JP7145193B2 - writing instrument - Google Patents

Description

The present invention relates to a writing utensil that enables writing through a writing portion from a container containing liquid writing ink.

Conventionally, as shown in Patent Document 1 and Patent Document 2, a writing instrument is disclosed which is easy for a user to use, in which a writing part is provided at the tip of a holder having visibility so that the writing direction can be visually recognized through the holder during writing. It is

However, there is a possibility that the presence of the ink passage in the holder may hinder visibility. Therefore, the applicant of the present application has disclosed a writing instrument in which the refractive index is adjusted so that the writing portion is the viewing portion (see, for example, Patent Document 3).

However, the writing instrument disclosed in Patent Literature 3 has a problem that it is difficult to combine the refractive indices of the ink and the writing lead.

JP 2012-20575 A JP 2014-50970 A Japanese Unexamined Patent Application Publication No. 2011-46008

The present invention has been made in view of the above-mentioned conventional problems, etc., and is excellent in design and stable, and it is possible to write with a writing ink such that the visible part is not hindered by the writing part or the writing ink. The purpose is to provide writing instruments.

The inventors of the present invention have attempted to solve the above-mentioned conventional problems, etc., and have provided a writing instrument having a barrel containing writing ink and a writing part attached to one end of the barrel, The writing part guides the writing ink from the barrel and has a writing body that can be written and a holding body that holds the writing body. The writing utensil having the above object can be obtained by providing the writing material on the body and setting the visible portion of the writing material to a specific value or less in the surface area of the holding body when viewed at a specific angle. have completed the present invention.

That is, the writing instrument of the present invention is a writing instrument having a barrel containing writing ink and a writing portion attached to one end of the barrel, wherein the writing portion guides the writing ink from the barrel. , a writing body that can be written, and a holding body that holds the writing body, the holding body is formed of a hard material having visibility, and the holding body is provided with the writing body on the holding body. 3. A portion of the surface area of the holder when viewed at a specific angle that allows the writing to be seen is set to 50% or less.

In addition, the thickness of the holder in a cross section perpendicular to the axial direction is 1 mm or more at the thickest part, or the ratio of the outer diameter of the writing body to the outer diameter of the holder is 1:3 or more. is preferred.
Further, it is preferable that the holding body is provided with a writing part or an ink supply part at a central part and an outer peripheral part in a radial direction.

According to the writing instrument of the present invention, the writing part guides the writing ink from the barrel and consists of a writing body that can be written and a holding body that holds the writing body, and the holding body is made of a hard material having visibility. In addition, since the visible part of the writing is made thin and visible, it is possible to make the writing part clearer while looking at the part to be written when holding the writing instrument and writing from the visibility of the holder. Excellent effect can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the writing instrument which concerns on 1st Embodiment of this invention, (a) is a front view, (b) is a longitudinal central longitudinal cross-sectional view of (a), (c) is rotated 90 degrees from (a) (d) is a central vertical sectional view in the longitudinal direction of (c). 2 is a perspective view of the writing instrument of FIG. 1; FIG. 1. It is a component drawing of the writing core of the writing instrument of FIG. 1, (a) is a perspective view, (b) is a front view, (c) is a top view. 1. It is explanatory drawing of each part of the pointing member (holding body) of the writing instrument of FIG. 1, (a) is the perspective view seen from the front, (b) is the view seen from the front, (c) is a front view, (d) ) is a central vertical cross-sectional view in the longitudinal direction of (c), (e) is a view from above, (f) is a central longitudinal cross-sectional view of (e), and (g) is a perspective view from the rear. , (h) are views seen from the rear. FIG. 4 is an explanatory diagram of a writing instrument according to a second embodiment of the present invention, in which (a) is a perspective view from the front, (b) is a front view, and (c) is a longitudinal sectional view along line CC of (b). is. It is a part view of the support member (holding body) of the writing instrument of FIG. 5, (a) is a perspective view from the front, (b) is a view from the front, (c) is a front view, (d) is a ) Vertical cross-sectional view along the DD line, (e) is a front view rotated 90 ° of (c), (f) is a longitudinal cross-sectional view along the FF line of (b), (g) It is a perspective view from behind, and (h) is a view seen from behind. It is explanatory drawing of the writing instrument which concerns on 3rd Embodiment of this invention, (a) is the figure seen from the front, (b) is the perspective view from the front, (c) is a front view, (d) is (a) 1 is a vertical cross-sectional view along line CC of FIG. It is a part view of the support member (holding body) of the writing instrument of FIG. 7, (a) is a perspective view from the front, (b) is a view seen from the front, (c) is a front view, (d) is a (b ) Vertical cross-sectional view along the DD line, (e) is a front view rotated 90 ° of (c), (f) is a longitudinal cross-sectional view along the FF line of (b), (g) It is a perspective view from behind, and (h) is a view seen from behind. It is explanatory drawing of the writing instrument which concerns on 4th Embodiment of this invention, (a) is the figure seen from the front, (b) is the perspective view from the front, (c) is a front view, (d) is (a) 1 is a vertical cross-sectional view along line DD of FIG. FIG. 10 is a part view of the support member (holding body) of the writing instrument in FIG. 9, where (a) is a perspective view from the front, (b) is a view from the front, (c) is a plan view, and (d) is a front view. , (e) is a vertical cross-sectional view along line FF in (b), (f) is a perspective view from the rear, and (g) is a view from the rear. 1A shows a path of light in a support member (holding body), FIG. 1A is a cross-sectional view of a support member according to a fourth embodiment, and FIG. (c) is an explanatory diagram of the optical path of the support member in (b), (d) is a cross-sectional view of the support member with stripes according to the fourth embodiment, (e) is (d ) is a see-through perspective view of the support member of FIG. It is explanatory drawing of the writing instrument which concerns on 5th Embodiment of this invention, (a) is the figure seen from the front, (b) is the perspective view from the front, (c) is a front view, (d) is (a) 1 is a vertical cross-sectional view along line DD of FIG. FIG. 12 is a part view of the support member (holding body) of the writing instrument of FIG. 12, (a) is a perspective view from the front, (b) is a view from the front, (c) is on the DD line of (e) (d) is a plan view, (e) is a front view, (f) is a longitudinal sectional view along the FF line of (b), (g) is a perspective view from the rear, (h) is a rear view, (i) is a cross-sectional view taken along the line II of (e), and (j) is a cross-sectional view taken along the line JJ of (e). FIG. 14 is an explanatory diagram of a modified example of the writing instrument of FIG. 13, and is an explanatory diagram of an optical path in the support member as viewed in cross section at the same location as line CC of FIG. 13(c). FIG. 11 is an explanatory diagram of a writing instrument according to a sixth embodiment of the present invention, in which (a) is a perspective view from the front, (b) is a side view, and (c) is a longitudinal sectional view along line CC of (b). is. FIG. 15 is a part view of the barrel of the writing instrument of FIG. 15, (a) is a front view, (b) is a perspective view, (c) is a side view, and (d) is a longitudinal section along the DD line of (a). It is a diagram. It is a part drawing of the support member (holding body) of the writing instrument of FIG. 16, (a) is a perspective view from the front, (b) is a view seen from the front, (c) is a side view, (d) is (b ) is a vertical cross-sectional view along line DD, (e) is a perspective view from the rear, and (f) is a vertical cross-sectional view along line CC of (c). FIG. 17 is an explanatory diagram of the transparency of the support member of the writing instrument of FIG. 16;

