JP5830849B2 - Writing instrument - Google Patents

Description

  The present invention relates to a temporary ink in which ink is stored in an ink tank in a free state, and a pen tip to which ink is supplied from the ink tank, and ink corresponding to an increase in internal pressure of the ink tank can be temporarily stored. The present invention relates to a writing instrument in which a reservoir is arranged.

  Rather than impregnating and holding ink in an ink occlusion body such as a fiber converging body, the so-called raw ink-type writing instrument in which ink is stored in an ink tank in a free state is a writing sustainability by the amount of ink that can be stored abundantly, ink Due to the advantages such as visual recognition of the remaining amount and fresh handwriting, it is also widely used as a writing instrument such as a ballpoint pen, line marker, marking pen, fountain pen, and an applicator or makeup tool using a brush.

Since the ink in the ink tank of such a raw ink type writing instrument is in an unconstrained state in a free state, it is pushed out of the ink tank by the expansion of air in the ink tank due to environmental changes such as decompression and temperature rise. Ink flows out from the nib and leaks.
In order to suppress ink leakage from the pen tip, the ink pushed out of the ink tank is made of a synthetic resin injection molded product with a comb-like longitudinal cross section using a capillary phenomenon, or a fiber converging body. Can be stored in a temporary ink reservoir between the ink tank and the nib (Patent Documents 1 and 2), or without using the temporary ink reservoir, the pressure inside and outside the ink tank directly A differential pressure valve that enables the differential to operate by the differential pressure is arranged, and the expanded air that pushes ink out of the ink tank is discharged from the ink tank to the outside air, thereby suppressing ink leakage from the pen tip. What was made (patent document 3) is known.

JP 2008-183895 A JP 2001-171285 A JP 2006-168163 A

However, in the invention described in Patent Document 1, since it is a temporary ink reservoir that has a volume of 40% or more of the ink tank volume, it looks large as a whole writing instrument. In addition, the larger the ink tank volume, the larger the air volume in the ink tank when the ink is reduced, so the expansion volume of air due to environmental changes increases and the amount of ink pushed out of the ink tank increases. Therefore, although the ink tank volume is more than twice that of the temporary ink reservoir, the ink tank accommodates the temporary ink reservoir against the volume of the ink tank and possible environmental changes. Only about 40% to 50% of the ink tank volume, about 20% to 30% of the entire writing instrument, and it can not be accommodated abundantly. As a result, there was a problem that the writing distance was shortened, and the characteristic point of writing sustainability as an original raw ink type writing instrument was impaired.
In addition, since the invention described in Patent Document 2 is in a temporary ink reservoir of about 10 to 30% of the ink tank volume, it eliminates the fact that the amount of ink to be stored is reduced. An ink occlusion body is arranged in the portion. Although the volume in the ink tank does not change in appearance, the amount of ink that has been impregnated by the ink occlusion body in order to reduce the volume in the ink tank is substantially increased. However, the amount of ink as a raw ink-type writing instrument that is not constrained in a free state cannot be changed, and the features of visual recognition of the remaining amount of ink and fresh handwriting as an original raw ink-type writing instrument are impaired. There was a problem.
Furthermore, the invention described in Patent Document 3 opens when the air in the ink tank is expanded by the differential pressure valve, and discharges the expanded air from the ink tank to the outside air. Since the differential pressure valve opens and closes due to the difference, the pressure in the ink tank is also applied to the pen tip side until the predetermined pressure difference is reached, causing ink leakage from the pen tip. there were.
In addition, since the differential pressure valve as a writing instrument is used by manually gripping the shaft cylinder portion that becomes the ink tank that contains ink inside, the air in the ink tank expands due to the body temperature from the hand, causing ink leakage. In order to obtain the followability of writing, it is considered that outside air flows into the ink tank to compensate for the slightly reduced pressure in the ink tank according to the small amount of ink discharged from the writing instrument. Te, pen type and, although the upper and lower slightly due specification for writing instruments _durability, set to open at a slight pressure difference 0.5mmH 2 O~5.0mmH about ₂ O, closing the differential pressure valve The operation is generally performed instantaneously due to the blockage by opening the air by a pressure difference between the air and the accompanying external air, and discharging the air to the air. .
However, even if the opening / closing operation is instantaneous, the time difference of the opening / closing operation cannot be completely eliminated, and thus a slight pressure in the ink tank is applied to the pen tip side. When a slight pressure is applied, the ink moves to the pen tip in a very small amount, so that the ink leaks to the extent that ink drops from the pen tip immediately after opening and closing the differential pressure valve once. However, the instantaneous opening / closing operation of the differential pressure valve is repeated as long as the environmental change continues, so that a small amount of ink that has moved to the nib will eventually accumulate. As a result, ink leaks from the pen tip, and simply adjusting the differential opening / closing operation of the differential pressure valve has not solved the problem of causing ink leak from the pen tip.

