Ink refill

Abstract

To provide an ink refill provided with a ball-point pen tip which suppresses deterioration of writing feeling and has less influence on the inner circumference of a crimped portion.SOLUTION: There is provided an ink refill including a first tapered surface at the tip of the holder that accommodates the writing ball, a connecting surface with an angle of greater than 180° measured outside the first tapered surface, and a ball-point pen tip including a first shoulder portion that is a boundary between the first tapered surface and the connecting surface and a second tapered surface with an angle of less than 180° measured outside the connecting surface and a crimped portion where the tip of the second tapered surface is crimped inward, and an ink storage tube in which ink is stored. A relationship of (A×B×108) / (C×D×E5)<8 is established in Volume A (mm3) of the annular portion outside the imaginary tangent line between the first shoulder portion and the writing ball, area B (mm2) of the gap between the writing ball and the crimped portion when viewed from the tip, ink surface tension C (mN / m), longitudinal elastic modulus D (GPa) of the holder and diameter E (mm) of the writing ball.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an ink refill for a ballpoint pen.

Background Art

[0002] As a ballpoint pen tip used as a writing tip of a ballpoint pen, there is one formed by cutting a metal cylindrical material. In such a ballpoint pen tip, after inserting a writing ball into a ball house formed inside the tip, it has a caulking portion in which the tip edge is caulked by being pressed inward to hold it.

[0003] On the other hand, when holding the writing tip downward, a phenomenon called "direct current" may occur in which ink drips due to gravity and leaks from the writing tip. In particular, in a ballpoint pen having such a caulking portion, when the writing angle with respect to the writing surface is shallow, the shoulder of the caulking portion may come into contact with the paper surface, and the inner circumference of the caulking portion may be deformed. Due to this deformation, if a gap is formed between the ball and the writing tip, direct current is likely to occur while holding the writing tip downward. There are also other problems such as deterioration of the quality of the drawn line.

[0004] Therefore, as shown in Patent Document 1, a ballpoint pen tip that can prevent direct current caused by deformation of the inner circumference of the caulking portion by preventing the shoulder of the caulking portion from contacting the paper surface during writing and an ink refill using the same are disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the invention described in Patent Document 1, when the writing angle with respect to the writing surface is small, the first shoulder portion may come into contact with the writing surface and the writing feel may deteriorate. Therefore, an embodiment of the present application aims to provide a ball pen tip and an ink refill that suppress a decrease in the writing feel and have little influence on the inner circumference of the caulked portion.

Means for Solving the Problems

[0007] (1) First Embodiment In view of the above problems, the ink refill of the first embodiment of the present application a holder, a first tapered surface in which the outer circumference of the tip of the holder is formed to be tapered, a surface formed on the tip side of the first tapered surface, and a connecting surface in which an angle measured outside the first tapered surface in a virtual cross section including the axis of the holder is greater than 180°, a first shoulder portion that is a boundary between the first tapered surface and the connecting surface, a tapered surface that is tapered and formed on the tip side of the connecting surface, and a second tapered surface in which an angle measured outside the connecting surface in the virtual cross section is less than 180°, a ball house formed as an internal space of the first tapered surface, the connecting surface, and the second tapered surface, a back hole formed as an internal space reaching from the rear end of the holder to the vicinity of the ball house, an ink hole that is a hole having a circular cross section penetrating between the ball house and the back hole, channel grooves that are a plurality of grooves equally arranged around the ink hole so as to connect the bottom surface of the ball house and the ink hole, a writing ball housed in the ball house, a ball seat formed by transferring a part of the curved surface of the writing ball on the bottom surface of the ball house, a caulked portion in which the tip portion of the second tapered surface is caulked inward, a second shoulder portion that is a boundary between the second tapered surface and the caulked portion, and a ball pen tip, and An ink refill having an ink storage tube filled with ink and having the rear end of the ballpoint pen tip attached to the front end, in a state where the writing ball is in contact with the ball seat, the volume A (mm 3 ) of an annular portion of the holder that is outside the virtual tangent line between the first shoulder portion and the writing ball in the virtual cross section, the area B (mm 2 ) of the gap between the writing ball and the caulking portion in a front view, the surface tension C (mN / m) of the ink, the longitudinal elastic modulus (Young's modulus) D (GPa) of the holder, and between the diameter E (mm) of the writing ball, (A × B × 10 8 ) / (C × D × E 5 ) < 8 is characterized in that the relationship holds.

[0008] (2) Second Embodiment In view of the above problems, the ink refill of the second embodiment of the present application, in addition to the configuration of the first embodiment, in a state where the writing ball is in contact with the ball seat, the second shoulder portion is located outside the virtual tangent line between the first shoulder portion and the writing ball in the virtual cross section, and in a state where the writing ball is in contact with the inner surface of the caulking portion, the second shoulder portion is located inside the virtual tangent line between the first shoulder portion and the writing ball in the virtual cross section.

[0009] (3) Third Embodiment In view of the above problems, the ink refill of the third embodiment of the present application, in addition to the configuration of the first embodiment or the second embodiment, the ink contains at least a colorant, water, and polyglycerin having a polymerization degree of 2 or more and 6 or less as a main skeleton, and 65 mol or more and less than 120 mol of alkylene oxide is added, and contains 0.1 mass% or more and less than 30 mass% of an alkylene oxide-added glycerin ester ester-bonded to a carboxylic acid-containing substance, The ballpoint pen tip further includes a spring that is housed inside the back hole and is formed as a pressing rod whose tip presses the writing ball toward the tip.

