JP2023120452A - writing instrument - Google Patents

Abstract

To provide a writing instrument that allows visual recognition of the shape of a pen tip, the color tone, and the remaining amount of ink in the writing instrument, without impairing the appearance due to discoloration or browning of the handwriting formed by the writing instrument from the beginning, while the writing instrument uses a member formed of a transparent material.SOLUTION: The writing instrument comprises an ink, an ink occlusion body 7 containing the ink, a barrel 8 containing the ink occlusion body 7, a pen tip 3 capable of discharging ink, a holder 4 holding the pen tip 3, and a cap 2 detachably attached to the pen tip side of barrel 8 and formed of a transparent material. The cap 2 contains an ultraviolet absorber or a transparent ultraviolet shielding agent, or a light stabilizing layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent is provided on the surface of the cap 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to writing instruments. More specifically, the present invention relates to a writing utensil in which the lightfastness of ink contained therein is improved.

2. Description of the Related Art Conventionally, there are many colorants contained in ink contained in writing instruments whose color tone is faded or discolored by light. Therefore, it has been disclosed to add UV absorbers such as benzophenone-based, salicylic acid-based, benzotriazole-based, and cyanoacrylate-based UV absorbers to the ink (see, for example, Patent Documents 1 and 2).

JP-A-62-106971 JP-A-9-279080

In the techniques disclosed in Patent Documents 1 and 2, the UV absorber has very poor solubility in the medium, and can be added only in a small amount, especially when used in water-based ink. was difficult to obtain.

In recent years, writing instruments have been widely used in which the shape of the nib, the color tone of the ink, and the remaining amount of ink can be visually recognized, and the cap, barrel, and ink storage tube are made of a transparent material and housed inside. The contained ink itself tends to be exposed to light, and in systems using colorants such as dyes, fluorescent pigments, reversible thermochromic materials, and photochromic materials that have relatively poor lightfastness, the colorant fades in the ink. As a result, handwriting obtained by writing also shows discoloration and browning, which tends to impair the commercial value. In addition, in order to prevent the colorant from fading or browning in the ink, the cap, barrel, and ink storage tube cannot be made of transparent materials. The color tone and remaining amount of ink cannot be visually recognized.

The present invention has been made in view of the above findings, and an object of the present invention is to provide a writing instrument using a member formed of a material having transparency, while the handwriting formed by the writing instrument is To provide a writing utensil capable of visually recognizing the shape of the nib and the color tone and remaining amount of ink in the writing utensil without causing fading or browning from the initial stage to impair the appearance. In the present invention, "front" refers to the pen tip side, and "rear" refers to the opposite side.

The present invention provides a reversible thermochromic material comprising (a) an electron-donating organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction of the components (a) and (b) occurs. an ink containing a colorant selected from materials, photochromic organic materials, dyes, and fluorescent pigments; an ink occlusion body containing the ink; a barrel containing the ink occlusion body; and a pen capable of ejecting the ink. A writing instrument comprising a tip, a holder for holding the pen tip, and a cap detachably attached to the pen tip side of the barrel and formed of a material having transparency, wherein the cap is attached to the cap. A writing instrument containing an ultraviolet absorber or a transparent ultraviolet shielding agent, or provided with a light stable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent on the surface of the cap.

According to the present invention, a transparent material is obtained by containing an ultraviolet absorber or a transparent ultraviolet shielding agent in the cap, or by providing a photostable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent on the surface of the cap. Although it is a writing instrument using a member formed by can.

The present invention is a writing instrument that uses a member formed of a material having transparency, yet is an excellent writing instrument that does not cause discoloration or browning of handwriting formed by the writing instrument from the initial stage and impairs the appearance. Since the shape of the pen tip and the color tone and remaining amount of ink in the writing instrument can be visually recognized, a writing instrument with high commercial value can be provided.

It is a longitudinal section showing an embodiment of the present invention. FIG. 2 is an enlarged view of a main portion of FIG. 1; FIG. 3(a) is a vertical cross-sectional view of a holder according to an embodiment of the present invention. FIG. 3(b) is a cross-sectional view taken along line AA of FIG. 3(a). FIG. 3(c) is a cross-sectional view taken along line BB of FIG. 3(a). FIG. 4(a) is a front view of the nib of the embodiment of the present invention. FIG. 4(b) is a perspective view of the pen tip. FIG. 3 is an enlarged vertical cross-sectional view of a main part of FIG. 2; FIG. 6 is an exploded view of the front and rear axles of FIG. 5; (Other parts omitted) FIG. 4 is an explanatory diagram showing discoloration behavior of a heat-erasable microcapsule pigment. FIG. 3 is an explanatory diagram showing discoloration behavior of color memory-retaining microcapsule pigments. FIG. 3 is an explanatory diagram showing discoloration behavior of a heat-color-developing microcapsule pigment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The writing instrument 1 mainly comprises a cap 2, a pen tip 3, a holder 4 holding the pen tip 3, an ink occluding body 7, and a front barrel 5 and a rear barrel 6 accommodating the ink occluding body 7 inside. Become. Then, the holder 4 is press-fitted into the holder fitting portion 58 of the front shaft 5 . Also, the writing instrument 1 has the front barrel 5 detachably provided in the opening of the rear barrel 6 which accommodates the ink occluding body 7 therein, and removes the front barrel 5 from the opening of the rear barrel 6 to remove the ink occluding body 7. It is a writing utensil for replacing or replenishing the ink occluding body 7 with ink.
The structure of the writing instrument 1 is not particularly limited. A structure that supplies ink to the tip, a structure in which ink is stored directly inside the barrel, and a structure in which a comb groove-shaped ink flow rate adjusting member or an ink flow rate adjusting member consisting of a fiber bundle is interposed, and ink is stored directly inside the barrel. Another example is a marking pen having a structure in which a predetermined amount of ink is supplied to the writing tip by a valve mechanism.

Pen tip One end of the pen tip 3 protrudes forward from the front edge 44 of the front opening of the holding body 4 as the writing part 31 , and the other end (rear part 35 ) is the ink occluding body 7 . is connected in a stabbing manner to one end of the Note that the writing portion 31 is processed into a chisel shape. Moreover, the writing part 31 is not limited to a chisel shape, and may be processed into a shell shape, a quadrangular prism shape, a plate shape, or other shape according to the purpose. The form of the writing instrument 1 of the present invention is not limited to the illustrated example, and may be a double-headed writing instrument in which pen tips of different forms are attached to both ends of the ink occluding body 7 .

As shown in FIGS. 2 and 4, the pen tip 3 has a front portion 33 having a writing portion 31 at its tip, and a cylindrical central portion 34 whose outer surface is sandwiched between the holder 4 and the front shaft 5 in the front-rear direction. , and a cylindrical rear portion 35 connected to one end of the ink occluding body 7 in a piercing manner. The front portion 33 of the pen tip 3 has a substantially rectangular cross section, and has flexibility to bend and deform toward the long sides of the substantially rectangular cross section during writing. The pen tip 3 has a flat portion on the long side of its rectangular cross section. As a result, the colorant tends to fade or brown in the conventional ink, and thus the handwriting obtained by writing also tends to fade or brown, which tends to impair the commercial value. However, according to the present invention, the holder or cap contains an ultraviolet absorber or a transparent ultraviolet shielding agent, or a light stable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent is provided on the surface of the holder, as will be described later. Thus, even though the writing instrument 1 uses a member formed of a transparent material, the handwriting formed by the writing instrument 1 does not deteriorate in appearance due to fading or browning from the beginning, and the shape of the nib and the writing instrument can be improved. The color tone and remaining amount of ink in 1 can be visually recognized.

The pen tip 3 is preferably made of a synthetic resin porous body having open cells. As a result, the degree of freedom in the shape of the pen tip is increased, and a sharp design that appeals to the user's vision can be provided. By using a member (cap) made of a transparent material, the shape of the nib inside the cap can be seen from the outside of the cap, making it possible to emphasize a visual feature (sharp design) to the user. In addition, the handwriting formed by the writing instrument does not lose its appearance due to fading or browning from the beginning, and the shape of the pen tip and the color tone and remaining amount of ink in the writing instrument can be visually recognized. In addition, the pen tip 3 may be of any other type as long as the ink can flow. Specifically, the pen tip 3 includes a fiber pen tip, a felt pen tip, a brush pen tip, a plastic pen tip having an axial capillary passage, and the like. is mentioned.

Also, the pen tip is not particularly limited to the illustrated structure and shape. For example, the pen tip may include an ink guiding portion, a writing portion for drawing out ink from the ink guiding portion, and a visible portion that allows visual recognition of the writing direction directly above the writing portion in the axial direction.

In addition, a pen tip that serves as a writing part and a holder that holds the pen tip and has at least one ink guide part for supplying ink to the writing part are provided. It may be configured such that it has a relay core for supplying ink to an ink guiding portion provided on the body, and the holding body serves as a visual recognition portion for visually recognizing the writing direction.

