Ballpoint pen tip

Abstract

To provide a ballpoint pen tip which can prevent a seal member from being unintentionally removed from the ballpoint pen tip, and also allows a user who wants to remove the seal member from the ballpoint pen tip to do so without feeling bothered.SOLUTION: The gist of the present invention is a ballpoint pen tip in which a mirror-like portion 16 having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less is formed on the outer wall surface of a ball holder 8, a part of the writing ball protrudes from the front end opening and is prevented from slipping out of the front end opening by a crimped portion and is rotatably arranged within the ball holder, and a resin sealing member 17 which is a hot melt agent is arranged at the front end of the ballpoint pen tip so as to cover part of the front end of the ballpoint pen tip and include at least part of the mirror-like portion.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a ballpoint pen tip. [Background technology]

[0002] Ballpoint pen tips whose front end is covered with a resin sealing member have been disclosed. Ballpoint pen tips are primarily composed of a cylindrical ball holder and a writing ball. A portion of the writing ball protrudes from the front opening of the ball holder, and the gap between the writing ball and the edge forming the front opening of the ball holder functions as an outlet for ballpoint pen ink. Patent Document 1, for example, discloses a sealing member made of a mixture of thermoplastic resin, adhesive resin, and wax as an invention for temporarily sealing the gap to prevent ballpoint pen ink leakage from a ballpoint pen tip, a ballpoint pen refill using the ballpoint pen tip, or a ballpoint pen using the ballpoint pen refill during manufacturing, transportation, display, etc. Such sealing members are called hot-melt agents, which become liquid when heated and solid when cooled below room temperature, and are often used as sealing members for ballpoint pen tips. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-14552 Summary of the Invention [Problem to be solved by the invention]

[0004] The sealing member must cover the ballpoint pen tip with sufficient attachment strength (difficulty in removal) when the ballpoint pen is in an unused state, such as during the aforementioned manufacturing, transportation, and display, when the ballpoint pen tip begins to eject ballpoint pen ink. On the other hand, when the ballpoint pen begins to be used, the sealing member must be able to be removed without the user applying excessive force or using a special method. Therefore, the higher the attachment strength, the more preferable it is.

[0005] To provide a ballpoint pen tip that can prevent a seal member from being unintentionally removed from the ballpoint pen tip, and also allows a user who wants to remove the seal member from the ballpoint pen tip to do so without feeling bothered. [Means for solving the problem]

[0006] The present invention provides a ballpoint pen tip comprising at least a ball holder and a writing ball, wherein the ball holder is formed with at least a front end opening, a crimped portion that forms the front end opening, a tapered portion that is located axially rearward of the crimped portion and has an outer diameter that narrows toward the front end opening, and an ink flow hole inside; the tapered portion that is the outer wall surface of the ball holder is formed with a mirror-like portion having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less; the writing ball protrudes partially from the front end opening and is prevented from slipping out of the front end opening by the crimped portion and is rotatably arranged within the ball holder; and a resin sealing member that is a hot melt agent is arranged at the front end of the ballpoint pen tip so as to cover part of the front end of the ballpoint pen tip, including at least part of the mirror-like portion. [Effects of the Invention]

[0007] In the ballpoint pen tip of the present invention, at least a portion of the covering area of ​​the sealing member includes at least a portion of the mirror-like portion having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less, and when the sealing member covers the front end of the ballpoint pen tip, air is less likely to get in between the sealing member and the mirror-like portion, making it easier for them to adhere to each other.This makes it possible to provide a ballpoint pen tip that can prevent the sealing member from unintentionally coming off the ballpoint pen tip, while also allowing a user who wants to remove the sealing member from the ballpoint pen tip to do so without any hassle. [Brief explanation of the drawings]

[0008] [Figure 1] Appearance of ballpoint pen refill 1 [Figure 2] Vertical cross section of ballpoint pen refill 1 [Figure 3] Enlarged view of part B in Figure 1 [Figure 4] Enlarged view of part C in Figure 2 [Figure 5] Enlarged view of the front end of the ball holder 8 where the seal member 17 is arranged [Figure 6] Enlarged view of the front end of the ball holder 8 where the seal member 17 is arranged DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the applicator according to the present invention will be described with reference to the drawings as appropriate. The present invention is not limited to the embodiment, and various modifications can be made without departing from the spirit and scope of the present invention.

