Ink reservoir and writing implement equipped with ink reservoir

Abstract

To provide an ink storage cylinder excellent in both gas barrier properties and ink visibility, and a writing instrument provided with this ink storage cylinder.SOLUTION: There are provided: an ink storage cylinder 2 which has an internal region for storing ink G for a writing instrument and is formed from a ceramic material having enough transparency to allow the ink G stored in the internal region to be seen from the outside; and a writing instrument 10 including the ink storage cylinder 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ink reservoir for storing writing ink and a writing instrument equipped with the ink reservoir. [Background technology]

[0002] Writing instruments such as ballpoint pens, fountain pens, and markers are often equipped with an ink reservoir that contains writing ink. Known ink reservoirs include metal ink reservoirs and resin ink reservoirs. Metal ink reservoirs have excellent gas barrier properties, but are not translucent, making it impossible to visually check the ink inside from the outside. In other words, they lack ink visibility. Without ink visibility, it is impossible to check the remaining ink level, leading to problems such as suddenly running out of ink and being unable to write.

[0003] On the other hand, resin ink reservoirs can provide ink visibility by using a translucent resin material, but they have poor gas barrier properties, which can lead to ink evaporation and deterioration, resulting in problems with the ink stability over time and the writing performance of writing instruments equipped with the ink reservoir.

[0004] In order to improve the gas barrier properties of such resin ink reservoir cylinders, ink reservoir cylinders have been proposed that have a multilayer resin layer structure, with at least one layer formed from an ethylene-vinyl alcohol copolymer resin (see, for example, Patent Document 1). The ink reservoir cylinder described in Patent Document 1 has improved gas barrier properties compared to conventional resin ink reservoir cylinders due to the ethylene-vinyl alcohol copolymer resin layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2002-307890 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the layer proposed in Patent Document 1 for improving the gas barrier properties is merely a resin layer, and therefore there is a natural limit to the improvement in gas barrier properties, and the gas barrier properties are not at a level sufficient for practical use.

[0007] Therefore, an object of the present invention is to solve the above problems and to provide an ink reservoir that is excellent in both gas barrier properties and ink visibility, and a writing instrument equipped with this ink reservoir. [Means for solving the problem]

[0008] An ink reservoir according to one embodiment of the present invention comprises: an interior region for containing ink for the writing instrument; The ink container is made of a ceramic material having a translucency sufficient to allow the ink contained in the internal region to be visible from the outside.

[0009] A writing instrument according to one embodiment of the present invention is a writing instrument equipped with the ink reservoir cylinder described above. [Effects of the Invention]

[0010] As described above, the present invention can provide an ink reservoir cylinder that is excellent in both gas barrier properties and ink visibility, and a writing instrument equipped with this ink reservoir cylinder. [Brief explanation of the drawings]

[0011] [Figure 1] 10 is a graph showing the results of measuring the contact angle of each sample, which is made of alumina and has different surface roughness. [Figure 2] 1 is a side cross-sectional view that schematically shows a writing instrument that includes an ink reservoir according to one embodiment of the present invention that functions as a refill for a ballpoint pen. [Figure 3]FIG. 10 is a side cross-sectional view schematically showing a writing instrument having an ink reservoir according to another embodiment of the present invention, which functions as a refill for a ballpoint pen. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, specific embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, corresponding components having the same function are given the same reference numerals.

[0013] (Outline of ink reservoir according to embodiment) Ink reservoirs containing writing ink are widely used in oil-based ballpoint pens and oil-based markers that use oil-based ink, water-based ballpoint pens and water-based markers that use water-based ink, and even fountain pens. Such ink reservoirs are often made of metal or resin. Metal ink reservoirs have excellent gas barrier properties, but are not translucent and therefore do not allow the ink to be seen. Without ink visibility, it is not possible to check the remaining ink level, which can lead to problems such as suddenly running out of ink and being unable to write.

[0014] On the other hand, resin ink reservoirs can have ink visibility by using a translucent resin material, but as mentioned above, ink reservoirs with excellent gas barrier properties have not yet been realized. If the gas barrier properties are poor, the ink will evaporate and deteriorate, causing problems with the ink's stability over time and the writing performance of a writing instrument equipped with the ink reservoir.

