JP2009090559A - Thermo-discolorable ball-point pen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermo-discolorable ball-point pen in which fluidity of thermo-discolorable ink in a ball-point pen chip at the rear of a ball receiving seat is improved, and occurrence of breaking of handwriting and a reduction in density of handwriting are prevented. <P>SOLUTION: The thermo-discolorable ball-point pen is composed of: a ball-point pen chip 2 rotatably holding a ball 31 at the front edge; and an ink storage part 6 provided with the ball-point pen chip 2 at the front edge and whose rear edge is opened. In the inside of the ink storage part 6, thermo-discolorable ink 8 and a following body 9 are stored. The ball-point pen chip 2 is composed of: a right cylindrical small-diameter part 3; a right cylindrical large-diameter part 4; and a taper part 5 connecting the small-diameter part 3 to the large-diameter part 4. A spring 7 energizing the ball 31 to the front is arranged at the rear of the ball 31. The ratio of the inside diameter B at the rear of the ball receiving seat 33 in the small-diameter part 3 to the ball outside diameter A is 1.01 to 1.15. The ratio of the inside diameter C of the large-diameter part 4 to the ball outside diameter A is 1.2 to 3.0. The length L in an axial direction from the ball receiving seat 33 to the rear edge of the small-diameter part 3 is ≤3 mm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a thermochromic ballpoint pen incorporating a thermochromic ink.

Conventionally, Patent Document 1 describes a thermochromic ballpoint pen using a pipe-pressing-deformation type ballpoint pen tip in which the vicinity of the tip of a metal pipe is pressed and deformed inward.
However, when the conventional thermochromic ballpoint pen has a small ball outer diameter (specifically, a ball outer diameter of 0.5 mm or less), the fluidity of the thermochromic ink in the ballpoint tip behind the ball seat is low. As a result, the handwriting may be interrupted or the concentration of the handwriting may be insufficient.

Japanese Patent No. 3718752

The present invention solves the above-described conventional problems, improves the fluidity of the thermochromic ink in the ballpoint pen tip behind the ball seat, and can prevent the occurrence of breaks in handwriting and a decrease in handwriting density. An object is to provide a thermochromic ballpoint pen.

1st invention of this application consists of the ball-point pen tip 2 which held the ball | bowl 31 rotatably at the front end, and the ink accommodating part 6 which was equipped with the said ball-point pen tip 2 in the front end, and the back end opened, The said ink accommodating part 6 includes a thermochromic ink 8 and a follower 9 which is disposed at the rear end of the thermochromic ink 8 and advances as the thermochromic ink 8 is consumed. The thermochromic ink 8 is a ballpoint pen, wherein a thermochromic pigment having an average particle size of 0.5 μm to 5 μm is dispersed in an aqueous medium and has a viscosity of 40 mPa · s to 160 mPa · s (according to an EM type rotational viscometer). The rotation point of 100 rpm, the value at 25 ° C.), the high temperature side discoloration point is set to 25 ° C. to 95 ° C., and the ballpoint pen tip 2 includes a right cylindrical cylindrical small diameter portion 3 and a straight cylindrical large diameter portion. 4, the small diameter portion 3 and the large diameter portion And a ball receiving seat 33 comprising an inwardly facing front end edge 32 and an inward projection 33a formed by inward pressing deformation. And a spring 7 for urging the ball 31 forward is disposed behind the ball 31. The spring 7 penetrates the ink passage 33b of the ball receiving seat 33 and the front end contacts the rear surface of the ball 31. And a coil portion 72 integrally connected to the rear end of the rod portion 71. The outer diameter A of the ball 31 is 0.3 mm to 0.7 mm. The movable amount in the direction is 10 μm to 60 μm, the movable amount in the radial direction of the ball 31 is 10 μm to 60 μm, and the inner diameter B of the small diameter portion 3 behind the ball receiving seat 33 is relative to the ball outer diameter A. Ratio (B / A) is 1.01-1.15, and the ratio (C / A) of the inner diameter C of the large diameter portion 4 to the ball outer diameter A is 1.2-3.0, and the ball receiver The length L in the axial direction from the seat 33 to the rear end of the small diameter portion 3 is 3 mm or less (claim 1).