Hereinafter, each embodiment of the present invention will be described with reference to the drawings. In any embodiment, a cap (not shown) for protecting the writing part is detachably attached to the tip of the barrel.

[Writing implement of the first embodiment]
1 to 4 show a writing instrument according to the first embodiment of the present invention, and FIGS. 1(a) to 1(d) are explanatory diagrams of the writing instrument according to the first embodiment of the present invention.
As shown in FIGS. 1(b) and 1(d), the writing instrument A of the first embodiment has an ink occluding body 12 housed in a barrel 10 serving as the body of the writing instrument. is of the type in which is occluded. The barrel 10 is made of, for example, a thermoplastic resin, a thermosetting resin, or the like, and has a tubular shape with a closed rear end. A rib 10a for supporting the ink occluding body 12 is formed inwardly protruding from the inside of the rear portion of the shaft cylinder 10. As shown in FIG.
The writing instrument A has a structure in which an ink occluding body 12 is connected to the rear end of a writing section 14 to supply ink for the writing instrument of the ink occluding body 12 to the writing section 14 .
1A indicates the longitudinal direction (axial direction) of the barrel 10. As shown in FIG.

2 is a perspective view of the writing instrument A, FIGS. 3(a) to 3(c) are drawings of the writing body 16, and FIGS.
As shown in FIG. 2, the writing section 14 of the first embodiment has a structure in which the writing body 16 is arranged on the outer periphery of the holding body 18 and the writing body 16 is held by the holding body 18 . The writing unit 14, in which the writing element 16 is held by the holder 18, is attached to the distal end of the barrel 10 by a cylindrical front barrel 20. As shown in FIG.

In the attached state, the writing section 14 is arranged in a state in which about half of the writing body 16 and the holding body 18 protrude from the tip of the front barrel 20 and are exposed. The front barrel 20 has a cylindrical shape and is attached to the front end portion of the barrel 10 with the front end portion of the ink occluding body 12 inside. The space between the front end opening of the front barrel 20 and the writing portion 14 is closed by a flange portion 18b of the holder 18, which will be described later. being stopped. A portion (visible portion 18c) where the writing body 16 is placed around the body portion 18a of the holder 18 is transparent or translucent so that the writing target portion can be visually recognized.

The ink occlusion body 12 is impregnated with ink for writing instruments such as water-based ink and oil-based ink. Fiber bundles composed of one or a combination of two or more of resins, polyolefin resins, polyvinyl resins, polycarbonate resins, polyether resins, polyphenylene resins, processed fiber bundles such as felt, and sponges , resin particles, and porous bodies such as sintered bodies. The ink occluding body 12 is housed inside the main body of the barrel 10 . Although the rear end side of the barrel 10 is closed, it may be sealed with a tail plug formed of the same material as the barrel 10 or a different synthetic resin material.
The composition of the ink for writing instruments to be used is not particularly limited, and a suitable formulation can be set according to the use of the writing instrument. Preferably, an ink composition for writing instruments, which will be described later, is used.

1(b) and 2, the writing body 16 has a substantially U-shape so as to surround the substantially rectangular holder 18. As shown in FIG.
In the first embodiment, as shown in FIG. 3A, the writing body 16 has ink guiding portions 16a, 16a, bent portions 16b, 16b, and a writing surface portion 16c. The writing body 16 is formed of a sintered body having an ink-conducting property and having a shape obtained by bending a belt-like body having a substantially circular cross section.
The writing body 16 is composed of bent portions 16b, 16b in which the leading end sides of the ink guiding portions 16a, 16a are bent at an angle of approximately 45°, and a writing surface portion 16c formed by combining the bent portions 16b, 16b and cutting the tip end thereof. ing.

The holder 18 according to the first embodiment will be described in detail with reference to the parts diagrams of FIGS. 4(a) to 4(h).
As shown in FIGS. 1(b) and 1(d), the holder 18 fixes the writing element 16 around it and is fixed to the front end opening of the front barrel 20 of the barrel 10. As shown in FIG.
As shown in FIGS. 4(a) to 4(h), the holder 18 includes a substantially bulging body portion 18a, an annularly enlarged flange portion 18b on the front side of the body portion 18a, and a flange portion 18b. Planar visible portions 18c, 18c, which are structured to extend forward from both sides of 18b and allow the writing direction to be visually recognized, and inclined cut surfaces 18d, 18d on the upper and lower sides of the visible portions 18c, 18c and inside the front. have Further, the holding body 18 has a rear holding portion 18e provided continuously with the main body portion 18a on the rear side of the main body portion 18a. A holding groove 18f for fitting and holding the U-shaped writing body 16 is formed on the entire longitudinal outer peripheral surface of the holding body 18 composed of these parts.

