Notebook

Abstract

The present invention provides a writing instrument in which there is no discrepancy between the color of the written line and the color displayed on the pen tip, allowing users to comfortably draw lines of a color that matches the color displayed on the pen tip simply by looking at the color displayed on the pen tip. [Solution] A writing instrument A comprising a writing instrument body 1 containing an ink composition 3 and having pen tips 4 and 5 made of a fibrous material on at least one end, characterized in that the difference in refractive index between the pen tips 4 and 5 and the ink composition 3 is 1.0 or more. It is preferable that titanium dioxide is coated between the fibers of the pen tips 4 and 5 described above.

Description

Technical Field

[0001] The present invention relates to a writing instrument that can draw writing lines of a color that matches the color developed in the pen core comfortably, simply by looking at the color developed in the pen core, without any difference between the color of the writing lines actually written, etc. and the color developed in the pen core.

Background Art

[0002] Conventionally, in writing instruments such as marking pens and signature pens, generally, in order to distinguish the ink color etc. used by the user, the same color as the ink color is displayed on the cap or operating part, and the user visually recognizes that color, or judges by looking at the ink color stored or hidden in the visible writing instrument body, or further recognizes the color developed in the pen core, and the user has used a writing instrument on which the ink color desired to be used is displayed etc. based on those respective displays etc.

[0003] However, in the case of light colors such as yellow, the difference between the color of the writing lines actually written etc. and the color displayed on the writing instrument or the color developed in the pen core is small, but in the case of dark colors such as blue, gray, or green, or in the case of ink that requires light shielding properties, there are cases where it cannot be used in a visible writing instrument body. In these cases, there are problems such as too much difference between the color of the writing lines actually written etc. and the color displayed etc. on the writing instrument or the color developed in the pen core, and there are inconveniences in use.

[0004] On the other hand, in the prior art, as a technology close to the present invention, for example, 1) To provide a writing instrument in which the opposite side of the pen body, which forms the pen tip, can be easily seen, the endpoint of a line can be easily recognized, and the time when the ink is running out can also be easily recognized, a writing instrument in which writing is possible by supplying ink from the pen body to the pen tip, wherein the pen tip is made of a porous material, and ink having a refractive index difference of 0.1 or less between the porous material constituting the porous material and the ink is supplied to the porous material that forms the pen tip, so that the porous material becomes the visible part (see, for example, Patent Document 1 by the present applicant). 2) A pen tip comprising a pen nib containing an opacity material, wherein the pen nib is characterized by having a lightness (L* value) of 80 or more in the L*a*b* (CIELAB) color system, and a writing instrument equipped with this pen tip, wherein the writing instrument is equipped with dye ink or resin fine particle pigment ink containing dye, and the lightness (L* value) of the pen nib impregnated with the ink is characterized by being 30 or more (see, for example, Patent Document 2 by the present applicant). These are some of the known facts.

[0005] The above-mentioned Patent Document 1 describes a writing instrument in which ink having a refractive index difference of 0.1 or less between the porous material and the ink is supplied to a porous body that serves as the pen tip, thereby making the porous body the visible part. This differs from the present invention in terms of the problem to be solved and the technical concept (structure and its effects). Upon closer examination of the above-mentioned Patent Document 2, it is revealed that a U-shaped pen tip is attached to the circumferential surface of a holder with visibility, the brightness (L* value) of the pen tip is set to 80 or higher, and the brightness (L* value) of the pen tip when impregnated with ink is set to 30 or higher, primarily with the aim of improving the visibility of the visible part of the holder, and secondarily disclosing that there is no difference in hue between the color of the colored pen tip and the hue of the written line. However, because the difference in refractive index between the ink and the pen tip is small, the color development of the pen tip after ink impregnation may be unclear, and there is still room for improvement. Furthermore, there has been a strong desire for a writing instrument in which, simply by looking at the color developed on the pen tip, one can comfortably draw a written line of a color that matches the color developed on the pen tip. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2011-46008 (Claims, Figures 1-4) [Patent Document 2] International Publication No. 2020 / 032104 (Claims, Figure 1) [Overview of the project] [Problems that the invention aims to solve]

[0007] In view of the problems and current state of the prior art described above, the present invention aims to resolve these issues and provides a writing instrument in which there is no difference between the color of the written line and the color displayed on the pen tip, and in which, simply by looking at the color displayed on the pen tip, it is possible to comfortably draw a line of a color that matches the color displayed on the pen tip. [Means for solving the problem]

[0008] In view of the above-mentioned conventional problems, the inventors have sought to resolve them and have found that a writing instrument for the above purpose can be obtained by having ink contained within the writing instrument body and having a pen tip made of a fibrous material on at least one end, and by making the difference in refractive index between the pen tip and the ink composition greater than or equal to a predetermined value, thereby completing this disclosure.

[0009] In other words, the writing instrument of the present invention is a writing instrument in which an ink composition is contained within the writing instrument body and a pen tip made of a fibrous material is provided on at least one end, characterized in that the difference in refractive index between the pen tip and the ink composition is 1.0 or more. It is preferable that titanium dioxide is coated between the fibers of the pen tip. Furthermore, it is preferable that the pen tip has a flexible function. Furthermore, it is preferable that the pen nib be located at both ends of the barrel of the writing instrument. Furthermore, it is preferable to combine the pen refill with a ballpoint pen tip. In this invention, "refractive index" refers to the ratio of the angle at which light traveling in a straight line changes its direction of propagation at the boundary of different materials, and is correlated with the angle of light according to Snell's law. Furthermore, "the difference in refractive index between the pen nib and the ink composition is 1.0 or more" means that the difference in refractive index between the pen nib, which is composed of at least a fiber material, and the ink composition is 1.0 or more. [Effects of the Invention]

[0010] According to the present invention, there is no difference between the color of the written line and the color displayed on the pen tip, and a writing instrument is provided that allows the user to comfortably draw a line of a color that matches the color displayed on the pen tip simply by looking at the color displayed on the pen tip. The object and effect of the present invention are recognized and obtained, in particular, by using the components and combinations indicated in the claims. Both the general description above and the detailed description below are illustrative and descriptive, and do not limit the present invention as described in the claims. [Brief explanation of the drawing]