The present invention accommodates ink in an ink tank in a free state, the pen tip to which the ink is supplied from the ink tank, and the ink for the internal pressure increase of the ink tank can be temporarily accommodated. A writing instrument having a temporary ink reservoir, wherein an ink valve that is operable by a pressure difference between the inside and outside of the ink tank is directly connected to the ink tank , and the ink valve is connected to the ink tank. The ink accommodated in the ink tank is supplied to the inside and outside communication holes of the ink tank to operate , the ink tank is disposed between the ink valve and the nib, and the ink tank is disposed between the ink valves the temporary ink reservoir portion, further, the ink-repellent filter is arranged behind the ink valves, ink guiding core supplying ink to said nib, With projecting from serial ink valve in front of the temporary ink reservoir, the storage volume of the ink, it is an gist writing instrument that less than 50% of the fill volume of the ink accommodated in the ink tank .

Depending on the specifications for environmental changes, ink type, solvent content, physical properties such as viscosity and surface tension, wettability between ink and ink tank, ink filling volume, open / close capacity of differential pressure valve, etc. The amount of ink leakage caused by the accumulation of a small amount of ink due to the momentary and repeated opening / closing operation of the differential pressure valve due to a slight pressure difference inside and outside the ink tank is 1% to 45% of the ink filling volume. In particular, in the case of a general water-based ink containing water as a main solvent or an oil-based ink containing ethanol as a main solvent and having a low viscosity of about 1 to 100 mPa · s, these are about 3% to 30%. Since the temporary ink reservoir having a volume that can accommodate the ink of the ink is disposed, ink leakage from the pen tip can be suppressed.
In addition, since the differential pressure valve in the writing instrument operates with a predetermined slight pressure difference between the inside and outside of the ink tank, the pressure in the ink tank is higher than the minute pressure regardless of the amount of air in the ink tank. Since the pressure does not rise and a substantially constant pressure state can be maintained, the ink tank can store an amount of ink that can be stored and filled in the assembly.
Further, by setting the ink storage volume of the temporary ink reservoir to less than 50% of the ink filling volume that can be accommodated in the ink tank, at least about 70% of the total becomes the ink filling volume, It will give you a writing instrument that contains ink that is not constrained in a free state, both in appearance and in practice, and has the advantages of writing sustainability as an original raw ink type writing instrument, visual recognition of the remaining ink level, and fresh handwriting be able to.

The longitudinal cross-sectional view which shows an example. The I section enlarged view of FIG. II-II 'transverse cross-sectional view of FIG. The longitudinal cross-sectional view which shows another example. The longitudinal cross-sectional view which shows the pen tip upward state of the example of FIG. The longitudinal cross-sectional view which shows a prior art example.

The writing instrument of the present invention contains ink in an ink tank in a free state, and the ink tank is depressurized by ink discharge from the pen tip connected to the ink in the ink tank, or the ink tank is in an environmental temperature rise. Can be suitably used in writing instruments that allow the inside of the ink tank to communicate with the outside air according to the pressure increase state of the ink tank, and applicators or cosmetics that contain and discharge liquids that are physically similar to the ink in the writing instrument It is.

As the ink stored in the ink tank of the writing instrument, water-based inks containing water as the main solvent, oil-based inks containing organic solvents such as isopropyl alcohol and ethanol, dyes, pigments, or both as the colorant are used. It can be used regardless of what you have done. In particular, when developing applications for writing instruments such as ballpoint pens, line markers, marking pens, fountain pens, brush pens, ink storage capacity in temporary ink reservoirs, and ink valves formed by the capillary action of ink, Considering the ease of supplying ink to the ink valve, a relatively low viscosity such that the ink viscosity is 1 to 100 mPa · s (B-type viscometer No. 3 rotor, 60 rpm, 25 ° C.) is good. is there.

  The pen tip used for the writing instrument is a fiber converging body in which polyethylene terephthalate fiber, polyamide fiber, and polyacrylonitrile fiber are converged with an adhesive, processed into an appropriate shape by grinding and cutting, and cured by heat treatment after injection molding. Sintered body, polyacetal, etc. are formed by extrusion molding, so-called resin pen tip, stainless steel pipe is cut, and the coated surface is polished and coated thin tube pipe, synthetic resin injection molded product and stainless steel etc. are cut After that, a fountain pen nib that is formed by punching or bending a base material selected from a ballpoint pen tip, gold, gold alloy, stainless steel, etc. with a ball held at the tip is bundled with a brush made of synthetic resin, etc. Examples of brush heads.

The ink tank used for the writing instrument is not particularly limited as long as it does not cause a change in shape due to reaction due to swelling, melting, dissolution, decomposition, etc., relative to the ink contained therein, polypropylene, polyethylene, Synthetic resins such as polyethylene terephthalate, polyamide, polyethylene naphthalate, polybutylene terephthalate, polyacetal, polycarbonate, polystyrene, ethylene / vinyl alcohol copolymer, polymethacrylate, etc. It can be used as appropriate. For example, with water-based inks that use water as the main solvent and oil-based inks that use organic solvents such as isopropyl alcohol and ethanol as the main solvent, reactivity with ink, ink weight loss due to ink evaporation inside the ink tank, price, and molding In view of the properties, general-purpose synthetic resins such as polypropylene and polyethylene are suitable. Further, since the writing instrument of the present invention is a so-called raw ink type writing instrument that stores ink in an ink tank in a free state, considering that the remaining amount of ink can be visually recognized from the outside, a transparent or translucent synthetic resin and It is desirable to do. In addition, as a molding method of the synthetic resin, injection molding, extrusion molding, blow molding, or the like can be used as appropriate.