Ink occluding body The ink occluding body 7 may be made of a member having continuous pores that can be impregnated with ink. body, needle-punched felt body, porous body (for example, open-cell body of synthetic resin such as sponge), and the like. Further, the ink occluding body 7 may be configured to have an outer skin made of a synthetic resin film or the like on its outer peripheral surface.

The ink occluding body has an outer skin formed of a material having transparency on the outer peripheral surface, and the outer skin contains an ultraviolet absorber or a transparent ultraviolet shielding agent, which will be described later, or an ultraviolet absorber is provided on the surface of the outer skin. Alternatively, it is preferable to provide a photostable layer containing a transparent ultraviolet shielding agent. As a result, even though the writing instrument 1 uses a member (ink occluding body) formed of a transparent material, the handwriting formed by the writing instrument 1 does not deteriorate in appearance due to fading or browning from the initial stage. The color tone and remaining amount of ink in the writing instrument 1 can be visually recognized.

When the front shaft 5 is removed from the opening of the rear shaft 6, the ink occluding member 7 is removed from the rear shaft 6 and is held by a holding rib 59 extending axially rearward from the rear end of the longitudinal rib 57. 5 is accommodated and held. As a result, workability is improved when replacing the ink occluding member 7 or replenishing the ink occluding member 7 with ink. Note that the holding rib 59 may extend to the inner surface of the fitting portion 51 .

・Cap The cap 2 that covers the front barrel 5 when not writing is a cylindrical body with a bottom and a peripheral wall that is open at the rear end and closed at the front end, and is made of a transparent synthetic resin ( For example, polypropylene, etc.) can be obtained by injection molding. The cap 2 contains an ultraviolet absorber or a transparent ultraviolet shielding agent, which will be described later, or is provided with a photostable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent on the surface of the cap 2 . As a result, even though the writing instrument 1 uses a member (cap 2) formed of a transparent material, the handwriting formed by the writing instrument 1 does not deteriorate in appearance due to fading or browning from the initial stage. The shape of the nib and the color tone and remaining amount of ink in the writing instrument 1 can be visually recognized.

In particular, the pen tip in which the holding body serves as a visual recognition portion for visually recognizing the writing direction has a sharp design that appeals to the user's visual perception. By using a member (cap) made of a transparent material, the pen tip inside the cap can be seen from the outside of the cap, making it possible to emphasize the visual characteristics (sharp design) to the user. , the handwriting formed by the writing instrument does not lose its appearance due to fading or browning from the beginning, and the shape of the pen tip and the color tone and remaining amount of ink in the writing instrument can be visually recognized.

The cap 2 is detachably connected to the rear axle 6 . Specifically, the rear barrel fitting portion 22 provided on the inner surface of the opening of the cap 2 is fitted to the cap fitting portion 65 provided on the outer surface of the opening of the rear barrel 6 . At the same time, the annular seal portion 21 provided in front of the rear shaft fitting portion 22 is airtightly fitted to the airtight portion 64 provided in front of the cap fitting portion 65 . That is, when not writing, the cap 2 covers the front barrel 5, the inner surface of the cap 2 is fitted to the outer surface of the rear barrel 6, and the inner surface of the cap 2 (the annular seal portion 21) is the outer surface of the rear barrel 6 (the airtight portion 64). is closely attached to the entire circumference.

Moreover, the cap 2 is not particularly limited to the illustrated structure and shape. For example, an inner cap that seals the pen tip may be fitted and fixed to the inner surface of the main body of the cap 2 . In this case, the front and rear barrels made of polypropylene resin and hermetically fitted together, the inner cap made of transparent polypropylene resin, and the cap 2 made of transparent polycarbonate resin are assembled. The inner cap contains an ultraviolet absorber or a transparent ultraviolet shielding agent, which will be described later, or is provided with a light stable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent on the surface of the inner cap. As a result, even though the writing instrument 1 uses the members (the cap 2 and the inner cap) formed of a material having transparency, the handwriting formed by the writing instrument 1 does not lose its appearance due to fading or browning from the beginning. The shape of the pen tip and the color tone and remaining amount of ink in the writing instrument 1 can be visually recognized.

- Barrel The barrel 8 consists of at least one of the front shaft 5 and the rear shaft 6 . The front shaft 5 is a tubular body obtained by injection molding of a synthetic resin with both ends opened. As shown in FIG. 2, the inner surface of the front end portion of the front shaft 5 is formed with a retainer fitting portion 58 into which the outer surface of the rear end portion (second rib 43b) of the retainer 4 is press-fitted. A plurality of (eight here) vertical ribs 57 extending in the axial direction are integrally formed on the rear inner peripheral surface of the retainer fitting portion 58 of the front shaft 5 at equal intervals in the circumferential direction. The center portion 34 of the pen tip 3 is sandwiched between the first contact wall portion 42 of the holder 4 and the second contact wall portion 56a at the front end of the vertical rib 57 in the front-rear direction. As a result, it is possible to prevent the pen tip 3 from falling off from the holder 4 or being buried in the holder 4 (front barrel 5), and to accurately regulate the amount of protrusion of the pen tip 3 from the holder 4. Further, the third contact wall portion 56b at the rear end of the vertical rib 57 sandwiches the front end portion of the ink occluding body 7 in the front-rear direction.

The front shaft 5 is provided with a fitting portion 51 on the rear outer surface thereof, and the fitting portion 51 is detachably engaged with a fitted portion 61 formed on the inner surface of the opening of the rear shaft 6 . The fitting portion 51 includes a cylindrical small-diameter base portion 52 , an outward locking portion 53 provided on the outer surface of the small-diameter base portion 52 , and at least an axially extending portion extending radially across at least the outward locking portion 53 . and one slit 54 . As a result, it is possible to easily set and maintain an appropriate fitting force for detachably connecting the front shaft 5 and the rear shaft 6 .

The fitting portion 51 preferably includes a first outward locking portion 53a, which is the outward locking portion 53, and a second outward locking portion 53b provided behind the first outward locking portion 53a. Prepare. More preferably, the front shaft 5 has a stepped portion 55 with which the opening of the rear shaft 6 abuts, and the first outward locking portion 53a and the second outward locking portion 53b are annular projections 531. As shown in FIG.

Further, the front barrel 5 may be provided with a direction identifying portion formed of a projection extending in the axial direction for identifying the direction of the pen tip 3 on its outer surface. This eliminates the need to visually confirm the direction of the pen tip 3 just before writing, and the pen tip 3 can be used for writing immediately after being exposed.

The rear shaft 6 connected to the rear end of the front shaft 5 is a cylindrical body with an open front end and a closed rear end. polypropylene, etc.) by injection molding. The front shaft 5 is detachably connected to the rear shaft 6 .

The fitted portion 61 includes a cylindrical large-diameter base portion 62 into which the small-diameter base portion 52 is inserted, and an inward locking portion 63 provided on the inner surface of the large-diameter base portion 62 . When the front shaft 5 and the rear shaft 6 are connected, the front shaft and the rear shaft are radially pressed against each other.

The fitted portion 61 is preferably a first inwardly engaging portion 63a which is an inwardly engaging portion 63 and is engaged with the first outwardly engaging portion 53a, and a rear portion of the first inwardly engaging portion 63a. and a second inward engaging portion 63b which is provided in the second outward engaging portion 53b and is engaged with the second outward engaging portion 53b. As a result, the connection between the front barrel 5 and the rear barrel 6 is stabilized, so that the barrel and the stopper are connected without looseness in the axial and radial directions during writing, which improves the writing feel and provides stable writing. It becomes possible.

Also, preferably, when the front shaft 5 and the rear shaft 6 are connected, the outer surface of the fitting portion 51 and the inner surface of the tip end of the rear shaft 6 are not in contact with each other in the radial direction. For example, when the front shaft 5 and the rear shaft 6 are connected, if the outer surface of the fitting portion 51 and the inner surface of the tip of the rear shaft 6 come into contact with each other in the radial direction, the outer diameter of the rear shaft 6 after connection (that is, the airtight portion 64) may become too large. As a result, when the cap 2 is fitted to the outer surface of the rear barrel 6, the fitting force between the cap 2 and the rear barrel 6 may become too high.

On the other hand, when the front shaft 5 and the rear shaft 6 are connected, if the outer surface of the fitting portion 51 and the inner surface of the tip end of the rear shaft 6 are not in contact with each other in the radial direction, the fitting portion 51 is not in contact with the airtight portion 64 . does not affect the outer diameter of the As a result, the small-diameter base portion 52 does not require high dimensional accuracy, and an appropriate fitting force for detachably connecting the front shaft 5 and the rear shaft 6 can be set and maintained. The productivity of shaft 6) is improved. In addition, since the outer surface shape and outer diameter of the rear barrel 6 are stable, reliable airtight performance and fitting force can be obtained when the cap 2 and the rear barrel 6 are fitted.