In the thermochromic ballpoint pen 1 of the first invention, the fluidity of the thermochromic ink 8 does not deteriorate in the ballpoint pen tip 2 behind the ball receiving seat 33, and a sufficient amount of the thermochromic ink 8 is applied to the ball. As a result, there is no possibility that the handwriting is interrupted or the density of the handwriting is reduced.

In the thermochromic ballpoint pen 1 of the first invention, since the rod portion 71 passes through the ink passage 33b of the ball receiving seat 33 and the front end of the rod portion 71 contacts the rear surface of the ball 31, the front end portion of the spring 7 is The ink passage 33b of the penetrating ball receiving seat 33 can be set as large as possible, and the fluidity of the thermochromic ink 8 in the ink passage 33b of the ball receiving seat 33 can be improved. If the coil portion having a small diameter penetrates the ink flow path of the ball receiving seat 33, the ink fluidity in the ink passage 33b of the ball receiving seat 33 is lowered, and the thermochromic ink 8 from the nib is sufficiently removed. Discharge cannot be obtained. The ball 31 is brought into intimate contact with the inward front edge 32 by the forward bias of the spring 7 to prevent ink leakage and air mixing from the pen tip when not in use.

When the ball 31 has a movable amount in the axial direction of 10 μm to 60 μm, sufficient ink outflow from the pen tip and stable writing feeling can be obtained. If the amount of movement of the ball 31 in the axial direction is less than 10 μm, sufficient ink outflow from the pen tip cannot be obtained. If the amount of movement of the ball 31 in the axial direction is larger than 60 μm, the ball 31 is largely shaken in the axial direction during writing, and a stable writing feeling cannot be obtained.

When the ball 31 has a movable amount in the radial direction of 10 μm to 60 μm, sufficient ink outflow from the pen tip and stable writing feeling can be obtained. If the amount of movement of the ball 31 in the radial direction is less than 10 μm, sufficient ink outflow from the pen tip cannot be obtained. If the amount of movement of the ball 31 in the radial direction is larger than 60 μm, the ball 31 is greatly rattled in the radial direction during writing, and a stable writing feeling cannot be obtained.

When the ratio (B / A) of the inner diameter B of the small diameter portion 3 behind the ball receiving seat 33 to the outer diameter A of the ball is 1.01-1.15, sufficient thermochromic ink in the small diameter portion 3 is obtained. The fluidity of 8 is obtained, and the ballpoint pen tip 2 can be easily manufactured. If the ratio (B / A) is smaller than 1.0, sufficient ink fluidity in the small diameter portion 3 cannot be obtained. If the ratio (B / A) is greater than 1.15, the inner diameter of the front of the ball receiving seat 33 and the inner diameter of the rear of the ball receiving seat 33 are greatly different, making it difficult to manufacture the ballpoint pen tip 2.

When the ratio (C / A) of the inner diameter C of the large diameter portion 4 to the ball outer diameter A is 1.2 to 3.0, sufficient fluidity of the thermochromic ink 8 in the large diameter portion 4. The ballpoint pen tip 2 can be easily manufactured. When the ratio (C / A) is smaller than 1.2, the ink fluidity in the large diameter portion 4 is lowered. When the ratio (C / A) is larger than 3.0, the outer diameter difference between the large diameter portion 4 and the small diameter portion 3 increases as the inner diameter difference between the large diameter portion 4 and the small diameter portion 3 increases. The appearance of the ballpoint pen tip 2 is hindered.

When the length L in the axial direction from the ball receiving seat 33 of the small diameter portion 3 to the rear end of the small diameter portion 3 (the rear end of the taper portion 5) is 3 mm or less, sufficient thermochromic ink in the small diameter portion 3 is obtained. A fluidity of 8 is obtained. If the length L in the axial direction is larger than 3 mm, the fluidity of the thermochromic ink 8 in the small diameter portion 3 is lowered.

The second aspect of the present invention is the first invention, the minimum cross-sectional area of the ink passage 33b of the ball seat 33 is 0.003 mm ² or more (preferably, 0.01 mm ² or more) is (claim 1 ) As a requirement. In the present invention, the minimum cross-sectional area of the ink passage 33b of the ball receiving seat 33 refers to a cross-sectional area of a portion excluding the rod portion 71 of the spring 7. (See Figure 2)

The thermochromic ballpoint pen 1 of the second invention obtains sufficient fluidity of the thermochromic ink 8 in the ink passage 33 b of the ball receiving seat 33.