The differential pressure valve used for the writing instrument may be any one that can be opened and closed by momentary fine movement according to the body temperature by gripping the hand during use or the amount of ink discharged in writing, i.e., the tip of the pen tip. type and, although the upper and lower slightly due specifications for durability of the writing _instrument, open at fine pressure difference 0.5mmH 2 O~5.0mmH about ₂ O, an opening, a slight air produce a minute pressure difference When the ink is discharged and the differential pressure valve continues to open, ink leakage is caused by the pressure head of the ink.
As a differential pressure valve, a rubber valve such as an elastomer or the like is provided with a slit opening / closing part of one or ten letters, or a part that becomes a communication hole inside and outside the ink tank is used as a valve seat. A spring valve provided with a valve that closes, a liquid that forms a liquid film by the capillary action caused by the capillary force generated between the liquid such as ink and the communication hole inside and outside the ink tank, and the liquid that is interposed in the communication hole There is a liquid valve that opens by pushing a small pressure difference. Furthermore, since the liquid valve always generates a capillary force of the liquid with respect to the communication hole, the pressure difference disappears at the same time as the inside of the ink tank, and the communication hole can be closed instantaneously. It is only necessary to set the amount of liquid and the capillary force of the liquid intervening in the communication hole, a slit valve that requires the friction resistance of the opening and closing part, the overlap of the opening and closing part, and the accuracy of the elastic force and dimensions, and the minimum wire diameter and load Compared to a spring valve that requires accuracy, a liquid valve is most suitable as a differential pressure valve in consideration of operability and ease of formation. In particular, in the case of liquid valves, the ink stored in the ink tank is supplied to the internal and external communication holes of the ink tank in consideration of the maintenance of the properties of the liquid used for the valve, the supply and storage means, and the cost of these means. More preferably, the ink valve is adapted to operate.
One of the ink impregnation means for supplying the ink stored in the ink tank to the internal and external communication holes in the ink valve is in contact with the ink stored in the ink tank, and the other is the communication hole. As long as it is possible to supply ink from the ink contained in the ink tank to the communication hole, the strength of the capillary force is not limited. For example, polyethylene terephthalate fiber, polyamide fiber, polyacrylonitrile fiber can be used as an adhesive. Examples thereof include those obtained by processing the fiber converging body converged by the above by grinding and cutting into a suitable shape, a sintered body cured by heat treatment after injection molding, a thin tube formed by extrusion molding of polyacetal and the like. In addition, it may be an ink impregnation means for supplying ink in the ink tank to the liquid film by forming slit-like capillary grooves on the inner wall surface of the ink tank, rather than a fiber converging body having capillary force or a capillary tube by extrusion molding. Further, it is possible to reduce the cost by reducing the number of parts. In addition, the slit-like capillary groove on the inner wall surface of the ink tank may be formed by forming a concavo-convex state on the surface or by processing after molding so that the ink is easily wetted depending on the capillary state of the ink. .

As a temporary ink reservoir used for writing instruments, ink is not always stored, and when the air inside the ink tank expands due to environmental changes due to temperature rise or pressure drop, the differential pressure valve instantaneously and repeatedly It is only necessary that a small amount of ink flowing out of the ink tank can be stored before it leaks from the pen tip by the opening / closing operation, for example, comb-shaped synthetic resin molding that can store ink by capillary force between the comb teeth In order to improve the ink storage capacity of the resin surface of this product and the comb-shaped synthetic resin molded product, the surface of the comb-tooth is rough or rough, and it has an affinity with the main solvent of various inks. Examples thereof include those having been subjected to an ink-philic treatment with a certain powder or solvent, or using an ink occlusion body comprising a fiber converging body or a sintered body. Specific examples of the parent ink treatment include those obtained by dispersing and applying silica powder with isopropyl alcohol. In addition, as a product made of a comb-shaped resin molded product, acrylonitrile butadiene styrene copolymer, polyacetal, or the like is suitable as a synthetic resin in view of extremely narrow comb-shaped moldability. As a temporary ink reservoir using an ink occlusion body, a polyethylene fiber terephthalate fiber, a polyamide fiber, a polypropylene fiber, a polyacrylonitrile fiber, or the like is converged by melting an adhesive or a fiber having a different melting point, or urethane. Examples thereof include a continuous porous body in which continuous pores are formed by foaming or elution of a synthetic resin, and a granular aggregate in which synthetic resins such as polyethylene terephthalate, polypropylene, and polyethylene are deposited in the form of small spheres or powders. In particular, the temporary ink reservoir using an ink occlusion body has a stronger capillary force at the portion where the ink is stored than the comb-shaped synthetic resin molded product, and therefore does not require any treatment such as surface modification. In addition, oil-based inks using an organic solvent such as isopropyl alcohol or ethanol as a main solvent can be used, and assembly is simple and relatively inexpensive, which is preferable.
Furthermore, in the temporary ink reservoir using a comb-shaped synthetic resin molded product, it is necessary to arrange an ink guiding member for supplying ink from the ink tank to the pen tip. There is no necessity to use a hollow ink occlusion body in the ink reservoir, for example, the ink occlusion body is compressed at the coaxial position from the ink tank side and the pen tip side, and an ink guiding part is provided on a part of the ink occlusion body. It is possible to form a high-density portion, which is preferable in terms of the number of parts and price.