Advantages of the Invention

[0010] According to the ink refill of the present invention, even when the shoulder of the caulked portion contacts the paper surface during writing, it is possible to prevent direct current caused by deformation of the inner circumference of the caulked portion and improve the writing feel.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0012] The ink refill 10 according to the embodiment of the present invention is composed of a ballpoint pen tip 20, a joint 14, and an ink storage tube 11, as shown in the partial cross-sectional front view of FIG. 1. The ink storage tube 11 is a tube made of polypropylene, and an aqueous ink 12 having a viscosity of 100 to 3,000 mPa·sec at a shear rate of 3.84 sec at 25°C is filled inside. -1 is filled.

[0013] Figure 2 is a partial front sectional view of the ball pen tip 20. Further, Figure 3 is an enlarged front sectional view of the tip portion of the ball pen tip in Figure 2, and is shown as a virtual cross section including the axis 40. However, the spring 36 is omitted in Figure 3. The ball pen tip is composed of a holder 21 formed by cutting a cylindrical material made of stainless steel, a writing ball 35 housed at the tip of the holder 21, and a spring 36 housed inside the holder 21. The tip portion of the holder 21 is cut to be tapered and approximately conical to form a first tapered surface 22, and further has a connecting surface 23 with a reduced diameter inwardly on the tip side thereof, and a second tapered surface 24 protruding toward the tip side so as to further reduce the diameter therefrom.

[0014] The holder 21 is the main body portion of the ball pen tip 20 excluding the writing ball 35, and is formed, for example, by cutting a cylindrical material made of a metal such as stainless steel as in this embodiment. Alternatively, depending on the application, it may be formed by plastic deformation processing and cutting processing of a pipe material. The portion where the tip side of this holder 21 is cut to be tapered is called the first tapered surface 22. The "tip" here refers to the writing tip side of the ball pen tip 20, and the opposite side is the "rear end". The rear end portion of the holder 21 is formed as an inserted portion 28 with a reduced outer diameter, and this portion is inserted into the tip side of the joint 14 as shown in Figure 1.

[0015] The connecting surface 23 is a surface that reduces the diameter at the tip side of the first tapered surface 22, and is a surface that connects the first tapered surface 22 and the second tapered surface 24. Here, the angle formed by the first tapered surface 22 and the connecting surface 23 is greater than 180° when measured outside in a virtual cross-section including the axis 40 of the holder 21. That is, in the ballpoint pen tip 20 according to the present embodiment, it is assumed that there is a cross-section including the axis 40 of the holder 21 (this is referred to as a "virtual cross-section". FIG. 3 shows this virtual cross-section.). And when measuring the angle formed by the line segment derived from the first tapered surface 22 and the line segment derived from the connecting surface 23 in the virtual cross-section, if the angle in the solid part of the holder is the "inner side", the angle on the other "outer side" (that is, the angle that is not the solid part of the holder and is the angle α shown in FIG. 3) is greater than 180°. Here, the boundary between the first tapered surface 22 and the connecting surface 23, that is, the portion forming the vertex of the above "angle α" is the first shoulder 26.

[0016] The second tapered surface 24 is a tapered surface that is inclined so as to protrude from the connecting surface 23 such that the tip side of the connecting surface 23 further tapers. Here, the angle formed by the connecting surface 23 and the second tapered surface 24 is less than 180° when measured in the "outer side" in the same virtual cross-section as above (that is, the angle β shown in FIG. 3). Note that this angle β is an angle less than 180°, and is an angle such that the second tapered surface 24 tapers. In other words, this angle β is an angle less than 180°, and is an angle greater than the angle at which the second tapered surface 24 is parallel to the axis 40 of the holder 21.

[0017] Furthermore, the tip of the writing ball 35 held inside the first tapered surface 22, the connecting surface 23, and the second tapered surface 24 is exposed from the tip edge of the second tapered surface 24, and a caulked portion 25 is formed in which the mouth of the second tapered surface 24 is pressed inward and deformed with a reduced diameter. Inside the back hole 32 formed as the internal space of the holder 21, a spring 36 formed by a coil spring is inserted. The tip of the spring 36 is formed as a pressing rod 37 that extends straight toward the tip.

[0018] The ball house 29 is a space formed from the tip side as a portion that contacts the inner circumference of the portion where the first tapered surface 22, the connecting surface 23, and the second tapered surface 24 are located, and the writing ball 35 is inserted therein. When the holder 21 is formed of a cylindrical material as in the present embodiment, the ball house 29 is formed by cutting from the tip. However, when the holder 21 is formed of a pipe material, the internal space up to the portion pressed and deformed by punching from the outer circumference is used as it is for the ball house 29, or it is formed by cutting to slightly widen the inner diameter. The bottom surface 30 of the ball house 29 has a funnel-like shape.

