JP2003089294A - Ball point pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve and prevent a ball from falling out of a ball point pen body by means of the water hammer of a shear-thinning ink caused by the falling of a ball point pen and contrive to keep the back-flow preventing function of the shear-thinning ink by a back-flow preventing body composition and to make the leaking-out speed of the shear-thinning ink slower even when the ball happens to come off in order to give a user time to spare for counter- measure and disposition. SOLUTION: A columnar body having grooves for controlling ink flowing rate formed thereon is arranged in an ink tube stored with the shear-thinning ink therein and in an ink circulating hole for communicating with a ball point pen body. At the same time, the charge and position of the back-flow preventing body composition is provided in response to the wetting height of the back-flow preventing body composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called direct liquid type ball-point pen structure using a shear thinning ink, and an ink container for storing the shear thinning ink,
The present invention relates to a ballpoint pen including a ballpoint pen body provided at a tip portion and an ink flow path connecting the ink containing section and the ballpoint pen body.

[0002]

2. Description of the Related Art Heretofore, as an ink container of a ballpoint pen using a relatively high-viscosity ink, a tube structure directly attached to a ballpoint pen body is known as seen in an oil-based ballpoint pen. Since such a product has a small number of parts, is easy to assemble, and has a merit that ink consumption can be easily visually recognized from the outside, in recent years, low-viscosity inks, cosmetics, and correction liquids have been used. Increasingly, it is adopted as a structure of a ball-point pen that discharges such as. With the ink ejection mechanism of these ballpoint pens, the negative pressure of the ink generated when the ink is ejected from the ballpoint pen body causes the ink in the ink storage section to be sucked and moved toward the ballpoint pen body, achieving continuous ink ejection. Is to be done.

Further, in ball-point pens using these low-viscosity inks, since the inks have low viscosities, the inks often flow back and flow out from the rear end portion of the ink storage portion, so that the inks from the ink storage portion are discharged. It is well known that the backflow preventive composition is arranged on the ink interface in order to obtain the above-mentioned backflow prevention function of the ink.

Further, when the diameter of the ink containing portion is large and the area of the ink interface is large, the backflow preventing function of the backflow preventing composition may not be maintained at the position farthest from the inner wall of the ink containing portion. It is also known that a floating body such as a synthetic resin rod-like body is immersed in a layer of the backflow preventive composition.

[0005]

In the case of a relatively high viscosity ink having an ink viscosity range of several thousand to tens of thousands of mP · s, such as an oil-based ballpoint pen ink, even when accidentally dropped on the floor, Due to the large frictional resistance between the inner wall of the ink container and the ink, the impact of the drop is attenuated while it propagates to the ballpoint pen body, and the ink is rotated on the writing surface at the tip of the ballpoint pen body during writing. Although the ball to be transferred is rotatably held and arranged by the ball holding portion, it is rare that the impact causes the ball to fall off.

However, in the case of a relatively low-viscosity ink having a viscosity range of several to several hundred mP · s, since the friction between the ink and the inner wall of the ink container is small, the weight of the ink when dropped is water. There was a problem that the ball of the ball-point pen body fell off as a result of a hit.
A water hammer is a phenomenon in which pressure rises in the pipe due to inertia of the fluid when the fluid flowing in the pipe is stopped by a valve or the like in a short time. In addition, if the ball comes off, in the case of a relatively low-viscosity ink having a viscosity range of several to several hundred mP · s, the ink from the ballpoint pen body may be ejected at a rate of 30 to 40 drops / minute. Leakage occurs, so that the user has no time to deal with and take measures, and as a result, clothes and documents may be contaminated with ink.

This water hammer is not only applied to the side of the ballpoint pen, but also to the backflow preventive composition arranged on the ink interface, so that even if the ball does not fall off,
Since the backflow preventer composition has a high viscosity, it is a liquid or a fluid, so that the backflow prevention function of ink cannot be maintained and ink leakage may occur.

[0008]

That is, according to the present invention, an ink containing portion filled with a shear thinning ink, a ballpoint pen body at a writing tip portion, an air circulating portion at a trailing end portion, the ink containing portion and the ink containing portion are provided. In a ballpoint pen comprising an ink flow path connecting the ballpoint pen body, a columnar body having an ink flow rate control groove on a side surface is fitted inside the ballpoint pen body,
The backflow preventive composition is placed in contact with the interface of the shear thinning ink of the ink containing portion, and the maximum circumscribed circle of the portion of the ink containing portion containing the shear thinning ink is
It is a summary that the backflow prevention composition has a wetting height of not more than twice the material forming the inner wall of the ink containing portion.

