JP2012166402A - Writing implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a writing implement to which a phase change or an indicator function in consequence of a temperature change can be given when a decoration part such as a decoration body, an inner tube or the like that is visually recognized through an outer tube changes reversibly to visually recognizable and visually unrecognizable states according to the temperature change in the writing implement using a double-tubular barrel, and which is equipped with an interesting and unexpected decorative effect.SOLUTION: The writing implement 1 uses the double-tubular barrel 2 of the inner tube 5 in which a writing implement unit 9 is prepared, and the outer tube 6 which covers the inner tube 5. The outer tube 6 has a reversible thermal discoloring capability and has reversible visual functions of being a transparent state in which the interior is visually recognizable from outside by the temperature change, and being a visually unrecognizable concealment state.

Description

  The present invention relates to a writing instrument. Further, the present invention relates to a writing instrument using a double cylindrical shaft cylinder composed of an inner cylinder and an outer cylinder.

Conventionally, for the purpose of improving the appearance decoration of writing instruments, a double cylinder composed of an inner cylinder and a transparent outer cylinder is used as a shaft cylinder, and a decorative body is provided between the inner cylinder and the outer cylinder. (For example, refer to Patent Documents 1 and 2).
In the writing instrument, the decorative body is housed in the outer cylinder, unlike the outer surface-covered decorative body by transfer or the like, so that the decorative body does not peel off by rubbing or gripping, and the appearance decoration is improved for a long time. It can be maintained.

JP 2004-130625 A Japanese Patent Laid-Open No. 11-309982

According to the present invention, in a writing instrument using a double cylindrical shaft cylinder of this type, a decorative part that is visually recognized through an outer cylinder, such as the decorative body and the inner cylinder, can be visually recognized in accordance with a temperature change. By providing a reversible change in a possible state, it is possible to provide an aspect change and an indicator function accompanying a change in temperature, and to provide a writing instrument that is rich in interest and has an unexpected decorative effect.
In the present invention, “front” indicates the pen tip side, and “rear” indicates the pressing portion side of the knock type writing instrument.

The present invention is a writing instrument using a double cylindrical shaft cylinder of an inner cylinder in which a writing unit is installed and an outer cylinder covering the inner cylinder, the outer cylinder having reversible thermochromic performance. It requires a writing instrument having a reversible visual function in which a transparent state in which the inside can be visually recognized from the outside due to a temperature change and a concealed state that cannot be visually recognized.
Further, a gap is formed between the inner cylinder and the outer cylinder, a decorative body is accommodated in the gap, the decorative body can be taken out from the shaft cylinder, an outer surface or an inner surface of the outer cylinder It is required that a heat decoloring type reversible thermochromic layer is formed on at least one of the above, and that a decorative body is formed on at least one of the outer surface of the inner cylinder and the inner surface of the outer cylinder.
Further, the writing unit is a refill containing a writing material, a writing material cartridge, or a mechanical pencil unit, and the writing material is made of a thermochromic material that changes color when the writing material reaches a certain temperature. In addition, it is a requirement that the indicator part that changes its appearance at a temperature substantially equal to the color change temperature of the thermochromic material is formed on any of the outer cylinder, the inner cylinder, and the decorative body.

According to claim 1, the writing instrument of the present invention is reversible in a state in which a decorative part visually recognized through the outer cylinder, such as a decorative body and an inner cylinder inside the outer cylinder, can be visually recognized according to a change in temperature. As a result of this change, it is possible to impart a change in the appearance and an indicator function accompanying a change in temperature, and it becomes a writing instrument that has an interesting and surprising decorative effect. Therefore, the advertising effect is high and it is useful as a novelty.
Further, since the smoothness of the outer surface of the writing instrument can be maintained as compared with the direct hiding of the decorative body by the coating using the thermochromic film or the coating using the thermochromic ink, it is possible to configure the shaft cylinder having a higher hiding property.