[0010] FIG. 1 is an external view of a ballpoint pen refill 1 using a ballpoint pen tip according to the present invention. FIG. 2 is a longitudinal cross-sectional view of the ballpoint pen refill 1. The cross-section shown in FIG. 2 is taken along the center line A of the ballpoint pen refill 1. FIG. 3 is an enlarged view of portion B in FIG. 1. FIG. 4 is an enlarged view of portion C in FIG. 2. The ballpoint pen refill 1 is mainly composed of a ballpoint pen tip 2, a relay member 3, and a pipe 4. In this specification, the side of the ballpoint pen tip 2 along the center line A of the ballpoint pen refill 1 may be referred to as the "front" or "forward," and the opposite side may be referred to as the "rear" or "rearward." In addition, the direction in which the center line A extends may be referred to as the axial direction, the direction perpendicular to the center line A as the radial direction, and the direction along a circle centered on the center line A as the circumferential direction.

[0011] The pipe 4 is a hollow cylindrical member. The pipe 4 is made of polypropylene resin and penetrates in the axial direction. The pipe 4 contains ballpoint pen ink 5. In this embodiment, the ballpoint pen ink 5 is a water-based gel ink, but any ink, such as a general water-based ink or oil-based ink, can be used.

[0012] A backflow preventer 6 is disposed inside the pipe 4, behind the ballpoint pen ink 5, in contact with the rear end surface (interface) of the ballpoint pen ink 5. The backflow preventer 6 is a fluid with a higher viscosity than the ballpoint pen ink 5, and is primarily composed of polybutene. Specifically, the fluid is a mixture of 95.0 wt% polybutene HV50 (polybutene, base material, manufactured by Nippon Petrochemical Co., Ltd.), 3.0 wt% Aerosil R972 (fine particle silica, gelling agent, manufactured by Nippon Aerosil Co., Ltd.), and 2.0 wt% Leopard KL (dextrin fatty acid ester, manufactured by Chiba Flour Mills Co., Ltd.). A float 7 is disposed inside the pipe 4, behind the backflow preventer 6. The float 7 is a member made of polyacetal resin. The backflow preventer 6 and float 7 move forward within the pipe 4 as the ballpoint pen ink 5 is consumed. The backflow preventer 6 and the float 7 can prevent the ballpoint pen ink 5 from leaking from the inside of the pipe 3 and the ballpoint pen ink 5 and its composition from evaporating.

[0013] The material of the pipe 4 can be appropriately selected from polypropylene resin, polycarbonate resin, acrylic resin, polyethylene resin, polyamide resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polyethylene naphthalate resin, vinyl chloride resin, ethylene-vinyl alcohol copolymer, polyacrylonitrile resin, fluororesin, polyacetal resin, polyethylene terephthalate resin, polystyrene resin, ABS resin, silicone resin, elastomer, or composites containing these resins, metals such as stainless steel, steel, brass, and brass, etc., taking into consideration the reactivity with the ballpoint pen ink 5 and the backflow preventive body 6, and the sliding properties with the float 7, etc.

[0014] The material of the backflow preventer 6 can be selected as appropriate, such as those mainly composed of polybutene, aqueous grease made by thickening water, ethylene glycol, glycerin, etc., or oil-based grease made by gelling or thickening simple substances such as silicone, liquid paraffin, or alpha-olefin.

[0015] The material of the float 7 can be appropriately selected from polyacetal resin, polypropylene resin, polycarbonate resin, acrylic resin, polyethylene resin, polyamide resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polyethylene naphthalate resin, vinyl chloride resin, ethylene-vinyl alcohol copolymer, polyacrylonitrile resin, fluororesin, polyethylene terephthalate resin, polystyrene resin, ABS resin, silicone resin, elastomer, or composites containing these resins, metals such as stainless steel, steel, brass, and brass, etc., taking into consideration the reactivity with the ballpoint pen ink 5 and the backflow preventive body 6, and the sliding properties with the inner wall surface of the pipe 4.