[0019] As shown in FIG. 1, the back hole 32 is a central hole that reaches the vicinity (see FIG. 3) that does not reach the ball house 29 from the rear end of the holder 21. When the holder 21 is formed of a cylindrical material as in the present embodiment, this back hole 32 is formed by cutting. However, when the holder 21 is formed of a pipe material, the internal space from the rear end to the ball house 29 becomes the back hole 32 as it is. The ink 12 accommodated in the ink storage tube 11 is guided to the ball house 29 through this.

[0020] The ball house 29 and the back hole 32 are connected by an ink hole 33 which is a hole having a circular cross-section with a smaller diameter than the back hole 32. A plurality (four in the present embodiment) of channel grooves 34, which are axial grooves, are equally arranged around the ink hole 33. When the holder 21 is formed of a cylindrical material as in the present embodiment, the channel grooves 34 are formed by cutting with a channel tool from the bottom surface 30 of the ball house 29. When the holder 21 is formed of a pipe material, the gap between the portions pressed and deformed by the punching during the formation of the ball house 29 described above is used as the channel grooves 34.

[0021] The ink 12 guided to the tip of the back hole 32 will reach the ball house 29 from the ink hole 33 via this channel groove 34. That is, the channel groove 34 connects the ball house 29 whose bottom surface 30 is blocked by the writing ball 35 and the ink hole 33. Note that when the ink 12 to be used has a relatively high viscosity and is less likely to cause direct flow, it is desirable to penetrate to the back hole 32 from the perspective of the flow of the ink 12. On the other hand, when the ink 12 to be used has a relatively low viscosity and is likely to cause direct flow, it is desirable not to penetrate to the back hole 32 but to stop it in the middle of the ink hole 33 as shown in FIG. 3.

[0022] Here, the writing ball 35 is a spherical body made of metal such as super-hard stainless steel and is inserted into the ball house 29. The ink that reaches the ball house 29 will adhere to the surface of the writing ball 35 and be transferred to the writing surface.

[0023] The writing ball 35 inserted into the ball house 29 is pressed backward by so-called "tapping processing", and the concave curved surface formed by transferring a part of the curved surface of the writing ball 35 to the bottom surface 30 of the ball house 29 is the ball seat 31.

[0024] Furthermore, after the writing ball 35 is inserted into the ball house 29 and undergoes the above-mentioned tapping processing, the small end of the second tapered surface 24 is caulked inward, and the portion where the inner diameter is reduced is the caulked portion 25. This caulked portion 25 is a structure that holds the writing ball 35 and prevents it from falling. The boundary between this caulked portion 25 and the second tapered surface 24 is the second shoulder 27.

[0025] The ball pen tip 20 shown in FIG. 2 is mounted on the tip of the synthetic resin ink storage tube 11 via the joint 14 in a state where its inserted portion 28 is inserted into the joint 14, and becomes the ink refill 10 (see FIG. 1). An aqueous gel ink is injected into the ink storage tube 11 of the ink refill 10 as the ink 12, and a grease-like ink follower 13 is injected into the rear end of the ink 12 to prevent the ink 12 from leaking from the rear end.

[0026] In addition to the above structure, in the virtual cross-section, further assuming that there is a tangent line between the writing ball and the first shoulder (this is referred to as the "virtual tangent line"), (A × B × 10 8 ) / (C × D × E 5 ) < 8 the following relationship holds. Here, "A" is the volume of the annular portion outside the virtual tangent line between the first shoulder and the writing ball in the virtual cross-section (unit: mm 3 ), "B" is the area of the gap between the writing ball and the caulked portion in the front view (unit: mm 2 ), "C" is the surface tension of the ink (unit: mN / m), "D" is the longitudinal elastic modulus (Young's modulus) of the holder (unit: GPa), and "E" is the diameter of the writing ball (unit: mm).

[0027] Here, as shown in FIG. 3, in the state where the writing ball 35 is in contact with the ball seat 31, the second shoulder 27 is located outside the virtual tangent line 41 between the first shoulder 26 and the writing ball 35 in the virtual cross-section. Specifically, the volume A is the portion including this second shoulder 27, and the triangular region indicated by "A" in FIG. 3 is the volume of the annular portion obtained by rotating around the axis 40. Since this portion is outside the virtual tangent line, when the writing angle with respect to the paper surface is small, the portion near this second shoulder 27 hits the paper surface before the first shoulder 26.

[0028] Here, since the first tapered surface 22 and the connecting surface 23 before and after the first shoulder 26 are formed by cutting, the surface roughness has a relatively large value. On the other hand, since the caulked portion 25 on the tip side from the second shoulder 27 is formed by plastic deformation, it is processed smoother and closer to a mirror surface than the vicinity of the first shoulder 26. Therefore, compared with the case where the second shoulder 27 is inside the virtual tangent line, when the writing angle is small, the writing surface contacts the smooth second shoulder 27 before contacting the rough first shoulder 26, so a smoother writing feeling can be obtained.

[0029] Regarding the ratio of volume A to the volume of the writing ball 35, if it is less than 1%, due to the wear associated with writing, the second shoulder 27 will come into contact with the writing surface earlier than the first shoulder 26, and the smooth writing feeling will be quickly lost. On the other hand, if it is 15% or more, the catching feeling during writing caused by the second shoulder 27 will rather increase. Therefore, in order to obtain the effect of the present invention, namely the smooth writing feeling as described above, the ratio of volume A to the volume of the writing ball is preferably 1% to 15%.