A concave or convex fitting portion 18h for fitting to the inner periphery of the front barrel 20 is formed on the width direction outer peripheral surface of the main body portion 18a, and a flange portion 18b is formed on the longitudinal direction outer peripheral surface. Air circulation grooves 18i and 18j having a concave cross section for air replacement are formed on the outer peripheral surface from the rear holding portion 18e. The air circulation grooves 18i and 18j communicate with the outside air in the barrel 10. As shown in FIG. Due to this structure, the ink for the writing instrument stored in the ink occluding body 12 can be replaced with air during writing by the writing unit 14 .
Further, in the first embodiment, the large diameter portion 15a and the small diameter portion 15b, which are made of the same material as the ink occluding body 12, are integrally formed at the center of the body portion 18a of the holding body 18 in the longitudinal direction (radial direction). An ink supply body accommodating hole 18k in which a large diameter portion and a small diameter portion in which the ink supply body 15 is accommodated passes through.

The holder 18 according to the first embodiment is molded from a hard material, and is preferably made of a hard material that allows visual recognition of the writing direction, such as metal, glass, or resin that does not have rubber elasticity. A visible part 18c which is a wide smooth surface is formed in front and a body part 18a is formed in rear. Examples of resins that do not have visible rubber elasticity include styrene-isoprene resins, ionomer resins, SBR-PP blend resins, acrylic resins, nylon resins, polymethylpentene, PC (polycarbonate), transparent ABS resins, and the like. mentioned. The hard material may have a visible light transmittance that allows the user to visually recognize the direction of writing, and is preferably composed of a material having a transmittance of 50% or more.
If a material having a visible light transmittance of less than 50% is used, the target area in the writing direction may not be visually recognized effectively, which is not preferable. A material that transmits 50% or more is preferable in order to exhibit a better visual recognition function, and if the visible light transmittance is 80% or more, the material can be visually recognized even better.

The writing body 16 may be a polymer foam such as a sponge, a porous rubber body used for penetrating stamps, non-woven cloth, felt, a fiber bundle hardened with resin, or a metal, ceramic, or polymer sintered body. The outer periphery of the holder 18 is covered by fitting, bonding with an adhesive, welding, or the like. ing. In addition, a fitting groove or the like may be provided on the outer peripheral surface of the holding body 18 in order to further ensure the covering of the writing body 16 .

In the writing instrument A of the first embodiment, the mechanism for supplying ink from the ink occluding body 12 to the writing body 16 consists of the ink guiding portions 16 a and 16 a of the writing body 16 on the tip side of the ink occluding body 12 and the ink supply body 15 behind the ink supply body 15 . The ink for the writing instrument impregnated in the ink occluding body 12 is supplied to the writing surface 16c through two routes of the ink guides 16a, 16a and the ink supply body 15 by capillary force. It has a structure that By appropriately setting the capillary forces of the ink occluding body 12, the writing body 16, and the ink supply body 15, the amount of ink supplied through two routes from the ink occluding body 12 to the writing surface portion 16c of the writing body 16 can be suitably set. can be done.
In addition, the writing surface 16c on which a line is to be written can be set to a suitable line width by setting the width in the width direction to an appropriate length. It is preferable that the drawn line width is 3 mm or more.

In the first embodiment, 50% or less of the surface area of the holding body 18 where the writing body 16 is visible when viewed at a specific angle. That is, the visible portion of the writing body 16 is set to at least 50% or less in the surface area of the holding body 18, and the visible part of the writing body 16 is reduced as much as possible. When doing so, it is possible to obtain an excellent effect that the writing part can be made clearer while looking at the part to be written.
In addition, in the holder 18, the thickness of the section perpendicular to the axial direction, the thickest part, is 1 mm or more, or the ratio of the outer diameter of the writing body 16 to the outer diameter of the holder 18 is 1:3 or more. By doing so, the writing portion can be made clearer while looking at the writing target portion.
Furthermore, in the first embodiment, since the holding body 18 is provided with the writing part and the ink supply part at the center and the outer peripheral part in the radial direction, the writing surface part 16c of the writing body 16 from the ink absorbing body 12 Since ink is supplied from two directions, the amount of ink supplied is suitable without causing ink supply shortage.

[Writing instrument of the second embodiment]
Next, a writing instrument according to a second embodiment of the invention will be described.
5(a) to 5(c) show a writing instrument according to a second embodiment of the present invention, with (a) being a perspective view, (b) being a front view, and (c) being a sectional view. 5(a)-(c) are component diagrams showing a support member (corresponding to a "holder") 18B of this writing instrument.

As shown in FIG. 5(c), the rear end of a barrel 10 constituting the outer portion of the writing instrument is closed, and a writing ink occluding body 12 immersed in a fluid is placed in the inner space of the barrel 10. Contained. A front barrel 20 is attached to the tip of the barrel 10, and the front barrel 20 is a cylindrical body whose interior is tapered in a stepped manner to form a space. A brush-like writing portion 14B protrudes from the tip of the holding member 18B in the tip portion of the front barrel 20. As shown in FIG. The rear end of the writing portion 14B is inserted into and connected to the writing ink occluding body 12, and the writing portion 14B passes through the axial center of the support member 18B.
As the writing part 14B, in the case of a brush, a bundle of polybutylene terephthalate fibers can be used so as to sharpen the tip, and in the case of a pen core, nylon, polyester, and acrylic can be used as materials. Available.
Further, as shown in FIG. 5, a support member 18B is fitted in the tip side of the inner wall of the space for filling the writing ink occluding body 12 in the barrel 10. As shown in FIG.

6(a)-(h) are explanatory diagrams of the support member 18B.
The support member 18B is made of a transparent or translucent body. The support member 18B of the present embodiment is made of a material having visibility, such as styrene-isoprene resin, ionomer resin, SBR-PP blend resin, acrylic resin, nylon resin, polymethylpentene, PC (polycarbonate), transparent ABS resin. The visible light transmittance is sufficient so that the writing direction can be visually recognized, and it is preferably composed of a material having a visible light transmittance of 50% or more, as in the first embodiment. .

As shown in FIG. 6(f), grooves 32 are formed on the left and right sides of the rear portion of the support member 18B. By press-fitting the rear half portion of the support member 18B into the front end of the front barrel 20, the groove 32 forms an air replacement hole between the inner wall of the front end of the front barrel 20 (Fig. 7(c)). reference). Therefore, the air replacement holes are opened on the left and right sides of the writing instrument.