[0011] [Figure 1] This is a partial longitudinal cross-sectional view of a writing instrument showing the first embodiment. [Figure 2] (a) and (b) are explanatory diagrams illustrating the general effects of this disclosure based on the difference in refractive index between the pen nib and the ink composition. [Figure 3] These are drawings of a direct-ink type writing instrument showing the second embodiment, where (a) is a front view, (b) is a front-view longitudinal section, and (c) is a longitudinal section viewed from the direction of (b) rotated 90°. [Figure 4] Figure 3 shows the writing instrument with the cap removed, where (a) is a front view, (b) is a front view viewed from the direction of (a) rotated 90°, (c) is a longitudinal section view, and (d) is a longitudinal section viewed from the direction of (c) rotated 90°. [Figure 5]These are drawings showing an example of the writing state of the writing instrument in FIGS. 3 and 4. (a) is a perspective view of the usage state seen from one direction, and (b) is a perspective view of the usage state seen from the direction 90° unfolded from (a). [Figure 6] These are drawings showing a felt-tip pen according to the third embodiment, showing the state with the cap removed. (a) is a front view, (b) is a front view seen from the direction 90° unfolded from (a), (c) is a longitudinal sectional view, and (d) is a longitudinal sectional view seen from the direction 90° unfolded from (c). [Figure 7] These are drawings showing an example of an embodiment of another example of a felt-tip pen according to the fourth embodiment. (a) is a front view, (b) is a longitudinal sectional view in the front view, and (c) is a longitudinal sectional view seen from the direction 90° unfolded from (b). [Figure 8] These are drawings showing an example of the writing instrument with the cap removed of the writing instrument in FIG. 7. (a) is a front view, (b) is a longitudinal sectional view, and (c) is a longitudinal sectional view seen from the direction 90° unfolded from (b). [Figure 9] These are the exploded views of the components of the writing instrument in FIG. 7. [Figure 10] (a) and (b) are perspective views showing each writing part in the writing instrument in FIG. 8. [Figure 11] These are drawings showing a modified example of a felt-tip pen according to the fifth embodiment. (a) is a front view, (b) is a longitudinal sectional view, and (c) is a longitudinal sectional view seen from the direction 90° unfolded from (b). [Figure 12] These are drawings showing a modified example of a felt-tip pen according to the sixth embodiment. (a) is a front view, (b) is a longitudinal sectional view, and (c) is a longitudinal sectional view seen from the direction 90° unfolded from (b). [Figure 13] These are drawings showing the writing instrument with the cap removed of the writing instrument in FIG. 12. (a) is a front view, (b) is a longitudinal sectional view, and (c) is a longitudinal sectional view seen from the direction 90° unfolded from (b). [Figure 14] These are drawings showing an example of the writing state of the writing instrument in FIGS. 12 and 13. (a) is a perspective view of the usage state seen from one direction, and (b) is a perspective view of the usage state seen from the direction 180° unfolded from (a). [Figure 15]It is a component diagram showing the writing part of the writing instrument in FIGS. 12 to 14. (a) is a perspective view seen from the obliquely rearward direction, (b) is a perspective view seen from the rearward direction, (c) is a plan view, (d) is a right side view, (e) is a front view, (f) is a left side view, and (g) is a longitudinal sectional view.

Embodiments for Carrying out the Invention

[0012] Hereinafter, each embodiment of the writing instrument of the present invention will be described in detail with reference to the drawings. However, note that the technical scope of the present invention is not limited to the embodiments detailed below, and it should be noted that it extends to the invention described in the claims and its equivalents. In each figure, “front” regarding the writing instrument and its constituent parts indicates the direction of the tip of the writing instrument, “rear” indicates the opposite direction, “axial direction” indicates the direction of the axis penetrating from the front to the rear of the shaft cylinder, etc., and “transverse direction” indicates the direction orthogonal to the axial direction. Also, reference numerals commonly attached among the drawings represent the same configuration or member even if not particularly mentioned in the description of each drawing.

[0013] The writing instrument of the present invention is a writing instrument in which an ink composition is accommodated in the writing instrument body and a pen core made of a fiber material is provided on at least one end side, and the difference in refractive index between the pen core and the ink composition is 1.0 or more. FIG. 1 is a partial longitudinal sectional view of a writing instrument showing the first embodiment, and FIGS. 2(a) and (b) are explanatory diagrams for explaining the outline of the effect of the present invention from the difference in refractive index between the pen core and the ink. As shown in FIG. 1, the writing instrument A of the first embodiment has at least a cylindrical shaft cylinder 1 and an ink absorber (wick) 2 accommodated in the shaft cylinder 1. The ink absorber 2 has a capillary force capable of holding the entire amount of the liquid ink composition 3, and the liquid ink composition 3 is supplied to the pen cores (chisel cores) 4 and pen cores (round cores) 5 provided on both end sides of the shaft cylinder 1 for writing.

[0014] In this first embodiment, the barrel 1 is equipped with a pen tip (chisel tip) 4 and a pen tip (round tip) 5 at both ends, and the barrel 1 has a storage section in which an ink absorber 2 containing a liquid ink composition 3 is housed, making it a twin-type (double-ended) writing instrument A. The barrel 1 has a roughly tapered outer shape, with a front barrel 6 attached to one thicker end 1a and a tip 7 attached to the other thinner end 1b. A nib (chisel nib) 4 is attached to the front barrel 6, and a nib (round nib) 5 is attached to the tip 7. The nib (chisel nib) 4 and the nib (round nib) 5 are respectively fitted into both ends of the ink reservoir 2, and the liquid ink composition 3 of the ink reservoir 2 is supplied to the nib (chisel nib) 4 and the nib (round nib) 5 at both ends by capillary force, making it possible to write with either the nib (chisel nib) 4 or the nib (round nib) 5. The ink absorber 2 has capillary force capable of holding the entire amount of the liquid ink composition 3, and the pen tip (chisel tip) 4 and pen tip (round tip) 5 have stronger capillary force than the ink absorber 2. Preferably, the strength of the capillary force is such that ink absorber 2 < pen tip 5 ≤ pen tip 4.

[0015] A thick cap 8 is detachably attached to the outer circumference of the thick end 1a so as to cover the pen tip (chisel tip) 4 side. Reference numeral 8a in the figure indicates a clip. The aforementioned narrow end portion 1b is formed in a substantially cylindrical shape, and a narrow end cap 9 is detachably attached to its outer circumference on the tip side so as to cover the pen tip (round tip) 5 side.