[0016] A ballpoint pen tip 2 is arranged in front of the pipe 4 via a relay member 3. The relay member 3 is a hollow cylindrical member that penetrates in the axial direction. The relay member 3 is a member made of polybutylene terephthalate resin. The rear end of the relay member 3 is inserted into the inside of the pipe 4 from the front end opening of the pipe 4. The relay member 3 and the pipe 4 are joined by press fitting. The inside of the relay member 3 forms a flow path for the ballpoint pen ink 5. A ballpoint pen tip 2 is arranged in front of the relay member 3. The rear end of the ballpoint pen tip 2 is inserted from the front end opening of the relay member. The ballpoint pen tip 2 and the relay member 3 are joined by press fitting.

[0017] The ballpoint pen tip 2 is composed of at least a ball holder 8 and a writing ball 9. In this embodiment, a coil spring 10 is also disposed within the ball holder 8. The coil spring 10 is a resilient member made of stainless steel. The coil spring 10 is disposed within the ball holder 8 in a state compressed from its natural length, and constantly presses the writing ball 9 forward. The rear of the coil spring 10 comes into contact with a step formed on the relay member 3 to prevent it from coming off.

[0018] The material of the coil spring 10 can be selected appropriately from stainless steel, hard steel wire, piano wire, polycarbonate resin, polyether ether ketone resin, etc. Also, applying a surface coating treatment such as nickel plating to the surface of the coil spring 10 is preferable because it improves corrosion resistance and prevents components from leaching out into the ballpoint pen ink 5.

[0019] The ball holder 8 is a hollow cylindrical member that penetrates in the axial direction. The ball holder 8 is made of stainless steel. The ball holder 8 is formed with at least a front-end opening 11, a crimped portion 12 that forms the front-end opening 11, a tapered portion 13 located axially rearward of the crimped portion 12 and whose outer diameter decreases toward the front-end opening, and an ink flow hole 14 inside. In this embodiment, the ball holder 8 also has multiple inward protrusions 15 that protrude radially inward from the inner wall surface of the ball holder 8 that forms the ink flow hole 14. Grooves known as arrow grooves are formed between adjacent inward protrusions 15 in the circumferential direction, and function as a flow path for the ballpoint pen ink 5. The writing ball 9 is rotatably arranged in the ball holder 8 in the space formed by the writing crimped portion 12 and the inward protrusions 15.

[0020] A portion of the writing ball 9 protrudes from the front end opening 11. The writing ball 9 is made of a superhard material. The writing ball 9 is pressed forward by a coil spring 10, and is prevented from slipping out of the front end opening 11 by a crimped portion 12. The crimped portion 12 is formed by processing the entire periphery of the front end of the ball holder 8 so that it is bent radially inward.

[0021] The material of the ball holder 8 can be appropriately selected from known materials taking into consideration durability, reactivity with the ballpoint pen ink 5, processability, etc., and it is particularly preferable to use stainless steel, nickel silver, brass, or other copper alloys.

[0022] The material of the writing ball 9 can be selected appropriately taking into consideration wettability with the ballpoint pen ink 5, corrosion resistance, etc., from cemented carbide alloys primarily composed of tungsten carbide, metals such as stainless steel, aluminum, and steel, ceramics such as silicon carbide, silicon nitride, titanium nitride, chromium carbide, alumina, and zirconia, resin materials such as polyethylene resin, polypropylene resin, polyacetal resin, and polyamide resin, and glass.

[0023] The writing ball 9 can be sized to have a diameter of 0.18 mm or more and 2.0 mm or less, but the diameter range of 0.3 mm or more and 1.0 mm or less, which is used in general ballpoint pens, is preferable. In this embodiment, the diameter of the writing ball 9 is 1.0 mm.

[0024] Near the front end of ball holder 8, regions with different outer diameters and curvatures are connected toward the front end. The front end of ball holder 8 is end portion 12a, which is the edge that essentially forms front-end opening 11. Behind end portion 12a, chamfered portion 12b is formed, which is a curved surface with a curvature R of 0.075. Behind chamfered portion 12b, region 12c is formed, where the apex angle of an imaginary cone is 80°, with an imaginary straight line along that region as its ridgeline. Behind region 12c, region 12d is formed, where the apex angle of an imaginary cone is 48°, with an imaginary straight line along that region as its ridgeline. The region from end portion 12a to region 12d is collectively referred to as crimped portion 12. Behind region 12d, tapered portion 13 is formed, where the apex angle of an imaginary cone is 20°, with an imaginary straight line along that region as its ridgeline. A tapered portion 13 with an apex angle of 10° or greater and 30° or less is defined as a tapered portion 13 according to the present invention. By adopting such a configuration, the diameter of the ball holder 8 can be made small near the front end, which is preferable as it improves the visibility of handwriting when it is being formed.