In addition, at the front end of the support member 18B, the outer peripheral surface is tapered and uneven in the circumferential direction. It has a star-shaped or flower-shaped shape. Of course, this is an example and can be of various shapes. Since the support member 18B is transparent, the color of the writing part 14B can be easily recognized. The appearance design property is improved by planning.

The writing instrument according to the second embodiment functions as follows.
That is, the fluid immersed in the writing ink occluding body 12 (FIG. 5(c)) is guided toward the tip by the capillary force of the writing portion 14B, reaches the tip of the writing portion 14B, and is immersed therein. It becomes possible to write on the target part. Also, the air that has flowed in from the air replacement hole of the groove 32 reaches the internal space of the barrel 10 where the writing ink occluding body 12 exists. As a result, the air exchange of the fluid can be performed without any trouble.

Here, when a sudden impact is applied to the writing instrument in the tip direction, most of the fluid is blocked by the inner stepped portion of the barrel 10, but part of it passes through the air replacement hole (groove 32). Become. However, since the air replacement hole has a 90° bent portion (32a: see FIG. 6(f)) on the tip side and it is necessary to turn 90° to both the left and right sides, the air does not directly leak out to the outside. Then, the fluid temporarily held on the tip side in the air replacement hole is pushed back toward the writing ink occluding body 12 by the outside air flowing in from the air replacement hole during that time.

[Description of Writing Ink Composition]
Next, the writing ink composition used in the writing instrument will be described in the first embodiment, the second embodiment, and the third and subsequent embodiments described later.
The ink composition for writing instruments that can be used is not particularly limited. From the standpoint of exhibiting excellent stability and a function that does not cause bleeding or strike-through in drawn lines, it is preferable to use a coloring agent, trimethylglycine, pentaerythritol, 10% by mass or less of a water-soluble organic solvent, and water. It is desirable to use an ink composition for writing instruments containing at least

Examples of coloring agents that can be used include dyes that dissolve or disperse in water, conventionally known inorganic and organic pigments such as titanium oxide, pigment-containing resin particle pigments, pseudo pigments obtained by coloring resin emulsions with dyes, and fluorescent pigments. Pigments, white plastic pigments, silica or mica-based pigments coated with multiple layers of iron oxide or titanium oxide on the surface layer, etc. can be used as long as the effects of the present invention are not impaired.
Examples of dyes include acidic dyes such as Eosin, Foxin, 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, Violet B00B; Dyes; basic dyes such as rhodamine and methyl violet, and fluorescent dyes.

Examples of inorganic pigments include azo lakes, insoluble azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, and nitroso pigments. More specifically, carbon black, titanium black, zinc white, red iron oxide, aluminum, chromium oxide, iron black, cobalt blue, iron oxide yellow, viridian, zinc sulfide, lithopone, cadmium yellow, vermillion, cadmium red, yellow lead, Inorganic pigments such as molybdate orange, zinc chromate, strontium chromate, white carbon, clay, talc, ultramarine blue, precipitated barium sulfate, barite powder, calcium carbonate, lead white, dark blue, dark blue, manganese violet, aluminum powder, brass powder, etc. , C.I. I. Pigment Blue 17, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 17, C.I. I. Pigment Blue 27, C.I. I. Pigment Red 5, C.I. I. Pigment Red 22, C.I. I. Pigment Red 38, C.I. I. Pigment Red 48, C.I. I. Pigment Red 49, C.I. I. Pigment Red 53, C.I. I. Pigment Red 57, C.I. I. Pigment Red 81, C.I. I. Pigment Red 104, C.I. I. Pigment Red 146, C.I. I. Pigment Red 245, C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 34, C.I. I. Pigment Yellow 55, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 166, C.I. I. Pigment Yellow 167, C.I. I. Pigment Orange 5, C.I. I. Pigment Orange 13, C.I. I. Pigment Orange 16, C.I. I. Pigment Violet 1, C.I. I. Pigment Violet 3, C.I. I. Pigment Violet 19, C.I. I. Pigment Violet 23, C.I. I. Pigment Violet 50, C.I. I. Pigment Green 7 and the like.
As the fluorescent pigment, conventionally known ones can be appropriately used, and examples thereof include inorganic fluorescent pigments such as zinc sulfide, zinc silicate, cadmium sulfide, strontium sulfide, and calcium tungstate, and organic fluorescent pigments obtained by dyeing polymer compounds. .
Specific examples of organic fluorescent pigments include NKW series (manufactured by Nihon Shokuryo Kagaku Co., Ltd.), Shinroihi Color Base SW series, SF series (manufactured by Shinroihi Co., Ltd.), and Victoria series such as Victoria Yellow G-20 (manufactured by Mikuni Shiso Co., Ltd.). etc.

These colorants can be used singly or in combination of two or more.
The content of these colorants can be appropriately adjusted within the range of 0.1 to 60 mass % (hereinafter, "mass %" is simply referred to as "%") relative to the total amount of the ink composition.

The trimethylglycine used (also known as glycine betaine, (CH ₃ ) ₂ N ⁺ (CH ₃ )CH ₂ COO ⁻ ) is used to act as a moisturizing agent or the like, and is incorporated in the water-based ink composition for writing instruments. Also, the ink performance is not deteriorated, and the drying resistance of the pen tip, the drying property of the drawn line, and the low-temperature stability of the ink can be exhibited.

The trimethylglycine content is desirably 0.5 to 50%, preferably 1 to 15%, more preferably 2 to 10%, relative to the total amount of the ink composition.
If the content is less than 0.5%, the effect of suppressing drying of the nib is not sufficient. result in a decline.

The pentaerythritol [C(CH ₂ OH) ₄ ] used is used to act as a moisturizing agent and the like. While suppressing the drying of the ink, it has unprecedented dryness of drawn lines, excellent low-temperature stability of ink, and excellent performance without bleeding or strike-through in drawn lines.

The pentaerythritol content is desirably 0.5 to 8%, preferably 2 to 5%, relative to the total amount of the ink composition.
If the content is less than 0.5%, the effect of suppressing the dryness of the nib is insufficient, and the synergistic action with trimethylglycine cannot be exhibited. The effect of the synergistic action with trimethylglycine does not change so much, and precipitation at low temperatures and deterioration of storage stability are caused.