  Hereinafter, an example will be described with reference to the drawings. In order to make it possible to visually recognize the remaining amount of ink 1 from the outside, the one shown in FIG. Dissolve the black dye, and free the water-based ink 1 having a surface tension of 35.0 mN / m and a low viscosity of 2.5 mPa · s (B-type viscometer No. 3 rotor, 60 rpm, 25 ° C.). This is an example of a so-called ball-point pen that contains 10 cc and has a pen tip 3 made of a ballpoint pen tip 3a connected to the tip. The surface tension of the ink 1 is 20 mN / m in consideration of the penetrability to the pen tip 3, the discharge property, the blot of the handwriting, and the interposition of the ink 1 in the ink valve formation groove 4 a of the differential pressure valve member 4 described later. -60 mN / m is preferable.

In order to supply the ink 1 to the nib 3, an ink guide core 5 having a porosity of 66%, which is made of a fiber converging body of polyethylene terephthalate fiber that connects the ink 1 of the ink tank 2 and the ballpoint pen tip 3 a is disposed. Yes.
As shown in FIG. 2, which is an enlarged view of the I part of FIG. 1, a tail plug 6, which is an injection-molded product made of polypropylene, is press-fitted into the back of the ink tank 1, and further, on the inside of the tail plug 6, Similar to the tail plug 6, a differential pressure valve member 4 which is an injection-molded product made of polypropylene is press-fitted and the ink guide core 5 has a hole 7a in a comb-like temporary ink reservoir 7 described later. Further, it passes through the ink 1, passes through the hole 4 b of the differential pressure valve member 4, extends to the top surface 6 a of the tail plug 6, and is fixed in contact with the top surface 6 a.
In addition, although the ink guide core 5 in this example is a single one extending from the tip side to the pen tip 3 and the rear end side to the differential pressure valve member 4, the supply property of the ink 1 to the pen tip 3 and When the ink tank 2 is different in the ink valve formation groove 4a of the differential pressure valve member 4 to be described later, or when the ink tank 2 can be removed by making the ink tank 2 into a cartridge, etc. 3 and the ink guide core 5 may be disposed on the differential pressure valve member 4, respectively. In addition, the differential pressure valve member 4 and the tail plug 6 are formed as separate parts in consideration of the ease of forming the mold of the ink valve forming groove 4a formed in the differential pressure valve member 4 and the moldability. May be.

An ink valve forming groove 4a is formed on the side of the middle hole 4b of the differential pressure valve member 4 and the ink guide core 5 as shown in FIG. The ink valve forming groove 4 a generates a capillary force with respect to the ink 1, and the ink 1 is interposed through the ink guide core 5 to form an ink valve that is a differential pressure valve. In order to obtain the ability to support the ink valve by the ink 1 interposed in the ink valve forming groove 4a, the ink valve forming groove 4a has a square columnar shape with a minimum width of 0.05 mm and a maximum width of 0.15 mm. . The ink valve forming groove 4a needs to have a certain opening width in order to achieve both the support of the ink valve and the ensuring of air permeability due to the difference between the internal and external air pressures. The maximum width is a surface tension of 35.0 mN / m. It is necessary to set it as 0.021 mm-0.52 mm with respect to this ink. More preferably, if the thickness is 0.03 mm to 0.20 mm, it is easy to mold and the contact area between the inner hole 4b of the differential pressure valve member 4 and the ink guide core 5 can be secured as much as possible. The variation is reduced, which is preferable. Further, the length of the ink valve forming groove 4a in the longitudinal direction is 10.0 mm, and when the decompression force and pressure increase of the air in the ink tank 2 are about ₁ mmH ₂ O to ₅ mmH ₂ O, Due to the pressure difference between the changed air pressure in the ink tank 2 and the air pressure in the original ink tank 2, the ink 1 interposed in the ink valve forming groove 4a can be displaced. . The length of the ink valve forming groove 4a in the longitudinal direction is determined based on the cross-sectional area of the ink valve forming groove 4a in consideration of the ease of pushing the ink 1 from the ink valve forming groove 4a and the air flow after the ink 1 is pushed. Although it may be 0.2 mm to 20.0 mm with respect to 0.0075 mm ² , the volume of the ink tank 2 is secured so that the capacity of the ink 1 can be increased, and the ink guide core 5 is dropped due to dropping or the like. Considering the strength, it is preferable that the thickness is 1.0 mm to 12.0 mm. Further, in this example, the pressure reduction force or pressure increase in the ink tank 2 for pushing the ink 1 is gripped by hand during writing, and the ink tank 2 is warmed by the temperature of the hand, and the ink tank 2 is heated. pressure 20 mm H ₂ O following when the air pressure was increased, for performing writing which does not cause handwriting shade has been set in consideration of decompression limit 7mmH ₂ O~15mmH ₂ O of the air in the ink tank 2 In particular, the pressure at which the ink 1 can be pushed through the ink valve forming groove 4a is not limited, and is appropriately set according to the specifications of various writing instruments.
As described above, the ink 1 that has permeated from the ink tank 2 through the ink guide core 5 penetrates the ink valve formation groove 4a by capillary force to form an ink valve, and the temperature rises due to hand gripping, The ink 1 is instantaneously pushed away from the ink valve formation groove 4a due to the slight pressure difference due to the slight pressure difference of the air generated in the ink tank 2 according to the discharge, the ink valve is opened, and the necessary air When the air is taken in from the outside or unnecessary air is discharged to the outside, the ink 1 that has permeated from the ink guide core 5 again penetrates the ink valve forming groove 4a instantaneously due to the capillary force, and the ink valve is blocked. It is made to be.