[0015] The inventors have found that by forming the ink reservoir from a translucent ceramic material, it is possible to realize an ink reservoir that is excellent in both gas barrier properties and ink visibility. It is clear that the use of a ceramic material can impart excellent gas barrier properties to the ink reservoir.

[0016] Furthermore, we have found that by using an appropriate ceramic material and manufacturing method, it is possible to make the ink contained in the internal region of the ink reservoir visible from the outside. In other words, we have found that it is possible to impart a level of ink visibility sufficient for practical use to the ink reservoir. For example, as described below, by using alumina (Al2O3) as the ceramic material and subjecting it to hot isostatic pressing after molding, it is possible to manufacture a ceramic ink reservoir having sufficient translucency for practical use.

[0017] The characteristics of ink reservoir tubes made of translucent ceramic material, non-translucent ceramic material, metal material, and transparent resin material are compared as shown in the table below.

[0018] [Table 1]

[0019] As shown in Table 1 above, metal materials and general ceramic materials that do not have translucency have excellent gas barrier properties but do not have ink visibility. On the other hand, transparent resin materials have ink visibility but poor gas barrier properties. Only when the ink reservoir is made of a translucent ceramic material, as in this embodiment, can both have excellent gas barrier properties and ink visibility.

[0020] The ink reservoir according to this embodiment has excellent gas barrier properties, which makes it difficult for the ink to evaporate or deteriorate, and also ensures excellent ink stability over time and writing performance for the writing instrument to which the ink reservoir is attached. In addition, the ink is visible, so the remaining ink amount can be easily checked from the outside, preventing problems such as sudden ink shortages.

[0021] As described above, in this embodiment, it is possible to provide an ink reservoir cylinder that is excellent in both gas barrier properties and ink visibility.

[0022] In particular, when the ceramic material is alumina, it is possible to provide an ink reservoir cylinder with excellent ink visibility.

[0023] In addition, because it does not use resin materials, it complies with the Sustainable Development Goals (SDGs) and can particularly contribute to environmental conservation and the prevention of global warming. Furthermore, because the ink in the internal area can be seen all around, it is easier and more reliable to know the remaining ink amount than, for example, when a gas barrier promoting film is formed on the outer surface of an ink reservoir cylinder made of transparent resin and part of it is removed to make the ink inside visible.

[0024] <Method for manufacturing the ink reservoir cylinder according to this embodiment> Next, a method for manufacturing the ink reservoir according to this embodiment will be described. The method for manufacturing the ink reservoir according to this embodiment includes the following steps. Step 1: A step of mixing a fine powder of ceramic raw material (for example, alumina (Al2O3) fine powder) with an organic binder to obtain a compound. Step 2: A step of forming a cylindrical molded body from the obtained compound using an extruder. Step 3: A step of sintering the formed compact. Step 4: A step of subjecting the obtained sintered body to a hot isostatic pressing (HIP) treatment to obtain a light-transmitting ink reservoir.

[0025] Hot isostatic pressing (HIP) can be performed, for example, at 1400°C and 1000 atmospheres in an argon atmosphere. Applying isostatic pressure to a sintered body using gas as a pressure medium reduces porosity and increases density. Sintered bodies lack translucency due to scattering from pores and precipitates, scattering from grain boundary phases, and scattering from grain boundary domains. However, applying isostatic pressure in a high-temperature environment reduces scattering factors from pores and grain boundaries, making the body translucent.

[0026] By the above-described hot isostatic pressing (HIP) treatment, it is possible to obtain a ceramic ink reservoir cylinder having a translucency sufficient to allow the ink contained in the internal region to be visually recognized from the outside.

[0027] In this embodiment, the ink reservoir is formed by extrusion molding, but the method is not limited to this and it can also be formed by a conventionally known molding method such as injection molding or press molding. In the present embodiment, the ink reservoir cylinder is manufactured by hot isostatic pressing (HIP), but the method is not limited to this. For example, the ink reservoir cylinder can be manufactured by any known manufacturing method, including a method using microwave plasma sintering, a method of performing secondary sintering at a higher temperature after primary sintering, and the like.

