ballpoint pen refills

Abstract

To provide a resin coating capable of obtaining adhesion strength to the tip of a ball-point pen tip and also improving impact resistance.SOLUTION: There is provided a ball-point pen refill including a ball-point pen tip which has a holder, a writing ball held by the holder, and a resin coating adhering to and covering the writing ball and the tip of the holder. The resin coating has an inner layer coating that directly adheres to the tip of the holder and an outer layer coating that covers the inner layer coating. The outer layer coating of the resin coating has a lower hardness than the inner layer coating.SELECTED DRAWING: Figure 1C

Description

[Technical Field]

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

[0002] In ballpoint pen refills that use volatile inks such as water-based inks and gel inks, a resin coating made of a thermoplastic resin is sometimes applied to the tip of the ballpoint pen tip of the ballpoint pen refill to protect the tip of the ballpoint pen tip and prevent the ink from volatilizing after manufacturing. This resin coating is required to prevent the tip from falling off when touched by a user when the ballpoint pen is sold, and from cracking due to impact when the ballpoint pen is dropped.

[0003] For example, the prior art described in Patent Document 1 discloses a method in which a thermoplastic resin is applied to the tip of a ballpoint pen tip so as to coat it, and then cooled to room temperature and reheated to increase the adhesive strength.

[0004] Furthermore, for example, the prior art described in Patent Document 2 discloses a technique for improving the adhesive strength of a resin coating by forming a recess on the outer surface of the tip end of the tip body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 5585424 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-225584 Summary of the Invention [Problem to be solved by the invention]

[0006] However, while the prior art described in Patent Document 1 makes it possible to improve the adhesive strength so that the ballpoint pen is less likely to fall off when touched by a user, it does not disclose a method for withstanding the impact when the ballpoint pen is dropped.

[0007] Another possible method is to select a soft material for the coating to withstand impact, but in this case, there is a risk that the resin coating will reduce the adhesive strength to the tip of the ballpoint pen tip.

[0008] The prior art described in Patent Document 2 can improve the adhesive strength of the thermoplastic resin, but it may increase manufacturing costs because it requires forming a protrusion at the tip of the ballpoint pen tip.

[0009] The embodiments of the present application have been made in consideration of the above-mentioned problems, and aim to obtain a resin coating that has adhesive strength to the tip of a ballpoint pen tip and also has improved impact resistance. [Means for solving the problem]

[0010] A ballpoint pen refill according to a first embodiment of the present application has a ballpoint pen tip equipped with a writing ball, a holder that holds the writing ball, and a resin coating that covers the area from the tip of the writing ball to a portion of the tip of the holder, wherein the resin coating has an inner layer coating that is directly attached to the tip of the holder and an outer layer coating that covers the inner layer coating, and the outer layer coating of the resin coating has a lower hardness than the inner layer coating.

[0011] Furthermore, the inner coating layer of the ballpoint pen refill according to the second embodiment of the present application preferably has higher adhesive strength than the outer coating layer of the ballpoint pen refill according to the first embodiment of the present application.

[0012] Furthermore, the inner layer coating of the ballpoint pen refill according to the third embodiment of the present application preferably has a softening temperature higher than that of the outer layer coating in the ballpoint pen refill according to the first embodiment or the second embodiment of the present application.

[0013] Furthermore, it is preferable that the inner layer coating of the ballpoint pen refill according to the fourth embodiment of the present application has lower water vapor permeability than the outer layer coating in the ballpoint pen refills according to the first to third embodiments of the present application.