[0025] The crimped portion 12 is not limited to the above-described configuration and can be designed as appropriate taking into account the diameter of the writing ball 9, visibility, and the like. However, at least the tapered portion 13 is formed from a position at an axial distance of at least 0.20 m from the front end of the ball holder 8. By forming the tapered portion 13, whose apex angle is in the range of 10° to 30°, at a position sufficiently far from the front end of the ball holder 8, the tapered portion 13 becomes an area that does not come into contact with the writing surface during writing. Therefore, even if part of the sealing member 17 remains on the surface of the tapered portion 13 after the sealing member described below is removed, this does not affect the writing feel, which is preferable.

[0026] A mirror-finished portion 16 having an arithmetic mean roughness Ra of 90 nm to 250 nm is formed on the tapered portion 13, which is part of the outer wall surface of the ball holder 8. The mirror-finished portion 16 is formed by known physical or chemical surface treatments. For example, by pressing the side wall of a cylindrical spinning roller against the outer wall surface of the ball holder 8 at a desired angle and pressure, the outer wall surface of the ball holder 8 is plastically deformed by the side wall of the rotating spinning roller through rolling, thereby forming the mirror-finished portion 16. The tapered portion 13, which is located axially rearward of the crimped portion 12 and has a smaller angle with respect to the center line A than the crimped portion 12, has a larger area relative to the roller pressed against when forming the mirror-finished portion 16. This allows the mirror-finished portion 16 to be formed without excessively tilting the roller with respect to the center line A compared to the crimped portion 12. The ease of forming the mirror-finished portion 16 makes it easier to configure a ballpoint pen tip 2 that can prevent the seal member 17 from unintentionally coming off, which is preferable. The arithmetic mean roughness of the outer wall surface of the ball holder 8 in the axial direction forward of the tapered portion 13 may be processed to be equivalent to the mirror surface portion 16 .

[0027] A seal member 17 is disposed at the front end of the ball holder 8, which constitutes the front end of the ballpoint pen tip 2. The seal member 17 covers the front end of the ball holder 8, including at least a portion of the front end of the ball holder 8. Figures 5 and 6 are enlarged views of the front end of the ball holder 8 where the seal member 17 is disposed. The seal member 17 is shown transparently, with only the outer edge shown, so that the front end of the ball holder 8 can be seen.

[0028] The sealing member 17 is made of a resin, which is a hot-melt agent. Examples of hot-melt agents include polyethylene resin, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin, ethylene-isobutyl acrylate copolymer resin, polyamide resin, polyester resin, butyral resin, polyvinyl acetate and its copolymers, cellulose derivatives, polymethyl methacrylate resin, polyvinyl ether resin, polyurethane resin, polycarbonate resin, polypropylene resin, vinyl chloride resin, polyacetal resin, polyolefin resin, synthetic rubber resin, and mixtures based on these resins. These agents can be used singly or in combination. Furthermore, tackifiers such as terpene resin, rosin resin, ester gum, coumarone resin, and phenolic resin, softeners such as paraffin oil, waxes such as carnauba wax, natural wax, paraffin wax, polyethylene wax, fatty acid wax, and microcrystalline wax, fillers such as carbon black, talc, clay, silica, calcium carbonate, and inorganic and organic pigments, and adsorbents such as zeolite and silica gel can be added as needed. Specific examples of such products include hot melt adhesives HM200, HM207, HM224, HM245, HM712, HM409, HM360, HM370, and HM373 manufactured by Cemedine Co., Ltd., and hot melt adhesives Meltron A703T, A704, A705, A706, A707, and 1Y15 manufactured by Diabond Kogyo Co., Ltd., and mixtures of two or more of these may be used. Of course, the above-mentioned resins and various additives may also be added as needed. In this embodiment, hot melt adhesive HM200 manufactured by Cemedine Co., Ltd. is used.

[0029] A preferred method for coating the front end of the ball holder 8 with the sealing member 17 is to immerse the front end of the ball holder 8 in a tank containing molten and liquefied hot melt agent, remove the front end of the ball holder 8 from the tank, and allow the hot melt agent adhering to the front end of the ball holder 8 to cool and solidify, thereby coating the front end of the ball holder 8.