  Behind the tail plug 6, a plug body 8 in which an ink repellent filter 8 a that does not allow ink 1 to pass but allows air to pass is incorporated by insert molding is press-fitted and arranged. In this plug body 8, the ink 1 moved when the ink valve formed in the ink valve forming groove 4 a opens and closes according to the pressure change in the ink tank 2 accidentally flows out of the ink tank 2. It is intended to prevent this. This ink repellent filter 8a is a polytetrafluoroethylene formed with a three-dimensional network structure having a pore diameter of 1.0 μm and subjected to an ink repellent treatment with a fluorine-based additive. The plug 8 is an effective part in the event that the ink 1 should flow out, but since it is always installed, the ink valve formed in the ink valve formation groove 4a is opened and closed in the ink repellent filter 8a. When doing so, it is required that air can enter and exit. Therefore, the ink repellent filter 8a has a pore diameter of 0.2 μm to 3.0 μm and a thickness of about 0.1 mm to 0.5 mm, taking into consideration the time-permeation of the ink 1 and the performance of air in and out. Preferably there is. Further, in this example, as a fixing method of the ink repellent filter 8a, the plug body 8 is formed as a single part by insert molding and is press-fitted into the tail plug 6. However, it is not always necessary to use the plug body 8 by insert molding. The filter 8a is directly attached to the tail plug 6 by adhesion, heat welding, ultrasonic welding, vibration welding, solvent welding, etc., or the ink repellent filter 8a is sandwiched or fitted between the plug body 8 and the tail plug 6. For example, it can be appropriately screwed.

Between the nib 3 and the ink 1 in the ink tank 2, a comb-like temporary ink reservoir 7 of an injection molded product made of acrylonitrile butadiene styrene copolymer is disposed. The space between the adjacent narrow comb teeth 7b connected to the temporary ink reservoir 7 is a storage section for the ink 1, and the ink 1 to the comb teeth 7b is excellent so that the ink 1 can be stored in the storage section without waste. Considering wettability, uniform and narrow formability to increase the capillary force of ink 1, and reactivity such as swelling in aqueous ink 1 with water as the main solvent as in this example, acrylonitrile butadiene Styrene copolymers are preferred.
The ink 1 storage portion formed by the comb teeth 7b of the temporary ink reservoir 7 is set with good wettability and capillary force with respect to the ink 1, and the amount of ink 1 that can be stored is 1.5 cc. Yes. However, the wettability and capillary force of the ink 1 storage portion of the temporary ink reservoir 7 are set lower than the wettability and capillary force of the ink guide core 5. This is based on the general rule that the liquid does not move from the higher capillary to the lower capillary when no external force is generated. The ink 1 is not always stored in the temporary ink reservoir 7 and the ink is not stored. When the air in the tank 2 expands, the ink 1 flowing out from the ink tank 2 is stored in the temporary ink reservoir 7 before leaking from the pen tip 3 through the ink guide core 5. Due to the setting of capillary force between the ink guide core 5 and the temporary ink reservoir 7, the temporary ink reservoir 7 becomes a small amount of ink 1 in an environmental change such as moving to an area having an elevation difference or a temperature difference. Can be accommodated before leakage from the nib 3.