The columnar shape is a member having one or more ink flow control grooves formed on the side surface of a solid body, and the cross-sectional shape of the groove can be any shape such as a substantially rectangular shape, a V shape, or a semicircular shape. Can be selected. The method for producing the columnar body can be selected from injection or extrusion molding, and the material is preferably a thermoplastic synthetic resin such as polyoxymethylene resin or polypropylene resin.

The ink flow control groove on the side surface of the columnar body is
The columnar body may have any shape as long as it can ensure ink circulation between the front end portion and the rear end portion, and in addition to the linear groove in the longitudinal direction, the spiral groove formed on the side surface, the longitudinal groove formed on the side surface and the columnar shape. Various shapes such as a groove in which circumferential grooves on the body surface are combined can be appropriately adopted.

Further, the ink containing portion may have any suitable shape such as a cylindrical body having a circular or substantially polygonal cross section or a box-shaped body. When it has a function of displaying the amount and color of the shear thinning ink, it is preferably formed of a material having transparency. Considering the permeability of the shear thinning ink and the ease of molding, An injection or extrusion molded product of polypropylene resin can be preferably used. Further, in order to suppress the adhesion of the shear thinning ink to the inner wall of the ink containing portion, a surface treatment may be performed in which silicone oil or the like is applied to the inner wall of the ink containing portion.

The backflow preventive composition, which is disposed at the interface position of the shear thinning ink, moves following the movement of the interface of the shear thinning ink accompanying the consumption of the shear thinning ink. The optimum value can be set as appropriate depending on the amount of ink discharged and the size of the ink container, but 10,000 mP
A high-viscosity fluid of s to 1,000,000 mP · s can be preferably used from the viewpoints of its followability to the interface of the shear thinning ink, ease of filling, and stability of the interface of the shear thinning ink. One example is polybutene. , Α-olefins, polyα-olefins, silicone oil, petroleum jelly, etc., or a mixture of two or more kinds thereof, and of these, a gelled low molecular weight one having an average molecular weight of 300 to 3700 can be exemplified.

The floating body disposed by being at least partially immersed in the anti-reflux body composition moves together with the anti-reflux body composition, and a material having a specific gravity close to that of the anti-reflux body composition is suitable. used. For example, a rod-shaped body made of synthetic resin such as polypropylene cut to an appropriate length,
Examples thereof include those having a bottomed or non-bottomed ink containing portion shape. It is preferable that the ink container has an outer cross-sectional shape similar to the inner surface of the ink container, because the gap with the inner wall of the ink container can be made constant to some extent.

Here, in order to maintain the backflow prevention function of the shear thinning ink, when the floating body is not used, the maximum circumscribed circle of the portion of the ink storing portion where the shear thinning ink is stored is the backflow preventing agent. The wettability of the composition is not more than twice the height of the material forming the inner wall of the ink containing portion, and when a floating body is used, the width of the gap between the inner wall of the ink containing portion and the outer wall of the floating body is equal to that of the backflow preventing composition. It is less than or equal to the sum of the wetting height for the material forming the inner wall of the ink containing portion and the wetting height for the material forming the outer wall of the floating body of the backflow prevention composition, and the tip of the floating body and the ink interface. It is necessary that the length of the anti-reflux body composition layer which is between is less than or equal to the wetting height of the material of the anti-reflux body composition that forms the outer wall of the tip portion of the floating body. What is "height"? With respect to the direction of gravity, with respect to at the solid surface in the vertical direction, 1.0 cm liquid 0.1cc
The maximum distance in the direction perpendicular to the solid surface between the solid surface after dropping for 1 hour and the surface in contact with the liquid atmosphere. This is schematically shown in FIG. 1, which shows a state after the backflow preventer composition 1 is dropped on the plate P and left standing for 1 hour, and the wetting height corresponds to the distance A.