[0030] Regarding the above-mentioned area B, if it is less than 5% of the cross-sectional area of the writing ball 35, the writing line will become thin. On the other hand, if it is 15% or more, the DC prevention effect cannot be fully exerted. Therefore, the ratio of area B to the cross-sectional area of the writing ball 35 is preferably 5% or more and less than 15%.

[0031] The holder 21 is preferably formed of a non-lead metal material. Regarding the longitudinal elastic modulus (Young's modulus) D of the holder 21 formed of this material, if it is less than 190 GPa corresponding to the plastic region of the metal material, when an impact such as dropping is applied to the writing tip, plastic deformation will occur, and elastic recovery is difficult to occur. On the other hand, if the longitudinal elastic modulus D is 210 GPa or more, it is difficult to process the metal material into the holder 21. Therefore, the longitudinal elastic modulus D of the holder 21 is preferably 190 GPa or more and less than 210 GPa.

[0032] The caulking portion 25 preferably has an arithmetic mean height Sa of the surface of 10 nm or less. The protruding dimension from the end face of the caulking portion 25 to the tip of the writing ball 35 is preferably 30% or more of the diameter of the writing ball 35. On the inner surface of the caulking portion 25, a sealing surface 25a along the writing ball 35 is formed to make the inside of the ball house airtight. The axial length C of the sealing surface 25a is preferably 5 μm or more and less than 30 μm.

[0033] Note that in FIG. 3, the pressing rod 37 of the spring 36 that biases the writing ball 35 in the tip direction is omitted. This FIG. 3 shows a state where the writing ball 35 is pressed in the rear end direction by the writing surface during writing and is in contact with the ball seat 31. On the other hand, when not writing, as shown in FIG. 4, the writing ball 35 is also pressed in the tip direction by the pressing rod 37 of the spring 36 (not shown in the figure) and is in contact with the inner surface of the caulking portion 25, that is, the sealing surface 25a. As a result, the ball house 29 is blocked from the outside and direct current is prevented. In this state, the second shoulder portion 27 is located inside the virtual tangent line 42 between the first shoulder portion 26 and the writing ball 35 in the virtual cross section including the axis 40 (see FIG. 3).

[0034] The ink 12 of the present embodiment is an ink containing at least a colorant and water, wherein the main skeleton is polyglycerin having a polymerization degree of 2 or more and 6 or less, 65 mol or more and 120 mol or less of alkylene oxide is added, and an alkylene oxide-added glycerin ester ester-bonded to a carboxylic acid-containing substance is contained in an amount of 0.1% by mass or more and less than 30% by mass of the whole ink.

[0035] The alkylene oxide-added glycerin ester used in the embodiment is contained to improve writing feel, non-bleeding property, and drying property of the drawn line without changing the ink physical properties over time even during long-term storage. The main skeleton is polyglycerin having a polymerization degree of 2 or more and 6 or less, 65 mol or more and 120 mol or less of alkylene oxide is added, and it is ester-bonded to a carboxylic acid-containing substance. This alkylene oxide-added glycerin ester is obtained by reacting polyglycerin having a polymerization degree of 2 or more and 6 or less, 65 mol or more and 120 mol or less of alkylene oxide, and a carboxylic acid-containing substance.

[0036] In an embodiment, the degree of polymerization of the polyglycerin used as the glycerin backbone is desirably 2 or more and 6 or less. If this degree of polymerization exceeds 6, the bulkiness of the whole molecule increases, improving the writing feel and the non-bleeding property of the drawn lines, but it will not dry and as a result problems such as dirty hands will occur.

[0037] In an embodiment, the alkylene oxide used includes at least one of ethylene oxide, propylene oxide, butylene oxide, etc. (each alone or in combination of two or more, the same applies hereinafter), and preferably ethylene oxide from the viewpoint of the hydrophilicity of the alkylene oxide. The number of moles of addition of this alkylene oxide is desirably 65 to 120 moles. If the number of moles of addition is less than 65 moles, the non-bleeding property decreases and the swelling degree of the paper surface is low, so a dramatic improvement in the writing feel cannot be expected. Also, when used in pigment ink, the dispersibility decreases. On the other hand, if the number of moles of addition exceeds 120 moles, the ink viscosity increases. Therefore, especially when designing a low-viscosity ink, it is necessary to reduce the content, and the desired writing feel and non-bleeding property cannot be exhibited. Also, when used in pigment ink, in order to ensure the content for achieving pigment dispersion stability, an increase in ink viscosity is inevitable, and as a result, the content has to be reduced, and the dispersion stability cannot be ensured. Furthermore, when imparting shear thinning viscosity to the ink, although there is a margin in terms of viscosity compared to low-viscosity ink, the viscosity before containing the viscosity-imparting agent becomes high, and as a result, the content of the viscosity-imparting agent has to be reduced. Especially when contained in pigment ink, the pigment will settle over time.

[0038] In an embodiment, examples of the carboxylic acid-containing substance used include at least one of fatty acids, aromatic carboxylic acids, etc. The fatty acid used may be linear or branched, or saturated or unsaturated. From the viewpoint of further improving the effects of the embodiment, a fatty acid having 4 to 25 carbon atoms is preferable, and more preferably a fatty acid having 8 to 20 carbon atoms is desirable. Examples include capric acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, hydroxystearic acid, oleic acid, etc. Examples of the aromatic carboxylic acid include benzoic acid, α-naphthalene carboxylic acid, β-naphthalene carboxylic acid, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, etc., and those having substituents such as alkyl, halogen, alkoxy may also be used.