  According to claim 2, since the decorative body formed separately can be accommodated in a writing instrument using a conventional double cylindrical shaft cylinder, a desired writing instrument can be manufactured without newly requiring large equipment such as a mold. . Therefore, it is optimal for novelty applications such as name insertion.

  According to the third aspect, it is possible to replace with a replacement decorative body provided separately, or a decorative body which is freely formed by a user using a printed matter, a sticker, an image of a handwriting, or the like. Therefore, a highly original writing instrument can be made.

  According to the fourth aspect, the thermal discoloration performance can be easily imparted to the transparent resin material constituting the general-purpose writing instrument exterior by painting, printing, or film sticking.

  According to the fifth aspect, since the decorative body can be directly formed on the writing instrument member by printing or sticking, a writing instrument having a high decorative effect can be formed without increasing the number of parts.

  According to the sixth aspect, a general-purpose writing unit can be applied.

  According to the seventh aspect, since the handwriting also changes color with the exterior, the writing tool becomes more surprising.

  According to claim 8, since the discoloration state of the writing material incorporated in the writing instrument can be confirmed by looking at the external indicator part, it is placed in an environment where the temperature is higher or lower than the set discoloration temperature of the writing material during storage. It can be easily judged.

It is an external view which shows an example of embodiment (concealment state) of this invention. It is the external view which shows the outer cylinder transparent state of FIG. 1, and AA 'sectional view taken on the line. It is explanatory drawing which shows the discoloration behavior of a reversible thermochromic material. It is the external view (outer cylinder transparent state) which shows an example of other embodiment of this invention, and a BB 'sectional view taken on the line.

<First embodiment>
A first embodiment of the writing instrument 1 of the present invention will be described with reference to FIGS.
The writing instrument 1 in FIG. 1 is a retractable ballpoint pen in which a pen tip 91 is protruded and retracted from the tip of a shaft cylinder by a pressing operation of a rear end portion. In the writing instrument 1, a ballpoint pen refill in which a thermochromic ink and an ink follower (liquid stopper) are built in an ink storage tube having a nib 91 connected to the tip is used as the writing unit 9, and the ballpoint pen refill is an exterior of the writing instrument. The shaft tube 2 is accommodated inside. In addition, a pressing operation portion 43 is provided at the rear end of the shaft cylinder 2 for allowing the pen tip 91 to protrude from the tip of the shaft cylinder. Further, a clip 42 is provided on the rear outer surface of the shaft tube 2, and the clip 42 functions as a friction body whose curved outer surface in the vicinity of the base 41 discolors the handwriting by the thermochromic ink with frictional heat. It is.

-Shaft cylinder The shaft cylinder 2 which is the writing instrument exterior includes a front shaft 3 having an elastic grip 31 and a base 32 serving as a gripping portion, a rear shaft 4 having a retracting mechanism and a clip 42 attached to a base 41. It is formed by screwing.
The rear shaft 4 is configured by an inner cylinder 5 provided with a base 41 for accommodating a ballpoint pen refill and an outer cylinder 6 having a reversible thermochromic performance that covers the inner cylinder 5 while providing a retracting mechanism. A gap 7 is formed between the inner cylinder 5 and the outer cylinder 6 over the entire outer peripheral surface of the inner cylinder 5.
The outer cylinder 6 is provided by laminating by coating a reversible thermochromic layer 61 on the inner surface of a transparent cylindrical resin molded product whose inner side can be visually recognized. By removing 3, it is configured to be detachable from the front. In addition to the laminated structure in which the reversible thermochromic layer 61 is provided, a resin material obtained by mixing a reversible thermochromic material in a transparent resin material can be molded as the outer cylinder 6.