[0030] The seal member 17 is disposed so as to cover the ball holder 8, including at least a portion of the mirrored portion 16. As shown in FIG. 5, a portion of the mirrored portion 16 (the shaded area) may be exposed from the covered area of ​​the seal member 17. Alternatively, as shown in FIG. 6, the covered area of ​​the seal member 17 may include the entire area where the mirrored portion 16 is formed. When at least a portion of the covered area of ​​the seal member 17 includes at least a portion of the mirrored portion 16 having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less, and the seal member 17 covers the front end of the ballpoint pen tip 2, air is less likely to enter between the seal member 17 and the mirrored portion 16, and the seal member 17 easily adheres to the ballpoint pen tip 2. This prevents the seal member 17 from unintentionally coming off the ballpoint pen tip 2, while allowing a user who wishes to remove the seal member 17 from the ballpoint pen tip 2 to remove it without any hassle. Specifically, the seal member 17 is preferably removable when the axially forward pulling force applied to the seal member 17 covered by the ball holder 8 is in the range of 2 N or more and 13 N or less.

[0031] If the mirrored portion 16 occupies 18.8% or more and 48.8% or less of the area of ​​the sealing member 17 covering the front end of the ball holder 8, which is the front end of the ballpoint pen tip, this provides a good balance between the resistance to removal that prevents the sealing member 17 from coming off unintentionally and the ease of removal by the user, which is preferable.

[0032] In this embodiment, the area where the seal member 17 covers the front end of the ball holder 8 includes the entire area where the mirror surface portion 16 is formed. This is preferable because it maximizes the effect of preventing the seal member 17 from coming off unintentionally.

[0033] Examples and comparative examples according to the present invention will be described below. The ballpoint pen refills according to each example and comparative example were produced by using the ballpoint pen refill 1 of the above embodiment under the conditions listed in Table 1. Each ballpoint pen ink 5 stored in the pipe 4 was produced with the following composition. In addition, in examples 1 to 12 and comparative examples 1 and 2, the seal member 17 was arranged so that part of the mirrored portion 16 was exposed from the area covered by the seal member 17, as shown in FIG. 5, and in examples 13 to 24, the seal member 17 was arranged so that the area where the mirrored portion 16 was formed was entirely included in the area covered by the seal member 17, as shown in FIG. 6.

[0034] (Ink 1) Water Black #256L (14% aqueous solution of black dye, Orient Chemical Industries Co., Ltd.) ) 35.0 parts by weight Water Yellow #1 (CI Acid Yellow 23, Orient Chemical Industries Co., Ltd.) ) 1.40 parts by weight Ethylene glycol 7.0 parts by weight Glycerin 8.79 parts by weight Thiodiglycol 9.50 parts by weight Sarcosinate OHV (oleoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.) 2.78 parts by weight Benzotriazole 0.25 parts by weight Proxel GXL(S) (20% dipropylene glycol solution of 1,2-benzisothiazolin-3-one, manufactured by Arch Chemicals) 0.18 parts by weight Potassium hydroquinone sulfonate 0.30 parts by weight CWK (ethylenediaminetetraacetic acid tetrasodium salt mixture, manufactured by Orient Chemical Industries Co., Ltd.) 0.60 parts by weight AKP-20 (fine particle alumina, average particle size 0.2 μm, manufactured by Sumitomo Chemical Co., Ltd.) 0.01 parts by weight Sodium hydroxide 0.29 parts by weight Kelzan AR (xanthan gum, manufactured by Sansho Co., Ltd.) 0.45 parts by weight Ion-exchanged water 33.45 parts by weight The above ingredients were mixed with a homomixer for 1 hour. After standing at 50°C for 24 hours, the mixture was stirred with a homogenizer for 10 minutes and passed through a 1-micron thread-wound filter to obtain black ballpoint pen ink 5.