Examples of water-soluble organic solvents to be used include alcohols such as ethanol, isopropyl alcohol, n-butyl alcohol, ethylene glycol and diethylene glycol, amides such as formamide and derivatives thereof, sulfoxides such as dimethyl sulfoxide, and ethylene glycol monomethyl ether. , ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene Glycol butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, ethylene glycol monoethyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, propylene Ethers such as glycol ethyl ether and propylene glycol tertiary butyl ether can be mentioned, and these can be used singly or in combination of two or more.
The content of these water-soluble organic solvents is desirably 10% or less, preferably 7% or less, more preferably 5% or less, relative to the total amount of the ink composition.
By setting the content of these water-soluble organic solvents to 10% or less, it is possible to exhibit an excellent function of drawing line drying.

The ink composition for a writing instrument used in the writing instrument of the present invention is prepared with water (purified water, distilled water, ion-exchanged water, pure water, etc.) as the remainder (solvent) in addition to the above components. For example, optional components such as surfactants, antiseptic agents, antibacterial agents, pH adjusters, water-soluble resins, and resin emulsions can be contained as appropriate within a range that does not impair the effects of the present invention.

Surfactants that can be used include, for example, sorbitan fatty acid ester, glycerin fatty acid ester, decaglycerin fatty acid ester, polyglycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbit fatty acid ester, polyoxyethylene glycerin fatty acid ester. , polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene castor oil, polyoxyethylene lanolin, lanolin, alcohol, beeswax derivative, polyoxyethylene alkyl Nonionic surfactants such as amines and fatty acid amides; Anionic surfactants such as sulfonates, alkyl phosphates, polyoxyethylene alkyl ether phosphates; perfluoroalkylethylene oxide adducts, perfluoroalkyltrimethylammonium salts, perfluoroalkylcarboxylates, fluorine perfluoroalkyl ester, perfluoroalkyl sulfonate, perfluoroalkyl hydrophilic group-containing oligomer, perfluoroalkyl hydrophilic group-containing urethane, perfluoroalkyl phosphate, perfluoroalkyl betaine, perfluoroalkylamine oxide, perfluoroalkyl Fluorinated surfactants such as fluoroalkylammonium salts, perfluoroalkylalkoxylates, and perfluoroalkylpolyoxyethylene ethanol can be mentioned. These surfactants can be used singly or in combination of two or more.
Examples of antiseptics or antibacterial agents include phenol, sodium omadine, sodium benzoate, and benzimidazole compounds.
Examples of pH adjusters include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, amine compounds such as triethanolamine, diethanolamine, monoethanolamine, dimethylethanolamine, morpholine and triethylamine, and ammonia. is mentioned.
Examples of water-soluble resins include polyacrylic acid, water-soluble styrene-acrylic resin, water-soluble styrene-maleic acid resin, water-soluble maleic acid resin, water-soluble styrene resin, polyvinylpyrrolidone, polyvinyl alcohol, water-soluble ester- Acrylic resin, ethylene-maleic acid copolymer, polyethylene oxide, water-soluble urethane resin, and the like.
Examples of resin emulsions include acrylic emulsions, vinyl acetate emulsions, urethane emulsions, styrene-butadiene emulsions, and styrene acrylonitrile emulsions.
These water-soluble resins and resin emulsions can be used singly or in combination of two or more.

A conventionally known method can be used to produce this writing instrument ink composition. It contains at least water and can be obtained by blending predetermined amounts of each component in the aqueous solution and stirring and mixing with a stirrer such as a homomixer or a disper. Further, if necessary, coarse particles in the ink composition may be removed by filtration or centrifugation, or the ink composition may be produced while defoaming, heating, or cooling.

Why is the ink composition for writing instruments used in the writing instrument of the present invention configured as described above excellent in the drying property of drawn lines and in the low-temperature stability of the ink while suppressing the drying of the pen tip and preventing bleeding and strike-through in the drawn lines? It can be guessed as follows whether it expresses a function that does not exist.
That is, the ink composition for a writing instrument used in the writing instrument of the present invention contains at least a colorant, trimethylglycine, pentaerythritol, 10% by mass or less of a water-soluble organic solvent, and water. Glycine and pentaerythritol are components that suppress the drying resistance of the nib, and they work synergistically by using them together in a water-based ink composition for writing instruments rather than using each of them alone. is clear. The reason for this is not entirely clear, but it is believed that the synergistic effect prevents the nib from drying out, while also providing excellent line drying and low-temperature stability of the ink, as well as excellent performance without bleeding or show-through in drawn lines. guessed.
The ink composition for writing utensils used in the present invention has an extremely excellent sustained effect that exerts the above effect, and the period and duration of the effect are long, and trimethylglycine and pentaerythritol are water-soluble. It also has excellent stability over time.
Therefore, by using the writing ink composition having the composition described above in the writing instrument of the present invention, when writing with the writing instrument while holding the writing instrument from the visibility of the holder, the writing part can be made clearer while looking at the writing target part. In addition to the excellent effect of being able to achieve a smooth finish, it is a writing instrument that has excellent drying properties of drawn lines and low-temperature stability of ink while suppressing drying of the writing part (pen tip), and can express functions without bleeding or strike-through in drawn lines. is obtained.

[Writing implement of the third embodiment]
Next, it is explanatory drawing of the writing instrument which concerns on 3rd Embodiment of this invention.
7(a)-(d) show the writing instrument according to the third embodiment of the present invention, (a) is a view from the front, (b) is a perspective view, (c) is a front view, and (d) shows a longitudinal sectional view. 8(a)-(h) are parts diagrams showing a support member (corresponding to a "holder") 18C of this writing instrument. In addition, the barrel 10, the writing ink occluding body 12, and the front barrel 20 are given the same reference numerals as in the second embodiment.

In this writing instrument, as shown in FIGS. 7(a)-(d), a brush-like writing portion 14C protrudes from the tip of a holding member 18C within the tip of the front barrel 20. As shown in FIG. The rear end of the writing portion 14C is inserted into and connected to the writing ink occluding body 12, and the writing portion 14C passes through the axial center of the support member 18C.

As the writing part 14C, as in the second embodiment, in the case of a writing brush, a bundle of polybutylene terephthalate fibers can be used as the material so as to sharpen the tip. Nylon, polyester, and acrylic can be used as the material.