[0016] The ink-absorbing body 2 is impregnated with a liquid ink composition such as water-based ink, oil-based ink, gel ink, or thermochromic ink, as described later. For example, it may include fiber bundles made from one or more combinations of natural fibers, animal hair fibers, polyacetal resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl resins, polycarbonate resins, polyether resins, or polyphenylene resins, processed fiber bundles such as felt, or porous bodies such as sponges, resin particles, or sintered bodies. The porosity of the ink-absorbing material 2 is preferably 50-90% in order to efficiently supply the predetermined ink to the pen nibs 4 and 5, respectively. The porosity of the ink absorber in this disclosure is calculated as follows. First, an ink absorber having a known mass and apparent volume is immersed in water, and after it has been thoroughly soaked in water, its mass is measured after it has been removed from the water. From the measured mass, the volume of water soaked into the ink absorber is derived. Assuming that this volume of water is the same as the porosity volume of the ink absorber, the porosity is calculated from the following formula (A). The porosity of the pen nib, which will be described later, is calculated in the same manner. Porosity (unit: %) = (volume of water) / (apparent volume of ink-absorbing material) × 100 …(A)

[0017] The liquid ink composition used in the present invention is not particularly limited, as long as the difference in refractive index between the ink composition and the pen nibs 4 and 5, which are made of fiber material, is 1.0 or more. This includes water-based inks, oil-based inks, gel inks, thermochromic inks, etc. However, since the ink composition used is supplied to the pen nibs 4 and 5, which are made of fiber material, it is desirable that the refractive index of the entire ink can be adjusted to a range of 1.3 to 1.6. This can be adjusted by suitably combining the colorant, solvent, and other optional components of the ink. Specifically, the components that can be used include, as solvents, water (purified water, deionized water, tap water, distilled water, pure water, etc.), ethanol, glycerin, ethylene glycol, propylene glycol monomethyl ether, methylcyclohexane, xylene, silicone, etc.

[0018] Furthermore, the colorants used in the ink can be any of the following without restriction: all dyes that dissolve or disperse in water, conventionally known inorganic and organic pigments, resin particle pigments containing pigments, pseudo-pigments obtained by coloring resin emulsions with dyes, white plastic pigments, pigments with silica or mica as a base material and a multi-layer coating of iron oxide or titanium oxide on the surface, thermochromic pigments, photochromic particles, etc. Examples of dyes include acid dyes such as eosin, foxine, water yellow #6-C, acid red, water blue #105, brilliant blue FCF, and nigrosine NB; direct dyes such as direct black 154, direct sky blue 5B, and violet BB; and basic dyes such as rhodamine and methyl violet.

[0019] Examples of inorganic pigments include azo lakes, insoluble azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, and nitroso pigments. More specifically, inorganic pigments such as carbon black, titanium black, zinc oxide, red iron oxide, aluminum, chromium oxide, iron black, cobalt blue, iron yellow, viridian, zinc sulfide, lithopone, cadmium yellow, vermilion, cadmium red, lead yellow, molybdide orange, zinc chromate, strontium chromate, white carbon, titanium oxide, clay, talc, ultramarine, precipitated barium sulfate, barite powder, calcium carbonate, lead white, navy blue, navy blue, manganese violet, aluminum powder, brass powder, etc., CI Pigment Blue 17, CI Pigment Blue 15, CI Pigment Blue 17, CI Pigment Blue 27, CI Pigment Red 5, CI Pigment Red 22, CI Pigment Red 38, CI Pigment Red 48, CI Pigment Red 49, CI Pigment Red 53, CI Pigment Red 5 Examples include 7. CI Pigment Red 81, CI Pigment Red 104, CI Pigment Red 146, CI Pigment Red 245, CI Pigment Yellow 1, CI Pigment Yellow 3, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 17, CI Pigment Yellow 34, CI Pigment Yellow 55, CI Pigment Yellow 74, CI Pigment Yellow 95, CI Pigment Yellow 166, CI Pigment Yellow 167, CI Pigment Orange 5, CI Pigment Orange 13, CI Pigment Orange 16, CI Pigment Violet 1, CI Pigment Violet 3, CI Pigment Violet 19, CI Pigment Violet 23, CI Pigment Violet 50, CI Pigment Green 7, etc.

[0020] Examples of thermochromic pigments include those produced by microencapsulating a thermochromic composition containing at least a leuco dye that functions as a color developer, a developer that has the ability to cause the leuco dye to develop color, and a color change temperature adjuster that can control the color change temperature in the color development of the leuco dye and the developer, so that the composition has a predetermined average particle size (for example, 0.2 to 3 μm). Examples of photochromic particles include photochromic particles composed of at least one selected from photochromic dyes (compounds), fluorescent dyes, etc., and a resin such as a terpene phenol resin, or photochromic particles produced by microencapsulating a photochromic composition containing at least one selected from photochromic dyes (compounds), fluorescent dyes, etc., an organic solvent, and additives such as antioxidants, light stabilizers, and sensitizers, to a predetermined average particle size (e.g., 0.2 to 3 μm).

[0021] These colorants can be used individually or in mixtures of two or more. The amount of these colorants can be increased or decreased as appropriate depending on the ink line density, and can be adjusted within a range that does not adversely affect the difference in refractive index between the pen tip and the ink composition to 1.0 or more, and can be approximately 1 to 15% by mass of the total amount of ink composition. In this invention (including the examples), the "average particle size" is the D50 value measured using a particle size analyzer [Microtrac HRA9320-X100 (manufactured by Nikkiso Co., Ltd.)]. Furthermore, within the limits that do not impair the effects of the present invention, other commonly used optional components, such as binders, dispersants, surfactants, wetting agents, and preservatives, may be included.

[0022] The pen tips 40 and 45, which form the writing portion, are made of at least a fibrous material. They are not particularly limited as long as they allow for good writing with the ink supplied from the ink reservoir 20 and the difference in refractive index between the pen tips 40 and 45 and the ink composition is 1.0 or greater. Preferably, a pen tip material with a refractive index of 1.4 to 1.6 can be selected. When a material in this range is selected, the difference in refractive index between the pen tip and the ink composition can be efficiently made 1.0 or greater. When ink is supplied, there is no difference between the color that appears on the pen tip and the color of the writing line actually written with the pen tip. By simply looking at the color that appears on the pen tip, it is possible to comfortably draw a writing line that matches the color that appears on the pen tip.