As described above, the ink valve is opened by a slight pressure difference of about ₁ mmH ₂ O to ₅ mmH ₂ O of air generated in the ink tank 2 in response to a temperature rise caused by hand gripping or ink ejection. After the air is taken in or discharged, the ink 1 is instantly opened and closed by the capillary force of the ink 1. In an environmental change such as moving to an area where there is an altitude difference or a temperature difference, the pressure change of the air becomes very large. Therefore, the ink valve has the air pressure in the external environment and the air in the ink tank 2. Until the pressure becomes stable, the opening / closing operation that is actively repeated is repeated each time in accordance with a small pressure difference generated in the ink tank 2. The pressure difference generated in the ink tank 2 is as small as about ₁ mmH ₂ O to ₅ mmH ₂ O, and is instantaneous and extremely short. However, when the ink valve is closed, this slight pressure is applied to the ink tank. The ink 1 is added to the interface of the ink 1 in 2, and the ink 1 is pushed down to the pen tip 3 side, although it is a small amount. Ink 1 does not drip from the nib 3 by a single opening / closing operation of the ink valve. However, assuming that an environmental change of 0.8 atm occurs in an airplane or highland, the ink valve is 500 In the meantime, the minute amount of ink 1 pushed down toward the pen tip 3 increases, and the pressure of the air in the external environment and the pressure of the air in the ink tank 2 are increased. In the meantime, the ink 1 leaks about 0.5 to 1.0 cc. Therefore, the temporary ink reservoir 7 can prevent the ink 1 from leaking from the nib 3 because the amount of ink 1 that can be stored is 1.5 cc. Further, since the amount of ink 1 that can be stored in the temporary ink reservoir 7 is only 1.5 cc, 15% of 10 cc of ink 1 stored in the ink tank 2, including the molded resin portion, Since the volume of the temporary ink reservoir 7 is about 3.0 cc, it can be 30%. For this reason, about 70 to 75% of the entire writing instrument of this example can be accommodated in the ink 1, and not only the appearance but also the fresh writing by the ink 1 in abundant free state of 10 cc and the sustainability in the writing. Can be obtained.

4 is the same as the example shown in FIG. 1 and includes an ink valve and a differential pressure valve member 4 that forms an ink valve, a tail plug 6, and a plug body 8 that is press-fitted and arranged behind the tail plug 6. Ink 1 accommodated in the ink tank 2 is obtained by dispersing ethanol with ethanol as a main solvent and dispersing a black pigment, with a surface tension of 30.8 mN / m, 3 mPa · s (B-type viscometer No. 3 rotor, 60 rpm, 25 The oil pigment for whiteboard markers is set to a low viscosity of ° C.), and the tip of a 6 mm diameter fiber converging body in which polyethylene terephthalate fibers are converged with an adhesive as a nib 3 is bullet-shaped. It is an example. The ink tank 2 is an ink replenishing type that can be closely fitted to the detachable front shaft 9 on the pen tip 3 side by screwing and can replenish the ink 1 after the ink 1 in the ink tank 2 has been used up. It is as. The ink guide core 5 is made of the same material, the same porosity, and the same diameter as the example shown in FIG. 1, but is not connected to the pen tip 3 and does not interfere with the replenishment of the ink 1. The length of the ink ink tank 2 is close to the bottom of the pen tip 3 side.

This example has a porosity of 92% made of polyethylene terephthalate fiber as a temporary ink reservoir 7 in consideration of reactivity such as swelling and dissolution with respect to oil-based ink 1 containing ethanol as a main solvent. The ink occlusion body is used. In addition, this example is of an ink replenishment type, and the ink guide core 5 has a length up to the ink tank 2, so that the ink occlusion body can be used as a supply portion of the ink 1 to the pen tip 3 and the ink occlusion body. The axial center portion of the ink 1 is 60% to 70%, which is substantially equivalent to the ink guide core 5 at the hole projection 10a of the wall portion 10 having a hole diameter of 5 mm and a length of 20 mm, and the rear end portion 3b of the nib 3. The compressed portion 7c is formed by compressing in the vertical direction so as to have a porosity of%. Since the compression part 7c serves as the ink guide core 5 by this compression part 7c, in addition to the supply of the ink 1 to the pen tip 3, the height of the capillary force is generated in the ink storage body, and the ink storage body at normal time Ink 1 is prevented from penetrating into the non-compressed portion of the ink, and the non-compressed portion of the ink occlusion body can be made into a temporary ink reservoir 7 capable of accommodating 1.6 cc to 2.0 cc of ink 1. .
Further, the wall 10 has a medium hole projection 10a that restricts the movement of the ink 1 from the ink tank 2 to the pen tip 3 to an amount that can be sufficiently written. That is, as shown in the Darcy-Weissbach equation, by setting the hole diameter and length of the medium hole protrusion 10a, movement restriction is caused by the frictional resistance of the ink 1, and an airplane, a highland, or the like is assumed. The amount of ink 1 that is pushed down to the pen tip 3 side by the opening / closing operation of the ink valve when an environmental change of 8 atm occurs is reduced as much as possible. Thereby, in particular, in the oil-based ink 1 having a lower surface tension than the water-based ink 1, the ink leaking before the air pressure in the external environment and the air pressure in the ink tank 2 are stabilized. The amount of 1 can be reduced to 50% to 60% of the amount of ink 1 that normally leaks to about 0.4 to 1.2 cc.
The Darcy-Weissbach equation is expressed as hf = f · L · v ² / D · g (hf: friction loss head, f: friction loss coefficient, L: tube length, D: tube diameter, v: Since the diameter of the medium hole protrusion 10a is set to be equal to or less than the length of the medium hole protrusion 10a, the frictional resistance that causes the movement restriction of the ink 1 is obtained.
Further, in this example, the amount of leakage of the ink 1 is reduced by providing the movement resistance of the oil-based ink 1 having a low surface tension. However, the movement resistance of the aqueous ink 1 having a relatively high surface tension is reduced. By reducing the amount of ink 1 that can be accommodated in the temporary ink reservoir 7 and making the temporary ink reservoir 7 smaller, the capacity of the ink 1 can be further increased. It is.