[0014] Furthermore, it is preferable that the inner layer coating of the ballpoint pen refill according to the fifth embodiment of the present application is colored a different color from the outer layer coating in the ballpoint pen refills according to the first embodiment to the fourth embodiment of the present application. [Effects of the Invention]

[0015] According to the embodiment of the present application, it is possible to provide a ballpoint pen refill using a resin coating that can obtain adhesive strength to the tip of the ballpoint pen tip and also improve impact resistance. [Brief explanation of the drawings]

[0016] [Figure 1A] 1 is a diagram showing a ballpoint pen refill according to an embodiment of the present application. [Figure 1B] 1 is a diagram showing a cross section of a ballpoint pen refill according to an embodiment of the present application. [Figure 1C] 1 is a diagram showing a cross section of a ballpoint pen tip according to an embodiment of the present application. [Figure 2] FIG. 10 is a diagram showing a cross section of a ballpoint pen tip according to a modified example of an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0017] [First embodiment] A ballpoint pen refill 10 according to an embodiment of the present disclosure will be described with reference to Figures 1A to 1C as appropriate. In the following description, the side of the ballpoint pen refill 10 to which the ballpoint pen tip 16 is attached will be referred to as the "front end side," and the opposite side will be referred to as the "rear end side."

[0018] (composition) 1A is a diagram showing a ballpoint pen refill 10 according to one embodiment of the present disclosure. The ballpoint pen refill 10 has a substantially cylindrical ink reservoir 12, a joint 14 which is a hollow member connected to the tip of the ink reservoir 12, and a ballpoint pen tip 16 which is held at the tip of the joint 14 and transfers ink 22 onto a paper surface.

[0019] 1B is a diagram showing a cross section of a ballpoint pen refill 10 according to an embodiment of the present disclosure. As shown in FIG. 1B, the ink reservoir 12 contains ink 22 therein, is connected at its front end to a joint 14, and contains a follower 20 at its rear end. The ink reservoir 12 is made of a synthetic resin such as polypropylene.

[0020] The ink 22 is contained inside the ink reservoir tube 12. The ink 22 passes through the inside of a joint 14 (described later) and is supplied to the ballpoint pen tip 16. The ink 22 is, for example, a water-based ink or a water-based gel ink.

[0021] The follower 20 is, for example, non-volatile grease, and prevents the ink 22 from volatilizing from the rear end side of the ink containing tube 12.

[0022] The joint 14 holds, for example, the ballpoint pen tip 16 by fitting it externally, and is also fitted internally into and connected to the ink containing tube 12. As described above, the joint 14 supplies the ink 22 contained in the ink containing tube 12 to the ballpoint pen tip 16 inside the joint 14. The joint 14 is made of a synthetic resin such as ABS, PP, or PBT.

[0023] 1C is a diagram showing a cross section of a ballpoint pen tip 16 according to an embodiment of the present disclosure. As shown in FIG. 1B and FIG. 1C, the ballpoint pen tip 16 includes a holder 24, a spring 36 housed inside the holder 24, a writing ball 44 held by a tip portion 34 formed on the tip side of the holder 24, and a resin coating 18 that adheres to and covers the writing ball 44 and the tip of the holder 24.

[0024] The holder 24 has a generally cylindrical intermediate portion 30, a connecting portion 32 formed by hollowing out the rear end side of the intermediate portion 30, and a tip portion 34 formed by hollowing out the front end side of the intermediate portion 30. The holder 24 is made of a metal such as stainless steel.

[0025] The connecting portion 32 has an outer diameter smaller than that of the intermediate portion 30 of the holder 24, and is fitted into and held by the fitting 14, while supplying ink 22 from the ink containing tube 12 to the intermediate portion 30 therein. The intermediate portion 30 also supplies ink 22 from the connecting portion 32 to the tip portion 34 therein.

[0026] The tip portion 34 has, for example, a tapered portion 40 whose outer diameter tapers from the intermediate portion 30 toward the tip side of the holder 24, a tapered tip portion 42 formed on the tip side of the tapered portion 40, and a crimped portion 46 crimped inward on the tip side of the tapered tip portion 42. The tapered portion 40 also supplies ink 22 from the intermediate portion 30 to the tapered tip portion 42 inside.