In the present embodiment, a front shaft 3 (having an elastomeric grip 31 by two-color molding and arranging a spring body therein) obtained by injection molding a resin material obtained by adding a coloring material to polycarbonate resin, The two parts of the rear shaft 4 provided with a pressing operation portion 43 that can move back and forth to operate the retracting mechanism at the rear end are used as the shaft cylinder 2 formed so as to be attachable and detachable in the front and rear direction. The writing instrument exterior is formed by screwing in a state.
The rear shaft 4 is covered so that a gap portion 7 is formed between a colored opaque polycarbonate resin inner cylinder 5 in which a rotating cam mechanism that operates when the pen tip moves in and out and an outer surface of the inner cylinder 5 are formed. Thus, the gap 7 and the inner cylinder 5 are composed of an outer cylinder 6 in which a reversible thermochromic layer 61 is formed on the inner surface of a transparent polycarbonate resin cylinder visible from the outside. Since the outer cylinder 6 is held by the rear end contacting the base 41 and the front end contacting the rear end of the front shaft 3 (the rear end of the grip 31), the front shaft 3 and the rear shaft 4 are retained. It can be easily removed by dividing.

The reversible thermochromic layer 61 is formed by applying a coating ink using a reversible thermochromic material that exhibits a hue and color tone that is concealed in a colored state and is transparent in a decolored state to the inner surface of the transparent cylinder. Is formed.
The reversible thermochromic layer 61 has a concealed state due to a change in appearance in an environmental temperature range (for example, −10 ° C. to 50 ° C., preferably 5 ° C. to 40 ° C.), frictional heat, heating of a dryer, cooling, or the like. The inner decorative body 8 and the inner cylinder 5 are changed depending on the temperature at the place where the writing instrument 1 is used, frictional heat with fingers, heating with a dryer, cooling, etc. Configured to appear. With the above-described configuration, it is possible to form an interesting writing instrument having unprecedented unprecedented ability to visually recognize the internal decorative body as the temperature changes. In particular, when two or more types having different discoloration temperatures are used, a plurality of patterns such as forming a pattern as a configuration in which the inside is partially visually recognized depending on the temperature, or changing to an exterior having a different hue or pattern, etc. It is possible to construct a more decorative item that exhibits the following aspect.

  The reversible thermochromic material applied to the reversible thermochromic layer 61 includes a heat decoloring type that decolorizes by heating from a colored state, and a color that stores and holds the colored state or decolored state in a specific temperature range. Various types such as a memory holding type or a heating coloring type that develops color by heating from the decolored state and returns to the decolored state by cooling from the colored state can be used alone or in combination. The reversible thermochromic material can be used in the form of a microcapsule pigment in which the reversible thermochromic composition is used directly, or the composition is encapsulated in microcapsules.

In the reversible thermochromic material used in the present embodiment, as shown in FIG. 3, the shape of the curve plotting the change of the color density due to the temperature change increases the temperature from the lower temperature side than the color change temperature range. On the contrary, the color changes following a different path from the case where the color change temperature range is lowered from the high temperature side, and the color development state in the low temperature range below the complete color development temperature (t ₁ ), or the complete color erasure temperature (t ₄ ) or higher. Color memory retention type thermochromic material (coating ink form) that can be stored and retained in a specific temperature range [temperature range between t _{2 and} t ₃ (substantially two-phase retention temperature range)] ) Applies. In FIG. 3, ΔH indicates a temperature width (ie, hysteresis width) indicating the degree of hysteresis. When the value of ΔH is small, only one of the two states before and after the color change can exist. When the value of ΔH is large, it is easy to maintain each state before and after the color change. Note that the value of ΔH of the coating ink used for the reversible thermochromic layer 61 is smaller than the value of ΔH of the writing ink, and the complete color erasing temperature (t ₄ ) is also set low.
Further, the reversible thermochromic layer 61 containing the reversible thermochromic material is not only a decoloring type used alone, but also a color changing type to which a non-thermochromic colorant is added within a range in which transparency can be maintained (colored by temperature change). Either a concealed state or a colored transparent state) can be used. In this embodiment, the reversible thermochromic layer that is substantially colorless and transparent at about 30 ° C. is formed using the former decoloring type.