[0028] Although alumina is used as the ceramic material in this embodiment, the present invention is not limited to this. Any known translucent ceramic material, such as PLZT (lead, lanthanum, zirconium, and titanium oxide), can be used. Among these, alumina is preferred in view of the ease of material availability and the balance between translucency, strength, and hardness.

[0029] The crystal grain size of the ceramic constituting the ink reservoir cylinder is preferably 0.1 μm to 30 μm, more preferably 0.2 μm to 10 μm, even more preferably 0.3 μm to 5 μm, and particularly preferably 0.3 μm to 1 μm. If the crystal grain size of the ceramic falls within the above range, it is easy to achieve a balance between translucency, strength, and hardness, and, as will be described later, it is easy to adjust the surface roughness to an appropriate level.

[0030] The grain size of ceramics can be determined by the planimetric method using an SEM image. Specifically, a circle of known area is drawn on the SEM image, and the number of grains within the circle (Nc) and the number of grains on the circumference of the circle (Ni) are counted to determine the total number of grains (Nc After making the number of ( +Ni) be 250 ± 50, the crystal particle diameter can be obtained using the following formula (A). It can be obtained.

[0031] Crystal particle diameter = 2 / {π × (Nc + (1 / 2) × Ni) / (A / M2)}0.5 ·· Formula (A)

[0032] In the above formula (A), Nc is the number of crystal particles inside the circle, Ni is the number of crystal particles on the circumference of the circle, A is the area of the circle, and M is the magnification of scanning electron microscope observation (for example, 5,000 times to 10,00 0 times). In addition, when the number of crystal particles (Nc + Ni) in one SEM observation image is less than 200 pieces, (Nc + Ni) can be made 250 ± 50 using a plurality of SEM observation images. That's fine.

[0033] (Visibility of ink) Between the ink accommodated in the internal area and the inner surface of the internal area, it is generally preferable to have a contact angle of 20 degrees or more or 30 degrees or more (see "θ" in FIGS. 2 and 3). Even in the case of having a contact angle within such a range, when the contact angle is relatively small, even if the ink is consumed and the amount of ink decreases, the ink may adhere to the inner surface of the internal area, making it difficult to visually recognize the liquid level of the ink from the outside. That is, when following the ink, the ink may adhere to and remain on the inner surface of the ink storage cylinder, and there may be a problem with the visibility of the ink.

[0034] If there is a problem with the visibility of the ink, it is impossible to accurately confirm the remaining amount of ink, so there is a risk of problems such as sudden ink exhaustion.

[0035] Regarding the contact angle with the ink, generally, a smooth surface is said to have a contact angle of about 50 degrees. Furthermore, when having a contact angle of 60 degrees or more, it is said to be a "water repellency promoting surface" that can sufficiently suppress ink adhesion. Furthermore, if it is a water repellency promoting surface with a contact angle of 70 degrees or more, ink adhesion can be more effectively suppressed. Therefore, in order to ensure the visibility of the ink so that the remaining amount of ink can be accurately confirmed, it is preferable that there is a contact angle of 50 degrees or more between the ink and the inner surface of the ink storage area that comes into contact with this ink, more preferably a contact angle of 60 degrees or more, and even more preferably a contact angle of 70 degrees or more.

[0036] As described above, when the contact angle between the stored ink and the inner surface of the internal region in contact with this ink is 50 degrees or more, the ink can be made visible enough to accurately check the remaining amount of ink. Furthermore, when the contact angle between the stored ink and the inner surface of the internal region in contact with this ink is 60 degrees or more, the ink can be made even more visible, and when the contact angle between the stored ink and the inner surface of the internal region in contact with this ink is 70 degrees or more, the ink can be made even more visible.

[0037] (Relationship between surface roughness of the inner surface of the internal region and contact angle) It is known that the contact angle varies depending on the surface roughness of the contact surface. In order to obtain a contact angle that ensures sufficient ink visibility, the inventors fabricated ceramic samples with various surface roughnesses and measured their contact angles.

