it is possible to maximize the effective area of ​​the visible section 33 which allows the writing direction to be seen, as well as improve visibility and ease of writing. Furthermore, since the width of the ink guide section 26 is configured to be 1.2 mm or less when viewed from the vertical surface of the visible section 33a, similar to the writing instrument A described above (configuration 3), the area of ​​the visible section 33a can be further maximized, and the effects of this disclosure can be achieved to an even higher degree.

[0112] Figures 19 to 22 are drawings of the writing instrument D and its nib portion according to the fourth embodiment of this disclosure. Figures 19(a) to (g) are drawings corresponding to Figures 2, 11, and 15 with the cap removed. Figures 20(a) and (b) are perspective views of the nib of the writing instrument D from the front and rear. Figures 21(a) and (b) are perspective views of the nib of Figure 20 rotated 180° and viewed from the front and rear. Figures 22(a) to (g) are drawings of the nib portion of the writing instrument D. The fourth embodiment of the present disclosure, the writing instrument D, differs from the writing instrument A of the first embodiment in that the L-shaped writing section 25 and the ink guide section 26 are formed integrally as a single part rather than being two separate parts, and the ink guide section 26 is positioned on the back (upper) side rather than the front side when writing (the L-shape faces upward).

[0113] The pen tip of the writing instrument D in this embodiment has at least a writing section 25, a holder 30 having a visible section 33 which is a thin, smooth, plate-like surface, and an ink guide section 26 which guides ink from the writing instrument body 10 to the writing section. The writing section 25 and the ink guide section 26 are integrally formed. In this embodiment as well, similar to the writing instrument A described above, the minimum width of the visible section 33 is 3.7 mm or more, and the length of the visible section 33 is 7.4 mm or more (configuration 1). This configuration makes it possible to maximize the effective area of ​​the visible section 33 which allows the writing direction to be seen, as well as to achieve a high degree of ease of writing. Furthermore, since the width of the ink guide section 26 is set to 1.2 mm or less when viewed from the vertical surface of the visible section 33, similar to the writing instrument A described above (configuration 3), the area of ​​the visible section 33 can be further maximized, and the effects of this disclosure can be achieved to an even higher degree.

[0114] Figures 23 to 26 are drawings of the writing instrument E and its nib portion according to the fifth embodiment of this disclosure. Figures 23(a) to (g) are drawings corresponding to Figures 2, 11, 15, and 19 with the cap removed. Figures 24(a) and (b) are perspective views of the nib of the writing instrument E viewed from the front and rear. Figures 25(a) and (b) are perspective views of the nib of Figure 24 rotated 180° and viewed from the front and rear. Figures 26(a) to (g) are drawings of the nib portion of the writing instrument E. The fifth embodiment of the writing instrument E of this disclosure differs from the writing instrument A of the first embodiment in that the L-shaped writing section 25 and the ink guide section 26 are formed integrally as a single part rather than as two separate parts, and the visible portion 33a of the holder 30 is cut into a thin plate shape (concave shape) to create a smooth viewing surface.

[0115] The pen tip of the writing instrument E in this embodiment comprises at least a writing section 25, a holder 30 having a visible section 33a which is a thin, smooth, plate-like surface, and an ink guide section 26 which guides ink from the writing instrument body 10 to the writing section. The writing section 25 and the ink guide section 26 are integrally formed. In this embodiment as well, similar to the writing instrument A described above, the minimum width of the visible section 33a is 3.7 mm or more, and the length of the visible section 33 is 7.4 mm or more (configuration 1). Since the visible section 33a of the holder 30 is a thin, plate-like (concave) smooth, viewable surface, it is possible to maximize the effective area of ​​the visible section 33 which allows the writing direction to be seen, as well as achieve a high degree of ease of writing. Furthermore, similar to the writing instrument A described above, the ink guide section 26 is positioned on the side facing the user during writing. That is, the ink guide section 26, which becomes integrated with the writing section 25 when fixed to the holder 30, is positioned 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) (Configuration 2). As a result, even when a natural writing angle is applied, the visibility of the visible section 33 is further improved regardless of the direction of writing. This allows for a high degree of balance between maximizing the effective area of ​​the visible section 33, which allows the user to see the writing direction, and ensuring ease of writing. Furthermore, since the width of the ink guidance section 26 is set to 1.2 mm or less when viewed from the vertical surface of the visible section 33, similar to the writing instrument A described above (configuration 3), the area of ​​the visible section 33 can be further maximized, and the effects of this disclosure can be achieved to an even higher degree.