Furthermore, when the ink for writing to accommodate has reversible thermochromic performance, the thermochromic indicator part which changes color at desired temperature using the said reversible thermochromic material can be provided.
The indicator part is formed on a writing instrument exterior visually recognized from the outside, and is formed by painting or sticking on either the outer surface of the outer cylinder 6 or the inner cylinder 5 or the decorative body 8 accommodated in the gap part 7. It is preferable to do.
As the thermochromic material applied to the indicator part, a material set to a temperature substantially equal to or slightly lower than the color changing temperature range of the thermochromic material applied to the ink for writing that changes color by frictional heat is used. It is done. Therefore, for example, the reversible thermochromic layer 61 is provided with an indicator function that indicates a higher temperature state than the temperature along with a change in appearance that occurs in the environmental temperature range. Since the discoloration temperature of the indicator section is set in the vicinity of the discoloration temperature of the writing ink, the state of the ink for writing (the presence or absence of decoloring or discoloration) can be easily determined by checking the appearance, and therefore storage It is possible to immediately check whether the state is suitable.

  The clip 42 is a molded body (specifically, a polyester-based elastomer molded product) that is separately attached to the base 41 of the inner cylinder 5. In the present embodiment in which thermochromic ink is applied, the clip 42 is in the vicinity of the base 41. The outer curved surface portion is used as a friction body. In addition, when the ink incorporated is non-thermochromic, it is possible to attach an integrally molded product or a two-color molded product made of a hard resin material, and a metal workpiece. A binder clip using a spring member such as a spring or elastic resin can also be used.

In order to use the clip 42 in the vicinity of the base 41 as a friction body, the entire clip is formed of a single elastomer. However, the clip 42 is not limited to this configuration. The elastic resin portion may be provided in a shape or a position where at least a part of the outer surface can come into contact with a friction surface such as a paper surface by means such as a combination.
As the material of the elastic resin portion suitable for the friction body, rubber or elastomer having elasticity is preferable, for example, silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butadiene-). Styrene copolymer), fluorine resin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM), and the like. In particular, it is preferably made of a low-abrasion elastic material that does not generate wear debris during friction rather than a high-abrasion elastic material (for example, an eraser).

  The writing instrument exterior using the double cylindrical shaft cylinder 2 is not limited to the configuration of the press-and-retract type writing instrument, but a cap-type writing instrument having a nib at one end or both ends, and a rotary feeding type. It may be other intrusive writing instrument forms such as a slide lever type and a side knock type, a composite writing instrument that accommodates a plurality of writing units, and the like. Further, the constituent material can be appropriately selected and formed from a metal or wood processed body, a synthetic resin molded body or the like.

Decorative Body A decorative body in which a resin sheet on which a printed image 81 on which various designs are printed is formed in the gap portion 7 formed between the inner cylinder 5 and the outer cylinder 6 of the rear shaft 4 is cylindrical. 8 is accommodated so as to be removable. In this embodiment, a printed image is provided with a non-thermochromic ink, but a thermochromic image with a thermochromic ink may be provided so that the decorative body exhibits a change in appearance according to the environmental temperature. . The resin sheet may be adhered to the outer surface of the inner cylinder with an adhesive layer interposed on the back surface.
In addition to the decorative pattern as shown in FIG. 2, the printed image 81 is provided with a name such as a company name or a product name, or a form that can be used as a business card by describing personal information. Higher ones can be used.

Writing unit The writing unit 9 accommodated in the shaft cylinder 2 may be in any form such as replaceable and non-replaceable as long as it is applied to a general-purpose writing instrument, for example, ink or solid Units such as refills and cartridges with built-in writing materials such as drawing materials, mechanical pencil units, direct liquid fountain pens, and marking pen ballpoint pens can be applied.
In the present embodiment, a refill-type writing unit is applied. For example, a pen point 91 is connected directly or through a holder to the tip of an ink containing tube made of a metal thin tube or a cylindrical resin molded body, and the ink The storage tube is filled with thermochromic ink, and an ink follower is disposed at the rear end of the ink if desired. Further, a tail plug having an air passage is provided at the rear end of the refill.