The first inward locking portion 63a is an annular groove 631 that can be locked with the first outward locking portion 53a, and the second inward locking portion 63b is contactable with the second outward locking portion 53b. When the front shaft 5 and the rear shaft 6 are connected, the opening of the rear shaft 6 and the stepped portion 55 are brought into contact with each other, and the first outward locking portion 53a and the annular groove 631 are in contact with each other. are engaged in the axial direction, and the second outward locking portion 53b and the pressure contact surface 632 are radially pressed against each other. As a result, the front shaft 5 and the rear shaft 6 are fitted in the proper locking position, so that a proper fitting force for detachably connecting the front shaft 5 and the rear shaft 6 can be obtained more reliably. can. Moreover, the user can be made to recognize that the front axle 5 and the rear axle 6 have been properly connected. When the front shaft 5 and the rear shaft 6 (that is, the barrel 8) are made of a material having transparency, they contain an ultraviolet absorber or a transparent ultraviolet shielding agent, which will be described later, or the front shaft 5 and the rear shaft Preferably, the surface of 6 (that is, barrel 8) is provided with a light-stabilizing layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent. As a result, even though the writing instrument 1 uses a member (barrel 8) formed of a transparent material, the handwriting formed by the writing instrument 1 does not deteriorate in appearance due to fading or browning from the initial stage. The color tone and remaining amount of ink in the writing instrument 1 can be visually recognized.

Moreover, the writing instrument 1 may be provided with a friction body 9 . It is preferable that the friction body 9 incorporates thermochromic ink therein and is provided in a part of the writing instrument capable of ejecting the thermochromic ink from the nib 3 . The structure in which the friction body 9 is provided as a part of the writing instrument 1 is, for example, a structure in which the friction body 9 is provided on the opposite side of the pen tip of the writing instrument body, or a structure in which the friction body 9 is provided on the pen tip side of the writing instrument body. and the like. The friction body can also be combined with a writing instrument that incorporates thermochromic ink therein and that can discharge the thermochromic ink from the nib 3 to form a writing instrument set. Further, the friction body 9 may be configured such that the outer peripheral surface thereof is directly gripped during friction, or the friction body is gripped via a friction body holder.

When the friction body is attached to the writing instrument 1, it can be attached to the writing instrument by fitting it to the writing instrument after molding it as a separate member, or integrally molding it to the writing instrument main body or the writing instrument member by two-color molding. When the friction body is fitted as a separate member, the number of parts can be reduced by forming the friction body into the shape of a writing instrument member such as a cap, barrel, crown, or breech plug, and directly constructing the writing instrument. Further, the friction body can be easily provided by two-color molding together with the writing instrument main body and the writing instrument member.

In the present embodiment, the elastic material constituting the friction body 9 is preferably an elastic synthetic resin (rubber, elastomer), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin. (styrene-ethylene-butylene-styrene copolymer), fluororesin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM) or a mixture of two or more rubber elastic materials, and rubber elastic material and synthetic resin. The synthetic resin having elasticity that constitutes the friction body 9 is not a high-wear elastic material (for example, an eraser), but a low-wear elastic material that produces almost no wear residue (eraser residue) during friction. As for the friction body, a writing instrument set can be obtained by combining a writing instrument and a separate friction instrument, which is a member of arbitrary shape.

The friction body 9 may be made of a mixture of polypropylene resin and a styrene-based thermoplastic elastomer, or a mixture of polypropylene resin and a polypropylene-based thermoplastic elastomer. The blending ratio of the mixture is 1:1 to 1:4 by weight, does not contain abrasives, plasticizers, and fillers, and has a durometer hardness A specified in JIS K6251 of 70° to 100°. It is made of a low-abrasion elastic material that does not contain a plasticizer and has a pencil-drawn line erasability (erasure rate) of 70% or less as defined in JIS S 6050-2002. As a result, the friction body is effective because erasable scum is less likely to occur during rubbing, and heat discoloration is excellent.

·Holding body The holding body 4 is a tubular body with both ends opened, and the holding part 41 has a flat surface and is preferably formed by injection molding of a transparent synthetic resin. In this case, it is preferable that the support contains an ultraviolet absorber or a transparent ultraviolet shielding agent, or a light stable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent is provided on the surface of the support. As a result, even though the writing instrument 1 uses a member (holding body) formed of a transparent material, the handwriting formed by the writing instrument 1 does not deteriorate in appearance due to fading or browning from the initial stage. The shape of the nib and the color tone and remaining amount of ink in the writing instrument 1 can be visually recognized.

A plurality of (here, four) first ribs 43a extending in the axial direction to which the central portion 34 of the pen tip 3 is press-fitted are formed on the inner surface of the rear end portion of the holder 4, which has a circular cross section. be done. A plurality (here, six) of second ribs extending in the axial direction and press-fitted into the holder fitting portion 58 of the front shaft 5 are formed on the outer surface of the rear end portion of the holder 4 having a circular cross section. 43b are formed at regular intervals. A communication hole formed by the second rib 43b and the holder fitting portion 58 of the front barrel 5 functions as an air circulation hole, enabling smooth ink ejection from the nib 3. As shown in FIG.

As shown in FIG. 2 or FIG. 3 , the holder 4 has a holder 41 with a substantially rectangular cross section that surrounds the front portion 33 of the pen tip 3 , and the writing section 31 extends along the front edge of the holder 4 . It protrudes forward from the portion 44 . The holding portion 41 has a flat portion on the long side of the rectangular cross section. As a result, the colorant tends to fade or brown in the conventional ink, and thus the handwriting obtained by writing also tends to fade or brown, which tends to impair the commercial value. However, according to the present invention, the holder 4 or the cap 2 contains an ultraviolet absorber or a transparent ultraviolet shielding agent, or the surface of the holder is provided with a photostable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent. Although the writing instrument 1 uses a member formed of a material having transparency, the handwriting formed by the writing instrument 1 does not deteriorate the appearance due to fading or browning from the beginning, and the shape of the nib and the inside of the writing instrument 1 are improved. The color tone and remaining amount of ink can be visually recognized.

Moreover, as shown in FIG. 2, the tip 32 of the nib 3 protrudes forward from the front edge 44 of the holder 4, and the amount of protrusion is more than 0.2 mm and less than 6.0 mm. Effectively, it is greater than 1.0 mm and less than 5.0 mm. Within the preferred range, the smaller the amount of protrusion, the more rigid and firm the feeling of writing.

A front edge 44 of the holding body 4 is provided with a chamfer or radius. In particular, it is preferable to provide chamfering or R at least at the edge on the pen tip 3 side where the pen tip 3 may come into contact. This minimizes the load on the front portion 33 of the nib 3, even though it may contact the front edge 44 of the holder 4 if the nib 3 is bent excessively. It is possible to more reliably prevent the pen tip 3 from breaking or being damaged.

As shown in FIG. 2 or 3, the front edge portion 44 of the holder 4 is formed in a substantially straight line, and the top portion 32 of the writing portion 31 is formed in a substantially straight line. The angle is substantially the same as the angle of the top portion 32 of the writing portion 31 with respect to the axis. As a result, the load on the pen tip 3 from the front edge portion 44 of the holder 4 due to excessive bending of the pen tip 3 is evenly applied to the front portion 33 of the pen tip 3, preventing the pen tip 3 from breaking or being damaged. You can definitely prevent it.

The angle of the front edge portion 44 of the holder 4 with respect to the axis refers to the angle of the portion of the angle formed by the front edge portion 44 of the holder 4 and the axis that is 90 degrees or less. "Angle with respect to the axis" refers to an angle of 90 degrees or less among the angles formed by the apex 32 and the axis. In other words, the fact that these two angles are substantially the same means that the front edge portion 44 and the top portion 32 of the holder 4 are substantially parallel. Also, these angles are set at 30 degrees or more and 90 degrees or less, preferably 45 degrees or more and 90 degrees or less.

As shown in FIG. 2, when the entire writing instrument is viewed from the direction along the extension of the short side where the writing portion 31 contacts the paper surface, the shape of the nib 3 exposed from the holder 4 is approximately parallelogram or parallelogram. Rectangular. As a result, since the shape and direction of the writing part 31 can be grasped by the shape of the front edge part 44, it is not necessary to confirm the direction only by the direction of the pen tip 3 immediately before writing, and after the pen tip 3 is exposed. , can be used for writing instantly.

Also, the color of the holder 4 may be different from the color of the pen tip 3 (that is, the ink color). This makes the orientation of the front edge portion 44 more conspicuous, and makes it easier to confirm the shape and direction of the writing portion 31 . If the pen tip 3 itself is colored in a dark color such as black and the holder 4 is colored in a bright color different from that of the pen tip 3, the orientation of the front edge portion 44 becomes even more conspicuous, and the shape of the writing portion 31 becomes more conspicuous. And it becomes easier to confirm the direction.

The structure for detachably fitting the front shaft 5 and the rear shaft 6 according to the present invention may be applied to the fitting structure for the holding body 4 and the front shaft 5 . As a result, the holder 4 and the front shaft 5 are detachably fitted together, and the holder 4 and the front shaft 5 can be easily detachably connected with an appropriate fitting force, giving the user a comfortable feeling. In addition, the user can recognize that the holder 4 and the barrel 5 are properly connected, and the pen tip can be easily replaced.