[0035] (Ink 2) Daiwa Red No. 103WB (CI Acid Red 87, manufactured by Daiwa Chemical Industries, Ltd.) 2.43 parts by weight Daiwa Red No. 104WB (CI Acid Red 92, manufactured by Daiwa Chemical Industries, Ltd.) 4.38 parts by weight Water Yellow #6C (CI Acid Yellow 42, manufactured by Orient Chemical Industries Co., Ltd.) 2.00 parts by weight Ethylene glycol 9.72 parts by weight Diethylene glycol 7.30 parts by weight Glycerin 8.79 parts by weight Sarcosinate OHV (oleoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.) 2.78 parts by weight Benzotriazole 1.00 parts by weight Proxel GXL(S) (20% dipropylene glycol solution of 1,2-benzisothiazolin-3-one, manufactured by Arch Chemicals) 0.20 parts by weight Potassium hydroquinone sulfonate 0.30 parts by weight AKP-20 (fine particle alumina, average particle size 0.2 μm, manufactured by Sumitomo Chemical Co., Ltd.) 0.01 parts by weight Sodium hydroxide 0.29 parts by weight Kelzan AR (xanthan gum, manufactured by Sansho Co., Ltd.) 0.45 parts by weight Ion-exchanged water 60.35 parts by weight The above components were mixed with a homomixer for 1 hour. After standing at 50°C for 24 hours, the mixture was stirred with a homogenizer for 10 minutes and passed through a 1-micron thread-wound filter to obtain red ballpoint pen ink 5.

[0036] (Ink 3) Daiwa Red No. 106WB (CI Acid Red 52, manufactured by Daiwa Chemical Industries, Ltd.) 0.41 parts by weight Water Blue #119 (triphenylmethane, manufactured by Orient Chemical Industries Co., Ltd.) 2.18 parts by weight Daiwa Blue No. 1 (CI Acid Blue 9, manufactured by Daiwa Chemical Industry Co., Ltd.) 1.37 parts by weight Ethylene glycol 12.57 parts by weight Glycerin 8.68 parts by weight Thiodiglycol 9.39 parts by weight Sarcosinate OHV (oleoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.) 2.74 parts by weight Benzotriazole 0.99 parts by weight Proxel GXL(S) (20% dipropylene glycol solution of 1,2-benzisothiazolin-3-one, manufactured by Arch Chemicals) 0.20 parts by weight Potassium hydroquinone sulfonate 0.30 parts by weight AKP-20 (fine particle alumina, average particle size 0.2 μm, manufactured by Sumitomo Chemical Co., Ltd.) 0.01 parts by weight Sodium hydroxide 0.28 parts by weight Kelzan AR (xanthan gum, manufactured by Sansho Co., Ltd.) 0.47 parts by weight Ion-exchanged water 60.41 parts by weight The above ingredients were mixed with a homomixer for 1 hour. After standing in a 50°C environment for 24 hours, the mixture was stirred with a homogenizer for 10 minutes and passed through a 1-micron thread-wound filter to obtain blue ballpoint pen ink 5.

[0037] (Ink 4) Daiwa IJ Yellow #306H (CI Direct Yellow 132, manufactured by Daiwa Chemical Industry Co., Ltd.) 0.40 parts by weight Water Yellow #6C (CI Acid Yellow 42, manufactured by Orient Chemical Industries Co., Ltd.) 1.33 parts by weight Water Blue #119 (triphenylmethane, manufactured by Orient Chemical Industries Co., Ltd.) 0.40 parts by weight Daiwa Blue No. 1 (CI Acid Blue 9, manufactured by Daiwa Chemical Industry Co., Ltd.) 1.43 parts by weight Ethylene glycol 12.56 parts by weight Glycerin 8.62 parts by weight Thiodiglycol 9.40 parts by weight Sarcosinate OHV (oleoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.) 2.74 parts by weight Benzotriazole 0.98 parts by weight Proxel GXL(S) (20% dipropylene glycol solution of 1,2-benzisothiazolin-3-one, manufactured by Arch Chemicals) 0.21 parts by weight Potassium hydroquinone sulfonate 0.30 parts by weight AKP-20 (fine particle alumina, average particle size 0.2 μm, manufactured by Sumitomo Chemical Co., Ltd.) 0.01 parts by weight Sodium hydroxide 0.28 parts by weight Kelzan AR (xanthan gum, manufactured by Sansho Co., Ltd.) 0.47 parts by weight Ion-exchanged water 60.87 parts by weight The above ingredients were mixed with a homomixer for 1 hour. After standing in a 50°C environment for 24 hours, the mixture was stirred with a homogenizer for 10 minutes and passed through a 1-micron thread-wound filter to obtain green ballpoint pen ink 5.