-Pen tip As the pen tip 91, a pen tip for a marking pen such as a fiber tip, a felt tip, a plastic tip, or 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 formed by holding a ball, a chip formed by holding a ball in a ball holding part formed by cutting a metal material with a drill or the like, or a chip formed by cutting a metal pipe or metal material A ballpoint pen tip such as a tip in which a ball to be held is urged forward by a spring body can be applied. In addition, cemented carbide, stainless steel, ruby, ceramic, etc. can be applied to the balls used for the ballpoint pen tip.
In the present embodiment, a ballpoint pen nib 91 is used in which a cemented carbide ball is held in a ball holding portion formed by cutting a metal material, and the ball is biased forward by a spring body.

・ Writing materials (thermochromic ink)
The writing material used for the writing unit 9 is appropriately selected according to the unit 9, such as ink, solid writing material, and mechanical pencil lead. In this embodiment, the coloring material changes color when reaching a certain temperature. A thermochromic water-based ink using a thermochromic material is applied and incorporated in the refill.
The thermochromic ink can use either reversible thermochromic property or irreversible thermochromic type, but it is possible to restore the handwriting erased and discolored by the user to the original handwriting when desired. To reversible thermochromic ink. The reversible thermochromic ink is a heat decoloring type that decolors by heating from a colored state, a color memory retaining type that reversibly stores and retains a colored state or a decolored state in a specific temperature range, or from a decolored state Various types such as a heating coloring type that develops color by heating and returns to a decolored state by cooling from the colored state can be used alone or in combination.

The colorant (thermochromic material) contained in the reversible thermochromic ink is conventionally known (a) electron donating color-forming organic compound, (b) electron accepting compound, and (c). A reversible thermochromic pigment in which a reversible thermochromic composition containing at least the essential three components of the reaction medium for determining the occurrence temperature of the color reaction of both is encapsulated in a microcapsule is preferably used.
Specifically, as shown in FIG. 3, the shape of the curve plotting the change in the color density due to the temperature change is higher than the color change temperature range on the contrary to the case where the temperature is raised from the lower temperature side than the color change temperature range. The color changes by following a different route depending on whether the color is lowered from the color, and the color develops in the low temperature range below the complete color development temperature (t ₁ ) or the color erase state in the high temperature range above the complete color erase temperature (t ₄ ). However, a color memory holding type thermochromic ink (gel ink) that can be stored and held in a specific temperature range [temperature range between t _{2 and} t ₃ (substantially two-phase holding temperature range)] is applied. In FIG. 3, ΔH indicates a temperature width (ie, hysteresis width) indicating the degree of hysteresis. When the value of ΔH is small, only one of the two states before and after the color change can exist. When the value of ΔH is large, it is easy to maintain each state before and after the color change.

In the present embodiment, the color change temperature of the thermochromic ink due to the frictional heat of the friction body is set to 25 ° C. to 95 ° C. (preferably 36 ° C. to 95 ° C.). That is, the high temperature side color change point [complete color erasing temperature (t ₄ )] is set in a range of 25 ° C. to 95 ° C. (preferably 36 ° C. to 90 ° C.), and the low temperature side color change point [complete color development temperature ( It is effective to set (t ₁ )] within a range of −30 ° C. to + 20 ° C. (preferably −30 ° C. to + 10 ° C.). As a result, it is possible to effectively maintain the color exhibited in the normal state (daily life temperature range) and to easily discolor (discolor) the handwriting by the reversible thermochromic ink with frictional heat from the friction body. it can.

<Second Embodiment>
A second embodiment of the writing instrument 1 of the present invention is shown in FIGS. 4 and 1 (decorative body concealment state).
As the writing unit 9, the exterior member (excluding the decorative portion and the reversible thermochromic layer) constituting the writing instrument 1 of FIG. 4 uses a ballpoint refill containing oil-based ink in an ink containing tube connected to the tip of the pen tip 91. Except for this, it is a ballpoint pen of the retractable form having the same structure as the first embodiment. A metal workpiece is used for the clip 42.