[0116] Figures 27 to 30 are drawings of the writing instrument F and its nib portion according to the sixth embodiment of the present disclosure. Figures 27(a) to (f) are drawings corresponding to Figures 2, 11, 15, 19, and 23 with the cap removed. Figures 28(a) and (b) are perspective views of the nib of the writing instrument F from the front and rear. Figures 29(a) and (b) are perspective views of the nib of Figure 28 rotated 180° and viewed from the front and rear. Figures 30(a) to (g) are drawings of the nib portion of the writing instrument F. The sixth embodiment of the writing instrument F of this disclosure differs from the writing instrument A of the first embodiment in that the opening at the tip of the front barrel 16 is vertical rather than inclined (vertical opening 16i), the writing section 25 is vertical rather than inclined (knife-cut) (vertical writing section 25a), and the L-shaped writing section 25 and the ink guide section 26 are formed integrally as a single part rather than as two separate parts.

[0117] The pen tip of the writing instrument F in this embodiment has at least a writing section 25, 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, with the writing section 25 and the ink guide section 26 being integrally formed. In this embodiment as well, similar to the writing instrument A described above, the minimum width of the visible section 33 is 3.7 mm or more, and the length of the visible section 33 is 7.4 mm or more (configuration 1), thus achieving a high degree of balance between maximizing the effective area of ​​the visible section 33 that allows the writing direction to be seen, ease of viewing, and ease of writing. Furthermore, similar to the writing instrument A described above, the ink guide section 26 is positioned on the side facing the user during writing. That is, the ink guide section 26, which becomes integrated with the writing section 25 when fixed to the holder 30, is positioned 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) (Configuration 2). As a result, even when a natural writing angle is applied, the visibility of the visible section 33 is further improved regardless of the direction of writing. This allows for a high degree of balance between maximizing the effective area of ​​the visible section 33, which allows the user to see the writing direction, and ensuring ease of writing. Furthermore, since the opening 16i at the tip of the front barrel 16 is vertical, and the writing section 25a is also vertical, the ink guide section 26, which is integrated with the writing section 25a, can be positioned towards the user during writing (on the side where the pen tip 20 is at an obtuse angle to the ink guide section 26) as described above. By changing the direction of the pen tip (rotating it 180°), the ink guide section 26 can be positioned towards the user during writing (the L-shape faces downwards). Furthermore, since the width of the ink guidance section 26 is set to 1.2 mm or less when viewed from the vertical surface of the visible section 33, similar to the writing instrument A described above (configuration 3), the area of ​​the visible section 33 can be further maximized, and the effects of this disclosure can be achieved to an even higher degree.

[0118] The writing instruments described herein may be further modified in various ways without being limited to the embodiments described above, as long as the technical concept of the disclosure is not altered. For example, in the above embodiment, each writing instrument is configured with either configuration 1 or configuration 2, but each writing instrument may also be configured with a combination of configurations 1 and 2, or with a combination of configuration 1 or 2 and configuration 3 and / or configuration 4. Furthermore, in the above embodiment, the writing instrument of configuration 1 is configured such that the ink guide portion 26 is on one side of the visible portion 33 as a preferred embodiment. However, even in the configuration of configuration 1, if there are two ink guide portions 26 on the upper and lower surfaces of the visible portion 33 (a U-shaped or U-shaped configuration with two ink guide portions 26, 26, which are integral or separate components, on both sides of the writing portion 25, the ink guide portion may cross the characters in the direction of writing (marking)), the effects of this disclosure can also be achieved in a configuration of the visible portion 33 with an unprecedentedly wide range, that is, a configuration in which the minimum width (X) of the visible portion 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.

[0119] The porosity of the writing section 25 is preferably within the following range. The porosity is preferably 30-80%, and more preferably 40-70%.

[0120] Although the writing instruments A to F of the above embodiments are shown as twin-type writing instruments, the pen tip 40 may be omitted (the barrel may be a bottomed cylindrical barrel) and a single-type writing instrument equipped with a pen tip 20 may be used, or a writing instrument in which the pen tip 20 extends and retracts by a click mechanism may be used. In the writing instruments A to F 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 writing instruments A to F of the above embodiments were described using ink for writing instruments (water-based ink, oil-based ink, thermochromic ink), other liquid substances such as liquid cosmetics, liquid pharmaceuticals, coating solutions, and correction fluids may also be used. [Examples]

[0121] Next, the present disclosure will be further described by examples, but will not be limited to the following examples.

[0122] [Example 1] A writing instrument with a nib conforming to the configuration and Figures 1 to 10 below, and writing ink with the composition described below were used. The dimensions of the nib were as shown below.

[0123] [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, W=5.5 mm Ink guide section 26: PET fiber core, width: 2mm, length: 20mm, thickness t: 0.8mm 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): X=3.8mm (maximum 4.5mm) × Y=8mm × width (thickness) 2.5mm

[0124] Ink absorbent 17: PET fiber bundle, 85% porosity, φ6 × 80 mm 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-butadiene-styrene (SEBS) selected from the group consisting of these styrene-based elastomers.