[0023] Pen nibs 4 and 5 have good ink flow and excellent ink color development, and can be made from, for example, parallel fiber bundles made from one or more combinations of 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, polyphenylene resins, etc., processed fiber bundles such as felt, or fiber cores made by resin processing these fiber bundles, or porous bodies (sintered cores) made by sintering plastic powders such as thermoplastic resins such as polyolefin resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, etc. Various forms can be selected for the pen nibs 4 and 5, such as fiber bundle nibs, sintered nibs, felt nibs, sponge nibs, and inorganic porous nibs. However, from the standpoint of writing performance and productivity, fiber bundle nibs and sintered nibs are preferable.

[0024] As shown in Figure 1, the pen nib of this embodiment consists of a chisel-shaped nib 4 and a so-called rod-shaped round nib 5. The shape of the pen nib can also be varied depending on the type of writing instrument, the size of the writing line, and other factors. The porosity of the pen nibs 4 and 5 varies depending on the type of ink and writing instrument, but it is preferable that they be between 30% and 60% in order to efficiently supply the predetermined ink to the pen nibs 4 and 5 and to further demonstrate the effects of the present invention. This porosity includes the porosity of the pen nib after titanium dioxide has been applied, as will be described later.

[0025] In this disclosure, the pen nibs 4 and 5 are not particularly limited as long as the difference in refractive index between the pen nibs 4 and 5 and the ink composition of the above composition is 1.0 or more. However, in order to further exhibit the effects of the present invention, it is preferable that titanium dioxide is coated between the fibers of the pen nibs 4 and 5. The titanium dioxide that can be used is a high refractive index material, and its average particle size is preferably 50 to 800 nm, and particularly preferably 100 to 500 nm. By setting the average particle size of titanium dioxide to 100 nm or more, color development can be improved, while keeping it below 500 nm does not impair ink flowability. The amount of titanium dioxide applied to the pen nib is not particularly limited, as long as it further improves the color development in the pen nib by fixing the titanium dioxide between the fibers of the pen nib and further exhibits the effects of the present invention. However, from the standpoint of facilitating ink flow in the pen nib and the application (fixation and compounding) of titanium dioxide to the pen nib, it is preferably 0.1 to 5% by mass of the total amount of the pen nib.

[0026] One method for fixing titanium oxide to the pen nib after molding is, for example, 1) A method of manufacturing by impregnating the molded pen tip with a processing solution containing at least titanium dioxide and a fixing resin, drying (by evaporating the solvent, etc.), and fixing it. 2) A method of manufacturing by impregnating the fibers with a treatment solution containing at least titanium dioxide and a fixing resin during the pen core molding process, and fixing them while drying (by evaporating the solvent, etc.). 3) One method involves applying a fixing resin to the molded pen tip, drying it, and then applying titanium dioxide and drying it again.

[0027] As the fixing resin used in 1) and 3) above, acrylic resin, styrene acrylic resin, urethane resin, etc. can be used, considering factors such as ink flowability and not affecting the ink. In this manufacturing method, in order to ensure good ink flowability without clogging the pen nib, a processing solution is prepared containing a fixing resin with a solid content concentration of 5 to 25% by mass and, if necessary, a solvent such as methylene chloride. The pen nib, which consists of a molded fiber bundle core, fiber core, sintered core, felt core, sponge core, inorganic porous core, etc., is impregnated into the processing solution, dried, and fixed, thereby producing a pen nib with the above-mentioned predetermined porosity and predetermined proportion of titanium oxide fixed to it.

[0028] As the fixing resin used in 2) above, acrylic resin, styrene-acrylic resin, urethane resin, etc., can be used, considering factors such as ink flowability and not affecting the ink. This manufacturing method ensures good ink flowability without clogging the pen nib, and involves preparing a treatment solution containing a fixing resin with a solid content of 5 to 25% by mass and, if necessary, a solvent such as methylene chloride, impregnating the fibers with the solution, twisting and gathering them, drying and fixing them, thereby producing a pen nib composed of a fiber bundle core, fiber core, felt core, etc., to which titanium dioxide of a predetermined porosity and predetermined proportion is fixed. The pen nibs 4 and 5 of this embodiment are composed of a fiber bundle core.

[0029] In this disclosure, by making the difference in refractive index between the pen nibs 4 and 5 of the above configuration and the ink composition of the above configuration 1.0 or more, the difference between the color of the written line and the color displayed on the pen nib is eliminated, and by simply looking at the color displayed on the pen nib, it becomes possible to draw a written line of a color that matches the color displayed on the pen nib in a pleasant manner. More preferably, the difference in refractive index is 1.05 or more, and particularly preferably 1.1 or more. If the difference in refractive index between the pen nib and the ink composition is less than 1.0, there will be a difference between the color of the written line and the color produced on the pen nib, and the effects of the present invention cannot be achieved.

[0030] Figures 2(a) and (b) are explanatory diagrams illustrating the general effects of the present disclosure based on the difference in refractive index between the pen nib and the ink composition. As shown in Figure 2(a), for example, if the refractive index of the pen nib (fiber core) is 1.58 and the refractive index of the ink composition is 1.33, the difference is 0.15. Because the difference in refractive index between the ink composition and the pen nib is small, light penetrates deep into the pen nib containing the ink, causing the color of the pen nib to become darker. As a result, there is a significant difference between the color of the written line and the color produced on the pen nib, and the effects of the present disclosure cannot be achieved. On the other hand, as shown in Figure 2(b), for example, if the refractive index of the pen nib coated with titanium dioxide (fiber nib) is 2.72 and the refractive index of the ink composition is 1.33, the difference is 1.39. Since the difference in refractive index between the ink composition and the pen nib falls within the scope of this disclosure, light is scattered on the surface of the pen nib, resulting in better color development. As a result, there is no difference between the color of the written line and the color displayed on the pen nib. By simply looking at the color displayed on the pen nib, it becomes possible to comfortably draw a written line with a color that matches the color displayed on the pen nib.