[0039] When the fatty acid has less than 4 carbon atoms, the hydrophilicity in the molecule becomes relatively high, which may reduce the scribing drying property. Also, when contained in the pigment ink, the pigment adsorption ability decreases, so the pigment dispersibility may decrease. On the other hand, when the fatty acid has more than 25 carbon atoms, similar to the number of moles of added alkylene oxide, the ink viscosity increases, resulting in restrictions in ink viscosity design.

[0040] In the alkylene oxide-added glycerin ester of the embodiment, preferably, from the viewpoints of the hydrophilicity of the molecule, the pigment adsorption property in the case of pigment ink, and the ink viscosity design, when the number of moles of the carboxylic acid-containing substance is X and the degree of polymerization of glycerin is Y, X / 〔Y + 2〕, that is, the esterification degree (number of ester groups / number of hydroxyl groups) is desirably 0.30 to 0.60.

[0041] As described above, the alkylene oxide-added glycerin ester of the embodiment is obtained by reacting polyglycerin having a degree of polymerization of 2 to 6 with 65 to 120 moles of alkylene oxide and a carboxylic acid-containing substance. The main skeleton is composed of glycerin, 65 to 20 moles of alkylene oxide are added, and it is in a configuration where it is ester-bonded to the carboxylic acid-containing substance. Its HLB is desirably 16 to 20.

[0042] When this HLB is less than 16, the number of moles of added alkylene oxide is small, and the number of moles of alkyl group and aromatic addition increases, which causes a decrease in writing feel. Also, when used in pigment ink, it causes a decrease in dispersion stability. On the other hand, when the HLB exceeds 20, the number of moles of added alkylene oxide increases, resulting in restrictions in ink viscosity design due to an increase in ink viscosity, etc.

[0043] The average molecular weight of the alkylene oxide-added glycerin ester in the embodiment is desirably in the range of 3000 to 9000. If this average molecular weight is less than 3000, it will lead to a decrease in line drying performance due to insufficient hydrophobic groups, which are the components that penetrate into the paper surface. In addition, in the case of pigment ink, the pigment dispersibility will be poor. On the other hand, if the average molecular weight exceeds 9000, restrictions will occur in the ink viscosity design due to an increase in ink viscosity and the like.

[0044] The content of the alkylene oxide-added glycerin ester in the embodiment is desirably 1 to 10% by mass based on the total amount of the ink composition. If this content is less than 1% by mass, the writing feel cannot be improved. On the other hand, if it exceeds 10% by mass, in the case of Newtonian ink, the viscosity will increase and the target viscosity cannot be set. In addition, in the case of non-Newtonian ink, when setting the target viscosity, it is necessary to limit the content of the non-Newtonian imparting agent. As a result, the network structure will not be strong enough, and problems such as pigment sedimentation will occur.

[0045] As the colorant used in the embodiment, any one of inorganic and organic pigments, water-soluble dyes, or oil-soluble dyes that dissolve in water at a low concentration can be used. When using an oil-soluble dye, it is possible to improve the solubility of the dye by dissolving an organic solvent in the vehicle. Examples of inorganic pigments include titanium oxide, carbon black, and metal powder. Examples of organic pigments include azo lake, insoluble azo pigment, chelate azo pigment, phthalocyanine pigment, perylene and perinone pigment, anthraquinone pigment, quinacridone pigment, dye lake, nitro pigment, and nitroso pigment. Any of direct dyes, acid dyes, food dyes, and basic dyes can be used as the water-soluble dye.

[0046] The content of these colorants is preferably in the range of 1 to 15% by mass based on the total amount of the composition of Ink 12. If the content of this colorant exceeds 15% by mass, when stored for a long time, the pigment may aggregate or the dye may precipitate, clogging the pen tip and causing poor writing. Also, if it is less than 1% by mass, the coloring becomes weak and the hue when writing on paper becomes indistinguishable, which is not preferable.

[0047] Regarding the pH of Ink 12 of the embodiment, it is preferable to adjust the pH of the ink composition to the range of 7 to 10 (measurement temperature: 25°C, measuring instrument: pH meter manufactured by Horiba). Adjusting the pH of Ink 12 to the above range is for rust prevention when the ball pen tip uses a metal material, and to prevent aggregation of the dispersant specified for pigment dispersion and undissolution of the acid dye used as the colorant.

[0048] The viscosity of Ink 12 of the embodiment can be used in a wide viscosity range. In the case of a low-viscosity ink with a Newtonian viscosity of 1 to 10 mPa·S, effects can be seen in non-bleeding and writing feel. Regarding inks with a viscosity of about 10 to 100 mPa·s, the same effects as those of low-viscosity inks can be expected. For non-Newtonian viscous inks, when the ink viscosity at a shear rate of 3.84 s -1 is about 100 to 4000 mPa·s, a strong network structure can be constructed with a non-Newtonian property imparting agent, and physical property stability can be achieved.