[0027] The tip reduced diameter section 42 is formed, for example, into a cylindrical shape at the tip of the tapered section 40. Furthermore, the tip side of the tip reduced diameter section 42 is crimped inward so that the opening on the tip side of the tip reduced diameter section 42 is smaller in size than the writing ball 44 while the writing ball 44 (described later) is held inside, forming a crimped section 46. Furthermore, ink 22 is supplied from the tapered section 40 to the writing ball 44 inside.

[0028] The writing ball 44 is rotatably held by the crimped portion 46 at the tapered tip portion 42, is exposed to the outside through an opening formed at the tip side of the tapered tip portion 42, and is supplied with ink 22 inside the tapered tip portion 42. The writing ball 44 rolls while contacting the surface of paper or the like at the tip side of the tapered tip portion 42, thereby transferring the ink 22 adhering to the surface of the writing ball 44 to the paper or the like. The writing ball 44 is capable of continuously transferring the ink 22 to the paper surface by continuously adhering the ink 22 supplied inside the tapered tip portion 42 to its surface. The writing ball 44 is made of a cemented carbide alloy.

[0029] Here, the resin coating 18 according to one embodiment of the present disclosure has a first resin coating 50, which is an inner layer coating that directly adheres from the tip of the holder 24 to the tapered portion 40 of the tip portion 34, and a second resin coating 52, which is an outer layer coating that adheres to the tip portion 34 of the holder 24 while tightly covering the first resin coating 50. Here, the material of the first resin coating 50 is a first thermoplastic resin, and the material of the second resin coating 52 is a second thermoplastic resin.

[0030] The first resin coating 50 is formed, for example, by immersing the ballpoint pen tip 16 from the tip to the tapered portion 40 in a first thermoplastic resin that has been heated to a softening temperature or higher and melted, and then adhering the first resin coating 50. As a result, the first resin coating 50 adheres to the tip of the holder 24 while tightly covering the writing ball 44, the tapered tip portion 42, and the tapered portion 40.

[0031] The second resin coating 52 is formed, for example, by immersing the ballpoint pen tip 16 having the first resin coating 50 from the tip to the tapered portion 40 in a second thermoplastic resin that has been heated to or above its softening temperature and melted, and adhering the second resin coating 52 so as to cover the first resin coating 50. As a result, the second resin coating 52 adheres to the tapered portion 40 while tightly covering the first resin coating 50 described above.

[0032] Here, the materials for the first resin coating 50 and the second resin coating 52 are selected based on the following conditions.

[0033] First, in order for the first resin coating 50 to tightly cover the writing ball 44 at the tip portion 34 and to reliably adhere to the tapered portion 40, a first thermoplastic resin is selected that has adhesive strength to the tip portion 34 and the writing ball 44, i.e., adhesiveness to the tip portion 34 and the writing ball 44.

[0034] Next, the second resin coating 52 tightly covers the first resin coating 50, and in order to improve resistance to external impact, a second thermoplastic resin that is softer than the first resin coating 50 is selected during distribution after manufacture.

[0035] In this way, the resin coating 18 of this embodiment ensures adhesion strength to the writing ball 44 and tapered portion 40 through the first resin coating 50, while the second resin coating 52 provides softness, thereby ensuring impact resistance.

[0036] The hardness of the first thermoplastic resin and the second thermoplastic resin was measured using a durometer (D type), and the obtained hardness value is indicated by HDD, which is the symbol for durometer hardness. The hardness value obtained for the second thermoplastic resin is lower than the hardness value obtained for the first thermoplastic resin, which is considered to be "softer."

[0037] (Action and effect) In one embodiment of the present disclosure, the resin coating 18 ensures adhesion to the tip of the ballpoint pen tip 16 through the first resin coating 50, and improves impact resistance when an impact is applied to the tip of the ballpoint pen tip 16 through the second resin coating 52.

[0038] Therefore, the resin coating 18 according to one embodiment of the present disclosure has the first resin coating 50 and the second resin coating 52, which makes it possible to both ensure adhesion strength to the tip of the ballpoint pen tip 16 and improve impact resistance against impact to the tip of the ballpoint pen tip 16.