[0031] In this embodiment of writing instrument A, as shown in Figure 1, there is at least a cylindrical barrel 1 and an ink-absorbing material (cotton) 2 housed inside the barrel 1. The ink-absorbing material 2 has capillary force capable of holding the entire amount of liquid ink composition 3. The liquid ink composition 3 is supplied to the pen tip (chisel tip) 4 and pen tip (round tip) 5 provided at both ends of the barrel 1 for writing. With this writing instrument, it is easy to differentiate between drawing lines by combining the pen tip (chisel tip) 4 and the pen tip (round tip) 5. Furthermore, by making the difference in refractive index between the pen tips 4 and 5 and the ink composition 3 1.0 or more, it has been confirmed that there is no difference between the color of the written line and the color displayed on the pen tip, and that by simply looking at the color displayed on the pen tip, it is possible to draw a line of a color that matches the color displayed on the pen tip.

[0032] Although the writing instrument of the present invention is configured as described above, it is not limited to the above embodiment. As long as the difference in refractive index between the pen tip and the ink composition is 1.0 or more, so that there is no difference between the color of the written line actually written and the color developed on the pen tip, and as long as the writing instrument is configured in such a way that it is possible to draw a line of a color that matches the color developed on the pen tip simply by looking at the color developed on the pen tip, the configuration of other writing instrument components, ink supply mechanisms, etc. may be limited, and it may also be a direct-liquid type writing instrument or a valve type writing instrument equipped with a collector mechanism that directly fills the barrel (tank) which is the body of the writing instrument with ink. Furthermore, although the above embodiment shows a marking pen, it can also be suitably used as a felt-tip pen, whiteboard marker, etc.

[0033] Figures 3 to 15 illustrate and further explain writing instruments D to F, each representing a different embodiment. Figures 3 to 5 show a second embodiment of writing instrument B in which the difference in refractive index between the pen nib and the ink composition is 1.0 or greater. These figures represent a direct-ink type writing instrument in which the ink composition with the above configuration is directly mounted in the ink tank of the barrel. Figures 3(a) to 3(c) show the instrument with the cap attached, Figures 4(a) to 4(d) show the instrument with the cap removed, and Figures 5(a) and 5(b) show the writing state. The writing instrument B of this second embodiment is equipped with an ink composition having the characteristics detailed in the first embodiment, wherein the difference in refractive index between the pen nib, which is made of fiber material, and the ink composition is 1.0 or more. As shown in Figures 3(a) to (c), it has an ink tank 11 inside the barrel 10, and an ink reservoir member (collector member) 12 inside the barrel 10 that temporarily stores overflowing ink in response to pressure changes in the ink tank 11.

[0034] In other words, this writing instrument B has an ink reservoir member 12 in front of the ink tank 11. The ink reservoir member 12 is formed by a disc-shaped plate portion 13 that is positioned to unfold vertically from the rear end of a roughly cylindrical central portion and fitted into the inner circumference of the main body of the barrel 10 to create a watertight seal. Multiple thin disc-shaped thin plate portions 14 are arranged in front of this rear end plate portion 13, and ink reservoirs (lateral grooves) are formed in the gaps between these thin plate portions 14, 14, 14... by capillary action, creating an ink reservoir. The barrel 10 is molded into a cylindrical shape using a resin such as polypropylene, and functions as the body (barrel) of the writing instrument. The barrel 10 is molded to be opaque or transparent (and semi-transparent), and either can be used from an appearance or practical standpoint.

[0035] Furthermore, slit-shaped ink guide grooves (vertical grooves) 15 are formed in multiple thin plate sections 14 along the length direction of the ink reservoir member 12, leaving the central cylindrical section intact. The width of these ink guide grooves 15 is smaller than the width of any of the ink reservoir grooves 16, so that they are always filled with ink and excess ink when the pressure in the ink tank 10 rises can be immediately guided into the ink reservoir grooves 16. The ink guide grooves 15 are formed between each thin plate section 14 and are continuous with the opening grooves 20 of the plate-shaped section 13 into the ink tank 11. In the aforementioned ink reservoir member 12, the thin plate portion 14 is integrally molded to a structure in which it is connected and supported by a hollow central cylindrical portion 12a. Furthermore, a relay core 25 made of a fiber core or the like is housed in the hollow part of the inner circumference of the central cylinder 12a, and this relay core 25 supplies the aqueous ink composition for writing instruments of the present invention from the ink tank 11 to the tip of the barrel 10 and to the pen tip 30 which is integrally formed with the relay core 25.

[0036] The pen tip 30, which is integrally constructed with the intermediate core 25, may include, for example, a fiber bundle made from one or more combinations of natural fibers, animal hair fibers, polyacetal resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl resins, polycarbonate resins, polyether resins, polyphenylene resins, etc., processed fiber bundles such as felt, or porous bodies such as sponges, resin particles, or sintered bodies.

[0037] The pen tip 30 has a shape 31, 31 with semi-circular cutouts on both sides, and its tip has a writing section 32 that is angled (knife-cut) to facilitate writing. The angle of the writing section 32 is set as appropriate to suit the ease of use for writing, etc. Preferably, the writing section 32 has a line width of 1 mm or more, and more preferably, a line width of 2 mm or more. The intermediate lead 25 and the pen tip 30 do not have to be a single unit, but may be made of two parts. The shape 31 with a radially arc-shaped cutout makes it easier to obtain elastic flex during writing, and a variety of line widths can be obtained. Preferred pen nibs 30 include fiber bundle nibs, fiber nibs, sintered nibs, felt nibs, sponge nibs, and inorganic porous nibs, with fiber nibs being particularly preferred from the viewpoint of deformability and productivity. Furthermore, the porosity, size, hardness, etc. of the pen nib 30 used will vary depending on the type of writing instrument (direct liquid type, cotton type, etc.), and for example, a porosity of 30 to 70% is preferred. In the pen nib 30, it is preferable that titanium dioxide is coated between the fibers of the pen nib 30 such that the difference in refractive index between the pen nib 30 and the ink composition is 1.0 or more, similar to the first embodiment described above. The titanium dioxide that can be used is preferably 50 to 800 nm, particularly preferably 100 to 500 nm, and the amount fixed to the pen nib 30 is preferably 0.1 to 5% by mass of the total amount of the pen nib 30.