[0049] The surface tension of Ink 12 is preferably set in the range of 30 to 40 mN / m (measurement temperature: 25°C, measuring instrument: surface tension measuring instrument manufactured by Kyowa Interface Science Co., Ltd.). If the surface tension of Ink 12 is below the above range (less than the minimum value of each range), the written line may easily bleed or phenomena such as direct current and bleeding may occur. If it exceeds the above preferable range, the writing feel and flow rate stability of the pen may decrease.

[0050] In the ink 12 of the embodiment, a water-soluble organic solvent can be used as a humectant for preventing the drying of the writing tip, if necessary. Derivatives such as glycerin, diglycerin, and polyglycerin can be contained in the ink for the purpose of obtaining the same effect as that of the organic solvent due to their moisturizing effect. The content of these water-soluble organic solvents is desirably in the range of 5 to 40% by mass based on the total amount of the composition of the ink 12. If the content of this water-soluble organic solvent exceeds 40% by mass, the drawn line becomes difficult to dry, which is not preferable.

[0051] Also, in the ink 12 of the embodiment, saccharides, urea derivatives, etc. can be used as a humectant for preventing the drying of the writing tip, if necessary. The humectants may be used alone or in combination of two or more.

[0052] The content of these humectants such as saccharides and urea derivatives is desirably 0.25 to 10% by mass based on the total amount of the composition of the ink. If the content of this humectant is less than 0.25% by mass, the effect as a humectant is not exhibited. On the other hand, if it exceeds 10% by mass, it will cause an increase in ink viscosity and a decrease in the drying property of the drawn line.

[0053] In addition to the above, the ink 12 of the embodiment can contain a lubricant, a preservative, a pH adjuster, a water-soluble alkali-soluble resin, a resin emulsion, a corrosion inhibitor, an antioxidant, and a thickener, if necessary, and the balance is adjusted with water (ion-exchanged water, purified water, distilled water, pure water, ultrapure water, etc.).

[0054] Examples of lubricants include fatty acid salts such as potassium linoleate, sodium ricinoleate, potassium oleate, and sodium oleate, and other nonionic, anionic, and amphoteric surfactants shown below. In the case of particularly low-viscosity inks (about 10 mPa·s), from the perspective of non-bleeding properties, the content is preferably 0.01 to 2.0% by mass, more preferably 0.05 to 1.5% by mass, and particularly desirably 0.1 to 1.2% by mass, based on the total amount of the ink composition. When the ink has non-Newtonian viscosity and is 100 to 4000 mPa·s (at a shear rate of 3.84 s -1 ), the content may not need to be restricted due to its viscosity effect.

[0055] Examples of preservatives include phenol, isopropylmethylphenol, sodium pentachlorophenol, benzoic acid, sodium benzoate, dehydroacetic acid, sodium dehydroacetate, sorbic acid, potassium sorbate, sodium 2-pyridinethiol-1-oxide, 1,2-benzisothiazol-3-one, 5-chloro-2-methyl-4-isothiazol-3-one, 2,4-thiazoline benzimidazole, paraoxybenzoic acid ester, and the like.

[0056] Examples of pH adjusters include amines or bases, such as various organic amines like aminotriethanolamine, monoethanolamine, and diethanolamine, inorganic alkalis such as hydroxides of alkali metals like sodium hydroxide, lithium hydroxide, and potassium hydroxide, and ammonia.

[0057] Water-soluble alkali-soluble resins or resin emulsions are mainly contained with the expectation of acting as viscosity modifiers and water resistance agents. For example, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyethylene, polycarbonate, polymethyl methacrylate, benzoguanamine resin, styrene-acrylonitrile copolymer, modified acrylic methyl methacrylate-styrene copolymer, alkyl acrylate copolymer, acrylonitrile-alkyl acrylate copolymer, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate-alkyl acrylate copolymer, styrene-acrylonitrile-alkyl methacrylate-alkyl acrylate copolymer, alkyl methacrylate-alkyl acrylate copolymer, acrylic acid-methacrylic acid-alkyl acrylate copolymer, vinylidene chloride-alkyl acrylate copolymer, etc. can be mentioned.

[0058] Antioxidants are mainly used to suppress the hydrolysis of the ester compounds of the embodiments or to eliminate problems caused by gas expansion in writing instruments such as ballpoint pen shafts. Specifically, at least one of sodium L-ascorbate, sodium erythorbate, polyphenols such as vinylpyrrolidone oligomer and tocopherol, catechin, flavangenol, BHT (dibutylhydroxytoluene), BHA (butylhydroxyanisole), acetylcysteine, etc. can be mentioned.

[0059] Thickening agents are roughly classified into organic thickening agents and inorganic thickening agents. As organic thickening agents, for example, acrylic synthetic polymers, natural gums, cellulose, and polysaccharides can be used. Specifically, gum arabic, tragacanth gum, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, casein xanthan gum, welan gum, succinoglycan, alcalan, dextran, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium starch glycolate, propylene glycol alginate, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether, sodium polyacrylate, carboxyvinyl polymer, polyethylene oxide, a copolymer of vinyl acetate and polyvinyl pyrrolidone, a cross-linked acrylic acid polymer, an acrylic swelling associative emulsion, a salt of a styrene-acrylic acid copolymer, etc. can be mentioned. As inorganic thickening agents, for example, clays such as smectite, bentonite, and diatomaceous earth, and fine particles such as silicon dioxide can be mentioned. The content of these thickening agents is appropriately increased or decreased according to the viscosity value of the ink.