[0038] (Ink 5) Daiwa Red No. 106WB (CI Acid Red 52, manufactured by Daiwa Chemical Industries, Ltd.) 2.02 parts by weight Water Blue #119 (triphenylmethane, manufactured by Orient Chemical Industries Co., Ltd.) 0.31 parts by weight Ethylene glycol 12.56 parts by weight Glycerin 8.62 parts by weight Thiodiglycol 9.40 parts by weight Sarcosinate OHV (oleoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.) 2.74 parts by weight Benzotriazole 0.98 parts by weight Proxel GXL(S) (20% dipropylene glycol solution of 1,2-benzisothiazolin-3-one, manufactured by Arch Chemicals) 0.21 parts by weight Potassium hydroquinone sulfonate 0.30 parts by weight AKP-20 (fine particle alumina, average particle size 0.2 μm, manufactured by Sumitomo Chemical Co., Ltd.) 0.01 parts by weight Sodium hydroxide 0.28 parts by weight Kelzan AR (xanthan gum, manufactured by Sansho Co., Ltd.) 0.47 parts by weight Ion-exchanged water 62.10 parts by weight The above ingredients were mixed with a homomixer for 1 hour. After standing at 50°C for 24 hours, the mixture was stirred with a homogenizer for 10 minutes and passed through a 1-micron thread-wound filter to obtain purple ballpoint pen ink 5.

[0039] (Sealing material removal load confirmation test) For each ballpoint pen refill 1 according to each example and comparative example, a jig having a groove with a width smaller than the diameter of the sealing member 17 and larger than the outer diameter of the vicinity of the front end of the ball holder 8 was prepared. The vicinity of the front end of the ball holder 8 was passed through the groove of the jig so that the side on which the sealing member 17 was arranged faced vertically downward, and the pipe 4 positioned on the upper side in the vertical direction was hung on a push-pull gauge (CPU GAUGE 9500 SERIES No. 34084, manufactured by Aiko Engineering Co., Ltd.). When the ballpoint pen refill 1 was pulled up, the sealing member 17 was caught in the groove of the jig, and the load when the sealing member 17 came off the front end of the ballpoint pen tip 2, which is the front end of the ball holder 8, was confirmed.

[0040] [Table 1]

[0041] The ballpoint pen refill 1 in which the ballpoint pen tip 2 according to Examples 1 to 3 is arranged is A mirror-finished portion 16 having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less can be easily formed on the tapered portion 13, which is the outer wall surface of the ball holder 8, and a sealing member 17 is arranged at the front end of the ballpoint pen tip 2 so as to cover at least a portion of the mirror-finished portion 16. This makes it difficult for air to get between the sealing member 17 and the mirror-finished portion 16, making it easier for the two components to adhere to each other. As a result, the load applied when the sealing member 17 is detached from the front end of the ballpoint pen tip 2 is 2.8 N or more and 3.5 N or less, which is a load that can prevent the sealing member 17 from unintentionally detaching from the front end of the ballpoint pen tip 2, but also allows a user who wants to remove the sealing member 17 from the ballpoint pen tip 2 to do so without feeling any hassle.

[0042] In the ballpoint pen refill 1 in which the ballpoint pen tips 2 according to Examples 4 to 12 are arranged, a mirror-like portion 16 having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less can be easily formed on the tapered portion 13 of the outer wall surface of the ball holder 8, and at the front end of the ballpoint pen tip 2, the mirror-like portion 16 occupies 18.8% or more and 48.8% or less of the area covering the front end of the sealing member 17. Therefore, when the sealing member 17 comes off the front end of the ballpoint pen tip 2, the load is 3.8 N or more and 8.8 N or less, which is a good balance between a load that can prevent the sealing member 17 from coming off unintentionally from the front end of the ballpoint pen tip 2 and a load that allows a user who wants to remove the sealing member 17 from the ballpoint pen tip 2 to do so without feeling inconvenienced.