Also, the holder is not particularly limited to the illustrated structure and shape. For example, the holding member may hold the ink guiding portion and the writing portion, and at least a portion of the holding member may be a visible portion that allows the writing direction to be visually recognized. Further, the holding body may be configured to be a visual recognition portion that holds the pen tip that serves as the writing portion, has at least one ink guide portion for supplying ink to the writing portion, and allows visual confirmation of the writing direction. More specifically, the holder is a member made of transparent resin or glass that allows the user to visually recognize the writing direction. More preferably, it is a member made of transparent resin or glass having a parallel light transmittance of 70% or more, and has a wide visible portion on the front and a shaft portion on the rear. A member such as resin or glass having a parallel light transmittance of less than 30% is not preferable because the writing direction cannot be clearly seen. Examples of resins satisfying these physical properties include styrene-isoprene resins, ionomer resins, SBR-PP blend resins, acrylic resins, nylon resins, and polymethylpentene.

In addition, the ink described later may be put into practical use by filling a writing implement such as a ballpoint pen with a tip (pen point) attached to the writing tip.

When a ball-point pen is filled with ink, which will be described later, the structure and shape of the ball-point pen itself are not particularly limited. A structure that supplies ink, a structure in which ink is stored directly inside the barrel, and a comb groove-like ink flow rate adjusting member or an ink flow rate adjusting member consisting of a fiber bundle is interposed, and an ink storage tube filled with ink in the barrel. The ink storage tube communicates with a tip having a ball attached to the tip thereof, and a liquid plug for backflow prevention is in close contact with the end face of the ink.

To explain the ball-point pen tip in more detail, the tip is formed by cutting a metal material with a drill or the like, in which a ball is held in a ball-holding portion in which the vicinity of the tip of a metal pipe is pressed and deformed inward from the outer surface. A chip that holds a ball in a ball holding portion, a chip that has a resin ball receiving seat inside a metal or plastic chip, or a spring that urges the ball held by the chip forward. etc. can be applied.
The ball can be made of cemented carbide, stainless steel, ruby, ceramic, resin, rubber, etc., and has a diameter of about 0.2 to 3 mm.
Note that the writing instrument to be filled with the ink of the present invention includes one having a rolling mechanism such as a roller at the tip of the writing section for forming a handwriting by a rolling motion similar to that of a ball.

For the ink storage tube that stores ink, for example, a transparent molded body made of thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon is used.
The transparency of the ink storage tube includes colored transparent, semi-transparent, and colored semi-transparent so that the ink color, remaining amount of ink, etc. can be checked.
A tip is connected to the ink storage tube directly or via a connecting member to form a refill, and the refill is accommodated in a transparent barrel to form a writing implement.
In addition, a writing implement can be constructed by directly filling ink into a transparent barrel having a tip attached to the tip thereof.
The transparency of the shaft cylinder includes colored transparent, translucent, and colored semi-transparent, and the ink color, remaining amount of ink, etc. can be checked.

The rear end of the ink contained in the ink containing tube or barrel can be filled with an ink backflow preventive.
The ink backflow preventive composition comprises a non-volatile liquid or a low-volatility liquid.
Specifically, petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, Examples include polyether-modified silicone oil and fatty acid-modified silicone oil, and one or more of them can be used in combination.

It is preferable to add a gelling agent to the non-volatile liquid and/or the hardly volatile liquid to increase the viscosity to a suitable viscosity. , swelling mica, hydrophobized bentonite, montmorillonite, and other clay-based thickeners, magnesium stearate, calcium stearate, aluminum stearate, zinc stearate, and other fatty acid metal soaps, tribenzylidene sorbitol, fatty acid amides, amide-modified Examples include polyethylene wax, hydrogenated castor oil, dextrin-based compounds such as fatty acid dextrin, and cellulose-based compounds.
Further, the liquid ink backflow preventive composition and the solid ink backflow preventer can be used together.
The shape of the ball-point pen is not limited to the one described above, and it may be a twin-type writing instrument having nibs of different shapes or nibs that draw out inks of different tones. .

The reversible thermochromic material used as the colorant is a conventionally known (a) electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) the temperature at which the color reaction of both of them occurs. It is effective to encapsulate a reversible thermochromic composition containing at least the three essential components of the reaction medium that determines the Those described in JP-B-51-44706, JP-B-51-44707, JP-B-1-29398, etc. can be used.
The above changes color before and after a predetermined temperature (color change point) as a boundary, exhibits a decolored state in a temperature range above the complete decoloring temperature, and a colored state in a temperature range below the complete decoloring temperature. Only one particular state exists in the realm. That is, the other state is maintained as long as the heat or cold required to develop that state is applied, but returns to the state exhibited at room temperature when the heat or cold is no longer applied, hysteresis. It has a relatively narrow characteristic (ΔH _A =1 to 7° C.) (see FIG. 7).

Moreover, the large hysteresis characteristics (ΔH _B =8 to 50° C. ), that is, the shape of the curve plotting the change in color density due to temperature change is when the temperature is raised from the lower temperature side than the discoloration temperature range, and on the contrary when it is lowered from the higher temperature side than the discoloration temperature range. The color change occurs along a significantly different route, and the color development state in a low temperature range below the complete color development temperature (t ₁ ), or the color disappearance state in a high temperature range above the complete color disappearance temperature (t ₄ ) is a specific temperature range. A heat-erasable microcapsule pigment that can memorize and retain color in a [temperature range between t ₂ and t ₃ (substantially two-phase retention temperature range)] can also be applied (see FIG. 8).
As heat-erasable microcapsule pigments capable of storing and retaining colors, those using an ester compound represented by the following general formula (1) as component (c) have a wide hysteresis width (40 ~70°C) and discolors, so it is suitable.
In order to allow only a specific one of the states before and after the discoloration to exist at room temperature, the hysteresis width is 40 to 70°C, preferably 50 to 70°C, more preferably 60 to 70°C. The color temperature (t ₄ ) is 45° C. or higher, preferably 50° C. or higher, and the color development start temperature (t ₂ ) is 0° C. or lower, preferably -5° C. or lower.

The ester compound is an ester compound composed of an alcohol compound having two aromatic rings in the molecule and a saturated or unsaturated fatty acid having 4 or more carbon atoms.
In the formula, R represents an alkyl group or alkenyl group having 4 or more carbon atoms, preferably 6 carbon atoms.
to 20 alkyl groups, more preferably 8 to 18 carbon atoms.
Specific examples of the compounds include 4-benzyloxyphenylethyl butanoate, 4-benzyloxyphenylethyl pentanoate, 4-benzyloxyphenylethyl hexanoate, 4-benzyloxyphenylethyl heptanoate, and octanoic acid. -4-benzyloxyphenylethyl, -4-benzyloxyphenylethyl nonanoate, -4-benzyloxyphenylethyl decanoate, -4-benzyloxyphenylethyl undecanoate, -4-benzyloxyphenylethyl dodecanoate, tridecanoic acid -4-benzyloxyphenylethyl, 4-benzyloxyphenylethyl tetradecanoate, 4-benzyloxyphenylethyl pentadecanoate, 4-benzyloxyphenylethyl hexadecanoate, 4-benzyloxyphenylethyl heptadecanoate, octadecanoic acid -4-benzyloxyphenylethyl, -4-benzyloxyphenylethyl nonadecanate, -4-benzyloxyphenylethyl eicosanoate, -4-benzyloxyphenylethyl tricosanoate, -4-benzyloxyphenylethyl tetracosanoate, pentacosanoic acid -4-benzyloxyphenylethyl, 4-benzyloxyphenylethyl hexacosanoate, 4-benzyloxyphenylethyl heptacosanoate, 4-benzyloxyphenylethyl octacosanoate, 4-benzyloxyphenylethyl nonacosanoate, triacontane Examples include 4-benzyloxyphenylethyl acid and 4-benzyloxyphenylethyl hentriacontanoate.

Furthermore, as a heat-color-developing microcapsule pigment, a system using a specific alkoxyphenol compound having a linear or side-chain alkyl group having 3 to 18 carbon atoms as an electron-accepting compound (JP-A-11-129623, JP-A-11-129623, JP-A-11-129623, JP-A-11-5973), a system applying a specific hydroxybenzoic acid ester (JP-A-2001-105732), a system applying a gallic acid ester, etc. (JP-B-51-44706, JP-A-2003-253149 No. 2002-200010), etc. (see FIG. 9).
Here, a colorant such as a non-thermochromic dye or pigment is blended in the reversible thermochromic microcapsule pigment or ink to cause a tautomatic color change from colored (1) to colored (2). It can also be configured to exhibit

The microcapsule pigments may be in the form of circular or non-circular cross-sections.
The average particle size of the microcapsule pigment is 0.5-5.0 μm, preferably 1-4 μm, more preferably 1-3 μm.
If the average particle size exceeds 5.0 µm, the ink flowability tends to be lowered and the adhesion to the writing surface tends to be lowered. On the other hand, if the average particle size is less than 0.5 μm, it becomes difficult to exhibit high density color development.
In addition, when the ratio of the reversible thermochromic composition to the wall film increases, the thickness of the wall film becomes too thin, causing a decrease in resistance to pressure and heat, and conversely, the ratio of the wall film to the reversible thermochromic composition As the weight ratio increases, the color density and vividness of the color development are inevitably lowered.