-Shaft tube The shaft tube 2 which is the writing instrument exterior is to screw the front shaft 3 having an elastic grip 31 and a base 32 serving as a gripping portion, and the rear shaft 4 having a metal clip 42 attached to the base portion 41. Formed with.
The rear shaft 4 is configured by an inner cylinder 5 provided with a base 41 for accommodating a ballpoint pen refill and an outer cylinder 6 having a reversible thermochromic performance that covers the inner cylinder 5 while providing a retracting mechanism. A gap 7 is formed between the inner cylinder 5 and the outer cylinder 6 over the entire outer peripheral surface of the inner cylinder 5. The outer cylinder 6 is provided with a reversible thermochromic performance by coating a reversible thermochromic layer 61 on the outer surface of a transparent cylindrical resin molded product whose inside can be visually recognized.

In the present embodiment, the front shaft 3 (including the grip 31 and the base 32) obtained by injection molding a resin material obtained by adding a coloring material to polycarbonate resin, and the pressing operation unit 43 are disposed at the rear end. A shaft cylinder 2 is used in which two parts of the rear shaft 4 are detachable in the front-rear direction, and a writing instrument exterior is formed by screwing the two parts in a refill accommodation state.
The rear shaft 4 is covered so that a gap 7 is formed between a colored opaque polycarbonate resin inner cylinder 5 on which an ornamental body 8 is formed by printing or transfer and an outer surface of the inner cylinder 5. Thus, the gap 7 and the decorative body 8 are constituted by an outer cylinder 6 in which a reversible thermochromic layer 61 is formed on the outer surface of a transparent polycarbonate resin cylinder visible from the outside. Since the outer cylinder 6 is held by the rear end contacting the base 41 and the front end contacting the rear end of the front shaft 3 (the rear end of the grip 31), the front shaft 3 and the rear shaft 4 are retained. It can be easily removed by dividing.

The reversible thermochromic layer 61 is formed by coating the outer surface of a transparent cylinder with a coating ink using a reversible thermochromic material that exhibits a hue and color tone that is concealed in a colored state and is transparent in a decolored state. It is formed and a reversible visual function is added to the shaft cylinder.
The reversible thermochromic layer 61 has a concealed state due to a change in appearance in an environmental temperature range (for example, −10 ° C. to 50 ° C., preferably 5 ° C. to 40 ° C.), frictional heat, heating of a dryer, cooling, or the like. The light-transmitting state changes, and the internal decorative body 8 appears by the temperature range of the place where the writing instrument 1 is used, frictional heat with fingers, heating, cooling, etc. The As a result, it is possible to form an interesting writing instrument having unprecedented unprecedented ability to make the internal decorative body 8 visible by temperature change. In particular, when two or more types having different discoloration temperatures are used, a plurality of patterns such as forming a pattern as a configuration in which the inside is partially visually recognized depending on the temperature, or changing to an exterior having a different hue or pattern, etc. It is possible to construct a more decorative item that exhibits the following aspect.

As the reversible thermochromic material applied to the reversible thermochromic layer 61, those described above with reference to FIG. 3 can be applied, and the reversible thermochromic composition can be directly used, and the composition can be used as a microcapsule. It can be used in the form of a microcapsule pigment encapsulated in.
Further, the reversible thermochromic layer 61 containing the reversible thermochromic material is a color-changing type in which a non-thermochromic colorant is added as long as the transparency can be maintained in addition to the decoloring type using the thermochromic material alone. Any of the types (presenting a colored concealed state and a colored transparent state by temperature change) can be used. In this embodiment, the reversible thermochromic layer that is substantially colorless and transparent at about 35 ° C. is formed using the former decoloring type.