The compression part 7c has a porosity of 60% to 70% for obtaining the performance as the induction core of the ink 1 by compression, and is covered and connected widely so as to wrap the rear end part 3b of the nib 3. Therefore, the amount of ink 1 supplied to the pen tip 3 is set to be several times larger than the case where the ink guide core 5 and the pen tip 3 are connected, and the discharge amount of the ink 1 is relatively higher than that of other writing instruments. It can handle many whiteboard markers. In addition, the compression portion 7c has a length in the longitudinal direction that is approximately half that of the original ink occlusion body by compression, and the tip portion 10b of the medium hole protrusion 10a and the tip portion 3c of the pen tip 3 The ink 1 in the free state and the tip 3c of the nib 3 are shortened, and the capillary path along which the ink 1 moves is shortened, so that the fresh ink 1 as close to the free state as possible is obtained. Written by can be possible.
FIG. 5 shows a state where writing is performed with the nib 3 in the example of FIG. 4 facing upward. As shown in FIG. 5, when the inner hole portion 10c of the middle hole protrusion 10a is in the upward state, the compression portion 7c is saturated with the ink 1 in the downward state due to its capillary force. Due to the saturated state, only the ink tank 2 side is opened, and the same state as that of the bottomed cylindrical container is reached, and the ink 1 interposed in the inner hole portion 10c in the downward state moves to the ink tank 2 side even in the upward state. Without being held in the inner hole portion 10c. Therefore, even if writing is performed in an upward state, the supply of the ink 1 to the pen tip 3 is not interrupted for the time being, and the tip end portion 10b of the medium hole protrusion 10a and the tip end portion 3c of the pen tip 3 are prevented. And the capillary path through which the ink 1 moves is shortened, so even if writing in an upward state on a whiteboard or the like, it is sustained and close to the free state. Can be maintained.

What was shown in FIG. 6 is the comparative example of the writing instrument comprised by the prior art. The ink 1, the nib 3 and the temporary ink reservoir 7 accommodated in the ink tank 2 are an example of a whiteboard marker using the same material as the example shown in FIG. In the example of FIG. 6, about 90% of the ink 1 can be accommodated with respect to the ink tank 2 in which the inside and outside air is completely blocked by the tail plug 6 and the filling volume of 4 cc of ink 1 accommodated in the ink tank 2. A temporary ink reservoir 7 is disposed between the nib 3 and the ink tank 2.
In this comparative example, since there is no ink valve, the ink 1 in the ink tank 2 is consumed by ejection, and as the air in the ink tank 2 increases, the air expands and all the expanded air pressure Therefore, the volume of the ink 1 that can be accommodated in the temporary ink reservoir 7 is about 50 to 110% of the volume of the ink 1 that is accommodated in the ink tank 2. However, in the case of about 50% to 80%, even if the ink 1 is consumed, the volume of air does not increase so much. That is, the ink tank 2 can accommodate only a small amount of ink 1 of about 1 to 2 cc, and is limited to thin and small writing instruments. In addition, the writing instrument is used by being grasped by hand, and since the overall size is limited, even if it is assumed that a lot of ink 1 is accommodated in large quantities, the ink 1 in the case where the quantity is large The volume of the ink is about 3 to 5 cc, which is slightly larger than the so-called batting type writing instrument in which the ink occlusion body is impregnated with ink. Since the volume of the ink 1 that can be accommodated in which the portion 7 is set is about 80 to 110%, it can actually accommodate only about 20% to 30% of the ink 1 rather than about 70% or more of the entire writing instrument. Thus, in appearance and substantially, the ink 1 cannot be accommodated in a large amount.
Further, for example, the temporary ink reservoir 7 can be made as long as possible to increase the volume of ink 1 that can be stored, and the volume of ink 1 stored in the ink tank 2 can be increased somewhat. The longer the reservoir, the longer the ink supply path to the nib, and the greater the resistance of ink 1 to move, obstructing the followability of ink 1 from the nib 3, and the fresh ink as a fresh ink formula. Of course, it causes quality problems such as scumming.