According to a third invention of the present application, in the second invention, the rod portion 71 is disposed in the small diameter portion 3, the taper portion 5 and the large diameter portion 4 behind the ball 31, and the rear end of the rod portion 71. And the coil portion 72 is disposed in the ink containing portion 6 behind the ball-point pen tip 2 (claim 3).

In the thermochromic ballpoint pen 1 of the third invention, the coil portion 72 does not hinder the fluidity of the thermochromic ink 8 in the ballpoint pen tip 2 and can ensure a large ink flow path in the ballpoint pen tip 2, Since the rod portion 71 has an ink guiding function in the ballpoint pen tip 2, the fluidity of the thermochromic ink 8 in the ballpoint tip 2 is significantly improved. If the coil portion 72 is disposed in the ballpoint pen tip 2, a sufficient ink flow path in the ballpoint pen tip 2 cannot be ensured, and the thermochromic ink 8 does not flow smoothly in the ballpoint pen tip 2, but from the pen tip. There is a possibility that the ink outflow property of the ink may be reduced.

According to a fourth invention of the present application, in the third invention, the large diameter portion 4 is press-fitted and fixed to the inner surface of the front end portion of the ink containing portion 6, and the large diameter portion is press-fitted and fixed to the inner surface of the front end portion of the ink containing portion 6. It is a requirement that a step portion 61a with which the rear end of 4 is in contact is formed, and that the inner diameter D of the step portion 61a is set to be substantially equal to the inner diameter C of the rear end of the large diameter portion 4 (Claim 3).

In the thermochromic ballpoint pen 1 of the fourth invention, the ink flowability does not decrease in the step portion 61a, and smoother ink fluidity is obtained, and the step portion 61a and the rear end of the large diameter portion 4 Get proper contact. If the inner diameter D of the stepped portion 61a is smaller than the inner diameter C of the rear end of the large diameter portion 4, the ink fluidity from the ink containing portion 6 to the large diameter portion 4 is lowered. If the inner diameter D of the stepped portion 61a is larger than the inner diameter C of the rear end of the large diameter portion 4, proper contact between the stepped portion 61a and the rear end of the large diameter portion 4 cannot be obtained. Further, when the inner diameter D of the stepped portion 61a is larger than the inner diameter C of the rear end of the large diameter portion 4, when the rod portion 71 is inserted into the ballpoint pen tip 2, the rear end of the ball pen tip 2 (the rear end of the large diameter portion 4). There is a possibility that the rod portion 71 may be caught on the end) and hinder smooth insertion and assembly.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the number of inward protrusions 33a constituting the ball receiving seat 33 is four (claim 5).

The thermochromic ballpoint pen 1 according to the fifth aspect of the invention can form an ink passage 33b having sufficient ink fluidity in the ball receiving seat 33 and properly guides the front end of the rod portion 71 to the center of the rear surface of the ball 31. Can do. As a result, an appropriate sealing property between the ball 31 and the front end edge portion 32 is obtained. If the number of the inward protrusions 33a constituting the ball receiving seat 33 is three, it may be difficult to properly guide the front end of the rod portion 71 to the center of the rear surface of the ball 31.

According to a sixth invention of the present application, in any one of the first to fifth inventions, the friction body 102 that can rub the handwriting of the thermochromic ink 8 and thermally change the handwriting with frictional heat generated at that time. It is a requirement that it is provided on the outer surface (claim 6).

The thermochromic ballpoint pen 1 according to the sixth aspect of the present invention can easily discolor the handwriting of the thermochromic ink 8 properly obtained from the front end of the ballpoint pen tip 2 by friction without using a large heating means. it can.

-Thermochromic ink In the present invention, the thermochromic ink is preferably a 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 coloring material contained in the reversible thermochromic ink includes conventionally known (a) electron donating color-forming organic compounds, (b) electron-accepting compounds, and (c) color reactions of both. A reversible thermochromic pigment in which a reversible thermochromic composition containing at least the essential three components of a reaction medium for determining the occurrence temperature of the polymer is encapsulated in a microcapsule is preferably used.