[0038] The outer circumference of the thin plate portion 14 of the ink reservoir member 12 has notches 17 that serve as air passages, which are formed in a series along the length of the ink reservoir member 12. The pen tip 30 is attached to a large-diameter cylindrical portion 12b that extends to the tip of the ink reservoir member 12. A cylindrical holder 35 is fitted between the outer circumference of the front part of the ink reservoir member 12, including the large-diameter cylindrical portion 12b, and the inner circumference of the front part of the barrel 10, preventing the ink reservoir member 12 from coming out of the barrel 10. Furthermore, an air passage is formed between the groove 12c on the outer circumference of the large-diameter cylindrical portion 12b and the inner circumference of the holder 35, and by communicating with the opening groove 20 through the air passage of the notch 17, the gas-liquid exchange of the ink tank 11 is made smooth.

[0039] When the writing instrument is not in use, the bottomed cylindrical cap 40 that covers the pen nib 30 is detachably provided so as to cover the ink reservoir member 12 mounting section of the barrel 10 up to halfway. The cap 40 has a structure in which a lid-shaped member 41 at the top is fitted onto a side cylindrical member 42, and although not shown, an air vent hole is formed in the lid-shaped member 41 from the tip to the inside. Inside the cap 40, a bowl-shaped inner cap 45 is provided, which covers the pen nib 30 and fits onto the tip of the holder 35, and is movable back and forth by a spring 46. When the cap 40 is attached to the barrel 10 in a detachable manner, the inner cap 45 first fits onto the tip of the holder 35, but in this state the cap 40 is not fully fitted onto the barrel 10. As the cap 40 is pushed further in, the spring 46 presses down on the inner cap 45, and the locking mechanism on the inside of the open end of the cap 40 fits onto the barrel and fixes it in place.

[0040] Here, as shown in Figure 3, a partition wall 18 is provided in the barrel 10 at a position closer to the center from the opposite end (rear end) of the side where the ink reservoir member 12 is located, and the space inside the barrel 10 between the plate-shaped portion 19 at the rear end of the ink reservoir member 12 and the partition wall 18 is made into an ink tank 11. Furthermore, the cylindrical rear end opening 10a behind the partition wall 18 of the shaft cylinder 10 is sealed with a tail plug 50. This tail plug 50 has a generally cylindrical shape with an open front end, a sealed rear end, and a flange 51 protruding laterally. Multiple ribs 52, 52 are formed on the side surface of the tail plug 50 to improve airtightness with the inside of the rear end of the shaft cylinder.

[0041] Furthermore, at the rear end of the shaft cylinder 10 where the tail plug 50 is fitted and sealed, an arbitrary number of vertical grooves 53 are formed on the inner circumferential surface as a structure to release air. When attempting to push the tail plug 50 into the open rear end of the shaft cylinder and fit it in place, without the vertical grooves 53, the internal pressure behind the partition wall 18 inside the shaft cylinder 10 would increase in proportion to the distance the tail plug 50 is pushed in, hindering the tail plug's advance. However, since air escapes from the vertical grooves 53, the internal pressure does not increase, and the tail plug 50 can advance smoothly and fit snugly.

[0042] In the direct-ink writing instrument B of the second embodiment configured in this way, the ink composition having the above characteristics is directly contained in the ink tank 11. As shown in Figures 3 to 5, at least a cylindrical barrel 10 and an integrated intermediate core 25 are used to supply the ink composition 11 to the pen tip 30, which is used for writing. As shown in Figures 5(a) and (b), the pen tip 30 can be used as a marking pen for writing (marking, etc.). Similar to the writing instrument A of the first embodiment described above, by making the difference in refractive index between the pen tip 30 and the ink composition 1.0 or more, there is no difference between the color of the written line and the color displayed on the pen tip. By simply looking at the color displayed on the pen tip, it is possible to draw a written line of a color that matches the color displayed on the pen tip. Furthermore, the pen tip 30, which is easily flexible during writing, allows for adjustment of the line width, enabling the creation of a variety of written lines.

[0043] Figure 6 shows drawings illustrating a third embodiment of a writing instrument in which the difference in refractive index between the pen tip and the ink composition is 1.0 or greater, and (a) to (d) are drawings showing the state with the cap removed, which has a structure similar to the cap 40 in Figure 3. Note that components similar to those of writing instrument B in Figures 3 and 4 are given the same reference numerals and their descriptions are omitted. The writing instrument C of this third embodiment houses an ink-absorbing body (cotton) 60 containing the above-described ink composition within the barrel (writing instrument body) 10a on the front side (towards the pen tip 30) of the partition wall 18. The structure is similar to that of the writing instrument B of the second embodiment described above, in which the intermediate core 25 and the pen tip 30 are integrated, that is, the ink is supplied to the pen tip 30 by capillary force through the intermediate core 25 which is attached to the insertion hole 61 of the ink-absorbing body 60. The pen tip 30 is fitted into the front opening of the barrel 10 by a joint member 65 which is fixed by fitting. The ink-absorbing body 60 is impregnated with an aqueous ink composition for writing instruments having the above-described characteristics, and includes, for example, fiber bundles made from one or more combinations of natural fibers, animal hair fibers, polyacetal resins, acrylic resins, polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl resins, polycarbonate resins, polyether resins, and polyphenylene resins, processed fiber bundles such as felt, and porous bodies such as sponges, resin particles, and sintered bodies.

[0044] In the third embodiment of the cotton-filled writing instrument C shown in Figure 6, as configured in this way, as shown in Figures 6(a) and (b), the pen tip 30 allows for writing (marking) as a marking pen. Similar to the writing instrument A of the first embodiment and the writing instrument B of the second embodiment described above, by making the difference in refractive index between the pen tip 30 and the ink composition 1.0 or more, there is no difference between the color of the written line and the color displayed on the pen tip. By simply looking at the color displayed on the pen tip, it is possible to draw a line of a color that matches the color displayed on the pen tip. Furthermore, the pen tip 30, which is easily flexible during writing, allows for adjustment of the line width during writing, enabling the creation of a variety of writing lines.

[0045] Figures 7 to 10 are drawings of a cotton-filled writing instrument D, showing a fourth embodiment in which the difference in refractive index between the pen tip and the ink composition is 1.0 or greater. Figure 7(a) is a front view, (b) is a front-view longitudinal section, (c) is a longitudinal section viewed from the direction of (b) rotated 90°, Figures 8(a) to (c) are drawings showing an example of the writing instrument of Figure 7 with the cap removed, Figure 9 is an exploded view of the parts of the writing instrument of Figure 7, and Figures 10(a) and (b) are perspective views showing each writing part of the writing instrument of Figure 8. This cotton-filled writing instrument D is a double-ended marking pen equipped with a pen tip 75 and a pen tip 90 at both ends. As shown in Figures 7 to 9, it consists of a barrel 70, a cylindrical cotton 73 that absorbs the ink composition having the above characteristics and is housed within the barrel 70, and pen tips 75 and 90 fixed to both ends of the barrel 70. 95 is a cap with an integrated clip 95a covering the pen tip 75, and 96 is a cap covering the pen tip 90.