Here, the average particle size of the microcapsule pigment is the arithmetic average value of the maximum particle size of each particle measured by image analysis of the observed image with a digital microscope in accordance with JIS Z 8827-1:2008. . For image analysis, for example, image analysis type particle size distribution measurement software "Mac-View" manufactured by Mountech can be used.

For the measurement of the average particle size, the area of the particles is determined using the image analysis type particle size distribution measurement software "MacView" manufactured by Mountec, Inc., and the projected area circle equivalent diameter (Heywood diameter) is calculated from the area of the particle area. , is the value measured as the average particle diameter of particles equivalent to a sphere of equal volume based on that value. In addition, when the particle size of all particles or most of the particles exceeds 0.2 μm, a particle size distribution measuring device (manufactured by Beckman Coulter, Inc., product name: Multisizer 4e) is used to measure equivolumetric spheres by the Coulter method. It is also possible to measure as the average particle size of the particles.

The reversible thermochromic microcapsule pigment can be blended in an amount of 2 to 50% by weight, preferably 3 to 40% by weight, more preferably 4 to 30% by weight, based on the total amount of the ink.
If it is less than 2% by weight, the color density is insufficient, and if it exceeds 50% by weight, the ink flowability is lowered and the writability is impaired.

For the microencapsulation of the reversible thermochromic composition, known means such as an interfacial polymerization method, an interfacial polycondensation method, an in-situ polymerization method, and a coacervate method can be applied. In order to obtain a microcapsule pigment having a non-circular cross-sectional shape, it is effective to apply an interfacial polymerization method or an interfacial polycondensation method in which aggregation and coalescence are unlikely to occur.

Examples of the photochromic organic material include benzopyran compounds such as 6-methoxy-2,2-diphenyl-2H-1-benzopyran, and naphthopyran compounds such as 3,3-diphenyl-3H-naphtho[2,1-b]pyran. , spiropyran compounds such as 1,3,3-trimethyl-indolino-6'-nitrobenzospiropyran, 1,3-dihydro-1,3,3-trimethyl-6'-(1-piperidinyl)-spiro [2H- indole-2,3′-[3H]naphtho[2,1-b][1,4]oxazine], 1,3-dihydro-1,3,3,4,5-pentamethyl-spiro[2H-indole- 2,3′-[3H]naphtho[2,1-b][1,4]oxazine], 1-(2,4-dichlorobenzyl)-3,3-dimethyl-5,6-dichlorospiro [indoline- Examples include spirooxazine compounds such as 2,3'-[3H]naphtho[2,1-b][1,4]oxazine] and diarylethene compounds.
The photochromic organic material can also be used by encapsulating it in the aforementioned microcapsules.

As the dyes, dyes used in oil-based inks include, for example, organic solvent-soluble dyes classified as solvent dyes in the Color Index.
Acid dyes, basic dyes, and direct dyes that are soluble in an aqueous medium can all be used as dyes for water-based inks.
As the pigment, a fluorescent pigment in the form of synthetic resin fine particles, in which various fluorescent dyes are dissolved in a resin matrix, can be used.
If desired, non-fluorescent pigments, pearl pigments, metal powder pigments, luminous pigments, titanium dioxide, silica, white pigments such as calcium carbonate, fragrances, capsule pigments encapsulating fragrances, and the like can also be used in combination.
The dye, fluorescent pigment, or photochromic organic material is used in an amount of 1 to 25% by weight, preferably 2 to 15% by weight, based on the total amount of the ink.

The ink used in the present invention is effectively one in which a colorant is dissolved or dispersed in a solvent.
Specific examples of the ink include a shear-thinning ink containing a shear-thinning agent, and a cohesive ink in which a pigment or transparent metallic luster pigment is suspended in a loosely agglomerated state with a water-soluble polymer flocculant. low-viscosity ink having a viscosity of about several mPa·s.

As the solvent, in the case of oil-based ink, an organic solvent is used, and in the case of water-based ink, water and, if necessary, a water-soluble organic solvent are used.
As the organic solvent used for the oil-based ink, conventional general-purpose solvents can be used, and used in the range of 40 to 80% by weight in the ink.
Examples of the organic solvent include benzyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, benzyl glycol, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monoethyl ether, diethylene glycol monophenyl ether, propylene glycol mono Ethyl ether, propylene glycol monophenyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monophenyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monophenyl ether, methyl lactate, ethyl lactate, γ - Butyrolactone and the like can be exemplified.

Further, when a solvent having a vapor pressure of 5.0 to 50 mmHg at 20° C., which is easily volatilized, is used as the main solvent, the handwriting is excellent in drying property.
Organic solvents having a vapor pressure of 5.0 to 50 mmHg (20° C.) include ethyl alcohol (45), n-propyl alcohol (14.5), isopropyl alcohol (32.4), n-butyl alcohol (5.5 ), isobutyl alcohol (8.9), sec-butyl alcohol (12.7), tert-butyl alcohol (30.6), alcohol-based organic solvents such as tert-amyl alcohol (13.0),
glycol ether organic solvents such as ethylene glycol monomethyl ether (8.5), ethylene glycol diethyl ether (9.7), ethylene glycol monoisopropyl ether (6.0), propylene glycol monomethyl ether (7.6);
n-heptane (35.0), n-octane (11.0), isooctane (41.0), methylcyclohexane (37.0), ethylcyclohexane (10.0), toluene (24.0), xylene ( 5.0 to 6.0), hydrocarbon-based organic solvents such as ethylbenzene (7.1),
ketone organic solvents such as methyl isobutyl ketone (16.0), methyl n-propyl ketone (12.0), methyl n-butyl ketone (12.0), di-n-propyl ketone (5.2);
n-butyl formate (22.0), isobutyl formate (33.0), n-propyl acetate (25.0), isopropyl acetate (48.0), n-butyl acetate (8.4), isobutyl acetate (13 .0), ethyl propionate (28.0), n-butyl propionate (45.0), methyl butyrate (25.0), and ethyl butyrate (11.0).
The numbers in parentheses indicate the vapor pressure of each organic solvent at 20°C.

In the case of water-based ink using water as a solvent, a water-soluble organic solvent compatible with water may be added.
Examples of the water-soluble organic solvent include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, and ethylene glycol monomethyl. Ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone etc.

Resins include ketone resins, ketone-formaldehyde resins, amide resins, alkyd resins, rosin-modified resins, rosin-modified phenolic resins, phenolic resins, xylene resins, polyvinylpyrrolidone, α- and β-pinene-phenol polycondensation resins, polyvinyl butyral resins. , acrylic resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, dextrin, and the like can also be used, and can be used to impart adhesion and viscosity to paper surfaces.

Further, a shear thinning agent may be added as necessary.
By adding the shear thinning agent, it is possible to suppress aggregation and sedimentation of the colorant, and to suppress bleeding of handwriting.
Furthermore, when the writing instrument to be filled with ink is in the form of a ballpoint pen, it is possible to prevent ink from leaking out from the gap between the ball and the tip when not in use, or to prevent the ink from leaking when the writing tip is left facing upward (upright state). Backflow can be prevented.
The viscosity of the ink to which the shear thinning agent is added is 100 mPa s or more at a shear rate of 3.84 S ⁻¹ measured by an E-type viscometer at 20° C. in the case of an oil-based ink. In addition, the shear thinning index is preferably 0.3 to 0.9, and in the case of water-based ink, the ink viscosity at a shear rate of 3.84 S ^-1 by an E-type rotational viscometer at 20 ° C. is 20 to It preferably exhibits 300 mPa·s and a shear thinning index of 0.1 to 0.9.
By exhibiting the aforementioned viscosity range and shear thinning index, it is possible to further prevent ink leakage and ink backflow.
The shear thinning index (n) is obtained from the empirical formula T = Kj ⁿ (K is a non-Newtonian viscosity coefficient) obtained from rheological measurements with a viscometer such as the shear stress value (T) and the shear rate value (j). It is a value calculated by fitting.