As shown in FIGS. 8(a) to 8(h), the holding member 18C is made of transparent resin and has an outer surface shape in which a large number of triangular surfaces are combined. As shown in FIG. 8(a), it has a symmetrical elliptical shape when viewed from the front. Further, grooves 32 are formed on the left and right sides of the rear portion of the holding member 18C. By press-fitting the rear half portion of the support member 18C into the front end of the front barrel 20, the groove 32 forms an air replacement hole between the inner wall of the front end of the front barrel 20 (Fig. 7(d)). reference)

The resin of the holding member 18C may be the same material as in the first embodiment, such as styrene-isoprene resin, ionomer resin, SBR-PP blend resin, acrylic resin, nylon resin, polymethylpentene. , PC (polycarbonate), or transparent ABS resin, and is preferably made of a material having a visible light transmittance of 50% or more.
In addition, in order to enhance the impression of surface reflection in the support member 18C, it is preferable that the surface that shines intermittently switches when the angle changes.

The support member 18C can effectively give the impression of shining when many faces successively shine with a small angle change, such as a diamond cut with many triangular faces.
Further, in order to enhance the impression of the surface reflection of the support member 18C, it is preferable that the edge (ridge line) is well projected. For example, it is preferable that the radius of the edge is 0.5 mm or less.

In addition, the support member 18C can emphasize both surface reflection and total internal reflection by increasing the thickness of the transparent component (transparent resin component) and thinning the pen core.
In addition, the support member 18C is made of a material with a high Abbe number (small dispersion), and the light becomes colder and has a diamond-like brilliance. In this case, a material with a high refractive index is more likely to cause both surface reflection and total internal reflection.

[Writing implement of the fourth embodiment]
Next, it is explanatory drawing of the writing instrument which concerns on 4th Embodiment of this invention.
9(a)-(d) show the writing instrument according to the fourth embodiment of the present invention, (a) is a view from the front, (b) is a perspective view, (c) is a front view, and (d) is shown in longitudinal section. FIGS. 10(a) to 10(g) are parts diagrams showing a support member (corresponding to a "holder") 18D of this writing instrument. FIGS. 11(a) to 11(e) are explanatory diagrams of the refracted state of light rays of the support member 18D.
9 and 10, the barrel 10, the writing ink occluding body 12, and the front barrel 20 are assigned the same reference numerals as in the third embodiment.

As shown in FIG. 10(b), the support member 18D according to the fourth embodiment has a substantially pentagonal shape when viewed from the front, and is vertically asymmetrical.
Referring to FIG. 11, the fact that the support member 18D can contribute to light refraction when the support member 18D has a substantially pentagonal cross-sectional shape will be described.

FIGS. 11(a) to 11(e) show a support member 18C according to the third embodiment, the cross section of which is vertically and horizontally symmetrical. The support member 18C has a substantially oval shape with an outer edge formed by combining straight lines when viewed in cross section, and forms parallel surfaces such as an upper surface and a lower surface. As shown in FIG. 11A, parallel light L1 incident from one upper surface is refracted from the surface and enters the interior, reaches the other lower surface in parallel inside, and is refracted from the other surface and emitted ( The traveling path of the light L1 is indicated by a dashed line). Even if the light L1 is incident, it passes through the supporting member 18C, so that it is difficult to produce a brilliant brilliance.

On the other hand, in the support member 18D according to the fourth embodiment, as shown in FIGS. is lost. As shown in FIG. 11(c), a support member 18D having a pentagonal cross section has surfaces 18D1 to 18D5. Parallel light L2 incident from one upper surface 18D1 is refracted from the surface 18D1 and enters the interior, is further reflected and refracted by the lower surfaces 18D3 and 18D4, is scattered upward, and is emitted after being reflected and refracted by various other surfaces 18D1 to 18D5. (the traveling path of the light L2 is indicated by a dashed line).

Therefore, the frequency of total internal reflection can be increased by making the outer shape of the support member 18D into a pentagonal shape or the like to eliminate parallel surfaces (parallel surfaces). Therefore, the light L2 incident on the support member 18D is reflected by each surface and emitted, so that the light shines brightly. When the writing instrument is used, the reflected light changes and shines as the incident angle of the light from the light source changes.

As shown in FIG. 11(b), the support member 18D is a cylindrical passage through which the writing part 14D passes, but the outer shape can be made pentagon or the like to eliminate parallel surfaces. In addition to eliminating the parallel surfaces, the path 18Db through which the writing section 14D is inserted in the support member 18D is provided with concave lines (such as cross cores) as shown in FIGS. By forming the recesses 18Da, the frequency of total internal reflection can be further increased by the recessed streaks 18Da to further increase the brilliance.

Further, as shown in FIGS. 9 to 11, the support member 18D can emphasize both surface reflection and internal total reflection by increasing the thickness of the transparent part and thinning the pen core.
In addition, the support member 18D is made of a material with a high Abbe number (small dispersion), and the light becomes colder and has a diamond-like brilliance. In this case, a material with a high refractive index is more likely to cause both surface reflection and total internal reflection.

[Writing instrument of the fifth embodiment]
Next, it is explanatory drawing of the writing instrument which concerns on 5th Embodiment of this invention.
12 (a) to (d) show a writing instrument according to a fifth embodiment of the present invention, (a) is a view from the front, (b) is a perspective view, (c) is a front view, (d ) is shown in longitudinal section. FIGS. 13(a) to 13(j) are component diagrams showing a support member (corresponding to a "holder") 18E of this writing instrument. FIG. 14 is an explanatory diagram of the refracted state of light rays of the support member 18D.
12 to 14, the barrel 10, the writing ink occluding body 12, and the front barrel 20 are assigned the same reference numerals as in the third and fourth embodiments.

As shown in FIGS. 12 and 13, the support member 18E according to the fifth embodiment has an hourglass shape with recesses formed on both side surfaces when viewed from the front. It makes the pen core invisible from a certain angle (stealth tipper).

As shown in FIG. 13, the support member 18E has a square cross-sectional core shape (that is, internal passage shape) of an internal passage 18Ea through which the writing part 14E passes, so that light is totally internally reflected within the support member 18E. The pen core of the writing part 14E is made invisible by .