[0039] As described above, the resin coating 18 according to one embodiment of the present disclosure is formed by first applying a first thermoplastic resin that has been heated to above its softening temperature and melted to the tip of the ballpoint pen tip 16, and then applying another thermoplastic resin that has been heated to above its softening temperature and melted to the tip of the ballpoint pen tip 16 so as to cover the first resin coating 50.

[0040] Here, if the first thermoplastic resin has a lower softening temperature than the second thermoplastic resin, the first resin coating 50 will soften during the process of adhering the second resin coating 52 to the first resin coating 50, which may result in a decrease in adhesion strength.

[0041] Furthermore, if the first thermoplastic resin has a lower softening temperature than the second thermoplastic resin, there is a risk of deterioration due to mixing of the first resin coating 50 and the second resin coating 52 during the process of adhering the second resin coating 52 to the first resin coating 50.

[0042] However, if the softening temperature of the second thermoplastic resin is lower than that of the first thermoplastic resin, the second resin coating 52 can be applied at a temperature at which the first resin coating 50 does not soften, thereby reducing the risk of this happening. Therefore, it is more preferable to use a material for the first resin coating 50 that has a higher softening temperature than the second resin coating 52.

[0043] As described above in detail, by attaching layers of thermoplastic resins with different properties to the tip of the ballpoint pen tip 16, it is possible to achieve a variety of performances.

[0044] (Variation) A modified example of the ballpoint pen refill 10 according to the present disclosure will be described with reference to FIG. 2 as needed. 2 is a diagram of a ballpoint pen refill 10 according to a modified example of an embodiment of the present disclosure. In this modified example, the tapered tip portion 42 is formed longer in the axial direction of the ballpoint pen refill 10 than in the embodiment of the present disclosure, and the resin coating 18 is attached only to the tapered tip portion 42.

[0045] In the ballpoint pen tip 16 according to this modification, the tapered tip portion 42 is formed longer in the axial direction of the ballpoint pen refill 10 than in the first embodiment, and therefore the resin coating 18 is less likely to come off than in the tapered tip portion 42 of the ballpoint pen tip 16 according to the first embodiment. This makes it possible to reduce the amount of resin coating 18 used while maintaining the same adhesive strength as the ballpoint pen tip 16 according to the first embodiment.

[0046] In addition, in order to prevent the resin coating 18 according to one embodiment of the present disclosure from falling off from the tip of the ballpoint pen tip 16, it is sufficient that adhesive strength is obtained by only one of the first resin coating 50 or the second resin coating 52.

[0047] Therefore, the first resin coating 50 and the second resin coating 52 may be formed using thermoplastic resins with different adhesive strengths. For example, since the first resin coating 50 is an inner layer, the adhesive strength of the resin coating 18 can be obtained by using a first thermoplastic resin with a higher adhesive strength than the second thermoplastic resin. In other words, by requiring adhesive strength for the first resin coating 50, it is possible to increase the degree of freedom in selecting the second thermoplastic resin.

[0048] The adhesive strength of the first thermoplastic resin and the second thermoplastic resin is measured according to the following procedure. First, the area of ​​the first thermoplastic resin and the second thermoplastic resin attached to the ballpoint pen tip 16 is measured. Next, a force is applied to the resin coating 18 to peel it off the ballpoint pen tip 16, and the force at which the resin coating 18 is peeled off the ballpoint pen tip 16 is measured. The force at which the resin coating 18 is peeled off the ballpoint pen tip 16 is then divided by the area of ​​the resin coating 18 attached to the ballpoint pen tip 16 to obtain the adhesive strength. In this way, the adhesive strength value of the first thermoplastic resin is determined to be higher than the adhesive strength value of the second thermoplastic resin.

[0049] Furthermore, in order to suppress the evaporation of ink 22 by the resin coating 18 according to one embodiment of the present disclosure, it is sufficient that the evaporation of ink 22 can be suppressed by only one of the first resin coating 50 or the second resin coating 52 in order to suppress the evaporation of ink 22 from the tip of the ballpoint pen tip 16.