[0015]

When a shock is applied to the shear thinning ink such as when the ballpoint pen is dropped, a water hammer is caused by the inertia of the shear thinning ink to cause an increase in pressure. This pressure rise advances as a pressure wave inside the ink containing portion, but in the process of reaching the end of the columnar body and proceeding through the ink flow control groove, resistance due to a sharp narrowing of the flow path, As a result, when the ball reaches the ball of the ballpoint pen body, the ball is damped to a pressure weaker than the holding force of the ball holding portion rotatably held.

If the ball should fall out,
When the ballpoint pen is turned downward, the internal shear thinning ink moves downward due to gravity, but the moving speed is weakened by the resistance force when passing through the ink flow control groove on the side surface of the columnar body, and the shear thinning viscosity is slow. Ink leaks.

Furthermore, the "wetting height" of the anti-refluxing body composition which is a high viscosity fluid is an index showing the hardness of the high viscosity fluid, and is the adhesion maintenance property to the material in contact, that is,
It can be said that this represents the range in which the movement of the backflow preventive composition is greatly affected by the wall surface. The backflow preventive composition in the range of "wetting height" with respect to the wall surface is restricted from freely moving away from the wall surface, and can sufficiently exert the interface maintaining function for the shear thinning ink, and can be subjected to loads such as vibration and impact. However, it is sufficient to suppress problems such as liquid leakage as much as possible.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example will be described below with reference to the drawings. The one shown in FIG. 2 is an example of a so-called raw ink type ballpoint pen in which the ink in a free state is accommodated in the inside which is not held by the ink occlusion body such as the fiber bundle. The ballpoint pen tip 2 which is a ballpoint pen body is not directly fixed to the ink cylinder 3 but is fixed via a chip holder 4 fixed to the tip of the ink cylinder. The ink cylinder 3 is an injection-molded product of polypropylene resin having excellent gas impermeability and transparency, and the remaining amount of the shear thinning ink 5 is visible. In the outer peripheral portion on the tip side of the ink cylinder 3,
A concave portion 3a as a small diameter portion is formed, and a tubular grip 6 made of an ethylene elastomer is attached. The grip 6 has a step portion 3b which is a rear end portion of the recess 3a.
The ball-point pen tip 2 is clamped by the rear end of the tip holder 4 to which the tip 2 is fixed, and is positioned. With the grip 6 attached, the grip 6
The inner diameter of the ink cylinder 3 is close to the outer diameter of the ink cylinder 3, and the inner diameter of the ink cylinder 3 is small in the range in which the grip 6 is arranged so that the thickness of the wall of the ink cylinder 3 does not have to be thin. It is a division. By the way, including the small diameter part due to the fixing of the chip holder 4, 4.0 mm, 5.5 mm from the tip side,
It has an inner diameter of 7.0 mm.

At the rear end opening of the ink cylinder 3, a tail plug 7 made of polypropylene resin colored or dyed with the color of the shear thinning ink 5 which can be displayed in color is press-fitted and fixed, and the shear thinning viscosity is reduced. The interior of the ink 5 is partitioned. The tail plug 7 has a vent hole 7a as an air flow passage.
Is formed, and outside air is supplied to the back portion of the backflow preventer composition 1 and the floating body 8 which will be described later in the ink cylinder 3 as necessary.

As shown in FIG. 3 which is an enlarged view of the I portion of FIG. 2, FIG. 4 which is an enlarged side view of a columnar body 9 which will be described later, and FIG. 5 which is an enlarged sectional view, the ink circulation hole 2a of the ballpoint pen tip 2 is shown. A columnar body 9 formed by injection molding of a columnar polyoxymethylene resin having two vertical grooves 9a for controlling the ink flow rate having a substantially rectangular cross section on the side surface is press-fitted and fixed. As a result, when a shock is applied to the shear thinning ink 5 when the ballpoint pen falls, the shear thinning ink 5
Due to the inertia of the ink, a water hammer occurs, causing an increase in pressure, and a pressure wave that travels inside the ink cylinder 3, but the columnar body 9
When the ball 10 of the ball-point pen tip 2 reaches the ball 10 as a result of the resistance caused by the abrupt narrowing of the flow path in the process of reaching the end of the ball and advancing in the vertical groove 9a, the ball 10
Is damped to a pressure weaker than the holding force of the ball holding portion 2b held rotatably, so that the ball 10 comes off the ball holding portion 2b, and the ball pen tip 2 moves to the ball 1
It is designed to suppress the loss of 0 as much as possible. Further, if the ball 10 falls off, the internal shear thinning ink 5 moves downward by gravity when the ballpoint pen tip 2 is directed downward, but passes through the vertical groove 9a on the side surface of the columnar body 9. The movement speed is weakened by the resistance force at the time of the movement, and the shear thinning viscosity ink 5 leaks slowly, the user notices that the ball 10 has fallen off, and there is ample time to deal with and deal with it. It is possible to prevent contamination of documents and documents.