As a test for confirming the effect, the writing instrument shown in FIG. 4 is used to store the amount of ink 1 in the temporary ink reservoir 7 and the length in the longitudinal direction of the inner hole portion 10b of the middle hole protrusion 10a. The samples of Examples 1 to 5 and Comparative Examples 1 to 5 were obtained by changing the thickness. About the samples of Examples 1 to 5 and Comparative Examples 1 to 5, the movement of the ink 1 due to the change in the length of the medium hole protrusion 10a caused by the change in the capacity of the ink 1 in the temporary ink reservoir 7 Written test as resistance confirmation, decompression environment test as confirmation of validity of capacity of ink 1 in temporary ink reservoir 7, visual as confirmation of whether ink amount is abundant in appearance Table 1 shows the test results for the upward writing test as confirmation of the performance test and upward writing performance. In addition, in order to investigate upward writing performance, the comparative example 5 was made into the writing instrument shown in FIG.

written examination
With a writing tester (model name: TS-4C-10, manufactured by Seiki Kogyo Laboratories), writing load: 0.98 N, writing direction: downward, writing angle: 60 °, writing speed: 70 mm per second The ink discharge amount of 50 m writing was measured, and the handwriting was visually checked for the presence or absence of scum and mottling.
Scratch: In the handwriting, there is a part that should not have ink on it, but a part that does not have ink.
Bote; A state where there is a part of the handwritten ink that needs to be inked.

Put the sample in the pressure-resistant glass case with the pressure-reducing environmental test cap removed, and reduce the pressure inside the pressure-resistant glass case until it reaches 0.80 atm of the pressure-resistant specification. It was measured. For the sample that did not leak ink at 0.80 atm, the pressure was reduced until ink leakage occurred, and the pressure at which ink leakage occurred was measured.

From the appearance of the visual test, the sample was visually observed, and 10 people were investigated whether or not it was visually recognized as a writing instrument containing a large amount of ink.

Upward writing test With a writing tester (model name: TS-4C-10, manufactured by Seiki Kogyo Laboratories), writing load: 0.98 N, writing direction: upward, writing angle; elevation angle 60 °, writing speed: 70 mm per second Under the writing conditions, the ink discharge amount of 50m writing was measured, and the presence or absence of blurring was visually confirmed on the handwriting.
Scratch: In the handwriting, there is a part that should not have ink on it, but a part that does not have ink.

As described above, according to the present invention, while preventing ink leakage from the pen tip with respect to environmental changes, an abundant amount of ink is accommodated in the ink tank, so that the writing sustainability and ink remaining as an original raw ink type can be obtained. A differential pressure valve that can be operated by a slight pressure difference between the inside and outside of the ink tank is directly connected to the ink tank so that the temporary ink reservoir can be accommodated. The ink storage volume can be obtained by making it less than 50% of the ink filling volume stored in the ink tank.

In this example, the ink tank 2 or the front shaft 9 is a main body, the ink 1 is directly stored in the main body, and a cap (not shown) that covers the pen tip when not in use is attached. As an example, the ink tank 2 and the front shaft 9 may be refilled and stored in a main body having a capless knock-out mechanism. In addition, when the ink 1 is used up, the ink tank 2 may be replaced with a cartridge exchange type by replacing the ink 1 with the ink tank 2 directly.

DESCRIPTION OF SYMBOLS 1 Ink 2 Ink tank 3 Pen tip 3a Ball-point pen tip 3b Rear end part 3c End part 4 Differential pressure valve member 4a Ink valve formation groove 4b Middle hole 5 Ink guide core 6 Tail plug 6a Top surface 7 Temporary ink reservoir 7a Middle hole 7b Comb 7c Compression part 8 Plug body 8a Ink-repellent filter 9 Front shaft 10 Wall part 10a Middle hole protrusion 10b Tip part 10c Inner hole part

Claims (4)

Temporary ink reservoir that stores ink in an ink tank in a free state, and can temporarily store the pen tip to which the ink is supplied from the ink tank, and the ink corresponding to the internal pressure increase of the ink tank. A writing instrument comprising a portion, wherein an ink valve that is operable by a pressure difference between the inside and outside of the ink tank is directly connected to the ink tank, and the ink valve is accommodated in the ink tank. Ink is supplied to the inside and outside of the ink tank to act as a communication hole, operates, the ink tank is disposed between the ink valve and the pen tip, and the ink tank is connected to the ink valve and the ink tank. An ink guide core disposed between the temporary ink reservoirs, an ink repellent filter disposed behind the ink valve, and supplying ink to the nib, With projecting forwardly from, the temporary ink reservoir, a writing instrument of the storage volume of the ink was less than 50% of the fill volume of the ink accommodated in the ink tank. The writing instrument according to claim 1, wherein the pen tip is connected to the ink tank by an ink supply pipe, and the diameter of the ink supply pipe is formed to be equal to or less than the length of the ink supply pipe. The writing instrument according to claim 1, wherein the temporary ink reservoir is an ink occlusion body. The writing instrument according to claim 3 , wherein the ink occlusion body is compressed and clamped by the pen tip and the ink supply pipe from above and below at a coaxial position of the ink occlusion body.

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