[0125] (Writing instrument ink composition: Ink color: Fluorescent yellow) The following ink composition (total 100% by mass) was used as the ink for the writing instrument. Microcapsule pigment 25.0% by mass Hydroxyethylcellulose 0.4% by mass Glycerin 5.0% by mass Modified silicone-based defoaming agent 0.1% by mass Preservative 1.0% by mass pH adjuster (10% diluted phosphoric acid solution) 0.15% by mass Deionized water remaining

[0126] (Preparation of microcapsule pigments, ink pH, viscosity, surface tension, etc.) A thermochromic color memory composition consisting of 4.0 parts of 4-[2,6-bis(2-ethoxyphenyl)-4-pyridyl]-N,N-dimethylbenzeneamine as an electron-donating color-developing organic compound component, 10.0 parts of 2,2-bis(4′-hydroxyphenyl)hexafluoropropane as an electron-accepting compound component, and 50.0 parts of 4-benzyloxyphenylethyl capric acid as a reaction medium component that determines the temperature at which the color reaction occurs was uniformly heated and dissolved. A solution was mixed with 30.0 parts of aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a co-solvent. This solution was emulsified and dispersed in an 8% aqueous polyvinyl alcohol solution to form fine droplets, and after stirring at 70°C for about 1 hour, 2.5 parts of a water-soluble aliphatic-modified amine were added, and stirring was continued for a further 6 hours to obtain a reversible thermochromic microcapsule pigment suspension. The suspension was centrifuged to isolate the reversible thermochromic microcapsule pigment. The average particle size of the microcapsule pigment is 2.0 μm, and it is colorless at temperatures above 50°C and changes to yellow at temperatures below -10°C. pH: 5.4 Viscosity (25°C): 3.0 mPa·s (Complete viscometer, TOKIMEC TV-20) Surface tension (25°C): 33 mN / m (Automatic surface tension meter, Kyowa Interface Science Co., Ltd., DY-300)

[0127] In this writing instrument using the pen tip 20 of Example 1, which conforms to Figures 1 to 10, ink from the ink storage body 17 is guided to the writing section 25 by a thin, open, flowable ink guide section 26. The writing section 25 is made of a resin sintered core, and the ink guide section 26 is made of a fiber bundle core. As a result, the capillary force is strong relative to the porosity, and the thickness can be made extremely thin, resulting in good ink flow. There is no need to design the ink guide section to be thick, and the minimum width X of the visible section 33 is 3.7 mm or more, and its length Y is 7.4 mm or more. Therefore, it is possible to maximize the effective area of ​​the visible section 33, which allows the writing direction to be seen, and achieve a high level of readability 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.

[0128] 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. [Industrial applicability]

[0129] The writing instrument of this embodiment can be suitably applied as a type of writing instrument called an underline pen, paint marker, oil-based marker, or water-based marker. [Explanation of symbols]

[0130] 10 Writing instrument body 11 Rear axle 16 front axis 17 Ink absorber 20 nibs 25 Writing section 26 Ink guide section 30 Holder 33 Visible part

Claims

1. A writing instrument comprising a pen tip having a visible portion that guides ink supplied from the writing instrument body and allows the writing direction to be visually confirmed, wherein the pen tip comprises at least a writing portion, a holder having a visible portion, and an ink guiding portion that guides ink from the writing instrument body to the writing portion, wherein the minimum width of the visible portion is 3.7 mm or more, and the length of the visible portion is 7.4 mm or more. A writing instrument characterized in that the ink guide portion is in the shape of a thin plate, a concave retaining groove is formed on the bottom surface of the holder for fitting and holding the ink guide portion, a plurality of ribs are formed perpendicular to the axis on the surfaces on both sides of the concave retaining groove where the writing portion and the ink guide portion come into contact, and the widthwise length of the mounting surface of the retaining groove is shorter than the widthwise length of the tip side of the ink guide portion.

2. A writing instrument comprising a pen tip having a visible portion that guides ink supplied from the writing instrument body and allows the writing direction to be visually confirmed, wherein the pen tip comprises at least a writing portion, a holder having a visible portion, and an ink guiding portion that guides ink from the writing instrument body to the writing portion, wherein the ink guiding portion is provided on the side facing the user during writing, the ink guiding portion is in the shape of a thin plate, a concave retaining groove is formed on the bottom surface of the holder for fitting and holding the ink guiding portion, a plurality of ribs are formed on both sides of the concave retaining groove in a direction perpendicular to the axis on the surface where the writing portion and the ink guiding portion come into contact, and the widthwise length of the mounting surface of the retaining groove is shorter than the widthwise length of the tip side of the ink guiding portion.

3. The writing instrument according to claim 1 or 2, characterized in that the ink guiding portion is composed of a fiber bundle core having a rectangular or elliptical cross-section, the writing portion is composed of a resin sintered body, and the ink guiding portion and the writing portion are fixed to the holder, and the ink guiding portion and the writing portion are fixed together in contact with each other as a single unit.

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