In the present invention, as shown in FIG. 8, the shape of the curve plotting the change in color density due to the temperature change is opposite to the case where the temperature is raised from the lower temperature side than the color change temperature range, and from the higher temperature side than the color change temperature range. The color changes by following a different path depending on the descending state, and the color development state 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 ) It is preferable to apply a color memory retention type thermochromic ink 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)]. In FIG. 8, ΔH represents 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 invention, the color change temperature due to frictional heat of the friction body of the thermochromic ink is set to 25 ° C. to 95 ° C. (preferably 36 ° C. to 95 ° C.). That is, in the present invention, the high temperature side discoloration point [complete decoloring 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 discoloration point [ It is effective to set the complete color development temperature (t ₁ )] in the range of −30 ° C. to + 20 ° C. (preferably −30 ° C. to + 10 ° C.). Thereby, it is possible to effectively maintain the color exhibited in the normal state (daily life temperature range), and it is possible to easily change the handwriting by the reversible thermochromic ink with the frictional heat generated by the friction body.

The reversible thermochromic pigment preferably has an average particle diameter in the range of 0.5 to 5.0 μm, preferably 1 to 4 μm. When the average particle diameter exceeds 5.0 μm, the outflow from the capillary gap of the ballpoint pen tip or the porous pen body decreases, and when the average particle diameter is 0.5 μm or less, it is difficult to show high density color development. .

The reversible thermochromic 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 composition. If it is less than 2% by weight, the color density is insufficient, and if it exceeds 50% by weight, the ink outflow is reduced and the writing property is impaired.

-Friction body In the present invention, the friction body is preferably formed of a synthetic resin (rubber or elastomer) having elasticity. The elastic synthetic resin (rubber, elastomer) is, for example, silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butadiene-styrene copolymer), fluorine-based resin, Examples include chloroprene resin, nitrile resin, polyester resin, and ethylene propylene diene rubber (EPDM). It is preferable that the synthetic resin having elasticity constituting the friction body is made of a low-abrasion elastic material that does not generate a debris during friction rather than a high-abrasion elastic material (for example, an eraser). In the present invention, the friction body is provided on the outer surface of the shaft tube or the outer surface of the cap of the thermochromic writing instrument. Examples of the means for attaching the friction body to the shaft cylinder and the means for attaching the friction body to the cap include means such as press-fitting, fitting, engaging, screwing, adhesion, or integral molding by two-color molding. .

The thermochromic ballpoint pen of the present invention improves the fluidity of the thermochromic ink in the ballpoint pen tip behind the ball seat, and can prevent the handwriting from being interrupted and the handwriting density from being lowered.

<First Embodiment>
A first embodiment of the present invention will be described with reference to the drawings. (See FIGS. 1 to 3)
The thermochromic ballpoint pen 1 of the present embodiment includes a ballpoint pen tip 2 that holds a ball 31 rotatably at the front end, and an ink storage portion 6 that includes the ballpoint pen tip 2 at the front end and has an open rear end. Housed in the ink containing portion 6 is a thermochromic ink 8 and a follower 9 that is disposed in contact with the rear end of the thermochromic ink 8 and moves forward as the thermochromic ink 8 is consumed. Is done. The ink storage unit 6 includes a pen tip holder 61 and an ink storage cylinder 62. The rear end portion of the ballpoint pen tip 2 is press-fitted and fixed to the front end portion of the pen tip holder 61, and the rear end portion of the pen tip holder 61 is press-fitted and fixed to the front end portion of the ink containing cylinder 62. A spring 7 that urges the ball 31 forward is disposed behind the ball 31.

Ballpoint pen tip The ballpoint pen is integrally connected to the small cylindrical portion 3 having a constant outer diameter and a constant inner diameter, and the rear end of the small diameter portion 3, and the outer diameter gradually increases rearward. It comprises a tapered portion 5 and a straight cylindrical large-diameter portion 4 having a constant outer diameter and a constant inner diameter, which are integrally connected to the rear end of the tapered portion 5. The ballpoint pen is made of metal (for example, austenitic stainless steel such as SUS304, SUS321, and SUS316).

Small-diameter portion A ball 31 is rotatably held at the front end of the small-diameter portion 3. An inward front edge portion 32 is formed at the front end of the small diameter portion 3 by caulking deformation. A plurality of (specifically, four) inward projections 33 a are formed on the rear side wall of the front end edge portion 32 of the small-diameter portion 3 by inward pressing deformation, and constitute a ball receiving seat 33. A ball 31 is rotatably held between the front end edge portion 32 and the ball receiving seat 33.