The shear thinning ink 5 in the ink cylinder 3
The anti-reflux body composition 1 and the floating body 8 immersed in the anti-reflux body composition 1 are arranged in contact with the interface portion of 1. The backflow preventer composition 1 is polybutene gelled with a gelling agent, and the wetting height of the backflow preventer composition 1 to the polypropylene resin forming the ink cylinder 3 is set to 3.
It is set to be 4 mm. It is possible to use a composition that exhibits hard physical properties such that the height of wetting becomes high,
On the contrary, the advantages of the fluid such as the followability to the interface of the shear thinning ink 5 and the closeness to the interface of the shear thinning ink 5 may be impaired. The floating body 8 is immersed.

The distance between the tip of the floating body 8 and the interface of the shear thinning ink 5 is not more than the above-mentioned wetting height of 3.4 mm, and the gap between the inner wall of the ink cylinder 3 and the outer wall of the floating body 8 is 3. It is contained within 4 mm, and the backflow preventer composition 1 is present within a range of 3.4 mm from each wall surface of the inner wall of the ink cylinder 3 and the outer wall of the floating body 8. By placing the floating body 8 by immersion. In addition, the shear thinning ink 5 does not include the backflow preventer composition 1 that can move freely regardless of the wall surface.
It is possible to prevent the leakage of water.

Corresponding to the change in the inner diameter of the ink cylinder 3 depending on the position in the longitudinal direction, the shape of the floating body 8 is also made up of a rear large diameter portion and a front small diameter portion. By the way, the outer diameter of the larger diameter is 6.8 mm, and the smaller diameter is 5.3 mm. In the portion of the ink cylinder 3 having the inner diameter of 5.5 mm, the backflow preventing function is sufficiently exerted by the backflow preventing composition 1 having a wetting height of 3.4 mm, and thus the floating body 8 is not required in that portion. Therefore, as shown in FIG. 6, which shows a state in which the shear thinning ink 5 is reduced. At the boundary step portion from the large-diameter portion of the inner diameter of the ink cylinder 3, the floating body 8 abuts on this step and stays there. In addition, a plurality of ribs 3 are provided on this step.
c is formed so that the floating body 8 does not hinder the supply of air into the ink cylinder 3 in front of the step.

Further, the reason why the small diameter portion is provided on the floating body 8 is that when the floating body 8 having an outer diameter of 6.8 mm over the entire length is adhered and remains on the inner wall of the ink cylinder 3 as the backflow preventing composition 1 moves. Considering the amount of increase, 0.2 cc is required, but the distance between the interface of the shear thinning ink 5 and the tip of the floating body 8 is required to be 5.0 mm. However, the floating body 8
Since the backflow preventer composition 1 has a wetting height of 3.4 mm with respect to the polypropylene resin, which is the material of (3), the adhesion cannot be maintained. This is because by providing the floating body 8 with a small diameter portion, the volume of the backflow prevention composition 1 is increased, and the distance between the floating body 8 and the interface of the shear thinning ink 5 falls within the range of the wetting height. The viscosity of the anti-reflux body composition 1 was 430000 mP · s,
Handwriting width 0.25 in continuous writing with a writing load of 100 g
mm ~ 0.35 mm, 0.10 g per 100 m ~
When ejecting 0.15 g of the shear thinning viscosity 5 ink, about 0.8 mm with respect to the movement of the interface of the shear thinning viscosity ink 5
It is set to follow and move in / min. This is a setting for the head pressure when the diameter of the ink cylinder 3 is 7.0 mm, and the head pressure is lower at the point where the diameter of the ink cylinder 3 is 5.5 mm than when it is 7.0 mm. Nevertheless, since it is necessary to maintain the same discharge as that at the time of 7.0 mm, the movement resistance of the backflow preventer composition 1 is weakened.