[0038] Specifically, rectangular alumina components were prototyped by extrusion molding, and the outer surfaces were surface-treated to create four samples with different surface roughness. The samples used were not translucent alumina but ordinary alumina (milky white), but it is believed that this had little effect on the relationship between surface roughness and contact angle.

[0039] To describe the four samples in more detail, Sample 1 was an extruded and sintered component that had been finish-processed using a lapping machine and had an arithmetic mean roughness Ra (JISB0601) of 0.011 μm; Sample 2 was an extruded component that had not been processed and had an arithmetic mean roughness Ra (JISB0601) of 0.035 μm; Sample 3 was an extruded component that had been medium-polished and had an arithmetic mean roughness Ra (JISB0601) of 0.298 μm; and Sample 4 was an extruded component that had been coarse-polished and had an arithmetic mean roughness Ra (JISB0601) of 0.540 μm.

[0040] Ion-exchanged water was dropped onto these four samples, and the contact angles were measured. More specifically, measurements were made using the sessile drop method (θ / 2 method) using an automatic contact angle meter DMo-602 manufactured by Kyowa Interface Science Co., Ltd. Light was shone on the droplet dropped onto the sample, an image of the droplet was captured with an imaging device, and the contact angle was calculated using image analysis. The measurement results are shown in the table below.

[0041] It is known that there is no difference in contact angle tendency (contact angle increases as the arithmetic mean roughness increases) between writing ink and ion-exchanged water, at least for water-based inks that use water as the main solvent. Also, for water-based inks that contain 90% or more water as a solvent, such as fountain pen inks (e.g., product name: INK-30-B, manufactured by Pilot Corporation), the difference in contact angle itself between writing ink and ion-exchanged water is slight.

[0042] Ink for writing instruments can contain additives such as surfactants to control the surface tension (contact angle with the ink reservoir). The ingredients of the fountain pen ink (INK-30-B) include dyes, water, pH adjusters, surfactants, preservatives, etc. The surface tension of the fountain pen ink (INK-30-B) was measured at 20°C using a surface tension meter (DY-200) manufactured by Kyowa Interface Science Co., Ltd., using a platinum plate by the vertical plate method, and was found to be 51 mN / m.

[0043] [Table 2]

[0044] The measurement results are shown in a graph in Figure 1. Figure 1 is a graph showing the results of measuring the contact angle of samples made from alumina with different surface roughness. The horizontal axis shows the surface roughness Ra [μm], and the vertical axis shows the contact angle [degrees]. Samples 1 to 4 above were plotted, and the graph was created by connecting the points with a smooth curve.

[0045] As is clear from Figure 1, the contact angle tends to increase as the surface roughness increases. In particular, when the surface roughness Ra [μm] is 0.1 μm or less, the degree of increase in contact angle with increasing surface roughness (the slope of the graph) is large, and when the surface roughness Ra [μm] is greater than 0.1 μm, the degree of increase in contact angle with increasing surface roughness (the slope of the graph) tends to decrease.

[0046] From the graph, it can be seen that if the inner surface roughness Ra [μm] is 0.01 μm or more, a contact angle of more than 60 degrees will be obtained, resulting in sufficient ink visibility. If the inner surface roughness Ra [μm] is 0.03 μm or more, a contact angle of more than 65 degrees will be obtained, resulting in better ink visibility. If the inner surface roughness Ra [μm] is 0.05 μm or more, a contact angle of more than 70 degrees will be obtained, resulting in even better ink visibility. The inner surface roughness Ra is measured using a stylus surface roughness meter (product name: Surfcorder SE-3400) manufactured by Kosaka Laboratory Co., Ltd. under the measurement conditions of JIS B 061-2001.

[0047] (Balance between ink visibility and ink readability) As mentioned above, increasing the surface roughness of the inner surface increases the contact angle, which is advantageous for the visibility (wettability) of the ink, but on the other hand, increasing the surface roughness may decrease transparency, i.e., increasing the surface roughness increases the scattering of light on the surface, which may reduce the visibility of the ink.