An ink passage 33 b is formed between the inward projections 33 a of the ball receiving seat 33. The minimum cross-sectional area of the ink passage 33b of the ball receiving seat 33 is set to 0.01 mm ² or more. (See Figure 2)

The outer diameter A of the ball 31 is in the range of 0.3 mm to 0.7 mm. The axially movable amount of the ball 31 is set in the range of 10 μm to 60 μm. The movable amount of the ball 31 in the radial direction is set in a range of 10 μm to 60 μm. The ratio (B / A) of the inner diameter B of the small diameter portion 3 behind the ball receiving seat 33 to the ball outer diameter A is set to 1.01 to 1.15. The axial length L from the ball receiving seat 33 of the small diameter portion 3 to the rear end of the small diameter portion 3 is set to 3 mm or less (preferably 1 mm to 3 mm).

Tapered portion The tapered portion 5 smoothly connects the rear end of the small diameter portion 3 and the front end of the large diameter portion 4. In the present embodiment, the tapered portion 5 is formed in a conical surface shape, and the angle formed with the axis of the inclined surface of the tapered portion 5 is set to 5 degrees to 25 degrees. In the present invention, the taper portion 5 may have any shape that increases in diameter as the inner diameter and the outer diameter move rearward, and may have a curved surface shape (for example, a convex curved surface shape or a concave curved surface shape) in addition to a conical surface shape. Good.

Large-diameter portion The large-diameter portion 4 has an inner diameter larger than the inner diameter of the small-diameter portion 3 and an outer diameter larger than the outer diameter of the small-diameter portion 3, and has an inner diameter and a taper equal to the inner diameter of the rear end of the tapered portion 5. The outer diameter of the part 5 is equal to the outer diameter of the rear end. The ratio (C / A) of the inner diameter C (the inner diameter C of the large diameter portion 4) of the rear end of the large diameter portion 4 to the ball outer diameter A is set to 1.2 to 3.0. The rear end of the large-diameter portion 4 is in contact with an annular step portion 61 a formed on the inner surface of the front end portion of the pen tip holder 61. The inner diameter C of the rear end of the large diameter portion 4 is set to be substantially the same as the inner diameter D of the stepped portion 61a.

The spring 7 includes a rod portion 71 that passes through the ink passage 33 b of the ball receiving seat 33 and whose front end contacts the rear surface of the ball 31, and a coil portion that is integrally connected to the rear end of the rod portion 71. 72. The rod portion 71 is disposed in the ball-point pen tip 2 (that is, in the small-diameter portion 3, the taper portion 5, and the large-diameter portion 4), and the rear end of the rod portion 71 and the coil portion 72 are located behind the ball-point pen tip 2. The ink storage section 6 is disposed. At the rear end of the coil portion 72, a tightly wound portion 72a whose diameter increases toward the rear is formed. The rear end of the tightly wound portion 72 a is locked to a locking portion 61 b formed on the inner surface of the pen tip holder 61.

Ink storage unit The ink storage unit 6 includes a pen tip holder 61 and an ink storage cylinder 62. Both ends of the ink containing cylinder 62 are opened. The rear end portion of the pen tip holder 61 is press-fitted and fixed to the front end opening of the ink storage tube 62, and the tail plug 63 is press-fitted and fixed to the rear end opening of the ink storage tube 62. The tail plug 63 is provided with a vent hole in the axial direction.

Thermochromic ink In the ink container 6, a thermochromic ink 8 and a high-viscosity fluid that is placed in contact with the rear end of the thermochromic ink 8 and moves forward as the thermochromic ink 8 is consumed. A follower 9 consisting of the above is accommodated. In the thermochromic ink 8, a thermochromic pigment having an average particle size of 0.5 μm to 5 μm is dispersed in an aqueous medium, and the viscosity is 40 mPa · s to 160 mPa · s (rotation speed 100 rpm, 25 ° C. by EM type rotational viscometer). Value). The thermochromic ink 8 has a high temperature side color change point (complete color erasing temperature) set to 36 ° C. to 90 ° C., and a low temperature side color change point (complete color development temperature) set to a range of −30 ° C. to + 10 ° C. . The follower 9 includes a configuration using only a high-viscosity fluid, a configuration using a high-viscosity fluid and a solid together, a movable stopper made of an elastic material, and the like.