In the case of oil-based ink using an organic solvent as a solvent, crosslinked acrylic resin, emulsion type of crosslinked acrylic resin, non-crosslinked acrylic resin, crosslinked N-vinylcarboxylic acid amide polymer or copolymer, non-crosslinked type N-vinylcarboxylic acid amide polymer or copolymer, hydrogenated castor oil, fatty acid amide wax, waxes such as polyethylene oxide wax, stearic acid, palmitic acid, octylic acid, fatty acid metal salts such as aluminum salts of lauric acid , dibenzylidene sorbitol, N-acyl amino acid compounds, smectite inorganic compounds, montmorillonite inorganic compounds, bentonite inorganic compounds, hectorite inorganic compounds, silica and the like.
In the case of water-based ink using water as a solvent, xanthan gum, welan gum, succinoglycan (average molecular weight of about 1 million to 8 million), which is an organic acid-modified heteropolysaccharide composed of glucose and galactose as constituent monosaccharides, alkasi gum, guar gum, Locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, polymers with a molecular weight of 100,000 to 150,000 mainly composed of alkyl esters of methacrylic acid, glucomannan, gelation extracted from seaweed such as agar and carrageenan thickening polysaccharide, benzylidene sorbitol and benzylidene xylitol or their derivatives, cross-linkable acrylic acid polymer, inorganic fine particles, polyglycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene castor oil , polyoxyethylene lanolin, lanolin alcohol, beeswax derivatives, polyoxyethylene alkyl ethers, polyoxypropylene alkyl ethers, polyoxyethylene alkylphenyl ethers, nonionic surfactants with an HLB value of 8 to 12 such as fatty acid amides, dialkyl or Salts of dialkenyl sulfosuccinic acid. Examples include a mixture of N-alkyl-2-pyrrolidone and an anionic surfactant, and a mixture of polyvinyl alcohol and acrylic resin.
The shear thinning agent can be used in combination, and the polymer can be used as a resin.

When the ink of the present invention is filled in a ballpoint pen and used, a higher fatty acid such as oleic acid, a nonionic surfactant having a long-chain alkyl group, a polyether-modified silicone oil, a thiophosphite tri(alkoxycarbonylmethyl ester) or Thiophosphite triesters such as thiophosphite tri(alkoxycarbonylethyl ester), phosphoric acid monoesters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, phosphorus of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers It is preferable to add a lubricant such as an acid diester or a metal salt, ammonium salt, amine salt or alkanolamine salt thereof to impart an anti-wear effect to the ball seat.

In the case of water-based inks, if necessary, inorganic salts such as sodium carbonate, sodium phosphate, and sodium acetate, pH adjusters such as organic basic compounds such as water-soluble amine compounds, benzotriazole, tolyltriazole, and dicyclohexylammonium nitride. Rust inhibitors such as light, diisopropylammonium nitrite, saponin, phenolic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl parahydroxybenzoate, 2,3, Preservatives or antifungal agents such as 5,6-tetrachloro-4-(methylsulfonyl)pyridine, urea, nonionic surfactants, reduced or non-reduced starch hydrolysates, oligosaccharides such as trehalose, sucrose, cyclo Wetting agents such as dextrin, glucose, dextrin, sorbit, mannitol, sodium pyrophosphate, etc., antifoaming agents, dispersing agents, fluorine surfactants and nonionic surfactants that improve ink permeability can be used. good.

In the present invention, the ink storage tube and/or barrel are provided with a photostable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent, or containing an ultraviolet absorbing agent or a transparent ultraviolet shielding agent.
Specifically, a refill containing ink in a transparent ink storage tube is accommodated in a transparent barrel, and the barrel contains an ultraviolet absorber or a transparent ultraviolet shielding agent, or contains an ultraviolet absorber or a transparent ink. A configuration in which a light stable layer containing an ultraviolet shielding agent is provided, or a refill in which ink is stored in a transparent ink storage tube is stored in a transparent shaft cylinder, and the ink storage tube contains an ultraviolet absorber or a transparent ultraviolet ray. It is a structure in which a light-stabilizing layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent is provided on the surface of a barrel containing a shielding agent or containing ink.
When the transparent ink storage tube and the transparent barrel are used together, both the ink storage tube and the barrel contain an ultraviolet absorber or a transparent ultraviolet shielding agent, or contain an ultraviolet absorbing agent or a transparent ultraviolet shielding agent. A configuration in which a photostable layer is provided may be used.
In the structure of the writing instrument described above, when a transparent cap that covers the writing tip is provided, the cap contains an ultraviolet absorber or a transparent ultraviolet shielding agent, or the cap surface contains an ultraviolet absorber or a transparent ultraviolet shielding agent. A stabilizing layer is preferably provided.

As the ultraviolet absorber,
2,4-hydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone,
2,2′-dihydroxy-4,4′-dimethoxybenzophenone,
2,2′,4,4′-tetrahydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone-5-sulfonic acid,
2-hydroxy-4-octoxybenzophenone,
bis-(2-methoxy-4-hydroxy-5-benzoylphenyl)-methane 2-[2'-hydroxy-3'-5'-di-t-amylphenyl]-benzophenone,
2-hydroxy-4-dodecyloxy-benzophenone [trade name: Seesorb 103, manufactured by Shipro Kasei Co., Ltd.],
2-hydroxy-4-octadecyloxybenzophenone,
2,2′-dihydroxy-4-methoxybenzophenone,
2-hydroxy-4-benzyloxybenzophenone,
Benzophenone UV absorbers such as 2-[2'-hydroxy-3'-5'-di-t-amylphenyl]-benzophenone.

phenyl salicylate,
para-t-butylphenyl salicylate,
para-octylphenyl salicylate,
2-4-di-t-butylphenyl-4-hydroxybenzoate,
1-hydroxybenzoate,
1-hydroxy-3-t-butyl-benzoate,
1-hydroxy-3-t-octylbenzoate,
salicylic acid-based UV absorbers such as resorcinol monobenzoate;

ethyl-2-cyano-3,3'-diphenyl acrylate,
2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate,
Cyanoacrylate UV absorbers such as 2-ethylhexyl-2-cyano-3-phenylcinnate.

2-[5-t-butyl-2-hydroxyphenyl]-benzotriazole [trade name: Tinuvin-PS, manufactured by Ciba-Geigy],
2-[5-methyl-2-hydroxyphenyl]-benzotriazole,
2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H benzotriazole,
2-[3,5-di-t-butyl-2-hydroxyphenyl]-benzotriazole,
2-[3-t-butyl-5-methyl-2-hydroxyphenyl]-5-chlorobenzotriazole,
2-[3,5-di-t-butyl-2-hydroxyphenyl]-5-chlorobenzotriazole,
2-[3,5-di-t-amyl-2-hydroxyphenyl]-benzotriazole [trade name: Tinuvin 328, manufactured by Ciba-Geigy],
methyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate-polyethylene glycol molecular weight 300 [trade name: Tinuvin 1130, manufactured by Ciba-Geigy],
2-[3-dodecyl-5-methyl-2-hydroxyphenyl]benzotriazole,
methyl-3-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionate-polyethylene glycol molecular weight 300,
2-[3-t-butyl-5-propyloctylate-2-hydroxyphenyl]-5-chlorobenzotriazole,
2-[2-hydroxyphenyl-3,5-di-(1,1′-dimethylbenzyl)phenyl]-2H-benzotriazole,
2-[2-hydroxy-5-t-octylphenyl]-2H-benzotriazole,
2-[3-t-butyl-5-octyloxycarbonylethyl-2-hydroxyphenyl]-benzotriazole [trade name: Tinuvin 384, manufactured by Ciba-Geigy],
2-[2-hydroxy-5-tetraoctylphenyl]-benzotriazole,
2-[2-hydroxy-4-octoxy-phenyl]-benzotriazole,
2-[2′-hydroxy-3′-(3″4″5″6″-tetrahydrophthalimidomethyl)-5′-methylphenyl]-benzotriazole,
benzotriazole-based UV absorbers such as 2-(2-hydroxy-5-t-butylphenyl)-benzotriazole;

ethanediamide-N-(2-ethoxyphenyl)-N'-(4-isododecylphenyl),
2,2,4,4-tetramethyl-20-(β-lauryl-oxycarbonyl)-ethyl-7-oxa-3,20-diazodispiro(5,1,11,2)heneichoate-21-one and the like Examples include oxalic acid anilide-based ultraviolet absorbers and the like.

Examples of the transparent light shielding agent include transparent metallic luster pigments obtained by coating the surface of a core material selected from natural mica, synthetic mica, glass, and alumina with a metal oxide.
The transparent metallic luster pigment has both a light absorption (or light reflection) function and a light transmission function. It is possible to visually check the color tone and remaining amount of the ink stored inside.