[0060] As corrosion inhibitors, for example, tolyltriazole, benzotriazole and its derivatives, fatty acid phosphorus derivatives such as octyl phosphate and dioctyl thiophosphate, imidazole, benzimidazole and its derivatives, 2-mercaptobenzothiazole, octylmethanesulfonic acid, dicyclohexylammonium nitrite, diisopropylammonium nitrite, propargyl alcohol, dialkylthiourea, etc. can be mentioned.

Example

[0061] As an example, ink refill using two types of inks was evaluated by a DC test and a sensory test of the snagging feeling.

[0062] (1) Ink 1 Ink 1 had the following composition. Colorant (water black): 5% by mass Solvent (ethylene glycol): 20% by mass pH adjuster (triethanolamine): 0.3% by mass pH adjuster (aminomethylpropanol): 0.1% by mass Preservative (2-benzisothiazolin-3-one): 0.1% by mass Rust inhibitor (benzotriazole): 0.3% by mass Thickener (xanthan gum): 0.4% by mass Saccharide (glucose): 2% by mass Acetylene oxide-added glycerin ester (molecular weight 5043, HLB 18): 3% by mass Purified water: the balance

[0063] The viscosity of Ink 1 with the above composition, measured at a measurement temperature of 25°C using an ELD·EMD type viscometer (Tokimec) as the measuring instrument, was 1500 mPa·s at a rotation speed of 1 rpm and 230 mPa·s at a rotation speed of 50 rpm. Also, the pH of Ink 1 measured at 25°C using a pH meter (Horiba) was 8.5. Furthermore, the surface tension (C) of Ink 1 was 32 mN / m.

[0064] This Ink 1 was filled into the ink storage tube of an ink refill as shown in FIG. 1. The ballpoint pen tip attached to the tip of the ink storage tube was one in which a writing ball with a ball diameter (E) of 0.7 mm was housed in a holder made of stainless steel. The Young's modulus (D) of this holder was 200 GPa. Also, the pressing load of the spring that presses the writing ball was an average of 15 g weight (0.15 N).

[0065] As ink refills using this Ink 1, ink refills of Examples 1 to 4 and Comparative Examples 1 to 3 shown in Table 1 below were prepared.

[0066] (2) Ink 2 Ink 2 had the following composition. Colorant (carbon black): 7% by mass Solvent (ethylene glycol): 10% by mass Solvent (propylene glycol): 15% by mass pH adjuster (triethanolamine): 0.3% by mass pH adjuster (aminomethylpropanol): 0.1% by mass Preservative (2-benzisothiazolin-3-one): 0.1% by mass Rust inhibitor (benzotriazole): 0.1% by mass Urea: 1.5% by mass Acetylene oxide-added glycerin ester (molecular weight 5095, HLB 17.8): 1% by mass Purified water: the balance

[0067] The viscosity of Ink 2 with the above composition, measured at a measurement temperature of 25°C in the same manner as Ink 1, was 3.8 mPa·s at a rotational speed of 50 rpm. Also, the pH of Ink 2 measured in the same manner as Ink 1 was 8.5. Furthermore, the surface tension (C) of Ink 2 was 38 mN / m.

[0068] This Ink 2 was filled into the ink storage tube of an ink refill as shown in FIG. 1. The ballpoint pen tip attached to the tip of the ink storage tube was one in which a writing ball with a ball diameter (E) of 0.5 mm was housed in a holder made of stainless steel. The Young's modulus (D) of this holder was 193 GPa. Also, the pressing load of the spring that presses the writing ball was an average of 15 g (0.15 N).

[0069] As ink refills using this Ink 2, ink refills of Examples 5 to 10 and Comparative Examples 5 and 6 shown in Table 2 below were prepared.

[0070] (3) Test method (3-1) DC test Under an environment of a temperature of 23 ± 2°C and a relative humidity of 65 ± 10%, with the writing tip extended from the tip of the ballpoint pen shaft equipped with the ink refill of each example or comparative example, the writing tip was dropped downward from a height of 1 m onto a receiving plate having an inclination of 50° with respect to the horizontal plane. Then, a circle of about 20 to 25 cm was written freehand for 5 rounds and immediately fixed downward and left for 60 minutes. Then, the size of the ink droplet accumulated at the tip of the ballpoint pen tip was measured. The judgment criteria are as shown below. Evaluation A: No generation of ink droplets Evaluation B: The size of the ink droplets is more than 0 mm and 1 mm or less Evaluation C: The size of the ink droplets is more than 1 mm and 2 mm or less Evaluation D: The size of the ink droplets is more than 2 mm

[0071] (3-2) Snagging feeling test The subject was allowed to freely write while keeping the writing angle at approximately 45° using a ballpoint pen equipped with the ink refill of each example or comparative example. Regarding the snagging feeling at that time, sensory evaluation was performed as shown below. Evaluation A: No snagging feeling at all Evaluation B: Slight snagging feeling Evaluation C: There is a snagging feeling Evaluation D: Considerable snagging feeling