[0046] The pen tip 75 has a knife-cut writing section 76 at the tip to improve ink flow, and the rear side of the writing section 76 has slits 77, 77... formed at predetermined intervals to provide flexibility, and the rear side (cotton side) is thicker than the writing section side, forming a porous core 78. The rear side of the porous core 78 has a triangular prism-shaped section 79 that fits into a recess 73a at the end of the cotton 73. The slits 77 make it easier to obtain elastic flexibility during writing, and a variety of line widths can be obtained. The pen tip 75 is fixed to the front end of the barrel 70 by the front barrel 80 and the refill end cap 85. The front barrel 80 is cylindrical and has a flange portion 81 with a ventilation opening 81a on its rear outer circumference, a large diameter portion 83 with a ventilation groove 82 in the axial direction, and a small diameter portion 84 on the front side of the large diameter portion 83 that holds the writing portion 76. The refill end cap 85 is attached to the large diameter portion 83 of the front barrel 80, which is fitted to the front side of the barrel 70 and holds the end (front) side of the cotton wick 73, so that the pen tip 75 with the above configuration is fixed to the front side (one end side) of the barrel 70. The rear side (the other end side) of the barrel 70 has a holding portion 71 formed therein for fixing the pen tip 90. The pen tip 90 has a thin writing section 91 and a thick section 92, and an annular fitting groove 93 is formed between the writing section 91 and the thick section 92, which fits into a fitting section 72 inside the holding section 71 of the barrel 70. The rear side of the porous core 78 has a triangular prism-shaped section 79 so as to fit into a recess 73a at the end of the cotton wick 73. The rear side of the thick section 92 of the pen tip 90 has a triangular prism-shaped section 94 so as to fit into a recess 73b at the end of the cotton wick 73.

[0047] The individual components (barrel 70, cotton wick 73, nib 75, front barrel 80, refill end cap 85, nib 90) thus form the cotton-wicked writing instrument D. The wide nib 70 is inserted from the cotton wick side towards the cap 95 side, and the refill end cap 85 receives the load on the back due to writing pressure, thereby preventing the nib from bending backward during writing.

[0048] The thin nib 90 can be prevented from bending backward (towards the cotton wick) during writing by fitting the fitting groove 93 between the thin writing section 91 and the thick section 92 with the fitting section 72 of the holding section 71 of the barrel 70. Furthermore, by providing at least one slit 77 in the radial direction of the writing portion 76 of the pen tip 75 (a total of six slits, three on the left and three on the right in the drawing), it becomes easily deformable, preventing damage to the pen tip 75 due to excessive writing pressure and providing a variety of writing experiences. In addition, by providing a refill end cap 85, the pen tip 75 is made replaceable, allowing for easy replacement when the pen tip 75 wears out. The cap 95 covering the pen tip 75 is detachably attached to the outer circumference of the thicker diameter portion 83 of the front barrel 80, and the cap 96 covering the pen tip 90 is detachably attached to the outer circumference 71a of the rear holding portion 71 of the barrel 70.

[0049] In the fourth embodiment, Figures 7 to 10, which is a double-ended cotton-filled writing instrument D equipped with a pen tip 75 and a pen tip 90 at both ends, as shown in Figures 8(a) to (c), ink is supplied from the cotton 73 by capillary force to the writing portion 76 of the pen tip 75 and the writing portion 91 of the pen tip 90, allowing it to be used as a marking pen or for writing (marking). Similar to the writing instruments A to C of the first to third embodiments described above, by making the difference in refractive index between the pen tips 75 and 90 (at least the writing portions 76 and 91 that form the pen core) and the ink composition absorbed in the cotton 73 1.0 or more, there is no difference between the color of the actual written line and the color developed on the pen core. By simply looking at the color developed on each pen core, it is possible to draw a line of a color that matches the color developed on the pen core.

[0050] Figure 11 shows a fifth embodiment of a cotton-filled writing instrument E. This writing instrument E has the same configuration as the fourth embodiment of a cotton-filled writing instrument D shown in Figures 7 to 10, and in the form shown in Figures 7 to 10, it is a double-ended writing instrument in which the thinner end of the pen nib 90 is replaced with a ballpoint pen tip 91a. The writing part (ball part) at the tip of the ballpoint pen tip 91a, which has a finer line width than the pen nib 90 of writing instrument D, allows for a variety of writing lines to be obtained. In the fifth embodiment, the cotton-filled writing instrument E shown in Figure 11, which is configured in this way, the thicker tip 75 can be used as a marking pen for writing (marking, etc.), or the thinner tip 92 can be used as a ballpoint pen tip 91a for writing. Similar to the writing instruments A to D of the first to fourth embodiments described above, in this embodiment, by making the difference in refractive index between the tip 75 (writing part 76) and the ink composition absorbed in the cotton 73 1.0 or more, there is no difference between the color of the written line and the color that is produced on the tip. As a result, by simply looking at the color produced on the tip, it is possible to comfortably write lines or draw with a ballpoint pen in a color that matches the color produced on the tip.

[0051] Figures 12 to 15 show a cotton-filled writing instrument F representing the sixth embodiment. This writing instrument F is shown in Figure This writing instrument is based on the form of Figure 7, but with a ballpoint pen tip 110 that can be attached to a pen tip 100 that does not have a slit formed therein. Note that the same structural elements as writing instrument D, including the pen tip 75 in Figure 7, will be given the same reference numerals, while different structural elements (configurations) will be given different reference numerals. As shown in Figures 15(a) to (g), the pen tip 100 has a linear opening 115 formed in the axial direction on the front outer circumference to which an annular ballpoint pen tip 110 is fixed by press-fitting or the like. The tip side of this opening 115 becomes an enlarged hole 115a to which the tip side of the ballpoint pen tip 110 is attached. This writing instrument F is a single-ended marking pen with a nib 100 at one end, the other end of the barrel 70 is a tail cap 74, and the rear part of the writing section 76 does not have a slit, and a porous section 77a is integrally connected to a large-diameter porous core 78.