Furthermore, a light stabilizer can be used together with the ultraviolet absorber or the transparent light shielding agent.
Examples of the light stabilizer include antioxidants, anti-aging agents, singlet oxygen quenchers, superoxide anion quenchers, ozone quenchers, visible light absorbers, and infrared absorbers.
Of these, hindered amine photo-stabilizers are preferably used. Tetramethyl-4-piperidyl)imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl)imino] [trade name: Sumisolv 500, manufactured by Sumitomo Chemical Co., Ltd.], 1,2, Tetra(2,2,6,6-tetramethyl-4-piperidyl) 3,4-butanetetracarboxylic acid (manufactured by Adeka Argus), poly[[6-1,1,3,3-tetramethylbutyl)imino -1,3,5-triazine-2,4-diyl](2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene [(2,2,6,6-tetramethyl-4- piperidyl)imino] (trade name: Tinuvin 944-LD, manufactured by Ciba-Geigy), dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate ( Trade name: Tinuvin 622LD, manufactured by Ciba-Geigy), 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentatyl) -4-piperidyl) (trade name: Tinuvin 144, manufactured by Ciba-Geigy), N,N,-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2, 6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate [trade name: Sanol LS770, manufactured by Sankyo Co., Ltd.], bis(N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate [trade name: Sanol LS292, manufactured by Sankyo Co., Ltd.], 4-benzoyloxy- 2,2,6,6-tetramethyl-4-piperidine [trade name: Sanol LS-744, manufactured by Sankyo Co., Ltd.], 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1 , 3,8-triazaspiro[4.5]decane-2,4-dione [trade name: Sanol LS-440, manufactured by Sankyo Co., Ltd.], 1-[2-[3-(3,5-di-t -butyl-4-hydroxyphenyl)propionyloxy]ethyl]-4-[3-3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine [ Sankyo Co., Ltd.], 2,2,4,4-tetramethyl-20-(β-lauryl-oxycarbonyl)-ethyl-7-oxa-3,20-diazadispio (5,1,11,2 ) Heneicosan-21-one (trade name: Sanduvor 305, manufactured by Sandu), [N-(2,2,6,6-tetramethyl-4-piperidyl)-β-alanine] dodecyl ester, myristyl ester mixture (trade name : Sanduvor 3052, manufactured by Sando Corporation), 5-norbornene-2,3-dicarboxylic acid bis(2,2,6,6-tetramethyl-4-piperidyl) ester, 5-norbornene-2,3-dicarboxylic acid bis(N-methyl-2,2,6,6-tetramethyl-4-piperidyl) ester and the like.

Examples are described below. In addition, the part in an Example shows a mass part.
Example 1
Preparation of water-based ink composition for ballpoint pen Red acid dye [manufactured by Hodogaya Chemical Co., Ltd., trade name: Eosin] 4.0 parts, glycerin 10.0 parts, ethylene glycol 20.0 parts, xanthan gum (Sansho Co., Ltd.) 0.3 parts of phenol, 0.3 parts of phenol, and 65.4 parts of water were mixed and stirred to obtain an aqueous ink composition for ballpoint pens.

Preparation of Writing Instruments 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol (manufactured by BASF Japan Ltd., trade name: Tinuvin 328, UV absorber)0. 25 parts and 0.25 parts of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate [manufactured by BASF Japan Ltd., trade name: Tinuvin 770, light stabilizer] mixed inner diameter 4.4 mm 0.95 g of the ink was filled in a polypropylene pipe of No. and connected to a ball-point pen tip through a resin holder to obtain a ball-point pen refill.
The tip of the ball-point pen is formed by pressing and deforming the vicinity of the tip of a metal pipe inward from the outer surface, and holding a stainless steel ball with a diameter of 0.5 mm at the tip of the tip.
Next, after filling a viscoelastic ink backflow preventer (liquid plug) mainly composed of polybutene from the rear part of the polypropylene pipe, a barrel, a mouthpiece, a tail plug, and a cap with a rubber seal inside are assembled. I got a ballpoint pen.

Example 2
Preparation of Water-Based Ink Composition for Marking Pen Pink fluorescent pigment dispersion [manufactured by Nippon Shoryo Kagaku Co., Ltd., trade name: Lumicol NKW-3907. E40, pigment content 33.5%] 40.0 parts, glycerin 10.0 parts, triethanolamine 0.5 parts, phenol 0.3 parts, preservative [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R- 150] and 48.7 parts of water were mixed and stirred to obtain a water-based ink composition for marking pens.

Preparation of Writing Instrument An ink occluding body made of polyester sliver covered with a synthetic resin film is impregnated with the ink, and the ink occluding body is housed in a barrel made of opaque polypropylene resin.
The pen body attached to the front end of the front shaft includes a pen tip that serves as a writing part, and a holding body that holds the pen tip and has at least one ink guide part for supplying ink to the writing part, It has a relay core for supplying the ink contained in the writing instrument main body to the ink guiding portion provided in the holding body, and the holding body serves as a visual recognition part for visually recognizing the writing direction.
2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol (manufactured by BASF Japan Ltd., trade name: Tinuvin 328, UV absorber) 0.25 parts and A cap made of polypropylene resin mixed with 0.25 parts of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate [manufactured by BASF Japan Ltd., trade name: Tinuvin 770, light stabilizer] is assembled. I got a marking pen.

Example 3
Preparation of Water-Based Ink Composition for Marking Pen Yellow fluorescent pigment dispersion [manufactured by Nippon Shoryo Kagaku Co., Ltd., trade name: Lumicol NKW-3905. E, pigment content 33.5%] 40.0 parts, glycerin 10.0 parts, triethanolamine 0.5 parts, phenol 0.3 parts, preservative [manufactured by Hokuko Chemical Co., Ltd., trade name: Hokuside R- 150] and 48.7 parts of water were mixed and stirred to obtain a water-based ink composition for marking pens.

Preparation of Writing Instruments 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol (manufactured by BASF Japan Ltd., trade name: Tinuvin 328, UV absorber)0. 25 parts and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate [manufactured by BASF Japan Ltd., trade name: Tinuvin 770, light stabilizer] 0.25 parts polypropylene resin mixed It is assembled using a barrel, an inner cap, and a cap made of polycarbonate resin. A marking pen was obtained by housing the ink in a straight liquid state in a barrel, providing a resin-processed pen tip made of polyester fiber at the tip of the barrel, and assembling a cap having an inner cap inside to a writing instrument main body.
A comb groove-shaped ink flow control member is provided at the rear portion of the nib inside the barrel.

Example 4
Preparation of reversible thermochromic microcapsule pigment (A) 4.5 parts of 2-(2-chloroanilino)-6-di-n-butylaminofluorane as component (B) 1,1-bis(4' as component -Hydroxyphenyl)n-decane 3.0 parts, 2,2-bis(4'-hydroxyphenyl)hexafluoropropane 5.0 parts, component (c) n-butyl stearate 40.0 parts, palmitic acid n - A reversible thermochromic composition consisting of 10.0 parts of butyl was uniformly heated and dissolved, and 30.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 40.0 parts of a co-solvent were mixed into 8 parts. % polyvinyl alcohol aqueous solution to form fine droplets, and after stirring at 65°C for about 1 hour, 2.5 parts of a water-soluble aliphatic modified amine is added, and stirring is continued at 90°C for 5 hours. A reversible thermochromic microcapsule pigment suspension was obtained.
A reversible thermochromic microcapsule pigment was isolated from the suspension by centrifugation.
The microcapsule pigment turned from black to colorless above about 23°C and turned black again when cooled to below 15°C.

Preparation of Reversible Thermochromic Ink Composition 25.0 parts of the microcapsule pigment, 0.2 parts of succinoglycan (shear thinning agent), 0.5 parts of triethanolamine, 5.5 parts of urea, 7 parts of glycerin. 5 parts, 0.5 parts of phosphate ester surfactant (lubricant), 0.2 parts of antifoaming agent, 1,2-benzthiazolin-3-one [manufactured by Avecia Co., Ltd., trade name: Proxel XL- 2. Antiseptic] 0.1 part and 60.5 parts of water were mixed and stirred to prepare a reversible thermochromic ink.

Preparation of Writing Instruments 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol (manufactured by BASF Japan Ltd., trade name: Tinuvin 328, UV absorber)0. 25 parts and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate [manufactured by BASF Japan Ltd., trade name: Tinuvin 770, light stabilizer) mixed 0.25 parts inner diameter 4.4 mm 0.95 g of the ink was filled in a polypropylene pipe, and connected to a ball-point pen tip via a resin holder.
The tip of the ball-point pen is formed by pressing and deforming the vicinity of the tip of a metal pipe inward from the outer surface, and holding a stainless steel ball with a diameter of 0.7 mm at the tip of the tip, and the ball is a spring. The one that was urged forward by the body was used.
Next, from the rear portion of the polypropylene pipe, a viscoelastic ink backflow prevention member (liquid plug) containing polybutene as a main component is filled, and a tail plug is fitted to the rear portion of the pipe, followed by a front barrel made of polycarbonate resin. After assembling the cylinder and the rear barrel cylinder, performing deaeration treatment by centrifugal treatment, a cap was fitted to obtain a ball-point pen.

Example 5
Preparation of Writing Instrument 0.95 g of the reversible thermochromic ink composition obtained in Example 4 was filled in a polypropylene pipe having an inner diameter of 4.4 mm, and connected to a ball-point pen tip via a resin holder.
The tip of the ball-point pen is formed by pressing and deforming the vicinity of the tip of a metal pipe inward from the outer surface, and holding a stainless steel ball with a diameter of 0.7 mm at the tip of the tip, and the ball is a spring. The one that was urged forward by the body was used.
Next, from the rear portion of the polypropylene pipe, a viscoelastic ink backflow prevention member (liquid plug) containing polybutene as a main component is filled, and a tail plug is fitted to the rear portion of the pipe to form a 2-[2-hydroxy -3,5-Bis (α, α-dimethylbenzyl) phenyl]-2H-benzotriazole (manufactured by BASF Japan Ltd., trade name: Tinuvin 234, UV absorber) made of polycarbonate resin mixed with 0.5 parts Assemble using front barrel and rear barrel. After the front barrel and the rear barrel were assembled, degassing was performed by centrifugal treatment, a cap was fitted, and a ball-point pen was obtained.