7 to 9 show another example of the columnar body 9 corresponding to FIGS. 3 to 5. The present example is a columnar body 9 of an extrusion molded body, in which molten polyoxymethylene resin is extruded from an extrusion molding nozzle (not shown) having three protrusions around a circular hole, and the axis is It is obtained by taking it out by a roller rotating in the center, polishing the outer diameter to a predetermined size with a centerless polishing machine, and cutting it into a predetermined length. The ink flow rate is controlled on the side surface of the columnar body 9. Three spiral outer grooves 9b are formed. Since the outer groove 9b has a spiral shape that does not communicate in the same direction as the longitudinal direction of the ink cylinder 3, for example, the linear vertical groove 9a communicating in the longitudinal direction as shown in FIG. 2 described above. Compared with, the resistance against the water hammer applied in the longitudinal direction can be obtained more strongly, and the drop of the ball 10 from the ball-point pen tip 2 can be suppressed more reliably, and the shear thinning viscosity can be reduced. The resistance against the hydraulic head pressure applied in the longitudinal direction of the ink 5 is larger than that of the linear vertical groove 9a communicating in the longitudinal direction, so that the shear thinning viscosity ink 5 moves in the outer groove 9b. When the ball 10 falls off from the ball-point pen tip 2, the leak speed of the shear thinning ink 5 from the ball-point pen tip 2 can be further slowed down, and the user's time margin is further increased. Can That.

FIG. 10 shows another example. As compared with the example shown in FIG. 2, the filling amount of the shear thinning ink 5 is 1.2 times larger in order to increase the writing distance. When the same anti-reflux body composition 1 as in the example of FIG. 2 is used and the amount of the anti-reflux body composition 1 is 1.2 times, the shear thinning ink 5 of The distance between the interface and the floating body 8 is 4.0 mm, which exceeds the wetting height of 3.4 mm of the backflow preventer composition 1, but by providing the floating body 8 with a small diameter portion, The volume of the backflow preventer composition 1 is increased so that the distance between the floating body 8 and the interface of the shear thinning ink 5 is kept within the above-mentioned wetting height of 3.4 mm or less.

FIG. 11 shows another example. 2 is similar to the example shown in FIG. 2, but the wetting height of the backflow preventer composition 1 to the polypropylene resin, which is the material of the floating body 8, is 6.
Since it is 2 mm, even if the floating body 8 has an outer diameter of 6.8 mm over its entire length as in the present embodiment, the distance between the interface of the shear thinning ink 5 and the tip of the floating body 8 can be maintained at 5.0 mm. . The backflow preventer composition 1 has a viscosity of 100500 mPs, and a handwriting width of 0.25 mm to 0.35 mm in continuous writing with a writing distance of 100 g.
When 0.10 g to 0.15 g of the shear thinning ink 5 is ejected per 100 m, the shear thinning ink 5 moves to follow the movement of the interface of the shear thinning ink 5 at about 0.8 mm / min. The backflow preventer composition 1 alone is about 1.6 m
Since the shear thinning ink 5 is excessively ejected by following the m / min, the floating body 8 is arranged as a resistor in the movement of the backflow prevention composition 1.

FIG. 12 shows another example. In this example,
The ball-point pen tip 2 directly on the tip opening of the ink cylinder 3,
The ink cylinder 3 is press-fitted and fixed, and the portion of the ink cylinder 3 in which the shear thinning ink 5 is stored has a substantially cylindrical shape with an inner diameter of about 3 mm.