[0048] The relationship between surface roughness and transparency has been investigated, for example, in the technical paper "The influence of the surface properties of transparent acrylic resin on the visual texture" in the Journal of the Japan Society of Color Materials 92[5]131-1352019. The relationship between the measured surface roughness and transmittance of acrylic resin is shown in Fig. 6. According to Fig. 6, if the arithmetic mean height Sa (ISO 25178) is 1 μm or less, the total light transmittance is thought to exceed 80%. Also, if the arithmetic mean height Sa (ISO 25178) is 0.3 μm or less, the total light transmittance is thought to be 85% or more. Furthermore, it is stated that "if the arithmetic mean height Sa (ISO 25178) is 0.1 μm or less, the total light transmittance exceeds 90%, which is consistent with the optical properties of general acrylic resins. (See Section 3.2)"

[0049] The effect of surface roughness on transmittance is thought to be similar for translucent ceramic materials as it is for transparent acrylic resins. The arithmetic mean roughness Ra (JIS B0601) and the arithmetic mean height Sa (ISO 25178) are essentially the same indicators, and it can be assumed that reducing the arithmetic mean roughness Ra (JIS B0601) value will improve total light transmittance in ceramic materials. Therefore, although this varies depending on the material used, a arithmetic mean roughness Ra (JIS B0601) value of 1 μm or less is likely to achieve good transmittance, e.g., 30% or more, with limited impact from surface roughness and sufficient visual ink visibility. Furthermore, a arithmetic mean roughness Ra (JIS B0601) value of 0.3 μm or less is thought to further improve total light transmittance and therefore provide better ink visibility. Furthermore, it is believed that even better ink visibility (for example, transmittance of 50% or more) can be obtained by setting the value of arithmetic mean roughness Ra (JISB0601) to 0.1 μm or less.

[0050] As mentioned above, in order to achieve both ink visibility and ink recognizability, the inner surface roughness Ra [μm] is It is preferable that the particle size is in the range of 0.001 μm or more and 1 μm or less, More preferably, it is in the range of 0.005 μm or more and 1 μm or less, It is more preferable that the particle size is in the range of 0.01 μm or more and 1 μm or less, It is particularly preferable that the thickness is in the range of 0.03 μm or more and 0.3 μm or less. It is most preferable that the thickness is in the range of 0.05 μm to 0.1 μm. The range of the surface roughness Ra [μm] can be any combination of the above lower limit value and upper limit value.

[0051] When the surface roughness Ra [μm] of the inner surface of the internal region is in the range of 0.001 μm or more and 1 μm or less, an ink reservoir cylinder can be provided that has excellent ink visibility and gas barrier properties, as well as excellent ink visibility. Furthermore, when the surface roughness Ra [μm] of the inner surface is in the range of 0.005 μm or more and 1 μm or less, an ink reservoir cylinder with even better ink visibility can be provided. Furthermore, when the surface roughness Ra [μm] of the inner surface is in the range of 0.01 μm or more and 1 μm or less, an ink reservoir cylinder with even better ink visibility can be provided. Furthermore, when the surface roughness Ra [μm] of the inner surface is in the range of 0.03 μm or more and 0.3 μm or less, an ink reservoir cylinder with even better ink visibility and excellent ink visibility can be provided. Furthermore, when the surface roughness Ra [μm] of the inner surface is in the range of 0.05 μm or more and 0.1 μm or less, an ink reservoir cylinder having even better ink visibility can be provided.

[0052] (Ink stored in the ink storage tube) The ink contained in the ink reservoir will be described below. The ink contained in the ink reservoir of the present invention may be any ink normally used in writing instruments. The components used in the ink and the physical properties of the ink will be described below.

[0053] <Organic solvents> The organic solvent used in the ink used in this embodiment preferably has a boiling point of 160°C or higher, from the viewpoint of gas barrier properties, suppressing evaporation of the organic solvent, and considering the ink's stability over time, and more preferably has a boiling point of 200°C or higher. On the other hand, if the boiling point exceeds 300°C, the drying properties of the written marks are likely to be affected. For this reason, it is preferable that the boiling point be 300°C or lower.

[0054] Specifically, organic solvents used in aqueous inks include glycerin (290°C), diethylene glycol (245°C), triethylene glycol (276°C), dipropylene glycol (225°C), propylene glycol (188°C), and ethylene glycol (198°C). Examples of organic solvents for oil-based inks include benzyl alcohol (205°C), ethylene glycol monophenyl ether (245°C), and propylene glycol-n-butyl ether (170°C).