<Second Embodiment>
A second embodiment of the present invention will be described with reference to the drawings. (See FIGS. 1 to 4)
In the thermochromic ballpoint pen 1 of the present embodiment, the ballpoint pen refill of the first embodiment is accommodated in the shaft cylinder 10, and a pen tip (ballpoint pen tip 2) is provided outside the front end hole 101 of the shaft cylinder 10. Is a protruding one.

A cap 11 is detachably provided on the pen tip side of the shaft tube 10. A pen nib seal member 111 made of an elastic material that seals the front end of the nib is accommodated in the cap 11.

A friction body 102 made of an elastic material is attached to the rear end portion of the shaft tube 10. The friction body 102 rubs the handwriting of the thermochromic ink 8 and the handwriting of the thermochromic ink 8 can be discolored by frictional heat during friction.

The shaft cylinder 10 includes a front shaft 10a and a rear shaft 10b. The rear end portion of the front shaft 10a and the rear end portion of the rear shaft 10b are detachably attached by screwing. A front end hole 101 is opened at the front end of the front shaft 10a. A friction body 102 is press-fitted and fixed to the rear end of the rear shaft 10b.

<Third Embodiment>
A third embodiment of the present invention will be described with reference to the drawings. (See FIGS. 1, 2, 3, and 5)
The thermochromic ballpoint pen 1 of the present embodiment accommodates the ballpoint refill of the first embodiment in the axial tube 10 so as to be movable in the axial direction, and the pen tip (from the front end hole 101 of the axial tube 10 ( The ball-point pen tip 2) is configured to be able to appear and retract. A friction body 102 made of an elastic material is fixed to the outer peripheral edge portion of the front end portion of the shaft tube 10.

An in / out mechanism is provided in the shaft tube 10, and the pen tip is in / out by an external operation. In the present embodiment, the retracting mechanism is a rear end knock type that presses the rear end portion of the shaft tube 10, but other than this, a rotary type, a side knock type, or the like can be given.

<Fourth embodiment>
A fourth embodiment of the present invention will be described with reference to the drawings. (See FIGS. 1, 2, 6, and 7)
The thermochromic ballpoint pen 1 of the present embodiment accommodates a plurality of ballpoint pen refills in an axial tube 10 so as to be movable in the axial direction, and a pen tip (ballpoint pen tip 2) is inserted from the front end hole 101 of the axial tube 10. As an alternative, it is designed to appear and disappear. A friction body 102 made of an elastic material is fixed to the rear end portion of the shaft tube 10.

Ball pen refill The ball pen refill is composed of a ball pen tip 2 that has a ball 31 rotatably held at its front end, and an ink container 6 that has the ball pen tip 2 at its front end and has an open rear end. Housed in the ink containing portion 6 is a thermochromic ink 8 and a follower 9 that is disposed in contact with the rear end of the thermochromic ink 8 and moves forward as the thermochromic ink 8 is consumed. Is done.

The ink storage unit 6 includes a pen tip holder 61 and an ink storage cylinder 62. The rear end portion of the ballpoint pen tip 2 is press-fitted and fixed to the front end portion of the pen tip holder 61, and the rear end portion of the pen tip holder 61 is press-fitted and fixed to the front end portion of the ink containing cylinder 62. A spring 7 that urges the ball 31 forward is disposed behind the ball 31.

An operation body 64 is attached to the rear end opening of each of the ink storage cylinders 62 by press fitting. The operating body 64 does not completely block the rear end opening of the ink containing cylinder 62, and allows the inside and outside air of each ink containing cylinder 62 to be vented.

A plurality of window holes 103 extending in the axial direction are formed in the side wall of the shaft cylinder 10, and the operating body 64 protrudes from the window holes 103 to the outside. By sliding the one operating body 64 forward along the window hole 103, the pen tip of the ballpoint pen refill corresponding to the operating body 64 is projected outside from the front end hole 101 of the shaft tube 10, and the tip The pen tip of the ballpoint pen refill that was in the protruding state is immersed in the shaft tube 10. The operation body 64 is colored in the color of the colored state of the thermochromic ink 8 inside the ink containing cylinder 62 to which the operation body 64 is attached.

In the present embodiment, the ball-point pen tip 2, the pen tip holder 61, the spring 7, the thermochromic ink 8, and the follower 9 are the same as those in the first embodiment, so that the description is omitted. Omitted.