The backflow preventer composition 1 is arranged in contact with the interface portion of the shear thinning ink 5 of the ink cylinder 3.
The backflow preventer composition 1 is polybutene gelled with a gelling agent, and is arranged at 0.12 cc. The backflow preventer composition 1 was prepared by adjusting the hardness so that the wetting height of the polypropylene forming the ink cylinder 3 with respect to the resin was 2.0 mm.
The free movement is restricted within a range of 2.0 mm from the inner wall surface of the ink, and the holding effect by the inner wall facing each other is overlapped by filling the ink cylinder 3 having the inner diameter of 3.0 mm in a layered manner. The backflow preventer composition 1 is prevented from separating and moving from the inner wall surface even when subjected to a load such as a shock or an impact, and is prevented from causing leakage of the shear thinning ink 5. The viscosity of the backflow preventive composition 1 of this example was set to 15000 mPs, and the handwriting width was 0.
25 mm to 0.35 mm, 0.10 per 100 m
The viscosity is set so as to move following the moving speed of the interface of the shear thinning ink 5 with respect to the discharge of the shear thinning ink 5 of g to 0.15 g. This is an example, and the viscosity of the backflow preventer composition 1 should be appropriately set depending on the actual specifications, the inner diameter of the ink cylinder 3, the head pressure, the type of the shear thinning ink 5, and the like. For example,
When it is desired to adjust the backflow preventive composition 1 so as to follow the interface of the shear thinning viscosity ink 5 at about 1.5 mm / min, the viscosity of the shear thinning viscosity ink 5 is set to 10000 mP · s and the leakage of the shear thinning viscosity ink 5 is prevented. In order to prevent this, by applying silicon to the inner wall surface of the ink cylinder 3 and providing a silicon layer, the backflow preventer composition 1 is subjected to lipophilic treatment so that the wetting height is increased. Further, it is possible to further suppress the leakage of the shear thinning ink 5. The formation of the silicon layer can be performed simultaneously with the simple coating, when the ink cylinder 3 is extrusion-molded.

[0030]

EFFECTS OF THE INVENTION As a test for confirming the effect, a columnar body as shown below is prepared, and a ball-point pen sample in which such a columnar body is housed and tested is as follows.
The following evaluation test was performed using the one shown in FIG.

Columnar body 1 (three-groove injection-molded product) A columnar columnar body has a surface with a width of 0.2 mm and a depth of 0.11 mm.
A columnar body 1 was obtained by injection-molding a polypropylene resin into three cast bodies having axial grooves each having a substantially rectangular cross section formed at an angle of 120 degrees from the center of the cylinder.

Columnar body 2 (two-groove injection molded product) A columnar columnar body has a surface with a width of 0.3 mm and a depth of 0.11 mm.
A columnar body 2 was obtained by injection-molding a polyoxymethylene resin into a cast body in which two axial grooves having a substantially rectangular cross section were formed at an angle of 180 degrees from the center of the cylinder.

Columnar body 3 (three-groove extrusion molded product) A molten polyoxymethylene resin is extruded and taken out from an extrusion molding nozzle (not shown) having three protrusions around a circular hole, and its outer diameter is adjusted. By polishing to a predetermined size with a centerless polishing machine and cutting it to a predetermined length, three axial linear grooves with a cross-sectional area of 0.03 mm2 are formed on the outer surface at an angle of 120 degrees from the center of the cylinder. The cast body 3 thus obtained was obtained.

Columnar body 4 (spiral three-groove extrusion product) Molten polyoxymethylene resin is extruded from an extrusion molding nozzle provided with three protrusions around a circular hole,
A cross-sectional area of the outer surface is 0.03mm
A cast body 4 was obtained in which three spiral grooves 2 in the axial direction were formed at an angle of 120 degrees from the center of the cylinder.

As a comparative example, a conventional ballpoint pen structure in which the columnar body as in the present invention is not used in the ink circulation hole of the ballpoint pen tip was used. (See Figure 13)

Table 1 shows the settings of each example and comparative example.

[0037]

[Table 1]

The test samples of Examples 1 to 4 and Comparative Example were tested. The results are shown in Table 2. (1) Dropping Ball Dropping Durability Test Each ballpoint pen from which the cap was removed was successively increased in drop height and dropped onto the concrete floor in the horizontal direction, and the drop height at which the ball of the ballpoint pen tip fell off was recorded. (2) Ink leak rate test when the ball falls off When the ball fell off, the ink leak rate was measured with the pen tip facing downward. Leak rate is 1
It was recorded by the weight of the ink leaked per minute.

[0039]

[Table 2]

The ballpoint pen tip and the ball diameter of the ballpoint pen used in the test are as follows. Pentel Co., Ltd. synthetic resin tip ballpoint pen B50 tip, ball diameter: 0.8 mm Tip material: polyoxymethylene resin (trade name: Delrin)

The composition of the shear thinning ink used in each test is as follows. Water Black # 108-L (14% aqueous solution of CI DIRECT BLACK19, manufactured by Orient Chemical Industry Co., Ltd.) 40.0 parts Kerzan AR (xanthan gum, shear thinning resin, manufactured by Sansho Co., Ltd.) 0.2 Parts Ethylene glycol 10.0 parts Glycerin 10.0 parts Ion-exchanged water 39.0 parts Benzotriazole 0.5 parts Proxel GXL (1,2-benzisothiazolin-3-one, preservative, ICI Co., Ltd.) 0 .3 parts Kerzan AR and water in the above ingredients in a lab mixer 3
The solution was stirred for 0 minute to dissolve it uniformly to prepare an aqueous solution of Kerzan. The remaining components were added to this, and the mixture was further mixed and stirred for 2 hours to obtain a viscosity of 60 mPa · s at a shear rate of 10 sec-1.
Of black ink was obtained. This one has a shear rate of 380se
The viscosity at c-1 was 25 mPa · s.