Further, the support member 18E has a concave side surface 18Eb that is recessed in an arc shape on the outside, so that the light entering the support member 18E is refracted and the light is easily totally internally reflected on the side of the internal passage 18Ea.

In addition, as shown in FIG. 14, by passing the metal pipe 34 between the support member 18E and the writing part 14E, even at an angle where the pen core of the writing part 14E is originally visible, the outer surface of the metal pipe 34 has a reflecting function. (Reflective function due to surface properties such as total reflection and specular reflection) provides brightness like total internal reflection, making it possible to make the writing part 14E (pen core) in the support member 18E invisible from 360-degree directions. .

In addition, when the support member 18E is made of a material with a high refractive index, total internal reflection is more likely to occur, and the range in which the pen core of the writing section 14E is not visible is widened.
As shown in FIG. 14, in a specific implementation product of the support member 18E, the concave side surface 18Eb has the effect of a concave lens, and as shown in the cross section, the incident light L3 (indicated by the two-dot chain line L3) The incident light L3 (reflected at the point P) is internally totally reflected within ±12 degrees with respect to the pen tip, thereby exhibiting a stealth property in which the writing portion 14E pen core cannot be seen. In other words, the angle of incidence increases at point P, and total reflection tends to occur.

In this case, a structure can be provided in which a reflective pipe 34 is passed through the internal passage 18Ea, the writing part 14E is passed through the pipe 34, and the pen core of the writing part 14E is covered with the pipe 34.

As a result, the incident light L3 is reflected by the wall surface of the internal passage 18Ea (internally reflected by the support member 18E) and irregularly reflected by the pipe 34, making it difficult or impossible to see the entire circumference of the writing section 14E. The material of the pipe 34 is preferably a reflective material such as metal, and stainless steel, aluminum, or a nickel-chromium plated product is preferable.

As described above, in the writing instrument of the fifth embodiment, the incident light is totally internally reflected inside the support member 18E, so that the internal writing section 14E cannot be seen and the stealth property can be improved.
Therefore, the writing part 14E inside is invisible to the user and only the reflected light appears to shine, so that a brilliant impression can be given. Also, the pipe 34 can be provided to further enhance stealth.

[Writing instrument of the sixth embodiment]
Next, a writing instrument according to a sixth embodiment of the invention will be described.
The writing instrument according to the sixth embodiment of the present invention has the same shape and appearance structure as the writing instrument of the fifth embodiment shown in FIGS. The texture is improved by using more light scattering.

The material of the supporting member is a transparent resin to which fine particles (of the order of several tens of nanometers) are added, so that it can be colored blue by Rayleigh scattering.
When viewed at a specific angle, the part where the content liquid guide part (writing material such as the pen core of the writing part) is visible in the surface area of the support member, which is a transparent member of the hard pen tip, is 50% or less. Appropriate.
In addition, the hard pen tip, that is, the support member, which is a transparent member, has a maximum thickness of 1 mm or more in a cross section perpendicular to the axial direction LD, or the diameter of the guide portion (writing portion pen core) 14E and the support member. It is preferable that the outer diameter ratio of the transparent member is 1:3 or more. That is, the outer diameter of the transparent member is preferably three times or more the diameter of the guide portion 14E.

[Writing instrument of the seventh embodiment]
Next, a writing instrument according to a seventh embodiment of the invention will be described.
15(a)-(c) show a writing instrument according to the seventh embodiment of the present invention, (a) is a perspective view from the front, (b) is a side view, (c) is C- of (b) It is a longitudinal cross-sectional view along line C. FIG. 16(a)-(d) are parts diagrams of the barrel of this writing instrument. 17(a)-(f) are parts diagrams of a support member (corresponding to a "holding body") 18F of this writing instrument. Also, FIG. 18 is an explanatory diagram of the transparency of the support member 18F. 15 to 18, the barrel 10, the writing ink occluding body 12, and the front barrel 20 are denoted by the same reference numerals as in the fifth embodiment shown in FIGS.

In the writing instrument according to the seventh embodiment, a support member 18F for inserting and supporting the writing portion (pen core) 14F is formed of a transparent member. As shown in FIGS. 15 and 17, the support member 18F has both side surfaces (the front surface as viewed from the user) cut into flat surfaces as viewed from the front, and the overall axial cross section is an approximately ellipse. is formed into an almost emerald-cut shape. An internal passage 18Fa having a hexagonal or diamond-shaped cross section is formed through the support member 18F in the axial direction, and the writing section 14F is inserted through the internal passage 18Fa. The tip of the internal passage 18Fa has a circular cross section, and the cross section of the writing section 14F is circular.

In this case, the support member 18F is made of the same material as in the first embodiment, and has a flat outer surface 18Fb and a substantially elliptical cross section. It is made difficult or invisible from the direction of the substantially flat outer surface 18Fb in a state where the portion 14F is passed through (stealth chipler).
Since the support member 18F has a shape in which a large flat surface is arranged on the front side, it can be made into a shape that can appeal and emphasize the transparency and bulkiness.

The structure of the support member 18F refracts the light entering the support member 18F, and the shape of the support member 18F facilitates internal total reflection on the side of the internal passage 18Fa. It has a substantially hexagonal shape in cross section.

In this case, making the writing section 14F less visible or invisible will be described. As shown in FIG. 18, in the core shape (shape of the internal passage 18Fa) of the internal passage 18Fa through which the writing section 14F passes, the width W1 in the direction along the visible outer surface 18Fb is narrowed and the angle θ is sharpened (acute angle: angle .theta.<90.degree.) to facilitate total internal reflection. The length W2 is longer than the width W1 (W2>W1), where W2 is the length in the direction perpendicular to the outer surface 18Fb. Preferably, half the length is longer than the width W1 ((1/2)W2>W1).

By making the angle θ sandwiched by two sides of the outer side surface 18Fb of the specific cross-sectional hexagonal shape (or gentle rhombic shape) an acute angle in this way, light can be totally internally reflected within the supporting member 18F. . As a result, the pen core of the writing section 14F can be made invisible. Specifically, as shown in FIG. 18, the reflected light L2 from the internal passage 18Fa can be deflected laterally without going to the other outer side surface 18Fb with respect to the incident light L1 to the one outer side surface 18Fb. As a result, the back side of the writing section 14F can be seen, and conversely, the writing section 14F is difficult to see or cannot be seen.