It is a principal part expanded longitudinal cross-sectional view of embodiment of this invention. FIG. 2 is an enlarged end view taken along line XX in FIG. 1. It is a longitudinal cross-sectional view which shows the 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the 4th Embodiment of this invention. It is a longitudinal cross-sectional view which shows the ball-point pen refill and operation body of FIG. It is explanatory drawing which shows the color change behavior of a thermochromic ink.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermochromic ball-point pen 2 Ball-point pen tip 3 Small diameter part 31 Ball 32 Front edge part 33 Ball receiving seat 33a Inner protrusion 33b Ink passage 4 Large diameter part 5 Taper part 6 Ink accommodating part 61 Pen tip holder 61a Step part 61b Locking part 62 Ink storage cylinder 63 Tail plug 64 Operation body 7 Spring 71 Rod section 72 Coil section 72a Close-contact winding section 8 Thermochromic ink 9 Follow-up body 10 Shaft cylinder 101 Front end hole 102 Friction body 103 Window hole 10a Front shaft 10b Rear shaft 11 Cap 111 Pen point seal member A Ball outer diameter B Inner diameter C behind the small diameter ball bearing seat Large inner diameter D at the rear end of the large diameter portion Step inner diameter L Length from the ball receiving seat to the rear end of the small diameter portion

Claims (6)

A ballpoint pen tip that rotatably holds a ball at the front end, and an ink storage portion that includes the ballpoint pen tip at the front end and that has an open rear end. Inside the ink storage portion, the thermochromic ink and the heat A thermochromic ballpoint pen that is disposed at the rear end of the color-changing ink and accommodates a follower that moves forward with consumption of the thermochromic ink,
In the thermochromic ink, a thermochromic pigment having an average particle diameter of 0.5 μm to 5 μm is dispersed in an aqueous medium, and the viscosity is 40 mPa · s to 160 mPa · s (rotation speed 100 rpm, 25 ° C. by EM type rotational viscometer). Value), the high temperature side discoloration point is set to 25 ° C to 95 ° C,
The ballpoint pen tip consists of a straight cylindrical small diameter portion, a straight cylindrical large diameter portion, and a tapered portion connecting the small diameter portion and the large diameter portion,
On the front end portion of the small diameter portion, an inward front end edge portion and a ball receiving seat made of an inward protrusion formed by inward pressing deformation,
A spring for urging the ball forward is disposed behind the ball, and the spring penetrates the ink passage of the ball receiving seat and the front end contacts the rear surface of the ball, and the rear of the rod portion. It consists of a coil part integrally connected to the end,
The outer diameter A of the ball is 0.3 mm to 0.7 mm,
The axially movable amount of the ball is 10 μm to 60 μm,
The ball can move in the radial direction from 10 μm to 60 μm,
The ratio (B / A) of the inner diameter B of the small diameter portion at the rear of the ball seat to the outer diameter A of the ball is 1.01-1.15,
The ratio of the inner diameter C of the large diameter portion to the ball outer diameter A (C / A) is 1.2 to 3.0,
The thermochromic ballpoint pen, wherein an axial length L from the ball receiving seat to the rear end of the small diameter portion is 3 mm or less. The thermochromic ballpoint pen according to claim 1, wherein the minimum cross-sectional area of the ink passage of the ball receiving seat is 0.003 mm ² or more. 3. The thermochromic property according to claim 2, wherein the rod portion is disposed in the small diameter portion, the taper portion, and the large diameter portion behind the ball, and the rear end and the coil portion of the rod portion are disposed in the ink containing portion behind the ball-point pen tip. Ballpoint pen. A large-diameter portion is press-fitted and fixed to the inner surface of the front end portion of the ink containing portion, and a step portion is formed on the inner surface of the front end portion of the ink containing portion so that the rear end of the press-fitted and fixed large-diameter portion is in contact with the inner diameter of the step portion. The thermochromic ballpoint pen according to claim 3, wherein the thermochromic ballpoint pen is set to be substantially equal to the inner diameter of the rear end of the large-diameter portion. The thermochromic ballpoint pen according to any one of claims 1 to 4, wherein the number of inward protrusions constituting the ball receiving seat is four. The thermochromic ballpoint pen according to any one of claims 1 to 5, further comprising a friction body capable of thermally discoloring the handwriting of the thermochromic ink by rubbing the handwriting of the thermochromic ink.

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