[0072] (4) Test results The evaluation results using Ink 1 are shown in Table 1 below, and the evaluation results using Ink 2 are shown in Table 2 below. In addition, "A" in each table is the volume A (see Figure 3) of the annular portion outside the virtual tangent line 41 between the first shoulder portion 26 and the writing ball 35 in the virtual cross-section including the axis 40 among the holders 21, and the unit is mm 3 is. Also, "B" in each table is the area B (see Figure 3) of the gap between the writing ball 35 and the caulking portion 25 in the front view, and the unit is mm 2 is. Also, "F" in each table is a value calculated by the following formula based on the above parameters A to E. F=(A×B×10 8 ) / (C×D×E 5 )

[0073]

Table 1

[0074]

Table 2

[0075] From Table 1 and Table 2 above, in all examples and comparative examples, the evaluation results regarding the catching feeling were highly evaluated as "A".

[0076] Here, in any of Comparative Examples 1 to 4 using Ink 1 and Comparative Examples 5 and 6 using Ink 2, the F value exceeded 8. Along with this, the evaluation of the DC test was "C" even in the best Comparative Examples 1, 4, and 6, and "D" in the other comparative examples, which were not good results.

[0077] On the other hand, in all of Examples 1 to 4 using Ink 1 and Examples 5 to 10 using Ink 2, the F value was below 8. Along with this, the evaluation of the DC test was "B" (Examples 1, 5, and 9) at worst, and "A" in the other examples, which were excellent results.

[0078] From the formula for calculating the F value described above, as the A value and B value increase, the F value increases. Along with this, as shown in Table 1 and Table 2 above, there is a tendency for the evaluation of the DC test to deteriorate. This is considered because when the thickness of the caulked portion including "A" in FIG. 3 is large, the deformation when the writing tip collides is difficult to recover, so DC is likely to occur thereafter. On the other hand, when the thickness of the caulked portion is small, the first shoulder portion 26 (see FIG. 3) is more likely to collide, so the deformation of the caulked portion is less likely to occur, and it is considered that the adverse effect on DC was small.

Industrial Applicability

[0079] The present invention can be used for ink refilling of ballpoint pens.

Explanation of Signs

[0080] 10 Ink refill 11 Ink storage tube 12 Ink 14 Joint 20 Ballpoint pen tip 21 Holder 22 First tapered surface 23 Connecting surface 24 Second tapered surface 25 Caulked portion 25a Sealing surface 26 First shoulder 27 Second shoulder 28 Inserted part 29 Ball house 30 Bottom surface 31 Ball seat 32 Back hole 33 Ink hole 34 Channel groove 35 Writing ball 36 Spring 37 Pressing rod 40 Axis 41 Virtual tangent line 42 Virtual tangent line

Claims

1. A holder and a first tapered surface having an outer periphery at a tip end of the holder that is tapered; a connecting surface formed on a tip side of the first tapered surface, the connecting surface having an angle of greater than 180° measured on the outside relative to the first tapered surface in a virtual cross section including an axis of the holder; a first shoulder portion which is a boundary between the first tapered surface and the connecting surface; a second tapered surface formed on the tip side of the connecting surface, the second tapered surface having an angle of less than 180° measured on the outside relative to the connecting surface in the imaginary cross section; a ball house formed as an internal space between the first tapered surface, the connecting surface, and the second tapered surface; a back hole formed as an internal space extending from a rear end of the holder to a vicinity of the ball house; an ink hole having a circular cross section penetrating between the ball house and the back hole; a plurality of channel grooves that are equally spaced around the ink hole so as to connect the bottom surface of the ball house and the ink hole; A writing ball housed in the ball house; a ball seat formed on a bottom surface of the ball house by transferring a part of the curved surface of the writing ball; a crimped portion in which a tip portion of the second tapered surface is crimped inward; A ballpoint pen tip including a second shoulder portion that is a boundary between the second tapered surface and the crimped portion; and The rear end of the ballpoint pen tip is attached to a front end of the ink refill, which includes an ink reservoir tube filled with ink, In a state where the writing ball is in contact with the ball seat, The volume A (mm ３ ), The area B (mm ２ ), The surface tension C of the ink (mN / m), The Young's modulus D (GPa) of the holder, and Between the diameter E (mm) of the writing ball, (A×B×10 ８ ) / (C×D×E ５ )<8 An ink refill characterized in that the following relationship holds:

2. When the writing ball is in contact with the ball seat, the second shoulder is located outside a virtual tangent line between the first shoulder and the writing ball in the virtual cross section, 2. The ink refill according to claim 1, characterized in that, when the writing ball is in contact with the inner surface of the crimped portion, the second shoulder is located inside a virtual tangent between the first shoulder and the writing ball in the virtual cross section.

3. The ink contains at least a colorant, water, and polyglycerin having a degree of polymerization of 2 or more and 6 or less as a main skeleton, and contains 0.1% by mass or more and less than 30% by mass of alkylene oxide-added glycerin ester to which 65 moles or more and 120 moles or less of alkylene oxide are added and which is ester-bonded to a carboxylic acid-containing substance, 3. The ink refill according to claim 1, wherein the ballpoint pen tip further comprises a spring housed inside the back hole and having a tip portion formed as a pressing rod for pressing the writing ball toward the tip.

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