[0050] Therefore, the first resin coating 50 and the second resin coating 52 may be formed using thermoplastic resins with different water vapor permeabilities. For example, the first thermoplastic resin, which is the material of the first resin coating 50 that comes into direct contact with the writing ball 44, may be a material with a lower water vapor permeability than the second thermoplastic resin, thereby suppressing the evaporation of the ink 22.

[0051] This makes it possible to increase the freedom of selection of the thermoplastic resins used to form the first resin coating 50 and the second resin coating 52 by requiring a water vapor permeability for either the first resin coating 50 or the second resin coating 52.

[0052] The water vapor permeability of the first thermoplastic resin and the second thermoplastic resin is measured using a weight scale after leaving them in a thermostatic chamber at 50° C. for one month. The water vapor permeability value obtained by measurement is expressed as the weight loss due to evaporation as a percentage.

[0053] Furthermore, in order to form the resin coating 18 according to one embodiment of the present disclosure, it is necessary to recognize at the time of manufacturing that the first resin coating 50 and the second resin coating 52 have been formed.

[0054] In this case, by using thermoplastic resins that are colored differently for the first resin coating 50 and the second resin coating 52, it becomes possible to easily recognize the formation of the first resin coating 50 and the second resin coating 52 during manufacturing.

[0055] The first resin coating 50 and the second resin coating 52 may be formed using a material other than a thermoplastic resin. For example, the resin coating 18 according to an embodiment of the present disclosure may be formed using a thermosetting resin, an ultraviolet curing resin, or the like.

[0056] In addition, in one embodiment of the present disclosure, the resin coating 18 has been described as consisting of the first resin coating 50 and the second resin coating 52, but the resin coating 18 according to the present disclosure is not limited to this, and may be formed into multiple layers by adhering multiple resins. [Example]

[0057] Next, the following experiment was conducted to verify the effects of one embodiment of the present disclosure. (Experimental Method) The adhesive strength and impact resistance were measured using ballpoint pens equipped with ballpoint pen refills 10 for Comparative Example 1, where the resin coating 18 was formed using only the first thermoplastic resin; Comparative Example 2, where the resin coating 18 was formed using only the second thermoplastic resin; and Example, where the resin coating 18 was formed by forming a first resin coating 50 using the first thermoplastic resin and then forming a second resin coating 52 covering the first resin coating 50 using the second thermoplastic resin.

[0058] In Comparative Example 1, the first thermoplastic resin was Hibon 9877 (softening point 111°C) manufactured by Showa Denko Materials Co., Ltd., which was heated to a temperature above the softening point, melted, and immersed in the first thermoplastic resin from the tip of the ballpoint pen tip 16 to the tapered portion 40, thereby adhering the first thermoplastic resin to form a resin coating 18.

[0059] In Comparative Example 2, the second thermoplastic resin was HC126-B (softening point 104°C) manufactured by Bostik-Nitta Corporation, which was heated to a temperature above the softening point, melted, and immersed in the ballpoint pen tip 16 from the tip to the tapered portion 40, causing it to adhere to the tip and form a resin coating 18.

[0060] In the examples, the first thermoplastic resin was Hibon 9877 manufactured by Showa Denko Materials Inc., which was heated to a temperature above the softening point of the first resin coating 50, melted, and immersed in and adhered to the ballpoint pen tip 16 from the tip to the tapered portion 40, forming the first resin coating 50. Thereafter, the second thermoplastic resin was HC126-B manufactured by Bostik-Nitta Corporation, which was heated to a temperature above the softening point but below the softening point of the first resin coating 50, melted, and immersed in and adhered to the ballpoint pen tip 16 from the tip to the tapered portion 40, covering the first resin coating 50, forming the resin coating 18.

[0061] Table 1 shows the physical properties and components of the first thermoplastic resin and the second thermoplastic resin.