As shown in FIG. 18, by sharpening the core shape of the internal passage 18Fa (the angle θ is an acute angle), the support member 18F easily undergoes total internal reflection on the side surface of the internal passage 18Fa. , the writing part 14F in the internal passage 18Fa becomes difficult to see, and there is also a secondary effect that the sense of transparency increases and the design is improved.

In addition, in the writing instrument of the seventh embodiment, the writing ink absorbing body 12 is supported by the ribs 10a inside the barrel 10. As shown in FIG. By forming the ribs 10a, the thin portion and the surface area thereof are reduced compared to the case where the inside of the barrel 10 is merely a smooth surface.

As a modification of the seventh embodiment, interference fringes can be formed on the peripheral surface of the support member 18F. In particular, the outer surface 18Fb is flat, and an interference fringe pattern can be formed on the outer surface 18Fb to improve the appearance design.
This pattern is expensive to apply fringe patterns to mold parts. Therefore, we succeeded in producing an interference fringe pattern at a low cost with a simple processing that only controls the feed of an NC processing machine. In the mold, it was mounted as a nest for the flat part (outer surface). Also, in order to improve the transferability of the interference fringe pattern, a mold structure that is easy to apply a filling pressure is required.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[Example 1]
Writing implements and inks conforming to the following composition and FIGS. 1 to 4 were used. As for the dimensions of the writing lead, holder, etc., the sizes shown below were used.

(Structure of ink supplier 15)
PET fiber core, porosity 65%, small diameter part: φ2 × 7 mm + large diameter part: φ4 × 15 mm
(Structure of writing lead 16)
PE sintered core, porosity 60%, drawing line width of writing part 16c: 4 mm, ink guiding part: diameter φ
2mm
(Configuration of holder 18)
Hard material: made of acrylic resin, visible light transmittance 80% [Reflectance was measured with a multi-light source spectrophotometer (MSC-5N, manufactured by Suga Test Instruments Co., Ltd.) and taken as visible light transmittance. ]
When viewed from the side of the holding member 18C at a specific angle, 48% of the surface area of the holding body showed the writing.

(Structure of writing instrument members other than writing core 16 and holder 18)
Ink absorbing material: PET fiber core, porosity 85%, φ10×85 mm
Writing instrument body, cap: made of polypropylene (PP)

(Ink composition)
As the ink, an ink having the following composition (100% by mass in total) was used.
Humectant: trimethylglycine (glycine betaine) 7.5% by mass
Pentaerythritol 4.5% by mass
Coloring agent: NKW-4805 yellow (manufactured by Nippon Fluorescent Co., Ltd.) 40.0% by mass
Antiseptic: 0.3% by mass of Bioace (manufactured by Kei Kasei Co., Ltd.)
pH adjuster: triethanolamine 1.0% by mass
Fluorinated surfactant: Surflon 8111N (manufactured by AGC Seimi Chemical Co., Ltd.) 0.2% by mass
Water-soluble organic solvent: Ethylene glycol 3.0% by mass
Water (solvent): ion-exchanged water 43.5% by mass

In the writing instrument of Example 1, the writing part guides the writing ink from the barrel and consists of a writing body that can be written and a holding body that holds the writing body, and the holding body is made of a hard material having visibility. In addition, since the visible part of the cursive body can be visually recognized thinly, it is possible to make the written part clearer while looking at the part to be written when writing with the writing instrument by holding the writing instrument from the visibility of the holding body. confirmed.
Further, in the holding body, the thickness of the section perpendicular to the axial direction and the thickest part are set to 1 mm or more, or the ratio of the outer diameter of the writing body to the outer diameter of the holding body is set to 1:3. By doing so, it was found that the writing part can be made clearer while looking at the part to be written.
Furthermore, in the first embodiment, since the holding body has the writing part and the ink supply part at the center and the outer peripheral part in the radial direction, the ink supply from the ink absorbing body to the writing surface of the writing body is a mechanism in which ink is supplied from two directions, so that the amount of ink supplied is suitable without causing an ink supply shortage.
Furthermore, this writing instrument was set in an automatic writing device, and in accordance with JIS S6037, linear writing was performed on high-quality paper at a writing angle of 65°, a writing load of 1 N, a speed of 7 cm/s, and a distance of 100 m. As a result of using the above preferable ink composition, the ink flow rate is good, and while the drying of the pen tip is suppressed, the dryness of the drawn line and the low temperature stability of the ink are excellent, and the drawn line does not bleed. It turned out that the function without penetration was expressed.

The writing instrument of the present invention can be used for writing with writing ink in the writing section.

10 Axle cylinder 10a Rib 12 Writing ink occluding body 14 Writing part (first embodiment)
14B writing unit (second embodiment)
14E writing unit (fifth embodiment)
14F writing unit (seventh embodiment)
16 Ink guide for writing (Cursive)
16A Writing ink guide (cursive)
18 support member (holding body according to the first embodiment)
18B support member (holding body according to the second embodiment)
18C support member (holding body according to the third embodiment)
18D support member (holding body according to the fourth embodiment)
18E support member (holding body according to the fifth embodiment)
18F support member (holding body according to the seventh embodiment)
20 front barrel 22 writing porous body 36 inner plug 36A inner plug

Claims (2)

A writing instrument having a barrel containing writing ink and a writing part attached to one end of the barrel, wherein the writing part guides the writing ink from the barrel and draws the writing ink. and a holding body for holding the writing body, the holding body is formed of a hard material having visibility, the holding body is provided with the writing body, and a specific In the surface area of the holding body when viewed from an angle, the part where the writing is visible is 50% or less, and the holding body has a substantially elliptical cross section and a flat surface on the peripheral surface. 1. A writing utensil characterized in that interference fringes are formed , the flat surface being formed on the opposite surface in the major axis direction, and the interference fringes being formed on the opposite surface in the minor axis direction . 2. The writing instrument according to claim 1 , wherein the writing ink contains at least trimethylglycine, pentaerythritol, 10% by mass or less of a water-soluble organic solvent, and water.

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