[0055] <Ink viscosity> The ink viscosity of the ink used in this embodiment at 20°C when stationary is preferably 30,000 mPa·s or less. If the viscosity exceeds 30,000 mPa·s, it is likely to affect ink tracking and therefore the visibility of the ink in the ink reservoir according to this embodiment. Therefore, in order to improve the visibility of the ink, the ink viscosity is more preferably 10,000 mPa·s or less, even more preferably 5,000 mPa·s or less, particularly preferably 4,000 mPa·s or less, and even more preferably 3,000 mPa·s or less. The ink viscosity at rest is measured under the following conditions. For oil-based ink, 20°C, shear rate 5 seconds -1 Measure the ink viscosity. For water-based ink, 20°C, shear rate 1.92 sec -1 Measure the ink viscosity.

[0056] As described above, when the viscosity of the ink contained in the internal region at 20°C when stationary is 30,000 mPa·s or less, excellent ink visibility can be obtained in the ink reservoir.

[0057] <Ink surface tension> The surface tension of the ink used in this embodiment at 20°C is preferably 20 mN / m or more. If the surface tension of the ink is equal to or greater than the above-mentioned range, the visibility of the ink in the ink reservoir according to this embodiment can be improved. In order to improve the above-mentioned effects as well as to maintain good ink dischargeability from the pen tip and obtain good handwriting, the surface tension of the ink is more preferably 25 to 65 mN / m, and even more preferably 30 to 60 mN / m.

[0058] As described above, when the ink surface tension at 20° C. of the stored ink is 20 mN / m or more, excellent ink visibility can be obtained in the ink storage cylinder. The surface tension of the ink is determined by measuring in an environment of 20° C. using a surface tension measuring instrument (DY-200) manufactured by Kyowa Interface Science Co., Ltd., by the vertical plate method using a platinum plate.

[0059] (ink follower) It is preferable that the rear end of the ink contained in the internal region of the ink reservoir be filled with an ink follower that follows the consumption of the ink (see "F" in Figure 3). This is because it improves ink followability and visibility in an ink reservoir made of ceramic material. Furthermore, it also has the effect of a liquid stopper, which further suppresses solvent evaporation from the perspective of gas barrier properties and tends to improve the ink's stability over time.

[0060] Either liquid or solid ink followers can be used, and liquid ink backflow preventers preferably contain a non-volatile medium such as polybutene or silicone oil, and if desired, silica, aluminum silicate, etc. can also be added to the medium.

[0061] As described above, when the rear end of the stored ink is filled with an ink follower that follows the consumption of the ink, the ink followability is improved and better ink visibility can be obtained.

[0062] (Writing implement with ink reservoir) Next, a writing instrument equipped with an ink reservoir will be described using a ballpoint pen as an example, with reference to Figures 2 and 3. Figure 2 is a side cross-sectional view that schematically shows a writing instrument equipped with an ink reservoir according to one embodiment of the present invention that functions as a ballpoint pen refill. Figure 3 is a side cross-sectional view that schematically shows a writing instrument equipped with an ink reservoir according to another embodiment of the present invention that functions as a ballpoint pen refill.

[0063] In the writing instrument (ballpoint pen) 10 shown in Figure 2, a ballpoint pen tip 4 is attached directly to the tip side of an ink reservoir 2 (translucent ceramics) that contains ink G1 in its internal region. In the writing instrument (ballpoint pen) 10 shown in Figure 3, the ballpoint pen tip 4 is attached via a tip holder 6 to the tip side of an ink reservoir 2 that contains ink G2 in its internal region. In the writing instrument (ballpoint pen) 10 shown in Figure 3, the rear end of the contained ink G is filled with an ink follower F (containing polybutene) that follows the consumption of the ink.

[0064] The ink viscosity of Ink G1 was measured using a TA Instruments AR-G2 (stainless steel 40 mm 2° rotor) at a shear rate of 5 sec at a temperature of 20°C. -1 When the ink viscosity was measured under static conditions, it was 20,000 mPa·s. The ink viscosity of Ink G2 was measured at a shear rate of 1.92 sec at 20°C using a Brookfield DV-II viscometer (CPE-42 rotor). -1 When the ink viscosity was measured under static conditions, it was 1600 mPa·s.