As described above, according to the present invention, the water hammer effect generated when the ballpoint pen containing the shear thinning ink is dropped is attenuated by passing through the ink flow rate control groove.
The ball pen body is prevented from falling off as much as possible, and even if the ball comes off, the speed at which the shear thinning ink leaks from the ball pen body can be slowed down to the extent that the user can handle it. is there.

Further, the backflow preventive composition in the range of "wetting height" with respect to the wall surface is restricted from freely moving away from the wall surface, and can sufficiently exhibit the interface maintaining function for the shear thinning ink and vibrate. It is possible to obtain a device that suppresses problems such as liquid leakage as much as possible against loads such as shock and impact.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining “wetting height”.

FIG. 2 is a vertical sectional view showing an example.

FIG. 3 is an enlarged view of part I in FIG.

FIG. 4 is an enlarged side view of a columnar body 9.

FIG. 5 is an enlarged cross-sectional view of a columnar body 9.

FIG. 6 is a vertical cross-sectional view showing the state in use of FIG.

FIG. 7 is a view corresponding to FIG. 3 showing another example.

FIG. 8 is a view corresponding to FIG. 4 showing another example.

FIG. 9 is a view corresponding to FIG. 5 showing another example.

FIG. 10 is a vertical cross-sectional view showing another example.

FIG. 11 is a vertical sectional view showing still another example.

FIG. 12 is a vertical sectional view showing still another example.

FIG. 13 is a view corresponding to FIG. 3 showing a comparative example.

[Explanation of symbols]

A wet height P plate 1 Backflow prevention composition 2 ballpoint pen tip 2a Ink circulation hole 2b ball holder 3 ink cylinder 3a recess 3b step 3c rib 4 chip holder 5 Shear thinning ink 5a vent 6 grip 7 tail plug 7a Vent hole 8 floating bodies 9 columns 9a vertical groove 9b outer groove 10 balls

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Claims (5)

[Claims] 1. An ink storage part filled with shear thinning ink, a ballpoint pen body at a writing tip, an air circulation part at a rear end, and an ink flow passage connecting the ink storage part and the ballpoint pen body. In the ball-point pen, the backflow prevention composition is placed in contact with the interface of the shear thinning ink of the ink containing portion, and the maximum circumscribed circle of the portion of the ink containing portion containing the shear thinning ink is A ball-point pen characterized by having a wetting height of the backflow preventer composition which is not more than twice the height of the material forming the inner wall of the ink containing portion. 2. An ink container filled with a shear thinning ink, a ballpoint pen body at a writing tip, an air circulation unit at a rear end, and an ink flow passage connecting the ink container and the ballpoint pen body. In the ball-point pen, the backflow preventive composition is brought into contact with the interface of the shear thinning ink in the ink containing section, and the floating body at least partly immersed in the backflow preventive composition is arranged. The width of the gap between the inner wall and the outer wall of the floating body is the wetting height of the backflow prevention composition to the material forming the inner wall of the ink containing portion and the wetting height of the backflow prevention composition to the material forming the outer wall of the floating body. And the length of the backflow preventing composition layer between the tip of the floating body and the interface of the shear-thinning ink is equal to or less than the outer wall of the tip of the floating body of the backflow preventing composition. form A ball-point pen whose wet height is less than or equal to the material to be formed. 3. The ballpoint pen according to claim 1, wherein a columnar body having an ink flow rate control groove on a side surface is fitted inside the ballpoint pen body. 4. The material forming the inner wall of the ink containing portion is polypropylene resin.
The ballpoint pen according to claim 3. 5. The material forming the inner wall of the ink containing portion is a silicone oil layer applied to the inner wall of the ink containing portion. Ballpoint pen.