Example 6
Preparation of writing instrument The reversible thermochromic ink composition obtained in Example 4 was mixed with 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol [BASF Japan Ltd. manufactured by BASF Japan Ltd., trade name: Tinuvin 328, UV absorber] 0.25 parts and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate [manufactured by BASF Japan Ltd., trade name: Tinuvin 770, Hikari Stabilizer) 0.95 g was filled in a polypropylene pipe having an inner diameter of 4.4 mm mixed with 0.25 part of the mixture, and connected to a ball-point pen tip via a resin holder.
The tip of the ball-point pen is formed by pressing and deforming the vicinity of the tip of a metal pipe inward from the outer surface, and holding a stainless steel ball with a diameter of 0.7 mm at the tip of the tip, and the ball is a spring. The one that was urged forward by the body was used.
Next, a viscoelastic ink backflow prevention member (liquid plug) containing polybutene as a main component was filled from the rear portion of the polypropylene pipe, and a tail plug was fitted to the rear portion of the pipe.
Furthermore, 50 parts of acrylic polyol resin (solid content: 50%), 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1- Dimethylpropyl) phenol (tinuvin 328, manufactured by BASF Japan, UV absorber) 1.0 parts, xylene 60 parts, hexamethylene diisocyanate curing agent 10 parts Ink was spray-coated and heat-treated at 70 ° C. for 30 minutes. After that, it was assembled together with the pipe, subjected to centrifugal treatment for degassing, and fitted with a cap to obtain a ball-point pen.

Example 7
Preparation of photochromic microcapsule pigment Organic photochromic compound [spironaphthoxazine compound [manufactured by Recording Materials Research Institute, trade name: Sunny Color Pink] 2.0 parts, styrene-α-methylstyrene copolymer [Rika Hercules Co., Ltd., product name: Pikolastic A5, weight average molecular weight 317] 45.0 parts of a photochromic material is uniformly heated and dissolved, and 20.0 parts of an aromatic polyvalent isocyanate prepolymer is used as a film material. A solution mixed with 20.0 parts of a co-solvent was emulsified and dispersed in a 6% polyvinyl alcohol aqueous solution to form fine droplets, and reacted at 70° C. for 1 hour. Subsequently, the liquid temperature was maintained at 90° C. and stirring was continued for 3 hours to obtain a photochromic microcapsule pigment suspension.
A photochromic microcapsule pigment was isolated from the suspension by centrifugation.
The microcapsule pigment was white before exposure to sunlight, but turned pink upon exposure to sunlight. After that, when it was left in a room for a while, the pink color disappeared and returned to the original white color. This color change could be repeated.

Preparation of photochromic ink composition 25.0 parts of the microcapsule pigment, 0.2 parts of λ-carrageenan, 0.5 parts of triethanolamine, 15.0 parts of diethylene glycol, phosphate surfactant (lubricant) 0.5 parts, 0.2 parts of antifoaming agent, 1,2-benzthiazolin-3-one [manufactured by Avecia Co., Ltd., trade name: Proxel XL-2, preservative] 0.1 parts, 58.5 parts of water The parts were mixed and stirred to prepare a photochromic ink composition.

Preparation of Writing Instrument 0.95 g of the photochromic ink was filled in a polypropylene pipe having an inner diameter of 4.4 mm, and connected to a ball-point pen tip via a resin holder. The tip of the ball-point pen is formed by pressing and deforming the vicinity of the tip of a metal pipe inward from the outer surface, and holding a stainless steel ball with a diameter of 1.0 mm at the tip of the tip, and the ball is a spring. The one that was urged forward by the body was used.
Next, from the rear portion of the polypropylene pipe, a viscoelastic ink backflow prevention member (liquid plug) containing polybutene as a main component is filled, and a tail plug is fitted to the rear portion of the pipe to form a 2-[2-hydroxy -3,5-Bis (α, α-dimethylbenzyl) phenyl]-2H-benzotriazole (manufactured by BASF Japan Co., Ltd., trade name: Tinuvin 234, UV absorber) made of polycarbonate resin mixed with 0.5 parts A front barrel and a rear barrel were assembled, and after degassing by centrifugal treatment, a cap was fitted to obtain a ball-point pen.

Comparative example 1
A ball-point pen was obtained in the same manner as in Example 1, except that the polypropylene pipe was not mixed with an ultraviolet absorber.

Comparative example 2
A marking pen was obtained in the same manner as in Example 2, except that the cap made of polypropylene resin was not mixed with an ultraviolet absorber.

Comparative example 3
A marking pen was obtained in the same manner as in Example 3, except that the barrel and inner cap made of polypropylene resin were not mixed with an ultraviolet absorber.

Comparative example 4
A ball-point pen was obtained in the same manner as in Example 4, except that the polypropylene pipe was not mixed with an ultraviolet absorber and a light stabilizer.

Comparative example 5
A ball-point pen was obtained in the same manner as in Example 7, except that the polycarbonate resin front barrel and rear barrel were not mixed with an ultraviolet absorber.

Lightfastness Test The ballpoint pens and marking pens of Examples 1 to 7 and Comparative Examples 1 to 5 were used to perform the following lightfastness test.
Each ball-point pen and marking pen was irradiated with light for 100 hours using a fade meter (Suga Test Instruments, long-life carbon arc application).
Handwritings made of thermochromic ink and photochromic ink were comprehensively evaluated both before and after discoloration.
The table below shows the lightfastness test results.

In addition, the evaluation regarding the symbol of the test result in a table|surface is as follows.
(double-circle): The handwriting which does not change at all compared with the initial stage was obtained.
◯: Slight fading was observed compared to the initial stage, but practically acceptable handwriting was obtained.
Δ: Browning is observed compared to the initial stage, and with discoloring ink, handwriting due to browning is visible even in a decolored state.
x: Significant color fastness and browning are observed compared to the initial stage, and with discoloring ink, handwriting due to browning is visible even in a decolored state.

REFERENCE SIGNS LIST 1 writing implement 2 cap 21 annular seal portion 22 rear shaft fitting portion 3 pen tip 31 writing portion 32 top portion 33 front portion 34 central portion 35 rear portion 4 holding body 41 holding portion 42 first contact wall portion 43a first rib 43b Second rib 44 Front edge 5 Front shaft 51 Fitting portion 52 Small diameter base 53 Outward engaging portion 53a First outward engaging portion 53b Second outward engaging portion 531 Annular projection 532 Pressure contact surface 54 Slit 55 Stepped portion 56a Second contact wall portion 56b Third contact wall portion 57 Vertical rib 58 Holder fitting portion 59 Holding rib 6 Rear shaft 61 Fitted portion 62 Large diameter base portion 63 Inward locking portion 63a First inward facing portion Engagement portion 63b Second inward engagement portion 631 Annular groove 632 Press contact surface 633 Annular projection 64 Airtight portion 65 Cap fitting portion 7 Ink occluding body 8 Axle tube 9 Friction body t ₁ Heat erasable microcapsule pigment and color memory Complete color development temperature of retention type microcapsule pigment t ₂ Color development start temperature of heat decoloration type microcapsule pigment and color memory retention type microcapsule pigment t ₃ Color decoloration of heat decoloration type microcapsule pigment and color memory retention type microcapsule pigment Start temperature t ₄ Completely decoloring temperature of heat decoloring type microcapsule pigment and color memory retaining type microcapsule pigment T ₁ Completely decoloring temperature of heat color forming type microcapsule pigment T ₂ Color decoloring start temperature of heat color forming type microcapsule pigment T ₃ Color development start temperature of heat color-developing microcapsule pigment T ₄ Complete color development temperature of heat color development microcapsule pigment

Claims (5)

(a) an electron-donating organic compound, (b) an electron-accepting compound, (c) a reversible thermochromic material consisting of a reaction medium that determines the temperature at which the color reaction of the components (a) and (b) occurs, a photochromic organic ink containing a coloring agent selected from materials, dyes, and fluorescent pigments; an ink occluding body containing the ink; a barrel containing the ink occluding body; a pen tip capable of ejecting the ink; A writing instrument comprising a holder for holding a pen tip, and a cap detachably attached to the pen tip side of the barrel and formed of a material having transparency, wherein the cap is coated with an ultraviolet absorber or A writing instrument containing a transparent ultraviolet shielding agent, or having a light stable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent on the surface of the cap. 2. The writing instrument according to claim 1, wherein the cap contains a light stabilizer or the light stable layer contains a light stabilizer. 3. The writing instrument according to claim 1, wherein said holder is made of a transparent material. 4. The writing instrument according to claim 3, wherein the holder contains an ultraviolet absorber or a transparent ultraviolet shielding agent, or a light stable layer containing an ultraviolet absorber or a transparent ultraviolet shielding agent is provided on the surface of the holder. 5. The writing instrument according to claim 4, wherein the holder contains a light stabilizer or the light stable layer contains a light stabilizer.