[0065] The surface tension of Ink G2 was measured in a 20°C environment using a surface tension measuring instrument (DY-200) manufactured by Kyowa Interface Science Co., Ltd., by the vertical plate method using a platinum plate, and was found to be 28 mN / m. Ink G1 ingredients: Contains dye, benzyl alcohol (205°C), ethylene glycol monophenyl ether (245°C), butyral resin, amine, and surfactant. Ink G2 ingredients: Pigment, glycerin (290°C), water, amine, surfactant, preservative, xanthan gum.

[0066] In either case, it is possible to provide an ink reservoir 2 and a writing instrument (ballpoint pen) 10 that are excellent in both gas barrier properties and ink visibility.

[0067] The ink reservoir according to this embodiment is not limited to being attached to a ballpoint pen, but can also be attached to a marker, a fountain pen, etc. Any known oil-based ink or water-based ink can be used as the ink contained in the internal region.

[0068] As described above, the first embodiment of the present invention is an interior region for containing ink for the writing instrument; The ink reservoir is made of a ceramic material that is translucent enough to allow the ink contained in the internal region to be seen from the outside.

[0069] A second embodiment of the present invention is the first embodiment, The ink reservoir cylinder has an inner surface in the internal region with an arithmetic surface roughness Ra in the range of 0.001 μm to 1 μm.

[0070] A third embodiment of the present invention is the first or second embodiment, The ink reservoir has a contact angle of 50 degrees or more between the ink contained therein and the inner surface of the internal region that comes into contact with the ink.

[0071] A fourth embodiment of the present invention is any one of the first to third embodiments, The ceramic material of the ink reservoir is alumina.

[0072] A fifth embodiment of the present invention is any one of the first to fourth embodiments, This ink storage cylinder has a surface tension of 20 mN / m or more at 20°C.

[0073] A sixth embodiment of the present invention is any one of the first to fifth embodiments, This ink reservoir has a viscosity of 30,000 mPa·s or less when the ink is stationary at 20°C.

[0074] A seventh embodiment of the present invention is any one of the first to sixth embodiments, This is an ink storage tube in which the rear end of the stored ink is filled with an ink follower that follows the consumption of the ink.

[0075] An eighth embodiment of the present invention is A writing instrument equipped with an ink reservoir according to any one of the first to seventh embodiments.

[0076] Although an embodiment of the present invention has been described, the disclosed contents may vary in the details of the configuration, and changes in the combination and order of elements in the embodiment may be realized without departing from the scope and spirit of the claimed invention. [Explanation of symbols]

[0077] 2 Ink reservoir 10 Writing instruments F Ink follower G1, G2 ink

Claims

1. an interior region for containing ink for the writing instrument; The ink cartridge is formed from a ceramic material that does not contain a resin material and has a translucency that allows the ink contained in the internal region to be visually recognized from the outside, The ink reservoir cylinder is characterized in that the crystal grain size of the ceramic material is 0.1 μm or more and 30 μm or less.

2. 2. The ink reservoir according to claim 1, wherein the arithmetic surface roughness Ra of the inner surface of the inner region is in the range of 0.001 μm to 1 μm.

3. 2. The ink reservoir according to claim 1, wherein the contact angle between the ink contained therein and the inner surface of the internal region that comes into contact with the ink is 50 degrees or more.

4. 2. The ink reservoir according to claim 1, wherein the ceramic material is alumina.

5. 3. The ink reservoir according to claim 2, wherein the ink contained therein has a surface tension of 20 mN / m or more at 20[deg.] C.

6. 3. The ink reservoir according to claim 2, wherein the ink contained therein has a viscosity of 30,000 mPa·s or less at 20° C. when stationary.

7. 3. The ink reservoir according to claim 2, wherein an ink follower is filled at the rear end of the stored ink, which follows the consumption of the ink.

8. A writing implement comprising the ink reservoir according to any one of claims 1 to 7.

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