[0062] [Table 1]

[0063] The softening points of the first thermoplastic resin and the second thermoplastic resin were measured by a ring and ball softening point test.

[0064] The hardness of the first thermoplastic resin and the second thermoplastic resin was measured using a durometer (type D).

[0065] The ballpoint pen tip 16 used in the experiment had a writing ball 44 with a diameter of 0.38 mm and a tip apex angle of 30°. The ballpoint pen tip 16 was made of a cemented carbide alloy for the writing ball 44 and stainless steel for the holder 24. The ink 22 had the following composition: Microspheres: 15 parts by mass Xanthan gum (thickener, KESLAN S, Sansei): 0.18 parts by mass Phosphate ester (Plysurf A219B, Daiichi Kogyo Seiyaku): 0.5 parts by mass Preservative (Biodene 421, Yamato Chemical Industry): 0.2 parts by mass Benzotriazole (rust inhibitor): 0.3 parts by mass Aminomethylpropanol (pH adjuster): 0.1 parts by mass, Propylene glycol (solvent): 15 parts by mass, Ion-exchanged water: Remaining

[0066] The adhesive strength of the resin coating 18 under each condition was measured using the procedure described above.

[0067] The impact resistance of the resin coating 18 under each condition was evaluated using the following procedure. First, the ballpoint pen was dropped freely onto a concrete surface from a height of 0.75 m so that the tip of the ballpoint pen would hit the concrete. Next, the impact resistance was evaluated by checking whether the resin coating 18 had fallen off the ballpoint pen tip 16 or whether the resin coating 18 had cracked.

[0068] The water vapor permeability of the resin film 18 under each condition was measured using the procedure described above.

[0069] Table 2 shows the results of the adhesive strength, impact resistance test, and water vapor permeability test of the resin coating 18.

[0070] [Table 2]

[0071] In Table 2, "A" indicates a test product in which the resin coating 18 did not fall off or crack during the impact resistance test, and "B" indicates a test product in which the resin coating 18 fell off or cracked during the impact resistance test.

[0072] From Table 2, it can be seen that by adhering the first resin coating 50 and the second resin coating 52 in layers, the first resin coating 50 has adhesive strength and the second resin coating 52 has impact resistance. [Industrial Applicability]

[0073] A ballpoint pen refill having a ballpoint pen tip according to the present disclosure can be used to protect a writing instrument containing ink. [Explanation of symbols]

[0074] 10 Ballpoint pen refill 12 Ink reservoir tube 14 Joint 16 Ballpoint pen tip 18 Resin coating 20 Follower 22 Ink 24 Holder 30 Middle section 32 Connection section 34 Tip 36 Spring 40 Tapered portion 42 Tip reduced diameter portion 44 Writing ball 46 Crimping part 50 First resin coating 52 Second resin coating

Claims

1. A holder and a writing ball held by the holder; a resin coating that adheres to and covers the tip of the writing ball and the holder; a ballpoint pen tip comprising: the resin coating has an inner layer coating that is directly attached to the tip of the holder and an outer layer coating that covers the inner layer coating, the outer layer of the resin coating has a lower hardness than the inner layer, The inner coating layer has a higher adhesive strength than the outer coating layer, and the adhesive strength is a value obtained by dividing the force exerted when the inner layer coating and the outer layer coating are peeled off from the ballpoint pen tip after the inner layer coating and the outer layer coating are attached to the ballpoint pen tip by the area of ​​each of the inner layer coating and the outer layer coating attached to the ballpoint pen tip. Ballpoint pen refill.

2. The inner coating layer has a softening temperature higher than that of the outer coating layer. The ballpoint pen refill according to claim 1.

3. The inner layer coating further has a lower water vapor permeability than the outer layer coating. The ballpoint pen refill according to claim 1 or 2.

4. The inner coating is further colored a different color from the outer coating. The ballpoint pen refill according to any one of claims 1 to 3.

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