[0052] By equipping the pen tip 100 with a ballpoint pen tip 110, as shown in Figure 12, the writing width can be easily switched without reversing the writing instrument by rotating the barrel circumferentially by approximately 180°. The ballpoint pen tip 110 is attached by press-fitting it into the opening 115 of the pen tip 100 via the ink guide core 111. In the sixth embodiment, the cotton-filled writing instrument F shown in Figures 12 to 15, which is configured in this way, it can be used as a marking pen for writing (marking, etc.) or as a ballpoint pen for writing. Similar to the writing instruments A to E of the first to fifth embodiments described above, in this embodiment, by making the difference in refractive index between the pen tip 100 (writing part 76) and the ink composition absorbed in the cotton 73 1.0 or more, there is no difference between the color of the written line and the color that is produced on the pen tip. As a result, by simply looking at the color produced on the pen tip, it is possible to draw a written line of a color that matches the color produced on the pen tip.

[0053] The writing instrument of the present invention is not limited to the writing instruments A to F of the above embodiments. As long as the difference in refractive index between the pen tip and the ink composition is 1.0 or more, so that there is no difference between the color of the written line and the color developed on the pen tip, and as long as the writing instrument is configured in such a way that it is possible to draw a line of a color that matches the color developed on the pen tip simply by looking at the color developed on the pen tip, the configuration of other writing instrument components, ink supply mechanisms, etc. may be limited. It may also be a direct-ink type writing instrument or a valve type writing instrument equipped with a collector mechanism that fills the ink directly into the barrel (tank) that forms the body of the writing instrument. Furthermore, although the above embodiments show a marking pen, it can also be suitably used as a felt-tip pen, whiteboard marker, etc. [Examples]

[0054] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. The following components were used for the writing instrument. Furthermore, the refractive index of the ink and pen nib used was measured using the following method.

[0055] (Writing Instrument Configuration) The writing instruments used were based on those shown in Figure 1. Shaft: Made of polypropylene, 140mm x φ10mm Ink absorbent material: PET fiber bundle batting, 85% porosity, 80mm x φ6mm Pen tip: Examples and comparative examples Ink Compositions: Examples and Comparative Examples

[0056] (Regarding the measurement of refractive index) The refractive index was measured using a digital Abbe refractometer: DR-A1 (manufactured by Atago Co., Ltd.).

[0057] (Example 1) Pen tip 40: Composed of fiber bundles, with titanium dioxide interposed between the fibers of the pen tip. Pen nib size 40: 5 x 3 x 20 mm, refractive index of resin on the pen nib surface: 1.58, refractive index of titanium dioxide attached to the pen nib surface (entire pen nib): 2.72, porosity: 60% (Example 2) Pen tip 45: Composed of a fiber bundle core, with titanium dioxide interposed between the fibers of the pen tip. Pen nib size 45: φ1.5 × 30mm, refractive index of resin on the pen nib surface: 1.58, refractive index of titanium oxide attached to the pen nib surface (entire pen nib): 2.72, porosity: 60% (Examples 1 and 2) The ink components used were formulated according to the following composition. Solvent: Purified water 95% by mass Color material: Water Blue 9 5% by mass The refractive index of the ink component was 1.38. Furthermore, the difference in refractive index between the entire pen nib and the ink components was 1.34. A writing instrument conforming to Figure 1 was fabricated using the above-mentioned pen nib, ink, etc.

[0058] (Comparative Example 1) Pen tips 40 and 45: Both pen tips are made from fiber bundles. Pen tip size 40: 5 x 3 x 20 mm, refractive index (entire pen tip): 1.58, porosity: 60% Pen tip size 45: φ1.5 x 30mm, refractive index (entire pen tip): 1.58, porosity: 60% The ink components used were formulated according to the following composition. Solvent: Purified water 95% by mass Color material: Water Blue 9 5% by mass The refractive index of the entire ink component was 1.38. Furthermore, the difference in refractive index between the entire pen nib and the ink components was 0.2. A writing instrument conforming to Figure 1 was fabricated using the above-mentioned pen nib, ink, etc.

[0059] Using each of the obtained writing instruments, the consistency between the color of the written lines and the color produced on the pen tip, as well as the writing performance, were evaluated according to the evaluation methods described below. These evaluation results are shown in Table 1 below.

[0060] (Method for evaluating the consistency between the color produced on the pen tip and the color of the written line) The hue of the pen tip and drawn lines was measured using the L*a*b* (CIELAB) color system with the following device, and ΔE was calculated and evaluated according to the following evaluation criteria. The lines are drawn in accordance with JIS S 6037, with a basis weight of 50-100 g / m². 2 The test used paper with a whiteness of 75% or higher, written on at a writing speed of 7 cm / s with a writing force of 0.5 N, and written on at an angle where the wide side of the paper was in close contact with the surface. (Measuring instrument) Micro-surface spectrophotometer VSS7700, manufactured by Nippon Denshoku Industries Co., Ltd. Evaluation criteria: A:ΔE:less than 40 B:ΔE:40 or more

[0061] [Table 1]

[0062] As is clear from the results in Table 1 above, Examples 1 to 3, which fall within the scope of the present invention, had a lower ΔE than Comparative Example 1, which falls outside the scope of the present invention, and it was found that there was no difference between the hue measured by the measuring instrument and the color produced on the pen tip. In contrast, in Comparative Example 1, not only was the ΔE higher compared to the example, but there was also a difference in hue measured by a measuring instrument compared to the color produced on the pen tip. [Industrial applicability]

[0063] This results in a writing instrument suitable for marking pens, felt-tip pens, etc., where there is no discrepancy between the color of the actual written line and the color displayed on the pen tip, allowing users to comfortably draw lines in a color that matches the color displayed on the pen tip simply by looking at the color displayed on the tip. [Explanation of symbols]

[0064] A writing instrument 1. Pen barrel (pen body) 2. Ink absorbent material (cotton padding) 3. Ink composition 4. Pen nib (chisel nib) 5 Pen tip (round tip)

Claims

1. A writing instrument in which an ink composition is contained within the body of the writing instrument, and a pen tip made of a fibrous material is provided on at least one end, characterized in that the difference in refractive index between the pen tip and the ink composition is 1.0 or more.

2. The writing instrument according to claim 1, characterized in that titanium dioxide is coated between the fibers of the pen nib.

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