[0043] In the ballpoint pen refill 1 in which the ballpoint pen tips 2 according to Examples 13 to 15 are arranged, a mirror-like portion 16 having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less can be easily formed on the tapered portion 13, which is the outer wall surface of the ball holder 8. The covering area of ​​the sealing member 17 is arranged at the front end of the ballpoint pen tip 2 so as to cover the entire mirror-like portion 16. This makes it difficult for air to get between the sealing member 17 and the mirror-like portion 16, making it easier for the two members to adhere to each other. As a result, the load when the sealing member 17 is detached from the front end of the ballpoint pen tip 2 is 9.4 N or more and 12.8 N or less, which is a large load that is highly effective in preventing the sealing member 17 from unintentionally detaching from the front end of the ballpoint pen tip 2, but is also a load that allows a user who wants to remove the sealing member 17 from the ballpoint pen tip 2 to remove it without feeling any hassle.

[0044] In the ballpoint pen refill 1 in which the ballpoint pen tips 2 according to Examples 16 to 24 are arranged, a mirror-like portion 16 having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less can be easily formed on the tapered portion 13, which is the outer wall surface of the ball holder 8. At the front end of the ballpoint pen tip 2, the sealing member 17 is arranged so that the mirror-like portion 16 occupies 18.8% or more and 48.8% or less of the area covering the front end of the ballpoint pen tip 2, and the covering area of ​​the sealing member 17 covers the entire mirror-like portion 16. Therefore, when the sealing member 17 is detached from the front end of the ballpoint pen tip 2, the load is 3.9 N or more and 8.5 N or less, which is a load that is large enough to prevent the sealing member 17 from unintentionally detaching from the front end of the ballpoint pen tip 2, but is well-balanced with a load that allows a user who wants to remove the sealing member 17 from the ballpoint pen tip 2 to remove it without feeling inconvenienced.

[0045] The ballpoint pen refill 1 in which the ballpoint pen tip 2 of Comparative Example 1 is placed has a mirror-like portion 16 with an arithmetic mean roughness Ra of less than 90 nm formed on the tapered portion 13, which is the outer wall surface of the ball holder 8, and a sealing member 17 is placed at the front end of the ballpoint pen tip 2 so as to cover at least a portion of the mirror-like portion 16. When the sealing member 17 is removed from the front end of the ballpoint pen tip 2, the load applied is 19.9 N, which is a load that makes it difficult to remove the sealing member 17 from the front end of the ballpoint pen tip 2.

[0046] In the ballpoint pen refill 1 in which the ballpoint pen tip 2 of Comparative Example 2 is arranged, a mirror-like portion 16 having an arithmetic mean roughness Ra of more than 250 nm is formed on the tapered portion 13, which is the outer wall surface of the ball holder 8, and a sealing member 17 is arranged at the front end of the ballpoint pen tip 2 so as to cover at least a portion of the mirror-like portion 16. When the sealing member 17 comes off the front end of the ballpoint pen tip 2, the load applied is 1.5 N, which is a load that makes it easy for the sealing member 17 to come off unintentionally from the front end of the ballpoint pen tip 2. [Explanation of symbols]

[0047] 1 ballpoint pen refill 2 ballpoint pen tips 3 Relay parts 4 Pipes 5. Ballpoint pen ink 6 Backflow prevention body 7. Float 8 ball holder 9 Writing Ball 10 coil springs 11 Front end opening 12 Crimping part 12a Edge part 12b Chamfered part 12c area 12d area 13 Tapered section 14 Ink flow hole 15 Inward protrusion 16 Mirror surface part 17 Sealing material

Claims

1. A ballpoint pen tip comprising at least a ball holder and a writing ball, The ball holder is formed with at least a front end opening, a crimped portion that forms the front end opening, a tapered portion that is located axially rearward of the crimped portion and whose outer diameter decreases toward the front end opening, and an ink flow hole therein; a mirror-finished portion having an arithmetic mean roughness Ra of 90 nm or more and 250 nm or less is formed on the tapered portion of the outer wall surface of the ball holder; The writing ball protrudes partially from the front end opening, is prevented from slipping out of the front end opening by a crimped portion, and is rotatably disposed within the ball holder. At the front end of the ballpoint pen tip, a resin sealing member, which is a hot melt agent, is arranged so as to cover a part of the front end of the ballpoint pen tip, including at least a part of the mirror surface portion. Ballpoint pen tip.

2. The mirror surface portion occupies 18.8% or more and 48.8% or less of the area of ​​the sealing member covering the front end of the ballpoint pen tip. The ballpoint pen tip according to claim 1 .

3. The covering area of ​​the sealing member includes the entire mirror surface portion. The ballpoint pen tip according to claim 1 or 2.

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