Furthermore, a light-transmitting bright layer or topcoat layer can be formed on the upper surface of the reversible thermochromic layer 61, and a decorative effect can be imparted, light resistance and strength can be improved.
In this embodiment, after forming the reversible thermochromic layer 61 on the entire outer surface using the transparent outer cylinder 6 as a support, coating ink containing a light-transmitting glittering material (specifically, a helicone) is applied to the entire surface. A light-transmitting bright layer is formed by coating, and a top coat layer containing an ultraviolet absorber is further laminated. In addition, by forming a light-transmitting bright layer on the upper surface of the reversible thermochromic layer 61, the decorative effect and light resistance are improved, and the concealability when coloring the reversible thermochromic layer 61 is higher.

-Decorative body Decorative body 8 (on the outer surface of the inner cylinder 5 where the gap 7 is formed by direct printing such as transfer or sticking of a film on which a pattern or characters are printed, pad printing, silk printing, inkjet printing, etc.) A printed image 81) is formed.
In this embodiment, personal information including a company name, a department name, and a name is provided as a printed image 81 by silk printing using non-thermochromic ink, and can be used as a business card. Therefore, a visual effect that personal information appears due to a temperature change can be expressed, so that the unexpectedness and topicality are high and the novelty effect is high. In addition, a thermochromic image using thermochromic ink may be provided as the printed image 81, and the decorative body may change its appearance according to the environmental temperature.

-Writing unit The writing unit 9 accommodated in the shaft cylinder 2 may be of any form such as a replaceable type and a non-replaceable type as long as it is applied to a general-purpose writing instrument. A writing unit in the form of a ballpoint pen refill is applied. Specifically, a pen point 91 is connected to the tip of an ink containing tube made of polypropylene pipe via a holder, and the ink containing tube is filled with oil-based ink, and an ink follower (liquid stopper) is placed at the rear end of the ink. ) Is arranged. Further, a replaceable ballpoint pen refill is configured by providing a tail plug having an air passage at the rear end of the ink containing tube.

DESCRIPTION OF SYMBOLS 1 Writing instrument 2 Shaft cylinder 3 Front shaft 31 Grip 32 Base 4 Rear shaft 41 Base 42 Clip 43 Pressing operation part 5 Inner cylinder 51 Support part 6 Outer cylinder 61 Reversible thermochromic layer 7 Gap part 8 Decoration body 81 Thermochromic image 82 Non-thermal Discolored image 9 Writing unit 91 Pen tip t ₁ Complete color development temperature t ₂ Color development start temperature t ₃ Color erase start temperature t ₄ Complete color erase temperature ΔH Hysteresis width

Claims (8)

A writing instrument using a double cylindrical shaft cylinder of an inner cylinder in which a writing unit is installed and an outer cylinder covering the inner cylinder,
A writing instrument having a reversible visual function in which the outer cylinder has a reversible thermochromic performance and has a transparent state in which the inside can be visually recognized from the outside and a concealed state invisible due to a temperature change.   The writing instrument according to claim 1, wherein a gap is formed between the inner cylinder and the outer cylinder, and a decorative body is accommodated in the gap.   The writing instrument according to claim 2, wherein the decorative body is removable from the shaft tube.   The writing instrument according to any one of claims 1 to 3, wherein a heat decoloring type reversible thermochromic layer is formed on at least one of an outer surface and an inner surface of the outer cylinder.   The writing instrument according to claim 1, wherein a decorative body is provided on at least one of the outer surface of the inner cylinder and the inner surface of the outer cylinder.   The writing instrument according to any one of claims 1 to 5, wherein the writing unit is one of a refill containing a writing material, a writing material cartridge, and a mechanical pencil unit.   The writing instrument according to claim 6, wherein the writing material is a thermochromic material that changes color when reaching a certain temperature as a colorant.   The writing instrument according to claim 7, wherein the indicator portion that changes in appearance at a temperature substantially equal to the color change temperature of the thermochromic material is formed on any of an outer cylinder, an inner cylinder, and a decorative body.

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